Laser processing method and system for through holes in transparent brittle materials

Abstract

This application discloses a laser processing method and system for creating through-holes in transparent brittle materials, belonging to the field of laser processing. The laser processing method for creating through-holes in transparent brittle materials includes the following steps: sequentially generating a first Bessel beam and a second Bessel beam, which are coaxially focused on the transparent brittle material; processing according to preset parameters, whereby the first Bessel beam forms a through-hole inside the transparent brittle material, and the second Bessel beam modifies the inner wall of the through-hole along the through-hole; removing debris from the hole to obtain a finished transparent brittle material product including the through-hole; wherein the emission time difference between the first and second Bessel beams is 10 microseconds to 100 microseconds, and the difference in focal depth between the first and second Bessel beams is ≤0.5 mm. The laser processing method for creating through-holes in transparent brittle materials of this application achieves high micro-hole precision and a high yield.

Description

Technical Field

[0001] This application relates to the field of laser processing, and in particular to a laser processing method and system for through holes in transparent brittle materials. Background Technology

[0002] In high-end application fields such as optical devices, semiconductor packaging, microfluidic chips and optical communications, the demand for micropore processing of transparent and brittle materials is growing, and increasingly stringent requirements are being placed on the aspect ratio, wall quality, dimensional accuracy and processing efficiency of the micropores.

[0003] Existing laser processing methods mainly use a single laser beam to perforate transparent and brittle materials. However, because the energy deposition mode of a single laser beam inside the material is singular, material removal and hole wall formation occur simultaneously during the processing. The laser impact and thermal effects are concentrated on the hole wall surface, which can easily lead to defects such as microcracks, molten residue adhesion, and edge chipping. These defects severely affect the smoothness and structural integrity of the hole wall, reducing the quality and yield of the microholes. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application provides a laser processing method for through holes in transparent and brittle materials, aiming to solve the problems of roughness and poor quality and yield of microholes caused by current laser processing of through holes in transparent and brittle materials.

[0005] To achieve the above objectives, this application proposes a laser processing method for through-holes in transparent brittle materials, comprising the following steps: sequentially generating a first Bessel beam and a second Bessel beam, the first Bessel beam and the second Bessel beam being coaxially focused on the transparent brittle material; processing according to preset parameters, the first Bessel beam forming a through-hole inside the transparent brittle material, the second Bessel beam modifying the inner wall of the through-hole along the through-hole; removing debris from the hole to obtain a finished transparent brittle material product including the through-hole; wherein, the emission time difference between the first Bessel beam and the second Bessel beam is 10 microseconds to 100 microseconds, and the difference in focal depth length between the first Bessel beam and the second Bessel beam is ≤0.5 mm.

[0006] In some embodiments, the wavelengths of the first Bessel beam and the second Bessel beam are each selected from the range of 355nm to 1550nm, and the difference between the wavelengths of the first Bessel beam and the second Bessel beam is 20nm to 80nm.

[0007] In some embodiments, the wavelength of the first Bessel beam is 1000nm~1080nm, and the wavelength of the second Bessel beam is 1040nm~1100nm.

[0008] In some embodiments, the single-pulse energy of the first Bessel beam is 100 μJ to 600 μJ; and / or, the single-pulse energy of the second Bessel beam is 1 mJ to 20 mJ.

[0009] In some embodiments, the pulse width of the second Bessel beam is at least 10 times the pulse width of the first Bessel beam. 6 times.

[0010] In some embodiments, the pulse width of the first Bessel beam is 700 fs to 15 ps, and the pulse width of the second Bessel beam is 10 μs to 100 μs.

[0011] In some embodiments, the preset parameters include a processing speed of 40 μm / s to 80 μm / s.

[0012] In some embodiments, the thickness of the transparent brittle material is 1 mm to 20 mm; and / or, the transparent brittle material includes at least one of glass, gemstone crystal, and transparent ceramic.

[0013] In some embodiments, removing debris from the orifice includes purging with an inert gas at a pressure of 0.1 MPa to 0.3 MPa.

[0014] To achieve the above objectives, this application also proposes a laser processing system for through-holes in transparent and brittle materials. The system is used to perform the aforementioned laser processing method for through-holes in transparent and brittle materials. The system includes: a laser emitting module for emitting a first laser beam and a second laser beam; a conical lens module for shaping the laser beams into a first Bessel beam and a second Bessel beam; a lens module disposed on the output optical path of the conical lens module for adjusting the focusing depth of the Bessel beam; a beam combiner module disposed at the intersection of the output optical paths of the first and second Bessel beams for combining the first and second Bessel beams into a coaxial beam; and a focusing objective lens disposed on the output optical path of the beam combiner for focusing the coaxial beam onto the transparent and brittle material.

[0015] In this application, the first Bessel beam forms a region of uniform energy deposition along the optical axis inside the transparent brittle material, completing the through-hole forming that penetrates the thickness of the material in one process. After the through-hole is initially formed, the second Bessel beam performs secondary modification on the hole wall along the same optical axis path. Throughout the entire process, the two Bessel beams do not require the introduction of chemical auxiliary means. The complete processing chain from forming to modification can be completed simply by matching the timing of the beam parameters and the spatial overlap. Finally, residual debris is removed by purging to obtain a high-quality transparent brittle material product including the through-hole. Detailed Implementation

[0016] To make the technical solutions and advantages of this application clearer, the application and its beneficial effects will be described in further detail below in conjunction with specific embodiments. The following description is provided to enable those skilled in the art to fully understand this application and is not intended to limit the subject matter recorded in the claims.

[0017] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0018] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0019] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0020] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0021] Existing laser processing methods mainly use a single laser beam to perforate transparent and brittle materials. However, because the energy deposition mode of a single laser beam inside the material is singular, material removal and hole wall formation occur simultaneously during the processing. The laser impact and thermal effects are concentrated on the hole wall surface, which can easily lead to defects such as microcracks, molten residue adhesion, and edge chipping. These defects severely affect the smoothness and structural integrity of the hole wall, reducing the quality and yield of the microholes.

[0022] In view of this, this application proposes a laser processing method for through holes in transparent brittle materials, comprising the following steps: S1: A first Bessel beam and a second Bessel beam are generated sequentially, and the first Bessel beam and the second Bessel beam are coaxially focused on a transparent and brittle material; S2: Processing is performed according to preset parameters. The first Bessel beam forms a through hole inside the transparent brittle material, and the second Bessel beam modifies the inner wall of the through hole along the through hole. S3: Remove debris from the hole to obtain a transparent brittle material product including a through hole; wherein the light emission time of the first Bessel beam and the second Bessel beam differs by 10 microseconds to 100 microseconds, and the difference in focal depth length between the first Bessel beam and the second Bessel beam is ≤0.5 mm.

[0023] By utilizing two coaxially focused Bessel beams, which are assigned to two different processing stages—"shaping" and "refining"—within a preset time sequence, the timing of material removal and hole wall quality optimization is separated. Specifically, the first Bessel beam forms a region of uniform energy deposition along the optical axis inside the transparent and brittle material, completing the through-hole forming that penetrates the material thickness in a single process. After the initial through-hole forming, the second Bessel beam performs secondary refinement of the hole wall along the same optical axis path.

[0024] To ensure that the second beam of light precisely covers the entire inner wall area of ​​the through-hole formed by the first beam, this application limits the difference in focal depth length between the two beams to no more than 0.5 mm. The effective area of ​​the second beam coincides spatially with the inner wall of the through-hole formed by the first beam, avoiding unmodified or unevenly modified areas of the hole wall due to excessive difference in focal depth. Simultaneously, the time difference between the two beams is controlled within 10 to 100 microseconds. This timing constraint ensures that the second beam intervenes promptly after the first beam completes its application, before significant cooling and shrinkage or debris deposition occurs on the hole wall, resulting in a precise modification effect. Furthermore, within this time difference range, the processed areas of the two beams remain in similar thermodynamic states, preventing the material properties from reverting due to excessive time intervals and increasing the difficulty of secondary processing.

[0025] Throughout the entire processing, the two Bessel beams require no chemical assistance; the complete processing chain from shaping to finishing is achieved solely through timing matching and spatial overlap of beam parameters. Finally, residual debris is removed by purging, resulting in a high-quality through-hole. Through this synergistic mechanism, this method effectively avoids the stress concentration and thermal damage problems caused by simultaneous material removal and hole wall shaping in single-beam laser processing. It significantly improves the hole wall quality and processing yield of through holes without adding processing steps.

[0026] For example, the difference in light emission time between the first Bessel beam and the second Bessel beam is 10μs, 20μs, 30μs, 40μs, 50μs, 60μs, 70μs, 80μs, 90μs, or 100μs, or falls within any two of the above values.

[0027] For example, the difference in focal depth between the first Bessel beam and the second Bessel beam is 0 mm, 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, or 0.5 mm, or falls within the range of any two of the above values.

[0028] In some embodiments, the wavelengths of the first Bessel beam and the second Bessel beam are each selected from the range of 355nm to 1550nm, and the difference between the wavelengths of the first Bessel beam and the second Bessel beam is 20nm to 80nm.

[0029] This scheme covers the ultraviolet to near-infrared wavelength range, enabling both beams of light to transmit effectively in transparent and brittle materials, with sufficient penetration depth to form stable energy deposition inside the material.

[0030] The wavelength difference between the two beams is 20nm~80nm. The first Bessel beam excites electrons along the optical filament channel inside the transparent brittle material, changing the optical absorption characteristics of the local material and causing a red shift in the absorption band edge of the modified region. The wavelength of the second Bessel beam is set to be 20nm~80nm longer than that of the first beam, so that the longer wavelength light is selectively absorbed only by the modified region. This is beneficial for the second beam to be effectively absorbed by the modified channel to achieve uniform heating and vaporization.

[0031] For example, the wavelength difference between the first Bessel beam and the second Bessel beam is 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, or 80nm, and each wavelength is within the range of 355nm to 1550nm, or within the range formed by any two of the above differences.

[0032] In some embodiments, the wavelength of the first Bessel beam is 1000nm~1080nm; and / or, the wavelength of the second Bessel beam is 1040nm~1100nm.

[0033] The wavelengths 1000nm–1080nm and 1040nm–1100nm both fall within the near-infrared band. This band lies within the light transmission window of transparent and brittle materials, where absorption is low. This allows the beam to penetrate the material surface and deposit energy with a long focal depth without significant attenuation. These wavelength ranges cover the main output bands of ytterbium-doped fiber lasers and solid-state lasers. The related laser technologies are mature and widely used in industry, which is conducive to the industrialization and implementation of this method.

[0034] For example, the wavelength of the first Bessel beam is 1000nm, 1010nm, 1020nm, 1030nm, 1040nm, 1050nm, 1060nm, 1070nm, or 1080nm, or falls within the range of any two of the above values.

[0035] For example, the wavelength of the second Bessel beam is 1040nm, 1050nm, 1060nm, 1070nm, 1080nm, 1090nm, or 1100nm, or falls within the range of any two of the above values.

[0036] In some embodiments, the single-pulse energy of the first Bessel beam is 100 μJ to 600 μJ; and / or, the single-pulse energy of the second Bessel beam is 1 mJ to 20 mJ.

[0037] The energy of the first Bessel beam is set at a relatively low microjoule level, its purpose being to modify the transparent and brittle material. Within this energy range, when short pulses on the order of picoseconds interact with the material, the peak power density is sufficient to excite free electrons within the material through multiphoton absorption and tunneling ionization, forming a continuous modification channel along the beam propagation direction.

[0038] The second Bessel beam, with its energy set at a high millijoule level, serves to uniformly heat and vaporize the modified material within the channel. Since the first beam has significantly increased the optical absorption coefficient of the modified region, the second beam, selectively absorbed by this region, rapidly deposits millijoule-level energy along the entire channel, heating the modified material and achieving vaporization removal. The selection of this energy range requires balancing two factors: firstly, the energy must be high enough to drive sufficient vaporization of the material within the channel, avoiding residue or blockage; secondly, the energy must be controlled within a reasonable upper limit to prevent excess energy from diffusing heat to the unmodified transparent brittle material, thus avoiding thermal stress damage or microcracks.

[0039] For example, the single-pulse energy of the first Bessel beam is 100μJ, 150μJ, 200μJ, 250μJ, 300μJ, 350μJ, 400μJ, 450μJ, 500μJ, 550μJ, or 600μJ, or falls within the range of any two of the above values.

[0040] For example, the single-pulse energy of the second Bessel beam is 1mJ, 2mJ, 3mJ, 4mJ, 5mJ, 6mJ, 7mJ, 8mJ, 9mJ, 10mJ, 11mJ, 12mJ, 13mJ, 14mJ, 15mJ, 16mJ, 17mJ, 18mJ, 19mJ, or 20mJ, or falls within the range of any two of the above values.

[0041] In some embodiments, the pulse width of the second Bessel beam is at least 10 times the pulse width of the first Bessel beam. 6 times.

[0042] Two laser beams span at least six orders of magnitude across the timescale. The first beam acts on the material with an ultrashort pulse, forming a continuous modification channel through nonlinear ionization with almost no thermal damage. Subsequently, the second beam acts on the same region with a long pulse. Due to the sufficiently long pulse width, the efficiency of converting light energy into heat energy is significantly improved, enabling uniform heating and vaporization removal along the modification channel.

[0043] In some embodiments, the pulse width of the first Bessel beam is 700 fs to 15 ps, and the pulse width of the second Bessel beam is 10 μs to 100 μs.

[0044] The first Bessel beam (700 fs to 15 ps) is an ultrashort pulse. This pulse width range is much shorter than the relaxation time of electron-phonon coupling in transparent and brittle materials (typically on the order of picoseconds to nanoseconds). When laser energy is deposited inside the material, heat does not have time to diffuse to the lattice, and energy absorption is dominated by nonlinear processes such as multiphoton ionization and tunneling ionization. The lower limit of 700 fs ensures that the peak power density is sufficient to overcome the ionization threshold of transparent materials and achieve stable free electron excitation; the upper limit of 15 ps ensures that the thermal diffusion effect is negligible throughout the pulse width range, and no heat accumulation or thermal stress damage occurs in the modified region.

[0045] The second Bessel beam (10μs–100μs) is a long pulse. This pulse width range is much longer than the thermal diffusion time of the material. The laser energy is fully converted into lattice thermal energy through electron-phonon coupling, achieving material heating primarily through thermal effects. Since the first beam has significantly improved the optical absorption coefficient of the modified channel, the second beam is selectively absorbed in this region. The microsecond-level pulse width ensures that heat accumulates uniformly along the entire channel, allowing the modified material to be fully heated above its vaporization temperature and completely removed. The lower limit of 10μs allows the thermal conversion process to proceed fully, ensuring complete vaporization of the material without residue due to insufficient heating time; the upper limit of 100μs confines the heating range within the modified channel, preventing heat from being conducted to the unmodified parent material region via thermal diffusion.

[0046] For example, the pulse width of the first Bessel beam is 700 fs, 1 ps, 2 ps, 3 ps, 4 ps, 5 ps, 6 ps, 7 ps, 8 ps, 9 ps, 10 ps, ​​11 ps, 12 ps, 13 ps, 14 ps, or 15 ps, or falls within the range of any two of the above values.

[0047] For example, the pulse width of the second Bessel beam is 10μs, 20μs, 30μs, 40μs, 50μs, 60μs, 70μs, 80μs, 90μs, 100μs, or within any two of the above values.

[0048] In some embodiments, the preset parameters include a processing speed of 40 μm / s to 80 μm / s.

[0049] Within this speed range, the two Bessel beams can achieve precise spatial overlap within the transparent, brittle material. The first picosecond beam scans along a predetermined path, forming a continuous modification channel within the material; the second microsecond beam then scans along the same path. By controlling the time difference between the two beams (10μs to 100μs) to match the processing speed, it is beneficial to avoid excessively slow processing speeds, resulting in excessively high energy density deposited per unit area, causing thermal stress damage, and excessively large scanning spacing or insufficient overlap, which could lead to some areas not being fully heated by the second beam, incomplete material vaporization, and residues within the channels.

[0050] For example, the processing speed is 40μm / s, 45μm / s, 50μm / s, 55μm / s, 60μm / s, 65μm / s, 70μm / s, 75μm / s, 80μm / s, or within the range of any two of the above values.

[0051] In some embodiments, the thickness of the transparent brittle material is 1 mm to 20 mm; the transparent brittle material includes at least one of glass, gemstone crystal, and transparent ceramic.

[0052] At this thickness, single-beam laser processing faces two challenges: Gaussian beams lack sufficient depth of focus to penetrate in a single pass, while Bessel beams, despite their long depth of focus, suffer from severe energy attenuation along the path in thick materials, only achieving modification rather than complete removal. This solution addresses these challenges by employing a dual-beam, time-sequential synergy approach. The first picosecond beam forms a continuous modification channel along the entire thickness, while the second microsecond beam utilizes the absorption enhancement effect in the modified region to uniformly heat and remove material along the entire channel. This method allows for single-pass processing within this thickness range, eliminating the need for layer-by-layer scanning or multiple positioning steps.

[0053] In some embodiments, the aspect ratio of the through-holes in the transparent brittle material of this thickness can reach 50:1 or more.

[0054] In some embodiments, the glass material includes, for example, quartz glass, borosilicate glass, aluminosilicate glass, soda-lime-silica glass, fused silica, alkali-free glass, tempered glass, and microcrystalline glass; the crystalline material includes, for example, sapphire, diamond, lithium niobate, lithium tantalate, and titanium sapphire; and the transparent ceramic material includes, for example, alumina ceramics, aluminum oxynitride transparent ceramics, zirconium oxide ceramics, and magnesium aluminum spinel transparent ceramics.

[0055] For example, the thickness of the transparent brittle material is 1 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, or 20 mm, or falls within the range of any two of the above values.

[0056] In some embodiments, removing debris from the orifice includes purging with an inert gas at a pressure of 0.1 MPa to 0.3 MPa.

[0057] This pressure range can generate an airflow with sufficient momentum to drive the tiny debris remaining inside the pore out along the axial direction of the through-hole, and the airflow velocity is sufficient to overcome the surface adhesion between the debris and the pore wall and the gravity settling of the debris itself. For micropores with a diameter of only tens of micrometers and a depth of several millimeters, the internal space of the pore is extremely narrow, and the resistance to the movement of debris inside the pore is large. A pressure of 0.1MPa to 0.3MPa can form a stable laminar or weakly turbulent flow state, allowing the debris to be smoothly discharged out of the pore along the direction of the through-hole with the airflow.

[0058] For example, the purging pressure is 0.10 MPa, 0.15 MPa, 0.20 MPa, 0.25 MPa, 0.30 MPa, or within the range of any two of the above values.

[0059] To address the aforementioned problems, this application also proposes a laser processing system for through-holes in transparent and brittle materials. The system is used to perform the aforementioned laser processing method for through-holes in transparent and brittle materials, and the system includes: A laser emitting module, used to emit a first laser beam and a second laser beam; A conical lens module is used to shape the laser beam into a first Bessel beam and a second Bessel beam; A lens module is disposed in the output light path of the conical lens module and is used to adjust the focusing depth of the Bessel beam; A beam combiner module is located at the intersection of the outgoing optical paths of the first Bessel beam and the second Bessel beam, and is used to combine the first Bessel beam and the second Bessel beam into a coaxial beam. A focusing objective lens is disposed in the output optical path of the beam combiner and is used to focus the coaxial beam onto a transparent and brittle material.

[0060] The laser emitting module outputs a first laser beam and a second laser beam, which enter the conical lens module independently. The first laser beam is shaped into a first Bessel beam by the first conical lens (AX1), and the second laser beam is shaped into a second Bessel beam by the second conical lens (AX2). The two Bessel beams are combined into a coaxial beam at the beam combiner module (BS), and then focused into the interior of the transparent and brittle material by the focusing objective lens.

[0061] In the above system, lens modules (L2, L3) are positioned on the output light path of the second conical lens to adjust the focusing depth of the second Bessel beam. Since the two beams need to achieve focal length matching (difference in focal length ≤ 0.5 mm) within the material along the same processing axis, the focusing depth of the second beam, after being shaped by the second conical lens, is finely adjusted by the lens modules to ensure that its energy distribution range within the material precisely coincides spatially with the modified channel formed by the first beam.

[0062] The system, in conjunction with an inert gas purging device, simultaneously purges debris from the bore during processing, forming a complete processing function chain. The coordinated operation of these modules eliminates the need to transfer workpieces or reposition them between different devices, improving processing efficiency, positioning accuracy, and product consistency.

[0063] The technical solution of this application will be further described in detail below with reference to specific embodiments.

[0064] Example 1 A 1mm thick borosilicate glass was used to sequentially generate a first Bessel beam and a second Bessel beam, both coaxially focused within the borosilicate glass. The first Bessel beam had a wavelength of 1064nm, a pulse width of 700fs, and a single-pulse energy of 500μJ; the second Bessel beam had a wavelength of 1070nm, a pulse width of 50ns, and a single-pulse energy of 5000μJ. The timing difference between the two beams was 20μs, and the difference in focal depth between the two beams was 0.1mm. The preset processing speed was 50μm / s, and the process was purged with argon gas at a pressure of 0.2MPa to obtain a micro-via with a diameter of 20μm.

[0065] Example 2 A 1mm thick synthetic quartz glass is provided. A first Bessel beam and a second Bessel beam are sequentially generated, and the two beams are coaxially focused inside the quartz glass. The first Bessel beam has a wavelength of 1030nm, a pulse width of 5ps, and a single-pulse energy of 250μJ; the second Bessel beam has a wavelength of 1070nm, a pulse width of 30μs, and a single-pulse energy of 12mJ. The timing difference between the two beams is 10μs, and the difference in focal depth between the two beams is 0.5mm. The preset processing speed is 80μm / s, and the process is purged with argon gas at a pressure of 0.18MPa to obtain a micro-via with a diameter of 15μm.

[0066] Example 3 A 1.5mm thick monocrystalline sapphire crystal was used to generate a first Bessel beam and a second Bessel beam, which were coaxially focused within the sapphire crystal. The first Bessel beam had a wavelength of 1030nm, a pulse width of 8ps, and a single-pulse energy of 280μJ; the second Bessel beam had a wavelength of 1070nm, a pulse width of 50μs, and a single-pulse energy of 16mJ. The timing difference between the two beams was 50μs, and the difference in focal depth between the two beams was 0.6mm. The preset processing speed was 40μm / s, and the process was purged with argon gas at a pressure of 0.22MPa to obtain a micro-via with a diameter of 25μm.

[0067] Example 4 A 1mm thick borosilicate glass was used to sequentially generate a first Bessel beam and a second Bessel beam, both coaxially focused within the borosilicate glass. The first Bessel beam had a wavelength of 1064nm, a pulse width of 700fs, and a single-pulse energy of 500μJ; the second Bessel beam had a wavelength of 1070nm, a pulse width of 50ns, and a single-pulse energy of 5000μJ. The timing difference between the two beams was 10μs, and the difference in focal depth between the two beams was 0.5mm. The preset processing speed was 50μm / s, and the process was purged with argon gas at a pressure of 0.2MPa to obtain a micro-via with a diameter of 20μm.

[0068] Example 5 A 1mm thick synthetic quartz glass is provided. A first Bessel beam and a second Bessel beam are generated sequentially, and the two beams are coaxially focused inside the quartz glass. The first Bessel beam has a wavelength of 1030nm, a pulse width of 5ps, and a single pulse energy of 250μJ; the second Bessel beam has a wavelength of 1070nm, a pulse width of 30μs, and a single pulse energy of 12mJ. The timing difference between the two beams is 100μs, and the difference in focal depth between the two beams is 0.3mm. The preset processing speed is 80μm / s, and the process is purged with argon gas at a pressure of 0.18MPa to obtain a micro-hole with a diameter of 15μm.

[0069] Example 6 A 1.5mm thick single-crystal sapphire crystal was used to generate a first Bessel beam and a second Bessel beam, which were coaxially focused within the sapphire crystal. The first Bessel beam had a wavelength of 1030nm, a pulse width of 700fs, and a single-pulse energy of 100μJ; the second Bessel beam had a wavelength of 1050nm, a pulse width of 10μs, and a single-pulse energy of 1mJ. The timing difference between the two beams was 30μs, and the difference in focal depth between the two beams was 0.2mm. The preset processing speed was 60μm / s, and the process was purged with argon gas at a pressure of 0.1MPa to obtain a micro-via with a diameter of 25μm.

[0070] Example 7 A 1mm thick borosilicate glass was used to sequentially generate a first Bessel beam and a second Bessel beam, both coaxially focused within the borosilicate glass. The first Bessel beam had a wavelength of 1000nm, a pulse width of 15ps, and a single-pulse energy of 600μJ; the second Bessel beam had a wavelength of 1080nm, a pulse width of 100μs, and a single-pulse energy of 20mJ. The timing difference between the two beams was 60μs, and the difference in focal depth between the two beams was 0.15mm. The preset processing speed was 40μm / s, and the process was purged with argon gas at a pressure of 0.3MPa to obtain a micro-via with a diameter of 20μm.

[0071] Example 8 A 5mm thick synthetic quartz glass is provided. A first Bessel beam and a second Bessel beam are sequentially generated, and the two beams are coaxially focused inside the quartz glass. The first Bessel beam has a wavelength of 1030nm, a pulse width of 5ps, and a single-pulse energy of 400μJ; the second Bessel beam has a wavelength of 1070nm, a pulse width of 50μs, and a single-pulse energy of 15mJ. The timing difference between the two beams is 40μs, and the difference in focal depth between the two beams is 0.25mm. The preset processing speed is 50μm / s, and the process is purged with argon gas at a pressure of 0.2MPa to obtain a micro-via with a diameter of 40μm.

[0072] Example 9 A 20mm thick monocrystalline sapphire crystal was used to generate a first Bessel beam and a second Bessel beam, which were coaxially focused within the sapphire crystal. The first Bessel beam had a wavelength of 1030nm, a pulse width of 8ps, and a single-pulse energy of 550μJ; the second Bessel beam had a wavelength of 1070nm, a pulse width of 80μs, and a single-pulse energy of 18mJ. The timing difference between the two beams was 70μs, and the difference in focal depth between the two beams was 0.35mm. The preset processing speed was 60μm / s, and the process was purged with argon gas at a pressure of 0.25MPa to obtain a micro-via with a diameter of 80μm.

[0073] Example 10 A 1.2 mm thick transparent alumina ceramic was used to sequentially generate a first Bessel beam and a second Bessel beam, both coaxially focused within the transparent ceramic. The first Bessel beam had a wavelength of 1050 nm, a pulse width of 800 fs, and a single-pulse energy of 350 μJ; the second Bessel beam had a wavelength of 1100 nm, a pulse width of 40 μs, and a single-pulse energy of 8 mJ. The timing difference between the two beams was 25 μs, and the difference in focal depth between the two beams was 0.1 mm. The preset processing speed was 70 μm / s, and the process was purged with argon gas at a pressure of 0.15 MPa to obtain a micro-hole with a diameter of 30 μm.

[0074] Example 11 A 2mm thick borosilicate glass was used to sequentially generate a first Bessel beam and a second Bessel beam, both coaxially focused within the borosilicate glass. The first Bessel beam had a wavelength of 1040nm, a pulse width of 1ps, and a single-pulse energy of 450μJ; the second Bessel beam had a wavelength of 1090nm, a pulse width of 60μs, and a single-pulse energy of 10mJ. The timing difference between the two beams was 80μs, and the difference in focal depth between the two beams was 0.05mm. The preset processing speed was 55μm / s, and the process was purged with argon gas at a pressure of 0.2MPa to obtain a micro-via with a diameter of 25μm.

[0075] Example 12 A 1.5mm thick synthetic quartz glass is provided. A first Bessel beam and a second Bessel beam are generated sequentially, and the two beams are coaxially focused inside the quartz glass. The first Bessel beam has a wavelength of 355nm, a pulse width of 700fs, and a single pulse energy of 200μJ; the second Bessel beam has a wavelength of 405nm, a pulse width of 50μs, and a single pulse energy of 8mJ. The timing difference between the two beams is 15μs, and the difference in focal depth between the two beams is 0.2mm. The preset processing speed is 45μm / s, and the process is purged with argon gas at a pressure of 0.2MPa to obtain a micro-via with a diameter of 10μm.

[0076] Example 13 A 2mm thick monocrystalline sapphire crystal was used to generate a first Bessel beam and a second Bessel beam, which were coaxially focused within the sapphire crystal. The first Bessel beam had a wavelength of 1550nm, a pulse width of 10ps, and a single-pulse energy of 500μJ; the second Bessel beam had a wavelength of 1470nm, a pulse width of 70μs, and a single-pulse energy of 14mJ. The timing difference between the two beams was 45μs, and the difference in focal depth between the two beams was 0.3mm. The preset processing speed was 50μm / s, and the process was purged with argon gas at a pressure of 0.22MPa to obtain a micro-via with a diameter of 30μm.

[0077] Comparative Example 1 A 1mm thick borosilicate glass is provided. Only a first Bessel beam is generated and focused inside the borosilicate glass; a second Bessel beam is not generated. The first Bessel beam has a wavelength of 1064nm, a pulse width of 700fs, and a single pulse energy of 500μJ. The preset processing speed is 50μm / s, and argon gas at a pressure of 0.2MPa is used for purging during processing, aiming to obtain a micro-via with a diameter of 20μm.

[0078] Comparative Example 2 A 1mm thick borosilicate glass was provided. Only a second Bessel beam was generated and focused within the borosilicate glass, without generating a first Bessel beam. The second Bessel beam had a wavelength of 1030nm, a pulse width of 50ns, and a single-pulse energy of 5000μJ. The preset processing speed was 50μm / s, and the process was purged with argon gas at 0.2MPa pressure, attempting to obtain a 20μm diameter micro-via. Due to the lack of hole-forming effect from the first beam, the second beam could not effectively form a via, resulting in severe ablation pits on the material surface, failing to achieve penetration, and the processing failed.

[0079] Performance testing (1) Detection of aperture shape and depth-to-diameter ratio An Olympus OLS4100 laser confocal microscope was used. Five micropore samples were processed repeatedly for each process and directly tested. Two-dimensional morphological images of three cross-sections—the upper port, middle section, and lower port—were acquired along the depth direction of the through-hole. These images were then longitudinally stitched together using the equipment software to reconstruct the complete three-dimensional contour of the micropore. The pore diameter at each cross-section was measured (average of the major and minor diameters), the effective penetration depth was measured, and the depth-to-diameter ratio (effective pore depth / average pore diameter) was calculated. The average value of the five samples was taken as the final result.

[0080] (2) Detection of hole wall roughness Ra A Keyence VHX series ultra-depth-of-field 3D electron microscope and its matching roughness analysis module were used. The microporous sample was cut perpendicular to the hole axis to expose the cross-section. It was then sequentially ground and polished with sandpaper until a mirror finish was achieved, followed by ultrasonic cleaning with anhydrous ethanol. At magnifications of 2000x to 5000x, three measurement areas (upper, middle, and lower) were selected along the longitudinal direction of the hole wall. At least three morphology images were acquired for each area. The roughness analysis module was used to calculate the arithmetic mean deviation (Ra) of the profile. The average value of the data from each area was taken as the final Ra result for the micropore. The average value of five samples was then recorded.

[0081] (3) Defect observation (throughness and internal debris blockage detection) The ink penetration method combined with optical microscopy was used for observation. Water-based ink (viscosity 2–5 mPa·s) was prepared, and 20–50 μL was dropped onto the upper end of the micropore. White filter paper was placed at the lower end, and after standing for 30 seconds, the presence of ink penetration was observed on the filter paper. If a clear ink stain appeared on the filter paper and no obvious debris residue was observed inside the pore under the microscope, it was judged as "good penetration, clean interior"; if the ink stain was intermittent or shifted, it was judged as "internal blockage"; if no ink stain appeared, it was judged as "not penetrated"; if the ink abnormally diffused along the material surface, it was judged as "the presence of microcracks or pore wall defects". The penetration rate was recorded as "number of penetrations / total number".

[0082] The performance test results of the examples and comparative examples are shown in Table 1 below.

[0083] Table 1. Performance results of the examples and comparative examples The test results show that all embodiments achieved stable breakthroughs, with aperture deviations generally controlled within ±0.8 μm, indicating that the dual-beam processing scheme has good process adaptability on different materials. In samples with a thickness of approximately 1 mm, the effective aperture depth is close to the nominal material thickness, and the depth-to-diameter ratio is concentrated between 50:1 and 52:1, showing good data consistency. This indicates that when the timing difference and depth-to-focus difference of the dual beams fluctuate within the range of the claims, the process window is wide and will not significantly affect the aperture formation effect. Examples 8 and 9 further increased the thickness to 5 mm and 20 mm, respectively, and still obtained effective aperture depths of 4.96 mm and 19.85 mm, with depth-to-diameter ratios reaching 124:1 and 248:1, demonstrating that this method is also feasible for processing materials with large thicknesses.

[0084] Regarding the roughness of the pore walls, borosilicate glass has a roughness between 0.68 and 0.85 μm, quartz glass between 0.52 and 0.88 μm, and sapphire between 0.91 and 1.05 μm. Sapphire is more prone to microscale peeling when processed as a single crystal material, but no obvious continuous microcracks or thermal damage were found on the pore walls in all embodiments.

[0085] Comparative Example 1, using only the first Bessel beam, achieved an effective hole depth of only 0.65 mm, failing to reach the material thickness. The hole wall roughness increased to 1.95 μm, accompanied by numerous microcracks and orifice collapse. This indicates that while the first beam alone can form a modified channel, debris accumulation and residual stress severely restrict the processing quality. Comparative Example 2, using only the second Bessel beam, exhibited a noticeable taper in the hole, with the worst hole wall roughness reaching 2.35 μm. This demonstrates that without the guidance of the first beam pre-formed hole, high-energy pulses are prone to excessive ablation on the surface, making it difficult for energy to be effectively transmitted to the depth direction.

[0086] In general, in this application, the first Bessel beam forms a region of uniform energy deposition along the optical axis inside the transparent brittle material, completing the through-hole forming that penetrates the thickness of the material in one process. After the through-hole is initially formed, the second Bessel beam performs secondary modification on the hole wall along the same optical axis path. Throughout the entire process, the two Bessel beams do not require the introduction of chemical auxiliary means. The complete processing chain from forming to modification can be completed simply by matching the timing of the beam parameters and the spatial overlap. Finally, residual debris is removed by purging to obtain a high-quality transparent brittle material product including the through-hole.

[0087] Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples.

[0088] The above description is only a part or preferred embodiment of this application and should not be construed as limiting the scope of protection of this application. All equivalent structural transformations made using the content of this application specification under the overall concept of this application, or direct / indirect applications in other related technical fields, are included within the scope of protection of this application.

Claims

1. A laser processing method for through holes in a transparent brittle material, characterized in that, Includes the following steps: A first Bessel beam and a second Bessel beam are generated sequentially, and the first Bessel beam and the second Bessel beam are coaxially focused on a transparent and brittle material; Processed according to preset parameters, the first Bessel beam forms a through hole inside the transparent brittle material, and the second Bessel beam modifies the inner wall of the through hole along the through hole; Remove debris from the holes to obtain a finished transparent brittle material containing through holes; The light emission time of the first Bessel beam and the second Bessel beam differs by 10 microseconds to 100 microseconds, and the difference in focal depth between the first Bessel beam and the second Bessel beam is ≤0.5 mm.

2. The laser processing method for through holes in transparent brittle materials according to claim 1, characterized in that, The wavelengths of the first Bessel beam and the second Bessel beam are each selected from the range of 355nm to 1550nm, and the difference between the wavelengths of the first Bessel beam and the second Bessel beam is 20nm to 80nm.

3. The laser processing method for through holes in transparent brittle materials according to claim 2, characterized in that, The wavelength of the first Bessel beam is 1000nm~1080nm; And / or, the wavelength of the second Bessel beam is 1040nm~1100nm.

4. The laser processing method for through holes in transparent brittle materials according to claim 2, characterized in that, The single-pulse energy of the first Bessel beam is 100μJ~600μJ; And / or, the single-pulse energy of the second Bessel beam is 1mJ~20mJ.

5. The laser processing method for through holes in transparent brittle materials according to claim 1, characterized in that, The pulse width of the second Bessel beam is at least 10 times the pulse width of the first Bessel beam. 6 times.

6. The laser processing method for through holes in transparent brittle materials according to claim 5, characterized in that, The pulse width of the first Bessel beam is 700 fs to 15 ps, and the pulse width of the second Bessel beam is 10 μs to 100 μs.

7. The laser processing method for through holes in transparent brittle materials according to claim 1, characterized in that, The preset parameters include a processing speed of 40μm / s to 80μm / s.

8. The laser processing method for through holes in transparent brittle materials according to claim 1, characterized in that, The thickness of the transparent brittle material is 1mm to 20mm; And / or, the transparent brittle material includes at least one of glass, gem crystal, and transparent ceramic.

9. The laser processing method for through holes in transparent brittle materials according to claim 1, characterized in that, The removal of debris from the orifice includes purging with inert gas at a pressure of 0.1 MPa to 0.3 MPa.

10. A laser processing system for through holes in transparent brittle materials, characterized in that, The system is used to perform a laser processing method for through holes in transparent brittle materials as described in any one of claims 1 to 9, the system comprising: A laser emitting module, used to emit a first laser beam and a second laser beam; A conical lens module is used to shape the laser beam into a first Bessel beam and a second Bessel beam; A lens module is disposed in the output light path of the conical lens module and is used to adjust the focusing depth of the Bessel beam; A beam combiner module is located at the intersection of the outgoing optical paths of the first Bessel beam and the second Bessel beam, and is used to combine the first Bessel beam and the second Bessel beam into a coaxial beam. A focusing objective lens is disposed in the output optical path of the beam combiner and is used to focus the coaxial beam onto a transparent and brittle material.

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