Unlike conventional electroplating, no electrical current is required for deposition. The electroless bath provides a deposit that follows all contours of the substrate exactly, without building up at the edges and corners. A sharp edge receives the same thickness of deposit as a blind hole. Electroless nickel is the most widely used form of electroless plating. It offers unique deposit properties including uniformity of deposit properties within deep recesses, bores, and blind holes. Most commercial deposition is done with an acid phosphorous bath, which provides unique physical characteristics including excellent corrosion, wear and abrasion resistance, ductility, lubricity, solderability, electrical properties, and hardness. There are three types of electroless nickel: low phos, mid phos, and high phos.
- Low phos – has a thickness of .0011”. It is a hard deposit approaching hard chrome with no heat treatment necessary for hardness. It is comparable to boron electroless nickel. This deposit is used mainly for its hardness and wear properties.
- Mid phos – has a thickness of .00075”. This is the most widely used deposit. It has a bright uniform appearance and is used for both decorative and electronic applications.
- High phos – has a thickness of .0009”. It is a compressively stressed deposit with excellent adhesion, ductility, and superior corrosion resistance.