JP2020136484A - Wiring board - Google Patents

Abstract

To improve the transmission and reception quality of an antenna of a wiring board.SOLUTION: A wiring board 1 according to the present embodiment comprises: a first conductive layer 31 including a first radiation element 21 composing an antenna 2; a second conductor layer 32 including a second radiation element 22 composing the antenna 2 together with the first radiation element 21; two or more inter-layer insulation layers 4a interposed between the first conductor layer 31 and the second conductor layer 32. The wiring board 1 has: an antenna area A including the antenna 2; and a peripheral area P that is an area around the antenna area A in a plan view. The first conductor layer 31 and the second conductor layer 32 have, between them, a first interval in the antenna area A and a second interval in the peripheral area P, the first interval being shorter than the second interval.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wiring board.

Patent Document 1 discloses an electronic component module having an antenna element on one surface. The antenna element is formed on the surface of the second dielectric substrate and is electrically connected to the high frequency device mounted on the first dielectric substrate via a transmission line.

Japanese Unexamined Patent Publication No. 2005-86603

In the antenna provided in the electronic component module of Patent Document 1, for example, a signal having a frequency of several GHz or more is transmitted and / or received. High-frequency signals transmitted and received by antennas are susceptible to changes in the surrounding electromagnetic environment. For example, crosstalk with other conductor patterns on the wiring board may hinder proper transmission and reception of signals by the antenna.

The wiring substrate of the present invention includes a first conductor layer including a first radiating element constituting an antenna, a second conductor layer including a second radiating element constituting the antenna together with the first radiating element, and the first conductor. It includes two or more interlayer insulating layers interposed between the layer and the second conductor layer. The wiring board has an antenna region including the antenna and a peripheral region which is a region around the antenna region in a plan view, and the first conductor layer and the second conductor layer are the antenna. The region has a first spacing and a second spacing in the peripheral region between each other, the first spacing being shorter than the second spacing.

According to the embodiment of the present invention, the signal transmitted and received by the antenna of the wiring board can be appropriately transmitted and / or received while suppressing the increase in the size of the wiring board and reducing the influence of other signals. It is thought that it can be done.

The cross-sectional view which shows an example of the wiring board of one Embodiment of this invention. An enlarged view of Part II shown in FIG. The plan view of the antenna area and a part of the peripheral area in the wiring board of FIG. The plan view which shows the other example of the peripheral area in the wiring board of one Embodiment. FIG. 5 is a cross-sectional view showing another example of the interlayer insulating layer of the wiring board of one embodiment. FIG. 5 is a cross-sectional view showing an example of a starting board in the manufacture of the wiring board of one embodiment. The cross-sectional view which shows an example of the manufacturing process of the wiring board of one Embodiment. The cross-sectional view which shows an example of the formation of the 1st radiation element in the manufacturing of the wiring board of one Embodiment. FIG. 5 is a cross-sectional view showing an example of forming an interlayer insulating layer in the manufacture of a wiring board of one embodiment. FIG. 5 is a cross-sectional view showing an example of forming a second radiating element in the manufacture of the wiring board of one embodiment.

Next, a wiring board according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a cross-sectional view of a wiring board 1 which is an example of a wiring board of one embodiment. As shown in FIG. 1, the wiring board 1 includes two build-up layers (first build-up layer 11 and second build-up layer 12) including the same number of conductor layers as each other, and first and second build-up layers. It includes a core substrate 10 sandwiched between the build-up layers 11 and 12. The first build-up layer 11 includes a first conductor layer 31, a second conductor layer 32, and two conductor layers 3a between the first conductor layer 31 and the second conductor layer 32. The first build-up layer 11 includes a first radiating element 21 and a second radiating element 22 constituting the antenna 2. The second build-up layer 12 includes a third conductor layer 33 and three conductor layers 3b provided above the third conductor layer 33. In the description of the wiring board 1, the side far from the core board 10 in the thickness direction of the wiring board 1 is referred to as "upper side" or "upper side", or simply "upper side", and the side closer to the core board 10 is "lower side". Alternatively, it is also referred to as "downward" or simply "downward". Further, in each conductor layer and each insulating layer, the surface facing the side opposite to the core substrate 10 is also referred to as an "upper surface", and the surface facing the core substrate 10 side is also referred to as a "lower surface".

The first build-up layer 11 further includes first and second conductor layers 31, 32, and three interlayer insulating layers 4a interposed between the two conductor layers 3a, respectively. The first build-up layer 11 further includes a first insulating layer 41 provided on the side opposite to the interlayer insulating layer 4a side with respect to the first conductor layer 31. The first insulating layer 41 is an interlayer insulating layer interposed between the core substrate 10 and the first conductor layer 31. The second build-up layer 12 has three interlayer insulating layers 4b interposed between the third conductor layer 33 and the three conductor layers 3b, and a second layer insulating layer 4b interposed between the core substrate 10 and the third conductor layer 33. 2 Insulating layer 42 is included. The number of interlayer insulating layers 4a between the first conductor layer 31 and the second conductor layer 32 is not limited to three, and two or more between the first conductor layer 31 and the second conductor layer 32. Any number of interlayer insulating layers 4a may be provided. The second build-up layer 12 may also be provided with any number of interlayer insulating layers 4b other than the three.

The core substrate 10 includes an insulating layer (core layer) 40, and conductor layers 3c and conductor layers 3d formed on both surfaces of the insulating layer 40, respectively. The insulating layer 40 is formed with a through-hole conductor 10a that connects the conductor layer 3c and the conductor layer 3d.

Each conductor layer (first to third conductor layers 31 to 33 and conductor layers 3a to 3d) is shown to have a single layer structure in FIG. 1, but a plurality of layers such as two or three layers. Can have. Each of these conductor layers may have, for example, a metal foil layer, an electroless plating film layer, and an electroplating film layer. Each conductor layer can be formed, for example, with any metal such as copper, nickel, silver, palladium, alone or in combination.

The first and second insulating layers 41 and 42, the insulating layer 40, and the interlayer insulating layers 4a and 4b are formed by using an arbitrary insulating material. Examples of the insulating material include epoxy resin, bismaleimide triazine resin (BT resin), and phenol resin. Each insulating layer formed using these resins may contain a reinforcing material such as glass fiber or aramid fiber and / or an inorganic filler such as silica.

Each insulating layer includes via conductors 5a and 5b that connect the conductor layers on the upper surface side and the lower surface side, respectively. The first insulating layer 41 and the insulating layer 4a each include a via conductor 5a, and the second insulating layer 42 and the insulating layer 4b each include a via conductor 5b. The via conductors 5a and 5b are so-called filled vias formed by filling through holes penetrating each insulating layer with a conductor. The via conductors 5a and 5b are integrally formed with the respective upper conductor layers. Therefore, the via conductors 5a and 5b are formed of, for example, an electroless plating film and an electrolytic plating film made of copper, nickel, or the like. The through-hole conductor 10a is also formed of an electroless plating film and an electrolytic plating film made of copper, nickel, or the like.

The wiring board 1 of the example of FIG. 1 further includes a solder resist layer 6a formed on the first build-up layer 11 and a solder resist layer 6b formed on the second build-up layer 12. There is. The solder resist layers 6a and 6b are formed by using, for example, an epoxy resin or a polyimide resin. The solder resist layer 6a covers the second conductor layer 32.

The outermost conductor layer 3b of the second build-up layer 12 includes a connection pad 3b1 on which an electronic component (not shown) should be mounted. The solder resist layer 6b has an opening for exposing the connection pad 3b1.

The first conductor layer 31 includes a first radiating element 21. The second conductor layer 32 includes a second radiating element 22. The first radiating element 21 is composed of a conductor pattern formed on the first conductor layer 31. The second radiating element 22 is composed of a conductor pattern formed on the second conductor layer 32. The second radiating element 22 is covered with a solder resist layer 6a. An interlayer insulating layer 4a is interposed between the first radiating element 21 and the second radiating element 22. The first radiating element 21 and the second radiating element 22 face each other via the interlayer insulating layer 4a in order to form the antenna 2. The first radiating element 21 and the second radiating element 22 form an antenna 2 by being electromagnetically coupled to each other. The second conductor layer 32 further includes a conductor pattern 32a formed around the second radiating element 22. The conductive second radiating element 22 and the conductor pattern 32a have a creepage distance SD along the surface (upper surface) of the interlayer insulating layer 4a.

The first radiating element 21 has a recess 21b on the surface 21a facing the second radiating element 22. The first insulating layer 41 is connected to the lower surface of the first radiating element 21 (the surface on the first insulating layer 41 side), and is a via conductor connecting the first radiating element 21 and the conductor layer 3c (first via conductor 51). Includes. The first via conductor 51 is one of one or more via conductors 5a included in the first insulating layer 41. The recess 21b of the surface 21a is formed on the first via conductor 51. The recess 21b can increase the contact area between the first radiating element 21 and the insulating layer 4a, and may improve the adhesion between the two.

A signal to be transmitted from the antenna 2 or an external signal to be received by the antenna 2 is transmitted to the first radiating element 21. As described above, the first radiating element 21 may be a feeding element to which an electric signal should be supplied from the antenna 2 or to induce an electric signal based on an external radio wave.

The second radiating element 22 is insulated from a conductor other than the second radiating element 22, and the second radiating element 22 cannot be energized from other conductors. The second radiating element 22 may be a non-feeding element that is not energized when the antenna 2 is used, as in the example of FIG.

In the example of FIG. 1, the first radiating element 21 which is a feeding element is included in the first build-up layer 11, and the signal to be transmitted by the antenna 2 is transmitted from the second build-up layer 12 to the first radiating element 21. Is transmitted. Further, the signal received by the antenna 2 is transmitted from the first radiating element 21 to the second build-up layer 12. The third conductor layer 33 included in the second build-up layer 12 includes a signal transmission path 331 that transmits a transmission / reception signal of the antenna 2. The signal transmission line 331 preferably forms a strip line with the conductor layer 3b in the second build-up layer 12.

The second insulating layer 42 includes a second via conductor 52 that connects the signal transmission line 331 and the conductor layer 3d. The second via conductor 52 is one of one or more via conductors 5b included in the second insulating layer 42. The first via conductor 51 and the second via conductor 52 are electrically connected via the through-hole conductor 10a. As a result, the first radiating element 21 and the signal transmission line 331 are electrically connected. For example, a high frequency signal can be transmitted bidirectionally between the signal transmission line 331 and the first radiation element 21 via the second via conductor 52, the through-hole conductor 10a, and the first via conductor 51.

Although not shown, the signal transmission line 331 may be connected to the connection pad 3b1 via the via conductor 5b in the second build-up layer 12. In that case, a signal generated by an electronic component (not shown) mounted on the connection pad 3b1 can be transmitted from the antenna 2. Further, the signal received by the antenna 2 can be input to the electronic component mounted on the connection pad 3b1 and processed by the electronic component.

The first radiating element 21 is separated from the other conductor patterns of the first conductor layer 31. That is, in a plan view, a region without a conductor pattern is provided in the first conductor layer 31 around the first radiating element 21. The second radiating element 22 is also separated from the other conductor patterns of the second conductor layer 32, and a region without a conductor pattern is provided around the second radiating element 22 of the second conductor layer 32 in a plan view. ing. The "planar view" means that the wiring board 1 is viewed with a line of sight parallel to the thickness direction of the wiring board 1 with respect to the view when the wiring board 1 is viewed from the outside.

As in the example of FIG. 1, the wiring board 1 provided with the antenna 2 has an antenna region A including the antenna 2 and a peripheral region P which is a region around the antenna region A. The first radiating element 21 and the second radiating element 22 face each other in the antenna region A via the interlayer insulating layer 4a. The "antenna region A" is a region occupied by the first and second radiating elements 21 and 22 and the first and second radiating elements 21 in the first and second conductor layers 31 and 32 in a plan view. It is a region composed of a separated region around 22. The “separation region” is a region around the first and second radiating elements 21 and 22 in the first and second conductor layers 31 and 32, and is a region in which the conductor pattern is not provided.

As shown in FIG. 1, in the antenna region A, the conductor pattern of the two conductor layers 3a is not formed between each of the three interlayer insulating layers 4a. On the other hand, in the peripheral region P, conductor patterns provided in the two conductor layers 3a are interposed between the three interlayer insulating layers 4a. Therefore, the thickness of the first build-up layer 11 in the antenna region A is thinner than the thickness of the first build-up layer 11 in the peripheral region P. On the other hand, the thickness of the solder resist layer 6a in the antenna region A is thicker than the thickness of the solder resist layer 6a in the peripheral region P.

In the wiring board 1, the upper surface of the first insulating layer 41 and the upper surface of each of the three interlayer insulating layers 4a are not flat, and the upper surface of each insulating layer is from the boundary portion between the antenna region A and the peripheral region P to the antenna region A. It is curved toward the core substrate 10 side toward the center. That is, the upper surface of each insulating layer is recessed as a whole toward the core substrate 10 in the antenna region A.

Specifically, since the conductor pattern is not provided in most of the conductor layers 3c of the core substrate 10 in the antenna region A, the upper surface of the first insulating layer 41 is curved toward the core substrate 10. The upper surface of the interlayer insulating layer 4a on the first conductor layer 31 is curved under the influence of the curvature of the upper surface of the first insulating layer 41 (although the first radiating element 21 is provided on the first conductor layer 31). are doing. The upper surfaces of the other two of the three interlayer insulating layers 4a are further curved than the upper surfaces of the first insulating layer 41 because the conductor layer 3a is not provided with the conductor pattern in the antenna region A. That is, the curved upper surface of each of the three interlayer insulating layers 4a has a smaller radius of curvature as the distance from the core substrate 10 increases.

Further, in the wiring board 1, since the surfaces (upper surfaces) of the three interlayer insulating layers 4a are curved, the second radiating element 22 is curved so as to be convex toward the first radiating element 21. Further, since the upper surface of the first insulating layer 41 is also curved, the first radiating element 21 can also be curved toward the core substrate 10.

FIG. 2 shows an enlarged view of part II of FIG. In FIG. 2, the portion on the left side of the antenna region A in FIG. 2 is omitted. The first conductor layer 31 and the second conductor layer 32 are located between each other along the thickness direction of the wiring board 1 (hereinafter, the "thickness direction of the wiring board 1" is also simply referred to as the "Z direction"). The antenna region A has a first interval L1 which is a length. Further, the first conductor layer 31 and the second conductor layer 32 have a second interval L2 in the peripheral region P, which is a length between each other along the Z direction.

As shown in FIG. 2, the first interval L1 is shorter than the second interval L2. In other words, with respect to the distance between the facing surfaces (opposing surfaces) of the first conductor layer 31 and the second conductor layer 32, the distance in the antenna region A is shorter than the distance in the peripheral region P. For example, the distance between the first radiating element 21 and the second radiating element 22 in the Z direction is the conductor pattern 31a of the first conductor layer 31 and the conductor pattern 32a of the second conductor layer 32 provided in the peripheral region P, respectively. Is shorter than the Z-direction spacing.

In a wiring board including an element such as an antenna 2 that transmits and receives radio waves, such as the wiring board 1, high-frequency signals transmitted and received by the antenna are affected by, for example, crosstalk with other conductor patterns in the wiring board. easy. Further, even if the other conductor pattern is a conductor pattern such as a ground pattern in which a signal does not flow, the quality of the waveform of the high frequency signal may deteriorate due to the capacitive coupling between the conductor pattern and the antenna. Therefore, it is preferable that the antenna provided on the wiring board is arranged as far as possible from the surrounding conductor pattern. However, ensuring a long distance between the antenna and the surrounding conductor pattern may lead to an increase in the plane size of the wiring board (the length in each of the two directions orthogonal to each other along the plane orthogonal to the thickness direction). is there.

In the present embodiment, the distance between the first conductor layer 31 and the second conductor layer 32 in the antenna region A (first distance L1) is the distance between the two conductor layers 31 and 32 in the peripheral region P (second distance L2). ), That is, the first interval L1 and the second interval L2 are different from each other. In the example of FIG. 2, although the second radiating element 22 and the conductor pattern 32a in the peripheral region P are provided in the same second conductor layer 32, they are positioned in the Z direction (first conductor layer 31). Distance or height from the top surface of the Therefore, the creepage distance SD between the second radiating element 22 and the conductor pattern 32a is longer than the distance MD corresponding to the creepage distance SD in a plan view. The "distance corresponding to the creepage distance SD in the plan view" is the distance in the plan view between the facing portions of the second radiating element 22 and the conductor pattern 32a having the creepage distance SD between each other.

That is, in the present embodiment, as compared with the case where the distance between the first conductor layer 31 and the second conductor layer 32 does not differ between the antenna region A and the peripheral region P, the antenna 2 (in the example of FIG. 2, the second conductor layer 32). The radiating element 22) can be moved somewhat away from the surrounding conductor pattern (conductor pattern 32a in the example of FIG. 2). For example, it may be possible to reduce the influence of the surrounding conductor pattern on the antenna provided on the wiring board while reducing the expansion of the plane size of the wiring board. Alternatively, the planar size of the wiring board may be somewhat reduced without increasing the influence of the surrounding conductor pattern on the antenna. Therefore, this embodiment may contribute to appropriate transmission / reception of signals transmitted / received by the antenna and / or miniaturization of the wiring board.

The creepage distance SD between the second radiating element 22 and the conductor pattern (for example, the conductor pattern 32a) of the peripheral region P depends on the difference between the first spacing L1 and the second spacing L2. The difference (L2-L1) between the first interval L1 and the second interval L2 changes according to the first interval L1, and the ratio (L2-L1) / L1 is, for example, 0.05 or more and 0.30 or less. Is. The first interval L1 is the interval between the first conductor layer 31 and the second conductor layer 32 in the antenna region A, and in the antenna region A, only the interlayer insulating layer 4a is between the first conductor layer 31 and the second conductor layer 32. Intervene in. Therefore, the creepage distance SD can be adjusted by selecting the number of layers of the interlayer insulating layer 4a.

FIG. 3 shows a plan view of a part of the antenna region A and the peripheral region P in the wiring board 1 of FIG. FIG. 1 is a cross-sectional view including a cross section taken along the line II shown in FIG. In FIG. 3, the solder resist layer 6a of FIG. 1 is not shown. Also, for clarity, the dashed line indicating the first radiating element 21 is drawn slightly inside the second radiating element 22. In the example of FIG. 3, the conductor pattern 32a is provided in the peripheral region P and defines the boundary between the antenna region A and the peripheral region P. Further, the conductor pattern 32a surrounds the second radiating element 22 over the entire circumference of the second radiating element 22, and the peripheral region P surrounds the antenna region A. Note that FIG. 3 is only an example of the antenna region A. The shapes of the antenna region A and the peripheral region P are not limited to the example of FIG.

In the example of FIG. 3, the recess 21b on the surface of the first radiating element 21 is provided in the vicinity of one side in the planar shape of the first radiating element 21. As described above, the recess 21b is formed on the first via conductor 51 (see FIG. 1), and the transmission / reception signal is transmitted to or from the first radiation element 21 or from the first radiation element 21 via the first via conductor 51. Is transmitted. In the case of the arrangement of the recess 21b as in the example of FIG. 3, the feeding point (first via conductor 51) in the first radiating element 21 and the farthest edge of the first radiating element 21 from this feeding point. A long distance can be secured. By doing so, it is considered that the area of the first radiating element 21 can be effectively used for selecting the transmission / reception band of the antenna 2.

The conductor pattern 32a that defines the boundary between the peripheral region P and the antenna region A does not necessarily have to surround the antenna 2 over the entire circumference. If there is a discontinuity in the conductor pattern 32a around the antenna 2, for example, by the inner edge of the conductor pattern 32a adjacent to the antenna 2 and the extension line obtained by extrapolation and / or interpolation of the inner edge. A boundary between the peripheral region P and the antenna region A can be defined. Further, the wiring board 1 may have a peripheral region P only in a part of the circumferential direction around the antenna 2. For example, in the example of FIG. 3, the wiring board 1 may have peripheral regions P on only one or three of the right side, left side, upper side, and lower side of the second radiating element 22.

The plan view shown in FIG. 4 shows another example of the peripheral region P in the wiring board 1. In the example of FIG. 4, the inner edge 31b surrounding the first radiating element 21 in the conductor pattern 31a of the first conductor layer 31 (see FIG. 1) is located outside the inner edge 32b surrounding the second radiating element 22 in the conductor pattern 32a. ing. As described above, the inner edge 31b of the conductor pattern 31a and the inner edge 32b of the conductor pattern 32a, which surround the antenna 2 in each of the first conductor layer 31 and the second conductor layer 32, do not have to overlap in a plan view. In the example of FIG. 4, the inner edge 31b of the conductor pattern 31a defines the boundary between the peripheral region P and the antenna region A. As described above, when the inner edges of the conductor patterns 31a and 32a do not overlap in a plan view, the antenna region A is defined by the inner edge of each of the conductor patterns 31a and 32a farther from the antenna 2.

Further, in the example of FIG. 4, the inner edge 31b of the conductor pattern 31a draws the circumference of an ellipse. Therefore, the antenna region A has an elliptical shape in a plan view. As described above, the planar shape of the antenna region A is not limited to a rectangle, and the antenna region A can have an arbitrary planar shape. Similarly, the inner edge 32b of the conductor pattern 32a can also outline any shape. Further, unlike the example of FIG. 4, the inner edge 32b of the conductor pattern 32a may be located outside the inner edge 31b of the conductor pattern 31a in a plan view.

FIG. 5 shows a cross-sectional view of the wiring board 1a, which is another example of the wiring board of the present embodiment. The wiring board 1a illustrated in FIG. 5 has the same structure as the wiring board 1 of FIG. 1, and in the first conductor layer 31 and the second conductor layer 32, the first interval L1 is the second interval L2. Shorter than. However, in the wiring board 1a, the upper surface of the first insulating layer 41 and the upper surfaces of the three interlayer insulating layers 4a are not curved toward the core substrate 10 even in the antenna region A, and most of them are flat. The step due to the conductor layer 3c on the core substrate 10 is substantially absorbed by the first insulating layer 41, and the step due to the first conductor layer 31 on the first insulating layer 41 is substantially absorbed by the interlayer insulating layer 4a above the first insulating layer 41. There is. On the other hand, on the upper two surfaces of the three interlayer insulating layers 4a, at the boundary portion between the antenna region A and the peripheral region P, a step corresponding to the thickness of one or two conductor layers 3a is provided. Is occurring. Each insulating layer having a flat surface in the antenna region A is formed as in the example of FIG. 5 depending on the viscosity and fluidity of the resin material before curing when the first insulating layer 41 and the three interlayer insulating layers 4a are formed. Can be done.

Next, an example of the manufacturing method of the wiring board 1 shown in FIG. 1 will be described with reference to FIGS. 6A to 6E.

As shown in FIG. 6A, a laminated board having an insulating layer 40 constituting the core substrate 10 and metal foils 3e provided on both sides of the insulating layer 40 is prepared. For example, a double-sided copper-clad laminate having a metal foil 3e made of copper is prepared.

As shown in FIG. 6B, the through hole 10b is formed by irradiation with carbon dioxide laser light or the like, and includes, for example, a copper foil, a copper electroless plating film, and an electroplating film by using a semi-additive method. Conductor layers 3c and 3d having a desired conductor pattern are formed. Further, the through-hole conductor 10a is formed by embedding the electroless plating film and the electrolytic plating film in the through holes 10b.

As shown in FIG. 6C, the first and second insulating layers 41 and 42 are formed. Further, the first conductor layer 31 including the first radiating element 21 is formed on the first insulating layer 41. Along with the formation of the first conductor layer 31, the third conductor layer 33 including the signal transmission line 331 is formed on the second insulating layer 42. In the formation of the first conductor layer 31, one or more via conductors 5a including the first via conductor 51 are formed in the first insulating layer 41. Further, in the formation of the third conductor layer 33, one or more via conductors 5b including the second via conductor 52 are formed in the second insulating layer 42.

For the first and second insulating layers 41 and 42, for example, a prepreg containing a semi-cured epoxy resin and a reinforcing material such as glass fiber, or a film-shaped epoxy resin is laminated on both sides of the core substrate 10 to heat the core substrate 10. It is formed by crimping. Since the conductor layer 3c does not have a conductor pattern in the antenna region A, the first insulating layer 41 is formed so as to have a curved surface. When laminating the prepreg, a metal foil made of, for example, copper may be laminated on the prepreg and crimped together with the prepreg. After that, for example, by irradiating carbon dioxide laser light, through holes 5a1 and 5b1 for forming the via conductors 5a and 5b are formed in the first and second insulating layers 41 and 42, respectively.

Then, for example, using the semi-additive method, the first and third conductor layers 31, 33, and the first and second vias having a desired conductor pattern such as the first radiation element 21 and the signal transmission line 331 are used. Via conductors 5a and 5b such as conductors 51 and 52 are formed.

In the formation of the first conductor layer 31, a recess 21b is provided on the upper surface of the first radiating element 21 (a surface facing the direction opposite to the first insulating layer 41). The recess 21b is provided on the first via conductor 51. The recess 21b can be formed, for example, by optimizing the electroplating conditions in the formation of the first via conductor 51. For example, the dent 21b is formed by reducing the content of a brightener or the like that contributes to an increase in the amount of current in a hole such as a through hole 5a1 as compared with an additive applied to a plating solution when forming a general filled via. It can be provided intentionally.

As shown in FIG. 6D, three interlayer insulating layers 4a are formed on the first conductor layer 31. A via conductor 5a is formed in each of the three interlayer insulating layers 4a. Further, a conductor layer 3a is formed between each of the three interlayer insulating layers 4a. Each of the two conductor layers 3a is formed and / or patterned so as not to have a conductor pattern in the antenna region A. In the example of FIG. 6D, the metal foil 32c that should form a part of the second conductor layer 32 is further laminated on the interlayer insulating layer 4a of the uppermost layer of the three interlayer insulating layers 4a. Since the first conductor layer 31 and the two conductor layers 3a do not have a conductor pattern in the antenna region A, the three interlayer insulating layers 4a are formed so as to have curved surfaces, respectively. The metal foil 32c is also curved along the surface of the interlayer insulating layer 4a. The three interlayer insulating layers 4a and the two conductor layers 3a can be formed, for example, by using a general method for manufacturing a build-up wiring board using a semi-additive method.

On the third conductor layer 33, the three interlayer insulating layers 4a, the two conductor layers 3a, and the via conductor 5a are formed in the same manner as the three interlayer insulating layers 4a, and the two conductor layers 3b. The via conductor 5b is formed. A metal foil 3b2 that should form the outermost conductor layer 3b is laminated on the uppermost interlayer insulating layer 4b.

Then, for example, by forming a plating film on each of the metal foils 32c and 3b2 using a semi-additive method, a second conductor layer 32 is formed as shown in FIG. 6E, and three interlayer insulating layers 4b are formed. The outermost conductor layer 3b is formed on the surface. The second conductor layer 32 is formed and / or patterned so as to include the second radiating element 22 constituting the antenna 2 together with the first radiating element 21. The outermost conductor layer 3b is formed and / or patterned so as to include the connection pad 3b1. As a result of the formation of the conductor layer and the insulating layer, the first build-up layer 11 and the second build-up layer 12 are formed.

After that, the solder resist layer 6a is formed on the first build-up layer 11, and the solder resist layer 6b is formed on the second build-up layer 12. The solder resist layers 6a and 6b are formed by, for example, forming a resin layer containing a photosensitive epoxy resin, a polyimide resin, or the like, exposure using a mask having an appropriate pattern, and development.

The connection pad 3b1 exposed to the opening of the solder resist layer 6b is subjected to electroless plating, solder leveler, spray coating or the like, if necessary, to Au, Ni / Au, Ni / Pd / Au, solder, or heat resistance. A surface protective film (not shown) made of preflux or the like may be formed. By going through the above steps, the wiring board 1 of the example of FIG. 1 is completed.

The wiring board of the embodiment is not limited to the structure exemplified in each drawing and the structure, shape, and material exemplified in this specification. For example, the recess 21b on the surface 21a of the first radiation element 21 may not be provided, and the recess 21b may be provided in the central portion of the first radiation element 21 in a plan view. The first and second radiating elements 21, 22 and the signal transmission line 331 may all be formed on one of the first build-up layer 11 and the second build-up layer 12. Further, each via conductor such as the first via conductor 51 does not have to have a shape of reducing the diameter toward the core substrate 10 side. The second radiating element 22 may be exposed to the opening of the solder resist layer 6a, or the solder resist layers 6a and 6b themselves may not be provided. Further, the wiring board 1 does not necessarily have to have the core board 10, and may be a coreless build-up board composed of only the build-up layer.

1, 1a Wiring board 10 Core board 11 1st build-up layer 12 2nd build-up layer 2 Antenna 21 1st radiating element 22 2nd radiating element 31 1st conductor layer 32 2nd conductor layer 32a Conductor pattern 331 Signal transmission path 4a 4b Interlayer insulation layer 51 1st via conductor 6a, 6b Solder resist layer A Antenna region L1 1st distance between 1st conductor layer and 2nd conductor layer L2 2nd distance MD between 1st conductor layer and 2nd conductor layer Distance corresponding to creepage distance SD in plan view P Peripheral region SD Crawl distance along the surface of the interlayer insulating layer between the second radiating element and the conductor pattern

Claims (7)

The first conductor layer including the first radiating element constituting the antenna,
A second conductor layer including the second radiating element constituting the antenna together with the first radiating element,
Two or more interlayer insulating layers interposed between the first conductor layer and the second conductor layer,
It is a wiring board equipped with
The wiring board has an antenna region including the antenna and a peripheral region which is a peripheral region of the antenna region in a plan view.
The first conductor layer and the second conductor layer have a first spacing in the antenna region and a second spacing in the peripheral region between each other.
The first interval is shorter than the second interval. In the wiring board according to claim 1, the first radiating element and the second radiating element face each other in the antenna region via the two or more interlayer insulating layers. The wiring board according to claim 1, further comprising a solder resist layer covering the second conductor layer.
The thickness of the solder resist layer in the antenna region is thicker than the thickness of the solder resist layer in the peripheral region. The wiring board according to claim 1, wherein the second radiating element is curved so as to be convex toward the first radiating element. The wiring board according to claim 1.
The second radiating element has conductivity and
The second conductor layer further includes a conductor pattern formed around the second radiating element.
The creepage distance between the second radiation element and the conductor pattern along the surface of the two or more interlayer insulating layers is longer than the distance corresponding to the creepage distance in a plan view. The wiring board according to claim 1, wherein the first radiation element is a power feeding element to which a transmission / reception signal in the antenna should be transmitted, and the second radiation element is insulated from a conductor other than the second radiation element. It is a non-feeding element. The wiring board according to claim 6, wherein the wiring board has a structure including two build-up layers including the same number of conductor layers and a core board sandwiched between the two build-up layers. Ori,
The first radiating element is contained in one of the two build-up layers.
The other of the two build-up layers includes a signal transmission line that transmits the transmission / reception signal.

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