Earticle

본 연구에서는 최신 디스플레이의 최신 기술인 LCD, OLED, Micro-LED, Quantum Dot(양자점)에 대한 특허 출원 동향을 분석하였다. LCD 특허 출원은 감소하는 추세를 보이며 OLED 및 차세대 디스플레이 기술로의 전환이 가속화되고 있고, 한국과 중국이 글로벌 시장을 주도하는 가운데, 미국과 일본은 응용 기술 및 재료 기술을 중심으로 특허 경쟁력을 유지하고 있는 것으로 나타났다. 특히, OLED 기술은 QD-OLED 및 플렉서블 OLED 개발 을 중심으로 특허 출원이 증가하고 있으며, Micro-LED 기술은 초고해상도 및 웨어러블 디스플레이 응용을 기반으 로 특허 경쟁이 심화되고 있는 형국이다. 또한, Quantum Dot 디스플레이 기술은 OLED 및 Micro-LED과의 융 합이 주요 연구 방향으로 자리 잡으며 관련 특허가 증가하고 있다.

This study analyzed the patent application trends of LCD, OLED, Micro-LED, and Quantum Dot display technologies. While LCD patent applications are showing a decreasing trend and the transition to OLED and next-generation display technologies is accelerating, it was found that while Korea and China are leading the global market, the United States and Japan are maintaining patent competitiveness centered on application technologies and material technologies. In particular, OLED technology is seeing an increase in patent applications centered on the development of QD-OLED and flexible OLED, and Micro-LED technology is experiencing intensifying patent competition based on ultra-high resolution and wearable display applications. In addition, Quantum Dot display technology is expanding its related patents as its fusion with OLED and Micro-LED is becoming a major research direction, and patent competition is accelerating in new application fields as well due to the development of AR/VR and next-generation display technologies.

본 논문에서는 웨어러블 디바이스용 SVGA급(800×600 pixel) Flip-chip 기반의 마이크로 LED 디스플레 이 광원 모듈 연구를 통해 마이크로LED 제작 공정을 개선하고, 시제품의 성능을 측정하여, 제품의 상용화 가능성 을 분석하였다. 먼저, 800×600 Flip-chip 기반 마이크로LED 어레이와 PM 구동 평가를 위해 32×32 어레이를 설 계 및 제작하여, 그 성능 및 제품화의 가능성을 확인하였으며, 제작 공정 기술에서 Self align 전극 형성 기술과 고집적화 어레이의 Mesa 형성을 위한 드라이 에칭 기술을 적용하여 생산성을 향상하였다. 본 연구를 기반으로 추 후 마이크로LED가 제품화시 향후 플렉서블 디스플레이 뿐만이 아닌 다양한 분야에서 적용 가능함으로 관련 산업 으로의 파급효과가 클 것으로 예상된다.

In this paper, we try to analyze the commercial potential of products by improving the micro-LED manufacturing process and measuring the performance of prototypes through research on the SVGA-class (800×600 pixel) flip-chip-based micro LED display light module for wearable devices. First, the 800×600 flip-chip based microLED array and the 32×32 array were designed and manufactured for PM driving evaluation, and their performance and potential for commercialization were confirmed. Productivity was improved by applying dry etching technology to form Mesa. Based on this study, when microLED is commercialized in the future, it is expected to have a large ripple effect on related industries as it can be applied to various fields as well as flexible displays in the future.

Micro-LEDs, which have a chip size of less than 100 × 100 ㎛², have been potential candidates for conventional LCDs and OLEDs due to their high optical power, outstanding stability, and nanosecond response time. However, Micro-LED chips are fabricated only on limited substrates due to the high-temperature metal-organic chemical vapor deposition process and lattice-mismatch issues. Therefore, the fabrication of Micro-LED displays requires complex processes such as chip fabrication, transfer, bonding, and repair. Especially, Micro-LED transfer and bonding have been critical challenges for the Micro-LED display commercialization. Here, recent advances in the transfer and bonding of Micro-LEDs are introduced, and novel Micro-LED display fabrication methods are reviewed to provide a practical outlook for both mass production and commercialization of Micro-LED displays.

A simultaneous transfer and bonding (SITRAB) process using areal laser irradiation is introduced for high-yield and cost-effective production of mini- or micro-light-emitting diode (LED) display panels. SITRAB materials are special epoxy-based solvent-free pastes. Three types of pot life are studied to obtain a convenient SITRAB process: Room temperature pot life (RPL), stage pot life (SPL), and laser pot life (LPL). In this study, the RPL was found to be 1.2 times the starting viscosity at 25℃, and the SPL was defined as the time the solder can be wetted by the SITRAB paste at given stage temperatures of 80℃, 90℃, and 100℃. The LPL, on the other hand, was referred to as the number of areal laser irradiations for the tiling process for red, green, and blue LEDs at the given stage temperatures. The process windows of SPL and LPL were identified based on their critical time and conversion requirements for good solder wetting. The measured RPL and SPL at the stage temperature of 80℃ were 6 days and 8 h, respectively, and the LPL was more than six at these stage temperatures.