4.4. Automatically route with FreeRouter

Routing a board by hand is quick and fun, however, for a board with lots of components you might want to use an autorouter. Remember that you should first route critical traces by hand and then set the autorouter to do the boring bits. Its work will only account for the unrouted traces. The autorouter we will use here is FreeRouter from freerouting.net.

1. FreeRouter has some features that KiCad does not currently have, both for manual routing and for automatic routing. FreeRouter operates in two main steps: first, routing the board and then optimising it. Full optimisation can take a long time, however you can stop it at any time need be.

2. You can start the automatic routing by clicking on the Autorouter button on the top bar. The bottom bar gives you information about the on-going routing process. If the Pass count gets above 30, your board probably can not be autorouted with this router. Spread your components out more or rotate them better and try again. The goal in rotation and position of parts is to lower the number of crossed airlines in the ratsnest.
3. Click on the File → Export Specctra Session File menu and save the board file with the .ses extension. You do not really need to save the FreeRouter rules file.
4. Back to Pcbnew. You can import your freshly routed board by clicking on the link Tools → FreeRoute and then on the icon Back Import the Spectra Session (.ses) File and selecting your .ses file.