Thanks for the nice report Steve (and George).

Dick,

I have gone through the same path in another former life and concluded that the fantastic coloring was not an issue.  Wavesolder typically leaves these colors on the surface of the pot.  ENIG also has left this pattern as is evident in your pictures.

I also had one batch of capacitors which turned blue but we accepted the hardware since the solder joints were properly shaped.  I was working class 2 hardware at the time.

For class 3 or Space, I am not sure I could sell this one.

Phil

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Monday, July 21, 2014 8:43 AM
To: [log in to unmask]
Subject: Re: [TN] Blue Colored Solder Joints - Possible Causes

Hi Dick!

I've seen that too after cleaning with some really good DI water. I had solder joints that turned purple on me one time, but they weren't wave soldered, and it was on a ENIG board and I was using a water soluble SAC
305 paste. Here are some pictures of what I was experiencing:

http://stevezeva.homestead.com/Trippy_Solder.jpg

http://stevezeva.homestead.com/Trippy_Solder_Close.jpg

I could "Buff" the purple color away with a stiff bristled solder joint just as long as I polished the surface well. Here are some before and after pictures of that:

http://stevezeva.homestead.com/Before_Buffing.jpg

http://stevezeva.homestead.com/After_Buffing.jpg

It wasn't a residue, because I measured the cleanliness with an omegameter and it was negligible, and the solder appeared the same.

Then a fellow Technetter; George M. Wenger of Failure Signature & Characterization Lab graciously offered to analyze this for me and here's his report:

http://stevezeva.homestead.com/FSC-5178.ppt

Steve


On Mon, Jul 21, 2014 at 8:29 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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