Hi all!

This topic is a "moldy-oldie", but I've started to experience bridges again
with this TI DSP (TMS320C6201GJC200). I've been doing okay up unil recently.
We build these boards in work orders of around 25 pieces.

Our last run we had 7 boards bridged out of 25!! Sent the boards out to be
reworked. I asked that they be x-rayed before and after, and to my surprise
after looking at the x-ray images, they were all bridging in the same general
area.

It's a 4-row periphery BGA, and the bridges are occuring on the inner two
rows, around the center of the part, at the same side of the part.

What's funny, is that the vendor we use to rework the boards for us is having
difficulty as well. We've been asking him to remove, re-ball, and re-install
the part, they said they've been having about a 50% success rate doing
this...they've been getting the bridges too. They have a nice full-blown SRT
BGA rework station and do this for a living.

I print 6-mils of paste (square apertures for the BGA), have a Conceptronic
HVN-70 which I run:

150     160     170     180     240
150     160     170     180     240

25-in. per min

We never have had these problems before...it all started when TI put the
heatsink into the top of the part. I've looked at our paste print and it's
dead on, placement is dead on too, we verify that with a Ersascope.

My question is could there be something wrong with the part? Warping causes
bridges at the corners, right? Why would it bridge in the interior rows at
the same general area?

Thanks in advance!

-Steve Gregory-

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