How to prevent and handle silver migration in conductive silver paste of multi-layer thin-film switches

Conductive silver pastePrepare a thin film switch. Thin film switches are composed of multiple layers of thin films, and the thin film layers composed of different materials play different roles, jointly completing the functions of thin film switches in electrical products. The circuit layer is the main functional layer of the membrane switch, which is an electronic circuit designed according to the required functions of the circuit product. Conductive silver paste is printed on PVC, PC or PET materials, and then combined with the panel layer and isolation layer to form the membrane switch. When manufacturing thin film switch circuit layers, attention should be paid to the prevention and treatment of silver migration.

Prevention and treatment of silver migration:

1) Try to widen the gap outside the silver circuit (wire) as much as possible and maintain a low voltage (potential);

2) A layer of carbon paste or blue transparent insulating ink with a thickness>30 μ m can be applied on the silver circuit;

3) To prevent silver from accelerating migration in humid environments, exhaust holes should be added around the membrane switch during design;

4) Pay attention to the hygiene conditions of the printing environment, and avoid dust and pinholes when printing insulation coatings. If dust and debris fall between wires and circuits, it may cause a decrease in electrical performance under certain conditions;

5) If the silver paste insulation layer of the screen printed circuit is insufficiently cured or has excessive solvent, it will reduce the insulation performance of the insulation layer, thereby reducing the anti migration performance of silver in humid air media.

Screen printed conductive silver pasteAfter drying, the following three-stage curing method should be used:

a. 2/3 of the time (specified temperature);

b. Leave at room temperature for 1-2 hours;

c. Infrared drying takes 1/3 of the time (at the specified temperature).

This can achieve the optimal resistance value.

Using protective insulation coating and transparent green ink, UV curing should be thorough, with a wavelength of 180-420nm and a power of 80-120W/cm. Accurate UV speed adjustment, using a wire mesh of 160-300 mesh/inch (64-120T/cm, depending on the situation).

product overview

Thin film switch conductive silver pasteIt is composed ofultrafine silver powderDeveloped with low-temperature curing thermoplastic resin, suitable for screen printing various thin film switch conductive circuits

Typical Uses

1) Membrane switch for desktop computer keyboard

2) General flexible membrane switch

3) Other types of membrane switches

advantage

Good printability, conductivity, oxidation resistance, hardness, and strong adhesion

Performance Description