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What Are Three Factors You Should Consider When Choosing a Heat Sink?

The increasing size of modern electronic devices has led to an increase in heat dissipation density. The heat generated at this point affects the performance of electronic devices. To maintain efficiency and longevity, an effective means of dissipating heat from electronic devices is required.

At this point, a thoughtfully chosen heat sink can be a good solution to the problem of heat dissipation from electronic components. While electronic components have some of their own cooling properties, with a heat sink is also a good choice.

When choosing the right heat sink, you need to carefully consider three factors. These include careful evaluation of design requirements, material properties, and thermal resistance management. By choosing the right heat sink, you can effectively improve thermal performance, optimise energy efficiency, and prevent overheating.

At Trumonytechs, we can provide you with specialized thermal solutions. If you simply need thermal materials, then our interface materials are also an ideal option.

Table of Contents

What are radiators used for?

The heat sink is usually made from a thermally conductive material (copper/aluminum) designed to dissipate heat by liquid cooling, natural convection, forced convection or radiation. Its main purpose is to conduct heat from the heating element to a cooler environment. As an example, the conventional way of heat dissipation is that a solid emits its temperature directly into the air, thus cooling it. The advent of heat sinks, on the other hand, provides a thermal conductive medium directly between the solid and the air. It achieves good thermal conductivity by increasing the surface area of contact between the component and the coolant, combined with the thermal conductivity properties of the material itself, thus keeping the temperature below the maximum temperature specified by the equipment manufacturer.

However, different applications have different heat dissipation requirements. Therefore, you need to choose the right heat sink according to your current cooling needs. But don’t worry, Trumonytechs, as thermal management experts, we have the experience to take you through this step by step.

Thermal Resistance Management

Understanding Thermal Resistance and Its Importance in Heat Management

Thermal resistance is a key parameter used to evaluate the efficiency of heat transfer from a heat source to the surrounding environment. Measured in °C/W, it quantifies the temperature rise generated per watt of power consumption. The lower the thermal resistance, the better the system dissipates heat, thus ensuring that components remain within a safe operating temperature range.

Thermal resistance can be understood as the sum of several critical paths: the chip to the module enclosure, the enclosure and heat sink (thermal interface resistance), and the resistance between the heat sink and the flowing fluid. Each path affects the overall thermal resistance. And understanding how each part affects thermal resistance is critical to choosing the right heat sink. So how should you calculate thermal resistance? We’ll explain below.

Thermal Resistance Management

Calculating Thermal Resistance

In order to calculate thermal resistance effectively, it is important to know the maximum temperature rise allowed within the system in order to select the most appropriate heat sink. For example, from the ambient temperature to the maximum operating temperature of the equipment. This helps to determine the maximum allowable thermal resistance of the heat sink.

Similar to the TO-220 package, which is a semiconductor package commonly used in power electronics. In this case, the power consumption of the device will result in generated heat. The thermal resistance from the chip to the component case, between the case and the heat sink, and between the heat sink and the coolant must be considered. By calculating the power consumption and combining the individual resistances, the required thermal resistance of the heat sink can be determined.

The lower the thermal resistance of each path, the more efficient the heat transfer will be. This prevents overheating and ensures component life and reliability. Too much thermal resistance in any one path can lead to inadequate cooling, reducing performance or even causing equipment failure.

This can be a little tricky and requires specialised equipment to measure. Thankfully, Trumonytechs can provide specialist modelling analysis. We can go through the geometry and parameters of the heat sink to identify the heat sink that meets the highest requirements.

Methods for reducing thermal resistance

In order to reduce thermal resistance, it is important to use efficient Thermal Interface Materials (TIM) such as thermal grease or thermal pads, which bridge the small air gaps between the heating element and the heat sink, and can be used to fill these spaces with their high thermal conductivity to enhance heat transfer. Heat sinks, on the other hand, are another effective heat dissipation strategy, as they can be shaped to maximise the surface area of the heat sink by increasing the number of fins or adjusting the shape to achieve effective heat transfer. The two can work in tandem to effectively absorb and dissipate heat from the component to achieve low thermal resistance.

efficient Thermal Interface Materials

Material Selection

When designing a heat sink, the choice of material is critical to optimize heat dissipation and ensure the efficiency and longevity of the components. The two most commonly used materials for heat sinks and cooling solutions are aluminum and copper. Each material has its advantages and limitations, depending on the application.

Aluminum: Aluminium is widely used due to its cost-effectiveness and ability to be easily extruded into various shapes. It has good thermal conductivity and can be used in most conventional cooling applications. In addition, aluminum is lightweight, which is why it can be widely used in the electronics and automotive industries. However, aluminum’s thermal conductivity is only about half that of copper, which may not quite meet the needs of some high thermal conductivity applications.

Copper: Copper has excellent thermal conductivity – about twice that of aluminum. This is ideal for high thermal conductivity applications. Examples include power electronics, high-performance processors and LED cooling systems. Copper is also a material with excellent corrosion resistance compared to aluminum, making it ideal for corrosion-resistant applications. However, copper’s higher density corresponds to its heavier weight, which may make it less suitable for applications with high weight requirements. It is also more expensive than aluminum, making it less suitable for applications with limited budgets.

Other materials and composites: For extreme performance scenarios, composite solutions such as coated heat sinks and liquid cooled panels are ideal. These materials can provide enhanced performance such as improved heat transfer, corrosion resistance and weight reduction. By combining a metallic substrate with a thermally conductive coating, these materials increase heat transfer efficiency and reduce corrosion. Meanwhile, the use of liquid cooling technology in modern electric vehicles, such as Tesla’s battery cooling system, is a clear example.

Cooling Method & Design Type

Effective cooling is essential for maintaining the performance, reliability, and lifespan of electronic devices. There are two primary cooling methods: passive cooling and active cooling, each with specific applications depending on the system’s requirements. Additionally, design innovations in heat sink structures and thermal simulations are driving advancements in cooling technologies.

Passive Cooling vs. Active Cooling

Passive cooling relies on natural convection and radiation to dissipate heat. This approach involves no moving parts or additional power consumption, making it ideal for environments that require silent operation or systems without an external power source. Passive cooling solutions are commonly used in IoT devices, lighting systems such as LEDs, and low-power electronic devices. However, they have limited heat dissipation capabilities and are not suitable for high-performance or heat-intensive systems.

Active cooling, on the other hand, uses fans or pumps to increase the flow of air or liquid through a heat sink or cooling plate, thereby increasing the efficiency of heat dissipation. Active cooling is critical for applications such as high-performance computing, data centres and electric vehicles (EVs) that need to manage large heat loads. While active cooling systems are more complex and require electrical power, they provide a higher level of heat dissipation compared to passive solutions.

Heat Sink Shapes and Arrangements

The shape and arrangement of the radiator fins play a critical role in cooling efficiency. Common designs include straight fins, pin fins and curved fins, each of which is suitable for specific scenarios. For example, straight fins are easier to manufacture and are widely used in compact units. Needle fins, on the other hand, provide more surface area and are ideal for turbulent airflow conditions. Curved fins optimise airflow and improve heat dissipation in systems where space is limited.

Maximising surface area and optimising airflow patterns are key design principles. A larger surface area enhances heat exchange, while the airflow design prevents hot spots and ensures uniform cooling. These factors significantly affect the overall efficiency of the heat sink, so precise design choices are essential.

These can be evaluated using Trumonytechs modelling services to assess the thermal performance of different fin shapes and configurations.

Simulation and Optimization

Thermal simulation tools, such as SimScale and ANSYS, allow engineers to evaluate cooling designs before production. These tools predict heat flow pathways, identify thermal bottlenecks, and recommend the best material and structure combinations. Simulations reduce the need for costly prototypes and ensure that final designs meet performance requirements.

Making the Best Choice with Multiple Factors

Heat sinks serve as important thermal components in current electronic devices. Choosing the right heat sink assembly requires consideration of thermal resistance, material selection and design optimisation to ensure that electronic components operate within the manufacturer’s specified limits. By effectively dissipating heat from electronic components, we can ensure that electronic equipment operates at its optimum and prevent shortened lifespans due to overheating. If you have any questions, you can use our simulation solutions to determine the geometry and parameters of heat sink components for optimal heat dissipation.

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