The SnAg alloy plating solution of the invention is a SnAg alloy plating solution including a water-soluble tin compound, a water-soluble silver compound, and a particular sulfide compound in an amount in the range of 0.25 mol or more and 10 mol or less with respect to 1 mol of silver in the water-soluble silver compound.

The SnAg alloy plating solution of the invention is a SnAg alloy plating solution including a water-soluble tin compound, a water-soluble silver compound, and a particular sulfide compound in an amount in the range of 0.25 mol or more and 10 mol or less with respect to 1 mol of silver in the water-soluble silver compound.

Reaction products of amines and polymers containing saturated heterocyclic moieties may be used as levelers in metal electroplating baths. The reaction products may plate metal with good surface properties and good physical reliability.

Copper electroplating baths include reaction products of amines, polyacrylamides and sultones. The reaction products function as levelers and enable copper electroplating baths which have high throwing power and provide copper deposits with reduced nodules.

A method includes: agitating base members that has been immersed in an electrolytic solution inside of an electroplating tank so as to flow in a circumference direction along an inner wall of the electroplating tank; and electroplating the base members flowing along the circumference direction in the electrolytic solution inside of the electroplating tank. The flow of the base members along the circumference direction is caused by a flow of magnetic media along the circumference direction in the electrolytic solution inside of the electroplating tank or is caused by rotation of an agitation unit provided at a bottom side of the electroplating tank. At least one of the base members touches a bottom cathode, and a base member positioned upward relative to the base member touching the bottom cathode is electrically connected to the bottom cathode via at least the base member touching the bottom cathode.

A method includes: agitating base members that has been immersed in an electrolytic solution inside of an electroplating tank so as to flow in a circumference direction along an inner wall of the electroplating tank; and electroplating the base members flowing along the circumference direction in the electrolytic solution inside of the electroplating tank. The flow of the base members along the circumference direction is caused by a flow of magnetic media along the circumference direction in the electrolytic solution inside of the electroplating tank or is caused by rotation of an agitation unit provided at a bottom side of the electroplating tank. At least one of the base members touches a bottom cathode, and a base member positioned upward relative to the base member touching the bottom cathode is electrically connected to the bottom cathode via at least the base member touching the bottom cathode.

Provided is an electroplating solution of tin or a tin alloy in which the thickness variation of wafer bumps is maintained at a low level even in various changes of plating conditions and thus the mass productivity is improved. The electroplating solution of tin or a tin alloy may include tin ions as metal ions, a conductive salt, a carboxylic acid as a structure refiner, and a combination of a flavone compound and a quaternary ammonium compound as a thickness variation improving agent.

Provided is an electroplating solution of tin or a tin alloy in which the thickness variation of wafer bumps is maintained at a low level even in various changes of plating conditions and thus the mass productivity is improved. The electroplating solution of tin or a tin alloy may include tin ions as metal ions, a conductive salt, a carboxylic acid as a structure refiner, and a combination of a flavone compound and a quaternary ammonium compound as a thickness variation improving agent.

The tin alloy plating solution of the present invention includes (A) a soluble salt including at least a stannous salt, (B) a soluble salt of a metal nobler than tin, (C) an alkane sulfonic acid including 9 to 18 carbon atoms in a molecule or a salt thereof, (D) a non-ionic surfactant including one or more phenyl groups in a molecule, and (E) a leveling agent.

The tin alloy plating solution of the present invention includes (A) a soluble salt including at least a stannous salt, (B) a soluble salt of a metal nobler than tin, (C) an alkane sulfonic acid including 9 to 18 carbon atoms in a molecule or a salt thereof, (D) a non-ionic surfactant including one or more phenyl groups in a molecule, and (E) a leveling agent.