Protolab has spent more than three decades innovating and designing engineering HMI Input Touch Devices Design. It is the core of our business, we do productions in-house through all processes quality solutions, and deliver on time. Protolab is a global leader in the design and manufacture of HMI Devices. Membrane Switch Keyboards, Hybrid Membrane Keyboards, Haptic Technology Keyboards, Capacitive Keyboards, Vandal Resistant Keyboards, Backlight Keyboards, Metallic Keyboards, Industrial Keyboards with Trackball / Touch Pad, Silicon Rubber/Elastomeric Keypads, and many Integrated HMI Input Devices Solutions

Types of Membrane Switch feedbacks and its construction

  1. Non-tactile Membrane switches:

The assemblies are made up of a variety of conductive pads and substrate-based, usually open momentary contact switches that have been printed or etched, and plated. There are two contacts and a laminated spacer dividing. The top contact closes the switch when the switch is depressed, and the release pressure opens it. You will see the LED light turn on or hear a beeping sound to confirm that you have activated the control board. It provides a feather-soft touch sensation when the key is pressed.

Tactile Membrane switches

  • Metal Dome Switch:

The most popular type of switch is the metal dome switch since it gives the user feedback after pressing a key. When a user actuates the key of a tactile membrane switch, the metal dome embedded in the switch press on a conductive footprint, activating a desired action.  Application areas for tactile membrane switch technology include industrial automation, hospital beds, military-grade goods, public utilities, aviation, and many more.


  • Polydome Switch:

The layer of a Polydome switch is made of polyester (PET) material, and it is comparable to non-tactile membrane switches. To provide a tactile sensation and produce a click sound when the key is pressed. The Polydome is embossed into a spherical/round shape and layered above the contact layer or the conductive ink in the to contact layer is formed into a Polydome. The middle layer of the overlay and FPC/PCB are the terms used to describe this.  Polyester domes are manufactured on a single sheet and require embossing, making them more cost-effective only in high-volume applications. At room temperature, it is more ideal; but, when it is cold or hot, it is more prone to crack or soften and become flat. 

Printing Copper or Silver Conductive Ink on substrates is the fundamental method for activating keys in flexible membranes. Electroplating copper traces on circuit boards with layers of tin or gold over a nickel barrier coat is similar to PCB-based membranes.

How does a metal dome work?

Pressure-sensitive adhesive tape is used to secure the metal dome array sheets over the contact points on a PCF (Printed Circuit Film) or PCB (Printed Circuit Board). The metal domes are at ease, resting on the outer edge of the main roadway.

When you push the key, the metal dome flexes, connecting the anode and cathode. The switch operates in this way. They work in the following manner: Printed circuit board placement for the metal domes is positioned using pressure-sensitive adhesive tape. The domes collapse when they are pressed, making contact with the secondary channel and shutting the circuit.                                 

How do you know which feedback is best for your application?

Globally, HMI input devices are designed based on the specifications and applications of front-end users. If the product is intended for industrial use and will be used in a controlled environment by the operator, a non-tactile membrane is recommended. When operating the system on the shop floor with gloves in extreme temperatures and harsh environments, a dome with a higher force and a loud click tactile feedback is recommended.

Protolab engineers will similarly listen, understand, and collaborate with you to determine which feedback (Tactile or Non-Tactile Keypads) is best for your application. Non-tactile or Metal dome membrane keypads are recommended by Protolab since it gives higher reliability in extreme temperatures. Polydomes are recommended only on a thorough understanding of applications and product life cycles.


4 Leg Metal Domes

Manufactured and qualified as per ASTM F2592-16

 RoHs Compliant Stainless Steel with Nickel Plating and with Gold Plating

Operating: -40°C/ +105°C

Contact Resistance: < 100 mOhm

Life expectancy, 1 million cycles

Can be customized on request                                                                                                                                                                                    

SIZE 6 mm 4L                     8.4 mm 4L 10 mm 4L 12.2 mm 4L
TRIP FORCE 170g  220 g 220g 280g 340g 400g 220g 280g 340g 400g 220g 280g 340g 420g
REBOUND FORCE (±30 gr) 70 90 90 130 150 90 100 85 90 100 120
CLICK RATIO (%) 40-70  50-80 40-70 50-80 40-70 50-80 60-80 60-85 40-70 50-80



 At Protolab, we understand the critical role that Tactile and Non-Tactile Keypads play in the functionality and user experience of your products. Our commitment to excellence, precision engineering, and customer satisfaction sets us apart in the industry. Choose Protolab for keypads that not only meet but exceed your expectations, elevating the performance and aesthetics of your products.

For inquiries or to discuss your keypad requirements, please contact us.