Semi-Bright Nickel Plating Bath and Method of Using Same

Abstract

A nickel plating bath for plating a semi-bright nickel deposit on a substrate comprising a) nickel sulfateions; b) a soluble salt of chloroacefic acid, acetic acid, glycolic acid, proprionic acid, benzoic acid, salicylic acid or chlorobenzoic acid; and c) at least one diol selected from the group consisting of hexyne diol, butyne diol and combinations of the foregoing. The semi-bright nickel plating bath described herein produces sulfur-free semi-bright deposits over a very wide current density range. The plating bath described herein is at least substantially free of coumarin and produces desirable leveling characteristics. The bath also requires no aldehydes to achieve simultaneous thickness and electrolytic potential (STEP) and has extremely low stress and excellent ductility.

1 . A nickel plating bath for plating a semi-bright nickel deposit on a substrate, the nickel plating bath comprising:
 a) nickel ions;   b) a soluble salt of chloroacetic acid, acetic acid, glycolic acid, proprionic acid, benzoic acid, salicylic acid or chlorobenzoic acid, and   c) at least one diol selected from the group consisting of hexyne diol, butyne diol and combinations of the foregoing,   wherein the nickel plating bath is substantially free of coumarin, substantially free of aldehydes and has a pH from 4.1 to 5.0.   
     
     
         2 . The nickel plating bath as claimed in  claim 1 , wherein the soluble salt is a sodium, potassium, lithium, magnesium or nickel salt of salicylic acid. 
     
     
         3 . The nickel plating bath as claimed in  claim 2 , wherein the soluble salt is sodium salicylate. 
     
     
         4 . The nickel plating bath as claimed in  claim 1 , wherein the concentration of the soluble salt in the nickel plating bath is between about 0.5 and about 20.0 g/l. 
     
     
         5 . The nickel plating bath as claimed in  claim 1 , wherein the plating bath also comprises an additive selected from the group consisting of ethoxylated (or propoxylated) butyne diol, ethoxylated (or propoxylated) hexyne diol, acetylenic alcohols, and ethoxylated (or propoxylated) acetylenic alcohols. 
     
     
         6 . The nickel plating bath as claimed in  claim 1 , wherein the at least one diol comprises both hexyne diol and butyne dial. 
     
     
         7 . The nickel plating bath as claimed in  claim 6 , wherein the concentration of hexyne diol in the nickel plating bath is in the range of 50 mg/L to 500 mg/L and the concentration of butyne diol is from 30 g/l to 300 mg/L. 
     
     
         8 . The nickel plating bath as claimed in  claim 7 , wherein the concentration of hexyne diol in the nickel plating bath is in the range of 100 mg/L to 200 mg/L and the concentration of butyne diol is from 60 mg/L to 120 mg/L. 
     
     
         9 . The nickel plating bath according to  claim 1 , wherein the plating bath has a pH between about 4.4 and about 4.6. 
     
     
         10 . The nickel plating bath according to  claim 1 , wherein the plating bath does not include coumarin or an aldehyde. 
     
     
         11 . A method of plating a substrate to produce a sulfur-free semi-bright nickel deposit thereon, the method comprising the steps of:
 a) providing a nickel plating bath comprising:
 i) nickel ions; 
 ii) a soluble salt of chloroacetic acid, acetic acid, glycolic acid, proprionic acid, benzoic acid, salicylic acid or chlorobenzoic acid; and 
 iii) at least one diol selected from the group consisting of hexyne diol, butyne diol and combinations of the foregoing; and 
   b) contacting the substrate with the nickel plating bath and applying electrical current to provide a semi-bright nickel deposit on the substrate,   wherein the nickel plating bath is substantially free of coumarin, substantially free of aldehydes, and has a pH from 4.1 to 5.0.   
     
     
         12 . The method according to  claim 11 , comprising the step of plating a bright nickel layer over the semi-bright nickel deposit. 
     
     
         13 . The method according to  claim 12 , wherein a simultaneous thickness and electrolytic potential (STEP) of the plated deposits is at least about 100 mv. 
     
     
         14 . The method according to  claim 13 , wherein the STEP of the plated deposits is between about 110 and about 145 mv. 
     
     
         15 . The method according to  claim 13 , wherein the STEP of the plated deposits is at least about 120 mv. 
     
     
         16 . The method according to  claim 11 , wherein the plating bath has a pH between about 4.4 and about 4.6. 
     
     
         17 . The method according to  claim 11 , wherein the plating bath does not include coumarin or an aldehyde. 
     
     
         18 . The method according to  claim 11 , wherein the stress of the deposit is less than about 15,000 psi tensile. 
     
     
         19 . The method according to  claim 18 , wherein the stress of the deposit is less than about 4,000 psi tensile. 
     
     
         20 . The method according to  claim 11 , wherein the ductility of the deposit, measured in accordance with the Chrysler ductility method, is at least about 0.4. 
     
     
         21 . The method according to  claim 20 , wherein the ductility of the deposit, measured in accordance with the Chrysler ductility method, is about 0.5. 
     
     
         22 . The method according to  claim 11 , wherein the soluble salt in the nickel plating bath is a sodium, potassium, lithium, magnesium or nickel salt of salicylic acid. 
     
     
         23 . The method according to  claim 22 , wherein the soluble salt is sodium salicylate. 
     
     
         24 . The method according to  claim 11 , wherein the concentration of the soluble salt in the nickel plating bath is between about 0.5 and about 20.0 g/L. 
     
     
         25 . The method according to  claim 11 , wherein the plating bath also comprises an additive selected from the group consisting of ethoxylated (or propoxylated) butyne diol, ethoxylated (or propoxylated) hexyne diol, acetylenic alcohols, and ethoxylated (or propoxylated) acetylenic alcohols. 
     
     
         26 . The method according to  claim 11 , wherein the at least one diol comprises both hexyne diol and butyne diol. 
     
     
         27 . The method according to  claim 26 , wherein the concentration of hexyne diol in the nickel plating bath is in the range of 50 mg/L to 500 mg/L and the concentration of butyne diol is from 30 g/l to 300 mg/L.