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Chip Packaging Structure With Enhanced Cooling

IP.com Disclosure Number: IPCOM000089261D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Berndlmaier, E: AUTHOR [+5]

Abstract

In Fig. 1 each bellows forms a sealed cavity containing a small amount of liquid metal. The function of the stud is (a) to provide a large surface area interface with the liquid metal to promote heat conduction to the cap, (b) to minimize the amount of liquid metal required, and (c) to provide lateral support when thin plastic bellows are used.

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Chip Packaging Structure With Enhanced Cooling

In Fig. 1 each bellows forms a sealed cavity containing a small amount of liquid metal. The function of the stud is (a) to provide a large surface area interface with the liquid metal to promote heat conduction to the cap, (b) to minimize the amount of liquid metal required, and (c) to provide lateral support when thin plastic bellows are used.

Metal bellows of required characteristics (small size, low spring rate, thin wall) are available and may be employed.

At assembly a light hydraulic pressure is created within the bellows and is maintained through the life of the device. This pressure is calculated not to exceed the creep strength of the C-4 joints. Entrapped air, which can be minimized at assembly, will tend to locate within the convolutions of the bellows and on the upside of a normally mounted assembly (horizontal), and thus have no effect on the thermal efficiency of the device. Referring to Fig. 2, an alternate design provides an air space, or pressure compensation chamber, within the body of the stud.

Fig. 2A illustrates a diaphragm structure including a plurality of integral bellows structures. As depicted in Fig. 2, the diaphragm structure of Fig. 2A may be utilized with a suitable retainer plate.

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