Hi David, The original premise was that no-clean's won't be cleaned; therefore, many no-clean fluxes were not formulated to assist the cleaning process. Add a long residence time and cleaning is likely even more difficult. Today you can buy cleanable-no-clean's... In addition to what Rudy shares regarding acids, we have seen the organic acids in the water soluble flux adhere to the resin mixture of the no-clean "low residue" flux. The water soluble flux "sticks" to the no-clean residue. The water-soluble/no-clean's organic-acid/resin mixture then becomes very difficult to remove with water. At that point, our recommendation is to remove both the no-clean and water soluble flux with an appropriate wash chemistry. What part of the part is the acid unfriendly to? Have a Great Week! Shean Dalton Austin American Technology www.aat-corp.com <http://www.aat-corp.com> 512-335-6400 -----Original Message----- From: R Sedlak Sent: 6/27/2005 12:02 PM To: [log in to unmask] Subject: Re: [TN] Flux residues--Why David: No-clean residue is SUPPOSED to be hard to remove, this means it is unreactive, and thus will not corrode the part.... When you mix it with water soluble flux (which usually contain small amounts of strong acid), you reactivate the organic acids in the residues, and they can be quite corrosive, and unlike the water soluble flux acids, they do not vaporize during soldering, and this organic acid combined with the acid in the water soluble flux can work together to corrode. Hope this helps. Rudy Sedlak RD Chemical Company David Tremmel <[log in to unmask]> wrote: Technetters, I have received some microBGAs which I have to reball and they have a no-clean flux residue which is difficult to remove. Also, when it comes in contact with our water-soluble flux it creates an acid which is not very 'friendly' to the part. Would any of the chemical gurus care to edify one of the uneducated ones why no-clean flux, when dried and allowed to set for a couple of months is so difficult to completely remove and what possible acids or chemicals are created when it is combined with water-soluble flux (type ORM1)? As always, I appreciate the responses I receive. David Tremmel Technical Manager BT Mexico _________________________________________________________________ ¿Cuánto vale tu auto? Tips para mantener tu carro. ¡De todo en MSN Latino Autos! http://latino.msn.com/autos/ --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------- Yahoo! Sports --------------------------------------------------- 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 ----------------------------------------------------- Rekindle the Rivalries. Sign up for Fantasy Football --------------------------------------------------- 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 -----------------------------------------------------