I have two scenarios, and in both I need to allow placement of parts under an IC.

1) I need to place pads for optional 0 ohm resistors under an IC. These resistors may be used instead of the IC.

2) I am working with a DIP-style board. Possibly because I have used a DIP IC as the starting point for my small board, the autoplacement and autorouter do not work because there seems to be a "keep out" on the top side of any IC outline.

Is there such a thing as a keepout area, and where can I modify / remove it on an individual (IC by IC) basis?


Resolution:
I was mistaken to think that the autorouter DOES NOT route any traces under the top part because my top layer was turned off in the Shape Router Setup!

There are no keepouts on standard DIP patterns. But autoplacement can't place small components under big one (on the same or opposite sides).

Can I go around that by free-drawing two columns of pins / pads instead of using a two-sided or four-sided IC or a pre-existing library pattern?

After I manually place smaller ICs under larger ones, would this cause any problems with the auto-router?

What you might have to do is create a "hybrid" component & pattern.

That is, if you've got a DIP-20 pattern with 2 rows of 10 pins then you could add more pins in between these parallel rows and they could be routed in the PCB tool (you are then free to mount whatever you like on these new pins). Obviously the pattern as a whole would be auto-placed if you're using the autoplacement function, so you would need to be mindful of that.