Thermal transfer properties for most TIMs focus on Thermal Conductivity (k). However, the traditional thermal property used with Thermal Dielectric pads is Thermal Impedance (Theta), shown here. From the Thermal Theory Module, the designer knows that Thermal Impedance takes into account real world factors, such as the pressure sensitive adhesive (PSA), Layer Materials, and thermal contact resistance which are prevalent with this type of product family. In addition, because most dielectric pads only come in one thickness, this further lends this Product Family well to using this table of Thermal Impedance (theta). Taking an example of Thermal Conductivity (k) versus Thermal Impedance (theta) for Thermal Dielectric Pads. When looking at the dielectric pad data sheet for Thermal Conductivity (k), the CHO-THERM™ T500 has a lower thermal conductivity than and CHO-THERM 1671. So the1671 should be the better product. Yet, the true thermal performance of the T500 is better than 1671 because T500 has a lower thermal impedance (theta). The reason for the lower thermal impedance is because T500 is thinner than the thicker 1671, even though it has the higher thermal conductivity.