is your board used on mars?  or your board used on pulp and paper, or  
your board is used under mining/oil and gas condition?  if it is and  
you have no other protection at system level for your PWA (conformal  
coating or hermetic seal), you might need to consider it.  (your  
designer can tell you that).  IMHO.
jk
On Aug 14, 2018, at 9:34 AM, FTL Quality wrote:

> Hello Dave,
>
> Thanks for the reply, is the FOS test appropriate for any common  
> PCB plated finish?
>
> Thanks,
>
> ALsdair
>
> -----Original Message----- From: David Hillman
> Sent: Tuesday, August 14, 2018 1:29 PM
> To: [log in to unmask]
> Subject: Re: [TN] Flowers of Sulfur test
>
> Hello Alasdair - I would think that a FOS test on an immersion silver
> surface finish would not be an appropriate test as silver and  
> sulfur do not
> like each other. The appropriate testing for printed circuit board  
> surface
> finishes would be found in the IPC-45XX specification series.
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]
>
> On Tue, Aug 14, 2018 at 7:25 AM, FTL Quality  
> <[log in to unmask]
>> wrote:
>
>> We've been asked whether we use the flowers of sulfur test to  
>> check our
>> plating.
>>
>> Does anyone use this test for ENig, Pure Hard Gold, or Silver  
>> plating?
>>
>> I've got doubts as to whether completing this test would give any  
>> sort of
>> answer in any case as ENig is known to not withstand normal humidity
>> testing.
>>
>> Thanks,
>>
>> Alasdair