Developing and mapping of thermally-conductive, electrically-insulating composite coatings for thermal management of electronics

Abstract

The aggressively increased density of electronic devices, such as printed circuit boards (PCBs), demands advanced thermal management solutions. In many cases, it is recommended to coat the PCBs to ensure their protection against environmental hazards. However, traditional coatings are thermally insulating, leading to elevated temperatures and reduced performance. For effective thermal management, the coating materials must exhibit high thermal conductivity (TC > 1 W m⁻¹ K⁻¹) and low electrical conductivity (EC < 10⁻⁷ S cm⁻¹) to prevent short circuits while having suitable viscosity in the liquid state to fit the required method of coating. We mapped these coating properties (EC, TC, and rheology) hence suggesting an essential design tool for most thermal management applications. We found that polymer composite-based coating, loaded with boron nitride (BN) and graphite flake (GF) fillers, provides thermal conductivity of up to 7 W m⁻¹ K⁻¹ while maintaining electrical insulation, suggesting an ideal coating for effective thermal management. The analysis of the mapping data revealed that the hybrid GF/BN composite (17:8 GF:BN v/v) is well-suited for tape casting – a common method to coat the PCBs. The composite has a thermal conductivity of 4 W m⁻¹ K⁻¹ while remaining electrically insulating, thermally stable, and mechanically durable. A model PCB was tape-cast by the selected composite and shows a stable decrease of up to 65 °C of the hot spot temperature. It is suggested that mapping the coating properties is instrumental in future thermal management materials development.