What are the applications of unidirectional polyimide film in the electrical industry
Unidirectional polyimide film (PI film) is a high-performance polymer material with high temperature resistance, chemical corrosion resistance, excellent electrical insulation, and high mechanical strength. It is widely used in the electrical industry for scenarios that require high reliability and extreme environmental resistance. The following are its core application areas and specific scenario
Unidirectional polyimide film (PI film) is a high-performance polymer material with high temperature resistance, chemical corrosion resistance, excellent electrical insulation, and high mechanical strength. It is widely used in the electrical industry for scenarios that require high reliability and extreme environmental resistance. The following are its core application areas and specific scenarios:
1、 In the field of motors and generators
1. High temperature resistant insulation material
Application scenarios:
Motors that operate in high-temperature environments such as high-speed motors, aerospace motors, new energy vehicle drive motors, and industrial servo motors.
The slot insulation, phase insulation, and interlayer insulation of the stator and rotor of the generator.
Core advantages:
High temperature resistance level: Long term use temperature up to 220 ℃ (in accordance with UL certified Class H standard), short-term can withstand high temperatures above 300 ℃, far exceeding ordinary polyester film (temperature resistance of 130-150 ℃).
Excellent mechanical strength: Unidirectional stretching process enhances the longitudinal strength of the film (tensile strength can reach 150-200MPa), which can withstand the mechanical stress during motor winding and avoid insulation layer damage.
Typical case:
In the drive motor of new energy vehicles, PI film is used for insulation wrapping of the stator winding to ensure stable operation of the motor at high speeds (>15000rpm) and high temperatures (winding temperature can reach 180 ℃).
2. Solution for corona resistant insulation
Application scenarios:
The corona resistant insulation layer of variable frequency motors and high-frequency motors (such as wind power inverter driven motors).
Technical features:
By using nanocomposite technology (such as adding ceramic fillers) to produce corona resistant PI films, they can withstand partial discharge erosion caused by high-frequency pulse voltage (rising edge<100ns) and have a lifespan 5-10 times longer than ordinary PI films.
Used for inter turn insulation of motors to prevent insulation breakdown caused by corona discharge and improve the reliability of motors under variable frequency conditions.
2、 Wire and Cable, Flexible Circuit Board (FPC)
1. Insulation of high-temperature resistant wires
Application scenarios:
Aerospace wiring (such as aircraft engine wiring harness), industrial high-temperature sensor cables, electric vehicle battery wiring harness.
Performance advantages:
Chemical corrosion resistance: resistant to chemical media such as lubricating oil, hydraulic oil, fuel, etc., suitable for complex environments such as engine compartments.
Ultra thin and flexible: The thickness can be as low as 12.5 μ m, meeting the miniaturization requirements of precision wire harnesses, while supporting complex curved wiring.
Typical products:
PI thin film insulated wire certified by the US military standard M16878, used for wiring in high-temperature areas of aviation electronic equipment.
2. Flexible Circuit Board (FPC) substrate
Application scenarios:
Flexible circuit board substrates for consumer electronics (mobile phones, wearable devices), such as camera module cables, foldable screen mobile phone hinge connection circuits.
Automotive electronics (dashboard FPC, onboard radar wiring harness).
Key features:
Bending resistance: Unidirectional PI film has excellent tear resistance in the longitudinal direction and can withstand more than 100000 bending cycles (curvature radius<1mm), meeting the dynamic performance requirements of foldable equipment.
Low dielectric constant (ε ≈ 3.5): Suitable for high-frequency signal transmission, such as FPC substrates for 5G antenna modules.
3、 Electronic Devices and Integrated Circuits
1. Insulation layer of chip packaging substrate
Application scenarios:
The insulation layer of semiconductor packaging substrates (such as BGA, QFP packaging) is used for electrical isolation between chips and pins.
Technical value:
Good thermal compatibility: The coefficient of thermal expansion (CTE) is about 20-30 ppm/℃, compatible with silicon chips (CTE ≈ 3ppm/℃) and copper pins (CTE ≈ 17ppm/℃), reducing cracking caused by thermal cycling stress.
High insulation reliability: Volume resistivity>10 ¹⁴Ω· cm, dielectric strength>100kV/mm, ensuring the insulation safety of the chip in high-voltage environments.
2. Protection of high-temperature electronic components
Application scenarios:
Insulation pads for power devices (IGBT, MOSFET) and cladding materials for high-temperature sensors (such as thermocouples).
Functional advantages:
Isolate high-voltage devices from metal heat sinks, while withstanding high temperatures during device operation (such as IGBT junction temperature up to 175 ℃).
Excellent radiation resistance (able to withstand a dose of 10 ⁶ Gy), suitable for electronic component protection in extreme environments such as nuclear energy equipment and space probes.
4、 In the field of new energy and energy storage
1. Insulation and thermal management of lithium batteries
Application scenarios:
Ear insulation tape and cell spacing heat pad for power batteries (such as square aluminum shell batteries and soft pack batteries).
Innovative applications:
Coated PI film: The surface is coated with ceramic coating or silicone, which combines insulation and thermal conductivity (thermal conductivity coefficient 0.5-1.0W/m · K), used for designing the thermal conduction path between battery cells, and improving the heat dissipation uniformity of the battery pack.
Corrosion resistance of electrolyte: Resist the corrosion of lithium hexafluorophosphate (LiPF ₆) electrolyte and avoid the risk of short circuit caused by swelling and damage of traditional PET films.
2. Proton exchange membrane support for fuel cells
Potential applications:
The enhanced support layer of proton exchange membrane (PEM) in hydrogen fuel cells utilizes the mechanical strength of PI film to improve the puncture resistance of membrane electrode (MEA).
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