JP5064711B2 - Glass substrate cutting method and optical filter - Google Patents

Description

  The present invention relates to a method for cutting a thin glass substrate, which can improve the bending strength of the glass substrate after cutting as compared with the conventional cutting method by setting the crack length generated at the time of cutting the glass substrate to a certain value or less. .

  As a method of cutting a glass substrate such as an optical filter, the glass substrate is supported by a support base such as a surface plate, a linear scribe groove is formed by a cemented carbide scribe roller, and then the portion where the scribe groove is formed is reversed. A scribe cutting method is used in which a scribe cutting is performed by pressing from the side and growing a crack starting from the bottom of the scribe groove in the thickness direction by the pressing force.

As another method for cutting a glass substrate, there is a method using a dicing blade. In this method, a V-groove (inclined surface) is formed on the planned cutting line of the glass substrate and then reversed. Similarly, after forming a similar V-groove on the planned cutting line on the opposite surface, a full cut is made along the V-groove. (Patent Document 1, Patent Document 2)
JP-A-9-141646 JP 2004-142428 A

  With recent downsizing and thinning of optical devices such as digital cameras, glass substrates such as optical filters used for these devices are required to be thinner. Since glass substrates such as optical filters are fixed and used by bonding with optical equipment and other members, the decrease in bending strength due to thinning is not particularly problematic and is not considered in conventional cutting methods. It was. However, when the glass substrate is thinned, the bending strength is particularly lowered, and the problem that the glass substrate is broken due to the action of a slight force during transportation of the manufacturing process or when the product is incorporated has become apparent.

As a method for improving the bending strength of a glass substrate, it is generally known to perform physical strengthening (wind cooling strengthening) or chemical strengthening. However, when the thickness of the glass substrate is very thin, the compressive stress layer cannot be sufficiently inserted even if air cooling strengthening is performed, and it is difficult to improve the bending strength. Even if a compressive stress layer can be formed, it is difficult to equalize the stress balance between the front and back surfaces of a thin glass substrate, and it is not applicable to applications that require optical or mechanical surface accuracy because it causes warping. .
In addition, the optical filter exhibits functions such as selectivity of a specific wavelength depending on its glass composition. Therefore, when a glass composition is partially replaced by performing chemical strengthening, it is expected that the function as an optical filter will be affected. Therefore, it is difficult to employ chemical strengthening for glass substrates such as optical filters.

  In the case of the above-mentioned scribing method, a scribing roller that is rotatably supported is run in the plate surface direction with pressure applied to the glass substrate to form a scribing groove. However, there is a problem that the scribe roller is liable to generate a slight shaft runout, a shaft collapse, etc., for example, a crack that extends from the scribe groove toward the plate surface of the glass substrate. Further, in order to suppress the occurrence of chipping of the end face that occurs in the polishing process subsequent to the cutting, ridge line chamfering using a centering machine is generally performed in the previous process of the polishing process. However, there is a problem that the ridge line chamfering process needs to be performed on four sides and eight ridge lines, and a long time is required for the processing.

  In the case of the cutting method using the dicing blade described in the patent document, it is said that there is an effect of preventing chipping during cutting by forming the V groove. However, there is no disclosure about the relationship between the crack generated in the cut surface and the bending strength of the glass substrate.

  This case is based on such a background, and aims to improve the bending strength of a glass substrate such as an optical filter, which has not been a problem in the past, by devising a cutting method.

  The present inventor is a method for cutting a glass substrate using a dicing blade, particularly focusing on a crack generated on a V-groove forming surface, and by reducing the size of the crack as much as possible, the bending strength of the glass substrate can be reduced. I thought it could be improved.

The present invention includes a step of forming a V groove with a V-shaped dicing blade on a planned cutting line on one side of a glass substrate to form a first V groove forming surface that is chamfered, and a surface opposite to the one side. Forming a V-groove with a V-shaped dicing blade on the planned cutting line to form a second V-groove forming surface that is chamfered , and the first and second surfaces on one surface and the opposite surface of the one surface ; after forming the V-groove forming face, and a step in which the V V groove forming surface of a thin dicing blade than the groove width of the first and second grooves are cut the glass substrate so as to leave a ridge portion, the a V-shaped dicing blade have an average abrasive grain size is not 13μm is 28 .mu.m, and a resin bond blade or resin - a metal-bond blade or metal-bond blade, the maximum crack length of the V-groove forming surface 0. It is a method for cutting a glass substrate, characterized by a 2mm or less. Thereby, since the crack of the V-groove formation surface which is a factor of the bending strength fall of a glass substrate is small, bending strength more than fixed can be obtained.

Further, the V-shaped dicing blade has an average abrasive grain size of 28 μm or less, and is a resin bond blade, a resin-metal bond blade or a metal bond blade.
Thereby, the crack of the V-groove formation surface of a glass substrate can be made small. In addition, since the abrasive grains fixed to the V-shaped dicing blade are fixed with resin or metal powder, the abrasive holding power is weak and the abrasive grains are softly hit against the glass substrate, so that V-groove formation Surface cracks can be reduced.

The glass substrate has a thickness of 0.1 to 1.0 mm.
Thereby, it can use suitably with respect to the cutting | disconnection of the thin glass substrate for which physical strengthening is difficult.

The glass substrate is an optical filter.
Thereby, it can use suitably with respect to the cutting | disconnection of the glass substrate for the optical filter use to which application of chemical strengthening is difficult.

  According to the present invention, when the V groove (inclined surface) is formed on the planned cutting line of the glass substrate with the V-shaped dicing blade, the maximum crack length of the V groove forming surface is set to 0.02 mm or less. Compared with the conventional method for cutting a glass substrate, the bending strength of the glass substrate after cutting can be improved.

FIG. 1 is a flowchart showing an embodiment of a glass substrate manufacturing method including the cutting method of the present embodiment.
Hereinafter, the process flow from the glass raw material to the glass product will be briefly described with reference to FIG. First, a glass raw material is melted and formed to obtain a flat glass plate (glass plate forming step). The glass plate is polished and finished to a mirror surface (polishing step), and the glass plate is washed to sufficiently remove abrasives and polishing debris (first cleaning / drying step). A film such as an antireflection film or a near-infrared cut film is formed on the polished surface of the glass plate thus obtained as necessary (film formation step). Next, the glass plate is cut into predetermined dimensions (cutting step). When cutting, the ridge line chamfering process of the end face of the glass substrate is also performed at the same time. And a glass substrate is wash | cleaned and cutting waste is fully removed, and it dries (2nd washing | cleaning and drying process). Thereby, a glass product is obtained.

  In the glass plate forming step, the prepared glass raw material is melted in a glass melting furnace, and the molten glass flows out of the glass melting furnace into a forming die and is formed into a plate-like glass. Alternatively, after forming into block-shaped glass, it is cut into a plate shape.

  By performing the polishing step in a state of a glass plate having a relatively large size before being cut into a glass substrate having a predetermined size, the polishing step can be performed stably, and a good polished surface can be obtained. This polishing process is performed in, for example, the steps of rough polishing, intermediate polishing, and mirror finishing, thereby obtaining good dimensional accuracy and a good finished surface.

  In the first and second cleaning / drying steps, the abrasive, polishing waste and cutting waste used for polishing are removed by cleaning. For example, a method in which a glass plate is housed and held in a cage having a holding portion that holds the glass plates one by one, and the cage is sequentially immersed in an ultrasonic cleaning tank for cleaning, and finally IPA cleaning and drying are performed. Can be used.

  The film forming step is a step of forming a thin film such as an antireflection film or a near-infrared cut film on the plate surface of the glass plate that has been polished, washed and dried, as necessary. In an optical filter such as a cover glass or a visibility correction filter used for the solid-state imaging device, an antireflection film for reducing a reflection loss of incident light is formed by a vacuum vapor deposition apparatus or a sputtering apparatus. In some cases, a near-infrared cut film is formed on the cover glass, thereby omitting the visibility correction filter. In the case of an optical filter that does not require a thin film as described above, the film forming step may be omitted. Moreover, you may perform a film-forming process with respect to the glass substrate after a cutting process.

  Although not shown in FIG. 1 showing one embodiment of the method for producing a glass substrate, a coating agent may be applied to the end surface including the V groove forming surface of the glass substrate after the second cleaning / drying step. . As the coating agent, a UV curable resin such as an acrylic resin, an acrylic urethane resin or an enethiol resin, a thermosetting resin such as an epoxy resin, a curable coating composition containing polysilazane, or the like can be used. The coating method is performed by brush coating, roll coating, spray coating, dipping coating, or the like. Thereby, since a coating agent osmose | permeates and hardens | cures the crack of a V-groove formation surface, the expansion | extension of a crack can be suppressed and the bending strength of a glass substrate can be improved more.

Next, the cutting process of this embodiment is demonstrated in detail using FIG.
FIG. 2A shows a step of forming a first dicing groove 6 (V groove) with a V-shaped dicing blade 4 on a planned cutting line on one surface (first dicing surface 2) of the glass substrate 1 (first). A dicing process) is shown. In the first dicing step, a first dicing groove 6 having inclined surfaces on both surfaces is formed along a predetermined cutting line using a V-shaped dicing blade 4. At this time, the processing depth of the first dicing groove 6 is set to a depth less than the thickness of the glass substrate 1 so as not to cut the glass substrate 1. Further, the glass substrate 1 and the processing table 11 are fixed by adhering an ultraviolet curable dicing tape 10 to the glass substrate 1 and vacuum-adsorbing the ultraviolet curable dicing tape 10 to the processing table 11.

  Next, FIG. 2B shows an inversion process for inverting the glass substrate 1. In the inversion step of the glass substrate 1, the glass substrate 1 is inverted so that the opposite surface (second dicing processing surface 3) of the one surface becomes the processing side. At this time, as shown in FIG. 3, after the first dicing groove 6 is processed, the vacuum suction of the processing table 11 is released, and the glass substrate 1 removed from the processing table 11 is irradiated with ultraviolet rays, whereby the first ultraviolet curable dicing is performed. The tape 101 is cured to reduce the adhesive force. And after sticking the 2nd ultraviolet curing dicing tape 102 on the 1st dicing process surface 2, the glass substrate 1 is reversed and the 1st ultraviolet curing dicing tape 101 of the 1st dicing process surface 2 in which adhesive strength fell The glass substrate 1 is inverted by removing.

  Next, FIG. 2C shows a step of forming the second dicing groove 7 (V groove) on the second dicing surface 3 and then cutting the glass substrate 1 with a dicing blade 5 thinner than the groove width of the V groove ( 2nd dicing process) is shown. Before performing the second dicing process, the position of the glass substrate 1 is accurately adjusted so that the first dicing groove 6 on the first dicing surface 2 and the second dicing groove 7 on the second dicing surface 3 are not displaced. This is very important.

  The position adjustment is performed by inverting the glass substrate 1 and detecting the first dicing groove 6 of the first dicing surface 2 from the second dicing surface 3 side with a CCD or the like. At this time, when the antireflection film is formed in the film forming process, the surface on which the antireflection film 8 is formed is used as the second dicing surface 3 to reflect the irradiation light on the second dicing surface. Therefore, the first dicing groove 6 on the first dicing surface 2 can be clearly recognized. Thereby, positioning of the glass substrate 1 can be accurately performed by CCD or visual observation. In addition, the cutting apparatus used for these cutting processes uses a dicing apparatus that attaches a dicing blade to the tip of the spindle and performs cutting by rotating the spindle at a high speed.

The cross-section V-shaped dicing blade used in the first and second dicing steps preferably has an average abrasive grain size of 28 μm (mesh: equivalent to # 600) or less. Thereby, the crack length which generate | occur | produces in the V-groove formation surface of a glass substrate can be made small, and the bending strength of a glass substrate can be improved. On the other hand, when a cross-sectional V-shaped dicing blade having an average abrasive grain size larger than 28 μm is used, the crack length generated on the V-groove forming surface of the glass substrate increases, leading to a decrease in the bending strength of the glass substrate.
In addition, by using a V-shaped dicing blade having a finer average abrasive grain diameter, it is possible to reduce the length of cracks generated, but the processing speed is slow and the influence of heat on the processing surface is large. Therefore, when these are considered comprehensively, those having an average abrasive grain size of up to 13 μm (mesh: equivalent to # 1200) are preferably used. In addition, the crack length of the V-groove forming surface of the glass substrate in the present invention refers to the surface of the glass substrate (polishing surface) or a crack extending inward from the V-groove forming surface, and the crack is projected onto the surface of the glass substrate. It indicates the length of the crack in the case. The V-groove forming surface means an inclined surface of a cut end surface formed by a V-shaped dicing blade in the first and second dicing steps.

  The cross-sectional V-shaped dicing blade used in the first and second dicing steps is preferably a resin bond blade, a resin-metal bond, or a metal bond blade. The resin bond blade is a blade in which a binder for bonding abrasive grains is made of a resin agent. The metal bond blade is a blade formed by sintering abrasive grains and metal powder. The resin-metal bond blade is a blade having both. Since these blades have a weak abrasive grain holding force and are soft to the glass substrate during processing, cracks generated on the V-groove forming surface can be reduced. On the other hand, in the case of an electrodeposition blade in which the abrasive grains are electrodeposition-fixed, the base metal and the abrasive grain holding force are strong, and the contact with the glass substrate at the time of processing is strong. This is not preferable. When the resin bond blade and the metal bond blade are compared, the resin bond blade has a smaller abrasive length, but the crack length is smaller, but the life of the blade is shorter. On the contrary, the metal bond blade has a longer crack life, but the life of the blade is longer as the abrasive holding power is greater. Therefore, an appropriate type of bond can be selected and used depending on the glass material of the glass substrate. As the abrasive grains, appropriate ones such as diamond can be used.

The difference between cracks and chipping defined in the present invention will be described with reference to FIG.
FIG. 4A is a diagram schematically showing chipping generated on the end face of the glass substrate. Chipping refers to a surface chip at the ridge line portion that occurs when a glass substrate is cut or a V-groove is formed. Chipping causes glass powder and chipping problems due to vibration and contact with other members when the glass substrate is transported or incorporated into a product. In the drawing, one chipping is shown for the sake of explanation, but in reality, such a chipping occurs frequently at the edge portion.
FIG. 4B is a diagram schematically showing cracks generated on the end face of the glass substrate. A crack refers to a crack in a ridge line portion that occurs when a glass substrate is cut or a V-groove is formed. Cracks do not cause problems such as chipping in vibration or contact with other members. However, when bending stress acts on the glass substrate, the cracks extend and the glass substrate is broken. On the other hand, when a bending stress acts on the glass substrate in which only chipping occurs at the ridgeline portion, chipping is generated from chipping, but crack elongation that leads to breakage of the glass substrate is not observed. This is presumably because chipping occurs in a direction parallel to the ridge line portion of the glass substrate, and chipping extends in the central direction of the glass substrate. Cracks frequently occur in the center of the glass substrate, and the crack length is a factor that determines the bending strength of the glass substrate.

  In the following examples and comparative examples, an infrared cut filter glass (fluoric acid-based glass) having a size of 33.7 mm × 50.8 mm and a thickness of 0.3 mm was applied as the glass substrate. The glass substrate manufacturing process is performed in accordance with the flow chart shown in FIG. 1 (however, no film forming process is performed), and only the cutting process is changed to the cutting method of the present invention (Example) and the conventional cutting method (each comparative example). The bending strength of the cut glass substrate was measured. The enlarged photographs shown in the examples and comparative examples are taken of the boundary portion between the surface (polished surface) of the glass substrate and the V groove forming surface.

(Example)
In the cutting method of the example, the entire ridge line portion was chamfered and cut using a Tokyo Seimitsu dicer apparatus (A-WD-200T). The V-shaped dicing blade used for chamfering was a resin-metal bond blade # 600 (average abrasive grain size: 28 μm, abrasive grain type: diamond). When the V-groove formation surface of the glass substrate was confirmed with a microscope, chipping was confirmed, but cracks were not observed. FIG. 5 shows an enlarged photograph (× 500) of the V groove forming surface.

(Comparative Example 1)
In the cutting method of Comparative Example 1, the cutting process was performed in two stages: cutting by a scribe cutting method and chamfering of a ridge line portion by a centering machine. The grinding tool used in the centering machine is a # 600 electrodeposited diamond wheel. When the V-groove formation surface of the glass substrate was confirmed with a microscope, generation of chipping and cracks was observed. When the maximum crack length was confirmed, it was 0.06 mm. FIG. 6 shows an enlarged photograph (× 500) of the V groove forming surface.

(Comparative Example 2)
In the cutting method of Comparative Example 2, the same cutting process as that of Comparative Example 1 was performed, and then all ridges were manually polished into an R shape with a paper file (# 1000). When the V-groove formation surface of the glass substrate was confirmed with a microscope, no chipping was observed, but cracks that were thought to have occurred in the ridge line chamfering of the centering machine were not completely removed. When the maximum crack length was confirmed, it was 0.03 mm. FIG. 7 shows an enlarged photograph (× 500) of the V groove forming surface.

  About the Example and each comparative example, the maximum load when a test piece fractured | ruptured was measured using the 3 point | piece bending strength test method as described in JISR1601 (bending strength test method of fine ceramics). Table 1 shows the test results. The number of samples is 10 each.

  From the test results, it was confirmed that the examples had higher bending strength than the respective comparative examples. In Comparative Example 2, no chipping was observed, but the results were inferior to those of the Examples. This is presumably because the crack on the V-groove forming surface became the starting point of the break. On the other hand, although there was chipping in the examples, the maximum load at the time of fracture was higher than in each comparative example, so it was confirmed that the presence of chipping did not cause a decrease in bending strength.

  According to the present invention, when a glass substrate is cut, particularly when a V groove (inclined surface) is formed with a V-shaped dicing blade on the planned cutting line of the glass substrate, the maximum crack length of the V groove forming surface is set. By setting it to 0.02 μm or less, the bending strength of the glass substrate after cutting can be improved as compared with the conventional method for cutting a glass substrate.

It is the flowchart which showed one Embodiment of the manufacturing method of a glass substrate. It is the flowchart which showed the cutting process of this invention. It is a flowchart which shows the inversion process in the cutting process of this invention. It is the figure which showed typically the chipping and the crack which generate | occur | produced in the end surface of a glass substrate. It is an enlarged photograph of the V-groove formation surface of the glass substrate cut | disconnected by the cutting method as described in an Example. 4 is an enlarged photograph of a V-groove forming surface of a glass substrate cut by the cutting method described in Comparative Example 1. 6 is an enlarged photograph of a V-groove forming surface of a glass substrate cut by the cutting method described in Comparative Example 2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Glass substrate, 2 ... 1st dicing process surface, 3 ... 2nd dicing process surface, 4 ... Cross-section V-shaped dicing blade, 5 ... Dicing blade, 6 ... 1st dicing groove, 7 ... 2nd dicing groove, 8 DESCRIPTION OF SYMBOLS ... Antireflective film, 10 ... Dicing tape, 11 ... Processing stage, 21 ... Chipping, 22 ... Crack, 23 ... V groove formation surface, 24 ... Boundary of glass substrate surface (polishing surface) and V groove formation surface, 101 ... 1st ultraviolet curable dicing tape, 102 ... 2nd ultraviolet curable dicing tape.

Claims (4)

A step of forming a V groove with a V-shaped dicing blade on a cutting line on one side of the glass substrate to form a first V groove forming surface that is chamfered, and a cutting line on the opposite surface of the one side Forming a V-groove with a V-shaped dicing blade and forming a second V-groove forming surface that is chamfered ; and the first and second V-groove forming surfaces on one surface and the opposite surface of the one surface after forming the, and a step in which the V V groove forming surface of a thin dicing blade than the groove width of the first and second grooves are cut the glass substrate so as to leave a ridge line portion, the V-shaped cross section dicing blade have an average abrasive grain size is not 13μm is 28 .mu.m, and a resin bond blade or resin - a metal-bond blade or metal-bond blade, 0.02 mm at the largest value of the crack length of the V-groove forming surface A glass substrate cutting method which is characterized in that a.   The method for cutting a glass substrate according to claim 1 or 2, wherein the glass substrate has a thickness of 0.1 to 1.0 mm.   The method for cutting a glass substrate according to any one of claims 1 to 3, wherein the glass substrate is an optical filter.   It is an optical filter cut | disconnected with the cutting method of the glass substrate of Claim 1, Comprising: The maximum value of the crack length of a ridgeline part is 0.02 mm or less, and plate | board thickness is 0.1-1.0 mm An optical filter characterized by.