Bar chart illustrating the significant reduction in chip and package size of Smartkem's MiP4 technology compared to POB and COB methods.

Smartkem unveils next-generation Mini-LED backlight technology at IDW 2025… Announces ‘MicroLED-in-Package (MiP4)’ structure featuring proprietary RDL technology

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UK-based advanced materials company Smartkem announced its next-generation Mini-LED backlight technology at International Display Workshops 2025, held at the Hiroshima International Conference Center in Japan from December 3 to 5. Co-developed with National Yang Ming Chiao Tung University (NYCU) in Taiwan and Coretronic, this technology is named ‘MiP4 (MicroLED-in-Package 4-in-series).’ It is characterized by solving the challenges of micro LED processes and maximizing price competitiveness through the convergence of advanced semiconductor and display process technologies.

While Mini-LED backlight technology currently leads the premium TV and tablet markets by providing excellent contrast ratios and color reproduction, it faces structural limitations. Mini LED chips like the existing ‘0820’ model (0.2mm x 0.5mm) cannot be miniaturized further, limiting cost reduction potential. Furthermore, while backlight driver circuits typically use 12V as the standard voltage, individual LED chips operate at around 3V, necessitating separate step-down converters. This was a major cause of power loss and complicated driver board design.

The MiP4 technology presented by the Smartchem research team at this year’s Hiroshima IDW ‘25 solved these issues with a novel approach called ‘series connection packaging’. The team placed four ultra-small micro-LED chips, each under 85µm (micrometers), onto a glass substrate and electrically connected them in series to form a single package (0.6mm x 0.6mm).

Comparison graph of Chip size (black) and Package size (blue) for POB, COB, and MiP4 technologies (Source: Smartkem)

Comparison showing significantly reduced chip and package sizes of MiP4 compared to conventional POB and COB methods (Source: Smartkem)

The most notable aspects of this research result are material efficiency and luminance performance. Smartchem announced that in testing a backlight module composed of 400 zones, MiP4 technology reduced the amount of GaN (gallium nitride) epitaxial material used by a remarkable 84% compared to the existing COB (Chip-on-Board) method. While the conventional COB method uses 73.6mm² of GaN area per backlight unit, MiP4 uses only 11.56mm², dramatically lowering material costs.

The MiP4 manufacturing process integrates advanced semiconductor and display process technologies. The research team adopted a method where the GaN LED structure grown on a sapphire substrate is separated via a ‘Chemical Lift-off’ process and then transferred onto a glass substrate. On the glass substrate, a redistribution layer (RDL) composed of a polymer insulating film and metal wiring was formed, electrically connecting four micro LEDs in series.

(a) Schematic of RDL routing for uLED series integration on glass substrate (Source: Smartkem)

(a) Schematic illustrating the RDL routing process for integrating micro-LEDs in series on a glass substrate (Source: Smartkem)

This ‘Chip-first’ and RDL-based integration process not only ensures 12V compatibility at the chip level but also provides a package form immediately applicable to SMT (Surface Mount Technology) processes, enhancing manufacturing reliability.

Material usage decreased while performance actually improved. The MiP4-based backlight module achieved a maximum luminance of 34,047 nits with an optical film applied, demonstrating significantly higher luminous efficiency compared to commercial COB products that recorded 25,619 nits.

Smartchem and the research team anticipate that once commercialized, this technology will become a powerful weapon capable of competing with OLED in the small-to-medium high-definition display market, including notebooks, tablets, and automotive displays.

Smartkem MiP4 details: (a) MiP4-based 400-zone on FR-4 PCB, (b) laminated optical film stack with 12V driving, (c) Performance comparison table between COB and MiP4 (Source: Smartkem)

(a) MiP4-based 400-zone backlight unit, (b) demonstration with laminated optical films under 12V driving, and (c) table comparing brightness and efficiency between COTS (COB) and MiP4 (Source: Smartkem)

Changho Noh,  Senior Analyst at UBI Research (chnoh@ubiresearch.com)

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