Discretized TIM thermal modelling technique for capturing non-uniform pressure distribution effects

Pressure distribution across the Thermal Interface Materials) TIM is non uniform due to inherent surface irregularities of package top surface and heat sink bottom surface. Non uniform pressure distribution causes thermal impedance variations. Thermal modeling of TIM to capture surface irregularities and effect of non-uniform pressure distribution is challenging. This paper introduces a technique to capture non uniform pressure distribution. Novelty of this technique is, using pressure map data of the TIM contact area and thermal impedance vs pressure data of the TIM to capture non-uniform pressure distribution effects. Python script is used for handling large amount of pressure map data and developing discretized TIM thermal model in ECXML format. ECXML format thermal model is imported into system level CFD model through ECXML format interface provided by CFD tool. System level CFD simulations are performed using the TIM thermal model. Parametric study is performed using three pressure maps, to study the effect of non-uniform pressure distribution of TIM for demonstrating the technique. Challenges and limitations of extracting accurate pressure maps through experimentations and numerical modeling errors are discussed in the paper.