The Kailh Nexus Switch is the industry’s first mass-produced switch to integrate a mechanical metal contact leaf with Hall-effect magnetic sensing within a single unit. The core engineering challenge lay in preventing mutual interference between the magnet’s magnetic field and the physical structure of the contact leaf when they coexist within the same switch stem space. Kailh’s solution was ”physical isolation combined with functional decoupling”: the leaf and the magnet are positioned in separate zones within the stem—the leaf handles tactile feel and mechanical actuation, while the magnet handles Hall-effect sensing, ensuring neither interferes with the other. However, this design comes with a structural trade-off: currently, the Nexus Switch can only enable dual-mode switching on specialized PCBs (such as the Lofree HYZEN); installing it in a standard mechanical keyboard or a dedicated magnetic-switch keyboard prevents it from fully utilizing the potential of its dual ”hearts.”
I. Why a ”Two-in-One” Design?
For years, mechanical switches and magnetic switches have occupied parallel tracks. Mechanical switches rely on metal leaf contact for actuation, offering tactile bumps and the characteristic sound of the leaf, yet they suffer from fixed actuation points and lifespans limited by contact point wear. Magnetic switches utilize Hall sensors to detect magnetic field changes, supporting features like Rapid Trigger, DKS, SOCD, 0.01mm-level actuation precision, and superior durability, but they offer a linear feel and lack physical tactile feedback.
The weaknesses of one are precisely the strengths of the other. Kailh chose to combine these two paths into a single switch: the metal leaf preserves the typing texture and bottom-out feedback of a mechanical switch, while the magnet and Hall sensor provide the adjustable travel and esports-oriented features of a magnetic switch.
II. The Nature of the Interference Problem
Placing both a magnet and a contact leaf inside the same switch stem introduces several risks of physical interference.
Magnetic circuit interference is the primary concern. The contact leaf is made of a copper alloy; while copper itself is non-magnetic, the leaf deforms during actuation. If the leaf’s position or movement trajectory brings it too close to the magnet, it could theoretically cause minor disturbances in the magnetic field distribution, thereby affecting the Hall sensor’s accuracy in reading the travel position.
Competition for internal space is the second issue. In traditional mechanical switches, the space within the stem accommodates only the metal contact leaf and the spring, whereas in magnetic switches, it houses only the magnet and the spring. The Nexus Switch, however, requires housing both systems within the same stem while maintaining the standard MX switch dimensions and a total travel distance of 3.5mm.
Acoustic interference presents a third challenge. The presence of the contact leaf alters the internal acoustic chamber; when the magnet and the leaf coexist, the sound profile and resonance characteristics shift.
III. Kailh’s Solution: Physical Isolation and Functional Decoupling
During the development of the Nexus Switch, Kailh established two clear engineering objectives: ensuring no interference between the magnet’s magnetic field and the contact leaf, and maintaining dimensional compatibility despite integrating dual-triggering capabilities.
An analysis of the Nexus Switch’s structure reveals a solution characterized by ”separation and decoupling.” The stem is made of POM and contains a Neodymium-Iron-Boron (NdFeB) permanent magnet to generate the field required for the Hall effect sensor. Meanwhile, the contact leaf assembly (comprising a moving copper alloy leaf and a stationary leaf) is housed in a separate zone on the side of the stem, handling mechanical actuation and bottom-out feedback. These two systems are physically separated; the contact leaf’s movement path avoids the magnet’s effective field zone, and the magnet’s field does not extend to the contact points of the leaf.
Crucially, the functions are decoupled. The contact leaf is responsible solely for ”tactile feel” and ”mechanical conduction,” while the magnet handles ”magnetic sensing actuation.” In magnetic switch mode, the contact leaf plays no role in signal generation; in mechanical switch mode, the magnet does not participate in trigger detection. Each system operates independently, eliminating logical conflicts—such as the need for arbitration between simultaneous contact-based and magnetic signals.
IV. Operational Logic of the Dual-Mode System
It is important to clarify a common misconception: the ”dual-mode” capability does not mean the switch itself automatically toggles between modes. Instead, the operating path is determined by the PCB on which the switch is installed. When mounted on a standard mechanical keyboard, it functions as a mechanical switch (using contact leaf conduction); when mounted on a standard magnetic keyboard, it theoretically utilizes the Hall effect path (though pin compatibility issues may arise). What truly enables the simultaneous availability of both systems is the dedicated PCB found in the Lofree HYZEN. The HYZEN board supports both mechanical and magnetic switch architectures, allowing for board-wide mode switching via a physical toggle on the keyboard. When switched to the mechanical mode, the system relies on metal leaf contact, with a fixed actuation point of 1.3mm; when switched to the magnetic mode, it utilizes Hall-effect sensing, allowing the actuation point to be customized between 0.01mm and 3.5mm via software, while also supporting features like Rapid Trigger and DKS.
V. Structural Trade-offs
The ”physical isolation + functional decoupling” approach of the Nexus Switch solves interference issues but entails several unavoidable trade-offs.
PCB compatibility is the most immediate issue. Magnetic switch PCBs lack the pinholes required for mechanical switch leaf contacts; installing the Nexus Switch onto a magnetic switch keyboard necessitates trimming the leaf contact pins, which permanently disables the mechanical mode. Conversely, when installed on a standard mechanical keyboard, the lack of corresponding sensing circuitry for the magnet and Hall sensor renders the magnetic switch functions inoperable. In essence, the Nexus Switch is currently a ”specialized switch” compatible only with the HYZEN keyboard.
Old issues associated with mechanical modes have resurfaced. Metal contacts bring about problems such as contact bounce, the need for debouncing strategies, and long-term oxidation—issues that have plagued mechanical switches for decades. While the era of pure magnetic switches had shed this ”baggage,” the Nexus Switch reintroduced it to achieve a specific typing feel. Some early HYZEN users reported double-clicking issues in mechanical mode, a problem rooted in the physical contact characteristics of the metal leaf.
Challenges in acoustic tuning. The coexistence of the metal leaf and the magnet encroaches upon the internal acoustic space of the switch. Some reviews describe the Nexus Switch’s sound as a ”muffled, Hi-Fi ’mahjong tile’ sound”—a positive attribute derived from the metal leaf—while others criticize the sound quality, indicating inconsistencies in acoustics across different production batches or keyboard structures.
VI. Specifications
The Nexus Switch is currently available in only one specification:
Operating force: 40 ± 10 gf
Actuation travel: 1.3 ± 0.4 mm (adjustable in magnetic switch mode; fixed in mechanical switch mode)
Total travel: 3.5 ± 0.2 mm
Initial magnetic flux: 90 ± 15 Gs
Bottom-out magnetic flux: 480 ± 40 Gs
Mechanical lifespan: 80 million cycles; supports hot-swapping (not solderable); operating temperature: -10°C to +70°C.
