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Enhanced Adhesion and Thermal Conductivity of Epoxy Sealant

IP.com Disclosure Number: IPCOM000060401D
Original Publication Date: 1986-Apr-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Irish, GH: AUTHOR [+2]

Abstract

An increase of 1300% in adhesion (peel strength) of cured epoxy to aluminum is achieved by blending at least 25% by weight of high density, hot pressed boron nitride powder into the liquid epoxy just prior to application. Also, the thermal conductivity of the cured epoxy is increased 800% by this addition of boron nitride. These changes in properties of epoxy are especially beneficial when the material is to be used in packaging of semiconductor device chips. A semiconductor chip solder-bonded to wiring on a ceramic substrate having connecting pins embedded is covered by an aluminum cap which is epoxy-bonded to the substrate edges. The epoxy is applied to the back of the substrate as well as to its edges and is referred to as the "epoxy backseal".

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Enhanced Adhesion and Thermal Conductivity of Epoxy Sealant

An increase of 1300% in adhesion (peel strength) of cured epoxy to aluminum is achieved by blending at least 25% by weight of high density, hot pressed boron nitride powder into the liquid epoxy just prior to application. Also, the thermal conductivity of the cured epoxy is increased 800% by this addition of boron nitride. These changes in properties of epoxy are especially beneficial when the material is to be used in packaging of semiconductor device chips. A semiconductor chip solder-bonded to wiring on a ceramic substrate having connecting pins embedded is covered by an aluminum cap which is epoxy- bonded to the substrate edges. The epoxy is applied to the back of the substrate as well as to its edges and is referred to as the "epoxy backseal". Heat generated by the semiconductor chip, when in use, is better dissipated when the connecting material between the substrate and the aluminum cap is thermally conductive. The "backseal" material must not be electrically conductive, however, since the connecting pins are all contacted by the material. The factor of eight increase in thermal conductivity of the backseal material by adding 25% by weight boron nitride powder, without changing electrical conductivity measurably, extends the usefulness of the packaging method to higher chip power dissipation applications. The integrity of the seal between the backseal material, the substrate, and the aluminum cap...