Advantages and disadvantages of several common types of film switches

Advantages and disadvantages of several common types of film switches

Film switch is an operating system that integrates key function, indicator element and instrument panel. It is composed of four parts: panel, upper circuit, isolation layer and lower circuit. Press the film switch, the contact of the upper circuit deforms downward, and makes contact with the plate of the lower circuit. After the finger is released, the contact of the upper circuit bounces back, the circuit is disconnected, and the circuit triggers a signal.

The film switch has the advantages of rigorous structure, beautiful appearance, good sealing, damp proof and long service life. Film switch for the use of different groups of people, environment, terminal equipment, structure and process are also different, Zhidexing and you talk about the advantages and disadvantages of several common types of film switch.

Advantages and disadvantages of several common types of film switches

1, metal shrapnel (pot piece) type: metal shrapnel as conduction medium.

Advantages: good touch, even strength, high stroke accuracy; The operation can hear the clear sound, can clearly know the operation situation, to avoid some equipment buffer time, and repeated operation; The operating temperature can reach -20 ~ 80℃

Disadvantages: When the lining board is not smooth or pasted in the bending radian is too large, the shrapnel may cause short circuit, misoperation and no rebound phenomenon.

Suggestion: Use in flat, can withstand the strength of the key lining board, or directly use thickened PCB board as the line layer.

2, hot pressing convex bud feel type: use film material to print the contact surface, rolling convex point to form a elastic force.

Advantages: High life, can reach more than 500,000 times; Feel good, stroke and strength can be customized according to customer needs;

Disadvantages: mold cost is high, need to open convex bud mold; When used in a high temperature environment, the key force may be weakened.

Suggestion: The metal mold of the convex bud mold can ensure the consistency of the key force and stroke.

3, the plane light touch type: the contact point adopts the thin film substrate printing conductive body, does not use the secondary process

Advantages: key life is high, can reach a million times; The conduction contact area is large to ensure the conduction rate.

Disadvantages: no handle feel, easy to cause repeated operation or misoperation;

Suggestion: Try to enlarge the spacing between keys, otherwise it will increase the failure rate and reduce the life.

4, capacitance induction type: the use of conductive body to induction conduction.

Advantages: can be like capacitive touch screen, in a certain distance sensing action; The sensing distance can be designed according to customer's specifications.

Disadvantages: low qualified rate of finished products, allergic to surrounding electromagnetic interference, very high design requirements; Related electronic components and chip support are required.

5. PCB circuit type: replace the thin film circuit layer with PCB circuit board

Advantages: High precision PCB line, more solid and reliable welding LED, lower resistance value; The thickened PCB line layer can be used directly as a lining board.

Disadvantages: PCB is hard material, can not be bent.