High voltage semiconductor power module is the most significant equipment in new energy industry. As the voltage level increases, the problem of insulation breakdown caused by electric field distortion at the triple point of the power module becomes more and more prominent. Dielectric functionally-graded-materials (d-FGM) can effectively uniformize the field strength, but its construction method and principle in the complex structure of power module are still unclear. To this end, based on electrophoretic technology, the deposition law of d-FGM under different voltage application time was explored through simulation and experiment. Furthermore, the frequency domain spectroscopy (FDS) curves of the samples under different voltages amplitudes were analyzed using Maxwell’s loss theory. The experimental results show that with the increase of voltage application time under a uniform electric field, the particles will distort the electric field to form a chain-like structure near the negative electrode and move to the positive electrode to form a deposition layer. On the other hand, with the increase of the applied voltage amplitude, the FDS curve of the sample increases in the whole frequency band, which can be explained by Maxwell’s interface polarization theory.

power module;high voltage;electric field stress optimization;dielectric functionally graded materials