Accelerated aging and thermal cycling of low melting temperature alloys as wet thermal interface materials

This paper focuses on developing an effective thermal interface material (TIM) using low melt alloys (LMAs) containing gallium (Ga), indium (In), bismuth (Bi) and tin (Sn). The investigation described herein involved the thermal performance evaluation of LMAs after accelerated life cycle testing, which included isothermal aging at 130 degrees C and thermal cycling from -40 degrees C to 80 degrees C. Three alloys (75.5Ga/24.5In, 100Ga, and 51In/32.5Bi/16.5Sn) were chosen as candidate LMA TIMs. The testing methodologies followed ASTM D5470 protocols and the performance of the alloys was compared to commercially available thermal grease and liquid metal TIMs. To understand the LMA-substrate interactions, the alloys were applied to different surfaces (bare copper, nickel coated copper and tungsten coated copper). It was found that the proposed alloys between bare copper substrates were able to survive as long as 2700 h of aging at 130 degrees C and 1400 cycles from -40 degrees C to 80 degrees C without significant performance degradation. (C) 2015 Elsevier Ltd. All rights reserved.