Micro LED: Are MiP and COB competing alternatives?

In recent years, Micro LED technology has been regared as the king of the future display with its excellent performance and potential low-cost advantages. However, to bring Micro LED technology from the laboratory to the market and achieve large-scale application, it faces a series of technical challenges.

Against this background, MIP packaging technology came into being and gradually became a key force in promoting the popularization of Micro LED products. Some industry insiders pointed out: “Increasing the promotion of MIP packaging is the current realistic path for the large-scale advent and popularization of Micro LED products!”

Doitvision wil guide you the practical significance, technical advantages and relationship between MiP packaging and COB packaging.

What is MiP? Why is it so critical?

MiP, the full name of which is Micro LED in Package, is a packaging method designed specifically for Micro LED. Its core idea is: first encapsulate the micro LED chip into an independent pixel unit, and then carry out subsequent integration or mounting.

The size of the Micro LED chip is very small, usually less than 50 microns, and some are even less than 10 microns. If this extremely small chip is used directly for LED display screen, it will face a series of technical problems such as difficult circuit connection, low yield, and poor maintainability.

MiP uses “pre-packaging” to turn these micron-level chips into a standard package with a stable structure and easy operation, greatly simplifying the subsequent manufacturing process.

It’s like: originally you want to lay bricks directly on the building, each brick is extremely small and difficult to operate. The MiP approach is to first combine these “small bricks” into “prefabricated panels” and then neatly splice them into a whole wall.

How does MiP technology solve the landing problem of Micro LED?

Breakthrough in the preparation of Micro LED microchips

The preparation of Micro LED microchips is the primary difficulty in realizing its application marketization. Maintaining extremely high electrical quantum effects on a smaller scale is a key technology, but in terms of the resolution granularity required in the LED display, color TV display, and automotive, the existing materials and process technologies can basically meet the needs of large-scale applications.

Take the 0202MIP chip as an example. As the latest generation of products, it has been included in the mass production schedule. By the end of 2024, more LED video screen  based on the 0202MIP chip will have been launched. This shows that in terms of microchip preparation, MIP technology is gradually promoting Micro LED towards practical application.

Integrated matching of microchip and substrate circuit Optimization

The size of Micro LED microchips is very small, while the traditional PCB board circuit has deficiencies in high-precision connection performance, making it difficult to meet the integration matching requirements of Micro LED microchips and substrate circuits.

MIP packaging processes the connection points of fan-out microchips through pre-packaging, turning micro-level (less than 50 microns) chips into Mini-level (more than 150 microns) structures, thereby greatly improving connectivity.

Even after using new glass substrate materials to solve the problem of PCB board extreme line width, the MIP fan-out connection combined with the advantage of larger size is still conducive to greatly improving the integration efficiency on glass substrates.

Significant reduction in the difficulty of mass integration

Micro LED displays face higher difficulties in mass integration. The smaller chip size and increased display PPI density increase the difficulty of mass transfer from both the quality and quantity levels. The MIP packaging process has made at least two improvements to this problem.

On the one hand, the MIP integrated with RGB packaging can be sorted and rejected for consistency. So, there is no need to worry about the waste of good pixels caused by rejection of bad pixels.

For the MIP packaging process, the required mass transfer yield is lower, and a yield of 5 9s or even 4 9s is sufficient; while direct chip CELL large-scale integration requires a yield of more than 6 9s (which can be combined with repair technology).

On the other hand, after MIP packaging, larger-sized lamp beads have more technical solutions to choose from in terminal panel integration and higher technical maturity. At the same time, due to the protection of the MIP packaging layer, the possibility of device failure is lower and the maintainability is better.

MIP and COB: From competition to “different paths to the same destination”

Limitations of early market cognition

The early market regarded MIP and COB as a competitive relationship, or even a substitute relationship, which was too one-sided. It narrowed the significance of MIP and COB and ignored the inevitable “same destination”. In fact, MIP and COB have their own unique value in the Micro LED industry chain.

Collaboration between MIP packaging,SMD and COB integration

The devices after MIP packaging can be used for “direct surface mount” technology, which can better be compatible with the largest terminal production capacity in the industry chain. It provides the possibility for the application of Micro LED in the pitch above P2.0. However, the traditional SMD technology cannot efficiently handle the large-scale integration of independent devices as small as high enough pixel density 0202.

However, MIP packaging can get the support of COB. The terminal products integrated with MIP + surface mount technology can adopt sealing and injection design to improve strength, stability and reliability.

For ultra-small MIP packaging, such as 0202 specifications, the most suitable integration process is still COB integration, that is, secondary chip-level integration of 0202MIP devices, and terminal manufacturing using mass transfer technology and COB standard process.

The intrinsic connection between MIP packaging and COB packaging

The MIP packaging itself can be regarded as the smallest COB packaging structure( a COB CELL with only one pixel and three RGB microchips). As the stability of the packaging process improves, in order to improve the downstream integration efficiency, N in one MIP packaging process can be developed on products with standardized resolution scales(small COB packaging that may contain 4 pixels or 12 pixels).

If the mass transfer process continues to mature, the scale of this packaging can be larger and directly become a Micro LED direct COB display. These developments all show that there is an inherent connection and evolution trend between MIP and COB in the packaging structure.

Mutual penetration of enterprise layout

COB packaging-level Enterprises are entering the MIP packaging market in an all-round way.  MIP packaging devices Suppliers include not only traditional packaging companies, but also COB-type LED screen terminal companies.

COB packaging and MIP packaging are highly similar in terms of process and technical difficulties, so that the progress and accumulation of the COB route in the past decade can play a good role in the MIP era. Therefore, the consistency and synergy between MIP and COB are far greater than the competitiveness.

MIP packaging technology update progress: upgrade and mass production synchronization

Combination with SMD technology and innovative solutions

MIP packaging and SMD technology are currently the most common application mode, but MIP technology is also constantly innovating. For example, the XT-CMB0202-T product of Xinying Optoelectronics can be seamlessly compatible with COB packaging technology, and the MCOB = MiP + COB solution will become an important technical path for MIP in the high-end market below P1.0 in the future.

Development of “true core” technology

MIP technology is developing “true core” technology. This technology allows MIP packaging to achieve the effect comparable to flip-chip COB packaging. It has greatly improved performance in terms of light uniformity, color mixing ability and large viewing angle accuracy. In the long run, it is more suitable for application requirements such as spacing indicators below P0.5.

Continuous breakthroughs in device and chip size

In terms of devices, 0202 is considered to be a key target product, and a single device can adapt to and meet the mainstream high-end spacing application requirements such as P0.3 to P1.2.

Further breakthroughs to 0101 can achieve more basic applications in medium-sized display products, including PC monitors above 20 inches and car screens.

On Micro LED chips, MIP is also “continuously advancing on a smaller scale.” At present, 0202 mainly corresponds to 12mil RGB chips (i.e. 2550 microns), and the package size is 250*250um. In the future, how to achieve more efficient material utilization in a smaller size is an important development direction, because the size of Micro LED particles is reduced by half, and the unit wafer can theoretically produce 4 times the pixels.

Expansion of substrate materials

In addition to MIP packaging of PCB boards, industry companies are also studying MIP packaging products based on glass substrates. Glass substrates are more friendly to mass processes and smaller-sized LED chips. They are expected to bring new opportunities for the development of Micro LED.

Future prospects of MIP technology

The continuous progress of MIP technology itself, as well as more recognition and consensus from upstream and downstream of the industry chain, deeper technical understanding and more future imagination are the prerequisites for the great development of MIP technology in 2024.

Unilumin Technology plans to expand its MIP production capacity to 6,000KK/month. Other well-known suppliers such as Doitvision are following closely. The industry predicts that from 2024 to the next few years, the demand for Micro LED screens based on MIP technology will show explosive growth.

Technological development

From the perspective of technological development, MIP packaging technology, as the upstream of COB, plays an irreplaceable role in promoting Micro LED technology from the laboratory to the market.

It not only solves the problems of Micro LED in microchip preparation, microchip and substrate circuit integration matching, and massive integration, but also achieves “different paths to the same destination” with COB packaging technology, forming a good situation of coordinated development.

With the continuous innovation and upgrading of technology, MIP packaging technology will be applied in more fields, laying a solid foundation for the large-scale popularization of Micro LED.

Market application

From the perspective of market application, the explosive growth of demand for Micro LED  will drive the development of the entire industrial chain. Upstream chip manufacturing, packaging materials and other companies will usher in new development opportunities. Midstream packaging companies and downstream terminal LED display manufacturers will also benefit from the promotion of MIP technology.

At the same time, the expansion of the application of MIP technology in emerging fields such as vehicle-mounted displays and PC monitors will further expand the market share of Micro LED.

However, we should also be aware that MIP technology still faces some challenges in its development.

For example, in terms of chip packaging and integration of smaller sizes, it is necessary to further improve the yield and reduce costs; in the application of glass substrate MIP packaging technology, some process and material issues need to be solved.

But overall, MIP packaging technology has pointed out the direction for the development of Micro LED. With the continuous advancement of technology, Micro LED is expected to occupy a dominant position in the future display field.  MIP packaging technology will also play a key role in this process.

Conclusion:

In summary, the MIP packaging technology is not only the key to solving its landing problems, but also the upstream of COB packaging technology. The two work together and develop together. Driven by both technological updates and market demand, MIP packaging technology will usher in a broader development prospect and bring new changes and opportunities.