1. K. Parker, "Recent Advances in Electroless Nickel Deposits, 8th Interfinish Conference," 1972 (Basel) Bath Composition and Characteristics

Electroless nickel coatings are produced by the controlled chemical reduction of nickel ions onto a catalytic surface. The deposit itself is catalytic to reduction, and the reaction continues as long as the surface remains in contact with the electroless nickel solution. Because the deposit is applied without an electric current, its thickness is uniform on all areas of an article in contact with fresh solution.

Electroless nickel solutions are blends of different chemicals, each performing an important function. Electroless nickel solutions contain:

• A source of nickel, usually nickel sulfate

• A reducing agent to supply electrons for the reduction of nickel

• Complexing agents (chelators) to control the free nickel available to the reaction

• Buffering agents to resist the pH changes caused by the hydrogen generated during deposition

• Accelerators (exultants) to help increase the speed of the reaction

• Inhibitors (stabilizers) to help control reduction

• Reaction byproducts

The characteristics of an electroless nickel bath and its deposit are determined by the composition of these components.

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