Approach Towards Accurate Modeling of Thermal Resistance in Thermal Management of PCB

Due to the importance of modeling thermal transmission for microelectronic packages, thermal resistance is considered as a symbolic parameter in thermal management. A great deal of work has been done on developing thermal network models for thermal resistance. Using a network to link junction node and various representative nodes, a network model can take into account of the distribution of heat transfer along paths and also describe the internal uneven situation of components. As a result, thermal network models are flexibly suitable to different situations, binging in reasonably accurate results. This paper reports a modeling study of thermal resistance using a software package, as part of a parallel investigation between experiment and modeling. The focus is put on the two-resistor compact model, though other models are also examined for comparing purpose. Three approaches, computer modeling, theoretical analysis and experimental verification, are involved. The purpose is to gain a realization of the composition and the effect of thermal resistance through an integrative process among the three approaches mentioned above, so that the suitable method can be identified. Different models of thermal resistance are computationally tested and comparably analyzed for a comprehensive understanding of the characteristics of various models. It is found that, after a combinative consideration of effectiveness and efficiency, the two-resistor model can lead to a reasonably good result with adequate cost-efficiency. The parameters of two-resistor model are set up after intensive measures based on theoretical principles and against experimental results. The results agree well with experiments and theoretical analysis. Not only is the current problem solved, but also a realization on how to express thermal resistance in modeling is obtained, paving the way for following on modeling of other types of PCBs. By interpreting the mechanism of thermal resistance and exploring modeling methods, this paper demonstrates an approach for modeling thermal resistance for thermal management of PCBs. Relevant practices and experiences are referable for researchers and engineers in designing heat transfer aisles and improving thermal reliability of PCBs.