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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