Thermal Cycling of Sintered Silver (Ag) Joint as Die-Attach Material

Abstract

Sintered silver is a promising die-attach material capable of operating at temperatures of more than 200°C. However, while sintering reliably bonds Ag paste on Ag-plated substrate, reliability studies are needed to understand the behavior of this sintered bond on copper and direct bond copper (DBC) substrates. Here, we thermally cycled micron-Ag and nano-Ag joints created via sintering on Cu, DBC, and Ag-plated substrates between − 65°C and 150°C in order to understand their evolving microstructures and reliability. Short periods at high temperature did not oxidize the substrate, but the absence of copper oxides did not prevent adhesive failure of the nano-Ag joint at the Cu interface. We found that Ag filler size influences pore shapes, pore sizes, and shear strength; the micron-Ag joint produced a mixture of irregular and regular spherical pore shapes that reduced bond strength more than the predominantly spherical pores present in the nano-Ag joint.