ELECTRICAL CONNECTOR MEANS

Abstract: An improved connector (10) for attaching a mother board (14) to a daughter board (12) has a slotted housing (15), a slotted elastomeric member (28) disposed within the housing (15), and a flexible circuit (34) with numerous conductors (45) thereon wrapped around the elastomeric member (28) with its two free ends extending partially ac­ cross the slot (29) of the elastomeric member (28). When the daughter board (14) is inserted into the housing (15), it deflects the free ends of the flexible circuit (34) into the slot (29) of the elastomeric member (28). The elastomeric member (28) has a portion (30) projecting out of the hous­ ing (15) such that, when the housing (15) is fastened to the mother board (14), the elastomeric member (28) is com­ pressed causing it to exert more pressure on the electrical conductors (45) of the flexible circuit (34) as they contact connector pads (53, 55) of the mother board (14).

Description: Technical Field The present invention is related to electrical connector means, and is more particularly related to right angle electrical connectors for making multiple electrical connections between a daughter board and a mother board. Background Art A connector of this kind is described in United States Patent Application No. 4,552,420. This connector has a pair of connector portions assembled in an operative relationship and each comprising a core formed of a dielectric material around which is wrapped a flexible circuit. The flexible circuit is provided on each side with an array of conduction tracings adapted to interconnect an array of conduction paths on a daughter board with corresponding ones of an array of conduction paths disposed on a mother board, when the daughter board is inserted between the connector portions. A pair of springs is provided to impose biasing forces on the flexible circuit to ensure electrical contact between each of the set of conduction tracings thereon and the corresponding conduction paths on the two boards. The disadvantages of this arrangement are that it is rather complex and is difficult to assemble. Disclosure of the Invention It is an object of the present invention to provide a right angle electrical connector which is simple in construction, inexpensive and reliable in operation. Thus, according to the invention, there is provided an electrical connector means for connecting a first circuit board to a second circuit board substantially at right angles to each other, in which a flexible circuit means having conductors at the surface thereof is provided to interconnect conductors of said first circuit board with conductors of said second circuit board, characterized by a housing adapted to be secured to said second circuit board, said housing defining an open ended chamber having first and second opposed side walls and an end wall which is remote from the open end and which has a slot therein for receiving an edge of said first circuit board, and an elastomeric member, having a recess in alignment with said slot, and disposed in said chamber such that part thereof projects out of said open end, said flexible circuit means being wrapped around said elastomeric member and having first and second free ends each extending at least partially across said recess and also having an intermediate portion extending over the projecting part of said elestomeric member, and first and second portions of said flexible circuit means being trapped between said elastomeric member and said first and second side walls, whereby, when said first circuit board is inserted in said slot and said housing is secured to said second circuit board, the free ends of said flexible circuit means are deflected into said recess and secured electrical contact is made between the conductors of said flexible circuit means and the conductors of said first and second circuit boards, by virtue of compression of said elastomeric member between said first circuit board and said side walls of said chamber, and between said second circuit board and said end wall of said chamber. Brief Description of the Drawings Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a side view of a daughter board connected to a mother board by an electrical connector of the present invention; Fig. 2 is a simplified top view of a housing member of the electrical connector of Fig. 1; Fig. 3 is a simplified cross sectional view of one embodiment of the electrical connector according to the present invention; Fig. 4 is a cross sectional view of the electrical connector, as shown in Fig. 3, engaged with the edge of a daughter board; Fig. 5. is a cross sectional view of the electrical connector, as shown in Fig. 4, engaged with the edge of a daughter board and fastened to a mother board for making electrical connections therebetween; Fig. 6 is a top view of a flexible circuit of the connector of Fig. 1, wherein the flexible circuit has been rolled out flat; Fig. 7 is a perspective view of a daughter board connected to a mother board by an electrical connector according to one embodiment of the present invention, wherein portions of the electrical connector have been broken away to show its internal construction; Fig. 8 is a simplified cross sectional view of an electrical connector according to a first alternative embodiment of the invention; Fig. 9 is a cross sectional view of the electrical connector, as shown in Fig. 8, engaged with the edge of a daughter board; Fig. 10 is a cross sectional view of the electrical connector, as shown in Fig. 9, engaged with the edge of a daughter board and fastened to a mother board for making electrical connections therebetween; Fig. 11 is a perspective view of a daughter board connected to a mother board by an electrical connector according to the first alternative embodiment of the present invention, wherein portions of the electrical connector have been broken away to show its internal construction; Fig. 12 is a simplified cross sectional view of an electrical connector according to a second alternative embodiment of the invention; Fig. 13 is a cross sectional view of the electrical connector, as shown in Fig. 12, engaged with the edge of a daughter board; Fig. 14 is a cross sectional view of the electrical connector, as shown in Fig. 13, engaged with the edge of a daughter board and fastened to a mother board for making electrical connections therebetween; and Fig. 15 is a perspective view of a daughter board connected to a mother board by an electrical connector according to the second alternative embodiment of the present invention, wherein portions of the electrical connector have been broken away to show its internal construction. Best Mode for Carrying Out the Invention Referring now to Figs. 1 and 2, there is shown a connector 10 of the present invention for making electrical connection between a daughter board 12 and a mother board 14. The connector 10 includes a connector housing 15, illustrated in Fig. 1 with a portion thereof broken away to expose a portion of the daughter board 12 therein. As seen best in Fig. 2, a slot 16 runs the entire length of the connector housing 15 and communicates with a plurality of chambers 17 into each of which there has been placed an elastomeric member 28. A plurality of solid portions 22 spaced along and at the ends of the housing 15 define the ends of the chambers 17. The top of each chamber 17 extends up to the slot 16 such that the edge of the daughter board 12 may be inserted into the top portion of each chamber 17. The daughter board 12 penetrates through the slot 16 and into each respective chamber 17 until further penetration is stopped by the top surface of the solid portions 22. The solid portions 22 not only serve as stops for the edge of the daughter board 12, but also receive a plurality of screws 25 for connecting the mother board 14 to the connector housing 15, as will be explained. Figs. 3, 4 and 5 are simplified cross sectional views of the connector assembly 10 showing how the connector 10 may be assembled for making electrical connections between the daughter board 12 and mother board 14. Each elastomeric member 28 has an upper slot 29 which communicates with the slot 16 in the connector housing 15. The lower portion 30 of each elastomeric member 28 has two semi-cylindrical portions 35 and 36 separated by a channel 33. The two semi-cylindrical portions 35 and 36 are axially parallel to each other and are substantially equal in all dimensions including the extension of each below the bottom 39 of the connector housing 15. The semi-cylindrical portions 35 and 36 of the elastomeric members 28 will be compressed and deformed as the mother board 14 is fastened to the connector housing 15, as will be explained. The elastomeric members 28 may be fabricated of compressible silicone material available from the General Electric Company under the designation SE6140 and having a durometer rating of 40. A flexible circuit 34, which can be readily manufactured from commercially available materials, is positioned around the periphery of each elastomeric member 28 and trapped between the elastomeric member 28 and the walls of the chamber 17. The flexible circuit 34 has a fold 37 permanently formed along the length of its central strip portion. This fold is positioned partially within the channel 33. The free-ends 31 and 32 of the flexible circuit 34 initially extend in an overlapping fashion across the slot 29 of the elastomeric member 28. Fig. 4 illustrates a daughter board 12 having one edge inserted into the slot 16 of the connector housing 15 and extending into the slot 29 of the elastomeric member 28. With the edge of the daughter board 12 in the slot 29, the free-ends 31 and 32 are displaced downwards and trapped between the sides of the daughter board 12 and the walls of the slot 29 as the daughter board 12 is inserted into the slot 29. It will be noted that the width of the slot 29 is at least ten per cent less than the thickness of the daughter board 12 such that, as the edge of the daughter board 12 is inserted into the slot 29, the elastomeric material is compressed making a tight connection between the sides of the daughter board 12 and the free-ends 31 and 32. A wiping action between the conductors on the flexible circuit and the edge connector pads of the daughter board 12 is also provided as the edge of the daughter board 12 is inserted into the slot 29. Referring to Fig. 5, the mother board 14 is connected to the housing member 15 by the plurality of screws 25 which pass through holes 38 in the mother board 14 and are screwed into the solid portions 22 of the housing member 15 (see Figs. 1 and 2). As the mother board 14 is drawn into a tight engagement with the connector housing 15, the semi-cylindrical portions 35 and 36 of the elastomeric members 28 are compressed against the sides of the chamber 17 and the top of the mother board 14. The semi-cylindrical portions 35 and 36 not only become compressed as they are forced into the smaller volume of the chamber 17, but they also undergo deformation into the volume of the channel 33. This deformation pushes the fold 37 of the flexible circuit 34 between the semi-cylindrical portions 35 and 36, and causes the adjoining portions of the flexible circuit 34 to sweep across the top of the mother board 14 with a wiping action. Each semi-cylindrical portion 35 and 36 traps a portion of the flexible circuit 34 against the mother board connector pads and secures a portion of the flexible circuit 34, which is adjacent to the fold 37, into the now diminished channel 33. Fig. 6 illustrates the flexible circuit 34 in a rolled-out-flat condition before it has been formed around the elastomeric members 28 (see Figs. 3-5). The flexible circuit 34, which can be formed of polyimide or other similar commercially available material, has a number of opposed extending panels 40 and 41 extending from a central strip 42. The extending panels 40 and 41 are sized such that, when they are positioned around opposite sides of individual elastomeric members 28, the extending panels 40 and 41, and associated elastomeric members 28, will fit into the chambers 17 of the connector housing 15 (see Figs. 1 and 2). The center strip 42 includes holes 44 located on its ends and along its length between the pairs of extending panels 40 and 41 for registering with the holes 38 through the mother board 14. It will thus be understood that the screws 25 pass through the holes 38 and 44 into the solid portions 22 of the connector housing 15 when the mother board 14 is fastened to the connector housing 15, as described in connection with Fig. 5. The flexible circuit 34 has etched, gold plated copper conductors 45 on the extending panels 40 and 41 extending partially into the connecting strip 42 and ending at reference numbers 46 and 47. This allows a separate circuit on each side of the daughter board 12 to be connected to a separate circuit on the mother board 14, as will be discussed in connection with Fig. 7. It will be understood that, rather than a single integrated structure as seen in Fig. 6, flexible circuit 34 could be replaced with separate and unjoined individual flexible circuits, each having paired extending panels 40 and 41 and each for being placed around one of the elastomeric members 28 in one of the chambers 17. Fig. 7 is a perspective view of the connector 10 of the present invention with the housing 15 broken away to show the electrical connections between edge connector pads 52 leading to electronic components, such as integrated circuits (ICs) 48 on the daughter board 12, and printed circuit connector pads 53 and 55 on the mother board 14. The daughter board 12 has a first side 50 and a second side 51, each having separate edge connector pads 52 thereon. The mother board 14 may include two separate printed circuits, with one of the two circuits connected to pads 53 and the other to pads 55. In the illustrated embodiment of Fig. 7, the edge connector pads 52 of the circuit on side 50 of the daughter board 12 are connected to the connector pads 53, and the separate edge connector pads (not shown) on side 51 are connected to the connector pads 55. As discussed in connection with Fig. 6, the flexible circuit 34 around the elastomeric members 28 includes gold plated conductors 45 on each of the extending panels 40 and 41. The conductors 45 may be interrupted at lines 46 and 47 such that there is no electrical continuity between the conductors 45 on extending panel 40 and the conductors 45 on extending panel 41 (not shown in Fig. 7) of the flexible circuit 34. The edge connector pads 52 and the printed circuit connector pads 53 and 55 are 1.27 millimetre wide on 2.54 millimetres center-to-center spacing. The gold plated conductors 45 on the flexible circuit 34 are 0.254 millimetres wide on 0.508 millimetres center-to-center spacing. Thus, as shown in Fig. 7, at least two of the conductors 45 lead from each of the edge connector pads 52 to the connector pads 53 and 55 which are to be electrically connected. Figs. 8, 9 and 10 are simplified cross sectional views of a connector 10′ showing an alternative way for making electrical connections between the daughter board 12 and mother board 14. The connector 10′ includes elastomeric members 28, each sized to be fitted into the upper portion of one of the chambers 17 of the connector housing 15. In this alternative embodiment, each chamber 17 widens substantially at the bottom 39 of the housing 15. Each elastomeric member 28 has an upper slot 29 which communicates with the slot 16 in the connector housing 15. The lower portion 30 of each elastomeric member 28 has two semi-cylindrical portions 35 and 36 separated by a channel 33. The two semi-cylindrical portions 35 and 36 are axially parallel to each other and are substantially equal in all dimensions including the extension of each below the bottom 39 of the connector housing 15. The semi-cylindrical portions 35 and 36 of the elastomeric members 28 will be compressed and deformed as the mother board 14 is fastened to the connector housing 15, as will be explained. The elastomeric members 28 may be fabricated as described previously with regard to Fig. 3. The same type of flexible circuit 34 is positioned around the periphery of each elastomeric member 28 and trapped between the elastomeric member 28 and the upper walls of the chamber 17. The flexible circuit 34 has a fold 37 permanently formed along the length of its central strip portion. This fold is positioned partially within the channel 33. The free-ends 31 and 32 of the flexible circuit 34 initially extend across the slot 29 of the elastomeric member 28. Fig. 9 illustrates a daughter board 12 having one edge inserted into the slot 16 of the connector housing 15 and extending into the slot 29 of the elastomeric member 28. With the edge of the daughter board 12 in the slot 29, the free-ends 31 and 32 are displaced downwards and trapped between the sides of the daughter board 12 and the walls of the slot 29 as the daughter board 12 is inserted into the slot 29. It will be noted that the width of the slot 29 is at least ten per cent less than the thickness of the daughter board 12, such that as the edge of the daughter board 12 is inserted into the slot 29, the elastomeric material is compressed, thereby making a tight connection between the sides of the daughter board 12 and the free-ends 31 and 32. A wiping action between the conductors on the flexible circuit and the edge connector pads is also provided as the edge of the daughter board 12 is inserted into the slot 29. Referring to Fig. 10, the mother board 14 is connected to the housing member 15 by the plurality of screws 25 which pass through holes 38 in the mother board 14 and are screwed into the solid portions 22 of the housing member 15 (see Figs. 1 and 2). As the mother board 14 is drawn into a tight engagement with the connector housing 15, the semi-cylindrical portions 35 and 36 of the elastomeric members 28 are compressed against both the upper sides and the lower widened sides of the chamber 17,as well as the top of the mother board 14. The semi-cylindrical portions 35 and 36 not only become compressed as they are forced into the smaller volume of the chamber 17, but they also undergo deformation. The semi-cylindrical portions 35 and 36 deform into the volume of the lower, widened sides of the chamber 17 and into the volume of the channel 33. This deformation traps the flexible circuit 34 between the semi-cylindrical portions 35 and 36 and the top of the mother board 14. The force of the semi-cylindrical portions 35 and 36 flattens the conductors of the flexible circuit 34 upon the connector pads of the mother board 14 and thereby increases the amount of conductor area for electrical contact. The flexible circuit 34 used in the alternative embodiment shown in Figs. 8 through 11 is substantially identical to the flexible circuit 34 described previously in regard to Fig. 6 and, therefore, the details about the flexible circuit 34 are not further described here. Fig. 11 is a perspective view of the connector 10′ according to the present invention with the housing 15 broken away to show the electrical connections between edge connector pads 52 leading to electronic components, such as integrated circuits (ICs) 48 on the daughter board 12, and printed circuit connector pads 53 and 55 on the mother board 14. The daughter board 12 has a first side 50 and a second side 51, each having separate edge connector pads 52 thereon. In the illustrated embodiment of Fig. 11, the edge connector pads 52 of the circuit on side 50 of the daughter board 12 are connected to the connector pads 53, and separate edge connector pads on side 51 (not shown) are connected to the connector pads 55. As discussed in connection with Fig. 6, the flexible circuit 34 around the elastomeric members 28 includes gold plated conductors 45 on each of the extending panels 40 and 41. The conductors 45 may be interrupted at lines 46 and 47 such that there is no electrical continuity between the conductors 45 on extending panel 40 and the conductors 45 of the extending panel 41 (not shown in Fig. 11) of the flexible circuit 34. The edge connector pads 52 and the printed circuit connector pads 53 and 55 are .050 inches wide on .100 inch center-to-center spacing. The gold plated conductors 45 on the flexible circuit 34 are .010 inches wide on .020 inch center-to-center spacing. Thus, as shown in Fig. 11, at least two of the conductors 45 lead from each of the edge connector pads 52 to the connector pads 53 and 55 which are to be electrically connected. Figs. 12, 13 and 14 are cross sectional views of a portion of the connector assembly 10″ showing yet another way that the connector assembly 10″, may be assembled for making electrical connections between the daughter board 12 and mother board 14. The connector assembly 10″ includes elastomeric members 28, each sized to be fitted into one of the chambers 17 of the connector housing 15. In this embodiment, the lower portion 30 of each elastomeric member 28 has a rounded end instead of the two semi-cylindrical portions 35 and 36 of the previous embodiments. The rounded end extends below the bottom 39 of the connector housing 15 such that the elastomeric members 28 will be compressed when the mother board 14 is fastened to the connector housing 15. When the edge of the daughter board 12 is inserted into the slot 29 as shown in Fig. 13, the elastomeric material is compressed making a tight connection between the sides of the daughter board 12 and the free-ends 31 and 32. A wiping action is also provided as the edge of the daughter board 12 is inserted into the slot 29. Referring to Fig. 14, the mother board 14 is connected to the housing member 15 by the plurality of screws 25 which pass through holes 37 in the mother board 14 and are screwed into the solid portions 22 of the housing member 15 (see Figs. 1 and 2). As the mother board 14 is drawn into tight engagement with the connector housing 15, the lower portions 30 of the elastomeric members 28 are compressed, tightly trapping the flexible circuit 34 between the elastomeric members 28 and top of the mother board 14. Fig. 15 is a perspective view of the connector 10″ of the present invention represented in a similar manner as the embodiments shown in Figs. 7 and 11 and with the same reference numerals. While the elastomeric member 28 of this embodiment is simpler than those of the previous embodiments, the drawback of this design is in that most of the pressure of the semi-cylindrical portions of the elastomeric member 28 impinges upon the non-conducting strip of the mother board 14 defined by the lines 46 and 47, and not against the connector pads 53, 55. It will be seen that the disclosed embodiments of the present invention are inexpensive in that pins and pin connections are not required. Furthermore, electrical connections will be made even if the connector assemblies 10, 10′ or 10″ and/or the flexible circuit 34 therein, are slightly skewed or offset. The connector assemblies 10, 10′ and 10″ also provide for right angle contact between a mother board 14 and daughter board 12, which does not require expensive, often unused, mating connectors on a mother board, allows for right angle contact between two circuits on the mother board 14 with two circuits on the daughter board 12, allows for the changing of the daughter board 12 without removal of the connector assembly, and provides for ease of interconnect changes by revising the conductor pattern on the flexible circuit 34. It will also be understood that a connector assembly need not be added to the mother board 14 until it is desired to add a daughter board 12. Thus, the connector assemblies 10, 10′ or 10″ need not be added to the mother board 14 in anticipation of additional daughter boards 12 (such as additional memory boards) being added at a later time, but may be quickly and easily added with only a screwdriver at the time additional daughter boards 12 are actually added. Furthermore, it will be understood that, if printed circuits are printed on both sides of the mother board 14, a connector assembly 10, 10′ or 10″ may be attached to both major surfaces of the mother board 14 to provide for the connection of daughter boards 12 on each side of the mother board 14, if desired.

Claims: Electrical connector means (10) for connecting a first circuit board (12) to a second circuit board (14) substantially at right angles to each other, in which a flexible circuit means (34) having conductors (45) at the surface thereof is provided to interconnect conductors (52) of said first circuit board (12) with conductors (53,55) of said second circuit board (14), characterized by a housing (15) adapted to be secured to said second circuit board (14), said housing (15) defining an open ended chamber (17) having first and second opposed side walls and an end wall which is remote from the open end (39) and which has a slot (16) therein for receiving an edge of said first circuit board (12), and an elastomeric member (28), having a recess (29) in alignment with said slot (16), and disposed in said chamber (17) such that part (30) thereof projects out of said open end (39), said flexible circuit means (34) being wrapped around said elastomeric member (28) and having first and second free ends (31,32) each extending at least partially across said recess (29) and also having an intermediate portion extending over the projecting part of said elastomeric member (28), and first and second portions of said flexible circuit means (34) being trapped between said elastomeric member (28) and said first and second side walls, whereby, when said first circuit board (12) is inserted in said slot (16) and said housing (15) is secured to said second circuit board (14), the free ends (31,32) of said flexible circuit means (34) are deflected into said recess (29) and secure electrical contact is made between the conductors (45) of said flexible circuit means (34) and the conductors (52,53,55) of said first and second circuit boards (12,14), by virtue of compression of said elastomeric member between said first circuit board and said side walls of said chamber, and between said second circuit board and said end wall of said chamber. Electrical connector means according to claim 1, characterized in that the projecting part (30) of said elastomeric member (28) includes first and second axially extending, semi-cylindrically, portions (35,36) separated by a channel (33), a middle portion of said flexible circuit means (34) being disposed partially within said channel (33). Electrical connector means according to claim 2, characterized in that said chamber (17) has a widened portion adjacent its open end (39), whereby said projecting part of said elastomeric member (28), and said flexible circuit means (34) surrounding it, are deformed into said widened portion of the chamber (17) and into the channel (33) as the housing (15) is secured to said second circuit board (14), increasing the force and the contact area between the conductors (45) of the flexible circuit means (34) and the conductors (53,55) of said second circuit board (14) to improve the electrical connection therebetween. Electrical connector means according to either claim 2 or 3, characterized in that, as the housing (15) is fastened to said second circuit board (14), the flexible circuit means (34) and the first and second semi-cylindrical portions (35,36) are deformed into the channel (33) in a sweeping motion, wiping the conductors (45) of the flexible circuit means (34) against the conductors (53,55) of said second circuit board (14) to improve the electrical connection therebetween. Electrical connector means according to claim 1, characterized in that electrical contact with each conductor (52) of said first circuit board (12) and with each conductor (53,55) of said second circuit board (14) is effected by at least two conductors (45) of the flexible circuit means (34). Electrical connector means according to claim 1, characterized in that said housing (15) has means (22) for receiving a fastener (25), and said flexible circuit means (34) has a hole (44) therein for allowing the passage of said fastener (25) to the fastener receiving means (22), and in that said second circuit board (14) has a hole (38) therein for allowing the passage of the fastener (25) to said receiving means (22) enabling said connector means to be secured on to said second circuit board (14) for connection to said first circuit board (12). Electrical connector assembly for connecting two circuit boards (12) to a common circuit board (14), comprising one connector means claimed in any one of the preceding claims secured to each of the opposite major surfaces of said common circuit board (14).

Inventors: PORTER, WARREN, WESLEY
Applicants: NCR INTERNATIONAL INC.
Application year: 1988
Main classification: H01R23
IPC codes: H01R12, H01R13