Steve, Thanks for the response.

Everything I read in the specification linked appears to refer to "greater
than 6 months" as a minimum, more often as "extensive shelf life".
Testing performed indicates the finish performed well even after the
equivalent of 575 days on the shelf.

... I may actually be more confused now that I've reviewed the information
...






On Tue, Aug 13, 2019 at 2:12 PM Steve Gregory <[log in to unmask]> wrote:

> Hi Dave,
>
> Not sure if this helps much or not, but I found this:
>
>
> http://www.circuitinsight.com/pdf/final_finish_specifications_review_ipc_plating_ipc.pdf
>
>
> and I was able find this 4552 which is an old rev because I think it's at
> Rev A now, but if you look starting at page 19 where it talks about aging,
> there's a pretty good bit of discussion there that's interesting...
>
> http://noyancircuits.ir/wp-content/uploads/2018/05/IPC-4552.pdf
>
> Not exactly sure why they wanted to limit it to 6-months based on the way
> it's talked about in that section...
>
> Steve
>
>
>
> On Tue, Aug 13, 2019 at 12:46 PM Dave Schaefer <[log in to unmask]>
> wrote:
>
>> Many older postings on this forum and PCB vendor publications regarding
>> ENIG plating suggest this finish has a very long shelf life, in excess of
>> 12 months. However, the somewhat dated IPC-4552 specification I have
>> suggests the shelf life be limited to 6 months.
>>
>> Can anyone elaborate on what the IPC-4552 recommendations are based upon?
>> Also, what types of failures would one expect to see with PCBs exceeding
>> the recommended shelf life?
>>
>
>
> --
> Steve Gregory
> Kimco Design and Manufacturing
> Process Engineer
> (208) 322-0500 Ext. -3133
>
>
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