JP7842631B2 - Bonded printed circuit board and method for manufacturing a bonded printed circuit board - Google Patents

Description

This invention relates to a bonded printed circuit board and a method for manufacturing a bonded printed circuit board.

Information and communication devices such as smartphones, tablet devices, and mobile phones have an antenna module for communicating with other devices and a main board on which electronic components such as semiconductor chips are mounted. A bonded printed circuit board (PCB) is used to electrically connect the antenna module and the main board. In some bonded PCBs, the two PCBs are connected at the joint via connectors such as small coaxial connectors or board-to-board connectors.

International Publication No. 2020/158810 Brochure

Bonded printed circuit boards connected via connectors have connector terminals with a small stub structure. Such a stub structure generates resonance in high-frequency signal transmission, which is necessary for high-speed digital signal transmission, significantly reducing transmission efficiency. Furthermore, when bonding printed circuit boards are placed within devices such as information and communication equipment, the increased thickness of the bonding portion due to the connector can hinder placement.

Therefore, in order to avoid the degradation of transmission characteristics due to connector connections and to save space at the joint, it is conceivable to use a bonded printed circuit board in which two printed circuit boards are directly connected via a conductive material such as solder or anisotropic conductive material. In such a bonded printed circuit board, the characteristic impedance Z of the wiring is determined by the inductance component L and the capacitance component C, and is specifically given by equation (1).

For example, the characteristic impedance Z of a printed circuit board is typically matched to 50Ω. However, in a structure where vias and the ground layer are close together at a junction, capacitance is generated between the vias and the ground layer, increasing the capacitance at the junction. This lowers the characteristic impedance at the junction, resulting in a mismatch between the characteristic impedance of the junction and the wiring portion of the printed circuit board. As a result, signal reflection occurs at the junction.

To prevent vias from coming into close proximity with the ground layer, it is conceivable to arrange the vias of two printed circuit boards facing each other. However, when joining the printed circuit boards, conductive material flows into the dimples of the opposing vias, making it difficult to ensure conductivity stability.

This invention is based on the above technical understanding, and its objective is to provide a bonded printed circuit board that can sufficiently suppress signal reflection at the joint portion and has a stable and space-saving connection structure.

A bonded printed circuit board according to a first aspect of the present invention is:
A bonded printed circuit board in which a first printed circuit board and a second printed circuit board are joined together,
The first printed circuit board has a first signal line, a first interlayer connection portion with one end connected to the first signal line, a first land extension portion extending from the other end of the first interlayer connection portion and provided on the bonding surface of the first printed circuit board, and a first ground layer provided on the bonding surface.
The second printed circuit board has a second signal line, a second interlayer connection portion with one end connected to the second signal line, a second land extension portion extending from the other end of the second interlayer connection portion and provided on the bonding surface of the second printed circuit board, and a second ground layer provided on the bonding surface.
The first signal line is electrically connected to the second signal line via the first land extension and the second land extension.
The first interlayer connection portion does not face the second ground layer of the second printed circuit board, and the second interlayer connection portion does not face the first ground layer of the first printed circuit board.

Furthermore, in the aforementioned bonded printed circuit board,
The first interlayer connection portion and the second interlayer connection portion may be arranged so as not to face each other, the first land extension portion may not extend to the opposing region of the second interlayer connection portion, the second land extension portion may not extend to the opposing region of the first interlayer connection portion, and the first land extension portion and the second land extension portion may be arranged so as to face each other.

Furthermore, in the aforementioned bonded printed circuit board,
The first land extension and the second land extension may be rectangular in plan view, and the widths of the first land extension and the second land extension may be adjusted to match the impedance between the first signal line and the second signal line.

Furthermore, in the aforementioned bonded printed circuit board,
The first interlayer connection and the second interlayer connection are arranged so as not to face each other.
The first land extension may extend to the region opposite the second interlayer connection, and/or the second land extension may extend to the region opposite the first interlayer connection.

Furthermore, in the aforementioned bonded printed circuit board,
The first land extension may have a first receiving pad portion facing the second interlayer connection portion, and the second land extension may have a second receiving pad portion facing the first interlayer connection portion.

Furthermore, in the aforementioned bonded printed circuit board,
The first receiving pad portion may encompass the opposing region of the second interlayer connection portion, and the second receiving pad portion may encompass the opposing region of the first interlayer connection portion.

Furthermore, in the aforementioned bonded printed circuit board,
The first land extension and the second land extension may be arranged to face each other, and the first interlayer connection and the second interlayer connection may be arranged to face each other.

Furthermore, in the aforementioned bonded printed circuit board,
The first interlayer connection portion and/or the first land extension portion is electrically connected to the second interlayer connection portion and/or the second land extension portion via a conductive material, the conductive material may be an anisotropic conductive film, anisotropic conductive paste, solder, or conductive paste.

Furthermore, in the aforementioned bonded printed circuit board,
The first interlayer connection and/or the first land extension and the second interlayer connection and/or the second land extension are directly electrically connected.
The first printed circuit board and the second printed circuit board are joined together by a non-conductive material, which may be a non-conductive film, a non-conductive paste, or an adhesive.

Furthermore, in the aforementioned bonded printed circuit board,
The first printed circuit board and/or the second printed circuit board may be flexible printed circuit boards.

Furthermore, in the aforementioned bonded printed circuit board,
The insulating substrate of the flexible printed circuit board may include a liquid crystal polymer, a fluorine-based material, or a polyimide-based material.

Furthermore, in the aforementioned bonded printed circuit board,
The first printed circuit board may be connected to an antenna module including an antenna and an antenna substrate, and the second printed circuit board may be connected to a main board on which a semiconductor chip that performs information processing based on signals received by the antenna is mounted.

A bonded printed circuit board according to a second aspect of the present invention is:
A bonded printed circuit board in which a first printed circuit board and a second printed circuit board are joined together,
The first printed circuit board has a plurality of first signal lines, a plurality of first interlayer connection portions with one end connected to the plurality of first signal lines, a plurality of first land extension portions extending from the other ends of the plurality of first interlayer connection portions and provided on the bonding surface of the first printed circuit board, and a first ground layer provided on the bonding surface.
The second printed circuit board has a plurality of second signal lines, a plurality of second interlayer connection portions with one end connected to the plurality of second signal lines, a plurality of second land extension portions extending from the other ends of the plurality of second interlayer connection portions and provided on the bonding surface of the second printed circuit board, and a second ground layer provided on the bonding surface.
Each of the plurality of first signal lines is electrically connected to the corresponding second signal line among the plurality of second signal lines via the corresponding first land extension and the second land extension.
The plurality of first interlayer connections are characterized in that they do not face the second ground layer of the second printed circuit board, and the plurality of second interlayer connections are characterized in that they do not face the first ground layer of the first printed circuit board.

Furthermore, in the aforementioned bonded printed circuit board,
The plurality of first interlayer connecting portions may be arranged in a staggered pattern along a predetermined direction.

Furthermore, in the aforementioned bonded printed circuit board,
The first interlayer connection portion and the first land extension portion may be arranged such that the line connecting the first interlayer connection portion and the first land extension portion intersects obliquely with respect to the width direction of the first printed circuit board.

Furthermore, in the aforementioned bonded printed circuit board,
The plurality of first interlayer connection portions and the plurality of first land extension portions may be arranged along the longitudinal direction of the first printed circuit board.

Furthermore, in the aforementioned bonded printed circuit board,
A ground via may be provided between at least one pair of the aforementioned plurality of first interlayer connections.

Furthermore, in the aforementioned bonded printed circuit board,
The ground vias may be arranged so as to be surrounded by the plurality of first interlayer connections.

Furthermore, in the aforementioned bonded printed circuit board,
Each of the plurality of first land extensions has a receiving pad portion facing the corresponding second interlayer connection portion.
The plurality of first interlayer connecting portions and/or the plurality of receiving pad portions may be arranged in a triangular grid pattern.

Furthermore, in the aforementioned bonded printed circuit board,
At least one of the plurality of first land extensions may further have a connecting portion that connects the receiving pad portion and the first interlayer connecting portion.

Furthermore, in the aforementioned bonded printed circuit board,
Each of the plurality of first interlayer connections may be separated by the first ground layer.

The method for manufacturing a bonded printed circuit board according to the present invention is:
A step of manufacturing a first printed circuit board having a first signal line, a first interlayer connection portion with one end connected to the first signal line, a first land extension portion extending from the other end of the first interlayer connection portion, and a first ground layer provided on the same plane as the first land extension portion.
A process for manufacturing a second printed circuit board having a second signal line, a second interlayer connection portion with one end connected to the second signal line, a second land extension portion extending from the other end of the second interlayer connection portion, and a second ground layer provided on the same plane as the second land extension portion.
A step of joining the first printed circuit board and the second printed circuit board such that the first signal line is electrically connected to the second signal line via the first land extension and the second land extension, the first interlayer connection does not face the second ground layer of the second printed circuit board, and the second interlayer connection does not face the first ground layer of the first printed circuit board,
It is characterized by having the following features.

According to the present invention, it is possible to provide a bonded printed circuit board with a stable and space-saving connection structure that can sufficiently suppress signal reflection at the joint portion.

This is a perspective view of a bonded printed circuit board according to the first embodiment. This is an enlarged view of the joint portion J in Figure 1A. This is a longitudinal cross-sectional view (first example) of a bonded printed circuit board along the signal lines according to the first embodiment. This is a longitudinal cross-sectional view (second example) of a bonded printed circuit board along the signal lines according to the first embodiment. This is a perspective view of the bonding surface of one of the printed circuit boards in the bonded printed circuit board according to the first embodiment. This is a cross-sectional view illustrating a process for manufacturing a bonded printed circuit board according to the first embodiment. Figure 4 is a cross-sectional view illustrating the manufacturing method of a bonded printed circuit board according to the first embodiment. Figure 5 is a cross-sectional view illustrating the manufacturing method of a bonded printed circuit board according to the first embodiment. Figure 6 is a cross-sectional view illustrating the manufacturing method of a bonded printed circuit board according to the first embodiment. This figure shows the simulation results of the transmission characteristics of the bonded printed circuit board according to the first embodiment. This is a plan view of the bonding surface of one printed circuit board in a bonded printed circuit board according to Modification 1 of the first embodiment. This is a longitudinal cross-sectional view along the signal lines of a bonded printed circuit board according to a modified example 2 of the first embodiment. This is a perspective view of the bonding surface of one of the printed circuit boards in the bonded printed circuit board according to the second embodiment. This is a longitudinal cross-sectional view of a bonded printed circuit board according to the second embodiment, along the signal lines. This is a plan view of the bonding surface of one of the printed circuit boards in a bonded printed circuit board according to a modified example 1 of the second embodiment. This is a plan view of the bonding surface of one of the printed circuit boards in a bonded printed circuit board according to a modified example 2 of the second embodiment. This is a plan view of the bonding surface of one of the printed circuit boards in a bonded printed circuit board according to a modified example 3 of the second embodiment. This is a plan view of the bonding surface of one of the printed circuit boards in a bonded printed circuit board according to a modified example 4 of the second embodiment. This is a plan view of the bonding surface of one of the printed circuit boards in a bonded printed circuit board according to a modified example 5 of the second embodiment. This is a plan view of the bonding surface of one of the printed circuit boards in a bonded printed circuit board according to a modified example 6 of the second embodiment. This is a longitudinal cross-sectional view of a bonded printed circuit board according to the third embodiment, along the signal lines.

The embodiments of the present invention will be described below with reference to the drawings. In each drawing, components having equivalent functions are denoted by the same reference numerals. Furthermore, the scale ratio of each component has been appropriately adjusted to ensure recognizable size in the drawings, and does not necessarily correspond to actual dimensions.

(First embodiment)
The bonded printed circuit board 1 according to the first embodiment will be described with reference to Figures 1A to 3. Figure 1A is a perspective view of the bonded printed circuit board 1 according to the first embodiment. Figure 1B is an enlarged view of the bonded portion J in Figure 1A. Figures 2A and 2B are two examples of longitudinal cross-sectional views of the bonded printed circuit board 1 along the signal lines 11 and 21. Figure 3 is a perspective view of the bonded surface of the printed circuit board 10 (20) of the bonded printed circuit board 1.

As shown in Figure 1A, the bonded printed circuit board 1 comprises a printed circuit board 10 and a printed circuit board 20 that are bonded together. In this embodiment, the printed circuit boards 10 and 20 are flexible printed circuit boards. However, at least one of the printed circuit boards 10 and 20 may be a rigid printed circuit board.

The bonded printed circuit board 1 is used, for example, in information and communication devices such as smartphones to electrically connect an antenna module and a main board. In this case, the printed circuit board 10 is connected to, for example, an antenna module (not shown). The antenna module includes an antenna and an antenna board on which the antenna is mounted. The printed circuit board 20 is connected to, for example, a main board (not shown) on which a semiconductor chip that performs information processing based on signals received by the antenna is mounted.

Furthermore, the printed circuit board 10 itself may be the antenna board. Also, the printed circuit board 20 itself may be the main board on which semiconductor chips are mounted.

As shown in Figure 1A, signal lines 11 are provided on the printed circuit board 10, and signal lines 21 are provided on the printed circuit board 20. Furthermore, at least one pair of ground lines 41 are provided on the printed circuit board 10 parallel to the signal lines 11. These ground lines 41 are electrically connected to the outer ground layer (ground layers 17, 17A, described later) of the printed circuit board 10 via ground vias 42.

Similarly, the printed circuit board 20 is provided with at least one pair of ground lines 51 parallel to the signal lines 21. These ground lines 51 are electrically connected to the outer ground layer of the printed circuit board 20 (ground layer 27 and/or ground layer 27A, described later) via ground vias 52.

Note that the arrangement of signal lines 11, 21 and ground lines 41, 51 shown in Figure 1A is just one example, and other arrangements are also possible. For example, signal line 11 may extend in a direction oblique to the longitudinal direction of the printed circuit board 10 and be connected to the interlayer connection 12. Also, signal line 11 is not limited to a straight line and may be bent along the way. The same applies to signal line 21. The same applies to the following embodiments and modifications.

As shown in Figure 1A, the signal line 11 of the printed circuit board 10 and the signal line 21 of the printed circuit board 20 are electrically connected at the joint J. The connection of the signal lines at the joint J will be explained in detail with reference to Figure 1B. Figure 1B is an enlarged view of the joint J.

As shown in Figure 1B, the signal line 11 is connected to one end (lower end) of the interlayer connection section 12. The interlayer connection section 12 has a land 13. The land extension 14 extends from the other end (upper end) of the interlayer connection section 12. In other words, the land extension 14 extends from the land 13.

Similarly, the signal line 21 is connected to one end (upper end) of the interlayer connection section 22. The interlayer connection section 22 has a land 23. The land extension 24 extends from the other end (lower end) of the interlayer connection section 22. In other words, the land extension 24 extends from the land 23.

The land extension 14 is provided on the bonding surface of the printed circuit board 10 (the surface including the land 13, the ground layer 17 (described later), and the opposing region A1). Similarly, the land extension 24 is provided on the bonding surface of the printed circuit board 20 (the surface including the land 23, the ground layer 27 (described later), and the opposing region A2).

Furthermore, the land extensions 14 and 24 may extend from the lands 13 and 23 on the joint surface in a direction different from the direction in which the signal lines 11 and 21 extend. They may also extend in multiple directions, or the lands 13 and 23 may have a partially enlarged diameter. The same applies to subsequent embodiments and modifications.

In this embodiment, the interlayer connection portions 12 and 22 are plated vias formed by plating the inner walls of bottomed via holes. The configuration of the interlayer connection portions 12 and 22 is not particularly limited; they may be filled vias, through-holes, or the like.

The land extensions 14 and 24 are arranged so that at least a portion of them overlap when viewed in the thickness direction of the bonded printed circuit board 1. In this embodiment, as shown in Figure 1B, the land extensions 14 and 24 are arranged so that their tip portions overlap. Alternatively, the land extensions 14 and 24 may be arranged to overlap completely.

As described later, in this embodiment and the second embodiment, the land extension 14 and the land extension 24 are electrically connected by a conductive material. Therefore, the signal line 11 is electrically connected to the signal line 21 via the land extension 14 and the land extension 24.

Next, the cross-sectional structure of the bonded printed circuit board 1 according to this embodiment will be described. Figures 2A and 2B show two examples of longitudinal cross-sectional views of the bonded printed circuit board 1 along the signal lines 11 and 21. In the example in Figure 2A, an anisotropic conductive film (ACF) is used as the conductive material 30, and the printed circuit board 10 and the printed circuit board 20 are bonded together. In the example in Figure 2B, the signal lines 11 and 21 are electrically connected by a conductive paste 30a, and the conductive pastes 30a are insulated from each other by a non-conductive material 31.

As shown in Figures 2A and 2B, in this embodiment, the printed circuit board 10 is formed by bonding insulating substrates 18A and 18B via an adhesive layer 19. A ground layer 17 is provided on the joint surface of the printed circuit board 10, i.e., on the upper surface of the insulating substrate 18A. Furthermore, the ground layer 17 is formed to surround the interlayer connection portion 12. Additionally, a ground layer 17A is provided on the lower surface of the insulating substrate 18B.

The signal line 11 is provided on the lower surface of the insulating substrate 18A. The end of the signal line 11 is connected to one end of the interlayer connection portion 12, which is provided so as to penetrate the insulating substrate 18A.

The land extension portion 14 extending from the other end of the interlayer connection portion 12 is provided on the upper surface of the insulating substrate 18A. More specifically, the land extension portion 14 extends from the land 13 of the interlayer connection portion 12. In this embodiment, the land extension portion 14 extends from the interlayer connection portion 12 along the direction in which the signal line 11 extends.

Similarly, the printed circuit board 20 is constructed by bonding insulating substrates 28A and 28B together via an adhesive layer 29. A ground layer 27 is provided opposite the ground layer 17. More specifically, the ground layer 27 is provided on the bonding surface of the printed circuit board 20, i.e., on the lower surface of the insulating substrate 28A. Furthermore, the ground layer 27 is formed to surround the interlayer connection portion 22. Additionally, a ground layer 27A is provided on the upper surface of the insulating substrate 28B.

The signal line 21 is provided on the upper surface of the insulating substrate 28A. The end of the signal line 21 is connected to one end of an interlayer connection portion 22, which is provided so as to penetrate the insulating substrate 28A.

The land extension portion 24 extending from the other end of the interlayer connection portion 22 is provided on the lower surface of the insulating substrate 28A. More specifically, the land extension portion 24 extends from the land 23 of the interlayer connection portion 22. In this embodiment, the land extension portion 24 extends from the interlayer connection portion 22 along the direction in which the signal line 21 extends.

In this embodiment, the materials of the insulating substrates 18A, 18B, 28A, and 28B are liquid crystal polymers (LCP). However, the materials of the insulating substrates 18A, 18B, 28A, and 28B are not limited to LCP; for example, fluorine-based materials such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) and PTFE (polytetrafluoroethylene), or polyimide-based materials such as modified polyimide (MPI) and polyimide (PI) may also be used. Furthermore, the materials of the insulating substrates 18A, 18B, 28A, and 28B can be independently and arbitrarily selected.

To ensure the transmission characteristics of high-frequency signals, it is desirable to use materials with low dielectric constant and low dielectric loss tangent as the insulating substrate material. Similarly, it is desirable to use materials with low dielectric constant and low dielectric loss tangent for the adhesive layers 19 and 29.

As shown in Figures 2A and 2B, the land extension 14 and the land extension 24 are electrically connected via a conductive material 30. In this embodiment, the conductive material 30 is an anisotropic conductive film (ACF) or anisotropic conductive paste (ACP).

The conductive material 30 may be solder such as solder paste or conductive paste. In this case, as shown in Figure 2B, insulation between the conductive pastes 30a may be provided by the non-conductive material 31. Solder may be used instead of conductive paste 30a. As the non-conductive material 31, for example, a non-conductive film (NCF), a non-conductive paste (NCP), or an adhesive (including a low-tack agent) can be used. The same applies to the following embodiments and modifications.

As shown in Figures 2A and 2B, the region of the printed circuit board 10 facing the interlayer connection portion 22 of the printed circuit board 20 (hereinafter referred to as "facing region A1") does not have a ground layer 17. Therefore, the interlayer connection portion 22 of the printed circuit board 20 does not face the ground layer 17 of the printed circuit board 10.

Similarly, in the printed circuit board 20, the region facing the interlayer connection portion 12 of the printed circuit board 10 (hereinafter referred to as "facing region A2") does not have a ground layer 27. Therefore, the interlayer connection portion 12 of the printed circuit board 10 does not face the ground layer 27 of the printed circuit board 20.

Thus, in this embodiment, a ground layer is not provided in the region opposite the interlayer connection, and the interlayer connection and the ground layer are not in close proximity. Therefore, a decrease in characteristic impedance due to an increase in the capacitance component of the printed circuit board can be avoided.

As shown in Figures 1B, 2A, and 2B, in this embodiment, the interlayer connection portion 12 and interlayer connection portion 22 of the printed circuit board 10 are arranged so as not to face each other, and the land extension portion 14 does not extend to the opposing region A1 of the interlayer connection portion 22. Similarly, the land extension portion 24 of the printed circuit board 20 does not extend to the opposing region A2 of the interlayer connection portion 22. Then, as shown in Figures 2A and 2B, the land extension portion 14 and land extension portion 24 are arranged to face each other and are connected by a conductive material 30 or conductive paste 30a.

Next, the land extension portion will be described with reference to Figure 3. Figure 3 is a perspective view of the bonding surface of the printed circuit board 10 (20) of the bonded printed circuit board 1. As mentioned above, the bonding surface of the printed circuit board 10 is the surface that includes the land 13, the land extension portion 14, the ground layer 17, and the opposing region A1.

In this embodiment, the land extension portion 14 (24) is rectangular in plan view and extends with a constant width L from the interlayer connection portion 12 (22) to the front of the opposing region A1 (A2). As shown in Figure 3, the tip of the land extension portion 14 (24) may be rounded. The width L of each land extension portion 14 (24) is adjusted to achieve impedance matching with the signal line 11 (21). In this embodiment, the width L of the land extension portion 14 (24) is set to 192 μm to match the characteristic impedance (50 Ω) of the printed circuit board 10 (20).

Furthermore, the land extension 14 may extend to the opposing region A1. Similarly, the land extension 24 may extend to the opposing region A2. This allows for more stable conductivity between signal line 11 and signal line 21.

Furthermore, the size and shape of the portion where the land extension 14 (24) extends in the area where the ground layer 17 (27) has been removed are not limited to the approximately circular shape shown in Figure 3. For example, as shown in Figure 9 later, the portion may be channel-shaped with narrowing on both sides of the land extension 14 (24) to match the shape of the land extension 14 (24), or it may be a polygonal shape or various other deformations are possible. The size and shape of the gap between the land extension 14 (24) and the ground layers 17 (27) on both sides can also be varied.

Furthermore, the joint surface may have multiple surfaces. For example, it may have a first surface and a second surface connected by a step, with a land extension 14 (24) provided on the first surface and a ground layer 17 (27) provided on the second surface. Alternatively, a step may exist in the ground layer 17 (27), and the ground layer 17 (27) may span both the first and second surfaces. The same applies to subsequent embodiments and modifications.

(Method of manufacturing a bonded printed circuit board)
Next, with reference to Figures 4 to 7, an example of a manufacturing method for the printed circuit board 10 (20) that constitutes the bonded printed circuit board 1 will be described.

As shown in Figure 4(1), a single-sided metal foil laminate 100 is prepared, having an insulating substrate 110 and a metal foil 120 provided on the upper surface of the insulating substrate 110. The insulating substrate 110 is an insulating film (for example, 100 μm thick) made of liquid crystal polymer (LCP) or the like. The metal foil 120 is copper foil (for example, 12 μm thick). Note that the insulating substrate 110 is not limited to LCP; for example, it may be a fluorine-based material such as PFA or PTFE, or a polyimide-based material such as MPI or PI. Furthermore, the metal foil 120 may be a metal foil made of a metal other than copper (silver, aluminum, etc.).

Next, as shown in Figure 4(2), an adhesive layer 130 is formed on the underside of the insulating substrate 110. The adhesive layer 130 may be formed by applying adhesive to the underside of the insulating substrate 110, or by laminating an adhesive film to the insulating substrate 110. Alternatively, the adhesive layer 130 may be formed by laminating an adhesive-coated protective film (with an adhesive layer formed on one side) to the underside of the insulating substrate 110, and then peeling off the protective film.

As shown in Figure 4(3), a double-sided metal foil laminate 200 is prepared, comprising an insulating substrate 210, a metal foil 220 provided on the upper surface of the insulating substrate 210, and a metal foil 230 provided on the lower surface of the insulating substrate 210. The insulating substrate 210 is an insulating film (for example, 100 μm thick) made of liquid crystal polymer (LCP) or the like. The metal foils 220 and 230 are copper foils (for example, 12 μm thick). Note that the insulating substrate 210 is not limited to LCP; for example, it may be a fluorine-based material such as PFA or PTFE, or a polyimide-based material such as MPI or PI. Furthermore, the metal foils 220 and 230 may be metal foils made of metals other than copper (silver, aluminum, etc.).

Next, as shown in Figure 4(4), the metal foil 220 of the double-sided metal foil laminate 200 is patterned using a known photofabrication method to form signal lines 220a and ground lines 220b. Signal line 220a corresponds to the aforementioned signal line 11(21), and ground line 220b corresponds to the aforementioned ground line 41(51).

Next, the second wiring board obtained in the process described in the process described in the section

Next, as shown in Figure 5(2), a laser beam is irradiated onto a predetermined area of the laminate to form via holes H1 and H2. More specifically, first, metal foils 120 and 230 are processed to form a conformal mask with openings at the positions where via holes H1 and H2 will be formed. Then, by irradiating the openings of the metal foils 120 and 230 with laser pulses, the insulating substrates 110 and 210 (and in the case of forming via hole H1, the adhesive layer 130) exposed at the openings are removed. Alternatively, via holes may be formed using methods such as the window method or direct drilling instead of the conformal mask method.

The laser beam used is, for example, an infrared laser such as a carbon dioxide laser, or a UV-YAG laser. The diameter of the via holes H1 and H2 is, for example, 150 μm. Subsequently, a desmear treatment is performed to remove resin residue at the boundary between the adhesive layer 130 and the signal line 220a, and the treatment film (e.g., Ni/Cr film) on the back surface of the ground line 220b. In this way, via hole H1 with the signal line 220a exposed on its bottom surface, and via hole H2 with the ground line 220b exposed on its bottom surface are formed.

Next, as shown in Figure 5(2), a through-hole H3 is formed using a drill, penetrating the laminate in the thickness direction. Note that the order in which via holes H1, H2, and through-hole H3 are formed is arbitrary.

Next, as shown in Figure 6(1), vias 310, 320, and plated through-holes 330 are formed by forming a metal plating layer (for example, a copper plating layer) on the inner walls of via holes H1, H2 and through-hole H3.

This process is carried out, for example, by a panel plating method in which copper plating is applied to the entire laminate, or by a button plating (pattern plating) method in which copper plating is applied only to predetermined areas of the laminate. The latter method involves laminating a dry film onto the laminate, then exposing and developing the dry film, and finally applying plating to the areas not covered by the dry film. Figure 6(1) shows the case where a plating layer is formed only in the areas of via holes H1, H2 and through-hole H3 by button plating.

Via 310 corresponds to the interlayer connection portion 12 (22) described above. Via 320 and the plated through-hole 330 correspond to the ground via 42 (52) described above or the ground via 16 described later.

Via 310 electrically connects signal line 220a to metal foil 120. Via 320 electrically connects ground line 220b to metal foil 230. Plated through-hole 330 electrically connects ground line 220b, metal foil 120, and metal foil 230.

Although not shown in the figures, vias may be formed to electrically connect the ground wire 220b and the metal foil 120, corresponding to the aforementioned ground via 42 (52) or the ground via 16 described later.

Furthermore, vias 310 and 320 may be vias other than those described above, such as filled vias, staggered vias, or stacked vias. The configurations of vias 310 and 320 may also differ from each other. Alternatively, instead of the plated through-hole 330, conductive material may be filled into the through-hole H3 to form an interlayer connection for electrically connecting the ground wire 220b, metal foil 120, and metal foil 230.

Next, as shown in Figure 6(2), the metal foil 120 is patterned using a known photofabrication method. This forms the lands 13(23), land extensions 14(24), and ground layer 17(27) described above. Furthermore, the metal foil 230 is patterned using a known photofabrication method. This forms the ground layer 17A(27A) described above. The patterning of the metal foil 120 also forms the receiving pad portion 15(25) and connecting portion (line) 14A described in the second embodiment and its modified form.

Next, as shown in Figures 7(a) and 7(b), a protective film 140 is laminated to the upper surface of the laminate to cover the patterned metal foil 120, and a protective film 240 is laminated to the lower surface of the laminate to cover the patterned metal foil 230. The protective films 140 and 240 are made of insulating material; for example, polyimide-based materials and photosensitive photoresists are applicable.

Next, as shown in Figures 7(a) and 7(b), openings 410 and 430 are formed in the protective film 140, and an opening 420 is formed in the protective film 240. The metal foil electrically connected to the ground line 220b is exposed through openings 410 and 420, and the metal foil electrically connected to the signal line 220a is exposed through opening 430.

Finally, as shown in Figures 7(a) and 7(b), the metal foil exposed in the openings 410, 420, and 430 is gold-plated to form plating layers 410A, 420A, and 430A. Plating protects the exposed metal foil in an electrically connectable state. The plating layers 410A, 420A, and 430A may be alloys such as Ni/Au plating. Alternatively, surface treatment with an aqueous preflux or the like may be performed instead of gold plating.

Through the above process, the printed circuit board 300 shown in Figures 7(a) and 7(b) is obtained. The printed circuit board 300 corresponds to the previously mentioned printed circuit board 10(20).

Note that the cross-sectional views shown in Figures 2A and 2B, and later in Figures 10, 12, and 19, do not show the components corresponding to the protective films 140, 240, the openings 410, 420, 430, and the plating layers 410A, 420A, 430A.

A bonded printed circuit board 1 can be obtained by joining the two printed circuit boards 300 obtained as described above via a conductive material such as ACF. Specifically, the two printed circuit boards 300 are joined such that the plating layer 430A of one printed circuit board 300 and the plating layer 430A of the other printed circuit board 300 are electrically connected via the conductive material. This results in a bonded printed circuit board where the signal lines 220a of each printed circuit board 300 are electrically connected via two vias 310.

When using ACF as a conductive material, first, the ACF is applied to the joint area of the printed circuit boards 10 and 20 at a temperature below the ACF curing temperature (temporary bonding), and then the ACF is cured by heating it to a temperature above the curing temperature.

Furthermore, when using solder paste or conductive paste as the conductive material, the solder paste or conductive paste is placed at the predetermined connection position by printing or other means, and then a non-conductive film, non-conductive paste, or adhesive (a low-tack adhesive may also be used) is applied. Afterward, the printed circuit boards 10 and 20 are aligned and stacked, and the joint area is heated with a pulse heater to melt the conductive material.

In the above manufacturing method, the insulating substrate 110 and the insulating substrate 210 were bonded using an adhesive. However, the insulating substrates 110 and 210 may also be bonded without using an adhesive by heating and pressurizing them at a temperature above their melting points.

As described above, in the bonded printed circuit board 1 according to this embodiment, the interlayer connection portion 12 does not face the ground layer 27 of the printed circuit board 20, and the interlayer connection portion 22 does not face the ground layer 17 of the printed circuit board 10. Therefore, it is possible to avoid a decrease in the characteristic impedance of the bonded printed circuit board due to an increase in the capacitance component of the printed circuit board.

Here, the characteristics of the bonded printed circuit board 1 according to this embodiment are evaluated using the simulation software HFSS (Ansys). Figure 8(a) shows the simulation results of the characteristic impedance using the Time Domain Reflectometry (TDR) method. Figure 8(b) shows the simulation results of the frequency dependence of the Voltage Standing Wave Ratio (VSWR) of the bonded printed circuit board 1.

As shown in Figure 8(a), the characteristic impedance does not decrease at the junction J (indicated by the arrow in the figure). Furthermore, as shown in Figure 8(b), the voltage standing wave ratio of the junction printed circuit board 1 is sufficiently low across the entire frequency range of 0 to 30 GHz, indicating that the characteristic impedance is matched. Thus, based on the evaluation results of TDR and VSWR, which represent the transmission characteristics, the junction printed circuit board 1 according to this embodiment does not experience a decrease in characteristic impedance at the junction J, and can sufficiently suppress signal reflection at the junction.

Furthermore, in the bonded printed circuit board 1 according to this embodiment, the signal lines 11 and 21 of the printed circuit boards 10 and 20 are electrically connected via the land extensions 14 and 24, thus enabling a stable connection between the signal line 11 of the printed circuit board 10 and the signal line 21 of the printed circuit board 20. Also, because the printed circuit boards 10 and 20 are directly bonded without the use of a board-to-board connector, resonance caused by minute stubs in high-frequency signals is prevented, thus preventing a decrease in transmission characteristics.

Furthermore, compared to joining printed circuit boards via connectors such as board-to-board connectors, this design results in a space-saving structure with reduced thickness at the joint.

Therefore, according to this embodiment, it is possible to provide a bonded printed circuit board with a stable and space-saving connection structure that can sufficiently suppress signal reflection at the joint portion.

Furthermore, according to the manufacturing method of this embodiment, the signal lines 11 and 21 of the printed circuit boards 10 and 20 are electrically connected via the land extensions 14 and 24. This prevents the conductive material 30 from filling the dimples on the surface of the interlayer connection portions 12 and 22, which would otherwise lead to unstable conductivity between the printed circuit boards 10 and 20. As a result, the manufacturability and yield of the bonded printed circuit boards can be improved.

In the above description, the printed circuit boards 10 and 20 were assumed to have a three-layer structure, and the signal lines were configured as high-speed transmission lines using striplines. However, the number of layers and the configuration of the signal lines are not limited to these. For example, the signal lines may be wiring formed on the surface of an insulating substrate, such as in a microstrip line structure. In this case, the microstrip line may be configured as a microstrip antenna or as a transmission line.

Furthermore, although the above description described a bonded printed circuit board 1 as being formed by joining two printed circuit boards 10 and 20, it may also have multiple joints formed by sequentially joining three or more printed circuit boards.

Furthermore, multiple printed circuit boards are not limited to being joined with their longitudinal directions parallel; they may also be joined at right angles or diagonally.

Next, two modified examples of the first embodiment will be described. The effects of the first embodiment can be obtained by any of these modified examples.

(Modification 1 of the first embodiment)
Referring to Figure 9, a modification 1 of the first embodiment will be described. Figure 9 is a plan view of the bonding surface of the printed circuit board 10 of the bonded printed circuit board 1 according to this modification.

This modified example relates to the case where printed circuit boards 10 and 20 have multiple signal lines. As shown in Figure 9, printed circuit board 10 has, for each signal line 11, an interlayer connection portion 12, a land 13, and a land extension portion 14 extending from the interlayer connection portion 12. In other words, the land extension portion 14 extends from the land 13. The end of each signal line 11 is connected to one end of the corresponding interlayer connection portion 12. Each interlayer connection portion 12 has a land 13. The land extension portion 14 extends from the other end of each interlayer connection portion 12. Printed circuit board 20, although not shown, has a similar configuration. This makes it possible to construct a bonded printed circuit board in which the multiple signal lines 11 of printed circuit board 10 and the multiple signal lines 21 of printed circuit board 20 are electrically connected. Note that the number of interlayer connection portions 12 is not limited to four and may be increased or decreased according to the required number of signal lines.

As shown in Figure 9, the multiple signal lines 11 extend parallel to each other along the extension direction (vertical direction in the figure) of the land extension 14.

As described above, in this modified example, each of the multiple signal lines 11 is electrically connected to the corresponding signal line 21 among the multiple signal lines 21 via the corresponding land extension 14, conductive material 30, and land extension 24.

As shown in Figure 9, in this modified example, similar to the first embodiment, a ground layer 17 is not provided in the opposing region A1 of the printed circuit board 10. Therefore, the interlayer connection portion 22 of the printed circuit board 20 does not face the ground layer 17 of the printed circuit board 10. Similarly, since a ground layer 27 is not provided in the opposing region A2 of the printed circuit board 20, the interlayer connection portion 12 of the printed circuit board 10 does not face the ground layer 27 of the printed circuit board 20. Therefore, similar to the first embodiment, a decrease in characteristic impedance due to an increase in the capacitance component of the printed circuit board can be avoided.

Furthermore, as shown in Figure 9, in this modified example, multiple interlayer connection portions 12 are arranged in a staggered pattern along the width direction (horizontal direction in the figure) of the printed circuit board 10, and the land extension portions 14 extend in the same direction (upward in the figure). Because the multiple interlayer connection portions 12 are arranged in such a zigzag pattern that the line connecting their centers forms a zigzag shape, this modified example allows for a reduction in the area of the connection portion.

Furthermore, multiple interlayer connection sections 12 may be arranged in a staggered pattern along the longitudinal direction (vertical direction in the figure) of the printed circuit board 10.

Furthermore, although Figure 9 shows multiple land extensions 14 extending toward the same side (upper side in the figure), at least one land extension 14 may extend toward the opposite side (lower side in the figure). For example, the land extensions 14 of adjacent inter-story connection sections 12 may alternately extend toward opposite sides.

Furthermore, as shown in Figure 9, each interlayer connection 12 is separated by a separator S in the ground layer 17. That is, each interlayer connection 12 is located in one of the multiple openings provided in the ground layer 17. By separating the interlayer connection 12 with the separator S, crosstalk between signal lines can be reduced. Moreover, by connecting the ground layer 17 and the ground layer 27 to each other via the conductive material 30 in the separator S, unnecessary stubs in the ground layer can be eliminated.

Furthermore, as shown in Figures 15 and 18 described later, the separate section S may not be provided. The same applies to other embodiments and modifications.

Furthermore, the joining surface may have multiple surfaces. For example, the joining surface may have a first surface and a second surface connected by a step, with one land extension 14 from among the multiple land extensions 14 provided on the first surface and another land extension 14 from among the multiple land extensions 14 provided on the second surface. The same applies to subsequent embodiments and modifications.

According to this modified example, since the bonded printed circuit board 1 includes multiple signal lines 11 and 21, it is possible to provide a bonded printed circuit board that can accommodate cases where four signal lines are required or where two sets of differential lines are needed.

Furthermore, by arranging multiple interlayer connection sections 12 in a staggered pattern, the area of the connection section can be reduced.

(Modification 2 of the first embodiment)
Referring to Figure 10, a modified example of the first embodiment, a bonded printed circuit board 1, will be described. Figure 10 is a longitudinal cross-sectional view of the bonded printed circuit board 1 according to this modified example, along the signal lines.

As shown in Figure 10, in this modified example, the interlayer connection portion 12 of the printed circuit board 10 and the interlayer connection portion 22 of the printed circuit board 20 are arranged to face each other. Furthermore, the land extension portion 14 of the printed circuit board 10 and the land extension portion 24 of the printed circuit board 20 are also arranged to face each other.

As described above, in the connection structure according to this modified example, the interlayer connection portions face each other, but the signal line 11 and the signal line 21 are electrically connected via the land extension portions 14 and 24. Therefore, even if the conductive material 30 is filled into the dimples on the surface of the interlayer connection portions 12 and 22, causing the conductivity between the interlayer connection portions 12 and 22 to become unstable, the land extension portions 14 and 24 can ensure conductivity between the signal lines 11 and 21. The area of the land extension portions 14 and 24 should preferably be as small as possible while still ensuring conductivity between the signal lines 11 and 21.

(Second embodiment)
Next, a bonded printed circuit board 1 according to the second embodiment will be described with reference to Figures 11 and 12. Figure 11 is a perspective view of the bonding surface of the printed circuit board 10 (20) of the bonded printed circuit board according to the second embodiment. Here, the bonding surface is the surface including the ground layer 17 (27), the land 13 (23), and the receiving pad portion 15 (25). Figure 12 is a longitudinal cross-sectional view of the bonded printed circuit board according to the second embodiment along the signal lines.

One of the differences between the first and second embodiments is that in the second embodiment, the land extension has a receiving pad portion formed to encompass the opposing region. That is, the area of the receiving pad portion is greater than or equal to the combined area of the lands and via portions of the opposing interlayer connection portions. The second embodiment will now be described, focusing on these differences.

As shown in Figure 11, a receiving pad portion 15 is provided as a land extension portion extending from the land 13 of the interlayer connection portion 12 of the printed circuit board 10. This receiving pad portion 15 is formed to encompass the opposing region A1. As shown in Figure 12, the receiving pad portion 15 faces the interlayer connection portion 22. Similarly, a receiving pad portion 25 is provided as a land extension portion 24 of the printed circuit board 20. The receiving pad portion 25 is formed to encompass the opposing region A2 and faces the interlayer connection portion 12 of the printed circuit board 10.

In this embodiment, the diameter of the receiving pads 15 and 25 is 400 μm, and the diameter of the lands 23 and 13 is 350 μm. The area of the receiving pads is larger than the area of the opposing region. As a result, even if there is some misalignment in the stacking of the printed circuit boards 10 and 20, the lands 13 and 23 do not protrude from the receiving pads 25 and 15 when viewed in the thickness direction of the printed circuit boards 10 and 20. This ensures conductivity between signal lines and prevents impedance mismatch and variations.

As shown in Figure 12, the receiving pad portion 15 of the printed circuit board 10 is joined to the interlayer connection portion 22 and land 23 of the printed circuit board 20 via the conductive material 30. Furthermore, the receiving pad portion 25 of the printed circuit board 20 is joined to the interlayer connection portion 12 and land 13 of the printed circuit board 10 via the conductive material 30.

According to the above bonding structure, since the interlayer connection portion and the receiving pad portion are arranged to face each other on each of the printed circuit boards 10 and 20, the fluidity of the conductive material 30, such as ACF, during the bonding process is reduced compared to a bonding structure where the interlayer connection portions 12 and 22 are butted together, resulting in stable conductivity. Furthermore, since the receiving pad portion has a relatively large area to encompass the opposing region, connection reliability can be improved compared to the first embodiment.

Next, we will describe modified examples 1 to 5 according to the second embodiment. The effects of the second embodiment can be obtained by any of these modified examples.

(Modification 1 of the second embodiment)
Referring to Figure 13, a modified example of the second embodiment, a bonded printed circuit board 1, will be described. Figure 13 is a plan view of the bonding surface of the printed circuit board 10 of the bonded printed circuit board 1 according to this modified example.

This modified example relates to a case where the printed circuit boards 10 and 20 have multiple signal lines, similar to Modification 1 of the first embodiment. As shown in Figure 13, the printed circuit board 10 has, for each signal line 11, an interlayer connection portion 12, a land 13, and a receiving pad portion 15 extending from the interlayer connection portion 12 (land 13). The end of each signal line 11 is connected to the corresponding interlayer connection portion 12. Each interlayer connection portion 12 has a land 13. The printed circuit board 20, although not shown, has a similar configuration to the printed circuit board 10. This results in a bonded printed circuit board where the multiple signal lines 11 of the printed circuit board 10 and the multiple signal lines 21 of the printed circuit board 20 are electrically connected.

As shown in Figure 13, the multiple signal lines 11 extend parallel to each other along the direction (vertical direction in the figure) connecting the interlayer connection section 12 and the receiving pad section 15. Note that the number of interlayer connection sections 12 is not limited to four and may be increased or decreased according to the required number of signal lines.

As described above, in the bonded printed circuit board 1 of this modified example, each of the multiple signal lines 11 of the printed circuit board 10 is electrically connected to the corresponding signal line 21 among the multiple signal lines 21 via the corresponding receiving pad portion 15, conductive material 30, and receiving pad portion 25 of the printed circuit board 20.

As shown in Figure 13, similar to Modification 1 of the first embodiment, the multiple interlayer connection portions 12 are arranged in a staggered pattern along the width direction (horizontal direction in the figure) of the printed circuit board 10. That is, the multiple interlayer connection portions 12 are arranged such that the line connecting their centers forms a zigzag pattern. This modification allows for a reduction in the width of the multiple interlayer connection portions 12 and a reduction in the area of the connection portion.

Furthermore, multiple interlayer connection sections 12 may be arranged in a staggered pattern along the longitudinal direction (vertical direction in the figure) of the printed circuit board 10.

Furthermore, although Figure 13 shows multiple receiving pad portions 15 extending toward the same side (upper side in the figure), at least one receiving pad portion 15 may extend toward the opposite side (lower side in the figure). For example, the receiving pad portions 15 may alternately extend toward the opposite side along the arrangement direction of the interlayer connection portions 12 (width direction or longitudinal direction of the printed circuit board).

(Modification 2 of the second embodiment)
Referring to Figure 14, a modified example 2 of the second embodiment of the bonded printed circuit board 1 will be described.

As shown in Figure 14, in this modified example, the interlayer connection portion 12 and the receiving pad portion 15 are arranged diagonally. That is, the interlayer connection portion 12 and the receiving pad portion 15 are arranged such that the line connecting the center of the interlayer connection portion 12 and the center of the receiving pad portion 15 intersects diagonally with respect to the width direction of the printed circuit board 10. This allows for a reduction in the width X of multiple interlayer connection portions 12.

Furthermore, the number of interlayer connection sections 12 is not limited to three; it may be increased or decreased according to the required number of signal lines.

(Modification 3 of the second embodiment)
Referring to Figure 15, a modified example 3 of the second embodiment of the bonded printed circuit board 1 will be described.

As shown in Figure 15, in this modified example, the multiple interlayer connection portions 12 and the multiple receiving pad portions 15 are arranged in a straight line along the vertical direction (the longitudinal direction of the printed circuit board 10). This allows the width Y of the multiple interlayer connection portions 12 to be further reduced.

Furthermore, the number of interlayer connection sections 12 is not limited to three; it may be increased or decreased according to the required number of signal lines.

(Modification 4 of the second embodiment)
Referring to Figure 16, a modified example 4 of the second embodiment of the bonded printed circuit board 1 will be described.

As shown in Figure 16, in this modified example, the printed circuit board 10 further includes ground vias 16 electrically connected to the ground layer 17. These ground vias 16 are positioned between the interlayer connection portions 12. This reduces crosstalk between the signal lines 11. Furthermore, it improves the signal transmission characteristics compared to Modification Example 2.

Furthermore, the ground via 16 may be electrically connected to the ground layer 17A. Also, while the ground via 16 is generally different from the ground vias 42 and 52 in Figures 1A and 1B, it may be the same. Additionally, the number of interlayer connections 12 is not limited to three and may be increased or decreased according to the required number of signal lines.

(Modification 5 of the second embodiment)
Referring to Figure 17, a modified example 5 of the second embodiment of the bonded printed circuit board 1 will be described.

In this modified example, as shown in Figure 17, multiple interlayer connection sections 12 are arranged to surround the ground via 16. The ground via 16 is shared by the multiple interlayer connection sections 12. This reduces crosstalk between signal lines and reduces the area of the connection section.

As shown in Figure 17, each of the interlayer connection sections 12 is separated by a separator section S in the ground layer 17. In other words, each interlayer connection section 12 is located in one of the multiple openings provided in the ground layer 17. By providing the separator section S, crosstalk between signal lines can be reduced.

In this modified example, the gap G between the interlayer connection section 12 or receiving pad section 15 and the ground layer 17 is 50 μm, and the width W of the separator section S is 50 μm. The sizes of the gap G and width W may be changed. Furthermore, as shown in Figures 15 and 18, the separator section S may be omitted.

(Modification 6 of the second embodiment)
Referring to Figure 18, a modified example 6 of the second embodiment of the bonded printed circuit board 1 will be described.

As shown in Figure 18, in this modified example, multiple interlayer connecting sections 12 are arranged in a triangular grid. That is, the centers of each interlayer connecting section 12 are located at the vertices of the triangles. The triangles include triangle T1 and equilateral triangle T2.

In this way, by arranging the multiple interlayer connection sections 12 in a triangular grid pattern, it is possible to arrange the multiple interlayer connection sections 12 at a higher density compared to the modified example 1.

As shown in Figure 18, the interlayer connection section 12 has a connecting section (line) 14A that connects the receiving pad section 15 and the interlayer connection section 12. By providing the connecting section 14A, the triangular grid shape can be made into an equilateral triangle, and the width Z of the multiple interlayer connection sections 12 can be further reduced.

This modified example provides a bonded printed circuit board that can accommodate situations requiring four signal lines or two sets of differential lines.

Furthermore, the size (area) of the land 13 and/or receiving pad portion 15 may be changed for each interlayer connection portion 12. For example, in Figure 18, the central receiving pad portion 15 surrounded by the four interlayer connection portions 12 is made smaller than the other receiving pad portions 15. This allows for a higher density arrangement of multiple interlayer connection portions 12 compared to the modified example 1.

(Third embodiment)
Finally, with reference to Figure 19, a bonded printed circuit board 1 according to the third embodiment will be described. Figure 19 is a longitudinal cross-sectional view of the bonded printed circuit board according to the third embodiment along the signal lines 11 and 21.

As shown in Figure 19, unlike the first and second embodiments, in this embodiment, the land extension 14 and land extension 24 are directly electrically connected without the use of a conductive material. The printed circuit board 10 and printed circuit board 20 are joined by a non-conductive material 31. For example, a non-conductive film, non-conductive paste, or adhesive can be used as the non-conductive material 31. Furthermore, the ground layer 17 and ground layer 27 are also directly electrically connected without the use of a conductive material.

Furthermore, direct electrical connections are not limited to land extensions. For example, similar to the modification 2 of the first embodiment, inter-layer connection parts and land extensions may be directly electrically connected, or similar to the combination in the second embodiment, the land extension (receiving pad) and the inter-layer connection part may be directly electrically connected.

As shown in Figure 19, since ground layers 27 and 17 are not provided in the opposing regions A2 and A1 of the interlayer connection sections 12 and 22, this type of connection is possible.

According to this embodiment, conductive material is not required, and the thickness of the joint portion of the bonded printed circuit board 1 can be further reduced compared to the first and second embodiments.

Based on the above description, those skilled in the art may conceive of additional effects and various modifications of the present invention; however, the embodiments of the present invention are not limited to the individual embodiments described above. Components from different embodiments may be combined as appropriate. Various additions, modifications, and partial deletions are permitted without departing from the conceptual idea and spirit of the present invention derived from the claims and their equivalents.

1. Joined printed circuit boards 10, 20; Printed circuit boards 11, 21; Signal lines 12, 22; Interlayer connection sections 13, 23; Lands 14, 24; Land extension section 14A; Connection section (line)
15, 25 Receiving pad portion 16, 26 Ground via 17, 17A, 27, 27A Ground layer 18A, 18B, 28A, 28B Insulating substrate 19, 29 Adhesive layer 30 Conductive material 30a Conductive paste 31 Non-conductive material 41, 51 Ground wire 42, 52 Ground via 100 Single-sided metal foil laminate 110, 210 Insulating substrate 120, 220, 230 Metal foil 130 Adhesive layer 140, 240 Protective film 200 Double-sided metal foil laminate 220a Signal wire 220b Ground wire 300 Printed circuit board 310, 320 Via 330 Plating through hole 410, 420, 430 Opening 410A, 420A, 430A Plating layer A1, A2 Opposing region H1, H2 Via hole H3 Through hole J Joint part S Separation part

Claims (16)

A bonded printed circuit board in which a first printed circuit board and a second printed circuit board are joined together,
The first printed circuit board has a first signal line, a first interlayer connection portion with one end connected to the first signal line, a first land extension portion extending from the other end of the first interlayer connection portion and provided on the bonding surface of the first printed circuit board, and a first ground layer provided on the bonding surface.
The second printed circuit board has a second signal line, a second interlayer connection portion with one end connected to the second signal line, a second land extension portion extending from the other end of the second interlayer connection portion and provided on the bonding surface of the second printed circuit board, and a second ground layer provided on the bonding surface.
The first signal line is electrically connected to the second signal line via the first land extension and the second land extension.
The first interlayer connection portion does not face the second ground layer of the second printed circuit board, and the second interlayer connection portion does not face the first ground layer of the first printed circuit board.
A bonded printed circuit board in which the first interlayer connection portion and the second interlayer connection portion are arranged so as not to face each other, the first land extension portion does not extend to the opposing region of the second interlayer connection portion, the second land extension portion does not extend to the opposing region of the first interlayer connection portion, and the first land extension portion and the second land extension portion are arranged to face each other. The bonded printed circuit board according to claim 1, wherein the first land extension and the second land extension are rectangular in plan view, and the widths of the first land extension and the second land extension are adjusted to match the impedance between the first signal line and the second signal line, respectively. A bonded printed circuit board in which a first printed circuit board and a second printed circuit board are joined together,
The first printed circuit board has a first signal line, a first interlayer connection portion with one end connected to the first signal line, a first land extension portion extending from the other end of the first interlayer connection portion and provided on the bonding surface of the first printed circuit board, and a first ground layer provided on the bonding surface.
The second printed circuit board has a second signal line, a second interlayer connection portion with one end connected to the second signal line, a second land extension portion extending from the other end of the second interlayer connection portion and provided on the bonding surface of the second printed circuit board, and a second ground layer provided on the bonding surface.
The first signal line is electrically connected to the second signal line via the first land extension and the second land extension.
The first interlayer connection portion does not face the second ground layer of the second printed circuit board, and the second interlayer connection portion does not face the first ground layer of the first printed circuit board.
The first interlayer connection portion and the second interlayer connection portion are arranged so as not to face each other in a bonded printed circuit board,
A bonded printed circuit board in which the first land extension extends to the opposing region of the second interlayer connection, and/or the second land extension extends to the opposing region of the first interlayer connection. The bonded printed circuit board according to claim 3, wherein the first land extension portion has a first receiving pad portion facing the second interlayer connection portion, and the second land extension portion has a second receiving pad portion facing the first interlayer connection portion. The bonded printed circuit board according to claim 4 , wherein the first receiving pad portion encompasses the opposing region of the second interlayer connection portion, and the second receiving pad portion encompasses the opposing region of the first interlayer connection portion. A bonded printed circuit board in which a first printed circuit board and a second printed circuit board are joined together,
The first printed circuit board has a first signal line, a first interlayer connection portion with one end connected to the first signal line, a first land extension portion extending from the other end of the first interlayer connection portion and provided on the bonding surface of the first printed circuit board, and a first ground layer provided on the bonding surface.
The second printed circuit board has a second signal line, a second interlayer connection portion with one end connected to the second signal line, a second land extension portion extending from the other end of the second interlayer connection portion and provided on the bonding surface of the second printed circuit board, and a second ground layer provided on the bonding surface.
The first signal line is electrically connected to the second signal line via the first land extension and the second land extension.
The first interlayer connection portion does not face the second ground layer of the second printed circuit board, and the second interlayer connection portion does not face the first ground layer of the first printed circuit board.
The first interlayer connection and/or the first land extension and the second interlayer connection and/or the second land extension are directly electrically connected.
A bonded printed circuit board in which the first printed circuit board and the second printed circuit board are joined by a non-conductive material, the non-conductive material being a non-conductive film, a non-conductive paste , or an adhesive. The bonded printed circuit board according to any one of claims 1 to 6 , wherein the first printed circuit board and/or the second printed circuit board is a flexible printed circuit board. The bonded printed circuit board according to claim 7 , wherein the insulating substrate of the flexible printed circuit board comprises a liquid crystal polymer, a fluorine-based material, or a polyimide-based material. The bonded printed circuit board according to claim 7, wherein the first printed circuit board is connected to an antenna module including an antenna and an antenna substrate, and the second printed circuit board is connected to a main substrate on which a semiconductor chip that performs information processing based on signals received by the antenna is mounted. A bonded printed circuit board in which a first printed circuit board and a second printed circuit board are joined together,
The first printed circuit board has a plurality of first signal lines, a plurality of first interlayer connection portions with one end connected to the plurality of first signal lines, a plurality of first land extension portions extending from the other ends of the plurality of first interlayer connection portions and provided on the bonding surface of the first printed circuit board, and a first ground layer provided on the bonding surface.
The second printed circuit board has a plurality of second signal lines, a plurality of second interlayer connection portions with one end connected to the plurality of second signal lines, a plurality of second land extension portions extending from the other ends of the plurality of second interlayer connection portions and provided on the bonding surface of the second printed circuit board, and a second ground layer provided on the bonding surface.
Each of the plurality of first signal lines is electrically connected to the corresponding second signal line among the plurality of second signal lines via the corresponding first land extension and the second land extension.
The plurality of first interlayer connections do not face the second ground layer of the second printed circuit board, and the plurality of second interlayer connections do not face the first ground layer of the first printed circuit board.
A bonded printed circuit board in which the plurality of first interlayer connection portions are arranged in a staggered pattern along a predetermined direction. A bonded printed circuit board in which a first printed circuit board and a second printed circuit board are joined together,
The first printed circuit board has a plurality of first signal lines, a plurality of first interlayer connection portions with one end connected to the plurality of first signal lines, a plurality of first land extension portions extending from the other ends of the plurality of first interlayer connection portions and provided on the bonding surface of the first printed circuit board, and a first ground layer provided on the bonding surface.
The second printed circuit board has a plurality of second signal lines, a plurality of second interlayer connection portions with one end connected to the plurality of second signal lines, a plurality of second land extension portions extending from the other ends of the plurality of second interlayer connection portions and provided on the bonding surface of the second printed circuit board, and a second ground layer provided on the bonding surface.
Each of the plurality of first signal lines is electrically connected to the corresponding second signal line among the plurality of second signal lines via the corresponding first land extension and the second land extension.
The plurality of first interlayer connections do not face the second ground layer of the second printed circuit board, and the plurality of second interlayer connections do not face the first ground layer of the first printed circuit board.
A bonded printed circuit board in which the first interlayer connection portion and the first land extension portion are arranged such that the line connecting the first interlayer connection portion and the first land extension portion intersects obliquely with respect to the width direction of the first printed circuit board. A bonded printed circuit board in which a first printed circuit board and a second printed circuit board are joined together,
The first printed circuit board has a plurality of first signal lines, a plurality of first interlayer connection portions with one end connected to the plurality of first signal lines, a plurality of first land extension portions extending from the other ends of the plurality of first interlayer connection portions and provided on the bonding surface of the first printed circuit board, and a first ground layer provided on the bonding surface.
The second printed circuit board has a plurality of second signal lines, a plurality of second interlayer connection portions with one end connected to the plurality of second signal lines, a plurality of second land extension portions extending from the other ends of the plurality of second interlayer connection portions and provided on the bonding surface of the second printed circuit board, and a second ground layer provided on the bonding surface.
Each of the plurality of first signal lines is electrically connected to the corresponding second signal line among the plurality of second signal lines via the corresponding first land extension and the second land extension.
The plurality of first interlayer connections do not face the second ground layer of the second printed circuit board, and the plurality of second interlayer connections do not face the first ground layer of the first printed circuit board.
A bonded printed circuit board in which ground vias are arranged between at least one pair of the plurality of first interlayer connection portions. A bonded printed circuit board in which a first printed circuit board and a second printed circuit board are joined together,
The first printed circuit board has a plurality of first signal lines, a plurality of first interlayer connection portions with one end connected to the plurality of first signal lines, a plurality of first land extension portions extending from the other ends of the plurality of first interlayer connection portions and provided on the bonding surface of the first printed circuit board, and a first ground layer provided on the bonding surface.
The second printed circuit board has a plurality of second signal lines, a plurality of second interlayer connection portions with one end connected to the plurality of second signal lines, a plurality of second land extension portions extending from the other ends of the plurality of second interlayer connection portions and provided on the bonding surface of the second printed circuit board, and a second ground layer provided on the bonding surface.
Each of the plurality of first signal lines is electrically connected to the corresponding second signal line among the plurality of second signal lines via the corresponding first land extension and the second land extension.
The plurality of first interlayer connections do not face the second ground layer of the second printed circuit board, and the plurality of second interlayer connections do not face the first ground layer of the first printed circuit board.
A bonded printed circuit board in which ground vias are arranged so as to be surrounded by the plurality of first interlayer connection portions. A bonded printed circuit board in which a first printed circuit board and a second printed circuit board are joined together,
The first printed circuit board has a plurality of first signal lines, a plurality of first interlayer connection portions with one end connected to the plurality of first signal lines, a plurality of first land extension portions extending from the other ends of the plurality of first interlayer connection portions and provided on the bonding surface of the first printed circuit board, and a first ground layer provided on the bonding surface.
The second printed circuit board has a plurality of second signal lines, a plurality of second interlayer connection portions with one end connected to the plurality of second signal lines, a plurality of second land extension portions extending from the other ends of the plurality of second interlayer connection portions and provided on the bonding surface of the second printed circuit board, and a second ground layer provided on the bonding surface.
Each of the plurality of first signal lines is electrically connected to the corresponding second signal line among the plurality of second signal lines via the corresponding first land extension and the second land extension.
The plurality of first interlayer connections do not face the second ground layer of the second printed circuit board, and the plurality of second interlayer connections do not face the first ground layer of the first printed circuit board.
Each of the plurality of first land extensions has a receiving pad portion facing the corresponding second interlayer connection portion.
The plurality of first interlayer connection portions and/or the plurality of receiving pad portions are arranged in a triangular grid pattern in a bonded printed circuit board. The bonded printed circuit board according to claim 14 , wherein at least one of the plurality of first land extensions further has a connecting portion that connects the receiving pad portion and the first interlayer connecting portion. A bonded printed circuit board in which a first printed circuit board and a second printed circuit board are joined together,
The first printed circuit board has a plurality of first signal lines, a plurality of first interlayer connection portions with one end connected to the plurality of first signal lines, a plurality of first land extension portions extending from the other ends of the plurality of first interlayer connection portions and provided on the bonding surface of the first printed circuit board, and a first ground layer provided on the bonding surface.
The second printed circuit board has a plurality of second signal lines, a plurality of second interlayer connection portions with one end connected to the plurality of second signal lines, a plurality of second land extension portions extending from the other ends of the plurality of second interlayer connection portions and provided on the bonding surface of the second printed circuit board, and a second ground layer provided on the bonding surface.
Each of the plurality of first signal lines is electrically connected to the corresponding second signal line among the plurality of second signal lines via the corresponding first land extension and the second land extension.
The plurality of first interlayer connections do not face the second ground layer of the second printed circuit board, and the plurality of second interlayer connections do not face the first ground layer of the first printed circuit board.
A bonded printed circuit board in which each of the plurality of first interlayer connection portions is separated by the first ground layer.