I wouldn't be surprised if either solder is going up the barrel or if the via is acting as a heat transfer conduit and reflowing the via. I've seen this with vias near pads on BGA footprints. You might consider covering/plugging the wave side of theses vias with a secondary soldermask. This would reduce heat transfer up the via at wave. Talk to your bare board supplier about this. Density permitting the best option is to move the via out of the pad. [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: Assy: QFP Reflow Author: [log in to unmask] at dell_unix Date: 3/20/97 7:17 AM Hello TechNet: We have a .062", board with a top side QFP (SMT) that is reflowing as the board crosses the wave. Our top side preheat temps have been checked and double checked and is in the 230 degree "F" range. Peak temps shown as the board crosses the wave are well below the 361 degree "F" mark. We have vias in the pads on some of the leads. The QFP is plastic. The board is approximately 3"x5" in size. Density is maybe a little over average. Has anyone out there experienced the same thing with some of your products? We are not seeing a blatant open solder situation, but suttle fractures that will eventually turn to a open situation. Supposedly the SMT guys profiles are ok. They are pretty reliable. The boards are inspected after SMT reflow. What do you think? Is the reflow caused by the solder coming up through the vias? R. Hollandsworth [log in to unmask] *************************************************************************** * 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] * *************************************************************************** *************************************************************************** * 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] * ***************************************************************************