Technical Features and Technical Challenges of Mini LED and Micro LED

Technical Features and Technical Challenges of Mini LED and Micro LED

Emerging Display technologies such as Mini LED and Micro LED have brought a new dawn to the LED industry, which has been in the doldrums for a long time. With the technical improvement of various manufacturers, the development of upstream and downstream industry ecosystems has been actively promoted, and the technological achievements of Mini LED and Micro LED have begun to show. Now the Display products of Mini LED backlight technology can be seen in the market, and the demonstration technology of Micro LED has also continued to break through and evolve.

Apple, an iconic brand in the technology industry, has reported increasing investment in Micro LED research and development in Taiwan this year. At the same time, it has also been reported that Apple will launch iPad and MacBook products using Mini LED technology in 2020 and 2021. Therefore, people from all walks of life are optimistic that driven by major manufacturers, more brands will be attracted to introduce Mini LED display technology, driving demand to rise step by step.

With the continuous evolution of Mini LED and Micro LED display technology and the increasingly finer and finer LED chip size, LEDinside, a subsidiary of TrendForce, proposes the latest definition standards for Mini LED and Micro LED according to the current industry specifications, as well as the current two technological progress and challenges.

The origin and definition of Micro LED and Mini LED

Micro LED display technology miniaturizes the traditional LED design structure to the micron/μm level, removes the sapphire substrate, and arrays these tiny chips into display pixels that can be controlled by a single drive, achieving high brightness and low energy consumption , high-resolution and high-saturation display results.

The prototype of Micro LED technology comes from the Crystal LED Display released by Sony in 2012. The 55-inch display uses 6.22 million Micro LEDs to create high-resolution display pixels. However, the manufacturing method at that time was to embed a single LED, which was time-consuming and labor-intensive, and also highlighted the key manufacturing challenges of Micro LED.

Therefore, Taiwanese LED manufacturer Epistar proposed the concept of Mini LED, which also reduces the size, but retains the sapphire substrate, so it can still be produced with existing equipment. The production difficulty and cost are lower than Micro LED, and it can enter the commercial market as soon as possible.

In the past, LEDinside used 100 microns (micron / μm) as the size boundary between Micro LEDs and Mini LEDs, and defined the grain size above 100 microns as Mini LEDs and smaller than 100 microns as Micro LEDs. However, due to recent advances in related technologies, manufacturers have been able to manufacture Mini LED products with dimensions smaller than 100 microns but still with sapphire substrates. Therefore, LEDinside redefines the Micro LED size below 75 microns without a sapphire substrate.

Micro LED and Mini LED technical features and current technical challenges

Although some people thought that Mini LED was a transitional stage in the evolution of display technology towards Micro LED, as Mini LED gradually matured, it began to step out of its own market positioning. Currently, it is mainly used in multi-zone backlight displays and large-scale RGB small-pitch displays.

In terms of backlight applications, the Mini LED backlight display can be dimmed in a full-matrix manner, such as low-resolution black and white images, enhancing the high contrast and high resolution of the display image to achieve HDR effects. At the same time, the size of the Mini LED chip has been continuously reduced, which can increase the light control area and make the picture more detailed.

Another major application of Mini LED is RGB small-pitch displays. Mini LEDs are packaged in a small size to create a large-size display screen with a pixel pitch lower than P1.0mm, which has the opportunity to create new mainstream display screen specifications.

Regardless of whether it is a partitioned backlight display technology or an RGB small-pitch display, the number of Mini LED chips used is increased by tens of thousands of times compared with traditional applications, and the requirements for chip detection and sorting and subsequent transfer of parts are greatly improved. Although Place can be used, the yield and speed are not as good as new equipment. Epistar, which has greatly expanded its factory this year, is focusing on the back-end process, purchasing a large number of transfer and punching equipment, as well as sorting and testing machines, aiming to accelerate the volume of Mini LEDs.

The continuous research and development of Micro LED display technology may open up new application fields. Micro LEDs that remove the sapphire substrate and are more miniaturized are not only thinner and lighter, but also have the opportunity to integrate into different materials. Current high-profile display applications include AR/VR devices, automotive screens, and high-resolution wearable products.

In order to further realize the dream Micro LED display products, the goal of manufacturers at this stage is to continuously optimize the technology and reduce production costs. Due to the smaller size of Micro LED die, the luminous efficiency needs to be further enhanced, and the ultra-small size can be easily handled by existing equipment. Therefore, whether it is LED manufacturing, transfer, testing, etc., it depends on the cooperation of upstream and downstream manufacturers. If it can expand with semiconductor material and equipment manufacturers, it will have the opportunity to do more with less.

Apple’s active development of new display technologies is also seen as the key to the merger of Epistar and Lextar, two major LED chip manufacturers in Taiwan. In mainland China, Sanan Optoelectronics, the largest LED chip manufacturer, has officially established a joint laboratory with panel manufacturer Huaxing Group TCL to develop Micro LED display technology and related materials and equipment.

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