JP2022083748A - Wiring board - Google Patents

Abstract

To provide a wiring board with good high frequency characteristics.SOLUTION: A wiring board 100 according to an embodiment includes an inner layer portion 10 having a first surface 10F and a second surface 10S opposite to the first surface 10F and having a first insulating layer 11 and a first conductor layer 12 alternately laminated, and an outer layer portion 20 formed on the first surface 10F and the second surface 10S, and having a second insulating layer 21 and a second conductor layer 22 alternately laminated. The first insulating layer 11 is formed by using a core material impregnated with a thermoplastic resin, and the second insulating layer 21 is formed by using a film-shaped thermosetting resin.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wiring board.

Patent Document 1 discloses a printed circuit board having a multi-layered build-up layer on both sides of the core layer. The core layer has an insulating layer formed of a carbon fiber reinforced resin obtained by impregnating a carbon fiber material with a resin composition such as an epoxy resin. Further, the build-up layer has an insulating layer made of, for example, an epoxy resin.

Japanese Unexamined Patent Publication No. 2008-10884

In the printed circuit board of Patent Document 1, an epoxy resin, which is a thermosetting resin having a relatively large dielectric constant and dielectric loss tangent, is used. It is considered that the transmission loss (dielectric loss) in the insulating layer is relatively large in the transmission of high frequency signals.

The wiring board of the present invention has a first surface and a second surface opposite to the first surface, and has an inner layer portion including a first insulating layer and a first conductor layer that are alternately laminated, and the first surface. And an outer layer portion including a second insulating layer and a second conductor layer formed on the second surface and alternately laminated. The first insulating layer is formed by using a core material impregnated with a thermoplastic resin, and the second insulating layer is formed by using a film-shaped thermosetting resin.

According to an embodiment of the present invention, it is possible to provide a wiring board having good high frequency characteristics in which dielectric loss in transmission of a high frequency signal is suppressed.

The cross-sectional view which shows an example of the wiring board of one Embodiment of this invention. The cross-sectional view which shows the other example of the wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the wiring board of one Embodiment of this invention. The figure which shows an example of the manufacturing method of the wiring board of one Embodiment of this invention.

A wiring board according to an embodiment of the present invention will be described with reference to the drawings. The wiring board of the embodiment is composed of an inner layer portion and an outer layer portion formed on both sides of the inner layer portion in the thickness direction. The wiring board 100 of the example shown in FIG. 1 has a core layer 10 as an inner layer portion and a build-up layer 20 as an outer layer portion. The core layer 10 has a first surface 10F on one side in the thickness direction thereof and a second surface 10S on the other side opposite to the first surface 10F. The build-up layer 20 is formed on the first surface 10F side and the second surface 10S side of the core layer 10.

The core layer 10 is formed by alternately laminating a plurality of insulating layers (first insulating layer) 11 and conductor layers (first conductor layer) 12. The build-up layer 20 is composed of an insulating layer (second insulating layer) 21 and a conductor layer (second conductor layer) 22 that are alternately laminated. In the illustrated example, the core layer 10 is composed of five layers of the first insulating layer 11 and six layers of the first conductor layer 12. The build-up layer 20 includes the same number of second insulating layers 21 and conductor layers 22 on the first surface 10F side and the second surface 10S side, and the second insulating layer 21 of the three layers and the second of the three layers. It is composed of a conductor layer 22.

Due to the configuration in which the build-up layers 20 on both sides of the core layer 10 have the same layer structure (second insulating layer 21 and second conductor layer 22 having the same number of layers), thermal expansion from the center in the thickness direction of the wiring board 100 to both sides. The amounts may be substantially the same, and warpage that may occur when a temperature change occurs in the wiring board 100 may be suppressed. However, in the wiring board of the embodiment, the number of layers of the first insulating layer 11 and the first conductor layer 12 included in the inner layer portion (core layer) 10 and the second insulation included in the outer layer portion (build-up layer) 20. The number of layers of the layer 21 and the second conductor layer 22 is not limited to those described above. The core layer 10 and the build-up layer 20 may include any number of insulating layers 11, 21 and conductor layers 12, 22. The build-up layer 20 may have an insulating layer 21 and a conductor layer 22 having different numbers of layers on the first surface 10F side and the second surface 10S side of the core layer 10.

In the description of the wiring board 100, the side far from the center in the thickness direction of the core layer 10 is also referred to as "upper side", "outer side", or simply "upper", "outer", and is also referred to as "upper side" or "outer side" in the thickness direction of the core layer 10. The side closer to the center in is also referred to as "lower", "inner", or simply "lower", "inner". Therefore, in the description of the build-up layer 20, the side far from the formed surface (first surface 10F or second surface 10S) is referred to as "upper side", "outer side", or simply "upper", "outer". Will be done.

Each conductor layer (first conductor layer 12, second conductor layer 22) constituting the wiring board 100 is formed of any material having appropriate conductivity (for example, copper, nickel, etc.), and each has a desired conductor pattern. Is formed in. As will be described in detail later, the second conductor layer 22 is formed to have a thickness smaller than that of the first conductor layer 12, and the second conductor layer 22 constituting the build-up layer 20 has a core layer 10. It has a wiring pattern that is finer than that of the constituent first conductor layer 12.

The conductor layers 12 and 22 are formed by, for example, a metal foil layer (preferably copper foil), a metal film layer (preferably a non-electrolytic copper plating film), an electrolytic plating film layer (preferably an electrolytic copper plating film), or a combination thereof. Can be configured. In the illustrated example, the first conductor layer 12 constituting the core layer 10 has three layers of a metal foil layer 12a, a metal film layer (electroless plating film) 12b, and an electrolytic plating film layer 12c. The first conductor layer 12 constituting the first surface 10F and the second surface 10S of the core layer 10 is a metal film layer 12a, a metal film layer 12b, and an electrolytic plating film layer 12c, and further on the upper side thereof. It has a five-layer structure including 12d and an electrolytic plating film layer 12e. The second conductor layer 22 constituting the outer layer portion (build-up layer) 20 has a two-layer structure including the metal film layer 22b and the electrolytic plating film layer 22c.

The core layer 10 is for connecting the first conductor layer 12 that penetrates the entire thickness direction and constitutes the first surface 10F and the first conductor layer 12 that constitutes the second surface 10S on the opposite side. Includes conductor 13. In the illustrated example, the connecting conductor 13 is formed by a metal film layer 12b and an electrolytic plating film layer 12c that cover the inner wall of the through hole 13h penetrating the core layer 10 from the first surface 10F side toward the second surface 10S. It contains a conductor film to be formed and a filler 13f that fills the inside of the conductor film.

The metal film layer 12b and the electrolytic plating film layer 12c constituting the connecting conductor 13 are integrally formed with the first conductor layer 12 constituting the first surface 10F and the second surface 10S. The filler 13f can be formed, for example, by using an electrically insulating resin material. The filler 13f may be a conductive paste containing conductive particles or a solidified product of conductive ink.

The connecting conductor 13 has substantially the same cross-sectional shape and dimensions in the thickness direction of the core layer 10. The connecting conductor 13 is connected to any first conductor layer 12 in the core layer 10 in addition to the first conductor layer 12 constituting the first surface 10F and the first conductor layer 12 constituting the second surface 10S. Can be done. In the illustrated example, the connecting conductor 13 is connected to the six layers of the first conductor layer 12 of the core layer 10. A metal film layer 12d and an electrolytic plating film layer 12e are formed on the end face of the filler 13f of the connecting conductor 13 so as to cover the filler 13f.

The second insulating layer 21 included in the build-up layer 20 includes a via conductor 23 that penetrates the second insulating layer 21 and connects the conductor layers formed on both sides thereof. The via conductor 23 is a so-called filled via, which includes a metal film layer 22b that covers the inner wall of the through hole 23h and an electrolytic plating film layer 22c formed by using the metal film layer 22b as a feeding layer, and includes the via conductor 23. 2 It is integrally formed with the second conductor layer 22 formed on the insulating layer 21.

The wiring board 100 has a coating layer 24 formed on the build-up layer 20. The coating layer 24 can be a solder resist layer. The coating layer 24 is formed by using, for example, an epoxy resin or a polyimide resin. The coating layer 24 has an opening 24a, and the connection pad 22p included in the second conductor layer 22 on the outermost surface (outermost side) of the wiring board 100 is exposed from the opening 24a. For example, an electronic component such as a semiconductor element or an external electric circuit board (not shown) may be mounted on the surface of the wiring board 100 via a connection pad 22p. The connection pad 22p may be electrically connected to a connection terminal of an electronic component or the like via a conductive connection member such as solder.

The first insulating layer 11 constituting the inner layer portion (core layer) 10 of the wiring board 100 and the second insulating layer 21 constituting the outer layer portion (build-up layer) 20 are formed by using an electrically insulating resin material. It is a resin insulating layer to be made. As the resin material constituting the first insulating layer 11, a thermoplastic resin having a relatively low dielectric constant and dielectric loss tangent is used. On the other hand, as the resin material constituting the second insulating layer 21, a thermosetting resin having relatively high heat resistance is used. By having such a configuration, as will be described in detail later, the wiring board 100 can have good high frequency characteristics (high frequency signal transmission characteristics), and at the same time, the occurrence of defects such as peeling is suppressed. Can have high reliability.

When the insulating layer constituting the wiring board has a relatively high value of dielectric constant and dielectric loss tangent, the dielectric loss (transmission loss) of the high frequency signal transmitted by the conductor layer in the wiring board is relatively large. The dielectric loss tends to increase as the frequency of the signal is high, and the dielectric loss can be remarkable particularly when a high frequency signal in the microwave or millimeter wave region is transmitted. To solve such a problem, in the wiring board of the present embodiment, a thermoplastic resin having a relatively low dielectric constant and dielectric loss tangent is used for the core insulating layer 11 constituting the core layer 10. Therefore, it is possible to provide a wiring board 100 having good high frequency characteristics in which the dielectric loss in the core layer 10 is suppressed to be relatively small.

The thermoplastic resin is a resin that exhibits plasticity when heated to the vicinity of the glass transition point. Therefore, when the outermost insulating layer of the wiring board is made of a thermoplastic resin, there is a defect such as peeling between the conductor layer and the insulating layer when electronic components are mounted on the surface of the wiring board. May occur. Specifically, when an electronic component is mounted via a connection pad formed on the outermost surface of a wiring board, the hardness of the insulating layer is reduced by the heat applied when the connection member such as solder is mounted, and the electronic component is mounted. The stress at the time of placing the solder may cause peeling between the insulating layer and the connection pad or the like. To solve such a problem, in the present embodiment, the insulating layer 21 of the outer layer portion 20 is formed of a thermosetting resin having a relatively high heat resistance. Therefore, deformation of the second insulating layer 21 is unlikely to occur when an electronic component is mounted, and therefore, the occurrence of peeling between the second insulating layer 21 and the second conductor layer 22 (connection pad 22p) can be suppressed.

Examples of the thermoplastic resin used for the first insulating layer 11 constituting the core layer 10 include polyetheretherketone resin (PEEK), polyetherimide resin (PEI), polyethylene resin (PE), and fluoroethylene resin (PTFE). , Liquid liquid polymer (LCP), etc. are exemplified.

Examples of the thermosetting resin used for the second insulating layer 21 include a thermosetting polyimide resin, an epoxy resin, and a bismaleimide triazine resin (BT resin). Among these, a bismaleimide triazine resin having a relatively small dielectric constant and dielectric loss tangent can be preferably used. In addition to the core layer 10, the build-up layer 20 also suppresses dielectric loss of high-frequency signals, and can provide a wiring board 100 having good high-frequency characteristics. Further, the thermosetting resin used for the second insulating layer 21 has a glass transition temperature of the thermoplastic resin constituting the first insulating layer 11 from the viewpoint of suppressing deformation of the core layer 10 during the manufacture of the build-up layer 20. It is preferable to use a resin that can be cured at a lower temperature.

The first insulating layer 11 does not have to be composed only of the thermoplastic resin, and a composite material of the thermoplastic resin and the thermosetting resin may be used. For example, a composite material obtained by using a thermoplastic resin such as a polyphenylene oxide resin or a polybutadiene resin and a thermosetting resin such as an epoxy resin or a cyanate resin to form an interpenetrating polymer network structure resin (IPN) can also be used.

The first insulating layer 11 constituting the core layer 10 in the present embodiment contains a fibrous reinforcing material (core material) CR. Since the first insulating layer 11 contains the core material CR, the rigidity of the first insulating layer 11 is improved. Therefore, defects caused by deformation of the first insulating layer 11 (for example, the first conductor layer) when the build-up layer 20 is formed on the core layer 10 or when electronic components or the like are mounted on the connection pad 22p. The generation of (such as peeling between 12 and the first insulating layer 11) can be suppressed.

The core material CR contained in the first insulating layer 11 of the core layer 10 is a material having a relatively small value of dielectric constant and dielectric loss tangent from the viewpoint of maintaining good high frequency characteristics (low dielectric loss) in the core layer 10. Is preferably used. As the core material CR, for example, quartz glass fiber, NE glass fiber, D glass fiber, or aramid fiber such as polyparaphenylene phthalamide fiber and polyparaphenylene benzobisoxador fiber (PBO) can be preferably used.

On the other hand, the second insulating layer 21 constituting the outer layer portion (build-up layer) 20 of the wiring board 100 is formed by using a film-shaped thermosetting resin that does not contain a core material. The second insulating layer 21 can be formed relatively thin by having a structure that does not include a core material. Therefore, the via conductor 23 included in the second insulating layer 21 constituting the build-up layer 20 can be formed at a relatively narrow pitch, and the second conductor layer 22 formed on the second insulating layer 21 can be formed. Can be formed to have a relatively fine wiring pattern.

The first insulating layer 11 and the second insulating layer 21 may contain a filler. When the first insulating layer 11 and the second insulating layer 21 contain an electrically insulating filler, the coefficient of thermal expansion thereof may be reduced, and the occurrence of defects may be more effectively suppressed. Defects (generation of peeling, cracks, etc.) due to the difference in the coefficient of thermal expansion of each element forming the substrate due to heating in the forming process of the wiring board 100 can be suppressed. As the filler contained in the first insulating layer 11 and the second insulating layer 21, it is preferable to use a filler having a relatively small value of dielectric constant and dielectric loss tangent from the viewpoint of improving the high frequency characteristics of the wiring board 100. .. For example, a filler containing silicon oxide, boron nitride, or the like can be preferably used.

In the wiring board 100 of the embodiment, the first insulating layer 11 is formed by using a sheet (prepreg) in which the core material CR is impregnated with a thermoplastic resin. The second insulating layer 21 is formed by using a thermosetting resin film having no core material. Therefore, in the outer layer portion 20, it is possible to form the second insulating layer 21 which is thinner than the first insulating layer 11, and thus it is possible to form the plurality of via conductors 23 at a relatively narrow pitch. .. Further, the second conductor layer 22 having a two-layer structure of the metal film layer 22b and the electrolytic plating film layer 22c is a first conductor having a three-layer structure of the metal foil layer 12a, the metal film layer 12b, and the electrolytic plating film layer 12c. It can be formed to have a thickness smaller than layer 12. The second conductor layer 22 may have a thickness of 0.5 times or less that of the first conductor layer 12. Therefore, the wiring pattern of the second conductor layer 22 is formed relatively finely, and may have a wiring pattern finer than that of the first conductor layer 12.

Specifically, the second conductor layer 22 may have a fine wiring layer having an L / S of 15 μm / 15 μm or less. On the other hand, the first conductor layer 12 constituting the core layer 10 is a wiring layer having an L / S of 50 μm / 50 μm or more. That is, the second conductor layer 22 of the outer layer portion 20 may have a finer wiring pattern than the first conductor layer 12 of the inner layer portion 10. Electronic components having connection terminals having a narrower pitch can be mounted via the connection pad 22p, and the selection range of electronic components that can be mounted on the wiring board 100 can be expanded. In the illustrated example, the second conductor layer 22 has a fine wiring pattern in the two build-up layers 20 on both sides of the core layer 10. However, at least one of the two build-up layers 20 may have a second conductor layer 22 with a fine wiring pattern.

In the example shown in FIG. 1, the connecting conductor 13 connecting the first conductor layer 12 constituting the first surface 10F and the second surface 10S of the core layer 10 has substantially the same shape in the thickness direction of the core layer 10. It is formed in a through hole 13h having a cross-sectional shape of the same size. When the filler 13f filled in the through hole 13h and constituting the connecting conductor 13 is made of an insulating resin, the filler 13f is the same as the first insulating layer 11 from the viewpoint of improving the high frequency characteristics. It is preferable that a thermoplastic resin is used.

The connecting conductor 13 is not limited to the form of a through-hole conductor. In the example shown as the wiring board 100a in FIG. 2, the first conductor layer 12 constituting the first surface 10F and the second surface 10S of the core layer 10 has the form of a stack via in which the via conductors 13v are laminated in series. It is connected by a connecting conductor. With such a configuration, the adhesion between the first conductor layer 12 and the first insulating layer 11 may be improved due to the anchor effect between the via conductor 13v and the first insulating layer 11. The wiring board 100a shown in FIG. 2 has the same configuration as the wiring board 100 except that the configurations of the connecting conductors are different, and specific description of these similar configurations is omitted. ..

Next, the method for manufacturing the wiring board of the present embodiment will be described below with reference to FIGS. 3A to 3H, using the wiring board 100 shown in FIG. 1 as an example. First, the inner layer portion is formed. Two resin substrates 10a having the first conductor layer 12 formed on both surfaces of the first insulating layer 11 are prepared. FIG. 3A shows one of the two resin substrates 10a.

The resin substrate 10a is a double-sided metal-clad laminate (for example, both sides) in which a metal foil layer 12a is laminated on both sides of a first insulating layer 11 including a resin insulating layer in which a core material (reinforcing material) CR is impregnated with a thermoplastic resin. It is formed using a copper-clad laminate) as a starting material. First, the metal film layer 12b is formed on the surface of the metal foil layer 12a of the double-sided metal-clad laminate by electroless plating or sputtering. Then, after forming the electrolytic plating film layer 12c on the metal film layer 12b by electrolytic plating, the first conductor layer 12 having a desired conductor pattern is formed by using a subtractive method including etching using an appropriate mask or the like. It is formed. The first conductor layer 12 may be formed by using a semi-additive method (MSAP) using a metal foil.

Next, as shown in FIG. 3B, the two resin substrates 10a and the three prepregs 10p are arranged so as to be alternately overlapped with each other. One prepreg 10p is sandwiched between two resin substrates 10a, and further, the prepreg 10p is arranged outside each of the two resin substrates 10a. A metal foil layer 12a is arranged on the outer side of the prepreg 10p arranged on the outermost side. The three stacked prepregs 10p and the two resin substrates 10a are integrated into a multilayer by being collectively pressed. The prepreg 10p contains a core material CR impregnated with a thermoplastic resin, like the resin insulating layer constituting the first insulating layer 11 constituting the resin substrate 10a, and is integrated with the first core layer 10. The insulating layer 11 is configured.

Next, as shown in FIG. 3C, a through hole (through hole) 13h penetrating the metal foil 12a and the first insulating layer 11 of the fifth layer is drilled at a predetermined position by a cutting device such as a drill. It is formed. The through hole 13h may be formed by irradiation with a laser beam.

Next, as shown in FIG. 3D, after the through hole 13h is formed, the metal film layer 12b is formed on the inner wall surface of the through hole 13h and on the outermost metal foil 12a. The metal film layer 12b is formed by, for example, electroless plating or sputtering. Subsequently, the electrolytic plating film layer 12c is formed on the metal film layer 12b by electrolytic plating using the metal film layer 12b as a feeding layer. On the inner wall surface of the through hole 13h, a conductor film having a two-layer structure including a metal film layer 12b and an electrolytic plating film layer 12c and responsible for the conductivity of the connecting conductor 13 is formed.

Next, as shown in FIG. 3E, the hollow portion of the through hole 13h (the region defined by the conductor film having a two-layer structure including the metal film layer 12b and the electrolytic plating film layer 12c) is filled with the filling material 13f. .. For example, an insulating thermoplastic resin such as PEEK or PTFE is injected from one side or both sides of the opening of the through hole 13h. If necessary, the filler such as resin injected from one side of the through hole 13h may be sucked from the other side. Instead of the insulating resin, the through holes 13h may be filled with a conductive paste containing conductive particles such as silver particles.

Further, the metal film layer 12d and the electrolytic plating film layer 12e are sequentially formed on the electrolytic plating film layer 12c and the filler 13f. The metal film layer 12d and the electrolytic plating film layer 12e are formed, for example, in the same manner as the metal film layer 12b and the electrolytic plating film layer 12c. As a result, the metal foil layer 12a, the metal film layer 12b, the electrolytic plating film layer 12c, the metal film layer 12d, and the electrolytic plating film layer 12e constituting the first surface 10F and the second surface 10S of the core layer 10 The first conductor layer 12 having a five-layer structure is formed.

The first conductor layer 12 constituting the first surface 10F and the second surface 10S has a desired conductor pattern, for example, by etching with an etching mask having an opening at an appropriate position, as shown in FIG. 3E. Is patterned into. The first conductor layer 12 can be formed in this way using the subtractive method. The formation of the core layer 10 shown in FIG. 3E is completed.

Next, the insulating layer and the conductor layer are alternately laminated on the first surface 10F and the second surface 10S side of the core layer 10, and the build-up layer 20 constituting the outer outer layer portion of the core layer 10 is formed. As shown in FIG. 3F, a resin film containing a thermosetting resin containing no reinforcing material is arranged on the first surface 10F and the second surface 10S, and the second insulating layer 21 is formed by thermocompression bonding. Will be done.

A through hole 23h is formed at a position where the via conductor 23 is formed in the second insulating layer 21, for example, by irradiation with a carbon dioxide laser beam. A metal film layer 22b made of a conductor such as copper is formed on the inner wall of the through hole 23h and on the surface of the second insulating layer 21 by electroless plating or sputtering. The metal film layer 22b is used as a feeding layer, and each has a desired conductor pattern by electrolytic plating using a plating resist having an appropriate opening, and has a two-layer structure of the metal film layer 22b and the electrolytic plating film layer 22c. , The second conductor layer 22 and the via conductor 23 are formed. That is, the second conductor layer 22 and the via conductor 23 are formed by a semi-additive method (SAP method) that does not use a metal foil.

Further, as shown in FIG. 3G, in the same manner as the formation of the second insulating layer 21 and the second conductor layer 22 formed on the first surface 10F and the second surface 10S side closest to the core layer 10. The stacking of the second insulating layer 21 and the second conductor layer 22 is repeated to form the build-up layer 20. The second conductor layer 22 may be formed so that the L / S is 15 μm / 15 μm or less.

As shown in FIG. 3H, the covering layer 24 is formed on the build-up layer 20. The coating layer 24 has an opening 24a that exposes the connection pad 22p by, for example, forming a resin layer containing a photosensitive epoxy resin, a polyimide resin, or the like, and exposing and developing with a mask having an appropriate opening pattern. Is formed like this. By going through the above steps, the wiring board 100 of the example of FIG. 1 is completed. The connection pad 22p exposed from the opening 24a has a surface protective film made of Au, Ni / Au, Ni / Pd / Au, solder, heat-resistant preflux, etc. by electroless plating, solder leveler, spray coating, or the like. (Not shown) may be formed.

When the wiring board 100a shown in FIG. 2 is formed, in the formation of the core layer 10, the first insulating layer 11 and the first conductor layer 12 are replaced with the batch lamination of the resin substrate 10a and the prepreg 10p, respectively. A build-up method can be used in which the layers are sequentially laminated. Specifically, the first insulating layer 11 containing the via conductor 13v on both sides of the resin substrate connecting the first conductor layer 12 in which the via conductor 13v constituting the connecting conductor is formed on both sides thereof. The core layer 10 can be formed by repeating the lamination of the first conductor layer 12 and the first conductor layer 12.

The wiring board of the embodiment is not limited to the structure exemplified in each drawing and the structure and shape exemplified in the present specification. For example, when the filler 13f that fills the connecting conductor 13 is conductive, the first conductor layer 12 on the surface of the core layer 10 does not include the metal film layer 12d and the electrolytic plating film layer 12e. May be good. As the insulating resin constituting the first insulating layer 11 and the second insulating layer 21, a foamed porous body may be used. The plurality of first conductor layers 12 constituting the core layer 10 may have different thicknesses in the core layer 10, and the thickness of the plurality of second conductor layers 22 constituting the build-up layer 20 may be different. , Each may be different within the buildup layer 20.

100, 100a Wiring board 10 Core layer (inner layer)
11 1st insulation layer 12 1st conductor layer 12a Metal leaf layer 12b, 12d, 22b Metal film layer 12c, 12e, 22c Electroplating film layer 13 Connection conductor 13v, 23 Via conductor 20 Build-up layer (outer layer)
21 2nd insulation layer 22 2nd conductor layer 24 Coating layer CR core material

Claims (10)

An inner layer portion having a first surface and a second surface opposite to the first surface and having a first insulating layer and a first conductor layer alternately laminated.
An outer layer portion having a second insulating layer and a second conductor layer formed on the first surface and the second surface and alternately laminated.
It is a wiring board equipped with
The first insulating layer is formed by using a core material impregnated with a thermoplastic resin.
The second insulating layer is formed by using a film-like thermosetting resin. In the wiring board according to claim 1, the wiring pattern of the second conductor layer is formed more finely than the wiring pattern of the first conductor layer. In the wiring board according to claim 2, the line / space of the wiring pattern included in the second conductor layer is smaller than 15 μm / 15 μm. The wiring board according to claim 1, wherein the thickness of the second conductor layer is smaller than the thickness of the first conductor layer. The wiring board according to claim 4, wherein the thickness of the second conductor layer is 0.5 times or less the thickness of the first conductor layer. The wiring substrate according to claim 1, wherein the first conductor layer has a structure of three or more layers including a metal foil layer, a metal film layer, and an electrolytic plating film layer, and the second conductor layer. Has a two-layer structure including a metal film layer and an electrolytic plating film layer. The wiring board according to claim 1, wherein the inner layer portion has a connecting conductor for connecting the first conductor layer constituting the first surface and the first conductor layer constituting the second surface. The connecting conductor has a cross-sectional shape having substantially the same size in the thickness direction of the inner layer portion. The wiring board according to claim 1, wherein the inner layer portion has a connecting conductor for connecting the first conductor layer constituting the first surface and the first conductor layer constituting the second surface. The connecting conductor is composed of a plurality of via conductors laminated in series. The wiring substrate according to claim 1, wherein the thermoplastic resin is a polyetheretherketone resin (PEEK), a polyetherimide resin (PEI), a polyethylene resin (PE), a fluoroethylene resin (PTFE), or a liquid crystal polymer. (LCP) is included. The wiring substrate according to claim 1, wherein the thermosetting resin contains any one of a thermosetting polyimide resin, an epoxy resin, and a bismaleimide triazine resin (BT resin).

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