I have also heard that IPA can crystallize and/or harden rosin flux residues, making them MORE difficult to remove. Is this true as well? -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis Sent: Friday, November 04, 2005 4:34 AM To: [log in to unmask] Subject: Re: [TN] compressed air On request. Even 99% IPA has sufficient impure water in it to have a finite conductivity. To make up the Contaminometer solutions in a past life, I used pro analysi 99.9% reagent grade but I still had to deionise it before mixing with water at <0.06 µS-cm (so-called 18 meg water), to ensure minimal ionics before packing (note I didn't deionise the mixture). Of course, the conductivity rose after packing, in PE containers that had been soaked for 24 hours in similar solution, as the solution will absorb CO2 like gangbusters. The upshot is that IPA does contain unspecified ionic impurities which will be deposited in small quantities after evaporation. The downshot is that I believe these may be harmless in most circumstances with 99% IPA or purer. However, the unspecified contaminants that will be spread over the assembly with an IPA wash MAY be sufficiently ionic to be dangerous. IPA is NOT a good idea but, if it were to be used, it must be followed by a DI water wash and rinse to ensure adequate removal of residual ionics, especially when the history of the returned goods is unknown (they may have been used near stormy seas or salted roads, for example). As you have to wash, anyway, better just to wash with a suitable detergent and forget IPA which is flammable (flash point ~12°C), volatile and toxic (TWA OEL 400 ppm in many countries). Brian dixit Barbara J. Rich wrote: > > > I am looking for any information on using compressed air to blow off > "dust bunnies" on circuit boards coming from the field. > > > > Barb Rich > > Admin. Support Mfg. > > Sanmina-Sci > > 321 S. Taylor Ave. > > 303-264-2009 > > > > > ______________________________________________________________________ > _______ Scanned by Sanmina-SCI eShield > ________________________________ > --------------------------------------------------- > 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 > ----------------------------------------------------- > _____________________________________________ > -- ______________________________________________ Please note new e-mail address [log in to unmask] --------------------------------------------------- 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 -----------------------------------------------------