Clamping Force Affected Power Cycling Capability of Double-sided Cooling Transferred IGBT Modules

In practical applications, clamping force must be applied to eliminate the contact thermal resistance between D ouble-sided cooling (DSC) module and heatsink to ensure good heat dissipation performance. The clamping force determines the thermal performance of the DSC module, and also affects its long-term reliability. However, the effect of clamping force on the power cycle life of DSC module is rarely studied. In this paper, Firstly, it was found that among three cooling fixtures, fixture B has better uniformity pressure distribution on the surface of DSC module through Fuji paper test. Secondly, A 3D finite element model of DSC module was established after thermal calibration, the power cycling lifetime was simulated with Coffin-mason lifetime model under different clamping forces and two situations of the same junction temperature fluctuation which $\Delta \boldsymbol{T}_{\mathbf{j}}=100\mathbf{K},\boldsymbol{T}_{\mathrm{j}\max}=150^{\circ}\mathbf{C}$ and the same power loss with $\boldsymbol{P}_{\text{loss}}=603\mathbf{W}$ discussed respectively. Finally, the simulation results show that lower clamping force will lead to a decrease in the lifetime of the module because of the change of temperature distribution, and higher clamping force will cause additional stress on the chip and also increase the system cost.