Circuit board

Abstract

A circuit board 1A comprises: an insulation layer 10 having a first main surface 10a and a second main surface 10b that face each other in the thickness direction; a first interlayer connection conductor 31 and a second interlayer connection conductor 32 provided so as to pass through the same insulation layer 10 or different insulation layers 10 in the thickness direction; a first conductor layer 21 provided to the first main surface 10a of the insulation layer 10 and connected to the first interlayer connection conductor 31; a second conductor layer 22 provided to the second main surface 10b of the insulation layer 10 and connected to the first interlayer connection conductor 31; a third conductor layer 23 provided to the first main surface 10a of the insulation layer 10 and connected to the second interlayer connection conductor 32; and a fourth conductor layer 24 provided to the second main surface 10b of the insulation layer 10 and connected to the second interlayer connection conductor 32. The first interlayer connection conductor 31 includes, in the thickness direction, a first part 31A and a second part 31B having a lower electrical conductivity than the first part 31A. One end part of the first part 31A is joined to the first conductor layer 21, and another end part of the first part 31A is joined to one end part of the second part 31B. Another end part of the second part 31B is joined to the second conductor layer 22. The second interlayer connection conductor 32 includes, in the thickness direction, a third part 32A and a fourth part 32B having a lower electrical conductivity than the third part 32A. One end part of the third part 32A is joined to the third conductor layer 23, and another end part of the third part 32A is joined to one end part of the fourth part 32B. Another end part of the fourth part 32B is joined to the fourth conductor layer 24. The relations T1<T2 and B1 / A1>B2 / A2 are satisfied, where A1 is the height of the first part 31A, B1 is the height of the second part 31B, A2 is the height of the third part 32A, B2 is the height of the fourth part 32B, T1 is the height of the first interlayer connection conductor 31, and T2 is the height of the second interlayer connection conductor 32.

Description

circuit board

[0001] The present invention relates to a circuit board.

[0002] Patent Document 1 discloses a wiring board including an insulating layer and a conductor layer formed on one main surface of the insulating layer, wherein the insulating layer has a hole with the conductor layer as a bottom and opening toward the other main surface of the insulating layer, and the hole is provided with a first via portion connected to the conductor layer and a second via portion connected to the first via portion, the first via portion includes a conductive member but does not include a resin member, the first via portion has a protrusion at the end face of the first via portion on the second via portion side that protrudes toward the second via portion, and a portion of the second via portion extends between the protrusion of the first via portion and the insulating layer and does not contact the conductor layer connected to the first via portion.

[0003] International Publication No. 2022 / 202322

[0004] Patent document 1 describes a method of forming an interlayer connecting conductor including a first via portion and a second via portion by plating a hole provided in an insulating layer with a conductor foil, and then forming a second via portion by filling the remaining part of the hole where the first via portion was formed with a conductive paste.

[0005] Furthermore, Patent Document 1 describes a method of producing a laminated substrate (hereinafter also referred to as a multilayer circuit board) by sequentially stacking insulating layers including an insulating layer with a conductor foil in which a first via portion and a second via portion are formed, and then hot pressing (collectively pressing) the obtained laminate in the stacking direction.

[0006] However, since the second via portion formed by solidifying the conductive paste has lower conductivity than the first via portion formed by filling with plated metal, if the proportion of the second via portion in the interlayer connection conductor increases, the resistance value of the entire interlayer connection conductor will increase, which may result in a deterioration in the characteristics of the substrate.

[0007] The present invention has been made to solve the above problems, and has an object to provide a circuit board that can suppress an increase in the resistance value of the entire interlayer connection conductor.

[0008] In a first aspect, the circuit board of the present invention comprises an insulating layer having a first main surface and a second main surface opposed to each other in a thickness direction, first interlayer connection conductors and second interlayer connection conductors provided through the same or different insulating layers in the thickness direction, a first conductor layer provided on the first main surface of the insulating layer and connected to the first interlayer connection conductor, a second conductor layer provided on the second main surface of the insulating layer and connected to the first interlayer connection conductor, a third conductor layer provided on the first main surface of the insulating layer and connected to the second interlayer connection conductor, and a fourth conductor layer provided on the second main surface of the insulating layer and connected to the second interlayer connection conductor. The first interlayer connection conductor includes a first portion and a second portion having a lower conductivity than the first portion in the thickness direction. One end of the first portion is joined to the first conductor layer, and the other end of the first portion is joined to one end of the second portion. The other end of the second portion is joined to the second conductor layer. The second interlayer connection conductor includes a third portion and a fourth portion having a lower conductivity than the third portion in the thickness direction. One end of the third portion is joined to the third conductor layer, and the other end of the third portion is joined to one end of the fourth portion. The other end of the fourth portion is joined to the fourth conductor layer. The height of the first portion is defined as A １ , the height of the second portion is B １ , the height of the third portion is A ２ , the height of the fourth portion is B ２ , the height of the first interlayer connection conductor is T １ , the height of the second interlayer connection conductor is T ２ When this is done, T １ <T ２ , and B １ / A １ >B ２ / A ２ The following relationship holds.

[0009] In a second aspect, the circuit board of the present invention comprises an insulating layer having a first main surface and a second main surface opposed to each other in a thickness direction, first interlayer connection conductors and third interlayer connection conductors provided penetrating the same or different insulating layers in the thickness direction, a first conductor layer provided on the first main surface of the insulating layer and connected to the first interlayer connection conductor, a second conductor layer provided on the second main surface of the insulating layer and connected to the first interlayer connection conductor, a fifth conductor layer provided on the first main surface of the insulating layer and connected to the third interlayer connection conductor, and a sixth conductor layer provided on the second main surface of the insulating layer and connected to the fourth interlayer connection conductor. The first interlayer connection conductor includes a first portion and a second portion having a lower conductivity than the first portion in the thickness direction. One end of the first portion is joined to the first conductor layer, and the other end of the first portion is joined to one end of the second portion. The other end of the second portion is joined to the second conductor layer. The third interlayer connection conductor includes, in the thickness direction, a fifth portion, a sixth portion having a lower conductivity than the fifth portion, and a seventh portion having a higher conductivity than the sixth portion. One end of the fifth portion is joined to the fifth conductor layer, and the other end of the fifth portion is joined to one end of the sixth portion. The other end of the sixth portion is joined to one end of the seventh portion. The other end of the seventh portion is joined to the sixth conductor layer. The height of the first portion is defined as A １ , the height of the second portion is B １ , the height of the fifth portion is A ３ , the height of the sixth portion is B ３ , the height of the seventh part is C ３ , the height of the first interlayer connection conductor is T １ , the height of the third interlayer connection conductor is T ３ When this is done, T １ <T ３ , and B １ / A １ >B ３ / (A ３ +C ３ ) relationship holds.

[0010] According to the present invention, it is possible to provide a circuit board capable of suppressing an increase in the resistance value of the entire interlayer connection conductor.

[0011] FIG. 1 is a cross-sectional view schematically showing an example of a circuit board of the present invention. FIG. 2A is a cross-sectional view schematically showing an example of a circuit board according to a first embodiment of the present invention. FIG. 2B is a cross-sectional view schematically showing an example of a circuit board at a position different from that shown in FIG. 2A. FIGS. 3A and 3B are schematic views for explaining a method for measuring the height of a first interlayer connection conductor, the height of a first portion, and the height of a second portion. FIGS. 4A to 4D are cross-sectional views schematically showing an example of a step of preparing a first base material filled with a first material and a second material. FIGS. 5A to 5D are cross-sectional views schematically showing an example of a step of preparing a second base material filled with a first material and a second material. FIG. 6 is a cross-sectional view schematically showing an example of a step of stacking base materials. FIG. 7 is a cross-sectional view schematically showing an example of a step of pressing the substrates together. FIG. 8A is a cross-sectional view schematically showing an example of a circuit board according to a second embodiment of the present invention. FIG. 8B is a cross-sectional view schematically showing an example of a circuit board at a position different from that shown in FIG. 8A. FIG. 9 is a cross-sectional view schematically showing an example of a circuit board according to a third embodiment of the present invention. FIG. 10 is a cross-sectional view schematically showing another example of a circuit board according to the fourth embodiment of the present invention. FIG. 11 is a cross-sectional view schematically showing an example of a circuit board according to the fifth embodiment of the present invention. FIG. 12 is a cross-sectional view schematically showing another example of a circuit board according to the fifth embodiment of the present invention. FIG. 13 is a cross-sectional view schematically showing an example of a circuit board according to the sixth embodiment of the present invention. FIG. 14A is a cross-sectional view schematically showing an example of a circuit board according to the seventh embodiment of the present invention. FIG. 14B is a cross-sectional view schematically showing an example of a circuit board at a position different from that shown in FIG. 14A. FIG. 15 is a cross-sectional view schematically showing an example of a circuit board according to the eighth embodiment of the present invention. FIG. 16 is a cross-sectional view schematically showing an example of a circuit board according to the ninth embodiment of the present invention. FIG. 17 is a cross-sectional view schematically showing another example of a circuit board according to the ninth embodiment of the present invention. FIGS. 18A, 18B, and 18C are cross-sectional views schematically showing examples of a circuit board according to the tenth embodiment of the present invention. FIG. 19A is a cross-sectional view schematically showing an example of a circuit board according to the eleventh embodiment of the present invention. Fig. 19B is a cross-sectional view schematically showing an example of a circuit board at a position different from that of Fig. 19A. Fig. 20 is a cross-sectional view schematically showing an example of a circuit module including the circuit board of the present invention.Fig. 21 is a plan view schematically showing an example of a surface layer of a circuit board. Fig. 22A, Fig. 22B, and Fig. 22C are cross-sectional views schematically showing examples of interlayer connection conductors having a constant height but different diameters.

[0012] The circuit board of the present invention will be described below. However, the present invention is not limited to the following configuration, and can be appropriately modified and applied within the scope of the present invention. A combination of two or more of the individual preferred configurations of the present invention described below also constitutes the present invention.

[0013] In this specification, terms indicating the relationship between elements (e.g., "perpendicular," "parallel," "orthogonal," etc.) and terms indicating the shapes of elements are not expressions that only express a strict meaning, but are expressions that mean that they are substantially equivalent, for example, including a difference of about a few percent. Furthermore, in this specification, "equivalent" is not an expression that means only complete equivalent, but is an expression that means that they are substantially equivalent, for example, including a difference of about a few percent.

[0014] The drawings shown below are schematic diagrams, and the dimensions, aspect ratio, and other scales may differ from those of the actual product. In the drawings, the same or equivalent parts will be designated by the same reference numerals. In addition, the same elements will be designated by the same reference numerals in each drawing, and duplicate explanations will be omitted.

[0015] FIG. 1 is a cross-sectional view schematically showing an example of the circuit board of the present invention.

[0016] The circuit board 1 shown in FIG. 1 includes an insulating layer 10 , a conductor layer 20 , and an interlayer connection conductor 30 .

[0017] In the example shown in FIG. 1 , the circuit board 1 is a multilayer circuit board including a plurality of insulating layers 10 .

[0018] The circuit board 1 may be a rigid board or a flexible board, and may have a bent portion.

[0019] In the circuit board 1, the conductor layer 20 includes a first conductor layer, a second conductor layer, a third conductor layer, and a fourth conductor layer, which will be described in each embodiment below. The conductor layer 20 may include a fifth conductor layer and a sixth conductor layer in addition to the first conductor layer, the second conductor layer, the third conductor layer, and the fourth conductor layer. Alternatively, the conductor layer 20 may include a fifth conductor layer and a sixth conductor layer instead of the third conductor layer and the fourth conductor layer. The circuit board 1 may also include conductor layers 20 other than the first conductor layer, the second conductor layer, the third conductor layer, the fourth conductor layer, the fifth conductor layer, and the sixth conductor layer.

[0020] In the circuit board 1, the interlayer connection conductors 30 include a first interlayer connection conductor and a second interlayer connection conductor, which will be described in each embodiment below. Specifically, it is sufficient that the circuit board 1 includes at least one first interlayer connection conductor and at least one second interlayer connection conductor.

[0021] The interlayer connection conductors 30 may include a third interlayer connection conductor in addition to the first and second interlayer connection conductors. Specifically, the circuit board 1 may include at least one first interlayer connection conductor, at least one second interlayer connection conductor, and at least one third interlayer connection conductor.

[0022] Alternatively, the interlayer connection conductor 30 may include a third interlayer connection conductor instead of the second interlayer connection conductor. Specifically, at least one first interlayer connection conductor and at least one third interlayer connection conductor may be included in the circuit board 1.

[0023] The circuit board 1 may include interlayer connection conductors 30 other than the first interlayer connection conductor, the second interlayer connection conductor, and the third interlayer connection conductor.

[0024] The following embodiments are merely examples, and it goes without saying that partial substitution or combination of the configurations shown in different embodiments is possible. From the second embodiment onwards, a description of the matters common to the first embodiment will be omitted, and only the differences will be described. In particular, similar effects due to similar configurations will not be mentioned in each embodiment.

[0025] Fig. 2A is a cross-sectional view schematically showing an example of the circuit board according to the first embodiment of the present invention, and Fig. 2B is a cross-sectional view schematically showing the example of the circuit board at a position different from that shown in Fig. 2A.

[0026] Although the overall configuration is not shown in Figures 2A and 2B, the circuit board 1A includes an insulating layer 10, a first conductor layer 21, a second conductor layer 22, a third conductor layer 23, a fourth conductor layer 24, a first interlayer connection conductor 31, and a second interlayer connection conductor 32.

[0027] The insulating layer 10 has a first main surface 10a and a second main surface 10b that face each other in the thickness direction (the vertical direction in FIGS. 2A and 2B).

[0028] The insulating layer 10 is, for example, a resin insulating layer containing a resin as a main component. When the first conductor layer 21 or the second conductor layer 22 is a signal line, or when the third conductor layer 23 or the fourth conductor layer 24 is a signal line, loss during signal transmission can be reduced by forming the insulating layer 10 from a resin having a low dielectric constant.

[0029] Alternatively, the insulating layer 10 may be a ceramic insulating layer containing ceramic as a main component. When the first conductor layer 21 or the second conductor layer 22 is an antenna electrode, or when the third conductor layer 23 or the fourth conductor layer 24 is an antenna electrode, the insulating layer 10 is made of ceramic having a high dielectric constant, thereby enabling radiation or reception in a wide band.

[0030] The resin constituting the resin insulation layer may be a thermosetting resin or a thermoplastic resin, but is preferably a thermoplastic resin. When the resin insulation layer is made of a thermoplastic resin, multiple resin sheets on which conductor layers are formed can be stacked and collectively pressure-bonded (collectively pressed) by heat treatment.

[0031] Examples of the thermosetting resin include epoxy resin, phenol resin, polyimide resin or modified resin thereof, and acrylic resin.

[0032] Examples of thermoplastic resins include liquid crystal polymers (LCP), fluororesins, thermoplastic polyimide resins, polyether ether ketone resins (PEEK), and polyphenylene sulfide resins (PPS).

[0033] The resin insulation layer is preferably made of a liquid crystal polymer (LCP), which has a lower water absorption rate than other thermoplastic resins. Therefore, when the resin insulation layer is made of a liquid crystal polymer, the amount of moisture remaining in the resin insulation layer can be reduced.

[0034] The resin insulating layer may contain an inorganic material such as a ceramic filler.

[0035] Examples of ceramic fillers include boron nitride, talc, and fused silica.

[0036] Examples of ceramics that form the ceramic insulating layer include low temperature co-fired ceramics (LTCC) and high temperature co-fired ceramics (HTCC).

[0037] The thickness of one insulating layer 10 is preferably 10 μm or more and 100 μm or less.

[0038] The first conductor layer 21 is provided on the first main surface 10 a of the insulating layer 10 and is connected to the first interlayer connection conductor 31 .

[0039] The second conductor layer 22 is provided on the second main surface 10 b of the insulating layer 10 and is connected to the first interlayer connection conductor 31 .

[0040] The first conductor layer 21 and the second conductor layer 22 may each have a patterned shape such as a wiring, or may have a planar shape that extends over a surface. The shapes of the first conductor layer 21 and the second conductor layer 22 may be the same as or different from each other.

[0041] The first conductor layer 21 and the second conductor layer 22 are each a metal layer containing, for example, copper, silver, aluminum, stainless steel, nickel, gold, or at least one of these metals. The materials of the first conductor layer 21 and the second conductor layer 22 may be the same or different. The first conductor layer 21 and the second conductor layer 22 are both preferably made of metal foil, more preferably copper (Cu) foil.

[0042] The first conductor layer 21 and the second conductor layer 22 may each have a matte surface on one main surface and a shiny surface on the other main surface.

[0043] The thickness (length in the stacking direction) of each of the first conductor layer 21 and the second conductor layer 22 is preferably 1 μm or more and 35 μm or less, and more preferably 6 μm or more and 18 μm or less. The thicknesses of the first conductor layer 21 and the second conductor layer 22 may be the same as or different from each other.

[0044] The first conductor layer 21 and the second conductor layer 22 may or may not be parallel to each other.

[0045] One insulating layer 10 may be provided between the first conductor layer 21 and the second conductor layer 22, or two or more insulating layers 10 may be provided. When two or more insulating layers 10 are provided between the first conductor layer 21 and the second conductor layer 22, the configurations of the insulating layers 10 may be the same as or different from each other. Furthermore, when two or more insulating layers 10 are provided between the first conductor layer 21 and the second conductor layer 22, the thicknesses of the insulating layers 10 may be the same as or different from each other.

[0046] The third conductor layer 23 is provided on the first main surface 10 a of the insulating layer 10 and is connected to the second interlayer connection conductor 32 .

[0047] The fourth conductor layer 24 is provided on the second main surface 10 b of the insulating layer 10 and is connected to the second interlayer connection conductor 32 .

[0048] The third conductor layer 23 and the fourth conductor layer 24 may each have a patterned shape such as a wiring, or may have a planar shape that spreads over a surface. The shapes of the third conductor layer 23 and the fourth conductor layer 24 may be the same as or different from each other.

[0049] The third conductor layer 23 and the fourth conductor layer 24 are each a metal layer containing, for example, copper, silver, aluminum, stainless steel, nickel, gold, or at least one of these metals. The materials of the third conductor layer 23 and the fourth conductor layer 24 may be the same or different. The third conductor layer 23 and the fourth conductor layer 24 are both preferably made of metal foil, more preferably copper (Cu) foil.

[0050] The third conductor layer 23 and the fourth conductor layer 24 may each have a matte surface on one main surface and a shiny surface on the other main surface.

[0051] The thickness (length in the stacking direction) of each of the third conductor layer 23 and the fourth conductor layer 24 is preferably 1 μm or more and 35 μm or less, and more preferably 6 μm or more and 18 μm or less. The thicknesses of the third conductor layer 23 and the fourth conductor layer 24 may be the same as or different from each other.

[0052] The third conductor layer 23 and the fourth conductor layer 24 may or may not be parallel to each other.

[0053] One insulating layer 10 may be provided between the third conductor layer 23 and the fourth conductor layer 24, or two or more insulating layers 10 may be provided. When two or more insulating layers 10 are provided between the third conductor layer 23 and the fourth conductor layer 24, the configurations of the insulating layers 10 may be the same as or different from each other. Furthermore, when two or more insulating layers 10 are provided between the third conductor layer 23 and the fourth conductor layer 24, the thicknesses of the insulating layers 10 may be the same as or different from each other.

[0054] The first interlayer connection conductor 31 and the second interlayer connection conductor 32 are provided to penetrate the insulating layer 10 in the thickness direction.

[0055] The first interlayer connection conductor 31 is provided so as to penetrate the insulating layer 10 in the thickness direction but not through the first conductor layer 21 or the second conductor layer 22, and to be connected to the first conductor layer 21 and the second conductor layer 22. Therefore, the first interlayer connection conductor 31 penetrates the insulating layer 10 in the thickness direction by the number of layers provided between the first conductor layer 21 and the second conductor layer 22. For example, the first interlayer connection conductor 31 is provided so as to penetrate one insulating layer 10 in the thickness direction.

[0056] The second interlayer connection conductor 32 is provided so as to penetrate the insulating layer 10 in the thickness direction but not through the third conductor layer 23 and the fourth conductor layer 24, and to be connected to the third conductor layer 23 and the fourth conductor layer 24. Therefore, the second interlayer connection conductor 32 penetrates the insulating layer 10 in the thickness direction by the number of layers provided between the third conductor layer 23 and the fourth conductor layer 24. For example, the second interlayer connection conductor 32 is provided so as to penetrate one insulating layer 10 in the thickness direction.

[0057] The insulating layer 10 on which the first interlayer connection conductor 31 is provided may be the same layer as or a different layer from the insulating layer 10 on which the second interlayer connection conductor 32 is provided, but is preferably a different layer. In this case, the thickness of the insulating layer 10 on which the first interlayer connection conductor 31 is provided is preferably smaller than the thickness of the insulating layer 10 on which the second interlayer connection conductor 32 is provided.

[0058] For example, when the circuit board 1A is a multilayer circuit board including a plurality of insulating layers 10, it is preferable that the insulating layer 10 on which the first interlayer connection conductor 31 is provided is a layer different in the thickness direction from the insulating layer 10 on which the second interlayer connection conductor 32 is provided. In this case, the insulating layer 10 on which the first interlayer connection conductor 31 is provided and the insulating layer 10 on which the second interlayer connection conductor 32 is provided may be adjacent in the thickness direction, or at least one insulating layer 10 may be disposed between the insulating layer 10 on which the first interlayer connection conductor 31 is provided and the insulating layer 10 on which the second interlayer connection conductor 32 is provided.

[0059] In a cross section perpendicular to the thickness direction, the first interlayer connection conductor 31 and the second interlayer connection conductor 32 preferably have a circular shape. In this case, the circle includes not only a perfect circle but also an ellipse, an oval, etc. The cross-sectional shapes of the first interlayer connection conductor 31 and the second interlayer connection conductor 32 may be the same or different from each other.

[0060] The first interlayer connection conductor 31 includes a first portion 31A and a second portion 31B in the thickness direction.

[0061] The first portion 31A is, for example, a plated via, where the plated via refers to a film grown by a liquid phase method or a vapor phase method.

[0062] When the first portion 31A is a plated via, the metal contained in the first portion 31A is preferably the same as the metal constituting the first conductor layer 21, for example, Cu.

[0063] The second portion 31B has a lower conductivity than the first portion 31A.

[0064] The second portion 31B is, for example, a paste via. Here, the paste via refers to a solidified paste. When the circuit board 1A is fabricated by batch pressing, which will be described later, the second portion 31B functions as a bonding material, thereby electrically connecting the first portion 31A and the second conductor layer 22.

[0065] When the second portion 31B is a paste via, examples of the metal contained in the second portion 31B include Cu, Sn, Ag, Ni, Cr, Pt, Mo, Ga, Ge, Sb, In, Pb, and alloys containing at least one of these metals. The metal contained in the second portion 31B may be the same as or different from the metal contained in the first portion 31A. The metal contained in the second portion 31B is, for example, an alloy containing Cu and Sn.

[0066] Alternatively, the second portion 31B may be a plated via.

[0067] When the second portion 31B is a plated via, the metal contained in the second portion 31B may be, for example, Sn. By using Sn, which has a low melting point, the second portion 31B can easily function as a bonding material.

[0068] One end of the first portion 31A is joined to the first conductor layer 21, and the other end of the first portion 31A is joined to one end of the second portion 31B.

[0069] The first portion 31A and the first conductor layer 21 are directly bonded without a dissimilar material therebetween, so that the interface between the first portion 31A and the first conductor layer 21 includes a portion where no dissimilar material exists, i.e., a portion where the first portion 31A and the first conductor layer 21 are in direct contact with each other.

[0070] The other end of the second portion 31B is joined to the second conductor layer 22 .

[0071] The second interlayer connection conductor 32 includes a third portion 32A and a fourth portion 32B in the thickness direction.

[0072] The third portion 32A is, for example, a plated via.

[0073] When the third portion 32A is a plated via, the metal contained in the third portion 32A is preferably the same as the metal constituting the third conductor layer 23, for example, Cu. The metal contained in the third portion 32A is preferably the same as the metal contained in the first portion 31A.

[0074] The fourth portion 32B has a lower conductivity than the third portion 32A.

[0075] The fourth portion 32B is, for example, a paste via. When the circuit board 1A is fabricated by batch pressing, which will be described later, the fourth portion 32B functions as a bonding material, thereby electrically connecting the third portion 32A and the fourth conductor layer 24.

[0076] When the fourth portion 32B is a paste via, examples of the metal contained in the fourth portion 32B include Cu, Sn, Ag, Ni, Cr, Pt, Mo, Ga, Ge, Sb, In, Pb, and alloys containing at least one of these metals. The metal contained in the fourth portion 32B may be the same as or different from the metal contained in the third portion 32A. The metal contained in the fourth portion 32B is, for example, an alloy containing Cu and Sn. It is preferable that the metal contained in the fourth portion 32B be the same as the metal contained in the second portion 31B.

[0077] Alternatively, the fourth portion 32B may be a plated via.

[0078] When the fourth portion 32B is a plated via, the metal contained in the fourth portion 32B may be, for example, Sn. Using Sn, which has a low melting point, makes it easier for the fourth portion 32B to function as a bonding material. The metal contained in the fourth portion 32B is preferably the same as the metal contained in the second portion 31B.

[0079] One end of the third portion 32A is joined to the third conductor layer 23, and the other end of the third portion 32A is joined to one end of the fourth portion 32B.

[0080] The third portion 32A and the third conductor layer 23 are directly bonded to each other without any dissimilar material therebetween, so that the interface between the third portion 32A and the third conductor layer 23 includes a portion where no dissimilar material exists, i.e., a portion where the third portion 32A and the third conductor layer 23 are in direct contact with each other.

[0081] The other end of the fourth portion 32B is joined to the fourth conductor layer 24 .

[0082] As shown in FIGS. 2A and 2B, the height of the first portion 31A is set to A １ , the height of the second portion 31B is B １ , the height of the third portion 32A is A ２ , the height of the fourth portion 32B is B ２ , the height of the first interlayer connection conductor 31 is T １ , the height of the second interlayer connection conductor 32 is T ２ When this is done, T １ <T ２ , and B１ / A １ >B ２ / A ２ The following relationship holds.

[0083] That is, of the first interlayer connection conductor 31 and the second interlayer connection conductor 32, the second interlayer connection conductor 32, which has a greater height, has a smaller proportion of low conductivity portions than the first interlayer connection conductor 31, which has a smaller height. This makes it possible to suppress an increase in the resistance value of the entire interlayer connection conductor, even when interlayer connection conductors of different heights are included.

[0084] On the other hand, of the first interlayer connection conductor 31 and the second interlayer connection conductor 32, the first interlayer connection conductor 31, which has a smaller height, has a smaller proportion of a portion with high conductivity than the second interlayer connection conductor 32, which has a larger height. For example, when the first portion 31A is a plated via and the second portion 31B is a paste via, an increase in manufacturing costs can be suppressed by not forming more first portion 31A than necessary.

[0085] Height B of second portion 31B １ is the height B of the fourth portion 32B ２ It is preferable that T １ <T ２ , and B １ / A １ >B ２ / A ２ As long as the relationship holds, the height B of the second portion 31B １ is the height B of the fourth portion 32B ２ The height B of the fourth portion 32B may be larger than ２ It may be smaller than

[0086] The diameter of the first interlayer connection conductor 31 is preferably smaller than the diameter of the second interlayer connection conductor 32. １ <T ２ , and B １ / A １ >B ２ / A ２ As long as the above relationship holds, the diameter of the first interlayer connection conductor 31 may be equal to or larger than the diameter of the second interlayer connection conductor 32 .

[0087] Height is T １ In this case, the height A of the first portion 31A of the first interlayer connection conductor 31 having a larger diameter may be １ is the height A of the first portion 31A of the first interlayer connection conductor 31 having a small diameter. １ It is preferable that it is smaller than

[0088] Similarly, the height is T ２ In this case, the height A of the third portion 32A of the second interlayer connection conductor 32 having a larger diameter may be ２ is the height A of the third portion 32A of the second interlayer connection conductor 32 having a smaller diameter. ２ It is preferable that it is smaller than

[0089] T １ <T ２ , and B １ / A １ >B ２ / A ２ As long as the relationship holds, the height A of the first portion 31A １ is the height B of the second portion 31B １ The height B of the second portion 31B may be equal to １ Lower than (A １ <B １ ) may be used, but the height B of the second portion 31B １ higher than (A １ >B １ In particular, when the first interlayer connection conductor 31 has a tapered shape, the height A of the first portion 31A is preferably １ The height B of the second portion 31B １ By making the height higher than 31A, the connection area between the first portion 31A and the second portion 31B becomes larger, and therefore the connection reliability of the first interlayer connection conductor 31 can be improved.

[0090] Similarly, T １ <T ２ , and B １ / A １ >B ２ / A ２ As long as the relationship holds, the height A of the third portion 32A ２is the height B of the fourth portion 32B ２ The height B of the fourth portion 32B may be equal to ２ Lower than (A ２ <B ２ ) may be used, but the height B ２ higher than (A ２ >B ２ In particular, when the second interlayer connection conductor 32 has a tapered shape, the height A of the third portion 32A is preferably ２ The height B of the fourth portion 32B ２ By making the height higher than 32A, the connection area between the third portion 32A and the fourth portion 32B becomes larger, and therefore the connection reliability of the second interlayer connection conductor 32 can be improved.

[0091] The shape of the first interlayer connection conductor 31 is not limited to that shown in FIG. 2A.

[0092] The second portion 31B may have a tapered shape in which the area of ​​the end face on the first conductor layer 21 side is smaller than the area of ​​the end face on the second conductor layer 22 side. By increasing the area of ​​the second portion 31B that is connected to the second conductor layer 22, the connection strength between the second portion 31B and the second conductor layer 22 can be increased.

[0093] When the second portion 31B has a tapered shape, the inclination angle of the tapered shape may vary stepwise, which can further increase the connection strength between the second portion 31B and the second conductor layer 22. The inclination angle of the tapered shape may vary in two steps, three steps, or four or more steps.

[0094] Furthermore, the first portion 31A may have a tapered shape in which the area of ​​the end face on the first conductor layer 21 side is smaller than the area of ​​the end face on the second conductor layer 22 side.

[0095] When the first portion 31A has a tapered shape, the inclination angle of the tapered shape may vary stepwise. In this case, the inclination angle of the tapered shape may vary in two steps, three steps, or four or more steps.

[0096] From the above, the first interlayer connection conductor 31 may have a tapered shape in which the area of ​​the end face on the first conductor layer 21 side is smaller than the area of ​​the end face on the second conductor layer 22 side, as shown in FIG. 2A.

[0097] Alternatively, the first interlayer connection conductor 31 may have a shape in which the area of ​​the end face on the first conductor layer 21 side is equal to the area of ​​the end face on the second conductor layer 22 side. In other words, the first interlayer connection conductor 31 does not have to have a tapered shape.

[0098] Specifically, the first portion 31A may have a shape in which the area of ​​the end face on the first conductor layer 21 side is equal to the area of ​​the end face on the second conductor layer 22 side, and the second portion 31B may have a shape in which the area of ​​the end face on the first conductor layer 21 side is equal to the area of ​​the end face on the second conductor layer 22 side.

[0099] 2A , when the first interlayer connection conductor 31 has a tapered shape, strain stress tends to concentrate at the necking portion of the first interlayer connection conductor 31 (particularly, at the necking portion between the first interlayer connection conductor 31 and the first conductor layer 21). In contrast, when the first interlayer connection conductor 31 does not have a tapered shape, strain stress does not concentrate at the necking portion of the first interlayer connection conductor 31. Therefore, the stress acting on the first interlayer connection conductor 31 is dispersed, improving connection reliability.

[0100] In the example shown in Figure 2A, the end face of the first portion 31A on the second conductor layer 22 side is flat, but as described below, it may protrude toward the second conductor layer 22 or may be recessed toward the first conductor layer 21.

[0101] The shape of the second interlayer connection conductor 32 is not limited to that shown in FIG. 2B.

[0102] The fourth portion 32B may have a tapered shape in which the area of ​​the end face on the third conductor layer 23 side is smaller than the area of ​​the end face on the fourth conductor layer 24 side. By increasing the area of ​​the fourth portion 32B that is connected to the fourth conductor layer 24, the connection strength between the fourth portion 32B and the fourth conductor layer 24 can be increased.

[0103] When the fourth portion 32B has a tapered shape, the inclination angle of the tapered shape may vary stepwise, which can further increase the connection strength between the fourth portion 32B and the fourth conductor layer 24. The inclination angle of the tapered shape may vary in two steps, three steps, or four or more steps.

[0104] Furthermore, the third portion 32A may have a tapered shape in which the area of ​​the end face on the third conductor layer 23 side is smaller than the area of ​​the end face on the fourth conductor layer 24 side.

[0105] When the third portion 32A has a tapered shape, the inclination angle of the tapered shape may vary stepwise. In this case, the inclination angle of the tapered shape may vary in two steps, three steps, or four or more steps.

[0106] As described above, the second interlayer connection conductor 32 may have a tapered shape in which the area of ​​the end face on the third conductor layer 23 side is smaller than the area of ​​the end face on the fourth conductor layer 24 side, as shown in FIG. 2B.

[0107] Alternatively, the second interlayer connection conductor 32 may have a shape in which the area of ​​the end face on the third conductor layer 23 side is equal to the area of ​​the end face on the fourth conductor layer 24 side. In other words, the second interlayer connection conductor 32 does not have to have a tapered shape.

[0108] Specifically, the third portion 32A may have a shape in which the area of ​​the end face on the third conductor layer 23 side is equal to the area of ​​the end face on the fourth conductor layer 24 side, and the fourth portion 32B may have a shape in which the area of ​​the end face on the third conductor layer 23 side is equal to the area of ​​the end face on the fourth conductor layer 24 side.

[0109] In the example shown in Figure 2B, the end face of the third portion 32A on the fourth conductor layer 24 side is flat, but like the first interlayer connecting conductor 31, it may protrude toward the fourth conductor layer 24 or may be recessed toward the third conductor layer 23.

[0110] 3A and 3B are schematic diagrams for explaining a method for measuring the height of the first interlayer connection conductor, the height of the first portion, and the height of the second portion.

[0111] As shown in FIG. 3A, the measurement target is a first interlayer connection conductor 31 (L １ The cross section is polished in slices at 5 μm intervals from the position indicated by . The cross section is polished in the depth direction while scraping at regular intervals with coarse abrasive paper, and when the following conditions (1) and (2) are confirmed, finish polishing is performed using fine abrasive paper. The cross section is found to have the largest distance between the interface where the conductor layer such as Cu foil and the first portion 31A such as the plated via meet, and the largest distance from the interface to the apex (highest point) of the first portion 31A. From the obtained cross section, the height T of the first interlayer connection conductor 31 is calculated. １ , height A of the first portion 31A １ and the height B of the second portion 31B １ Measure.

[0112] Height T of the second interlayer connection conductor 32 ２ , height A of the third portion 32A ２ and the height B of the fourth portion 32B ２ The cross section can also be determined and measured in the same manner.

[0113] The circuit board 1A is manufactured, for example, by the following method. The circuit board 1A may be manufactured in the form of a single chip (individual piece), or may be manufactured by producing an aggregate substrate and then separating the individual pieces. The aggregate substrate here refers to a substrate that includes multiple circuit boards 1A.

[0114] 4A to 4D are cross-sectional views schematically illustrating an example of a process for preparing a first substrate filled with a first material and a second material.

[0115] First, as shown in FIG. 4A, a first substrate 61 is prepared, in which a conductor layer 20 is formed on one main surface of an insulating layer 10 .

[0116] For example, a metal foil such as a Cu foil is laminated on one main surface of the insulating layer 10, and the metal foil is patterned by photolithography to form the conductor layer 20. The insulating layer 10 is, for example, a resin sheet whose main component is a thermoplastic resin such as a liquid crystal polymer.

[0117] 4B , a via hole 70 is formed in the first substrate 61 so as to penetrate the insulating layer 10 and expose a portion of the upper surface of the conductor layer 20. The via hole 70 preferably has a tapered shape in which the hole diameter decreases toward the conductor layer 20.

[0118] For example, a via hole 70 is formed in the insulating layer 10 using a laser or the like so that the upper surface of the conductor layer 20 is exposed.

[0119] 4C , the via hole 70 is filled with a first material 71. The first material 71 is filled partway into the via hole 70. There are no particular limitations on the height of the first material 71 as long as it does not exceed the thickness of the insulating layer 10.

[0120] For example, by plating such as electrolytic plating, the via hole 70 is filled with a plating metal such as Cu as a first material 71. The first material 71 forms the first portion 31A (see FIG. 7).

[0121] 4D , the via hole 70 filled with the first material 71 is filled with a second material 72. The space in the via hole 70 is filled with the first material 71 and the second material 72.

[0122] For example, after the via hole 70 is filled with the first material 71, a conductive paste containing a metal material such as Cu or Sn and a resin material is filled as the second material 72. The second material 72 is solidified by a heating press, which will be described later, to form the second portion 31B (see FIG. 7 ).

[0123] It is also possible to fill a plated metal such as Sn as the second material 72, but there is a risk that the underlying metal of the first material 71 may re-melt depending on the metal selected as the second material 72. Therefore, from the viewpoint of increasing the degree of freedom in selecting the first material 71 and the second material 72, it is preferable to fill the via hole 70 with a plated metal as the first material 71 and then fill it with a conductive paste as the second material 72.

[0124] 5A to 5D are cross-sectional views schematically illustrating an example of a process for preparing a second substrate filled with a first material and a second material. The method illustrated in FIGS. 5A to 5D is similar to the method illustrated in FIGS. 4A to 4D.

[0125] First, as shown in FIG. 5A, a second substrate 62 is prepared, in which a conductor layer 20 is formed on one main surface of an insulating layer 10 .

[0126] For example, a metal foil such as a Cu foil is laminated on one main surface of the insulating layer 10, and the metal foil is patterned by photolithography to form the conductor layer 20. The insulating layer 10 is, for example, a resin sheet whose main component is a thermoplastic resin such as a liquid crystal polymer.

[0127] 5B , a via hole 70 is formed in the second substrate 62, which penetrates the insulating layer 10 and exposes a portion of the upper surface of the conductor layer 20. The via hole 70 preferably has a tapered shape in which the hole diameter decreases toward the conductor layer 20.

[0128] For example, a via hole 70 is formed in the insulating layer 10 using a laser or the like so that the upper surface of the conductor layer 20 is exposed.

[0129] 5C , the via hole 70 is filled with a first material 71. The first material 71 is filled partway into the via hole 70. The height of the first material 71 is not particularly limited as long as it does not exceed the thickness of the insulating layer 10.

[0130] For example, by plating such as electrolytic plating, the via hole 70 is filled with a plating metal such as Cu as a first material 71. The first material 71 forms the third portion 32A (see FIG. 7).

[0131] 5D, the via hole 70 filled with the first material 71 is filled with a second material 72. The space in the via hole 70 is filled with the first material 71 and the second material 72.

[0132] For example, after the via hole 70 is filled with the first material 71, a conductive paste containing a metal material such as Cu or Sn and a resin material is filled as the second material 72. The second material 72 is solidified by a heat press described later, thereby forming the fourth portion 32B (see FIG. 7 ).

[0133] It is also possible to fill a plated metal such as Sn as the second material 72, but there is a risk that the underlying metal of the first material 71 may re-melt depending on the metal selected as the second material 72. Therefore, from the viewpoint of increasing the degree of freedom in selecting the first material 71 and the second material 72, it is preferable to fill the via hole 70 with a plated metal as the first material 71 and then fill it with a conductive paste as the second material 72.

[0134] FIG. 6 is a cross-sectional view schematically showing an example of a step of laminating the base materials.

[0135] As shown in Fig. 6, a plurality of substrates including a first substrate 61 and a second substrate 62 are laminated. Fig. 6 shows an example in which a substrate 60 that is not filled with a first material 71 and a second material 72, a first substrate 61 that is filled with the first material 71 and the second material 72, and a second substrate 62 that is filled with the first material 71 and the second material 72 are laminated, but there is no particular limitation as long as the first interlayer connection conductor 31 and the second interlayer connection conductor 32 shown in Fig. 7 are formed.

[0136] FIG. 7 is a cross-sectional view schematically showing an example of a collective pressing process.

[0137] 7, heat and pressure are applied to press the components together, thereby completing the circuit board 1A.

[0138] According to this manufacturing method, the circuit board 1A can be easily manufactured by batch pressing the insulating layer 10. Therefore, the number of manufacturing steps for the circuit board 1A can be reduced, and manufacturing costs can be kept low.

[0139] Although not shown in Figure 2A etc., an anticorrosion layer 40 (see Figure 8A) described later may be provided at least at the interface between the first conductor layer 21 and the insulating layer 10. Similarly, although not shown in Figure 2B etc., an anticorrosion layer 40 (see Figure 8B) described later may be provided at least at the interface between the third conductor layer 23 and the insulating layer 10. The same applies to the following embodiments.

[0140] The anticorrosive layer 40 is formed by applying an anticorrosive treatment to the surface of the metal foil using a metal such as Zn, Ni, Cr, Mo, or Pt.

[0141] When the circuit board 1A is manufactured by the above-mentioned batch pressing, by placing an anti-rust layer 40 at the interface between the first conductor layer 21 or the third conductor layer 23 and the insulating layer 10, oxidation of the metal foil such as Cu foil that constitutes the first conductor layer 21 or the third conductor layer 23 is prevented, thereby suppressing a decrease in adhesion between the first conductor layer 21 or the third conductor layer 23 and the insulating layer 10.

[0142] When the circuit board 1A is produced by batch pressing, the thermal load on the interface between the first conductor layer 21 or the third conductor layer 23 and the insulating layer 10 is greater than the thermal load on the interface between the second conductor layer 22 or the fourth conductor layer 24 and the insulating layer 10. Therefore, it is preferable that the anticorrosive layer 40 be disposed at least at the interface between the first conductor layer 21 or the third conductor layer 23 and the insulating layer 10.

[0143] When the anticorrosive layer 40 is disposed at the interface between the first conductor layer 21 and the insulating layer 10, the anticorrosive layer 40 may or may not be in contact with the first portion 31A. Similarly, when the anticorrosive layer 40 is disposed at the interface between the third conductor layer 23 and the insulating layer 10, the anticorrosive layer 40 may or may not be in contact with the third portion 32A.

[0144] It is preferable that the anticorrosive layer 40 is not disposed between the first portion 31A and the first conductor layer 21. Similarly, it is preferable that the anticorrosive layer 40 is not disposed between the third portion 32A and the third conductor layer 23.

[0145] It is preferable that the anticorrosive layer 40 is not disposed at the interface between the second conductor layer 22 and the insulating layer 10. Similarly, it is preferable that the anticorrosive layer 40 is not disposed at the interface between the fourth conductor layer 24 and the insulating layer 10.

[0146] It is preferable that the anticorrosive layer 40 is not disposed between the second portion 31B and the second conductor layer 22. Similarly, it is preferable that the anticorrosive layer 40 is not disposed between the fourth portion 32B and the fourth conductor layer 24.

[0147] Fig. 8A is a cross-sectional view schematically showing an example of a circuit board according to a second embodiment of the present invention, and Fig. 8B is a cross-sectional view schematically showing an example of the circuit board at a position different from that shown in Fig. 8A.

[0148] In the circuit board 1B shown in Fig. 8A, the surface roughness of the first conductor layer 21 in contact with the insulating layer 10 is greater than the surface roughness of the second conductor layer 22 in contact with the insulating layer 10. Furthermore, as shown in Fig. 8B, the surface roughness of the third conductor layer 23 in contact with the insulating layer 10 is greater than the surface roughness of the fourth conductor layer 24 in contact with the insulating layer 10.

[0149] 8A or 8B , by increasing the surface roughness of the first conductor layer 21 or the third conductor layer 23 at the portion in contact with the insulating layer 10, the adhesive area between the insulating layer 10 and the first conductor layer 21 or the third conductor layer 23 increases, thereby increasing the adhesive strength between them. Therefore, when electronic components or the like are mounted on the first conductor layer 21 or the third conductor layer 23, they are less likely to be peeled off.

[0150] In addition, if the surface roughness of the first conductor layer 21 in contact with the insulating layer 10 is greater than the surface roughness of the second conductor layer 22 in contact with the insulating layer 10, the surface roughness of the third conductor layer 23 in contact with the insulating layer 10 may be less than the surface roughness of the fourth conductor layer 24 in contact with the insulating layer 10, or may be equal to the surface roughness of the fourth conductor layer 24 in contact with the insulating layer 10.

[0151] Furthermore, if the surface roughness of the third conductor layer 23 in contact with the insulating layer 10 is greater than the surface roughness of the fourth conductor layer 24 in contact with the insulating layer 10, the surface roughness of the first conductor layer 21 in contact with the insulating layer 10 may be less than the surface roughness of the second conductor layer 22 in contact with the insulating layer 10, or may be equal to the surface roughness of the second conductor layer 22 in contact with the insulating layer 10.

[0152] In the example shown in Figure 8A, an anti-rust layer 40 is provided at the interface between the first conductor layer 21 and the insulating layer 10, but the anti-rust layer 40 does not have to be provided at the interface between the first conductor layer 21 and the insulating layer 10.

[0153] In the example shown in Figure 8B, an anti-rust layer 40 is provided at the interface between the third conductor layer 23 and the insulating layer 10, but the anti-rust layer 40 does not have to be provided at the interface between the third conductor layer 23 and the insulating layer 10.

[0154] FIG. 9 is a cross-sectional view schematically showing an example of a circuit board according to a third embodiment of the present invention.

[0155] In the circuit board 1C shown in Fig. 9, the end face of the first portion 31A on the second conductor layer 22 side protrudes toward the second conductor layer 22. In the example shown in Fig. 9, the end faces of the first portion 31A on the second conductor layer 22 side protrude symmetrically.

[0156] FIG. 10 is a cross-sectional view schematically showing another example of the circuit board according to the fourth embodiment of the present invention.

[0157] 10, similarly to Fig. 9, the end face of the first portion 31A on the second conductor layer 22 side protrudes toward the second conductor layer 22. On the other hand, in the example shown in Fig. 10, the end face of the first portion 31A on the second conductor layer 22 side protrudes asymmetrically.

[0158] As shown in Figure 9 or Figure 10, when the end face of the first part 31A on the second conductor layer 22 side protrudes toward the second conductor layer 22, the connection area between the first part 31A and the second part 31B becomes larger, and the connection strength between the first part 31A and the second part 31B can be increased.

[0159] Height A of the first portion 31A １ is the height B of the second portion 31B１ The height B of the second portion 31B may be equal to １ Lower than (A １ <B １ ) may be used, but the height B of the second portion 31B １ higher than (A １ >B １ ) is preferable. １ is the height of the highest part, and B is the height of the second part 31B １ is defined as the height of the lowest part.

[0160] 9 and 10, there is one peak, but there may be two or more peaks. When there are two or more peaks, the peaks may have the same size, height, shape, etc.

[0161] Although not shown, the end face of the third portion 32A of the second interlayer connection conductor 32 on the fourth conductor layer 24 side may also protrude toward the fourth conductor layer 24. In this case, the end face of the third portion 32A on the fourth conductor layer 24 side may protrude symmetrically or asymmetrically.

[0162] When the end face of the third portion 32A on the fourth conductor layer 24 side protrudes toward the fourth conductor layer 24, the height A of the third portion 32A is ２ is the height B of the fourth portion 32B ２ The height B of the fourth portion 32B may be equal to ２ Lower than (A ２ <B ２ ) may be used, but the height B ２ higher than (A ２ >B ２ ) is preferable. ２ is the height of the highest part, and B is the height of the fourth part 32B ２ is defined as the height of the lowest part.

[0163] FIG. 11 is a cross-sectional view schematically showing an example of a circuit board according to a fifth embodiment of the present invention.

[0164] In the circuit board 1E shown in Fig. 11 , the end face of the first portion 31A on the second conductor layer 22 side is recessed toward the first conductor layer 21. In the example shown in Fig. 11 , the end face of the first portion 31A on the second conductor layer 22 side is recessed symmetrically.

[0165] FIG. 12 is a cross-sectional view schematically showing another example of the circuit board according to the fifth embodiment of the present invention.

[0166] 12, similarly to Fig. 11, the end face of the first portion 31A on the second conductor layer 22 side is recessed toward the first conductor layer 21. On the other hand, in the example shown in Fig. 12, the end face of the first portion 31A on the second conductor layer 22 side is recessed asymmetrically.

[0167] As shown in Figure 11 or 12, when the end face of the first part 31A on the second conductor layer 22 side is recessed toward the first conductor layer 21, the connection area between the first part 31A and the second part 31B becomes larger, and the connection strength between the first part 31A and the second part 31B can be increased.

[0168] Height A of the first portion 31A １ is the height B of the second portion 31B １ The height B of the second portion 31B may be equal to １ Lower than (A １ <B １ ) may be used, but the height B of the second portion 31B １ higher than (A １ >B １ ) is preferable. １ is the height of the lowest part, and B is the height of the second part 31B １ is defined as the height of the highest part.

[0169] 11 and 12, the valley has one apex, but two or more apexes may exist. When two or more apexes exist, the size, depth, shape, etc. of the valleys may be the same or different.

[0170] The end face of the first portion 31A on the second conductor layer 22 side may include a portion that protrudes toward the second conductor layer 22 and a portion that is recessed toward the first conductor layer 21 .

[0171] Although not shown, the end face of the third portion 32A of the second interlayer connection conductor 32 on the fourth conductor layer 24 side may also be recessed toward the third conductor layer 23. In this case, the end face of the third portion 32A on the fourth conductor layer 24 side may be recessed symmetrically or asymmetrically.

[0172] When the end face of the third portion 32A on the fourth conductor layer 24 side is recessed toward the third conductor layer 23, the height A of the third portion 32A is ２ is the height B of the fourth portion 32B ２ The height B of the fourth portion 32B may be equal to ２ Lower than (A ２ <B ２ ) may be used, but the height B ２ higher than (A ２ >B ２ ) is preferable. ２ is the height of the lowest part, and the height B of the fourth part 32B ２ is defined as the height of the highest part.

[0173] The end face of the third portion 32A on the fourth conductor layer 24 side may include a portion that protrudes toward the fourth conductor layer 24 and a portion that is recessed toward the third conductor layer 23 .

[0174] FIG. 13 is a cross-sectional view schematically showing an example of a circuit board according to a sixth embodiment of the present invention.

[0175] In the circuit board 1G shown in FIG. 13, the end face of the first portion 31A on the first conductor layer 21 side protrudes further toward the first conductor layer 21 side than the interface between the first conductor layer 21 and the insulating layer 10 .

[0176] As shown in Figure 13, if the end face of the first portion 31A on the first conductor layer 21 side protrudes toward the first conductor layer 21 further than the interface between the first conductor layer 21 and the insulating layer 10, the connection area between the first portion 31A and the first conductor layer 21 becomes larger, and the connection strength between the first portion 31A and the first conductor layer 21 can be increased.

[0177] In the example shown in FIG. 13, the end face of the first portion 31A on the first conductor layer 21 side protrudes symmetrically, but may protrude asymmetrically.

[0178] 13, there is one peak, but there may be two or more peaks. When there are two or more peaks, the peaks may have the same size, height, shape, etc.

[0179] Although not shown, the end face of the third portion 32A of the second interlayer connection conductor 32 on the third conductor layer 23 side may also protrude toward the third conductor layer 23 beyond the interface between the third conductor layer 23 and the insulating layer 10. In this case, the end face of the third portion 32A on the third conductor layer 23 side may protrude symmetrically or asymmetrically.

[0180] Fig. 14A is a cross-sectional view schematically showing an example of a circuit board according to a seventh embodiment of the present invention, and Fig. 14B is a cross-sectional view schematically showing an example of the circuit board at a position different from that shown in Fig. 14A.

[0181] In the circuit board 1H shown in Figure 14A, the first portion 31A is joined to the second portion 31B via a first intermediate layer 51 containing the metal contained in the first portion 31A and the metal contained in the second portion 31B, and is joined to the first conductor layer 21 without via the first intermediate layer 51.

[0182] As an example, a first intermediate layer 51 containing Cu and Sn is formed on the end of the second portion 31B on the first portion 31A side. In this case, for example, the first intermediate layer 51 contains Cu. ３ Sn, Cu ５ The first intermediate layer 51 is made of a Cu—Sn alloy such as Sn, but the composition of the first intermediate layer 51 is different from the composition of the second portion 31B.

[0183] The second portion 31B is joined to the second conductor layer 22 via a second intermediate layer 52 containing the metal contained in the second portion 31B and the metal contained in the second conductor layer 22 .

[0184] As an example, a second intermediate layer 52 containing Cu and Sn is formed on the end of the second portion 31B on the side of the second conductor layer 22. In this case, for example, the second intermediate layer 52 contains Cu. ３ Sn, Cu ５ The second intermediate layer 52 is made of a Cu--Sn alloy such as Sn, but the composition of the second intermediate layer 52 is different from the composition of the second portion 31B.

[0185] The first intermediate layer 51 may or may not extend to the interface between the first portion 31A and the insulating layer 10. When the first intermediate layer 51 extends to the interface between the first portion 31A and the insulating layer 10, the first intermediate layer 51 may reach the interface between the first conductor layer 21 and the insulating layer 10. This can further increase the connection strength between the first portion 31A and the first conductor layer 21.

[0186] The second intermediate layer 52 may or may not extend to the interface between the second conductor layer 22 and the insulating layer 10 .

[0187] The first intermediate layer 51 may be one layer or two or more layers, and similarly, the second intermediate layer 52 may be one layer or two or more layers.

[0188] The first intermediate layer 51 and the second intermediate layer 52 can be confirmed, for example, by using a scanning electron microscope (SEM) to observe a cross section obtained by cutting the insulating layer 10 in a direction parallel to the thickness direction. The first intermediate layer 51 and the second intermediate layer 52 have compositions different from those of both the first portion 31A and the second portion 31B, and therefore appear in a color tone different from that of the first portion 31A and the second portion 31B in the SEM photograph.

[0189] Even if the types of metal elements contained are the same, the case where the content ratios of the respective metal elements are different is also considered to be "different in composition." For example, Cu ５ Sn, Cu ３ Sn, Cu ６ Sn ５ The compositions all contain Cu and Sn as metal species, but since the content ratios of the metal species are different, they can be said to be different compositions.

[0190] In the circuit board 1H shown in Figure 14B, the third portion 32A is joined to the fourth portion 32B via a third intermediate layer 53 containing the metal contained in the third portion 32A and the metal contained in the fourth portion 32B, and is joined to the third conductor layer 23 without via the third intermediate layer 53.

[0191] As an example, a third intermediate layer 53 containing Cu and Sn is formed on the end of the fourth portion 32B on the third portion 32A side.３ Sn, Cu ５ The third intermediate layer 53 is made of a Cu--Sn alloy such as Sn, but the composition of the third intermediate layer 53 is different from the composition of the fourth portion 32B.

[0192] The fourth portion 32B is joined to the fourth conductor layer 24 via a fourth intermediate layer 54 containing the metal contained in the fourth portion 32B and the metal contained in the fourth conductor layer 24 .

[0193] As an example, a fourth intermediate layer 54 containing Cu and Sn is formed on the end of the fourth portion 32B on the side of the fourth conductor layer 24. In this case, for example, the fourth intermediate layer 54 contains Cu. ３ Sn, Cu ５ The fourth intermediate layer 54 is made of a Cu-Sn alloy such as Sn, but the composition of the fourth intermediate layer 54 is different from the composition of the fourth portion 32B.

[0194] The third intermediate layer 53 may or may not extend to the interface between the third portion 32A and the insulating layer 10. When the third intermediate layer 53 extends to the interface between the third portion 32A and the insulating layer 10, the third intermediate layer 53 may reach the interface between the third conductor layer 23 and the insulating layer 10. This can further increase the connection strength between the third portion 32A and the third conductor layer 23.

[0195] The fourth intermediate layer 54 may or may not extend to the interface between the fourth conductor layer 24 and the insulating layer 10 .

[0196] The third intermediate layer 53 may be one layer or two or more layers, and similarly, the fourth intermediate layer 54 may be one layer or two or more layers.

[0197] FIG. 15 is a cross-sectional view schematically showing an example of a circuit board according to an eighth embodiment of the present invention.

[0198] In the circuit board 1I shown in FIG. 15, a portion of the end face of the first portion 31A on the second conductor layer 22 side has a portion that protrudes toward the second conductor layer 22.

[0199] As shown in Figure 15, if there is a protruding portion (hereinafter also referred to as a protruding portion) on a part of the end face of the first portion 31A on the second conductor layer 22 side, the connection area between the first portion 31A and the second portion 31B becomes larger, as in Figure 9 or Figure 10, and therefore the connection strength between the first portion 31A and the second portion 31B can be increased.

[0200] There may be one protrusion or two or more protrusions on a part of the end face of the first portion 31A on the side of the second conductor layer 22. When there are two or more protrusions, the size, height, shape, etc. of the protrusions may be the same or different.

[0201] The height of the protrusion is, for example, 1 μm or more and 20 μm or less. The shape of the protrusion is not limited to the shape shown in FIG.

[0202] The maximum diameter of the protrusion is, for example, 1 μm or more and 10 μm or less. Here, the maximum diameter of the protrusion refers to the diameter when the cross-sectional shape is circular, or the maximum length passing through the center of the cross-section when the cross-section shape is other than circular.

[0203] Although not shown, the second interlayer connecting conductor 32 may also have a portion on the end face of the third portion 32A on the fourth conductor layer 24 side that protrudes toward the fourth conductor layer 24.

[0204] FIG. 16 is a cross-sectional view schematically showing an example of a circuit board according to a ninth embodiment of the present invention.

[0205] In the circuit board 1J shown in FIG. 16, a portion recessed toward the first conductor layer 21 exists in part of the end face of the first portion 31A on the second conductor layer 22 side.

[0206] As shown in Figure 16, if there is a recessed portion (hereinafter also referred to as a recessed portion) on part of the end face of the first portion 31A on the second conductor layer 22 side, the connection area between the first portion 31A and the second portion 31B becomes larger, as in Figure 11 or Figure 12, and the connection strength between the first portion 31A and the second portion 31B can be increased.

[0207] There may be one recess or two or more recesses in a part of the end face of the first portion 31A on the side of the second conductor layer 22. When there are two or more recesses, the size, depth, shape, etc. of the recesses may be the same or different.

[0208] The depth of the recess is, for example, 1 μm or more and 20 μm or less. Note that the shape of the recess is not limited to the shape shown in FIG.

[0209] The maximum diameter of the recessed portion is, for example, 1 μm or more and 10 μm or less. Here, the maximum diameter of the recessed portion refers to the diameter when the cross-sectional shape is circular, and refers to the maximum length passing through the center of the cross-section when the cross-section shape is other than circular.

[0210] A part of the end surface of the first portion 31A on the second conductor layer 22 side may have a mixture of a protruding portion and a recessed portion.

[0211] Although not shown, the second interlayer connection conductor 32 may also have a portion of the end face of the third portion 32A on the fourth conductor layer 24 side that is recessed toward the third conductor layer 23.

[0212] A part of the end face of the third portion 32A on the fourth conductor layer 24 side may have a mixture of a protruding portion and a recessed portion.

[0213] FIG. 17 is a cross-sectional view schematically showing another example of a circuit board according to the ninth embodiment of the present invention.

[0214] As in the circuit board 1K shown in FIG. 17, a part of the second portion 31B may be joined to the first conductor layer 21.

[0215] Although not shown, the second interlayer connection conductor 32 may also have a part of the fourth portion 32B joined to the third conductor layer 23 in the same manner.

[0216] 18A, 18B, and 18C are cross-sectional views schematically showing examples of a circuit board according to a tenth embodiment of the present invention.

[0217] As in the circuit board 1L shown in FIG. 18A , the circuit board 1M shown in FIG. 18B , or the circuit board 1N shown in FIG. 18C , voids may exist within the first portion 31A. The number, size, location, etc. of the voids are not particularly limited. For example, the voids may exist near the interface between the first portion 31A and the first conductor layer 21 as shown in FIG. 18A , near the interface between the insulating layer 10 and the first conductor layer 21 as shown in FIG. 18B , or near the interface between the first portion 31A and the second portion 31B as shown in FIG. 18C . In addition to or instead of the voids, resin residues (carbides), copper foil oxides (copper oxide), etc. may also be present.

[0218] Although not shown, voids may also be present inside the third portion 32A of the second interlayer connection conductor 32. The number, size, position, etc. of the voids are not particularly limited. In addition to or instead of the voids, resin residues (carbides), copper foil oxides (copper oxide), etc. may also be present.

[0219] Fig. 19A is a cross-sectional view schematically showing an example of a circuit board according to an eleventh embodiment of the present invention, and Fig. 19B is a cross-sectional view schematically showing an example of the circuit board at a position different from that shown in Fig. 19A.

[0220] Although the overall configuration is not shown in Figures 19A and 19B, the circuit board 1O comprises an insulating layer 10, a first conductor layer 21, a second conductor layer 22, a fifth conductor layer 25, a sixth conductor layer 26, a first interlayer connection conductor 31, and a third interlayer connection conductor 33.

[0221] Although not shown, the circuit board 1O may or may not include a second interlayer connection conductor 32.

[0222] The fifth conductor layer 25 is provided on the first main surface 10 a of the insulating layer 10 and is connected to the third interlayer connection conductor 33 .

[0223] The sixth conductor layer 26 is provided on the second main surface 10 b of the insulating layer 10 and is connected to the third interlayer connection conductor 33 .

[0224] The fifth conductor layer 25 and the sixth conductor layer 26 may each have a patterned shape such as a wiring, or may have a planar shape that spreads over a surface. The shapes of the fifth conductor layer 25 and the sixth conductor layer 26 may be the same as or different from each other.

[0225] The fifth conductor layer 25 and the sixth conductor layer 26 are each a metal layer containing, for example, copper, silver, aluminum, stainless steel, nickel, or gold, or at least one of these metals. The materials of the fifth conductor layer 25 and the sixth conductor layer 26 may be the same or different. The fifth conductor layer 25 and the sixth conductor layer 26 are both preferably made of metal foil, more preferably copper (Cu) foil.

[0226] The fifth conductor layer 25 and the sixth conductor layer 26 may each have a matte surface on one main surface and a shiny surface on the other main surface.

[0227] The thickness (length in the stacking direction) of each of the fifth conductor layer 25 and the sixth conductor layer 26 is preferably 1 μm or more and 35 μm or less, and more preferably 6 μm or more and 18 μm or less. The thicknesses of the fifth conductor layer 25 and the sixth conductor layer 26 may be the same as or different from each other.

[0228] The fifth conductor layer 25 and the sixth conductor layer 26 may or may not be parallel to each other.

[0229] One insulating layer 10 may be provided between the fifth conductor layer 25 and the sixth conductor layer 26, or two or more insulating layers 10 may be provided. When two or more insulating layers 10 are provided between the fifth conductor layer 25 and the sixth conductor layer 26, the configurations of the insulating layers 10 may be the same as or different from each other. Furthermore, when two or more insulating layers 10 are provided between the fifth conductor layer 25 and the sixth conductor layer 26, the thicknesses of the insulating layers 10 may be the same as or different from each other.

[0230] The third interlayer connection conductor 33 is provided to penetrate the insulating layer 10 in the thickness direction.

[0231] The third interlayer connection conductor 33 is provided so as to penetrate the insulating layer 10 in the thickness direction but not through the fifth conductor layer 25 and the sixth conductor layer 26, and to be connected to the fifth conductor layer 25 and the sixth conductor layer 26. Therefore, the third interlayer connection conductor 33 penetrates the insulating layer 10 in the thickness direction by the number of layers provided between the fifth conductor layer 25 and the sixth conductor layer 26. For example, the third interlayer connection conductor 33 is provided so as to penetrate two insulating layers 10 in the thickness direction.

[0232] The insulating layer 10 on which the third interlayer connection conductor 33 is provided may be the same layer as or a different layer from the insulating layer 10 on which the first interlayer connection conductor 31 is provided, but is preferably a different layer. In this case, the thickness of the insulating layer 10 on which the third interlayer connection conductor 33 is provided may be greater than the thickness of the insulating layer 10 on which the first interlayer connection conductor 31 is provided, may be smaller than the thickness of the insulating layer 10 on which the first interlayer connection conductor 31 is provided, or may be equal to the thickness of the insulating layer 10 on which the first interlayer connection conductor 31 is provided.

[0233] For example, when the circuit board 1O is a multilayer circuit board including a plurality of insulating layers 10, it is preferable that the insulating layer 10 on which the third interlayer connection conductor 33 is provided is a layer different in the thickness direction from the insulating layer 10 on which the first interlayer connection conductor 31 is provided. In this case, the insulating layer 10 on which the third interlayer connection conductor 33 is provided and the insulating layer 10 on which the first interlayer connection conductor 31 is provided may be adjacent in the thickness direction, or at least one insulating layer 10 may be disposed between the insulating layer 10 on which the third interlayer connection conductor 33 is provided and the insulating layer 10 on which the first interlayer connection conductor 31 is provided.

[0234] In a cross section perpendicular to the thickness direction, the shape of the third interlayer connection conductor 33 is preferably circular. In this case, not only a perfect circle but also an ellipse, an oval, etc. are included in the circle. The cross-sectional shapes of the first interlayer connection conductor 31 and the third interlayer connection conductor 33 may be the same or different from each other.

[0235] The third interlayer connection conductor 33 includes a fifth portion 33A, a sixth portion 33B, and a seventh portion 33C in the thickness direction.

[0236] The fifth portion 33A is, for example, a plated via.

[0237] When the fifth portion 33A is a plated via, the metal contained in the fifth portion 33A is preferably the same as the metal constituting the fifth conductor layer 25, for example, Cu. The metal contained in the fifth portion 33A is preferably the same as the metal contained in the first portion 31A.

[0238] The sixth portion 33B has a lower conductivity than the fifth portion 33A.

[0239] The sixth portion 33B is, for example, a paste via. When the circuit board 1O is fabricated by the above-described batch pressing, the sixth portion 33B functions as a bonding material, thereby electrically connecting the fifth portion 33A and the sixth conductor layer 26.

[0240] When the sixth portion 33B is a paste via, examples of the metal contained in the sixth portion 33B include Cu, Sn, Ag, Ni, Cr, Pt, Mo, Ga, Ge, Sb, In, Pb, and alloys containing at least one of these metals. The metal contained in the sixth portion 33B may be the same as or different from the metal contained in the fifth portion 33A. The metal contained in the sixth portion 33B is, for example, an alloy containing Cu and Sn. The metal contained in the sixth portion 33B is preferably the same as the metal contained in the second portion 31B.

[0241] Alternatively, the sixth portion 33B may be a plated via.

[0242] When the sixth portion 33B is a plated via, the metal contained in the sixth portion 33B may be, for example, Sn. Using Sn, which has a low melting point, makes it easier for the sixth portion 33B to function as a bonding material. The metal contained in the sixth portion 33B is preferably the same as the metal contained in the second portion 31B.

[0243] The seventh portion 33C has a higher conductivity than the sixth portion 33B.

[0244] The seventh portion 33C is, for example, a plated via.

[0245] When the seventh portion 33C is a plated via, the metal contained in the seventh portion 33C is preferably the same as the metal constituting the sixth conductor layer 26, for example, Cu. The metal contained in the seventh portion 33C is preferably the same as the metal contained in the fifth portion 33A.

[0246] One end of the fifth portion 33A is joined to the fifth conductor layer 25, and the other end of the fifth portion 33A is joined to one end of the sixth portion 33B.

[0247] The fifth portion 33A and the fifth conductor layer 25 are directly bonded to each other without any dissimilar material therebetween, so that the interface between the fifth portion 33A and the fifth conductor layer 25 includes a portion where no dissimilar material exists, i.e., a portion where the fifth portion 33A and the fifth conductor layer 25 are in direct contact with each other.

[0248] The other end of the sixth portion 33B is joined to one end of the seventh portion 33C.

[0249] The other end of the seventh portion 33C is joined to the sixth conductor layer 26 .

[0250] The seventh portion 33C and the sixth conductor layer 26 are directly bonded to each other without any dissimilar material therebetween, so that the interface between the seventh portion 33C and the sixth conductor layer 26 includes a portion where no dissimilar material exists, i.e., a portion where the seventh portion 33C and the sixth conductor layer 26 are in direct contact with each other.

[0251] As shown in FIGS. 19A and 19B, the height of the first portion 31A is set to A １ , the height of the second portion 31B is B １ , the height of the fifth portion 33A is A ３ , the height of the sixth portion 33B is B ３ , the height of the seventh portion 33C is C ３ , the height of the first interlayer connection conductor 31 is T １ , the height of the third interlayer connection conductor 33 is T ３ When this is done, T １ <T ３ , and B １ / A １ >B ３ / (A ３ +C ３ ) relationship holds.

[0252] That is, of the first interlayer connection conductor 31 and the third interlayer connection conductor 33, the third interlayer connection conductor 33, which has a greater height, has a smaller proportion of low conductivity portions than the first interlayer connection conductor 31, which has a smaller height. This makes it possible to suppress an increase in the resistance value of the entire interlayer connection conductor, even when interlayer connection conductors of different heights are included.

[0253] On the other hand, of the first interlayer connection conductor 31 and the third interlayer connection conductor 33, the first interlayer connection conductor 31, which has a smaller height, has a smaller proportion of a portion with high conductivity than the third interlayer connection conductor 33, which has a larger height. For example, when the first portion 31A is a plated via and the second portion 31B is a paste via, an increase in manufacturing costs can be suppressed by not forming more first portion 31A than necessary.

[0254] Height B of second portion 31B １ is the height B of the sixth portion 33B ３ It is preferable that the value is equal to half of T １ <T ３ , and B １ / A １ >B ３ / (A ３ +C ３ ) is satisfied, the height B of the second portion 31B １ is the height B of the sixth portion 33B ３ The height B of the sixth portion 33B may be larger than half of the height B of the sixth portion 33B. ３ It may be smaller than half of

[0255] The diameter of the first interlayer connection conductor 31 is preferably smaller than the diameter of the third interlayer connection conductor 33. １ <T ３ , and B １ / A １ >B ３ / (A ３ +C ３ ) is satisfied, the diameter of the first interlayer connection conductor 31 may be equal to or larger than the diameter of the third interlayer connection conductor 33 .

[0256] Height A of the fifth portion 33A ３is the height C of the seventh portion 33C ３ However, the height C of the seventh portion 33C is preferably equal to ３ The height C of the seventh portion 33C may be larger than ３ It may be smaller than

[0257] Height is T ３ In this case, the height A of the fifth portion 33A of the third interlayer connection conductor 33 having a larger diameter may be ３ is the height A of the fifth portion 33A of the third interlayer connection conductor 33 having a smaller diameter. ３ Similarly, the height C of the seventh portion 33C of the third interlayer connection conductor 33 having a larger diameter is preferably smaller than ３ is the height C of the seventh portion 33C of the third interlayer connection conductor 33 having a smaller diameter. ３ It is preferable that it is smaller than

[0258] T １ <T ３ , and B １ / A １ >B ３ / (A ３ +C ３ ) holds true, the height A of the first portion 31A １ is the height B of the second portion 31B １ The height B of the second portion 31B may be equal to １ Lower than (A １ <B １ ) may be used, but the height B of the second portion 31B １ higher than (A １ >B １ In particular, when the first interlayer connection conductor 31 has a tapered shape, the height A of the first portion 31A is preferably １ The height B of the second portion 31B １ By making the height higher than 31A, the connection area between the first portion 31A and the second portion 31B becomes larger, and therefore the connection reliability of the first interlayer connection conductor 31 can be improved.

[0259] Similarly, T １ <T ３ , and B １ / A １ >B ３ / (A ３ +C ３ ) is satisfied, the height A of the fifth portion 33A ３ is the height B of the sixth portion 33B ３ The height B of the sixth portion 33B may be equal to half of the height B of the sixth portion 33B. ３ Lower than half of (A ３ <B ３ / 2), but the height B of the sixth portion 33B ３ Higher than half of (A ３ >B ３ In particular, when the fifth portion 33A has a tapered shape, the height A of the fifth portion 33A is preferably ３ The height B of the sixth portion 33B ３ By making the height higher than half of the height of the fifth portion 33A and the sixth portion 33B, the connection area between the fifth portion 33A and the sixth portion 33B becomes large, and therefore the connection reliability of the third interlayer connection conductor 33 can be improved.

[0260] Furthermore, T １ <T ３ , and B １ / A １ >B ３ / (A ３ +C ３ ) is satisfied, the height C of the seventh portion 33C ３ is the height B of the sixth portion 33B ３ The height B of the sixth portion 33B may be equal to half of the height B of the sixth portion 33B. ３ Lower than half of (C ３ <B ３ / 2), but the height B of the sixth portion 33B ３ Higher than half of (C ３ >B ３ In particular, when the seventh portion 33C has a tapered shape, the height C of the seventh portion 33C is preferably ３ The height B of the sixth portion 33B ３ By making the height higher than half of the height of the seventh portion 33C, the connection area between the seventh portion 33C and the sixth portion 33B increases, and therefore the connection reliability of the third interlayer connection conductor 33 can be improved.

[0261] The shape of the third interlayer connection conductor 33 is not limited to that shown in FIG. 19B.

[0262] In the example shown in Figure 19B, the third interlayer connection conductor 33 has a shape in which a set of second interlayer connection conductors 32 (see Figure 2B) having a tapered shape are connected in an inverted state, but the third interlayer connection conductor 33 does not have to have a tapered shape.

[0263] Although not shown in Fig. 19B, an anticorrosive layer 40 (see Fig. 8B) may be provided at least at the interface between the fifth conductor layer 25 and the insulating layer 10. Similarly, an anticorrosive layer 40 may be provided at least at the interface between the sixth conductor layer 26 and the insulating layer 10.

[0264] When the anticorrosive layer 40 is disposed at the interface between the fifth conductor layer 25 and the insulating layer 10, the anticorrosive layer 40 may or may not be in contact with the fifth portion 33A. Similarly, when the anticorrosive layer 40 is disposed at the interface between the sixth conductor layer 26 and the insulating layer 10, the anticorrosive layer 40 may or may not be in contact with the seventh portion 33C.

[0265] It is preferable that the anticorrosive layer 40 is not disposed between the fifth portion 33A and the fifth conductor layer 25. Similarly, it is preferable that the anticorrosive layer 40 is not disposed between the seventh portion 33C and the sixth conductor layer 26.

[0266] The surface roughness of the first conductor layer 21 in contact with the insulating layer 10 may be greater than the surface roughness of the second conductor layer 22 in contact with the insulating layer 10. In this case, the surface roughness of the fifth conductor layer 25 in contact with the insulating layer 10 may be equal to the surface roughness of the sixth conductor layer 26 in contact with the insulating layer 10, or may be greater than the surface roughness of the sixth conductor layer 26 in contact with the insulating layer 10, or may be smaller than the surface roughness of the sixth conductor layer 26 in contact with the insulating layer 10.

[0267] The end face of the fifth portion 33A on the sixth conductor layer 26 side may be flat, may protrude toward the sixth conductor layer 26, or may be recessed toward the fifth conductor layer 25.

[0268] The end face of the seventh portion 33C on the fifth conductor layer 25 side may be flat, may protrude toward the fifth conductor layer 25, or may be recessed toward the sixth conductor layer 26.

[0269] The end face of the fifth portion 33A on the fifth conductor layer 25 side may protrude further toward the fifth conductor layer 25 side than the interface between the fifth conductor layer 25 and the insulating layer 10 .

[0270] The end face of the seventh portion 33C on the sixth conductor layer 26 side may protrude further toward the sixth conductor layer 26 side than the interface between the sixth conductor layer 26 and the insulating layer 10 .

[0271] The fifth portion 33A may be joined to the sixth portion 33B via a fifth intermediate layer (not shown) containing the metal contained in the fifth portion 33A and the metal contained in the sixth portion 33B, and may also be joined to the fifth conductor layer 25 without the fifth intermediate layer.

[0272] For example, the sixth portion 33B may have a fifth intermediate layer containing Cu and Sn formed at the end portion on the fifth portion 33A side. ３ Sn, Cu ５ The fifth intermediate layer is made of a Cu--Sn alloy such as Sn, but the composition of the fifth intermediate layer is different from the composition of the sixth portion 33B.

[0273] The seventh portion 33C may be joined to the sixth portion 33B via a sixth intermediate layer (not shown) containing the metal contained in the seventh portion 33C and the metal contained in the sixth portion 33B, and may also be joined to the sixth conductor layer 26 without the sixth intermediate layer.

[0274] For example, a sixth intermediate layer containing Cu and Sn may be formed on the end of the sixth portion 33B on the seventh portion 33C side. In this case, for example, the sixth intermediate layer may contain Cu ３ Sn, Cu ５ The sixth intermediate layer is made of a Cu--Sn alloy such as Sn, but the composition of the sixth intermediate layer is different from the composition of the sixth portion 33B.

[0275] The fifth intermediate layer may or may not extend to the interface between the fifth portion 33A and the insulating layer 10. When the fifth intermediate layer extends to the interface between the fifth portion 33A and the insulating layer 10, the fifth intermediate layer may reach the interface between the fifth conductor layer 25 and the insulating layer 10.

[0276] The sixth intermediate layer may or may not extend to the interface between the seventh portion 33C and the insulating layer 10. When the sixth intermediate layer extends to the interface between the seventh portion 33C and the insulating layer 10, the sixth intermediate layer may reach the interface between the sixth conductor layer 26 and the insulating layer 10.

[0277] The fifth intermediate layer may be one layer or two or more layers, and similarly, the sixth intermediate layer may be one layer or two or more layers.

[0278] A portion of the end face of the fifth portion 33A on the sixth conductor layer 26 side may have a portion that protrudes toward the sixth conductor layer 26, a portion that is recessed toward the fifth conductor layer 25, or a mixture of these portions.

[0279] A part of the end face of the seventh portion 33C on the fifth conductor layer 25 side may have a part that protrudes toward the fifth conductor layer 25, a part that is recessed toward the sixth conductor layer 26, or a mixture of these parts.

[0280] A part of the sixth portion 33B may be joined to the fifth conductor layer 25 or may be joined to the sixth conductor layer 26 .

[0281] Voids may be present inside the fifth portion 33A. Similarly, voids may be present inside the seventh portion 33C. The number, size, position, etc. of the voids are not particularly limited. In addition to or instead of the voids, resin residues (carbides), copper foil oxides (copper oxide), etc. may be present.

[0282] The circuit board of the present invention is not limited to the above-described embodiment, and various applications and modifications can be made within the scope of the present invention with respect to the configuration of the circuit board, manufacturing conditions, and the like.

[0283] The circuit board of the present invention can be used, for example, as a substrate for a circuit module.

[0284] FIG. 20 is a cross-sectional view schematically showing an example of a circuit module including a circuit board according to the present invention.

[0285] The circuit module 100 shown in FIG. 20 includes a circuit board 110 and an electronic component 120 disposed on the circuit board 110 .

[0286] The circuit board 110 is the circuit board of the present invention. The circuit board 110 may be a rigid board or a flexible board. The circuit board 110 may have a bent portion.

[0287] The circuit board 110 includes an insulating layer 10 , a conductor layer 20 , and an interlayer connection conductor 30 .

[0288] The electronic component 120 is not particularly limited and may be, for example, an integrated circuit (IC), a connector, etc. One or more electronic components 120 may be arranged on either one of the main surfaces of the circuit board 110, or one or more electronic components 120 may be arranged on each of the main surfaces of the circuit board 110.

[0289] A protective layer 130 may be provided on the surface layer of the circuit board 110. The protective layer 130 may be, for example, a coverlay, a resist layer, or the like. The protective layer 130 may be provided on both main surfaces of the circuit board 110, or on one of the main surfaces.

[0290] In the circuit board 110, the interlayer connection conductor 30 includes the first interlayer connection conductor and the second interlayer connection conductor described in the above embodiment. The interlayer connection conductor 30 may include a third interlayer connection conductor in addition to the first interlayer connection conductor and the second interlayer connection conductor. Alternatively, the interlayer connection conductor 30 may include the third interlayer connection conductor instead of the second interlayer connection conductor.

[0291] The circuit board 110 may include interlayer connection conductors 30 other than the first interlayer connection conductor, the second interlayer connection conductor, and the third interlayer connection conductor.

[0292] For example, the interlayer connection conductors 30 may include interlayer connection conductors consisting only of plated vias, or may include interlayer connection conductors consisting only of paste vias, or may be a mixture of these.

[0293] As an example, the first interlayer connection conductor described in the above embodiment may be provided as the interlayer connection conductor 30 inside the insulating layer 10 located on the surface layer of the circuit board 110 on the side where the electronic component 120 is arranged (the lower side in FIG. 20 ). This makes it possible to ensure the connectivity of the interlayer connection conductor even in the fine wiring portion located on the surface layer.

[0294] Fig. 21 is a plan view schematically showing an example of a surface layer of a circuit board. Fig. 22A, Fig. 22B, and Fig. 22C are cross-sectional views schematically showing examples of interlayer connection conductors having a constant height but different diameters.

[0295] 21 , interlayer connection conductors a1, a2, b1, b2, c1, and c2 having a constant height but different diameters are provided on the surface layer of the circuit board. When these interlayer connection conductors are first interlayer connection conductors, it is preferable that the height of the first portion 31A of the first interlayer connection conductor 31 having a larger diameter be smaller than the height of the first portion 31A of the first interlayer connection conductor 31 having a smaller diameter, as shown in FIGS.

[0296] 21, it is expected that the pitch and diameter of the interlayer connection conductor a1 connected to the integrated circuit (IC) will become narrower. Therefore, it is preferable that the interlayer connection conductor a1 is the first interlayer connection conductor 31 shown in FIG. 22A.

[0297] 21, the interlayer connection conductor a2 connected to a signal line such as RF (Radio Frequency), IF (Intermediate Frequency), etc. is desired to have a small diameter for miniaturization. Therefore, the interlayer connection conductor a2 is preferably the first interlayer connection conductor 31 shown in FIG. 22A.

[0298] 21, the interlayer connection conductor b1 provided around the signal line is required to have a relatively small diameter to prevent electric field leakage of high frequency waves, etc. Therefore, the interlayer connection conductor b1 is preferably the first interlayer connection conductor 31 shown in FIG.

[0299] 21, the interlayer connection conductor b2 connected to the connector has a relatively large terminal land, so the diameter of the interlayer connection conductor b2 may also be large. Therefore, it is preferable that the interlayer connection conductor b2 is the first interlayer connection conductor 31 shown in FIG. 22B.

[0300] 21, the interlayer connection conductor c1 connected to the ground wiring is connected to a wide land, so the diameter of the interlayer connection conductor c1 may be large. Therefore, it is preferable that the interlayer connection conductor c1 is the first interlayer connection conductor 31 shown in FIG. 22C.

[0301] 21, a considerable amount of current flows through the interlayer connection conductor c2 connected to the power supply line, so it is necessary to increase the diameter of the interlayer connection conductor c2 to reduce its resistance. For this reason, it is preferable that the interlayer connection conductor c2 be the first interlayer connection conductor 31 shown in FIG. 22C.

[0302] The present specification discloses the following:

[0303] <1> An insulating layer having a first main surface and a second main surface opposed to each other in a thickness direction; first interlayer connection conductors and second interlayer connection conductors provided to penetrate the same or different insulating layers in the thickness direction; a first conductor layer provided on the first main surface of the insulating layer and connected to the first interlayer connection conductor; a second conductor layer provided on the second main surface of the insulating layer and connected to the first interlayer connection conductor; a third conductor layer provided on the first main surface of the insulating layer and connected to the second interlayer connection conductor; and a fourth conductor layer provided on the second main surface of the insulating layer and connected to the second interlayer connection conductor, wherein the first interlayer connection conductor includes a first portion and a second portion having a lower conductivity than the first portion in the thickness direction, one end of the first portion is joined to the first conductor layer, and the other end of the first portion is joined to one end of the second portion, the other end of the second portion is joined to the second conductor layer, the second interlayer connection conductor includes a third portion and a fourth portion having a lower conductivity than the third portion in the thickness direction, one end of the third portion is joined to the third conductor layer and the other end of the third portion is joined to one end of the fourth portion, the other end of the fourth portion is joined to the fourth conductor layer, and the height of the first portion is set to A １ , the height of the second portion is B １ , the height of the third portion is A ２ , the height of the fourth portion is B ２ , the height of the first interlayer connection conductor is T １ , the height of the second interlayer connection conductor is T ２ When this is done, T １ <T ２ , and B １ / A １ >B ２ / A ２ A circuit board where the above relationship holds.

[0304] <2> Height B of the second portion １ is the height B of the fourth portion ２ The circuit board according to <1>, which is equivalent to

[0305] <3> The circuit board according to <1> or <2>, wherein the diameter of the first interlayer connection conductor is smaller than the diameter of the second interlayer connection conductor.

[0306] <4> Height is T １ two or more types of the first interlayer connection conductors having different diameters are present, and the height A of the first portion of the first interlayer connection conductor having a larger diameter is １ is the height A of the first portion of the first interlayer connection conductor having a small diameter. １ <1> <2> The circuit board according to any one of <1> to <2>, wherein the thickness of the circuit board is smaller than the thickness of the circuit board.

[0307] <5> The circuit board according to any one of <1> to <4>, wherein the thickness of the insulating layer on which the first interlayer connection conductor is provided is smaller than the thickness of the insulating layer on which the second interlayer connection conductor is provided.

[0308] <6> The circuit board according to any one of <1> to <5>, wherein the surface roughness of the first conductor layer in contact with the insulating layer is greater than the surface roughness of the second conductor layer in contact with the insulating layer, and the surface roughness of the third conductor layer in contact with the insulating layer is greater than the surface roughness of the fourth conductor layer in contact with the insulating layer.

[0309] <7> The circuit board according to any one of <1> to <6>, wherein the second portion has a tapered shape in which an end face on the first conductor layer side has an area smaller than an end face on the second conductor layer side, and the fourth portion has a tapered shape in which an end face on the third conductor layer side has an area smaller than an end face on the fourth conductor layer side.

[0310] <8> The circuit board according to any one of <1> to <7>, wherein an end face of the first portion on the second conductor layer side protrudes toward the second conductor layer or is recessed toward the first conductor layer, and an end face of the third portion on the fourth conductor layer side protrudes toward the fourth conductor layer or is recessed toward the third conductor layer.

[0311] <9> The circuit board according to any one of <1> to <8>, wherein an end face of the first portion on the first conductor layer side protrudes toward the first conductor layer side beyond the interface between the first conductor layer and the insulating layer, and an end face of the third portion on the third conductor layer side protrudes toward the third conductor layer side beyond the interface between the third conductor layer and the insulating layer.

[0312] <10> The circuit board according to any one of <1> to <9>, wherein the first portion is bonded to the second portion via a first intermediate layer containing a metal contained in the first portion and a metal contained in the second portion, and is bonded to the first conductor layer without the first intermediate layer; the second portion is bonded to the second conductor layer via a second intermediate layer containing a metal contained in the second portion and a metal contained in the second conductor layer; the third portion is bonded to the fourth portion via a third intermediate layer containing a metal contained in the third portion and a metal contained in the fourth portion, and is bonded to the third conductor layer without the third intermediate layer; and the fourth portion is bonded to the fourth conductor layer via a fourth intermediate layer containing a metal contained in the fourth portion and a metal contained in the fourth conductor layer.

[0313] <11> The semiconductor device further comprises: a third interlayer connection conductor provided so as to penetrate, in the thickness direction, the insulating layer which is the same as or different from the insulating layer in which the first interlayer connection conductor is provided; a fifth conductor layer provided on the first main surface of the insulating layer and connected to the third interlayer connection conductor; and a sixth conductor layer provided on the second main surface of the insulating layer and connected to the third interlayer connection conductor, wherein the third interlayer connection conductor includes, in the thickness direction, a fifth portion, a sixth portion having a lower conductivity than the fifth portion, and a seventh portion having a higher conductivity than the sixth portion, one end of the fifth portion is joined to the fifth conductor layer, and the other end of the fifth portion is joined to one end of the sixth portion, the other end of the sixth portion is joined to one end of the seventh portion, and the other end of the seventh portion is joined to the sixth conductor layer, ３ , the height of the sixth portion is B ３ , the height of the seventh part is C ３, the height of the third interlayer connection conductor is T ３ When this is done, T １ <T ３ , and B １ / A １ >B ３ / (A ３ +C ３ <11> The circuit board according to any one of <1> to <10>, wherein the following relationship holds:

[0314] <12> An insulating layer having a first main surface and a second main surface opposed to each other in a thickness direction; a first interlayer connection conductor and a third interlayer connection conductor provided to penetrate the same or different insulating layers in the thickness direction; a first conductor layer provided on the first main surface of the insulating layer and connected to the first interlayer connection conductor; a second conductor layer provided on the second main surface of the insulating layer and connected to the first interlayer connection conductor; a fifth conductor layer provided on the first main surface of the insulating layer and connected to the third interlayer connection conductor; and a sixth conductor layer provided on the second main surface of the insulating layer and connected to the fourth interlayer connection conductor, wherein the first interlayer connection conductor includes a first portion and a second portion having a lower conductivity than the first portion in the thickness direction, one end of the first portion is joined to the first conductor layer, and the other end of the first portion is joined to one end of the second portion, the other end of the second portion is joined to the second conductor layer; the third interlayer connection conductor includes a fifth portion, a sixth portion having a lower conductivity than the fifth portion, and a seventh portion having a higher conductivity than the sixth portion in the thickness direction; one end of the fifth portion is joined to the fifth conductor layer and the other end of the fifth portion is joined to one end of the sixth portion; the other end of the sixth portion is joined to one end of the seventh portion; the other end of the seventh portion is joined to the sixth conductor layer; １ , the height of the second portion is B １ , the height of the fifth portion is A ３ , the height of the sixth portion is B ３ , the height of the seventh part is C ３ , the height of the first interlayer connection conductor is T １ , the height of the third interlayer connection conductor is T ３When this is done, T １ <T ３ , and B １ / A １ >B ３ / (A ３ +C ３ ) relationship holds true for a circuit board.

[0315] <13> Height B of the second portion １ is the height B of the sixth portion ３ The circuit board according to <11> or <12>, wherein the thickness is equal to half of the thickness of the circuit board.

[0316] <14> Height A of the fifth portion ３ is the height C of the seventh portion ３ <11> to <13>, wherein the circuit board is equivalent to the above.

[0317] <15> The circuit board according to any one of <11> to <14>, wherein the diameter of the first interlayer connection conductor is smaller than the diameter of the third interlayer connection conductor.

[0318] <16> The circuit board according to any one of <1> to <15>, wherein the insulating layer contains a thermoplastic resin as a main component.

[0319] 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, 1J, 1K, 1L, 1M, 1N, 1O Circuit board 10 Insulating layer 10a First main surface 10b Second main surface 20 Conductor layer 21 First conductor layer 22 Second conductor layer 23 Third conductor layer 24 Fourth conductor layer 25 Fifth conductor layer 26 Sixth conductor layer 30 Interlayer connection conductor 31 First interlayer connection conductor 31A First portion 31B Second portion 32 Second interlayer connection conductor 32A Third portion 32B Fourth portion 33 Third interlayer connection conductor 33A Fifth portion 33B Sixth portion 33C Seventh portion 40 Anti-corrosion layer 51 First intermediate layer 52 Second intermediate layer 53 Third intermediate layer 54 Fourth intermediate layer 60: Substrate 61: First substrate 62: Second substrate 70: Via hole 71: First material 72: Second material 100: Circuit module 110: Circuit board 120: Electronic component 130: Protective layer A １ Height of first part B１ Height of second part A ２ Height of the third part B ２ Height of the fourth section A ３ Height of the fifth part B ３ Height of the sixth part C ３ Height of the 7th part T １ Height of the first interlayer connection conductor T ２ Height of second interlayer connection conductor T ３ Height of third interlayer connection conductor: a1, a2, b1, b2, c1, c2

Claims

1. an insulating layer having a first main surface and a second main surface opposed to each other in a thickness direction; a first interlayer connection conductor and a second interlayer connection conductor provided to penetrate the same or different insulating layers in the thickness direction; a first conductor layer provided on the first main surface of the insulating layer and connected to the first interlayer connection conductor; a second conductor layer provided on the second main surface of the insulating layer and connected to the first interlayer connection conductor; a third conductor layer provided on the first main surface of the insulating layer and connected to the second interlayer connection conductor; a fourth conductor layer provided on the second main surface of the insulating layer and connected to the second interlayer connection conductor, the first interlayer connection conductor includes a first portion and a second portion having a lower conductivity than the first portion in the thickness direction; one end of the first portion is joined to the first conductor layer, and the other end of the first portion is joined to one end of the second portion; the other end of the second portion is joined to the second conductor layer; the second interlayer connection conductor includes a third portion and a fourth portion having a lower conductivity than the third portion in the thickness direction; one end of the third portion is joined to the third conductor layer, and the other end of the third portion is joined to one end of the fourth portion; the other end of the fourth portion is joined to the fourth conductor layer; The height of the first portion is A １ , the height of the second portion is B １ , the height of the third portion is A ２ , the height of the fourth portion is B ２ , the height of the first interlayer connection conductor is T １ , the height of the second interlayer connection conductor is T ２ When T １ <T ２ , and B １ / A １ >B ２ / A ２ A circuit board where the above relationship holds.

2. The height B of the second portion １ is the height B of the fourth portion ２ The circuit board of claim 1 , wherein the circuit board is equivalent to

3. 3. The circuit board according to claim 1, wherein the diameter of the first interlayer connection conductor is smaller than the diameter of the second interlayer connection conductor.

4. Height is T １ two or more types of the first interlayer connection conductors having different diameters are present, The height A of the first portion of the first interlayer connecting conductor having a large diameter １ is the height A of the first portion of the first interlayer connection conductor having a small diameter. １ The circuit board according to claim 1 or 2, wherein the circuit board is smaller than

5. 3. The circuit board according to claim 1, wherein the thickness of the insulating layer on which the first interlayer connection conductor is provided is smaller than the thickness of the insulating layer on which the second interlayer connection conductor is provided.

6. a surface roughness of the first conductor layer at a portion in contact with the insulating layer is greater than a surface roughness of the second conductor layer at a portion in contact with the insulating layer; 3. The circuit board according to claim 1, wherein a surface roughness of the third conductor layer in contact with the insulating layer is greater than a surface roughness of the fourth conductor layer in contact with the insulating layer.

7. the second portion has a tapered shape in which an area of ​​an end face on the first conductor layer side is smaller than an area of ​​an end face on the second conductor layer side, The circuit board according to claim 1 , wherein the fourth portion has a tapered shape in which an area of ​​an end face on the third conductor layer side is smaller than an area of ​​an end face on the fourth conductor layer side.

8. an end face of the first portion on the second conductor layer side protrudes toward the second conductor layer or is recessed toward the first conductor layer; 3. The circuit board according to claim 1, wherein an end face of the third portion on the side of the fourth conductor layer protrudes toward the fourth conductor layer or is recessed toward the third conductor layer.

9. an end face of the first portion on the first conductor layer side protrudes toward the first conductor layer beyond an interface between the first conductor layer and the insulating layer; 3. The circuit board according to claim 1, wherein an end face of the third portion on the third conductor layer side protrudes toward the third conductor layer beyond an interface between the third conductor layer and the insulating layer.

10. the first portion is bonded to the second portion via a first intermediate layer including a metal contained in the first portion and a metal contained in the second portion, and is bonded to the first conductor layer without the first intermediate layer; the second portion is bonded to the second conductor layer via a second intermediate layer containing a metal contained in the second portion and a metal contained in the second conductor layer; the third portion is bonded to the fourth portion via a third intermediate layer including a metal contained in the third portion and a metal contained in the fourth portion, and is bonded to the third conductor layer without the third intermediate layer; 3. The circuit board according to claim 1, wherein the fourth portion is joined to the fourth conductor layer via a fourth intermediate layer containing a metal contained in the fourth portion and a metal contained in the fourth conductor layer.

11. a third interlayer connection conductor provided to penetrate the insulating layer in the thickness direction, the insulating layer being the same as or different from the insulating layer in which the first interlayer connection conductor is provided; a fifth conductor layer provided on the first main surface of the insulating layer and connected to the third interlayer connection conductor; a sixth conductor layer provided on the second main surface of the insulating layer and connected to the third interlayer connection conductor, the third interlayer connection conductor includes, in the thickness direction, a fifth portion, a sixth portion having a lower conductivity than the fifth portion, and a seventh portion having a higher conductivity than the sixth portion; one end of the fifth portion is joined to the fifth conductor layer, and the other end of the fifth portion is joined to one end of the sixth portion; the other end of the sixth portion is joined to one end of the seventh portion; the other end of the seventh portion is joined to the sixth conductor layer; The height of the fifth portion is A ３ , the height of the sixth portion is B ３ , the height of the seventh portion is C ３ , the height of the third interlayer connection conductor is T ３ When T １ <T ３ , and B １ / A １ >B ３ / (A ３ +C ３ 2. The circuit board according to claim 1, wherein the following relationship holds:

12. an insulating layer having a first main surface and a second main surface opposed to each other in a thickness direction; a first interlayer connection conductor and a third interlayer connection conductor provided to penetrate the same or different insulating layers in the thickness direction; a first conductor layer provided on the first main surface of the insulating layer and connected to the first interlayer connection conductor; a second conductor layer provided on the second main surface of the insulating layer and connected to the first interlayer connection conductor; a fifth conductor layer provided on the first main surface of the insulating layer and connected to the third interlayer connection conductor; a sixth conductor layer provided on the second main surface of the insulating layer and connected to the fourth interlayer connection conductor, the first interlayer connection conductor includes a first portion and a second portion having a lower conductivity than the first portion in the thickness direction; one end of the first portion is joined to the first conductor layer, and the other end of the first portion is joined to one end of the second portion; the other end of the second portion is joined to the second conductor layer; the third interlayer connection conductor includes, in the thickness direction, a fifth portion, a sixth portion having a lower conductivity than the fifth portion, and a seventh portion having a higher conductivity than the sixth portion; one end of the fifth portion is joined to the fifth conductor layer, and the other end of the fifth portion is joined to one end of the sixth portion; the other end of the sixth portion is joined to one end of the seventh portion; the other end of the seventh portion is joined to the sixth conductor layer; The height of the first portion is A １ , the height of the second portion is B １ , the height of the fifth portion is A ３ , the height of the sixth portion is B ３ , the height of the seventh portion is C ３ , the height of the first interlayer connection conductor is T １ , the height of the third interlayer connection conductor is T ３ When T １ <T ３ , and B １ / A １ >B ３ / (A ３ +C ３ ) relationship holds true for a circuit board.

13. The height B of the second portion １ is the height B of the sixth portion ３ 13. The circuit board according to claim 11 or 12, wherein the thickness is equal to half of the thickness of the circuit board.

14. Height A of the fifth portion ３ is the height C of the seventh portion ３ 13. The circuit board according to claim 11 or 12, which is equivalent to

15. 13. The circuit board according to claim 11, wherein a diameter of the first interlayer connection conductor is smaller than a diameter of the third interlayer connection conductor.

16. 13. The circuit board according to claim 1, 2, 11 or 12, wherein the insulating layer is mainly composed of a thermoplastic resin.