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The Complete and instructive Guide to Heat Sinks

Heat sinks are the coolest component in the manufacturing world. Seriously—despite their name, the entire purpose of these is to redirect heat from a machine or electrical component to keep them cool and from burning out.

How do they achieve this, though? What makes them tick?

If you want to become a heat sink expert, or at least learn enough about them to get your foot in the door, then you have come to the right place.

What Are Heat Sinks?

Heat sinks are critical for any machine that uses electrical wiring, electrical component, microchip, or anything else that naturally gives off heat. In the modern world, that covers pretty much everything.

If you are at least somewhat familiar with the term “heat sink,” then you probably associate it with either laptop, desktop computers, CPUs, or manufacturing. Obviously, there is a huge difference in size for these kinds of parts, but they all rely on heat sinks for thermal regulation.

In laptops or PCs, and other electronics, they do this by circulating heat from the CPU or microchips. Machines in mass production factories and warehouses usually use them to redirect hot air from electrical components and wiring.

These are not the only machines that are used, though. You can also find them in refrigerators, cell phones, monitors/TVs, copy machines, automobiles, lighting, LEDs, internet cable and wireless transmission, and certain types of lasers.

Regardless of their use, though, their purpose is the same: redirect heat from the heat source without adding stress to an overburdened system

How Do They Work?

If you can think back to your K-12 science classes, you might remember that heat transfer occurs via radiation, convection, or conduction. Radiation generally applies to air and light waves. Convection happens in or because of water. That leaves conduction for solid materials like heat sinks.

Conduction happens any time that two solid objects with different temperatures contact one another. For example, setting a hot pan on a cool stove-top will cool the pan and heat the stove’s surface. If the pan is significantly hotter than the stove, then the pan won’t lose as much heat. The stove, on the other hand, will gain much more.

If you’re still a bit confused, try thinking about a heat sink like a car’s radiator, as suggested by this article. In a car, the radiator reroutes heat from the car’s engine to keep the car running. It’s important to note that this only works because the radiator expels the heat it absorbs.

Heat sinks work the same way. To ensure that neither the machine it is in nor itself overheats, that heat sink transmits or transfers the heat generated by the heat source through the heat sink to the surrounding cooler air. Heat sinks basically increase the surface are significantly that contacts the cooler air

A “passive heat sinks use the natural airflow created by the heat while active heat sinks some movement of air sometimes using a fan. While the heat sink itself absorbs the heat from another part of the machine from the heat source, the movement of air shoots that heat elsewhere and, subsequently, cools down the heat sink.

Heat Sink Materials

Traditionally most heat sink manufacturers use one of two materials: copper or aluminum. Copper has a higher thermal conductivity than aluminum, but it is also heavier, a more expensive material and cannot be formed in an extrusion. For these reasons, it’s pretty safe to say that the best heat sink material is aluminum.

Although an aluminum heatsink extrusion is not quite as conductive as copper heatsink on its own, it has more than enough additional benefits to make up for it. From a radiation standpoint, aluminum is typically brighter than copper, meaning that it is better at reflecting heat from light sources. This is true even for unpolished aluminum. Also, aluminum can be anodized in a multitude of colors.

Aluminum is inexpensive to manufacture to form an aluminum heat sink extrusion, especially in comparison to copper. It is also incredibly lightweight and easy to manipulate. Both factors make aluminum ideal for larger and custom-configured aluminum heat sink extrusion. These custom configurations are designed from extruded aluminum.

The main functionality of heat sinks depends on the fin arrangement. They are most effective when they cover the greatest possible surface area, so manufacturers design them with multiple layers (aka fins). These fins can use a pin, straight finned extrusion, or flared aluminum heat sink extrusion configurations.

Each of these configurations has its pros and cons. When the airflow is limited, a pin fin heat sink is the most common on the market, providing more surface area for the standard degree of heat transfer.  As the heat requirements increase, the fined aluminum heat sink extrusion can offer more economical and more configurations to transfer the heat better.  The configurable design of the fins is the best overall for both performance and energy cost. for more extensive deception on types and materials of extrusions take a look here.

Forged Pin Heat Sink
Forged Pin Heat Sink
Aluminum extruded fin heat sink
Aluminum Heat Sink Extrusion Finned Heat Sink
Skived Copper Sink
Skived Copper Heat Sink

Do All Machines or Electrical Components Fit These Standard Fin Configurations?

No, so this is where customization and aluminum heat sink extrusions come into play. Unlike copper, aluminum can be extruded (aka stretched and manipulated) during manufacturing to form more complex fin designs.

Manufacturers can also use aluminum heat sink extrusion to fit additional parts like heat pipes, liquid cooling piping, chassis, and spreader bars.

Generally, these parts are made of the more traditional copper. Copper is not nearly as easy to stretch or format, though, meaning that manufacturers have to use multiple sheets of copper to design each piece then heat those pieces to mold them together.

This creates excessive waste and can cost a lot of time. By using extruded aluminum, manufacturers can easily mold the base heat sink part to fit any additional components. It also cuts down on copper waste, which is both expensive and difficult to reuse. 

For a more comprehensive description of the differences between copper and aluminum heat sinks, see here.

Large Anodized Aluminum Heat Sink with Copper Heat Pipe
Large Aluminum Finned Sink with Liquid Cooled Copper Heat Pipe

Ionthis Inc.

As one of the best start-to-finish manufacturers, we are well equipped to answer any question you have or point you in the right direction. More importantly, we are always ready and willing to teach you how to be cool.

If you want to learn more about heat sinks, extrusions, sheet metal, or custom fabrication, check out Ionthis Inc.

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