Trace width tolerance table

[Sajal_ee]

I found trace width tolerance table in the ebook. I have seen in microelectronics boards that they use 1/2 oz and 1 oz copper layers.

How about using 1 oz in power and ground planes as 1 oz can carry more current then 1/2 oz. And in signal layers we use 1/2 oz as we can have 4 mil and 3 mil trace in outer and inner layers as minimum according to the table. Any comments on this please ?

[atar.mittal]

Generally speaking, you have to go with the loosest tolerance. But you should check with your PCB house if they can fabricate it.