Thermal Management of Modern PCBs: How to Manage Heat Effectively

Modern electronic devices are becoming smaller, more powerful and increasingly packed with electronic components. As performance increases, so does the amount of heat generated during operation. This is why thermal management of PCBs is becoming an increasingly important part of modern printed circuit board design.

While heat dissipation can be relatively straightforward in simpler electronic devices, it can become one of the major design challenges in high-performance processors, automotive electronics, telecommunications equipment and AI servers. Heat therefore needs to be considered already during the PCB design stage rather than after the board has been manufactured.

Why Is Thermal Management of PCBs Important?

Every electronic component generates a certain amount of heat during operation. For standard components, the amount may not be significant, but processors, power transistors, voltage regulators, converters and power amplifiers can generate a substantial thermal load.
If heat is not dissipated sufficiently, it can lead to:

• overheating of electronic components,
• reduced component lifetime,
• changes in electrical properties,
• device instability,
• component damage,
• reduced long-term reliability of the entire device.

However, maximum operating temperature is not the only factor that matters. Repeated heating and cooling also play an important role. Differences in the thermal expansion of materials can create mechanical stress in the PCB, solder joints and vias during thermal cycling.

Where Is Most Heat Generated on a PCB?

As part of thermal management of PCBs, it is first necessary to identify the main sources of heat.
These typically include:

• processors and GPUs,
• power transistors,
• voltage regulators,
• DC/DC converters,
• power amplifiers,
• LEDs,
• power resistors,
• high-current connectors.

The positioning of these components is also very important. If several high-power components are located close to each other, a hotspot – a locally overheated area – can develop in that part of the PCB.
It is therefore not enough to monitor only the average temperature of the entire board. During PCB design, it is also necessary to consider heat distribution and identify areas with the highest thermal load.

Copper – an Important Part of PCB Thermal Management

Copper performs two important functions in a PCB. It conducts electrical current and also helps transfer and distribute heat.
A larger copper area allows heat to spread over a larger part of the board. In power applications, designers can therefore use larger copper areas, power and ground planes, or thicker copper layers.
The thermal and electrical properties of conductors are also closely related. The IPC-2152 standard addresses the relationship between conductor current-carrying capacity and temperature rise.
Factors such as conductor width and thickness, the amount of copper, the board construction and other conditions all affect the resulting thermal behaviour.
In high-current applications, electrical connections therefore cannot be designed separately from the thermal aspects of the PCB.

Thermal Vias Help Dissipate Heat

One of the most commonly used methods for transferring heat through a PCB is thermal vias, which play an important role in the thermal management of PCBs.

Thermal vias are often placed directly underneath a power component or in its immediate vicinity. They transfer heat from the surface layer to internal copper layers or to the bottom side of the PCB.

A properly designed array of thermal vias can improve thermal management of PCBs by:

• transferring heat away from the component,
• distributing heat across a larger copper area,
• thermally connecting multiple PCB layers,
• improving the connection to a heatsink or another thermally conductive structure.

Thermal vias are particularly important in modern densely populated PCBs, where space for conventional cooling methods is very limited. Properly designed thermal vias can therefore contribute significantly to effective thermal management of PCBs and help prevent local overheating.

PCB Material Affects Heat Dissipation

Material selection also plays an important role. Standard FR-4 is suitable for a wide range of applications, but it may not always be the optimal solution for electronics with a high thermal load.

Depending on the application, designers can consider:

• materials with higher temperature resistance,
• metal-core PCBs,
• ceramic substrates,
• materials with higher thermal conductivity.

Ceramic boards based on aluminium oxide or aluminium nitride can be suitable for applications where efficient heat dissipation is one of the main requirements.

However, material selection cannot be based solely on thermal conductivity. Electrical properties, mechanical requirements, manufacturing technology, cost and expected operating conditions must also be taken into account.

PCB Layer Count and Construction for Better Thermal Management

In multilayer PCBs, thermal management of PCBs is also strongly influenced by the overall board construction and its stackup.

Internal copper layers can be used not only for signal and power distribution but also for heat spreading, making them an important part of thermal management of PCBs. Thermal vias can connect individual copper areas and create a more efficient path for heat dissipation. This is becoming increasingly important for highly complex PCBs with a high number of layers.

A typical example is PCBs used in AI servers. Increasing computing power is leading to higher interconnect density, higher layer counts and greater requirements for both power distribution and heat dissipation. In the context of AI servers, PCB designers and manufacturers increasingly discuss high layer counts, HDI technology and thermal via arrays as important elements of advanced server PCB design and thermal management of PCBs.

Component Placement Is Essential for Thermal Management of PCBs

Effective thermal management of PCBs does not begin with selecting a heatsink. Component placement itself can have a significant impact on the resulting temperature.

High-power components should be positioned so that sufficient space is available for heat dissipation and so that heat from several sources does not unnecessarily accumulate in one area.

As Vaclav Ambroz, Head of the Technical Department, explains: “During the design process, it is important to consider the distance between heat sources, the placement of thermal vias, airflow direction, heatsink location and the overall dimensions of the device, as well as the temperature sensitivity of surrounding components.
It is also important to consider the entire device. A PCB is usually not an isolated system – its thermal properties are affected by the enclosure, heatsink, ventilation and surrounding components. There are quite a lot of possibilities for heat to accumulate on a small PCB.”

Passive and Active PCB Cooling

Heat dissipation methods can generally be divided into passive and active cooling.

Passive Cooling

Passive cooling uses the PCB construction and additional components without powered cooling mechanisms. Examples include:

• copper areas,
• thermal vias,
• heatsinks,
• heat spreaders,
• thermally conductive materials,
• metal-core PCBs,
• optimized component placement.

The main advantages of passive solutions are simplicity and high reliability.

Active Cooling

Active cooling uses additional mechanisms to remove heat, including:

• fans,
• forced-air cooling,
• heat pipes,
• liquid cooling,
• thermoelectric cooling.

For devices with a very high power density, a combination of several cooling methods may be necessary.

Thermal Management in HDI PCBs

Increasing electronic miniaturization creates another challenge, as Radim Vitek, Head of Production, explains:
“The more functions have to be placed in a smaller area, the less space remains for conventional thermal structures. HDI boards make it possible to achieve a high interconnect density using microvias, fine traces and sequential lamination. At the same time, the board construction must provide sufficient electrical and thermal performance. Thermal design therefore has to be part of the HDI design from the very beginning.”

This is particularly important for modern BGA packages and high-performance processors, where a large number of electrical connections and a high thermal load are concentrated in a relatively small area.
Thermal design must therefore be considered as an integral part of HDI construction from the early design stages.

Thermal Cycling and PCB Reliability

Thermal management of PCBs is not only important to prevent electronic devices from overheating. Long-term reliability is equally important.
Repeated heating and cooling causes thermal expansion of individual materials. When different materials have different coefficients of thermal expansion, mechanical stress can occur.
This can affect, for example:

• vias,
• solder joints,
• PCB layers,
• connections between the PCB and components.

For demanding applications, it is therefore not sufficient to verify only the maximum operating temperature. The behaviour of the board during long-term operation and repeated thermal cycles must also be considered.

How Can Thermal Management of PCBs Be Verified?

“The thermal management design should subsequently be verified through both simulation and practical measurement. Thermal imaging cameras are one useful tool, as they allow the temperature distribution across the entire PCB to be visualized during operation and local hotspots to be identified. This is why prototype manufacturing is important: testing can reveal weaknesses in the design,” says Radim Vitek.

Vaclav Ambroz adds:“It is important to test printed circuit boards under conditions that correspond to their actual use. A board may operate without problems at laboratory temperature or during our tests, but at a higher ambient temperature or maximum load, critical areas may appear that cannot be identified from the design alone and may not be detected by functional testing.”

Thermal Management Starts with PCB Design

With modern electronic devices, heat dissipation can no longer be addressed only at the end of the development process. Thermal management of PCBs must be integrated with the electrical, mechanical and manufacturing design.
The following factors should therefore be considered together during PCB design:

1. power dissipation of individual components,
2. component placement,
3. current load,
4. copper thickness,
5. multilayer PCB construction,
6. PCB material,
7. thermal vias,
8. cooling method,
9. operating temperature,
10. expected thermal cycles.

IPC lists IPC 2152 among the standards related to PCB design and also addresses other areas of PCB design, including HDI structures.

The Future of Thermal Management of PCBs

The development of electronics is moving towards higher performance, greater miniaturization and higher component density. This is particularly evident in AI infrastructure, data centres, automotive electronics and telecommunications equipment.

As power density increases, the way thermal management of PCBs is designed will also evolve. Simply adding a larger heatsink is no longer enough. An effective solution increasingly depends on a combination of the right material, stackup construction, copper areas, thermal vias, component placement and the overall cooling system.
For PCB manufacturers, this means that thermal management of PCBs is becoming an integral part of the PCB design itself.

The earlier thermal requirements are considered, the better the PCB construction, manufacturing process and resulting reliability of the electronic device can be optimized.

Radim Vitek, Head of Production, and Vaclav Ambroz, Head of Technical Production Preparation, both at Gatema PCB, shared their expert insights into the thermal management of PCBs.

[6] Thermal Management in a 3D-PCB-Package with Water Cooling – Scientific Figure on ResearchGate.
Available from: (PDF) Thermal Management in a 3D-PCB-Package with Water Cooling a https://www.researchgate.net/figure/R-measurements-and-FEM-results-of-the-3D-packages_fig3_224758911 [accessed 20 Aug 2026]