Doug's answer is 100% correct, you can, BUT ... should you? There is no cut and dried answer. This has already been discussed n* times on this forum and you would get far more info by searching through the archives than we could summarise in a short answer here. In brief, though not as brief as Doug, only YOU can answer the question, yourself, after conducting extensive tests and qualifying both your processes and materials. If you don't wish to do this, the best recommendation is don't coat on top of residues of any nature. Brian * where n is a large integer. Somtawin Pornpottanamas wrote: > Has anyone ever seen white contaminate ( like a crystal) on assembly > boards , between IC lead? I found white residue on some board after > reflow . I try to clean by used IPA, flux removal solvent and also DI > water. But could not remove it. I also found that after we used the > solvent to clean, the white residue increase more. > > Our process used no clean . What is this residue? What type of solvent > that should be use to clean flux residue when we have to rework or > Dedug? > > > > Thanks & Regards, > > > > Somtawin Pornpottanamas > > Material Engineer > > Kimball Electronics (Thailand) > > Tel. 038-401566 ext. 211 > > Fax. 038-495029 > > > > > --------------------------------------------------- > 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 -----------------------------------------------------