Ultrasound-assisted preparation of uniform BiInSn phase change microparticles for enhanced thermal interface materials through in-situ low-temperature soldering

Micro/nano scale metallic phase change materials (mPCM) have attracted interested for constructing thermal interface materials (TIM), which can rapidly transfer heat away and store the latent heat and buffer the tem-perature on the course of the high-power operation. However, it is still a great challenge to prepare mPCM particles in micro/nano scale with uniform size and morphology. Here, we successfully prepared a series of BiInSn spherical particles with adjustable size in the range of 1.21-5.45 mu m through an ultrasonic-assisted bath method. Especially, the BiInSn spherical particles with the uniform size of-5 mu m are prepared under the con-dition of 450 W, 70 degrees C and 40 min. The prepared BiInSn particles maintain the characteristics of low melting point (-61 degrees C) and high latent heat (-29.95 J g-1) of bulk BiInSn, which are further compounded with Al particles to construct a TIM, and a high thermal conductivity (3.24 W m- 1K-1) is reached by adding BiInSn spheres (5 mu m, 5 wt%) as functional fillers. The SEM reveals BiInSn microparticles can melt and bridge the adjacent Al particles to build an efficient heat-conducting network. The mPCM particles will be increasingly used in other fields including 3D printing, sensing, smart materials and so on.