A printed circuit board is designed to bring electricity to the component of a device. During this journey through the board, electricity produces heat. Why? Electrical current Is an electron flow through a material called “conductor”. Even though the conductor lets in the current, it also offers different levels of resistance. This resistance is converted into thermal energy. It can also be converted into light energy, as in the filament of a light bulb. Sometimes the heat comes from the component itself. This is the case in lighting devices, processors, power supplies, adapters or electric engines who need to produce a lot of torque.
Heat can be a problem in a system and engineers need to find a solution to control the temperature. Why? The answer could be summed up in one word: reliability. Many components are made with silicon and overheating is destructive for this material. The optimum temperature is defined by the suppliers. An increase of 20 ° C reduces the life of the component by 50%. As a result, the service life of the device, which affects reliability, raises warranty issues and ultimately reduces the benefits to the manufacturer. Having a fault on a device is not a good thing for anyone and that is why the temperature needs to be controlled.
How to keep the temperature under control?
Increasing the gaps between the lines of a PCB can be a good option for controlling heat in the circuit. But the market trend is to reduce the size of the devices, miniaturize the components, the size of the boards, etc. This solution is not often easy to use in the current trend.
A heat sink is attached to the board or component and provides high heat dissipation. The metal removes heat from the circuit and gives a larger area of contact with the environment (fins) to transfer heat.
Thermal Vias are drilled under the component through the board. Vias, which can be plated and not plated, brings fresh air and evacuates heat. Plated vias are more efficient because copper can accumulate more heat.
Copper inlay are large pieces of copper placed inside the vias. This copper mass keeps the temperature down longer because the more mass, the longer it takes to heat. For example, a small pot of water will take less time to boil than a large one. The copper inlay also acts as a radiator and gives more surface contact with the local environment. Copper can also be buried inside the board. This is called embedded copper.
In some complex systems, such as powerful servers or computers, engineers can use a liquid-cooled circuit that works just like an automotive cooling system. The fluid circulates in a closed circuit, removes heat from the board and is cooled in a radiator in contact with a fan or at room temperature.
Most PCBs are made for low voltage or low power application, but the need for high power devices is growing. Heavy Copper technology is designed to increase current carrying capacity, temperature resistance, reduced products size without the risk of failure. When standard PCBs have traces of copper thickness ranging from ½ oz/ft2 to 3 oz/ft2, Heavy Copper may have traces of up to 20 oz/ft2.