CN112620960A

CN112620960A - Processing method for sapphire front etching assisted by metal oxide coating

Info

Publication number: CN112620960A
Application number: CN202011550882.0A
Authority: CN
Inventors: 杨富理; 袁根福; 李�浩
Original assignee: Jiangnan University
Current assignee: Jiangnan University
Priority date: 2020-12-24
Filing date: 2020-12-24
Publication date: 2021-04-09

Abstract

The invention belongs to the application field of special processing, in particular to a processing method for sapphire by using a metal oxide coating to assist laser front etching, which can realize continuous etching with higher etching rate and comprises the following steps: (1) determining the type and the particle diameter of the metal oxide, the thickness and the component ratio of the coating; (2) coating a uniform metal oxide coating on the surface of the sapphire; (3) determining technological parameters of a laser system; (4) determining a laser scanning path and a scanning speed; (5) the laser etches according to the scanning path.

Description

Processing method for sapphire front etching assisted by metal oxide coating

Technical Field

The invention belongs to the application field of special processing, and particularly relates to a processing method for sapphire by using a metal oxide coating to assist laser front etching.

Background

Sapphire has excellent physical and chemical properties and is an important material in the microelectronics, optoelectronics, optics and optical fiber industries. The sapphire crystal has the characteristics of good light transmission, high transmittance of more than 85% in ultraviolet and infrared bands, high melting point, high hardness, good heat conductivity, stable chemical property and the like, and has wide application in the fields of superconduction, photoelectron, microelectronics, national defense and the like. With the development of modern science and technology, the processing precision and the surface quality of the transparent crystal sapphire have very high requirements. Because sapphire belongs to hard and brittle materials, phenomena such as cracks, edge breakage and the like are easy to occur in the traditional machining process. And because the sapphire has better chemical stability, the sapphire is difficult to process by a chemical processing method. The method has the advantages of low processing efficiency, high processing cost, low processing precision and difficult realization of automation, and limits the development of the transparent crystal processing technology.

The laser etching technology is a processing method without contact, cutting force and heat influence, and has the advantages of excellent processing quality, high efficiency, wide processing range, good economic benefit and the like. The micro-machining method can be used for micro-machining of hard and brittle materials, can be combined with a numerical control technology, can realize flexible manufacturing, and accords with the future development trend. After the laser is focused by the lens, a laser beam with the diameter of several micrometers can be formed, so that high energy density is achieved, and a strong thermal effect can be generated after the laser beam meets a processed material, so that the material can be etched. The laser processing is a high-speed and high-quality processing technology and has the characteristics of high processing speed, narrow cutting seams and grooves, smooth section, neat cutting edges, small heat affected zone, high material applicability and the like. However, due to the high transmittance of sapphire, the etching operation cannot be completed by a general low-cost infrared laser.

Disclosure of Invention

In order to solve the problem that the sapphire cannot be etched by a low-cost infrared laser due to overhigh light transmittance, the invention provides a processing method for etching sapphire on the front surface by using metal oxide coating assisted laser, which can realize continuous etching with high etching rate.

The technical scheme is as follows: a processing method for sapphire front etching assisted by a metal oxide coating is characterized by comprising the following steps:

(1) determining the type and the particle diameter of the metal oxide, the thickness and the component ratio of the coating;

(2) coating a uniform metal oxide coating on the surface of the sapphire;

(3) determining technological parameters of a laser system;

(4) determining a laser scanning path and a scanning speed;

(5) the laser etches according to the scanning path.

It is further characterized in that the laser scanning path is linear or circular.

After the method is adopted, the uniform and compact metal oxide coating is coated on the surface of the sapphire, the laser is prevented from directly transmitting the transparent crystal, the laser energy is transmitted to the transparent crystal through the coating for etching, and compared with other materials such as salt, acid, alkali and the like, the metal oxide has higher absorption rate to the laser, and the continuous etching with higher etching rate is realized.

Drawings

FIG. 1 is a diagram of the structure of the apparatus required for the processing method of the present invention, in which: 1. a laser processing platform; 2. a sapphire crystal sample; 3. a metal oxide coating; 4. a focusing lens; 5. a laser beam; 6. a light-reflecting lens; 7, a laser head;

FIG. 2 is a flow chart of a processing method for performing laser front etching sapphire assisted by a metal oxide coating according to the present invention;

FIG. 3 shows a laser scanning path implemented in the present invention as a circular path, wherein: 1. a scan path starting point; 2. a scan path end point;

FIG. 4 shows a laser scanning path implemented in the present invention as a linear path, wherein: 1. a scan path starting point; 2. end point of scan path.

Detailed Description

In order to clearly show the technical scheme of the invention, reasonable metal oxide coating parameters and laser system processing parameters are selected in combination with the attached drawings, and the invention is further explained.

Referring to fig. 2, a processing method for laser front etching sapphire assisted by metal oxide coating includes the following steps:

(1) determining the type and the particle diameter of the metal oxide, the thickness and the component ratio of the coating

The aggregate of the coating is 41 percent of TiO2, the particle diameter is 50nm, the binder is 22 percent of PAI, the diluent is deionized water, and the thickness of the coating is 0.1 mm.

(2) Spraying a uniform and compact metal oxide coating on the surface of the sapphire crystal;

and uniformly coating the prepared coating on the surface of the transparent crystal by blade coating.

(3) Determining technological parameters of a laser system;

and (3) turning on the laser, wherein the output power of the laser is 13w, the pulse width is 100ns, the pulse frequency is 30KHZ, the defocusing amount is 0mm, the processing speed is 5mm/s, and the processing times are 3 times.

(4) Determining a laser scanning path and a scanning speed;

the laser scanning speed was chosen to be 5mm/s and the scanning path was either straight, as shown in fig. 4, or circular, as shown in fig. 3. Fig. 4 shows a linear scan path specifically: and after the laser longitudinally runs through the straight line, the laser is turned off, the laser is transversely fed for one line spacing, then the laser is turned on to scan again, and the process is repeated until the scanning is finished. The circular path of fig. 3 is embodied as: and scanning the laser from outside to inside, turning off the laser after the outermost ring is scanned, transversely feeding the laser for one line spacing, starting the laser to scan again, and repeating the steps until the scanning is finished.

(5) The laser is etched according to the scanning path

Starting laser for processing

And finishing the processing process.

The maximum output power of laser is 20w, the pulse width is 100ns, the diameter of a light spot is 30 micrometers, the pulse repetition frequency is 20-100 KHz, the defocusing amount is-2 to +2mm, the laser scanning speed is 3-7 mm/s, the processing times are 1-5 times, the aggregate of the coating is TiO2(20% -48%), the particle diameter is less than 2 micrometers, the binder is PAI (9% -29%), the diluent is deionized water, and the thickness of the coating is 0.1-0.5 mm.

The average notch width of 33 μm and the notch depth of 12.8 μm were experimentally obtained at a particle diameter of 2 μm, an aggregate TiO2 content of 48%, a binder content of 19%, and a coating thickness of 0.3mm at an output of 11w, a frequency of 20kHZ, and a scanning speed of 5 mm/s. The average notch width of 37 μm and the notch depth of 16.8 μm were experimentally obtained at a particle diameter of 50nm, an aggregate TiO2 content of 41%, a binder of 22%, and a coating thickness of 0.1mm at an output power of 12w, a frequency of 20kHZ, and a scanning speed of 5 mm/s. Preliminary experiments have shown that the smaller the particle diameter, the greater the depth and width of the groove.

To further understand the effect of the absorber layer parameters on the etching of sapphire, an orthogonal test method can be used. The orthogonal test was performed using a three-factor five-level test, with factor 1 coating thicknesses of 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, factor 2 aggregate content of 20%, 27%, 34%, 41%, 48%, and factor 3 binder content of 9%, 14%, 19%, 24%, 29%. And (5) carrying out 25 times of experiments, comparing the depth and width of the notch groove and the notch groove appearance after the experiments are finished, and optimizing a group of optimal parameters so as to obtain optimal absorption layer parameters.

The laser parameter output power, repetition frequency, scanning speed and scanning times can be researched by adopting a single-factor method, so that the optimal laser parameter is selected. Other parameters are fixed, the output power is 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% and 100%, and the etching results are compared to select the optimal output power. Other parameters are fixed, the repetition frequency is 20kHz, 25kHz, 30kHz, 35kHz and 40kHz, and the optimal repetition frequency is selected by comparing etching results. Scanning speeds of 1mm/s, 3mm/s, 5mm/s, 7mm/s, 9mm/s, 11mm/s, 13mm/s and 15mm/s, and comparing the etching results to select the optimal scanning speed. Other parameters are fixed, the scanning times are 1 time, 2 times, 3 times, 4 times, 5 times, 6 times, 7 times and 8 times, etching results are compared, and the optimal scanning times are selected, so that the optimal laser parameters are obtained.

The micro-groove etching on the surface of the sapphire crystal can be completed through the steps, and the transparent crystal is assisted by the metal oxide coating to absorb laser energy, so that the etching efficiency is improved, and the processing cost is reduced.

The invention has the following beneficial effects:

(1) the uniform metal oxide coating is coated on the sapphire, so that the absorption rate of the sapphire to laser can be improved, the laser is prevented from directly penetrating through the sapphire crystal, the energy loss of the laser is reduced, and the laser beam is directly etched on the surface of the sapphire crystal.

(2) The front surface is directly etched, and grooves with good processing surface quality are etched on the surface of the sapphire.

(3) The invention has simple process, convenient operation and low cost.

(4) The invention can realize the etching of any two-dimensional graph through computer programming.

Claims

1. A processing method for sapphire front etching assisted by a metal oxide coating is characterized by comprising the following steps:

(2) coating a uniform metal oxide coating on the surface of the sapphire;

(3) determining technological parameters of a laser system;

(4) determining a laser scanning path and a scanning speed;

(5) the laser etches according to the scanning path.

2. The method as claimed in claim 1, wherein the laser scanning path is linear or circular.