Formaldehyde-free electroless metal plating compositions and methods

Abstract

Formaldehyde-free electroless metal plating solutions include glyoxylic acid or salts thereof in combination with tertiary amines which stabilize the glyoxylic acid and salts. The electroless metal plating solutions are environmentally friendly, stable and deposit bright metal deposits on substrates.

What is claimed is: 
     
         1 . A composition comprising one or more sources of metal ions, one or more sources of glyoxylic acid, salts or mixtures thereof and one or more tertiary amine compounds, salts, halides or mixtures thereof having a formula: 
       
         
           
           
               
               
           
         
       
       wherein R 1 , R 2  and R 3  may be the same or different and are linear or branched, substituted or unsubstituted hydroxy(C 1 -C 10 )alkyl, linear or branched, substituted or unsubstituted carboxy(C 1 -C 10 )alkyl, linear or branched, substituted or unsubstituted (C 1 -C 10 )alkylamine, linear or branched, substituted or unsubstituted (C 1 -C 10 )alkyl phosphonic acid, a moiety having a formula: 
       
         
           
           
               
               
           
         
       
       wherein R 4  and R 5  may be the same or different and are linear or branched, substituted or unsubstituted hydroxy(C 1 -C 10 )alkyl, linear or branched, substituted or unsubstituted carboxy(C 1 -C 10 )alkyl, linear or branched, substituted or unsubstituted (C 1 -C 10 )alkylamine, linear or branched, substituted or unsubstituted (C 1 -C 10 )alkyl phosphonic acid, or moiety —(CH 2 ) a —N—((CH 2 ) b ) 2 —(P(O)(OH) 2 ) (IIa) where a and b may be the same or different and are integers of 1 to 6, m is an integer from 1 to 6, B is a moiety having a formula: 
       
         
           
           
               
               
           
         
       
       wherein R 6  and R 7  may be the same or different and are hydrogen, hydroxyl, carboxyl, hydroxy(C 1 -C 3 )alkyl, carboxy(C 1 -C 3 )alkyl, (C 1 -C 3 )alkyl, or B may be a substituted or unsubstituted (C 5 -C 6 )cycloalkyl ring and m=1, A is a chemical bond with the nitrogen of formula (I) or a moiety having a formula: 
       
         
           
           
               
               
           
         
       
       wherein R 8 , R 9 , R 10  and R 11  are the same or different and are hydrogen, hydroxyl, (C 1 -C 3 )alkyl, n, p, q may be the same or different and are integers of 1 to 6, with the proviso that when any two of R 1 , R 2  and R 3  are carboxymethyl moieties or salts thereof the third cannot be formula (II) where A is a chemical bond, m is 2, R 6  and R 7  are hydrogen and R 4  and R 5  are carboxymethyl moieties or salts thereof; and a molar ratio of the one or more tertiary amine compounds to the glyoxylic acid or salts thereof is 0.05:1 to 15:1, the compositions are formaldehyde-free. 
     
     
         2 . The composition of  claim 1 , wherein the one or more sources of glyoxylic acid is chosen from non-dissociated glyoxylic acid, dihydroxy acetic acid, a dihaloacetic acid and the bisulphite adduct of glyoxylic acid. 
     
     
         3 . The composition of  claim 1 , wherein the salts of glyoxylic acid are chosen from alkali metal salts and ammonium salt of glyoxylic acid. 
     
     
         4 . The composition of  claim 1 , wherein the one or more tertiary amines are chosen from triethanolamine, 2-[bis(2-hydroxyethyl)amino]acetic acid and its salts, N-(2-hydroxyethyl)iminodiacetic acid and its salts, nitrilotriacetic acid, nitrilo(3-propionic)diacetic acid and its salts, nitrilotripropionic acid and its salts, N,N-bis(2-hydroxypropyl)ethanolamine, 1-[bis(2-hydroxyethyl)amino]-2-propanol, 2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)-1,3-propanediol, N,N-Bis(carboxymethyl)-DL-alanine and its salts, triisopropanolamine, L-glutamic acid N,N′-diacetic acid and its salts, N,N,N′,N′-tetrakis(2-hydroxypropyl)ethylenediamine, N,N,N′,N′-tetrakis(2-hydroxyethyl)ethylenediamine, 1,3-Diamino-2-hydroxypropane-N,N,N′,N′-tetraacetic acid and its salts, ethylenediaminetetrapropionic acid and its salts, propylenediaminetetraacetic acid and its salts, N-(2-hydroxyethyl)ethylenediamine-N,N′,N′-triacetic acid and its salts, diethylenetriamine pentaacetic acid and its salts, triethylenetetramine-N,N,N′,N″,N′″,N′″-hexaacetic acid and its salts, methyl diethanolamine, methyliminodiacetic acid and its salts, tris(carboxymethyl)ethylenediamine, 1,2-diaminocyclohexanetetraacetic acid and its salts, N-(2-aminoethyl)-trans-1,2-diaminocyclohexane-N,N,N-pentaacetic acid and its salts, ethylene glycol tetraacetic acid and its salts, diethylene triamine pentamethylene phosphonic acid and its salts, (ethylenedinitrilo)-tetramethylenephosphonic acid and its salts, (nitrilotrimethylene)triphosphonic acid and its salts. 
     
     
         5 . The composition of  claim 1 , wherein metal ions are chosen from copper ions, tin ions, nickel ions, silver ions, gold ions and mixtures thereof. 
     
     
         6 . The composition of  claim 1 , further comprising accelerators, uniformity enhancers, stabilizers, grain-refiners, complexing agents, chelating agents, additional reducing agents, pH adjusting agents, antioxidants and surfactants. 
     
     
         7 . A method comprising:
 a) providing a substrate;   b) applying the composition of  claim 1  to the substrate; and   c) electroless plating metal on the substrate.   
     
     
         8 . The method of  claim 7 , wherein the substrate comprises a plurality of through-holes and further comprising:
 d) desmearing the through-holes; and   e) plating metal on walls of the through-holes.