You are NOT paranoid, city water does have ionic contaminants. We used DI
columns here and recycle the water. You may want to test the board in an
ionic contamination tester (Omegameter, Contaminometer, Zero-ion...).

I have a question, why so many drying steps?? Is it actual drying or just
blow-off? Because if it is dried off, there is a good possibility that some
the residue from the flux will stay on the board.

We also use Water Washable flux, we have a simpler cycle:

DI Wash (conductivity = 10 uS max)
DI rinse (conductivity = 5 uS max)
DI rinse (conductivity = 2 uS max)
Air- knife dry
Compressed air blowing (if required)

Hope this helps,

Alain Savard, B.Sc.
Chemical Process Analyst
CAE Electronics Ltd.
e-mail: [log in to unmask]

-----Original Message-----
-----Original Message-----
From: Jean-Francois Bissonnette [mailto:[log in to unmask]]
Sent: Wednesday, June 14, 2000 11:16 AM
To: TechNet E-Mail Forum.
Subject: Board cleaning

I would like to know what is the standard practice for cleaning
assemblies after soldering.  Our supplier uses water washable flux
(337M) and uses city water to wash the boards after soldering in
the following process:

1) Rinse
2) Drying
3) Wash
4) Wash
5) Drying
6) Rinse
7) Drying
8) Pre-Heat
9) Drying
10) Compressed air blowing

Now I believe that the boards should be clean after such a process, but
I'm worried about contaminants that could be found in city water.

Am I paranoid???

JF

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