Conductive silver paste is divided into two categories: ① polymer silver conductive paste (drying or curing into a film, with organic polymer as the bonding phase); ② sintered silver conductive paste (sintering film, sintering temperature > 500 °C, glass frit or oxide as binder phase).

Conductive silver pastes are divided into two categories:

①Polymer silver conductive paste (drying or curing into film, with organic polymer as adhesive phase);

②Sintered silver conductive paste (sintered to form a film, sintering temperature > 500°C, glass frit or oxide as bonding phase). Silver powder is classified according to particle size, the average particle size < 0.1μm (100nm) is nano silver powder; 0.1μm < Dav (average particle size) 10.0μm is coarse silver powder. The three categories that make up the silver conductor paste require different types of silver powders or combinations as conductive fillers, and even different formulations in each category require different silver powders as conductive functional materials. The purpose is to use * The minimum amount of silver powder realizes the optimal utilization of silver electrical conductivity and thermal conductivity, which is related to the optimization of film performance and cost.

There are many preparation methods for powder. As far as silver is concerned, physical methods (plasma, atomization method) and chemical methods (silver nitrate thermal decomposition method, liquid phase reduction) can be used at one time. Since silver is a precious metal, it is easy to be reduced and returned to the elemental state, so the liquid-phase reduction method is the most important method for preparing silver powder at present. That is, silver salt (silver nitrate, etc.) is dissolved in water, and a chemical reducing agent (such as hydrazine hydrate, etc.) is added to deposit silver powder. After washing and drying, silver reduction powder is obtained. The selection of agents, the control of reaction conditions, and the use of surfactants can prepare silver micropowders with different physical and chemical properties (particle morphology, degree of dispersion, average particle size and particle size distribution, specific surface area, bulk density, tap density, Grain size, crystallinity, etc.), mechanical processing (ball milling, etc.) of the reduced powder can obtain polished silver powder (polished silver powder), flake silver powder (silver flake).

According to the use of silver powder in silver conductor paste. Now the silver powder used in the electronics industry is divided into seven categories:

①High sintering active silver powder for high temperature sintering silver conductive paste

②High-dispersion silver powder for high-temperature sintered silver conductive paste

③High conductivity reduced silver powder

Silver powder for electronic industry

④Bright silver powder

⑤Flake silver powder

⑥Nano silver powder

⑦Coarse silver powder

Types ①②③ are collectively referred to as silver micropowder (or reduced powder), the application of type ⑥ silver powder in silver conductor paste is under exploration, and type ⑦ coarse silver powder is mainly used in electrical aspects such as silver alloys.

Several silver pastes currently in use include:

①Low temperature silver paste for membrane switches and flexible circuit boards based on PET

②Paste for single-board ceramic capacitors

③Silver paste for varistor and thermistor

④Silver paste for piezoelectric ceramics

⑤Silver electrode paste for carbon film potentiometer

Main applications of low temperature and room temperature curing conductive silver adhesive:It has the characteristics of low curing temperature, extremely high bonding strength, stable electrical properties, and suitable for screen printing. It is suitable for conductive and thermally conductive bonding in room temperature curing welding occasions, such as quartz crystals, infrared pyroelectric detectors, piezoelectric ceramics, potentiometers, flash tubes, shielding, circuit repair, etc. It can also be used for conductive bonding in the radio instrumentation industry. ; Can also replace solder paste to achieve conductive bonding.