Measurement of thermal interface conductance at variable clamping pressures using a steady state method

• Characterization of interface conductance with and without TIM.
• Designed and built a steady state characterization experiment.
• Measured the conductance of six commercial thermal interface materials.
• Investigated how interface conductance varies with clamping pressure.

Thermal conductance of an interface, between aluminum surfaces, was measured at pressures ranging from 0.172 to 2.76 MPa. The conductance was measured for a bare interface as well as with several commercial thermal interface materials (TIMs) applied. A steady state TIM characterization device was developed in house. A total of six different TIMs were tested using this device: Tgrease 880, Tflex 720, Tmate 2905c, Tpcm HP105, Cho-Therm 1671, and Cho-Therm T500. The characterized TIMs showed a very strong dependence on clamping pressure. The conductance of samples at 2.76 MPa were shown to be between 135% and 515% greater than the conductance at 0.172 MPa. Many of the samples showed a near linear increase in conductance while others leveled off at higher pressures. The steady state characterization device was found to have high experimental uncertainty when characterizing high conductance TIM samples (specifically Tgrease 880). It was determined that this uncertainty was mainly the result of inadequate cooling.