Homebrew PCBs

On Thu, 18 Jan 2007 21:29:59 +0100, David McNab <rebirth@...>  
wrote:

> Hi,
> What do people see as the pros/cons of copper pours in board artwork?
> For mainly digital circuits with small amounts of analog sampling, do
> they offer any significant improvement in electrical performance?
> I tried a couple of boards with GND copper pour.
> For me, all I've noticed is that they make my etchant last a little
> longer, but increase the time taken in removing backing paper, and make
> the soldering phase slightly less comfortable.
> Cheers
> David

Ground planes are a huge topic, i suggest you google and read some of the  
papers (often from IC manufacturers).

There are many potential problems, especially with our one and two layer  
boards where copper areas will be badly connected or even isolated  
alltogether. For high frequencies an island grounded by only one spot may  
be more of an antenna than anything else, and should be grounded at least  
on the far end through vias.

The more obvious problems are of course capacitive coupling to ground, and  
ground drops, although vastly reduced, may add up in different ways than  
without the copper pour. completely isolated areas are even more  
problematic, potentially coupling unwanted signals together.

Anyway, i don't understand half of it, but read the stuff on the web,  
lotsa stuff going on with ground planes that you may not expect.

ST