Flexible circuit and connector

Abstract: A flexible circuit (1) provided with at least one connector for connecting an electrical component (25) to corresponding con­ ductors of the flexible circuit. The connector consists of two parallel contact strips (5) from insulating flexible material, which are attached to the flexible circuit. The surfaces of the contact strips (5) facing each other have contact surfaces (6, 7) which are electrically connected to the corresponding conductors (3, 2) of the flexible circuit (1). The connector further consists of a positioning block (15) from insulating material, which is provided with holes into which the connecting pins (21, 22) of the electrical component (25) can be inserted. Grooves (16, 17) in which the contact strips lie are provided in the side faces, adja­ cent to the holes, of the positioning block and have a depth which is greater than the minimum distance between the wall of a hole and the adjacent side face of the positioning block. A clamping spring (37) which presses the contact strips (5) towards each other is provided.

Description: The invention relates to a flexible circuit provided with at least one connector for connecting an electrical component to corresponding conductors of the flexible circuit. The use of flexible circuits and corresponding connectors is known from the British document GB-A-1 200 801 The use of electronics in automobile technique is not limited solely to ignition control or fuel regulation and brake energization, but its use in the electrical switching of the gear box is also to be recommended. It has been found that this makes the design more compact and more gear change functions can be carried out. For this purpose it is, however, important that the electrical control can be accommodated in this compact construction and is resistant to the large differences in temperature. The connection technique should also be resistant to these temperature variations and also to the fluids used in this connection. In order to achieve a compact construction, use is made of a flexible circuit made of a base material which is resistant to these temperatures and fluids. If required, said flexible circuit may be of double-sided construction. Provided on the base material or embedded therein are conductors produced by known etching techniques and in accordance with a layout which is determined by the control circuit. In order, however, to achieve a connection to an electrical component, for example a control relay, electrical conductors and crimp connections are used which often give rise to faults and large contact resistances, particularly in the long term. The object of the invention is to provide a flexible circuit of the type mentioned in the introduction in which the problems mentioned are avoided. In order to achieve this object, the invention is characterized in that the connector is formed by two contact strips made of flexible insulating material which are attached to the flexible circuit and which extend substantially parallel to each other and orthogonally to the flexible circuit in the assembled condition and have, on the surfaces facing each other, contact surfaces which are electrically connected to the corresponding conductors of the flexible circuit, and by a positioning block which is made of insulating material and is provided with holes into which the connecting pins of the electrical component can be inserted, in that grooves in which the contact strips lie are provided in the side faces, adjacent to the holes, of the positioning block, which grooves have a depth which is greater than the minimum distance between the wall of a hole and the adjacent side face of the positioning block, and in that a clamping spring which presses the contact strips towards each other is provided. This achieves a very simple connection which requires little space. Moreover, this connection gives less rise to faults while ensuring a low contact resistance even in the long term. Moreover, the manufacture of the diverse components of the connector and also the provision thereof on the flexible circuit is much less labour-intensive and therefore cheaper than the connections used hitherto. The electrical connection between the contact surfaces of the contact strips and the corresponding conductors and the mechanical connection between the contact strips and the flexible circuit is preferably achieved in that the contact strips extend parallel to, and at a distance from, an edge of the flexible circuit and are connected thereto by a connecting strip on which connecting conductors are provided which are electrically connected, on the one hand, to the contact surfaces of the contact strips and, on the other hand, to the corresponding conductors of the flexible circuit. The clamping spring is preferably composed of a strip which is in contact with, and extends in the same direction as, the connecting strip of the flexible circuit and of two resilient legs formed onto either side of the strip which extend transversely to the plane of the strip and in the direction of the grooves of the positioning block. As a result, the clamping spring is firmly in contact with the positioning block. In an embodiment, the strip of the clamping spring is provided, at the end which is furthest from the flexible circuit, with a hook-shaped element which engages in a recess in the face of the positioning block which faces away from the flexible circuit. The clamping spring is fixed on the positioning block by the gripping action. The fixing is improved still further in that the strip of the clamping spring is provided, at the end which is nearest to the flexible circuit, with a hole for receiving a projecting part of the positioning block. In an embodiment, the spacing of the legs of the clamping spring at the free end in the disengaged state is less than the distance between the bottoms of the grooves of the positioning block. In a further embodiment, the spacing of the legs of the clamping spring near the strip is greater than the distance between the bottoms of the grooves of the positioning block. The special shaping of the legs of the spring clamp ensures a good contact pressure, while the clamping spring is easy to fit. Preferably, the contact strips are provided at the free ends with transversely extending projecting parts which are received in corresponding recesses in the positioning block. A good fixing of the contact strips is achieved by the gripping action between the projecting parts and the recesses. The contact pins of a component are better held in place in that the dimension of the positioning block is greater in the direction of the groove than the length of the groove. The invention will be explained in more detail below by reference to the drawings. In the drawings: Figure 1 shows an embodiment of the flexible circuit according to the invention; Figures 2a, b and c show components of the connector of the flexible circuit; Figure 3 shows a section through the assembled connector; Figure 4 shows another embodiment of the connector with the components disassembled; Figures 5 and 6 show sections through the embodiment of Figure 4; Figure 7 shows a flexible circuit fitted on a gear box. The flexible circuit comprises a flexible sheet-like base element 1 made of electrically insulating material. The material of said base element is resistant to the prevailing operating temperatures and the fluids used. Conductors 2 and 3 are provided on the base material or embedded therein by means of known etching techniques. Preferably, the flexible circuit is of double-sided construction. The pattern of the other conductors, which are not shown, of the flexible circuit matches the required interconnections of the components of the circuit, for example a control circuit for a gear box. The flexible circuit is provided at the edge with at least one connector for connecting an electrical component, for example a control relay. The connector comprises two contact strips 5 which have contact surfaces 6 and 7 respectively which are electrically connected to the respective conductors 2 and 3. For these connections and the mechanical connection of the flexible circuit and contact strips, the connector is preferably provided with a connecting strip 4 which extends from the edge of the flexible circuit 1 virtually perpendicular thereto. Said strip is preferably composed of the same insulating base material as that of the flexible circuit. Two flexible contact strips 5 made of a flexible and electrically insulating material are formed onto the free end of said connecting strip 4. The contact strips 5 are virtually perpendicular to the connecting strip 4 and extend parallel to the edge of the flexible circuit 1. The contact strips 5 extending on either side of the connecting strip 4 are provided on the same side with contact surfaces 6 and 7 which are separated from each other but are connected to the conductors 2 and 3 respectively of the flexible circuit. The connection 8 between the contact surface 6 and the conductor 3 is on the same side as the contact surface 6 and the conductor 3. The connection between the conductor 2 and the contact surface 7 comprises two parts 9 and 10, the part 9 being on the same side as the conductor 2, while the part 10 is on the same side as the contact surface 7. The connection between the two parts 9 add 10 is achieved by the plated-through hole 20. Projecting parts 13 to 14 inclusive are formed onto the free end of each contact strip 5. The free ends of the contact strips 5 are bent over a positioning block 15 until they lie in grooves 16 and 17. The positioning block is provided with holes 18 and 19 into which the connecting pins 21 and 22 can be inserted. The grooves have a depth which is greater than the minimum distance between the side face of the positioning block and the wall of a hole. As a result, an inserted connected pin 21, 22 will be exposed at the position of the associated groove 16 or 17 respectively and the contact surfaces 6 and 7 at the end of the contact strips 5 can come into contact with the connecting pins 21 or 22 respectively, associated therewith, of the control relay 25. The same applies to the other end of the strip 5 and the connecting pin 22. In this way, there is therefore a connection between the connecting pins 21 and 22 and the conductors 3 and 2 respectively of the flexible circuit 1. The grooves 16 and 17 preferably do not extend to the face 23 of the positioning block 15, with the result that the connecting pins are satisfactorily retained and fixed at the beginning of the holes. The protecting parts 11 to 14 inclusive are pressed, after bending over, into respective recesses, of which only the recess 24 can be seen in Figure 2c. A spring clamp which holds the strips 5 in place in the grooves and ensures good contact pressure of the contact surfaces 6 and 7 of the strips 5 against the contact pins 21 and 22 respectively associated therewith is pressed over the contact strips 5 bent over the positioning block 15. The holding of the ends of the strips 5 in place is further improved by the engagement of the projecting parts 11 to 14 inclusive in the recesses 24 associated therewith. The positioning block 15 is provided with a short cylindrical pin 28 which fits into the hole 29 in the connecting strip 4. As a result, the flexible circuit and the positioning block 15 are additionally fixed with respect to each other. The positioning block 15 is further also provided with projecting parts 30 to 33 inclusive between which two recesses are formed for fixing grooves for possibly fixing the positioning block on a guide bracket for the flexible foil. The contact strips 5 are pressed towards each other by a clamping spring 34 in the grooves 16 and 17 of the positioning block. The clamping spring is composed of two resilient legs 35 and 36 which hold the contact strips 5 in place and press the contact surfaces thereof against the inserted connecting pins 21 and 22 of the control relay. The legs are bent in a manner such that the spacing of the free ends of the legs 35 and 36 in the disengaged state is less than the distance between the bottoms of the grooves 16 and 17, while the distance between the legs becomes larger starting from the free ends. As a result, the spring clamp can easily be fitted, while a good contact pressure is ensured. The spring clamp is provided with a strip 37 in which a hole 38 is provided for receiving the pin 28 of the positioning block 15. The spring clamp 34 is provided with a hook-shaped element 39 which engages in a recess 40 of the positioning block 15. It is evident that, as a result of the interaction between pin 28 and hole 38 and the snapping engagement of the hook 39 in the edge of the recess 40, an optimum fixing of the spring clamp is achieved resulting in an optimum holding in place of the contact strips 5 and the connecting strip 4 with respect to the positioning block. In the other embodiment according to Figures 4-6, the pin 28 is centered by means of a cover 44 which is pushed over the positioning block 15. This cover has projecting parts 40-43 for fixing to the guide bracket.

Claims: Flexible circuit provided with at least one connector for connecting an electrical component to corresponding conductors of the flexible circuit, characterized in that the connector is formed by two contact strips (5) made of insulating flexible material which are attached to the flexible circuit and which extend essentially parallel to each other and orthogonally to the flexible circuit in the assembled condition and have, on the surfaces facing each other, contact surfaces (6, 7) which are electrically connected to the corresponding conductors (2, 3) of the flexible circuit, and by a positioning block (15) which is made of insulating material and is provided with holes (18, 19) into which the connecting pins (21, 22) of the electrical components can be inserted, in that grooves (16, 17) in which the contact strips (5) lie are provided in the side faces, adjacent to the holes (18, 19), of the positioning block (15), which grooves (16, 17) have a depth which is greater than the minimum distance between the wall of a hole (18, 19) and the adjacent side face of the positioning block (15), and in that a clamping spring (34) which presses the contact strips (5) towards each other is provided. Flexible circuit according to Claim 1, characterized in that the contact strips (5) extend parallel to, and at a distance from, an edge of the flexible circuit and are connected thereto by a connecting strip (4) on which connecting conductors (8, 9, 10) are provided which are electrically connected, on one hand, to the contact surfaces (6, 7) of the contact strips (5) and, on the other hand, to the corresponding conductors (2, 3) of the flexible circuit. Flexible circuit according to Claim 1 or 2, characterized in that the clamping spring (34) is composed of a strip (37) which is in contact with, and extends in the same direction as, the connecting strip (4) of the flexible circuit and of two resilient legs (35, 36) formed onto either side of the strip (37) which extend transversely to the plane of the strip (37) and in the direction of the grooves (16, 17) of the positioning block (15). Flexible circuit according to Claim 3, characterized in that the strip (37) of the clamping spring (34) is provided, at the end which is furthest from the flexible circuit, with a hook-shaped element (39) which engages in a recess in the face of the positioning block (15) which faces away from the flexible circuit. Flexible circuit according to one of the Claims 3-4, characterized in that the strip (37) of the clamping spring (34) is provided, at the end which is nearest to the flexible circuit, with a hole (38) for receiving a projecting part (28) of the positioning block (15). Flexible circuit according to one of the Claims 3-5, characterized in that the spacing of the legs (35, 36) of the clamping spring (34) at the free end in the disengaged state is less than the distance between the bottoms of the grooves (16, 17) of the positioning block (15). Flexible circuit according to one of the Claims 3-6, characterized in that the spacing of the legs (35, 36) of the clamping spring (34) near the strip is greater than the distance between the bottoms of the grooves (16, 17) of the positioning block (15). Flexible circuit according to any one of the preceding claims, characterized in that the contact strips (5) are provided at the free ends with transversely extending projecting parts (11, 12, 13, 14) which are received in corresponding recesses in the positioning block (15). Flexible circuit according to one of the preceding claims, characterized in that the dimension of the positioning block (15) is greater in the direction of the groove (16) than the length of the groove (16). Connector for a flexible circuit according to any one of the preceding claims, the said connector being as defined in any of the preceding claims, including the positioning block (15) and spring clamp (34) according to any of the preceding claims.

Inventors: MOUISSIE BOB, MOUISSIE, BOB
Applicants: DU PONT, DU PONT NEDERLAND, DU PONT DE NEMOURS (NEDERLAND) B.V., E.I. DU PONT DE NEMOURS AND COMPANY
Application year: 1989
Main classification: H01R9
IPC codes: H01R24, H01R4, H01R12, H05K3, B60R16