With the rapid development of modern electronics industry and information industry, the number of electronic devices that produce electromagnetic wave interference has increased dramatically. Electromagnetic wave pollution has become one of the social hazards concerned by countries all over the world. The use of 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. Filled composite shielding materials are new materials that have been introduced to the market after surface conductive shielding materials. And as the core technology of filled composite shielding materials-conductive filler research is also in-depth.

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

At present, pure silver powder is mainly used as conductive filler in China. Silver has excellent electrical conductivity and resistance to oxidation, and the use of silver powder or silver-plated fillers as electromagnetic shielding materials has a significant shielding effect. However, silver is expensive, dense, and has no market competitiveness. It is only suitable as a shielding material for special occasions, and it has a poor electromagnetic shielding effect on low frequencies, making it difficult to meet the needs of broadband electromagnetic shielding. Copper has good conductivity and moderate price, but the density of copper is large and it is not easy to disperse in the polymer matrix, thus affecting the electromagnetic shielding effect of the composite material. Moreover, copper powder is easily oxidized and deteriorated to reduce conductivity. Nickel powder is not as easy to oxidize as copper powder, but the conductivity of nickel is low. In order to improve the overall performance of the filler, copper silver plating or nickel silver plating is often used. Graphite and carbon black have the characteristics of low cost and good dispersion, but they often have a certain electromagnetic shielding effect at a high content, which will cause the mechanical properties of the product to decrease significantly, and the product itself is black, which affects the product ’s The variety of colors and the range of applications are limited, and they are often used in the form of carbon nickel plating.

In general, there are two methods for the surface coating process of metal powder: electroplating and chemical plating. The Northwest Rubber and Plastics Research and Design Institute has concluded that electroplating is more stable, more efficient, and less polluting than electroless plating through relevant investigations and analysis. research and develop.