Design Guide 1

DESIGN GUIDE: SILICONE RUBBER KEYPADS & CONDUCTIVE RUBBER KEYPADS

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Button Travel

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Note: For good tactile feel a travel of1.2 mm and a force of 135 grams is recommended.

Typical Effects

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Above effects are estimated according to typical key structures.

Rubber Keypad – General Specification

Travel 0.8 – 1.5 mm
Force 60 – 300 grams
Tactile Response Yes
Life Cycles 1,000,000
Operating Temperature -40° to + 150°C
Storage Temperature -50° to + 170°C
Dielectric Strength >1 min @ 500 VRMS
ESD Breakdown 20KV/MM
Contact Bounce <5MS
Contact Resistance <200 Ohms

Physical Properties of Silicone Rubber

Typical Physical Property Carbon Conductor Silicone Insulator
Specific Gravity@ 72°C 1.18 1.17
Durometer Hardness (Shore A) 65 ± 5 30-80 ± 5
Tensile Strength (KG/CM) >50 >70
Elongation (%) >100 >250
Tear Strength (KG/CM >9 >12
Linear Shrinkage (%) 3 – 5 3 – 4.5
Volume Resistivity (Ohm/CM) <5 1×1015

Dimensional Tolerances

Dimension Tolerances
Inches MM Inches MM
0 – .987 0 – 25 .005 .13
.998 – 1.460 25.1 – 37 .008 .20
1.461 – 1.971 37.1 – 50 .010 .25
1.972 – 2.444 50. – 1-62 .012 .31
2.445 – 2.956 62.1 – 75 .015 .38
2.957 – 3.428 75.1 – 87 .017 44
3.429 – 3.940 87.1 – 100 .020 .50
3.491 – 5.908 100.1 – 150 .024 .62
5.909 – OVER 150.1 – OVER 0.5% 0.5%