Re: gEDA-user: pcb: Track routing strategies and tips

[Andrew Poelstra <asp11@xxxxxx>]

On Tue, May 10, 2011 at 04:26:06PM -0700, Colin D Bennett wrote:
> As a rather inexperienced PCB designer, I find that I have to throw
> away two or three layouts until I get one that is usable--and still
> not entirely satisfactory.  I always end up with such a mess of traces
> that I know I need better organization and a method to the madness.
> But I am a newb with little knowledge so I fall back on trial-and-error.
> 
> Does anyone have any tips on how to plan a layout for easy and clean
> track routing?  In particular for 2-layer boards.
>

As a hobbyist, I work mainly with 2-layer boards, since those are what
I can make at home. This means that I also minimize the number of vias
I use, which presents its own challenges. My latest pcb is here:

http://wpsoftware.net/andrew/stereo_bike.pcb

This was also interesting because I was space-constrained (the board
needs to fit into a small cast iron box on my bicycle) and since this
is a high-powered audio application, I needed large power traces and
a lot of heat sink.

As has been said, experience is a huge factor in laying out boards.
Don't be afraid to rotate things 180 and try odd ways of connecting
components. Using source control on PCBs is a good idea.

Do things locally (in my case, the power supply, main amp and guitar
pre-amp were all laid out separately) and worry about connecting them
later. Figure out how to avoid intersections before spacing things
out.

If you get stuck, it can help to decide ``I'll just use a jumper wire
here'' and move on. Often problems are easier to solve once more of
the board is in place.

> One strategy that I have seen and recently tried is to use the top
> layer for all horizontal trace runs and the bottom layer for all
> vertical trace runs, or vice-versa.
> 
> Do you ever use the pcb autorouter or do you always route by hand?
> 

The autorouter uses too much space in my experience and isn't good
at deciding what trace widths to use.

> Do you ever study other people's PCB designs to learn from them?  I
> think you could find both good and bad examples: things to emulate and
> things to avoid yourself.
> 

Yes :) fortunately, in my line of work I am also often able to ask
the designers of said boards what they were thinking.

> Thanks for any suggestions.  There are some incredibly experienced and
> talented electronic designers on the list and I'd love to learn
> anything I can from you all.
> 

-- 
Andrew Poelstra
Email: asp11 at sfu.ca OR apoelstra at wpsoftware.net
Web:   http://www.wpsoftware.net/andrew/



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