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Date: Fri, 17 Feb 2012 11:16:16 -0500
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Subject: Re: [geda-help] How can I route multi-pad signals?
From: Luis Emiro Linares <macgyveremir AT gmail DOT com>
To: geda-help AT delorie DOT com
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Thanks for your advice. The chip is the FDMF6707 DrMOS module from
Fairchild. I'm doing the PCB footprint and the gschem symbol. I have
now the following questions:

1. Could you please elaborate on how, if the pads have different pin
numbers, the autorouter will know?
2. For the gschem symbol, Is it valid for me to define a multi-pad
signal (i.e. PGND) by setting its pinseq and pinnumber both equal to a
comma-separated list of the pad numbers to which it corresponds in the
footprint?

On Wed, Feb 15, 2012 at 1:29 PM, DJ Delorie <dj AT delorie DOT com> wrote:
>
>> I have made the footprint of a 40-pad QFN chip + 3 hidden pads
>> underneath. There are 6 signals that are to be connected to several
>> of the pads, both on the border and underneath the package. Is it
>> possible to instruct the PCB autorouter about this multiple
>> connections?
>
> In general, if the pads have different pin *numbers* [*] the autorouter
> will know that they all need to be connected.
>
> However, I've found that it's often better to hand-route the traces
> *under* the chip first, and let the autorouter take care of the rest.
> Likewise, the autorouter isn't that smart about power/ground nets,
> since they usually have different rules than regular signals.  I do
> all my bypass caps and power/ground planes first, fan out any
> problematic pins, then see how the autorouter does.
>
> For more specific help, you'll need to tell us which chip it is :-)
>
>
> [*] i.e. same label, different pins, vs overlapping pins/pads with the
>    same number forming one oddly-shaped "pin"



-- 

Luis Emiro Linares García
------------------------------
Físico - Ingeniero Electrónico
Universidad de los Andes
Bogotá D.C., Colombia.