Zero insertion force contact for use with a pin grid array

Details Zero insertion force contact for use with a pin grid array Zero insertion force contact for use with a pin grid array

1999-12-02

2002-04-16

Ta, Tho D. (Department: 2833)

Electrical connectors

With coupling movement-actuating means or retaining means in...

Including compound movement of coupling part

C439S071000, C439S266000, C439S259000

Reexamination Certificate

active

06371784

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to connectors in general. More particularly, the invention relates to a contact for use with a socket to receive pins from a pin grid array (PGA).
BACKGROUND OF THE INVENTION
The speed at which computers operate is becoming increasingly faster. At the heart of a computer is a computer processor. The processor is always in a constant state of technical innovation. It seems that everyday new applications are being created that demand a faster and more powerful processor. As the speed of the processor increases, it becomes increasingly important for all the components in the data processing path to become faster in order to prevent data congestion or “bottlenecks.” This includes the interface that connects a processor to a printed circuit board (sometimes referred to as a “mother board”).
One example of such an interface is referred to as a Pin Grid Array (PGA) socket. The PGA socket is designed to receive a pin grid array of a processor and to establish an electrical connection between the processor and the printed circuit board. The PGA socket varies in type in accordance with such design factors as the number of pins in the pin grid array, the type of contacts located in the PGA sockets, the locking mechanism for maintaining a connection between the contacts and the pins of the pin grid array, and so forth.
One often desirable design feature of a PGA socket is a Zero Insertion Force (ZIF) PGA socket. A ZIF PGA socket is a PGA socket that requires little or no force to insert the pins of the pin grid array into the corresponding PGA sockets. Once the pins of the pin grid array are inserted into the corresponding PGA sockets, a mechanism included with the socket is operated to move the pins into registration with the socket contacts and into electrical engagement therewith.
Another desirable feature of a PGA socket is the number of socket contacts offered by the PGA socket. Current processors have pin grid arrays with hundreds of pins. Consequently, the number of socket contacts required by the PGA socket has steadily increased to the point where a 50×50 centerline grid of sockets is necessary. In other words, each socket is approximately 0.050 inches from the sockets around it. A PGA socket having a 50×50 centerline grid of sockets is often referred to as a “micro” PGA socket.
Thus, there is a substantial need in the interface industry for a micro ZIF PGA socket to accommodate the mechanical and electrical requirements of modern day processors. In order to provide a micro ZIF PGA socket, however, the type of contacts used by the socket becomes critically important. The contact performs many functions, not the least of which is to provide electrical contact between the pin and printed circuit board. As each desirable design feature is introduced for a processor and hence the PGA socket, the electrical and mechanical design constraints for the contact become more stringent. For example, as the processing speed of a processor increases, the amount of inductance tolerated from the contact is reduced. Conventional contacts have an inductance value of 5-6 nanohenrys (nh). Modern day processors, however, require an inductance value of no more than 3.7 nh. Moreover, many processors require that the height of the contact remain the same as previous contacts. In addition, the desire for the ZIF feature requires a pin receiving portion that is capable of receiving a pin without providing any resistance, and of being moved into contact with the pin to provide the electrical connection. Furthermore, the overall width of the contact must be such that it fits within a socket designed for a 50×50 centerline grid. Each of these design constraints provide a formidable challenge in the design of the contact to perform as desired.
In view of the foregoing, it can be appreciated that a substantial need exists for a contact that solves the above-discussed problems.
SUMMARY OF THE INVENTION
The embodiments of the invention include a contact to electrically connect at least one pin of a pin grid array to a printed circuit board. The contact comprises a receiving portion having a pair of contact arms, with each contact arm having a curved portion and a straight portion. The contact arms are positioned so that the curved portions form a curved receiving area while the straight portions are substantially parallel to each other to form a contact area. The contact also includes a tail portion having a solder ball receiving portion. The contact further includes a center portion connecting the pin receiving portion to the tail portion.
With these and other advantages and features of the invention that will become hereinafter apparent, the nature of the invention may be more clearly understood by reference to the following detailed description of the invention, the appended claims and to the several drawings attached herein.


REFERENCES:
patent: 4498725 (1985-02-01), Bright et al.
patent: 4934967 (1990-06-01), Marks et al.
patent: 5791929 (1998-08-01), Banakis et al.
patent: 5797774 (1998-08-01), Kaneko
patent: 5984694 (1999-11-01), Sinclair
patent: 6113412 (2000-09-01), Lin
patent: 6142810 (2000-11-01), Hsiao et al.
patent: 6193537 (2001-02-01), Harper, Jr. et al.
patent: 0095877 (1983-05-01), None
patent: 2 775 133 (1999-02-01), None
PCT International Search Report for application No. PCT/US 00/32740.

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