A high-precision low-expansion alloy foil high-surface quality control method for metal mask plates

Abstract

Provided is a high-precision metal mask plate low-expansion alloy foil high-surface quality control method, comprising: sequentially performing hot rolling, pickling to remove the oxide skin, first grinding treatment, first cold rolling treatment, second grinding treatment, and second cold rolling treatment on the alloy foil blank. In the first grinding treatment and the second grinding treatment, the grinding wheel rotates along its own axial direction and performs periodic reciprocating motion along the width direction of the plate / band, and the axial direction of the grinding wheel is perpendicular to the surface of the plate / band. In the second cold rolling treatment, the work roll is subjected to the work roll grinding treatment method for grinding treatment, and the polishing roll is first subjected to the work roll grinding treatment method for grinding treatment and then subjected to the polishing roll polishing treatment method for polishing treatment. Through the method, a high-precision metal mask plate low-expansion alloy foil with a thickness of not greater than 0.04 mm and a horizontal / vertical roughness difference rate of ≤25% is obtained, meeting the high-surface quality requirements of the OLED industry.

Description

Technical Field

[0001] This invention relates to a method for controlling the high surface quality of low-expansion alloy foil for high-precision metal photomasks, and more specifically to a method for controlling the high surface quality of low-expansion alloy foil for metal photomasks that is not prone to deformation or warping, has high flatness, high strength, high alignment accuracy on the frame, and good etchability. Background Technology

[0002] Compared to traditional screens, OLED screens offer higher contrast, more vibrant colors, and wider viewing angles because each pixel emits its own light. They also boast advantages such as ultra-thin, flexible designs and portability. Therefore, OLED technology has become the dominant technology for panels in recent years. Currently, the main method for mass production of OLED panels is vacuum evaporation, which requires high-precision metal mask deposition technology. With technological advancements and societal progress, people's demands for all aspects of life are increasing, especially for high-quality images. This necessitates higher pixel quality in electronic products. However, this pixel quality largely depends on the precision of the metal mask, and the surface quality of the foil is one of the main factors affecting the precision of the metal mask.

[0003] Therefore, controlling the surface quality of the foil used for metal photomasks is crucial.

[0004] Low-expansion alloys, due to their approximately constant dimensions within a certain temperature range, are widely used in the fabrication of metal photomasks. As the requirements for metal photomasks increase, the requirements for the materials used in their fabrication also increase accordingly, namely, a sheet thickness ≤0.04μm and a roughness difference rate ≤25% between the transverse and longitudinal directions. Improving the surface quality of foil materials used in metal photomasks is a pressing issue that metal photomask material suppliers need to address.

[0005] Currently, existing technologies mainly improve the surface quality of foil materials used in metal photomasks through the following two methods:

[0006] (1) The strip is treated as shown in the attached figure. Figure 1 The plate / strip shown is retarded using the traditional method, which involves two sets of retardation belts fixed in position for pressure grinding. The work rolls are treated as shown in the attached diagram. Figure 2 The work roll is refurbished using the traditional method, which involves using a refurbishing wheel that rotates continuously and rubs against the roll. The axial direction of the refurbishing wheel is parallel to the axial direction of the work roll, and the refurbishing marks left by the refurbishing wheel are always along the circumference of the roll.

[0007] (2) The strip is treated as shown in the attached figure. Figure 1The strip shown is ground using the traditional grinding method. During the cold rolling of the finished product, the work rolls in the preceding passes are ground using the traditional grinding method, and the last pass is rolled using laser-textured rolls to eliminate the difference in roughness between the transverse and longitudinal directions.

[0008] These two methods have the following two main shortcomings:

[0009] (1) Strip grinding: see attached Figure 1 The traditional grinding method for the plate / strip shown can easily cause continuous or discontinuous deep longitudinal scratches along the longitudinal direction of the strip. After multiple rolling processes, some scratches still remain on the surface of the strip and cannot be eliminated, resulting in excessive transverse roughness of the strip surface.

[0010] (2) Regarding work roll regrinding: For foil production, the surface condition of the work roll is a crucial factor affecting the foil surface, directly influencing its condition. Currently, there are two methods for work roll regrinding:

[0011] One is as attached Figure 2 The traditional grinding method shown for the work roll results in regular roller marks along the circumference of the work roll. During foil production, this causes longitudinal roller marks (commonly known as rolling lines) to appear on the surface of the foil, resulting in excessive differences in the roughness of the foil in the transverse and longitudinal directions, which cannot meet the high surface quality requirements of foil for metal photomasks.

[0012] Another method is to use laser texturing rolls in the final rolling pass of the finished product. Although this method can solve the problem of large differences in the horizontal and vertical roughness of the foil surface, the roll texturing treatment will bring two other disadvantages: First, the roll texturing treatment will accelerate the wear of the work rolls and shorten their service life; second, because the texturing rolls wear out quickly during use, the surface roughness of the foil produced in the early and late stages of the same batch of foil will be greatly different, which is not conducive to the stability of the final product.

[0013] To address the shortcomings of the aforementioned technologies, this invention provides a method for controlling the high surface quality of low-expansion alloy foil for high-precision metal photomasks. Summary of the Invention

[0014] To address the aforementioned shortcomings in existing technologies, this invention proposes a method for controlling the high surface quality of low-expansion alloy foil for high-precision metal photomasks, comprising:

[0015] (1) Hot rolling of alloy foil blanks to obtain a first plate / strip with a thickness of 2.0-6.0 mm;

[0016] (2) The first plate / strip is pickled to remove oxide scale, and then subjected to the first grinding process to obtain the second plate / strip with a roughness Ra≤0.65μm;

[0017] (3) The second plate / strip is subjected to a first cold rolling process, and then a second grinding process is performed to obtain a third plate / strip with a roughness Ra≤0.3μm;

[0018] (4) The third plate / strip is subjected to a second cold rolling process, wherein the second cold rolling process has N rolling passes, N≥3, and the Nth rolling pass has M rolling passes, M≥5; wherein, in the first to the N-1th rolling passes and in the first to the M-1th rolling passes of the Nth rolling pass, the work rolls (hereinafter referred to as work rolls) are used for rolling; in the Mth pass of the Nth rolling pass, the work rolls (hereinafter referred to as polishing rolls) are used for rolling; the work rolls are all ground using the work roll grinding process; the polishing rolls are first ground using the work roll grinding process and then polished using the polishing roll polishing process.

[0019] The first grinding process and the second grinding process include: using n sets of grinding wheels for grinding, each set of grinding wheels is independent of each other, the grinding wheel rotates along its own axis and makes periodic reciprocating motion along the width direction of the plate / strip, and the axis of the grinding wheel is perpendicular to the surface of the plate / strip.

[0020] The method for grinding the work roll includes: grinding the roll with a grinding wheel, wherein the grinding wheel rotates along its own axis and reciprocates along the length of the roll axis, and the axial direction of the grinding wheel is perpendicular to the length of the roll axis.

[0021] The polishing method for the polishing roller includes: using a polishing wheel to grind the roller, wherein the polishing wheel rotates along its own axis and reciprocates along the length of the roller axis, and the axial direction of the polishing wheel is perpendicular to the length of the roller axis.

[0022] The process parameters used in the first grinding process and the second grinding process can be the same or different.

[0023] In the first and second grinding processes, the number n of the n groups of grinding wheels is an integer in the range of 2 to 8; the number n of the grinding wheels in the first and second grinding processes can be the same or different from each other.

[0024] In the first and second grinding processes, each of the n groups of grinding wheels has at least two grinding wheels; the number of grinding wheels in each group in the first and second grinding processes can be the same or different; the number of grinding wheels in each group can be appropriately increased or decreased according to the strip width and the diameter of the grinding wheel, so as to ensure that the coverage area of ​​each group of grinding wheels during the movement process is at least completely covering the entire strip width range.

[0025] In the first and second grinding processes, the coverage area of ​​each grinding wheel during its movement is ensured to completely cover the width of the entire sheet / strip.

[0026] In the first and second grinding processes, the roughness of the grinding wheel gradually decreases from the first group to the nth group.

[0027] In the first and second grinding processes, the roughness of the grinding wheel can be determined based on the actual condition of the plate / strip.

[0028] The first cold rolling can only be carried out when the roughness Ra of the second plate / strip is ≤0.65μm.

[0029] In this process, after the sheet / strip is cold-rolled to a thickness of 0.80-1.20 mm through the first cold rolling process, the second grinding is then performed.

[0030] The first cold rolling process is carried out using a 6-roll mill.

[0031] In this process, after the roughness Ra of the plate / strip is processed to Ra≤0.3μm through the second grinding process, the second cold rolling process is then carried out.

[0032] The second cold rolling process is carried out using a 20-roll reversible rolling mill.

[0033] In the second cold rolling process, the total deformation of each rolling pass is ≥45%.

[0034] In the second cold rolling process, when the thickness of the sheet / strip is cold rolled to 0.06-0.14 mm (preferably 0.10 mm), the Nth rolling pass (i.e. the finished product rolling pass) is performed.

[0035] In the second cold rolling process, in the Nth rolling stroke (i.e. the finished product rolling stroke), a rolling mill with a diameter of 44-46 mm is used for rolling.

[0036] In the second cold rolling process, in the Nth rolling pass (i.e., the finished product rolling pass), the rolling of the first to the M-3rd passes (i.e., the passes before the third to last pass) is carried out using work rolls with a roughness Ra of 0.2-0.35μm, the rolling of the M-2nd pass (i.e., the third to last pass) is carried out using work rolls with a roughness Ra of 0.1-0.2μm, the rolling of the M-1st pass (i.e., the second to last pass) is carried out using work rolls with a roughness Ra of 0.08-0.1μm, and the rolling of the Mth pass (i.e., the last pass) is carried out using polishing rolls with a roughness Ra ≤ 0.07μm.

[0037] In the aforementioned method for grinding the working roll, the ratio of the rotational speed V1 of the grinding wheel to the rotational speed V2 of the working roll, V1 / V2, is ≥70.

[0038] Specifically, all rolls used in all rolling passes of the Nth rolling stroke are ground using the aforementioned work roll grinding method, and the surface roughness level of each roll is controlled according to different rolling passes.

[0039] Specifically, for the polishing roll used in the Mth pass (i.e., the last pass) of the Nth rolling stroke in the second cold rolling process, the work roll is first refurbished using the aforementioned work roll refurbishing method. The refurbishing wheel is a grinding wheel with a roughness Ra of 0.09-0.1μm. The roll is refurbished until there are no obvious lines on the surface. Three areas are randomly selected for inspection. The roll surface roughness Ra is considered qualified when it is 0.08-0.1μm. Then, the polishing roll is polished using the aforementioned polishing roll polishing method until the roll surface is bright. Three areas are randomly selected for inspection. The roll surface roughness Ra is considered qualified when it is ≤0.07μm. Thus, the polishing roll is obtained.

[0040] In particular, the intermediate annealing process is carried out no less than twice during the entire cold rolling process.

[0041] The present invention also provides a method for manufacturing a low-expansion alloy foil for high-precision metal masks, comprising using the high surface quality control method for low-expansion alloy foil for high-precision metal masks as described above to control the surface quality of the low-expansion alloy foil.

[0042] The present invention also provides a low-expansion alloy foil for high-precision metal masks, which is manufactured by the low-expansion alloy foil manufacturing method described above, wherein the thickness of the low-expansion alloy foil is not greater than 0.04 mm and the difference rate of transverse and longitudinal roughness is ≤25%.

[0043] The present invention has the following beneficial technical effects:

[0044] 1. In the method for controlling the high surface quality of low-expansion alloy foil according to the present invention, the plate / strip undergoes a first grinding process and a second grinding process. The first grinding process and the second grinding process described in the present invention have the following advantages:

[0045] (1) The grinding marks of the first grinding process and the second grinding process described in this invention are random and have no specific directionality, which avoids the excessive grinding marks caused by grinding in the same direction in the traditional grinding method, which ultimately affects the surface quality of the finished product of the plate / strip.

[0046] (2) The first grinding treatment and the second grinding treatment described in this invention can use multi-stage grinding wheels. According to the surface quality requirements of the plate / strip, the surface of the plate / strip can be simultaneously subjected to rough grinding, fine grinding and other grinding treatments, thereby improving the surface quality of the plate / strip.

[0047] (3) The first grinding process and the second grinding process described in this invention can improve grinding efficiency.

[0048] (4) The first grinding treatment and the second grinding treatment described in this invention can reduce the surface roughness of the plate / strip after grinding, and can reduce the difference in the transverse and longitudinal roughness of the foil, thereby improving the surface quality of the plate / strip.

[0049] 2. In the method for controlling the high surface quality of low-expansion alloy foil described in this invention, the work rolls used in the second cold rolling process are all refurbished using a work roll refurbishment method. This work roll refurbishment method has the following advantages: Traditional work roll refurbishment methods result in work rolls with a single circumferential groove after refurbishment. This single circumferential groove is the main reason for the large difference in transverse and longitudinal roughness of the foil surface. That is, during strip rolling, it will cause clear longitudinal grooves (commonly known as rolling lines) to form on the surface of the sheet / strip, resulting in a large difference in transverse and longitudinal roughness of the sheet / strip. The purpose of the work roll refurbishment method described in this invention is to form non-circumferential grooves on the roll surface. That is, the surface of the roll refurbished by the work roll refurbishment method described in this invention does not have obvious unidirectional refurbishment marks or obvious grooves in a specific direction. This avoids the circumferential grooves caused by traditional roll refurbishment methods, reduces the impact of the roll on the difference in transverse and longitudinal roughness of the strip surface, reduces the difference in transverse and longitudinal roughness of the foil surface, and is conducive to improving the surface quality of the foil.

[0050] 3. In the method for controlling the high surface quality of low expansion alloy foil described in this invention, the polishing rollers used in the last pass of the second cold rolling are all polished using a polishing roller polishing treatment method. This polishing treatment further eliminates the difference in transverse and longitudinal roughness of the foil caused by the texture of the rollers themselves.

[0051] 4. The low-expansion alloy foil for high-precision metal photomasks prepared by the method of the present invention has a thickness of no more than 0.04 mm and a roughness difference rate of ≤25% in the transverse and longitudinal directions. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the traditional grinding method for sheet / strip materials.

[0053] Figure 2 This is a schematic diagram of the traditional grinding method for work rolls.

[0054] Figure 3 This is a schematic diagram of the first and second grinding processes described in this invention.

[0055] Figure 4 This is a schematic diagram of the work roll grinding method described in this invention.

[0056] Figure 5 This is a schematic diagram of the polishing roller polishing method described in this invention. Detailed Implementation

[0057] The present invention will now be described in further detail with reference to specific embodiments. However, it should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the claims of this application.

[0058] Figure 1 The diagram shows a traditional grinding process for sheet / strip materials. In the diagram, reference numeral A1 indicates the sheet / strip material to be ground, and reference numerals B1 and C1 indicate the grinding belts. The grinding of sheet / strip materials is performed using a pressure grinding method with two sets of grinding belts fixed in position.

[0059] Figure 2 The diagram shows a traditional method for regrinding work rolls. In the diagram, reference numeral A2 indicates the work roll to be regrinded, and reference numeral B2 indicates the regrinding wheel. The regrinding wheel's axis is parallel to the work roll's axis, and the wheel rotates along its own axis while reciprocating along the length of the work roll's axis.

[0060] The high-precision metal mask high-expansion alloy foil high surface quality control method of the present invention includes:

[0061] (1) Hot rolling of alloy foil blanks to obtain a first plate / strip with a thickness of 2.0-6.0 mm;

[0062] (2) The first plate / strip is pickled to remove oxide scale, and then subjected to the first grinding process to obtain the second plate / strip with a roughness Ra≤0.65μm;

[0063] (3) The second plate / strip is subjected to a first cold rolling process, and then a second grinding process is performed to obtain a third plate / strip with a roughness Ra≤0.3μm;

[0064] (4) The third plate / strip is subjected to a second cold rolling process, wherein the second cold rolling process has N rolling passes, N≥3, and the Nth rolling pass has M rolling passes, M≥5; wherein, in the first to the N-1th rolling passes and in the first to the M-1th rolling passes of the Nth rolling pass (i.e. the finished product rolling pass), work rolls are used for rolling; in the Mth pass of the Nth rolling pass, polishing rolls are used for rolling; the work rolls are all ground using the work roll grinding process; the polishing rolls are first ground using the work roll grinding process and then polished using the polishing roll polishing process.

[0065] The first and second grinding processes include: using n sets of grinding wheels for grinding, each set of grinding wheels operating independently. Each grinding wheel rotates along its own axis and performs periodic reciprocating motion along the width direction of the sheet / strip, with the axis of the grinding wheel perpendicular to the surface of the sheet / strip. Specifically, as follows... Figure 3 As shown in the attached diagram, reference numeral A3 indicates the plate / strip to be retarded, the left arrow indicates the direction of movement of the plate / strip, and reference numeral B3 indicates the retarding wheel. The number of retarding wheels in each group can be adjusted according to the width of the plate / strip to be retarded and the diameter of the retarding wheel, ensuring that each group of retarding wheels completely covers the width of the plate / strip during retardation. The number of retarding wheel groups is n (n ranges from 2 to 8), and can be appropriately increased or decreased according to the surface requirements of the plate / strip to be retarded. The grit size of each group of retarding wheels can be adjusted according to the quality requirements of the plate / strip to be retarded, but the roughness of the retarding wheels gradually decreases from group 1 to group n. In addition to rotating along its own axis, each group of retarding wheels also performs periodic reciprocating motion along the width direction of the plate / strip, as shown in the attached diagram. Figure 3 As indicated by the up and down arrows. Furthermore, the axial direction of the grinding wheel is perpendicular to the surface of the sheet / strip.

[0066] After the first grinding process, the surface roughness Ra of the sheet / strip must be ≤0.65μm before the first cold rolling can be carried out.

[0067] After the second grinding process, the surface roughness Ra of the sheet / strip must be ≤0.3μm before it can enter the second cold rolling process.

[0068] The method for grinding the work roll includes grinding the roll with a grinding wheel, wherein the grinding wheel rotates along its own axis and reciprocates along the length of the roll axis, and the axial direction of the grinding wheel is perpendicular to the length of the roll axis. Figure 4A schematic diagram of the work roll regrinding method described in this invention is shown. In the diagram, reference numeral A4 represents the work roll, and reference numeral B4 represents the regrinding wheel. In addition to rotating along its own axial direction, the regrinding wheel also reciprocates along the length of the work roll axis, and the axial direction of the regrinding wheel is perpendicular to the length of the roll axis. The ratio of the rotational speed V1 of the regrinding wheel to the rotational speed V2 of the roll, V1 / V2, is ≥ 70.

[0069] The polishing method of the polishing roller includes: using a polishing wheel to grind the roll, wherein the polishing wheel rotates along its own axis and reciprocates along the length of the roll axis, and the axial direction of the polishing wheel is perpendicular to the length of the roll axis. Figure 5 A schematic diagram of the polishing roller polishing method of the present invention is shown. In the diagram, reference numeral A5 represents the roller to be polished, and reference numeral B5 represents the polishing wheel. In addition to rotating along its own axial direction, the polishing wheel also reciprocates along the length of the roller axis, and the axial direction of the polishing wheel is perpendicular to the length of the roller axis.

[0070] Example

[0071] This embodiment provides a method for controlling the high surface quality of low-expansion alloy foil for high-precision metal photomasks, including:

[0072] (1) Hot rolling of alloy foil blank to obtain a first plate / strip with a thickness of 4mm;

[0073] (2) The first plate / strip is pickled to remove oxide scale, and then subjected to the first grinding process to obtain a second plate / strip with a roughness Ra of 0.63 μm;

[0074] (3) The second plate is subjected to a first cold rolling process using a 6-roll mill to a thickness of 1.0 mm, and then subjected to a second grinding process to obtain a third strip with a roughness Ra of 0.27 μm.

[0075] (4) The third strip is subjected to a second cold rolling process using a 20-roll reversible rolling mill. The second cold rolling process has three rolling passes, and the deformation amount of each rolling pass is not less than 45%.

[0076] Specifically, in the second cold rolling process, the total deformation in the first rolling pass is 70%, and the thickness is rolled from 1.0 mm to 0.3 mm; the total deformation in the second rolling pass is 72%, and the thickness is rolled from 0.3 mm to 0.083 mm; finally, in the third rolling pass, which is the finished product rolling pass, the total deformation is 71%, and the thickness is rolled from 0.083 mm to 0.024 mm.

[0077] Specifically, in the aforementioned third rolling pass (i.e., the finished product rolling pass), a total of 7 rolling passes were performed. The work rolls used in passes 1-4 had a surface roughness Ra of 0.25 μm, the work rolls used in pass 5 had a surface roughness Ra of 0.15 μm, the work rolls used in pass 6 had a surface roughness Ra of 0.08 μm, and the polishing rolls used in pass 7 (the final pass) had a surface roughness Ra of 0.065 μm. All rolls used in the third rolling pass had a diameter of 44 mm.

[0078] In the rolling process of the first to the sixth pass of the third rolling pass in the second cold rolling treatment, the following method is adopted: Figure 4 The work rolls shown are ground using the grinding method and then rolled.

[0079] In the seventh pass of the third rolling mill of the second cold rolling process, a polishing roll is used for rolling. The polishing roll is first subjected to the following process: Figure 4 The work roll is refurbished using the method shown, and refurbished to a roughness of 0.08 μm. Then, it is processed as follows: Figure 5 The polishing roller shown is polished until the roughness Ra of the roller is 0.065 μm, which is considered qualified, and thus the polishing roller is obtained.

[0080] Among them, such as Figure 4 The work roll grinding method shown includes: grinding the roll with a grinding wheel, wherein the grinding wheel rotates along its own axis and reciprocates along the length of the roll axis, and the axial direction of the grinding wheel is perpendicular to the length of the roll axis.

[0081] Among them, such as Figure 5 The polishing method shown includes: using a polishing wheel to grind the roll, wherein the polishing wheel rotates along its own axis and reciprocates along the length of the roll axis, and the axial direction of the polishing wheel is perpendicular to the length of the roll axis.

[0082] The rolling process for the third rolling pass (i.e., the finished product rolling pass) is shown in Table 1.

[0083] Table 1 Rolling parameters for the third rolling stroke in the embodiment.

[0084] Rolling passes Inlet thickness (mm) Export thickness (mm) Deformation per pass (%) First round 0.083 0.06 27.7％ Second lane 0.06 0.045 25.0％ 3rd lane 0.045 0.038 15.6％ 4th lane 0.038 0.033 13.2％ 5th course 0.033 0.029 12.1％ 6th lane 0.029 0.026 10.3％ 7th lane 0.026 0.024 7.7％

[0085] Comparative Example 1

[0086] The foil material of Comparative Example 1 was produced using a process that was substantially the same as that used in the examples, except for the following differences:

[0087] (1) In the embodiment, the first plate / strip after acid pickling and descaling is subjected to the following process: Figure 3The first grinding process shown yields the second sheet / strip; while in Comparative Example 1, the first sheet after acid pickling and descaling is subjected to the following process... Figure 1 The plate / strip shown is ground using the traditional grinding method.

[0088] (2) In the embodiment, the second strip after the first cold rolling process is subjected to the following process: Figure 3 The second grinding process shown yields the third strip; while in Comparative Example 1, the second strip after the first cold rolling process is subjected to the following process: Figure 1 The plate / strip shown is ground using the traditional grinding method.

[0089] (3) In the embodiment, the work rolls used in the rolling of the 6th pass of the 1st to 3rd passes of the second cold rolling process are all as follows: Figure 4 The work rolls are ground using the method shown in Comparative Example 1; however, in Comparative Example 1, all work rolls are ground using the method described in the previous example. Figure 2 The work roll shown is refurbished using the traditional refurbishing method.

[0090] (4) In the embodiment, the 7th pass of the 3rd rolling stroke of the second cold rolling process uses a polishing roll, which first uses a polishing roll as described above. Figure 4 The work roll is refurbished using the method shown, and then... Figure 5 The polishing process is performed using the polishing roller polishing method shown; however, in Comparative Example 1, the 7th pass of the 3rd rolling stroke in the second cold rolling process still uses the method described above. Figure 2 The work roll shown is ground using the traditional grinding method and then rolled.

[0091] (5) In this embodiment, for the rolling of the 7 passes of the 3rd rolling stroke in the second cold rolling process, the surface roughness Ra of the work rolls used in passes 1-4 is 0.25 μm, the surface roughness Ra of the work rolls used in pass 5 is 0.15 μm, the surface roughness Ra of the work rolls used in pass 6 is 0.08 μm, and the surface roughness Ra of the polishing rolls used in pass 7 is 0.065 μm; while in Comparative Example 1, for the rolling of the 7 passes of the 3rd rolling stroke in the second cold rolling process, the surface roughness Ra of the work rolls used in passes 1-4 is 0.25 μm, the surface roughness Ra of the work rolls used in pass 5 is 0.15 μm, and the surface roughness Ra of the work rolls used in passes 6-7 is 0.08 μm. The specific rolling parameters of the 3rd rolling stroke are shown in Table 1.

[0092] The surface roughness of the foils rolled in Examples 1 and Comparative Example 1 was tested, and the results are shown in Table 2. The difference rate between transverse and longitudinal roughness is calculated as (mean transverse roughness - mean longitudinal roughness) / mean transverse roughness × 100%.

[0093] As shown in Table 2, the average longitudinal roughness of the foil rolled by the process of Comparative Example 1 is 0.076 μm, and the average transverse roughness is 0.109 μm. The calculated difference rate between the transverse and longitudinal roughness of the foil of Comparative Example 1 is 30.3%. In contrast, the average longitudinal roughness of the foil rolled by the process of the Example is 0.061 μm, and the average transverse roughness is 0.063 μm, with a difference rate of 3.2% between the transverse and longitudinal roughness. The comparison of the roughness difference rate data shows that the surface quality of the foil produced by the method of this invention is far superior to that of the foil produced by traditional processes.

[0094] Comparative Example 2

[0095] The foil production of Comparative Example 2 was carried out using a process flow that was basically the same as that of Comparative Example 1, except for the following differences: the rolling process of the first 6 passes of the third rolling process of the second cold rolling treatment of Comparative Example 2 was the same as that of Comparative Example 1. The only difference was that the seventh pass of the third rolling process of the second cold rolling treatment of Comparative Example 2 used a laser texturing roll for rolling, and the roughness Ra of the laser texturing roll was 0.08 μm.

[0096] Roughness tests were performed on samples of the foils prepared in Examples 1 and 2, and the results are shown in Tables 2-4.

[0097] As shown in Table 2, the average transverse roughness of the foil produced by the process in Comparative Example 2 is 0.087 μm, and the average longitudinal roughness is 0.082 μm, with a difference rate of 5.7% between transverse and longitudinal roughness. In contrast, the difference rate between transverse and longitudinal roughness of the foil produced by the process in this embodiment of the invention is 3.2%. It can be seen from Comparative Example 2 that the difference rate between transverse and longitudinal roughness in this embodiment of the invention is slightly better than that of the foil rolled by the laser texturing roller in Comparative Example 2, but the difference is not significant.

[0098] However, as mentioned earlier, the laser texturing roller used in Comparative Example 2 wears out quickly, resulting in a large difference in the roughness of the obtained foil at both ends. As shown in Table 4, the transverse difference rate of the foil at the head and tail of Comparative Example 2 is 16.1%, and the longitudinal difference rate is 20.7%, while the transverse difference rate of the foil at the head and tail of the embodiment of the present invention is 8%, and the longitudinal difference rate is 8.2%, which is much smaller than that of Comparative Example 2.

[0099] Table 2. Roughness test results of the examples and comparative examples – head sampling

[0100]

[0101] Table 3. Roughness results of the examples and comparative examples – tail sampling

[0102]

[0103] Table 4 Comparison of head and tail roughness differences between the examples and comparative examples

[0104]

[0105] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0106] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

[0107] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A method for controlling the high surface quality of low-expansion alloy foil for high-precision metal photomasks, comprising: (1) Hot rolling of alloy foil blanks to obtain the first plate / strip; (2) The first plate / strip is pickled to remove oxide scale, and then subjected to the first grinding process to obtain the second plate / strip with a roughness Ra≤0.65μm; (3) The second plate / strip is subjected to a first cold rolling process and then a second grinding process to obtain a third plate / strip with a roughness Ra≤0.3μm; (4) The third plate / strip is subjected to a second cold rolling process, wherein the second cold rolling process has N rolling passes, N≥3, and the Nth rolling pass has M rolling passes, M≥5; wherein, in the first to N-1 rolling passes and in the first to M-1 rolling passes of the Nth rolling pass, the work rolls are ground; and in the Mth pass of the Nth rolling pass, the polishing rolls are used. The working rollers are all ground using the working roller grinding treatment method; the polishing rollers are first ground using the working roller grinding treatment method, and then polished using the polishing roller polishing treatment method. The first grinding process and the second grinding process include: using n sets of grinding wheels for grinding, each set of grinding wheels is independent of each other, the grinding wheel rotates along its own axis and makes periodic reciprocating motion along the width direction of the plate / strip, and the axis of the grinding wheel is perpendicular to the surface of the plate / strip. The method for grinding the work roll includes: grinding the roll with a grinding wheel, wherein the grinding wheel rotates along its own axis and reciprocates along the length of the roll axis, and the axial direction of the grinding wheel is perpendicular to the length of the roll axis. The polishing roller polishing method includes: polishing the roll with a polishing wheel, wherein the polishing wheel rotates along its own axis and reciprocates along the length of the roll axis, and the axial direction of the polishing wheel is perpendicular to the length of the roll axis.

2. The method for controlling high surface quality of low-expansion alloy foil as described in claim 1, wherein, In the first and second grinding processes, the coverage area of ​​each grinding wheel during its movement is ensured to completely cover the width of the entire sheet / strip.

3. The method for controlling high surface quality of low-expansion alloy foil as described in claim 1, wherein, In the first and second grinding processes, the roughness of the grinding wheel gradually decreases from the first group to the nth group.

4. The method for controlling high surface quality of low-expansion alloy foil as described in claim 1, wherein, The thickness of the first sheet / strip is 2.0-6.0 mm, and after the first cold rolling process, the thickness of the sheet / strip is 0.80-1.20 mm.

5. The method for controlling high surface quality of low-expansion alloy foil as described in claim 1, wherein, In the second cold rolling process, the total deformation of each rolling pass is ≥45%.

6. The method for controlling high surface quality of low-expansion alloy foil as described in claim 1, wherein, In the second cold rolling process, when the thickness of the sheet / strip is cold rolled to 0.06-0.14 mm, the Nth rolling pass is performed.

7. The method for controlling high surface quality of low-expansion alloy foil as described in claim 1, wherein, In the second cold rolling process, in the Nth rolling pass, the rolling of the first to the M-3th passes is carried out using work rolls with a roughness Ra of 0.2-0.35 μm, the rolling of the M-2nd pass is carried out using work rolls with a roughness Ra of 0.1-0.2 μm, the rolling of the M-1st pass is carried out using work rolls with a roughness Ra of 0.08-0.1 μm, and the rolling of the Mth pass is carried out using polishing rolls with a roughness Ra ≤ 0.07 μm.

8. The method for controlling high surface quality of low-expansion alloy foil as described in claim 1, wherein, In the aforementioned work roll grinding method, the rotational speed of the grinding wheel is... V1 Rotation speed of the work roll V2 ratio V1 / V2 ≥70.

9. A method for manufacturing a low-expansion alloy foil for a high-precision metal mask, comprising controlling the surface quality of the low-expansion alloy foil using the high surface quality control method for the low-expansion alloy foil for a high-precision metal mask as described in any one of claims 1-8.

10. A low-expansion alloy foil for high-precision metal photomasks, which is manufactured by the manufacturing method of the low-expansion alloy foil as described in claim 9, wherein the thickness of the low-expansion alloy foil is not greater than 0.04 mm and the difference rate of transverse and longitudinal roughness is ≤25%.

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