What is meant by a thermal pad?

FAQ about printed circuit boardsTERMINOLOGY

For SMD components, especially the smaller ones, use thermal relief pads to simulate the same thermal mass on both terminations to avoid tombstoning, twisted components or even in worst case broken components.

Close-up of a thermal pad
Close-up of a thermal pad

For hole mounted (HMD) components we use thermal relief pads on inner layer planes to help wetting in the hole barrel. Formulas for thermal relief pads can be found in IPC-2220 series.

Close-up of a thermal pad