Silver Sintering Die Attach – Myths & Physics

Silver sintering offers a proven technology to overcome many of the thermal dissipation and high temperature stability challenges associated with power module interconnects (die attach, wire-bonds and heat sink attach). It is rapidly becoming the technology of choice for die attach (and top-side attach) for EV & HEV traction inverter applications. However, there are many different versions of sintering die attach and the process and performance tradeoffs are not clear.This paper strives to clear the mystery behind different versions of silver sintering and other silver based die attach technologies in the running for power packaging and inverter assembly. We describe the bonding mechanism and the resulting material structure for each material technology. The key structure attributes include the nature of interaction between particles (and the metallization at the die and substrate interfaces), porosity and density. Then we relate structure to typical properties achieved with these different materials. Based on material properties we suggest the functional application mission profiles (like power cycling, maximum operating temperature) suitable for each material technology.