Hi Paul! You said that you've run bare boards through the reflow oven and are getting the solder balls, so to me that would eliminate any issues with solder paste. I've had this happen to me before. It was with a board that was HASL'ed, then as a secondary operation the vias were capped, or tented, on both sides of the fab. During reflow the HASL would of course become liquidous, and pressure would build inside the via, then squirt a little solder ball up on the surface when the pressure would break the mask cap...does it look like the solder balls are coming from via's? In our case when we had that problem, we rejected the fabs. Too much of a risk for a solder ball to come out beneath a part and cause all kinds of problems... -Steve Gregory- > Hi TechNet Gurus, > > Has anyone experienced solder balls resulting from the board fabrication > process? We have been getting them from our offshore supplier for a few months > now and have had to add a wash step to our no-clean process. We know that it's > fro the board because we have run bare boards through the reflow oven using > the normal reflow recipe from that board and we are seeing 25-60 random > solder balls on our 9" x 7", 8 layer, .062", HASL FR4 board. We believe the > problem is caused by uncured solder mask that erupts when exposed to reflow > temperatures but have been unsuccessful trying to eliminate the problem. We have > tried baking the board @ 320 F for anywhere from 1.5 - 6 hours. This has > reduced the number of solder balls to maybe a dozen or less. Anyone have a > suggestion? > Thank you, > Paul Black > Manufacturing Engineer > Kronos > > > --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 -----------------------------------------------------