[Oap-discuss] PCB run (too many layers)

[<sco...@mi...>]

Hi Dafydd,

1. I've requested that PWT provide three units of a four layer layout. 
I would be happy to share one with you.  The cost is  $59 / unit 
with shipping.

2. I'm not certain about the Excellon drill plot output, but PWT 
www.pwtpcbs.co.uk were able to import the Gerber output from PCB.

3.  I agree that the number of layers can be reduced.
 I'd would very much like to try to simplify it as we look ahead.  
Do you have an idea of what the cost impact might be?  I noticed
that the motor driver module boards are at $12 / unit - but I 
presume that this a full production run.

4.  The feedback on trace width is also very helpful.  Thanks!  
I would like to point out that I set the trace size to 15 thou and 
then instructed PCB to automatically layout all of the traces.  
It's an impressive tool, and replaced what would have been
 a rather tedious process.   The downside is that it generated
four copper layers!

5.  Thanks again for looking over the layout!  I'll keep my fingers 
crossed...

Regards,
Scott Crawford


*********

If you're going to have a run of prototype PCBs made, I'd be happy to
share the cost with you in return for one of the PCBs, if you like.
Perhaps some other people on the list would also be interested in doing
this too, if your run is going to be for several boards.



Have you figured out how to export Gerber photoplot files, and the
Excellon drill plot?

Do you intend to have prototypes made with all 4 Gerber layers (i.e. top
and bottom copper, silk screen and solder mask), or are you just going for
two?

Dafydd.



--__--__--

Message: 2
Date: Tue, 20 Jan 2004 10:14:43 -0000 (GMT)
From: "Dafydd Walters" <dwa...@us...>
To: oap...@li...
Reply-To: dwa...@us...
Subject: [Oap-discuss] MCM PCB - too many layers!

Scott,

> Please see the following URL for a picture of the motor control
> module PCB layout.
>
> http://www.mindspring.com/~scottcrawford/mcm.png

I've just noticed that you appear to have designed this as a 4
copper-layer board! This is definitely overkill for such a simple circuit,
and will make the board unnecessarily expensive. Two copper layers
(component and solder side, i.e. top and bottom) are quite enough for this
circuit.

Looking at the layout, I don't think it would be too difficult for you to
turn this into a two copper-layer design; you just might have to move some
traces and add a few more vias, though. If you do change the layout, you
might also consider making all the power traces wider (double or triple
the current width where possible). In my experience, it's generally a good
idea to make all traces farily wide anyway, layout permitting. I often use
20 thou for signal traces generally, and just narrow them down to 10 thou
when necessary (e.g. to get between the legs of a component), and I use 30
thou or wider for power rails.

Regards,
Dafydd.




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