A method for manufacturing a high-precision reflective metal code disk

Abstract

The present invention provides a method for manufacturing a high-precision reflective metal code disk, relating to the technical field of code disk processing. The method achieves code disk line accuracy through magnetron sputtering coating and photolithography. Double-sided alignment, exposure, and development are used to create the code disk photoresist profile, followed by stainless steel etching to ensure dimensional accuracy. The metal code disk produced by combining these two processes can achieve line accuracy of ±1μm, inner and outer diameter dimensional accuracy of ±5μm, and concentricity accuracy of the pattern and inner circle of the code disk within 5μm.

Description

Technical Field

[0001] The present invention relates to the technical field of code disc processing, and in particular to a method for manufacturing a high-precision reflective metal code disc. Background Art

[0002] With the diversification of the application fields of photoelectric encoders, the external environment of some photoelectric encoders is relatively harsh. Photoelectric encoders assembled with common glass code discs and resin code discs have unstable performance characteristics (code disc fogging, deformation, etc.) in these harsh environments. Given the stable characteristics of metal, the demand for metal encoder code discs is gradually expanding. The types of metal code discs are mainly divided into transmissive metal code discs and reflective metal code discs.

[0003] A common method for manufacturing metal transmissive code disks is to create translucent stripes on the surface of stainless steel by photolithography and wet etching. However, the line accuracy of this code disk is approximately ±5μm, which is poor and cannot meet the assembly requirements of some high-precision encoders.

[0004] A common method for producing metal reflective code disks is to coat a low-reflective metal film on the metal surface, then photolithographically produce a reflective code disk pattern with alternating light and dark elements on the metal film layer, and then cut the formed code disk pattern according to the code disk's shape to produce a code disk. The metal code disk produced by this process has greatly improved line width accuracy, which can be achieved to ±1μm. However, since the code disk is produced by CNC (numerical control) machine tools or laser cutting, the inner and outer diameters and concentricity of the code disk cannot be achieved with ultra-high precision (i.e., inner diameter within ±5μm, concentricity within 5μm), so it is difficult to produce a code disk with an outer size accuracy of less than 5μm through this method. Summary of the Invention

[0005] The object of the present invention is to provide a method for manufacturing a high-precision reflective metal code disk, which can simultaneously meet the line accuracy and external dimensional accuracy requirements of the reflective metal code disk.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for manufacturing a high-precision reflective metal code disk, comprising the following steps:

[0008] A low-reflection film layer is deposited on the surface of a stainless steel substrate by magnetron sputtering;

[0009] Performing photolithography on the surface of the low-reflection film layer to form a code disk pattern, thereby obtaining a stainless steel substrate with the code disk pattern;

[0010] Photoresist is coated on the upper and lower surfaces of the stainless steel substrate with the code disk pattern, dried, and then placed in a double-sided alignment exposure machine. A mask with a code disk shape is used at the upper and lower ends of the double-sided alignment exposure machine. The upper and lower masks are aligned with the stainless steel substrate and double-sided exposure is performed. The mask is then taken out for double-sided development to form a code disk shape on the upper and lower surfaces of the stainless steel substrate.

[0011] The stainless steel substrate with the code disk shape is wet-etched and the photoresist is removed to obtain a high-precision reflective metal code disk.

[0012] Preferably, before coating the low-reflection film layer, the method further includes: cleaning the stainless steel substrate.

[0013] Preferably, the low-reflection film layer includes a low-reflection chromium film.

[0014] Preferably, the reflectivity of the low-reflection film layer at 850 nm is ≤2%.

[0015] Preferably, the low-reflection chrome film includes a stacked Cr film and a CrO film.

[0016] Preferably, the thickness of the Cr film and the CrO film are both 70 nm.

[0017] Preferably, the photolithography comprises: coating a photoresist on the surface of the low-reflection film layer, and then sequentially performing exposure, development, wet etching and removing the photoresist.

[0018] Preferably, the line accuracy of the high-precision reflective metal code disk is ±1 μm, the inner and outer diameter size accuracy is ±5 μm, and the concentricity accuracy of the pattern and the inner and outer circles is within 5 μm.

[0019] Preferably, the wet etching uses a stainless steel etching solution; the stainless steel etching solution is a mixture of ferric chloride solution and concentrated hydrochloric acid.

[0020] Preferably, the concentration of the ferric chloride solution is 3 mol / L; the mass fraction of the concentrated hydrochloric acid is 36%; and the volume ratio of the ferric chloride solution to the concentrated hydrochloric acid is 97:3.

[0021] The present invention provides a method for manufacturing a high-precision reflective metal code disk, comprising the following steps: plating a low-reflection film layer on the surface of a stainless steel substrate by magnetron sputtering; performing photoetching on the surface of the low-reflection film layer to form a code disk pattern, thereby obtaining a stainless steel substrate with a code disk pattern; coating photoresist on the upper and lower surfaces of the stainless steel substrate with the code disk pattern, drying the surface, and then placing the surface in a double-sided alignment exposure machine, wherein the upper and lower ends of the double-sided alignment exposure machine each use a mask with a code disk shape, aligning the upper and lower masks with the stainless steel substrate, performing double-sided exposure, and then taking the mask out for double-sided development, thereby forming a code disk outline on the upper and lower surfaces of the stainless steel substrate; and wet-etching the stainless steel substrate with the code disk outline to remove the photoresist, thereby obtaining a high-precision reflective metal code disk.

[0022] The present invention achieves the line accuracy of the code disk through the process of magnetron sputtering coating + photolithography, and ensures the dimensional accuracy of the code disk by making the code disk photoresist shape through double-sided alignment exposure and development and stainless steel etching. The line accuracy of the metal code disk produced by combining the above two processes can reach ±1μm, the inner and outer diameter dimensional accuracy of the code disk can reach ±5μm, and the concentricity accuracy of the pattern and the inner circle can reach within 5μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a stainless steel substrate with a code disc pattern;

[0024] Figure 2 Two mask patterns for double-sided alignment exposure;

[0025] Figure 3 This is a physical picture of the reflective metal code disk prepared in Example 1. DETAILED DESCRIPTION

[0026] The present invention provides a method for manufacturing a high-precision reflective metal code disk, comprising the following steps:

[0027] A low-reflection film layer is deposited on the surface of a stainless steel substrate by magnetron sputtering;

[0028] Performing photolithography on the surface of the low-reflection film layer to form a code disk pattern, thereby obtaining a stainless steel substrate with the code disk pattern;

[0029] Photoresist is coated on the upper and lower surfaces of the stainless steel substrate with the code disk pattern, dried, and then placed in a double-sided alignment exposure machine. A mask with a code disk shape is used at the upper and lower ends of the double-sided alignment exposure machine. The upper and lower masks are aligned with the stainless steel substrate and double-sided exposure is performed. The mask is then taken out for double-sided development to form a code disk shape on the upper and lower surfaces of the stainless steel substrate.

[0030] The stainless steel substrate with the code disk shape is wet-etched and the photoresist is removed to obtain a high-precision reflective metal code disk.

[0031] The present invention plates a low-reflection film layer on the surface of a stainless steel substrate by magnetron sputtering.

[0032] The present invention preferably selects a suitable stainless steel substrate based on the material, thickness and other parameters of the code disc specified in the customer's drawing.

[0033] Before applying the low-reflection film, the present invention preferably cleans the stainless steel substrate. In the present invention, the cleaning is preferably ultrasonic cleaning followed by rinsing with pure water. The cleaning solution used for the ultrasonic cleaning is preferably a strong alkaline solution. The present invention has no particular requirements for the type of strong alkaline solution; any strong alkaline solution well known in the art can be used. After the cleaning is completed, the present invention preferably evaporates the cleaned stainless steel substrate with IPA.

[0034] In the present invention, the low-reflection film layer preferably includes a low-reflection chromium film. In the present invention, the reflectivity of the low-reflection film layer at 850nm is preferably ≤2%. The present invention has no special requirements for the composition of the low-reflection chromium film, and any low-reflection chromium film well known in the art can be used. In an embodiment of the present invention, the low-reflection chromium film is preferably a stacked Cr film + CrO film. In the present invention, the thickness of the Cr film and the CrO film are preferably 70nm. When the low-reflection chromium film is a stacked Cr film + CrO film, the magnetron sputtering conditions preferably include: the Cr target sputtering power is 5kW, the Ar gas flow rate is 30sccm / s when sputtering the Cr film, and the sputtering of the CrO film is carried out in an Ar-N2-CO2 mixed gas atmosphere, with the Ar flow rate being 30sccm / s, the N2 flow rate being 60sccm / s, and the CO2 flow rate being 120sccm / s.

[0035] After forming the reflective film layer, the present invention performs photoetching on the surface of the low-reflective film layer to form a code disk pattern, thereby obtaining a stainless steel substrate with the code disk pattern.

[0036] Before the photolithography, the present invention preferably performs ultrasonic cleaning on the stainless steel substrate with the low-reflection film layer attached thereto.

[0037] In the present invention, the photolithography preferably includes: coating a photoresist on the surface of the low-reflection film layer, and then sequentially performing exposure, development, wet etching and removing the photoresist to form a code disk pattern.

[0038] In the present invention, the photoresist is preferably a positive photoresist; in an embodiment of the present invention, it is specifically SUN-115P 10cp positive photoresist. The positive photoresist used in the present invention can be dissolved in an alkaline developer after ultraviolet light exposure. In the present invention, the coating is preferably spin coating, and the spin coating speed is preferably 2500rpm. In the present invention, the thickness of the photoresist coating is preferably 1μm. In the present invention, the exposure is preferably ultraviolet exposure; the exposure light intensity is preferably 12mW / cm 2 , the exposure time is preferably 10s. In the present invention, the development is preferably to soak the exposed substrate with a TMAH solution with a mass fraction of 2.38% for 30s. The present invention removes the photoresist of the exposed part by development to form a photoresist pattern. In the present invention, the etching solution used in the wet etching is preferably ammonium cerium nitrate etching solution; the ammonium cerium nitrate etching solution is preferably obtained by mixing pure water, glacial acetic acid and ammonium cerium nitrate, and the amount ratio of the pure water, glacial acetic acid and ammonium cerium nitrate is preferably 6000mL:220mL:1200g. In the present invention, the low-reflection film layer that is not protected by the photoresist is etched away by wet etching, leaving the required code disk pattern. In the present invention, the degumming solution used to remove the photoresist is preferably a positive photoresist stripping solution. The present invention preferably removes the residual photoresist on the surface of the code disk by immersion ultrasound. After removing the photoresist, the present invention preferably also includes cleaning the stainless steel substrate after degumming to obtain a stainless steel substrate with a code disk pattern (such as Figure 1 In the present invention, the cleaning is preferably carried out by soaking in concentrated sulfuric acid and then ultrasonic cleaning.

[0039] After obtaining a stainless steel substrate with a code disk pattern, the present invention coats SUN-115P 100cp photoresist on the upper and lower surfaces of the stainless steel substrate with the code disk pattern, dries it, and then places it in a double-sided alignment exposure machine. The upper and lower ends of the double-sided alignment exposure machine each use a mask with a code disk shape. After aligning the upper and lower masks with the stainless steel substrate, double-sided exposure is performed, and then taken out for double-sided development to form the code disk shape of the photoresist on the upper and lower surfaces of the stainless steel substrate.

[0040] In the present invention, the photoresist coating is preferably performed using a glue sprayer; in the present invention, the type of the photoresist is preferably the same as the photoresist used in preparing the code disk pattern, which will not be repeated here. In the present invention, the thickness of the photoresist is preferably 7 μm.

[0041] In the present invention, the mask and the stainless steel substrate are preferably provided with alignment mark patterns. The present invention has no special requirements for the double-sided exposure and double-sided development, and the exposure and development processes well known in the art can be used. In the embodiment of the present invention, the exposure conditions are: the exposure light intensity is 12mW / cm 2The exposure time is 10s, and then the exposed product is immersed in a TMAH solution with a mass fraction of 2.5% for 30s for development. After double-sided development, the double-sided code disk photoresist shape (annular outline) is exposed.

[0042] In the present invention, the wet etching preferably uses a stainless steel etching solution; the stainless steel etching solution is preferably a mixture of 3 mol / L ferric chloride solution and 36% concentrated hydrochloric acid, and the volume ratio of the ferric chloride solution to the concentrated hydrochloric acid is preferably 97:3.

[0043] The present invention leaves a final high-precision reflective metal code disk after wet etching.

[0044] The present invention achieves the line accuracy of the code disk through magnetron sputtering coating + photolithography, and ensures the dimensional accuracy of the code disk by making the code disk photoresist shape through double-sided alignment exposure and development and stainless steel etching. The line accuracy of the metal code disk produced by combining the above two processes can reach ±1μm, the inner and outer diameter dimensional accuracy of the code disk can reach ±5μm, and the concentricity accuracy of the pattern and the inner and outer circles can reach within 5μm.

[0045] The following describes in detail the method for manufacturing the high-precision reflective metal code disk provided by the present invention in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] A metal reflective code disk with an inner diameter of 11.007 mm, an outer diameter of 26.395 mm, and a line width of 0.0374 mm was prepared.

[0048] After ultrasonic cleaning with a professional cleaning agent, rinsing with pure water, and IPA evaporation, the stainless steel substrate is plated with a low-reflection chromium film on the smooth surface of the stainless steel using a magnetron sputtering coating machine. The low-reflection chromium film includes a stacked Cr film and a CrO film, both with a thickness of 70nm. The coating conditions are as follows: the Cr target sputtering power is 5kW, the Ar gas flow rate is 30sccm / s when sputtering the Cr film, the Ar flow rate is 30sccm / s when sputtering the CrO film, the N2 flow rate is 60sccm / s, and the CO2 flow rate is 120sccm / s. After the film performance is tested and qualified by an Olympus reflectivity tester, SUN-115P 10cp positive photoresist is spin-coated on the surface of the low-reflection chromium film, and the rotation speed is preferably 2500rmp / min. The exposure light intensity is 12mW / cm 2, the exposure time is 10s, and it is immersed in a TMAH solution with a mass fraction of 2.38% for 30s for development; the chromium film is wet-etched using an ammonium cerium nitrate etching solution, which consists of pure water, glacial acetic acid and nitric acid. The etching solution includes 6000mL pure water, 220mL glacial acetic acid and 1200g ammonium cerium nitrate; thereafter, the photoresist is removed and cleaned to obtain a stainless steel substrate with a code disk pattern, such as Figure 1 As shown;

[0049] The positive photoresist is sprayed on the upper and lower surfaces of the stainless steel substrate with the code disk pattern by a sprayer and dried. The film thickness is 7μm. After completion, the two masks are aligned by a double-sided alignment exposure machine. After alignment, the product is placed and aligned, and then double-sided exposure is performed. The exposure conditions are: exposure light intensity is 12mW / cm 2 The exposure time is preferably 10s, and then the exposed product is immersed in a 2.5% TMAH solution for 30s for development (such as Figure 2 As shown in the figure), the outer pattern made of photoresist is generated on the front and back respectively. Finally, the stainless steel substrate that has completed the above processes is wet-etched by stainless steel etching liquid. The non-protected area is etched, and the area protected by the photoresist is etched to form the final metal code disk. The actual picture is as shown in the figure Figure 3 shown.

[0050] A number of metal reflective code disks were prepared according to the above method, and the dimensions are shown in Table 1 below.

[0051] Table 1 Dimensions of metal reflective code discs

[0052]

[0053] As shown in Table 1, the line accuracy of the metal code disk prepared by the present invention reaches ±1 μm, the inner and outer diameter dimensional accuracy of the code disk reaches ±5 μm, and the concentricity accuracy of the pattern and the inner and outer circles is within 5 μm.

[0054] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for manufacturing a high-precision reflective metal code disk, characterized in that: The following steps are involved: A low-reflection film layer is deposited on the surface of a stainless steel substrate by magnetron sputtering; Performing photolithography on the surface of the low-reflection film layer to form a code disk pattern, thereby obtaining a stainless steel substrate with the code disk pattern; Photoresist is coated on the upper and lower surfaces of the stainless steel substrate with the code disk pattern, dried, and then placed in a double-sided alignment exposure machine. A mask with a code disk shape is used at the upper and lower ends of the double-sided alignment exposure machine. The upper and lower masks are aligned with the stainless steel substrate and double-sided exposure is performed. The mask is then taken out for double-sided development to form a code disk shape on the upper and lower surfaces of the stainless steel substrate. The stainless steel substrate with the code disk shape is wet-etched and the photoresist is removed to obtain a high-precision reflective metal code disk.

2. The production method according to claim 1, characterized in that Before coating the low-reflection film layer, the method further includes: cleaning the stainless steel substrate.

3. The production method according to claim 1, characterized in that The low-reflection film layer includes a low-reflection chromium film.

4. The production method according to claim 1 or 3, characterized in that: The reflectivity of the low-reflection film layer at 850nm is ≤2%.

5. The production method according to claim 3, characterized in that: The low-reflection chrome film includes a stacked Cr film and a CrO film.

6. The manufacturing method according to claim 5, characterized in that: The thickness of the Cr film and the CrO film are both 70 nm.

7. The production method according to claim 1, characterized in that: The photolithography process includes: coating photoresist on the surface of the low-reflection film layer, and then sequentially performing exposure, development, wet etching and removing the photoresist.

8. The production method according to claim 1, characterized in that: The line accuracy of the high-precision reflective metal code disk is ±1 μm, the inner and outer diameter size accuracy is ±5 μm, and the concentricity accuracy of the pattern and the inner and outer circles is within 5 μm.

9. The production method according to claim 1, characterized in that: The wet etching adopts stainless steel etching liquid; the stainless steel etching liquid is a mixture of ferric chloride solution and concentrated hydrochloric acid.

10. The manufacturing method according to claim 9, characterized in that: The concentration of the ferric chloride solution is 3 mol / L; the mass fraction of the concentrated hydrochloric acid is 36%; and the volume ratio of the ferric chloride solution to the concentrated hydrochloric acid is 97:3.

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