Strategy for a high thermal conductivity and low thermal resistance under compression of oriented carbon fiber with spherical alumina thermal interface material

Thermal pads prepared with pitch-based carbon fibre (CF) orientation have garnered widespread attention due to their generally higher through-plane thermal conductivity. However, these thermal pads must undergo compression during the assembly process. When the compression exceeds a certain threshold, the orientation degree of the CFs inside the thermal pad can change, leading to a reduction in thermal conductivity. In this study, spherical alumina and CF were utilized to optimize thermal transfer stability under compression. The results demonstrate that the composites can still maintain efficient and stable heat transfer even when compressed by 25 %, which represents a more than 60 % improvement compared to pure CF-oriented composites. Furthermore, the relative motion between spherical alumina and CF, driven by their significant morphological differences, enhances the degree of CF orientation during the orientation process. With only 11.8 wt% CF loading, the composite achieved an impressive through-plane thermal conductivity of up to 20.4 W·m−1·K−1.