PCB Heat Transfer

Printed circuit boards (PCBs) generate heat as they operate. To prevent heat damage, you need the right heat flow techniques to ensure this energy dissipates.

Basics of Heat Transfer

At a basic level, a discussion about heat transfer includes two topics: temperature and heat flow. Temperature represents the level of thermal energy that’s available, while heat flow represents thermal energy moves from one place to another.

Microscopically, thermal energy is directly related to a molecule’s kinetic energy. The greater the temperature of a material, the greater the thermal agitation of its molecules. It’s normal for areas that contain a lot of kinetic energy to pass it along to areas with less kinetic energy.

There are some material properties that effectively modulate heat that’s transferred between two areas at different temperatures. These include thermal conductivities, material densities, fluid velocities and fluid viscosities. Together, these properties make resolving many heat transfer problems pretty complicated.

The Mechanisms of Heat Transfer

Heat transfer mechanisms can be grouped into three broad categories:

Conduction. Areas that have more molecular kinetic energy will send their thermal energy to areas that have less molecular energy. This occurs through a direct collision of molecules, known as conduction. In metals, some of the energy transported from one area to another is also carried by conduction-band electrons.

Convection. When heat is generated in an electronic device, it’s transported via conduction to an area

where it is then transferred to a fluid. That process is convection, and the fluid can take the form of a gas such as air or conventional water.

Radiation. All materials give off thermal energy in amounts that are determined by temperature. When the temperatures are uniform, the radiation flux is in equilibrium between objects, and there is no exchange of thermal energy. This balance changes when temperatures vary and thermal energy is transported from areas of higher temperatures to those of lower temperatures.

PCB Design Techniques for Heat Transfer

When it comes to heat management in PCBs, you can use a few techniques. Your options include:

  • Heat sinks. This technique uses large metallic pieces with high conductivity. These pieces attach to parts that produce heat and expose more surface area to the air. This setup lowers thermal resistance, and with a cooling fan, you enhance heat flow further.
  • Copper pours. When you fill unused areas with metal and ground the metal, any component in the PCB will connect to the ground with ease.
  • Thermal vias. Often used with copper pours, thermal vias create a pathway to the copper and the PCB components.
  • Copper Filled vias. vias can be filled with copper to improve the heat transfer.
  • Higher Thermal Conductivity Materials. Materials like Aluminum; Ceramics; and Copper core are used to improve the thermal conductivity of the PCB.

When you encourage steady heat flow in your PCB, you can expect efficient electrical performance and a long lifespan.

Contact Millennium Circuits Limited for PCB Construction

Millennium Circuits Limited supplies high-performance PCBs to engineers. Regardless of your industry, our PCB selection ensures your devices have an excellent foundation for reliability and functionality. If you’d like to learn more about our products, contact us today.