Rick,

Are you sure you have the correct standards to measure a thin deposit of immersion gold? You can not use hard gols
standards on your x-ray fluorescence to measure immersion gold.  Also, electroless nickel must be measured with
electroless nickel standards. Call your x-ray fluoresence equipment manufacturer for help, and also toalk to the
immersion gold supplier for advice on measuring such a low thickness.  Our experience is that immersion gold is
difficult to accurately measure. Also, a deposit of 3 to 9 microinches should be visibly good coverage. 1 to 1.5
microinchs should be visually poor coverage, which is reason for rejection. If  the coverage looks visually good, then
I would doubt that it is really as low as 1 to 1.5 inches thick.

Rick Thompson wrote:

> We have an overseas board supplier that is supplying an immersion gold
> finished board that is only 1-1.5 microinches of gold over 100 microinches
> of nickel.  I believe this may be too thin a gold layer for adequate
> protection of the nickel but don't have any objective evidence for this.
> Can anybody give me any feedback or other information sources that might
> support this?  IPC-2221 specifies approximately 3-9 microinches of gold
> which is what we generally require, but I'm looking for additional objective
> evidence for requiring thicker gold deposits.
>
> Thanks in advance.
>
> Rick Thompson
>
> Sr. SMT Process Engineer
> SMTEK International, Inc.
> +1 (805) 532-2800
> [log in to unmask]
>
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