WO2008050184A1

WO2008050184A1 - Zero insertion force connector for a flexible connection member

Info

Publication number: WO2008050184A1
Application number: PCT/IB2006/054690
Authority: WO
Inventors: Michel Fonteneau
Original assignee: Fci
Priority date: 2006-10-24
Filing date: 2006-10-24
Publication date: 2008-05-02

Abstract

A connector (1) for receiving a flexible connection member (2) having a set of conductive tracks, said connector comprising a set of conductive contact elements (11) corresponding to the set of conductive tracks, and located on a connection surface (3), a pressure device (5) being moveable between a first position and a second position, said pressure device being arranged in said first position to resiliently exert a force on the flexible connection member in direction of said conductive contact elements, in the second position to release the flexible member, wherein the conductive contact elements are rigidly fixed on the connection surface.

Description

ZERO INSERTION FORCE CONNECTOR FOR A FLEXIBLE CONNECTION

MEMBER

The present invention relates to a zero insertion force electrical connector, which provides electrical connection between a flexible connection member such as a flexible printed circuit (FPC) or a flat cable with a circuit substrate, such as a printed circuit board (PCB) .

A zero insertion force connector for receiving a flexible connection member is known from US patent 6,280,217. Fig 1 illustrates such a prior art connector 101 which comprises a housing 104 adapted to receive a flexible connection member 102 having on a surface a set of conductive tracks (not shown on Fig. 1) . For each track, a corresponding movable contact element 103 is mounted into channels provided to the housing 104. The shown contact element 103 comprises a resilient contact arm 105, attached to a base member 106 received into corresponding channel. An actuator 108 is pivotably mounted on the housing 104 and is moveable between two positions, i.e. an opened position (not shown), in which the flexible connection member may be inserted into the housing 104 without exerting an insertion force, and a closed position, as shown in Fig. 1.

In use, the end of the flexible connection member is inserted into the front opening of the housing so as to be located between the actuator 108 and the contact portion

107 of the contact arm 105 and loosely contacts said contact portion 107. When the actuator is rotated down to a horizontal position (the closed position) , a pressing surface 109 of the actuator 108 presses the flexible connection member 102 onto the contact portion 107 of the contact arm 105 so that said flexible connection member is maintained in position and electrically connected with the connector to corresponding conductive track of a printed circuit board.

However the prior art connector presents the drawback that it can only be suitably used with flexible member whose distance between successive conductive tracks is not too small. As a matter of fact, with the prior art connector the contact elements need to be thick enough to exert a sufficient force on the flexible connection member and to be spaced apart from a minimum distance (pitch) to avoid short circuit issues. Moreover, it is necessary that the contact elements be positioned very accurately relative to the tracks in order to avoid problems of contact resistance or problems of wear on the contact elements and on the flexible member.

To provide a closely packed high-density connector, it is necessary that the connector includes low pitch contacts. However this required feature is not easy to achieve insofar as high tolerances between the dimensions of the channels and the contact elements are added and have to be met during the manufacturing process.

In addition, to make the prior art connector, a large number of pieces need to be assembled, and these pieces are all very small, making them difficult to manufacture and thereby increase the manufacturing costs.

In light of foregoing, it is an object of the invention to provide a high-density connector that overcomes at least one of the above-mentioned drawbacks.

To this end, the invention proposes a connector according to claim 1. Thus, by having the contact element rigidly fixed to a connection surface of the housing, a stable positioning of the contacts is guaranteed. In addition, given that the contact element is fixed with respect to the housing surface, tolerance requirement between the channel and the associated contact element are eliminated. This allows providing a connector having conductive tracks with smaller pitch where tolerance issues are minimized. Thus, due to the reduction of the pith between adjacent contact elements, it is now possible to provide a connector, of a given size, capable to connect flexible connection members with higher track density.

Finally, the connector according to the invention comprises a reduced number of individual elements and thereby its assembly is easier.

Furthermore, the connection surface may be easily realized with known method such as MID, or photo and etching etc.

Other features advantages of this invention, corresponding to one or several depending claims, will further appear in the description when considered in connection to the accompanying drawings, wherein:

Figure 1, already described, is a sectional view of a state of the art zero insertion force connector; - Figures 2a and 2b are cross sectional views of a first embodiment of the invention respectively in an opened state and in a closed state; and

Figures 3a and 3b are cross sectional views of a second embodiment of the invention respectively in an opened state and in a closed state. Certain terminology may be used in the following description for convenience only and is not considered to be limiting. For example, the words "upper", "lower" designate directions in the drawings to which reference is made .

As depicted on Figures 2a and 2b, a connector 1 according to the invention is adapted for receiving a flex connection member 2. The flexible connection member comprises a set of tracks disposed on its lower surface. The connector 1 comprises a housing including a flexible member insertion slot and having a base portion 4' providing a connection surface 3 on which are disposed a set of conductive contact elements 11. These contact elements 11 are rigidly fixed on the connection surface. The connector is placed on a printed circuit board

(PCB) (not shown) . In order to establish electrical transmission between the tracks of the flexible member and the conductive paths of the PCB, the lower surface of the base portion 4' is provided with conductive means, electrically connected to the contact elements 11, and further facing a corresponding conductive path of the PCB.

Advantageously the thickness of the base portion 4' of the housing 4 can be reduced as much as possible so as to minimize electrical resistance between the contact elements 11 and the PCB conductive paths. An effect is that a high-speed FPC/FFC connector may be manufactured.

According to the invention, these contact elements 11 may be printed on the connection surface. However, it is possible to obtain these contact elements 11 with etching method (for instance photo and etching) or by an MID process on the connection surface. It is also possible to laminate these conductive contact elements 11 on the connection surface. These methods permit to easily form the connection surface 3. Moreover, a lower pitch is allowed by such methods, when compared with state of the art connector. Consequently, it permits to reduce the size of the connectors by lowering the pitch of the contact elements on the connection surface and/or increasing the number of connections.

This connector further comprises a pressure device 5 including a resilient finger 6 and a base 7 attached to the housing 4. The resilient finger 6 can be manipulated by an actuating arm 8 actuating the surface of a cam 9. This actuating arm is pivotably mounted on the housing 4. As illustrated on Figure 2a, when the actuating arm 8 is in the open state, the cam 9 maintains the resilient finger 6 away from the connection surface 3. Thus, the flexible connection member 2 may be inserted without effort.

Once a flexible connection member 2 is inserted in said connector 1 through the slot, the actuating arm 8 is brought in closed state, as illustrated on Figure 2b, wherein the cam 9 allows the resilient arm 6 to exert a force on the flexible connection member 2 substantially normal to the connection surface 3. Thus, the force applied on the flexible member permits to ensure physical contact between the tracks of the flexible connection member and the corresponding contact elements 11 disposed on the connection surface 3.

The connector according to the invention can be used with a flexible connection member provided with conductive tracks disposed on only one side of the connection member, i.e. with one-sided conductive flexible connection member. In use, the pressure device exerts a force on the opposite side of the flexible member. If said opposite side of said connection member is be made of non-conductive material, this allows having a pressure device made of metal. This is advantageous as regards to robustness of the connector and contact force action.

In order to improve the electrical contact between each contact element with its respective track, a plurality of resilient fingers may be provided to the pressure device. For instance, for each contact element

11, an associated resilient finger 6 is provided.

These resilient fingers may be realized in plastic or in metal.

If the pressure fingers of the connector according to the invention are in metal and when said connector is used to connect a one-sided conductive flexible connection member, it is not necessary to ensure the insulation between each metallic pressure fingers 6 since the pressure fingers act on a non-conductive surface of said flexible member. The resilient fingers 6 may also be advantageously formed as a comb shaped element. Such a comb shaped member comprises a plurality of pressure fingers resiliently fixed on a single base. This permits to simplify the number of pieces forming the connector 1, inducing a reduction of time and cost of manufacturing.

However, when these metallic pressure fingers are electrically isolated one from another, they may be used as individual electrical contact elements. They therefore can be implemented in a connector especially adapted to connect double-sided flexible connection members, i.e. connection members comprising conductive tracks located on both lower and upper surfaces. The pressure device connection portion 10 of the pressure device may be used as electrical tail to connect the finger 6 to a corresponding track of a PCB on which the connector is mounted. Another embodiment of the invention is illustrated on Figures 3a and 3b. As in the first embodiment, this connector comprises a connection surface 3 with conductive contact elements disposed rigidly on this connection surface 3. In this embodiment, the connector 1 is provided with an actuating arm 12 having a plurality of pressure portion 13, corresponding to each contact element 11, and adapted to exert a force substantially normal to the connection surface 3. This actuating arm 12 is pivotably mounted on the housing 4, and when closed, is rigidly maintained in position. In the example illustrated, a cam

14 of the actuating arm 12 cooperates with a resilient arm

15 of a spring member 16 attached to the housing 4 by a spring base 17. In order to accurately provide the force to be exerted by the actuating arm 12, the latter may be advantageously realized in metal. However, it is also possible to realize it in plastic. In this case, the pressure portion 13 may be advantageously coated with rubber or other elastic materials, in order to improve the contact between the latch and the flexible connection member 2.

As illustrated on Figure 3b, when the actuating arm 12 is closed, the resilient arm 15 maintains it in position, through the cam 14. The pressure portion 13 exert a force on the upper side of the flexible connection member 2 so that the conductive tracks disposed on the lower surface of the flexible connection member are maintained in contact with the conductive contact elements 11 of the connection surface 3.

As a variant of the embodiment illustrated on Figures 3a and 3b, the actuating arm 12 has a single pressure portion 13, either made in plastic or made in metal . In this latter case, the flexible connection member 2 is provided with conductive tracks on only one side.

In both embodiments, the connection surface may be a flexible substrate allowing to improve the contact between the contact elements 11 and the conductive track of the flexible connection member, maintained by the pressure device 5 or 12.

Claims

1. A connector (1) for receiving a flexible connection member (2) having a set of conductive tracks, said connector comprising: - a housing (4) defining a flexible connection member insertion slot, said housing includes a base portion (4') providing a connection surface (3) and conductive contact elements (11),

- a pressure device (5) movably mounted onto the housing (4) between a first position where the pressure device (5) exerts a force on the flexible connection member (2) in direction of said conductive contact elements (11), and a second position allowing insertion/de-insertion of the flexible connection member (2) , wherein the conductive contact elements (11) are rigidly fixed on the connection surface (3) .

2. The connector of claim 1, wherein the conductive contact elements (11) are printed on the connection surface (3) .

3. The connector of claim 1, wherein the conductive contact elements (11) are etched on the connection surface (3) .

4. The connector of claim 1, wherein the conductive contact elements (11) are realized by MID on the connection surface (3) .

5. The connector (1) of claim 1, wherein the conductive elements (11) are laminated on the connection surface (3) .

6. The connector (1) of any one of the preceding claims, wherein the pressure device (5) comprises a plurality of pressure fingers (6) resiliently fixed on a base (7) .

7. The connector (1) of claim 6, wherein each pressure finger (6) is associated to one contact element (11) .

8. The connector (1) of claims 6 or 8, wherein the pressure fingers (6) are in metal.

9. The connector (1) of any one of the preceding claims, further comprising an actuating arm (8) adapted to actuate the pressure device (5) .

10. The connector (1) of claim 9, wherein the actuating arm (8) is pivotably moveable between a closed position and an opened position, said arm (8) comprising a cam surface (9) arranged to actuate the pressure device (5) between the first and second positions.

11. The connector (1) of claims 9 or 10, wherein the actuating arm (8,12) comprises a surface with a plurality of pressure portion (13) protruding from said surface.

12. The connector (1) of claim 11, wherein each pressure portion (13) is associated to a contact element (11) .

13. The connector of any one of the preceding claims, wherein the connection surface (3) is flexible.

14. An electrical connector assembly comprising a connector (1) of any one of the preceding claims and a flexible connection member (2) including a first side having a first set of conductive tracks and a second non conductive side, wherein the pressure device (5) exerts a force on said second non conductive side.

15. An electrical connector assembly comprising a connector (1) of any one of claims 8 to 13 and a flexible connection member including a first side having a first set of conductive tracks and a second opposite side having a second set of conductive tracks, wherein the pressure fingers (6) are electrically connected to the second set of conductive tracks.