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Heat Sink In Your Electronics

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In today’s modern electronics, electronic devices are becoming more powerful and require high processing power. Thus, designers and engineers are making the components smaller, which is raising the miniaturization world. 

The greater performance power means higher thermal energy from the devices and components. Overheating the electronic components can lead to system performance degradation or system failure.  Thus, to tackle this, you need a heatsink. If your room has things like AC, these devices can be strategically attached to the circuit board. 

They help keep things running smoothly by absorbing the excess heat from your devices. But to get the most out of them, strategically place the heat sink. So, in this article, we will check everything about heat sink on PCB. 

What is a Heat Sink on PCB?

A heat sink on a PCB is a component that helps increase the heat flow away, as illustrated by electronic components like ICs, transistors, and power devices. 

The primary function of a heat sink on a PCB is to maintain the temperature of these components by absorbing and dissipating heat. It works on the principle of conduction. The heat naturally flows from the high-temperature area to that of the low-temperature area. 

Heat sinks are made of copper and aluminum, which are excellent thermal conductors. Thus, when a component on a circuit board generates heat, the heat is conducted through the PCB substrate to the heat sink.

Best Type of HeatSink

You can find the heatsink of the below types:

Active Heat Sink

By adding components, active heatsinks dissipate heat more efficiently than passive ones. These heatsinks have fans or blowers that actively move air across the fins, increasing heat exchange. 

In densely packed components or situations with limited ventilation, they are invaluable. Fans or blowers provide cooler air over the heatsink’s fins to improve heat transfer. In applications that demand large heat dissipation in tight places, active heatsinks are appropriate for microprocessors and regulators.

Passive Heat Sink

Electronic equipment, particularly PCB boards, uses passive heatsinks to cool small components. Instead of active heatsinks, they use airflow to transfer heat. Passive heatsinks use metal bases with expanded fins to assist heat dissipation. 

These heatsinks direct heat from microprocessors to fins. As heated air rises, colder air replaces it, adjusting component temperature. Their simple and effective cooling solution is ideal for situations with natural airflow.

Copper and Aluminium HeatSink

Copper and aluminum heat sinks have different benefits. Copper’s high thermal conductivity speeds up electrical gadget heat dissipation. Copper heat sinks are more expensive and heavier than aluminum ones. 

Aluminum heat sinks are lighter and cheaper than copper ones, but they transmit heat less well. When utilized in thin sheets with copper, they can provide structural stability. Many aluminum heat sinks have slender metal fins to increase convection heat dissipation. 

The base or contact plate and fins of some heat sinks are made of copper and aluminum. This combination balances cost and weight with effective heat transfer.

Factors While Selecting the Right Heat Sink for Your Design

Component Layout and Placement

You have to strategically place the heat-generating components so that they maximize the airflow and help dissipate the heat flow. Besides, grouping and combining the high-power components can help concentrate the heat in a specific area to make it easier to manage. Ensure sufficient clearance for the heat sink to avoid interference with other components. 

Placement of Thermal Via

PCB design relies on Thermal Via Placement for heat dissipation and thermal management. Strategically placing thermal vias in the PCB architecture creates heat transfer routes between layers. Designers install direct heat dissipation channels near heat-generating components like processors and power modules to avoid thermal stress and damage. 

Designers improve PCB heat transmission via improved distribution, density, arrays, and stitching. Importantly, PCB stack up—the order and composition of PCB layers—determines thermal via placement to optimize heat transport throughout the board. Strategic thermal via placement is critical to managing heat dissipation and maintaining electronic device performance and reliability.

Material Selection

The selection of material impacts the system’s thermal performance and cost. Thus, when selecting the right PCB materials for the heat sink design, ensure you go for high heat conductivity. 

For example, copper is widely accepted due to its highly conductive nature, while aluminum is the second most popular choice as it balances both thermal performance and production costs. Some designs also use composite materials to balance weight, cost, and performance. 

Thermal Interface Materials (TIM)

Thermal Interface Materials (TIMs) optimize heat transfer between heat sinks and heat-generating components in heat sink design. Designers consider thermal conductivity, thickness, and compliance when evaluating thermal pads, pastes, and phase change materials. These qualities are crucial for choosing the best TIM for heat transfer in the application. 

Precise TIM application ensures uniform coverage and minimal air gaps between the heat sink and components. By establishing maximum thermal contact, TIMs reduce thermal resistance and improve electronic device thermal management.

Choosing the Right Heat Sink

Heat Generation: Determine the amount of heat generated by the PCB component. This kind of information is essential for the selection of a heat sink with the proper thermal capacity.

Size and Shape: You need to consider the size and shape of the heat sink. Ensure it fits within the available space on a PCB without obstructing the airflow. The shape of your heat sink should efficiently dissipate the heat.

Selection of Material: If you check the available heat sinks on various PCBs, they are mainly made of copper and aluminum. Aluminum offers a cost-effective solution, while copper offers better thermal conductivity but is more expensive than aluminum. Thus, before selecting the materials for your heat sink, consider your budget and the thermal conductivity performance required by your project.

Design of Fin: If you check the fin design for your heat sink, you will find various options like straight, pin, and folding fins. Fin design impacts heat diffusing surface area and airflow resistance. Choose a cooling design that fits your demands.

Thermal Interface Material (TIM): The space between the heatsink and components requires the best thermal interface. It ensures better heat transfer through the heat sink. High-quality thermal materials help reduce thermal resistance, boosting conductivity. So, consider this thermal interface material before selecting the right heat sink.

Heat Sink Fin Design

The primary thing in a heat sink is the fin design. It plays a crucial role in the efficiency of heat dissipation from electronic components. Let’s check out some of the final design considerations: 

Geometry – The shape and geometry of the heat sink impact its performance. Some of the typical fin shapes include straight, wavy, and pin. Various shapes and geometry give the different surface areas, which provide various geat transfer efficiency and airflow resistance. 

Density – The number of fins per unit area affects the heat transfer surface area. Greater fin density improves surface area and airflow resistance. Designers must balance fin density to maximize heat dissipation and heat sink airflow.

Thickness – The thickness of the heat sink affects the thermal conductivity and structural integrity. Thicker fins increase wind resistance and weight but boost structural stability. Thinner fins improve heat transfer but are more fragile.

Spacing – Heat sink airflow channels depend on fin spacing. Narrow spacing improves heat transmission but reduces airflow. Increased spacing reduces airflow resistance but may lower heat dissipation. Airflow velocity and heat load determine fin spacing.

Fin Profile – The heat sink’s design affects airflow and heat distribution. Your application requirements determine the system’s airflow profile, including turbulent and laminar. Shaped fins promote airflow around the heat sink, increasing heat dissipation.

Installation Procedure for Heat Sink in your PCB

  • Choose the right heat sink, considering the dimensions and requirements of your PCB. Ensure that it’s compatible with the components generating heat.
  • Then, you must prepare the PCB, which involves cleaning the surface while mounting the heat sink.
  • Then, the next step will be to apply the thermal interface material. Cover heat sink-contact components with a thin layer of thermal paste or pad. This improves component-heat sink transfer.
  • Place the heat sink carefully on the component, trying to align it properly with the adhesive pads or mounting holes. 

Apply pressure to ensure good contact between the heat sink and the components. 

  • Use mounting clips or screws to secure the heat sink. Check for looseness or wobbling.
  • Check that the heat sink is cooling and makes excellent contact with all components. Insufficient contact can reduce thermal performance.
  • Power on the device and check the heat sink temperature to ensure heat dissipation. Make any necessary changes. 

Conclusion

Heat sink integration with PCB design is crucial for efficient heat dissipation. It helps to prevent overheating and ensures the device’s reliability.

The choice between the various types of heat sinks depends on the application requirements. Besides,  the selection of a heat sink involves heat generation, size, shape, fin design, and material selection. Thus, balancing thermal performance, space constraints, and cost is crucial when selecting the most suitable heat sink for a particular application.

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About the Author
Rashila
I am an Electrical and Electronics Engineer, and I have 5 years of work experience with electronics and communication jobs. I'm the full time content creator of ELE company.
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