Discusses the electroplating process details and associated criticalities

1. ahmadkhan_99@hotmail.com
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2. Sequence
 What & Why of Elctroplating
 Factors Influencing Electro Deposition
 Current density
 Cathode Efficiency
 Agitation
 Bath composition & Solution concentration
 Water Requirement
 The presence of impurities & Filtration
 Hydrogen Embrittlement and its Effects

3. What is Electroplating
 Electroplating is often called "electro deposition", and
the two terms are used interchangeably.
 As a matter of fact, "electroplating" can be considered
to occur by the process of electro deposition.
 Electro deposition is the process of producing a
coating, usually metallic, on a surface by the action of
electric current.

4. What is Electroplating
 The deposition of a metallic
coating onto an object is achieved
by putting a negative charge on
the object to be coated and
immersing it into a solution which
contains a salt of the metal to be
deposited (in other words, the
object to be plated is made the
cathode of an electrolytic cell)

5. What is Electroplating
 The metallic ions of the salt carry
a positive charge and are thus
attracted to the object
 When they reach the negatively
charged object (that is to be
electroplated), it provides
electrons to reduce the positively
charged ions to metallic form.

6. Why Electroplating
 Electroplating is a surface coating method that forms
an adherent layer of one metal on another
 To achieve the desired electrical and corrosion
resistance, reduce wear & friction, improve heat
tolerance and for decoration purposes

7. Requisites of Electroplating
 Clean substrates, solutions, and containers, etc.
Even low impurity levels would result in poor-quality films
 Good resist adhesion on the substrate is required
 The plating solution must have easy access to recesses, and
be compatible with the resist and substrate materials
 Uniform current distribution on the substrate surface

8. Factors Influencing Electro Deposition
 Current density
 Cathode Efficiency
 Agitation
 Bath composition and Solution concentration
 Water Requirement
 The presence of impurities (from poor cleaning, poor anodes, water
contaminants, poor water rinse before plating bath etc) & Filtration

9. Factors Influencing Electro Deposition
Current Density
 It is the application of current (Amperes) per unit area
 Current density for a particular bath are defined on the
basis of bath composition and required deposition
thickness and deposition rates
 Selection of current density is critical as poor selection
will result in defects in deposition quality like porosity,
poor deposition thickness
 Areas of the parts to be plated, must carefully be
calculated and current densities be selected accordingly

10. Factors Influencing Electro Deposition
Cathode Efficiency
 The ratio of the weight of metal actually deposited to
the weight that would have resulted if all the current
had been used for depositing it is called the cathode
efficiency
 Cathode efficiency in plating depends on:
 Electrolyte or bath
 Concentration of chemical composition
 pH and agitation
 Current density

11. Factors Influencing Electro Deposition
Cathode Efficiency
 Effects of poor Cathode Efficiency
If any of the depending factors are disturbed then
cathode efficiency will adversely suffer and result in:
 Poor deposition
 Process will be less cot effective in terms of
electricity consumption, solution composition and
early anode dissolution

12. Factors Influencing Electro Deposition
Agitation
 In a plating solution
 near the cathode, as metal is depleted, the solution becomes
less dense and tends to rise along the face of cathode
 Opposite occurs at the face of anode: solution tends to stream
down
 The solution is required to be agitated for homoginaty
 This problem, if not catered (through agitation) wherever
required, will cause
 non-uniform deposition of metal on the substrate
 Cathode efficiency will greatly suffer

13. Factors Influencing Electro Deposition
Bath Composition and Solution Concentration
 Metal Ions
 Electrolytes
 Organic Additives
 Brighteners
 Levelers
 Structure Modifiers
 Wetting Agents

14. Factors Influencing Electro Deposition
Bath Composition and Solution Concentration
1.Metal Ions
The metal ions to be plated are present in solution
2.Electrolytes
 Electrolytes give conductivity to the bath and high
concentration of the electrolyte ensures max conductivity
 Electrolytes control the bath PH value which if higher than
required level, will lead to deposition of Metal Hydroxyl ions
(not desired)
 Conductivity of electrolyte effects “Throwing Power” (ability
of the bath to give even deposit) of the bath

15. Factors Influencing Electro Deposition
Bath Composition and Solution Concentration
3.Organic Additives
 Brighteners
To cause an even, fine grained deposit
 Levelers
To produce a level deposit where otherwise there would be
rapid deposition of metal
 Structure Modifiers
To optimize particular deposit properties e.g hardness etc
 Wetting Agents
To accelerate the release of hydrogen gas bubbles from
solution surface

16. Factors Influencing Electro Deposition
Water Requirement
• Water is the main ingredient in all of the baths used and
its quality will effect the various operations
• Impurities present in most water supplies may include
dissolved mineral salts; organic compounds; suspended
solids and microorganisms
• De-ionized water requirement is critical
• Final rinse before Plating bath to avoid bath contamination
• Plating bath to avoid contamination
• Final rinse before dispatch to avoid stains caused by Ca, Mg salts
present in non treated water

17. Factors Influencing Electro Deposition
Presence of Impurities and Filtration
• Water is the main ingredient in all of the baths used and
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18. Hydrogen Embrittlement
 Hydrogen embrittlement is a generic term used to describe a
variety of fracture phenomena having a common relationship
to the presence of hydrogen in the metal as a solute or in the
atmosphere as a gas
 In general any process producing atomic H at a metal surface
will induce considerable hydrogen absorption in that metal
(Electroplating, Electroless plating, Acid Pickling, Electrolytic
cleaning)
 Hydrogen embrittlement alters the Fatigue limit characteristics
of the metal

19. Effects of Hydrogen Embrittlement
 Corrosion reactions can generate Hydrogen, and choosing
proper coating to prevent corrosion is important
 Problems as a result of H embrittlement/hydriding:
• Failure of aircraft components
• Blisters in Cu, Al, and Steel components
• Reductions in mechanical properties of materials