company news about How can UV LED curing achieve non-destructive, efficient, and high-quality bonding in mobile phone screens

How can UV LED curing achieve non-destructive, efficient, and high-quality bonding in mobile phone screens

UV curing technology is a crucial step in the modern smartphone screen manufacturing process, primarily used for bonding OCA optical adhesives and LOCA water-based adhesives. By employing UV LED curing equipment, manufacturers can achieve precise light intensity control, ultra-low heat generation, and high energy efficiency, thereby ensuring perfect screen bonding and effectively preventing yellowing, bubbles, and thermal damage. It is a core technology for guaranteeing the display quality and lifespan of mobile phone screens.

In smartphone screen assembly, protective glass, touchscreen (TP), and display panel (such as OLED/LCD) need to be bonded layer by layer to ensure optical transparency and touch sensitivity.

Two main types of optical adhesives are used:

OCA (Optically Clear Adhesive): A pre-made optically clear solid double-sided adhesive that cures primarily with pressure and UV light.

LOCA (Liquid Optically Clear Adhesive): A liquid adhesive that needs to be applied first and then completely cured by UV light.

For both OCA and LOCA, UV curing is the crucial step in transforming them from a liquid (or soft solid) state into a high-strength, high-transparency elastomer.

The UV LED curing process is a precisely controlled, multi-stage industrial process designed to ensure defect-free screen bonding:

1. Pre-Curing (Positioning Curing): Before full-area curing, screen components (such as cover plates and panels) are briefly irradiated with low-energy UV light at edges or specific locations. This is typically done using UV LED point sources or tiny line sources. The light intensity and time are controlled within an extremely short range (e.g., a few seconds), just enough to allow the adhesive edges to initially solidify, precisely securing the components and preventing adhesive overflow.
2. Main Curing (Complete Curing): The entire screen area is uniformly irradiated with high-energy UV light to completely cure the optical adhesive, achieving final bond strength and optical performance. This uses UV LED line or area sources, typically integrated into the curing chamber of an automated production line. The curing equipment is set with precise irradiance dose (Joules/cm²) and peak light intensity (W/cm²). The screen passes through the curing area at a constant speed, ensuring that every area of ​​adhesive receives uniform and sufficient UV energy.
3. Post-Curing (Stress Relief): Certain specialized optical adhesives or applications with extremely high reliability requirements may require prolonged, low-intensity post-curing or low-temperature baking to further stabilize the adhesive structure, eliminate internal stress, and achieve optimal mechanical and optical properties.

Compared to traditional mercury lamps, UV LED curing systems are ideal for mobile phone screen manufacturing because they address key pain points in precision electronics manufacturing:

Heatless curing protects OLED/LCD panels, with virtually no infrared radiation, achieving cold curing. This is crucial for heat-sensitive flexible OLEDs and high-PPI (pixel density) precision panels, significantly improving yield.

Precise wavelength and efficient energy utilization. Modern optical adhesives (OCA/LOCA) are mostly designed for the UV-A band (such as 365nm, 395nm). UV LEDs emit a single, narrow-spectrum wavelength, perfectly matching the adhesive's absorption spectrum. Concentrated energy results in deeper and faster curing, ensuring thorough curing from the inside out, avoiding bubbles and delamination caused by residual liquid adhesive (commonly known as "uncured").

High stability and automated integration. LEDs can be instantly started and stopped, perfectly complementing high-precision, high-speed automated robotic arms and conveyors, enabling lean production with zero waiting time. UV LEDs exhibit minimal light intensity decay throughout their lifespan, ensuring highly consistent curing quality from the first screen to the millionth.

UV LED curing technology has become the unspoken standard defining the quality of high-end smartphone screens. Our company's UV LED curing solutions not only help manufacturers achieve lower energy consumption and maintenance costs, but also deliver unparalleled clarity and a durable, reliable screen experience to consumers through their non-destructive, efficient, and highly stable characteristics.

In the future, with the widespread adoption of flexible and foldable screens, UV LED curing, with its compact, flexible form factor and cold-curing properties, will continue to play a core role in the field of precision electronics manufacturing.