Ingemar: If you have PbCO3, you truly have a problem, this dissolves rapidly in few things, and my best suggestion, ignoring effects on the substrate, would be dilute Nitric acid. This seems a bit extreme, but you need something acidic to dissolve this stuff, and many/most common acids will form insoluble salts with Lead, Nitric is one of the few that will not. Worse, the surface left behind will likely re-oxidize more rapidly than it did originally. RA flux is probably not acidic enough to dissolve the PbCO3, and mixing it with ethanol would probably slow dissolution. Good luck. Rudy Sedlak RD Chemical Company "Ingemar Hernefjord (KC/EMW)" <[log in to unmask]> wrote: We got lots of such growth on CBGA balls recently. After soldering/cleaning: nada. After one week in stock: signs of growth. After one month: unacceptable crystals. Now, being insoluble in water and many solvents, some specialists advise you to mix an RA with ethanol, heat this mixture and dip the part until the crystals vanish. My question to TN is whether there is alternative methods? Some accept PbCO3 growth as being harmless, but this is not our intention, because loose particles are semiconducting and can create leakage current paths. Brian's book "Cleaning and Contamination of Electronics and Assemblies" mention there are five groups of white residues, but, oddly enough, lead carbonate is not included. The chemistry world of soldering residues is so complicated, that I have to ask you for help. Thanks in advance Ingemar Hernefjord Ericsson Microwave Systems --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------- --------------------------------------------------- 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 ----------------------------------------------------- How low will we go? Check out Yahoo! Messenger’s low PC-to-Phone call rates.