Key Points for Designing and Making Silicone Keys

1、 Functional requirements shall be paid attention to in the structural design of silicone keys:

1. Press the key to achieve the set function;

2. After removing the external force, the key can automatically reset completely;

3. The keys have a good feel when pressed and reset;

4. It also works when pressing the edge position of the key;

5. It can meet the design life requirements.

2、 Technical requirements for silicone key drawings:

1、 Silicone rubber hardness: SHA 55°±5°；

2、 Actuation force: 180±30gf;

3、 Returu force: less than 50gf;

4、 Key stroke:1.2±0.1;

5、 Thickness of carbon pill=0.5;

6、 Life cyele: 3X10E5。

3、 Other key points in silicone key design:

1. Common methods for conducting contact points:

a. Silk screen conductive ink (film thickness 10-20um)

Advantages: low cost;

Disadvantages: The resistance value is large and easy to fall off.

b. Conductive black particles, using vacuum disk adsorption method:

Advantages: good adhesion

Disadvantages: The size and form of black carbon particle are limited.

2. Carbon point specification:

Diameter general specification: Φ two Φ two point five Φ three Φ three point five Φ four Φ four point five Φ five Φ six Φ seven Φ eight

The thickness is generally 0.5~0.6 (too thin leads to high resistance)

3. Keypad sharp corner design of silicone keys:

The sharp corner of the keypad should have an arc transition, generally R=1.0mm;

4. Key design:

The large key is too long and can be designed as two or more contact points;

5. The key height should not be too high

6. Key shape design:

The structure grades from good to bad are round Key, oval Key and square Key;

7. Spacing between keys:

The minimum distance between keys cannot be less than 1.5mm.