Surface-Treated Three-Dimensional Boron Nitride Epoxy Composite Dielectric for Smartphone-Printed Circuit Board Application

Abstract

With the increasing need for efficient heat dissipation in high-end smartphones, the development of dielectric materials for printed circuit boards (PCBs) with high thermal conductivity, a low dielectric constant, and strong adhesion characteristics is crucial. This study aims to design a composite dielectric addressing these often-conflicting properties and to examine its heat dissipation characteristics within an operating smartphone. The composite is formulated using a resin mixture of diglycidyl thioetherdiphenyl, ortho-phenyl phenol novolac glycidyl ether, and bisphenol A diglycidyl ether, combined with surface-treated three-dimensional boron nitride fillers (surf-3D BN fillers). The surf-3D BN fillers, formed from aggregated two-dimensional boron nitride plates, address issues arising from the anisotropic thermal conductivity in individual components. Their surface treatment ensures seamless integration with the native resin network enhancing both thermal and mechanical performance. By carefully adjusting the resin composition and utilizing surf-3D BN fillers, the composite achieves a high thermal conductivity of 5.4 W/m·K, a low dielectric constant of 3.59, and a peel strength of 0.72 kgf/cm. Furthermore, replacing a fraction of the BN fillers with cost-effective SiO₂ fillers maintained the performance while reducing material costs. The composite passed ion migration tests and exhibited superior heat dissipation in smartphone testbeds, making it a promising candidate for next-generation PCB materials in advanced electronic devices.