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Lead electroplating color

Hi,

I am a metal finisher doing job-work for many electronics manufacturing customers. I do Tin, Lead and Tin-lead plating to suit the customer specifications. Recently, one of our customer has rejected the lead plated copper strip due to change of color at their premises. It seems that the change of color from grey to blue, brown etc., is taking place after 12-24 hours.

I use a fluoborate based bath with only the grain refiner additive from a proprietary source. Recently, the supplier of grain refiner said that his product color has been changed and he will supply me only with that color. He assured me that there won't be any problems in the quality of our lead deposits.

Now is this color change of our plated deposit is related to the change in color of the grain refiner? I feel that the material is introducing impurities into the bath and after we do organic contamination treatment, this color change stops. Again the color change happens after a month and organic contamination treatment is done..the cycle has gone on for the last 3 times? I've to conclusively prove that this grain refiner is causing the problem or is there any other reason for this? Any comments will be highly useful.

Regards,

Ranjan Thomas Kurien
Metal Finisher - Bangalore, Karnataka, India
2004