銅の電気めっきにおける磁場効果－スルーホールめっきへの応用－

Abstract

In a magnetic field, an electrochemical reaction generates a macroscopic solution flow called MHD flow by the Lorentz force, which enhances mass transfer in the diffusion layer (MHD effect). In electroplating, the MHD effect comes from two-dimensional (2D) nucleation in an electrical double layer accompanied by the unstable growth of non-equilibrium fluctuations (called asymmetrical fluctuations). Electroplating under a magnetic field provides the other magnetic field effect called the micro-MHD effect, which emerges with micro-MHD flow and symmetrical non-equilibrium fluctuations in a diffusion layer, and suppresses three-dimensional (3D) nucleation. That is to say, the MHD effect acts as a positive catalyst, whereas the micro-MHD effect is employed as a negative catalyst, or inhibitor. Furthermore, owing to the strong penetration of the magnetic field into the materials, micro-MHD flows are effectively induced even in the inside of a complicated minute structure. Therefore, by controlling the magnetic field, we can expect high quality plating in the through-hole plating. In this paper, along with its application to through-hole plating, copper magneto-electroplating is examined from various aspects.