Reliability of Copper Sintered Interconnects under Extreme Thermal Shock Conditions

Abstract

Copper flakes-based sinter paste showed high reliability under thermal shock conditions. A dense and homogeneous interconnect was realized while sintering for 5 min at 275°C under 15 MPa bonding pressure, with the flakes showing the unique behavior of stacking over each other to realize a dense and homogeneous interconnect. Porosity under 10% could be achieved. The paste could be sintered under a constant nitrogen flow and did not need a fully inert atmosphere during sintering. Under high stress thermal shock cycling of +175/-65°C, the sintered interconnects showed a drop of 25% in the shear strength values after 1000 TST, consistent with observations made with Ag sintering. Thermal conductivity more than 200 W/mK and electrical conductivity of 20 Ms/m is achieved using the Cu sinter paste.