Reliability of Sintered Cu Joint on Cu Substrate with or without Ag Metallization

Abstract

Metallic sintering paste, such as silver and copper paste, attracts great attention because of their better performance in next generation wide band gap power device while in comparison with conventional lead-free solder paste [1], [2]. Technologies of metallic sintering paste have been developed to fulfill the severe requirement of next generation wide bandgap high power devices. As copper paste has high thermal conductivity comparing with the conventional lead-free solder and is more cost-friendly than silver paste, together with SiC chip pricing is getting more affordable, it is worthwhile to assess the possibility of applying copper paste onto general electronic devices as well as high power devices. In the present study, the authors investigated the reliability of pressure- assistant sintering copper joint between SBD SiC chips and copper substrates without any metallization (bare copper) and with silver metallization on substrate surface after thermal cycles between -55 °Cx 30 min and 150 °Cx 30 min. Both silver metallized and bare copper substrates had no change at the joint part even after 1000 thermal cycles and showed high reliability. Result of both bare copper and silver metallized samples after power cycles are also discussed. As for power cycle test results, copper sintering joint remains no change even after the wiring portion burned out after over 10000 cycles. Both results indicate copper paste is suitable for electronics with copper and/or silver surface substrate.