Re: [SI-LIST] : GND on the outer layers

Douglas McKean (dmckean@corp.auspex.com)
Wed, 14 Jul 1999 16:33:06 -0700

At 03:04 PM 7/14/99 -0500, Bill Dempsey wrote:
>
>Doug,
>
> How do you address pads & pin escapes with this stackup?
>Are you in fact assuming a 10 layer board? Or did you intend
>to flood areas of the top and bot with gnd? The flooding method isn't
>nearly as robust as your previous (3db only) stackup.

The board was not of high enough density to
really worry escapes. Yes, flooding or pouring
or filling as I think it's called also.

>You could alleviate the problem, add xtalk isolation, and no cost
>change by restacking as follows:
>
>signal
>gnd
>signal
>gnd
>pwr
>signal
>gnd
>signal
>
>This also allows x&y routing on internal layers (by avoiding parallelism
>rules). It may prove to be easier to route because of that (not
>guaranteed).

The stackup was stuck at 6 layers.
The 8 layer stack up which wasn't allowed.

Regards, Doug McKean

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