Enhancement on heat transfer and reliability of low melting temperature alloy based thermal interface materials

In this paper, the thermal contact resistance (TCR) of different kinds of thermal interface materials (TIMs) is experimentally investigated. The effect of contact pressure on the thermal resistance of low melting temperature alloy (LMTA) TIMS on different metal substrates has been analyzed in detail. The TCR of all TIMs decreases with the rise of contact pressures. At higher contact pressures, however, the decreasing trend of TCR becomes less pronounced. The adsorption of LMTA by perforated copper foil substrate (PCFS) and copper mesh substrate (CMS) at very high contact pressures removes the leakage phenomenon. However, its thermal resistance is higher than that of samples with a single layer of copper foil substrate (CFS). The PCFS was then parametrically analyzed to obtain the PCF porous ration and LMTA brush weight with the lowest thermal resistance. The results revealed that the TIM samples with a single copper foil substrate exhibited the lowest TCR, but at high pressures, the LMTA is flooded and pumped out. Three different PCFSs were made with 1 mm diameter surface holes and 1.5 mm, 2 mm and 2.5 mm center distances between adjacent holes. All three PCFSs yield the lower thermal resistance than samples with a single layer of CFS at the optimum brush applied LMTA weight. The lowest thermal resistance was achieved by brushing 1.018 g weight of LMTA on a PCF with 19.63% porous ration. The thermal resistance of this sample is only 0.12736 cm2·K·W−1 at 24 MPa.