Here’s an annoying problem. I’ve done an FreeRoute autoroute on a layout with a copper pour zone. Some pads aren’t connected to ground. The autorouter is happy, with no incompletes.
Unconnected ground pads. Note especially W1, with a trace to nowhere. Also note the rat’s nest lines indicating unconnected GND pads.
There’s a pour zone that begins near the end of the vertical trace from W1. Parts of it are filled, and parts are not. The problem is that the autorouter assumes that everything in the copper pour zone is connected to ground. But there are areas of the pour zone that DRC doesn’t fill, because they don’t have a path to a ground pad. The result is as shown, with pads that don’t connect.
DRC catches this as an error. But how to fix it?
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The polygonal zone in the kicad layout will have an associated net, so anything touching it will be electrically connected to that net, as far as the autorouter is concerned.
I don’t think the autorouter is clever enough to deal with isolated islands within the polygon created during track creation, which is another level of difficulty over and above the topological routing task.
What happens if you autoroute without the polygonal zone, and then create your copper pour afterwards?
I usually do the pour last, after I’m happy with all the other routing and component placement.
Regards,
Erich
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Pour after autoroute does work. DRC is smart enough to generate a pour that doesn’t have unconnected areas.
A note on this. Before running the autorouter, pour zones have to be disabled by setting them to “no net”. Otherwise, the autorouter assumes they are fully connected, and you can have several different sections of pour that are not connected to each other. After autorouting, zones can be reset to their proper nets. Then rerun DRC to clean things up.
Is there some easier way to do this?
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