Performance of low melt alloys as thermal interface materials

This paper focuses on using low melt alloys (LMAs) containing In, Ga, Sn, and Bi as compliant high performance thermal interface material. The investigation described herein involves in-situ thermal performance of LMAs as a function of applied pressure as well as performance evaluation after accelerated life cycle testing which includes thermal cycling from -40°C to 80°C. Testing methodologies follow ASTM D5470 protocols. Measurements show that LMAs can offer thermal interfacial resistances as low as 0.006 cm²°C/W, and their performance is highly contingent upon the quality of the mating surfaces. The issue of LMA containment and dewetting are discussed along with the solutions to mitigate them. Finally, to compare the performance of LMAs, some commercial TIMs (grease, phase change material, heat spring and thermal pads) were also tested using the same methodology and apparatus.