Fellow, I am trying to look for possible causes for a solder ball problem on the wave process. These boards are practically a Swiss cheese, unmasked 25 mils via holes all over the place, under QFPs, SOIC and everything else, which limits the wave process window. These assemblies don't have SMT on the bottom, wave is used only for TH. We've done everything, checking of flux specific gravity, changed the flux, verified the profile, made sure the flux get activated...Our process uses a foam fluxer and WS flux. What could possibly cause solder balls on the top side? the defect rate is aprox. 2-5 boards with solder balls every 20 boards. Any Ideas? Any comments would be appreciated Jorge Rodriguez Process Engineer Varian Electronics Manufacturing 615 South River Drive Tempe, AZ 85281 Phone: (480) 968-6790 X 4258 Fax: (480) 829-4000 E-mail: [log in to unmask] --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To recieve ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------