Definition
A copper pour is a large filled region of copper on a printed circuit board layer, as opposed to a narrow trace. Pours are most often assigned to a ground or power net, where the wide conductive area lowers impedance, carries heavy current, and helps spread heat away from hot components. When an entire layer is dedicated to one net the result is usually called a plane; a pour that simply fills the empty space around traces on a routing layer is sometimes called a polygon pour.
Why pours matter
A solid ground plane gives high-frequency return currents a direct, low-impedance path beneath their signal traces, which reduces electromagnetic interference and noise. The large copper area also acts as a heat spreader, which is valuable on power-dense boards. On an ASIC hashboard, broad copper pours distribute the high currents that feed the chip domains and conduct waste heat toward the heatsink and airflow path.
Pours and via stitching
A pour is only useful when properly tied to its net. Isolated copper islands left floating can actually create interference rather than suppress it, so a good design connects every patch of a ground pour back to the main plane with multiple vias, a practice called via stitching. For a repairer, a copper pour is a generous, low-resistance place to anchor a ground jumper, though its large thermal mass means it sinks heat quickly and demands a hotter iron or more soak time to solder to. Pours interact closely with the PCB stackup, which sets how planes are arranged across the layers.
In Simple Terms
A copper pour is a large filled region of copper on a printed circuit board layer, as opposed to a narrow trace. Pours are most…