Elastic Half-Space Theory-Based Distributed-Press-Pack Packaging Technology for Power Module With Balanced Thermal Stress

Abstract

In this paper, the distributed-press-pack (DPP) packaging technology is developed to achieve balanced thermal stress on the chips. Under the current lumped-press-pack (LPP) style, the mechanical stress distribution on the chips, which is inherently uneven and coupled with thermal stress distribution, can be described with elastic half-space theoretical model. By decentralizing the lumped pressing load and positioning the loads evenly, a matrix of clamping array is formulated and the mechanical stress distribution is compared under different clamping ways. Then, a 3*3 clamping method that meets the trade-off between balanced stress distribution and the packaging cost is chosen. Meanwhile, the busbar and heatsinks are integrated to improve the power density of the power module. Finally, a DPP prototype is implemented. By varying the pressure around the chips and heating them, the thermal distribution between parallel chips inside the prototype is compared and the effect of proposed elastic half-space theory based DPP packaging technology on the thermal stress balance is verified. 1