Electroless nickel alloy plating bath and process for depositing thereof
AssigneeOMG Electronic Chemicals, Inc.
InventorsAurora Marie Fojas NYE, Jerry G. DU, Robert C. ANDRE
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Abstract
An aqueous nickel phosphorus tin alloy electroless plating bath and process for depositing a nickel phosphorus tin alloy onto a substrate, particularly an aluminum substrate for memory disk applications, wherein the nickel phosphorus tin alloy deposit provides enhanced thermal stability, as defined by the inhibition of crystallization and suppression of magnetization upon high temperature annealing when compared to typical NiP deposits.
Claims28
An aqueous nickel phosphorus tin alloy electroless plating bath for plating a substrate, the plating bath comprising:
- at least one source of nickel ion, wherein the at least one source of nickel ion is provided in a range from about 1-15 g/L;
- a hypophosphite salt as a reducing agent, wherein the hypophosphite salt is provided in a range from about 10-50 g/L;
- at least one chelating agent, wherein the at least one chelating agent is provided in a range from about 1-65 g/L;
- an auxiliary bath stabilizer, wherein the stabilizer is provided in a range ≦1 g/L;
- and
- at least one source of stannous ion, wherein the at least one source of stannous ion is provided in a range from about 0.001 to about 0.1 g/L, wherein the plating bath is maintained at a pH between 4-5.
A method of electrolessly plating a surface of a substrate with a ternary alloy, the method comprising the steps of:
- providing a substrate to be plated;
- submerging the substrate into an aqueous nickel phosphorus alloy plating bath which is heated to a temperature of less than about 96° C. (about 205° F.) and maintained at a pH between 4-5, wherein the plating bath comprises:
- at least one source of nickel ion, wherein the at least one source of nickel ion is provided in a range from about 1-15 g/L;
- a hypophosphite salt as a reducing agent, wherein the hypophosphite salt is provided in a range from about 10-50 g/L;
- at least one chelating agent, wherein the at least one chelating agent is provided in a range from about 1-65 g/L;
- an auxiliary bath stabilizer, wherein the stabilizer is provided in a range ≦1 g/L;
- and
- at least one source of stannous ion, wherein the at least one source of stannous ion is provided in a range from about 0.001 to about 0.1 g/L;
- and
- plating the nickel phosphorus tin alloy onto the surface of the substrate at a rate of about 4 microinches/minute to form a plated substrate, wherein the plated substrate has a thickness of at least 40 microinches and the nickel phosphorus tin alloy includes between 3-9% tin and between 7-12% phosphorus.
Dependencies are inferred from the claim text.