Method for removing aluminum on surface of steel mold

Abstract

The invention provides a method for removing aluminum on the surface of a steel mold, which comprises the following steps: carrying out first washing on a to-be-treated steel mold by using a phosphoric acid-containing solution to obtain a first steel mold; the first steel mold is placed in an alkaline solution and synchronously subjected to ultrasonic soaking and cleaning, and a second steel mold is obtained; and the second steel mold is subjected to second washing, and the steel mold with aluminum removed is obtained. According to the method for removing the aluminum on the surface of the steel mold, the aluminum can be completely and effectively removed on the basis that the steel mold is not damaged, the production quality is improved, and the application prospect is wide.

Description

Technical Field

[0001] The invention relates to the field of separation technology, in particular to a method for removing aluminum from the surface of a steel mold. Background Art

[0002] Vacuum evaporation and sputtering are the two most popular PVD coating methods. Vacuum evaporation involves heating an evaporating material under vacuum conditions, causing it to deposit onto the substrate surface as a thin film. Vacuum evaporation offers simplicity, ease of operation, and rapid film formation. It is widely used in optical components, LEDs, flat panel displays, and discrete semiconductors. From a manufacturing perspective, the manufacturing complexity of evaporation materials is far lower than that of sputtering targets, making it a common method for coating small substrates.

[0003] Evaporation material is the main raw material for wafer back-gold technology. The semiconductor industry has the highest requirements for the purity and surface quality of evaporation material. The higher the purity of the evaporation material, the denser the surface oxide film, the stronger the bond with the internal atoms, and the better the corrosion resistance to certain acids, alkalis, seawater, sewage and sulfur-containing air.

[0004] CN108754183B discloses a preparation method and titanium evaporation material, which comprises the following steps: (a) pre-treating raw titanium; (b) ultrasonically oscillating the pre-treated titanium in cleaning oil for 10-20 minutes; then ultrasonically oscillating it in a steam drying system for 5-15 minutes; then acid washing it for 3-6 minutes; then ultrasonically oscillating it in water for 5-10 minutes; and then drying it; (c) placing the titanium obtained in step (b) in a centrifugal grinder, adding a detergent and water, and centrifugally grinding it; the amount of the detergent used is 30-50 mL, the grinding speed is 180-200 r / min, and the grinding time is 10-20 minutes; and (d) post-treating the titanium obtained in step (c) to obtain the titanium evaporation material.

[0005] CN108987273A discloses a surface treatment method for a silver evaporation material, comprising: providing a silver evaporation material; performing a centrifugal grinding operation on the silver evaporation material; after the centrifugal grinding operation, performing a cleaning operation on the silver evaporation material; and after the cleaning operation, performing a drying process on the silver evaporation material.

[0006] However, none of the above technologies realizes that the evaporation material may cause Al residue on the mold surface during the previous extrusion process. However, the Al residue on the mold surface may affect the quality and purity of the processed product.

[0007] Therefore, it is urgent to develop a method for removing Al from the mold surface. Summary of the Invention

[0008] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for removing aluminum from the surface of a steel mold, which can quickly remove the aluminum adhered to the surface of the steel mold without damaging the surface of the steel mold and has broad application prospects.

[0009] To achieve this object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a method for removing aluminum from the surface of a steel mold, the method comprising: subjecting the steel mold to be treated to a first rinse with a phosphoric acid solution to obtain a first steel mold; placing the first steel mold in an alkaline solution and simultaneously performing ultrasonic immersion cleaning to obtain a second steel mold; and subjecting the second steel mold to a second rinse to obtain a steel mold after the aluminum has been removed.

[0011] The aluminum remaining on the surface of the steel mold to be treated in the present invention is not simply bonded, but rather remains from the evaporation process in the previous extrusion process. This aluminum forms a tight bond with the steel mold surface, and a dense oxide film forms on the aluminum surface. This dense oxide film further enhances the bonding between the aluminum and the steel mold, thereby increasing the difficulty of removing the aluminum from the steel mold surface. To address this issue, the present invention first uses a phosphoric acid solution to break down the surface oxide film on the aluminum, but a rinsing step is required, which is short and does not damage the steel mold surface. Subsequently, the first steel mold is immersed in a low-concentration alkaline solution for cleaning, which neither damages the steel mold nor completely removes the aluminum, thus avoiding any subsequent negative impact on the chip.

[0012] Preferably, the material of the steel mold to be processed is H13.

[0013] Preferably, aluminum and / or aluminum oxide adhere to the surface of the steel mold to be treated.

[0014] Preferably, the concentration of the phosphoric acid solution is 5 to 15 wt%, for example, 5 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt% or 15 wt%, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0015] In the present invention, the concentration of the phosphoric acid solution is preferably controlled within the above range, which can ensure the removal of the aluminum oxide film while avoiding damage to the steel mold.

[0016] Preferably, the first flushing time is 10 to 20 seconds, for example, it can be 10 seconds, 12 seconds, 13 seconds, 14 seconds, 15 seconds, 16 seconds, 17 seconds, 18 seconds, 19 seconds or 20 seconds, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0017] The present invention requires strict control of the time of the first flushing to avoid damage to the steel mold.

[0018] Preferably, the temperature of the first flushing is 15-40°C, for example, it can be 15°C, 18°C, 21°C, 24°C, 27°C, 29°C, 32°C, 35°C, 38°C or 40°C, but is not limited to the listed values. Other values ​​not listed within this range are also applicable.

[0019] Preferably, the concentration of the alkaline solution is 1 to 5 wt%, for example, it can be 1 wt%, 1.5 wt%, 1.9 wt%, 2.4 wt%, 2.8 wt%, 3.3 wt%, 3.7 wt%, 4.2 wt%, 4.6 wt% or 5 wt%, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0020] The present invention preferably controls the concentration of the alkaline solution within a reasonable range, which can better improve the cleaning effect of the steel mold and avoid damage to the steel mold.

[0021] Preferably, the alkali in the alkali solution comprises sodium hydroxide and / or potassium hydroxide.

[0022] Preferably, the temperature of the ultrasonic immersion cleaning is 75-85°C, for example, it can be 75°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C or 85°C, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0023] Preferably, the power of the ultrasonic immersion cleaning is 150 to 300 W, for example, it can be 150 W, 167 W, 184 W, 200 W, 217 W, 234 W, 250 W, 267 W, 284 W or 300 W, but is not limited to the listed values. Other values ​​not listed within this range are also applicable.

[0024] Preferably, the duration of the ultrasonic immersion cleaning is 20 to 28 hours, for example, it can be 20 hours, 20.9 hours, 21.8 hours, 22.7 hours, 23.6 hours, 24.5 hours, 25.4 hours, 26.3 hours, 27.2 hours or 28 hours, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0025] Preferably, the phosphoric acid solution further contains polyvinyl alcohol.

[0026] The second core invention of the present invention is to add polyvinyl alcohol to the phosphoric acid solution. Polyvinyl alcohol tends to adsorb on the surface of the steel mold rather than adhere to the aluminum surface. Therefore, when the phosphoric acid solution is used for the first rinse, the addition of polyvinyl alcohol can better protect the surface of the steel mold and extend the second rinse time of the phosphoric acid solution, thereby improving the aluminum removal effect.

[0027] Preferably, the concentration of polyvinyl alcohol in the phosphoric acid solution is 1 to 3 wt%, for example, 1 wt%, 1.3 wt%, 1.5 wt%, 1.7 wt%, 1.9 wt%, 2.2 wt%, 2.4 wt%, 2.6 wt%, 2.8 wt% or 3 wt%, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0028] Preferably, the flushing liquid of the second flushing is water.

[0029] Preferably, the second flushing time is 10 to 20 minutes, for example, it can be 10 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes or 20 minutes, but is not limited to the listed values. Other values ​​not listed within this range are also applicable.

[0030] Preferably, the method comprises:

[0031] The steel mold to be treated, with aluminum and / or aluminum oxide adhered to the surface, is first rinsed with a phosphoric acid solution containing 5-15wt% phosphoric acid and 1-3wt% polyvinyl alcohol at 15-40° C. for 10-20 seconds to obtain a first steel mold.

[0032] The first steel mold is then placed in a 1-5wt% alkaline solution and simultaneously subjected to ultrasonic immersion cleaning at 75-85°C and 150-300W for 20-28 hours to obtain a second steel mold.

[0033] The second steel mold is rinsed with water for a second time for 10 to 20 minutes to obtain a steel mold after aluminum is removed.

[0034] Compared with the prior art, the present invention has at least the following beneficial effects:

[0035] (1) The method for removing aluminum from the surface of a steel mold provided by the present invention can effectively remove aluminum and / or aluminum oxide from the surface of the steel mold without damaging the surface of the steel mold, thereby avoiding the problem of impurities remaining in the steel mold causing a decrease in chip yield;

[0036] (2) After treatment, the defect rate of the steel mold surface provided by the present invention is within 0.1%, the surface flatness is within 0.5 μm, the residual aluminum content on the surface is within 50 ppm, and the aluminum removal effect is excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the steel mold to be processed in Example 1 of the present invention.

[0038] Figure 2 Schematic diagram of the steel mold after cleaning in Example 1 of the present invention.

[0039] In the figure: 1. Steel mold layer; 2. Aluminum and aluminum oxide layer. DETAILED DESCRIPTION

[0040] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0041] It should be understood that, in the description of the present invention, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0042] Example 1

[0043] This embodiment provides a method for removing aluminum from the surface of a steel mold, the method comprising:

[0044] The steel mold to be treated (H13) with aluminum and aluminum oxide on the surface (see Figure 1 The steel mold to be treated includes a steel mold layer 1 and an aluminum and aluminum oxide layer 2 adhered to the surface of the steel mold layer) using a phosphoric acid solution with a phosphoric acid concentration of 10wt% and a polyvinyl alcohol (10000) concentration of 2wt% for a first rinse at 20°C for 15s to obtain a first steel mold.

[0045] The first steel mold is then placed in a 2.5 wt % sodium hydroxide solution and simultaneously subjected to 80° C., 180 W ultrasonic immersion cleaning for 24 hours to obtain a second steel mold.

[0046] The second steel mold was rinsed with water for 15 minutes to obtain a steel mold after aluminum removal (see Figure 2 ).

[0047] Example 2

[0048] This embodiment provides a method for removing aluminum from the surface of a steel mold, the method comprising:

[0049] The steel mold (H13) to be treated with aluminum and aluminum oxide on its surface was rinsed for 20 seconds at 15° C. using a phosphoric acid solution containing 15 wt% phosphoric acid and 3 wt% polyvinyl alcohol (10000) to obtain a first steel mold.

[0050] The first steel mold was then placed in a 1 wt % potassium hydroxide solution and simultaneously subjected to ultrasonic immersion cleaning at 75° C. and 150 W for 28 hours to obtain a second steel mold.

[0051] The second steel mold is rinsed with water for a second time for 10 minutes to obtain a steel mold after aluminum is removed.

[0052] Example 3

[0053] This embodiment provides a method for removing aluminum from the surface of a steel mold, the method comprising:

[0054] The steel mold (H13) to be treated with aluminum and aluminum oxide on its surface was rinsed for 10 seconds at 40° C. using a phosphoric acid solution containing 5 wt% phosphoric acid and 1 wt% polyvinyl alcohol (10000) to obtain a first steel mold.

[0055] The first steel mold is then placed in a 5 wt % sodium hydroxide solution and simultaneously subjected to ultrasonic immersion cleaning at 85° C. and 300 W for 20 hours to obtain a second steel mold.

[0056] The second steel mold is rinsed with water for a second time for 20 minutes to obtain a steel mold after aluminum is removed.

[0057] Example 4

[0058] This embodiment provides a method for removing aluminum from the surface of a steel mold. The method is the same as that of Example 1 except that the concentration of polyvinyl alcohol (10000) is 0.5 wt %, and thus will not be described in detail here.

[0059] Example 5

[0060] This embodiment provides a method for removing aluminum from the surface of a steel mold. The method is the same as that of Example 1 except that the concentration of polyvinyl alcohol (10000) is 3.5 wt %, and thus will not be described in detail here.

[0061] Example 6

[0062] This embodiment provides a method for removing aluminum from the surface of a steel mold. The method is the same as that of Example 1 except that the concentration of phosphoric acid is 20 wt %, and details thereof will not be repeated here.

[0063] Example 7

[0064] This embodiment provides a method for removing aluminum from the surface of a steel mold. The method is the same as that of Example 1 except that the phosphoric acid concentration is 1 wt %, and details thereof will not be repeated here.

[0065] Example 8

[0066] This embodiment provides a method for removing aluminum from the surface of a steel mold. Except that the duration of the first flushing is 25 seconds, the rest of the method is the same as that of Example 1, and will not be repeated here.

[0067] Example 9

[0068] This embodiment provides a method for removing aluminum from the surface of a steel mold. The method is the same as that of Example 1 except that the temperature for ultrasonic immersion cleaning is 60° C., and thus will not be described in detail here.

[0069] Example 10

[0070] This embodiment provides a method for removing aluminum from the surface of a steel mold. The method is the same as that of Example 1 except that the temperature for ultrasonic immersion cleaning is 90° C., and details thereof will not be repeated here.

[0071] Example 11

[0072] This embodiment provides a method for removing aluminum from the surface of a steel mold. The method is the same as that of Example 1 except that polyvinyl alcohol is not added, and will not be described in detail here.

[0073] Example 12

[0074] This embodiment provides a method for removing aluminum from the surface of a steel mold. The method is the same as that of Example 1 except that polyvinyl alcohol is replaced by ethanol, and thus will not be described in detail here.

[0075] Comparative Example 1

[0076] This comparative example provides a method for removing aluminum from the surface of a steel mold. The method is the same as Example 1 except that phosphoric acid is replaced by oxalic acid of equal concentration, and the details will not be repeated here.

[0077] Comparative Example 2

[0078] This comparative example provides a method for removing aluminum from the surface of a steel mold. The method is the same as Example 1 except that phosphoric acid is replaced by acetic acid of equal concentration, and the rest is not repeated here.

[0079] Comparative Example 3

[0080] This comparative example provides a method for removing aluminum from the surface of a steel mold. Except for not performing the first flushing, the method is the same as Example 1 and will not be described in detail here.

[0081] Comparative Example 4

[0082] This comparative example provides a method for removing aluminum from the surface of a steel mold. The method is the same as Example 1 except that ultrasonic treatment is not performed and only sodium hydroxide solution immersion cleaning is performed. The details will not be repeated here.

[0083] Test method: SEM-EDS surface scanning was used to analyze the aluminum content on the surface of the steel mold, and an ultrasonic flaw detector was used to evaluate the surface defect rate of the cleaned steel mold.

[0084] The test results of the above embodiments and comparative examples are shown in Table 1.

[0085] Table 1

[0086]

[0087]

[0088] From Table 1 we can see the following points:

[0089] (1) It can be seen from Examples 1 to 3 that the method for removing aluminum from the surface of a steel mold provided by the present invention has the effect of efficiently removing aluminum from the surface of a steel mold, wherein the residual aluminum content after cleaning is within 40 ppm, the surface defect rate of the steel mold after cleaning is within 0.1%, and the flatness of the steel mold after cleaning is within 0.5 μm.

[0090] (2) From the combination of Example 1 and Examples 4 to 5, it can be seen that in Example 1, the concentration of polyvinyl alcohol is 2 wt%, compared with the concentrations of polyvinyl alcohol in Examples 4 to 5 being 0.5 wt% and 3.5 wt% respectively, the residual amount of aluminum after cleaning in Example 1 is 40 ppm, the surface defect rate of the steel mold after cleaning is only 0.08%, and the flatness of the steel mold after cleaning is only 0.3 μm, while the surface defect rate of the steel mold after cleaning in Example 4 is as high as 0.15%, and the flatness is 0.7 μm. The residual amount of aluminum in Example 5 is above 65 ppm. This shows that the present invention can further improve the aluminum removal effect on the surface of the steel mold by preferably using a specific concentration of polyvinyl alcohol.

[0091] (3) It can be seen from Example 1 and Examples 6 to 8 that the concentration of the phosphoric acid solution in the first rinse and the rinse time are critical for removing aluminum from the steel mold surface. The present invention preferably controls the concentration of the phosphoric acid solution and the rinse time within a reasonable range, which can better improve the removal effect of aluminum from the steel mold surface.

[0092] (4) It can be seen from Example 1, Examples 9 to 10, and Comparative Example 4 that the specific selection of the ultrasonic process and the immersion temperature during ultrasonic immersion cleaning can significantly improve the removal effect on the surface of the steel mold.

[0093] (5) It can be seen from Example 1, Examples 11 to 12, and Comparative Examples 1 to 3 that the first flush is critical for the removal of aluminum. The present invention uses a specific acid and polyvinyl alcohol as protective agents and adopts the first flushing method to achieve efficient removal of aluminum without damaging the surface of the steel mold.

[0094] The present invention uses the above-described embodiments to illustrate the detailed features of the present invention. However, the present invention is not limited to the above-described detailed features, which does not mean that the present invention must rely on the above-described detailed features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for the selected technical features of the present invention, additions to auxiliary technical features, and selections of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for removing aluminum from the surface of a steel mold, characterized in that: The method comprises: The steel mold to be treated is first rinsed with a phosphoric acid solution to obtain a first steel mold; The first steel mold is then placed in an alkaline solution and simultaneously subjected to ultrasonic immersion cleaning to obtain a second steel mold; The second steel mold is subjected to a second flushing to obtain a steel mold after aluminum is removed.

2. The method according to claim 1, characterized in that The material of the steel mold to be processed is H13; Preferably, aluminum and / or aluminum oxide adhere to the surface of the steel mold to be treated.

3. The method according to claim 1 or 2, characterized in that: The concentration of the phosphoric acid solution is 5 to 15 wt %.

4. The method according to any one of claims 1 to 3, characterized in that: The first flushing time is 10 to 20 seconds; Preferably, the temperature of the first flushing is 15-40°C.

5. The method according to any one of claims 1 to 4, characterized in that: The concentration of the alkaline solution is 1 to 5 wt%; Preferably, the alkali in the alkali solution comprises sodium hydroxide and / or potassium hydroxide.

6. The method according to any one of claims 1 to 5, characterized in that: The temperature of the ultrasonic immersion cleaning is 75-85°C; Preferably, the power of the ultrasonic immersion cleaning is 150 to 300 W; Preferably, the ultrasonic immersion cleaning lasts for 20 to 28 hours.

7. The method according to claim 6, characterized in that The phosphoric acid solution also contains polyvinyl alcohol.

8. The method according to any one of claims 1 to 7, characterized in that: The concentration of polyvinyl alcohol in the phosphoric acid solution is 1-3 wt %.

9. The method according to any one of claims 1 to 8, characterized in that: The second flushing liquid is water; Preferably, the second flushing time is 10 to 20 minutes.

10. The method according to any one of claims 1 to 9, characterized in that: The method comprises: The steel mold to be treated, the surface of which is adhered with aluminum and / or aluminum oxide, is first rinsed with a phosphoric acid solution having a phosphoric acid concentration of 5 to 15 wt% and a polyvinyl alcohol concentration of 1 to 3 wt% at 15 to 40° C. for 10 to 20 seconds to obtain a first steel mold; The first steel mold is then placed in a 1-5wt% alkaline solution and simultaneously subjected to ultrasonic immersion cleaning at 75-85°C and 150-300W for 20-28 hours to obtain a second steel mold; The second steel mold is rinsed with water for a second time for 10 to 20 minutes to obtain a steel mold after aluminum is removed.

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