Abstract: An electroless copper plating bath uses a series of tetradentate nitrogen ligands. The components of the bath may be substituted without extensive re-optimization of the bath. The Cu-tetra-aza ligand baths operates over a pH range between 7 and 12. Stable bath formulations employing various buffers, reducing agents and ligands have been developed. The process can be used for metal deposition at lower pH and provides the capability to use additive processing for metallization in the presence of polyimide, positive photoresist and other alkali sensitive substrates.