Wiring board, electronic module, and method for manufacturing wiring board

Abstract

In the present invention, a first insulating film is provided with a through hole which penetrates the first insulating film in the thickness direction. A first conductor pattern is disposed on a first surface, which is one of the surfaces of the first insulating film. The first conductor pattern closes an opening on the first surface-side of the through hole. A first connection conductor is disposed in the through hole. The first connection conductor is connected to the first conductor pattern, and the thickness-direction dimension of the first connection conductor is smaller than the thickness direction dimension of the first insulating film. The metal element for which the content thereof in the first conductor pattern is greatest and the metal element for which the content thereof in the first connection conductor is the greatest are the same.

Description

Wiring board, electronic module, and method for manufacturing wiring board

[0001] The present invention relates to a wiring board, an electronic module, and a method for manufacturing a wiring board.

[0002] Various wiring boards for mounting electronic components are known (Patent Documents 1, 2, and 3). The wiring boards disclosed in Patent Documents 1 and 2 include an inner layer conductor pattern on a board and a covering layer (insulating layer) covering the inner layer conductor pattern. An opening is provided in the covering layer, and a portion of the surface of the inner layer conductor pattern is exposed at the bottom of the opening. The surface of the inner layer conductor pattern exposed in the opening is covered with a surface treatment portion (surface layer). The portion of the inner layer conductor pattern exposed in the opening is used as a terminal for mounting an electronic component. The surface treatment portion functions as a connecting conductor for connecting solder bumps or the like of the electronic component to the inner layer conductor pattern.

[0003] The inner layer conductor pattern disclosed in Patent Document 1 uses copper foil, and the surface treatment uses solder, alloy, gold, silver, nickel, etc. The inner layer conductor pattern disclosed in Patent Document 2 uses a metal mainly composed of copper, and the surface layer uses Ni-Au plating or Sn (solder) plating. The surface layer protects the inner layer conductor pattern underneath.

[0004] In the wiring board disclosed in Patent Document 3, a connecting conductor is filled in a through hole facing a first resin layer. The connecting conductor is connected to an inner layer conductor pattern on a lower layer. A second resin layer is disposed on the first resin layer, and an opening is provided in the second resin layer to expose the connecting conductor. The connecting conductor exposed in the opening is used as a terminal for mounting an electronic component. A melting point variable bonding material is used for the connecting conductor.

[0005] JP 2005-235981 A JP 2005-244108 A International Publication No. 2015 / 170539

[0006] In the wiring boards disclosed in Patent Documents 1, 2, and 3, stress is likely to concentrate at the interface between the inner layer conductor pattern and the connecting conductor due to geometric discontinuity. Furthermore, the inner layer conductor pattern and the connecting conductor are formed of different materials. Therefore, cracks are likely to occur at the interface between the inner layer conductor pattern and the connecting conductor due to stress concentration. An object of the present invention is to provide a wiring board in which cracks are less likely to occur at the interface between the conductor pattern and the connecting conductor. Another object of the present invention is to provide an electronic module using this wiring board. Yet another object of the present invention is to provide a method for manufacturing this wiring board.

[0007] According to one aspect of the present invention, there is provided a wiring substrate comprising: a first insulating film having a through hole penetrating through in the thickness direction; a first conductor pattern disposed on a first surface which is one surface of the first insulating film and covering an opening of the through hole on the first surface side; and a first connecting conductor disposed in the through hole and connected to the first conductor pattern, the first connecting conductor having a dimension in the thickness direction smaller than the dimension in the thickness direction of the first insulating film, wherein the metal element having the largest content in the first conductor pattern is the same as the metal element having the largest content in the first connecting conductor.

[0008] According to another aspect of the present invention, there is provided an electronic module comprising: the wiring board; and an electronic component mounted on the wiring board via solder bumps, the solder bumps being connected to the connection conductors.

[0009] According to yet another aspect of the present invention, there is provided a method for manufacturing a wiring board, comprising the steps of: preparing a first insulating film having a first conductor pattern formed on one of its first surfaces; forming a through hole that reaches the first conductor pattern from a surface of the first insulating film opposite the first surface; and forming a first connecting conductor in the through hole by plating using the first conductor pattern as a seed, wherein the metal element with the largest content in the first conductor pattern is the same as the metal element with the largest content in the first connecting conductor, and the dimension of the first connecting conductor in the thickness direction is smaller than the dimension of the first insulating film on the first conductor pattern in the thickness direction.

[0010] Since the metal element with the highest content in the conductor pattern and the metal element with the highest content in the connecting conductor are the same, the discontinuity of the material at the interface between them is reduced, which makes it possible to suppress the occurrence of cracks and peeling due to stress concentration at the interface between the conductor pattern and the connecting conductor.

[0011] FIG. 1 is a cross-sectional view of a wiring board according to a first embodiment. FIGS. 2A and 2B are cross-sectional views of the wiring board according to the first embodiment at intermediate stages of manufacture. FIG. 3 is a cross-sectional view of a wiring board according to a second embodiment. FIG. 4 is a cross-sectional view of a wiring board for explaining the excellent effects of the second embodiment. FIG. 5 is a cross-sectional view of an electronic module according to a third embodiment. FIG. 6 is a cross-sectional view of a wiring board according to a fourth embodiment. FIG. 7 is a cross-sectional view of a wiring board according to a modified example of the fourth embodiment. FIG. 8 is a cross-sectional view of a wiring board according to another modified example of the fourth embodiment. FIG. 9 is a cross-sectional view of a wiring board according to yet another modified example of the fourth embodiment. FIG. 10 is a cross-sectional view of a wiring board according to a fifth embodiment. FIG. 11 is a cross-sectional view of a wiring board according to a modified example of the fifth embodiment.

[0012] 1 to 2B, a wiring board according to a first embodiment will be described. FIG. 1 is a cross-sectional view of a wiring board 50 according to the first embodiment. The wiring board 50 according to the first embodiment includes a first insulating film 21 having a through hole 21A formed therein, a first conductor pattern 20, a first connecting conductor 22 disposed in the through hole 21A, and a surface treatment layer 23 disposed on the surface of the first connecting conductor 22. Although a plurality of through holes 21A may be provided, for example, FIG. 1 shows only one through hole 21A.

[0013] The first conductor pattern 20 is disposed on a first surface 21B, which is one surface of the first insulating film 21. The first conductor pattern 20 covers the opening of the through-hole 21A on the first surface 21B side. Hereinafter, the surface of each component facing away from the first surface 21B will be referred to as the upper surface. The direction perpendicular to the first surface 21B will also be referred to as the thickness direction.

[0014] The side surfaces of the through hole 21A are inclined so that the area of ​​the planar cross section (cross section parallel to the first surface 21B) of the through hole 21A increases with increasing distance upward from the first conductor pattern 20. That is, the through hole 21A has an inverse tapered shape that narrows downward. When the first insulating film 21 is viewed from above (hereinafter, sometimes simply referred to as "in a planar view"), the through hole 21A is included in the first conductor pattern 20.

[0015] The first connecting conductor 22 disposed in the through hole 21A is in contact with the first conductor pattern 20. The first connecting conductor 22 and the first conductor pattern 20 are formed of the same metal, for example, copper.

[0016] The surface treatment layer 23 formed on the upper surface of the first connecting conductor 22 contains at least one material selected from the group consisting of Ni, Au, solder, and flux. ２ and the height h to the upper surface of the surface treatment layer 23 ３ is the height h to the top surface of the first insulating film 21 １ Therefore, a recess 51 appears on the upper surface of the wiring substrate 50. The surface treatment layer 23 is exposed at the bottom of the recess 51.

[0017] Next, a method for manufacturing the wiring substrate 50 according to the first embodiment will be described with reference to Figures 2A and 2B. Figures 2A and 2B are cross-sectional views of the wiring substrate 50 according to the second embodiment at intermediate stages in the manufacturing process.

[0018] 2A , the conductor foil of the resin sheet with conductor foil is patterned to form a laminated structure having a first insulating film 21 and a first conductor pattern 20. For example, copper foil is used as the conductor foil, and a sheet containing thermoplastic polyimide (PI) as the main material is used as the resin sheet. Materials such as polyetheretherketone (PEEK), polyetherimide (PEI), polyphenylene sulfide (PPS), and liquid crystal polymer (LCP) may also be used as the resin sheet material.

[0019] 2B , through holes 21A are formed in the first insulating film 21 from the surface opposite to the surface on which the first conductor pattern 20 is disposed, and reach the first conductor pattern 20. A laser processing method using, for example, a carbon dioxide laser can be used to form the through holes 21A. This laser processing is performed under conditions that cause little damage to the first conductor pattern 20.

[0020] 1, the first conductive pattern 20 is used as a seed to plate copper on the first conductive pattern 20 exposed in the through hole 21A, thereby forming the first connecting conductor 22. Electroless plating or electrolytic plating is used for this plating. The resin sheet constituting the first insulating film 21 is then pressurized and heated to harden the resin sheet.

[0021] The wiring board 50 according to the first embodiment is used, for example, as the top layer of a mounting board for mounting electronic components having solder bumps or the like. The solder bumps of the electronic components are connected to the first connecting conductors 22 via the surface treatment layer 23, thereby mounting the electronic components on the wiring board 50. The surface treatment layer 23 has the function of protecting the surfaces of the first connecting conductors 22 and the function of improving mountability when mounting the electronic components.

[0022] Next, the advantageous effects of the first embodiment will be described. Because the interface between the first connecting conductor 22 and the first conductor pattern 20 is geometrically discontinuous, stress tends to concentrate at the interface between the first connecting conductor 22 and the first conductor pattern 20 due to the difference in thermal expansion coefficient between the wiring board 50 and the electronic component. For example, if copper is used for the first conductor pattern 20 and solder is used for the first connecting conductor 22, discontinuity in the material also occurs at the interface between the two. When stress concentrates at the interface where the material discontinuity occurs, cracks and peeling are likely to occur.

[0023] In the first embodiment, since the first conductor pattern 20 and the first connecting conductor 22 are both made of copper, there is no discontinuity in the material at the interface between them. This increases the mechanical strength of the interface between the first conductor pattern 20 and the first connecting conductor 22. As a result, cracks, peeling, etc. are less likely to occur at the interface between them.

[0024] If solder paste is used for the first connecting conductor 22, a phenomenon occurs in which the metal constituting the first conductor pattern 20 dissolves into the solder (sometimes called "solder erosion"). In the first embodiment, the first connecting conductor 22 and the first conductor pattern 20 are formed from the same metal, so solder erosion does not occur.

[0025] Furthermore, in the first embodiment, a recess 51 is generated in the region where the first connecting conductor 22 is disposed. After the through hole 21A is formed, the first connecting conductor 22 is filled in a portion below the through hole 21A, so that the centers of the through hole 21A and the first connecting conductor 22 substantially coincide in a plan view. When mounting an electronic component on the wiring substrate 50, the solder bumps of the electronic component are positioned in the recess 51 generated at the position of the through hole 21A. As a result, the first connecting conductor 22 and the solder bumps of the electronic component can be positioned with high precision.

[0026] In order to prevent cracks and peeling from occurring at the interface between the first conductor pattern 20 and the first connecting conductor 22, the height h of the first connecting conductor 22 is set to 1 / 2 mm. ２ is preferably set to be equal to or greater than the thickness of the first conductive pattern 20. In addition, in order to facilitate positioning when mounting electronic components, the height h ２ is the height h of the first insulating film 21. １ The total height h of the first connection conductor 22 and the surface treatment layer 23 is preferably 90% or less. ２ is the height h of the first insulating film 21 １ It is preferable that it is less than 1000 kJ / s.

[0027] Next, a wiring board according to a modification of the first embodiment will be described. In the first embodiment, copper is used for the first conductor pattern 20 and the first connecting conductor 22, but other metals may be used for the first conductor pattern 20 and the first connecting conductor 22. For example, silver, gold, etc. may be used.

[0028] Alternatively, an alloy containing copper, silver, or gold as a main component may be used for the first conductive pattern 20 and the first connecting conductor 22. When an alloy is used for the first conductive pattern 20 and the first connecting conductor 22, it is preferable that the constituent elements of the alloy are the same, and it is even more preferable that the ratio of the contents of the constituent elements is the same.

[0029] Furthermore, even if not all of the constituent elements of the alloy are the same, as long as the main constituent elements are the same, discontinuity in the material is alleviated and sufficient mechanical strength can be ensured. In order to ensure sufficient mechanical strength, it is preferable that the metal element with the largest content in the first conductor pattern 20 is the same as the metal element with the largest content in the first connecting conductor 22.

[0030] In the first embodiment, the first connecting conductor 22 is formed by plating, but the first connecting conductor 22 may be formed by other methods. For example, a conductive paste may be placed in the through hole 21A and then cured to form the first connecting conductor 22. When this method is used, binder resin remains in the first connecting conductor 22. In this case, it is preferable to use the same metal for the conductive particles contained in the first connecting conductor 22 and the first conductor pattern 20.

[0031] Furthermore, compared to using conductive paste, using plating allows the first connection conductor 22 to be filled into the lower portion of the through hole 21A with good reproducibility even when the size of the through hole 21A in a plan view is small. The decision of whether to use plating or conductive paste should be based on the size of the through hole 21A, etc. Furthermore, using plating allows the first connection conductor 22 to be formed from a metal that does not contain binder resin, etc. When the wiring substrate 50 is used as the top layer of a mounting substrate, the thickness of the first insulating film 21 is approximately 40 μm at most, so using plating does not significantly increase costs compared to using conductive paste. [Second Example] Next, a wiring substrate according to a second example will be described with reference to FIGS. 3 and 4. Below, a description of the components common to the wiring substrate 50 according to the first example described with reference to FIGS. 1, 2A, and 2B will be omitted.

[0032] 3 is a cross-sectional view of a wiring board 50 according to the second embodiment. The wiring board 50 according to the second embodiment includes an underlying substrate 10, a first conductor pattern 20, a first insulating film 21, a first connecting conductor 22, and a surface treatment layer 23. The configurations of the first conductor pattern 20, the first insulating film 21, the first connecting conductor 22, and the surface treatment layer 23 are the same as those of the wiring board 50 according to the first embodiment ( FIG. 1 ). The first insulating film 21 is disposed on the upper surface of the underlying substrate 10 with the first surface 21B of the first insulating film 21 facing the underlying substrate 10. The first conductor pattern 20 is disposed between the underlying substrate 10 and the first insulating film 21. The wiring board 50 according to the second embodiment is used, for example, as a mounting substrate for mounting electronic components having solder bumps or the like.

[0033] Next, a method for manufacturing a wiring board 50 according to the second embodiment will be described. The first insulating film 21 is bonded to the base substrate 10, with the first surface 21B of the first insulating film 21, which has the first conductor pattern 20 and the first connecting conductor 22 formed thereon, facing the upper surface of the base substrate 10, which is a resin sheet or the like. With the first insulating film 21 bonded to the base substrate 10, the laminate including the base substrate 10, the first conductor pattern 20, and the first insulating film 21 is heated and pressurized to form an integrated laminate. The surface treatment layer 23 may be formed after this heat treatment.

[0034] Next, the advantageous effects of the second embodiment will be described. As in the first embodiment, the second embodiment also increases the mechanical strength of the interface between the first conductor pattern 20 and the first connecting conductor 22, making it less likely that cracks or peeling will occur at the interface. When mounting an electronic component on the wiring substrate 50, the solder bumps of the electronic component are positioned in the depressions 51 formed at the positions of the through holes 21A. As a result, the first connecting conductor 22 and the solder bumps of the electronic component can be positioned with high precision.

[0035] Next, another excellent effect of the second embodiment will be described with reference to FIG. 4 . FIG. 4 is a cross-sectional view of a wiring board 50 illustrating another excellent effect of the second embodiment. When mounting electronic components on the wiring board 50, solder paste 30 may be filled into recesses 51 formed on the surface of the wiring board 50. In the second embodiment, the side surfaces of the through holes 21A are inclined so that the area of ​​the planar cross section of the through holes 21A increases with increasing distance from the first conductor pattern 20 upward. This provides the excellent effect of reducing the likelihood of air voids being generated when filling the recesses 51 with solder paste 30.

[0036] Third Embodiment Next, an electronic module according to a third embodiment will be described with reference to Fig. 5. The electronic module according to the third embodiment includes the wiring board 50 according to the second embodiment (Fig. 3) and electronic components mounted on this wiring board 50.

[0037] 5 is a cross-sectional view of an electronic module according to a third embodiment. A wiring substrate 50 is provided with a plurality of first connection conductors 22 and a surface treatment layer 23. Each of a plurality of terminals 41 of an electronic component 40 is connected to a first conductor pattern 20 via a solder bump 45, the surface treatment layer 23, and the first connection conductor 22. Portions of the plurality of solder bumps 45 on the wiring substrate 50 side are recessed into depressions 51 formed on the surface of the wiring substrate 50.

[0038] Next, the advantageous effects of the third embodiment will be described. As in the second embodiment, the third embodiment also provides the advantageous effect of preventing cracks and peeling at the interface between the first conductor pattern 20 and the first connecting conductor 22. Furthermore, since the multiple solder bumps 45 are each embedded in the recesses 51, the excellent effect of increasing the shear strength is obtained.

[0039] Fourth Embodiment Next, a wiring board according to a fourth embodiment will be described with reference to Fig. 6. Below, a description of the configuration common to the wiring board 50 according to the second embodiment described with reference to Fig. 3 will be omitted.

[0040] FIG. 6 is a cross-sectional view of a wiring board 50 according to a fourth embodiment. In the second embodiment ( FIG. 3 ), the detailed configuration of the base substrate 10 is not particularly limited. In the fourth embodiment, the base substrate 10 includes a second insulating film 11, a second conductor pattern 12, and a second connecting conductor 13. The second conductor pattern 12 is disposed on the lower surface of the second insulating film 11. A via hole penetrating the second insulating film 11 in the thickness direction is provided. A second connecting conductor 13 is filled in this via hole. The second connecting conductor 13 connects the first conductor pattern 20 and the second conductor pattern 12. The second connecting conductor 13 is formed of the same conductive material as the second conductor pattern 12, for example, copper. The second insulating film 11 and the first insulating film 21 may be formed of the same insulating material or different insulating materials.

[0041] Next, a method for manufacturing the wiring board 50 according to the fourth embodiment will be described. First, the base substrate 10 is fabricated in the same manner as the method for manufacturing the wiring board 50 according to the first embodiment described with reference to Figures 2A and 2B. In the step of filling the second connection conductors 13, plating is performed until the surfaces thereof become substantially flush with the surface of the second insulating film 11. At this stage, no heat treatment has been performed yet.

[0042] The first insulating film 21 provided with the first conductor patterns 20 and the first connecting conductors 22 before the heat treatment is attached to the base substrate 10 before the heat treatment, and then heated and pressed to form an integrated laminate. The surface treatment layer 23 is preferably formed after the heat treatment.

[0043] Next, the excellent effects of Example 4 will be described. As in Example 2, Example 4 can also suppress the occurrence of cracks and peeling at the interface between the first conductor pattern 20 and the first connecting conductor 22. Furthermore, it can also suppress the occurrence of cracks and peeling at the interface between the second conductor pattern 12 and the second connecting conductor 13.

[0044] Next, a modification of the fourth embodiment will be described. In the fourth embodiment, copper is used for the second conductor pattern 12 and the second connecting conductor 13, but other metals may be used for the second conductor pattern 12 and the second connecting conductor 13. For example, silver, gold, etc. may be used.

[0045] Alternatively, an alloy containing copper, silver, or gold as a main component may be used for the second conductive pattern 12 and the second connecting conductor 13. When an alloy is used for the second conductive pattern 12 and the second connecting conductor 13, it is preferable that the constituent elements of the alloy are the same, and it is more preferable that the ratio of the contents of the constituent elements is the same.

[0046] Furthermore, even if not all of the constituent elements of the alloy are the same, as long as the main constituent elements are the same, discontinuity in the material is alleviated and sufficient mechanical strength can be ensured. In order to ensure sufficient mechanical strength, it is preferable that the metal element with the largest content in the second conductor pattern 12 is the same as the metal element with the largest content in the second connecting conductor 13.

[0047] Next, a wiring board according to a modification of the fourth embodiment will be described with reference to FIG. 7. FIG. 7 is a cross-sectional view of a wiring board 50 according to a modification of the fourth embodiment. In the fourth embodiment (FIG. 6), the base substrate 10 has a single-layer wiring structure, but in the modification shown in FIG. 7, the base substrate 10 has a multi-layer wiring structure. Each layer of the multi-layer wiring structure includes a second insulating film 11, a second conductor pattern 12, and a second connecting conductor 13. As in this modification, the base substrate 10 may have a multi-layer wiring structure.

[0048] Next, a wiring board according to another modification of the fourth embodiment will be described with reference to Fig. 8. Fig. 8 is a cross-sectional view of a wiring board 50 according to this modification. In the modification shown in Fig. 7, the second connecting conductor 13 is formed by plating using the same conductive material as the second conductor pattern 12. In contrast, in the modification shown in Fig. 8, the second connecting conductor 13 is formed by hardening a conductive paste. The conductive paste may be copper paste, silver paste, gold paste, solder paste, or the like.

[0049] When a conductive paste is used for the second connecting conductor 13 as in this modified example, the electrical connectivity at the interface between the second connecting conductor 13 and the second conductor pattern 12 that is adhered thereon by pressure and heat can be improved compared to when the second connecting conductor 13 is formed by plating as in the fourth embodiment.

[0050] Next, a wiring board according to yet another modification of the fourth embodiment will be described with reference to Fig. 9. Fig. 9 is a cross-sectional view of a wiring board 50 according to this modification. In this modification, the second connection conductor 13 is composed of a first portion 13A on the side farther from the first insulating film 21 (lower side) and a second portion 13B on the side closer to the first insulating film 21 (upper side). The first portion 13A is formed of the same conductive material as the second conductor pattern 12, as in the modification of the fourth embodiment shown in Fig. 7, and the second portion 13B is formed of a conductive material obtained by hardening a conductive paste, as in the modification shown in Fig. 8.

[0051] In this modification, it is possible to improve the electrical connectivity between the first portion 13A on the lower side of the second connecting conductor 13 and the second conductor pattern 12, and between the second portion 13B on the upper side of the second connecting conductor 13 and the second conductor pattern 12. Since the amount of conductive paste used is smaller than in the modification shown in Fig. 8, the amount of gas generated when the conductive paste hardens is reduced. Furthermore, since the depth of the recess to be filled with the conductive paste is shallower than in the modification shown in Fig. 8, it is possible to reduce the diameter and pitch of the second connecting conductors 13.

[0052] Fifth Embodiment Next, a wiring board according to a fifth embodiment will be described with reference to Fig. 10. Below, a description of the configuration common to the wiring board 50 according to the second embodiment described with reference to Fig. 3 will be omitted.

[0053] 10 is a cross-sectional view of a wiring board 50 according to the fifth embodiment. In the second embodiment (FIG. 3), the upper surface of the first connecting conductor 22 is substantially flat. In contrast, in the fifth embodiment, the upper surface of the first connecting conductor 22 has a concave shape that curves downward. In other words, the center of the upper surface is lower than the outer periphery. When the upper surface of the first conductor pattern 20 is used as the height reference, the height h to the highest point on the upper surface of the first connecting conductor 22 is ２ is the height h １ Such a shape of the upper surface of the first connecting conductor 22 is obtained by adjusting the plating conditions. The surface treatment layer 23 covers the curved upper surface of the first connecting conductor 22 with a substantially uniform thickness.

[0054] Next, the excellent effects of the fifth embodiment will be described. As with the second embodiment ( FIG. 1 ), the fifth embodiment also provides the excellent effect of preventing cracks and peeling at the interface between the first conductor pattern 20 and the first connecting conductor 22. Furthermore, in the fifth embodiment, when mounting an electronic component with solder balls on the wiring board 50, the solder balls on the electronic component are positioned at the lowest position on the upper surface of the first connecting conductor 22, thereby stabilizing the position of the electronic component and improving positional accuracy during mounting.

[0055] Next, a wiring board according to a modification of the fifth embodiment will be described with reference to FIG. 11. FIG. 11 is a cross-sectional view of a wiring board 50 according to a modification of the fifth embodiment. In the fifth embodiment (FIG. 10), the upper surface of the first connecting conductor 22 is curved downward, but in the modification shown in FIG. 11, the upper surface of the first connecting conductor 22 has a convex shape that curves upward. In other words, when the upper surface of the first conductor pattern 20 is used as the height reference, the height of the central part of the first connecting conductor 22 is higher than the height of the outer periphery. When the upper surface of the first conductor pattern 20 is used as the height reference, the height h to the highest point on the upper surface of the first connecting conductor 22 is ２ is the height h １ Such a shape can be achieved by adjusting plating conditions, surface treatment, etc.

[0056] In this modification, when an electronic component with a solder ball is mounted on the wiring board 50, the solder ball provided on the electronic component comes into contact at a point with the highest position of the first connecting conductor 22 or the surface treatment layer 23. This provides the excellent effect of improving the connectivity between the solder ball and the first connecting conductor 22.

[0057] The above-described embodiments are merely examples, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. Similar effects resulting from similar configurations of multiple embodiments will not be mentioned sequentially for each embodiment. Furthermore, the present invention is not limited to the above-described embodiments. For example, it will be obvious to those skilled in the art that various modifications, improvements, combinations, etc. are possible.

[0058] REFERENCE SIGNS LIST 10 Underlying substrate 11 Second insulating film 12 Second conductive pattern 13 Second connecting conductor 13A First portion of second connecting conductor 13B Second portion of second connecting conductor 20 First conductive pattern 21 First insulating film 21A Through hole 21B First surface 22 First connecting conductor 23 Surface treatment layer 30 Solder paste 40 Electronic component 41 Terminal 45 Solder bump 50 Wiring substrate 51 Recess

Claims

1. a first insulating film having a through hole penetrating in a thickness direction; a first conductor pattern disposed on a first surface that is one surface of the first insulating film and covering an opening of the through hole on the first surface side; a first connection conductor disposed in the through hole, connected to the first conductor pattern, and having a dimension in a thickness direction smaller than a dimension in a thickness direction of the first insulating film; Equipped with A wiring board in which the metal element contained in the first conductor pattern at the maximum amount is the same as the metal element contained in the first connecting conductor at the maximum amount.

2. Further, a base substrate is provided, 2. The wiring board according to claim 1, wherein the first insulating film is disposed on the base substrate with the first surface facing the base substrate, and the first conductor pattern is disposed between the first insulating film and the base substrate.

3. the base substrate includes a plurality of second conductor patterns, a plurality of second insulating films, and a plurality of second connection conductors; 3. The wiring board according to claim 2, wherein the first insulating film is disposed on a surface of the uppermost second insulating film among the plurality of second insulating films.

4. 4. The wiring board according to claim 3, wherein the metal element contained in each of the plurality of second conductor patterns is the same as the metal element contained in each of the plurality of second connection conductors.

5. 4. The wiring board according to claim 3, wherein each of the plurality of second connection conductors is formed of a conductive material obtained by hardening a conductive paste, and each of the plurality of second conductor patterns is formed of a conductive material different from that of the plurality of second connection conductors.

6. 4. The wiring board according to claim 3, wherein each of the plurality of second connection conductors includes a first portion in contact with the plurality of second conductor patterns and a second portion in contact with the second conductor pattern closer to the first insulating film, the metal element having the largest content in the first portion being the same as the metal element having the largest content in the second conductor pattern with which the first portion contacts, and the second portion is formed of a conductive material obtained by hardening a conductive paste.

7. The wiring board according to claim 1 , wherein the upper surface of the first connection conductor has a concave shape with the center being lower than the outer periphery.

8. The wiring board according to claim 1 , wherein the upper surface of the first connection conductor has a convex shape with the center higher than the periphery.

9. The wiring board according to claim 1 , wherein the through hole has a shape that widens in a direction away from the first conductor pattern.

10. 7. The wiring board according to claim 1, wherein the first connection conductor and the first conductor pattern are formed from copper, silver, gold, an alloy primarily composed of copper, an alloy primarily composed of silver, or an alloy primarily composed of gold.

11. 7. The wiring board according to claim 1, further comprising a surface treatment layer on the surface of the first connection conductor, the surface treatment layer containing at least one material selected from the group consisting of Ni, Au, solder, and flux.

12. The wiring board according to any one of claims 1 to 6, an electronic component mounted on the wiring board via solder bumps; Equipped with The solder bumps are connected to the first connection conductors.

13. a first insulating film having a first conductor pattern formed on a first surface, the first insulating film being one surface of the first insulating film; forming a through hole that reaches the first conductor pattern from a surface of the first insulating film opposite to the first surface; a method for manufacturing a wiring substrate, the method comprising forming a first connection conductor in the through hole by plating using the first conductor pattern as a seed, the metal element having the largest content in the first conductor pattern is the same as the metal element having the largest content in the first connecting conductor, A method for manufacturing a wiring board, wherein the dimension in the thickness direction of the first connection conductor is smaller than the dimension in the thickness direction of the first insulating film on the first conductor pattern.