Composite Paints with High Content of Metallic Microparticles for Electromagnetic Shielding Purposes

Abstract

This paper describes the technological process used to manufacture composite paints with a high content of metallic microparticles (Al and Fe) for automotive electromagnetic compatibility applications. The thickness of the deposited paint layer was larger for paints with a greater metal content, regardless of the plastic support used for paint deposition. The roughness of paint layers with a greater content of metal particles was about 30%–35% higher than that of layers with a lower metal particle content, regardless of the metal type. The surface roughness of paint layers containing Al was at least 2.5-times higher than that of paint layers containing Fe, an aspect that could be explained by the better formulation of the paint containing Fe. The dielectric loss and conductivity values crucially depend on the plastic substrate used, meaning that the dipolar polarization of the substrate enhances the effect of conductive paints. Based on the dielectric properties measured at 10 kHz, the optimal recipe for efficient electromagnetic compatibility was found to be 20 wt.% Fe powder, deposited on a sandblasted polycarbonate (PC) substrate. It is expected that formulations of paints with a high percentage of metallic particles will effectively compete with traditional plastic metallization technologies.