Hello Badri
Here is one point to note
IPA is available in two grades one is the commercial and the other is the IP
or pharmaceutical one(atleast here in India)   With a heavy price
difference in the two .IPA and water mix easily and almost all alcohols and
'hygroscopic' similar to the phenomenon of men and alcohol perhaps.if you
use the upmarket commercial product you get an unknown amount of water 'free
' with it .when you clean with this stuff you are prone to get patches and
streaks of this white patches so ugly that you repent having cleaned the
boards in the first place
You perhaps need to audit your process and the psychology behind cleaning as
well.If you pay more for the No-clean flux to avoid cleaning why should you
clean in the first placeand add cost not quality to the product      and
that too by use of a bulk cleaning by way of dipbath .Try adding a airknife
,reduce to just required volume of the flux and accept that whatever little
that probably remains on the board as a thin even  layer that   ACTUALLY
helps to protect the board solder like a conformal coat.Some DOE is
certainly required.And afterwards   if you really need to clean small areas
.
use a brush method instead. Companies like Power Integration refrain from
permitting no clean flux mainly coz the High voltages on their device pins
and the unknown grit on the board .Are you a PI user.then straightaway go
for a cleanable powerful flux and use a laundry ...and bake and coat ...and
keep wondering what to do with the spent cleaning solution

Glad to see somebody else alsobeing 'hamletised' toclean or not to
clean............................

Regards
Ajay Moghe
From: "S.Badrinarayanan" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, January 10, 2007 5:07 PM
Subject: [LF] IPA cleaning


Dear All,

After wave soldering we clean our lead free boards with Iso Propyle Alcohol
(IPA)even though we use a no clean flux. The boards are immersed in IPA tank
and cleaned.Recently we are wittnessing white patches on the board after
this
cleaning process. How can I eliminate the white patches. Is there any
alternate cleaning method available. Advance Thanks for the help.

Badri

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