What is touch membrane switches? (Membrane keypad Guides 2021)
Fundamentals of the Rubber Keypads
In today’s age of technology, there is a high demand for the accurate and comfortable interface solutions between the machines and human. When we design an application, the point to be noted is that it should provide the comfortable features and ease of access for the customers. The customers are liable the effective and efficient tactile functions in the use of applications. That is why modern touch membrane switches play an important role.
The membrane switches have specific performance according to the type of application. These membrane switches have the critical and specific functions for the relative applications. The design of this membrane switches show the characteristic performance related to the suitable application.
This article will narrate you the fundamentals of these membrane switches. Moreover, it will also illustrate the requirements of these switches and how they contribute the successful and effective design. This article will help you enhance the quality and reliability of these membrane switches.
Types of touch membrane switches
The touch keypad membrane switches are of two types. They can be tactile or non-tactile. However both can function with or without the graphic overlay. The tactile switches are able to give the feedback to the user for the depressed key. In this way, the user comes to know about depressing the key.
While non-tactile switches don’t have metal dome. That’s why they are not able to generate the feedback to the user about depressing the key. In general, the user’s finger receives the feedback about the depressed key in the tactile switch. On the other hand, the user’s finger does not receive the feedback for the depressed key.
Construction of touch membrane switches
The construction of a touch keypad membrane switch consists of following parts.
- Graphic overlay
- Graphic adhesive
- Dome retainer
- Dome spacer
- Bottom circuit
- Rear adhesive
Circuit Design of touch membrane switches
The circuit of these keypad switches may use the common base. They can also contain the matrix configuration in the circuits. While they may also have both of these together. The connection of these membrane switches can be established to the PCB through a cable or table. The tail is the type of connector that has the bare connection at one end.
It can also have the plastic connector housing at one end. The pitch of the tail termination varies according to the type of switch. The tail has the ability to exit from a corner or edge. It can also implant the location of the specific part. It is noteworthy that the tail cannot exit from the button area.
The backlighting design of the touch keypad membrane switches cover following three types.
- The membrane switches may have the LEDs implanted in their circuit. The equipment for the mounting of the LEDs in to the circuit of membrane switch is the pick and place unit. From the options for backlighting design, this is the most economic option.
- The other layer we use to incorporate in the membrane switches is the layer of fibre optics. This can be equally helpful in the backlighting as well as the uniform lighting.
- The third option for the backlighting design is the light guide film. It can also provide the uniform light.
Shielding Options for keypads
The most common types of the shielding options are available using the carbon ink. They can also use the silver ink or the aluminium solid. From these ones, the most expensive and economic printing option is the carbon printed option. However, the aluminium is costly but it represents many advantages over the other two types.
There are two types of the domes that are easily available and have effective performance.
These two are 4 legged domes and oblong domes. As far as the 4 legged domes are considered, they may have to diameter of 11.2mm to the extent of 25mm. It can carry out at least 3 million activations in its life duration. Moreover, they may contain the range of the activation forces in between 85g to 2000g.
On the other hand, the oblong domes may have diameter of 11.2 to 50.8mm. The range of the activation forces in the oblong domes is 230 to 450g. They can also do 3 million activations in their life duration.
During the deflection of the touch keypad membrane switches, the required component is the track. This track is implanted within the switch. When this track connects the switch keys, it displaces the air from inside. The venting process is present in the internal section. The external venting is not advisable.
Subpanel of touch membrane switches
There are several effective materials that have the important role in the fabrication of the subpanel. These materials may be polycarbonate or aluminium. The subpanels in which laser fabricates them, have the specified structure and function according to the required case.
The size of the subpanels is usually smaller than the membrane switch. On the other hand, the holes and ports of these subpanels are larger than the membrane switches.
There is a variety of the materials that are available and effective for the membrane switches. The important of these are polycarbonates and polyester materials. The membrane switches that have the graphic overlay have these materials within them.
These two materials have the advantage that they are printable on the second surface using the screen. On the first surface, they are insensitive to the chemicals and scratch. Comparing these two materials, the polyester has the wide uses due to its advantageous characteristics.
Polyester assists in the effective and efficient chemical resistance. Moreover, it can perform more than 5 million actuations in its life time. On the other hand, the polycarbonate material does not provide as effective chemical resistance as the polyester. They can also perform only 100000 actuations that are much less than those by polyester.
Touch membrane switches Colour Matching
For the purpose of color matching, the Pantone matching system is the most important one. It has the ability to have advantageous characteristics in the applications involving the graphic art.
The digital presses can match the custom and transparent colors with the high efficiency. However, the basic mechanism is different and unique for the opaque and transparent colors.
It is noteworthy here that to compare the colors of the graphic overlay to the neighboring colors is quite a difficult task. That is why the art color matching has the priority over the graphic overlay color matching.
The necessary and crucial requirement for the color space is the availability of the control of a color to match. Once this control is achieved, we can match the custom as well as transparent colors.
Touch membrane switches Embossing
The pillow and rim designs of the touch keypad membranes are mostly available for the polyester and polycarbonate layers. For this purpose, we need a die set from a male or a female. We can synthesize and design the embossing dies with the help of specific tolerance ranges.
The windows can be display windows and LED windows. The display windows are transparent, with clear or color matching. The LED windows may have the transparent or translucent matching. The property of the transparent color is that it is clear.
Moreover is has usage and utilization in the filtering of backlight displays. On the other hand, the translucent color has the wide applications in the removal of the blooming effect.