Keyboard Builders' Digest / Projects
Umbra
A unibody ergonomic keyboard with self-encasing PCB: Umbra by skarrmann.
Published April 6, 2023
Umbra is a 24-key monoblock angled keyboard by Steve Karrmann.
Like the author's split Janus, Umbra uses multiple copies of the same PCB as both the logical PCB and the bottom plate. However, this design is intended for unibody keyboards.
Specs
- 24 keys, unibody layout
- low-profile Choc switches, soldered (not hotswap)
- Pi Pico (or RP2040-Plus)
- direct pins, no diodes
- self-encasing PCB
Here is a short video showing the board from all angles:
Umbra - full keyboard view
Self-encasing PCB
The keyswitches are rotated 180 degrees on opposite sides of the board, so cutouts for the through-hole solder pads align. This allows the PCB to work as a bottom plate, keeping the bottom of the board flush with a thin profile.
While we've seen similar approaches – bottom plates with cutouts to protect switch pins and components while ensuring the lowest possible profile –, in contrast to the separate PCB of the Horizon, chocV/slabV or lately the ChonkV, the Umbra uses the very same PCB for this task.
As someone who doesn't have a 3D printer and always has leftover custom PCBs given the minimum order quantity of 5, this self-encasing PCB design is a resource-saving technique – skarrmann.
Steve thinks there is more potential for this self-encasing PCB design concept for unibody keyboards. Keyboards with larger key counts that require diodes could use this design too, as long as the diodes are SMD top-mounted, or have cutouts for the diodes on the opposite half of the board.
Resources
The Umbra keyboard is open source. The project readme has more details about how the self-encasing PCB design works:
Published on Thu 6th Apr 2023. Featured in KBD #119 (source).