LEAD-FREE TIN ALLY ELCTROPLATING METHOD AND PLATING BATH FOR SUPPRESSING DISSOLUTION CURRENT OF ANODE USED IN THE METHOD

摘要

PPROBLEM TO BE SOLVED: To smoothly prevent the substitution deposition for noble metals in a tin (alloy) anode during electrodeposition in electroplating of the alloy of tin and metals (silver, bismuth, copper, etc.) nobler than the tin. PSOLUTION: The tin alloy elctroplating method comprises adding at least one dissolution current suppressing agent selected from the group consisting of glutamic acid-N, N-diacetic acid, methyl glycine-N, N-diacetic acid, aspartic acid and their salts to the tin electroplating bath to suppress the dissolution current of the anode and to attain the prevention of the substitution deposition of the noble metals to the anode during the electrodeposition. The dissolution current is suppressed by the addition of the suppressing agent and therefore, even if the anode current density is made lower than heretofore, the potential of the anode is shifted nobler than the natural electrode potential of the noble metal and thereby the substitution deposition to the anode of the nobler metal can be effectively prevented. PCOPYRIGHT: (C)2007,JPO&INPIT