GB1283715A - Electroless copper plating - Google Patents

Abstract

1283715 Electroless Cu bath SHIPLEY CO Inc 28 July 1969 [13 Aug 1968(3)] 37779/69 Heading C7F An aqueous electroless Cu bath comprises a source of Cu<SP>++</SP>, OH<SP>-</SP>, a source of HCHO, sufficient complexing agent to render said Cu<SP>++</SP> ions soluble in alkaline solution, and at least two additives selected from (1) a formaldehyde addition agent, (2) a solution soluble salt of a Group VIII metal, (3) an organic silicon compound, and (4) a hydrogen inclusion retarding agent, excepting any combination including both (3) and (4). (1) may be an alkali metal sulphite, bisulphite or phosphite, (2) is preferably the phosphate, nitrate, acetate or a halide of Fe, Co, Ni, Os, Ir, Pt, Ru, Rh or Pd, with Fe, Ni, Pt being preferred, (3) is a silane, e.g. SiH 4 ; disilane, tetramethylsilane, Et 4 Si, tetraphenylsilane, Me 2 SiCl 2 , or a polysiloxane, and (4) may be CN<SP>-</SP> or a soluble compound of V, Mo, Nb, W, Re, As, Sb, Bi, a lanthanide or an actinide, e.g. a molybdate, tungstate, vanadate, arsenate, rhenate or water soluble salts or oxides of said elements. The solution may contain a wetting agent; the Cu salt may be a halide, nitrate, or acetate, but the sulphate is preferred; the source of HCHO is HCHO itself or paraformaldehyde; and the complexing agent may be Rochelle salt, Na salicylate or tartrate, an EDTA salt or a derivative thereof, or triethanolamine, but is preferably a hydroxyalkyl-substituted tertiary amine. In use, a plastics substrate is sensitized and activated using SnCl 2 and PdCl 2 or a colloidal formulation of SnCl 2 and precious metal chloride, and is then plated in the above bath.