Micro LED: The Essence of MiP Packaging as the Upstream of COB

“Strengthening the promotion of MiP packaging products is the practical path for the widespread launch and commercialization of Micro LED products!” As MiP packaging LED products are expected to surge in 2024, coupled with the enthusiasm of leading manufacturers in terms of “factory construction and capacity expansion,” industry professionals define the practical significance of MiP technology.

MiP Technology Solves the Micro LED Realization Challenges

Micro LED is hailed as the future king of displays, offering significant advantages in high performance, high reliability, and low cost. However, the commercialization of Micro LED also faces numerous technical challenges:

1. Micro LED Microchip Fabrication: Maintaining high quantum efficiency at smaller scales is the key technology challenge. For large-screen direct displays, TV displays, automotive displays, and other applications requiring high resolution, existing materials and process technologies are already meeting the needs for mass production. For example, the 0202 MiP chip, the latest generation product, is scheduled for mass production, and it is expected that by the end of 2024, more LED large-screen products based on the 0202 MiP chip will emerge.
2. Integration of Micro LED Microchips and Substrate Circuits: Micro LED chips are often smaller than 50 microns, and sometimes as small as 10 microns, which makes it difficult for traditional PCB circuits to provide the necessary connection performance. MiP packaging addresses this issue by using pre-packaging techniques to fan-out the microchip connection points, converting micro-sized chips (below 50 microns) into Mini-sized structures (above 150 microns), significantly improving connectivity.
3. The Difficulty of Large-Scale Integration: As the chip size decreases and the pixel density increases, Micro LED faces higher difficulties in mass transfer. Using MiP packaging can improve the mass transfer yield by at least twofold. The MiP packaging process allows for consistency sorting and defect elimination, eliminating the risk of wasting good pixels due to bad ones. This results in a lower yield requirement for mass transfer during the MiP process (e.g., 5-nines or even 4-nines), whereas COB integration requires 6-nines yield (with repair technology). Furthermore, larger-sized LED components, protected by the MiP packaging layer, have lower failure rates and better repairability, improving integration efficiency in terminal panels.

In conclusion, MiP technology addresses the shortcomings in mass transfer, substrates, and integration processes. From an “idealistic” perspective, it is a compromise; from a “gradual development” view, it is a realistic choice that accelerates the adoption of Micro LED using existing technologies, acting as the “balance point” for integration.

For displays with the same pitch, transitioning from Mini LED to Micro LED will result in five times or even ten times the production efficiency of microchip materials. This has significant implications for reducing costs and expanding the market for LED large-screen products.

MiP and COB Have “Converged”

In the early market, MiP and COB were seen as competitors or alternatives. This limited the significance of MiP and COB and overlooked the inherent “convergence” between the two technologies.

1. MiP packaging devices can be used for direct surface-mount processes, making them compatible with the industry’s largest terminal production capacities. This enables Micro LED applications in P2.0 pitch and above. However, is 0202 MiP packaging truly suitable for surface-mount processes? In reality, traditional surface-mount processes cannot efficiently handle such small devices with high pixel density.
2. MiP packaging can also leverage COB support. MiP + surface-mount integrated terminal products can adopt sealing and injection designs for better strength, stability, and reliability. Meanwhile, for extremely small MiP packaging devices (e.g., 0202 specifications), the best integration process is still COB, where the 0202 MiP device undergoes secondary chip-level integration using mass transfer and COB processes for terminal manufacturing.
3. MiP packaging itself can be seen as the smallest COB packaging structure, comprising a single pixel and three microchips (RGB). As the stability of this packaging technology improves, MiP packaging may develop into N-in-one solutions, incorporating multiple pixels into a small COB-like package. If mass transfer technology continues to mature, this could evolve into Micro LED COB terminal products.
4. Companies with COB packaging technology are increasingly entering the MiP packaging market, as MiP packaging suppliers include not only traditional packaging companies but also COB-type LED display terminal companies. The shared technology challenges in both processes allow the progress made in the past decade with COB to become a valuable asset in the MiP era.

It is clear that the relationship between MiP and COB is more complex than it appears. The core of this relationship is the consistency and synergy between the two technologies, which is far greater than their competition. It is foreseeable that leading COB brands will also seek a foothold in the MiP market, leveraging both technologies’ complementary and differentiating advantages for stronger market competitiveness.

MiP Packaging Technology Advancements, Upgrades, and Mass Production

MiP packaging combined with surface-mount technology is the basic application model and currently the most conventional approach. However, this does not mean that MiP cannot be innovated further. For example, the XT-CMB0202-T product from Chip Imaging Optoelectronics can seamlessly integrate COB packaging, and the MCOB = MiP + COB solution is an important technology path for MiP in the high-end market below P1.0.

Moreover, MiP technology is evolving toward the “true core” process, which applies Micro chips without substrates. This technology allows MiP packaging to achieve performance comparable to flip-chip COB in terms of light uniformity, color mixing ability, and wide viewing angle. Long-term, it is better suited for applications in markets with P0.5 pitch or below, including automotive displays.

The key progress in MiP technology is the continuous breaking of limits. The 0202 specification is seen as a critical target product, as a single device can meet the mainstream high-end pitch requirements from P0.3 to P1.2. Further breakthroughs towards 0101 specifications will enable basic applications for medium-sized displays, including PC monitors and automotive screens.

In Micro LED chips, MiP is also advancing in “smaller scales.” The 0202 product primarily corresponds to 12 mil RGB chips (2550 microns), with a packaging size of 250*250 microns. These products are just the entry-level size for Micro LED. A key development direction is achieving higher material efficiency for even smaller sizes—after all, shrinking Micro LED particle sizes by half theoretically yields four times the number of pixels from a single wafer.

In addition to PCB-based MiP packaging, industry players are also studying glass-based MiP packaging. Glass substrates are more compatible with mass transfer processes and smaller LED chip sizes.

The continuous progress of MiP technology, along with more industry-wide recognition, deeper technical understanding, and more future possibilities, lays the foundation for the large-scale development of MiP technology in 2024. Unilumin, the global leader in LED smart displays, plans to expand its MiP production capacity to 6000KK/month by the end of 2024, marking the beginning of large-scale Micro LED application capabilities. The industry expects that starting in 2024, the demand for Micro LED large screens based on MiP technology will experience explosive growth.