I have similar experience along with Jon on this topic. Intuitively, one would think that the residues would hamper good adhesion of the coating to the substrate, but that's not the case if the flux residue film level is rather low. The uncured/wet coating will actually dissolve some of this residue and disperse them into the coating itself, thereby somewhat cleaning the substrate surface. For adhesive reasons, it's better to have the residue in the coating body rather than the coating to substrate interface. Two points of caution: *Firstly, the flux residues can still become conductive beneath the coating. The same design concerns as for uncoated PWA's are warranted. * Secondly, some coatings with Palladium catalysts can be effected by certain organic acids found in some flux residues. This could result in uncured soft spots of coating, above these areas of flux residue concentrations. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of [log in to unmask] Sent: Wednesday, January 28, 2004 8:49 PM To: [log in to unmask] Subject: Re: [TN] conformal coat over no clean flux residue We coated literally millions of airbag control modules per year for several years with Acrylic, and they always passed every kind of qualification testing. That is a no clean soldering process under AR coating with a safety critical application in very high volume. By His grace, Jon Stop telling God how big your storm is. Instead tell your storm how big your GOD is. --------------------------------------------------- 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 -----------------------------------------------------