low temp storage with hermatic seal package (dry pack)... pack in a way
according to your forecast usage level (once a year for example or every 6
month).  if it is programmable device, make sure you still has computer
and program to run for it... check solderability every year.  just in case
you see problems, you have time to final alternative, like
re-design-usually take 3-6 month go through qual (not if you want to, but
5 years anything can happen)...my 1.6 cents.
           jk
> Hi Peter - Sue and Richard gave you the critical parameter  = proper
> storage. The two primary processes you want to stop or significantly slow
> down: the oxidation of the solderballs and the absorption of water by the
> BGA laminate/molding. If you use the industry MSL bags designed to control
> moisture diffusion, use desiccant, use an inert gas such as argon or
> nitrogen and then store the bags in a controlled environment, you will
> address both issues and should be able to get a 5 year use life. Most
> folks
> try to cut corners/costs and do things cheaply which dooms their potential
> for success.
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]
>
> On Tue, Apr 7, 2015 at 8:53 AM, Peter G. Houwen <[log in to unmask]>
> wrote:
>
>> We have an FPGA that may not be available to us soon.  One of the
>> options
>> available to us to avoid a redesign is to buy 5 years' supply of the
>> BGA.
>>
>> I'm being asked to analyze the risk factors (and we need an answer today
>> of course)
>>
>> We can easily bake parts for moisture, but what about plating
>> degradation
>> on the balls?  Any other problems I might expect?
>>
>> I assume that even with baking we should expect some yield reduction,
>> but
>> I can't begin to guess how much.
>>
>> Thanks,
>>
>> Pete
>>
>
>
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