The PE Foam Mod: How to Do It and What to Expect
By Jordan Marsh . 10 min read . Updated June 2026
The PE foam mod is one of the most recommended beginner sound mods in the hobby because it is cheap, reversible, and genuinely effective on most boards. You need a sheet of KBDFans PE Foam Switch Pad , a hot-swap keyboard, a switch puller, and about an hour. The result is a noticeably rounder sound that pushes the keystroke profile from bright and clacky toward the deeper tone that enthusiast builds aim for. This guide covers the materials, the process, and what to realistically expect from the change.
The short answer
Place PE foam between the PCB and plate after removing all switches. Cut the foam sheet to your PCB dimensions with scissors, punch or poke switch holes to match each switch position, then reinstall the switches through the foam. The result is a rounder, more absorbed keystroke sound often described as thocky rather than clacky.
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What the PE foam mod actually does
PE foam sits in the space between the PCB and the plate, the two layers that sandwich your switches in a tray-mount or top-mount keyboard. The foam shortens the acoustic path the keystroke sound travels before hitting the case, absorbing high frequencies and producing a rounder, more muted tone.
The effect is most audible on hollow plastic cases where the PCB resonates against the case interior. It is less dramatic on keyboards with thick aluminum cases or gasket mounts that already dampen sound naturally. Before buying materials, tap the bottom of your keyboard. If it rings or has a hollow sound, the PE foam mod will be more effective.
The PE foam mod pairs well with the tape mod. Apply a few layers of masking tape to the back of the PCB before adding PE foam and the combination noticeably changes the sound signature.
What you need
The KBDFans PE Foam Switch Pad sheet is the standard material. It cuts cleanly with scissors and comes in a large enough sheet for most 60 to 75 percent boards. For a full-size board, you may need two sheets. The NovelKeys Keyboard Sound Dampening Kit includes both PE foam and case foam if you want to do both mods in one session.
You also need a switch puller to remove all your switches without bending pins. If you plan to lube the switches at the same session, have Krytox GPL 205 Grade 0 Switch Lubricant and the KBDFans Switch Opener and Lube Station Kit ready. Combining the lube session with the foam mod is the most efficient use of the time you spend with the board open.
Optional: Deskeys Switch Films can go in during the same session for a complete mod stack.
KBDFans PE Foam Switch Pad
Pre-cut or sheet PE foam for the PE foam mod, placed between PCB and plate to change sound from clacky to rounded and absorbed.
NovelKeys Keyboard Sound Dampening Kit
Bundle of case foam, PE foam, and dampening sheets sized for common keyboard layouts from 60 percent through TKL.
KBDFans Switch Opener and Lube Station Kit
A beginner-friendly bundle of switch opener, lube station with 30-switch capacity, brushes, and a stem holder.
Step 1: Remove all switches
Use a switch puller to remove every switch from the board. Place switches in a tray in their original positions if you plan to return them without sorting. If you are lubing at the same time, this is when you start the lube station.
On most hot-swap boards, the PCB is visible once the switches are removed. Check whether the plate is attached to the PCB or separate. In most tray-mount boards the plate sits above the PCB with the switch pins passing through both. The foam goes between the PCB top surface and the plate underside.
Step 2: Cut the foam
Lay the PCB flat on the foam sheet and trace its outline lightly with a pencil or marker. Cut along the outline with scissors. The foam should match the PCB footprint closely but does not need to be perfect.
For the switch holes: hold the foam over the PCB and mark each switch position, then use scissors, a hole punch, or a sharp pencil to create openings at each switch location. The holes need to be large enough for the switch pins to pass through. On a 65 percent board you are making roughly 68 holes.
An alternative: some builders use a soldering iron tip to quickly melt switch-size holes through the foam rather than cutting each one. This is faster but requires ventilation and a steady hand.
Step 3: Place the foam and reinstall switches
Lay the cut foam over the PCB, aligning the switch holes to the PCB switch positions. The foam should sit flat with no buckles or folds. If it bunches at the edges, trim slightly until it lays flat.
Reinstall each switch by aligning the pins through the foam hole and into the hot-swap socket. Press firmly until the switch seats fully. Work row by row so you can verify foam alignment before closing everything.
If you are doing case foam at the same time with the NovelKeys Keyboard Sound Dampening Kit , add it to the case interior before closing the board.
NovelKeys Keyboard Sound Dampening Kit
Bundle of case foam, PE foam, and dampening sheets sized for common keyboard layouts from 60 percent through TKL.
What to expect from the result
Type on the board before and after if you can, or record a short audio clip. The change is real but takes a frame of reference to fully appreciate. Most builders describe the modded sound as thocky, shorter, and more absorbed versus clacky, longer, and brighter.
The foam mod will not transform a hollow $30 board into an endgame keyboard. It will make that board sound noticeably better than it did. On a mid-range board with a good case, it can be transformative. Pair the foam mod with lubed Gateron G Pro 3.0 Yellow Linear Switches switches and lubed stabilizers and the combination is a significant upgrade.
The Mechanical Keyboards Tempest Mod Tape Sheet tape mod adds a final layer of PCB dampening. Do it last, after the foam is in place, by applying tape to the back of the PCB before the case bottom closes.
Gateron G Pro 3.0 Yellow Linear Switches
Factory-lubed linear switches with a smooth, consistent travel and a 35g actuation weight. The most recommended budget linear for first builds.
Mechanical Keyboards Tempest Mod Tape Sheet
Masking tape sheet specifically cut for the tape mod on common PCB sizes, the free mod done in a box.
Featured in this guide
KBDFans PE Foam Switch Pad
Pre-cut or sheet PE foam for the PE foam mod, placed between PCB and plate to change sound from clacky to rounded and absorbed.
NovelKeys Keyboard Sound Dampening Kit
Bundle of case foam, PE foam, and dampening sheets sized for common keyboard layouts from 60 percent through TKL.
Mechanical Keyboards Tempest Mod Tape Sheet
Masking tape sheet specifically cut for the tape mod on common PCB sizes, the free mod done in a box.
Stupidfish Keyboard Carry Case Foam Insert
Dense case foam for keyboard cases, sold in sheets that fit between the PCB bottom and the case interior to reduce resonance.
Krytox GPL 205 Grade 0 Switch Lubricant
The community standard linear switch lube. Thick, stable, and effective. Applied thin, it transforms budget linears into smooth daily drivers.
Deskeys Switch Films
Thin TPE films placed between switch top and bottom housings to reduce wobble, improve consistency, and refine sound.
Gateron G Pro 3.0 Yellow Linear Switches
Factory-lubed linear switches with a smooth, consistent travel and a 35g actuation weight. The most recommended budget linear for first builds.
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FAQ
Frequently asked questions
Is the PE foam mod reversible?+
Yes. Remove all switches, lift the foam sheet out, and reinstall the switches. There is no adhesive involved and nothing is permanently altered. On a hot-swap board the whole reversal takes less than 30 minutes.
Do I need to do the PE foam mod and case foam mod together?+
Not required, but combining them is more effective. The PE foam mod changes the sound between the PCB and plate. Case foam changes the resonance of the case body. Together they address both major sound sources. If you can only do one, PE foam has the more audible impact on most budget boards.
Will the PE foam mod affect typing feel?+
Very slightly. Some builders report a marginally firmer bottom-out feeling, as if the keyboard is a fraction stiffer. Most people do not notice it without a direct comparison to the same board without foam. The sound change is far more noticeable than any feel change.