Membrane Switch Design Factors

FACTORS GOVERNING ACTUATION FORCE

  1. Thickness of individual layers
  2. Size of switch opening in spacer
  3. Type of actuator
  4. Embossing

MOUNTING OPTIONS

RIGID BASE
  1. Holes through all layers
  2. Studs or standoffs
    1. 4:40, 6:32, 8:32, 10:32
    2. Metric M1. M2 and M3
  3. Rear mounting adhesive or insulator
  4. Mechanically restrained by bezel

FILM BASE

  1. Rear adhesive
  2. Holes through all layers

ESD SHIELD TO GROUND

METHOD
  1. Silver, carbon, or carbon/silver blend conductive inks screened in a crosshatch pattern on top of the membrane
  2. Solid aluminum shield

METHOD OF INTERCONNECTING TO ESD SHIELD

  1. Trace brought out on top of polyester tail
  2. Tab(s) brought out on perimeter
  3. Grounding stud for rigid base

RFI/EMI SHIELDING TO GROUND

  1. Transparent conductive material
  2. Aluminum foil
  3. Conductive inks screened on entire top surface of membrane

GRAPHICS

COLORS
  1. As available from Pantone Matching System
  2. Custom color samples (minimum 1" sq.) can be matched by Spectro Photometer.

CUSTOMER SUPPLIED ARTWORK

  1. Required for custom logos and symbols
  2. Artwork will be used to produce production phototools
  3. One times size
  4. Polyester silver film .004" or .007" thick
  5. Free of scratches, pinholes, folds. etc.
  6. Stroke width of letters .015" min.
  7. Typical graphic line width 030" min.

DISPLAY FILTERS

TYPES
  1. Clear/tinted
  2. Translucent
  3. Polycarbonate (option of hardcoat), drop in filter for film or rigid. The filter may be trapped within switch layers or adhesively attached. Thickness varies dependent on application
  4. Dead fronting allows the indicators, icons and other graphics to be not noticeable until they are illuminated.

FEEDBACK

VISUAL
  1. Variety of LED's in SMT configuration or other.
  2. T1,T1 3/4 LED's
  3. Seven segment displays
  4. Bar graph displays
  5. Liquid crystal display (LCD), vacuum florescent display(V.F.D.)
  6. Colored filters usually enhance light visibility

Note: LED location should be designed to seat outside of active switch area.

AUDIO

  1. PC board assembly can be furnished with audible device which can interface with film base switch giving an indication of switch closure.
  2. Audible device and associated components can be mounted to a rigid printed circuit base switch

TACTILE: METAL OR FORMED POLYDOMESSHAPE ACTUATION

  1. Available for film and rigid base designs
  2. May be used as a passive or active component of the switching circuit
  3. Dome enclosure layer replaces overlay adhesive
  4. Dome enclosure layer typically .007" -.011" thick

DOMES

  1. Stainless steel: Domes are available in various sizes and shapes. Tolerance on actuation force is 2 oz./56.8 grams. In normal conditions life expectancy should exceed 3,000,000 actuations, abnormal methods of actuation and/or excessive force will reduce life expectancy.
    1. Storage and operating temperatures:
      -400 C to +900 C
    2. Electrical specifications: Refer to rigid or film base product specifications.

    STAINLESS STEEL DOME SPECIFICATIONS

    SIZE (in/mm)

    SHAPE

    ACTUATION FORCE IN OUNCES/GRAMS (DOME ONLY)

    DOME LIFE EXPECTANCY

    .500/12.7

    Round

    12/340.8, 14/397.8

    3,000,000

    .472/12

    Round

    10/284, 12/340.8, 17/482.8, 19/539.6

    3,000,000

    .433/11

    Round

    14/397.8

    3,000,000

    .394/10

    Round

    10/284, 12/340.8, 14/397.8

    3,000,000

    .354/9

    Round

    10/284, 12/340.8, 14/397.8

    3,000,000

    .50 x 1.0, 12.7 x 25.4

    Rectangular

    12/340.8

    3,000,000


  2. Polydomes: Thermally formed into polyester membrane layer, available in round configuration only. Tolerance on actuation force is +/- 2 oz./56.8 grams. In normal conditions life expectancy is greater than 1,000,000 actuations, abnormal methods of actuation and/or excessive force will reduce life expectancy.
    • Storage and operating temperatures: -400 C to +500 C
    • Electrical specifications: Refer to rigid or film base product specifications.

    POLYDOME SPECIFICATIONS

    SIZE (in/mm)

    ACTUATION FORCE IN OUNCES/GRAMS (DOME ONLY)

    DOME LIFE EXPECTANCY

    .375/9.53

    16/454.4

    1,000,000

    .344/8.74

    16/454.4

    1,000,000

    .340/8.64

    17/482.8

    1,000,000

    .340/8.64

    12/340.8

    1,000,000

    281/7.14

    12/340.8

    1,000,000