What are the advantages of unidirectional polyimide film
Unidirectional Polyimide Film, abbreviated as Unidirectional PI Film, is a functional film in which polyimide (PI) molecular chains are highly oriented in a single direction through a special process. Its core advantages revolve around "oriented high strength, high temperature stability, excellent dielectric properties, and lightweight adaptation", especially suitable for fields with rigid require
Unidirectional Polyimide Film, abbreviated as Unidirectional PI Film, is a functional film in which polyimide (PI) molecular chains are highly oriented in a single direction through a special process. Its core advantages revolve around "oriented high strength, high temperature stability, excellent dielectric properties, and lightweight adaptation", especially suitable for fields with rigid requirements such as "directional mechanical support, extreme environmental resistance, and insulation protection". The specific advantages are as follows:
1、 Core advantages: Outstanding directional mechanical performance, suitable for "unidirectional force" scenarios
The key advantage of unidirectional PI film is the "directional concentration of mechanical properties" - molecular chains are arranged in a single direction, which gives the film strength and rigidity far exceeding that of ordinary PI film in the orientation direction (longitudinal), while maintaining moderate toughness in the non orientation direction (transverse), suitable for scenarios that only require unidirectional force support:
High directional tensile strength: The tensile strength in the orientation direction can reach 300-500MPa (ordinary PI film is about 150-250MPa), and the elongation at break is low (5% -10%), which can withstand long-term unidirectional tension without deformation, making it suitable as a "structural reinforcement material" (such as a reinforcement layer for composite materials and a support substrate for flexible electrons);
Excellent tear resistance: In the orientation direction, the tear resistance strength is 2-3 times higher than that of ordinary PI film, and it is not easily torn due to local forces (such as edge friction, slight impact), especially suitable for scenarios that require "maintaining integrity after edge cutting" (such as precision electronic component packaging);
Low creep resistance: When subjected to constant unidirectional stress for a long time (such as continuous stretching under high temperature conditions), the creep rate (degree of deformation) is less than 0.5%/1000h, far superior to ordinary PI films (about 1% -2%/1000h), which can maintain dimensional stability for a long time and avoid affecting equipment accuracy due to deformation (such as structural components in the aerospace field).
2、 Key advantages: high temperature resistance and environmental stability, suitable for extreme scenarios
Polyimide itself is a high-temperature resistant polymer, and unidirectional PI films inherit this characteristic. At the same time, due to the oriented arrangement of molecular chains, their environmental stability is further improved, and they can withstand extreme environments from low to high temperatures
Wide temperature range stability: The long-term use temperature range is -269 ℃ (liquid helium temperature) to 260 ℃, and it can withstand high temperatures above 400 ℃ in the short term. It can still maintain more than 80% of its directional mechanical strength at high temperatures (such as 200 ℃) without melting or softening, and is suitable for high temperature scenarios such as aerospace (engine peripheral components) and automotive electronics (engine compartment components);
Aging resistance and chemical corrosion resistance: The oriented arrangement of molecular chains reduces the permeation channels of chemical reagents, and has better resistance to organic solvents (such as alcohol, acetone) and acid-base solutions (pH 2-12) than ordinary PI films. It also has strong UV aging resistance (outdoor exposure for 5 years, mechanical performance degradation ≤ 10%), suitable for outdoor or chemical industry scenarios (such as insulation coatings for chemical equipment);
Low moisture absorption: The water absorption rate is less than 0.5% (25 ℃, relative humidity 60%), and there will be no significant expansion or performance degradation after water absorption. It can maintain stable dielectric and mechanical properties in humid environments (such as underwater detection equipment, electronic components in humid and hot areas).
3、 Practical advantages: excellent dielectric performance+lightweight, suitable for precision electronics and manufacturing
The "insulation" and "lightweight" characteristics of unidirectional PI film make it an ideal material for precision electronics and equipment fields, balancing functional requirements and weight reduction goals:
Excellent dielectric performance: The dielectric constant (at 1kHz) is about 3.0-3.5, the dielectric loss tangent value is less than 0.005, the breakdown field strength is greater than 300kV/mm, and the dielectric performance is stable in a wide temperature range (-50 ℃ to 200 ℃) and a wide frequency range (100Hz to 1GHz). It is the core insulation material of electronic components (such as flexible circuit boards, high-frequency antennas, capacitors), which can avoid signal interference or insulation failure;
Lightweight and Thinning: The density is only 1.4-1.5g/cm ³ (about 1/5 of aluminum alloy), and it can be made into ultra-thin specifications (thickness 5-25 μ m). While improving structural strength or insulation performance, it hardly increases equipment weight and is suitable for aerospace (weight reduction requirements), flexible electronics (thinning requirements) and other scenarios;
Easy to process: It can be used for subsequent processing such as cutting, hot pressing, coating (such as copper plating, aluminum plating), etc., and the directional mechanical and dielectric properties do not significantly deteriorate after processing. It can adapt to complex component forming requirements (such as bending and forming of flexible circuit boards, laminating and composite materials).
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