| 摘要 |
PURPOSE:To ease difference between thermal expansion coefficient of a semiconductor device and the heat sink, by laminating three layers into the heat sink. CONSTITUTION:The semiconductor device has a power semiconductor element 3 fixed through a heat sink laminated into three layers over a metal substrate 1. The heat sink 2 consists of plates of copper 4, invar 5 and copper 4 which are extended into given thicknesses and are stamped into given sizes respectively. The thermal expansion coefficient of invar 5 is 1.5X10<-6>/ deg.C. According to this structure, and by selecting ratios of the thicknesses of the three laminated plates of the heat sink being 1:1:1, the thermal expansion coefficient becomes 11X10<-6>/ deg.C, which is smaller than that of the copper 4. Moreover, by selecting the ratios of 1:3:1, the thermal expansion coefficient becomes 6X10<-6>/ deg.C, being near that of silicon. Thus, it is prevented that wax for fixing the silicon power semiconductor element may be deteriorated, and the heat conductivity and therefore heat radiating ability can be improved. |
