Thermal Characteristic Evaluation of Silver and Copper Sintering Materials

In recent years, the demand for power modules has increased rapidly. Sintering materials for die attaching has received remarkable attention from power module industry. Sintering techniques are required to realize for high reliability bonding for wide band gap (WBG) device such as SiC and GaN device. However, their reliability and knowledge of thermal characteristic depends on die attaching material have been a little investigated. In this study, we will discuss difference of thermal characteristic among silver sintering material, copper sintering materials and high lead solder. TO-247 type molded packages were employed for evaluation of die attaching materials. Change in transient thermal resistance were measured after thermal cycling test by T3Ster. The thermal resistance of die attaching portion were analyzed by structure functions. Simulations of transient thermal resistance were performed on the effects of various parameters of the constituent materials on the structure function. The die attach portion of structure function was specified from the simulation. These results indicate that thermal resistance of silver sintering material and copper sintering material portion are lower than that of high lead solder portion and crack resistivity of silver sintering material and copper sintering material are higher than that of high lead solder.