Microetching solution
View Patent ↗The present invention related to an improved microetching solution and a method of using the improved composition for roughening a metal surface and increasing the adhesion strength of a metal layer to a subsequently applied layer. The microetching composition is an aqueous solution comprising cupric ion source, a pyridine derivative, multiethyleneamine, and an acid. In a preferred embodiment, the microetching solution of the invention also comprises a source of halide ions such as sodium chloride or hydrochloric acid.
1. A method of roughening a copper or copper alloy surface to provide improved adhesion of a layer subsequently applied thereto, comprising contacting the copper or copper alloy surface with a microetching composition comprising a cupric ion source, a pyridine derivative, multiethyleneamine, and an acid in an amount and for a period of time to roughen the surface.
2. The method according to claim 1 , wherein the cupric ion source is present in the microetching solution at a concentration of about 10-50 g/l.
3. The method according to claim 2 , wherein the cupric ion source is present in the microetching solution at a concentration of about 20-30 g/l.
4. The method according to claim 1 , wherein the pyridine derivative is picoline.
5. The method according to claim 1 , wherein the pyridine derivative is present in the microetching solution at a concentration of about 25-125 ml/l.
6. The method according to claim 5 , wherein the pyridine derivative is present in the microetching solution at a concentration of about 50-100 ml/l.
7. The method according to claim 1 , wherein the multiethyleneamine is present in the microetching solution at a concentration of about 100-1000 parts per million.
8. The method according to claim 7 , wherein the multiethyleneamine is present in the microetching solution at a concentration of about 100-600 parts per million.
9. The method according to claim 1 , wherein the acid is sulfuric acid.
10. The method according to claim 1 , wherein the microetching solution further comprises sodium chloride or hydrochloric acid.
11. The method according to claim 1 , wherein the acid is present in the solution in an amount sufficient to control the pH to between about 0.3-3.5.
12. The method according to claim 1 , wherein the microetching solution is applied by spraying the microetching solution onto the copper or copper alloy substrate with a dwell time of about 25-45 seconds.
13. The method according to claim 12 , wherein the dwell time is about 30 to about 40 seconds.
14. The method according to claim 1 , wherein the microetching depth of the copper or copper alloy surface is about 50-70 microinches.
15. The method according to claim 14 wherein the microetching depth of the copper or copper alloy surface is about 55-65 microinches.
16. The method according to claim 1 , wherein the multiethyleneamine is polyethyleneimine.
17. The method according to claim 16 , wherein the polyethyleneimine has a molecular weight between about 400 and about 600.