Optimization of the Thermally Conductive Low-<i>k</i> Polymer Dielectrics Based on Multisource Free-Volume Effects
Weidi Xu, Ziyang Wang, Hong Cao, Zhou Ling, Niu Jiang, Kai Ke, Zheng‐Ying Liu, Wei Yang, Mingbo Yang
Abstract
Polymers/polymer matrix composites possessing low dielectric constants (low- k polymer dielectrics) contribute to the advance of electronics, for instance, microprocessor chips, mobile phone antennas, and data communication terminals. However, the intrinsic long-chain structural characteristic results in poor thermal conductivities, which draw heat accumulation and undermine the outstanding low- k performance of polymers. Herein, multisource free-volume effects that combine two novel kinds of extra free volume with the known in-cage free volume of polyhedral oligomeric silsesquioxanes (POSSs) are discussed to reduce the capacity for dielectric constant reduction. The multisource free-volume effects of POSSs are associated with the thermal conductive network formed by the hexagonal boron nitride (BN) in the polymer matrix. The results show a decent balance between low- k performance (dielectric constant is 2.08 at 1 MHz and 1.98 at 10 GHz) and thermal conductivity (0.555 W m –1 K –1, 4.91 times the matrix). The results provide a new idea to maximize the free-volume effects of POSSs to optimize dielectric properties together with other desired performances for the dielectrics.