Reliability Tests of Copper Thick-Film Substrates for Power Electronic Applications

Copper thick-film substrates were produced at Fraunhofer IKTS with a commercial copper thick-film paste system and an IKTS proprietary copper paste to compare them with commercial DBC substrates. Thermal shock testing at IKTS resulted in a total failure of the DBC substrates after only 50 cycles. The copper thick-film substrates survived the planned 1000 temperature cycles without damage, though. Power cycling at Fraunhofer IISB showed a significantly lower reliability for copper thick-film substrates compared to the DBC reference. However, a 25 % higher characteristic lifetime was observed for the thick-film substrates compared to the DBC reference.