Which PCB to choose
In custom mechanical keyboards, the PCB (printed circuit board) is the rigid board that holds the switches and electronics. Its thickness (commonly 1.6 mm or 1.2 mm) has a big impact on how the keyboard feels, sounds, and even how well parts fit. For example, most PCBs are about 1.6 mm thick by default, because this provides good mechanical strength so the board “does not flex, bend or break” under normal use. This matters to builders: choosing a thinner 1.2 mm board can make a lighter or slightly softer-feeling keyboard, while a 1.6 mm board will be stiffer and sturdier. Likewise, many modern PCBs offer flex cuts – little slots cut into the board – which deliberately allow extra give in the PCB.
What Is PCB Thickness and Why It Matters
PCBs are normally made out of FR-4 fiberglass, and the thickness is typically measured in millimeters. The standard thickness is about 1.6 mm. This thickness was chosen as a compromise of strength and cost: a 1.6 mm board is rigid and resists bending or flexing under normal pressure, so it provides a solid foundation for your keyboard. In contrast, a thinner 1.2 mm PCB is somewhat more flexible and occupies less space, which can be useful in ultra-compact or lightweight designs.
Thickness also affects compatibility with other components. Many keyboards and stabilizers are designed for a 1.6 mm board. Using a different thickness can misalign connectors or stabilizer pins. For example, if you try to mount stabilizers made for 1.6 mm onto a 1.2 mm PCB, the parts may not seat properly and could wobble or even damage the board. In short, PCB thickness matters for mechanical strength, fit, and the overall feel of the keyboard. A thicker board is stiffer and more stable, while a thinner board bends more easily but may need extra care in assembly.
1.6 mm vs 1.2 mm PCBs
As we said before, the two most common PCB thicknesses for keyboards are 1.6 mm and 1.2 mm. A 1.6 mm PCB is noticeably more rigid and durable: it can handle greater mechanical stress without warping or breaking. Typing on a keyboard with a 1.6 mm PCB generally feels very solid and stable. Because the board doesn’t flex much, the keys have a crisp, direct feedback (some builders describe it as a “thocky” feel). The durability of 1.6 mm also means it is less likely to crack or bend if you press hard. Additionally, most stabilizers and plate mounts are made for 1.6 mm, so parts tend to fit without extra modification. This thickness is also better at spreading heat, which is a factor in electronic reliability (though in a keyboard this is usually minor). The main drawbacks of 1.6 mm are that it’s slightly heavier and leaves no give in the case.
A 1.2 mm PCB is thinner and lighter by comparison. This can be an advantage in very compact or low-profile builds: it takes up less space and can make the overall keyboard feel a bit lighter. A thinner board also flexes more, so the keyboard can have a touch of extra “give” under heavy keypresses (a very slight springiness). However, this comes with trade-offs. A 1.2 mm board is less durable – it bends or stresses more easily and, in some cases, can crack if treated roughly. Many in the keyboard community note that 1.2 mm PCBs can feel a bit flimsier or “wobbly” if not properly reinforced. Compatibility can also be an issue: you often need stabilizer shims or pads to use 1.6 mm-designed stabilizers on a 1.2 mm board, or else the stabilizers may sit too deep and rattle. In summary: 1.6 mm boards give a firm, rock-solid feel and work with standard parts, while 1.2 mm boards give a slightly lighter, softer feel but require careful assembly and may not fit thicker components without adjustment.
What Are Flex Cuts and How They Work
“Flex cuts” are specially placed slits or slots cut into the PCB (and sometimes the plate) to let the board bend more easily. A flex-cut PCB uses these precise cutouts as built-in hinges, allowing parts of the board to move under pressure. In other words, the board is still made of the same material (often FR-4), but the cuts relieve stress so it can flex at those points. By contrast, a non-flex (rigid) PCB has no such cuts and remains completely solid and unbendable. In practical terms, adding flex cuts is a way to tune how much the keyboard flexes when you type – it intentionally softens the typing feel by letting the PCB flex under each keystroke.
Flex-Cut vs Non-Flex: Comfort, Sound, and Flex
Adding flex cuts to a PCB makes the keyboard feel softer and bouncier. The cuts allow each keypress to slightly bend the board instead of hitting a completely rigid surface. Builders who prefer a cushioned, springy feel often choose flex-cut PCBs. This generally feels comfortable for long typing sessions, as each keypress is less abrupt. However, some users find that too much flex can feel a bit mushy – the typing response isn’t as crisp as on a rigid board.
Flex cuts also change the sound of the keyboard. Because the board is no longer a perfect solid surface, it transmits more vibration into the case. As a result, keyboards with flex-cut PCBs tend to sound a bit louder and boomier. In fact, measurements show that flex-cut PCBs let more sound waves through, producing extra reverb and low-end bass in the typing sound. By contrast, a rigid PCB (no flex cuts) will produce a slightly quieter, more direct sound with less echo (some builders describe this as a “tight” sound).
In summary, flex-cut PCBs give a noticeably more flexible typing feel – keys feel cushioned and springy – and they amplify deeper tones in the sound. Non-flex (rigid) PCBs keep the board stiff, so keypresses feel very firm and click directly; they tend to yield a cleaner, less resonant sound. The choice comes down to preference: flex cuts add comfort and squish at the cost of a softer (sometimes mushier) feel and a louder, bassier sound, while a solid PCB is snappier and quieter but feels very rigid.
Conclusions
1.6 mm vs 1.2 mm PCBs
• 1.6 mm PCB: Very stable and durable – resists bending under force. Feels firm and solid, giving crisp key feedback. Works with standard components without extra shims.
• 1.2 mm PCB: Lighter and slightly thinner in the build; can allow a touch of flex for a softer bottom-out. Often a bit cheaper to produce in volume.
Flex-Cut vs Non-Flex PCBs
• Flex-Cut PCB: Provides a softer, springy feel by letting the PCB flex under each keystroke. Can reduce harsh impact and absorb some vibration
• Non-Flex (Rigid) PCB: Gives a very crisp and direct typing response, as the PCB doesn’t give at all. Usually quieter and more controlled sound.
Each option has trade-offs. A 1.6 mm rigid PCB with no flex cuts is a classic choice for a very solid, stable keyboard. A 1.2 mm flex-cut PCB, on the other hand, will maximize bounce and dampening in the build. New builders often choose a default 1.6 mm non-flex design for guaranteed stability and ease of assembly, while more advanced users might experiment with 1.2 mm or flex cuts to fine-tune feel and acoustics in their custom keyboards.
But in the end, like everything in this hobby, all depends on your personal preference. The best way to choose is to try.
I hope you have an happy typing!!