What is the insulation performance of unidirectional polyimide film
Unidirectional polyimide film is a special polymer film material with high insulation level and stable insulation performance. Its insulation performance is derived from the molecular structure characteristics of polyimide (PI) itself, as well as the directional mechanical and electrical advantages endowed by unidirectional processes. It is widely used in fields with strict insulation requirements
Unidirectional polyimide film is a special polymer film material with high insulation level and stable insulation performance. Its insulation performance is derived from the molecular structure characteristics of polyimide (PI) itself, as well as the directional mechanical and electrical advantages endowed by unidirectional processes. It is widely used in fields with strict insulation requirements such as aerospace, new energy vehicles, and electronic equipment. The specific insulation performance characteristics are as follows:
1. High breakdown field strength and excellent insulation withstand voltage capability
The breakdown field strength of unidirectional polyimide film can usually reach 20-35 kV/mm, far exceeding that of ordinary polyester (PET) film (about 15-20 kV/mm) and epoxy film. This characteristic enables it to withstand strong electric field impacts in high-voltage circuits without being broken down. For example, in scenarios such as new energy vehicle motor windings and high-voltage inverter insulation layers, it can effectively block current leakage and ensure stable operation of equipment under high voltage conditions. At the same time, the uniaxial stretching process aligns the molecular chains of the film along the stretching direction, reducing internal defects and impurity aggregation, further improving the uniformity of breakdown voltage, and reducing the risk of partial discharge.
2. High volume resistivity and surface resistivity
The volume resistivity of this film can reach 10 1?～ 10 1?Ω· cm, and the surface resistivity exceeds 10 1? Ω, belonging to the category of super insulating materials. High volume resistivity means that it is difficult for current to form a conduction path inside the film, while high surface resistivity can prevent surface leakage, especially suitable for insulation protection in complex environments such as humidity and dust. Even under high temperature or high humidity conditions, the decrease in resistivity is much smaller than that of traditional insulation materials, indicating significant insulation stability.
3. Outstanding high-temperature insulation characteristics and strong temperature adaptability
Polyimide itself is a high-temperature resistant polymer material, with long-term use temperatures ranging from -200 ℃ to 260 ℃, and short-term temperature tolerance even exceeding 400 ℃. Unidirectional polyimide film inherits this advantage and does not exhibit softening, carbonization, or brittle cracking in extreme high and low temperature environments. Its insulation performance is almost unaffected by temperature fluctuations. For example, in scenarios such as aircraft engine cable insulation and satellite electronic component packaging, reliable insulation can be maintained continuously in high and low temperature alternating environments, solving the pain point of high-temperature failure of traditional insulation materials.
4. Chemical corrosion resistance, insulation performance not affected by the medium
Unidirectional polyimide film has excellent chemical stability and good resistance to corrosive media such as acid, alkali, and organic solvents. It will not swell, degrade, or deteriorate its insulation performance due to contact with chemicals. This feature makes it suitable for insulation protection in corrosive environments such as chemical equipment and marine equipment, and it can also withstand long-term immersion of insulation media such as transformer oil and insulation paint, with good compatibility with various insulation systems.
5. Directional consistency and process adaptability of insulation performance
The uniaxial stretching process results in directional consistency in the insulation performance of the film, with insulation strength slightly higher along the stretching direction than in the transverse direction. This characteristic can be designed specifically for practical application scenarios. For example, in the insulation of motor windings, the stretching direction of the film can be perpendicular to the direction of the electric field to enhance its voltage resistance performance; In flexible circuit board (FPC) substrates, directional insulation properties can enhance the anti-interference ability between circuit layers and reduce signal transmission losses.
It should be noted that the insulation performance of unidirectional polyimide films is affected by factors such as film thickness and surface cleanliness. The thicker the film, the higher the breakdown voltage, but it is necessary to balance insulation requirements with product lightweighting requirements; At the same time, it is necessary to avoid scratching the surface of the film or adhering impurities during use to prevent the formation of partial discharge channels, which may affect insulation reliability.
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