Wiring circuit board and method for manufacturing the same

Abstract

To provide a wiring circuit board suitable to achieve electric connection with low resistance between a metal support substrate and a wiring layer formed on an insulating layer on the substrate, and a manufacturing method for the wiring circuit board.SOLUTION: A wiring circuit board X in the present invention includes a metal support substrate 10, a metal thin film 20, an insulating layer 30, a metal thin film 40, and a conductive layer 50 in order in a thickness direction D. The insulating layer 30 has a penetration hole 31 penetrating in the thickness direction D. A penetration hole 30A includes an opening end 31 on the metal thin film 10 side, an opening end 32 on the opposite side of the opening end 31, and an inner wall surface 33 between the opening ends 31 and 32. The metal thin film 20 includes an opening part 20A. The opening part 20A overlaps with the opening end 31 in a projection view in the thickness direction D. The metal thin film 40 includes an opening part 40A. The opening part 40A overlaps with the opening part 20A and the opening end 32 in the projection view in the thickness direction D. The conductive layer 50 includes a veer part 52 disposed in the penetration hole 30A and connected to the metal support substrate 10.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wiring circuit board and a method for manufacturing the same.

Background Art

[0002] A wiring circuit board including a metal support substrate, an insulating layer on the metal support substrate, and a wiring pattern (wiring layer) on the insulating layer is known. In such a wiring circuit board, for example, a metal thin film for ensuring the adhesion of the insulating layer to the metal support substrate is provided between the metal support substrate and the insulating layer. Technologies related to such wiring circuit boards are described, for example, in Patent Document 1 below.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The wiring circuit board has, for example, vias that penetrate the insulating layer in the thickness direction to electrically connect the metal support substrate and the wiring pattern. Such a wiring circuit board has conventionally been manufactured, for example, as follows.

[0005] First, a thin metal film (first thin metal film) is formed on a metal support substrate. Next, an insulating layer having via holes is formed on the first thin metal film (insulating layer formation process). This insulating layer formation process includes a heating process. Next, a seed layer is formed on the insulating layer. The seed layer is also formed in the via holes. In the via holes, the seed layer is formed so as to cover the exposed surface of the first thin metal film and the inner wall surface of the via hole. The seed layer is a thin metal film (second thin metal film). Next, a conductor layer is formed on the seed layer. The conductor layer includes a first conductor portion having a predetermined pattern on the insulating layer and a second conductor portion in the via hole. Next, any portion of the seed layer not covered by the conductor layer is removed. As a result, a wiring pattern consisting of the seed layer and the first conductor portion on it is formed on the insulating layer, and vias consisting of the seed layer and the second conductor portion on it are formed on the first thin metal film in the via hole.

[0006] In such conventional manufacturing methods, the surface of the first metal thin film exposed in the via holes is oxidized during the insulating layer formation process (which includes a heating process). As a result, vias are formed in the via holes on the first metal thin film having an oxide film on its surface. Therefore, in the manufactured wiring circuit board, the vias are electrically connected to the metal support substrate via the first metal thin film having an oxide film. Furthermore, if the seed layer is made of a relatively high-resistance material, the vias are electrically connected to the metal support substrate via such a seed layer. These configurations are undesirable from the viewpoint of reducing the resistance of the electrical connection between the metal support substrate and the wiring layer.

[0007] The present invention provides a wiring circuit board suitable for achieving low-resistance electrical connections between a metal support substrate and a wiring layer formed on an insulating layer on the substrate, and a method for manufacturing the same. [Means for solving the problem]

[0008] The present invention [1] includes a wiring circuit board comprising, in order in the thickness direction, a metal support substrate, a first metal thin film, an insulating layer, a second metal thin film, and a conductor layer, wherein the insulating layer has a through hole penetrating in the thickness direction, the through hole having a first open end on the side of the first metal thin film, a second open end on the opposite side of the first open end, and an inner wall surface between the first and second open ends, the first metal thin film has a first opening, the first opening overlapping with the first open end in a projection view in the thickness direction, the second metal thin film has a second opening, the second opening overlapping with the first opening and the second open end in a projection view in the thickness direction, and the conductor layer has via portions disposed in the through hole and connected to the metal support substrate.

[0009] The present invention [2] includes the wiring circuit board described in [1] above, wherein the metal support substrate comprises a metal support layer and a surface metal layer disposed on the insulating layer side of the metal support layer and having a higher conductivity than the metal support layer, and the via portion is connected to the surface metal layer.

[0010] The present invention [3] includes the wiring circuit board described in [1] or [2] above, wherein the first opening is open along the first opening end.

[0011] The present invention [4] includes a wiring circuit board according to any one of [1] to [3] above, wherein the second metal thin film has a first coating portion on the inner wall surface.

[0012] The present invention [5] includes the wiring circuit board described in [4] above, wherein the second opening is open on the metal support substrate along the first opening.

[0013] The present invention [6] includes the wiring circuit board described in [4] above, wherein the second metal thin film has a second coating portion on the metal support substrate, and the second opening is located inside the first opening on the metal support substrate.

[0014] The present invention [7] includes a wiring circuit board according to any one of [1] to [3] above, wherein the second opening is open on the insulating layer along the second opening end.

[0015] The present invention [8] includes a wiring circuit board according to any one of [1] to [3] above, wherein the second opening is opened on the insulating layer and the second opening end is located within the second opening in a projection view in the thickness direction.

[0016] The present invention [9] includes a wiring circuit board according to [1] or [2] above, wherein the first metal thin film has an extension that extends inward in the first opening end in a projection view in the thickness direction and defines the first opening, and the second metal thin film has a first covering portion on the inner wall surface and a second covering portion on the extension portion, and the second opening opens along the first opening.

[0017] The present invention

[10] includes a method for manufacturing a wiring circuit board, comprising: a first metal thin film forming step of forming a first metal thin film on one surface in the thickness direction of a metal support substrate; an insulating layer forming step of forming an insulating layer on one surface in the thickness direction of the first metal thin film, having a through hole with a first open end on the side of the first metal thin film, a second open end on the opposite side of the first open end, and an inner wall surface between the first and second open ends; a second metal thin film forming step of forming a second metal thin film over one surface in the thickness direction of the insulating layer and over the first metal thin film in the through hole; an opening forming step of forming openings in the first metal thin film and the second metal thin film that overlap with the first open end and the second open end in a projection view in the thickness direction, thereby exposing the metal support substrate in the through hole; and a conductor layer forming step of forming a conductor layer over one surface in the thickness direction of the second metal thin film and over the metal support substrate in the through hole.

[0018] The present invention

[11] comprises a first metal thin film forming step of forming a first metal thin film on one surface in the thickness direction of a metal support substrate; an insulating layer forming step of forming an insulating layer on one surface in the thickness direction of the first metal thin film, having a through hole having a first open end on the side of the first metal thin film, a second open end on the opposite side of the first open end, and an inner wall surface between the first and second open ends; a first opening forming step of forming a first opening in the first metal thin film that opens along the first open end, exposing the metal support substrate through the through hole; and the insulating layer The method for manufacturing a wiring circuit board includes: a second metal thin film forming step of forming a second metal thin film on one surface in the thickness direction and on the metal support substrate in the through hole; a second opening forming step of forming a second opening in the second metal thin film that overlaps with the first opening and the second opening end in the projection view in the thickness direction, thereby exposing the metal support substrate in the through hole; and a conductor layer forming step of forming a conductor layer on one surface in the thickness direction of the second metal thin film and on the metal support substrate in the through hole. [Effects of the Invention]

[0019] In the wiring circuit board of the present invention, in a projection view in the thickness direction, the first opening of the first metal thin film overlaps with the first opening end of the through hole in the insulating layer, and the second opening of the second metal thin film overlaps with the first opening and the second opening end of the through hole. The wiring circuit board is suitable for securing air gaps that communicate in the thickness direction across the first opening, the through hole, and the second opening as air gaps for via formation during the manufacturing process. Furthermore, in the wiring circuit board, as described above, the via portion of the conductor layer is directly connected to the metal support substrate without interposing the first metal thin film or the second metal thin film. Such a wiring circuit board is suitable for achieving low-resistance electrical connections between the metal support substrate and the wiring layer formed on the insulating layer on the substrate.

[0020] The method for manufacturing a wiring circuit board according to the present invention is suitable for manufacturing such a wiring circuit board. [Brief explanation of the drawing]

[0021] [Figure 1] It is a partial cross-sectional view of an embodiment of the wiring circuit board of the present invention. [Figure 2] It is a partially enlarged cross-sectional view of a part of the wiring circuit board shown in FIG. 1. [Figure 3] It shows a part of the steps in an embodiment of the manufacturing method of the wiring circuit board of the present invention. FIG. 3A shows the preparation step, FIG. 3B shows the first metal thin film formation step, FIG. 3C shows the base insulation layer formation step, and FIG. 3D shows the second metal thin film formation step. [Figure 4] It shows the steps following the step shown in FIG. 3D. FIG. 4A shows the opening formation step, FIG. 4B shows the conductor layer formation step, FIG. 4C shows the etching step, and FIG. 4D shows the cover insulation layer formation step. [Figure 5] It shows a modification example of the conductor layer formation and etching steps. [Figure 6] It is a partially enlarged cross-sectional view of a first modification example of the wiring circuit board shown in FIG. 1. [Figure 7] It is a partially enlarged cross-sectional view of a second modification example of the wiring circuit board shown in FIG. 1. [Figure 8] It is a partially enlarged cross-sectional view of a third modification example of the wiring circuit board shown in FIG. 1. [Figure 9] It is a partially enlarged cross-sectional view of a fourth modification example of the wiring circuit board shown in FIG. 1. [Figure 10] It is a partially enlarged cross-sectional view of a fifth modification example of the wiring circuit board shown in FIG. 1. [Figure 11] It is a partially enlarged cross-sectional view of a sixth modification example of the wiring circuit board shown in FIG. 1. [Figure 12] It is a partially enlarged cross-sectional view of a seventh modification example of the wiring circuit board shown in FIG. 1. [Figure 13] It is a partially enlarged cross-sectional view of an eighth modification example of the wiring circuit board shown in FIG. 1. [Figure 14] It is a partially enlarged cross-sectional view of a ninth modification example of the wiring circuit board shown in FIG. 1. [Figure 15] It is a partially enlarged cross-sectional view of a tenth modification example of the wiring circuit board shown in FIG. 1. [Figure 16] It is a partially enlarged cross-sectional view of an eleventh modification example of the wiring circuit board shown in FIG. 1. [Figure 17]This is a partially enlarged cross-sectional view of the 12th modified example of the wiring circuit board shown in Figure 1. [Figure 18] Figure 18A shows some steps in another embodiment of the manufacturing method for a wiring circuit board of the present invention. Figure 18A shows the preparation step, Figure 18B shows the first metal thin film formation step, and Figure 18C shows the base insulating layer formation step. [Figure 19] Figure 19A represents the process that follows the process shown in Figure 18C. Figure 19A represents the first aperture formation process, Figure 19B represents the second metal thin film formation process, and Figure 19C represents the second aperture process. [Figure 20] Figure 19C shows the process that follows. Figure 20A shows the conductor layer formation process, Figure 20B shows the etching process, and Figure 20C shows the cover insulation layer formation process. [Figure 21] This is a partially enlarged cross-sectional view of the 13th modified example of the wiring circuit board shown in Figure 1. [Figure 22] This is a partially enlarged cross-sectional view of the 14th modified example of the wiring circuit board shown in Figure 1. [Figure 23] This is a partially enlarged cross-sectional view of the 15th modified example of the wiring circuit board shown in Figure 1. [Modes for carrying out the invention]

[0022] As one embodiment of the wiring circuit board of the present invention, the wiring circuit board X, as shown in Figures 1 and 2, comprises a metal support substrate 10, a metal thin film 20, an insulating layer 30 as a base insulating layer, a metal thin film 40, a conductor layer 50, and an insulating layer 60 as a cover insulating layer, arranged in order toward one side in the thickness direction D. The wiring circuit board X extends in a direction perpendicular to the thickness direction D (plane direction) and has a predetermined planar shape.

[0023] The metal support substrate 10 is a base material for ensuring the strength of the wiring circuit board X. Examples of materials for the metal support substrate 10 include stainless steel, copper, copper alloy, aluminum, nickel, titanium, and 42 alloy. Examples of stainless steel include SUS304 based on the AISI (American Iron and Steel Institute) standard. From the viewpoint of strength of the metal support substrate 10, the metal support substrate 10 preferably includes at least one selected from the group consisting of stainless steel, copper alloy, aluminum, nickel, and titanium, and more preferably consists of at least one selected from the group consisting of stainless steel, copper alloy, aluminum, nickel, and titanium. From the viewpoint of balancing strength and conductivity of the metal support substrate 10, the metal support substrate 10 is preferably made of a copper alloy. The thickness of the metal support substrate 10 is, for example, 15 μm or more. The thickness of the metal support substrate 10 is, for example, 500 μm or less, preferably 250 μm or less.

[0024] The metal thin film 20 is arranged on one surface of the metal support substrate 10 in the thickness direction D. The metal thin film 20 is in contact with the metal support substrate 10. The metal thin film 20 is a film that ensures the adhesion of the insulating layer 30 to the metal support substrate 10. Examples of the metal thin film 20 include a film deposited by sputtering (sputtered film), a film deposited by plating (plated film), and a film deposited by vacuum deposition (vacuum deposited film).

[0025] Examples of materials for the metal thin film 20 include chromium, nickel, and titanium. The material for the metal thin film 20 may also be an alloy containing two or more metals selected from the group consisting of chromium, nickel, and titanium. Chromium is preferably used as the material for the metal thin film 20.

[0026] The thickness of the metal thin film 20 is, for example, 1 nm or more, preferably 10 nm or more, and more preferably 20 nm or more. The thickness of the metal thin film 20 is, for example, 1000 nm or less, preferably 1000 nm or less, and more preferably 500 nm or less.

[0027] The metal thin film 20 has an opening 20A (first opening) that penetrates the metal thin film 20 in the thickness direction D. The opening 20A has, for example, a substantially circular shape in plan view. The maximum length of the opening 20A in plan view (or diameter if the opening 20A has a circular shape in plan view) is, for example, 1 μm or more and, for example, 1000 μm or less, depending on the size of the through hole 30A of the insulating layer 30 described later. The metal support substrate 10 has a portion 10a facing the opening 20A. The portion 10a is not covered by the metal thin films 20, 40.

[0028] The insulating layer 30 is arranged on one surface in the thickness direction D of the metal thin film 20. The insulating layer 30 is in contact with the metal thin film 20. Examples of materials for the insulating layer 30 include resin materials such as polyimide, polyethernitrile, polyethersulfone, polyethylene terephthalate, polyethylene naphthalate, and polyvinyl chloride (similar resin materials can also be used for the insulating layer 60 described later). The thickness of the insulating layer 30 is, for example, 1 μm or more, preferably 3 μm or more. The thickness of the insulating layer 30 is, for example, 35 μm or less.

[0029] The insulating layer 30 has a through hole 30A that penetrates the insulating layer 30 in the thickness direction D. The through hole 30A has an open end 31 (first open end) on the metal thin film 20 side, an open end 32 (second open end) on the opposite side of the open end 31, and an inner wall surface 33 between the open ends 31 and 32.

[0030] The open end 31 has, for example, a substantially circular shape in plan view. The maximum length of the open end 31 (or diameter if the open end 31 has a circular shape) is, for example, 1 μm or more, and also, for example, 1000 μm or less. In a projection view in the thickness direction D, the open end 31 and the opening 20A of the metal thin film 20 overlap (the positional relationship between the open end 31 and the opening 20A in a projection view in the thickness direction D is schematically shown below the cross-sectional view in Figure 2). That is, the opening 20A overlaps with the open end 31 in a projection view in the thickness direction D. In this embodiment, the open end 31 opens along the opening 20A. That is, the opening 20A opens along the open end 31. Also, in a projection view in the thickness direction D, the open end 31 includes the opening 20A.

[0031] The maximum length of the open end 32 (or diameter if the open end 32 is circular) is, for example, 1 μm or more, and also, for example, 1000 μm or less. In this embodiment, the open end 32 has a larger area than the open end 31. In a projection view in the thickness direction D, the open end 32 includes the open end 31.

[0032] In this embodiment, the inner wall surface 33 is inclined. The inner wall surface 33 is inclined such that the portion closer to the metal support substrate 10 is positioned inward. That is, the inner wall surface 33 is inclined such that the opening cross-sectional area of ​​the through hole 30A becomes smaller in the portion closer to the metal support substrate 10.

[0033] The through-hole 30A and the opening 20A in the thin metal film 20 form a through-hole H.

[0034] In this embodiment, the metal thin film 40 is directly arranged on one surface in the thickness direction D of the insulating layer 30 and on the inner wall surface 33 of the through hole 30A. The metal thin film 40 is a seed layer for forming the conductive layer 50. Examples of the metal thin film 40 include sputtered films, plated films, and vacuum-deposited films.

[0035] The metal thin film 40 includes a metal thin film 41 located outside the through hole H and a metal thin film 42 located inside the through hole H. The metal thin film 41 and the metal thin film 42 are connected. The metal thin film 41 has a predetermined pattern shape on the insulating layer 30. The metal thin film 42 covers the entire inner wall surface 33. That is, in this embodiment, the metal thin film 42 is a covering portion 42a (first covering portion) on the inner wall surface 33. Having a covering portion 42a in the metal thin film 42 helps in growing metal on the covering portion 42a to properly form via portions 52 in the conductor layer formation process (shown in Figure 4B) described later. Furthermore, the metal thin film 42 is connected to the metal thin film 20 inside the through hole H.

[0036] The metal thin film 40 has an opening 40A (second opening) that penetrates the metal thin film 40 in the thickness direction D. In this embodiment, the opening 40A is located within the through hole H. In plan view, the opening 40A has, for example, a substantially circular shape. The maximum length of the opening 40A in plan view (the diameter if the opening 20A has a circular shape in plan view) is, for example, 1 μm or more, and also, for example, 1000 μm or less, depending on the size of the through hole 30A.

[0037] In a projection view in the thickness direction D, the opening 40A overlaps with the opening 20A of the metal thin film 20 and the opening end 32 of the through hole 30A (the positional relationship between the openings 20A, 40A and the opening end 32 in a projection view in the thickness direction D is schematically shown below the cross-sectional view in Figure 2). In this embodiment, the opening 40A is open on the metal support substrate 10 along the opening 20A.

[0038] Examples of materials for the metal thin film 40 include chromium, copper, nickel, and titanium. The material for the metal thin film 40 may also be an alloy containing two or more metals selected from the group consisting of chromium, copper, nickel, and titanium. Chromium is preferably used as the material for the metal thin film 40. The metal thin film 40 may have a single-layer structure or a multilayer structure of two or more layers. If the metal thin film 40 has a single-layer structure, it is preferably a chromium layer. If the metal thin film 40 has a multilayer structure, it preferably consists of a chromium layer as a lower layer and a copper layer on the chromium layer.

[0039] The thickness of the metal thin film 40 is, for example, 1 nm or more, preferably 10 nm or more. The thickness of the metal thin film 40 is, for example, 500 nm or less, preferably 200 nm or less.

[0040] The conductor layer 50 is directly arranged on one surface of the metal thin film 40 in the thickness direction D and on a portion 10a (part of the metal support substrate 10) within the through hole H. The conductor layer 50 includes a wiring portion 51 located outside the through hole H and a via portion 52 located inside the through hole H. The wiring portion 51 has a predetermined pattern shape. A portion of the wiring portion 51 and the via portion 52 are connected. The via portion 52 has a concave shape in the longitudinal cross-section shown in Figure 2. The via portion 52 has an inclined circumferential surface 52a. The circumferential surface 52a is inclined so that the portion closer to the metal support substrate 10 is positioned inward. That is, the circumferential surface 52a is inclined so that the cross-sectional area of ​​the via portion 52 becomes smaller in the portion closer to the metal support substrate 10. The via portion 52 is also connected to the metal support substrate 10. Specifically, the via portion 52 is directly connected to the metal support substrate 10 without the metal thin films 20 and 40.

[0041] Examples of materials for the conductive layer 50 include copper, nickel, and gold. The conductive layer 50 may also be an alloy containing two or more metals selected from the group consisting of copper, nickel, and gold. Copper is preferably used as the material for the conductive layer 50.

[0042] On the insulating layer 30, the metal thin film 41 and the wiring portion 51 on the metal thin film 41 form a wiring layer 71 having a predetermined pattern shape. In the through hole H, the metal thin film 42 and the via portion 52 form vias 72. The metal support substrate 10 and a part of the wiring layer 71 are electrically connected via the vias 72. The wiring layer 71 can be connected to ground via the vias 72 and the metal support substrate 10.

[0043] The thickness of the wiring layer 71 is, for example, 3 μm or more, preferably 5 μm or more. The thickness of the wiring layer 71 is, for example, 50 μm or less, preferably 30 μm or less. The width of the wiring layer 71 (the dimension in the direction perpendicular to the elongation direction of the wiring layer 71) is, for example, 5 μm or more, preferably 8 μm or more. The width of the wiring layer 71 is, for example, 100 μm or less, preferably 50 μm or less.

[0044] The insulating layer 60 is directly arranged on one side of the insulating layer 30 in the thickness direction D, covering the wiring layer 71 and vias 72. The thickness of the insulating layer 60 is, for example, 4 μm or more, preferably 6 μm or more. The thickness of the insulating layer 60 (height from the insulating layer 30) is, for example, 60 μm or less, preferably 40 μm or less. The insulating layer 60 may have openings that partially expose the wiring layer 71 and / or vias 72. That is, the insulating layer 60 may have openings through which the wiring layer 71 and / or vias 72 are exposed. The portions of the wiring layer 71 and / or vias 72 exposed through these openings can function, for example, as terminal portions of the wiring circuit board X.

[0045] In the wiring circuit board X, as described above, in a projection view in the thickness direction D, the opening 20A of the metal thin film 20 overlaps with the opening end 31 of the through hole 30A of the insulating layer 30, and the opening 40A of the metal thin film 40 overlaps with the opening 20A and the opening end 32 of the through hole 30A. In this embodiment, in a projection view in the thickness direction D, the opening 20A and the opening 40A substantially coincide. In the schematic projection diagram in Figure 2, cross-hatching is applied to the region R where all of the openings 20A, 40A and the opening ends 31, 32 overlap.

[0046] Such a wiring circuit board X is suitable for securing voids in the thickness direction D across the openings 20A, through holes 30A, and 40A during the manufacturing process as voids for via formation (region R is continuous in the thickness direction D across the openings 20A, through holes 30A, and 40A). Furthermore, in the wiring circuit board X, as described above, the via portion 52 of the conductor layer 50 is directly connected to the metal support substrate 10 without the metal thin films 20 and 40. Such a wiring circuit board X is suitable for achieving low-resistance electrical connections between the metal support substrate 10 and the wiring layer 71 on the insulating layer 30.

[0047] In the wiring circuit board X, as described above, the metal thin film 40 includes a metal thin film 42 within the through-hole 30A of the insulating layer 30, the metal thin film 42 is connected to the metal thin film 20 on the metal support substrate 10, and the opening 40A opens along the opening 20A of the metal thin film 20. This configuration is useful in the conductor layer formation process (shown in Figure 4B) described later for growing metal on the covering portion 42a to properly form the via portion 52.

[0048] Figures 3A to 3D and 4A to 4D illustrate a method for manufacturing a wiring circuit board X as one embodiment of the present invention. Figures 3A to 3D and 4A to 4D represent this manufacturing method as a change in the cross-section corresponding to Figure 1.

[0049] In this manufacturing method, first, a metal support substrate 10 is prepared as shown in Figure 3A (preparation step).

[0050] Next, as shown in Figure 3B, a thin metal film 20 is formed on one surface of the metal support substrate 10 in the thickness direction D (first thin metal film formation step). Examples of methods for forming the thin metal film 20 include sputtering, vacuum deposition, and plating. Examples of plating methods include electrolytic plating and electroless plating. The thin metal film 20 is preferably formed by sputtering.

[0051] Next, as shown in Figure 3C, an insulating layer 30 is formed on one surface in the thickness direction D of the metal thin film 20 (base insulating layer formation step). In this step, the insulating layer 30 is formed, for example, as follows: First, a photosensitive resin solution (varnish) is applied to the metal thin film 20 to form a coating film. Next, this coating film is dried by heating. Next, the coating film is subjected to exposure treatment through a predetermined mask, followed by development treatment, and then baking treatment as necessary. For example, an insulating layer 30 having through holes 30A can be formed on the metal thin film 20 in this manner. A portion 20a of the metal thin film 20 is exposed in the through holes 30A. The exposed surface of portion 20a (upper surface in the figure) is oxidized through the heating process included in this step.

[0052] Next, as shown in Figure 3D, a thin metal film 40 is formed as a seed layer (second thin metal film formation step). In this step, the thin metal film 40 is formed continuously on one surface of the insulating layer 30 in the thickness direction D, on the inner wall surface 33 of the through hole 30A, and on the portion 20a of the thin metal film 20 exposed in the through hole 30A (the thin metal film 40 includes the thin metal film 41 outside the through hole 30A and the thin metal film 42 inside the through hole 30A). Examples of methods for forming the thin metal film 40 include sputtering, vacuum deposition, and plating. Examples of plating methods include electrolytic plating and electroless plating. The thin metal film 40 is preferably formed by sputtering.

[0053] Next, as shown in Figure 4A, openings 20A and 40A are formed in the metal thin films 20 and 40 (opening formation step). Specifically, for example, it is as follows.

[0054] First, an etching mask M is formed on the metal thin film 40. The etching mask M has etching openings Ma. The etching openings Ma have a planar shape corresponding to the planar shape of the opening 40A. In forming the etching mask M, first, a photosensitive resist film is bonded to the metal thin film 40 to form a resist film. Next, the resist film is subjected to exposure treatment through a predetermined mask, followed by development treatment, and then baking treatment as necessary. In this way, etching openings Ma corresponding to the openings 20A and 40A to be formed in the metal thin films 20 and 40 are formed.

[0055] In this step, the metal thin films 20 and 40 are etched via an etching mask M on the metal thin film 40. This removes the portion of the metal thin film 40 facing the etching opening Ma, and then the portion of the metal thin film 20 facing the etching opening Ma. This forms the openings 20A and 40A. After this, the etching mask M is removed from the metal thin film 40. Etching methods include wet etching and dry etching, with wet etching being preferred. Etching solutions used in wet etching include, for example, ceric ammonium nitrate solution, aqueous solution of caustic soda, potassium permanganate solution, and sodium metasilicate solution, with ceric ammonium nitrate solution being preferred. The temperature of the etching solution in wet etching is, for example, 20°C or higher, preferably 30°C or higher. The etching solution temperature is, for example, 80°C or lower, preferably 65°C or lower. The etching time in wet etching is, for example, 1 minute or more. The etching time is, for example, 15 minutes or less, preferably 10 minutes or less.

[0056] In this process, openings 20A and 40A can be formed in the metal thin films 20 and 40 as described above. The openings 20A and 40A overlap with the opening ends 31 and 32 of the through hole 30A in a projection view in the thickness direction D. Therefore, in this process, the metal support substrate 10 is exposed at the through hole 30A.

[0057] Next, as shown in Figure 4B, a conductive layer 50 is formed on one surface of the metal thin film 40 in the thickness direction D and on the metal support substrate 10 in the through hole 30A (conductive layer formation step). Specifically, for example, it is as follows.

[0058] First, a resist pattern is formed on the metal thin film 40. The resist pattern has openings in a planar shape corresponding to the pattern shape of the conductive layer 50. In forming the resist pattern, first, a photosensitive resist film is bonded to the metal thin film 40 to form a resist film. Next, the resist film is subjected to exposure treatment through a predetermined mask, followed by development treatment, and then baking treatment as necessary. In forming the conductive layer 50, the above-mentioned metal is grown on the metal thin film 40 within the openings of the resist pattern by electroplating. In the electroplating method, the metal thin film 20 and the metal support substrate 10 are used in combination as a power supply member for electroplating. Next, the resist pattern is removed. For example, in this manner, a conductive layer 50 (including wiring portions 51 and via portions 52) with a predetermined pattern can be formed on one surface in the thickness direction D of the metal thin film 40.

[0059] In this manufacturing method, as shown in Figure 4C, the portion of the metal thin film 40 not covered by the conductor layer 50 is removed by etching (etching step). This forms the wiring layer 71 (wiring portion 51, metal thin film 41) and via 72 (via portion 52, metal thin film 42). After this step, a nickel coating may be formed on the surface of the wiring layer 71 by, for example, electroless plating or electrolytic plating.

[0060] Next, as shown in Figure 4D, an insulating layer 60 is formed on the insulating layer 30 so as to cover the wiring layer 71 and vias 72 (cover insulating layer formation step). In this step, the insulating layer 60 is formed, for example, as follows: First, a photosensitive resin solution (varnish) is applied to the insulating layer 30, the wiring layer 71 and vias 72 to form a coating film. Next, this coating film is dried. Next, the coating film is subjected to exposure treatment through a predetermined mask, followed by development treatment, and then baking treatment as necessary. For example, the insulating layer 60 as a cover insulating layer can be formed in this manner.

[0061] In this manner, the wiring circuit board X can be manufactured.

[0062] In the base insulating layer formation step of this manufacturing method (shown in Figure 3C), the surface of portion 20a of the metal thin film 20 facing the through hole 30A is oxidized. In the second metal thin film formation step (shown in Figure 3D), the metal thin film 40 is formed continuously as a seed layer on the insulating layer 30 and on portion 20a inside the through hole 30A. As mentioned above, chromium is preferably used as the material for the metal thin film 40, and chromium has a higher resistance than, for example, copper, and is a relatively high-resistance conductor. However, in the opening formation step (shown in Figure 4A), portions 20a and 41 of the metal thin films 20 and 40 are removed. As a result, a part (part 10a) of the metal support substrate 10 is exposed. Therefore, in the conductor layer formation step (shown in Figure 4B), via portions 52 that are directly connected to portion 10a of the metal support substrate 10 are formed.

[0063] Thus, according to this manufacturing method, via portions 52 in the wiring circuit board X can be formed to be directly connected to the metal support substrate 10 (the via portions 52 are not electrically connected to the metal support substrate 10 via the metal thin films 20 and 40). Therefore, this manufacturing method is suitable for achieving low-resistance electrical connections between the metal support substrate 10 and the wiring layer 71 in the wiring circuit board X.

[0064] In this manufacturing method, after the opening formation step (shown in Figure 4A) described above, instead of the conductor layer formation step (shown in Figure 4B) and etching step (shown in Figure 4C), the conductor layer formation step shown in Figures 5A and 5B, followed by the etching step shown in Figure 5C, may be performed.

[0065] In the conductor layer formation process, first, a conductor thin film 50a is formed as shown in Figure 5A. Examples of materials for the conductor thin film 50a include the materials described above for the conductor layer 50, with copper being preferred. Methods for forming the conductor thin film 50a include sputtering and vacuum deposition. The conductor thin film 50a is preferably formed by sputtering. The thickness of the conductor thin film 50a is, for example, 1 nm or more, preferably 10 nm or more, and also, for example, 500 nm or less, preferably 200 nm or less.

[0066] Next, as shown in Figure 5B, a conductive layer 50b is formed on one surface in the thickness direction D of the conductive thin film 50a. Specifically, as a method for forming the conductive layer 50, the conductive layer 50b can be formed by electroplating, as described above with reference to Figure 4B. In this electroplating method, a metal thin film 20 and a conductive thin film 50a are used as power supply members for electroplating, and preferably, the metal thin film 20, the conductive thin film 50a, and the metal support substrate 10 are used in combination. This combination helps to properly form the via portion 52.

[0067] In the subsequent etching process, as shown in Figure 5C, the areas in the metal thin film 40 and the conductive thin film 50a where the conductive layer 50b is not formed are removed by etching. This forms the wiring layer 71 (wiring portion 51, metal thin film 41) and the via 72 (via portion 52, metal thin film 42). The wiring portion 51 and the via portion 52 each consist of the conductive thin film 50a and the conductive layer 50b on top of it. In Figure 2, the boundary between the conductive thin film 50a and the conductive layer 50b when the conductive layer 50 is formed as described above is shown by a dashed line (the same applies to the modified examples described later).

[0068] In the wiring circuit board X, as shown in Figure 6, the metal thin film 20 may have an extension portion 22, and the metal thin film 40 may have a covering portion 42a in addition to a covering portion 42b within the through hole H. The extension portion 22 extends into the opening end 31 of the through hole 30A in a projection view in the thickness direction D, defining the opening 20A. The covering portion 42b covers such extension portion 22. The opening 40A of the metal thin film 40 is open along the opening 20A.

[0069] The positional relationship between the opening 20A of the metal thin film 20, the opening ends 31 and 32 of the through hole 30A, and the opening 40A of the metal thin film 40 in a projection view in the thickness direction D of this modified wiring circuit board X (first modified example) is schematically shown below the cross-sectional view in Figure 6. In the projection view in the thickness direction D, the opening 20A overlaps with the opening end 31, and the opening 40A overlaps with the opening 20A and the opening end 32. In this modified example, the openings 20A and 40A substantially coincide in the projection view in the thickness direction D. In the schematic projection in Figure 6, cross-hatching is applied to the region where all of the openings 20A, 40A and the opening ends 31 and 32 overlap (the same applies to the drawings of the modified examples described later).

[0070] The first modified form can be manufactured in the same manner as the manufacturing method described above, except that: In the opening formation step (shown in Figure 4A), an etching mask M is used which has an etching opening Ma within the opening end 31 that is smaller in diameter than the opening end 31 of the through hole 30A when viewed in a projection in the thickness direction D.

[0071] This first modification is also suitable for securing voids in the thickness direction D across the opening 20A, through hole 30A, and opening 40A as voids for via formation during the manufacturing process (region R is continuous in the thickness direction D across the opening 20A, through hole 30A, and opening 40A). Furthermore, the via portion 52 of the conductor layer 50 is directly connected to the metal support substrate 10 without the metal thin films 20 and 40. Therefore, this first modification of the wiring circuit board X is also suitable for achieving low-resistance electrical connections between the metal support substrate 10 and the wiring layer 71 on the insulating layer 30. In a projection view in the thickness direction D, there is an area where all of the openings 20A, 40A and the opening ends 31, 32 overlap. Therefore, it is suitable for securing a gap in the thickness direction D across opening 20A, through hole 30A, and opening 40A as a gap for via formation during the manufacturing process. Consequently, it is suitable for achieving a low-resistance electrical connection between the metal support substrate 10 and the wiring layer 71 on the insulating layer 30. These characteristics are also the same in the modified examples described later.

[0072] In the wiring circuit board X, as shown in Figure 7, the opening 40A of the metal thin film 40 may open along the opening end 32 of the through hole 30A on the insulating layer 30, and the opening 20A of the metal thin film 20 may open along the opening end 31 of the through hole 30A on the metal support substrate 10 (in this case, the metal thin film 40 does not have a metal thin film 42 within the through hole 30A).

[0073] The positional relationship between the opening 20A of the metal thin film 20, the opening ends 31 and 32 of the through hole 30A, and the opening 40A of the metal thin film 40 in a projection view in the thickness direction D of this modified example of the wiring circuit board X (second modified example) is schematically shown below the cross-sectional view in Figure 7. In the projection view in the thickness direction D, the opening 20A overlaps with the opening end 31, and the opening 40A overlaps with the opening 20A and the opening end 32. In this modified example, in the projection view in the thickness direction D, the opening 20A and the opening end 31 substantially coincide, and the opening 40A and the opening end 32 substantially coincide.

[0074] The second modified form can be manufactured in the same manner as the manufacturing method described above, except that: In the opening formation step (shown in Figure 4A), an etching mask M is used which has an etching opening Ma that substantially coincides with the opening end 32 of the through hole 30A in a projection view in the thickness direction D.

[0075] In the wiring circuit board X, as shown in Figure 8, the opening 40A of the metal thin film 40 opens on the insulating layer 30, and in a projection view in the thickness direction D, the opening end 32 is positioned within the opening 40A, and the opening 20A of the metal thin film 20 may open along the opening end 31 of the through hole 30A in the metal support substrate 10 (in this case, the metal thin film 40 does not have a metal thin film 42 within the through hole 30A).

[0076] The positional relationship between the opening 20A of the metal thin film 20, the opening ends 31 and 32 of the through hole 30A, and the opening 40A of the metal thin film 40 in a projection view in the thickness direction D of this modified example of the wiring circuit board X (third modified example) is schematically shown below the cross-sectional view in Figure 8. In the projection view in the thickness direction D, the opening 20A overlaps with the opening end 31, and the opening 40A overlaps with the opening 20A and the opening end 32. In this modified example, the opening 20A and the opening end 31 substantially coincide in the projection view in the thickness direction D.

[0077] The third modification can be manufactured in the same manner as the manufacturing method described above, except that: In the opening formation step (shown in Figure 4A), an etching mask M is used that has an etching opening Ma that is larger in diameter than the opening end 32 of the through hole 30A and includes the opening end 32 when viewed in the projection direction D of the thickness direction.

[0078] In the wiring circuit board X, as shown in Figure 9, the opening 40A of the metal thin film 40 may be formed such that, in a projection view in the thickness direction D, the opening 40A of the metal thin film 40 and the opening ends 31, 32 of the through-hole 30A of the insulating layer 30 partially overlap. In this case, the inner wall surface 33 of the through-hole 30A has a portion 33a covered by the metal thin film 40 and a portion 33b not covered by the metal thin film 40.

[0079] The positional relationship between the opening 20A of the metal thin film 20, the opening ends 31 and 32 of the through hole 30A, and the opening 40A of the metal thin film 40 in a projection view in the thickness direction D of this modified example (fourth modified example) of the wiring circuit board X is schematically shown below the cross-sectional view in Figure 9. In a projection view in the thickness direction D, the opening 20A overlaps with the opening end 31, and the opening 40A overlaps with both the opening 20A and the opening end 32.

[0080] The fourth modification can be manufactured in the same manner as the manufacturing method described above, except that: In the opening formation step (shown in Figure 4A), an etching mask M is used which has etching openings Ma that partially overlap with the opening ends 31 and 32 of the through hole 30A in a projection view in the thickness direction D.

[0081] In the wiring circuit board X, as shown in Figure 10, the opening 20A of the metal thin film 20 and the opening end 31 of the through hole 30A of the insulating layer 30 may be formed such that they partially overlap in a projection view in the thickness direction D.

[0082] The positional relationship between the opening 20A of the metal thin film 20, the opening ends 31 and 32 of the through hole 30A, and the opening 40A of the metal thin film 40 in a projection view in the thickness direction D of this modified example (5th modified example) of the wiring circuit board X is schematically shown below the cross-sectional view in Figure 10. In the projection view in the thickness direction D, the opening 20A overlaps with the opening end 31, and the opening 40A overlaps with the opening 20A and the opening end 32.

[0083] The fifth modification can be manufactured in the same manner as the manufacturing method described above, except for the following: After the first metal thin film formation step (shown in Figure 3B), an opening 20A is formed in the metal thin film 20. The position where the opening 20A is formed partially overlaps with the through hole 30A of the insulating layer 30 formed in the base insulating layer formation step (shown in Figure 3C). The method for forming the opening 20A is the same as the method described above with respect to the opening formation step (shown in Figure 4A), for example. In the opening formation step (shown in Figure 4A), an etching mask M is used which has an etching opening Ma within the opening end 31 that is smaller in diameter than the opening end 31 of the through hole 30A when viewed in the thickness direction D.

[0084] As shown in Figure 11, the wiring circuit board X may include a metal support substrate 10' instead of the metal support substrate 10. The metal support substrate 10' comprises a metal support layer 11 and a surface metal layer 12 disposed on the insulating layer 30 side of the metal support layer 11.

[0085] The metal support layer 11 is a base material for ensuring the strength of the wiring circuit board X. Examples of materials for the metal support layer 11 include the materials described above for the metal support substrate 10. From the viewpoint of the strength of the metal support layer 11, the metal support layer 11 preferably comprises at least one selected from the group consisting of stainless steel, copper alloy, aluminum, nickel, and titanium, and more preferably consists of at least one selected from the group consisting of stainless steel, copper alloy, aluminum, nickel, and titanium. From the viewpoint of achieving both strength and conductivity of the metal support layer 11, the metal support layer 11 is preferably made of a copper alloy. The thickness of the metal support layer 11 is, for example, 15 μm or more. The thickness of the metal support layer 11 is, for example, 500 μm or less, preferably 250 μm or less.

[0086] The surface metal layer 12 is arranged on one surface in the thickness direction D of the metal support layer 11. The surface metal layer 12 is in contact with the metal support layer 11. In this embodiment, the surface metal layer 12 is arranged over the entire surface on one side in the thickness direction D of the metal support layer 11. Examples of the surface metal layer 12 include sputtered films, plated films, and vacuum-deposited films. The surface metal layer 12 has higher conductivity than the metal support layer 11. From the viewpoint of the conductivity of the surface metal layer 12, the surface metal layer 12 preferably includes at least one selected from the group consisting of gold, silver, and copper, and more preferably consists of at least one selected from the group consisting of gold, silver, and copper. From the viewpoint of the film-forming properties of the surface metal layer 12 when the metal support layer 11 is made of a copper alloy, the surface metal layer 12 is preferably made of copper. The thickness of the surface metal layer 12 is preferably 0.5 μm or more, more preferably 3 μm or more.

[0087] In this modified example (sixth modified example), the via portion 52 of the conductor layer 50 is connected to the surface metal layer 12 of the metal support substrate 10.

[0088] The sixth modification can be manufactured in the same manner as the manufacturing method described above, except that a metal support substrate 10' is prepared instead of the metal support substrate 10 in the preparation step.

[0089] In the sixth modified example, as described above, the via portion 52 is connected to a surface metal layer 12 with higher conductivity than the metal support layer 11 in the metal support substrate 10. Such a configuration is preferable for achieving a low-resistance electrical connection between the metal support substrate 10 and the wiring layer 71.

[0090] Figure 12 shows the seventh modification, in which the metal support substrate 10 in the first modification is replaced with a metal support substrate 10'. Figure 13 shows the eighth modification, in which the metal support substrate 10 in the second modification is replaced with a metal support substrate 10'. Figure 14 shows the ninth modification, in which the metal support substrate 10 in the third modification is replaced with a metal support substrate 10'. Figure 15 shows the tenth modification, in which the metal support substrate 10 in the fourth modification is replaced with a metal support substrate 10'. Figure 16 shows the eleventh modification, in which the metal support substrate 10 in the fifth modification is replaced with a metal support substrate 10'.

[0091] In the wiring circuit board X, as shown in Figure 17, the metal thin film 40 is in contact with the metal support substrate 10 through a through hole H, and the opening 40A of the metal thin film 40 may be open on the metal support substrate 10 along the opening 20A of the metal thin film 20. In such a wiring circuit board X, in a projection view in the thickness direction D, the opening 20A of the metal thin film 20 overlaps with the opening end 31 of the through hole 30A of the insulating layer 30, and the opening 40A of the metal thin film 40 overlaps with the opening 20A and the opening end 32 of the through hole 30A. In this modified example (12th modified example), in a projection view in the thickness direction D, the opening 20A and the opening end 31 substantially coincide.

[0092] Figures 18A to 18C, 19A to 19C, and 20A to 20C illustrate another embodiment of the method for manufacturing a wiring circuit board according to the present invention, specifically a twelfth modified example of the wiring circuit board X (shown in Figure 17).

[0093] In this manufacturing method, first, a metal support substrate 10 is prepared as shown in Figure 18A (preparation step).

[0094] Next, as shown in Figure 18B, a thin metal film 20 is formed on one surface of the metal support substrate 10 in the thickness direction D (first thin metal film formation step). Specifically, this is the same as described above with reference to Figure 3B.

[0095] Next, as shown in Figure 18C, an insulating layer 30 is formed on one surface in the thickness direction D of the metal thin film 20 (base insulating layer formation step). Specifically, this is the same as described above with reference to Figure 3C.

[0096] Next, as shown in Figure 19A, an opening 20A is formed in the metal thin film 20 (first opening formation step). Specifically, for example, it is as follows.

[0097] First, an etching mask M' is formed on the insulating layer 30. The etching mask M' has an etching opening Mb. The etching opening Mb has a planar shape corresponding to the planar shape of the opening end 31 of the through hole 30A in the insulating layer 30. In forming the etching mask M', first, a photosensitive resist film is bonded onto the insulating layer 30 to form a resist film. Next, the resist film is subjected to exposure treatment through a predetermined mask, followed by development treatment, and then baking treatment as necessary. In this way, an etching opening Mb corresponding to the opening 20A to be formed in the metal thin film 20 is formed.

[0098] In this step, the metal thin film 20 is then etched through an etching mask M' on the insulating layer 30. This removes the portion of the metal thin film 20 facing the etching opening Mb, thereby forming the opening 20A. After this, the etching mask M' is removed from the insulating layer 30. The etching process can be wet etching or dry etching, with wet etching being preferred. The etching solution and etching conditions are the same as those in the etching process described above, with reference to Figure 4A.

[0099] In this process, an opening 20A can be formed in the metal thin film 20 as described above. In a projection view in the thickness direction D, the opening 20A overlaps with and substantially coincides with the opening end 31 of the through hole 30A. As a result of this process, the metal support substrate 10 is exposed through the through hole 30A.

[0100] Next, as shown in Figure 19B, a metal thin film 40 is formed as a seed layer (second metal thin film formation step). In this step, the metal thin film 40 is formed continuously on one surface in the thickness direction D of the insulating layer 30, on the inner wall surface 33 of the through hole 30A, and on the portion 10a of the metal support substrate 10 exposed at the through hole 30A (the metal thin film 40 includes the metal thin film 41 outside the through hole 30A and the metal thin film 42 inside the through hole 30A). The method for forming the metal thin film 40 is the same as described above with reference to Figure 3D.

[0101] Next, as shown in Figure 19C, an opening 40A is formed in the metal thin film 40 (second opening formation step). Specifically, this is the same as described above with reference to Figure 4A. This step forms an opening 40A on the metal support substrate 10 that opens along the opening 20A, and the metal support substrate 10 is exposed at the through hole 30A. The openings 20A and 40A overlap with the opening ends 31 and 32 of the through hole 30A in a projection view in the thickness direction D.

[0102] Next, as shown in Figure 20A, a conductor layer 50 (including wiring portions 51 and via portions 52) is formed on one surface of the metal thin film 40 in the thickness direction D and on the metal support substrate 10 in the through hole 30A (conductor layer formation step). Specifically, this is the same as described above with reference to Figure 4B.

[0103] Next, as shown in Figure 20B, the portion of the metal thin film 40 not covered by the conductor layer 50 is removed by etching (etching step). Specifically, this is the same as described above with reference to Figure 4C. This step forms the wiring layer 71 (wiring portion 51, metal thin film 41) and via 72 (via portion 52, metal thin film 42).

[0104] Next, as shown in Figure 20C, an insulating layer 60 is formed on the insulating layer 30 so as to cover the wiring layer 71 and vias 72 (cover insulating layer formation step). Specifically, this is the same as described above with reference to Figure 4D.

[0105] As described above, the 12th modified example of the wiring circuit board X can be manufactured.

[0106] In the base insulating layer formation step of this manufacturing method (shown in Figure 18C), the surface of portion 20a of the metal thin film 20 facing the through hole 30A is oxidized. However, in the subsequent first opening formation step (shown in Figure 19A), portion 20a of the metal thin film 20 is removed. Furthermore, in the second metal thin film formation step (shown in Figure 19B), the metal thin film 40 is formed continuously as a seed layer on the insulating layer 30 and on portion 10a of the metal support substrate 10. As mentioned above, chromium is preferably used as the material for the metal thin film 40, and chromium has a higher resistance than, for example, copper and is a relatively high-resistance conductor. However, in the subsequent second opening formation step (shown in Figure 19C), portion 40a of the metal thin film 40 is removed. As a result, a part (part 10a) of the metal support substrate 10 is exposed. Therefore, in the conductor layer formation step (shown in Figure 20A), via portions 52 that are directly connected to portion 10a of the metal support substrate 10 are formed.

[0107] Thus, according to this manufacturing method, via portions 52 in the wiring circuit board X can be formed to be directly connected to the metal support substrate 10 (the via portions 52 are not electrically connected to the metal support substrate 10 via the metal thin films 20 and 40). Therefore, this manufacturing method is suitable for achieving low-resistance electrical connections between the metal support substrate 10 and the wiring layer 71 in the wiring circuit board X.

[0108] In this manufacturing method, after the second opening formation step (shown in Figure 19C) described above, instead of the conductor layer formation step (shown in Figure 20A) and etching step (shown in Figure 20B), the conductor layer formation step described above with reference to Figures 5A and 5B may be performed, followed by the etching step described above with reference to Figure 5C. By this method, a conductor layer 50 having a laminated structure of a conductor thin film 50a and a conductor layer 50b can be formed, similar to the method described above with reference to Figures 5A to 5C.

[0109] In the wiring circuit board X, as shown in Figure 21, the metal thin film 40 may have a covering portion 42b that covers the metal support substrate 10 in contact with the through hole H. In a projection view in the thickness direction D, the covering portion 42b extends into the opening end 31 of the through hole 30A, defining an opening 40A. This opening 40A is located inside the opening 20A of the metal thin film 20.

[0110] The positional relationship between the opening 20A of the metal thin film 20, the opening ends 31 and 32 of the through hole 30A, and the opening 40A of the metal thin film 40 in a projection view in the thickness direction D of this modified example (13th modified example) of the wiring circuit board X is schematically shown below the cross-sectional view in Figure 21. In the projection view in the thickness direction D, the opening 20A overlaps with the opening end 31, and the opening 40A overlaps with the opening 20A and the opening end 32. In this modified example, in the projection view in the thickness direction D, the opening 20A and the opening end 31 substantially coincide, and the opening 40A is located within the opening end 31.

[0111] The 13th modification can be manufactured in the same manner as the manufacturing method of the 12th modification (shown in Figures 18A to 20C), except as follows: In the second opening formation step (shown in Figure 19C), an etching mask M is used which has an etching opening Ma within the opening end 31 that is smaller in diameter than the opening end 31 of the through hole 30A when viewed in projection in the thickness direction D.

[0112] Figure 22 shows the 14th modification, in which the metal support substrate 10 in the 12th modification is replaced with a metal support substrate 10'. The 14th modification can be manufactured in the same way as the 12th modification, except that a metal support substrate 10' is prepared instead of a metal support substrate 10 in the preparation step.

[0113] Figure 23 shows the 15th modification, in which the metal support substrate 10 in the 13th modification is replaced with a metal support substrate 10'. The 15th modification can be manufactured in the same manner as the 13th modification, except that a metal support substrate 10' is prepared instead of a metal support substrate 10 in the preparation step. [Explanation of symbols]

[0114] X Wiring circuit board D thickness direction 10 Metal support substrate 10a part 11 Metal support layer 12 Surface metal layer 20. Metal Thin Film (First Metal Thin Film) 20A opening (1st opening) 21 parts 30 Insulating layer 30A,H through hole 31 Opening end (1st opening end) 32 Opening end (second opening end) 33 Interior wall surface 40. Metal Thin Films (Second Metal Thin Films) 40A opening (second opening) 41 parts 50 Conductor Layers 51 Wiring section 52 Beer Club 60 Insulating layer

Claims

1. A wiring circuit board comprising, in order in the thickness direction, a metal support substrate, a first metal thin film, an insulating layer, a second metal thin film, and a conductor layer, The insulating layer has a through hole that penetrates in the thickness direction, and the through hole has a first open end on the first metal thin film side, a second open end on the opposite side of the first open end, and an inner wall surface between the first and second open ends. The first metal thin film has a first opening, and the first opening overlaps with the first opening end in a projection view in the thickness direction. The second metal thin film is disposed at least between one side of the insulating layer in the thickness direction and the conductor layer, and includes a layer made of a conductor with a higher resistance than the conductor layer, and has a second opening, the second opening overlapping the first opening and the second opening end in a projection view in the thickness direction, A wiring circuit board in which the conductor layer has via portions arranged in the through holes and connected to the metal support substrate.

2. A wiring circuit board comprising, in order in the thickness direction, a metal support substrate, a first metal thin film, an insulating layer, a second metal thin film, and a conductor layer, The insulating layer has a through hole that penetrates in the thickness direction, and the through hole has a first open end on the first metal thin film side, a second open end on the opposite side of the first open end, and an inner wall surface between the first and second open ends. The first metal thin film has a first opening, and the first opening overlaps with the first opening end in a projection view in the thickness direction. The second metal thin film has a second opening, and the second opening overlaps with the first opening and the second opening end in the projection view in the thickness direction. The conductive layer has via portions that are arranged in the through-holes and connected to the metal support substrate, The metal support substrate comprises a metal support layer and a surface metal layer disposed on the insulating layer side of the metal support layer and having a higher conductivity than the metal support layer. A wiring circuit board in which the via portion is connected to the surface metal layer.

3. The wiring circuit board according to claim 1 or 2, wherein the first opening is open along the first opening end.

4. A wiring circuit board comprising, in order in the thickness direction, a metal support substrate, a first metal thin film, an insulating layer, a second metal thin film, and a conductor layer, The insulating layer has a through hole that penetrates in the thickness direction, and the through hole has a first open end on the first metal thin film side, a second open end on the opposite side of the first open end, and an inner wall surface between the first and second open ends. The first metal thin film has a first opening, and the first opening overlaps with the first opening end in a projection view in the thickness direction. The second metal thin film has a second opening, and the second opening overlaps with the first opening and the second opening end in the projection view in the thickness direction. The conductive layer has via portions that are arranged in the through-holes and connected to the metal support substrate, A wiring circuit board in which the second metal thin film has a first covering portion on the inner wall surface.

5. The wiring circuit board according to claim 4, wherein the second opening is open on the metal support substrate along the first opening.

6. The wiring circuit board according to claim 4, wherein the second metal thin film has a second covering portion on the metal support substrate, and the second opening is located inside the first opening on the metal support substrate.

7. The wiring circuit board according to any one of claims 1 to 3, wherein the second opening is open on the insulating layer along the second opening end.

8. A wiring circuit board comprising, in order in the thickness direction, a metal support substrate, a first metal thin film, an insulating layer, a second metal thin film, and a conductor layer, The insulating layer has a through hole that penetrates in the thickness direction, and the through hole has a first open end on the first metal thin film side, a second open end on the opposite side of the first open end, and an inner wall surface between the first and second open ends. The first metal thin film has a first opening, and the first opening overlaps with the first opening end in a projection view in the thickness direction. The second metal thin film has a second opening, and the second opening overlaps with the first opening and the second opening end in the projection view in the thickness direction. The conductive layer has via portions that are arranged in the through-holes and connected to the metal support substrate, A wiring circuit board in which the second opening is formed on the insulating layer, and the second opening end is positioned within the second opening in a projection view in the thickness direction.

9. A wiring circuit board comprising, in order in the thickness direction, a metal support substrate, a first metal thin film, an insulating layer, a second metal thin film, and a conductor layer, The insulating layer has a through hole that penetrates in the thickness direction, and the through hole has a first open end on the first metal thin film side, a second open end on the opposite side of the first open end, and an inner wall surface between the first and second open ends. The first metal thin film has a first opening, and the first opening overlaps with the first opening end in a projection view in the thickness direction. The second metal thin film has a second opening, and the second opening overlaps with the first opening and the second opening end in the projection view in the thickness direction. The conductive layer has via portions that are arranged in the through-holes and connected to the metal support substrate, The first metal thin film has an extension that extends into the first opening end in a projection view in the thickness direction and defines the first opening, A wiring circuit board in which the second metal thin film has a first covering portion on the inner wall surface and a second covering portion on the extension portion, and the second opening opens along the first opening.

10. A first metal thin film formation step in which a first metal thin film is formed on one surface in the thickness direction of a metal support substrate, An insulating layer forming step, in which an insulating layer having a through hole on one surface in the thickness direction of the first metal thin film, having a first open end on the side of the first metal thin film, a second open end on the opposite side of the first open end, and an inner wall surface between the first and second open ends, A second metal thin film formation step is to form a second metal thin film on one surface in the thickness direction of the insulating layer, on the inner wall surface of the through hole, and on the first metal thin film exposed by the through hole. An opening formation step is to form openings in the first metal thin film and the second metal thin film that overlap with the first and second opening ends in a projection view in the thickness direction, thereby exposing the metal support substrate through the through holes. A method for manufacturing a wiring circuit board, comprising a conductor layer formation step of forming a conductor layer on one surface in the thickness direction of the second metal thin film formed on one surface in the thickness direction of the insulating layer, on one surface in the thickness direction of the second metal thin film formed on the inner wall surface of the through hole, and on the metal support substrate exposed by the through hole.

11. A first metal thin film formation step in which a first metal thin film is formed on one surface in the thickness direction of a metal support substrate, An insulating layer forming step, in which an insulating layer having a through hole on one surface in the thickness direction of the first metal thin film, having a first open end on the side of the first metal thin film, a second open end on the opposite side of the first open end, and an inner wall surface between the first and second open ends, A first opening forming step is to form a first opening in the first metal thin film that opens along the first open end, and expose the metal support substrate through the through hole, A second metal thin film formation step is performed, in which a second metal thin film is formed on one surface in the thickness direction of the insulating layer, on the inner wall surface of the through hole, and on the metal support substrate exposed by the through hole. A second opening formation step is to form a second opening in the second metal thin film that overlaps with the first opening and the second opening end in a projection view in the thickness direction, and expose the metal support substrate through the through hole, A method for manufacturing a wiring circuit board, comprising a conductor layer formation step of forming a conductor layer on one surface in the thickness direction of the second metal thin film formed on one surface in the thickness direction of the insulating layer, on one surface in the thickness direction of the second metal thin film formed on the inner wall surface of the through hole, and on the metal support substrate exposed by the through hole.

Images