Re: gEDA-user: Clearing mask to mount shields

[Darrell Harmon <dlharmon@xxxxxxxxxxxx>]

On Fri, May 05, 2006 at 12:16:56PM -0400, Dan McMahill wrote:
> Can you create a footprint with some pads that are the right 
> width/length for the shield?  That way if you move the shield around on 
> the board you'll keep all the pieces together.

The board is 160x200 mm and the shield is the same size. There are 
several compartments for different subsystems. The only way I see to
make it work is to draw it in place as it is fairly complex. I assume
I will need to give them all pin numbers (all pin 1) and create a
schematic symbol for the shield plate.

Some kind of mask exclusion layer would be nice in future releases.

> Don't forget, its the largest dimension of a gap, not the area which 
> matters the most.  So if it is a 2 layer board with ground on the 
> bottom, components on top and a can attached to the top, you'll want 
> lots of vias around the edge where the can sits.
> 
> -Dan

The board manufacturer allows up to 2500 vias in a board this size. I
need around 800 for signals, so that should leave me plenty for around
the edge of the shield box. Any ideas on spacing? I have everything
from 500 kHz SMPS noise to a 4 GHz local oscillator. It is a 4 layer
with 18 mils from the ground plane to the top.

-- 
Darrell Harmon
http://dlharmon.com