The use of magnetic contacts for a detachable numpad is, in essence, an electromechanical coupling solution that combines “magnetic-guided locking” with “Pogo pin (spring-loaded pin) electrical connectivity.” This design liberates the keyboard from the constraints of cables, enabling a seamless, “snap-on” user experience that requires no visual alignment. From the ROG Claymore II—a gaming-focused keyboard with a modular, split-architecture design—to the Epomaker RT98, which caters to retro-aesthetic setups and left-handed users, this technology is rapidly becoming a standard feature in high-end modular mechanical keyboards.
I. Magnetic Attraction for Alignment, Contacts for Communication
The core logic of this design lies in decoupling the tasks of “physical fixation” and “electrical connection.”
The magnetic system (utilizing magnets and magnetic-responsive metal) serves the functions of “guidance” and “retention.” Magnets with opposing polarities are concealed along the mating surfaces of the numpad module and the main keyboard. As the user brings the numpad toward the main keyboard, the magnetic force automatically corrects minor positional deviations, “pulling” the module into its precise, intended location. Once attached, the magnetic force provides sufficient holding power to ensure the module remains securely in place during typing or when the keyboard is moved.
The contact system (typically employing Pogo pins) handles “signal transmission and power supply.” On the mating interface, the main keyboard features flat metal contact pads, while the numpad module is equipped with retractable, spring-loaded pins. As the magnets pull the components together, the pins are compressed, creating a stable, low-resistance connection against the contact pads. Through these points, the main keyboard’s microcontroller (MCU) supplies power to the numpad and receives key-press data scanned from the numpad’s internal matrix.
II. How the Microcontroller Detects the “Numpad Connection”
Once the contacts are engaged, the main microcontroller must recognize that the peripheral has been connected before it can begin polling for key-press data. There are two common methods: hardware circuit detection and Hall-effect-assisted sensing.
A pin on the main controller continuously monitors the circuit loop. When the contacts on the numeric keypad module engage with the main keyboard, the voltage level at the detection pin is pulled low—or a closed loop is formed—signaling to the main controller that the numeric keypad has been connected, which then triggers data polling. Some high-end solutions (such as those found in custom keyboard kits integrated with smart modules) also employ Hall-effect sensors at the connection point; these detect the proximity of a magnet to wake up the system, after which data is transmitted via the physical contacts.
III. Typical Product Applications: From Modular Gaming Keyboards to Desktop Setups
This technology has already been implemented in several flagship products, manifesting in various form factors.
The ROG Claymore II is a prime example of a modular gaming keyboard architecture. Its numeric keypad module attaches to the side of the main keyboard via a rail system, establishing a connection through physical metal contacts, while magnetic covers help secure it in place. This design allows users to position the numeric keypad on either the left or right side of the main keyboard—or remove it entirely—depending on their available desk space and personal gaming preferences.
The Epomaker RT98 takes the concept of magnetic contacts a step further. Its numeric keypad module can be swapped between the left and right sides, and it also features a 1.14-inch “Mini TV” screen that connects via magnetic Pogo pins. This screen can be detached at any time; when connected, it uses the contacts to display system status or custom GIFs. The RT98 demonstrates that magnetic contacts can handle not only keyboard matrix data but also the data throughput required for a small display screen.
Furthermore, within the custom keyboard community, modular kits from brands like Keychron—as well as certain magnetic-switch keyboards designed for versatile use (such as the Lofree HYZEN series, which supports hot-swappable modules)—extensively utilize similar contact-based connection logic for internal wiring or external expansion.
IV. Engineering Constraints: Short-Circuit Prevention and Contact Lifespan
To ensure the reliability of this approach, engineers must overcome two primary challenges. Safety risks associated with hot-swapping. Users might detach the numeric keypad while the keyboard is powered on. In such a scenario, if the exposed pogo pins or metal contact pads are bridged by a foreign metallic object—such as a key or a bracelet—it could trigger a short circuit. Consequently, well-engineered products feature a contact layout that maximizes the spacing between power and signal contacts, or incorporate mechanical “poka-yoke” (error-proofing) slots. These designs ensure that the main controller can instantly cut off power to the circuit the moment the module is detached.
Contact lifespan and contact resistance. The spring inside a pogo pin is a component subject to mechanical wear. Frequent attachment and detachment can lead to spring fatigue and reduced contact pressure, which in turn increases contact resistance and compromises signal integrity. Therefore, the thickness of the gold plating on the pins and the material used for the springs (such as music wire) are critical factors in the long-term durability of a modular keyboard. Furthermore, the contact pads on the main keyboard unit typically undergo an immersion gold (ENIG) plating process to withstand the wear caused by frequent, high-frequency friction.
