LOTS of factors could cause this:

What type of connectors?  High pin cout?  Low Standoff?  Plastic or metal?  What type of flux and solder?  What is the cleaning process?  Batch or inline?  Water or Saponifier?  What is the rinse water quality?

Could be "dirty" connectors.  I don't know about the requirements for the connectors to be clean coming in.  Could be trapped flux residues indicating your cleaning process needs improvements to get out the residues from tight spaces / low standoffs, or that you need a chemical to remove non-water soluble contaminants.  Or better rinsing / rinse water to remove saponifier (if used).  Could be cleaning media trapped in or under the connectors. 

If the cleaning process is truly robust, it would also remove residues from the "dirty" connectors too...

If you could find visible residues on the connectors before you touch them you could send them a lab to ID the contaminants.  That would give you what you are up against.

Kevin Glidden
Manufacturing Engineer
Astronics Luminescent Systems Inc.

-----Original Message-----
From: Steven Kelly [mailto:[log in to unmask]] 
Sent: Friday, July 15, 2011 1:20 PM
To: [log in to unmask]
Subject: [TN] Ionic contamination problems

Hi All,
Today is my day for headaches.
We assembled a flex circuit (put a couple of connectors on) and did the Ionic contamination test after our standard cleaning procedure and failed.
After much scratching of heads we decided to take a bare flex - solder it - not add the connectors and test - passed the ionic test easily.
We then took the connectors and put them in the ionic unit - one hit 76 ug/cm2 as received and 6.9 after cleaning. The other was 9.6 ug/cm2 as received and 6.6 after cleaning.
So my question is - do the connector manufacturers have to sign up for a certain cleanliness level and second question what the *&?" do I do now.
Regards Steve Kelly

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