|SwitchAir Metal Domes
KEY DOME ARRAYS
Nicomatic is one of the world's fastest growing and
one of the largest manufactures of dome arrays. Our arrays are produced
in Class 10,000 clean room environments with ISO9002 certification. Our
factories are located in France, Korea, Hong Kong and North America ensuring
that we can meet your needs anywhere in the world.
The key dome array has become one of the most cost
effective solutions for providing a switching mechanism with a superior
tactile effect and feel between your equipment and the user. Pre-positioned
key dome arrays have been designed to be simple and quick to use in assembly,
just remove the liner from the array and it can be stuck straight down
to the pcb or flexible circuit.
Dome arrays offer a number of advantages and feature
- Superior tactile feel
- Enhance environmetal characteristics
- Low profile
- Avoids contamination
- Cutouts suitable for leds
Applications can be wide and varied covering any product
that requires switching inputs from the user. Dome arrays have become
very popular for use in mobile applications as they have can offer some
very positive advantages over the use of a polydome layer as highlighted
Dome array utilising N6.4 4leg 170
- Enhanced tactile feel
- Total assembly height of 0.38mm
- General tolerances of +/- 0.25mm
- Dome can be orientated with an angle between
0° and 90°
- Total weight of array of 20 domes aprox 0.45gr
- Available with or without spacer
- Wide temperature range
Ventilation is provided via the kiss cut or via chanels in the spacer
layer connecting the various dome chambers. The pcb ventilation holes
are therefor no longer required thus enabling more creativity with your
A sampling of each component is controlled to Nicomatic's
requirements before being accepted for use in our dome array production.
Arrays of domes can be produced using our comprehensive
range of metal domes (select here for
link). Our established production process's ensures:-
- Stable forces of domes
- Excellent tactile feel even after rigorous overload
- Control of dimensional tolerance
- No burrs, thus reducing wear on the substrate
- Successful and reliable automatic placement with
equipment which enables high production capacity
The standard material used is a 0.05mm polyester plus
a 0.03mm sheet of acrylic adhesive
Control and qualification of components
To ensure a high quality product wide ranges of tests
are conducted: force, tactile feel, life expectancy,electrical contact
Metal domes are characterised by a Force/Travel curve.
A typical curve is depicted below. The two curves represent the make cycle
and the break cycle when a metal dome is actuated.
- The make cycle is the higher of the two curves
and represents the force and travel of the metal dome as the dome is
- The lower curve (break cycle) represents the force
and travel of the dome as it is released
||The curve shown here does not take into consideration
effects of the keypad and the mounting
- The trip force Ft is the maximum force required
to activate the dome
- The rebound force Fr is the amount of force
applied by the metal dome during its release. If the overlay or keypad
requires more force than this during the release in order to make the
return, the metal dome will not be able to release.
- The contact force Fc shown on the curve
represents the amount of force being applied when contact is made with
the lower surface.
The dome is submitted to 3 million actuations. The
trip force and the rebound force are measured during the test and must
continuously meet mechanical and electrical requirements.
Overload test (static load)
These tests vary in the amount of force, the duration
of application of the force and the number of cycles required. The acceptance
criteria difer from the test strength. The dome must meet all mechanical
and electrical requirements during and after the test.
The rebound force of the dome is measured during an
over travel condition. Nicomatic's domes react very well.
Position of the actuator shifted from the dome
The conditions of this test are similar to the life
expectancy test. The difference is that the actuator is not located in
the centre of the dome, but maximum 1mm of teh centre. The SwitchAir dome
demonstrates remarkable robustness to this test, indeed, the dome reacts
the same as is the actuator was in the centre.
Nicomatic measures the switching signal and the contact
resistance of the dome.
As shown below, the height of the SwitchAir dome array
when assembled consists of the height of teh dome plus the thickness of
teh polyester/adhesive retainer.(N6.4 4leg 170 used in example)
|Dome array height
||Where standard sheets sizes are produced sheets
of 4, 6 or 8 arrays are delivered in dispensing boxes individually
sealed from the environment.
If you would like one of our application specialists
to visit you and talk through the different options possible give us a call
- we will be happy to help
Our tooling capabilities have been developed to offer
our customers a cost effective solution suitable for their project needs.
Prototyping samples can be supplied normally within 2-3 weeks from agreement
of specification. The option thereafter as to whether to move to a general
production tooling and produce the product on one of our specialist pick
and place machines or if the monthly requirement is substantial then tooling
can be produced for our fully automated MDA (mass dome applicator)