Conductive paste is a basic functional material that integrates materials, chemicals, and electronic technology.It is composed of two or more types of conductive phase (conductive filler), binder phase (glass powder), and organic carrier. The resulting uniform paste. The conductive paste usually does not have conductivity at room temperature, but during the sintering process, the organic carrier volatilizes and burns, and the conductive particles diffuse and connect to each other to form a conductive path and thus have conductivity. At present, with the rapid innovation and development of electronics, information, and microelectronic technology, environmental protection, precision, and miniaturization have become the development direction of electronic components, and the performance requirements of conductive pastes are becoming higher and higher. Although the prices of precious metals have risen in recent years, base metal fillers and silver-plated conductive fillers such as silver-coated copper have become one of the research hotspots. However, Ag is the longest and most widely used filler in metal-based conductive fillers.
Silver is widely used in modern industry. It has the following characteristics: optimal room temperature conductivity, optimal thermal conductivity, strongest reflection characteristics, photosensitive imaging characteristics, antibacterial and anti-inflammatory properties. In addition, silver also has relative chemical stability (the cheapest metal that does not oxidize at high temperatures). With the development of the electronics industry, silver’s electrical conductivity and thermal conductivity make it an indispensable material for the electronics industry.” In the electronics industry, silver also has its own shortcomings, which are mainly reflected in three aspects: poor resistance to solder erosion, Silver ion migration, sulfidation 18. Studies have shown that the morphology and size of the conductive phase in the conductive paste are the main factors that determine the sintering quality, rheological properties, and electrical properties of the conductive paste.
Influence of the silver morphology of the conductive filler. The filler morphology can be generally divided into fibrous, spherical, flake and mixed types. Compared with spherical micro-fillers of the same particle size range, fibrous and flake-shaped micro-fillers can provide a larger contact area and contact probability, thereby having a lower percolation threshold and promoting the formation of a better conductive network. The resistance of the slurry is mainly composed of the internal resistance of the filler, the contact resistance and the tunneling resistance, in which point contact is formed between the spherical powder filler and surface contact and line contact are formed between the flake powder filler, which has a lower contact resistance, while Due to the special two-dimensional structure of the powder, the slurry of the flake filler has excellent slurry stability, shielding effect and adhesion strength). The conductive paste was prepared using spherical and flake silver powders with similar particle sizes. The square resistance of the sintered film of the spherical powder paste was 2.318 m. sq-‘, and the square resistance of the flake powder paste was 1.671 mQ. sq. -‘. The flake silver powder with a low bulk ratio has a higher specific surface area to increase the coverage of the powder, thereby reducing the contact resistance and forming a better conductive path. Conductive adhesives were formulated with micron flakes and other morphological silver powders, and similar conclusions were drawn.
In recent years, many companies have appropriately added small-sized spherical powders and nano-sphere powders to micron flake powders to obtain better conductive properties while reducing costs. Suzhou Senhui has accumulated rich experience in the field of silver-coated copper powder conductive paste. If you need to reduce costs or encounter technical problems in making conductive paste, please contact us.