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Forming an Insulating Skin on Conducting Ceramic Composite

IP.com Disclosure Number: IPCOM000039598D
Original Publication Date: 1987-Jul-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Brownlow, JM: AUTHOR [+2]

Abstract

In certain electronic components it is desired to join an active device to an insulating ceramic substrate. If that substrate happens to be a conducting ceramic composite, it must be overlayed with an insulating layer. This layer has adhesion and stress problems. The need for an added insulating layer can be avoided by creating an insulating skin on the ceramic composite by deeply etching away the conducting portion of the composite. This leaves the insulating network structure as insulating layer, and forms micropores for the enhanced adhesion of the next layer. An example of this idea is a composite made of conducting titanium carbide in an aluminum oxide insulating network. One effective removal method is to make the substrate the anode in an electrolyte of 5% sodium phosphate tribasic and 5% sodium chloride.

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Forming an Insulating Skin on Conducting Ceramic Composite

In certain electronic components it is desired to join an active device to an insulating ceramic substrate. If that substrate happens to be a conducting ceramic composite, it must be overlayed with an insulating layer. This layer has adhesion and stress problems. The need for an added insulating layer can be avoided by creating an insulating skin on the ceramic composite by deeply etching away the conducting portion of the composite. This leaves the insulating network structure as insulating layer, and forms micropores for the enhanced adhesion of the next layer. An example of this idea is a composite made of conducting titanium carbide in an aluminum oxide insulating network. One effective removal method is to make the substrate the anode in an electrolyte of 5% sodium phosphate tribasic and 5% sodium chloride. The voltage is raised to 50 or 100 volts for 1 to 4 hours. TiC is etched out, leaving insulating A12O3 . Some unconnected TiC grains also remain, but these are isolated from one another and do not form an electrically continuous path. The insulating skin which is formed will withstand 200 volts.

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