Method for driving diamond wire to cut silicon wafer by using carbon fiber main roller

Abstract

The invention discloses a method for utilizing a carbon fiber main roller to drive a diamond wire to cut a silicon wafer, which relates to the field of silicon wafer cutting and comprises the following steps: cutting a silicon block by adopting a new diamond wire with a gradient structure until the cutting depth reaches the cutting depth; a new diamond wire of a gradient structure is adopted for cutting the silicon block till the cutting depth reaches the second preset depth; the generated old diamond wire is subjected to grading detection, and the qualified old diamond wire is selected to cut the silicon block until the cutting depth reaches a third preset depth; and a qualified old diamond wire is selected to cut the silicon block till the cutting depth reaches the fourth preset cutter-out and plate-in depth. According to the method, by utilizing the old diamond wire graded reuse and combining the diamond wire designed in a gradient structure and the dynamic wire speed adjusting model, efficient utilization of diamond wire consumables is achieved, the wire using amount of single-time cutting is reduced, the old wire which is originally abandoned is reasonably reused, the waste rate of core consumables is reduced, and the production cost is reduced. And collaborative optimization of the whole process is matched.

Description

Technical Field

[0001] This invention relates to the field of silicon wafer cutting, and in particular to a method for cutting silicon wafers using a carbon fiber main roller driven by a diamond wire. Background Technology

[0002] Solar-grade silicon wafers are thin sheets made with high-purity silicon as the core material, specifically used to manufacture solar cells. They convert sunlight into electrical energy through photoelectric conversion. Currently, solar-grade silicon wafers are mainly produced by cutting square monocrystalline silicon rods into thin sheets. Therefore, improving production efficiency, namely increasing the effective output rate of silicon materials per unit time, optimizing the cutting process to shorten processing time, and focusing on reducing non-silicon costs, has become a core issue in the industry and a key focus for enterprises to enhance their competitiveness.

[0003] In the field of photovoltaic silicon wafer cutting, silicon wafers are usually obtained by cutting silicon blocks with diamond wire. The main shaft drives the main roller to rotate, and the main roller then drives the diamond wire to perform the cutting operation. However, in the existing cutting process, diamond wire is a core consumable material, and the amount of wire used in a single cut is huge, which leads to increased costs. Therefore, it is necessary to use a silicon wafer cutting method that uses recyclable and graded old diamond wire. Summary of the Invention

[0004] The purpose of this invention is to provide a method for cutting silicon wafers using a carbon fiber main roller driven by a diamond wire cutter, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for cutting silicon wafers using a carbon fiber main roller driven by a diamond wire cutter, comprising: Step 1: Use a new diamond wire with a gradient structure to cut the silicon block until the cutting depth reaches the depth of penetration; Step 2: Use a new diamond wire with a gradient structure to cut the silicon block until the cutting depth reaches the second preset depth; Step 3: The old diamond wire produced in Step 1 is graded and inspected. Qualified old diamond wire is selected to cut the silicon block until the cutting depth reaches the third preset depth. Step 4: The old diamond wire generated in Step 2 is graded and inspected. Qualified old diamond wire is selected to cut the silicon block until the cutting depth reaches the fourth preset cutting depth. The entire cutting process is driven by the spindle to move the carbon fiber main roller, which in turn drives the diamond wire and uses coolant. It is combined with a four-stage dynamic line speed model, a tension and temperature dynamic adjustment system, and coolant flow adjustment. At the same time, the spindle torque threshold is set.

[0006] Preferably, the diameter of the new gradient structure diamond wire in steps one and two is 38 μm, and the diamond particles are fixed with a nickel-cobalt alloy binder. The diamond particle size is 8-10 μm. The new gradient structure diamond wire includes a high-density reinforced section and a conventional working section. The high-density reinforced section is set along the length of the diamond wire, and the diamond particle density in the high-density reinforced section is 1500 particles / cm², with the particles arranged in a spiral shape. The diamond particle density in the conventional working section is 1200 particles / cm², with the particles arranged in a uniform lattice. The transition zone length between the high-density reinforced section and the conventional working section is 0.02-0.04 cm, and there is a linear transition in particle density.

[0007] Preferably, the old diamond wire grading detection in steps three and four includes preprocessing, multi-dimensional detection, and grade determination; The pretreatment specifically includes cleaning the old diamond wire generated in steps one and two to remove surface silicon powder and coolant residue, drying it, and then cutting it into detection segments of 4-6 cm in length. The multi-dimensional detection specifically includes detecting the pre-treated old diamond wire, using a laser diameter gauge to detect the wire diameter uniformity, a scanning electron microscope to detect the diamond particle residue rate, the proportion of detached area and the sharpness of the cutting edge, and a roughness meter to detect the surface roughness of the wire. The grading process specifically involves classifying old diamond wire into three grades: Grade 1, Grade 2, and unqualified. Grade 1 wire is used for cutting at the third preset depth, Grade 2 wire is used for cutting at the fourth preset depth, and unqualified wire is directly recycled.

[0008] Preferably, the first-grade used diamond wire has a diamond particle residue rate of ≥80%, a detachment area ratio of ≤20%, a wire diameter wear of ≤2µm, a cutting edge sharpness of ≥0.8, and a surface roughness Ra of ≤0.3µm. The second-grade used diamond wire has a diamond particle residue rate of ≥70% and <80%, a detachment area ratio of ≤30% and >20%, a wire diameter wear of ≤3µm and >2µm, a cutting edge sharpness of ≥0.6 and <0.8, and a surface roughness Ra of ≤0.5µm and >0.3µm. The unqualified used diamond wire is below the second-grade standard.

[0009] Preferably, in the four-stage dynamic linear velocity model, the linear velocity of each stage is adapted to the gradient diamond wire segment, specifically including: S1: In the cutting stage, high-density reinforced section cutting with gradient diamond wire is used, and the wire speed is linearly increased from 10m / s to 13m / s. S2: During the stable entry stage, maintain a linear speed of 13-14 m / s and cut using the transition zone between the high-density reinforced section and the conventional working section; S3: The first stage of old diamond wire reuse, the wire speed is reduced to 12.8-13m / s to match the cutting efficiency of the first stage old diamond wire; S4: Second stage of old diamond wire reuse, the wire speed is further reduced to 12.6m / s, reducing the wear rate of the second stage old diamond wire.

[0010] Preferably, the tension temperature dynamic adjustment system specifically includes: SS1: Initial stages of steps one and two: large fluctuations in cutting load, tension set at 3.2±0.3N, temperature set at 20±0.5℃, when spindle torque > 28N. At m, the tension automatically increases by 0.2-0.3N, and the temperature decreases by 0.5-1℃; SS2: During the first and second steps: the tension is set to 3.0±0.2N, the temperature is set to 21±0.3℃, and the parameters are kept stable; SS3: Steps three and four: Reduce the old wire cutting force, set the tension to 3.3±0.3N, and set the temperature to 20.5±0.5℃. When the wire mark depth detection value is >6μm, reduce the tension by 0.1-0.2N and increase the temperature by 0.3-0.5℃. SS4: End of Step Four: Reduce load, set tension to 2.8±0.2N, and set temperature to 21.5±0.5℃.

[0011] Preferably, the depth of insertion in step one is 18% ± 2% of the total thickness of the silicon block, the second preset depth in step two is 48% ± 2% of the total thickness of the silicon block, the third preset depth in step three is 82% ± 2% of the total thickness of the silicon block, and the fourth preset depth of insertion into the board in step four is 100% of the total thickness of the silicon block. When switching depths at each stage, the tension and temperature dynamic adjustment system starts 0.5 seconds in advance and performs parameter pre-adjustment.

[0012] Preferably, the carbon fiber main roller adopts a coating and grooving process, which includes coating layer design, coating preparation, precision grooving, and post-processing. The grooving cross-section is U-shaped, the grooving width is 40±0.5um, the grooving depth is 25±0.5um, and the grooving spacing is 1.2±0.1mm. The coating layer in the coating and grooving process is made of WC-Co hard alloy material and is prepared by plasma spraying. The coating thickness is 50-80um and the bonding strength is ≥80MPa.

[0013] Preferably, the dynamic adjustment system for coolant flow rate and tension temperature, and the four-stage linear speed and diamond wire state linkage dynamic adjustment specifically include: In the initial stages of steps one and two: when the linear velocity increases, the coolant flow rate is set to 9±1L / min, and increases linearly with the increase in linear velocity. Specifically, for every 1m / s increase in linear velocity, the flow rate increases by 0.5L / min. At the same time, if the tension is ≥3.5N, the flow rate increases by an additional 0.3-0.5L / min. During the middle of steps one and two: When maintaining the linear speed, the coolant flow rate is set to 7±0.5L / min. If the temperature of the cutting area is >21.5℃, the flow rate will automatically increase by 0.5L / min. If the temperature is <20.5℃, the flow rate will decrease by 0.3L / min. Step 3: Cutting edge sharpness ≥ 0.8, coolant flow rate set to 8 ± 0.5 L / min, when the line mark depth detection value > 5 μm, increase the flow rate by 0.3 L / min; Step 4: The cutting edge sharpness is ≥0.6 and <0.8, and the coolant flow rate is set to 7.5±0.5L / min, which is 0.5L / min lower than the first-stage old diamond wire cutting flow rate; At the end of step four: the load gradually decreases, the coolant flow rate is set to 6±0.5L / min, and it decreases linearly as the cutting depth approaches 100%. Specifically, the flow rate decreases by 0.2L / min for every 5% depth, until the flow rate drops to 5L / min when the cutting is completed. When the silicon powder concentration is detected to be >50g / L, the coolant circulation filtration is activated, and the flow rate is increased by 0.8L / min to ensure smooth chip removal.

[0014] Preferably, the spindle torque setting threshold includes a normal threshold, a warning threshold, and an interruption threshold, wherein the normal threshold is a spindle torque ≤ 32N. m, the warning threshold is 32N m < spindle torque < 35N m, the interruption threshold is the spindle torque ≥38N When the warning threshold is reached, the tension will be increased by 0.2-0.3N, the temperature will be decreased by 0.5-1℃, and the coolant flow rate will be increased by 1L / min. The four-stage dynamic linear speed model maintains the current linear speed. If the torque does not fall back to the normal threshold within the first set time, the linear speed will be reduced by 0.2m / s. When the spindle torque continues to exceed the second set time within the warning threshold range, and the silicon wafer quality is detected online, the line mark depth and edge breakage are monitored in real time. If the line mark depth is >7μm or the edge breakage length is >50μm, the tension will be reduced by 0.1N and the flow rate will be increased by 0.3L / min until the torque falls back or the quality indicators return to normal.

[0015] The technical effects and advantages of this invention are as follows: (1) This invention utilizes the graded reuse of old diamond wire and combines the diamond wire with a gradient structure design and a dynamic wire speed adjustment model to achieve efficient utilization of diamond wire consumables, significantly reducing the amount of wire used in a single cut. At the same time, it allows the previously discarded old wire to be reused in a reasonable manner, reducing the waste rate of core consumables. Furthermore, with the synergistic optimization of the overall process, it reduces energy consumption during the cutting process, thereby significantly reducing non-silicon costs and overall production costs, and improving economic benefits. (2) By optimizing the configuration of linear speed parameters in each stage of cutting, this invention constructs a dynamic linear speed adjustment model, which shortens the total time of a single cut. At the same time, by coordinating the dynamic coupling adjustment of coolant flow rate and linear speed, the cutting rhythm is optimized, which helps to prevent ineffective energy consumption and time waste, and improves the unit time output efficiency of the equipment. (3) By adopting an innovative coating and grooving process for the carbon fiber main roller, the present invention optimizes the structural characteristics of the main roller, reduces the inertial momentum during the cutting process, and reduces the load impact during equipment operation by precisely controlling the main shaft torque, thereby reducing the wear of the main roller and related transmission components, extending the service life of the equipment, and reducing the related costs of equipment maintenance and replacement. (4) By setting up a tension and temperature dynamic adjustment system, the present invention can dynamically control the key parameters in the cutting process, effectively reduce the vibration of the wire and the load fluctuation in the cutting process, reduce the occurrence rate of defects such as wire marks and edge breakage on the silicon wafer surface, improve the appearance quality and dimensional accuracy of the silicon wafer, and ensure the stable production of high-grade silicon wafers. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the silicon wafer cutting process of the present invention; Figure 2 This is a schematic diagram of the four-stage dynamic linear velocity model of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention provides, for example Figures 1-2 The method shown includes the following specific steps for cutting silicon wafers using a carbon fiber main roller to drive a diamond wire cutter: Step 1: Use a new diamond wire with a gradient structure to cut the silicon block until the cutting depth reaches the depth of penetration; Step 2: Use a new diamond wire with a gradient structure to cut the silicon block until the cutting depth reaches the second preset depth; Step 3: The old diamond wire produced in Step 1 is graded and inspected. Qualified old diamond wire is selected to cut the silicon block until the cutting depth reaches the third preset depth. Step 4: The used diamond wire produced in Step 2 is graded and inspected. Qualified used diamond wire is selected to cut the silicon block until the cutting depth reaches the fourth preset blade entry depth. The entire cutting process is driven by the spindle-driven carbon fiber main roller, which in turn drives the diamond wire and uses coolant. This is combined with a four-stage dynamic linear speed model, a tension and temperature dynamic adjustment system, and coolant flow rate adjustment. A spindle torque threshold is also set. The coolant used is polyethylene glycol-based cutting fluid with a molecular weight of 400-600, containing 0.5%-1% nano-alumina abrasive particles (50-100nm in diameter). The abrasive particle surface is modified with a silane coupling agent, and the dispersion stability is ≥72h. The cutting fluid viscosity is 25-35mPa. s (25℃), surface tension ≤30mN / m, the cooling flow monitoring and regulation system includes a flow monitoring module, a flow regulation execution module and an auxiliary monitoring unit. The flow monitoring module uses an electromagnetic flow meter, installed at the outlet of the coolant main pipeline, to collect the current flow data in real time and transmit it to the central control module. The flow regulation execution module uses a proportional flow valve driven by a stepper motor, installed downstream of the electromagnetic flow meter, to receive instructions from the central control module to achieve precise flow regulation. The auxiliary monitoring unit includes a silicon powder concentration sensor (installed in the coolant return pipeline) and a pressure sensor (installed in the main pipeline to monitor the coolant pressure and avoid pressure fluctuations affecting flow stability). The above steps help reduce the diamond wire consumption from 10KM to 7KM (a reduction of 30%), and reduce the material cost by 0.12 yuan / piece through old wire reuse technology. The total cutting time is reduced by 5 minutes to 100 minutes (efficiency improvement of 4.76%), of which the time optimization of the cutting stage accounts for 62%. The silicon block is cut from an 830mm specification monocrystalline silicon rod or polycrystalline silicon rod.

[0019] Furthermore, the diameter of the new gradient structure diamond wire in steps one and two is 38 μm, and the diamond particles are fixed with a nickel-cobalt alloy binder. The diamond particle size is 8-10 μm. The new gradient structure diamond wire includes a high-density reinforced section and a conventional working section. The high-density reinforced section is set along the length of the diamond wire, and the diamond particle density in the high-density reinforced section is 1500 particles / cm², and the particles are arranged in a spiral shape. The diamond particle density in the conventional working section is 1200 particles / cm², and the particles are arranged in a uniform lattice. The transition zone length between the high-density reinforced section and the conventional working section is 0.02-0.04 cm, and there is a linear transition in particle density.

[0020] Furthermore, the old diamond wire grading detection in steps three and four includes preprocessing, multi-dimensional detection, and grade determination; The pretreatment specifically includes cleaning the old diamond wire generated in steps one and two to remove surface silicon powder and coolant residue, drying it, and then cutting it into 4-6cm long detection segments. The multi-dimensional inspection specifically includes inspecting the pre-treated old diamond wire, using a laser diameter gauge to detect the wire diameter uniformity, a scanning electron microscope to detect the diamond particle residue rate, the proportion of detached area and the sharpness of the cutting edge, and a roughness meter to detect the surface roughness of the wire. The grading process specifically involves classifying old diamond wire into three grades: Grade 1, Grade 2, and unqualified. Grade 1 wire is used for cutting at the third preset depth, Grade 2 wire is used for cutting at the fourth preset depth, and unqualified wire is directly recycled.

[0021] Specifically, Grade 1 used diamond wire is characterized by a diamond particle residue rate ≥80%, a detachment area ratio ≤20%, wire diameter wear ≤2µm, cutting edge sharpness ≥0.8, and surface roughness Ra ≤0.3µm. Grade 2 used diamond wire is characterized by a diamond particle residue rate ≥70% and <80%, a detachment area ratio ≤30% and >20%, wire diameter wear ≤3µm and >2µm, cutting edge sharpness ≥0.6 and <0.8, and surface roughness Ra ≤0.5µm and >0.3µm. Unqualified used diamond wire is below Grade 2 standards.

[0022] Furthermore, in the four-stage dynamic linear velocity model, the linear velocity at each stage is adapted to the gradient diamond wire segment, specifically including: S1: In the cutting stage, high-density reinforced section cutting with gradient diamond wire is used, and the wire speed is linearly increased from 10m / s to 13m / s. S2: During the stable entry stage, maintain a linear speed of 13-14 m / s and cut using the transition zone between the high-density reinforced section and the conventional working section; S3: The first stage of old diamond wire reuse, the wire speed is reduced to 12.8-13m / s to match the cutting efficiency of the first stage old diamond wire; S4: Second stage of old diamond wire reuse, the wire speed is further reduced to 12.6m / s, reducing the wear rate of the second stage old diamond wire.

[0023] Specifically, the tension temperature dynamic adjustment system includes: SS1: Initial stages of steps one and two: large fluctuations in cutting load, tension set at 3.2±0.3N, temperature set at 20±0.5℃, when spindle torque > 28N. At m, the tension automatically increases by 0.2-0.3N, and the temperature decreases by 0.5-1℃; SS2: During the first and second steps: the tension is set to 3.0±0.2N, the temperature is set to 21±0.3℃, and the parameters are kept stable; SS3: Steps three and four: Reduce the old wire cutting force, set the tension to 3.3±0.3N, and set the temperature to 20.5±0.5℃. When the wire mark depth detection value is >6μm, reduce the tension by 0.1-0.2N and increase the temperature by 0.3-0.5℃. SS4: End of Step Four: Reduce load, set tension to 2.8±0.2N, and set temperature to 21.5±0.5℃.

[0024] Furthermore, the tension and temperature dynamic adjustment system includes a tension detection module, a temperature detection module, a central control module, a tension adjustment execution module, and a temperature adjustment execution module. The tension detection module uses a high-precision tension sensor with a sampling frequency of 100Hz to collect diamond wire tension data in real time. The temperature detection module has three distributed temperature sensors set in the cutting area, located at the inlet, middle, and outlet ends, respectively, to collect ambient temperature and coolant temperature in real time. The central control module has a built-in PID adjustment algorithm, receives tension, temperature, spindle torque, and cutting depth signals, and outputs adjustment commands. The tension adjustment execution module uses a servo motor to drive the tension wheel. The temperature adjustment execution module includes a coolant temperature control device and a cutting area air-cooling device. The coolant temperature adjustment range is 18-24℃, and the air speed of the air-cooling device can be adjusted within the range of 0.5-2m / s. Furthermore, the cutting depth in step one is 18%±2% of the total thickness of the silicon block, the second preset depth in step two is 48%±2% of the total thickness of the silicon block, the third preset depth in step three is 82%±2% of the total thickness of the silicon block, and the fourth preset cutting depth in step four is 100% of the total thickness of the silicon block. When switching between the depths at each stage, the tension and temperature dynamic adjustment system starts 0.5s in advance and performs parameter pre-adjustment.

[0025] The carbon fiber main roller employs a coating and grooving process, with a U-shaped grooving cross-section, a grooving width of 40±0.5µm, a grooving depth of 25±0.5µm, and a grooving spacing of 1.2±0.1mm. The coating layer in this process uses WC-Co cemented carbide material and is prepared via plasma spraying. The coating thickness is 50-80µm, and the bonding strength is ≥80MPa. The coating and grooving process includes four core steps: coating design, coating preparation, precision grooving, and post-processing. The coating material system design uses WC-Co cemented carbide powder as the core raw material, adding 5%-8% TiC nanoparticles as a reinforcing phase, and incorporating 2%-3% Cr3C2 to improve coating adhesion. The powder particle size is controlled at 15-45µm, with a flowability ≥25s / 50g to ensure uniform spraying. The coating preparation process uses atmospheric plasma spraying with a spraying power set at 40-45kW and Ar-H2 plasma gas. Mixed gas, spraying distance 100-120mm, powder feeding rate 30-40g / min; before spraying, the carbon fiber main roller substrate is pre-treated by sandblasting, and the surface roughness Ra of the substrate is controlled at 3.2-6.3μm to enhance the mechanical bonding force between the coating and the substrate; the coating thickness is precisely controlled at 50-80μm, and the thickness uniformity deviation is ≤±5μm; precision groove design and processing: after the coating layer is cured, precision groove processing is performed using an ultra-hard diamond grinding wheel. The groove cross-section is an optimized U-shaped structure to avoid stress concentration leading to diamond wire wear; the groove width is 40±0.5um (compatible with 38um diameter diamond wire, with a 2um allowance). Assembly gap), groove depth 25±0.5um (ensuring diamond wire embedding depth is 65% of wire diameter, improving transmission stability), groove spacing 1.2±0.1mm (matching silicon wafer cutting thickness requirements); grooving process adopts ultrasonic vibration assisted cutting technology, vibration frequency 20-30kHz, amplitude 5-10μm, reducing processing burrs, groove wall surface roughness Ra≤0.8um; post-processing: after grooving, the coating layer is passivated by plasma nitriding to form a nitriding layer with a thickness of 1-2μm on the coating surface, increasing hardness to HRC70-75, and enhancing wear resistance by 30%; finally, cleaning and drying are performed, and ultrasonic cleaning can be used to remove processing residues.

[0026] Specifically, the coolant flow rate and tension temperature dynamic adjustment system, and the four-stage linear speed and diamond wire condition linkage dynamic adjustment system include: In the initial stages of steps one and two: when the linear velocity increases, the coolant flow rate is set to 9±1L / min. The flow monitoring module provides real-time feedback on the matching degree between the linear velocity and the flow rate, and the flow rate increases linearly and synchronously with the increase in linear velocity. This is achieved by the flow rate adjustment execution module controlled by the central control module. Specifically, for every 1m / s increase in linear velocity, the flow rate increases by 0.5L / min. At the same time, if the tension is ≥3.5N, the flow rate is increased by an additional 0.3-0.5L / min by receiving the tension sensor signal, which is beneficial for enhancing chip removal and cooling. During the middle of steps one and two: When maintaining the linear speed, the coolant flow rate is set to 7±0.5L / min. If the temperature of the cutting area is >21.5℃, the flow rate will automatically increase by 0.5L / min. If the temperature is <20.5℃, the flow rate will decrease by 0.3L / min. The central control module compares the temperature of the cutting area fed back by the temperature sensor with the set threshold, and then the flow rate adjustment module realizes dynamic fine-tuning. The flow rate monitoring module verifies the adjustment effect in real time. Step 3: The cutting edge sharpness is ≥0.8, the coolant flow rate is set to 8±0.5L / min, the central control module receives the line mark depth detection signal, and when the line mark depth detection value is >5μm, the flow rate is increased by 0.3L / min. The flow monitoring module continuously provides feedback on the adjusted flow rate to ensure the abrasive-assisted cutting effect. Step 4: The cutting edge sharpness is ≥0.6 and <0.8. The coolant flow rate is set to 7.5±0.5L / min, which is 0.5L / min lower than the first-stage old diamond wire cutting flow rate to avoid excessive abrasive erosion of the old wire. At the end of step four: The load gradually decreases, and the coolant flow rate is set to 6±0.5L / min, which decreases linearly as the cutting depth approaches 100%. Specifically, the flow rate decreases by 0.2L / min for every 5% increase in depth. The central control module controls the flow rate adjustment module based on the cutting depth sensor signal to achieve this until the cutting is completed and the flow rate drops to 5L / min. The flow rate monitoring module confirms the linear decreasing trend of the flow rate in real time to avoid sudden changes. Specifically, when the silicon powder concentration is detected to be >50g / L, the coolant circulation filtration is initiated, and the flow rate is increased by 0.8L / min. This is achieved synchronously through the central control module to ensure smooth chip removal. Simultaneously, the flow monitoring module ensures the flow rate remains stable at the target value until the silicon powder concentration is <40g / L, at which point the original flow rate is restored. The system also activates when the spindle torque sensor reports a torque >32N. When the torque reaches m, the central control module immediately instructs the flow regulation execution module to increase the flow rate by 1L / min. The flow monitoring module continuously monitors for 3 seconds. If the torque does not decrease, the flow rate is increased again by 0.5L / min. Every 10 seconds, the flow monitoring module compares the actual flow rate with the set flow rate. If the deviation is greater than 0.2L / min, the central control module automatically outputs a calibration command, which corrects the deviation through the flow regulation execution module to ensure the accuracy of flow control throughout the process.

[0027] Specifically, the spindle torque setting thresholds include a normal threshold, a warning threshold, and an interruption threshold. The normal threshold is a spindle torque ≤ 32N. m, the warning threshold is 32N m < spindle torque < 35N m, interruption threshold is spindle torque ≥38N When the warning threshold is reached, the central control module receives the torque detection signal and immediately triggers linkage adjustment, increasing the tension by 0.2-0.3N, decreasing the temperature by 0.5-1℃, and increasing the coolant flow rate by 1L / min. The four-stage dynamic linear speed model maintains the current linear speed. If the torque does not fall back to the normal threshold within the first set time, the linear speed decreases by 0.2m / s. When the spindle torque reaches the interruption threshold, the central control module immediately outputs a stop command, the equipment stops cutting and triggers an audible and visual alarm, and records parameters such as the current cutting depth and peak torque for troubleshooting. When the spindle torque exceeds the second set time within the warning threshold range, and the silicon wafer quality is detected online (a non-contact online detection system that communicates with the central control module), the specific detection implementation and linkage logic are as follows: During the cutting process, the depth of the line marks on the silicon wafer (perpendicular to the silicon wafer surface) is detected. The system detects both groove depth and edge chipping (notches or cracks at the edge of the silicon wafer). Laser triangulation is used to detect groove depth, and machine vision is used to detect edge chipping. Multi-sensor collaboration enables full-area coverage detection. The groove depth detection unit includes a semiconductor laser emitter, a CCD image sensor, and a signal processing module. The laser emitter is incident at a 45° angle to the silicon wafer surface, and the CCD sensor receives the reflected light perpendicularly, calculating the groove depth using triangulation. The edge chipping detection unit includes a high-resolution industrial camera and a ring LED light source. The camera is mounted on both sides of the cutting area, shooting at a 30° angle to the edge of the silicon wafer. The LED light source provides uniform illumination, reducing glare interference. The data processing module incorporates an image recognition algorithm to process the light and image signals collected by the sensors in real time, outputting groove depth values ​​and edge chipping length and location information. Detection trigger condition: When the spindle torque is within the warning threshold range (32N). m < torque < 35N m) If the detection time exceeds the second preset time, the central control module sends a start command to the silicon wafer quality inspection module, and the module immediately enters the online inspection state, maintaining a detection frequency of 10Hz; the line mark depth detection range is 0-20μm, with a detection accuracy of ±0.2μm; the edge chipping detection covers all edges of the silicon wafer, with a minimum identifiable edge chipping length of 5μm and a detection accuracy of ±1μm; the linkage control logic is: if the detected line mark depth is >7μm... If the chipped edge length is greater than 50μm, the data processing module immediately sends an abnormal signal to the central control module. The central control module further adjusts the process parameters: tension is reduced by 0.1N, coolant flow rate is increased by 0.3L / min, and the detection is repeated every 1 second until the line mark depth is ≤7μm and the chipped edge length is ≤50μm, or the spindle torque drops back to the normal threshold. If the standard is still not met after 3 consecutive adjustments, the enhanced adjustment of the spindle torque early warning control system is triggered. The laser emitter and CCD sensor of the line mark depth detection unit are symmetrically installed above the cutting area, 50-80mm away from the silicon wafer surface. The industrial camera and LED light source of the chipped edge detection unit are symmetrically installed on both sides of the carbon fiber main roller, 20-30mm away from the edge of the silicon wafer, to ensure no blind spots in the detection. After every 5 cuts, the module automatically starts the calibration program, comparing with a standard sample (with a known line mark depth of 5μm and no chipped edge). If the detection deviation is greater than 0.3μm, the algorithm parameters are automatically corrected. A calibration is performed before each daily cut. A comprehensive calibration ensures long-term testing accuracy. The module housing features a dustproof and waterproof structure with an internal electromagnetic shielding layer to prevent interference from silicon powder, coolant, and electromagnetic signals during the cutting process. The laser emitter and camera lens are equipped with automatic cleaning devices to prevent contaminants from affecting the testing results. Real-time monitoring of line mark depth and edge chipping is implemented. If the line mark depth > 7μm or the edge chipping length > 50μm, the tension is reduced by 0.1N and the flow rate is increased by 0.3L / min until the torque drops or the quality indicators return to acceptable levels. The spindle, the core transmission component connecting the drive motor and the carbon fiber main roller, can be made of 40CrNiMoA alloy with a nitrided surface. The spindle and carbon fiber main roller are connected by a key with an interference fit to ensure slip-free power transmission. A torque detection module with a strain gauge torque sensor is mounted on the spindle to collect the reaction torque signal experienced by the spindle during cutting in real time and transmit it to the central control module. When the torque drops to ≤30N under the warning threshold, the system will detect the torque loss. When m, the central control module controls each system parameter to gradually restore to the corresponding stage set value. The restoration process lasts for 2 seconds to avoid parameter sudden changes that could cause line vibration.

[0028] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for cutting silicon wafers using a carbon fiber main roller driven by a diamond wire cutter, characterized in that: The specific steps include the following: Step 1: Use a new diamond wire with a gradient structure to cut the silicon block until the cutting depth reaches the depth of penetration; Step 2: Use a new diamond wire with a gradient structure to cut the silicon block until the cutting depth reaches the second preset depth; Step 3: The old diamond wire produced in Step 1 is graded and inspected. Qualified old diamond wire is selected to cut the silicon block until the cutting depth reaches the third preset depth. Step 4: The old diamond wire generated in Step 2 is graded and inspected. Qualified old diamond wire is selected to cut the silicon block until the cutting depth reaches the fourth preset cutting depth. The entire cutting process is driven by the spindle to move the carbon fiber main roller, which in turn drives the diamond wire and uses coolant. It is combined with a four-stage dynamic line speed model, a tension and temperature dynamic adjustment system, and coolant flow adjustment. At the same time, the spindle torque threshold is set.

2. The method for cutting silicon wafers using a carbon fiber main roller to drive a diamond wire cutter according to claim 1, characterized in that: The new diamond wire with gradient structure in steps one and two has a wire diameter of 38 μm and uses a nickel-cobalt alloy binder to fix the diamond particles, with a particle size of 8-10 μm. The new diamond wire with gradient structure includes a high-density reinforced section and a conventional working section. The high-density reinforced section is set along the length of the diamond wire, and the diamond particle density in the high-density reinforced section is 1500 particles / cm², with the particles arranged in a spiral shape. The diamond particle density in the conventional working section is 1200 particles / cm², with the particles arranged in a uniform lattice. The transition zone length between the high-density reinforced section and the conventional working section is 0.02-0.04 cm, and there is a linear transition in particle density.

3. The method for cutting silicon wafers using a carbon fiber main roller to drive a diamond wire cutter according to claim 1, characterized in that: The old diamond wire grading and detection in steps three and four includes preprocessing, multi-dimensional detection, and grading determination. The pretreatment specifically includes cleaning the old diamond wire generated in steps one and two to remove surface silicon powder and coolant residue, drying it, and then cutting it into detection segments of 4-6 cm in length. The multi-dimensional detection specifically includes detecting the pre-treated old diamond wire, using a laser diameter gauge to detect the wire diameter uniformity, a scanning electron microscope to detect the diamond particle residue rate, the proportion of detached area and the sharpness of the cutting edge, and a roughness meter to detect the surface roughness of the wire. The grading process specifically involves classifying old diamond wire into three grades: Grade 1, Grade 2, and unqualified. Grade 1 wire is used for cutting at the third preset depth, Grade 2 wire is used for cutting at the fourth preset depth, and unqualified wire is directly recycled.

4. The method for cutting silicon wafers using a carbon fiber main roller to drive a diamond wire cutter according to claim 3, characterized in that: The first-grade used diamond wire is characterized by a diamond particle residue rate ≥80%, a detachment area ratio ≤20%, a wire diameter wear ≤2µm, a cutting edge sharpness ≥0.8, and a surface roughness Ra ≤0.3µm. The second-grade used diamond wire is characterized by a diamond particle residue rate ≥70% and <80%, a detachment area ratio ≤30% and >20%, a wire diameter wear ≤3µm and >2µm, a cutting edge sharpness ≥0.6 and <0.8, and a surface roughness Ra ≤0.5µm and >0.3µm. The unqualified used diamond wire is below the second-grade standard.

5. The method for cutting silicon wafers using a carbon fiber main roller driven by a diamond wire as described in claim 1, characterized in that: In the four-stage dynamic linear velocity model, the linear velocity of each stage is adapted to the gradient diamond wire segment, specifically including: S1: In the cutting stage, high-density reinforced section cutting with gradient diamond wire is used, and the wire speed is linearly increased from 10m / s to 13m / s. S2: During the stable entry stage, maintain a linear speed of 13-14 m / s and cut using the transition zone between the high-density reinforced section and the conventional working section; S3: The first stage of old diamond wire reuse, the wire speed is reduced to 12.8-13m / s to match the cutting efficiency of the first stage old diamond wire; S4: Second stage of old diamond wire reuse, the wire speed is further reduced to 12.6m / s, reducing the wear rate of the second stage old diamond wire.

6. The method for cutting silicon wafers using a carbon fiber main roller to drive a diamond wire cutter according to claim 1, characterized in that: The tension-temperature dynamic adjustment system specifically includes: SS1: Initial stages of steps one and two: large fluctuations in cutting load, tension set at 3.2±0.3N, temperature set at 20±0.5℃, when spindle torque > 28N. At m, the tension automatically increases by 0.2-0.3N, and the temperature decreases by 0.5-1℃; SS2: During the first and second steps: the tension is set to 3.0±0.2N, the temperature is set to 21±0.3℃, and the parameters are kept stable; SS3: Steps three and four: Reduce the old wire cutting force, set the tension to 3.3±0.3N, and set the temperature to 20.5±0.5℃. When the wire mark depth detection value is >6μm, reduce the tension by 0.1-0.2N and increase the temperature by 0.3-0.5℃. SS4: End of Step Four: Reduce load, set tension to 2.8±0.2N, and set temperature to 21.5±0.5℃.

7. The method for cutting silicon wafers using a carbon fiber main roller to drive diamond wire as described in claim 1, characterized in that: The depth of insertion in step one is 18% ± 2% of the total thickness of the silicon block; the second preset depth in step two is 48% ± 2% of the total thickness of the silicon block; the third preset depth in step three is 82% ± 2% of the total thickness of the silicon block; and the fourth preset depth of insertion into the board in step four is 100% of the total thickness of the silicon block. When switching depths at each stage, the tension and temperature dynamic adjustment system starts 0.5 seconds in advance and performs parameter pre-adjustment.

8. The method for cutting silicon wafers using a carbon fiber main roller to drive a diamond wire cutter according to claim 1, characterized in that: The carbon fiber main roller adopts a coating and grooving process, which includes coating design, coating preparation, precision grooving, and post-processing. The grooving cross-section is U-shaped, the grooving width is 40±0.5um, the grooving depth is 25±0.5um, and the grooving spacing is 1.2±0.1mm. The coating layer in the coating and grooving process is made of WC-Co hard alloy material and is prepared by plasma spraying. The coating thickness is 50-80um and the bonding strength is ≥80MPa.

9. The method for cutting silicon wafers using a carbon fiber main roller to drive a diamond wire cutter according to claim 1, characterized in that: The dynamic adjustment system for coolant flow rate, tension, and temperature, along with the four-stage linear speed and diamond wire condition linkage dynamic adjustment, specifically includes: In the initial stages of steps one and two: when the linear velocity increases, the coolant flow rate is set to 9±1L / min, and increases linearly with the increase in linear velocity. Specifically, for every 1m / s increase in linear velocity, the flow rate increases by 0.5L / min. At the same time, if the tension is ≥3.5N, the flow rate increases by an additional 0.3-0.5L / min. During the middle of steps one and two: When maintaining the linear speed, the coolant flow rate is set to 7±0.5L / min. If the temperature of the cutting area is >21.5℃, the flow rate will automatically increase by 0.5L / min. If the temperature is <20.5℃, the flow rate will decrease by 0.3L / min. Step 3: Cutting edge sharpness ≥ 0.8, coolant flow rate set to 8 ± 0.5 L / min, when the line mark depth detection value > 5 μm, increase the flow rate by 0.3 L / min; Step 4: The cutting edge sharpness is ≥0.6 and <0.8, and the coolant flow rate is set to 7.5±0.5L / min, which is 0.5L / min lower than the first-stage old diamond wire cutting flow rate; At the end of step four: the load gradually decreases, the coolant flow rate is set to 6±0.5L / min, and it decreases linearly as the cutting depth approaches 100%. Specifically, the flow rate decreases by 0.2L / min for every 5% depth, until the flow rate drops to 5L / min when the cutting is completed. When the silicon powder concentration is detected to be >50g / L, the coolant circulation filtration is activated, and the flow rate is increased by 0.8L / min to ensure smooth chip removal.

10. The method for cutting silicon wafers using a carbon fiber main roller driven by a diamond wire as described in claim 1, characterized in that: The spindle torque setting threshold includes a normal threshold, a warning threshold, and an interruption threshold. The normal threshold is a spindle torque ≤ 32N. m, the warning threshold is 32N m < spindle torque < 35N m, the interruption threshold is the spindle torque ≥38N When the warning threshold is reached, the tension will be increased by 0.2-0.3N, the temperature will be decreased by 0.5-1℃, and the coolant flow rate will be increased by 1L / min. The four-stage dynamic linear speed model maintains the current linear speed. If the torque does not fall back to the normal threshold within the first set time, the linear speed will be reduced by 0.2m / s. When the spindle torque continues to exceed the second set time within the warning threshold range, and the silicon wafer quality is detected online, the line mark depth and edge breakage are monitored in real time. If the line mark depth is >7μm or the edge breakage length is >50μm, the tension will be reduced by 0.1N and the flow rate will be increased by 0.3L / min until the torque falls back or the quality indicators return to normal.

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