Been away, so here is late filler. Yes, it can't tell you when things are good or how good, but I suggest monitoring conductivity of final rinse water does have its place as a simple and automatic continuous real time monitor for when things go wrong. In other words if the conductivity goes high then you know immediately that the wheels have come off your process. The actual trip level has to be related on a case basis to SIR, Omegameter etc as you say. Perhaps for completeness we should mention and dismiss PH monitoring as I have seen it being used this way. Regards Mike -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis Sent: Sunday, February 20, 2005 9:04 AM To: [log in to unmask] Subject: Re: [TN] acceptable Final rinse DI water resistivity in a batch type clean er It is impossible to give a cut-and-dried answer as there are far too many variables. Personally, I am STRONGLY opposed to using rinse water conductivity/resistivity as a measure of cleanliness because: a) the water does not know what components and materials you are using and their spacing b) nor does it know how efficient your machine is at cleaning and rinsing, how many nozzles are blocked or spraying badly etc. c) nor does it know whether your drying will be largely mechanical (good) or largely evaporative (bad) d) nor does it know the conditions of use of the end product e) etc. In other words, you cannot use such a parameter as a process quality control. It is not meant for that; it is meant to tell you when the DI columns need regenerating, nothing more nor less. In order to determine all the parameters of a cleaning system, there is only one way, a full series of qualification tests, which includes SIR and ionics (possibly chromatography), according to your individual requirements of reliability of the finished product etc., followed by daily process controls, of which monitoring the resistivity of your final rinse water will be only a minor part. You may find that you may need to go up to 10 megohm-cm or that you can go down to 0.05 megohm-cm. I've seen both these figures in many decades of cleaning experience as the first aqueous cleaning machine manufacturer in Europe and a contamination and SIR tester manufacturer. Believe me! Brian Macko, Joe @ IEC wrote: > Hi, > > > > We are evaluating the cleaning ability of a new batch cleaner, which has the > ability to monitor the resistivity of the actual DI rinse water throughout > the rinse cycle. I checked the archives as well as other sources and it > seems like the consensus ranges from 100K to 750K ohms with most suggesting > 500K ohm as a good, acceptable resistivity level. I am trying to establish > a basis for what is an acceptable final rinse resistivity level for the > boards we process. We use RMA based flux. We also have an incoming DI > rinse water resistivity meter for reference. > > > > Would anyone be so kind as to point me in the right direction? Thanks in > advance. > > > > Joe > > > > > --------------------------------------------------- > 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 ----------------------------------------------------- ::::::::::::::::::::::::::: This email, its content and any files transmitted with it are intended solely for the addressee(s) and may be legally privileged and/or confidential. 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