Aramid materials are widely used in the fields of electrical insulation and electronics due to their high-performance material properties.
1. Application direction of aramid in electrical insulation and electronics
1.1 Transformer
The use of aramid fiber is undoubtedly an ideal material for the core wire, interlayer and interphase insulation of the transformer. It has obvious advantages in the application process, and the oxygen limit index of fiber paper is >28, so it is a good flame-retardant material. At the same time, the heat resistance reaches 220 level, which can reduce the cooling space of the transformer, promote compact internal structure, reduce the loss when the transformer is no-load, and reduce the manufacturing cost.
Because of its good insulation effect, it can improve the ability of the transformer to store temperature and harmonic load, so it has an important application in transformer insulation. In addition, the material has good moisture resistance and can be used in humid environments.
1.2 Motor
In the motor manufacturing process, aramid fiber is widely used. Fiber and cardboard together form the insulation system of the motor product, so that the product can run under overload. Due to the small size and good performance of the material, it can not be damaged during the coil winding process.
Its application methods include insulation between phases, lead wires, ground, wires, and groove linings. For example, fiber paper with a thickness of 0.18mm~0.38mm has good flexibility and is suitable for slot liner insulation; the thickness of 0.51mm~0.76mm has a higher built-in hardness, so it can be used in slot wedge positions.
1.3 Circuit board
After the application of aramid fiber in the circuit board, the electrical strength, point resistance, and laser speed are greater, and the ion can be processed higher, and the ion density is lower. Due to the above advantages, it is widely used in the electronic field.
In the 1990s of the 20th century, circuit boards made of aramid materials became the focus of social attention of SMT substrate materials, and aramid fibers were widely used in circuit board substrates and other aspects.
1.4 Radar antenna
In the rapid development of satellite communications, radar antennas are required to have the advantages of small mass, lightness, and strong reliability.
Aramid fiber has high stability in performance, good electrical insulation, and strong wave permeability and mechanical properties, so it can be used in the field of radar antennas. For example: It can be reasonably used in structures such as overhead antennas, naval vessels and aircraft radomes, and radar feeders.
2. Specific applications of aramid in electrical insulation and electronics
2.1 Application in various transformers
Aramid fiber can be used in dry-type transformers. Aramid fiber is used in the winding point of the coil to effectively increase the temperature index of the transformer insulation system and extend its service life.
A high-temperature resistant insulation system composed of fiber paper and high-temperature oil is used in railway traction equipment and power distribution equipment to reduce the mass and volume of transformers.
In high-speed trains, aramid materials are used to form the insulation system of the transformer, which reduces the volume of the transformer to 80%~85% of the original, reduces the workload of fault maintenance, and improves the safety performance of the transformer.
Make full use of the advantages of aramid fiber and apply it in transformers as the main insulation material to ensure structural safety.
Aramid fiber can be used in oil-immersed transformers, combined with beta oil with a higher ignition point, to produce a transformer with a high ignition point.
This type of transformer has low operating cost and good fire resistance. For example, using aramid fiber and silicone oil to make a 150kVA transformer, the quality is not much different from that of a 100kVA transformer.
2.2 Application in various types of motors
Aramid fiber can be used in the insulation system of special motors. The application of aramid fiber in variable frequency speed control motors and 2500kV AC variable frequency motors has good insulation properties.
At the same time, the use of aramid fiber made of epoxy resin composite material as the rotor protection ring of the engine can effectively solve the problem of the weak performance of the traditional glass fiber latitude belt.
Under normal conditions, the tensile strength of the sample is 1816MPa, so it can meet the requirements of a highly operating environment.
In addition, aramid fiber can also be used as structural insulation between motor turns, which can reduce the thickness of the insulating layer, while reducing the temperature rise speed of the motor, and improving the overall performance of the motor.
Aramid fiber can also be used in generators. After the fiber paper is soaked in epoxy resin, it is placed in the rotor coil to form an insulating structure, which improves the mechanical strength of the coil and shortens the manufacturing cycle of the generator.
Researchers conducted research on the Dongfang generator used in the Three Gorges unit and found that the unit uses aramid material as winding insulation, which not only meets the technical insulation requirements of the unit, but also can be used in large or medium-sized hydroelectric generators. .
In addition, aramid fiber can also be used in the grounding insulation of the motor to avoid the problem of abnormal shutdown of the motor. Using aramid fiber and polyimide to form a composite material to form a closed lead, the inner and outer layers are woven with aramid fiber, which can make the motor have good insulation performance under the conditions of lubricating oil and refrigerant.
2.3 Application in printed circuit boards
The manufacturing process of the printed circuit board (hereinafter referred to as PCB) uses aramid fiber to synthesize a high-density electronic chip lead support. This type of support has strong tensile properties, so it can avoid the copper sheet and the resin matrix after being heated. There is a problem of separation between.
In the electronics industry, the use of aramid materials to make PCB boards can enhance the strength and quality of the circuit boards. The size of this circuit board is excellent, and the expansion coefficient is 3×10-6/℃. Due to the low dielectric constant of the circuit board, it is suitable for high-speed transmission of lines.
Compared with the glass fiber material, the quality of this circuit board is reduced by 20%, thus achieving the manufacturing goal of light weight and small system of electronic equipment.
A Japanese company has developed a PCB board with better stability, higher flexibility, and stronger moisture resistance. In the manufacturing process, aramid fiber is used in the meta position to accelerate the preparation of epoxy-based resin materials. Compared with the application of counterpoint materials, it is easier to process and has better moisture absorption performance.
The PCB made of aramid fiber has light weight and strong performance, and can be used in smart phones and tablet computers.
In addition, the current circuit boards made of aramid fibers based on the multilayer structure can encapsulate high-density electronics, which are suitable for application in the high-speed transmission process of circuits and have been widely used in the military industry.
2.4 Application in antenna components
As the aramid material has good dielectric properties, it is used in radome components, which is thinner than traditional glass radomes, has good rigidity and higher signal transmittance.
Compared with the half-wavelength type radome, the radome in the sandwich position uses the aramid material to make the honeycomb sandwich. The core material is lighter and the strength is higher than that of the glass core material. The disadvantage is the cost of manufacturing. Higher.
Therefore, it can only be used in the manufacture of radome components in high-end fields such as shipborne radar and airborne radar.
The American company and Japan jointly developed a radar parabolic antenna, using para-aramid material on the radar reflecting surface.
2.5 Applications in other fields
In addition to the applications in the above fields, aramid fibers are also widely used in the fields of electronic components such as composite membranes, insulating ropes/rods, circuit breakers, and brakes.
For example: In a 500kV transmission line, using insulated ropes made of aramid materials instead of insulated hangers as load-bearing tools, and using insulated ropes to connect the threaded rods is conducive to promoting a safety factor of 3 or more.
The insulating rod is mainly a structure composed of aramid fiber and polyester fiber entangled with each other, placed in a vacuum, and immersed in an epoxy resin material, and then cured.
During use, it has good corrosion resistance, light weight and higher strength. This material has good insulation properties.
In the 110kV line, the operation of using the insulating rod is more frequent, and the mechanical strength is high during the application process, and it has good dynamic fatigue resistance characteristics.
In the manufacture of electrical machinery, the use of aramid fiber materials can increase the strength of components and prevent serious wear on the surface of the molding replacement. It replaces glass fibers in electrical equipment. The fiber content of aramid fibers is 5% and the length can reach 6.4mm. The tensile strength is 28.5MPa, the arc resistance is 192s, and the impact strength is 138.68J/m, so the abrasion resistance is higher.