TW201413901A - Antenna substrate - Google Patents

Abstract

An antenna substrate of the present invention is provided with a ground conductor 3 on one main surface of a core insulating plate 1 having a through hole 2, and alternately laminated with a built-up insulating layer 4 and a built-up wiring layer 6 having a thickness thinner than the core insulating plate on the one main surface containing the ground conductor 3, an antenna pad 7 is provided at a position opposed to the ground conductor 3 on the other main surface of the core insulating plate 1, and the antenna pad 7 is electrically connected to the built-up wiring layer 6 through the through hole 2.

Description

Antenna substrate

The present invention relates to an antenna substrate in which an antenna pad and a grounding conductor are provided opposite to each other in a multilayer wiring board.

Conventionally, an antenna substrate 30 is known as an antenna substrate. As shown in FIG. 3, the antenna substrate 30 is provided with an antenna pad 27 on one side of a main surface of a multilayer wiring substrate, and an antenna The semiconductor element S is mounted on the other main surface side in such a manner that the pad 27 is electrically connected. The antenna substrate 30 is formed on both main faces of the core insulating sheet 21 having the through holes 22, and a plurality of layers of the build-up insulating layer 24 having the via holes 25 and the build-up wiring layer 26 are alternately laminated. The antenna pad 27 is formed by the build-up wiring layer 26, and is provided on the outermost layer of the build-up insulating layer 24 on one of the main surface sides. Further, the grounding conductor 23 is disposed on the main surface of the core insulating sheet 21 on the main surface side of the one surface so as to face the antenna pad 27. The grounding conductor 23 is a reflection conductor for reflecting the electric wave emitted from the antenna pad 27, whereby the radio wave emitted from the antenna pad 27 is efficiently directed from the main surface side of the antenna substrate 30. External launch. Further, the antenna pad 27 and the grounding conductor 23 are opposed to each other by sandwiching a plurality of build-up insulating layers 24, whereby the antenna pad 27 and the grounding conductor 23 can be used. Ensure proper spacing. When the distance between the antenna pad 27 and the ground conductor 23 is too narrow, a large power storage body is formed between the two, which becomes an obstacle to radio wave emission.

A plurality of semiconductor element connection pads 29 formed by the buildup wiring layer 26 and connected to the semiconductor element S are formed on the outermost layer of the buildup insulating layer 24 on the other main surface side of the antenna substrate 30. Further, one of the semiconductor element connection pads 29 and the antenna pad 27 are electrically connected via the communication hole 25 and the through hole 22 which are formed to overlap each other. A through-hole conductor 22a is formed in the through hole 22, and a communication conductor 25a is formed in the communication hole 25. Further, a via land 25b is formed between the communication conductors 25a which are vertically overlapped with each other. The communication pad 25b is formed integrally with the communication conductor 25a and has a diameter slightly larger than the diameter of the communication hole 25. In this manner, by making the diameter of the communication pad 25b slightly larger than the diameter of the communication hole 25, even when the positions of the communication holes 25 located at the upper and lower sides are slightly shifted from each other, the communication holes 25 can be reliably connected. between. Further, through hole pads 22b are formed at both ends of the through hole conductor 22a. The through hole pad 22b is formed integrally with the through hole conductor 22a, and its diameter is slightly larger than the diameter of the through hole 22. As described above, by making the diameter of the through hole pad 22b slightly larger than the diameter of the through hole 22, even when the through hole 22 and the position of the upper and lower communication holes 25 are slightly shifted from each other, the connection can be surely connected. The through hole 22 and the communication hole 25 are provided. Further, a solder resist layer 28 is coated on the outermost surfaces of both main surfaces of the antenna substrate 30. The solder resist layer 28 has a portion for exposing a portion of the build-up wiring layer 26 as a semiconductor element. The opening portion 28a of the pad 29 is covered with the remaining portion of the build-up wiring layer 26.

Further, in the antenna substrate 30, a high frequency signal is supplied from the semiconductor element S to the antenna pad 27 via the through hole 22 and the communication hole 25, whereby a high frequency signal is emitted from the antenna pad 27 as a radio wave.

Further, such an antenna substrate 30 is incorporated in a communication device and used for, for example, the purpose of transmitting to a communication device located at a place away from a high-frequency signal such as a sound or a video. For example, JP-A-5-183328 discloses a microwave circuit for use in a mobile station wireless communication terminal of a mobile wireless communication system such as a road-to-vehicle communication system. In recent years, these communication devices have been required to be able to transmit and receive signals in a wider range. In order to cope with this requirement, high frequency signals must be transmitted with higher output.

However, as the high output progresses, a part of the radio wave emitted from the antenna pad 30 in the inner direction of the antenna substrate 30 becomes a portion interposed between the connection antenna pad 27 and the through hole pad 22b. The position of the communication pad 25b between the communicating conductors 25a is received by the communication pad 25b closer to the antenna pad 27 than the grounding conductor 23. As a result, a part of the radio wave received by the communication pad 25b mixes with the radio wave emitted from the antenna pad 27 as noise, and there is a case where a high frequency signal such as sound or video cannot be normally transmitted.

The subject of the present invention is to provide a reduction and The noise mixed by the radio wave emitted by the antenna pad is an antenna substrate capable of transmitting a high frequency signal normally.

In the antenna substrate of the present invention, a grounding conductor is provided on one main surface of the core insulating sheet having the through hole, and the thickness of the laminated main layer on the one main surface including the grounding conductor is thinner than that of the core insulating sheet. The layer insulating layer and the build-up wiring layer are provided with an antenna pad at a position facing the grounding conductor on the other main surface of the core insulating plate, and the antenna pad is connected to the build-up via the through hole The wiring layer is electrically connected.

In the antenna substrate of the present invention, a grounding conductor is provided on one main surface of the core insulating sheet having the through hole, and an antenna pad facing the grounding conductor is formed on the other main surface of the core insulating sheet. That is, the antenna pads are opposed to the grounding conductor system sandwiching the core insulating sheets. The core insulating plate does not have to be provided with a solder pad in the middle of the through-hole conductor even if its thickness is thick. Therefore, it is not necessary to provide an unnecessary pad at the side closer to the antenna pad than the grounding conductor, and it is possible to ensure a sufficient space between the antenna pad and the grounding conductor. Therefore, it is possible to provide an antenna substrate capable of preventing noise generated by the pad from being mixed into the radio wave emitted from the antenna pad and capable of normally transmitting a high frequency signal such as a sound or a video.

1, 11, 21‧ ‧ core insulation board

2, 22‧‧‧through holes

2a, 22a‧‧‧through hole conductor

2b, 22b‧‧‧through hole pads

3, 13, 23‧‧‧ Grounding conductor

4,14,24‧‧‧Additional insulation

5, 25‧‧‧Connected holes

5a‧‧‧Connected conductor

5b, 25b‧‧‧Connecting pads

6, 26‧‧‧Addition wiring layer

7, 17, 27‧‧‧ Antenna pads

8, 28‧‧‧ solder resist layer

8a‧‧‧ openings

9, 29‧‧‧Semiconductor component connection pads

10, 20, 30‧‧‧ antenna substrate

11a, 11b, 11c‧‧‧ insulation

18‧‧‧core wiring layer

28a‧‧‧ openings

S‧‧‧Semiconductor components

T‧‧‧ electrodes

Fig. 1 is a schematic cross-sectional view showing an antenna substrate according to an embodiment of the present invention; Surface map.

Fig. 2 is a schematic cross-sectional view showing another embodiment of the antenna substrate of the present invention.

Fig. 3 is a schematic cross-sectional view showing a conventional antenna substrate.

Next, an embodiment of an antenna substrate of the present invention will be described based on Fig. 1 . As shown in Fig. 1, the antenna substrate 10 of the present invention alternately laminates the build-up insulating layer 4 having the communication holes 5 and the build-up wiring layer only on the main surface side of one of the core insulating sheets 1 having the through holes 2. Formed by 6. On the outermost layer of the buildup insulating layer 4 on the one main surface side, a semiconductor element connection pad 9 formed of the buildup wiring layer 6 and connected to the electrode T of the semiconductor element S is formed. The grounding conductor 3 is disposed on one of the main surfaces of the core insulating plate 1, and the antenna pad 7 is formed on the other main surface of the core insulating plate 1 so as to face the grounding conductor 3. . Further, one of the antenna pads 7 and the semiconductor element connection pads 9 (the communication pads 5b) is electrically connected to each other via the through holes 2 and the communication holes 5 which are formed to overlap each other. Further, the solder resist layer 8 is coated on the outermost surface of the both main faces.

A through-hole conductor 2a is formed in the through hole 2 described above, and a communication conductor 5a is formed in the communication hole 5. A communication pad 5b is formed between the communication conductors 5a that overlap each other. Through-hole pads 2b are formed at both ends of the through-hole conductor 2a. Further, the semiconductor element connection pad 9 (including the communication pad 5b of the build-up insulating layer 4 formed on the outermost layer) and the electrode T of the semiconductor element S are electrically connected via solder bumps. From half The conductor element S supplies a high frequency signal to the antenna pad 7 via the communication hole 5 and the through hole 2, thereby transmitting a high frequency signal from the antenna pad 7 as an electric wave.

The core insulating sheet 1 is made of, for example, an electrically insulating material in which a thermosetting resin such as an epoxy resin or a bismaleimide-triazine resin is impregnated into a glass fiber cloth. The thickness of the core insulating sheet 1 is equal to or greater than the thickness of the buildup insulating layer 4 to be described later. The antenna pad 7 and the ground conductor 3 must be provided at a certain interval to suppress a capacitance component (an electric storage body) formed therebetween. Therefore, the core insulating sheet 1 must have a certain thickness. Further, by setting the thickness of the core insulating sheet 1 to be equal to or greater than the thickness of the buildup insulating layer 4, it is not necessary to sandwich the antenna pad 7 and the ground conductor 3 with the buildup insulating layer. As a result, the communication pads provided in the sandwiched insulating layer do not receive radio waves, and noise can be reduced.

The thickness of the core insulating sheet 1 is preferably about 150 to 400 μm. When the ratio is less than 150 μm, there is a possibility that an electric storage body is formed between the antenna pad 7 and the grounding conductor 3, and there is a problem that the electric wave is normally emitted from the antenna pad 7. In addition, when it is larger than 400 μm, it is necessary to enlarge the opening diameter of the through hole 2 to form the through-hole conductor 2a, which may hinder the high-density wiring.

The through hole 2 has an opening diameter of about 100 to 150 μm and is formed, for example, by drilling. When the opening diameter of the through hole is excessively large, the high density wiring may be hindered as described above. The through-hole conductor 2a is formed of a copper-plated layer, and is formed by coating a copper plating layer on the inner wall of the through-hole by, for example, electroless copper plating, and then performing copper plating by electrolytic copper plating.

The through-hole pad 2b, the grounding conductor 3, and the antenna pad 7 are mainly formed by a plating method using a metal such as copper, and are preferably, for example, about 5 to 25 μm by a known semi-additive method. The thickness is formed.

The antenna pad 7 functions as an antenna that emits a high-frequency signal supplied from the semiconductor element S as a radio wave. The antenna pad 7 is a circular or square or polygonal shape having a predetermined area, and when the size is, for example, a square shape, it is preferably about 0.3 to 1.5 μm on one side.

The grounding conductor 3 is a pattern that faces the antenna pad 7 in a planar shape, and serves as a reflecting plate that reflects the radio wave emitted from the antenna pad 7 toward the inside of the antenna substrate 10 and reflects it to the outside. Features.

At this time, the antenna pad 7 and the grounding conductor 3 are opposed to each other with the core insulating sheet 1 having a thickness of about 150 to 400 μm. The core insulating sheet 1 does not have to be provided with a pad in the middle of the through-hole conductor 2a even when the thickness thereof is made thicker by about 150 to 400 μm. Therefore, it is possible to ensure a sufficient space between the antenna pad 7 and the grounding conductor 3 without interposing an unnecessary pad on the side closer to the antenna pad 7 than the grounding conductor 3.

The buildup insulating layer 4 is obtained by thermally curing an electrical insulating material containing a thermosetting resin such as an epoxy resin or a polyimide resin. The buildup insulating layer 4 is formed to be thinner than the core insulating sheet 1. When the build-up insulating layer 4 is too thick, the aspect ratio of the communication hole 5 is high when the communication hole 5 is reduced, and it is difficult to fill the inside of the communication hole 5 by the communication conductor 5a. The thickness of the buildup insulating layer 4 is preferably from 30 to 70 μm per layer. In addition, the communication hole 5 is Formed by laser processing. A part of the conductor constituting the build-up wiring layer 6 such as the communication pad 5b is filled in the communication hole 5 as the communication conductor 5a, whereby conduction of the build-up wiring layer is performed.

The buildup wiring layer 6 is mainly formed of a wiring formed of a metal such as copper by a plating method, and is formed by, for example, a known semi-additive method, and is supplied between the semiconductor element S and the antenna pad 7 as a power supply. Or function as a signal path. When the buildup insulating layer 4 and the buildup wiring layer 6 are alternately laminated, the buildup wiring layer 6 is laminated on the outermost layer. The semiconductor element connection pad 9 and the communication pad 5b are formed by a part of the buildup wiring layer 6. The thickness of the build-up wiring layer 6 is preferably about 10 to 25 μm per layer.

The buildup insulating layer 4 and the buildup wiring layer 6 are only coated on the main surface of the core insulating sheet 1 on which the ground conductor 3 is formed. Therefore, when the build-up insulating layer 4 is thermally hardened, for example, heat shrinkage occurs and warpage occurs in the antenna substrate 10 during processing. To avoid this, a plurality of build-up wiring layers are sequentially formed. At the same time, the plating is also deposited as the upper surface of the metal of the antenna pad 7, and the thickness of the metal is increased. Thereby, rigidity can be imparted to the other main surface side where the buildup insulating layer 4 and the buildup wiring layer 6 are not formed, and warpage of the antenna substrate 10 due to thermal contraction of the buildup insulating layer 4 can be suppressed. Further, after the formation of all the buildup wiring layers 6 is completed, the plating of the upper surface of the metal as the antenna pad 7 may be thinned to a predetermined thickness by etching, polishing, or the like.

The buildup insulating layer 4 and the buildup wiring layer 6 are preferably alternately laminated in two or three layers. By setting the number of layers as described above, it is possible to further The warpage of the antenna substrate 10 due to thermal contraction of the buildup insulating layer 4 is suppressed.

The solder resist layer 8 is made of an electrically insulating material obtained by curing a thermosetting resin such as an acrylic modified epoxy resin. The solder resist layer 8 has an opening portion 8a which exposes a part of the build-up wiring layer 6 as a semiconductor element connection pad 9, and covers the remaining portion of the build-up wiring layer 6. Thereby, the electrode T of the semiconductor element S can be connected to the semiconductor element connection pad 9, and the remaining portion of the build-up wiring layer 6 can be protected from the external environment.

As described above, in the antenna substrate 10 of the present invention, the grounding conductor 3 is formed on one main surface of the core insulating sheet 1, and the antenna pad is formed on the other main surface of the core insulating sheet 1 facing the grounding conductor 3. 7, it is possible to ensure a sufficient space between the grounding conductor 3 and the antenna pad 7, without having to place an unnecessary pad on the side closer to the antenna pad 7 than the grounding conductor 3. Therefore, it is possible to provide the antenna substrate 10 capable of preventing the noise caused by the pad from being mixed into the radio wave emitted from the antenna pad 7, and capable of transmitting a high-frequency signal such as a sound or an image normally.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit and scope of the invention.

In the above embodiment, the core insulating sheet 1 has a single layer structure. However, as shown in Fig. 2, a plurality of layers in which a plurality of insulating layers 11a, 11b, and 11c made of the same or different electrically insulating materials are laminated in a plurality of layers may be used. By making this multilayer structure, The core wiring layer 18 is formed, for example, in a region of the core insulating plate 11 surrounded by the grounding conductor 13 and the antenna pad 17. Further, the core wiring layer 18 is a wiring layer formed inside the core insulating sheet 11 (for example, between the insulating layers 11a and 11b and between the insulating layers 11b and 11c), and is different from the build-up wiring layer. Thereby, it is possible to provide the antenna substrate 20 capable of forming a high-density wiring without increasing the number of layers of the build-up insulating layer 14, and having high rigidity of the core insulating sheet 11.

Further, in the above embodiment, the antenna pad 7 is directly formed on the other main surface of the core insulating sheet 1. However, as shown in Fig. 2, the antenna pad 17 can also be formed on the build-up insulating layer 14 which is laminated on the other main surface of the core insulating sheet 11. By laminating one layer of the insulating layer 14 on the upper side of the core insulating sheet 11, it is possible to alleviate the expansion and contraction of the build-up insulating layer 14 which is laminated on the lower surface of the core insulating sheet 11 due to the thermal history during manufacture. Warp. Therefore, the antenna substrate 20 with small warpage can be provided.

1‧‧‧core insulation board

2‧‧‧through holes

2a‧‧‧through hole conductor

2b‧‧‧through hole pads

3‧‧‧ Grounding conductor

4‧‧‧Additional insulation

5‧‧‧Connected holes

5a‧‧‧Connected conductor

5b‧‧‧Connecting pads

6‧‧‧Additional wiring layer

7‧‧‧Antenna pads

8‧‧‧ solder resist layer

8a‧‧‧ openings

9‧‧‧Semiconductor component connection pads

10‧‧‧Antenna substrate

S‧‧‧Semiconductor components

T‧‧‧ electrodes

Claims (6)

An antenna substrate in which a grounding conductor is provided on one main surface of a core insulating plate having a through hole, and a buildup layer having a thickness thinner than the core insulating plate is alternately laminated on the one main surface including the grounding conductor An insulating layer and a build-up wiring layer; and an antenna pad provided at a position facing the grounding conductor on the other main surface of the core insulating plate, wherein the antenna pad passes through the through hole and the build-up wiring Layer electrical connection. The antenna substrate according to claim 1, wherein the core insulating plate has a thickness of 150 to 400 μm, and the build-up insulating layer has a thickness of 30 to 70 μm. The antenna substrate according to claim 1 or 2, wherein the through hole has an opening diameter of 100 to 150 μm. The antenna substrate according to claim 1 or 2, wherein the buildup insulating layer and the buildup wiring layer are alternately laminated in two or three layers. The antenna substrate according to claim 1 or 2, wherein the other main layer of the core insulating sheet is provided with an insulating layer, and the antenna pad is provided on the build-up insulating layer. The antenna substrate according to claim 1 or 2, wherein the core insulating plate is formed of a plurality of insulating layers.