Table of Contents
How to Manage Heat in PCBs: Techniques, Materials & Best Practices
This article was originally published in Feb 2024 and last updated on June 29, 2026.
The constant rise in component power density in contemporary electronics makes PCB thermal management a crucial reliability issue. Overheating at the junction may lead to various failure mechanisms, causing circuit failure and decreasing the operating time of the system.
This paper deals with heat sources, heat dissipation within PCB assembly, thermal properties of several substrates (FR-4, MCPCB, ceramics), and three ways of heat dissipation—conduction, convection, and radiation.
Some of the widely used techniques such as thermal vias, heat sinks, thermal interfaces, cooling systems, proper PCB design, thermal analysis software, and mechanical tools are discussed. The relevant standards should be reviewed (IPC, JEDEC, etc.). The objective is to provide brief but practical information to help the design engineer choose appropriate material, component placement, and cooling technology for his application.
Heat Generation in PCBs
Heat generation in PCBs comes from the conversion of electrical energy to heat energy. The identification of these heat sources is important for successful thermal management.
Active Components:
- Microprocessors and Central Processing Units (CPUs): Highly consuming electrical power and performing intensive processing operations lead to production of high amounts of heat.
- Power Transistors: Used for amplification and power control purposes, producing large amounts of heat.
- Light-Emitting Diodes (LEDs): Produce high-intensity lights for illumination purposes; produce large amounts of heat.
- Memory Modules: Produce heat due to their high-speed operation during read and write processes.
Passive Components:
- Resistors: Conversion of electrical energy to heat energy, particularly in high-power resistors.
- Inductors/Transformers: Core and winding losses resulting in heat dissipation.
- Capacitors: Dielectric losses in high-frequency capacitors result in heat dissipation.
Connectors and Interconnects:
- High Current Paths: Traces and connectors carrying large currents generate resistive heat.
- Thermal Vias: Although the original intention of via design is heat dissipation, if designed improperly, the vias themselves can also generate heat.
Key Factors Influencing Heat Generation
Some factors determine the amount of heat generated in a PCB:
| Factor | Impact on Heat Production |
| Power Consumption | Higher power levels directly increase heat production |
| Operational Frequency | Higher frequencies increase switching losses |
| Component Density | Dense placement causes local hot spots |
| Trace Width/Thickness | Narrow or thin traces have higher resistance |
| Duty Cycle | Continuous operation causes more heat buildup than intermittent use |
| Ambient Conditions | Temperature, humidity, and airflow affect heat dissipation |
| Voltage/Current Levels | Higher levels increase power dissipation |
| Signal Integrity | Poor signal integrity causes additional power loss |
Consequences of Poor Thermal Management
Ineffective cooling of components may result in several problems:
- Thermal Runaway: As the temperature of the component increases, its power consumption rises, thus causing an uncontrollable destruction of the component. The self-propelled process may destroy the component within only a few seconds.
- Signal Distortion: High temperatures may change the electrical properties of the materials of the printed circuit board and may cause changes in the impedance.
- Shortened Lifespan of Components: According to the Arrhenius equation, each increase in the operational temperature by 10 degrees will shorten the lifetime of the semiconductor component twice.
- Mechanical Stress and Warping: Different thermal expansion coefficients of the materials (copper, FR-4, etc.) cause mechanical stress that, in its turn, causes solder joint failure, delamination, and warping.
- Product Recall and Brand Deterioration: In the most severe case, thermal failures at the site may result in product recalls and brand deterioration that is important for any electronics producer.
Thermal Management Principles: Heat Transfer in PCBs
The thermal management of the printed circuit boards (PCBs) involves the use of three major modes of heat transfer:
Conduction
Conduction is the mode of heat transfer via a solid material. Conduction transfers heat in the solid material from those parts that have generated heat to other cooler portions of the circuit board. Copper has very high thermal conductivity with a value of 385 W/m·K and thus makes a good conductor of heat. The major way of transferring the device junction-to-ambient thermal resistance (θ JA) in the circuit board is by conduction.
Convection
Convection is the heat transfer through the fluid (either air or liquid). In convection, either fans or liquid are used to dissipate heat from the PCB in the form of forced air or natural convection, respectively.
Radiation
Radiation is heat transfer via electromagnetic waves. Though in the case of PCB applications, radiation effect is minor compared to that of conduction and convection.
PCB Material Selection for Thermal Performance
Thermal performance is affected by the choice of substrate material. The higher the thermal conductivity of the material, the better its heat dissipation performance.
Thermal Conductivity Comparison
| Material | Thermal Conductivity (W/m·K) | Typical Applications |
| FR-4 (Standard) | 0.3-0.4 | General consumer electronics |
| FR-4 (High-Tg) | 0.3-0.4 | Industrial, automotive (up to 170°C Tg) |
| Polyimide | 0.1-0.4 | Flexible PCBs, high-temperature environments |
| Rogers Materials | 0.5-1.0 | RF and microwave applications |
| Aluminum MCPCB | 1-5 | LED lighting, power electronics |
| Alumina (Al₂O₃) Ceramic | 24-30 | High-power RF, thick-film circuits |
| Aluminum Nitride (AlN) Ceramic | 170-230 | High-performance power modules, extreme power density |
| Copper (Reference) | ~385 | Thermal planes, heat spreaders |
How to Choose the Right Substrate Material
When selecting the correct base material, there are many factors to consider. These include:
- Power Levels: Circuits with power levels less than 5W need FR-4. If the circuit has medium power levels (5-50W), then it requires MCPCB or high-Tg FR-4. If the power level is more than 50W, then aluminum nitride or ceramic substrate is recommended.
- Temperature of Operation: Glass transition temperature of standard FR-4 is 130-140°C. If the operating temperature is higher than 90-110°C, then high-Tg FR-4 or polyimide material is recommended.
- Frequencies Needed: In case of RF and microwave frequencies, you will have to choose Rogers material.
- Mechanical Requirements: Polyimide is needed for flexible designs while metal core or ceramic substrates can be helpful for rigid designs.
5 PCB Thermal Management Techniques
Effective thermal management during the design of a PCB involves heat spreading, heat sinking, and active cooling. It is dependent on a number of factors such as power density, available space, cost objectives, and environmental factors. The following section provides an overview of the various methods utilized in today’s PCBA industry. The thermal management techniques are:
- Thermal Vias: Small holes within a PCB that enable heat distribution.
- Heat Sink: Heat sink is a device with fins for increasing surface area to dissipate heat.
- Cooling Systems: These involve air or liquid cooling.
- Thermal Interface Material (TIM): This is any material that enhances heat dissipation from component to heat sink.
- Thermoelectric Cooler (TEC): This is any device providing cooling for a particular component.
The following provides more detail regarding each thermal management technique:
Thermal Vias: Design and Implementation
Thermal vias are vertical interconnections that enable heat transfer from one PCB layer to another. They are crucial thermal enhancers, In particular within multilayer PCBs.
Thermal vias work by allowing heat to move away from hot parts and so preventing overheating of a specific spot while increasing the total thermal performance.
Best Practices for Thermal Via Design
- Diameter: Drill size should normally be no larger than 8 mils (0. 2 mm) to avoid solder wicking. Usually, a 0. 5 mm drill diameter and a roughly 0. 4 mm finished hole size are used.
- Spacing: Position the vias such that the distance between them is around 1. 2 to 1. 5 of their diameter. If the placement is very close, then you may be in danger of damaging the board physically, and if too far apart, then heat dissipation may not be efficient.
- Via Filling: For heat dissipation purposes, copper-filled vias are ideal. Normally, simple plated vias are fine though not as good. A solder fill may be helpful but definitely inferior to copper.
- Number of Vias: Place a sufficient number of thermal vias under heat-generating parts to equally spread out the heat. Thermal resistance is inversely proportional to the number of vias.
- Proximity to Planes: Make the via barrel as close as possible to the copper planes to help heat conduction.
Heat Sinks: Passive vs. Active
Heat sinks are equipment attached to heating parts to enlarge the heat dissipation area.
- Passive Heat Sinks: Dissipate heat only through natural convection and radiation. Typically made from metals with very good thermal conductivity like aluminum, or copper, they often feature multiple fins to provide a heat transferring surface area that is greater than the one of a larger block of the cooling material. Besides being more straightforward and reliable (because it has no moving parts), passive heat sinks are also less expensive to manufacture and maintain.
- Active Heat Sinks: Besides the heat sink itself, they incorporate parts like fans or blowers that help throw heat away from the sink by forced air, that is, forced convection. Many good things come with active heat sinks like being highly efficient, but at the same time, they are more complicated, more expensive and even can fail at the level of their moving parts (fans).
How to Include Heat Sinks in Your PCB Design
- Method of attachment: For through-hole components, you can use spring clips; for surface-mount devices, adhesives or thermal tape can come in handy; and for the larger components, screw-mounted brackets. Make sure that the clamping pressure is sufficient for intimate thermal contact.
- Mechanical clearance: Make sure the fin height and airflow paths have enough room. Also, the components upstream should never block the airflow.
- The right position: Passive heat sinks will perform best if the fins are vertical, since this allows the air to flow freely. A horizontal arrangement of fins will cause a loss of efficiency in the natural convection process.
- Provide mechanical support to PCB: A heavy heat sink gets supported very well if the weight is directly transferred to the chassis through mounting holes with standoffs. Without this, strain on solder joints is inevitable.
- Electrical clearance: Ensure that creepage and clearance distances meet IPC standards. Where electrical isolation is needed, insulating pads are necessary.
Cooling Systems for PCB: Air Cooling vs. Liquid Cooling
If the heat generated by a component is too much for the local heat sinks to handle, system-level cooling becomes necessary:
- Air Cooling: Involves moving fans or blowers to change the air over the PCB in expectation to heat dissipation. It is a straightforward, cost-effective, and highly used method. Even so, air cooling might not be effective enough for applications with very high power or very densely packed assemblies.
- Liquid Cooling: It is the practice of transporting a liquid coolant through pipes or channels for heat removal. In that case, liquid cooling is more effective and is the right choice for high-power or high-density PCBs; Still, liquid cooling is more complicated, costly, and needs careful leak prevention.
Designing Efficient Cooling Systems for PCBs
- Airflow management: Keep vents for intake and exhaust open. Try to avoid recirculation. If necessary, use ducting to direct airflow across critical components.
- Coolant selection: Water-glycol mixtures have very good heat capacity but need corrosion inhibitors. Dielectric coolants are the best choice when the short-circuit risk is to be eliminated.
- Component placement: In case of air-cooled boards, locate the highest-power components closest to the air intake. When it comes to liquid-cooled boards, reserve cold plates for just the highest-dissipating components; the rest of the devices (of lower power) remain air-cooled.
- Redundancy and safety: To make sure that, in case of a failure of one cooling unit, the system will still be operational, consider redundant fans or pumps for high-availability systems. Don’t forget to add temperature sensors and thermal shutdown circuitry.
Thermal Interface Materials (TIMs)
Thermal Interface Materials (TIMs) are the solutions to improve heat transfer between components and heat sinks. Below are some common ones:
- Thermal Grease: This kind of material has superb thermal conductivity capabilities but it can be a bit untidy and tricky to work with.
- Thermal Pads: Besides being simpler to use compared to grease, the thermal conductivity of these is also pretty good.
- Phase Change Materials (PCM): These are initially in the solid state and at room temperature. Once heated, they liquefy and fill the hollows, thereby providing a high level of thermal conductivity.
- Thermal Adhesives: Apart from thermal conductivity, these also provide a form of mechanical attachment.
Applications and Selection Criteria in PCB Design
- Thermal capability: For components with low power output (< 2 W), thermal pads will suffice. But, for high-power components (> 10 W), thermal grease or PCMs will be the best choice as they offer the lowest thermal resistance.
- Mechanical aspects: If the surfaces are very uneven, one should use grease or PCMs, which can flow into the gaps. For flat surfaces with well-controlled clamping, pads are enough.
- Assembly & production: Pads are quicker and more amenable to mass production. Occasionally, the use of grease may require a dispensing step that needs to be controlled and will add to the process time.
- Thermal cycling stability: Usually the pads and PCMs perform better for stability when exposed to repeated temperature changes against silicone greases.
- Electrical insulation: When the components have exposed electrical pads, non-conductive TIMs should be the choice.
Thermoelectric Coolers (TECs)
Thermoelectric coolers (TEC), alternatively called Peltier coolers, take advantage of the Peltier effect to establish a temperature difference between two materials at a junction. These are capable of transferring heat from one side to another upon the application of an electric current, because of this accommodating cooling on one side and heating on the other.
TECs Applications in PCB Design
TECs find their way into PCB assemblies, mostly where cooling below ambient locally is mandatory or temperature stabilisation with a high degree of accuracy is a must, for example, laser diodes, infrared sensors, fibre-optic transceivers, and medical diagnostic equipment.
On top of that, to most efficiently use a TEC in a PCB, the main points to think about are:
- Hot-side cooling: Equip the hot-side with a heatsink, and often also a fan, to be able to dissipate not only the pumped heat but also the electrical power consumed by the TEC. The heatsink has to be sized based on the total thermal load which will be bigger than the component’s own dissipation.
- Mounting: The TEC has to be sandwiched between the component and the heatsink, with the clamping pressure being just right; too little will raise the thermal resistance and too much can cause the ceramic plates to crack.
- Power supply: A constant DC current source should be provided; current ripple is an efficiency killer.
- Condensation risk: When the cold side is below the dew point, water droplets may form. In case the environment is humid, conformal coating or a sealed enclosure might be considered.
How to Choose the Right Thermal Management Strategy
Selecting the appropriate thermal management strategy requires a systematic evaluation of several factors. The following decision matrix provides a starting point:
| Power Level | Space Constraints | Recommended Strategy |
| < 5W | Ample | Natural convection + passive heat sink + standard FR-4 |
| 5-50W | Moderate | Forced air cooling + thermal vias + MCPCB or high-Tg FR-4 |
| > 50W | Tight | Liquid cooling / heat pipes / vapor chamber + ceramic substrate |
| Localized Hot Spots | Any | TEC for precision cooling + thermal via arrays |
| Cost-Sensitive | Any | FR-4 + optimized layout + adequate copper weight (≥2 oz for high-current paths) |
Decision Flow
- Calculate Total Power Dissipation: Estimate the overall power dissipated by all the components on the PCB.
- Find Heat Flux Density: Divide the total power by the area of the board to get W/cm²
- Consider Space Constraints: Find out how much space there is for placing heatsinks, fans, or other cooling equipment.
- Decide on the Substrate Material: FR-4 for low power, MCPCB for medium power, ceramic/AlN for high power.
- Identify the Corresponding Cooling Method: Passive, active air, or liquid cooling given power density.
- Simulate and Confirm: Employ thermal simulation to check the design before making a prototype.
- Create a Prototype and Conduct Tests: Confirm with real thermal measurements (thermocouples, thermal imaging).
PCB Layout Strategies for Optimal Heat Dissipation
Component Placement and Spacing
There are numerous ways through which the heat can be managed within the components, but one of the most effective and efficient ways is the placement of components:
- Separate the Heat Generating and Heat Sensitive Components: For example, make sure that the crystal oscillator, analog front-end, and accurate voltage reference should be placed far away from the high-power components that generate heat.
- Locate the High Power Components at the Edge of the Circuit Board: Not only does it make the process of transferring the heat to the surrounding environment easier, but it also facilitates the air flow.
- Proper Component Spacing: As heat is generated where there are dense components, it makes sure that the heat is dissipated properly. That is why it is necessary to maintain proper spacing between the components.
- Air Flow Direction: In case when the cooling is done by forced air, then it is essential that the high-power components should be placed in the area from where the air is flowing, while heat-sensitive components should be located where the air flows towards.
Thermal Zones and Isolation
- Thermal Zone Development: Division of the PCB into thermal zones based on the quantity of heat generated by each part is an excellent method for carrying out the cooling process. Each thermal zone can be cooled using a unique cooling process.
- Thermal Barriers: Application of thermal barriers is an excellent way of segregating regions which have varied thermal characteristics. This ensures that heat generated in one thermal zone does not reach other thermal zones.
- Thermal Isolation: In case there is heating and cooling regions in adjacency, you can install thermal isolation slots between them.
Copper Pour and Heavy Copper Design
- Use Copper Planes for Heat Dissipation: large copper surfaces (power and ground planes) should be regarded as heat dissipation devices – they help dissipate heat from hot components to other board areas.
- Think About Heavy Copper: PCBs having copper layers of 2 oz and higher (these are heavy copper PCBs) are great for both thermal management and current handling capabilities. Heavy copper PCBs (3-4 oz and above) can handle high current levels and are good for heat dissipation.
- Thermal relief pads: In order to ensure that the heat generated by the components does not travel through the copper planes and result in high thermal resistance, thermal relief pads should be used. The solder joint may be one of the potential points of failure when assembling PCB. Thermal relief pads help avoid cracks.
Common PCB Thermal Management Mistakes to Avoid
According to our engineering experience, this is the list of top mistakes made in thermal management along with the solutions:
- Insufficient or Absent Thermal Interface Material
- Problem: Small pockets of air between component and heatsink cause high thermal resistances.
- Solution: The right type of TIM should always be used between overheating components and heatsinks. The proper design of TIM could decrease thermal resistance to 5-6° C.
- Failure to Consider Thermal Via Filling
- Problem: Thermal vias filled with air have very high thermal resistance since there is air in them.
- Solution: Use copper filled or plated vias for maximum thermal conductivity.
- Ignoring Ambient Operating Conditions
- Problem: Designs that are tested at room temperature fail when ambient temperature is higher.
- Solution: The thermal analysis should consider the limits in temperature, humidity and air speed.
- Arrangement of Several Power Units
- Problem: Positioning of several high-power components causes overheating in certain areas.
- Solution: Distribute high-power components across the board and take into account ventilation.
- Dependency Only on Simulation, No Physical Validation
- Problem: Condition for boundaries in simulation can differ from those in reality.
- Solution: Thermal simulation has to be followed by practical testing of the prototype using thermocouples or thermal cameras.
- Inhomogeneous Copper Distribution in Interior Layers
- Problem: Non-homogenous distribution of copper results in thermal stresses and distortion of PCB.
- Solution: Homogenous copper distribution has to be achieved using copper balancing.
- Ignoring Thermal Properties of Solder Joints
- Problem: High concentration of voids in solder joints under thermal pads reduces thermal conductivity.
- Solution: Volume and process of reflow of solder paste has to be optimized to minimize voids.
- Overengineering without cost-benefit analysis
- Problem: Using sophisticated cooling methods for low-power components means wasting money.
- Solution: Thermal solution should match thermal demands.
Thermal Simulation Tools for PCB Design
Thermal simulation proves to be an extremely helpful way to get to know the thermal profile and see whether the thermal management technologies are effective enough even without developing the first prototype.
ANSYS Icepak:
- Advanced software product for thermal simulation of electronic products based on CFD.
- Enables one to perform various simulations of heat transfer methods, including conduction, convection, and radiation.
- May be integrated with other products from ANSYS to conduct multiphysics analysis (thermal-stress coupling).
- Allows representing quite complicated configurations and detailed models of single components.
- Primarily designed for electronics with high power level, automotive and consumer electronics.
Mentor Graphics FloTHERM:
- Specialized thermal simulation software for electronic products.
- Extensive databases of components with numerous thermal parameters of components.
- Easy-to-use graphical user interface and all operations are made using drag-and-drop mechanism.
- Provides air flow, temperature and heat dissipation of components, boards and whole systems.
- Ideal solution for working on design and optimization of PCB, server and data center cooling systems.
SolidWorks Thermal Simulation:
- The Thermal Analysis comes naturally integrated into the SolidWorks CAD software.
- It helps in carrying out thermal, structural and fluid flow analyses.
- Design Optimization using Parametric studies.
- Perfect choice for thermal analysis of mechanical assemblies, electronic assemblies, and printed circuit boards.
When to Simulate vs. When to Prototype
- With simulation, you gain an important advantage in the initial stages of design as it allows to compare different alternatives and optimize your layout. Moreover, it simulates different scenarios on time and on budget.
- Prototype nowadays becomes a necessary step for final verification. Accuracy of simulation depends upon accuracy of the input data-material properties, boundary conditions and component models.
- Most Likely Scenario: Simulation would become a basis for making design choices and eliminating less effective solutions, but eventually you would have to prototype the real product to get the minimum cost and maximum confidence.
Thermal Management Standards and Regulations
Thermal Management Industry Standards
There are numerous thermal management industry standards, such as IPC-2221, IPC-2152, and JEDEC standards that cover thermal management of PCBs. These standards provide a roadmap for the thermal design, testing, and compliance.
Compliance and Testing Procedures
To ensure that thermal management standards have been met requires significant testing and validation. Apart from the thermal simulation and prototype testing, industry guidelines must also be followed.
Conclusion
Effective thermal management of the PCBs is crucial when we desire to increase the reliability and improve the performance of electronic equipment. Knowing the heat sources, understanding the heat transfer concepts, and investigating various thermal management techniques is required in order to create an efficient and reliable PCB.
Implementing effective thermal management techniques in the design process of the PCB ensures the highest efficiency and longer life of the electronic device. In addition, by employing latest technologies and industry standards, the designers may develop new solutions to the thermal problems of electronics.
Our engineering team provides a total PCBA thermal management solution to our customers ranging from material selection and thermal simulation to prototype development and high-volume manufacturing. We help our clients in the automotive, medical, industrial, and consumer electronics industries to tackle their challenging thermal issues.
Need Expert Assistance with Your PCB Thermal Management Challenges?
Our engineering team provides complete PCBA thermal management solutions, covering material selection, thermal simulation, prototype development, and high-volume manufacturing. Whether you're developing products for automotive, medical, industrial automation, or consumer electronics, we help solve complex thermal challenges and improve long-term product reliability.
FAQs about PCB Thermal Management
Thermal vias are interconnections made vertically to move the heat from the surface of a printed circuit board to its inner layers or the opposite side. These are usually filled or covered with conductive materials such as copper to increase the efficiency of heat transmission. The role of thermal vias is to provide a means for the dissipation of heat.
Thermal relief pads are employed to ensure that there is a connection between heat generating parts and the copper plane without creating any thermal resistance. The use of such pads ensures that the heat generated can be managed in order to avoid warping or any other damage to the PCB. They increase thermal performance by regulating heat transfer from the components.
The thermal zones separate the PCB into regions depending on the amount of heat produced by various devices mounted on the board. Thermal management of such regions in isolation prevents interference of the heat produced in hot regions with that in sensitive regions.
Layers and their stacking play an important role in determining the thermal behavior of the multi-layered PCBs. The inclusion of dedicated thermal layers or thermal spreaders in the stack up of the PCBs can aid in heat dissipation. The stack up design of the layers is important for efficient heat management.
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