Electroless deposition of nickel on aluminum

Claim 1

A method for chemically depositing nickel on an aluminum or aluminum alloy surface comprising the steps of: (a) cleaning said surface; (b) immersing said surface in a first solution of buffered hydrofluoric acid and a nonaqueous solvent; (c) without rinsing, immersing said surface in a second solution comprising: ______________________________________ Grams/Liter H.sub.2 O ______________________________________ Nickel sulfate 1.1-50 Ammonium chloride 3-40 p-Toluene sulfonic acid 0.01-0.5 Buffered hydrofluoric acid 0.1-10 ______________________________________ (d) without rinsing, immersing said surface in an electroless plating bath comprising: ______________________________________ Per 1.5 liters H.sub.2 O ______________________________________ Nickel sulfate 15-45 g Sodium acetate 5-45 g Sodium hypophosphite 2.5-25 g Buffered hydrofluoric acid trace -10 ml p-Toluene sulfonic acid trace-0.15 g Formaldehyde trace-50 ml Ethanol trace-50 ml Boric acid trace-65 g ______________________________________ said electroless plating bath having a pH in the range of about 3.5 to 7 and a temperature in the range of about 25° C. to 95° C.

Claim 2

A method for chemically depositing nickel on an aluminum or aluminum alloy surface comprising the steps of: (a) cleaning said surface; (b) immersing said surface in a first solution of buffered hydrofluoric acid and a nonaqueous solvent; (c) without rinsing, immersing said surface in a second solution comprising: ______________________________________ Grams/Liter H.sub.2 O ______________________________________ Nickel sulfate 1.1-50 Ammonium chloride 3-40 p-Toluene sulfonic acid 0.01-0.5 Buffered hydrofluoric acid 0.1-10 ______________________________________ (d) without rinsing, immersing said surface in an electroless plating bath comprising: ______________________________________ Per 1.5 liters H.sub.2 O ______________________________________ Nickel sulfate 15-45 g Sodium acetate 5-45 g Sodium hypophosphite 2.5-25 g Buffered hydrofluoric acid trace -10 ml p-Toluene sulfonic acid trace-0.15 g Formaldehyde trace-50 ml Ethanol trace-50 ml Boric acid trace-65 g ______________________________________ said electroless plating bath having a pH in the range of about 3.5 to 7 and a temperature in the range of about 25° C. to 95° C.

Claim 4

A method for chemically depositing nickel on an aluminum or aluminum alloy surface having aluminum oxide thereon comprising the steps of: (a) cleaning said surface; (b) immersing said surface in a first solution of buffered hydrofluoric acid and a nonaqueous solvent which removes only said aluminum oxide and simultaneously activates said surface; (c) subjecting said surface to a second solution comprising an aqueous solution of a soluble nickel salt, a complex to give a common ion effect, buffered hydrofluoric acid, and a wetting agent which further activates said aluminum or aluminum alloy; and (d) immersing said surface in an aqueous bath comprising a reducible nickel salt, a hypophosphite reducing agent, an organic acid salt complexing agent, buffered hydrofluoric acid, bath stabilizers, buffers, and wetting agents; said bath having a pH in the range of about 3.5 to 7 and at a temperature in the range of about 25° C. to 95° C.

Claim 5

A method for chemically depositing nickel on an aluminum or aluminum alloy surface having aluminum oxide thereon comprising the steps of: (a) cleaning said surface; (b) immersing said surface in a first solution of buffered hydrofluoric acid and a nonaqueous solvent which removes only said aluminum oxide and simultaneously activates said surface; (c) subjecting said surface to a second solution comprising an aqueous solution of a soluble nickel salt, a complex to give a common ion effect, buffered hydrofluoric acid, and a wetting agent which further activates said aluminum or aluminum alloy; and (d) immersing said surface in an aqueous bath comprising a reducible nickel salt, a hypophosphite reducing agent, an organic acid salt complexing agent, buffered hydrofluoric acid, bath stabilizers, buffers, and wetting agents; said bath having a pH in the range of about 3.5 to 7 and at a temperature in the range of about 25° C. to 95° C.