Particulate filter and method for manufacturing particulate filter

Abstract

To provide a filter for capturing fine particles having such a configuration as to be manufactured using a laser processing technique.SOLUTION: A filter for capturing fine particles has a transparent body having a first surface and a second surface and a thickness of 50 μm or more, and a plurality of through holes penetrating to the second surface from the first surface of the body, wherein when a position with a depth of 10 μm from the second surface is defined as a reference depth DS, in each of the through holes, a minimum cross section dimension at the reference depth DS is represented by φP, and a minimum cross section dimension between the reference depth DS and the second surface is represented by φP, φQ≤0.6 μm and φQ / φP≤0.5, are satisfied in the filter for capturing fine particles.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a particulate filter. [Background technology]

[0002] There is a need for particulate filters that can adequately capture foreign matter contained in a solution in many fields, such as medical facilities, pharmaceutical manufacturing plants, and high-purity clean rooms. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. WO2010 / 087483 Summary of the Invention [Problem to be solved by the invention]

[0004] One possible configuration of a filter for trapping fine particles is to provide minute through-holes in a part of the solution flow path of the filter, and trap the fine particles in the through-holes.

[0005] In addition, when mass-producing such particulate filters, it is possible to use laser processing technology, because the laser processing technology can rapidly form a large number of through holes with high dimensional accuracy in the workpiece (for example, Patent Document 1).

[0006] However, in order to reliably capture particles, it is necessary to form extremely fine through-holes (fine through-holes) of, for example, about 0.6 μm or less in a particulate filter. However, in general, the diameter of holes formed in a workpiece having a thickness of 50 μm or more using laser processing technology is limited to about 2 μm. For this reason, it is not easy to form the above-mentioned through-holes for capturing particles with high precision.

[0007] In particular, in a particulate filter, it may be necessary to form a large number of through holes, for example, 1,000 or more, in an inspection area of ​​1 mm x 1 mm. However, it is extremely difficult to form a large number of through holes with a diameter of less than 2 μm in such a small inspection area by using laser processing technology.

[0008] Due to this background, there have been almost no examples of manufacturing particulate filters using laser processing technology. However, if it were possible to manufacture particulate filters using laser processing technology, it would be preferable in terms of quality and manufacturing costs.

[0009] The present invention has been made in view of the above background, and has an object to provide a particulate filter having a configuration that can be manufactured using laser processing technology, and a method for manufacturing such a particulate filter. [Means for solving the problem]

[0010] The present invention provides a particulate filter, comprising: a transparent body having a first surface and a second surface and a thickness of 50 μm or more; a plurality of through holes extending from the first surface to the second surface of the body; having The position at a depth of 10 μm from the second surface is defined as the reference depth D S stipulates, In each through hole, the reference depth D S The minimum cross-sectional dimension at P The reference depth D S and the second surface, the minimum cross-sectional dimension is φ Q When φ Q ≦0.6 μm, φ Q / φ P ≦0.5.

[0011] The present invention also provides a method for producing a particulate filter, comprising the steps of: (I) providing a transparent substrate having a first surface and a second surface opposed to each other; (II) irradiating the first surface of the substrate with laser light to form a plurality of substrate through-holes penetrating the substrate from the first surface to the second surface; (III) providing a coating layer on the second surface of the substrate to form a plurality of through holes through the substrate and the coating layer; A method of manufacturing is provided, comprising: Effect of the Invention

[0012] The present invention can provide a particulate filter having a configuration that can be manufactured by utilizing laser processing technology. Another object of the present invention is to provide a method for manufacturing such a particulate filter. [Brief description of the drawings]

[0013] [Figure 1] 1 is a top view showing a schematic diagram of a particulate filter according to an embodiment of the present invention; [Diagram 2] 2 is a diagram showing an example of a cross section of an inspection region of the particulate filter according to the embodiment of the present invention shown in FIG. 1. FIG. [Diagram 3] FIG. 4 is a schematic diagram showing another cross section of a substrate through-hole in a substrate. [Figure 4] FIG. 2 is a diagram showing an example of a flow of a method for manufacturing a particulate filter according to an embodiment of the present invention. [Diagram 5] 1A to 1C are diagrams illustrating a process for producing a particulate filter according to an embodiment of the present invention. [Figure 6] 1A to 1C are diagrams illustrating a process for producing a particulate filter according to an embodiment of the present invention. [Figure 7] 1A to 1C are diagrams illustrating a process for producing a particulate filter according to an embodiment of the present invention. [Figure 8] 1A to 1C are diagrams illustrating a process for producing a particulate filter according to an embodiment of the present invention. [Figure 9] 1 is a photograph showing an example of a cross section of a through hole formed in a sample according to an example. [Figure 10] 13 is a photograph showing an example of a cross section of a through hole formed in a sample according to another embodiment. [Figure 11] 13 is a photograph showing an example of a cross section of a through hole formed in a sample according to yet another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, one embodiment of the present invention will be described.

[0015] In one embodiment of the present invention, there is provided a particulate filter comprising: a transparent body having a first surface and a second surface and a thickness of 50 μm or more; a plurality of through holes extending from the first surface to the second surface of the body; having The position at a depth of 10 μm from the second surface is defined as the reference depth D S stipulates, In each through hole, the reference depth D S The minimum cross-sectional dimension at P The reference depth D S and the second surface, the minimum cross-sectional dimension is φ Q When φ Q ≦0.6 μm, φ Q / φ P ≦0.5.

[0016] As mentioned above, the diameter of holes formed in a workpiece having a thickness of 50 μm or more by laser processing technology is limited to about 2 μm, and it is not easy to form finer holes with high precision. In particular, it is extremely difficult to mass-form through holes with a diameter of less than 2 μm in a minute inspection area by using laser processing technology.

[0017] In this regard, the particulate filter according to one embodiment of the present invention has the above-mentioned configuration. Although the particulate filter having such a configuration has a thickness of 50 μm or more, as will be described in detail later, it can be manufactured by utilizing laser processing technology.

[0018] Thus, in one embodiment of the present invention, particulate filters can be manufactured with high quality and low manufacturing costs.

[0019] (Particulate filter according to one embodiment of the present invention) Hereinafter, an embodiment of the present invention will be described in more detail with reference to the drawings.

[0020] 1 and 2 are schematic diagrams showing an example of the configuration of a particulate filter according to an embodiment of the present invention. Fig. 1 shows a top view of a particulate filter according to an embodiment of the present invention (hereinafter, referred to as a "first filter").

[0021] 1, the first filter 100 has a transparent body 110. The body 110 has a first surface 112 and a second surface 114. An inspection region 120 is disposed in the body 110.

[0022] 1, first filter 100 has a substantially circular shape when viewed from above. However, the shape of first filter 100 is not particularly limited, and may be, for example, an ellipse, a triangle, a rectangle, or a polygon having pentagons or more sides.

[0023] 1, the inspection region 120 is arranged in a substantially square shape in the substantially center of the main body 110 in a top view. However, this is merely one example. The inspection region 120 may be arranged in a non-center portion of the main body 110. The inspection region 120 may be arranged in a non-square shape, for example, a circle, an ellipse, a rectangle, or a polygon having pentagons or more sides.

[0024] Furthermore, the number of inspection regions 120 is not necessarily limited to one, and the inspection regions 120 may be provided in a plurality of locations on the main body 110.

[0025] 1, the inspection region 120 is clearly indicated by a rectangular frame. However, it should be noted that in the first filter 100, there are often cases where the boundary between the inspection region 120 and the non-inspection region cannot be clearly identified by visual inspection.

[0026] 1 shows an enlarged view of a part of the inspection area 120. As shown in this frame, a large number of through-holes 122 are formed in the inspection area 120.

[0027] The density of the through-holes 122 in the inspection area 120 is not particularly limited, but may be, for example, 100 pieces / mm 2 That's all.

[0028] There is no particular limitation on the form of the two-dimensional arrangement of the through-holes 122. The through-holes 122 may be arranged regularly or randomly.

[0029] Furthermore, when the through holes 122 are regularly arranged, the arrangement and pitch are not particularly limited. For example, the through holes 122 may be regularly arranged vertically and horizontally as shown in Fig. 1. The pitch may be, for example, in the range of 10 µm to 100 µm.

[0030] 2 is a schematic diagram showing an example of a cross section of the inspection region 120 of the main body 110. In FIG. 2, a cross section along the longitudinal central axis of a plurality of through-holes 122 is shown.

[0031] 2, the main body 110 has a substrate 140 and a coating layer 150 formed on one surface of the substrate 140. A first surface 112 of the main body 110 corresponds to the surface of the substrate 140 on which the coating layer 150 is not provided, and a second surface 114 corresponds to the surface of the coating layer.

[0032] In Figure 2, dashed line Di represents the boundary between the substrate 140 and the coating layer 150. However, in reality, this boundary D i However, there are often cases where the purpose of the study is unclear.

[0033] The body 110 includes a number of through holes 122. Each through hole 122 has a first opening 125 on the first surface 112 side of the body 110 and a second opening 127 on the second surface 114.

[0034] Each through hole 122 is formed by penetrating both the substrate 140 and the coating layer 150. Therefore, a first opening 125 of the through hole 122 is an opening on the substrate 140 side, and a second opening 127 is an opening on the coating layer 150 side.

[0035] In each through-hole 122, the portion on the substrate 140 side is particularly referred to as a "substrate through-hole 132a," and the portion on the coating layer 150 side is particularly referred to as a "coating layer through-hole 132b."

[0036] In the example shown in FIG. 2, in each through hole 122, the substrate through hole 132a has a tapered shape, and the first opening 125 is i The "minimum cross-sectional dimension" decreases monotonically until

[0037] Here, the "minimum cross-sectional dimension (of the through hole)" refers to the smallest distance between opposing side walls in a cross section passing through the central longitudinal axis of the through hole 122. Therefore, when the cross section of the through hole is circular, the "minimum cross-sectional dimension" represents the diameter, and when it is elliptical, the "minimum cross-sectional dimension" represents the dimension of the minor axis.

[0038] To be precise, the first opening 125 and the second opening 127 are not "cross-sections of through holes." However, in this application, the term "minimum cross-sectional dimension" is used to describe the dimensions of these openings 125 and 127.

[0039] 2, the taper angle θ of substrate through hole 132a is, for example, in the range of 65° to 89°. Here, the taper angle θ of substrate through hole 132a is represented by the angle between the normal to first surface 112 and the sidewall of substrate through hole 132a.

[0040] Referring again to FIG. 2, the coating layer through-hole 132b of the through-hole 122 has a more complex cross-sectional shape than the substrate through-hole 132a.

[0041] For example, in the example shown in FIG. 2, the coating layer through-hole 132b is located at the boundary D i to the second surface 114 (wherein the boundary D i In other words, the minimum cross-sectional dimension of the narrowed portion 154 is set to φ Q In this case, φ Q indicates the smallest minimum cross-sectional dimension among the through holes 122.

[0042] Here, in each through hole 122, a position at a depth of 10 μm from the second surface 114 of the main body 110 is referred to as a “reference depth”, and D S As shown in Figure 2, the reference depth D S is the boundary D i The reference depth D is located farther from the second surface 114 of the body 110 than the reference depth D S The minimum cross-sectional dimension of the through hole 122 at P It is expressed as:

[0043] In the first filter 100, the minimum cross-sectional dimension φ P and φ Q When using the above, each through hole 122 φ Q ≦0.6 μm, and φ Q / φ P ≦0.5 It has the characteristic of satisfying the following.

[0044] In particular, φ Q / φ P It may be ≦0.4.

[0045] The first filter 100 has a minimum cross-sectional dimension φ that is difficult to form by a general laser processing method. Q Each through hole 122 has a narrowed portion 154 that meets the requirement of ≦0.6 μm inside (or on the second surface 114 ).

[0046] Therefore, the first filter 100 can be used as a filter that captures fine particles having a particle size of, for example, more than about 0.6 μm.

[0047] Furthermore, in the first filter 100, the portion of the base material through hole 132a can be formed using a general laser processing technique. With the laser processing technique, base material through holes 132a of the same shape can be formed with high accuracy. Therefore, the first filter 100 can be manufactured with high quality and low cost.

[0048] Furthermore, in the first filter 100, the depth position of the narrowed portion 154 in each through hole 122 is set to be a position between the boundary D i (However, the boundary D i In this case, it becomes possible to capture particles at approximately the same depth position in any of the through-holes 122, which makes it easy to detect the particles.

[0049] (Parts of a particulate filter according to an embodiment of the present invention) Next, each part of the particulate filter according to one embodiment of the present invention will be described in more detail.

[0050] For the sake of clarity, each part of the particulate filter according to one embodiment of the present invention will be described using the first filter 100 as an example. Therefore, the reference symbols shown in Figures 1 and 2 will be used to represent each part.

[0051] (Main body 110) 1, the main body 110 has a substantially circular shape when viewed from above. However, the shape of the main body 110 is not particularly limited, and may be, for example, an ellipse, a triangle, a rectangle, or a polygon with pentagons or more sides.

[0052] The main body 110 is made of a transparent material. Here, "transparent" means that the average transmittance in the wavelength range of 360 nm to 830 nm is 80% or more.

[0053] Therefore, when the first filter 100 is used, the particles can be detected by common optical techniques such as infrared spectroscopy, Raman spectroscopy, optical microscopy, and fluorescence microscopy.

[0054] The thickness of the main body 110 is 50 μm or more, and preferably 60 μm or more. There is no particular upper limit to the thickness of the main body 110, but the thickness of the main body 110 may be, for example, 1 mm or less.

[0055] When the minimum cross-sectional dimension of first opening 125 of main body 110 is taken as φ1, φ1 preferably satisfies 5 μm≦φ1≦50 μm.

[0056] Furthermore, when the minimum cross-sectional dimension of second opening 127 of main body 110 is φ2, φ1 preferably satisfies 0.2 μm≦φ2≦5 μm.

[0057] In addition, the minimum cross-sectional dimension φ of the narrowed portion 154 Q is preferably 0.2 μm or more.

[0058] As mentioned above, it is difficult to form through holes with a minimum cross-sectional dimension of 0.6 μm or less using laser processing technology alone.

[0059] However, the body 110 has a substrate 140 and a coating layer 150. Thus, in the first filter 100, the body 110 has a minimum cross-sectional dimension φ Q It is possible to form the through hole 122 having the narrowed portion 154 of 0.6 μm or less.

[0060] When the depth of the narrowed portion 154 from the second surface 114 is d, the narrowed portion 154 may be present in the range of 0≦d<5 μm. The narrowed portion 154 may be present on the second surface 114, but the narrowed portion 154 may be present on the boundary D i is in a different position than

[0061] The inspection area 120 of the main body 110 has a capacity of 100 pieces / mm 2 It is preferable that the through holes 122 are formed at a density of 500 pcs / mm or more. 2 ~15,000 pieces / mm 2 It is more preferable that the range is .

[0062] (Base material 140) There is no particular limitation on the type of the base material 140 that constitutes a part of the main body 110. The base material 140 may be made of a transparent material such as glass or resin.

[0063] The thickness of the base material 140 is preferably 50 μm or more. The thickness of the base material 140 may be, for example, 1 mm or less.

[0064] 2 is merely an example, and the substrate through hole 132a may have a different cross section. For example, the substrate through hole 132a may have a cross section as shown in FIG.

[0065] Another cross section of the substrate through-hole 132a is shown in schematic form in Fig. 3. Note that in Fig. 3, only the substrate 140 portion of the main body 110 is shown, and the coating layer 150 is not shown.

[0066] 3, the substrate through hole 132a has a substrate narrowing portion 148 inside the substrate 140. The substrate through hole 132a has a shape such that the "minimum cross-sectional dimension" increases from the substrate narrowing portion 148 toward each surface of the substrate 140.

[0067] Substrate through-holes 132a having such a cross-sectional shape are likely to be produced when substrate 140 having fine through-holes is subjected to a wet etching process, as described below.

[0068] Thus, it should be noted that in one embodiment of the present invention, the cross-sectional shape of substrate through-hole 132a is not particularly limited.

[0069] (Coating layer 150) The type of coating layer 150 is not particularly limited as long as it is transparent.

[0070] The material of the coating layer 150 is not particularly limited as long as it is transparent, but materials mainly made of silica, alumina, magnesium oxide, and magnesium fluoride are preferred because they have a low refractive index and can maintain a high transmittance. Materials mainly made of silica, hafnium oxide, tantalum oxide, and magnesium fluoride are also preferred because they have a small extinction coefficient in the ultraviolet range.

[0071] The coating layer 150 is preferably made of silica or magnesium fluoride, which has a low refractive index and a low extinction coefficient over a wide wavelength range.

[0072] The thickness of the coating layer 150 is not particularly limited, but is preferably in the range of, for example, 0.1 μm to 5 μm.

[0073] The thickness of the coating layer is 10 μm or less at most. i The depth from the second surface 114 to the reference depth D S is equal to or less than the distance to.

[0074] An embodiment of the present invention has been described above by taking the first filter 100 as an example.

[0075] However, the above description is merely an example, and a particulate filter according to an embodiment of the present invention may have other configurations.

[0076] For example, in the example shown in FIG. 2, the coating layer through hole 132b of the first filter 100 has a minimum cross-sectional dimension that gradually increases from the constriction 154 toward the second surface 114. However, in contrast, the coating layer through hole 132b has a minimum cross-sectional dimension that gradually increases from the constriction 154 toward the second surface 114. i From the second surface 114 to the second surface 114, the minimum cross-sectional dimension of the second opening 127 may be gradually decreased. In this case, the minimum cross-sectional dimension of the second opening 127 may be φ Q It becomes.

[0077] Furthermore, for example, the coating layer through-hole 132b may have a straight portion that extends parallel to the thickness direction of the coating layer.

[0078] That is, in the particulate filter according to one embodiment of the present invention, the substrate through-holes 132a and the coating layer through-holes 132b may have any shape as long as they have the above-mentioned characteristics.

[0079] Furthermore, in the above description, the particulate filter according to the embodiment of the present invention has been described using the case where the through-holes are formed in the transparent body as an example, but the particulate filter according to the embodiment of the present invention may have slits instead of through-holes.

[0080] (Method of manufacturing a particulate filter according to one embodiment of the present invention) Next, an example of a method for manufacturing the particulate filter according to one embodiment of the present invention will be described with reference to FIGS.

[0081] FIG. 4 shows a schematic flow of a method for producing a particulate filter according to one embodiment of the present invention (hereinafter referred to as a "first method").

[0082] As shown in FIG. 4, the first method is: (1) preparing a transparent substrate having a first surface and a second surface opposed to each other (step S110); (2) irradiating the first surface of the substrate with laser light to form a plurality of substrate through-holes penetrating the substrate from the first surface to the second surface (step S120); (3) providing a coating layer on the second surface of the substrate and forming a plurality of through holes penetrating the substrate and the coating layer (step S130); has.

[0083] Each step will be described below with reference to Figures 5 to 8. Note that the manufacturing method will be described below with reference to the first filter shown in Figures 1 and 2 as an example of the particulate filter. Therefore, when referring to each part of the particulate filter, the reference symbols shown in Figures 1 and 2 will be used.

[0084] (Step S110) First, a transparent substrate 140 is prepared.

[0085] 5 shows a perspective view of a substrate 140. The substrate 140 has a first surface 142 and a second surface 144.

[0086] 5, the first surface 142 and the second surface 144 have a substantially circular shape. However, the shapes of the first surface 142 and the second surface 144 are not particularly limited. The first surface 142 and the second surface 144 may have a shape such as an ellipse, a triangle, a rectangle, or a polygon having pentagons or more sides.

[0087] The substrate 140 may be made of any material as long as it is transparent. The substrate 140 may be made of, for example, glass or resin.

[0088] The thickness of the substrate 140 is preferably 50 μm or more.

[0089] Note that, before the next step S120, an absorbing material may be provided on the first surface 142 of the base material 140. When an absorbing material is provided, the energy of the laser light irradiated to the base material 140 can be absorbed more efficiently. Therefore, in the next step S120, it becomes possible to perform high-quality laser processing with lower energy.

[0090] However, the installation of the absorbent material 220 is optional.

[0091] FIG. 6 shows a schematic diagram of an absorbent material 220 provided on a first surface 142 of a substrate 140. In FIG.

[0092] The material of the absorbing layer 220 is not particularly limited as long as it has the function of absorbing at least a part of the energy of the pulsed laser used. The absorbing layer 110 may be, for example, a synthetic resin ink or a pigment including carbon black or the like.

[0093] (Process S120) Next, laser light is irradiated from the side of first surface 142 of substrate 140 to form substrate through-hole 132a.

[0094] The type of laser light is not particularly limited, but a UV laser is preferable.

[0095] The laser light may be, for example, a short pulse laser.

[0096] 7 is a schematic cross-sectional view of a substrate 140 in which a substrate through-hole 132a is formed. Note that the absorbent material 220 is omitted in FIG.

[0097] A plurality of substrate through-holes 132a extending from the first surface 142 to the second surface 144 are formed in the substrate 140 by the irradiation of the laser light.

[0098] As shown in FIG. 7, substrate through-hole 132a formed by laser light irradiation tends to have a cross-sectional shape that tapers from first surface 142 to second surface 144.

[0099] The taper angle θ1 is in the range of 65° to 89°, for example.

[0100] Each substrate through-hole 132 a has a first opening 226 a on a first surface 142 of the substrate 140 and a second opening 226 b on a second surface 144 .

[0101] The minimum cross-sectional dimension of the first opening 226a is, for example, in the range of 4 μm to 30 μm, and preferably in the range of 4 μm to 15 μm.

[0102] The minimum cross-sectional dimension of the second opening 226b is, for example, in the range of 2 μm to 10 μm, and preferably in the range of 2 μm to 5 μm.

[0103] The number of the base through holes 132a to be formed is not particularly limited. When used in a particulate filter, the density of the base through holes 132a is, for example, 100 holes / mm 2 More than 500 pieces / mm 2 ~15,000 pieces / mm 2 It is preferable that the range is 100%.

[0104] After the substrate through-hole 132a is formed, the substrate 140 may be subjected to a wet etching process.

[0105] By carrying out wet etching, the absorbing material 220 and debris generated during laser processing can be removed.

[0106] For example, if the substrate 140 is glass, the wet etching process may be performed in a hydrofluoric acid solution.

[0107] When wet etching is performed, the shape of the substrate through hole 132a may often change. For example, the first opening 226a of the substrate through hole 132a may change in the range of 4.1 μm to 30.1 μm. The minimum cross-sectional dimension of the second opening 226b may change in the range of 2.1 μm to 10.1 μm.

[0108] Furthermore, the cross-sectional shape of substrate through-hole 132a can also be changed in two main ways.

[0109] In the first mode, the cross-sectional dimension of the substrate through-hole 132a is expanded while the taper angle θ1 is maintained.

[0110] In the second embodiment, a cross-sectional shape as shown in Fig. 3 is obtained. That is, the substrate through-hole 132a is shaped to have a substrate narrowing portion 148 between the first surface 142 and the second surface 144.

[0111] The cross-sectional shape shown in FIG. 3 is likely to occur when the thickness of the base material 140 is large and / or when the dimensions of the first opening 226a and the second opening 226b are small.

[0112] That is, if the dimensions of the first opening 226a and the second opening 226b are small, it becomes difficult for the etching solution to sufficiently penetrate into the inside of the substrate through hole 132a. In that case, the portions close to both surfaces 142, 144 of the substrate through hole 132a are selectively etched, and the substrate through hole 132a having the substrate narrowed portion 148 as shown in FIG. 3 is formed.

[0113] The same applies when the thickness of the base material 140 is large.

[0114] In this way, the shape of the substrate through hole 132a may change before and after the wet etching process. However, in the present application, the substrate through hole 132a after the wet etching process is referred to as "substrate through hole 132a" as it is.

[0115] Furthermore, when the first surface 142 and the second surface 144 of the base material 140 are etched by wet etching, different surfaces (new surfaces) are exposed.

[0116] However, the amount of etching of the first surface 142 and the second surface 144 of the substrate 140 is small. Therefore, the exposed surfaces of the substrate 140 after the wet etching process will still be referred to as the "first surface 142" and the "second surface 144."

[0117] (Step S130) A coating layer is then applied to the second surface 144 of the substrate 140 .

[0118] This step is performed to adjust the size and shape of the tip of the substrate through-hole 132a.

[0119] The method for applying the coating layer is not particularly limited.

[0120] The coating layer may be disposed on the second surface 144 of the substrate 140 by, for example, sputtering or vapor deposition.

[0121] In the sputtering method or vapor deposition method, the possibility that the substrate through-holes 132a are blocked can be significantly reduced, and a coating layer having coating layer through-holes 132b communicating with the substrate through-holes 132a can be appropriately formed.

[0122] As described above, the type of the coating layer is not particularly limited. The coating layer may be made of, for example, silica, alumina, MgO, MgF, Ta2O5, or the like.

[0123] The thickness of the coating layer is at most 10 μm, for example, in the range of 0.1 μm to 5 μm.

[0124] 8 is a schematic diagram showing a state after the coating layer 150 is provided on the second surface 144 of the substrate 140. In FIG. 8, the dashed line L1 indicates the boundary between the substrate 140 and the coating layer 150, i.e., the boundary D i where the boundary D i are often difficult to recognize with light and electron microscopes.

[0125] 8, the coating layer 150 is formed to have coating layer through-holes 132b corresponding to the substrate through-holes 132a. In other words, the coating layer through-holes 132b of the coating layer 150 are formed to extend the substrate through-holes 132a formed in the substrate 140 to the surface 152 of the coating layer 150.

[0126] This allows the formation of through holes 122 that penetrate from the first surface 142 of the substrate 140 to the surface 152 of the coating layer 150 .

[0127] The through-hole 122 has a third opening 240 c on the side of the surface 152 of the coating layer 150 .

[0128] The minimum cross-sectional dimension φ2 of the third opening 240c is in the range of 0.2 μm to 5 μm.

[0129] Thus, in the first method, a plurality of through holes 122 can be formed from the first surface 142 of the substrate 140 to the surface 152 of the coating layer 150 .

[0130] These through holes 122 have a minimum cross-sectional dimension φ P and φ Q When using φ Q ≦0.6 μm, and φ Q / φ P ≦0.5 Meet the following.

[0131] Here, φ P is the minimum cross-sectional dimension of the through hole 122 at the reference depth Ds (not shown in FIG. 8).

[0132] In addition, the through hole 122 has a minimum cross-sectional dimension φ Q The position where φ2=φ may be the third opening 240c. Q It is.

[0133] In the first method, the minimum cross-sectional dimension φ Q A constriction 154 meeting ≦0.6 μm may be formed within each through-hole 122 (or on the surface 152 of the coating layer 150 ).

[0134] Therefore, the filter manufactured by the first method can be used as a filter for capturing fine particles having a particle size of, for example, more than about 0.6 μm.

[0135] In the first method, the base through hole 132a can be formed by using a general laser processing technique, and therefore the first method can produce a high-quality, low-cost filter for trapping fine particles.

[0136] Furthermore, in the first method, in each through hole 122, the depth position of the narrowed portion 154 is set to a position from the surface 152 of the coating layer 150 to the boundary D i (However, the boundary D i In this case, it becomes possible to capture particles at approximately the same depth position in any of the through-holes 122, which makes it easy to detect the particles. EXAMPLES

[0137] Next, examples of the present invention will be described below. In the following description, examples 1 to 3 are examples, and example 11 is a comparative example.

[0138] (Example 1) The evaluation samples were prepared by the following method.

[0139] First, a base material having a first surface and a second surface opposed to each other was prepared. The base material was a glass substrate having a thickness of 200 μm.

[0140] Next, a laser beam was irradiated onto the first surface side of the substrate to form a plurality of through holes (substrate through holes). A pulsed laser was used as the laser beam.

[0141] Next, a coating layer was formed on the second surface of the substrate by sputtering. The coating layer was a silica layer with a thickness of 3.1 μm. After the coating, through holes were obtained that penetrated from the substrate to the coating layer.

[0142] As a result, an evaluation sample (hereinafter referred to as "Sample 1") was produced.

[0143] The minimum cross-sectional dimension φ1 of the first opening on the substrate side and the minimum cross-sectional dimension φ2 of the second opening on the coating side were measured for the through hole of Sample 1. The results were φ1 = 8.0 μm and φ2 = 3.4 μm.

[0144] (Example 2) An evaluation sample was prepared in the same manner as in Example 1. However, in this Example 2, the thickness of the coating layer was set to 4.3 μm.

[0145] The evaluation sample thus prepared is referred to as "Sample 2."

[0146] The minimum cross-sectional dimension φ1 of the first opening on the substrate side and the minimum cross-sectional dimension φ2 of the second opening on the coating side were measured for the through hole of Sample 2. The results were φ1 = 8.0 μm and φ2 = 2.7 μm.

[0147] (Example 3) An evaluation sample was prepared in the same manner as in Example 1. However, in this Example 3, the thickness of the coating layer was set to 4.9 μm.

[0148] The evaluation sample thus prepared is referred to as "Sample 3."

[0149] The minimum cross-sectional dimension φ1 of the first opening on the substrate side and the minimum cross-sectional dimension φ2 of the second opening on the coating side were measured for the through hole of Sample 3. The results were φ1=8.0 μm and φ2=2.8 μm.

[0150] (Example 11) A through hole was formed in a glass substrate and used as an evaluation sample in the same manner as in Example 1. That is, in Example 11, no silica layer coating was performed.

[0151] The obtained evaluation sample is referred to as "Sample 11."

[0152] The minimum cross-sectional dimension φ1 of the first opening on the substrate side and the minimum cross-sectional dimension φ2 of the second opening on the coating side were measured for the through hole of Sample 11. The results were φ1=8.0 μm and φ2=2.0 μm.

[0153] Table 1 below shows the preparation conditions for each sample.

[0154] [Table 1] (Cross-sectional evaluation) Each of the prepared samples was cut at a cross section passing through the longitudinal central axis of some of the through holes to prepare evaluation specimens. The following dimensions were measured using the evaluation specimens: Reference depth D S Minimum cross-sectional dimension φ of the through hole (10 μm from the surface of the coating layer) P , and Minimum cross-sectional dimension φ at the narrowed part of the through hole Q .

[0155] Here, the narrowed portion is defined as the depth position where the minimum cross-sectional dimension of the through hole is smallest.

[0156] The narrowed portion was located inside the coating layer except for Sample 11. On the other hand, in Sample 11, the narrowed portion was located on the second surface of the substrate.

[0157] 9 to 11 show examples of cross sections of through holes on the coating layer side in Samples 1 to 3, respectively.

[0158] It should be noted that in Figures 9 to 11, some parts look whitish due to light reflection, and such parts do not necessarily correspond to the outline of the through-hole. In particular, there is a region that looks sharp and white near the narrowed portion in the coating layer, but this is not the tip of the through-hole. In each figure, the through-hole has an opening on the surface of the coating layer.

[0159] Table 2 below shows a summary of the dimensions obtained for each evaluation sample.

[0160] [Table 2] From the measurement results, in Samples 1 to 3, the minimum cross-sectional dimension φ Q It was found that a narrowed area of ​​0.6 μm or less was formed.

[0161] In addition, in samples 1 to 3, the ratio φ Q / φ P was found to be less than 0.5. [Explanation of symbols]

[0162] 100 First Filter 110 Main unit 112 First surface of the body 114 Second surface of the body 120 Inspection Area 122 Through hole 125 First Opening 127 Second Opening 132a Base material through hole 132b Coating layer through hole 140 Base material 142 First surface of substrate 144 Second surface of substrate 148 Base material constriction 150 coating layers 152 Coating layer surface 154 Stenosis 220 Absorbent 226a First opening 226b Second opening 240c Third opening

Claims

1. A particulate filter comprising: a transparent body having a first surface and a second surface and a thickness of 50 μm or more; a plurality of through holes extending from the first surface to the second surface of the body; having The position at a depth of 10 μm from the second surface is defined as a reference depth D Ｓ stipulates, In each through hole, the reference depth D Ｓ The minimum cross-sectional dimension in Ｐ and the reference depth D Ｓ and the second surface, the minimum cross-sectional dimension is φ Ｑ When φ Ｑ ≦0.6 μm, and φ Ｑ / φ Ｐ ≦0.

5.

2. Said φ Ｑ 2. The particulate filter according to claim 1, wherein the particle diameter is 0.2 μm or more.

3. For each through hole, the minimum cross-sectional dimension at the first surface is φ １ When 5 μm≦φ １ 3. The particulate filter according to claim 1, wherein the particle size is ≦50 μm.

4. For each through hole, the minimum cross-sectional dimension at the second surface is φ ２ When 0.2μm≦φ ２ 4. The particulate filter according to claim 1, wherein the particle size is ≦5 μm.

5. The through hole is at the reference depth D from the first surface. Ｓ 5. A particulate filter according to claim 1, wherein the minimum cross-sectional dimension decreases monotonically until

6. The minimum cross-sectional dimension φ Ｑ 6. The particulate filter according to claim 1, wherein the position at which the above-mentioned is obtained is located at a depth from the second surface in the range of 0 to less than 5 [mu]m.

7. The body has a substrate and a coating layer; 7. The particulate filter according to claim 1, wherein the second surface is a surface of the coating layer.

8. 8. The particulate filter according to claim 7, wherein the substrate is made of glass or resin.

9. 9. The particulate filter according to claim 7, wherein the coating layer has a thickness in the range of 1 μm to 5 μm.

10. A method for manufacturing a particulate filter, comprising the steps of: (I) providing a transparent substrate having a first surface and a second surface opposed to each other; (II) irradiating the first surface of the substrate with laser light to form a plurality of substrate through-holes penetrating the substrate from the first surface to the second surface; (III) providing a coating layer on the second surface of the substrate to form a plurality of through holes through the substrate and the coating layer; having A position at a depth of 10 μm from the surface of the coating layer is defined as a reference depth D S , In each through hole, when the minimum cross-sectional dimension at the reference depth D S is φ P , the minimum cross-sectional dimension at the surface of the coating layer is φ 2 , and the minimum cross-sectional dimension between the reference depth D S and the surface of the coating layer is φ Q , A manufacturing method wherein φ Q ≦0.6 μm and φ Q / φ P ≦0.

5.

11. Before the step (II), providing an absorbent layer on the first surface of the substrate; The method of claim 10, comprising:

12. After the step (II), wet etching the substrate The method according to claim 10 or 11, comprising:

13. The substrate through-holes are 100 / mm ２ The manufacturing method according to claim 10 , wherein the particles are arranged at a density of at least 100 nm.

14. The method according to claim 10 , wherein the substrate has a thickness of 50 μm or more.

15. The method according to claim 10 , wherein the substrate is made of glass or resin.

16. The method according to any one of claims 10 to 15, wherein the coating layer has a thickness in the range of 1 μm to 5 μm.

Images