System-Level Thermal Modeling and Its Significance in Electronics Packaging

Thermal management of electronics has been a major limiting factor in achieving high-power, high-performance systems. Isolating various heat dissipating components from each other becomes significantly difficult as increasingly higher packaging densities are targeted. Thus, components with different heat dissipation rates and allowable temperatures are thermally coupled due to increased proximity. The packaging configuration, positioning of the active components and the chosen heat removal techniques play an important role in determining the overall power consumption, efficiency, reliability and expected lifetime. Consequently, evaluation of the electro-thermal characteristics on the system-level becomes as critical as the component-level in order to adequately capture the effects that components have on each other. Also, through a system-level evaluation, limiting quantities such as the maximum ambient temperature, the cooling sequence of the components and the flow routing can be ascertained for a given assembly. Optimization of the design, selection of the appropriate working fluid and prevention of catastrophic failures such as thermal runaway, can be possible through utilization of a system-level thermal model. This study presents a MATLAB based system-level thermal model with an iterative solver that incorporates temperature dependent characteristics. The model is used to design and optimize the thermal management approach of a high-power full bridge DC-DC converter module. Comparison of various flow routing configurations and heat removal modes' effect on overall performance, along with other advantageous conclusions drawn through several design iterations are performed using the system-level model and are illustrated in detail.