Printed circuit board and method for manufacturing same

Abstract

The insulating layer has a first main surface and a second main surface. The conductor layer is arranged on the first main surface. The metal thin film is provided on the second main surface and has a third main surface facing a direction opposite to the insulating layer. The metal support includes a metal material different from the metal thin film. A first region and a second region are defined on the first main surface, and the conductor layer constitutes a wiring extending so as to pass through the first region and the second region in the first main surface. When a third region and a fourth region that overlap the first region and the second region of the first main surface in plan view are defined in the third main surface, the metal support body is provided on the third main surface so as not to cover the third region and cover the fourth region.

Description

Technical Field

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

[0002] As an example of the wired circuit board, there is a suspension board with circuit in which an insulating layer is formed on a metal supporting board, and a conductive layer as wiring is formed on the insulating layer.

[0003] Prior art literature Patent Literature Patent Document 1: Japanese Patent Application Publication No. 2012-243382 Summary of the invention

[0004] Problems to be solved by the invention In recent years, the use of wiring circuit substrates has been expanding. Depending on the use of the wiring circuit substrate, there is a case where the wiring circuit substrate is required to have higher flexibility. In the above-mentioned suspension substrate with circuit, the metal support substrate has a relatively high rigidity compared with the insulating layer and the conductor layer. Therefore, it is generally believed that a wiring circuit substrate with high flexibility can be realized by removing a part of the metal support substrate from the above-mentioned basic structure of the suspension substrate with circuit.

[0005] In the portion where the conductor layer and the metal supporting substrate face each other via the insulating layer in the suspension substrate with circuit, the metal supporting substrate reduces the impedance of the conductor layer (wiring). Therefore, if a portion of the metal supporting substrate is removed, the impedance of the conductor layer cannot be reduced. In this case, since the impedance of the conductor layer (wiring) deviates from a desired value, there is a possibility that impedance mismatching occurs between the conductor layer and the electronic component connected to the conductor layer.

[0006] Patent Document 1 describes an example of a suspension flexible substrate (wiring circuit substrate) in which an insulating layer and wiring are sequentially stacked on a stainless steel metal support substrate having an opening region. In the following description, with respect to the suspension flexible substrate of Patent Document 1, the direction in which the metal support substrate, the insulating layer, and the wiring are stacked is referred to as a substrate stacking direction.

[0007] In the suspension flexible substrate, the opening region of the metal supporting substrate overlaps with a portion of the wiring in the substrate stacking direction. In addition, in the suspension flexible substrate, in order to reduce the impedance of the wiring, a conductor film having a higher conductivity than the metal supporting substrate is formed in the opening region of the metal supporting substrate. The conductor film overlaps with a portion of the wiring in the substrate stacking direction.

[0008] According to this structure, multiple portions of the wiring overlap with the metal supporting substrate or the conductor film in the substrate stacking direction. As a result, the impedance of the wiring is reduced. However, in the suspension flexible substrate of Patent Document 1, the metal supporting substrate and the conductor film are made of materials having at least different electrical conductivity (conductivity).

[0009] Regarding the above-mentioned multiple portions of the wiring, the degree to which the impedance can be reduced varies depending on the conductivity of the members (in the above-mentioned example, the conductor film and the metal supporting substrate) that are respectively opposed to the multiple portions of the wiring through the insulating layer in the substrate stacking direction. Therefore, there is a difference in the degree to which the impedance can be reduced between a portion of the wiring overlapping the conductor film in the substrate stacking direction and the other portion of the wiring overlapping the metal supporting substrate in the substrate stacking direction. The discontinuity of the impedance in the wiring reduces the electrical characteristics of the wiring.

[0010] An object of the present invention is to provide a printed circuit board having high flexibility and reduced impedance discontinuity, and a method for manufacturing the same.

[0011] Technical solutions to solve problems (1) According to one aspect of the present invention, a wiring circuit substrate comprises: an insulating layer having a first main surface and a second main surface facing opposite directions to each other; a conductor layer provided on the first main surface of the insulating layer; a metal 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; and a metal support body comprising a metal material different from the metal material of at least a portion of the metal film, wherein on the first main surface of the insulating layer, first and second regions different from each other are defined, at least a portion of the conductor layer constitutes wiring extending in a manner passing through the first and second regions in the first main surface, and when a third region and a fourth region are defined in the third main surface of the metal film, the third region and the fourth region respectively overlapping with the first and second regions of the first main surface when viewed in a cross direction orthogonal to the first main surface, the metal support body is provided on the third main surface in a manner not covering the third region in the third main surface but covering the fourth region in the third main surface.

[0012] In the wiring circuit substrate, a portion of the wiring circuit substrate that overlaps the first region of the first main surface and the third region of the third main surface when viewed in the cross direction is referred to as a first substrate portion. In addition, the other portion of the wiring circuit substrate that overlaps the second region of the first main surface and the fourth region of the third main surface when viewed in the cross direction is referred to as a 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 film, but does not include a metal support. On the other hand, the second substrate portion includes the rest of the conductor layer, the rest of the insulating layer, the rest of the metal film, and the metal support.

[0014] As described above, the first substrate portion does not include a metal support body. Thus, in the first substrate portion, a higher flexibility than that of the second substrate portion can be ensured. On the other hand, the second substrate portion includes a metal support body. Thus, in the second substrate portion, a certain mechanical strength required for supporting the first substrate portion on other components or for mounting other components can be ensured.

[0015] In addition, in the above-mentioned wiring circuit substrate, the metal film is opposed to a part of the wiring formed in the first area of ​​the first main surface and the other part of the wiring formed in the second area of ​​the first main surface respectively through the insulating layer. Thus, the impedance of a part of the conductor layer and the impedance of the other part of the conductor layer are adjusted by using the common metal film. Therefore, it is possible to reduce the situation where the impedance is adjusted unevenly in multiple parts of the conductor layer.

[0016] As a result, a printed circuit board having high flexibility and reduced impedance discontinuity can be realized.

[0017] (2) The first region and the second region may be adjacent to each other on the first main surface. In this case, the first substrate portion and the second substrate portion are continuously arranged, so the first substrate portion is appropriately supported by the second substrate portion.

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

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

[0020] (4) The metal 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 film. According to the above structure, at least a portion of the metal film includes a plating layer. When forming the plating layer, the thickness of the formed plating layer can be adjusted relatively easily by appropriately adjusting the plating processing conditions such as the processing time. Therefore, a metal film having a more appropriate thickness can be formed in order to reduce 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 body. In this case, higher flexibility can be ensured in the first substrate portion.

[0022] (6) The thickness of the metal thin film may be greater than or equal to 20 nm and less than or equal to 5 μm. In this case, the impedance of the conductor layer formed on the first substrate portion and the second substrate portion can be adjusted more appropriately.

[0023] (7) According to another aspect of the present invention, a method for manufacturing a wiring circuit substrate comprises: a step of preparing a metal support; a step of forming a metal film including a metal material different from that of the metal support on the metal support; a step of forming an insulating layer having a first main surface and a second main surface facing opposite directions on the metal film in such a manner that the second main surface is in contact with the metal film; a step of forming a conductor layer on the first main surface of the insulating layer; and a step of removing a portion of the metal support after the step of forming the metal film, wherein the first main surface of the insulating layer has first and second regions that are different from each other, and the step of forming the conductor layer comprises using at least one portion of the conductor layer to form a conductive layer. A process for partially forming a wiring extending in a manner of passing through a first area and a second area in a first main surface, wherein the metal film has a third main surface, the third main surface faces a direction opposite to the insulating layer and contacts a metal support body, and in the case where a third area and a fourth area are defined in the third main surface of the metal film and overlap with the first area and the second area of ​​the first main surface respectively when viewed along a cross direction orthogonal to the first main surface, the step of removing a portion of the metal support body comprises the following process: a process of removing a portion of the metal support body located in the third area of ​​the third main surface so that the metal support body does not cover the third area in the third main surface and covers the fourth area in the third main surface.

[0024] In the wiring circuit substrate manufactured by the above-mentioned manufacturing method, a portion of the wiring circuit substrate overlapping the first region of the first main surface and the third region of the third main surface when viewed along the cross direction is referred to as a first substrate portion. In addition, the other portion of the wiring circuit substrate overlapping the second region of the first main surface and the fourth region of the third main surface when viewed along the cross direction is referred to as a second substrate portion.

[0025] 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 film, but does not include a metal support. On the other hand, the second substrate portion includes the rest of the conductor layer, the rest of the insulating layer, the rest of the metal film, and the metal support.

[0026] As described above, the first substrate portion does not include a metal support body. Thus, in the first substrate portion, a higher flexibility than that of the second substrate portion can be ensured. On the other hand, the second substrate portion includes a metal support body. Thus, in the second substrate portion, a certain mechanical strength required for supporting the first substrate portion on other components or for mounting other components can be ensured.

[0027] In addition, in the above-mentioned wiring circuit substrate, the metal film is opposed to a part of the wiring formed in the first area of ​​the first main surface and the other part of the wiring formed in the second area of ​​the first main surface respectively through the insulating layer. Thus, the impedance of a part of the conductor layer and the impedance of the other part of the conductor layer can be adjusted by using the common metal film. Therefore, the situation where the impedance is adjusted unevenly in multiple parts of the conductor layer can be reduced.

[0028] As a result, a printed circuit board having high flexibility and reduced impedance discontinuity can be realized.

[0029] (8) The step of forming the metal thin film may include a step of forming at least a portion of the metal thin film by sputtering.

[0030] In this case, a metal thin film can be easily formed. In addition, the thickness of the sputtered film formed by sputtering can be sufficiently reduced to a degree that does not impair the flexibility of the wiring circuit substrate. Therefore, higher flexibility can be obtained in the first substrate portion.

[0031] (9) The step of forming the metal thin film may include a step of forming at least a portion of the metal thin film by plating.

[0032] In this case, the thickness of the plated layer formed by plating can be adjusted relatively easily, so that a metal thin film having a more appropriate thickness can be formed in order to reduce the impedance of the conductor layer.

[0033] Effects of the Invention According to the present invention, it is possible to realize a printed circuit board having high flexibility and reduced discontinuity in impedance. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a top view of a printed circuit board according to one embodiment of the present invention.

[0035] Figure 2 yes Figure 1 A bottom view of a wiring circuit substrate.

[0036] Figure 3 Yes Figure 1 A schematic cross-sectional view of a wiring circuit substrate obtained by cutting apart multiple parts.

[0037] Figure 4 It is used to illustrate Figure 1 A schematic cross-sectional view of an example of a method for manufacturing a wiring circuit substrate.

[0038] Figure 5 It is used to illustrate Figure 1 A schematic cross-sectional view of an example of a method for manufacturing a wiring circuit substrate.

[0039] Figure 6 It is used to illustrate Figure 1 A schematic cross-sectional view of an example of a method for manufacturing a wiring circuit substrate.

[0040] Figure 7 It is a schematic cross-sectional view obtained by cutting out a plurality of parts of a wired circuit board including a metal thin film according to a first modification.

[0041] Figure 8 It is a schematic cross-sectional view obtained by cutting a plurality of parts of a wired circuit board including a metal thin film according to a second modification.

[0042] Fig. 9 It is a top view of a printed circuit board according to another embodiment.

[0043] Fig.10 Yes Fig. 9 A schematic cross-sectional view of a wiring circuit substrate obtained by cutting apart multiple parts.

[0044] Fig.11 It is a top view of a printed circuit board according to still another embodiment.

[0045] Fig.12 Yes Fig.11 A schematic cross-sectional view of a wiring circuit substrate obtained by cutting apart multiple parts.

[0046] Fig.13 This is a schematic cross-sectional view showing a plurality of cutaway portions of a wired circuit board according to still another embodiment.

[0047] Fig.14 It is a graph showing the measurement results of the impedance of the conductor layer of the wired circuit boards of Comparative Examples 1 and 2 and Examples 1 to 3. DETAILED DESCRIPTION

[0048] Hereinafter, a printed circuit board and a method for manufacturing the same according to an embodiment of the present invention will be described with reference to the drawings.

[0049] 1. Basic structure of wiring circuit board Figure 1 It is a top view of a printed circuit board according to one embodiment of the present invention. Figure 2 yes Figure 1 A bottom view of the wiring circuit substrate 1. Figure 3 Yes Figure 1 Schematic cross-sectional view of a wiring circuit substrate 1 obtained by cutting through multiple parts. Figure 3 middle, Figure 1The AA line cross-sectional view, BB line cross-sectional view and CC line cross-sectional view are sequentially arranged in the upper part, the middle part and the lower part. Here, in order to facilitate the understanding of the structure of the wiring circuit board 1, mutually orthogonal X direction, Y direction and Z direction are defined. Figure 1 In the following drawings, arrows are used to indicate the X direction, the Y direction, and the Z direction as appropriate. In the present embodiment, the X direction and the Y direction are perpendicular to each other in the horizontal plane, and the Z direction corresponds to the vertical direction.

[0050] like Figure 1 and Figure 2 As shown in FIG. 1 , the wiring circuit board 1 according to the present embodiment has a rectangular shape extending in one direction (X direction) when viewed from above. Figure 3 As shown, the wired circuit board 1 mainly has a structure in which a metal support 10, a metal thin film 20, an insulating layer 30, and a conductor layer 40 are sequentially stacked in the Z direction.

[0051] 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, not less than 1 μm and not more than 30 μm. It should be noted that the insulating layer 30 may also be formed of other synthetic resins such as acrylic resin, polyether nitrile resin, polyether sulfone resin, epoxy resin, polyethylene terephthalate resin, polyethylene naphthalate resin, or polyvinyl chloride resin.

[0052] The insulating layer 30 has two main surfaces (upper surface and lower surface) facing opposite directions. In the following description, one main surface (upper surface) of the insulating layer 30 is referred to as a first main surface S1 , and the other main surface (lower surface) of the insulating layer 30 is referred to as a second main surface S2 .

[0053] like Figure 1 As shown by the double-dashed lines, 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 substrate 1 in the long side direction (X direction) of the wiring circuit substrate 1. The two second regions A2 are located at the two ends of the wiring circuit substrate 1 in the long side direction (X direction) of the wiring circuit substrate 1 and the vicinity thereof. Thus, in the X direction, one second region A2 is adjacent to the first region A1, and the other second region A2 is adjacent to the first region A1.

[0054] Two conductor layers 40 are provided on the first main surface S1 of the insulating layer 30. Each conductor layer 40 mainly contains copper and is formed by electrolytic plating on the first main surface S1 of the insulating layer 30. In addition, each conductor layer 40 has a wiring portion 41 and two terminal portions 42. The two terminal portions 42 are respectively arranged in two second areas A2 near the two ends of the wiring circuit substrate 1. Each terminal portion 42 is used to connect other electronic components to the conductor layer 40 of the wiring circuit substrate 1. The wiring portion 41 extends continuously in a manner that passes through one second area A2, the first area A1 and the other second area A2 and connects the two terminal portions 42. The thickness (length in the Z direction) of the conductor layer 40 is, for example, greater than 0.25 μm and less than 50 μm. The width (length in the Y direction) of the wiring portion 41 of the conductor layer 40 is, for example, greater than 0.25 μm and less than 300 μm.

[0055] On the second main surface S2 of the insulating layer 30, a metal film 20 is provided over the entire second main surface S2. The metal film 20 is formed of, for example, a metal or alloy containing one or more elements of copper, chromium, nickel, titanium, iron, molybdenum, and tungsten. The metal film 20 of this example is composed of a single layer containing copper or chromium. The thickness (length in the Z direction) of the metal film 20 is smaller than the thickness (length in the Z direction) of the metal support 10 described later, for example, 20 nm or more and 5 μm or less, preferably 20 nm or more and 3 μm or less.

[0056] The metal thin film 20 has two main surfaces (upper surface and lower surface) facing in opposite directions, similarly to the insulating layer 30 . In the following description, the main surface (lower surface) of the metal thin film 20 facing in the opposite direction to the insulating layer 30 is referred to as a third main surface S3 .

[0057] The third main surface S3 of the metal film 20 is respectively provided with a third area A3 and a fourth area A4 corresponding to the first area A1 and the second area A2 of the first main surface S1 of the insulating layer 30. Specifically, the third area A3 of the third main surface S3 is an area overlapping with the first area A1 of the first main surface S1 when viewed from above along the Z direction. In addition, the fourth area A4 of the third main surface S3 is an area overlapping with the second area A2 of the first main surface S1 when viewed from above along the Z direction.

[0058] On the third main surface S3 of the metal film 20, a metal support 10 is provided in a manner that does not cover the third area A3 and covers the fourth area A4. The metal support 10 includes a metal material different from the metal film 20, for example, a metal or alloy including one or more elements selected from copper, chromium, nickel, titanium, iron, molybdenum and aluminum. Here, the metal material of the metal support 10 is different from the metal material of the metal film 20: between the two metal materials, at least one of the electrical conductivity and the relative magnetic permeability is different to such an extent that it cannot be regarded as substantially the same. In the present embodiment, the metal support 10 is formed of stainless steel. The thickness (length in the Z direction) of the metal support 10 is, for example, greater than 10 μm and less than 250 μm.

[0059] 2. Method for Manufacturing Wired Circuit Board 1 Figures 4 to 6 It is used to illustrate Figure 1 A schematic cross-sectional view of an example of a method for manufacturing a wiring circuit board 1. Figures 4 to 6 In each figure, Figure 3 Similarly, with Figure 1 Three cross-sectional views (corresponding cross-sectional views) corresponding to the AA line, the BB line and the CC line are sequentially arranged in the upper part, the middle part and the lower part.

[0060] First, if Figure 4 As shown, a metal film 20 is formed on the upper surface of the metal support 10. In order to form the metal film 20, a film forming technique such as sputtering, electrolytic plating, electroless plating, chemical vapor deposition or physical vapor deposition is used. As mentioned above, the metal film 20 of this example includes copper or chromium. The lower surface of the metal film 20 in contact with the metal support 10 is the third main surface S3 mentioned above.

[0061] Then, if Figure 5 As shown, an insulating layer 30 including photosensitive polyimide is formed on the upper surface of the metal film 20. The insulating layer 30 is formed by coating the entire upper surface of the metal film 20 with a precursor of the photosensitive polyimide and exposing and developing the precursor. In addition, the formed insulating layer 30 is cured by heating. The upper surface of the insulating layer 30 exposed upward is the above-mentioned first main surface S1, and the lower surface of the insulating layer 30 in contact with the metal film 20 is the above-mentioned second main surface S2. As described above, the first area A1 and the second area A2 are set on the first main surface S1, and the third area A3 and the fourth area A4 are set on the third main surface S3.

[0062] Then, if Figure 6 As shown, one or more (two in this example) conductor layers 40 are formed on the first main surface S1 of the insulating layer 30. Specifically, the conductor layer 40 is formed as follows.

[0063] First, a seed layer including, for example, 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 predetermined pattern (similar to the pattern of FIG. 1 ) is formed on the seed layer. Figure 1 Next, a plating layer containing copper is formed by electrolytic plating on the seed layer exposed through the opening of the plating resist.

[0064] Then, the plating resist is peeled off, and the exposed portion of the seed layer (the portion where the plating layer is not formed) is removed by etching. Thus, the conductor layer 40 including the seed layer and the plating layer is formed. Figure 1 , Figure 6 and the following Figure 8 , Fig.10 , Fig.12 and Fig.13 In the figure, the seed layer and the plating layer constituting the conductor layer 40 are each omitted from illustration.

[0065] It should be noted that a barrier layer for suppressing the diffusion of copper may be formed on the outer surface of the exposed conductor layer 40. As the barrier layer, for example, a nickel thin film may be used. The nickel thin film may be formed, for example, by sputtering or electroless plating. In addition, a protective film for protecting the plurality of wiring portions 41 may be formed on the first main surface S1 of the insulating layer 30 in a manner that covers the plurality of wiring portions 41 and does not cover the plurality of terminal portions 42. As the material of the protective film, for example, photosensitive polyimide may be used. The protective film containing photosensitive polyimide may be formed by the same method as the insulating layer 30.

[0066] Finally, the portion of the metal support 10 located on the third area A3 of the third main surface S3 is removed by, for example, wet etching. At this time, the etching liquid used is an etching liquid that can dissolve the metal support 10 at a higher etching rate than the metal film 20. As a result, the third area A3 of the metal film 20 is exposed downward. Figure 1 to Figure 3 The wiring circuit substrate 1 is completed.

[0067] The above series of treatments can also be performed by a roll-to-roll method. In this case, for example, a roll (hereinafter referred to as a delivery roll) on which a long strip of metal plate made of stainless steel is wound is prepared. The metal plate is delivered from the prepared delivery roll. The metal plate delivered from the delivery roll is wound on another roll. By performing the above series of treatments on each part of the metal plate moving from the delivery roll to the other rolls, a plurality of wiring circuit boards 1 can be efficiently manufactured.

[0068] 3. Effect (1) In the above-mentioned wiring circuit substrate 1, a portion of the wiring circuit substrate 1 that overlaps the first area A1 of the first main surface S1 and the third area A3 of the third main surface S3 when viewed from above along the Z direction is referred to as a first substrate portion. In addition, in the above-mentioned wiring circuit substrate 1, another portion of the wiring circuit substrate 1 that overlaps the second area A2 of the first main surface S1 and the fourth area A4 of the third main surface S3 when viewed from above along the Z direction is referred to as a second substrate portion.

[0069] 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 film 20, and 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 film 20, and the metal support 10.

[0070] Thus, the first substrate portion does not include the metal support 10. Thus, in the first substrate portion, higher flexibility than the second substrate portion can be ensured. On the other hand, the second substrate portion includes the metal support 10. Thus, in the second substrate portion, a certain mechanical strength required for supporting the first substrate portion on other components or for mounting other components can be ensured.

[0071] In addition, in the above-mentioned wiring circuit substrate 1, the metal film 20 is opposed to a part of the wiring portion 41 formed in the first area A1 of the first main surface S1 and the other part of the wiring portion 41 formed in the second area A2 of the first main surface S1, respectively, via the insulating layer 30. Thus, the impedance of a part of the wiring portion 41 and the impedance of the other part of the wiring portion 41 are adjusted by using the common metal film 20. Therefore, it is possible to reduce the situation where the impedance is adjusted unevenly in multiple parts of the wiring portion 41.

[0072] As a result, it is possible to realize a wired circuit board 1 having high flexibility and reduced discontinuity in impedance.

[0073] (2) The first region A1 and the two second regions A2 are adjacent to each other on the first main surface S1 of the insulating layer 30 . Thus, the first substrate portion and the second substrate portion are continuously arranged in the longitudinal direction (X direction) of the wired circuit board 1 , and the first substrate portion is appropriately supported by the second substrate portion.

[0074] (3) The thickness of the metal thin film 20 is smaller than the thickness of the metal support 10 and is 20 nm or more and 5 μm or less. In this case, higher flexibility can be ensured in the first substrate portion. In addition, the impedance of the wiring portion 41 of the conductor layer 40 formed on the first substrate portion and the second substrate portion can be adjusted more appropriately.

[0075] 4. Modification of the Metal Thin Film 20 (1) First Modification The metal thin film 20 provided on the wired circuit board 1 may be composed of a plurality of layers. Figure 7 2 is a schematic cross-sectional view obtained by cutting apart a plurality of parts of a wiring circuit board 1 including a metal thin film 20 according to a first modification. Figure 7 In, with Figure 3 Similarly, with the example Figure 1 The three cross-sectional views corresponding to the AA line, the BB line and the CC line are shown in sequence in the upper part, the middle part and the lower part.

[0076] like Figure 7 As shown, the metal thin film 20 involved in the first modification example is composed of a first thin film layer 20a and a second thin film layer 20b. In order to form each of the first thin film layer 20a and the second thin film layer 20b, a film forming technique such as sputtering, electrolytic plating, electroless plating, chemical vapor deposition or physical vapor deposition is used.

[0077] 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.

[0078] Alternatively, one of the first thin film layer 20a and the second thin film layer 20b may be formed by electrolytic plating. Figure 4 In the process shown, the first thin film layer 20a including copper can be formed by electrolytic plating on the upper surface of the metal support 10. Furthermore, the second thin film layer 20b including a chromium thin film can be formed on the first thin film layer 20a so as to cover the first thin film layer 20a.

[0079] As described later, the degree of reduction in the impedance of the wiring portion 41 varies depending on the thickness of the metal thin film 20. Electrolytic plating can relatively easily adjust the thickness of the formed plated layer by appropriately adjusting the processing conditions such as the 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 electrolytic plating, it is possible to form a metal thin film 20 with a more appropriate thickness in order to reduce the impedance of the wiring portion 41.

[0080] In addition, as described above, when the upper surface of the metal thin film 20 is composed of the second thin film layer 20b including the chromium thin film, by further forming the insulating layer 30 on the second thin film layer 20b, the adhesion between the first thin film layer 20a and the insulating layer 30 is improved. It should be noted that when the first thin film layer 20a is composed of a copper thin film, the second thin film layer 20b may be any one of a nickel thin film, a titanium thin film, a molybdenum thin film, or a tungsten thin film formed by sputtering instead of the chromium thin film. In this case, the adhesion between the first thin film layer 20a and the insulating layer 30 is also improved.

[0081] (2) Second Modification Figure 8 2 is a schematic cross-sectional view obtained by cutting apart a plurality of parts of a wiring circuit board 1 including a metal thin film 20 according to a second modification. Figure 8 In, with Figure 3 Similarly, with the example Figure 1 The three cross-sectional views corresponding to the AA line, the BB line and the CC line are shown in sequence in the upper part, the middle part and the lower part.

[0082] like Figure 8 As shown, the metal thin film 20 involved in the second modification example is composed of a first thin film layer 20a, a second thin film layer 20b and a third thin film layer 20c. In order to form each of the first thin film layer 20a, the second thin film layer 20b and the third thin film layer 20c, a film forming technique such as sputtering, electrolytic plating, electroless plating, chemical vapor deposition or physical vapor deposition is used. The first thin film layer 20a, the second thin film layer 20b and the third thin film layer 20c are respectively 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.

[0083] The first and second film layers 20a and 20b may be chromium and copper films respectively formed by sputtering on the upper surface of the metal support 10. In this case, the third film layer 20c may be a copper plating layer formed by electrolytic plating on the copper film of the second film layer 20b.

[0084] Alternatively, the first film layer 20a may be a copper plating layer formed by electrolytic plating on the upper surface of the metal support 10. In this case, the second film layer 20b and the third film layer 20c may be a copper film and a chromium film respectively formed by sputtering on the plating layer of the first film layer 20a.

[0085] 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 plated layer formed by electrolytic plating on the upper surface of the metal support 10. In addition, the third thin film layer 20c may be a chromium thin film formed by sputtering on the plated layer of the second thin film layer 20b.

[0086] 5. Other Implementation Methods (1) In the first main surface S1 of the insulating layer 30 according to the above embodiment, one of the two second areas A2, the first area A1, and the other of the two second areas A2 are arranged in sequence in the X direction. However, the present invention is not limited to the above example. In the first main surface S1 of the insulating layer 30, the first area A1 and the second area A2 may be arranged as follows.

[0087] Fig. 9 It is a plan view of a wired circuit board 1 according to another embodiment. Fig.10 Yes Fig. 9 Schematic cross-sectional view of a wiring circuit substrate 1 obtained by cutting through multiple parts. Fig.10 middle, Fig. 9 The AA line cross-sectional view, BB line cross-sectional view and CC line cross-sectional view are arranged in the upper part, the middle part and the lower part respectively. Fig. 9 and Fig.10 The wiring circuit substrate 1 is Figure 1 The differences between the wiring circuit board 1 and the wiring circuit board 1 will be described.

[0088] exist Fig. 9 In the wiring circuit substrate 1, a first region A1 and a second region A2 are set on the first main surface S1 of the insulating layer 30. The first region A1 is set in an island shape in the center of the long side direction (X direction) and the short side direction (Y direction) of the wiring circuit substrate 1. On the other hand, the second region A2 is set to surround the first region A1. Figure 1 Similarly, in the wired circuit board 1, most of the wiring portions 41 of the two conductor layers 40 are located in the first area A1, and 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 in the second area A2.

[0089] As described above, the first area A1 and the second area A2 are set on the first main surface S1. Therefore, in the wiring circuit board 1 of this example, the third area A3 (not shown) overlapping with the first area A1 of the first main surface S1 when viewed from above along the Z direction is set on the third main surface S3 of the metal film 20. In addition, the fourth area A4 (not shown) overlapping with the second area A2 of the first main surface S1 when viewed from above along the Z direction is set.

[0090] Therefore, if Fig.10 As shown, 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 film 20 over the entire X direction. Specifically, in the wiring circuit board 1 of this example, Fig.10 As shown in the center of FIG. 4 , a linear metal support 10 is provided near the wiring portion 41 of each conductor layer 40 so as to extend in parallel with the wiring portion 41. Thus, a desired mechanical strength can be obtained in the region near the wiring portion 41.

[0091] In this way, by appropriately providing the metal support 10 at a plurality of portions in the wired circuit board 1 , it is possible to impart desired flexibility and desired mechanical strength to each of the plurality of portions of the wired circuit board 1 .

[0092] (2) The wired circuit board 1 according to the above embodiment has a rectangular shape extending in one direction (X direction) in a plan view, but the present invention is not limited thereto. The wired circuit board 1 may have the following shapes.

[0093] Fig.11 It is a plan view of a wired circuit board 1 according to still another embodiment. Fig.12 Yes Fig.11 Schematic cross-sectional view of a wiring circuit substrate 1 obtained by cutting through multiple parts. Fig.12 middle, Fig.11 The AA line cross-sectional view, BB line cross-sectional view and CC line cross-sectional view are arranged in the upper part, the middle part and the lower part respectively. Fig.11 and Fig.12 The wiring circuit substrate 1 is Figure 1 The differences between the wiring circuit board 1 and the wiring circuit board 1 will be described.

[0094] like Fig.11 and Fig.12 As shown, the wiring circuit board 1 of this example is formed so that the width (length in the Y direction) of the insulating layer 30 changes stepwise in the direction in which the wiring portions 41 of the two conductor layers 40 extend. Specifically, the insulating layer 30 is formed so that it is larger at the two ends and the vicinity thereof in the long side 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 area A1 set on the first main surface S1 is smaller than the width (length in the Y direction) of the second area A2. According to this structure, higher flexibility can be obtained in the portion of the wiring circuit board 1 located between the two second areas A2.

[0095] (3) In the wired circuit board 1 according to the above embodiment, the metal thin 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 metal thin film 20 .

[0096] Fig.13 2 is a schematic cross-sectional view obtained by cutting apart a plurality of parts of a wiring circuit board 1 according to another embodiment. Figure 1 The top view of the wiring circuit substrate 1 is the same. Fig.13 In, with Figure 3 Similarly, with Figure 1 The three cross-sectional views corresponding to the AA line, the BB line and the CC line are shown in sequence in the upper part, the middle part and the lower part.

[0097] exist Fig.13 In the wiring circuit board 1, 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, the metal film 20 is also formed to be opposed to the entire conductor layer 40 via the insulating layer 30, so the same effect as the above embodiment can be obtained.

[0098] (4) When manufacturing the wired 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 .

[0099] (5) In the wired 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 the metal thin film 20 only needs to overlap the entire conductive layer 40 .

[0100] For example, in the first main surface S1 of the wiring circuit substrate 1 involved in the above embodiment, the first area A1 and the second area A2 may be set to be separated from each other in the X direction via other new areas. Here, when the wiring portion 41 of the conductor layer 40 is located on the other new areas, the metal film 20 is formed to overlap with the first area A1 and the second area A2 and the other new areas when viewed from above along the Z direction. On the other hand, when the wiring portion 41 of the conductor layer 40 is not located on the other new areas, the metal film 20 may be formed to overlap with the first area A1 and the second area A2 and not overlap with the other new areas when viewed from above along the Z direction.

[0101] 6. Correspondence between the various structural elements of the technical solution and the various parts of the implementation method Hereinafter, examples of correspondence between the components of the claims and the components of the embodiments will be described, but the present invention is not limited to the following examples. As the components of the claims, various other components having the structures or functions described in the claims may also be used.

[0102] In the above-mentioned embodiment, the wiring circuit substrate 1 is an example of a wiring circuit substrate, the first principal surface S1 is an example of a first principal surface, the second principal surface S2 is an example of a second principal surface, the insulating layer 30 is an example of an insulating layer, the conductive layer 40 is an example of a conductive layer, the third principal surface S3 is an example of a third principal surface, and the metal film 20 is an example of a metal film.

[0103] In addition, the first area A1 is an example of a first area, the second area A2 is an example of a second area, the wiring portion 41 is an example of wiring, the third area A3 is an example of a third area, the fourth area A4 is an example of a fourth area, the first thin film layer 20a is an example of a first metal film, and the second thin film layer 20b is an example of a second metal film.

[0104] 7. Test on the Effect of Reducing the Impedance of the Wiring Section 41 by the Metal Thin Film 20 The inventors of the present invention prepared wired circuit boards of Comparative Examples 1 and 2 and Examples 1 to 3 in order to confirm the degree of reduction in impedance of various types of metal thin films 20 and the wiring portions 41 corresponding to the types.

[0105] Specifically, the inventors of the present invention prepared the following wiring circuit board as a wiring circuit board of Comparative Example 1. That is, the wiring circuit board has the same structure as that of Comparative Example 1 except that the metal support 10 and the metal thin film 20 are not included. Figure 1 to Figure 3 A wiring circuit substrate having the same structure as the wiring circuit substrate 1.

[0106] In addition, the inventors of the present invention prepared the following wiring circuit substrate as a wiring circuit substrate of Comparative Example 2, that is, the wiring circuit substrate having the same structure as that of Comparative Example 2 except that the metal thin film 20 is not provided and the metal support 10 is provided in contact with the entire second main surface S2 of the insulating layer 30. Figure 1 to Figure 3 A wired circuit substrate having the same structure as the wired circuit substrate 1 of Comparative Example 2. In the wired circuit substrate of Comparative Example 2, the thickness (length in the Z direction) of the metal support 10 is 18 μm.

[0107] In addition, the inventors of the present invention prepared the following wiring circuit substrate as the wiring circuit substrate of Example 1, that is, Figure 1 to Figure 3 A wiring circuit substrate having the same structure as the wiring circuit substrate 1 of the embodiment 1 and in which the metal thin film 20 is formed of a single layer containing chromium. The metal thin film 20 of chromium is formed by sputtering. In the wiring circuit substrate of the embodiment 1, the thickness (length in the Z direction) of the metal thin film 20 is 50 nm.

[0108] In addition, the inventors of the present invention prepared the following wiring circuit substrate as a wiring circuit substrate of Example 2, that is, Figure 1 to Figure 3 A wiring circuit substrate having the same structure as the wiring circuit substrate 1 of the embodiment 2 and in which the metal thin film 20 is formed of a single layer containing copper. The metal thin film 20 of copper is formed by sputtering. In the wiring circuit substrate of the embodiment 2, the thickness (length in the Z direction) of the metal thin film 20 is 50 nm.

[0109] In addition, the inventors of the present invention prepared the following wiring circuit substrate as a wiring circuit substrate of Example 3, that is, Figure 7 A wiring circuit substrate having the same structure as the wiring circuit substrate 1 of the embodiment 3. The first thin film layer 20a contains chromium and is formed by sputtering. The second thin film layer 20b contains copper and is formed by sputtering. In the wiring circuit substrate of the embodiment 3, the thickness (length in the Z direction) of the first thin film layer 20a is 50nm, and the thickness (length in the Z direction) of the second thin film layer 20b is 50nm. Therefore, the thickness (length in the Z direction) of the metal thin film 20 is 100nm.

[0110] It should be noted that the length, width, interval, thickness and other dimensions of the two wiring portions 41 are equal between the wiring circuit substrates of Comparative Examples 1 and 2 and Examples 1 to 3. In addition, the thickness of the insulating layer 30 is also equal between the wiring circuit substrates of Comparative Examples 1 and 2 and Examples 1 to 3.

[0111] For the plurality of wired circuit boards produced as described above, the impedance of the conductor layer 40 was measured by TDR (Time Domain Reflectometry) method. Fig.14 It is a graph showing the measurement results of the impedance of the conductor layer 40 of the wired circuit boards of Comparative Examples 1 and 2 and Examples 1 to 3.

[0112] exist Fig.14 In the embodiment, the impedance measurement result is shown by a curve graph. In the curve graph, the vertical axis represents impedance and the horizontal axis represents time. Fig.14 In the graph, the measurement result of the impedance corresponding to the conductor layer 40 of Comparative Example 1 is indicated by a dotted line, and the measurement result of the impedance corresponding to the conductor layer 40 of Comparative Example 2 is indicated by a solid line. In addition, the measurement result of the impedance corresponding to the conductor layer 40 of Example 1 is indicated by a thick solid line, the measurement result of the impedance corresponding to the conductor layer 40 of Example 2 is indicated by a thick dotted line, and the measurement result of the impedance corresponding to the conductor layer 40 of Example 3 is indicated by a thick double-dashed line. Fig.14In the graph of , the impedance shown in the range of about 200 ps or more and about 400 ps or less on the horizontal axis (time axis) represents the impedance corresponding to the wiring portion 41 of each wiring circuit board.

[0113] according to Fig.14 , the impedance of the wiring portion 41 of Comparative Example 1 is higher than the impedance of the wiring portion 41 of Comparative Example 2 and Examples 1 to 3. In contrast, the impedance of the wiring portion 41 of Comparative Example 2 is sufficiently lower than the impedance of the wiring portion 41 of Comparative Example 1 and Examples 1 to 3.

[0114] The impedance of the wiring portion 41 of Examples 1 and 2 is substantially the same, sufficiently lower than the impedance of the wiring portion 41 of Comparative Example 1, and slightly higher than the impedance of the wiring portion 41 of Comparative Example 2 and Example 3. The impedance of the wiring portion 41 of Example 3 is sufficiently lower than the impedance of the wiring portion 41 of Comparative Example 1, and is between the impedance of the wiring portion 41 of Comparative Example 2 and the impedance of the wiring portion 41 of Examples 1 and 2.

[0115] Here, in the wiring circuit substrate of Comparative Example 2, the portion of the metal support 10 overlapping each wiring portion 41 when viewed from above along the Z direction functions as an impedance reducing layer that reduces the impedance of the wiring portion 41. On the other hand, in each of the wiring circuit substrates of Examples 1 to 3, the portion of the metal thin film 20 overlapping each wiring portion 41 when viewed from above functions as an impedance reducing layer that reduces the impedance of the wiring portion 41.

[0116] The thickness of the metal support 10 functioning as the impedance reduction layer in the wiring circuit board of Comparative Example 2 is greater than the thickness of the metal thin film 20 functioning as the impedance reduction layer in the wiring circuit boards of Examples 1 to 3. In addition, the thickness of the metal thin film 20 functioning as the impedance reduction layer in the wiring circuit board of Example 3 is greater than the thickness of the metal thin film 20 functioning as the impedance reduction layer in the wiring circuit boards of Examples 1 and 2. Considering these points, it can be seen that the greater the thickness of the impedance reduction layer, the greater the degree of reduction in the impedance of the wiring portion 41, and the smaller the thickness of the impedance reduction layer, the smaller the degree of reduction in the impedance of the wiring portion 41. Therefore, when manufacturing the wiring circuit board 1 involved in the present invention, it is preferable to adjust the thickness of the metal thin film 20 overlapping the wiring portion 41 in a plan view according to the required degree of impedance reduction.

Claims

1. A wiring circuit substrate, comprising: An insulating layer having a first main surface and a second main surface facing in opposite directions to each other; a conductor layer, disposed on the first main surface of the insulating layer; a metal film disposed on the second main surface of the insulating layer and having a third main surface facing a direction opposite to the insulating layer; as well as a metal support including a metal material different from the metal material of at least a part of 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, At least a portion of the conductor layer constitutes a wiring extending through the first region and the second region of the first main surface. In a case where a third region and a fourth region are defined in the third main surface of the metal film, which respectively overlap with the first region and the second region of the first main surface when observed along a cross direction orthogonal to the first main surface, the metal support body is arranged on the third main surface in a manner not covering the third region in the third main surface and covering the fourth region in the third main surface.

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

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

4. The wired circuit substrate according to any one of claims 1 to 3, wherein The metal film includes a plating layer.

5. The wired circuit substrate according to any one of claims 1 to 4, wherein: The thickness of the metal film is smaller than the thickness of the metal support.

6. The wired circuit substrate according to any one of claims 1 to 5, wherein: The thickness of the metal thin film is greater than or equal to 20 nm and less than or equal to 5 μm.

7. A method for manufacturing a wiring circuit substrate, comprising: a step of preparing a metal support; forming a metal thin film including a metal material different from that of the metal support on the metal support; A step of forming an insulating layer having a first main surface and a second main surface facing in opposite directions on the metal film in such a manner that the second main surface is in contact with the metal film; forming a conductor layer on the first main surface of the insulating layer; and a step of removing a portion 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 the step of forming a wiring extending through the first region and the second region of the first main surface using at least a portion of the conductor layer. The metal film has a third main surface, the third main surface faces the direction opposite to the insulating layer and contacts the metal support. In a case where a third region and a fourth region are defined in the third main surface of the metal film, which respectively overlap with the first region and the second region of the first main surface when observed along a cross direction orthogonal to the first main surface, the step of removing a portion of the metal support body includes the following steps: a step of removing the portion of the metal support body located in the third region of the third main surface so that the metal support body does not cover the third region in the third main surface and covers the fourth region in the third main surface.

8. The method for manufacturing a wired circuit board according to claim 7, wherein: The step of forming the metal thin film includes a process of forming at least a portion of the metal thin film by sputtering.

9. The method for manufacturing a wired circuit board according to claim 7 or 8, wherein: The step of forming the metal thin film includes a process of forming at least a portion of the metal thin film by plating.

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