Nickel plating is a surface finishing technique of plating a thin layer of nickel on an object. Nickel plating can be used as decorative or functional purpose. There are two types of nickel plating including electrolytic nickel plating and electroless nickel plating. Electrolytic nickel plating involves two electrodes, electrolyte and a DC power source combined together to form a closed loop. Under the influence of current, nickel ions in the electrolyte will shift to the cathode and form a thin layer of nickel on it. Whereas, electroless nickel plating is a process without the use of a power source to drive the process. It is an auto-catalytic chemical process which uses a reducing agent (e.g. hydrated sodium hypophosphite) to reduce nickel ions to metal and deposit on an object. Normally, phosphorous and boron will be added to deposit a layer of nickel-phosphorous or nickel-boron. Electrolytic nickel plating and electroless nickel plating are two distinctly different processes and the layers formed result in different properties. Electroless nickel plating has numerous advantages over electrolytic nickel plating which are summarized in the following table.
|Electrolytic Nickel||Electroless Nickel|
|Since an external DC source is necessary to electrolytic nickel process, high current density area (e.g. edges or corners) will be plated thicker deposit. As a result, the thickness uniformity greatly depends on the current density passing through different locations of a part. Thickness is controlled by the current density and reaction time.||It is an auto-catalytic process without using an external power source. Hence, uniform thickness all over a part or even on a part with an intricate shape can be achieved. Thickness is controlled by the reaction time.|
|Deposit is mainly a pure nickel layer.||Deposit layer is an alloy of nickel (85+ %) and phosphorous/boron. Different alloys will exhibit different properties.|
|Deposit possesses a microhardness ranging from 250~ 450 VHN.||Deposit possesses a better microhardness ranging from 340~600VHN.
Hardness can be further enhanced up to 1000~1150VHN when the deposit is performed heat treatment.
|Thin deposit is porous surface structure so its corrosion resistance is not as good as that of electroless plating.||Nickel deposit alloyed with either phosphorous or boron normally possesses better corrosion due to its less porous surface structure. Besides that, it has better wear resistance and hardness.|
|Generally, it doesn’t possess lubricity and non-galling characteristics.||Good lubricity and non-galling characteristics.|
|Relatively high magnetic property.||Less magnetic property with high amount of doping of phosphorous. It means that magnetic property is able to be controlled by the doping amount of phosphorous.|
At NICA, we offer solutions in surface finishing and treatment using nickel plating and other technologies for PCB, sanitary ware, smart phone and computer parts manufacturing, photovoltaic, automotive, GMF, IC substrate and aerospace industries. NICA provides turnkey solutions for our clients from initial system development phase to managing their system lifecycle ensuring our client’s success in their operations.