The Current Status of Low Temperature Curing Conductive Silver Paste

Low temperature curing conductive silver pasteThe low-temperature cured conductive silver paste is generally made by mechanically stirring and dispersing conductive silver powder, organic polymer binder phase, organic solvent, and other additives through a high-speed disperser, and then mixing and rolling them fine through a three roll grinder. The paste like suspension system is generally made by mechanically stirring and dispersing conductive silver powder, organic polymer binder phase, organic solvent, and other additives through a high-speed disperser, and then mixing and rolling them fine through a three roll grinder.Screen printing silver pasteThe production and processing technology, as well as the product performance of the slurry, are closely related to the selection, content ratio, and mechanism of action of each component. After screen printing, leveling, and low-temperature curing (generally below 200 ℃), a conductive film layer with a thickness of several micrometers to tens of micrometers can be formed on the substrate. The substrate used is generally a flexible polymer substrate that is not resistant to high temperatures and is relatively inexpensive, such as polyester (℃), which can form a conductive film layer with a thickness of several micrometers to tens of micrometers on the substrate. The substrate used is generally a flexible polymer substrate that is not resistant to high temperatures and is relatively inexpensive, such as polyester (PET) film.

1、 Composition of low-temperature cured conductive silver paste

Conductive silver powderAs the conductive phase of the slurry, its morphology, size, and particle size distribution all affect the conductivity of the conductive film layer; The organic polymer bonding phase serves as the matrix skeleton of the conductive film layer, ensuring stable suspension and bonding of the conductive silver powder while achieving adhesion and bonding between the conductive film layer and the substrate; Organic solvents are mainly used for the dissolution of resins and the dispersion of slurry filler powder particles. Solvents can not only adjust the viscosity of the slurry, but their volatility is crucial for the formation of conductive film layers. The selection of solvents should follow good compatibility with the resin. Organic carriers made by resin dissolution and dispersion will affect the printing performance of the slurry, and also have an impact on the resolution (line width, line spacing), curing process, and conductivity of the film layer after screen printing.

Additives are mainly used to improve the printing effect, better curing process, and better dispersibility of the slurry. Common additives include leveling agents, thixotropes, curing agents, adhesion promoters, etc. The addition of additives can bring certain adverse factors to the conductivity of the slurry. Therefore, the addition of additives should be comprehensively considered and their proportion should be strictly controlled.

2、 The Current Status and Shortcomings of Low Temperature Curing Conductive Silver Paste

Domestic manufacturers of silver powder paste have insufficient investment in technology research and development, limitations in production process equipment design, and significant differences in performance indicators and parameters between domestically produced conductive silver powder and similar products from international brands, such as the control of silver powder morphology and size. The quality of domestically produced organic resins varies greatly, mainly manifested in the lack of reliable detection methods for process control, especially in the preparation of organic carriers. The solubility, degree of dissolution, and proportion of organic resins in solvents often rely on the rich experience of R&D engineers or production operators for blending.

Impact on high-quality domestic productsLow temperature curing conductive silver pasteThe key factors are mainly as follows: 1) Domestic pulp research and development engineers mostly focus on screening auxiliary materials such as silver powder, resin, solvents, and additives for pulp research and development, accumulating experience in resin dissolution process, mixing and rolling process, and there is little theoretical mechanism research as technical support; 2) The R&D innovation and upgrading progress of domestic silver paste production equipment are very slow, and the key links such as impurity removal, defoaming, and fineness control of the paste are not strictly controlled; 3) The characterization of silver paste is mainly limited to the performance analysis of the conductive film layer after screen printing, leveling, and curing, and the detection of the paste itself only has two indicators: fineness and viscosity. The indicators such as the solubility of organic resin and the rheological properties of the paste are almost blank.