tft lcd glass substrate made in china

(Yicai Global) June 19 -- China National Building Material has built the country"s first production line capable of producing 8.5th-generation TFT-LCD glass substrates, making China one of few nations to master the technology.

The central state-owned firm"s Bengbu Glass Industry Design and Research built the facility after three years of research, Science and Technology Daily reported. The plant aims to obtain certifications that will allow it to manufacture for domestic display makers.

TFT-LCD, or thin-film-transistor liquid-crystal displays, are classified by the size of their glass substrate. Sixth-generation displays are now widely considered out-dated while 8.5th-gen tech is the most advanced. The newer technologies use larger substrates, which are more efficient to make and can be used in larger screens.

Demand for glass substrates in China reached 260 million square meters in 2018, with demand for 8.5th-gen components making up 233 million, according to the China Optics & Optoelectronics Manufacturers Association. But domestic production is only about 40 million square meters and all below 6th-gen. American and Japanese companies mostly dominate the more advanced segment of the market.

China"s first 8.5-generation tft-lcd glass substrate production line was successfully fired in bengbu, anhui province on Monday, entering the debugging stage of the equipment. The production is expected to reach mass production in September.

TFT-LCD glass substrate is the key strategic material of electronic information display industry.The 8.5 generation tft-lcd glass substrate has a size of 2.2m*2.5m and can be cut into 6 55-inch panels.At present, the 8.5 generation tft-lcd glass substrates for large-size LCD TVS in China are completely dependent on the technology and products of foreign companies, and they cannot be independently produced.

The ignition production line is the project result of the national key research and development program of ministry of science and technology "development and industrialization demonstration of core technology of high-generation electronic glass substrate and cover plate", which is led by China building materials bengbu glass industrial design and research institute.

According to the data of liquid crystal branch of China optical optoelectronics industry association, in 2018, the demand of glass substrate in mainland China is about 260 million square meters, among which the demand of 8.5 generation glass substrate is 233 million square meters, while the annual supply of domestic tft-lcd glass substrate is less than 40 million square meters, and all of them are 6 generation lines or below.

The 8.5 generation tft-lcd glass substrate production represents the high level of modern glass industry large-scale manufacturing, and its core technology has been monopolized by a few foreign enterprises for a long time.Supported by the national key research and development program, bengbu glass industry design and research institute of China building materials co., LTD., with years of accumulation and persistent research, has cooperated with several units to overcome the key technology of high-generation electronic glass, which will provide the key raw material guarantee for China"s LCD panel industry after mass production.

It is reported that after the project volume, China will become one of the few countries in the world to master the production technology of high-generation tft-lcd glass substrate.

AGC has now decided to relocate a cutting-edge glass substrate production facility from within the AGC Group. This investment will significantly reduce the need for capital investment while maintaining the group"s total production capacity.

There has been a large increase in production of TFT-LCD panels in China in recent years which has resulted in an abrupt increase in demand for glass substrates. To accommodate demand growth, the AGC Group has established a supply system by setting up a processing facility in Kunshan, Jiangsu Province, and Shenzhen, Guangdong Province, and a furnace in Huizhou,Guangdong Province.

AGC has also decided to build an 11th generation dedicated glass substrate* furnace in order to address the anticipated growth in demand of TFT-LCD panels that will use similar-sized TFT-LCD glass substrates.

SHANGHAI– Corning Incorporated (NYSE: GLW) today hosted a launch ceremony for its new Gen 10.5 liquid crystal display (LCD) glass substrate manufacturing facility co-located with the BOE Technology Group Co. Ltd. (BOE) plant in the Hefei Xinzhan Hi-Tech Industrial Development Zone in the Anhui Province, China.

This new facility will enable Corning to become the first manufacturer of TFT- grade Gen 10.5 substrates in the world. The largest LCD commercially available glass substrates are 2,940 mm by 3,370 mm, providing the most economical cuts for 65-inch and 75-inch TVs. The Gen 10.5 substrates manufactured at the Hefei facility use Corning® EAGLE XG® Slim glass.

Corning began shipping BOE production samples from the plant in late 2017. The market for large-size TVs, defined as TVs 60” and larger, is projected to grow at a compound annual growth rate of more than 20 percent for the next several years. The Hefei facility is Corning’s third LCD glass plant on the Chinese mainland. The company also operates Gen 8.5 LCD glass plants in Beijing and Chongqing.

“The Hefei Gen 10.5 LCD glass facility is the next milestone in the display business, enabling us to make the world’s largest glass substrate to support the growing global demand for large size TVs,” said James P. Clappin, president of Corning Glass Technologies, at the launch ceremony. “As the industry’s innovation and market leader with the most experience in large Gen substrate production, we’re proud to support the development of China’s LCD industry.”

“We’re delighted to bring the world’s best-in-class Gen 10.5 substrate technology to China in support of the continued growth of the LCD industry and in support of BOE, our valued strategic customer,” commented John Zhang, general manager of Corning Display Technologies at the event. “This plant allows us to deliver on our long-term commitment to BOE and participate in the fastest-growing LCD market in the world while maintaining our overall LCD glass supply demand balance.”

In December 2015, with the support of the Hefei municipal government and other local officials, Corning announced its plans to invest in a new LCD glass facility in the Hefei Xinzhan Hi-Tech Industrial Development Zone in the Anhui Province, China.

Corning (www.corning.com) is one of the world"s leading innovators in materials science, with a more than 165-year track record of life-changing inventions. Corning applies its unparalleled expertise in glass science, ceramic science, and optical physics along with its deep manufacturing and engineering capabilities to develop category-defining products that transform industries and enhance people"s lives. Corning succeeds through sustained investment in RD&E, a unique combination of material and process innovation, and deep, trust-based relationships with customers who are global leaders in their industries.

Corning"s capabilities are versatile and synergistic, which allows the company to evolve to meet changing market needs, while also helping our customers capture new opportunities in dynamic industries. Today, Corning"s markets include optical communications, mobile consumer electronics, display technology, automotive, and life sciences vessels. Corning"s industry-leading products include damage-resistant cover glass for mobile devices; precision glass for advanced displays; optical fiber, wireless technologies, and connectivity solutions for state-of-the-art communications networks; trusted products to accelerate drug discovery and delivery; and clean-air technologies for cars and trucks.

SHANGHAI, May 9, 2018- Corning Incorporated (NYSE: GLW) today hosted a launch ceremony for its new Gen 10.5 liquid crystal display (LCD) glass substrate manufacturing facility co-located with the BOE Technology Group Co. Ltd. (BOE) plant in the Hefei Xinzhan Hi-Tech Industrial Development Zone in the Anhui Province, China.

This new facility will enable Corning to become the first manufacturer of TFT- grade Gen 10.5 substrates in the world. The largest LCD commercially available glass substrates are 2,940 mm by 3,370 mm, providing the most economical cuts for 65-inch and 75-inch TVs. The Gen 10.5 substrates manufactured at the Hefei facility use Corning® EAGLE XG® Slim glass.

Corning began shipping BOE production samples from the plant in late 2017. The market for large-size TVs, defined as TVs 60" and larger, is projected to grow at a compound annual growth rate of more than 20 percent for the next several years. The Hefei facility is Corning"s third LCD glass plant on the Chinese mainland. The company also operates Gen 8.5 LCD glass plants in Beijing and Chongqing.

"The Hefei Gen 10.5 LCD glass facility is the next milestone in the display business, enabling us to make the world"s largest glass substrate to support the growing global demand for large size TVs," said James P. Clappin, president of Corning Glass Technologies, at the launch ceremony. "As the industry"s innovation and market leader with the most experience in large Gen substrate production, we"re proud to support the development of China"s LCD industry."

"We"re delighted to bring the world"s best-in-class Gen 10.5 substrate technology to China in support of the continued growth of the LCD industry and in support of BOE, our valued strategic customer," commented John Zhang, general manager of Corning Display Technologies at the event. "This plant allows us to deliver on our long-term commitment to BOE and participate in the fastest-growing LCD market in the world while maintaining our overall LCD glass supply demand balance."

In December 2015, with the support of the Hefei municipal government and other local officials, Corning announced its plans to invest in a new LCD glass facility in the Hefei Xinzhan Hi-Tech Industrial Development Zone in the Anhui Province, China.

About Corning IncorporatedCorning (www.corning.com) is one of the world"s leading innovators in materials science, with a more than 165-year track record of life-changing inventions. Corning applies its unparalleled expertise in glass science, ceramic science, and optical physics along with its deep manufacturing and engineering capabilities to develop category-defining products that transform industries and enhance people"s lives. Corning succeeds through sustained investment in RD&E, a unique combination of material and process innovation, and deep, trust-based relationships with customers who are global leaders in their industries. Corning"s capabilities are versatile and synergistic, which allows the company to evolve to meet changing market needs, while also helping our customers capture new opportunities in dynamic industries. Today, Corning"s markets include optical communications, mobile consumer electronics, display technology, automotive, and life sciences vessels. Corning"s industry-leading products include damage-resistant cover glass for mobile devices; precision glass for advanced displays; optical fiber, wireless technologies, and connectivity solutions for state-of-the-art communications networks; trusted products to accelerate drug discovery and delivery; and clean-air technologies for cars and trucks.

Core reminder: On October 21, the 8.5-generation TFT-LCD glass substrate and cadmium telluride power generation glass independently developed and produced by China National Building Material Triumph Group and China Space Station, C919 domestic large aircraft, "Nine Chapters" quantum computer, "Struggle" Major scientific and technological achievements such as the No. 2 full-sea deep manned submersible, appeared on the same stage at the National "Thirteenth Five-Year" Scientific and Technological Innovation Achievement Exhibition.

On October 21, the 8.5-generation TFT-LCD glass substrate and cadmium telluride power generation glass independently developed and produced by China National Building Materials Triumph Major scientific and technological achievements such as deep manned submersibles, appeared on the same stage at the National "Thirteenth Five-Year" Science and Technology Innovation Achievement Exhibition.

During the "13th Five-Year Plan" period, Trisun Group has produced a number of world-leading major innovations with independent intellectual property rights, including the world’s thinnest 0.12 mm ultra-thin touch glass, China’s first 8.5-generation TFT-LCD glass substrate, 30 micron flexible foldable glass, the world"s first large-area 1.92 square meter cadmium telluride power generation glass, copper indium gallium selenide power generation glass with a photoelectric conversion rate of over 20%, and high-performance hollow glass beads used in the "Hippocampus", etc. A series of innovative achievements have helped China"s glass industry to achieve high-level technological self-reliance.

With the support of the national "Thirteenth Five-Year" key research and development project, Kaisheng Group pioneered the gas-electric hybrid high-efficiency melting, new type of precious metal runner ultra-thin float forming process with independent intellectual property rights, and built China"s first 8.5-generation float glass. TFT-LCD glass substrate production line. The successful development of this project has broken the status quo that the core technology of 8.5-generation TFT-LCD glass substrate production has been blocked by foreign countries for a long time, and has realized the "zero" breakthrough of China"s high-generation glass substrates, which is important for ensuring the security of China"s trillion-level display industry chain supply chain. Significance.

After a new company is established jointly with Shenzhen China Star Optoelectronics Semiconductor Display Technology, a glass substrate processing line will be installed at the plant. Mass-production is planned to start in 2019.

AGC has been enhancing its supply system to meet expanding demand for glass in China by establishing processing bases which support the eighth generation of glass substrates in Kunshan, Jiangsu Province, and Shenzhen, Guangdong Province, as well as a base to manufacture raw glass for TFT-LCDs in Huizhou, Guangdong Province.

The new glass substrate-processing base, supporting the eleventh generation, will be established to meet demand in the Chinese market, which is expected to expand.

AGC Asahi Glass is the parent company of the AGC Group, a glass solution provider and supplier of flat, automotive and display glass, chemicals, ceramics and other high-tech materials and components

Corning Incorporated has hosted a launch ceremony for its new Gen 10.5 liquid crystal display (LCD) glass substrate manufacturing facility co-located with the BOE Technology Group (BOE) plant in the Hefei Xinzhan Hi-Tech Industrial Development Zone in the Anhui Province, China.

This new facility will enable Corning to become the first manufacturer of TFT- grade Gen 10.5 substrates in the world. The largest LCD commercially available glass substrates are 2940 mm by 3370 mm, providing the most economical cuts for 65-inch and 75-inch TVs. The Gen 10.5 substrates manufactured at the Hefei facility use Corning EAGLE XG Slim glass.

Corning began shipping BOE production samples from the plant in late 2017. The market for large-size TVs, defined as TVs 60" and larger, is projected to grow at a compound annual growth rate of more than 20 percent for the next several years. The Hefei facility is Corning"s third LCD glass plant on the Chinese mainland. The company also operates Gen 8.5 LCD glass plants in Beijing and Chongqing.

SHANGHAI, China– Corning Incorporated (NYSE: GLW) has launched its new Gen 10.5 liquid crystal display (LCD) glass substrate manufacturing facility co-located with the BOE Technology Group Co. Ltd. (BOE) plant in the Hefei Xinzhan Hi-Tech Industrial Development Zone in the Anhui Province, China.

This new facility will enable Corning to become the first manufacturer of TFT- grade Gen 10.5 substrates in the world. The largest LCD commercially available glass substrates are 2,940 mm by 3,370 mm, providing the most economical cuts for 65-in and 75-in TVs. The Gen 10.5 substrates manufactured at the Hefei facility use Corning® EAGLE XG® Slim glass.

Corning began shipping BOE production samples from the plant in late 2017. The market for large-size TVs, defined as TVs 60in and larger, is projected to grow at a compound annual growth rate of more than 20 percent for the next several years. The Hefei facility is Corning’s third LCD glass plant on the Chinese mainland. The company also operates Gen 8.5 LCD glass plants in Beijing and Chongqing.

“The Hefei Gen 10.5 LCD glass facility is the next milestone in the display business, enabling us to make the world’s largest glass substrate to support the growing global demand for large size TVs,” said James P. Clappin, president of Corning Glass Technologies, at the launch ceremony. “As the industry’s innovation and market leader with the most experience in large Gen substrate production, we’re proud to support the development of China’s LCD industry.”

“We’re delighted to bring the world’s best-in-class Gen 10.5 substrate technology to China in support of the continued growth of the LCD industry and in support of BOE, our valued strategic customer,” commented John Zhang, general manager of Corning Display Technologies at the event. “This plant allows us to deliver on our long-term commitment to BOE and participate in the fastest-growing LCD market in the world while maintaining our overall LCD glass supply demand balance.”

In December 2015, with the support of the Hefei municipal government and other local officials, Corning announced its plans to invest in a new LCD glass facility in the Hefei Xinzhan Hi-Tech Industrial Development Zone in the Anhui Province, China.

The glass substrate is one of the core layers of TFT LCD. It influences fundamental features of the display in the resolution, light transmittance, thickness, weight, and viewing angle.

The glass substrate is the core component of the TFT LCD and plays a significant role in the upstream of the TFT LCD industry, similar to the silicon wafer in the semiconductor industry.

Since the quality of the glass substrate decides the features of the display in the resolution, light transmittance, thickness, weight, viewing angle, and other important parameters.

The fundamental structure of the TFT LCD is similar to a sandwich, two layers of “bread” (TFT substrate and color filter) sandwiched with “jam” (liquid crystal).

Considering the unique environment in the manufacturing process of TFT-LCD, such as high temperature, high pressure, and environment switching among acidic-neutral-alkaline, the following characteristics of the glass must meet the challenge and quality requirement.

In the manufacturing process, the maximum temperature can reach above 600 ℃, which requires the glass substrate to remain rigid without any sticking even at such a high temperature.

After the etching process, the glass substrate needs to remain with minimal changes, and can’t be left with visible residue and interference with film deposition.

In the process the mother glass is cut into pieces in the required size, with a thickness of only 0.5-0.7mm, the glass needs to have high mechanical strength and elastic modulus >70GPa.

Usually, the size has doubled with each successive generation. From the initial generation 4 (G4) to the current G11, the size of the substrate has grown to 3000*3320mm.

In the global market of glass substrates for TFT-LCD, more than 90% are concentrated in several major manufacturers, such as Corning (America), Asahi Glass (Japan), Nippon Electric Glass (Japan), and AvanStrate (Taiwan).

However, there is still a gap and need for breakthroughs in the glass for high-generation LCD panel production lines and AMOLED alkali-free glass technology. It is hard to achieve high localization in a short time.

Corning Inc, the world"s biggest maker of glass for liquid-crystal displays (LCD), yesterday said it is planning to build a new LCD glass substrate finishing facility in China, marking its first move in tapping the up-and-coming flat panel market there.

Corning said the board has approved the investment, but has not finalized the location, according to a statement released yesterday. The New York-based glassmaker declined to disclose the size of the investment.

With this investment, Corning, which has a 70-percent share in the global LCD glass market, would be the first thin-film-transistor (TFT)-LCD glass substrate supplier to set up a production facility in China.

"Corning is fully committed to the LCD industry in China and to growing with our customers in this important region of the world market," said Nitin Kulkarni, president of Corning Display Technologies in China, in the statement.

Without any plants in China, Corning supplies the three Chinese flat-panel makers -- BOE Technology Group Co (京東方), SVA Group Co (上海廣電) and InfoVision Optoelectronics (龍騰光電) -- with glass from its factories elsewhere.

Last month, Corning launched its second melting facility worth US$1.5 billion in Taiwan, and the company predicted Taiwan would outpace South Korea in consumption of LCD glass by next year.

Overall LCD glass demand will nearly triple next year, fueled mostly by the popularity of LCD televisions, compared with the 46 million square meters consumed in 2004, Corning said.

Last year, flat-panel manufacturers purchased around 74 million square meters, up approximately 60 percent from a year ago, as TFT-LCD screens increasingly replaced bulky cathode-ray-tube computer monitors and demand for LCD TVs grew, the company said.

"TFT-LCD Glass Substrate Market" report presents a comprehensive overview, market shares, and growth opportunities of TFT-LCD Glass Substrate market by product type, application, key manufacturers and key regions and countries. The global TFT-LCD Glass Substrate market size is projected to reach Multimillion USD by 2028, in comparision to 2021, at unexpected CAGR during 2022-2028.

TFT-LCD Glass SubstrateMarket Research Report is spread across 85 Pages with 130 Number of Tables and Figures that provides exclusive data, information, vital statistics, trends, and competitive landscape details in this niche sector.

The Global TFT-LCD Glass Substrate market is anticipated to rise at a considerable rate during the forecast period, between 2022 and 2028. In 2020, the market is growing at a steady rate and with the rising adoption of strategies by key players, the market is expected to rise over the projected horizon.

Due to the COVID-19 pandemic, the global TFT-LCD Glass Substrate market size is estimated to be worth USD million in 2022 and is forecast to a readjusted size of USD million by 2028 with a CAGR of % during the forecast period 2022-2028. Fully considering the economic change by this health crisis, Gen. 5 accounting for % of the TFT-LCD Glass Substrate global market in 2021, is projected to value USD million by 2028, growing at a revised % CAGR from 2022 to 2028. While Television segment is altered to an % CAGR throughout this forecast period.

North America TFT-LCD Glass Substrate market is estimated at USD million in 2021, while Europe is forecast to reach USD million by 2028. The proportion of the North America is % in 2021, while Europe percentage is %, and it is predicted that Europe share will reach % in 2028, trailing a CAGR of % through the analysis period 2022-2028. As for the Asia, the notable markets are Japan and South Korea, CAGR is % and % respectively for the next 6-year period.

The global major manufacturers of TFT-LCD Glass Substrate include Corning, AGC, NEG, Tunghsu Optoelectronic, AvanStrate, IRICO and LG Chem, etc. In terms of revenue, the global 3 largest players have a % market share of TFT-LCD Glass Substrate in 2021.

Report further studies the market development status and future TFT-LCD Glass Substrate Market trend across the world. Also, it splits TFT-LCD Glass Substrate market Segmentation by Type and by Applications to fully and deeply research and reveal market profile and prospects.

Geographically, this report is segmented into several key regions, with sales, revenue, market share and growth Rate of TFT-LCD Glass Substrate in these regions, from 2015 to 2027, covering ● North America (United States, Canada and Mexico)

Some of the key questions answered in this report: ● What is the global (North America, Europe, Asia-Pacific, South America, Middle East and Africa) sales value, production value, consumption value, import and export of TFT-LCD Glass Substrate?

● Who are the global key manufacturers of the TFT-LCD Glass Substrate Industry? How is their operating situation (capacity, production, sales, price, cost, gross, and revenue)?

● What are the upstream raw materials and manufacturing equipment of TFT-LCD Glass Substrate along with the manufacturing process of TFT-LCD Glass Substrate?

● What are the key drivers, restraints, opportunities, and challenges of the TFT-LCD Glass Substrate market, and how they are expected to impact the market?

(NYSE: GLW) today (EST March 27) hosted a grand opening ceremony for the company’s new liquid crystal display (LCD) glass substrate manufacturing facility in the People’s Republic of China.

The plant, located in the Beijing Economic Technological Development Area, is the company’s first TFT-LCD glass production facility on the China mainland. The opening continues Corning’s trend of entering an LCD-producing region as local market demand expands. Corning currently has LCD glass facilities in the U.S., Japan, Korea and Taiwan.

“As an industry leader in TFT-LCD glass and other advanced display products, Corning is committed to providing customers with reliable supply across our global network,” said Bayne. “This facility demonstrates our commitment to China and the growing TFT industry. We have added and will continue to add many people to our organization, including highly skilled technicians and engineers, as we continue to ramp operations over the coming months.”

Previously, Corning stated that it expects global demand for liquid crystal display glass to grow 25% to 30% in 2008, representing an increase of more than 450 million square feet of glass to about 2.2 billion square feet by year-end. While much of that growth is driven by the demand for LCD televisions, smaller applications like LCD monitors, notebooks, and portable devices are also strong factors in overall glass demand.

Corning Incorporated ( http://www.corning.com ) is the world leader in specialty glass and ceramics. Drawing on more than 150 years of materials science and process engineering knowledge, Corning creates and makes keystone components that enable high-technology systems for consumer electronics, mobile emissions control, telecommunications and life sciences. Our products include glass substrates for LCD televisions, computer monitors and laptops; ceramic substrates and filters for mobile emission control systems; optical fiber, cable, hardware & equipment for telecommunications networks; optical biosensors for drug discovery; and other advanced optics and specialty glass solutions for a number of industries including semiconductor, aerospace, defense, astronomy and metrology.

Best known for its Gorilla Glass and related families of products - extra-hard glass used as the upper surface on touchscreens to protect against scratches and chipping - Corning supplies glass to the majority of the liquid-crystal display (LCD) industry. Its latest plant, located in the Hefei Xinzhan Hi-Tech Industrial Development Zone of the Anhui Province, China, is an indication of just how big both the company and the products it creates have become: The factory has been opened to build the largest LCD substrates in the world, suitable for building 75" displays more economically than the smaller competition.

"The Hefei Gen 10.5 LCD glass facility is the next milestone in the display business, enabling us to make the world"s largest glass substrate to support the growing global demand for large size TVs," claimed James P. Clappin, president of Corning Glass Technologies, during the launch ceremony. "As the industry"s innovation and market leader with the most experience in large Gen substrate production, we"re proud to support the development of China"s LCD industry."

The generation numbers for glass substrates refer to panel size, rather than any underlying technology: The next largest size manufactured by Corning, Gen 8.5, measures 2,200 × 2,500mm; the new Gen 10.5 substrate sheets, by contrast, measure 2,940 × 3,370mm, making it perfect, the company claims, for 60" and larger TV production - and is the first Gen 10.5 substrate suitable for use in thin-film transistor (TFT) displays.

The Hefei facility was announced back in December 2015, and began shipping its first sample-production substrates in late 2017. This week"s opening marks its shift into full-scale production. The factory"s current output is earmarked for Chinese display maker BOE Technology Group, with which Corning has signed a long-term supply agreement.

Influence of the slight adjustment of oxides on the structural and physico-chemical properties of thin film transistor-liquid crystal display substrate glass

Data from: Influence of the slight adjustment of oxides on the structural and physico-chemical properties of thin film transistor-liquid crystal display substrate glass

By the slight adjustment of oxides constituting thin film transistor-liquid crystal display (TFT-LCD) substrate glass, including equal mole fraction substitution of Al2O3, GeO2, B2O3, P2O5 and ZrO2 for SiO2, as well as the substitution of CaO for SrO with the total contents unchanged, the structural and physico-chemical properties of the glass was investigated by Raman spectroscopy and other measurements. The results showed that the short-range disorder brought by the substitution of GeO2, B2O3 and P2O5 for SiO2 could weaken the stability and compactness of the glass network, and the physico-chemical properties deteriorated, while the process of glass melting would become easier accordingly. The short-range disorder by the substitution of ZrO2 for SiO2 with 1% mole fraction showed a little difference with other samples. Finally, the substitution of modified cations, such as CaO and SrO, showed a smaller variation compared with the substitution of network formers. On the condition of 1% mole fraction substitution of oxides investigated, the variation of samples showed a reasonable change and the performance was basically all satisfied for the use of TFT-LCD substrate.

Thin film transistor-liquid crystal display (TFT-LCD) substrate glass is a kind of substrate for electronic display [1,2]. In order to meet the demand of the process of LCD devices, the glass needs to be alkali-free. The international representative products such as Corning Eagle XG™ and Asahi AN100™ mainly contain some conventional oxides, such as SiO2, Al2O3, B2O3, MgO, CaO and SrO [3,4]. The influence of some unconventional oxides on the structural and physico-chemical properties of alkali-free glass deserve further study for the improvement of the glass industry. For example, some glass network formers, such as GeO2 and P2O5, and the modified cations ZrO2, the substitution of them for SiO2 could play an important role in shaping the glass network and improving the performance of glass. Herein, we studied the influence of the slight adjustment of oxides mentioned above. To investigate the structural and physico-chemical properties of the glass, Raman spectroscopy, as well as some physico-chemical measurements were used to evaluate the effects of the slight adjustment of oxides.

Seven kinds of the chemical compositions of alkali-free glass for TFT-LCD substrate are summarized in table 1, wherein sample 1 is the reference sample for the other six samples, which are acquired by the slight adjustment of oxides from sample 1. The details are as follows: sample 2 is acquired by 1% mole fraction substitution of Al2O3 for SiO2 with equal total amount compared with sample 1, and the other samples are acquired in the same way as sample 2, including 1% mole fraction substitution of GeO2 for SiO2 for sample 3, 1% mole fraction substitution of B2O3 for SiO2 for sample 4, 1% mole fraction substitution of P2O5 for SiO2 for sample 5, 1% mole fraction substitution of SrO and CaO for sample 6 and 1% mole fraction substitution of ZrO2 for SiO2 for sample 7. By the slight adjustment of the oxides, the structural along with the physico-chemical properties were investigated.

According to the chemical compositions shown in table 1, the weighted and evenly mixed glass batch was heated in a platinum crucible in a Silicon Molybdenum Furnace with the following melting and annealing procedure: (i) heating from room temperature up to 1000°C with a heating rate of 4°C min−1; (ii) heating from 1000°C up to 1640°C with a heating rate of 2°C min−1; (iii) dwelling in 1640°C for 2 h for fining of glass liquid; (iv) pouring the glass liquid onto a copper plate for glass formation; and (v) annealing at 650°C for 1 h in a muffle furnace and then cooling down to room temperature. The prepared glass samples were cut and ground for the following measurements.

The effects of the slight adjustment of oxides on the structure of the glass was studied by Raman spectroscopy. According to the theory of irregular network of glass, the average non-bridging oxygens Onb in oxygen polyhedron is expressed by X, the average bridging oxygens Ob is expressed by Y, and Z represents the average coordination number of network formers [5–7]. As a result of RO/Al2O3 > 1, Al2O3 will be treated as network former. So the network formers are as follows: SiO2, GeO2, Al2O3, B2O3 and P2O5, while MgO, CaO, SrO and ZrO2 are treated as modified cations. Al3+ shows the priority to be coordinated by oxygen ions to form an [AlO4] tetrahedron compared with B3+ [8]. As shown in table 1, RO/Al2O3 > 1 and (RO-Al2O3)/B2O3 < 1, so Al3+ will mainly exist in the form of an [AlO4] tetrahedron, and B3+ will enter the network with more [BO3] triangle and less [BO4] tetrahedron. Table 2 shows the average coordination number Z of seven samples, wherein R represents the ratio of oxygen ions and network former ions, X = 2R − Z and Y = 2Z − 2R [5–7].

As a result of the similar components for all samples, the architecture of the glass network basically did not show too many differences, which are mainly dominated by the closer network formers such as SiO2, B2O3 and Al2O3, as well as the same total amount of modified cations of CaO, MgO and SrO. As shown in figure 1, Raman peaks for all seven samples were mainly located at three frequencies with the closer intensity, indicating that the entity and compactness of the glass network changed a little with the substitution of oxides for SiO2, proved by the closer Y and X values shown in table 2. The highest peak intensity was distributed in low frequency at around 480 cm−1 assigning to the bending vibration of Si–Ob in Si–Ob–Si bonds [9]. The second highest peak intensity was in the region of 850–1250 cm−1 relating to the stretching vibration of bridging oxygens Si–Ob and the stretching vibration of non-bridging oxygens Si–Onb [10,11]. The third highest peak intensity was in the middle frequency at around 803 cm−1 relating to the symmetric stretching vibration of Si–Ob–Si between [SiO4] tetrahedrons [9,12]. Some weaker intensity peaks distributed at around 710 cm−1, 1310 cm−1 and 1440 cm−1 could attribute to the vibration of the B–O bond, wherein a peak at 710 cm−1 is assigned to B–O–B bending vibration in the [BO3] triangle [13], and peaks located at around 1310 cm−1 and around 1440 cm−1 are assigned to B–Ob stretching vibration and B–Onb stretching vibration in the [BO3] triangle, respectively [14].

For samples 1–7, there were three main fit peaks in this region. The first peak with the highest intensity was at a frequency of around 1030 cm−1, corresponding to stretching vibration of bridging oxygens Si–Ob. Some researchers assumed that this peak should be owing to the vibration of bridging oxygens except Q4 unit [16,17]. As Q1 and Q2 units were not obviously found in this study, the peak located at around 1030 cm−1 should be derived from the Q3 unit. The second highest peak intensity located at around 1170 cm−1 corresponded to stretching vibration of bridging oxygens Si–Ob in the Q4 unit [16,17]. The weakest peak was located at around 1110 cm−1, corresponding to stretching vibration of non-bridging oxygens Si–Onb in the Q3 unit. As shown in figure 2a, peaks at around 1030 cm−1 and 1170 cm−1 accounted for most of the region, indicating that the vibration of bridging oxygens Si–Ob dominates in alkali-free glasses, in accordance with the higher Y value roughly estimated in table 2.

Secondly, compared with reference sample 1, samples 2 and 4 show a higher ratio of Al/Si. With the replacement of Si4+ by Al3+, some non-bridging oxygens will coordinate Al3+ to form an [AlO4] tetrahedron to connect with the [SiO4] tetrahedron in the glass network, and these non-bridging oxygens are the very ones from the Q3 structure unit. So with the increase of Al/Si, the Q3 unit decreased and the Q4 unit increased. In the same way, for samples 3 and 5, some Si4+ were replaced by Ge4+ or P5+, accordingly. The Q3 unit decreased with the decrease of SiO2 and can be connected with the [GeO4] or [PO4] tetrahedron to form the Q4 unit. So the strengthening of Q4 vibration probably came from Si–Ob–Al caused by the formation of an [AlO4] tetrahedron for samples 2 and 4, and Si–Ob–Ge, Si–Ob–P for samples 3 and 5. This is why the Si–Onb vibration at around 1110 cm−1 weakened, while the Si–Ob vibration at 1170 cm−1 strengthened for samples 2, 3, 4 and 5. Basically, with the higher ratio of Al/Si, Si–Ob–Si and Si–Ob–B decreased, while Si–Ob–Al increased, along with the newcomer Si–Ob–Ge or Si–Ob–P, bringing more distortion into the glass network compared with sample 1, causing the increase of the disorder degree of the network and lower frequency shift of the peaks.

It can be derived and inferred from above, the low frequency bending vibration of Si–Ob in Si–Ob–Si bonds dominated in alkali-free glass, and B3+ was mainly found in the form of a [BO3] triangle owing to its inferiority to Al3+ coordinated by oxygen ions and fewer alkali-earth ions. As for the [SiO4] tetrahedron, Q3 and Q4 units accounted for the most in four kinds of [SiO4] units. With the substitution of oxides for SiO2, Q3 decreased and Q4 increased, but the disorder degree of the network increased, embodied in the lower frequency shift of the Raman peak. Sample 7 with Zr4+ showed more peak shift than others, mainly owing to the high electric field of Zr4+ that can significantly affect the network of glass.

The thermal expansion softening temperature were between 767°C and 791°C for seven samples. They also showed a good agreement with the tightness of the glass network as discussed above.

Table 5 lists the optical properties of the seven samples, including the average transmittance in visible light and the refractive index. All seven samples were cut and ground to the same thickness of 2 mm. As shown in table 5, the average transmittance of seven samples were very close to each other with the values of 90–91%, as well as the refractive index at around 1.520–1.526, showing very small differences with each other. From the analysis of the Raman spectra above, the glass network of all samples with the slight adjustment of oxides did not show too much difference. So the optical properties which were mainly dominated by the network and compositions exhibited similar performances accordingly.

Meanwhile, sample 7 showed a little smaller transmittance and a little larger refractive index than other samples. The extranuclear electrons of Zr4+ were easily polarized owing to the larger radius of Zr4+, and the refractive index of glass relates to the polarity of electrons. The increasing refractive index also affects the transmittance [22]. As a result of small amount of substitution of ZrO2 for SiO2 for sample 7, the effect of Zr4+ was not too significant.

Table 6 shows the logarithm volume resistivity of samples measured at 25°C and 250°C, respectively. TFT-LCD substrate glass is a kind of alkali-free glass and the alkali-earth ions are the primary conductive elements, which show a lower conductivity than alkaline ions. This is why the volume resistivity of TFT-LCD substrate glass is larger than conventional soda lime glass. At a temperature of 25°C, the logarithm volume resistivities of the TFT-LCD substrate glass is between 15.1 Ω cm and 15.9 Ω cm. When the samples were heated, the energy of alkali-earth ions increased, and the number of ions with high enough energy in the glass network that could migrate in the electric field also increased, causing the decrease of the resistivity to around 13 Ω cm at 250°C shown in table 5, which declined about 100 times compared with that at 25°C.

The curves of high temperature resistivity for the seven samples are shown in figure 4. The resistivities decreased with the temperature ranging from 1300°C to 1600°C. When the temperature was not high enough to destroy the network of glass, for example, at 1300–1400°C, alkali-earth ions will move in the gap of the network to conduct.

As for the comparison of samples 3 and 1, the resistivity became lower by the substitution of GeO2 for SiO2. Because the volume of [GeO4] is larger than the [SiO4] tetrahedron, the network of glass expands to generate a more relaxed structure, which benefited from the movement for alkali-earth ions and reduced the resistivity for sample 3.

Finally, with the increase of temperature, the glass network vanished for all seven samples, and the mechanism of conduction was the free movement of alkali-earth ions in molten glass liquid, leading to the same value in the final molten state for about 50 Ω·cm for all seven samples whose number of alkali-earth ions were equal.

Figure 5 shows the curves of high temperature viscosity of the seven samples in the range of 1100–1700°C, wherein data ranging from 1200°C to 1550°C were the measured values, corresponding to viscosity of 101.5–103.2 Pa s, and data beyond that were fitted by the Fulcher equation [23,24]. As a matter of fact, the difference between measured data and fitted data was less than 1°C. So in figure 5, only the smooth curves of fitted data were shown. Table 7 shows some reference points of viscosity-temperature characteristics for float glass, including melting point of glass (Tm), forming point of glass (Tf), working point of glass (Tw) and the range for polishing area and slow cooling area.

Secondly, GeO2 is easier to become molten than SiO2, and the substitution of GeO2 for SiO2 will bring the short-range disorder as a result of the different volumes of [GeO4] and [SiO4] tetrahedrons in the glass network, making the network loose and the reference points of viscosity-temperature characteristics decrease. By comparison of sample 3 and sample 1, melting point decreased for 8°C and working point decreased for 14°C with the substitution of 1% mole fraction.

Sample 4 was acquired by the substitution of B2O3 for SiO2 with 1% mole fraction. As a result of (RO-Al2O3)/B2O3 < 1, with the increase of B2O3 and decrease of SiO2, the [SiO4] tetrahedron decreased and the [BO3] triangle increased, increasing the disorder and lowering the compactness of the network, and thus making the viscosity of glass liquid reduced. By comparison of sample 4 and sample 1, with the increase of B2O3 and decrease of SiO2 for 1% mole fraction, melting point and working point decreased for 11°C and 9°C, respectively.

For sample 5 and sample 1 with the substitution of P2O5 for SiO2, the reference points of viscosity-temperature characteristics decreased more than the other samples. P2O5 can lower the melting point probably owing to its small viscous activation energy, meanwhile, P5+ can form a [PO4] tetrahedron and enter the network with the P=O double bond, which is an asymmetry centre and will make the structure relaxed and thus lower the viscosity of the glass liquid. By comparison of sample 5 and sample 1, melting point and working point decreased for 18°C and 25°C, respectively, exhibiting the most decrease for all samples.

By the slight adjustment of oxides of the TFT-LCD substrate glass, including equal mole fraction substitution of Al2O3, GeO2, B2O3, P2O5 and ZrO2 for SiO2, as well as the substitution of CaO for SrO with the total contents unchanged, the structure and physico-chemical properties of glass was investigated. The results were as follows.(i) The architecture of the glass network did not show too much difference with the substitution of 1% mole fraction for network formers and modified cations. The low frequency bending vibration of Si–Ob in Si–Ob–Si bonds dominated in alkali-free glass, and B3+ was mainly found in the form of a [BO3] triangle owing to its inferiority to Al3+ coordinated by oxygen ions and fewer alkali-earth ions. As for the [SiO4] tetrahedron, Q3 and Q4 units accounted for the most in four kinds of [SiO4] units. With the substitution of oxides for SiO2, Q3 decreased and Q4 increased, but the disorder degree of network increased, embodied in the lower frequency shift of the Raman peak. Sample 7 with Zr4+ showed more peak shift than others, mainly owing to the high electric of Zr4+ that can significantly affect the glass network.

(ii) The stability and entirety of the glass network deteriorated by substitution of GeO2, B2O3, P2O5 for SiO2, and some physiochemical property indexes got worse, such as the decrease of elastic modulus and shear modulus for the mechanical properties, the increase of the thermal expansion coefficient for the thermal properties, and the decrease of the reference points of viscosity-temperature characteristics. Accordingly, the process for float glass became easier by the substitution, which presented a contrary tendency. For example, the melting point of the glass and the resistivity of glass liquid both decreased, which would contribute to the melting process of glass.

(iii) For the substitution of Al2O3 and ZrO2 for SiO2, the stability of the network did not show significant deterioration, probably owing to the [AlO4] tetrahedron and the [ZrO6] octahedron. They can enter the network to connect with the [SiO4] tetrahedron and the compactness could be strengthened and the property indexes correspondingly became better, such as the increase of elastic modulus and shear modulus for the mechanical properties, the decrease of the thermal expansion coefficient for the thermal properties, and the increase of the viscosity-temperature characteristics. Meanwhile, the process for float glass became harder by the substitution. For example, the melting point of glass and the resistivity of glass liquid both increased, bringing more difficulties to the melting process. As for the 1% mole fraction substitution of oxides investigated above, all the values exhibited variations in a reasonable range.

Analysis on the development trend of liquid crystal substrate glass[C]. Electronic-Glass Technology Papers of Electronic Glass Branch Committee, Chinese Ceramic Society. Beijing, China: Electronic-Glass Technology, Chapter, 10–15.

Raman spectroscopic investigation of the structure of silicate glasses. III. Raman intensities and structural units in sodium silicate glasses. J. Chem. Phys.

Raman spectroscopic investigation of the structure of silicate glasses (II). Soda-alkaline earth-alumina ternary and quaternary glasses. J. Non Cryst. Solids

Data from: Influence of the slight adjustment of oxides on the structural and physico-chemical properties of thin film transistor-liquid crystal display substrate glass