TWI410293B - Method of flattening volcano crater edges formed by laser - Google Patents

Abstract

A method of flattening volcano crater edges formed by laser includes a step of providing a substrate, a step of processing a laser-carving step on a surface of the substrate to form at least one micro notch with at least one protrusion at the periphery of the micro notch, and a step of removing the protrusion of the micro notch so as to reduce the height of the protrusion after the laser-carving step.

Description

Laser processing method for crater processing

The invention relates to a method for leveling a laser processing crater.

Conventionally, when a high-temperature bombardment of a substrate surface by a laser beam is used to form a recessed hole, the slag splashing phenomenon of the substrate is inevitably caused, so that the appearance of a volcano crater is formed at each recessed hole. That is, one or more irregular protrusions are formed on the periphery of the concave hole. Such protrusions impose an inconvenient burden on the subsequent use of the substrate.

For example, when optical micro-structures are conventionally fabricated on the surface of a light guide plate, a plurality of micro-recessed holes are formed in the stamping die by using a laser beam to print on the surface of the light guide plate by using the micro-recess holes on the surface of the stamping die. The corresponding optical microstructure is extruded.

However, when the stamping die presses the light guide plate a plurality of times, so that the protrusion of the periphery of the micro recessed hole is bent or collapsed and falls into the micro recessed hole to fill the micro recessed hole, the stamping die cannot be completed. The ground prints out a complete optical microstructure pattern, which in turn leads to deterioration of the light guiding performance of the light guide plate.

It can be seen that the structure of the above-mentioned printing die still has inconvenience and defects, and needs to be further improved. In order to solve the above problems, the relevant fields have not exhausted their efforts to seek solutions, but the methods that have not been applied for a long time have been developed.

Therefore, how to provide a structure that effectively solves the above problems and avoid reappearing the above-mentioned consequences is one of the current important research and development topics, and has become an urgent need for improvement in related fields.

The invention discloses a method for leveling a laser processing crater for providing a substrate with a plurality of micro recesses.

The invention discloses a method for leveling a laser processing crater, which is used for reducing the chance of the protrusion of the periphery of the micro concave hole filling the micro concave hole due to falling off.

The invention discloses a method for leveling a laser processing crater. The method comprises the steps of providing a substrate, performing laser processing on the surface of the substrate such that the surface of the substrate forms at least one micro-recessed hole, wherein the opening of the micro-recessed hole has at least one protrusion and laser processing After completion, the protrusions on the periphery of the micro-recess opening are removed, so that the periphery of the micro-recess is flattened.

In a first embodiment of the present invention, the step of removing the protrusions around the periphery of the micro-recess holes may include the step of cutting the protrusions around the periphery of the micro-recess holes by the cutter. In one variation of this first embodiment, only the protrusions of the periphery of the micro-recess holes on the surface of the substrate are cut by the cutter in the direction parallel to the surface of the substrate. In another variation of this first embodiment, the surface of the substrate is removed by a cutter in a direction parallel to the surface of the substrate to cut off the surface of the substrate comprising protrusions around the periphery of the microrecess. The thickness of the surface of the cutting substrate of the cutter ranges from 1 micrometer to 5 micrometers. Moreover, the tool in this first embodiment is a diamond knife or a carbon fiber knife.

In a second embodiment of the present invention, the step of removing the protrusions around the periphery of the micro-recess holes may include the steps of etching the protrusions around the periphery of each of the micro-recess holes by an acidic solution, so as to eliminate the protrusions on the periphery of each of the micro-recess holes. The substrate is a metal module. Specifically, the step of etching the protrusions around the periphery of each of the micro-recess holes by the acidic solution further comprises the step of immersing the substrate in a monophosphoric acid solution, wherein the concentration of the phosphoric acid solution is 10%.

In a third embodiment of the present invention, the step of removing the protrusions around the periphery of the micro-recess holes may include the step of ejecting the high-pressure sand particles to strike the surface of the substrate. In this third embodiment, the high pressure sand is glass sand, corundum, white sand or red sand. In this third embodiment, the high speed grit travels at a speed of 15-30 meters per minute. In this third embodiment, the pressure of the high pressure grit is 0.003 - 0.3 MPa (MPA).

In a fourth embodiment of the present invention, the step of removing the protrusions around the periphery of the micro-recess may include the step of grinding the surface of the substrate by an abrasive tool.

In a fifth embodiment of the present invention, the step of removing the protrusions around the periphery of the micro-recess holes may include the steps of bonding the surface of the substrate by a pressing tool and starting the pressing tool along the surface of a vertical substrate. The direction presses the surface of the substrate so as to collapse the protrusions around the periphery of each of the micro-recess holes.

In summary, the method for leveling the laser processing crater of the present invention can reduce or even avoid the opportunity for the protrusions around the periphery of the micro-recess to fill the micro-recessed holes, thereby avoiding the substrate, for example, after the light guide plate is manufactured. , causing deterioration of its light guiding performance; or when the substrate, for example, a metal stamping die, is subjected to the printing operation of the optical microstructure pattern of the light guide plate, the correct optical microstructure cannot be printed on the surface of the light guide plate. The pattern, and further, also increases the product life of the stamping die.

The present invention will be apparent from the following description and the detailed description of the embodiments of the present invention, which may be modified and modified by the teachings of the present invention without departing from the invention. The spirit and scope.

As described above, in view of the high-temperature irradiation of the surface of the substrate by the laser beam, the slag splash phenomenon is inevitably caused, so that the appearance of the crater at each of the micro-recess holes will result in a projection of the periphery of the crater. It may fall into the micro-recessed hole, which may hinder the work of the subsequent substrate or affect the optical performance of the light guide plate.

To this end, please refer to FIGS. 1 to 3, and FIG. 1 is a flow chart showing a method for leveling the laser processing crater of the present invention. 2 is a partial enlarged view of a substrate of the present invention and a micro-recess 210 therein. Fig. 3 is a cross-sectional view taken along line 3-3 of Fig. 2.

The invention provides a method for leveling a laser processing crater, the step comprising: step (101) providing a substrate 100.

In this step, the substrate 100 has a plate shape and may be, for example, a metal mold, a diffusion film or a light guide plate. Metal molds, such as stamping dies, can be made of stainless steel, copper, iron or aluminum. The light guide plate is made of, for example, a transparent material such as polyethylene terephthalate (PET), polycarbonate (PC), or poly(methyl methacrylate) (PMMA).

Step (102) performs laser processing on the surface 110 of the substrate 100 such that the surface 110 of the substrate 100 forms one or more micro-recesses 210 having a crater shape, wherein each of the micro-recessed holes 210 has an opening circumference or A plurality of protrusions 220 (Fig. 3). Since the diameter of the recessed holes has a micron size, it is called a micro recess 210.

For example, this step is based on a pattern design in which a plurality of laser beams are respectively outputted to the surface 110 of the substrate 100 by the laser generator, so that the laser beams respectively bombard the surface 110 of the substrate 100 to melt a plurality of miniatures. The recessed holes 210 (Fig. 2), the micro recessed holes 210 form a microporous pattern 200 on the surface 110 of the substrate 100.

Step (103), after the laser processing is completed, the outer edge of the crater of each of the micro recesses 210 is removed.

In this step, after the laser processing process is completed, the protrusions 220 of the peripheral edges of the micro-recess holes 210 are physically or chemically removed, so as to eliminate the outer edges of the craters of the micro-recess holes 210; The protrusions 220 of the periphery of the micro-recess holes 210 are so as to flatten the circumference of each of the micro-recess holes 210, even if the periphery of the opening of each of the micro-recess holes 210 is substantially flush with the surface 110 of the substrate 100.

In addition, when the substrate 100 is the metal mold 130 and after completing the flattening method of the laser processing crater of the present invention, one of the applications can utilize the above-mentioned micropore collection pattern 200 for printing out the surface of a light guide plate. An optical structure pattern. When the substrate 100 is a light guide plate and after completing the flattening method of the laser processing crater of the present invention, it can be mounted into a backlight module to provide light guiding performance.

Further embodiments of the present invention are further disclosed below to further clarify various methods of the flattening method of the laser processing crater of the present invention.

Please refer to FIG. 4 and FIG. 5A. FIG. 4 is a detailed flow chart of step 103 of FIG. 1 in a first embodiment. Fig. 5A is a schematic view (I) of the operation of the first embodiment of the present invention.

When the substrate 100 of the first embodiment can be a light guide plate, a metal mold or a diffusion film, the step (103A ₁ ) and the step (103A ₂ ) can be specifically included in the step 103 as follows.

Step (103 A ₁ ): cutting out the protrusions 220 on the periphery of the micro recess 210.

In this step, in the first embodiment, only the protrusions 220 on the periphery of each of the micro-recess holes 210 can be cut by the cutter 300.

This step is changed in one of the first embodiments (Fig. 5A), which means that the cutter 300 slides on the surface 110 of the substrate 100 along the direction R ₁ of the surface 110 of the parallel substrate 100, and only scrapes each The protrusions 220 on the periphery of the micro-recess 210 do not damage the surface 110 of the substrate 100; preferably, this step allows the periphery of the micro-recess 210 and the surface of the substrate 100 to be changed in one of the first embodiments. 110 is roughly flush.

Step (103 A ₂ ): The substrate 100 is washed.

In this step, the surface 110 of the substrate 100 is washed by the cleaning liquid so that the protrusions 220, particles or chips that have been detached from the substrate 100 can be separated from the substrate 100 with the cleaning liquid. The cleaning procedure can be, for example, ultrasonic cleaning. The cleaning liquid may be, for example, pure water, alcohol or isopropyl alcohol (IPA) or the like.

In addition, referring to FIG. 5B, FIG. 5B is a schematic view (II) of the operation of the first embodiment of the present invention. The above step (103 A ₁ ) is another variation (Fig. 5B), which means that the outer layer L of one surface 110 of the substrate 100 is removed by the cutter 300 in the direction R ₁ parallel to the surface 110 of the substrate 100. The cutters may sequentially pass through the respective micro-recess holes 210 to collectively remove the protrusions 220 of the surface 110 of the substrate 100 including the periphery of each of the micro-recess holes 210; preferably, the other variation may make the micro-concave The perimeter of the aperture 210 is substantially flush with a new surface 120 of the substrate 100.

Specifically, in this other variation, the cutter 300 cuts the outer layer L of the substrate 100 to a thickness ranging from approximately 1 micrometer to 5 micrometers. In addition, the cutter 300 may be a fly cutter that rotates the surface 110 of the substrate 100 or protrudes from the surface 110 of the substrate 100 by taking the direction of the surface 110 of the vertical substrate 100 as a shaft. Object (projection 220). In addition, the cutter 300 described above is made of diamond or carbon fiber and is a diamond knife or a carbon fiber knife.

Please refer to FIG. 6 and FIG. 7. FIG. 6 is a detailed flow chart of step 103 of FIG. 1 in a second embodiment. Figure 7 is a schematic view showing the operation of the second embodiment of the present invention.

When the substrate 100 of the second embodiment can be the metal mold 130, the step (103B ₁ ) and the step (103B ₂ ) can be specifically included in the step 103 as follows.

Step (103B ₁ ): the protrusions 220 on the periphery of each of the micro-recess holes 210 are eroded by an acidic solution 400 so that the protrusions 220 on the periphery of each of the micro-recess holes 210 are eliminated.

In this step, in the second embodiment, the metal mold 130 can be immersed in a container 410 having an acidic solution 400, so that the protrusions 220 on the periphery of each of the micro-recess holes 210 of the surface 110 of the metal mold 130 are gradually eroded. Not so prominent. Preferably, this step allows the circumference of the micro-recess 210 to be substantially flush with the surface 110 of the metal mold 130 in the second embodiment.

For example, the acidic solution 400 is, for example, a monophosphoric acid solution, and the concentration of the phosphoric acid solution is 10%. After the metal mold 130 is immersed in the phosphoric acid solution for 30 minutes, the protrusions 220 on the periphery of each of the micro-recess holes 210 are gradually subjected to a phosphoric acid solution. The corrosion gradually dissolves in the acidic solution 400, and is further separated from the surface of the metal mold 130 (i.e., the periphery of each of the micro recesses 210). However, although the phosphoric acid blending solution used in the above example, the operator may vary depending on the type of the metal mold material (e.g., nickel plating, aluminum, copper, etc.).

It should be noted that, due to the setting of acidity and alkalinity (pH value), concentration and time, only the protrusions 220 of the periphery of each of the micro-recess holes 210 can be controlled to be substantially separated from the surface of the metal mold 130 (ie, each micro The periphery of the recess 210 does not cause too much damage to the surface of the metal mold 130 or the inner walls of the micro recess 210.

Moreover, the operator can select an appropriately set acidic solution 400 according to different materials of the metal mold 130 to remove the protrusions 220 on the periphery of each of the micro recesses 210.

Step (103 B ₂ ): cleaning the metal mold 130.

In this step, the surface 110 of the metal mold 130 is washed by the cleaning liquid, so that the protrusions 220, particles, chips and the acidic solution 400 which have been detached from the metal mold 130 can be separated from the metal mold 130 with the cleaning liquid. The cleaning procedure can be, for example, ultrasonic cleaning. The cleaning liquid may be, for example, pure water, alcohol or isopropyl alcohol (IPA) or the like.

Please refer to FIG. 8 and FIG. 9. FIG. 8 is a detailed flow chart of step 103 of FIG. 1 in a third embodiment. Figure 9 is a schematic view showing the operation of the third embodiment of the present invention.

When the substrate 100 of the third embodiment can be a light guide plate, a metal mold or a diffusion film, the step (103C ₁ ) and the step (103C ₂ ) can be specifically included in the step 103 as follows.

Step (103C ₁ ): The high-pressure sand particles 510 are sprayed to strike the surface of the substrate 100, thereby flattening the protrusions 220 on the periphery of each of the micro-recess holes 210.

In the third embodiment, the high pressure grit 510 ejected by the blasting tool 500 strikes the protrusions 220 on the periphery of each of the micro recesses 210 of the surface 110 of the substrate 100. Thus, the surface 110 of the substrate 100 The protrusions 220 on the periphery of each of the micro-recess holes 210 can be impacted and flattened without being so protruded. Preferably, this step allows the periphery of the micro-recess 210 to be substantially flush with the surface 110 of the substrate 100 in the third embodiment.

For example, the grit may be, for example, glass sand, silicon carbide, white sand or red sand, and the like. The traveling speed of the high pressure grit 510 may be, for example, 15 to 30 meters per minute. The pressure of the high pressure grit 510 can be, for example, 0.003-0.3 megapascals (MPA).

It should be noted that when the high-pressure sand 510 is sprayed on the surface 110 of the substrate 100, the surface of the substrate 100 may be convexly granulated. Step (103 C ₂ ): The substrate 100 is washed.

In this step, the surface 110 of the substrate 100 is rinsed with a cleaning solution such that the detached protrusions 220, particles, chips or residual high pressure grit 510 on the substrate 100 can be separated from the substrate 100 with the cleaning solution. The cleaning procedure can be, for example, ultrasonic cleaning. The cleaning liquid may be, for example, pure water, alcohol or isopropyl alcohol (IPA) or the like.

Thus, when the substrate 100 is applied to the light guide plate in this embodiment, the surface of the light guide plate exhibits a convex grain shape to provide an atomization process for homogenizing the light to be transmitted. Similarly, when the substrate 100 is applied to the metal mold in this embodiment, the surface of the light guide plate can be printed with an optical structure pattern, wherein the surface of the metal mold surface 110 is convex and the surface of the light guide plate can be made. An atomization process is formed.

In addition, the operator can select a suitable blasting tool 500 according to the degree of protrusion of the protrusions 220 on the periphery of each of the micro-recess holes 210 to surely flatten the protrusions 220 of the periphery of each of the micro-recess holes 210.

Please refer to FIG. 10 and FIG. 11 . FIG. 10 is a detailed flow chart of step 103 of FIG. 1 in a fourth embodiment. Figure 11 is a schematic view showing the operation of the fourth embodiment of the present invention.

The substrate 100 of the fourth embodiment can be applied to a light guide plate, a metal mold or a diffusion film. Specifically, in step 103, the step (103D ₁ ) and the step (103D ₂ ) can be specifically included as follows.

Step (103 D ₁ ): grinding the surface of the substrate 100 to remove the protrusions 220 of the periphery of each of the micro-recess holes 210.

In this step, in the fourth embodiment, the protrusions 220 on the periphery of each of the micro recesses 210 can be removed by a grinding tool 600, such as a grinder; preferably, this step can be performed in the fourth embodiment. The periphery of the micro-recess 210 is substantially flush with the surface 110 of the substrate 100.

Step (103 D ₂ ): The substrate 100 is washed.

In this step, the surface 110 of the substrate 100 is washed by the cleaning liquid so that the protrusions 220, particles or chips that have been detached from the substrate 100 can be separated from the substrate 100 with the cleaning liquid. The cleaning procedure can be, for example, ultrasonic cleaning. The cleaning liquid may be, for example, pure water, alcohol or isopropyl alcohol (IPA) or the like.

As such, when the substrate 100 is applied to the light guide plate in this embodiment, the surface of the light guide plate is ground to provide an atomization process for homogenizing the transmitted light.

Referring to FIG. 12 and FIG. 13, FIG. 12 is a detailed flow chart of step 103 of FIG. 1 in a fifth embodiment. Figure 13 is a schematic view showing the operation of the fifth embodiment of the present invention.

The substrate 100 of the fourth embodiment can be applied to a light guide plate, a metal mold or a diffusion film. Specifically, in step 103, the step (103E ₁ ) and the step (103E ₂ ) can be specifically included as follows.

Step (103 E ₁ ): the protrusions 220 on the periphery of the micro-recess 210 of the substrate 100 are flattened by a pressing tool 700.

In this step, in the fifth embodiment, the protrusions 220 on the periphery of each of the micro-recess holes 210 are flattened by a pressing tool 700, so that the protrusions 220 on the periphery of each of the micro-recess holes 210 are not so protruded.

Specifically, the fifth embodiment can be first attached to the surface of the substrate 100 having the micro recess 210 by a pressing tool 700 (FIG. 13(a)), and then the pressing tool 700 is placed along a vertical substrate. The direction R ₂ of the surface of 100 begins to press the surface of the substrate 100 such that the protrusions 220 of the periphery of the micro-recess 210 are flattened (Fig. 13(b)); preferably, this step is in the fifth embodiment. The periphery of the micro-recess 210 may be substantially flush with the surface 110 of the substrate 100.

Step (103 E ₂ ): The substrate 100 is washed.

In this step, the surface 110 of the substrate 100 is washed by the cleaning liquid so that the protrusions 220, particles or chips that have been detached from the substrate 100 can be separated from the substrate 100 with the cleaning liquid. The cleaning procedure can be, for example, ultrasonic cleaning. The cleaning liquid may be, for example, pure water, alcohol or isopropyl alcohol (IPA) or the like.

In summary, since the above embodiments can force the protrusions 220 of the periphery of each micro-recess 210 to be not so protruded, the method for leveling the laser processing crater of the present invention can reduce or even avoid the periphery of the micro-recess 210. The protrusion 220 fills the micro-recess 210 by falling off, thereby preventing the substrate 100, for example, after the light guide is completed, causing deterioration of its light guiding performance; or the substrate 100, for example, a metal stamping die When the light guide plate performs the printing operation of the optical microstructure pattern, the correct optical microstructure pattern cannot be printed on the surface of the light guide plate, and further, the product life of the stamping mold is also improved.

The present invention is not limited to the embodiments of the present invention, and various modifications and refinements may be made without departing from the spirit and scope of the present invention. This is subject to the definition of the scope of the patent application.

100. . . Substrate

110. . . surface

120. . . New surface

130. . . Metal mold

200. . . Micropore aggregation pattern

210. . . Miniature recess

220. . . Protrusion

300. . . Tool

400. . . Acid solution

410. . . container

500. . . Sandblasting tool

510. . . High pressure sand

600. . . Grinding tool

700. . . Compression tool

L. . . Outer layer

R ₁ , R ₂ . . . direction

101-103. . . step

103A ₁ -103A ₂ . . . step

103B ₁ -103B ₂ . . . step

103C ₁ -103C ₂ . . . step

103D ₁ -103D ₂ . . . step

103E ₁ -103E ₂ . . . step

The above and other objects, features, advantages and embodiments of the present invention will become more apparent and understood.

FIG. 1 is a flow chart showing a method for leveling a laser processing crater of the present invention.

2 is a partial enlarged view of a substrate according to an embodiment of the present invention and a micro-recessed hole therein.

Fig. 3 is a cross-sectional view taken along line 3-3 of Fig. 2.

FIG. 4 is a detailed flow chart of step 103 of FIG. 1 in a first embodiment.

Fig. 5A is a schematic view (I) of the operation of the first embodiment of the present invention.

Fig. 5B is a schematic view (II) showing the operation of the first embodiment of the present invention.

FIG. 6 is a detailed flow chart of step 103 of FIG. 1 in a second embodiment.

Figure 7 is a schematic view showing the operation of the second embodiment of the present invention.

FIG. 8 is a detailed flow chart of step 103 of FIG. 1 in a third embodiment.

Figure 9 is a schematic view showing the operation of the third embodiment of the present invention.

FIG. 10 is a detailed flow chart of step 103 of FIG. 1 in a fourth embodiment.

Figure 11 is a schematic view showing the operation of the fourth embodiment of the present invention.

Figure 12 is a flow chart showing the details of step 103 of Figure 1 in a fifth embodiment.

Figure 13 is a schematic view showing the operation of the fifth embodiment of the present invention.

101-103. . . step

Claims (12)

A method for leveling a laser processing crater, which is suitable for fabricating an optical microstructure pattern, the method comprising: providing a substrate, wherein the substrate is a light guide plate or a diffusion film; One of the outer surfaces of the material is subjected to laser processing such that the outer surface of the substrate forms a plurality of micro-recessed holes, wherein each of the micro-recessed holes has at least one protrusion at the periphery of the opening; and after the laser processing is completed, The protrusions of the periphery of each of the micro-recess openings are removed such that the periphery of the micro-recess holes is planarized such that the micro-recess holes form the optical microstructure pattern. The method for leveling a laser processing crater according to claim 1, wherein the step of removing the protrusion of each of the micro-recess holes comprises: cutting the protrusion of the periphery of the micro-recess by a cutter Providing the tool in a direction parallel to the outer surface of the substrate, the outer surface of the substrate being cut to a thickness ranging from 1 micrometer to 5 micrometers, to remove the outer surface of the substrate comprising the micro recess The protrusion of the circumference. The method for leveling a laser processing crater according to claim 1, wherein the step of removing the protrusion of each of the micro-recess holes comprises: spraying high-pressure sand particles to strike a surface of the substrate, wherein the high voltage The sand is glass sand, corundum, white sand or red sand. The method for leveling a laser processing crater according to claim 3, wherein the high pressure sand has a traveling speed of 15-30 meters/minute, and the high pressure sand The pressure of the granules is from 0.003 MPa (MPA) to 0.3 MPa (MPA). The method for leveling a laser processing crater according to claim 1, wherein the step of removing the protrusion of each of the micro-recess holes comprises: grinding the outer surface of the substrate by an abrasive tool. A method for leveling a laser processing crater, which is suitable for fabricating an optical microstructure pattern, the method comprising: providing a substrate, wherein the substrate is a stamping die; according to a pattern design, one of the substrates is outside The surface is subjected to laser processing such that the outer surface of the substrate forms a plurality of micro-recessed holes, wherein each of the micro-recessed holes has at least one protrusion on the periphery of the opening; and after the laser processing is completed, each is removed The protrusions of the periphery of the micro-recess openings open the periphery of the micro-recess holes, and the micro-recess holes of the stamping die are used to print the optical microstructure pattern on the outer surface of a light guide plate. . The method for leveling a laser processing crater according to claim 6, wherein the step of removing the protrusion of each of the micro-recess holes comprises: cutting the protrusion of the periphery of the micro-recess by a cutter Providing the tool in a direction parallel to the outer surface of the substrate, the outer surface of the substrate being cut to a thickness ranging from 1 micrometer to 5 micrometers, to remove the outer surface of the substrate comprising the micro recess The protrusion of the circumference. a method for leveling a laser processing crater as described in claim 6 The step of removing the protrusions on the periphery of each of the micro-recess holes comprises: etching the protrusions on the periphery of the micro-recess holes by an acidic solution, wherein the substrate is immersed in a phosphoric acid solution, wherein The concentration of the phosphoric acid solution was 10%. The method for leveling a laser processing crater according to claim 6, wherein the step of removing the protrusion of each of the micro-recess holes comprises: spraying high-pressure sand particles to strike a surface of the substrate, wherein the high voltage The sand is glass sand, corundum, white sand or red sand. The method for leveling a laser processing crater according to claim 9, wherein the high pressure sand has a traveling speed of 15 to 30 meters per minute, and wherein the pressure of the high pressure sand is 0.003 to 0.3 megapascals (MPA). The method for leveling a laser processing crater according to claim 6, wherein the step of removing the protrusion of each of the micro-recess holes comprises: grinding the outer surface of the substrate by an abrasive tool. The method for leveling a laser processing crater according to claim 6, wherein the step of removing the protrusion of each of the micro-recess holes comprises: attaching the substrate to the substrate by a pressing tool a surface; and causing the compression tool to begin pressing the outer surface of the substrate in a direction perpendicular to the outer surface of the substrate such that the protrusion of the periphery of the micro-recess is flattened.