Behind the flourishing development of many industries such as electronics and new energy, there is a seemingly insignificant but crucial material - conductive silver paste. Keyboards, mobile phones, tablets, solar panels, smart cards, RFID and other devices rely on them to achieve connections and fully function.

Silver has the highest conductivity among metals, with excellent conductivity, thermal conductivity, good chemical stability, and weldability, and is widely used in various fields of modern electronics industry. Whether it is an OLED flexible screen or an LCD screen, there are countless thin conductive lines inside the screen, which are printed with "conductive silver paste".

1. Composition of conductive silver paste

Conductive silver paste is usually a viscous paste prepared by mechanical mixing of micrometer sized metal silver particles, polymer binders, solvents, additives, etc.

Among them, silver powder is a conductive functional phase, and its intrinsic characteristics such as microstructure, morphology, size and distribution, surface activity, etc. have a significant impact on the conductivity of the final film layer.
Adhesive phase is the film-forming substance of conductive paste, which can be divided into two categories: inorganic adhesive phase and organic adhesive phase. Its main functions are twofold: firstly, it acts as a skeleton, bonding silver powder together to achieve the conductive function of wiring; The second is to act between the film layer and the substrate to achieve the bonding between the conductive film layer and the substrate.
Solvent is also an essential component of conductive paste, playing a role in dissolving resin and adjusting the viscosity of the paste.
In addition, additives also play an important role in conductive pastes, mainly including thixotropes, dispersants, leveling agents, antioxidants, etc., which improve the coating performance of the paste and the physicochemical properties of the film layer.

2. Conductive silver paste classified by curing method

Conductive silver paste can be divided into three categories based on the curing method: sintered conductive silver paste, low-temperature cured conductive silver paste, and UV cured silver paste.

A. Sintered conductive silver paste
Sintered conductive paste is made by mixing silver powder as the conductive phase, glass powder as the bonding phase, organic solvents and other additives as the organic carrier. This type of conductive silver paste is sintered into a film at a sintering temperature generally>500 ℃.
Sintered conductive silver paste is mainly used for high-temperature insulation substrates such as ceramics and glass. This type of conductive silver paste is commonly used in electronic components such as potentiometers and thick film circuits that can withstand high temperatures, such as MLCC internal electrodes, photovoltaic cell electrode printing, and PCB local conductive paths.

B. Low temperature curing conductive silver paste
Low temperature cured conductive silver paste is composed of silver powder, polymer organic system, organic solvent, and additives. The curing temperature is generally less than 300 ℃, and good adhesion of circuit wires to the substrate can be obtained using screen printing technology.
The main characteristics of low-temperature curing conductive silver paste are low curing temperature, high bonding strength, and stable electrical performance. It is suitable for conductive and thermally conductive bonding in low-temperature curing welding applications, such as quartz crystals, infrared pyroelectric detectors, piezoelectric ceramics, potentiometers, flash lamps, as well as shielding, circuit repairs, etc; It can also be used for conductive bonding in the wireless instrument industry.
Low temperature cured conductive silver paste can also be used for printing on various flexible substrates, such as PET, PC, PEN, PI, paper, thermoplastic elastomers, etc.

C.UV cured silver paste
The bonding in UV cured silver paste is more complex compared to the previous two, and should at least have UV curing monomers, photosensitizers, and crosslinking agents.
Its curing mechanism is also relatively complex. The photosensitizer is excited by ultraviolet light to become an activating molecule, which induces the copolymerization reaction of photosensitive polymers and ultimately crosslinks to form a network structure.
Due to the fact that film formation does not require heating, UV cured silver paste is often used as a thermal sensor for bonding and conducting components that do not require heating and curing.

Conductive silver paste, as one of the indispensable basic materials in the electronics industry, its performance optimization and technological innovation will directly affect the progress and development of the entire industry. With the continuous updating and progress of applications, we look forward to the wider application of conductive silver paste in the future.

SAT NANO is one of the best supplier of silver powder in China, we can offer nano particle and micron particle for client to do condutivity paste, if you have any enquiry, please feel free to contact us admin@satnano.com