Reliability Improvement of 3.3 kV Full-SiC Power Modules for Power Cycling Tests With Sintered Copper Die Attach Technology

Low conduction and switching loss silicon carbide power modules must be operated at higher maximum junction temperatures utilizing their wide bandgap material properties. This leads to wider temperature range operation and requires higher power cycling reliability. However, silicon carbide power modules showed inferior power cycling test results compared with conventional silicon power modules due to the hard material property of silicon carbide. We have solved this issue by replacing the conventional solder die attach with a new copper sintering die attach. This work developed a sintered copper die attach technology for 175 C-degrees maximum junction temperature operation of 3.3 kV 450 A Full-SiC power modules. Sintered copper die attach changed the failure mode of the power cycling test from the die attach layer crack propagation to lift off of the bond wires on the top electrode. The power cycling test showed an improvement of six times the lifetime compared to the conventional lead-rich solder die attached to SiC modules.