Mold for plastic working

Abstract

To provide a mold for plastic working comprising convex portions and concave portions that can form complex and fine concave structures with high precision.SOLUTION: The mold for plastic working forms a group of concave structures 4 having convex portions and concave portions on a workpiece 3. The mold for plastic working comprises a group of formed convex portions 2 on the upper surface of a substrate 1 to create the concave structures 4.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a mold for plastic processing for forming a group of concave structures on a forming object, and more particularly to a mold for plastic processing for forming a complex concave structure having convex or concave portions inside.

Background Art

[0002] For example, as a method for manufacturing a surface mount type ceramic package, Patent Document 1 discloses that a ceramic sheet is laminated on a substrate and then fired to obtain a ceramic substrate having a cavity (concave structure) on one side. Further, Patent Document 1 discloses that a total of four ceramic sheets are laminated to form a cavity that is recessed stepwise toward the center of the lowermost ceramic sheet.

[0003] The applicant of the present application has previously proposed electroformed metal of Patent Document 2 with respect to this type of molding die. In that case, nickel is first electroplated on the surface of a copper alloy substrate to form an electrodeposited layer, and an electrodeposition pattern having openings for electroforming is formed on the surface of the electrodeposited layer by photolithography. A disposable electroplating member having through holes corresponding to the openings is separately formed, and nickel is secondarily electroplated on the surfaces of the openings and the disposable electroplating member with the disposable electroplating member being in close contact with the surface of the electrodeposition pattern. Next, the disposable electroplating member is peeled off and removed, and further the pattern resist is removed to form convex portions for perforation on the surface of the electrodeposited layer, and a plating film is formed on the surfaces of the convex portions and the electrodeposited layer to complete the electroformed metal. The thickness of the convex portions is 200 to 300 μm. By using this electroformed metal, a group of holes for mounting micro components on a green sheet can be formed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In recent years, the miniaturization and low-profile (thinning) of surface-mounted ceramic packages have been promoted, and their outer dimensions are becoming smaller and smaller. For example, the vertical and horizontal dimensions of a miniaturized ceramic package are only 1.6 × 1.2 mm, and therefore, the mold for forming the loading recess is required to have higher dimensional accuracy and positional accuracy. However, in the method for manufacturing a multilayer substrate disclosed in Patent Document 1, since punching is performed on the ceramic sheet before firing to form openings and via holes, it becomes difficult to process the openings and via holes corresponding to the ceramic packages of the above-described minute sizes with high precision. As the ceramic package becomes smaller, the allowable error dimension with respect to the processing dimension becomes extremely small, but in the mold for punching, the variation dimension during processing becomes larger than the above-described allowable error dimension, so it becomes extremely difficult to perform plastic processing with the required precision.

[0006] In that regard, in the electroformed metal disclosed in Patent Document 2, since the formed convex portions can be formed with high precision by electroforming, a group of holes for mounting minute components on the green sheet can be precisely formed. However, since the electroformed metal disclosed in Patent Document 2 has a constant thickness of the formed convex portions, the holes formed in the green sheet can only be holes having a constant depth that matches the outer shape of the convex portions. Therefore, it is impossible to form a concave structure corresponding to the structure and function of minute parts. Specifically, it is impossible to form a complicated concave structure having convex portions and concave portions inside.

[0007] An object of the present invention is to provide a mold for plastic processing that can form a complicated and minute concave structure having convex portions and concave portions inside with high precision.

Means for Solving the Problems

[0008] The mold for plastic processing according to the present invention is a mold for forming a group of concave structures 4 having convex portions and concave portions on the processing target 3. The mold for plastic processing has a group of molding convex portions 2 provided on the upper surface of a metal substrate 1 for forming the concave structure 4, and the surface of the group of molding convex portions 2 is covered with a metal cover layer 29. As shown in FIG. 1 and FIG. 14(e), the molding convex portion 2 is composed of a plurality of metal layers laminated in multiple stages.

[0009] The plurality of metal layers are composed of electroformed layers 21, 22, and 23.

[0010] The plurality of metal layers are composed of plating layers 51 and 52.

[0011] As shown in FIG. 3, a molding area 11 having a group of molding convex portions 2 is formed on the upper surface of the substrate 1. A dummy area 13 is formed so as to surround the molding area 11. A group of dummy molding convex portions 15 having the same structure as the molding convex portions 2 are formed in the dummy area 13.

[0012] An outer peripheral area 14 surrounding the dummy area 13 is formed on the periphery of the substrate 1. The metal cover layer 29 is exposed in the outer peripheral area 14.

[0013] The upper surfaces of the respective metal layers are covered with intervening layers 26, 27, and 28.

[0014] The manufacturing method of the mold for plastic processing according to the present invention is a manufacturing method of a mold in which a group of multi-stage molding convex portions 2 are formed on the upper surface of a metal substrate 1. This manufacturing method includes a patterning step of forming a resist pattern 36, 40 having resist openings 35, 39 on an electroforming target by a photolithography method, an electroforming step of forming electroformed layers 21, 22, 23 on the surface of the electroforming target facing the resist openings 35, 39, and a pattern removing step of removing the resist pattern 36, 40. The patterning step and the electroforming step are alternately performed two or more times, and after the final electroforming step, the pattern removing step is performed to laminate and form a plurality of electroformed layers 21, 22, 23 on the upper surface of the substrate 1 to form the molding convex portion 2 in multiple stages, and a plating process is performed on the upper surface of the substrate 1 including the group of molding convex portions 2 to form a metal cover layer 29.

[0015] In another manufacturing method of the mold for plastic working according to the present invention, it is a manufacturing method of a mold in which a group of multi-stage forming convex portions 2 are formed on the upper surface of a metal substrate 1. This manufacturing method includes a patterning step of forming a resist pattern 36·40 having resist openings 35·39 on a processing target by a photolithography method, a plating step of forming plating layers 51·52 on the surface to be plated facing the resist openings 35·39, and a pattern removing step of removing the resist pattern 36·40. The patterning step and the plating step are alternately performed two or more times, and after the final plating step, the pattern removing step is performed to form a plurality of plating layers 51·52 laminated on the upper surface of the substrate 1 to form the forming convex portions 2 in multiple stages, and a plating treatment is performed on the upper surface of the substrate 1 including the group of forming convex portions 2 to form a metal cover layer 29.

[0016] The above manufacturing method includes an undercoat adjusting step of performing a plating treatment on the upper surface of the substrate 1 to form a strike plating layer 20. After performing the undercoat adjusting step, the patterning step and the electroforming step or the plating step are performed to form the first electroforming layer 21 or the first plating layer 51.

[0017] A plurality of substrates 1 are simultaneously formed on a metal master plate 44. The master plate 44 is cut with a laser cutter along the collective outer contour line L of the plurality of substrates 1 to form a substrate assembly 45. The substrate assembly 45 is cut with a wire cut electric discharge machine along the outer contour lines of the individual substrates 1 to form a plurality of molds for plastic working.

Effect of the Invention

[0018] In the die for plastic working according to the present invention, a group of forming projections 2 for forming a concave structure 4 having convex portions and concave portions is provided on the upper surface of a metal substrate 1, and the surface of the group of forming projections 2 is covered with a metal cover layer 29. Further, the forming projections 2 are composed of a plurality of metal layers laminated in multiple stages. According to such a die for plastic working, a high-precision forming projection 2 excellent in dimensional accuracy and positional accuracy can be accurately formed as compared with a die having a conventional structure. Therefore, by performing plastic working on a workpiece 3 using a die having a group of forming projections 2, a concave structure 4 having a complicated and fine structure with convex portions and concave portions inside can be accurately formed with high precision and only by one-time plastic working. Further, by covering the surface of the group of forming projections 2 with the metal cover layer 29, the metal cover layer 29 at the portion covering the outer corner portion of the forming projection 2 can be rounded. Therefore, when the workpiece 3 subjected to plastic working is released from the die, the workpiece 3 can be easily released.

[0019] When a plurality of metal layers are formed by electroforming layers 21, 22, 23, a concave structure 4 having a complicated and fine structure with convex portions and concave portions inside can be accurately formed with high precision.

[0020] When a plurality of metal layers are formed by plating layers 51, 52, similar to the case where the metal layers are formed by the electroforming layers 21, 22, 23, a concave structure 4 having a complicated and fine structure can be accurately formed with high precision, and a die for plastic working can be provided at a lower cost.

[0021] A molding area 11 having a group of molding projections 2 is formed on the upper surface of a substrate 1, and a dummy area 13 is formed so as to surround the molding area 11. When a group of dummy molding projections 15 having the same structure as the molding projections 2 are formed in the area 13, the layer thickness of the molding projections 2 formed in the molding area 11 can be made uniform. This is for the following reasons. During electroforming, the amount of electrodeposited metal per unit area deposited on the substrate 1 is substantially constant. However, if the shape, outer dimensions, or adjacent pitch of each molding projection 2 are the same, the layer thickness of all the molding projections 2 will be the same. However, for example, even if the shape and outer dimensions of each molding projection 2 are the same, if the adjacent pitch is different, differences will occur in the layer thicknesses of the electroformed layers 21, 22, and 23 according to the difference in the arrangement density of the molding projections 2. The layer thickness of the molding projections 2 becomes larger in the region where the arrangement density of the molding projections 2 is coarse, and the layer thickness of the molding projections 2 becomes smaller in the region where the arrangement density of the molding projections 2 is dense. In order to eliminate such variations in layer thickness, a dummy area 13 is formed around the molding area 11, and a group of dummy molding projections 15 having the same structure as the molding projections 2 are formed in the area 13 to equalize the layer thickness of the molding projections 2 formed in the molding area 11. Incidentally, when the dummy area 13 is not provided, the layer thickness of the molding projections 2 located closer to the periphery of the molding area 11 becomes larger than the layer thickness of the molding projections 2 formed closer to the center of the molding area 11.

[0022] An outer peripheral area 14 is provided at the periphery of the substrate 1. When the metal cover layer 29 is exposed in the area 14, the outer edge of the mold having a group of molding projections 2 can be specified by the outer peripheral area 14. In many cases, in order to manufacture the mold at low cost, a large number of substrates 1 are simultaneously formed on a large original plate 44 and finally cut into individual substrates 1. In that case, by cutting the substrate 1 using the outer peripheral area 14 as an index, the substrate 1 can be cut accurately.

[0023] If the upper surfaces of the electroforming layers 21, 22, and 23 are covered with intervening layers 26, 27, and 28 that have excellent adhesion to the electroforming layers 21, 22, and 23, the adhesion strength between adjacent electroforming layers 21, 22, and 23 can be increased, and the structural strength of the formed convex portion 2 can be enhanced. Therefore, the durability of the mold provided with a group of formed convex portions 2 can be improved. This is due to the following reasons. Each of the electroforming layers 21, 22, and 23 is formed by electrodepositing, for example, a nickel-cobalt alloy. However, if the second electroforming layer 22 is directly electrodeposited on the first electroforming layer 21, or the third electroforming layer 23 is directly electrodeposited on the second electroforming layer 22, the adjacent electroforming layers 21, 22, and 23 cannot be firmly adhered to each other. This is because when the electrodeposited metal is a nickel-based metal, the compatibility of adhesion is poor and sufficient adhesion strength cannot be obtained. However, if intervening layers 26, 27, and 28 are formed on the upper surfaces of the electroforming layers 21, 22, and 23, and the second or third electroforming layer 23 is formed on the upper surfaces thereof, the adjacent electroforming layers 21, 22, and 23 can be firmly integrated via the intervening layers 26, 27 to enhance the adhesion strength. Similarly, when a metal cover layer 29 is formed on the upper surfaces of the outermost electroforming layers 22, 23, the metal cover layer 29 and the outermost electroforming layers 22, 23 can be firmly integrated via the intervening layers 26, 27, and 28 to enhance the adhesion strength. Also, the upper surfaces of the plating layers 51, 52 may be covered with an intervening layer, and the same effect can be obtained in that case. Note that there are no particular restrictions on the material for forming the intervening layers 26, 27, and 28, but copper is preferable when each metal layer or the metal cover layer 29 is formed of a nickel-cobalt alloy.

[0024] In the method for manufacturing a mold for plastic working according to the present invention, the patterning process and the electroforming process are alternately performed two or more times, and after the final electroforming process, a pattern removing process is performed to laminate and form a plurality of electroformed layers 21, 22, and 23 on the upper surface of the substrate 1, and the forming convex portions 2 are formed in multiple stages. Further, a plating process is performed on the upper surface of the substrate 1 including a group of forming convex portions 2 to form a metal cover layer 29. According to such a method for manufacturing a mold, a group of highly accurate forming convex portions 2 excellent in dimensional accuracy and positional accuracy can be accurately formed as compared with a mold having a conventional structure. Also, since the patterning process and the electroforming process are alternately performed two or more times to laminate a plurality of electroformed layers 21, 22, and 23 and form the forming convex portions 2 in multiple stages, the degree of freedom in the structure of the forming convex portions 2 is high, and the forming convex portions 2 for forming a concave structure 4 having a more complex shape can be surely formed. Further, since the metal cover layer 29 is formed on the upper surface of the substrate 1 including a group of forming convex portions 2, the metal cover layer 29 covering the outer corner portions of the forming convex portions 2 can be rounded. Therefore, when the work piece 3 is released from the mold during plastic working, the work piece 3 can be smoothly and easily released. The fine concave structure 4 formed on the work piece 3 is not damaged during release.

[0025] In another method for manufacturing a mold for plastic working according to the present invention, the patterning process and the plating process are alternately performed two or more times, and after the final plating process, a pattern removing process is performed to laminate and form a plurality of plating layers 51, 52 on the upper surface of the substrate 1, and the forming convex portions 2 are formed in multiple stages. According to such a method for manufacturing a mold, a group of highly accurate forming convex portions 2 excellent in dimensional accuracy and positional accuracy can be accurately formed as compared with a mold having a conventional structure. Also, since the patterning process and the plating process are alternately performed two or more times to laminate a plurality of plating layers 51, 52 and form the forming convex portions 2 in multiple stages, the degree of freedom in the structure of the forming convex portions 2 is high, and the forming convex portions 2 for forming a concave structure 4 having a more complex shape can be surely formed. Further, since the metal cover layer 29 is formed on the upper surface of the substrate 1 including a group of forming convex portions 2, the metal cover layer 29 covering the outer corner portions of the forming convex portions 2 can be rounded. Therefore, when the work piece 3 is released from the mold during plastic working, the work piece 3 can be smoothly and easily released. The fine concave structure 4 formed on the work piece 3 is not damaged during release.

[0026] In the above manufacturing method, after forming the strike plating layer 20 in the substrate adjustment step, when performing the patterning step and the electroforming step or the plating step to form the first electroforming layer 21 or the first plating layer 51, the first electroforming layer 21 or the first plating layer 51 and the substrate 1 can be firmly integrated via the strike plating layer 20, enhancing the adhesion strength between the two.

[0027] The original plate 44 on which a plurality of substrates 1 are simultaneously formed is cut with a laser cutter along the collective outer contour line L of the plurality of substrates 1 to form a substrate assembly 45. Further, cutting the substrate assembly 45 with a wire cut electric discharge machine along the outer contour line of each individual substrate 1 is to avoid the formed convex portions 2 formed in the forming area 11 from being thermally deformed by the heat during cutting. Specifically, when cutting the original plate 44 with a laser cutter along the collective outer contour line L of a large number of substrates 1, the cutting of the assembly can be performed quickly. Also, since the cutting position by the laser is sufficiently separated from each substrate 1, the formed convex portions 2 formed in the forming area 11 will not be thermally deformed by the heat during cutting. However, when cutting each individual substrate 1 from the substrate assembly 45, since the cutting position approaches the forming area 11, there is a risk that the formed convex portions 2 formed in the forming area 11 will be thermally deformed by the heat during cutting. To avoid such thermal deformation of the formed convex portions 2 due to the heat during cutting, when cutting each individual substrate 1 from the substrate assembly 45, a wire cut electric discharge machine that performs cutting in a water tank is used.

Brief Description of the Drawings

[0028]

Figure 1

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Figure 14

Mode for Carrying Out the Invention

[0029] (Example 1) FIGS. 1 to 8 show Example 1 in which a mold for plastic working according to the present invention is applied to a stamp mold for plastic working a ceramic sheet. In FIG. 2, the stamp mold is configured by forming a group of forming convex portions 2 on the upper surface of a substrate 1 made of a stainless steel plate having a thickness of 1.0 to 10.0 mm. Using this mold, a group of loading recesses (concave structures) 4 for accommodating minute parts such as electronic components and sensors for surface mounting are formed in a ceramic sheet (object to be processed) 3 before firing. In FIG. 2, reference numeral 5 is a fixing base for supporting the ceramic sheet 3, and reference numeral 6 is a movable base that moves up and down to press the mold for plastic working against the ceramic sheet 3.

[0030] As shown in FIG. 3, the stamp die includes a molding area 11 including the central portion of a rectangular substrate 1, a dummy area 13 surrounding the periphery of the molding area 11, and an outer peripheral area 14 formed on the periphery of the substrate 1 and surrounding the dummy area 13. In the molding area 11, a group of molding protrusions 2 are formed in a matrix shape, and in the dummy area 13, a group of dummy molding protrusions 15 are formed in a matrix shape. The molding protrusions 2 and the dummy molding protrusions 15 are formed in a circular shape, but may be formed in a polygonal shape or an elliptical shape. In the outer peripheral area 14, neither the molding protrusions 2 nor the dummy molding protrusions 15 are formed, and a cover plating layer 29 described later is exposed in the outer peripheral area 14. The length of the long side portion of the substrate 1 is 200 mm, and the length of the short side portion is 150 mm.

[0031] The molding protrusions 2 and the dummy molding protrusions 15 are formed with the same structure, but only the loading recesses 4 molded by the molding protrusions 2 provided in the molding area 11 are used as ceramic packages. As described above, forming the dummy area 13 around the molding area 11 and forming the dummy molding protrusions 15 having the same structure as the molding protrusions 2 in the area 13 is to make the density of the molding protrusions 2 formed in the molding area 11 and the dummy area 13 uniform and to equalize the layer thickness (height) of the molding protrusions 2 in the molding area 11.

[0032] More specifically, the amount of electrodeposited metal per unit area electrodeposited on the substrate 1 during electroforming is substantially constant. If the shape, outer dimensions, or adjacent pitch of each forming convex portion 2 are the same, the layer thicknesses of all the forming convex portions 2 will be the same. However, for example, even if the shapes and outer dimensions of each forming convex portion 2 are the same, if the adjacent pitch is different, a difference in layer thickness will occur according to the difference in the arrangement density of the forming convex portions 2. The larger the area where the arrangement density of the forming convex portions 2 is coarse, the larger the layer thickness of the forming convex portions 2, and the denser the area where the arrangement density of the forming convex portions 2 is, the smaller the layer thickness of the forming convex portions 2. In order to eliminate such variations in layer thickness, a dummy area 13 is formed around the forming area 11, and a group of dummy forming convex portions 15 having the same structure as the forming convex portions 2 are formed in the area 13 so that the layer thicknesses of the forming convex portions 2 formed in the forming area 11 become uniform.

[0033] Figures 1 and 4 show the detailed structure of the forming projection 2. The forming projection 2 includes a first electroforming layer (metal layer) 21 formed on the upper surface of a substrate (electroforming target) 1, a copper plating layer (intervening layer) 26 formed on the upper surface of the first electroforming layer 21 which is the electroforming target, a second electroforming layer (metal layer) 22 of the second layer formed on the upper surface of the copper plating layer 26, a copper plating layer (intervening layer) 27 formed on the upper surface of the second electroforming layer 22, and a cover plating layer (metal cover layer) 29 formed on the upper surface of the copper plating layer 27. In order to improve the adhesion between the substrate 1 and the first electroforming layer 21, it is preferable to form a strike plating layer 20 on the substrate 1, and nickel, copper, gold, and silver are suitable as the forming material of this strike plating layer 20. As shown in Figures 3 and 4, in this embodiment, the first electroforming layer 21 is formed in a circular shape, and the second electroforming layer 22 is formed on the upper surface of the periphery and the central part of the upper surface thereof, showing the case where a concentric forming projection 2 having a pair of left and right parallel recesses 30 in the formation region of the second electroforming layer 22 is formed. Both the first electroforming layer 21 and the second electroforming layer 22 are formed by electroforming nickel-cobalt, but in order to increase the adhesion strength of the second electroforming layer 22 to the first electroforming layer 21, a copper plating layer 26 is formed on the upper surface of the first electroforming layer 21. Similarly, in order to increase the adhesion strength of the cover plating layer 29 made of a nickel-cobalt plating layer to the second electroforming layer 22, a copper plating layer 27 is formed on the upper surface of the second electroforming layer 22. By covering the upper surface of the substrate 1 including a group of forming projections 2 with the cover plating layer 29, the cover plating layer 29 at the portion covering the outer corner portion of the forming projection 2 can be rounded. Therefore, when the processed object 3 subjected to plastic processing is released from the mold, the processed object 3 can be released smoothly and easily. The fine concave structure 4 formed on the ceramic sheet 3 is not damaged during release.

[0034] As described above, by forming the loading recess 4 with the forming projection 2 formed in multiple stages by the first electroforming layer 21 and the second electroforming layer 22, as shown in Figure 2, having a pair of left and right protruding ribs 31 on the bottom surface The loading recess 4 can be formed. The thickness of the first electroformed layer 21 is 100 to 200 μm, and the thickness of the second electroformed layer 22 is 10 to 100 μm. The thickness of the strike plating layer 20 is preferably 0.01 to 1 μm, the thickness of the copper plating layers 26, 27, and 28 is preferably 1 to 5 μm, and the thickness of the cover plating layer 29 is preferably 1 to 10 μm.

[0035] The stamp mold with the above structure is manufactured through a substrate adjustment process, a patterning process, an electroforming process, a pattern removal process, a grinding process performed after the electroforming process, and a plating process. In the substrate adjustment process, a strike plating layer 20 is formed by performing a plating process on the upper surface of the stainless-steel substrate 1. Although the strike plating layer 20 is formed on the entire upper surface of the substrate 1, it may also be formed on the surface of the substrate 1 exposed in the resist opening 35 after the following patterning process.

[0036] (Patterning Process) In the first patterning process, as shown in FIGS. 5(a) and 5(b), a photoresist layer 33 is formed on the upper surface of the strike plating layer (electroforming target) 20, and exposure is performed with a photomask 34 in close contact with the upper surface thereof. Development and drying are then carried out, and the unexposed portion is dissolved and removed to form a resist pattern 36 having a resist opening 35 on the upper surface of the strike plating layer 20. In this way, in the first patterning process, the first-layer resist pattern 36 is formed by photolithography.

[0037] (Electroforming Process, Grinding Process, and Plating Treatment) In the first electroforming process, as shown in FIG. 5(c), the substrate 1 on which the resist pattern 36 is formed is immersed in the electroforming solution, and electrodeposited metal is grown on the strike plating layer 20 exposed in the resist opening 35 until it slightly exceeds the thickness of the resist pattern 36 to form the first electroforming layer 21. As shown in FIG. 5(d), grinding is performed on the upper surface side of the obtained first electroforming layer 21 of the substrate 1 to adjust the thickness of the first electroforming layer 21 to a predetermined thickness. Further, copper plating treatment is performed on the upper surface side of the first electroforming layer 21 to form a copper plating layer (intervening layer) 26. As described above, when the first electroforming layer 21 is formed after forming the strike plating layer 20 in the substrate conditioning process, compared with the case where the first electroforming layer 21 is directly formed on the upper surface of the substrate 1, the first electroforming layer 21 and the substrate 1 are firmly integrated via the strike plating layer 20, and the adhesion strength between the substrate 1 and the molding convex portion 2 can be enhanced.

[0038] (Patterning Process) In the second patterning process, as shown in FIGS. 6(a) and 6(b), a photoresist layer 37 is formed on the upper surface of the copper plating layer (electroforming target) 26, and exposed in a state where a photomask 38 is adhered to the upper surface thereof, developed and dried, and the unexposed portion is dissolved and removed to form a resist pattern 40 having a resist opening 39 on the upper surface side of the first electroforming layer 21. In this way, the second resist pattern 40 is formed by photolithography.

[0039] (Electroforming Process and Grinding Process) In the second electroforming process, as shown in FIG. 6(c), the substrate 1 on which the resist pattern 40 is formed is immersed in the electroforming solution, and electrodeposited metal is grown on the copper plating layer 26 exposed in the resist opening 39 until it slightly exceeds the thickness of the resist pattern 40 to form the second electroforming layer 22. As shown in FIG. 6(d), grinding is performed on the upper surface side of the second electroforming layer 22 to adjust the thickness of the second electroforming layer 22 to a predetermined thickness.

[0040] (Pattern Removal Process and Plating Treatment) In the pattern removal step, the resist patterns 36 and 40 are dissolved and removed to expose the first electroformed layer 21 and the second electroformed layer 22. Next, as shown in FIG. 7(a), copper plating is performed on the upper surface side of the second electroformed layer 22 to form a copper plating layer (intermediate layer) 27. Further, as shown in FIG. 7(b), nickel-cobalt plating is performed on the upper surface side of the copper plating layer 27 to form a cover plating layer 29, completing the stamp mold. As described above, in this embodiment, the patterning step and the electroforming step are each performed twice to form the molding convex portions 2 in multiple stages. Note that the cover plating layer 29 may be formed only on the surfaces of a group of the molding convex portions 2. Further, the cover plating layer 29 is preferably formed by bright plating.

[0041] As described above, when the upper surfaces of the electroformed layers 21 and 22 are covered with the copper plating layers 26 and 27, the adhesion strength between the adjacent electroformed layers 21 and 22 can be increased, enhancing the structural strength of the molding convex portions 2. Therefore, the durability of the mold provided with a group of the molding convex portions 2 can be improved. Each of the electroformed layers 21 and 22 is formed by electrodepositing, for example, a nickel-cobalt alloy. However, when the second electroformed layer 22 is directly electrodeposited on the first electroformed layer 21, the adjacent electroformed layers 21 and 22 cannot be firmly adhered to each other. This is because sufficient adhesion strength cannot be obtained when the electrodeposited metals are of the same material. However, when the copper plating layer 26 is formed on the upper surface of the electroformed layer 21 and the second electroformed layer 22 is formed on the upper surface thereof, the adjacent electroformed layers 21 and 22 can be firmly integrated via the copper plating layer 26, enhancing the adhesion strength. Similarly, when the cover plating layer 29 is formed on the upper surface of the outermost electroformed layer 22, the cover plating layer 29 and the outermost electroformed layer 22 can be firmly integrated via the copper plating layer 27, enhancing the adhesion strength.

[0042] The stamp mold is formed through the above steps in principle. In practice, as shown in Fig. 8(a), a stainless steel sheet 44 with a large area is prepared, and nine substrates 1 are simultaneously formed on its plate surface so that the stamp mold can be manufactured at a lower cost. In this case, the photomasks 34 and 38 are formed in a size that covers nine substrates 1. The sheet 44 that has undergone a series of processes is cut with a laser cutter along the outer contour line L of the set of nine substrates 1 to form a substrate assembly 45 having the nine substrates 1 shown in Fig. 8(b). Further, by cutting the substrate assembly 45 with a wire cut electric discharge machine along the outer contour lines of the individual substrates 1, nine plastic working molds shown in Fig. 8(c) can be obtained.

[0043] When the sheet 44 is cut with a laser cutter along the outer contour line L of the set of nine substrates 1, the cutting of the set of substrates 1 can be performed quickly. Also, since the cutting position by the laser is sufficiently separated from each substrate 1, the formed convex portions 2 formed in the forming area 11 are not thermally deformed by the heat during cutting. However, when cutting the nine substrates 1 from the substrate assembly 45, since the cutting position approaches the forming area 11, the formed convex portions 2 formed in the forming area 11 may be thermally deformed by the heat during cutting. In order to avoid such thermal deformation of the formed convex portions 2 due to the heat during cutting, when cutting the nine substrates 1 from the substrate assembly 45, a wire cut electric discharge machine that performs cutting in a water tank is used.

[0044] Each individual stamp mold is completed by washing and drying. By performing plastic working on the ceramic sheet 3 using the obtained stamp mold, a group of loading recesses 4 having a complex and fine structure with convex and concave portions inside can be formed with high precision. After loading minute parts such as crystal resonators, crystal oscillators, acceleration sensors, angular velocity sensors, etc. into the loading recesses 4 of the fired ceramic sheet, by sealing the opening surface of the loading recess with a lid, a surface mount type ceramic package that is vacuum-sealed or hermetically sealed can be obtained.

[0045] According to the mold for plastic processing formed by electroforming as described above, compared with the mold of the conventional structure, the highly precise forming convex portion 2 excellent in dimensional accuracy and positional accuracy can be accurately formed. Therefore, by subjecting the processing target 3 to plastic processing using a mold provided with a group of forming convex portions 2, the loading recess 4 having a complicated and fine structure with convex portions and concave portions inside can be surely formed with high precision and only by one-time plastic processing.

[0046] When the outer peripheral area 14 is provided at the periphery of the substrate 1 and the cover plating layer 29 is exposed in the area 14, the appearance of the dummy area 13 and the outer peripheral area 14 can be made significantly different, and the shape of the mold for plastic processing can be clearly recognized. Further, by bringing the electrodeposition amount per unit area of the dummy area 13 and the outer peripheral area 14 close to the electrodeposition amount per unit area of the forming area 11, it is possible to contribute to the uniformization of the layer thickness of the forming convex portion 2 in the forming area 11. Note that it is not necessary to expose the cover plating layer 29 in the outer peripheral area 14. If the dummy forming convex portion 15 is formed in the area 14, it can contribute more to the uniformization of the layer thickness of the forming convex portion 2 in the forming area 11. In this embodiment, the forming convex portion 2 and the dummy forming convex portion 15 have the same structure, but this is not necessary, and the structures of the forming convex portion 2 and the dummy forming convex portion 15 may be different. The main point is that the electrodeposition amount per unit area of the forming area 11 and the dummy area 13 including the outer peripheral area 14 may be the same. Incidentally, if the structures of the forming convex portion 2 and the dummy forming convex portion 15 are different, even if the molded products formed by the respective convex portions 2 and 15 are mixed, the two molded products can be easily identified, so that unnecessary molded products can be surely removed.

[0047] (Example 2) Fig. 9 shows the formed convex portion 2 according to Example 2. In Example 2, the formed convex portion 2 was formed in multiple stages with the first electroforming layer 21 of the first layer, the second electroforming layer 22 of the second layer, and the third electroforming layer (metal layer) 23 of the third layer. Specifically, the second electroforming layer 22 was formed only around the upper surface of the first electroforming layer 21, and the third electroforming layer 23 was formed only around the upper surface of the second electroforming layer 22, forming a recess 48 that is recessed stepwise toward the center of the first electroforming layer 21. The third electroforming layer 23 was formed after the third electroforming process through the formation of the resist pattern of the third layer by photolithography. In this example, the copper plating layer 27 formed on the upper surface of the second electroforming layer 22 became the object of electroforming when the third electroforming process was performed. Reference numeral 28 is a copper plating layer (intervening layer) formed on the upper surface of the third electroforming layer 23. As described above, in this example, the patterning process and the electroforming process were each performed three times to form the formed convex portion 2 in multiple stages. Although not shown, similar to the formed convex portion 2 described above, copper plating was performed on the upper surfaces of the electroforming layers 21 to 23 to form copper plating layers, and the same copper plating layers were also formed in the following examples. Since the rest is the same as the previous example, the same members are denoted by the same reference numerals and the description thereof is omitted. The same shall apply to the following examples.

[0048] (Example 3) Fig. 10 shows the formed convex portion 2 according to Example 3. In Example 3, the formed convex portion 2 was formed in multiple stages with the first electroforming layer 21 of the first layer, the second electroforming layer 22 of the second layer, and the third electroforming layer 23 of the third layer. Specifically, the second electroforming layer 22 was formed only at the center of the upper surface of the first electroforming layer 21, and the third electroforming layer 23 was formed only at the center of the upper surface of the second electroforming layer 22, forming the formed convex portion 2 with the upper surface of the third electroforming layer 23 as the top in a stepwise manner. The third electroforming layer 23 can be formed after the third electroforming process through the formation of the resist pattern of the third layer by photolithography in the same manner as in the above example, and the third electroforming layer 23 can also be formed in the same manner in the following examples.

[0049] (Example 4) Fig. 11 shows the formed convex portion 2 according to Example 4. In Example 4, the formed convex portion 2 was formed in multiple stages with the first electroforming layer 21 of the first layer, the second electroforming layer 22 of the second layer, and the third electroforming layer 23 of the third layer. Specifically, the second electroforming layer 22 was formed near the center of the upper surface of the first electroforming layer 21, and a third electroforming layer 23 thicker than the second electroforming layer 22 was formed around the upper surface of the first electroforming layer 21 and at the center of the upper surface of the first electroforming layer 21, thereby forming the formed convex portion 2 having two types of convex portions with different heights and concave portions in multiple stages.

[0050] (Example 5) Fig. 12 shows the formed convex portion 2 according to Example 5. In Example 5, in the above Example 1, the copper plating layers 26 and 27 formed on the upper surface sides of the first electroforming layer 21 and the second electroforming layer 22 were omitted, the second electroforming layer 22 was formed on the upper surface of the first electroforming layer 21 of the first layer, and a nickel-cobalt plating treatment was performed on the upper surface sides of both electroforming layers 21 and 22 to form a cover plating layer 29. In this example, the first electroforming layer 21 serves as the electroforming target when the second electroforming layer 22 is formed.

[0051] (Example 6) Figs. 13 and 14 are process explanatory diagrams showing the manufacturing process of the stamp mold according to Example 6. Therefore, the stamp mold is manufactured through a patterning process, a plating process, a pattern removal process, a grinding process performed after the plating process, and the like. Note that as the plating treatment in the plating process, there are various treatment methods such as vapor deposition and sputtering. Hereinafter, the case of performing the plating treatment by electroless plating will be described.

[0052] (Patterning Process) In the first patterning process, as shown in Figs. 13(a) and 13(b), a photoresist layer 33 is formed on the upper surface of the substrate 1, exposed in a state where a photomask 34 is adhered to the upper surface thereof, developed and dried, and the unexposed portion is dissolved and removed to form a resist pattern 36 having a resist opening 35. Thus, in the first patterning process, the first-layer resist pattern 36 is formed by photolithography.

[0053] (Plating Process and Grinding Process) In the first plating process, as shown in FIG. 13(c), the substrate 1 on which the resist pattern 36 is formed is immersed in a plating bath for electroless plating, and a plating layer is grown on the substrate (the object to be plated) 1 exposed in the resist opening 35 to form a first plating layer (metal layer) 51. As shown in FIG. 13(d), grinding is performed on the upper surface side of the first plating layer 51 of the obtained substrate 1 to adjust the thickness of the first plating layer 51 to a predetermined thickness.

[0054] (Patterning process) In the second patterning process, as shown in FIGS. 14(a) and 14(b), a photoresist layer 37 is formed on the upper surface of the first plating layer 51, and exposure is performed in a state where a photomask 38 is adhered to the upper surface thereof, followed by development and drying. The unexposed portion is dissolved and removed to form a resist pattern 40 having a resist opening 39 on the upper surface side of the first plating layer 51. In this way, the second resist pattern 40 is formed by photolithography.

[0055] (Plating process and grinding process) In the second plating process, as shown in FIG. 14(c), the substrate 1 on which the resist pattern 40 is formed is immersed in a plating bath for electroless plating, and a plating layer is grown on the upper surface of the first plating layer (the object to be plated) 51 exposed in the resist opening 39 to form a second plating layer 52. As shown in FIG. 14(d), grinding is performed on the upper surface side of the second plating layer 52 to adjust the thickness of the second plating layer 52 to a predetermined thickness.

[0056] (Pattern removal process) In the pattern removal process, the resist patterns 36 and 40 are dissolved and removed to expose the first plating layer 51 and the second plating layer 52. Then, a metal cover layer 29 is formed on the upper surface of the substrate 1 including a group of forming projections 2 to complete the stamp mold. As described above, in this embodiment, the patterning process and the plating process are each performed twice to form the forming projections 2 in multiple stages. If necessary, a third plating layer can be formed to form the forming projections 2 in multiple stages. Note that the upper surfaces of the first plating layer 51 and the second plating layer 52 may be covered with intervening layers (26, 27, 28).

[0057] According to the mold for plastic working formed by the plating method as described above, similar to the mold of Example 1, compared with the mold of the conventional structure, the high-precision forming projections 2 excellent in dimensional accuracy and positional accuracy can be accurately formed. Therefore, by performing plastic working on the work piece 3 using a mold provided with a group of forming projections 2, the loading recess 4 having a complicated and fine structure with convex and concave portions inside can be surely formed with high precision and only by one-time plastic working. Further, compared with the case where the forming projections 2 are formed by a plurality of electroforming layers 21, 22, and 23, the mold for plastic working can be provided at a lower cost.

[0058] In Example 1, as shown in FIGS. 6(a) to 6(d), a photoresist layer 37 was formed on the upper surface of the copper plating layer 26, exposed through a photomask 38, developed and dried, and the unexposed portion was dissolved and removed to form the second resist pattern 40. Further, the substrate 1 was immersed in an electroforming solution to form the second electroforming layer 22. As described above, the second resist pattern 40 is formed by dissolving and removing the unexposed portion of the photoresist layer 37, but resist residues may be generated on the upper surface of the first electroforming layer 21 when the unexposed portion is dissolved and removed. Thus, if resist residues are present, the adhesion strength between the first electroforming layer 21 and the second electroforming layer 22 will decrease.

[0059] In order to prevent the decrease in the adhesion strength as described above, after forming the resist pattern 40, an etching process is performed to remove the copper plating layer 26 exposed in the resist opening 39, and the resist residue can be reliably removed. Therefore, after performing the etching process, by forming the second electroformed layer 22, the influence of the resist residue can be eliminated, and the adhesion strength of the second electroformed layer 22 to the first electroformed layer 21 can be improved. Further, after dissolving and removing the resist patterns 36 and 40, a cover plating layer 29 is formed. In the state where the resist patterns 36 and 40 are dissolved and removed, the copper plating layer 26 directly under the resist pattern 40 is exposed on the upper surface of the first electroformed layer 21. However, after removing the exposed copper plating layer 26, the cover plating layer 29 may be formed, or the cover plating layer 29 may be formed without removing the copper plating layer 26.

[0060] Also in the stamp mold described in Example 5, by performing the same etching process as described above, the adhesion strength between the first electroformed layer 21 and the second electroformed layer 22 can be improved. In Example 5, as shown in FIG. 12, in the form of a mold in which there is no copper plating layer (intervening layer) between the first electroformed layer 21 and the second electroformed layer 22 and between the second electroformed layer 22 and the cover plating layer 29, in the process of manufacturing a mold of such a form, a copper plating layer may be formed. Specifically, as shown in FIGS. 5(a) to 5(c) of Example 1, after performing the first patterning process and the electroforming process, as shown in FIG. 5(d), a copper plating layer 26 is formed on the upper surface of the first electroformed layer 21. This serves to prevent the decrease in the adhesion strength described above. Thus, after forming the copper plating layer 26 on the upper surface of the first electroformed layer 21, the second patterning process is performed as shown in FIGS. 6(a) and 6(b). During the resist development in the second patterning process, resist residues may be generated and may be present in the resist opening 39. In that case, by removing the copper plating layer 26 exposed in the resist opening 39, the resist residues can be removed together. After that, by performing the second electroforming process, the adhesion strength between the first electroformed layer 21 and the second electroformed layer 22 can be improved. After that, a resist pattern removal process is performed to remove the copper plating layer 26 directly under the resist pattern 40 and form the cover plating layer 29, whereby the mold shown in FIG. 12 is obtained.

[0061] In each of the above embodiments, as the material for forming each metal layer, in addition to nickel-cobalt, nickel, or a nickel alloy containing a metal other than cobalt, and further copper or a copper alloy can be applied. The substrate 1 may be a copper alloy material in addition to a stainless steel material. Further, in the substrate conditioning step of the above embodiment, a strike plating layer 20 is formed on the upper surface of the stainless steel substrate 1, and the first electroforming layer 21 or the first plating layer 51 is formed on the upper surface thereof. However, instead of forming the strike plating layer 20, the upper surface of the stainless steel substrate 1 can be subjected to a chemical etching treatment to serve as a base. The forming area 11 may be formed in a state of surrounding the dummy area 13. The concave structure 4 in the present invention does not necessarily have to be a recess closed by a bottom wall, and includes a form in which an opening is formed in the bottom wall of the recess. The forming projection 2 does not necessarily have to be formed by electroforming or plating, and can be formed by laser processing on a metal base material such as nickel, copper, or iron, or can be formed by etching the previous metal base material.

[0062] The mold according to the present invention can also be applied to plastic processing of a processing target other than the ceramic sheet.

Explanation of Reference Numerals

[0063] 1 Substrate 2 Forming projection 3 Ceramic sheet (processing target) 4 Loading recess (concave structure) 11 Forming area 13 Dummy area 14 Outer peripheral area 15 Dummy forming projection 20 Strike plating layer 21 First electroforming layer (metal layer) 22 Second electroforming layer (metal layer) 23 Third electroforming layer (metal layer) 26·27·28 Copper plating layer (intervening layer) 29 Cover plating layer (metal cover layer) 33·37 Photoresist layer 34·38 Photomask 35·39 Resist opening 36·40 Resist pattern 51 First plating layer (metal layer) 52 Second plating layer (metal layer)

Claims

1. A mold for plastic processing, which is configured by forming a molding convex portion (2) on the upper surface of a substrate (1), The forming convex portion (2) is composed of a plurality of metal layers laminated in multiple stages, and includes a first metal layer (21) formed on the upper surface of the substrate (1) and a second metal layer (22) formed on the upper surface of the first metal layer (21); An etched surface is provided in a region on the upper surface of the first metal layer (21) where the second metal layer (22) is to be formed; A mold for plastic working, characterized in that the upper surfaces of a plurality of metal layers are covered with a metal cover layer (29) via an intervening layer.

2. 2. The mold for plastic working according to claim 1, characterized in that the first metal layer (21) has an etched surface in an area where the intermediate layer is to be formed on the upper surface of the first metal layer (21).

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