KEYFLEX offer a complete range of keypads to suit most applications including laser etched, multi-coloured, wear-resist coated and plastic feel keypads/keycaps.
The KEYFLEX Company is recognised as being the main supplier of conductive silicon keypads to a range of worldwide manufacturing companies, many of which are well established exporters competing in the world’s markets.
Our silicon keys are produced to exacting quality standards, with production having achieved the status of ISO 9002 in 1988. We have a good understanding of the many applications in which the keypads are utilised, enabling us to offer technical advice when considering your specific product. Where desired we offer a full 3D design and production drawing service, as well as the supply of plastic housings, graphic surrounds and printed circuit boards or membrane circuits that operate with the keypads.
The keypads can incorporate a wide range of product requirements including feel, travel, wear capabilities, aesthetic appeal, plastic keycaps and shape. Should you be considering a keypad for your prototypes, we can offer either lower cost prototype tooling or in some cases a standard layout which may only require a minimal screen cost for changing the printed detail.
How are they produced?
The most common form of keypads use carbon pills as a contact to short out PCB tracks. The pills and the silicone is placed into a mould and uses heat and pressure to form the keypad. This video demonstrates the process
Our keypads undergo extensive lifecycle testing for intensive applications and utilising long life silicones can exceed 10M operations
Alternatives to carbon pills?
Some designers are looking for a more positive tactile feel than traditional carbon pill keypads. This can be achieved by using tact switch mounted on the PCB and the stem of the tact switch is seated behind the silicone key.
One other method we use that doesn’t involve the extra costs associated with tact switches, their mounting costs or mechanical failure is the use of tactile metal domes on an adhesive layer which gives a broader design scope for key design as the force and feedback is not solely produced in the diaphragm of the keypad. The PCB cost is reduced and installation can be a simple peel-and-stick process (not necessarily required) Below is an example of this type of keypad
Laser etched keypads are produced using translucent coloured silicones with printed keytops, which are the sprayed with silicone paint. After curing the paint is laser etched to expose the translucent ink below. When backlit only the etched characters transmit light. This makes the keypads ideal for applications where excess light spillage would create problems for the user. Most colours are available for spraying including metallic colours such as silver and brass.
Below is the process of laser etching being applied to a keypad that is to be backlit
Multi-coloured keypads can allow many different key colours within the one keypad. We work to standard colour matching systems such as Pantone and RAL. In addition, we can match client supplied colour swatches in many cases. By applying the colour to the key, rather than printing the colour on the top of the key, the cost of the keypad is reduced and the risk of ink wear is minimised.
Wear-resistant coated keypads are achieved by applying a coating to the keypad after the post curing process. This means any printing or spraying are also protected by the coating. To avoid potential ink wear we recommend using a wear resistant coating in applications where the keypads will be subjected to high usage or will be used in a harsh environment.
Plastic feel keypads/plastic keycaps in some applications our clients have chosen the cost savings and the ease of assembly offered by silicone keypads, but have requested a plastic keycap feel. This can be achieved by using plastic keycaps, or by applying an epoxy coating to the keytop. In addition, thermoformed keypads can be produced where the key height is low and the key travel short.
Plastic keycaps can be produced in coloured finishes or can be clear to allow the print on the keytops to be visible. The keycaps can also be sprayed and laser etched if desired.
Epoxy coating can be left clear to display the printed ink on the keytop or can also be sprayed and laser etched. The epoxy coating can have either a gloss or a matt finish.
Thermoformed keypads are produced using polycarbonate or polyester, which is printed on the rear surface and then thermoformed to fit over the keypad or plastic insert. The ability to create small, closely pitched keys makes them ideal for small hand held appliances where a keypad’s size is critical.
What’s the difference?
The durability of keys, keycaps and their coatings are measured using an RCA abrasive wear testing machine
Testing is carried out in accordance with ASTM F2357 applying 170gms of down force to each key material and cycled through the machine. This does not give an indication of how many key presses each will withstand but shows comparative advantages of differing material.
The RCA number is the revolutions of the test machine before obvious wear levels become visible. These are minimum numbers and are purely for comparison purposes- for example we have performed tests on plated plastic keycaps and had results of RCA=2600
Plated plastic keycap RCA≥ 300
Plastic Keycap with printing and UV coating RCA≥ 200
Keypad with printing and PU coating RCA≥ 40
Matt PU RCA≥ 40
SPU RCA≥ 40
H343 and 3U RCA≥ 15
Silicon Keypad with printing and no coating RCA≥ 7
Plastic Keycap with printing and no UV coating RCA≥ 2~3
Typical design criteria for keypads- please click the images below or download the PDF file.