Copper foil is a thin sheet of copper metal that is widely used in various applications due to its excellent electrical conductivity, malleability, and corrosion resistance. It is an essential material in the electronics industry, especially for manufacturing printed circuit boards (PCBs) and other electronic components. Copper foil is produced through a meticulous manufacturing process, ensuring its quality and performance in various applications. [1]
The manufacturing of copper foil involves several steps, including casting, rolling, annealing, and finishing. The process starts with molten copper being cast into large slabs, which are then rolled down to the desired thickness. During the rolling process, the copper undergoes annealing, a heat treatment that improves its flexibility and removes any internal stresses.
Once the copper reaches the desired thickness, it is further processed to achieve specific surface qualities, such as matte, half-matte, or shiny finishes. The finished copper foil is then spooled into rolls of varying widths and lengths, depending on the intended application. [2]
Copper foil is available in different types to suit various applications. The most common types include: [3] [4]
Electrodeposited copper foil, also known as electrolytic copper foil, is produced by electroplating copper onto a rolling drum in a highly controlled manner. This type of copper foil has uniform thickness and excellent electrical conductivity, making it ideal for high-performance electronic applications.
Rolled Annealed copper foil is produced through a rolling and annealing process, as described earlier. It offers good flexibility and is commonly used in flexible printed circuit boards (PCBs) and other applications where flexibility is required.
High-Temperature Rolled Annealed copper foil is similar to RA copper foil but undergoes additional heat treatment to enhance its resistance to high temperatures. This type of copper foil is used in applications that involve exposure to elevated temperatures.
Ultra-thin copper foil is an extremely thin variant used in specialized applications where space is limited, such as in RFID tags and smart cards.
Copper foil has a wide range of applications, with its primary use being in the electronics industry. Some of the major applications include: [5]
Copper foil is a crucial component in the manufacturing of PCBs, which are the building blocks of electronic devices. It is used to create conductive traces and interconnections on the insulating substrate, allowing the flow of electrical signals between different components.
Copper foil is utilized in lithium-ion batteries as a current collector. It enhances the battery's performance by providing a conductive pathway for the flow of electrons during charging and discharging processes.
Due to its high electrical conductivity, copper foil is employed for electromagnetic shielding in various electronic devices. It helps prevent electromagnetic interference (EMI) and radio frequency interference (RFI), ensuring proper device operation.
In artistic applications, copper foil is used in stained glass artwork to join individual glass pieces together, providing structural support and creating decorative elements.
Copper foil is utilized in the winding of electrical transformers due to its low electrical resistance, ensuring efficient power transmission and minimizing energy loss.
Organic electronics is a field of materials science concerning the design, synthesis, characterization, and application of organic molecules or polymers that show desirable electronic properties such as conductivity. Unlike conventional inorganic conductors and semiconductors, organic electronic materials are constructed from organic (carbon-based) molecules or polymers using synthetic strategies developed in the context of organic chemistry and polymer chemistry.
A wire is a flexible strand of metal.
Electroplating, also known as electrochemical deposition or electrodeposition, is a process for producing a metal coating on a solid substrate through the reduction of cations of that metal by means of a direct electric current. The part to be coated acts as the cathode of an electrolytic cell; the electrolyte is a solution of a salt of the metal to be coated; and the anode is usually either a block of that metal, or of some inert conductive material. The current is provided by an external power supply.
A printed circuit board (PCB), also called printed wiring board (PWB), is a medium used to connect or "wire" components to one another in a circuit. It takes the form of a laminated sandwich structure of conductive and insulating layers: each of the conductive layers is designed with an artwork pattern of traces, planes and other features etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate. Electrical components may be fixed to conductive pads on the outer layers in the shape designed to accept the component's terminals, generally by means of soldering, to both electrically connect and mechanically fasten them to it. Another manufacturing process adds vias: plated-through holes that allow interconnections between layers.
Flexible electronics, also known as flex circuits, is a technology for assembling electronic circuits by mounting electronic devices on flexible plastic substrates, such as polyimide, PEEK or transparent conductive polyester film. Additionally, flex circuits can be screen printed silver circuits on polyester. Flexible electronic assemblies may be manufactured using identical components used for rigid printed circuit boards, allowing the board to conform to a desired shape, or to flex during its use.
FR-4 is a NEMA grade designation for glass-reinforced epoxy laminate material. FR-4 is a composite material composed of woven fiberglass cloth with an epoxy resin binder that is flame resistant (self-extinguishing).
Gold plating is a method of depositing a thin layer of gold onto the surface of another metal, most often copper or silver, by chemical or electrochemical plating. This article covers plating methods used in the modern electronics industry; for more traditional methods, often used for much larger objects, see gilding.
The role of the substrate in power electronics is to provide the interconnections to form an electric circuit, and to cool the components. Compared to materials and techniques used in lower power microelectronics, these substrates must carry higher currents and provide a higher voltage isolation. They also must operate over a wide temperature range.
Conformal coating is a protective, breathable coating of thin polymeric film applied to printed circuit boards (PCB). It is named as such because it conforms to the contours of the PCB. Conformal coatings are typically applied at 25–250 μm to the electronic circuitry and provide protection against moisture, dust, chemicals, and temperature extremities. More recently, conformal coatings are being used to reduce the formation of whiskers, and can also prevent current bleed between closely positioned components.
Flat no-leads packages such as quad-flat no-leads (QFN) and dual-flat no-leads (DFN) physically and electrically connect integrated circuits to printed circuit boards. Flat no-leads, also known as micro leadframe (MLF) and SON, is a surface-mount technology, one of several package technologies that connect ICs to the surfaces of PCBs without through-holes. Flat no-lead is a near chip scale plastic encapsulated package made with a planar copper lead frame substrate. Perimeter lands on the package bottom provide electrical connections to the PCB. Flat no-lead packages usually, but not always, include an exposed thermally conductive pad to improve heat transfer out of the IC. Heat transfer can be further facilitated by metal vias in the thermal pad. The QFN package is similar to the quad-flat package (QFP), and a ball grid array (BGA).
Magnet wire or enameled wire is a copper (Cu) or aluminium (Al) wire coated with a very thin layer of insulation. It is used in the construction of transformers, inductors, motors, generators, speakers, hard disk head actuators, electromagnets, electric guitar pickups, and other applications that require tight coils of insulated wire.
Printed electronics is a set of printing methods used to create electrical devices on various substrates. Printing typically uses common printing equipment suitable for defining patterns on material, such as screen printing, flexography, gravure, offset lithography, and inkjet. By electronic-industry standards, these are low-cost processes. Electrically functional electronic or optical inks are deposited on the substrate, creating active or passive devices, such as thin film transistors; capacitors; coils; resistors. Some researchers expect printed electronics to facilitate widespread, very low-cost, low-performance electronics for applications such as flexible displays, smart labels, decorative and animated posters, and active clothing that do not require high performance.
IPC is a trade association whose aim is to standardize the assembly and production requirements of electronic equipment and assemblies. It was founded in 1957 as the Institute of Printed Circuits. Its name was later changed to the Institute for Interconnecting and Packaging Electronic Circuits to highlight the expansion from bare boards to packaging and electronic assemblies. In 1999, the organization formally changed its name to IPC with the accompanying tagline, Association Connecting Electronics Industries.
The thin film lithium-ion battery is a form of solid-state battery. Its development is motivated by the prospect of combining the advantages of solid-state batteries with the advantages of thin-film manufacturing processes.
Soldering is a process of joining two metal surfaces together using a filler metal called solder. The soldering process involves heating the surfaces to be joined and melting the solder, which is then allowed to cool and solidify, creating a strong and durable joint.
Copper has been used in electrical wiring since the invention of the electromagnet and the telegraph in the 1820s. The invention of the telephone in 1876 created further demand for copper wire as an electrical conductor.
An electrically conductive adhesive is a glue that is primarily used for electronics.
Annealed Pyrolytic Graphite (APG), also known as Thermally Annealed Pyrolytic Graphite (TPG), is a form of synthetic graphite that offers excellent in-plane thermal conductivity. As with pyrolytic carbon or pyrolytic graphite (PG), APG is also low in mass, is electrically conductive, and offers diamagnetic properties that allow it to levitate in magnetic fields.
Lithium aluminium germanium phosphate, typically known with the acronyms LAGP or LAGPO, is an inorganic ceramic solid material whose general formula is Li
1+xAl
xGe
2-x(PO
4)
3. LAGP belongs to the NASICON family of solid conductors and has been applied as a solid electrolyte in all-solid-state lithium-ion batteries. Typical values of ionic conductivity in LAGP at room temperature are in the range of 10–5 - 10–4 S/cm, even if the actual value of conductivity is strongly affected by stoichiometry, microstructure, and synthesis conditions. Compared to lithium aluminium titanium phosphate (LATP), which is another phosphate-based lithium solid conductor, the absence of titanium in LAGP improves its stability towards lithium metal. In addition, phosphate-based solid electrolytes have superior stability against moisture and oxygen compared to sulfide-based electrolytes like Li
10GeP
2S
12 (LGPS) and can be handled safely in air, thus simplifying the manufacture process. Since the best performances are encountered when the stoichiometric value of x is 0.5, the acronym LAGP usually indicates the particular composition of Li
1.5Al
0.5Ge
1.5(PO
4)
3, which is also the typically used material in battery applications.