Chris The concerns I'd have would be: 1) any moisture sensitive parts on the bottom side that are getting stressed by the heat of the wave? 2) what is that quantity of solder masking material doing to your cleaner? I'd guess it's clogging your filters if you re-circulate the media, at best you are dumping a fair bit of material down the drain. It might make sense to do for a few, but not in any quantity... I'm sure it's a lot faster, so I can understand why the operator would want to try it (although we would be unhappy they tried it without proper pre-checks). A couple of alternatives that might work better: - get fixtures made to mask the bottom side SMT stuff - we do this and love it. No masking, the SMT is paste attached, good times on building the boards. - or glue the parts on and simply wave 'em so long as there are none that will suffer from the heat have fun! regards, Graham Collins Process Engineer, Northrop Grumman Canada Corporation Halifax (902) 873-2000 ext 6215 >>> [log in to unmask] 03/04/04 03:22PM >>> Hello All- WOW !!! two postings from me in two days... Here is the case: We run a double sided reflow process. We Print, Place, and Reflow the bottom of the boards.. Then Print, paste, and reflow the top side. Since the bottom side is mostly discrete and Resistor networks (unlike the one pictured on Steve's Site) it works well. For the through hole components we hand insert and solder them. I just went down to the wave soldering room and found the operator........... Covering the bottom side components with removable masking material (Chemtronics Brand) and sending the boards through wave. Once Soldered...he removes the masking and all looks well. Question(s); 1) Is this an acceptable practice? 2) What documentation is available to support or disclaim this? 3) What reliability issues are there due to any thermal mismatch? 4) Any leaching of masking material into the solder join causing poor joint integrity? Please advise, Cal P.s. Steve be a fountain; not a drain...keep up the excellent work --------------------------------------------------- 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 -----------------------------------------------------