Resistivity of solvent does not change

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    • Bradley59
      April 1, 2014 at 4:59 pm #2897

      We are testing a bunch of boards, and they are all passing. but I noticed on the printouts, the resistivity does not change. That is the beginning and ending resistivity are equal. My boss says “just follow our procedure”. We have been testing boards here like this for many years.

        randall
        April 2, 2014 at 10:13 am #2900

        What kind of system do you have? I have an OM600 SMD and I don’t see any beginning resistivity printed on the test results.

          Bradley59
          April 2, 2014 at 11:15 am #2901

          Hey randall, we use an OM700. We had an OM600,but traded it in years ago to get this machine.

            scschris
            April 7, 2014 at 9:46 am #2903

            Maybe you just have clean boards. Does the resistivity vary from test to test, or is it always the same?

              Bradley59
              April 7, 2014 at 1:26 pm #2907

              NO! The resistivity does not change! always 95MOhm cm
              Does not change from test to test, always the same. I would think that after testing a bunch of boards the solvent would get a little dirty and the readings would change.

                ion-man
                April 8, 2014 at 2:30 pm #2912

                If your resistivity reading are not changing, then something is wrong.
                Perform a chemical verification to see if your system is working.

                  Bradley59
                  April 9, 2014 at 8:53 am #2913

                  Chemical verification? What is that?
                  Unfortunately I don’t have a manual, just a procedure to test the boards.

                    ion-man
                    April 9, 2014 at 10:22 am #2914

                    Chemical verification: Follow your normal procedure, but use 5ml of $3 standardizing solution in place of the circuit board. This will add enough contamination to register on the test. If your system does not register a change in resistivity, then the resistivity circuit is not working.

                    That could be expensive to fix, but the big problem is, all those tests are invalid.

                      Bradley59
                      April 9, 2014 at 1:37 pm #2915

                      Thanks ion-man. Now I have to convince my boss to get some #3 solution so we can verify our system works.
                      If I can’t get some #3, maybe I’ll just squirt some eye drops in there and see what happens.

                        ion-man
                        April 9, 2014 at 4:04 pm #2916

                        Bradley59 – Do not use eye drops.
                        This will contaminate the solution too much and will take a long time for the DI columns to clean the solution.

                        These systems were designed to be conducted by someone trained and not just ‘follow procedure’.
                        At any rate, the procedures should include a chemical verification at the beginning of each day of testing.

                          randall
                          June 28, 2014 at 12:35 pm #2920

                          I know some time has passed, but it bothered by that our OM600 SMD did not print the starting contamination. In short, we upgraded our system to the OM620 , so we can see beginning and ending resistivity readings. This upgrade makes the system comparable to the OM700, but with a larger testcell.

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