METHOD FOR CHEMICAL NICKEL PLATING OF ALUMINIUM CONTACT PADS BEFORE IMMERSION PLATING Russian patent published in 2016 - IPC C23C18/24 C23C18/36 

FIELD: chemistry.

SUBSTANCE: invention relates to chemical nickel plating and can be used for metal coating of aluminium contact sites before immersion plating. Method involves etching aluminium contact pads with subsequent hot and cold flushing, treatment in nitric acid, followed by washing, zincate treatment and chemical deposition of nickel coating of hypophosphite solution. Treatment in nitric acid, followed by washing and zincate treatment of contact pads is performed twice, after zincate treatment is followed by hot and cold washing. Etching is carried out in 5 % solution of caustic soda at temperature 38-43 °C for 10-60 s, treatment in nitric acid is carried out in 32.5 %-solution for 10-50 s, and zincate treatment is carried out for 10-50 s in a solution containing, g/dm³: zinc oxide - 50, sodium hydroxide - 250. Nickel coating is applied at temperature of 80-95 °C with subacidic hypophosphite solution with pH 5.0-6.0, containing, g/dm³: nickel sulphate in terms of Ni²⁺ - 4.5-6.0, sodium hypophosphite - 20-25, amino acetic acid - 7-20, sodium acetate - 10-15, wherein method comprises performing processes in solutions at loading density 0.5-2.5 dm²/dm³.

EFFECT: higher density and uniformity of thickness of contact deposited zinc.

1 cl