>On Thu, 2008-01-24 at 18:12 -0500, Chris Smolinski wrote:
>>  A friend of mine is reporting a fairly high rate of failures with
>>  Xilinx 9500 series CPLDs. From what he describes, boards are built,
>>  tested, everything is OK, they're put on the shelf in anti-static
>>  bags, then some time later (say a few months), they're finding that a
>>  CPLD has gone bad. They have to replace it, re-programming doesn't
>>  help. This is happening on several different board designs. I don't
>>  know all the details, but he did report that for example, input pins
>>  are pulled low by the CPLD.
>>
>>  The first thing that comes to mind is electrostatic damage, as it is
>>  winter. But thinking back, I've used these parts myself in several
>>  designs, and don't recall seeing abnormal failure rates, even with
>>  lax electrostatic protection. Some RoHS effect, perhaps? Any other
>>  ideas?
>
>I can't offer any ideas, but I can report that I've been using the 9500
>series for a few years now and have never experienced a failure. Heck,
>one of them even survived being put in the PLCC socket incorrectly, it
>cooked, but seemed to work fine afterwards.

Yes, my experience is that they're very robust, which is why I am 
surprised they're having failures. They are socketing them also. 
Taking them out of the socket and replacing them doesn't help, so it 
isn't corrosion on the sockets/pins. Neither does re-programming, 
they have to replace the CPLD. And they're not failing in use, but 
rather failing after they have been tested, and then put into 
storage. Very very weird.

-- 

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Chris Smolinski
Black Cat Systems
http://www.blackcatsystems.com
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