阅读说明：本技术 一种tft基板玻璃退火工艺及采用其制备的tft基板玻璃 (TFT substrate glass annealing process and TFT substrate glass prepared by adopting same ) 是由 田英良 李淼 赵志永 王答成 王为 徐剑 于 2020-12-28 设计创作，主要内容包括：本发明属于TFT基板玻璃加工技术领域,具体公开了一种基于冷却定形速率的TFT基板玻璃退火工艺,对现有的保温阶段、慢冷阶段和快冷阶段三个阶段的加工参数形成了理论依据,为退火加工工艺提供数据支持,为本行业提供了极大的方便。采用本发明的退火工艺后,溢流法生产TFT基板玻璃退火质量得到极大的改善,再热收缩率及最大应力值都降低75％以上,OLED显示用TFT基板玻璃再热收缩率为5-8ppm,LCD显示用TFT基板玻璃再热收缩率为24-45ppm,TFT基板玻璃的板面最大应力为30-60PSI。(The invention belongs to the technical field of TFT (thin film transistor) substrate glass processing, and particularly discloses a TFT substrate glass annealing process based on a cooling and setting rate, which forms a theoretical basis for processing parameters of three stages of a heat preservation stage, a slow cooling stage and a fast cooling stage in the prior art, provides data support for an annealing processing technology, and provides great convenience for the industry. After the annealing process is adopted, the annealing quality of TFT substrate glass produced by an overflow method is greatly improved, the reheating shrinkage rate and the maximum stress value are both reduced by over 75 percent, the reheating shrinkage rate of the TFT substrate glass for OLED display is 5-8ppm, the reheating shrinkage rate of the TFT substrate glass for LCD display is 24-45ppm, and the maximum stress of the plate surface of the TFT substrate glass is 30-60 PSI.)

1. A TFT substrate glass annealing process based on cooling and setting rates is characterized in that the substrate glass annealing process comprises a heat preservation stage, a slow cooling stage and a fast cooling stage, and the cooling and setting length of a melt is 200-400 mm;

at the heat preservation stage, the annealing heat preservation time isThe length of the heat preservation section of the annealing furnace is

k1 and k2 are scaling factors,for the cooling setting rate,. DELTA.T is the glass melt viscosity 10⁴Temperature T corresponding to poise₄To a glass melt viscosity of 10^11.5Temperature T corresponding to poise_11.5Δ T is the initial forming feed temperature T₄To the forming termination temperature T_11.5The corresponding time range;

in the slow cooling stage, the substrate glass is at a viscosity of 10^14.5Poise corresponding temperature T_14.5To viscosity of 10⁴²Poise corresponding temperature T₄₂In the range of slow cooling rate V_m＝(2.5×10^-6α^-1)/d^5/9(ii) a The length of the slow cooling section of the annealing furnace is calculated by the following formula:

T_mtemperature range of slow cooling stage, V₀The running speed of the annealing furnace slow cooling section glass plate is set;

in the rapid cooling stage, the substrate glass is at viscosity 10⁴²Poise corresponding temperature T₄₂To 160 ℃ and a rapid cooling rate V_k＝(10×10^-6α^-1)/d^5/9；

The length of the quick cooling section of the annealing furnace is calculated by the following formula:

T_ktemperature range of the rapid cooling stage, V₁The running speed of the glass plate at the fast cooling section of the annealing furnace is set;

wherein alpha is a linear thermal expansion coefficient of 30-380 ℃; d is the maximum thickness of the glass base plate.

2. The TFT substrate glass annealing process based on cooling setting rate according to claim 1,the temperature is 40-70 ℃/s, the annealing heat preservation time is 8-14 s, and the length of the heat preservation section of the annealing furnace is 800-1400 mm.

3. The TFT substrate glass annealing process based on the cooling setting rate as claimed in claim 1, wherein the length of the slow cooling section of the annealing furnace is 707-2216 mm.

4. The TFT substrate glass annealing process based on the cooling setting rate of claim 1, wherein the length of the fast cooling section of the annealing furnace is 144-415 mm.

5. The TFT substrate glass annealing process based on the cooling setting rate of claim 1, wherein the total length of the annealing furnace is 1692-4031 mm.

6. The TFT substrate glass prepared by the TFT substrate glass annealing process based on the cooling and setting rate as claimed in any one of claims 1 to 5, wherein the TFT substrate glass comprises TFT substrate glass for OLED display and TFT substrate glass for LCD display, the reheating shrinkage rate of the TFT substrate glass for OLED display is 5-8ppm, the reheating shrinkage rate of the TFT substrate glass for LCD display is 24-45ppm, and the maximum plate surface stress of the TFT substrate glass is 30-60 PSI.

Technical Field

The invention belongs to the technical field of TFT (thin film transistor) substrate glass processing, and particularly discloses a TFT substrate glass annealing process and TFT substrate glass prepared by adopting the same.

Background

The substrate glass is produced by rapidly cooling and shaping a glass melt, a mass point deviates from an equilibrium position in the cooling and shaping process and generates larger thermal stress, but an annealing furnace is relatively short, the substrate glass cannot be fully annealed, the thermal shrinkage is often as high as dozens of ppm (the ratio of the shrinkage to the original length), even hundreds of ppm, and the requirement that the reheating shrinkage rate of the substrate glass is less than 10ppm for high-resolution LCD and OLED display products cannot be realized.

The overflow method is an important process for producing TFT substrate glass, seventy-five percent of high-end substrate glass is realized by adopting the process, the process belongs to a vertical production process and is limited by the height of a production workshop, an annealing furnace cannot have a length of 70-100 m like a float process, so that the annealing process of the overflow method annealing furnace has to be accurate and efficient to realize high-quality annealing of the substrate glass in a relatively short annealing furnace, the glass can quickly realize structural densification, the reheating shrinkage rate of the substrate glass is reduced, the reheating shrinkage rate is one of parameters which need to be mainly studied when the substrate glass is used for preparing a TFT, the reheating shrinkage rate influences the alignment precision and quality of pixel points, the reheating shrinkage rate of the TFT substrate glass generally used for OLED display is required to be less than 10ppm, the reheating shrinkage rate of the TFT substrate glass used for LCD display is required to be less than 30ppm, but the heat shrinkage rate of the substrate glass which is not subjected to precise annealing treatment is, sometimes, in order to make up for the insufficient reheat shrinkage index of the substrate glass, the substrate glass is subjected to a re-annealing treatment in a horizontal annealing furnace, which not only increases the production process and cost, but also causes risks of appearance scratches and surface particulate matter increase. In addition, thermal stress in the substrate glass can also cause birefringence, which affects color shift and image distortion of the LCD or OLED, requiring stress control at 100PSI (1 PSI ═ 6.895 kPa). Therefore, it is a very urgent technical problem to solve the high-efficiency annealing of the substrate glass by the overflow method.

Disclosure of Invention

The invention aims to provide a TFT substrate glass annealing process and TFT substrate glass prepared by adopting the same, and solves the problem that the prior art cannot realize smaller reheating shrinkage rate of the TFT substrate glass.

The invention is realized by the following technical scheme:

a TFT substrate glass annealing process based on cooling and setting speed comprises a heat preservation stage, a slow cooling stage and a fast cooling stage, wherein the cooling and setting length of a melt is 200-400 mm;

at the heat preservation stage, the annealing heat preservation time isThe length of the heat preservation section of the annealing furnace is

k1 and k2 are scaling factors,for the cooling setting rate,. DELTA.T is the glass melt viscosity 10⁴Temperature T corresponding to poise₄To a glass melt viscosity of 10^11.5Temperature T corresponding to poise_11.5Δ T is the initial forming feed temperature T₄To the forming termination temperature T_11.5The corresponding time range;

in the slow cooling stage, the substrate glass is at a viscosity of 10^14.5Poise corresponding temperature T_14.5To viscosity of 10⁴²Poise corresponding temperature T₄₂In the range of slow cooling rate V_m＝(2.5×10^-6α^-1)/d^5/9(ii) a The length of the slow cooling section of the annealing furnace is calculated by the following formula:

T_mtemperature range of slow cooling stage, V₀The running speed of the annealing furnace slow cooling section glass plate is set;

in the rapid cooling stage, the substrate glass is at viscosity 10⁴²Poise corresponding temperature T₄₂To 160 ℃ and a rapid cooling rate V_k＝(10×10^-6α^-1)/d^5/9；

The length of the quick cooling section of the annealing furnace is calculated by the following formula:

T_ktemperature range of the rapid cooling stage, V₁The running speed of the glass plate at the fast cooling section of the annealing furnace is set;

wherein alpha is a linear thermal expansion coefficient of 30-380 ℃; d is the maximum thickness of the glass base plate.

Further, in the present invention,the temperature is 40-70 ℃/s, the annealing heat preservation time is 8-14 s, and the length of the heat preservation section of the annealing furnace is 800-1400 mm.

Furthermore, the length of the slow cooling section of the annealing furnace is 707-2216 mm.

Further, the length of the fast cooling section of the annealing furnace is 144-415 mm.

Further, the total length of the annealing furnace is 1692-4031 mm.

The invention also discloses TFT substrate glass prepared by the TFT substrate glass annealing process based on the cooling setting rate, wherein the TFT substrate glass comprises TFT substrate glass for OLED display and TFT substrate glass for LCD display, the reheating shrinkage rate of the TFT substrate glass for OLED display is 5-8ppm, the reheating shrinkage rate of the TFT substrate glass for LCD display is 24-45ppm, and the maximum plate surface stress of the TFT substrate glass is 30-60 PSI.

Compared with the prior art, the invention has the following beneficial technical effects:

the invention discloses a TFT substrate glass annealing process based on a cooling and setting rate, which forms a theoretical basis for the processing parameters of the existing three stages of a heat preservation stage, a slow cooling stage and a fast cooling stage, provides data support for an annealing processing process and provides great convenience for the industry. The TFT substrate glass produced by the overflow method before the patent of the invention is not implemented has relatively poor annealing quality, the reheating shrinkage rate of the TFT substrate glass for OLED display is 20-43ppm, the reheating shrinkage rate of the TFT substrate glass for LCD display is 80-150ppm, and the maximum plate surface stress of the TFT substrate glass is 80-200 PSI. After the annealing process is adopted, the annealing quality of TFT substrate glass produced by an overflow method is greatly improved, the reheating shrinkage rate and the maximum stress value are both reduced by over 75 percent, the reheating shrinkage rate of the TFT substrate glass for OLED display is 5-8ppm, the reheating shrinkage rate of the TFT substrate glass for LCD display is 24-45ppm, and the maximum stress of the plate surface of the TFT substrate glass is 30-60 PSI.

Detailed Description

The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.

The annealing parameters designed by the invention aim to eliminate the tensile force of the inner mass point deviating from the equilibrium position caused by the rapid cooling and shaping of the glass melt, and the annealing temperature range, namely the annealing point temperature T₁₃(glass viscosity 10)^13.0Temperature corresponding to poise) and strain point temperature T_14.5(glass viscosity 10)^14.5Temperature corresponding to poise) the particles inside the glass achieve a slow recovery process.

Through research, the cooling and setting rate of the glass melt is foundThe larger the distance of the glass mass point from the equilibrium position, the greater the tensile stress, the longer the annealing time and the longer the annealing furnace.

The invention discloses a TFT substrate glass annealing process based on a cooling and setting rate, which comprises a heat preservation stage, a slow cooling stage and a fast cooling stage;

at the heat preservation stage, the annealing heat preservation time isThe length of the heat preservation section of the annealing furnace is

k1 and k2 are scaling factors,for the cooling setting rate,. DELTA.T is the glass melt viscosity 10⁴Temperature T corresponding to poise₄To a glass melt viscosity of 10^11.5Temperature T corresponding to poise_11.5Δ T is the initial forming feed temperature T₄To the forming termination temperature T_11.5The corresponding time range;

in the slow cooling stage, the substrate glass is at a viscosity of 10^14.5Poise corresponding temperature T_14.5To viscosity of 10⁴²Poise corresponding temperature T₄₂In the range of slow cooling rate V_m＝(2.5×10^-6α^-1)/d^5/9In units of ℃/s; the length of the slow cooling section of the annealing furnace is calculated by the formula (1):

T_mthe temperature range of the slow cooling stage is shown in unit of ℃; v₀The running speed of the glass plate at the slow cooling section of the annealing furnace is in mm/s;

in the rapid cooling stage, the substrate glass is at viscosity 10⁴²Poise corresponding temperature T₄₂To 160 ℃ and a rapid cooling rate V_k＝(10×10^-6α^-1)/d^5/9In units of ℃/s;

the length of the fast cooling section of the annealing furnace is calculated by the formula (2):

T_kthe temperature range of the rapid cooling stage is shown in unit of ℃; v₁The running speed of the glass plate at the fast cooling section of the annealing furnace is in mm/s;

wherein alpha is a linear thermal expansion coefficient of 30-380 ℃ and the unit is 10^-6/° c; d is the maximum thickness of the glass base plate, and the unit is mm.

Optimal melt cooling speed for preparing substrate glass with thickness of 0.4mm-0.7mm based on overflow method40 to 70 ℃/s whenThe annealing time of the formed substrate glass is 8s and the length of the annealing furnace is 800mm at 40 ℃/s; when in useAt 50 ℃/s, the formed substrate glass needs annealing and heat preservation time of 10s, and the heat preservation length of the annealing furnace is 1000 mm; when in useThe annealing temperature-keeping time of the formed substrate glass is 12s at 60 ℃/s, and the length of the heat-keeping section of the annealing furnace is 1200 mm; when in useThe temperature of the formed substrate glass is 70 ℃/s, the annealing holding time is 14s, and the length of the annealing furnace holding section is 1400 mm.

The length of the slow cooling section of the annealing furnace obtained by the formula (1) is determined by the temperature range of the slow cooling section, the slow cooling rate and the running speed of the glass plate of the slow cooling section of the annealing furnace, the running speed is preferably 60 mm/s-150 mm/s, the optimal running speed is 150mm/s, and the length optimization design range of the slow cooling section of the annealing furnace is 707 mm-2216 mm.

The length of the fast cooling section of the annealing furnace obtained by the formula (2) is determined by the temperature range of the fast cooling section, the fast cooling rate and the running speed of the glass plate of the fast cooling section of the annealing furnace, the running speed is preferably 60 mm/s-150 mm/s, the optimal running speed is 150mm/s, and the length of the fast cooling section of the annealing furnace is designed to be 144 mm-415 mm.

In conclusion, the length of the annealing furnace comprises the equipment length of a heat preservation stage, a slow cooling stage and a fast cooling stage, and the total length of the annealing furnace is designed to be 1692-4031 mm.

Specific examples are given below, and as shown in table 1, examples 1 to 4 are directed to OLED display TFT substrate glass; as shown in table 2, examples 5 to 8 are directed to LCD display TFT substrate glass.

TABLE 1

Example 1

After OLED display TFT substrate glass with the thickness of 0.4mm is formed by an overflow method, the annealing process is used for annealing, and the specific process is as follows:

in the stage of heat preservation,the temperature is 40 ℃/s, the length of the heat-preservation section of the annealing furnace is 800mm, and the formed substrate glass needs annealing time of 8 s;

in the slow cooling phase, the temperature range T_mAt 400 ℃ and a slow cooling rate V_m49.43 ℃/s and the running speed V of the glass plate at the slow cooling section of the annealing furnace₀100mm/s, the length L of the slow cooling section of the annealing furnace_mIs 809 mm;

in the fast cooling phase, the temperature range T_kAt 300 ℃ and a rapid cooling rate V_k197.73 ℃/s and the running speed V of the glass plate at the fast cooling section of the annealing furnace₁Is 100mm/s, and the length L of the fast cooling section of the annealing furnace_kIs 152 mm.

Example 2

After OLED display TFT substrate glass with the thickness of 0.5mm is formed by an overflow method, the annealing process is used for annealing, and the specific process is as follows:

in the stage of heat preservation,the temperature is 50 ℃/s, the length of the heat-preservation section of the annealing furnace is 1000mm, and the formed substrate glass needs annealing time of 10 s;

in the slow cooling phase, the temperature range T_mAt 400 ℃ and a slow cooling rate V_mIs 33.08 ℃/s and the running speed V of the glass plate at the slow cooling section of the annealing furnace₀100mm/s, the length L of the slow cooling section of the annealing furnace_m1209 mm;

in the fast cooling phase, the temperature range T_kIs cooled at 300 ℃ and quicklyBut rate V_k132.32 ℃/s and the running speed V of the glass plate at the fast cooling section of the annealing furnace₁Is 100mm/s, and the length L of the fast cooling section of the annealing furnace_kIs 227 mm.

Example 3

After OLED display TFT substrate glass with the thickness of 0.6mm is formed by an overflow method, the annealing process is used for annealing, and the specific process is as follows:

in the stage of heat preservation,the temperature is 60 ℃/s, the length of the heat-preservation section of the annealing furnace is 1200mm, and the formed substrate glass needs to be annealed for 12 s;

in the slow cooling phase, the temperature range T_mAt 400 ℃ and a slow cooling rate V_m23.83 ℃/s and the running speed V of the glass plate at the slow cooling section of the annealing furnace₀100mm/s, the length L of the slow cooling section of the annealing furnace_m1679 mm;

in the fast cooling phase, the temperature range T_kAt 300 ℃ and a rapid cooling rate V_k95.30 ℃/s and the running speed V of the glass plate at the fast cooling section of the annealing furnace₁Is 100mm/s, and the length L of the fast cooling section of the annealing furnace_kIs 315 mm.

Example 4

After OLED display TFT substrate glass with the thickness of 0.7mm is formed by an overflow method, the annealing process is used for annealing, and the specific process is as follows:

in the stage of heat preservation,the temperature of the annealing furnace is 70 ℃/s, the length of the heat-preservation section of the annealing furnace is 1400mm, and the annealing time of the formed substrate glass is 14 s;

in the slow cooling phase, the temperature range T_mAt 400 ℃ and a slow cooling rate V_m18.05 ℃/s and the running speed V of the glass plate at the slow cooling section of the annealing furnace₀100mm/s, the length L of the slow cooling section of the annealing furnace_m2216 mm;

in the fast cooling phase, the temperature range T_kAt 300 ℃ and a rapid cooling rate V_kThe glass plate running speed of the fast cooling section of the annealing furnace is 72.21 ℃/sV₁Is 100mm/s, and the length L of the fast cooling section of the annealing furnace_kIs 415 mm.

TABLE 2

Example 5

LCD display TFT substrate glass with the thickness of 0.4mm is taken and is annealed by the annealing process of the invention after being formed by an overflow method, and the specific process is as follows:

in the stage of heat preservation,the temperature is 40 ℃/s, the length of the heat-preservation section of the annealing furnace is 800mm, and the formed substrate glass needs annealing time of 8 s;

in the slow cooling phase, the temperature range T_mAt 350 ℃ and a slow cooling rate V_mIs 46.83 ℃/s and the running speed V of the glass plate at the slow cooling section of the annealing furnace₀100mm/s, the length L of the slow cooling section of the annealing furnace_m747 mm;

in the fast cooling phase, the temperature range T_kAt 270 ℃ and a rapid cooling rate V_k187.32 ℃/s and the running speed V of the glass plate at the fast cooling section of the annealing furnace₁Is 100mm/s, and the length L of the fast cooling section of the annealing furnace_kIs 144 mm.

Example 6

LCD display TFT substrate glass with the thickness of 0.4mm is taken and is annealed by the annealing process of the invention after being formed by an overflow method, and the specific process is as follows:

in the stage of heat preservation,the temperature is 50 ℃/s, the length of the heat-preservation section of the annealing furnace is 1000mm, and the formed substrate glass needs annealing time of 10 s;

in the slow cooling phase, the temperature range T_mAt 350 ℃ and a slow cooling rate V_m31.34 ℃/s and the running speed V of the glass plate at the slow cooling section of the annealing furnace₀100mm/s, the length L of the slow cooling section of the annealing furnace_m1117 mm;

in the fast cooling phase, the temperature range T_kAt 270 ℃ and a rapid cooling rate V_k125.36 ℃/s and the running speed V of the glass plate at the fast cooling section of the annealing furnace₁Is 100mm/s, and the length L of the fast cooling section of the annealing furnace_kIs 215 mm.

Example 7

LCD display TFT substrate glass with the thickness of 0.6mm is taken and is annealed by the annealing process of the invention after being formed by an overflow method, and the specific process is as follows:

in the stage of heat preservation,the temperature is 60 ℃/s, the length of the heat-preservation section of the annealing furnace is 1200mm, and the formed substrate glass needs to be annealed for 12 s;

in the slow cooling phase, the temperature range T_mAt 350 ℃ and a slow cooling rate V_m22.57 ℃/s and the running speed V of the glass plate at the slow cooling section of the annealing furnace₀100mm/s, the length L of the slow cooling section of the annealing furnace_m1551 mm;

in the fast cooling phase, the temperature range T_kAt 270 ℃ and a rapid cooling rate V_k90.29 ℃/s and the running speed V of the glass plate at the fast cooling section of the annealing furnace₁Is 100mm/s, and the length L of the fast cooling section of the annealing furnace_kIs 299 mm.

Example 8

LCD display TFT substrate glass with the thickness of 0.7mm is taken and is annealed by the annealing process of the invention after being formed by an overflow method, and the specific process is as follows:

in the stage of heat preservation,the temperature of the annealing furnace is 70 ℃/s, the length of the heat-preservation section of the annealing furnace is 1400mm, and the annealing time of the formed substrate glass is 14 s;

in the slow cooling phase, the temperature range T_mAt 350 ℃ and a slow cooling rate V_mIs 17.1 ℃/s and the running speed V of the glass plate at the slow cooling section of the annealing furnace₀100mm/s, the length L of the slow cooling section of the annealing furnace_m2046 mm;

in the fast cooling phase, the temperature range T_kAt 270 ℃ and at a rapid cooling rateRate V_k68.41 ℃/s and the running speed V of the glass plate at the fast cooling section of the annealing furnace₁Is 100mm/s, and the length L of the fast cooling section of the annealing furnace_kIs 395 mm.

The reheating shrinkage rate of the TFT substrate in the embodiments 1-8 is characterized, and is measured according to the standard of GB/T38711-: heating to 600 ℃ at room temperature, keeping the temperature for 3-10min, and measuring the micro-stress of the TFT substrate glass by adopting an industry universal stress birefringence measuring system with the model of Exicor-GEN8.5 and the minimum resolution of 1 PSI.

Finally, the thermal shrinkage of the substrate glass prepared in example 1 was measured to be 7ppm, and the microstress test result was 30 PSI;

the heat shrinkage rate of the substrate glass prepared in example 2 was 6ppm, and the micro-stress detection result was 34 PSI;

the heat shrinkage rate of the substrate glass prepared in example 3 was 5ppm, and the microstress test result was 32 PSI;

the heat shrinkage rate of the substrate glass prepared in example 4 was 8ppm, and the micro stress detection result was 40 PSI;

the heat shrinkage rate of the substrate glass prepared in example 5 was 24ppm, and the microstress test result was 45 PSI;

the heat shrinkage rate of the substrate glass prepared in example 6 was 31ppm, and the microstress test result was 51 PSI;

the heat shrinkage rate of the substrate glass prepared in example 7 was 36ppm, and the microstress test result was 56 PSI;

the substrate glass obtained in example 8 had a heat shrinkage of 45ppm and a microstress test of 60 PSI.

In conclusion, after the process disclosed by the invention is adopted, the annealing quality of the TFT substrate glass produced by an overflow method is greatly improved, the reheating shrinkage rate and the maximum stress value are both reduced by over 75%, the reheating shrinkage rate of the TFT substrate glass for OLED display is 5-8ppm, the reheating shrinkage rate of the TFT substrate glass for LCD display is 24-45ppm, and the maximum stress of the plate surface of the TFT substrate glass is 30-60 PSI.