Study on the Structure–Function Relationship Between Metallized Layer and Self-Healing Morphology in Metallized Film

Abstract

Metallized polypropylene film capacitors (MPPFCs) are widely used in electronic devices for their unique merits: self-healing. This work aims to explore the correlation mechanism between metallized layer structural parameters and self-healing properties in metallized polypropylene film (MPPF). The thicker electrode layer has a more irregular self-healing morphology and needs more energy to restore insulation at the same self-healing area compared to the thinner electrode layer, and the thicker electrode layer has a greater adhesive force, and the root mean square (rms) at $5~\Omega / \square$ thickness is 2.67 times larger than that at 50- $\Omega / \square$ electrode layer thickness. Different surface morphologies of MPPF and different potential differences are the reasons for different self-healing morphologies, which play an important role in self-healing properties, the potential difference at 5- $\Omega / \square$ electrode thickness is 149.2 mV, 1.92 times larger than that at 50- $\Omega / \square$ electrode thickness. The simulation model shows the different stages of plasma development in self-healing, and the plasma develops fast and then slows down in the final stage. The maximum electron temperature in self-healing plasma can reach over 4000 K. The model also explains the influence mechanism of adhesion force on the self-healing plasma and the structure change of the dielectric layer during the plasma process, the carbonized depth in 500 W/m2, thermal flux is $0.19~\mu $ m, but in 1 W/m2, and the carbonized depth is $0.65~\mu $ m, which is a threefold increase.