1996 Volume 14 Issue 1 Pages 86-91
An optimum structure of the substrates system for power semiconductor has been investigated based on the themal elastic-plastic finite element method and a performance of substrates system has been verified experimentally.
The thermal stress in ceramics and the thermal conductivity of the substrates are selected as the design objects. The design acceptable region of the substrates is determined by a dielectric break down voltage, a current capacity, a thermal conductivity and a deformation. In this region, the optimization of the substrates with molybdenum-copper layered conductors has been inventigated taking into account the residual stress at bonding process. An example of the optimum structure of the substrates is presented.
The themal conductivity and the reliability under temperature cycle have been evaluated by experimentally. It is confirmed that the degradation of the themal conductivity according to increase of bonding interface is negligible. The reliability of the substrates with the layered conductor has more than ten times compared with the conventional substrates. It is also shown that the optimum structure estimated by the computer simulation agree well with the structure obtained by the experimental results.