Definition

Thermal relief is a spoke pattern (typically 4 spokes) connecting a through-hole or via pad to a surrounding copper plane. Without thermal relief, the plane acts as a massive heat sink, making hand soldering nearly impossible and causing cold joints in wave soldering. The spokes provide electrical connection while limiting heat transfer. Spoke width affects current capacity - wider spokes for power connections. Some high-current applications eliminate thermal relief entirely (direct connect) and rely on reflow or controlled soldering processes. Thermal relief design balances electrical performance against manufacturing requirements.