Printed wiring board and method for manufacturing printed wiring board

Abstract

To provide a printed wiring board having a relatively high wiring density and an excellent insulation property between wirings, and to provide a method of manufacturing the same.SOLUTION: A method for producing a laminate including a synthetic-resin film layer and an insulating film layer, the method comprising: a stacking step of stacking the insulating film on at least one surface side of the synthetic-resin film; and a vacuum hot-pressing step of vacuum hot-pressing a laminate in which the insulating film is stacked, wherein in the vacuum hot-pressing step, a heating temperature is 50 °C. or more and 150 °C. or less, a pressing time is 5 seconds or more and 20 seconds or less, and a pressing pressure is 0. 3MPa or more and 1. 3MPa or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a laminate. This application claims priority from Japanese Application No. 2016-201012, filed October 12, 2016, and incorporates by reference all of the contents of said Japanese application. [Background technology]

[0002] Printed wiring boards are widely used as electronic devices become smaller and lighter. These printed wiring boards generally have a structure in which a conductive pattern is formed on a base film whose main component is polyimide or the like, and these are further covered with an insulating layer such as solder resist (see JP 2013-004625 A). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-004625 Summary of the Invention

[0004] A printed wiring board according to one embodiment of the present invention comprises an insulating base film, a conductive pattern laminated on at least one side of the base film and including a plurality of wiring portions arranged in a row, and an insulating layer covering the outer surfaces of the base film and the conductive pattern, wherein the average spacing between the plurality of wiring portions is 1 μm or more and 20 μm or less, the average height is 30 μm or more and 120 μm or less, and the filling area ratio of the insulating layer between adjacent plurality of wiring portions in a cross-sectional view is 95% or more.

[0005] A method for manufacturing a printed wiring board according to one embodiment of the present invention includes a lamination step of laminating a conductive pattern including a plurality of wiring portions arranged in a row on at least one surface of an insulating base film, a lamination step of laminating an insulating film on the outer surfaces of the base film and the conductive pattern, and a vacuum hot pressing step of vacuum hot pressing the laminate with the insulating films laminated thereon, wherein the average spacing of the plurality of wiring portions is 1 μm or more and 20 μm or less and the average height is 30 μm or more and 120 μm or less. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic cross-sectional view of a printed wiring board according to one embodiment of the present invention. [Figure 2] FIG. 2 is a flow diagram showing a method for manufacturing a printed wiring board according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0007] [Problem to be solved by this disclosure] In recent years, the wiring density of printed wiring boards has been increasing due to the further miniaturization of electronic devices. As the wiring density increases, the wiring spacing (pitch) becomes extremely small. In conventional printed wiring boards, this can result in areas near the surface of the base film where the insulating layer is not filled between the wirings, resulting in insufficient insulation between the wirings.

[0008] The present invention has been made in view of the above circumstances, and has as its object to provide a printed wiring board having a relatively high wiring density and excellent insulation between wirings, and a method for manufacturing the same.

[0009] [Effects of this disclosure] The printed wiring board and the method for manufacturing the same of the present invention can improve both the wiring density and the insulation between the wirings.

[0010] [Description of the embodiment of the present invention] A printed wiring board according to one embodiment of the present invention comprises an insulating base film, a conductive pattern laminated on at least one side of the base film and including a plurality of wiring portions arranged in a row, and an insulating layer covering the outer surfaces of the base film and the conductive pattern, wherein the average spacing between the plurality of wiring portions is 1 μm or more and 20 μm or less, the average height is 30 μm or more and 120 μm or less, and the filling area ratio of the insulating layer between adjacent plurality of wiring portions in a cross-sectional view is 95% or more.

[0011] The printed wiring board has an average spacing and average height of the wiring portions within the above ranges, and has a relatively high wiring density, while the filling area ratio of the insulating layer between the wiring portions is 95% or more, so it also has excellent insulation. In other words, the printed wiring board has a relatively high wiring density and excellent insulation between the wiring portions.

[0012] The average minimum distance between the outer surface of the wiring portion and the outer surface of the insulating layer is preferably greater than 0 and not greater than 20 μm. By setting the average minimum distance between the wiring portion and the insulating layer within the above range, insulation can be maintained without increasing the thickness of the insulating layer, and therefore the thickness of the printed wiring board.

[0013] The insulating layer may be a solder resist. By using a solder resist as the insulating layer, the insulating layer can be easily and reliably filled at the above-mentioned filling area ratio.

[0014] In addition, a method for manufacturing a printed wiring board according to another embodiment of the present invention includes a lamination step of laminating a conductive pattern including a plurality of wiring portions arranged in a row on at least one surface of an insulating base film, a lamination step of laminating an insulating film on the outer surfaces of the base film and the conductive pattern, and a vacuum hot pressing step of vacuum hot pressing the laminate with the insulating films laminated thereon, wherein the average spacing of the plurality of wiring portions is 1 μm or more and 20 μm or less and the average height is 30 μm or more and 120 μm or less.

[0015] According to this method for manufacturing a printed wiring board, by laminating an insulating film onto the outer surface of a conductive pattern and then performing a vacuum hot press, the insulating layer can be easily and reliably filled between wiring portions having a relatively high wiring density, thereby producing a printed wiring board having a relatively high wiring density and excellent insulation properties.

[0016] The heating temperature in the vacuum hot pressing step is preferably 50° C. or higher and 150° C. or lower, and the pressing time is preferably 5 seconds or higher and 20 seconds or lower. By setting the pressing temperature and time in the vacuum hot pressing step within the above ranges, the insulating layer can be easily and reliably filled between the wiring portions.

[0017] The "filling area ratio" means the ratio of the filling area of ​​the insulating layer in a cross section perpendicular to the longitudinal direction of the wiring portion to the total area of ​​the region sandwiched between the side edges of adjacent wiring portions in a direction parallel to the surface of the printed wiring board.

[0018] [Details of the embodiment of the present invention] Hereinafter, one embodiment of a printed wiring board and a method for manufacturing the same according to the present invention will be described in detail with reference to the drawings. Note that the "front and back" of the printed wiring board of this embodiment refer to the direction in the thickness direction of the printed wiring board, with the conductive pattern laminated side being the "front" and the opposite side to the conductive pattern laminated side being the "back", and do not refer to the front and back in the state in which the printed wiring board is used.

[0019] [Printed wiring board] The printed wiring board shown in Figure 1 mainly comprises an insulating base film 1, a conductive pattern 2 laminated on one side (front side) of the base film 1, and an insulating layer 3 covering the outer surfaces of the base film 1 and the conductive pattern 2.

[0020] <Base film> The base film 1 is a layer made of an electrically insulating synthetic resin. The base film 1 also serves as a substrate for forming the conductive pattern 2. The base film 1 may be flexible, in which case the printed wiring board is used as a flexible printed wiring board.

[0021] The material of the base film 1 is not particularly limited as long as it has insulating properties, but a low-dielectric-constant synthetic resin film formed into a sheet shape can be used. Examples of the main component of this synthetic resin film include polyimide, polyethylene terephthalate, liquid crystal polymer, and fluororesin. The "main component" refers to the component with the highest content, for example, the component that accounts for 50% by mass or more of the material.

[0022] The lower limit of the average thickness of the base film 1 is preferably 5 μm, more preferably 10 μm. The upper limit of the average thickness of the base film 1 is preferably 50 μm, more preferably 40 μm. If the average thickness of the base film 1 is less than the lower limit, the insulating strength of the base film 1 may be insufficient. On the other hand, if the average thickness of the base film 1 exceeds the upper limit, the printed wiring board may become unnecessarily thick.

[0023] <Conductive pattern> The conductive pattern 2 is a layer made of a conductive material and includes a plurality of wiring portions 2a arranged in a row. The wiring portions 2a are, for example, wiring that forms a coil pattern. The conductive pattern 2 may also include patterns other than the wiring portions 2a, such as land portions. The conductive pattern 2 may be laminated directly on the surface of the base film 1, or may be laminated via an adhesive layer.

[0024] The material (main component) of the conductive pattern 2 is not particularly limited as long as it is conductive, but a material with low electrical resistance is preferable. The conductive pattern 2 can be formed of, for example, copper, silver, etc. Alternatively, the conductive pattern 2 may be plated with gold, silver, tin, nickel, etc.

[0025] The lower limit of the average spacing d1 between the multiple wiring portions 2a is 1 μm, more preferably 3 μm, and even more preferably 5 μm. On the other hand, the upper limit of the average spacing d1 between the multiple wiring portions 2a is 20 μm, more preferably 15 μm, and even more preferably 10 μm. If the average spacing d1 between the multiple wiring portions 2a is smaller than the lower limit, there is a risk of short-circuiting between the wiring portions 2a. Conversely, if the average spacing d1 between the multiple wiring portions 2a exceeds the upper limit, there is a risk that the required wiring density will not be met. Furthermore, since an insulating layer can easily be filled between the wiring portions 2a using conventional methods, there is a risk that the effects of the present invention will not be fully realized. The "average spacing between the multiple wiring portions" refers to the minimum distance between the opposing side edges of adjacent wiring portions in a cross section perpendicular to the longitudinal direction of the wiring portions, averaged in the longitudinal direction of the wiring portions.

[0026] The lower limit of the average height h of the multiple wiring portions 2a is 30 μm, more preferably 35 μm, and even more preferably 40 μm. On the other hand, the upper limit of the average height h of the multiple wiring portions 2a is 120 μm, more preferably 100 μm, and even more preferably 80 μm. If the average height h of the multiple wiring portions 2a is smaller than the above lower limit, the resistance of the wiring portions 2a may become excessively high as the wiring density increases. Furthermore, since insulating layers can easily be filled between the wiring portions 2a even with conventional methods, the effects of the present invention may not be fully achieved. Conversely, if the average height h of the multiple wiring portions 2a exceeds the above upper limit, the printed wiring board may become unnecessarily thick. The "average height of the multiple wiring portions" refers to the maximum height of the wiring portions in a cross section perpendicular to the longitudinal direction of the wiring portions, averaged along the longitudinal direction of the wiring portions.

[0027] The lower limit of the average width of the multiple wiring portions 2a is preferably 10 μm, more preferably 15 μm, and even more preferably 20 μm. On the other hand, the upper limit of the average width of the multiple wiring portions 2a is preferably 40 μm, more preferably 35 μm, and even more preferably 30 μm. If the average width of the multiple wiring portions 2a is smaller than the above lower limit, manufacturing may be difficult. Conversely, if the average width of the multiple wiring portions 2a exceeds the above upper limit, the required wiring density may not be met. Note that the "average width of the multiple wiring portions" refers to the width of the bottom surface (interface with the base film) of the wiring portions in a cross section perpendicular to the longitudinal direction of the wiring portions, averaged in the longitudinal direction of the wiring portions.

[0028] The lower limit of the average aspect ratio of the multiple wiring portions 2a is preferably 1.2, more preferably 1.4, and even more preferably 1.6. On the other hand, the upper limit of the average aspect ratio of the multiple wiring portions 2a is preferably 5.0, more preferably 4.0, and even more preferably 3.0. If the average aspect ratio of the multiple wiring portions 2a is smaller than the above lower limit, the required wiring density may not be met. Conversely, if the average aspect ratio of the multiple wiring portions 2a exceeds the above upper limit, manufacturing may become difficult. Note that the "aspect ratio of the multiple wiring portions" is the ratio of the average height h to the average width.

[0029] The lower limit of the ratio (h / d1) of the average height h to the average spacing d1 of the multiple wiring portions 2a is preferably 2.0, more preferably 3.0, and even more preferably 4.0. On the other hand, the upper limit of the ratio (h / d1) is preferably 12.0, more preferably 10.0, and even more preferably 8.0. If the ratio (h / d1) is smaller than the lower limit, the required wiring density may not be met. Conversely, if the ratio (h / d1) exceeds the upper limit, the printed wiring board may become unnecessarily thick.

[0030] In addition, in the wiring portions 2a forming the coil pattern, it is preferable that the cross-sectional areas (average width, average height, and average aspect ratio) of the plurality of wiring portions 2a are equal to each other.

[0031] As shown in Figure 1, the wiring portion 2a has a tapered portion on the bottom surface on the side of the base film 1, the width of which gradually decreases toward the base film 1. This tapered portion is formed by secondary plating when the wiring portion 2a is formed by further secondary plating on a pattern formed by the semi-additive method. In such wiring portion 2a, it is difficult to fill the insulating layer, particularly in the tapered portion, and voids are likely to form.

[0032] <Insulating layer> The insulating layer 3 is a layer in the printed wiring board that mainly protects the conductive pattern 2. The material of the insulating layer 3 is not particularly limited as long as it has insulating properties, and materials containing resins such as polyimide, epoxy resin, phenolic resin, acrylic resin, polyester, thermoplastic polyimide, polyethylene terephthalate, fluororesin, and liquid crystal polymer as the main component can be used. Among these, thermoplastic resins are preferred. In particular, by using a solder resist as the insulating layer 3, the insulating layer 3 can be easily formed by the manufacturing method described below. Furthermore, the insulating layer 3 is preferably formed by laminating a resin film.

[0033] The lower limit of the melting point or glass transition point in the absence of a melting point (hereinafter also referred to as the "melting point or glass transition point T") of the resin that is the main component of the insulating layer 3 is preferably 30°C, more preferably 40°C, and even more preferably 50°C. On the other hand, the upper limit of the melting point or glass transition point T is preferably 200°C, more preferably 190°C, and even more preferably 180°C. If the melting point or glass transition point T is lower than the above lower limit, the heat resistance of the insulating layer 3 may be insufficient. On the other hand, if the melting point or glass transition point T exceeds the above upper limit, it may be difficult to achieve the filling area ratio described below. Note that the "melting point" refers to the melting point peak measured by a differential scanning calorimeter (DSC) in accordance with JIS-K-7121 (2012), and the "glass transition point" refers to the midpoint glass transition temperature measured by a differential scanning calorimeter (DSC) in accordance with JIS-K-7121 (2012).

[0034] The lower limit of the filling area ratio of the insulating layer 3 between adjacent wiring portions 2a in a cross-sectional view is 95%, more preferably 98%, and even more preferably 99%. Furthermore, it is preferable that the filling area ratio is 100%, that is, that there are substantially no voids (air bubbles) between the insulating layer 3 and the base film 1.

[0035] The lower limit of the average thickness of the insulating layer 3 (the average distance from the surface of the base film 1 to the outer surface of the insulating layer 3) is preferably 40 μm, more preferably 50 μm, and even more preferably 60 μm. On the other hand, the upper limit of the average thickness of the insulating layer 3 is preferably 90 μm, more preferably 80 μm, and even more preferably 70 μm. If the average thickness of the insulating layer 3 is less than the above lower limit, the insulating properties may be insufficient. Conversely, if the average thickness of the insulating layer 3 exceeds the above upper limit, the printed wiring board may become unnecessarily thick.

[0036] The average minimum distance d2 between the outer surface of the wiring portion 2a and the outer surface of the insulating layer 3 may be greater than 0. However, the lower limit of the average minimum distance d2 is preferably 0.1 μm, more preferably 0.5 μm, and even more preferably 1 μm. On the other hand, the upper limit of the average minimum distance d2 is preferably 20 μm, more preferably 15 μm, and even more preferably 10 μm. If the average minimum distance d2 is smaller than the lower limit, the insulation may be insufficient. Conversely, if the average minimum distance d2 exceeds the upper limit, the printed wiring board may become unnecessarily thick. In other words, by setting the average minimum distance d2 within the above range, the overall thickness of the printed wiring board can be reduced while maintaining the insulation provided by the insulating layer 3. The "average minimum distance between the outer surface of the wiring portion and the outer surface of the insulating layer" refers to the minimum distance between the surface of the wiring portion opposite the base film and the outer surface of the insulating layer, averaged along the longitudinal direction of the wiring portion.

[0037] [Printed wiring board manufacturing method] As shown in Figure 2, the method for manufacturing the printed wiring board mainly includes a lamination process S1 in which a conductive pattern including a plurality of wiring portions arranged in a row is laminated on at least one surface of an insulating base film, a lamination process S2 in which an insulating film is laminated on the outer surfaces of the base film and the conductive pattern, and a vacuum heat pressing process S3 in which the laminate with the insulating film laminated thereon is vacuum heat pressed.

[0038] <Lamination process> In the lamination step S1, a conductive pattern including a plurality of wiring portions arranged in a row is laminated on at least one surface of the base film. A known method for laminating the conductive pattern can be used, such as a subtractive method or a semi-additive method. In particular, by using the semi-additive method, a conductive pattern with a high wiring density can be efficiently obtained.

[0039] <Layering process> In the overlaying step S2, an insulating film that forms an insulating layer is overlaid on the outer surface of the laminate of the base film and conductive pattern obtained in the lamination step S1. The main component of this insulating film can be the same as the main component of the insulating layer of the printed wiring board. In addition, it is preferable that this insulating film be flexible.

[0040] The average thickness of the insulating film is appropriately designed depending on the thickness of the conductive pattern and the thickness of the insulating layer to be formed, and the lower limit thereof is preferably 30 μm, more preferably 40 μm, while the upper limit thereof is preferably 80 μm, more preferably 60 μm.

[0041] <Vacuum heat pressing process> In the vacuum hot pressing step S3, the laminate of the base film and the conductive pattern obtained in the overlapping step S2, on which the insulating film is superimposed, is vacuum hot pressed. This vacuum hot pressing can be performed using a known pressing device, and is performed batchwise on the continuous sheet-like laminate.

[0042] The lower limit of the heating temperature in the vacuum hot press is preferably 50°C, more preferably 60°C, and even more preferably 70°C. On the other hand, the upper limit of the heating temperature is preferably 150°C, more preferably 130°C, and even more preferably 110°C.

[0043] The lower limit of the heating time in the vacuum hot press is preferably 5 seconds, more preferably 8 seconds, while the upper limit of the heating time is preferably 20 seconds, more preferably 15 seconds.

[0044] If the heating temperature or heating time is lower than the lower limit, the insulating layer may not sufficiently fill the spaces between the wiring portions, resulting in a decrease in insulating properties. Conversely, if the heating temperature or heating time exceeds the upper limit, the base film or the like may be deformed or deteriorated.

[0045] The lower limit of the pressure in the vacuum hot press is preferably 0.3 MPa, more preferably 0.4 MPa, and even more preferably 0.5 MPa. On the other hand, the upper limit of the pressure is preferably 1.3 MPa, more preferably 1.2 MPa, and even more preferably 1.1 MPa. If the pressure is lower than the lower limit, the insulating layer may not be sufficiently filled between the wiring portions, resulting in a decrease in insulation properties. Conversely, if the pressure exceeds the upper limit, the base film or the like may be deformed or damaged.

[0046] After the vacuum hot pressing step S3, a step of forming openings for electrical connection in the insulating layer may be performed. When a dry film of solder resist is used as the insulating film, the openings can be easily formed by steps such as exposure and development.

[0047] <Advantages> The printed wiring board has an average spacing and average height of wiring portions within the above ranges, and has a relatively high wiring density, while the filling area ratio of the insulating layer between the wiring portions is 95% or more, so it also has excellent insulation. In other words, the printed wiring board has a relatively high wiring density and excellent insulation between the wiring portions. Furthermore, the manufacturing method for the printed wiring board makes it relatively easy to obtain such a printed wiring board compared to when an insulating layer is formed by applying an insulating ink.

[0048] The printed wiring board can be used favorably as an actuator, an antenna, a transformer, etc. for small devices because the wiring density can be increased.

[0049] [Other embodiments] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is not limited to the configurations of the above-described embodiments, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0050] In the above embodiment, a printed wiring board having a single base film and one layer of conductive pattern laminated on one side of the base film has been described, but a single base film having conductive patterns laminated on both sides is also within the intended scope of the present invention. Furthermore, the printed wiring board may be a multilayer printed wiring board having multiple base films, each of which has a conductive pattern on one or both sides.

[0051] The insulating layer of the printed wiring board may be formed by coating and drying a resin composition (insulating ink).

[0052] [Note] (Section 1) an insulating base film; a conductive pattern laminated on at least one surface of the base film and including a plurality of wiring portions arranged in a row; an insulating layer covering the outer surfaces of the base film and the conductive pattern; Equipped with The average interval between the plurality of wiring portions is 1 μm or more and 20 μm or less, and the average height is 30 μm or more and 120 μm or less, A printed wiring board in which the filling area ratio of the insulating layer between the adjacent wiring portions is 95% or more in a cross-sectional view. (Section 2) Item 2. The printed wiring board according to item 1, wherein the average minimum distance between the outer surface of the wiring portion and the outer surface of the insulating layer is greater than 0 and 20 μm or less. (Section 3) 3. The printed wiring board according to item 1 or 2, wherein the plurality of wiring portions have a tapered portion on a bottom surface portion on the base film side, the width of which gradually decreases toward the base film side. (Section 4) 4. The printed wiring board according to item 1, 2 or 3, wherein the average interval between the plurality of wiring portions is 1 μm or more and less than 10 μm. (Section 5) 5. The printed wiring board according to any one of items 1 to 4, wherein the average width of the plurality of wiring portions is 10 μm or more and 40 μm or less. (Section 6) 6. The printed wiring board according to any one of items 1 to 5, wherein the ratio (h / d1) of the average height h of the plurality of wiring portions to the average spacing d1 is 2.0 or more and 12.0 or less. (Section 7) 7. The printed wiring board according to any one of items 1 to 6, wherein the insulating layer is a solder resist. (Section 8) a lamination step of laminating a conductive pattern including a plurality of wiring portions arranged in a row on at least one surface side of an insulating base film; a laminating step of laminating an insulating film on the outer surfaces of the base film and the conductive pattern; a vacuum hot pressing step of vacuum hot pressing the laminate obtained by overlapping the insulating films at a pressing pressure of 0.3 MPa or more and 1.3 MPa or less and a heating temperature of 50°C or more and 150°C or less, A method for manufacturing a printed wiring board, wherein the average interval between the plurality of wiring portions is 1 μm or more and 20 μm or less, and the average height is 30 μm or more and 120 μm or less. (Section 9) 9. The method for producing a printed wiring board according to item 8, wherein the pressure application time in the vacuum hot pressing step is 5 seconds or more and 20 seconds or less. (Section 10) 10. The method for manufacturing a printed wiring board according to item 8 or 9, wherein the plurality of wiring portions have a tapered portion on the bottom surface on the base film side, the width of which gradually decreases towards the base film side. (Section 11) Item 11. The method for producing a printed wiring board according to item 8, 9 or 10, wherein the average interval between the plurality of wiring portions is 1 μm or more and less than 10 μm. (Section 12) 12. The method for producing a printed wiring board according to any one of items 8 to 11, wherein the average width of the plurality of wiring portions is 10 μm or more and 40 μm or less. (Section 13) 13. The method for manufacturing a printed wiring board according to any one of items 8 to 12, wherein the ratio (h / d1) of the average height h to the average spacing d1 of the plurality of wiring portions is 2.0 or more and 12.0 or less. [Explanation of symbols]

[0053] 1 base film 2 Conductive pattern 2a Wiring section 3. Insulation layer S1 Lamination process S2 Layering process S3 Vacuum heat pressing process

Claims

1. an insulating and flexible base film; a conductive pattern laminated on at least one surface of the base film and including a plurality of wiring portions arranged in a row; an insulating layer covering the outer surfaces of the base film and the conductive pattern; Equipped with the average interval between the plurality of wiring portions is 1 μm or more and 20 μm or less, and the average height is 30 μm or more and 120 μm or less; A printed wiring board in which the filling area ratio of the insulating layer between the adjacent wiring portions in a cross-sectional view is 95% or more.

2. 2. The printed wiring board according to claim 1, wherein the average minimum distance between the outer surface of the wiring portion and the outer surface of the insulating layer is greater than 0 and not greater than 20 [mu]m.

3. 3. The printed wiring board according to claim 1, wherein the plurality of wiring portions have a tapered portion at a bottom surface thereof on the side of the base film, the width of which gradually decreases toward the base film.

4. 4. The printed wiring board according to claim 1, wherein the average interval between the plurality of wiring portions is 1 μm or more and less than 10 μm.

5. 5. The printed wiring board according to claim 1, wherein the average width of the plurality of wiring portions is 10 [mu]m or more and 40 [mu]m or less.

6. 6. The printed wiring board according to claim 1, wherein a ratio (h / d1) of an average height h of the plurality of wiring portions to an average spacing d1 between the wiring portions is 2.0 or more and 12.0 or less.

7. 7. The printed wiring board according to claim 1, wherein the insulating layer is a solder resist.

8. a lamination step of laminating a conductive pattern including a plurality of wiring portions arranged in a row on at least one surface side of an insulating and flexible base film; a laminating step of laminating an insulating film on the outer surfaces of the base film and the conductive pattern; a vacuum hot pressing step of vacuum hot pressing the laminate obtained by overlapping the insulating films at a pressing pressure of 0.3 MPa or more and 1.3 MPa or less and a heating temperature of 50°C or more and 150°C or less to fill an insulating layer between the plurality of wiring portions, the average interval between the plurality of wiring portions is 1 μm or more and 20 μm or less, and the average height is 30 μm or more and 120 μm or less; A method for manufacturing a printed wiring board, wherein the insulating layer fills an area ratio of 95% or more between the plurality of adjacent wiring portions in a cross-sectional view.

9. 9. The method for producing a printed wiring board according to claim 8, wherein the pressure application time in the vacuum hot pressing step is 5 seconds or more and 20 seconds or less.

10. 10. The method for manufacturing a printed wiring board according to claim 8, wherein the plurality of wiring portions have, at the bottom surface portion on the side of the base film, a tapered portion whose width gradually decreases toward the base film.

11. 11. The method for manufacturing a printed wiring board according to claim 8, 9 or 10, wherein the average interval between the plurality of wiring portions is 1 μm or more and less than 10 μm.

12. The method for manufacturing a printed wiring board according to any one of claims 8 to 11, wherein the average width of the plurality of wiring portions is 10 µm or more and 40 µm or less.

13. 13. The method for manufacturing a printed wiring board according to claim 8, wherein a ratio (h / d1) of the average height h of the plurality of wiring portions to the average spacing d1 between the wiring portions is 2.0 or more and 12.0 or less.

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