Design Guide - Short Version - N&H Technology

Silicone Rubber Keypad

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N&H Technology GmbH

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Design Guide - Short Version

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Technical Types

Keypads with Contact Pills Multi Moulding Colours Translucent material for Night Design with positive and negative printing

Laser Engraving on rubber keys for Night Design

Laser Engraving on plastic caps for Night Design

Keypads with Polydome and Metaldome

Silver painted or Chrome plated surface

Keytop with Epoxy Coating IMD film technique

P+R technique Rubber with plastic keys Rubber and plastic keys with integrated Light Guide

Integrated EL and LED Backlight Metall keys with backlighted legends

Singel Keys

Technical Types

N&H Technology GmbH +49 (0)2154 - 8125-0 [email protected]

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Design Rules

Terminology

Dimensions

A-a ³ 0.4 mmB-b ³ 0.4 mma-d ³ 1.5 mmc-a » 2.0 mmH ³ s + 0.4 mmp-s ³ 0.15 mmR > re » 0.8 - 1.2 mmf ³ g / 2I ³ 1.2 mmk ³ 1.5 mmm ³ 0.6 mmn ³ 1.0 mmr ³ 0.4 mm (R)t ³ 0.3 mm (R)

a ³ 1.0 mm (R)b ³ 0.5 mm (R)c ³ 2.0 mmd ³ 1.2 mme ³ 1.5 mm (Ø)f ³ 2.0 mmg » 1.0 mm wide; 0.3 mm deeph ³ 2.0 mmi ³ 1.5 mm

In applications where the keypad is completely sealed, Guide Holes are not allowed and air venting can beachieved through venting paths between keys, i.e. the air vents should not lead to outer edge of keypad.


Force [cN]

Travel [mm]S1 S2 S4

F1

F4

F2

F3

F1: Actuation forceF2: Contact force ( mechanical contact )F3: Return forceF4: Over stroke force ( electrical contact )S1: Peak travelS2: Contact strokeS4: Over stroke

Push curve

Return curve

Snap Ratio = F1-F2 x 100% F1

Force-Travel Diagram

The force drop from F1 to F2 yields Tactile Feeling. The higher the Snap Ratio, the stronger the Tactile Feeling. On the other hand, a higher Snap Ratio means a lower Return Force F3 which could cause Key Jamming.In the case of Polydomes or Metaldomes, the Tactile Feeling is concise and strong although the Snap Ratio is nominal low, because the force drop is rapid and the curve of the force drop is steep.

Key Shapes and Characteristics

Design Rules

4N&H Technology GmbH +49 (0)2154 - 8125-0 [email protected]

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Design Rules

Legends and Night Design

Positive Printing Negative Printing

Printed legend

Material colour

Printed keytop

Legend with material colour

Margin of keytop edge

Margin 0.5 + 0.15mm min.

Legend off-centre: + 0.3 mmLine width: > 0.2 mm

Through application of transmissive material the keytop and the key flank can be backlighted.

The legend, the margin of the keytop edge and the key flank are illuminated by use of transmissive material.

Laser Engraving Legends

The surface paint of legend area is evaporated by applying a laser beam. The basic paint, which makes up the legendcolour, is a light transmissive layer, whereas the surface paint is impermeable to light. If the basic paint is omitted, the keymaterial colour forms the legend colour.

In order to eliminate the dark colour of the Carbon Contact, which is visible through translucent silicone rubber, thecontact area can be pre-printed white before Carbon Dip Printing, or optionally Carbon Pills printed white on one side canbe used.

Illumination Options

Centre LED Illumination

EL Backlight

Side LED Mounting

Light Guide Integration

Translucent silicone rubber

Basic Paint for legend

Surface paint


Basic paint for legend

Transparent plastic cap

Surface paint


LED



PCB

Electroluminescent lamp (EL)

Light impermeable

Light pipe

LED

Bezel

LED


Electrical Contact

Design Shape

Circular Circular Ring Semi-Circular Ring Oval Square Square Ring Semi-Square Ring

Contact Type

Contact Surface of PCB: Gold Carbon GoldType Contact Shape Contact Resistance Max. Rating Life Cycles

Carbon Dip Printing no limit 150 - 300 Ω < 600 Ω 30 VDC / 3 mA 1-3 MioCarbon Pill circular < 100 Ω < 200 Ω 30 VDC / 5 mA > 5 MioLow Resistance Carbon Pill circular < 10 Ω < 30 Ω 30 VDC / 5 mA > 5 MioPolydome circular 1 - 10 Ω < 30 Ω 42 VDC / 20 mA > 1 MioMetal Powder Pill circular 10 - 50 Ω < 100 Ω 30 VDC / 30 mA 1 - 5 MioMetal Pill circular 1 - 5 Ω < 20 Ω 100 VDC / 100 mA > 5 MioMetaldome circular, square, oval 1 - 5 Ω < 30 Ω 42 VDC / 30 mA > 1 Mio

Standard Size of Carbon Pill

Carbon pills are usually circular from Ø 2.5 mm to Ø 8.0 mm with step 0.5 mm. Other diameters and shapes are possiblewith more costs involved.

PCB Contact Surface Options

PCB Contact Surface Material Contact Surface

Rigid FR4, CEM1, etc. Gold, Nickel, Carbon

Flexible Polyimide Gold, Nickel

Flexible Polyester Carbon, Silver, Carbon-Silver-Mixture

For high reliability applications Gold plated PCB is preferred. Silkscreen printed carbon is the most commonly used platingbecause of low cost and high chemical resistance.

PCB Circuit Type

The PCB Contact Area in each direction should be 0.5 mm min. larger than the Contact Area of keypad.For Rocker Key and Keys with Metaldomes, please send PCB Contact Circuit to N&H for approval.

Gold Traces Carbon Traces

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Design Rules


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Design Rules

Technical Options of Keypads

Silicone Rubber with Polydome Silicone Rubber with Metaldome

Silicone rubber

Foil

Metaldome

Silicone rubber

Embossed Polyester dome

Silicone Rubber with Snap-on Plastic Caps

Silicone Rubber withfree floating Plastic Caps

Plastic cap Plastic cap

Silicone rubber Silicone rubber

Bezel

P+R Technique Plastic Cap with Light Guide

Necessary preloading of the keytop throughplastic cap: 0.1-0.2 mm

Plastic top, glued or injected

Legend layer possible

Silicone rubber

Plastic cap with Light Guide

PC Light Guide double shot or sequence shot

Silicone rubber

Silicone Rubber with Snap-on Plastic Caps

Silicone Rubber withfree floating Plastic Caps

Foil transparent

Legend colour

Key colour(negative legend printing on the back of foil)

Silicone rubber

Polydome or metaldome

PCB

Legend colour

Key colour(negative legend printing on the back of foil)

PC pin

Polydome or metaldome

PCB


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Design Guide - Short Version - N&H Technology