TW202248155A - Glass substrate, glass base-plate for through-hole formation, and glass substrate manufacturing method - Google Patents

Abstract

This glass substrate includes through-holes and is characterized in that the value of ER/ERa is 1.50 or less when the HF etching rate of the glass substrate is ER and the HF etching rate after the glass substrate has been subjected to a heat treatment is Era.

Description

Glass substrate, original glass plate for forming through-holes, and manufacturing method of glass substrate

The present invention relates to a glass substrate, a glass original plate for forming a through-hole, and a method for manufacturing the glass substrate. Specifically, it relates to a glass substrate having a through hole formed by etching, a glass original plate for forming a through hole, and a method for manufacturing a glass substrate having a through hole.

Glass substrates with through holes are used, for example, in glass interposers or micro light-emitting diode (LED) displays (see Patent Document 1 and Patent Document 2). In these applications, the smaller the diameter of the through-holes on the surface of the glass substrate, the more densely the through-holes can be produced, and thus semiconductors can be mounted on the glass substrate at high density.

As a first method of forming through-holes, there is known a method of forming through-holes by irradiating a glass blank with laser light (see Patent Document 3). As a second method, a method of enlarging the hole diameter by etching after forming an initial through hole by laser is also proposed (see Patent Document 4).

However, the first and second methods form through-holes by thermal processing using lasers, and thus have problems such as cracks in the glass substrate.

Therefore, as a third method, a method of forming a through-hole by removing the modified portion by etching after forming the modified portion by irradiation of laser light has been studied (see Patent Document 5). In addition, since the ultrashort pulse laser is used in the production of the modified part, the thermal influence can be infinitely reduced, so that the above-mentioned problems will not occur.

In addition, in the case of producing the through-hole by the third method, the through-hole has a tapered shape in the thickness direction. In order to produce through-holes at high density, it is important to reduce the taper angle of the through-holes. For this purpose, for example, adding a coloring element to glass has been proposed (see Patent Document 6). [Prior art literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2015-146401 [Patent Document 2] Japanese Patent Application Publication No. 2020-522884 [Patent Document 3] Japanese Patent Laid-Open No. 2016-55295 [Patent Document 4] Japanese Patent No. 5994954 [Patent Document 5] Japanese Patent No. 6333282 [Patent Document 6] Japanese Patent No. 6700201

[Problem to be Solved by the Invention]

In addition, alkali-free glass is widely used in display applications. However, in the case of alkali-free glass, if the through-holes are formed by the third method, the taper angle of the through-holes becomes large, and the hole density cannot be increased. Therefore, it cannot be applied to the use of micro LED displays.

As described in Patent Document 6, in order to reduce the taper angle of the through hole, it is considered to add a coloring element to the glass composition. However, when a coloring element is added, the physical, chemical, and optical properties of glass will change significantly compared to conventional glass, making it difficult to adjust film-forming conditions, for example, in the film-forming process of a panel manufacturer.

An object of the present invention is to provide a glass substrate capable of being used for a display and having a small through-hole taper angle and a method of manufacturing the same, and to provide a through-hole-forming glass original plate capable of reducing the through-hole taper angle. [Means to solve the problem]

As a result of earnest research, the present inventors have found that the above-mentioned technical problems can be solved by limiting the etching rate ratio after heat treatment to a predetermined value or less, and proposed it as the present invention. That is, the glass substrate of the present invention has a through hole, and the glass substrate is characterized in that when the hydrofluoric acid (hydrofluoric acid, HF) etching rate of the glass substrate is set to ER, the HF etching rate after heat-treating the glass substrate is When the rate is ERa, the value of ER/ERa becomes 1.50 or less. Here, the so-called "heat treatment" for evaluating the HF etching rate is to raise the temperature of the glass substrate from 25°C at a rate of 5°C/min to the temperature (slow cooling point Ta + 30°C) of the glass substrate, expressed as (Ta +30°C) for 30 minutes, then lower the temperature to (Ta -170°C) at a rate of 3°C/min, and then cool down to 25°C at a rate of 10°C/min (see Figure 1). The "slow cooling point Ta of the glass substrate" can be measured based on the method of American Society of Testing Materials (ASTM) C336. The "HF etching rate" is a value measured by the following method. First, after optically polishing both surfaces of the sample, a part is masked. Also, 300 mL of a 2.5 mol/L HF solution was stirred at about 600 rpm using a water bath stirrer set at 30°C. Next, the sample was immersed in the HF solution for 20 minutes. Thereafter, the mask was removed, the sample was cleaned, and the step difference between the masked part and the eroded part was measured using Surfcorder (ET4000A: manufactured by Kosaka Laboratories Co., Ltd.). Finally, the etch rate was calculated by dividing this value by the immersion time.

In the case of forming the through-hole by the third method, the taper angle of the through-hole is determined based on the ratio of the expansion rate of the hole diameter on the glass surface to the etching rate in the thickness direction of the reformed portion. Here, the former is considered to be the original etching rate of glass. Therefore, if the ratio of the two etching rates can be changed according to the thermal history of the glass, the taper angle of the through hole can be changed.

In addition, glass physical properties change according to the virtual temperature, for example, density, refractive index, HF etching rate, heat shrinkage rate, infrared (Infrared Radiation, IR) spectrum, Raman spectrum, etc. change according to the virtual temperature. As the virtual temperature becomes lower, the density becomes larger, and the HF etching rate decreases. Therefore, density or HF etching rate can be used as an index representing virtual temperature.

The virtual temperature of the original glass sheet varies greatly depending on the cooling rate during forming. For example, the virtual temperature of the original glass sheet formed by the overflow down draw method is higher than that of the original glass sheet formed by the floating method. In addition, the virtual temperature can also be changed by annealing the formed glass original plate.

As mentioned above, the HF etching rate varies according to the virtual temperature of the original glass. Therefore, it is presumed that the shape of the through hole formed by performing HF etching after laser reforming also changes according to the virtual temperature. The virtual temperature of the original glass will change through the manufacturing steps of the original glass or the subsequent annealing steps, so it is very important to grasp the relationship between the virtual temperature and the taper angle for forming through-holes in the original glass. However, the influence of the virtual temperature of the original glass plate on the taper angle of the through hole has not been known yet.

As a result of diligent research, the present inventors have found that by setting the HF etching rate of the glass substrate (glass original plate) as ER and the HF etching rate after heat treatment as ERa while focusing on the above points, the The value of ER/ERa is limited to 1.50 or less, and a glass substrate having a small taper angle of the through hole can be obtained. In particular, it was found that the value of ER/ERa can be reduced when the virtual temperature of the original glass plate is lowered in advance by annealing or the like.

Moreover, in the glass substrate of this invention, it is preferable that the hole diameter of the through-hole on the surface of a glass substrate is 1 micrometer - 200 micrometers.

In addition, in the glass substrate of the present invention, the average taper angle θ in the thickness direction of the through holes is preferably 0° to 13°. Here, the "average taper angle θ" refers to the taper angle θ1 calculated from the cross-sectional shape of the through-hole from the first surface of the glass substrate to the narrow portion of the through-hole, and the taper angle θ1 calculated from the first surface of the glass substrate. The average value of the taper angle θ2 calculated from the cross-sectional shape of the through-hole from the second opposing surface to the narrow portion of the through-hole (see FIG. 2 ).

In addition, the glass original plate for forming a through-hole according to the present invention is a glass original plate for forming a through-hole for forming a through-hole. When the HF etching rate is ERa, the value of ER/ERa becomes 1.50 or less.

The method for manufacturing a glass substrate of the present invention is characterized in that it includes the steps of preparing a through-hole forming glass original plate for forming a through-hole, and forming a through-hole on the glass original plate to obtain a glass substrate having a through-hole. When the HF etching rate of the substrate is ER, and the HF etching rate after the heat treatment of the glass substrate is ERa, the value of ER/ERa is 1.50 or less.

The method for manufacturing a glass substrate of the present invention is characterized in that it includes the steps of preparing a through-hole forming glass original plate for forming a through-hole, and forming a through-hole on the glass original plate to obtain a glass substrate having a through-hole. When the HF etching rate of the original plate is ER, and the HF etching rate after the heat treatment of the glass original plate is ERa, the value of ER/ERa is 1.50 or less.

Moreover, in the manufacturing method of the glass substrate of this invention, it is preferable that the average taper angle (theta) in the thickness direction of a through-hole is 0 degree-13 degrees.

In addition, it is preferable that the manufacturing method of the glass substrate of this invention further includes the process of annealing a glass original board. Here, the "annealing step" refers to a step in which the temperature of the formed glass raw plate is raised from room temperature to a temperature above the strain point Ps and then lowered to room temperature, not including the cooling treatment during the forming step. [Effect of the invention]

According to the present invention, when the HF etching rate of the glass substrate is ER and the HF etching rate after heat treatment is ERa, if the value of ER/ERa is limited to 1.50 or less, even if no coloring element is introduced into the glass composition etc., a glass substrate with a small taper angle of the through hole can also be obtained. Thereby, the density of the through hole becomes high, and it is suitable for the application of the micro LED display.

In the glass substrate of the present invention, when the HF etching rate of the glass substrate is ER and the HF etching rate after heat treatment is ERa, the value of ER/ERa is 1.50 or less, preferably 1.40 or less, 1.30 or less, 1.20 or less. Below, below 1.15, below 1.14, below 1.13, below 1.12, below 1.11, below 1.10, below 1.09, below 1.08, below 1.07, below 1.06, below 1.05, below 1.04, below 1.03, below 1.02, below 1.01, below 1.00 , 0.99 or less, 0.98 or less, 0.96 or less, especially 0.95 or less. Especially when it is less than 1.12, the effect of reducing the taper angle of the through-hole becomes remarkable. In the original glass plate for through-hole formation of the present invention, when the HF etching rate of the original glass plate is ER and the HF etching rate after heat treatment is ERa, the value of ER/ERa is 1.50 or less, preferably 1.40 or less, 1.30 or less, 1.20 or less, 1.15 or less, 1.14 or less, 1.13 or less, less than 1.12, 1.11 or less, 1.10 or less, 1.09 or less, 1.08 or less, 1.07 or less, 1.06 or less, 1.05 or less, 1.04 or less, 1.03 or less, 1.02 or less, 1.01 Below, below 1.00, below 0.99, below 0.98, below 0.96, especially below 0.95. If ER/ERa is too large, the taper angle of the through hole becomes too large.

As a method of reducing the value of ER/ERa, it is effective to lower the virtual temperature of the original glass sheet by annealing or the like. In particular, annealing the original glass sheet after forming is performed, and off-line annealing is particularly preferable. In addition, it is also effective to delay the drawing speed during forming.

In the glass substrate of the present invention, the average taper angle θ of the through holes is preferably 13° or less, 11° or less, 10° or less, 9° or less, 8° or less, particularly preferably 7° or less. If the average taper angle ?

After the through-holes are formed in the original glass plate by the third method and the glass substrate with the through-holes is produced, in order to realize the conduction between the front and back of the glass substrate, a plating step is required to form a conductive portion on the inner wall of the through-holes. If the average taper angle ? Therefore, the average taper angle θ of the through holes is preferably not less than 0°, not less than 1°, not less than 2°, not less than 3°, and not less than 4°.

The hole diameter of the through hole on the surface of the glass substrate is preferably 200 μm or less, 150 μm or less, 125 μm or less, 100 μm or less, 90 μm or less, 80 μm or less, 70 μm or less, 65 μm or less, 60 μm or less, 55 μm or less, 50 μm or less, 45 μm or less, 40 μm or less, 35 μm or less, particularly preferably 30 μm or less. If the hole diameter is too large, the through-holes cannot be formed on the glass substrate with a high density, and it is difficult to increase the pixel density of the display. On the other hand, if the hole diameter is too small, it will be difficult to fill the inside of the hole with plating. Therefore, the pore diameter is preferably at least 1 μm, at least 5 μm, at least 10 μm, and at least 15 μm, particularly preferably at least 20 μm.

Next, a method of evaluating the taper angle of the through hole will be described. 2 is a schematic cross-sectional view showing a glass substrate having a through-hole according to an embodiment of the present invention. In FIG. 2 , the average taper angle θ of the through-holes 20 is a value calculated from Equation 1 below. θ=(θ1+θ2)/2 ・・・ Formula 1 In addition, the taper angle θ1 and the taper angle θ2 can be calculated according to Equation 2 and Equation 3 below. θ1=arctan((Φ1-Φ3)/(2*t1)) ・・・ Formula 2 θ2=arctan((Φ2-Φ3)/(2*t2)) ・・・ Formula 3

The value necessary for the calculation of the average taper angle θ can be measured by the following method. The apertures Φ1 and Φ2 of the first surface 101 and the second surface 102 can be obtained by observing the surface of the glass substrate with a transmission optical microscope (such as ECLIPSE LV100ND: manufactured by Nikon Corporation) and measuring the length according to the images. Determination. The diameter Φ3 of the narrow portion of the through hole 20, the distance t1 from the first surface 101 to the narrow portion, and the distance t2 from the second surface 102 to the narrow portion can be shifted to The inside of the glass is used to focus and measure the length based on the image. At this time, it is desirable to obtain a cross section by scribing the glass substrate 100 so that the through hole 20 is not exposed to the cross section, and breaking it.

In addition, the average taper angle θ can be calculated similarly even for non-through holes. Fig. 3 is a schematic cross-sectional view of an original glass plate before forming through-holes. The taper angle θ1 and the taper angle θ2 at this time can be calculated according to the following equations 4 and 5. The average cone angle θ can be calculated using the cone angle θ1 and the cone angle θ2 with Equation 1. θ1=arctan(Φ1/(2*t1)) ・・・ Formula 4 θ2=arctan(Φ2/(2*t2)) ・・・ Formula 5

The hole diameters Φ1 and Φ2 of the first surface 101 and the second surface 102 , and the hole depths t1 and t2 can be measured from images obtained by a transmission optical microscope, as in the case of through holes.

The hole diameter Φ1, hole diameter Φ2, hole depth t1, and hole depth t2 of the first surface 101 and the second surface 102 are defined in the same manner as in the case of the through hole. In addition, when the through hole 20 does not have a narrow portion inside the glass, the average The taper angle θ is defined as follows. FIG. 4 is a schematic cross-sectional view of a glass substrate including a through-hole 20 that does not have a narrow portion inside the glass. The average taper angle θ at this time is defined as a value calculated from Equation 6. The aperture diameter Φ1, the aperture diameter Φ2, and the plate thickness t of the first surface 101 and the second surface 102 can be measured by measuring lengths from images obtained using a transmission optical microscope in the same manner as described above. θ=arctan((Φ1-θ2)/(2*t)) ・・・ Formula 6

Next, a method of forming a through-hole in a glass original plate will be described. The modified part can be formed by irradiating a femtosecond or picosecond pulse wave laser to the original glass plate. Laser wavelengths below 1030 nm can be used.

Furthermore, as the beam shape of the laser, a Gaussian beam (Gaussian beam) shape or a Bessel beam (Bessel beam) shape can be used. Among them, it is preferable to use a Bessel beam shape. With the Bessel beam shape, the modified portion can be formed penetrating in the plate thickness direction by one irradiation, and the time required for producing the modified portion can be shortened. Bessel beam shapes can be formed, for example, by using an axicon lens.

The type of etchant used for etching the reformed part is not particularly limited as long as the etching rate of the reformed part is faster than that of the original glass plate. For example, HF and buffered hydrofluoric acid (Buffered HydroFluoric, BHF) can be used. , KOH, etc. In particular, HF is preferable because it can increase the etching rate and shorten the time required for the formation of through holes. In addition, one or more acids such as HCl, H ₂ SO ₄ , and HNO ₃ may be selected and added to the HF solution to form a mixed solution.

The temperature of the etching solution is not particularly limited, but it is effective to increase the temperature. In the case of the etchant containing HF, the temperature range is preferably 0°C to 50°C, more preferably 20°C to 40°C. When the temperature of the etchant is increased, the rate of increase in the etching rate of the modified portion is greater than that of the original glass plate. Therefore, the time required for forming the through-hole can be shortened, and thus the amount of reduction in plate thickness can be reduced. On the other hand, if the temperature of the etchant is too high, HF volatilizes, resulting in uneven concentration of HF in the etchant, and large variations in pore shape.

The longer the etching time, the larger the average taper angle θ. This is based on the following reasons. Residue generated by etching accumulates inside the hole during formation, and this residue hinders etching in the extending direction of the hole. Therefore, the taper angle of the through hole gradually increases as the etching time increases. Therefore, the etching time is preferably not more than 100 minutes, not more than 60 minutes, not more than 40 minutes, and not more than 30 minutes, particularly preferably not more than 20 minutes. Furthermore, when the virtual temperature of the original glass plate is lowered, the HF etching rate is lowered, and the amount of residue generated per unit time is reduced, so that the increase rate of the taper angle can be reduced.

It is preferable to apply stirring or ultrasonic wave of an etchant when performing etching of a glass original plate. In particular, by applying ultrasonic waves, the fixation and reattachment of residues on the inner wall of the hole can be suppressed. The frequency of ultrasonic waves is preferably at most 100 kHz, more preferably at most 45 kHz. If the frequency is in such a range, the effect of pitting corrosion by ultrasonic waves can be increased.

In the glass substrate (or original glass plate) of the present invention, the glass composition preferably contains 50% to 70% of SiO ₂ , 12% to 25% of Al ₂ O ₃ , 0% to 12% of B ₂ O ₃ , Li ₂ O+Na ₂ O+K ₂ O (total amount of Li ₂ O, Na ₂ O and K ₂ O) of less than 0% to 1%, MgO of 0% to 8%, 0 % to 15% of CaO, 0% to 12% of SrO, and 0% to 15% of BaO, among which the following glass composition examples (1) to glass composition examples (4) are particularly preferred. If so, it is suitable as a glass substrate for displays. (1) Preferably, as a glass composition, 50% to 70% of SiO ₂ , 12% to 22% (especially 15% to 20%) of Al ₂ O ₃ , 7% to 15% ( Especially 6% to 10%) B ₂ O ₃ , less than 0% to 1% (especially 0% to 0.5%) Li ₂ O+Na ₂ O+K ₂ O, 0% to 3% MgO , 6% to 13% (especially 6% to 9%) of CaO, 0.1% to 5% (especially 0.1% to 3%) of SrO, 3% to 10% (especially 4% to 7%) of BaO. If so, the liquid phase viscosity can be increased while lowering the melting temperature. As a result, the manufacturing cost of a glass substrate can be reduced. (2) Preferably, as a glass composition, 58% to 68% of SiO ₂ , 15% to 23% (especially 17% to 21%) of Al ₂ O ₃ , 3% to 9% ( Especially 3% to 5%) of B ₂ O ₃ , less than 0% to 1% (especially 0% to 0.5%) of Li ₂ O+Na ₂ O+K ₂ O, 0% to 6% (especially 1% to 4%) of MgO, 3% to 13% (especially 5% to 10%) of CaO, 0% to 10% (especially 0.1% to 3%) of SrO, 0.1% to 5% of BaO. If so, the liquid viscosity and Young's modulus can be increased. As a result, it is easy to produce a thin glass substrate, and furthermore, it is easy to reduce the amount of warping of the glass substrate. (3) Preferably, the glass composition contains, by mass %, 58% to 65% of SiO ₂ , 18% to 23% of Al ₂ O ₃ , 0% to 3% (especially less than 0.1% to 1% ) of B ₂ O ₃ , less than 0% to 1% (especially 0% to 0.5%) of Li ₂ O+Na ₂ O+K ₂ O, 0.1% to 6% (especially 2% to 5%) MgO of 2% to 7% (especially 4% to 6%) of CaO, 0% to 5% of SrO, and BaO of 2% to 15% (especially 5% to 10%). If so, it becomes easy to raise a strain point to 730 degreeC or more. (4) Preferably, the glass composition contains 60% to 70% (especially 65% to 70%) of SiO ₂ and 7% to 20% (especially 7% to 16%) of Al ₂ in mass % O ₃ , 0% to 8% (especially 2% to 8%) of B ₂ O ₃ , less than 0% to 1% (especially 0% to 0.5%) of Li ₂ O+Na ₂ O+K ₂ O, 0%-10% (especially 0.1%-5%) MgO, 0%-7% CaO, 0%-7% SrO, 0%-15% BaO. If so, it is easy to reduce the HF etching rate. As a result, it is easy to reduce the amount of residue generated when forming a through-hole by HF etching, and it is easy to reduce the taper angle of the through-hole.

The total or individual content of oxides of at least one metal selected from the group consisting of Fe, Ce, Bi, W, Mo, Co, Mn, Cr, V, and Cu is preferably less than 1%, less than 0.1%, especially less than 0.01%. In addition, the content of TiO ₂ is preferably less than 1%, less than 0.1%, particularly preferably less than 0.01%. When the content of these components is too large, the physical properties, chemical properties, and optical properties vary greatly, and it becomes difficult to adjust film-forming conditions and the like in a film-forming process by a panel manufacturer, for example.

The glass substrate (original glass plate) of the present invention preferably has the following properties.

The average thermal expansion coefficient in the temperature range of 30°C to 380°C is preferably 30×10 ^-7 /°C to 50×10 ^-7 /°C, more preferably 32×10 ^-7 /°C to 48×10 ^-7 /°C , more preferably 33×10 ^-7 /℃～45×10 ^-7 /℃, more preferably 34×10 ^-7 /℃～44×10 ^-7 /℃, most preferably 35×10 ^-7 /℃～ 43×10 ^-7 /°C. If so, it is easy to match with the thermal expansion coefficient of Si used in thin film transistors (Thin Film Transistor, TFT). In addition, "the average thermal expansion coefficient in the temperature range of 30 degreeC - 380 degreeC" is the value measured with the dilatometer (dilatometer).

The Young's modulus is preferably at least 65 GPa, more preferably at least 70 GPa, more preferably at least 75 GPa, more preferably at least 77 GPa, particularly preferably at least 78 GPa. When the Young's modulus is too low, defects due to deflection of the glass substrate are likely to occur. In addition, "Young's modulus" means the value measured by the well-known resonance method.

The strain point is preferably at least 650°C, more preferably at least 680°C, even more preferably at least 686°C, particularly preferably at least 690°C. If so, thermal shrinkage of the glass substrate can be suppressed during the TFT manufacturing process. In addition, a "strain point" is a value measured based on the method of American Society of Testing Materials (ASTM) C336.

The liquidus temperature is preferably at most 1350°C, more preferably less than 1350°C, more preferably at most 1300°C, particularly preferably from 1000°C to 1280°C. The liquid phase viscosity is preferably at least ^104.0 dPa･s, more preferably at least ^104.1 dPa･s, more preferably at least ^104.2 dPa･s, most preferably at least ^104.3 dPa･s. In this way, it is easy to prevent a situation in which devitrified crystals are generated during molding to lower productivity. Furthermore, since molding by the overflow down-draw method is easy, the surface quality of a glass substrate can be improved easily, and the manufacturing cost of a glass substrate can be reduced. In addition, the liquidus temperature is an indicator of devitrification resistance, and the lower the liquidus temperature is, the more excellent the devitrification resistance is. "Liquidus temperature" is the temperature at which crystallization occurs after passing through a standard sieve of 30 mesh (500 μm) and remaining in a 50 mesh (300 μm) glass powder into a platinum boat and keeping it in a temperature gradient furnace for 24 hours. The "liquidus viscosity" is a value obtained by measuring the viscosity of glass at the liquidus temperature TL by the platinum ball pulling method.

The temperature at a high temperature viscosity of 10 ^2.5 dPa･s is preferably below 1700°C, more preferably below 1690°C, more preferably below 1680°C, most preferably at 1400°C to 1670°C. If the temperature at the high-temperature viscosity of 10 ^2.5 dPa･s is too high, it will be difficult to melt the glass batch and the manufacturing cost of the glass substrate will increase. Furthermore, the temperature at a high-temperature viscosity of 10 ^2.5 dPa･s corresponds to the melting temperature, and the lower the temperature, the better the meltability. In addition, the "temperature at a high temperature viscosity of 10 ^2.5 dPa･s" can be measured by, for example, a platinum ball pulling method or the like.

The glass substrate (original glass plate) of the present invention is preferably formed by an overflow down-draw method. The overflow down-draw method is a method in which molten glass overflows from both sides of a heat-resistant trough-like structure, and the overflowing molten glass converges at the lower end of the trough-like structure while stretching downward to form a glass original plate. In the overflow downdraw method, the surface to be the surface of the original glass plate is formed in a free surface state without contacting the groove-shaped refractory. Therefore, an unpolished glass base plate with good surface quality can be manufactured inexpensively, and thinning is also easy.

In addition to the overflow down-draw method, for example, the glass original sheet can also be formed by a down-draw method (slot down draw method, etc.), a floating method, or the like.

In the glass substrate (original glass plate) of the present invention, the plate thickness is not particularly limited, but is preferably less than 0.7 mm, less than 0.6 mm, less than 0.6 mm, less than 0.5 mm, less than 0.4 mm, less than 0.3 mm, and less than 0.2 mm. Below, and preferably more than 0.01 mm, more than 0.05 mm, more than 0.1 mm. The most preferred range is 0.05 mm to 0.5 mm. The thinner the plate thickness, the smaller the diameter of the through hole. As a result, through-holes can be formed at high density. On the other hand, when the plate thickness becomes too thin, the glass substrate becomes easily damaged. In addition, the plate thickness can be adjusted by the flow rate during forming, the drawing speed, and the like.

The glass substrate of the present invention is preferably a substrate for a micro LED display, especially a tiled micro LED display. In the tiled micro-LED display, by realizing conduction between the front and back of the glass substrate through the through hole, the light emitting elements on the glass surface can be driven from the back of the glass. The glass substrate of the present invention can produce through-holes with high density, so it can make the tiled micro-LED display highly refined.

The method for manufacturing a glass substrate of the present invention is characterized in that it includes the steps of preparing a glass original plate for forming a through-hole, and forming a through-hole on the glass original plate to obtain a glass substrate with a through-hole. When the HF etching rate is ER, and the HF etching rate after the heat treatment of the glass substrate is ERa, the value of ER/ERa is 1.50 or less. The method for manufacturing a glass substrate of the present invention is characterized in that it includes the steps of preparing a glass original plate for forming a through-hole, and forming a through-hole on the glass original plate to obtain a glass substrate with a through-hole, and setting the HF etching rate of the glass original plate to ER is ER, and when the HF etching rate after heat-treating the original glass plate is ERa, the value of ER/ERa is 1.50 or less. As a method of reducing the value of ER/ERa, it is effective to lower the virtual temperature of the original glass sheet by annealing or the like. In particular, annealing the original glass sheet after forming is performed, and off-line annealing is particularly preferable. In addition, it is also effective to delay the drawing speed during forming. In addition, since the technical feature of the manufacturing method of the glass substrate of this invention is already described in description of the glass substrate of this invention, detailed description is abbreviate|omitted here. [Example]

Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these Examples.

(Example 1) First, prepare an alkali-free glass original plate with a thickness of 500 μm (trade name OA-11 manufactured by NEC Glass Co., Ltd., slow cooling point Ta 743°C), and perform off-line annealing from room temperature (25°C) according to the temperature curve shown in Figure 5 , Determination of the density and HF etching rate (ER) of the alkali-free glass original plate. Furthermore, this alkali-free glass original plate was heat-processed from room temperature (25 degreeC) according to the temperature profile shown in FIG. 5, and the HF etching rate (ERa) was measured.

The density is a value measured by the well-known Archimedes method.

The HF etching rate is a value measured by the following method. First, after optically polishing both surfaces of the sample, a part is masked. For 300 mL of 2.5 mol/L HF solution, use a water-bath stirrer set at 30°C and stir at about 600 rpm. The base plate of non-alkali glass was immersed in this HF solution for 20 minutes. Thereafter, the mask was removed, the sample was cleaned, and the step difference between the masked part and the eroded part was measured using Surfcorder (ET4000A: manufactured by Kosaka Laboratories Co., Ltd.). The etch rate was calculated by dividing this value by the immersion time.

Next, with respect to the non-alkali glass original plate which performed off-line annealing with the temperature profile shown in FIG. 5, the through-hole was formed by the following method, and the non-alkali glass substrate which has a through-hole was obtained. A non-alkali glass original plate cut into a rectangular shape of 40 mm × 20 mm is irradiated with a femtosecond pulse wave laser shaped into a Bessel beam shape at a pitch interval of about 200 μm to form an alkali-free glass original plate. About 8000 modified parts.

Next, the non-alkali glass original plate was etched by wet etching under the following conditions. The etching time was set to 15 minutes and 30 minutes. A non-alkali glass original plate is placed in a test tube made of polypropylene (PP) containing an etchant, and ultrasonic waves are applied to the etchant to perform etching. At this time, the non-alkali glass original plate was fixed with a distance of 10 mm from the bottom of the test tube using a jig made of Teflon. As an etching solution, an etching solution containing HF at a concentration of 2.5 mol/L and HCL at a concentration of 1.0 mol/L was used. The temperature of the etching solution was set at 30°C. In order to prevent temperature rise during ultrasonic application, the water in the ultrasonic device was circulated using a cooler, and the water temperature was kept at 30°C. When applying ultrasonic vibration, an ultrasonic cleaning machine (VS-100III: manufactured by ASONE Co., Ltd.) was used, and ultrasonic waves of 28 kHz were applied to the etching solution. The taper angle of the hole thus formed is determined by the method described above.

(Example 2) A 500 μm-thick alkali-free glass original plate (trade name OA-11 manufactured by NEC Glass Co., Ltd.) was prepared, and the density and HF etching rate (ER) were measured without annealing. Furthermore, this alkali-free glass original plate was heat-processed from room temperature (25 degreeC) according to the temperature profile shown in FIG. 5, and the HF etching rate (ERa) was measured. Moreover, the formation of the hole was performed by the method similar to Example 1 about this non-alkali glass original board (it was not heat-processed).

Table 1 shows the densities and HF etching rates of the non-alkali glass substrates of Examples 1 and 2, and Table 2 shows the hole shapes of the non-alkali glass substrates of Examples 1 and 2.

[Table 1] Example 1 Example 2 Density d (g/cm ³ ) 2.5197 2.5126 HF etching rate ER (μm/min) 0.89 1.00 HF etching rate ERa after heat treatment (μm/min) 0.89 0.89 ER/ERa 1.00 1.12

[Table 2] Example 1 Example 2 Etching time (min) 15 30 15 30 hole shape Non-penetrating run through Non-penetrating Non-penetrating Average cone angle θ (°) ((θ1+θ2)/2) 6.5 8.1 6.7 9.1 Cone angle θ1 (°) 6.7 8.2 6.2 8.6 Cone angle θ2 (°) 6.2 8.0 7.1 9.5 Aperture Φ1 (μm) 33 63 37 66 Aperture Φ2 (μm) 33 61 33 59 Through hole diameter Φ3 (μm) - 3 - - Pore depth t1 (μm) 141 209 169 220 Pore depth t2 (μm) 150 209 132 174 Plate thickness before etching (μm) 500 500 500 500 Plate thickness after etching (μm) 458 419 457 419

According to Table 1 and Table 2, when the virtual temperature of the alkali-free glass original plate is low, the etching rate ERa of the alkali-free glass original plate after heat treatment decreases, and the value of ER/ERa becomes smaller. As a result, the average taper angle θ of the through holes becomes smaller.

In the above, the value of ER/ERa was evaluated for the alkali-free glass substrate without holes, and the ER value was evaluated for the alkali-free glass substrate of Example 1 (glass substrate without heat-treated through-holes) with through-holes formed. /ERa, the result is that the value of ER and ERa is 0.89, and the value of ER/ERa is 1.00. In addition, the value of ER/ERa was evaluated for the non-alkali glass substrate of Example 2 (the non-alkali glass substrate having through holes without heat treatment) after the through-holes were formed. As a result, the value of ER was 1.00, and the value of ERa was 0.89, and the value of ER/ERa was 1.12.

(Example 3) First, prepare an alkali-free glass original plate with a thickness of 500 μm (trade name OA-11 manufactured by NEC Glass Co., Ltd., slow cooling point Ta 743°C), and perform off-line annealing from room temperature (25°C) according to the temperature curve shown in Figure 6 , Determining the HF etching rate (ER) of the alkali-free glass original plate. Furthermore, this alkali-free glass original plate was heat-processed from room temperature (25 degreeC) according to the temperature profile shown in FIG. 5, and the HF etching rate (ERa) was measured. Moreover, hole formation was performed by the method similar to Example 1 about this non-alkali glass original plate (annealed and not heat-processed).

(Example 4) First, prepare an alkali-free glass original plate with a thickness of 500 μm (trade name OA-11 manufactured by NEC Glass Co., Ltd., slow cooling point Ta 743°C), and perform off-line annealing from room temperature (25°C) according to the temperature curve shown in Figure 7 , Determining the HF etching rate (ER) of the alkali-free glass original plate. Furthermore, this alkali-free glass original plate was heat-processed from room temperature (25 degreeC) according to the temperature profile shown in FIG. 5, and the HF etching rate (ERa) was measured. Moreover, hole formation was performed by the method similar to Example 1 about this non-alkali glass original plate (annealed and not heat-processed).

(Example 5) First, prepare an alkali-free glass original plate with a thickness of 500 μm (trade name OA-11 manufactured by NEC Glass Co., Ltd., slow cooling point Ta 743°C), and perform off-line annealing from room temperature (25°C) according to the temperature curve shown in Figure 8 , Determining the HF etching rate (ER) of the alkali-free glass original plate. Furthermore, this alkali-free glass original plate was heat-processed from room temperature (25 degreeC) according to the temperature profile shown in FIG. 5, and the HF etching rate (ERa) was measured. Moreover, hole formation was performed by the method similar to Example 1 about this non-alkali glass original plate (annealed and not heat-processed).

Table 3 shows the HF etching rates of the non-alkali glass original plates of Examples 3 to 5, and further shows the hole shapes of the non-alkali glass substrates of Examples 3 to 5.

[table 3] Example 3 Example 4 Example 5 Density d (g/cm3) 2.5183 2.5160 2.5131 HF etching rate ER (μm/min) 0.93 0.94 0.97 HF etching rate ERa after heat treatment (μm/min) 0.89 0.89 0.89 ER/ERa 1.04 1.06 1.09 Etching time (min) 30 30 30 hole shape Non-penetrating Non-penetrating Non-penetrating Average cone angle θ (°) ((θ1+θ2)/2) 8.3 8.6 8.9 Cone angle θ1(°) 7.9 8.7 8.7 Cone angle θ2 (°) 8.6 8.5 9.1 Aperture Φ1 (μm) 60 65 65 Aperture Φ2 (μm) 57 61 66 Through hole diameter Φ3 (μm) - - - Pore depth t1 (μm) 216 215 212 Pore depth t2 (μm) 189 203 206 Plate thickness before etching (μm) 500 500 500 Plate thickness after etching (μm) 419 419 419

According to Table 3, when the cooling rate during annealing is delayed, the virtual temperature of the original non-alkali glass (e-glass substrate) decreases, the etching rate ER of the original non-alkali glass decreases, and the value of ER/ERa becomes smaller. As a result, the average taper angle θ of the holes becomes smaller.

In the above, the value of ER/ERa was evaluated for the non-alkali glass substrate with no holes formed, and for the non-alkali glass substrate of Example 3 (the non-alkali glass substrate with the non-heat-treated through holes) after the through-holes were formed. The value of ER/ERa was calculated. As a result, the value of ER was 0.93, the value of ERa was 0.89, and the value of ER/ERa was 1.04. In addition, the value of ER/ERa was evaluated for the non-alkali glass substrate of Example 4 (the non-alkali glass substrate having through holes without heat treatment) after the through-holes were formed. As a result, the value of ER was 0.94, and the value of ERa was 0.89, and the value of ER/ERa was 1.06. Furthermore, the value of ER/ERa was evaluated for the non-alkali glass substrate of Example 5 (the non-alkali glass substrate having through holes without heat treatment) after the through-holes were formed, and the value of ER was 0.97, and the value of ERa was 0.97. 0.89, and the value of ER/ERa was 1.09.

Furthermore, in Examples 2 to 5, it can be understood that the holes formed in the original non-alkali glass plate are non-through, but even if the etching time is prolonged in order to form through holes, if the ER/ERa ratio is reduced The value can also reduce the average cone angle θ of the hole. Furthermore, according to Table 3, when performing off-line annealing with respect to the non-alkali glass original board for forming a through-hole, it is preferable that a cooling rate is slow. This result shows that even without off-line annealing, the taper angle of the through-hole can be reduced by adjusting the forming conditions such as making the drawing speed slower than usual when forming by the overflow down-draw method.

(Example 6) First, a 500 μm-thick alkali-free glass original plate (NEC Glass Co., Ltd., trade name OA-11, slow cooling point Ta 743°C) was prepared, and off-line annealing was performed according to the following temperature profile. First, put the original plate of alkali-free glass in the annealer, raise the temperature from room temperature (25°C) to 885°C at a rate of 5°C/s, and keep it at 885°C for 10 minutes, then take out the original plate of alkali-free glass from the annealer and place it in the Air cool to room temperature on carbon plates. Then, the HF etching rate (ER) of the obtained original glass plate was measured. Furthermore, this alkali-free glass original plate was heat-processed from room temperature (25 degreeC) according to the temperature profile shown in FIG. 5, and the HF etching rate (ERa) was measured. Moreover, hole formation was performed by the method similar to Example 1 about this non-alkali glass original plate (annealed and not heat-processed).

Table 4 shows the density and HF etching rate of the non-alkali glass substrate of Example 6, and Table 5 shows the hole shape of the non-alkali glass substrate of Example 6.

[Table 4] Example 6 Density d (g/cm ³ ) 2.5106 HF etching rate ER (μm/min) 1.02 HF etching rate ERa after heat treatment (μm/min) 0.89 ER/ERa 1.15

[table 5] Example 6 Etching time (min) 15 30 hole shape Non-penetrating Non-penetrating Average cone angle θ (°) ((θ1+θ2)/2) Not determined Not determined Cone angle θ1(°) Not determined Not determined Cone angle θ2 (°) Not determined Not determined Aperture Φ1 (μm) Not determined Not determined Aperture Φ2 (μm) Not determined Not determined Through hole diameter Φ3 (μm) Not determined Not determined Pore depth t1 (μm) Not determined Not determined Pore depth t2 (μm) Not determined Not determined Plate thickness before etching (μm) Not determined Not determined Plate thickness after etching (μm) Not determined Not determined

As can be seen from Table 4, the value of ER of the alkali-free glass original plate of Example 6 is 1.02, the value of ERa is 0.89, and the value of ER/ERa is 1.15. From this result, it can be seen that the value of ER/ERa increases when performing annealing including the step of quenching the original non-alkali glass plate. In addition, it can also be seen that when forming by the overflow down-draw method, floating method, etc., if the forming conditions are adjusted such that the drawing speed is faster than usual for the purpose of improving productivity or thinning the sheet, the value of ER/ERa becomes large. . In addition, the non-alkali glass original plate of Example 6 had a larger value of ER/ERa than the non-alkali glass original plates of Examples 1 to 5, so the taper angle of the through-hole was expected to be large.

In the above, the value of ER/ERa was evaluated for the non-alkali glass substrate without holes, and the non-alkali glass substrate of Example 6 (the non-alkali glass substrate with the non-heat-treated through holes) after the through holes were formed. The value of ER/ERa was calculated. As a result, the value of ER was 1.02, the value of ERa was 0.89, and the value of ER/ERa was 1.15.

(Example 7) First, prepare an alkali-free glass original plate with a thickness of 500 μm (trade name OA-31 manufactured by NEC Glass Co., Ltd., slow cooling point Ta 809°C), and perform off-line annealing from room temperature (25°C) according to the temperature curve shown in Figure 9 , Determination of the density and HF etching rate (ER) of the alkali-free glass original plate. Furthermore, this non-alkali glass original plate was heat-processed from room temperature (25 degreeC) according to the temperature profile shown in FIG. 9, and the HF etching rate (ERa) was measured. Moreover, hole formation was performed by the method similar to Example 1 about this non-alkali glass original plate (annealed and not heat-processed).

(Example 8) First, a 500 μm-thick alkali-free glass original plate (trade name OA-31 manufactured by NEC Glass Co., Ltd., slow cooling point Ta 809°C) was prepared, and the density and HF etching rate (ER) were measured without annealing. Furthermore, this non-alkali glass original plate was heat-processed from room temperature (25 degreeC) according to the temperature profile shown in FIG. 9, and the HF etching rate (ERa) was measured. Moreover, the formation of the hole was performed by the method similar to Example 1 about this non-alkali glass original board (it was not heat-processed).

Table 6 shows the densities and HF etching rates of the non-alkali glass substrates of Example 7 and Example 8, and Table 7 shows the hole shapes of the non-alkali glass substrates of Example 7 and Example 8.

[Table 6] Example 7 Example 8 Density d (g/cm ³ ) 2.6358 2.6263 HF etching rate ER (μm/min) 0.76 0.85 HF etching rate ERa after heat treatment (μm/min) 0.76 0.76 ER/ERa 1.00 1.12

[Table 7] Example 7 Example 8 Etching time (min) 15 30 15 30 hole shape Non-penetrating Non-penetrating Non-penetrating Non-penetrating Average cone angle θ (°) ((θ1+θ2)/2) 6.4 7.0 6.6 7.3 Cone angle θ1 (°) 6.2 7.0 6.0 7.3 Cone angle θ2 (°) 6.6 7.0 7.2 7.3 Aperture Φ1 (μm) 29 52 28 55 Aperture Φ2 (μm) 29 51 29 54 Through hole diameter Φ3 (μm) - - - - Pore depth t1 (μm) 133 211 134 215 Pore depth t2 (μm) 124 209 116 212 Plate thickness before etching (μm) 500 500 500 500 Plate thickness after etching (μm) 474 444 472 440

According to Table 6 and Table 7, when the virtual temperature of the alkali-free glass original plate is low, the etching rate ERa of the alkali-free glass original plate after heat treatment decreases, and the value of ER/ERa becomes smaller. As a result, the average taper angle θ of the holes becomes smaller.

In the above, the value of ER/ERa was evaluated for an alkali-free glass substrate without holes, and for the alkali-free glass substrate of Example 7 (an alkali-free glass substrate without heat-treated through-holes) after holes were formed. The value of ER/ERa, the result is that the value of ER and ERa is 0.76, and the value of ER/ERa is 1.00. In addition, the value of ER/ERa was evaluated for the non-alkali glass substrate of Example 8 (the non-alkali glass substrate having through-holes without heat treatment) after the hole was formed. As a result, the value of ER was 0.85 and the value of ERa was 0.85. 0.76, and the value of ER/ERa was 1.12.

According to the results of Example 1, Example 2, Example 7, and Example 8, it can be seen that when the virtual temperature of the original glass plate is reduced to reduce the value of ER/ERa, the average hole average value can be reduced regardless of the type of glass. Cone angle θ.

In addition, it was confirmed that T2X-1 (manufactured by NEC Glass Co., Ltd., slow cooling point Ta 614°C) and BDA (manufactured by NEC Glass Co., Ltd., slow cooling point Ta 573°C) formed by the overflow downdraw method were used as In the case of an alkali-containing original glass plate, the average taper angle of the holes can be reduced when the value of ER/ERa is reduced by the same test as in Example 1 and Example 2. That is, when the value of ER/ERa is reduced, the average taper angle θ of the holes can be reduced regardless of the type of glass.

20: Through hole 21: Non-through hole 100: Glass substrate (glass original plate) 101: The first side 100: second side t: board thickness t1, t2: distance, hole depth θ: average cone angle θ1, θ2: cone angle Φ1, Φ2: aperture Φ3: Diameter, hole diameter of through part

Fig. 1 is a graph showing the temperature profile of the heat treatment prior to the measurement of the HF etch rate ERa. 2 is a schematic cross-sectional view showing a glass substrate having a through-hole according to an embodiment of the present invention. Fig. 3 is a schematic cross-sectional view of an original glass plate before forming through-holes. 4 is a schematic cross-sectional view of a glass substrate having a through-hole according to an embodiment of the present invention. Fig. 5 is a temperature graph of the heat treatment of the original non-alkali glass plate (the non-alkali glass substrate). Fig. 6 is a temperature profile of the annealing of the original non-alkali glass plate of [Example 3]. Fig. 7 is a temperature profile of the annealing of the original non-alkali glass plate of [Example 4]. Fig. 8 is a temperature profile of the annealing of the original non-alkali glass plate of [Example 5]. Fig. 9 is a temperature profile of the annealing of the non-alkali glass original plate of [Example 8].

20: Through hole

100: glass substrate (glass original plate)

101: The first side

102: The second side

t1, t2: distance, hole depth

θ1, θ2: cone angle

Φ1, Φ2: aperture

Φ3: Diameter, hole diameter of through hole

Claims (8)

A kind of glass substrate, has through hole, and described glass substrate is characterized in that, when the hydrofluoric acid etching rate of glass substrate is set as ER, when the hydrofluoric acid etching rate after heat treatment is carried out to described glass substrate is set as ERa, The value of ER/ERa was 1.50 or less. The glass substrate according to claim 1, wherein the diameter of the through hole on the surface of the glass substrate is 1 μm to 200 μm. The glass substrate according to claim 1 or claim 2, wherein the average taper angle θ in the thickness direction of the through hole is 0° to 13°. A glass original plate for forming a through hole, which is a glass original plate for forming a through hole, characterized in that, when the hydrofluoric acid etching rate of the glass original plate is set as ER, the glass original plate is heat-treated When the hydrofluoric acid etching rate is ERa, the value of ER/ERa is 1.50 or less. A method for manufacturing a glass substrate, comprising the steps of: preparing a through-hole forming glass original plate for forming the through-hole; and Form through-holes in the original glass plate to obtain a glass substrate with through-holes, And when the hydrofluoric acid etching rate of a glass substrate is ER, and the hydrofluoric acid etching rate after heat-processing the said glass substrate is ERa, the value of ER/ERa becomes 1.50 or less. A method for manufacturing a glass substrate, comprising the steps of: preparing a through-hole forming glass original plate for forming the through-hole; and Form through-holes in the original glass plate to obtain a glass substrate with through-holes, And when the hydrofluoric acid etching rate of a glass original plate is ER, and the hydrofluoric acid etching rate after heat-processing the said glass original plate is ERa, the value of ER/ERa becomes 1.50 or less. The method for manufacturing a glass substrate according to Claim 5 or Claim 6, wherein the average taper angle θ in the thickness direction of the through hole is 0° to 13°. The method for manufacturing a glass substrate according to any one of claim 5 to claim 7 further includes the step of annealing the original glass plate.

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