Jason,

The simplest answer is to pretin the leads in a solder pot. This process "wicks" the gold off
the surface and into the pot. The components should be used as soon as possible after
tinning.

David A. Douthit
Manager
LoCan LLC

JASON CROSS wrote:

> Hello all,
>
> I have a case that recently came up questioning possible gold
> embrittlement in solder joints.  I was wondering if I could bounce a few
>
> numbers off this forum and see what all of you think.  Any help or
> reference material
> would be great.
>
> Ceramic 4 lead oscillator.
> CuNiAu lead finish.
> Component gold plating thickness specs are 12 to 40 microINCHES of gold.
> (I realize that this is quite high)
> Calculations indicate varying % gold by volume of solder to be between
> 1.36% and
> 2.28%, all the way up to possibly as high as 3.13%
> Do you know what the acceptable gold volumes are and the impact to long
> term reliability?
>
> Increasing the volume deposited might only make the solder wick up
> further along the lead, pulling more gold into the joint.  This probably
> wouldn't really help in this particular case.
> Would increasing the pad size AND solder volume (hence trying to
> minimize forcing solder up the lead but rather keeping it flat on a
> larger surface) help?  Would the gold spread evenly to the entire solder
> volume or still concentrate near the lead?
>
> Any help or reference material would be great!
> Regards,
> --
> Jason Cross
> Physical Technology Engineer
> Alcatel Canada, Inc.
> (613) 784-4793
> (888) 662-3425 x 4793
>
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