The first interaction with your product the customers usually have is with the graphic overlay, as a result, the graphic overlay design must be perfect. Graphic overlays should be aesthetically appealing and maintain its integrity after many years of use. Several design elements are considered to ensure the proper durability and aesthetics.

This graphic overlay design guide is intended to be an introduction to the elements that an engineer needs to consider. Sigma 6 Electronics’ engineers can do an analysis of your product. You only need to provide details about the application and  we can suggest the most ideal elements to incorporate into your design. Contact us!



The most common graphic material used in overlay applications is polycarbonate which is easy to print, die cut, and emboss.  Polycarbonate has excellent optical clarity and color stability in light or white colors and can remain clear above 10mil (0.010”); available in sizes up to 30mil (0.060) and higher.

The disadvantage of polycarbonate is that it begins to show signs of wear and tear sooner than some of the alternate materials and if a hard coat is not applied the material will be susceptible to damage from a variety of chemicals and UV light.   In most applications polycarbonate overlays will last a minimum of 100,000 cycles during life cycle testing.

A more robust material, Polyester, has superior life cycle and chemical resistance properties. Polyester shows no signs of wear at 1,000,000 cycles and is recommended for use with tactile metal domes or polyester domes.

Polyester is the most commonly used base material for circuitry since it is known for superior physical and electrical properties, .



Embossing membrane switches will enhance the 3 dimensional look and improve the feel of your graphic overlay. We recommend to emboss a graphic overlay that activates micro switches. Material embossed for buttons are 1 to 1.5 times the thickness of the base material.

We offer three types of embossing (full, dome, border). Contact a Sigma 6 Electronics sales engineer to request a membrane switch sample showing all emboss types.

Graphics are sub surface printed to overlay materials using silk screening or a digital printer. Overlay stock material comes clear or with a texture. Areas where no printing occurs become windows.

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Most overlay materials come with a manufactured or screen printed hard coat option. A hard coat will offer excellent protection for scratch, impact and chemical resistance while maintaining clarity with color and graphic detail.

An antimicrobial protection can be applied to a membrane switch’s overlay disrupting the bacterial cell wall, killing or inhibiting growth of microbes, including MRSA and E.coli. Also prevents growth of unsightly mould and mildew.

Pantone Matching System (PMS) is the most popular color standard. PMS assigns colors a numerical identifier. We can match the color of a customer supplied sample or pull the color from your digital files. Sigma 6 includes one approval stage in all quotes prior to production this allows customers to adjust colors if they choose.

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