Polyimide Film: Key Applications & Manufacturing Processes
What Is Polyimide Film
Polyimide (PI) film is a high-performance polymer film with outstanding thermal stability, excellent electrical insulation, strong mechanical properties, and chemical resistance. Typically amber in color, it is widely used in electronics, electrical engineering, aerospace, automotive, and new energy industries.
Key Properties of Standard Polyimide Film
Material: Polyimide film
Thickness: 60±5 μm
Backing thickness: 25±2 μm
Adhesive: Silicone
Peeling strength: ≥200 N/m
Elongation: ≥40%
Dielectric breakdown: ≥4.5 kV
Heat resistance: Continuous use at 180°C
Color: Amber
Width: Customizable
Roll core: 76 mm plastic core
Storage: 23°C, 65%RH; valid for 6 months
Main Applications of Polyimide Film
1. Electronics & Microelectronics
Flexible printed circuits (FPC) substrate and coverlay
Chip packaging stress buffer layers and passivation coatings
High-temperature insulating spacers for lithium batteries
Insulation for motors, coils, and transformers
Dielectric layers in capacitors and microwave components
2. Automotive & EV
Slot insulation and phase insulation for drive motors
Wrapping for high-voltage cables and busbars
Thermal and electrical barriers in battery packs
Insulation for sensors and control units
3. Aerospace & Aviation
Thermal control films for satellites and spacecraft
High-temperature insulation for engines and wiring
Lightweight structural composite components
Radiation-resistant insulating materials
4. Electrical Engineering & Industrial
Magnet wire and enameled wire topcoat insulation
High-temperature labels and barcodes
Mold release and high-temperature masking
Welding and powder coating protection
5. Flexible Displays & Photonics
Base and cover films for foldable OLED screens
Transparent flexible substrates for solar cells
Optical waveguides and photoelectric devices
Manufacturing & Processing Methods
1. Core Production: Two-Step Process
Poly(amic acid) (PAA) SynthesisDianhydride and diamine monomers react in a polar solvent to form a high-viscosity PAA precursor solution.
Imidization
Thermal imidization: High-temperature heating removes solvent and triggers cyclodehydration to form PI film; simple and widely used in China.
Chemical imidization: Uses dehydrating agents and catalysts at low temperature; higher performance, widely adopted internationally.
2. Film Forming Technologies
CastingPAA solution is extruded through a die onto a moving steel belt, dried, and imidized. Suitable for large-width, high-thickness uniformity films.
Biaxial StretchingImproves strength, dimensional stability, and heat resistance; used for high-end electronic-grade PI film.
Dip CoatingSimple equipment; used for coating on metal foils or wires; may introduce trace metal particles.
3. Secondary Processing
Die Cutting: Precision shaping into tapes, gaskets, and custom parts.
Lamination: Bonded with adhesives or thermally to metal foils, adhesives, or other films.
Surface Treatment: Plasma or corona treatment improves adhesion and printability.
Coating: Coated with silicone, acrylic, or thermosetting adhesives to make PI tapes.
Why Choose Polyimide Film
Extreme temperature resistance: Stable from cryogenic to 180°C continuously.
Excellent electrical insulation: High dielectric strength and low dielectric loss.
Good mechanical performance: High tensile strength and tear resistance even when thin.
Chemical stability: Resistant to oils, solvents, fuels, and radiation.
Dimensional stability: Low thermal expansion, ideal for precision devices.
Polyimide Film Applications & Use Cases
Electronics & Circuit Protection
High-temperature masking for PCB soldering and wave soldering
Insulation protection for FPC flexible circuits
Solder masking for gold fingers and circuit boards
Battery & New Energy
Insulation isolation for lithium-ion battery cells and modules
Cathode/anode insulation wrapping for power batteries
High-temperature insulation for battery PACK assembly
Electrical & Motor
Slot insulation and phase insulation for small motors
Coil wrapping for transformers and inductors
High-voltage cable insulation reinforcement
Automotive & EV
Insulation for EV motor windings and busbars
High-temperature protection for automotive sensors
Battery thermal management insulation layers
Industrial & Surface Protection
High-temperature masking for powder coating and painting
Mold release film for composite materials
High-temperature labels and barcode carriers
Aerospace & Aviation
Thermal control film for satellite and spacecraft components
High-temperature insulation for aviation wiring systems
Lightweight insulation for engine peripherals
Flexible Display & Photonics
Base film and cover layer for foldable OLED screens
Flexible substrate for thin-film solar cells
Optical waveguide insulation for photoelectric devices