JP2023096710A - Wiring board and manufacturing method of wiring board - Google Patents

Abstract

To improve characteristics of a wiring board.SOLUTION: A wiring board 100 includes: a first laminate 1 consisting of conductor layers 11a and 11b and insulating layers 12a and 12b, which are laminated, and including a first region 1a and a second region 1b which are adjacent to each other; and a second laminate 2 including conductor layers 21a and 21b and insulating layers 22a and 22b, which are laminated, and overlapped with the first region 1a. The first laminate 1 has flexibility, the wiring board 100 comprises a flexible part 100F consisting of the second region 1b of the first laminate 1 and a rigid part 100R including the first region 1a of the first laminate 1 and the second laminate 2, and the second laminate 2 includes the conductor layer 21b including radiation elements 51 and 52 constituting an antenna 5.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wiring board and a method for manufacturing the wiring board.

Patent Document 1 discloses an antenna in which a rigid dielectric substrate is bonded onto a flexible dielectric laminate containing a radiating element.

JP 2020-178246 A

In the antenna disclosed in Patent Document 1, a rigid dielectric substrate is bonded to the entire surface of a flexible dielectric laminate. As a result, the flexibility of the antenna as a whole is reduced, and in spite of using a flexible dielectric laminate, there are cases where a sufficient degree of freedom in mounting the antenna cannot be obtained. Also, since the dielectric substrate does not include a conductor layer, the conductor pattern forming the circuit around the radiating element may not be arranged.

The wiring board of the present invention comprises: a first laminate comprising a laminated conductor layer and an insulating layer and having a first area and a second area adjacent to each other; a second laminate including layers and overlapping the first region. The first laminate has flexibility, and the wiring board includes a flexible portion including the second region of the first laminate, the first region of the first laminate and the second region of the first laminate. a rigid portion including a laminate, the second laminate including a conductor layer including a radiating element forming an antenna.

A method of manufacturing a wiring board according to the present invention comprises preparing a starting substrate having a first surface and a second surface opposite to the first surface, and having a first metal layer on the first surface; providing a release film partially on the first surface with the first metal layer interposed therebetween; forming a first insulating layer having a metal layer on a surface opposite to the starting substrate; forming a first groove extending from a second surface of the starting substrate to the first metal layer along an edge of the release film; and alternately stacking a predetermined number of second insulating layers and first conductor layers on the first insulating layer, thereby forming a first stack including the first insulating layer. a radiating element constituting an antenna by forming a body and alternately laminating a predetermined number of third insulating layers and second conductor layers on the second surface side of the starting substrate; and the starting substrate. and forming a second groove penetrating the second laminate and the first insulating layer to reach the second metal layer along the edge of the release film and by removing a predetermined portion of the second laminate that overlaps with the release film in a plan view, a portion of the first laminate that does not overlap with the second laminate is made flexible. includes doing and

According to the embodiments of the present invention, it is considered that a wiring board having a high degree of freedom regarding the form of mounting and excellent characteristics of the antenna and its peripheral circuit is provided.

1 is a cross-sectional view showing an example of a wiring board according to one embodiment of the present invention; FIG. FIG. 2 is a perspective view showing the wiring board in FIG. 1; FIG. 2 is an enlarged view of part IIB of FIG. 1; FIG. 4 is a cross-sectional view showing an example of a method for manufacturing a wiring board according to one embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of a method for manufacturing a wiring board according to one embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of a method for manufacturing a wiring board according to one embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of a method for manufacturing a wiring board according to one embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of a method for manufacturing a wiring board according to one embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of a method for manufacturing a wiring board according to one embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of a method for manufacturing a wiring board according to one embodiment of the present invention; FIG. 4 is a cross-sectional view showing an example of a method for manufacturing a wiring board according to one embodiment of the present invention; FIG. 4 is a cross-sectional view showing another example of the wiring board manufacturing method according to one embodiment of the present invention;

A wiring board and a method for manufacturing the wiring board according to one embodiment will be described with reference to the drawings. FIG. 1 shows a cross-sectional view of a wiring board 100 that is an example of a wiring board according to one embodiment. 2A is a perspective view schematically showing the wiring board 100, and FIG. 2B is an enlarged view of the IIB portion of FIG. Note that the wiring board 100 is merely an example of the wiring board of the present embodiment. For example, the number of conductor layers and insulation layers included in the wiring board of the embodiment is not limited to the number of conductor layers and insulation layers included in the wiring board 100 of FIG.

As shown in FIG. 1, the wiring board 100 includes a first laminate 1 including laminated conductor layers and insulating layers, and a second laminated body 1 including laminated conductor layers and insulating layers. a body 2; The second laminate 2 in the example of FIG. and a conductor layer 21a formed on each of the first surface 2a and the second surface 2b. The second laminate 2 further includes a plurality of insulating layers 22b and a plurality of conductor layers 21b laminated on the second surface 2b of the insulating layer 22a. Each of the plurality of insulating layers 22b and each of the plurality of conductor layers 21b are alternately laminated.

On the other hand, the first laminate 1 in the example of FIG. 1 includes an insulating layer 12a (first insulating layer) laminated on the first surface 2a of the insulating layer 22a and a conductor formed on the insulating layer 12a. It includes layer 11b. The first laminate 1 further includes a plurality of insulating layers 12b (second insulating layers) and a plurality of conductor layers 11a (first conductor layers) laminated on the insulating layer 12a and the conductor layer 11b. there is Each of the plurality of insulating layers 12b and each of the plurality of conductor layers 11a are alternately laminated.

The first laminate 1 has a first region 1a and a second region 1b adjacent to each other, as shown in FIGS. 1 and 2A. The second laminate 2 overlaps the first region 1a of the first laminate 1 in plan view. However, the second laminate 2 does not have a portion overlapping the second region 1b of the first laminate 1, and does not overlap the second region 1b in plan view. Note that "planar view" means viewing the wiring board 100 with a line of sight parallel to its thickness direction.

In the description of the embodiments, the side farther from the insulating layer 22a in the thickness direction of the wiring board 100 is also referred to as "outer", "upper" or "upper", or simply "upper", and the side closer to the insulating layer 22a , "inner", "lower" or "lower", or simply "lower". Furthermore, in each conductor layer, the conductor pattern included in each conductor layer, and each insulating layer, the surface facing away from the insulating layer 22a is also referred to as the "upper surface", and the surface facing the insulating layer 22a is also referred to as the "lower surface". is called Note that the thickness direction of the wiring board 100 is also referred to as the “Z direction”.

In the wiring board 100 in the example of FIG. 1, the insulating layer 22a is the thickest among the insulating layers included in the wiring board 100. As shown in FIG. In the first region 1a, the number of insulating layers 12a and 12b and conductor layers 11a and 11b formed on the first surface 2a of the insulating layer 22a and the number of conductor layers 11a and 11b formed on the second surface 2b of the insulating layer 22a The number of insulating layers 22b and conductor layers 21b are the same. The insulating layer 22a is located at the center of the layered structure of the wiring board 100 in the first region 1a. The insulating layer 22a and the conductor layers 21a on both sides thereof constitute the core substrate 20 of the wiring substrate 100 in the first region 1a. That is, the second laminate 2 includes a core substrate 20 positioned at the center of the laminate structure of the wiring substrate 100 in the first region 1a of the first laminate 1. As shown in FIG.

The wiring board 100 of FIG. 1 includes through-hole conductors 31 that connect the conductor layers 21a formed on the first surface 2a and the second surface 2b of the insulating layer 22a. Through-hole conductors 31 are formed integrally with two conductor layers 21a. The through-hole conductor 31 is formed along the inner wall of the through-hole penetrating the insulating layer 22a and has a cylindrical shape. The inside of the cylindrical through-hole conductor 31 is filled with a resin body 31a containing arbitrary resin such as epoxy resin.

The wiring board 100 of FIG. 1 further includes via conductors 32 that penetrate through the insulating layer 12a, each insulating layer 12b, and each insulating layer 22b and connect the conductor layers on both sides of each insulating layer. Via conductors 32 passing through insulating layer 12a connect conductive layer 21a and conductive layer 11b on first surface 2a of insulating layer 22a. Via conductors 32 passing through each insulating layer 12b connect the conductor layers 11b and 11a sandwiching each insulating layer 12b, or connect the conductor layers 11a sandwiching each insulating layer 12b. Via conductors 32 penetrating through each insulating layer 22b connect the conductor layers 21a and 21b sandwiching each insulating layer 22b, or connect the conductor layers 21b sandwiching each insulating layer 22b.

The wiring board 100 of FIG. 1 further includes a coating layer 41 covering the surface of the first laminate 1 opposite to the second laminate 2 and a surface of the second laminate 2 opposite to the first laminate 1. includes a covering layer 42 covering the . The covering layer 41 is provided with an opening 41a that exposes a portion of the conductor layer 11a immediately below the covering layer 41, and the covering layer 42 is provided with an opening that exposes the conductor layer 21b immediately below the covering layer 42. 42a is provided.

In the wiring substrate 100 of this embodiment, the first laminate 1 has flexibility. That is, each of the conductor layers 11a and 11b and the insulating layers 12a and 12b that constitute the first laminate 1 has flexibility so that they can be bent without being damaged. For example, each of these conductor layers and insulating layers constituting the first laminate 1 is made of a material that can have such flexibility and has a thickness that does not hinder flexibility. The first laminate 1 may be formed with the intention of being actively bent. For example, each insulating layer and each conductor layer constituting the first laminate 1 are made of a material used for an insulating layer and a conductor layer constituting a general flexible printed circuit board (FPC). It may be formed to have a thickness similar to that of the layer and the conductor layer. Each thickness of the insulating layer 12a and each insulating layer 12b is, for example, about 10 μm to 100 μm. The thickness of the first laminate 1 is, for example, about 50 μm to 500 μm. In the description of the embodiments, both “flexible” and “flexible” mean that an object (for example, the first laminate 1) can be bent once at an angle of 20° or more without causing damage inside it. It means flexibility to the extent that it can be bent at any of the above positions.

On the other hand, the second laminate 2 has higher rigidity than the first laminate 1 . The second laminate 2 has at least the rigidity to the extent that it is not significantly and easily deformed by an external force that can be assumed in actual use. Any one or all of the insulating layers 22a, 22b and the conductor layers 21a, 21b constituting the second laminate 2 are formed so that the second laminate 2 as a whole can have such rigidity. For example, each insulating layer and each conductor layer constituting the second laminate 2 are made of a material used for an insulating layer and a conductor layer constituting a general rigid wiring board. It may be formed to have a thickness similar to that of the conductor layer. The thickness of each insulating layer 22b is, for example, about 10 μm to 100 μm. Also, the thickness of the insulating layer 22a is, for example, about 100 μm to 1000 μm. The thickness of the second laminate 2 is, for example, about 150 μm to 1200 μm. In addition, the "rigidity" of the second laminate 2 is the non-deformability to the extent that it cannot be bent at an angle of 5 ° or more without damaging the conductor layers and insulating layers inside the second laminate 2 ( (difficult to bend).

As described above, the second laminate 2 overlaps only the first region 1a of the first laminate 1 and does not overlap the second region 1b. That is, the first laminate 1 constitutes the wiring board 100 alone in the second region 1b. Therefore, the wiring board 100 can have the flexibility that the first laminate 1 has in the second region 1b of the first laminate 1 . On the other hand, the wiring substrate 100 can have rigidity equal to or greater than that of the second laminate 2 at least in the first region 1a of the first laminate 1 . That is, the wiring board 100 has a flexible portion 100F including the second region 1b of the first laminate 1 and a rigid portion 100R including the first region 1a of the first laminate 1 and the second laminate 2. . Therefore, the wiring board 100 can be bent as necessary at the flexible portion 100F without causing damaging damage. Therefore, it is considered that the wiring board 100 can be easily arranged on an installation surface having a curved portion, and the degree of freedom in the mounting form is high.

In particular, in the wiring board 100, as shown in FIG. 2A, the boundary line B between the rigid portion 100R and the flexible portion 100F in a plan view extends in one direction (X direction in the example of FIG. 2A) along a plane perpendicular to the Z direction. ) crosses the wiring board 100 . Therefore, the wiring board 100 can be easily bent along an arbitrary straight line that does not intersect the boundary line B between the rigid portion 100R and the flexible portion 100F in plan view, for example, along a straight line parallel to the boundary line B.

Each conductor layer (conductor layers 11a, 11b, 21a, 21b) constituting the first laminate 1 or the second laminate 2 may include any conductor pattern. In particular, the wiring board 100 of the embodiment includes a conductor pattern forming the antenna 5 in the second laminate 2 . In the example of FIG. 1, the outermost two conductor layers 21b among the plurality of conductor layers 21b constituting the second laminate 2 are conductor pads (first radiation element 51 and second radiation element) functioning as radiation elements of the antenna 5. 2 radiating elements 52). The outermost conductor layer 21 b includes a second radiation element 52 , and the lower conductor layer 21 b adjacent to the conductor layer 21 b includes a first radiation element 51 . The antenna 5 is composed of the first radiation element 51 and the second radiation element 52 . Thus, in the present embodiment, the second laminate 2 includes the conductor layer 21b including the radiation element 51 forming the antenna 5. As shown in FIG.

An insulating layer 22b is interposed between the first radiating element 51 and the second radiating element 52, and the first radiating element 51 and the second radiating element 52 face each other with the insulating layer 22b interposed therebetween. The first radiating element 51 and the second radiating element 52 may expand the frequency band of the high frequency signal radiated from the antenna 5 by electromagnetically coupling with each other. In the example of FIG. 1, the second radiating element 52 is covered with the covering layer 42 .

A signal to be transmitted from the antenna 5 is transmitted to the first radiation element 51 from another conductor pattern of the wiring board 100 . Also, an external signal received by antenna 5 is transmitted to another conductor pattern in wiring board 100 via first radiation element 51 . That is, the first radiation element 51 in the example of FIG. 1 is a feeding element to which an electric signal is to be supplied in the antenna 5 or to induce an electric signal based on external radio waves. On the other hand, in the example of FIG. 1, the second radiating element 52 is a parasitic element that is insulated from conductors other than the second radiating element 52 and is not energized from other conductors.

As in the example of FIG. 1, the first radiating element 51 can be connected to the conductor layers 21b and 21a in the second laminate 2 via the via conductors 32 . In the wiring board 100, since the second laminate 2 includes a conductor layer, a circuit element that is preferably arranged near the antenna 5, for example, can be arranged using the conductor pattern of the conductor layer 21b. For example, by forming passive elements such as capacitors and coils with the conductor pattern of the conductor layer 21a, these passive elements can be arranged in the vicinity of the antenna 5 in some cases. By doing so, favorable characteristics of the transmit/receive circuit including the antenna 5 may be obtained. According to this embodiment, it is possible to obtain a wiring board having good characteristics for the antenna and its peripheral circuits.

In addition, in this embodiment, the antenna 5 is configured within the second laminate 2 having such rigidity that it is not easily deformed by an external force that can be assumed in actual use. 52 is difficult to change. Therefore, it is considered that the characteristics of the antenna 5 are more stable than when the antenna is made of FPC or the like. In addition, compared to the case where the antenna is formed in the FPC composed of a conductive layer and an insulating layer, which tend to be thinly formed to have flexibility, the characteristics provided for the antenna 5, such as the gain bandwidth, are freer. considered to be high.

Furthermore, in the example of FIG. 1, the conductor layers 11a and 11b forming the first laminate 1 and the conductor layers 21a and 21b forming the second laminate 2 are connected through the through-hole conductors 31. electrically connected. Therefore, the first radiating element 51 can also be electrically connected to the conductor layers 11a and 11b in the first laminate 1 via a short path through the through-hole conductor 31. FIG. An electrical signal sent to or from the first radiation element 51 propagates through the conductor layers 11 a and 11 b in the first laminate 1 . A high-frequency signal having a frequency of, for example, several GHz or more can be applied to the first radiation element 51 that constitutes the antenna 5 . In the example of FIG. 1, the conductor layers 11a and 11b in the first laminate 1 and the conductor layers 21a and 21b in the second laminate 2 are connected by short paths through the through-hole conductors 31, so that reflection and High-frequency signal transmission characteristics with little attenuation may be obtained. For example, in comparison with a transmission line in which the wiring of an FPC equipped with an antenna and the wiring of a rigid wiring board formed separately from the FPC are connected by soldering or the like, the first laminate 1 and the second laminate in the example of FIG. It is considered that a transmission line having good transmission characteristics for high-frequency signals can be obtained between the laminated bodies 2 .

In the wiring board 100, the antenna 5 is composed of the first radiating element 51 and the second radiating element 52 provided on the outermost two conductor layers 21b of the plurality of conductor layers 21b. The first radiating element 51 and the second radiating element 52 can be provided in any conductor layer within the second laminate 2 . Also, between the first radiation element 51 and the second radiation element 52, only one insulating layer 22b may be interposed as in the example of FIG. You may have Further, the antenna 5 may be a so-called single-layer planar antenna configured only with the first radiating element 51 (feeding element) without the second radiating element 52 (parasitic element).

The insulating layer 22a and the insulating layer 22b included in the second laminate 2 are mainly made of any resin having appropriate insulating properties. Examples of resins forming the insulating layers 22a and 22b include thermosetting resins such as epoxy resins, bismaleimide triazine resins (BT resins), and phenolic resins. In the example shown in FIG. 1, the insulating layer 22a and the insulating layer 22b forming the second laminate each include a reinforcing member 221. In the example shown in FIG. Examples of the reinforcing material 221 include glass fiber and aramid fiber, but the reinforcing material 221 is not limited to these. When the insulating layers 22a and 22b contain the reinforcing material 221, the second laminate 2 tends to have sufficient rigidity. The insulating layers 22a and 22b may contain fillers (not shown) made of particles such as silicon dioxide and alumina. Physical properties such as thermal expansion coefficient and dielectric constant of the insulating layers 22a and 22b may be adjusted by selecting the material of the filler (not shown) and adjusting the content thereof.

The insulating layer 12a and the insulating layer 12b included in the first laminate 1 are also mainly made of any resin having appropriate insulating properties. The insulating layers 12a and 12b may contain thermosetting resin such as epoxy resin, polyimide (PI) resin, polyethylene terephthalate (PET) resin, for example. The insulating layers 12a, 12b may further include thermoplastic resins such as fluororesin, liquid crystal polymer (LCP), fluoroethylene (PTFE) resin, polyester (PE) resin, and modified polyimide (MPI) resin. good.

In the example shown in FIG. 1, the insulating layer 12a and the insulating layer 12b forming the first laminate 1 do not contain a reinforcing material. For example, since the insulating layers 12a and 12b do not contain a reinforcing material made of glass fiber or the like, the first laminate 1 is provided with appropriate flexibility. The insulating layers 12a and 12b may contain fillers (not shown) made of particles such as silicon dioxide and alumina. The coefficient of thermal expansion, dielectric constant, etc. of the insulating layers 12a and 12b may be adjusted by selecting the material of the filler (not shown) and adjusting the content of the filler.

The coating layer 41 and the coating layer 42 may also be made of any insulating resin. The coating layer 41 is formed of, for example, PI resin or PET resin, and may have a so-called coverlay function provided to protect the conductor layer in a general FPC. The coating layer 42 is made of, for example, a photosensitive epoxy resin or PI resin. The coating layer 42 can function as a solder resist on the surface of the wiring board 100 on the second laminate 2 side.

The conductor layers 11a and 11b, the conductor layers 21a and 21b, the through-hole conductors 31, and the via conductors 32 are made of any metal such as copper or nickel. Although each conductor layer is shown for simplicity in FIG. 1 as being composed of a single layer, specifically, two conductor layers, such as the conductor layers 11a, 11b, 21a shown in FIG. It can have a multi-layer structure including more layers. In the example of FIG. 2B, the conductor layer 21a is composed of a metal foil 210, a metal film 211, and a metal film 212. In the example of FIG. The conductor layer 11 b is composed of a metal foil 110 , a metal film 111 and a metal film 112 . On the other hand, the conductor layer 11a is composed of metal films 111 and 112 . Via conductors 32 penetrating each insulating layer 12b are formed by the metal films 111 and 112 . Although not shown in FIG. 2B, the conductor layer 21b (see FIG. 1) also has a three-layer structure similar to the conductor layer 11b or a two-layer structure similar to the conductor layer 11a.

Via conductors 32 passing through each insulating layer 22b (see FIG. 1) are made of conductors such as the first and second metal films 111 and 112 that constitute the conductor layer 11a. The through-hole conductors 31 (see FIG. 1) are formed by metal films 211 and 212 forming the conductor layer 21a. The metal films 111 and 211 are, for example, electroless plated films or sputtering films, and the metal films 112 and 212 are, for example, electrolytic plated films formed by electrolytic plating using the metal film 111 or the metal film 211 as a power supply layer. .

2B, the structures of the insulating layers 12a and 12b forming the first laminate 1 in the wiring board 100 of the example of FIG. 1 are described in detail. As shown in FIG. 2B, the insulating layers 12a and 12b have a two-layer structure including a first layer 121 and a second layer 122. As shown in FIG. In each of the insulating layer 12 a and each insulating layer 12 b , the first layer 121 is arranged below the second layer 122 , that is, on the second laminate 2 side with respect to the second layer 122 . Therefore, the first layer 121 is in contact with the conductor layer (for example, the conductor layer 21a for the insulation layer 12a) on the second laminate 2 side with respect to the insulation layer 12a and each insulation layer 12b.

On the other hand, the insulating layer 122 is arranged on the upper side of the first layer 121 in each of the insulating layer 12a and each insulating layer 12b, that is, on the opposite side of the first layer 121 from the second stacked body 2 side. The second layer 122 is laminated on the surface of the first layer 121 opposite to the second laminate 2 side in each of the insulating layer 12a and the insulating layers 12b. Therefore, the second layer 122 is in contact with the conductor layer (for example, the conductor layer 11b for the insulation layer 12a) on the side opposite to the second laminate 2 side with respect to the insulation layer 12a and each insulation layer 12b.

In each of the insulating layer 12a and each insulating layer 12b having a two-layer structure, the first layer 121 contains a thermosetting resin and the second layer 122 contains a thermoplastic resin. The thermosetting resin contained in the first layer 121 is, for example, the epoxy resin, PI resin, or PET resin described above. The thermoplastic resin contained in the second layer 122 is, for example, fluororesin, LCP, PTFE resin, PE resin, MPI resin, or the like described above.

Thermoplastic resins such as the above fluororesins, LCP, PTFE resins, PE resins, and MPI resins have relatively low dielectric constants of, for example, about 2 to 3 and low dielectric constants of about 1×10 ⁻⁴ to 1×10 ⁻³ . can have a loss tangent. Therefore, it is considered that the high-frequency signal propagating through the first laminate 1 has a small dielectric loss and is transmitted with high signal integrity (signal quality).

On the other hand, thermoplastic resins such as LCP may have lower adhesion to metals than thermosetting resins such as PI resins. Therefore, when the insulating layers 12a and 12b are formed by covering the conductor layers 11a and 11b or the conductor layer 21a with the second layer 122 mainly containing a thermoplastic resin, the conductor layers 11a and 11b or the conductor layer 21a and the insulating layer Interfacial delamination may occur between 12a and 12b.

However, in this embodiment, in the insulating layer 12a and each insulating layer 12b, the first layer 121 mainly containing the thermosetting resin covers the conductor layers 11a and 11b or the conductor layer 21a. Therefore, peeling between the conductor layers 11a and 11b or the conductor layer 21a and the insulating layers 12a and 12b is unlikely to occur. Note that peeling at the interface between the first layer 121 and the second layer 122 where the resins are mainly bonded together is considered less likely to occur than peeling at the interface between the metal and the resin. In addition, the adhesion between the second layer 122 and the conductor layer thereabove (for example, the conductor layer 11b formed on the second layer 122 constituting the insulating layer 12a) is affected by the roughening of the surface of the second layer 122. can be improved by Therefore, it is believed that interfacial delamination between the second layer 122 and its overlying conductor layer can be suppressed, for example, by such a roughening treatment.

Thus, according to the example shown in FIG. 2, in the first laminate 1, good transmission of high-frequency signals can be realized, and interfacial peeling between each conductor layer and each insulating layer is suppressed. It is considered that good quality can be obtained. In particular, in the example of FIG. 2B, all of the plurality of insulating layers (insulating layers 12a and 12b) included in the first stacked body 1 have a two-layer structure consisting of a first layer 121 and a second layer 122. As shown in FIG. Therefore, it is considered that good high-frequency signal transmission characteristics and good quality with little interfacial peeling can be obtained over the entire first laminate 1 . Note that all the insulating layers forming the first laminate 1 do not have to have a two-layer structure as in the example of FIG. It may have a two-layer structure including layer 122 .

In the example of FIG. 2B, among the plurality of insulating layers (insulating layer 12a and insulating layer 12b) included in the first stacked body 1, the insulating layer 12a (first insulating layer) formed closest to the second stacked body 2 is has the second layer 122 without the first layer 121 in the second region 1b. However, the first laminate 1 does not overlap the second laminate 2 in the second region 1b, so the second layer 122 of the insulating layer 12a is not in contact with any conductor layer. Therefore, interface separation between the insulating layer 12a and the conductor layer 21a cannot occur in the second region 1b.

In the example of FIG. 2B, the ratio of the thickness of the first layer 121 to the thickness of the second layer 122 in the insulating layer 12a is the ratio of the thickness of the first layer 121 to the thickness of the second layer 122 in the insulating layer 12b. is different from As described above, in the present embodiment, the thickness of the first layer 121 and the thickness of the second layer 122 in each of the plurality of insulating layers (the insulating layer 12a and the insulating layer 12b) of the two-layer structure constituting the first laminate 1 are The ratios may differ from each other. For example, the thickness of each of the first layer 121 and the second layer 122 can be selected according to the signal transmission quality required for the first laminate 1 . For example, the thickness of the second layer 122 may be 20% or more and 80% or less, or 60% or more and 80% or less of the thickness of each of the insulating layer 12a and the insulating layer 12b. Increasing the thickness of the second layer 122 may reduce the transmission loss of high frequency signals. Note that the thickness of the first layer 121 may be the difference between the thickness of the insulating layer 12 a or the insulating layer 12 b and the thickness of the second layer 122 .

A method of manufacturing a wiring board according to one embodiment will be described with reference to FIGS. 3A to 3H, taking as an example the case of manufacturing the wiring board 100 illustrated in FIG. Each component formed in the manufacturing method described below is formed using the material exemplified as the material of the corresponding component in the description of the wiring board 100 in FIG. 1, unless otherwise specified. obtain.

As shown in FIG. 3A, the wiring substrate manufacturing method of one embodiment includes preparing a starting substrate 200 having a first surface 2a and a second surface 2b opposite to the first surface 2a. contains. The starting substrate 200 includes an insulating layer 22a having a first side 2a and a second side 2b, with a metal layer 2aa (first metal layer) on the first side 2a and a metal layer 2bb on the second side 2b. ing. A part or all of the metal layer 2aa and the metal layer 2bb functions as the conductor layer 21a (see FIG. 1) in the wiring board 100 in the completed state. The insulating layer 22a is made of any insulating resin such as epoxy resin, BT resin, or phenol resin. In the example of FIG. 3A, the insulating layer 22a includes reinforcing material 221 made of glass fiber, for example.

The metal forming the metal layers 2aa and 2bb is, for example, copper or nickel. The metal layers 2aa and 2bb may be single layers or may have a multi-layer structure. Metal layers 2aa and 2bb may each have any metal pattern. Metal layer 2aa includes metal pads 2ab. The metal pads 2ab are provided in a region to be the flexible portion 100F (see FIG. 1) of the wiring board 100 in a completed state in a plan view (the region to be the flexible portion 100F of the wiring board 100 in a completed state and the rigid portion The regions to be 100R are hereinafter simply referred to as “flexible portion 100F” and “rigid portion 100R”, respectively, and are indicated by reference numerals “100F” and “100R” respectively in FIGS. 3A-3H).

The metal pad 2ab is provided such that a part of the outer edge of the metal pad 2ab is along the boundary line B on the rigid portion 100R side of the boundary line B (see FIG. 2) between the flexible portion 100F and the rigid portion 100R in plan view. (Border B is indicated by a black circle (dot) labeled B in FIGS. 3A-3H). When the insulating layer 22a has a rectangular planar shape, the metal pad 2ab is preferably formed to have an outer edge along three sides of the insulating layer 22a. By doing so, the flexible portion 100F that is easily bent in the completed wiring board 100 may be obtained.

In preparing the starting substrate 200, for example, a double-sided copper-clad laminate having an insulating layer 22 is prepared, and through-holes 311 are formed, for example, by drilling. For example, an electroless plated film that constitutes a part of each of the metal films 2aa and 2bb is formed on the inner wall of the through hole 331 and the surface of the double-sided copper-clad laminate. is used as a power supply layer to form an electrolytic plated film. After that, the electrolytic plated film or the like is patterned by wet etching or the like using an appropriate mask to form metal layers 2aa and 2bb having predetermined metal patterns. A through-hole conductor 31 is formed on the inner wall of the through-hole 331 . In the example of FIG. 3A, the inside of the through-hole conductor 31 is filled with a resin body 31a by injecting, for example, epoxy resin into the inside of the through-hole conductor 31 . For example, a starting substrate 200 with metal layers 2aa, 2bb is prepared in this way. The starting substrate 200 functions as the core substrate 20 (see FIG. 1) in the completed wiring substrate 100 .

As shown in FIG. 3B, the wiring board manufacturing method of the present embodiment includes providing a release film 6 on the first surface 2a of the insulating layer 22a via the metal layer 2aa. The release film 6 is partially provided on the first surface 2a of the insulating layer 22a. Specifically, the release film 6 is provided on the flexible portion 100F, that is, on the metal pad 2ab in the example of FIG. 3B in a plan view. For example, the release film 6 having substantially the same shape and size as the metal pad 2ab in plan view is formed. Preferably, release film 6 is formed so as not to protrude from the edge of metal pad 2ab along boundary line B. As shown in FIG. On the other hand, the release film 6 may be formed so as to protrude from the edge of the metal pad 2ab along the outer edge of the insulating layer 22a. If the outer edge of insulating layer 22a is exposed without being covered with metal pad 2ab, release film 6 is preferably formed to cover the exposed portion. Partial removal of the starting substrate 200 in a later process may be facilitated.

In the example of FIG. 3B , the release film 6 has an adhesive layer 61 directed toward the metal layer 2 aa and a release layer 62 laminated on the adhesive layer 61 . The adhesive layer 61 is made of a material that exhibits sufficient adhesiveness to a metal such as copper forming the metal layer 2aa or an epoxy resin. On the other hand, the release layer 62 is formed using a material such as epoxy resin, fluororesin, or LCP, which does not strongly adhere to the resin with which the release film 6 is covered in a later process. By providing such a release film 6, partial removal of the starting substrate 200, which will be described later, can be facilitated. PI resin is exemplified as the material of the adhesive layer 61 . Acrylic resin is exemplified as the material of the release layer 62 . For the release film 6, for example, two layers of resin layers made of materials for the adhesive layer 61 and the release layer 62 are sequentially formed on the first surface 2a of the insulating layer 22a and the entire surface of the metal layer 2aa, and unnecessary portions are removed. can be formed by

As shown in FIGS. 3B and 3C, the method for manufacturing a wiring board according to the present embodiment further includes the following steps: , forming an insulating layer 12a (first insulating layer). First, as shown in FIG. 3B, the resin sheet 121a is placed on the first surface 2a of the starting substrate 200 that is not covered with the release film 6. Then, as shown in FIG. A resin sheet 121a having a size that covers the entire surface of the first surface 2a that is not covered with the release film 6 is prepared and placed on the first surface 2a and the metal layer 2aa. The resin sheet 121a is provided on the rigid portion 100R in plan view. The resin sheet 121a may be arranged such that the edge of the resin sheet 121a overlaps the release film 6 at the boundary between the flexible portion 100F and the rigid portion 100R. The resin sheet 121a is a B-stage molded product made of insulating resin, and examples of the material include epoxy resin, PI resin, and PET resin. The resin sheet 121a may contain a thermosetting resin such as these exemplified resins.

Furthermore, a resin film 122a made of a film-shaped resin is laminated on the release film 6 and the resin sheet 121a. A metal foil 110 made of, for example, copper or nickel is further laminated on the surface of the resin film 122a opposite to the starting substrate 200 . Examples of the resin forming the resin film 122a include thermoplastic resins such as fluorine resin, LCP, PTFE resin, PE resin, and MPI resin. 3B, a film-shaped resin having a surface to which the metal foil 110 is bonded in advance may be laminated on the resin sheet 121a and the release film 6 as the resin film 122a.

In the example of FIG. 3B, a resin sheet 220 is laminated on the second surface 2b of the starting substrate 200. In the example of FIG. The resin sheet 220 is a molded article made of insulating resin in a B-stage state, and examples thereof include thermosetting resins such as epoxy resin, BT resin, and phenol resin. The resin sheet 220 may include a reinforcing member 221 made of glass fiber, for example, as in the example of FIG. 3B. A metal foil 210 made of, for example, copper or nickel is further laminated on the surface of the resin sheet 220 opposite to the starting substrate 200 . It should be noted that a sheet-shaped resin having a metal foil 210 bonded in advance to the surface thereof as in the example of FIG.

The starting substrate 200 and the release film 6, the resin sheet 121a, the resin film 122a, and the resin sheet 220 laminated on the first surface 2a or the second surface 2b thereof are heated and pressurized together with the metal foils 110 and 210. be. By heating and heating, the resin sheet 220 and the resin sheet 121a are bonded to the starting substrate 200, and the resin sheet 121a and the resin film 122a are bonded. Metal foil 110 and metal foil 210 are also bonded to resin film 122a and resin sheet 220, respectively. On the other hand, the resin film 122a and the release film 6 (specifically, its release layer 62) preferably adhere to each other without any gap.

As a result, an insulating layer 12a is formed on the first surface 2a of the starting substrate 200, as shown in FIG. 3C. The insulating layer 12a includes a first layer 121 made of a resin sheet 121a in a C-stage state and a second layer 122 made of a resin film 122a that is softened and then hardened again. An insulating layer 22b (third insulating layer) made of a resin sheet 220 in a C-stage state is formed on the second surface 2b of the starting substrate 200 .

In the example of FIG. 3C, a through hole 32a penetrating the insulating layer 12a and the metal foil 110, and a through hole 32a penetrating the insulating layer 22b and the metal foil 210 are formed. The through-holes 32a are formed at locations where the via conductors 32 (see FIG. 3D) penetrating the insulating layer 12a or the insulating layer 22b are formed. The through-holes 32a are formed, for example, by irradiating a laser beam such as a carbon dioxide laser or an excimer laser. Further, a metal film 111 is formed on the metal foil 110 and on the inner walls of the through holes 32a penetrating the insulating layer 12a by, for example, electroless plating or sputtering. In a similar manner, a metal film 211 is formed on the metal foil 210 and on the inner walls of the through holes 32a penetrating the insulating layer 22b.

As shown in FIG. 3D, the wiring board manufacturing method of the present embodiment further comprises forming a groove G1 (first groove) in the starting substrate 200 extending from the second surface 2b of the starting substrate 200 to the metal layer 2aa. contains. The groove G1 is formed along the edge of the release film 6 in plan view. The groove G1 is formed, for example, so that the groove G1 overlaps the outer edge of the release film 6 in plan view. A portion of the metal layer 2aa is exposed in the groove G1 by forming the groove G1. The groove G1 is formed by irradiation with laser light such as a carbon dioxide laser or a YAG laser. In this case, the metal layer 2aa (specifically, the metal pad 2ab) functions as a laser light stopper.

In the example of FIG. 3D, an insulating layer 22b is formed on the second surface 2b of the starting substrate 200 before forming the grooves G1. Therefore, a groove G1 is formed that also penetrates the insulating layer 22b. Forming the trench G1 in this manner may include penetrating the insulating layer 22b with the trench G1. The formation of the groove G1 separates the starting substrate 200 and the insulating layer 22b into the flexible portion 100B and the rigid portion 100R.

In the example of FIG. 3D, a metal film 112 is formed on a predetermined region on the metal film 111 and a metal film 212 is formed on a predetermined region on the metal film 211 before forming the groove G1. A via conductor 32 is formed inside the through hole 32a. The metal film 112 is formed in the formation area of the conductor pattern included in the conductor layer 11b (see FIG. 3E). A metal layer 113 (second metal layer) having a three-layer structure consisting of a metal foil 110 , a metal film 111 and a metal film 112 is provided on the surface of the insulating layer 12 a opposite to the starting substrate 200 . The metal film 112 forming the metal layer 113 is preferably formed in a predetermined region including a region overlapping the groove G1 in plan view. The metal pattern including the metal film 113 formed in the region overlapping with the groove G1 may function as a stopper for laser light used for forming the groove G2 (see FIG. 3G), which will be described later. On the other hand, the metal film 212 is preferably not formed in the region where the groove G1 should be formed.

The metal films 112 and 212 are formed by electroplating using the metal films 111 and 211 as power supply layers, respectively. The metal films 112, 212 are formed, for example, by pattern plating using a plating resist (not shown) with appropriate openings. After that, portions of the metal film 111 and the metal foil 110 that are not covered with the metal film 112 are removed by quick etching, for example. Similarly, portions of the metal film 211 and the metal foil 210 that are not covered with the metal film 212 are removed. As a result, the conductor layer 11b (see FIG. 3E) made of the metal layer 113 after part of the metal film 111 and the metal foil 110 are removed is obtained. Similarly, a conductor layer 21b (see FIG. 3E) made of a metal film 212 or the like is obtained. After that, a groove G1 is formed.

Note that the formation of the metal films 111, 112, 211, and 212 shown in FIGS. 3C and 3D may be omitted. That is, the metal layer 113 included in the insulating layer 12a may have a three-layer structure as in the example of FIG. 3D, but may include only one layer (for example, the metal foil 110). The metal layer 113 consisting only of the metal foil 110 may be removed by etching, for example. A metal pattern that can serve as a laser light stopper is left behind. On the other hand, if the metal films 211 and 212 are not formed, the metal foil 210 may be entirely removed by etching or the like, for example, before forming the grooves G1.

As shown in FIG. 3E, the wiring board manufacturing method of the present embodiment may further include removing a portion of the metal layer 2aa that overlaps the groove G1. Specifically, in the example of FIG. 3E, part of the metal pad 2ab is removed. This portion of the metal layer 2aa is removed, for example, by etching. Conductor layer 11b and conductor layer 21b may be masked during the removal of portions of metal layer 2aa. By removing the portion of the metal layer 2aa that overlaps with the groove G1, the metal pad 2ab can be separated into a portion on the flexible portion 100B side and a portion on the rigid portion 100R side. Also, the edge of the release film 6 is exposed in the groove G1. The conductor layer 11b is provided with a conductor pattern 11bb at a position overlapping with the groove G1. The conductor pattern 11bb can function as a stopper for laser light used for forming the groove G2 (see FIG. 3G) in a later step.

As shown in FIG. 3F, the wiring board manufacturing method of the present embodiment further comprises forming a predetermined number of insulating layers 12b (second insulating layers) and conductor layers 11a (first conductor layers) on the insulating layer 12a. ) to form a first stack 1 including insulating layers 12a. Furthermore, in the wiring board manufacturing method of the present embodiment, a predetermined number of insulating layers 22b (third insulating layers) and conductor layers 21b (second conductor layers) are further formed on the second surface 2a side of the starting substrate 200. It involves forming a second stack 2 comprising a starting substrate 200 by alternate stacking. As described above, the lowermost insulating layer 22b among the predetermined number of insulating layers 22b has already been formed before the formation of the groove G1 (see FIG. 3C). The formation of the first laminate 1 and the formation of the second laminate 2 may be performed simultaneously, or one of them may be performed first.

In the example of FIG. 3F, the first laminate 1 is formed by stacking five sets of insulating layers 12b and conductor layers 11a on the insulating layers 12a and conductor layers 11b. However, the number of insulating layers 12b and conductor layers 11a laminated to form the first laminate 1 is not limited to the example of FIG. 3F. Further, in the example of FIG. 3F, five sets of insulating layers 22b and conductor layers 21b are further formed on the insulating layers 22b and conductor layers 21b already formed in the steps up to the steps described with reference to FIG. 3E. The second laminate 2 is formed by laminating. However, the number of insulating layers 22b and conductor layers 21b laminated to form the second laminate 2 is not limited to the example of FIG. 3F.

In the example of FIG. 3F, similarly to the insulating layer 12a, an insulating layer 12b including a first layer 121 and a second layer 122 stacked on the first layer 121 is formed. The first layer 121 is formed, for example, by thermocompression bonding a resin film on the insulating layer 12a and the conductor layer 11b, or on the already formed insulating layer 12b and the conductor layer 11a. The second layer 122 is formed, for example, by thermocompression bonding a resin film onto the first layer 121 .

Thermosetting resins such as epoxy resin, PI resin, and PET resin are exemplified as the material of the resin film used to form the first layer 121 . Thermoplastic resins such as fluororesin, LCP, PTFE resin, PE resin, and MPI resin are exemplified as materials for the resin film used to form the second layer 122 . Laminating each of the predetermined number of insulating layers 12b in this way means forming the first layer 121 containing a thermosetting resin and forming the second layer 122 containing a thermoplastic resin on the first layer 121. Including laminating on top. By forming the second layer 122 containing a thermoplastic resin, good transmission characteristics of high-frequency signals may be obtained in the conductor layer 11a. Also, by forming the first layer 121 containing a thermosetting resin as a base for the second layer 122, good adhesion may be obtained between the conductor layer 11b or between the conductor layer 11a and the insulating layer 12b.

Each insulating layer 12b is provided with through holes at positions where the via conductors 32 are to be formed, and each conductor layer 11a having a desired conductor pattern is formed by, for example, a semi-additive method that does not use metal foil. In the through holes formed in each insulating layer 12b, via conductors 32 are formed along with the formation of each conductor layer 11a. The first laminate 1 is formed by alternately repeating the formation of the insulating layer 12a and the formation of the conductor layer 11a.

In this embodiment, a flexible first laminate 1 is formed. That is, the insulating layer 12a, each insulating layer 12b, each conductor layer 11a, and the conductor layer 11b are formed with materials and thicknesses determined so that the first laminate 1 has flexibility. In the state shown in FIG. 3F, since the entire first laminate 1 overlaps the second laminate 2, the first laminate 1 cannot be easily bent. It has the aforementioned "flexibility".

Each insulating layer 22b of the second laminate 2 further formed in the process shown in FIG. 3F is formed on the already formed insulating layer 22b and conductor layer 21b, for example, with reference to FIGS. 3B and 3C. It is formed by thermally compressing a resin sheet 220 (see FIG. 3B) in the same manner as in the above process. In the example shown in FIG. 3F, the insulating layer 22b further formed in the process shown in FIG. That is, forming the insulating layer 22b can include laminating a resin sheet including the reinforcing material 221 on the second surface 2b side of the starting substrate 200 .

In the example shown in FIG. 3F, among the plurality of insulating layers 22b forming the second stacked body 2, the insulating layer 22b formed after the formation of the groove G1, that is, two layers from the starting substrate 200 side in the example of FIG. The groove G1 is filled with the resin forming the insulating layer 22b of the pawl. That is, the resin softened during thermocompression bonding for forming the insulating layer 22b flows into the groove G1 to fill the groove G1. Since the second laminate 2 does not have cavities, it is considered that cracks and delamination are less likely to occur when the temperature changes.

Through-holes are formed in the formed insulating layers 22b at positions where the via conductors 32 are to be formed. Then, for example, by a semi-additive method that does not use metal foil, each conductor layer 21b having a desired conductor pattern is formed, and via conductors 32 are formed in the through holes formed in each insulating layer 22b. The second laminate 2 is formed by alternately repeating the formation of the insulating layer 22b and the formation of the conductor layer 21b.

In this embodiment, the second laminate 2 including the radiating element forming the antenna 5 is formed. In the example of FIG. 3F , among the plurality of conductor layers 21 b forming the second laminate 2 , the outermost two conductor layers 21 b have conductor pads (first radiation element 51 and second radiation element 51 ) functioning as radiation elements of the antenna 5 . Two radiating elements 52) are formed. A second radiating element 52, which is a parasitic element, is formed on the outermost conductor layer 21b. A first radiation element 51 is formed.

The first radiating element 51 and the second radiating element 52 are formed as the antenna 5 so as to have an appropriate shape and size capable of radiating and/or receiving radio waves in a desired frequency band. For example, each plating resist (not shown) used when each conductor layer 21b is formed by a semi-additive method using pattern plating is applied with the shape and size corresponding to the first radiation element 51 or the second radiation element 52. An aperture is provided having a shape and size that accommodates.

When the wiring board 100 in the example of FIG. 1 is manufactured, a coating layer 41 and a coating layer 42 are further formed. The coating layer 41 is formed, for example, by attaching a film made of PI resin or PET resin to the surface of the first laminate 1 opposite to the second laminate 2 side. As the coating layer 42, for example, a resin film made of epoxy resin, PI resin, or the like is formed by spray coating, curtain coating, or print coating. Openings are provided in the covering layers 41 and 42 by, for example, a photolithographic technique.

As shown in FIG. 3G, the wiring board manufacturing method of the present embodiment further includes forming a groove G2 (second groove) penetrating through the second laminate 2 and the insulating layer 12a. A groove G2 is formed that reaches the conductor layer 11b made of the metal layer 113 (see FIG. 3D). The groove G2 is formed along the edge of the release film 6 in plan view. The groove G2 may be formed so as to trace the groove G1 (see FIG. 3F) filled with the insulating layer 22b in the second stacked body 2. As shown in FIG. The groove G2 may be formed so as to remove the resin filling the groove G1. The formation of the groove G2 separates the second laminate 2 into the flexible portion 100F and the rigid portion 100R. Also, the release film 6 and the first layer 121 of the insulating layer 12a are separated. A portion of the conductor layer 11b that overlaps with the groove G2 (conductor pattern 11bb in FIG. 3G) is exposed in the groove G2. The groove G2 can be formed by, for example, laser light irradiation using a carbon dioxide laser or a YAG laser. The conductor pattern 11bb of the conductor layer 11b can function as a laser light stopper.

As shown in FIG. 3H, the wiring board manufacturing method of the present embodiment includes removing a predetermined portion (removed portion R) of the second laminate 2 that overlaps the release film 6 in plan view. there is The method for manufacturing a wiring board according to the present embodiment includes making a portion of the first laminate 1 that does not overlap with the second laminate 2 flexible by removing the portion R to be removed. That is, as described above, since the first laminate 1 alone is formed to have flexibility, the second laminate 2 of the first laminate 1 can be removed by removing the portion R to be removed. The portion that no longer overlaps with the edge is in a state where it can be easily bent. That is, the portion of the first laminate 1 that no longer overlaps with the second laminate 2 is released from the restraint of the second laminate 2 and exhibits its original flexibility. A flexible portion 100F of the wiring board 100, which consists of a portion of the first laminate 1 that does not overlap with the second laminate 2, and a portion of the first laminate 1 that overlaps with the second laminate 2 and the second laminate. A rigid portion 100R of the wiring board 100, which is composed of the body 2, is obtained.

The part to be removed R can be removed by any method. For example, the part to be removed R is attracted to an attraction jig (not shown) or the like and separated from the first laminate 1 . Further, the adhesion between the portion to be removed R and the first laminate 1 may be weakened by applying ultrasonic waves, and the two may be separated from each other.

In the example of FIG. 3H, the release film 6 is removed together with the portion R to be removed. As described above, the adhesive layer 61 of the release film 6 is made of a material having sufficient adhesion to metal, epoxy resin, or the like, while the release layer 62 is made of resin such as epoxy resin, fluorine resin, or LCP. It is formed using a material that does not adhere strongly. Therefore, by separating the portion to be removed R from the first laminate 1, the release film 6 can also be removed. Removing the predetermined portion R to be removed in this manner may include removing the release film 6 together with the portion R to be removed. Separately from the removal of the part to be removed R, the peeling film 6 may be removed following the removal of the part to be removed, for example.

In the example of FIG. 3H, before removing the portion to be removed R and the peeling film 6, the portion of the conductor layer 11b (specifically, the conductor pattern 11bb) exposed in the groove G2 is etched, for example. removed by During this etching, the conductor layers 11a, 21b in the openings 41a, 42a can be protected by applying a suitable protective film made of eg PET resin to the surfaces of the covering layers 41, 42. FIG. By removing a portion of the conductor layer 11b exposed in the groove G2, it may be possible to reduce deterioration in appearance due to exposure of the surface of the oxidized conductor layer 11b. In the example of FIG. 3H, the conductor pattern 11bb overlapping the groove G2 is partially removed, but the entire conductor pattern 11bb may be removed. A portion of the conductor layer 11b exposed in the groove G2 may be left as it is without being removed. The wiring substrate 100 shown in FIG. 1 is completed through the above steps.

FIG. 4 shows another example of the wiring board manufacturing method of the present embodiment. In the example shown in FIG. 4, the groove G2 is formed by the time the outermost conductor layer 11a of the first laminate 1 and the outermost conductor layer 21b of the second laminate 2 are formed. . That is, the grooves G2 are formed before the exposed portions of the metal films 111 and 211 are removed in forming the conductor layers 11a and 21b by pattern plating. A portion of the conductor layer 11b is exposed on the bottom surface of the groove G2, as in FIG. 3G referred to earlier. Then, from the state shown in FIG. 4, the portion of the conductor layer 11b exposed in the groove G2 is removed by etching, for example. The exposed portion of the conductor layer 11b may be removed by etching along with the exposed portions of the metal films 111 and 211, respectively. Thereafter, coating layers 41 and 42 are formed while masking the groove G2. The portion to be removed R is then removed in a manner similar to that described with reference to FIG. 3H.

According to the wiring board and its manufacturing method of the present embodiment, the first laminate 1 having flexibility and the second laminate 2 having rigidity are partially laminated via the release film 6, and the core The wiring board 100 is formed like one build-up wiring board having a substrate. Therefore, the first laminate 1 and the second laminate 2 can include any electrical circuit made up of their respective conductor layers. Also, the antenna 5 formed in the second laminate 2 can be electrically connected to each conductor layer in the first laminate 1 through a short path via the via conductors 32 and the through-ball conductors 31 . A flexible portion (flexible portion 100F) is provided by removing a portion of the second laminate 2 that overlaps with the release film 6 . A portion (rigid portion 100R) including the antenna 5 other than the flexible portion has rigidity. Therefore, it is considered that a wiring board having a high degree of freedom in mounting form and having good characteristics for the antenna and its peripheral circuit can be provided.

The wiring substrates of the embodiments are not limited to those having the structures illustrated in each drawing, and the structures, shapes, and materials illustrated in this specification. The wiring board of the embodiment can have any layered structure including the first layered body and the second layered body. Each insulating layer forming the first laminate does not necessarily have a two-layer structure. The insulating layer forming the second laminate may contain a thermoplastic resin such as LCP. The insulating layer forming the second laminate may not contain the reinforcing material.

The method for manufacturing the wiring board of the embodiment is not limited to the method described with reference to each drawing. For example, each conductor layer can be formed by any method. Arbitrary steps may be added to the wiring board manufacturing method of the embodiment in addition to the steps described above, and some of the steps described above may be omitted.

100 Wiring board 100F Flexible part 100R Rigid part 1 First laminate 1a First region 1b Second region 11a Conductor layer (first conductor layer)
11b conductor layer 113 metal layer (second metal layer)
12a insulating layer (first insulating layer)
12b insulating layer (second insulating layer)
121 First layer 121a Resin sheet 122 Second layer 200 Starting substrate 2 Second laminate 20 Core substrate 21b Conductor layer (second conductor layer)
22a insulating layer 2a first surface 2aa metal layer (first metal layer)
2b Second surface 22b Insulating layer (third insulating layer)
220 resin sheet 221 reinforcing material 5 antenna 51 first radiation element 52 second radiation element 6 release film G1 groove (first groove)
G2 groove (second groove)
R part to be removed (predetermined part)

Claims (14)

a first laminate comprising a laminated conductor layer and an insulating layer and having a first region and a second region adjacent to each other;
a second laminate including laminated conductor layers and insulating layers and overlapping the first region;
A wiring board comprising
The first laminate has flexibility,
The wiring board has a flexible portion including the second region of the first laminate and a rigid portion including the first region of the first laminate and the second laminate,
The second laminate includes a conductor layer including a radiating element forming an antenna. The wiring board according to claim 1,
The insulating layer constituting the first laminate includes a first layer containing a thermosetting resin and a second layer laminated on the surface of the first layer opposite to the second laminate side 2 has a layered structure,
The second layer contains a thermoplastic resin. The wiring board according to claim 2,
The first laminate includes a plurality of insulating layers,
All of the plurality of insulating layers included in the first laminate have the two-layer structure. The wiring board according to claim 3,
Among the plurality of insulating layers included in the first stacked body, the first insulating layer formed closest to the second stacked body does not have the first layer in the second region and is the second layer. have. The wiring board according to claim 1,
The insulating layer forming the first laminate does not contain a reinforcing material, and the insulating layer forming the second laminate contains a reinforcing material. 2. The wiring board according to claim 1, wherein a conductor layer forming said first laminate and a conductor layer forming said second laminate are electrically connected. 2. The wiring board according to claim 1, wherein said second laminate includes a core substrate positioned at the center of the laminate structure of said wiring board in said first region. providing a starting substrate having a first side and a second side opposite the first side, the starting substrate comprising a first metal layer on the first side;
providing a release film partially on the first surface through the first metal layer;
forming a first insulating layer having a second metal layer on the surface opposite to the starting substrate on the release film and on the first surface not covered by the release film;
forming a first groove extending from the second surface of the starting substrate to the first metal layer along the edge of the release film in the starting substrate;
forming a first laminate including the first insulating layer by alternately laminating a predetermined number of second insulating layers and first conductor layers on the first insulating layer;
By alternately laminating a predetermined number of third insulating layers and second conductor layers on the second surface side of the starting substrate, a second laminate including the radiating element constituting an antenna and the starting substrate is formed. forming;
forming a second groove extending through the second laminate and the first insulating layer and reaching the second metal layer along an edge of the peeling film;
making a portion of the first laminate that does not overlap with the second laminate flexible by removing a predetermined portion of the second laminate that overlaps with the release film in plan view; ,
A method of manufacturing a wiring board, comprising: 9. The method of manufacturing a wiring board according to claim 8, wherein laminating each of the predetermined number of second insulating layers includes forming a first layer containing a thermosetting resin; laminating a second layer comprising a second layer over the first layer. 9. The method of manufacturing a wiring board according to claim 8, further comprising removing a portion of said first metal layer overlapping said first groove. 9. The method of manufacturing a wiring board according to claim 8, wherein forming the third insulating layer includes laminating a resin sheet containing a reinforcing material on the second surface side of the starting substrate. A method for manufacturing a wiring board according to claim 8,
a bottom insulating layer, one of the predetermined number of third insulating layers, being laminated onto the second surface of the starting substrate prior to formation of the first grooves;
Forming the first trench includes penetrating the bottom insulating layer with the first trench. A method for manufacturing a wiring board according to claim 8,
Forming the first insulating layer includes placing a resin sheet containing a thermosetting resin on the first surface of the starting substrate that is not covered with the release film. 9. The method of manufacturing a wiring board according to claim 8, wherein removing said predetermined portion of said second laminate includes removing said peeling film together with said predetermined portion.

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