Electroless Nickel plating | Galvano Hengelo

Electroless Nickel plating

Electroless nickel (also indicated as autocatalytic nickel) coatings are alloys of nickel and phosphorous produced by autocatalytic chemical reduction with a reducer. They have multifunctional properties such as hardness, heat hardenability, abrasion, wear and corrosion resistance, magnetics, electrical conductivity, provide diffusion barrier and solderability. They are also used for repair of worn or wrong machined parts (ASTM B733).

To get a pore-free surface the coating thickness shall be at least 25 microns. We can plate a maximum layer thickness of 50 microns. With a thermal post treatment the coating can be hardened up to a factor 1.5 compared to “as plated” electroless Nickel, which is already almost twice the hardness of electroplated Nickel. Depending on the type of bath the phosphorous-content varies from 8 – 13 %. Higher phosphorus-content gives higher corrosion- and chemical resistance of the coating, but also results in less magnetism and less solderability of the coating.

Application of electroless nickel (EN) is especially suitable for complex shaped products because coating thickness can be controlled within ± 2 microns accuracy. This cannot be achieved in any electroplating process due to thickness variation resulting from non-uniform current distribution.

Properties of electroless nickel
Symbol NiP
Content Ni 87 - 92,5 %
Content P (mid-phos NiP-coatings,standard used on aluminium) 7,5 - 10 %
Content P (high-phos NiP-coatings,standard used on steel) 10 - 13 %
Density (mid-Phos / high-Phos) 8,1 / 7,8 ± 0,2 g/cm3
Melting point 850 - 880 °C
Electrical resistance 50 - 100 µΩ/cm
Magnetism mid-Phos / high-Phos Slight / Not
Solderability mid-Phos / high-Phos Good / Poor
Hardness as plated 500 - 600 HV
Hardness after thermal treatment (standard 16 hours 280 °C) 900 - 1000 HV

Base materials for electroless nickel plating: steel and aluminium.

Maximum product dimensions:
LxWxH = 1300 x 300 x 900 mm

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