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Browse Prior Art Database

Formation of Bismuth Containing Cu Vias in Ceramic Packages

IP.com Disclosure Number: IPCOM000103237D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 28K

Publishing Venue

IBM

Related People

Chen, J: AUTHOR [+3]

Abstract

Disclosed is an approach which uses bismuth, that is known to have a negative thermal expansion coefficient, in conjunction of common conductor materials, such as Cu, to form composite conductors in ceramic packages for the purpose of thermal expansion matching. This helps to alleviate reliability problems, such as conductor cracking or delamination, caused by thermal expansion mismatch.

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This is the abbreviated version, containing approximately 100% of the total text.

Formation of Bismuth Containing Cu Vias in Ceramic Packages

      Disclosed is an approach which uses bismuth, that is known to
have a negative thermal expansion coefficient, in conjunction of
common conductor materials, such as Cu, to form composite conductors
in ceramic packages for the purpose of thermal expansion matching.
This helps to alleviate reliability problems, such as conductor
cracking or delamination, caused by thermal expansion mismatch.

      In this approach, bismuth (or bismuth-containing alloys) is
pre-mixed with Cu paste before ceramic sintering to form composite
conductors.  The composite conductors can also be formed by
infiltrating conductors which are porous after ceramic sintering with
bismuth or bismuth-containing alloys.

      Using this approach, we were able to create conducting through
holes with a thermal expansion coefficient far below that of Cu and
an electrical conductivity approximating that of Cu.

      Disclosed anonymously.