There are primarily three Selection Criteria for Dielectric pads. First, Thermal Transfer Properties refers to both thermal impedance, the traditional way these products have been specified, as well as thermal conductivity, a relatively new way to look at the product. Secondly, Dielectric properties refers to the voltage breakdown rating of each pad. This can be both for dry interfaces and wet or high humidity environments. Finally, Cost and Volume of part refers to price drivers for each material as well as if the material type lends itself well to high volume production.