Halogen-free black cover film is a black insulating protective film made from a halogen-free (e.g., chlorine, bromine, etc.) flame-retardant material system, typically consisting of a polyimide (PI) film or polyester (PET) film coated with a special halogen-free adhesive. It not only boasts excellent electrical insulation, heat resistance, and dimensional stability but also plays an indispensable role in various high-end manufacturing fields due to its light-blocking and heat-absorbing properties of black color, as well as its compliance advantages of being halogen-free and environmentally friendly. Its primary application scenarios can be summarized as follows:
1、 Internal components of consumer electronics and mobile terminals
In devices such as smartphones, tablets, laptops, and smartwatches, the internal space is extremely compact and the electromagnetic environment is complex. The halogen-free black coating plays multiple roles:
Flexible Circuit Board (FPC) Coverage Protection: This is its most essential application. The black cover film is adhered to the surface of the FPC, providing insulation, anti short circuit, scratch and moisture protection. Meanwhile, the black appearance can effectively absorb internal stray light, eliminate reflection interference, and help improve the detection accuracy of optical sensors such as ambient light sensors and distance sensors.
Battery module insulation and heat dissipation assistance: At the junction of the lithium battery cell ear or the position of the protective plate, a black covering film provides reliable insulation barrier. Its black surface has a high thermal radiation coefficient, which helps to quickly radiate local heat and assist in heat dissipation management.
Antenna and wireless charging module shielding layer: On the back of the 5G antenna soft board or wireless charging coil, a black covering film can be used as the base material for the shielding layer. While providing insulation, the black characteristic can reduce the false triggering of photosensitive components by light.
2、 Automotive electronics and components for new energy vehicles
With the evolution of automobiles towards electrification and intelligence, the number of electronic components inside the car has surged, requiring extremely high requirements for material temperature resistance, flame retardancy, and environmental protection:
Automotive sensors and camera modules: The millimeter wave radar, laser radar, and onboard camera modules required for autonomous driving heavily utilize flexible circuit boards. The halogen-free black cover film is used to wrap these precision circuits, and its black inner wall can effectively suppress the interference of optical stray light on CMOS sensors, ensuring imaging quality; Simultaneously meet the high-temperature working environment requirements of automotive standards (usually requiring tolerance to 105 ℃~150 ℃) and halogen-free flame retardant standards.
Power Battery Management System (BMS) collection harness: A flexible flat cable (FFC) or FPC used for voltage and temperature sampling inside a new energy vehicle battery pack, covered with a halogen-free black coating on the surface. It can resist slight corrosion from electrolytes and coolants, and due to its black characteristics, it plays a role in light and heat absorption and temperature equalization inside the battery pack, while meeting UL94 V-0 flame retardant safety requirements.
Central control instrument panel backlight module: Inside the car display screen backlight module, a black cover film is used to block light and fix the optical film, preventing uneven screen brightness caused by light source crosstalk and ensuring clear and readable driving information.
3、 Display panel and backlight module optical system
In liquid crystal display (LCD) and organic light-emitting diode (OLED) modules, optical purity is crucial:
Light blocking and reflection elimination: Black covering film is commonly used for the light blocking tape on the side of backlight modules, as well as the covering layer of LED light strip flexible boards. It can completely block the lateral leakage of backlight and absorb the stray light generated by internal mirror reflection, improving the contrast and color saturation of the display screen.
COF (COF) packaging protection: In narrow bezel OLED screens, the driver IC is directly bound to the flexible film, and this area is covered and protected with a high-precision halogen-free black cover film. It can not only insulate and prevent moisture, but also use the black light absorption characteristics to avoid reflection in the driver area that affects the display quality.
4、 Industrial and Professional Electronic Equipment
In the fields of industrial control, medical electronics, and aerospace with strict stability requirements, halogen-free black coating films are also widely used:
Industrial control boards and modules: used for internal connection cables of PLC control modules, servo drives, or insulation sheaths of micro FPCs, providing reliable protection against oil stains, chemical corrosion, and a wide temperature range (-40 ℃~130 ℃).
Medical electronic sensors: On the FPC of miniature sensors such as portable monitors and endoscope probes, the black covering film ensures biocompatibility (meeting halogen-free and non-toxic requirements) and provides excellent anti bending performance, meeting the dynamic bending requirements of flexible circuits.
Military and aerospace wiring harness: In situations where weight and radiation resistance are strict requirements, halogen-free PI based black covering film is used as a wrapping protective layer for lightweight wiring harnesses. Its black characteristics help with passive thermal control (heat absorption and radiation balance) of spacecraft under extreme temperature differences.
5、 Alternative upgrade scenarios driven by environmental compliance
In addition to the functional scenarios mentioned above, halogen-free properties themselves are becoming mandatory choices:
International brand supply chain access: Leading companies such as Apple, Samsung, Huawei, Tesla, etc. have explicitly required that their electronic component materials must meet the IEC 61249-2-21 or JPCA-ES-01 halogen-free standards. Therefore, in all the above application scenarios, traditional halogen containing cover films are being rapidly replaced by halogen-free black cover films to meet environmental regulations (such as RoHS, REACH) requirements for export to markets such as the European Union and North America.
Summary
The application scenarios of halogen-free black coating are highly concentrated in four major fields: consumer electronics, automotive electronics, display optics, and high-end industry. Its value lies not only in the green and environmentally friendly attributes brought by "halogen-free", but also in the composite advantages of light shielding, heat absorption, anti reflection properties endowed by "black", as well as excellent insulation and heat resistance performance. With the increasing lightweight and miniaturization of electronic devices and the continuous increase in the penetration rate of new energy vehicles, the application boundaries of halogen-free black coating film are still expanding, becoming a key functional and compliant basic material in modern precision electronic manufacturing.
