Problems where you only have one or two panels in a particular lot, and it comes and goes, sometimes with months in between occurrences, are terrible to troubleshoot. From what you describe it sounds like it may be organic contaminants at the copper solder interface. There are several possible sources; in the copper, on the copper, or in the solder. The best way to prevent these nagging intermittent problems is to establish thorough process maintenance procedures and stick to them. Make sure that you're operating at the optimum chemistry conditions and use DI water. Andrew P. Magee - Applications Engineer Rogers - Circuit Materials Unit Tel: (602) 917-5237 Fax: (602) 917-5256 E-Mail: [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: plated Tin/Lead adhesion Author: Steve Allen::(ALLENSAE) at ~FABRIK Date: 1/8/96 12:46 AM From: Steve Allen Date: Mon, Jan 8, 1996 0:46 AM Subject: plated Tin/Lead adhesion To: TechNet Concerning I.R. reflowed plated Tin/Lead on single and double sided PCB's. What can cause poor adhesion of the reflowed Tin/Lead to the plated copper pad? Our plating process is : acid copper/h2o rinse /fluorboric dip/fluorboric Tin/lead plating/ etch/ I.R. reflow. The "problem" is only seen on one or two panels in a particular lot, and comes and goes, sometimes with months in between occurances! Sometimes its detected by a random tape test at pre-mask inspection...sometimes, "unfortunatly" it's found after the customer has assembled the PCB. The solder joints appear to flow very well, but will seperate from the copper if pressure is applied the component lead. No copper is attached to the solder joint that has lifted. The copper pad below is usually somewhat oxidized. We have explored many possible causes, including excessive hold time between steps, etc. I would appreciate any thoughts on this, if anyone has some ideas...?