Conductive filler is an important part of the conductive adhesive, which improves the conductive performance. There are three commonly used types: non-metal, metal and metal oxide.
Non-metallic fillers mainly refer to carbon family materials, including nano graphite, nano-carbon black, and nano carbon tubes. The advantages of graphite conductive adhesive are stable performance, low price, low relative density and good dispersion performance. Silver-plated nano graphite can also be prepared by silver plating on the surface of nano graphite to further improve its comprehensive performance. Carbon nanotubes are a new type of conductive material that can obtain good mechanical and electrical properties, but in practical applications, there are still many problems to be solved.
Metal filler is one of the most used fillers in conductive adhesives, mainly powders of conductive metals such as silver, copper, and nickel. Silver powders is a filler that is used more in conductive adhesives. It has the lowest resistivity and is difficult to be oxidized. Even if oxidized, the resistivity of the oxidation product is also very low. The disadvantage is that silver will produce electronic transitions under DC electric field and moisture conditions. Because copper powder is easily oxidized, it is difficult to stably exist, and it is easy to aggregate and agglomerate, resulting in indispensable dispersion in the conductive adhesive system. Therefore, copper powder conductive adhesive is generally used in occasions where the conductivity is not high.
The advantages of silver-plated copper powder/Ag coated Cu particle are: good oxidation resistance, good conductivity, low resistivity, good dispersion and high stability; it not only overcomes the defect of easy oxidation of copper powder, but also solves the problem Ag powder is expensive and easy to migrate. It is a highly conductive material with great development prospects. It is an ideal conductive powder that replaces silver and copper and has a high cost-performance.
Silver coated copper powder can be widely used in conductive adhesives, conductive coatings, polymer pastes, and various fields of microelectronics technology that need to conduct electricity and static electricity, and non-conductive materials surface metallization. It is a new type of conductive composite powder. It is widely used in the fields of electrical conductivity and electromagnetic shielding in various industries such as electronics, electromechanics, communications, printing, aerospace, and military industries. For example, computers, mobile phones, integrated circuits, various electrical appliances, electronic medical equipment, electronic instruments, etc., so that products are not interfered by electromagnetic waves, while reducing the harm caused by electromagnetic radiation to the human body, as well as the conductivity of colloids, circuit boards, and other insulators, making the insulating object have good electrical conductivity.
Relatively speaking, the conductive properties of metal oxides are not good enough, and they are rarely used in conductive adhesives, and there are few reports in this regard.