counterfeit Xilinx ?

Jon Elson wrote:

> This was a very small batch of parts, so it doesn't make much sense to
> spend a lot of money on it.  I still have no idea whether there was any
> funny business, or these parts were just mishandled in some way to cause 
> them to deteriorate.  A number of them would not do the master mode 
> configuration, so that can't be a speed grade problem.  But, half of 
> them work!  I still don't know if I have some kind of process problem 
> here in my shop, but I am coming around to think it is not something I
> caused here.

That reminds me of another scam :  Quantity padding.

Someone in the supply line decides to 'pad the numbers', and
the report I remember had lower failures on the end of tubes, and
higher failures (non blank OTP devices) in the centres.
They hope the user will shrug it off.

Can you pop the top on some failures and look at the die ?

-jg

John_H wrote:
> Jon Elson wrote:
> 
>>This was a very small batch of parts, so it doesn't make much sense to
>>spend a lot of money on it.  I still have no idea whether there was any
>>funny business, or these parts were just mishandled in some way to cause
>>them to deteriorate.  A number of them would not do the master mode
>>configuration, so that can't be a speed grade problem.  But, half of
>>them work!  I still don't know if I have some kind of process problem
>>here in my shop, but I am coming around to think it is not something I
>>caused here.
>>
>>Jon
> 
> 
> Some ideas:
> Did you bake the parts before assembly?
> Are you hand-soldering the deviecs?

I did not bake the initial run of parts before IR reflow.  They were 
"pretty" dry, however.  I did hand solder the replacements, and had one
dead chip that way, too.  I don't think this is a moisture problem.
I have had such a low rate of possible ESD problems in the past (maybe 3 
chips in 10 years) that I doubt I suddenly have ESD.

Anyway, I have made enormous progress on migrating to Spartan 2E, so I 
won't be buying any more of these 5V Spartan parts.  It means throwing 
away some unpopulated boards, but it is worth it to not have to deal 
with these failures and rework.

Jon

Jim Granville wrote:
> Jon Elson wrote:
> 
>> This was a very small batch of parts, so it doesn't make much sense to
>> spend a lot of money on it.  I still have no idea whether there was any
>> funny business, or these parts were just mishandled in some way to 
>> cause them to deteriorate.  A number of them would not do the master 
>> mode configuration, so that can't be a speed grade problem.  But, half 
>> of them work!  I still don't know if I have some kind of process 
>> problem here in my shop, but I am coming around to think it is not 
>> something I
>> caused here.
> 
> 
> That reminds me of another scam :  Quantity padding.
> 
> Someone in the supply line decides to 'pad the numbers', and
> the report I remember had lower failures on the end of tubes, and
> higher failures (non blank OTP devices) in the centres.
> They hope the user will shrug it off.
> 
> Can you pop the top on some failures and look at the die ?
I've never been very successful at opening up Xilinx pacakges.  The epoxy is
harder than steel (well, at least really abrasive) and I don't have 
something that will dissolve it.  These are TQFP's, so there's no metal
lid.  They come in waffle trays, so there are a lot of "ends" to start 
from.  What you say MAY make some sense, however, as the first batch of 
boards I did used about half the tray without any bad ones!  Then, the 
second batch I got 50+% bad.  Very curious!

Jon

Jon Elson <elson@wustl.edu> wrote:
...
> Anyway, I have made enormous progress on migrating to Spartan 2E, so I 

Take a plunge and go directly to 3E...

-- 
Uwe Bonnes                bon@elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
--------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------

Jon Elson wrote:
<snip>
> I've never been very successful at opening up Xilinx pacakges.  The 
> epoxy is
> harder than steel (well, at least really abrasive) and I don't have 
> something that will dissolve it.  These are TQFP's, so there's no metal
> lid.  They come in waffle trays, so there are a lot of "ends" to start 
> from.  What you say MAY make some sense, however, as the first batch of 
> boards I did used about half the tray without any bad ones!  Then, the 
> second batch I got 50+% bad.  Very curious!

  Solder the device onto a spare scrap of PCB, and then use a flat 
metalworking  file to remove the plastic. As the covering gets very 
thin, it will lift off the die, so with a little care, you can get quite 
clean exposure of most of the die. Enough to confirm it is 'Xilinx 
inside' :)

-jg

Jon Elson wrote:
> But, I have no other examples of Spartan chips which DON'T have
> the Spartan(tm) marking right below the Xilinx(tm) logo.  That
> was one of the things that made me curious, although I don't
> know why a counterfeiter would miss something that obvious.


This in the news is topical to this thread

"SIA launches fight against fake chips"
http://www.eetasia.com/ART_8800518744_480200_NT_b37a60ac.HTM
" the SIA is fighting on several fronts, including China where huge
stores of fake goods operate freely.

The fake chips are often rebranded parts claiming greater performance
than they actually have to earn the sellers a fast profit. "

-jg