Characterization of a Chromium-Free Passivation Coating on Hot Dip Al-Zn Allay Coated Steel Sheets

The hot dip Al-Zn alloy coated steel sheet was passivated with chromium-free passivation solution which adopted the molybdate and acrylic resin as the main film-forming substances. The surface morphology and corrosion performance of the coating were studied experimentally by using glow discharge optical emission spectroscopy(GD-OES), scanning electron microscopy(SEM) and energy-dispersive X-ray spectroscopy(EDS), polarization curves and the neutral salt spray test. The GD-OES and SEM results show that the molybdate-containing thin organic coating is deposited on the substrate compactly and homogeneously without obvious tiny cracks. The test results of corrosion performance show that the corrosion potential and current density of the passive films decrease obviously in comparison with those of the substrate, and the corrosion resistance of the coating is comparable with that of the chromate passivation coating.

Electrical and Optical Properties of Thermid Polyimide

THERMID, made of acetylene-terminated polyimide oligomers, was developed by National Starch & Chemical Co. It is capable of forming thicker deposits than conventional polyimides. It is a candidate for a broad array of electronic and optoelectronic applications, including passivation coating, alpha-particle barrier, interlayer dielectric, encapsulation of discrete devices and IC, optical waveguide, and multilayer dielectric for thin hybrids. The study and evaluation of electrical and optical properties of THERMID polyimide give more support to their application in the semiconductor industry.