The conductive aluminum paste is composed of aluminum powder, glass powder, organic binder and some additives. The particle size of the aluminum powder used is generally below 10um and is spherical. The surface of aluminum powder is often covered with a layer of aluminum oxide or aluminum nitride (due to the different cooling methods in the production of aluminum powder). The production of glass powder is now basically lead-free. The commonly used glass powder materials are SiO2, Al2O3, Bi2O3, B2O3, ZnO and so on. In addition, in order to optimize the boiling resistance, conductivity and thermal expansion coefficient of the conductive aluminum paste, alkali or alkaline earth metal oxides such as Li2O, K20, and Mg0 are often added to the glass frit.
Organic binders are usually prepared by mixing ethyl cellulose, resin, benzyl alcohol, terpineol, butyl carbiol, butyl carbiol acetate, etc. and dissolving them at a temperature of about 80°. In order to improve the thixotropy, leveling, gloss and printing appearance of screen printing, a small amount of castor oil, diffusion pump oil, rosin and other ingredients will be added to the organic binder. In addition, additional additives are added to the conductive aluminum paste slurry to reduce sintering warpage, eliminate sintering lump, and enhance boiling resistance.
As the basic material of electronic products, electronic paste has many classification methods. For example, according to the price of conductive particles, it is divided into precious metal conductive paste and base metal conductive paste, such as silver paste, palladium paste and ruthenium series paste are precious metal pastes and aluminum paste, copper paste, zinc paste and nickel paste are base metals Paste; according to different uses can be divided into conductive paste, resistance paste and dielectric paste.
Conductive aluminum paste is an important kind of electronic paste. Currently, it is widely used as a material for the back electric field of crystalline silicon solar cells. The technology is relatively mature. The conductive aluminum paste has basically been localized.