Dick,
Two things come to my mind in looking at the pictures Steve posted, in
the round one, two leads in the lower portion outside ring look to me as
if they may be disturbed or cracked, the white ring, could just be
optical though. Oxidation is my read on the bluish tint, same thing
you get when you tin a brand new solder tip. The other thing I have
noticed is it depends on the type and color range of the illumination,
we used either Halogen (yellow tint), or Led (bright bluish white tint),
ring lights normally, and occasionally we would use polarized lamps
which caused an irredesent bluish tint, and it was very easy to see re
flow strata from uneven wetting.
Pat Goodyear
Retired control technician
On Mon, Jul 21, 2014 at 12:28 PM, Richard Krug wrote:
> I’ve sent copies of pictures to Steve for posting. My samples aren’t
> Barney purple, but appear to be a similar phenomenon.
> Thanks for the inputs.
>
> 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]
>
> From: David Hillman [mailto:[log in to unmask]]
> Sent: Monday, July 21, 2014 11:28 AM
> To: TechNet E-Mail Forum; Richard Krug
> Subject: Re: [TN] Blue Colored Solder Joints - Possible Causes
>
> 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]<mailto:[log in to unmask]>
>
> On Mon, Jul 21, 2014 at 9:29 AM, Richard Krug
> <[log in to unmask]<mailto:[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<tel:%28352%29%20540-4012> (Internal Ext. 2012)
> [log in to unmask]<mailto:[log in to unmask]>
>
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