Plating method
View Patent ↗Copper plating baths containing a leveling agent that is a reaction product of a compound including a heteroatom chosen from nitrogen, sulfur and a mixture of nitrogen and sulfur, with a polyepoxide compound containing an ether linkage that deposit copper on the surface of an electronic device and in apertures on such substrate are provided. Such plating baths deposit a copper layer on the substrate surface that is substantially planar across a range of electrolyte concentrations. Methods of depositing copper layers using such copper plating baths are also disclosed.
1. A method of depositing copper on a printed circuit board comprising contacting a printed circuit board having blind vias with a copper electroplating bath comprising a source of copper ions, an electrolyte, and a leveling agent that is a reaction product of a compound selected from the group consisting of imidazole, triazole, tetrazole, benzimidazole, benzotriazole, piperidine, morpholine, piperazine, pyridine, oxazole, benzoxazole, pyrimidine, quinoline, and isoquinoline, with a polyepoxide compound containing an ether linkage; and then applying a current density for a period of time sufficient to deposit a copper layer on the printed circuit board, wherein the reaction product has a polydispersity of <2.5.
2. The method of claim 1 wherein the polydispersity is <2.
3. The method of claim 1 wherein the polyepoxide compound has the formula (I)
wherein R is (C 1 -C 10 )alkyl; and R 2 and R 3 are independently chosen from H or R, wherein n =1-20.
4. The method of claim 1 wherein the printed circuit board further comprises through holes.
5. The method of claim 1 wherein the copper electroplating bath has a throwing power of 70%.
6. The method of claim 1 wherein the compound is selected from the group consisting of imidazole and pyridine.