US-20260129744-A1 - SUBSTRATE CONNECTION STRUCTURE, AND ANTENNA DEVICE AND COMMUNICATION DEVICE INCORPORATING SAME

Abstract

An opposing surface of a first substrate faces a side surface of a second substrate. The first substrate includes a first signal line, a first signal electrode, and a first ground electrode. The first ground electrode has an opening that surrounds the first signal electrode. The second substrate includes a second signal electrode, a second signal line, and a second ground electrode. The second ground electrode includes a first portion that overlaps the second signal electrode and a second portion that does not overlap the second signal electrode when viewed in an X-axis direction. A distance in the X-axis direction between the second signal electrode and the first portion is greater than a distance in the X-axis direction between the second signal line and the second portion.

Inventors

• Yosuke Sato

Assignees

• MURATA MANUFACTURING CO., LTD.

Dates

Publication Date

20260507

Application Date

20251222

Priority Date

20230919

Claims (19)

1. 1 . A substrate connection structure comprising: a first substrate; and a second substrate having a main surface and a side surface that intersect each other, wherein the first substrate includes an opposing surface facing the side surface of the second substrate, a first signal line disposed opposite the opposing surface, a plate-shaped first ground electrode that is disposed on the opposing surface or that is disposed opposite the opposing surface at a position between the opposing surface and the first signal line, and a first signal electrode connected to the first signal line and exposed on the opposing surface, the second substrate includes a second signal line disposed opposite the main surface, a plate-shaped second ground electrode disposed opposite the main surface at a position between the main surface and the second signal line, and a second signal electrode connected to the second signal line, and exposed on the side surface and connected to the first signal electrode, the first ground electrode is configured to sandwich the first signal electrode from at least two directions when viewed in a first direction that is a normal direction of the opposing surface, the second ground electrode includes a first portion connected to the first ground electrode, and a second portion connected to the first portion, when viewed in a second direction that is a normal direction of the main surface, at least part of the first portion overlaps the second signal electrode, and the second portion does not overlap the second signal electrode, and a distance in the second direction between the second signal electrode and the first portion is greater than a distance in the second direction between the second signal line and the second portion.
2. 2 . The substrate connection structure according to claim 1 , wherein a size of the second signal electrode in the second direction is larger than a size of the second signal line in the second direction.
3. 3 . The substrate connection structure according to claim 1 , wherein the second ground electrode further includes a connection conductor extending in the second direction and connecting the first portion to the second portion, and a third portion extending in the first direction from a connection portion between the connection conductor and the second portion, and a distance in the first direction between the connection conductor and the second signal electrode is greater than a size of the connection conductor in the first direction.
4. 4 . The substrate connection structure according to claim 1 , wherein the second signal electrode has a rectangular parallelepiped shape or a semi-cylindrical shape.
5. 5 . The substrate connection structure according to claim 1 , wherein the first ground electrode has an opening that opens so as to surround the first signal electrode when viewed in the first direction, and when a shortest distance between the first signal electrode and an inner wall of the opening in an extension direction of the first signal line is defined as a first distance, a distance between the second signal electrode and the first portion in the second direction is defined as a second distance, and a distance between the first signal electrode and the inner wall of the opening in a direction perpendicular to the first direction and the extension direction of the first signal line is defined as a third distance, the third distance is greater than half the second distance, greater than the first distance, and less than twice the second distance.
6. 6 . The substrate connection structure according to claim 1 , wherein the first ground electrode has an opening that opens so as to surround the first signal electrode when viewed in the first direction, and further includes a specific portion extending in the first direction from an inner wall of the opening toward an imaginary line at a position where the imaginary line overlaps the inner wall of the opening when viewed in the first direction when the imaginary line is drawn from the first signal line in an extension direction of the first signal line, and a distance in the second direction between the first signal electrode and the specific portion is substantially equal to a distance in the second direction between the second signal electrode and the first portion.
7. 7 . The substrate connection structure according to claim 1 , wherein the first ground electrode has an opening that opens so as to surround the first signal electrode when viewed in the first direction, and a plurality of a combination of the first signal line, the first signal electrode, and the opening are disposed side by side along the opposing surface of the first substrate.
8. 8 . The substrate connection structure according to claim 1 , wherein the first signal electrode is connected to the second signal electrode via a first solder bump, and the first ground electrode is connected to the first portion of the second ground electrode via a second solder bump.
9. 9 . The substrate connection structure according to claim 1 , wherein the first ground electrode is disposed on the opposing surface of the first substrate.
10. 10 . The substrate connection structure according to claim 1 , wherein the second ground electrode further includes a connection conductor connecting the first portion to the second portion.
11. 11 . The substrate connection structure according to claim 1 , wherein the first signal electrode includes a first pad connected to the first signal line, a second pad exposed on the opposing surface, and a connection conductor connecting the first pad and the second pad.
12. 12 . The substrate connection structure according to claim 1 , wherein the first ground electrode is configured to sandwich the first signal electrode from three directions when viewed in the first direction.
13. 13 . The substrate connection structure according to claim 12 , wherein the first ground electrode is configured to sandwich the first signal electrode from four directions when viewed in the first direction.
14. 14 . The substrate connection structure according to claim 1 , wherein the first substrate and the second substrate are formed of different dielectric materials.
15. 15 . An antenna device comprising: the substrate connection structure according to claim
16. 1 .
17. 16 . The antenna device according to claim 15 , further comprising: a plurality of radiating elements disposed on the main surface of the second substrate, wherein the first signal line and the second signal line form part of a feed wiring configured to supply a signal to at least one of the plurality of radiating elements.
18. 17 . A communication device comprising: the substrate connection structure according to claim 1 .
19. 18 . The communication device according to claim 17 , further comprising a radio frequency integrated circuit (RFIC) mounted on the first substrate, wherein the first signal line is configured to electrically couple the RFIC to the first signal electrode.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of International Application No. PCT/JP2024/020922, filed on Jun. 7, 2024, which claims priority to Japanese Patent Application No. 2023-150980, filed on Sep. 19, 2023. The entire disclosures of the prior applications are hereby incorporated by reference in their entirety. TECHNICAL FIELD The present disclosure relates to a substrate connection structure, and an antenna device and a communication device incorporating the same. BACKGROUND ART International Publication No. 2020/170722 (Patent Document 1) discloses an antenna device including flat patch antennas (radiating elements). In this antenna device, the patch antenna are disposed in a substrate connection structure formed by connecting a first substrate and a second substrate having different normal directions from each other. The first substrate and the second substrate are connected to each other via a bent portion, and a ground electrode for the patch antennas and signal lines are disposed so as to extend across the first substrate, the bent portion, and the second substrate. CITATION LIST Patent Document Patent Document 1: International Publication No. 2020/170722 SUMMARY Technical Problems In the antenna device disclosed in International Publication No. 2020/170722 (Patent Document 1), the first substrate and the second substrate, which have different normal directions, are connected to each other via a bent portion. Consequently, the bent portion becomes dead space and there are concerns about an increase in the size of the substrate connection structure. One possible way of reducing the area required for disposing the substrate connection structure is to eliminate the bent portion and connect a side surface of the second substrate to a main surface of the first substrate, and to dispose a ground electrode and a signal line across the first substrate and the second substrate. However, if the ground electrode and the signal line are simply disposed across the first and second substrates, there will be a problem in that impedance matching will be not easy. The present disclosure has been made to solve the above-mentioned problems, and is directed to providing a substrate connection structure including a first substrate and a second substrate with different normal directions from each other that can be made small in size and configured to facilitate impedance matching. Solutions to Problems A substrate connection structure according to the present disclosure includes a first substrate and a second substrate. The second substrate has a main surface and a side surface that intersect each other. The first substrate includes an opposing surface facing the side surface of the second substrate, a first signal line disposed opposite the opposing surface, a plate-shaped first ground electrode disposed on the opposing surface or disposed opposite the opposing surface at a position between the opposing surface and the first signal line, and a first signal electrode connected to the first signal line and exposed on the opposing surface. The second substrate includes a second signal line disposed opposite the main surface, a plate-shaped second ground electrode disposed opposite the main surface at a position between the main surface and the second signal line, and a second signal electrode connected to the second signal line and exposed on the side surface and connected to the first signal electrode. The first ground electrode is configured to sandwich the first signal electrode from at least two directions when viewed in a first direction that is normal to the opposing surface. The second ground electrode includes a first portion connected to the first ground electrode and a second portion connected to the first portion. When viewed in a second direction that is a normal direction of the main surface, at least part of the first portion overlaps the second signal electrode, and the second portion does not overlap the second signal electrode. A distance in the second direction between the second signal electrode and the first portion is greater than a distance in the second direction between the second signal line and the second portion. An antenna device according to the present disclosure includes the above-described substrate connection structure. A communication device according to the present disclosure includes the above-described substrate connection structure. Advantageous Effects According to the present disclosure, a substrate connection structure including a first substrate and a second substrate having different normal directions from each other can be made small in size and configured to facilitate impedance matching. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an example of a block diagram of a communication device to which an antenna device including a substrate connection structure is applied. FIG. 2 is a diagram illustrating a connection structure between a first substrate a