| abstract |
A cyan electrolytic gold plating bath for forming a gold bump having a film hardness of 70 to 120 HV is provided. SOLUTION: Gold cyanide salt as a gold source is 0.1 to 15 g / L in gold concentration, 2.5 to 50 g / L in which oxalate is oxalic acid, and 5 to 100 g / L in inorganic acid conductive salt. Then, a cyan electrolytic gold plating bath for bump formation is prepared by containing 0.1 to 50 g / L of the water-soluble polysaccharide and 1 to 100 mg / L of the crystal adjusting agent at a metal concentration. As the water-soluble polysaccharide, dextrin, α-cyclodextrin, β-cyclodextrin, and dextran are preferable. [Selection] Figure 1 |