Wired circuit board and method of manufacturing the same

Abstract

To provide a wiring circuit board capable of suppressing peeling of a cover insulating layer from a wiring layer while reducing electric resistance in the wiring layer, and to provide a manufacturing method of the same.SOLUTION: A wiring circuit board 1 includes: a base insulating layer 2; a first wiring layer 7 arranged on one side in the thickness direction of the base insulating layer 2; and a cover insulating layer 3 arranged on one surface in the thickness direction of the base insulating layer 2 so as to cover the first wiring layer 7. The first wiring layer 7 includes: a first wiring part 8 in contact with one surface of the base insulating layer; and a second wiring part 9 in contact with one surface of the thickness direction of the first wiring part. Both end surfaces of the second wiring part 9 in the width direction orthogonal to the thickness direction and the transmission direction are arranged on the inner side in the width direction from both end surfaces of the first wiring part 8.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] BACKGROUND ART Conventionally, there has been known a wired circuit board that includes an insulating base layer, a wiring layer formed thereon and having a rectangular cross section, and an insulating cover layer that covers the wiring layer (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-119599 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been a demand for wiring circuit boards to efficiently transmit large currents through their wiring layers.

[0005] Therefore, it has been proposed to increase the width or thickness of the wiring layer to increase the cross-sectional area and thereby reduce the electrical resistance of the wiring layer. Considering that the width of the wiring layer may not be increased when the installation space for the wiring layer is limited, a method of increasing the thickness of the wiring layer has been proposed in particular.

[0006] However, in this case, there is a problem in that the insulating cover layer is easily peeled off from both ends in the width direction at the upper ends of the wiring.

[0007] The present invention provides a wired circuit board that can reduce the electrical resistance in the wiring layer while suppressing peeling of the cover insulating layer from the wiring layer, and a method for manufacturing the same. [Means for solving the problem]

[0008] The present invention (1) includes a wired circuit board comprising a base insulating layer, a wiring layer arranged on one thickness-wise side of the base insulating layer, and a cover insulating layer arranged on one thickness-wise surface of the base insulating layer so as to cover the wiring layer, wherein the wiring layer comprises a first wiring portion contacting the one thickness-wise surface of the base insulating layer and a second wiring portion contacting the one thickness-wise surface of the first wiring portion, and both end faces in a width direction perpendicular to the thickness direction and the transmission direction of the second wiring portion are arranged inward in the width direction from both end faces of the first wiring portion.

[0009] In this wired circuit board, the wiring layer includes a first wiring portion and a second wiring portion, which increases the cross-sectional area and reduces the electrical resistance of the wiring layer.

[0010] Furthermore, both end faces in the width direction of the second wiring portion are located more inward in the width direction than both end faces of the first wiring portion. Therefore, two steps can be formed by the first wiring portion and the second wiring portion at each end in the width direction of the wiring layer. Therefore, the cover insulating layer has an anchor effect of covering these steps, which can suppress peeling of the cover insulating layer from the wiring layer.

[0011] The present invention (2) includes the wired circuit board according to (1), in which the ratio (T2 / T1) of the thickness T2 of the second wiring portion to the thickness T1 of the first wiring portion is 0.7 or more and 3.0 or less.

[0012] In this wiring circuit board, the ratio (T2 / T1) of the thickness T2 of the second wiring portion to the thickness T1 of the first wiring portion is 0.7 or more and 3.0 or less, so that the cross-sectional area of ​​the wiring layer can be increased while reliably achieving the anchor effect and more reliably suppressing peeling of the cover insulating layer from the wiring layer.

[0013] The present invention (3) includes the wired circuit board described in (1) or (2), in which the wiring layer further includes a third wiring portion that contacts one surface of the base insulating layer in the thickness direction, and a fourth wiring portion that is spaced apart from the third wiring portion on one side in the thickness direction.

[0014] In this wired circuit board, the wiring layer includes the third wiring portion and the fourth wiring portion, and therefore the third wiring portion and the fourth wiring portion can be used for the same purpose as the first wiring portion and the second wiring portion or for a different purpose, allowing the wiring layer to be used for a wide range of purposes.

[0015] The present invention (4) includes the wired circuit board according to (3), in which the wiring layer comprises a first pattern portion including the first wiring portion and the second wiring portion, and a second pattern portion including the third wiring portion and the fourth wiring portion and independent of the first pattern portion.

[0016] In this wired circuit board, the wiring layer includes a first pattern and a second pattern that is independent of the first pattern, so that each of these patterns can be used for a different purpose.

[0017] The present invention (5) is a method for manufacturing a wired circuit board according to (4), and includes the method for manufacturing a wired circuit board, which includes the steps of forming the base insulating layer, forming the first wiring portion and the third wiring portion, simultaneously forming the second wiring portion and the fourth wiring portion, and forming the cover insulating layer.

[0018] In this method, the second wiring portion included in the first pattern and the fourth wiring portion included in the second pattern are formed simultaneously, so that the second wiring portion and the fourth wiring portion included in different patterns can be easily formed at once. [Effects of the Invention]

[0019] According to the wired circuit board of the present invention, the electrical resistance of the wiring layer can be reduced, and peeling of the cover insulating layer from the wiring layer can be suppressed.

[0020] According to the method for manufacturing a wired circuit board of the present invention, the second wiring portion and the fourth wiring portion included in different patterns can be easily formed at once. [Brief explanation of the drawings]

[0021] [Figure 1]1A and 1B are enlarged views of one embodiment of the wired circuit board of the present invention, with FIG. 1A being a plan view and FIG. 1B being a front cross-sectional view taken along line XX in FIG. 1A. [Figure 2] 2A and 2B are side cross-sectional views of the wired circuit board shown in FIGS. 1A and 1B, where FIG. 2A is a cross-sectional view taken along line YY in FIGS. 1A and 1B, and FIG. 2B is a cross-sectional view taken along line ZZ in FIGS. 1A and 1B. [Figure 3] Figures 3A to 3E are manufacturing process diagrams for the wired circuit board shown in Figure 1B, where Figure 3A shows the process of preparing a base insulating layer, Figure 3B shows the process of forming the first wiring portion and the third wiring portion, Figure 3C shows the process of forming the first cover insulating layer, Figure 3D shows the process of forming the second wiring portion and the fourth wiring portion, and Figure 3E shows the process of forming the second cover insulating layer. [Figure 4] FIG. 4 is a cross-sectional view of a modified example (an embodiment in which the first pattern portion has a second insulating cover layer) of the wired circuit board shown in FIG. 1B. [Figure 5] FIG. 5 is a cross-sectional view of a modified example of the wired circuit board shown in FIG. 1B (an embodiment in which the second insulating cover layer contacts part of the side surface of the second wiring portion). [Figure 6] FIG. 6 is a cross-sectional view of a modified example of the wired circuit board shown in FIG. 1B (an embodiment in which the second insulating cover layer is in contact with part of one surface in the thickness direction of the first wiring portion). [Figure 7] FIG. 7 is a cross-sectional view of a modified example (an aspect in which the overhanging portion is continuous with the second wiring portion) of the wired circuit board shown in FIG. 1B. [Figure 8] Figures 8A and 8B show a modified example of the wired circuit board shown in Figures 1A and 1B (an embodiment in which the second pattern portion is not provided and the first pattern portion is provided), where Figure 8A is a plan view and Figure 8B is a side cross-sectional view along line ZZ in Figure 8A. [Figure 9] Figures 9A to 9E are cross-sectional views of a wired circuit board, showing steps of a method for manufacturing another wired circuit board, where Figure 9A shows the step of forming a first wiring portion, Figure 9B shows the step of forming a second wiring portion and a third wiring portion, Figure 9C shows the step of forming a first cover insulating layer, Figure 9D shows the step of forming a fourth wiring portion, and Figure 9E shows the step of forming a second cover insulating layer. [Figure 10]FIG. 10 is a cross-sectional view of the wired circuit board of Comparative Example 1. As shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0022] <One embodiment> An embodiment of the wired circuit board of the present invention will be described with reference to Figures 1A to 2B. In Figure 1A, the cover insulating layer 3 (described later) is omitted to clearly show the relative position of the wiring layer 6 (described later).

[0023] The wired circuit board 1 has a predetermined thickness and a flat band shape extending long in the front-to-rear direction (the vertical direction in the plane of the paper in FIG. 1A, and the depth direction in the plane of the paper in FIG. 1B). The wired circuit board 1 includes an insulating base layer 2, a wiring layer 6 disposed on one side of the insulating base layer 2 in the thickness direction, and an insulating cover layer 3 that covers the wiring layer 6.

[0024] In plan view, the base insulating layer 2 has the same outer shape as the wired circuit board 1. Examples of materials for the base insulating layer 2 include insulating resins such as polyimide. The thickness of the base insulating layer 2 is, for example, 5 μm or more and, for example, 30 μm or less.

[0025] The wiring layer 6 includes a first wiring layer 7, a second wiring layer 10, and a third wiring layer 12. The wiring layer 6 is made of a conductor such as copper. The wiring layer 6 extends in a front-to-back direction. That is, the direction in which the wiring layer 6 extends is both the transmission direction and the front-to-back direction. The shape, arrangement, and dimensions of the wiring layer 6 will be described in detail later.

[0026] The insulating cover layer 3 is disposed on one surface in the thickness direction of the insulating base layer 2. The insulating cover layer 3 covers the wiring layer 6. Examples of materials for the insulating cover layer 3 include insulating resins such as polyimide.

[0027] The wired circuit board 1 also includes a first pattern portion 4 and a second pattern portion 5. The first pattern portion 4 is on one side of the wired circuit board 1 in the width direction (a direction perpendicular to the thickness direction and the front-to-rear direction), and the second pattern portion 5 is on the other side of the wired circuit board 1 in the width direction. The first pattern portion 4 and the second pattern portion 5 are spaced apart from each other in the width direction. A margin portion 19 is provided between the first pattern portion 4 and the second pattern portion 5. The margin portion 19 does not include the cover insulating layer 3 and the wiring layer 6 (described later), but includes only the base insulating layer 2.

[0028] As shown in the left diagram of FIG. 1B and in FIG. 2A, the first pattern portion 4 includes a base insulating layer 2, a first wiring layer 7, and a cover insulating layer 3.

[0029] The first wiring layer 7 is, for example, a power supply wiring for transmitting a power supply current (for example, a large current of 10 mA or more, or even 100 mA or more). (1st wiring) The first wiring layer 7 is an example of a first pattern.

[0030] The first wiring layer 7 has a generally rectangular shape in a plan view extending in the front-to-back direction, or has a generally convex (inverted T) shape in a cross section perpendicular to the transmission direction and thickness direction of the first wiring layer 7.

[0031] 1B, the first wiring layer 7 includes a first wiring portion 8 and a second wiring portion 9 that is narrower than the first wiring portion 8, arranged in this order toward one side in the thickness direction. Preferably, the first wiring layer 7 includes only the first wiring portion 8 and the second wiring portion 9.

[0032] The first wiring portion 8 is the other thickness direction portion of the first wiring layer 7. The first wiring portion 8 is disposed on one thickness direction surface of the base insulating layer 2. The first wiring portion 8 has a generally rectangular shape that is long in the width direction. The other thickness direction surface of the first wiring portion 8 is entirely in contact with one thickness direction surface of the base insulating layer 2.

[0033] The second wiring portion 9 is located at one thickness direction portion of the first wiring layer 7. The second wiring portion 9 is located at the width direction intermediate portion (between both ends) of one thickness direction surface of the first wiring portion 8. The second wiring portion 9 has a substantially rectangular shape in a cross section perpendicular to the transmission direction and thickness direction of the first wiring layer 7. The entire other thickness direction surface of the second wiring portion 9 does not contact both width direction ends of one thickness direction surface of the first wiring portion 8, but contacts the width direction intermediate portion of one thickness direction surface.

[0034] As a result, in the first wiring layer 7, both end faces of the second wiring portion 9 in the width direction are arranged more inward than both end faces of the first wiring portion 8 in the width direction.

[0035] At one widthwise end of the first wiring layer 7, two one-side steps 17 are formed, each consisting of a side end face and one thicknesswise face of the first wiring portion 8 and a side end face and one thicknesswise face of the second wiring portion 9. At the other widthwise end of the first wiring layer 7, two other-side steps 18 are formed, each consisting of a side end face and one thicknesswise face of the first wiring portion 8 and a side end face and one thicknesswise face of the second wiring portion 9.

[0036] The above-mentioned first wiring portion 8 and second wiring portion 9 constitute a first pattern.

[0037] The thickness T1 of the first wiring portion 8 is, for example, 3 μm or more, preferably 5 μm or more, and for example, 40 μm or less, preferably 25 μm or less. The thickness T2 of the second wiring portion 9 is, for example, 3 μm or more, preferably 5 μm or more, and for example, 50 μm or less, preferably 30 μm or less. The ratio (T2 / T1) of the thickness T2 of the second wiring portion 9 to the thickness T1 of the first wiring portion 8 is, for example, 0.7 or more, preferably 0.9 or more, more preferably 1.0 or more, and for example, 3.0 or less, preferably 2.0 or less, more preferably 1.5 or less. The thickness T1 of the first wiring portion 8 is the length between one thickness-direction surface of the first wiring portion 8 and one thickness-direction surface of the base insulating layer 2. The thickness T2 of the second wiring portion 9 is the length between one thickness-direction surface of the second wiring portion 9 and one thickness-direction surface of the first wiring portion 8. If the ratio is within the above range, the cross-sectional area of ​​the first wiring layer 7 can be increased while the anchor effect of the cover insulating layer 3 (second cover insulating layer 16) on the first wiring layer 7 can be reliably achieved, and peeling of the cover insulating layer 3 from the first wiring layer 7 can be more reliably suppressed.

[0038] The width of the first wiring portion 8 is, for example, 10 μm or more, preferably 20 μm or more, more preferably 30 μm or more, and for example, 500 μm or less, preferably 250 μm or less. The width of the first wiring portion 8 is the distance between both end faces of the first wiring portion 8 in the width direction. If the width of the first wiring portion 8 is equal to or less than the above-mentioned upper limit, the first wiring layer 7 can be arranged even in a narrow space. The width of the second wiring portion 9 is, for example, 5 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and for example, 450 μm or less, preferably 200 μm or less. The width of the second wiring portion 9 is the distance between both end faces of the second wiring portion 9 in the width direction. The ratio of the width of the second wiring portion 9 to the width of the first wiring portion 8 is, for example, 0.8 or less, preferably 0.6 or less, and for example, 0.1 or more, preferably 0.3 or more.

[0039] The thickness of the first wiring layer 7 is the sum of the thickness T1 of the first wiring portion 8 and the thickness T2 of the second wiring portion 9. The width of the first wiring layer 7 is the same as the width of the first wiring portion 8.

[0040] Terminals (not shown) are connected to both ends of the first wiring layer 7 in the front-to-rear direction. The terminals are electrically connected to electrodes. The electrodes are provided on a power supply device for inputting a power supply current to the first wiring layer 7 and a driving device for extracting the power supply current from the first wiring layer 7.

[0041] 1B and 2A, in the first pattern portion 4, the insulating cover layer 3 includes the second insulating cover layer 16. Specifically, in this embodiment, the insulating cover layer 3 includes only the second insulating cover layer 16.

[0042] 1B, the second cover insulating layer 16 covers the first wiring layer 7. Specifically, the second cover insulating layer 16 contacts a portion of one thickness-wise surface of the base insulating layer 2 near the outside of the first wiring portion 8, both width-wise end faces and one thickness-wise surface of the first wiring portion 8, and both width-wise end faces and one thickness-wise surface of the second wiring portion 9. More specifically, the second cover insulating layer 16 contacts (is in close contact with) two one-side steps 17 and two other-side steps 18 of the first wiring layer 7. The second cover insulating layer 16 is fixed to each of both width-wise end portions of the first wiring layer 7.

[0043] The length between one thickness-wise surface of the second insulating cover layer 16 and one thickness-wise surface of the second wiring portion 9 corresponds to the thickness of the second insulating cover layer 16, and is, for example, 5 μm or more and, for example, 50 μm or less.

[0044] As shown in the right-hand diagram of Figure 1B and Figure 2B, the second pattern portion 5 includes a base insulating layer 2, a second wiring layer 10, a first cover insulating layer 15, a third wiring layer 12, and a second cover insulating layer 16.

[0045] The base insulating layer 2 in the second pattern portion 5 is the same layer as the base insulating layer 2 in the first pattern portion 4.

[0046] The second wiring layer 10 is, for example, a signal wiring for transmitting an electric signal (for example, a weak current of less than 10 mA, or even less than 1 mA). The second wiring layer 10 includes a substantially rectangular third wiring portion 13. Preferably, the second wiring layer 10 includes only the third wiring portion 13.

[0047] The third wiring portion 13 is disposed on one thickness-wise surface of the base insulating layer 2. The entire other thickness-wise surface of the third wiring portion 13 is in contact with one thickness-wise surface of the base insulating layer 2. The thickness T3 of the third wiring portion 13 is, for example, the same as the thickness T1 of the first wiring portion 8. The width of the third wiring portion 13 is not particularly limited, and in this embodiment, it is, for example, the same as the width of the second wiring portion 9. Therefore, in this embodiment, the width of the third wiring portion 13 is narrower than the width of the first wiring portion 8.

[0048] The first cover insulating layer 15 covers the third wiring portion 13 in a cross section perpendicular to the transmission direction and thickness direction of the first wiring layer 7. Specifically, the first cover insulating layer 15 contacts a portion near the outside of the third wiring portion 13 on one thickness-direction surface of the base insulating layer 2, and both width-direction end faces and one thickness-direction surface of the third wiring portion 13. The length between one thickness-direction surface of the first cover insulating layer 15 and one thickness-direction surface of the third wiring portion 13 corresponds to the thickness of the first cover insulating layer 15 and is, for example, 5 μm or more and, for example, 50 μm or less.

[0049] The third wiring layer 12 is, for example, a signal wiring for transmitting an electric signal (for example, a weak current of less than 10 mA, or even less than 1 mA). The third wiring layer 12 includes a substantially rectangular fourth wiring portion 14. Preferably, the third wiring layer 12 includes only the fourth wiring portion 14.

[0050] The fourth wiring portion 14 is disposed on one thickness-wise surface of the first insulating cover layer 15. The other thickness-wise surface of the fourth wiring portion 14 is entirely in contact with one thickness-wise surface of the first insulating cover layer 15. When projected in the thickness direction, the fourth wiring portion 14 overlaps the third wiring portion 13. Specifically, the planar shape of the fourth wiring portion 14 matches the planar shape of the third wiring portion 13. The thickness T4 of the fourth wiring portion 14 is, for example, the same as the thickness T3 of the third wiring portion 13. The width of the fourth wiring portion 14 is the same as the width of the third wiring portion 13.

[0051] The second wiring layer 10 and the third wiring layer 12 are an example of a second pattern. The third wiring portion 13 and the fourth wiring portion 14 form the second pattern.

[0052] The second cover insulating layer 16 covers the fourth wiring portion 14. Specifically, the second cover insulating layer 16 contacts a portion of one thickness-direction surface of the first cover insulating layer 15 near the outside of the fourth wiring portion 14, and both width-direction end faces and one thickness-direction surface of the fourth wiring portion 14. The length between one thickness-direction surface of the second cover insulating layer 16 and one thickness-direction surface of the fourth wiring portion 14 corresponds to the thickness of the second cover insulating layer 16 and is, for example, 5 μm or more and, for example, 50 μm or less.

[0053] The above-mentioned first insulating cover layer 15 and second insulating cover layer 16 are provided in the insulating cover layer 3. Preferably, the insulating cover layer 3 in the second pattern portion 5 includes only the first insulating cover layer 15 and the second insulating cover layer 16.

[0054] Next, a method for manufacturing this wired circuit board 1 will be described with reference to Figures 3A to 3E. The method for manufacturing the wired circuit board 1 includes a first step of preparing the base insulating layer 2, a second step of forming the first wiring portion 8 and the third wiring portion 13, a third step of forming the first cover insulating layer 15, a fourth step of forming the second wiring portion 9 and the fourth wiring portion 14, and a fifth step of forming the second cover insulating layer 16. The first to fifth steps are carried out in order.

[0055] As shown in FIG. 3A, in the first step, for example, a photosensitive insulating resin composition is subjected to photolithography to form the insulating base layer 2.

[0056] 3B, in the second step, the first wiring portion 8 and the third wiring portion 13 are simultaneously formed by a pattern formation method such as an additive method or a subtractive method. In the second pattern portion 5, a second wiring layer 10 (signal wiring) including the third wiring portion 13 is formed.

[0057] 3C, in the third step, for example, a photosensitive insulating resin composition is applied to one surface in the thickness direction of the base insulating layer 2 so as to cover the first wiring portion 8 and the third wiring portion 13, and then photolithography is performed. As a result, a first cover insulating layer 15 that covers the third wiring portion 13 is formed in the second pattern portion 5.

[0058] 3D, in the fourth step, the second wiring portion 9 and the fourth wiring portion 14 are simultaneously formed by a pattern formation method such as an additive method or a subtractive method. As a result, in the first pattern portion 4, a first wiring layer 7 (power supply wiring) including the first wiring portion 8 and the second wiring portion 9 is formed. In addition, in the second pattern portion 5, a third wiring layer 12 (signal wiring) including the fourth wiring portion 14 is formed.

[0059] As shown in Fig. 3E, in the fifth step, for example, a photosensitive insulating resin composition is applied to one surface in the thickness direction of the base insulating layer 2 and the first cover insulating layer 15 so as to cover the second wiring portion 9 and the fourth wiring portion 14, and then photolithography is performed. As a result, the second cover insulating layer 16 is formed in both the first pattern portion 4 and the second pattern portion 5. As a result, the cover insulating layer 3 including the second cover insulating layer 16 is formed in the first pattern portion 4. As a result, the cover insulating layer 3 including the first cover insulating layer 15 and the second cover insulating layer 16 is formed in the second pattern portion 5.

[0060] (Effects of one embodiment) In the wired circuit board 1, the first wiring layer 7 of the wiring layer 6 includes a first wiring portion 8 and a second wiring portion 9. Therefore, the cross-sectional area can be increased, and the electrical resistance of the first wiring layer 7 can be reduced.

[0061] Furthermore, both end faces in the width direction of the second wiring portion 9 are disposed more inward in the width direction than both end faces of the first wiring portion 8. Therefore, at one end in the width direction of the first wiring layer 7, two one-side steps 17 can be formed by the first wiring portion 8 and the second wiring portion 9. At the other end in the width direction of the first wiring layer 7, two other-side steps 18 can be formed by the first wiring portion 8 and the second wiring portion 9. Therefore, the cover insulating layer 3 has an anchor effect of covering these steps, which can suppress peeling of the cover insulating layer 3 from the first wiring layer 7.

[0062] 10, if both end faces in the width direction of the second wiring portion 9 are located at the same positions as both end faces of the first wiring portion 8 and there is only one step 17 on one side and one step 18 on the other side, the anchor effect of the cover insulating layer 3 on the first wiring layer 7 is significantly reduced. Therefore, peeling of the cover insulating layer 3 from the first wiring layer 7 cannot be sufficiently suppressed.

[0063] Furthermore, in one embodiment of the wired circuit board 1, if the ratio (T2 / T1) of the thickness T2 of the second wiring portion 9 to the thickness T1 of the first wiring portion 8 is 0.9 or more and 2.0 or less, the cross-sectional area of ​​the first wiring layer 7 can be increased while reliably achieving the anchor effect, thereby more reliably suppressing peeling of the cover insulating layer 3 from the first wiring layer 7.

[0064] Furthermore, in this wired circuit board 1, the second wiring layer 10 and the third wiring layer 12 of the wiring layer 6 each include a third wiring portion 13 and a fourth wiring portion 14. Therefore, the second wiring layer 10 including the third wiring portion 13 and the third wiring layer 12 including the fourth wiring portion 14 can be used for a purpose different from that of the first wiring portion 8 and the second wiring portion 9, specifically, for signal wiring. Therefore, the wiring layer 6 can be used for a wide range of purposes.

[0065] Furthermore, in this wired circuit board 1, the wiring layer 6 includes a first wiring layer 7 (first pattern) and a second wiring layer 10 and a third wiring layer 12 (second pattern) that are independent of the first wiring layer 7, so that, for example, the first wiring layer 7 can be used as a power supply wiring, and the second wiring layer 10 and the third wiring layer 12 can be used as a signal wiring.

[0066] Furthermore, in this method, as shown in FIG. 3D, the second wiring portion 9 included in the first wiring layer 7 and the fourth wiring portion 14 included in the third wiring layer 12 are formed simultaneously, so that the second wiring portion 9 and the fourth wiring portion 14 included in different patterns can be easily formed at once.

[0067] (Variation) In the following modifications, the same components and steps as those in the above-described embodiment are denoted by the same reference numerals, and detailed descriptions thereof will be omitted. Furthermore, each modification can achieve the same effects as those in the above-described embodiment unless otherwise specified. Furthermore, the embodiment and its modifications can be combined as appropriate.

[0068] 4 to 7, the margin portion 19 may include an insulating cover layer 3. In these modified examples, the insulating cover layer 3 in the margin portion 19 is a first insulating cover layer 15. The first insulating cover layer 15 in the margin portion 19 connects the first insulating cover layer 15 of the first pattern portion 4 and the first insulating cover layer 15 of the second pattern portion 5 in the width direction.

[0069] 4, in the first pattern portion 4, the cover insulating layer 3 further includes a first cover insulating layer 15. That is, in the first pattern portion 4, the cover insulating layer 3 includes the first cover insulating layer 15 and the second cover insulating layer 16.

[0070] The first insulating cover layer 15 contacts a portion of the insulating base layer 2 near the outside of the first wiring portion 8 on one surface of the insulating base layer 2 in the thickness direction, and both end surfaces of the first wiring portion 8 in the width direction.

[0071] The second insulating cover layer 16 contacts one surface of the first wiring portion 8 in the thickness direction.

[0072] 5, the second insulating cover layer 16 contacts one thickness-wise side portion of both width-wise end faces of the second wiring portion 9. On the other hand, the first insulating cover layer 15 contacts the other thickness-wise side portion of both width-wise end faces of the second wiring portion 9.

[0073] 6, the second insulating cover layer 16 contacts all of both widthwise end faces of the second wiring portion 9 and a portion near the outside of the second wiring portion 9 on one thicknesswise surface of the first wiring portion 8. On the other hand, the first insulating cover layer 15 contacts both widthwise end portions of the second wiring portion 9 on one thicknesswise surface of the first wiring portion 8.

[0074] As shown in FIG. 7 , the eave portions 20 may be continuous with one thickness-direction side portions of both width-direction end faces of the second wiring portion 9. The eave portions 20 protrude outward in the width direction from one thickness-direction side portions of both width-direction end faces of the second wiring portion 9. The length between the end face of the eave portion 20 on one width-direction side and the end face of the eave portion 20 on the other width-direction side is, for example, the same as the width of the first wiring portion 8. In this modification, a groove 23 is formed between the eave portion 20 and the width-direction end portion of the first wiring portion 8. Note that the other thickness-direction side portions of both width-direction end faces of the second wiring portion 9 are positioned widthwise inward relative to both width-direction end faces of the first wiring portion 8, and the groove 23 is formed together with the eave portions 20 and both ends of the first wiring portion 8. The groove 23 is filled with the first cover insulating layer 15. Therefore, the cover insulating layer 3 can exhibit an anchor effect due to the groove 23.

[0075] As shown in FIGS. 8A and 8B, the wired circuit board 1 does not include the second pattern portion 5 but includes the first pattern portion 4.

[0076] The first pattern portion 4 has a front region 21 and a rear region 22 in that order toward the rear side.

[0077] The front cross section of the front region 21 is a cut surface along line XX in Figures 8A and 8B, and is the same as the left diagram of Figure 1B. As shown in the left diagram of Figure 1B, the first pattern portion 4 includes a base insulating layer 2, a first wiring portion 8, a second wiring portion 9, and a second cover insulating layer 16 in the front region 21.

[0078] 8A to 8B, and is the same as the right-hand view of Fig. 1B. As shown in the right-hand view of Fig. 1B, the first pattern portion 4 includes a base insulating layer 2, a third wiring portion 13, a first insulating cover layer 15, a fourth wiring portion 14, and a second insulating cover layer 16 in the rear region 22.

[0079] 8B, the first pattern portion 4 includes a fourth wiring layer 24 including the first wiring portion 8 and the third wiring portion 13, and a fifth wiring layer 25 including the second wiring portion 9 and the fourth wiring portion 14. The fourth wiring layer 24 and the fifth wiring layer 25 are electrically connected because the first wiring portion 8 and the second wiring portion 9 contact each other in the thickness direction in the front region 21.

[0080] In this wired circuit board 1, as shown in the left-hand diagram of Figure 1B, in the tip region 21, the above-mentioned two one-side steps 17 and two other-side steps 18 can prevent the cover insulating layer 3 from peeling off from the first wiring portion 8 and the second wiring portion 9.

[0081] 3E, the wired circuit board 1 can further include a metal support layer 29. The metal support layer 29 contacts one surface of the base insulating layer 2 in the thickness direction.

[0082] Another modified example of the method for producing a wired circuit board of the present invention will be described with reference to FIGS. 9A to 9E.

[0083] In one embodiment of the manufacturing method, as shown in FIG. 3D, the second wiring portion 9 is formed simultaneously with the fourth wiring portion 14, but in a modified example thereof, as shown in FIG. 9B, the second wiring portion 9 is formed simultaneously with the third wiring portion 13.

[0084] In this modification, first, the base insulating layer 2 is prepared as shown in Fig. 9A, followed by forming only the first wiring portion 8.

[0085] Next, as shown in FIG. 9B, the second wiring portion 9 and the third wiring portion 13 are formed simultaneously.

[0086] Next, as shown in FIG. 9C, the first insulating cover layer 15 is formed so as to cover the second wiring portion 9 and the third wiring portion 13.

[0087] Next, as shown in FIG. 9D, only the fourth wiring portion 14 is formed.

[0088] Thereafter, as shown in FIG. 9E, the second insulating cover layer 16 is formed so as to cover only the fourth wiring portion 14.

[0089] In the first pattern portion 4 of the wired circuit board 1 obtained by this method, the insulating cover layer 3 includes a first insulating cover layer 15.

[0090] Of the manufacturing method of this modified example and the manufacturing method of the first embodiment, the manufacturing method of the first embodiment is preferable.

[0091] In one embodiment of the manufacturing method, as shown in Fig. 3B, the first wiring portion 8 and the third wiring portion 13 are formed at the same time. Also, as shown in Fig. 3D, the second wiring portion 9 and the fourth wiring portion 14 are formed at the same time. Therefore, the wiring layer 6 can be formed in two steps (Figs. 3B and 3D).

[0092] In contrast, in the above-described modified example, the first wiring portion 8 is formed in the step of Fig. 9A, the second wiring portion 9 is formed in the step of Fig. 9B, and the fourth wiring portion 14 is formed in the step of Fig. 9D. Therefore, the wiring layer 6 is formed in three steps, that is, with more man-hours than in the first embodiment. [Explanation of symbols]

[0093] 1 Wiring circuit board 2 Base insulation layer 3 Cover insulation layer 4 First pattern section 5 Second pattern section 6 wiring layer 7 1st wiring layer 8 1st wiring section 9 2nd wiring section 10 2nd wiring layer 12 3rd wiring layer 13 Third wiring section 14 4th wiring section

Claims

1. A base insulating layer made of insulating resin; a wiring layer including a first wiring, the first wiring being arranged on one side of the base insulating layer in the thickness direction, the first wiring including a first wiring portion contacting one surface of the base insulating layer in the thickness direction and a second wiring portion contacting one surface of the first wiring portion in the thickness direction, and both end faces of the second wiring portion in a width direction perpendicular to the thickness direction and the transmission direction being arranged more inward than both end faces of the first wiring portion in the width direction; a first insulating cover layer made of insulating resin and in contact with the one surface of the base insulating layer in the thickness direction and with both end surfaces of the first wiring portion in the width direction; a second insulating cover layer made of insulating resin and in contact with one surface of the first insulating cover layer and one surface of the second wiring portion in the thickness direction; A wired circuit board comprising:

2. 2. The wired circuit board according to claim 1, wherein a ratio (T2 / T1) of a thickness T2 of said second wiring portion to a thickness T1 of said first wiring portion is 0.7 or more and 3.0 or less.

3. The wiring layer is a third wiring portion in contact with one surface of the insulating base layer in the thickness direction; a fourth wiring portion spaced apart from the third wiring portion on one side in the thickness direction; The wired circuit board according to claim 1 or 2, further comprising:

4. The wiring layer is a first pattern portion including the first wiring portion and the second wiring portion; a second pattern portion including the third wiring portion and the fourth wiring portion and independent of the first pattern portion; The wired circuit board according to claim 3, comprising:

5. 5. A method for producing a wired circuit board according to claim 4, forming the insulating base layer; forming the first wiring portion and the third wiring portion; forming the first insulating cover layer; simultaneously forming the second wiring portion and the fourth wiring portion; forming the second insulating cover layer; A method for manufacturing a wired circuit board, comprising:

6. A method for manufacturing a printed circuit board, The printed circuit board is a base insulating layer; a wiring layer disposed on one side of the base insulating layer in the thickness direction, the wiring layer comprising: a first wiring portion contacting one surface of the base insulating layer in the thickness direction; a second wiring portion contacting one surface of the first wiring portion in the thickness direction; a third wiring portion independent of the first wiring portion and contacting the one surface of the base insulating layer in the thickness direction; and a fourth wiring portion disposed on one side of the third wiring portion in the thickness direction and spaced apart, the wiring layer having both end faces of the second wiring portion in a width direction perpendicular to the thickness direction and the transmission direction disposed more inward than both end faces of the first wiring portion in the width direction; a first insulating cover layer that covers the first wiring portion, the second wiring portion, and the third wiring portion; a second insulating cover layer that covers the fourth wiring portion; Equipped with forming the insulating base layer; forming the first wiring portion; simultaneously forming the second wiring portion and the third wiring portion; forming the first insulating cover layer; forming the fourth wiring portion; forming the second insulating cover layer; A method for manufacturing a wired circuit board, comprising:

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