China Green Color Backlighting Keypad

RSP Inc.
is your trusted source for membrane switches, EL lamps, plastic injection
molding, rubber keypads, turn-key assemblies and contract manufacturing.
We have over 50 years of manufacturing and design experience
. We have domestic capabilities for laser cutting
rapid prototype membrane switches and producing medium-sized production runs at competitive pricing. We
have offshore production capabilities for a variety of jobs large and small offering world-class pricing.
The top layer of a membrane switch is the graphic interface between the user and the machine. While other
layers are essential to overall performance, it is a well designed and attractive graphic layer that impresses the
user first. The other layers of the membrane switch need to support the graphic layer by providing the qualities
and functionality you need.
RSP Inc.
works with each customer to design the optimals witch that meets your
needs. We can maximize a
switch for appearance, functionality and price. RSP Inc. prides itself on testing each switch to your specifica
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tions so that there are no failures in the field.
The membrane switch can be the most important part of a product; do not trust the design and construction to
just any supplier.
Membrane Switch Design Guide
Generally, for excellent tactile feel in a switch with stainless steel domes we recommend on overlay material
thickness of between .006¡° and .008¡±. Thicker overlays will decrease the tactile feedback and thinner material
will decease the life.
One of our most commonly used materials in the construction of the top layer of a membrane switch is Autotex
V8 for indoor use and Autotex V8XE for outdoor use. In testing and field experience, this material has proven
itself to be superior. When comparing other membrane switch quotes, make sure you compare not only the
price, but the types of material being used. RSP Inc. puts the type of material being used right on the quote.
Textured Background
The surface texture can either be printed by RSP Inc. or supplied and the material by its manufacturer. Hard
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coat textured materials are more durable than printed textures. Extended use keypads should avoid having a
printed texture, satin, or glosses. When a material is used that has a hard coat texture (like Autotex V8) a
window is ¡°wetted out¡± from the texture.
A wet out window is the printed area where a clarifying ink is used to create a clear window. The resulting
window will not be a clear as non-coated polyester but it is acceptable in most applications.
Embossing
Embossing is a process that can greatly enhance the look of a membrane switch and improve the user experi
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ence. There are two methods for embossing. First, you can use a male and female die. This allows for a clean
finish but has height limitations. The second method is hydro-forming: it allows for greater embossing heights
but is more expensive. Typically, a material is embossed 1 to 1.5 times the thickness of the base material. It is
possible to emboss to a higher multiple, but the durability of the keypad is sacrificed.
Fiber optic backlighting does not wear out. In a typical design, two or more layers of woven fiber optic cloth
are used to for a rectangular light emitting area. The fiber optic product is typically 0.068¡± (1.7mm)thick and
anywhere from 1sq inch to over 100 sq inches. The fibers coming off one end are then bundled into a circular
ferrule and coupled to one or more LED light sources. Fiber optic panels never need replacement. Remote
light sources offer 10,000 to 100,000 hours life. Optical Fibers are not effected by extremes in humidity (0% to
100%) or temperature (-40 to +85 deg C)
Electroluminescent Lamps (EL Lamps)
EL Lamps are a good option for backlighting membrane switches. They are lower priced compared to fiber
optics and offer additional design flexibility. The color of light emitted from an EL can vary depending on the
phosphors that are used. Some common colors are blue/green and yellow/green, white, blue and orange. The
life of an EL Lamp varies based on the way it is used. EL Lamps have a half life: once they reach their half
life the brightness stars to fade rapidly. If the light is just being turned on when you hit a key on a switch the
lamp will take a very long time to reach its half life of approximately 3000-8000 hours depending upon the
quality of the phosphor being used. EL Lamps are not a good choice if the lamp is on for an extended period of
time. To help expand the life of an EL Lamp you can have it fade or flash, this could double the life of the
lamp.