Effect of bonding conditions on shear strength of joints at 200 °C using Sn-coated Cu particle

Abstract

As a recent trend, the silicon carbide (SiC) is of particular interest for semiconductor device. The SiC power device provides the possibility to develop the next-generation power conversion circuit with high efficiency and high power density. Compared with the conventional silicon (Si) device, the SiC device can operate with significant lower power loss and higher operating temperature, which contributes to miniaturization and higher performance of power modules. To assemble these power modules, the high temperature packaging technology such as die attach process is needed. As a die attach process, we focus on a solid-state bonding, which can be operated at a low temperatures. 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 solid-state bonding using Sn-coated Cu particles to reduce the bonding time. In this study, we evaluated the effect of bonding conditions on the shear strength of Cu/Cu joints at 200 t using a Sn-coated Cu particle paste and investigated a high temperature reliability of the joints. As a result, the average shear strength of Cu/Cu joints under a formic acid atmosphere was around 25 MPa at a bonding time of 20 min. Then, the joints had nearly 20MP shear strength after the isothermal aging at 250 t for 1000 h.