A region of solid copper on a layer, tied to a net (usually GND). Replaces individual GND traces; every GND pad connects through the surrounding copper. Standard practice.
How it looks
Real geometry: CORE3588 copper, drawn from our board file (2D plan view)
Top copper of CORE3588, whole board. Amber is the ground pour GND_PLANE_TOP, plus every ground pad and via. It fills all the space the tracks and pads leave free.
Real geometry: CORE3588 copper, drawn from our board file (2D plan view)
Zoom: 8 x 6 mm. The pour flows around grey copper of other nets, keeping the clearance gap (dark outline) everywhere.
How it works
Where it fits
A pour that covers a whole layer is a ground plane. Where a pad sits in a pour it can join solid or through a thermal relief.
On CORE3588 every copper layer has a GND pour; there are also small pours for power (PERIPH_3V3, CAM_3V3, SD_3V3).