A Thermally Enhanced Film Adhesive for Assembling High Power Density Electronic Devices

Abstract

Assembly adhesives play a crucial role in packaging and thermal management design for microelectronics devices. The main function of the adhesives is attaching multiple components together to deliver designed functionalities and ensure integrity and reliability of the device. As requirements for performance and functionality increase, heat generated from these devices increases exponentially. For example, local heat flux can easily exceed 50 W/cm2 for IGBT power modules while it may reach several hundred W/cm2 at active areas for Gallium Nitride (GaN) power amplifiers. However, intrinsic thermal conductivity of polymer-based adhesives is around 0.2 W/mK, which increasingly becomes a thermal bottleneck in high power density electronics devices, especially those used in defense and aerospace systems. Effectively and safely dissipating the high heat and ensuring device reliability have become one of the critical tasks in the development of modern aerospace and defense systems. This paper presents an adhesive film that uses non-electrically conductive particles with high thermal conductivity as fillers in the adhesive to enhance thermal transport. The adhesive film offers an effective thermal conductivity around 0.7 W/mK, which is more than a 3X improvement over conventional assembly adhesives. In addition, the film adhesive has a long work life at ambient conditions with significantly improved processability and controllability, such as bondline thickness control and uniformity, no voids/air pockets, no or minimum resin bleed, etc. They can also be easily converted into preforms with complicated shapes/geometries with typical tolerances less than 10 mil to facilitate assembly processes and ensure a clean and waste free environment.