Thermally Conductive and Electrically Insulating Thermal Interface Materials for Advanced Packaging: From Filler and Interface Engineering to Thermal Networks

Thermal interface materials (TIMs) that combine efficient heat transport with electrical insulation are increasingly important for three‐dimensional integration and high‐power electronic packaging. Existing reviews commonly organize the field by filler type or treat surface modification, filler alignment, and network construction as separate strategies, obscuring their coupling across length scales. Here, we present a hierarchical design framework linking physical fundamentals, filler/interface engineering, and thermal‐network engineering. We first examine phonon transport, electrical‐failure mechanisms, area‐normalized thermal resistance, and effective‐medium models to define the constraints governing filler selection. We then compare oxide and nitride ceramics, carbon‐based materials, and emerging high‐thermal‐conductivity candidates, with emphasis on anisotropy, defect chemistry, processability, and electrical compatibility. Filler functionalization, spheroidization, and core–shell design are subsequently analyzed together with orientational alignment, multicomponent hybridization, and three‐dimensional network construction. Particular attention is given to the coupled effects of composite thermal conductivity, interfacial thermal resistance, bond‐line thickness, electrical insulation, processability, and long‐term reliability. Finally, we discuss six research directions spanning unconventional fillers, adaptive interfaces, multiscale computation, advanced manufacturing, chemical interphase design, and sustainable package co‐design. This framework shifts TIM development from isolated property maximization toward package‐relevant thermal–electrical–mechanical co‐optimization.