Wiring circuit board and method for manufacturing the same

Abstract

To provide a wiring circuit board having high flexibility and reduced impedance discontinuity and a manufacturing method thereof.SOLUTION: An insulating layer 30 has first and second main surfaces S1 and S2. A conductive layer 40 is provided on the first main surface S1. A metal thin film 20 is provided on the second main surface S2 and has a third main surface S3 facing in the opposite direction to the insulating layer 30. A metal support body 10 is made of a metal material different from that of the metal thin film 20. First and second regions A1 and A2 are defined on the first main surface S1 and the conductive layer 40 constitutes a wiring extending to pass through the first and second regions A1 and A2 on the first main surface S1. In the third main surface S3, when defining third and fourth regions A3 and A4 that overlap the first and second regions A1 and A2 of the first main surface S1 in plan view, the metal support body 10 is provided on the third main surface S3 so as not to cover the third region A3 and to cover the fourth region A4.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] As an example of a wiring circuit board, there is a circuit-equipped suspension board in which an insulating layer is formed on a metal support board, and a conductor layer as wiring is formed on the insulating layer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In recent years, the uses of wiring circuit boards have been expanding. Depending on the use of the wiring circuit board, higher flexibility may be required for the wiring circuit board. In the above circuit-equipped suspension board, the metal support board has relatively high rigidity compared to the insulating layer and the conductor layer. Therefore, it is considered that a wiring circuit board having high flexibility can be realized by removing a part of the metal support board from the above basic configuration of the circuit-equipped suspension board.

[0005] In a portion of the above circuit-equipped suspension board where the conductor layer and the metal support board face each other with the insulating layer interposed therebetween, the metal support board reduces the impedance of the conductor layer (wiring). Therefore, when a part of the metal support board is removed, the impedance of the conductor layer cannot be reduced. In this case, impedance mismatch may occur between the conductor layer and an electronic component connected to the conductor layer due to the impedance of the conductor layer (wiring) deviating from the desired value.

[0006] Patent Document 1 describes an example of a suspension flexure substrate (wiring circuit board) in which an insulating layer and wiring are laminated in that order on a stainless steel metal support substrate having an opening region. In the following description, the direction in which the metal support substrate, insulating layer and wiring are laminated in the suspension flexure substrate of Patent Document 1 will be referred to as the substrate lamination direction.

[0007] In this suspension flexure substrate, the opening region of the metal support substrate overlaps with a portion of the wiring in the substrate stacking direction. Furthermore, in this suspension flexure substrate, a conductive film with higher conductivity than the metal support substrate is formed in the opening region of the metal support substrate to reduce the impedance of the wiring. This conductive film overlaps with a portion of the wiring in the substrate stacking direction.

[0008] In this configuration, multiple portions of the wiring overlap the metal support substrate or the conductive film in the substrate stacking direction. This reduces the impedance of the wiring. However, in the suspension flexure substrate of Patent Document 1, the metal support substrate and the conductive film are made of materials with at least different conductivity (electrical conductivity).

[0009] The degree to which impedance can be reduced across multiple parts of the above wiring depends on the conductivity of the opposing components (in the above example, the conductive film and the metal support substrate) separated by an insulating layer in the substrate stacking direction. Therefore, there is a difference in the degree of impedance reduction between a portion of the wiring that overlaps the conductive film in the substrate stacking direction and other portions of the wiring that overlap the metal support substrate in the substrate stacking direction. Discrepancies in impedance in the wiring degrade the electrical characteristics of that wiring.

[0010] The object of the present invention is to provide a wiring circuit board that has high flexibility and reduced impedance discontinuities, and a method for manufacturing the same. [Means for solving the problem]

[0011] (1) A wiring circuit board according to one aspect of the present invention comprises an insulating layer having a first main surface and a second main surface facing opposite directions, a conductor layer provided on the first main surface of the insulating layer, and the insulating layer So as to cover the entire second main surface, The device comprises a metal thin film provided on a second main surface and having a third main surface facing in the opposite direction to the insulating layer, and a metal support made of a metal material different from at least a portion of the metal material of the metal thin film, wherein the first main surface of the insulating layer has two distinct first and second regions, and at least a portion of the conductor layer constitutes wiring extending through the first and second regions of the first main surface, and the third main surface of the metal thin film defines a third region and a fourth region that overlap the first and second regions of the first main surface, respectively, when viewed in a direction perpendicular to the first main surface, the metal support is provided on the third main surface such that it does not cover the third region of the third main surface but covers the fourth region.

[0012] In this wiring circuit board, the portion of the wiring circuit board that overlaps with the first region of the first main surface and the third region of the third main surface when viewed in the intersecting direction is called the first substrate portion. The other portion of the wiring circuit board that overlaps with the second region of the first main surface and the fourth region of the third main surface when viewed in the intersecting direction is called the second substrate portion.

[0013] In this case, the first substrate portion includes a portion of the conductor layer, a portion of the insulating layer, and a portion of the metal thin film, but does not include a metal support. On the other hand, the second substrate portion includes the other portion of the conductor layer, the other portion of the insulating layer, the other portion of the metal thin film, and a metal support.

[0014] As described above, the first substrate portion does not include a metal support. As a result, the first substrate portion has higher flexibility compared to the second substrate portion. On the other hand, the second substrate portion includes a metal support. As a result, the second substrate portion has a certain level of mechanical strength necessary to support the first substrate portion on other components or to mount other components.

[0015] Furthermore, in the above-described wiring circuit board, a thin metal film is positioned opposite each of the wiring formed in the first region of the first main surface and the wiring formed in the second region of the first main surface, with an insulating layer in between. As a result, the impedance of one part of the conductor layer and the impedance of the other part of the conductor layer are adjusted by the common thin metal film. Therefore, the uneven adjustment of impedance across multiple parts of the conductor layer is reduced.

[0016] As a result, a wiring circuit board with high flexibility and reduced impedance discontinuities is realized.

[0017] (2) On the first main surface, the first region and the second region may be adjacent to each other. In this case, the first substrate portion and the second substrate portion are arranged in a continuous line, so that the first substrate portion is properly supported by the second substrate portion.

[0018] (3) The metal thin film includes a first metal film and a second metal film stacked in intersecting directions, and at least one of the metal materials of the first metal film and the second metal film may be different from the metal material of the metal support.

[0019] In this case, a first metal film and a second metal film are used as the metal thin film. Therefore, by appropriately determining the metal materials used for the first and second metal films, a more suitable metal thin film can be formed to reduce the impedance of the conductor layer. Alternatively, a more suitable metal thin film can be formed to improve the adhesion between the metal thin film and the metal support to the insulating layer.

[0020] (4) The metal thin film may include a plating layer. The degree of reduction in the impedance of the conductor layer varies depending on the thickness of the metal thin film. According to the above configuration, at least a portion of the metal thin film includes a plating layer. When forming a plating layer, the thickness of the formed plating layer can be adjusted relatively easily by appropriately adjusting the plating processing conditions such as processing time. Therefore, it becomes possible to form a metal thin film with a more appropriate thickness for reducing the impedance of the conductor layer.

[0021] (5) The thickness of the metal thin film may be smaller than the thickness of the metal support. In this case, higher flexibility is ensured in the first substrate portion.

[0022] (6) The thickness of the metal thin film may be 20 nm or more and 5 μm or less. In this case, the impedance of the conductor layers formed on the first substrate portion and the second substrate portion is more appropriately adjusted. (7) A wiring circuit board according to another aspect of the present invention comprises an insulating layer having a first main surface and a second main surface facing opposite directions, a conductor layer provided on the first main surface of the insulating layer, a metal thin film provided on the second main surface of the insulating layer and having a third main surface facing opposite directions from the insulating layer, and a metal support made of a metal material different from at least a portion of the metal material of the metal thin film, wherein the first main surface of the insulating layer has a first region, a second region and a third region which are different from each other, the first region and the second region which are adjacent, the first region and the third region which are adjacent, and the first region and the third region which are spaced apart, and at least one of the conductor layers The part constitutes wiring that extends through the first, second, and third regions of the first main surface in that order, and when the third main surface of the metal thin film is defined as having a fourth, fifth, and sixth region that overlap the first, second, and third regions of the first main surface when viewed in an intersecting direction perpendicular to the first main surface, the metal support is provided on the third main surface such that it does not cover the fifth region of the third main surface but covers the fourth and sixth regions, and the portion of the metal support that covers the fourth region of the metal thin film and the portion of the metal support that covers the sixth region of the metal thin film are spaced apart from each other.

[0023] ( 8 ) A method for manufacturing a wiring circuit board according to another aspect of the present invention includes a step of preparing a metal support, a step of forming a metal thin film made of a metal material different from the metal support on the metal support, and an insulating layer having a first main surface and a second main surface facing opposite directions, on the second main surface moreover forming on the metal thin film so that it contacts the metal thin film, a step of forming a conductor layer on the first main surface of the insulating layer, and a step of removing a part of the metal support after the step of forming the metal thin film. On the first main surface of the insulating layer, a first region and a second region different from each other are defined. The step of forming the conductor layer includes forming a wiring extending through the first region and the second region of the first main surface by at least a part of the conductor layer. The metal thin film has a third main surface facing in a direction opposite to the insulating layer and contacting the metal support. When a third region and a fourth region overlapping the first region and the second region of the first main surface are defined on the third main surface of the metal thin film in the crossing direction orthogonal to the first main surface, the step of removing a part of the metal support includes removing the portion of the metal support located in the third region of the third main surface so that the metal support does not cover the third region and covers the fourth region. the whole

[0024] ​In the wiring circuit board manufactured by the above manufacturing method, a part of the wiring circuit board that overlaps with the first region of the first main surface and the third region of the third main surface when viewed in the crossing direction is called the first substrate portion. Also, another part of the wiring circuit board that overlaps with the second region of the first main surface and the fourth region of the third main surface when viewed in the crossing direction is called the second substrate portion.

[0025] In this case, the first substrate portion includes a part of the conductor layer, a part of the insulating layer, and a part of the metal thin film, and does not include the metal support. On the other hand, the second substrate portion includes the other part of the conductor layer, the other part of the insulating layer, the other part of the metal thin film, and the metal support.

[0026] As described above, the first substrate portion does not include the metal support. Thereby, in the first substrate portion, higher flexibility is ensured compared to the second substrate portion. On the other hand, the second substrate portion includes the metal support. Thereby, in the second substrate portion, a certain mechanical strength required to support the first substrate portion or to mount other members is ensured.

[0027] Also, in the above wiring circuit board, the metal thin film faces each of a part of the wiring formed in the first region of the first main surface and the other part of the wiring formed in the second region of the first main surface with the insulating layer interposed therebetween. Thereby, the impedance of a part of the conductor layer and the impedance of the other part of the conductor layer are adjusted by the common metal thin film. Therefore, the non-uniform adjustment of the impedance in a plurality of parts of the conductor layer is reduced.

[0028] As a result, a wiring circuit board having high flexibility and reduced impedance discontinuity is realized.

[0029] ( 9 ) The step of forming the metal thin film may include forming at least a part of the metal thin film by sputtering.

[0030] In this case, a thin metal film can be easily formed. Furthermore, the thickness of the sputtered film formed by sputtering can be made sufficiently small so as not to impair the flexibility of the wiring circuit board. Therefore, higher flexibility can be obtained in the first substrate portion.

[0031] ( 10 The step of forming a thin metal film may include forming at least a portion of the thin metal film by plating.

[0032] In this case, the thickness of the plating layer formed by the plating process can be adjusted relatively easily. Therefore, a metal thin film with a more appropriate thickness can be formed to reduce the impedance of the conductor layer. (11) A method for manufacturing a wiring circuit board according to yet another aspect of the present invention includes the steps of: preparing a metal support; forming a thin metal film made of a different metal material on the metal support; forming an insulating layer having a first main surface and a second main surface facing opposite directions on the thin metal film such that the second main surface is in contact with the thin metal film; forming a conductor layer on the first main surface of the insulating layer; and removing a part of the metal support after the step of forming the thin metal film, wherein the first main surface of the insulating layer is defined as having a first region, a second region and a third region which are different from each other, the first region and the second region which are adjacent, the second region and the third region which are adjacent, and the first region and the third region which are spaced apart, and the step of forming the conductor layer is to use at least a part of the conductor layer to form the first region, the second region and The step of removing a portion of the metal support includes forming wiring that extends through the third region in this order, wherein the metal thin film has a third main surface facing in the opposite direction to the insulating layer and in contact with the metal support, and where a fourth region, a fifth region, and a sixth region are defined on the third main surface of the metal thin film that overlap the first region, a second region, and a third region of the first main surface, respectively, when viewed in an intersecting direction perpendicular to the first main surface, the step of removing a portion of the metal support includes removing a portion of the metal support located in the fifth region of the third main surface such that the metal support does not cover the fifth region of the third main surface but covers the fourth region and the sixth region, and the step of removing a portion of the metal support further includes separating a portion of the metal support that covers the fourth region of the metal thin film from a portion of the metal support that covers the sixth region of the metal thin film. [Effects of the Invention]

[0033] According to the present invention, a wiring circuit board with high flexibility and reduced impedance discontinuities is realized. [Brief explanation of the drawing]

[0034] [Figure 1] This is a top view of a wiring circuit board according to one embodiment of the present invention. [Figure 2] Figure 1 is a bottom view of the wiring circuit board. [Figure 3] Figure 1 is a schematic cross-sectional view showing multiple sections of the wiring circuit board. [Figure 4] Figure 1 is a schematic cross-sectional view illustrating an example of a manufacturing method for a wiring circuit board. [Figure 5] Figure 1 is a schematic cross-sectional view illustrating an example of a manufacturing method for a wiring circuit board. [Figure 6] Figure 1 is a schematic cross-sectional view illustrating an example of a manufacturing method for a wiring circuit board. [Figure 7] This is a schematic cross-sectional view obtained by cutting multiple parts of a wiring circuit board equipped with a metal thin film according to the first modified example. [Figure 8] This is a schematic cross-sectional view obtained by cutting multiple parts of a wiring circuit board equipped with a metal thin film according to a second modified example. [Figure 9] This is a top view of a wiring circuit board according to another embodiment. [Figure 10] Figure 9 is a schematic cross-sectional view showing multiple sections of the wiring circuit board. [Figure 11] This is a top view of a wiring circuit board according to another embodiment. [Figure 12] Figure 11 is a schematic cross-sectional view showing multiple sections of the wiring circuit board. [Figure 13] Furthermore, this is a schematic cross-sectional view showing multiple parts of a wiring circuit board according to another embodiment. [Figure 14] This figure shows the measurement results of the impedance of the conductor layers of the wiring circuit boards of Comparative Examples 1 and 2 and Examples 1 to 3. [Modes for carrying out the invention]

[0035] Hereinafter, a wiring circuit board according to one embodiment of the present invention and a method for manufacturing the same will be described with reference to the drawings.

[0036] 1. Basic configuration of a wiring circuit board Figure 1 is a top view of a wiring circuit board according to one embodiment of the present invention. Figure 2 is a bottom view of the wiring circuit board 1 of Figure 1. Figure 3 is a schematic cross-sectional view of multiple parts of the wiring circuit board 1 of Figure 1. In Figure 3, the cross-sectional views along lines AA, BB, and CC of Figure 1 are shown in this order, from top to middle to bottom. Here, in order to make the configuration of the wiring circuit board 1 easier to understand, we define mutually orthogonal X, Y, and Z directions. In each figure from Figure 1 onward, the X, Y, and Z directions are indicated by arrows as appropriate. In this embodiment, the X and Y directions are mutually orthogonal in the horizontal plane, and the Z direction corresponds to the vertical direction.

[0037] As shown in Figures 1 and 2, the wiring circuit board 1 according to this embodiment has a rectangular shape extending in one direction (X direction) in a plan view. Furthermore, as shown in Figure 3, the wiring circuit board 1 has a configuration in which a metal support 10, a metal thin film 20, an insulating layer 30, and a conductor layer 40 are mainly stacked in this order in the Z direction.

[0038] The insulating layer 30 is formed of, for example, photosensitive polyimide. The thickness (length in the Z direction) of the insulating layer 30 is, for example, 1 μm or more and 30 μm or less. The insulating layer 30 may also be formed of other synthetic resins such as acrylic resin, polyethernitrile resin, polyethersulfone resin, epoxy resin, polyethylene terephthalate resin, polyethylene naphthalate resin, or polyvinyl chloride resin.

[0039] Furthermore, the insulating layer 30 has two main surfaces (upper and lower) facing in opposite directions. In the following description, one of the main surfaces (upper) of the insulating layer 30 will be referred to as the first main surface S1, and the other main surface (lower) of the insulating layer 30 will be referred to as the second main surface S2.

[0040] As shown by the dashed line in Figure 1, in the insulating layer 30 of this example, a rectangular first region A1 and two rectangular second regions A2 are set on the first main surface S1. The first region A1 is located in the central part of the wiring circuit board 1 in the longitudinal direction (X direction) of the wiring circuit board 1. The two second regions A2 are located at both ends of the wiring circuit board 1 and in their vicinity in the longitudinal direction (X direction) of the wiring circuit board 1. As a result, in the X direction, one second region A2 and the first region A1 are adjacent to each other, and the other second region A2 and the first region A1 are adjacent to each other.

[0041] Two conductor layers 40 are provided on the first main surface S1 of the insulating layer 30. Each conductor layer 40 is mainly made of copper and is formed on the first main surface S1 of the insulating layer 30 by electroplating. Each conductor layer 40 also has a wiring portion 41 and two terminal portions 42. The two terminal portions 42 are located in two second regions A2 near both ends of the wiring circuit board 1. Each terminal portion 42 is used to connect other electronic components to the conductor layer 40 of the wiring circuit board 1. The wiring portion 41 extends continuously, connecting the two terminal portions 42 through one second region A2, the first region A1, and the other second region A2. The thickness (length in the Z direction) of the conductor layer 40 is, for example, 0.25 μm or more and 50 μm or less. The width (length in the Y direction) of the wiring portion 41 of the conductor layer 40 is, for example, 0.25 μm or more and 300 μm or less.

[0042] A thin metal film 20 is provided on the second main surface S2 of the insulating layer 30, extending over the entire second main surface S2. The thin metal film 20 is formed from a metal or alloy containing one or more elements from, for example, copper, chromium, nickel, titanium, iron, molybdenum, and tungsten. In this example, the thin metal film 20 consists of a single layer made of copper or chromium. The thickness (length in the Z direction) of the thin metal film 20 is smaller than the thickness (length in the Z direction) of the metal support 10, which will be described later, and is preferably, for example, 20 nm or more and 5 μm or less, and preferably 20 nm or more and 3 μm or less.

[0043] The metal thin film 20, like the insulating layer 30, has two main surfaces (upper and lower) facing opposite directions. In the following description, the main surface of the metal thin film 20 facing opposite directions from the insulating layer 30 (the lower surface) will be referred to as the third main surface S3.

[0044] The third main surface S3 of the metal thin film 20 has a third region A3 and a fourth region A4, which correspond to the first region A1 and the second region A2 of the first main surface S1 of the insulating layer 30, respectively. Specifically, the third region A3 of the third main surface S3 is the region that overlaps with the first region A1 of the first main surface S1 in a plan view in the Z direction. The fourth region A4 of the third main surface S3 is the region that overlaps with the second region A2 of the first main surface S1 in a plan view in the Z direction.

[0045] A metal support 10 is provided on the third main surface S3 of the metal thin film 20 such that it does not cover the third region A3 but covers the fourth region A4. The metal support 10 is made of a different metal material than the metal thin film 20, and is formed of a metal or alloy containing one or more elements selected from the group consisting of copper, chromium, nickel, titanium, iron, molybdenum, and aluminum. Here, the difference between the metal material of the metal support 10 and the metal material of the metal thin film 20 means that at least one of the conductivity and relative permeability between the two metal materials is so different that they cannot be considered substantially identical. In this embodiment, the metal support 10 is made of stainless steel. The thickness (length in the Z direction) of the metal support 10 is, for example, 10 μm or more and 250 μm or less.

[0046] 2. Manufacturing method of the wiring circuit board 1 Figures 4 to 6 are schematic cross-sectional views illustrating an example of a manufacturing method for the wiring circuit board 1 shown in Figure 1. In each of Figures 4 to 6, as in the example in Figure 3, three cross-sectional views (corresponding cross-sectional views) corresponding to lines AA, BB, and CC in Figure 1 are shown in that order, at the top, middle, and bottom.

[0047] First, as shown in Figure 4, a thin metal film 20 is formed on the upper surface of the metal support 10. Film deposition techniques such as sputtering, electroplating, electroless plating, chemical vapor deposition, or physical vapor deposition are used to form the thin metal film 20. As described above, the thin metal film 20 in this example is made of copper or chromium. The lower surface of the thin metal film 20 that is in contact with the metal support 10 is the third main surface S3 described above.

[0048] Next, as shown in Figure 5, an insulating layer 30 made of photosensitive polyimide is formed on the upper surface of the metal thin film 20. The insulating layer 30 is formed by applying a photosensitive polyimide precursor to the entire upper surface of the metal thin film 20, and then exposing and developing the precursor. The formed insulating layer 30 is then subjected to a curing treatment by heating. The upper surface of the insulating layer 30 that is exposed upward is the first main surface S1 described above, and the lower surface of the insulating layer 30 that is in contact with the metal thin film 20 is the second main surface S2 described above. As described above, the first main surface S1 has a first region A1 and a second region A2, and the third main surface S3 has a third region A3 and a fourth region A4.

[0049] Next, as shown in Figure 6, one or more (two in this example) conductive layers 40 are formed on the first main surface S1 of the insulating layer 30. Specifically, the formation of the conductive layers 40 is carried out as follows.

[0050] First, a seed layer, for example, consisting of a chromium thin film and a copper thin film, is formed on the first main surface S1 of the insulating layer 30 by sputtering or electroless plating. Next, a plating resist with a predetermined pattern (the opposite pattern to the two conductive layers 40 in Figure 1) is formed on the seed layer. Then, a plating layer made of copper is formed on the seed layer exposed through the openings in the plating resist by electroplating.

[0051] Subsequently, the plating resist is peeled off, and the exposed seed layer (the portion where the plating layer is not formed) is removed by etching. This forms a conductive layer 40 consisting of a seed layer and a plating layer. In Figures 1, 6, and later Figures 8, 10, 12, and 13, the individual seed layer and plating layer constituting the conductive layer 40 are not shown.

[0052] Furthermore, a barrier layer may be formed on the outer surface of the exposed conductor layer 40 to suppress copper diffusion. For example, a nickel thin film can be used as the barrier layer. The nickel thin film can be formed, for example, by sputtering or electroless plating. In addition, a protective film may be formed on the first main surface S1 of the insulating layer 30 to protect the multiple wiring portions 41, such that it covers the multiple wiring portions 41 but does not cover the multiple terminal portions 42. For example, a photosensitive polyimide can be used as the material for the protective film. A protective film made of photosensitive polyimide can be formed in the same manner as the insulating layer 30.

[0053] Finally, the portion of the metal support 10 located on the third region A3 of the third main surface S3 is removed, for example, by wet etching. The etching solution used at this time is an etching solution that can dissolve the metal support 10 at a higher etching rate than the metal thin film 20. As a result, the third region A3 of the metal thin film 20 is exposed downwards, and the wiring circuit board 1 shown in Figures 1 to 3 is completed.

[0054] The above series of processes may be carried out using a roll-to-roll method. In this case, for example, a roll (hereinafter referred to as the feed roll) on which a long metal sheet made of stainless steel is wound is prepared. The metal sheet is fed out from the prepared feed roll. The metal sheet fed out from the feed roll is wound onto another roll. By performing the above series of processes on each part of the metal sheet as it moves from the feed roll to the other roll, it becomes possible to efficiently manufacture a large number of wiring circuit boards 1.

[0055] 3. Effects (1) In the above-described wiring circuit board 1, the portion of the wiring circuit board 1 that overlaps with the first region A1 of the first main surface S1 and the third region A3 of the third main surface S3 in a plan view in the Z direction is called the first substrate portion. In addition, the other portion of the wiring circuit board 1 that overlaps with the second region A2 of the first main surface S1 and the fourth region A4 of the third main surface S3 in a plan view in the Z direction is called the second substrate portion.

[0056] In this case, the first substrate portion includes a portion of the conductor layer 40, a portion of the insulating layer 30, and a portion of the metal thin film 20, but does not include the metal support 10. On the other hand, the second substrate portion includes the other portion of the conductor layer 40, the other portion of the insulating layer 30, the other portion of the metal thin film 20, and the metal support 10.

[0057] Thus, the first substrate portion does not include the metal support 10. As a result, the first substrate portion has higher flexibility compared to the second substrate portion. On the other hand, the second substrate portion includes the metal support 10. As a result, the second substrate portion has a certain level of mechanical strength necessary to support the first substrate portion on other components or to mount other components.

[0058] Furthermore, in the above-described wiring circuit board 1, a thin metal film 20 faces each of the wiring portion 41 formed in the first region A1 of the first main surface S1 and the other portion of the wiring portion 41 formed in the second region A2 of the first main surface S1, with an insulating layer 30 in between. As a result, the impedance of one part of the wiring portion 41 and the impedance of the other part of the wiring portion 41 are adjusted by the common thin metal film 20. Therefore, the uneven adjustment of impedance across multiple parts of the wiring portion 41 is reduced.

[0059] As a result, a wiring circuit board 1 is realized that has high flexibility and reduced impedance discontinuities.

[0060] (2) On the first main surface S1 of the insulating layer 30, the first region A1 is adjacent to each of the two second regions A2. As a result, the first substrate portion and the second substrate portion are aligned continuously in the longitudinal direction (X direction) of the wiring circuit board 1, so that the first substrate portion is properly supported by the second substrate portion.

[0061] (3) The thickness of the metal thin film 20 is less than the thickness of the metal support 10, and is between 20 nm and 5 μm. In this case, greater flexibility is ensured in the first substrate portion. In addition, the impedance of the wiring portion 41 of the conductor layer 40 formed in the first and second substrate portions is more appropriately adjusted.

[0062] 4. Modified form of the metal thin film 20 (1) First variation The metal thin film 20 provided on the wiring circuit board 1 may be composed of multiple layers. Figure 7 is a schematic cross-sectional view of multiple parts of the wiring circuit board 1 equipped with the metal thin film 20 according to the first modified example. In Figure 7, as in the example in Figure 3, three cross-sectional views corresponding to lines AA, BB, and CC in Figure 1 are shown in that order, from top to middle to bottom.

[0063] As shown in Figure 7, the metal thin film 20 according to the first modified example is composed of a first thin film layer 20a and a second thin film layer 20b. For the formation of the first thin film layer 20a and the second thin film layer 20b, film deposition techniques such as sputtering, electroplating, electroless plating, chemical vapor deposition, or physical vapor deposition are used.

[0064] The first thin film layer 20a and the second thin film layer 20b may be a chromium thin film and a copper thin film, respectively, formed by sputtering on the upper surface of the metal support 10. Alternatively, the first thin film layer 20a and the second thin film layer 20b may be a copper thin film and a chromium thin film, respectively, formed by sputtering on the upper surface of the metal support 10.

[0065] Alternatively, one of the first thin film layer 20a and the second thin film layer 20b may be formed by electroplating. For example, when manufacturing the wiring circuit board 1, in the process shown in Figure 4 above, a first thin film layer 20a made of copper may be formed on the upper surface of the metal support 10 by electroplating. Furthermore, a second thin film layer 20b made of a chromium thin film may be formed on the first thin film layer 20a so as to cover the first thin film layer 20a.

[0066] As will be described later, the degree of impedance reduction in the wiring section 41 varies depending on the thickness of the metal thin film 20. With electroplating, the thickness of the formed plating layer can be adjusted relatively easily by appropriately adjusting processing conditions such as processing time. Therefore, as described above, when one of the first thin film layer 20a and the second thin film layer 20b is formed by electroplating, it becomes possible to form a metal thin film 20 with a more appropriate thickness to reduce the impedance of the wiring section 41.

[0067] Furthermore, as described above, when the upper surface of the metal thin film 20 is composed of a second thin film layer 20b made of a chromium thin film, the adhesion between the first thin film layer 20a and the insulating layer 30 is improved by further forming an insulating layer 30 on the second thin film layer 20b. Note that when the first thin film layer 20a is composed of a copper thin film, the second thin film layer 20b may be any of the nickel thin film, titanium thin film, molybdenum thin film, or tungsten thin film formed by sputtering, instead of a chromium thin film. In this case as well, the adhesion between the first thin film layer 20a and the insulating layer 30 is improved.

[0068] (2) Second variation Figure 8 is a schematic cross-sectional view of multiple parts of a wiring circuit board 1 equipped with a metal thin film 20 according to a second modified example. In Figure 8, as in the example in Figure 3, three cross-sectional views corresponding to lines AA, BB, and CC in Figure 1 are shown in that order, from top to middle to bottom.

[0069] As shown in Figure 8, the metal thin film 20 according to the second modified example is composed of a first thin film layer 20a, a second thin film layer 20b, and a third thin film layer 20c. For the formation of each of the first thin film layer 20a, the second thin film layer 20b, and the third thin film layer 20c, a film deposition technique such as sputtering, electroplating, electroless plating, chemical vapor deposition, or physical vapor deposition is used. Each of the first thin film layer 20a, the second thin film layer 20b, and the third thin film layer 20c is composed of a metal thin film such as a copper thin film, a chromium thin film, a nickel thin film, a titanium thin film, a molybdenum thin film, or a tungsten thin film.

[0070] The first thin film layer 20a and the second thin film layer 20b may be a chromium thin film and a copper thin film, respectively, formed by sputtering on the upper surface of the metal support 10. In this case, the third thin film layer 20c may be a copper plating layer formed by electroplating on the copper thin film of the second thin film layer 20b.

[0071] Alternatively, the first thin film layer 20a may be a copper plating layer formed by electroplating on the upper surface of the metal support 10. In this case, the second thin film layer 20b and the third thin film layer 20c may be a copper thin film and a chromium thin film, respectively, formed by sputtering on the plating layer of the first thin film layer 20a.

[0072] Alternatively, the first thin film layer 20a may be a copper thin film formed by sputtering on the upper surface of the metal support 10. In this case, the second thin film layer 20b may be a copper plating layer formed by electroplating on the upper surface of the metal support 10. Furthermore, the third thin film layer 20c may be a chromium thin film formed by sputtering on the plating layer of the second thin film layer 20b.

[0073] 5. Other Embodiments (1) In the first main surface S1 of the insulating layer 30 according to the above embodiment, one of the two second regions A2, the first region A1, and the other of the two second regions A2 are arranged in this order in the X direction. However, the present invention is not limited to the above example. The first region A1 and the second region A2 on the first main surface S1 of the insulating layer 30 may be set as follows.

[0074] Figure 9 is a top view of a wiring circuit board 1 according to another embodiment. Figure 10 is a schematic cross-sectional view of multiple parts of the wiring circuit board 1 of Figure 9. In Figure 10, the cross-sectional views along lines AA, BB, and CC of Figure 9 are shown in that order, from top, middle, and bottom. The differences between the wiring circuit board 1 of Figures 9 and 10 and the wiring circuit board 1 of Figure 1 will be explained below.

[0075] In the wiring circuit board 1 shown in Figure 9, one first region A1 and one second region A2 are set on the first main surface S1 of the insulating layer 30. The first region A1 is set up as an island in the central part in the longitudinal direction (X direction) and the short direction (Y direction) of the wiring circuit board 1. On the other hand, the second region A2 is set up to surround the first region A1. Similar to the wiring circuit board 1 shown in Figure 1, most of the wiring portions 41 of the two conductor layers 40 are located on the first region A1. The remaining portions of the wiring portions 41 of the two conductor layers 40 and the terminal portions 42 of the two conductor layers 40 are located on the second region A2.

[0076] As described above, a first region A1 and a second region A2 are set on the first main surface S1. As a result, in the wiring circuit board 1 of this example, a third region A3 (not shown) is set on the third main surface S3 of the metal thin film 20, which overlaps with the first region A1 of the first main surface S1 in a plan view in the Z direction. In addition, a fourth region A4 (not shown) is set, which overlaps with the second region A2 of the first main surface S1 in a plan view in the Z direction.

[0077] As a result, as shown in Figure 10, in the wiring circuit board 1 of this example, at least a portion of the metal support 10 is located on the third main surface S3 of the metal thin film 20 throughout the X direction. Specifically, in the wiring circuit board 1 of this example, as shown in the central part of Figure 10, a line-shaped metal support 10 is provided near the wiring portion 41 of each conductor layer 40, extending parallel to the wiring portion 41. This makes it possible to obtain the necessary mechanical strength in the region near the wiring portion 41.

[0078] In this way, by appropriately providing metal supports 10 to multiple parts of the wiring circuit board 1, it becomes possible to provide each of the multiple parts of the wiring circuit board 1 with the desired flexibility and the desired mechanical strength.

[0079] (2) The wiring circuit board 1 according to the above embodiment has a rectangular shape extending in one direction (X direction) when viewed from above, but the present invention is not limited thereto. The wiring circuit board 1 may have the following shapes.

[0080] Figure 11 is a top view of a wiring circuit board 1 according to yet another embodiment. Figure 12 is a schematic cross-sectional view of multiple parts of the wiring circuit board 1 of Figure 11. In Figure 12, the cross-sectional views along lines AA, BB, and CC of Figure 11 are shown in that order, from top, middle, and bottom. The differences between the wiring circuit board 1 of Figures 11 and 12 and the wiring circuit board 1 of Figure 1 will be explained below.

[0081] As shown in Figures 11 and 12, the wiring circuit board 1 in this example is formed such that the width (length in the Y direction) of the insulating layer 30 changes in stages in the direction in which the wiring portions 41 of the two conductor layers 40 extend. Specifically, the insulating layer 30 is formed to be larger at both ends and their vicinity in the longitudinal direction (X direction) of the wiring circuit board 1, and smaller in other parts. As a result, the width (length in the Y direction) of the first region A1 set on the first main surface S1 is smaller than the width (length in the Y direction) of the second region A2. With this configuration, it is possible to obtain greater flexibility in the portion of the wiring circuit board 1 located between the two second regions A2.

[0082] (3) In the wiring circuit board 1 according to the above embodiment, a thin metal film 20 is formed on the upper surface of the metal support 10, but the present invention is not limited thereto. A new insulating layer 31 may be formed between the metal support 10 and the thin metal film 20.

[0083] Figure 13 is a schematic cross-sectional view of multiple parts of a wiring circuit board 1 according to yet another embodiment. The top view of the wiring circuit board 1 in this example is the same as the top view of the wiring circuit board 1 in Figure 1. In Figure 13, as in the example in Figure 3, three cross-sectional views corresponding to lines AA, BB, and CC in Figure 1 are shown in that order, from top to middle to bottom.

[0084] In the wiring circuit board 1 of Figure 13, a new insulating layer 31, different from the insulating layer 30, is further formed on the upper surface of the metal support 10. In this case as well, since the metal thin film 20 is formed to face the entire conductor layer 40 with the insulating layer 30 in between, the same effects as in the above embodiment can be obtained.

[0085] (4) When manufacturing the wiring circuit board 1, the insulating layer 30 may be formed using a photosensitive carrier film. Specifically, the insulating layer 30 may be formed by attaching an insulating film made of photosensitive polyimide to the upper surface of the metal thin film 20.

[0086] (5) In the wiring circuit board 1 according to the above embodiment, the metal thin film 20 is formed so as to overlap the entire insulating layer 30 in a plan view, but it is sufficient if the metal thin film 20 overlaps the entire conductive layer 40.

[0087] For example, on the first main surface S1 of the wiring circuit board 1 according to the above embodiment, the first region A1 and the second region A2 may be set to be spaced apart from each other in the X direction, with another new region in between. Here, if the wiring portion 41 of the conductor layer 40 is located on the other new region, the metal thin film 20 is formed so that, in a plan view in the Z direction, it overlaps the first region A1 and the second region A2 and also overlaps the other new region. On the other hand, if the wiring portion 41 of the conductor layer 40 is not located on the other new region, the metal thin film 20 may be formed so that, in a plan view in the Z direction, it overlaps the first region A1 and the second region A2 but does not overlap the other new region.

[0088] 5. Correspondence between each component of the claim and each part of the embodiment The following describes examples of the correspondence between each component of the claims and each element of the embodiments, but the present invention is not limited to the following examples. Various other elements having the configuration or function described in the claims can also be used as each component of the claims.

[0089] In the above embodiment, the wiring circuit board 1 is an example of a wiring circuit board, the first main surface S1 is an example of a first main surface, the second main surface S2 is an example of a second main surface, the insulating layer 30 is an example of an insulating layer, the conductor layer 40 is an example of a conductor layer, the third main surface S3 is an example of a third main surface, and the metal thin film 20 is an example of a metal thin film.

[0090] Also, With regard to some claims, The first region A1 is an example of the first region, the second region A2 is an example of the second region, the wiring portion 41 is an example of wiring, the third region A3 is an example of the third region, the fourth region A4 is an example of the fourth region, the first thin film layer 20a is an example of the first metal film, and the second thin film layer 20b is an example of the second metal film. Furthermore, with respect to other claims, the first region A1 is an example of the second region, two spaced-apart second regions A2 are examples of the first and third regions, the wiring section 41 is an example of wiring, the third region A3 is an example of the fifth region, and two spaced-apart fourth regions A4 are examples of the fourth and sixth regions.

[0091] 6. Test on the impedance reduction effect of the metal thin film 20 on the wiring section 41. The inventors fabricated wiring circuit boards of Comparative Examples 1 and 2 and Examples 1 to 3 in order to confirm the degree of impedance reduction of the wiring section 41 corresponding to multiple types of metal thin films 20.

[0092] Specifically, the inventors fabricated a wiring circuit board having the same configuration as the wiring circuit board 1 shown in Figures 1 to 3, except that it does not have a metal support 10 and a metal thin film 20, as the wiring circuit board for Comparative Example 1.

[0093] Furthermore, the inventors fabricated a wiring circuit board having the same configuration as the wiring circuit board 1 shown in Figures 1 to 3, except that it does not have a thin metal film 20 and the metal support 10 is provided so as to the entire second main surface S2 of the insulating layer 30, as the wiring circuit board of Comparative Example 2. In the wiring circuit board of Comparative Example 2, the thickness (length in the Z direction) of the metal support 10 was 18 μm.

[0094] Furthermore, the inventors fabricated a wiring circuit board having the same configuration as the wiring circuit board 1 shown in Figures 1 to 3, but with the metal thin film 20 formed as a single layer of chromium, as the wiring circuit board of Example 1. The chromium metal thin film 20 was formed by sputtering. In the wiring circuit board of Example 1, the thickness (length in the Z direction) of the metal thin film 20 was 50 nm.

[0095] Furthermore, the inventors fabricated a wiring circuit board having the same configuration as the wiring circuit board 1 shown in Figures 1 to 3, but with the metal thin film 20 formed as a single layer of copper, as the wiring circuit board of Example 2. The copper metal thin film 20 was formed by sputtering. In the wiring circuit board of Example 2, the thickness (length in the Z direction) of the metal thin film 20 was 50 nm.

[0096] Furthermore, the inventors fabricated a wiring circuit board having the same configuration as the wiring circuit board 1 in Figure 7 as the wiring circuit board of Example 3. The first thin film layer 20a was made of chromium and formed by sputtering. The second thin film layer 20b was made of copper and formed by sputtering. In the wiring circuit board of Example 3, the thickness (length in the Z direction) of the first thin film layer 20a was 50 nm, and the thickness (length in the Z direction) of the second thin film layer 20b was 50 nm. Therefore, the thickness (length in the Z direction) of the metal thin film 20 was 100 nm.

[0097] Furthermore, the dimensions of each part of the two wiring sections 41, such as length, width, spacing, and thickness, are equal between the wiring circuit boards of Comparative Examples 1 and 2 and Examples 1 to 3. Also, the thickness of the insulating layer 30 is equal between the wiring circuit boards of Comparative Examples 1 and 2 and Examples 1 to 3.

[0098] The impedance of the conductor layer 40 was measured using the TDR (Time Domain Reflectometry) method for several wiring circuit boards fabricated as described above. Figure 14 shows the measurement results of the impedance of the conductor layer 40 of the wiring circuit boards of Comparative Examples 1 and 2 and Examples 1 to 3.

[0099] Figure 14 shows the impedance measurement results in a graph. In this graph, the vertical axis represents impedance, and the horizontal axis represents time. In the graph of Figure 14, the impedance measurement results corresponding to the conductor layer 40 of Comparative Example 1 are shown by a dotted line, and the impedance measurement results corresponding to the conductor layer 40 of Comparative Example 2 are shown by a solid line. Furthermore, the impedance measurement results corresponding to the conductor layer 40 of Example 1 are shown by a thick solid line, the impedance measurement results corresponding to the conductor layer 40 of Example 2 are shown by a thick dotted line, and the impedance measurement results corresponding to the conductor layer 40 of Example 3 are shown by a thick dashed line. Note that in the graph of Figure 14, the impedance shown within the range of approximately 200 ps to approximately 400 ps on the horizontal axis (time axis) represents the impedance corresponding to the wiring section 41 of each wiring circuit board.

[0100] According to the graph in Figure 14, the impedance of the wiring section 41 in Comparative Example 1 is higher than the impedance of the wiring section 41 in Comparative Example 2 and Examples 1-3. In contrast, the impedance of the wiring section 41 in Comparative Example 2 is significantly lower than the impedance of the wiring section 41 in Comparative Example 1 and Examples 1-3.

[0101] The impedance of the wiring section 41 in Examples 1 and 2 is almost the same, sufficiently lower than the impedance of the wiring section 41 in Comparative Example 1, and slightly higher than the impedance of the wiring section 41 in Comparative Example 2 and Example 3. The impedance of the wiring section 41 in Example 3 is sufficiently lower than the impedance of the wiring section 41 in Comparative Example 1, and is located between the impedance of the wiring section 41 in Comparative Example 2 and the impedance of the wiring section 41 in Examples 1 and 2.

[0102] In the wiring circuit board of Comparative Example 2, the portion of the metal support 10 that overlaps each wiring portion 41 in a plan view in the Z direction functions as an impedance reduction layer that reduces the impedance of the wiring portion 41. On the other hand, in each of the wiring circuit boards of Examples 1 to 3, the portion of the metal thin film 20 that overlaps each wiring portion 41 in a plan view functions as an impedance reduction layer that reduces the impedance of the wiring portion 41.

[0103] In Comparative Example 2, the thickness of the metal support 10, which functions as an impedance reduction layer, is greater than the thickness of the metal thin film 20, which functions as an impedance reduction layer, in the wiring circuit boards of Examples 1 to 3. Furthermore, the thickness of the metal thin film 20, which functions as an impedance reduction layer, in the wiring circuit board of Example 3 is greater than the thickness of the metal thin film 20, which functions as an impedance reduction layer, in the wiring circuit boards of Examples 1 and 2. Considering these points, it was found that the degree of impedance reduction in the wiring portion 41 is greater when the thickness of the impedance reduction layer is greater, and less when the thickness of the impedance reduction layer is smaller. Therefore, when manufacturing the wiring circuit board 1 according to the present invention, it is preferable to adjust the thickness of the metal thin film 20 that overlaps the wiring portion 41 in a plan view according to the required degree of impedance reduction. 7. Reference form (1) A wiring circuit board according to one aspect of this reference embodiment comprises an insulating layer having a first main surface and a second main surface facing opposite directions, a conductor layer provided on the first main surface of the insulating layer, a metal thin film provided on the second main surface of the insulating layer and having a third main surface facing opposite directions to the insulating layer, and a metal support made of a metal material different from at least a portion of the metal material of the metal thin film, wherein the first main surface of the insulating layer has a first region and a second region which are different from each other, at least a portion of the conductor layer constitutes wiring that extends through the first region and the second region of the first main surface, and in the case where the third main surface of the metal thin film defines a third region and a fourth region which overlap the first region and the second region of the first main surface when viewed in a cross direction perpendicular to the first main surface, the metal support is provided on the third main surface such that it does not cover the third region of the third main surface but covers the fourth region. In this wiring circuit board, the portion of the wiring circuit board that overlaps with the first region of the first main surface and the third region of the third main surface when viewed in the intersecting direction is called the first substrate portion. The other portion of the wiring circuit board that overlaps with the second region of the first main surface and the fourth region of the third main surface when viewed in the intersecting direction is called the second substrate portion. In this case, the first substrate portion includes a portion of the conductor layer, a portion of the insulating layer, and a portion of the metal thin film, but does not include a metal support. On the other hand, the second substrate portion includes the other portion of the conductor layer, the other portion of the insulating layer, the other portion of the metal thin film, and a metal support. As described above, the first substrate portion does not include a metal support. As a result, the first substrate portion has higher flexibility compared to the second substrate portion. On the other hand, the second substrate portion includes a metal support. As a result, the second substrate portion has a certain level of mechanical strength necessary to support the first substrate portion on other components or to mount other components. Furthermore, in the above-described wiring circuit board, a thin metal film is positioned opposite each of the wiring formed in the first region of the first main surface and the wiring formed in the second region of the first main surface, with an insulating layer in between. As a result, the impedance of one part of the conductor layer and the impedance of the other part of the conductor layer are adjusted by the common thin metal film. Therefore, the uneven adjustment of impedance across multiple parts of the conductor layer is reduced. As a result, a wiring circuit board with high flexibility and reduced impedance discontinuities is realized. (2) On the first main surface, the first region and the second region may be adjacent to each other. In this case, the first substrate portion and the second substrate portion are arranged in a continuous line, so that the first substrate portion is properly supported by the second substrate portion. (3) The metal thin film includes a first metal film and a second metal film stacked in intersecting directions, and at least one of the metal materials of the first metal film and the second metal film may be different from the metal material of the metal support. In this case, a first metal film and a second metal film are used as the metal thin film. Therefore, by appropriately determining the metal materials used for the first and second metal films, a more suitable metal thin film can be formed to reduce the impedance of the conductor layer. Alternatively, a more suitable metal thin film can be formed to improve the adhesion between the metal thin film and the metal support to the insulating layer. (4) The metal thin film may include a plating layer. The degree of reduction in the impedance of the conductor layer varies depending on the thickness of the metal thin film. According to the above configuration, at least a portion of the metal thin film includes a plating layer. When forming a plating layer, the thickness of the formed plating layer can be adjusted relatively easily by appropriately adjusting the plating processing conditions such as processing time. Therefore, it becomes possible to form a metal thin film with a more appropriate thickness for reducing the impedance of the conductor layer. (5) The thickness of the metal thin film may be less than the thickness of the metal support. In this case, greater flexibility is ensured in the first substrate portion. (6) The thickness of the metal thin film may be 20 nm or more and 5 μm or less. In this case, the impedance of the conductor layers formed on the first substrate and the second substrate is more appropriately adjusted. (7) A method for manufacturing a wiring circuit board according to other aspects of this reference embodiment includes the steps of: preparing a metal support; forming a thin metal film made of a metal material different from the metal support on the metal support; forming an insulating layer having a first main surface and a second main surface facing opposite directions on the thin metal film such that the second main surface is in contact with the thin metal film; forming a conductor layer on the first main surface of the insulating layer; and removing a part of the metal support after the step of forming the thin metal film, wherein the first main surface of the insulating layer has a first region and a second region that are different from each other, and the step of forming the conductor layer is the step of forming the conductor layer The step of removing a portion of the metal support includes, at least in part, forming wiring that extends through a first region and a second region of a first main surface, wherein the metal thin film has a third main surface that faces in the opposite direction to the insulating layer and is in contact with a metal support, and the third main surface of the metal thin film defines a third region and a fourth region that overlap the first region and the second region of the first main surface, respectively, when viewed in an intersecting direction perpendicular to the first main surface, the step of removing a portion of the metal support includes removing a portion of the metal support located in the third region of the third main surface such that the metal support does not cover the third region of the third main surface but covers the fourth region. In a wiring circuit board manufactured by the above manufacturing method, a portion of the wiring circuit board that overlaps with the first region of the first main surface and the third region of the third main surface when viewed in the intersecting direction is called the first substrate portion. The other portion of the wiring circuit board that overlaps with the second region of the first main surface and the fourth region of the third main surface when viewed in the intersecting direction is called the second substrate portion. In this case, the first substrate portion includes a portion of the conductor layer, a portion of the insulating layer, and a portion of the metal thin film, but does not include a metal support. On the other hand, the second substrate portion includes the other portion of the conductor layer, the other portion of the insulating layer, the other portion of the metal thin film, and a metal support. As described above, the first substrate portion does not include a metal support. As a result, the first substrate portion has higher flexibility compared to the second substrate portion. On the other hand, the second substrate portion includes a metal support. As a result, the second substrate portion has a certain level of mechanical strength necessary to support the first substrate portion on other components or to mount other components. Furthermore, in the above-described wiring circuit board, a thin metal film is positioned opposite each of the wiring formed in the first region of the first main surface and the wiring formed in the second region of the first main surface, with an insulating layer in between. As a result, the impedance of one part of the conductor layer and the impedance of the other part of the conductor layer are adjusted by the common thin metal film. Therefore, the uneven adjustment of impedance across multiple parts of the conductor layer is reduced. As a result, a wiring circuit board with high flexibility and reduced impedance discontinuities is realized. (8) The step of forming a metal thin film may include forming at least a portion of the metal thin film by sputtering. In this case, a thin metal film can be easily formed. Furthermore, the thickness of the sputtered film formed by sputtering can be made sufficiently small so as not to impair the flexibility of the wiring circuit board. Therefore, higher flexibility can be obtained in the first substrate portion. (9) The step of forming a metal thin film may include forming at least a portion of the metal thin film by plating. In this case, the thickness of the plating layer formed by the plating process can be adjusted relatively easily. Therefore, a metal thin film with a more appropriate thickness can be formed to reduce the impedance of the conductor layer. [Explanation of Symbols]

[0104] 1…Wiring circuit board, 10…Metal support, 20…Metal thin film, 20a…First thin film layer, 20b…Second thin film layer, 20c…Third thin film layer, 30…Insulating layer, 31…Insulating layer, 40…Conducting layer, 41…Wiring section, 42…Terminal section, A1…First region, A2…Second region, A3…Third region, A4…Fourth region, S1…First main surface, S2…Second main surface, S3…Third main surface

Claims

1. An insulating layer having a first main surface and a second main surface facing opposite directions, A conductive layer provided on the first main surface of the insulating layer, A thin metal film is provided on the second main surface of the insulating layer so as to cover the entire second main surface of the insulating layer, and having a third main surface facing in the opposite direction to the insulating layer. The metal thin film comprises a metal support made of a metal material different from at least a portion of the metal material, The first main surface of the insulating layer has two distinct regions: a first region and a second region. At least a portion of the conductor layer constitutes wiring that extends through the first region and the second region of the first main surface, In the third main surface of the metal thin film, when a third region and a fourth region are defined that overlap the first region and the second region of the first main surface, respectively, when viewed in a direction perpendicular to the first main surface, the metal support is provided on the third main surface such that it does not cover the third region but covers the fourth region, and this is a wiring circuit board.

2. The wiring circuit board according to claim 1, wherein the first region and the second region are adjacent to each other on the first main surface.

3. The metal thin film includes a first metal film and a second metal film stacked in the intersecting direction, The wiring circuit board according to claim 1 or 2, wherein at least one of the first metal film and the second metal film is different from the metal material of the metal support.

4. The wiring circuit board according to claim 1 or 2, wherein the metal thin film includes a plating layer.

5. The wiring circuit board according to claim 1 or 2, wherein the thickness of the metal thin film is smaller than the thickness of the metal support.

6. The wiring circuit board according to claim 1 or 2, wherein the thickness of the metal thin film is 20 nm or more and 5 μm or less.

7. An insulating layer having a first main surface and a second main surface facing opposite directions, A conductive layer provided on the first main surface of the insulating layer, A metal thin film provided on the second main surface of the insulating layer and having a third main surface facing in the opposite direction to the insulating layer, The metal thin film comprises a metal support made of a metal material different from at least a portion of the metal material, The first main surface of the insulating layer is defined with respect to a first region, a second region, and a third region, which are all different from each other. The first region and the second region are adjacent to each other. The second region and the third region are adjacent to each other. The first region and the third region are separated, At least a portion of the conductor layer constitutes wiring that extends through the first region, the second region, and the third region of the first main surface in that order. In the third main surface of the metal thin film, when a fourth region, a fifth region, and a sixth region are defined that overlap the first region, the second region, and the third region of the first main surface, respectively, when viewed in a direction perpendicular to the first main surface, the metal support is provided on the third main surface such that it does not cover the fifth region of the third main surface, but covers the fourth region and the sixth region. A wiring circuit board in which the portion of the metal support covering the fourth region of the metal thin film and the portion of the metal support covering the sixth region of the metal thin film are spaced apart from each other.

8. The steps include preparing a metal support and The steps of forming a thin metal film made of a different metal material than the metal support on the metal support, The steps include forming an insulating layer having a first main surface and a second main surface facing opposite directions on the metal thin film such that the entire second main surface is in contact with the metal thin film, The steps include forming a conductive layer on the first main surface of the insulating layer, The step of forming the metal thin film includes the step of removing a portion of the metal support, The first main surface of the insulating layer has two distinct regions: a first region and a second region. The step of forming the conductor layer includes forming wiring on at least a portion of the conductor layer that extends through the first region and the second region of the first main surface, The metal thin film has a third main surface that faces in the opposite direction to the insulating layer and is in contact with the metal support. A method for manufacturing a wiring circuit board, wherein, in the third main surface of the metal thin film, a third region and a fourth region are defined that overlap the first region and the second region of the first main surface, respectively, when viewed in an intersecting direction perpendicular to the first main surface, the step of removing a part of the metal support includes removing the portion of the metal support located in the third region of the third main surface such that the metal support does not cover the third region of the third main surface but covers the fourth region.

9. The step of forming the metal thin film is, A method for manufacturing a wiring circuit board according to claim 8, comprising forming at least a portion of the metal thin film by sputtering.

10. The step of forming the metal thin film is, A method for manufacturing a wiring circuit board according to claim 8 or 9, comprising forming at least a portion of the metal thin film by plating.

11. The steps of preparing a metal support, The steps of forming a thin metal film made of a different metal material than the metal support on the metal support, The steps include forming an insulating layer having a first main surface and a second main surface facing opposite directions on the metal thin film such that the second main surface is in contact with the metal thin film, The steps include forming a conductive layer on the first main surface of the insulating layer, The step of forming the metal thin film includes the step of removing a portion of the metal support, The first main surface of the insulating layer is defined with respect to a first region, a second region, and a third region, which are all different from each other. The first region and the second region are adjacent to each other. The second region and the third region are adjacent to each other. The first region and the third region are separated, The step of forming the conductor layer includes forming wiring on at least a portion of the conductor layer that extends through the first region, the second region, and the third region of the first main surface in that order, The metal thin film has a third main surface that faces in the opposite direction to the insulating layer and is in contact with the metal support. In the third main surface of the metal thin film, if a fourth region, a fifth region, and a sixth region are defined that overlap the first region, the second region, and the third region of the first main surface, respectively, when viewed in an intersecting direction perpendicular to the first main surface, the step of removing a portion of the metal support includes removing the portion of the metal support located in the fifth region of the third main surface such that the metal support does not cover the fifth region of the third main surface, but covers the fourth region and the sixth region. A method for manufacturing a wiring circuit board, wherein the step of removing a portion of the metal support further includes separating the portion of the metal support that covers the fourth region of the metal thin film from the portion of the metal support that covers the sixth region of the metal thin film.

Images