JP2014125652A - Method for manufacturing metal filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a metal filter having no burrs on a hole inner wall of a through-hole and high process accuracy of a hole diameter of the through-hole.SOLUTION: The method for manufacturing a metal filter comprises: a deposition step of depositing a layer of a photosensitive resin on a copper substrate; an exposure step of exposing a predetermined part of the photosensitive resin layer; a development step of forming a resist pattern comprising a cured product of the photosensitive resin by developing the photosensitive resin; a first plating step of forming a first plating layer by subjecting the copper substrate with the resist pattern formed thereon to metal plating; a second plating step of forming a second plating layer by subjecting the copper substrate having the resist pattern and the first plating layer formed thereon to metal plating with a metal different from the metal of the first plating layer; a dissolution step of obtaining a structure composed of the resist pattern and the second plating layer by removing the copper substrate and the first plating layer by chemical dissolution; and a stripping step of obtaining the second plating layer by removing the resist pattern from the structure. The second plating layer serves as the metal filter.

Description

  The present invention relates to a method for producing a metal filter. More specifically, the present invention relates to a method for producing a metal filter that can efficiently capture circulating cancer cells in the blood.

  Cancer occupies the top cause of death in countries around the world, and more than 300,000 people die from cancer annually in Japan, and early detection and treatment thereof are desired. Most deaths due to cancer are due to recurrence of cancer metastasis. The recurrence of cancer metastasis occurs when cancer cells settle from the primary lesion via blood vessels or lymphatic vessels and infiltrate into the blood vessel wall of another organ tissue to form a micrometastasis. Such cancer cells circulating in the human body through blood vessels and lymphatic vessels are called circulating tumor cells (hereinafter referred to as “CTC” in some cases).

Blood contains many blood cell components such as red blood cells, white blood cells, and platelets, and the number is said to be 3.5 to ⁹ × 10 ^{9 in} 1 mL of blood. However, there are only a few CTCs in this. Therefore, in order to efficiently detect CTC from blood cell components, it is necessary to separate blood cell components, and it is very difficult to observe and measure CTC.

  However, cancer cells such as CTC are slightly larger in size than blood cells in blood, such as red blood cells, white blood cells, or platelets. Therefore, it has been studied to remove these blood cell components by applying a mechanical filtration method and concentrate cancer cells. It is conceivable to use a metal filter as a filter for performing such a mechanical filtration method. As a method for producing a metal filter, for example, a method of electroforming (electroforming) plating using photolithography is known (Patent Document 1).

JP 2011-163830 A

  For example, the metal filter is manufactured by electroforming plating as follows. First, a photosensitive resin composition is laminated on a substrate. Next, the photosensitive resin composition layer is exposed to actinic rays and developed to form a resist pattern. Subsequently, the substrate on which the resist pattern is formed is subjected to metal plating (electroforming plating). Thereafter, the substrate and the resist pattern are removed, and only the metal plating layer is obtained. This metal plating layer becomes a metal filter.

  The inventors have found that when a metal filter is manufactured by the above-described manufacturing method, burrs may occur on the inner wall of the through hole of the metal filter due to plating soaking.

  The process of generating burrs will be described in more detail with reference to the drawings. FIG. 1 is a schematic view showing a mechanism for generating burrs by the above manufacturing method. As shown in FIG. 1A, in the above manufacturing method, first, a resist pattern made of a cured product 3a of a photosensitive resin composition is formed on a substrate 8. Next, a metal plating layer 9 is formed on the substrate 8 on which the resist pattern is formed by electroforming plating. At this time, plating soaking 10 occurs between the substrate 8 and the cured product 3a of the photosensitive resin composition. Subsequently, as shown in FIG. 1B, the resist pattern composed of the substrate 8 and the cured product 3a of the photosensitive resin composition is removed, and the metal plating layer 9 is recovered. This metal plating layer 9 is a metal filter. A through hole 7 is formed in the metal filter. Here, the metal filter has burrs formed by plating soaking 10. FIG. 2A shows a photograph of a metal filter in which burrs are generated on the inner wall of the through hole, observed with a scanning electron microscope (SEM, Scanning Electron Microscope). The magnification of the SEM image was 1000 times.

  When such a burr | flash generate | occur | produces, the hole diameter of the through-hole of a filter may become smaller than a design value. And the capture precision of the component made into a capture | acquisition target may fall by the dispersion | variation in the hole diameter of such a through-hole. The burr may damage cells captured by the metal filter or cells that have passed through the metal filter. Therefore, it is necessary to remove the burrs.

  However, if a metal filter having burrs is immersed in a chemical solution and the burrs are dissolved and removed by heating and stirring the chemical solution, only the burrs cannot be dissolved, and the diameter of the through hole of the metal filter may be enlarged. is there. Further, due to unevenness in the removal and removal of burrs, the hole diameter of the through hole of the metal filter may vary, and the processing accuracy of the hole diameter may be reduced.

  Then, an object of this invention is to provide the manufacturing method of a metal filter with which the inner wall of a through-hole does not have a burr | flash, and the processing precision of the hole diameter of a through-hole is high.

  The present invention is a method for producing a metal filter, in which a photosensitive resin composition layer is laminated on a copper substrate to form a photosensitive resin composition layer, and a predetermined portion of the photosensitive resin composition layer is activated. Exposure with light to form a cured product of the photosensitive resin composition, and a portion of the photosensitive resin composition layer other than the cured product of the photosensitive resin composition is removed by development to be exposed on a copper substrate. Development process for forming a resist pattern made of a cured product of the conductive resin composition, a first plating process for forming a first plating layer by metal plating of the copper substrate on which the resist pattern is formed, and the resist pattern and the first plating A second plating step of forming a second plating layer by metal plating with a metal different from the first plating layer on the copper substrate on which the layer is formed, and removing the copper substrate and the first plating layer by chemical dissolution , Resist pattern And a dissolution step for obtaining a structure comprising the second plating layer, and a peeling step for removing the resist pattern from the structure to obtain the second plating layer, wherein the second plating layer is a metal filter. A manufacturing method is provided.

  According to the manufacturing method of the present invention, since burrs are not generated on the inner wall of the through hole of the metal filter, it is not necessary to react and remove the burrs by reacting a chemical with the metal filter. For this reason, the hole diameter of a through-hole does not produce dispersion | variation, and the metal filter with a high processing precision of the hole diameter of a through-hole can be manufactured.

  The copper substrate may be a peelable copper foil. The peelable copper foil is a copper foil composed of at least two layers of a carrier layer and an ultrathin copper foil layer, and the copper foil layer and the carrier layer are joined to such an extent that they can be easily peeled by hand at the time of peeling. . By using peelable copper foil, the amount of copper can be reduced, the amount and time of the chemical dissolving agent required for removing the copper substrate can be reduced, and productivity can be improved.

  The metal filter has a plurality of through holes, and the opening shape of the through holes is at least one shape selected from the group consisting of a circle, an ellipse, a rounded rectangle, a rectangle, a square, and a waveform. preferable. Here, the rounded rectangle is a shape composed of two long sides of equal length and two semicircles, and is a shape shown in FIG. By having such an opening shape, cancer cells are less likely to clog the through-holes, and the concentration efficiency of cancer cells can be further improved. Moreover, it is preferable that the opening shape is a waveform in that the opening ratio of the metal filter is improved and cells can be efficiently captured. An example in the case where the opening shape is a waveform is shown in FIG.

  The metal filter may be a cancer cell concentration metal filter. The metal filter has a structure particularly suitable for concentration of cancer cells.

  The metal filter for concentrating cancer cells may be a metal filter for concentrating cancer cells circulating in blood. The metal filter has a structure particularly suitable for separating cancer cells and blood cell components circulating in blood and concentrating the cancer cells.

(A) And (B) is the schematic which shows the mechanism in which a burr | flash generate | occur | produces with the manufacturing method of the conventional metal filter. (A) is a photograph of a metal filter in which burrs are generated on the inner wall of the through hole, and (B) is a photograph of a metal filter manufactured by the manufacturing method of the present invention. (A)-(I) is process drawing explaining one Embodiment of the manufacturing method of a metal filter. (A)-(H) is process drawing explaining one Embodiment of the manufacturing method of a metal filter. (A) is a schematic perspective view of the metal filter which concerns on one Embodiment. (B) is a top view of the through-hole of the metal filter which concerns on one Embodiment. It is a schematic perspective view of the metal filter which concerns on one Embodiment.

  Hereinafter, preferred embodiments will be described with reference to the drawings in some cases, but the present invention is not limited thereto. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the drawings are exaggerated for easy understanding, and the dimensional ratios do not necessarily match those described.

  The manufacturing method of the metal filter according to the embodiment includes a lamination step of laminating a photosensitive resin composition on a copper substrate to form a photosensitive resin composition layer, and a predetermined portion of the photosensitive resin composition layer with active light. The exposure process which exposes and forms the hardened | cured material of the photosensitive resin composition, and removes parts other than the hardened | cured material of the photosensitive resin composition among photosensitive resin composition layers by image development, and photosensitive resin on a copper substrate A development process for forming a resist pattern made of a cured product of the composition, a first plating process for forming a first plating layer by metal plating a copper substrate on which the resist pattern is formed, and a resist pattern and a first plating layer A second plating step in which the formed copper substrate is metal-plated with a metal different from the first plating layer to form a second plating layer; and the copper substrate and the first plating layer are removed by chemical dissolution to form a resist Pattern A melting step of obtaining a structure comprised of a second plating layer, by removing the resist pattern from the structure comprises a separation step of obtaining the second plating layer, the second plating layer is a metal filter.

  3A to 3I are process diagrams for explaining an embodiment of a method for producing a metal filter. In this embodiment, a peelable copper foil is used as the copper substrate.

  FIG. 3A shows a peelable copper foil composed of a carrier layer 1 and a copper foil layer 2. In the laminating step shown in FIG. 3 (B), the photosensitive resin composition is laminated on the copper foil layer 2 to form the photosensitive resin composition layer 3. Subsequently, in the exposure process shown in FIG. 3C, the photosensitive resin composition layer 3 is irradiated with actinic rays (UV light or the like) through the photomask 4, and the exposed portion is photocured to form a photosensitive resin composition. A cured product 3a is formed. Subsequently, in the development step shown in FIG. 3D, a portion other than the cured product 3a of the photosensitive resin composition is removed from the photosensitive resin composition layer 3 to form the cured product 3a of the photosensitive resin composition. A resist pattern is formed. Subsequently, in the first plating step shown in FIG. 3E, the first plating layer 5 is formed on the copper foil layer 2 on which the resist pattern made of the cured product 3a of the photosensitive resin composition is formed. Subsequently, in the second plating step shown in FIG. 3F, the second plating layer 6 is formed on the copper foil layer 2 on which the resist pattern made of the cured product 3a of the photosensitive resin composition and the first plating layer 5 are formed. Form. Subsequently, as shown in FIG. 3G, the copper foil layer 2 and the carrier layer 1 of the peelable copper foil are peeled off. Subsequently, in the melting step shown in FIG. 3H, the copper foil layer 2 and the first plating layer 5 are removed by chemical dissolution. As a result, the cured product 3a of the photosensitive resin composition and the second plating layer 6 remain. Subsequently, in the peeling step shown in FIG. 3I, the resist pattern made of the cured product 3a of the photosensitive resin composition is removed, and the metal filter made of the second plating layer 6 is collected. A through hole 7 is formed in the metal filter.

  4A to 4H are process diagrams for explaining an embodiment of the production method of the present invention. In the present embodiment, a copper substrate 2 'is used instead of the peelable copper foil of the above embodiment. The manufacturing method of this embodiment is the same as that of the said embodiment except the point which does not have the process of peeling the copper foil layer 2 and the carrier layer 1 of peelable copper foil shown in FIG.3 (G). However, since the copper substrate 2 ′ is thicker than the copper foil layer 2 of the above embodiment, in the step of removing the copper substrate 2 ′ by chemical dissolution in the melting step, more chemical dissolving agent and time than the above embodiment are required. Is required.

  Then, each process of the manufacturing method of the metal filter which concerns on embodiment is demonstrated in detail.

(Lamination process)
First, the lamination process will be described. A copper substrate is used as the substrate. This makes it possible to remove the substrate by chemical dissolution. For this reason, when removing a board | substrate in the melt | dissolution process mentioned later, a metal filter is not damaged, but a deformation | transformation of the through-hole of a filter can be suppressed. For this reason, high processing accuracy of the through hole can be realized. Moreover, since copper is excellent in adhesion with the photosensitive resin composition, a resist pattern can be formed even with a small adhesion area. For this reason, a fine through-hole can be formed.

  The copper substrate is not particularly limited as long as it has copper or copper on the surface, and examples thereof include a copper foil having a thickness of 1 to 100 μm, a copper foil tape, and a peelable copper foil. From the viewpoint of workability, peelable copper foil is preferable. By using the peelable copper foil, the time for removing the copper substrate by chemical dissolution can be shortened in the melting step described later.

  As the photosensitive resin composition, either a negative type or a positive type can be used, but a negative type photosensitive resin composition is preferable. The negative photosensitive resin composition preferably contains at least a binder resin, a photopolymerizable compound having an unsaturated bond, and a photopolymerization initiator. In addition, when using a positive photosensitive resin composition, since the solubility with respect to the developing solution of the part exposed by irradiation of actinic light among photosensitive resin composition layers increases, in a development process, The exposed part will be removed. Hereinafter, the case where a negative photosensitive resin composition is used will be described.

  The thickness of the manufactured metal filter is equal to or less than the thickness obtained by subtracting the thickness of the first plating layer from the thickness of the photosensitive resin composition layer. For this reason, it is necessary to form the photosensitive resin composition layer having a thickness suitable for the thickness of the target metal filter. For example, when a metal filter having a thickness of 15 μm or less is manufactured, the photosensitivity having a thickness such that the thickness obtained by subtracting the thickness of the first plating layer from the thickness of the photosensitive resin composition is 15 μm or less. It is necessary to use a resin composition. Moreover, it is preferable to use the photosensitive resin composition with a thin film thickness, so that the hole diameter of a through-hole becomes small.

  Lamination of the photosensitive resin composition on the copper substrate is performed, for example, after removing the protective film of the sheet-like photosensitive element comprising the support film, the photosensitive resin composition and the protective film, and then the photosensitive resin of the photosensitive element. This is performed by pressure-bonding the composition layer to a copper substrate while heating. Thereby, the laminated body which consists of a copper substrate, the photosensitive resin composition layer, and the support film, and these were laminated | stacked in order is obtained.

  This lamination operation is preferably performed under reduced pressure from the viewpoint of adhesion and followability. There are no particular restrictions on the heating temperature, pressure, and other conditions for the photosensitive resin composition layer and / or copper substrate during pressure bonding, but it is preferably performed at a temperature of 70 to 130 ° C., and pressure bonding is performed at a pressure of about 100 to 1000 kPa. It is preferable to do. In addition, in press-bonding the photosensitive resin composition layer, the copper substrate may be preheated in order to improve the lamination property.

(Exposure process)
Next, the exposure process will be described. A predetermined portion of the photosensitive resin composition layer on the copper substrate is irradiated with actinic rays, and the exposed portion is photocured to form a cured product of the photosensitive resin composition. Under the present circumstances, when the support film which exists on the photosensitive resin composition layer has permeability | transmittance with respect to actinic light, it can irradiate actinic light through a support film. On the other hand, when the support film has a light-shielding property against actinic rays, the photosensitive resin composition layer is irradiated with actinic rays after the support film has been removed.

  Examples of the exposure method include a method (mask exposure method) of irradiating an image with active light through a negative or positive mask pattern called an artwork. Alternatively, a method of irradiating actinic rays in an image form by a direct drawing exposure method such as an LDI (Laser Direct Imaging) exposure method or a DLP (Digital Light Processing) exposure method may be employed.

  A general light source can be used as the active light source, for example, a carbon arc lamp, a mercury vapor arc lamp, a high-pressure mercury lamp, a xenon lamp, a gas laser such as an argon laser, a solid laser such as a YAG laser, a semiconductor laser, etc. And those that effectively emit ultraviolet light, visible light, and the like.

  The wavelength of the actinic ray (exposure wavelength) is preferably in the range of 350 to 410 nm, and more preferably in the range of 390 to 410 nm.

(Development process)
Next, the development process will be described. By removing portions of the photosensitive resin composition layer other than the cured product of the photosensitive resin composition from the copper substrate, a resist pattern made of the cured product of the photosensitive resin composition is formed on the copper substrate. . When the support film is present on the photosensitive resin composition layer, the support film is removed, and then the portion other than the cured product of the photosensitive resin composition is removed (developed). Development methods include wet development and dry development, but wet development is widely used.

  In the case of wet development, development is performed by a general development method using a developer corresponding to the photosensitive resin composition. Examples of development methods include dip method, battle method, spray method, brushing, slapping, scrapping, rocking immersion, etc., and high-pressure spray method is most suitable from the viewpoint of improving resolution. Yes. You may develop by combining 2 or more types of methods.

  Examples of the developer include an alkaline aqueous solution, an aqueous developer, an organic solvent developer, and the like. The alkaline aqueous solution is safe and stable when used as a developer, and has good operability. Examples of the base of the alkaline aqueous solution include alkali metal hydroxides such as lithium, sodium or potassium hydroxide; carbonates or bicarbonates of lithium, sodium, potassium or ammonium; alkali metals such as potassium phosphate and sodium phosphate Phosphate: Alkali metal pyrophosphates such as sodium pyrophosphate and potassium pyrophosphate are used.

  As alkaline aqueous solution, 0.1-5 mass% dilute solution of sodium carbonate, 0.1-5 mass% dilute solution of potassium carbonate, 0.1-5 mass% dilute solution of sodium hydroxide, 0.1-5 A dilute solution of mass% sodium tetraborate is preferred. The pH of the alkaline aqueous solution is preferably in the range of 9 to 11, and the temperature is adjusted according to the alkali developability of the photosensitive resin composition layer. In the alkaline aqueous solution, a surfactant, an antifoaming agent, a small amount of an organic solvent for promoting development, and the like may be mixed.

After removing portions other than the cured product of the photosensitive resin composition by development and forming a resist pattern made of the cured product of the photosensitive resin composition on the copper substrate, heating at about 60 to 250 ° C. or as necessary The resist pattern may be further cured by performing exposure at about 0.2 to 10 J / cm ² .

  Depending on the conditions of the lamination process, the exposure process, and the development process, the cross section of the through hole of the manufactured metal filter is tapered. For this reason, it may be necessary to optimize the conditions of the lamination process, the exposure process, and the development process. Conversely, it is also possible to manufacture a metal filter having a through hole with a tapered cross section by the above manufacturing method.

(First plating process)
Before forming the second plating layer to be a metal filter, the first plating layer is formed. The first plating layer is made of a material different from that of the second plating layer, and can be removed by dissolving the first plating layer selectively (without dissolving the second plating layer) in a melting step described later. When the first plating layer is formed, burrs are generated due to the plating soaking described above, but the burrs generated together with the first plating layer can be removed in the melting step described later.

  The material of the first plating layer is not particularly limited as long as it is a material that can be selectively dissolved without dissolving the second plating layer. For example, copper, nickel, gold, silver, titanium, zinc, alloys of these metals (copper alloy, nickel alloy, gold alloy, silver alloy, titanium alloy, zinc alloy) and the like can be exemplified. However, it is convenient if the material can be removed at the same time as the copper substrate, which is removed in the melting step described later. For this reason, it is preferable that the material of the first plating layer is copper.

  The first plating step is preferably performed by electroforming plating because the plating deposition rate is high and the first plating layer can be formed in a short time.

  Further, the thickness of the second plating layer (metal filter) is reduced by the thickness of the formed first plating layer. For this reason, it is preferable to set the thickness of the first plating layer to a thickness at which plating penetration occurs and does not become too thick. Therefore, the thickness of the first plating layer is preferably 0.3 to 3.0 μm, and more preferably 0.3 to 1.0 μm, for example.

(Second plating process)
Subsequently, the second plating step will be described. After the development step, plating is performed on the copper substrate to form a second plating layer. Examples of the plating method include solder plating, nickel plating, and gold plating. This second plating layer finally becomes a metal filter.

  Examples of the material of the metal filter include noble metals such as gold and silver, base metals such as aluminum, tungsten, nickel and chromium, and alloys of these metals, but are not limited thereto. The metal may be used alone, or may be used as an alloy with another metal or an oxide of a metal in order to impart functionality. Among these, it is preferable to use nickel and a metal containing nickel as a main component because corrosion is prevented and the processability and cost are excellent. Here, the main component means a component occupying 50% by mass or more of the material.

(Dissolution process)
Subsequently, the dissolution process will be described. After forming the second plating layer, the copper substrate and the first plating layer are chemically dissolved and removed. Thereby, the structure which consists of the hardened | cured material of the 2nd plating layer used as a metal filter and the photosensitive resin composition can be collect | recovered irrespective of a manual work (hand peeling). For this reason, a metal filter can be manufactured without causing damage such as wrinkles, creases, scratches, and curls, and deformation of fine through holes. As a chemical solubilizer that dissolves the copper substrate, MEC BRIGHT SF-5420B (trade name, manufactured by MEC Co., Ltd.), copper selective etching solution-CSS (Nippon Chemical Industry Co., Ltd.), or the like can be used.

  As the chemical dissolving agent for dissolving the first plating layer, when the material of the first plating layer is copper, the same chemical dissolving agent as described above for dissolving the copper substrate can be used. . In addition, when the material of the first plating layer is zinc, nitric acid, hydrochloric acid, or the like can be used as a chemical solubilizer. In addition, when the material of the first plating layer is nickel, nickel selective etching solution NC (Nippon Chemical Industry Co., Ltd.), Mekkuri Mover NH-1860 (Meck Co., Ltd.), etc. should be used as the chemical solubilizer. Can do. Further, when the material of the first plating layer is gold, a gold etching solution AURUM (Kanto Chemical Co., Inc.) or the like can be used as a chemical solubilizer. In addition, when the material of the first plating layer is silver, Sback AG-601 (Sasaki Chemical Co., Ltd.) or the like can be used as a chemical solubilizer. Further, when the material of the first plating layer is titanium, Melstrip TI-3991 (Meltex Co., Ltd.) or the like can be used as a chemical dissolving agent. In addition, a chemical dissolving agent that selectively etches away only the first plating layer can be used without dissolving the second plating layer.

  When the material of the first plating layer is copper, the copper substrate and the first plating layer can be dissolved simultaneously, so that productivity is high.

(Peeling process)
Then, a peeling process is demonstrated. After the dissolution step, the resist pattern (cured product of the photosensitive resin composition) is peeled off with, for example, a stronger alkaline aqueous solution than the alkaline aqueous solution used for development. As this strongly alkaline aqueous solution, for example, it is preferable to use a 1 to 10% by mass sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution, and it is more preferable to use a 1 to 5% by mass sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution. . By removing the resist pattern, only the second plating layer can be recovered. This second plating layer is a metal filter. FIG. 2B shows a photograph of the metal filter manufactured by this manufacturing method observed with an SEM. The magnification of the SEM image was 1000 times, and was observed at an angle of 45 ° from above the through hole. As is apparent from FIG. 2B, no burrs are present on the inner wall of the through hole of this metal filter.

  Examples of the resist pattern peeling method include an immersion method, a spray method, a method using ultrasonic waves, and the like. These may be used alone or in combination.

(Metal filter)
Since the material of the filter is metal, there are the following advantages. First, since metal is excellent in workability, the processing accuracy of the filter can be increased. Thereby, the capture rate of the components to be captured can be further improved. In addition, since metal is rigid compared to other materials such as plastic, its size and shape are maintained even when external force is applied. For this reason, blood components (particularly white blood cells) that are slightly larger than the through-holes are deformed and allowed to pass, and high-precision separation / concentration becomes possible. Among leukocytes, there are cells having the same size as CTC, and there are cases where only CTC cannot be distinguished at a high concentration only by the difference in size. However, since leukocytes are more deformable than cancer cells, they can pass through smaller pores and can be separated from CTCs by an external force such as suction or pressurization.

  Examples of the opening shape of the through hole of the metal filter include a circle, an ellipse, a rounded rectangle, a rectangle, a square, and a waveform. An example in the case where the opening shape is a waveform is shown in FIG. In FIG. 6, the metal filter 1 </ b> B is provided with a wave-shaped through hole 14 in which eight rounded rectangular perforations are connected along the long side direction (the horizontal direction in the drawing). In FIG. 6, only one row of through holes 14 is arranged in the long side direction, but a plurality of rows may be arranged. From the viewpoint of efficiently capturing cancer cells, a circle, rounded rectangle, rectangle or waveform is preferable. Further, from the viewpoint of preventing clogging of the metal filter, a rounded rectangle or a rectangle is particularly preferable.

  FIG. 5A is a schematic perspective view showing one embodiment of a metal filter that can be manufactured by the above-described manufacturing method. The metal filter 100 includes a substrate (second plating layer) 120 in which a plurality of through holes 110 are formed. The opening shape of the through hole 110 is a rounded rectangle. The arrangement of the through-holes 110 may be an aligned arrangement, a staggered arrangement with the arrangement shifted for each column, or a random arrangement arbitrarily arranged.

  FIG. 5B is a top view of the through hole 110 of the metal filter of FIG. The opening shape of the through-hole 110 is a rounded rectangle, and is a shape in which two semicircles having a radius of c are adjacent to a short side of a rectangle having a short side of a and a long side of b. In one embodiment, a, b and c are 8, 22 and 4 μm, respectively.

  The hole diameter of the through hole is set according to the size of the cancer cell to be captured. In the present specification, the hole diameter when the opening shape is other than a circle such as an ellipse, a rectangle, and a waveform means the maximum value of the diameter of a non-deformable sphere that can pass through each through hole. For example, when the opening shape is a rectangle or a rounded rectangle, the diameter of the through hole is the length of the short side of the rectangle or the rounded rectangle. Here, the length of the short side of the rounded rectangle is the length indicated by a in FIG. When the opening shape is corrugated, the diameter of the through hole is the length in the width direction of the corrugated opening (the length of the short side of the rounded rectangle forming the corrugation). When the opening shape is a rectangle or a rounded rectangle, a gap is formed in the opening in the long side direction of the opening shape even when the component to be captured is captured in the through hole. Since the liquid can pass through this gap, clogging of the filter can be prevented.

  The diameter of the inlet side of the through hole of the metal filter is preferably 5 to 100 μm, more preferably 5 to 50 μm, and particularly preferably 5 to 30 μm. Here, the inlet side of the through hole is an inflow side when a sample such as blood passes through the metal filter.

  Further, in the cross-sectional shape of the through hole, if the hole diameter of the narrowest part on the outlet side is larger than the hole diameter of the narrowest part on the inlet side, the hole diameter of the central part of the through hole exceeds the hole diameter of the narrowest part on the outlet side ( The shape which the center part swelled may be sufficient.

  The average aperture ratio of the through holes of the metal filter is preferably 5 to 50%, more preferably 10 to 40%, and particularly preferably 10 to 30%. Here, the aperture ratio refers to the ratio of the area occupied by the through holes to the entire area of the metal filter. The average aperture ratio is preferably as large as possible from the viewpoint of preventing clogging. However, if it exceeds 50%, the strength of the metal filter may be reduced, or processing may be difficult. Moreover, since it will become easy to generate | occur | produce clogging if it is less than 5%, the cancer cell concentration performance of a metal filter may fall.

  The thickness of the metal filter is preferably 3 to 50 μm, more preferably 5 to 40 μm, and particularly preferably 5 to 30 μm. When the film thickness of the metal filter is less than 3 μm, the strength of the metal filter is lowered, and the handleability may be difficult. On the other hand, when the thickness exceeds 50 μm, there is a concern that productivity will be lowered due to longer processing time, cost disadvantages due to unnecessary material consumption, and fine processing itself will be difficult.

  The above metal filter is suitable for the concentration of cancer cells. The metal filter described above can be applied to all cell-containing body fluids having cancer cells, particularly cancer cells that have been seeded and micrometastasized. Specific examples include lymph, urine, sputum, ascites, exudate, amniotic fluid, aspiration, organ washing, intestinal washing, lung washing, bronchial washing, bladder washing, stool, bone marrow and blood. The above metal filter can also be used to concentrate cancer cells by directly filtering these cell-containing body fluids. However, after removing components that do not contain cells from the cell-containing body fluids by density gradient centrifugation, etc., the metal filters are filtered. May be. Further, before the cancer cells are concentrated by the metal filter, the cancer cells in the cell-containing body fluid may be modified such as labeling.

  Cancer cells or fractions containing cancer cells isolated from cell-containing body fluids can also be cultured and grown in an appropriate medium.

  After passing the cell-containing body fluid through the metal filter, an additional liquid such as a buffer solution, a staining solution, or a culture solution may be passed through the metal filter.

Example 1
A photosensitive resin composition (PHOTEC RD-1225: thickness 25 μm, manufactured by Hitachi Chemical Co., Ltd.) is a 250 mm square substrate (MCL-E679F: peelable copper foil having a copper foil layer on a carrier layer, Hitachi Chemical Co., Ltd.) The product was laminated on a copper foil layer. Lamination was performed under the conditions of a roll temperature of 90 ° C., a pressure of 0.3 MPa, and a conveyor speed of 2.0 m / min.

Next, the glass mask was left still on the photosensitive resin composition layer of the said board | substrate. The glass mask has a light transmission part in which rectangles facing in the same direction are arranged at a constant pitch in the major axis and minor axis directions, the size of the rectangle is 8 × 30 μm, and the pitch is Both the major axis and minor axis directions were 60 μm. Subsequently, under a vacuum of 600 mmHg or less, ultraviolet rays having an exposure amount of 40 mJ / cm ² were irradiated from above the substrate on which the glass mask was placed by an ultraviolet irradiation device that irradiates parallel light.

  Next, using a 1.0% aqueous sodium carbonate solution, development is performed at a temperature of 30 ° C., a spray pressure of 0.1 MPa, and a development time of about 30 seconds to remove the photosensitive resin composition layer other than the exposed area, A resist pattern in which a cured product of a rectangular photosensitive resin composition stands vertically was formed.

  Subsequently, the exposed copper portion of the substrate on which the resist pattern is formed is plated in a copper plating solution at room temperature for about 5 minutes (first plating step), and a copper plating layer (first plating layer) having a thickness of about 1 μm is formed. Formed. The composition of the copper plating solution is shown in Table 1. As a brightener, 4.5 mL / L of Capper Grime HS-201 (Rohm and Haas Electronic Materials Co., Ltd.) was used.

  Subsequently, plating was performed in a nickel plating solution prepared to have a pH of 4.5 at a temperature of 55 ° C. for about 20 minutes (second plating step) to form a nickel plating layer (second plating layer). Table 2 shows the composition of the nickel plating solution.

  Next, the obtained copper plating layer (first plating layer) and nickel plating layer (second plating layer) were peeled off together with the peelable copper foil of the substrate. Subsequently, the copper substrate (peelable copper foil) and the copper plating layer (first plating layer) are stirred in a chemical solvent (MEC BRIGHT SF-5420B, manufactured by MEC Co., Ltd.) at a temperature of 40 ° C. for about 120 minutes. The structure which consists of hardened | cured material of the 2nd plating layer and the photosensitive resin composition was collect | recovered.

  Finally, the cured product (resist pattern) of the photosensitive resin composition in the above structure is removed by ultrasonic treatment in a resist stripping solution (P3 Poleve, manufactured by Henkel) at a temperature of 55 ° C. for about 60 minutes. A metal filter was produced. As a result, a metal filter without burrs on the inner wall of the hole and sufficiently high processing accuracy of the hole diameter was obtained.

(Example 2)
After changing the first plating step to zinc cyanide plating and forming a zinc plating layer (first plating layer) of about 1 μm and chemically dissolving the copper substrate (copper foil layer of peelable copper foil), nitric acid was added. A metal filter was produced in the same manner as in Example 1 except that the zinc plating layer (first plating layer) was used and the zinc plating layer was removed. Table 3 shows the composition of the zinc cyanide plating solution.

  As a result, a metal filter without burrs on the inner wall of the hole and sufficiently high processing accuracy of the hole diameter was obtained.

(Example 3)
Using a non-cyan electroless gold plating solution (HGS-5400, manufactured by Hitachi Chemical Co., Ltd.) for the nickel filter produced in Example 1, a gold plating coating having a thickness of about 0.15 μm under the conditions shown in Table 4 Went.

  As a result, a metal filter having excellent corrosion resistance was obtained.

(Comparative Example 1)
A filter of Comparative Example 1 was produced in the same manner as in Example 1 except that the first plating step was not performed. As a result, plating penetration occurred during the second plating step, and burrs were generated on the inner wall of the through hole of the obtained metal filter. In order to remove this burr, the metal filter was stirred in a nickel selective etching solution (NC-A, Nippon Chemical Industry) at a temperature of 45 ° C. for 5 minutes. The burr was removed by this treatment, but the hole diameter of the through hole of the metal filter was enlarged and the specification could not be satisfied. On the other hand, as described above, the metal filter produced by the method of Example 1 did not have burrs on the inner wall of the hole, and the specifications could be sufficiently satisfied with high processing accuracy.

DESCRIPTION OF SYMBOLS 1 ... Carrier layer, 2 ... Copper foil layer, 2 '... Copper plate, 3 ... Photosensitive resin composition layer, 3a ... Hardened | cured material of the photosensitive resin composition, 4 ... Photomask, 5 ... 1st plating layer, 6, DESCRIPTION OF SYMBOLS 11,120 ... 2nd plating layer (board | substrate), 7,14,110 ... Through-hole, 8 ... Board | substrate, 9 ... Metal plating layer, 10 ... Plating penetration | infiltration (burr of inner wall of hole), 100, 1B ... Metal filter, a ... short side, b ... long side, c ... radius.

Claims (5)

A method of manufacturing a metal filter,
A lamination step of laminating a photosensitive resin composition on a copper substrate to form a photosensitive resin composition layer;
Exposing a predetermined portion of the photosensitive resin composition layer with actinic rays to form a cured product of the photosensitive resin composition; and
A development step of removing a portion of the photosensitive resin composition layer other than the cured product of the photosensitive resin composition by development to form a resist pattern made of the cured product of the photosensitive resin composition on the copper substrate. When,
A first plating step of metal-plating the copper substrate on which the resist pattern is formed to form a first plating layer;
A second plating step of forming a second plating layer by metal plating the copper substrate on which the resist pattern and the first plating layer are formed with a metal different from the first plating layer;
Removing the copper substrate and the first plating layer by chemical dissolution to obtain a structure composed of the resist pattern and the second plating layer;
Removing the resist pattern from the structure to obtain the second plating layer; and
And the second plating layer is a metal filter.   The method of manufacturing a metal filter according to claim 1, wherein the copper substrate is a peelable copper foil.   The metal filter has a plurality of through holes, and the opening shape of the through holes is at least one shape selected from the group consisting of a circle, an ellipse, a rounded rectangle, a rectangle, a square, and a waveform. Item 3. A method for producing a metal filter according to Item 1 or 2.   The said metal filter is a manufacturing method of the metal filter as described in any one of Claims 1-3 which is a metal filter for cancer cell concentration.   The method for producing a metal filter according to claim 4, wherein the metal filter for concentrating cancer cells is a metal filter for concentrating cancer cells circulating in blood.