Membrane Technical Guide

Basic Structure

Membrane Structure
Membrane Design Guide Membrane Design Guide

Specifications

  

Electrical Characteristics

Mechanical Characteristics

Environmental Properties

Item

Contact resistance
Insulation resistance
Withstand voltage
Contact bounce
Operation load
Stroke
Operation life
Operating temperature and humidity
Storage temperature

Typical Characteristic value

100 Ohm or less
100M Ohm or more at 100V DC
125V AC for 1 minute
15m sec or less
50~300g
more than 0.1mm
Over 1,000,000 cycles
-10ºC+50ºC at 90% RH or Less
-25ºC+70ºC

Life Test Data

  

Parameters
Heat resistance
Low temperature resistance
Moisture resistance

Temperature cycle

Sulfide resistance
Vibration resistance
Impact resistance

 Membrane Design

Membrane Switches & Flex-Circuits

Both Flex Circuits and Membrane Switches share many similarities. Flex circuits can function as membrane switches, including dome arrays and circuitry. The major difference in the two is the manufacturing process.

Flex circuits typically start with a thin film of Polyimide (PI) or Polyester (PET). A layer of copper is applied to the surface of the sheet, and then the circuit is photo etched to provide the final circuit pattern. This is a ‘subtractive’ process. An overcoat is applied for protection.

Membrane switches (as we are able to manufacture them) are an additive process, where a conductive silver layer is silk screened to produce the circuit pattern. Although the quality is equivalent to flex circuits, the detail of features of membrane switches is not as fine as that of flex circuits where tiny through holes and trace widths are possible. Many components can additionally be added to the circuit, although the range is not as great as what’s possible with circuit boards or flex circuits.

Shown on the left is a flex circuit with a rigid substrate. Notice the fine trace widths and small through-hole vias. Shown on the right is a membrane switch displaying the silk-screened button pattern and PC film graphic overlay.

Membrane Switches & Flex Circuits

Membrane Switch Design Options

Membrane Switch Design Guides
Generally, the thickness of these types of membrane switches is about 1.8mm (LED H=1.1mm) or 1.3mm (LED H=0.5mm).
The thickness can be increased up to 2-3mm by simply increasing the thickness of either double-sided adhesive layer.

Membrane Switch Design Options

General Considerations for Switch Specifications

Environmental

  • What temperature and humidity range will this product experience?
  • What type of contaminants or chemicals will come into contact with this product?
  • Will this product be subjected to moisture and/or UV exposure?

Electrical

  • How many contact points will there be?
  • What type pin out or matrix will be used? (common bus, X-Y matrix)
  • What closed loop resistance will be acceptable?
  • Will electrostatic or EMI shielding be necessary?

Mechanical

  • Will tactile response be required?
  • To what material will the switch be laminated?
  • What number of actuations will this product receive?
  • Will actuation force be a factor?

Appearance

  • Will edges be exposed, recessed, or covered with a bezel?
  • Will embossing be required?
  • Will there be different parts to the same product? (sets)
  • How many colors will be needed?
  • Will graphic effects be used such as halftones or shadowing?

Physical

Environmental
General Considerations for Switch Specifications Environmental Considerations

Electrical

  
Electrical Considerations  

Note – These specifications are typical. Your application will need to be evaluated and specifically designed to fit your use.