Electroless nickel

Features of galvanic treatments Electroless nickel

The chemical nickel-plating process (or electroless nickel plating) consists of a deposition of nickel without the use of electric current: the presence in the treating solution of a chemical reducing agent (typically sodium hypophosphite) triggers a controlled autocatalytic reaction, with a co-deposition of phosphorus (resulting from the reaction of the hypophosphite).
It is a process that is very developed in the last 15-20 years: in fact, in the late 1990s, the Galvanic Paciotti had two bathrooms to 400 liters, today there are nine, with volumes from 250 up to 2200 liters.

Nook for microelectronics/defense - Nickel chemistry on aluminum

The chemical nickel can be deposited on a wide range of materials: aluminum alloys, copper and its alloys (including copper-tungsten), ferrous alloys (stainless steel, kovar, invar, mu-metal, ...) and titanium (Ti6Al4V alloy), with thicknesses ranging from 2-3μ up to 50μ (and beyond), according to the needs. The first advantage of chemical nickel plating is the distribution of the thickness on the treated objects, much more uniform compared to electrolytic nickel plating (with electric current), especially in the case of complex geometric shapes; for example you can nickel-plate the interior of tubes without the aid of auxiliary anodes (it’s sufficient to ensure a good handling of the piece).

The chemical nickel can be applied as a final treatment (corrosion protection, wear resistance, general improvement of the treated surfaces), or as an intermediate layer (barrier) before subsequent treatments such as gold, silver, tin, etc.

SVarious types of baths, which differ in the different percentage of co-deposited phosphor with different characteristics from the deposit obtained, are available (see table), providing the ideal solution for any type of application.
The average and high types phosphorus meet about 80% of the requests of our current customers.

Housing and cover for civil telecommunications equipment and defense: Chemical nickel plating on aluminum basis.

Some general criteria for the choice of the type of chemical nickel:

• LOW PHOSPHORUS (1-3%): 

a) when the main requirement is the hardness and wear resistance;
b) in presence of high mechanical and or thermal stresses (thermal shock): it limits the risk of cracking of the deposit, due to the compressive internal stresses;
c) when low electrical resistivity is required (in relation to the other types of chemical nickel).

• MEDIUM-LOW (4-6%) AND MEDIUM PHOSPHORUS (7-9%):

a) general applications in mechanical, aeronautical industries, space and microelectronics sectors; 
b) good resistance to corrosion.
c) it is the most used as a substrate (or barrier layer) before subsequent treatments.

• HIGH PHOSPHORUS (10-13%):

a) where the main requirement is the corrosion resistance;
b) applications requiring the absence of magnetism;
c) where it is required a relatively flexible coating, resistant to mechanical or thermal stress with limited risk of cracking.
d) applications in the food industry;
e) compliance with the European ROHS directive.

SPECIAL SOLUTIONS ON REQUEST

For special applications, evaluating the performance/cost ratio, the following offers may be available:

• Nickel-boron: chemical nickel with co-deposition process with boron instead of phosphorus: the deposit is particularly suitable for the brazing of components especially in the field of microelectronics.
  
  
• Nickel-PTFE: the co-deposition of particles of PTFE (Teflon®) in the chemical nickel-plating process allows to obtain deposits with a particularly low coefficient of friction, for applications where the smoothness is an essential requirement.