Bravo and Hip Hip Ol' Chap :-)

 

KennyB

  _____  

From: [log in to unmask] [mailto:[log in to unmask]] 
Sent: Thursday, March 04, 2010 2:17 PM
To: TechNet E-Mail Forum; Ken Bloomquist
Subject: Re: [TN] Conformal Coat Over No-Clean Flux

 


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 





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