Crystalline chromium deposit

Abstract

An electroplating bath and a process for electrodepositing a crystalline chromium deposit on a substrate, in which the electroplating bath comprising trivalent chromium and a source of divalent sulfur, and substantially free of hexavalent chromium; immersing a substrate in the electroplating bath; and applying an electrical current to deposit a crystalline chromium deposit on the substrate, wherein the chromium deposit is crystalline as deposited, and/or has a lattice parameter of 2.8895+/−0.0025 Å, and/or the crystalline chromium deposit has a {111} preferred orientation.

1 . An electrodeposition bath for electrodepositing a crystalline chromium deposit, comprising:
 a source of trivalent chromium having a concentration of least 0.1 molar and being substantially free of added hexavalent chromium;   an organic additive;   a source of divalent sulfur;   a pH in the range from 4 to about 6.5;   an operating temperature in the range from about 35° C. to about 95° C.; and   a source of electrical energy applied between an anode and a cathode immersed in the electrodeposition bath.   
     
     
         2 . The electrodeposition bath of  claim 1  wherein the source of divalent sulfur comprises one or a mixture of two or more of a compound having the general formula (I):
   X 1 —R 1 —(S) n —R 2 —X 2   (I)
 
 wherein in (I), X 1  and X 2  may be the same or different and each of X 1  and X 2  independently comprise hydrogen, halogen, amino, cyano, nitro, nitroso, azo, alkylcarbonyl, formyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, carboxyl, sulfonate, sulfinate, phosphonate, phosphinate, sulfoxide, carbamate, polyethoxylated alkyl, polypropoxylated alkyl, hydroxyl, halogen-substituted alkyl, alkoxy, alkyl sulfate ester, alkylthio, alkylsulfinyl, alkylsulfonyl, alkylphosphonate or alkylphosphinate, wherein the alkyl and alkoxy groups are C 1 -C 6 , or X 1  and X 2  taken together may form a bond from R 1  to R 2 , 
 wherein R 1  and R 2  may be the same or different and each of R 1  and R 2  independently comprise a single bond, alkyl, allyl, alkenyl, alkynyl, cyclohexyl, aromatic and heteroaromatic rings, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, polyethoxylated and polypropoxylated alkyl, wherein the alkyl groups are C 1 -C 6 , and 
 wherein n has an average value ranging from 1 to about 5. 
 
     
     
         3 . The electrodeposition bath of  claim 1  wherein the source of divalent sulfur comprises one or a mixture of two or more of a compound having the general formula (IIa) and/or (IIb): 
       
         
           
           
               
               
           
         
         wherein in (IIa) and (IIb), R 3 , R 4 , R 5  and R 6  may be the same or different and independently comprise hydrogen, halogen, amino, cyano, nitro, nitroso, azo, alkylcarbonyl, formyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, carboxyl, sulfonate, sulfinate, phosphonate, phosphinate, sulfoxide, carbamate, polyethoxylated alkyl, polypropoxylated alkyl, hydroxyl, halogen-substituted alkyl, alkoxy, alkyl sulfate ester, alkylthio, alkylsulfinyl, alkylsulfonyl, alkylphosphonate or alkylphosphinate, wherein the alkyl and alkoxy groups are C 1 -C 6 , 
         wherein X represents carbon, nitrogen, oxygen, sulfur, selenium or tellurium and in which m ranges from 0 to about 3, 
         wherein n has an average value ranging from 1 to about 5, and 
         wherein each of (IIa) or (IIb) includes at least one divalent sulfur atom. 
       
     
     
         4 . The electrodeposition bath of  claim 1  wherein the source of divalent sulfur comprises one or a mixture of two or more of a compound having the general formula (IIIa) and/or (IIIb): 
       
         
           
           
               
               
           
         
         wherein, in (IIIa) and (IIIb), R 3 , R 4 , R 5  and R 6  may be the same or different and independently comprise hydrogen, halogen, amino, cyano, nitro, nitroso, azo, alkylcarbonyl, formyl, alkoxycarbonyl, aminocarbonyl, alkylaminocarbonyl, dialkylaminocarbonyl, carboxyl, sulfonate, sulfinate, phosphonate, phosphinate, sulfoxide, carbamate, polyethoxylated alkyl, polypropoxylated alkyl, hydroxyl, halogen-substituted alkyl, alkoxy, alkyl sulfate ester, alkylthio, alkylsulfinyl, alkylsulfonyl, alkylphosphonate or alkylphosphinate, wherein the alkyl and alkoxy groups are C 1 -C 6 , 
         wherein X represents carbon, nitrogen, sulfur, selenium or tellurium and in which m ranges from 0 to about 3, 
         wherein n has an average value ranging from 1 to about 5, and 
         wherein each of (IIIa) or (IIIb) includes at least one divalent sulfur atom. 
       
     
     
         5 . The electrodeposition bath of  claim 1  further comprising a source of nitrogen. 
     
     
         6 . The electrodeposition bath of  claim 5  wherein the source of nitrogen comprises ammonium hydroxide or a salt thereof, a primary, secondary or tertiary alkyl amine, in which the alkyl group is a C 1 -C 6  alkyl, an amino acid, a hydroxy amine, or a polyhydric alkanolamines, wherein alkyl groups in the source of nitrogen comprise C 1 -C 6  alkyl groups. 
     
     
         7 . The electrodeposition bath of  claim 1  wherein the source of electrical energy is capable of providing a current density of at least 10 A/dm 2  based on an area of substrate to be plated. 
     
     
         8 . The electrodeposition bath of  claim 1  wherein the source of electrical energy is capable of applying one or more of direct current, pulse waveform or pulse periodic reverse waveform. 
     
     
         9 . The electrodeposition bath of  claim 1  wherein when operated the bath deposits a functional chromium deposit that is crystalline as deposited. 
     
     
         10 . The electrodeposition bath of  claim 9  wherein the crystalline chromium deposit has a lattice parameter of 2.8895+/−0.0025 Å. 
     
     
         11 . The electrodeposition bath of  claim 9  wherein the crystalline chromium deposit has a {111} preferred orientation. 
     
     
         12 . The electrodeposition bath of  claim 9  wherein the crystalline chromium deposit further comprises carbon, nitrogen and sulfur in the chromium deposit. 
     
     
         13 . The electrodeposition bath of  claim 9  wherein the crystalline chromium deposit comprises from about 1 wt. % to about 10 wt. % sulfur. 
     
     
         14 . The electrodeposition bath of  claim 9  wherein the crystalline chromium deposit comprises from about 0.1 to about 5 wt % nitrogen. 
     
     
         15 . The electrodeposition bath of  claim 9  wherein the crystalline chromium deposit comprises an amount of carbon less than that amount which renders the chromium deposit amorphous. 
     
     
         16 . The electrodeposition bath of  claim 9  wherein the crystalline chromium deposit comprises from about 1.7 wt. % to about 4 wt. % sulfur, from about 0.1 wt. % to about 3 wt. % nitrogen, and from about 0.1 wt. % to about 10 wt. % carbon. 
     
     
         17 . The electrodeposition bath of  claim 9  wherein the crystalline chromium deposit is substantially free of macrocracking. 
     
     
         18 . A process for electrodepositing a crystalline chromium deposit on a substrate, comprising
 providing the electrodeposition bath of  claim 1 ;   immersing a substrate in the electrodeposition bath; and   applying an electrical current to deposit a crystalline chromium deposit on the substrate.   
     
     
         19 . A process for electrodepositing a crystalline chromium deposit on a substrate, comprising:
 providing an electroplating bath comprising trivalent chromium, an organic additive and at least one source of divalent sulfur, and being substantially free of hexavalent chromium;   immersing a substrate in the electroplating bath; and   applying an electrical current to deposit a crystalline chromium deposit on the substrate, wherein the chromium deposit is crystalline as deposited.   
     
     
         20 . A process for electrodepositing a crystalline chromium deposit on a substrate, comprising:
 providing an electroplating bath comprising trivalent chromium, an organic additive, and substantially free of hexavalent chromium;   immersing a substrate in the electroplating bath; and   applying an electrical current to deposit a crystalline chromium deposit on the substrate, wherein the chromium deposit is crystalline as deposited and the crystalline chromium deposit has a lattice parameter of 2.8895+/−0.0025 Å.