High-temperature power devices using SiC as a semiconductor have attracted attention. The author's group had proposed a new packaging structure for the use of SiC power devices. The pure Al board and Ag-nano layer to age mount SiC chip was adopted in this new structure. In addition, Ni-plating was applied on the pure Al board. However, as a result of temperature cycling tests, there appeared cracks generated in Ni-plating. Therefore, the authors proposed an evaluations method to estimate the fatigue life of Ni-plating. And, the durability of this structure was calculated by finite element analysis. The material property was obtained in order to make the real model for FEA. Also, the evaluation of the effect of the thickness of Ni-plating was performed. As a result, it was found that the optimum value of the thickness of Ni-plating.
IntroductionRecently, electric cars, hybrid cars and fuel cell vehicles have changed from current mainstream gasoline-powered vehicles. By electro actuation of cars, technology development of power modules such as battery, motors and inverter has been regarded as important. Semiconductor devices being used to power devices for cars is Si generally. The upper limit of its operating temperature is about 150 . Thus, Si power devices that handle high power are required for large cooling equipment. On the other hand, SiC power devices can be operating even at high temperatures over 250 . Therefore, significant downsizing of cooling equipment and improvement of energy conversion efficiency can be realized. However, working temperature of SiC power devices exceed the melting point of solder materials. Although there are some high melting point solder and brazing material as packaging materials that can work over 250 , it is not ensured reliability of the temperature cycle due to generally hard and poor ductility. Therefore, SiC power devices are required a new packaging structure.