A glass substrate anti-cracking laser drilling method
By forming a seed copper layer on a glass substrate and performing a blackening treatment, combined with the optimization of laser drilling parameters, the problems of cracks and low energy absorption rate during laser drilling of glass substrates were solved, achieving high-quality laser drilling results.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZIBO CORE MATERIAL INTEGRATED CIRCUIT CO LTD
- Filing Date
- 2026-01-16
- Publication Date
- 2026-07-31
AI Technical Summary
Laser drilling of glass substrates presents problems such as high defect rate of hole edge cracks, low roundness, and low laser energy absorption rate.
A seed copper layer is formed on the surface of a glass substrate by magnetron sputtering and then blackened to enhance laser energy absorption. Combined with optimized laser drilling parameters, including adjusting laser power and pulse time, a thermal stress buffer layer is formed to prevent cracking.
It significantly improves the roundness and laser energy absorption rate of laser drilling, reduces the defect rate of hole edge cracks, and enhances the quality of laser drilling.
Smart Images
Figure CN121696573B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of IC packaging substrate technology, specifically to a method for preventing cracking of glass substrates using laser drilling. Background Technology
[0002] Traditional packaging substrates typically use organic resin substrates. However, with the increasing demand for higher frequency / high speed signal transmission, the market has validated that using glass substrates instead of resin substrates can achieve lower dielectric loss, extremely low transmission loss, high frequency adaptability, and electrical consistency in terms of electrical performance. In terms of physical and mechanical properties, it can achieve an ultra-flat surface, stronger dimensional stability, and greater mechanical strength. In terms of thermal management, it can achieve high temperature stability, adjustable thermal expansion, and high heat dissipation efficiency.
[0003] Micro-hole processing on glass substrates includes laser drilling, wet etching, and sandblasting. Among these, wet etching suffers from low precision and severe lateral etching, while sandblasting presents significant problems due to poor hole shape consistency. However, direct laser drilling on glass substrates also presents the following issues:
[0004] Glass is highly brittle, and thermal stress concentration leads to edge cracks (>80% defect rate).
[0005] The finished product has low roundness (<85%).
[0006] The laser energy absorption rate is low (the glass substrate has high light transmittance), so increasing the power is necessary to avoid thermal damage. Summary of the Invention
[0007] This application provides a method for preventing cracking in glass substrates using laser drilling, in order to solve or partially solve the problems mentioned in the background art.
[0008] This application provides a method for preventing cracking in glass substrates using laser drilling, comprising the following steps:
[0009] S100: Perform magnetron sputtering metallization on the glass substrate to form a seed copper layer on the surface of the glass substrate;
[0010] S200: The surface of the seed copper layer is blackened to improve surface roughness and enhance the light absorption rate of laser drilling;
[0011] S300: Laser drilling is performed on the blackened glass substrate;
[0012] The thickness of the seed copper layer is 2.5±0.2um, and the surface roughness of the seed copper layer after blackening treatment is Ra0.5-1.2um.
[0013] Preferably, the specific process for magnetron sputtering metallization of the glass substrate in step S100 is as follows:
[0014] S101: Pre-treatment of the glass substrate, including surface cleaning, surface activation and preheating, and preparation of the vacuum system;
[0015] S102: Target and parameter settings: Use a copper target with a purity of ≥99.99% and an oxygen content of <10ppm; sputtering power of 300W, ranging from 100 to 500W; target-substrate distance is fixed at 4–6cm to ensure uniform deposition.
[0016] S103: Pre-sputtering and deposition. During pre-sputtering, the argon flow rate is 24 mL / s, and the target surface is bombarded for 10 minutes to remove the oxide layer. Magnetic field control: The annular magnetic field strength of the planar magnetron target is 0.02–0.05 T, which constrains the cycloidal motion of electrons and improves the ionization rate.
[0017] S104: Deposition process, Ar + Ion bombardment of copper target, sputtering copper atoms vertically deposited onto substrate, thickness controlled at 2–3 μm; dynamic uniformity guaranteed, planetary drive of substrate holder to avoid film thickness deviation; real-time monitoring of gas pressure and target cooling water temperature to prevent thermal deformation;
[0018] S105: Annealing strengthening, annealing treatment at 200–250℃ promotes stress release in the copper layer and improves adhesion.
[0019] Preferably, the specific method for pretreating the glass substrate in step S101 is as follows:
[0020] Cleaning: The glass substrate is ultrasonically cleaned with acidic / alkaline solutions to remove oil and dust.
[0021] Surface activation: argon or oxygen plasma bombardment for 5–15 minutes to improve surface energy and adhesion;
[0022] Preheat the glass substrate to 350°C.
[0023] Preferably, the method for blackening the seed copper layer is as follows: chemical oxidation first forms a dark red cuprous oxide layer, and then a black copper oxide layer is formed. The process selection is as follows:
[0024]
[0025] in, As an oxidizing agent, As a catalyst, Provide an alkaline medium.
[0026] Preferably, the specific process for blackening the surface of the seed copper layer in step S200 is as follows:
[0027] Degreasing tank: using Daniel's degreasing agent, 80-120ml / L, temperature: 30-40℃;
[0028] Pickling tank: Use sulfuric acid solution, 170-200 g / L;
[0029] Blackening tank: temperature 85-95℃, NaClO2 concentration 35-60g / L, Na3PO4 concentration 9-23g / L, NaOH concentration 35-40g / L, pH value > 12.5;
[0030] Pre-drying tank: Temperature: 115-125℃, Processing time: >180s;
[0031] Drying tank: Temperature: 115-125℃, Processing time: >900s.
[0032] Preferably, in step S300, when performing laser drilling on the blackened glass substrate, the laser pulse parameters are optimized compared to direct laser drilling. The specific method is as follows:
[0033] S301: Adjust the laser power, reducing it by 10%-15%;
[0034] S302: Perform gradient optimization on the laser pulse duration Plus, as follows:
[0035] Reduce the duration and frequency of the initial pulse;
[0036] Maintain the mid-term pulse reference duration, reduce the number of repetitions, and reduce the gradient of the segmented fine-tuning values to achieve a gradient effect of gradual rise, steady flow, and gradual fall.
[0037] Use an extremely short pulse of 2-3µs to finish and trim the edge of the orifice;
[0038] S303: Reduce the mask size by 10%-15%.
[0039] Preferably, in step S300, the specific parameters for optimizing the laser pulse are as follows:
[0040] The mask size is 3.6mm, and the power is 9.5W.
[0041] The initial pulse is 8µs, and it is repeated once.
[0042] The reference duration of the intermediate pulse is 30µs. The ratio of the rising edge / stable segment / falling edge of the pulse is set in a 7.5 / 7 / 3 ratio and repeated twice.
[0043] Compared with the prior art, the beneficial effects of this application are as follows:
[0044] In this application, a seed copper layer is obtained by magnetron sputtering metallization, which serves as a thermal stress buffer layer for laser drilling. The ductility of copper is used to disperse the thermal shock of the laser, avoid cracks at the hole opening, and provide a carrier for the blackening process. The blackening treatment of the seed copper layer increases the surface roughness, enhances the laser energy coupling efficiency, improves the laser absorption rate, and allows for uniform heat diffusion, reducing local thermal stress and enhancing the roundness. Attached Figure Description
[0045] The present application will be further described below with reference to the accompanying drawings and embodiments.
[0046] Figure 1 This is a schematic diagram of the method flow of this application.
[0047] Figure 2 This is a schematic diagram of quality defects under a high-magnification microscope after direct laser drilling of a glass substrate.
[0048] Figure 3 This is a schematic diagram under a high-powered microscope after laser drilling of a glass substrate using the method described in this application.
[0049] Figure 4 A schematic diagram illustrating the roundness of direct laser drilling and laser drilling using the method described in this application.
[0050] Figure 5 This is a schematic diagram of the sputtered copper layer surface after blackening in this application.
[0051] Figure 6 This table provides a comparison of parameters between the method described in this application and direct laser drilling.
[0052] Figure 7 This is a schematic diagram illustrating the implementation of the method described in this application. Detailed Implementation
[0053] The specification and claims use certain terms to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The term "comprising" throughout the specification and claims is an open-ended term and should be interpreted as "comprising but not limited to." "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error.
[0054] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "horizontal", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.
[0055] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0056] Example 1
[0057] like Figure 1 and Figure 7 As shown, this application provides a method for preventing cracking in glass substrates using laser drilling, which specifically includes the following steps:
[0058] S100: Perform magnetron sputtering metallization on the glass substrate to form a seed copper layer on the surface of the glass substrate;
[0059] S200: The surface of the seed copper layer is blackened to improve surface roughness and enhance the light absorption rate of laser drilling;
[0060] S300: Laser drilling is performed on the blackened glass substrate.
[0061] Traditional packaging substrates typically use organic resin substrates. However, with the increasing demand for higher frequency / high-speed signal transmission, the market has validated that using glass substrates instead of resin substrates can achieve lower dielectric loss, extremely low transmission loss, high frequency adaptability, and electrical consistency in terms of electrical performance. In terms of physical and mechanical properties, it achieves ultra-flat surfaces, stronger dimensional stability, and greater mechanical strength. In terms of thermal management, it achieves high-temperature stability, adjustable thermal expansion, and high heat dissipation efficiency. Micro-hole processing on glass substrates includes laser drilling, wet etching, and sandblasting drilling. Among these, wet etching has low precision and severe lateral etching, while sandblasting drilling has poor hole shape consistency, presenting significant problems. However, direct laser drilling on glass substrates also presents the following issues:
[0062] Glass is highly brittle, and thermal stress concentration leads to edge cracks (>80% defect rate).
[0063] The finished product has low roundness (<85%).
[0064] The laser energy absorption rate is low (the glass substrate has high light transmittance), so increasing the power is necessary to avoid thermal damage.
[0065] like Figure 2 The image shows a high-magnification microscope illustration of quality defects (hole cracks / poor roundness) after direct laser drilling on a glass substrate. Based on comprehensive analysis, optimizing the laser drilling method is a more suitable technical solution.
[0066] In this application, a seed copper layer is obtained through magnetron sputtering metallization, which serves as a thermal stress buffer layer for laser drilling. The ductility of copper is used to disperse the thermal shock of the laser, avoid cracks at the hole opening, and provide a carrier for the blackening process. The blackening treatment of the seed copper layer increases the surface roughness, enhances the laser energy coupling efficiency, and increases the laser absorption rate to >95% (the laser absorption rate on the glass substrate is <30%). Heat is evenly diffused, reducing local thermal stress.
[0067] like Figure 3 The image shown is a photograph of the laser hole after laser drilling using the method of this application.
[0068] Specifically, the thickness of the seed copper layer is 2.5±0.2um, and the process capability index CPK>1.67. Actual testing has determined that when the seed copper layer thickness is <2um, the heat conduction is insufficient and cannot completely suppress cracking; when the seed copper layer thickness is >3um, the cost increases and resources are wasted.
[0069] Specifically, the method for blackening the seed copper layer is as follows: chemical oxidation first forms a dark red cuprous oxide layer, and then a black copper oxide layer is formed. The process selection is as follows:
[0070]
[0071] in, As an oxidizing agent, As a catalyst, It does not participate in the direct reaction, but provides an alkaline medium.
[0072] Specifically, the surface roughness of the seed copper layer after blackening treatment is Ra 0.5-1.2 μm. Figure 5 The image shown is a schematic diagram of the sputtered copper layer surface after blackening in this application.
[0073] Through the two steps of magnetron sputtering and blackening treatment in this application, actual testing shows that the roundness of the laser-drilled hole is >85%. The heat dissipation effect of the blackening layer avoids energy concentration, resulting in zero pore cracks. The copper layer absorbs and extends to release stress, preventing cracks from extending into the glass. Figure 4 As shown in the figure, 1-POR is a schematic diagram of the roundness of the hole directly drilled on the glass substrate, and 2-NEW is a schematic diagram of the roundness of the hole drilled using the method of this application.
[0074] Specifically, in step S100, the specific process for magnetron sputtering metallization of the glass substrate is as follows:
[0075] S101: Pre-treatment of the glass substrate, including surface cleaning, surface activation and preheating, and preparation of the vacuum system;
[0076] S102: Target material and parameter settings: Use a copper target with a purity of ≥99.99% (4N) and an oxygen content of <10ppm; sputtering power of 300W (medium power optimization point), ranging from 100 to 500W; target-substrate distance is fixed at 4–6cm to ensure deposition uniformity;
[0077] S103: Pre-sputtering and deposition. During pre-sputtering, the argon flow rate is 24 mL / s, and the target surface is bombarded for 10 minutes to remove the oxide layer. Magnetic field control: The annular magnetic field strength of the planar magnetron target is 0.02–0.05 T, which constrains the cycloidal motion of electrons and improves the ionization rate.
[0078] S104: Deposition process, Ar + Ion bombardment of copper target, sputtering copper atoms vertically deposited onto substrate, thickness controlled at 2–3 μm; dynamic uniformity guaranteed, substrate frame planetary drive (rotation + revolution) to avoid film thickness deviation; real-time monitoring of gas pressure (±0.1 Pa) and target cooling water temperature (15–25 ° C) to prevent thermal deformation.
[0079] S105: Annealing strengthening, annealing treatment at 200–250℃ promotes stress release in the copper layer and improves adhesion.
[0080] Specifically, the method for pre-treating the glass substrate in step S101 is as follows:
[0081] Cleaning: The glass substrate is ultrasonically cleaned with acidic / alkaline solutions to remove oil and dust.
[0082] Surface activation: argon or oxygen plasma bombardment for 5–15 minutes to improve surface energy and adhesion;
[0083] Preheat the glass substrate to 350°C.
[0084] Specifically, in step S200, the specific process for blackening the surface of the seed copper layer is as follows:
[0085] Degreasing tank: using Daniel's degreasing agent, 80-120ml / L, temperature: 30-40℃;
[0086] Pickling tank: Use sulfuric acid solution, 170-200 g / L;
[0087] Blackening tank: temperature 85-95℃, NaClO2 concentration 35-60g / L, Na3PO4 concentration 9-23g / L, NaOH concentration 35-40g / L, pH value > 12.5;
[0088] Pre-drying tank: Temperature: 115-125℃, Processing time: >180s;
[0089] Drying tank: Temperature: 115-125℃, Processing time: >900s.
[0090] Specifically, in step S300, when performing laser drilling on the blackened glass substrate, the laser pulse parameters are optimized compared to direct laser drilling. The specific method is as follows:
[0091] S301: Adjust the laser power, reducing it by 10%-15%;
[0092] S302: Perform gradient optimization on the laser pulse duration Plus, as follows:
[0093] Reduce the duration and frequency of the initial pulse;
[0094] Maintain the mid-term pulse reference duration, reduce the number of repetitions, but reduce the gradient of the segmented fine-tuning value to achieve a gradient effect of gradual rise, steady flow, and gradual fall;
[0095] Use an extremely short pulse (2-3us) to finish and trim the edges of the hole to avoid residual burrs in the copper layer;
[0096] S303: Reduce the mask size by 10%-15%.
[0097] like Figure 6 The table shown is a comparison of parameters between the method of this application and direct laser drilling. In the figure, Mask size is the mask size, which is the size of the mask opening during laser drilling and determines the basic size of the drilling; Power is the power, which is the energy intensity of the laser output; Pulse is the pulse, which is the combination of "duration × number of times" of the laser pulse. For example, 26us*2 means "a 26-microsecond pulse repeated twice", 30(9 / 7 / 4)us*4 represents the intermediate pulse adjusted in stages, with a base duration of 30us, and (9 / 7 / 4) represent the ratio of the rising edge / stable segment / falling edge of the pulse, respectively, repeated 4 times.
[0098] Depend on Figure 6It is known that the typical gradient for direct laser drilling is: an initial pulse of 26µs, repeated twice, a reference duration of 30µs for the intermediate pulse, and the ratio of the rising edge / stable segment / falling edge of the pulse set in a 9 / 7 / 4 ratio, repeated 4 times, with a mask size of 4.2mm and a power of 11W. In the method of this application, the initial pulse is 8µs, repeated once, the reference duration of the intermediate pulse is 30µs, and the ratio of the rising edge / stable segment / falling edge of the pulse is set in a 7.5 / 7 / 3 ratio, repeated twice. The operation of using an extremely short pulse (2-3µs) to finish the process in this application is omitted in the figure. The mask size is 3.6mm and the power is 9.5W.
[0099] This application utilizes the high absorption rate of the blackened layer to quickly "open holes" based on lower power and a short initial pulse, avoiding excessive initial energy that could cause copper layer melting and overflow. It also reduces the mid-pulse slope to match the thermal diffusion rhythm of the copper layer, reducing local stress. Finally, an extremely short pulse is used to finish the process, trimming the hole edge and avoiding residual burrs in the copper layer. This optimizes the laser drilling effect while reducing energy consumption.
[0100] The embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this application.
Claims
1. A method of crack-free laser drilling of a glass substrate, characterized by, Includes the following steps: S100: Perform magnetron sputtering metallization on the glass substrate to form a seed copper layer on the surface of the glass substrate; S200: The surface of the seed copper layer is blackened to improve surface roughness and enhance the light absorption rate of laser drilling; S300: Laser drilling is performed on the blackened glass substrate; The thickness of the seed copper layer is 2.5±0.2um, and the surface roughness of the seed copper layer after blackening treatment is Ra0.5-1.2um; In step S100, the specific process for magnetron sputtering metallization of the glass substrate is as follows: S101: Pre-treatment of the glass substrate, including surface cleaning, surface activation and preheating, and preparation of the vacuum system; S102: Target and parameter settings: Use a copper target with a purity of ≥99.99% and an oxygen content of <10ppm; sputtering power of 300W, ranging from 100 to 500W; target-substrate distance is fixed at 4–6cm to ensure uniform deposition. S103: Pre-sputtering and deposition. During pre-sputtering, the argon flow rate is 24 mL / s, and the target surface is bombarded for 10 minutes to remove the oxide layer. Magnetic field control: The annular magnetic field strength of the planar magnetron target is 0.02–0.05 T, which constrains the cycloidal motion of electrons and improves the ionization rate. S104: Deposition process, Ar + Ion bombardment of copper target, sputtering copper atoms vertically depositing the substrate, thickness control 2-3 μm; dynamic uniformity guarantee, planetary transmission of the substrate holder, avoiding film thickness deviation; real-time monitoring of gas pressure and target cooling water temperature to prevent thermal deformation; S105: Annealing strengthening, annealing treatment at 200–250℃ promotes stress release in the copper layer and improves adhesion; The method for blackening the seed copper layer is as follows: chemical oxidation first forms a dark red cuprous oxide layer, and then a black copper oxide layer is formed. The process selection is as follows: in, As an oxidizing agent, As a catalyst, Provide an alkaline medium; In step S200, the specific process for blackening the surface of the seed copper layer is as follows: Degreasing tank: using Daniel's degreasing agent, 80-120ml / L, temperature: 30-40℃; Pickling tank: Use sulfuric acid solution, 170-200 g / L; Blackening tank: temperature 85-95℃, NaClO2 concentration 35-60g / L, Na3PO4 concentration 9-23g / L, NaOH concentration 35-40g / L, pH value > 12.5; Pre-drying tank: Temperature: 115-125℃, Processing time: >180s; Drying tank: Temperature: 115-125℃, Processing time: >900s; In step S300, when performing laser drilling on the blackened glass substrate, the laser pulse parameters are optimized compared to direct laser drilling. The specific method is as follows: S301: Adjust the laser power, reducing it by 10%-15%; S302: Perform gradient optimization on the laser pulse duration Plus, as follows: Reduce the duration and frequency of the initial pulse; Maintain the mid-term pulse reference duration, reduce the number of repetitions, and reduce the gradient of the segmented fine-tuning values to achieve a gradient effect of gradual rise, steady flow, and gradual fall. Use an extremely short pulse of 2-3µs to finish and trim the edge of the orifice; S303: Reduce mask size by 10%-15%; In step S300, the specific parameters for optimizing the laser pulse are as follows: The mask size is 3.6mm, and the power is 9.5W. The initial pulse is 8µs, and it is repeated once. The reference duration of the intermediate pulse is 30µs. The ratio of the rising edge / stable segment / falling edge of the pulse is set in a 7.5 / 7 / 3 ratio and repeated twice.
2. The method for preventing cracking in glass substrates using laser drilling according to claim 1, characterized in that: In S101, the specific method for pre-treating the glass substrate is as follows: Cleaning: The glass substrate is ultrasonically cleaned with acidic / alkaline solutions to remove oil and dust. Surface activation: argon or oxygen plasma bombardment for 5–15 minutes to improve surface energy and adhesion; Preheat the glass substrate to 350°C.