Electroplating Process: How does it work, its Process and Applications
Introduction
A crude metal will likely corrode due to environmental conditions. In order to protect it, manufacturers can use the process of electroplating.
In this post, we’ll help you understand what is electroplating, the different methods of electroplating, and several common metals used in the process.
Table of Contents
What is Electroplating?
Electroplating is a process by which metal ions migrate via a solution from a positive electrode to a negative one. An electrical current passing through the solution causes objects at the cathode to be coated by the metal in the solution.
Many products have electroplated parts; the most popular items are electroplated jewelry. A car has numerous electroplated parts, including its bumpers, hubcaps, grilles, door handles, and other decorative trimmings. The body of the car and its various automotive parts are electroplated to prevent rust, protect it from heat and other potential damage.
The aerospace industry also uses electroplated parts similar to cars, but they use electroplating to increase the hardness and thickness of the airplane’s body to make it resistant to atmospheric and other environmental conditions or to use lighter materials and have functional coatings with specific properties. Electronic devices, including computers and smart phones, also have electroplated parts that allow for better conductivity of electrical current as well as prevent overheating during charging.
Electroplating Methods
Barrel Plating
The primary function of barrel plating is to provide an economical means to electroplate manufactured parts that also meet specific finishing requirements. This method is best for high-volume plating with uniform coverage.
The parts that need to be plated are placed inside a barrel and immersed in the metal plating solution. The barrel slowly rotates and electrical contact is achieved through the use of danglers or centerbars located inside the barrel. The mechanical energy of the rotation produces a burnishing action that helps to clean and descale the parts to a greater degree than rack plating. The tumbling action is also responsible for the high degree of plating uniformity which can be achieved in the barrel.
Rack Plating
Rack plating is used for coating large, complex or fragile parts where they are hung on a “rack” and then submerged in the plating solution in a tank. For electrical contact, metal bands or hooks are used to hold the parts that need to be plated.
In this method, damage to delicate parts are lessened, intricate contours and deep crevices are evenly plated, and the finishes are generally of higher quality than barrel plating. With this method and by using specific masking products and techniques, it is possible to produce selective deposits.
Reel-to-reel Plating
Reel-to-reel plating is an efficient and economical method to plate strips of manufactured products or reels of raw material before they are used for parts. Electronics and semiconductor components are the primary parts that are plated using this method. Typical examples of these parts include connector contacts, lead frames, connecting devices, leads, headers, or the solid strip materials from which contacts and components are subsequently formed.
The process starts by loading the reels onto a de-reeling station. Thereafter, the material is fed through various electroplating processes using a capstan system. At the end of the line is a take-up system that re-spools the material once the desired metal finish is achieved.
The process can be summarized in 3 stages:
Inspection
Finished products in electroplating are subjected to a number of tests to ensure good plating quality. Typically, these tests may include:
Adhesion: By twist, bend bake and/or tape
Appearance: Visual and microscopic (to the level of magnification contractually agreed on)
Solderability
Bondability: E.g. ultrasonic wire bonding
Porosity: Can include nitric acid vapor or immersion, electrolytic or gas techniques
Thickness: X-ray Fluorescence (XRF) or microsection
Common Types of Metals Used for Plating
Copper Plating
Copper layers are very decorative and are good electrical conductors. Depending on the additions, hardness can vary between 90 HV and more than 200 HV. For functional applications, a copper layer is often covered by another metallic layer.
Advantages
Copper layers have excellent heat and electrical conductivity
A very wide range of properties are achievable by changing the deposition conditions
A large number of metals and plastics can easily be plated with copper
Copper plating is an essential step in the fabrication of printed circuit boards
Limitations
Copper may tarnish in air or when touched; this necessitates a metallic or organic top layer
Nickel Plating
Nickel layers are not only decorative, but also corrosion and wear-resistant. Depending on the organic additions, the deposit can exhibit hardness values between 150 and 500 HV. The metal layer may have varying levels of internal stress and ductility. Bright nickel looks yellowish in daylight and tarnishes easily; for this reason, it is commonly covered with a top layer such as chrome or gold.
Advantages
Attractive-looking decorative layer
Corrosion and wear-resistant
Different bath compositions can be used for vastly differing applications
Can be applied on a wide variety of substrate materials
A good underlayer for other surface coatings
Limitations
Discoloring of nickel in air necessitates the use of a top layer; for electronics, a final coat of gold may be necessary
Nickel could cause allergic skin reactions
Tin Plating
Tin offers a good level of conductivity, making it extremely useful in the manufacturing of various electronic parts. It is also widely used in the food production industry.
Advantages
Corrosion and adhesive wear resistant
Good solderability
Resistance welding is possible after deposition of tin
Good electrical properties
Approved for use in food industry (FDA-approved)
Disadvantages / Limitations
High-strength steel is sensitive to hydrogen embrittlement
For some substrates, heat treatment is necessary in order to prevent brittleness
Under certain conditions, whisker growth could appear from the tin layer which could cause short circuits in electrical contacts
Gold Plating
Gold layers have many technical applications, related to their excellent corrosion resistance, low electrical contact resistance and good electrical and heat conductivity.
Gold layers can be deposited on a large variety of substrates such as metals, plastics, ceramics and natural materials (such as leather and wood), in all cases using an intermediate copper or nickel layer.
Advantages
Outstanding electrical conductivity
Excellent heat conductivity
Good solderability
Good corrosion and chemical resistance
Disadvantages
High cost, which can fluctuate during the year
Softness of the unalloyed metal
Silver Plating
Due to its good electrical conductivity, silver is very often used in electrical and electronic applications.
Advantages
Outstanding electrical and heat conductivity
Disadvantages
Tarnishes readily in air under certain conditions and in the presence of sulphur-containing compounds
Palladium Plating
Palladium is well suited to plating applications where the prevention of oxide formation is required. It has a high melting point of 1554°C and costs less (per ounce troy) than gold. In most general electronics applications, palladium is an excellent substitute for gold.
Advantages
Cost-effective plating; relatively inexpensive compared to other precious metals
Corrosion-resistant; it is about as resistant to corrosion as gold, with a natural resistance against oxidation
Relatively hard; despite being considered a softer metal, it is still harder than gold, which helps against impact and denting
Diffusion-resistant; copper diffuses rapidly through gold but not palladium, making palladium an excellent coating for copper objects
Very good solderability
Disadvantages
Reduced heat resistance; Palladium has a lower melting point than gold, making it easier to deform under extreme heat
Not resistant to acid; Vulnerability to strong acids limits the types of applications where palladium can be used
More prone to cracking; when placed under stress, palladium is more prone to cracking than gold because of its hardness
Electroplating: Definition, Working, Application & Factors Affecting
Electroplating refers to the process of coating a metal onto another metal or alloy with the help of an electric current. It is also known as electrochemical deposition or electrodeposition.
In this article, we are going to learn the basic concepts of the electroplating process, its applications, definition, working principle, and types. We will also explore the examples of the electroplating process, factors affecting it, its advantages and uses with diagram.
What is Electroplating?
Electroplating is a process of coating or plating a metal onto another by hydrolysis It is usually done to avoid metal corrosion or for ornamental purposes.
The main driving force behind the electroplating is electric current.
Electroplating is usually done for ornamental purposes or for increasing the life of a more important metal by coating it with a less important metal.
For example, you have seen your mother purchasing golden ornaments from the market at a much cheaper price than gold and you wonder why the ornament cost so less. The reason behind it is that those are made up of copper or any other cheaper metal but electroplated with gold hence costing less and appearing shiny.
Electroplating Process – Principle
The working principle of Electroplating is that when two metals acting as electrodes are immersed in the salt of anode metal and a potential difference is created between them by supplying current. Then the metal on the anode oxidizes and dissolves into the electrolyte salt and later gets reduced and deposit itself as a thin layer on the metal on cathode.
The process of electroplating is based on the following principle:
Electric current is used to reduce dissolved metal cations, resulting in a thin, coherent metal coating on the electrode, which is also the main
principle of electroplating.
In the electrical oxidation of anions on a solid substrate, such as the production of silver chloride on silver wire to make silver chloride electrodes, electroplating is frequently used.
Electroplating is mostly used to change the surface properties of an object (for example, corrosion resistance, lubricity, and abrasion resistance), but it can also be used to add thickness or create objects by electro-shaping.
Electroplating Process- Principle
Electroplating Process – Setup
The setup of Electroplating involves the following components:
Anode:
The metal to be used for coating
Cathode:
The metal on which coating is to be done.
Electrolyte:
It should be the aqueous salt solution of anode metal.
Power Source:
Usually DC supply
For instance, Electroplating is done with a brine or acidic or basic or metal salt solution, a battery, wires, and alligator clips that hold carbon rods attached to the metal to be electroplated and the metal to be stacked in an electroplating device. Following are some examples of electroplating setup
Electrode Types – Cathode and Anode Definition
An electrode is a solid electric conductor usually metal that conducts electricity through nonmetallic materials, liquids, gases, plasmas, and vacuums.
Electrodes are the sites where oxidation and reduction occur.
There are two types of electrodes namely cathode and anode.
The definition of cathode and anode is given below:
Anode:
Anode is positively charged electrode. It is the site from which electron leaves and enter the electrolytic solution. Due to this, oxidation occurs at anode.
Cathode:
Cathode is negatively charged electrode to which electron enter from the electrolyte. Due to this reduction occur at cathode.
Electrodes are usually good conductors of electricity. They can be of metal or graphite.
Note: The the nature of electrode which will behave as a cathode or anode depends on the function performed by the cell.The direction in which a cell functions determines whether an electrode is a cathode or an anode.
For example, when a cell switches from acting galvanically (that is, producing energy like a battery) to electrolysis (that is, receiving energy), the cathode becomes the anode and vice versa.
Electrolyte Definition
An electrolyte is a substance that transmits electric current by dissociating into positively and negatively charged particles known as ions. These ions which migrate toward the electrodes of opposite nature i.e. cation being a positively charged particle will migrate towards the cathode which is of negative nature while an anion being negative in nature will get attracted towards anode which is positive in nature.
Electrolyte Example
Acids, bases, and salts are the most well-known electrolytes, which ionize when dissolved in water or alcohol. Salts when melted in the absence of any solvent for example such as sodium chloride, behave as electrolytes; some polymers are electrolytes even in the solid state.
Electroplating Process – Working
The working principle of Electroplating can be better understood by the following example:
Let’s take an example of a gold coating.
In this instance, a layer of gold is to be electrodeposited on metallic jewelry to enhance its appearance.
The gold plate is connected to the anode (positively charged electrode) of the circuit and the jewelry on which coating is to be done is kept at the cathode (negatively charged electrode).
Both are kept immersed in a highly developed electrolytic bath (solution) of gold.
At this stage, a power source is connected which creates a potential difference between the two electrodes, and current starts flowing from the anode which oxidizes the gold atoms from the anode and dissolves them into the solution.
These dissolved atoms later get reduced and get deposited on the jewelry connected to the cathode.
Thus by the above process, the jewelry gets a thin layer of gold on it which is chemically bonded and won’t be removed easily. However, continuous exposure of it to the atmosphere will degrade the layer.
Electric Current- Driving Force of Electroplating
Chemical reactions occur when an electric current passes through a conducting solution. This is called the chemical effect of electric current. The following are some of the chemical consequences of electric current:
Due to redox reaction, metal gets depleted from one electrode and deposited on other
Bubbles can form at the electrode due to the evolution of gas
Color of the solution can change due to displacement reaction.
Electroplating Process Examples
Here are some examples of electroplating :
Use Copper electrodes as an anode and Copper sulfate solution as an electrolyte. On the negative electrode, the metal will be copper electroplated. The addition of copper ions from the positive electrode replenishes the Cu in the solution.
To avoid corrosion or rusting, bathroom taps made of iron or steel are electroplated with chromium metal in which chromium is connected to an anode and chromium salt solution is used as an electrolyte.
Electrolysis Definition
Electrolysis is the decomposition of a chemical substance in a solution when an electric current is sent through it. The chemical action of electric current is responsible for this process.
Factors affecting Electroplating
These are the factors affecting elctroplating:
Current-Voltage level.
Electrolyte bath’s temperature and chemical makeup.
Amount of time that has passed.
Distance between the cathode and the anode is the distance between the cathode and the anode.
Electroplating Process – Types
Various types of Electroplating process are,
Chromium Plating
is the process of electroplating chromium onto a metal item.
Tin Plating
is the process of electroplating tin onto a metal item generally iron.
Nickel Plating
is the process of electroplating nickel onto a metal item.
Silver Plating
is the process of electroplating silver onto a metal item.
Gold Plating
is the process of electroplating gold onto a metal item.
Copper Plating
is the process of electroplating copper onto a metal item.
Electroplating – Advantages
The advantages of Electroplating are mentioned below:
Electroplating often reduce the friction of the metal surface
Electroplating protects the original metal by creating a barrier layer
Due to electroplating, adhesive properties of metal increases
Electroplating also adds to the thickness of the overall metal
Electroplating – Applications and Uses
Applications of Electroplating are :
To prevent rusting, metals are frequently coated with other metals.
Chromium plating is used on bath taps, automobile bumpers, and other similar items to give them a bright, appealing appearance while also resisting scratches and wear.
Silver plating is used for flatware and jewelry.
Tin cans are created by electroplating tin onto iron and are used to store food. Tin is a less reactive metal than iron. As a result, food does not come into touch with iron and is therefore protected against spoilage.
Conclusion
The process of electroplating is an important process in the fields of modern science and industry. This technique, which involves the deposition of a metal layer onto a substrate through the power of electric current, is not just about enhancing the appearance of objects. It plays a crucial role in extending their durability and resistance to corrosion. This article discussed the basic concepts of the electroplating process, its applications, definition, working principle, and types. We also learnt about the examples of the electroplating process, factors affecting it, its advantages and uses with diagram.
Electroplating – FAQs
1. What is Electroplating?
Electroplating is the hydrolysis-based plating of one metal onto another, most typically for ornamental purposes or to prevent metal corrosion. Copper plating, silver plating, and chromium plating are examples of specific forms of electroplating.
2. What are the applications of Electroplating?
Applications of Electroplating are:
Prevention of Rust
Chromium Plating of various objects such as bath taps, automobile bumpers, and others.
Silver Plating of Flatware and Jewelry.
Tin cans are created by electroplating Tin onto Iron.
3. What is Chromium Plating and how does it work?
The chromium plating process is an electroplating method for depositing a thin layer of chromium onto a substrate (metal or alloy).
Chromium Electroplating is accomplished by sending an eectric current between two electrodes immersed in a chromic acid electrolyte bath. The substrate to be coated will be cathode. Chromium atoms are deposited in a layer on the electrode to be plated during the flow of electricity between the two electrodes.
4. Which of Chromium’s Properties makes it suitable for Electroplating?
Chromium is a corrosive-resistant metal, but other metals, such as steel, corrode readily when exposed to damp air.
5. What are the benefits or advantages of Electroplating?
The following are some of the benefits of electroplating :
Corrosion resistance:a corrosion-prone substance, such as iron, can be protected by a coating of non-corrosive material.
Decorative items:otherwise dull surfaces can be given a gleam and sheen. This can be used as a decorative piece.
Less expensive decorations:instead of utilizing gold or silver, ornaments can be made out of less expensive metals and then electroplated with gold. This significantly lowers the cost of ornaments.
Improving mechanical properties:Electroplating can also help metals improve their mechanical properties.
6. What are the disadvantages of Electroplating?
The following are some of the disadvatages of electroplating :
Non-uniform plating:electroplating may or may not be uniform, resulting in a plated material with a poor appearance.
The technique is both expensive and time-consuming.
Pollution potential: after usage, the electroplating solution must be disposed of carefully, posing a threat to the environment.
7. What are the Factors affecting Electroplating?
Factors affecting electroplating are:
surface area of the electrodes,
temperature
kind of metal and
electrolyte utilized, and
amplitude of applied current
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