Membrane Switch Design Guide

Since membrane switches are custom designed to meet specific applications, each product will have its own criteria to meet. JRPanel has used its more than 20 years of membrane switch experience to compile some of the most critical guidelines to designing and specifying our products. The use of these guidelines will help ensure that all aspects of product design are considered as to maximize the aesthetic quality, reliability, and efficiency of the final product. 

Genral Considerations

Enviromental:

 
What temperature and humidity range will this product experience?

What types of contaminants or chemicals will come into contact with this product?

Will this product be subjected to moisture and/or U.V. exposure? 

Electrical: 

How many contact points will there be?

What type pinout or matrix will be used? (common bus, X-Y matrix)

What closed loop resistance will be acceptable?

Will electrostatic or EMI shielding be necessary? 

Mechanical:

Will tactile response be required?

To what material will the switch be laminated?

What number of actuations will this product receive?

Will actuation force be a factor? 

Appearance:

Will edges be exposed, recessed, or covered with a bezel?

Will embossing be required?

Will there be different parts to the same product? (sets)

How many colors will be needed? 

Basic Membrane Switch Construction

Graphic Design and Preparation 

Graphic Design Sample

Blueprints – Provide drawings that clearly dimension all physical characteristics including color breaks and copy.

Colors – Identify colors by using Pantone (PMS) color number or a color sample. It is important to supply the exact standard for which our color match will be evaluated. Be cognizant of how colors contrast with one another in order to maximize the legibility of the text and symbols. 

Background – Dark backgrounds and light text will provide greater clarity and show less wear and dirt.

Artwork – It is possible for customers to supply useable artwork, but they should consult JRPanel first to ensure that proper artwork specifications are met.

Borders and Outlines – Avoid outlines close to cutouts or outer edges, or circles within circles, as any misregistrations will be visually accentuated. 

Text – Block lettering provides the most legible copy. Try to use common fonts. When logos or symbols are used, it is best to supply film positives or accurate black and white artwork for JRPanel to scan. Positive letter strokes should be a minimum of .008” and .012” for negative letter stroke.

Embossing 

Raising certain areas of the graphic overlay can offer a unique look to your product as well as provide an important function.  JRPanel can emboss graphics in two ways: Metal Dome and Die Pressing. 

Metal Dome

It is a stainless steel dome that assembly in the upper circuit layer. When press the keys, it will be connected with the beneath circuit. It will have a tick sound and with a good feeling of bouncing. The life circle is about 2 million times. No need to make mould.

Die Pressing

It is embossed silver pad that on the upper circuit layer, when press the keys, it will be connected with the beneath circuit. For this kind, when pressing, there is no sound. The life circle is about 5 million times. For batch orders or too many keys in 1 membrane switch, it needs to make die pressing mould.

Creating a blueprint for a membrane switch? Don’t forget these important specifications!

Overall size of part
Keypad centers
Diameter of corners
Size and Location of Cutouts
Size and location of windows
Location of tail exit point
Location of graphic entities
Electrical schematic
Identify “pin 1”
Color specifications
Tail Length

Embedded LEDs 

As a substitute to mounting LEDs on a sub-board, JRPanel can provide membrane switches with LEDs embedded inside the membrane switch. This method can prove very effective particularly when a printed circuit board is not needed directly behind the membrane switch.
 
Due to the profile of a surface mount LED in relation to the thickness of a membrane switch, it may be necessary to emboss the graphic overlay to accommodate the thickness differential. JRPanel can use several standard LEDs for this application. 

Backer Adhesive Selection

A wide variety of pressure sensitive adhesives are available to bond the membrane switch to a substrate. Selection of the best adhesive will depend upon such factors as environmental conditions, type of substrate (metal, plastic, paint) and smoothness of the surface. In general, low surface energy materials as well as rough surfaces provide more difficult substrates for which to adhere. Here is a guideline of the surface energy of several popular substrates (in dynes/cm).