PRODUCTION OF OPTICAL QUALITY ELECTROLESS NICKEL (EN) COATING ON COPPER SUBSTRATE

Introduction

It is a material dependent and variable hardness technique suitable for production of high quality coated metal optics. It is a group of coatings. The selection of type of electroless nickel needs to be made keeping in view its end applications. This coating is nanocrystalline with grain size of 10 -15 oA (1-1.5 nm) and the coating can be deposited with zero stress or slight compressive stress. 

 Applications

Metal and coated metal optics are of particular importance in advanced astrophysical, directed energy weapons systems, lasers and alternative energy applications.
In defence applications, a few of the products that will require optical components and system are:-

  1. Fire control systems
  2. Pointer – trackers
  3. Forward Looking Infrared System (FLIR)
  4. Night Vision Systems
  5. Advanced surveillance device etc. 

Specifications

(a)  Material:  The four different specifications of copper available in the market for making substrates are:-

(i)

Commercial copper (ASTM B-846).

(ii)

Electrolytic Tough Pitch (ETP) copper (ASTM B5).

(iii)

Deoxidised High Phosphorous (DHP) copper (ASTM B-846).

(iv)

Oxygen Free High Conductivity (OFHC) copper (ASTM B-170).

(b)  Electroless Nickel Plating Solution: The solution that gives Ni-P alloy coating (P content around 10.5%) is used. One such plating solution commercially available is Ginplate Ni 422. This is available in three liquid concentrates, these are:-

(i)

Ginplate Ni 422 A

(ii)

Ginplate Ni 422 B

(iii)

Ginplate Ni 422 C

Note:- A & B are used for make up and A is used with C for replenishment. 

 Electroless Nickel Coating Process

The part to be plated, is ultrasonically cleaned by suspending the part in organic solvent for 5 minutes to get rid of the traces of machine lubricants / coolants / soils from the surface of the components. In final cleaning process acid bright dip, using Gictane Q 533 can also be used. 

After proper preparation of solution, parts to be EN coated are simply immersed in the Ginplate 422 solution for the required time to obtain the desired thickness of EN coating. 

 Infrastructural Facilities

Small laboratories with facility to analyse pH of Ginplate 422 solution both during make-up and EN plating operation, and space for installation of pre-treatment and plating tank. 

 Manpower

  1. One chemist and one technician to observe the process and testing of the chemicals. 

  2. One electrician for electrical connections and troubleshooting.

    3. For details contact :
       

        Head, Technology Transfer & Collaboration Division,
        BHABHA ATOMIC RESEARCH CENTRE,
        TROMBAY, MUMBAI - 400 085
        Fax : 091-022-25505151
        Email : technology@barc.gov.in
      

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