My
experience with bacteria was similar to Doug's. I don't think we detected
the issue with ROSE test methods at the assembly level but noticed reduced
performance from the mixed beds. And like Doug's we cleaned the heck out of
everything and installed UV in-line to kill life in the water. Here, at the EMPF
today we use a similar system to prevent growth in the lab water. But, I'm not
sure how much good it would do to kill the bacteria once deposited on the
boards, which it sounds like you are proposing. I don't recall even considering
that approach.
Bev
suggested that live contamination brings with it electrolytes. Would merely
killing them remove the contaminate?
I
suspect that you will have to get them off the board, dead or alive. Let us know
what happens.
Hi 'netters,
I have a client that is building extremely high
impedance low voltage assemblies (counting electrons from a photomultiplier
type circuit) that recently are failing test due to "leakage" They are
running water soluble flux with an SMT type aqueous cleaner fed by closed loop
D.I. water 1Meg/cm3 or better. Dynamic Ion testing shows very good results.
They ran a culture and found very high bacteria counts, well beyond fed
drinking water standards.Subsequent cleaning at the end user site (conditions
unknown at this time) seems to resolve the failures. I suggested UV
sterilization (not too expensive/risky) and also to verify "under soldermask"
cleanliness as well as "localized" contamination sites which "average" into
the overall assembly.
My question is if anyone has had any electrical
failures due to bacteria in the rinse water and what solution(s) were
successful. Any other suggestions or suspicions would be
appreciated.
Regards,
Ed Popielarski
QTA Machine
10 Mc Laren, Ste
D
Irvine, Ca. 92618
Phone:949-581-6601
Fax: 949-581-2448
Cel:
949-337-2578
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