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July 2014

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From:
Richard Krug <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Richard Krug <[log in to unmask]>
Date:
Mon, 21 Jul 2014 19:28:45 +0000
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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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