The basic assumption being made here is that the Residue Release Rate of all these different flux families into the 75/25 v/v 2-propanol/water test solution is the same. All the original work, choice of test time etc. was based on the release rate of solvent cleaned rosin flux residues. Northern Telecom studied this release rate issue and found that while well over 90% of rosin flux residues came off in the 15 min. test period, it took about 2 hours for an equivalent amount of water soluble flux residue to come off the boards into solution. So yes, you can get get very low Ionograph numbers with WSF in 15 minutes, but only because you are measuring a very small fraction of the residue that is present-- its the 80-90% that is still left on the board after the test is run that is going to harm your product! For those that are interested in this, I have a greatly expanded version of the history of ionic measurements plus references to key studies in this area. The Navy did an exhaustive study of using ionics to measure water soluble fusing fluids, concluded that it was not a relevant test method; concluded that SIR much better for WSFF or WSF. This was the same group that developed the ionic test in the first place. All of this has been published. Bill Kenyon Global Centre Consulting P.O. Box 553, Montchanin, DE 19710 USA Tel: 302.652.4272 Fax: 302.652.5701 Cell: 302.377.4272 email: [log in to unmask] --------------------------------------------------- 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 -----------------------------------------------------