The Omega Meter and Zero-Ion both use a DI water and Alcohol mixture. 75% alcohol by volume.
The Omega Meter cleans the test solution to some value greater than 19 Meg ohms and measures the change in solution resistance over time. The measured resistance, temperature, and specific gravity of the solution are factors in a hand calculation to relate the removed contamination to an equivalent amount of salt per square inch or cm.
The Zero-Ion cleans the test solution to one of two preset resistance values, 150 Meg ohms or 50 Meg ohms. The unit then measures the time it takes to return the solution to that resistivity value after a specimen has been added to the solution. Firmware calculates an equivalent of salt per surface area for you and prints the result in a number of formats.
The Omega Meter is less sensitive, in my experience. However, the Zero-Ion can give misleading results because it is so sensitive. There have been occasions where the Zero-Ion measured outrageous levels of contamination because it started to extract contaminates from plastics and the solder mask (especially dry film). The 50 Meg ohm range yields more stable measurements in these cases.
The Omega Meter requires the user to calculate test results by hand. A programmable calculator would be needed for most production line workers.
The temperature of the test solution in the Zero Ion increases when used heavily. The warm test solution is a better solvent than room temperature test solution. I found that the tests results were slightly different when the solution was warm. It can give the impression that things are getting worse, when the test solution is merely getting warm.
The Omega Meter cleans the sample for a set period of time. The time is selected by the user. The manual suggests five minutes. I found that that results from the Zero-Ion and the Omega Meter were more alike when the test was run for 10 to 15 minutes. A test cycle in the Zero-Ion will take from 15 to 40 minutes.
In my opinion, these tools are only useful for setting a benchmark for your cleaning process. Neither give you an absolute measure of contaminates.
The Zero-Ion is easier for a production worker to use, though it can mis-lead users because it is very sensitive.
The Omega Meter is not as easy to use. I found its sensitivity satisfactory
for use as a benchmarking tool.
Subject:
Omega meter v.s. Zero-ion(ZI-100A)
Date:
Mon, 17 Jan 2000 16:36:16 +0900
From:
"F.Shigeoka(Ueno-Seiki)" <[log in to unmask]>
I'm looking for test equipment to measure flux residue.
Does anyone know the difference between Omega metaer and Zero-ion ?
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Fumiaki Shigeoka
[log in to unmask]
Ueno-seiki co.,ltd.