Application of Low Temperature Curing Conductive Silver Paste in Thin Film Switches

Low temperature cured conductive silver paste is a composite material carefully formulated, mainly composed of metal silver powder, polymer resin bonding phase, solvent, and various additives mixed under appropriate mechanical force. Its excellent conductivity is mainly due to the free electron carriers provided by the added silver powder. The process of conductivity is actually the result of the interweaving and joint action of multiple mechanisms such as seepage, tunneling effect, and field emission principle.

In addition to silver powder, resin bonding phase is also an important factor affecting the performance of low-temperature conductive silver paste. Among the many polymer resins that can be used as bonding phases for different silver pastes, such as polyacid resin, epoxy resin, acrylic resin, polyacrylic acid, etc., they each have unique properties. The resin bonding phase, as a carrier of silver powder, not only determines the flexibility, hardness, and adhesion of conductive silver paste, but also affects its comprehensive performance such as bending resistance.

In practical applications, epoxy resin has limitations due to its high brittleness and relatively poor impact resistance. Polyurethane resin, on the other hand, has become an ideal choice due to its excellent bonding strength with various materials and the ability to achieve a balance between hardness and flexibility by adjusting the proportion and structure of soft and hard segments in the molecular chain through molecular design. Especially under high-frequency bending conditions, the performance of polyurethane resin is particularly outstanding.

In this experiment, we used self-made ultrafine silver powder as the conductive phase and systematically studied the effects of silver powder morphology, particle size, polymer resin type, and curing conditions on the properties of silver paste. Through careful blending and optimization, we have successfully prepared low-temperature cured conductive silver paste with low resistivity, excellent bending resistance, hardness, and adhesion. This achievement not only reflects our deep understanding and exquisite technology in materials science, but also brings new possibilities for the application of conductive silver paste.