Manufacturing method of taper hole array metal filter screen and metal filter screen thereof

Abstract

The invention provides a manufacturing method of a taper hole array metal filter screen and the metal filter screen thereof.The taper holes of the metal filter screen are of a trapezoidal circular truncated cone through hole structure, and the taper of the taper holes of the metal filter screen is larger than 15 DEG C. The taper of the taper hole array metal filter screen manufactured through the method is large enough; and the taper, the aperture and the thickness of the taper hole array metal filter screen are controllable, so that the use scene of the metal filter screen is greatly widened.

Description

Technical Field

[0001] The invention relates to the field of advanced manufacturing, and in particular to a manufacturing method of a tapered hole array metal filter and the metal filter. Background Art

[0002] With the development of industrial technology, more and more microporous filters are designed into special shapes to achieve certain functions, such as conical through holes. Compared with straight hole filters, the design of conical hole filters has the advantages of larger filtration area, good self-cleaning effect and small flow resistance, which can ensure the balance of filtration effect and flow during use. For example, when the conical hole is used for screening and filtration of cells or bacteria, it is more conducive to the aggregation of target cells; for example, the substrate of the field emission cathode microcone array also requires conical holes with upper and lower apertures of 10-15μm; conical microelectrodes are suitable for processing conical micropores, used to manufacture micronozzles for inkjet printers, etc. In some application scenarios, the conical hole needs to have a large enough taper to meet the needs of the application.

[0003] Traditional methods for processing micro-holes include punching, laser micro-machining, electron beam drilling, and electro-spark technology. Each of the above methods has its own advantages and disadvantages, but they cannot process metal filters with a high aspect ratio, and more importantly, they cannot meet the needs of processing tapered through holes. Although there have been experimental studies on the use of lasers to process tapered micro-holes in recent years, the size of each prepared tapered hole is different, and it is impossible to accurately control the size of each micro-hole to be consistent when punching. In addition, the taper of the tapered hole is small, and the consistency of the taper size of the tapered hole is not easy to control, which limits the application scope of metal filters. At present, laser micro-machining, electron beam drilling, and electro-spark machining cannot produce array tapered holes with good quality consistency and a large enough taper.

[0004] Therefore, how to manufacture a metal filter mesh with a tapered hole array having a sufficiently large taper, and control the uniformity, consistency and stability of the micropores, while being suitable for mass production is a technical problem that urgently needs to be solved in this technical field. Summary of the invention

[0005] To this end, the present invention provides a method for manufacturing a metal filter with a conical hole array, wherein the conical holes of the metal filter are through-hole structures of a trapezoidal truncated cone, the conical hole taper of the metal filter is greater than 15, and the conical hole taper of the metal filter is defined as the ratio between the difference between the long base of the trapezoidal truncated cone of the conical hole and the short upper side of the trapezoidal truncated cone and the height of the trapezoidal truncated cone; the method comprises the following steps: step 1: a photolithography mask production step, in which the photolithography mask is produced according to the structural requirements of the metal filter; step 2: a conductive layer preparation step, in which a layer of metal conductive layer material is sputtered on a glass substrate or a silicon substrate; step 3: a truncated cone array glue structure preparation step, in which a photoresist is spin-coated on the substrate of the sputtered conductive layer by photolithography, and a mask is placed to expose the photoresist, and the exposure dose range is 350mJ / cm 2-450mJ / cm 2 , and then developing the exposed photoresist in a developer to obtain a truncated cone array glue structure, the developing time is 120-240 seconds, and the developing temperature is 35-45°C; step 4: conical hole electroforming step, electroforming the truncated cone array glue structure through an electroforming process, and peeling the electroformed metal micro-through hole structure from a glass substrate or a silicon substrate with a conductive layer to obtain a metal filter; and step 5: degumming step, degumming the obtained metal filter to obtain a conical hole array metal filter.

[0006] In one embodiment, the metal conductive layer is made of nickel or chromium.

[0007] In one embodiment, in step 3, in the step of preparing the truncated cone array resist structure, the photoresist is an AZ photoresist positive resist.

[0008] In one embodiment, in step 3, after development, the obtained truncated cone array glue is post-baked at a temperature of 100°C-130°C.

[0009] In one embodiment, in step 4, pulse electroforming is used when electroforming the truncated cone array glue structure.

[0010] In one embodiment, in step 5, a standard positive resist stripping solution is used to strip the metal filter.

[0011] In one embodiment, a metal filter screen manufactured by the above manufacturing method is provided.

[0012] The present invention provides a method for manufacturing a metal filter with a tapered hole array to overcome the problem that traditional straight holes cannot meet the increasingly wide range of application scenarios. By combining photolithography technology and electroforming technology, the exposure, development parameters, and post-baking parameters in the photolithography process are controlled to achieve the preparation of a metal filter with a tapered hole array with controllable taper, and a method for preparing a metal filter with a tapered hole array having a taper greater than 15° is provided.

[0013] The present invention provides a method for manufacturing a metal filter with a conical hole array and a metal filter thereof. By controlling the exposure and development parameters in the photolithography process, a truncated cone array film structure can be prepared. By only controlling the exposure dose and the development time, the formed truncated cone structure has a limited taper, and increasing the developer temperature can greatly increase the taper of the truncated cone film structure. However, after the temperature rises to 50°C, the truncated cone film structure will be washed away by the developer. Therefore, adding a post-baking step after development can further increase the taper. After the above-mentioned truncated cone array film structure is formed, a metal filter with a conical hole array can be prepared by precisely controlling the electroforming time. The present invention uses the exposure dose, development time, development temperature and increased post-baking in the photolithography process, and combines the electroforming process to achieve the preparation of a metal filter with a larger taper. The array distribution, pore size, pore gap, taper and thickness of the metal filter with a conical hole array prepared by the method of the present invention are controllable, which greatly expands the application scenarios of the metal filter. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0015] Figure 1 A schematic diagram of the steps of a method for manufacturing a tapered hole array metal filter according to an embodiment of the present invention;

[0016] Figure 2 A technical roadmap for manufacturing a tapered hole array metal filter according to an embodiment of the present invention;

[0017] Figure 3 This is a plan view of the holes on the hexagonal array conical micro-through hole array metal filter prepared in Example 1 of the present invention, taken under a scanning electron microscope;

[0018] Figure 4 This is a plan view of the holes of the hexagonal array conical micro-through hole array metal filter prepared in Example 1 of the present invention taken under a scanning electron microscope;

[0019] Figure 5 This is a plan view of the holes on the hexagonal array conical micro-through hole array metal filter prepared in Example 2 of the present invention, taken under a scanning electron microscope;

[0020] Figure 6 This is a plan view of the holes of the hexagonal array conical micro-through hole array metal filter prepared in Example 2 of the present invention taken under a scanning electron microscope;

[0021] Figure 7This is a plan view of the holes on the hexagonal array conical micro-through hole array metal filter prepared in Example 3 of the present invention, taken under a scanning electron microscope;

[0022] Figure 8 This is a plan view of the holes of the hexagonal array conical micro-through hole array metal filter prepared in Example 3 of the present invention, taken under a scanning electron microscope;

[0023] Fig. 9 This is a plan view of the holes on the hexagonal array conical micro-through hole array metal filter prepared in Example 4 of the present invention, taken under a scanning electron microscope;

[0024] Fig.10 This is a plan view of the holes under the hexagonal array conical micro-through hole array metal filter prepared in Example 4 of the present invention, taken under a scanning electron microscope. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the technical solutions in this application, the present invention will be further described below in conjunction with embodiments. Obviously, the described embodiments are only part of the embodiments of this application, rather than all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0026] Example 1

[0027] A conical hole array metal filter, consisting of a metal outer ring and a central microporous array mesh structure, the metal outer ring and the central microporous array mesh structure are both circular in shape as a whole, the mesh structure is located at the center of the filter and is concentric with the outer ring, the outer ring has a diameter of 25 mm, the mesh structure has a diameter of 10 mm, and the thickness is 10 μm.

[0028] A method for manufacturing a metal filter screen having a cone hole array, such as Figure 1 , 2 As shown, the following steps are included:

[0029] (1) Making a circular hexagonal array photolithography mask with an aperture of 13 μm and an aperture spacing of 20 μm;

[0030] (2) Preparation of the conductive layer: sputtering a layer of chromium with a thickness of 200 nm on the glass substrate;

[0031] (3) Prepare a truncated cone array glue structure, spin-coat AZ40XT-11D positive photoresist on the glass with sputtered chromium layer, place a mask to expose the photoresist, and use 250, 300, 350, 400, 450, 500 and 550 J / cm 2Different exposure doses; the exposed photoresist is developed in AZ 300MIF developer to obtain a truncated cone array structure, developed at room temperature 21°C, and the developer time is 2 minutes;

[0032] (4) Cone hole electroforming: The truncated cone array glue structure is electroformed by a pulse electroforming process, with a current of 2 A, a frequency of 5 Hz, a positive / negative duty cycle of 5%, and an electroforming time of 40 min. The electroformed metal micro-through hole structure is peeled off from the glass substrate with a chromium layer to obtain a metal filter;

[0033] (5) Degumming: the obtained metal filter is immersed in AZ 400T STRIPPER degumming liquid for 3 hours for degumming treatment to obtain a hexagonal array cone hole array metal filter.

[0034] The obtained conical hole metal filter was photographed, measured and analyzed through a microscope, such as Figure 3 and Figure 4 As shown, a metal filter with a conical hole array is obtained. The tapers of the metal filters with conical holes obtained with different exposure doses are shown in Table 1. The taper of the conical holes of the metal filter is defined as the ratio of the difference between the long base of the trapezoidal cone of the conical hole and the short upper side of the trapezoidal cone to the height of the trapezoidal cone.

[0035] Table 1

[0036]

[0037] Under the conditions of developing at room temperature of 21°C and developing time of 2 minutes, as shown in Table 1, the taper of the metal filter increases slightly with the change of exposure dose. The exposure dose is 250mJ / cm 2 It is impossible to develop and measure the taper of the result; at 300mJ / cm 2 When the structure is clear, 350mJ / cm 2 -450mJ / cm 2 Exposure dose range: the taper of the metal filter is in the range of 1.1-1.8°, 500mJ / cm 2 and 550mJ / cm 2 Although the taper of the metal filter has a slight increase, at 550mJ / cm 2 When the exposure dose is low, the outline of the metal filter structure is blurred.

[0038] Example 2

[0039] A conical hole array metal filter, consisting of a metal outer ring and a central microporous array mesh structure, the metal outer ring and the central microporous array mesh structure are both circular in shape as a whole, the mesh structure is located at the center of the filter and is concentric with the outer ring, the outer ring has a diameter of 25 mm, the mesh structure has a diameter of 10 mm, and the thickness is 10 μm.

[0040] A method for manufacturing a metal filter screen having a cone hole array, such as Figure 1 , 2 As shown, the following steps are included:

[0041] (1) Making a circular hexagonal array photolithography mask with an aperture of 13 μm and an aperture spacing of 20 μm;

[0042] (2) Preparation of the conductive layer: sputtering a layer of chromium with a thickness of 200 nm on the glass substrate;

[0043] (3) Preparation of the frustum array adhesive structure: Spin-coat AZ40XT-11D positive photoresist on the glass with sputtered chromium layer, place the mask to expose the photoresist, and the exposure dose is 400mJ / cm 2 ; The exposed photoresist was developed in AZ 300MIF developer to obtain a truncated cone array structure. At a temperature of 21°C, the developer time was modified to 90s, 120s, 180s, 240s, 300s and 360s;

[0044] (4) Cone hole electroforming: The truncated cone array glue structure is electroformed by a pulse electroforming process, with a current of 2A, a frequency of 5Hz, a positive / negative duty cycle of 5%, and an electroforming time of 40min. The electroformed metal micro-through hole structure is peeled off from the glass substrate with a chromium layer to obtain a metal filter;

[0045] (5) Degumming: the obtained metal filter is immersed in AZ 400T STRIPPER degumming liquid for 3 hours for degumming treatment to obtain a hexagonal array cone hole array metal filter.

[0046] The obtained conical hole metal filter was photographed, measured and analyzed through a microscope, such as Figure 5 and Figure 6 As shown, a conical hole array metal filter is obtained, and the taper of the conical hole metal filter obtained at different development times is shown in Table 2.

[0047] Table 2

[0048]

[0049] When the exposure dose is constant (400mJ / cm 2 ), developed at room temperature at 21°C, the structure could not be developed at 90 seconds, and the development time was gradually increased to 120, 180, 240, 300 and 360 seconds. As time increased, the taper became larger, and when the development time increased to 300s, the taper increased to 3°, but it fell off. At 360s, the structure fell off in a large area and the glue fell off, making it impossible to obtain a conical hole in the later electroforming. From the experimental results, it can be seen that a metal filter with a clear conical hole structure can be obtained in a development time of 120-240 seconds, and the taper gradually increases.

[0050] Example 3

[0051] A conical hole array metal filter, consisting of a metal outer ring and a central microporous array mesh structure, the metal outer ring and the central microporous array mesh structure are both circular in shape as a whole, the mesh structure is located at the center of the filter and is concentric with the outer ring, the outer ring has a diameter of 25 mm, the mesh structure has a diameter of 10 mm, and the thickness is 10 μm.

[0052] A method for manufacturing a metal filter screen having a cone hole array, such as Figure 1 , 2 As shown, the following steps are included:

[0053] (1) Making a circular hexagonal array photolithography mask with an aperture of 13 μm and an aperture spacing of 20 μm;

[0054] (2) Preparation of the conductive layer: sputtering a layer of chromium with a thickness of 200 nm on the glass substrate;

[0055] (3) Prepare a truncated cone array glue structure, spin-coat AZ40XT-11D positive photoresist on the glass with sputtered chromium layer, place a mask to expose the photoresist, and the exposure dose is 400mJ / cm 2 ; The exposed photoresist was developed in AZ 300MIF developer to obtain a truncated cone array structure, and the developer temperature was 21°C, 25°C, 35°C, 40°C, 45°C and 50°C for 4 minutes;

[0056] (4) Cone hole electroforming: The truncated cone array glue structure is electroformed by a pulse electroforming process, with a current of 2 A, a frequency of 5 Hz, a positive / negative duty cycle of 5%, and an electroforming time of 40 min. The electroformed metal micro-through hole structure is peeled off from the glass substrate with a chromium layer to obtain a metal filter;

[0057] (5) Degumming: the obtained metal filter is immersed in AZ 400T STRIPPER degumming liquid for 3 hours for degumming treatment to obtain a hexagonal array cone hole array metal filter.

[0058] The obtained conical hole metal filter was photographed, measured and analyzed through a microscope, such as Figure 7 and 8 , a conical hole array metal filter is obtained, and the taper of the conical hole metal filter obtained at different development times is shown in Table 3.

[0059] Table 3

[0060]

[0061] When the exposure dose is constant (400mJ / cm 2), the developing time was 4min, and the developing solution temperature was gradually increased from 21℃ to 25℃, 35℃, 40℃, 45℃ and 50℃. As the temperature increased, the taper became larger in turn, especially when the temperature was raised to 35℃, the taper of the conical hole metal filter increased significantly, from 4.5° at 25℃ to 15.2 degrees Celsius, but it fell off at 50℃. From the experimental results, it can be seen that when the developing temperature is in the range of 35-45℃, a conical hole metal filter with a clear structure of 15-25° can be prepared.

[0062] Example 4

[0063] A conical hole array metal filter, consisting of a metal outer ring and a central microporous array mesh structure, the metal outer ring and the central microporous array mesh structure are both circular in shape as a whole, the mesh structure is located at the center of the filter and is concentric with the outer ring, the outer ring has a diameter of 25 mm, the mesh structure has a diameter of 10 mm, and the thickness is 10 μm.

[0064] A method for manufacturing a metal filter screen having a cone hole array, such as Figure 1 , 2 As shown, the following steps are included:

[0065] (1) Making a circular hexagonal array photolithography mask with an aperture of 13 μm and an aperture spacing of 20 μm;

[0066] (2) Preparation of the conductive layer: sputtering a layer of chromium with a thickness of 200 nm on the glass substrate;

[0067] (3) Preparation of the frustum array adhesive structure: Spin-coat AZ40XT-11D positive photoresist on the glass with the sputtered chromium layer, place a mask to expose the photoresist, and the exposure dose is 400 mJ / cm 2 ; Develop the exposed photoresist in AZ 300MIF developer to obtain a truncated cone array glue structure, set the developer temperature to 45°C, and develop for 4 minutes; after development, post-bake the glue structure at 100°C, 105°C, 110°C, 120°C, 130°C, and 140°C for 2 minutes;

[0068] (4) Cone hole electroforming: The truncated cone array glue structure is electroformed by a pulse electroforming process, with a current of 2 A, a frequency of 5 Hz, a positive / negative duty cycle of 5%, and an electroforming time of 40 min. The electroformed metal micro-through hole structure is peeled off from the glass substrate with a chromium layer to obtain a metal filter;

[0069] (5) Degumming: the obtained metal filter is immersed in AZ 400T STRIPPER degumming liquid for 3 hours for degumming treatment to obtain a hexagonal array cone hole array metal filter.

[0070] The obtained conical hole metal filter was photographed, measured and analyzed through a microscope, such as Fig. 9 and 10 , a conical hole array metal filter is obtained, and the taper of the conical hole metal filter obtained by post-baking temperature is shown in Table 4.

[0071] Table 4

[0072]

[0073] When the developer temperature is 45°C and the development time is 4 minutes, a post-baking step is added after development, and the post-baking temperatures are 100°C, 105°C, 110°C, 120°C, 130°C and 140°C. Compared with the previous process without post-baking, increasing the post-baking temperature can significantly increase the taper of the conical hole metal filter; as the temperature increases, the taper becomes larger, and when it increases to 140°C, the structure is blurred and unclear. From the above experimental results, it can be seen that a post-baking temperature of 100-130°C can be used.

[0074] Those skilled in the art will also recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. Such equivalents are also intended to be encompassed by the appended claims.

Claims

1. A method for manufacturing a tapered hole array metal filter, characterized in that: The conical hole of the metal filter is a through hole structure of a trapezoidal truncated cone, the conical hole taper of the metal filter is greater than 15°, and the conical hole taper of the metal filter is defined as the ratio between the difference between the long base of the trapezoidal truncated cone of the conical hole and the short upper side of the trapezoidal truncated cone and the height of the trapezoidal truncated cone; The method comprises the following steps: Step 1: a photolithography mask production step, in which the photolithography mask is produced according to the requirements of the metal filter structure; Step 2: Conductive layer preparation step, sputtering a layer of metal conductive layer material on a glass substrate or a silicon substrate; Step 3: Preparation of the truncated cone array glue structure: Spin-coat the photoresist on the substrate of the sputtered conductive layer using photolithography, place the mask to expose the photoresist, and the exposure dose range is 350mJ / cm 2 -450mJ / cm 2 , then developing the exposed photoresist in a developer to obtain a truncated cone array resist structure, the developing time is 120-240 seconds, and the developing temperature is 35-45° C.; Step 4: a conical hole electroforming step, wherein the truncated cone array glue structure is electroformed by an electroforming process, and the electroformed metal micro-through hole structure is peeled off from a glass substrate or a silicon substrate with a conductive layer to obtain a metal filter; Step 5: a degumming step, in which the obtained metal filter is degummed to obtain a cone hole array metal filter.

2. The manufacturing method according to claim 1, characterized in that: In step 2, the metal conductive layer material is nickel or chromium.

3. The manufacturing method according to claim 1, characterized in that: In step 3, in the step of preparing the truncated cone array resin structure, the photoresist is an AZ photoresist positive resist.

4. The manufacturing method according to claim 1, characterized in that: In step 3, after development, the obtained truncated cone array glue is post-baked at a temperature of 100°C-130°C.

5. The manufacturing method according to claim 1, characterized in that: In step 4, a pulse electroforming method is used when electroforming the truncated cone array glue structure.

6. The manufacturing method according to claim 1, characterized in that: In step 5, the metal filter is debonded using a standard debonding solution for positive photoresist.

7. A metal filter screen with a tapered hole array, characterized in that: The invention is manufactured by the manufacturing method according to any one of claims 1 to 6.

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