Evaluation of spreading thermal resistance for heat generating multi-electronic components

The Lee et al.´s equation has been widely used to predict spreading thermal resistance in a single, centered heat source and axi-symmetric condition. However, the eccentric and multiple heat sources are mounted on the base plate in many electronic applications. Thus, it is necessary to determine the spreading thermal resistance for multiple heat sources. For this purpose, we establish the correlation to predict spreading thermal resistance in this study. The correlation which transforms four heat sources to a single equivalent heat source is proposed and then the spreading thermal resistance can be obtained with the Lee et al.´s equation. When the four heat sources are mounted on a square base plate, the correlation is expressed as a function of the heat source size, the length of base plate, and the distance between heat sources. Compared to the results of three-dimensional numerical analysis, the spreading thermal resistance by the proposed correlation is in good agreement within 10 percent accuracy