Sam, I would ask these questions: How many contacts do you have per board? What is the voltage at the rectifier when the problem occurs? Do you have a totalizer on the rectifier to measure the amp-hours? If the bath is drawing current, but the boards are only plating a thin layer, where is the copper plating (it has to be going somewhere)? Is there evidence of plating on the contacts? I don't have any suggestions regarding the tape mystery, but in my experience, the "burning" around the contact area suggests that either the contact is high resistance (check the resistance from the contact to the board when loading the racks) or there is very thin copper in the area of the contact. Perhaps there is a thin organic film (resist?) on the copper, and the contacts are unable to break through to form a low resistance plating circuit. You might try to etch a board right out of the developer before you pattern plate. If there is residual resist, the etching should be inconsistent. If the board doesn't etch, it won't plate. If there is high resistance in the contact area, the copper will get hot, oxidize, and the copper oxide will dissolve in the plating bath, leaving a "burned" area. It is autocatalytic. As the copper is oxidized, the resistance gets higher, generating more heat, oxidizing more copper, etc. Hope this helps, Dave Anderson *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To subscribe/unsubscribe send a message <to: [log in to unmask]> * * with <subject: subscribe/unsubscribe> and no text in the body. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************