# US 12,193,151 B2 · High-frequency circuit board and antenna module

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- Number: US 12,193,151 B2
- Document ID: US12193151B2
- Status: Granted
- Kind: B2
- Application number: 18/157,489
- Filed: 2023-01-20
- Published: 2023-11-02
- Granted: 2025-01-07
- Earliest claimed: 2022-03-30
- Assignees: Fujitsu Limited
- Applicants: Fujitsu Limited
- Inventors: Shirou Ozaki; Naoya Okamoto; Yoshihiro Nakata; Yusuke Kumazaki; Toshihiro Ohki; Naoki Hara
- Web page: https://patentgrep.com/patent/US12193151B2

## CPC

- H01Q 1/1207: {for fastening a rigid aerial element}
- H05K 1/0243: {Printed circuits associated with mounted high frequency components}
- H01Q 1/12: Supports; Mounting means
- H05K 1/115: {Via connections; Lands around holes or via connections (H05K1/112 takes precedence)}
- H01Q 1/2283: {mounted in or on the surface of a semiconductor substrate as a chip-type antenna or integrated with other components into an IC package}
- H05K 2201/10098: Components for radio transmission, e.g. radio frequency identification [RFID] tag, printed or non-printed antennas
- H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72)
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS

## Abstract

A high-frequency circuit board includes: a first insulating layer having a first dielectric constant; a first metal layer provided to stack over the first insulating layer; a second insulating layer provided to stack over the first metal layer, and having a second dielectric constant lower than the first dielectric constant; a second metal layer provided to stack over the second insulating layer, on which a compound semiconductor device is mounted; and first vias penetrating the second insulating layer and connecting the first metal layer with the second metal layer.

## Claims

### Claim 1

A high-frequency circuit board comprising: a first insulating layer having a first dielectric constant; a first metal layer provided to stack over the first insulating layer; a second insulating layer provided to stack over the first metal layer, and having a second dielectric constant lower than the first dielectric constant; a second metal layer provided to stack over the second insulating layer, on which a compound semiconductor device is mounted; and first vias penetrating the second insulating layer and connecting the first metal layer with the second metal layer, further comprising: a third metal layer arranged on an opposite side to the first metal layer with respect to the first insulating layer, and held at reference potential; and second vias penetrating the first insulating layer and connecting the first metal layer with the third metal layer.

### Claim 2 (depends on 1)

The high-frequency circuit board as claimed in claim 1, wherein the first metal layer and the third metal layer are formed in part of a region where the first insulating layer is present in plan view.

### Claim 3 (depends on 1)

The high-frequency circuit board as claimed in claim 1, wherein the second insulating layer is a resin layer or a quartz layer.

### Claim 4 (depends on 1)

The high-frequency circuit board as claimed in claim 1, wherein a thickness of the second insulating layer is less than ¼ of a wavelength at a frequency of a signal at which the compound semiconductor device processes the signal.

### Claim 5 (depends on 1)

The high-frequency circuit board as claimed in claim 1, wherein the second insulating layer is made of SiC, AlN, or Si.

### Claim 6 (depends on 1)

The high-frequency circuit board as claimed in claim 1, wherein a thickness of the first insulating layer is greater than or equal to ¼ of a wavelength at a frequency of a signal input into the compound semiconductor device.

### Claim 7 (depends on 1)

The high-frequency circuit board as claimed in claim 1, wherein the first insulating layer has a thickness of greater than or equal to 100 μm.

### Claim 8 (depends on 1)

The high-frequency circuit board as claimed in claim 1, wherein an interval between the first vias is less than or equal to 100 μm.

### Claim 9

An antenna module comprising:
an antenna; and
a high-frequency circuit board on which the antenna is mounted,
wherein the high-frequency circuit board includes:
a first insulating layer having a first dielectric constant,
a first metal layer provided to stack over the first insulating layer,
a second insulating layer provided to stack over the first metal layer, and having a second permittivity lower than a first permittivity,
a second metal layer provided to stack over the second insulating layer, on which a compound semiconductor device is mounted, and
first vias penetrating the second insulating layer and connecting the first metal layer with the second metal layer.