I generally agree with what you have written here, when speaking of no-clean processing, But I believe the test method is still valid for water soluble fluxes. And I wonder how you would evaluate process results for no-clean fluxing. How can one provide assurance that the processed flux residues are the same as the day the flux process was qualified. > -----Original Message----- > From: TechNet [mailto:[log in to unmask]] On Behalf Of > Mike Fenner > Sent: Thursday, July 17, 2003 10:49 AM > To: [log in to unmask] > Subject: Re: [TN] Ionograph reading for No clean v/s aqueous > processed (wa ter soluble flux) > > > Could the 50 ug figure relate to uncleaned boards which have > been put into the Ionograph? > > If so the number is meaningless as a measure of reliability > or anything else when evaluated against the number for a > cleaned board. The Ionograph was developed as a means of > process control for cleaning rosin based fluxes that met a > now obsolete military flux specification. The best you could > say is that it is probably an indicator for the amount of no > clean flux present. No clean fluxes are defined as harmless > if the residue meets certain criteria, none of which includes > amounts of residual extractable ionics. > > If the number is for a cleaned assembly then all we can > really say for sure is that the boards have a lot more > extractable ionics on them than they could have, [as amply > demonstrated by the fact that the other techniques get lower numbers]. > > If you were using a high solids rosin based RMA flux (say > 35%) of the type around when the Ionograph was invented, and > put an uncleaned board into the Ionograph it would likely go > off scale, the total extractables would be huge. But RMA > fluxes are considered safe if uncleaned. Poorly cleaned they > may not be safe and that was the point of the test: to > provide a means of monitoring cleaning process effectiveness. > > > Regards > > Mike Fenner > > Applications Engineer, European Operations > Indium Corporation > T: + 44 1908 580 400 > M: + 44 7810 526 317 > F: + 44 1908 580 411 > E: [log in to unmask] > W: www.indium.com > Pb-free: www.Pb-Free.com > > > > -----Original Message----- > From: TechNet [mailto:[log in to unmask]]On Behalf Of > Carroll, George > Sent: Tuesday, July 15, 2003 9:09 PM > To: [log in to unmask] > Subject: Re: [TN] Ionograph reading for No clean v/s aqueous > processed (wa ter soluble flux) > > > Ken, > As the previous respondents have indicated, Ionograph results > shouldn't be used as a go-no-go. Taking the process > approach, what were previous results from this vendor? from > other vendors providing similar boards? Are there components > that would tend to hold flux under or near them? That could > contribute to field reliability issues. There may be those > that disagree with me, but 50 sounds a bit steep in > comparison with no-clean boards that I've measured. > > George > --------------------------------------------------- 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 -----------------------------------------------------