In the field of displays using LED chips as light sources, LED packaging technology directly impacts various aspects of display performance and usability. In the high-definition display sector, two packaging technologies currently stand out: COB vs. POB.
Which of these two packaging technologies is better? After reading this article, you will have your answer.
What is COB Packaging Technology?
COB packaging technology is a method that enables the batch bonding of multiple LED chips onto a single substrate, followed by the encapsulation of the substrate with the bonded LED chips.
This LED packaging technology significantly reduces the bonding space required for LED chips, with the distance between chips able to reach less than 1mm. As a result, COB packaging technology is primarily used in the production of small-pitch LED screens.
What is POB packaging technology?
POB packaging technology involves first packaging individual LED chips, then bonding the packaged LED chips to the substrate. The process of bonding the packaged LED chips to the substrate primarily involves two types of technology: flip-chip SMD technology and CSP technology.
Flip-chip SMD technology: Flip-chip SMD technology involves flipping the packaged LED chips and bonding them, connecting the electrodes of the packaged LED chips to the substrate, and then soldering the substrate to the base.
CSP technology: CSP technology directly connects the electrodes of the packaged chips to the substrate without the additional substrate size from flip-chip SMD technology, enabling smaller LED chip spacing.
COB vs. POB
Production Process
COB technology involves denser LED chip packaging, requiring higher-quality LED chips and stricter process control. The production process for COB technology is more complex, resulting in lower yield rates compared to POB technology.
In contrast, POB technology has a simpler production process with lower requirements for substrate precision, achieving higher yield rates.
Performance
Due to the integration of multiple LED chips, COB LED screens offer higher overall brightness, higher contrast, more uniform color reproduction, and better display quality.
POB technology-manufactured displays, due to the characteristics of individual LED chip packaging, cannot achieve the small spacing between LED chips seen in COB technology, resulting in images that are not as detailed or clear as those produced by COB technology, with lower brightness and color contrast.
Technical Advantages
COB packaging technology bonds LED chips at a sufficiently high density, increasing the lumen density of COB LED screens.
In COB packaging technology, the LED chip electrodes are directly connected to the substrate, simplifying the interconnecting circuits between LED chips and reducing power consumption due to circuit resistance. As a result, COB LED screens feature high brightness and energy efficiency.
In POB technology, CSP technology is used for chip bonding. Although it shares the direct connection between LED chip electrodes and the substrate with COB technology, the narrow spacing and insufficient pad area in the final CSP technology product may lead to issues such as uneven color distribution on the display screen.
In contrast, flip-chip SMD technology enables mass production with high yield rates and lower production costs. Therefore, most POB technology on the market currently uses flip-chip SMD technology for chip bonding. POB displays assembled using flip-chip SMD technology have slightly lower display performance than COB displays, but are more cost-effective.
Cost
POB technology production is simpler, as it can utilize existing SMD technology production lines without requiring additional technical development.
The POB technology production supply chain is highly mature and complete, with lower production costs, lower process requirements, higher yield rates, and further cost savings.
The production supply chain for COB technology is relatively less mature. Due to its higher requirements for process and quality, the equipment and materials capable of meeting COB technology standards are relatively scarce, and the number of LED manufacturers capable of precisely executing the process is also limited.
Additionally, COB technology has a slightly lower yield rate than POB technology and consumes more materials, resulting in higher overall production costs.
Maintenance
Since POB technology encapsulates individual LED chips, if a single LED chip becomes damaged in the future, you can attempt to repair the LED module at home using tools and replace the LED chip. Its maintenance is relatively straightforward.
In contrast, COB technology integrates multiple LED chips onto a single substrate, with smaller spacing between chips and higher precision, making manual repair of LED chips on-site impossible.
In such cases, you must promptly replace the LED module with a spare to ensure the LED display screen operates normally, then return the faulty LED module to the manufacturer for repair.
Applications
Both COB and POB technologies are primarily used in displays for medium-sized and small devices. Considering display quality, COB technology produces higher-resolution, more detailed displays with vibrant, lifelike colors, making it more suitable for high-end display applications.
While POB technology does not match the display quality of COB technology, its overall display performance is sufficient for everyday viewing. Due to its high cost-effectiveness, POB technology is highly popular in the mid-to-low-end display market.
COB vs. POB: Which is better?
POB technology displays are cheaper, but their image quality is only suitable for everyday viewing and cannot be used in more high-end, precise display applications.
COB technology is more expensive than POB technology, but displays produced using COB technology offer superior image quality and viewing experience.
In reality, there is no single “best” technology; the choice depends on your specific needs. If you only need it for everyday use such as meetings or presentations and do not require high image precision, then POB technology is the best choice for you.
If you need to purchase a display for movie playback, gaming, or other high-end display scenarios, POB technology may not be suitable for you. In such cases, COB technology is the better choice.
