Double-sided different-depth etching process for heat dissipation plate

Abstract

The invention belongs to the technical field of heat dissipation plate etching, and particularly relates to a heat dissipation plate double-sided different-depth etching process which comprises the following steps: cleaning: putting a heat dissipation plate in an alkaline cleaning agent, soaking for 10-15 minutes at the temperature of 50-60 DEG C to remove impurities such as oil stains and dust on the surface, and then washing for multiple times by using deionized water to ensure that the surface is clean and free of residues; and b) micro-etching: carrying out micro-etching treatment on the surface of the heat dissipation plate for 3-5 minutes by using a micro-etching solution containing sodium persulfate and sulfuric acid, removing a surface oxide layer, increasing the surface roughness and improving the adhesive force of a subsequent mask, washing the heat dissipation plate by using deionized water again after the treatment is completed, and carrying out drying treatment. Based on the chemical etching principle, by precisely regulating and controlling parameters such as the concentration, the temperature and the time of the etching liquid and combining the high-precision pattern transfer capacity of the photoetching mask technology, precise control over etching of the two faces at different depths can be achieved, the depth error can be controlled within + / -0.02 mm to + / -0.03 mm, and the pattern alignment precision reaches + / -0.04 mm to + / -0.05 mm.

Description

Technical Field

[0001] The invention belongs to the technical field of heat sink etching, and in particular relates to a heat sink double-sided different-depth etching process. Background Art

[0002] The most common heat sink etching process relies on immersion etching, which involves completely immersing the heat sink in an etchant. This process has significant drawbacks. Firstly, the etchant is unevenly distributed across the heat sink surface, resulting in inconsistent etching depth and effect, making it difficult to meet the high-precision requirements of double-sided, variable-depth etching. Secondly, when fully immersed, the etchant concentration must be reduced to prevent defects in other areas. This results in a slow reaction between the heat sink and the etchant during the etching process, resulting in low production efficiency and an inability to meet the needs of large-scale production. Summary of the Invention

[0003] The purpose of the present invention is to provide a double-sided differential depth etching process for a heat sink. In view of the problems of uneven etching liquid distribution, poor consistency in etching depth and effect, and inability to meet the high-precision requirements of double-sided differential depth etching in the existing heat sink etching process by immersion etching, the present invention aims to achieve uniform distribution of etching liquid on the surface of the heat sink through an innovative single-sided spray etching method, combined with high-precision mask production technology and precise etching parameter control, thereby ensuring high precision and consistency of double-sided differential depth etching and meeting the high-precision requirements of modern electronic equipment for complex and diversified designs of heat sinks.

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

[0005] A heat dissipation plate double-sided different-depth etching process includes the following steps:

[0006] Step 1: Pre-treatment

[0007] a) Cleaning: Place the heat sink in an alkaline detergent at 50-60°C for 10-15 minutes to remove oil, dust and other impurities on the surface, then rinse with deionized water several times to ensure that the surface is clean and free of residue;

[0008] b) Micro-etching: Use a micro-etching solution containing sodium persulfate and sulfuric acid to micro-etch the surface of the heat sink for 3-5 minutes to remove the surface oxide layer, increase the surface roughness, and improve the adhesion of the subsequent mask. After the treatment is completed, rinse it again with deionized water and dry it;

[0009] Step 2: Mask preparation

[0010] c) Single-sided mask: Using photolithography technology, photoresist is coated on one side of the heat sink. Through exposure, development and other processes, the designed mask pattern is transferred to the photoresist to form a single-sided mask;

[0011] d) Masking the other side: After the mask on one side is cured, the heat sink is flipped over and the above photolithography process is repeated on the other side to make a mask on the other side;

[0012] Step 3: Double-sided deep etching

[0013] e) First etching: Place the heat sink with double-sided mask in an etching machine equipped with a single-sided spray system, start the etcher, adjust the etching solution spray pressure to 0.3-0.5 MPa, and spray the etching solution in a uniform mist on the side that needs to be deeply etched. The etching solution concentration is controlled at 15-20%, and the etching time is 15-20 minutes;

[0014] f) Secondary etching: After the first etching is completed, remove the heat sink and inspect and repair the mask. Place the heat sink back into the etching machine and adjust the spray direction to the other side (i.e., the side that needs shallower etching). At the same time, reduce the etching solution spray pressure to 0.2-0.3MPa, adjust the etching solution concentration to 8-12%, and the etching time to 8-12 minutes. Similarly, use the rotating device to slowly rotate the heat sink to complete the secondary etching, achieving etching effects of different depths on both sides.

[0015] Step 4: Post-processing

[0016] g) De-filming: Place the etched heat sink in a de-filming solution containing sodium hydroxide at a temperature of 50-60°C for 5-10 minutes to remove the photoresist mask on the surface. After de-filming, rinse with deionized water.

[0017] h) Cleaning and drying: Clean the heat sink for the final time to remove the etching solution and film stripping solution remaining on the surface, then use hot air drying at a temperature of 80-100°C for 10-15 minutes to completely dry the surface of the heat sink.

[0018] Furthermore, in the step three: double-sided different-depth etching, the spray pressure, etching solution concentration and etching time can be adjusted according to different etching depth requirements.

[0019] Furthermore, the cleaning equipment is an ultrasonic cleaning machine, which has a high-efficiency cleaning ability and can completely remove impurities on the surface of the heat sink. The capacity of the cleaning tank is selected according to the production scale.

[0020] The technical effects achieved by the present invention are:

[0021] 1. Based on the principle of chemical etching, this invention precisely controls parameters such as etching solution concentration, temperature, and time, and combines the high-precision pattern transfer capabilities of photolithography mask technology to achieve precise control of double-sided etching at different depths. The depth error can be controlled within ±0.02mm-±0.03mm, and the pattern alignment accuracy reaches ±0.04mm-±0.05mm. This meets the complex and diverse design requirements of heat sinks in modern electronic devices and provides a strong guarantee for the realization of high-performance heat dissipation structures.

[0022] 2. The single-sided spraying technology of the present invention, combined with the rotation of the heat sink, allows the etching liquid to evenly cover the etching surface, significantly shortening the etching time and improving the etching efficiency. Furthermore, different depths of etching can be achieved by mixing different concentrations. Compared with the traditional immersion etching process, it can better achieve different depth effects and improve production efficiency by 30%-50%. At the same time, the application of continuous etching machines and automated process flows reduces manual intervention and labor costs. Precise process control reduces scrap rates, further reduces production costs, and improves the economic benefits of the enterprise.

[0023] 3. The strict pre-treatment process of the present invention effectively removes impurities and oxide layers on the surface of the heat sink; micro-etching increases surface roughness, enhances photoresist adhesion, and ensures mask stability; the single-sided spray method and heat sink rotation ensure uniform etching and reduce surface defects; the perfect post-treatment process thoroughly removes residual substances, making the surface of the heat sink smooth after etching, and the surface roughness is controlled within the ideal range. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic flow diagram of the present invention. DETAILED DESCRIPTION

[0025] 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.

[0026] 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.

[0027] Example 1:

[0028] See also Figure 1 As shown, the present invention provides a heat dissipation plate double-sided different depth etching process, comprising the following steps:

[0029] Step 1: Pre-treatment

[0030] a) Cleaning: Soak the aluminum alloy heat sink in an alkaline detergent (5% concentration) in a 55°C constant temperature water bath for 12 minutes. After soaking, remove the heat sink and place it in a deionized water bath. Rinse three times in a 3-minute rinse cycle to ensure that all surface impurities, such as oil and dust, are completely removed.

[0031] b) Microetching: Prepare a microetching solution containing sodium persulfate (10% by mass) and sulfuric acid (5% by mass), place the heat sink in the microetching solution, and treat it at 32°C for 4 minutes. After the microetching is completed, quickly rinse the heat sink surface with deionized water to remove the residual microetching solution, and then place it in a hot air drying oven and dry it at 80°C for 8 minutes.

[0032] Step 2: Mask preparation

[0033] c) Single-sided mask: A layer of positive photoresist is evenly coated on the A side of the heat sink. The thickness of the photoresist is uniformed by a spin coater. The heat sink coated with photoresist is placed in a photolithography machine and exposed to ultraviolet light for 15 seconds. After exposure, the heat sink is placed in a sodium carbonate solution (concentration of 2.5%) and developed for 1.5 minutes. After development, it is rinsed with deionized water and then baked in an oven at 120°C for 15 minutes to cure the photoresist to form the A side mask.

[0034] d) Mask on the other side: Flip the heat sink over and repeat the above steps of coating, exposing, developing, and baking to make a mask on side B.

[0035] Step 3: Double-sided deep etching

[0036] e) First etching: Place the heat sink with the double-sided mask in a continuous etcher equipped with a single-sided spray system. Adjust the spray pressure of the etching solution (ingredients: ferric chloride, concentration 18%) to 0.4 MPa so that the etching solution is evenly sprayed on the A side in a mist form. Set the etcher temperature to 48°C, start the etcher, and turn on the rotating device at the same time to rotate the heat sink at 8 rpm. The etching time is controlled to 18 minutes. The etching solution concentration and temperature are monitored in real time during the etching process to ensure parameter stability.

[0037] f) Secondary etching: After the etching of side A is completed, take out the heat sink, carefully check the masks on both sides A and B, repair any damaged or defective parts, put the heat sink into the etcher again, adjust the spray direction to side B, reduce the etching solution (concentration adjusted to 10%) spray pressure to 0.25MPa, set the temperature to 42°C, start the etcher, the heat sink still rotates at a speed of 8 rpm, the etching time is 10 minutes, complete the B side etching, and achieve etching effects of different depths on both sides.

[0038] Step 4: Post-processing

[0039] g) Stripping: Put the etched heat sink into the stripping solution containing sodium hydroxide (concentration of 10%) and immerse it in the solution at 55°C for 8 minutes to remove the surface photoresist mask. After stripping is completed, rinse the heat sink with deionized water repeatedly to ensure that the stripping solution is completely removed;

[0040] h) Cleaning and drying: Put the heat sink into an ultrasonic cleaner and clean it with deionized water for 5 minutes to further remove the surface impurities. After cleaning, put it into a hot air circulating drying oven and dry it at 90°C for 12 minutes to completely dry the surface of the heat sink.

[0041] In this embodiment, in the step three: double-sided different etching, the spray pressure, etching solution concentration and etching time can be adjusted according to different etching depth requirements.

[0042] In this embodiment, the cleaning equipment is an ultrasonic cleaner, which has high cleaning capacity and can completely remove the impurities on the surface of the heat sink. The cleaning tank capacity is selected according to the production scale.

[0043] Example Two:

[0044] Step One: Pretreatment

[0045] a) Cleaning: Put the copper alloy heat sink into the prepared alkaline cleaning agent (concentration of 6%) solution tank and immerse it in the constant temperature water bath pot with a temperature setting of 58°C for 13 minutes. After immersion, take out the heat sink with a clamp and quickly put it into the deionized water cleaning tank for four times of rinsing, each time for 3.5 minutes, to completely remove the surface oil, dust and other impurities. After rinsing, place it on a clean tray.

[0046] b) Micro-etching: Prepare a micro-etching solution composed of ammonium persulfate (mass fraction of 12%) and sulfuric acid (mass fraction of 6%), pour it into a special treatment tank and adjust the temperature to 33°C. Then immerse the cleaned heat sink in the micro-etching solution for 4.5 minutes, continuously observe the reaction condition during the process. After micro-etching is completed, immediately rinse the heat sink with a large amount of deionized water to remove the residual micro-etching solution, and then put it into a hot air drying oven preheated to 85°C for drying for 9 minutes. After drying is completed, carefully check the micro-etching effect on the surface of the heat sink. If it is not ideal, reprocess it in time.

[0047] Step Two: Mask Making

[0048] c) Single-Sided Masking: A layer of positive photoresist is evenly applied to the C-side of the heat sink using a dedicated coating device. A spin coater is used to evenly distribute the photoresist. The coated heat sink is placed in a photolithography machine and exposed to UV light for 18 seconds. After exposure, the heat sink is developed in a 2.8% sodium carbonate solution for 1.8 minutes. After development, it is rinsed with deionized water and baked in a 125°C oven for 18 minutes to cure the photoresist, forming the C-side mask.

[0049] d) Mask on the other side: Flip the heat sink with the C-side mask and repeat the steps of coating, exposing, developing, and baking to make the D-side mask.

[0050] Step 3: Double-sided deep etching

[0051] e) First etching: Place the heat sink with double-sided mask steadily into a continuous etcher equipped with a single-sided spray system, ensuring that the C side faces upwards and directly toward the spray head. Adjust the spray pressure of the etching solution (concentration 22%) to 0.5 MPa through the equipment control panel, set the etcher temperature to 52°C, start the rotating device to rotate the heat sink, start the etching program, and control the etching time to 22 minutes. During the etching process, arrange a dedicated person to record the etching solution concentration and temperature every 4 minutes. If any parameter deviation is found, adjust it immediately.

[0052] f) Secondary etching: After the etching of the C side is completed, turn off the etcher. After the equipment stops running, remove the heat sink and carefully inspect the C and D masks. If there are any damage or defects, repair them with a special repair tool. Then, put the heat sink back into the etcher, adjust the spray direction to the D side, reduce the etching solution (adjust the concentration to 12%), reduce the spray pressure to 0.28MPa, and set the temperature to 43°C. Start the etcher and etch for 12 minutes to complete the D side etching, achieving an etching effect of different depths on both sides.

[0053] Step 4: Post-processing

[0054] g) De-filming: Place the etched heat sink in a stripping solution tank containing sodium hydroxide (12%) and soak at 58°C for 9 minutes to remove the photoresist mask on the surface. Stir the stripping solution appropriately during soaking to speed up the stripping process. After stripping, rinse the heat sink repeatedly with deionized water to ensure that the stripping solution is completely removed. After rinsing, visually inspect and remove any remaining photoresist.

[0055] h) Cleaning and Drying: After de-filming, place the heat sink in an ultrasonic cleaner and rinse with sufficient deionized water for 6 minutes to further remove any surface impurities. After cleaning, remove the heat sink using a fixture and place it in a hot air circulation drying oven preheated to 95°C for 15 minutes to thoroughly dry the heat sink surface. After drying, allow the heat sink to cool to room temperature before removing it for testing.

[0056] In this embodiment, in step three: double-sided different-depth etching, the spray pressure, etching solution concentration and etching time can be adjusted according to different etching depth requirements.

[0057] In this embodiment, the cleaning equipment is an ultrasonic cleaning machine, which has a high-efficiency cleaning ability and can completely remove impurities on the surface of the heat sink. The capacity of the cleaning tank is selected according to the production scale.

[0058] The present invention is based on the principle of chemical etching. By precisely controlling parameters such as etching solution concentration, temperature and time, combined with the high-precision pattern transfer capability of photolithography mask technology, it is possible to achieve precise control of double-sided etching at different depths. The depth error can be controlled within ±0.02mm-±0.03mm, and the pattern alignment accuracy reaches ±0.04mm-±0.05mm, meeting the complex and diverse design requirements of heat sinks for modern electronic equipment and providing a strong guarantee for the realization of high-performance heat dissipation structures. The single-sided spraying technology of the present invention is combined with the rotation of the heat sink to make the etching liquid evenly cover the etching surface, greatly shorten the etching time, improve the etching efficiency, and achieve etching effects of different depths by matching different concentrations. Compared with the traditional immersion etching process, it can achieve better depth effect and improve production efficiency by 30%-50%. At the same time, the application of continuous etching machine and automated process flow reduces manual intervention and labor costs; precise process control reduces scrap rate, further reduces production costs and improves enterprise economic benefits; the strict pre-treatment process of the present invention effectively removes impurities and oxide layer on the surface of the heat sink, micro-etching increases surface roughness, enhances photoresist adhesion, and ensures mask stability; single-sided spraying method and heat sink rotation ensure uniform etching and reduce surface defects; perfect post-processing process thoroughly removes residual substances, making the surface of the heat sink smooth after etching, and the surface roughness is controlled within the ideal range

[0059] 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 heat sink double-sided deep etching process, characterized in that; The steps include: Step 1: Pre-treatment a) Cleaning: Place the heat sink in an alkaline detergent at 50-60°C for 10-15 minutes to remove oil, dust and other impurities on the surface, then rinse with deionized water several times to ensure that the surface is clean and free of residue; b) Micro-etching: Use a micro-etching solution containing sodium persulfate and sulfuric acid to micro-etch the surface of the heat sink for 3-5 minutes to remove the surface oxide layer, increase the surface roughness, and improve the adhesion of the subsequent mask. After the treatment is completed, rinse it again with deionized water and dry it; Step 2: Mask preparation c) Single-sided mask: Using photolithography technology, photoresist is coated on one side of the heat sink. Through exposure, development and other processes, the designed mask pattern is transferred to the photoresist to form a single-sided mask; d) Masking the other side: After the mask on one side is cured, the heat sink is flipped over and the above photolithography process is repeated on the other side to make a mask on the other side; Step 3: Double-sided deep etching e) First etching: Place the heat sink with the double-sided mask in an etching machine equipped with a single-sided spray system, turn on the etcher, adjust the etching solution spray pressure to 0.3-0.5 MPa, and spray the etching solution in a uniform mist on the side that needs to be deeply etched. The etching solution concentration is controlled at 15-20%, and the etching time is 15-20 minutes; f) Secondary etching: After the first etching is completed, remove the heat sink and inspect and repair the mask. Place the heat sink back into the etching machine and adjust the spray direction to the other side (i.e., the side that needs shallower etching). At the same time, reduce the etching solution spray pressure to 0.2-0.3MPa, adjust the etching solution concentration to 8-12%, and the etching time to 8-12 minutes. Similarly, use the rotating device to slowly rotate the heat sink to complete the secondary etching, achieving etching effects of different depths on both sides. Step 4: Post-processing g) De-filming: Place the etched heat sink in a de-filming solution containing sodium hydroxide at a temperature of 50-60°C for 5-10 minutes to remove the photoresist mask on the surface. After de-filming, rinse with deionized water. h) Cleaning and drying: Clean the heat sink for the final time to remove the etching solution and film stripping solution remaining on the surface, then use hot air drying at a temperature of 80-100°C for 10-15 minutes to completely dry the surface of the heat sink.

2. The heat dissipation plate double-sided different-depth etching process according to claim 1, characterized in that: In the step 3: double-sided different-depth etching, the spray pressure, etching solution concentration and etching time can be adjusted according to different etching depth requirements.

3. The heat dissipation plate double-sided different-depth etching process according to claim 1, characterized in that: The cleaning equipment is an ultrasonic cleaning machine with high efficiency cleaning ability, which can completely remove impurities on the surface of the heat sink. The capacity of the cleaning tank is selected according to the production scale.

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