Effect of isothermal aging at 250 °C on shear strength of joints using Sn-Coated Cu particle paste for high-temperature application

Abstract

Abstract High-temperature joining is a key technology for electronic component assembly and other high-temperature applications. As a die attach process for power devices, we focus on a transient liquid phase (TLP) bonding, which can be operated at a low temperatures while resulting in higher re-melting temperatures of bonded joints. However, some drawbacks of this technology still remain. For example, the duration of this process is too long, up to a few hours, and multiple hours of annealing are required to achieve a thermodynamically stable joint. So we are studying on a TLP bonding using Sn-coated Cu particles to reduce the bonding process time. In this study, we evaluated the effect of isothermal aging at 250 °C on the shear strength of Cu/Cu joints using a Sn-coated Cu particle paste. As a result, a thermally stable joint fully comprising Cu3Sn phase with a dispersion of Cu particles could be obtained after sintering for 30 s at 300 °C under a formic acid atmosphere. The shear strength of the joint before isothermal aging was about 25 MPa and the shear strength after isothermal aging at 250 °C for 1000 h was more than 25 MPa.