Highly thermal-fatigue resistant Si<inf>3</inf>N<inf>4</inf> substrates with excellent mechanical and thermal properties

Abstract

Thermal fatigue of active metal brazing (AMB) substrates was investigated under severe heat cycle condition from −40°C to 250°C using developed silicon nitride ceramics (Si 3 N 4 ) with high thermal conductivity and excellent fracture toughness as well as conventional Si 3 N 4 and aluminum nitrides (AIN). No peeling off of copper layer was observed even after 1000 cycles for the AMB substrates with various Si 3 N 4 , whereas the AIN-AMB substrates exhibited copper delamination only after 50 cycles. Bending strengths of the AMB substrates with conventional Si 3 N 4 decreased gradually with thermal cycles. By contrast, degradation in the bending strength of the AMB substrates with developed Si 3 N 4 was negligible. It was found that the developed Si 3 N 4 -AMB substrate with superior mechanical and thermal performance could endure harsh thermal environments.