There are a plethora of design choices, materials, and other considerations to weigh in membrane switch design. Even the most well-thought-out plans sometimes aren’t as functionally adequate when they’re brought to fruition, making membrane switch prototypes a critical component of the overall design process. By first creating a prototype, the look, feel, and functionality of the final product can be truly evaluated in near real-world conditions. Ideally, the prototype is as close to the final product as possible, leaving only a few minor tweaks, if any adjustments are necessary at all.
For these reasons and more, an experienced membrane switch design team is invaluable to product manufacturers. It’s not cost-effective in terms of time or money to produce dozens of prototypes, each with minor improvements over the last but still falling short of the ideal product. The following outlines the basic considerations that should be weighed throughout the membrane switch prototype design process.
Membrane Switch Materials and Substrates
From rubber keypads to fully integrated, turnkey assemblies, there are a variety of materials and substrates to consider based on the type of membrane switch assembly you require and your product’s specifications. Membrane switches range from PCB membrane switch keypads to copper flex circuit membrane switches, silver flex circuit membrane switches, DuraSwitch and even touch screen options.
Rigid support backers, such as aluminum and FR4, are sometimes desirable to provide structure and rigidity to your membrane switch assembly. Materials and substrates play an integral role in the ultimate functionality of your product, offering tactile feedback, texturing, and other elements that, combined, produce the desired look, feel, and functionality. The careful selection of materials should be considered heavily in the design of every component, from selecting rigid backers to choosing the appropriate substrate (such as polyester or polycarbonate) for the graphic overlay.
Membrane Switch Backlighting
Backlighting is an important consideration in membrane switch prototype design. For products that may be used in dim lighting conditions, backlighting adds usability to a product’s user interface.
There are several backlighting options that may be used in membrane switch prototype design, including embedded LEDs, fiber optic backlighting, and electroluminescent (EL) backlighting. Each type of backlighting offers pros and cons, such as durability and ease of replacement. Other considerations include the ease of implementation given the design requirements and layout.
The graphic overlay is the visual interface component of a membrane switch assembly, providing the look and feel of the final product. Graphic overlays can be screen printed or digitally printed, based on the desired effects such as colors, shading, three-dimensional graphics, and other considerations.
Digital printing provides some key advantages in the printing of graphic overlays. In addition to a broader range of effects, including photo-quality printing, digital printing eliminates the added expense of films and screens which are required for more traditional printing methods, such as screen printing.
Textures, embossed areas, transparent windows, backlighting, and dead front or white front images are all considerations in designing the graphic overlay component of a membrane switch assembly.
Tactile feedback plays an increasingly important role in product usability, as tactile feedback options have evolved from the traditional feedback provided by standard keypads to a variety of feedback options with varying actuation force requirements. As such, tactile feedback is an important consideration in membrane switch prototype design and this single consideration can make or break a product’s success on the market.
Tactile feedback can be created with the use of stainless steel domes and other structures embedded in the membrane switch assembly. If tactile feedback elements will be used in the membrane switch prototype design, this impacts other design considerations such as overlay thickness. An overlay that is too thick may reduce the tactile feedback provided by domes, producing an effect other than the precise effect desired.
Membrane Switch Circuit Layers
Many product manufacturers believe that the graphic overlay component is the most important component of a membrane switch assembly. While the graphic overlay provides the look and feel of the product, the visual interface through which the end user interacts with and controls a device, the graphic overlay is ineffective without the proper underlying components that provide the functionality and reliability necessary for the product to work as desired.
The circuit layer component, therefore, is equally as important as the graphic overlay and other components in providing the final form and function of a membrane switch assembly. It’s the circuit layer (or layers) that enable the device’s connectivity. Poly domes are sometimes integrated within a circuit layer to add tactile feedback, and the circuit layers contain conductive inks and dielectric inks printed on a polyester backer, offering core functionality and/or serving as an interconnect to controller printed circuit boards (PCBs) or other electronics.
Electromagnetic Interference (EMI) and Radio Frequency Interference (RFI) are two terms that are sometimes used interchangeably. Both refer to disturbances that have an impact on the functionality of an electronic circuit, which, in the most severe cases can lead to a complete wipe-out of data. EMI/RFI shielding is a process that protects circuits from this interference, ensuring the longevity of a device by reducing interference through the use of magnetic or conductive materials that block the field.
EMI/RFI shielding is often used in membrane switch assemblies in order to prevent outside interferences from other devices or influences from impacting the product’s functionality.
Within these considerations and others are a multitude of specifications and additional considerations. Choosing the right materials, components, and design options for a membrane switch prototype depends on product specifications, space constraints, typical use environment, end user characteristics, and a variety of other variables. The many elements, components, and options available can quite simply be overwhelming even to experienced product manufacturers.
Working with an experienced membrane switch design team to select the right options for your membrane switch prototype design will result in a prototype that closely matches the desired final product. An experienced design team can speak to the practicality and ease of implementation of various options within the context of your product’s usage environment and other requirements. When you consider the many variables during the prototype design phase, your membrane switch prototype will be well-suited to serve the purpose of identifying nuances and tweaks that will ultimately result in a perfect final product.
Looking for membrane switch product samples or would you like to set up a free design consultation? You can call us directly by phone (216) 475-6704 or email Customer_Service@Pannam.com