Zero insertion force connector for cable to board applications

Abstract: In electrical connector (2) is shown having an insulative housing (4) with a plurality of terminal receiving passages (24), the passageways extending from a lower surface (34) to a position proximate to an upper face (16). A plurality of electrical terminals (70) are disposed within the passageways (24) where posts (86) extend from the lower face (34) for contacting printed circuit board traces. The upper face (16) of the housing (4) includes a plurality of conductor receiving passageways (20) which are in alignment with conductor receiving sections (78), (82) of the electrical terminals (70). An actuator member (50) is moveable relative to the housing and relative to the upper face (16), the movement of the actuator member (50) opening the cable receiving sections (78), (82) of the electrical terminals (70), while release of the actuator member (50) causes the conductor receiving section (78), (82) to engage the exposed conductor of the multiconductor cable for electrical connection thereto.

Description: This invention relates to an electrical connector for interconnecting conductors of a multi-conductor cable to a printed circuit board according to the pre-characterizing part of claim 1. A connector of this kind is known from Molex catalogue concerning 5494 series connectors. Electrical connectors exist in the electronics industry having the capability of interconnecting individual conductors of a multi-conductor flat cable to circuit traces of printed circuit boards. These connectors are mounted to the board having electrical terminals exposed at a lower edge thereof which make electrical contact with the traces on the printed circuit board. The electrical connectors also have electrical terminals which accept the conductors in an electrically conductinq manner. The above prior art electrical connector includes an electrical terminal housing having through passageways for electrical terminals. The housing has a lower face which mounts proximate to the printed circuit board and an upper face which accepts the multi-conductor cable. The terminals are placed in respective passageways within the connector housing, with printed circuit board posts extending beyond the lower face, and cable receiving portions of the terminals disposed proximate to the upper face. The housing also includes a camming member which is moveable to open the cable receiving portion of the terminal, to accept the wire in a zero insertion force fashion. Release of the camming member returns the spring to an undeflected position and into contact with the wire. A disadvantage of the above mentioned connector is that the upper face, which includes the conductor receiving openings, is an integral part of the moveable camming member. Thus, to make the electrical connection, the cable is stripped to expose the conductors, and the cam is actuated to open the conductor receiving portions of the terminals. The actuation of the camming member also moves the upper face and the conductor receiving openings, as the conductor receiving openings are integral with the camming member. When the conductors are inserted within the openings, and the camming member released, the spring force actually forces the camming member, including the upper face and openings, upwardly which drives the cable and conductors upwardly also. This reverse spring force could take the conductors out of contact with the terminals when the upper face is moved. US-A-4 691 975 discloses an IC tester socket having one conductor receiving opening surrounded by a portion of camming member. The camming member has slanted camming surfaces co-operating with slanted portions of conductor receiving portions received in the housing of the tester. Each conductor receiving portion comprises a fixed contact section and a moveable contact section. The moveable contact section can be moved away from the fixed contact section by pushing the camming member into the housing such that said camming surfaces engage with said slanted portions formed on said moveable contacts portions. DE-A-27 07 122 discloses a connector in which the housing includes interior camming members which are actuated by means of an exterior actuation member. This structure requires lots of different parts which are expensive to produce and assemble. The object of the present invention is to provide for an electrical connector of the above mentioned type in which the multiple conductor cable wires can easily be guided and held between the conductor receiving portions. This is achieved by the features of claim 1. The upper face of the housing has a plurality of conductor receiving openings therein, the upper face of the housing and the openings being fixedly rigid relative to the camming member. The camming member is moveable relative to the housing and the upper face, whereby, when the camming member is moved to actuate and release the conductor receiving portions of the terminals, the upper face remains fixed relative to the camming member. According to the instant invention, the electrical connector can accommodate a range of wire sizes. The connector has an insulating housing retaining a plurality of electrical terminals with terminal passageways of the housing, the connector housing having conductor receiving openings therein which are in alignment with conductor receiving sections of the terminals. The conductor receiving openings comprise axially extending passageways comprising arcuate sections contiguous with further surfaces which extend inwardly of the radius of curvature of the arcuate sections, whereby the conductors are aligned towards the center of the passageway by the further surfaces. The preferred embodiment of the electrical connector will now be described with relation to the drawings, where: Figure 1 is a front plan view of the connector of the subject invention; Figure 2 is a top plan view of the connector shown in Figure 1; Figure 3 is a cross-sectional view through lines 3-3 of Figure 2; Figure 4 is a side plan view of the electrical terminal shown in Figure 3; Figure 5 is similar to the cross-sectional view of Figure 3, absent the electrical terminal; Figure 6 is an end view of the electrical connector; Figure 7 is a cross-sectional view through lines 7-7 of Figure 3 showing a large diameter wire terminated; and Figure 8 is a cross-sectional view similar to that of Figure 6 showing an optional smaller diameter wire terminated to the same electrical connector. Figure 9 is a cross-sectional view showing an alternate embodiment of the present invention. With reference first to Figure 1, the electrical connector of the instant invention is designed for applications where the electrical connector is mounted to through holes in a printed circuit board for electrical connection with a plurality of circuit traces on a printed circuit board. The electrical connector provides easy installation of a multi-conductor flat cable by stripping an end of the insulation which covers the conductors of the cable, and the stripped ends of the cable can be inserted into the wire receiving openings of the electrical connector. The subject connector shown generally as 2 in Figure 1 includes an insulating housing 4 having side walls 6 and 8 (Figure 3) and end walls 10 and 12. The electrical connector 2 further comprises an actuator 50 (Figure 2) which is moveable in a downward direction to open the electrical contacts for insertion of the cable conductors. The electrical connector 2 further includes a plurality of electrical terminals 70 (Figure 3) having portions which extend below the lower surface 34 of connector for interconnection with printed circuit boards. With reference first to Figure 5, the housing 4 will be described in greater detail. Figure 5 is a cross-sectional view through lines 3-3 of Figure 2 excluding the electrical terminal 70. The housing 4 includes a plurality of wire receiving openings 20 which extend from the upper wire receiving face 16 and extend into the terminal receiving cavities 24. Also shown in Figure 5 is the fact that the conductor receiving opening 20 merges with a conductor aligning channel 22. With reference now to Figure 7, the detail of the terminal receiving cavity 24 and the wire aligning channel 22 are described in greater detail, remembering that Figure 7 is a cross-sectional view through lines 7-7 of Figure 3. The terminal receiving channel is defined generally by opposed surfaces 24a and 24b while the wire receiving passage is defined by arcs 22b and planar surfaces 22a. It should be noted that the planar surfaces 22a are inside of the radius of curvature which is formed by the arcuate surfaces 22b. With reference now to Figure 4, the electrical terminal includes a horizontal base section 72 which is continuous with a vertical base section 74. Extending from the vertical base portion 74 is a first leg 76 which forms an upper contact portion 78. The leg portion 76 is continuous, through a bight section 77, with a second leg section 80 which extends upwardly to form an opposed and second contact portion 82. Extending from the second leg portion 80 is a lever section 84. Extending from the horizontal base section 72 is a printed circuit board post 86. Finally, with reference to Figures 5 and 6, the actuator includes a horizontal section 52 and arm sections 62 which extend downwardly from the horizontal section 52. An aperture 58 extends from the upper surface 52 of the actuator and extends downwardly to form a stop surface 64 (Figure 6). With reference to Figure 1, the housing end surfaces 10 and 12 each include a recessed section 36 having a downwardly facing latch 38 along a vertical centerline of the recessed section 36. The latches 64 and 38 cooperate to form an upper stop position of the actuator member 50. The lower surface 54 of the actuator in combination with the upper edge 32 of the housing (Figure 5) provide a maximum deflection for the contacts which prevents overstressing the contacts. To assemble the connector of the instant invention, the plurality of terminals are positioned within the housing 4 being inserted through the terminal receiving cavities 24 from the lower surface to the connector housing. The actuator 50 can then be assembled to the connector housing with the arms 62 being inserted into the recesses 36 on each end wall 10 and 12 until the stop surface 64 rides up over the latch to abut the downwardly facing shoulder of the ramp 38. It should be noted that when in this position, the cam surface 56 (Figure 5) is proximate to the lever portion 84 (Figure 3) such that downward movement of the actuator 50 causes an outward deflection of the lever portion 84 on the cam surface 56, thereby spreading the opposed contact portions 78 and 82 for insertion of the stripped conductors. It should be noted that the actuator 50 moves relative to the housing and relative to the wire receiving openings 20. Said differently, the wire receiving openings are not integrated with the actuator such that the wire receiving openings move upwardly and downwardly with the actuator. In some prior art connectors, the wire receiving openings are integrated with the actuator and when the actuator is deflected downwardly and the cable is inserted into the wire receiving openings, the release of the actuator tends to push the cable back out of contact with the electrical contacts. The present invention has also been designed to accommodate a range of wire sizes, the wire receiving channels 22 are profiled to receive and align conductors of various diameters, as shown in Figures 7 and 8. This has been accomplished by providing a wire receiving channel 22 extending vertically within the side walls 24a, 24b of the terminal receiving cavity 22 as shown in Figures 5 and 7. The wire receiving channel 22 first includes radiused sections 22b which are continuous with planar surfaces 22a. As shown in Figure 7, the worst condition of termination is shown where the electrical terminal 70 is right justified within the terminal receiving cavity 24 whereas the conductor C₁ is left justified within the conductor receiving channel 22. However, the planar surface 22a positions the conductor by providing a tangent surface to the conductor C₁ to prevent the conductor C₁ from moving further to the left. Furthermore, the planar surfaces 22a provide tangent surfaces which are within the radius of curvature of the path formed by arcs 22b. As shown in Figure 7, even with the worst case condition, the electrical terminal continues to have an overlap from the edge of the terminal to the center of the conductor, of a distance L₁. Since there is an offset L₁, the conductor C₁ is mainly gripped between the two opposed contacts 82, 78; rather than relying on the plastic of the housing for a contact force. The planar surfaces 22a are only used for alignment. As shown in Figure 8, a small conductor C₂ having a diameter D₂ can also be terminated within the connector again with the surface 22a positioning the conductor within the wire receiving channel 22 with the overlap of the edge of the terminal and the center of the conductor of a distance L₂. Other advantages of the above mentioned design should be readily apparent. For example, this electrical connector can terminate electrical conductors having diameters which are larger than the thickness of the electrical terminals (t), which allows for a very dense connection system on very close centerlines. Also, since the contacts are edge stamped, as opposed to stamped and formed, the contacts can also be placed on very close centerlines. Since the contacts are edge stamped, the normal force is much higher than a comparably sized stamped and formed terminal. Another advantage of this design of electrical connector is that the conductor receiving openings can be alternately formed as shown in Figure 9 such that every other opening is a mirror of the previous one. This places adjacent planar surfaces 22a in a parallel manner which allows for a thin web of material to interconnect the two adjacent openings thereby allowing for very close side-by-side spacing.

Claims: An electrical connector (2) for interconnecting conductors (C) of a multi-conductor cable to a printed circuit board comprising an electrical terminal housing (4) and a plurality of electrical terminals (70); the housing (4) having through passageways (24) for the electrical terminals (70), and a lower face (34) which mounts proximate to the printed circuit board and an upper face (16) which accepts the multi-conductor cable; the terminals (70) being placed in respective passageways (24) within the connector housing (4), with printed circuit board posts (86) extending beyond the lower face (34), and conductor receiving portions (78, 82) of the terminals (70) disposed proximate to the upper face (16); the housing (4) also including a camming member (50) which is moveable relative to the housing (4) to open the conductor receiving portions (78, 82) of the terminals (70), the electrical connector (2) being characterized in that: the upper face (16) of the housing (4) is rigidly fixed relative to the camming member (50), and has a plurality of discrete conductor receiving openings (20) formed within the periphery of the upper face (16) of the fixed housing (4), the conductor receiving openings (20) being in communication with the conductor receiving portions (78, 82) of the terminals (70), the camming member (50) being spaced from the openings (20) and moveable relative to the housing (4) and the upper face (16) to actuate and release the conductor receiving portions (78, 82) of the terminals (70), the conductor receiving portions (78, 82) comprising a moveable contact section (82) to which is attached a moveable arm (80) having at its upper portion a lever section (84) extending therefrom which is disposed proximate to the upper face (16) and directly actuable by the camming member (50), the conductor receiving portions (78, 82) being attached to a common spring section (76, 77, 78) extending therebetween for resilient biasing of the conductor receiving portions (78, 82) against the multi-conductor cable. The electrical connector of claim 1, characterized in that the terminals (70) are edge stamped from a strip of metal. The electrical connector of claim 2, characterized in that the terminals (70) comprise opposed contact sections (78, 82) defined by sheared edges of the contact, the opposed contact sections (78, 82) being aligned with the discrete conductor receiving openings (20). The electrical connector (2) of claim 3, characterized in that one of the opposed contact sections is a fixed contact section (78) and the other of the opposed contact sections is the moveable contact section (82). The electrical connector of any preceding claim characterized in that the terminal (70) comprises a vertical base section (74) attached at its upper end to the housing, and extending at its lower end into a horizontal base section (72) to which is attached a printed circuit board post (86) for mounting to the printed circuit board, whereby the common spring section (76, 77, 78) is attached to the vertical base section (74) proximate its upper end. The electrical connector (2) of any of claims 1-5 characterized in that each terminal passageway (24) comprises a channel (24a) to receive the individual moveable arms (80), the channels (24a) having an upper surface (27) which is lower than the lever sections (84), which disposes the lever sections (84) into an open channel (25) in the housing (4). The electrical connector of claim 6 characterized in that the camming member (50) is disposed within the open channel (25), each lever section (84) having a dedicated camming surface (56) in contact therewith, the individual camming surfaces (56) being separated by a plurality of side-by-side walls (30) to isolate the lever section (84). The electrical connector of any preceding claim characterized in that the conductor receiving openings (20) comprise axially extending passageways comprising arcuate sections (22b) contiguous with further surfaces (22a) which extend inwardly of the radius of curvature of the arcuate sections (22b), whereby the conductors (C) are aligned towards the center of the passageway by the further surfaces (22a). The electrical connector (2) of claim 8, characterized in that the further surfaces (22a) are defined by planar surfaces (22a).

Inventors: SOES LUCAS, SOES, LUCAS
Applicants: WHITAKER CORP, THE WHITAKER CORPORATION
Application year: 1990
Main classification: H01R9
IPC codes: H01R12, H01R24