The development of Mini and Micro LED technologies aligns with “Haitz’s Law,” which suggests that improvements in luminous efficacy and reductions in costs drive the growth and technological progress of the LED industry. Similar to Moore’s Law in the semiconductor field, Haitz’s Law states that LED production increases twentyfold every decade while costs decrease to a tenth of their previous levels. Over the past 30 years, key trends in LED technology for display, backlighting, and lighting applications have focused on high power, miniaturization, and full color.
Mini LED and Micro LED (also known as μLED) refer to LED chips smaller than 200μm and 50μm, respectively. Like traditional LEDs, they are self-luminous and commonly used in various direct-display sizes, with each pixel illuminated by three RGB LED chips. Compared to other technologies, Mini and Micro LEDs consume only 10% of the energy of LCDs and half of OLEDs while offering 30 times the brightness of OLEDs and resolutions up to 1500PPI. They also provide high reliability, long life, fast response times, and high speed.
Over the next decade, as LED chip sizes and costs continue to decrease and production challenges are resolved, Mini and Micro LEDs are expected to revolutionize backlight and display technologies, becoming the preferred solution for commercial displays, wearables, smartphones, and computers.
The emergence of new technologies invariably spurs iterative enhancements in processing techniques. As the industry transitions from Mini to Micro LEDs, the constant miniaturization of individual LED chips has led to improvements in display quality and precision. For a product with 4K resolution, containing nearly 8.3 million display pixels or around 24 million LED chips, the production process, which includes massive chip transfers, welding, chip repairs, and drive control technologies, demands innovative solutions to its technical challenges.
Key Processes in Mini and Micro LED Production
Laser Massive Transfer
One of the first challenges in Mini and Micro LED production is the massive transfer of LED chips. Traditional mechanical transfer devices, which can move only a few dozen chips per second, are not sufficient for mass production. This has led to the development of innovative massive transfer technologies.
Several methods for large-scale chip transfer exist, including electrostatic attraction, fluidic assembly, elastomer stamp transfer, and laser massive transfer. Among these, laser massive transfer is emerging as an efficient solution due to continuous technological advancements. This method uses laser interactions with materials: when the LED substrate absorbs photons from ultraviolet (UV) light, it undergoes physical changes that cause large quantities of LED chips to detach simultaneously. Controlling laser power and energy density is essential to ensure the chips’ performance, transfer yield, and efficiency.
Juguang Technology, leveraging its expertise in photon generation and control, provides a comprehensive photonic solution for Mini and Micro LED massive transfer. Their UV-laser system is customized to balance laser power, energy uniformity, and spot size, meeting various customer requirements.
Laser Massive Welding
The second critical step in Mini and Micro LED production is large-scale welding. Traditional welding methods use reflow ovens to melt and solidify solder for connecting LED chips to electrodes, but they present challenges, including potential base distortion due to extended heating. Laser massive welding offers a more efficient alternative.
For example, a 4K Micro LED television with approximately 8.3 million pixels and 24 million RGB chips would be inefficient to weld using point-source lasers. Instead, massive welding is the ideal solution, as it can weld all LED chips within a designated area simultaneously. Juguang Technology‘s refractive optical shaping technology allows for adjustable semiconductor laser outputs, ensuring uniformity and efficiency by modifying the spot size, lines, or small spots depending on the application.
Laser Chip Repair
To enhance the yield rate of Mini and Micro LED chip transfers and welds, chip repair is a crucial step. In the massive transfer process, the precision of each chip must be controlled within ±0.5 micrometers to maintain high yield rates. Even at a yield rate of 99.999%, a 4K television would have around 260 defective points needing repair. Laser technology, known for its high precision and directionality, is ideal for this task.
Juguang Technology offers solutions for repairing Mini and Micro LED chips using its core photonics expertise. Their laser systems are tailored to accommodate different-sized LED chips, ensuring consistent repair outcomes.
Recognizing the growth potential of Mini and Micro LEDs early on, Juguang Technology began researching massive welding techniques in 2019. Over the past few years, the company has partnered with clients on laser massive transfer and chip repair projects. Their Flux H series laser systems, developed after extensive research and development, provide comprehensive photonic solutions.
Conclusion
As a globally recognized leader in high-power semiconductor lasers and applications, Juguang Technology customizes photonic solutions for Mini and Micro LED display processes. Through technological innovation, manufacturing excellence, and rapid response, the company is committed to becoming a globally trusted partner in the photonics industry.
About the Author
Wei Yi Gu is the Vice General Manager of the Pan-Semiconductor Process Division at Juguang Technology. He holds a Master’s degree in Engineering from Xi’an University of Technology. With over a decade of experience in laser applications, he specializes in high-power semiconductor laser system product development. He has led the development of Juguang Technology’s DLight H, DLight S, and Flux H series of high-power semiconductor laser systems.
About Focuslight Technology
Focuslight Technology is a national-level high-tech enterprise founded in September 2007. The company focuses on the research, production, and sales of high-power semiconductor laser components and raw materials (“Photon Generation”) and laser optical components (“Photon Control”). It is also expanding its operations in the photonics industry’s midstream, including photon application modules, assemblies, and subsystems (“Providing Photon Application Solutions”). Key areas of focus include applications in automotive, pan-semiconductor processes, and healthcare sectors.
Focuslight Technology has production bases and core technical teams in Xi’an, Dongguan, and Haining in China, and Dortmund, Germany. The company is certified by ISO 14001, ISO 45001, ISO 9001, and IATF 16949 quality management systems. In 2017, Focuslight acquired LIMO GmbH, a global leader in micro-optics technology, and completed a global brand unification in January 2022. In December 2021, Focuslight was successfully listed on the Shanghai Stock Exchange’s STAR Market (Stock Code: 688167). For more information, please visit www.focuslight.com.
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