Membrane Keyboard Technical Specification:

Electrical and Mechanical Characteristics:

Graphic Overlay Characteristics

** Please note that full chemical resistance data is available and will be sent on request.

Tests on specific chemicals can be conducted at customer request.

  Keyboard Design: 

Basic Design Rules: Does your application require tactile or touch switches?  About 85% of our current production have tactile feel switches. However, both types have advantages and disadvantages as follows:

Touch Switches: Can be any size from very, very, small (though a finger is roughly a 15mm circle) to very, very, very  big (the largest we have made was 4000mm square for a dance floor). Can have a wide range of closure and release pressures from less than 10g to more than 15kg.  A good example was a switch designed to close when a full beer bottle was placed on it and open if the bottle was empty.  This was used to monitor bar staff!  The lifetime of a touch panel is governed by the 'abrasiveness' of the human finger - lifetimes in excess of 10 years can be easily achieved.  A major disadvantage is the lack of user feedback.  Control panels often beep on switch use, but this is not as satisfying as a click under the finger. Touch switches can also be activated by simply cleaning the panel.  

Tactile Switches: All these have a stainless steel dome located under the switch graphic.  These are generally circular although some rectangular domes are available.  The size is limited to the size of the dome - minimum 6mm, maximum 20mm, but domes can be placed in a row to produce long, thin switches such as the Space Bar on a computer keyboard. Switch pressures are limited unless the volumes warrant a custom made dome.  We have a range of pressures from 90g to 500g. Lifetime is shorter than a touch switch but nevertheless all our smaller domes will tolerate a minimum of 5 million, and the larger ones 1 million, closures. Tactile panel switches are difficult to actuate during cleaning.

Physical Considerations: Switches of either type should be separated by at least 2mm.  Switches should be at least 5mm and preferably 10mm from the keyboard edge and a similar distance from LCD or LED display windows.

The tail of a label-type keyboard must be carefully positioned so that the material from which it is made does not impinge on any switches.  This does not apply to keyboards based on PCB's which can have the connector in almost any location.

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