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Separator for Semiconductor Soldered Joints

IP.com Disclosure Number: IPCOM000073520D
Original Publication Date: 1970-Dec-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 24K

Publishing Venue

IBM

Related People

Otten, LE: AUTHOR [+2]

Abstract

A plastic material is used to control the distance between a silicon chip and conductive leads joined by moderately high temperature melting solder. Control is achieved by the thickness of the plastic film. The figure shows how a plastic film, cut into a frame shape, maintains a fixed distance between silicon and metallic leads surfaces. Thus fixtured it prevents electrical shorts between leads, and abrasion of leads and silicon surfaces during thermal expansion and contraction.

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Separator for Semiconductor Soldered Joints

A plastic material is used to control the distance between a silicon chip and conductive leads joined by moderately high temperature melting solder. Control is achieved by the thickness of the plastic film. The figure shows how a plastic film, cut into a frame shape, maintains a fixed distance between silicon and metallic leads surfaces. Thus fixtured it prevents electrical shorts between leads, and abrasion of leads and silicon surfaces during thermal expansion and contraction.

Kapton*, a polyimide, is particularly well suited for joint separation since it 1. maintains its physical and chemical integrity during high temperature solder melting operation (to 400 degrees C), 2. is chemically inert during solder flux cleaning operation, 3. has a low coefficiency of expansion (20 10/-6//degrees C),
4. is a good electrical insulator (50 10/9/ cps), 5. is self-lubricating and therefore resists abrasion, and 6. is easily formed into thin sheets.

Other high temperature stable plastics may be substituted. Inorganic material such as Al(2)O(3) in a film form may be used. * Trademark of E. I. du Pont de Nemours & Co.

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