CN117658430A - High-efficiency high-strength ultrafast laser welding method for transparent material - Google Patents

Abstract

The invention provides a high-efficiency ultrafast laser welding method for transparent materials, which specifically comprises the following steps: stacking welding materials and clamping the welding materials by a clamp; regulating ultrafast laser, focusing the laser by a single lens, then interacting with a material, forming plasma on the surface of the front-stage laser focusing material, expanding the plasma outwards in a hemispherical shape, forming an optical interface at the front end, and reflecting the subsequent laser when passing through the optical interface, wherein reflected light interferes with unreflected light, so that a concentric annular light path is formed on the surface of the material; adjusting an ultrafast laser focus to be placed at a specific position, heating and melting materials under the action of concentric annular light spots, and then heating and melting upper materials through heat conduction to realize mutual melting and connection of the two materials, wherein the two materials are in a concentric annular welding structure; and welding by using ultra-fast laser according to the specified path. The invention can use high pulse energy ultrafast laser for welding, has the advantages of high efficiency and simplicity, and can realize high-quality, high-strength and high-efficiency welding of transparent materials.

Description

A high-efficiency, high-intensity and ultra-fast laser welding method for transparent materials

Technical field

The invention relates to the field of ultrafast laser welding applications, and in particular to a high-efficiency and high-intensity laser welding method for transparent materials.

Background technique

Transparent materials such as glass, sapphire, organic polymers and various crystal structures have excellent chemical properties, physical properties and optical properties, as well as good mechanical properties, corrosion resistance and high temperature resistance. These properties make them unparalleled in applications such as aerospace, opto-mechanical systems, sensor technology, microelectronics, microfluidics, biomedicine and many more. In the manufacture of devices and equipment, it often becomes imperative to assemble and protect individual components while retaining the inherent properties of the base material, which inevitably entails the challenge of welding homogeneous or dissimilar materials. For example, the welding of transparent/metallic heterogeneous materials is widely used in aerospace, medicine, optical sensing and other applications. The welding of aluminum and glass is widely used in various occasions, including glass-encapsulated diodes, new energy batteries , the welding of optomechanical modules and windshield assemblies, copper and glass is widely used in the fields of electronic packaging and MEMS manufacturing; the welding of transparent homogeneous materials is also widely used in many fields such as optics, electronics, chemistry, decoration, etc. , including optical device manufacturing lenses, prisms, display structure manufacturing, and chemical laboratory reactors, test tubes and other experimental vessels. Currently, available techniques for joining transparent materials include bonding, anodic bonding, ultrasonic welding and brazing. However, these methods have certain limitations in practical applications considering sealing performance, high temperature stability, welding strength, sample size constraints, and processing efficiency. Therefore, new technological approaches are urgently needed to revolutionize the challenges associated with welding transparent materials in device and equipment development.

Ultrafast laser welding, as a new fusion welding method, connects molten glass and metal together by passing the laser through the glass and focusing it on the interface between the glass and the metal, forming a heat source. Ultra-fast laser welding has the advantages of small thermal effect and high precision, and is very suitable for joining various glasses and metals. In this regard, a published patent (CN116768645 A) has been applied for by pre-treating the transparent ceramic and metal surfaces to be connected, and using a clamp Clamping and fixing, and finally using ultra-fast laser to perform specific scanning paths (concentric circles, parallel lines, etc.) to achieve high reliability, low stress and high precision welding of transparent ceramics and metals; the patent (CN 113292233 A) has been applied for and published in A small amount of liquid is added between the two pieces of glass to reduce the gap. High-speed scanning with pulse energy (10-30 μJ) is used to form a translucent weld at the contact point of the two glasses. Low-speed scanning with lower pulse energy is used to weld the glass to achieve the gap. Larger glass seals are welded. However, in the various existing ultrafast laser welding applications, the laser energy for ultrafast laser glass material welding is mainly concentrated on μJ-level pulse energy, resulting in problems such as limited bonding strength and unclear element mixing area, and in the welding process There is often a large amount of laser pulse energy loss during the process, and the laser pulse energy cannot be used efficiently, which causes a waste of energy during the production and processing process and increases the cost of actual processing; at the same time, in existing welding applications, ultra-fast Laser welding is mostly achieved through point scanning, which makes the processing efficiency low. Moreover, because single point action is used to achieve welding, the pulse energy that can be used is also limited, making it difficult to meet actual production and processing needs.

Therefore, how to efficiently utilize pulse energy and how to enhance the bonding strength of homogeneous or heterogeneous ultrafast laser welding of transparent materials have become new problems and challenges. This invention adjusts the ultrafast laser pulse energy up to the mJ level, so that the ultrafast laser is focused by a single lens and acts on the surface of the material below. The material in the focus area absorbs photon energy and ionizes, forming high-temperature and high-density plasma in an ultra-short time. The plasma expands outward in a hemispherical shape and forms a high-density optical interface at the front end of the plasma expansion. When the subsequent laser passes through the optical interface at the front end of the plasma, a certain degree of reflection occurs, and the reflected light and unreflected light Interference eventually forms a concentric annular light path on the surface of the material. Under the action of the concentric annular light spot, the lower material melts, and then the upper material is heated and melted through heat conduction, thereby achieving efficient mutual fusion and connection of the two materials. And it has a concentric ring welding structure; on the one hand, this method uses higher pulse energy to weld, breaking the previous welding method of using lower energy, and at the same time, a single point directly forms a concentric ring welding structure. Improved welding efficiency; on the other hand, the ultra-fast focused area effectively absorbs the pulse energy and synchronizes the preheating process, melting and cooling processes, strengthens the welding bonding strength, improves the utilization of pulse energy, and reduces the pulse energy loss, ultimately forming a high-strength bond of homogeneous or heterogeneous materials. It achieves high-quality, high-efficiency and high-strength welding of transparent materials under high pulse energy conditions.

Contents of the invention

In response to the above problems, the present invention provides a high-efficiency and high-intensity ultrafast laser welding method for transparent materials. The ultrafast laser is focused on the surface of the material through a single lens and acts on it. The material in the focused area absorbs photon energy and ionizes it. High-temperature and high-density plasma is formed in an ultra-short time and gathers on the surface of the material. The plasma expands outward in a hemispherical shape, forming a high-density optical interface at the front end of the plasma expansion. When the subsequent laser passes through the optical interface at the front end of the plasma, a certain degree of Reflection, the reflected light interferes with the unreflected light, and finally forms a concentric annular light path on the surface of the material. Under the action of the concentric annular light spot, the lower material melts, and then the upper material is heated and melted through thermal conduction, thereby achieving two The efficient mutual melting or combination of two materials and the formation of a concentric annular welding structure improves the strength and quality of transparent materials during welding, improves the utilization efficiency of ultrafast laser energy, simplifies the welding process, and realizes high pulse energy transparent materials Ultra-fast laser welding.

In order to achieve the above objectives, the present invention provides a high-efficiency and high-strength welding method for transparent materials, including the following steps:

(1) By stacking transparent materials and transparent materials or metal materials, with the transparent material on top, and clamping them with clamps;

(2) Adjust the ultrafast laser so that the laser is focused on the material surface through a single lens. After the ultrafast laser is focused in the front stage, it interacts with the material. The material in the focus area absorbs photon energy and ionizes, forming a high-temperature and high-density plasma in an ultra-short time. , and gather on the surface of the material. The plasma expands outward in a hemispherical shape, forming a high-density optical interface at the front end of the plasma expansion. When the subsequent laser passes through the optical interface at the front end of the plasma, a certain degree of reflection occurs, and the reflected light and unreflected light are generated. Interference, thereby forming concentric annular light paths on the surface of the material;

(3) Adjust the focus of the ultrafast laser to a specific position. The plasma optical interface on the surface of the material below causes the ultrafast laser to interfere and form a concentric annular light spot. Under the action of the concentric annular light spot, the material below is heated and Melting, then heating and melting the upper material through heat conduction, thereby achieving efficient mutual fusion and connection of the two materials, and forming a concentric ring-shaped welding structure;

(4) The ultrafast laser welds according to the specified path, and finally achieves sample welding.

Furthermore, the ultrafast laser is a picosecond laser or a femtosecond laser, with a wavelength in the range of 266-2000nm, and its pulse energy can reach up to mJ level.

Further, the optical interface is a plasma shock wave that expands outward in a hemispherical shape at the center of the focus and squeezes the air between the materials, forming a high-density thin film interface between the two materials. This thin film interface expands in a hemispherical shape in the plasma. The outermost layer is the plasma expansion front end.

Furthermore, the concentric annular optical path is formed because after the laser acts on the surface of the material, plasma is generated and expands into a hemispherical shape. At the same time, a high-density optical interface is formed at the front end of the plasma expansion, causing the laser to interfere.

Furthermore, the concentric ring welding structure is a concentric ring-shaped melting achieved by interference of high pulse energy laser beams, and the energy in the interference constructive region is higher than the material melting threshold.

Furthermore, the laser focus is the middle of the sample when welding transparent/metal heterogeneous materials, and is 0 μm-100 μm below the upper surface of the lower sample when welding transparent/transparent homogeneous materials.

Further, the upper material is a transparent brittle material, and the lower material is a transparent brittle material or a metal material.

Furthermore, the transparent material is sapphire, fused quartz, ceramic, silicon and other materials, and the material does not need to be polished.

Furthermore, the metal material is Invar steel, titanium alloy, aluminum alloy, copper and other materials, and the material does not need to be polished.

Furthermore, a high-efficiency, high-intensity ultrafast laser welding method for transparent materials includes a laser, a beam expander, a reflector and a focusing mirror, and is characterized in that it also includes a method for adjusting the optical path of the laser emitted by the laser to be perpendicular to the target. Optical components for processing the surface of the workpiece, a clamp for clamping the stacked samples, and a motion platform for driving the clamp to adjust the gap between the upper material sample and the lower material sample.

Generally speaking, compared with the prior art, the above technical solution of the present invention mainly has the following advantages:

1. In the ultrafast laser welding method of homogeneous or heterogeneous transparent materials, lower laser pulse energy is used for welding. Through the accumulation of heat, the material undergoes melting, sputtering and heat transfer, and finally achieves the welding of the two materials. welding. When a lower pulse energy is focused on the material surface, the effective melting area is only the center of the focus, and there is also energy accumulation in the surrounding areas but it cannot meet the melting requirements of the material, resulting in most of the energy in the focus area not being able to melt. Effectively utilized. The invention adjusts the ultrafast laser to emit pulse energy up to mJ level, so that the ultrafast laser is focused on the surface of the material through a single lens and generates plasma, so that the generated plasma participates in the welding process, and the plasma expands outward in a hemispherical shape. , a high-density optical interface is formed at the front end of the plasma expansion, which causes a certain degree of interference phenomenon to form a concentric annular optical path. The energy in the interference constructive region reaches the melting threshold of the material under high pulse conditions and causes it to melt. Therefore, The material can be welded in a larger area, which effectively solves the problem of ablation of materials caused by high-energy ultrafast laser but cannot be used for welding, and is conducive to the further promotion of high-pulse energy ultrafast laser welding technology and methods.

2. Specifically, the phenomenon of laser interference caused by the plasma optical interface causes the beam to exhibit a periodic energy distribution in the radial direction, forming interference fringes similar to Newton's rings on the material surface, which is further understood as a ring beam, and because The high pulse energy in the interference constructive region causes the material to reach the melting threshold, and the material directly melts, sputters, and welds, achieving a single-point concentric ring welding structure, achieving higher efficiency of single-point welding, and overall improving the welding efficiency. efficiency.

3. In addition, with the support of the above advantages, during each single-point welding of ultrafast laser, due to the annular beam formed, each annular stripe has the same pulse energy and can melt and cool the material at the same time, and the focused area simultaneously Molten sputtering and heat transfer occur under a single ultrafast laser focus, and are cooled and solidified simultaneously after the laser focus is completed. This phenomenon provides a stronger closed ring welding structure for the welding surface, and on the other hand makes the single The concentric ring structures of secondary welding are produced simultaneously, which reduces the shear strength of the welding interface and solves the problem that the welding process can only occur gradually but not simultaneously during scanning welding, which can further improve the welding stability and improve the welding air tightness.

Description of drawings

Figure 1 is a system diagram of high-intensity laser welding equipment for transparent materials and transparent materials or metal materials according to the present invention.

Figure 2 is a schematic diagram of the concentric ring structure on the surface of the lower material 9 in the welding equipment system of the present invention.

Figure 3 is a schematic diagram of a concentric ring structure formed by high pulse energy ultrafast laser action on ceramic materials in an embodiment of the present invention.

Explanation of reference signs: 1-ultrafast laser; 2-control system; 3-laser beam; 4-beam expander; 5-beam expander laser beam; 6-reflector; 7-focusing mirror; 8-upper material; 9 -Material below; 10-Concentric ring welding structure; 11-Laser welding focus.

Detailed ways

In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, a detailed description will be given below with reference to the accompanying drawings and specific embodiments. It should be noted here that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

The present invention provides a high-efficiency and high-strength welding method for transparent materials in order to solve the problems that existing welding solutions are difficult to use high pulse energy laser for welding, it is difficult to fully utilize the laser pulse energy for welding, and it is difficult to form a high-strength welding surface.

The structure of an example provided by the present invention is shown in Figure 1. It is a device for ultrafast laser welding of high pulse energy transparent materials. The equipment consists of ultrafast laser 1, control system 2, beam expander 4, reflector 6, focusing mirror 7 and workbench.

In this embodiment, the ultrafast laser 1, the beam expander 4, the reflecting mirror 6 and the focusing mirror 7 are located on the same optical path, and the optical path enters the focusing mirror 7 vertically after being reflected by the reflecting mirror 6. The condenser 7 is located above the workbench. The control system 2 is connected to the ultrafast laser 1 and the workbench respectively, and is used to control their operation.

Ultrafast lasers usually emit picosecond lasers or femtosecond lasers, and the wavelength range of the output beam of ultrafast lasers is 266-2000nm.

When working, the ultrafast laser 1 outputs a wavelength range (266-2000nm), and the output pulse energy can be up to mJ-level femtosecond laser. The laser beam 3 is expanded by the beam expander 4 and then expanded by the reflector 6. The laser beam 5 is reflected; the expanded laser beam 5 is focused to a specific position through the focusing mirror 7. The specific position for welding transparent/metallic heterogeneous materials is the middle of the sample, and the specific position for welding transparent/transparent homogeneous materials is on the lower sample. 0μm-100μm below the surface. The control system 2 controls the ultrafast laser 1 and the workbench to perform welding at a specific position. The ultrafast laser is focused to the surface of the material through the focusing mirror 7. The ultrafast laser interacts with the material 9 below. The front-end laser causes the surface of the material 9 below to gather and form plasma. The plasma expands outward in a hemispherical shape. When the plasma expands, A high-density optical interface is formed at the front end. When the subsequent laser passes through the optical interface, a certain degree of reflection occurs. The reflected light interferes with the unreflected light, and finally a concentric annular light path is formed on the surface of the material. The material melts under the action of the concentric annular light spot. , and then heats and melts the upper material through heat conduction, thereby achieving efficient mutual fusion and connection of the two materials, and forming a concentric ring-shaped welding structure 10 to complete the homogeneous or heterogeneous welding of high pulse energy transparent materials.

Specific examples:

Example 1: In this example, the upper material 8 is quartz glass and the lower material 9 is alumina ceramic (purity 96%). The size of the fused quartz glass is selected to be approximately 30mm×30mm×3mm, and the size of the alumina ceramic is approximately 30mm × 30mm × 3mm, the surface of the experimental preservation sample is clean, and there is no need to do any treatment on the sample surface. Laser welding is performed according to the steps in the method of high-efficiency, high-intensity and ultra-fast laser welding of transparent materials provided in the above embodiments.

In the step of welding transparent materials and ceramic materials, the control system 2 allows the high-energy laser 3 emitted by the ultrafast laser 1 to pass through the upper quartz glass 8 and then focus on a specific position, and the specific position is the middle of the sample. The output wavelength of the ultrafast laser is set to 800nm, the repetition frequency is 1kHz, and the pulse width is 35fs. The control system controls the laser and the workbench to weld according to the set welding route. The high-energy laser beam with a pulse energy of 100μJ passes through the focusing lens. 7, an interference phenomenon occurs at the front-end optical interface of the plasma on the surface of the alumina ceramic 9, producing a radially periodic ring-shaped beam. The energy in the interference constructive region is higher than the melting threshold of the alumina ceramic and causes it to melt. The alumina below The ceramic 9 is melted and sputtered, and the upper quartz glass 8 is heated and melted through thermal conduction, thereby achieving efficient mutual fusion and connection of the transparent material and the ceramic material, and forming a concentric ring-shaped welding structure, thereby completing the welding between the transparent/ceramic materials .

Example 2: In this example, the upper material 8 is quartz glass and the lower material 9 is quartz glass. The dimensions of the quartz glass are selected to be 10mm × 10mm × 6mm. The impurity content of the sample is 5ppm. The four sides of the quartz glass are polished. According to the above The embodiment provides a method for performing high-efficiency, high-intensity, ultra-fast laser welding of transparent materials by performing laser welding.

In the step of welding transparent materials to transparent materials, the high-energy laser 3 emitted by the ultrafast laser 1 passes through the upper quartz glass 8 through the control system 2 and is focused on a specific position. The specific position is 15 μm below the upper surface of the quartz glass 9 . The output wavelength of the ultrafast laser is set to 800nm, the repetition frequency is 1kHz, and the pulse width is 35fs. The control system controls the laser and the workbench to weld according to the set welding route. The high-energy laser beam with a pulse energy of 2mJ passes through the focusing lens. 7, an interference phenomenon occurs at the front end optical interface of the plasma on the surface of the quartz glass 9, producing a ring-shaped beam with a periodic distribution in the radial direction. The energy in the interference constructive region is higher than the melting threshold of the quartz glass and causes it to melt, and the quartz glass 9 below melts. The upper quartz glass 8 is heated and melted by sputtering and heat conduction, thereby achieving efficient mutual fusion and connection of the two transparent materials, and forming a concentric ring-shaped welding structure, thereby completing the welding between transparent/transparent materials.

Claims (10)

1. A high-efficiency and high-strength ultrafast laser welding method for transparent materials is characterized by comprising the following steps:

step one, stacking a transparent material and a transparent material or a metal material, wherein the transparent material is arranged above the transparent material and clamped by a clamp;

step two, regulating ultrafast laser, enabling the laser to be focused on the surface of a material through a single lens, enabling the front-stage ultrafast laser to interact with the material after being focused, enabling the material in a focus area to absorb photon energy and ionize, forming high-temperature high-density plasmas in an ultrashort time, gathering the plasmas on the surface of the material, enabling the plasmas to be expanded outwards in a hemispherical shape, forming a high-density optical interface at the front end of the plasma expansion, enabling the subsequent laser to be reflected to a certain extent when passing through the front-end optical interface of the plasma, enabling reflected light to interfere with unreflected light, and forming a concentric annular light path on the surface of the material;

step three, adjusting an ultrafast laser focus to be placed at a specific position, wherein a plasma optical interface on the surface of a lower material causes interference phenomenon of ultrafast laser and forms concentric annular light spots, the lower material is heated and melted under the action of the concentric annular light spots, and then the upper material is heated and melted through heat conduction, so that the two materials are efficiently fused and connected with each other, and the coaxial annular welding structure is formed;

and fourthly, welding by using ultra-fast laser according to a specified path, and finally realizing sample welding.

2. The method for high-efficiency, high-intensity ultrafast laser welding of transparent materials as recited in claim 1, wherein in the second step, the ultrafast laser is picosecond laser or femtosecond laser, the wavelength is in the range of 266-2000nm, and the pulse energy can reach mJ level at the highest.

3. The method of claim 1, wherein in the second step, the optical interface is a plasma shock wave expanding outwards in a hemispherical shape with a focus center and extruding air between materials, so that a high-density thin film interface is formed between the two materials, and the thin film interface is the plasma expansion front end at the outermost layer of the hemispherical expansion of the plasma.

4. The method for high-efficiency, high-strength and ultra-fast laser welding of transparent materials according to claim 1, wherein in the second step, the concentric circular ring-shaped optical path is formed by generating plasma and expanding into a hemispherical shape after the laser acts on the surface of the material, and simultaneously forming a high-density optical interface at the front end of the plasma expansion, so that the laser generates interference phenomenon.

5. The method for high-efficiency, high-strength and ultra-fast laser welding of transparent materials according to claim 1, wherein in the third step, the concentric ring welding structure is concentric ring melting realized by the energy of the interference constructive area being higher than the melting threshold of the materials after the interference of the high-pulse energy laser beams.

6. The method of high-efficiency, high-strength ultrafast laser welding of transparent materials, as recited in claim 1, wherein in step three, the laser focus is between 0 μm and 100 μm below the upper surface of the sample below when welding transparent/metallic heterogeneous materials.

7. The method of claim 1, wherein in step three, the upper material is a transparent brittle material and the lower material is a transparent brittle material or a metal material.

8. The method of high efficiency, high strength, ultra-fast laser welding of transparent materials according to claim 1, wherein the transparent materials are sapphire, fused silica, ceramic, silicon, etc., which may not be polished.

9. The method of claim 1, wherein the metal material is invar, titanium alloy, aluminum alloy, copper, or the like, and the material is not polished.

10. The high-efficiency high-strength ultrafast laser welding method for transparent materials comprises a laser, a beam expander, a reflecting mirror, a focusing mirror, an optical assembly, a clamp and a moving platform, wherein the optical assembly is used for adjusting the light path of laser emitted by the laser to be perpendicular to the surface of a workpiece to be processed, the clamp is used for clamping stacked samples, the moving platform drives the clamp to move, and the clamp can adjust a gap between an upper material sample and a lower material sample.