Etching process of metal radiating fin

Abstract

The invention belongs to the technical field of metal etching, and particularly relates to an etching process of a metal radiating fin, which comprises the steps of metal plate pretreatment, photoresist coating, exposure and development, primary etching, secondary fine etching, photoresist removal and post-treatment. The method specifically comprises the following steps that firstly, a metal plate is pretreated and cleaned, specifically, the metal plate to be etched is put into a cleaning solution containing a surfactant to be subjected to ultrasonic cleaning, oil stains, dust and other impurities on the surface of the plate are removed, the temperature of the cleaning solution is controlled to range from 40 DEG C to 60 DEG C, and the ultrasonic cleaning time ranges from 10 min to 20 min; degreasing: the cleaned metal plate is immersed in a degreasing agent for degreasing treatment, and grease on the surface is further removed; the concentration of the degreasing agent is 5-10%, and the temperature is controlled to be 50-70 DEG C; and micro-etching: carrying out micro-etching treatment on the degreased metal plate so as to increase the roughness of the surface of the plate and improve the contact area and the reaction activity of the etching liquid and the metal surface.

Description

Technical Field

[0001] The invention belongs to the technical field of metal etching, and in particular relates to an etching process for a metal heat sink. Background Art

[0002] Etching, as a precision machining method, offers a new approach for manufacturing metal heat sinks. However, existing etching processes still have shortcomings in terms of etching accuracy, uniformity, environmental friendliness, and recyclability of the etching solution. For example, over- and under-etching are common during the etching process, making it difficult to ensure the dimensional accuracy and surface quality of the heat sink. Etching solutions contain large amounts of heavy metals and hazardous substances, causing serious environmental pollution. Furthermore, the etching solution has a short service life, and frequent replacement increases production costs. Summary of the Invention

[0003] The purpose of the present invention is to provide an etching process for a metal heat sink, which adopts a combination of preliminary etching and secondary fine etching to improve etching accuracy and uniformity, and manufacture metal heat sinks with complex shapes and fine structures, while reducing pollution to the environment, improving the recycling rate of etching solution, and reducing production costs.

[0004] The technical solutions adopted by the present invention are as follows:

[0005] A metal heat sink etching process includes: metal plate pretreatment, photoresist coating, exposure and development, preliminary etching, secondary fine etching, photoresist removal and post-processing; specifically, the following steps:

[0006] Step 1: Pretreatment of metal sheets

[0007] Cleaning: Place the metal sheet to be etched in a cleaning solution containing a surfactant for ultrasonic cleaning to remove impurities such as oil, dust, etc. on the surface of the sheet. The temperature of the cleaning solution is controlled at 40-60°C and the ultrasonic cleaning time is 10-20 minutes.

[0008] Degreasing: Immerse the cleaned metal sheet in a degreasing agent for degreasing to further remove grease on the surface; the concentration of the degreasing agent is 5-10%, and the temperature is controlled at 50-70℃;

[0009] Micro-etching: Micro-etching is performed on the degreased metal sheet to increase the surface roughness of the sheet, improve the contact area and reaction activity between the etching solution and the metal surface. The micro-etching solution uses a dilute sulfuric acid solution with a concentration of 2-5%;

[0010] Step 2: Apply photoresist

[0011] Select photoresist: Choose the appropriate photoresist according to the material of the metal sheet and etching requirements;

[0012] Coating photoresist: evenly coating the photoresist on the surface of the pre-treated metal sheet;

[0013] Baking: After coating the photoresist, place the metal sheet in an oven for baking to solidify the photoresist. The baking temperature is 80-100°C and the time is 10-20 minutes.

[0014] Step 3: Exposure and Development

[0015] Exposure: Place the metal plate coated with photoresist under the photolithography machine and expose it through the mask. The exposure light source uses ultraviolet light. The exposure time is adjusted according to the characteristics of the photoresist and the pattern of the mask, generally 10-30 seconds;

[0016] Development: The exposed metal sheet is placed in a developer to remove the unexposed photoresist, exposing the metal surface to be etched. The developer is an alkaline solution with a concentration of 0.5-2% and the development time is 1-3 minutes. After development, rinse with deionized water and then dry.

[0017] Step 4: Preliminary Etching

[0018] Prepare the preliminary etching solution: The preliminary etching solution is mainly composed of copper chloride, hydrochloric acid and a small amount of additives;

[0019] Preliminary etching process parameters: Place the developed metal sheet into the preliminary etching tank, control the temperature of the etching solution at 35-45°C, and the etching time is 3-8 minutes. During the preliminary etching process, stir the etching solution through a stirring device to ensure the uniformity of etching. The purpose of preliminary etching is to quickly remove most of the metal layer that needs to be etched, laying the foundation for subsequent secondary fine etching.

[0020] Recycling of preliminary etching solution: During the preliminary etching process, the etching solution is filtered through a filtering device to remove etching products and impurities, and then the filtered etching solution is returned to the preliminary etching tank for continued use. At the same time, the components in the etching solution are regularly replenished to maintain the concentration and performance stability of the etching solution.

[0021] Step 5: Second fine etching

[0022] Prepare secondary fine etching solution: The secondary fine etching solution is optimized based on the primary etching solution;

[0023] Secondary fine etching process parameters: Place the metal sheet after preliminary etching into the secondary fine etching tank, control the temperature of the etching solution at 40-50°C, and the etching time is 2-5 minutes. During the secondary fine etching process, adopt a gentler stirring method, such as low-speed stirring or pulse stirring, to further improve the uniformity and accuracy of etching. The purpose of secondary fine etching is to finely process the metal surface after preliminary etching, remove the residual metal layer, and achieve the dimensional accuracy and surface quality required by the design.

[0024] Recycling of secondary fine etching solution: Similar to the primary etching solution, the secondary fine etching solution is also filtered and recycled through a filtration device, and the components in the etching solution are regularly replenished to ensure the stable performance of the etching solution.

[0025] Step 6: Remove the photoresist

[0026] After the secondary fine etching is completed, the metal heat sink is placed in a degumming solution to remove the remaining photoresist. The degumming solution uses organic solvents such as acetone, ethanol, etc. The degumming time is 5-10 minutes. After degumming, it is rinsed with deionized water and then dried.

[0027] Step 7: Post-processing

[0028] Cleaning: Place the metal heat sink after removing the photoresist into a cleaning tank containing a cleaning agent to clean it and remove residual impurities and degumming liquid on the surface;

[0029] Passivation treatment: passivation treatment is performed on the cleaned metal heat sink to improve the corrosion resistance of the heat sink;

[0030] Drying: After passivation, rinse the metal heat sink with deionized water and then place it in an oven for drying;

[0031] Furthermore, the photoresist coating method can adopt conventional coating methods such as spin coating and spray coating.

[0032] Furthermore, the preliminary etching solution formula is as follows: the concentration of copper chloride is 80-120 g / L, the concentration of hydrochloric acid is 40-60 g / L, the additives mainly play the role of promoting etching reaction and inhibiting over-etching, and the total concentration of the additives is 0.5-2 g / L.

[0033] Furthermore, the formula of the secondary fine etching solution is as follows: the content of the corrosion inhibitor and the surfactant is increased on the basis of the preliminary etching solution formula, the concentration of copper chloride is adjusted to 100-150g / L, the concentration of hydrochloric acid is 50-70g / L, the concentration of the corrosion inhibitor is 1-3g / L, and the concentration of the surfactant is 0.5-2g / L. The corrosion inhibitor can effectively control the etching rate and avoid the occurrence of over-etching; the surfactant can improve the wettability of the etching solution and make the etching more uniform.

[0034] Furthermore, in the step 2 of coating the photoresist, the process uses positive photoresist, which has good resolution and etching resistance.

[0035] The technical effects achieved by the present invention are:

[0036] The present invention can achieve high-precision etching by combining primary etching and secondary fine etching. The primary etching quickly removes most of the metal layer, improving etching efficiency; the secondary fine etching finely processes the surface, ensuring etching accuracy.

[0037] The present invention adopts different etching solution formulas and process parameters in the primary etching and secondary fine etching processes respectively, and ensures etching uniformity through a stirring device and a filtering circulation system;

[0038] The etching solution used in the present invention contains additives and corrosion inhibitors, which can effectively suppress over-etching during the etching process and reduce etching solution consumption. At the same time, through the recycling of the etching solution, the discharge of the etching solution is reduced, and the pollution to the environment is reduced, thus meeting environmental protection requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic flow diagram of the present invention; DETAILED DESCRIPTION

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0041] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0042] See also Figure 1 As shown, the present invention provides an etching process for a metal heat sink, comprising:

[0043] Step 1: Pretreatment of metal sheets

[0044] An aluminum alloy sheet measuring 100 mm x 100 mm x 1 mm was selected as the metal sheet to be etched. The sheet was ultrasonically cleaned in a cleaning solution containing 2% surfactant at 50°C for 15 minutes. The sheet was then immersed in an 8% degreasing agent and degreased at 60°C for 8 minutes. Finally, the sheet was micro-etched in a 3% dilute sulfuric acid solution for 2 minutes.

[0045] Step 2: Apply photoresist

[0046] A positive photoresist was evenly applied to the pretreated metal surface using spin coating at a speed of 2500 rpm for 45 seconds to a thickness of 2 μm. After coating, the plate was placed in an oven and baked at 90°C for 15 minutes.

[0047] Step 3: Exposure and Development

[0048] A metal sheet coated with photoresist is placed under a photolithography machine and exposed to ultraviolet light through a pre-designed mask for 20 seconds. After exposure, the sheet is placed in a 1% alkaline developer for 2 minutes, then rinsed with deionized water and dried.

[0049] Step 4: Preliminary Etching

[0050] The initial etching solution formula is: 100g / L copper chloride, 50g / L hydrochloric acid, and 1g / L total additive concentration. The developed metal sheet is placed in the initial etching tank. The etching solution temperature is controlled at 40°C and the etching time is 5 minutes. During the initial etching process, the etching solution is stirred using a stirring device. Simultaneously, the etching solution is filtered through a filtration device to remove etching products and impurities, and the etching solution is regularly replenished.

[0051] Step 5: Second fine etching

[0052] The secondary fine etching solution formula is: 120g / L copper chloride, 60g / L hydrochloric acid, 2g / L corrosion inhibitor, and 1g / L surfactant. After the initial etching, the metal sheet is placed in the secondary fine etching tank. The etching solution temperature is controlled at 45°C and the etching time is 3 minutes. During the secondary fine etching process, low-speed stirring is used. The etching solution is filtered and recycled through a filtration device, and the components of the etching solution are regularly replenished.

[0053] Step 6: Remove the photoresist

[0054] After the secondary fine etching is completed, the metal heat sink is placed in an acetone degumming solution for 8 minutes. After degumming, it is rinsed with deionized water and dried.

[0055] Step 7: Post-processing

[0056] After removing the photoresist, place the metal heat sink in a cleaning tank containing a detergent at 50°C for 8 minutes. Then, place the heat sink in an 8% chromate passivation solution for 2 minutes. Finally, rinse with deionized water and dry in an oven at 90°C for 15 minutes.

[0057] The present invention achieves high-precision etching by combining primary etching with secondary fine etching. Primary etching rapidly removes the majority of the metal layer, improving etching efficiency; secondary fine etching finely processes the surface, ensuring etching precision. The present invention utilizes different etching solution formulations and process parameters during the primary and secondary fine etching processes, respectively, and ensures etching uniformity through a stirring device and a filtration circulation system. The etching solution formulation employed in the present invention contains additives and corrosion inhibitors, effectively suppressing over-etching during the etching process and reducing etching solution consumption. Furthermore, recycling the etching solution reduces etching solution emissions, minimizing environmental pollution and meeting environmental protection requirements.

[0058] The foregoing is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are also within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained herein shall, unless otherwise specified or limited, be implemented in accordance with conventional means in the art.

Claims

1. A metal heat sink etching process, characterized in that: The process includes: pretreatment of the metal sheet, coating of photoresist, exposure and development, preliminary etching, secondary fine etching, removal of photoresist and post-processing; specifically includes the following steps: Step 1: Pretreatment of metal sheets Cleaning: Place the metal sheet to be etched in a cleaning solution containing a surfactant for ultrasonic cleaning to remove impurities such as oil, dust, etc. on the surface of the sheet. The temperature of the cleaning solution is controlled at 40-60°C and the ultrasonic cleaning time is 10-20 minutes. Degreasing: Immerse the cleaned metal sheet in a degreasing agent for degreasing to further remove grease on the surface; the concentration of the degreasing agent is 5-10%, and the temperature is controlled at 50-70℃; Micro-etching: Micro-etching is performed on the degreased metal sheet to increase the roughness of the sheet surface, improve the contact area and reaction activity of the etching solution and the metal surface. The micro-etching solution uses a dilute sulfuric acid solution with a concentration of 2-5%; Step 2: Apply photoresist Select photoresist: Choose the appropriate photoresist according to the material of the metal sheet and etching requirements; Coating photoresist: evenly coating the photoresist on the surface of the pre-treated metal sheet; Baking: After coating the photoresist, place the metal sheet in an oven for baking to cure the photoresist. The baking temperature is 80-100°C and the time is 10-20 minutes. Step 3: Exposure and Development Exposure: Place the metal plate coated with photoresist under the photolithography machine and expose it through the mask. The exposure light source uses ultraviolet light. The exposure time is adjusted according to the characteristics of the photoresist and the pattern of the mask, generally 10-30 seconds; Development: The exposed metal sheet is placed in a developer for development to remove the unexposed photoresist portion and expose the metal surface to be etched. The developer uses an alkaline solution with a concentration of 0.5-2% and a development time of 1-3 minutes. After development, rinse with deionized water and then dry. Step 4: Preliminary Etching Prepare the preliminary etching solution: The preliminary etching solution is mainly composed of copper chloride, hydrochloric acid and a small amount of additives; Initial etching process parameters: Place the developed metal sheet into the initial etching tank, control the temperature of the etching solution at 35-45°C, and the etching time is 3-8 minutes. During the initial etching process, stir the etching solution through a stirring device to ensure the uniformity of the etching. The purpose of the initial etching is to quickly remove most of the metal layer that needs to be etched, laying the foundation for the subsequent secondary fine etching. Recycling of the initial etching solution: During the initial etching process, the etching solution is filtered through a filtration device to remove etching products and impurities, and then the filtered etching solution is returned to the initial etching tank for continued use. At the same time, the components in the etching solution are regularly replenished to maintain the concentration and performance stability of the etching solution; Step 5: Second fine etching Prepare secondary fine etching solution: The secondary fine etching solution is optimized based on the primary etching solution; Secondary fine etching process parameters: Place the metal sheet after the initial etching into the secondary fine etching tank, control the temperature of the etching solution at 40-50°C, and the etching time is 2-5 minutes. During the secondary fine etching process, adopt a more gentle stirring method, such as low-speed stirring or pulse stirring, to further improve the uniformity and accuracy of etching. The purpose of secondary fine etching is to finely process the metal surface after the initial etching, remove the residual metal layer, and achieve the dimensional accuracy and surface quality required by the design; Recycling of secondary fine etching solution: Similar to the primary etching solution, the secondary fine etching solution is also filtered and recycled through a filtration device, and the components in the etching solution are regularly replenished to ensure the stable performance of the etching solution; Step 6: Remove the photoresist After the secondary fine etching is completed, the metal heat sink is placed in a degumming solution to remove the remaining photoresist. The degumming solution uses an organic solvent such as acetone, ethanol, etc. The degumming time is 5-10 minutes. After degumming, it is rinsed with deionized water and then dried. Step 7: Post-processing Cleaning: Place the metal heat sink after removing the photoresist into a cleaning tank containing a cleaning agent to clean it and remove residual impurities and degumming liquid on the surface; Passivation treatment: passivation treatment is performed on the cleaned metal heat sink to improve the corrosion resistance of the heat sink; Drying: After passivation, rinse the metal heat sink with deionized water and then place it in an oven for drying.

2. The etching process for a metal heat sink according to claim 1, wherein: The photoresist coating method can adopt conventional coating methods such as spin coating and spray coating.

3. The etching process for a metal heat sink according to claim 1, wherein: The preliminary etching solution formula is as follows: the concentration of copper chloride is 80-120 g / L, the concentration of hydrochloric acid is 40-60 g / L, the additives mainly play the role of promoting etching reaction and inhibiting over-etching, and the total concentration of the additives is 0.5-2 g / L.

4. The etching process for a metal heat sink according to claim 1, wherein: The secondary fine etching solution formula comprises: a primary etching solution formula with the addition of a corrosion inhibitor and a surfactant; the concentration of cupric chloride is adjusted to 100-150 g / L; the concentration of hydrochloric acid is 50-70 g / L; the concentration of the corrosion inhibitor is 1-3 g / L; and the concentration of the surfactant is 0.5-2 g / L. The corrosion inhibitor can effectively control the etching rate and avoid over-etching; and the surfactant can improve the wettability of the etching solution and make etching more uniform.

5. The etching process for a metal heat sink according to claim 1, wherein: In the second step of coating the photoresist, the process uses positive photoresist, which has good resolution and etching resistance.

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