Key Tronic foam and foil

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Key Tronic foam and foil

Manufacturer	Key Tronic
Switch type	Linear, tactile
Sense method	Capacitive
Keycap mount	Key Tronic

Key Tronic foam and foil is a type of foam and foil switch manufactured by Key Tronic.

Description

Key Tronic foam and foil switches were apparently tactile from the outset, using buckling rubber sleeves. In 1981, Key Tronic introduced a linear variant by popular request; this was referred to as the Butterfly™ switch.<ref name="geekhack-Butterfly" /> The headline "floats like a butterfly" suggests that the moniker derives from the smooth feel of the switch, while it is also suggested that the name refers to the design of the capacitor pads on the PCB, potentially without regard to the force curve.<ref name="DT-Butterfly" />

Being capacitive, Key Tronic keyboards using foam and foil switches are N-key rollover.<ref name="geekhack-Butterfly" /> Key Tronic referred to their foam and foil switches in advertisements as "solid state"; Cherry also referred to their foam and foil switch as solid state, even though both have moving parts.

Some Key Tronic switches are branded on the top, but most are unbranded.

Variants

Linear

Marketed as the "Butterfly™ switch"<ref name="geekhack-Butterfly" />; external return spring placed under the keycap

Tactile

Uses a buckling rubber sleeve

Keyboards

• Apple Lisa (linear)<ref name="OneTrueKeyboard-Lisa" />
• Compaq Deskpro 286 AT keyboard (tactile)<ref name="geekhack-Deskpro" />
• Compaq Enhanced Keyboard (unbranded; tactile)
• Key Tronic Model F clone series (linear and tactile)
• Wang 723T/KBD-UST (unbranded; tactile)
• Franklin Ace 1000/1100/1200 (linear)
• SOL-20 (linear)
• Tandberg Data TDV 2115L and TDV 2115C (presumed linear)<ref>Deskthority — Is this board mechanical?</ref>
• Unisys F420800 (Unbranded; Linear)

Gallery

• 
  Presumed to be linear foam and foil switches; unbranded
• 
  Branded linear switch from a 1983 keyboard
• 
  Unbranded tactile switches from a Key Tronic E03091007 keyboard
• 
  Switch housings, rubber sleeves and sliders with foam discs.

• 
  Tall stem switch from Jan. 1983 board
• 
  Tall stem switch from Jan. 1983 board
• 
  Tall stem switch from Jan. 1983 board
• 
  Short stem switch from June 1983 board
• 
  Short stem switch from June 1983 board
• 
  Short stem switch from June 1983 board (spring glued in place)

References

<references> <ref name="geekhack-Butterfly">Geekhack — Old Keytronic advert sounds new Dated 2014-04-15. Retrieved 2015-07-28.</ref> <ref name="geekhack-Deskpro">Geekhack — Compaq Deskpro 286 AT Keyboard Dated 2013-12-10. Retrieved 2015-07-28.</ref> <ref name="OneTrueKeyboard-Lisa">OneTrueKeyboard — Keyboard on the Apple Lisa Dated 2006-05-16. Retrieved 2015-07-28.</ref> <ref name="DT-Butterfly">Deskthority — Potential new name for the linear Key Tronic F&F switch</ref> </references>