Method for coarsening copper crystal grains in objects to be plated and copper-plated membrane having coarsened copper crystal grains in copper-plated membrane

Abstract

A copper-plated film having enlarged crystals can be obtained with a simple operation using a method for enlarging copper crystal grains in a plated object. Such a method, may include: (a) electroplating an object to be plated in an electrolytic copper plating solution, which contains sulfuric acid, copper sulfate, chloride ions, a brightener, and a leveler, and in which the content of sulfuric acid is 200 g/L or more; and (b) subjecting the electroplated object to be plated to a heat treatment at 400° C. or lower.

1 . A method for enlarging copper crystal grains in a plated object, the method comprising:
 (a) electroplating an object to be plated in an electrolytic copper plating solution, the electrolytic copper plating solution comprising sulfuric acid in 200 g/L or more, copper sulfate, chloride ions, a brightener, and a leveler; and   (b) subjecting the electroplated object to be plated to a heat treatment at 400° C. or lower.   
     
     
         2 . The method of  claim 1 , wherein the heat treatment in the subjecting (b) is at 300° C. or higher. 
     
     
         3 . The method of  claim 1 , wherein the sulfuric acid in the electrolytic copper plating solution in the electroplating (a) is less than 500 g/L. 
     
     
         4 . A copper-plated film, comprising:
 copper crystal grains in the copper-plated film in a size of 5 μm or more, and a crystal plane is preferentially oriented along (200).   
     
     
         5 . The method of  claim 2 , wherein the sulfuric acid in the electrolytic copper plating solution in the electroplating (a) is less than 500 g/L. 
     
     
         6 . The method of  claim 1 , wherein the heat treatment in the subjecting (b) is in a range of from 300 to 400° C. 
     
     
         7 . The method of  claim 1 , wherein the heat treatment in the subjecting (b) is in a range of from 300 to 350° C. 
     
     
         8 . The method of  claim 1 , wherein the heat treatment in the subjecting (b) is for a period in a range of from 1 to 180 minutes. 
     
     
         9 . The method of  claim 1 , wherein the heat treatment in the subjecting (b) is for a period in a range of from 10 to 120 minutes. 
     
     
         10 . The method of  claim 1 , wherein the copper crystal grains reach a size of at least 5 μm. 
     
     
         11 . The method of  claim 1 , wherein the copper crystal grains reach a size in a range of from 5 to 100 μm. 
     
     
         12 . The method of  claim 1 , wherein 90% or more of the copper crystal grains are oriented along a crystal plane (200). 
     
     
         13 . The method of  claim 1 , wherein the electroplated object has a maximum stress in a range of from 5 to 15 kgf/mm 2 . 
     
     
         14 . The method of  claim 1 , wherein the electroplated object has a hardness in a range of from 30 to 70 HV. 
     
     
         15 . The method of  claim 13 , wherein the electroplated object has a hardness in a range of from 30 to 70 HV.