Keepout

A keepout (also called a keep-out, or a blockage) is a drawn region that tells tools and people not to place a stated kind of object there.

The strap stops at the edge of the region. It does not enter.

Space that looks empty is not always free to use. A keepout drawn over an inductor bans fill. A keepout near a waveguide bans dummy metal. A keepout on a board bans traces under a tall connector. The mark is a layer, and the tools honor it when the name matches the one they expect. On screen it may be a hatched rectangle around a coil, or a polygon inside a footprint that says "no copper." A 200 micrometer halo around a MEMS membrane is a typical keepout. The same drawing protects a probe pad, a MEMS cavity, or a region the package glue will cover. A 150 micrometer keepout under a QFN paddle keeps a via-in-pad out of that glue.

A courtyard is the board cousin that reserves room for a part's body. Clearance is a distance rule rather than a drawn region, though the two words get blurred in conversation. DRC may check that real geometry stays outside the keepout. A hatch placed on a documentation layer is a picture the router ignores. The blockage has to sit on the layer the PDK, or the board stack, expects. Name that layer in the handoff. Otherwise the next engineer treats the hatch as decoration and pours copper through it.

See design rules and DRC, footprints are almost cells, and a PCB stackup.