We regularly use components 5, 10,and sometimes even 15-20 years old - not by choice but to support spares and legacy designs :-)

There are a few strategies:

1) Hope - store the parts as you normally do, bake before use and then hope they solder - not recommended.

2) Store in a nitrogen atmosphere - this can either by in a controlled nitrogen filled dry storage cabinet - in which case no need for baking and no oxidisation
        Or you can back-flush and your regular MBB (in which case you may need to do some maintenance as these bags are nor impermeable for life and so you may need to rinse and replace every year or so).

3) Allow for the fact that you will have to 'refresh' the balls before use - i.e. remove and replace them in batches as you need to use them, this has the downside that it can get expensive and although the companies that offer this as a professional service are very good, the component still needs to see a couple of extra heat cycles.


We favour option 2, but some of our customers will ask for option 3.


Sue Knight
Project Engineer
E-mail: [log in to unmask]
Web: www.sti-limited.com
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Peter G. Houwen
Sent: 07 April 2015 14:54
To: [log in to unmask]
Subject: [TN] 5 year old BGAs

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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