Thermal-resistance considerations in the design of semiconductor devices

The problem of heat generation in a semiconductor device is discussed, and it is shown that the thermal characteristics of regions remote from p-n junctions may have an important bearing on the operation of the device. To decrease the thermal resistance of a device, the obvious solution is to use as the base of the capsule a material of high thermal conductivity. Such materials do not lend themselves to making satisfactory welded hermetic seals. Composite base structures have therefore been examined both theoretically and experimentally and found to give an improved device performance. The problems associated with transient flow of heat in a device are discussed and significant differences are found when the heat dissipation takes place for short or long periods.