Solution and Process to Treat Surfaces of Copper Alloys in Order to Improve the Adhesion Between the Metal Surface and the Bonded Polymeric Material

Abstract

The invention concerns processes and solutions for the treatment of copper alloy surfaces, which are subsequently to be firmly bonded to polymeric material. The solution is used, in particular for firmly bonding lead frames to encapsulating molding compounds (polymeric material). The solution contains an oxidant, at least one acid, at least one adhesion-enhancing compound characterized in that the solution additionally contains fluoride ions in an amount of at least 100 mg per litre and chloride ions in an amount of 5 to 40 mg per litre. The solution is particularly useful for treatment of copper alloy surfaces, containing alloying elements selected from the group consisting of Si, Ni, Fe, Zr, P, Sn and Zn.

1 - 25 . (canceled) 
     
     
         26 . A solution for treating a surface of copper alloys to improve adhesion of polymeric materials thereto, comprising
 a) an oxidant   b) at least one acid   c) at least one adhesion-enhancing compound selected from the group consisting of triazoles, benzotriazoles, imidazoles, tetrazoles, purines and a compound which is a mixture of at least one nitrogen-containing, five-membered heterocyclic compound that does not contain sulfur, selenium or tellurium atoms in the heterocycle and at least one compound selected from the group consisting of sulfinic acids, selenic acids, telluric acids, heterocyclic compounds that contain at least one sulfur, selenium and/or tellurium atom in the heterocycle, as well as sulfonium, selenonium and telluronium salts, where the sulfonium, selenonium and telluronium salts are compounds of general formula A:   
       
         
           
           
               
               
           
         
         where A is S, Se or Te, R 1 , R 2  and R 3  are selected from the group consisting of alkyl, substituted alkyl, alkenyl, phenyl, substituted phenyl, benzyl, cycloalkyl and substituted cycloalkyl, where R 1 , R 2  and R 3  can be the same or different, and X −  is the anion of an inorganic or organic acid or hydroxide, with the proviso that the acid according to component b) is not a sulfinic, selenic or telluric acid according to component c) characterized in that the solution additionally contains: 
         d) fluoride ions in an amount of at least 100 mg per litre, 
         e) chloride ions in an amount of 5 to 40 mg per litre. 
       
     
     
         27 . The solution according to  claim 26 , characterized in that the triazole has the following chemical formula E1: 
       
         
           
           
               
               
           
         
       
       wherein R 17 , R 18  are selected from the group consisting of hydrogen, alkyl, substituted alkyl, amino, phenyl, substituted phenyl and carboxyalkyl, where R 17  and R 18  can be the same or different and can be a part of the homo- or heterocyclic ring condensed onto the triazole ring. 
     
     
         28 . The solution according to  claim 26 , characterized in that the triazole is selected from the group consisting of benzotriazole, methylbenzotriazole, ethyl benzotriazole and dimethylbenzotriazole. 
     
     
         29 . The solution according to  claim 26 , characterized in that the tetrazole has the following chemical formula E2: 
       
         
           
           
               
               
           
         
       
       wherein R 19  is selected from the group consisting of hydrogen, alkyl, substituted alkyl, halogenalkyl, amino, phenyl, substituted phenyl, benzyl, carboxy, carboxyalkyl, alkoxycarbonyl, aminocarbonyl and R 20  —CONH wherein R 20  is hydrogen, alkyl, substituted alkyl, phenyl or substituted phenyl. 
     
     
         30 . The solution according to  claim 29 , characterized in that the tetrazole is selected from the group consisting of 5-aminotetrazole and 5-phenyltetrazole. 
     
     
         31 . The solution according to  claim 26 , characterized in that it contains sulfinic acids selected from the group consisting of aromatic sulfinic acids and compounds of chemical formula B: 
       
         
           
           
               
               
           
         
       
       wherein R 4 , R 5  and R 6  are selected from the group consisting of hydrogen, alkyl, substituted alkyl, phenyl, substituted phenyl and R 7  —(CO)— wherein R 7  is hydrogen, alkyl, substituted alkyl, phenyl or substituted phenyl, where R 4 , R 5  and R 6  can be the same or different. 
     
     
         32 . The solution according to  claim 26 , characterized in that it contains formamidine sulfinic acid. 
     
     
         33 . The solution according to  claim 26 , characterized in that it contains aromatic sulfinic acids selected from the group consisting of benzene sulfinic acid, toluene sulfinic acids, chlorobenzene sulfinic acids, nitrobenzene sulfinic acids and carboxybenzene sulfinic acids. 
     
     
         34 . The solution according to  claim 26 , characterized in that it contains at least one heterocyclic compound selected from the group consisting of thiophenes, thiazoles, isothiazoles, thiadiazoles and thiatriazoles. 
     
     
         35 . The solution according to  claim 34 , characterized in that it contains at least one thiophene selected from the group consisting of compounds of chemical formula C: 
       
         
           
           
               
               
           
         
       
       wherein R 8 , R 9 , R 10 , R 11  are selected from the group consisting of hydrogen, alkyl, substituted alkyl, phenyl, substituted phenyl, halogen, amino, alkylamino, dialkylamino, hydroxy, alkoxy, carboxy, carboxyalkyl, alkoxycarbonyl, aminocarbonyl and R 12  —CONH— wherein R 12  is hydrogen, alkyl, substituted alkyl, phenyl or substituted phenyl, where R 8 , R 9 , R 10  and R 11  can be the same or different and can be a part of the homo- or heterocyclic ring condensed onto the thiophene ring. 
     
     
         36 . The solution according to  claim 34 , characterized in that it contains at least one thiophene selected from the group consisting of aminothiophene carboxylic acids, their esters and amides. 
     
     
         37 . The solution according to  claim 34 , characterized in that the thiazole is selected from the group consisting of compounds of chemical formula D: 
       
         
           
           
               
               
           
         
       
       wherein R 13 , R 14 , R 15  are selected from the group consisting of hydrogen, alkyl, substituted alkyl, phenyl, substituted phenyl, halogen, amino, alkylamino, dialkylamino, hydroxy, alkoxy, carboxy, carboxyalkyl, alkoxycarbonyl, aminocarbonyl and R 16  —CONH— wherein R 16  is hydrogen, alkyl, substituted alkyl, phenyl or substituted phenyl, where R 13 , R 14  and R 15  can be the same or different and can be a part of the homo- or heterocyclic ring condensed onto the thiazole ring. 
     
     
         38 . The solution according to  claim 34 , characterized in that the thiazole is selected from the group consisting of aminothiazoles and substituted aminothiazoles. 
     
     
         39 . The solution according to  claim 34 , characterized in that the thiadiazole is selected from the group consisting of aminothiadiazoles and substituted aminothiadiazoles. 
     
     
         40 . The solution according to  claim 26 , characterized in that the sulfonium salt is selected from the group consisting of trimethylsulfonium salts, triphenylsulfonium salts, methionine alkyl sulfonium salts and methionine benzyl sulfonium salts. 
     
     
         41 . The solution according to  claim 26 , characterized in that the nitrogen-containing, five-membered heterocyclic compound is selected from the group consisting of triazoles, tetrazoles, imidazoles, pyrazoles and purines. 
     
     
         42 . A solution according to  claim 26 , wherein the amount of fluoride ions is at least 0.5 g/l 
     
     
         43 . A solution according to  claim 26 , wherein the amount of fluoride ions is at least 2.0 g/l. 
     
     
         44 . A solution according to  claim 26 , characterized in that the fluoride ions are from a source selected from the group consisting of sodium fluoride, potassium fluoride, ammonium fluoride and tetrafluoro boric acid. 
     
     
         45 . The solution according to  claim 26 , characterized in that sulfuric acid is selected to be the acid for component b) in the solution. 
     
     
         46 . The solution according to  claim 26 , characterized in that the amount of chloride ions is 15 to 25 mg per litre. 
     
     
         47 . A process to pretreat copper alloy surfaces to allow a tight bond to be subsequently formed between the copper alloy surfaces and polymeric material in which the copper surfaces are brought into contact with the solution according to  claim 26 . 
     
     
         48 . A process to pretreat copper alloy surfaces according to  claim 47  characterized in that the copper alloy contains at least one alloying element selected from the group consisting of Si, Ni, Fe, Zr, P, Sn and Zn. 
     
     
         49 . A process according to  claim 48  wherein the copper alloy surface is on a lead frame and pretreated to create a tight bond between the copper alloy layers and moulding compounds.