Text version of the page

â–¼

Selecting Dielectric Materials

Dielectric Layer

The technology of Thermal Clad resides in the dielectric layer.It is the key element for optimizing performance in your application. The dielectric is a proprietary polymer/ceramic blend that gives Thermal Clad its excellent electrical isolation properties and low thermal impedance.The polymer is chosen for its electrical isolation properties, abilityto resist thermal aging, and high bond strengths. The ceramic filler enhances thermal conductivity and maintains high dielectric strength. The result is a layer of isolation which can maintain these properties even at 0.003" (75µm) thickness. This guide will help you select the best dielectric to suit your needs for watt density, electrical isolation and operating temperature environment.

Electrical Isolation

Dielectrics are available in thicknesses from 0.003" (75µm) to0.006" (150µm), depending on your isolation needs. See electrical design considerations on pages 18-19 to help determine which thickness is appropriate for your application.

Thermal Impedance Determines Watt Density

Thermal impedance is the only measurement that matters indetermining the watt density capability of your application because it measures the temperature drop across the stack-up for each watt of heat flow. Lower thermal impedance results in lower junction temperatures. The lower the thermal impedance, the more efficiently heat travels out of the components.High thermal conductivity is relevant to your application whenthe thickness of the dielectric material is taken into consideration. Impedance to heat flow is proportional to the ratio of thickness to thermal conductivity.

TOTAL IMPEDANCE= Sample Thickness + Interfacial ResistanceThermal Conductivity

Lower Thermal Impedance = LowerJunctionTemperatures

6