Pat,

Personal opinion:  Don't use guard bands.  Keep the spacings
around all the associated traces AS IF you were using guard
bands, just don't put the guard bands in the board.

The effect will be the same - good seperation of circuits
and lower crosstalk.

Regards,  Doug

Pat Paulson wrote:
>
> First I want to say thanks for all the replies about BGA routing. I finally
> decided against all pin escapes at the part. This makes life much easier.
>
> Next question is concerning special considerations for clock signals and
> EMI.  Some of the Engineers want a ground trace surrounding the clock lines
> and others say it would be better to just leave the space around the clock
> line that the guard band would normally take up. The clock speeds are 40
> Mhz and below using 6/6 on the inners and 8/8 on the outers. One of the 2
> clock routing layers is next to the ground plane and the other layer is
> next to the power plane.
>
> All info is greatly appreciated!

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