The ability to customize the look and feel of a mechanical keyboard is one of the most enticing parts of the hobby. For most hobbyists, personalizing a keyboard starts and ends with the most abundant component of all, the keycaps.
You have probably seen keycaps that vary in size, shape, and colour. Some may even be transparent or filled with a clear lacquer, containing a figurine inside. While style and look are very important for some mechanical keyboard enthusiasts, it’s equally important to know what material the keycaps are actually made of.
| ABS | PBT | POM | |
|---|---|---|---|
| Cost | $ | $$$ | $$$ |
| Texture | Smooth | Gritty/Grainy | Smooth |
| Shines over time | Yes | No | No |
| Wear speed | Fast | Slow | Slow |
| Yellows over time | Yes | No | No |
Keycap Materials
The vast majority of keycaps are made of plastic. However, you have probably seen materials used like wood, silicon, and even metal. In this breakdown, we’ll be focusing on the three main types of plastic that are used to form keycaps.
ABS, PBT, and POM.
ABS (Acrylonitrile Butadiene Styrene).
The most commonly used plastic for keycaps and keyboard casings. ABS is a thermoplastic, at a certain temperature, it becomes easy to mould and solidifies upon cooling. This makes it a perfect pliable material for injection moulding, the primary process for forming keycaps.
Form Factor
ABS is light-weight, tough, impact-resistant, and most importantly, low cost. These factors make it the primary material used for mass-producing consumer goods, including mechanical keyboards.
Manufacturers prefer to use ABS for double-shot moulding, which is the process of forming a keycap around a metal or plastic insert. This material is preferred as it is not as prone to shrinkage as other plastics may be. This is why you may see a keyboard composed of PBT keycaps with an ABS space bar, larger keys are simply too problematic to manufacture with other materials.
ABS keycaps feel much smoother compared to PBT or POM. For reference, LEGO is made of the same material, it’s a very slick and smooth plastic.
There are a few downsides to ABS plastic keycaps, overtime the keys will begin to appear shiny as a result of wear and tear.
This material is also susceptible to sunlight exposure, overtime lighter coloured keys will begin to turn yellow.
PBT (Polybutylene Terephthalate).
One of the hardest and most durable keycap materials, PBT is becoming the go-to material for high-quality mechanical keyboards. Unlike ABS plastic, PBT is more resistant to heat and chemicals. This means it won’t have the same yellowing problem as ABS keyboards, but it does make moulding keycaps a bit trickier.
The texture of PBT keycaps is a bit grainy or sandy in comparison to the smooth ABS keycaps. Overtime this texture won’t wear off, as it’s a property of the plastic. It is possible to find PBT keycap sets that have a smooth texture, however, the vast majority of sets are quite grainy. Since PBT does not wear down, it will not be prone to the “shine” that ABS keycaps have over extensive use.
PBT Drawbacks
There are some obvious drawbacks of using PBT plastic for keycaps, the main factor being cost. PBT is much more expensive than ABS plastic, which is why we only see it used on higher-end mechanical keyboards. Additionally, PBT plastic is more difficult to mould than ABS. It is prone to shrinking and warping, which makes working with the material difficult. This makes the double-shot moulding process particularly tricky and laborious, driving up the cost as a result.
There are some good benefits to the high melting point of PBT plastic. Most ABS keycaps have their legends laser-etched (burned), printed, or laser-engraved. These processes are subject to wear and tear and may fade over time. With PBT plastic, dye-sublimation is used to sink ink into the plastic, permanently staining the keycap and protecting the legend from erosion.
POM (Polyoxymethylene).
This material is rarely used in mechanical keyboard keycaps. Like ABS, POM is a thermoplastic that is slippery to the touch, however, it is much more durable and significantly harder. This material is commonly referred to by its brand name Delrin, the densest plastic used as a keycap material.
Cherry is one of the few manufacturers that use POM plastic on their mechanical keyboards, namely on the black keycaps for the G80 and G81 series. This material is wear-resistant, solvent-resistant, and low-friction. These qualities come at a high cost, which explains the rarity of the material. Legends on POM keycaps are primarily laser-engraved, which is prone to fade over time.
PVC (Polyvinyl Chloride).
A relatively inexpensive and hard material, PVC is the second most commonly used keycap plastic. Massive brands such as Logitech, Dell, and HP use PVC for its keyboards due to its low cost. Most PVC keycap legends are pad-printed or stickers, generally, they are poor quality and we would not recommend purchasing a keyboard with PVC keycaps.
Key manufacturing
Injection moulding
The primary process for manufacturing keycaps. Injection moulding delivers melted pliable plastic into a metal mould, forming a keycap. Once the plastic has cooled the keycap retains its rigidity and can be removed from the moulding.
(Warning, the video is loud)
Keycap compatibility
Keycaps are not universal, it’s important that you do your research to determine which aftermarket keycaps are compatible with your mechanical keyboard. Don’t make the mistake that we have made in the past, buying keycaps that don’t fit!
How do I know what material my keycaps are?
For this experiment, we would recommend using any spare key that comes with the purchase of your mechanical keyboard, as the resulting product may be deformed. Bring a pot of water to a boil, drop in your keycap for around 10 minutes. Measuring the temperature with a thermometer, ABS keycaps will begin to deform at 105 degrees Celsius. Remove the keycap and let it cool. If the keycap is now bent or deformed, the plastic is probably ABS. If it is not deformed, your keys are likely PBT.
Legend Printing
What are legends?
Legends are the letters, numbers, or symbols that are printed or moulded into keycaps. Legends can be a variety of colours and fonts, some keyboard manufacturers have the ability to print legends on the top, front, or side of the keycap. You may even see mechanical keyboards that are completely absent of any legends.
How are legends made?
There are a few different processes of forming legends, some are considered better than others due to their ability to last through extensive wear and tear. Lower quality legends such as pad printing are much cheaper than a highly reputable process, such as double-shot moulding.
Pad-printing is one of the most common ways of creating a legend, a printer is used to ink the symbols onto the keycap. This is a cheap and effective way of inscribing legends, it will quickly wear down and begin to fade.
Laser marking, a few different methods of laser printing exist for printing keycap legends. There is charring, foaming, colouring, and ablation. All of these methods are prone to fading and staining over time.
Charring, or etching, uses a laser to heat the plastic to a darker shade, this is generally only used on gray and white keycaps where the darkening is noticeable.
Foaming creates an exterior of miniature and hard bubbles, the bubbles created are white and so this process primarily used on black keycaps.
Colouring is the process of using a UV laser to burn away one of the plastic colourants, this exposes another colour as a result.
Ablation is probably the best method of laser printing. A laser is used to burn deep grooves in the surface of the keycap, these grooves can be left empty or can be filled with colouring.
Dye Sublimation
Dye sublimation is a process that uses heat to sink the dye colouring into the plastic keycap. The dye ink becomes part of the keycap and will last much longer than a printed or laser marked legend. Some limitations of this process are that its more expensive than lesser alternatives, and the dye must be darker than the colour of the actual keycap. If you’re looking for a durable and long-lasting keycap, this printing process is permanent and one of the best.
Double-shot
Double-shot injection moulding is the most expensive and complex legend printing process, but its also the best, and for good reason. Rather than printing or etching the legend into the actual keycap, the legend is pre-moulded as an insert. The rest of the keycap is then moulded around this insert, and physically becomes part of the key. As a result, the legend cannot be worn off, and manufacturers can create high contrast and vibrantly coloured legends.
Conclusion
Keycaps are an extremely important part of any mechanical keyboard build. With such a wide range of materials and manufacturing processes, its difficult to find the right keycap for your preference. We prefer PBT double-shot keycaps and would suggest that combination to anyone looking for quality long-lasting components.
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