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Low Temperature Alloy Seal for Electronic Modules

IP.com Disclosure Number: IPCOM000087316D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Pittwood, DG: AUTHOR

Abstract

There is shown a hermetic seal for electronic module enclosures. A eutectic alloy of bismuth, lead, tin and cadmium, called CERROBEND*, is melted, cast into an annular cavity that communicates between the module base and its cover, and allowed to solidify.

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Low Temperature Alloy Seal for Electronic Modules

There is shown a hermetic seal for electronic module enclosures. A eutectic alloy of bismuth, lead, tin and cadmium, called CERROBEND*, is melted, cast into an annular cavity that communicates between the module base and its cover, and allowed to solidify.

Among the desirable properties of this particular alloy for this application is the fact that it expands upon solidification. Thus, the solidification process actually produces a pressure connection between the alloy, the walls of the grooved ring, and the cover. Sharp ridges are machined on the cover, as shown, to further enhance this effect for sealing purposes by providing points of pressure concentration.

When the annular ring and cover are constructed of brass or copper, the seal is still further improved by wetting of these parts by the molten CERROBEND, establishing a metallurgical bond, also.

Due to the low melt temperature of the alloy (185 Degrees F), casting the seal or remelting it to open the module for service poses no thermal problems to the components inside. Also, the alloy is fully compatible with FREON** type coolants that are often used in such modules. * Trademark of Cerro De Pasco Corp. ** Trademark of E. I. du Pont de Nemours & Co.

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