Keypad Technical Details

Specialist keypad technical guidance.

Custom design and engineering of geometry and physical characteristics creates keypads that fit your application
at a low cost per key.

A host of design-in technical features are available enabling you to get exactly the right combination that will improve user engagement and enhance both the aesthetic and the function of your product – often with little or no additional cost.

How Interface Controls can work with you to get your keypad technical specifications right:

The special circumstances in which many devices are operated in demand specific design requirements.
This is when silicone rubber keypads really come into their own.

You can submit your design data files to us in a range of CAD formats, including: DWG DXF IGES STEP and SolidWorks.

See below for further information outlining basic technical guidance to take into account when designing silicone rubber keypads –
also referred to as silicone buttons or elastomeric keypads.

Scroll and expand to view.

Silicone Rubber Keypads Dimension Detail


1 – Typical outside radius 1.0mm to 1.5mm

2 – Minimum radius 0.3mm

3 – Minimum inside radius 0.2mm

4 – Minimum spacing between edges of rubber dome and guide hole 1.0mm

5 – Guide holes minimum 1.0mm diameter

6 – Width of rubber button base typically 2.0mm greater than ‘a’

7 – Minimum radius for the side of the keytop 0.25mm

8 – Minimum radius for the top edges of the keytop 0.2mm

Key Height

H = Dimensions from keytop to front panel

S = Key stroke

H-S > 1.5mm

Silicone Rubber Keypads Dimensions: key height

Key Corner Radius

R = Corner radius of cut-out

r = Corner radius of rubber

1.0mm < R < 1.25mm

0.75mm < r < 1.0mm

Silicone Rubber Keypads Dimensions: key corner radius

Key Clearance

A & B = Dimensions of front panel cut-out

a & b = Dimensions of rubber

A-a > 0.4mm

B-b = 0.3mm

 Silicone Rubber Keypads Dimensions: key clearance
Silicone Rubber Keypads Mechanical Detail

PCB Location

Pull through interference fit ‘a’

Push through hollow to aid insulation ‘b’

Silicone Rubber Keypad Mechanical: PCB location

Silicone Rubber Keypad Hardness

Base typically 55% shore

Keytops up to 90% shore

Silicone Rubber Keypad Mechanical: keypad/key top hardness

Control of Keystroke

Mechanical stops for controlling keystroke when using plastic keytops

Silicone Rubber Keypad Mechanical: control of keystroke

Anti-rocking Device

P = Diameter of post

P = 1.0mm

t = Height difference between post and conductive pill

t = 0.1#0.15mm

Silicone Rubber Keypad Mechanical: anti-rocking device
Silicone Rubber Keypads Illumination Options

Keytop Illumination

Translucent rubber

Selective carbon printing or array contact pills

Keypad Illumination: keytop

Light Guide Illumination

LED window in keytop

Translucent rubber insert light guide

Keypad Illumination: light guide

Status Indication

Construction showing LED indicator

Keypad illumination: status indication
Silicone Rubber Keypad Electrical Detailing

Conductive Carbon Pills

Sizes available, 0.2mm to 10.0mm dia. in 0.5mm increments

Conductive pill resistance: less than 150 ohms with 100 gram loading

Life expectancy: 30 millon operations

Gold-plated nickel options

Silicone Rubber Keypad Mechanical: keypad/key top hardness

Selective Carbon Printing

Size and layout customised to key shape

Conductive printing resistance: less than 800 ohms with 300 gram loading

Life expectancy: 1 million operations

Silver ink options

Maximum Contact Pill Size

Silicone Rubber Keypads electrical: Contact pill size

d = D-1.5~2.0mm


Recommended PCB Electrode Patterns

Layout available as AutoCAD dwg file (contact office for further details)

Suggested PCB coating – gold, selective carbon

Silicone Rubber Keypads electrical: PCB electrode patterns



Design Sample Keypad for Evaluation

FREE Desktop Design Sample

Our handy desktop design sample is great to use when looking at options for your

silicone rubber keypads.

Fill out the request form and we’ll send one to you without obligation and free of charge.