What is the insulation performance of bidirectional polyimide film
Bidirectional polyimide (PI) film is a high-performance insulation material with excellent insulation performance, which has a wide range of applications in the field of electrical and electronic engineering. The following provides a detailed analysis of its insulation performance characteristics from multiple dimensions:
Bidirectional polyimide (PI) film is a high-performance insulation material with excellent insulation performance, which has a wide range of applications in the field of electrical and electronic engineering. The following provides a detailed analysis of its insulation performance characteristics from multiple dimensions:
1、 Core insulation performance indicators
1. Breakdown field strength (electrical strength)
The breakdown field strength of bidirectional PI film is usually between 200~400 kV/mm (the specific value depends on the film thickness and testing conditions), significantly higher than most organic insulation materials (such as polyester film about 100~200 kV/mm).
Even in high-frequency and high-voltage environments, it can maintain stable insulation strength and is suitable for insulation layers of high-voltage equipment such as motors, cables, and transformers.
2. Volume resistivity and surface resistivity
Volume resistivity: ≥ 10 1?Ω· cm, almost non-conductive, can effectively prevent current from passing through the interior of the material.
Surface resistivity: ≥ 10 1? Ω, not easily caused by surface pollution or moisture, suitable for harsh environments such as humidity and dust.
3. Dielectric constant and dielectric loss
At a frequency of 1MHz, the dielectric constant is approximately 3.0~3.5 (low dielectric properties are beneficial for reducing signal transmission losses).
The tangent value of dielectric loss angle (tan δ) ≤ 0.005 indicates that the material has low energy loss in high-frequency electric fields and is suitable for high-frequency electronic devices (such as 5G communication and microwave components).
2、 Environmental adaptability of insulation performance
1. High temperature resistance and low temperature stability
The working temperature range is wide (-269 ℃~+260 ℃), and the insulation performance can still be maintained without significant decrease at high temperatures (such as above 200 ℃), while insulation failure will not occur due to embrittlement in low temperature environments, making it suitable for extreme temperature scenarios (such as aerospace and deep-sea equipment).
2. Chemical corrosion resistance and radiation resistance
Acid resistant, alkaline, organic solvent and other chemical media corrode, and the insulation layer is not easily damaged by electrolytes, lubricants and other substances.
Strong resistance to radiation such as gamma rays and X-rays, and able to maintain insulation performance in the nuclear industry and space environment, superior to ordinary plastic films.
3. Moisture resistance and arc resistance
Low water absorption rate (<1%), small decrease in volume resistivity in humid environments, and less likely to cause insulation breakdown due to moisture.
The arc resistance is ≥ 180 seconds (i.e. the time it takes for the material surface to form a conductive channel under the action of an arc), which can reduce the damage of high-voltage discharge to the insulation layer.
3、 The influence of structure and process on insulation performance
1. Advantages of Bi directional Stretching Process
Through biaxial stretching (transverse and longitudinal), the molecular chain arrangement of the thin film is more regular, the crystallinity is improved, and internal defects (such as pores and impurities) are reduced, thereby further improving the breakdown field strength and size stability, and avoiding insulation weak points caused by stress concentration.
2. Uniformity of film thickness
The thickness tolerance of high-quality bidirectional PI film can be controlled within ± 1%, and the uniformity of thickness directly affects the distribution of electric field, avoiding local high field strength that may cause breakdown. It is suitable for thin layer insulation of precision electronic devices.
3. Typical application scenarios
Motors and transformers: As slot insulation and turn insulation materials, they can withstand high voltage and high temperature environments (such as new energy vehicle drive motors and dry-type transformers).
Flexible Circuit Board (FPC): Used as an insulating substrate to meet the reliability requirements for high-frequency signal transmission and bending.
Cable and wire: insulation layer of high-voltage cable or coating material of high-temperature resistant wire.
Aerospace and Military Industry: Insulation components for satellite electronic equipment and rocket engines, suitable for extreme temperature and radiation environments.
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