Method of manufacturing mold, mold, and microdevice

Abstract

To provide a method for manufacturing a mold capable of molding a microdevice having a minute shape difficult to machine at high precision, a mold, and a microdevice having a highly precise minute shape.SOLUTION: A microdevice of a synthetic resin having a minute shape of micron order on an outer surface is manufactured by using a mold 13 manufactured by a method for manufacturing a mold that has a master mold manufacturing process in which a master mold 10 made of a resin is manufactured according to the shape of the microdevice, and a mold manufacturing process in which the shape of the master mold 10 manufactured in the master mold manufacturing process is inversely transferred by powder injection molding to manufacture the mold 13.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a mold used in the manufacture of microdevices, a mold, and a microdevice.

Background Art

[0002] Conventionally, molds have generally been used for mass production of various industrial products. For example, in Patent Document 1, a master mold having a shape that is 2.25 to 4.0 times the volume of a desired product shape is attached in a cavity having a prismatic or cylindrical outer shape of an injection mold, injection molding of metal powder is performed, and after the molded body is degreased and sintered, the surface of the molded body is polished or ground so that the outer shape of the sintered body is prismatic or cylindrical. A method for manufacturing an insert mold for injection molding is disclosed. Further, Patent Document 2 discloses a mold and a method for manufacturing the same, which are formed of a mixture obtained by kneading a metal powder and a binder of a thermoplastic resin, and removing the binder and sintering. With the progress of technology, industrial products and their components have become more highly functional and performant, and at the same time have become smaller, and small devices (microdevices) having finer structures than before have been developed. In particular, in recent years, bionics technology, which adds new functions to products by artificially reproducing functions possessed by living organisms, has attracted attention, and its application to medical-related devices has also been studied, and further miniaturization and high definition of products are desired.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1 and Patent Document 2, first, it is necessary to produce a master mold made of a material that is easy to process, such as copper, aluminum, iron, or plastic, according to the product shape. However, it is impossible to produce a master mold for a product such as a microdevice that is small in size and has a fine shape (concavities and convexities on the micron order) on the surface by ordinary machining such as cutting and polishing. Therefore, with the manufacturing methods of Patent Document 1 and Patent Document 2, it is impossible to manufacture a mold corresponding to a microdevice. In particular, in Patent Document 2, instead of injection molding, a molded product is produced by pressing a master mold against a molding material filled and heated in a mold frame, and then degreasing and sintering to manufacture a mold. Therefore, the shape of the mold (= product) is limited to a simple one, and there is also a problem that it takes time for molding. In addition, resin molding of a microdevice having a fine shape is extremely difficult. On the other hand, by using a high-precision laser three-dimensional modeling system (a stereolithography-based 3D printer), it is possible to produce a product (microdevice) that mimics the fine structure of a living organism. However, because the system is expensive and the product becomes expensive, it is only used for some products in terms of mass productivity and cost. The present invention has been made in view of such circumstances, and an object thereof is to provide a method for manufacturing a mold that can mold a microdevice having a fine shape that is difficult to machine with high precision, the mold, and a microdevice having a high-definition fine shape.

Means for Solving the Problems

[0005] A method for manufacturing a mold according to a first invention that meets the above object is a method for manufacturing a mold used for molding a synthetic resin microdevice, a master mold manufacturing step in which a resin master mold is manufactured according to the shape of the microdevice, and a mold manufacturing step in which the shape of the master mold manufactured in the master mold manufacturing step is reversely transferred by powder injection molding to manufacture a mold.

[0006] Here, powder injection molding (PIM) includes metal injection molding (MIM) performed using a metal compound in which a resin material serving as a binder is mixed with metal powder, and ceramic injection molding (CIM) performed using a ceramics compound in which a resin material serving as a binder is mixed with ceramic powder. In addition, the mold manufacturing process includes an injection molding process in which the shape of the master mold is reversely transferred by powder injection molding to manufacture a molded body, a debinding process in which the molded body (green body) manufactured in the injection molding process is debound (the resin is removed by heating to become metal powder), and a sintering process in which the molded body debound in the debinding process is sintered (the metal powder is hardened at high temperature). After the sintering process, the mold is completed by performing finishing on the surface and outer peripheral shape.

[0007] In the method for manufacturing a mold according to the first invention, in the master mold manufacturing process, it is preferable that the master mold is manufactured by stereolithography. Here, for stereolithography, a high-precision laser three-dimensional shaping system (3D printer for resin shaping) is preferably used.

[0008] In the method for manufacturing a mold according to the first invention, on the inner surface of the mold manufactured in the mold manufacturing process, recesses having a depth of 1 μm to 5 mm and / or protrusions having a height of 1 μm to 5 mm reversely transferred from the master mold may be formed. Here, the shape, number, and arrangement of the recesses and protrusions are appropriately selected according to the use and function of the microdevice, etc. Examples of the shape of the recesses and protrusions include hemispherical, cylindrical, conical, and pyramidal shapes. Further, the recesses may be formed as concave stripes (slit-shaped, groove-shaped, or long-hole-shaped) having a semicircular, triangular, or square cross-section, and the protrusions may be formed as convex stripes having a semicircular, triangular, or square cross-section (the same applies to the second and third inventions above).

[0009] In the method for manufacturing a mold according to the first invention, the inner surface of the mold on which the recesses are formed may be a concave surface. Here, the radius of curvature of the concave surface is about 50 μm at maximum, but it is not limited thereto (the same applies to the second invention above).

[0010] The mold according to the second invention that meets the above object is a mold used for molding a synthetic resin microdevice, and has recesses with a depth of 1 μm to 5 mm and / or protrusions with a height of 1 μm to 5 mm on the inner surface.

[0011] In the mold according to the second invention, the inner surface where the recesses are formed may be a concave surface.

[0012] The microdevice according to the third invention that meets the above object is made of synthetic resin and has protrusions with a height of 1 μm to 5 mm and / or recesses with a depth of 1 μm to 5 mm on the outer surface.

[0013] In the microdevice according to the third invention, it may include a main body portion having a convex surface on at least a part of the outer surface, and one or more of the above-mentioned protrusions formed on the convex surface of the main body portion. Here, the radius of curvature of the convex surface is about 50 μm at maximum, but it is not limited thereto. Also, among the main body portion, the portion where the convex surface is formed is formed in, for example, a columnar shape, a semi-columnar shape, a conical shape, or a semi-conical shape, etc., but it is not limited thereto.

Advantages of the Invention

[0014] The method for manufacturing a mold according to the first invention enables mass production of a precise mold having a fine shape that is difficult to manufacture by machining in a short time, by reversely transferring the shape of a resin master mold by powder injection molding to manufacture the mold.

[0015] In the method for manufacturing a mold according to the first invention, in the master mold manufacturing process, when the master mold is manufactured by stereolithography, a mold with high dimensional accuracy that precisely reproduces the fine shape of a microdevice that is difficult to manufacture not only by machining but also by resin molding can be obtained.

[0016] In the method for manufacturing a mold according to the first invention, when a concave portion having a depth of 1 μm to 5 mm and / or a convex portion having a height of 1 μm to 5 mm, which are reversely transferred from a master mold, are formed on the inner surface of the mold manufactured in the mold manufacturing process, a mold for a microdevice having a fine shape, which has been conventionally difficult to manufacture, can be manufactured at low cost.

[0017] In the method for manufacturing a mold according to the first invention, when the inner surface of the mold in which the concave portion is formed is a concave surface, a mold in which fine concave portions are formed with high precision on the concave surface, which has been conventionally difficult to machine, can be obtained.

[0018] The mold according to the second invention can mass-produce microdevices having a fine shape, which have been conventionally difficult to manufacture, at low cost.

[0019] In the mold according to the second invention, when the inner surface in which the concave portion is formed is a concave surface, it is possible to cope with the molding of a microdevice having fine convex portions on the convex surface, which has been conventionally difficult to machine.

[0020] The microdevice according to the third invention has a fine shape, for which machining and resin molding have been conventionally difficult, and thus can realize functions that have never existed before.

[0021] In the microdevice according to the third invention, when it includes a main body portion having a convex surface on at least a part of the outer surface and one or more convex portions formed on the convex surface of the main body portion, the use and function are expanded by a complex fine shape, for which machining has been conventionally difficult, and the practicality is improved.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0023] Subsequently, with reference to the attached drawings, embodiments embodying the present invention will be described to facilitate understanding of the present invention. A method for manufacturing a mold according to an embodiment of the present invention is a method for mass-producing a high-definition mold used for molding a synthetic resin microdevice having a fine shape on its surface at low cost. First, as shown in FIG. 1, by a master mold manufacturing process, a resin master mold 10 is manufactured according to the shape of the microdevice. In the master mold manufacturing process, since the master mold 10 is manufactured by stereolithography, as shown in FIGS. 2(A) to (C), a master mold 10 of a microdevice having a fine shape (here, a convex portion 11) that is difficult to manufacture by machining or general resin molding can be obtained. For stereolithography, a high-precision laser three-dimensional modeling system (3D printer for resin molding) is preferably used, but it is not limited thereto.

[0024] In this embodiment, a master mold 10 of a micro-needle (an example of a micro-device) was manufactured in which a plurality of triangular pyramid-shaped convex portions 12 are arranged in a sawtooth pattern in a side view on a semi-conical convex surface 11 on the tip side of a needle. Note that, instead of manufacturing the entire shape of the micro-needle as the master mold 10 using a laser three-dimensional shaping system in this way, as shown in FIG. 3, only the shape of the semi-conical tip portion of the micro-needle where the convex portions 12 are arranged was manufactured as the master mold 10A using a laser three-dimensional shaping system, and for the other machinable parts, a metal master mold (die insert) was separately manufactured, and a master mold 10A was fixed to the tip of the metal master mold with an adhesive, and this can be used instead of the master mold 10. In this embodiment, the maximum height of the convex portion 12 was set to 16 μm, but the height of the convex portion can be appropriately selected within the range of about 1 μm to 5 mm, and the shape of the convex portion is appropriately selected according to the use of the micro-device. For example, the convex portion may be formed in a polygonal pyramid shape such as a square pyramid other than a triangular pyramid, a hemispherical shape, a conical shape, etc., or may be formed in a convex strip having a semi-circular, triangular, or square cross-section. The dimensions of the fine shapes (convex portions and concave portions) in the master mold 10 can be controlled with an accuracy on the micron order or even on the sub-micron order according to the performance (resolution and lamination pitch) of the laser three-dimensional shaping system (3D printer for resin shaping) used for optical shaping.

[0025] Next, through the mold manufacturing process shown in FIG. 4, the shape of the master mold 10 manufactured in the master mold manufacturing process is reversely transferred by powder injection molding to manufacture the mold 13. In the mold manufacturing process, first, the master mold 10 is fixed with an adhesive inside the mold frame 14 for mold forming, and the mold frame 14 is filled with a resin for powder injection molding (PIM), whereby the shape of the master mold 10 is reversely transferred by powder injection molding to manufacture a molded body (green body) 15 (injection molding process). In the present embodiment, injection molding was performed using a compound for ceramic powder injection molding (CIM) (Ceramic Compound DZF-101A manufactured by Daiichi Ceramics Co., Ltd.) obtained by kneading zirconia powder with an average particle size of 0.18 μm and a resin. Note that the type and average particle size of the ceramics contained in the injection molding resin are not limited thereto and are appropriately selected. Further, as the injection molding resin, instead of the compound for ceramic powder injection molding (CIM), a compound for metal powder injection molding (MIM) obtained by kneading a metal powder and a resin may be used. The injection molding conditions in the present embodiment are as shown in Table 1, but these conditions are appropriately selected according to the type of the injection molding resin, the shape of the master mold 10, and the like.

[0026]

Table 1

[0027] Next, the molded body (green body) 15 manufactured in the injection molding process is degreased in the degreasing process, and the molded body (metal powder body) 15a degreased in the degreasing process is sintered in the sintering process. Then, after the sintering process, if necessary, finishing of the surface and outer peripheral shape is performed to complete the mold 13. The degreasing process and the sintering process are continuously performed in the same furnace, and the temperature conditions (temperature change) during heating at that time are as shown in FIG. 5. In the present embodiment, even when molding about 40 shots is performed, breakage of the convex portion 12 of the master mold 10 does not occur, and the mold 13 having a fine shape can be favorably manufactured. Therefore, according to the method for manufacturing a mold according to the present invention, a plurality of molds 13 having a fine shape that cannot be manufactured by machining can be manufactured from a single master mold 10, and the cost of the mold 13 can be reduced.

[0028] As described above, the mold 13 of FIG. 6 manufactured in this way has, on its inner surface, a semi-conical concave surface 17 formed by inverting and transferring the convex surface 11 of the master mold 10, and a triangular pyramid-shaped concave portion 18 formed by inverting and transferring the convex portion 12 of the master mold 10. Since the green body 15 shrinks through a debinding process and a sintering process, it is necessary to form the master mold 10 slightly larger so that the mold 13 has the target (final) dimensions according to the shrinkage rate. In this embodiment, since the shrinkage rate was about 24 to 25%, in order to make the maximum radius of curvature of the semi-conical concave surface 17 on the mold 13 about 50 μm, the maximum radius of curvature of the semi-conical convex surface 11 of the master mold 10 was formed to be about 70 μm. Note that the shape and radius of curvature of the concave surface formed on the mold are not limited to this embodiment, and are appropriately selected according to the use and function of the microdevice manufactured using the mold. For example, the shape of the concave surface may be semi-cylindrical or hemispherical.

[0029] By using this mold 13, as shown in FIGS. 7(A) and (B), it becomes possible to mass-produce a synthetic resin microdevice (microneedle) 19 having a fine shape similar to that of the master mold 10 on its outer surface at low cost, expand the use of the microdevice, and popularize the microdevice. In this embodiment, the microdevice 19 includes a main body portion 21 having a semi-conical convex surface 20 on a part of its outer surface (here, the tip portion), and a plurality of convex portions 22 arranged in a serrated shape along the longitudinal direction of the main body portion 21 (convex surface 20). However, the shape of the microdevice (the shape and size of the convex surface, the main body portion, and the convex portions, and the number and arrangement of the convex surface and the convex portions) is appropriately selected according to the use and function of the microdevice. For example, no convex surface may be formed on the main body portion, convex portions may be formed on a flat surface, a concave surface may be formed on the main body portion instead of the convex surface, or a concave portion may be formed instead of the convex portion.

[0030] As described above, the embodiments of the present invention have been explained. However, the present invention is not limited to the configurations described in the above embodiments at all, and includes other embodiments and modifications conceivable within the scope of the matters described in the claims. For example, in the above embodiment, the case where the microdevice is a microneedle imitating a mosquito's needle has been described. However, the shape of the microneedle is appropriately selected. In addition, the microdevice includes various small parts having fine shapes other than the microneedle. Specifically, for example, a microchannel or a microreactor in which fine channels or channels are formed on the surface of a flat main body, a superhydrophobic chip (plate) in which a plurality of fine irregularities are formed on the surface of a flat main body, and the like can be mentioned. Note that since the mold is formed by being divided into a plurality of parts, it is possible to cope with the manufacture of a microdevice having a more complicated shape.

Explanation of Reference Numerals

[0031] 10, 10A: master mold, 11: convex surface, 12: convex portion, 13: mold, 14: mold frame, 15: formed body (green body), 15a: formed body (metal powder), 17: concave surface, 18: concave portion, 19: microdevice, 20: convex surface, 21: main body portion, 22: convex portion

Claims

1. A method for manufacturing a mold used for molding a synthetic resin microdevice, comprising: a master mold manufacturing step of manufacturing a resin master mold according to the shape of the microdevice; and a mold manufacturing step of manufacturing a mold by inversely transferring the shape of the master mold manufactured in the master mold manufacturing step by powder injection molding. The method for manufacturing a mold is characterized by having these steps.

2. The method for manufacturing a mold according to Claim 1, wherein in the master mold manufacturing step, the master mold is manufactured by stereolithography.

3. The method for manufacturing a mold according to Claim 1, wherein on the inner surface of the mold manufactured in the mold manufacturing step, recesses having a depth of 1 μm to 5 mm and / or protrusions having a height of 1 μm to 5 mm, which are inversely transferred from the master mold, are formed.

4. The method for manufacturing a mold according to Claim 3, wherein the inner surface of the mold on which the recesses are formed is a concave surface.

5. A mold used for molding a synthetic resin microdevice, characterized in that the inner surface has recesses having a depth of 1 μm to 5 mm and / or protrusions having a height of 1 μm to 5 mm.

6. The mold according to Claim 5, wherein the inner surface on which the recesses are formed is a concave surface.

7. A microdevice made of synthetic resin, characterized in that the outer surface has protrusions having a height of 1 μm to 5 mm and / or recesses having a depth of 1 μm to 5 mm.

8. The microdevice according to Claim 7, comprising a main body portion having a convex surface on at least a part of the outer surface, and one or more of the protrusions formed on the convex surface of the main body portion.

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