LOW INSERTION FORCE CONTACT FOR USE IN HIGH DENSITY CONNECTOR SYSTEMS BACKGROUND OF THE INVENTION This invention relates to a low insertion force contact of the type used in high density connector systems. More pa ticularly, the invention is directed to a contact which permits a high pin count while providing relatively low insertion forces due to the high pin count, and still maintaining sufficient contact normal forces to ensure contact integrity when employed on a connector insulator block on a printed circuit board in a surface mount type application.

In the prior art it has been known to use connector insulator blocks mounted, for example, in a surface mount arrangement on a printed circuit board with contacts inserted within "pockets" or "passages", hereinafter "pockets", of the connector insulator block and with the contacts having the tail portions thereof projecting from the pockets and inserted in through- holes of a printed circuit board and being soldered therein to complete an electrical circuit on the printed circuit board. Typically, the contacts are flexible on the other side of the pocket, i.e. the front end so that another printed circuit board can be connected to the printed circuit board holding the connector insulator block to complete a circuit arrangement therewith. The connector or contact portions for the other circuit board will typically employ pins which are inserted into the pockets of the connector insulator block and engage the compliant portions of the contacts located therein to complete the desired circuit.

In arrangements of this type wherein a high density connector system requires a large pin count to effect the mating and un ating, it becomes necessary to accurately determine and predict the individual insertion forces as a function of overall tolerances and position variables which may be encountered in such

large systems. Further, it becomes necessary to provide relatively small dimensioned contacts, which while reduced in size still provide sufficient contact normal forces to ensure contact integrity and electrical continuity. Moreover, the contacts much be such that when inserted in the connector insulator block, low insertion forces are required due to the high pin count in the connector.

In the prior art, typically these objects are achieved by providing a contact which is a single beam type contact, which results in small dimensions, low insertion forces, and due to the flexibility of the contact portion, maintained electrical connection with pins being inserted into the connector insulator block thereof.

An example of a prior art single beam contact is shown in Figure 1 as element 1. It includes a tail section 5 which typically projects out from a connector insulator housing or block, and is soldered into a through-hole of a printed circuit board upon which the connector insulator housing is mounted. The top portion or front portion includes the contact portion 3 which is generally deformed and flexible in nature such that when snuggly received within a pocket in a connector insulator housing, flexes in the direction of arrow B when contacted by a pin from another printed circuit board being connected to the connector insulator housing or block as inserted in the direction of arrow A, i.e. from the front of the connector insulator housing. While generally performing satisfactorily in certain applications, it is often the case that the contact portion 3 will deform excessively and not return to its prior shape or due to vibrations will lose electrical contact and thus, some looseness or play in the contact surfaces occurs resulting in the possibility that the pin 7 may lose electrical continuity with the contact 1.

In order to overcome this problem, the prior art has also developed what is known as a dual tine or dual

contact surface contact 1 as shown in Figures 2a and 2b respectively in side as well as perspective view. in Figures 2a and 2b like elements designate the same elements as in Figure 1 as well as in the remainder of this application.

As shown in Figures 2a and 2b, the contact 1 includes a tail section 5 as well as dual tines 3a and 3b including a constricted portion as generally shown unnumbered, which establishes contact with a pin 7 which is inserted in the direction of arrow A into the connector insulator housing. The constricted portion is of a lesser diameter than that of the pin 7 and thus, is forced outwardly in the direction of the arrows B to establish the electrical contact. Numerous advantages are provided by the dual beam structure. For instance, the dual beam structure provides resistance to intermittent loss of contact due to vibration. It also provides dual contact points as well as increased conductor cross-section for lower bulk resistance. Moreover, normal forces are absorbed by opposing tines instead of the pocket walls and as such, the dual tine contact provides a significant improvement over the prior art single tine.

On the other hand, when using a dual tine contact such as as shown in Figures 2a and 2b, in order to provide a desirable amount of normal force, for example, in the case of high density interconnect systems, typically 50 to 100 grams, preferably 75 grams normal force is desired, a U-shaped contact such as that of Figures 2a and 2b requires an excessive amount of width or a relatively thick tine portion as illustrated by arrows T to develop the required force. The increased width makes such a dual tine contact inoperable for use in high density connector applications.

Further, in the case of the thick tine contact, the contact surfaces themselves must be stamped, which is undesirable since the surfaces include a large number of burrs and roughness. Moreover, in the past such con-

tacts have been held stationary in an insulator at the curved region wherein the arrows T are shown, which can result in tines flexing unevenly depending on the positioning of the mating pin upon entry. Further, in the case of the wide tine contact, the gap between contact points must be small or non-existent due to the greater deflection of the tines necessary to develop the required normal forces. Accordingly, the first contact of the pin 7 with the surfaces of tines 3a and 3b will at a point where the tangent to the surfaces of tines 3a and 3b is at a large angle with respect to the direction of entry of pin 7 as shown by arrow A. Accordingly, the forces required in the direction of arrow A to achieve flexing in the direction of arrow B are, as can be determined by simple triangulation in a conventional manner, are excessively large.

SUMMARY OF THE INVENTION

It is thus and object of the present invention to provide a dual tine contact which can be employed in high density connector systems.

Another object of the present invention is to provide such a dual tine contact which is of narrow dimensions but still maintains the high normal forces desirable in such high density interconnect systems.

These and other objects will become more readily apparent to those of ordinary skill in the art from a reading of the remaining disclosure and claims.

In accordance with one aspect, the invention comprises a low insertion force contact for use in a high density connector system made up of a body having a tail section and dual tine contact portion. The tail section is a generally longitudinally extending plate¬ like section constructed for engaging with a slot in a pocket in a connector insulator for holding the contact in a fixed position in the pocket when inserted into the pocket from the front of the connector insulator housing. A dual tine connect portion is provided comprising two longitudinally and parallel extending

plate-like sections oriented at about 90° about their respective axes with reference to the tail section.

Dual contact surfaces are located at the ends of the two longitudinally extending plate-like sections making up the dual tine contact portions. The dual contact surfaces are plate-like sections oriented about their longitudinal axes at about 90° with reference to the longitudinally extending plate-like sections, and generally in the same plane or a plane parallel to that of the tail section. In another apsect when constructed for being inserted from the rear of a connector insulator, the tail section will include engagement means to engage the walls of a pocket of a connector insulator to prevent the low insertion force contact from being withdrawn therefrom out from the rear section into which it was inserted.

Having briefly discussed the invention, the full details thereof will become more readily apparent from the following detailed discussion of the invention made with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is as previously discussed, a side view of a prior art single tine contact for use in high density connector systems shown with a pin contact being inserted for establishing electrical connection with the contact.

Figures 2a and 2b, as also previously discussed, are respectively, side and perspective views, of a prior art dual tine contact shown with a pin being inserted to establish an electrical connection therewith.

Figures 3a and 3b are perspective and side views, respectively, of one embodiment of the contact in accordance with the invention showing the pin contact from another board about to be inserted for establishing electrical connection therewith.

Figures 4a and 4b are views the same as those of Figures 3a and 3b, respectively, showing an alternative embodiment of the contact in accordance with the

invention .

Figure 5 is a partial view from the front of a connector insulator showing pockets especially constructed for receiving and holding the contacts of Figures 3a and 3b therein. Figure 6 is a schematic side cross-sectional view of the contact of the invention, in accordance with the embodiment which is mounted from the front of the connector insulator housing of Figure 5 shown about to engage with a pin contact being inserted for connection therewith.

DETAILED DISCUSSION OF THE INVENTION

The prior art contacts of Figures l-2b have been previously discussed and will not be discussed further herein. In this regard, it is noted that with reference to the invention, like elements will be used to designate like elements as compared to the above-prior art discussion.

One embodiment of the invention is shown in Figures 3a and 3b, with a similar embodiment being shown in Figures 4a and 4b. In Figures 3a and 3b a contact 1 is shown having a tail section 5 which is a generally longitudinally extending plate-like structure. The tail section is generally oriented perpendicularly, or at a 90° angle, about its axis with respect to the remainder of the contact. The contact 1 also includes dual tine portions 3a and 3b. The dual tine portions 3a and 3b include contact surfaces 9a and 9b which are also generally plate-like in structure and extend longitudinally and oriented within planes substantially parallel to the plane of the tail 5. As shown therein, a pin 7 will then be inserted in a manner for contacting the contact surfaces 9a and 9b.

As will be readily appreciated, the contact 1 in accordance with the invention differences from the prior art dual tine contacts in that to minimize pocket width, the contact is turned on end at its contact dual tines 9a and 9b to take advantage of increased strength of the

beam in the- illustrated orientation of loading. This results in a higher spring rate and a lower stress for given load and thus, the contact normal forces discussed previously can be maintained without a consequent increase in size as is required with conventional prior art dual tine contacts.

Further, this arrangement provides that the contact in accordance with the invention can be formed out of a stamping of a plate-like arrangement with the tail 5 as previously discussed, merely turned about its axis to be perpendicular to the dual contact tines 3a and 3b and within the same plane can form the generally curved plate-like contact surfaces 9a and 9b. Moreover, the specific structure is especially adapted for front end loading into the pockets 23 of the connector insulator housing 21. As shown in Figure 5, the contacts 1 will be inserted from the front in the direction of arrow C with the pockets 23 being especially constructed to receive and hold these contacts securely therein.

More particularly, the pockets 23 include a central portion 27 which receives the tail section and holds it securely. Adjacent slots 25 as defined by walls 25a, as further shown in Figure 6, receive the dual tines 3a and 3b with the contact surfaces 9a and 9b projecting into the center portion 27 in a manner such that when a pin 7 is inserted, surfaces 9a and 9b expand but are prevented from expanding an excessive amount by top wall surfaces 23a of the pocket 23. As will be clearly evident, the pockets 23 are constructed or configured in a manner such as to receive the contacts of the invention which, as clearly shown in the drawings, can be manufactured by first being punched out of a plate-like structure with the forming of the other surfaces, i.e. the tail 5 as well as the contact surfaces 9a being merely formed by bending portion of the punched out plate structure.

In an alternative construction as shown in Figures 4a and 4b, the contact 1 can be punched and formed in a manner such that it includes an engaging means 11, for

example, a flexible tab 11 so that the pockets 23 of the connector insulator housing 21 need not be specially configured and can be of a conventional square like configuration. In this case, the contacts 1 would be inserted from the rear of the connector insulator housing with the tab 11 engaging the walls of the pockets 23 to prevent withdrawal therefrom. In this case a top wall surface would prevent the contact surfaces 9a and 9b from projecting out the front of the pocket -23 but sufficient clearance would be provided within the pocket 23 itself to enable the expansion of said surfaces and corresponding tines 3a and 3b.

In any event, as contrasted to the contact of Figures 2a and 2b, due to the unique construction the gap between contact surfaces 9a and 9b can be enlarged compared to the prior art dual tine contact. This provides for entry contact of the pin 7 at a point on surfaces 9a and 9b is at a relatively small angle with respect to direction of entry and as such the entry force is relatively small, as compared to the prior art, to cause the tines 3a and 3b to flex outward. Moreover, since the contact 1 is held at the tine 5, a space is provided by the pocket dimensions to permit a free floating relationship of the tines 3a and 3b as shown in dashed lines in Figure 6. This permits entry at an angle of pin 7 while resulting still in an equal flexing of both tines 9a and 9b.

With respect to the materials employed in making the contacts, these are typically conductive materials of sufficient strength to withstand the repeated connections and disconnections, i.e., they must be flexible enough to expand upon insertion of a pin 7.

The selection of these materials is conventional and will be readily apparent to those of ordinary skill in the art.

Having thus described the invention, the appended claims define what applicants consider to be the invention but is not intended to be limitative in any way.