I am using the ZWT package . (S-PBGA-N361) I have been researching the best footprint but have encountered conflicting information.
In the some forum discussions a .4 mm pad was recomended because the ball diameter is .5 mm. However your literature, (SSZA002A) recomends a pad size based on the package side pad size, not the ball diameter. Also that literature recomends a maximum size pad of .4 mm yet the package I am using ZWT, does not appear in the literature. I was confussed and so went looking for a mechanical drawing of the package. I cannot find a drawing that provides the package pad size.
So i downloaded the footprint suggested for the package, TMS320C6748_ZWT_361.bxl. I thought I was in good shape, but that footprint has .432 mm pads. This leaves very little room for vias. What is going on?
Can you help clear this up?
Thanks
Ralph Longton
LoJack Corp