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What are Poron & PET Pads in Mechanical Keyboards? A Practical Guide to Foam, Pads, and Acoustic Tuning

Poron and PET pads are two popular materials hobbyists and keyboard builders use to tune the sound, reduce rattles, and improve the typing feel of mechanical keyboards. This guide explains what they are, how they differ, where to place them, and how to use them for better keyboard acoustics and feel. Quick Definitions: Poron vs PET Pad Poron is a microcellular urethane foam known for consistent compressibility, excellent shock absorption, and long-term resilience. In keyboards, Poron foam is commonly used as case foam, gasket material, or switch/plate foam to reduce hollowness and improve low-frequency damping. PET pad (polyethylene terephthalate) refers to thin, dense polyester sheets or pads used under the PCB or between the plate and case. PET pads are usually stiffer than Poron and are prized for controlling high-frequency ring and decreasing harsh overtones without over-dampening the keyboard. Why Builders Use Poron and PET Pads Acoustic tuning: Change the keyboard’s sound signature — from hollow and pingy to deep and thocky. Vibration damping: Reduce plate and case resonance that causes unwanted ringing. Stabilizer and switch support: Decrease wobble and improve keypress consistency. Shock absorption: Prevent damage and reduce impact noise from heavy typing. Where to Install Poron & PET Pads Placement matters. Typical locations include: Case foam: Large Poron sheet between the inner case and PCB to absorb low-frequency resonance. Plate foam / switch foam: Thin Poron or PET cutouts between the plate and PCB to prevent switch wobble and reduce ping. Under-PCB pads: PET or Poron pads under screw posts or at PCB corners to isolate vibrations from the case. Between PCB and back cover: PET pad to dampen high-frequency ringing while preserving snap. Gasket / mounting points: Small Poron strips used in gasket mounts for cushioning and compliance. Poron vs PET Pad — Material Comparison Feature Poron PET Pad Density Soft to medium; compressible Medium to stiff; thin and dense Damping Excellent for low-frequency, shock absorption Better at controlling high-frequency ring and sharp overtones Longevity High — maintains properties over time High — stable and non-absorptive Typical use Case foam, gasket, switch foam Under-PCB pads, thin plate damping, between layers How Poron & PET Pads Change Keyboard Sound Sound signature is a combination of keycaps, switches, plate material, case material, and internal damping. Using Poron typically adds warmth and reduces harshness — many builders describe the effect as making the keyboard more thocky. PET pads reduce the high-frequency ring and make the sound cleaner without killing the per-key snap. Common sound goals and recommended materials: Reduce hollow ping: Add thicker Poron case foam. Keep snappy but reduce shrill tones: Add PET pad under the PCB near the center or plate contact. Balance low and high frequencies: Combine Poron case foam with thin PET strips at screw posts or between plate and case. Installation Tips & Best Practices Measure and cut precisely: Use a sharp hobby knife or scissors and measure the PCB and screw posts carefully. Layer strategically: Start with one thin layer then add more if needed — small changes have big acoustic effects. Test after each change: Reassemble and type to hear differences. Keep a log of thicknesses and positions that sounded best. Avoid over-dampening: Too much foam can deaden the keyboard and remove desirable attack tones. Use adhesive-free solutions when possible: Some PET pads come with adhesive; use low-tack tape if you want reversibility. Thickness, Density, and Selecting the Right Product Poron is typically available in thicknesses from 0.5mm to 6mm for keyboard use. For case foam, 2–4mm Poron is common. PET pads are usually thin (0.2–1.0mm) but dense. When selecting, consider: Keyboard case volume — larger cases benefit from thicker case foam. Plate material — aluminum plates resonate differently than polycarbonate; pair materials thoughtfully. Your sound preference — warm and muted vs lively and snappy. Common Mods Combining Poron and PET Advanced builders often mix materials: Poron case foam + PET pad under the PCB to balance low and high frequencies. Poron gasket strips at mounting posts with PET isolation pads at screw points. Poron switch foam with thin PET strips near stabilizers to control rattle while keeping tactility. FAQ — Frequently Asked Questions Will Poron or PET make my keyboard quieter? Yes — both reduce different types of noise. Poron reduces low-frequency boom and impact noise. PET pads reduce high-frequency ring. Use both for a quieter, well-balanced sound. Can I use both together? Absolutely. Combining Poron and PET pads is a common and effective strategy for fine-tuning sound and feel. Does thickness matter? Yes. Start thin and incrementally increase thickness. Small changes yield noticeable differences in acoustic characteristics. Are these mods reversible? Yes, if you avoid permanent adhesives. Use removable tape or non-permanent adhesives for experimentation. Whether you’re building a custom mechanical keyboard or modding a prebuilt board, Poron and PET pads are essential tools for acoustic tuning, vibration damping, and improving the typing feel. Experiment with placement, thickness, and layering to find your perfect sound signature.