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CSE Keyboards

03 / 06 · Keycaps

Keycaps: materials and profiles

What difference the material makes (ABS, PBT, POM, resin, aluminium), how the OEM, Cherry, SA, DSA and XDA profiles are shaped, and how long legends last depending on how they are applied.

Materials

If the switch is the key’s “engine”, the keycap is its “bodywork” and “steering wheel”: the part you actually touch. It is the last link in the mechanical chain, so it strongly shapes the final feel and sound.

Choosing keycaps matters as much as choosing switches, and it affects three things: how they feel, how they sound and how well they keep their looks over time.

The material sets the keycap’s density, texture, weight, sound and resistance to chemical and mechanical wear.

ABS

Acrylonitrile butadiene styrene, the most common plastic for keycaps, especially on off-the-shelf (pre-built) keyboards.

  • Easy to injection-mould thanks to its lower melting point
  • Vivid colours and precise double-shot legends with crisp edges
  • The natural oils on your fingers degrade the surface, which over time develops an unsightly “shine”
  • Sunlight (UV) can turn it yellow
  • Being less dense than PBT, it sounds higher-pitched and sharper

PBT

Polybutylene terephthalate, a superior plastic preferred by enthusiasts. It is denser and stiffer than ABS.

  • Its semi-crystalline structure makes it highly resistant to solvents: skin oils do not affect it
  • Keeps its matte, slightly rough texture for much longer
  • A fuller, deeper sound (“thocky”), thanks to its density and stiffness
  • It shrinks more as it cools after moulding, so long pieces such as the spacebar are hard to make perfectly straight
  • Double-shot moulds are more complex

POM

Polyoxymethylene, also known as Delrin. A niche material.

  • Very smooth to the touch, thanks to its very low friction
  • Dense and durable
  • A distinctive, more muffled sound

Epoxy resin

Used for one-of-a-kind artisan keycaps.

  • Practically unlimited creative freedom

Aluminium

A premium material, CNC-milled.

  • A premium, cool feel
  • A very high-pitched sound

From the thesis, chapter 2.2

Profiles

Sculpted profiles (OEM, Cherry, SA) change height and angle from row to row; uniform ones (DSA, XDA) have the same shape on every key.R1R2R3R4Sculpted: height and angle change per rowUniform: the same key on every rowOEMcylindricalCherrycylindricalSAsphericalDSAsphericalXDAspherical
Sculpted profiles (OEM, Cherry, SA) change height and angle from row to row; uniform ones (DSA, XDA) have the same shape on every key.

Sculpted profiles

OEM

The most common profile: tall, with a concave, cylindrical top.

Cherry

Similar to OEM but lower. Many see it as the gold standard for long-term comfort, because it asks less movement of the wrist.

SA (Spherical All-rows)

A tall, “retro” profile with a deep spherical top. Its aggressive sculpting feels distinctive but can take some getting used to.

In sculpted profiles each row has its own height and angle, following the natural arc of the fingers to cut distance and effort. In uniform profiles every key has the same shape and height.

Uniform profiles

DSA

Medium height, spherical top.

  • Every key is interchangeable, which is essential for non-standard layouts (ortholinear, for example)

XDA

Like DSA, but slightly taller and with a larger, flatter top.

  • Preferred by some for its stable feel

From the thesis, chapter 2.2

Legends: how they are applied

The method used to put letters and symbols (legends) on the keys directly decides how well they stand up to wear.

Four methods, from the most superficial (pad printing) to the most durable (double-shot).Pad printingink as a thin layeron top of the surfaceLaser etchingtop coat removed,plastic below exposedDye-sublimationink diffused into thetop of the plastic; onlydarker than the keycapDouble-shottwo plastic shots: thelegend is its own piecethrough the keycap
Four methods, from the most superficial (pad printing) to the most durable (double-shot).

Pad printing

The legend is transferred with a silicone pad.

  • The cheapest method
  • Very low durability

Laser etching (ablation)

A laser removes the top layer (e.g. black paint) to expose the plastic underneath, often translucent for RGB lighting.

  • A surface method, vulnerable to abrasion over time

Dye-sublimation (dye-sub)

Heat turns solid ink straight into a gas, which diffuses into the plastic and becomes part of it. It works best on PBT.

  • The legend can never wear off, because it is not a surface layer
  • It can only add colour, so it only works for legends darker than the keycap

Double-shot

The keycap is made of two plastic parts moulded one after the other in different moulds: the first shot forms the legend, the second forms the body of the key around it. It is considered the highest-quality method.

  • The legend is a solid piece of plastic, so it cannot wear off
  • Perfect, lasting contrast, e.g. white legends on black keys

PBT double-shot, Cherry profile

The thesis concludes that PBT double-shot keycaps in Cherry profile are a de facto industry standard: chemical and mechanical durability, proven ergonomic comfort and a pleasant sound.

From the thesis, chapter 2.2

In the shop

Written from Ștefan-Emanuel Ciupitu’s bachelor thesis “Wireless multifunction keyboard using the nRF52840 module” (Suceava, 2025).