Intra- and inter-device passive thermal management using solid-solid Nickel Titanium phase change materials

This paper describes inter- and intra-device phase change material integration approaches using solid-solid Ni50.28Ti49.36 metallic alloys. First, we characterize Ni50.28Ti49.36 solid-solid phase change material using differential scanning calorimetry and Xenon Flash to reveal a material transformation temperature of 75°C, latent heat of 28 J/g, and thermal conductivity between 12 and 16 W/mK. Next, we perform electroless copper plating studies as a prerequisite for downstream printed circuit board integration. Finally, we design, fabricate, and test three unique board designs using x-ray imaging and electronic device heating via infrared thermography. The tested boards include a state of the art copper via board, a first-of-its-kind NiTi-impregnated printed circuit board, and a copper via board with backside NiTi integration. Results from this study demonstrate the ability to electroless plate NiTi, integrate into IPC-6012 E Class 3 printed circuit boards, and (in the test conditions used herein) provide up to a 65% increase in device on-time prior to reaching a critical device temperature. These results set the stage for leap-ahead improvement in the practical implementation of solid-solid thermal energy storage materials.