Steve: Take the inverse of the Siemens reading and that will be in mega ohms. Good DI water should be about 16 mega ohms or about 0.07 micro siemens. Regards, Ramon > -----Original Message----- > From: Blair K. Hogg [SMTP:[log in to unmask]] > Sent: Thursday, February 26, 2004 2:11 PM > To: [log in to unmask] > Subject: Re: [TN] Conductivity and Resistivity Correlation > > Steve, > > Conductivity in Siemens or Mhos is the reciprocal of Resistivity on Ohms. 1 uS conductivity is equal to 1 Mohm resistivity, 2uS is equal to 500kOhm, etc. > > Blair > > > >>> [log in to unmask] 02/26/04 01:35PM >>> > Hi All! > > Is there any chart, formula, or conversion that I can use to correlate a > conductivity reading to a resistivity reading? > > The reason I'm asking is that I have a new batch cleaner that has been up and > running the last three weeks or so. One of the neat things with the cleaner is that during the rinse cycle, it monitors the rinse water resistivity to a > setting that you program in the machine. If it reaches that pre-programmed resistivity setpoint before completing the number of rinse cycles that you program, > it will terminate the rinse cycles and go into the dry cycle. If it never reaches the resistivity setpoint within the number of rinse cycles that you've > programmed, it will display "FAILED" on the touch screen. You can then run another cycle, or start trying to figure out why the boards didn't come clean. > > Well, everything has been going fine with the cleaner up until yesterday. Every batch of boards I ran failed the resistivity setting I had in the machine. > > The manual recommends a setting between 350-750 kohms, I've had my setting at > 550 kohms from the beginning, and everything has been fine. I've had to lower > the setting to 400 kohms so the batches would pass. It's still within the 350-750 kohm range, but I'm curious why all of a sudden things won't pass at 550 > kohm like it's been doing the few weeks. > > So I called tech support for the cleaner, and they feel that my input DI > water may be going bad. I have a US Filters reverse osmosis filtering system that > dumps that water into Ion exchange columns and that water goes directly to my > cleaner. The DI system displays the conductivity of the output water in µS > (micro-siemins). I want to correlate that to resistivity to see if my DI water is > truly going bad. > > Thanks! > > -Steve Gregory- > > --------------------------------------------------- > 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 847-509-9700 ext.5315 > ----------------------------------------------------- > > > ********************************************************************** > This email and any files transmitted with it are confidential and > intended solely for the use of the individual or entity to whom they > are addressed. 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