Best Membrane Keypad Switch For Arduino

In this review we explain what are Membrane Switches, give some product recommendations and links to software libraries for implementation. It’s easy to include a 4×4, 1×2, 1×4 or other configuration keypad for your Arduino design. The best keypads tend to use a membrane technology for low-cost, ease-of-use and simple maintenance.

We’ve seen that over the past few years, there has been a noticeable increase in the use of membrane type buttons, switches, keypad, and keyboards. The largest growth has been for devices / systems used in medical, communication, instrumentation, and appliance products.

Membrane key technology is a particularly good solution in applications where frequent cleaning or environmental conditions are an issue. They also stand up to frequent usage, and key-press life-times are excellent.

Before going into more on the technology, here are some of our favorite membrane switch keypads for developing Arduino base projects. And with the universal type inputs, your could you these with other systems as well.

Related Article: Arduino Due A000062 and Yun A000008, Two Newest Arduino Development Boards

Following the product info are links to Ardunio libraries / code for implementing a keypad.

Inexpensive Membrane Keypad

Here is just a sampling of the types of membrane switch keypads which are available through Amazon. We’ve experimented with a large number of different ones, and this is a great place to start to find just the right configuration for your project.

1×4 4 Key Matrix DIY Flat Membrane Switch Keypad, DC 12V (about $3 each)

• 5 pins, 2.54mm pitch connector, 1×4 type, 4 keys

4×4 Universal 16 Key Switch Keypad Keyboard (about $10 for 5 pieces)

• 8 pins, 2.54mm pitch connector, 1×4 type, 4 keys

1×2 2 Key Array Membrane Switch Keyboard Keypad (about $5.50 each)

• 3 pins, 2.54mm pitch connector, 1×2 type, 2 keys

1×4 4 Blue Key Button Matrix Membrane Switch (about $9 for 3 pieces)

• 5 pins, 2.54mm pitch connector, 1×4 type, 4 keys

5 Keys Matrix Keyboard Membrane Switch Control Panel (about $6)

• 7 pins, 2.54mm pitch connector, 1×5 type, 5 keys

Arduino Keypad Implementation

There are a number of excellent, open-source libraries and coding examples for implementing a keypad into your Arduino design. These can be easily modified for your particular project / application, as well as be used for other types of processors / systems.

Arduino Playground – Keypad Library: Code for a 4×3 matrix (e.g., numbers 0-9, star “*” , and hash “#”)

Using 4×4 Keypad With Arduino: Development implementation guide for a 4×4 matrix keypad, with 16 keys (0-9, A-D, *, #)

Arduino Playground – Keypad Tutorial: The Matrix Keypad How To Guide

How to Set Up a Keypad on an Arduino: Hardware and software for common 3×4 and 4×4 keypads

Membrane Keypad Technology

A membrane switch is different from a conventional mechanical switch. The following section provides a brief overview of membrane switch, their construction and types.

Membrane Switch: Basic Construction

In a membrane switch, there is a film comprised of multiple layers: static bottom circuitry, top circuitry, spacers and graphic overlay.

Generally, polyesters and polycarbonates are used for making these layers because both these materials are easy to print on, can be easily die cut and embossed, and available in a wide variety of textures.

As shown in the example diagram to the left, a typical membrane switch comprises of the following components

• Graphic overlay
• Graphic adhesive
• Top circuitry
• Spacer adhesive
• Bottom circuitry
• Backer adhesive

Once assembled, these are typically housed in a metal or molded plastic housing, for a stand-alone switch. Alternatively, the membrane is affixed directly to the equipment.

Types Of Membrane Switches
Membrane switches can broadly be classified into two categories- switches with tactile feedback and switches without tactile response.

• Non-tactile Membrane Switches: They are counted to be very reliable and economical at the same time. One of the biggest advantages with non-tactile membrane switches is that a wide variety of custom shapes and sizes can be fabricated for the active keypad areas. The operator doesn’t get a direct feedback from such a switch but this problem can be nullified by use of LED indicator or display change.
• Tactile Membrane Switches: The snap action of tactile membrane switches is readily perceived by the operator. Tactile response is achieved by dome embossing of the graphic overlay.

Conclusion

We see that membrane switch technology has continued to improve, especially in the last five years. With new advances in the films and polymers, we expect that the quality of these simple switches will trend upwards, while the price drops lower.