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Date: Wed, 15 Feb 2012 13:29:35 -0500
Message-Id: <201202151829.q1FITZgo006033@envy.delorie.com>
From: DJ Delorie <dj AT delorie DOT com>
To: geda-help AT delorie DOT com
In-reply-to:
	<CAErn8c+C8mBVmqtmcrkZroq-XPa8XgOso3Vv3WOk0miqq_0pTQ AT mail DOT gmail DOT com>
	(message from Luis Emiro Linares on Wed, 15 Feb 2012 11:11:00 -0500)
Subject: Re: [geda-help] How can I route multi-pad signals?
References: <CAErn8c+C8mBVmqtmcrkZroq-XPa8XgOso3Vv3WOk0miqq_0pTQ AT mail DOT gmail DOT com>
Reply-To: geda-help AT delorie DOT com


> 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"