Steve, Is the copper current swithed off after the required time or reduced to a very low trickle. We shut down the rectifier at the end of the copper cycle although a strike voltage does not cause adhesion problems, only dull copper. To see if there is an electrical problem, try leaving some dummy panels in the copper solution after plating and see whether any organic or oxide film forms. Do the solutions need carbon treament? Polymers leached from the dry film can redeposit on the copper surface under certain circumstances. I cannot think of anything in the tin-lead which could cause this problem. We put a small amount of lead fluoborate in our pre-dip to drop out any sulphates which might carry over. -- Paul Gould Teknacron Circuits Ltd EMail [log in to unmask]