JPH053718B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a contact element for a card edge connector having a cantilevered beam and having a contact surface at its free end for engaging conductive traces on a circuit board.

BACKGROUND OF THE INVENTION Card edge connectors typically have contact elements having pins or leads that pass downwardly through the connector and are inserted into a printed circuit board, and a cantilevered beam that extends upwardly along a card-receiving slot.
including. A convex contact surface is located inwardly of the free end of the beam to engage the conductive traces of the printed circuit card. This convex curved surface presents a relatively large metal-to-metal bonding area to provide good wiping action and good electrical contact with the card as the beam engages the card.
U.S. Patent No. 3665370, No. 3671917, No. 4077688
No. 4,303,294 disclose contact elements having the above-mentioned convex curved contact surface, although the overall structure of the cantilever beam is different.

SUMMARY OF THE INVENTION The present invention provides a contact element of the type described above which travels with minimal resistance through oxides and debris on conductive traces of circuit cards and which facilitates this process. Moreover, it has a contact surface that can be wiped reliably and is different from those of the prior art both in concept and structure.

That is, the contact element for a card edge connector of the present invention has a cantilevered beam and has a contact surface at its free end that engages a conductive trace on a circuit board. The tip included in the end is bent at an acute angle with respect to the surface of the circuit board, and the free end is formed with a substantially spherical surface whose center is substantially normal to the surface of the circuit board. When wiping over conductive traces, debris and oxides can be removed more easily and reliably than in the past. Also, the beam can be made shorter by reducing its length.

Embodiments Hereinafter, embodiments shown in the drawings will be described in order to further clarify the present invention.

The ZIF type card edge connector 10 shown in FIGS. 1 and 2 includes a lower housing 12, a contact element 1
4. It includes a pair of cam members 16 movably inserted into the groove 18 of the lower housing 12 and an upper housing 20. lever means (not shown) cooperating between the slot 22 of the projection 24 and the hole 26 of the cam member 16;
moves the members longitudinally. The cams 28 in the groove cooperate with ramps 30 on the cam member to vertically move the longitudinally moving cam member. The upper housing 20 rests on a cam member and is raised or lowered as the cam member is pulled out or pushed in by lever means.

Referring to FIG. 2, the top of contact element 14 is a cantilevered beam designated 32. Referring to FIG. The free end of the beam has a contact surface 34. A convex cam surface 36 is provided inwardly of this free end.

The lower part of the contact element is a lead 38 which is inserted into a through-plated hole in a printed circuit board (not shown).
Retaining means 40 between and connecting the lead and the cantilever beam retain this contact element within the lower housing.

As shown in FIG.
Located on each side of 2. These beams are preloaded so that their cam surfaces 36 rest against the inner wall of the housing. The inner wall also includes an inclined section 44 and vertical sections 46 and 48 above and below it. When the upper housing assumes a lower position (not shown), the cantilevered beam rests on the vertical wall 46 and the contact surface 34 of the free end of the beam is retracted from the card receiving slot 42. The card 50 can now be freely inserted into the slot and withdrawn without being interfered with by the contact surface 34.

As the cam member 16 is pulled along the groove 18, the cam member 16 moves vertically upwardly, causing the upper housing 20 to move in the same direction, causing the sloping wall portion 44 to engage the cam surface 36 of the cantilever beam, causing the beam The contact surface 34 is forced inwardly. The contact surface 34 enters the card receiving slot 42 and contacts the conductive traces of a card 50 (circuit board) inserted therein. The beam is also forced inwardly and extends upwardly to cause the contact surface to slide upwardly along the traces of the card to wipe away any debris, dirt, or other contaminants present. Also, due to the cam 28 and ramp 30, reverse wiping occurs and the trace is also wiped downward. The size of the wipe is approximately indicated by the distance between the two marks 52.

The contact surface 34 is spherical, as shown enlarged in FIGS. 3-6, and is located at the free end of the cantilever beam 32 as described above. Preferably, the spherical surface has a radius of 0.305 mm (0.012 inch). FIG. 4, FIG. 5, and FIG. 6 are drawings showing the spherical shape from different angles.

FIG. 7 is an enlarged view showing the angle of contact surface 34 when engaging conductive traces 54 on card 50. FIG.

As is clear from this figure, the spherical surface of the contact surface 34 has its center substantially normal to the surface of the card 50.

Advantages of the Invention The most important of several advantages of the present invention is that the contact surface can rest against and wipe the conductive trace surface. This "point" type contact surface typically has an engagement radius of approximately 0.635 to 1.016 mm (approximately 0.025 mm).
Tests have demonstrated that it cuts through and clears debris more reliably than conventional contact surfaces of ~0.040 inch). This technical effect is due to the cantilever beam 32
Since the contact surface 34 at the tip of the blade forms a substantially spherical surface and the portion that contacts the conductive trace is a point, debris can be smoothly cut through with minimal resistance while maintaining reliable contact. Also, since the cantilever beam 32 contacts the surface of the circuit board at an acute angle, the contact surface 34 at the tip has sufficient elasticity to contact the conductive trace, and the radius of the contact surface 34 is small enough to contact the trace. High pressure concentration ensures reliable electrical contact.

Another advantage I found was that
Only a small area needs to be plated with a precious metal, such as gold, and substantial cost savings can be achieved.

The contact surface 34 is preferably formed by coining.

As described above, the tip portion including the free end of the contact element for the card edge connector of the present invention is bent at an acute angle with respect to the surface of the circuit board, and the free end has its center substantially normal to the surface of the circuit board. The configuration is such that a certain approximately spherical surface is formed. The effect is therefore summarized as the cantilever beam contacts the surface of the circuit board at an acute angle, and the area where the contact surface 34 contacts the conductive traces is "point" shaped, resulting in less pressure concentration. This height, together with the fact that this contact surface 34 is at the tip of the cantilever beam, provides a sufficient wiping action and also allows for a reverse wiping action. Since the cantilever beams are in contact at an acute angle, the wiping effect when the cantilever beams are pressed into contact is significant, and is particularly suitable for zero insertion force type connectors. Very little precious metal is required to plate the contact surfaces, resulting in cost savings.
Furthermore, since there is no need to curve the tip of the free end to form a contact surface, the height of the cantilever beam can be reduced without impairing the springiness or preloading ability of the beam, making it suitable for small connectors.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a ZIF CardEdge connector incorporating a contact element for a CardEdge connector of the present invention, and FIG. 2 shows a contact element for a CardEdge connector of the present invention engaged with a printed circuit card. 3 is an enlarged perspective view of the contact surface of the contact element for the card edge connector of the present invention, and FIG. 4 is a cross-sectional view of the contact surface taken along line 4-4 in FIG. A cross-sectional side view, FIG. 5 is an end view of the contact surface taken along line 5-5 in FIG. 3,
6 is a cross-sectional view taken along line 6--6 of FIG. 3, and FIG. 7 is a cross-sectional view of the contact surface engaging the conductive traces of the printed circuit card. 14... Contact element, 32... Cantilever beam, 34
... contact surface, 50 ... circuit board, 54 ... conductive trace.

Claims (1)

[Scope of Claims] 1. A contact element for a card edge connector having a cantilevered beam and having a contact surface at its free end for engaging a conductive trace on a circuit board, comprising: a tip portion included at the free end of the contact element; is bent at an acute angle with respect to the surface of the circuit board, and the free end is formed with a substantially spherical surface whose center is substantially normal to the surface of the circuit board. contact element.