Other References:
IBM Technical Disclosure Bulletin, Vol. 7, No. 10, p. 873, 03-1965, "Spring Pad for Etched-Circuit Electrical Connector", Essert. .
IBM Technical Disclosure Bulletin, Vol. 7, No. 1, p. 113, 06-1964, "Heat Conducting Vibration and Shock Mount", Panaro..
Description:
This invention relates to electrical connectors, and more particularly to an improved connector for making electrical connections between two printed circuit boards or the like in which the contact elements can be easily and cheaply manufactured with high density and close spacing.
There is a type of printed circuit connector well known to those skilled in the art which consists essentially of an elongated body of insulative material which usually has a square or rectangular cross-section. The body includes a plurality of circumferential grooves usually extending all the way around the body. A plurality of resilient electrically conductive contact members are provided, with each contact member being positioned around the body of the connector in a respective one of the aforementioned grooves. Each contact member is bent so that some portions of it normally project out of its groove and above the surfaces of the connector body. When the connector is secured against a printed circuit board, the printed circuit board depresses the contact member downwardly into its channel, that the spring action of the contact member exerts force on the circuit pads on the circuit board, thereby making positive, low resistance connections with the circuit board. Typical connectors such as were just described are shown in U.S. Pat. No. 3,173,732.
Such connectors have proven to be quite satisfactory for use in many applications. However, there is a definite lower limit of the spacing between contact members which can be provided with such connectors. As the size of electrical components and printed circuit boards has been progressively reduced, this lower limit has been met, and in many instances, exceeded. This lower limit is caused by the necessity to provide a discrete contact member, usually a wire, and a discrete shoulder of insulative material between each of the aforementioned grooves for each contact member. As the connector becomes smaller and smaller to accommodate closer and closer spacing of electrical conductots, it becomes progressively more difficult and thus more expensive, to handle and assemble the resultant fine wire contact members, and the shoulder members forming the grooves become more and more fragile and subject to breakage. There is thus a definite need for an electrical connector which has the advantages of such prior art connectors, but which can provide closer and closer contact spacing while still being relatively easy and inexpensive to manufacture.
It is accordingly an object of the present invention to provide an improved electrical connector.
It is another object of the present invention to provide an improved electrical connector in which the contact spacing can be less than the prior art connectors.
It is yet another object of the present invention to provide such an improved electrical connector which can be easily and inexpensively manufactured.
Briefly stated, and in accordance with the presently preferred embodiment of this invention, an electrical connector for making electrical connection with a series of electrical conductor on a printed circuit board or the like is provided which includes a body member having a first surface adapted to be secured adjacent the series of electrical conductors. A sheet of insulative material is provided which has a front surface and a back surface. A plurality of electrically conductive contact members are provided which are secured to and exposed from the front surface of the sheet of insulative material, and the back surface of the sheet of insulative material is secured to the first surface of the body member. The electrically conductive contact members may be plated or deposited onto the front surface of the sheet of insulative material, or they may be formed on it by conventional printed circuit techniques. Thus, extremely close spacing between the contact members can be easily and economically provided.
For a complete understanding of the present invention, and appreciation of its other objects and advantages, please refer to the following detailed description of the attached drawings, in which:
FIG. 1 shows a perspective view of an electrical connector in accordance with the present invention;
FIG. 2 shows a sectional view taken along the lines 2--2 of FIG. 1;
FIG. 3 is a sectional view similar to FIG. 2 and illustrates how the connector of FIGS. 1 and 2 interconnects electrical conductors on two printed circuit boards which are positioned parallel to each other;
FIG. 4 is cross-sectional view of an electrical connector similar to the view of FIG. 2 but which illustrates a second embodiment of the present invention; and
FIG. 5 is a cross-sectional view of a connector in accordance with another embodiment of the present invention.
FIG. 1 shows a perspective view of an electrical connector 10 in accordance with the present invention. FIG. 2 shows a sectional view taken along the lines 2--2 of FIG. 1. The following description describes FIGS. 1 and 2 together.
The connector 10 includes an elongated body member 12 having a generally rectangular cross-section. The body member 12 includes a first surface 14 and an opposed surface 16 which, as is better shown in FIG. 3 described below, are adapted to be secured adjacent respective series of electrical conductors which are to be interconnected by connector 10.
In accordance with the present invention, a sheet of insulative material 18 is provided which has its back surface secured to the first and second surfaces 14 and 16 respectively of body member 12. A plurality of generally parallel electrically conductive contact members 20 are provided which are secured to and exposed from the front surface of the sheet of insulative material 18. The sheet 18 is preferably a flexible insulative material such as any of the flexible insulative plastics well known to those skilled in the art, and the electrical contact members 20 may be formed on the front surface of the sheet 18 in any desired manner. For example, the contact members 20 may be plated or deposited onto the front surface of sheet 18, or alternatively, a film of conductive material can be formed on the front surface of sheet 18, and portions of it etched away, for example by conventional printed circuit board techniques, to leave behind the desired plurality of spaced electrically conductive contact members 20.
The back surface of sheet 18 may be secured to surfaces 14 and 16 by any desired manner. For example, the surfaces may be glued or welded together over a portion of the contact area, or a suitable wedge member (not shown) may be provided. Alternatively, the length of the sheet 18 could be made longer and wrapped around the corners of the body member 12 and secured to its back surface 22. Thus, by "secured," it is meant that the sheet 18 and the surfaces 14 and 16 are held snugly together.
A longitudinal slot or groove 24 is provided which extends along at least a portion of first surface 14 of body member 12 and an elongated tab 26 of resilient material such as rubber or the like is positioned in slot 24 which extends resiliently through the plane of surface 14 and presses against the back surface of sheet 18, thus resiliently urging sheet 18 away from the surface 14 of body member 12. A similar groove 28 is provided in second surface 16 of body member 12 and a similar pad 30 of resilient material is provided in groove 28.
FIG. 3 shows a cross-sectional view of the electrical connector 10 of FIGS. 1 and 2 being used to provide electrical interconnection between a first series of electrical conductors 32 on a first printed circuit board 34 and a second series of electrical conductors 36 on a second printed circuit board 38. As is shown in FIG. 3, the first surface 14 of connector 10 is secured against the first series of electrical conductors 32 by any suitable means (not shown in the Figure), and the second surface 16 of connector 10 is secured against the second series of electrical conductors 36. Each of the contact members 20 provides electrical connection between one of the electrical conductors 32 and a respective one of the electrical conductors 36. Secure electrical connection between the contact members 20 and the electrical conductors 32 and 36 is assured by the resilient pads 26 and 30, which are compressed downwardly into their respective grooves and push back on the back surface of sheet 18 to provide adequate pressure between the contact members 20 and the electrical conductors 32 and 36.
Those skilled in the art will appreciate that the spacing between contact members 20 on sheet 18 is limited only by the state of the printed circuit art, and accordingly much closer spacing between adjacent contact members can be provided than the prior art connectors described above which require an individual wire and individual shoulder member between adjacent wires. Thus, the connector 10 of FIGS. 1 through 3 can be used to provide interconnection between printed circuit boards on which the spacing between adjacent conductors is too small to permit the use of prior art connectors. Further, as the state of the printed circuit art progresses to provide smaller and smaller circuits and circuit boards, the same advances in the art can be used with the present invention to provide smaller and smaller connectors, since in each case the printed circuit board and the connector are subject to the same state of the art limitations. In addition, those skilled in the art will appreciate and be pleased by the simplicity of manufacture and the economies of the connector of the present invention.
As was shown in FIG. 3 above, the connector 10 of FIGS. 1 and 2 is used to provide electrical interconnection between two printed circuit boards which are mounted in parallel relative to each other. Such connectors are known to those skilled in the art as 180° connectors. The present invention is equally useful in the type of connectors known to those skilled in the art as 90° connectors which are used to interconnect two printed circuit boards which are positioned at substantially right angles to each other. FIG. 4 shows a cross-sectional view of such a 90° connector 40 which embodies the present inventnion. The connector 40 includes an elongated body member 42 having a substantially square or rectangular cross-section, a first contact surface 44 and a second contact surface 46, each of which are adapted to be secured against a respective series of electrical conductors on a printed circuit board or the like. Now, instead of being opposed surfaces as in the case of the connector 10 of FIGS. 1 through 3, the surfaces 44 and 46 are adjacent surfaces which make substantially right angles with each other.
In other respects, the connector 40 is identical to the connector 10 of FIGS. 1 through 3. A sheet of insulative material 48 is provided whose back surface is secured to the surfaces 44 and 46. A plurality of electrically conductive contact members 50 are provided on the front surface of sheet 48 to make the actual electrical interconnection between the series of electrical conductors. A longitudinal groove 52 is provided in first surface 44 and a resilient pad 54 is provided in this groove which extends resiliently through the plane of surface 44 to urge the sheet 48 and contact members 50 away from surface 44. Similarly, a groove 56 and resilient pad 58 are provided in surface 46 to urge sheet 48 and contact members 50 away from this surface. The connector 40 is used to interconnect circuit boards mounted at right angles to each other in the manner well known to those skilled in the art.
FIG. 5 shows a cross-sectional view of an electrical connector in accordance with another embodiment of the present invention. The connector 60 of FIG. 5 is generally similar to the connectors of FIGS. 1 and 2 in that the connector 60 includes a body member 62 having a generally rectangular cross-section and having opposed first and second surfaces 64 and 66 respectively which are adapted for making electrical connection with a series of electrical conductors on a pair of printed circuit boards in the manner generally shown in FIG. 3 above. The connector 60 includes a sheet of insulative material 68 which has its back surface secured to the first and second surfaces 64 and 66 respectively of body member 62 and a plurality of generally parallel electrically conductive contact members 70 which are secured to and exposed from the front surface of the sheet of insulative material 68.
Again, as in the case of the earlier described embodiments, a pair of grooves 72 and 74 are provided in first and second surfaces 64 and 66 respectively in which are positioned resilient members to urge the back surface of flexible member 64 away from the surfaces 64 and 66. However, in this embodiment, the resilient members 76 have a generally V shaped cross-section having a first leg portion 78 and a second leg portion 80. Again, the resilient members 76 are formed from a suitable resilient material such as rubber.
As in the case of the embodiment of FIGS. 2 and 3, the cross-sections of the grooves 72 and 74 and the resilient members 76 are chosen such that, when one of the resilient members 76 is in its relaxed state, such as is shown in FIG. 5, the first leg portion 78 lies within the groove 74 and the second leg portion 80 extends through the surface 66 in contact with the back surface of flexible insulative member 68. When the resilient members 76 are compressed (not shown in FIG. 5), the second leg portion 80 is also compressed back into the groove 74, and the resilient member 76 is entirely contained within the groove 74 at this time. Also at this time, the compressed leg portions now exert additional pressure on the back surface of the flexible sheet 68.
The embodiment of FIG. 5 has an advantage over that of FIGS. 2 and 3 in that, when the V shaped cross-sectional member is compressed down into the groove, its motion has a component in the direction parallel to the surface 66 of connector 60, and this component of motion provides a superior wiping action to assure better contact between the electrical contact members 70 and the series of electrical conductors on a printed circuit board or the like with which electrical connection is being made by the connector 60.
The invention is thus disclosed and the presently preferred embodiment described in detail. However, it is not intended that the invention be limited to these shown embodiments. Instead, many modifications will occur to those skilled in the art which lie within the spirit and scope of the invention. For example, those skilled in the art are capable of devising any number of satisfactory means for providing a resilient force on the back of the insulative sheet. For example, protuberances could be molded directly into the contact surfaces of the body members of the connector. If desired, the protuberances could be undercut to increase their resilience and slots could be provided between adjacent protuberances to provide individual pressure pads for each electrical contact on the front surface of the insulative sheet. Alternatively, the body member could be formed from sheet metal or the like and slots could be provided in the sheet metal surfaces to form tines which could be bent outwardly to provide pressure pads for each contact member. It is thus intended that the invention be limited in scope only by the appended claims.