Micro-LED Production

Tianma Microelectronics announced that it has developed a new side wiring technology that enables completely seamless tiled microLED displays. The new technology is based on a new process that is much more cost effective compared to other processes, in fact Tianma says it can reduce the cost of side wiring deposition by up to three times.

Tianma shared some details about its first tiled microLED displays. These offer a very small pixel pitch of 0.4 mm, and are based on an LTPS backplane. Tianma also revealed that it is using a laser-bsaed transfer process. The company is now running trial production, and it hopes to improve the yields and production efficiency in 2025, and then move to small batch mass production.

Aixtron announced its financial results for Q3 2024, with solid orders and revenue, despite a slight miss on guidance due to a project delay. This project was a large order for a microLED customer, with tools shipments pushed to December instead of October.

Aixtron says that "despite the news from Apple and ams OSRAM" the microLED industry is continuing to work on the technology, and the company received orders from several customers building R&D and pilot production lines. Aixtron expects its microLED revenues in FY2024 to be at high double-digit million euros.

During the company's recent conference call, AUO said that the company is "making significant progress" in MicroLED technology, transitioning to a 4.5-Gen line. AUO's current microLED production line is referred to as a 1-Gen line, used to produce commercial wearable displays (although we understand yields are very low and production costs are still extremely high). The company hopes its new larger line will improve production efficiency and cost structure.

AUO said that the new production line will enable it to start producing automotive displays, which are expected to launch by 2026 or 2027.

In August 2023, China-based BOE HC Semitek started building its $700 million microLED epiwafer production line in Jinwan District, Zhuhai, China.

The company now held a ceremony marking the beginning of sample wafer production at the new line. This is the first phase of this project, and total investment to date is $275 million. It is likely that ramping up will take some time and full scale production of the first phase will take place later in 2025. When the fab is complete, with all three phases, it will have a yearly capacity of 58,000 6-inch microLED wafers. 

Researchers from Korea's Kookmin University in Seoul, led by Prof. Young Rag Do, have developed a novel top-down process to fabricate and isolate sub-micron GaN microLEDs. The process combines electrochemical etching and sonochemical separation of the etched porous layer to isolate the microLEDs.

The researchers have used the process to produce Au-coated GaN blue LEDs that offer an EQE of 6.21% (at 4.0 V) and a luminous efficacy of 1,070 cd/m2 (at 10.0 V). The LEDs themselves had a diameter of 750 nm, these are true sub-micon LEDs.

Pyramidical GaN microLED develop Polar Light Technologies announce a partnership with die bonding solution developer Finetech, to co-develop microLED technologies. The two companies already started developing microLED microdisplay applications. 

Polar Light Technologies and Finetech developed a modified flip-chip cold bonding technique that ensures accurate alignment between the microLEDs and the electronics. The two companies say that in early trials, this method showed an impressive 85% success rate, proving its potential for large-scale manufacturing.

In 2021, Visionox's Vistar announced that its full-process pilot microLED production line is now capable of producing displays, from driver backplane, through transfer process to full module production. The LED chips themselves are produced by a third party.

Today we understand that Vistar's Chenxian Optoelectronics (its JV that is in charge of the microLED line) has held a ceremony as it has moved in equipment to its mass production line. It is reported that the company will install more than 200 pieces of equipment in the next 2 weeks. It could be that Vistar is scaling up its line, or maybe it is also adding capabilities.

The microLED display technology is highly promising, as these displays offer increased brightness, efficiency and lifetime over the current LCD and OLED displays. However adoption of microLED displays in the major display markets is still years away. One display segment that could see adoption of microLED display sooner, is the transparent display sector.

Transparent displays are very interesting and have been researched for many years - and we have seen commercial adoption of transparent LCD, LED and OLED displays. These never achieved meaningful market success, but microLED developers hope that once microLED transparent displays are available this could change, thanks to the higher transparency and brightness offered by microLEDs compared to OLEDs and LCDs.

In recent years, we have seen many companies demonstrating transparent microLED prototypes, and even deploying some solution commercially. We will detail some of these recent advances below.

During the company's recent conference call, AUO said that the company is undergoing a strategic transformation, focusing on mobility solutions, vertical solutions, and the display segment. The company gave several interesting statements regarding its microLED project and investments.

First of all, the company says that microLED is a priority for the company, and it plans to allocate more resources into its microLED projects. AUO says that its microLED technology is 'gaining traction', and that it is producing microLED displays commercially, but it did not detail more. The company believes it is the leader in microLED development.

In June 2022, Tianma Microelectronics announced plans to establish a 1.1 billion Yuan ($164 million USD) full-process microLED pilot line, in Xiamen. A few days ago, Tianma announced that its production line has commenced trial production. The new production line is co-located with a 8.6-Gen LCD fan at the Tongxiang High-Tech New Town in Xiamen.

Tianma also detailed the first microLED display is produced at the new plant, a 7.5" module aimed towards tiled displays, that offers a brightness of 600 nits and a low 5% reflectance. This is the first time we hear of a tiled microLED display from Tianma, and hopefully Tianma will soon show a large-area TV based on these modules.