ＥＤＴＡ浴による高速度無電解銅めっきの延性に及ぼす添加剤の影響

Abstract

Effects of various additives on the high-speed electroless copper deposition from EDTA bath were investigated. By electron-microscopic observation of the surface of copper deposit from the additive free EDTA bath, it was shown that the surface consisted of fine and easily fallen off particles that would cause spontaneous decomposition of the bath when they fell off into the solution. Single use of ferrocyanide, potassium nickel cyanide, or sodium nitroprusside as additive in EDTA bath improved the ductility of the copper deposits to some extent, and the deposits from these baths provided the surface consisting of small pyramidal crystals at 50°C, which grew to larger and more leveled grains at 70°C. As previously reported, the authors found that the ductility of copper deposit was remarkably improved when 2, 2'-dipyridyl and the other compound, e.g. potassium nickel cyanide, were added together into the EDTA bath. Electron-micrographs of copper deposits from these baths contaning two additives provided the surfaces apparently more leveled than those from the baths containing each additive individually. Thus the corelation between ductility and surface leveling was confirmed. Ductility of copper deposit and deposition rate increased with increasing bath temperature up to 80°C, beyond the temperature deposition rate decreased because of the predominance of Cannizzaro reaction. Further addition of some kinds of nonion type surface active agents into the plating bath was found to give favorable effects on the ductility of the deposit.