12 Mohm rings a bell.... Can't remember anymore... You should contact the vendor.... Washing just smear things around, soluability of water goes down when you have impure (lower resistivity) water = already got some stuff in it...can't dissolve more .... jk >-----Original Message----- >From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis >Sent: Wednesday, April 16, 2003 6:53 AM >To: [log in to unmask] >Subject: Re: [TN] Cleaning Question - Rinse water resistivity? > > >Jason > >The problems may be more complex. I don't know the machine in >question, but I gather it is a closed circuit type with an >in-line DI Column and possibly carbon filter. This is a very >dangerous combination a) because most machines of this type >regenerate the water slower than the water is recontaminated >b) the carbon filter (if fitted) saturates with the non-ionics >from the solvent very rapidly, so these are recirculated >straight through the system and back onto your board. These >will mostly be terpenes but there are also surfactants which >are hygroscopic. c) the drying system may evaporate the water >off, leaving the non-volatile contaminants neatly in place. > >My advice with HCS products, such as EC-7R, is to a) ensure >minimum drag-out from the solvent to the first water wash, by >a long hold period and preferably an air-knife (preferably >with collected and filtered exhaust to prevent operator >exposure to d-limonene). The first wash should be lengthy (say >10 min) with a very powerful pump at a temperature a few >degrees under the flash point of the solvent, for safety. The >first rinse should be open-circuit with water taken from the >final rinse sump. The final rinse should be with freshly >deionised water at 1 uS-cm or better, without recirculation. >Drying should start with mechanical removal, such as powerful >air knives, to blow out contaminated water from under the >components. Only then should you allow evaporation. > >Brian > >Jason Wilson wrote: >> Hi Everyone, >> >> I am a new member to the list and I have a question on cleaning. >> Thanks in advance for any help you can provide. It is much >> appreciated. >> >> What should the value be for rinse water resistivity? The cleaner we >> have is a AAT Corp Emulsonator 9700. >> >> We use an RMA flux (both in wave solder, and in solder paste). The >> solvent we use is EC7R. >> >> Also, we currently rinse for 10 min (+ time to reach resistivity). >> Does this seem low? We are having trouble with board cleanliness. >> >> Once again, thanks for any help provided. >> >> Jason >> >> --------------------------------------------------- >> 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 >> ----------------------------------------------------- >> >> >> >> > >--------------------------------------------------- >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 >----------------------------------------------------- > --------------------------------------------------- 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 -----------------------------------------------------