High-frequency circuit board and antenna module
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.
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.
2. 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.
3. The high-frequency circuit board as claimed in claim 1 , wherein the second insulating layer is a resin layer or a quartz layer.
4. 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.
5. The high-frequency circuit board as claimed in claim 1 , wherein the second insulating layer is made of SiC, AlN, or Si.
6. 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.
7. 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.
8. 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.
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.