Custom keypad membrane short cuts – The Easy Way

Custom keypad membrane keypads are the control elements of electronic devices and, if they are well design, they can be an excellent showcase for them, contributing to market success. An aesthetic, readable and well-functioning keypad is a very important factor that the customer takes into account when making a purchase decision.

Custom keypad membrane – How to design without errors?

It’s worth spending a bit of effort to design, fabricate, and assemble the foil keypad well. In order to avoid basic mistakes, the following rules should follow. The design keypad should adapt to the conditions in which the electronic device can control it. It is to operate and should construct as to meet the functional conditions for which it is to intend.

Fig. 1. Properly design window above the display

Making a good keypad is always a compromise between technical possibilities and reliability and price. It should remember that the simpler the design, the less reliable and cheaper the keypad. For example, the use of embossed keys instead of flat keys reduces the number of key operations by an order of magnitude.

On the other hand, it improves the intensity of its “feeling” when pressing, and thus the quality of service. However, it raises the price of the custom keypad membrane. The most common mistake made when specifying the technical requirements for a keypad is to include all possible technical solutions in it.

Membrane keypad structure

This approach not only makes the performance of the keypad more expensive, but may even make it difficult to use in some circumstances.

A very important element in the construction of the keypad is the precise definition of its shape and external dimensions. A keypad that is too large cannot be properly mounted on the device housing, because it will not fit into the housing recess or will protrude beyond its outline.

Low resolution raster graphics

Custom keypad membrane that is too small will leave large gaps between it and the housing, which may result in asymmetrical installation. This will be shown as a gap of varying width between the keypad and the case. The human eye detects differences in the width of such a gap at the level of approx. 0.1 mm and perceives it as unsightly asymmetry.

An important element is the correct dimensioning of the window size for the display and determining its position on the keypad. Wrong dimensions may obscure the displayed information or reveal the display elements that we want to hide under the keypad. This problem illustrate in Figures 1 and 2.

Functional graphics of custom keypad membrane

The key issue for obtaining the correct functionality of the design custom keypad membrane is the correct graphics of its facade. In this case, it is not about the aesthetic values, which depend on the imagination of the client and users, but about designing the graphics in such a way that it is legible in the operating conditions of a given device.

Correctly selected contrasts

The colors must select so that the legibility of the information on the facade is satisfactory, for example. When working in a darken room or in full sunlight. Since, we prepare graphic designs using a computer.

It is important to be aware of the fact that the colors display on the monitor is much more contrasting than those printed on the foil when selecting colors… Also, do not insist on using backlit keys in custom keypad membrane for devices that will work only in brightly lit rooms. Such a solution, apart from the high price of the keypad, will not improve its functionality.

Preparation of the keypad production

The important element of the preparation of the keypad production is the preparation of files intended for printing the facades in the correct resolution. Too low resolution may cause that the printed graphics will have “jagged” lines and will be difficult to read.

The same façade, print in the correct resolution, is, custom keypad membrane due to their design, design to work in difficult operating conditions. Properly construct, they are resistant to climatic, chemical and mechanical exposures and high dustiness.

This means that electrical circuit paths should be as far away from the edge of the keypad as possible. This also applies to the lead strip, which is not recommended to be placed on the edge of the keypad.

What is the Installation process of keypad?

Even the best custom keypad membrane can destroy by sticking it incorrectly on the housing. The sticking process is irreversible. The keypad cannot be peeled off and glued on again. This operation must be performed perfectly. To avoid sticking errors, follow these rules:

• Degrease the housing surface in the place where the keypad attach ,
• Peel off the protective paper from one edge of the keypad to a distance of approx. 1-2 cm and fold it parallel to the other glued surface of the paper,
• Carefully put the lead strip through the hole in the casing. So, it does not bend or stick to the keypad, remembering that the minimum bend radius of the strip must not be less than 2 mm,
• Determine the correct position of the keypad pressing it against the housing from the side of the non-peel security paper,
• After the keypad “position” correctly, stick it to the base from the side of the peeled security paper,
• By gently tilting the non-stick part of the keypad, remove all the security paper. (bending the keypad too much will bend the contact plates and damage the contacts of the buttons),
• Glue the rest of the keypad, pressing it from the side already glue. So, as not to leave air between the custom keypad membrane and the housing.

Electrical circuits of custom keypad

In order to meet our expectations in this regard, they must construct in such a way that they separate the electronics. It is contains in the housings and their layers with electrical circuits from external influences to the maximum extent. This effect will be the better, the wider the adhesive surface on the outline of the custom keypad membrane in the layers containing electrical circuits.