Preethi,
I suggest that you might have an emulsion being formed.  Check your milky
material by FT-IR and compare to the spectrum of the original Flux Off
material to see if you are getting a buildup of oils.  If so, then the
ultrasonic energy is forming an emulsion of the oils in the cleaning
solution.

Doug Pauls
Rockwell Collins




Preethi Iyer <[log in to unmask]>@ipc.org> on 09/03/2002 10:20:59 AM

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Subject:    [TN] Milkiness in cleaning solution


Hi,
      I am trying to solve a problem related to cleaning of PWB assemblies.
The problem observed is that after ultrasonic cleaning of boards, the
cleaning solution turns milky. At a time five boards (1" square) are
cleaned with fresh cleaning solution (Chemtronics FluxOff). After 25-30
minutes of ultrasonic cleaning, the normally clear solution becomes milky
and the normally shiny and silver solder connections become dull. Ion
chromatography on boards showed Cl and Br ions to be well within the
acceptable limits, but chloride levels in the cleaning solution appears to
be high (~700ppm).

Can anyone provide some insights on why milkiness is occurring??

Thanks in advance
Preethi

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