What are the advantages of using polyimide as a base film material?

Polyimide is an aromatic heterocyclic polymer compound containing imide chain segments in its molecular structure. It is a very high-quality base membrane material in the membrane manufacturing industry. The unique properties and temperature stability, chemical resistance, high mechanical strength, etc. given by the molecular structure have made it one of the first choices for membrane manufacturing materials:

1. First of all, polyimide has excellent thermal stability and can withstand high and low temperatures. The temperature range depends on the type of polyimide and its formulation. Under high temperature conditions, it can usually withstand continuous operating temperatures of about 200°C to 300°C. Special polyimide formulations, such as those based on polyetherimide (PEI), can even withstand temperatures as high as 350°C or higher. They are widely used in aerospace, automotive, electronics and other industries involving high temperature exposure; under low temperature conditions, it can withstand sub-zero temperatures without significantly reducing or losing mechanical properties. Also due to different formulations, most polyimides can still maintain their functions and characteristics at temperatures as low as -100°C or lower.

2. Let's talk about its chemical resistance. It has excellent resistance to a variety of chemicals, including solvents, acids, alkalis and oils, such as hydrochloric acid (HCl), sulfuric acid (H2SO4) and nitric acid (HNO3), as well as alkalis such as sodium hydroxide (NaOH) and potassium hydroxide (KOH). Generally speaking, it remains stable in the pH range from highly acidic (pH 1-2) to highly alkaline (pH 13-14), and the performance degradation and loss are relatively small. Even so, it is still necessary to pay attention to it in use. If it is exposed to extreme pH conditions for a long time, or exposed to high concentrations of acid or alkali, it may cause a certain degree of degradation or chemical corrosion of polyimide, including in some specific cases, such as polyimide formulas or additives used may have different pH tolerance limits, etc. It is recommended to check the manufacturer's specifications and conditions for the specific polyimide material used before selection and application to ensure that it is within the normal pH tolerance range.

3. Polyimide has a relatively low coefficient of thermal expansion (CTE). It expands and contracts very little with temperature changes. The formula and processing conditions are different, but it is usually in the range of 30-50 ppm/℃ or 30-50 µm/m℃. This advantage makes it more widely used in applications with high requirements for dimensional stability, because when affected by temperature changes, the size of polyimide film changes very little, which helps to maintain the integrity and shape of the material within a wide temperature range. In industries such as microelectronics, semiconductor manufacturing and optical equipment, it can maximize the precise tolerance and dimensional accuracy, and reduce the risk of failure caused by warping, delamination or stress.

4. Polyimide film has excellent electrical insulation properties due to its high dielectric strength and low dielectric constant. The maximum electric field strength that the material can withstand without electrical breakdown, its dielectric strength ranges from about 5.9 to 11.8 kilovolts per millimeter (kV/mm). This high dielectric strength enables polyimide to effectively insulate electrical components and prevent current flow; the low dielectric constant is between 3 and 4, which can ensure signal integrity and the use of minimum capacitance in high-frequency circuits or communication systems; other electrical insulation properties such as low dielectric loss tangent (0.001 to 0.01), volume resistivity (10^13 to 10^16 ohm-cm), etc. make polyimide film suitable for a variety of applications, including electrical insulation tapes, flexible printed circuit boards (PCBs), wire coatings, and other electronic components that require effective electrical insulation.

5. Some types of polyimide films show good optical transparency in the visible and near-infrared spectra, allowing light to pass through with minimal absorption or scattering, and the transmittance in the visible spectrum (400-700 nanometers) can reach 80% or more, which means that at least 80% of the incident light in the visible range can pass through the film without significant absorption or deformation. It is widely used in some industries that require display technology, optical filters, and flexible electronic devices.

6. The last thing to talk about is the mechanical strength, flexibility and compliance of the polyimide film. Its long-chain polymer structure is composed of strong covalent bonds, which makes it strong and resistant to deformation under mechanical stress, and has high tensile strength, tear resistance and dimensional stability; at the same time, its molecular structure also provides flexibility and elasticity, allowing the film to withstand bending, folding and stretching without causing significant damage or loss of performance. It is also widely used in industries such as flexible electronics, flexible displays and medical equipment.

From the above analysis, it can be seen that the molecular structure of polyimide gives it a series of favorable properties. In the related industries of base film application, its characteristics include high temperature stability, chemical resistance, mechanical strength, low thermal expansion, excellent electrical insulation, optical transparency and flexibility, etc. It has become the most widely used and ideal base film material in the electronics, aerospace, automotive and medical industries. This should also be a fact that is obvious to all in the application of modern polymer materials. It has become the most widely used and ideal base film material in the electronics, aerospace, automotive and medical industries. This should also be a fact that is obvious to all in the application of modern polymer materials.