Paul, Just to make sure we are talking about the same process here, these boards have not been processed thought the screen printer, correct? If so I have seen where improper cleaning practices from mis prints cause trapped solder spheres and result in solder balls. Most of the trapped paste is located around the vias and PTH barrels. Some can become trapped in corners of SMDP (Solder masked defined pads). Just a question to make sure nothing from the process was inducing the solder balls. >>> [log in to unmask] 9/24/2003 6:57:24 AM >>> 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------