glass plate

Abstract

This method provides a glass plate in which the depth of the recesses or the height of the protrusions on the inner surface of the through-hole are uniform. [Solution] In a glass plate 1 having an elliptical through-hole 4 with irregularities on its inner surface 10, the region of the inner surface 10 of the through-hole 4 located at the intersection with the major axis 7 is defined as the major axis end region 11, and the region located at the intersection with the minor axis 8 is defined as the minor axis end region 12. The ratio (RPL / RPS) of the parallel roughness of the major axis end region RPL, calculated based on the arithmetic mean roughness of the major axis end region 11, and the parallel roughness of the minor axis end region RPS, calculated based on the arithmetic mean roughness of the minor axis end region 12, is set to be between 0.2 and 2.0. In this glass plate 1, because the difference in the size of the irregularities between the region around the intersection with the major axis 7 and the region around the intersection with the minor axis 8 on the inner surface 10 is small, the depth of the recesses or the height of the protrusions on the inner surface of the through-hole can be made uniform.

Description

Technical Field

[0001] The present disclosure relates to a glass plate in which through holes are formed.

Background Art

[0002] In some cases, a glass plate with through electrodes formed therein is used as a core substrate or an interposer of a semiconductor package. In the glass plate, minute through holes (vias) penetrating from the front surface to the back surface of the plate are formed, and a conductive material is filled in the through holes to form through electrodes.

[0003] When forming through holes in a glass plate, as an example, the method disclosed in Patent Document 1 is adopted. In this method, first, a laser is irradiated onto a planned formation portion of a through hole in the glass plate to modify the planned formation portion. Since the modified portion has a property of being easily etched, the etching rate becomes higher than that of the unmodified portion. Then, by etching the glass plate, through holes are formed in the planned formation portion.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] A glass plate in which through holes are formed by the above method may have minute irregularities on the inner peripheral surface of the through holes. At this time, if regions with large irregularities and regions with small irregularities are mixed on the inner peripheral surface, when through electrodes are formed in the through holes, regions with low signal transmission characteristics and regions with high signal transmission characteristics will be mixed. Due to this variation in transmission characteristics, there was a risk of problems such as signal waveform distortion.

[0006] In light of the circumstances described above, the challenge to be addressed is to create a glass plate in which the depth of the recesses or the height of the protrusions on the inner surface of the through-hole are uniform. [Means for solving the problem]

[0007] The first glass plate for solving the above problems is a glass plate having a through hole formed from the front surface to the back surface, wherein the inner circumferential surface of the through hole is uneven, the shape of the opening on the surface of the through hole is elliptical, and when the parallel roughness RPL of the major axis end region and the parallel roughness RPS of the minor axis end region are defined according to (A) to (E) below, the ratio (RPL / RPS) is 0.2 or more and 2.0 or less. (A) Of the inner surface of the through hole, the region located at the intersection with the major axis of the ellipse is defined as the major axis end region, and the region located at the intersection with the minor axis is defined as the minor axis end region. (B) The major axis end region is defined as a region with an elliptical shape, with the major axis at the center of the width and a width of 10 μm in the direction of the minor axis, and a depth of 100 μm in the direction of the plate thickness from the surface. (C) The minor axis end region is defined as a region with an elliptical shape, with the minor axis at the center of the width, having a width of 10 μm in the direction of the major axis, and a depth of 100 μm in the direction of the plate thickness from the surface. (D) Sixty-one lines parallel to the surface are set on the long axis end region, and the arithmetic mean roughness is calculated along each of the sixty-one lines. The average of these sixty-one arithmetic mean roughness values ​​is defined as the long axis end region parallel roughness RPL. (E) Sixty-one lines parallel to the surface are set on the short-axis end region, and the arithmetic mean roughness is calculated along each of the sixty-one lines. The average of these sixty-one arithmetic mean roughness values ​​is defined as the short-axis end region parallel roughness RPS.

[0008] In the first glass plate, as the ratio (RPL / RPS) value falls within the above numerical range, the difference in the size of the irregularities between the area around the intersection with the major axis and the area around the intersection with the minor axis on the inner surface of the through hole is small (the closer the ratio value is to 1, the smaller the difference in the size of the irregularities). In other words, in the first glass plate, the mixing of areas with large and small irregularities on the inner surface of the through hole is prevented as much as possible. The irregularities referred to here are those that can be traced along the inner surface of the through hole in a direction parallel to the surface of the glass plate. As a result, it becomes possible to realize a glass plate in which the depth of the recesses or the height of the protrusions on the inner surface of the through hole are uniform.

[0009] The second glass plate is a configuration of the first glass plate described above in which the parallel roughness RPL in the long axis region and the parallel roughness RPS in the short axis region are 200 nm or less.

[0010] In the second glass plate, both RPL and RPS are small, less than 200 nm, and the irregularities in both the region around the intersection with the long axis and the region around the intersection with the short axis on the inner surface of the through hole are small. Therefore, when a through electrode is formed in the through hole, the signal transmission characteristics can be improved.

[0011] The third glass plate is a glass plate of the first or second type described above, in which, when the vertical roughness RVL of the long axis region and the vertical roughness RVS of the short axis region are defined according to (F) and (G) below, the ratio (RVL / RVS) is between 0.2 and 2.0. (F) Sixty-one lines extending along the thickness direction are set on the long axis end region, and the arithmetic mean roughness is calculated along each of the sixty-one lines. The average of these sixty-one arithmetic mean roughness values ​​is defined as the long axis end region perpendicular roughness RVL. (G) Sixty-one lines extending along the thickness direction are set on the short-axis end region, and the arithmetic mean roughness is calculated along each of the sixty-one lines. The average of these sixty-one arithmetic mean roughness values ​​is defined as the short-axis end region perpendicular roughness RVS.

[0012] In the third glass plate, as the ratio (RVL / RVS) value falls within the above numerical range, the difference in the magnitude of the irregularities between the area around the intersection with the major axis and the area around the intersection with the minor axis on the inner surface of the through hole is small. Here, irregularities refer to the irregularities when the inner surface of the through hole is traced along the thickness direction of the glass plate. This makes it possible to realize a glass plate in which the depth of the recesses or the height of the protrusions on the inner surface of the through hole are even more uniform.

[0013] The fourth glass plate is a configuration of the third glass plate described above in which the vertical roughness RVL in the long-axis region and the vertical roughness RVS in the short-axis region are 200 nm or less.

[0014] In the fourth glass plate, both RVL and RVS are small, less than 200 nm, which further improves the signal transmission characteristics when through-hole electrodes are formed in the through-holes.

[0015] The fifth glass plate is one of the first to fourth glass plates described above, wherein the through hole has a constricted portion midway from the front surface to the back surface, and the opening area at the constricted portion is smaller than the opening areas at the front and back surfaces.

[0016] In the fifth glass plate, the through-hole has a constricted portion, which prevents the through-electrode from detaching from the through-hole when it is formed in the through-hole.

[0017] The sixth glass plate is one of the first to fifth glass plates described above, wherein the inner surface of the through hole is an etched surface.

[0018] In the sixth glass plate, since the inner surface of the through-hole is an etched surface, microcracks are not formed on the inner surface of the through-hole, making it possible to form a through-hole with high strength.

[0019] The seventh glass plate for solving the above problems is a glass plate in which a through hole penetrating from the front surface to the back surface is formed, the inner peripheral surface of the through hole has irregularities, the shape of the opening on the front surface of the through hole is an elliptical shape, and when the major axis end region perpendicular roughness RVL and the minor axis end region perpendicular roughness RVS are defined by the following (A) to (C), (F), and (G), the value of the ratio (RVL / RVS) is 0.2 or more and 2.0 or less. (A) Among the inner peripheral surfaces of the through hole, the region located at the intersection with the major axis of the elliptical shape is defined as the major axis end region, and the region located at the intersection with the minor axis is defined as the minor axis end region. (B) The major axis end region is a region having a width of 10 μm in the minor axis direction with the major axis of the elliptical shape as the center of the width and a depth of 100 μm in the plate thickness direction from the front surface. (C) The minor axis end region is a region having a width of 10 μm in the major axis direction with the minor axis of the elliptical shape as the center of the width and a depth of 100 μm in the plate thickness direction from the front surface. (F) After setting 61 lines extending along the plate thickness direction on the major axis end region, the arithmetic mean roughness is calculated along each of the 61 lines, and the average value of the 61 arithmetic mean roughness values is defined as the major axis end region perpendicular roughness RVL. (G) After setting 61 lines extending along the plate thickness direction on the minor axis end region, the arithmetic mean roughness is calculated along each of the 61 lines, and the average value of the 61 arithmetic mean roughness values is defined as the minor axis end region perpendicular roughness RVS.

[0020] In the seventh glass plate, it is possible to obtain the same effects as those of the first glass plate and the third glass plate described above.

Advantages of the Invention

[0021] According to the glass plate of the present disclosure, the depth of the concave portion or the height of the convex portion on the inner peripheral surface of the through hole can be made uniform.

Brief Description of the Drawings

[0022] [Figure 1] (a) is a plan view of the glass plate, (b) is a cross-sectional view showing the B-B cross section of (a), and (c) is a cross-sectional view showing the C-C cross section of (a). [Figure 2] This is a plan view showing the procedure for cutting a glass plate, which is one of the steps for determining the parallel roughness (RPL) of the long axis region. [Figure 3] (a) is an image taken with a laser microscope of the area including the through-hole in the glass plate, and (b) is a height image obtained by cropping the area within the white frame shown in (a) and removing the effects of curvature and undulation on the inner surface of the through-hole. [Figure 4] This is a plan view showing the procedure for cutting a glass plate, which is one of the steps for determining the parallel roughness RPS (Rapid Scale Proportion) in the short-axis region. [Figure 5] (a) is an image taken with a laser microscope of the area including the through-hole in the glass plate, and (b) is a height image obtained by cropping the area within the white frame shown in (a) and removing the effects of curvature and undulation on the inner surface of the through-hole. [Figure 6] This figure shows the laser irradiation process in the manufacturing method of glass plates. [Modes for carrying out the invention]

[0023] The following describes an embodiment of the glass plate with reference to the attached drawings.

[0024] <glass plate> Figures 1(a) to (c) show the glass plate 1. The glass plate 1 can be made of soda glass, quartz glass, alkali-free glass, borosilicate glass, aluminosilicate glass, crystallized glass, etc. When the glass plate 1 is used as a substrate for electronic equipment, it is preferably made of quartz glass, alkali-free glass, borosilicate glass, or alkali aluminosilicate glass.

[0025] Here, "alkali-free glass" refers to glass that is substantially free of alkali components (alkali metal oxides), and specifically, glass in which the weight ratio of alkali components in the glass composition is 3000 ppm or less. The weight ratio of alkali components in the glass composition of glass plate 1 is preferably 1000 ppm or less, more preferably 500 ppm or less, and most preferably 300 ppm or less.

[0026] When glass plate 1 is made of alkali-free glass, it is preferable that the glass composition contains, for example, SiO2 60-75%, Al2O 35-20%, B2O 30-15%, Li2O+Na2O+K2O (total amount of Li2O, Na2O, and K2O) 0-1%, MgO 0-10%, CaO 0-15%, SrO 0-10%, and BaO 0-10% in mole percent.

[0027] When glass plate 1 is made of borosilicate glass, it is preferable that the glass composition contains, for example, SiO2 70-85%, Al2O 30-10%, B2O 35-20%, Li2O 0-5%, Na2O 0-10%, K2O 0-5%, MgO 0-5%, CaO 0-5%, SrO 0-5%, and BaO 0-5% in molar percentages.

[0028] When glass plate 1 is made of alkali aluminosilicate glass, it is preferable that the glass composition contains, for example, SiO2 50-80%, Al2O3 8-25%, B2O3 0-10%, Li2O 1-15%, Na2O 3-21%, K2O 0-10%, MgO 0-10%, CaO 0-5%, SrO 0-5%, BaO 0-5%, P2O 50-15%, and ZnO 0-5% in mole percent.

[0029] The glass plate 1 is preferably rectangular in shape, and its length and width dimensions are, for example, 10 mm x 10 mm or more and 700 mm x 700 mm or less. The thickness of the glass plate 1 is preferably 0.03 mm or more and 10 mm or less. The lower limit of the thickness of the glass plate 1 is preferably 0.05 mm or more, 0.1 mm or more, 0.2 mm or more, and 0.3 mm or more. The upper limit of the thickness of the glass plate 1 is preferably 5 mm or less, 3 mm or less, 2 mm or less, and 1.5 mm or less.

[0030] The glass plate 1 has multiple through holes 4 that penetrate from the front surface 2 to the back surface 3. Here, "front surface 2" refers to the surface onto which the laser 6, described later, is incident when irradiating the original glass plate 5 (see Figure 6) to form the through holes 4. On the other hand, "back surface 3" refers to the surface on the back side of the front surface 2. The multiple through holes 4 are formed under the same conditions and can be considered to be substantially the same shape.

[0031] For each of the multiple through holes 4, the shape of the opening on the surface 2 of the glass plate 1 is elliptical. Note that in Figure 1(a), the ellipticity (ratio of major axis to minor axis) of the elliptical shape of the through holes 4 is exaggerated, and in reality the roundness is higher than the elliptical shape shown. The major axis (length of the major axis 7) of the ellipse is, for example, between 10 μm and 200 μm. On the other hand, the minor axis (length of the minor axis 8) of the ellipse is, for example, between 10 μm and 200 μm.

[0032] Here, the elliptical shape of the through-hole 4 is preferably as round as possible, and the difference between the major axis and the minor axis is preferably 10 μm or less, more preferably 7 μm or less, even more preferably 5 μm or less, and even more preferably 3 μm or less.

[0033] The through-hole 4 has an opening area (hole cross-sectional area) that gradually changes along the thickness direction of the glass plate, and the through-hole 4 has a constricted portion 9 midway from the surface 2 to the back surface 3 of the glass plate 1. In this embodiment, the constricted portion 9 is formed approximately in the center of the thickness of the glass plate 1. The opening area at the constricted portion 9 is smaller than the opening areas at the surface 2 and back surface 3. As a result, in the through-hole 4, the surface 2 side and the back surface 3 side, with the constricted portion 9 as the boundary, are formed in a tapered shape in opposite directions.

[0034] The inner surface 10 of the through hole 4 is curved in an elliptical arc shape. Numerous minute irregularities (not shown) are formed on the inner surface 10 of the through hole 4. The inner surface 10 of the through hole 4 is an etched surface formed by etching the glass plate 5 (the original glass plate of glass plate 1) with the etching solution described later.

[0035] In this glass plate 1, when the parallel roughness RPL in the long axis end region and the parallel roughness RPS in the short axis end region are defined for the through hole 4 according to (A) to (E) below, the ratio (RPL / RPS) is between 0.2 and 2.0. A ratio (RPL / RPS) close to 1 indicates that the difference in the size of the irregularities (irregularities when the inner surface 10 is traced along a direction parallel to the surface 2 of the glass plate 1) between the area around the intersection with the long axis 7 and the area around the intersection with the short axis 8 on the inner circumferential surface 10 of the through hole 4 is small.

[0036] Here, the value of the ratio (RPL / RPS) is more preferably 0.5 or greater, even more preferably 0.8 or greater, and most preferably 0.9 or greater. Furthermore, the value of the ratio (RPL / RPS) is more preferably 1.5 or less, even more preferably 1.2 or less, and most preferably 1.1 or less.

[0037] Furthermore, in this glass plate 1, both the parallel roughness RPL in the long axis region and the parallel roughness RPS in the short axis region are 200 nm or less. The small RPL and RPS indicate that the irregularities present in both the area around the intersection with the long axis 7 and the area around the intersection with the short axis 8 on the inner circumferential surface 10 of the through hole 4 are small.

[0038] Here, the parallel roughness RPL in the long axis end region and the parallel roughness RPS in the short axis end region are more preferably 100 nm or less, even more preferably 50 nm or less, and most preferably 20 nm or less.

[0039] [Explanation of (A)] (A) Of the inner circumferential surface 10 of the through hole 4, the region located at the intersection with the major axis 7 of the ellipse is defined as the major axis end region 11, and the region located at the intersection with the minor axis 8 is defined as the minor axis end region 12.

[0040] There are two major axis end regions 11 and two minor axis end regions 12 for each through hole 4. In the following description, when distinguishing between the two major axis end regions 11, one will be called the first major axis end region 11a and the other the second major axis end region 11b. Similarly, when distinguishing between the two minor axis end regions 12, one will be called the first minor axis end region 12a and the other the second minor axis end region 12b. In this embodiment, when the surface 2 of the glass plate 1 is viewed from above, the two major axis end regions 11 and the two minor axis end regions 12 are arranged clockwise in the order of the first major axis end region 11a, the first minor axis end region 12a, the second major axis end region 11b, and the second minor axis end region 12b.

[0041] [Explanation of (B)] (B) The major axis end region 11 is defined as a region with an elliptical shape, where the major axis 7 is the center of the width W1, and a width W1 of 10 μm in the direction of the minor axis (the direction in which the minor axis 8 extends), and a depth D1 of 100 μm in the plate thickness direction from the surface 2.

[0042] Here, the width W1 of the long axis end region 11 is the dimension along the short axis direction when the long axis end region 11 is projected onto the BB cross section in Figure 1. In other words, the width W1 of the long axis end region 11 is the dimension along the short axis direction when the long axis end region 11 is viewed from a direction parallel to the long axis 7. Also, the depth D1 of the long axis end region 11 is the dimension along the plate thickness direction when the long axis end region 11 is projected onto the BB cross section in Figure 1. In other words, the depth D1 of the long axis end region 11 is the dimension along the plate thickness direction when the long axis end region 11 is viewed from a direction parallel to the long axis 7.

[0043] [Explanation of (C)] (C) The minor axis end region 12 is defined as a region with an elliptical shape, where the minor axis 8 is the center of the width W2, and a width W2 of 10 μm in the direction of the major axis (the direction in which the major axis 7 extends), and a depth D2 of 100 μm in the plate thickness direction from the surface 2.

[0044] Here, the width W2 of the minor axis end region 12 is the dimension along the major axis direction when the minor axis end region 12 is projected onto the CC cross section in Figure 1. In other words, the width W2 of the minor axis end region 12 is the dimension along the major axis direction when the minor axis end region 12 is viewed from a direction parallel to the minor axis 8. Also, the depth D2 of the minor axis end region 12 is the dimension along the plate thickness direction when the minor axis end region 12 is projected onto the CC cross section in Figure 1. In other words, the depth D2 of the minor axis end region 12 is the dimension along the plate thickness direction when the minor axis end region 12 is viewed from a direction parallel to the minor axis 8.

[0045] [Explanation of (D)] (D) Sixty-one lines (not shown) parallel to the surface 2 are set on the long axis end region 11, and the arithmetic mean roughness is calculated along each of the sixty-one lines. The average of the sixty-one arithmetic mean roughness values ​​is defined as the long axis end region parallel roughness RPL.

[0046] The procedure for determining the parallel roughness RPL (Rapid Parallelism) of the long axis end region will be explained below with reference to Figures 2 and 3.

[0047] First, as shown in Figure 2, the glass plate 1 (shown in magnified view, only around the through-hole 4) is cut along a line 13 that coincides with the minor axis 8 of the elliptical shape of the through-hole 4. Specifically, a scribe line is formed on the glass plate 1 along line 13, and then the glass plate 1 is cut along the scribe line. In this embodiment, the cut surface 14 of the glass plate 1 formed by the cutting is not subjected to polishing or other processing, but polishing or other processing may be performed on the cut surface 14.

[0048] Next, for each of the cut glass plates 1, the area including the through-hole 4 is imaged using a laser microscope from a direction perpendicular to the cut surface 14 (indicated by the white arrow A1 in Figure 2). A Keyence VK-X250 laser microscope is used. This yields an image like the one shown in Figure 3(a) as an example.

[0049] Next, from the image in Figure 3(a), the area enclosed by the rectangular white frame, corresponding to the long axis end region 11, is cropped. Hereafter, the cropped image will be referred to as the cropped image. The cropping was performed using the analysis application (version 3.8.0.0) included with the laser microscope. In the cropped image, in addition to the effect of minute irregularities on the inner surface 10 of the through hole 4, the effects of curvature and undulation on the inner surface 10 are reflected as brightness and darkness in the image. Specifically, the bright areas in the cropped image are protruding, and the dark areas are conversely recessed.

[0050] Next, 61 lines (not shown) extending in the X direction are set on the trimmed image (long axis end region 11) as 61 lines parallel to the surface 2 of the glass plate 1. The 61 lines are set to be evenly spaced in the Z direction. Each of the 61 lines contains the effects of the minute irregularities, curvature, and undulations mentioned above. Therefore, the following [Process 1] to [Process 3] are performed with the aim of extracting only the effects of substantially minute irregularities from each of the 61 lines.

[0051] In [Process 1], the effect of curvature on the inner circumferential surface 10 of the through hole 4 is removed from each of the 61 lines. Specifically, the quadratic surface correction function of the laser microscope is used to remove the effect of elliptical arc curvature in the major axis end region 11 (see also the elliptical arc shown as a thick line in Figure 1) from each of the 61 lines.

[0052] In [Process 2], the effect of waviness on the inner surface 10 of the through hole 4 is removed from each of the 61 lines. Specifically, the multi-file analysis application (version 1.3.1.1) attached to the laser microscope is used, and the waviness removal function of the application is used. The value of the waviness removal parameter is set to 10.

[0053] In [Process 3], a laser microscope cutoff filter is used, with a low-pass filter of 0.8 μm and a high-pass filter of 0.25 mm (when calculating vertical roughness) or 0.025 mm (when calculating parallel roughness). The low-pass filter removes unnecessary interference elements (noise) when calculating the arithmetic mean roughness along each of the 61 lines. The high-pass filter is used to correct the slope for each line.

[0054] Through the processes of [Process 1] to [Process 3], an image like the one shown in Figure 3(b) is obtained as an example. In this image, the effects of curvature and undulation on the inner surface 10 of the through hole 4 are removed, and only the effects of minute irregularities present on the inner surface 10 are reflected as brightness and darkness in the image.

[0055] Finally, the arithmetic mean roughness is calculated for each of the 61 lines after going through [Process 1] to [Process 3], and the average of the 61 arithmetic mean roughness values ​​is taken as the major axis end region parallel roughness RPL.

[0056] [Explanation of (E)] (E) Sixty-one lines parallel to the surface 2 are set on the short-axis end region 12, and the arithmetic mean roughness is calculated along each of the sixty-one lines. The average of the sixty-one arithmetic mean roughness values ​​is defined as the short-axis end region parallel roughness RPS.

[0057] The procedure for determining the parallel roughness RPS in the short-axis region will be explained below with reference to Figures 4 and 5. Since this procedure shares many similarities with the procedure for determining the parallel roughness RPL in the long-axis region described above, we will mainly explain the differences.

[0058] First, as shown in Figure 4, the glass plate 1 (shown in magnified view, only the area around the through-hole 4) is cut along the line 15 that overlaps with the major axis 7 of the elliptical shape of the through-hole 4. Note that the through-hole 4 shown in Figure 4 is a different hole from the through-hole 4 shown in Figure 2.

[0059] Next, for each of the cut glass plates 1, the area including the through-hole 4 is imaged using a laser microscope from a direction perpendicular to the cut surface 16 (the direction indicated by the white arrow A2 in Figure 4). This yields an image like the one shown in Figure 5(a) as an example.

[0060] Next, from the image in Figure 5(a), the area enclosed by the rectangular white frame is cropped to represent the range corresponding to the short-axis end region 12.

[0061] Next, 61 lines (not shown) extending in the Y direction on the trimmed image (short axis end region 12) are set as 61 lines parallel to the surface 2 of the glass plate 1. Then, for each of the 61 lines, [Process 1'] to [Process 3'] are performed with the aim of extracting only the effect of substantially minute irregularities.

[0062] In [Process 1'], the quadratic surface correction function of the laser microscope is used to remove the effect of the elliptical arc curvature in the minor axis end region 12 (see also the elliptical arc shown as a thick line in Figure 1) from each of the 61 lines.

[0063] In [Process 2'] and [Process 3'], the same processes as those performed in [Process 2] and [Process 3] above to determine the parallel roughness RPL of the long axis end region are carried out. Through the process of [Process 1'] to [Process 3'], an image like the one shown in Figure 5(b) is obtained as an example.

[0064] Finally, the arithmetic mean roughness is calculated for each of the 61 lines after going through [Process 1'] to [Process 3'], and the average of the 61 arithmetic mean roughness values ​​is taken as the short-axis end region parallel roughness RPS.

[0065] In this glass plate 1, when the vertical roughness RVL in the long axis end region and the vertical roughness RVS in the short axis end region are defined for the through hole 4 according to (F) and (G) below, the ratio (RVL / RVS) is between 0.2 and 2.0. A ratio (RVL / RVS) close to 1 indicates that the difference in the size of the irregularities (irregularities when tracing the inner surface 10 along the thickness direction of the glass plate 1) between the area around the intersection with the long axis 7 and the area around the intersection with the short axis 8 on the inner circumferential surface 10 of the through hole 4 is small.

[0066] Here, the value of the ratio (RVL / RVS) is more preferably 0.5 or greater, even more preferably 0.8 or greater, and most preferably 0.9 or greater. Furthermore, the value of the ratio (RVL / RVS) is more preferably 1.5 or less, even more preferably 1.2 or less, and most preferably 1.1 or less.

[0067] Furthermore, in this glass plate 1, both the longitudinal roughness RVL in the long axis region and the longitudinal roughness RVS in the short axis region are 200 nm or less. Small RVL and RVS indicate that the irregularities present in both the area around the intersection with the long axis 7 and the area around the intersection with the short axis 8 on the inner circumferential surface 10 of the through hole 4 are small.

[0068] Here, the longitudinal end region vertical roughness RVL and the longitudinal end region vertical roughness RVS are more preferably 150 nm or less, even more preferably 100 nm or less, and most preferably 80 nm or less.

[0069] [Explanation of (F)] (F) Sixty-one lines extending in the thickness direction are set on the long axis end region 11, and the arithmetic mean roughness is calculated along each of the sixty-one lines. The average of the sixty-one arithmetic mean roughness values ​​is defined as the long axis end region perpendicular roughness RVL.

[0070] Here, the procedure for determining the vertical roughness RVL of the long axis end region is almost the same as the procedure for determining the parallel roughness RPL of the long axis end region described above, the only difference being that 61 lines extending in the Z direction are set on the trimmed image (long axis end region 11) within the white frame in Figure 3(a), instead of 61 lines extending in the X direction. For this reason, the explanation of the procedure for determining the vertical roughness RVL of the long axis end region will be omitted.

[0071] [Explanation of (G)] (G) Sixty-one lines extending along the thickness direction are set on the short-axis end region 12, and the arithmetic mean roughness is calculated along each of the sixty-one lines. The average of the sixty-one arithmetic mean roughness values ​​is taken as the short-axis end region perpendicular roughness RVS.

[0072] Here, the procedure for determining the vertical roughness RVS of the short axis end region is almost the same as the procedure for determining the parallel roughness RPS of the short axis end region described above, the only difference being that 61 lines extending in the Z direction are set on the trimmed image (short axis end region 12) within the white frame in Figure 5(a), instead of 61 lines extending in the Y direction. For this reason, the explanation of the procedure for determining the vertical roughness RVS of the short axis end region will be omitted.

[0073] The manufacturing method for the glass plate 1 described above will be explained below.

[0074] <Method for manufacturing glass plates> This manufacturing method comprises a laser irradiation step P (Figure 6) and an etching step (not shown). The laser irradiation step P is a step in which a laser 6 is irradiated onto the glass plate 5 that will become the base glass plate 1 to form a modified portion 17 on the glass plate 5. The etching step is a step in which the glass plate 5 is etched after the laser irradiation step P has been performed.

[0075] [Laser irradiation process] In the laser irradiation process P, as shown in Figure 6, the glass plate 5 is placed flat with surface 2 facing upwards. The glass plate 5 can be placed on, for example, a surface plate (not shown). An irradiation device 18 is used to irradiate the glass plate 5 with the laser 6. The irradiation device 18 is positioned above the glass plate 5. The irradiation device 18 can be moved three-dimensionally by a drive device (not shown).

[0076] The irradiation device 18 is preferably a device that irradiates with a pulsed laser as the laser 6. With a pulsed laser, the glass plate 5 can be heated efficiently by increasing the energy per pulse. Furthermore, by shortening the pulse duration, it is possible to prevent the glass plate 5 from being damaged due to heat diffusion.

[0077] The laser 6 is preferably a picosecond laser or a femtosecond laser, and its pulse width is preferably, for example, 50 fs to 100 ps. The energy per pulse of the laser 6 is preferably 35 μJ to 80 μJ. The lower limit of the energy per pulse of the laser 6 is preferably 40 μJ or more, 45 μJ or more, 50 μJ or more, or 55 μJ or more. The upper limit of the energy per pulse of the laser 6 is preferably 75 μJ or less, 70 μJ or less, 65 μJ or less, or 60 μJ or less.

[0078] The wavelength of the laser 6 is preferably between 400 nm and 1050 nm. In the same wavelength range, the linear transmittance of the glass plate 5 is preferably 80% or higher. If the wavelength of the laser 6 is within the above wavelength range, the area in which the modified portion 17 is formed by multiphoton absorption can be reduced. This makes it possible to remove the modified portion 17 in the subsequent etching process and improve the roundness of the holes when through holes 4 are formed in the glass plate 5.

[0079] On the other hand, if the wavelength of the laser 6 is not within the above wavelength range, the absorption coefficient of the laser 6 with respect to the glass plate 5 increases, and the proportion of the laser 6 absorbed by the surface 2 increases. As a result, it becomes difficult to sufficiently heat the inside and back surface 3 of the glass plate 5. Consequently, when forming through holes 4 in the glass plate 5 in the subsequent etching process, a situation may arise where the hole diameter differs significantly between the surface 2 side and the back surface 3 side. In addition, the temperature of the area irradiated with the laser becomes too high, causing excessive stress in the glass plate 5, making it more prone to cracks and other damage when forming the through holes 4.

[0080] The irradiation device 18 preferably shapes the laser 6 into a Bessel beam using an optical system including an axicon lens. This allows the modified portion 17 to be formed over the entire thickness of the glass plate 5 with just one laser pulse, thus reducing the time required to form the modified portion 17. In this embodiment, the focal length of the laser 6 is, for example, 0.1 mm to 10 mm. The spot diameter of the laser 6 is, for example, 0.1 μm to 10 μm.

[0081] When the laser 6 is irradiated onto the glass plate 5 from the irradiation device 18, a modified area 17 is formed on the glass plate 5. In the modified area 17, at least one of the properties among stress, density, and optical properties has changed, or minute cracks or voids have been formed. On the other hand, in the unmodified area (the part excluding the modified area 17), at least one of the properties among stress, density, and optical properties has not changed, or only a substantially negligible change has occurred. Furthermore, no minute cracks or voids have been formed in the unmodified area. Since the etching rate is higher in the modified area 17 than in the unmodified area, in the subsequent etching process, the modified area 17 is preferentially removed from the glass plate 5 over the unmodified area.

[0082] By moving the irradiation position of the laser 6 onto the glass plate 5 and repeatedly irradiating it with the laser 6, multiple modified areas 17 are formed on the glass plate 5. In this embodiment, each time the irradiation device 18 irradiates with one pulse of the laser 6, the irradiation position of the laser 6 onto the glass plate 5 is moved. In other words, each of the multiple modified areas 17 is formed by a single pulse of the laser 6.

[0083] [Etching process] In the etching process, the glass plate 5, on which multiple modified sections 17 have been formed, is etched with an etching solution to form multiple through-holes 4 in the glass plate 5. This produces a glass plate 1 from the glass plate 5. Here, for example, an aqueous HF solution, an aqueous NaOH solution, or an aqueous KOH solution can be used as the etching solution, but it is preferable to use an aqueous HF solution because it can shorten the time required to form the through-holes 4. In addition, HCl, H2SO4, or HNO3 may be added as additives to the aqueous HF solution. Furthermore, a surfactant may also be added.

[0084] The following are specific examples of glass plate 1.

[0085] As a specific example, glass plate 1 was manufactured from glass plate 5 under the following conditions. Subsequently, the values ​​of the parallel roughness RPL in the long axis region, the parallel roughness RPS in the short axis region, the ratio (RPL / RPS), the perpendicular roughness RVL in the long axis region, the perpendicular roughness RVS in the short axis region, and the ratio (RVL / RVS) were calculated.

[0086] First, a glass plate 5 was prepared as the base for glass plate 1, with a composition of SiO2 66.2%, Al2O3 12.8%, B2O 36.4%, MgO 4.2%, CaO 7.6%, SrO 0.3%, and BaO 2.5% in molar percentages. Glass plate 5 is rectangular with dimensions of 35 mm x 20 mm and a thickness of 0.5 mm.

[0087] Next, a laser 6 was irradiated onto the glass plate 5 from the surface 2 side, forming a total of 800 modified areas 17 arranged in an 8x100 grid on the lengthwise and widthwise sides of the glass plate 5. The distance between adjacent modified areas 17 was 150 μm. The laser 6 was a pulsed laser with a wavelength of 515 nm and a pulse width of 0.2 to 50 ps, ​​and was operated in single-pulse mode without using burst pulses. The output power of the laser 6 was set to 0.6 W. The laser beam was formed into a Bessel beam using an optical system including an axicon lens. The focal length of the Bessel beam was approximately 1 mm, which is longer than the thickness of the glass plate 5. The laser was irradiated with the center of the Bessel beam's focal point roughly aligned with the center of the glass plate 5's thickness, and modified areas 17 were formed across the entire thickness of the glass plate 5 with just one laser pulse.

[0088] Finally, the glass plate 5, on which 800 modified sections 17 were formed, was etched by immersion in an etching solution. The etching solution used was an aqueous solution of mixed acid consisting of 2.5 mol / L HF and 1.0 mol / L HCl. The temperature of the etching solution was maintained at 30°C using a chiller. In this manner, glass plate 1 was manufactured from glass plate 5.

[0089] From the glass plate 1 manufactured under the above conditions, one through-hole 4 was randomly selected from 800 through-holes 4 to be used for calculating the RPL and RVL. The selected through-hole 4 contained two major axis end regions 11, and these two major axis end regions 11 were designated as sample No. 1 and sample No. 2, respectively. No. 1 is the first major axis end region 11a, and No. 2 is the second major axis end region 11b. For each of these samples, sample No. 1 and sample No. 2, the parallel roughness RPL and the perpendicular roughness RVL of the major axis end region were determined, respectively.

[0090] In addition, separate from the single through-hole 4 described above, one through-hole 4 was randomly selected from among 800 through-holes 4 to be used for calculating the RPS and RVS described above. The selected through-hole 4 contained two short-axis end regions 12, and these two short-axis end regions 12 were designated as sample No. 3 and sample No. 4, respectively. No. 3 is the first short-axis end region 12a, and No. 4 is the second short-axis end region 12b. For each of these samples, sample No. 3 and sample No. 4, the short-axis end region parallel roughness RPS and the short-axis end region perpendicular roughness RVS were calculated, respectively.

[0091] Table 1 shows the results of determining the parallel roughness RPL (long axis end region) for sample No. 1 and sample No. 2, and the results of determining the parallel roughness RPS (short axis end region) for sample No. 3 and sample No. 4.

[0092] [Table 1]

[0093] In Table 1, "Average" refers to the average value of the 61 arithmetic mean roughness values ​​that form the basis of RPL and RPS. In other words, the "Average" value is the RPL and RPS for each sample. "Maximum" refers to the maximum value of the 61 arithmetic mean roughness values ​​that form the basis of RPL and RPS. On the other hand, "Minimum" refers to the minimum value of the 61 arithmetic mean roughness values ​​that form the basis of RPL and RPS. "Standard Deviation" refers to the standard deviation of the 61 arithmetic mean roughness values ​​that form the basis of RPL and RPS.

[0094] Table 2 shows the ratio (RPL / RPS) values ​​for the "sample combinations" listed in the table.

[0095] [Table 2]

[0096] As shown in [Table 2], the ratio (RPL / RPS) value is between 0.2 and 2.0, indicating that in this glass plate 1, the difference in the size of irregularities between the area around the intersection with the long axis 7 and the area around the intersection with the short axis 8 on the inner surface 10 of the through hole 4 is small. This suggests that when through electrodes are formed in the through hole 4, variations in signal transmission characteristics can be prevented.

[0097] Table 3 shows the results of determining the vertical roughness RVL in the long-axis region of sample No. 1 and sample No. 2, and the results of determining the vertical roughness RVS in the short-axis region of sample No. 3 and sample No. 4.

[0098] [Table 3]

[0099] In Table 3, "Average" refers to the average value of the 61 arithmetic mean roughness values ​​that form the basis of RVL and RVS. In other words, the "Average" value is the RVL and RVS for each sample. "Maximum" refers to the maximum value of the 61 arithmetic mean roughness values ​​that form the basis of RVL and RVS. On the other hand, "Minimum" refers to the minimum value of the 61 arithmetic mean roughness values ​​that form the basis of RVL and RVS. "Standard Deviation" refers to the standard deviation of the 61 arithmetic mean roughness values ​​that form the basis of RVL and RVS.

[0100] Table 4 shows the ratio (RVL / RVS) values ​​for the "sample combinations" listed in the table.

[0101] [Table 4]

[0102] As shown in [Table 4], the ratio (RVL / RVS) value is between 0.2 and 2.0, indicating that in this glass plate 1, the difference in the size of irregularities between the area around the intersection with the long axis 7 and the area around the intersection with the short axis 8 on the inner circumferential surface 10 of the through hole 4 is small. This suggests that when through electrodes are formed in the through hole 4, variations in signal transmission characteristics can be prevented.

[0103] If the laser irradiation conditions and etching conditions are the same across multiple through-holes 4, the surface condition of the inner circumferential surface of the through-holes 4 will also be the same. Therefore, in the above example, samples No. 1 and No. 2 were obtained by processing one through-hole 4, but it is also possible to process two through-holes 4 to obtain sample No. 1 from one through-hole 4 and sample No. 2 from the other through-hole 4. Similarly, in the above example, samples No. 3 and No. 4 were obtained by processing one through-hole 4, but it is also possible to process two through-holes 4 to obtain sample No. 3 from one through-hole 4 and sample No. 4 from the other through-hole 4. [Explanation of Symbols]

[0104] 1 glass plate 2 surface 3 Back side 4 through holes 7 Long axis 8 Short axis 9. Waist area 10 Inner surface 11 Long axis end area 12 Short axis end area D1 Depth D2 Depth W1 width W2 width

Claims

1. A glass plate having a through hole formed that penetrates from the front surface to the back surface, The inner circumferential surface of the through hole has irregularities, The shape of the opening on the surface in the through hole is elliptical. A glass plate characterized in that, when the parallel roughness RPL of the long axis end region and the parallel roughness RPS of the short axis end region are defined according to (A) to (E) below, the ratio (RPL / RPS) is 0.2 or more and 2.0 or less. (A) Of the inner circumferential surface of the through hole, the region located at the intersection with the major axis of the ellipse is defined as the major axis end region, and the region located at the intersection with the minor axis is defined as the minor axis end region. (B) The major axis end region is defined as a region having a width of 10 μm in the direction of the minor axis with the major axis of the ellipse as the center of the width, and a depth of 100 μm in the direction of the plate thickness from the surface. (C) The minor axis end region is defined as a region having a width of 10 μm in the direction of the major axis with the minor axis of the ellipse as the center of the width, and a depth of 100 μm in the direction of the plate thickness from the surface. (D) Sixty-one lines parallel to the surface are set on the long axis end region, and the arithmetic mean roughness is calculated along each of the sixty-one lines. The average of the sixty-one arithmetic mean roughness values ​​is defined as the long axis end region parallel roughness RPL. (E) Sixty-one lines parallel to the surface are set on the short-axis end region, and the arithmetic mean roughness is calculated along each of the sixty-one lines. The average of the sixty-one arithmetic mean roughness values ​​is defined as the short-axis end region parallel roughness RPS.

2. The glass plate according to claim 1, characterized in that the parallel roughness RPL of the long axis end region and the parallel roughness RPS of the short axis end region are 200 nm or less.

3. The glass plate according to claim 1, characterized in that when the vertical roughness RVL of the long axis end region and the vertical roughness RVS of the short axis end region are defined by (F) and (G) below, the ratio (RVL / RVS) is 0.2 or more and 2.0 or less. (F) Sixty-one lines extending in the thickness direction are set on the long axis end region, and the arithmetic mean roughness is calculated along each of the sixty-one lines. The average of the sixty-one arithmetic mean roughness values ​​is defined as the vertical roughness RVL of the long axis end region. (G) Sixty-one lines extending in the thickness direction are set on the short-axis end region, and the arithmetic mean roughness is calculated along each of the sixty-one lines. The average of the sixty-one arithmetic mean roughness values ​​is taken as the short-axis end region perpendicular roughness RVS.

4. The glass plate according to claim 3, characterized in that the vertical roughness RVL of the long axis end region and the vertical roughness RVS of the short axis end region are 200 nm or less.

5. The through hole has a constricted portion in the middle from the surface to the back surface, The glass plate according to any one of claims 1 to 4, characterized in that the opening area at the constricted portion is smaller than the opening areas at the surface and the back surface.

6. The glass plate according to any one of claims 1 to 4, characterized in that the inner circumferential surface of the through hole is an etched surface.

7. A glass plate having a through hole formed that penetrates from the front surface to the back surface, The inner circumferential surface of the through hole has irregularities, The shape of the opening on the surface in the through hole is elliptical. A glass plate characterized in that, when the vertical roughness RVL of the long axis end region and the vertical roughness RVS of the short axis end region are defined according to (A) to (C), (F), and (G) below, the ratio (RVL / RVS) is 0.2 or more and 2.0 or less. (A) Of the inner circumferential surface of the through hole, the region located at the intersection with the major axis of the ellipse is defined as the major axis end region, and the region located at the intersection with the minor axis is defined as the minor axis end region. (B) The major axis end region is defined as a region having a width of 10 μm in the direction of the minor axis with the major axis of the ellipse as the center of the width, and a depth of 100 μm in the direction of the plate thickness from the surface. (C) The minor axis end region is defined as a region having a width of 10 μm in the direction of the major axis with the minor axis of the ellipse as the center of the width, and a depth of 100 μm in the direction of the plate thickness from the surface. (F) Sixty-one lines extending in the thickness direction are set on the long axis end region, and the arithmetic mean roughness is calculated along each of the sixty-one lines. The average of the sixty-one arithmetic mean roughness values ​​is defined as the vertical roughness RVL of the long axis end region. (G) Sixty-one lines extending in the thickness direction are set on the short-axis end region, and the arithmetic mean roughness is calculated along each of the sixty-one lines. The average of the sixty-one arithmetic mean roughness values ​​is taken as the short-axis end region perpendicular roughness RVS.

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