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Membrane Switch Design
Guide
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Introduction Membrane switch technology has become a reliable front panel solution where environmental concerns or frequent cleaning are an issue. The sealed nature of the technology coupled with its reliability and ability to offer tremendous aesthetic flexibility make it the solution of choice for many industries. The success of any membrane switch design effort is greatly enhanced by effective communication between the design engineers and the membrane switch vendor. A mutual under
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specify type styles, colors, and sizes of all copy. Artwork should be provided to us for all logos or special symbols. We use the latest version of Autocad with Autoscript to generate our drawings and artwork. It is helpful for customers to supply us with an Autocad DWG file, or as an alternate, a DXF or IGES file. Always provide Holland Nameplate with a hard copy drawing as well. Proofs of the artwork will be sent for approval to our customer prior to production. Color Matching
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Ultraviolet Hardcoats The most durable hardcoats are those that are cured by exposure to ultraviolet light. These coatings are called UV hard-coats. Hardcoats can be selectively added to many of the materials to produce parts with a velvet textured background, and gloss or anti-glare windows. Embossing In many applications it is desirable to emboss or hydroform the keys of a switch. The phrase “Plateau Embossing” is used to describe keys that are raised and flat on the top. The t
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switch. Standard tolerances should be +/- .015". Tolerances of +/- .010" can be held on critical dimensions such as the perimeter or cutouts. Hole center to hole center tolerances of +/- .005" can be held. Tolerances on very large parts will be greater. Tighter tolerances can be held by laser cutting or with the use of hard tooling. The switch layers under the overlay will typically be fabricated smaller than the overlay. This allows for die cutting and assembly tolerances. All layers will
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considered when specifying shielding requirements. Tail Exit Point Flexible membrane switches are connected by means of a flexible tail that is cut from the circuit material. We have a great deal of flexibility in selecting the exit point. The tail cannot exit under or within .125" of the active keypad area. Interconnect The flexible tail that exits a membrane switch usually has single row traces on .100" centers. This tail can be connected to a circuit board with many different
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Creasing of Flex Circuits In many applications the tail of a membrane switch needs to be bent at or near the exit point. Extreme caution should be exercised when bending flex circuits. While it is likely that continuity will be maintained in a trace that is creased sharply, the trace will most likely be damaged, and be a potential area of future failures. It is recommended that a .010" radius be used to wrap the flex tail around if a bend needs to be put into the tail. A folded piec
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sense to consider polyester domes if the total dome usage per order is expected to exceed 2500. A drawback of polyester domes is that they tend to relax and lose their tactile feel at elevated temperatures and are not recommended for applications that will experience temperatures above 55˚C (131˚F). Actuation Force The customer may specify the switch actuation force. Typical actuation forces range from 6 to 24 ounces. Polyester domes usually have greater actuation force than do stain
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-45˚C to + 75˚C (See notes on polyester domes) Life Cycle Testing Holland Nameplate performs life cycle testing to insure that our customers have a realistic expectation as to the typical number of cycles a particular design can endure. Any specific life requirements should be communicated to Holland Nameplate’s engineering department before the design begins. Windows The overlay materials used in membrane switches begin the process clear. Colors are screen printed on the back of t
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that will have insertable legends. An oversized pocket is put behind this clear area so that the legend card can be inserted and seen through the window. The entire overlay has the same texture, which helps hide the fact that legends are being viewed through a window. The diffusing properties of the texture are not a problem for viewing the legends because the legend cards are held directly against the overlay by the pocket. It is also recommended that the background color be different tha
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Always clean the surface before installing a membrane switch. If alignment is difficult, we recommend that you remove a small corner of the backing, align the membrane switch, stick the corner down, bend back the membrane switch and remove the rest of the liner. NEVER bend a membrane switch in an LED or dome area. After the membrane switch is correctly located, rub it down with firm pressure. The adhesives we use are called pressure sensitive adhesives because they need pressure to insure a
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of the membrane switch. A sample of a simple drawing of a membrane switch is included in Appendix “C”. Appendix “D” is a glossary. Holland Nameplate Overlay Material Guide Appendix A Product ID Manufacturer Base Film Hardcoat Finish Embossable UL Rating Texturable Thickness Melinex 561 ICI Polyester No Gloss Yes No Rating Yes .005" - .010" Autotex2-V Autotype Polyester Yes Velvet Yes 94-HB Yes .006" - .008" Autotex2- Autotype Polyester Yes Velvet Yes 94-HB Yes
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Holland Nameplate Membrane Switch Checklist Appendix B The following items need to be communicated to Holland Nameplate before an order can be processed. ___ Mechanical dimensions of the finished part ___ Tolerance specified (+/- .015") Type of switch ___ Non Tactile ___ Tactile with stainless steel domes ___ Tactile with polyester domes Tail details ___ Tail exit point ___ Tail length Tail termination ___ Berg Clincher ___ AMP ___ Solder Tabs ___ Exposed silver for
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___ Customer Specified Shielding ___ None required ___ Printed silver grid ___ Printed carbon ___ Aluminum foil ___ Other ________________ Overlay Material ___ Velvet textured polycarbonate (8B35) ___ Gloss polycarbonate with hardcoats (8010) ___ Velvet textured polyester with hardcoat (Autotype) ___ Gloss polyester with hardcoats (Autoflex) ___ Other _________________ Logos and special graphics ___ Customer supplied ___ None required Windows/Lens coating ___ V
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Embossing ___ Key rims ___ Plateau ___ LED windows Hydroforming ___ Key rims ___ Plateau ___ LED windows Insertable legends ___ Not required ___ Specified Support panel ___ LED windows ___ Not required ___ Drawing included with material specified Artwork ___ Holland Nameplate generated ___ Customer supplied (attached to order) ___ Colors specified 15
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Color matching ___ Custom (samples supplied) ___ Pantone Matching System ___ Federal Standard No. 595a ___ Copy size, style, and location specified Switch Sealing Requirements ___ Standard splash resistant ___ NEMA 4 Switch Venting Requirements ___ Standard internal venting ___ Externally vented 16
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Membrane Sample Appendix C 17
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