Compact Thermal Network Model of the Thermal Interface Material Measurement Apparatus With Multi-Dimensional Heat Flow

Abstract

Accurate prediction of operating temperatures in electronic parts at the component, package, board and system level computational fluid dynamics simulations, has engaged the engineering community for several years. The primary challenge was the difficulty of implementing accurate operating temperature predictions directly into system designs using near-exact physical models (known as detailed thermal models) due to the wide disparity in length scales that result in large computational inefficiencies. A compact thermal model (CTM) attempts to solve this problem by reducing the detailed model to a far less grid intensive representation, while preserving accuracy in predicting the temperatures at key points with a short calculation time. A CTM is condensed using thermal network modeling with thermal resistance and thermal capacitance. This paper focuses on the derivation of compact thermal network models to predict the transient temperature response of complex electronic equipment. The system model is based on a thermal interface material (TIM) measurement apparatus taking into consideration the lateral heat flow in the TIM. The thermal impedance and the temperature difference between the junction and ambient nodes are used to estimate the heat flow division on each heat transfer path. The validity of the dynamic thermal network method and the simple thermal analysis model is confirmed based on the result of the transient thermal analysis. In this paper we describe an application of the dynamic compact thermal network method to analyze the transient thermal response of a TIM measurement apparatus in multi-dimensional heat flow, and we propose a simple modelling procedure for the parametric estimation as a preliminary thermal design tool.