Study of the currently electroless plating industrial process for ABS plastic and improvement proposal of this process to achieve the replacement of chromium etching

Abstract

The process of metallization of non-conductive materials is a generalized technique and for commercial use in sectors such as cosmetics, electronics and automotive. The material used par excellence is acrylonitrile-butadiene-styrene (ABS) plastic. In order to carry out this metallisation, this material is subjected to a line of chemical baths at certain temperatures and immersion time. The first part of the line is where the chemical stage is carried out, its plastic surface is prepared by etching it with a chromium sulfuric solution and then, is activated by a palladium solution. After the activation is done, there is the first deposited coating using a chemical nickel solution. The second part of the line, is where the electrochemical part begins and where the rest of needed metals are deposited. In this report, an initial study of an alternative to the current etching process is carried out where it is possible to prepare the surface without the presence of chrome in etching solution since, this component, in the working conditions where it is used, has a high carcinogenic risk for some users, and causes genetic defects and decreases fertility among others. The European Commission has banned its industrial use since 2011 but due to the lack of alternative solutions, they have repealed the law until new European Community revisions which are estimated to take action in 2020-2021. In order to carry out this new proposal, a complete study of the surface metallisation process in ABS is carried out. To carry out the study of surface roughness at each stage, both the Confocal microscope and the scanning electron microscopy(SEM) are used. Finally, a comparison of the adherence of chemical nickel in etched surfaces between surfaces prepared with chromium etching and surfaces prepared with the new chromium-free etching was carried out with the use of the Crosscut as a qualitative method of industrial use, the Nano scratch technique, and the Calowear test in order to contribute to previous studies as a potential feasible proposal for this global demand within the industry.