Thermal performance is a key issue in function of a circuit board, heat generated by integrated circuits, flowing currents in long tracks and power loss in power ICs can cause the board/device temperature rise. The high temperature can cause failure of some electronic components and make the board malfunction.
In an ideal design, we want the entire PCB is at the same temperature and in a safe area. To be able to make a PCB operate in a safe temperature there are many factors to consider;
- track widths
- copper thickness
- number of layers used
- continuity of thermal paths
- the size of thermal reliefs(*)
- the area used for heat transfer to the atmosphere
- usage of heat sinks
- board area
are some of the most important ones.
To reduce the temperature of the board make sure that heat sources are directly connected to large copper areas like ground planes with multiple and if possible large vias, keep high current paths short and wide, use copper areas and copper pours as mush as possible.
(*)Thermal relief pad is a printed circuit board pad connected to a copper pour using a thermal connection, ie narrow spokes. If you connect a pad to copper pours or plane layers with wide spokes or directly it will transfer heat perfectly but at the same time it will make soldering very hard and desoldering nearly impossible without a very powerful heat source.