Kotera, Kouhei (Osaka, JP)
Matsushima, Tomoaki (Osaka, JP)
Matsushita, Yukio (Osaka, JP)
Nakanishi, Hideo (Osaka, JP)
Hashimoto, Shinji (Osaka, JP)
Nemoto, Tomoaki (Osaka, JP)
Yagyu, Hiroyuki (Osaka, JP)
Kasai, Yuuki (Osaka, JP)
Plaque It!
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1. A material for an optical circuit-electrical circuit mixedly mounting substrate comprising: a light permeable resin layer, and an optical circuit forming layer that is made of a light permeable resin of which refractive index decreases when irradiated with an activating energy beam and is disposed adjacent to the light permeable resin layer, wherein when the material for the optical circuit-electrical circuit mixedly mounting substrate with an activating energy beam is irradiated so as to irradiate a portion of the optical circuit forming layer, the refractive index of said portion is higher than that of the remaining non-irradiated portion of the optical circuit forming layer. The material for the optical circuit-electrical circuit mixedly mounting substrate is again a composite material as in the above wherein at least two layers are stacked, namely a laminate structure.
2. The material for the optical circuit-electrical circuit mixedly mounting substrate according to claim 1 further comprising a second light permeable resin layer, wherein the optical circuit forming layer is disposed between the light permeable resin layer and the second light permeable resin layer, and when the activating energy beam is applied to the material for the optical circuit-electrical circuit mixedly mounting substrate so that a portion of the optical circuit forming layer is irradiated with the activating energy beam, a refractive index of the rest of the optical circuit forming layer is higher than that of the second light permeable resin layer.
3. A material for an optical circuit-electrical circuit mixedly mounting substrate comprising: a metal layer, and an optical circuit forming layer that is made of a light permeable resin of which refractive index decreases when irradiated with an activating energy beam and is disposed adjacently to the metal layer, wherein when the material for the optical circuit-electrical circuit mixedly mounting substrate is irradiated with the activating energy beam on a portion of the optical circuit forming layer, the refractive index of said portion of the optical circuit forming layer irradiated with the activating energy beam is lower than that of the rest of the optical circuit forming layer that is not irradiated with the activating energy beam.
4. The material for the optical circuit-electrical circuit mixedly mounting substrate according to claim 3 further comprising a light permeable resin layer, wherein the optical circuit forming layer is disposed between the metal layer and the light permeable resin layer, and when the activating energy beam is applied to the material for the optical circuit-electrical circuit mixedly mounting substrate so that a portion of the optical circuit forming layer is irradiated with the activating energy beam, the refractive index of the rest of the optical circuit forming layer that has not been irradiated with the activating energy is higher than that of the light permeable resin layer.
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a Divisional of application Ser. No. 10/515,175, which is a National Stage of International Application No. PCT/JP03/06569, filed May 27, 2003.
This application also claims priority of Japanese Application Nos. 2002-154809, filed May 28, 2002, and 2002-154810, filed May 28, 2002.
The entire disclosures of each of the above-cited applications, including application Ser. No. 10/515,175, International Application No. PCT/JP03/06569, and Japanese Application Nos. 2002-154809 and 2002-154810, are considered as being part of this application, and the entire disclosures of each of these applications are expressly incorporated by reference herein in their entireties.
TECHNICAL FIELD
The present invention relates to a material which can be used as a raw material for manufacturing a substrate including an optical circuit (a circuit that transmits light) and an electrical circuit (or electrical wiring) together, that is a substrate which mounts an optical circuit and an electrical circuit mixedly (or together) (hereinafter which substrate is also referred to as an “optical circuit-electrical circuit mixedly mounting substrate”), and a method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate. According to the present invention, the optical circuit and the electrical circuit may respectively be a part thereof, and in this respect the optical circuit and the electrical circuit may be an optical line or an optical waveguide and an electrical wiring, respectively. The optical circuit-electrical circuit mixedly mounting substrate is also referred to as an “electrical-optical circuit board.”
BACKGROUND ART
Recently, as the adoption of broadband technology in the communication infrastructure proceeds in an explosive pace and the information processing capacity of computers and other hardware increases at a dramatic pace, there are increasing needs for an information processing circuit that has a very fast information transmission line. Thus as a means for breaking through the limit of transmission speed of electrical signals, transmission of information in the form of optical signals has been studied and various attempts have been made on the technology to mount an optical circuit on a substrate that has an electrical circuit formed thereon.
The basic idea of mounting the electrical circuit and the optical circuit together is to form in addition to the existing electrical circuit the optical circuit on the conventional printed circuit board. For the manufacture of the optical circuit-electrical circuit mixedly mounting substrate where the optical circuit and the electrical circuit are stacked in multiple layers, the following two methods have mainly been proposed:
With one method, a cladding layer, a core layer and a cladding layer that constitute an optical waveguide of the optical circuit are stacked one on another on a substrate whereon an electrical circuit has been formed, and an electrical wiring layer is further formed thereon by plating or the like.
With the other method, a cladding layer, a core layer and a cladding layer are stacked one on another on a dummy circuit board to form an optical waveguide that constitutes an optical circuit, then the optical waveguide is bonded onto a printed circuit board followed by removing the dummy circuit board, and an electrical circuit is formed on the optical waveguide by plating or the like. Reference may be made for this method to, for example, Japanese Unexamined Patent Publication No. 2001-15889.
The methods mentioned above have such problems that a number of steps is large which are required for stacking by forming the optical circuit and the electrical circuit successively. The accuracy of wiring is low when forming the electrical circuit by plating as is the common practice in the prior art. Thus it is difficult to manufacture high-quality optical circuit-electrical circuit mixedly mounting substrates stably on a industrial basis.
DISCLOSURE OF THE INVENTION
Considering the above described problems, the present invention has an object of providing a material for an optical circuit-electrical circuit mixedly mounting substrate which allows the production of the optical circuit-electrical circuit mixedly mounting substrate of a high quality with a simple method by using the conventional printed circuit board manufacturing technology, and providing a method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate.
In this specification, the material for the optical circuit-electrical circuit mixedly mounting substrate has an “optical circuit forming layer” as a constituent layer thereof. The “optical circuit forming layer” refers to a layer in which at least a core of a light propagating waveguide can be formed. The core is the portion through which the light is transmitted, and corresponds to the above-mentioned optical circuit.
“Activating energy beam” refers to electromagnetic radiation that has energy enough to change a solubility to solvent or a refractive index of a resin that constitutes the optical circuit forming layer (that is, to activate the resin so as to change the property for that purpose) when forming such a waveguide. The activating energy beam may be for example ultraviolet ray, laser beam of various wavelengths, electron beam, X-ray or the like. These various activating energy beam may be regarded as a kind of light in its broad sense.
When the solubility to solvent or the refractive index of the optical circuit forming layer changes with the irradiation of the activating energy beam, it is desirable that the solubility to solvent or the refractive index of the other components (for example, a light permeable resin layer) that constitute the material for optical circuit-electrical circuit mixedly mounting substrate does not substantially change. However, in the case wherein it does change, the refractive index of the core that constitutes the optical waveguide is higher than those of portions around the core after the irradiation.
In a first aspect, the present invention provides a material for an optical circuit-electrical circuit mixedly (or together) mounting substrate comprising:
a light permeable (or transparent) resin layer, and
an optical circuit forming layer that is made of a light permeable resin of which refractive index increases when irradiated with an activating energy beam and is disposed adjacent to the light permeable resin layer,
wherein a refractive index of a portion of the optical circuit forming layer is higher than that of the light permeable resin layer after the material for the optical circuit-electrical circuit mixedly mounting substrate is irradiated with an activating energy beam so that said portion is irradiated. The material for the optical circuit-electrical circuit mixedly mounting substrate is a composite material wherein at least two layers are stacked, namely a laminate structure.
The material according to the first aspect has the light permeable resin layer (or a transparent resin layer) and the optical circuit forming layer adjoining thereto, and the optical circuit forming layer is made of the light transparent resin of which refractive index increases when irradiated with the activating energy beam. When the activating energy beam is applied to the material for the optical circuit-electrical circuit mixedly mounting substrate so that a portion of the optical circuit forming layer is irradiated with the activating energy beam, a refractive index of the irradiated portion increases to be higher than that of the non-irradiated portion in the optical circuit forming layer. Since the portion irradiated with the activating energy beam and the portion not irradiated are located adjacently to each other, the irradiated portion functions as a core of the optical waveguide, while the non-irradiated portions located on both sides thereof (for example, on the right and left sides thereof; refer to a higher refractive index portion 3 a and a lower refractive index portion 3 b in FIG. 4( b ) which will be explained later) can function as cladding portions of the optical waveguide.
Therefore, when layers made of a resin that has a lower refractive index or layers that can reflect light (for example, metal layers) formed on the remaining sides (for example, an upper and lower sides) of the core, those layers can function as cladding layers, so that light can propagate within the core of the optical circuit forming layer, thereby resulting in the formation of an optical waveguide. In the first aspect, the light permeable resin layer can provide a cladding member on one (for example, a top side) side of the remaining sides of the core. Therefore, the refractive index of the light permeable resin layer must be lower than the refractive index of the optical circuit forming layer that has increased when irradiated with the activating energy beam. This relative relationship of the refractive indexes is not essential at a time before the irradiation of the activating energy beam. For example, at a time before the irradiation, the refractive index of the light permeable resin layer may be higher than the refractive index of the optical circuit forming layer. It is generally preferable that the refractive index of the light permeable resin layer does not substantially change by the irradiation, and is lower than the refractive index of the optical circuit forming layer.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention according to the first aspect, a core layer of the optical waveguide can be formed with the irradiated portion of the optical circuit forming layer and cladding layers can be formed with the non-irradiated portion of the optical circuit forming layer and with the light permeable resin layer by irradiating the optical circuit forming layer with the activating energy beam, while an electrical wiring can be formed by of metal layer processing (or a wiring pattern forming process), so that an optical circuit and an electrical circuit can be carried together by the same substrate, thus making it possible to manufacture the optical circuit-electrical circuit mixedly mounting substrate with the high quality in a simple method by using the conventional printed circuit board manufacturing technology.
In a second aspect, the present invention provides a material for an optical circuit-electrical circuit mixedly mounting substrate comprising:
a light permeable resin layer, and
an optical circuit forming layer that is made of a light permeable resin of which refractive index decreases when irradiated with an activating energy beam and is disposed adjacent to the light permeable resin layer,
wherein after the material for the optical circuit-electrical circuit mixedly mounting substrate with an activating energy beam so as to irradiate a portion of the optical circuit forming layer is irradiated, the refractive index of said portion is lower than that of the remaining non-irradiated portion of the optical circuit forming layer. The material for the optical circuit-electrical circuit mixedly mounting substrate is again a composite material as in the above wherein at least two layers are stacked, namely a laminate structure.
The material according to the second aspect has the light permeable resin layer and the optical circuit forming layer disposed adjacent thereto, while the optical circuit forming layer has a refractive index essentially higher than that of the light permeable resin layer and the optical circuit forming layer is made of a light permeable resin that decreases its refractive index when irradiated with the activating energy beam. When the activating energy beam is applied to the material for the optical circuit-electrical circuit mixedly mounting substrate so that a portion of the optical circuit forming layer is irradiated with the activating energy beam, the refractive index of the said portion of the optical circuit forming layer decreases to become lower than that of the rest of the optical circuit forming layer that has not been irradiated with the activating energy beam. Since the portion irradiated with the activating energy beam and the portion not irradiated are adjacent to each other, the non-irradiated portion can function as a core of the optical waveguide, while the irradiated portions located on both sides thereof (for example, on the right and left sides thereof; refer to a higher refractive index portion 4 a and a lower refractive index portion 4 b in FIG. 6( b ) which will be explained later) can function as cladding layers of the optical waveguide.
Therefore, layers made of a resin that has a low refractive index or layers that can reflect light (for example, metal layers) formed on the remaining sides (for example, the upper and lower sides) of the core can function as cladding layers, similarly to the material for the optical circuit-electrical circuit mixedly mounting substrate of the first aspect, so that light can propagate within the core of the optical circuit forming layer, thereby resulting in the formation of an optical circuit. In the second aspect, the light permeable resin layer has a refractive index lower than that of the optical circuit forming layer (even after the irradiation with the activating energy beam), and therefore can provide a cladding member on one (for example, a top side) of the remaining sides of the core.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention according to the second aspect, the core layer of the optical waveguide can be formed with the non-irradiated portion of the optical circuit forming layer and the cladding layers can be formed with the irradiated portion of the optical circuit forming layer and with the light permeable resin layer by irradiating the optical circuit forming layer with the activating energy beam, while an electrical wiring can be formed by metal layer processing so that an optical circuit and an electrical circuit can be formed together in the same substrate, thus making it possible to manufacture the optical circuit-electrical circuit mixedly mounting substrate with the high quality in a simple method by using the conventional printed circuit board manufacturing technology.
In a third aspect, the present invention provides a material for the optical circuit-electrical circuit mixedly mounting substrate characterized as follows:
In addition to the light permeable resin layer (referred to also as the first light permeable resin layer in order to distinguish it from a second light permeable resin layer described just below), the second light permeable resin layer is provided in the material for the optical circuit-electrical circuit mixedly mounting substrate of the first aspect as described above
wherein the optical circuit forming layer is disposed between the first light permeable resin layer and the second light permeable resin layer, and
after the activating energy beam is applied to the material for the optical circuit-electrical circuit mixedly mounting substrate so that a portion of the optical circuit forming layer is irradiated with the activating energy beam, a refractive index of said portion of the optical circuit forming layer is higher than that of the second light permeable resin layer.
The material for the optical circuit-electrical circuit mixedly mounting substrate is a composite material wherein at least three layers are stacked one on another, namely a laminate structure.
In the material according to the third aspect, the optical circuit forming layer is interposed between the first light permeable resin layer and the second light permeable resin layer. After the irradiation with the activating energy beam, since refractive index of the portion of the optical circuit forming layer irradiated with the activating energy beam is higher than those of the two light permeable resin layers, these resin layers can provide cladding portions for the portion of the optical circuit forming layer as the core which portion is irradiated with the activating energy beam.
As described above, after the irradiation of the activating energy beam, the refractive index of the second light permeable resin layer must be lower than the refractive index of the irradiated portion of the optical circuit forming layer that has been increased by the irradiation of the material for the optical circuit-electrical circuit mixedly mounting substrate with the activating energy beam. This relative relationship between the refractive indexes is not essential before the irradiation of the activating energy beam. For example, at a time before the irradiation, the refractive index of the second light permeable resin layer may be higher than the refractive index of the optical circuit forming layer. It is generally preferable that the refractive index of the second light permeable resin layer does not substantially change by the irradiation, and is lower than the refractive index of the optical circuit forming layer.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention according to the third aspect, the core layer of the optical waveguide can be formed with the irradiated portion of the optical circuit forming layer and the cladding layers can be formed with the non-irradiated portion of the optical circuit forming layer, the light permeable resin layer and with the second light permeable resin layer by irradiating the optical circuit forming layer with the activating energy beam, while an electrical wiring can be formed by metal layer processing so that an optical circuit and an electrical circuit can be formed together in the same substrate, thus making it possible to manufacture the optical circuit-electrical circuit mixedly mounting substrate with the high quality in a simple method by using the conventional printed circuit board manufacturing technology.
In a fourth aspect, the present invention provides a material for the optical circuit-electrical circuit mixedly mounting substrate characterized as follows:
In addition to the light permeable resin layer (referred to also as the first light permeable resin layer in order to distinguish it from a second light permeable resin layer described just below), the second light permeable resin layer is provided in the material for the optical circuit-electrical circuit mixedly mounting substrate of the second aspect as described above
wherein the optical circuit forming layer is disposed between the first light permeable resin layer and the second light permeable resin layer, and
after the activating energy beam is applied to the material for the optical circuit-electrical circuit mixedly mounting substrate so that a portion of the optical circuit forming layer is irradiated with the activating energy beam, a refractive index of the rest of the optical circuit forming layer is higher than that of the second light permeable resin layer.
The material for the optical circuit-electrical circuit mixedly mounting substrate is a composite material wherein at least three layers are stacked one on another, namely a laminate structure.
In the material according to the fourth aspect, the optical circuit forming layer is interposed between the first light permeable resin layer and the second light permeable resin layer. After the irradiation with the activating energy beam, since the refractive index of the portion of the optical circuit forming layer not irradiated with the activating energy beam is higher than those of the two light permeable resin layers, these resin layers can provide cladding portions for the portion of the optical circuit forming layer as the core which portion is not irradiated with the activating energy beam.
As described above, after the irradiation of the activating energy beam, the refractive index of the second light permeable resin layer must be lower than the refractive index of the portion of the optical circuit forming layer which portion has not been irradiated when the material for the optical circuit-electrical circuit mixedly mounting substrate is irradiated with the activating energy beam. This relative relationship between the refractive indexes is not essential before the irradiation of the activating energy beam. For example, upon the irradiation, the refractive index of the second light permeable resin layer may be decreased. It is generally preferable that the refractive index of the second light permeable resin layer does not substantially change by the irradiation, and is lower than the refractive index of the optical circuit forming layer.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention according to the fourth aspect, the core layer of the optical waveguide can be formed with the non-irradiated portion of the optical circuit forming layer and the cladding layers can be formed with the irradiated portion of the optical circuit forming layer, the light permeable resin layer and with the second light permeable resin layer by irradiating the optical circuit forming layer with the activating energy beam, while an electrical wiring can be formed by metal layer processing so that an optical circuit and an electrical circuit can be formed together in the same substrate, thus making it possible to manufacture the optical circuit-electrical circuit mixedly mounting substrate with the high quality in a simple method by using the conventional printed circuit board manufacturing technology.
In a fifth aspect, the present invention provides a material for the optical circuit-electrical circuit mixedly mounting substrate comprising:
a light permeable resin layer, and
an optical circuit forming layer that is made of a light permeable resin of which solubility to a solvent changes when irradiated with an activating energy beam and is disposed adjacent to the light permeable resin layer,
wherein after the activating energy beam is applied to the material for the optical circuit-electrical circuit mixedly mounting substrate so that a portion of the optical circuit forming layer is irradiated with the activating energy beam,
a refractive index of the optical circuit forming layer is higher than that of the light permeable resin layer;
said portion of the optical circuit forming layer irradiated with the activating energy beam changes from a state of being removable by dissolving into a solvent to a state of being insoluble; and
the rest of the optical circuit forming layer that is not irradiated with the activating energy beam remains in the state of being removable by dissolving into the solvent.
The material according to the fifth aspect has the light permeable resin layer and the optical circuit forming layer disposed adjacent thereto, while the optical circuit forming layer is made of a light permeable resin of which solubility to the solvent changes when irradiated with the activating energy beam. When the activating energy beam is applied to the material for the optical circuit-electrical circuit mixedly mounting substrate so that a portion of the optical circuit forming layer is irradiated with the activating energy beam, the irradiated portion of the optical circuit forming layer changes to the state of being insoluble into the solvent so that it is not removable by the solvent, and the rest of the optical circuit forming layer remains in the state of being removable by dissolving into a solvent.
In the fifth aspect, the expression that “solubility to solvent changes when irradiated with the activating energy beam” means that the resin that constitutes the optical circuit forming layer changes from the state of being soluble in a particular solvent to the state of being insoluble to the solvent when irradiated with the activating energy beam. Namely, it is meant that by irradiating a portion of the optical circuit forming layer with the activating energy beam, the particular portion is changed from the state of being removable by dissolving into a particular solvent to the state of being insoluble in the solvent and therefore cannot be removed (the portion that has not been irradiated is removable by dissolving into the solvent).
In the fifth aspect, at least after being irradiated with the activating energy beam, the refractive index of the optical circuit forming layer is higher than the refractive index of the light permeable resin layer, and these layers are disposed adjacently to each other. Thus when a portion of the optical circuit forming layer is left to remain as a core, the light permeable resin layer can provide a cladding member for the core. When a layer having a refractive index lower than the refractive index of the core is disposed on side(s) of the rest of the core (for example, on a right, left and lower sides thereof; refer to FIG. 2( b ) to be explained later), an optical waveguide surrounded by the materials each having lower refractive index can be formed.
According to the fifth aspect, a relative relationship between the refractive index of the optical circuit forming layer and the refractive index of the light permeable resin layer is not essential before the irradiation with the activating energy beam. For example, at a time before the irradiation, the refractive index of the light permeable resin layer may be higher than the refractive index of the optical circuit forming layer. It is generally preferable that the refractive indices of the optical circuit forming layer and the light permeable resin layer do not substantially change upon irradiation, and the refractive index of the optical circuit forming layer is higher than the refractive index of the light permeable resin layer.
In a sixth aspect, the present invention provides a material for the optical circuit-electrical circuit mixedly mounting substrate comprising:
a light permeable resin layer; and
an optical circuit forming layer that is made of a light permeable resin of which solubility to a solvent changes when irradiated with an activating energy beam and is disposed adjacent to the light permeable resin layer,
wherein, a refractive index of the optical circuit forming layer is higher than a refractive index of the light permeable resin layer; and
after the activating energy beam is applied to the material for the optical circuit-electrical circuit mixedly mounting substrate so that a portion of the optical circuit forming layer is irradiated with the activating energy beam,
said portion of the optical circuit forming layer irradiated with the activating energy beam changes from the state of not being removable by dissolving into a solvent to the state of being removable; and the rest of the optical circuit forming layer that has not been irradiated with the activating energy beam remains in the state of not being removable by dissolving into the solvent.
The material according to the sixth aspect has the light permeable resin layer and the optical circuit forming layer disposed adjacent thereto, while the optical circuit forming layer is made of a light permeable resin of which solubility to solvent changes when irradiated with the activating energy beam. When the activating energy beam is applied to the material for the optical circuit-electrical circuit mixedly mounting substrate so that a portion of the optical circuit forming layer is irradiated with the activating energy beam, the irradiated portion of the optical circuit forming layer changes to the state of being soluble in the solvent and removable, and the rest of the optical circuit forming layer remains in the state of not being removable by dissolving into the solvent.
In the sixth aspect, the expression that “solubility to solvent changes when irradiated with the activating energy beam” means that the resin that constitutes the optical circuit forming layer changes from the state of being not soluble in a particular solvent to the state of being soluble in the solvent when irradiated with the activating energy beam. Namely, it is meant that by irradiating a portion of the optical circuit forming layer with the activating energy beam, the particular portion is changed from the state of being not soluble in the particular solvent to the state of being soluble in the solvent and therefore can be removed (a portion that has not been irradiated is not removable by dissolving into the solvent).
In the sixth aspect, the refractive index of the optical circuit forming layer is intrinsically higher than the refractive index of the light permeable resin layer, and these layers are disposed adjacently to each other. Thus when a portion of the optical circuit forming layer is left to remain as a core by not dissolving into the solvent and not removing thereby, the light permeable resin layer can provide a cladding portion for the core. When a layer having refractive index lower than the refractive index of the core is disposed on the side of the rest of the core (for example, on a right side, a left side and a lower side thereof), an optical waveguide surrounded by the materials having a lower refractive index can be formed.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention according to the fifth and sixth aspects, the core layer of the optical waveguide can be formed with the optical circuit forming layer and the cladding layer of the optical waveguide can be formed with the light permeable resin layer by irradiating the optical circuit forming layer with the activating energy beam followed by developing, while electrical wiring can be formed by metal layer processing so that an optical circuit and an electrical circuit can be formed together on the same circuit board, thus making it possible to manufacture the optical circuit-electrical circuit mixedly mounting substrate of the high quality with a simple method by using the conventional printed circuit board manufacturing technology.
In a seventh aspect, the present invention provides the following material for the optical circuit-electrical circuit mixedly mounting substrate:
In the material for the optical circuit-electrical circuit mixedly mounting substrate according to any one of the first to sixth aspects, it further comprises a metal layer, and the light permeable resin layer is disposed between the metal layer and the optical circuit forming layer.
The material for the optical circuit-electrical circuit mixedly mounting substrate of the seventh aspect is further provided with the metal layer. The metal layer is disposed on the side of the light permeable resin layer (namely, the first light permeable resin layer) which side is opposite to the side thereof to which the optical circuit forming layer is adjacent. The metal layer can constitute an electric circuit (including an electronic circuit) or an electric wiring layer by leaving a predetermined portion thereof to remain by an appropriate process. The metal layer can be of any proper form, such as foil, film, sheet or the like.
In an eighth aspect, the present invention provides a material for an optical circuit-electrical circuit mixedly mounting substrate comprising:
a metal layer, and
an optical circuit forming layer that is made of a light permeable resin of which refractive index increases when irradiated with an activating energy beam and is disposed adjacent to the metal layer,
wherein the refractive index of a portion of the optical circuit forming layer is higher than that of the rest of the optical circuit forming layer that is not irradiated with the activating energy beam after the material for the optical circuit-electrical circuit mixedly mounting substrate is irradiated with an activating energy beam so that said portion of the optical circuit forming layer is irradiated.
The material for the optical circuit-electrical circuit mixedly mounting substrate is a composite material wherein at least two layers are stacked, namely a laminate structure.
The material for the optical circuit-electrical circuit mixedly mounting substrate according to the eighth aspect is different from the material for the optical circuit-electrical circuit mixedly mounting substrate of the first aspect in that the metal layer is used instead of the light permeable resin layer. The optical circuit forming layer may be the same as the optical circuit forming layer in the material for the optical circuit-electrical circuit mixedly mounting substrate of the first aspect.
The material according to the eighth aspect has the light permeable resin layer and the metal layer adjoining thereto, and the optical circuit forming layer is made of a light permeable resin of which refractive index increases when irradiated with the activating energy beam. When the activating energy beam is applied to the material for the optical circuit-electrical circuit mixedly mounting substrate so that a portion of the optical circuit forming layer is irradiated with the activating energy beam, the refractive index of the irradiated portion of the optical circuit forming layer increases to be higher than that of the non-irradiated portion. Since the portion irradiated with the activating energy beam and the portion not irradiated are adjacent to each other, the irradiated portion can function as the core of the optical waveguide, while the non-irradiated portions located on both sides thereof (for example, on a right and left sides thereof) can function as cladding layers of the optical waveguide, similarly to the case of the material for the optical circuit-electrical circuit mixedly mounting substrate of the first aspect.
Therefore, layers made of a resin that has a lower refractive index or layers that reflects light (for example, metal layers) formed on the remaining surfaces (for example, an upper side and a lower side) of the core can function as cladding layers or reflectors, so that light can propagate within the core of the optical circuit forming layer. In the eighth aspect, the metal layer can provide a reflector layer on one (for example, a top side) of the remaining sides of the core.
In a ninth aspect, the present invention provides a material for an optical circuit-electrical circuit mixedly mounting substrate comprising:
a metal layer, and
an optical circuit forming layer that is made of a light permeable resin of which refractive index decreases when irradiated with an activating energy beam and is disposed adjacently to the metal layer,
wherein after the material for the optical circuit-electrical circuit mixedly mounting substrate is irradiated with the activating energy beam on a portion of the optical circuit forming layer, the refractive index of said portion of the optical circuit forming layer irradiated with the activating energy beam is lower than that of the rest of the optical circuit forming layer that is not irradiated with the activating energy beam.
The material for the optical circuit-electrical circuit mixedly mounting substrate is a composite material wherein at least two layers stacked one on another, namely a laminate structure.
The material for the optical circuit-electrical circuit mixedly mounting substrate according to the ninth aspect is different from the material for the optical circuit-electrical circuit mixedly mounting substrate of the second aspect in that the metal layer is used instead of the light permeable resin layer. The optical circuit forming layer itself may be the same as the optical circuit forming layer of the material for the optical circuit-electrical circuit mixedly mounting substrate of the second aspect.
The material according to the ninth aspect has the light permeable resin layer and the metal layer adjoining thereto, and the optical circuit forming layer is made of a light permeable resin of which refractive index increases when irradiated with the activating energy beam. When the activating energy beam is applied to the material for the optical circuit-electrical circuit mixedly mounting substrate so that a portion of the optical circuit forming layer is irradiated with the activating energy beam, the refractive index of the irradiated portion of the optical circuit forming layer decreases to be lower than that of the non-irradiated portion. Since the portion irradiated with the activating energy beam and the portion not irradiated are adjacent to each other, the irradiated portion can function as the core of the optical waveguide, while the non-irradiated portions located on both sides of the core (for example, on a right and left sides thereof; refer to a higher refractive index portion 5 a and a lower refractive index portion 5 b in FIG. 8( b ) to be explained later) can function as cladding layers of the optical waveguide.
Therefore, layers made of a resin that has a lower refractive index or layers that can reflect light (for example, metal layers) formed on the remaining sides (for example, an upper side and a lower side) of the core can function as cladding layers or reflectors, so that light can propagate within the core of the optical circuit forming layer. In the ninth aspect, the metal layer can provide a reflector layer on one (for example, a top side) of the remaining sides of the core.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention according to the eighth and ninth aspects, the core layer of the optical waveguide can be formed with one of the irradiated portion and the non-irradiated portion of the optical circuit forming layer, and the cladding layer can be formed with the other one of the irradiated portion and non-irradiated portion of the optical circuit forming layer by irradiating the optical circuit forming layer with the activating energy beam, while electrical wiring can be formed by processing of the metal layer so that an optical circuit and an electrical circuit can be formed together on the same circuit board, thus making it possible to manufacture the optical circuit-electrical circuit mixedly mounting substrate with the high quality with a simple method by using the conventional printed circuit board manufacturing technology.
In a tenth aspect, the present invention provides a material for the optical circuit-electrical circuit mixedly mounting substrate characterized as follows:
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the eighth aspect, a light permeable resin layer is further provided, and the optical circuit forming layer is disposed between the metal layer and the light permeable resin layer and, when the activating energy beam is applied to the material for the optical circuit-electrical circuit mixedly mounting substrate so that a portion of the optical circuit forming layer is irradiated with the activating energy beam, the refractive index of said portion of the optical circuit forming layer is higher than that of the second light permeable resin layer after the irradiation.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the tenth aspect, similarly to the material for the optical circuit-electrical circuit mixedly mounting substrate of the eighth aspect, the metal layer provides a reflector layer, while the light permeable resin layer has a refractive index lower than that of the said portion at least after the irradiation with the activating energy beam or preferably regardless of whether before or after the irradiation, and is disposed to oppose the metal layer via the optical circuit forming layer. Therefore, the light permeable resin layer can provide a cladding member for said portion of the optical circuit forming layer which portion serves as the core.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention according to the tenth aspect, the core layer of the optical waveguide can be formed with the irradiated portion of the optical circuit forming layer and the cladding layers can be formed with the non-irradiated portion of the optical circuit forming layer and with the light permeable resin layer by irradiating the optical circuit forming layer with the activating energy beam, while an electrical wiring can be formed by metal layer processing so that an optical circuit and an electrical circuit can be formed together on the same circuit board, thus making it possible to manufacture the optical circuit-electrical circuit mixedly mounting substrate with the high quality with a simple method by using the conventional printed circuit board manufacturing technology.
In an eleventh aspect, the present invention provides a material for the optical circuit-electrical circuit mixedly mounting substrate characterized as follows:
In the material for the optical circuit-electrical circuit mixedly mounting substrate according to the ninth aspect, the material for the optical circuit-electrical circuit mixedly mounting substrate, a light permeable resin layer is further provided, and the optical circuit forming layer is disposed between the metal layer and the light permeable resin layer and,
when the activating energy beam is applied to the material for the optical circuit-electrical circuit mixedly mounting substrate so that a portion of the optical circuit forming layer is irradiated with the activating energy beam, the refractive index of the rest of the optical circuit forming layer that has not been irradiated with the activating energy is higher than that of the light permeable resin layer after the irradiation.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the eleventh aspect, similarly to the material for the optical circuit-electrical circuit mixedly mounting substrate of the ninth aspect, the metal layer can provide a reflector layer while the light permeable resin layer has refractive index lower than that of the rest of the optical circuit forming layer at least after the irradiation with the activating energy beam or preferably regardless of whether before or after the irradiation, and is disposed to oppose the metal layer via the optical circuit forming layer. Therefore, the light permeable resin layer provides cladding portions for the remaining portion that serves as the core.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention according to the eleventh aspect, the core layer of the optical waveguide can be formed with the non-irradiated portion of the optical circuit forming layer and the cladding layers can be formed with the irradiated portion of the optical circuit forming layer and with the light permeable resin layer by irradiating the optical circuit forming layer with the activating energy beam, while electrical wiring can be formed by metal layer processing so that an optical circuit and an electrical circuit can be formed together on the same substrate, thus making it possible to manufacture the optical circuit-electrical circuit mixedly mounting substrate of the high quality with a simple method by using the conventional printed circuit board manufacturing technology.
In a twelfth aspect, the present invention provides the following material for the optical circuit-electrical circuit mixedly mounting substrate:
the material for the optical circuit-electrical circuit mixedly mounting substrate of any one of the seventh to the eleventh aspects wherein an adhesive layer is provided adjacent to the metal layer and the adhesive layer is disposed between the metal layer and the optical circuit forming layer.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of this aspect, the metal layer is provided on the optical circuit forming layer or the light permeable resin layer by using the adhesive layer interposed therebetween. This constitution improves the bonding between the metal layer and the optical circuit forming layer or the light permeable resin layer. The adhesive layer adjoins the metal layer on one side thereof, and adjoins the optical circuit forming layer or the light permeable resin layer on the other side.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention according to the twelfth aspect, bonding strength of the electrical wiring to be formed can be increased by the adhesive layer, thereby improving the reliability of the electrical wiring.
In a thirteenth aspect, the present invention provides the following material for the optical circuit-electrical circuit mixedly mounting substrate:
The material for the optical circuit-electrical circuit mixedly mounting substrate of any one of the seventh to twelfth aspects wherein a supporting member is further provided, the supporting member constituting an exposed surface of the material for the optical circuit-electrical circuit mixedly mounting substrate on the side thereof nearer to the metal layer.
In this specification, the phrase “nearer to (or farther from)” is used to mean that the number of layers interposed between the layers in question is smaller (or larger), and does not based on the actual distance between those layers.
The supporting member is preferably stacked on the metal layer, so as to provide mechanical strength to the material for the optical circuit-electrical circuit mixedly mounting substrate thereby making it easier to handle the material for the optical circuit-electrical circuit mixedly mounting substrate. The supporting member is preferably processed on one side thereof to be readily peeled off (namely a releasable supporting member), so as to be detached from the material for the optical circuit-electrical circuit mixedly mounting substrate thereby exposing the metal layer as required. The supporting member may be made of any material as long as it can provide the mechanical strength, and it may be for example a plastic or metal sheet.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention according to the thirteenth aspect, the metal layer can be reinforced by the supporting member, so as to improve the ease of handling during the process such as providing a resin layer on the metal layer.
In a fourteenth aspect, the present invention provides the following material for the optical circuit-electrical circuit mixedly mounting substrate:
The material for the optical circuit-electrical circuit mixedly mounting substrate of any one of the seventh through thirteenth aspects wherein a cover film is further provided, the cover film constituting a surface of the material for the optical circuit-electrical circuit mixedly mounting substrate on the side thereof farther from the metal layer.
The cover film constitutes at least one of the exposed surfaces of the material for the optical circuit-electrical circuit mixedly mounting substrate, and preferably constitutes the exposed surface of the material for the optical circuit-electrical circuit mixedly mounting substrate on the side thereof farther from the metal layer. In other words, the cover film constitutes the surface of the material for the optical circuit-electrical circuit mixedly mounting substrate opposite to the surface constituted by the supporting member. The cover film may or may not be permeable to light. In the case wherein the cover film is permeable to light, the material for the optical circuit-electrical circuit mixedly mounting substrate can be irradiated with the activating energy beam even when the cover film is present. The cover film is preferably made of a resin, and a transparent film such as a polyester film, a polypropylene film, a polyethylene film or a polyacetate film can be used. While there is no limitation as to the thickness of the cover film, the thickness in the range from 5 to 100 μm is preferably employed. A surface of the cover film may be processed so as to allow easy release.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention according to the fourteenth aspect, the resin layer can be protected by the cover film, so as to improve the ease of handling of the material for the optical circuit-electrical circuit mixedly mounting substrate.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of any of the aspects described above, it is preferable that the optical circuit forming layer can minimize the light that escapes from the core formed therein to the outside, namely minimize the optical loss. For that purpose, a light transmissivity of the optical circuit forming layer is preferably 0.2 dB/cm or lower, and more preferably 0.1 dB/cm or lower. While this value of the light transmissivity is for the state after being irradiated with the activating energy beam, the light transmissivity is preferably at a similar level also before the irradiation.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention described above, the resin that can be used to form the light permeable resin layer (namely the first light permeable resin layer) may be any proper light permeable resin (or transparent resin) known to those skilled in the art in the formation of the optical waveguide, particularly the formation of the cladding member of the optical waveguide. Preferable materials of such light permeable resin may be exemplified by the following:
Photocurable resin that is cured by light or UV (for example, Optodyne UV-3100 manufactured by Daikin Industries, Ltd.); and
Thermosetting resin (for example, epoxy resin, polyimide resin, unsaturated polyester resin, epoxy acrylate resin, etc.)
For the purpose of flame resistance and/or absorbency for the activating energy beam, such a resin may contain an additive or reactive flame retardant and/or an ultraviolet absorber based on halogen, phosphorus or silicon compound. Those resins may be used also to form other light permeable resin layer such as the second light permeable resin layer.
For the resin of which refractive index changes when irradiated with the activating energy beam (which will be also referred to as a “photosensitive resin” for convenience in this specification since the refractive index of such a resin changes when exposed to light in its broader sense of the word), any proper resin known to those skilled in the art that can be used, exemplified by the following preferable materials:
(i) Resin of which refractive index increases when irradiated with the activating energy beam:
“Polyguide” manufactured by DuPont, acrylic resin containing a photopolymerizable monomer, etc.; and
(ii) Resin of which refractive index decreases when irradiated with the activating energy beam:
Polysilane (for example, polymethylphenylsilane), a composite resin in which a photopolymerizable acrylic monomer is contained in a polycarbonate resin dissolved in a solvent (a film made of this resin is irradiated and then acrylic monomer is removed by evaporation in vacuum), etc.
For the resin of which solubility to solvent changes when irradiated with the activating energy beam (which will be also referred to as a “photosensitive resin” for convenience in this specification since the solubility of such a resin to the solvent changes when exposed to light in its broader sense of the word), any proper resin known to those skilled in the art that can be used, exemplified by the following preferable materials:
(i) Resin which becomes substantially soluble in a solvent when irradiated with the activating energy beam:
Photolytic resin (naphthoquinone-based resin, etc.)
(ii) Resin which becomes substantially insoluble in a solvent when irradiated with the activating energy beam:
Photocurable resin (acrylic resin, epoxy resin, polyimide resin, silicon-based resin), and electron radiation curable resin (acrylic resin, epoxy resin, polyimide resin, etc.)
These resins must be selected so that the layer formed therewith satisfies the relationship of the refractive index described previously at least after being irradiated with the activating energy beam. The selection may be done by those skilled in the art in accordance to such factors as the dimensions (length, width, etc.) of the waveguide to be formed (with the core and the cladding portion or the reflector), and a type of a optical signal to propagate therein (especially its wavelength, transmission rate, etc.). With regard to the refractive index, for example, the resins that constitute the layers are selected so that the refractive index of the core is higher than the refractive index of the cladding portion by at least about 0.1%, preferably at least about 0.2% and more preferably at least about 1%.
The layers may be formed from the selected resins by any proper method, and a method commonly employed in the field of manufacturing printed circuit boards may be used.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention described above, the adhesive that can be preferably used to form the adhesive layer may be thermosetting resins such as epoxy resin, polyimide resin, unsaturated polyester resin and epoxy acrylate resin. The adhesive may contain a flame retardant based on halogen, phosphorus or silicon compound so as to make it flame resistant, and may also contain an ultraviolet absorber.
In the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention described above, the metal layer may be formed from any metal commonly used to form a wiring layer in the manufacture of the printed circuit boards, such as copper, aluminum, or nickel. For example, a copper foil may be used. The metal layer may be formed by plating, vapor deposition, sputtering or the like.
When irradiating the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention with the activating energy beam, the activating energy beam may be applied on either side of the material for the optical circuit-electrical circuit mixedly mounting substrate as long as the optical circuit forming layer can be irradiated with the activating energy beam and the relationship of refractive indices is satisfied. In the case wherein the material for the optical circuit-electrical circuit mixedly mounting substrate has the metal layer, the optical circuit forming layer is irradiated on the side thereof opposite to the metal layer, since the metal layer reflects the activating energy beam.
In a fifteenth aspect, the present invention provides a method for manufacturing an optical circuit-electrical circuit mixedly mounting substrate comprising the steps of:
(1) applying an activating energy beam to the material for the optical circuit-electrical circuit mixedly mounting substrate that comprises at least an optical circuit forming layer so as to form a core of an optical waveguide in the optical circuit forming layer, wherein the optical circuit forming layer is made of a light permeable resin of which solubility to solvent changes or of which refractive index changes when irradiated with the activating energy beam;
(2) forming a light deflecting portion in the core;
(3) bonding a metal layer onto the material for the optical circuit-electrical circuit mixedly mounting substrate; and
(4) processing the metal layer to form an electrical circuit.
In the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate of the present invention according to the fifteenth aspect, such a material for the optical circuit-electrical circuit mixedly mounting substrate is used in the process (1) which material has at least the optical circuit forming layer made of a light permeable resin of which solubility to solvent changes or of which refractive index changes when irradiated with the activating energy beam. In the material for the optical circuit-electrical circuit mixedly mounting substrate, the optical circuit forming layer made of the light permeable resin of which solubility to solvent changes when irradiated with the activating energy beam and the optical circuit forming layer made of the light permeable resin of which refractive index changes when irradiated with the activating energy beam are those described previously in conjunction with the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention, and those optical circuit forming layers allow to form the core in the irradiated portion or in the non-irradiated portion, depending on the material used to constitute the optical circuit forming layer, when the optical circuit forming layer is irradiated by applying the activating energy beam to the material for the optical circuit-electrical circuit mixedly mounting substrate.
Thus the core of the waveguide through which light propagates is formed in a predetermined portion of the optical circuit forming layer, by irradiating the predetermined portion of the optical circuit forming layer with the activating energy beam. In the case of the optical circuit forming layer of which solubility to solvent changes, it is necessary to remove the portions other than that where the core is to be formed, by dissolving to the solvent.
In step (2), the light deflecting portion is formed in the core that has been formed. The “light deflecting portion” refers to a component that changes a propagating direction of at least a portion of light propagating through the core so that said portion of light propagates in a different direction so as to emerge out of the core, or changes a propagating direction of at least a portion of light injected into the core from its outside in a different direction so that said portion of light propagates through the core. Such “light deflecting portion” is referred to as a deflector or coupler. In other words, the light deflecting section is a component that causes light propagating in an optical waveguide having the core to emerge out of the waveguide, or causes light to enter from the outside of the optical waveguide into the optical waveguide. The light deflecting portion may be formed in any appropriate position in the core, and is formed in, for example, at an end of the core (that is usually elongated), at an intermediate position or the like. The light deflecting section may extend over at least a portion or over the entire of thickness (in the direction perpendicular to the light propagating direction) of the core. The light deflecting portion may also extend outside the thickness and/or width of the core, as required.
Then, in the step (3), the metal layer is bonded onto the material for the optical circuit-electrical circuit mixedly mounting substrate in which the core has been formed. The metal layer may be the same as the metal layer described previously in conjunction with the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention. For example, the metal layer is a metal foil, a metal film, a metal sheet or the like. The metal layer may be bonded via an adhesive layer in the material for the optical circuit-electrical circuit mixedly mounting substrate.
In step (4), the electrical circuit is formed by processing the bonded metal layer by a proper method so that the metal remains in a predetermined pattern. The electrical circuit may be formed by any method commonly used to form a wiring layer from a metal layer in the manufacture of printed circuit boards.
In a sixteenth aspect, the present invention provides the following method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate:
In the method according to the fifteenth aspect, the material for the optical circuit-electrical circuit mixedly mounting substrate of any one of the first through sixth aspects is used as the material for the optical circuit-electrical circuit mixedly mounting substrate.
The material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention described previously can be preferably used in the manufacturing method according to the fifteenth aspect.
In a seventeenth aspect, the present invention provides a method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate comprising the steps of:
(1) applying the activating energy beam to the optical circuit forming layer of the material for the optical circuit-electrical circuit mixedly mounting substrate that has at least the metal layer and the optical circuit forming layer so as to form the core of the optical waveguide in the optical circuit forming layer, wherein the optical circuit forming layer is made of a light permeable resin of which solubility to solvent changes or of which refractive index changes when irradiated with the activating energy beam;
(2) forming a light deflector portion; and
(3) processing the metal layer to form an electrical circuit.
The method for manufacturing the optical-electrical hybrid circuit board of the present invention according to the seventeenth aspect is different from the manufacturing method of the fifteenth aspect in that the material for the optical circuit-electrical circuit mixedly mounting substrate, as a laminate structure is used which substrate comprises at least the metal layer and the optical circuit forming layer made of the light permeable resin of which solubility to solvent changes or of which refractive index changes when irradiated with the activating energy beam, and that as a result, the step of bonding the metal layer is not necessary. With the other respects, this manufacturing method is similar to the method of the fifteenth aspect.
In an eighteenth aspect, the present invention provides the following method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate:
In the method according to the seventeenth aspect, wherein the material for the optical circuit-electrical circuit mixedly mounting substrate of any one of the seventh to thirteenth aspects is used as the material for the optical circuit-electrical circuit mixedly mounting substrate.
The material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention described previously can be preferably used in the manufacturing method according to the seventeenth aspect.
In the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate of the present invention according to the fifteenth to eighteenth aspects, it is made possible to manufacture the optical circuit-electrical circuit mixedly mounting substrate with the high quality in a simple method by using the conventional printed circuit board manufacturing technology, without requiring steps for stacking a cladding layer, a core layer and a further cladding layer on a substrate and/or forming an electrical circuit by plating as in the prior art.
In a nineteenth aspect, the present invention provides the following method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate:
In the method according to the seventeenth or eighteenth aspect, a core of the optical waveguide, a deflector portion and an electrical circuit are formed at predetermined positions based on a reference mark formed in advance on the metal layer of the material for the optical circuit-electrical circuit mixedly mounting substrate.
With this manufacturing method, the reference mark is previously formed on the metal layer, and the position to irradiate with the activating energy beam is determined on the basis of positional relationship with the reference mark during the manufacture of the optical circuit-electrical circuit mixedly mounting substrate. For example, a mask used upon the irradiation is located with reference to the reference mark. The position to form the deflector portion is also determined on the basis of the positional relationship with the reference mark. The position to form the electrical circuit is also determined on the basis of the positional relationship with the reference mark. As the core, the deflector portion and the electrical circuit are formed using the same reference mark formed on the metal layer, the positional relationships between these components are also established as predetermined. The reference mark may be of any form that can serve the purpose, and for example, two rectangles measuring 100 μm by 500 μm crossing each other at their centers to form a cross-shape.
According to the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate of the nineteenth aspect, the optical waveguide, the deflector portion and the electrical circuit are aligned with each other by means of the reference mark, so that the optical waveguide, the deflector portion and the electrical circuit can be formed with good precision.
In a twentieth aspect, the present invention provides the following method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate:
In the method according to any one of the fifteenth to the eighteenth aspects, the reference mark is formed on the optical circuit forming layer at the same time as it is irradiated with the activating energy beam, and then the deflector portion and the electrical circuit are formed at predetermined positions with reference to the reference mark in process (1) of forming the core.
According to this manufacturing method, when the core is formed by the irradiation with the activating energy beam, the irradiation results in the formation of the reference mark as well as the core. The mark has substantially the same refractive index as that of the core, but is different from the core in that it does not have the purpose of propagating light and is intended simply to rest at the predetermined position.
The manufacturing method of the twentieth aspect makes it possible to form the reference mark simultaneously in the step of forming the core of the optical waveguide, which simplifies the step of forming the reference mark, and form the core of the optical waveguide and the reference mark in the optical circuit forming layer with good accuracy of the positional relationship in the step of the exposure to the activating energy beam, thereby forming the deflector portion and the electrical circuit with the good positional accuracy in relation to the core of the optical guide by using the reference mark.
In a twenty-first aspect, the present invention provides the following method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate:
In the method according to any one of the fifteenth through twentieth aspects, before the electrical circuit forming step (4) or (3), a substrate is bonded onto a surface of the material for the optical circuit-electrical circuit mixedly mounting substrate which surface is opposite to a surface thereof on which surface the electrical circuit is formed.
According to this manufacturing method, after the step (1) of forming the core of the optical waveguide and the step (2) of forming the deflector portion, the surface where the core has been formed is bonded onto the substrate and then the electrical circuit is formed. While the substrate may be made of any proper material, preferably it provides mechanical strength, namely rigidity, with the material for the optical circuit-electrical circuit mixedly mounting substrate. For example, a glass-epoxy plate, a glass plate or a metal plate may be used.
The manufacturing method of the twenty-first aspect makes it possible to form an electrical circuit on the material for the optical circuit-electrical circuit mixedly mounting substrate that has been made rigid by bonding onto the substrate, thus improving the efficiency upon the formation of the electrical circuit.
In a twenty-second aspect, the present invention provides the following method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate:
In the method according to the twenty-first aspect, the substrate is a wiring board, preferably a printed circuit board that has an electrical circuit (referred to as the second electrical circuit in order to distinguish from the electrical circuit (first electrical circuit) formed from the metal layer) formed on the surface and/or inside thereof, and the method further comprises the step of electrically connecting the second electrical circuit and the formed first electrical circuit.
In this manufacturing method, the wiring board may be of any appropriate type, and for example a printed circuit board. The wiring board may be either a double-sided wiring board or a multi-layered wiring board. This manufacturing method is capable of easily manufacture the optical circuit-electrical circuit mixedly mounting substrate of a multi-layered structure.
In a twenty-third aspect, the present invention provides the following method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate:
In the method according to the twenty-first or twenty-second aspect, the step of bonding the wiring board via an adhesive layer is included, and the adhesive layer has a refractive index lower than that of the core.
According to this manufacturing method, the adhesive layer is formed from the adhesive used in the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention described previously, namely a thermosetting resin, for example, an epoxy resin, a polyimide resin, an unsaturated polyester resin or an epoxy acrylate resin, that is controlled to have a refractive index lower than that of the core. This adhesive layer can be used as the cladding portion for the core because of the relationship of the refractive indexes. As a result, the step of forming the cladding portion can be eliminated so as to simplify the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate.
In a twenty-fourth aspect, the present invention provides the following method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate:
In the method according to one of the fifteenth to twenty-third aspects, the material for the optical circuit-electrical circuit mixedly mounting substrate further comprises a cover film that constitutes an exposed surface on a side of the material for the optical circuit-electrical circuit mixedly mounting substrate which side is opposite to the side on which the metal layer of the optical circuit forming layer is provided, or an exposed surface of a side of the material for the optical circuit-electrical circuit mixedly mounting substrate which side is opposite to the side to which the metal layer of the material for the optical circuit-electrical circuit mixedly mounting substrate is bonded, and the step (2) of forming the deflector portion is carried out by forming a surface that is inclined with respect to the light propagating direction in the core with the cover film in place, then forming a light reflector on the inclined surface and then peeling off the cover film.
This manufacturing method makes it possible to form the deflector portion while protecting the optical circuit forming layer with the cover film by using the cover film as a mask. The cover film may or may not be transparent depending on the purpose.
In a twenty-fifth aspect, the present invention provides the following method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate:
In the method according to one of the fifteenth to twenty-fourth aspects, a surface that is inclined with respect to the light propagating direction is formed at least on the core, and the light reflector is formed by applying a paste containing metal particles to the inclined surface, thereby forming the deflector portion.
According to this manufacturing method, the inclined surface of the deflector portion is inclined with respect to the longitudinal direction of the core, namely the optical axis of the waveguide. There is no restriction on the angle of inclination, which may be, for example, 45° with respect to the longitudinal direction of the core in which case the light propagating direction is deflected by 90°. When forming the light reflector on the deflector portion by using the paste, a light reflecting portion or a reflector member having a reflecting surface can be formed without using a massive vacuum apparatus as in the case of the vapor deposition of metal.
The light reflector of the deflector portion may also be formed by the vapor deposition of metal onto the inclined surface, in which case a light reflector that is uniform and has a high purity can be formed easily.
In a twenty-sixth aspect, the present invention provides the following method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate:
In the method according to any one of the fifteenth to twenty-fifth aspects, a portion of the metal layer that opposes the deflector portion (for example, located above the deflector portion) is removed in the step (4) or (3) of forming the electrical circuit, and then a light permeable resin is applied to the portion from which the metal layer has been removed.
According to this manufacturing method, a portion of the metal layer located in the path from the inside of the core through the deflector section to the outside of the core (namely located in the optical propagating direction or optical axis), which will be referred to as a “portion of the metal layer opposing the deflector portion”, is removed. In the case wherein light is extracted from the deflector portion in a direction 90° upward from the longitudinal direction of the core, for example, a portion of the metal layer located right above the deflector portion is removed. When light is extracted at other angle, for example, a portion of the metal layer located obliquely above the deflector section is removed. In the case wherein light is introduced from the outside of the core through the deflector portion into the core, the portion of the metal layer to be removed can be easily determined by reversing the consideration described above.
With this method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate, even when a base layer exposed by removing the metal layer has a rough surface, light introduced into the deflector portion or light emerging from the deflector portion can be prevented from being scattered by coating the rough surface with the light permeable resin, thereby to prevent the optical coupling efficiency between the optical waveguide and the outside from decreasing.
In one preferable form, the light permeable resin is applied in the form of a convex lens. This enables the applied resin to collect light entering or emerging from the deflector portion, so as to more effectively prevent the optical coupling efficiency between the optical waveguide and the outside from decreasing.
It is preferable that the light permeable resin applied has a refractive index which is the same as or similar to that of the resin that is exposed by removing the metal layer. This enables it to decrease the reflection loss due to the difference in the refractive indexes between both resins, thereby improving the optical coupling efficiency between the optical waveguide and the outside.
When the light permeable resin is applied, a portion of the metal layer in a region opposing the deflector portion is removed, then a surface and an end surface (or side surface) of the metal layer that remains around the removed area are treated to become water-repellent, and the light permeable resin is applied thereafter. This reduces the influence on the shape of the light permeable resin, that has been applied in dropwise, caused by the minute unevenness of the area from which the metal has been removed, thereby enabling it to form the light permeable resin in a stable shape.
Such water-repellent treatment is preferably to coat the surface and the end surfaces of the metal layer that remains around the removed area thereof with a polymer film 244 having a low surface energy density. In this case, the water-repellent treatment can be easily carried out by for example spraying only the desired area.
In a twenty-seventh aspect, the present invention provides the following method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate:
In the method according to any one of the fifteenth to twenty-fifth aspects, a portion of the metal layer that opposes the deflector portion (for example, located above the deflector portion) is removed when forming the electrical circuit, and then a lens is placed in the portion from which the metal layer has been removed so as to make contact with the remaining metal layer that surrounds the portion so that the optical axis of the lens passes through the deflector portion.
This method is the same as the method of the twenty-sixth aspect with regard to the portion of the metal layer that opposes the deflector section. Such portion of the metal layer is removed and the lens is placed in the place where the metal layer is removed. The lens may be of any shape that can collect light, and for example, a ball lens or a half-ball lens. According to this manufacturing method, light entering or emerging from the deflector portion can be collected by the lens, so as to more effectively prevent the optical coupling efficiency between the optical waveguide and the outside from decreasing.
It is preferable to remove the portion of the metal layer so that the optical axis of the lens passes through the deflector portion when the lens is placed so as to make contact with the remaining metal layer that surrounds the portion. In this case, the lens can be placed at a precise position easily with high accuracy by fitting the lens in the portion from which the metal has been removed, which also makes it easy to place a plurality of lenses with less positional deviation.
The lens is preferably a ball lens or a ball lens of which portion is made flat. A ball lens or a half-ball lens that is commercially available can be used as it is, and can be easily mounted on the portion from which the metal has been removed.
When mounting the lens, it is preferable to apply a light permeable resin to fill the gap between the surface of the portion from which the metal has been removed and the lens. This reduces the reflection loss caused by a layer of air formed between the surface of the portion from which the metal has been removed and the lens, and firmly fixes the lens by means of the light permeable resin. For the light permeable resin, the light permeable resin used in the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention described previously can be used.
It is preferable that the light permeable resin used to fill the gap has a refractive index which is the same as or similar to that of the resin which is exposed by removing the metal layer. As a result, reflection loss due to the difference in refraction indexes between both resins can be reduced and the optical coupling efficiency between the optical waveguide and the outside can be improved.
In a twenty-eighth aspect, the present invention provides the following method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate:
In the method according to any one of the fifteenth to twenty-seventh aspects, such an optical circuit-electrical circuit mixedly mounting substrate is used that has a light permeable resin layer which has a refractive index lower than that of the core and is formed between the optical circuit forming layer and the metal layer or formed on a surface of the optical circuit forming layer on a side thereof where the metal layer is bonded.
According to this method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate, the light permeable resin layer and the optical circuit forming layer are adjacent to each other in the material for the optical circuit-electrical circuit mixedly mounting substrate or the optical circuit forming layer are adjacent to each other in the material for the optical circuit-electrical circuit mixedly mounting substrate.
The optical circuit forming layer may be the optical circuit forming layer described previously in conjunction with the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention. This manufacturing method enables it to prevent the core from making direct contact with the metal layer, so as to obtain the optical circuit-electrical circuit mixedly mounting substrate of the high quality by eliminating the causes of light transmission loss.
According to the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate of the present invention, the deflector portion may be formed in a step that includes the step of forming a surface 7 that is inclined with respect to the light propagating direction at least in the optical circuit forming layer and the step of forming the light reflector on the surface of the inclined surface. This makes it easy to form the deflector portion by forming the inclined surface and the light reflector.
When the surface inclined with respect to the light propagating direction is formed at least on the optical circuit forming layer, it is preferably formed by a cutting operation using a rotary blade or cutting tool having a cutting edge of which apex angle is about 90° or of which apex angle of at least one side is 45°. In this case, a surface inclined at an angle of 45° that allows it to eject or enter light at a deflection angle of about 90° can be formed by the cutting operation with high angular accuracy and good reproducibility. The deflector portion, particularly the inclined surface thereof may be formed by the other processing method, for example ultraviolet laser machining, instead of using the blade.
Such a cutting operation can be carried out by bringing the rotary blade or cutting tool into contact with the optical circuit forming layer at a predetermined position and cutting the optical circuit forming layer over a predetermined length to a predetermined depth, and then moving the rotary blade or cutting tool away from the cutting position. In this case, the inclined surface can be formed in a portion of the formed plural cores, in the predetermined number of the formed plural cores or all of the formed plural cores.
The cutting operation by the rotary blade or cutting tool may be carried out to such a depth as a portion of the thickness of the core formed in the optical circuit forming layer 1 remains. By leaving a portion of the thickness to remain in this way, a deflector portion for light splitting can be formed that divides the light propagating through the core into a portion that extracts the light from the deflector portion and a portion that passes the light through the core.
In a preferred form, the cutting operation can be carried out by bringing a rotary blade 241 into contact with the optical circuit forming layer 201 at a predetermined position and cutting the optical circuit forming layer, then cutting the same area again by using a second rotary blade 241 having smaller abrasive grains than those of the first rotary blade 241 . In this case, after cutting the inclined surface with the rotary blade of larger abrasive grains, the inclined surface can be finished with the second rotary blade of smaller abrasive grains. This enables it to form the smoother inclined surface of finer surface roughness, without causing strain or burrs by dragging of the resin at the cut-in point of the surface due to insufficient cutting force.
The deflector portion may be formed by providing the optical circuit forming layer with a reflector that has a reflecting surface inclined with respect to the propagating direction of light or optical axis in the core. In this case, the deflector portion can be formed easily by simply providing the reflector that has a reflecting surface in the optical circuit forming layer.
In other embodiment, the deflector portion may be formed by providing a periodical structure at least in the optical circuit forming layer or in the interface between the optical circuit forming layer and the adjacent layer. The periodical structure refers to any member of which structural feature is repeated in the direction of light propagation. For example, the periodical structure may be a member that can function as a grating. The deflector portion can be formed easily by providing the periodical structure.
The deflector portion may be formed before the step of forming the core of the optical waveguide. In this case, even when the optical circuit forming layer is made of a resin that cures when forming the core of the optical waveguide, the deflector portion can be easily formed before the resin cures to increase its rigidity.
In the case wherein two electrical circuits located at different positions in the direction of thickness in the optical circuit-electrical circuit mixedly mounting substrate are to be electrically connected by means of a via hole(s), the via hole(s) may be formed by laser etching while using a metal layer as the laser stopping layer, that metal layer is used as the electrical wiring of one of the electrical circuits. In this case, the electrical circuits can be electrically connected with each other using the via hole(s) with high reliability.
In other embodiment of the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate of the present invention, by using the material for the optical circuit-electrical circuit mixedly mounting substrate having the optical circuit forming layer made of a material of which refractive index increases when irradiated with the activating energy beam, intensity of the activating energy beam applied to the optical circuit forming layer is controlled in the step (1) of forming the core of the optical waveguide, so that the refractive index of only a portion in the direction of the thickness of the optical circuit forming layer irradiated with the activating energy beam is increased while the refractive index of the rest of the optical circuit forming layer adjacent thereto in the direction of said thickness remains the same, and thereby said portion is obtained as the core having an increased refractive index. In this case, a cladding layer can be formed in the rest of the optical circuit forming layer where the refractive index has not been increased, so that there is no need to provide a resin layer to form the cladding portion on this side, thereby simplifying the structure of the stacked layers and making it easier to manufacture the optical circuit-electrical circuit mixedly mounting substrate.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows an embodiment of the material for the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 1( a ) to FIG. 1( e ) are schematic sectional views thereof.
FIG. 2 shows a process of manufacturing the optical circuit-electrical circuit mixedly mounting substrate from the material for the optical circuit-electrical circuit mixedly mounting substrate shown in FIG. 1( a ), and FIG. 2( a ) to FIG. 2( e ) are schematic sectional views thereof.
FIG. 3 shows another embodiment of the material for the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 3( a ) to FIG. 3( e ) are schematic sectional views thereof.
FIG. 4 shows steps of manufacturing the optical circuit-electrical circuit mixedly mounting substrate from the material for the optical circuit-electrical circuit mixedly mounting substrate shown in FIG. 3( a ), and FIG. 4( a ) to FIG. 4( e ) are schematic sectional views thereof.
FIG. 5 shows other embodiment of the material for the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 5( a ) to FIG. 5( e ) are schematic sectional views thereof.
FIG. 6 shows the steps of manufacturing the optical circuit-electrical circuit mixedly mounting substrate from the material for the optical circuit-electrical circuit mixedly mounting substrate shown in FIG. 5( a ), and FIG. 6( a ) to FIG. 6( e ) are schematic sectional views thereof.
FIG. 7 shows other embodiment of the material for the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 7( a ) to FIG. 7( e ) are schematic sectional views thereof.
FIG. 8 shows the steps of manufacturing the optical circuit-electrical circuit mixedly mounting substrate from the material for the optical circuit-electrical circuit mixedly mounting substrate shown in FIG. 7( a ), and FIG. 8( a ) to FIG. 8( e ) are schematic sectional views thereof.
FIG. 9 shows other embodiment of the material for the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 9( a ) to FIG. 9( e ) are schematic sectional views thereof.
FIG. 10 shows the steps of manufacturing the optical circuit-electrical circuit mixedly mounting substrate from the material for the optical circuit-electrical circuit mixedly mounting substrate shown in FIG. 9( a ), and FIG. 10( a ) to FIG. 10( d ) are schematic sectional views thereof.
FIG. 11 shows other embodiment of the material for the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 11( a ) to FIG. 11( e ) are schematic sectional views thereof.
FIG. 12 shows the steps of manufacturing the optical circuit-electrical circuit mixedly mounting substrate from the material for the optical circuit-electrical circuit mixedly mounting substrate shown in FIG. 11( a ), and FIG. 12( a ) to FIG. 12( d ) are schematic sectional views thereof.
FIG. 13 shows other embodiment of the material for the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 13( a ) to FIG. 13( e ) are schematic sectional views thereof.
FIG. 14 shows the steps of manufacturing the optical circuit-electrical circuit mixedly mounting substrate from the material for the optical circuit-electrical circuit mixedly mounting substrate shown in FIG. 13( a ), and FIG. 14( a ) to FIG. 14( d ) are schematic sectional views thereof.
FIG. 15 shows other embodiment of the material for the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 15( a ) to FIG. 15( e ) are schematic sectional views thereof.
FIG. 16 shows the steps of manufacturing the optical circuit-electrical circuit mixedly mounting substrate from the material for the optical circuit-electrical circuit mixedly mounting substrate shown in FIG. 15( a ), and FIG. 16( a ) to FIG. 16( d ) are schematic sectional views thereof.
FIG. 17 shows one example of an embodiment of the process of the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 17( a ) to FIG. 17( h ) are schematic sectional views thereof.
FIG. 18 shows one example of an embodiment of forming a reflector in a deflector portion in the process of the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 18( a ) and FIG. 18( b ) are partially enlarged schematic sectional views thereof.
FIG. 19 shows one example of an embodiment of forming a deflector portion in the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 19( a ) and FIG. 19( b ) are partially enlarged schematic sectional views thereof.
FIG. 20 shows a schematic sectional view of one example of an embodiment of forming a deflecting portion in the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate.
FIG. 21 shows one example of forming a deflecting portion having a reflector, and FIG. 21( a ) and FIG. 21( b ) are partially enlarged schematic sectional views thereof.
FIG. 22 shows the steps of one example of an embodiment of the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 22( a ) to FIG. 22( h ) are schematic sectional views thereof.
FIG. 23 shows the steps of one example of the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 23( a ) to FIG. 23( h ) are schematic sectional views thereof.
FIG. 24 shows one example of an embodiment for forming a deflecting portion in the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 24( a ) and FIG. 24( b ) are schematic sectional views thereof.
FIG. 25 shows one example for manufacturing the optical circuit-electrical circuit mixedly mounting substrate according to the present invention wherein means for efficiently transmitting light to the deflector portion or from the deflector portion is formed, and FIG. 25( a ), FIG. 25( b ) and FIG. 25( c ) are schematic sectional views thereof.
FIG. 26 shows the steps of one example of an embodiment of the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 26( a ) to FIG. 26( i ) are schematic sectional views thereof.
FIG. 27 shows the steps of one example of an embodiment of the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 27( a ) to FIG. 27( i ) are schematic sectional views thereof.
FIG. 28 shows the steps of one example of an embodiment of the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 28( a ) to FIG. 28( j ) are schematic sectional views thereof.
FIG. 29 shows the steps of one example of an embodiment of the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, and FIG. 29( a ) to FIG. 29( j ) are schematic sectional views thereof.
FIG. 30 shows one example of an embodiment for manufacturing the optical circuit-electrical circuit mixedly mounting substrate according to the present invention wherein means for efficiently transmitting light to the deflector portion or from the deflector portion is formed, and FIG. 30( a ) and FIG. 30( b ) are schematic sectional views thereof.
FIG. 31 shows one example of an embodiment for manufacturing the optical circuit-electrical circuit mixedly mounting substrate according to the present invention wherein a lens for efficiently transmitting light to the deflector portion or from the deflector portion is located, and FIG. 31( a ), FIG. 31( b ) and FIG. 31( c ) are enlarged schematic sectional views thereof.
FIG. 32 shows the steps of one example of an embodiment of the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, wherein FIG. 32( a ) to FIG. 32( k ) are schematic sectional views thereof.
FIG. 33 shows the steps of one example of an embodiment of the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate according to the present invention, wherein FIG. 33( a ) to FIG. 33( i ) are schematic sectional views thereof.
DESCRIPTION OF REFERENCE NUMERALS
- 1 : Light permeable resin layer
- 2 : Optical circuit forming layer
- 3 , 4 , 5 , 6 : Optical circuit forming layer
- 7 : Second light permeable resin layer
- 8 : Optical circuit forming layer
- 9 : Second light permeable resin layer
- 10 : Optical circuit forming layer
- 11 : Light permeable resin layer
- 12 : Optical circuit forming layer
- 13 : Metal layer
- 14 : Adhesive layer
- 15 : Cover film
- 16 : Supporting member
- 201 : Optical circuit forming layer
- 202 : Metal layer
- 203 : Stacked structure
- 204 : Optical waveguide
- 204 a : Core
- 204 b : Cladding portion
- 205 : Deflector portion
- 206 : Electrical circuit
- 207 : Inclined surface
- 208 : Light reflector
- 209 : Reflecting surface
- 210 : Reflector
- 211 : Wiring board
- 212 : Electrical circuit
- 213 : Via hole
- 214 : Adhesive
- 215 : Cover film
- 216 : Light permeable resin
- 217 : Light permeable resin layer
- 240 : Cutting blade
- 241 : Rotary blade
- 244 : Polymer film
- 246 : Lens
- 247 : Light permeable resin
EMBODIMENTS FOR CARRYING OUT THE INVENTION
Embodiments of the present invention will be now described.
FIG. 1( a ) shows one example of an embodiment of the material for the optical circuit-electrical circuit mixedly mounting substrate of the present invention according to the seventh aspect, wherein an optical circuit forming layer 2 is stacked in direct contact with one side of a light permeable resin layer 1 , and a metal layer 13 is stacked on a side of the light permeable resin layer 1 opposite to the side where the optical circuit forming layer 2 is provided. The metal layer 13 is preferably a copper foil. While there is no limitation as to the thickness of the metal layer 13 , the thickness is usually in the range from 9 to 70 μm.
The light permeable resin layer 1 is made of a light permeable resin. The optical circuit forming layer 2 is made of a light permeable resin (or a photosensitive resin) of which solubility to solvent changes when irradiated with an activating energy beam. These resins may be selected from the resins previously mentioned. The resin used to form the optical circuit forming layer 2 is a resin that has a refractive index higher than that of the resin used to form the light permeable resin layer 1 or, a resin of which refractive index becomes higher than that of the resin used to form the light permeable resin layer 1 when irradiated with the activating energy beam.
An example of the method for manufacturing the optical circuit-electrical circuit mixedly mounting substrate will be described below. In the case wherein a metal foil is used as the metal layer 13 , one side thereof, preferably a mat surface thereof is coated with the resin used to form the light permeable resin layer 1 . The coating may be carried out by a comber coater, a curtain coater, a die coater, screen printing, offset printing or the like. Then the light permeable resin layer 1 is coated with the resin to form the optical circuit forming layer 2 thereon by similar coating process, and thereby to obtain the material for the optical circuit-electrical circuit mixedly mounting substrate as shown in FIG. 1( a ).
Then, the method to manufacture the optical circuit-electrical circuit mixedly mounting substrate by using the material for the optical circuit-electrical circuit mixedly mounting substrate obtained as described above will be described below. First, as shown in FIG. 2( a ), the optical circuit forming layer 2 is irradiated with an activating energy beam E on the side opposite to the metal layer 13 . The irradiation of the activating energy beam is carried out in accordance to a pattern of the core of the optical circuit. For example, masked exposure with ultraviolet ray, drawing (or lithographic) exposure with laser beam or the like may be employed for the irradiation with the activating energy beam.
Then, the optical circuit forming layer 2 is processed with a solvent to develop the irradiated pattern and partially remove the optical circuit forming layer 2 . In the case wherein the optical circuit forming layer 2 is made of a resin such as a photocurable resin of which solubility to solvent decreases in a portion thereof that is irradiated with the activating energy beam, the resin in portion other than said portion irradiated with the activating energy beam dissolves in the solvent and the resin remains in the portion that has been irradiated with the activating energy beam. In the case wherein the optical circuit forming layer 2 is made of a resin such as a photo-degrading resin of which solubility to solvent increases in a portion thereof that is irradiated with the activating energy beam, the resin in portion irradiated with the activating energy beam dissolves in the solvent and the resin remains in portions other than the portion that has been irradiated with the activating energy beam. The solvent is selected in accordance with the resin that constitutes the optical circuit forming layer. Such a selection is conventionally practiced in the field of manufacturing wiring boards.
After forming the optical circuit forming layer 2 shown in FIG. 2( b ) in the predetermined optical circuit pattern as described above, the side of the light permeable resin layer 1 on which the optical circuit forming layer 2 is provided is coated with the light permeable resin layer 20 , so as to cover the optical circuit pattern 2 with the light permeable resin layer 20 as shown in FIG. 2( c ). For the light permeable resin layer 20 , a light permeable resin that has a refractive index lower than that of the optical circuit forming layer 2 , and thus that of the optical circuit pattern functioning as the core is used and, for example, the same resin as that used for the light permeable resin layer 1 may be used.
Then, a printed wiring board 22 having an electric wiring 21 formed thereon is prepared in advance, and the light permeable resin layer 20 is bonded onto the surface of the printed wiring board 22 by using an adhesive 23 as shown in FIG. 2( d ). The metal layer 13 on the surface is then processed to form an electrical wiring 24 as shown in FIG. 2( e ), and the electrical wiring 21 and the electrical wiring 24 are electrically connected with each other by laser via processing or plating processing.
In FIG. 2( e ), since the refractive index of the optical circuit pattern formed from the optical circuit forming layer 2 is higher than the refractive indices of the light permeable resin layer 1 and the light permeable resin layer 20 that are in direct contact with the optical circuit forming layer 2 , an optical waveguide is formed from the core layer 26 made from the optical circuit forming layer 2 and a cladding layers 27 formed from the light permeable resin layer 1 and the light permeable resin layer 20 , so that the optical circuit is formed by the optical circuit forming layer 2 . Thus, the optical circuit formed by the optical circuit forming layer 2 , the electrical wiring 21 and the electrical wiring 24 are stacked one on another, which is used as optical circuit-electrical circuit mixedly mounting substrate. The light permeable resin layer 20 may be omitted when the adhesive 23 is permeable to light and has a refractive index lower than that of the optical circuit forming layer 2 .
It is not essential for the material of the present invention to stack the material for the optical circuit-electrical circuit mixedly mounting substrate having the core formed on the printed wiring board 22 as described above. Instead, the material for the optical circuit-electrical circuit mixedly mounting substrate includes, on only one side thereof, the electrical wiring 24 obtained by processing the metal layer 13 . Alternatively, by stacking a metal foil instead of the printed wiring board 22 , the material for the optical circuit-electrical circuit mixedly mounting substrates may be manufactured to include the electrical wirings 24 on both sides thereof.
FIG. 1( b ) shows another embodiment of the material for the optical circuit-electrical circuit mixedly mounting substrate according to the twelfth aspect, wherein an adhesive layer 14 that is flame-resistant is interposed between the metal layer 13 and the light permeable resin layer 1 . In the case wherein a metal foil is used as the metal layer 13 , the adhesive layer 14 can be formed by coating one side thereof or a mat surface side thereof if any with the adhesive by the coating method described above and, in the case wherein the adhesive contains a solvent, removing the solvent by drying and curing or semi-curing the adhesive if necessary. Thereafter, the light permeable resin layer 1 is coated on the adhesive layer 14 similarly and the optical circuit forming layer 2 is formed thereon by coating, thereby to obtain the material for the optical circuit-electrical circuit mixedly mounting substrate.
Interposing the adhesive layer 14 between the metal layer 13 and the resin layer makes it possible to increase the strength of bonding the metal layer 13 onto the resin layer by means of the adhesive layer 14 . Also, because the adhesive layer 14 contains a flame retardant, it is made possible to provide the flame resistance.
FIG. 1( c ) shows one example of an embodiment of the material for the optical circuit-electrical circuit mixedly mounting substrate according to the fourteenth aspect, wherein the optical circuit forming layer 2 is covered by a transparent cover film 15 on the surface which is opposite to the metal layer 13 . The cover film 15 may be may be either laminated on the resin layers 1 and 2 formed on the metal layer 13 , or formed by coating the cover film 15 with the resin layer 2 and laminating the film 15 coated with the resin layer 2 onto the metal layer 13 on which the light permeable resin layer 1 has been formed.
Laminating the cover film 15 on the resin layer prevents the resin layer from being exposed, and therefore improves the workability of handling the material for the optical circuit-electrical circuit mixedly mounting substrate. Exposu