The era of Mini/Micro LED displays has arrived. However, to achieve widespread adoption of micro-pitch displays, yield and cost control are crucial for mass production. The best approach currently to ensure optimal yield and cost is by focusing on packaging technology.
While COB (Chip on Board) products and technology have already gained a first-mover advantage, MiP (Micro in Package) has been rapidly entering the market in 2023. This accelerated adoption by leading manufacturers has ignited intense debates in the industry about the future of packaging approaches.
In comparison, COB, as a chip-on-board packaging method, has advantages in reliability and reduced pixel spacing. However, it requires investment in new equipment, resulting in higher overall costs. In contrast, MiP is compatible with traditional production equipment, achieving comprehensive cost control. Both methods have their merits. But what are the market positions and future prospects of MiP and COB technologies? Which do leading manufacturers prefer?
In light of this, Digital Audio and Visual Engineering Network organized a micro-interview with the theme “MiP vs. COB: Who will be the mainstay for future Micro LED?” We invited representatives from top industry manufacturers, including Leyard, Unilumin, Cedar Electronics, AET, HCP Technology, and Kinglight for discussions.
Q1: Differences and Advantages of MiP and COB Technologies
Unilumin: Many manufacturers refer to MiP as “Mini in the package,” but few have mass-produced the genuine “Micro in the package.” MiP’s strength lies in miniaturization: smaller packaging sizes while maintaining consistent brightness and color differences. It has strong industry continuity, allowing for seamless product replacement without altering existing electronic structures, significantly enhancing product performance.
Leyard‘s China Product Director, Sun Zheng: MiP boasts advantages such as uniform lighting, high uniformity, and no Mura effect. It can be directly tested and sorted without costly rework, reducing testing challenges. MiP is highly compatible with large-sized Micro LED mass production and is favored by end-display manufacturers. In scenarios with smaller pixel pitches and larger display sizes, MiP can overcome bottlenecks like yield, ink color consistency, uniformity, inspection and rework, and cost, making it the ideal choice for Micro LED display production. Beyond technical merits, MiP aligns with the existing LED display process, indicating its high compatibility across processes and technologies.
Chief Operating Officer of Changchun Cedar Electronics, Ji Fengqiang: The market differentiates MiP into two types: packaging-level and chip-level. Packaging-level MiP, represented by brands like Kinglight, remains an extension of SMT technology. In contrast, chip-level MiP is dominated by international brands like Seoul Semiconductor and Samsung. The distinction between packaging-level MiP and COB is actually between SMT and COB packaging. COB leads in terms of reliability and stability. COB’s direct chip-to-board method reduces costs significantly compared to packaging-level MiP. MiP primarily operates in the Mini LED realm, catering to commercial displays, XP filming, and consumer domains. It’s less suited for government and medical applications and can’t fully penetrate the Micro LED market due to its pixel pitch limitations. Thus, packaging-level MiP represents an extension of existing capabilities, not the future’s broad landscape.
Chip-level MiP essentially rearranges RGB chips. Its process still involves pick and place or mass transfer, generally in line with COB’s future tech trajectory. However, its high cost and uncertain mass production capabilities make bulk supply challenging in the short term. In the Micro LED domain, it will run parallel to COB until the market and users make their final choice. COB is the primary tech for Mini LED and the gateway to Micro LED.
AET: MiP and COB represent the two leading techniques in the Mini/Micro LED display industry. MiP is a unique encapsulation technique based on Micro LED, while COB mainly revolves around chip-level integrated packaging for Mini LED.
MiP has evolved from well-established small-pitch display products. It fundamentally combines Micro LED with discrete components. This approach breaks down large display panels into individual encapsulated parts, delivering improved yield rates and cost efficiencies. It stands out with superior quality, high reliability, enhanced protection, strong compatibility, and the ability to mix bins for consistent display quality.
COB technology aims to simplify the packaging structure of ultra-fine electronic components and enhance product stability. It excels in areas like ultra-high contrast, ultra-wide viewing angles, extreme stability, and superior heat dissipation. The shift from point light sources to planar ones with COB has been widely recognized and validated.
HCP Technology‘s R&D Director, Huang Zhiqiang: MiP packaging technology emerged as a transitional solution when COB faced yield challenges. By adding an encapsulation process and enlarging solder pad pins, MiP reduces substrate precision requirements and improves die-bonding yields. In the short term, MiP might enjoy certain cost advantages due to its higher back-end yields and potentially faster entry into the Micro realm than COB. Other merits include cost-saving by using wafer-level processing and the ability to mix crystal and bins for better light and color uniformity.
However, MiP demands more sophisticated upstream processes. The additional encapsulation step is a double-edged sword—it affects yield and raises costs. For downstream screen manufacturers, MiP can mitigate massive capital expenditures for line equipment replacement. However, increased upstream costs would eventually trickle down to them, making MiP a challenging choice.
COB packaging has simplified both processes and materials, resulting in higher production efficiency and theoretically the lowest cost. It’s more suited for micro-pitch, high-pixel-density integrated packaging. In the future, with advancements in mass transfer equipment, substrate precision, and Micro LED chips, COB’s yield rates will rise, unlocking more significant cost-saving potential.
Q2: Market Positioning and Future Prospects of MiP and COB Technologies in Commercial Development
Unilumin: The real industrial mechanism of MiP lies in the miniaturization of processes. It consolidates the industry chain upstream, drastically improving the return on investment. Anything COB achieves, MiP can also accomplish. MiP has robust technology continuity, enabling rapid industrial substitution. From rental, outdoor/indoor displays, specialized commercial displays to channels, MiP offers a seamless transition, catering to product miniaturization and addressing SMT challenges. Both COB and MiP work in tandem, aiming to replace SMD in the industry. The market will ultimately determine the dominant approach.
Leyard’s China Product Director, Sun Zheng: Cost is always key for the industrial application of innovative technologies. The central contest between COB and MiP revolves around who can better achieve cost reductions while enhancing Micro LED quality. Leyard believes that, as MiP uses mass transfer equipment, smaller chips theoretically increase efficiency. Smaller chips not only pave the way for displays with smaller pixel pitches and smaller size applications but also reduce material costs, pointing towards a future trend. In terms of performance metrics, MiP outshines COB in aspects like ink color consistency, color uniformity, and repairability. Therefore, MiP’s trajectory aligns with the commercial development process of Micro LED. Its high performance and equipment compatibility ensure market reception and features fast product iteration and significant cost reduction potential.
Cedar Electronics’ COO, Ji Fengqiang: Whether manufacturers adopt packaging-level MiP or COB depends on their resources and capabilities. Packaging-level MiP may find market opportunities before COB achieves optimal scale economies. However, with major COB players like Zhaochi and Gaoke entering the scene, this time window might be significantly narrow. Given uncertainties in project delivery and post-sales services, market players might opt for solutions tailored to specific projects, with bulk applications facing challenges in confidence.
Chip-level MiP is still in its conceptual and small-batch phase. High costs and not-so-impressive current display quality limit its market appeal, necessitating further refinement. This year, SONY’s strategic shift to use Mini chips in COB signifies that we’re still in the Mini LED battleground. The large-scale market application of Micro LED demands more time and preparation.
AET: In the short term, COB’s mature application in the Mini LED domain, backed by its remarkable display effects, high flatness, and consistency, positions it as the industry standard. In the long run, with the trend of decreasing pixel pitch, MiP will guide the wind’s direction in Micro LED applications. Given its display quality, mature processes, cost benefits, brightness, low power consumption, compatibility, and ability to mix bins for consistent display quality, MiP will capture more opportunities in the Micro LED era.
HCP Technology’s R&D Director, Huang Zhiqiang: Both target primarily the indoor micro-pitch market, with the main distinction being that MiP offers a broader client base as a bead form.
Future market applications hinge on costs. Currently, MiP might have advantages below P0.9, but for P1.2 and above, COB’s yields make it more cost-effective than MiP. COB’s structural and process simplicity ensures it’s the cost-optimal solution when yields are assured.
Q3: Which technological direction does your company lean towards and why?
Unilumin: Unilumin pursues both MiP and COB concurrently. This strategic approach allows us to cater to diverse customer needs, broadening our market applications. MiP and COB aren’t direct competitors; they complement each other. Unilumin aims to provide varied solutions through this dual-track strategy.
Leyard’s China Product Director, Sun Zheng: We believe MiP is a pivotal technological direction. Firstly, MiP has inherent advantages over COB. Its compatibility with large-scale Micro LED production, acceptance by display manufacturers, and unique advantages in micro-pitch, large-sized displays make it the best choice for Micro LED screen production.
Cedar Electronics’ COO, Ji Fengqiang: As an entity under the Changchun Institute of Optics and Fine Mechanics, Cedar Electronics represents China’s autonomous innovation in the LED industry. We’ll steadfastly follow the COB route, dedicating ourselves to technical and process innovations and training professionals. With systematic planning from Mini LED to Micro LED, we’re confident of competing globally, earning international respect and trust for Chinese LED tech and products.
AET: AET focuses on pioneering R&D, establishing a technological ecosystem that concurrently progresses with MiP, COB, QCOB, and more. By leveraging the complementary strengths of various technologies, we aim for breakthroughs in multiple domains, continually exploring the potential of Mini/Micro LED displays.
HCP Technology’s R&D Director, Huang Zhiqiang: We have always maintained parallel development in both COB and MiP technologies, believing they’ll converge in the future, particularly in the Micro LED domain.
Kinglight Packaging R&D Center’s R&D Director, Yan Chunwei: Kinglight primarily leans towards MiP. Currently, COB has several pain points, which MiP effectively addresses. MiP offers better display quality, color consistency, higher yields, and lower costs, making it an essential future technological direction.
Conclusion
This interview highlights that even among frontline manufacturers, the debate on the merits of MiP vs. COB continues. Generally, manufacturers appreciate MiP for its equipment reusability and technological maturity, while they value COB for its growth potential. Many choose a dual-track approach, while others firmly pick a side. Regardless, there’s a unanimous acknowledgment: MiP’s significance is undeniable at present. COB’s cost reductions require further breakthroughs, and the large-scale market application of Micro LED remains a considerable challenge ahead.
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