Development of TLP-AI Technology to realize high temperature operation of power module 2019-01-0607

SiC power devices are promising components for the power module assembled in the automobile power control unit due to their low-power loss operation. Also they have high thermostable characteristics which are expected to tolerate high temperature operation, widening the range that the conventional Si device has limited. While, the packaging technology is also needed to improve the thermo-stability to derive the full potential of SiC power device, especially the device bonding which is directly related to the device thermally and physically. TLP bonding is one of the promising technologies for the high temperature operation because its bonding layer has high melting point. But there is a problem that characteristic of TLP bonding layer causes the damage to the power device. This paper describes a new bonding technology, transient liquid phase bonding with an aluminum interlayer (TLP-Ai), stress relaxation which possesses high ductility leading to stress relaxation, preventing the device damage at high temperature. Also, the thermal characteristics such as high melting point and high thermal conductivity contribute to the high temperature operation. . This method lowers the device stress by approximately 44% compared to the conventional TLP bonding, and increases the thermal conductivity at least twice higher than conventional soldering. In experiment, after thermal cycling test (-40°C  175°C 1,000 cycles) no cracks are observed in the aluminum interlayer. Moreover, after power cycling test (30°C  175°C 100,000 cycles), the crack propagation is reduced approximately 80% compared to conventional solder bonding.