Heat-resistant durability of AMB substrates for SiC power devices: AlN and Si3N4, which one is thermally strong?

In terms of long-term reliability, the present study investigated the heat-resistant durability of both AlN- and Si₃N₄ cored active metal brazing (AMB) substrates to demonstrate which material can be a better option for use in silicon carbide (SiC) power applications. Interfacial degradation behaviors, peeling strengths, and fracture modes of the AlN- and Si₃N₄-AMB substrates were carried out before and after thermal shock cycling tests. The interfacial microstructure analysis of the AlN- and Si₃N₄-AMB substrates observed different brazing filler metal (BFM) reaction layers depending on the type of ceramic. As a result, it was noteworthy that AlN and Si₃N₄-AMB substrates subjected to repeated thermal shock cycles with Δ190 °C for up to 1000 cycles represented different failure modes with different strength in the peel strength test, respectively. Namely, these two kinds of ceramic type AMB substrates have fundamental differences in thermal shock durability. Nevertheless, cracks between the AMB and ceramic layers were equally caused on the edge side of the AlN and Si₃N₄ cases after the thermal shock test. These cracks are the underlying principles that explain the load-extension plots in the peel strength test. This study systematically discussed the heat-resistant reliability of AMB substrates with AlN and Si₃N₄ as key materials for application to next-generation SiC power devices.