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 sulfate ions; b) a soluble salt of chloroacetic acid, acetic acid, glycol acid or proprionic acid; and d) 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. It does not contain coumarin but produces desirable leveling characteristics. The bath 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 halide substituted (i) acetic acid, (ii) proprionic acid or (iii) salts of any of the foregoing; and   c) at least one diol selected from the group consisting of hexyne diol, butyne diol and combinations of the foregoing.   
     
     
         2 . The nickel plating bath as claimed in  claim 1 , wherein the soluble salt is a sodium, potassium, lithium, magnesium or nickel salt of chloroacetic acid. 
     
     
         3 . The nickel plating bath as claimed in  claim 2 , wherein the soluble salt is sodium mono chloroacetate. 
     
     
         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 4 , wherein the concentration of the soluble salt in the nickel plating bath is between about 2.0 to about 4.0 g/l. 
     
     
         6 . The nickel plating bath as claimed in  claim 1 , wherein the at least one diol comprises both hexyne diol and butyne diol. 
     
     
         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 of at least 4.0. 
     
     
         10 . The nickel plating bath according to  claim 9 , wherein the plating bath has a pH between about 4.4 and about 4.6. 
     
     
         11 . The nickel plating bath according to  claim 1 , wherein the plating bath does not include coumarin or an aldehyde. 
     
     
         12 . 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 halide substituted (i) acetic acid, (ii) proprionic acid, or (iii) salts of any of the foregoing; 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.   
     
     
         13 . The method according to  claim 12 , comprising the step of plating a bright nickel layer over the semi-bright nickel deposit. 
     
     
         14 . The method according to  claim 13 , wherein a simultaneous thickness and electrolytic potential (STEP) of the plated deposits is at least about 100 mv. 
     
     
         15 . The method according to  claim 14 , wherein the STEP of the plated deposits is between about 110 and about 145 mv. 
     
     
         16 . The method according to  claim 14 , wherein the STEP of the plated deposits is at least about 120 mv. 
     
     
         17 . The method according to  claim 12 , wherein the plating bath has a pH of at least 4.0. 
     
     
         18 . The method according to  claim 17 , wherein the plating bath has a pH between about 4.4 and about 4.6. 
     
     
         19 . The method according to  claim 12 , wherein the plating bath does not include coumarin or an aldehyde. 
     
     
         20 . The method according to  claim 12 , wherein the stress of the deposit is less than about 15,000 psi tensile. 
     
     
         21 . The method according to  claim 20 , wherein the stress of the deposit is less than about 2,000 psi tensile. 
     
     
         22 . The method according to  claim 12 , wherein the ductility of the deposit, measured in accordance with the Chrysler ductility method, is at least 0.4. 
     
     
         23 . The method according to  claim 22 , wherein the ductility of the deposit, measured in accordance with the Chrysler ductility method is about 0.5. 
     
     
         24 . The method according to  claim 12 , wherein the soluble salt in the nickel plating bath is a sodium, potassium, lithium, magnesium or nickel salt of chloroacetic acid. 
     
     
         25 . The method according to  claim 24 , wherein the soluble salt is sodium mono chloroacetate. 
     
     
         26 . The method according to  claim 12 , wherein the concentration of the soluble salt in the nickel plating bath is between about 0.5 and about 20.0 g/L. 
     
     
         27 . The method according to  claim 26 , wherein the concentration of the soluble salt in the nickel plating bath is between about 2.0 to about 4.0 g/L. 
     
     
         28 . The method according to  claim 12 , wherein the at least one diol comprises both hexyne diol and butyne diol. 
     
     
         29 . The method according to  claim 28 , 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.