counterfeit Xilinx ?

Some ideas: Did you bake the parts before assembly? Are you hand-soldering the deviecs?

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

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

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 wrote: ...

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

-- Uwe Bonnes snipped-for-privacy@elektron.ikp.physik.tu-darmstadt.de

Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt

--------- Tel. 06151 162516 -------- Fax. 06151 164321 ----------

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

This in the news is topical to this thread

"SIA launches fight against fake chips"

" 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