NEVER, EVER use 'softened' water for the final rinse. Tap water would be safer. Let me explain: Tap water contains (usually) a number of calcium salts, such as carbonate (sparingly soluble), sulfate (ditto) and hydroxide (slaked lime, somewhat more soluble). If used for a final rinse in hard water areas, you will get white "drying marks", caused by these calcium (and/or magnesium) compounds. These are ugly but only very moderately dangerous as only the really soluble calcium salts, such as the halides, ionise readily. The ones usually found in hard water do not ionise readily. Softening is an ion-exchange process where the calcium in these salts are substituted by sodium, and the anions remain the same, so that softened water will contain sodium carbonate, sodium sulfate and sodium hydroxide (caustic soda). These are all highly ionisable and somewhat deliquescent substances, so that even trace amounts on a PC Assembly are potentially dangerous and can cause a number of electrical malfunctions, including dendrites. It is therefore VERY dangerous to use softened water for the final rinses, although it may be used for the wash and first rinse. DI water is also produced by an ion exchange process and, here, the calcium (and other) cations are replaced by hydrogen ions and the carbonate (and other) anions are replaced by hydroxyl ions. The hydrogen and hydroxyl ions combine to form - er - water. So DI water is the ideal medium for at least the last two rinses. In practice, it is used, in most cases, for the whole cleaning process. Also sprach Brian! Brian Macko, Joe @ IEC wrote: > Fellow Techies, > > Hopefully, someone can shed some light on my concern about rinsing > boards (soldered with water soluble flux) with softened water vs. DI > water. > > A board assembly house suggested that it is acceptable to do in-process > rinsing using "softened" water (in an in-line cleaner) and save the "DI > water" rinse for the FINAL in-line cleaning. In-process cleaning would > be for example after the 1st side is soldered on a double sided board. > Seems like a lot of extra work to me switching from softened to DI water. > > Look forward to your comments. > > thanks > joe > > --------------------------------------------------- > Technet Mail List provided as a free 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/html/forum.htm for > additional information, or contact Keach Sasamori at [log in to unmask] or > 847-509-9700 ext.5315 > ----------------------------------------------------- --------------------------------------------------- Technet Mail List provided as a free 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 -----------------------------------------------------