Electroless Nickel

Electroless Nickel (EN) plating provides a highly uniform binary deposit of nickel and an alloying element (i.e. phosphorous) that demonstrates excellent corrosion resistance even in "part-unfriendly" environments.  EN plating differs from traditional electroplating in that it is an autocatalytic process.  The presence of thin layer of nickel catalyzes the deposition of additional Ni deposits, continuing indefinitely while the part remains in contact with an appropriately balanced chemical solution.  The resultant thickness of the deposit is independent of current densities, and as a result extremely uniform surface coatings are achieved.  Thus, we recommend this finish for parts with complex geometries, blind holes, inner diameters, and etc. that require superior corrosion resistance in operation.

A Square offers a mid-phos (4-8% phosphorous content) as its standard EN plating process.  This bath produces semi-bright to bright deposits with excellent corrosion resistance, suitable for most applications.  In some unique circumstances, altering the alloying metal and/or alloy content of the deposit can have beneficial qualities from an engineering perspective.  These baths can be readily furnished to suit your parts wear and corrosion requirements.  Please contact our engineering team to discuss your parts and develop an EN finish that will suit your needs.

BENEFITS OF Electroless NIckel PLATING

  • Excellent corrosion resistance 
  • Uniform thickness of deposits
  • Deposits not current dependent-plates blind holes
  • Produces hard and wear-resistant deposits 
  • Good solderability
  • Decorative finish 
  • Less porous than other metals finishes 
  • Magnetic

DRAWBACKS OF EN Plating

Electroless nickel, as the name implies, does not use electrical current to build up a nickel metal finish.  This process has many beneficial characteristics but also comes with a few potential drawbacks:

  • Cost: Conventional electrolytic plating baths can have replenishment chemicals added to them more or less indefinitely without seeing significant changes in the behavior or the bath.  For electroless nickel baths, this is not the case.  The consumption of hypophosphite leads to an eventual build of up orthophosphite which is detrimental to the quality of the nickel plate at high concentrations.  Thus, EN baths have a finite lifetime and must be remade after several MTOs (metal turnovers).  This typically makes EN baths more expensive than their electrolytic nickel counterparts.
  • Bath Loading: To work properly and maintain a stable chemical balance, EN tanks must be properly loaded when close to operating temperature.  Low-volume parts with small surface areas can lead to improper loading of EN baths.  In turn, inordinately high prices in comparison to the amount of plating required result.  To address this issue A Square works to combine small orders from multiple customers when possible, thereby passing on the most economical prices.
  • Difficulty of Removal: EN coatings are extremely difficult to remove from the surface of a part after plating.  In most circumstances this is a positive attribute.  However, if a customer requires a previously plated part to be repaired, reworked, or stripped it is necessary to remove the EN plate.   At A Square we employ proprietary chemical strippers and sand-blasiting equipment to help with this process.

Electroless NIckel FINISHES

  • Semi-Bright
  • Bright

PLATING SPECIFICATIONS

  • MIL-C-26074
  • AMS 2404
  • AMS 2433
  • ASTM B-733
  • Customer directed specifications

In general, we plate our EN to a mid-phos (4-8% phos. content) range.  For specialty applications, please contact our engineering team to customize a solution to fit your part performance requirements.

PLATING METHODS

  • Rack Plating
  • Barrel Plating
  • Selective Plating

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