DETAILED DESCRIPTION OF THE INVENTION

[0060] In one embodiment of the present invention, a conductive portion having a fine pattern is formed in an insulating body by performing at least steps (1) to (5) given below. The following description covers the case of using a photosensitive composition containing a compound capable of forming ion-exchange groups upon irradiation with an energy beam.

[0061] Step (1): In the first step, a photosensitive layer containing a compound capable of forming ion-exchange groups upon irradiation with an energy beam is formed on the surface of an insulating substrate. The photosensitive layer formed in this step is a photosensitive composition layer. The shape of the substrate is not particularly limited. It is possible to use substrates of various shapes such as plate-like, linear, cylindrical and spherical substrates. In the case of using a porous substrate, it is possible to form a conductive pattern within the porous body, too.

[0062] Step (2): In the next step, the photosensitive composition layer formed on the substrate is selectively exposed to light (an energy beam such as light) in a pattern so as to form ion-exchange groups in the exposed portion of the photosensitive composition layer. Where the substrate is porous, it is also possible for the inner region of the substrate to be exposed to light. The selective light exposure in a pattern can be performed by using a light exposure mask or by scanning a laser beam. It is possible to modulate the light emitted from the light source by using a mirror array formed by arranging a large number of fine mirrors. In the case of using a porous substrate, it is also possible to form a conductive pattern within the porous body because the exposing light permeates into the inner region of the porous body.

[0063] Step (3): Then, the crosslinkable compound contained in the photosensitive composition layer is crosslinked. It is possible to carry out the crosslinking before or simultaneously with the light exposure step. By the crosslinking of the crosslinkable compound, it is possible to improve the resistance of the photosensitive layer to the plating solution.

[0064] Step (4): Metal ions, metal compound, metal colloid is allowed to be adsorbed the ion-exchange groups formed in the light-exposed portion. The metal ions or metal compounds form a salt or a covalent bond together with the ion-exchange group so as to be adsorbed. The metal colloid is generally charged and, thus, are electrostatically adsorbed on the ionized ion-exchange group. These metal ions, metal compound and metal colloid perform the function of a catalytic nucleus of the electroless plating. Where the metal ions and metal compound are adsorbed, it is possible to apply a reducing treatment as required so as to convert the metal ions and metal compound into metal, thereby improving the catalytic function of the electroless plating.

[0065] Step (5): An electroless plating is applied with the metal ions, the metal compound or the metal colloid adsorbed on the ion-exchange group in the exposed portion used as a catalytic nucleus.

[0066] Incidentally, in the case of using a photosensitive composition containing a compound causing an ion-exchange group to disappear upon exposure to light, the ion-exchange group in the exposed portion is caused to disappear in the selective light exposure in a pattern in step (2) described above, with the result that the ion-exchange groups are allowed to remain selectively in the unexposed portion, thereby forming a negative pattern.

[0067] It is also possible to allow the ion-exchange groups formed in the exposed portion by the selective light exposure in a pattern to react selectively with, for example, a fluorine compound so as to eliminate the ion exchange capability. Then, ion-exchange groups are generated in the unexposed portion in the selective light exposure step in a pattern by applying the light exposure to the entire surface or by applying a heat treatment. It is possible to allow metal ions, metal compound or metal colloid to be adsorbed on the ion-exchange groups thus formed. In the case of employing this technology, however, it is necessary to carry out the light exposure operation twice or to apply a heat treatment so as to give rise to the defects that the process step is rendered complex and that the dimensional stability is lowered in the manufactured composite member. What should also be noted is that the surface after the reaction with the fluorine compound is rendered water repellent. Since the plating solution is repelled by the water repellent surface, defective plating tends to be brought about. Particularly, where the substrate is porous, the plating solution is unlikely to permeate inside the porous substrate.

[0068] Steps (1) to (5) of the method of manufacturing a composite member according to one embodiment of the present invention do not require troublesome steps such as a resist coating, an etching and the peeling of the resist so as to simplify the manufacturing process, compared with the conventional method of manufacturing a wiring board in which a through-hole is formed by photolithography or a mechanical means. Also, in the case of using a porous material as the insulating substrate, it is also possible to form a conductive pattern within the substrate so as to make it possible to manufacture easily a multi-layered wiring board having micro vias.

[0069] It should also be noted that, in the manufacturing method according to one embodiment of the present invention, steps (1) to (5) described above can be continuously carried out on the roll-to-roll basis so as to increase the throughput in the manufacturing step.

[0070] It is possible to use any kind of an insulating material for forming the insulating body in which are formed conductive portions such as wirings and vias. To be more specific, the insulating material includes polymers and ceramic materials.

[0071] The polymers used as the insulating material include, for example, resins widely used for forming the insulating body of a printed circuit wiring board such as an epoxy resin, a bismaleimide-triazine resin, a PEEK resin, and a butadiene resin. It is also possible to use polyolefins such as polyethylene and polypropylene; polydienes such as polybutadiene, polyisoprene, and polyvinyl ethylene; acrylic resins such as polymethyl acrylate and polymethyl methacrylate; polystyrene derivatives; polyacrylonitrile derivatives such as polyacrylonitrile and polymethacrylonitrile; polyacetals such as polyoxymethylene; polyesters such as polyethylene terephthalate, polybutylene terephthalate and aromatic polyesters; polyarylates; polyamides such as aromatic polyamides including para- and meta-aramid resins and nylon; polyimides; aromatic polyethers such as poly-para-phenylene ether; polyether sulfones; polysulfones; polysulfides; fluorine-containing polymers such as polytetrafluoro ethylene; polybenzoxazoles; polybenzothiazoles; polybenzimidazoles; polyphenylenes such as poly-para-phenylene; poly-para-phenylene benzo bis oxazole derivatives; poly-para-phenylene vinylene derivatives; polysiloxane derivatives; novolak resins; melamine resins; urethane resins; and polycarbodiimide resins.

[0072] On the other hand, the ceramic materials include, for example, metal oxides such as silica, alumina, titania, and potassium titanate as well as silicon carbide, silicon nitride and aluminum nitride.

[0073] Particularly, in the case of forming a conductive portion extending three-dimensionally, i.e., in the case of forming a conductive portion extending not only in the planar direction but also in the thickness direction, it is possible to form easily a conductive portion of a high accuracy by using a porous body formed of an insulating material. The porous body has numerous three-dimensional continuous micropores. Conductive material such as copper can be introduced within the porous body through the continuous micropores. The portion impregnated with copper are conductive and the portion impregnated with resin are insulative. The conductive portion act as a via or a wiring, and the insulative domains act as an insulative layers. The conductive portion formed through a porous sheet become vias, and the conductive portion formed along a porous sheet become wiring. Such a three-dimensional conductive portion can be used as three-dimensional wiring, as multi-layered wiring, or as a via for the interlayer connection in multi-layered wiring.

[0074] The photosensitive layer formed in the method of manufacturing a composite member according to one embodiment of the present invention contains a photosensitive group or a photosensitive compound capable of forming an ion-exchange group or of eliminating the ion-exchange group upon irradiation with an energy beam. The photosensitive compound can be used in the form of a photosensitive composition containing a crosslinkable compound. Alternatively, the photosensitive compound can be converted into a polymer, and a crosslinkable group can be introduced into the polymer chain. Such a polymer can be mixed with other components so as to form a photosensitive composition. In the following description, a composition containing such a polymer is called a photosensitive material.

[0075] The photosensitive group or the photosensitive compound capable of forming an ion-exchange group or eliminating the ion-exchange group upon irradiation with an energy beam is capable of carrying out a chemical reaction by itself by absorbing the irradiated energy beam so as to form a group or a compound generating an ion-exchange group. Alternatively, it is possible for the particular photosensitive group or the photosensitive compound noted above to be capable of carrying out multi-stage reactions, which is initiated by a chemical reaction caused by the energy beam exposure, so as to generate an ion exchange group. Such a group or a compound carries out first a chemical reaction caused by the energy beam irradiation so as to generate a precursor of the ion-exchange group. Then, the precursor thus generated carries out a chemical reaction with the ambient substance so as to form an ion-exchange group. Further, it is possible for the precursor to act on, for example, an acid generated from the photo acid generating agent by the irradiation with an energy beam so as to form an ion-exchange group.

[0076] The photosensitive group or the photosensitive compound absorbing an energy beam so as to form an ion-exchange group by itself includes, for example, o-nitrobenzyl ester derivative of a carboxylic acid, a sulfonic acid, or silanol; p-nitrobenzyl ester sulfonate derivative, naphtyl or phthalimide trifluoro sulfonate derivative. It is also possible to use peroxide esters such as a peroxide of tert-butyl ester of a carboxylic acid as such a photosensitive group or a photosensitive compound. Where a peroxide ester is irradiated with an energy beam, formed is a carboxyl group as the ion-exchange group. Upon irradiation with an energy beam, the peroxide esters form radicals together with ion-exchange groups. As described herein later, the radical thus generated also performs the function of crosslinking the crosslinkable group and, thus, is highly useful.

[0077] The materials generating an ion-exchange group by multi-stage reactions initiated by a chemical reaction caused by the energy beam irradiation include, for example, quinone diazides. Upon irradiation with an energy beam, quinone diazides form a ketene intermediate material. Then, the ketene intermediate material thus formed subsequently performs a reaction with water so as to be converted into indene carboxylic acids. The carboxyl group is formed through these steps. The quinone diazides include o-quinone diazide derivatives such as benzoquinone diazide, naphthoquinone diazide and anthraquinone diazide.

[0078] The material acting on, for example, an acid generated from a photo acid generating agent upon irradiation with an energy beam so as to form an ion-exchange group includes, for example, a compound having an atomic group formed by introducing a protective group into an ion-exchange group such as a carboxyl group, a phenolic hydroxyl group or a silanol group. In the case of using the particular compound, a photo acid generating agent generating an acid upon irradiation with an energy beam is added to the compound. An acid is generated from the photo acid generating agent by the irradiation with an energy beam, the protective group is decomposed by the acid thus generated so as to form an ion-exchange group. The protective group of the carboxyl group includes, for example, tert-butyl group, tert-butoxy carbonyl group, and acetal groups such as tetrahydropyranyl group. Also, the protective group of phenolic hydroxyl group and silanol group includes, for example, tert-butoxy carbonyl group and is used as tert-butoxy carbonyloxy group.

[0079] The photo acid generating agent adapted for de-protection of the protective group includes, for example, salts such as onium salt, diazonium salt, phosphonium salt, and iodonium salt having CF ₃ SO ₃ ⁻ , p—CH ₃ PhSO ₃ ⁻ , p—NO ₂ PhSO ₃ ⁻ , etc., as a paired anion, triazines, organic halogen compounds, 2-nitrobenzyl sulfonic acid esters, imino sulfonates, N-sulfonyloxy imides, aromatic sulfones, and quinone diazide sulfonic acid esters.

[0080] To be more specific, the photo acid generating agent includes, for example, triphenyl sulfonium triflate, diphenyl iodonium triflate, 2,3,4,4-tetrahydroxy benzophenone-4-naphthoquinone diazide sulfonate, 4-N-phenyl amino-2-methoxy phenyl diazonium sulfate, diphenyl sulfonyl methane, diphenyl sulfonyl diazo methane, diphenyl disulfone, □-methyl benzoin tosylate, pyrogallol trimesylate, benzoin tosylate, naphthal imidyl trifluoro methane sulfonate, 2-[2-(5-methylfulan-2-yl)ethenyl]-4,6-bis(trichloromethyl)-s -triazine, 2-[2-(fulan-2-yl)ethenyl]-4,6-bis(trichloromethyl)-s-triazin e, 2-[2-(4-diethylamino-2-methylphenyl)ethenyl]-4,6-bis(trichlo romethyl)-s-triazine, 2-[2-(4-diethyl amino ethyl)amino]-4,6-bis(trichloromethyl)-s-triazine.dimethyl sulfate, 2-[2-(3,4-dimethoxy phenyl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-(4-dimethoxy phenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-methyl-4,6-bis(trichloromethyl)-s-triazine and 2,4,6-tris(trichloromethyl)-s-triazine.

[0081] Particularly, it is desirable to use photo acid generating agents generating both an acid and a radical such as an iodonium salt and triazines. In the case of using the photo acid generating agent consisting of the particular compounds together with a crosslinkable compound or a crosslinkable group performing the crosslinking by the radical reaction, it is possible to perform simultaneously the generation of the ion-exchange group by an acid and the crosslinking by the radical so as to improve the sensitivity with a high efficiency.

[0082] Where a complex with an acetyl acetonate derivative of aluminum or zirconium is added to the system of generating a silanol group or a phenolic hydroxyl group, the generated silanol group or the phenolic hydroxyl group acts on the complex so as to generate a relatively strong acid. The acid thus generated further generates a silanol group or a phenolic hydroxyl group. Alternatively, the acid crosslinks the crosslinkable group such as an epoxy group.

[0083] The photosensitive group or the photosensitive compound capable of eliminating the ion-exchange group upon irradiation with an energy beam represents a group or a compound having an ion-exchange group before irradiation with the energy beam and having the ion-exchange group released therefrom or converted into a hydrophobic group upon irradiation with the energy beam. To be more specific, the particular photosensitive group or photosensitive compound noted above includes, for example, a group or a compound having a carboxyl group subjected to a decarboxylation reaction so as to be decomposed. It is desirable for the group or the compound having a carboxyl group to be a group or a compound in which the decarboxylation reaction tends to be promoted by a basic compound. The particular group or compound includes, for example, a group or a compound having an electron attractive group or an unsaturated bond in the □- or □-position of the carboxyl group. It is desirable for the electron attractive group to be a carboxyl group, a cyano group, a nitro group, aryl group, a carbonyl group or a halogen atom.

[0084] The compound having a carboxyl group includes, for example, □-cyano carboxylic acid derivative, □-nitro carboxylic acid derivative, □-phenyl carboxylic acid derivative, □,□-olefin carboxylic acid derivative, and an indene carboxylic acid derivative. In the case of using a photo base generating agent as a basic compound, a base is generated upon irradiation with an energy beam, and the carboxyl group is decarboxylated by the function of the generated base so as to be eliminated.

[0085] The photo base generating agent includes, for example, cobalt amine complex, ketone oxime esters, carbamates such as o-nitrobenzyl carbamates, and formamides. To be more specific, it is possible to use carbamates such as NBC-101 (CAS. No. [119137-03-0]) manufactured by Midori Kagaku K.K. It is also possible to use triaryl sulfonium salts such as TPS-OH (CAS. No. [58621-56-0] manufactured by Midori Kagaku K.K.

[0086] It is possible to use a photo acid generating agent and a basic compound in combination in place of the photo base generating compound. In this case, an acid is generated from the photo acid generating agent in the portion irradiated with an energy beam so as to neutralize the basic compound. On the other hand, in the nonirradiated portion, the basic compound acts on the compound having a carboxyl group so as to promote the decarboxylation reaction and, thus, to eliminate the carboxyl group. As a result, it is possible to arrange selectively the carboxyl groups in the irradiated portion alone.

[0087] It is possible to add optionally the basic compound as far as the basic compound is neutralized by the acid released from the photo acid generating agent and performs the function of a catalyst for the decarboxylation reaction of the compound having a carboxyl group. The basic compound may be either an organic compound or an inorganic compound. However, it is desirable for the basic compound to be a nitrogen-containing compound. To be more specific, the basic compound includes, for example, ammonia, primary amines, secondary amines and tertiary amines. It is desirable for the photo base generating agent and the basic compound to be contained in the photosensitive composition in an amount of 0.1 to 30% by weight, preferably 0.5 to 15% by weight. Where the content of the photo base generating agent or the basic compound is lower than 0.1% by weight, the decarboxylation reaction fails to proceed sufficiently. On the other hand, if the content noted above exceeds 30% by weight, the deterioration of the compound having a carboxylic group remaining in the unexposed portion tends to be promoted.

[0088] Where a photo acid generating agent and a basic compound are used in combination, the amount of the acid that can be generated from the photo acid generating agent should naturally be larger than the amount of base of the basic compound. To be more specific, the amount of the acid that can be generated from the photo acid generating agent should be not smaller than 1 equivalent, preferably not smaller than 1.2 equivalents. Incidentally, the equivalent denotes the amount represented by the formula:

E= ( U×V×W )/( X×Y )

[0089] where,

[0090] E denotes the equivalent;

[0091] U denotes the number of moles of the photo acid generating agent;

[0092] V denotes the number of acid molecules generated from one mole of the photo acid generating agent;

[0093] W denotes the valency of the generated acid;

[0094] X denotes the number of moles of the basic compound; and

[0095] Y denotes the valency of the basic compound.

[0096] It should be noted that the photosensitive layer is exposed to an alkaline or acidic aqueous solution in the subsequent step of adsorbing the metal ions, the metal compound, or the metal colloid and in the electroless plating step. The photosensitive layer ionized by the ion exchange reaction tends to be dissolved in the aqueous solution and, thus, tends to be peeled from the insulating body forming the substrate. Such being the situation, it is desirable for the group generating or eliminating an ion-exchange group to be supported by or coupled with, for example, a high molecular weight compound such as a polymer in order to prevent the photosensitive layer from being peeled off the substrate. It is most desirable for the group generating an ion-exchange group to be chemically coupled with a high molecular weight compound by a covalent bond.

[0097] The polymer or the high molecular weight compound includes, for example, phenolic resins such as phenol novolak resin, xylenol novolak resin, vinyl phenol resin, cresol novolak resin as well as polyimide resin, polyester resin, polyolefin resin, polyacrylic acid ester derivatives and polysiloxane derivatives.

[0098] Where the amount of the ion-exchange group introduced into the polymer is excessively small, it is difficult to adsorb sufficiently the metal ions, the metal compound, or the metal colloid. On the other hand, where the ion-exchange group is introduced in an excessively large amount, the ion-exchange group tends to be dissolved in the plating solution and tends to be swollen so as to render the manufactured composite member excessively hygroscopic. It follows that an inconvenience such as a defective insulation tends to take place. Under the circumstances, it is desirable for the group generating or eliminating the ion-exchange group to be introduced into the polymer in an amount falling within a range of between 5% and 300%, more preferably between 30% and 70%. Incidentally, the rate of introduction is represented by the formula:

I=M/N× 100

[0099] where

[0100] I represents the rate of introduction (%);

[0101] M represents the number of groups generating or eliminating the ion-exchange group; and

[0102] N represents the number of monomer units of the polymer.

[0103] It is desirable for the ion-exchange group to be a cation-exchangeable group because the ion exchange with the metal ions can be performed easily in the case of the cation-exchangeable group. It is desirable for the cation-exchangeable group to be, for example, a carboxyl group, its salt of —COOX group, a sulfoxyl group, its salt of —SO ₃ X group, a phosphoric acid radical, its salt of —PO ₃ X ₂ radical, a silanol group, its salt of —SIOX group, a phenolic hydroxyl group, its salt of —φ—OX group, where X is selected from the group consisting of a hydrogen atom, an alkali metal, an alkaline earth metal, a typical metal belonging to Groups I or II of the Periodic Table, and an ammonium group, and φ is a divalent aromatic ring.

[0104] Among the cation-exchangeable groups, it is desirable to use a cation-exchangeable group exhibiting not larger than 7.2 of the pKa value obtained from the ion dissociation constant within water. If the pKa value exceeds 7.2, the adsorption amount per unit area is small in the subsequent step (step 4) of adsorbing the metal ions, the metal compound, or the metal colloid. As a result, it is possible for the electroless plating to fail to be performed sufficiently. It is most desirable to use as the cation-exchangeable group the —COOX group that permits obtaining a sufficient adsorption amount. Incidentally, the —SO ₃ X group also permits obtaining a sufficient adsorption amount. However, it is possible for a strong acid to be generated after manufacture of the composite member so as to corrode the conductive pattern.

[0105] In the photosensitive composition according to one embodiment of the present invention, it is desirable for the content of the photosensitive compound to fall within a range of between 5% by weight and 95% by weight, more desirably between 20% by weight and 80% by weight. Where the content of the photosensitive compound is excessively low, the amount of the ion-exchange group is not sufficiently large so as to make it difficult to achieve satisfactory plating. On the other hand, if the content of the photosensitive compound is excessively large, the photosensitive compound is dissolved in the plating solution or is swollen. In addition, the manufactured composite member is rendered hygroscopic so as to bring about an insulation breakdown.

[0106] In addition to the photosensitive compound, the photosensitive composition according to one embodiment of the present invention also contains a crosslinkable compound or a crosslinkable group as an indispensable component.

[0107] Used in one embodiment of the present invention is a crosslinkable compound or a crosslinkable group, which can be crosslinked three-dimensionally by the irradiation with an energy beam or by the heating so as to be polymerized. If the crosslinkable compound or the crosslinkable group is crosslinked and polymerized, the photosensitive composition layer is enabled to exhibit an improved resistance to, for example, the plating solution. As a result, it is possible to increase the content of the ion-exchange group in the photosensitive composition layer, thereby achieving satisfactory plating. It is possible for the crosslinkable compound or the crosslinkable group to be self-polymerized and crosslinked or to be coupled with another substance contained in the photosensitive composition layer so as to be crosslinked.

[0108] The crosslinkable groups capable of self-polymerization include, for example, a vinyl group, an acryloyl group, a methacryloyl group, an epoxy group such as a glycidyl group, a vinyl ether group, chloromethyl phenyl group, an alkoxy silyl group, a benzocyclobutene group, a maleimidyl group and derivative groups thereof. On the other hand, the crosslinkable compound includes a compound having the crosslinkable groups noted above introduced to the backbone chain, the side chain or the terminal of a polymer. The compound having the crosslinkable group introduced therein need not be a polymer. However, a polymer having a high molecular weight even before the crosslinking is allowed to have a still higher molecular weight by the crosslinking, which is effective for improving the resistance to the solvent.

[0109] The molecular weight of the polymer is not particularly limited. However, it is desirable for the polymer to have a weight average molecular weight of 500 to 5,000,000, more desirably to have a weight average molecular weight of 1,500 to 50,000. Where the molecular weight of the polymer is excessively low, the polymer is low in its film forming capability, and the resistance to the solvent such as the resistance to the plating solution tends to be lowered. On the other hand, if the molecular weight of the polymer is excessively high, the dissolving capability of the polymer in a solvent for the coating is lowered so as to render the coating properties poor.

[0110] The crosslinkable group in the case where the crosslinkable group is coupled with another substance contained in the photosensitive composition layer so as to achieve the crosslinking includes, for example, a hydroxyl group and an amino group. On the other hand, the crosslinkable compound having the particular crosslinkable group includes a compound having the particular crosslinkable group introduced into the backbone chain, the side chain or the terminal of a polymer. In the case of using the particular crosslinkable compound, used is a crosslinking assistant having a plurality of atomic groups capable of coupling with the hydroxyl group or the amino group so as to permit the atomic groups to be coupled with the hydroxyl group or the amino group so as to form a crosslinked coupling. The crosslinking assistant includes, for example, alkoxy silanes, aluminum alkoxides, carboxylic anhydrides, bismaleimide derivatives, isocyanate compounds, polyhydric methylol compounds and epoxy compounds.

[0111] It is possible to use as the crosslinkable group the atomic groups capable of dimerization upon irradiation with an energy beam. The particular atomic groups are advantageous in that the irradiated portion alone can be selectively crosslinked. However, the atomic groups noted above absorb partly the energy beam. The particular atomic groups include, for example, a cinnamoyl group, a cinnamilidene group, a chalcon residue, an isocumarine residue, 2.5-dimethoxy stilben residue, a styryl pyrimidium residue, a thymine residue, an □-phenyl maleimidyl group, an anthracene residue and a 2-pyron residue.

[0112] The polymer having the crosslinkable group introduced therein includes, for example, phenolic resins such as phenol novolak resin, xylenol novolak resin, vinyl phenol resin, cresol novolak resin, as well as polyamide derivatives, polyimide derivatives, polyester derivatives, polyether derivatives, polyacrylic acid ester derivatives, and polysiloxane derivatives. Where the amount of the crosslinkable groups introduced into the polymer is excessively small, the crosslinking does not proceed sufficiently, with the result that the polymer tends to be dissolved in the plating solution and tends to be swollen. On the other hand, where the crosslinkable groups are excessively introduced into the polymer, the photosensitive composition layer tends to be cured and shrunk in the crosslinking step, with the result that the substrate tends to be deformed or the photosensitive composition layer tends to be peeled from the substrate. It is desirable for the amount of the crosslinkable group introduced into the polymer to fall within a range of between 1% by weight and 300% by weight, more desirably, between 20% by weight and 200% by weight. Incidentally, the rate of introduction of the crosslinkable group is denoted by:

R=O/P× 100

[0113] where

[0114] R represents the rate of introduction of the crosslinkable group into the polymer;

[0115] O represents the number of crosslinkable groups; and

[0116] P represents the number of monomer units of the polymer.

[0117] It is possible to use as the crosslinkable compound or the crosslinkable group a material that reacts with the ion-exchange group so as to achieve coupling between the ion-exchange groups. For example, in a crosslinking agent having a plurality of hydroxyl groups, different carboxyl groups can be bonded to each other by an ester bond so as to achieve the crosslinking. However, such a crosslinkable compound decreases the amount of the ion-exchange groups generated by the light exposure in the preceding step, resulting in failure to achieve sufficient plating. In order to avoid such an inconvenience, it is desirable to use a material that can be crosslinked without utilizing an intervening ion-exchange group.

[0118] The crosslinkable compounds other than polymers are compounds having the crosslinkable groups described above. It is desirable for the crosslinkable compound other than the polymer to have a plurality of crosslinkable groups. To be more specific, the crosslinkable compounds other than polymers, which can be used in the present invention, include, for example:

[0119] (1) A compound having, for example, an acryloyl group, a methacryloyl group, a vinyl group or an allyl group introduced into a polyhydric alcohol, as shown in chemical formula (1) given below: 1

[0120] (2) Epoxy acrylates as shown in chemical formula (2) given below: 2

[0121] (3) Triazine derivatives introduced vinyl group etc. as shown in chemical formula (3) given below: 3

[0122] It is possible for the crosslinkable group to be a siloxane cluster derivative group such as POSS (Polyhedral Oligomeric Silsesquioxane: polysiloxane T ₈ steric body). Desirable examples of the polymer having the crosslinkable group introduced therein are those obtained by polymerizing monomers such as methacrylate T ₈ steric body shown in chemical formula (4) given below and styryl T ₈ steric body shown in chemical formula (5) given below: 4

[0123] methacrylate T ₈ steric body 5

[0124] styryl T ₈ steric body

[0125] where R represents H, a substituted or unsubstituted alkyl group, aryl group, or aralkyl group, e.g., methyl group, ethyl group, butyl group, isopropyl group, cyclopentyl group, cyclohexyl group or phenyl group.

[0126] Further, it is possible to use as the crosslinkable compound a polymer having an unsaturated bond such as a carbon-to-carbon double bond or a carbon-to-carbon triple bond introduced into the backbone chain of the polymer. Examples of a polymer having an unsaturated bond introduced therein include a polymer obtained by polymerizing diene monomers such as butadiene and cyclohexadiene and a monomer such as a norbornene derivative. In view of the resistance to heat, it is desirable to use a polymer obtained by polymerizing a cyclohexadiene derivative or a norbornene derivative. The specific cyclohexadiene derivatives include, for example, cyclohexadiene and an esterified material of 5,6-dihydroxy-2-cyclohexene-1,4-ylene such as cis-5,6-bis(pivaroyloxy)-2-cyclohexene-1,4-ylene. The unsaturated bond introduced into the backbone chain of the polymer is inferior to the crosslinkable group described above in terms of the reactivity. However, the polymer having the unsaturated bond introduced into the backbone chain can be manufactured easily. Also, since the polymer backbone chain is crosslinked directly, the polymer after the crosslinking treatment is excellent in its resistance to heat and its mechanical properties. It is possible to introduce such an unsaturated bond into the backbone chain of the polymer having a photosensitive group introduced therein. For the crosslinking of the carbon-to-carbon double bonds and the carbon-to-carbon triple bonds, it is desirable to add a radical generating agent. A polyfunctional radical generating agent having a plurality of radical generating groups in a single molecule exhibits a high crosslinking effect and, thus, is excellent. The polyfunctional radical generating agents include, for example, 2,2-bis(4,4-di-tert-butyl peroxy cyclohexyl)propane, and 3,3′,4,4′-tetra(t-butyl peroxy carbonyl)benzophenone.

[0127] It is most desirable for the crosslinking reaction to proceed on the basis of the radical reaction. For example, in the nucleophilic substitution reaction and the electrophilic substitution reaction such as a cation polymerization and anion polymerization, the reactant or the reaction intermediate product exhibit in many cases an ion exchange capability. It follows that it is possible for the adsorption of the metal ions, the metal compound, or the metal colloid to take place; unexpected positions.

[0128] In the radical reaction, however, it is possible for the crosslinking reaction to proceed in spite of nonuse of such an ion-exchangeable reactant or intermediate product. Also, since the reaction proceeds promptly even under room temperature, the heat treatment is unnecessary in general. It follows that it is possible to prevent the dimensional stability from being lowered and to prevent the thermal deterioration accompanying the heat treatment of the insulating body forming the substrate. It should also be noted that the bond of the crosslinked portion formed by the nucleophilic reaction or the electrophilic reaction tends to be decomposed by a strong acid or alkali. In general, the plating solution is a strong alkali in many cases and, thus, the crosslinked portion tends to be dissolved in the plating solution. On the other hand, the bond formed by the radical reaction is unlikely to be affected by a strong acid or a strong alkali. It follows that the crosslinking performed by the radical reaction is highly effective as a crosslinking means. For example, the crosslinking performed by the radical reaction permits preventing the thermal deterioration of the substrate, improves the selectivity in the adsorption step, and increases the resistance to the plating solution.

[0129] It is desirable for the content of the crosslinkable compound in the photosensitive composition to fall within a range of between 1% by weight and 50% by weight, more desirably between 10% by weight and 30% by weight. If the content of the crosslinkable compound is excessively low, it is impossible to achieve sufficient crosslinking, resulting in failure to ensure sufficiently the resistance to the solvent such as the resistance to the plating solution. On the other hand, if the content of the crosslinkable compound is excessively high, the photosensitive composition tends to be cured and shrunk so as to deform the substrate.

[0130] According to one embodiment of the present invention, it is possible for the photosensitive group and the crosslinkable group to be present independently in different compounds. However, it is desirable for a polymer to have both the photosensitive group and the crosslinkable group. Where a photosensitive compound having a photosensitive group is mixed with a crosslinkable compound having a crosslinkable group, it is possible for the photosensitive compound to fail are to be fixed sufficiently even if molecules of the crosslinkable compound are polymerized. On the other hand, when it comes to a polymer having both a photosensitive group and a crosslinkable group, the crosslinking reaction of the crosslinkable group can be effectively utilized for the fixation of all the photosensitive groups, leading to excellent efficiency.

[0131] When it comes to a polymer having both a photosensitive group and a crosslinkable group, it is desirable for the crosslinkable group to be capable of carrying out the radical polymerization by the reasons described previously. The crosslinkable group capable of the radical polymerization includes, for example, a vinyl group, an acryloyl group, a maleimidyl group and derivative groups thereof. These crosslinkable groups can be synthesized easily and exhibit a high efficiency of the crosslinking reaction. To be more specific, the crosslinkable group capable of the radical polymerization includes, for example, a vinyl group, an allyl group, a vinyl dimethyl silyl group, an acryloyl group, a methacryloyl group and a maleimidyl group. It is required for the polymer chain having a photosensitive group and a crosslinkable group introduced therein simultaneously to be good in coating properties of a solution, to be excellent in resistance to acid and alkali, to be high in bonding strength to the substrate, and to be excellent in resistance to heat. The amount of the adsorbed plating catalyst can be increased using the crosslinkable photosensitive polymer because the catalyst solution can diffuse across the photosensitive layer. Such being the situation, the desirable polymer chains include, for example, a novolak resin and its derivative, a polyacrylic acid ester and its derivative, a polystyrene derivative, a copolymer between a styrene derivative and a maleimide derivative, polynorbornene and its derivative, polycyclohexene and its derivative, polycyclohexane and its derivative, polyphenylene and its derivative, silicone resin, polyamides, polyimides and polyacrylates.

[0132] Particularly, it is desirable to use novolak resins such as phenol novolak and cresol novolak, a silicone resin, and copolymers synthesized by using as the raw materials a monomer group A into which a photosensitive group and a crosslinkable group can be introduced easily and a monomer group B for improving the solubility of the polymer chain and the resistance to heat. The monomer group A is a raw material before introduction of the photosensitive group and the crosslinkable group. It is possible to introduce the photosensitive group and the crosslinkable group into the monomer group A by a known technology. It is possible to synthesize the copolymer by using the monomers selected from the monomer group A. However, it is possible to improve the characteristics of the copolymer by suitably adding the monomer of the monomer group B.

[0133] The monomer group A includes, for example, 4-hydroxy styrene and maleic anhydride. On the other hand, the monomer group B includes, for example, a silylated styrene derivative such as p-pentamethyl disilyl styrene, a maleimide derivative such as phenyl maleimide, and norbornene.

[0134] It is desirable for the amount of the photosensitive group introduced into the polymer to fall within a range of between 5% and 300%, more desirably between 30% and 70%. On the other hand, it is desirable for the amount of the crosslinkable group introduced into the polymer to fall within a range of between 1% and 300%, more desirably between 20% and 200%. Incidentally, the rate of introduction is determined by the formula given below:

K=J/L

[0135] where

[0136] K represents the rate of introduction;

[0137] J represents the number of the photosensitive group or the crosslinkable group; and

[0138] L represents the number of monomer units of the polymer.

[0139] Where the amount of the photosensitive group introduced into the polymer is excessively small, it is difficult to allow the metal ions, the metal compound, or the metal colloid to be adsorbed sufficiently. On the other hand, where the amount noted above is excessively large, the photosensitive composition layer tends to be dissolved in the plating solution and tends to be swollen. In addition, the manufactured composite member tends to absorb moisture easily so as to bring about an inconvenience such as defective insulation. Where the amount of the crosslinkable group introduced into the polymer is excessively small, it is difficult to achieve the crosslinking sufficiently, with the result that the photosensitive composition layer tends to be dissolved easily in the plating solution and tends to be swollen. On the other hand, where the crosslinkable group is introduced excessively into the polymer, the photosensitive layer is cured and shrunk in the crosslinking step, with the result that the substrate is deformed or the photosensitive layer tends to peel from the substrate.

[0140] The molecular weight of the polymer having the photosensitive group and the crosslinkable group introduced therein is not particularly limited. However, it is desirable for the polymer to have a weight average molecular weight falling within a range of between 500 and 5,000,000, more desirably between 1,500 and 50,000. Where the molecular weight of the polymer is excessively low, the polymer is poor in its film forming capability, with the result that the resistance to the solvent such as the resistance to the plating solution tends to be lowered. On the other hand, where the molecular weight is excessively high, the solubility in the solvent for the coating is lowered. In addition, the coating properties are rendered poor.

[0141] In order to activate the crosslinkable compound or the crosslinkable group for allowing the crosslinking reaction to proceed, a heat treatment or energy beam irradiation is applied. For example, a vinyl group, an acryloyl group, a methacryloyl group, a maleimide group, etc. are allowed to perform the crosslinking reaction by simply applying energy beam irradiation or heating without using a catalyst or the like. Further, it is possible to further promote the crosslinking reaction by adding a catalyst such as a radical generating agent. Still further, it is possible to cure, for example, an epoxy group, a vinyl ether group, an alkoxy silyl group, an acetoxy silyl group, an etoxy silyl group and an oxime silyl group by an acidic catalyst or a basic catalyst.

[0142] It is desirable for these crosslinking reactions to have a potentiality that the reaction is caused to proceed by the treatment such as energy beam irradiation or heating because the photosensitive composition layer is formed in general by coating a substrate with a solution or the like of a photosensitive composition. If the crosslinking reaction proceeds within the solution, the solution is gelled so as to make it impossible to carry out the coating. In order to avoid such an inconvenience, it is desirable for the crosslinking reaction to have a potentiality such that the crosslinking reaction is caused to proceed by the activation applied after the coating. It is possible to impart a potentiality to the crosslinking reaction by adding a potential catalyst. In this case, a potential catalyst is activated after formation of a photosensitive composition layer so as to crosslink the crosslinkable group.

[0143] It is desirable for the potential catalyst used to be activated by energy beam irradiation or the heating. For example, it is possible to use a radical generating agent as a potential catalyst that is activated by the heat or the energy beam irradiation. Also, a photo acid generating agent and a photo base generating agent perform the function of a potential catalyst that is activated by the energy beam irradiation. As already described, it is most desirable for the crosslinking reaction to be a radical reaction. To be more specific, it is desirable to use a radical generating agent in combination with a crosslinkable compound or a crosslinkable group capable of the radical polymerization.

[0144] It is possible to use organic peroxides as the radical generating agent. The organic peroxides include, for example, ketone peroxides such as methyl ethyl ketone peroxide, cyclohexanone peroxide, methyl cyclohexanone peroxide, methyl acetoacetate peroxide, and acetyl acetone peroxide; peroxy ketals such as 1,1-bis(t-hexyl peroxy)-3,3,5-trimethyl cyclohexane, 1,1-bis(t-hexyl peroxy)cyclohexane, 1,1-bis(t-butyl peroxy)-3,3,5-trimethyl cyclohexane, di-t-butyl peroxy-2-methyl cyclohexane, 1,1-bis(t-butyl peroxy)cyclohexane, 1,1-bis(t-butyl peroxy)cyclodecane, 2,2-bis(t-butyl peroxy)butane, n-butyl-4,4-bis(t-butyl peroxy)valerate, and 2,2-bis(4,4-di-t-butyl peroxy cyclohexyl)propane; hydroperoxides such as p-menthane hydroperoxide, diisopropyl benzene hydroperoxide, 1,1,3,3-tetramethyl butyl hydroperoxide, cumene hydroperoxide, t-hexyl hydroperoxide, and t-butyl hydroperoxide; dialkyl peroxides such as □,□′-bis(t-butyl peroxy)diisopropyl benzene, dicumyl peroxide, 2,5-dimethyl-2,5-bis(t-butyl peroxy)hexane, t-butyl cumyl peroxide, di-t-butyl peroxide, and 2,5-dimethyl-2,5-bis(t-butyl peroxy)hexene; diacyl peroxides such as isobutyryl peroxide, 3,5,5-trimethyl hexanoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, succinic acid peroxide, m-toluoyland benzoyl peroxide, and benzoyl peroxide; peroxy carbonates such as di-n-propyl peroxy carbonate, diisopropyl peroxy dicarbonate, bis(4-t-butyl cyclohexyl) peroxy dicarbonate, di-2-ethoxy ethyl peroxy dicarbonate, di-2-ethyl hexyl peroxy dicarbonate, di-3-methoxy butyl peroxy dicarbonate, and di(3-methyl-3-methoxy butyl)peroxy dicarbonate; peroxy esters such as □,□′-bis(neodecanoyl peroxy)diisopropyl benzene, cumyl peroxy neodecanoate, 1,1,3,3-tetramethyl butyl peroxy neodecanoate, 1-cyclohexyl-1-methyl ethyl peroxy neodecanoate, t-hexyl peroxy neodecanoate, t-butyl peroxy neodecanoate, t-hexyl peroxy pivalate, t-butyl peroxy pivalate, 1,1,3,3-tetramethyl butyl peroxy-2-ethyl hexanoate, 2,5-dimethyl-2,5-bis(2-ethyl hexanoyl peroxy)hexane, 1-cyclohexyl-1-methyl ethyl peroxy-2-ethyl hexanoate, t-hexyl peroxy-2-ethyl hexanoate, t-butyl peroxy-2-ethyl hexanoate, t-butyl peroxy isobutyrate, t-hexyl peroxy isopropyl monocarbonate, t-butyl peroxy meleic acid, t-butyl peroxy 3,5,5-trimethyl hexanoate, t-butyl peroxy laurate, 2,5-dimethyl-2,5-bis(m-toluyl peroxy)hexane, t-butyl peroxy isopropyl monocarbonate, t-butyl peroxy 2-ethyl hexyl monocarbonate, t-hexyl peroxy benzoate, 2,5-dimethyl-2,5-bis(benzoyl peroxy)hexane, t-butyl peroxy acetate, t-butyl peroxy-m-toluyl benzonate, t-butyl peroxy benzoate, and bis(t-butyl peroxy)isophthalate; as well as t-butyl peroxy allyl monocarbonate, t-butyl trimethyl peroxide, 3,3′,4,4′-tetrakis(t-butyl peroxy carbonyl)benzophenone and 2,3-dimethyl-2,3-diphenyl butane. Particularly, the polyfunctional radical generating agents such as 2,2-bis(4,4-di-t-butyl peroxy cyclohexyl)propane and 3,3′4,4′tetra(t-butyl peroxy carbonyl)benzophenone also perform the function of a crosslinking agent and, thus, are used desirably. In addition to the peroxides, it is also possible to use azonitriles such as azobisisobutyronitrile.

[0145] However, a problem remains unsolved in the method of activating the crosslinkable compound or the crosslinkable group having a potentiality by energy beam irradiation or heating. Specifically, where the activation is performed by energy beam irradiation, it is possible for the photosensitive compound or the photosensitive group to be sensitized without any order. It is also possible for the light beam used for the light exposure for sensitizing the photosensitive compound or the photosensitive group to be absorbed by the crosslinkable compound, the crosslinkable group or the potential catalyst such as a radical generating agent so as to lower the light exposure sensitivity. Also, when heated, it is possible for the substrate to be thermally deteriorated or thermally shrunk so as to lower the dimensional stability of the pattern.

[0146] In order to overcome these problems, it is desirable to use a photosensitive compound or a photosensitive group that can be activated by the optical reaction so as to generate or eliminate an ion-exchange group and, at the same time, to activate the crosslinking reaction. It is possible to achieve simultaneously the generation or elimination of an ion-exchange group and the crosslinking reaction by using a photo acid generating agent of the radical generation type. Alternatively, it is also possible to achieve simultaneously the generation or elimination of an ion-exchange group and the crosslinking reaction by using peroxide esters.

[0147] The photo acid generating agent generating an acid upon irradiation with an energy beam includes a photo acid generating agent of a radical generation type that generates a radical simultaneously with the acid generation. In the case of using the particular photo acid generating agent, an atomic group having a protective group introduced into an ion-exchange group and a crosslinkable group capable of a radical polymerization in combination, it is possible for the irradiated portion to be crosslinked by the radical and, at the same time, it is possible for an ion-exchange group to be generated by the acid so as to achieve the plating.

[0148] The photo acid generating agent that permits the particular function described above includes, for example, triazines. The triazines include, for example, 2-[2-(5-methyl furan-2-yl)ethenyl-4,6-bis(trichloromethyl)-s-triazine, 2-[2-(furan-2-yl)ethenyl]-4,6-bis(trichloromethyl)-s-triazin e, 2-[2- (4-diethyl amino-2-methyl phenyl)ethenyl]4,6-bis(trichloromethyl)-s-triazine, 2-[2-(4-diethyl amino ethyl)amino]-4,6-bis(trichloromethyl)-s-triazine.dimethyl sulfate, 2-[2-(3,4-dimethoxy phenyl)ethenyl]-4,6-bis(trichloromethyl)-s-triazine, 2-(4-dimethoxy phenyl)-4,6-bis(trichloromethyl)-s-triazine, 2-methyl-4,6-bis(trichloromethyl)-s-triazine and 2,4,6-tris(trichloromethyl)-s-triazine.

[0149] Also, peroxy esters, i.e., peroxide esters, are capable of generating a carboxyl group of the ion-exchange group and, at the same time a radical upon irradiation with an energy beam. The radical thus generated serves to crosslink the crosslinkable compound such as a vinyl compound. Since the generation of the carboxyl group and the crosslinking are caused by a single optical reaction, the photosensitivity is not lowered by the light absorption of the crosslinkable compound. Further, since the heat treatment is not required, the thermal deterioration and the thermal shrinkage do not take place.

[0150] It is possible to use a polymer having peroxide esters introduced into the side chain as the peroxide esters. It is also possible to use polyfunctional peroxide esters having a relatively low molecular weight. Since the polyfunctional peroxide esters having a low molecular weight are changed into polyfunctional carboxylic acids, the particular polyfunctional peroxide esters were considered to elute into an alkaline electroless plating solution. However, the present inventors have found for the first time that, if a polymer capable of a radical polymerization such as polyvinyl ethylene is added, the polyfunctional peroxide esters do not elute into the alkaline electroless plating solution so as to achieve a satisfactory plating.

[0151] The reason for the capability of achieving a satisfactory plating is considered to be as follows. Specifically, the peroxide ester is sensitized to light so as to generate a carboxy radical, and the carboxy radical thus generated reacts and is coupled with a polymer so as to achieve a satisfactory plating. The polyfunctional peroxide esters of a low molecular weight are also coupled with a polymer after the light sensitization so as to be introduced into the side chain of the polymer, with the result that the elution into the plating solution is prevented. According to one embodiment of the present invention, it is possible to prepare a photosensitive composition by simply mixing a polyfunctional peroxide ester with a crosslinkable polymer having a radical reactivity. The peroxide ester group coupled with a polymer does not perform the function of an ion-exchange group. It follows that it is necessary for at least two peroxide ester groups, which are coupled with a polymer and form ion-exchange groups, to be present in a single molecule. It is necessary to synthesize the polymer having a peroxide ester introduced into the side chain every time the rate of introduction of the peroxide ester is changed. On the other hand, in the case of using polyfunctional peroxide esters having a low molecular weight, it is possible to adjust the amount of the ion-exchange group generated in the sensitizing step by simply changing the mixing ratio of the polyfunctional peroxide esters. Since it is necessary to adjust delicately the amount of the ion-exchange groups depending on the composition of the plating solution and the plating conditions, the capability of changing the amount of the ion-exchange groups by simply changing the mixing ratio is highly advantageous.

[0152] The peroxy esters include, for example, peroxides of 1-cyclohexyl-1-methyl ester, tert-butyl ester, tert-hexyl ester and 1,1,3,3-tetramethyl butyl ester of a carboxylic acid. Particularly, it is desirable to use a peroxide of tert-butyl ester in view of, for example, the storage stability. The specific polyfunctional peroxide esters include, for example, bis(tert-butyl peroxy)isophthalate (trade name of Perbutyl IF manufactured by Nippon Yushi K.K.) and 3,3′,4,4′-tetra-(tert-butyl peroxy carbonyl)benzophenone (trade name of BTTB manufactured by Nippon Yushi K.K.). Particularly, 3,3′,4,4′-tetra-(tert-butyl peroxy carbonyl)benzophenone, which can be stored under room temperature, is excellent in the storage stability and can be sensitized by various photosensitizers as described herein later.

[0153] It is also possible to use tert-butyl peroxy allyl monocarbonate (trade name of Pellomer AC manufactured by Nippon Yushi K.K.) having a peroxide ester group and a radical polymerizable group in a molecular, though this compound has a low molecular weight. In this case, the radical polymerizable group is polymerized so as to form a polymer and, thus, it is possible to prevent the elution into a plating solution.

[0154] It is also possible to use, for example, a silyl peroxide such as tert-butyl silyl peroxide as a chemical structure capable of generating an ion-exchange group and a radical simultaneously. Silyl peroxide generates a silanol group as an ion-exchange group.

[0155] The compound capable of generating an ion-exchange group and a radical simultaneously can also be used as a radical generating agent for crosslinking a photosensitive compound and a crosslinkable compound. Since an ion-exchange group is generated simultaneously with the radical generation, the mixing of the particular compound permits efficiently achieving a high sensitivity. In this case, it is desirable for the ion-exchange group generated from the photosensitive compound and the ion-exchange group generated from the radical generating agent to have the ion exchange capabilities substantially equal to each other. For example, it is desirable to use quinone diazides or o-nitrobenzyl esters of a carboxylic acid in combination with peroxide esters of a carboxylic acid. Each of these compounds generates a carboxylic acid upon irradiation with an energy beam. Alternatively, it is also possible to use o-nitrobenzyl esters of a silanol and silyl peroxide in combination. It should be noted, however, that the carboxyl group is superior to the silanol group in the adsorption capability of the catalyst nucleus. Also, in the case of using a silica glass substrate, the silanol group is not adapted for use as the ion-exchange group because a silanol group is present on the surface of the substrate.

[0156] As described above, it is desirable for the photosensitive material used in the method according to one embodiment of the present invention for manufacturing a composite member having a conductive pattern to be formed of a photosensitive composition containing a polymer having a photosensitive group for generating or eliminating an ion-exchange group and a crosslinkable group capable of a radical polymerization and a radical generating agent. It is desirable for the radical generating agent to be capable of generating an acid or an ion-exchange group. The radical generating agent generating an acid includes triazines as typical examples, and the radical generating agent generating an ion-exchange group includes peroxide esters as typical examples.

[0157] It is desirable for the photosensitive group used in combination with the radical generating agent generating an acid to be an atomic group having an ion-exchange group protected with a protective group. The protective group that can be de-protected with an acid is used. Particularly, it is desirable to use a carboxylic group, a phenolic hydroxyl group and a silanol group each having a tert-butyl group or a tetrahydropyranyl group as a protective group. It is particularly desirable to use a quinone diazide derivative group or an o-nitrobenzyl ester derivative group as a photosensitive group used in combination with a radical generating agent generating an ion-exchange group.

[0158] A desirable combination of the photosensitive composition includes a polymer and triazines used as a radical generating agent. In the polymer used in the photosensitive composition of one embodiment of the present invention, a photosensitive group selected from the group consisting of tert-butoxy carbonyl methyl group, tert-butoxy carbonyl ethyl group, tetrahydro pyranyloxy carbonyl methyl group, and tetrahydro pyranyloxy carbonyl ethyl group is introduced into the phenolic hydroxyl group of a phenol novolak resin or a cresol novolak resin. Also, a crosslinkable group selected from the group consisting of acryloyl group and methacryloyl group is introduced into the polymer.

[0159] It is also desirable to use a combination of a polymer and peroxide esters of a carboxylic acid such as 3,3′,4,4′-tetra-(tert-butyl peroxy carbonyl)benzophenone used as a radical generating agent. In the polymer contained in the photosensitive composition used in one embodiment of the present invention, a photosensitive group selected from the group consisting of naphthoquinone-1,2-diazide-4-sulfonic acid ester, o-nitrobenzyloxy carbonyl methyl group or o-nitrobenzyloxy carbonyl ethyl group is introduced into the phenolic hydroxyl group of a phenolic novolak resin or a cresol novolak resin. A crosslinkable group selected from the group consisting of an acryloyl group and a methacryloyl group is also introduced into the polymer.

[0160] It is possible to add various photosensitizers to the photosensitive composition or the photosensitive material used in the manufacturing method according to one embodiment of the present invention. It is possible to improve the sensitivity and to change in various fashions the photosensitive wavelength in accordance with the light source used by adding a photosensitizer. Where it is intended to achieve the sensitization deep inside a porous substrate, it is desirable to sensitize the photosensitive composition or the photosensitive material with an energy beam that is readily transmitted through the substrate such as a light beam having a wavelength other than the absorption wavelength of the substrate. When it comes to a porous substrate such as a polyimide substrate, light having a wavelength not longer than about 500 nm is absorbed by the substrate, making it difficult to expose the inner region of the porous substrate to light by using, for example, a g-line or an i-line. Even in this case, it is possible to achieve the sensitization to reach the inner region of the porous substrate by using a visible light photosensitizer having an absorption band in the wavelength region not shorter than 500 nm.

[0161] The photosensitizers include, for example, an aromatic hydrocarbon and a derivative thereof, a benzophenone and a derivative thereof, o-benzoyl benzoic acid ester and a derivative thereof, acetophenone and a derivative thereof, benzoin and a derivative thereof, benzoin ether and a derivative thereof, xanthone and a derivative thereof, thioxanthone and a derivative thereof, a disulfide compound, a quinone-based compound, a compound having a halogenated hydrocarbon, amines, melocyanine-based coloring matters such as 3-ethyl-5-[(3-ethyl-2(3H)-benzothiazolylidene)ethylidene]-2- thioxo-4-oxazolidinone and 5-[(1,3-dihydro-1,3,3-trimethyl-2H-indole-2-ylidene)ethylide ne]-3-ethyl-2-thioxo-4-oxazolidinone; cyanine-based coloring matters such as 3-butyl-1,1-dimethyl-2-[2[2-diphenyl amino-3-[(3-butyl-1,3-dihydro-1,1-dimethyl-2H-benz[I]indole- 2-ylidene)ethylidene-1-cyclopentene-1-yl]ethenyl]-1H-benz[I] indolium percholate, 2-[2-[2-chloro-3-[(3-ethyl-1,3-dihydro-1,1-dimethyl-2H-benz[ I]indole-2-ylidene)ethylidene]-1-cyclohexane-1-yl]ethenyl]-1 ,1-dimethyl-3-ethyl-1H-benz[e]indolium tetrafluoroborate, and 2-[2-[2-chloro-3-[(3-ethyl-1,3-dihydro-1,1-dimethyl-2H-benz[ e]indole-2-ylidene)ethylidene]-1-cyclopentene-1-yl]ethenyl]- 1,1-dimethyl-3-ethyl-1H-benz[e]indolium iodide; squalium series cyanine-based coloring matters; styryl-based coloring matters such as 2-[p-(dimethyl amino)styryl]benzothiazole, 2-[p-(dimethyl amino)styryl]naphtho[1,2-d]thiazole and 2-[(m-hydroxy-p-methoxy)styryl]benzothiazole; xanthene coloring matters such as eosine B (C.I. No. 45400), eosine J (C.I. No. 45380), cyanosine (C.I. No. 45410), Bengal rose, erythrosine (C.I. No. 45430), 2,3,7-trihydroxy-9-phenyl xanthene-6-one, and Rhodamine 6G; thiazine coloring matters such as thionine (C.I. No. 52000), azule A (C.I. No. 52005) and azule C (C.I. No. 52002); pyronine coloring matters such as pyronine B (C.I. No. 45005) and pyronine GY (C.I. No. 45005); cumarin-based coloring matters such as 3-acetyl cumarin, 3-acetyl-7-diethyl amino cumarin, 3-(2-benzothiazolyl)-7-(diethyl amino)cumarin, 3-(2-benzothiazolyl)-7-(dibutyl amino)cumarin, 3-(2-benzimidazolyl)-7-(diethyl amino)cumarin, 10-(2-benzothiazolyl)-2,3,6,7-tetrahydro-1,1,7,7-tetramethyl -1H,5H,1H-[1]benzopyrano[6,7,8-ij]quinolidine-11-one, 3-(2-(benzothiazolyl)-7-(dioctyl amino)cumarin, 3-carbetoxy-7-(diethyl amino)cumarin, 10-[3-[4-(dimethyl amino)phenyl]-1-oxo-2-propenyl]-2,3,6,7-tetrahydro-1,1,7,7-t etramethyl-1H,5H,11H-[1]benzopyrano[6,7,8-ij]quinolidine-11- one; keto cumarin-based coloring matters such as 3,3′-carbonyl bis(7-diethylamino cumarin), 3,3′-carbonyl-7-diethylamino cumarin-7′-bis(butoxy ethyl)amino cumarin and 3,3′-carbonyl bis(7-dibutyl amino cumarin); and DMC-based coloring matters such as 4-(dicyano methylene)-2-methyl-6-(p-dimethyl amino styryl)-4H-pyran and 4-(dicyano methylene)-2-methyl-6-(p-dibutyl amino styryl)-4H-pyran.

[0162] The mixing amount of the photosensitizer should fall within a range of generally between 0.001% by weight and 10% by weight, preferably between 0.01% by weight and 5% by weight, based on the amount of the compound generating or eliminating the ion-exchange group upon exposure to light.

[0163] In the method according to one embodiment of the present invention, a pattern of ion-exchange groups is formed by selectively exposing a photosensitive layer comprising the components described above to light in a pattern. Then, the crosslinkable groups in the exposed portion are crosslinked. The energy beam for activating the photosensitive compound, the photosensitive group, the crosslinkable compound and the crosslinkable group is not particularly limited. It is possible to use, for example, light rays such as ultraviolet light rays, visible light rays, and infrared light rays as well as X-rays, electron beams, □-rays, □-rays and baryon rays as the energy beam. In general, ultraviolet light, visible light and electron beam are most widely used as the energy beam. Then, metal ions or a metal is adsorbed on the pattern of the ion-exchange groups.

[0164] For allowing the metal ions, the metal compound, or the metal colloid to be adsorbed on the ion-exchange groups, a substrate having a photosensitive layer formed thereon is brought into contact with a solution of metal ions, with a solution of metal compound, or with a metal colloid solution. For bringing the substrate into contact with the solution, it is most desirable to dip the substrate in the solution. It is also possible to spray the solution onto the substrate for coating the substrate with the solution.

[0165] An aqueous solution or an alcohol solution of an organic salt or an inorganic salt of gold, silver, platinum, palladium or copper, which is reduced so as to provide a catalyst of the electroless plating, is used as the solution of the metal ions. The metal ions are adsorbed on the ion-exchange group in the photosensitive layer as paired ions. The adsorbed metal ions are used as they are as the catalyst for the electroless plating. Alternatively, the adsorbed metal ions are reduced into a metal so as to provide the catalyst for the electroless plating. The ions of the metal lower in the ionization tendency than the metal used for the plating are reduced by the ions of the plating metal in the plating solution and, thus, a particular reducing treatment need not be applied to the ions of the metal noted above. In the case of applying, for example, a copper plating, the ions of gold, platinum, palladium, etc. can be used as they are. The copper ions are reduced into fine copper particles and, then, used as the catalyst for the electroless plating. It is possible to use known reducing agents such as formaldehyde, boron sodium hydride, dimethyl amine borane, trimethyl amine borane, hydrazine, and hypophosphite such as sodium hypophosphite.

[0166] The reducing agent is used in the form of a solution such as an aqueous solution, and the reduction is achieved by dipping the substrate in the solution. Incidentally, it is desirable to remove the extra metal ions by, for example, washing the substrate with water before the reduction.

[0167] As a metal compound solution, it is possible to use a solution of a metal compound such as complex ions of a metal or an organic complex of a metal. Used in one embodiment of the present invention is a metal compound having an atomic group such as an ion-exchange group capable of adsorption on an ion-exchange group or an atomic group capable of forming a covalent bond with an ion-exchange group.

[0168] Incidentally, the metal compound is an organic metal compound having an atomic group capable of adsorption on or coupling with an ion-exchange group. An organic metal complex is mainly used as such a metal compound.

[0169] In the organic metal complex, a bonding group is introduced into an organic metal complex consisting of a ligand such as a □-diketone derivative, a bipyridine derivative, a biquinoline derivative, a phenanthroline derivative or a porphyrin derivative.

[0170] The bonding group noted above includes, for example, a nitrogen-containing aromatic derivative group such as a primary, secondary or tertiary aliphatic or aromatic amino group or a pyridyl group and an onium base such as a quaternary ammonium base or a sulfonium base. It is advisable to impart solubility in water to these onium bases. In other words, it is advisable to use these onium bases in the form of a salt with a strong acid such as a hydrochloride or a sulfate. In this case, the ion-exchange group is treated with, for example, an aqueous solution of sodium borohydride, an aqueous solution of sodium carbonate, or an aqueous solution of potassium carbonate so as to provide a sodium salt or a potassium salt. If a metal-containing compound in the form of a hydrochloride or a sulfate is allowed to act on such a sodium salt or a potassium salt, it is possible to permit the metal compound to be adsorbed efficiently on the ion-exchange group.

[0171] The adsorbed metal compound is used as it is as a catalyst for the electroless plating. Alternatively, the adsorbed metal compound is reduced so as to be converted into the elemental metal that is used as a catalyst for the electroless plating.

[0172] It is possible to use an aqueous solution of the colloid of, for example, gold, silver, platinum or palladium as the metal colloid solution. Alternatively, it is also possible to use a solution using an organic solvent such as alcohol. In view of the storage stability of the metal colloid solution, it is desirable to use as the metal colloid a protected colloid protected by a protective substance such as a surface active agent or a polymer. In many cases, the metal colloid is charged positively or negatively. The polarity of the charge can be changed by changing the protective substance. The ion-exchange group is also charged in many cases within a liquid. The metal colloid is adsorbed by the electrostatic attractive force with the ion-exchange group. The metal colloid need not be reduced and can be used as it is as a catalyst for the electroless plating. Also, in the case of a protected colloid, it is possible to improve the activity as a catalyst by removing the protective substance by an etching using an acid, an alkaline solution or a solution of an oxidizing agent.

[0173] The metal colloid solution includes, for example, a palladium hydrosol. The palladium hydrosol can be prepared, for example, as follows. In the first step, an aqueous solution of a surface active agent is added to an aqueous solution containing palladium (II) chloride and sodium chloride while vigorously stirring the aqueous solution. Then, an aqueous solution of boron sodium hydride used as a reducing agent is added to the system so as to prepare a palladium hydrosol. The surface active agent, which is not particularly limited, includes, for example, stearyl trimethyl ammonium chloride, sodium dodecylbenzene sulfonate and polyethylene glycol mono-p-nonyl phenyl ether.

[0174] It is desirable for the concentration of the metal ion solution, metal compound solution, or the metal colloid solution to fall within a range of between 0.1% by weight and 30% by weight, more desirably between 1% by weight and 15% by weight. Where the concentration is unduly low, the metal ions, the metal compound, or the colloid fails to be adsorbed in a sufficiently large amount on the ion-exchange group. Also, the adsorption rate is low. It follows that a long time is required for the adsorption. On the other hand, where the concentration is excessively high, the metal ions, the metal compound, or colloid tends to be adsorbed without any order on also the region other than the region in which the ion-exchange groups are present. As a result, it is difficult to form a satisfactory composite member. The substrate is brought into contact with the metal ion solution, the metal compound solution, or the metal colloid solution by dipping the substrate in the solution. In general, the contact time, which is not particularly limited, falls within a range of between 10 seconds and 5 hours.

[0175] It is desirable to add, for example, a surface active agent to the metal ion solution, the metal compound solution, or the metal colloid solution in order to improve the wettability of the solution with the surface of the substrate. Particularly, in the case of using a porous substrate, it is desirable to add a surface active agent in order to permit the solution to permeate deep inside the porous substrate. It is desirable to use a fluorine-based surface active agent that is unlikely to be changed chemically. A similar effect can be obtained by using a solution of a supercritical fluid of the metal ion, the metal compound solution, or the metal colloid. The supercritical fluid produces a prominent effect because the supercritical fluid is well permeable into the inner region of a fine structure such as the inner region of a porous material.

[0176] Where the plating is applied to reach the inner region of a porous substrate, a better result can be obtained by using a metal ion solution. The metal colloid has a diffusion rate within a solution lower than that of the metal ion solution, with the result that it is difficult to diffuse the metal colloid sufficiently into the inner region of the porous substrate. On the other hand, the metal ions have a high diffusion rate so as to make it possible to allow the metal ions to be adsorbed sufficiently in the inner region of the porous substrate.

[0177] After the substrate is brought into contact with the metal ion solution, the metal compound solution, or the metal colloid solution, it is desirable to apply washing so as to remove the extra metal ions, the metal compound, or the metal colloid. For example, the washing is performed with a solvent, e.g., water, equal to the solvent of the metal ions, the metal compound solution, or the colloid solution. As a result, the solution attached to the region other than the region in which the ion-exchange groups are present is removed so as to prevent the region other than the region in which the ion-exchange groups are present from being plated without any order. The washing is particularly important in the case of using a porous substrate. In the case of using a substrate low in surface irregularities in which a solution tends to be accumulated such as a plate-like flat substrate, it is possible to blow away the extra solution of metal ions, of the metal compound, or of the colloid with a gaseous stream of air or nitrogen gas by using, for example, an air knife.

[0178] In the next step, electroless plating is applied, with the metal ions, the metal compound, or the metal colloid adsorbed on the ion-exchange groups used as the catalyst nuclei, so as to form a conductive pattern. The electroless plating can be performed by bringing the substrate having the metal ions, the metal compound, or the metal colloid adsorbed thereon as the catalytic nuclei into contact with the electroless plating solution, e.g., by dipping the substrate noted above in the electroless plating solution. The electroless plating solution is not particularly limited. It is possible to use the known plating solution of, for example, copper, nickel, gold, silver or platinum. The electroless plating proceeds with the metal ions, the metal compound, or the colloid adsorbed on the ion-exchange groups acting as the catalyst, with the result that the plating can be selectively achieved on only the region in which the ion-exchange groups are present.

[0179] As described above, it is possible to manufacture a composite member having a fine conductive pattern without causing the photosensitive layer to be dissolved in the plating solution so as to be peeled off by employing the manufacturing method according to one embodiment of the present invention.

[0180] The porous substrate according to another embodiment of the present invention will now be described.

[0181] In the porous substrate according to another embodiment of the present invention, a photosensitive layer is formed on the inner surfaces of the pores of an insulating porous body without closing the pores of the porous body. A wiring board having fine vias and wiring formed thereon can be easily manufactured by applying the manufacturing method of the composite member described above to the porous substrate noted above.

[0182] It is possible for the insulating material forming the porous body to be either an organic material or an inorganic material. Further, a composite material including an organic material and an inorganic material can also be used as the insulating material forming the porous body.

[0183] A polymer material is used in general as the organic material. The polymer material includes, for example, polyolefins such as polyethylene and polypropylene; polydienes such as polybutadiene, polyisoprene, polycyclohexadiene, and polyvinyl ethylene; acrylic resins such as polymethyl acrylate and polymethyl methacrylate; a polystyrene derivative; polyacrylonitrile derivatives such as polyacrylonitrile and polymethacrylonitrile; polyacetals such as polyoxymethylene; polyesters such as polyethylene terephthalate, polybutylene terephthalate and aromatic polyesters; polyarylates; aromatic polyamide such as aramid resin and polyamides such as nylon; polyimides; epoxy resins; aromatic polyethers; polyether sulfones; polysulfides; a fluorine-containing polymer such as polytetrafluoro ethylene; polybenzoxazoles; polyphenylenes such as polyparaphenylene; polyparaphenylene benzobisoxazole derivative; polyparaphenylene vinylene derivative; polysiloxane derivative; novolak resins; melamine resins and urethane resins.

[0184] On the other hand, ceramic materials are generally used as the inorganic material. The ceramic materials include, for example, metal oxides such as silica, alumina, titania, and potassium titanate as well as silicon carbide, silicon nitride and aluminum nitride.

[0185] It is desirable for the porous body to have open cells having open portions on the surface of the porous body. It is also desirable for the open cells to be formed in the form of a three-dimensional mesh structure. Where the open cells are formed in the form of a three-dimensional mesh structure, the metal plated within the open cells is rendered continuous a three-dimensionally so as to improve the mechanical strength and the conductivity. It is desirable for the average diameter of the open cells to fall within a range of between 0.05 μm and 5 μm, more desirably between 0.1 μm and 0.5 μm. Where the diameter of the cell is unduly small, the plating solution or the like tends to fail to permeate sufficiently into the inner region of the porous body. On the other hand, where the diameter of the cell is excessively large, it is difficult to form a fine pattern of the plated metal. Also, where the porous substrate is exposed to, for example, ultraviolet light or visible light, the light beam used for the light exposure is scattered by the porous structure so as to make it difficult to achieve the patterned light exposure with a high contrast.

[0186] It is desirable for the diameters of the pores of the porous body to be uniform. It is also desirable for the porosity to fall within a range of between 20% and 95%, more desirably between 45% and 90%. If the porosity is unduly low, it is possible for the plating solution to fail to permeate sufficiently or to fail to improve sufficiently the conductivity of the pattern of the plated metal. On the other hand, if the porosity is excessively high, the porous body fails to exhibit a sufficiently high mechanical strength. Also, the dimensional stability of the porous body is lowered. It is desirable for the pores to form an open cell and to have an open portion communicating with the outside of the porous body. It is difficult for the plating solution to permeate into the closed cells that do not have open portions so as to make it difficult to achieve satisfactory plating. It is desirable for the ratio of the closed cells to the entire pores of the porous body to be not higher than 50% by volume, more desirably, not higher than 10% by volume.

[0187] The porous body includes a porous sheet having three-dimensional open cells formed in a sheet of a polymer material and a cloth or an unwoven fabric in which polymer fibers or ceramic fibers are entangled in a three-dimensional mesh-like structure. It is more desirable to use the porous sheet in view of the dimensional stability. Also, the unwoven fabric is superior to the cloth because the unwoven fabric permits controlling finely and uniformly the pore diameter.

[0188] The manufacturing method of the porous sheet is not particularly limited. For example, it is possible to manufacture the porous sheet by elongating a sheet of a crystalline polymer such as polypropylene or polytetrafluoro ethylene. It is also possible to use a porous sheet formed by utilizing the spinodal decomposition or the phase separation phenomenon such as micro-phase separation. Further, it is possible to use a porous sheet formed by the emulsion templating method using a surface active agent. Still further, it is possible to use a porous sheet prepared by loading a polymer or ceramic particles in voids of an aggregate of silica or polymer beads, followed by curing the polymer or ceramic particles and subsequently removing the beads. The particular porous sheet is reported by Y. A. Vlasov et al. in “Adv. Mater. 11, No. 2, 165, 19991” and by S. A. Johnson et al. in “Science Vol.283, 963, 1999”. It is also possible to use a porous body prepared by using an aggregate of cells or liquid bubbles in place of the beads as reported by, for example, S. H. Park et al. in “Adv. Mater. 10, No. 13, 1045, 1998” and by S. A. Jenekhe et al. in “Science Vol. 283, 372, 1999”. Further, it is possible to use a porous body prepared by employing a three-dimensional optical forming method as reported by B. H. Cumpston et al. in “Nature, vol. 398, 51, 1999” and by Campbell et al. in “Nature, vol. 404, 53, 2000”.

[0189] The cloth and unwoven fabric are formed of ceramic fibers or polymer fibers. The ceramic fibers include, for example, a silica glass fiber, an alumina fiber, a silicon carbide fiber, and potassium titanate fiber. On the other hand, the polymer fibers include, for example, fibers of a liquid crystal-type polymer and a high Tg polymer such as an aromatic polyamide fiber, and an aromatic polyester fiber; fluorine-based polymer fibers such as a PTFE fiber; polyparaphenylene sulfide fiber; aromatic polyimide fibers; and polybenzoxazole derivative fibers. It is possible to use the ceramic fiber and the polymer fiber in combination. It is also possible to use a composite fiber of a ceramic material and a polymer material. When it comes to the unwoven fabric, it is particularly desirable to use an unwoven fabric of a polymer manufactured by a melt blow method. The unwoven fabric of this type has a fine fiber diameter and a uniform pore diameter. Also, it is possible to use an unwoven fabric made of fibers of a liquid crystalline polymer such as an aramid fiber having a