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July 2014

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Subject:
From:
David Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, David Hillman <[log in to unmask]>
Date:
Mon, 21 Jul 2014 10:27:50 -0500
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Hi Richard - yes, Doug and I call those type of boards, "Barney boards"
(like the children's dinosaur character Barney), as they have a
blue-to-purple visual appearance. In our case, we had someone get carried
away with the cleaning process and over cleaned the assemblies. Depending
on the type of cleaning system/chemistry you are using, you can very
slightly preferentially etch away the tin on the surface of your soldering
joints leaving a lead rich surface. That lead rich surface has a blue -to
purple visual appearance to the human eye (oxide and light
reflection/refraction phenomenon). Its a purely cosmetic issue, if you
touch the solder joint with a soldering iron, you will instantly get the
normal solder joint appearance. But it makes for some very odd looking
solder joints. Do you have any pictures you can send Steve?

Dave Hillman
Rockwell Collins
[log in to unmask]


On Mon, Jul 21, 2014 at 9:29 AM, Richard Krug <[log in to unmask]> wrote:

> We have recently discovered some CCA's with a distinctive, transparent
> blue color on the solder joints.  Viewed perpendicular to the solder joint
> surface, surface looks normal.  The solder surface appears blue when viewed
> at an angle.  I see no residues at up to 30x magnification.  Boards were
> wave soldered using Sn63Pb37 solder with ORH1 flux, then in-line water
> washed with a low concentration of a saponifier as one of our common
> assembly processes.
>
> Any ideas of what the condition is or what caused it?
>
> Dick Krug, CSSBB, CSMTPE
> Lead Process Engineer
> Sparton Brooksville, LLC
> 30167 Power Line Road
> Brooksville, FL  34602-8299
> p (352) 540-4012  (Internal Ext. 2012)
> [log in to unmask]
>
> ______________________________________________________________________
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