Effect of nickel electro plated carbon fiber on electromagnetic interference shielding

Studies on shielding methods that can be a solution to electromagnetic interference that can cause problems on electronic systems and devices have gained momentum with the development of technology. Electromagnetic shielding; It can be defined as the reflection or absorption of the emitted electromagnetic wave by placing the shielding material between the source and the receiver. Shielding materials are generally metals due to their conductivity, but due to their weight and cost, new generation materials are being studied. Especially in recent years, carbon fiber materials have a wide range of uses due to their mechanical and electrical advantages. Defense industry, automotive industry, aviation and space are among the sectors where carbon fiber is used. Metallic coatings can be made in order to increase the conductivity of carbon fibers. In this study, shielding properties and microstructure images of PAN-based carbon fiber fabrics were investigated in a total of different 3 frequency ranges, 300-1500 MHz, 2170-3300 MHz, 3300-4900 MHz, by applying Ni electroplating at different current densities and durations and Ni electroless plating. It has been observed that the Ni coating increases the EMI shielding efficiency in 3 different frequency ranges. While the sample with Ni electroplating for a current density of 8,7 A/dm2 and 30 minutes showed the best shielding efficiency in the frequency ranges of 300-1500 MHz and 3300-4900 MHz, the carbon fiber sample that was coated with Ni with electroless coating method in the frequency range of 2170-3300 MHz showed the best shielding efficiency. While uncoated carbon fiber had an average of 18 dB shielding efficiency at 300-1500 MHz frequency, the shielding efficiency was 54 dB of Ni electroplated carbon fiber at 8,7 A/dm2 and 30 minutes. In the frequency range of 2170-3300 MHz, electroless Ni plating increased the shielding efficiency by 32 dB. In the frequency range of 3300-4900 MHz, carbon fiber sample with 8,7 A/dm2 current density and 30 minutes Ni electroplating showed the best shielding efficiency, Ni coating increased the shielding efficiency by 36 dB. Absorption and reflection values were calculated in order to understand the mechanism involved in the EMI shielding behavior. It has been determined that the absorption mechanism is dominant in the EMI shielding behavior.