CN114227015A

CN114227015A - Method and system for cutting sapphire by deep ultraviolet ultrafast laser

Info

Publication number: CN114227015A
Application number: CN202210026222.5A
Authority: CN
Inventors: 不公告发明人
Original assignee: Beijing Yingke Technology Co ltd
Current assignee: Beijing Yingke Technology Co ltd
Priority date: 2022-01-11
Filing date: 2022-01-11
Publication date: 2022-03-25

Abstract

The invention provides a deep ultraviolet ultrafast laser sapphire cutting method and a system, wherein the method comprises the following steps: 1) fixing the sapphire workpiece on a workbench through a fixing device; 2) laser emitted by a laser device sequentially passes through a shaping light path, a light beam transmission light path and a laser cutting head and is focused on the surface of a sapphire workpiece on a workbench; the laser cutting head is arranged above the sapphire through a driving system; 3) the laser is a deep ultraviolet ultrafast laser; 4) the cutting of the sapphire workpiece is accomplished by controlling the speed of travel of the laser beam on the axis X, Y, Z of the sapphire workpiece surface. The invention cuts sapphire based on the locked ultrafast laser with high repetition frequency, single-pulse working, high single-pulse energy and high single-pulse energy consistency, and has good photon consistency and high cutting precision.

Description

Method and system for cutting sapphire by deep ultraviolet ultrafast laser

Technical Field

The invention relates to the technical field of laser cutting, in particular to a method and a system for cutting deep ultraviolet ultrafast laser sapphire.

Background

Sapphire is a single crystal of alumina, has a unique lattice structure, is wear-resistant and weather-resistant, has a mohs hardness as high as 9, and is inferior to diamond. In the early stage, the alloy is scarce due to high hardness, wear resistance, glossiness and light transmittance and high requirements on processing level, and only appears on the surfaces of jewelry and watches, so that the alloy is expensive in selling price.

With the adoption of sapphire as the protective glass of a camera and the Home key protective glass by apple companies, sapphire materials have been widely applied to smart phones and wearable devices, and a wider increment space is brought in the fields of aviation, national defense, LEDs, medical treatment, consumer electronics and the like. With LED substrates being the most dominant downstream application of sapphire, the market proportion is over 50%.

These applications require the fine processing of sapphire. However, because sapphire is a hard and brittle material, cracks, fragments, delamination, edge breakage and cutter abrasion are easy to generate in the traditional mechanical processing, and because sapphire has good chemical stability, the traditional chemical processing method has the difficult problems of difficult processing and the like until the laser cutting technology appears.

The difficulty in laser cutting of sapphire, especially cutting of sapphire by a traditional fiber ultrafast picosecond and femtosecond laser, is in controlling laser parameters, peak power density, and other operation parameters and related processing technologies. For example, as the burst energy increases from 30uJ to 150uJ, the process length increases from 100um to 250 um. As the burst energy increases from 150uJ to 200uJ, the process length remains almost unchanged. That is, the machining length initially increases with increasing burst energy, but saturates after the burst energy exceeds 150 uJ. The most important reasons are that the processing threshold saturation phenomenon is caused by uneven single pulse energy, asynchronous pulse time and energy scattering caused by time domain drift in a pulse train.

In order to ensure that the processing length of the sapphire exceeds the saturation threshold, the common method is to adopt a 'stealth cutting' mode, form a plurality of focuses reaching the approximate saturation threshold at the focus position in the laser transmission direction by using a special cutting head, and cut the sapphire with the thickness of more than 250um after the accumulated processing length in the effective processing area and the irradiation of the focus position. However, for such low thermal conductivity, hard and brittle materials, the accumulated pulse train energy may cause local ultra-rapid temperature rise, which may result in cracking of the sample, possible micro-cracking in the processing area, and irregular distribution of the joining positions, and may also affect the quality of the cutting piece. Therefore, according to the characteristics of the ultra-fast laser processing of sapphire, a proper ultra-fast laser parameter process is selected and optimized for relevant processing combination parameters, so that a higher cutting effect is achieved.

Disclosure of Invention

In view of the above, to overcome the deficiencies of the prior artThe invention provides a method and a system for cutting sapphire by deep ultraviolet ultrafast laser. The single pulse power density of the method can reach as high as 10¹²W/cm²In the above, the material in the laser-active region is instantaneously evaporated or vaporized, and a saturated processing length is hardly formed in the sapphire material.

The invention provides a method for cutting sapphire by using deep ultraviolet ultrafast laser, which comprises the following steps:

1) fixing the sapphire workpiece on a workbench through a fixing device;

2) laser emitted by a laser device sequentially passes through a shaping light path, a light beam transmission light path and a laser cutting head and is focused on the surface of a sapphire workpiece on a workbench; the laser cutting head is arranged above the sapphire through a driving system;

3) the laser is a deep ultraviolet ultrafast laser capable of emitting single pulse with frequency locking and uniform energy; the emission frequency of the laser is a certain value between 50KHz and 100 KHz; the single pulse energy emitted by the laser is 200uJ-400uJ, and the consistency of the single pulse energy is less than or equal to +/-5%;

4) and the cutting of the sapphire workpiece is completed by controlling the traveling speed of the laser beam of the laser cutting head on the surface X, Y, Z axis of the sapphire workpiece.

Further, the laser is an all-solid-state picosecond laser.

Furthermore, the laser has a window light spot of 1-3mm and a divergence angle of 0.5-1.5 mrad.

Further, the transmission distance of the light beam transmission light path is 200-1000 mm.

Further, the shaping optical path is a beam expanding optical path with the magnification of 1-8 times.

Further, the single pulse width is 1-15 ps.

Further, the laser wavelength emitted by the laser is set to be 266 +/-5 nm; the advancing speed of the laser facula is 1-500 mm/s.

The invention also comprises a system for realizing the deep ultraviolet ultrafast laser sapphire cutting method, wherein the system comprises a workbench, an optical system and a main control system, and the main control system is arranged on one side of the workbench;

the optical system comprises a deep ultraviolet ultrafast laser, a light path and a laser cutting head;

the workbench is provided with an upright post, the upright post is also provided with a first drive and a first track, a first sliding block is arranged in the first track, and the first drive can drive the first sliding block to move up and down in the first track; the first slider is provided with a second track and a second drive, the second track is internally provided with a second slider, and the second drive can drive the second slider to horizontally move in the second track; the second sliding block is provided with a laser cutting head;

the worktable is also provided with a fixing device, and the fixing device is fixedly used for clamping a sapphire workpiece to be cut;

the main control system is respectively connected with the optical system and the workbench; the laser is connected with a computer controller provided with laser cutting system software through a data line, the computer controller inputs controlled laser parameters, scanning speed and repetition frequency signals into the laser, receives pulse synchronous signals of the laser, and controls a light path, a first driver, a second driver and a workbench to complete laser cutting of the sapphire workpiece.

Further, fixing device includes the fixed station, be equipped with the platform of lifting on the fixed station, one side of platform of lifting is equipped with the fixed block, the opposite side of platform of lifting is equipped with flexible clamp plate.

Furthermore, an ultrasonic thickness sensor is arranged on the fixing block.

Furthermore, a moving distance sensor is arranged on the laser cutting head.

Preferably, the main control system is respectively connected with the ultrasonic thickness sensor and the moving distance sensor.

The frequency-locked uniform energy single-pulse ultrafast laser provided by the invention has the working mode of the ultrafast laser that the uniform energy single-pulse is periodically output under the locking frequency.

The invention has the beneficial effects that:

1. the invention cuts sapphire based on the locking ultrafast laser cutting method with high repetition frequency, single-pulse work, high single-pulse energy and high single-pulse energy consistency, and has good photon consistency and high cutting precision.

2. The method provided by the invention can be used for cutting the sapphire wafer, has good single-pulse uniformity, high processing speed and good notch quality, almost has no adhering slag, and can be used for cutting any pattern. The single pulse power density can be as high as 10¹²W/cm²In the above, the material in the laser-active region is instantaneously evaporated or vaporized, and a saturated processing length is hardly formed in the sapphire material.

3. The invention is based on the locked ultrafast laser cutting method with high repetition frequency, high single pulse energy and high single pulse energy consistency, the sapphire workpiece is cut, the consistency of the processing process is good, the cutting precision is greatly higher than that of the traditional ultrafast laser cutting method, and the requirements can be met without the treatment of splintering and the like at the later stage.

4. According to the laser cutting method, the high-energy single pulse output by the laser device is unique in time domain, the specific position point of the processed workpiece is very accurate, the workpiece cannot drift in space, and the cutting precision is further improved.

5. The cutting method has the advantages of uniform and accurate pulse, short processing time, almost no missing point and accurate time sequence matching.

6. The method realizes cutting by the ultrafast laser vaporization material processing surface with high single pulse energy, but not by the action of melting by heat, so that the method hardly has the phenomena of a heat affected zone, and the processing surface hardly has slag adhering, cracks, edge breakage and the like.

7. Under the irradiation of the ultrafast laser equipment with high single pulse energy consistency, the surface of a workpiece is clear and bright, repeated irradiation is avoided, the material is hardly darkened, and the characteristic parameters of the material are hardly changed.

Description of the drawings:

FIG. 1 is a schematic structural diagram of a deep ultraviolet ultrafast laser sapphire cutting system according to the present invention;

FIG. 2 is a schematic structural diagram of a fixed table in the DUV ultrafast laser sapphire cutting system of FIG. 1;

FIG. 3 is a schematic diagram of a deep ultraviolet ultrafast laser sapphire cutting method according to the present invention;

FIG. 4 is a photograph showing the cutting effect of the method for cutting sapphire by deep ultraviolet ultrafast laser according to the present invention;

wherein: 1-stage, 2-stage, 3-fixture, 31-fixture, 32-elastic compression plate, 33-lift stage, 34-ultrasonic thickness sensor, 35-fixture, 4-main control system, 5-column, 6-first rail, 7-first drive, 8-first slider, 9-second rail, 10-second drive, 11-second slider, 12-optical system, 121-laser, 122-shaping optical path, 123-beam transmission optical path, 1231-mirror group, 1232-single mirror, 13-moving distance sensor, 14-laser cutting head, 15-laser carrying box.

Detailed Description

The method and system for deep ultraviolet ultrafast laser sapphire cutting according to the present invention will be further explained with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to the following embodiments.

A method of deep ultraviolet ultrafast laser sapphire dicing, the method comprising the steps of:

1) fixing a sapphire workpiece on a workbench 1 through a fixing device 3;

2) laser emitted by a laser 121 is focused on the surface of a sapphire workpiece on a workbench 1 after sequentially passing through a shaping light path 122, a light beam transmission light path 123 and a laser cutting head 14; the laser cutting head 14 is arranged above the sapphire through a driving system;

3) the laser is a deep ultraviolet ultrafast laser capable of emitting single pulse with frequency locking and uniform energy; the emission frequency of the laser is a certain value between 50KHz and 100 KHz; the single pulse energy emitted by the laser is 200uJ-400uJ, and the consistency of the single pulse energy is less than or equal to +/-5 percent

4) Cutting of the sapphire workpiece is accomplished by controlling the speed of travel of the laser beam of laser cutting head 14 about the axis of sapphire workpiece surface X, Y, Z.

The invention also comprises a system for realizing the deep ultraviolet ultrafast laser sapphire cutting method, wherein the system comprises a workbench 1, an optical system 12 and a main control system 4, and the main control system 4 is arranged on one side of the workbench;

the optical system 12 comprises a deep ultraviolet ultrafast laser 121,

optical paths

122 and 123 and a laser cutting head 14;

an upright post 5 is arranged on the workbench 1, a first drive 7 and a first track 6 are further arranged on the upright post 5, a first slide block 8 is arranged in the first track 6, and the first drive 7 can drive the first slide block 8 to move up and down in the first track 6; a second track 9 and a second drive 10 are arranged on the first sliding block 8, a second sliding block 11 is arranged in the second track 9, and the second drive 10 can drive the second sliding block 11 to horizontally move in the second track 9; the second sliding block 11 is provided with a laser cutting head 14;

the worktable 1 is also provided with a fixing device 3, and the fixing device 3 is fixedly used for clamping a sapphire workpiece to be cut;

the main control system 4 is respectively connected with the optical system 12 and the workbench 1; the laser 121 is connected with a computer controller 4 provided with laser cutting system software through a data line, the computer controller 4 inputs controlled laser parameters, scanning speed and repetition frequency signals to the laser 121, receives pulse synchronization signals of the laser 121, and controls

light paths

122 and 123, the first driver 7 and the second driver 10 to complete laser cutting of the sapphire workpiece.

Further, fixing device 3 includes fixed station 2, be equipped with lifting table 33 on the fixed station 2, one side of lifting table 33 is equipped with fixed block 35, the opposite side of lifting table 33 is equipped with elasticity compression board 32.

Further, an ultrasonic thickness sensor 34 is disposed on the fixing block 35.

Further, a moving distance sensor 13 is arranged on the laser cutting head 14.

Preferably, the main control system 4 is connected with the ultrasonic thickness sensor 34 and the moving distance sensor 13, respectively.

Example 1

The structure of the system for cutting sapphire by deep ultraviolet ultrafast laser in the embodiment is as follows:

as shown in fig. 1-2, the system includes a workbench 1 and a main control system 4, the main control system is a computer, and the main control system 4 is disposed at one side of the workbench 1;

the workbench 1 is also provided with an upright post 5, the upright post 5 is provided with a first drive 7 and a first track 6, a first slide block 8 is arranged in the first track 6, and the first drive 7 is used for driving the first slide block 8 to move up and down in the first track 6; the first sliding block 8 is provided with a second track 9 and a second drive 10, a second sliding block 11 is arranged in the second track 9, and the second drive 10 can drive the second sliding block 11 to horizontally move in the second track 9; the second slide block 11 is provided with a laser cutting head 14; a moving distance sensor 13 is arranged on the laser cutting head 14;

the laser cutting machine comprises a laser cutting head 14, a workbench 1, a fixing device 3, a lifting table 33, a fixing block 35, a telescopic pressing plate, a fixing plate 31 and an elastic compression plate 32, wherein the workbench 1 below the laser cutting head 14 is provided with the fixing device 3, the fixing device 3 comprises the fixing table 2, the lifting table 33 is arranged on the fixing table 2, one side of the lifting table 33 is provided with the fixing block 35, the other side of the lifting table 33 is provided with the telescopic pressing plate, the telescopic pressing plate comprises the fixing plate 31 and the elastic compression plate 32, the fixing plate 31 is fixed on the fixing table 2, and the elastic compression plate 32 is elastically connected with the fixing plate 31; placing the sapphire on the lifting table 33, and clamping and fixing the sapphire on the lifting table 33 by the fixing block 35 in cooperation with the telescopic pressing plate; the fixed block 35 is also provided with an ultrasonic thickness sensor 34;

wherein optical system 12 includes laser 121, shaping optical path 122, beam delivery optical path 123, and cutting head 14; the shaping optical path 122 is a beam expanding optical path with 5 times of magnification; the transmission distance of the light beam transmission light path 123 is 600mm, and the light beam transmission light path 123 comprises a reflector set 1231 and a single reflector 1232 which changes the light path transmission direction, which are arranged oppositely; the laser cutting head 14 with focusing function focuses laser and then emits the focused laser on the sapphire below;

wherein the laser 121 is placed in the laser carrier case 15;

the main control system 4 is respectively connected with the all-solid-state picosecond laser 121, the

optical paths

122 and 123, the first drive 7 and the second drive 10;

the main control system 4 is connected to the ultrasonic thickness sensor 34 and the movement distance sensor 13, respectively.

The main control system 4 is also connected with a lifting platform 33 and controls the lifting distance of the lifting platform 33;

in the present invention, the first and second drives 7 and 10 may be air cylinders, or any one disclosed in the related art can have a structure having the same function.

The working method of the cutting system of the laser cutting system of the embodiment is as follows:

1) the sapphire is placed on the lifting table 33, and the fixed blocks 35 and the telescopic pressing plates on the two sides respectively clamp and fix the sapphire from the two sides;

2) setting laser parameters of the all-solid-state picosecond laser 121; wherein, the laser emission frequency is 100 KHz; the energy of the emitted single pulse is 200uJ, the width of the single pulse is 15ps, and the consistency of the energy of the single pulse is less than or equal to +/-5%; the window light spot of the laser is 2mm, the divergence angle is 0.9mrad, and the advancing speed of the laser light spot is 1-500 mm/s.

3) The main control system 4 calculates the cut thickness through the thickness of the sapphire detected by the ultrasonic thickness sensor 34, thereby setting the moving distance of the first driver 7 and the second driver 10;

4) the laser cutting head 14 is driven by the first drive 7 and the second drive 10 to move along a set movement distance to cut, and the movement distance sensor 13 detects the actual movement distance.

The cutting effect is shown in fig. 4.

Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can make modifications and equivalents to the embodiments of the present invention without departing from the spirit and scope of the present invention, which is set forth in the claims of the present application.

Claims

1. A deep ultraviolet ultrafast laser sapphire cutting method is characterized by comprising the following steps:

1) fixing the sapphire workpiece on a workbench through a fixing device;

3) the laser is a deep ultraviolet ultrafast laser capable of emitting single pulse with frequency locking and uniform energy; the emission frequency of the laser is a certain value between 50KHz and 100 KHz; the energy of single pulses emitted by the laser is 200uJ-400uJ, and the energy difference between the single pulses is less than or equal to +/-5%;

2. The method of claim 1, wherein the laser is an all-solid-state picosecond laser.

3. The deep ultraviolet ultrafast laser sapphire cutting method as claimed in claim 1, wherein a window spot of said laser is 1-3mm, and a divergence angle is 0.5-1.5 mrad.

4. The method as claimed in claim 1, wherein the transmission distance of the beam transmission path is 200-1000 mm.

5. The method according to claim 1, wherein the shaping optical path is a beam expanding optical path with a magnification of 1-8 times.

6. The deep ultraviolet ultrafast laser sapphire cutting method as claimed in claim 1, wherein the single pulse width is 1-15 ps.

7. The deep ultraviolet ultrafast laser sapphire cutting method as set forth in claim 1, wherein a laser wavelength emitted from the laser is set to 266 ± 5 nm; the advancing speed of the laser facula is 1-500 mm/s.

8. The system for realizing the deep ultraviolet ultrafast laser sapphire cutting method of claim 1, wherein the system comprises a workbench, an optical system and a main control system, and the main control system is arranged on one side of the workbench;

9. The system of claim 8, wherein the fixing device comprises a fixed table, a lifting table is arranged on the fixed table, a fixed block is arranged on one side of the lifting table, and a telescopic pressing plate is arranged on the other side of the lifting table.

10. The system of claim 9, wherein the fixed block is provided with an ultrasonic thickness sensor.