Steve, Here's the math... 1 DIVIDED BY RESISTANCE (OHM) = CONDUCTANCE (MHO) For example: 1/400K OHMS = .0000025 MHOS or 2.5 uMHO Can't help you with technical aspects of your question. -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Steve Gregory Sent: Thursday, February 26, 2004 12:36 PM To: [log in to unmask] Subject: [TN] Conductivity and Resistivity Correlation 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------