Surface analysis of silver-plated circuit boards in a salt-spray environment

By conducting salt-spray tests, we studied the corrosion behaviour and mechanism of printed circuit boards with an immersion Ag surface finish (PCB-ImAg) in polluted environments that contain SO₂and Cl⁻. The polluted environment was similar to the polluted marine atmosphere environment in Qingdao China. A comparison of micrographs of the test specimens revealed that the test specimens containing SO₂and Cl⁻suffered more serious damage. The entire corrosion process resulted in unevenly distributed partial corrosion products at the initial stage. However, this distribution gradually became uniform. The Raman spectroscopic analysis results for the test specimens containing SO₂and Cl⁻show that the corrosion products mainly comprised Cu₄(OH)₆SO₄, Cu₂Cl(OH)₃, Cu₂O, Ag₂O, Ag₂CO₃, Ag₂SO₃and Ag₂SO₄.