Nick,

In my opinion pretinning of gold plated leads is important to (1) prevent gold
embrittlement of the solder joint and (2) determine if the leads are solderable prior
to assembly (i.e. gold can be plated over oxidized nickel).  I've seen several
instances of gold imbrittlement associated with soldering to gold plated leads and gold
thick film pads.  The volume fraction of brittle AuSn4 intermetallics tend to be high
due to the 4:1 ration of Sn to Au in the intermetallic compound.  You might want to
check into John Lau's book,  "Solder Joint Reliability", Van Nostrand Reinhold, pp. 205
- 212.

Regards,
Ed Hare
SEM Lab, Inc.
[log in to unmask]

Nick D'Onofrio wrote:

>   We are pre-tinning the gold leads prior to assembly on our military
> products. I'm looking for some constructive data or argument to decide if we
> should continue this practice.
>   My concern would be gold embrittlement in the solder joint and any latent
> failures attributed to this.
>   Any comments or guidance in this matter would appreciated.
>
> Regards,
> Nick D.
>
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