In other words, the switch plate must be fixed to keep the distance between the plate and the PCB constant.
Considering the mechanism, capacitive keyboards—much like magnetic ones—also need to maintain a constant distance between the switch support surface and the PCB.
Therefore, it’s difficult to adopt a mount structure where the switch plate moves freely relative to the PCB, which likely results in a more fixed design.
While the detection principle for key inputs differs from magnetic types, they share the need for a stable positional relationship between the switch’s moving/detection mechanism and the PCB.
REALFORCE and HHKB Professional address this constraint in different ways: the former uses a metal plate, while the latter uses an integrated resin upper housing.
Even though the structures differ, they are the same in that they fix the switch support surface so it doesn’t move relative to the PCB.
In this column, I’ll explore these points while looking at official explanations.
If you don’t care about quality, you can buy a keyboard very cheaply.
On the other hand, the keyboards mentioned here are all quite expensive—the kind of items you can’t buy without some serious consideration.
Or, depending on the model, they could even be a “keyboard for life.”
There probably aren’t many people who can just drop that kind of money on a whim.
That’s exactly why I think it’s crucial to understand what the typing feel is like and how it’s achieved, so you don’t end up with any regrets.
It’s a bit of a stretch to claim a typing feel is “supreme” without knowing how it differs from others.
Maybe you like the feel of capacitive switches, or maybe you prefer the gasket mount feel of mechanical keyboards.
It’s a matter of preference, and any choice is valid.
But when you think about *why* that typing feel is the way it is… keyboards become even more interesting.
This might get long, but bear with me for a bit.
What is “Typing Feel”?
For our purposes, let’s define typing feel as “the sensation felt at the fingertips when a switch is fully pressed.”
In other words, I’m using “typing feel” here to describe the sensation of “bottoming out.”
Many elements make up the typing feel: the input mechanism like the key switch, the plate material, sound-dampening foam, the mounting method, the case, the keycaps, and so on. These factors interact in complex ways to create the keyboard’s unique feel.
Among these, the “switch plate mounting method” and “its material” carry relatively heavy weight.
This article mainly discusses how the “chosen input mechanism” might structurally limit the “switch plate mounting method,” suggesting that the input mechanism itself might largely determine the “base of the typing feel (mounting method).”
Mounting Methods for Magnetic and Electrostatic Capacitive (EC) Keyboards
Even for keyboards using “electrostatic capacitive” switches—which are practically synonymous with “high-end keyboards” in Japan—the mounting method may be limited to some extent, just like with magnetic switches.
Let’s take a look at this.
In the capacitive method, a conical spring is placed inside a rubber dome.
When a key is pressed, the conical spring deforms, and the resulting change in capacitance is read by the PCB.
Image: PFU Official “Structural Diagram of Electrostatic Capacitive Non-contact Method”
This input mechanism mainly consists of the following parts:
Slider
Housing that holds the slider
Rubber dome
Conical spring
PCB-side electrodes
The “slider” here is similar to the “stem” in a mechanical switch.
If the surface supporting the slider sinks relative to the PCB, the positional relationship between these parts changes.
Therefore, in the capacitive method, it’s considered necessary to stabilize the distance between the slider support surface and the PCB.
For the sake of clarity in this article, I’ll refer to this slider support surface as the “part corresponding to the switch plate.”
Thus, it’s fair to say that sensing the change in capacitance assumes the distance between the switch plate and the PCB is kept constant to read the input signal accurately.
In short, we can see that capacitive keyboards have similar “mounting constraints” to magnetic ones, in that they require a structure that keeps the distance between the switch plate and PCB constant.
It’s helpful to think of it as “harder to move the mount freely compared to a typical mechanical keyboard.”
REALFORCE and HHKB Fix the Switch Support Surface Differently
As we’ve seen, capacitive keyboards require a structure that minimizes changes in the distance between the switch support surface and the PCB.
The most iconic capacitive keyboards in Japan are the “REALFORCE” and “HHKB Professional.”
While both use the same capacitive method, they differ in how they support the switches.
REALFORCE: Independent switch housings supported by a metal plate
HHKB Professional: Switch housings integrated with the resin upper case
However, this isn’t a difference of “fixed vs. not fixed.”
They use different methods, but both fix the distance between the switch support surface and the PCB.
REALFORCE Fixes with a Metal Plate
In the HHKB development history published by PFU, the REALFORCE is described as having a structure where each individual key switch is independent and attached to a metal plate.
“REALFORCE basically has a structure where each individual key switch is independent and attached to a metal plate.”
While the metal plate handles switch support and positioning in the REALFORCE, the resin upper case itself does that in the HHKB Professional.
Since there’s no metal plate, it looks like a very different structure from the REALFORCE.
However, the HHKB Professional also doesn’t have a structure where the switch support surface sinks freely relative to the PCB.
The distance between the switch housings integrated with the upper case and the PCB placed underneath is fixed.
So the difference between the two isn’t “whether to fix the switch support surface,” but rather “what material is used to fix it.”
Different Structures, Same Goal: Fixing the Switch Surface and PCB
Summarizing the structures of REALFORCE and HHKB Professional:
Product
Switch Support Method
Positional Relationship with PCB
REALFORCE
Independent housings supported by a metal plate
Fixed
HHKB Professional
Housings integrated with the resin upper case
Fixed
The difference is that REALFORCE uses a metal plate while HHKB Professional uses a resin upper case.
However, they share the basic concept of layering the rubber dome, conical spring, and PCB underneath to fix the distance between the switch support surface and the PCB.
It’s more accurate to think of REALFORCE and HHKB Professional not as having “different mounting methods,” but as “satisfying the same structural requirements using different support materials and fixing methods.”
This commonality highlights that capacitive keyboards, like magnetic ones, need to stabilize the positional relationship between the switch-side input mechanism and the PCB-side detection unit.
The Relationship Between Fixed Structures and Typing Feel
The “hardness” of the typing feel here refers to the sensation transmitted to the fingertips when bottoming out a key.
When the switch plate is rigidly fixed, there is almost no “flex” to dissipate the impact of bottoming out.
Since the reaction force when the key hits the bottom is clearly returned to the fingertip, it tends to result in a hard bottoming-out feel.
In contrast, in a typical gasket mount, the input unit (including the plate and PCB) sinks slightly due to the deformation of the gasket material.
The impact of bottoming out is dispersed by the gasket’s deformation and the plate’s flex, resulting in a soft, cushioned sensation at the fingertips.
Of course, the final typing feel isn’t determined by the mounting method alone.
Plate material and thickness, the PCB, dampening materials, switches, keycaps, and the case all play a role.
However, whether there is room for the entire structure to sink during bottoming out is a major factor in the perceived hardness at the fingertips.
In capacitive keyboards, the distance between the switch support surface and the PCB must be stable.
This makes it difficult to adopt a structure where the switch plate sinks significantly relative to the PCB to dissipate the impact of bottoming out, as seen in typical mechanical keyboards.
This seems to be one of the structural constraints arising from the input method, much like with magnetic keyboards.
HHKB Might Soften Bottoming-Out Hardness with its Integrated Resin Structure
REALFORCE supports its switches with a highly rigid metal plate.
While HHKB Professional also has a fixed structure, it uses resin for the material that supports the switches.
In PFU’s development history, the typing feel of the metal-plated REALFORCE is described as “solid,” while the integrated resin HHKB Professional is called “soft” and “supple.”
The HHKB Professional is not a gasket mount.
Still, by using the resin upper case as the support surface instead of a metal plate, it might be creating a more supple bottoming-out feel than a metal plate while maintaining the stability required for a fixed structure.
In other words, we could hypothesize that the HHKB Professional “softens the hardness inherent in fixed structures by using resin as the support material while keeping the distance between the switch surface and PCB fixed.”
This might be one reason why REALFORCE and HHKB Professional don’t feel the same, even though they use the same capacitive method.
Capacitive Keyboards Aren’t Incapable of Using Gasket Mounts
In a typical gasket mount, the input unit (including the plate and PCB) is supported by gasket materials.
The deformation of the gaskets allows the input unit to sink slightly, dispersing the impact of bottoming out.
So, is it impossible for capacitive keyboards—which need a fixed distance between the switch surface and PCB—to use a gasket mount?
It’s not theoretically impossible.
If the switch support surface, rubber dome, conical spring, and PCB are fixed as a single unit, and that entire unit is given cushioning while maintaining their relative positions, it could mitigate the impact of bottoming out.
A good reference here is the “Lofree Hyzen,” a hybrid keyboard that supports both magnetic and mechanical switches.
The Hyzen is specified as having a “PCB Gasket + FR4 Fiberglass Plate” according to Greenkeys’ product checks, and the use of a gasket mount is clearly stated on the official Lofree page.
In a typical plate gasket, the gasket material is placed on the switch plate side to elastically support the plate from the case.
In contrast, a PCB gasket supports the PCB side with gasket material.
By giving the PCB side cushioning, the Hyzen likely softens the bottoming-out impact without moving the switch plate independently from the PCB.
This can be seen as a clever way to add gasket-like softness while maintaining the positional relationship between the internal switch magnet and the TMR sensor required for magnetic switches.
In short, it’s not that magnetic or capacitive keyboards can’t use gasket mounts.
It’s that they need to provide cushioning to the input unit in a way that doesn’t change the distance between the switch support surface and the PCB.
However, capacitive keyboards require the switch support surface, rubber dome, conical spring, and PCB to be held in a specific state.
The same PCB gasket structure used in the Hyzen might not be directly applicable to the capacitive method.
Still, one could imagine a method where the PCB side or the entire input unit is supported by gaskets while maintaining the positional relationship of the entire input mechanism.
Therefore, rather than saying capacitive keyboards *can’t* use gasket mounts, it’s more accurate to say that it’s harder to move the mount structure as freely as in a typical mechanical keyboard.
Fixing is necessary.
However, there is still room to add cushioning to the entire fixed structure.
Looking at the Hyzen’s PCB gasket structure, it seems possible that capacitive products with a different bottoming-out feel than before might emerge.
Summary | The Deep Connection Between Input Methods and Typing Feel
That concludes this column on the potential constraints on mounting methods when using traditional capacitive non-contact switches.
Recently, modular EC switches have also appeared, which I’m watching with interest.
I get the impression that the typing feel of capacitive keyboards is particularly favored in Japan.
Personally, I really liked the feel of the HHKB 30g model.
The rubbery feel as it sinks and the bottoming-out sensation—which is a bit firm yet somehow elastic precisely because of the integrated resin structure—feels uniquely HHKB.
On the other hand, that’s not the “be-all and end-all.” While it comes down to preference, there are many other keyboards with typing feels that I find excellent.
Ultimately, you won’t know your own preference until you touch and experience various keyboards for yourself.
Don’t just settle for your current keyboard; try out different ones. Experiencing that depth will help you appreciate the charm of keyboards even more.
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