Improving corrosion resistance of Kovar by subjection to a coupled electromagnetic treatment

As a common electronic packaging device, Kovar primarily serves to secure, seal, and protect semiconductor chips. The Ni–Au coating applied to its surface effectively resists external corrosion. However, residual stress and defects generated during the electroplating process of the Ni–Au layer often diminish the corrosion resistance of the coating. This study employs a coupled electromagnetic treatment (CEMT) to regulate the Ni–Au coating after electroplating, with the aim of improving their corrosion resistance. The results indicate that the corrosion resistance of the Ni–Au coating was effectively improved after CEMT, and the product qualification rate is 95 %. The residual tensile stress was greatly reduced, the residual tensile stress in the X direction was reduced by 44.84 %, and in the Y direction was reduced by 61.75 %. The nanohardness increased from 0.74 GPa to 0.91 GPa, an increase of 22.97 %. Microstructure analysis showed that the dislocation density of the coating after CEMT was reduced by about 4.2 %, and the dislocation distribution was more uniform. The reduction of stress and the repair of defects provide an important basis for improving the corrosion resistance of the coating.