WHAT IS MIP?
MIP (Micro LED in Package) in the LED display industry is a chip-level packaging technology. Its process is as follows: Micro LED chips are transferred to the carrier board through mass transfer technology, packaged, cut into small packages, and then split and mix BIN , and taping.
The LED display factory then uses MIP packaging, carries out the traditional SMT process, makes a display module, and completes the production of the final display. The completed module can also support the surface coating of the screen (such as GOB).
Unlike technologies such as COB and IMD, which package multiple chips, the basic structure of MIP includes only one complete pixel.
WHAT IS COB?
COB, chip-on-board is a new type of lamp packaging method for LED display production, which is different from traditional packaging technology. Specifically, the bare chip adheres to the PCB with conductive or non-conductive glue, then electrically connected, encapsulates the chip and leads with adhesive.
In this way, from the packaging of the diode chip to the LED display module is completed by the packaging factory, there is no need for SMT of the module, which simplifies the production process of the LED display, makes the production process more simplified, and the pixel
pitch of the screen can be much smaller, The reliability is doubled, and the cost can be very low in the future.
COB is a disruptive innovation with many advantages
Low power consumption and long life span
The COB packaged LED display has the characteristics of strong heat dissipation, low power consumption, and long life because the heat is quickly dissipated directly through the PCB board, the thermal resistance is small, and the operating temperature of the COB display is low.
Integrated module, eliminating the traditional module SMT process
Due to the integrated module design, the LED display screen in the COB package saves multiple processes and components required by traditional SMD-packaged LED screens, hence reducing installation space and weight, simplifying installation steps and methods, and making the display screen more efficient. Simple, more convenient maintenance, and so on.
Finer pitch, larger angle, deeper contrast, more delicate color
Because by using COB packaging, there is no physical barrier between the light-emitting chips and more pixels in the LED display unit, it can achieve a smaller pitch below P1.0.
It is a surface light source that has a bigger luminous angle.
It gets a clearer image, deeper contrast, and more abundant color.
WHY MIP COMES OUT?
From the perspective of large-size LED direct-view display products, the packaging structure of LED chips mainly includes three technologies: SMD, IMD, and COB.
The LED direct-view display products below the P1.0 pitch mainly adopt IMD and COB technologies. Both can almost meet the P0.4-P0.9mm that has been launched so far.
Why is there the development of MIP packaging technology?
Limitations of SMD
As the most mature technology, SMD can cover the application market above P1.0mm, but in the application, the LED diode is easy to be knocked off or dead, and the reliability is relatively poor.
Moreover, it is difficult for SMD-independent devices to achieve P1.0 or less.
Limitations of IMD
IMD combines the characteristics of SMD and COB. It can cover P0.4~P0.9mm, and its anti-collision ability is stronger than SMD, and its reliability is also relatively strong.
However, the IMD all-in-one packaging structure determines the pitch. One IMD can only be used for one pitch. For example, the 4-in-1 IMD for P0.9mm cannot be used for other pitches.
And in this way, if the pitch is smaller, such as P0.4, is it necessary to use a 12-in-1 IMD? If more LED chips are packaged in a single structure, IMD becomes a small COB!
COB Current Challenges
By 2023, COB packaging is also facing some challenges
Difficult to repair a single lamp
For the maintenance of COB lamps, the difficulty of single-lamp maintenance is relatively high. One of the biggest problems in single lamp maintenance is that when repairing a lamp, the surrounding circle will be smoked by the welding torch, and a circle will appear around the lamp.
Not perfect color consistency
LED display with COB is prone to modular chromatic aberration.
When the scale of COB production is not large enough, the cost of chip light and color separation is high, and the finished display screen needs to be calibrated to improve the consistency of the display.
High manufacturing cost
The first pass rate of the packaging process is a challenge.
Due to its characteristics, the COB packaging works on a large board. This board has a maximum of 1024 lights. Compared with SMD, if one single light is broken during SMD packing, it only needs to replace one light.
However, after the packaging of 1024 lamps in the COB package is completed, a test must be carried out, and the glue can only be sealed after all the lamps are confirmed to have no problems. How to ensure that the 1024 lights on the whole board are completely intact, the one-time pass rate is a very big challenge.
Finished product pass rate is a challenge
For the COB module production, after the chips are sealed, the IC drive device must undergo a reflow soldering process. How to ensure that the lamp surface will not be damaged by the high temperature of 240 degrees in the furnace during the reflow soldering process. This is another big challenge!
Single-pixel package COB
MIP is like a COB package in the form of an independent pixel: it has the reliability of COB chip-level integration and the flexibility of an independent chip, and the reliability requirements for mass transfer in the micro era are 1-2 orders of magnitude lower than COB.
The most notable difference between the two is that COB is an integrated package, and MIP is a discrete device package. As a discrete device, the performance advantages of MIP technology are prominent.
High compatibility, the production process is the same as traditional SMD, IMD
MIP is a typical independent chip bead package and is compatible with downstream SMT processes.
In terms of the manufacturing process, MIP technology can match the traditional process of LED display, which means that MIP has higher compatibility in many aspects. For example, LED display manufacturers can use current SMT equipment with a small investment.
One package fits multiple small pitches
The MIP package is also versatile, that is, a MIP that can be used to produce LED screens with multiple pixel pitches. For example, a 0.4 MIP lamp can manufacture P0.5 to P1.2mm LED displays. In this regard, it is completely opposite, both COB and IMD are “package structure determines the final pixel pitch”
MIP is almost the “optimal solution” for mini/micro larger pitch LED direct display screens, suitable for P0.7~P1.8mm Display
MIP devices can realize good separation and mixing of wavelength and brightness of chip, which can make perfect color consistency and achieve better visual effects.
MIP adopts flip-chip common cathode structure, which has higher reliability and more energy saving. Because of these a little larger pitches, the application of COB technology on these pitches displays at present is not so cost-effective.
Facilitate testing and post-maintenance
MIP packaging is also easier to test and repair later.
Discrete devices offer significant advantages in testing, debugging, conformance selection, and repair.
Lower manufacturing cost than COB
At present, the cost of P1.2mm by MIP technology is equivalent to that of P1.2mm displays produced by COB and SMD, but when the pixel pitch is smaller than P1.2, the comprehensive manufacturing cost of MIP technology is lower than that of COB technology and SMD technology.
Higher yield rate
The essence of MIP (Micro LED in Package) is the combination of Micro LED and discrete devices, that is, the original large-area entire COB display module is divided into smaller separate packages. It is easier to control the yield rate in a smaller area. At the same time, the test process is moved from the chip end to the packaging phase, which will effectively reduce the cost.
MIP does not require as high a mass-transfer success rate as COB
The difficulty of mass transfer yield is not the “mass volume”, but the “yield rate”. The industry once believed that the yield rate of mass transfer needs to reach 99.9999% before it can be applied, that is, in a 4K screen, only about 8 bad transfers can be accepted.
Because MIP has to do “discrete device” cutting, final packaging, and testing after the mass transfer of chips, it is not so sensitive to the yield of mass transfer.
Bigger chance in potential cost reduction
At present, the most important cost of Micro LED is chip and transfer repair. Among them, the chip cost accounts for nearly 30%. The cost reduction in the future of Micro LED naturally requires smaller-sized chips. From this perspective, MIP is undoubtedly more in line with the future price reduction trend of Micro LED.
MIB has the advantages of both SMD and COB
MIP packaging technology is essentially a combination of COB technology and SMD technology. It has the characteristics of good color consistency and easy maintenance of SMD, and also has the advantages of high reliability of COB.
MIP VS COB VS IMD VS SMD
■ In terms of electrical connection, MiP and COB are the best, followed by IMD and SMD;
■ In terms of contrast, MiP performed best, followed by IMD and COB, and finally SMD;
■ MiP and COB perform best in terms of thermal cycle thermal shock;
■ In the manufacturing process, SMD and IMD adopt SMT process, COB adopts Pick&Place process, and MiP is compatible with both SMT process and Pick&Place process;
■ In terms of repairability, MiP is better than SMD and IMD;
■ For LED chip size requirements, SMD can only package chips larger than 145um, IMD and COB can package chips larger than 125um, and MiP can package the smallest LED chip size, which can be below 60um;
■ In terms of lamp package size, the mainstream SMD size is mostly above 1010 (>=P1.2), while MiP can be below 0404;
■ In terms of consistency, SMD, IMD and MiP are convenient for mixing wavelength and brightness, and effectively eliminate the Mura effect
■ In terms of flatness, MiP and COB have the highest flatness, followed by IMD, and finally SMD.
■At the display level, MIP and COB can achieve the smallest pixel pitch, followed by IMD, and SMD is more limited in pixel pitch.
FUTURE OF IMD, COB, AND MIP
Will IMD vanish?
Regarding the competition between MIP and COB, the industry now has a lot of consensus: for example, the flexibility of MIP will bring rapid scale growth; under the joint competition of MIP and COB, the “compromise” technical solution IMD may be the first to be marginalized or withdraw from history stage……
COB technology is gradually maturing
The current disadvantages of COB technology lie in the difficulty of color consistency, the difficulty of detection and repair, the higher reliability requirements of the packaging process, and the inability to perform single-pixel spectroscopic screening.
However, with the development of COB technology over the years, a more mature and reliable supply system has been increasingly established, and the market size is still expanding. The “technical problems” mentioned above have been initially resolved, and are moving towards a deeper solution. For example, the maturity of mass transfer technology, the improvement of efficiency and reliability; higher quality LED chips and reliability, etc., are continuously improving the technical difficulty structure of COB.
COB screens have been verified
On the other hand, the first batch of COB large screens has been used for more than 5 years, and the effect and reliability have been widely verified and tested. As a high-end technical solution, COB is deeply rooted in the hearts of the people and has become the benchmark for high-end choices in the market.
COB has a higher production rate because of no SMT process
COB technology saves part of the manufacturing process. It has higher production efficiency.
The industrial chain of COB is also shorter.
From LED chip epitaxy to end products, it no longer needs the three links of “upstream wafer, midstream packaging, and downstream LED display” in the traditional display market, but has become ” The packaging process has been integrated by display manufacturers; or the upstream packing companies directly produce COB display modules.
This has greatly changed the development of the industry and the distribution of core technicals and has a great impact on the future technology route choosing and development.
The cost advantage of COB will become more and more obvious
The cost of P1.2 products using COB technology and SMD technology is evenly matched. By P0.9mm display, the comprehensive cost of COB has been far lower than that of SMD. The smaller the pixel pitch, the more obvious the comprehensive cost of COB. Especially below P1.0mm, the technical advantages of COB will be more obvious.
However, with the gradual maturity of technology and continuous improvement of technology, the yield rate of COB has increased rapidly, and its cost has also decreased rapidly with the increase of batch production.
Because COB technology saves part of the manufacturing process, it has higher production efficiency.
COB positions mid-to-high end
COB packaging products are positioned as mid- to high-end products. At present, they mainly for LED display within P1.6mm, and mainly for P1.2mm displays. From the perspective of the proportion of each pitch, the advantage within P1.2 is stronger.
COB technology is better at highly integrated packaging with high pixel density. The smaller the pitch, the more obvious the comprehensive cost advantage of COB products.
Does MIP have long-term competitiveness compared with COB?
MIP is a transitional technology?
At present, most enterprises basically follow the dual-line development of SMD and COB.
Looking at MIP technology in more popular application products, such as P1.2, P1.5, and even P3.0, its advantages are still big.
Micro-pitch LEDs are mainly aimed at the mid-to-high-end market, and they are not very sensitive to cost. Instead, they care more about product reliability and brand reputation.
In the future, as the micro-pitch LED market expands, cost competition must be one of the key directions. However, the applications for micro-pitch LEDs are still based on ultra-high-end demands such as 8K, and consumer markets such as all-in-one display. These demands are still market sensitive to the brand even after the cost has fallen sharply.
Therefore, there is still huge suspense about whether MIP will become a real market competitiveness.
MIP package is suitable for small business
The core advantage of MIP package is “flexible”. This is the excellent path” to enter the micro-pitch LED market for those display enterprises, especially those who do not master the COB technology, and who are not able to enter the chip-level packaging process market.
MIP encapsulation for SMT technology-based small and medium-sized LED direct-view display enterprises is easy to master, and has a cost-friendly, flexible production organization.
MIP is currently only suitable for large-size LED screens
MIP technology is only suitable for the large-size direct-view LED display market, while the micro LED is also aimed at small and medium-sized display scenarios such as near-eye micro-displays, wearables, and vehicles. The latter is unlikely to use the MIP structure to solve the problem of mass production—that is, the further maturity and progress of mass transfer technologies such as one-time larger-scale integration (far exceeding the COB level of large-size LED display), which are micro, small and medium-sized microdisplay basis.
MIP advantage will decline in the future
The advantage of MIP is the compromise route.
At present, many advantages of MIP are realized through a compromise route: for example, low requirements for reliability of mass transfer, low requirements for detection and repair, etc. These advantages exist because the mass transfer technology is not yet mature and reliable; because the defect rate of actual large-scale integrated packaging is still relatively high (more than 1/100,000). If these technical issues are resolved, the advantage of MIP will decline.
The development of small-size COB will promote the development of large-size display COB.
If the small and medium-sized micro LED display technology can be successfully commercialized and matured, then its technology applied to large-sized “advanced CELL” LED display module products. It will inevitably bring about another leap-forward upgrade of COB technology: including Both cost and reliability competitiveness will be further improved. At that time, the advantage of MIP in the micro-pitch LED direct-view display market may decline.
Future cost reductions for MIP are limited.
On the other hand, the method of MIP to reduce the cost problem is also very unique: a single lamp bead package improves the “yield rate”, which is the key point of cost advantage in the ratio of MIP and COB. However, if the COB yield increases, that is, the defect rate drops significantly, then this advantage will be significantly diluted. ——In the micro-pitch market, the real cost problem comes from “more pixels”: the smaller the pitch, the more pixels per unit area, and the higher the cost. Even with the mature SMT (surface-mount technology) used in the MIP display production, it is difficult to achieve a breakthrough in cost in this regard.
MIP has an obvious advantage over COB in P1.2~P3.0mm LED display
Of course, if you jump out of the framework of micro-pitch and look at MIP technology in more popular application products, such as P1.2mm, P1.5mm, and even P3.0mm, its advantages are still huge. MIP is almost the “optimal solution” for mini/micro specification LED chips applied to LED direct-view displays. Because of the larger pitch, the cost of applying COB technology to these products is much higher. COB technology is better at highly integrated packaging with very higher pixel density.
MIP may not compete with COB in the field of fine pitch, but replace IMD and SMD
From the perspective of the dynamic development of technology, with the progress of mass transfer, the improvement of LED chip reliability and performance redundancy, there is still a lot of room for improvement in COB packaging.
The competition between MIP and COB is not only a contest under the existing technical conditions, but also a contest under the continuous technological progress in the future – MIP is a new industry breakthrough. Who can guarantee that COB will not make further breakthroughs in the future?
The greater significance of MIP is to replace IMD and SMD on small pitch and micro pitch, rather than to compete with today’s high-end technology COB.
MIP’s CURRENT DEVELOPMENT
MIP is developing rapidly
It is precisely because of MIP’s advantages over COB and SMD， that this technology, although later than COB and IMD, has been developing rapidly since the second half of 2022.
At the beginning of 2023, domestic companies including Natiosntar, Kinglight, and Xxinying also brought MiP mass-produced products to the international ISE exhibition, which focuses on indoor fine-pitch P0.7-P1.2mm high-end fixed and private cinema screens.
As one of the earliest supporters and inventors of IMD technology, Nationstar, launched MiP devices in ISE 2023, including MiP-C0404 with a size of 0.40 * 0.40*0.23 mm, which can be adapted to a wide range of pixel pitch LED wall product applications; and MiP-C0606FTP device adopts a common cathode design, which can be adapted to pixel pitch from P1.5 to P0.6, and is suitable for indoor ultra-high-definition display scenarios. Two types of MIP can meet the small-pitch and micro-pitch LED direct-view display of most of the needs.
MIP display applications
At the beginning of 2023, Sony’s new series of high-brightness and immersive Crystal LED displays attracted attention again. Before the launch of these two products, Sony’s commercial-oriented Crystal B series and C series launched in 2021 also received industry attention. What is worth mentioning behind this is that both products use MiP (Micro LED in Package) technology, and it is said that the devices may come from Seoul Viosys.
At present, MIP LED is mainly used for P0.7, P0.9 and P1.2 pitch high-end displays. And this part of the market is the area where MiP will exert its strength in LED displays.
MiP uses a suitable product form to make LED displays more advantageous in terms of cost and benefit, which is the key to the landing of MiP products. Of course, the final development still depends on the willingness of markets and the speed of the LED display brands.