News: Markets
22 June 2021
Transition from mini-LED to micro-LED displays to be a game-changer
During 2020 and 2021 display manufacturers from Samsung to LG, from TCL to BOE, and from Konka to Hisense all launched their product lines based on mini-LEDs. Also, Apple is putting the technology into its future product lines. The take-off of backlit mini-LED displays has also paved the way for micro-LED displays, with large signage displays and TVs seeing initial adoption, notes the report ‘Micro-LED Displays 2021-2031: Technology, Commercialization, Opportunity, Market and Players’ of market research firm IDTechEx.
Mini-LEDs and micro-LEDs
Mini-LEDs are considered to be LEDs in the millimeter range, whereas micro-LEDs are in the micron range. However, in reality, the distinction is not so strict, and the definition may vary. But it is commonly accepted that micro-LEDs are under 100µm in size, and even under 50µm, while mini-LEDs are much larger.
When applied in the display industry, size is just one factor. Another feature is the LED thickness and the substrate. Mini-LEDs usually have a large thickness of over 100µm, largely due to the existence of LED substrates, whereas micro-LEDs are usually substrateless and therefore the finished LEDs are extremely thin.
A third feature distinguishing the two is the mass transfer techniques that are utilized to handle the LEDs. Mini-LEDs usually adopt conventional pick & place techniques, including surface-mounting technology. The number of LEDs that can be transferred each time is limited. For micro-LEDs, when a heterogenous target substrate is used, usually millions of LEDs need to be transferred, so the number of LEDs to be transferred at a time is significantly larger, and thus the disruptive mass transfer technique should be considered.
The differences between mini-LEDs and micro-LEDs determine their ease of realization and technology maturity, notes the report.
Two forms of mini-LED Displays
Mini-LEDs can be used as the backlight source for a conventional LCD display, or as self-emissive pixel emitters.
In terms of backlight application, mini-LEDs can improve existing LCD technology, with enhanced colors and contrast. Essentially, mini-LEDs replace the edge-type backlight’s dozens of high-luminance LEDs with tens of thousands of direct-type mini-LED units. Their level of high dynamic range (HDR) fineness sets a new record. Even though the mini-LED unit is not yet able to dim locally (pixel by pixel) like organic light-emitting diodes (OLEDs) can, at least it can meet the extreme requirements to process local dimming signals for HDR imaging. In addition, LCD panels with mini-LED backlights tend to provide better color rendering index (CRI) and can be manufactured to be as thin as an OLED panel.
In contrast to backlit mini-LED displays, which are essentially still LCDs, using mini-LEDs as the pixels creates direct emissive LED displays. This kind of display precedes micro-LED displays.
From mini-LED to micro-LED displays
Facing the difficulties in chip manufacturing and mass transfer, emissive mini-LED displays are a compromised solution regarding future micro-LEDs. From mini-LED to micro-LED displays, not only the LED size and thickness are further reduced but the manufacturing techniques involved and the supply chain will also be different. The rapid penetration of mini-LED displays, whether backlight-based or emissive, is aiding the establishment of the supply chain and assisting the accumulation of know-how and experience.
Micro-LED displays have value propositions, including wide color gamut, high luminance, low power consumption, excellent stability and long lifetime, wide viewing angle, high dynamic range, high contrast, fast refresh rate, transparency, seamless connection, and sensor integration capability. Some features are unique to micro-LEDs, so the technology is considered to be a potential game-changer in the display industry, concludes the report.
