KR101680268B1

KR101680268B1 - Laser separating method along a closed shaped penetrated part from brittle substrate

Info

Publication number: KR101680268B1
Application number: KR1020150040543A
Authority: KR
Inventors: 이진하
Original assignee: 주식회사 고려반도체시스템
Priority date: 2015-03-24
Filing date: 2015-03-24
Publication date: 2016-11-28
Also published as: KR20160114296A

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method for acquiring a closed curve shape such as a circle or a square in a transparent and transparent material such as sapphire and glass, A separation step of isolating a first portion surrounded by the closed curve from the substrate by irradiating a first laser beam along the closed curve to form a penetrating line through the closed curve; And a drilling step of irradiating a second laser beam into the first part held in the substrate while being separated from the substrate by the penetrating line to break the inside of the first part, There is provided a laser processing method capable of omitting a subsequent process because cracks and chipping are hardly generated in the cross section and the processed cross section is processed almost vertically without being tapered.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a laser machining method for forming a through-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a processing method for acquiring a closed curve shape such as a circle or a square in a transparent and transparent material such as sapphire and glass and more particularly to a processing method in which cracks and chipping The present invention relates to a processing method for obtaining a shape of a closed curve of a brittle material which can be omitted in a subsequent process because the processed section is processed almost vertically without being tapered.

Laser processing is the most generalized and stabilized process in high-energy optical processing technology using integrated photons. Laser processing refers to the removal of material while melting and evaporating the material using the high energy of the laser, which is also called ablation processing.

By disassembling the direct molecular bonds in the laser beam with a short wavelength and a very short pulse width, it is possible to remove the material in the atomic state without thermal effect, and uniform and precise processing is possible.

Since the development of the optical part of the laser beam can finely focus the laser beam to 100 μm or less, it is possible to perform fine processing by the non-contact method without deformation and contamination of the material.

In addition, it is possible to process in the air, and it is possible to process a structure of about 200nm in size when direct processing or indirect processing of several micrometer size structure is used, and when using an optical instrument such as a precision scanner, high speed processing is possible, Micrometer-scale structural processing is the only realistic technology available.

These lasers are used to cut transparent materials such as sapphire and glass, and to process transparent materials (holes), such as circular or quadrilateral, through lasers.

Conventionally, in the laser processing in the form of a closed curve on a flat plate of brittle material such as sapphire or glass, as shown in FIG. 1, a transparent and flat transparent material 10, such as sapphire or glass, Likewise, it is processed so as to obtain a closed curve shape such as a circle or a square.

As shown in FIG. 2, when a laser beam is incident on a workpiece, the laser beam is absorbed by the workpiece to cause a local temperature rise. As a result, the laser beam is softened and melted Abraded and removed.

In this process, as shown in FIG. 2, a subsequent process is required because fine cracks are generated in a portion of the workpiece where the laser is incident, a thermally deformable layer is formed, a re-coat layer is formed on the processed surface,

As shown in Fig. 3, chipping of 30 to 300 mu m is generated around the machined surface of the workpiece, and taper phenomena of 80 to 150 mu m are generated on the machined surface of the workpiece as shown in Fig. Since the portion of the tapered portion which is projected with the tapered portion is significantly low in impact resistance, a subsequent process for removing the tapered portion is required, which complicates the process and raises the processing cost.

Literature 1. Korea Patent Application Publication No. 10-2010-0017336, "Numerous laser wavelength and pulse width process hole drilling ". Document 2: Korean Patent Registration No. 10-0561763 entitled "Method for cutting components such as glass, ceramics and glass ceramics by generating a thermal expansion gap on a component along a cutting region".

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a processing method in which transparent and flat materials such as sapphire and glass are obtained in the form of a closed curve such as a circle or a square.

That is, according to the present invention, since cracks and chipping rarely occur in a processing region of a substrate formed of a brittle material, and a processed section is processed almost vertically without tapering, a subsequent process can be omitted, Shaped through-holes in the form of a brittle material capable of reducing the size of the brittle material.

In order to achieve the above object, the present invention provides a method for forming a through-hole in the form of a closed curve on a substrate made of a brittle material, the method comprising: forming a through line passing through the closed curve by irradiating a first laser beam along the closed curve; A separation step of isolating a first portion surrounded by the closed curve from the substrate; And a drilling step of irradiating a second laser beam inside the first part held in the substrate while being separated from the substrate by the penetrating line to crush the inside of the first part. A laser processing method is provided.

This is because the first laser beam is irradiated along the closed curve to form a through line that penetrates the substrate with a fine thickness through a path in the form of a predetermined closed curve and then the substrate is thermally expanded by laser processing despite the thin through- The second laser beam is irradiated to the inside of the first portion which is sandwiched and the second portion is broken so that the first portion and the substrate can be pinched by the broken portion and the first portion can be easily removed So as to form a through-hole in the form of a closed curve from the substrate along the through-line with an accurate vertical cross-section.

This makes it possible to prevent the occurrence of cracks in the processing region during the process of forming the through holes such as the speaker, the home button, and the microphone on the protective substrate or the display substrate of the display device or the mobile device, ) Phenomenon can be suppressed and an effect that the section of the through hole can be accurately formed within a short time in a clean and almost vertical manner can be obtained.

If the first portion is not separated from the substrate by the thermal expansion even after the separation by the first laser beam and the boring by the second laser beam as described above, And a first portion removing step of applying physical pressure to the first portion and separating and removing the first portion from the substrate to form the through hole.

Even if the first portion is removed from the substrate by applying physical pressure to the first portion, the first portion is in a state of being separated from the substrate by the separation step and is in a state of being pinched by the substrate by the perforating step , It is possible to remove the edge portion of the first portion with a clean cross section without being damaged by the physical pressure.

Here, the substrate may be at least one of a sapphire substrate, a glass substrate, and a tempered glass substrate used for protecting or displaying a display device. The substrate is made of a transparent material through which light is transmitted, and can be processed by a laser beam.

The first laser beam is formed as a beam having a higher energy output distribution at a spot edge as compared with a center portion of the spot. As a result, the length of light held by the spot is extended to 1 mm, so that the spot can penetrate even a thick substrate, and a penetration line of an accurate cross section can be formed.

The first laser beam has a shorter pulse period than the second laser beam. This is because the pulse period must be a short period corresponding to the microwave in order to form the penetration line formed by the first laser beam vertically penetrating through the substrate thickness thinly.

However, if the second laser beam is formed of the same laser beam as the first laser beam but the second laser beam is formed by the laser beam of the microwave, it takes a long time to perform the boring step, This is expensive and therefore not efficient.

Specifically, the first laser beam is irradiated with a laser beam of a pulse waveform, and the pulse period is formed by a pulsed laser beam of 1 femtosecond to 300 picosecond, so that the outline of the closed curve shape to be cut It is possible to form the through-line through the fine gap.

At this time, the first laser beam can form a through beam along an outline of a closed curve in a precise shape by forming a vessel beam with a laser beam having a wavelength of 300 nm to 1500 nm. The first laser beam is maintained at an output of 5 W to 100 W, so that the penetration line can be formed through an accurate cross section while minimizing heat damage to the substrate.

The second laser beam may be a laser beam having the same wavelength band as the first laser beam and having the same pulse period. However, in this case, since the hole penetrated by the laser beam is very small, it takes a long time to process. Therefore, the second laser beam is a pulsed laser beam having a pulse period of 1 nanosecond to 900 nanosecond, and processing the laser beam in the visible light region having a wavelength of 380 nm to 770 nm shortens the processing time, A configuration effect can be obtained.

The irradiation path of the second laser beam is set to a position spaced apart by an interval of 20 mu m or more to the inside of the first part as compared with the irradiation path of the first laser beam. This is because the first laser beam does not cause brittleness in the brittle material but the second laser beam whose pulse period is much larger than the first laser beam has a fine cracking phenomenon at a position spaced apart from the irradiation position by about 20 to 200 占 퐉 .

Therefore, by irradiating the second laser beam at a position spaced 20 占 퐉 to 200 占 퐉 apart or more from the irradiation position of the first laser beam forming the penetrating line along the closed curve, It is possible to pass through a part of the first part in the closed curve without adversely affecting damage or the like and to mitigate the interference between the first part and the substrate.

Meanwhile, the terms "separation" and " separation " in this specification and claims define the state in which the substrate and the first portion are joined or not integrated. Therefore, even if the first portion and the substrate are in contact with each other, the state in which the first portion and the substrate are separated from each other is a state in which the first portion and the substrate are integrally joined or not connected by a single body .

According to the present invention configured as described above, when a through hole is formed in the shape of a closed curve on a substrate made of a brittle material such as glass or sapphire, a through line passing through a predetermined closed curve is formed by irradiating a first laser beam along the closed curve And a step of separating the first portion surrounded by the closed curve from the substrate and then irradiating the inside of the first portion with the second laser beam to break the inside of the first portion, It is possible to obtain a favorable effect of not only cutting the cut surface for cutting the first portion into a smooth vertical cross-section but also preventing the occurrence of cracks, thereby increasing the yield.

In addition, in the present invention, the chipping size generated in the first portion cut by machining as described above is reduced to 10 탆 or less, which is remarkably improved compared to 300 탆 which is the conventional average chipping size.

This makes it possible to prevent the occurrence of cracks in the processing region during the process of forming the through holes such as the speaker, the home button, and the microphone on the protective substrate or the display substrate of the display device or the mobile device, ) Phenomenon can be suppressed, and the cross section of the through hole can be accurately formed in a short time with a clean and almost vertical orientation, thereby omitting a subsequent machining process and advantageously reducing the cost of machining.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a diagram showing a laser machining to obtain the shape of a closed curve of a brittle material using a conventional laser,
2 is an enlarged view of a machining portion of a brittle material using a conventional laser,
FIG. 3 is a view of a portion of a conventional laser machining operation,
4 is an enlarged photographic view taken along the line AA in Fig. 3,
5 is a flowchart sequentially showing a laser processing method for cutting a brittle material in the form of a closed curve according to the present invention,
FIG. 6A is a schematic view showing a state in which the separation step of FIG. 5 is performed,
FIG. 6B is a plan view of the substrate subjected to the separation step according to FIG. 6A,
FIG. 7A is a schematic view showing a state in which the drilling step of FIG. 5 is performed,
FIG. 7B is a plan view of the substrate subjected to the boring step according to FIG. 7A,
FIG. 8A is a schematic view showing a state in which the removing step of FIG. 5 is performed,
FIG. 8B is a plan view of the substrate subjected to the removal step according to FIG. 8A,
9 is a photograph of a portion processed by the laser machining method of the present invention,
10 is an enlarged view of the cross-sectional view taken along line BB of Fig.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to preferred embodiments and accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the subject matter of the present invention.

FIG. 6 is a schematic view showing a state in which the separation step of FIG. 5 is performed. FIG. 6B is a sectional view of FIG. Fig. 7A is a schematic view showing a state in which the drilling step in Fig. 5 is performed, Fig. 7B is a plan view of the substrate in which the drilling step is performed in Fig. 7A, Fig. Fig. 8 is a plan view of the substrate subjected to the removal step according to Fig. 8A, Fig. 9 is a view showing a portion processed by the laser machining method of the present invention, and Fig. 10 is a cross- FIG.

A laser processing method according to the present invention relates to a processing method for forming a through hole 110 in the form of a closed curve on a substrate 101 made of a brittle material such as glass or sapphire as shown in Fig. A separation step S100 of forming a through line 105a in the form of a closed curve to be cut by irradiating the first laser beam 102 around the closed curve of the first part 110a picked up by the first laser beam 110, A step S200 of forming a plurality of perforation holes in the first portion 110a by irradiating a second laser beam 103 to the inside of the portion 110a and applying a physical pressure to the first portion 110a, Removing the first portion 110a from the first portion 110 to form the through hole 110, and then performing a first portion removing step S300.

Step 1: Separation step ( S100 )

First, as shown in FIG. 6A, a substrate 101 made of a transparent brittle material such as sapphire, glass, tempered glass or the like capable of transmitting light is mounted on a work table as an object to be processed. At this time, a negative pressure is applied to the plurality of suction holes formed in the work table so that the substrate 101 to be fixed on the work table is fixed in place during the machining process.

The first laser beam 102 is then irradiated from the laser beam irradiator 12 along the outline of the first portion 110a to be cut from the substrate 101 to form a thin penetrating penetration through the substrate 101 Causing line 105a to form along the closed curve. The laser oscillator for supplying the laser beam to the laser beam irradiator 12 is a laser oscillator in which the laser beam in the single mode state of the TEM ₀₀ of the transverse mode laser showing the energy distribution in the plane perpendicular to the output optical axis Supply.

First of all, the first laser beam 102 is irradiated with a laser beam of a pulse waveform, and in particular, a pulsed laser beam having a pulse period of from 1 femtosecond to 300 picosecond is formed, The output of the laser beam 102 is adjusted to 5W to 100W to move the spot of the first laser beam 102 along the outline of the closed curve to be cut.

It is preferable that the optical system forming the first laser beam 102 is irradiated in the form of a vessel beam distributed at a high energy density even in the edge region spaced apart from the center of the optical path. Furthermore, by using an ultrashort-pulse laser having a pulse period of 300 picoseconds or less, a laser beam passing through an axicon lens of an optical system not shown in the drawing is converted into a Bessel beam, As shown in Fig.

When the first laser beam 102 passes through the substrate 101 once, it is possible to form only the penetrating line 105a through the fine gap without causing heat damage or cracking in the periphery.

If the pulse period exceeds 300 picoseconds, only the penetration line 105a can not be formed with a minute gap, and thermal damage or cracking is caused in the periphery, so that a clean vertical cross section can not be formed.

The first laser beam 102 can be selected as a laser beam having various wavelength bands, and a laser beam in the infrared, visible, and ultraviolet wavelength bands of 300 nm to 1500 nm can be selected. If the wavelength of the first laser beam 102 is larger than 1500 nm, the output must be increased to 100 W or more to penetrate the substrate 101. In this process, thermal damage or cracking may occur in the periphery of the through line 105a . Therefore, it is preferable that the wavelength of the first laser beam 102 is 1500 nm or less.

As described above, when the first laser beam 102 is moved along the closed curve forming the circumferential boundary of the first portion 110a to be cut by adjusting the first laser beam 102, as shown in FIG. 6B, A through hole 105a is formed in which the first portion 110a is separated from the substrate 110 while a thin width gap is formed. The width of the through line 105a is cut very narrowly and the first portion 110a is not caught in the substrate 101 despite the through line 105a due to the thermal expansion XF of the substrate material, .

Step 2: Perforation step ( S200 )

If the penetration line 105a is formed with a small width around the first portion 110a to be cut out by the separation step S100, as shown in FIG. 7A, the first portion 110a is irradiated with the second laser beam The first part 110a is irradiated with the first part 110a and the first part 110a is pierced by a plurality of holes so as to relax the state of being caught by the substrate 101 at the edge of the first part 110a, So as to be separated from the substrate 101.

More specifically, as shown in Fig. 7A, the second laser beam 103 irradiated from the laser irradiator 13 is irradiated from the cutting line 105a formed between the first portion 110a and the substrate 101 The first portion 110a is irradiated to the first portion 110a on the inner side (away from the substrate), and the first portion 110a is crushed while forming a plurality of the perforation holes 106. [

For this purpose, the laser beam having the intensity that allows the second laser beam 103 to pass through the substrate 101 can be variously applied. For example, it is possible to use a laser beam of a wavelength band having an infrared wavelength from the ultraviolet ray region, or a carbon dioxide laser beam of 9000 nm or more. A laser beam of a continuous waveform can be used, and a laser beam of a pulse waveform can also be used.

At the same time, the second laser beam 103 may use a laser beam having the same pulse period in the same wavelength band as that of the first laser beam 102. In this case, there is an advantage that the separation step (S100) and the boring step (S200) can be performed using one equipment. However, when the second laser beam 103 is used with the same laser beam as that of the first laser beam 102, since holes for penetrating and puncturing by the laser beam are very small, it takes a long time for processing, There is a problem that the use time of the laser beam irradiator becomes long.

Therefore, the second laser beam 103 is a pulsed laser beam having a pulse period of 1 nanosecond to 900 nanosecond, and it is preferable to process the laser beam in the visible light region having a wavelength of 380 nm to 770 nm, The processing time can be shortened and the perforation hole 106 can be formed at a low cost and can be crushed.

At this time, the laser oscillator which supplies the laser beam to the laser beam irradiator 13 can be supplied, for example, to the laser beam in the single mode state of the TEM ₀₀ of the transverse mode laser showing the energy distribution in the plane perpendicular to the output optical axis .

The movement path of the second laser beam 103 is shifted from the through line 105a formed by irradiation with the first laser beam 102 to the inside toward the center of the first portion 110a by 20 占 퐉 to 200 占 퐉 . The second laser beam 103, which has a pulse period longer than the first laser beam 102, does not cause a breakage phenomenon in the substrate 101, which is a brittle material, Minute cracking occurs to a position spaced by 200 占 퐉.

Therefore, there is a difference between the specifications of the second laser beam 103 and the thickness and material of the substrate 101, but the movement path of the second laser beam 103 is shifted from the through line 105a It is preferable that the distance d is set at least 20 mu m or more. According to a preferred embodiment, the movement path of the second laser beam 103 is determined from the through line 105a at an interval d of 80 占 퐉 to 150 占 퐉.

At this time, the perforation holes 106 passing through the first portion 110a by the second laser beam 103 may be spaced apart from each other, and as shown in FIG. 7B, a perforation hole 106 is formed Or may be formed in a continuous shape, and another through line may be formed in a single continuous line shape.

By forming a plurality of perforation holes 106 in the first portion 110a by the second laser beam 103 as described above, the vicinity of the edge of the first portion 110a is broken to form the first portion 110a ) Is sandwiched between the through-holes 105a and the substrate 101, thereby lowering the strength of the interposition. Accordingly, the first portion 110a can be separated from the substrate 101 by itself or can be separated from the substrate 101 by applying a weak force.

The removal of the first part ( S300 )

The perforation hole 106 may be formed in the perforation line 105a formed around the first portion 110a by the perforation step S200 so that the first portion 110a In the case of separating from the substrate 101 by itself, the removal step (S300) of the first part is not performed.

However, it may take a long time to form the perforation hole 106 inside the penetrating line 105a and to crush the first portion 110a by the second laser beam 103 so that the first portion 110a itself falls off. Therefore, when the strength of the first portion 110a interfering with the substrate 101 is sufficiently lowered in the perforating step S200, as shown in FIG. 8A, an empty space is formed below the first portion 110a And the presser tool 104 is moved downward so that the first portion 110a is pressed downward so that the first portion 110a is separated from the substrate 101. [

Through this, a predetermined through hole 110 is formed in the substrate 101.

In the laser processing method of the present invention having the above-described structure, the through-line 105a is formed in a fine through-hole shape along the outline of the closed curve through the separation step S100, The state where the first portion 110a is sandwiched by the substrate 101 is weakly weakened by forming the perforation hole 106 in the inner portion of the fine width through line 105a, , The first part 110a is removed by applying a force to push down the first part 110a through the first side part 110a of the processing side wall 105 The taper is not formed, and the processed side wall 105 is formed almost vertically.

In addition, the laser machining method according to the present invention can achieve an excellent effect of the machining quality because the chipping rarely occurs on the average of about 10 mu m during the machining process. In addition, since the machining side wall 101 is directly formed vertically and no taper is formed, it is possible to omit the subsequent machining step for removing the taper having a low impact resistance, thereby advantageously reducing the machining time while reducing the machining cost Can be obtained.

Example - tempered glass

In the embodiment of the present invention, laser processing is performed in which the shape of a closed curve is obtained in a tempered glass under the following conditions.

Step 1 : First, an infrared laser beam having a wavelength of 1064 nm, a pulse period of 100 picoseconds, a frequency of 200 kHz, and an output of 30 W is incident on the closed curve of the tempered glass as the first laser beam 102 A through line 105a is formed along the outline, and a separation step S100 is performed.

Step 2 : Then, a visible light laser beam having a wavelength of 532 nm, a pulse period of 30 nanoseconds, a frequency of 50 kHz, and an output of 30 w is placed at a position spaced by 100 占 from the through line 105a Followed by drilling step S200 by crushing the perforation hole 106 while continuing and discontinuously repeating the irradiation.

Step 3 : Finally, the first part 110a is pushed downward by the pressing tool 104 having the rubber contact material on the lower side to separate the first part 110a away from the substrate 101 to form the through hole 110, .

The processing quality through the above-described embodiment is as shown in photographs of FIG. 9 and FIG. Fig. 7 is a photograph of a portion processed by the laser machining method of the present invention, and Fig. 8 is an enlarged photograph of a cross section taken along the line B-B of Fig.

7, which shows the first part 110a in the form of a closed curve from the substrate 101 of brittle material according to the embodiment of the present invention, when compared with FIG. 3 in which the closed curve type is obtained by the conventional laser processing method, it can be confirmed that chipping is hardly occurred and molding is clean.

8, the machined end face 105 of the through hole 110 is not formed with a taper in the machined end face 105 in comparison with Fig. 4 in which a through-hole in the form of a closed curve is drawn by the conventional laser machining method And it was confirmed that there was no thermal damage at all.

As described above, in the laser machining method according to the present invention, since chipping rarely occurs and a taper is not formed on the machined end face as described above, a subsequent process is not required, so that high-quality machining is possible and machining cost can be reduced .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. That is, it will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims, And is within the scope of the present invention. The above-described embodiments described with reference to the accompanying drawings are for the purpose of illustrating the present invention, and the scope of the present invention is not limited to these embodiments.

S100: Separation step, S200: Perforation step
S300: removal step, 101: substrate
102: first laser beam, 103: second laser beam
104: pressing machine, 105: machining side wall
105a: through line, 110: through hole
110a: first part

Claims

As a method for picking up a through-hole in the shape of a closed curve of an area of several tens of times or more of a laser beam spot on a substrate made of a brittle material,
Wherein the first laser beam has a higher energy output distribution at the edge of the spot than the center of the spot and has a femtosecond to the center of the spot, Wherein the first portion is a pulse laser beam having a pulse period of from 300 to 300 picoseconds and is separated from the substrate by a penetrating line formed by irradiation of the first laser beam, ;
Wherein the first laser beam is irradiated with a second laser beam while being separated from the substrate by the penetrating line, the second laser beam having a pulse period of from 1 nanosecond to 900 nanoseconds nanosecond in a longer pulse cycle than the first laser beam and a plurality of holes are formed in the first portion by irradiation of the second laser beam, A perforation step for lowering the strength of the inserted pinch;
A first portion removing step of applying pressure to the first portion and separating the substrate from the substrate after the perforating step to form the through hole;
And a laser beam.

The method according to claim 1,
Wherein the substrate is any one of a sapphire substrate, a glass substrate, and a tempered glass substrate.

The method according to claim 1,
Wherein the substrate is made of a material through which light is transmitted.

The method according to claim 1,
Wherein the first laser beam is a laser beam having a wavelength of 300 nm to 1500 nm.

The method according to claim 1,
Wherein the second laser beam is a laser beam having a wavelength of 380 nm to 770 nm.

6. The method according to any one of claims 1 to 5,
Wherein the irradiation path of the second laser beam is a position spaced apart by an interval of 20 占 퐉 or more from the inside of the first part to the irradiation path of the first laser beam.

6. The method according to any one of claims 1 to 5,
Wherein the first laser beam has an output of 5W to 100W.

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