Clare foam and foil

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Clare foam and foil
Manufacturer Clare, General Instrument
Sense method Capacitive

Clare foam and foil is a type of foam and foil switch manufactured by Clare and seemingly also the parent company General Instrument. The series name of S-890 is tentatively identified with this series, but not confirmed in any way.[1]

The earliest known example is from 1981, branded "CP CLARE" and marked "ASM MEXICO". This keyboard pre-dates the various foam and foil patents filed by General Instrument in 1982. A 1982 Cray keyboard has been found with a single "CP CLARE"-branded switch alongside unbranded switches, giving a small indication of the change in branding.[2] A 1982 keyboard has been found with the PCB branded "General Instrument".[1]

Like with various other foam and foil switch types from the likes of Key Tronic and Cherry, these switches use discrete modules to hold the slider and springs, mounted into a plate.


The following patents may be relevant:

Applicant Patent Filed Published Notes
General Instrument Corporation EP 0072784 Keyswitch design 1982-08-10 1983-02-23 Single-sided PCB with through-hole-soldered capacitor pads
General Instrument Corporation US 4450332 Keyswitch design 1982-08-25 1984-05-22 This may be the switch series in question
General Instrument Corporation US 4454562 Keyswitch with telescoping plunger 1982-09-15 1984-06-12
General Instrument Corporation US 4453198 Linear feel keyswitch with hysteresis 1982-09-15 1984-06-05


  • Unidentified keyboard from 1981[3]
  • Cray Research keyboard from 1982 (GI PCB branded as Ampex; GI controller)[2]
  • Unidentified keyboard from 1982, marked "GENERAL INSTRUMENT | Keyboard Division" and model "S-890 Series"[1]