Essay On Electroless Nickel Plating

CHAPTER 1

INTRODUCTION

1.1 Background of Study

Electroless nickel has been used widely in industries for many years especially in chemical, mechanical and electronic industry. Electroless process is an autocatalytic method in which the reduction of the metallic ions in the solution and the film deposition can be carried out through the oxidation of a chemical compound present in the solution itself, i.e., reducing agent, which supplies an internal current [1]. The most common reducing agent used in EN process is sodium hypophosphate (SHP). Due to its outstanding properties, such as thickness uniformity, hardness, corrosion and wear resistance, EN produced various type of applications e.g. in turbine or compressor blade (aerospace industry),

In this study electroless nickel phosphorus plating (Ni-P) deposited in the surface of copper substrates. It is well known that the EN is the autocatalytic deposition of Ni–P alloy from an aqueous solution on to a substrate without the application of external current [4]. The advantages of using EN are it gives good combination of uniform thickness with the hardness of deposit also good wear and corrosion resistance. EN coating is most widely accepted in engineering application due to its unique characteristics, including excellent corrosion, wear and abrasion resistance, ductility, lubrication, soldering, and electrical properties

thickness of the deposited nickel, hardness and other properties. These factors are depend on the electric current density, the voltage in volts applied, the concentration of salts, electroless plating bath composition, the bath temperature, pH, the nature of the base metal (cathode) and the additives used to give specific features to the nickel coating. Electroless plating bath contains a source of metal ions, reducing agent, complexing agent, stabilizer, buffering agent, wetting agent, and its parameters include controlled temperature and pH [1].

2.2 Phosphorus Content

The industry usually identifies EN coatings according to their phosphorus contents [5]. There have low phosphorus content (2 – 5% P) which provides maximum hardness and deposits uniformity also have better wear properties. Medium phosphorus content (6 – 9% P), providing a bright and uniform coverage of deposits on surface layer. High phosphorus (10 – 13% P) gives maximum corrosion resistance. The phosphorus content might change the properties of copper substrates either in good or bad way.

2.3 Sodium