Atomic layer deposition coated polymer films with enhanced high-temperature dielectric strength suitable for film capacitors

Although polymer film capacitors are widely used in power electronic systems, their high-temperature performance deterioration severely limits their further application. This work shows conclusively that ultrathin alumina coating by atomic layer deposition (ALD) can significantly improve the thermal stability and capacitance stability of polypropylene (PP) films at temperatures above 140 degrees C. We demonstrate for the first time the ALD coating enhancement on breakdown strength (>600 V/mu m) and elastic modulus of both crystalline PP and amorphous polyetherimide (PEI) at higher temperatures. The discharged energy density of ALD alumina-coated PP and PEI films reached 4.1 J/cm(3) at 140 degrees C, 2.6 J/cm(3) at 150 degrees C, respectively, which is much higher than uncoated films. The finite element simulation also manifests the consistency in dielectric strength enhancement that may be attributed to the increased elastic modulus due to the alumina coating. This new perspective provides an effective pathway to obtain ultrathin surface coating for dielectric polymer films with enhanced dielectric strength, elastic modulus, and thermal stability promising higher temperature application.

Automated summary

This study demonstrates that ultrathin alumina coating by atomic layer deposition (ALD) can greatly enhance the thermal stability and capacitance stability of polymer film capacitors at high temperatures. The ALD alumina-coated films exhibit improved breakdown strength, elastic modulus, and discharged energy density compared to uncoated films.