Acidic aqueous composition for semiglossy tin plating and member having semiglossy tin plating film

Abstract

An acidic aqueous composition for semiglossy tin electroplating has a water-soluble tin (II)-containing substance and a surfactant. The surfactant includes a surfactant (A) comprising N,N′,N′-polyoxyethylene-N-alkyl-1,3-diaminopropane. The surfactant (A) the number of carbon atoms of the alkyl group that bonds to N ranges from 14 to 18. The weight-average molecular weight of the surfactant (A) ranges from 300 to 1500.

What is claimed is: 
     
         1 . An acidic aqueous composition for semiglossy tin electroplating, comprising:
 a water-soluble tin (II)-containing substance; and   a surfactant,   wherein said surfactant comprises a surfactant (A) comprising N,N′,N′-polyoxyethylene-N-alkyl-1,3-diaminopropane.   
     
     
         2 . The acidic aqueous composition for semiglossy tin electroplating according to  claim 1 , wherein, in said surfactant (A), the number of carbon atoms of the alkyl group that bonds to N ranges from 14 to 18. 
     
     
         3 . The acidic aqueous composition for semiglossy tin electroplating according to  claim 1 , wherein the weight-average molecular weight of said surfactant (A) ranges from 300 to 1500. 
     
     
         4 . The acidic aqueous composition for semiglossy tin electroplating according to  claim 1 , wherein the content of said water-soluble tin (II)-containing substance in tin content equivalent ranges from 5 g/L to 200 g/L and the content of said surfactant (A) ranges from 0.5 g/L to 40 g/L. 
     
     
         5 . The acidic aqueous composition for semiglossy tin electroplating according to  claim 1 , which contains an organic sulfonic acid compound. 
     
     
         6 . The acidic aqueous composition for semiglossy tin electroplating according to  claim 5 , wherein the content of said organic sulfonic acid compound ranges from 50 g/L to 300 g/L in organic sulfonic acid content equivalent. 
     
     
         7 . A member, comprising:
 a member to be plated; and   a semiglossy tin plating film that is formed on at least part of the surface of said member to be plated, by electroplating of acidic aqueous composition for semiglossy tin electroplating comprising:
 a water-soluble tin (II)-containing substance; and 
 a surfactant, 
 wherein said surfactant comprises a surfactant (A) comprising N,N′,N′-polyoxyethylene-N-alkyl-1,3-diaminopropane. 
   
     
     
         8 . The member according to  claim 7 , wherein said semiglossy tin plating film in said member is electroplated under a condition of current density of 5 A/dm 2  or higher. 
     
     
         9 . The member according to  claim 7 , wherein said semiglossy tin plating film of said member has a ratio of 8 or less of glossiness Gs(60°) measured in accordance with JIS 28741: 1997 (ISO 2813: 1994) of the semiglossy tin plating film obtained in a case of electroplating under conditions of plating temperature of 45° C. and current density of 15 A/dm 2 , with respect to said glossiness Gs(60°) of the semiglossy tin plating film obtained in a case of electroplating under conditions of plating temperature of 45° C. and current density of 5 A/dm 2 . 
     
     
         10 . The member according to  claim 7 , wherein said semiglossy tin plating film in said plating member has a ratio of 1.3 or less of arithmetical mean roughness Ra measured according to JIS B0601:2001 (ISO 4287:1997) of the semiglossy tin plating film obtained in a case of electroplating under conditions of plating temperature of 45° C. and current density of 15 A/dm 2 , with respect to said arithmetical mean roughness Ra of the semiglossy tin plating film obtained in a case of electroplating under conditions of plating temperature of 45° C. and current density of 5 A/dm 2 . 
     
     
         11 . The member according to  claim 7 , wherein said semiglossy tin plating film in said plating member has a ratio of 1.3 or less of root mean square roughness Rq measured according to JIS B0601:2001 (ISO 4287:1997) of the semiglossy tin plating film obtained in a case of electroplating under conditions of plating temperature of 45° C. and current density of 15 A/dm 2 , with respect to said root mean square roughness Rq of the semiglossy tin plating film obtained in a case of electroplating under conditions of plating temperature of 45° C. and current density of 5 A/dm 2 . 
     
     
         12 . The member according to  claim 7 , wherein said semiglossy tin plating film in said member has a thickness ranging from 1 μm to 5 μm. 
     
     
         13 . The member according to  claim 7 , wherein said semiglossy tin plating film in said member is formed by electroplating with a current density ranging from 5 A/dm 2  to 15 A/dm 2 , and a ratio (before/after) of a value (unit: seconds) of zero crossing time (unit: seconds) of said member as measured in a solderability test by a balance method according to JIS C60068-2-54: 2009 (IEC60068-2-54: 2006) after an environment test of standing for 8 hours in an environment at 105° C. and relative humidity of 100%, with respect to the value (unit: seconds) measured before the environment test, is 2.1 or less. 
     
     
         14 . The member according to  claim 7 , wherein said member to be plated is an electronic component. 
     
     
         15 . The member according to  claim 14 , wherein said electronic component includes one, two or more types selected from the group consisting of resistors, variable resistors, capacitors, filters, inductors, thermistors, crystal oscillators, switches, connectors, lead wires, printed circuit boards, and semiconductor integrated circuits and modules. 
     
     
         16 . The member according to  claim 7 , wherein, in said surfactant (A), the number of carbon atoms of the alkyl group that bonds to N ranges from 14 to 18. 
     
     
         17 . The member according to  claim 7 , wherein the weight-average molecular weight of said surfactant (A) ranges from 300 to 1500. 
     
     
         18 . The member according to  claim 7 , wherein the content of said water-soluble tin (II)-containing substance in tin content equivalent ranges from 5 g/L to 200 g/L and the content of said surfactant (A) ranges from 0.5 g/L to 40 g/L. 
     
     
         19 . The member according to  claim 7 , which contains an organic sulfonic acid compound. 
     
     
         20 . The member according to  claim 19 , wherein the content of said organic sulfonic acid compound ranges from 50 g/L to 300 g/L in organic sulfonic acid content equivalent.