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Fujitsu FKB2500 Series


Fujitsu FKB2500 Series is a third-generation leaf spring standard and custom mechanical keyboard series. It was available in both “non-snap” linear and “snap” clicky versions. It is designed to be DIN-compliant. Fujitsu reported that these keyboards use FES-301E switches, where “E” denotes “ergonomic” (DIN-compliant).

The characteristics are curious. The bounce time at 10 ms is twice the typical bounce time of mechanical switches, but the 50 million cycle lifetime is substantially in excess of most mechanical switches of the time. The target operating force is approximately 50 cN. The tactile drop is depicted as around 5 cN.


The specifications below cover the individual switch units. The data below is taken from the datasheet.

Total travel 3.8±0.5 mm
Operating force 49±24 cN
Lifetime 50 million times
Contact resistance 1 Ω or less at 6 V DC, 10 mA
Bounce time 10 ms or less



The FKB2500 Series datasheet was obtained from the Fujitsu Components Limited (FCL) website; Fujitsu have since removed this material due to product cancellation.