|Manufacturer||Hewlett-Packard W.H. Brady Co|
|Keyswitches||Capacitive Rubber dome over membrane|
|Years of production||1987-1989|
The HP C1405A is a model of Capacitive rubber dome over membrane keyboard. HP registered this keyboard with the FCC in 09/1987. Manufacturer stamps on known keyboards range from 1988 to 1989. The Hewlett-Packard logo is stamped on the controller PCB and Rubber dome sheet. The capacitive membrane was patented by W.H. Brady Co in 1988 and therefore not made by HP. 
The keyboard features n-key rollover a thick metal backplate and an IBM Model M compatible SDL cable. The top and bottom case are held together with 11 screws. The backplate is held to the top case via two plastic clips. The top row of barrels are clipped into the barrel plate, while the rest are stamped into place and cannot be removed. The keycaps feature red Dye sublimation.
Controller PCB with IBM Model M compatible SDL connector
- ↑ https://patents.google.com/patent/US4562315A US Patent 4562315 "Capacitance membrane switch"