Micro/Mini LED production key: balance technology and cost

In recent years, micro-light-emitting diodes (Micro LEDs) have continued to grow in the footsteps of large-scale industrial and cross-industry industry chains. The sub-millimeter light-emitting diodes (Mini LEDs), which are regarded as transition technologies, have also developed rapidly over the past year. . Both have been technically challenging, but cost considerations remain a common problem.

Price should compete with OLED

"The biggest problem with Mini LEDs is not in technology but in cost." In the SID exhibition, many panel manufacturers exhibited Mini LED backlight mobile phones in this year's SID exhibition. The thickness of the module is between 1 and 2 mm. It has been very thin, and the Local Dimming Zones range from 200 to 1,000. The product completion is quite high.

♦ Jibang Consulting LED Research Center (LEDinside) Research Associate Manager Yu Chao

Although these product specifications are close to the existing high-end product grades, the number of chips used has to be more than 10,000, which means that the price of the product will be very impressive. "In such a situation, whether it can enter the market and OLED PK is the most critical issue now," said Chu Yu. In particular, mobile phones or tablet devices are light and thin, and power saving. It is still worth discussing whether Mini LEDs are suitable for such display products, and the cost issue will be a key to whether the Mini LEDs can be mass-produced in advance.

Chu Yu said that mobile phones and tablets are the most difficult applications for both Mini LEDs and Micro LEDs. After all, OLED technology in this field has matured relatively mature. Although it is only a matter of time to overcome the bottleneck of the Mini LED or Micro LED technology, reducing costs is not an easy task to overcome in the short term.

Looking at the Mini LED, it may be a great opportunity to move towards high-priced high-end TV sets. Chu Yuchao pointed out that the Mini LED backlight concept has been around for a long time, that is, direct-lit backlight. However, the size of the previous LED chip is large and the material cost is too high. Now the Mini LED concept has shrunk the LED chip size to 100 to 200μm. Or can further reduce the cost of materials, and do not need new equipment expenditure.

If the direct-lit backlight with Mini LED is used with area dimming, not only the contrast of the picture is high, but also the display effect is very good. Chu Yuchao believes that Mini LED backlight products can develop differentiated direct-lit backlight high-end models, and it is expected to compete with OLED high-end models. In the future, there will be opportunities to develop into the mainstream in the 8K high-end TV market. In addition, they are also optimistic about e-sports. The gaming monitor is expected to become one of the fastest growing areas of Mini LEDs.

Micro LED transfer and repair costs the most

Mini LED and Micro LED technology are making progress, and the advancement time may be faster than the development time of OLED in the past. Chu Yu believes that this is related to the slower technological breakthrough of OLED organic materials. Micro LED is different from OLED. It is a very mature semiconductor process. The development method is different from OLED. It needs to make breakthroughs in process, improve the yield, invest in new equipment, etc., and the speed of progress is expected to accelerate.

However, in addition to technical bottlenecks to be broken, the cost is still a major problem for Micro LED to achieve mass production at an early date. Stored in the cost structure of the current Micro LED 2K resolution, the analysis of the overall cost mostly falls on the two major projects of Mass Transfer and Repair, and the proportion is extremely extreme compared to other projects. The overall cost is about eight to ten times more than the cost of existing displays.

Many manufacturers have begun to solve problems with short-term alternatives, such as cutting and screening before transfer, reducing the cost of repair after transfer; some use monochromatic Micro LED with quantum dot (QD) color conversion material, or RGB tricolor Micro LEDs are fully colorized; others use the Redundancy mechanism to avoid the cumbersome process of repairing the planting back when the dead pixels appear, and hope to further reduce the huge transfer and repair costs.

"In the long run, whether it is a huge amount of transfer or repair costs, the most serious point is that the yield of the previous product is not mature enough." Chu Yuchao believes that how to improve the yield of all processes in the future is the key, if you can do it in the early stage of the process To perfection, in theory, the latter part can reduce the occurrence of bad points and reduce the cost of repair. Of course, the repair aspect should also find new solutions to further reduce the cost; in addition, the reduction of material usage and the improvement of material use efficiency are also The key to long-term development.

Referring to the huge amount of transfer technology, Chu Yuchao said that Taiwan’s development in this technology field is running fast. At present, there are special transfer technology patents including Yuchuang, Taiwan Institute of Technology, and Mikro Mesa Technology. In addition, Taiwan has Panels, LEDs and other industries match, and then adjust the direction of huge transfer, the development of Micro LED environment is relatively mature. Driven by major systems such as Apple, SONY, Samsung, etc., in the future, high-end TV market, AR projection solutions, etc., will have a very promising development direction, but to cut into the mainstream specifications, it depends on the ability of each factory to reduce costs. Chu Yuchao believes that it will take at least three years.

"The future of Taiwan will be the training place for Micro LED display." He is optimistic about the opportunity to develop Micro LED in Taiwan. "All technologies must have solutions, but the key lies in cost, how to balance technology and cost. , will be the key to the future," said Yu Chao.