Printed wiring board

Abstract

This printed wiring board is provided with: a base film having a main surface; a conductive pattern disposed on the main surface; and a cover layer 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 cover layer is provided with an opening part which penetrates through the cover layer and exposes the upper surface of the terminal part. If the edge of the opening in the lower surface of the adhesive layer and the edge of the opening in the lower surface of the insulating film are respectively a first opening edge and a second opening edge, the minimum value of the resin flow width, which is the distance between the first opening edge and the second opening edge, with respect to the width of the first opening edge is 30% or less.

Description

Technical Field

[0001] This disclosure relates to printed wiring boards. Background Technology

[0002] For example, International Patent 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 along a direction orthogonal to the normal of the main surface of the base film. The insulating layer is disposed on the main surface of the base film to cover the conductive pattern.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2016 / 147993 Summary of the Invention

[0006] The printed wiring board disclosed herein comprises: a base film having a main surface; a conductive pattern disposed on the main surface; and a cover layer having an adhesive layer and an insulating film, the adhesive layer being disposed on the main surface such that it covers the conductive pattern, and the insulating film being disposed on the adhesive layer. The conductive pattern has a terminal portion. An opening is formed in the cover layer, penetrating the cover layer and exposing the upper surface of the terminal portion. If the edge of the opening in the lower surface of the adhesive layer and the edge of the opening in the lower surface of the insulating film are respectively designated as a first opening edge and a second opening edge, then the minimum value of the resin flow width, which is the distance between the first opening edge and the second opening edge, relative to the width of the first opening edge is 30% or less. Attached Figure Description

[0007] Figure 1 This is a top view of the printed wiring board 100.

[0008] Figure 2 This is a bottom view of the printed wiring board 100.

[0009] Figure 3 yes Figure 1 The cross-sectional view at point III-III.

[0010] Figure 4 yes Figure 1 The cross-sectional view at point IV-IV.

[0011] Figure 5 yes Figure 1 The cross-sectional view at point VV.

[0012] Figure 6 yes Figure 1 The cross-sectional view at VI-VI.

[0013] Figure 7 This is a manufacturing process diagram of the printed wiring board 100.

[0014] Figure 8 This is a cross-sectional view of the printed wiring board 100 involved in the modified example. Detailed Implementation

[0015] [The technical problem this disclosure aims to solve]

[0016] An insulating layer, for example, is sometimes used as a cover layer. The cover layer has an adhesive layer and an insulating film, the adhesive layer being disposed on the main surface of the base film in a manner that covers the conductive pattern, and the insulating film being disposed on the adhesive layer. In order to electrically connect the conductive pattern to the outside, openings are formed in the cover layer to expose the upper surface of the terminal portion of the conductive pattern.

[0017] The opening edge of the opening on the lower surface of the adhesive layer is designated as the first opening edge, and the opening edge of the opening on the lower surface of the insulating film is designated as the second opening edge. When the cover layer is adhered to the base film, adhesive layer flow (resin flow) sometimes occurs, causing the first opening edge to be located further inward than the second opening edge when viewed from above. If, as a result of resin flow, the distance between the first and second opening edges (resin flow width) becomes too large, the area of ​​the upper surface of the conductive pattern used for external electrical connection becomes too small.

[0018] This disclosure is made in view of the problems of the prior art as described above. More specifically, this disclosure provides a printed wiring board that can ensure the connection area of ​​the terminal portions of conductive patterns.

[0019] [The Effects of This Disclosure]

[0020] According to the printed wiring board disclosed herein, the connection area of ​​the terminal section can be ensured.

[0021] [Description of embodiments of this disclosure]

[0022] First, embodiments of this disclosure will be described.

[0023] (1) The printed wiring board according to the embodiment includes: a base film having a main surface; a conductive pattern disposed on the main surface; and a cover layer having an adhesive layer and an insulating film, the adhesive layer being disposed on the main surface in a manner covering the conductive pattern, and the insulating film being disposed on the adhesive layer. The conductive pattern has a terminal portion. An opening is formed in the cover layer, penetrating the cover layer and exposing the upper surface of the terminal portion. If the edge of the opening in the lower surface of the adhesive layer and the edge of the opening in the lower surface of the insulating film are respectively designated as a first opening edge and a second opening edge, then the minimum value of the resin flow width, which is the distance between the first opening edge and the second opening edge, relative to the width of the first opening edge is 30% or less. According to the printed wiring board of (1) above, the connection area of ​​the terminal portion can be ensured.

[0024] (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.

[0025] (3) In the printed wiring board of (1) above, the thickness of the insulating film may be 2 μm or more and 7 μm or less. According to the printed wiring board of (3) above, the connection area of ​​the terminal portion can be further ensured.

[0026] (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. According to the printed wiring board of (4) above, the adhesion between the adhesive layer and the insulating film can be ensured while ensuring the connection area of ​​the terminal portion.

[0027] (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. According to the printed wiring board of (5) above, the connection area of ​​the terminal portion can be ensured even when resin flow is likely to occur.

[0028] (6) In the printed wiring board of (1) above, the conductive pattern may have multiple wiring portions. The normal to the main surface may be along a first direction. Each of the multiple wiring portions may be along a second direction orthogonal to the first direction. The multiple wiring portions may be arranged along a third direction orthogonal to both the first and second directions. The distance between two adjacent wiring portions may be 3 μm or more and 30 μm or less. According to the printed wiring board of (6) above, the connection area of ​​the terminal portions can be ensured even in situations where resin flow is likely to occur.

[0029] (7) In the printed wiring board of (1) above, the arithmetic mean height of the unevenness on the upper surface of the insulating film may be 0.010 μm or more and 1.00 μm or less.

[0030] (8) In the printed wiring board of (1) above, the conductive pattern may have multiple wiring portions. The normal to the main surface may be along a first direction. Each of the multiple wiring portions may be along a second direction orthogonal to the first direction. The multiple wiring portions may be arranged along a third direction orthogonal to both the first and second directions. In the portion of the insulating film located on the multiple wiring portions, the period of the unevenness on the upper surface of the insulating film may be more than 0.80 times and less than 1.20 times the pitch between two adjacent wiring portions.

[0031] (9) In the printed wiring boards of (1) to (9) above, the insulating film may also be formed of polyimide or liquid crystal polymer.

[0032] [Details of the embodiments of this disclosure]

[0033] Next, while referring to the appendix Figure 1 The details of embodiments of this disclosure will be described below. In the following drawings, the same or equivalent parts will be labeled with the same reference numerals, and repeated descriptions will not be given. The printed wiring board involved in the embodiments will be referred to as printed wiring board 100.

[0034] (Composition of printed wiring board 100)

[0035] The following describes the structure of the printed wiring board 100.

[0036] Figure 1 This is a top view of the printed wiring board 100. Figure 2 This is a bottom view of the printed wiring board 100. Figure 2 The text shows the relationship between... Figure 1 Printed wiring board 100 as observed from the opposite side. Figure 1 China and Figure 2 The illustrations of overlay layer 31 and overlay layer 32 are omitted in the text. Figure 3 yes Figure 1 The cross-sectional view at point III-III. Figure 4 yes Figure 1 The cross-sectional view at point IV-IV. Figure 5 yes Figure 1 The cross-sectional view at point VV. Figure 6 yes Figure 1 The cross-sectional view at VI-VI. (See diagram below.) Figures 1 to 6 As shown, the printed wiring board 100 has a base film 10, conductive patterns 21 and 22, and cover layers 31 and 32.

[0037] The base film 10 has a main surface 10a and a main surface 10b. Main surfaces 10a and 10b are end faces of the base film 10 in the thickness direction. Main surface 10b is the opposite surface of main surface 10a. The base film 10 is formed of a flexible, electrically insulating material. The base film 10 is formed, for example, of polyimide or a liquid crystal polymer. The normal direction of the main surfaces 10a (and 10b) is defined as a first direction DR1.

[0038] A conductive pattern 21 is disposed on the main surface 10a. When viewed from above, the conductive pattern 21 is coiled into a vortex shape. The conductive pattern 21 has multiple wiring portions 21a.

[0039] The multiple wiring portions 21a can be either multiple straight portions 21b or multiple curved portions 21c. The straight portions 21b extend in a straight line when viewed from above. The curved portions 21c extend in a curved shape when viewed from above. The extending direction of the wiring portions 21a (straight portions 21b, curved portions 21c) is defined as a second direction DR2. It should be noted that when the wiring portion 21a is a curved portion 21c, the second direction DR2 is the tangential direction of the curved portion 21c.

[0040] Multiple wiring sections 21a (straight sections 21b and curved sections 21c) are arranged at intervals along a third direction DR3. The third direction DR3 is a direction orthogonal to the first direction DR1 and the second direction DR2.

[0041] Conductive pattern 22 is disposed on main surface 10b. Conductive pattern 22 is spiraled into a vortex shape when viewed from above. Conductive pattern 21 has multiple wiring portions 22a.

[0042] The multiple wiring portions 22a can be either multiple straight portions 22b or multiple curved portions 22c. The straight portions 22b extend in a straight line when viewed from above. The curved portions 22c extend in a curved shape when viewed from above. The wiring portions 22a (straight portions 22b, curved portions 22c) extend along a second direction DR2. It should be noted that when the wiring portion 22a is a curved portion 22c, the second direction DR2 is the tangent direction of the curved portion 22c. The multiple wiring portions 22a (straight portions 22b, curved portions 22c) are arranged at intervals along a third direction DR3.

[0043] Conductive pattern 21 has a pad 21d at one end and a pad 21e at the other end. Pads 21d and 21e are located at the outermost and innermost peripheries of conductive pattern 21, respectively. Conductive pattern 22 has a pad 22d at one end and a pad 22e at the other end. Pads 22d and 22e are located at the innermost and outermost peripheries of conductive pattern 22, respectively. Pads 21d and 22e are terminals for external electrical connection. Pads 21e and 22d overlap when viewed from above.

[0044] Conductive patterns 21 and 22 are each formed, for example, by a semi-additive process. More specifically, conductive patterns 21 and 22 each have a seed layer 23, an electroless plating layer 24, and an electrolytic plating layer 25. However, conductive patterns 21 and 22 can also be formed by a subtractive process.

[0045] A 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 may have 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 and second layers are, for example, formed of a nickel-chromium alloy and copper, respectively.

[0046] Electroless plating layer 24 is formed by electroless plating. Electroless plating layer 24 is disposed on seed layer 23. Electroless plating layer 24 is formed, for example, by copper. Electrolytic plating layer 25 is formed by electrolytic plating. Electrolytic plating layer 25 is disposed on electroless plating layer 24. Electrolytic plating layer 25 is formed, for example, by copper.

[0047] Although not shown, a through-hole 10c is formed in the base film 10. The through-hole 10c penetrates the base film 10 along the thickness direction. When viewed from above, the through-hole 10c overlaps with pads 21e and 22d. An electroless plating layer 24 is also disposed on the inner wall surface of the through-hole 10c. An electrolytic plating layer 25 is also embedded in the through-hole 10c. Thus, conductive patterns 21 and 22 are electrically connected to each other. By applying a voltage between pads 21d and 22e, current flows in a vortex pattern in conductive patterns 21 and 22, generating a magnetic field. From another perspective, the printed wiring board 100 becomes a coil device.

[0048] The thickness of conductive pattern 21 is defined as thickness T1. The thickness of conductive pattern 22 is defined as thickness T2. Thickness T1 and thickness T2 are, for example, 30 μm or more and 150 μm or less. 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. Distance DIS1 and distance DIS2 are, for example, 3 μm or more and 30 μm or less.

[0049] Cover layers 31 and 32 each have an adhesive layer 33 and an insulating film 34. The adhesive layer 33 is a layer formed of adhesive. The adhesive layer 33 of cover layer 31 is disposed on the main surface 10a in a manner covering the conductive pattern 21. The adhesive layer 33 of cover layer 32 is disposed on the main surface 10b in a manner covering the conductive pattern 22. The insulating film 34 is disposed on the adhesive layer 33. The insulating film 34 is formed, for example, of polyimide or liquid crystal polymer.

[0050] The thickness of the adhesive layer 33 of the cover layer 31, located between the upper surface of the conductive pattern 21 and the lower surface of the insulating film 34 of the cover layer 31, is set as thickness T3. The thickness of the adhesive layer 33 of the cover layer 32, located between the upper surface of the conductive pattern 22 and the lower surface of the insulating film 34 of the cover layer 32, is set as thickness T4. Thickness T3 and thickness T4 are, for example, 3 μm or more and 15 μm or less.

[0051] The thickness of the insulating film 34 of the cover layer 31 is set to thickness T5. The thickness of the insulating film 34 of the cover layer 32 is set to thickness T6. The thicknesses T5 and T6 are, for example, 2 μm or more and 7 μm or less.

[0052] The arithmetic mean height (Sa) of the unevenness on the upper surface of the insulating film 34 is greater than 0.010 μm and less than 1.00 μm. The arithmetic mean height of the unevenness on the upper surface of the insulating film 34 is measured using a laser microscope. It should be noted that the definition of arithmetic mean height is as specified in ISO 25178.

[0053] The upper surface of the insulating film 34 has irregularities 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. On portions of the insulating film 34 located on the plurality of wiring portions 21a, the period of the irregularities on the upper surface of the insulating film 34 along the third direction DR3 is, for example, more than 0.80 times and less than 1.20 times the pitch P1. On portions of the insulating film 34 located on the plurality of wiring portions 22a, the period of the irregularities on the upper surface of the insulating film 34 along the third direction DR3 is, for example, more than 0.80 times and less than 1.20 times the pitch P2.

[0054] The period of the unevenness of the upper surface of the insulating film 34 on the third-direction DR3 is obtained by measuring the upper surface of the insulating film 34 at a magnification of 20x or higher and 50x or lower using a laser microscope and measuring the length of the interval between two adjacent protrusions.

[0055] An opening 35 is formed in the cover layer 31. The opening 35 penetrates the cover layer 31 (adhesive layer 33 and insulating film 34) in the thickness direction. The upper surface of the pad 21d is exposed through the opening 35. An opening 36 is formed in the cover layer 32. The opening 36 penetrates the cover layer 32 (adhesive layer 33 and insulating film 34) in the thickness direction. The upper surface of the pad 22e is exposed through the opening 36.

[0056] The widths of the openings 35 and 36 in the insulating film 34 are defined as width W1 and width W2, respectively. Widths W1 and W2 are measured on the lower surface of the insulating film 34. The distance between the edge of the opening 35 on the lower surface of the adhesive layer 33 and the edge of the opening 35 on the lower surface of the insulating film 34 is defined as distance DIS3. The distance between the edge of the opening 36 on the lower surface of the adhesive layer 33 and the edge of the opening 36 on the lower surface of the insulating film 34 is defined as distance DIS4. Distances DIS3 and DIS4 correspond to the resin flow width. It should be noted that a planar image of the printed wiring board 100 is obtained using a microscope, and the lengths of width W1, width W2, distance DIS3, and distance DIS4 are measured based on this planar image.

[0057] The minimum value of distance DIS3 relative to width W1 is 30% or less. That is, the value obtained by dividing distance DIS3 by the minimum value of width W1 is 0.3 or less. The minimum value of distance DIS4 relative to width W2 is 30% or less. That is, the value obtained by dividing distance DIS4 by the minimum value of width W2 is 0.30 or less. For example, distances DIS3 and DIS4 are 0 mm or more and 0.3 mm or less.

[0058] (Manufacturing method of printed wiring board 100)

[0059] The following describes the manufacturing method of the printed wiring board 100.

[0060] Figure 7 This is a manufacturing process diagram of printed wiring board 100. (Example) Figure 7 As shown, the manufacturing method of the printed wiring board 100 includes a preparation step S1 and a cover layer bonding step S2. The cover layer bonding step S2 is performed after the preparation step S1.

[0061] In preparation step S1, a base film 10, a capping layer 31, and a capping layer 32 are prepared. It should be noted that in the base film 10 prepared in preparation step S1, conductive patterns 21 and 22 are respectively disposed on the main surface 10a and the main surface 10b. In the capping layers 31 and 32 prepared in preparation step S1, the adhesive constituting the adhesive layer 33 is not cured. In the capping layers 31 and 32, openings 35 and 36 are formed, for example, by stamping.

[0062] In the cover layer bonding process S2, cover layer 31 and cover layer 32 are bonded to the base film 10. In the cover layer bonding process S2, firstly, cover layer 31 is disposed on the main surface 10a such that adhesive layer 33 covers conductive pattern 21, and cover layer 32 is disposed on the main surface 10b such that adhesive layer 33 covers conductive pattern 22.

[0063] Second, the cover layers 31 and 32 are hot-pressed relative to the base film 10. At this time, a cushioning material is placed between the hot-pressing device and the cover layers 31 and 32. As a result, the adhesive constituting the adhesive layer 33 is cured, and the cover layers 31 and 32 are adhered to the base film 10.

[0064] The cushioning material is formed from a resin material. The glass transition temperature of the resin material constituting the cushioning material is lower than the heating temperature during the hot pressing described above. Therefore, during the hot pressing, the insulating film 34 is deformed along the shape of the plurality of wiring portions 21a (wiring portions 22a), and periodic irregularities are formed along the third direction DR3 on the upper surface portion of the insulating film 34 located on the plurality of wiring portions 21a (wiring portions 22a). Through the above process, a cushioning material is formed... Figures 1 to 6 The printed wiring board 100 with the structure shown is shown.

[0065] <Variation Example>

[0066] Figure 8 This is a cross-sectional view of the printed wiring board 100 involved in the modified example. For example... Figure 8 As shown, the printed wiring board 100 may also not have the conductive pattern 22 and the cover layer 32.

[0067] (Effect of printed wiring board 100)

[0068] The following describes the effect of the printed wiring board 100.

[0069] In the printed wiring board 100, the resin flow width is reduced. More specifically, in the printed wiring board 100, the minimum distance of DIS3 relative to the width W1 is 30% or less, and the minimum distance of DIS4 relative to the width W2 is % or less. Therefore, in the printed wiring board 100, the area of ​​the upper surfaces of pads 21d and 22d for external electrical connections is ensured.

[0070] The higher the aspect ratio of conductive patterns 21 and 22 (i.e., the larger the thickness T1 and thickness T2), and the higher the density of conductive patterns 21 and 22 (i.e., the smaller the distance from DIS1 and distance from DIS2), the easier it is for resin to flow when bonding cover layer 31 and cover layer 32.

[0071] However, in the printed wiring board 100, the thicknesses T5 and T6 are reduced to 2 μm or more and 7 μm or less. Furthermore, in the printed wiring board 100, during hot pressing, a buffer material that is easily softened (low glass transition temperature) is placed between the hot pressing device and the cover layer 31 and cover layer 32. Therefore, in the printed wiring board 100, during hot pressing, the insulating film 34 deforms, and the increase in distances DIS3 and DIS4 due to resin flow is less likely to occur.

[0072] Larger thicknesses T3 and T4 mean lower pressure applied during hot pressing. Since lower pressure during hot pressing makes it less likely for resin to flow, larger thicknesses T3 and T4 make it easier to ensure the area of ​​the upper surfaces of pads 21d and 22d for external electrical connections.

[0073] 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, and the easier it is to ensure the 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 the adhesion between the adhesive layer 33 and the insulating film 34 while ensuring the area of ​​the upper surface of the pads 21d and 22d for external electrical connection.

[0074] (Example)

[0075] To evaluate the relationship between thicknesses T1 (thickness T2), T3 (thickness T4), T5 (thickness T6), and distances DIS1 (distance DIS2) and DIS3 (distance DIS4), samples 1 to 72 were prepared. Details of samples 1 to 72 are shown in Tables 1, 2, and 3. In samples 1 to 72, distance DIS3 was measured after varying thicknesses T1, T3, T5, and distance DIS1. It should be noted that the width W1 was fixed at 0 μm in samples 1 to 72.

[0076] [Table 1]

[0077]

[0078] [Table 2]

[0079]

[0080] [Table 3]

[0081]

[0082] Condition A is defined as a thickness T1 of 30 μm or more and 150 μm or less. Condition B is defined as a thickness T3 of 3 μm or more and 15 μm or less. Condition C is defined as a thickness T5 of 2 μm or more and 7 μm or less. Condition D is defined as a distance from DIS1 of 3 μm or more and 30 μm or less.

[0083] In samples 1 through 51, 53, 54, 57, 61, 62, and 65, all conditions A through D are satisfied. On the other hand, in samples 52, 55, 56, 58 through 60, 63, 64, and 66 through 72, at least one of conditions A through D is not satisfied.

[0084] In samples 1 to 51, 53, 54, 57, 61, 62, and 65, the distance to DIS3 is 0 mm or more and 0.3 mm or more (i.e., the distance to DIS3 is less than 30% of the width W1). On the other hand, in samples 52, 55, 56, 58 to 60, 63, 64, and 66 to 72, the distance to DIS3 exceeds 0.3 mm.

[0085] The comparison shows that by appropriately adjusting the thicknesses T1 (thickness T2), T3 (thickness T4), T5 (thickness T6) and distance DIS1 (distance DIS2), the distance DIS3 (distance DIS4) can be made to be 0 mm or more and 0.3 mm or less (i.e., less than 30% of the width W1 (width W2)).

[0086] It should be understood that the embodiments disclosed herein are exemplary in all respects and not restrictive. The scope of the invention is shown not by the above embodiments but by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0087] Explanation of reference numerals in the attached figures

[0088] 100: Printed wiring board; 10: Base film; 10a: Main surface; 10b: Main surface; 10c: Through-hole; 21: Conductive pattern; 21a: Wiring section; 21b: Straight section; 21c: Curved section; 21d, 21e: Pads; 22: Conductive pattern; 22a: Wiring section; 22b: Straight section; 22c: Curved section; 22d, 22e: Pads; 23: Seed layer; 24: Electroless plating layer; 25: Electrolytic plating layer. Coating; 31, 32: Covering layer; 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: Covering layer bonding process; T1, T2, T3, T4, T5, T6: Thickness; W1, W2: Width.

Claims

1. A printed wiring board, comprising: The base film has a main surface; Conductive patterns are disposed on the main surface; and A cover layer has an adhesive layer and an insulating film, the adhesive layer being disposed on the main surface in a manner covering the conductive pattern, and the insulating film being disposed on the adhesive layer. The conductive pattern has a terminal portion. An opening is formed in the cover layer that penetrates the cover layer 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 respectively designated as the first opening edge and the second opening edge, then the minimum value of the resin flow width, which is the distance between the first opening edge and the second opening edge, relative to the width of the first opening edge is 30% or less.

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

3. The printed wiring board according to claim 1, wherein, The thickness of the insulating film is greater than 2 μm and less than 7 μm.

4. The printed wiring board according to claim 1, wherein, The thickness of the adhesive layer located between the upper surface of the conductive pattern and the lower surface of the insulating film is more than 3 μm and less than 15 μm.

5. The printed wiring board according to claim 1, wherein, The thickness of the conductive pattern is greater than 30 μm and less than 150 μm.

6. The printed wiring board according to claim 1, wherein, The conductive pattern has multiple wiring portions. The normal to the main surface is along the first direction. The plurality of wiring sections are each arranged along a second direction orthogonal to the first direction. The plurality of wiring sections are arranged along a third direction orthogonal to the first direction and the second direction. The distance between any two adjacent wiring sections is more than 3 μm and less than 30 μm.

7. The printed wiring board according to claim 1, wherein, The arithmetic mean height of the unevenness on the upper surface of the insulating film is greater than 0.010 μm and less than 1.00 μm.

8. The printed wiring board according to claim 1, wherein, The conductive pattern has multiple wiring portions. The normal to the main surface is along the first direction. The plurality of wiring sections are each arranged along a second direction orthogonal to the first direction. The plurality of wiring sections are arranged along a third direction orthogonal to the first direction and the second direction. In the portion of the insulating film located on the plurality of wiring portions, the period of the unevenness on the upper surface of the insulating film is more than 0.80 times and less than 1.20 times the pitch between two adjacent wiring portions.

9. The printed wiring board according to any one of claims 1 to 8, wherein, The insulating film is formed of polyimide or liquid crystal polymer.

Images