Issues and Solutions for Thermal Management in Plastic Packages

In current wireless applications, plastic packaging technologies are widely used for the components such as power amplifiers and SIP (system in package) modules. The semiconductor devices in those components dissipate significant amount of heat and requires effective thermal management to ensure the device reliability. The devices (semiconductor dies) in these packages are usually assembled by wire-bond interconnections on PCB substrates and encapsulated with epoxy mold compound (EMC) by a transfer molding process. There are two major paths for thermal dissipations in these plastic packages: a. through the front side of the die and b. through the backside of the die. For low cost plastic packages using conventional molding process, more than 90% of the heat dissipation is through the backside of the die. It is extremely important that the heat path of the system is well designed and optimized. In this paper, technologies for thermal management in this type of packages are discussed. Critical design rules are presented and practical solutions are proposed