In Mold Film (IMF) Keypad Materials

Materials used in IMF keypads vary to meet customer’s requirements. We use Polycarbonate (PC) & Thermoplastic Polyurethane (TPU) materials. Each material has properties or characteristics that make it more suitable for certain conditions.

PC material is used when tall key heights (up to 5.0mm) are required. PC has properties which make it an excellent choice for IMF keypads. Some of these properties are:

• Molds easily in the vacuum forming process.
• Resistant to many chemicals.
• Many pre-textured surfaces available.
• Holds up well under fluorescent lighting.
• Application of graphics and reproduction of color is excellent.
• Typical thickness of material used for keypads is 0.125mm.

TPU material is used when tall key heights are not necessary. TPU is not available in pre-textured surfaces; however the tooling can be fabricated to add texture to the surface of the material. Tensile strength is excellent and adds to the reliability and durability of the product. It is resistant to hydrocarbons, chemicals, ozone, bacteria and fungus.

TPU has properties which make it excellent for IMF keypads. These properties include:

• High abrasion resistance.
• UV resistance without yellowing or becoming brittle.

Both PC and TPU are available as glossy keypads. However, smudges and scratches, such as finger nail marks, show up more readily on glossy surfaces. For this reason a satin finish is recommended.

Graphic Inks for IMF Keypads:

Graphic inks are specifically formulated for use with each material. As these inks are screened on the subsurface of the keypad material, they must bond not only with the keypad material, but also to the material used to back fill the vacuum formed keypad. These inks must have the ability to stretch with the forming process and stand up to the rigors of back filling with polycarbonate or co-molding with silicone rubber. (Co-molding is the process of molding under heat and pressure to fuse two materials together.)

Thin Profile IMF Specifications to consider:
The radii at the corners/edges of these keytops must not be less than 0.3mm. If less than 0.3mm, the inner radii of the foil would be less than 0.15mm and this will cause light leakage and sink marks to appear on the surface of the keys.

Present key height, including the printed film, should not be less than 0.55mm for plastic injection back fill.

The distance between keys is critical in the forming of these IMF keypads. The K value in the following formula should be 2.8 or less for ideal manufacturing and performance.

K = H1 + H2 + L2 / L1
L1 – Top distance between neighboring keys.
L2 – Base distance between neighboring keys.
H1 – Total height of 1st key.
H2 – Total height of 2nd key.

The length and width of individual keys should not be less than 3.2mm in consideration of graphics on the key. The line width of the graphics should not be less than 0.18mm.

In Mold (IMF) Keypad Artwork

Graphics can be applied to the top surface or the subsurface of the keypad. By printing on the subsurface of the IMF film, the graphics are sandwiched in between the film and the plunger providing the ultimate protection.

The artwork is first screen-printed to a thin plastic film. By applying the graphic ink to the subsurface, the graphics are encapsulated within the keypad to better protect from abrasion and chemical wear over the lifetime of the product. After the artwork cures, the film is then embossed (via a high-pressure forming machine) to achieve the keypad shape.  High-precision registration pins ensure the graphics on the keypad are aligned accurately and consistently during each forming process.  After the film is embossed, the plungers for each key are injected. The injected plungers can be permanently bonded to either a plastic or rubber keypad base. 

The last process step is for the keypad to be punched to meet peripheral dimensions.  In a secondary operation, IMF keypads can be modified for a custom die-cut profile to meet your design specification.

Materials used in IMF keypads vary as needed to meet our customer’s requirements. We use Polycarbonate (PC) and Thermoplastic Polyurethane (TPU) materials. Each material has properties or characteristics that make it more suitable for certain conditions.

Vacuum Metalizing ( VM ) Keypad Materials

Vacuum Metalizing (VM), also known as Thermal Evaporation or Physical Vapor Deposition, is another means that Top Bound USA offers to obtain the metalized look that is so desired in today’s handheld devices. The products produced in this manner will be Nickel free, thus making them more environmentally friendly. Metals used in the VM process are typically aluminum and chrome.

The VM process applies a thin, uniform metalized coating to the surface of films and plastics used in the manufacture of our keypad products.  A primer is sprayed on the surface of the material prior to the VM process. After the VM process, a hard coat is applied which makes the surface more chemical and abrasion resistant.  This process is excellent for coverage on flat and vertical surfaces.

Metals are heated to the point of evaporation which allows them to migrate to the colder surface of the film or plastic being coated. This process is performed in a vacuum so the vaporized metal does not oxidize in the oxygen in the air.
We can also supply the keypads manufactured by the “sputter” method. This method yields slightly thicker layers of metal and is therefore more abrasion resistant. However, a hard coat is still applied to the surface. 

Non-conductive vacuum metallization ( NCVM) may be provided  if there is a requirement. For example: The need to pass RF through coated material.

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Light Guide Film ( LGF )

Light Guide Film (LGF) is another option that Top Bound USA can offer to back light keypads and other products. This is the thinnest product for backlighting keypads currently available. These films are thin (0.125mm), flexible, and light weight. These films can be bent but not creased.

LGF has light scattering ability. This allows for uniformity and brightness. Hot spots are not an issue with this material. LGF typically is designed for side view LEDs, but top view LEDs may be used in some situations. The use of LGF can reduce the number of LEDs in a unit, thus reducing the cost of materials and also reducing the power drain on the unit.

Sheet Metal Keypads ( SMK )

Sheet Metal Keypads (SMK) are widely used in today’s thin hand held devices. These keypads offer some of the thinnest keypads on the market and yet are extremely strong. The graphics are chemically etched into the material which relieves the concern of graphic abrasion.

Typically, metal keypads will have silicone co-molded to the back side. This silicone can be reverse printed to provide color for graphics or for decoration. TPU plus silicone can also be used for further decoration.

Glass Keytops ( GKT )

Glass, as a keytop material  is one of the latest developments in decoration and graphic protection. It provides exceptional clarity with its polished surfaces. Both flat and 3D (multi-faceted diamond cut) surfaces are available. The glass is hardened both by baking and chemical processes so it is very strong. The second surface printing of graphics or decoration assures that they will never wear off. These keytops can be adhered to both silicone and TPU materials, and since we can make the keytops with a minimum thickness of 0.5mm, they will work for ultra thin keypads. Cut outs are even available so secondary decoration can be added to enhance the look.

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Ultra Thin Polycarbonate ( PC ) / Acrylic  Keytops

(Ultra-Thin Hard Top Keypads)

The minimum thickness of PC keytops is 0.5mm in consideration of the limitation in injection molding. The side wall should have a minimum thickness of 0.35mm excluding the radius on the corner on the keytop. This dimension is to assure the de-gating is not seen from the top view of the button. The radius at the edges of the keytops is recommended to be a minimum of 0.1mm. If a “step” is going to be molded into the keytop the minimum step height should be 0.3mm. The gating of the tooling must have a minimum of 0.2mm.

These low profile keytops are second surface printed to prevent graphic abrasion. However when dark colors are printed on PC material, scratches on the surface of the material itself will begin to show with use. Hard coating is possible to increase the surface hardness. If scratching is a major concern acrylic material should be considered. If acrylic material is used the minimum thickness will increase from 0.5mm to 0.8mm. Acrylic has lower heat resistance than PC.

In keeping with the ultra thin concept, Top Bound USA can supply metal dome or polycarbonate dome assemblies to give excellent reliability and tactile feel simulating that of mechanical switches

Silicone Rubber Compression Molded Keypads / Mobile Phones

Silicone Rubber Keys

Draft angle should be 1.0º minimum (2.0º to 3.0º preferred for ease of removal from the tool)- Typical Durometer is 60-70 Shore A, (although a custom Durometer may be blended for your  application)   Minimum interior base radii between keys to be 0.3mm to prevent tearing of web.

Minimum exterior edge radii to be 0.2 – 0.3mm.- Clearance between individual keys and housing to be 0.1mm minimum.  Spacing between keys to be 1.8mm minimum.

Typical actuation force to be between 150-180g depending on domes and keypad Durometer.

Typical curvature of the key face should not vary by more than 0.5mm to ensure a best quality  printing/etching process. Printing should not be closer than 0.3mm to the edge of the key top radius.

Hard Caps

Standard plastic injection molding tolerances apply.

Draft angle should be 1.0º minimum (2.0º preferred for ease of ejection from the tool, or if surfaces are textured).

Spacing between keys within key clusters to be 0.1 – 0.2mm minimum.

For clear keycaps, the bottom surface should be flat to allow for screen printing.

Screen printing border to be 0.10mm minimum from edge of screen printed keys.

Keys may be press fit onto the silicone base (with a constraining flange) or attached with adhesives.

A number of textures and cosmetic options are available including laser etched chrome.

Keypad Base  ( Thickness )

 Typical base thickness to be 0.5 – 1.2mm (0.8 to 1.0mm is preferred).

 Minimum wall thickness between features is 0.5mm, and 0.3mm at perimeter of keypad.

 0.3mm thick sections allowed above LED’s and required recesses.

Actuation Plungers / PCB Interface

Typical plunger to have flat base with a recommended diameter of 2.0mm (plunger diameter may  increase depending on dome size).

 A generous draft (30º) will improve key stability.

 Plunger should touch domes line to line at nominal condition.

Base-web

The base-web surrounding the keys should be 0.2mm to 0.3mm to prevent tearing and  maximize tactile feel of the domes.

Air Channels

 Air channels are required under the keypad base to prevent suction when the keys are actuated (typical air channel are 2.0mm wide by 0.3mm deep).

Polished Surfaces / Backlighting

 To increase light transmission of the LEDs, the rear surface of the keypad and LED recesses  may be high-polished within the tool to improve or balance backlighting.

Dimensional Tolerances for Silicone Keypads

Dimension (mm)          Tolerance (+/-)
     0.0 - 10.0                      0.10 mm
   10.1 - 20.0                      0.15 mm
   20.1 - 30.0                      0.20 mm
   30.1 - 40.0                      0.25 mm
   40.1 - 50.0                      0.30 mm
   50.1 - 100.0                    0.35 mm
 100.1 and up                    0.5%

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Metal Dome Design Guide

Metal domes, also known as snap domes come in a variety of shapes and sizes, and are as the name implies, dome-shaped disks of metal designed to “snap” when pressure is applied to the top of the dome. The design is such that when the pressure upon the dome is released, the dome snaps back into its original shape. The tactile feel of the snap makes the metal dome ideal as a switch contact for applications with limited space.

Design considerations include dome size, material composition, thickness, and mating circuit design which determine the characteristics of tactile feel, actuation force, actuation travel and contact resistance. Top Bound can supply over 50 different sizes and variations of metal domes, and has extensive experience in metal dome array applications to assist in optimizing designs for every requirement.

The dome material is generally stainless steel, although variations such as copper alloy are available in selected diameters. Most versions are supplied with silver plating.

Keypad Tactile Feel

Tactile feel is the clicking sensation caused by the sudden collapsing of the rubber dome’s flexible wall. The degree of snap is typically a function between actuation force and travel. The only way to measure and describe the tactile feel is through a snap ratio. Snap ratio is the tactile variance between the actuation force required to collapse the dome walls of the rubber switch and the force needed to hold the switch contact to an electrode pad. (The term "snap" refers to a physical action, not an audible sound.)

Keypads with snap ratios of 40 – 60% have excellent tactile feel and relatively long life, while keypads with snap ratios below 40% have relatively weak tactile feel, yet longer life which can be determined from the above formula. Snap Ratio depends upon the variance between Actuation Force (F1) and the Contact Force (F2).  This value will directly influence Tactile Feel, which is caused by force variation.  That is, when the force drops from F1 to F2, the operator can feel a force change at their fingertip immediately.  This instant force variation is the Tactile Feel. 

Keypad Printing

Keypads can have paint/ink applied to the entire keypad or just to specific areas only. Negative, positive, and a combination of negative and positive printing are available and depicted below.

Positive printing has ink/paint applied to the keytop with the key material as the background for the graphics (for example, a red seven on a gray rubber key as the background).  Negative printing has ink printed on the keytop allowing the material color of the rubber key to be exposed in the shape of the graphic specified.  Another example of negative printing can be a gray rubber key with red ink covering the entire keytop and a black color seven in the middle of the key.  Laser Etched keypads and key graphics with several colors can have both positive and negative printing.  Any number or color of layers can be printed.  Please note: If too many layers of printed graphics are applied to the keytop, then the surface may have tiny steps that appear as lines.

Silk Screen Printing / Pad Printing

The printed graphics for each key are applied via silk screen printing or pad printing.  Both printing techniques have their own strengths and weaknesses.  In general silk screen printing is used for rubber surfaces and pad (tempo) printing is used for plastic surfaces.  Both printing processes utilize silicone-based ink.  The silicone in the ink serves two purposes; (1) aides in the bond between the ink and the rubber surface and (2) the silicone will give the graphics the flexibility to flex with a rubber surface.  Both purposes will aide in increasing the longevity of the graphics. Graphic colors are applied individually.  Each color represents an additional step in the manufacturing process.  After one color of the printed graphics is applied, the keypad will enter an oven to cure the silicone ink.  This curing stage will permanently bond the  silicone ink to the keypad surface.  To ensure that the correct color graphics are being applied, please supply Top Bound with a Pantone number and/or a color chip of the color needed.

Pad printing is similar to a typical hand held stamp.  The rubber stamp/pad has a tip formed in the shape of the graphic.  The process involves automated equipment dipping the tip of the pad into a container of ink and then pressing the ink tip to the surface of the part.  Due to the elastic tip, pad printing is great for parts with non-flat surfaces.  Pad printing has shorter cycle times than silk screen printing, but the life of the graphics is shorter.

Silk Screen Printing Limitations

Silk screen printing, while more expensive than pad printing, can result in higher quality graphics.  The silk screen acts as a mask on the keypad by allowing ink to pass through open paths in the specific areas in the screen to the surface of the keypad. The open paths allow ink deposits to sit on the surface of the key in the shape of the required graphic.  This printing process has the precision to apply graphics with uniform thickness throughout the layer of the graphic with sharp edge boundary lines.  Silk screen printing limitations are depicted below.

A  On negative printing applications,  maximum curvature on convex keytops is 0.5 mm.

B  On negative printing applications, maximum curvature for concave keytops is 0.5 mm.

C Blind bump/dimple: any size possible.  Only positive printed graphics and spray color can be applied on the key surface.  Min. distance between graphics and locating dimple is 0.5mm

D  On negative printing applications, the typical minimum distance from the edge of key to the edge of printed graphics is 0.35–0.45 mm (contour keytops can vary).

Surface Coatings

Several coatings are available for aesthetic purposes and for improving the durability of the keypad and its graphics.  Each surface coating provides its own advantage for different applications. 

The following surface coatings are available for most applications:

Silicone Keypad Coating

The most commonly used surface coating is a silicone coating. This coating is one of the most economical methods for extending graphic life.  A single coat (15 µmm ± 3 µmm thick) can easily double or triple the life of silk-screened graphics.  A second coat can be applied if necessary.  Two or more coatings can cost about the same as Polyurethane, therefore Polyurethane may prove to be a better choice if more protection is needed. This coating is avilable in a glossy or matte finish.

(PU) Polyurethane Keypad Protective Coating

PU Protective Coating can increase the abrasion resistance of printed graphics up to 15+ times. This spray coating can be applied to either the entire topside of the keypad or to the keytops only. It will maintain a uniform thickness on both vertical and horizontal surfaces. PU has been abrasion resistance tested successfully for up to the equivalent of 1,000,000+ cycles. In addition to increasing abrasion resistance, PU also prevents oil, moisture, and other harsh environmental fluids from penetrating through the keypad surface. After the coating is applied, the surface will feel harder and the “rubbery” standard keypad feel is virtually eliminated. PU has the following characteristics:

• Surface oil resistance of 60h/23° C  ASTM 3 expansion <2%
• Wide operating temperatures: -40° C to 85° C
• Polyurethane thickness:  15.0 ± .5 μmm
• UV Resistant

Please Note:  Results were gathered utilizing an abrasion tester.  This tester will drag an abrasive tape across the printed graphics to measure the wear resistance of the printed ink deposits.  Failure is determined when any portion of the graphics is worn off.  The life is measured by the length of tape dragged across the key until failure occurs.   The life of the graphics will vary depending on the coating thickness and shape of keytop.  Double and triple coatings can be applied to reach a longer life; however this will cause an increase in price.  Consult with our engineering staff if you have additional questions. 

Keypad Backlighting

Keypads are backlit in many creative ways. LED’s are most frequently used to achieve backlighting because of their low operating temperature and small size. Diffused backlighting is achieved by using translucent silicone rubber and a light pipe/plate or by using the base material of the keypad itself as a light pipe. This allows light to escape from the side of the key as well as from the top surface creating a halo effect on negative printed keypads.

Another backlighting source is the electroluminescent lamp (EL lamp), which is increasing in popularity. An EL lamp is an illuminative panel that provides a uniform backlight for the keypad.  This panel is adhered to the bottom of the keypad and supplied as an assembly.  EL lamps are a cost effective means of providing high brightness backlighting in a low profile package, offering reliable light output across a keypad or display. Lamps with curvilinear forms or with holes, cutouts, and notches can be made, although there are limits on minimum feature size.  Please note that necessary EL lamp drivers are not supplied.

Light Guide Film (LGF) may be selected as it is the thinnest backlighting material currently available. The film captures and redistributes light from light sources, typically LEDs, to evenly backlight keypads without hotspots.

There are several different backlighting sources available.  Once you have selected one, your next step is to design the keypad to have maximum light emissions in the areas needed.  Laser etching is one way to allow light to penetrate the keypad’s printed graphics.

In order for a keypad to be laser etched, the keypad needs to be sprayed and printed in a specific way. Each keypad that is laser etched is molded with translucent rubber.  Then, the keypad is sprayed with a white layer of paint on the entire topside of the keypad.  Next, the printed graphic colors are applied to the keytops.  Finally, the entire topside of the keypad is sprayed with the desired color needed for the application (generally black since black absorbs and blocks any light form penetrating through).  The keypad looks like one color, yet several color layers are covered.  A laser then etch/ peel layers off until the desire color layer is exposed.  When selecting colors for light to penetrate through, keep in mind that the lighter colors will absorb less light and therefore allow more light to pass through.  Keypads with backlighting will be molded with a tool that has been polished to give the keypad a nice smooth and clean surface.  This will in turn maximize light emissions.

To help solve the problem of light hot spots a translucent material is sometimes screened with reflective white ink on the backside (base).  If conductive ink is used as a contact, white ink can be screened between the black conductive ink and the keypad translucent material to reduce dark spots seen during backlighting.  This process can also be used if conductive pills are used, but it will add considerable cost to the overall keypad.

Conductive Keypad Contacts

Several types of contacts are available for keypads. Each contact has it’s own unique electrical characteristics.

Conductive pills are the most popular contact types for rubber keypads. The conductive pills (usually preferred) have low contact resistance with a long life. The typical life of each pill will exceed 10 million actuations, and the contact resistance is typically less than 200 ohms. Circular shape pills are generally used due to their low cost and are easily molded to the keys. Square, oval and other desired shapes are available but are not generally used with keypads due to higher production costs. Special conductive contact shapes are possible at a lower cost using conductive ink technology. Round or “Donut” conductive pills are available in limited sizes.

Available Pill Dimensions  (Round)
1.5mm             5.5mm
2.0mm             6.0mm
2.5mm             6.5mm
3.0mm             7.0mm
3.5mm             7.5mm
4.0mm             8.0mm
4.5mm             9.0mm
5.0mm           10.0mm

Screen printing with conductive ink is the preferred technology for applications which require non-circular shaped contacts.  Conductive ink has the dimensional versatility to achieve any shape or size needed.  In comparison with carbon pills, conductive ink has higher contact resistance unless multiple layers are applied to increase the thickness.

Gold plated pills are available for low contact resistance and long life applications.  They are available in circular shapes of 3 and 4 mm diameters

Circuit Board Plating

When selecting plating material for printed circuit boards, several options should be carefully considered if they are to be used in conjunction with rubber keypad conductive pills.

• Gold offers the lowest contact resistance for any keypad application. However this material is more expensive than the other available options.
• Nickel offers almost identical contact resistance characteristics as the gold (both are rated at 100 ohms). Nickel plating is generally used on circuit boards for keypad applications due to its lower costs and higher reliability in severe environmental conditions.
• Silk Screened Carbon boards should only be utilized when contact resistance in the 500-1000 ohm range can be tolerated. Silk-screened boards offer a reliable contact.
• Unmasked tin solder boards are not recommended for use with conductive rubber switches. Using this plating type may result in higher product failures due to severe oxidation.

Printed Circuit Board Pads

Shown below are examples of popular circuit board pad designs used with keypad conductive pills.  Generally, the  shorter paths on the pad will offer a better contact reliability.

Pads should be equal in size or slightly larger than the conductive pill. If larger, the pad size should be 1.25 times the pill size.  In most cases, pad contact fingers should have a minimum distance of .010” and a maximum distance of .015” between the fingers.  The minimum size of the pad traces should be .010”.

Nontoxic, silicone, conductive rubber keypads are compression molded utilizing custom-made tooling.  Both prototype and production tools are made of precise, high carbon steel and maintained by the manufacturer over the life of the tool.  Tool life may vary depending on keypad design and molding circumstances.

*   Based on gold or nickel-plated printed circuit board

** Fahrenheit to Centigrade conversion:   
°F – 32
1.8   

Life:
LED = Around 50,000 hours
ELP = 3,000-5,000 hours to half brightness
Fiber Optics = 100,000 (depending on type of bulb used as the light source.)

LEDs:
Pros = Low cost, long life, not affected by vibration (solid state), low operating voltage, and good control over brightness. They are brighter than ELP and since they operate at low voltage they don’t need an inverter as an ELP does. They are available in several colors and in several mounting configurations (SMT, right angle, reverse mount, etc.).

Cons – Even though they operate at low voltage, they require more power than some other methods.

ELP:
Pros = Uses colored phosphors, not heat to generate light. Very thin, light weight, solid state, low power consumption, and provides even light. Available in several colors also.

Cons = ELPs require an inverter to generate the needed 100 VAC @ 400 Hz, shorter life than LEDs, and inconsistent brightness.

Fiber Optic Mesh:
Pros = They provide extremely uniform backlight, no need for an inverter, and long life depending on the type of bulb used. With LEDs or halogen (which generate high heat) up to 100K hours. The bulbs used to provide the source light are easily replaced because they are not actually attached to the mesh in most cases.

Cons = They are costly!

Incandescent Bulbs:
Pros = They are low cost and very bright.

Cons = Brightness is not uniform and they generate a lot of heat, use a lot of power, and have a short life. They are affected by shock and vibration (which can break the hot filament).

Keypads can be back lighted by several different methods. The most commonly used method is by the use of LEDs. LEDs are available in several colors, brightness levels, package styles, mounting method and viewing angles. LEDs are preferred for their low cost, long life, solid state (not affected by vibration), good control over brightness level, brighter than EL panels, and no inverter needed because they operate on low voltage and draw very low current. Below you will find several suggested methods of backlighting using LEDs which can help reduce the quantity of LEDs required and direct the light in the areas that require illumination.

 If you are planning to use SMT LEDs on a flex circuit (FPC), Top Bound can supply the keypad already assembled to the FPC so you have a complete part ready to drop into your unit and connect to the FPC.

A relatively new technology for backlighting keypads is by Top Bound’s Light Guide Film (LGF). This method of flood lighting an entire keypad can utilize fewer LEDs which will conserve power drain on portable devices. The LGF is flexible and can be curved or bent, but not creased, to follow the geometry of the unit in which it is placed. Again, this film can come already adhered to the keypad so that fewer steps are required to assemble your final unit.

Both of the methods noted above can have a metal dome array assembled so that low profile keypads can have a very nice tactile feel. In the case of the FPC type, there will be cutouts for the SMT LEDs to shin through to successfully backlight the keypad. In the case of the LGF, the metal dome array will be placed underneath the LGF, with a protective layer that can be peeled away for placing the keypad assembly directly onto a PCB.  

FLOOD LIGHTING OF SEVERAL KEYTOPS WITH ONE LED can be accomplished by placing a very wide viewing angle SMD LED at the intersection of four key tops. Below you will find the viewing angle and dimensional drawing of a typical wide viewing angle SMD LED that illuminates four key tops.

ILLUMINATION OF A SINGLE KEYTOP WITH A NARROW VIEWING ANGLE LED may be accomplished by placing the LED directly under the keytop in a cavity that is surrounded by four conductive contacts, or in the middle of a donut shaped conductive contact. Below you will find a picture of a keytop that is directly illuminated from a narrow angle LED, the viewing angle of the narrow viewing LED and the dimensional drawing of the LED.

VERY THIN RUBBER KEYPADS MAY HAVE SEVERAL KEYTOPS ILLUMINATED WITH A SINGLE LED by the use of an ultra thin LEDs with a very wide viewing angle. Below you will see an example of an ultra thin (height of 0.4mm).

KEYPADS MAY BE ILLUMINATED FROM THE SIDE OF THE KEYPAD with the use of right angle SMD LEDs. Below you will see the wide viewing angle and dimensions of a typical right angle SMD LED.

LEDs MAY BE MOUNTED ON THE REVERSE SIDE OF A PCB FROM THE KEYPAD with the use of reverse mount SMD LEDs and a hole in the board. Below you will find the viewing angle and dimensional drawing of a typical reverse mount LED.

NOTE: 

This Keypad Backlighting information has been furnished for the convenience of our engineering customers. 
For specific keypad backlighting information please contact our authorized representative: 
                                       Mr. Tom McGuire at   630-428-5662 or tomm@esareps.com

For further information please call Top Bound USA
1 888 772-7042 / 1 817 642-8824
info@topboundusa.com