Glass is gradually replacing PCB as the preferred option for Mini LED backlight backplates

For a long time, PCB (printed circuit board) has been the preferred choice for Mini LED backplanes. But as Mini LED chips become smaller, glass is gradually replacing PCBs.

Recently, BOE revealed the new progress of Mini LED on its investor interaction platform. BOE stated that the company is optimistic about the prospects of Mini LED products and has laid out 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 stated in an interview with China Electronics News that glass based materials will greatly reduce production costs, and currently all of its Mini LED backlight products use this material.

Replacing PCBs is not an easy task

The demand for Mini LED backlight technology has been increasing in the past two years, attracting many companies to layout their products. Some manufacturers have even explicitly stated that they will achieve large-scale 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 currently economically viable.

While Mini LED backlight has received great attention, it has also undergone a game and update of various technological routes, among which the important production material of Mini LED backlight - substrate - is facing a dilemma. LED packaging manufacturers mainly promote PCB, while panel manufacturers support glass substrate solutions. It is worth mentioning that in the past, the substrate material for Mini LED backlight products was mainly PCB.

A certain LED packaging manufacturer stated in an interview with China Electronics News that the reason why Mini LED backplate material was first selected as PCB is mainly because LED packaging factories were the first to develop and produce Mini LED, and panel manufacturers had not yet been involved in this field. LED packaging factories are more proficient in PCB substrate technology solutions and can quickly introduce them into industrialization. At the same time, due to the more mature technology of PCB substrates and relatively complete supply chain, the yield rate of PCB based Mini LED products is much higher than that of glass based Mini LED products at present.

The person in charge of Ruifeng Optoelectronics also told reporters that there are still some technical bottlenecks in the glass substrate that have not been overcome, and the PCB substrate solution can be quickly intervened, so the PCB based Mini LED products will be shipped earlier.

It seems that achieving technological leadership in glass substrate solutions for Mini LED backlighting is not an easy task. However, some industry insiders still believe that glass will gradually replace PCB and become the preferred choice for Mini LED backlight backplates.

      PCB is limited by its own performance

Nowadays, the Mini LED market is not just a piece of fat in the eyes of LED packaging manufacturers, but also a battleground for panel manufacturers. The reason why panel manufacturers innovatively adopt glass substrates after entering the Mini LED market is similar to the reason why LED manufacturers choose PCBs.

Glass substrate has always been the main material for LCD panel production. For panel factories such as BOE and TCL Huaxing, choosing glass substrate as Mini LED backlight is' easy to get started ' According to Liu Hao, a senior analyst at CCID Consulting.

In addition to adaptability factors, cost and performance are also the true determinants of substrate material selection. Industry insiders believe that glass based Mini LEDs have lower costs and better performance.

The improvement of display effect not only puts higher demands on the backlight performance of Mini LED, but also poses new challenges to the processing accuracy such as thickness uniformity, flatness, and alignment of the backplane.

Nowadays, Mini LED chips are becoming smaller and have more chip soldering per unit area, resulting in higher heat density compared to current LED backlight products. Due to its limited heat dissipation, PCB substrates suffer from warping and deformation, making it increasingly difficult to directly transfer Mini LED chips onto PCB substrates Liu Hao analyzed that glass materials have good heat dissipation and low thermal expansion rate, which can be effectively applied to high-density Mini LED soldering and meet complex wiring needs. This provides more dynamic dimming for Mini LED display zones, improving the display effect. In addition, the glass substrate has high flatness and good rigidity. When splicing multiple backlight units, the glass substrate can meet the high-precision splicing requirements, reduce the black seams generated by splicing, and better achieve the production of large-sized Mini LED products.

      Glass substrate has lower driving costs

Glass substrates are not only superior to PCB substrates in terms of flatness and stability, but also have cost advantages. A certain LED packaging manufacturer stated that due to the current gap in stability, accuracy, and other aspects of PCB substrates in China, they cannot meet the performance requirements of Mini LED for PCB substrates. The PCB substrates required for Mini LED need to be imported from countries and regions such as Japan and South Korea, resulting in high costs. Especially in March and April this year, there was a significant increase in the price of imported PCB substrates, "said the person in charge of the packaging manufacturer.

Qiu Yun, Deputy Director of the Organization Technology Planning Department of BOE Display and Sensor Business Group, stated that for example, the 6-layer 2nd order and 8-layer 3rd order PCB substrates required for Mini LED backlighting cannot be supplied in bulk domestically and can only be imported at high prices.

The relevant person in charge of TCL pointed out in an interview with China Electronics News that after years of adaptation, glass substrates are now relatively mature in terms of equipment and technology, and the supply of glass materials is relatively stable with low costs. So using glass instead of PCB as the LED backplane can not only significantly reduce manufacturing costs, but also help stabilize manufacturer confidence.

According to the relevant person in charge of TCL, compared to the PCB based Mini LED currently promoted by the whole machine factory, the driving cost of glass based TFT is lower while maintaining the same display effect

      Glass substrate still awaiting market inspection

Recently, BOE revealed the new progress of Mini LED on its investor interaction platform. BOE stated that the company is optimistic about the prospects of Mini LED products and has laid out 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 stated that TCL Huaxing has been laying out glass based Mini LEDs since 2018, and now the technology is relatively mature. In the future, whether Mini LED backlight products are to be widely used in TV, tablet, laptop and other markets, TCL Huaxing will definitely choose glass substrates.

When panel factories such as BOE and TCL Huaxing established glass substrate Mini LED backlight as the mainstream direction of the future market, packaging giants including Guoxing Optoelectronics, Ruifeng Optoelectronics, Jufei Optoelectronics, and Jingtai Optoelectronics did not give up their efforts in glass substrate technology.

According to Wang Sen, General Manager of Guoxing Optoelectronics Co., Ltd., its glass based Mini LED backlight related products have been shipped in small quantities and will closely follow the mainstream market in the future.

Ruifeng Optoelectronics also stated in the latest disclosed "Investor Relations Activity Record Form" that the company's Mini LED research project includes both glass substrate and PCB substrate technology paths.

However, TrendForce consulting analyst Chen Shuxun pointed out in an interview with China Electronics News that both PCB substrates and glass substrates have their own advantages and disadvantages. Although glass substrates have outstanding advantages, their disadvantages such as susceptibility to breakage are also quite obvious. Let's wait and see which substrate will become the major trend for Mini LED backlighting in the future.