Transfer bonding process combined in one process for the first time … We have succeeded in developing the leading innovative technology. Plant investment & process time greatly reduced to 1/10, material & repair costs to 1/100. reduced
The Korean research team has developed the world’s first next-generation display technology, which can simplify the process and significantly reduce ancillary costs. The new materials required for the new process were also developed for the first time worldwide and are intended to provide significant support to the Korean industry in further expanding its leading position in the next-generation display market.
The Electronics and Telecommunications Research Institute (ETRI) announced that the new materials suitable for the new technology have been developed to solve the challenges in the micro-LED1) Display technology.
The micro-LED display is a self-emitting display of the next generation with micro-LED2)as a pixel light source. The research team manufactured 12 micro-LEDs in 1mm2, and more vivid colors can be realized compared to the LCD3) or OLED4) Display. It also has such high luminous efficacy that it can be used in various fields such as TV and smartwatch etc.
In particular, the micro-LED display controls the RGB elements separately for precisely expressing the screen brightness and color, and inorganic semiconductors can be used for a long period of time without worrying about the burn-in phenomenon of deterioration.
In order to develop the product, micro-LEDs produced in the semiconductor process must be transferred to the display. 8K TVs need about 100 million micro LEDs, and the size is also very small, so it takes a long time to transmit and bond. The materials required to manufacture the display are also dependent on imports, so the price is very high5).
All existing procedures were based on the sequential processes: the “transfer process” and then the “bonding process”. The ETRI research team developed the new SITRAB materials6) Adhesives for use in combining the transfer and gluing processes in one process.
The research team applied a homogenized laser to the SITRAB film attached to the micro-LED for a few seconds to develop the core process of simultaneous transfer and bonding7) to meet the challenge.
The key to this developed method is to apply the homogenized laser to a large area, but only to heat the part that is to be attached to a display substrate to attach the micro-LED; this technique made it possible to avoid the inconvenience of performing the transmission and connection processes separately. The new materials suitable for the respective technology were also developed independently in order to offer the possibility of using the material not only for micro-LEDs, but also for next-generation display technologies such as mini-LEDs, etc.
By using the technology developed by ETRI, the previously high investment costs for transfer and bonding equipment can be reduced and the process simplified in order to increase manufacturability. In addition, the newly developed materials can be attached with additional micro-LEDs, even after repeated laser application, in order to make repairing the defective pixels even more convenient8th). Therefore, the limitation of the existing process of not being able to perform a repair can be resolved.
The micro-LED first presented by the research team was developed with blue color among the RGB, and the prototype with 1,225 micro-LEDs in 100mm2 was demonstrated.
In particular, the transfer and adhesive material, which is mostly imported from Japan, could be secured by the new material development without local production to open up a new market. The developed technology can also be used with domestically developed equipment in place of the expensive foreign equipment, which is favorable for commercialization.
By applying this technology developed by ETRI to the actual industrial field, the investment costs and the process time can be reduced to 1/10 compared to the existing technology, and also the material and repair costs and time can be reduced to 1/100 or less .
The research team attributed this result to efforts to develop the appropriate equipment and processes based on the know-how researched by ETRI on the differentiated new material technology over 16 years. ETRI expects the related products such as smartwatch and TV etc. to be commercialized within 2 years by transferring the technology to Korean display companies etc.
“In the R&D area, where global display companies compete, ETRI was the first institution to break the boundaries of existing displays. ETRI will continue efforts to enable Korea to become a leader in the next generation of displays and to maintain its status as a country with leading technology, “said Dr. Choi, Kwang-Seong, team leader for multifunctional materials for micro-LED in ETRI and Ministry of Science and Technology.
According to the 2020 report by market research firm Omdia, the micro-LED market is forecast to have an average annual growth rate of 65% through 2027 to reach a relevant market size of 71 billion US dollars. The supply of LED smart watch is also expected to exceed 10 million, with micro LED TVs also exceeding 3.3 million.
With this simultaneous transfer-bonding technology and process technology for applying new materials to the laser, ETRI has registered and registered 32 patents and presented 5 relevant theses.
About the Research Institute for Electronics and Telecommunications (ETRI)
ETRI is a non-profit, government-funded research institute. Since its inception in 1976, ETRI, a global ICT research institute, has made immense efforts to enable Korea to experience remarkable growth in the ICT industry. ETRI supplies Korea as one of the leading ICT nations in the world by relentlessly developing the world’s first and best technologies.
This research was carried out with the support of the Ministry of Science and ICT (MSIT) Material Innovation Leading Project, which includes the Korea Institute of Science & Technology, the Korea Institute of Ceramic Engineering & Technology and the Korea Institute of Industrial Technology as joint research institutes.
The research team announced the technology as part of the Latest News Paper * at SID Display Week 2021, the world’s largest display symposium; This allows the excellence of the technology to be recognized.
* Title of the thesis: Simultaneous Transfer and Bonding (SITRAB) Process for Mini-LED Display
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1) The display measures 1/10 of the mini LED and uses a micro LED with a measurement of around 10 ~ 100 μm
2) Light Emitting Diode (LED). Semiconductor component that emits light when a current is applied to it in the forward direction
3) Liquid crystal display. The phenomenon of light filtering when a voltage is applied in the LCD, which has both solid and liquid properties, is used.
4) Organic light emitting diode. The organic compound film which emits light by responding to voltage is used.
5) 110-inch TV that was relaunched by a Korean electronics company in March: Approximately KRW 170 million
6) SITRAB (Simultaneous Transfer and Bonding)
7) LAB (Laser-Assisted Bonding) process: Bonding process in which a homogenized laser is applied to the semiconductor chip or the housing for bonding
8) Repair or revision of the defective pixel after transfer and bonding (removing the existing LED to attach the new LED)