Technet, We have encountered what appears to be mask discoloration after wave soldering. The areas of concern coincide with the areas that were exposed selectively by fixtures during wave soldering, dominated by one date code of PCB with a slightly different green (lighter) solder resist. Other data code (same PCB vendor) with darker solder resist waved at the same time have less/no discoloration. We have not seen this issue before this build. There was no PCB vendor change & (known) process &. Process details: Reflow (x2 times) Wave solder: preheat (120/130C), solder temp 260C, with fixture Flux: no clean, halide free Top side max PCB temp 110C Wash&Rinse cycle 8min at 130F in DI with saponifier, Dry 1 min at 100F Following link shows PCB images with white milky masks after wave soldering AND WASH. It does not seem to be surface residues (IPA has no effect). PCB vendor is currently investigating. http://members.shaw.ca/ppwlee1/Images/Mask_color1.jpg http://members.shaw.ca/ppwlee1/Images/Mask_color2.jpg http://members.shaw.ca/ppwlee1/Images/Mask_color3.jpg Has anyone seen this before? Any idea on what causes the mask discoloration and its potential impact on the assembly? Any comment is greatly appreciated. Rgds, Peter --------------------------------------------------- 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 847-615-7100 ext.2815 -----------------------------------------------------