Thermally Conductive Yield‐Stress Fluids with Reversible Solid–Liquid Transition Used as Thermal Interface Materials for Heat Dissipation of Chips

Abstract Thermal interface materials (TIMs) paly an indispensable role in improving overall performance of chip, due to the boom of cloud service, machine learning, and artificial intelligence. However, traditional TIMs tend to behave as liquid‐like or solid‐like features, which cannot meet the new requirement of both long‐term stability and excellent thermal‐conduction property. Here, a thermally conductive yield stress fluid consisting of phenyl‐vinyl polydimethylsiloxane polymer and aluminum oxide fillers is reported. This material exhibits reversible liquid–solid transition with a yield‐stress value of 87.32 Pa, and low thermal resistance (0.16 K cm 2 W −1 ). The reversible liquid–solid transition and low thermal resistance are both attributed to the formation of the filler network, as demonstrated by using rheology and two‐phase model. Furthermore, a unifying description of the liquid–solid transition is proposed based on a jamming phase diagram, by considering three factors including filler fraction, temperature, and stress. The yield‐stress fluids combine the desired dispensing due to their liquid‐like behavior and the excellent long‐term stability due to their solid‐like feature. An insight is further provided into the application of this yield‐stress fluids in high‐performance TIMs.