Heat Management: Don’t Lose Your Cool
Two common causes of heat on printed circuit boards are:
- current passing through passive and small active components, and
- bigger components such as batteries and large semiconductor devices.
Heat generated by these sources raises the temperature and radiates to the surrounding components, heating them up as well.
There are a myriad of ways to approach heat management. The simplest could be to reduce the amount of heat created by your product. Decreasing the voltage, and therefore power consumption, also has been very successful in the past. But, there are other ways to decrease the power output at more of a board versus IC level.
Any power conversion is a great opportunity to find savings in heat and efficiency, such as replacing a low drop-out voltage regulator with a switching regulator. With the shrinking size of electronic gadgets, manufacturers are making smaller and smaller SMDs. However, reducing the physical dimensions of SMDs also reduces their surface area and consequently, limits the heat that can dissipate to the surrounding air. The only way for such components to lose heat is through the solder joints to the copper track holding them to the PCB. You can remove heat from SMDs in three ways:
- Wider Traces: The easiest way to remove heat from components is to provide them with wide traces. Wider copper surfaces also have larger surface area, making them more efficient in dissipating heat to the surrounding air.
- Thicker Traces: When board sizes don’t allow for widening traces, using thicker copper is an option for removing heat from hot components.
- Thermal Vias & Heat Sinks: Designers may also transfer the heat generated to a thick layer of copper or a structure made of copper or aluminum attached to the PCB. The thick layer of copper may be a part of the PCB on its underside and attached to the component track through multiple thermal vias. Be advised these can create assembly issues because solder can thieve through them.
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