Thermomechanical reliability of a silver nano-colloid die attach for high temperature applications

• Determined thermal fatigue properties of a silver nanoparticle colloid die attach.
• Determined electrical properties of silver nanoparticle colloid die attach.
• Derived model for fatigue life of silver nanoparticle colloid die attach.
• Compared fatigue life to low temperature sintered silver attach.

The last several years have seen the advent of silicon carbide (SiC) power devices operating at temperatures well above 125 °C. These devices have the potential to provide higher switching speed and lower on-state losses with higher thermal conductivity. Developing reliable technologies for packaging is now the main hurdle to successful operation of SiC based power electronics at high temperature. This paper evaluates a novel silver nano-particle colloid material that has been suggested for use as a die attachment for high temperature environments. The material synthesis together with fundamental mechanical and electrical properties is presented relative to the low temperature sintering process. Using thermal fatigue data measured for this material, a low cycle fatigue curve for the silver nano-particle colloid was developed. A Coffin–Manson relationship was derived for the solder; which together with calculated strains in the joint, allows the low cycle fatigue life of the die attachment to be predicted.