Alpha has made an Ohmega meter with built in calculations for over ten years.
No calculators are needed.

Also, if you use the optional solution heater for either of these testers,
the errors induced from random heat changes are gone. The instruments extract
more residue at temperature. You can't heat it for Mil-Spec (I think).

The issue from dry film residues coming out during the test is caused by
developer remaining in the mask after developing and cure. The developer
shows up as PCB contamination on this type of tester. This is one of the many
reasons LPI is more popular than dry film.

Aric Parr
Sr. Process Engineer
Eaton Corporation
1400 S. Livernois
PO Box 5020
Rochester Hills, MI 48308-5020
248 608 7780
[log in to unmask]
---------- Original Text ----------

From: C=US/A=INTERNET/DDA=ID/TechNet(a)IPC.ORG, on 1/18/00 7:40 AM:

Alpha Metals sold the Omega Meter 500. Aqueous Technologies sells the
Zero-Ion. The Omega Meter 500 was replaces by  technology similar to the
Zero-Ion. The new unit is the Ion-O-graph or something like that.

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 ?
---------------------
Fumiaki Shigeoka
[log in to unmask]
Ueno-seiki co.,ltd.

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