A 3D stacked step-down intergrated power module

This paper presents a 3D integrated power module design to effectively save footprint and improve thermal performance. The design reduces the footprint by 40% using a 3D structure in which the inductor is over the top of the regulator. A fixed inductor with a cavity is used to envelop the 3D power module, and the high thermal conductivity of the magnetic core significantly enhances heat dissipation. An efficiency-wise design is applied to the proposed power module and there is a reduction in inductor DC resistance, which can in turn further improve the thermal performance. An analytical thermal model is built to calculate the temperature, 3D FEA (Finite Element Analysis) simulation is also utilized to estimate the improvement in temperature field. A prototype is built to test the electrical and thermal performances as well. The DCR is reduced by more than 30% and the thermal performance is improved by 8-10°C compared with plastic molded power modules.