JP2005279977A - Method for cutting hard, brittle substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control the occurrence of the breakage of a cutting blade 4 and the chipping of a hard, brittle substrate 4 in the cutting of a hard brittle substrate 1 having minute unevenness 7. <P>SOLUTION: In a method for cutting the hard, brittle substrate having the minute unevenness 7 on the surface by the disk-like rotary blade 4, a smooth layer 8 of a material at least 30 in Shore's hardness is formed on the unevenness 7. The maximum height Ry of the surface of the smooth layer 8 is made to be 1/3 or below of the thickness of the rotary blade 4, and the smooth layer 8 and the hard brittle substrate 1 are cut. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a substrate cutting method for suitably cutting a hard brittle substrate having fine irregularities.

  Conventionally, in a hard brittle substrate such as sapphire, silicon, crystal, etc., the plate-like substrate is cut by fixing the hard brittle substrate 1 to the fixing jig 2 with an adhesive 3 as shown in FIG. 7, and using a slicing apparatus or dicing apparatus. Cutting may be performed by horizontally moving the rotated disk-shaped blade 4 with respect to the substrate. Further, in the case of a material having high hardness and a large thickness, the Z axis movement (cutting depth) of the blade 4 is cut in several stages.

  Here, when the depth of one cut is shallow, it is easily influenced by the shape of the substrate surface. Therefore, in general, the blade 4 has a thin thickness as much as possible in order to reduce the allowance for discarding the object to be cut and to reduce the cutting resistance and reduce chipping.

  The thickness of the blade 4 is generally 0.15 to 1.0 mmt. Since the thin blade 4 has no rigidity of the blade base 5, it is easily affected by the surface shape of the workpiece.

  In a hard brittle substrate, a substrate formed by crystal growth in a plate shape has many fine irregularities on the surface. In particular, single crystal sapphire produced by the EFG method (Edge-defined Film-fed Growth Method) that can efficiently produce a square plate-like substrate has a wide range of fine irregularities on the surface. The maximum height Ry of the surface of such a substrate is generally about 0.1 to 0.4 mm.

  In order to obtain a specified substrate size, the substrate is usually cut in a crystal-grown state (As-grown). If the surface irregularities are large and there is a hindrance to the cutting, the surface is temporarily removed. After grinding and removing the irregularities, cutting may be performed.

  As a reference technique, in Patent Document 1, in a cutting method of a hard material, cutting is performed so that the cutting resistance of the rotating grindstone is constant based on the amount of change in load current of a driving device for rotationally driving the rotating grindstone. A method has been proposed. Specifically, it is a method of monitoring the change of the load current value and changing the grinding wheel rotation speed and the grinding wheel feed speed to make the cutting resistance constant.

  Moreover, an adhesive sheet or an adhesive film may be used in order to protect surface scratches by cutting waste and prevent the cut end face from being detached.

For example, for the purpose of protecting the substrate surface at the time of cutting, Patent Document 2 comprises a partially crosslinked product of a partially neutralized carboxyl group-containing hydrophilic polymer, an anionic and cationic liquid surfactant, and an adhesive. Protective sheets and films have been proposed. Patent Document 3 proposes forming a water-insoluble protective film and cutting the substrate together with the protective film.
JP-A-7-227759 JP-A-7-2017787 JP-A-1-183133

  Of the hard brittle materials, sapphire, quartz, and the like are increasingly needed as optical parts such as a polarizer holding plate of a liquid crystal projector and a dustproof plate of a liquid crystal panel because of the superiority of transmittance and thermal conductivity. The optical component is usually used in the shape of a rectangular thin plate substrate. However, if there are defects such as chipping and cracks on four sides and four corners, incident light is irregularly reflected by the defects and affects the emitted light. Therefore, a processing process that does not generate chipping and cracks is desired in the manufacturing stage of the optical component.

  In the conventional method, as shown in FIG. 8, when the blade 4 reaches the fine unevenness 7 at the time of cutting, the blade 4 is guided to the shape of the unevenness 7 and the blade grindstone 6 having no rigidity of the blade 4 is tilted. For this reason, a load may be applied to the joint between the blade base 5 of the blade 4 and the blade grindstone 6 and the blade 4 may be damaged. In addition, even if the blade 4 is not damaged, a problem of meandering in the cutting direction occurs. There is. Further, depending on the shape of the unevenness 7, the tip of the blade grindstone 6 is unevenly worn, and the contact area with the substrate increases, so that the cutting resistance value increases, the load is applied to the apparatus, and the wear of the blade is accelerated.

  At the time of cutting, stress is concentrated particularly at the point at the convex portion, so that the occurrence of deep cracks and chipping on the cut substrate increases. Further, meandering of the blade 4 and a sudden change in the cutting resistance value also cause deep cracks and chipping.

  As a technique for solving this problem, it is conceivable to perform cutting after removing the surface irregularities 7, but there are problems such as an increase in cost due to an increase in the number of steps.

In Patent Document 1, in the case of the steep unevenness 7, there are many problems at the time when the load current changes, and current value control is followed, so that it is insufficient as a solution.

  In Patent Document 2, since the sheet and film have a constant thickness, the unevenness 7 on the surface of the substrate is reflected as it is even after sticking, or bubbles that do not stick to the sheet or film are generated around the convex part. It is not a solution. In Patent Document 3, as described above, the photoresist directly reflects the unevenness 7 on the surface of the substrate, and does not solve the above problem.

  Here, in order to solve the above-mentioned problems, the present invention provides a substrate cutting method for cutting a hard brittle substrate having fine irregularities on a surface with a disk-shaped rotating blade, from a material having a Shore hardness of 30 or more on the irregularities. The smooth layer is formed, the maximum height Ry of the surface of the smooth layer is set to 1/3 or less of the thickness of the rotating blade, and the smooth layer and the hard brittle substrate are cut together.

  Further, the flow viscosity at the time of forming the smooth layer is 300 cp or more.

  The material of the smooth layer is at least one of natural resins such as vinyl compounds, petroleum resins, rosin, and derivatives thereof.

  Further, the smooth layer contains fine abrasive grains.

  Furthermore, the substrate is bonded to a fixing jig using an adhesive made of the same material as the smooth layer.

  In a substrate cutting method in which a hard brittle substrate having fine irregularities on a surface is cut with a disk-shaped rotary blade, a smooth layer made of a material having a Shore hardness of 30 or more is formed on the irregularities, and the maximum surface of the smooth layer is formed. By making the height Ry 1/3 or less of the thickness of the rotating blade and cutting the smooth layer and the hard brittle substrate together, it becomes possible to continuously cut even the uneven substrate with a stable cutting resistance value. It is possible to prevent the occurrence of uneven wear and damage of the blade during cutting and the occurrence of chipping and cracking of the substrate.

  In the present invention, a smooth layer is formed on the upper surface of a substrate for cutting a hard brittle substrate having fine irregularities on the surface so that the maximum surface height Ry is 1/3 or less of the blade thickness with a material having a Shore hardness of 30 or more. The hard brittle substrate is cut together with the smooth layer.

  In the cutting process of the present invention, the hard brittle substrate 1 is attached to the fixing jig 2 via the adhesive 3 as shown in FIG. 1, and then the hard brittle substrate 1 as shown in FIGS. A smooth layer 8 is formed on the upper surface of the substrate. Next, as shown in FIG. 4, the smooth layer 8 and the hard brittle substrate 1 are simultaneously cut by setting in a cutting device.

  As a method for forming the smooth layer 8, a step of coating, surface shape shaping, and curing is required. As for the application, dipping, spraying, brush application, etc. can be considered.

  The surface shape shaping method can be easily processed into a smooth surface with a squeegee or a press.

  For curing the smooth layer 8, a curing method corresponding to the material of the smooth layer 8 such as drying, cooling, and ultraviolet irradiation is selected.

  Below, the formation method in the case of using the thermosoftening resin containing a rosin acid as the smooth layer 8 is demonstrated.

  As shown in FIG. 1, an adhesive 3 is applied to a fixing jig 2, and the hard brittle substrate 1 is bonded and fixed. Next, as shown in FIG. 2, the smooth layer agent 10 is put in a dip bowl 9 and heated to a temperature at which the smooth layer agent 10 is liquefied. Thereafter, the surface side of the hard brittle substrate 1 bonded to the fixing jig 2 is dipped in a dip bowl 9, and the smooth layer 10 is applied and taken out.

  Thereafter, as shown in FIG. 3, the surface of the smooth layer 8 is smoothed by removing an excess amount with a squeegee 11. Then it is cooled and cured. At this time, the maximum height Ry of the surface of the smooth layer 8 is set to be 1/3 or less of the thickness of the blade 4.

  Next, the cutting process will be described.

  As shown in FIG. 4, the workpiece on which the smooth layer 8 is formed is fixed to the table of the dicing machine with a vacuum chuck, and, for example, the φ4 ″ × 0.3 mmt blade 4 is moved in the X direction while rotating so that the cutting groove is formed. The material of the blade 4 is preferably a resin bond, a metal bond, or a resin metal bond using diamond abrasive grains, and the thickness of the blade 4 is preferably 0.3 to 0.7 mm. After passing the object, the blade position is returned to the origin, the Z-axis is lowered and the cutting groove is processed again, the Z-axis is lowered and the substrate is completely cut in the same manner five times, and the substrate is divided, and the workpiece is peeled off from the fixing jig. If the peeled workpiece is washed with a warmed alkaline detergent and the smooth layer 8 is removed, a substrate free from chipping and cracking can be produced. To implement the polishing.

  The rigidity of the blade 4 greatly depends on the thickness of the blade 4. By making the maximum height Ry of the smooth layer 8 surface 1/3 or less of the thickness of the blade 4 and making the smooth layer 8 a hardness of Shore hardness 30 or more, the effect of preventing the inclination of the blade 4 and the cutting of the unevenness 7 The effect of dispersing stress can be obtained. When the hardness is low, the effect of suppressing the vibration of the blade 4 cannot be obtained.

  The thickness of the smooth layer 8 may be any thickness that can achieve the maximum height Ry of the predetermined surface, but is preferably 0.04 mm or more in order to obtain the effect of suppressing the vibration of the blade 4. If a material having higher hardness is used as the smooth layer 8, the film 4 can be thinned because the effect of vertically holding the blade 4 with respect to the hard brittle substrate 1 is high.

  Since the formation of the smooth layer 8 is simple and desirable, dipping and brush application are preferable, and the flow viscosity at the time of formation is preferably 300 cp or more in order to easily obtain a smooth surface. If the viscosity is low, it will flow down from the substrate during formation, making it difficult to ensure a sufficient film thickness.

  As the material of the smooth layer 8, since dipping, spraying, and application are simple and desirable, it is liquefied at the time of formation, and is a vinyl compound, petroleum resin, which is cured to a certain degree by heat curing, cooling curing or ultraviolet curing. Natural resins such as rosin and their derivatives are desirable.

  Depending on the material and film thickness of the smooth layer 8, there is a possibility that clogging of the side surface of the blade grindstone 6 occurs during cutting. In this case, clogging can be avoided by containing fine abrasive grains in the material of the smooth layer 8, and stable cutting can be carried out continuously. As the kind of abrasive grains to be contained, silicon carbide abrasive grains (GC) or white alumina abrasive grains (WA) are preferable when the blade 4 is a diamond specification, and the particle diameter is equal to or smaller than the abrasive grain diameter of the blade 4 to be used. Things are desirable. The content is preferably about 3% to 30% because too much content leads to an increase in cutting resistance.

  When the smooth layer 8 is made of the same material as the adhesive 3 for bonding the substrate to the fixing jig, the cleaning process is simplified because the smooth layer 8 and the adhesive 3 can be cleaned with the same detergent after cleaning. Benefits that can be expected. Moreover, since the smooth layer 8 can be formed by dipping, the formation process of the smooth layer 8 can be easily constructed.

(Example 1)
Prepare a sapphire substrate with projections with a thickness of 1.5 mm and a maximum height Ry of 0.13 mm, and prepare several thermosoftening resins with different shear hardnesses to form the smooth layer 8 And it was set as the sample for evaluation.

  Here, the shaping method of the smooth layer 8 is as follows. First, the sapphire substrate is heated to 120 ° C., and the thermosoftening resin is applied to the surface of the sapphire substrate with a thickness of 0.2 mm. It was formed by smoothening the surface of the softening resin and then cooling to room temperature and curing.

  Here, the maximum height Ry and the shear hardness of the surface of the obtained smooth layer 8 are as shown in Table 1.

  The sample for evaluation thus obtained was bonded to the fixing jig 2 and cut at a speed of 4 mm / s with a dicing apparatus of 1.5 kW air spindle specification. Here, the blade 4 had a thickness of 0.3 mm, and used a resin bond containing # 270 diamond abrasive grains in a resin bond.

  A sapphire substrate (thickness 1.5 mm, maximum surface height Ry 0.13 mm) on which the smooth layer 8 is not formed is also the sample No. 5 was cut in the same manner.

Table 1 shows the occurrence rate of chipping in the sapphire substrate after cutting, and the maximum value of cutting resistance. The number of samples in each sample was 100, and chipping defects were targeted for widths and depths of 50 μm or more.

  As is clear from Table 1, sample No. In 1 and 2, defects due to chipping could be suppressed. This is because the maximum height Ry of the surface of the smooth layer 8 is 1/3 or less of the thickness of the blade 4 and the shear hardness of the smooth layer 8 is 30 or more. This is considered to disperse the cutting stress of the convex part 8.

  In contrast, sample no. In No. 3, since the shear hardness of the smooth layer 8 was 27, the deflection of the blade 4 could not be prevented and chipping failure occurred. Sample No. 4, although the shear hardness of the smooth layer 8 is 30 or more, the maximum height Ry of the surface of the smooth layer 8 is 0.12 mm, which is 1/3 or more of the thickness of the blade 4, so chipping failure There has occurred.

  Furthermore, sample No. in which the smooth layer 8 is not formed. No. 5 had a high chipping defect rate because the blade 4 was not tilted and the cutting stress was not dispersed.

(Example 2)
Furthermore, sample No. 1 in Example 1 was used. 1, sample no. 5 was used to evaluate the change in cutting resistance during cutting. The cutting conditions were the same as in Example 1.

  Sample No. 1 is shown in FIG. The result of 5 is shown in FIG.

  Sample No. 5 in which the smooth layer 8 is formed. In No. 1, even when the blade 4 is approaching the substrate convex portion, the grinding stone portion 6 of the blade 4 is held by the smooth layer 8, so that no inclination occurs, so that the cutting resistance value is stable without a large fluctuation.

  On the other hand, Sample No. in which the smooth layer 8 is not formed. In No. 5, the cutting resistance value increases when the blade 4 approaches the convex portion, and it can be seen that a load is applied to the blade 4 and the sapphire substrate, which is also considered to be a chipping failure.

  The present invention provides a substrate cutting method for continuously and suitably cutting a hard brittle substrate having fine irregularities with high accuracy and high quality.

It is a figure for demonstrating the fixing jig sticking state in the cutting method of the hard brittle board | substrate of this invention. It is a figure for demonstrating the state of the dipping in the cutting method of the hard brittle board | substrate of this invention. It is a figure for demonstrating the smooth layer surface shaping in the cutting method of the hard brittle board | substrate of this invention. It is a figure for demonstrating the cutting process in the cutting method of the hard brittle board | substrate of this invention. It is a graph which shows the relationship between the surface state and cutting resistance value in the Example of this invention. It is a graph which shows the relationship between the surface shape of a comparative example, and a cutting resistance value. It is a figure which shows the conventional cutting method. It is an enlarged view which shows the conventional cutting method.

Explanation of symbols

1: Hard brittle substrate 2: Fixing jig 3: Adhesive 4: Blade 5: Blade base 6: Blade grindstone 7: Concavity and convexity 8: Smooth layer 9: Dip pad 10: Smooth layer 11: Squeegee

Claims (5)

In a substrate cutting method in which a hard brittle substrate having fine irregularities on a surface is cut with a disk-shaped rotary blade, a smooth layer made of a material having a Shore hardness of 30 or more is formed on the irregularities, and the maximum surface of the smooth layer is formed. A cutting method of a hard brittle substrate, wherein the height Ry is set to 1/3 or less of the thickness of the rotating blade, and the smooth layer and the hard brittle substrate are cut together. The method for cutting a hard brittle substrate according to claim 1, wherein a flow viscosity at the time of forming the smooth layer is 300 cp or more. 2. The method for cutting a hard brittle substrate according to claim 1, wherein the material of the smooth layer is at least one of natural resins such as vinyl compounds, petroleum resins, rosin, and derivatives thereof. The method for cutting a hard brittle substrate according to claim 1, wherein the smooth layer contains fine abrasive grains. The method for cutting a hard brittle substrate according to claim 1, wherein the substrate is bonded to a fixing jig using an adhesive made of the same material as the smooth layer.

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