The 550F temperature used in thermal stress testing is the same for all laminate materials. BECAUSE they are all soldered the same - as across a wave solder machine. Boards which are vapor phase soldered have a somewhat lower temperature for solder attachment but there is rarely a sign on a bare board that says "NOTE: use solder temp of 475F to solder or barrels will crack" Soldering iron temps are much higher than the 550, but the dwell is less than 10 seconds. The tests run by a laminate mfgr. is on laminate only have little to do with a final board since there are no holes in it. The test is designed to determine how the plated through hole will survive assembly operations and will pick up deficiencies in plating deposits/laminate combinations. Tensile/elongation for a board produced with FR4 may not be adequate for laminates which expand more during soldering. The 550 has been the industry standard for at least 15 years and plating chemistry suppliers are able to meet the requirement for the various types of laminate. When it was changed from the original 500F, the reason was that boards could pass the 500F float and still have barrel cracks during assembly operations. There was a lot of screaming and thrashing initially, but todays product can and does pass the test. When boards are purchased to IPC specifications, the plating deposit in the hole is assumed to be able to pass the thermal stress test. The assembler is then fairly confident that hole wall plating will withstand typical wave soldering operations, 2 -3 surface mount soldering operations and repair/replacement of a component 2 times. My gut reaction is that your board supplier needs to get with their electrolytic chemistry supplier and beef-up the plating deposit to withstand the extra z-axis expansion of the laminate used. Susan Mansilla Technical Director Robisan Lab ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################