With the rapid development of modern electronics industry and information industry, the electronic equipment that produces electromagnetic wave interference has increased sharply. Electromagnetic wave pollution has become one of the social hazards concerned by all countries in the world. Using conductive metal powder electroplating to develop electromagnetic shielding rubber filling materials is an important technical means to deal with this pollution.

Conductive shielding technology

Electromagnetic shielding materials are divided into surface conductive shielding materials and filled composite shielding materials. Filling composite shielding material is a new type of material introduced to the market after the surface conductive shielding material, which has a great tendency to catch up and can be developed in large quantities. As the core technology of filling composite shielding material, the research of conductive filler is also deepening.

At present, foreign countries have used this technology to develop a variety of different material combinations of electromagnetic shielding rubber products.

At present, pure silver powder is mainly used as conductive filler in China. Silver has excellent electrical conductivity and oxidation resistance, and the use of silver powder or silver coated filler as electromagnetic shielding material has significant shielding effect. However, silver is expensive, very dense, not competitive in the market, only suitable for special occasions as a shielding raw material, and the low-frequency electromagnetic shielding effect is very poor, difficult to meet the needs of broadband electromagnetic shielding. Copper has good electrical conductivity and moderate price, but the density of copper is large, and it is not easy to disperse in the polymer matrix, which affects the electromagnetic shielding effect of composite materials. In addition, copper powder is easy to be oxidized and deteriorated to reduce electrical conductivity. Nickel powder does not oxidize as easily as copper powder, but nickel has a lower electrical conductivity. In order to improve the comprehensive performance of the filler, copper or nickel silver plating is often used. Graphite, carbon black has the characteristics of low cost, good dispersion, but often in a very high content can have a certain electromagnetic shielding effect, which will lead to a significant decline in the mechanical properties of the product, and the product itself is black, affecting the color diversity of the product, the application range is limited, and is often used in the form of carbon powder nickel plating.

Generally, there are two ways of surface coating process of metal powder: electroplating and electroless plating. Northwest Rubber and Plastics Research and Design Institute concluded that electroplating is more stable, more efficient and less polluted than electroless plating through relevant research and analysis, and carried out corresponding research and development.