The heat sink is an essential part of electronic devices. It removes the heat from electrical components by dissipating it into the surrounding air. Thus, heat sinks avoid overheating components that may cause failure or destruction.
Usually constructed from metals with high thermal dissipation coefficients, such as aluminum or copper, heat sinks improve the stability and durability of devices by regulating their working temperatures. They are used in CPUs, power transistors, and other high-power electronic systems where heat dissipation is critical.
What Is a Heat Sink?
A heat sink is a metallic object placed on top of a chip, such as a CPU, and its primary function is to handle heat. It works by taking heat from the component and cooling it through metal fins, which cool the chip. A heat sink is a passive device; it does not have any moving parts. However, it is often used with a fan that blows hot air in the opposite direction. Moreover, it can be incorporated into a liquid cooling system that carries the heat through pipes to another location.
Applications of Heat Sinks in Electronics
Some of the most frequent uses of heat sinks are as follows:
- Power Amplifiers: In power amplifiers, heat sinks are employed to reduce the temperature of the transistors. They help to remove the heat and prevent the transistors from being damaged or affected by heat, thus ensuring their stability.
- CPUs: In computers, heat sinks are used to cool down CPUs and graphic cards. These components produce quite a lot of heat when performing various processing tasks, and heat sinks are useful in dissipating this heat quickly to avoid the performance of the hardware or even damage it.
- Optoelectronics: Some devices, such as LEDs and lasers, need heat sinks to manage the excessive heat they generate. If not cooled adequately, these components may overheat, which will definitely lower their efficiency and effectiveness. Heatsinks allow temperature control and thus enable the devices to function as expected in the long run.
Heat Sink Tolerances:
| Factor | Typical Tolerance |
| Dimensional Tolerance | ±0.1 mm to ± 0.5 mm |
| Flatness | ± 0.05 mm to ± 0.1 mm over 100 mm |
| Perpendicularity | ± 0.1 mm per 100 mm |
| Parallelism | ± 0.1 mm per 100 mm |
| Surface Finish (Ra) | 1.6 µm to 3.2 µm |
| Hole Location | ± 0.1 mm |
| Fin Thickness | ± 0.1 mm |
| Fin Spacing | ± 0.1 mm |
| Thermal Conductivity | ± 5% |
| Weight Tolerance | ± 5% |
Types of Heat Sinks Explained
Heat sinks are generally optimal for electronic gadgets to control and release heat. They are of various categories depending on factors like flow, material, and orientation of the fins. Here are the two primary categories:
Active Heat Sinks
Active heat sinks are considered highly efficient. They are directly connected to the device’s power source and employ the forced convection technique, in which air or a liquid is circulated over the hot components to facilitate heat transfer.
Active heat sinks are normally used in GPUs and CPUs where heat dissipation is critical. Some designs also incorporate liquid cooling systems to enhance their cooling systems. The fans are usually mounted on the side or top of the heat sink and are in the cooling process.
Passive Heat Sinks
Passive heat sinks generally rely on convection currents to transfer heat from the component. Unlike active heat sinks, they do not require additional power or parts such as fans to operate. They depend on the convection currents created around the device to aid in the cooling process of the heat generated. While active heat sinks are better at cooling, passive heat sinks are cheaper and do not need any electrical power to function.
Moreover, these heat sinks are normally employed in devices that do not require high heat dissipation, such as microcontrollers, microprocessors, and chipsets. Due to their ease of use, passive heat sinks are used in power—and cost-sensitive applications.
Choosing between an active and passive heat sink is a major consideration in device design. Because of the cooling fans, active heat sinks do not require a large surface area for heat dissipation. Conversely, passive heat sinks require more surface area to radiate heat since there is no way of forcing air through the heat sink other than convection.
Heat sinks are mostly constructed from aluminum or copper when cooling electronic components. Below is the distribution of each material:
Copper
Copper is preferred for heat sinks because of its high thermal conductivity, approximately twice that of aluminium, and can range from 200 to 400 W/m-K. This high conductivity makes copper the best conductor of heat in the best way possible. However, copper is much heavier and more costly than aluminium. Moreover, it’s less flexible and malleable, so it can be made and molded in the desired form and shape as one would desire.
Aluminum
Aluminium is used for heat sink products because it is lightweight and affordable compared to other metals available on the market. However, its high thermal conductivity, about half that of copper, means it can not be used for heat transfer. Aluminium is easy to process, light, and can be produced as thin but sufficiently strong sheets; however, the heat transfer coefficient depends on the material’s thermal conductivity.
Designing Tips for Heat Sinks
Heat sink design is one of the most critical steps that has to be completed to guarantee proper thermal control in electronics. Here are key factors to keep in mind:
- Material Selection: The type of material used has a significant influence on the heat sink performance:
- Thermal Interface Materials (TIMs): TIMs insert themselves between the heat sink and the components, possessing relatively low thermal resistance to enhance heat transfer. Materials like mica are used because they are better conductors than air.
- Heat Sink Materials: Aluminum and copper are the most preferential materials for heat sinks. Aluminium is chosen for its low cost, low density, and ease of form, while copper has better heat transfer and can resist corrosion. When these metals are combined, they make one of the best heat sinks, a material used to dissipate heat.
The materials used in the heat sink can transfer heat, which would minimize the reliability of the device’s components, which are prone to heat damage.
Techniques Used in the Production of Heat Sinks
Usually there are three key manufacturing methods commonly used for creating aluminium heat sinks:
CNC machining is an advanced manufacturing technique that includes milling, drilling, grinding, and turning operations. This method offers flexibility since one can develop parts with certain design characteristics upto minimal tolerance as possible as +/-0.005’’. CNC machining is especially suitable for manufacturing heat sinks with complex and complicated shapes. These accurately engineered heat sinks are ideal for use where high thermal dissipation and intricate structure are mandatory. However, the accuracy and precision of CNC machining make it more costly than the other cutting methods.
Extrusion
Extrusion methods involve forcing the material, like aluminium alloys, through a shaped opening or die to achieve a desired cross-sectional profile. Extrusion offers affordability and effectiveness when it comes to producing heat sinks. The extrusion process is particularly well suited to creating specific heat sinks because it can easily form aluminum alloys such as 6063 with high thermal conductivity. However, one of the drawbacks of the extrusion method is the maximum width of the heat sinks that can be developed, which may limit the size of the heat sink.
Die Casting
Die casting entails placing aluminium alloy into a furnace, melting it, and forcing it into a mold under pressure. This method is very flexible in design, has good thermal properties, and is relatively cheap for large-scale production. Thermal castings are ideal for thickness and natural convection-based systems or applications. The die-casting process is particularly suitable for creating thin, strong, and complex heat sink geometries and is widely used in creating complex heat sink structures.
Heat Sink Structures
Let’s explore the structures of heat sinks by examining three distinct types: Some types of heat sinks include cold plates, pin-fin heat sinks, and plate-fin heat sinks.
Cold Plates
In today’s world, most electronic devices need sophisticated cooling techniques to meet the thermal challenges posed by high-power circuits. Cold plates, including liquid ones, are applied in high-power lasers, fuel cells, battery cooling systems, motor drivers, medical equipment, etc. These cooling systems cool a particular component by transferring heat from the said component to a circulating fluid. This medium transfers the heat to a distant heat exchanger, where the heat is released to the atmosphere or another liquid in a second cooling circuit.
Pin-Fin Heat Sinks
Pin-fin heat sinks can be described by an extrusion design in which a cluster of pins is provided. These pins, which may be cylindrical, elliptical, or square in cross-sectional shape, rise up or out from a central hub. Although the manufacturing cost of pin-fin heat sinks is relatively low, they are less effective than other heat sinks. Pin-fin heat sinks have lower heat removal capacity than other heat sinks and, therefore, are applied less frequently than, for example, fin heat sinks.
Plate-Fin Heat Sinks
Plate-fin heat sinks are made with straight fins that greatly contribute to the increase of the heat sink’s surface area. They improve heat dissipation. Their structure enables the heat to be conveyed away from the component efficiently, making it an efficient cooling system. Manufacturing methods of plate-fin heat sinks are diverse, and these heat sinks can be implemented in several applications. They are often applied to the outer surface of mechanical casings and covers and are one of the most straightforward and efficient means of cooling. They do not produce noise and require minimal power sources.
Conclusion
Heat sink design is critical in determining electronic devices’ efficiency and lifespan. A good heat sink design can significantly improve heat dissipation, reducing heat effects on the components. Therefore, it is important to differentiate between different types of heat sinks and their associated design parameters to develop an effective cooling solution.
Othala remains a valuable manufacturer for producing heat sink designs for the best performance. Our team of professional engineers will help you design heat sinks that meet your needs and requirements for many years. Whether you are developing the first sample or producing thousands of copies, Othanla offers accurate manufacturing and design improvements for your project.
