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Nickel or Copper Strike Electroplating Bath for Zincated Aluminum

IP.com Disclosure Number: IPCOM000085320D
Original Publication Date: 1976-Mar-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Missel, L: AUTHOR

Abstract

The zincate film on the aluminum is extremely delicate. It is reactive chemically which limits the nature of the first plating bath (the strike) to which it is exposed. Generally used is a copper cyanide strike, but the use of cyanide creates ecological problems. Entry into the bath is with the electrical current applied for immediate coverage to minimize chemical attack.

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Nickel or Copper Strike Electroplating Bath for Zincated Aluminum

The zincate film on the aluminum is extremely delicate. It is reactive chemically which limits the nature of the first plating bath (the strike) to which it is exposed. Generally used is a copper cyanide strike, but the use of cyanide creates ecological problems. Entry into the bath is with the electrical current applied for immediate coverage to minimize chemical attack.

Alternative acidic nickel strikes have not been successful because of the bath formulation which usually includes a high nickel ion concentration, active anions, pH too high for ductile nickel, and operation at an elevated temperature which accelerates the reaction between the bath and the reactive zinc deposit on the aluminum.

A nickel strike bath for plating on zincated aluminum provides:

a. A fully complexed nickel ion concentration to retard

chemical reduction.

b. Benign anions.

c. Mildly acidic pH for better adhesion.

d. Strong buffering action to make the bath more tolerant

to use and more resistant to change.

e. Stable nickel bath: and,

f. Room temperature operation.

The nickel plating bath can comprise a nickel salt of a weak acid such as nickel acetate or nickel formate, a common ion alkali or alkaline earth salt and a complexing agent. Suitable complexing agents are hydroxy substituted lower aliphatic carboxylic acids having 2 to 8 carbon atoms, from 1 to 6 hydroxyl groups and from 1 to 3 carboxyl groups, where the nicke...