Why use copper? What are its main properties?
Copper has excellent electrical and thermal conductivity, ranking first among all engineering metal materials. This is the main basis for its pivotal role in the current electrification and electronic information society. Copper also has many excellent comprehensive properties: it has strong corrosion resistance to the atmosphere, seawater, soil and many chemical media; it is used in the structure to be both rigid and flexible, elastic, friction-resistant and wear-resistant; it has a colorful appearance and is a symbol of simplicity and elegance that people love. In addition to the above-mentioned numerous performance properties, it also has a series of good processing, casting, welding, easy cutting and other process properties, which makes it economical and widely used.
-Housing construction accounts for 48%: including: pipeline systems (water, heat, gas, fire sprinklers, etc.); housing facilities (air conditioners, refrigerators, etc.); building decoration (roofs, troughs, decorations, etc.); communication lines (sound, image, data, etc.); power supply systems.
--Equipment production accounts for 41%: including: industrial equipment (motors, transformers, etc.); transportation tools (automobiles, railways, airplanes, etc.); electronic devices; light industrial products (household appliances, instruments, tools, etc.)
--Infrastructure accounts for 11%: including: large-scale projects (transportation facilities, petrochemical industry, mining and metallurgy industry, etc.); power industry (power transmission, power distribution, etc.); communication network.
It is worth noting that housing construction is directly related to the improvement of people's production level, and the application of copper in this regard accounts for the largest proportion; especially my country regards residential construction as an important link to drive the development of the entire national economy. It can be seen that actively promoting the application of copper plays an important role in the national economy and people's livelihood.
A. Application in the electrical industry
※ Power transmission
A large amount of highly conductive copper is consumed in power transmission, mainly used for power, wires and cables, buses, transformers, switches, plug-in components and connectors, etc.
In the transmission process of wires and cables, electric energy is wasted due to resistance heating. From the perspective of energy saving and economy, the "optimal cable cross-section" standard is currently being promoted in the world. The "optimal cable cross-section" standard takes into account both the one-time installation cost and the power consumption, and appropriately enlarges the cable size to achieve energy saving and the best comprehensive economic benefits. According to the new standard, the cable cross-section is often more than doubled than the old standard, which can achieve an energy saving effect of about 50%.
In the past period of time, due to the shortage of steel in my country, considering that the specific gravity of aluminum is only 30% of copper, measures have been taken to replace copper with aluminum in overhead high-voltage transmission lines in the hope of reducing weight. At present, from the perspective of environmental protection, aerial transmission lines will be converted to laying underground cables. In this case, aluminum has the disadvantages of poor conductivity and larger cable size compared with copper, and it pales in comparison.
For the same reason, it is also a wise choice to replace aluminum winding transformers in the United States and Japan with energy-saving and efficient copper winding transformers.
※ Motor manufacturing
In motor manufacturing, high-conductivity and high-strength copper alloys are widely used. The main copper parts are stators, rotors, and shaft heads. In large motors, the windings are cooled with water or hydrogen, which is called double water internal cooling or hydrogen cooling motors, which requires long hollow wires.
Motors are large users of electricity, accounting for about 60% of the total electricity supply. The cumulative electricity bill for a motor is very high. Generally, it reaches the cost of the motor itself within the first 500 hours of operation, which is equivalent to 4 to 16 times the cost within a year, and can reach 200 times the cost during the entire working life. A small increase in motor efficiency can not only save energy, but also obtain significant economic benefits. The development and application of high-efficiency motors is a hot topic in the world today. Since the energy consumption inside the motor mainly comes from the resistance loss of the winding; therefore, increasing the cross-section of copper wire is a key measure to develop high-efficiency motors. In recent years, some high-efficiency motors that have been developed first have increased the use of copper windings by 25% to 100% compared with traditional motors. At present, the US Department of Energy is funding a development project to use cast copper technology to produce motor rotors.
※ Communication cables
Since the 1980s, due to the advantages of large current carrying capacity of optical fiber cables, they have been continuously replacing copper cables on communication trunk lines and have been rapidly promoted and applied. However, a large amount of copper is still needed to convert electrical energy into light energy and to input the lines to users. With the development of the communications industry, people are increasingly dependent on communications, and the demand for optical fiber cables and copper wires will continue to increase.
※ Residential electrical lines
In recent years, with the improvement of people's living standards in my country, household appliances have been rapidly popularized, and the residential electricity load has grown rapidly. my country's residential electricity consumption will still have great development in the future, which has greatly increased the application of copper wires.
B. Application in the electronics industry
The electronics industry is an emerging industry. In its thriving development process, new products and new application areas of steel are constantly being developed. At present, its application has developed from vacuum devices and printed circuits to microelectronics and semiconductor integrated circuits.
※ Vacuum devices
Vacuum devices are mainly high-frequency and ultra-high-frequency transmitting tubes, waveguides, magnetrons, etc., which require high-purity oxygen-free copper and dispersion-strengthened oxygen-free copper.
※ Printed circuits
Copper printed circuits are made by pasting copper foil on a plastic plate as a support with copper foil as the surface; printing the circuit wiring diagram on the copper plate by photographing; removing the excess parts by etching and leaving the interconnected circuits. Then, punch holes at the connection with the outside on the printed circuit board, insert the terminals of the discrete components or other parts, and weld them on this opening, so that a complete circuit is assembled. If the immersion plating method is used, the welding of all the joints can be completed at one time. In this way, for those occasions that require fine layout of circuits, such as radio, television, computer, etc., the use of printed circuits can save a lot of labor in wiring and fixing circuits; therefore, it is widely used and requires a large amount of copper foil. In addition, various copper-based brazing materials with low prices, low melting points and good fluidity are also required in the connection of circuits.
※ Integrated Circuit
The core of microelectronics technology is the integrated circuit. Integrated circuit refers to a miniaturized circuit that uses semiconductor crystal materials as substrates (chips) and uses special process technologies to integrate the components and interconnects that make up the circuit inside, on the surface or on the substrate. This microcircuit is thousands of times smaller in size and weight than the most compact discrete component circuit in structure. Its appearance has caused a huge change in computers and has become the foundation of modern information technology. The ultra-large-scale integrated circuits that have been developed so far have a number of transistors that can be made on a single chip area smaller than a thumb nail, reaching hundreds of thousands or even millions. Recently, IBM (International Business Machines Corporation), a world-renowned computer company, has made a breakthrough by using copper to replace aluminum in silicon chips as interconnects. This new type of copper microchip can achieve a 30% performance gain, the circuit line size can be reduced to 0.12 microns, and the number of transistors integrated on a single chip can reach 2 million. This has opened up a new situation for the application of the ancient metal copper in the latest technology field of semiconductor integrated circuits.
※ Lead frame
In order to protect the normal operation of integrated circuits or hybrid circuits, it is necessary to package them; and when packaging, a large number of connectors in the circuit are led out of the sealed body. These leads are required to have a certain strength and constitute the supporting skeleton of the integrated package circuit, which is called a lead frame. In actual production, for high-speed and mass production, lead frames are usually continuously stamped on a metal strip in a specific arrangement. The frame material accounts for 1/3 to 1/4 of the total cost of the integrated circuit, and the amount used is large; therefore, it must have a low cost.
Copper alloy is cheap, has high strength, electrical conductivity and thermal conductivity, excellent processing performance, needle welding and corrosion resistance. Its performance can be controlled in a wide range through alloying, and can better meet the performance requirements of lead frames. It has become an important material for lead frames. It is currently the most used material in microelectronic devices.
