In answer to you question, "Do we really need ionic cleanliness testing?", I
would say "yes". Many end users/OEM's/assemblers require ionic cleanliness
test results on the boards sent to them to make sure the boards are clean and
free of contamination. They want to start with clean boards, so the results
of their own ionic cleanliness testing after final assembly can be attributed
to their own processing/cleaning, not to dirty boards that they received.

The ionic cleanliness testers on the market today (the ones using the IPA/DI
water extraction/conductivity method) can offer advantages to PWB
manufacturers, such as:
   1. They are fairly inexpensive
   2. They are easy to maintain
   3. They are easy to use
   4. The test is quick to run (usually about 10 minutes)
   5. The test in non destructive
   6. The test can indicate poor PWB processing (such as undercured solder
mask) if the test results are bad).
   7. Good test results give the PWB manufacturer one more "wam, fuzzy
feeling" that the boards they are shipping to their customers are good.

Both the telecommunications industry (Bellcore with ionic cleanliness
requirements of <6.45 micrograms/square inch) and the military (MIL-P-55110E
with ionic cleanliness requirments of <10.0 micrograms/square inch) require
ionic cleanliness results to meet their specs and many other OEM's have
similar ionic cleanliness requirements (sometimes even more stringent).

The bottom line is that an ionic cleanliness tester is a fairly cheap
"insurance policy" and can save you grief and pin point problems in your own
shop before boards get out to your customers. I'd recommend getting one and
using it.

Hope this helps.

Larry Fisher
Dexter Electronic Materials
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