Numerical analysis of the performance of highly oriented pyrolytic graphite heat spreader in thermal management of microelectronics assemblies

An inverse analysis approach combining numerical and experimental analyses has been utilised to determine the in-situ effective material properties of Highly Oriented Pyrolytic Graphite (HOPG) in a microelectronics test assembly. The approach adopted uses a Finite Element analysis package to determine temperature distribution over a thermal test assembly. A Virtual Design of Experiments approach is used to define a series of analyses with discrete thermal material properties which is used in conjunction with a particle swarm optimisation algorithm to form a response surface function relating temperature to material property values at a number of monitoring points. Experimental data is used to form an error metric which is subsequently minimised to determine effective material properties of the HOPG material. Subsequently a series of studies contrasting the performance of the HOPG material with common heat spreader materials were performed. Results show that the effective thermal property values of the HOPG material seem to be greater than suggested in existing literature and that the HOPG material reduces peak assembly temperatures by a significant amount.