Heat sinks dissipate heat primarily through three modes of heat transfer: conduction, convection, and radiation.

 

Radiation: Refers to thermal energy dissipating from a heat source in the form of electromagnetic waves (carried by photons). Radiation can occur even in a vacuum. The efficiency of radiation heat transfer depends on the material of the heat source and the surface color.

 

Conduction: Involves the exchange of kinetic energy between molecules, where lower energy particles gain energy from higher energy particles through direct physical contact. Conduction is the primary method by which heat sinks absorb heat from the CPU.

 

Convection: Involves heat transfer through the movement of a heated substance (typically a gas or liquid). This means heat originates from a heat source surrounded by gas or liquid, and heat energy is transferred through molecular movement. Adding a fan to a Heat Sink facilitates forced convection.

 

The thermal dissipation principle of heat sinks utilizes these three methods. Generally, maximizing the surface area of a heat sink enhances airflow. Using metal fins not only increases surface area but also improves the efficiency of convection. It's crucial for the contact surface between the heat sink and CPU to be smooth; otherwise, an insulating layer may form, reducing thermal conductivity. Thermal paste, thermal grease, or specialized pads can be used to improve contact and increase the contact area.