The concentration of IPA in the Test Solvent will influence the test results. The Test Solvent
should be 75 % IPA, +/- 3%. Because IPA will evaporate quicker than H2O, the concentration
of IPA will tend to decrease with time. This concentration should be checked, and if necessary
Non-ionic contaminates such as polymers from samples can accumulate in the Test Solvent.
These contaminates can cause unpredictable test results. They can damage the DI-Filter by
covering the surface of the internal resin beads. If this happens, your only recourse is to
replace both the DI-filters and the Test Solvent. If the system cannot be calibrated after
installing new DI-Filters, then you should replace the Test Solvent (aka 75i).
The actual concentration of IPA in the Test Solvent is important for accurate contamination
results. The Test Solvent is also referred to as “Extract Solution” and”75i”. Its purpose is to
wash off, or extract contaminates from a circuit board during the test. It consists of 75% by
volume IsoPropyl alcohol (IPA) and 25% by volume Di-water (D-H20). You should verify the
solvent’s IPA concentration periodically (weekly), or when you change the solvent. The IPA
concentration should be 73 to 77 percent.
To make an adjustment to the Test Solvent, you will need to measure the Specific Gravity of the Test Solvent using a hydrometer.