Nano-silver is the main component of conductive ink, its concentration is a very critical issue, because it relates to the ability to achieve good conductivity and whether the smooth printing. If the concentration of silver-containing ink is large, the use of this material for fine inkjet, its high concentration and low viscosity conditions with rapid precipitation trend. In the case of high concentrations and very small particles, the distance between the particles and the particles becomes very small, which makes it difficult to prevent the occurrence of agglomeration. The same weight of particles to form a diameter of 10nm suspended matter than the number of 1μm diameter of the formation of suspended solids to more than 1 million times. Therefore, at higher concentrations, the dispersion and stabilization of nano-silver particles is a key technology to make inkjet conductive ink become a mature product.
The adjustment of the diameter of the silver particles, the surface modification method and the ink formulation can improve the dispersion stability of the silver particles. The nano-silver particles may also be dispersed in ethanol so that it is compatible with diethylene glycol or with the ethylene glycol system to form an alcohol-based dispersion.
In general, silver particles less than 100 nm are called nanosized silver. When the diameter of the silver particles reaches this scale, increasing the relative proportions of the surface atoms with higher energy will cause a sudden change in the properties of the material. This change can be expressed as a change in sintering capacity characteristics or due to a change in the band gap Caused by changes in the electromagnetic properties caused by the electrical properties or optical properties of the huge changes in the screen, such as color and transparency changes. For nano-silver, the critical point of its performance change is related to the diameter of the particles. When the particle diameter is less than 50nm, the sintering performance at low temperature (less than 200 ℃) is obviously enhanced, and the melting point can be reduced to 120 ~ 200 ℃ The Inkjet conductive ink is the use of nano-silver particles low melting point of the characteristics of the development history, which can be plastic substrates, and even paper on the basis of printing and sintering process, excellent performance of the conductive layer. Inkjet conductive inks are mostly made of spherical nano silver.
Due to the presence of tiny particles, the inkjet ink is somewhat similar to the pigment type inkjet ink. Therefore, the solid particles in the ink must meet certain requirements: the maximum diameter of the silver particles should be less than 1/10 of the diameter of the nozzle to avoid bridging and blocking phenomena, taking into account the nozzle shape and the number of operations and other factors Founder, this ratio should actually smaller. At present, many companies inkjet conductive ink silver particle diameter is generally 20 ~ 50nm. This scale of silver particles, both with low melting characteristics, but also to meet the inkjet print on the size of the requirements of solid particles.
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