Top 7 PCB Heat Transfer Techniques Discussed

Top 7 PCB Heat Transfer Techniques Discussed

Miniaturization is in trend for several years. Most advanced electronic equipment that we use today features compact-sized and high power components like high-power LEDs, high-performance processors, MOSFETS, and so on. The size and power transfer capabilities of these components has been widely appreciated; however, the downside is the high heat generated by them. Although most PCBs are designed to withstand a certain amount of heat, some components may fail if exposed to high temperatures for a long time. This would lead to device failure. To avoid this, various thermal management techniques are employed. This post discusses these PCB heat transfer techniques and thermal modelling in brief.

What is Thermal Modelling and How It Helps in Effective Thermal Management?

Thermal engineers and electronic equipment designers always perform thermal modeling to address thermal issues that PCBs may develop during the operation. This is performed using various software applications. The software helps them understand the accurate positioning of components for efficient thermal management. During the thermal modeling, the product designer decides upon the maximum acceptable component temperature and examines how these temperatures change based on power dissipation. Based on the analysis, the designer can effectively address different aspects such as choosing effective cooling methods such as fans, incorporating heat sinks, thermal vias, additional copper traces, etc.

Seven Effective Techniques of PCB Heat Transfer Discussed

The PCB designers use several effective PCB heat transfer techniques for effective thermal management of components. The following are seven such techniques that have gained popularity.

• Positioning of High Power Components: Most commercial and industrial electronics equipment features high-performance PCBs. Further, these PCBs are equipped with high-power components such as microcontrollers and processors. As per best practices of thermal modeling and PCB design, these components must be placed in the center for better heat dissipation. By doing so, the heat produced by the components will be equally distributed in all directions. This will help manage the surface temperature of the PCB effectively. If a PCB design involves several high-power components, ensure to maintain appropriate spacing between them. They must be placed evenly across the board to avoid complexities. Also, high-power components must be placed away from sensitive devices.
• Copper Trace Widths: The width of copper pads or traces plays an important role in thermal management. Generally, thick copper traces are considered because they offer larger surface area for heat dissipation. Thick copper traces are usually preferred for high-power PCBs.
• Use Thermal Vias: Vias are holes that penetrate to the other side of the PCB. Thus, it can be rightly said that thermal vias help conduct heat through the hole to the other side of the board, where it dissipates naturally. Often thermal vias are placed closer to the surface mount devices or SMDs on the PCB. The designers generally define the number of thermal vias on the PCB based on the surface area and heat dissipation range. The standard dimensions of thermal vias are 12 mil or 0.33mm on 0.44mm grid spacing. No via filling is added.
• Use Heat Sinks and Cooling Fans: The heat sinks are thermally conductive metal parts or fins attached to high power components such as switching devices and transistors to draw away heat. These heat sinks facilitate heat transfer over a large area. They work on the principle of conduction, where the heat is transferred from the high thermal resistance area to the low area. Although heat sinks have been one of the most effective methods of PCB heat transfer, designers choose based on factors such as the cooling fluid velocity, number of fins and spacing required between them, and the thermal resistivity of the sink material used, etc.
• Use Thick PCBs: If the PCBs are designed for small devices, then most cooling methods discussed here wouldn’t work. This is where thicker PCBs can help. The PCBs offer a large surface area for heat dissipation and allow effective thermal management.
• Use Heat Pipes: They are more appropriate for the printed circuit boards to be used in constrained spaces or the printed circuit boards used in high-temperature applications such as avionics, satellites, and so on. As the name suggests, the heat pipes look like regular pipes with cylindrical structure, but are much smaller in configuration. The heat pipes feature liquid, which captures heat dissipated by different PCB components. This heat helps vaporize the liquid, which condensates on the condenser end. The vaporized liquid is then returned to the evaporator through tiny wick structures. This process ensures the heat is properly dissipated from the PCB. Liquid metals and cryogens are two popular types of pipe fluids used. The choice of the right fluid depends on different factors, including the circuit’s temperature range, chemical compatibility of the fluid with the container, and the wick material and so on.
• Use Cooling Fans: The cooling fans are more effective methods of PCB heat transfer. Unlike the other techniques discussed here, the cooling fans ensure convective heat transfer. The fan pushes the heat away from the device and designers have to make several considerations before choosing the right fan.

The PCB heat transfer must be addressed carefully and most experienced manufacturers incorporate it during the design and assembly stages. Hence, when choosing the PCB assembly service, ensure to get it done from a manufacturer experienced in serving OEMs of commercial and industrial electronics. Twisted Traces is one of the PCB assembly services in the USA with vast experience of serving industrial and commercial electronics OEMs to their credit. The company takes pride in its list of clients from military and defense, consumer electronics, and LED PCBs. Having worked with them, the company understands the complex design requirements and conducts thermal modeling efficiently. You can get in touch with the experts at the company to discuss your requirements.