No doubt, the Technet forum tis a great thing.  I seem to recall us 
discussing this issue at length about a year or so ago.  I suspect that if 
you search the archives, you would find the thread.

Along the lines of what you ask.  While Rockwell does use low residues 
fluxes (low residue is a flux, no-clean is a process) and we clean them, 
we also have a very successful "reduced clean" where we solder on parts 
that are either intolerant to our water wash process or it is "bloody 
inconvenient (I am feeling British this afternoon).  We often conformallly 
coat over those residues, usually Alpha Telecore Plus or Kester 245 )both 
ROL0), successfully with Humiseal 1B31 acrylic or Humiseal 1H20AR1 
acrylic-urethane.  I know that you are looking at using urethanes, but 
don't use those very often.

Anyone who knows Hillman or I know we test the crap out something before 
we ever allow it on product, so we looked at combinations of cored wire 
flux with additive fluxes, and the resultant combinations with the 
coatings, mostly the solvents in the coatings which would have a tendency 
to soak into the residues, potentially altering the chemical nature of the 
resulting mix.

I think that you will largely find that solvent based coatings, such as 
one part urethanes or acrylics generally adhere pretty well to low solids 
flux residues, but again, depends on the flux.

I can and does work, but like anything, ya gotta do the testing, test 
drive the car, kick the tires, etc. 

If'n ya knows what yur doin', life is great.  If not, experience is an 
expensive educator, but often very thorough.

Doug Pauls



Ken Bloomquist <[log in to unmask]> 
Sent by: TechNet <[log in to unmask]>
03/04/2010 03:38 PM
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Re: [TN] Conformal Coat Over No-Clean Flux






Doug,

One of the great things about the TechNet is the traction you can get from
the efforts of people who have gone before. While I know that "good" 
testing
is required for every application I was hoping that I would here something
like; "I had great results using a Xylene based Polyurethane moisture cure
coating over ROLO no-clean flux." Or "I tried Xylene based Polyurethane
moisture cure coating over ROLO no-clean flux and it was a disaster!"

I know that my application will be a little different than anyone else's 
and
require testing but was just hoping for a baseline.

KennyB

-----Original Message-----
From: Douglas Pauls [mailto:[log in to unmask]] 
Sent: Thursday, March 04, 2010 1:42 PM
To: [log in to unmask]
Subject: Re: [TN] Conformal Coat Over No-Clean Flux

Jon,
While that is true, that only relates to the compatibility between fluxes. 

 Seldom do you have flux vendors also providing coatings.  It is the 
product of the combined flux residues with the coating, especially the 
solvent carrier, that you have to watch out for.

Doug Pauls





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