Why are my S3A pins getting destroyed?

I have a S350A VQFP100 on my custom board, with all
the pins connected to large pads all around the chip.

I have destroyed 3 pins, total.
Two pins can't be used as inputs anymore,
and the third lost tri-state ability.
BTW, the pins are in two VCC banks.

True, my soldering tip is not grounded,
but the last pin was destroyed a few days ago,
and I didn't physically touched the pad it is
connected to for at least 3 months.

First two pads I did touch a lot with my soldering tip
while testing, so I can believe that it was destroyed
by ESD. At that time, I have also soldering 10 other pads
near those two, but they didn't die.

But what about that third pin?
It is a part of the data bus (D2), located in top bank,
and it hasn't been touched by soldering tip or even the
scope for at least 3 months.

So, why did it die?

 

Damn it, I've found the error, the wire is badly soldered.

 

[Tim Wescott]

On Fri, 23 Mar 2012 14:02:54 -0700, aleksazr wrote:

Damn it, I've found the error, the wire is badly soldered.

And fixing one wire is worse than having to replace a whole FPGA?

--
My liberal friends think I'm a conservative kook.
My conservative friends think I'm a liberal kook.
Why am I not happy that they have found common ground?

Tim Wescott, Communications, Control, Circuits & Software
http://www.wescottdesign.com