BGA Socket using 8 mil lines? Wow! That's old technique. Why he's not
using 5/5 on this I don't know, and I'd hate to have to try it. 3.5 mil
annular ring is manufacturable (you can spend the money :), but why? I
wouldn't attempt anything over a 400 pin device with anything larger
than a 6 mil line. And, costs? Not a problem at 5 mils. :)

Good luck.

Mitch Morey
Sr PCB Designer
San Diego, CA
_____________________________________________________________
Tired of limited space on Yahoo and Hotmail?
Free 100 Meg email account available at http://www.dacafe.com