Wiring circuit board

Abstract

A wiring circuit substrate (X) has, in the thickness direction, a metal support base material (10), an insulating layer (20), and a conductor layer (30) in this order, and has an end edge portion (E) extending in a first direction (D1). The end edge portion (E) includes a main configuration portion (E1) and partially includes a partial configuration portion (E2). In the main configuration portion (E1), the metal support base material (10) has a base material overhang portion (11) that overhangs the insulating layer (20) outward in a second direction (D2) orthogonal to the first direction (D1) and the thickness direction. In the partial configuration portion (E2), the insulating layer (20) has an insulating layer overhang portion (21) that overhangs the metal support base material (10) outward in the second direction (D2).

Description

Technical Field

[0001] This invention relates to a wiring circuit board. Background Technology

[0002] A wiring circuit board having a metal support substrate as a support substrate is known. For example, it is a suspended board with circuitry assembled in a hard disk drive or the like. The wiring circuit board with the metal support substrate has an insulating layer on the metal support substrate, and a conductor layer with a predetermined pattern on the insulating layer. The conductor layer includes, for example, a ground pattern (which is electrically connected to the metal support substrate via a passage penetrating the insulating layer in the thickness direction) and a wiring pattern (in the final manufactured wiring circuit board, this wiring pattern is not electrically connected to the metal support substrate). The wiring pattern includes multiple wires with terminal portions at their ends. Multiple terminal portions constituting one end of the multiple wires are arranged, for example, along an end edge extending in a predetermined direction along the insulating layer on the metal support substrate.

[0003] In the manufacturing process of such a wiring circuit board, for example, an insulating layer is formed on a metal support substrate, and the aforementioned conductor layer is formed on the insulating layer. During the conductor layer formation process, while forming each wiring on the insulating layer, leads for electroless plating are also formed. These leads extend from the terminal portion of the wiring, pass over one end edge of the insulating layer, and reach the metal support substrate (the metal support substrate has a portion extending outward from the one end edge of the insulating layer thereon). Furthermore, tin, nickel, or other coatings are formed on the surfaces of the wiring pattern and the ground pattern through electroless plating. During this electroless plating process, since each wiring is electrically connected to the metal support substrate via leads, the surface potential of the wiring pattern and the surface potential of the ground pattern are equal, forming a homogeneous coating on both pattern surfaces. After the electroless plating process, to electrically separate the wiring from the metal support substrate, each lead is cut off, for example, by localized etching (lead cutting process).

[0004] The technology relating to the wiring circuit board and its manufacturing method as described above is described, for example, in the following Patent Document 1.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2002-20898 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] However, in the past, there have been instances where the leads were not adequately cut during the lead-cutting process. Specifically, even after etching of the specified portions of each lead extending from the terminal portion on the insulating layer, across the end face (side surface) of one end edge of the insulating layer, and onto the portion of the metal support substrate that extends outward beyond that end edge (substrate extension), residue of the lead-forming material may still be present at these portions. In such cases, there is a defect in manufacturing a wiring circuit board with wiring that creates a short circuit with the metal support substrate.

[0010] As a countermeasure to avoid such an undesirable situation, the substrate protrusion of the metal support substrate and its vicinity are etched away along the entire area of ​​one end edge of the insulating layer in the aforementioned predetermined direction, so as to intentionally make the end face of the metal support substrate recede inward from the end face of the aforementioned end edge of the insulating layer. By removing the end of the metal support substrate in this way, the aforementioned end edge of the insulating layer protrudes outward from the metal support substrate throughout the entire area of ​​the aforementioned predetermined direction, thereby ensuring electrical separation of the wiring from the metal support substrate. However, this creates a new undesirable situation where the protruding end edge of the insulating layer is prone to bending. The easy bending of the end edge of the insulating layer can lead to the insulating layer peeling off from the metal support substrate and cause poor shape, and is therefore not preferred.

[0011] The present invention provides a wiring circuit board having a metal support substrate, an insulating layer and a conductor layer in sequence. The wiring circuit board is adapted to avoid short circuits between the conductor layer and the metal support substrate in the final manufactured product caused by the temporary formation of wires extending from the conductor layer and passing over the edge of the insulating layer to reach the metal support substrate, and is adapted to suppress bending at the edge of the insulating layer.

[0012] Solution for solving the problem

[0013] The present invention [1] provides a wiring circuit board having a metal support substrate, an insulating layer and a conductor layer sequentially in the thickness direction. The wiring circuit board is characterized by having an end edge extending in a first direction, the end edge including a main structural portion and partially including a partial structural portion. The main structural portion has a substrate protrusion formed by the metal support substrate extending outward from the insulating layer in a second direction orthogonal to the first direction and the thickness direction. The partial structural portion has an insulating layer protrusion formed by the insulating layer extending outward from the metal support substrate in the second direction. Based on the wiring circuit board described in [1], the present invention [2] further includes a conductor layer containing a terminal portion with remaining leads. This terminal portion with remaining leads is located opposite the insulating layer protrusion in the second direction and has remaining leads protruding towards the insulating layer protrusion.

[0014] Based on the wiring circuit board described in [1] or [2] above, the present invention [3] includes a plurality of terminal portions arranged separately from each other in the first direction, the plurality of terminal portions including terminal portions with lead wire remaining portions, the terminal portions with lead wire remaining portions being located in the second direction opposite to the insulating layer protrusion portion, and having lead wire remaining portions protruding toward the insulating layer protrusion portion side.

[0015] Based on the wiring circuit board described in any one of [1] to [3] above, the main structure portion of the present invention [4] includes a first main structure portion and a second main structure portion separated in the first direction, and in the end edge portion, the partial structure portion is located between the first main structure portion and the second main structure portion.

[0016] Based on the wiring circuit board described in [4] above, the present invention [5] has a first boundary structure between the first main structure and the partial structure, and a second boundary structure between the second main structure and the partial structure. In the first boundary structure, the end face of the metal support substrate in the second direction and the end face of the insulating layer in the second direction are flush in the thickness direction. In the second boundary structure, the end face of the metal support substrate in the second direction and the end face of the insulating layer in the second direction are flush in the thickness direction. The end faces of the substrate protrusion of the first main structure and the substrate protrusion of the second main structure in the second direction, the end faces of the metal support substrate and the insulating layer in the second direction of the first boundary structure, the end faces of the metal support substrate and the insulating layer in the second direction of the second boundary structure, and the end faces of the insulating layer in the second direction of the partial structure are flush in the entire first direction.

[0017] Based on the wiring circuit board described in [4] above, the end faces of the insulating layer of the first main structure and the insulating layer of the second main structure in the second direction, and the end faces of the insulating layer protrusion of the partial structure in the second direction are flush with each other in the first direction.

[0018] Based on the wiring circuit board described in [4] above, the end faces of the substrate protrusion of the first main structure and the substrate protrusion of the second main structure in the second direction, and the end face of the metal support substrate of the partial structure in the second direction are flush with each other in the first direction.

[0019] The effects of the invention

[0020] In the wiring circuit board of the present invention, as described above, a portion of the end edge extending along the first direction includes a partial structure in the first direction, wherein the insulating layer has an insulating layer protrusion that extends outward from the metal support substrate in the second direction (orthogonal to the first direction and the thickness direction). This partial structure is suitable for temporarily forming, during the manufacturing process of the wiring circuit board, a lead extending from the wiring contained in the conductor layer formed on the insulating layer and passing over the end edge of the insulating layer to reach the metal support substrate, and then, for example, by partially removing the lead, thereby achieving electrical separation between the wiring and the metal support substrate. That is, the wiring circuit board having such a partial structure is suitable for avoiding short circuits between the metal support substrate and the wiring in the final manufactured product caused by the temporary formation of a lead extending from the wiring and passing over the end edge of the insulating layer to reach the metal support substrate.

[0021] In this wiring circuit board, as described above, the edge portion extending along the first direction includes not only a partial structural portion but also a main structural portion. In this main structural portion, the metal support substrate has a substrate protrusion that extends outward from the insulating layer in the second direction. Compared to a structure in which the insulating layer extends outward from the metal support substrate over, for example, the entire area of ​​the edge portion of the wiring circuit board in the first direction, this structure is suitable for suppressing bending at the edge portion of the insulating layer at the edge portion of the wiring circuit board. Attached Figure Description

[0022] Figure 1 This is a partial top view of one embodiment of the wiring circuit board of the present invention.

[0023] Figure 2 It is along Figure 1 The cross-sectional view along line II-II shown.

[0024] Figure 3 It is along Figure 1 The cross-sectional view along line III-III shown.

[0025] Figure 4 It is along Figure 1 The cross-sectional view shown along line IV-IV.

[0026] Figure 5 It is along Figure 1 The cross-sectional view of the VV line shown.

[0027] Figure 6 With equivalent to Figure 4 To represent the change in cross section Figure 1 This is a part of the manufacturing process of the wiring circuit board shown. Figure 6 A represents the preparation process. Figure 6B indicates the first insulation layer formation process. Figure 6 C represents the conductor layer formation process.

[0028] Figure 7 Indicates the following Figure 6 The process following the process shown. Figure 7 A represents the electroless plating process. Figure 7 B indicates the second insulation layer formation process. Figure 7 C indicates the chemical coating removal process.

[0029] Figure 8 Indicates the following Figure 7 The process following the process shown. Figure 8 A represents the resist film formation process. Figure 8 B indicates the wet etching process. Figure 8 C indicates the process of removing the resist film.

[0030] Figure 9 yes Figure 6 A partial top view of the first insulating layer forming process shown in Figure B.

[0031] Figure 10 yes Figure 6 The diagram shown in C is a partial top view after the conductor layer formation process.

[0032] Figure 11 It contains by Figure 8 A top view of the first resist film formed in the resist film formation process shown in Figure A.

[0033] Figure 12 It contains by Figure 8 A top view of the second resist film formed in the resist film formation process shown in Figure A.

[0034] Figure 13 yes Figure 1 A partial top view of a modified example of the wiring circuit board shown. In this modified example, the insulating layer at the edge of the wiring circuit board is flush with the first main structure portion, the partial structure portion, and the second main structure portion arranged in the first direction. The metal support substrate extends outward from the insulating layer in the first main structure portion and the second main structure portion, and is recessed inward from the insulating layer in the partial structure portion.

[0035] Figure 14 It is along Figure 13 The cross-sectional view of line XIV-XIV shown.

[0036] Figure 15 It is along Figure 13 The cross-sectional view of the XV-XV line shown.

[0037] Figure 16 yes Figure 1A partial top view of another variation of the wiring circuit board shown. In this variation, the metal support substrate at the edge of the wiring circuit board is flush with the first main structure, the partial structure, and the second main structure arranged in the first direction. The insulating layer is recessed inward from the metal support substrate in the first and second main structures, and extends outward from the metal support substrate in the partial structure.

[0038] Figure 17 It is along Figure 16 A cross-sectional view of line XVII-XVII shown.

[0039] Figure 18 It is along Figure 16 The cross-sectional view of line XVIII-XVIII shown. Detailed Implementation

[0040] Figures 1-5 Wiring circuit board X represents one embodiment of the wiring circuit board of the present invention. Figure 1 This is a partial top view of the wiring circuit board X. Figure 2 It is along Figure 1 The cross-sectional view along line II-II shown. Figure 3 It is along Figure 1 The cross-sectional view along line III-III shown. Figure 4 It is along Figure 1 The cross-sectional view shown along line IV-IV. Figure 5 It is along Figure 1 The cross-sectional view of the VV line shown.

[0041] like Figures 2-5 As shown, the wiring circuit board X has a metal support substrate 10, an insulating layer 20 as a base insulating layer and a conductor layer 30 in sequence in the thickness direction. In this embodiment, the insulating layer 20 also has an insulating layer 40 as a covering insulating layer covering the conductor layer 30.

[0042] In addition, such as Figure 1 As shown, the wiring circuit board X has a partial end edge E at its periphery, which is arranged along the terminal row L described later. Figure 1 This is a top view of the edge portion E of the wiring circuit board X and its vicinity. The edge portion E extends in a direction such that it defines a portion of the outline of the wiring circuit board X. The direction in which the edge portion E extends is referred to as the first direction D1. The wiring circuit board X preferably has a plurality of edge portions E. Alternatively, the wiring circuit board X may also have a predetermined number of edge portions E continuously in the first direction D1.

[0043] The metal support substrate 10 is a necessary component for ensuring the mechanical strength of the wiring circuit board X. In this embodiment, the metal support substrate 10 has a predetermined top view shape.

[0044] Materials used as the metal support substrate 10 include, for example, metal foil. Metal materials used as metal foils include, for example, copper, copper alloys, stainless steel, and 42 alloy. Stainless steel, for example, is SUS304 based on AISI (American Iron and Steel Institute) standards.

[0045] The thickness of the metal support substrate 10 is, for example, 10 μm or more, preferably 15 μm or more, more preferably 50 μm or more, and for example, 500 μm or less, preferably 300 μm or less.

[0046] like Figures 2-5 As shown, the insulating layer 20 is located on one side of the metal support substrate 10 in the thickness direction. In this embodiment, the insulating layer 20 is located on one side of the metal support substrate 10 in the thickness direction.

[0047] Examples of materials that can be used as insulating layer 20 include resins such as polyimide, polyether nitrile, polyether sulfone, polyethylene terephthalate, polyethylene naphthalate, and polyvinyl chloride (the same resins can also be used as materials for insulating layer 40, which will be described later).

[0048] The thickness of the insulating layer 20 is, for example, 1 μm or more, preferably 3 μm or more, and also, for example, 35 μm or less, preferably 15 μm or less.

[0049] like Figure 1 As shown, the end edge E includes a main structural part E1 and partially includes a partial structural part E2. Specifically, in this embodiment, the end edge E includes a main structural part E1, a partial structural part E2, and a boundary structural part E3. The main structural part E1 includes a first main structural part E1a and a second main structural part E1b separated in the first direction D1. The partial structural part E2 is located between the first main structural part E1a and the second main structural part E1b in the first direction D1. The boundary structural part E3 includes a first boundary structural part E3a and a second boundary structural part E3b. The first boundary structural part E3a is located between the first main structural part E1a and the partial structural part E2 in the first direction D1. The second boundary structural part E3b is located between the partial structural part E2 and the second main structural part E1b in the first direction D1.

[0050] In the main structural section E1 (first main structural section E1a, second main structural section E1b), as follows Figure 3As shown, the metal support substrate 10 has a substrate protrusion 11 extending outward from the insulating layer 20 in the second direction D2 (a direction orthogonal to the first direction D1 and the thickness direction). This protrusion is 11a in the first main structural section E1a and 11b in the second main structural section E1b. Specifically, in the main structural section E1, the end face 12 of the metal support substrate 10, which serves as a substrate side surface (end face 12a in the first main structural section E1a and end face 12b in the second main structural section E1b), is located outward from the end face 22 of the insulating layer 20, which serves as an insulating layer side surface (end face 22a in the first main structural section E1a and end face 22b in the second main structural section E1b), in the second direction D2. The extension length of the substrate protrusion 11 in the second direction D2 is, for example, 3 μm or more, preferably 5 μm or more, and also, for example, 200 μm or less, preferably 100 μm or less (this extension length of the substrate protrusion 11 is also the same in the modified examples described later).

[0051] In some structural parts E2, such as Figure 4 As shown, the insulating layer 20 has an insulating layer protrusion 21 that extends outward from the metal support substrate 10 in the second direction D2. That is, in the partial structure E2, the end face 22 of the insulating layer 20 (end face 22c in the partial structure E2) is located outward from the end face 12 of the metal support substrate 10 (end face 12c in the partial structure E2) in the second direction D2. The extension length of the insulating layer protrusion 21 in the second direction D2 is, for example, 3 μm or more, preferably 5 μm or more, and also, for example, 200 μm or less, preferably 100 μm or less (this extension length of the insulating layer protrusion 21 is also the same in the modified examples described later).

[0052] In boundary structure section E3 (first boundary structure section E3a, second boundary structure section E3b), such as Figure 5 As shown, the end face 12 on the second direction D2 of the metal support substrate 10 (end face 12d in the first boundary structure E3a and end face 12e in the second boundary structure E3b) and the end face 22 on the second direction D2 of the insulating layer 20 (end face 22d in the first boundary structure E3a and end face 22e in the second boundary structure E3b) are flush in the thickness direction. In this embodiment, the first boundary structure E3a and the second boundary structure E3b, where the end faces 12 and 22 are flush in the thickness direction, each have a shape that extends along the first direction D1.

[0053] In addition, in this embodiment, Figure 1In the top view shown, the end face 12a of the metal support substrate 10 (substrate extension 11a) of the first main structural part E1a, the end face 12d of the metal support substrate 10 and the end face 22d of the insulating layer 20 of the first boundary structural part E3a, the end face 22c of the insulating layer 20 of the partial structural part E2, the end face 12e of the metal support substrate 10 and the end face 22e of the insulating layer 20 of the second boundary structural part E3b, and the end face 12b of the metal support substrate 10 (substrate extension 11b) of the second main structural part E1b are flush with each other in the entire first direction D1.

[0054] In this structure, in the first boundary structure E3a and the second boundary structure E3b, the insulating layer 20 is in contact with the metal support substrate 10 and is directly supported. The two ends of the insulating layer protrusion 21 of the partial structure E2 in the first direction D1 are continuous with and supported by the insulating layer 20 of the boundary structures E3a and E3b. That is, the two ends of the insulating layer protrusion 21 of the partial structure E2 in the first direction D1 are continuous with and supported by the insulating layer 20 that is in contact with the metal support substrate 10. Therefore, bending of the insulating layer protrusion 21 can be suppressed.

[0055] In the wiring circuit board X, the first boundary structure portion E3a and the second boundary structure portion E3b, which are flush with the end face 12 and the end face 22 in the thickness direction, may not have the form of extending in the first direction D1, but have the form of forming the boundary line between the main structure portion E1 and the partial structure portion E2.

[0056] The conductor layer 30 includes a plurality of terminal portions 31, a plurality of signal wirings 32, and a plurality of ground wires 33, and is located on one side of the insulating layer 20 in the thickness direction. In this embodiment, the conductor layer 30 is located on the surface of the insulating layer 20 on one side in the thickness direction.

[0057] Multiple terminal portions 31 are arranged separately along the edge portion E in the first direction D1 and form a terminal row L (an illustrative map shows the terminal row L comprising three terminal portions 31, with two signal wirings 32 and a ground wire 33 extending from these terminal portions 31). In the terminal row L arranged along the edge portion E, the distance between adjacent terminal portions 31 is, for example, 10 μm or more, and also, for example, 1000 μm or less.

[0058] The terminal section L includes a plurality of terminal sections 31, including a terminal section 31A with a lead wire remainder. The terminal section 31A with the lead wire remainder is located in the second direction D2 opposite to the insulating layer protrusion 21, and has a terminal section body 31a and a lead wire remainder 34a. The terminal section body 31a has a connection disc shape wider than the width of the signal wiring 32 (the terminal sections 31 themselves, except for terminal section 31A, have a connection disc shape wider than the width of the signal wiring 32). The lead wire remainder 34a protrudes from the edge E side of the terminal section body 31a in the second direction D2 toward the edge E. The lead wire remainder 34a is part of a lead 34 (a lead for chemical plating) temporarily formed during the manufacturing process of the wiring circuit board X, as described later. The protruding length of the lead wire remainder 34a is, for example, 5 μm or more, and also, for example, 1000 μm or less.

[0059] Each signal wiring 32 has a predetermined pattern shape on the insulating layer 20. Figure 1 One end of the signal wiring 32 shown in the partial top view is connected to the terminal portion 31 included in the terminal portion row L (in Figure 1 In the diagram, the portion of the signal wiring 32 covered by the insulating layer 40 (described later) is indicated by a dashed line. The other end of the signal wiring 32 is connected to one of the terminal portions 31 (not shown) that are not included in the terminal portion column L.

[0060] The thickness of the signal wiring 32 is, for example, 3 μm or more, preferably 5 μm or more, and also, for example, 50 μm or less, preferably 30 μm or less. The width of the signal wiring 32 (the dimension in the direction orthogonal to the extension direction of the signal wiring 32) is, for example, 5 μm or more, preferably 8 μm or more, and also, for example, 100 μm or less, preferably 50 μm or less.

[0061] The grounding wire 33 has a predetermined pattern shape on the insulating layer 20. Figure 1 One end of the grounding wire 33 shown in the partial top view is connected to the terminal portion 31 included in the terminal portion row L (in Figure 1 In the diagram, the portion of the grounding wire 33 covered by the insulating layer 40 (described later) is indicated by dashed lines. The other end of the grounding wire 33 is connected to one of the terminal portions 31 (not shown) not included in terminal portion L. This terminal portion 31 is electrically connected to the metal support substrate 10 via a passage (not shown) penetrating the insulating layer 20 in the thickness direction of the insulating layer 20. The grounding wire 33 is electrically connected to the metal support substrate 10 via such a terminal portion 31.

[0062] The thickness of the grounding wire 33 is, for example, 3 μm or more, preferably 5 μm or more, and also, for example, 50 μm or less, preferably 30 μm or less. The width of the grounding wire 33 (the dimension in the direction orthogonal to the extension direction of the grounding wire 33) is, for example, 5 μm or more, preferably 8 μm or more, and also, for example, 100 μm or less, preferably 50 μm or less.

[0063] Materials used for conductor layer 30 include, for example, copper, silver, gold, solder, or alloys thereof, with copper being preferred.

[0064] like Figures 2-4 As shown, the main surfaces of the signal wiring 32 and grounding wire 33 of the conductor layer 30, except for the surface in contact with the insulating layer 20, are covered by a coating C. The coating C is a plating formed by a chemical plating process described later. The coating C has the function of ensuring the tightness between the conductor layer 30 and the insulating layer 40 and preventing so-called migration in the conductor layer 30. Examples of materials for the coating C include nickel and tin, with nickel being preferred. Furthermore, the thickness of the coating C is, for example, 0.01 μm or more, and also, for example, 1 μm or less. The insulating layer 40 is disposed on one side of the insulating layer 20 in the thickness direction, covering the signal wiring 32 and the grounding wire 33, and the insulating layer 40 has a predetermined pattern shape. The insulating layer 40 does not cover the terminal portion 31, and the grounding wire 33 is exposed.

[0065] The height of insulation layer 40 from insulation layer 20 (in) Figures 2-4 The distance from the top of the insulating layer 20 to the insulating layer 40 in the figure is greater than the total thickness of the conductor layer 30 and the coating C on its surface, for example, 5 μm or more, preferably 7 μm or more, and for example, 70 μm or less, preferably 50 μm or less.

[0066] Figures 6-8 This is an example of a method for manufacturing a wiring circuit board X. Figures 6-8 With equivalent to Figure 4 The manufacturing method is represented by the change in the cross-section.

[0067] In this manufacturing method, firstly, as Figure 6 As shown in Figure A, a metal substrate 10A is prepared (preparation process). The metal substrate 10A is a substrate that will be formed into a metal support substrate 10 by the shape processing described later, and has a first surface 10a and a second surface 10b on the opposite side therefrom.

[0068] Next, as Figure 6 B and Figure 9As shown, an insulating layer 20 is patterned and formed on the first surface 10a of a metal substrate 10A (first insulating layer formation process). The insulating layer 20 is formed to have a protrusion 23, which is included in the wiring circuit board X, which is the final manufactured product, and becomes the insulating layer protrusion 21. In addition, the insulating layer 20 has through holes (not shown) at specified locations to form the aforementioned passages.

[0069] In this process, firstly, a solution of photosensitive resin (varnish) is applied to the first surface 10a of the metal substrate 10A and dried to form a coating film. Next, this coating film on the metal substrate 10A undergoes exposure through a specified mask, followed by development, and then baking as needed. This forms an insulating layer 20 on the metal substrate 10A. After these stages of the process, such as... Figure 9 As shown, the metal substrate 10A has a substrate protrusion 13 that extends outward from the insulating layer 20 in the second direction D2. The substrate protrusion 13 extends outward from the insulating layer 20 over the entire area in the first direction D1 at the edge portion E to be formed in the wiring circuit board X. Next, as... Figure 6 C and Figure 10 As shown, a conductor layer 30A is formed on the insulating layer 20 and the metal substrate 10A (conductor layer formation process). In addition to the aforementioned terminal portion 31 (including terminal portion 31A), signal wiring 32, and grounding wire 33, the conductor layer 30A also includes a lead 34. The lead 34 extends from the portion of the terminal portion 31A opposite to the portion connected to the signal wiring 32 on the insulating layer 20, and extends beyond the second direction D2 end of the protrusion 23 in the insulating layer 20 to reach the substrate protrusion 13. In this embodiment, the lead 34 has a pad portion 34b on the metal substrate 10A that is circular when viewed from above. The terminal portion 31A and the signal wiring 32 connected thereto are electrically connected to the metal substrate 10A via the lead 34. Figure 10 Another signal wiring 32 shown is connected to one of the unshown terminal portions 31A (first terminal portion 31, not shown) not included in terminal portion L. This terminal portion 31A is electrically connected to the metal substrate 10A via another lead 34. Preferably, this other lead 34 extends from the unshown terminal portion 31A on the insulating layer 20, and passes beyond the same protrusion as the protrusion 23 in the insulating layer 20 to reach the same substrate protrusion as the substrate protrusion 13. In addition, the ground wire 33 is electrically connected to the metal substrate 10A via the aforementioned second terminal portion 31 and the aforementioned passage.

[0070] In the conductor layer formation process, firstly, a seed layer is formed by, for example, sputtering, to cover the first surface 10a of the metal substrate 10A and the insulating layer 20 thereon. Examples of materials for the seed layer include Cr, Cu, Ni, Ti, and their alloys. Next, a resist pattern is formed on the seed layer. The resist pattern has openings with a shape corresponding to the pattern shape of the conductor layer 30A. In the formation of the resist pattern, for example, after forming a resist film by bonding a photosensitive resist film onto the seed layer, the resist film is subjected to exposure through a predetermined mask, followed by development, and then baking as needed. Next, a conductor material such as copper is deposited into the openings of the resist pattern using an electroplating solution. Next, the resist pattern is removed by etching. Then, the portion of the seed layer exposed due to the removal of the resist pattern is removed by etching. As described above, the conductor layer 30A can be formed.

[0071] Next, as Figure 7 As shown in Figure A, a coating C (chemical plating process) is formed by chemical plating. In this process, the coating C (chemical plating film) is formed by chemical plating with a chemical plating solution to cover the portion of the conductor layer 30A except for the surface of the conductor layer 30A that contacts the insulating layer 20 and the metal substrate 10A. The chemical plating solution contains ions of the material used to form the coating C. Examples of materials for the coating C include nickel and tin, with nickel being preferred.

[0072] In this process, each signal wiring 32 is electrically connected to the metal substrate 10A via lead 34. Therefore, the surface potentials of each signal wiring 32 and ground wire 33 (which are electrically connected to the metal support substrate 10 via a path) are equal, and a homogeneous coating C is formed on the surface of the signal wiring 32 and the surface of the ground wire 33.

[0073] Next, as Figure 7 As shown in Figure B, an insulating layer 40 is formed on the insulating layer 20, covering a predetermined portion (signal wiring 32, grounding wire 33) of the conductor layer 30A (second insulating layer formation step). In this step, firstly, a solution of photosensitive resin (varnish) is applied to the first surface 10a side of the metal substrate 10A and dried to form a coating film. Next, the coating film is subjected to exposure through a predetermined mask, followed by development, and then baking as needed. In this way, the insulating layer 40 can be formed.

[0074] Next, as Figure 7 As shown in Figure C, the exposed portions of the coating C not covered by the insulating layer 40 are removed (chemical plating removal process). The coating C is removed locally, for example, by wet etching. Examples of etching solutions used for wet etching include sulfuric acid hydrogen peroxide and nitric acid hydrogen peroxide.

[0075] Next, as Figure 8 A, Figure 11 and Figure 12 As shown, a first resist film 101 with a predetermined pattern is formed on the first surface 10a side of the metal substrate 10A, and a second resist film 102 with a predetermined pattern is formed on the second surface 10b side of the metal substrate 10A (resist film forming process). The first resist film 101 covers the portion of the conductor layer 30A on the insulating layer 20 except for the portion removed in the shaping process described later (in... Figure 11 In the diagram, the portion of the conductor layer 30A covered by the first resist film 101 is indicated by a dashed line, and the portion of the metal substrate 10A to be formed as the substrate protrusion 11 is also covered. Furthermore, the resist film 101 has a recess 101a at the location corresponding to the lead 34, for exposing a large portion of the lead 34.

[0076] Next, as Figure 8 As shown in Figure B, wet etching is used to remove areas of the metal substrate 10A and conductor layer 30A that are not covered by the first resist film 101 and the second resist film 102 (wet etching process). Specifically, the first resist film 101 and the second resist film 102 are used as etching masks, and wet etching is performed from both sides in the thickness direction. Ferric chloride is used as an etching solution for wet etching, for example.

[0077] In this process, the metal substrate 10A is shaped to form the metal support substrate 10. At the same time, a portion of the lead 34 (the end connected to the terminal portion 31A) remains as the lead remainder 34a, and another portion of the lead 34 (all the leads 34 formed) is removed and cut off. As a result, the signal wiring 32 is electrically separated from the metal support substrate 10.

[0078] Next, as Figure 8 As shown in C, the first resist film 101 and the second resist film 102 are removed, for example, by etching (resist film removal process).

[0079] For example, by going through the above-described process, a wiring circuit board X can be manufactured.

[0080] In the wiring circuit board X, as described above, a portion of the end edge E extending along the first direction D1 includes a partial structure E2 in the first direction D1. In this partial structure E2, the insulating layer 20 has an insulating layer protrusion 21 that extends outward from the metal support substrate 10 in the second direction D2. This partial structure E2 is suitable for temporarily forming, during the manufacturing process of the wiring circuit board X, a lead 34 extending from the signal wiring 32 formed on the insulating layer 20 and passing over the end of the insulating layer 20 to reach the metal support substrate 10. Figure 6C), the lead 34 is used for electroless plating ( Figure 7 A) Subsequently, for example, by partially removing the lead 34, the signal wiring 32 is electrically isolated from the metal support substrate 10. That is, the wiring circuit board X having the partial structure E2 is suitable for avoiding short circuits between the metal support substrate 10 and the signal wiring 32 in the final manufactured product caused by the temporary formation of the lead 34 extending from the signal wiring 32 and passing over the end of the insulating layer 20 to reach the metal support substrate 10.

[0081] In the wiring circuit board X, as described above, the edge portion E extending along the first direction D1 includes a partial structural portion E2 and a main structural portion E1. In this main structural portion E1, the metal support substrate 10 has a substrate protrusion 11 that extends outward from the insulating layer 20 in the second direction D2. Compared to a structure in which the insulating layer 20 extends outward from the metal support substrate 10 over, for example, the entire area of ​​the edge portion E of the wiring circuit board X in the first direction D1, such a structure is suitable for suppressing bending at the end of the insulating layer 20 in the edge portion E. From the viewpoint of suppressing the peeling of the insulating layer 20 from the metal support substrate 10 and ensuring a good shape in the edge portion E, it is preferable to suppress bending at the end of the insulating layer 20 in the edge portion E. The edge portion E of the wiring circuit board X may also have Figures 13-15 The structure shown. Figures 13-15 The shown end edge E includes: a main structural portion E1, which includes a first main structural portion E1a and a second main structural portion E1b; and a partial structural portion E2 located between the first main structural portion E1a and the second main structural portion E1b. In the main structural portion E1 (the first main structural portion E1a and the second main structural portion E1b), as... Figure 14 As shown, the metal support substrate 10 has a substrate protrusion 11 extending outward from the insulating layer 20 in the second direction D2 (the substrate protrusion 11a is in the first main structural part E1a, and the substrate protrusion 11b is in the second main structural part E1b). In a portion of the structural part E2, such as Figure 15 As shown, the insulating layer 20 has an insulating layer protrusion 21 that extends outward from the metal support substrate 10 in the second direction D2. The boundary structure portion E3 as described in the above embodiment is not included in the end edge portion E of this modified example.

[0082] In this variation, such as Figure 13As shown, the end face 22a of the insulating layer 20 in the second direction D2 of the first main structural part E1a, the end face 22b of the insulating layer 20 in the second direction D2 of the second main structural part E1b, and the end face 22c of the insulating layer protrusion 21 in the second direction D2 of the partial structural part E2 are flush with each other in the entire first direction D1. In contrast, in the first main structural part E1a and the second main structural part E1b, the metal support substrate 10 extends outward from the insulating layer 20 in the second direction D2, while in the partial structural part E2, the metal support substrate 10 is recessed inward from the insulating layer 20 in the second direction D2. Compared with the structure of the end edge E in the above embodiment, this structure makes it easier to reduce the area of ​​the insulating layer 20.

[0083] Furthermore, in this structure, in the first main structural portion E1a and the second main structural portion E1b, the insulating layer 20 is in contact with the metal support substrate 10 and is directly supported. The two ends of the insulating layer protrusion 21 of the partial structural portion E2 in the first direction D1 are continuous with and supported by the insulating layer 20 of the main structural portions E1a and E1b. That is, the two ends of the insulating layer protrusion 21 of the partial structural portion E2 in the first direction D1 are continuous with and supported by the insulating layer 20 that is in contact with the metal support substrate 10. Therefore, bending of the insulating layer protrusion 21 can be suppressed.

[0084] The edge E of the wiring circuit board X can also have Figures 16-18 The structure shown. Figures 16-18 The shown end edge E includes: a main structural portion E1, which includes a first main structural portion E1a and a second main structural portion E1b; and a partial structural portion E2 located between the first main structural portion E1a and the second main structural portion E1b. In the main structural portion E1 (the first main structural portion E1a and the second main structural portion E1b), as... Figure 17 As shown, the metal support substrate 10 has a substrate protrusion 11 extending outward from the insulating layer 20 in the second direction D2 (the substrate protrusion 11a is in the first main structural part E1a, and the substrate protrusion 11b is in the second main structural part E1b). In a portion of the structural part E2, such as Figure 18 As shown, the insulating layer 20 has an insulating layer protrusion 21 that extends outward from the metal support substrate 10 in the second direction D2. The boundary structure portion E3 as described in the above embodiment is not included in the end edge portion E of this modified example.

[0085] In this modified example, the end face 12 of the substrate protrusion 11 of the first main structural part E1a in the second direction D2, the end face 12 of the substrate protrusion 11 of the second main structural part E1b in the second direction D2, and the end face 12 of the metal support substrate 10 of the partial structural part E2 in the second direction D2 are flush with the entire first direction D1. In contrast, in the first main structural part E1a and the second main structural part E1b, the insulating layer 20 is recessed inwards from the metal support substrate 10 in the second direction D2, while in the partial structural part E2, the insulating layer 20 protrudes outwards from the metal support substrate 10 in the second direction D2. Compared with the structure of the end edge E in the above embodiment, this structure facilitates the miniaturization of the metal support substrate 10.

[0086] Compared to a structure in which the insulating layer 20 covers the entire area of ​​the edge portion E of the wiring circuit board X in, for example, the first direction D1, and extends outward from the metal support substrate 10, such a structure is also suitable for suppressing bending at the end of the insulating layer 20 at the edge portion E.

[0087] Industrial availability

[0088] The wiring circuit board of the present invention can be applied, for example, to a suspended board with circuitry assembled in the like, such as a hard disk drive.

[0089] Explanation of reference numerals in the attached figures

[0090] X, Wiring circuit board; D1, First direction; D2, Second direction; E, Edge portion; E1, Main structure portion; E1a, First main structure portion; E1b, Second main structure portion; E2, Partial structure portion; E3, Boundary structure portion; E3a, First boundary structure portion; E3b, Second boundary structure portion; 10, Metal support substrate; 11, Substrate protrusion; 12, End face; 20, 40, Insulating layer; 21, Insulating layer protrusion; 22, End face; 30, Conductor layer; 31, Terminal portion; 31A, Terminal portion with remaining lead portion; 32, Wiring; 33, Grounding wire; 34, Lead; 34a, Remaining lead portion; C, Coating.

Claims

1. A wiring circuit board, comprising, sequentially in the thickness direction, a metal support substrate, an insulating layer, and a conductor layer, characterized in that, The wiring circuit board has an end edge extending along a first direction. The end edge portion includes a main structural portion and partially includes a partial structural portion. The main structural portion has a substrate protrusion formed by the metal support substrate extending outward beyond the insulating layer in a second direction orthogonal to the first direction and the thickness direction. The partial structural portion has an insulating layer protrusion formed by the insulating layer extending outward beyond the metal support substrate in the second direction. The conductor layer includes a terminal portion with a lead remaining portion, which is located in the second direction opposite to the insulating layer protrusion and has a lead remaining portion protruding toward the insulating layer protrusion.

2. The wiring circuit board according to claim 1, characterized in that, The conductor layer includes a plurality of terminal portions arranged separately from each other in the first direction. The plurality of terminal portions include terminal portions with lead wire remainders. The terminal portions with lead wire remainders are located opposite the insulating layer protrusion in the second direction and have lead wire remainders protruding toward the insulating layer protrusion.

3. The wiring circuit board according to claim 1, characterized in that, The main structural component comprises a first main structural component and a second main structural component separated in the first direction. In the end edge portion, the partial structural portion is located between the first main structural portion and the second main structural portion.

4. The wiring circuit board according to claim 3, characterized in that, The end edge portion has a first boundary structure between the first main structural portion and the partial structural portion, and a second boundary structure between the second main structural portion and the partial structural portion. In the first boundary structure, the end face of the metal support substrate in the second direction and the end face of the insulating layer in the second direction are flush in the thickness direction. In the second boundary structure, the end face of the metal support substrate in the second direction and the end face of the insulating layer in the second direction are flush in the thickness direction. The end faces of the substrate protrusion of the first main structural part and the substrate protrusion of the second main structural part in the second direction, the end faces of the metal support substrate and the insulating layer of the first boundary structural part in the second direction, the end faces of the metal support substrate and the insulating layer of the second boundary structural part in the second direction, and the end face of the insulating layer of the partial structural part in the second direction are flush with each other in the entire first direction.

5. The wiring circuit board according to claim 3, characterized in that, The end faces of the insulating layers of the first main structural portion and the second main structural portion in the second direction, and the end faces of the insulating layer extensions of the partial structural portion in the second direction, are flush with each other in the entire first direction.

6. The wiring circuit board according to claim 3, characterized in that, The end faces of the substrate protrusions of the first main structural part and the substrate protrusions of the second main structural part in the second direction, and the end faces of the metal support substrates of the partial structural part in the second direction, are flush with each other in the entire first direction.

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