High temperature endurable die attach material for power electronics package — Process challenges

In this paper, silver (Ag) sintering and high temperature lead free solder, bismuth silver (BiAgX) high temperature die attach materials were evaluated and ceramic substrate with gold (Au) metal surface was used. The power module package used in this study consists of four units of power electronics devices. Gate and source pads of these devices are connected to metal clips with high temperature die attach materials. The back of the device is connected to the metal plane (drain) with same high temperature materials. Process development on Ag sintering was carried out and it was successfully attached the device to the cavity. The process development for high temperature solder however has encountered difficulty to achieve good joints between the metal clips and planes on ceramics package and die backside to drain. This is because this high temperature solder has very good wettability on metal surface and gap between non-metal surfaces is large. The Ag sintering materials was selected for further evaluation. The die and metal clip attached samples were subjected to high temperature storage at 250°C for 100 hours in quick reliability. The detailed of (1) process development results on high temperature die attach materials, (2) High temperature storage (HTS) results on Ag sintering and (3) recommended design of the package for high temperature solder were discussed in detailed.