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Air Cooled Semiconductor Chip Module Configuration

IP.com Disclosure Number: IPCOM000089727D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Metreaud, CG: AUTHOR [+2]

Abstract

As shown in Fig. 1, the cap is filled with a material called "FUZZ BUTTON"*. "FUZZ BUTTON" is a resilient mass of fine knitted wire mesh compressed in a die to a desired shape and density. Gold-plated 97% copper and 3% silver is available and may be employed with wire diameters from .003 to .005 inches. Density ratio, after compression, varies from 8% to 13% of solid depending on wire size and compression ratio. In the forming process of the "FUZZ BUTTON" (Fig. 2), a depression is created to provide a nesting place for the chip. The depth of this depression is calculated so that, at assembly of cap and substrate, a light preload force is applied to the chip.

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Air Cooled Semiconductor Chip Module Configuration

As shown in Fig. 1, the cap is filled with a material called "FUZZ BUTTON"*. "FUZZ BUTTON" is a resilient mass of fine knitted wire mesh compressed in a die to a desired shape and density. Gold-plated 97% copper and 3% silver is available and may be employed with wire diameters from .003 to .005 inches. Density ratio, after compression, varies from 8% to 13% of solid depending on wire size and compression ratio. In the forming process of the "FUZZ BUTTON" (Fig. 2), a depression is created to provide a nesting place for the chip. The depth of this depression is calculated so that, at assembly of cap and substrate, a light preload force is applied to the chip.

The thermal conductivity of the "FUZZ BUTTON"-to-chip joint is increased by placing, at the interface, a solder dot, which may be indium, indium-based solder, or any other suitable material or alloy. The solder dot is placed over the chip or into the depression at assembly. In a subsequent operation, which may be coincident with the cap braying, this solder dot reflows to wet the chip and (surface tension phenomenon) infiltrates the "FUZZ BUTTON". The end result of this operation is to form, in intimate contact with the chip, a composite material which has good thermal conductivity, very high creep resistance and a degree of resiliency.

Similarly, the thermal conductivity of the "FUZZ BUTTON"-to-cap interface can be greatly enhanced by coating the inside of the cap (KOVAR**, copper, aluminum, etc.) with solder. At reflow temperature a metallurgical bond is established between the cap and "FUZZ BUTTON". Further, as...