faq-1

Which types of foil keyboards exist and which one is suitable for my application?

The follwoing 3 basic types with their variants have crystallised, they have proven of value in practice and are very long-lived.

In the following, you will find a comparison of the different types from our point of view:

1.) FOIL KEYBOARDS, with or without tactile feedback

Assembledon a flexible circuit

Advantages

very interesting price-/performance ratio
low one off costs
easy assembly by simple gluing on
can even be used on slightly bent/curved surfaces
very flat execution possible
various sizes of snap domes possible
no adjusting of the tactile performance required
clearly defined shifting travel
good tactile performance made possible by snap domes
alternating lettering possible by means of slide-in strips
the cable for the electric adaptation is integrated
SMD-components such as LEDs, resistors ... can be integrated
(FOILtronic®-technique)
high temperature range

Disadvantages

additional stabilisation with support plate/housing necessary
evaluation electronics have to be be placed on an additional circuit board
night design possible only by means of EL-foil or flexible light guides
individual defective components cannot be replaced in repair case
relatively large minimum distance between the keys

2.) FOIL KEYBOARDS ON PRINTED CIRCUIT BOARDS:

The foil keyboards are mounted directly on thefront side of the printed circuit board equipped with contact pads for the snap domes.

Advantages

the printed circuit board can additionally be assembled on the rear side (e.g. evaluation electronics), thus interesting price-/performance ratio
compact construction
printed circuit board is support plate at the same time
gold-gold-contact possible
various sizes of snap domes possible
alternating lettering possible by means of slide-in strips
very robust
constant tactile performance, no time-consuming adjustment
clearly defined shifting travel
high temperature range

Disadvantages

relatively high one off costs
night design possible only by means of EL-foil or flexible light guides
relatively large minimum distance between the keys
individual defective front side components cannot be replaced in repair case,
the replacement of rear side SMD-components is very time-consuming
for the electric adaptation, a plug-in connector and an additional cable are required

3.) SHORT STROKE KEYBOARDS:

So-called short stroke keys are assembled on a printed circuit board. This assembled printed circuit board is screwed with thread bolts onto a support plate foil-clad on the front side.

Advantages:

gold-gold-contact possible
easy realisation of night design and/or status display
(area- and/or spot illumination by means of integrated LEDs and light guides)
key illumination with changing colours possible
in repair case, keys can be replaced individually
good tactile performance, can easily be operated with gloves
alternating lettering possible by means of slide-in strips
the printed circuit board can additionally be assembled on the rear side (e.g. evaluation electronics)
high temperature range

Disadvantages:

high required space (installation depth!)
relatively high piece price
high one off costs
high assembly effort, especially to adjust a constant tactile performance over the whole of the keypad
danger of damage in the area between key head/-cap and recess in the support plate
for the electric adaptation, a plug-in connector and an additional cable are required

In addition, we can provide you with our customer information brochure KDI „Comparison foil keyboard – short stroke keyboard“ upon request.

We will be glad to help you with selecting the optimal keyboard system for your application - please contact us.