Failure investigation of a Ag sinter-joining SiC power device under harsh cycling conditions

Abstract

In this work, we evaluated reliability of a SiC power module under harsh thermal cycling (-50~200 °C) and power cycling (Tj = 200 °C) test conditions. The SiC power device was assembled by Ag sinter-joining die attach, bonding ribbon, and imide resin molding. The Ag sintered layer shows a mud-crack structure after 1000 thermal cycling test (TCT) due to a CTE mismatch between SiC and Ag, whereas cracks happened at ribbon-bonding interface during power cycling test (PCT). Based on the present results, it can be concluded that the Ag sinter-joining is competent in SiC power devices for high-temperature applications. Meanwhile, it is necessary to update the topside bonding technology in order to accommodate with severe operation conditions.