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Image of Parker Chomerics How to Test a Thermal Interface Material - Slide5

Measuring a material’s thermal conductivity at one thickness is considered a material’s “apparent thermal conductivity”, which includes contact resistance when measured. In order to determine a material’s bulk thermal conductivity, which does not account for any interfacial effects that may impede heat flow, at least two thicknesses of a given sample must be measured. The graph here shows the obtained data in terms of thermal impedance versus thickness. A linear regression on the data will yield the equation, theta equals contact resistance plus 1 over thermal conductivity. The y-intercept is the contact resistance and the slope of the line is the reciprocal of the bulk thermal conductivity. Using this, the material’s bulk thermal conductivity is determined, and this is the value that should be compared between different thermal materials.

PTM Published on: 2020-01-28