The ikbc Light Box 87 features a Gasket-mount structure specifically designed for magnetic switches. By combining an aluminum alloy positioning plate with seven layers of tuning material, it addresses common pain points in magnetic-switch keyboards: harsh bottom-out feel and sharp, high-pitched impact sounds caused by the magnets. Rather than simply stuffing the case, the acoustic design employs various materials—foams, films, and pads—to filter specific frequency bands and dampen vibrations, creating a multi-stage physical barrier that attenuates sound from the moment of bottom-out all the way to chassis resonance.
The acoustic roles of these seven layers, from the bottom case up to the positioning plate, are as follows:
1. Bottom Case Transparent Film
Positioned at the very bottom, this film lines the interior of the bottom case. It seals the bottom cavity, using its tension to reflect sound waves and prevent them from penetrating the case, which would otherwise result in a dull, hollow „cavity sound.“
2. Bottom Case Pad
Located above the transparent film, this layer serves as the primary bottom-cushioning component. Its main function is to absorb and suppress residual low-frequency resonance that passes through the upper layers. It also fills the excess space between the bottom case and the internal assembly, ensuring that the bottom-out sound is solid, crisp, and free of lingering, muddy echoes.
3. PCB-Backing Foam
Placed directly against the back of the printed circuit board (PCB). Since the Hall-effect sensors and surface-mount components of magnetic switches are typically located on the back of the PCB, this foam layer serves a dual purpose: it absorbs unwanted noise beneath the PCB while accommodating the uneven surface created by these components. This prevents rigid pressure from deforming the PCB, thereby maintaining the structural integrity of the magnetic switches‘ mounting plane.
4. Switch-Underlay (IXPE/Foam Pad)
Situated on the top side of the PCB, directly beneath the switches, this is the most critical layer for controlling the „bottom-out timbre.“ When a magnetic switch bottoms out, the magnet at its base can strike the internal structure—either directly or indirectly—producing a sharp, high-pitched impact sound. The switch pad serves to physically cushion and dampen high-frequency impacts, transforming the characteristically sharp „click“ into a deeper, more focused thud.
5. Transparent Film (Dual-Layer Structure)
Two layers of transparent film are placed over the switch pad. In acoustic tuning, thin-film materials are often used to isolate specific frequency ranges and reflect sound waves via their inherent rigidity. This dual-layer design further prevents high-frequency noise from dispersing upward, while simultaneously helping to concentrate the sound generated below.
6. Interlayer Foam
Positioned between the mounting plate and the PCB, this layer fills the gaps around the switches and beneath the plate. It absorbs noise that would otherwise radiate outward during key presses and minimizes direct contact between the plate and the PCB, thereby preventing harsh, rigid resonance.
7. Aluminum Alloy Mounting Plate (Structural Foundation)
While not an „acoustic-dampening“ material, the aluminum alloy mounting plate—located at the very top—acts as the „skeleton“ for the entire acoustic and tactile system. Its high rigidity ensures that the magnetic switches remain stable and resistant to deformation during use, maintaining a precise, consistent spatial relationship between the magnets and Hall-effect sensors for accurate actuation. Furthermore, it transmits the vibrations from key presses—with a crisp, distinct quality—down into the underlying dampening layers; combined with the gasket-mounted structure, this creates a soft, responsive, and „springy“ bottom-out feel.
