Ramsey, Just to play devil's advocate here, can you consider changing over to no-clean? regards, Bev Christian Nortel Networks > -----Original Message----- > From: Ramsey's [SMTP:[log in to unmask]] > Sent: Friday, November 05, 1999 7:35 PM > To: [log in to unmask] > Subject: [TN] White residue on SMT after vapor cleaning > > A few weeks ago I wrote asking for help on with a white residue problem. > Some technetters ask for a follow-up. Here it is. > Case: White residue appears on ref lowed SMT land patterns after > exposure to vapor cleaning. No white residue appears on wave soldered > land patterns. Even on mixed technology boards. > RMA type paste for SMT. Synthetic Activated flux applied as foam at > solder wave. > Vapor cleaner loaded with Vertrel XMS Plus (HFC, Trans Diclor, and > alcohol). Ultra sonic scrub rinse. > Prior to exposure to vapor process the flux residue is very thin clear > and almost invisible. After cleaning the residue appears as a white > powder where ever there was flux. > We tried a co-solvent Axerel 32 in the boil sump, with board immersion > instead of vapor cleaning. Rinse in Vertrel distillate with Ultrasonic > scrub. Slight improvement. > > Result: We discovered that the residue was flux activators, not rosin. > We experimented with a few flux formulation until we found an old Alpha > Metals paste formulation that cleaned beautifully in the co-solvent > process. 40% Axerel 32 by volume in the boil sump. We have not found an > RMA paste that will clean completely in the traditional vapor process > with Vertrel XMS. > > Did anyone ever hear of an SA solder paste formulation? > > ############################################################## > TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c > ############################################################## > To subscribe/unsubscribe, send a message to [log in to unmask] with > following text in > the body: > To subscribe: SUBSCRIBE TECHNET <your full name> > To unsubscribe: SIGNOFF TECHNET > ############################################################## > Please visit IPC web site (http://www.ipc.org/html/forum.htm) for > additional > information. > If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or > 847-509-9700 ext.5365 > ##############################################################