Zero insertion force sockets using negative thermal...

Details Zero insertion force sockets using negative thermal... Zero insertion force sockets using negative thermal...

2000-08-02

2001-07-24

Patel, Tulsidas (Department: 2839)

Electrical connectors

Heat responsive contact pressure control

C174S260000

Reexamination Certificate

active

06264486

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the field of integrated circuits, and, more particularly, to integrated circuit devices having offset junctions to protect circuits from an electrostatic discharge (ESD) and methods for their manufacture.
2. Description of the Related Art
Electrical components are often mounted in sockets comprising spring contacts. These sockets allow easy installation and replacement of electrical elements. With conventional sockets, the terminal pins of an integrated circuit (IC) are pressed into a socket and deflect the spring contacts.
Modern integrated circuits are often complex and may have a large number of pins. While the force required to insert an individual pin into a socket receptacle is modest, simultaneously inserting a large number of pins into their respective sockets can require a significant insertion force. The insertion force can damage the integrated circuit or bend the pins when the force is significant or when the sockets and pins are not properly aligned.
To avoid the problem of damaging the IC or the pins, various kinds of zero insertion force (ZIF) sockets have been developed, whereby the terminal pins of an IC can be inserted into and withdrawn from such sockets with minimal or no insertion and withdrawal force. This facilitates easy change or replacement of the IC, which is often necessary.
A widely used conventional zero insertion force socket substantially includes a socket housing having a plurality of metallic conductive contacts disposed in the insertion holes. The insertion holes of the socket are adapted to receive multiple terminal pins of an IC. According to the zero insertion force arrangement, during the insertion and withdrawal of the IC from the socket, the IC will suffer little or no resistant force from the contacts of the socket. After the pins are inserted into the insertion holes, an operation lever is moved to push a movable plate disposed over the socket housing. The plate then slides a small distance (usually 1 mm) relative to the socket housing, whereby the terminal pins are urged to move toward the contacts and squeeze into a space between two opposite conductive elastic plates comprising the contacts.
Several shortcomings may be perceived in the conventional structure. Typical ZIF sockets are advantageously used to receive large dies or packages, for example a Pentium™ chip. For smaller-scale socket devices, for example a “flip chip” assembly, the dies or packages are too small to be mechanically processed practically with a through-hole type ZIF socket employing the offset method discussed above. In addition, as the package size becomes smaller, the proximity of the pins to one another becomes so close that the pins sometimes come into contact with one another and short the circuit.
The present invention is directed to overcoming, or at least reducing the effects of, one or more of the issues set forth above.
SUMMARY OF INVENTION
In accordance with one aspect of the present invention, a socket device for receiving an IC terminal pin or solder ball is provided. The socket device includes a substrate having an upper surface, a connection pad disposed on the upper surface of the substrate and a first layer disposed on the upper surface and on the connection pad. The first layer includes material having an overall positive coefficient of thermal expansion. The socket device includes a second layer disposed on the first layer. The second layer includes material having an overall negative coefficient of thermal expansion. The socket device also includes a contact hole formed in the first and second layers exposing a portion of the connection pad which is receptive of a pin. In an alternative embodiment the socket device only includes the negative coefficient of thermal expansion layer.


REFERENCES:
patent: 4950173 (1990-08-01), Minemura et al.
patent: 5497545 (1996-03-01), Watanabe et al.
patent: 5607313 (1997-03-01), Nyman
patent: 5641291 (1997-06-01), Sueki et al.
patent: 5919720 (1999-07-01), Leight et al.

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