Matte Tin Surface Stain Marks: Important Troubleshooting Tips

Summary for matte tin surface stain marks Discussion

matte tin surface stain marks are being investigated on connector pins that show spots after plating and cannot be removed with water or alcohol. CSKoo says the issue persists despite replacing the post-dip, changing rinsing water, half-making up the tin bath, carbon-treating the nickel bath, and replacing air piping for the air wipe; the parts do not touch each other. Ted Mooney notes that matte tin usually suggests an alkaline stannate bath, though other bath types exist today, and asks whether inspection is happening immediately after plating with no chance for contact or handling. He points out that tin plating can suffer from fretting corrosion, which can create severe discoloration, and says that if the parts are barrel plated, the marks may be expected. When CSKoo asks whether DI water or the tin bath could be responsible, Ted asks for more detail about the air wipe, the air source, and how the parts are held during plating and wiping before drawing conclusions.