PCB (Printed Circuit Board) has been the first choice for Mini LED backplanes for a long time. But as Mini LED chips become smaller and smaller, glass is gradually replacing PCBs.
Recently, BOE revealed the new progress of Mini LED on the investor interactive platform. BOE said that the company is optimistic about the prospects of Mini LED products and has deployed glass-based Mini LED related products. The company's glass-based Mini LED is expected to be mass-produced in the second half of this year. TCL Technology (000100) said in an interview with a reporter from "China Electronics News" that the glass base will greatly reduce production costs, and its Mini LED backlight products currently use this material.
It is not easy to replace PCB. Mini LED backlight technology has become more and more popular in the past two years, attracting many companies to deploy, and even some manufacturers have made it clear that they will achieve mass production of Mini LED backlight products this year. Chuancai Securities pointed out in a report in April this year that 2020 is the first year of mass production of "Mini LED backlight + LCD" products, and the application of Mini LED technology is now economical.
While welcoming great attention, Mini LED backlight has also experienced the game and update of various technical routes. Among them, the important production material of Mini LED backlight-substrate is facing a dilemma. LED packaging manufacturers mainly promote PCB, and panel manufacturers support glass substrate solutions. It is worth mentioning that in the past, the substrate material of Mini LED backlight products has always been PCB.
An LED packaging manufacturer said in an interview with a reporter from China Electronics News that the reason why the Mini LED backplane material was the first to use PCB was mainly because the LED packaging factory was the first to develop and produce Mini LEDs. Involved in this field. The LED packaging factory is more proficient in PCB substrate technical solutions and can introduce industrialization more quickly. At the same time, because the PCB substrate technology is more mature and the supply chain is relatively complete, the yield rate of PCB-based Mini LED products is much higher than that of glass-based Mini LED products at this stage.
Relevant person in charge of Ruifeng Optoelectronics (300241) also told reporters that there are still some technical bottlenecks in glass substrates that have not yet been overcome, and PCB substrate solutions can be quickly intervened, so PCB-based Mini LED products will be shipped sooner. It seems that it is not easy for Mini LED backlight to achieve the technological leadership of the glass substrate solution. However, people in the industry still believe that glass will gradually replace PCB and become the first choice for Mini LED backlight backplanes.
PCB is limited by its own performance. Today, the Mini LED market is not only a piece of fat in the eyes of LED packaging manufacturers, but also a battleground for panel manufacturers. After panel manufacturers enter the Mini LED market, the reasons for innovatively adopting glass substrates are similar to the reasons why LED manufacturers choose PCB. "Glass substrate has always been the main material for the production of LCD panels. For panel manufacturers such as BOE and TCL Huaxing, glass substrates are chosen as the Mini LED backlight for ‘quick start’." said Liu Tun, senior analyst at CCID Consulting.
In addition to adaptability factors, what really determines the choice of substrate material is cost and performance. Industry insiders believe that glass-based Mini LEDs have lower cost and better performance. The improvement of the display effect not only puts forward higher requirements on the performance of Mini LED backlight, but also puts forward new challenges to the processing accuracy of the backplane's thickness uniformity, flatness, and alignment.
"Today, Mini LED chips are becoming smaller and smaller. Mini LEDs will have more chip soldering per unit area, and the heat intensity will be higher than that of current LED backlight products. PCB substrates are limited by their own heat dissipation. , There is a problem of warpage and deformation, so it is more and more difficult to transfer Mini LED chips directly to the PCB substrate.” Liu Tun analyzed that glass materials have good heat dissipation and low thermal expansion rate, which can be effectively applied to high-density Mini LED welding, and meet the complex wiring needs. This provides more dynamic dimming of the display partitions for Mini LEDs, and improves the display effect. In addition, the glass substrate has high flatness and good rigidity. When multiple sets of backlight units are spliced, the glass substrate can meet the needs of high-precision splicing and reduce the black seams caused by splicing, so as to better realize the production of large-size Mini LED products.
"Glass substrates are not only superior to PCB substrates in terms of flatness and stability, but also have advantages in cost." An LED packaging manufacturer said that due to the current gap in stability and accuracy of domestic PCB substrates, it cannot meet the requirements of Mini LEDs. The performance requirements of PCB substrates, the PCB substrates required by Mini LEDs need to be imported from Japan, South Korea and other countries and regions, and the cost remains high. "Especially in March and April of this year, the price of imported PCB substrates has increased a lot." The relevant person in charge of the packaging manufacturer said.
Qiu Yun, deputy director of the technical planning department of the BOE Display and Sensor Business Group Organization, said that, for example, the 6-layer 2-layer and 8-layer 3-layer PCB substrates required for Mini LED backlights are basically not available in domestic batches and can only be imported at high prices. The relevant person in charge of TCL pointed out in an interview with a reporter from "China Electronics News" that after years of running-in, glass substrates are now relatively mature in equipment and technology, and the supply of glass materials is relatively stable and the cost is relatively low. Therefore, using glass instead of PCB as the LED backplane can not only greatly reduce manufacturing costs, but also help stabilize manufacturers' confidence. According to the relevant person in charge of TCL, compared to the PCB-based Mini LEDs currently promoted by OEMs, the glass-based TFT drive cost is lower when the display effect is the same.
The glass substrate has yet to be tested by the market. A few days ago, BOE revealed the new progress of Mini LED on the investor interactive platform. BOE said that the company is optimistic about the prospects of Mini LED products and has deployed glass-based Mini LED related products. The company's glass-based Mini LED is expected to be mass-produced in the second half of this year. TCL said that TCL Huaxing began to deploy glass-based Mini LEDs in 2018, and the technology is now relatively mature. In the future, whether Mini LED backlight products are to be applied on a large scale in TV, tablet, laptop and other markets, TCL Huaxing will definitely choose glass substrates.
When panel manufacturers such as BOE and TCL Huaxing established glass substrate Mini LED backlight as the mainstream direction of the future market, large packaging manufacturers including National Star Optoelectronics (002449), Ruifeng Optoelectronics, Jufei Optoelectronics (300303), Jingtai Optoelectronics, etc. Did not give up the efforts in glass substrate technology. According to Wang Sen, general manager of National Star Optoelectronics (600184) Co., Ltd., its glass-based Mini LED backlight related products have been shipped in small batches, and the future trend will follow the mainstream of the market. Ruifeng Optoelectronics also stated in the latest "Investor Relations Activity Record" that the company's Mini LED research projects include both glass substrates and PCB substrates.
However, TrendForce analyst Chen Shuxun pointed out in an interview with a reporter from China Electronics News that both PCB substrates and glass substrates have their own advantages and disadvantages. Although the advantages of glass substrates are outstanding, their disadvantages such as fragility are also obvious. Let us wait and see what kind of substrate can become the major trend of Mini LED backlight in the future.
