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How does internal structure of Rubber keypad membrane switch work?

How does internal structure of Rubber keypad membrane switch work?

Sep 15, 2021

Understanding rubber keypad membrane switch

Membrane switches usually follow compression molded switches technology. Rubber keypad membrane switch uses silicon that is pressure molded.

Rubber keypad membrane switch

Examples of membrane switches

  1. First and foremost, microwave oven operation unit
  2. Secondly, electric pot operation unit
  3. Above all, washing machine operation unit

We collectively classify membrane switches as “seat keyboard switches.”

Membrane switch structure [FM series]

The membrane switch has a structure of “surface sheet”, “spacer”, and “contact sheet”. Screen-print conductive ink paste on the upper and lower contact sheets and attach them with spacers in between. Operating principle of membrane switch is needed to be understood.

When the upper contact sheet is pushed and the membrane switch meets the lower contact sheet through the hole of the spacer, it conducts, and the switch is turned on. Furthermore, this is how a rubber keypad membrane switch operates.

Rubber keypad membrane switch materials

  1. First, film material common
  2. Second, PET (polyethylene terephthalate)

(same as the resin common in PET bottles)

  1. Moreover, printing contacts Uses conductive ink paste (carbon, silver, etc.)
  2. Furthermore, click-feeling type structure
  3. Lastly, the click-feeling type uses a “metal disc” to give a click-feeling.

Card insertion type in rubber keypad membrane switch [FM]

It is a card insertion type. Print letters and numbers on the attached card, then insert it between the main body and the protective film and glue it. Above all, rubber keypad membrane switch is effective for confirmation when evaluating prototypes.

Features of NKK Switches Membrane Switch “FM Series”

The features of NKK Switches’ membrane switch “FM series” are as follows.

  1. First it is thin (about 1 mm)
  2. Second, high degree of freedom in design (available as a custom product)
  3. Moreover, its freely arrange keys
  4. For the card insertion type, the display unit easy to manufacture by the customer.
  5. Furthermore, it has simple drip-proof properties
  6. Additionally, with or without click feeling is easy to select
  7. To attach to the housing, just stick it with the adhesive on the back side
  8. Point illumination type is easy to select in rubber keypad membrane switch

Recommendations for   when ordering “FM series” custom products

For custom products, the points are as follows.

(1) Design

  1. Number of colors on the surface sheet
  2. Size, key pitch
  3. Position and length of the tail (wiring lead from the membrane switch)
  4. Above all, circuits, and pin assignments

(2) Switch (click) type

  1. Firstly, no click (with or without embossing)
  2. Secondly, discs click (with or without embossing)
  3. Lastly, embossed click (those with a click feeling by processing the sheet without a disc)

(3) Other

  1. First, LED mounting
  2. Second, special requirements such as durability and operating temperature range

Rubber keypad membrane switch involves all of these above-mentioned aspects.

What is a mechanical key switch?

A mechanical key switch is a mechanical switch that has a tactical switch mounted on a printed circuit board and a separate operation unit and surface sheet mounted on it.
Achieves high durability and good operation feeling.

Features of the seat keyboard switch mechanical key type “FK series”


The features of NKK Switches’ mechanical key switch “FK series” are as follows.

  1. Since it uses a tactical switch with a sealed structure, it is highly reliable, such as dustproof.
  2. Soft and reliable operation feeling in rubber keypad membrane switch
  3. Moreover, selectable from non-illumination, point illumination, and surface illumination
  4. Also, other electronic components can be mounted on the board on which the switch is mounted
  5. Lastly, it supports a wide range of operation panels, assembly products with cables, etc.

Recommendations for buying rubber keypad membrane switch from FK series”

Following points are to be kept in mind when ordering “FK series” custom products

(1) Design

  • First and foremost, the number of colors on the surface sheet
  • Additionally, size
  • Also, with or without embossing
  • Lastly, circuits and pin assignments

(2) Other

Features of rubber keypad membrane switch

NKK’s seat keyboard is ideal for small-lot, high-mix, custom-made products.

Mechanical key type A mechanical key (tactile) switch is placed under the surface sheet to achieve high durability and a good operation feeling.
Print contact type Illuminated type and non-illuminated type with LED arranged, with or without click feeling with a click feeling. Furthermore, there are12 types of standard sheets.
Printing contact type Card insertion type A simple surface sheet is completed simply by inserting a card (paper) on which characters and figures are written. More importantly, it rubber keypad membrane switch is ideal for prototyping studies.

Mechanical key type; rubber keypad membrane switch overview

Widely compatible with operation panels, display units, assembly products with cables, etc. The contact part supports various variations such as tactical switches, push button switches, and contact lovers.

Tactile switch First, click feeling of operation
Pushbutton switch Second, good operation feeling, with stroke
Contact rubber A feeling of operation


Print contact type in rubber keypad membrane switch

LED point illumination and non-illumination, with and without click, terminal pitch 1.0mm
with LED and without LED. Click feeling can be selected depending on the presence or absence of a metal disc.

If you wish, we will manufacture such keypad membrane switch with your own design.
From small lots to large lots. Supports a wide range of products such as operation panels / display units / assembly products with cables.

A comprehensive insight on flexible wiring boards

Based on the questions we received from our customers, this time we will continue to talk about flexible wiring boards. In the second part, we will introduce the structure and features of the membrane. Please use it when designing the equipment.
Rubber keypad membrane switch 2021

Continuing from the previous introduction of FPC / FFC, we will continue to look at flexible wiring boards this time for rubber keypad membrane switch. I would like to introduce the features of the membrane that I could not touch last time.

Free wiring pattern in membrane switches

Since the conductive part is printed, it is possible to draw a free wiring pattern and the degree of freedom in shape is high.
However, its processing accuracy is inferior to that of FPC, and since it uses silver, which is prone to migration, as the circuit material, it is not suitable for narrow pitches such as FPC.

Applications of rubber keypad membrane switch

Membranes are mainly common in touch panels and switches based on capacitance and mechanical systems, rather than signals and power supply circuits in keypad membrane switch.

Conductivity is achieved by bringing fine conductive pastes close to each other or in contact with each other. Specifically, there are applications such as laptop keyboards, touchpads, and consumer electronics switches. In recent years, its use seems to have expanded to in-vehicle use.

 Heat resistance in rubber keypad membrane switch

The membrane screen prints the wiring on the PET material. As introduced last time, FPC covered with polyimide material can be reflowed, but since the membrane uses PET material, it does not have heat resistance until reflowing is possible.

Therefore, it is not possible to reflow with the connector on rubber keypad membrane switch, and it is not possible to use a narrow pitch connector that fits the two pieces of the socket header. Even with the same flexible wiring material, FPC, FFC, and membrane have different structures and are common for various purposes.

Significance of mechanism design in membrane connections

It is necessary to design the mechanism while recognizing each feature. To respond to such various variations of flexible wiring materials, Panasonic can also support connectors for membrane connection. Please feel free to contact our sales office or call center.

How was it? We introduced the features of FPC, FFC, and membrane in the previous and this time. With these soft, bendable, and thin wiring boards, you have more freedom in your design. Bending wiring board, a technology that is hard to come by!

Features of rubber keypad membrane switch

Membrane has come to be called a ” rubber keypad membrane switch ” because it is a sheet switch that applies thin film printing technology. Currently, membrane switches are common not only as industrial equipment for special purposes, but also as switch electronic parts for various electronic products such as microwave ovens.

When it comes to replacing the operation panel that common to use a general switch with a membrane switch, do you have any concerns about “how to illuminate a thin membrane switch? “The key can be illuminated even with a thin membrane switch.

 Advantages of rubber keypad membrane switch

Rubber keypad membrane switch offers you the following benefits

  1. First, the customer’s free image can be commercialized
  2. Second, a personal computer interface is also available
  3. Support of special operations such as shortcut keys
  4. Membrane switches can also be equipped with electrical components such as LEDs and resistors.
  5. According to keys, the number of pins at the connection (tail) may increase even in a matrix circuit
  6. Also, inkjet printing and standard keys are cost effective and highly practical approaches
  7. Above all, if it is a membrane switch, it can be curved according to the housing

Rubber keypad membrane switch configuration

From design to production of rubber keypad membrane, is the track of this configuration. The design and the size and position of the key can be freely designed. Furthermore, it has excellent dust and drip proof properties, and depending on the structure, it can be made waterproof.

 Membrane switch around water

There are many inquiries about using the membrane switch around water. Since the waterproof structure complete by assembling with the housing, we will
propose the optimum proposal by the design technology cultivated by our company according to the customer’s application.


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