CN113387601A

CN113387601A - Method for improving glass welding strength with assistance of high-vacuum magnetron sputtering interface

Info

Publication number: CN113387601A
Application number: CN202110596430.4A
Authority: CN
Inventors: 林奈; 王聪; 张世福
Original assignee: Southwest Electronic Technology Institute No 10 Institute of Cetc
Current assignee: CETC 10 Research Institute; Southwest Electronic Technology Institute No 10 Institute of Cetc
Priority date: 2021-05-31
Filing date: 2021-05-31
Publication date: 2021-09-14

Abstract

The method for improving the welding strength of the glass by the aid of the high-vacuum magnetron sputtering interface disclosed by the invention has the advantages of stable welding quality, good appearance of a welding seam and high welding yield. The invention is realized by the following technical scheme: arranging a total reflector with a 45-degree inclined plane at the front end of the high repetition frequency ultrafast laser, and forming a reverse U-shaped light path by overlooking the total reflector according to a splay with 45-degree inclined distribution and mirror symmetry; the ultra-short pulse light beam is transmitted to a 45-degree overlooking total reflector at the tail end of a reverse U-shaped light path through the total reflector and is transmitted to a diaphragm, the size of a light spot is adjusted through the diaphragm, the light spot is focused to the interface of two superposed glass sheets to be welded fixed on a positioning clamp of an electric control three-dimensional motion platform through a lens, the laser beam penetrates through a metal film clamped on the superposed glass sheets to be welded and the superposed glass sheets to be welded, a generated peak cone light wire passes through a preset two-dimensional scanning track to generate a molten pool with a nonlinear absorption effect on the focus interface of the metal film scanning track, and a compact welding line is formed after cooling.

Description

Method for improving glass welding strength with assistance of high-vacuum magnetron sputtering interface

Technical Field

The invention belongs to the technical field of laser welding, and relates to a laser welding system which utilizes a special laser beam as a local hot processing technology of a heat source and deposits a nanometer-thickness film on the surface of glass through high-vacuum magnetron sputtering to improve the welding strength.

Background

With the development of the fields of micro-electro-mechanical systems (MEMS), novel sensors, aerospace, and the like, the fields often need to connect glass components together, for example, in the field of novel sensors, the connection of the optical fiber end cap and the optical fiber end face can play roles of enhancing the damage threshold of components, protecting, sealing, and the like, and in addition, fresnel reflection can be reduced, the air holes of a super-continuum spectrum generated in the microstructure optical fiber can be sealed, and the further degradation of the components due to the diffusion of hydroxyl groups in the glass can be avoided; in the preparation of the microfluidic chip, for a complex three-dimensional microfluidic channel, a micro-groove can be etched in each piece of glass, and then the pieces of glass are connected together to form a three-dimensional channel structure, wherein the pieces of glass need to be connected together. The requirements for glass connection in these fields are becoming more and more stringent, and the demands for high-strength and high-reliability connection between glasses are urgent, so that high-strength connection between glasses is a problem to be solved urgently.

Currently, the commonly used glass connection methods include adhesive connection, optical bonding connection, anodic bonding, and the like. Adhesive bonding is generally a technique for achieving bonding between objects by using a curing reaction process of an organic or inorganic adhesive. The bonding technology has the advantages of relatively simple operation process, high connection efficiency and wide application material range, but has the defects of easy aging, easy photobleaching, toxic and harmful gas release, environmental pollution and the like, and is difficult to use under severe conditions of high temperature, high load and the like. Anodic bonding means that polished glass and semiconductors are closely attached together, direct current of 200-2000 volts is introduced at 300-500 ℃, and connection can be completed after the current is stabilized and then slowly cooled to room temperature. Anodic bonding is widely applied in the field of microfluidics and micro-electromechanical manufacturing due to the advantages of firm bonding interface, good long-term stability and the like, but the thermal expansion coefficients of two bonding materials are required to be similar, otherwise the successful connection is difficult.

With the rapid development of laser technology, lasers are widely used for welding various materials. The glass is used as a transparent fragile brittle material, a traditional laser light source cannot be easily absorbed by the glass, and the glass absorbing heat is formed by the fact thatDifferent parts have different thermal expansion degrees, and are easy to break during welding, so that the processing is difficult to be carried out by the traditional laser welding mode. At present, two methods are mainly used for laser welding of transparent materials such as glass and the like. One method is to add an intermediate absorption layer at a welding interface, the intermediate absorption layer absorbs laser energy and increases the temperature, then the energy is transmitted to a material in a heat conduction mode, and the material is melted and then solidified to realize the connection of the transparent material. This method can produce a large amount of porosity in the weld which affects the weld strength, and in addition, it can produce a large heat affected zone that is not suitable for precise joining of glass. The other method is to adopt a special welding light source for welding, high-power-density laser is acted with a transparent material through a nonlinear absorption effect to form an effective welding spot, and more researchers and engineers look to laser welding processing application of the special light source. The special laser welding processing utilizes a laser beam with high power density, and after the laser beam is focused by an optical system, the power density of a laser focus is about 10⁴～10⁷W/cm²The workpiece is heated and melted near the laser focus, and the melting phenomenon and the strength of the melting phenomenon are mainly determined by the time of the laser acting material and the laser parameters. In recent years, the same type of glass, and single crystal silicon are successively welded by using a special light source. The U.S. PolaOnyx company uses special laser single/multi-line scanning to realize glass welding and sealing. The Herlie et al used a special laser to micro-weld a 100 μm thick glass end cap to a microstructured optical fiber, successfully welding the end caps to standard and microstructured optical fibers. Tamaki et al used laser with a wavelength of 1558nm in research to successfully realize welding between dissimilar glasses and between glass and silicon wafers, and respectively obtained welding strengths of 9.87MPa and 3.74 MPa.

For example, chinese patent publication No. CN106449439A proposes to perform welding and packaging on a glass chip by using picosecond laser, and uses the characteristic that picosecond laser can directly generate a nonlinear process with glass, so as to melt the glass and then cool the glass to realize welding of the glass. The method can avoid excessive heat accumulation, prevent the glass material from being broken due to overheating, and has higher processing precision. For another example, patent CN108609841A proposes to perform welding operation on glass with picosecond laser, which overcomes various defects of long pulse laser welding glass, and realizes glass welding under large gap by cooperating with scanning galvanometer system and appropriate laser parameters.

Although the above method realizes the welding of glass, there is a problem that the laser energy absorption rate is low, and the welding strength is difficult to meet the demand of industrial products, and further improvement is demanded.

Disclosure of Invention

The method aims to overcome the defects that the traditional laser cannot directly weld transparent materials such as glass and the like, and the problems of low welding strength, unstable welding quality, poor welding seam quality and low energy absorption rate in ultra-fast laser welding. The invention provides a micro-welding method which has stable welding quality, good welding seam appearance, high welding yield, and is easy to realize high strength and high precision of glass.

The present invention achieves the above object by the following technical means. A method for improving glass welding strength by the aid of a high-vacuum magnetron sputtering interface is characterized by comprising the following steps: a total reflector 2 with an inclined surface of 45 degrees is arranged at the front end of a high-repetition-frequency ultrafast laser 1 of equipment required by welding, and a reverse U-shaped light path is formed by overlooking the total reflector according to a splay shape which is distributed in a mirror symmetry manner along the inclined surface of the total reflector 2 and is vertical to the upper part of the light path; the method comprises the steps that an electric control three-dimensional motion platform 3 and an ultra-short pulse light beam generated by a high repetition frequency ultra-fast laser 1 are transmitted to a 45-degree overlooking total reflector at the tail end of a reverse U-shaped light path through a total reflector 2, the ultra-fast laser beam 8 emitted vertically downwards is transmitted to a diaphragm 10, the size of a light spot is adjusted through the diaphragm 10, the light spot is focused to the interface of two superposed glass sheets to be welded 4 fixed on a positioning clamp of the electric control three-dimensional motion platform through a focusing mirror 9, the ultra-fast laser beam 8 penetrates through a metal film 5 clamped on an upper superposed glass sheet to be welded 6 and a lower superposed glass sheet to be welded 4, a peak cone light wire 7 generated by the ultra-fast laser passes through a preset two-dimensional scanning track, a molten pool with a nonlinear absorption effect is generated on the scanning track interface of the metal film 5, and a compact welding seam is formed after cooling.

Compared with the prior art, the invention has the following beneficial effects:

the invention adopts a high repetition frequency ultrafast laser 1 to generate an ultrafast pulse beam, the transmission direction of the beam is changed by a holophote 2, the ultrafast pulse beam is reflected to a holophote with 45 degrees at the tail end, the ultrafast laser beam 8 vertically emitted downwards is transmitted to a diaphragm 10, the size of a light spot is adjusted by the diaphragm 10, and the beam is focused to the interface of two superposed glass sheets fixed on a positioning clamp of an electric control three-dimensional moving platform by a focusing mirror 9.

The invention uses the lens instead of the objective lens for focusing, can generate the peak conical light wire with the length of hundreds of microns at most in the glass, and the peak conical light wire is arranged at the interface, thereby effectively reducing the focusing difficulty. The welding automation degree is high, the welding can be controlled by a computer, the welding speed is high, the efficiency is high, and the welding of any complex shape can be conveniently carried out; the laser welding heat affected zone is small, the material deformation is small, and the subsequent process treatment is not needed.

According to the invention, a metal film with a nanometer thickness is plated between two pieces of glass by using a high-vacuum magnetron sputtering system, so that ultrafast laser can generate a linear absorption effect at a focus, the absorption rate of laser energy is increased, a molten pool with a larger and more uniform volume is formed at the focus by combining the heat accumulation effect of high-repetition-frequency ultrafast laser, and the glass can be welded together after cooling to form a more compact and stable welding line, thereby effectively improving the welding strength of the glass and the utilization rate of the laser energy. The problems that the glass can not be welded by common continuous laser and the glass is low in strength by ultrafast laser welding are solved. And the laser energy utilization rate of the ultra-fast laser welding glass is improved. The length of the generated peak cone light wire reaches hundreds of microns, the focusing difficulty is reduced, the ultra-fast laser welding glass technology is favorably applied in an engineering way, the practicability is stronger, and the popularization and the application are favorably realized.

The invention adopts high vacuum magnetron sputtering to plate metal nano-film on the glass interface, thereby improving the glass welding strength, and compared with the metal film assistance and the metal film-free assistance, when the metal film assistance is provided, the welding seam is more uniform and consistent, the formed molten pool is larger, and the condition of heat affected zone disconnection does not occur. In addition, the utilization rate of laser energy is greatly improved when the metal film is added for assistance.

According to the invention, the metal film with the nanometer thickness is plated at the interface of the glass, so that the welding seam can be melted more uniformly under the assistance of the metal film, a molten pool with a larger volume is generated in the processing process, the cooled welding seam is more uniform, and the welding strength of the glass is improved. The addition of the metal film also increases the absorptivity of the laser and improves the utilization rate of the laser energy. The glass is welded by using the peak cone bright wire generated after the lens is focused, and the length of the peak cone bright wire can be hundreds of microns, so that the focusing difficulty can be effectively reduced, and the industrial application of the laser welding glass is further promoted. The method has the advantages of promoting the ultra-fast laser welding glass technology to be applied industrially and improving the practical value of the technology.

Drawings

FIG. 1 is a schematic view of a special laser welding system of the present invention for improving glass weld strength;

FIG. 2 is a comparison of the inventive (left) weld with other (right) welds;

wherein: 1-high repetition frequency ultrafast laser, 2-holophote, 3-electric control three-dimensional motion platform, 4-lower glass sheet to be welded, 5-metal film, 6-upper glass sheet to be welded, 7-ultrafast laser filament, 8-ultrafast laser beam, 9-focusing mirror and 10-diaphragm.

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments.

Detailed Description

See fig. 1. According to the invention, a total reflector 2 with an inclined surface of 45 degrees is arranged at the front end of a high repetition frequency ultrafast laser 1 of equipment required by welding, and a reverse U-shaped light path is formed by overlooking the total reflector according to a splay with 45-degree inclined distribution and mirror symmetry above a vertical light path along the inclined surface of the total reflector 2; the method comprises the steps that an electric control three-dimensional motion platform 3 and an ultra-short pulse light beam generated by a high repetition frequency ultra-fast laser 1 are transmitted to a 45-degree overlooking total reflector at the tail end of a reverse U-shaped light path through a total reflector 2, the ultra-fast laser beam 8 emitted vertically downwards is transmitted to a diaphragm 10, the size of a light spot is adjusted through the diaphragm 10, the light spot is focused to the interface of two superposed glass sheets to be welded 4 fixed on a positioning clamp of the electric control three-dimensional motion platform through a focusing mirror 9, the ultra-fast laser beam 8 penetrates through a metal film 5 clamped on an upper superposed glass sheet to be welded 6 and a lower superposed glass sheet to be welded 4, a peak cone light wire 7 generated by the ultra-fast laser passes through a preset two-dimensional scanning track, a molten pool with a nonlinear absorption effect is generated on the scanning track interface of the metal film 5, and a compact welding seam is formed after cooling.

Two glass samples are stacked and fixed on an electric control three-dimensional motion platform, and the position of the three-dimensional platform is adjusted to enable a laser focus to be arranged at the interface of the two glass samples, so that a peak cone light wire 7 is generated at the moment, namely, the peak cone light wire 7 is arranged at the metal film 5; and adjusting appropriate processing parameters to process according to a preset scanning track, and welding the two glass samples together. The electric control three-dimensional motion platform can move in a three-dimensional space in any track under the control of the controller. The lower glass sheet 4 to be welded can be coated with a metal film 5 by a high vacuum magnetron sputtering system, the upper glass sheet 6 to be welded can be uncoated, and the metal film 5 is coated on the lower glass sheet 4 to be welded. The gap between the lower glass sheet to be welded 4 and the upper glass sheet to be welded 6 is less than 1 micron. In order to ensure that two glass sheet samples to be welded do not fall off after welding, the total welding area is more than or equal to 1 square millimeter.

In alternative embodiments: the laser emitted by the ultrashort pulse laser is near infrared light, the wavelength of the laser is 1030nm, the pulse width is 215fs, the repetition frequency is 75kHz-615kHz, and the average power is 1W-10W. The lower glass sheet 4 to be welded and the upper glass sheet 6 to be welded are two quartz glass sheets, a high vacuum magnetron sputtering system is utilized to plate a nickel film with the thickness of 50nm to 100nm on one side, the scanning speed is 1000 mu m/s to 2000 mu m/s, the scanning is in a shape like a Chinese character ji, the line spacing is 50 mu m to 200 mu m, and the scanning area is 1 multiplied by 1mm²-10×10mm². The test results show that the shear force is increased from around 100N to around 350N as the parameters are changed. The weld strength is greatly reduced when the metal film is removed, which can lead to cracking of the sample when the laser parameters are inappropriate.

In alternative implementationsIn the examples: the laser emitted by the ultrashort pulse laser is near infrared light, the wavelength of the laser is 1030nm, the pulse width is 215fs, the repetition frequency is 615kHz, and the average power is 2W-6W. The processed sample is two pieces of quartz glass, a silver film with the thickness of 50nm is plated on one side of the sample by utilizing a high vacuum magnetron sputtering system, the scanning speed is 1000 mu m/s, the sample is scanned in a shape like a Chinese character ji, the line spacing is 50 mu m, and the scanning area is 1 multiplied by 1mm². The test shows that the welding strength is about 70MPa-90 MPa, the welding strength is about 50MPa-70MPa for the sample without the silver coating, and when the welding condition is put without the assistance of the metal film and the gap between the two glasses is enlarged to be more than ten microns, the welding strength is further reduced to 20MPa-50 MPa.

The above detailed description of the embodiments of the present invention, and the detailed description of the embodiments of the present invention used herein, is merely intended to facilitate the understanding of the methods and apparatuses of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims

1. A method for improving glass welding strength by the aid of a high-vacuum magnetron sputtering interface is characterized by comprising the following steps: a total reflector (2) with a 45-degree inclined plane is arranged at the front end of a high-repetition-frequency ultrafast laser (1) of equipment required by welding, and a reverse U-shaped light path is formed by overlooking the total reflector according to a splay with 45-degree inclined distribution and mirror symmetry above a vertical light path along the inclined plane of the total reflector (2); an electric control three-dimensional motion platform (3), an ultrashort pulse light beam generated by a high repetition frequency ultrafast laser 1, the direction is changed by the holophote (2) and transmitted to the 45-degree overlooking holophote at the tail end of the reverse U-shaped light path, the ultrafast laser beam (8) emitted vertically downwards is transmitted to the diaphragm (10), the size of light spots is adjusted through a diaphragm (10), and then the light spots are focused to the interface of two superposed glass sheets to be welded fixed on a positioning fixture of an electric control three-dimensional motion platform through a focusing mirror (9), an ultrafast laser beam (8) passes through a metal film (5) clamped on an upper superposed glass sheet (6) to be welded and a lower superposed glass sheet (4) to be welded, a peak cone light wire 7 generated by ultrafast laser passes through a preset two-dimensional scanning track, a molten pool with nonlinear absorption effect is generated on the scanning track focus interface of the metal film (5), and a compact welding seam is formed after cooling.

2. The method for improving the welding strength of the glass with the assistance of the vacuum magnetron sputtering interface as claimed in claim 1, wherein the method comprises the following steps: the metal-plated film (5) is plated on the lower glass sheet (4) to be welded.

3. The method for improving the welding strength of the glass with the assistance of the vacuum magnetron sputtering interface as claimed in claim 1, wherein the method comprises the following steps: the clearance between the lower glass sheet (4) to be welded and the upper glass sheet (6) to be welded is less than 1 micron.

4. The method for improving the welding strength of the glass with the assistance of the vacuum magnetron sputtering interface as claimed in claim 1, wherein the method comprises the following steps: in order to ensure that two glass sheet samples to be welded do not fall off after welding, the total welding area is more than or equal to 1 square millimeter.

5. The method for improving the welding strength of the glass with the assistance of the vacuum magnetron sputtering interface as claimed in claim 1, wherein the method comprises the following steps: the laser emitted by the ultrashort pulse laser is near infrared light, the wavelength of the laser is 1030nm, the pulse width is 215fs, the repetition frequency is 75kHz-615kHz, and the average power is 1W-10W.

6. The method for improving the welding strength of the glass with the assistance of the vacuum magnetron sputtering interface as claimed in claim 1, wherein the method comprises the following steps: the lower glass sheet (4) to be welded and the upper glass sheet (6) to be welded are two pieces of quartz glass, a nickel film with the thickness of 50nm-100nm is plated on one side of the lower glass sheet and the upper glass sheet by a high vacuum magnetron sputtering system, and the scanning speed is 1000 mu m/s-2000 mu m/s.

7. The method for improving the welding strength of the glass with the assistance of the vacuum magnetron sputtering interface as claimed in claim 1, wherein the method comprises the following steps: the scanning is in a shape of a Chinese character ji, the line spacing is 50-200 μm, and the scanning area is 1 × 1mm²-10×10mm²。