From Lamp to Micro LED display packaging development trends | Part-2
Continuing with the last post, we will continue further. In recent years, with the continuous development of the market economy, there are many high-rise buildings in the city, and transparent LED displays have been widely used in fields such as urban glass curtain wall landscape lighting and architectural art improvement. Many clients are very unfamiliar with the Mustang LED display.
LED packaging development trends
The resolution of the LED display is determined by the size and spacing of the packaged components. Under the limitations of traditional technology, the spacing between LED devices is large, resulting in low resolution. It is only suitable for long-distance viewing outdoors and is difficult to use indoors.
Therefore, in the past, in the field of indoor display, LCD, DLP (Digital Light Processing) splicing walls and projection technologies occupied a dominant position.
With the advancement of technology and the expansion of upstream production capacity, the cost of small-pitch displays has gradually declined, and it has a basis for commercial application, making LED displays gradually compete with traditional display technologies in the indoor display field.
With the advancement of LED SMD Screen chip packaging technology, display drive control technology and display assembly and manufacturing processes, the resolution of LED displays has been greatly improved. The pixel center distance of indoor high-density LED displays continues to make breakthroughs.
Compared with DLP, LCD and other display products, the small-pitch LED display has the characteristics of high-definition display, high refresh rate, seamless splicing, good heat dissipation system, easy disassembly and assembly, etc.
Even when viewed at a relatively close distance, the display screen is ultra-clear and flicker-free. No graininess. The seamless, high-contrast, high-resolution COB LED and Micro LED displays that have appeared in recent years have made traditional LED display customers shine.
In the next few years, indoor high-density LED displays will continue to encroach on the splicing wall market and become the mainstream display medium for indoor high-density large screens. They will be used in commercial displays, command and control centers, high-end auto shows, studio conference centers, cinemas and other indoor display venues. Has a wide range of applications.
In terms of outdoor applications, in recent years, with the improvement of outdoor surface-mount LED packaging technology and the improvement of outdoor module protection level, the pixel pitch limit of outdoor full-color screens is constantly being refreshed. The development of LED displays towards high resolution has become an irreversible trend. Miniaturization of LED devices (chips) and high-density integration of modules are its key technologies.
However, its development mainly relies on flip chip packaging technology and COB packaging. Technology and the development of Micro LED packaging technology.
COB package
As people have higher and higher resolution requirements for indoor and outdoor LED displays, if traditional LED devices are still used to assemble LED displays, on the one hand, because LED display devices are getting smaller and smaller.
The process is difficult, the sharp increase and low yield rate lead to an increase in the cost of a single LED device. Secondly, small-size LED devices also require very high precision of patch equipment. Thirdly, the smaller the point spacing of the LED display, the more required patch the number of LED devices has increased geometrically, greatly reducing the manufacturing efficiency of LED screens.
The COB display module uses integrated packaging, eliminating the need for a single LED device to be packaged and then patched, which can solve the above problems. Chip on Board is a structure in which multiple LED chips are directly mounted on a heat dissipation PCB substrate to directly conduct heat.
Therefore, COB packaging requires close cooperation between upstream, midstream and downstream enterprises to promote the large-scale application of COB LED displays. As shown in Figure 3, it is a COB integrated package LED display module.
The front is an LED light module forming pixels, and the bottom is an IC driver component. Finally, the COB display modules are spliced into an LED display screen of the designed size.
COB integrated packaging can not only reduce bracket costs and simplify the LED screen manufacturing process, but also reduce chip thermal resistance and achieve high-density packaging. The LED display screen that uses COB packaging expands the heat dissipation area of the device to a certain extent, making it easier for the heat generated to spread to the outside world.
In terms of cost, compared with traditional packaging methods, COB LED display modules can save device packaging costs in practical applications. In a display system with the same functions, the overall cost of a display module using COB LED is more than 30% less than that of a traditional display panel, which is of great significance for the widespread promotion of COB LED displays.
From the application side, COB LED display modules can provide display application manufacturers with a simpler and faster installation and production method, greatly improving production efficiency.
In terms of production preparation, existing mass production manufacturing technology and production equipment can well support the mass production of COB LED display modules, and most importantly, they can maintain a high yield rate.
With the arrival of 5G
The market has urgent demand for large-size display applications of ultra-high-definition 4K and 8K. The development of LED towards fine-pitch displays is an inevitable trend.
COB technology continues to heat up with its performance advantages, and the impact of the development of this technology on the industry market structure has also become the focus of attention in the industry. The birth of flip-chip COB has raised COB technology to a new level.
Therefore, from the perspective of performance, cost and application, COB will become the mainstream direction of LED display packaging in the future.
However, COB display screens have not yet been mass-produced on a large scale. The main reasons are that the one-time pass rate of packaging is not high, the contrast is low, and maintenance costs are high. In addition, its color uniformity is far inferior to that of SMD Screen devices that use spectroscopic and color separation.
Display
Existing COB packages still use formal chips, which require die bonding and wire bonding processes. Therefore, there are many problems in the wire bonding process and the process difficulty is inversely proportional to the pad area. Once the flip-chip chip technology matures and the wire bonding process of the chip is omitted, the first pass rate of chip assembly will be greatly improved.
In addition, it is also a good direction to improve the first pass rate of packaging by reducing the area of a single COB module. As for the problem of display uniformity, it can be improved by improving the consistency of the upstream chip and the single-lamp point-by-point correction technology of the COB display module.
In short, the problems faced by COB integrated packaging technology require the joint efforts of the upper, middle and lower reaches of the industry to solve. Micro LED Display is a new generation of display technology. Its LED structure is thinned, miniaturized and arrayed, making its volume approximately 1% of the size of mainstream LEDs.
Each pixel can be addressed and by driving light alone, the pixel spacing is reduced from millimeter level to micron level, thus theoretically reaching ultra-high resolution of more than 1500 ppi or even 2000 ppi.
Micro LED inherits the advantages of LED SMD Screen such as low power consumption, high brightness, ultra-high resolution, color saturation, fast response, ultra-power saving, long life, and high efficiency. Its power consumption is about 10% of LCD and OLED. 50%.
Therefore, Micro LED is regarded as a new generation of display technology that may disrupt the industry. Micro LED displays have only gradually entered the market in recent years after more than ten years of technology accumulation. It is currently developing in two directions.
One is represented by Apple and focuses on small-size, wearable Micro LED displays. The other is represented by Sony and focuses on medium and large-sized displays. But no matter what field it is used in, the CLEDIS bigger problem for Micro LED packaging technology is how to ensure “high yield (more than 99.9999%) and transfer rate” during the mass transfer process of LED chips in the die-bonding process.
Sony’s, launched at in the United States in 2016, uses a “modular splicing” approach to improve the transfer yield, that is, by reducing the pixel density per unit area to make small-sized Micro LED display modules, and finally splicing them into a large screen.
Micro LED packaging technology is currently in a stage of rapid development and requires a lot of investment in Pakistan. The core technology is mainly mastered by foreign companies. Therefore, Mustang LED packaging manufacturers need to speed up the deployment of Micro LED technology.
LED display devices have experienced more than 6 years of development in dot matrix modules, direct plug-in, sub-surface mount, and surface mount three-in-one packaging, etc. And have continuously moved to new levels in terms of color performance, resolution, reliability, etc. And have gradually become popular in large-scale applications.
Outstanding advantages in the field of screen display. As LED displays develop toward high resolution, LED device packaging faces huge challenges in the development of miniaturization, integration, high reliability, and high brightness. The development of COB LED packaging and Micro LED packaging technology will also bring LED device packaging brings new technological innovations.