What is Heat Sink
The heat sink (also spelled as heatsink) is a passive heat exchanger that transmits the heat produced by the mechanical or electrical device to a liquid (usually coolant or air) where the heat dissipates away from the device. This allows you to regulate the temperature of the device. The heat sink completes this process by increasing the working surface area of the device and the amount of low-temperature fluid that flows through the extended surface area.
The heat sink is constructed of good thermal conducting material. Most commonly it connects to an electronic device to expel the unnecessary heat.
The working of the heatsink is based on Fourier’s law of thermodynamics. According to this law, when the object has a temperature gradient, heat is transferred from the hot component to the cold region.
There are three different methods of heat transfer that are conduction, convection, or radiation.
Conduction process takes place when two objects at different temperatures come into contact. This includes collision between the slow moving molecules of the cold object to the fast molecules of the hot object. Due to the temperature difference, the heat transfers from the hot to the cold object.
Therefore, heat sinks transfer heat from hot components (like transistor), to cold media (such as water, oil, air) or through conduction and then convection process.
Types of Heat Sinks
1) Active Heat Sink
If the heatsink uses a fan (HSF), it is an active heatsink. On most computer processors, the fan is mounted directly above the heatsink. It uses electricity for the cooling process.
Active radiators are used in liquid cooling systems. These are basically heat sinks with a structure on top that significantly increases the available surface area for dissipating heat to the surrounding air. They are more efficient than heatsinks, but more expensive to manufacture and take up more space.
2) Passive Heat Sink
If the heatsink does not use a fan, it is a passive heatsink. It is very reliable as there are no mechanical parts. These heatsinks are made of finned aluminum heatsinks. They dissipate heat using the principle of convection. Sufficient and stable airflow is maintained between the ribs to ensure the stability of the device.
This includes radiators, which rely on fluid pumping to remove latent heat from heat sources. Active heatsinks are more efficient because they rely on forcing air through the fin area. That means a smaller and lighter heatsink design.