The Extraction of a Two-Resistor/Two-Capacitor Model for Common Component/Package Design and their Implementation in CFD
When attempting to characterize the thermal performance of an IC component in a numerically efficient manner, the simplest useful compact model is the two-resistor model, created by combining junction-to-case and junction-to-board resistances. Such compact models have several advantages, and are therefore among the most widely used in the electronics industry. However, an overwhelming number of these models are designed for capturing steady-state behavior only. While many investigators have proposed elegant theoretical formulations to address the issue of compact transient models, most of these either cannot, or have not, been implemented in any of the widely used commercial CFD tools. This study proposes a simple technique to extract a two-resistor/two-capacitor (2RC) model from a detailed model using analytical and computational techniques. The ability of the 2RC model to predict the junction and case temperature responses to a step power excitation is investigated by applying the technique to a common package, the Plastic Ball Grid Array (PBGA). The resultant 2RC networks are implemented in a commercial CFD tool and appropriate conclusions are drawn from the results.
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