LCM Backlight: The Critical Roles of Plastic Frame and Double-Sided Tape

In modern display technology, the liquid crystal screen (LCD screen) serves as a core component, and its overall performance largely depends on the integrated module behind it—the LCM (LCD Module). The LCM integrates the liquid crystal display device, driving circuitry, structural components, and the backlight into a complete module, with the luminous effect of the backlight directly determining the final visual quality of the display. Within the complex structure of the backlight, components such as the plastic frame and double-sided tape work in synergy with core parts like optical films and light sources to collectively ensure the stability and optical performance of the module.

Backlight: The Foundation of Display Visuals

The backlight (BackLight) is located behind the liquid crystal screen, and its core function is to convert point light sources into uniform and bright surface light sources. Its optical design directly affects the brightness uniformity, contrast, and color performance of the entire module, which is particularly critical for color display modules (TFT display module). A typical backlight consists of a light source, light guide plate, multiple layers of optical films, a structural plastic frame, and a driving light board, all meticulously combined. The continuous innovation in this field by many leading LCD display manufacturers in China is based on a deep understanding of the role of each component.

Plastic Frame: The Dual Guardian of Optics and Structure

The plastic frame serves as the skeleton of the backlight, providing not only essential mechanical support and protection but also undertaking important optical management functions. The choice of material is directly tailored to different product designs:

URZ2501 Material: Offers excellent reflective and light-blocking properties, commonly used in mid-to-high-end color display modules (TFT display module) to enhance contrast and color purity.

PC White Material: Often used in side-lit backlight designs, facilitating the slim profile of LCD screens.

PC White + Fiberglass Material: Enhances the structural rigidity of bottom-lit backlight products, suitable for industrial environments with stringent reliability requirements.
In projects involving customized LCD screens, the design and material selection of the plastic frame are key to achieving specific optical effects and mechanical specifications.

Double-Sided Tape: The Concealed Adhesive and Light-Blocking Specialist

Double-sided tape plays an indispensable role as an "adhesive" in LCM assembly. It is responsible for securing internal optical films such as the light guide plate, diffusion film, and brightness enhancement film, and ultimately bonding the backlight firmly to the LCD screen.

Conventional Double-Sided Tape: Available in various substrates (e.g., substrate-free, PET) and thickness options (0.03–0.30 mm). When connecting COG-structure LCD screens, selecting double-sided tape of appropriate thickness can effectively cushion pressure and prevent the occurrence of display white spots.

Black-and-White Double-Sided Tape: This is a functional material with a black side for light blocking and a white side for reflection, simultaneously performing the three tasks of adhesion, light blocking, and reflection. It is often used to define the effective display area of color display modules (TFT display module) and to secure flexible circuits (FPC), making it an important component for improving display boundary clarity and overall reliability.

Conclusion

Within the precise system of an LCM, from the light-emitting LEDs and light-guiding plates to the fixing plastic frames and double-sided tape, each component carries a unique and irreplaceable function. They work together in precise coordination, and the absence or flaw of any single link would affect the overall performance and reliability. The value of the plastic frame and double-sided tape lies precisely in their indispensable synergy with other core components such as the backlight and LCD screen, collectively forming the foundation of a stable, efficient, and high-quality display module.

About CNK

Founded in Shenzhen in 2010, CNK Electronics (CNK in brief) expanded the world leading factory in Longyan, Fujian in 2019. It is a national specialized and innovative "little giant" enterprise that specializes in the design, development, production and sales of display products. CNK provides customers with a full range of cost-effective small and medium-sized display modules, solutions, and services with excellent quality worldwide. Oriented in technology and high quality, CNK keeps sustainable development, works to offer customers  better and stable services.