The solution for removing tin metalloresist from the surface of PCBs copper conductors

Abstract

This paper compares velocities of tin and copper etching in solution of different compositions. We identified optimal concentration of based components – nitric acid (4.5 mol / L) and Fe(III) ions (0.18 mol / L). To avoid solution’s worm up and toxic nitric oxides allotment during etching, we propose to add to solution stabilizator-inhibitor based on sulfur- and amino-containing derivatives compounds in concentration 0.015 mol / L. Further addition of benzotriazole and chloride ions results in bright and shiny copper etched surface. Tin and copper ions presence in solution accelerates dissolution’s processes of both metals. Polarization data illustrates that anodic copper dissolution is noticeably lower during etching in the presence of both benzotriazole and stabilizator-inhibitor currents. Finally, the analysis of electron microscopic data shows that copper surface after etching is sufficiently smooth and slightly structured with these solution additives. In contrast, etching in other solutions leads to more developed and structured surfaces.

Keywords

• tin
• etching
• speed
• stabilizer-inhibitor
• metal consumption