Mechanism of Migration of Sintered Nanosilver at High Temperatures in Dry Air for Electronic Packaging

Low-temperature joining of semiconductor chips by sintering of silver paste is emerging as an alternative lead-free solution for die-attaching power electronic device, particularly for high-temperature applications. However, migration of sintered nanosilver should be fully understood for reliability evaluation. In this paper, we reported our findings and possible mechanism on high-temperature migration of sintered nanosilver on alumina substrate. Oxygen plays an important role in the migration of sintered nanosilver at high temperatures. The migrating silver bridges were presented as discrete silver particles on the surface of alumina substrate. The discrete silver particles preferentially emerged at the boundaries of the alumina particles at the initial stage. The mechanism would be useful to alleviate the migration of sintered nanosilver at high temperatures.