Investigations regarding the influence of soft metal and low melting temperature alloy on thermal contact resistance

Abstract

In this paper, the thermal contact resistance (TCR) of thermal interface materials (TIMs) is experimentally investigated. The effects of contact pressure, heating load and surface roughness are examined in details. Results shows that the low melting temperature alloy (LMTA) can pronouncedly improve the TCR at high heating load condition when compared to indium TIM. Meanwhile, a larger contact pressure or a smoother interface also reduce the TCR effectively. For the solid-state indium TIM, an apparent hysteresis effect is seen for the TCR against contact pressure while there is no hysteresis effect regrading TCR against heating load. The indium TIM is reduced from 0.141 K.W-1 to 0.119 K.W-1 after loading and unloading of contact pressure, showing an apparent hysteresis effect. On the other hand, the TCR of LMTA can be improved by about 13.9-16.0% after increase/decrease heating process. Yet, LMTA contains some overflow issue upon melting. Hence a novel design of LMTA with indium confinement seal is proposed to eliminate overflow problem. Through this design, the TCR remains barely unchanged even after hundred cyclic operations. Additionally, a correlation for predicting the TCM of solid-state TIMs is proposed, and the correlation can predict 98% of experimental data within the error of +/- 30%.