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Eliminating Via To Via Cracks in Multilayer Alumina Ceramic Substrates

IP.com Disclosure Number: IPCOM000088423D
Original Publication Date: 1977-Jun-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Lehman, HS: AUTHOR [+2]

Abstract

In the fabrication of multilayer alumina ceramic substrates containing molybdenum (Mo) metallurgy for via interconnection of layers, cracks could propagate from one via to the next, thereby forming so-called via-to-via cracks. These cracks, which are basically the result of thermal expansion mismatch between molybdenum metallurgy and alumina ceramic, could be eliminated by surface compression of the substrate.

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Eliminating Via To Via Cracks in Multilayer Alumina Ceramic Substrates

In the fabrication of multilayer alumina ceramic substrates containing molybdenum (Mo) metallurgy for via interconnection of layers, cracks could propagate from one via to the next, thereby forming so-called via-to-via cracks. These cracks, which are basically the result of thermal expansion mismatch between molybdenum metallurgy and alumina ceramic, could be eliminated by surface compression of the substrate.

Surface compression of the alumina substrate containing Mo vias is achieved by laminating greensheets of alumina with outer layers of such lower expansion materials as mullite and firing the composite substrate around 1560 Degrees C. Since the thermal expansion of mullite is about 20 x 10/7// Degrees C lower than that of the interior alumina body, surface compression is developed. Substrates fabricated this way, with 100% mullite and with 89% mullite plus 11% glass for the surface layer, have resulted in the elimination of via-to-via cracks.

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