Common Faults and Maintenance Guide for Membrane Switches (Part 3)

Release date:

Www.zdxtt.com

2021-07-26

Thin-film switch Common Faults and Maintenance

5. The button does not conduct.

The most common issue with membrane switches is that the keys fail to conduct properly. Fortunately, membrane switch manufacturers thoroughly inspect each key's functionality before products leave the factory, ensuring that all supplied items meet 100% functional standards. However, occasionally customers report that after a few months of use, the film becomes unresponsive or requires significant force to press, even though the product still exhibits some level of functional response. What could be the underlying cause of this issue?

This phenomenon is particularly pronounced in humid environments, where moisture causes the circuit resistance to increase. As a result, connections may overheat, leading to melting and discoloration. In such cases, proper waterproofing measures are essential (the waterproof structure of the membrane switch features a serpentine sealing ring). Additionally, careful attention must be paid to ensuring tight seals at every stage of packaging.

Another scenario involves the customer's external power supply delivering an excessively high current, which directly damages the circuitry. To address this issue, it is essential to design the circuit traces as thick as possible and ensure that the silver paste applied during printing meets the specified thickness standards—additional printing steps may be required if necessary. Alternatively, the circuit can be redesigned entirely using FPC flexible printed circuit boards. Additionally, it is advisable to communicate with the customer to keep the operating current below 20 milliamperes whenever feasible. In the design of membrane switches, the power button should ideally have two dedicated lines to prevent the circuit from being subjected to sudden high-voltage and high-frequency surges when power is interrupted, thus avoiding potential damage.

Third, the design of the membrane switch is unreasonable (referring generally to membrane switches assembled with dome switches), leading to improper positioning of the dome switches during user operation and subsequently causing adverse consequences. Therefore, it is essential that the membrane switch features a rational design, ensuring precise placement of the dome switches during assembly. In cases where precision is particularly critical, the dome switches can first be affixed directly onto the underlying circuit board.

Additionally, the silver paste circuit with a 1.00 mm wire pitch is highly susceptible to being punctured by conductors within the socket.

In summary, for any issues raised by users, the Engineering Department must carefully analyze the root causes and trace them back to the original design. "Engineering design" is the key determinant of the quality of membrane switches, and highly skilled technical personnel serve as the cornerstone ensuring superior product quality. When designing membrane switches, it is essential to engage in open communication with user-side technical teams, break through conventional approaches, embrace innovative thinking, and simultaneously integrate scientific principles with practical manufacturing techniques. This holistic approach will enable the development of membrane switch designs that are both distinctive and tailored to meet the specific needs of our customers, ultimately delivering products that exceed expectations.