What’s the best heat sink manufacturing process?

1. Extrusion

Extrusion involves pushing material through a die matching the desired shape. Extruded aluminium heat sinks are some of the most common heat sink options sold today for several good reasons:

• Aluminium is plentiful and easy to work with
• Extrusion is a cost-effective process for creating complex cross-sections
• This method offers easy opportunities for customisation
• Extrusion limits dimensional stresses during fabrication, reducing the brittleness of the material

The primary disadvantage of using extrusion in heat sink manufacturing is the hard limits on the product’s width. It is common to find extruded heat sinks for sale by the foot, but limitations on the other dimensions may hold your product back. The performance of extruded heat sinks can range from low to high.

2. Skiving

The process of fabricating skived heat sinks begins by extruding a long piece of solid metal – usually copper – into a rectangular shape. The metal block then passes beneath an angled blade, which creates thin slices into the material and bends them into heat sink fins. Here are the reasons some engineers say this is the best method for heat sink manufacturing:

• Skiving offers a higher degree of design flexibility than other methods
• Projects that require a very high fin density are an excellent match for skiving
• The higher surface area creates better performance during heat dissipation
• This process requires a shorter lead time than other methods

The chief drawback of this method is the end product is usually weightier than one produced using other methods. Skived heat sinks are also more direction-sensitive than others. This method also requires specialised machinery and training others do not.

3. Bonding

Bonding is another common heat sink manufacturing technique. It is generally used when the intended dimensions of the heat sink exceed the manufacturing capabilities of other methods. There are other advantages as well:

• Facilitates the creation of oversized heat sinks
• Allows the fin and base material to be different
• Combines a copper base with aluminium fins to boost thermal performance

Heat sinks with bonded fins come at a cost premium, but they usually offer improved functionality compared to many extruded designs. Using copper in tandem with aluminum provides performance improvements with a noticeable but ultimately modest weight increase.

4. Stamping

Situations that have minimal heat dissipation requirements often call for stamped heat sinks. Here are the reasons to choose this method:

• It is perfect for low-power electronic devices, like IoT devices
• Stamping is a highly cost-effective process
• The process can be automated relatively easily

The only real drawback of stamping in heat sink manufacturing is the generally low performance these products offer. Again, this may be a feature rather than a bug – stamping is cheap and scales easily. Depending on your design, this could be the ideal method for fabricating a heat sink.

Automating this process in your factory or machine shop could be a good management decision. Identifying areas where defects carry higher risks can help pinpoint opportunities for automation. Heat sinks failing is one potentially catastrophic eventuality that stamping, and automation could reduce or avoid.

5. Machining

Some of the most complicated part geometries can be obtained using conventional machining equipment you could find in most machine shops, including drills, mills, lathes, and other CNC machines. Some of the benefits of machined heat sinks include:

• CNC machining provides a good degree of design flexibility
• Machining a heat sink also yields a product with almost unrivaled thermal conductivity
• Machined components make sense for low-volume, potentially luxury-tier goods emphasising performance, longevity and durability over cost considerations

Manufacturing heat sinks this way is typically more expensive than other methods, partly because some instruments require time and attention to calibrate. However, the necessary time and expertise could be worth it for the other benefits. Machined components bring both real and perceived value to the end product because of the time and skill needed.

6. Forging

The forging process – involving the compression of copper or aluminum under high pressures – yields capable heat sinks with some specific and appealing advantages:

• Unlike extruded heat sinks, forged heat sinks provide much greater heat-dissipation surface area by packing more fins into the same amount of space
• Forging can be a faster process with a higher yield, especially compared to die casting or extruding. It offers a single-step operation
• The performance of forged heat sinks can be mid-range to high at a relatively low cost

The forging process provides fewer opportunities for design complexity, nuance or customisation compared to some of the other methods listed here.

7. Die Casting

Along with extruded heat sinks, die-cast heat sinks have historically been the favored choice. Here are some reasons why:

• The simple process of pouring liquid metal into a mold supports a wide range of design possibilities, many of which aren’t possible through extrusion or other methods
• Die casting can produce aluminium, copper, or zinc heat sinks
• The process is relatively inexpensive but yields a high rate of production

Die-cast heat sinks provide other mechanical properties that make them a favorable choice, including higher dimensional stability than, for example, skived heat sinks.

8. 3D printing

Additive manufacturing – or 3D printing – is probably the most talked-about manufacturing method today, including for heat sinks. In particular, heat dissipation requirements in the lighting industry are highly specialised and require intricate designs for aesthetic value and performance. When it comes to heat sinks for lighting, electronics and other applications, 3D printing:

• Yields perhaps the most significant design flexibility of any heat sink manufacturing method. Components created by 3D printers can have hollows, channels and filigrees not achievable using conventional tools and techniques
• Supports biomimicry in heat sink design. A team of doctoral students from Purdue University proved this by 3D printing highly efficient heat sinks mimicking the tiny porosity of shark skin
• Helps reduce material use. As the Purdue team demonstrated, coupling 3D printing’s fast prototyping with simulation software can yield novel designs that minimise the material required to provide the desired result

In fact, the shark skin-inspired designs handily exceeded the students’ expectations in both simulations and real-world trials. 3D printing could play an ever-larger role in heat sink fabrication and other areas of lighting, electronics, aerospace, and energy infrastructure design in the coming years.

How to choose the right heat sink manufacturing process

Heat sinks require careful consideration. Manufacturers today are more concerned than ever with turnaround times and product longevity amid shortages and supply-chain disruptions. With that in mind, review this article to see how your manufacturing choice will influence your design and enterprise flexibility down the road – along with the product's capabilities in which the heat sink resides.