Electroless Nickel Plating - Pretreatment

Pretreatment

Before performing electroless nickel plating, the material to be plated must be cleaned by a series of chemicals, this is known as the pre-treatment process. Failure to remove unwanted "soils" from the part's surface result in poor plating. Each pre-treatment chemical must be followed by water rinsing (normally two to three times) to remove chemicals that may adhere to the surface. De-greasing removes oils from surfaces, whereas acid cleaning removes scaling.

Activation is done with a weak acid etch, or nickel strike or, in the case of non-metallic substrate, a proprietary solution. After the plating process, plated materials must be finished with an anti-oxidation or anti-tarnish chemical such as trisodium phosphate or chromate, followed by water rinsing to prevent staining. The rinse object must then be completely dried or baked to obtain the full hardness of the plating film.

The pre-treatment required for the deposition of nickel and cobalt on a non-conductive surface usually consists of an initial surface preparation to render the substrate hydrophillic. Following this initial step, the surface is activated by a solution of a noble metal, e.g., palladium chloride. Silver nitrate is also used for activating ABS and other plastics. Electroless bath formation varies with the activator. The substrate is now ready for nickel deposition.