Devices with pulsing power are often among the most critical to cool due to the temperature-sensitive films they are packaged with. If these films overheat, the resistance running through the package may become altered which complicates the device performance.
There are various common heat sink/solder TIM combinations to choose from depending on the nature of the device. For instance, in the most difficult cases, (those with high frequencies and long thermal cycles) a popular choice is a Copper/Tungsten heat sink used with a TIM closely matched in CTE. One possible choice is gold/germanium preforms, which can be used to create a hermetic package. When the thermal requirements of the pulsing device change however, such as going to a shorter thermal cycle, often the CTE stresses decline and other choices (which are often more economical) in heat sink and solder choice become available.
If you would like help designing your heat sink/TIM design in a pulsed power package, please contact an indium application engineer for material suggestion and design advice.