What does foam do in keyboards?

When you type on a mechanical keyboard, its hollow plastic or aluminum casing acts much like a drum. When you press a key, this vibration resonates in the hard empty spaces inside the chassis and you hear a metallic echo or hollow sound. It’s like putting your keys or phone on a table in an otherwise empty room. These noises can be loud and even make an expensive keyboard sound cheap and distracting – one of the many things to know before getting a mechanical keyboard. This is where a practical cushioning keyboard foam comes in.

Putting a layer of foam inside your mechanical keyboard is like adding sound-absorbing foam panels to the inside of a music recording studio. The foam attenuates the sound so that it is more pleasant, with a deeper tone, thus avoiding high-pitched echoes. Mechanical keyboard enthusiasts generally call this a “shot.” Foam also makes your keyboard stronger and more stable. The magic lies in how this layer of soundproofing filters out these annoying frequencies.

Even though it’s just a thin layer of foam, it acts as a barrier that traps nasty high-frequency sounds without blocking that beloved bass shock. Foam is one of the most popular and profitable mods in the field of mechanical keyboard modding. And whether your goal is to create a keyboard that’s fun to use in a quiet office or enjoy richer sound while working from home, this simple upgrade delivers great results with little effort, no matter what color keyboard switch you ultimately choose.

You have several options for where to place your foam and what material to use, and different options give different results. There are two placement options: case foam and plate foam. The case foam sits at the very bottom of the chassis, underneath all other components; this option is ideal for neutralizing these hollow sounds. The plate foam sits between your keyboard plate and the PCB (printed circuit board). This option is great if you want to get rid of those high-pitched harmonic sounds and lower the pitch a bit.

There are several types of foam, but the most common and popular is PE foam. Generally speaking, PE attenuates noise well without disturbing the switches. Plus, it gives you a creamy or even pop sound. IXPE is also good; it is PE bonded but anti-static and best placed directly against your circuit board. Beyond those two, you can opt for Poron and EVA foam, which are denser but also absorb sound much better if you want a deeper, less popping sound.

The type and location of foam are just a few of the many variables at play when it comes to tuning the acoustics of your mechanical keyboard. Thicker layers mean a more discreet board, which is ideal if you use yours at work. Alternatively, a thinner layer rounds out the edges of higher frequencies without blocking the sound of your switches. And really, experimenting a little with foam types and placement is just one of the fun reasons why enthusiasts choose a mechanical keyboard.