Wiring board and method for producing same

Abstract

A wiring board according to the present disclosure comprises: an insulating board that has a through hole; a conductor layer that is positioned on at least a part of the surface of the insulating board and the inner wall surface of the through hole; and an organic resin layer that covers the insulating board and the conductor layer. The organic resin layer has a filling part that is positioned within the through hole.

Description

Wiring board and manufacturing method thereof

[0001] The present disclosure relates to a wiring board and a manufacturing method thereof.

[0002] Wiring boards for communications, radar, and the like require the provision of a waveguide within the wiring board. For example, through-holes that penetrate the top and bottom surfaces of a wiring board are used as waveguides, or as described in Patent Document 1, through-holes that penetrate the top and bottom surfaces of a wiring board are filled with resin and used as waveguides. When through-holes that penetrate the top and bottom surfaces of a wiring board are used as waveguides, an antenna board and a control board must be prepared and assembled separately. On the other hand, when through-holes that penetrate the top and bottom surfaces of a wiring board are filled with resin and used as waveguides, the wiring board, antenna board, and control board can be integrated.

[0003] When a through-hole that penetrates the top and bottom surfaces of a wiring board is filled with resin and used as a waveguide, the resin is filled by, for example, a printing method. When resin is filled by a printing method, voids are formed in the resin, which results in an uneven dielectric constant and increases loss due to reflection.

[0004] JP 2010-251688 A

[0005] The wiring board according to the present disclosure includes an insulating substrate having a through hole, a conductor layer located on the inner wall surface of the through hole and on at least a portion of the surface of the insulating substrate, and an organic resin layer covering the insulating substrate and the conductor layer. The organic resin layer has a filling portion located in the through hole.

[0006] The method for manufacturing a wiring board according to the present disclosure includes the steps of preparing an insulating substrate having through holes, forming a conductor layer on the inner wall surfaces of the through holes and on at least a portion of the surface of the insulating substrate, covering the insulating substrate and the conductor layer with an organic resin film, subjecting the insulating substrate and the conductor layer to a heating and pressure treatment to fill a portion of the organic resin film into the through holes, and curing the organic resin film to form an organic resin layer.

[0007] 1A and 1B are explanatory views for explaining a main part of a wiring board according to an embodiment of the present disclosure and a main part of a wiring board according to another embodiment of the present disclosure.

[0008] As described above, when a through-hole penetrating the top and bottom surfaces of a wiring board is filled with resin and used as a waveguide, the resin is filled by, for example, a printing method. When resin is filled by a printing method, voids are formed in the resin, which results in an uneven dielectric constant and increases loss due to reflection.

[0009] The wiring board according to the present disclosure has the configuration described in the section on means for solving the above problems, thereby reducing dielectric loss in through-holes filled with resin. Furthermore, the method for manufacturing a wiring board according to the present disclosure has the configuration described in the section on means for solving the above problems, thereby reducing the formation of voids when filling through-holes with resin. Therefore, a wiring board can be obtained in which the resin-filled through-holes function as waveguides with low dielectric loss.

[0010] A wiring board according to an embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is an explanatory diagram for explaining a main part of a wiring board according to an embodiment of the present disclosure. Specifically, Fig. 1 shows the vicinity of a through hole 11 formed in an insulating substrate 1.

[0011] The insulating substrate 1 is not limited as long as it is made of an insulating material. Examples of insulating materials include resins and ceramics. Examples of resins include epoxy resins, bismaleimide-triazine resins, polyimide resins, polyphenylene ether resins, and liquid crystal polymers. These resins may be used alone or in combination of two or more. Examples of ceramics include alumina. The thickness of the insulating substrate 1 is not particularly limited and is, for example, 0.2 mm or more and 3.0 mm or less.

[0012] The insulating substrate 1 may contain an inorganic insulating filler. Examples of the inorganic insulating filler include silica, alumina, barium sulfate, talc, clay, glass, calcium carbonate, and titanium oxide. The inorganic insulating filler may be used alone or in combination of two or more types.

[0013] The insulating substrate 1 may contain a reinforcing material. Examples of the reinforcing material include insulating fabric materials such as glass fiber, glass nonwoven fabric, aramid nonwoven fabric, aramid fiber, and polyester fiber. The reinforcing material may be used alone or in combination of two or more types.

[0014] The insulating substrate 1 includes through holes 11 that penetrate from the top surface to the bottom surface. The through holes 11 are holes for positioning the conductor layers 2 to electrically connect the top and bottom surfaces of the insulating substrate 1. The number of through holes 11 is set appropriately depending on the size of the wiring board, etc. Typically, the number of through holes 11 included in one wiring board is 1,000 to 30,000. Furthermore, the diameter of the through holes 11 is, for example, 200 μm to 2,000 μm.

[0015] A conductor layer 2 is located on at least a portion of the inner wall surface of the through hole 11 and the surface of the insulating substrate 1. The conductor layer 2 is not limited as long as it is a conductor such as a metal. Specifically, the conductor layer 2 is formed of a metal foil such as copper foil, a metal plating such as copper plating, or the like. The thickness of the conductor layer 2 is not particularly limited and is, for example, 20 μm or more and 40 μm or less, and the thickness may be different between the inner wall surface of the through hole 11 and the surface of the insulating substrate 1. The thickness of the conductor layer 2 located on the inner wall surface of the through hole 11 may be, for example, 10 μm or more and 30 μm or less, and the thickness of the conductor layer 2 located on the surface of the insulating substrate 1 may be, for example, 20 μm or more and 40 μm or less.

[0016] Here, of the conductor layer 2, the portion located on the surface 1a of the insulating substrate 1 may be referred to as the surface conductor layer 2a, and the portion located on the inner wall surface of the through hole 11 may be referred to as the through hole conductor layer 2b. In this wiring board, the surface conductor layer 2a and the through hole conductor layer 2b are integrally formed.

[0017] The organic resin layer 3 covers the surface of the insulating substrate 1 and the surface of the conductor layer 2. The thickness of the organic resin layer 3 is not limited as long as it can cover the surface of the insulating substrate 1 and the surface of the conductor layer 2. The thickness of the organic resin layer 3 is, for example, 0.025 mm or more and 0.2 mm or less.

[0018] The resin forming the organic resin layer 3 is not limited as long as it is an organic resin, and examples thereof include cyclic olefin polymers, epoxy resins, bismaleimide-triazine resins, polyimide resins, polyphenylene ether resins, and liquid crystal polymers. Among these resins, it is preferable to use cyclic olefin polymers.

[0019] A cyclic olefin polymer is a polyolefin polymer having a cyclic structure. In addition to polymers using only one type of cyclic olefin as a monomer, cyclic olefin polymers also include cyclic olefin copolymers obtained by polymerizing a cyclic olefin with another monomer copolymerizable with the cyclic olefin. The ratio of the cyclic olefin to the other monomer is not particularly limited. For example, the other monomer is used in a ratio of 2 to 20 parts by mass per 100 parts by mass of the cyclic olefin.

[0020] Examples of cyclic olefins include norbornene-based monomers, cyclic diene-based monomers, and vinyl alicyclic hydrocarbon-based monomers. Specific examples of cyclic olefins include norbornene, vinylnorbornene, phenylnorbornene, dicyclopentadiene, tetracyclododecene, cyclopropene, cyclobutene, cyclopentene, cyclohexene, cyclohexadiene, and cyclooctadiene. These cyclic olefins may be used alone or in combination of two or more.

[0021] Examples of other monomers copolymerizable with the cyclic olefin include chain olefins, acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, aromatic vinyl compounds, unsaturated nitriles, and aliphatic conjugated dienes.

[0022] Specific examples of such monomers include ethylene, propylene, butene, acrylic acid, methacrylic acid, fumaric acid, fumaric anhydride, maleic acid, maleic anhydride, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, styrene, vinyl toluene, acrylonitrile, methacrylonitrile, 1,3-butadiene, 2-methyl-1,3-butadiene, and 2,3-dimethyl-1,3-butadiene. These other monomers may be used alone or in combination of two or more.

[0023] The organic resin layer 3 has a filling portion 31 located in the through hole 11. That is, the filling portion 31 is formed by filling a portion of the organic resin layer 3 into the through hole 11. Because the filling portion 31 is part of the organic resin layer 3, voids are less likely to form compared to when the through hole 11 is separately filled with organic resin. This results in a uniform dielectric constant, which can reduce loss due to reflection. By including such a filling portion 31, the wiring board according to one embodiment reduces dielectric loss occurring in the through hole 11. As a result, the filling portion 31 located in the through hole 11 is used as an excellent waveguide.

[0024] In this case, when the portion of the organic resin layer 3 excluding the filling portion 31 is defined as the covering portion 32, it is preferable that the filling portion 31 and the covering portion 32 are formed of the same material. The organic resin layer 3 is integrated from the covering portion 32 to the filling portion 31.

[0025] As shown in Fig. 1, a part (end 31a) of this filling portion 31 may protrude from the surface 1b of the insulating substrate 1. In Fig. 1, the protruding part of the filling portion 31 is shown as protruding portion 31A. Protruding portion 31A is a portion located outward from the surface 1b of the insulating substrate 1. The portion excluding protruding portion 31A may be referred to as the main body of the filling portion 31.

[0026] The protruding portion 31A may reach the position of the outer surface 2aa of the surface conductor layer 2a from the surface 1b of the insulating substrate 1. When the protruding portion 31A reaches the position of the outer surface 2aa of the surface conductor layer 2a from the surface 1b of the insulating substrate 1, the filling portion 31 tends to have a high filling rate over the entire longitudinal direction of the through hole 11.

[0027] Furthermore, even when a large number of through holes 11 are provided around the periphery of the main surface of the wiring board, it is easy to obtain a filled portion 31 with a small difference in filling rate across the entire periphery of the main surface of the wiring board. This is because printing using paste is a method of applying paste in one direction, which makes it easy for pressure differences to occur on the surface 1a of the insulating substrate 1. On the other hand, in the method of pressurizing and heating an organic resin film, pressure is applied to the surface 1a of the insulating substrate 1 all at once. Therefore, pressure differences are less likely to occur on the surface 1a of the insulating substrate 1.

[0028] The organic resin layer 3 may be formed solely from an organic resin such as the above-mentioned cyclic olefin polymer, or may contain a predetermined proportion of an inorganic filler in the organic resin. The content of the inorganic filler is preferably a volume fraction of 10 to 70 parts by volume, where the volume of the organic resin layer 3 is taken as 100 parts.

[0029] The organic resin layer 3 may contain a flame retardant and a weather stabilizer in addition to the inorganic filler. In this case, the content of the flame retardant in the organic resin layer 3 may be greater than the content of the weather stabilizer. The inorganic filler and the flame retardant may be present in equal amounts. The weather stabilizer may be unevenly distributed in the surface portion of the organic resin layer 3.

[0030] By simultaneously including an inorganic filler, a flame retardant, and a weather stabilizer in the organic resin layer 3, the reliability of the wiring board including the organic resin layer 3 can be improved in terms of mechanical strength, flame retardancy, moisture resistance, heat resistance, and the like.

[0031] The volumetric proportions of the organic resin, inorganic filler, flame retardant, and weather stabilizer contained in the organic resin layer 3 can be determined, for example, from an electron microscope photograph of a cross section of a wiring board. In this case, first, each component contained in the photographed area (e.g., 5 μm × 5 μm to 20 μm × 20 μm) is identified using an analyzer attached to the electron microscope. Next, the outline of each component is determined on the photograph. Then, the total area of ​​the outline for each component is calculated. Next, the total area of ​​each component is divided by the area of ​​the photographed area to determine the area proportion of each component. The area proportions thus determined are used as the volume proportions in the organic resin layer 3.

[0032] The organic resin layer 3 is preferably formed integrally from the surface 1a of the insulating substrate 1 to the filling portion 31 located in the through-hole 11. In other words, the filling portion 31 extending from the covering portion 32 located on the insulating substrate 1 and the conductor layer 2 to the inside of the through-hole 11 is preferably an integral body. There should be no interface between the covering portion 32 and the filling portion 31.

[0033] "No interface exists" means that the covering portion 32 and the filling portion 31 are formed of the same material, and that no boundary-like boundary can be seen between the covering portion 32 and the filling portion 31 when viewed with an electron microscope. In other words, it means that no different material exists between the covering portion 32 and the filling portion 31 other than the materials that form the covering portion 32 and the filling portion 31. Therefore, the material that forms the covering portion 32 exists continuously from the covering portion 32 to the filling portion 31 in the through hole 11, and forms a structure of the same material.

[0034] When the portion of the covering portion 32 located above the through hole 11 is designated as the hole covering portion 32a, it is preferable that there be no interface between the hole covering portion 32a and the filling portion 31. The relationship between the hole covering portion 32a and the filling portion 31 should also be similar to that between the covering portion 32 and the filling portion 31 described above. As described above, the absence of an interface means that the hole covering portion 32a and the filling portion 31 are formed from the same material, and no boundary-like structure is observed between the hole covering portion 32a and the filling portion 31 even when examined with an electron microscope. In other words, there is no different material between the hole covering portion 32a and the filling portion 31 other than the materials forming the hole covering portion 32a and the filling portion 31. Therefore, the material forming the hole covering portion 32a is continuous from the hole covering portion 32a to the filling portion 31 in the through hole 11, forming a structure of the same material.

[0035] The organic resin layer 3 is preferably formed integrally with the covering portion 32, which is a portion of the surface 1a of the insulating substrate 1, the filling portion 31 located in the through hole 11, and the hole covering portion 32a located directly above the through hole 11. The organic resin layer 3 is preferably formed such that nothing other than the material forming the organic resin layer 3 exists between the covering portion 32 located on the surface 1a of the insulating substrate 1 and the filling portion 31 located in the through hole 11. The material forming the organic resin layer 3 means the organic resin that constitutes the organic resin layer 3.

[0036] When the organic resin layer 3 contains an inorganic filler such as silica particles in addition to the organic resin, it means that the components and ratio (composition) of the organic resin and the inorganic filler are the same from the hole-covering portion 32 a to the filling portion 31. In this case, the organic resin components being the same means, for example, that the main polymers constituting the organic resin are the same.

[0037] "The inorganic filler is the same" means, for example, that the metal oxide of the inorganic filler is the same. The inorganic filler is identified, for example, by atomic absorption spectrometry, X-ray diffraction, or X-ray fluorescence. "The ratio (composition) of the organic resin to the inorganic filler is the same" means that the volume ratio of the organic resin among the filling portion 31, the covering portion 32, and the hole covering portion 32a is within ±5%.

[0038] It is preferable that the organic resin layer 3 has no material other than the material forming the organic resin layer 3 between the filling portion 31 located in the through hole 11 and the hole covering portion 32a located directly above 11a of the through hole 11. It is preferable that the organic resin layer 3 has no interface between the covering portion 32, which is the portion located on the surface 1a of the insulating substrate 1, and the hole covering portion 32a located directly above 11a of the through hole 11. It is preferable that the organic resin layer 3 has no interface where different materials come into contact on an extension line 1aa along the surface 1a of the insulating substrate 1. It is preferable that the organic resin layer 3 has no material other than the material forming the organic resin layer 3 on an extension line 1aa along the surface 1a of the insulating substrate 1.

[0039] The absence of an interface on the extension line 1aa along the surface 1a of the insulating substrate 1, or the absence of anything other than the material forming the organic resin layer 3 on the extension line 1aa along the surface 1a of the insulating substrate 1, means that when the extension line 1aa along the surface 1a of the insulating substrate 1 is taken as a reference plane, no interface resulting from different members or different materials exists in the region of that reference plane.

[0040] The region of the reference plane includes the upper region 11bup and the lower region 11bun when the reference plane is used as a boundary. In other words, the interface is the boundary where substances containing different main components or substances with different compositions are adjacent to each other. In this case, it means that the substances containing different main components or substances with different compositions are not adjacent to each other.

[0041] The interface may extend in the thickness direction of the organic resin layer 3, and may extend from one surface to the other surface of the organic resin layer 3. The interface extending in the thickness direction of the covering portion 32 may also extend from one surface to the other surface of the covering portion 32. Furthermore, the interface between the filling portion 31 and the hole covering portion 32a may also extend over the entire diameter of the hole covering portion 32a.

[0042] In the organic resin layer 3, the orientation of the inorganic filler and the flame retardant may be different between the filling portion 31 located within the through hole 11 and the hole covering portion 32a located directly above the through hole 11. For example, the degree of orientation of the inorganic filler contained in the filling portion 31 located within the through hole 11 may be higher than the degree of orientation of the inorganic filler contained in the hole covering portion 32a located directly above the through hole 11.

[0043] When the organic resin layer 3 including the filling portion 31 is formed on the surface 1a of the insulating substrate 1 and in the through-hole 11, for example, when the diameter of the through-hole 11 is small (300 μm or less), the density of the filling portion 31 may be different between the vicinity of the surface 1a of the insulating substrate 1 and the central portion in the thickness direction of the insulating substrate 1. The density of the filling portion 31 may also be different between both surfaces of the insulating substrate 1. "The density of the filling portion 31 is different" means that there may be portions in the filling portion 31 where the density is partially different.

[0044] In this case, differences in the density of the filling portion 31 can be evaluated based on the area ratio of voids observed when observing the outer surface or internal cross section of the filling portion 31. This is because, as will be described later, the wiring board is manufactured by placing the organic resin layer 3 on one side of the insulating substrate 1 and then performing a pressurized and heated process. That is, the filling portion 31 in the wiring board is formed by placing a sheet-like organic resin film on the surface 1a of the insulating substrate 1 and then performing pressurized and heated processing to cause a portion of the organic resin film to penetrate into the through-holes 11. Therefore, this method is different from the method of filling a paste containing an organic resin by printing.

[0045] A sheet-like organic resin film has a higher viscosity than a paste containing an organic resin. In the method of filling through-hole 11 with an organic resin film, the high viscosity of the organic resin film makes the organic resin film susceptible to high shear stress between the organic resin film and conductor layer 2 formed on the inner wall of through-hole 11 when filling through-hole 11. As a result, portions of filling portion 31 with different densities and degrees of orientation are likely to be formed within through-hole 11.

[0046] At least one of the density and the degree of orientation of the filling portion 31 is likely to change in the radial direction. The difference in density of the filling portion 31 may be determined by calculating the difference in porosity. The porosity of the filling portion 31 is determined by observing the side of the filling portion 31 and calculating the difference in porosity at the center and end portions in the longitudinal direction. The difference in the degree of orientation in the filling portion 31 is preferably evaluated from the difference in the orientation of the inorganic filler. A metallurgical microscope or a digital microscope may be used to evaluate the degree of orientation of the inorganic filler. This is because using a metallurgical microscope or a digital microscope allows light to be shone on the sample to be observed and the shape based on the reflected light to be obtained.

[0047] The degree of orientation of the inorganic filler contained in the filling portion 31 may be higher on the radial side than on the radial center. The "longitudinal direction of the through hole 11" corresponds to the thickness direction of the insulating substrate 1 in the through hole 11. In the case of Figure 1, the "radial direction of the through hole 11" corresponds to the direction perpendicular to the longitudinal direction of the through hole 11.

[0048] The shear stress experienced by the organic resin film is also due to the material or surface roughness of each of the following components. The surface 1a of the insulating substrate 1, the portion immediately above the through-hole 11, and the surface of the conductor layer 2 disposed on the surface 1a of the insulating substrate 1 or the surface of the conductor layer 2 within the through-hole 11 are made of different materials. The surface 1a of the insulating substrate 1, the portion immediately above the through-hole 11, and the surface of the conductor layer 2 disposed on the surface 1a of the insulating substrate 1 or the surface of the conductor layer 2 within the through-hole 11 may have different surface roughnesses.

[0049] The reason why the portion 11a directly above the through-hole 11 is described as being made of a different material from the surface 1a of the insulating substrate 1 and the surface of the conductor layer 2 is that the portion 11a directly above the through-hole 11 is a space where no components are present during the manufacturing process. Therefore, shear stress is generally unlikely to act on the organic resin layer 3 directly above the through-hole 11. On the other hand, since the conductor layer 2 is located inside the through-hole 11, the shear stress on the organic resin layer 3 mainly depends on the surface condition of the inner wall of the conductor layer 2.

[0050] Next, a method for manufacturing a wiring board according to the present disclosure will be described. The method for manufacturing a wiring board according to one embodiment of the present disclosure includes the following steps (a) to (e): (a) preparing an insulating substrate having through holes; (b) forming a conductor layer on at least a portion of the inner wall surfaces of the through holes and the surface of the insulating substrate; (c) covering the insulating substrate and the conductor layer with an organic resin film; (d) subjecting the substrate to a heat and pressure treatment to fill a portion of the organic resin film into the through holes; and (e) curing the organic resin film to form an organic resin layer.

[0051] First, in step (a), an insulating substrate 1 is prepared having a through-hole 11. The insulating substrate 1 is as described above, and a detailed description thereof will be omitted.

[0052] Next, in step (b), a conductor layer 2 is formed on the inner wall surfaces of the through holes 11 and at least a portion of the surface of the insulating substrate 1. The conductor layer 2 is not limited to any particular material as long as it is a conductor such as a metal, as described above. Specifically, the conductor layer 2 is formed of a metal foil such as copper foil or a metal plating such as copper plating. Specifically, the conductor layer 2 is formed by attaching a metal foil such as copper foil or by depositing a metal such as copper by plating.

[0053] Next, in step (c), an organic resin film is coated on the insulating substrate 1 and the conductor layer 2. The organic resin film becomes the organic resin layer 3 after being cured in step (e) described below. Therefore, the resin forming the organic resin film may be any of the organic resins described above, and a detailed description thereof will be omitted.

[0054] The size and shape of the organic resin film are not limited. For example, when viewed in plan, the shape of the organic resin film may be substantially the same as the shape of the insulating substrate 1. If the shape of the organic resin film is substantially the same as the shape of the insulating substrate 1, the same organic resin film will be present in every region on the insulating substrate 1, and no unevenness in the dielectric constant will occur. As a result, impedance matching will be easier.

[0055] Furthermore, the organic resin film has a frequency dependency of complex melt viscosity at 110°C of 1 x 10 in a frequency range of 0.1 rad / s or more and 100 rad / s or less. ４ Pas or more 1x10 ６ An organic resin film having a complex melt viscosity of not more than Pas may be used. By using such an organic resin film, the through-hole 11 can be stably filled with resin.

[0056] Next, in step (d), the organic resin film is subjected to a heating and pressurizing treatment to fill a portion of the organic resin film into the through-hole 11. The heating temperature is set appropriately depending on the organic resin film used, and may be, for example, a temperature at which the organic resin film is softened and a portion of the softened organic resin film can penetrate into the through-hole 11. The pressure condition may be, for example, 1.0 MPa or more and 5.0 MPa or less.

[0057] Specifically, if the minimum melting temperature of the organic resin film is a°C, the film may be heated within a range of a°C ±20°C. By heating at such a temperature, the softened organic resin film is less likely to flow out to the outer periphery of the insulating substrate 1 even when pressure is applied. Furthermore, the softened organic resin film can be filled into the through-holes 11 with almost no voids. As a result, the dielectric constant tends to be uniform, and loss due to reflection can be reduced.

[0058] The heating and pressurizing treatment may be performed under a reduced pressure atmosphere. By performing the heating and pressurizing treatment under a reduced pressure atmosphere, when the organic resin film is filled from both sides, voids are less likely to occur in the organic resin film filled in the through-holes 11. As a result, the dielectric constant can be made constant, and reflection is less likely to occur.

[0059] Finally, in step (e), the organic resin film is cured to form the organic resin layer 3. The curing method is appropriately selected depending on the organic resin film used. When a thermosetting organic resin film is used, it is cured by a heat treatment. When a thermoplastic organic resin film is used, it is heated to fill the through-holes 11, and then the temperature is lowered to room temperature to be cured.

[0060] This process reduces the formation of voids when filling the through-holes with resin, resulting in a wiring board according to an embodiment of the present disclosure in which the resin-filled through-holes function as waveguides with low dielectric loss.

[0061] The wiring board specifically obtained by the above process was confirmed by analysis that when the portion of the organic resin layer excluding the filling portion was used as the covering portion, the filling portion and the covering portion were formed of the same material. There was no interface between the covering portion and the filling portion. That is, when the portion of the covering portion located on the through hole was used as the hole covering portion, there was no interface between the hole covering portion and the filling portion. Furthermore, in the produced wiring board, a portion of the filling portion protruded from the surface of the insulating substrate opposite the surface on which the organic resin layer was disposed. Among the multiple wiring boards produced, it was found that in all through holes formed on the surface of the wiring board, a portion of the filling portion protruded from the surface of the insulating substrate opposite the surface on which the organic resin layer was disposed.

[0062] The wiring board according to the present disclosure is not limited to the above-described embodiment. In the wiring board according to the above-described embodiment, the organic resin layer 3 is located on one surface of the insulating substrate 1. However, as in the wiring board according to another embodiment shown in FIG. 2 , the organic resin layer 3 may be located on both surfaces of the insulating substrate 1.

[0063] 2, a wiring board having organic resin layers 3 on both sides of an insulating substrate 1 may be subjected to a heat and pressure treatment after both sides of the insulating substrate 1 are covered with an organic resin film. Alternatively, one side of the insulating substrate 1 may be covered with an organic resin film and subjected to a heat and pressure treatment, and then the other side may be covered with an organic resin film and subjected to a heat and pressure treatment.

[0064] Although the embodiments of the present disclosure have been described above, the invention according to the present disclosure is not limited to the above-described embodiments, and various modifications and improvements are possible within the scope of the present disclosure as shown in (1) and (6) below.

[0065] (1) A wiring board according to the present disclosure includes an insulating substrate having a through hole, a conductor layer located on the inner wall surface of the through hole and on at least a portion of the surface of the insulating substrate, and an organic resin layer covering the insulating substrate and the conductor layer. The organic resin layer has a filling portion located within the through hole.

[0066] Regarding the embodiments of the present disclosure, the following embodiments (2) to (5) and (7) to (10) are further disclosed.

[0067] (2) In the wiring board described in (1) above, when the portion of the organic resin layer excluding the filling portion is defined as the covering portion, the filling portion and the covering portion are formed of the same material. (3) In the wiring board described in (2) above, there is no interface between the covering portion and the filling portion. (4) In the wiring board described in (2) or (3) above, when the portion of the covering portion located above the through hole is defined as the hole covering portion, there is no interface between the hole covering portion and the filling portion. (5) In the wiring board described in any of (1) to (4) above, a portion of the filling portion protrudes from the surface of the insulating substrate.

[0068] (6) A method for manufacturing a wiring board according to the present disclosure includes the steps of preparing an insulating substrate having through holes, forming a conductor layer on the inner wall surfaces of the through holes and on at least a portion of the surface of the insulating substrate, covering the insulating substrate and the conductor layer with an organic resin film, subjecting the resulting substrate to a heating and pressure treatment to fill a portion of the organic resin film into the through holes, and curing the organic resin film to form an organic resin layer.

[0069] (7) In the manufacturing method described in (6) above, the shape of the organic resin film and the shape of the insulating substrate are substantially the same when viewed in plan. (8) In the manufacturing method described in (6) or (7) above, the frequency dependence of the complex melt viscosity of the organic resin film at 110°C is 1 x 10 in a frequency range of 0.1 rad / s to 100 rad / s. ４ Pas or more 1x10 ６The complex melt viscosity is 0.05 Pa s or less. (9) In the manufacturing method according to any one of (6) to (8) above, when the minimum melting temperature of the organic resin film is a°C, the heating and pressure treatment is carried out in the range of a°C ± 20°C. (10) In the manufacturing method according to any one of (6) to (9) above, the heating and pressure treatment is carried out in a reduced pressure atmosphere.

[0070] REFERENCE SIGNS LIST 1 insulating substrate 11 through hole 2 conductor layer 3 organic resin layer 31 filling portion 32 covering portion

Claims

1. An insulating substrate having through holes; A conductor layer located on at least a part of the inner wall surface of the through holes and the surface of the insulating substrate; An organic resin layer covering the insulating substrate and the conductor layer; comprising: The organic resin layer has a filling portion located in the through holes; A wiring board.

2. The wiring board according to claim 1, wherein when a portion of the organic resin layer excluding the filling portion is defined as a covering portion, the filling portion and the covering portion are formed of the same material.

3. The wiring board according to claim 2, wherein there is no interface between the covering portion and the filling portion.

4. The wiring board according to claim 2 or 3, wherein when a portion of the covering portion located on the through holes is defined as a hole covering portion, there is no interface between the hole covering portion and the filling portion.

5. The wiring board according to claim 1 or 2, wherein a part of the filling portion protrudes from the surface of the insulating substrate.

6. A step of preparing an insulating substrate having through holes; A step of forming a conductor layer on at least a part of the inner wall surface of the through holes and the surface of the insulating substrate; A step of covering the insulating substrate and the conductor layer with an organic resin film; A step of subjecting to heat and pressure treatment to fill a part of the organic resin film into the through holes; A step of curing the organic resin film to form an organic resin layer; A method for manufacturing a wiring board, comprising:

7. The method for manufacturing a wiring board according to claim 6, wherein when viewed in plan, the shape of the organic resin film and the shape of the insulating substrate are substantially the same.

8. The frequency dependence of the complex melt viscosity of the organic resin film at 110 °C is in the frequency range of 0.1 rad / s or more and 100 rad / s or less, and is a complex melt viscosity of 1 × 10 ４ Pa·s or more and 1 × 10 ６ Pa·s or less. The method for manufacturing a wiring board according to claim 6 or 7.

9. The method for manufacturing a wiring board according to claim 6 or 7, wherein when the minimum melting temperature of the organic resin film is a °C, the heat and pressure treatment is performed in the range of a °C ± 20 °C.

10. The method for manufacturing a wiring board according to claim 6 or 7, wherein the heat and pressure treatment is performed in a reduced pressure atmosphere.