Chemical corrosion resistance of bidirectional polyimide film and solvents it can withstand
Bidirectional polyimide film is a polymer insulation substrate, which has excellent chemical corrosion resistance, solvent resistance, and hydrolysis resistance due to its highly stable aromatic condensed ring molecular structure and high-density cross-linking system. Compared with ordinary unidirectional PI films, PET, PP, PC and other films, the biaxial stretching process makes its molecular arr
Bidirectional polyimide film is a polymer insulation substrate, which has excellent chemical corrosion resistance, solvent resistance, and hydrolysis resistance due to its highly stable aromatic condensed ring molecular structure and high-density cross-linking system. Compared with ordinary unidirectional PI films, PET, PP, PC and other films, the biaxial stretching process makes its molecular arrangement more regular and its structure denser, greatly improving its resistance to dielectric erosion. It can adapt to chemical cleaning, coating, etching process environments in multiple scenarios such as FPC flexible circuit boards, lithium battery insulation, optoelectronic displays, precision electronic coating, etc. It is one of the core substrates for electronic manufacturing.
1、 Core Performance Advantage: Chemical Corrosion Resistant Bottom Logic
Bidirectional polyimide film has strong molecular chain rigidity, high crystallinity, no hydrophilic groups, and is not easily swollen. It has extremely strong chemical inertness at room temperature. Conventional organic solutions, weak acids and bases, and industrial cleaning agents cannot destroy their molecular structure and will not cause problems such as dissolution, cracking, whitening, delamination, or dimensional deformation. After undergoing biaxial stretching and shaping, the film has uniform internal stress, which can effectively avoid stress cracking caused by solvent erosion compared to ordinary PI film, and has stronger adaptability to working conditions.
2、 Fully tolerant solvents and media at room temperature (commonly used in industry)
This type of medium can be in long-term and repeated contact, suitable for the entire process of cleaning, wiping, and pretreatment in the electronics industry, with no changes in film performance, size, or appearance:
1. Alcoholic solvents
Anhydrous ethanol, medical alcohol, isopropanol, n-butanol, etc. are the most commonly used wiping and cleaning solvents in the electronics industry. They are non corrosive and non swelling to BOPI films, and can be used with confidence for daily substrate cleaning and surface dust removal.
2. Alkanes and aromatic solvents
Toluene, xylene, white oil, petroleum ether, n-hexane, cyclohexane, etc. are widely used for ink cleaning, substrate degreasing, and auxiliary material wiping, with stable film resistance.
3. Conventional solvents for esters and ketones
Conventional industrial solvents such as ethyl acetate, butyl acetate, acetone, and butanone will not damage the film in short-term, medium, or long-term contact at room temperature, and are suitable for residual adhesive cleaning processes after coating and film application.
4. Weak acid and weak base aqueous solutions
Dilute hydrochloric acid, dilute sulfuric acid, dilute acetic acid, boric acid solutions, as well as low concentration weak alkali solutions of sodium carbonate and sodium bicarbonate, can be stably tolerated at room temperature and are suitable for conventional acid washing and weak alkali degreasing processes of circuit boards.
5. Other industrial media
Deionized water, distilled water, rust proof oil, lubricating oil, silicone oil, conventional soldering flux, rosin solution, etc., without corrosion risk, fully suitable for electronic processing and welding auxiliary working conditions.
3、 Restricted medium: There is a slight risk of high temperature/prolonged exposure
Some strong polar solvents have no effect on short-term contact at room temperature, but slight swelling and decreased mechanical properties may occur after high temperature and prolonged soaking. In the production process, it is necessary to avoid halogenated hydrocarbons such as dichloromethane, trichloromethane, tetrahydrofuran, and medium polar ether solvents. This type of medium is not suitable as a cleaning or soaking solvent for BOPI films and can only be used for instant wiping.
4、 Intolerant solvents and media (strictly prohibited from contact)
The following highly corrosive and polar media can directly damage the molecular structure of polyimide, causing film swelling, dissolution, cracking, powdering, and insulation failure. They are media that need to be strictly avoided throughout production, storage, and processing:
1. Strong polarity non proton solvent (core taboo)
NMP (N-methylpyrrolidone), DMF (dimethylformamide), DMAc (dimethylacetamide), DMSO (dimethyl sulfoxide). This type of solvent is a good solvent for PI resin, which can swell after soaking at room temperature for a long time. At high temperatures, it will directly dissolve the film and is also the core solvent for PI film production solution.
2. High concentration strong acid and strong alkali
Strong corrosive media such as concentrated nitric acid, concentrated sulfuric acid, concentrated hydrochloric acid, concentrated sodium hydroxide, and concentrated potassium hydroxide can rapidly oxidize and hydrolyze the film structure, leading to substrate damage and insulation performance failure.
3. High temperature strong oxidant
High temperature hydrogen peroxide, sodium hypochlorite solution, and potassium permanganate strong oxidation solution will gradually oxidize and degrade the surface of the film, causing the film surface to become white, brittle, and the tensile strength to decrease.
5、 Key factors affecting the chemical resistance of thin films
1. Temperature: Good corrosion resistance in low-temperature environments. The higher the temperature, the stronger the solvent molecule activity, and the film's resistance to corrosion decreases significantly;
2. Soaking duration: Instant wiping is basically risk-free, while prolonged soaking and continuous immersion can accumulate medium erosion damage;
3. Thin film process: BOPI film with sufficient biaxial stretching and no internal stress, with much better solvent resistance than ordinary cast PI film and uniaxial stretching film;
4. Surface modification: After plasma treatment and coating modification of the film, the surface structure is fine tuned, and the solvent resistance adaptability needs to be verified in advance.
6、 Industry application practical suggestions
In mass production scenarios such as FPC flexible circuit boards, lithium battery insulation packaging, high-temperature resistant tapes, and precision electronic film coatings, bidirectional polyimide films can fully adapt to conventional industrial cleaning, etching, coating, and bonding processes. It is strictly prohibited to use strong polar solvents such as NMP and DMF to clean membrane materials during production, and avoid contact with concentrated acids, bases, and strong oxidants; At the same time, the workshop warehouse needs to be stored separately, away from various taboo solvents, to avoid slow corrosion of the substrate by volatile media in the environment. For special customized working conditions, it is recommended to conduct small sample immersion tests in advance to confirm stability before mass production.
WeChat number：
Home
Product
Wechat
Telephone