Over the past few years, designers and engineers who incorporate keypads such as membrane switches or silicone rubber into their HMI devices, have likely heard the terms hybrid keypad, or hybrid membrane switch. This is especially true if they’ve worked with SSI Electronics. As a company who is always striv-ing to add new and exciting bits of technology to our repertoire, we wanted to give our customers some new options, all while utilizing our core technology: Membrane Switches.

A typical membrane switch has a some-what 2D front panel with either flat or slightly raised(embossed) keys for the user to interact with. Many industries require this easy-to-clean surface, as there are minimal areas for bacteria to germinate, dust to collect, and also very few areas for moisture to ingress into the electronics. While there have been many advancements in membrane switches since their inception about 35 years ago, arguably none are as im-pressive from an aesthetic point of view as the hybrid keypad design. The hybrid approach gives users a unique look and feel, as it embeds a rubber keypad into the switch.

Typical Membrane Switch

The hybrid approach gives users a unique look and feel, as it embeds a rubber keypad into the switch. 

Dave Kerkstra User-Interface Specialist

Published on September 14th, 2017

You may be asking, “How is this different from a typical rubber keypad?” Typically a rubber keypad, or conductive rubber keypad utilizes a carbon pill on the back of the key which would interact with interwoven fingers on a PCBA. While this method is tried and true, it does require the circuit board to be directly behind the keypad, thus creating some design con-straints. It also often requires designers to de-velop some type of custom bezel to go over the keypad to hold it in place. In contrast, the hybrid model utilizes high strength, pressure sensitive adhesives to best adhere to your substrate, thus intricate and expensive bezels are no longer needed. By utilizing a hybrid keypad, you get the great look and feel of the raised rubber keys, but with the freedom of a tail which plugs into a header on your board. This tail is customizable and can be any shape or length the customer would like. Tac-tile feel can also be maximized by combining a well designed boss on the back of the rubber to mate with an appropriate metal dome.

Membrane switch circuits are known for being highly moisture-resistant, impact resistant, and reliable, offering over 1 million actuations under normal circumstances. In other words, when you combine the already protective properties of silicone rubber with a robustly designed membrane switch, you’ve got an incredibly solid and tough HMI. Want to explore the option of integrating a hybrid approach to your existing keypad? Or wondering what the cost premium is over a more typical membrane switch? Let’s talk.

Email us at sales@ssi-electronics.com, or call us at 1-800-866-8510.

Hybrid Membrane Switch

Typical Rubber Keypad Design w/ Carbon Pills