printed wiring board

Abstract

To provide a print circuit board capable of securing a connection area of a terminal part of a conductive pattern.SOLUTION: A print circuit board comprises: a base film that includes a principal surface; a conductive pattern that is arranged onto the principal surface; and a coverlay that includes an adhesive layer arranged onto the principal surface so as to cover the conductive pattern, and an insulator film arranged onto the adhesive layer. The conductive pattern includes a terminal part. In the coverlay, an opening part making an upper surface of the terminal part to be exposed by penetrating the coverlay is formed. When an edge of the opening part in a lower surface of the adhesive layer and an edge of the opening part in a lower surface of the insulator film are a first opening edge and a second opening edge respectively, a resin flow width that is a distance between the first opening edge and the second opening edge is 30% or less with respect to a minimum value of a width of the first opening edge.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to printed wiring boards. [Background technology]

[0002] For example, International Publication No. 2016 / 147993 (Patent Document 1) describes a printed wiring board. The printed wiring board has a base film, a conductive pattern, and an insulating layer. The base film has a main surface. The conductive pattern is disposed on the main surface of the base film. The conductive pattern has a plurality of wiring portions arranged in a direction perpendicular to the normal to the main surface of the base film. The insulating layer is disposed on the main surface of the base film so as to cover the conductive pattern. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2016 / 147993 Summary of the Invention

[0004] The printed wiring board of the present disclosure includes a base film having a principal surface, a conductive pattern disposed on the principal surface, and a coverlay having an adhesive layer disposed on the principal surface so as to cover the conductive pattern and an insulating film disposed on the adhesive layer. The conductive pattern has a terminal portion. The coverlay has an opening formed therein that penetrates the coverlay and exposes an upper surface of the terminal portion. If the edge of the opening on the lower surface of the adhesive layer and the edge of the opening on the lower surface of the insulating film are defined as a first opening edge and a second opening edge, respectively, the resin flow width, which is the distance between the first opening edge and the second opening edge, is 30 percent or less of the minimum width of the first opening edge. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a plan view of a printed wiring board 100. FIG. [Figure 2] FIG. 2 is a bottom view of printed wiring board 100. FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 5 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 7 is a diagram showing the manufacturing process of the printed wiring board 100. [Figure 8] FIG. 8 is a cross-sectional view of a printed wiring board 100 according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0006] [Problem to be solved by this disclosure] The insulating layer may be, for example, a coverlay. The coverlay has an adhesive layer disposed on the main surface of the base film so as to cover the conductive pattern, and an insulating film disposed on the adhesive layer. To electrically connect the conductive pattern to the outside, the coverlay has openings formed therein that expose the upper surfaces of the terminal portions of the conductive pattern.

[0007] The edge of the opening on the underside of the adhesive layer is referred to as the first opening edge, and the edge of the opening on the underside of the insulating film is referred to as the second opening edge. When attaching the coverlay to the base film, a phenomenon (resin flow) in which the adhesive layer flows may occur so that the first opening edge is positioned more inward than the second opening edge in a plan view. If the distance between the first opening edge and the second opening edge (resin flow width) becomes too large as a result of the resin flow, the area of ​​the top surface of the conductive pattern used for electrical connection to the outside becomes too small.

[0008] The present disclosure has been made in view of the above-described problems of the conventional art. More specifically, the present disclosure provides a printed wiring board capable of ensuring a connection area for terminal portions of a conductive pattern.

[0009] [Effects of this disclosure] According to the printed wiring board of the present disclosure, it is possible to ensure a sufficient connection area for the terminal portion.

[0010] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described.

[0011] (1) A printed wiring board according to an embodiment includes a base film having a main surface, a conductive pattern disposed on the main surface, and a coverlay having an adhesive layer disposed on the main surface so as to cover the conductive pattern and an insulating film disposed on the adhesive layer. The conductive pattern has a terminal portion. The coverlay has an opening formed therein that penetrates the coverlay and exposes the upper surface of the terminal portion. If the edge of the opening on the lower surface of the adhesive layer and the edge of the opening on the lower surface of the insulating film are defined as a first opening edge and a second opening edge, respectively, the resin flow width, which is the distance between the first opening edge and the second opening edge, is 30 percent or less of the minimum width of the first opening edge. The printed wiring board of (1) above makes it possible to ensure a connection area for the terminal portion.

[0012] (2) In the printed wiring board of (1) above, the resin flow width may be 0 mm or more and 0.3 mm or less.

[0013] (3) In the printed wiring board of (1) above, the insulating film may have a thickness of 2 μm or more and 7 μm or less. The printed wiring board of (3) above makes it possible to further ensure the connection area of ​​the terminal portion.

[0014] (4) In the printed wiring board of (1) above, the thickness of the adhesive layer between the upper surface of the conductive pattern and the lower surface of the insulating film may be 3 μm or more and 15 μm or less. The printed wiring board of (4) above makes it possible to ensure the connection area of ​​the terminal portion while ensuring adhesion between the adhesive layer and the insulating film.

[0015] (5) In the printed wiring board of (1) above, the thickness of the conductive pattern may be 30 μm or more and 150 μm or less. With the printed wiring board of (5) above, it is possible to ensure the connection area of ​​the terminal portion even in cases where resin flow is likely to occur.

[0016] (6) In the printed wiring board of (1) above, the conductive pattern may have a plurality of wiring portions. The normal to the main surface may be along a first direction. Each of the plurality of wiring portions may be along a second direction perpendicular to the first direction. The plurality of wiring portions may be arranged along a third direction perpendicular to the first and second directions. The distance between two adjacent ones of the plurality of wiring portions may be 3 μm or more and 30 μm or less. According to the printed wiring board of (6) above, it is possible to ensure the connection area of ​​the terminal portion even in cases where resin flow is likely to occur.

[0017] (7) In the printed wiring board of (1) above, the arithmetic mean height of the irregularities on the upper surface of the insulating film may be 0.010 μm or more and 1.00 μm or less.

[0018] (8) In the printed wiring board of (1) above, the conductive pattern may have a plurality of wiring portions. A normal to the main surface may be along a first direction. Each of the plurality of wiring portions may be along a second direction perpendicular to the first direction. The plurality of wiring portions may be arranged along a third direction perpendicular to the first and second directions. The period of the concave-convex pattern on the upper surface of the insulating film may be 0.80 to 1.20 times the pitch between two adjacent ones of the plurality of wiring portions in a portion of the insulating film above the plurality of wiring portions.

[0019] (9) In the printed wiring boards of (1) to (9) above, the insulating film may be made of polyimide or liquid crystal polymer.

[0020] [Details of the embodiments of the present disclosure] Next, details of an embodiment of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and redundant description will not be repeated. A printed wiring board according to the embodiment is referred to as a printed wiring board 100.

[0021] (Configuration of printed wiring board 100) The configuration of the printed wiring board 100 will be described below.

[0022] FIG. 1 is a plan view of printed wiring board 100. FIG. 2 is a bottom view of printed wiring board 100. FIG. 2 shows printed wiring board 100 as viewed from the opposite side to that of FIG. 1. Coverlays 31 and 32 are omitted from FIGS. 1 and 2. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 1. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 1. FIG. 5 is a cross-sectional view taken along line VV in FIG. 1. FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 1. As shown in FIGS. 1 to 6, printed wiring board 100 has a base film 10, conductive patterns 21 and 22, and coverlays 31 and 32.

[0023] The base film 10 has a main surface 10a and a main surface 10b. The main surface 10a and the main surface 10b are end surfaces of the base film 10 in the thickness direction. The main surface 10b is the surface opposite to the main surface 10a. The base film 10 is made of a flexible, electrically insulating material. The base film 10 is made of, for example, polyimide or a liquid crystal polymer. The normal direction of the main surface 10a (main surface 10b) is defined as a first direction DR1.

[0024] The conductive pattern 21 is disposed on the main surface 10a. The conductive pattern 21 is wound in a spiral shape in a plan view. The conductive pattern 21 has a plurality of wiring portions 21a.

[0025] The multiple wiring portions 21a may be multiple straight line portions 21b or multiple curved line portions 21c. The straight line portions 21b extend linearly in a plan view. The curved line portions 21c extend curvedly in a plan view. The extension direction of the wiring portions 21a (straight line portions 21b, curved line portions 21c) is defined as the second direction DR2. Note that when the wiring portions 21a are curved line portions 21c, the second direction DR2 is the tangent direction of the curved line portions 21c.

[0026] The wiring portions 21a (straight portions 21b and curved portions 21c) are arranged at intervals along the third direction DR3, which is perpendicular to the first direction DR1 and the second direction DR2.

[0027] The conductive pattern 22 is disposed on the main surface 10b. The conductive pattern 22 is wound in a spiral shape in a plan view. The conductive pattern 22 has a plurality of wiring portions 22a.

[0028] The multiple wiring portions 22a may be multiple straight portions 22b or multiple curved portions 22c. The straight portion 22b extends linearly in a plan view. The curved portion 22c extends curvedly in a plan view. The wiring portions 22a (straight portion 22b, curved portion 22c) extend along the second direction DR2. When the wiring portion 22a is the curved portion 22c, the second direction DR2 is the tangential direction of the curved portion 22c. The multiple wiring portions 22a (straight portion 22b, curved portion 22c) are arranged at intervals along the third direction DR3.

[0029] The conductive pattern 21 has a land 21d at one end and a land 21e at the other end. The lands 21d and 21e are located at the outermost and innermost peripheries of the conductive pattern 21, respectively. The conductive pattern 22 has a land 22d at one end and a land 22e at the other end. The lands 22d and 22e are located at the innermost and outermost peripheries of the conductive pattern 22, respectively. The lands 21d and 22e are terminal portions used for electrical connection to the outside. The lands 21e and 22d overlap each other in a plan view.

[0030] Each of the conductive patterns 21 and 22 is formed by, for example, a semi-additive method. More specifically, each of the conductive patterns 21 and 22 has a seed layer 23, an electroless plating layer 24, and an electrolytic plating layer 25. However, each of the conductive patterns 21 and 22 may also be formed by a subtractive method.

[0031] The seed layer 23 is disposed on the main surfaces (main surfaces 10a and 10b) of the base film 10. The seed layer 23 is, for example, a sputtered layer (a layer formed by sputtering). The seed layer 23 has, for example, a first layer and a second layer. The first layer is disposed on the main surfaces (main surfaces 10a and 10b) of the base film 10. The second layer is disposed on the first layer. The first layer and the second layer are formed, for example, from a nickel-chromium alloy and copper, respectively.

[0032] Electroless plated layer 24 is a layer formed by electroless plating. Electroless plated layer 24 is disposed on seed layer 23. Electroless plated layer 24 is formed of, for example, copper. Electrolytic plated layer 25 is a layer formed by electrolytic plating. Electrolytic plated layer 25 is disposed on electroless plated layer 24. Electrolytic plated layer 25 is formed of, for example, copper.

[0033] Although not shown, a through hole 10c is formed in the base film 10. The through hole 10c penetrates the base film 10 in the thickness direction. In a plan view, the through hole 10c overlaps the land 21e and the land 22d. The electroless plating layer 24 is also disposed on the inner wall surface of the through hole 10c. The electrolytic plating layer 25 is also embedded in the through hole 10c. This electrically connects the conductive pattern 21 and the conductive pattern 22 to each other. When a voltage is applied between the land 21d and the land 22e, a current flows in a spiral shape in the conductive pattern 21 and the conductive pattern 22, and this current generates a magnetic field. From another perspective, the printed wiring board 100 is a coil device.

[0034] The thickness of the conductive pattern 21 is defined as thickness T1. The thickness of the conductive pattern 22 is defined as thickness T2. Thicknesses T1 and T2 are, for example, not less than 30 μm and not more than 150 μm. The distance between two adjacent wiring portions 21a is defined as distance DIS1. The distance between two adjacent wiring portions 22a is defined as distance DIS2. Distances DIS1 and DIS2 are, for example, not less than 3 μm and not more than 30 μm.

[0035] Each of the coverlays 31 and 32 has an adhesive layer 33 and an insulating film 34. The adhesive layer 33 is a layer formed from an adhesive. The adhesive layer 33 of the coverlay 31 is disposed on the main surface 10a so as to cover the conductive pattern 21. The adhesive layer 33 of the coverlay 32 is disposed on the main surface 10b so as to cover the conductive pattern 22. The insulating film 34 is disposed on the adhesive layer 33. The insulating film 34 is formed from, for example, polyimide or a liquid crystal polymer.

[0036] The thickness of the adhesive layer 33 of the coverlay 31 between the upper surface of the conductive pattern 21 and the lower surface of the insulating film 34 of the coverlay 31 is defined as thickness T3. The thickness of the adhesive layer 33 of the coverlay 32 between the upper surface of the conductive pattern 22 and the lower surface of the insulating film 34 of the coverlay 32 is defined as thickness T4. Thicknesses T3 and T4 are, for example, not less than 3 μm and not more than 15 μm.

[0037] The thickness of the insulating film 34 of the coverlay 31 is defined as thickness T5. The thickness of the insulating film 34 of the coverlay 32 is defined as thickness T6. The thicknesses T5 and T6 are, for example, not less than 2 μm and not more than 7 μm.

[0038] The arithmetic mean height (Sa) of the irregularities on the upper surface of the insulating film 34 is 0.010 μm or more and 1.00 μm or less. The arithmetic mean height of the irregularities on the upper surface of the insulating film 34 is measured using a laser microscope. The definition of the arithmetic mean height is as specified in ISO25178.

[0039] The upper surface of the insulating film 34 has projections and recesses along the third direction DR3. The pitch between two adjacent wiring portions 21a is defined as pitch P1. The pitch between two adjacent wiring portions 22a is defined as pitch P2. The period of the projections and recesses on the upper surface of the insulating film 34 in the third direction DR3 is, for example, 0.80 to 1.20 times the pitch P1 on the portions of the insulating film 34 that are above the multiple wiring portions 21a. The period of the projections and recesses on the upper surface of the insulating film 34 in the third direction DR3 is, for example, 0.80 to 1.20 times the pitch P2 on the portions of the insulating film 34 that are above the multiple wiring portions 22a.

[0040] The period of the unevenness on the top surface of the insulating film 34 in the third direction DR3 is obtained by measuring the top surface of the insulating film 34 using a laser microscope at a magnification of 20x or more and 50x or less, and measuring the distance between two adjacent convex portions.

[0041] An opening 35 is formed in the coverlay 31. The opening 35 penetrates the coverlay 31 (adhesive layer 33 and insulating film 34) in the thickness direction. The upper surface of the land 21d is exposed from the opening 35. An opening 36 is formed in the coverlay 32. The opening 36 penetrates the coverlay 32 (adhesive layer 33 and insulating film 34) in the thickness direction. The upper surface of the land 22e is exposed from the opening 36.

[0042] The width of opening 35 in insulating film 34 and the width of opening 36 in insulating film 34 are defined as width W1 and width W2, respectively. Width W1 and width W2 are measured on the underside of insulating film 34. Distance DIS3 is the distance between the edge of opening 35 on the underside of adhesive layer 33 and the edge of opening 35 on the underside of insulating film 34. Distance DIS4 is the distance between the edge of opening 36 on the underside of adhesive layer 33 and the edge of opening 36 on the underside of insulating film 34. Distances DIS3 and DIS4 correspond to the resin flow width. Note that width W1, width W2, distance DIS3, and distance DIS4 are measured based on a planar image of printed wiring board 100 obtained using a microscope.

[0043] The distance DIS3 is 30 percent or less of the minimum value of the width W1. That is, the value obtained by dividing the distance DIS3 by the minimum value of the width W1 is 0.3 or less. The distance DIS4 is 30 percent or less of the minimum value of the width W2. That is, the value obtained by dividing the distance DIS4 by the minimum value of the width W2 is 0.30 or less. The distances DIS3 and DIS4 are, for example, 0 mm or more and 0.3 mm or less.

[0044] (Method of manufacturing printed wiring board 100) A method for manufacturing the printed wiring board 100 will be described below.

[0045] 7 is a manufacturing process diagram of the printed wiring board 100. As shown in Fig. 7, the manufacturing method of the printed wiring board 100 includes a preparation step S1 and a coverlay application step S2. The coverlay application step S2 is performed after the preparation step S1.

[0046] In the preparation step S1, a base film 10, a coverlay 31, and a coverlay 32 are prepared. Note that the base film 10 prepared in the preparation step S1 has conductive patterns 21 and 22 arranged on the main surfaces 10a and 10b, respectively. In the coverlays 31 and 32 prepared in the preparation step S1, the adhesive constituting the adhesive layer 33 is uncured. In the coverlays 31 and 32, openings 35 and 36 are formed, respectively, by, for example, punching.

[0047] In the coverlay attachment step S2, the coverlays 31 and 32 are attached to the base film 10. In the coverlay attachment step S2, first, the coverlay 31 is placed on the main surface 10a so that the adhesive layer 33 covers the conductive pattern 21, and the coverlay 32 is placed on the main surface 10b so that the adhesive layer 33 covers the conductive pattern 22.

[0048] Second, the coverlays 31 and 32 are heat-pressed onto the base film 10. At this time, a cushioning material is interposed between the heat-pressing device and the coverlays 31 and 32. This hardens the adhesive that constitutes the adhesive layer 33, and the coverlays 31 and 32 are attached to the base film 10.

[0049] The cushioning material is made of a resin material. The glass transition point of the resin material constituting the cushioning material is lower than the heating temperature during the heat pressing. Therefore, during the heat pressing, the insulating film 34 deforms to conform to the shapes of the plurality of wiring portions 21a (wiring portions 22a), and periodic concaves and convexes are formed along the third direction DR3 on the upper surface of the insulating film 34 above the plurality of wiring portions 21a (wiring portions 22a). As a result, the printed wiring board 100 having the structure shown in FIGS. 1 to 6 is formed.

[0050] <Modification> 8 is a cross-sectional view of a modified printed wiring board 100. As shown in FIG. 8, the printed wiring board 100 does not necessarily have to have the conductive pattern 22 and the coverlay 32.

[0051] (Effects of the printed wiring board 100) The effects of the printed wiring board 100 will be described below.

[0052] The resin flow width is small in printed wiring board 100. More specifically, in printed wiring board 100, distance DIS3 is 30 percent or less of the minimum value of width W1, and distance DIS4 is 1 percent or less of the minimum value of width W2. Therefore, in printed wiring board 100, the area of ​​the top surfaces of lands 21d and 22d, which are used for electrical connection to the outside, is ensured.

[0053] The higher the aspect ratio of the conductive patterns 21 and 22 (i.e., the larger the thickness T1 and thickness T2), and the higher the density of the conductive patterns 21 and 22 (i.e., the smaller the distance DIS1 and distance DIS2), the more likely resin flow will occur when the coverlays 31 and 32 are applied.

[0054] However, in printed wiring board 100, thicknesses T5 and T6 are small, ranging from 2 μm to 7 μm. Furthermore, in printed wiring board 100, a cushioning material that softens easily (has a low glass transition point) is interposed between the heat press device and coverlays 31 and 32 when heat pressing is performed. Therefore, in printed wiring board 100, insulating film 34 is not easily deformed during heat pressing, and increases in distances DIS3 and DIS4 due to resin flow are unlikely to occur.

[0055] Large thicknesses T3 and T4 mean that the pressure applied during the heat press is small. The smaller the pressure applied during the heat press, the less likely resin flow occurs, and therefore, the larger thicknesses T3 and T4 are, the easier it is to ensure the area of ​​the top surfaces of lands 21d and 22d that are used for electrical connection with the outside.

[0056] On the other hand, the smaller the thicknesses T3 and T4, the closer the interface between the adhesive layer 33 and the insulating film 34 is to the neutral axis of the printed wiring board 100 when bent, making it easier to ensure adhesion between the adhesive layer 33 and the insulating film 34 when bent. When the thicknesses T3 and T4 are 3 μm or more and 15 μm or less, it is possible to ensure adhesion between the adhesive layer 33 and the insulating film 34 while also ensuring the area of ​​the top surfaces of the lands 21d and 22d that are used for electrical connection to the outside.

[0057] (Example) Samples 1 to 72 were prepared to evaluate the relationship between thickness T1 (thickness T2), thickness T3 (thickness T4), thickness T5 (thickness T6), and distance DIS1 (distance DIS2) and distance DIS3 (distance DIS4). Details of Samples 1 to 72 are shown in Tables 1, 2, and 3. For Samples 1 to 72, the thickness T1, thickness T3, thickness T5, and distance DIS1 were varied, and then the distance DIS3 was measured. Note that for Samples 1 to 72, the width W1 was constant at 0 μm.

[0058] [Table 1]

[0059] [Table 2]

[0060] [Table 3]

[0061] Condition A is that thickness T1 is 30 μm or more and 150 μm or less. Condition B is that thickness T3 is 3 μm or more and 15 μm or less. Condition C is that thickness T5 is 2 μm or more and 7 μm or less. Condition D is that distance DIS1 is 3 μm or more and 30 μm or less.

[0062] All of conditions A to D were satisfied in Samples 1 to 51, Sample 53, Sample 54, Sample 57, Sample 61, Sample 62, and Sample 65. On the other hand, at least one of conditions A to D was not satisfied in Sample 52, Sample 55, Sample 56, Samples 58 to 60, Sample 63, Sample 64, and Samples 66 to 72.

[0063] In Samples 1 to 51, Sample 53, Sample 54, Sample 57, Sample 61, Sample 62, and Sample 65, the distance DIS3 was 0 mm or more and 0.3 mm or more (i.e., the distance DIS3 was 30 percent or less of the width W1). On the other hand, in Samples 52, Sample 55, Sample 56, Samples 58 to 60, Sample 63, Sample 64, and Samples 66 to 72, the distance DIS3 exceeded 0.3 mm.

[0064] This comparison revealed that by appropriately adjusting the thickness T1 (thickness T2), thickness T3 (thickness T4), thickness T5 (thickness T6) and distance DIS1 (distance DIS2), it is possible to set the distance DIS3 (distance DIS4) to be between 0 mm and 0.3 mm (i.e., 30 percent or less of the width W1 (width W2)).

[0065] The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above-described embodiments, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0066] 100 printed wiring board, 10 base film, 10a main surface, 10b main surface, 10c through hole, 21 conductive pattern, 21a wiring portion, 21b straight portion, 21c curved portion, 21d, 21e land, 22 conductive pattern, 22a wiring portion, 22b straight portion, 22c curved portion, 22d, 22e land, 23 seed layer, 24 electroless plating layer, 25 electrolytic plating layer, 31, 32 coverlay, 33 adhesive layer, 34 insulating film, 35, 36 opening, DIS1, DIS2, DIS3, DIS4 distance, DR1 first direction, DR2 second direction, DR3 third direction, P1, P2 pitch, S1 preparation process, S2 coverlay attachment process, T1, T2, T3, T4, T5, T6 thickness, W1, W2 width.

Claims

1. a base film having a major surface; a conductive pattern disposed on the main surface; a coverlay including an adhesive layer disposed on the main surface so as to cover the conductive pattern and an insulating film disposed on the adhesive layer; the conductive pattern has a terminal portion, an opening is formed in the coverlay to penetrate the coverlay and expose an upper surface of the terminal portion; When the edge of the opening on the lower surface of the adhesive layer and the edge of the opening on the lower surface of the insulating film are defined as a first opening edge and a second opening edge, respectively, a resin flow width, which is a distance between the first opening edge and the second opening edge, is 30% or less of a minimum width of the first opening edge, the thickness of the adhesive layer between the upper surface of the conductive pattern and the lower surface of the insulating film is 3 μm or more and 15 μm or less; the conductive pattern has a plurality of wiring portions, a normal to the main surface is along a first direction; each of the plurality of wiring portions extends along a second direction perpendicular to the first direction; the plurality of wiring portions are arranged along a third direction perpendicular to the first direction and the second direction, A printed wiring board, wherein the period of the unevenness on the upper surface of the insulating film is 0.80 to 1.20 times the pitch between two adjacent ones of the plurality of wiring portions in the portion of the insulating film above the plurality of wiring portions.

2. The printed wiring board according to claim 1 , wherein the resin flow width is 0 mm or more and 0.3 mm or less.

3. 2. The printed wiring board according to claim 1, wherein the conductive pattern has a thickness of 30 [mu]m or more and 150 [mu]m or less.

4. The printed wiring board according to claim 1 , wherein the distance between two adjacent ones of the plurality of wiring portions is not less than 3 μm and not more than 30 μm.

5. 2. The printed wiring board according to claim 1, wherein the arithmetic mean height of the irregularities on the upper surface of the insulating film is 0.010 μm or more and 1.00 μm or less.

6. 6. The printed wiring board according to claim 1, wherein the insulating film is made of polyimide or liquid crystal polymer.

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