The adhesive strength and fractured microstructure of aluminum nitride (AIN) substrate metallized with resistor thick-films followed by firing at 850 degreesC have been investigated via a pull-out rupture test loaded in tension. The AIN substrate used includes the as-received form and an oxidized form that was thermally treated at 1450 degreesC prior to the metallization. The thick-film paste includes both the as-received form (which is an RuO2-based resistor) and a mixture of the paste with varying fractions of sub-micrometer alumina powder (5-20 wt.%) for comparison purposes. When the as-received AIN is used as the substrate, rupture strength decreases monotonically from 1.2 to similar to0.1 MPa as the alumina loading (in the film) increased from 0 to 20 wt.%. The strength, however, remains relatively constant (similar to0.5 MPa) for the pre-oxidized AIN case, i.e. the adhesion is found insensitive to the change of alumina loading. This strength dependency has been compared with their fractured microstructure and the possible fracture mechanism that caused the failure is discussed. (C) 2002 Elsevier Science Ltd and Techna S.r.l. All rights reserved.
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CERAMICS INTERNATIONAL Volume: 28 Issue: 1 Pages: 23-28
