Copper-tin alloy plating bath

Abstract

An object of this invention is to provide a copper-tin alloy plating bath that allows for film thickening without using cyanide ions, and that can also be applied to barrel plating. This invention relates to a copper-tin alloy plating bath comprising an aqueous solution containing a water-soluble copper compound, a water-soluble divalent tin compound, a sulfur-containing compound represented by formula (1): R—(CH 2 ) l —S—(CH 2 ) m —S—(CH 2 ) n —R  (1), wherein R is H, OH, or SO 3 Na, and l, m, and n are each independently an integer of 0 to 3, and a hydroxyl group-containing aromatic compound.

1 . A copper-tin alloy plating bath comprising an aqueous solution containing a water-soluble copper compound, a water-soluble divalent tin compound, a sulfur-containing compound represented by formula (1):
   R—(CH 2 ) l —S—(CH 2 ) m —S—(CH 2 ) n —R  (1),
   wherein R is H, OH, or SO 3 Na, and l, m, and n are each independently an integer of 0 to 3, and a hydroxyl group-containing aromatic compound.   
     
     
         2 . The copper-tin alloy plating bath according to  claim 1 , wherein the water-soluble copper compound is present in an amount such that the amount of copper ions is 1 to 60 g/L, the water-soluble divalent tin compound is present in an amount such that the amount of divalent tin ions is 5 to 40 g/L, the sulfur-containing compound is present in an amount of 5 to 500 g/L, and the hydroxyl group-containing aromatic compound is present in an amount of 1 to 50 g/L. 
     
     
         3 . The copper-tin alloy plating bath according to  claim 1 , wherein the sulfur-containing compound is at least one member selected from the group consisting of methanedithiol, 1,2-ethanedithiol, 1,3-propanedithiol, 3,6-dithia-1,8-octanediol, and bis-(sodium sulfopropyl)-disulfide. 
     
     
         4 . The copper-tin alloy plating bath according to  claim 1 , wherein the hydroxyl group-containing aromatic compound is at least one member selected from the group consisting of phenol, catechol, hydroquinone, resorcinol, pyrogallol, p-cresolsulfonic acid, sodium ascorbate, and sodium erythorbate. 
     
     
         5 . The copper-tin alloy plating bath according to  claim 1 , wherein the aqueous solution further contains a nonionic surfactant, and an aromatic ketone or an aromatic aldehyde. 
     
     
         6 . A method for copper-tin alloy plating, the method comprising performing electrolysis using an object to be plated as a cathode in the copper-tin alloy plating bath according to  claim 1 . 
     
     
         7 . An article comprising a copper-tin alloy plating film formed by the method according to  claim 6 . 
     
     
         8 . The copper-tin alloy plating bath according to  claim 2 , wherein the sulfur-containing compound is at least one member selected from the group consisting of methanedithiol, 1,2-ethanedithiol, 1,3-propanedithiol, 3,6-dithia-1,8-octanediol, and bis-(sodium sulfopropyl)-disulfide. 
     
     
         9 . The copper-tin alloy plating bath according to  claim 2 , wherein the hydroxyl group-containing aromatic compound is at least one member selected from the group consisting of phenol, catechol, hydroquinone, resorcinol, pyrogallol, p-cresolsulfonic acid, sodium ascorbate, and sodium erythorbate. 
     
     
         10 . The copper-tin alloy plating bath according to  claim 3 , wherein the hydroxyl group-containing aromatic compound is at least one member selected from the group consisting of phenol, catechol, hydroquinone, resorcinol, pyrogallol p-cresolsulfonic acid, sodium ascorbate, and sodium erythorbate. 
     
     
         11 . The copper-tin alloy plating bath according to  claim 2 , wherein the aqueous solution further contains a nonionic surfactant, and an aromatic ketone or an aromatic aldehyde. 
     
     
         12 . The copper-tin alloy plating bath according to  claim 3 , wherein the aqueous solution further contains a nonionic surfactant, and an aromatic ketone or an aromatic aldehyde. 
     
     
         13 . The copper-tin alloy plating bath according to  claim 4 , wherein the aqueous solution further contains a nonionic surfactant, and an aromatic ketone or an aromatic aldehyde. 
     
     
         14 . A method for copper-tin alloy plating, the method comprising performing electrolysis using an object to be plated as a cathode in the copper-tin alloy plating bath according to  claim 2 . 
     
     
         15 . A method for copper-tin alloy plating, the method comprising performing electrolysis using an object to be plated as a cathode in the copper-tin alloy plating bath according to  claim 3 . 
     
     
         16 . A method for copper-tin alloy plating, the method comprising performing electrolysis using an object to be plated as a cathode in the copper-tin alloy plating bath according to  claim 4 . 
     
     
         17 . A method for copper-tin alloy plating, the method comprising performing electrolysis using an object to be plated as a cathode in the copper-tin alloy plating bath according to  claim 5 .