Solution equilibrium characteristics of two electroless copper baths containing EDTA and tartrate as the complexing agents were studied as functions of pH. Equilibrium diagrams were constructed for both Cu-tartrate and Cu-EDTA systems. It was determined that copper is chiefly complexed as Cu2L2 in acidic conditions and as Cu(OH)(2)L-2(-4) in alkaline conditions in the tartrate bath, and as CuA(-2) in the EDTA bath, where L and A are the complexing tartrate and EDTA ligands, respectively. Electroless copper deposition rates were studied from a tartrate bath on thermally activated palladium-catalysed polyimide substrates as functions of copper and formaldehyde concentrations, and pH.