Re: Another scope 7854

 

I originally thought that but when I ran across the problem, removing
the solder revealed that the entire solder to gold interface was a
purple-brown color. I suspect this was a long term effect of whatever
flux Tektronix used during assembly.

On Fri, 5 May 2017 17:23:04 +1200 (NZST), you wrote:

No its just the usual formation of gold-tin intermetallics:

http://www.semlab.com/papers/goldembrittlementofsolderjoints.pdf

http://www.semlab.com/papers/intermetallicsinsolderjoints.pdf

However bonding of aluminium wires to gold pads can result in Aluminium gold intermetallics

One of these intermetallics (AuAl2) is purple (hence the name purple plague) and another (Au5Al2) is white in color.

Bruce

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