JP2018065743A - Method for fusing glass substrate by laser beam and laser processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fuse two glass substrates using a simple process and an optical system.SOLUTION: A method comprises a first step of placing a first glass substrate on a work table, a second step of irradiating the first glass substrate with a laser beam having a wavelength of 2.7 μm or more and 6.0 μm or less to form a projection having a predetermined height on a surface of the first glass substrate, a third step of superimposing a second glass substrate on the first glass substrate using the projection of the first glass substrate as a spacer and a fourth step of irradiating a region having a space between the first and second glass substrates except the projection with the laser beam and fusing the first and second glass substrates.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a glass substrate fusing method, and more particularly to a glass substrate fusing method for irradiating a laminated glass substrate with laser light to fuse the glass substrates together, and a laser processing apparatus using the glass substrate fusing method.

  For example, in an apparatus for IT equipment, a device in which two glass substrates are superimposed is used. Patent Document 1 discloses a method and an apparatus for joining two laminated glass substrates.

  In the glass substrate bonding method disclosed in Patent Document 1, first, a frit wall is formed by pre-sintering a frit on the surface of a glass substrate as a back plate. Then, a glass substrate as a cover plate is overlaid on the back plate on which the frit wall is formed. Thereafter, the frit wall is irradiated with laser light. As a result, the frit wall is heated and hardened by the laser beam, the frit wall is joined to both the back plate and the cover plate, and the two plates are joined.

  Patent Document 2 discloses a method of bonding two glass substrates using a short pulse laser beam. Here, high-energy short-pulse laser light is condensed in the vicinity of the gap between the two glass substrates, and the two glass substrates are joined by causing multiphoton absorption.

Special table 2012-533853 gazette International Publication 2011/115242

  For example, in a liquid crystal display device, a predetermined gap is secured between two glass substrates, and the space between the two glass substrates is sealed in that state. In order to realize such a configuration, first, a spacer is disposed between two glass substrates, and then the two glass substrates are fused by the method shown in Patent Document 1 or 2. It is conceivable to seal.

  However, the above method requires a spacer material between the two glass substrates. In the method of Patent Document 1, it is necessary to pre-sinter the frit to the surface of the back plate once. In order to pre-sinter the frit, it is necessary to put the cover plate or the frit in an oven or a furnace and heat it, and the process becomes complicated.

  Furthermore, in the method of Patent Document 2, short pulse laser light is used, but short pulse laser light is expensive. Further, in the method of Patent Document 2, it is necessary to reduce the spot diameter of the laser beam in order to generate the multiphoton absorption phenomenon, and thus a complicated apparatus is required for the condensing optical system and the focus position control. It becomes.

  An object of the present invention is to enable both glass substrates to be bonded using a simple process and an optical system, and without a spacer material, with a predetermined gap between the two glass substrates. It is in.

  The glass substrate fusion method using a laser beam according to the first aspect of the present invention is a method of irradiating laser beams onto an overlapped glass substrate to fuse the glass substrates together, and includes the following steps.

  1st process: A 1st glass substrate is mounted on a work table.

  Second step: The first glass substrate is irradiated with laser light having a wavelength of 2.7 μm or more and 6.0 μm or less to form a convex portion having a predetermined height on the surface of the first glass substrate.

  Third step: The second glass substrate is overlaid on the first glass substrate using the convex portion of the first glass substrate as a spacer.

  Fourth step: The first glass substrate and the second glass substrate are fused by irradiating a region other than the convex portion with laser light.

  In this method, first, a first glass substrate placed on a work table is irradiated with a laser beam having a wavelength of 2.7 μm or more and 6.0 μm or less, whereby the inside of the first glass substrate is heated, and the laser beam is emitted. The irradiated portion melts and expands, and a convex portion is formed on the surface of the first glass substrate. Next, a second glass substrate is overlaid on the first glass substrate on which the convex portions are formed using the convex portions as spacers. Then, the same laser beam as that of the previous laser beam is irradiated to the region other than the convex portion. As a result, the portions of the first glass substrate and the second glass substrate irradiated with the laser light are melted, and the two glass substrates are bonded together with a gap substantially corresponding to the height of the convex portion.

  Here, without using a spacer material or frit, and using the same laser light in the step of forming the convex portion and the step of fusing the two glass substrates, a gap is formed between the two glass substrates and the two glasses are formed. The substrates can be joined. This simplifies the process. Further, since the two glass substrates are fused without using the multiphoton absorption phenomenon, it is not necessary to control the condensing position with high accuracy, and the apparatus configuration is simplified.

  The method for fusing a glass substrate with a laser beam according to the second aspect of the present invention is the method of the first aspect, wherein a laser beam having a wavelength of 2.7 μm to 5.0 μm is applied to the glass substrate in the second and fourth steps. Irradiate against.

  Here, since a mid-infrared laser beam having a relatively high transmittance to glass is used, even when the thickness of one glass substrate irradiated with the laser beam is relatively thick, the laser beam is transmitted to the other glass substrate. Reach and stably fuse the glass substrate.

  The method for fusing a glass substrate with a laser beam according to the third aspect of the present invention is the method of the first or second aspect. In the second and fourth steps, the laser beam is irradiated along the planned fusion line. Scan.

  Here, two glass substrates can be fused along a continuous fusion schedule line. Therefore, the space formed between the two glass substrates can be sealed.

  The glass substrate fusion method using laser light according to the fourth aspect of the present invention is the method of any one of the first to third aspects. In the second step and the fourth step, continuous wave laser light is applied to the glass substrate. Irradiate.

  Here, since continuous oscillation laser light is used, a uniform continuous melted portion can be formed along the planned fusion line, and the two glass substrates can be easily and firmly fused.

  The glass substrate fusion method using laser light according to the fifth aspect of the present invention is the method of any one of the first to third aspects, in the second step and fourth, a quasi-continuous laser having a repetition frequency of 1 MHz or more. Light is applied to the glass substrate.

  Here, since pseudo continuous oscillation laser light is used, a substantially uniform continuous melted portion can be easily formed in the same manner as continuous oscillation laser light.

  The glass substrate fusion method using laser light according to the sixth aspect of the present invention is the method of any one of the first to third aspects. In the second step and the fourth step, pulse laser light having a repetition frequency of 10 kHz or more is used. Irradiate the glass substrate.

  Here, since pulsed laser light having a repetition frequency of 10 kHz or more is used, it is possible to form a melted portion in which the melted portions formed for each pulse of the pulsed laser are overlapped and continuous.

  The glass substrate fusion method using laser light according to the seventh aspect of the present invention is the method of any one of the first to sixth aspects, wherein in the third step, the second glass substrate is pressed against the first glass substrate. Overlapping without any.

  Here, it is not necessary to press the two glass substrates together, and the apparatus configuration is simplified.

The glass substrate fusion method using a laser beam according to the eighth aspect of the present invention is the method of any one of the first to seventh aspects, wherein Er: Y ₂ O ₃ , Er: ZBLAN is used in the second and fourth steps. Er: YSGG, Er: GGG, Er: YLF, Er: YAG, Dy: ZBLAN, Ho: ZBLAN, CO, Cr: ZnSe, Cr: ZnS, Fe: ZnSe, Fe: ZnS, in the mid-infrared of a semiconductor laser One of the laser beams selected from the laser beam group is irradiated onto the glass substrate.

  In the glass substrate fusion method using laser light according to the ninth aspect of the present invention, the glass substrate has an internal absorption rate of laser light of 5% or more and 95% or less in any of the methods of the first to eighth aspects.

  The glass substrate processing apparatus using a laser beam according to the tenth aspect of the present invention is an apparatus for irradiating laser beams onto an overlapped glass substrate to fuse the glass substrates together. This apparatus includes a work table on which a glass substrate is placed, a laser oscillator, and a laser beam irradiation mechanism. The laser oscillator oscillates a laser beam having a wavelength of 2.7 μm to 6.0 μm. The laser light irradiation mechanism irradiates the surface of the first glass substrate placed on the work table with the laser light from the laser oscillator to form a convex portion having a predetermined height on the surface of the first glass substrate. In addition, the laser light irradiation mechanism irradiates a region other than the convex portion with laser light in a state where the second glass substrate is superimposed on the first glass substrate with the convex portion of the first glass substrate as a spacer. The substrate and the second glass substrate are fused.

  The laser processing apparatus according to the eleventh aspect of the present invention is the apparatus according to the tenth aspect, wherein the laser oscillator oscillates a mid-infrared laser beam having a wavelength of 2.7 or more and 5.0 μm or less.

  The laser processing apparatus according to the twelfth aspect of the present invention is the apparatus according to the tenth or eleventh aspect, wherein the laser light from the laser light irradiation mechanism is moved relative to the glass substrate to fuse the laser light. A scanning mechanism for scanning along the line is further provided.

  The laser processing apparatus according to the thirteenth aspect of the present invention is the apparatus according to any one of the tenth to twelfth aspects, wherein the laser oscillator continuously oscillates the laser beam.

  A laser processing apparatus according to a fourteenth aspect of the present invention is the apparatus according to any one of the tenth to twelfth aspects, wherein the laser oscillator quasi-continuously oscillates laser light having a repetition frequency of 1 MHz or more.

  The laser processing apparatus according to the fifteenth aspect of the present invention is the apparatus according to any one of the tenth to twelfth aspects, wherein the laser oscillator oscillates pulsed laser light having a repetition frequency of 10 kHz or more.

The laser processing apparatus according to the sixteenth aspect of the present invention is the apparatus according to any one of the tenth to fifteenth aspects, wherein the laser oscillator is Er: Y ₂ O ₃ , Er: ZBLAN, Er: YSGG, Er: GGG, Er. : YLF, Er: YAG, Dy: ZBLAN, Ho: ZBLAN, CO, Cr: ZnSe, Cr: ZnS, Fe: ZnSe, Fe: ZnS, any one selected from the mid-infrared laser light group of semiconductor lasers The laser beam is irradiated to the glass substrate.

  In the present invention as described above, both glass substrates can be bonded with a predetermined gap between the two glass substrates by using a simple process and an optical system.

1 is a schematic configuration diagram of a laser processing apparatus according to an embodiment of the present invention. The figure which shows the relationship between the wavelength of the laser beam with respect to an alkali free glass, and the transmittance | permeability. The figure which shows the relationship between the wavelength of the laser beam with respect to soda glass, and the transmittance | permeability. The microscope picture of the convex part formed in the glass substrate, and its conceptual diagram. The table | surface which shows the relationship between the focus position and scanning speed of a laser beam, and a convex part dimension. The schematic diagram at the time of laminating | stacking two glass substrates.

[Laser processing equipment]
A laser processing apparatus according to an embodiment of the present invention is shown in FIG. This laser processing apparatus includes a work table 1 on which a glass substrate G is placed, a laser oscillator 2, an optical system 3, and a table moving mechanism 4 as a scanning mechanism.

The laser oscillator 2 oscillates a mid-infrared laser beam having a wavelength of 2.7 μm to 6.0 μm. Here, as the laser oscillator 2, Er: Y ₂ O ₃ , Er: ZBLAN, Er: YSGG, Er: GGG, Er: YLF, Er: YAG, Dy: ZBLAN, Ho: ZBLAN, CO, Cr: ZnSe, Laser light selected from Cr: ZnS, Fe: ZnSe, Fe: ZnS, and mid-infrared laser light group of semiconductor lasers, having a wavelength of 2.7 to 6.0 μm as described above. Anything to do. Here, continuous-wave laser light is emitted.

  The optical system 3 includes a plurality of reflecting mirrors 6 a, 6 b, 6 c and a condenser lens 7. As an example, the condensing lens 7 is set to condense the laser light near the surface of the glass substrate G.

  The table moving mechanism 4 is a mechanism for moving the work table 1 in the X and Y directions orthogonal to each other. The table moving mechanism 4 can scan the laser light along the fusion line.

[Glass substrate processing method]
When the second glass substrate G2 is bonded to the surface of the first glass substrate G1 with a predetermined interval using the above laser processing apparatus, the following steps are performed.

[First and second steps]
First, the first glass substrate G1 is set at a predetermined position on the work table 1. Next, the mid-infrared laser beam as described above is focused on the first glass substrate G1 near the surface and irradiated to the first glass substrate G1 on the work table 1. Scan along the line. The focal position point of the laser beam is not limited to the surface of the first glass substrate G1.

  By the continuous irradiation and scanning of the laser light as described above, a convex portion is formed so that the surface of the first glass substrate G1 is irradiated with the laser light. The height and width of the convex portion can be adjusted by the focal position of the laser beam and the scanning speed.

  In particular, by using a mid-infrared laser beam having a wavelength of about 3 μm, the laser beam is absorbed while being transmitted to the inside of the glass substrate. For this reason, the unevenness of the heat distribution is reduced from the surface to the inside of the glass substrate, the thermal damage of the glass substrate can be suppressed, and a convex portion having a predetermined height can be easily formed in the laser light irradiation portion.

<Transmittance and wavelength>
FIG. 2 shows the relationship between the wavelength and transmittance of laser light with respect to a glass substrate of non-alkali glass (for example, OA10 (product name: manufactured by Nippon Electric Glass Co., Ltd.)) having a thickness of 0.2 mm. FIG. 3 shows the relationship between the wavelength and transmittance of laser light for a soda glass glass substrate having a thickness of 0.5 mm.

  As is clear from FIG. 2, for non-alkali glass having a thickness of 0.2 mm, for example, the transmittance is “0” in a CO2 laser having a wavelength of 10.6 μm, so that the laser light is absorbed by the surface of the substrate. Will be. Further, in the case of a YAG laser having a wavelength of 1 μm or a green laser having a wavelength of 532 nm, the transmittance is 90% or more, and almost 10% of laser light that does not pass through is reflected on the surface and is not absorbed into the substrate. If the laser beam has a wavelength of 2.8 μm, it can be absorbed almost uniformly inside the substrate, and the inside of the substrate can be melted to form a convex portion on the surface of the glass substrate.

  Further, in the soda glass having a plate thickness of 0.5 mm in FIG. 3, the laser beam having a wavelength of 2.8 μm is absorbed while transmitting the laser beam to the inside of the substrate. Therefore, like the alkali-free glass in FIG. The inside can be melted to form a convex portion having a predetermined height on the surface.

  The difference in transmittance between the graphs shown in FIG. 2 and FIG. 3 is due to the difference in the thickness of the sample. If the thickness is the same, the transmission between the alkali-free glass and the soda glass is possible. There seems to be no difference in rate.

  From the above, by using laser light having a wavelength of 2.7 μm or more and 6.0 μm or less, for many glass substrates (particularly glass substrates having an internal absorption rate of laser light of 5% or more and 95% or less), It is presumed that a convex portion having a predetermined height can be easily formed in the irradiated portion of the laser beam. Further, even when the thickness of the substrate to which the laser beam is irradiated is relatively thick, a convex portion can be formed on the glass substrate by using a laser beam having a wavelength of 2.7 μm or more and 5.0 μm or less.

<Experimental example: formation of convex part>
FIGS. 4A and 4B show how convex portions are formed on the surface of the glass substrate when the glass substrate is irradiated with the above-described mid-infrared laser beam. FIG. 4A is a micrograph of a cross section of a laser beam irradiated portion, and FIG. 4B is a conceptual diagram thereof. The glass substrate and laser irradiation conditions in this experiment are as follows.

Substrate: non-alkali glass (OA10 = product name: manufactured by Nippon Electric Glass Co., Ltd.), size = 100 mm × 125 mm × t 0.2 mm
Laser light: Er: ZBLAN fiber laser, wavelength 2.7 μm, output 7 W, continuous oscillation In this experiment, the laser light was scanned in the direction perpendicular to the paper surface of FIG. As a result, convex portions were continuously formed along the scanning line, and the dimensions were 10 μm width × 1 μm height to 40 μm width × 8 μm height. Here, as shown in the conceptual diagram of FIG. 4B, it is considered that the glass substrate is formed with three layers, that is, the expansion portion, the altered portion, and the heat affected zone.

  FIG. 5 collectively shows how the convex portions are formed when the focal position is changed from +0.4 mm to −0.4 mm and the scanning speed is changed from 15 mm / s to 35 mm / s. ing. In the figure, “+0.4 mm” to “−0.4 mm” are the focal positions of the laser light, “0 mm” is the surface of the glass substrate, and “−” is the position inside the substrate. The numerical unit in the table is “μm”. In the figure, “F” represents the fluctuation width of the height, that is, the difference between the maximum value and the minimum value of the height in the measurement line (substantially the same as the center line of the processing line) set at the center of the expansion width. .

  FIG. 5 shows the following.

  (A) When the focal position of the laser beam is set to the substrate surface (0 mm), the laser beam is most easily expanded. However, if the focal position is in the range of +0.4 mm to −0.4 mm, a convex portion having a desired height can be formed on the surface of the glass substrate by appropriately controlling the scanning speed of the laser beam. .

  (B) When the scanning speed is increased, the processed trace can be observed, but the convex portion due to expansion is not formed. That is, in order to form a convex part, it is necessary to give a certain amount of heat to a board | substrate.

  (C) The expansion size is larger when the focal position of the laser beam is set to “−” (inside the substrate). Note that FIG. 5 does not show the actual focal position because the refractive index of the glass is not taken into consideration.

  (D) When the focal position of the laser beam is separated from the surface of the glass substrate, the fluctuation width of the height increases.

  From the above, if the focal position is set in the vicinity of the glass substrate surface using the laser beam having the wavelength as described above, the convex portion of the desired height can be stably stabilized by controlling the scanning speed. It can be seen that it can be formed.

[3rd to 4th steps]
Next, as shown in the schematic diagram of FIG. 6, the second glass substrate G <b> 2 is overlaid on the first glass substrate G <b> 1 on which the convex portion B is formed, with the convex portion B functioning as a spacer. Then, the region R other than the convex portion B is irradiated with the laser light under the same laser light irradiation condition as that for forming the convex portion B. As a result, the laser light irradiation region R of the first glass substrate G1 expands in the same manner as when the convex portion B is formed, and the tip of the expanded portion and the back surface of the second glass substrate G2 (first glass substrate G1). And the surface facing each other).

[Usage]
The method as described above is effective when two laminated glass substrates are fused and sealed with a predetermined gap therebetween. That is, the space inside the region R in FIG. 6 is sealed by making the fusion line continuous and closing.

[Feature]
(1) It is possible to join the two glass substrates with a gap without using a separate spacer material.

  (2) Two glass substrates can be fused without using a frit.

  (3) In the step of forming the convex portion and the step of fusing the two glass substrates, the same laser beam can be used, and the step for fusing becomes simple.

  (4) It is not necessary to control the condensing position with high accuracy, and the apparatus configuration is simplified.

  (5) By irradiating the glass substrate with the mid-infrared laser beam, the convex portion having a desired height can be accurately obtained without controlling the output of the laser beam or heating or pressing in a subsequent process. Can be formed.

  (6) The height of the convex portion can be controlled by adjusting the focal position and scanning speed of the laser beam.

  (7) The laser light is absorbed while penetrating into the glass substrate, and is thus heated uniformly from the surface to the inside of the glass substrate. Therefore, a convex part can be formed in the surface of a glass substrate, suppressing the heat damage of a glass substrate.

[Other Embodiments]
The present invention is not limited to the above-described embodiments, and various changes or modifications can be made without departing from the scope of the present invention.

  In the above-described embodiment, continuous wave laser light is used. However, pseudo continuous wave laser light with a repetition frequency of 1 MHz or higher, or pulsed laser light with a repetition frequency of 10 kHz or higher may be irradiated.

DESCRIPTION OF SYMBOLS 1 Work table 2 Laser oscillator 3 Optical system 4 Table moving mechanism B Convex part G1, G2 Glass substrate

Claims (7)

A method for fusing glass substrates in which a glass substrate is irradiated with laser light to fuse the glass substrates together,
A first step of placing the first glass substrate on the work table;
A second step of forming a convex portion having a predetermined height on the surface of the first glass substrate by irradiating the first glass substrate with laser light having a wavelength of 2.7 μm or more and 6.0 μm or less;
A third step of superposing a second glass substrate on the first glass substrate using the convex portion of the first glass substrate as a spacer;
The first glass substrate and the second glass substrate are fused by irradiating a region having a gap between the first glass substrate and the second glass substrate other than the convex portion with a laser beam having the wavelength. And a fourth step to
A method for fusing a glass substrate with laser light.   The glass substrate fusion method using laser light according to claim 1, wherein in the second step and the fourth step, a laser beam having a wavelength of 2.7 μm or more and 5.0 μm or less is irradiated to the glass substrate.   The glass substrate fusion method using laser light according to claim 1, wherein, in the second step and the fourth step, scanning is performed along a planned fusion line while irradiating the laser light.   4. The glass substrate processing method using laser light according to claim 1, wherein the first and second glass substrates have an internal absorption rate of laser light of 5% to 95%. A laser processing apparatus for irradiating laser beams onto a laminated glass substrate and fusing the glass substrates together,
A work table on which a glass substrate is placed;
A laser oscillator that oscillates a laser beam having a wavelength of 2.7 μm to 6.0 μm;
The surface of the first glass substrate placed on the work table is irradiated with laser light from the laser oscillator to form a convex portion having a predetermined height on the surface of the first glass substrate, and the first glass Between the first glass substrate and the second glass substrate other than the portion where the convex portion is formed in the state where the convex portion of the substrate is used as a spacer and the second glass substrate is superimposed on the first glass substrate. A laser beam irradiation mechanism that fuses the first glass substrate and the second glass substrate by irradiating a region having a gap with the laser beam having the wavelength;
A laser processing apparatus comprising:   The laser processing apparatus according to claim 5, wherein the laser oscillator oscillates a mid-infrared laser beam having a wavelength of 2.7 to 5.0 μm.   The laser according to claim 5, further comprising a scanning mechanism that moves the laser light from the laser light irradiation mechanism relative to the glass substrate and scans the laser light along a planned fusion line. Processing equipment.