A process for suppressing burrs in micro-nanostructure processing

Abstract

This invention provides a process for suppressing burr formation during the processing of micro / nano structures, relating to the field of workpiece micromachining. This method utilizes a UV-curable film as a protective layer, combined with solution cleaning and plasma cleaning to suppress burr generation. Specifically, a UV-curable protective layer is prepared before processing using UV curing and thermal baking. This protective layer suppresses lateral plastic flow of the boundary material of the workpiece, resulting in burrs only forming on the surface of the protective layer. The thickness of the protective layer is controlled by the spin coating speed, and the hardness is adjusted by controlling the UV curing and thermal baking times, based on the processing material and the dimensions of the micro / nano structure. Next, the micro / nano structure is processed using ultra-precision cutting. Finally, the protective layer is removed using a two-step cleaning method combining solution and plasma, resulting in a burr-free, smooth surface structure. This method achieves burr suppression adaptable to the cutting process of micro / nano structures made of various materials.

Description

Technical Field

[0001] This invention relates to the field of workpiece micro-machining technology, specifically a process method for suppressing the generation of burrs during the processing of micro-nano structures. Background Technology

[0002] Machining is the optimal manufacturing technology for complex micro / nano structures. In recent years, to adapt to the development of semiconductors and other industries, machining processes have been evolving towards the micro / nano scale. Burrs are material residues that appear on the workpiece surface, originating from the plastic deformation and flow caused by the cutting tool compressing the material during machining. Burrs reduce the surface quality of the workpiece and weaken the surface properties of micro / nano structures; therefore, suppressing or eliminating burrs in micro / nano structures is extremely important. Currently, methods for burr removal include manual removal, mechanical removal, chemical removal, heat treatment, pneumatic tool removal, and laser removal. However, these methods can damage the micro / nano structure and are therefore unsuitable for burr removal in micro / nano structures. During the fabrication of micro / nano structures, burr generation can be minimized by optimizing process parameters and improving tool quality, but these methods have limited effectiveness and cannot fundamentally prevent burr formation.

[0003] During machining, for ductile materials such as aluminum, copper, and polypropylene, the workpiece undergoes plastic deformation under the cutting force of the tool. The cut portion fractures into chips that are removed, but some boundary material flows to the side of the workpiece surface due to compression, forming burrs. To solve this problem, a protective layer can be prepared on the workpiece surface. This protective layer covers the workpiece surface below the machining surface, hindering the lateral plastic flow of the original boundary material during machining. Only the protective layer material forms burrs on the surface, thus suppressing burr formation. After machining, the protective layer can be removed through subsequent processing to obtain a burr-free, smooth surface structure.

[0004] However, existing protective layer cutting techniques use materials such as polymethyl methacrylate (PMMA) and paraffin wax as protective layers. First, the thickness of the protective layer should be related to the plastic flow characteristics of the material, the hardness of the protective layer, and the theoretical burr size. The coating thickness of PMMA and paraffin wax is difficult to control precisely. For micro / nano structure processing, the cutting depth is very small, and the accuracy of the protective layer thickness control directly affects the depth and aspect ratio of the processed micro / nano structure. Second, the optimal hardness of the protective layer is 70% to 90% of the hardness of the workpiece. Traditional protective layer materials such as PMMA and paraffin wax have constant hardness; for example, PMMA has a hardness of 60-75 Shore D, which limits the types of plastic materials it can handle. Paraffin wax has poor hardness and adhesion, failing to prevent the plastic flow and deformation of plastic materials, and its burr suppression effect is very limited. Finally, a cleaning process is needed to remove the protective layer to obtain a burr-free, smooth surface structure. For polymethyl methacrylate protective layers, the protective layer is usually cleaned with the organic solution acetone after cutting. However, acetone cannot completely remove the protective layer, so the residue will contaminate the workpiece surface and thus affect the surface quality.

[0005] Therefore, in order to suppress burrs in the processing of micro and nano structures of various materials, it is necessary to prepare a protective layer with adjustable thickness and hardness, and at the same time, to clean and treat the protective layer efficiently. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a process method for suppressing burr generation in micro-nano structure processing, solving the problems of burr generation in existing processing technologies and the cumbersome and poor adaptability of burr post-processing.

[0007] To achieve the above objectives, the present invention provides a technical solution through the following steps: a process for suppressing the generation of burrs in the fabrication of micro / nano structures.

[0008] S1. Surface pretreatment

[0009] First, the surface of the plastic material workpiece is cleaned and dried.

[0010] S2. Spin-coating UV adhesive protective layer

[0011] UV adhesive is spin-coated onto the surface of the workpiece using a spin coater to form a UV curing protective layer. The thickness of the UV curing protective layer is 2-30μm by controlling the spin coating speed and time.

[0012] S3. UV curing and heat drying

[0013] The spin-coated workpiece is placed in a UV curing machine to cure the UV protective layer by ultraviolet light. The curing time is 10-40 seconds. Then, it is heat-baked at a temperature of 150-200℃ for 5-10 minutes to adjust the hardness of the photoresist protective layer.

[0014] S4. Machining

[0015] The processed workpiece is machined using methods including but not limited to single-point turning, milling, high-speed flying cutting and ultrasonic vibration-assisted cutting. The machined structure must be a non-adjacent structure containing a boss.

[0016] S5. Solution immersion treatment

[0017] Immerse the processed workpiece in photoresist cleaning solution for 10 minutes;

[0018] S6. Plasma Treatment

[0019] The workpieces after being immersed in the solution were treated using an oxygen plasma device.

[0020] S7. Final Surface Treatment

[0021] After cleaning the workpiece to completely remove the UV curing protective layer, and then drying it, a burr-free, smooth finished workpiece can be obtained.

[0022] Preferably, in step S2, when the workpiece to be processed is a material with poor adhesion to UV adhesive, the workpiece surface is first subjected to an adhesion enhancement treatment before spin coating. The adhesion enhancement treatment includes, but is not limited to, electroplating, thermal spraying, and vapor deposition. The UV curing protective layer includes, but is not limited to, UV photoresist used in photolithography processes and UV adhesive used for bonding and encapsulation.

[0023] Preferably, the processing structure in step S4 includes, but is not limited to, holes, trapezoidal grooves, and serpentine grooves.

[0024] Preferably, in step S5, the photoresist cleaning agent includes, but is not limited to, organic solvents, acidic or alkaline photoresist cleaning agents.

[0025] Preferably, in step S6, the plasma equipment includes, but is not limited to, plasma jets and plasma chambers, and the processing atmosphere can be atmospheric or vacuum.

[0026] Preferably, step S6 is as follows:

[0027] The workpiece after immersion treatment was placed in a vacuum plasma chamber, and O2 plasma was excited. High-energy particles reacted with the UV curing protective layer through chemical reaction to generate gaseous reactants, thereby removing the protective layer. The radio frequency power supply was 13.56MHz with an input power of 600W. O2 and CF4 were used as reactant gases with a flow rate of 200sccm O2 + 100sccm CF4 and a treatment time of 15min.

[0028] This invention provides a process method for suppressing burr formation during the fabrication of micro / nano structures. It has the following beneficial effects:

[0029] 1. This invention controls the thickness of the protective layer by controlling the spin coating speed and time of the UV adhesive, and controls the hardness of the protective layer by controlling the photocuring and baking time, thereby preparing a protective layer with controllable hardness to prevent the lateral plastic flow of boundary materials during the micro-nano structure processing and the formation of burrs. It is applicable to a variety of processed materials.

[0030] 2. This invention utilizes a two-step high-efficiency cleaning process combining solvent and plasma. First, most of the UV-cured protective layer is removed through solution immersion, significantly saving the cost and time of subsequent plasma treatment. Then, oxygen plasma is used to further enhance the cleaning ability, resulting in a more significant cleaning effect. Compared to cleaning with acidic or alkaline solutions, which may corrode the surface, plasma cleaning does not damage the processed structure, resulting in higher surface quality and achieving highly efficient and clean removal of the residual protective layer. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the process flow of the present invention. Detailed Implementation

[0032] 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.

[0033] Example 1:

[0034] like Figure 1 As shown, this embodiment of the invention provides a process method for suppressing the generation of burrs in the fabrication of micro-nano structures, comprising the following steps:

[0035] S1. Surface pretreatment

[0036] First, the surface of the plastic material workpiece is cleaned and dried.

[0037] S2. Spin-coating UV adhesive protective layer

[0038] A UV-curing protective layer is formed by spin-coating UV adhesive onto the surface of the workpiece using a spin coater. The thickness of the UV-curing protective layer is maintained at 30 μm by controlling the spin-coating speed and time. To ensure the UV-curing protective layer's function in suppressing burrs, the layer thickness needs to be controlled at three times the burr size. The burr size in the cutting process is usually 10 μm, so the protective layer thickness needs to be adjusted according to the processing material and the thickness of the burrs generated in the specific process. When the workpiece is made of a material with poor adhesion to the UV adhesive, the workpiece surface is first subjected to an adhesion enhancement treatment before spin-coating. The adhesion enhancement treatment includes, but is not limited to, electroplating, thermal spraying, and vapor deposition. The UV-curing protective layer includes, but is not limited to, UV photoresist used in photolithography processes and UV adhesive used for bonding and encapsulation.

[0039] S3. UV curing and heat drying

[0040] The spin-coated workpiece is placed in a UV curing machine to cure the UV-cured protective layer under ultraviolet light for 40 seconds, followed by heat drying at 200℃ for 10 minutes. To ensure the UV-cured protective layer's burr suppression function, its hardness needs to be controlled. Insufficient UV curing time will result in an excessively low hardness, failing to achieve the burr suppression and transfer function. To maximize burr suppression, the protective layer hardness should be controlled to be 70% to 90% of the workpiece's hardness. Depending on the workpiece material and micro / nano structure size, the UV curing and heat drying times are controlled to adjust the protective layer hardness, ultimately achieving a hardness between 45 and 90 Shore D.

[0041] S4. Machining

[0042] The processed workpiece is then machined using methods including, but not limited to, single-point turning, milling, high-speed flying cutting, and ultrasonic vibration-assisted cutting. To ensure the applicability of the process, the cutting structure must be a non-adjacent structure containing a plane to ensure that burrs can be transferred to the protective layer. The machining structure includes, but is not limited to, holes, trapezoidal grooves, and serpentine grooves.

[0043] S5. Solution immersion treatment

[0044] After processing, the workpiece is immersed in a photoresist cleaning agent for 10 minutes. For UV-curable protective layer materials, the main component is an organic polymer. The photoresist cleaning agents used include, but are not limited to, inorganic solvents and acidic or alkaline reagents. Depending on the workpiece material, to avoid damage to the processed structure due to acid or alkali corrosion, solvents such as acetone or alcohol are often used to remove the protective layer material. Simultaneously, to improve processing efficiency, an ultrasonic cleaning device can be used during the solution immersion process.

[0045] S6. Plasma Treatment

[0046] The workpiece after immersion treatment is placed in a vacuum plasma chamber. O2 is used as the reactant gas and CF4 as the auxiliary gas. O2 plasma is excited in the vacuum chamber using a radio frequency power supply via capacitive coupling. The main component of the UV-cured protective layer is carbon-containing organic matter. High-energy particles in the plasma react chemically with the protective layer to generate CO2 and other gases, which are then discharged, thus achieving a cleaning effect and removing the UV-cured protective layer. This process does not require the introduction of Ar as a medium gas. The plasma cleaning effect is optimal when O2 and CF4 are introduced in a 2:1 ratio; therefore, the gas flow rate is set to 200 sccm O2 + 100 sccm CF4. The radio frequency power supply is set to 13.56 MHz with an output power of 600 W. When the protective layer thickness is 30 μm, it can be completely removed in 15 minutes. The plasma equipment includes, but is not limited to, plasma jets and plasma chambers. The treatment atmosphere can be atmospheric or vacuum. Depending on the cleaning area, plasma chambers are more efficient at processing large areas of the workpiece; plasma jets are relatively flexible and suitable for cleaning complex structures that are difficult to clean, or for cleaning workpieces that are too large to fit into the vacuum plasma chamber.

[0047] S7. Final Surface Treatment

[0048] After cleaning the workpiece to completely remove the UV curing protective layer, and then drying it, a burr-free, smooth finished workpiece can be obtained.

[0049] Since the formation of burrs is related to the inherent properties of the workpiece material, it is difficult to fundamentally avoid their formation during processing. Therefore, through steps S2 and S3, a UV-cured protective layer with adjustable hardness and thickness is prepared. The UV-cured protective layer is used as a medium to cover the workpiece surface under the processing surface, thereby suppressing the lateral flow of boundary material during the micro-nano structure processing and thus achieving the purpose of suppressing the formation of burrs on the workpiece surface.

[0050] Through steps S5 and S6, a two-step wet-dry cleaning process using solvent and plasma is employed. First, immersion in the solution removes most of the UV-cured protective layer, significantly reducing the cost and time of subsequent plasma treatment. Then, oxygen plasma further enhances the cleaning ability, resulting in a more significant cleaning effect. Compared to cleaning with acidic or alkaline solutions, which may corrode the surface, plasma cleaning does not damage the processed structure, resulting in higher surface quality.

[0051] Example 2:

[0052] like Figure 1 As shown, this embodiment of the invention provides a process method for suppressing the generation of burrs in the fabrication of micro-nano structures, comprising the following steps:

[0053] S1. Surface pretreatment

[0054] First, the surface of the plastic material workpiece is cleaned and dried.

[0055] S2. Spin-coating UV adhesive protective layer

[0056] A UV-curing protective layer is formed by spin coating UV adhesive onto the surface of the workpiece using a spin coater. The thickness of the UV-curing protective layer is kept within 2 μm by controlling the spin coating speed and time. When the workpiece is made of a material with poor adhesion to the UV adhesive, the workpiece surface is first subjected to an adhesion enhancement treatment before spin coating. The adhesion enhancement treatment includes, but is not limited to, electroplating, thermal spraying, and vapor deposition. The UV-curing protective layer includes, but is not limited to, UV photoresist used in photolithography processes and UV adhesive used for bonding and encapsulation.

[0057] S3. UV curing and heat drying

[0058] The spin-coated workpiece is placed in a UV curing machine to cure the UV protective layer by ultraviolet light for 10 seconds. Then, it is baked at 150°C for 5 minutes.

[0059] S4. Machining

[0060] The processed workpiece is then machined using methods including, but not limited to, single-point turning, milling, high-speed flying cutting, and ultrasonic vibration-assisted cutting. To ensure the applicability of the process, the cutting structure must be a non-adjacent structure containing a plane to ensure that burrs can be transferred to the protective layer. The machining structure includes, but is not limited to, holes, trapezoidal grooves, and serpentine grooves.

[0061] S5. Solution immersion treatment

[0062] The processed workpiece is immersed in a photoresist cleaning agent for 10 minutes. The photoresist cleaning agent used includes, but is not limited to, inorganic solvents and acidic or alkaline reagents. To improve processing efficiency, an ultrasonic cleaning device can be used during the solution immersion process.

[0063] S6. Plasma Treatment

[0064] The workpiece after immersion treatment is placed in a vacuum plasma chamber. O2 is used as the reactant gas and CF4 as the auxiliary gas. O2 plasma is excited in the vacuum chamber using a radio frequency power supply via capacitive coupling. The main component of the UV-cured protective layer is carbon-containing organic matter. High-energy particles in the plasma react chemically with the protective layer to generate CO2 and other gases, which are then discharged, thus achieving a cleaning effect and removing the UV-cured protective layer. This process does not require the introduction of Ar as a medium gas. The plasma cleaning effect is optimal when O2 and CF4 are introduced in a 2:1 ratio; therefore, the gas flow rate is set to 200 sccm O2 + 100 sccm CF4. The radio frequency power supply is set to 13.56 MHz with an output power of 600 W. When the protective layer thickness is 30 μm, it can be completely removed in 15 minutes. The plasma equipment includes, but is not limited to, plasma jets and plasma chambers. The treatment atmosphere can be atmospheric or vacuum.

[0065] S7. Final Surface Treatment

[0066] After cleaning the workpiece to completely remove the UV curing protective layer, and then drying it, a burr-free, smooth finished workpiece can be obtained.

[0067] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for suppressing burr generation during micro / nano structure fabrication, characterized in that: Includes the following steps: S1. Surface pretreatment First, the surface of the plastic material workpiece is cleaned and dried. S2. Spin-coating UV adhesive protective layer UV adhesive is spin-coated onto the surface of the workpiece using a spin coater to form a UV curing protective layer. The thickness of the UV curing protective layer is 2-30μm by controlling the spin coating speed and time. S3. UV curing and heat drying The spin-coated workpiece is placed in a UV curing machine to cure the UV protective layer by ultraviolet light. The curing time is 10-40 seconds. Then, it is heat-baked at a temperature of 150-200℃ for 5-10 minutes to adjust the hardness of the photoresist protective layer. S4. Machining The processed workpiece is machined using methods including but not limited to single-point turning, milling, high-speed flying cutting and ultrasonic vibration-assisted cutting. The machined structure must be a non-adjacent structure containing a boss. S5. Solution immersion treatment Immerse the processed workpiece in photoresist cleaning solution for 10 minutes; S6. Plasma Treatment The workpieces after being immersed in the solution were treated using an oxygen plasma device; S7. Final processing of table and text entries After cleaning the workpiece to completely remove the UV curing protective layer, and then drying it, a burr-free, smooth finished workpiece can be obtained.

2. The process method for suppressing burr generation in micro / nano structure fabrication according to claim 1, characterized in that: In step S2, when the workpiece to be processed is a material with poor adhesion to UV adhesive, the workpiece surface is first subjected to an adhesion enhancement treatment before spin coating. The adhesion enhancement treatment includes, but is not limited to, electroplating, thermal spraying, and vapor deposition. The UV curing protective layer includes, but is not limited to, UV photoresist used in photolithography processes and UV adhesive used for bonding and encapsulation.

3. The process method for suppressing burr generation in micro / nano structure fabrication according to claim 1, characterized in that: The machining structures in step S4 include, but are not limited to, holes, trapezoidal grooves, and serpentine grooves.

4. The process method for suppressing burr generation in micro / nano structure fabrication according to claim 1, characterized in that: In step S5, the photoresist cleaning agent includes, but is not limited to, organic solvents, acidic or alkaline photoresist cleaning agents.

5. The process method for suppressing burr generation in micro / nano structure fabrication according to claim 1, characterized in that: In step S6, the plasma equipment includes, but is not limited to, plasma jets and plasma chambers, and the processing atmosphere is atmospheric or vacuum.

6. The process method for suppressing burr generation in micro / nano structure fabrication according to claim 1, characterized in that: The specific steps of S6 are as follows: The workpiece after immersion treatment was placed in a vacuum plasma chamber, and O2 plasma was excited. High-energy particles reacted with the UV curing protective layer through chemical reaction to generate gaseous reactants, thereby removing the protective layer. The radio frequency power supply was 13.56MHz with an input power of 600W. O2 and CF4 were used as reactant gases with a flow rate of 200sccm O2 + 100sccm CF4 and a treatment time of 15min.

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