Method for manufacturing a double-sided wiring circuit board and double-sided wiring circuit board

Abstract

The manufacturing method of a wiring circuit board (X1) (a double-sided wiring circuit board) includes a first step of preparing a laminate (Y1) and a second step. The laminate (Y1) includes a metal core layer (10), insulating layers (20, 50), and conductor layers (30, 60). The insulating layer (20) has adjacent region portions (22) and an opening portion (23). The insulating layer (50) includes a region portion (52) and an opening portion (53) adjacent to the region portion (52), and the region portion (52) has a portion that faces the region portion (22) in the thickness direction. The conductor layer (30) includes a wiring portion (31) and a conduction portion (32). The conductor layer (60) includes a wiring portion (61) and a conduction portion (62). In the second step, a via portion (12) is formed by a first etching process and a second etching process performed on the metal core layer (10) through the opening portions (23, 53). The periphery of the via portion (12) is surrounded by a gap (13), and the via portion (12) extends between the region portions (22, 52) and is connected to the conduction portions (32, 62).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a double-sided wiring circuit board and a double-sided wiring circuit board. Background Art

[0002] In a wiring circuit board, in order to increase the density of wiring, a structure in which circuits are provided on both sides of the board is sometimes adopted. In such a double-sided wiring circuit board, it is necessary to electrically connect the circuits on both sides. For example, in the manufacturing process of a double-sided wiring circuit board, it is necessary to form a conductive structure portion such as a via that penetrates a core layer located between the circuits on both sides in the final product in the thickness direction. Regarding the technology related to such a method for manufacturing a double-sided wiring circuit board, it is described in, for example, Patent Document 1 below.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-120968 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] When the core layer of a double-sided wiring circuit board is made of metal, for the above-described conductive structure portion for electrical connection between the circuits on both sides, conventionally, for example, it is necessary to form it while achieving insulation between it and the metal core layer by surrounding its periphery with an insulating film. However, in order to form such a conductive structure portion, a relatively large number of processes are required. In the manufacturing process of a double-sided wiring circuit board, from the viewpoint of manufacturing efficiency, a method that requires a plurality of processes in the formation process of its conductive structure portion is not ideal.

[0008] The present invention provides a method for manufacturing a double-sided wiring circuit board and a double-sided wiring circuit board suitable for efficiently manufacturing a double-sided wiring circuit board having a metal core layer.

[0009] Solutions to the Problems

[0010] The present invention [1] includes a method for manufacturing a double-sided wiring circuit board. The method for manufacturing the double-sided wiring circuit board includes: a first step, in which a laminate is prepared. The laminate includes a metal core layer, a first insulating layer, a first conductor layer, a second insulating layer, and a second conductor layer. The first insulating layer is disposed on one side in the thickness direction of the metal core layer and includes a first region portion having a first hole portion and at least one first opening portion adjacent to the first region portion. The first conductor layer has a first wiring portion and a first conduction portion. The first wiring portion is disposed at least on the first region portion on one side in the thickness direction of the first insulating layer. The first conduction portion is disposed in the first hole portion and is connected to the first wiring portion and the metal core layer. The second insulating layer is disposed on the other side in the thickness direction of the metal core layer and has a second region portion and at least one second opening portion adjacent to the second region portion. The second region portion includes a portion that is opposite to the first region portion in the thickness direction and has a second hole portion in this portion. The second conductor layer has a second wiring portion and a second conduction portion. The second wiring portion is disposed at least on the second region portion on the other side in the thickness direction of the second insulating layer. The second conduction portion is disposed in the second hole portion and is connected to the second wiring portion and the metal core layer; and a second step, in which, in this second step, a first etching process for the metal core layer is performed from one side in the thickness direction of the laminate through the first opening portion, and a second etching process for the metal core layer is performed from the other side in the thickness direction of the laminate through the second opening portion, so as to form a via portion in the metal core layer. The periphery of the via portion is surrounded by a void. The via portion extends in the thickness direction between the first region portion and the second region portion and is connected to the first conduction portion and the second conduction portion.

[0011] In this method, via holes are formed in the metal core layer by the first etching process and the second etching process as described above. The via holes electrically connect the first conductor layer on one side and the second conductor layer on the other side in the thickness direction of the double-sided wiring circuit board having the metal core layer, and are surrounded by voids. In such a method, there is no need to provide an insulating film or the like for insulating the via holes from other parts in the metal core layer. Therefore, this method is suitable for reducing the number of steps for forming via holes that electrically connect the first conductor layer and the second conductor layer during the manufacturing process of the double-sided wiring circuit board having a metal core layer. In addition, this method is suitable for performing etching for forming the outline (outline when observed in projection) of the metal core layer during the first etching process and the second etching process. Therefore, from this perspective, it is also suitable for reducing the number of steps. As described above, this manufacturing method suitable for reducing the number of steps is suitable for efficiently manufacturing a double-sided wiring circuit board having a metal core layer. In addition, according to this method of forming a conductive structure portion (via hole) that electrically connects the double-sided circuits by forming voids in the metal core layer, even when the metal core layer is thick, the double-sided circuits can be properly electrically connected.

[0012] The present invention [2] includes the method for manufacturing a double-sided wiring circuit board described in [1] above, wherein the first etching process and the second etching process are performed simultaneously.

[0013] Such a structure is suitable for reducing the number of steps during the manufacturing process of the double-sided wiring circuit board having a metal core layer, and thus is suitable for efficiently manufacturing a double-sided wiring circuit board having a metal core layer.

[0014] The present invention [3] includes the method for manufacturing a double-sided wiring circuit board described in [1] or [2] above, wherein when observed in projection along the thickness direction, the first opening and the second opening surround the first conduction portion and the second conduction portion in a connected manner.

[0015] The above structure in which the first opening and the second opening surround the first conduction portion and the second conduction portion in a connected manner when observed in projection along the thickness direction of the laminate is suitable for appropriately forming voids around the via holes in the metal core layer by the first etching process on the metal core layer via the first opening and the second etching process on the metal core layer via the second opening.

[0016] The present invention [4] includes the method for manufacturing a two-sided wiring circuit board according to any one of [1] to [3] above, wherein the laminate further includes: a third insulating layer that covers the first conductor layer on one side in the thickness direction of the first insulating layer and has a third opening that communicates with the first opening; and a fourth insulating layer that covers the second conductor layer on the other side in the thickness direction of the second insulating layer and has a fourth opening that communicates with the second opening.

[0017] Such a structure is suitable for performing the first etching process and the second etching process above without separately providing an etching mask for covering and protecting the first conductor layer and an etching mask for covering and protecting the second conductor layer, and thus is suitable for reducing the number of processes.

[0018] The present invention [5] includes a two-sided wiring circuit board, wherein the two-sided wiring circuit board includes: a metal core layer that includes a via portion surrounded by a void and a core layer main portion adjacent to the via portion across the void; a first insulating layer that is disposed on one side in the thickness direction of the metal core layer and includes a first region portion having a first hole portion and at least one first opening adjacent to the first region portion; a first conductor layer that has a first wiring portion and a first conduction portion, the first wiring portion is disposed at least on the first region portion on one side in the thickness direction of the first insulating layer, and the first conduction portion is disposed in the first hole portion and is connected to the first wiring portion and the metal core layer; a second insulating layer that is disposed on the other side in the thickness direction of the metal core layer and has a second region portion and at least one second opening adjacent to the second region portion, the second region portion includes a portion that is opposite to the first region portion in the thickness direction and has a second hole portion in this portion; and a second conductor layer that has a second wiring portion and a second conduction portion, the second wiring portion is disposed at least on the second region portion on the other side in the thickness direction of the second insulating layer, and the second conduction portion is disposed in the second hole portion and is connected to the second wiring portion and the metal core layer.

[0019] The two-sided wiring circuit board with such a structure is suitable for reducing the number of processes during its manufacturing process, and thus is suitable for efficient manufacturing.

[0020] The present invention [6] includes the two-sided wiring circuit board according to [5] above, wherein when observed in a projection along the thickness direction, the first opening and the second opening are connected to surround the first conduction portion and the second conduction portion.

[0021] When observed in a projection along the thickness direction of the double-sided wiring circuit board, the above structure in which the first opening and the second opening are connected to surround the first conduction part and the second conduction part is suitable for appropriately forming a gap around the via part in the metal core layer by a first etching process on the metal core layer through the first opening and a second etching process on the metal core layer through the second opening during the manufacturing process of the double-sided wiring circuit board. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 FIG. 6 is a cross-sectional view of a first embodiment of the double-sided wiring circuit board of the present invention.

[0023] Figure 2 FIG. Figure 1 12 is a partial top view of the double-sided wiring circuit board shown in FIG. 11.

[0024] Figure 3 FIG. Figure 1 18 is a partial bottom view of the double-sided wiring circuit board shown in FIG. 17.

[0025] Figure 4 FIG. Figure 2 24 and Figure 3 26 are cross-sectional views taken along line IV-IV in FIGS. 24 and 26.

[0026] Figure 5 FIG. Figure 1 32 shows the shapes of the first opening, the second opening, the first conduction part, and the second conduction part observed when the double-sided wiring circuit board shown in FIG. 31 is projected in the thickness direction.

[0027] Figure 6 FIG. Figure 1 38 is a partial top view of a modified example of the double-sided wiring circuit board shown in FIG. 37.

[0028] Figure 7 FIG. Figure 1 44 is a partial bottom view of a modified example of the double-sided wiring circuit board shown in FIG. 43.

[0029] Figure 8 FIG. Figure 6 50 and Figure 7 52 shows the shapes of the first opening, the second opening, the first conduction part, and the second conduction part observed when the double-sided wiring circuit board shown in FIGS. 50 and 52 is projected in the thickness direction.

[0030] Figure 9 FIG. Figure 1 58 is a cross-sectional view of another modified example of the double-sided wiring circuit board shown in FIG. 57.

[0031] Figure 10 In FIG. Figure 10 64, A is Figure 1 a partial bottom view of another modified example of the double-sided wiring circuit board shown in FIG. 65.Figure 10 in Figure 10 B is Figure 1 a partial bottom view in another modified example of the double-sided wiring circuit board shown.

[0032] Figure 11 Represented by a change in the cross-section corresponding to Figure 1 a part of the process in the manufacturing method of the double-sided wiring circuit board of the first embodiment. Figure 11 A represents a preparation process, Figure 11 B represents a first base insulating layer formation process, Figure 11 C represents a first conductor layer formation process, Figure 11 D represents a first cover insulating layer formation process.

[0033] Figure 12 Represents the process carried out subsequently after the process shown in Figure 11 the figure. Figure 12 A represents a second base insulating layer formation process, Figure 12 B represents a second conductor layer formation process, Figure 12 C represents a second cover insulating layer formation process, Figure 12 D represents an etching process.

[0034] Figure 13 Represented by a change in the cross-section corresponding to Figure 4 a part of the process in the manufacturing method of the double-sided wiring circuit board of the first embodiment. Figure 13 A represents a preparation process, Figure 13 B represents a first base insulating layer formation process, Figure 13 C represents a first conductor layer formation process, Figure 13 D represents a first cover insulating layer formation process.

[0035] Figure 14 Represents the process carried out subsequently after the process shown in Figure 13 the figure. Figure 14 A represents a second base insulating layer formation process, Figure 14 B represents a second conductor layer formation process, Figure 14 C represents a second cover insulating layer formation process, Figure 14 D represents an etching process.

[0036] Figure 15 Represents an intermediate product, i.e., a laminate, in a modified example of the manufacturing method of the double-sided wiring circuit board of the first embodiment. Figure 15 A represents a cross-section corresponding to the cross-section shown in Figure 1 the figure, Figure 15 B represents a cross-section corresponding to the cross-section shown in Figure 4 the figure.

[0037] Figure 16 Indicates the shapes of the first opening, the second opening, the first conduction part, and the second conduction part observed when the laminated body shown in Figure 15 is projected in the thickness direction.

[0038] Figure 17 Indicates the etching process in a modification of the manufacturing method of the double-sided wiring circuit board according to the first embodiment. Figure 17 A indicates the cross-section corresponding to the cross-section shown in Figure 15 A, Figure 17 B indicates the cross-section corresponding to the cross-section shown in Figure 15 B.

[0039] Figure 18 Is a cross-sectional view of the second embodiment of the double-sided wiring circuit board of the present invention.

[0040] Figure 19 Is Figure 18 A partial top view of the double-sided wiring circuit board shown.

[0041] Figure 20 Is Figure 18 A partial bottom view of the double-sided wiring circuit board shown.

[0042] Figure 21 Is a partial cross-sectional view along the XXI-XXI line in Figure 19 and Figure 20 .

[0043] Figure 22 Indicates the shapes of the first opening, the second opening, the first conduction part, and the second conduction part observed when the double-sided wiring circuit board shown in Figure 18 is projected in the thickness direction.

[0044] Figure 23 Represents part of the process in the manufacturing method of the double-sided wiring circuit board according to the second embodiment with a change equivalent to the cross-section of Figure 18 . Figure 23 A indicates the preparation process, Figure 23 B indicates the first base insulating layer formation process, Figure 23 C indicates the first conductor layer formation process, Figure 23 D indicates the first cover insulating layer formation process.

[0045] Figure 24 Indicates the process that follows after the process shown in Figure 23 . Figure 24 A indicates the second base insulating layer formation process, Figure 24 B indicates the second conductor layer formation process, Figure 24 C indicates the second cover insulating layer formation process, Figure 24D represents an etching process.

[0046] Figure 25 In terms of Figure 21 the change in the cross-section equivalent to Figure 25 A represents a preparation process, Figure 25 B represents the first base insulating layer formation process, Figure 25 C represents the first conductor layer formation process, Figure 25 D represents the first covering insulating layer formation process.

[0047] Figure 26 represents the process that follows after the process shown in Figure 25 the process shown in Figure 26 A represents the second base insulating layer formation process, Figure 26 B represents the second conductor layer formation process, Figure 26 C represents the second covering insulating layer formation process, Figure 26 D represents the etching process.

[0048] Figure 27 represents an intermediate laminate used in a modified example of the manufacturing method of the double-sided wiring circuit board according to the second embodiment. Figure 27 A represents a cross-section corresponding to the cross-section shown in Figure 18 the cross-section shown in Figure 27 B represents a cross-section corresponding to the cross-section shown in Figure 21 the cross-section shown in Detailed implementation mode

[0049] Figures 1 to 4 represents the wiring circuit board X1 of the first embodiment of the present invention. Figure 1 is a schematic cross-sectional view showing the wiring circuit board X1. Figure 2 is a partial top view of the wiring circuit board X1 (wherein, the insulating layer 40 described later is omitted). Figure 3 is a partial bottom view of the wiring circuit board X1 (wherein, the insulating layer 70 described later is omitted). Figure 4 is a cross-sectional view along the Figure 2 and Figure 3 IV-IV line in

[0050] The wiring circuit board X1 is a double-sided wiring circuit board, and includes a metal core layer 10, insulating layers 20, 40, 50, 70, and conductor layers 30, 60.

[0051] As Figure 1 shown, the metal core layer 10 has a core layer main part 11 and a via part 12. The core layer main part 11 is a component for ensuring the rigidity of the wiring circuit board X1. The via part 12 is a component for electrically connecting the circuits on both sides of the wiring circuit board X1. AsFigure 1 and Figure 4 As shown in Figure 4 , the periphery of the passage portion 12 is surrounded by the gap 13. The passage portion 12 and the core layer main body portion 11 are adjacent to each other with the gap 13 therebetween. Specifically, the core layer main body portion 11 has a plate shape, and a cylindrical gap 13 is formed in the core layer main body portion 11. And, the cylindrical passage portion 12 is disposed in the gap 13 at a distance from the core layer main body portion 11. The separation distance between the passage portion 12 and the core layer main body portion 11 is, for example, 10 μm or more, preferably 15 μm or more. The passage portion 12 is insulated from the core layer main body portion 11 by being surrounded by such a gap 13.

[0052] As the constituent material of the metal core layer 10, for example, Cu, Cu alloy, stainless steel, and 42 alloy (42Alloy) can be cited. From the viewpoints of thermal conductivity and electrical conductivity, Cu and Cu alloy are preferably selected.

[0053] The thickness of the metal core layer 10 is, for example, 10 μm or more, preferably 15 μm or more, and for example, 500 μm or less, preferably 300 μm or less.

[0054] As Figure 1 and Figure 4 shown in Figure 4 , the insulating layer 20 (first insulating layer) is a base insulating layer disposed on one side in the thickness direction of the metal core layer 10, and has a pattern shape including a main body portion 21, a region portion 22 (first region portion), and a plurality of (in the present embodiment, two with respect to one region portion 22) opening portions 23 (first opening portions). The opening portions 23 are adjacent to the region portion 22 and are interposed between the main body portion 21 and the region portion 22.

[0055] The main body portion 21 overlaps with the core layer main body portion 11 when observed in projection along the thickness direction (hereinafter sometimes simply referred to as "when observed in projection").

[0056] The region portion 22 has an inner portion 22a and a plurality of connecting portions 22b.

[0057] When observed in projection, the inner portion 22a overlaps with the passage portion 12 and contacts one end in the thickness direction of the passage portion 12. In the present embodiment, the inner portion 22a has a circular shape. In the inner portion 22a, the region portion 22 has a hole portion 22c. At the central portion of the inner portion 22a when observed in projection, the hole portion 22c penetrates the inner portion 22a in the thickness direction of the inner portion 22a.

[0058] The connecting portion 22b connects the inner portion 22a and the main body portion 21. The connecting portion 22b is a portion that overlaps with the opening portion 53 described later and does not overlap with the connecting portion 52b described later when viewed in projection, and a plurality of them (in the present embodiment, two are arranged in one region portion 22) are arranged so as to sandwich the inner portion 22a. Each connecting portion 22b has a strip shape with one end connected to the inner portion 22a and the other end connected to the main body portion 21.

[0059] The opening portion 23 functions as an etching window in the etching process of the metal core layer 10 during the manufacturing process of the wiring circuit board X1 described later, and penetrates the insulating layer 20 in the thickness direction of the insulating layer 20. In the present embodiment, two opening portions 23 are arranged sandwiching the region portion 22. Further, in the present embodiment, as Figure 2 shown, each opening portion 23 has a fan shape, and the region portion 22 and the two opening portions 23 together form a shape that is substantially circular when viewed in projection.

[0060] As a constituent material of the insulating layer 20, for example, synthetic resins such as polyimide, polyether nitrile, polyether sulfone, polyethylene terephthalate, polyethylene naphthalate, and polyvinyl chloride can be cited, and photosensitive polyimide is preferably used (the same applies to the constituent materials of the insulating layers 40, 50, and 70 described later).

[0061] The thickness of the insulating layer 20 is, for example, 1 μm or more, preferably 3 μm or more, and for example, 35 μm or less, preferably 20 μm or less.

[0062] As Figure 1 and Figure 4 shown, the conductor layer 30 (first conductor layer) includes a conduction portion 32 (first conduction portion) and a wiring portion 31 (first wiring portion) having a predetermined pattern shape arranged on one side in the thickness direction of the insulating layer 20. In the present embodiment, the wiring portion 31 is arranged so as to straddle the main body portion 21 and the region portion 22 of the insulating layer 20. Specifically, as Figure 2 shown, one end of the wiring portion 31 is arranged on the inner portion 22a, the wiring portion 31 passes through the connecting portion 22b and extends outside the region portion 22. The conduction portion 32 is arranged in the hole portion 22c of the insulating layer 20, and the conduction portion 32 is connected to the wiring portion 31 and connected to one end in the thickness direction of the through hole portion 12 of the metal core layer 10.

[0063] As a constituent material of the conductor layer 30, for example, metal materials such as copper, nickel, gold, solder, or their alloys can be cited, and copper is preferably selected (the same applies to the constituent materials of the conductor layer 60 described later).

[0064] The thickness of the conductor layer 30 is, for example, 3 μm or more, preferably 5 μm or more, and for example, 50 μm or less, preferably 30 μm or less.

[0065] The insulating layer 40 (third insulating layer) is a covering insulating layer disposed on one side in the thickness direction of the insulating layer 20 so as to cover the conductor layer 30, and has a pattern shape with an opening 41 (third opening). The opening 41 overlaps with the opening 23 of the insulating layer 20 and communicates with the opening 23 when viewed in projection. In the present embodiment, the opening 41 has the same or substantially the same opening shape as the opening 23. The opening 41 can function as an etching window in an etching process for the metal core layer 10 in a manufacturing process of the wiring circuit board X1 described later.

[0066] As long as the thickness of the insulating layer 40 (height from the insulating layer 20) is within a range greater than the thickness of the conductor layer 30, it is, for example, 4 μm or more, preferably 6 μm or more, and for example, 60 μm or less, preferably 40 μm or less.

[0067] As Figure 1 and Figure 4 shown, the insulating layer 50 (second insulating layer) is a base insulating layer disposed on the other side in the thickness direction of the metal core layer 10, and has a pattern shape including a main part 51, a region part 52 (second region part), and a plurality of (in the present embodiment, two are disposed with respect to one region part 52) openings 53 (second openings). The openings 53 are adjacent to the region part 52 and are interposed between the main part 51 and the region part 52.

[0068] The main part 51 overlaps with the core layer main part 11 when viewed in projection.

[0069] The region part 52 has an inner part 52a and a plurality of connecting parts 52b.

[0070] The inner part 52a overlaps with the via part 12 and contacts the other end in the thickness direction of the via part 12 when viewed in projection, and has a circular shape in the present embodiment. In addition, the inner part 52a faces the inner part 22a of the above-mentioned region part 22 in the thickness direction. In the inner part 52a, the region part 52 has a hole part 52c. At the central part of the inner part 52a when viewed in projection, the hole part 52c penetrates the inner part 52a in the thickness direction of the inner part 52a.

[0071] The connecting portion 52b connects the inner portion 52a and the main body portion 51. The connecting portion 52b is a portion that overlaps the opening portion 23 and does not overlap the connecting portion 22b in the projection view, and a plurality of them (in this embodiment, two are arranged in one region portion 52) are arranged so as to sandwich the inner portion 52a. Each connecting portion 52b has a strip shape with one end connected to the inner portion 52a and the other end connected to the main body portion 51. The direction in which the connecting portion 52b extends and the direction in which the connecting portion 22b extends cross (orthogonal in this embodiment) in the projection view.

[0072] The opening portion 53 is an opening portion that functions as an etching window in the etching process of the metal core layer 10 during the subsequent manufacturing process of the wiring circuit board X1, and penetrates the insulating layer 50 in the thickness direction of the insulating layer 50. In this embodiment, two opening portions 53 are arranged sandwiching the region portion 52. Further, in this embodiment, as Figure 3 shown, each opening portion 53 has a fan shape, and the region portion 52 and the two opening portions 53 together form a shape that is substantially circular in the projection view.

[0073] The thickness of the insulating layer 50 is, for example, 1 μm or more, preferably 3 μm or more, and for example, 35 μm or less, preferably 20 μm or less.

[0074] As Figure 1 and Figure 4 shown, the conductor layer 60 (second conductor layer) includes a conduction portion 62 (second conduction portion) and a wiring portion 61 (second wiring portion) having a predetermined pattern shape arranged on the other side in the thickness direction of the insulating layer 50. In this embodiment, the wiring portion 61 is arranged straddling the main body portion 51 and the region portion 52 of the insulating layer 50. Specifically, as Figure 3 shown, one end of the wiring portion 61 is arranged on the inner portion 52a, and the wiring portion 61 passes through the connecting portion 52b and extends outside the region portion 52. The conduction portion 62 is arranged in the hole portion 52c of the insulating layer 50, and the conduction portion 62 is connected to the wiring portion 61 and connected to the other end in the thickness direction of the through-hole portion 12 of the metal core layer 10.

[0075] The thickness of the conductor layer 60 is, for example, 3 μm or more, preferably 5 μm or more, and for example, 50 μm or less, preferably 30 μm or less.

[0076] The insulating layer 70 (the fourth insulating layer) is a covering insulating layer disposed on the other side in the thickness direction of the insulating layer 50 so as to cover the conductor layer 60, and has a pattern shape with an opening 71 (the fourth opening). The opening 71 overlaps with the opening 53 of the insulating layer 50 and communicates with the opening 53 when viewed in projection. In the present embodiment, the opening 71 has the same or substantially the same opening shape as the opening 53. The opening 71 can function as an etching window in an etching process for the metal core layer 10 in a manufacturing process of the wiring circuit board X1 described later.

[0077] The thickness of the insulating layer 70 (the height from the insulating layer 50) is, for example, 4 μm or more, preferably 6 μm or more, and for example, 60 μm or less, preferably 40 μm or less, as long as it is in a range greater than the thickness of the conductor layer 60.

[0078] In the wiring circuit board X1, as Figure 5 shown, when viewed in projection along the thickness direction of the wiring circuit board X1, the opening 23 of the insulating layer 20 and the opening 53 of the insulating layer 50 surround the conduction portions 32, 62 in a connected manner (in Figure 5 , the shape of the opening 53 is indicated by a dotted line, and the shapes of the opening 23 and the conduction portions 32, 62 are indicated by solid lines). In the present embodiment, when viewed in the above projection, the openings 23, 53 form an annular shape in a connected manner. In addition, when viewed in projection along the thickness direction of the wiring circuit board X1, the opening 23 and the opening 53 surround the passage portion 12 in a connected manner. In the present embodiment, the openings 23, 53 are provided in such an opening shape (as described above, the opening 41 of the insulating layer 40 has the same or substantially the same opening shape as the opening 23, and the opening 71 of the insulating layer 70 has the same or substantially the same opening shape as the opening 53).

[0079] In the wiring circuit board X1, it is also possible that the insulating layer 20 has a pattern shape including a region portion 22 having a projection shape as shown in Figure 6 and the opening 23, and the insulating layer 50 has a pattern shape including a region portion 52 having a projection shape as shown in Figure 7 (including a portion opposite to the region portion 22 in the thickness direction) and the opening 53 (the opening 41 of the insulating layer 40 has the same or substantially the same opening shape as the opening 23, which is omitted in Figure 6 . The opening 71 of the insulating layer 70 has the same or substantially the same opening shape as the opening 53, which is omitted in Figure 7(Omitted). In this modified example, in the region portion 22, a substantially rectangular shape is formed by the inner portion 22a and the connecting portion 22b. Each opening portion 23 sandwiching such a region portion 22 also has a substantially rectangular shape, and the region portion 22 and the two opening portions 23 together form a shape that is substantially rectangular when viewed in projection. Similarly, in this modified example, in the region portion 52, a substantially rectangular shape is formed by the inner portion 52a and the connecting portion 52b. Each opening portion 53 sandwiching such a region portion 52 also has a substantially rectangular shape, and the region portion 52 and the two opening portions 53 together form a shape that is substantially rectangular when viewed in projection. And, in this modified example, as Figure 8 shown, when viewed in projection along the thickness direction of the wiring circuit board X1, the opening portion 23 of the insulating layer 20 and the opening portion 53 of the insulating layer 50 are connected to form a rectangular frame shape and surround the conduction portions 32, 62. Further, when viewed in projection along the thickness direction of the wiring circuit board X1, the opening portion 23 of the insulating layer 20 and the opening portion 53 of the insulating layer 50 are connected to surround the via portion 12.

[0080] In the wiring circuit board X1, for example, as Figure 9 shown, the conduction portion 32 of the conductor layer 30 and the conduction portion 62 of the conductor layer 60 may also be arranged to be displaced from each other in the in-plane direction orthogonal to the thickness direction. In such a structure, electrical connection between the conductor layers 30, 60 can also be achieved through the via portion 12.

[0081] In the wiring circuit board X1, one of the wiring portion 31 connected to the conduction portion 32 of the conductor layer 30 and the wiring portion 61 connected to the conduction portion 62 of the conductor layer 60 may also be an electrode pad portion. When the wiring portion 31 connected to the conduction portion 32 of the conductor layer 30 is an electrode pad portion, a predetermined opening portion for exposing the electrode pad portion to the outside is provided in the insulating layer 40. When the wiring portion 61 connected to the conduction portion 62 of the conductor layer 60 is an electrode pad portion, a predetermined opening portion for exposing the electrode pad portion to the outside is provided in the insulating layer 70. Figure 10 A and Figure 10 B respectively illustratively show the case where the wiring portion 61 connected to the conduction portion 62 of the conductor layer 60 is the electrode pad portion 61A (wherein the insulating layer 70 is omitted). In Figure 10 the modified example shown in B, in the insulating layer 50, the region portion 52 is separated from the main portion 51.

[0082] Figures 11 to 14 Shows a manufacturing method of the wiring circuit board X1. Figure 11 and Figure 12 represent this manufacturing method with a change in the cross-section corresponding to Figure 1 , Figure 13 and Figure 14 represent this manufacturing method with a change in the cross-section corresponding to Figure 4The cross-sectional change is used to represent this manufacturing method.

[0083] In this manufacturing method, first, as Figure 11 A and Figure 13 shown in A, a metal core layer 10 is prepared (preparation process).

[0084] Next, as Figure 11 B and Figure 13 shown in B, an insulating layer 20 as a base insulating layer is formed on the metal core layer 10 (first base insulating layer formation process). In this process, for example, the insulating layer 20 is formed as follows. First, a solution (varnish) containing a photosensitive resin for forming the insulating layer 20 is applied to one surface of the metal core layer 10 in the thickness direction and dried to form an insulating film. Next, the insulating film is patterned. Specifically, for this insulating film, an exposure process performed through a predetermined mask, a subsequent development process, and a subsequent baking process as needed are carried out. For example, an insulating layer 20 including a hole portion 22c and an opening portion 23 that partially expose the metal core layer 10 can be formed on the metal core layer 10 as described above.

[0085] Next, as Figure 11 C and Figure 13 shown in C, a conductor layer 30 is formed on the insulating layer 20 (first conductor layer formation process). In this process, for example, the conductor layer 30 is formed as follows. First, on one surface of the insulating layer 20 in the thickness direction and the surface of the metal core layer 10 in the thickness direction that is not covered by the insulating layer 20, a thin seed layer (not shown) as an energization layer for forming an electroplated film is formed, for example, by sputtering. Examples of the constituent material of the seed layer include copper, chromium, nickel, and their alloys. Next, a resist pattern is formed on the seed layer. The resist pattern has an opening portion corresponding to the pattern shape of the conductor layer 30. During the formation of the resist pattern, for example, after a photosensitive resist film is attached to the seed layer to form a resist film, an exposure process performed through a predetermined mask, a subsequent development process, and a subsequent baking process as needed are carried out for this resist film. Next, during the formation of the conductor layer 30, a metal material is grown on the seed layer in the region within the opening portion of the resist pattern by electroplating. Copper is preferably used as the metal material. Next, the resist pattern is removed by etching. Next, the portion of the seed layer that is exposed due to the removal of the resist pattern is removed by etching. For example, a conductor layer 30 including a wiring portion 31 and a conduction portion 32 can be formed as described above.

[0086] In this manufacturing method, next, as Figure 11 D and Figure 13As shown in D, on one side in the thickness direction of the insulating layer 20, an insulating layer 40 (first covering insulating layer forming step) is formed so as to cover the conductor layer 30. In this step, for example, the insulating layer 40 is formed as follows. First, a solution (varnish) of a photosensitive resin for forming the insulating layer 40 is applied to the surface on one side in the thickness direction of the insulating layer 20 and the conductor layer 30 and dried to form an insulating film. Next, the insulating film is patterned. Specifically, for this insulating film, an exposure process performed through a predetermined mask, a development process performed thereafter, and a baking process performed as needed thereafter are carried out. For example, the insulating layer 40 having a predetermined pattern including the opening 41 can be formed as described above.

[0087] Next, as Figure 12 shown in Figure 14 A, on the metal core layer 10, an insulating layer 50 (second base insulating layer forming step) is formed as a base insulating layer. In this step, for example, the insulating layer 50 is formed as follows. First, a solution (varnish) of a photosensitive resin for forming the insulating layer 50 is applied to the surface on the other side in the thickness direction of the metal core layer 10 and dried to form an insulating film. Next, the insulating film is patterned. Specifically, for this insulating film, an exposure process performed through a predetermined mask, a development process performed thereafter, and a baking process performed as needed thereafter are carried out. For example, an insulating layer 50 having a predetermined pattern including the hole 52c that partially exposes the metal core layer 10 and the opening 53 can be formed on the surface on the other side in the thickness direction of the metal core layer 10 as described above.

[0088] Next, as Figure 12 shown in B and Figure 14As shown in FIG. B, a conductor layer 60 is formed on the insulating layer 50 (second conductor layer forming step). In this step, for example, the conductor layer 60 is formed as follows. First, on the surface of the other side in the thickness direction of the insulating layer 50 and on the surface of the other side in the thickness direction of the metal core layer 10 that is not covered by the insulating layer 50, a thin seed layer (not shown), which is an energization layer for electroplating film formation, is formed, for example, by sputtering. Next, a resist pattern is formed on the seed layer. The resist pattern has an opening corresponding to the pattern shape of the conductor layer 60. In the process of forming the resist pattern, for example, after a photosensitive resist film is attached to the seed layer to form a resist film, an exposure process performed through a predetermined mask, a subsequent development process, and a subsequent baking process as needed are performed on the resist film. In the process of forming the conductor layer 60, next, by electroplating, a metal material grows on the seed layer in the region within the opening of the resist pattern. As the metal material, copper is preferably used. Next, the resist pattern is removed by etching. Next, the portion of the seed layer that is exposed due to the removal of the resist pattern is removed by etching. For example, the conductor layer 60 having a predetermined pattern including a wiring portion 61 and a conduction portion 62 can be formed as described above.

[0089] In this manufacturing method, next, as Figure 12 shown in FIGS. C and Figure 14 C, on the other side in the thickness direction of the insulating layer 50, an insulating layer 70, which is a covering insulating layer, is formed so as to cover the conductor layer 60 (second covering insulating layer forming step). In this step, for example, the insulating layer 70 is formed as follows. First, a solution (varnish) of a photosensitive resin for forming the insulating layer 70 is applied to the surface of the other side in the thickness direction of the insulating layer 50 and the conductor layer 60 and dried to form an insulating film. Next, the insulating film is patterned. Specifically, for the insulating film, an exposure process performed through a predetermined mask, a subsequent development process, and a subsequent baking process as needed are performed. For example, the insulating layer 70 having a predetermined pattern including an opening 71 can be formed as described above.

[0090] In the present embodiment, through the above-described respective processes, a laminate Y1 is obtained as an intermediate product. The laminate Y1 includes a metal core layer 10 in which the above-described core layer main body portion 11 and via portion 12 have not yet been formed, an insulating layer 20 disposed on one side in the thickness direction of the metal core layer 10, a conductor layer 30 and an insulating layer 40, and an insulating layer 50, a conductor layer 60 and an insulating layer 70 disposed on the other side in the thickness direction of the metal core layer 10. The insulating layer 20 in the laminate Y1 includes a region portion 22 having a hole portion 22c and at least one opening portion 23 adjacent to the region portion 22. The conductor layer 30 in the laminate Y1 includes: a wiring portion 31 disposed at least on the region portion 22 on one side in the thickness direction of the insulating layer 20; and a conduction portion 32 disposed in the hole portion 22c and connected to the wiring portion 31 and the metal core layer 10. The insulating layer 40 in the laminate Y1 covers the conductor layer 30 on one side in the thickness direction of the insulating layer 20, and has an opening portion 41 communicating with the opening portion 23 of the insulating layer 20. The insulating layer 50 in the laminate Y1 has a region portion 52 and at least one opening portion 53 adjacent to the region portion 52, and the region portion 52 includes a portion opposed to the region portion 22 of the insulating layer 20 in the thickness direction and has a hole portion 52c in this portion. The conductor layer 60 in the laminate Y1 includes: a wiring portion 61 disposed at least on the region portion 52 on the other side in the thickness direction of the insulating layer 50; and a conduction portion 62 disposed in the hole portion 52c and connected to the wiring portion 61 and the metal core layer 10. The insulating layer 70 in the laminate Y1 covers the conductor layer 60 on the other side in the thickness direction of the insulating layer 50, and has an opening portion 71 communicating with the opening portion 53 of the insulating layer 50. Further, in the laminate Y1, as described above with reference to Figure 5 the wiring circuit board X1, when viewed in projection along the thickness direction, the opening portion 23 of the insulating layer 20 and the opening portion 53 of the insulating layer 50 are connected to surround the conduction portions 32 and 62 (the opening portion 41 of the insulating layer 40 has the same or substantially the same opening shape as the opening portion 23, and the opening portion 71 of the insulating layer 70 has the same or substantially the same opening shape as the opening portion 53).

[0091] In the present manufacturing method, next, as shown in Figure 12 D and Figure 14 D, by performing an etching process on the metal core layer 10, a core layer main body portion 11 and a via portion 12 are formed in the metal core layer 10 (etching process). As the etching solution for the etching process, for example, ferric chloride is used.

[0092] The etching process in this step includes a first etching process and a second etching process. The first etching process is an etching process for the metal core layer 10 through the openings 23 and 41 of the insulating layers 20 and 40 from one side in the thickness direction of the laminate Y1. The second etching process is an etching process for the metal core layer 10 through the openings 53 and 71 from the other side in the thickness direction of the laminate Y1. In this step, the first etching process and the second etching process can be implemented simultaneously, or the second etching process can be implemented after the end of the first etching process, or the first etching process can be implemented after the end of the second etching process. Preferably, the first etching process and the second etching process are implemented simultaneously. Through such an etching process, a via portion 12 surrounded by a gap 13 can be formed in the metal core layer 10 (the via portion 12 extends in the thickness direction between the region portion 22 of the insulating layer 20 and the region portion 52 of the insulating layer 50 and is connected to the conduction portions 32 and 62).

[0093] In the laminate Y1, when observed in projection along its thickness direction, the openings 23 and 41 of the insulating layers 20 and 40 and the openings 53 and 71 of the insulating layers 50 and 70 surround the conduction portions 32 and 62 in a connected manner. According to such a structure, in the etching process, through the above-mentioned first etching process for the metal core layer 10 through the openings 23 and 41 and the second etching process for the metal core layer 10 through the openings 53 and 71, a gap 13 surrounding the periphery of the via portion 12 can be appropriately formed in the metal core layer 10.

[0094] In addition, in this embodiment, preferably, the etching process for forming the contour of the metal core layer 10 (the contour when observed in projection) is also performed by the first etching process and the second etching process. Thereby, the formation of the via portion 12 of the metal core layer 10 and the formation of the contour of the metal core layer 10 can be implemented in parallel. However, it may also be that, in addition to the above-mentioned etching process for forming the via portion 12, an etching process for forming the contour of the metal core layer 10 is implemented.

[0095] As described above, a wiring circuit board X1 having a via portion 12 formed in the metal core layer 10 can be manufactured.

[0096] In this manufacturing method, via portions 12 are formed in the metal core layer 10 by the first etching process and the second etching process as described above. The via portions 12 electrically connect the conductor layer 30 on one side in the thickness direction of the wiring circuit board X1 having the metal core layer 10 and the conductor layer 60 on the other side, and are surrounded by voids 13. By adopting such a method, there is no need to provide an insulating film or the like for insulating the via portions 12 from other portions in the metal core layer 10. Therefore, this method is suitable for reducing the number of steps for forming the via portions 12 that electrically connect the conductor layers 30 and 60 during the manufacturing process of the wiring circuit board X1 having the metal core layer 10. In addition, this method is suitable for performing etching for forming the profile of the metal core layer 10 in the first etching process and the second etching process, and thus is suitable for reducing the number of steps. As described above, this manufacturing method suitable for reducing the number of steps is suitable for efficiently manufacturing the wiring circuit board X1 having the metal core layer 10.

[0097] In addition, according to this method of forming a conductive structure portion (via portion 12) that electrically connects the two-sided circuits by forming voids 13 in the metal core layer 10, even when the metal core layer 10 is thick, the two-sided circuits can be properly electrically connected.

[0098] In the present embodiment, as described above, it is preferable to perform the first etching process and the second etching process simultaneously. Such a structure is suitable for reducing the number of steps during the manufacturing process of the wiring circuit board X1 having the metal core layer 10, and thus is suitable for efficiently manufacturing the wiring circuit board X1.

[0099] In the present embodiment, as described above, the laminate Y1 to which Figure 12 D and Figure 14 D shown in the etching process is applied includes an insulating layer 40 (covering the conductor layer 30 on one side in the thickness direction of the insulating layer 20 and having an opening 41 that communicates with the opening 23 of the insulating layer 20 and functions as an etching window) and an insulating layer 70 (covering the conductor layer 60 on the other side in the thickness direction of the insulating layer 50 and having an opening 71 that communicates with the opening 53 of the insulating layer 50 and functions as an etching window). Such a structure is suitable for performing the first etching process and the second etching process without separately providing an etching mask for covering and protecting the conductor layer 30 and an etching mask for covering and protecting the conductor layer 60, and thus is suitable for reducing the number of steps.

[0100] In the manufacturing method of the wiring circuit board X1, it may also be, as Figure 15 A and Figure 15 B shown, to use a laminate Y2 provided with resist masks 101 and 102 instead of the insulating layers 40 and 70, and perform the etching process on the metal core layer 10 ( Figure 15 A represents Figure 1The cross-section corresponding to the cross-section shown Figure 15 B represents the one corresponding to Figure 4 the cross-section shown). As Figure 16 shown, in the laminate Y2, when viewed in projection along its thickness direction, the opening 23 of the insulating layer 20 and the opening 53 of the insulating layer 50 are connected to form an annular shape and surround the conduction portions 32 and 62. Further, as Figure 15 shown, in the laminate Y2, the resist mask 101 is disposed on one side in the thickness direction of the insulating layer 20 so as to cover the conductor layer 30, and has a pattern shape with an opening 101a. The opening 101a communicates with the opening 23 and has the same or substantially the same opening shape as the opening 23. The resist mask 102 is disposed on the other side in the thickness direction of the insulating layer 50 so as to cover the conductor layer 60, and has a pattern shape with an opening 102a. The opening 102a communicates with the opening 53 and has the same or substantially the same opening shape as the opening 53.

[0101] The laminate Y2 is obtained, for example, through the above-described preparation process( Figure 11 A, Figure 13 A), the first insulating layer formation process( Figure 11 B, Figure 13 B), the subsequent first conductor layer formation process( Figure 11 C, Figure 13 C), the second insulating layer formation process( Figure 12 A, Figure 14 A), the subsequent second conductor layer formation process( Figure 12 B, Figure 14 B), the first resist mask formation process for forming the resist mask 101 after the first conductor layer formation process, and the second resist mask formation process for forming the resist mask 102 after the second conductor layer formation process. In the first resist mask formation process, the resist mask 101 can be formed, for example, by patterning a photosensitive resist film disposed on one side in the thickness direction of the insulating layer 20 so as to cover the conductor layer 30. In the second resist mask formation process, the resist mask 102 can be formed, for example, by patterning a photosensitive resist film disposed on the other side in the thickness direction of the insulating layer 50 so as to cover the conductor layer 60.

[0102] And, in the etching process in this modification, using such a laminate Y2, the first etching process and the second etching process for the metal core layer 10 are performed. As Figure 17 A and Figure 17 B show, the core layer main portion 11 and the via portion 12 are formed in the metal core layer 10( Figure 17 A represents the cross-section corresponding to Figure 15 the cross-section shown in A, Figure 17 B represents the one corresponding toFigure 15 The cross-section corresponding to the cross-section shown in B).

[0103] The first etching process in this modification is an etching process for the metal core layer 10 from one side in the thickness direction of the laminate Y2 through the opening 23 of the insulating layer 20 and the opening 101a of the resist mask 101. The second etching process in this modification is an etching process for the metal core layer 10 from the other side in the thickness direction of the laminate Y2 through the opening 53 of the insulating layer 50 and the opening 102a of the resist mask 102. In this step, the first etching process and the second etching process can be carried out simultaneously, the second etching process can be carried out after the end of the first etching process, and the first etching process can also be carried out after the end of the second etching process. From the viewpoint of reducing the number of processes, it is preferable to carry out the first etching process and the second etching process simultaneously. Through such an etching process, a via portion 12 surrounded by voids 13 can be formed in the metal core layer 10 (the via portion 12 extends in the thickness direction between the region portion 22 of the insulating layer 20 and the region portion 52 of the insulating layer 50 and is connected to the conduction portions 32 and 62).

[0104] After the etching process, the resist masks 101 and 102 are removed from the laminate Y2.

[0105] By going through the above process, a wiring circuit board X1 having a metal core layer 10 including a via portion 12 surrounded by voids 13 can also be manufactured. In this method, the same effects as those of the first embodiment can be obtained.

[0106] In addition, in this method, if necessary, as described above with reference to Figure 11 D and Figure 13 D, an insulating layer 40 (first covering insulating layer forming step) covering the insulating layer is formed, and as described above with reference to Figure 12 C and Figure 14 C, an insulating layer 70 (second covering insulating layer forming step) covering the insulating layer is formed.

[0107] Figures 18 to 21 A wiring circuit board X2 showing the second embodiment of the present invention. Figure 18 It is a cross-sectional view schematically showing the wiring circuit board X2. Figure 19 It is a partial top view of the wiring circuit board X2 (wherein the insulating layer 40 is omitted). Figure 20 It is a partial bottom view of the wiring circuit board X2 (wherein the insulating layer 70 is omitted). Figure 21 It is along Figure 19 and Figure 20 A partial cross-sectional view taken along the line XXI-XXI.

[0108] For the wiring circuit board X2, except for the following description, the other contents are the same as those of the wiring circuit board X1, and the same reference numerals are used for the same components.

[0109] In the metal core layer 10 of the wiring circuit board X2, the via portion 12 is located at a predetermined end portion in the projected shape of the metal core layer 10.

[0110] In the insulating layer 20 of the wiring circuit board X2, the region portion 22 and the opening portion 23 are also located at the above-mentioned predetermined end portion corresponding to the formation position of the via portion 12.

[0111] As Figure 19 shown, the region portion 22 has a rectangular shape when viewed in projection, and the inner portion 22a constitutes a free end. There is one connecting portion 22b that connects the inner portion 22a and the main portion 21.

[0112] The opening portion 23 has a substantially U-shaped shape when viewed in projection with the region portion 22 sandwiched therebetween, and has a U-shaped shape when viewed in projection with one side close to the edge end of the insulating layer 20 being open. In the present embodiment, the region portion 22 and the opening portion 23 together constitute a substantially rectangular shape when viewed in projection.

[0113] The wiring portion 31 of the wiring circuit board X2 passes from one end disposed on the inner portion 22a through the connecting portion 22b and extends from the open side of the U-shaped opening portion 23 to the outside of the region portion 22.

[0114] In the insulating layer 40 of the wiring circuit board X2, similar to the opening portion 23, the opening portion 41 has a U-shaped shape when viewed in projection with one side close to the edge end of the insulating layer 20 being open.

[0115] In the insulating layer 50 of the wiring circuit board X2, the region portion 52 and the opening portion 53 are located at the above-mentioned predetermined end portion corresponding to the formation position of the via portion 12.

[0116] As Figure 20 shown, the region portion 52 has a rectangular shape when viewed in projection, and the inner portion 52a constitutes a free end. There is one connecting portion 52b that connects the inner portion 52a and the main portion 51. The connecting portion 52b is located on the opposite side of the via portion 12 in the in-plane direction orthogonal to the thickness direction with respect to the connecting portion 22b.

[0117] The opening portion 53 is a notch opening portion formed by cutting a notch from a predetermined edge end of the insulating layer 50. The opening portion 53 has a substantially U-shaped shape when viewed in projection with the region portion 52 sandwiched therebetween, and has a U-shaped shape when viewed in projection with the side opposite to the side close to the edge end of the insulating layer 50 being open.

[0118] The wiring portion 61 of the wiring circuit board X2 extends from one end disposed on the inner portion 52a through the connecting portion 52b and extends outside the region portion 52 from the open side of the U-shaped letter of the opening portion 53 (the side opposite to the open side of the U-shaped letter of the opening portion 23).

[0119] Further, when viewed in projection along the thickness direction of the wiring circuit board X2, the opening portion 23 and the opening portion 53 are connected to form a rectangular frame shape and surround the passage portion 12. In the present embodiment, the opening portions 23 and 53 are provided in such an opening shape.

[0120] Figures 23 to 26 Shows a manufacturing method of the wiring circuit board X2. Figure 23 and Figure 24 corresponding to Figure 18 changes in the cross-section to represent this manufacturing method, Figure 25 and Figure 26 corresponding to Figure 21 changes in the cross-section to represent this manufacturing method. The specific implementation methods of the following respective processes are the same as those described for the corresponding processes in the manufacturing method of the wiring circuit board X1.

[0121] In this manufacturing method, first, as Figure 23 A and Figure 25 A show, a metal core layer 10 is prepared (preparation process).

[0122] Next, as Figure 23 B and Figure 25 B show, an insulating layer 20 as a base insulating layer is formed on the metal core layer 10 (first base insulating layer formation process).

[0123] Next, as Figure 23 C and Figure 25 C show, a conductor layer 30 is formed on the insulating layer 20 (first conductor layer formation process).

[0124] Next, as Figure 23 D and Figure 25 D show, on one side in the thickness direction of the insulating layer 20, an insulating layer 40 as a covering insulating layer is formed so as to cover the conductor layer 30 (first covering insulating layer formation process).

[0125] Next, as Figure 24 A and Figure 26 A show, an insulating layer 50 as a base insulating layer is formed on the metal core layer 10 (second base insulating layer formation process).

[0126] Next, as Figure 24 B and Figure 26 B show, a conductor layer 60 is formed on the insulating layer 50 (second conductor layer formation process).

[0127] Next, as shown in Figure 24 C and Figure 26 C, on the other side in the thickness direction of the insulating layer 50, an insulating layer 70 (second covering insulating layer forming step) is formed so as to cover the conductor layer 60.

[0128] In the present embodiment, through the above-described respective steps, a laminate Y3 can be obtained as an intermediate product.

[0129] In the present manufacturing method, next, as shown in Figure 24 D and Figure 26 D, by performing an etching process on the metal core layer 10, a core layer main part 11 and a via part 12 are formed in the metal core layer 10 (etching step).

[0130] In addition, in the present embodiment, since the opening 53 is formed as a notch opening, the etching process for shaping the outer shape of the metal core layer 10 is also performed by the first etching process and the second etching process. Thereby, the formation of the via part 12 of the metal core layer 10 and the shaping of the outer shape of the metal core layer 10 can be carried out in parallel.

[0131] As described above, a wiring circuit board X2 having a via part 12 formed at an end of the metal core layer 10 can be manufactured.

[0132] In the wiring circuit board X2 and its manufacturing method, the same operational effects as those described above for the wiring circuit board X1 and its manufacturing method can be achieved.

[0133] In the manufacturing method of the wiring circuit board X2, alternatively, a laminate Y4 provided with resist masks 101 and 102 instead of the insulating layers 40 and 70 may be used, Figure 27 as shown, to perform the etching process on the metal core layer 10. Specifically, it is the same as the description of the case of using the laminate Y2 and performing the etching process with respect to the wiring circuit board X1 above.

[0134] In addition, regarding the present invention, the above-described respective embodiments and respective modification examples can be appropriately combined and implemented.

[0135] Industrial Applicability

[0136] Technologies related to the double-sided wiring circuit board of the present invention can be applied to various flexible wiring boards, for example.

[0137] Description of Reference Numerals

[0138] X1, X2, a wiring circuit board (a double-sided wiring circuit board); Y1, Y2, Y3, Y4, a laminate; 10, a metal core layer; 11, a main body portion of the core layer; 12, a via portion; 13, a void; 20, 40, 50, 70, an insulating layer; 21, 51, a main body portion; 22, 52, a region portion; 22c, 52c, a hole portion; 23, 41, 53, 71, an opening portion; 30, 60, a conductor layer; 31, 61, a wiring portion; 32, 62, a conduction portion.

Claims

1. A manufacturing method of a double-sided wiring circuit board, characterized in that, The manufacturing method of the double-sided wiring circuit board includes: The first process, in which a laminate is prepared. The laminate includes a metal core layer, a first insulating layer, a first conductor layer, a second insulating layer, and a second conductor layer. The first insulating layer is disposed on one side in the thickness direction of the metal core layer, and includes a first region portion having a first hole portion and at least one first opening portion adjacent to the first region portion. The first conductor layer has a first wiring portion and a first conduction portion. The first wiring portion is disposed at least on the first region portion on one side in the thickness direction of the first insulating layer, and the first conduction portion is disposed in the first hole portion and is connected to the first wiring portion and the metal core layer. The second insulating layer is disposed on the other side in the thickness direction of the metal core layer and has a second region portion and at least one second opening portion adjacent to the second region portion. The second region portion includes a portion opposite to the first region portion in the thickness direction and has a second hole portion in this portion. The second conductor layer has a second wiring portion and a second conduction portion. The second wiring portion is disposed at least on the second region portion on the other side in the thickness direction of the second insulating layer, and the second conduction portion is disposed in the second hole portion and is connected to the second wiring portion and the metal core layer; and The second process, in which a first etching process of the metal core layer is performed from one side in the thickness direction of the laminate through the first opening portion, and a second etching process of the metal core layer is performed from the other side in the thickness direction of the laminate through the second opening portion, so as to form a via portion in the metal core layer. The periphery of the via portion is surrounded by a void, and the via portion extends in the thickness direction between the first region portion and the second region portion and is connected to the first conduction portion and the second conduction portion.

2. The manufacturing method of the double-sided wiring circuit board according to claim 1, characterized in that, The first etching process and the second etching process are performed simultaneously.

3. The manufacturing method of the double-sided wiring circuit board according to claim 1, characterized in that, When observed in projection along the thickness direction, the first opening portion and the second opening portion surround the first conduction portion and the second conduction portion in a connected manner.

4. The manufacturing method of the double-sided wiring circuit board according to claim 1, characterized in that, The laminate further includes: A third insulating layer, which covers the first conductor layer on one side in the thickness direction of the first insulating layer and has a third opening portion communicating with the first opening portion; and A fourth insulating layer, which covers the second conductor layer on the other side in the thickness direction of the second insulating layer and has a fourth opening portion communicating with the second opening portion.

5. A double-sided wiring circuit board, characterized in that, The double-sided wiring circuit board includes: A metal core layer, which includes a via portion surrounded by a void and a core layer main portion adjacent to the via portion across the void; The first insulating layer is disposed on one side in the thickness direction of the metal core layer, and includes a first region portion having a first hole portion and at least one first opening portion adjacent to the first region portion: The first conductor layer has a first wiring portion and a first conduction portion. The first wiring portion is disposed at least on the first region portion on one side in the thickness direction of the first insulating layer, and the first conduction portion is disposed in the first hole portion and connected to the first wiring portion and the metal core layer; The second insulating layer is disposed on the other side in the thickness direction of the metal core layer and has a second region portion and at least one second opening portion adjacent to the second region portion. The second region portion includes a portion opposite to the first region portion in the thickness direction and has a second hole portion in this portion; and The second conductor layer has a second wiring portion and a second conduction portion. The second wiring portion is disposed at least on the second region portion on the other side in the thickness direction of the second insulating layer, and the second conduction portion is disposed in the second hole portion and connected to the second wiring portion and the metal core layer.

6. The two-sided wiring circuit board according to claim 5, wherein when viewed in projection along the thickness direction, the first opening portion and the second opening portion are connected to surround the first conduction portion and the second conduction portion.

Images