Thermal study of enhanced plastic ball grid array package with flat heat spreader

Three-dimensional finite element simulations are performed to study the thermal performance of a thermally enhanced plastic ball grid array (EPBGA) package with a flat heat spreader adhered to the top surface of the package. Variables available for modification during simulation include heat spreader thickness, heat spreader conductivity and airflow. Specific study is made of the relative effects on thermal resistance of variation of heat spreader conductivity (from 0 to 350 W/m.K), heat spreader thickness (from 0 to 5.5 mm) and airflow speed (from 0 to 3 m/s). Improved thermal performance by use of a heat spreader is confirmed and dangerous package hot spots are minimized. Increasing the thermal conductivity of the heat spreader is found significant at levels up to around 100 W/m.K, but beyond this value the thermal performance improvement is negligible. Increasing heat spreader thickness is found to have a positive effect on thermal performance, but over the range (thickness > 0.2 mm) the improvement is small. Increasing the airflow has a positive effect on thermal performance, but again the level of improvement decreases as the airflow increases.