KR101920100B1 - Glass substrate cutting method and optical glass for solid-state image capturing device - Google Patents

Abstract

Provided is a cutting method for obtaining a glass substrate having mechanical strength and cleanliness. A laser beam is irradiated to the inside of the glass substrate provided with two light-projecting surfaces opposing in the plate thickness direction, and a laser beam is irradiated along the line along which the glass substrate is to be cut, And a step of cutting the glass substrate along the line along which the object is intended to be cut by causing cracks to be generated in the thickness direction of the glass substrate with the flaw area as a starting point, As a method, the scratch area is separated from at least one of the light-projecting surfaces.

Description

TECHNICAL FIELD [0001] The present invention relates to a glass substrate cutting method, and an optical glass for a solid-state imaging device. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a method of cutting a glass substrate having high mechanical strength and cleanliness, and an optical glass for a solid-state imaging device.

As the digital still camera in which the solid-state image pickup device is used, there is a single-lens reflex type. In this type of camera, dust or dust adhering to the light-projecting surface of an optical glass such as a dust-proof filter is reflected on the sensed image, so that there is often installed a so-called dust removing device that vibrates the optical glass and bounces off the optical glass.

The optical glass is also used as a cover glass for sealing a package containing an image pickup element in a gas-tight manner. The solid-state image pickup device using the image pickup element temporarily fixes the cover glass in its manufacturing process, and then checks the presence or absence of dust attached to the surface of the device based on the output image information from the image pickup device. When it is judged that dust is contained, the temporarily fixed cover glass is removed from the package to clean the imaging element (Patent Document 1).

In the above, since bending stress acts on the glass in any of them, the glass is required to have strength that can withstand it.

In recent years, in response to a request for miniaturization of a digital still camera, an optical glass for such use is often used in a thin plate thickness of about 0.3 to 0.5 mm, and when a strong vibration is applied by a dust removing device, There arises a problem of reliability, such as cracks being generated starting from a minute deficiency of the substrate.

In addition, the solid-state image pickup device using the solid-state image pickup device is progressing in miniaturization, high-resolution image pickup, and high-image area. As the solid-state imaging device and its mounted devices are made thin and large, the optical glass to be used is required to have a large outer shape and the thickness of the optical glass that affects the depth of the solid-state imaging device to be very thin.

Patent Document 2 discloses a cover glass for a solid-state image pickup device which has a coating film on at least one surface of two light-projecting surfaces opposed to each other in the thickness direction of the cover glass, and the outer peripheral surface of the cover glass is cut by a laser, It is described that the coating film is formed before laser cutting. As a result, a cover glass for a solid-state imaging element having high mechanical strength, high optical performance and stable chemical performance and high cleanliness can be obtained.

(Patent Document 1) Japanese Laid-Open Patent Publication No. 2006-303954

(Patent Document 2) Japanese Laid-Open Patent Publication No. 2008-187170

However, the laser cutting method disclosed in Patent Document 2 has the following problems.

In this cutting method, there is a problem that the deviation of the bending strength of the glass becomes large because a cutting depth serving as a cutting starting point of the glass is formed on the glass surface. The reason for this is that when the four-point bending test is performed with the glass surface having the depth of cut formed by the laser downward, the starting point of the crack becomes a certain point of the ridge line cut by the laser. Therefore, if the depth of cutting by the laser is suddenly large or deep, the bending strength of the glass is greatly lowered.

In addition, in this cutting method, since the cutting depth is formed by the laser at both the glass surface and the coating film formed on the surface thereof, protrusions such as roughness caused by the coating film processed by the laser are generated on the cut surface, There is a problem that it is difficult to remove the projections by the cleaning process after the cutting. The glass substrate on which protrusions are generated may fall into the apparatus or adhere to the light-projecting surface due to the protrusions being separated from the glass substrate when attached to the solid-state imaging device.

In addition, when the depth of the inside of the solid-state imaging device is reduced, the distance from the surface of the optical glass to the solid-state imaging element is shortened, so that light incident on the solid- Therefore, when the light incident obliquely on the solid-state image sensing device is reflected on the surface of the solid-state image sensing device, it becomes stray light and is reflected in the solid-state image sensing device, which may adversely affect the sensed image. Usually, an optical multilayer film having an antireflection function is formed on the transparent surface of the optical glass with respect to light in the visible range. However, since the side surface of the optical glass is not provided with a special countermeasure, there is a fear of reflecting stray light.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method of cutting a glass substrate to obtain a glass substrate having high mechanical strength and cleanliness.

A method of cutting a glass substrate according to the present invention is a method of cutting a glass substrate by irradiating a laser beam with a light-converging point in a glass substrate having two light-projecting surfaces opposed to each other in the thickness direction, The method comprising the steps of: forming a scratch area serving as a starting point of cutting in the thickness direction of the substrate; generating cracks in the thickness direction of the glass substrate from the scratch area as a starting point; A method of cutting a glass substrate comprising a step of cutting the glass substrate, characterized in that the flaw region is separated from at least one of the light projecting surfaces.

The optical glass for a solid-state imaging device of the present invention is a glass substrate having two light-transmissive surfaces facing each other in the thickness direction and side surfaces between the two light-transmissive surfaces, Wherein the glass substrate is a cut surface formed by irradiating a laser beam to form a flaw area serving as a starting point of cutting in the thickness direction of the glass substrate along a line along which the object is intended to be cut and by extending the flaw area, And a distance between the at least one of the light-transmitting surfaces is 20% or more with respect to the thickness of the glass substrate.

According to the cutting method of the glass substrate of the present invention, it is possible to provide a glass substrate provided with high mechanical strength and cleanliness (that is, the glass substrate does not generate machining residue at the time of cutting).

1 is a cross-sectional view schematically showing a cutting method of a glass substrate according to the present invention.
2 is a cross-sectional view of a solid-state imaging device using a glass substrate cut by the cutting method of the glass substrate of the present invention.

A method of cutting a glass substrate of the present invention (hereinafter, sometimes referred to as a cutting method of the present invention) is a method of cutting a glass substrate having two light projecting surfaces 6 and 6 facing each other in the thickness direction Lt; / RTI >

According to the cutting method of the present invention, it is possible to cut a glass substrate without forming a crack on the ridge of the cut portion of the glass substrate, thereby providing a glass substrate having high mechanical strength and high transparency of the light transmitting surface.

According to the cutting method of the present invention, laser light is irradiated while converging a light-converging point inside a glass substrate having two light-projecting surfaces (6, 6) facing each other in the thickness direction, Forming a scratch area serving as a cutting starting point in the thickness direction of the glass substrate; generating cracks in the thickness direction of the glass substrate from the scratch area as a starting point; And cutting the substrate. In the step of forming the scratch area, the scratch area has a feature of being separated from at least one of the light-projecting surfaces.

Hereinafter, each step will be described in detail with reference to Fig.

In the step of forming the flaw region, the flaw region 3 is formed in the glass substrate 1 by irradiating the laser light 2 with the light-converging point in the glass substrate 1. [ When a laser beam 2 having a predetermined energy intensity is irradiated to the glass substrate 1 so as to be condensed in the glass substrate 1, the portion where the laser beam 2 is condensed is irradiated onto the laser beam 2 And is expanded. As a result, a pressure due to thermal expansion is applied to the periphery of the region where the laser beam 2 is condensed. However, in the region outside the portion pressed by the thermal expansion, that is, the region where the laser beam 2 is not irradiated, the heating effect by the laser beam 2 is not affected, and the laser beam 2 is not irradiated The region constrains the portion to be pressed by the thermal expansion. As a result, the region where the laser beam 2 is condensed is thermally deformed between the region where the laser beam 2 is not irradiated and the scratch region 3 is formed in the glass substrate 1. Here, the region where the laser light 2 is condensed becomes a starting point of the scratch region 3. [ The scratch area 3 is formed by extending the scratch from the starting point toward the light-transmitting surface.

It is important that the scratch area 3 formed inside the glass substrate 1 is separated from at least one of the light transmissive surfaces 6 of the glass substrate 1. [ If a conventional cutting method in which a crack serving as a starting point of cutting is formed by a laser or a scriber on the light projecting surface 6 on the line along which the glass substrate is to be cut is used as described in the conventional method of cutting the glass substrate, A crack (a scratch extending parallel to or perpendicular to the light-projecting surface) is generated in the ridge of the cut portion of the glass substrate after cutting. When a crack is present in the ridge of the cutting edge of the glass substrate 1, when the bending stress is applied to the glass substrate 1, the glass substrate 1 is liable to be cracked starting from the crack.

On the other hand, in the step of forming the scratch area in the cutting method of the present invention, the laser light 2 is irradiated with the light-converging point in the glass substrate 1 as described above, A scratch area 3 is formed. More specifically, a starting point of the scratch area 3 is formed in the glass substrate 1 by the laser beam 2, and a scratch extending from the starting point of the scratch area 3 toward the light- Thereby forming a scratch area 3. Therefore, even if the scratch area 3 is applied to the ridgeline of the line along which the object is intended to be cut on the glass substrate, it is possible to prevent the scratch area 3 from becoming a starting point of cutting by physical means on the projected surface 6 on the line along which the object is intended to be cut, Cracks are not formed on the ridge of the cut portion of the glass substrate. Thus, when bending stress is applied to the glass substrate 1, the glass substrate 1 does not easily crack because there is almost no crack as a starting point.

In the step of forming the scratch area in the cutting method of the present invention, the scratch area 3 formed in the glass substrate 1 is formed such that at least one of the scratch areas 3 is spaced from the glass substrate 1 1 or more of the plate thickness of the plate-like member. By doing so, cracks are not likely to be generated in the ridge of the cut portion of the light-projecting surface 6, which is distant from the scratch region 3 at the time of cutting. Therefore, when bending stress is applied to the glass substrate 1 so that the side of the light transmitting surface 6 in which the generation of cracks is suppressed is convex, the possibility of cracking of the glass substrate 1 is low and the bending strength becomes high. In the case where bending stress is applied to the glass substrate 1 so as to be convex at the time of use of the glass substrate, at least one of the light-projecting surfaces 6 in the present invention has a light- 6).

If the distance between the scratch area 3 and the transparent surface 6 of the scratch area 3 is less than 20% of the thickness of the glass substrate 1, the scratch area 3 from the scratch area 3 at the time of cutting the glass substrate 1 There is a risk of being formed as a crack on the ridge of the cut portion of the light-projecting surface 6. If a crack is formed in the ridge of the cut portion, the bending strength of the glass substrate 1 is lowered, which is not preferable. The distance of the scratch area 3 from the light-transmitting surface 6 is preferably 25% or more, more preferably 28% or more of the thickness of the glass substrate 1.

The scratch area 3 formed inside the glass substrate 1 refers to a scratch area 3 formed inside the glass substrate 1 formed by the irradiation of the laser light 2. [ Therefore, when the scratches are elongated in the thickness direction of the glass substrate 1, the area from the top end to the bottom end of the scratches becomes the scratch area 3 in the present invention.

The scratch region 3 is formed along the line along which the glass substrate 1 is to be divided. In short, scanning is performed by moving the laser light 2 in a direction parallel to the light-projecting surface 6 of the glass substrate 1 while condensing the laser light 2 inside the glass substrate 1. [ As a result, the scratch area 3 is formed continuously along the line along which the glass substrate 1 is to be cut. The scratch area 3 formed along the line along which the object is intended to be cut in the glass substrate 1 may be provided singly or may be plural for one line along which the object is intended to be cut. In other words, the flaw region 3 is formed along the line along which the substrate is to be cut on the glass substrate 1, and then the laser beam 2 is condensed at a position different from the light-converging point of the laser light 2 formed first, Thereby forming a scratch area. By repeating this, a plurality of scratch regions 3 may be formed on the line along which the object is intended to be divided.

The laser light 2 used in the cutting method of the present invention is preferably pulsed laser light. When pulse laser light is used, the wavelength, pulse width, repetition frequency, irradiation time, and energy intensity may be arbitrarily set in accordance with the thickness of the glass substrate 1, the size of the formed scratch area 3, and the like.

As the laser beam 2, a so-called picosecond laser having a pulse width in the range of 5 ps to 100 ps (ps: picosecond) can be preferably used. Such a laser beam 2 has small scratches formed inside the glass substrate 1 by the irradiation of the laser beam 2 once. When the frequency of the laser light 2 is increased by repeating the laser light 2, a scratch area 3 formed of a plurality of minute scratches is formed. Such a scratch area 3 contributes to the improvement of the cleanliness of the glass substrate 1 since cutting residues and the like are not generated from the side surface of the glass substrate 1 after cutting the glass substrate 1.

The step of cutting the glass substrate 1 is carried out by applying a bending load such that the translucent surface 6a on the side closer to the distance between the scratch area 3 and the light projecting surface 6 is convex, 1) is bent. 1, a bending load is applied to the glass substrate 1 in a direction substantially perpendicular to the glass substrate 1 from the lower light-transmitting surface 6b toward the upper light-transmitting surface 6a. Stress is applied to the glass substrate 1 by the bending division and the flaws are stretched in the thickness direction from the scratch area 3 formed in the glass substrate 1 so as to cut the glass substrate 1 The glass substrate is cut along the line. 1, the distance 8 between the scratch area 3 and the light projecting surface 6b is larger than the distance 7 between the scratch area 3 and the light projecting surface 6a, and the lower light projecting surface 6b is located on the upper side And is far away from the scratch area 3 as compared with the light-transmissive surface 6a.

The reason why the translucent surface 6a on the side closer to the distance between the scratch area 3 and the light projecting surface 6 is subjected to a bending stress in a convex shape in the step of cutting the glass substrate 1, This is because the glass substrate 1 can be cut with a small bending stress. When the glass substrate 1 is folded and divided, a crack or a defect is generated on the cut surface of the glass substrate 1 by an impact at the time of cutting. Therefore, cracks or defects can be suppressed from being generated in the ridge of the cut portion of the light-transmitting surface 6 by bending and dividing with a small bending stress, and the glass substrate 1 after cutting has high mechanical strength and cleanliness. When the bending stress causing convex shape on the side far from the scratch area 3 and the light projecting surface 6b is applied, the distance between the scratch area 3 and the light projecting surface 6b is far, It is feared that the shape of the glass substrate 1 after cutting is deteriorated because the flaws extended from the region 3 deviate from the line along which the object is intended to be cut or zigzag.

The cutting method of the glass substrate 1 is not limited to the cutting method by the bending division, but a known cutting method may be used. For example, a method may be used in which the glass substrate 1 is attached to a stretchable adhesive sheet, and the stress is applied in the plane direction of the glass substrate 1 by pulling the adhesive sheet.

As the material of the glass used in the cutting method of the present invention, any material may be used. For example, various glass materials such as borosilicate glass, quartz glass, alkali-free glass, aluminosilicate glass, phosphate glass, fluorophosphate glass, and soda lime glass can be suitably used. As a glass substrate, a white plate glass having excellent optical characteristics and an infrared absorbing glass for absorbing infrared rays can be preferably used.

A function film may be formed on the light-projecting surface 6 of the glass substrate 1. [ The functional film is an optical film made of a single layer or a plurality of metal oxides or metal fluorides and has appropriate optical characteristics such as reflection prevention, infrared ray blocking, ultraviolet ray blocking, ultraviolet ray and infrared ray blocking.

The glass substrate cut by the cutting method of the present invention has a thin plate thickness and is used in applications where a bending stress is applied in use, for example, in a cover glass or an optical filter of the above-mentioned solid- Quot; optical glass "). At this time, it is preferable that the light projecting surface 6a on the side closer to the distance between the scratch area and the light projecting side is the side of the package of the solid state imaging device or the side of the attaching portion to the other optical filter.

The reason is that the ridge of the cut portion of the translucent surface near the distance between the scratch area and the translucent surface is more cracked than the ridge of the cut portion of the other translucent surface. Therefore, by bonding the translucent surface 6a on the side closer to the scratch area 3 and the translucent surface to the other member, the ridge of the cut portion of the translucent surface is fixed. Therefore, when bending stress acts on the glass substrate, The extension is suppressed. On the contrary, even if the translucent surface on the side far from the scratch area and the translucent surface has a very small crack of the ridgeline, even if the bending stress causing the convex surface of the ridgeline acts on the glass substrate, So that the glass substrate exhibits high bending strength.

2 is a cross-sectional view of the solid-state imaging device 10. As shown in Fig. The solid-state imaging device 10 is formed by hermetically sealing a protective light-transmitting member 13 in a package 12 containing an imaging element 11 formed of CCD or CMOS. The near-infrared cut filter glass 15, which is an optical filter, and the low-pass filter 14 are formed by bonding on the object side of the package 12. When the protective light transmitting member 13 is cut by using the cutting method of the glass substrate of the present invention, the concave surface of the protective light transmitting member 13 with the package 12 is located on the side close to the scratch area and the light transmitting surface Is preferably the light-projecting surface 6a of the projection lens 6a. When the near-infrared cut filter glass 15 is cut using the cutting method of the present invention, the surface of the near-infrared cut filter glass 15 that is adhered to the low-pass filter 14 is set such that the distance between the cut- It is preferable that the projection surface 6a is a near side. In this way, when the protective light transmitting member 13 or the near-infrared cut filter glass 15 is used for the solid-state image pickup device 10 for the reason described above, breakage of each glass substrate can be suppressed.

The method of cutting a glass substrate according to the present invention is characterized in that a flaw region is separated from at least one light-projecting surface. In addition, the flaw region may be separated from the other light-projecting surface. In such a case, there is almost no crack in the ridge of the cut portion of the two light-projecting surfaces, so that even if bending stress is applied to the glass substrate to make the light-projecting surface of the convex surface on either side be applied to the glass substrate, So that it is possible to have a high mechanical strength.

In the case where the scratch area 3 is formed in the glass substrate by being separated from the transparent surfaces 6 and 6 on both sides of the glass substrate 1 as described above, Preferably, 5% or more and 50% or less of the thickness of the glass substrate 1 from the light-transmissive surfaces 6 and 6 on both sides of the glass substrate 1. [

The optical glass for a solid-state imaging device of the present invention is a glass substrate having two light-transmitting surfaces facing each other in the thickness direction and side surfaces between the two light-transmitting surfaces. The side surface is formed by irradiating a laser beam with a light-converging point in the glass substrate and forming a flaw region serving as a starting point of cutting in the thickness direction of the glass substrate along the line along which the object is intended to be cut and by extending the flaw region It is a cut surface. The scratch area on the side surface is preferably at least 20% of the thickness of the glass substrate with respect to at least one of the light-transmitting surfaces. By doing so, cracks are not likely to be generated in the ridge of the cut portion of the light-projecting surface 6, which is distant from the scratch region 3 at the time of cutting.

When it is assumed that a bending stress acts on the glass substrate and the convex surface becomes convex in a manufacturing process or a situation where the glass substrate is used, the distance between the scratch area and the light- The light-projecting surface spaced by 20% or more from the light-projecting surface is preferably the light-projecting surface which becomes the convex shape.

The optical glass for a solid-state imaging device according to the present invention is characterized in that the surface roughness Ra of the scratch area on the side surface is 1.0 to 3.0 占 퐉 and the surface roughness of the unscratch area between the scratch area and the light- Ra of 0.01 to 0.5 mu m is preferable. By doing so, the ridge line between the light projecting surface and the side surface is in a state of a very small crack, and the bending strength of the glass can be increased. The non-scratch area is a point other than the scratch area on the side surface of the glass. The optical glass for a solid-state imaging device of the present invention has a non-scratch area on a side surface between a scratch area and at least one of the light-transmissive surfaces. It is more preferable to provide a non-scratch area between the upper and lower light-projecting surfaces and the scratch area. If the surface roughness Ra of the non-scratch area is less than 0.01 탆, processing is difficult. On the other hand, if it exceeds 0.5 탆, the mechanical strength of the glass may be lowered. The surface roughness Ra of the non-scratch area is preferably 0.02 to 0.3 mu m.

In the optical glass for a solid-state imaging device according to the present invention, it is preferable that the width of the scratch area on the side surface in the thickness direction is 15% to 60% of the thickness of the glass substrate. In the solid-state imaging device, when light is incident from the lens side, the light reflected from the surface of the solid-state image sensing device becomes stray light, and there is a case where the inside of the device is subjected to multiple reflection to affect the sensed image. Here, since a part of the side surface of the glass becomes a flaw area, the stray light incident on the side surface of the glass is irregularly reflected, and the influence on the picked-up image can be reduced. If the surface roughness Ra of the scratch area on the side surface of the glass is less than 1.0 탆, the effect of diffusing the stray light is reduced. If the surface roughness Ra exceeds 3.0 탆, glass residues from the scratch area may be generated during transportation of the glass. It is more preferable that the surface roughness Ra of the scratch area on the side surface of the glass is 1.2 to 2.5 占 퐉.

It is preferable that the optical glass for a solid-state imaging device of the present invention is a high-transmittance glass (generally, white plate glass). A white plate glass is a glass produced by melting a raw material having a high purity and containing a small amount of impurities such as an iron component and has a high transmittance in the wavelength range of visible light. Specifically, B270 glass (manufactured by SCHOTT) or BK7 glass (manufactured by SCHOTT), and glass having properties similar to those mentioned above. It is preferable that the white board glass be provided with an antireflection film or an infrared ray blocking film on at least one of the light projecting surfaces.

Example

Hereinafter, the present invention will be described in detail based on examples of the present invention, but the present invention is not limited to these examples.

In each of the following examples (Examples 1 to 3) and Comparative Examples (Examples 4 and 5), a white plate glass (B270 glass manufactured by Shot Corporation, size: 6 inches x 6 inches , Thickness: 0.3 mm) were prepared.

In Examples 1 to 4, the glass substrate 1 was cut into a rectangular shape of 50 mm x 20 mm under the following conditions. The conditions for the formation of the flaw area used in each example were laser (wavelength: 1064 mm, pulse width: 30 psec (picosecond), frequency: 1 MHz), processing speed: 100 mm / to be. Further, in the step of cutting the glass substrate, the glass substrate was cut into pieces along the line along which the substrate should be cut by bending division. The focal length 4 or the number of times of scanning of the laser beam was set so as to form the flaw area 3 shown in Table 1. [ The laser light was focused in the vicinity of the center in the thickness direction of the glass substrate 1. In Example 1 and Example 4, the distance between the upper surface light-transmitting surface and the scratch area is 0 占 퐉. This is because the starting point of the scratch area is formed near the center of the glass substrate by the laser light, It means that the scratches have been stretched so as to be reached.

In Example 5, the glass substrate 1 was cut into a rectangular shape of 50 mm x 20 mm under a condition of a # 600 blade and a processing speed of 3 mm / sec using a dicing machine. In the step of cutting the glass substrate, the glass substrate was cut into pieces along the line along which the material was intended to be cut by bending and dividing as in Examples 1 to 4.

Subsequently, with respect to each single glass substrate of each example, the distance from the respective light-transmitting surfaces to the scratch area (the distance 7 from the upper light-transmitting surface to the scratch area and the distance 8 from the lower light-transmitting surface to the scratch area) The strength was measured. The bending strength P (N) was measured and the bending strength (MPa) was calculated based on the three-point bending strength test described in JIS R 1601: 2008 "Bending strength test method of fine ceramics". In the bending strength test, a bending strength test was carried out with the upper light-transmitting surface of Table 1 up. Further, the distance between the scratch area and each of the light-projecting surfaces and the bending strength indicate the average value measured for each of the five images. Note that the upper side translucent surface in Table 1 refers to the side on which the bending stress for bending the glass substrate acts and the lower side translucent side refers to the opposite side.

Example 1 Example 2 Example 3 Example 4 Example 5 Distance between the upper light-transmitting surface and the scratch area [占 퐉] 0 15 30 0 0 Distance between the lower light-transmitting surface and the scratch area [탆] 230 104 85 20 0 Distance between the lower light-transmitting surface and the scratch area / plate thickness 77% 35% 28% 7% 0 % Bending strength [MPa] 304 335 290 113 150

From the above, it can be seen that by using the cutting method of the glass substrate of the present invention, a glass substrate having a high bending strength can be obtained. Especially when the bending stress acts on the glass substrate, the distance between the light projecting surface on the convex side and the scratch area is set to 20% or more of the thickness of the glass substrate, so that the glass cut by the conventional cutting method such as dicing It can be seen that a glass substrate having a large bending strength is obtained in comparison with a substrate.

Next, for the glass substrate after cutting in Example 1 and Example 5, the width of the flaw area on the side (cut surface), the surface roughness Ra of the flaw area, and the surface roughness Ra of the non-flaw area were checked. The glass substrate of Example 1 shows an average value because there is a non-flaw region on the upper and lower sides of the flaw region. The results are shown in Table 2.

Example 1 Example 5 Surface roughness
Ra [占 퐉] Scratch area 2.01 1.20 Non-scratch area 0.09 - Width of scratch area
[%] 25% 100%
(Entire surface scratch area)

From Table 1 and Table 2, the glass substrate of Example 1 has a non-scratch region having a very small surface roughness (Ra) on the upper and lower sides of the scratch region, and thus has a higher bending strength than the glass substrate of Example 5. Further, since the glass substrate of Example 1 has a surface roughness (Ra) of a scratch area on a side surface of 1.0 占 퐉 or more, when used in an optical glass for a solid-state imaging device, scattered stray light on a side surface is scattered, It is presumed that it can be done. On the other hand, the glass substrate of Example 5 has a side surface roughness Ra of 1.0 m or more, so that the effect of scattering stray light can be obtained. However, since the entire side surface is a flaw region, Strength is low.

Industrial availability

By using the cutting method of the glass substrate of the present invention, for example, the cover glass or the optical filter used in the solid-state imaging device can be cut as a glass substrate having high mechanical strength and cleanliness.

The entire contents of the specification, claims, drawings and summary of Japanese Patent Application No. 2011-179651 filed on August 19, 2011 are hereby incorporated herein by reference as the disclosure of the present invention.

1: glass substrate,
2: laser light,
3: scratch area,
4: Focal length,
6: Projection surface,
6a: a light-projecting surface on the side where the distance between the scratch area and the light-
6b: a light-projecting surface on the far side of the scratch area and the light-projecting surface,
7: distance between the scratch area and the light projecting surface,
8: Distance between the scratch area and the light-projecting surface,
10: Solid state imaging device,
11:
12: Package,
13: protective light transmitting member (cover glass),
14: Low pass filter,
15: near-infrared cut filter glass.

Claims (9)

A laser beam is irradiated to the inside of the glass substrate provided with two light-projecting surfaces opposing in the plate thickness direction, and a laser beam is irradiated along the line along which the glass substrate is to be cut, A step of forming a flaw region to be formed,
Cutting the glass substrate along the line along which the object is intended to be cut by causing cracks to be generated in the thickness direction of the glass substrate from the scratch area as a starting point,
Wherein the flaw area is separated from at least one of the light-
Wherein the side surface of the glass substrate after cutting has a surface roughness Ra of 1.0 to 3.0 占 퐉 in the scratch area and a surface roughness Ra of 0.01 to 0.5 占 퐉 in a non-scratch area between the scratch area and the light- Method for cutting optical glass for a device. The method according to claim 1,
Wherein the scratch area has a distance from at least one of the light-projecting surfaces to a thickness of the glass substrate of 20% or more. 3. The method according to claim 1 or 2,
Wherein the step of cutting the glass substrate comprises bending and dividing the glass substrate by applying a bending load such that the light projecting surface on the side closer to the distance between the scratch area and the light projecting surface is convex, Method of cutting optical glass. 3. The method according to claim 1 or 2,
Wherein the laser light is a picosecond laser. 3. The method according to claim 1 or 2,
Wherein the scratch area is formed inside the glass substrate by being separated from the light projecting surface of both surfaces of the glass substrate. 3. The method according to claim 1 or 2,
Wherein the scratch area on the side of the glass substrate after cutting is at least 20% of the thickness of the glass substrate with respect to at least one of the light-transmitting surfaces. 3. The method according to claim 1 or 2,
Wherein the scratch area of the side surface of the glass substrate after cutting is 15% to 60% of the thickness of the glass substrate in the thickness direction of the glass substrate. 3. The method according to claim 1 or 2,
Wherein the glass substrate is a white plate glass. delete

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