Wiring structure and electronic module

Abstract

This wiring structure comprises a first wiring substrate, a second wiring substrate, and a first connection member that connects the first wiring substrate and the second wiring substrate. The first wiring substrate has a first member, a second member, and a first conductor part. The second wiring substrate has a first insulation layer and a second conductor part. The first insulation layer has a first surface and a second surface. The first member has a first upper surface and a first side surface. The second member has a second upper surface. The first conductor part has a first conductor positioned on the first upper surface and a second conductor positioned on the second upper surface. The second conductor part has a first connection conductor positioned on the second surface and a second connection conductor positioned on the first surface. At least part of the second surface faces the first upper surface and is positioned so as to overlap with the first upper surface in the plan view. The first conductor and the first connection conductor are joined. The first connection member electrically connects the second conductor and the second connection conductor.

Description

Wiring structure and electronic module

[0001] The present disclosure relates to wiring structures and electronic modules.

[0002] A conventional wiring structure is described in, for example, Japanese Patent Application Laid-Open No. 2003-222999.

[0003] Japanese Patent Application Laid-Open No. 2007-5636

[0004] In one embodiment, the (1) wiring structure of the present disclosure includes a first wiring substrate, a second wiring substrate, and a first connection member electrically connecting the first wiring substrate and the second wiring substrate. The first wiring substrate has a first member, a second member connected to the first member, and a first conductor portion. The second wiring substrate has a first insulating layer and a second conductor portion. The second wiring substrate extends from the second member. The first insulating layer has a first surface and a second surface opposite the first surface. The first member has a first upper surface and a first side surface intersecting the first upper surface. The second member has a second upper surface and faces or is located on a surface different from the first side surface of the first member. The first conductor portion has a first conductor located on the first upper surface and a second conductor located on the second upper surface. The second conductor portion has a first connecting conductor located on the second surface and a second connecting conductor located on the first surface. At least a portion of the second surface faces the first upper surface and is positioned overlapping the first upper surface in a plan view. The first conductor and the first connecting conductor are joined. The first connecting member electrically connects the second conductor and the second connecting conductor. (2) In the wiring structure described in (1) above, the first conductor and the first connecting conductor are ground conductors. (3) In the wiring structure described in (1) or (2) above, the second conductor and the second connecting conductor are signal conductors or ground conductors. (4) The wiring structure described in (1) or (2) above further includes a second connecting member electrically connecting the first wiring board and the second wiring board. The first conductor portion further includes a third conductor positioned on the second upper surface and spaced apart from the second conductor. The second conductor portion further includes a third connecting conductor positioned on the first surface and spaced apart from the second connecting conductor. The second connecting member electrically connects the third conductor and the third connecting conductor. The first conductor and the first connecting conductor are ground conductors. The second conductor and the second connecting conductor are ground conductors. The third conductor and the third connecting conductor are signal conductors. (5) In the wiring structure described in (1) to (4) above, the first connecting conductor and the second connecting conductor are electrically connected within the second wiring substrate. (6) In the wiring structure described in (1) to (5) above, the second member has a first upper surface and a second side surface intersecting the second upper surface. Furthermore, the first upper surface is lower than the second upper surface.(7) In the wiring structure described in (6) above, in a cross-sectional view perpendicular to the first top surface, the distance L1 from the first top surface to the second top surface is equal to or greater than the distance L2 from the first top surface to the first surface. (8) In the wiring structure described in (6) or (7) above, the second wiring substrate contacts the second side surface. (9) In the wiring structure described in (1) to (8) above, the second member has a second side surface intersecting the first top surface and the second top surface. The second side surface has a first cutout portion and a first conductor layer provided in the first cutout portion. The surface of the second wiring substrate facing the second side surface has a second cutout portion and a second conductor layer provided in the second cutout portion. The first conductor layer and the second conductor layer are bonded by a bonding material. (10) In the wiring structure described in (1) to (9) above, the second member has a first upper surface and a second side surface intersecting the second upper surface. The first upper surface is lower than the second upper surface. The first conductor portion has a side conductor connecting the first conductor and the second conductor. The side conductor is located on the second side surface. (11) In the wiring structure described in (1) to (10) above, the first connecting member is a wire. (12) In the wiring structure described in (11) above, the first connecting member is covered with an insulating material. (13) In the wiring structure described in (1) to (12) above, the second wiring board is a flexible wiring board. (14) The wiring structure described in (1) to (13) above further includes a third wiring board electrically connected to the second wiring board. (15) The wiring structure described in (1) to (14) above further includes a box body that houses electronic components. The first wiring board is part of the box body. At least a portion of the first member and the second member is exposed to the outside of the box. In one embodiment (16), an electronic module includes the wiring structure described in any one of (1) to (14) above, and an electronic component electrically connected to the first conductor portion. In one embodiment (17), an electronic module includes the wiring structure described in (15) above, an electronic component housed in a box, and a lid located on the box.

[0005] 1 is a perspective view of a wiring structure and an electronic module according to an embodiment; FIG. 2 is a perspective view showing a first wiring substrate of a wiring structure according to an embodiment; FIG. 3 is a perspective view of a wiring structure according to an embodiment, viewed from below; FIG. 4 is an enlarged view of a main portion IV of the wiring structure shown in FIG. 1; FIG. 5 is a view of the wiring structure shown in FIG. 4 cut along V-V; FIG. 6 is a view of the wiring structure shown in FIG. 4 cut along VI-VI; FIG. 7 is a cross-sectional view showing an example of a wiring structure having a fourth wiring substrate; FIG. 8 is a perspective view showing an example of a wiring structure having a fourth wiring substrate; FIG. 9 is a cross-sectional view showing an example of a wiring structure having a fourth wiring substrate; FIG. 10 is an enlarged view showing a first notch portion, a first conductor layer, a second notch portion, and a second conductor layer; FIG. 11 is a graph showing the reflection characteristics of a wiring structure according to an embodiment and a wiring structure according to a comparative example; FIG. 12 is a graph showing the transmission characteristics of a wiring structure according to an embodiment and a wiring structure according to a comparative example.

[0006] <Configuration of Wiring Structure> Several exemplary embodiments will be described below with reference to the drawings. Note that although either direction of the wiring structure may be considered to be up or down, for convenience, a Cartesian coordinate system xyz is defined, and the positive side of the z direction is considered to be up. In addition, in this disclosure, a plan view is a concept that includes a planar perspective view.

[0007] As shown in FIGS. 1 to 6, the wiring structure includes a first wiring substrate 1, a second wiring substrate 2, and a first connecting member 41 that electrically connects the first wiring substrate 1 and the second wiring substrate 2.

[0008] The first wiring board 1 has a first member 11 , a second member 12 connected to the first member 11 , and a first conductor portion 10 .

[0009] The first member 11 has a first upper surface 11u and a first side surface 11s intersecting the first upper surface 11u. The first member 11 may also have a first lower surface 11b opposite the first upper surface 11u. The material of the first member 11 is an insulating material, and may be, for example, an aluminum oxide sintered body, a mullite sintered body, a silicon carbide sintered body, an aluminum nitride sintered body, a silicon nitride sintered body, or a ceramic material such as glass ceramics.

[0010] The material of the first member 11 may be a resin material. The resin material may be one selected from the group consisting of epoxy resin, phenolic resin, unsaturated polyester resin, polytetrafluoroethylene resin, urea resin, melamine resin, and thermosetting polyimide resin. The material of the first member 11 may be a metal material. Examples of the metal material include copper, iron, tungsten, molybdenum, nickel, and cobalt, as well as alloys containing these metal materials.

[0011] The second member 12 has a second upper surface 12u and faces or is located on a surface different from the first side surface 11s of the first member 11. In the embodiment shown in FIG. 2 , the second member 12 is located on the opposite side of the first member 11 from the first side surface 11s in the x direction. However, as a modified example, the second member 12 may face or be located on a side surface of the first member 11 in the y direction. The second member 12 may also have a second lower surface 12b opposite the second upper surface 12u. The material of the second member 12 may be the same as or different from that of the first member 11. When the material of the first member 11 and the material of the second member 12 are the same, the first member 11 and the second member 12 may be molded integrally. In particular, when the material of the second member 12 is a ceramic material, wiring can be easily positioned inside the second member 12.

[0012] When the material of the first member 11 and the material of the second member 12 are different, the first member 11 and the second member 12 may be joined with a conductive adhesive (e.g., silver epoxy resin). In this case, the wiring formed on the second member 12 and the first conductor 111 (described later) formed on the first member 11 may be electrically connected by the conductive adhesive. In addition, in this case, the first member 11 and the second member 12 do not need to be in contact with each other without a gap, and there may be a partial gap between the first member 11 and the second member 12.

[0013] Wiring may be located on the inner layer of the first member 11 and / or the second member 12 .

[0014] The first conductor 10 includes a first conductor 111 located on the first upper surface 11u of the first member 11 and a second conductor 122 located on the second upper surface 12u of the second member 12. Examples of materials for the first conductor 10 include metal materials such as gold, silver, copper, nickel, tungsten, molybdenum, and manganese. The first conductor 10 may be formed by sintering a metal paste on the first member 11 and / or the second member 12, or by using a thin-film formation technique such as a vapor deposition method or a sputtering method. The first conductor 10 may have a plating layer on its surface. When the first member 11 is made of a metal material, the first conductor 111 (described later) may be formed solely by plating.

[0015] As shown in Fig. 2 , in one embodiment, the first conductor 111 is positioned so as to cover the entire first upper surface 11u, but this is not necessarily required. For example, the first conductor 111 may be partially interrupted, or there may be multiple first conductors 111. Also, Fig. 2 illustrates the first conductor 111 as a ground conductor. However, there may be multiple first conductors 111 on the first upper surface 11u, and they may serve as signal conductors and / or ground conductors and have the same shape as the second conductor 122 and / or third conductor 123 located on the second upper surface 12u.

[0016] The second wiring board 2 has a first insulating layer 21 and a second conductor portion 20. The second wiring board 2 extends from the second member 12. The second wiring board 2 may be flexible, for example, a so-called flexible printed circuit (FPC) or a printed circuit board (PCB) on which an electronic circuit is formed. When the second wiring board 2 is a flexible wiring board, the second wiring board 2 can be easily handled, improving design freedom. When the second wiring board 2 is a flexible wiring board, the material of the first insulating layer 21 is a resin material.

[0017] The second wiring board 2 may be further bonded to the first side surface 11s with an insulating adhesive, thereby reducing the possibility that the second wiring board 2 will shift or fall off from the first wiring board 1.

[0018] An insulating film may be located on a portion of the second conductor portion 20 of the second wiring board 2. More specifically, an insulating film may be located on the second conductor portion 20 in a portion other than the portion where the second wiring board 2 and the first wiring board 1 overlap in a planar view and / or the portion where the second wiring board 2 and a third wiring board 3 (described below) overlap in a planar view. This configuration can reduce the possibility of the second conductor portion 20 being damaged or corroded. An example of the insulating film is a coverlay.

[0019] The first insulating layer 21 of the second wiring board 2 has a first surface 21u and a second surface 21b opposite the first surface 21u. At least a portion of the second surface 21b faces the first upper surface 11u of the first wiring board 1 and overlaps the first upper surface 11u in a plan view. In other words, the second wiring board 2 at least partially overlaps the first wiring board 1. The material of the first insulating layer 21 may be, for example, a resin. The dielectric constant of the first insulating layer 21 may be lower than the dielectric constant of the first member 11 and / or the dielectric constant of the second member 12.

[0020] 1 , 3 , 4 , 5 , and 6 , the second conductor portion 20 of the second wiring board 2 has a first connecting conductor 211 located on the second surface 21 b and a second connecting conductor 212 located on the first surface 21 u. Examples of materials for the second conductor portion 20 include metal materials. The second conductor portion 20 may be in contact with or spaced from the end face of the first insulating layer 21.

[0021] 5, the first conductor 111 of the first wiring board 1 is joined to the first connecting conductor 211 of the second wiring board 2. The first conductor 111 and the first connecting conductor 211 may be joined to each other by a bonding material 21J such as solder or conductive resin.

[0022] The first connecting member 41 electrically connects the second conductor 122 of the first wiring board 1 and the second connecting conductor 212 of the second wiring board 2. This configuration allows the first conductor portion 10 and the second conductor portion 20 to be designed more finely than when the first wiring board 1 and the second wiring board 2 are electrically connected without using the first connecting member 41. This allows the number of first conductor portions 10 and second conductor portions 20 serving as electrodes to be increased, thereby enabling higher density and integration of the wiring. Furthermore, when the second conductor 122 and the second connecting conductor 212 are used as signal conductors, the resulting wiring structure is suitable for transmitting high-frequency signals.

[0023] 5 and 6, in one embodiment, the first conductor 111 and the first connecting conductor 211 may be ground conductors, which can increase the area of ​​the ground conductor and strengthen the ground potential.

[0024] The second conductor 122 and the second connecting conductor 212 may be signal conductors or ground conductors. When the first conductor 111 and the first connecting conductor 211 are ground conductors, the second conductor 122 and the second connecting conductor 212 may be signal conductors. With this configuration, the first conductor portion 10 and the second conductor portion 20 can have a coplanar structure, and signal transmission in the second conductor 122 and the second connecting conductor 212 can be stabilized. In the embodiments shown in FIGS. 1 to 6, the second conductor 122 and the second connecting conductor 212 are described as ground conductors.

[0025] The first connecting conductor 211 of the second wiring board 2 may cover 70% or more of the area of ​​the second surface 21b. With this configuration, the area of ​​the first connecting conductor 211 as a grounding conductor can be increased, and the ground potential on the second wiring board 2 can be strengthened.

[0026] 4 , in one embodiment, the wiring structure may further include a second connection member 42 electrically connecting the first wiring board 1 and the second wiring board 2. The first conductor portion 10 may further include a third conductor 123 located on the second upper surface 12u of the second member 12 and spaced apart from the second conductor 122. The second conductor portion 20 may further include a third connection conductor 213 located on the first surface 21u and spaced apart from the second connection conductor 212. The second connection member 42 electrically connects the third conductor 123 and the third connection conductor 213. The first conductor 111 and the first connection conductor 211 may be ground conductors, the second conductor 122 and the second connection conductor 212 may be ground conductors, and the third conductor 123 and the third connection conductor 213 may be signal conductors. As described above, since the first conductor portion 10 can be designed finely, the dimensions of the third conductor 123 and the third connecting conductor 213 can be reduced, particularly in the y direction. Therefore, with the above configuration, it is easy to adjust the impedance of the third conductor 123 and the third connecting conductor 213. This makes it possible to provide a wiring structure suitable for transmitting high-frequency signals. Furthermore, the number of third conductors 123 and third connecting conductors 213 can be increased, allowing more signal channels to be formed in the wiring structure.

[0027] 2 and 4 , the dimension of the third conductor 123 in the y direction may be such that it increases as it approaches the second side surface 12s. In other words, the width of the third conductor 123 may be such that it increases as it approaches the second side surface 12s. With this configuration, the second connecting member 42 can be stably joined. Furthermore, multiple second connecting members 42 can be connected. Similarly, the dimension of the third conductor portion 30 in the y direction may be such that it increases as it approaches the end face of the second wiring board 2 facing the second side surface 12s.

[0028] The width of each conductor in the first conductor section 10 and the second conductor section 20 (the dimension in the y direction in the drawing) can be adjusted and designed to be larger or smaller to adjust the impedance depending on the frequency of the signal flowing through the conductor.

[0029] The second conductor 122 may be in contact with or spaced from the second side surface 12s in plan view. Similarly, the third conductor 123 may be in contact with or spaced from the second side surface 12s in plan view. If the third conductor 123 is in contact with the second side surface 12s in plan view, the second connecting member 42 can be shortened, thereby reducing the possibility of impedance fluctuations between the third conductor 123 serving as a signal conductor and the third connecting conductor 213.

[0030] The second connecting conductor 212 may be in contact with or spaced from the end face of the second wiring board 2 on the second member 12 side in a plan view. Similarly, the third connecting conductor 213 may be in contact with or spaced from the end face of the second wiring board 2 on the second member 12 side in a plan view. If the third connecting conductor 213 is in contact with the end face of the second wiring board 2 on the second member 12 side in a plan view, the second connecting member 42 can be shortened, thereby reducing the possibility of impedance fluctuations between the third conductor 123 serving as a signal conductor and the third connecting conductor 213. Furthermore, if the third connecting conductor 213 is spaced from the end face of the second wiring board 2 on the second member 12 side in a plan view, the possibility of the first connecting conductor 211 and the third connecting conductor 213 connecting to each other and causing a short circuit can be reduced even if the bonding material 21J bonding the first conductor 111 and the first connecting conductor 211 creeps up from the second surface 21b side to the first surface 21u side.

[0031] When there are a plurality of third conductors 123, the pair of third conductors 123 may function as a differential signal line that transmits a differential signal. In this case, the pair of third conductors 123 may be positioned sandwiched between a plurality of second conductors 122 that serve as grounding conductors. When the pair of third conductors 123 is a differential signal line, there may also be a plurality of third connecting conductors 213, and the pair of third connecting conductors 213 may also function as a differential signal line that transmits a differential signal.

[0032] Furthermore, as shown in FIG. 4 , the first conductor portion 10 may include a fourth conductor 124. The fourth conductor 124 does not have to be connected to the second conductor portion 20 by the first connecting member 41 and / or the second connecting member 42. The fourth conductor 124 may also be located between a pair of third conductors 123 serving as signal conductors. This configuration strengthens the ground potential in the first conductor portion 10. This reduces the possibility of resonance occurring in the pair of third conductors 123. The fourth conductor 124 may be in contact with or separated from the second side surface 12s in a plan view. When the first conductor portion 10 includes the fourth conductor 124, the second wiring board 2 may include a conductor electrically connected to the fourth conductor 124.

[0033] 2 and 6 , the first upper surface 11u may have a first conductor 111 as a grounding conductor and a first exposed region 110 where the first upper surface 11u is exposed. The first exposed region 110 may be located, at least in a plan view, overlapping the position where the first connecting member 41 and / or the second connecting member 42 are connected to the second conductor portion 20 of the second wiring board 2. This configuration allows the first conductor 111 to be spaced apart below the connection position between the first connecting member 41 and / or the second connecting member 42 and the second conductor portion 20. This reduces the possibility of a large capacitance component occurring at the connection position between the first connecting member 41 and / or the second connecting member 42 and the second conductor portion 20.

[0034] Furthermore, the first exposed region 110 may be in contact with or separated from the second side surface 12s. In the embodiment shown in Fig. 2, the first conductor 111 has the first exposed region 110 between the portions connected to the side conductors 114, but as a modified example, the shape of the first exposed region 110 may be a strip extending in the y direction. The position, size, and shape of the first exposed region 110 can be determined appropriately depending on the connection positions of the first connecting member 41 and / or the second connecting member 42 and the second conductor portion 20.

[0035] 3 and 6 , the second surface 21b of the second wiring board 2 may have a first connecting conductor 211 serving as a grounding conductor and a second exposed region 210 where the second surface 21b is exposed. The second exposed region 210 may be located, at least in a plan view, overlapping the position where the first connecting member 41 and / or the second connecting member 42 are connected to the second conductor portion 20 of the second wiring board 2. This configuration allows the first connecting conductor 211 to be spaced apart below the connection position between the first connecting member 41 and / or the second connecting member 42 and the second conductor portion 20. This reduces the possibility of a large capacitance component occurring at the connection position between the first connecting member 41 and / or the second connecting member 42 and the second conductor portion 20.

[0036] Furthermore, the second exposed region 210 may be in contact with or separated from the end face of the second wiring substrate 2. In the embodiment shown in Fig. 3, the first connection conductor 211 has the partially interrupted second exposed region 210, but as a modified example, the shape of the second exposed region 210 may be a strip extending in the y direction along the end face of the first insulating layer 21. The position, size, and shape of the second exposed region 210 can be determined appropriately depending on the connection position between the first connection member 41 and / or the second connection member 42 and the second conductor portion 20.

[0037] In a plan view, the first exposed region 110 and the second exposed region 210 may at least partially overlap. With this configuration, the first connecting conductor 211 can be located farther below the connection position between the first connecting member 41 and / or the second connecting member 42 and the second conductor portion 20 than when the first exposed region 110 and the second exposed region 210 do not overlap. This makes it possible to more efficiently reduce the possibility of the capacitance component becoming large at the connection position between the first connecting member 41 and / or the second connecting member 42 and the second conductor portion 20.

[0038] As shown in FIGS. 1, 2, and 4, the second member 12 may have a recess 120 located at least on the second upper surface 12u. The recess 120 may be located, for example, between the plurality of third conductors 123 and / or between the second conductor 122 and the third conductor 123. The recess 120 is filled with at least one dielectric material, such as air, a resin material, or a glass material, and has a lower dielectric constant than the second member 12. This reduces the capacitance between the second conductor 122 and the third conductor 123 and / or between the plurality of third conductors 123. This allows the characteristic impedance of the third conductor 123 to be adjusted to a desired value when transmitting a high-frequency signal. This reduces the signal power loss that occurs in the first conductor portion 10.

[0039] The first connecting conductor 211 and the second connecting conductor 212 may be electrically connected within the second wiring board 2. More specifically, as shown in FIG. 5 , the first connecting conductor 211 and the second connecting conductor 212 may be connected by a via conductor 21V. For example, if the first connecting conductor 211 and the second connecting conductor 212 are grounding conductors, the ground potential can be strengthened. If the first connecting conductor 211 and the second connecting conductor 212 are signal conductors, the signals flowing through the first connecting conductor 211 and the second connecting conductor 212 can be merged and the signals can be amplified. If the first connecting conductor 211 and the second connecting conductor 212 are power supply conductors, a large drive current can be passed through them.

[0040] As shown in FIG. 5 , the via conductor 21V connecting the first connecting conductor 211 and the second connecting conductor 212 may be a so-called blind via. In other words, the via conductor 21V connecting the first connecting conductor 211 and the second connecting conductor 212 does not have to be a through-hole via. This configuration reduces the possibility that the bonding material 21J will flow out toward the first surface 21u and short-circuit with the third connecting conductor 213. Furthermore, the first connecting member 41 is bonded to the surface of the second connecting conductor 212. When bonding the first connecting member 41 to the second connecting conductor 212, the bonding material 21J can reduce the possibility that the flatness of the surface of the second connecting conductor 212 will be reduced. It is not necessary for all via conductors 21V in the second wiring board 2 to be blind vias. For example, blind vias may be provided only at positions where the second wiring board 2 and the first wiring board 1 overlap.

[0041] The first upper surface 11u and the second upper surface 12u may be flush. This configuration allows the height (dimension in the z direction) of the first wiring substrate 1 to be reduced. When the first upper surface 11u and the second upper surface 12u are different in height, the first upper surface 11u and the second upper surface 12u do not need to be perfectly parallel. For example, this may include a case where the first upper surface 11u is inclined toward the positive direction of the x-axis, a case where the first upper surface 11u is inclined toward the positive or negative direction of the x-axis, or a case where the first upper surface 11u is inclined toward the positive or negative direction of the y-axis.

[0042] As shown in FIGS. 2 and 6 , the second member 12 may have a second side surface 12s that intersects with the first upper surface 11u and the second upper surface 12u. Furthermore, the first upper surface 11u may be lower than the second upper surface 12u. With this configuration, when the second wiring board 2 is located on the first upper surface 11u, the heights of the first conductor portion 10 and the second conductor portion 20 can be made closer, thereby minimizing the length of the first connecting member 41 and / or the second connecting member 42. This reduces the possibility of impedance fluctuations at the electrical connection between the first wiring board 1 and the second wiring board 2. Furthermore, when the second wiring board 2 is located on the first upper surface 11u, the second wiring board 2 can be easily positioned.

[0043] The second wiring board 2 may be in contact with the second side surface 12s. This makes it easier to position the second wiring board 2 when placing the second wiring board 2 on the first upper surface 11u. It also reduces the possibility that the second wiring board 2 will be displaced from its predetermined position on the first upper surface 11u. The second wiring board 2 does not have to be in contact with the second side surface 12s. If the second wiring board 2 is not in contact with the second side surface 12s, it reduces the possibility that the second wiring board 2 will come into contact with the second side surface 12s and be damaged.

[0044] 6 , in a cross-sectional view perpendicular to first upper surface 11u, distance L1 from first upper surface 11u to second upper surface 12u may be equal to or greater than distance L2 from first upper surface 11u of first wiring board 1 to first surface 21u of second wiring board 2. When distance L1 from first upper surface 11u to second upper surface 12u is equal to distance L2 from first upper surface 11u of first wiring board 1 to first surface 21u of second wiring board 2, the length of second connection member 42 can be made as short as possible by adjusting the thicknesses of third conductor 123 and third connecting conductor 213, thereby reducing the possibility of fluctuations in the impedance value at the electrical connection portion between first wiring board 1 and second wiring board 2.

[0045] When the second member 12 has a second side surface 12s that intersects with the first top surface 11u and the second top surface 12u, and the first top surface 11u is lower than the second top surface 12u, the first conductor portion 10 may have a side conductor 114 that connects the first conductor 111 and the second conductor 122, as shown in Fig. 2. The side conductor 114 is located on the second side surface 12s. With this configuration, when the first conductor 111 and the second conductor 122 are grounding conductors, the ground potential can be strengthened.

[0046] Furthermore, as shown in FIG. 2, the dimension of the side conductor 114 in the y direction may be smaller than the dimension of the second conductor 122 in the y direction.

[0047] When the first member 11 and the second member 12 are integral, the first conductor 111 may be located so as to extend into the second conductor 122. In this case, the first conductor 111 and the second conductor 122 may be electrically connected by a via formed in the second member 12.

[0048] The first connection member 41 may be a wire or a ribbon wire. The number of first connection members 41 connecting the second conductor 122 and the second connection conductor 212 is not limited to one, and may be two or more as shown in Fig. 4. The second connection member 42 may also be a wire or a ribbon wire, and there may be more than one second connection member 42 as shown in Fig. 4. In one embodiment, the electrical connection state between the first connection member 41 and / or the second connection member 42 of the first wiring board 1 and the second wiring board 2 can be referred to as wire bonding or ribbon bonding.

[0049] As shown in Figure 4, the first connection members 41 that connect two second conductors 122 positioned on either side of a pair of third conductors 123 and two second connection conductors 212 positioned on either side of a pair of third connection conductors 213 may have a spacing that increases toward the second wiring board 2 side (i.e., in the positive direction of the x-axis in the drawing).

[0050] When the pair of third conductors 123 and the pair of third connecting conductors 213 are connected by the second connecting members 42, the distance between the second connecting members 42 may increase toward the second wiring board 2 (i.e., in the positive direction of the x-axis in the drawings). This reduces the possibility of abrupt impedance fluctuations when a signal is transmitted between the pair of third conductors 123 and the pair of third connecting conductors 213, and reduces the possibility of unwanted electrical signals being reflected by the pair of third conductors 123 and the pair of third connecting conductors 213.

[0051] The first connection member 41 may be covered with an insulating material. The second connection member 42 may also be covered with an insulating material. With this configuration, the first connection member 41 and / or the second connection member 42 can be protected from external impact, thereby reducing the possibility that the first connection member 41 and / or the second connection member 42 will fall off and the electrical connection between the first wiring board 1 and the second wiring board 2 will be interrupted.

[0052] 1 , the wiring structure may further include a third wiring board 3 electrically connected to the second wiring board 2. The third wiring board 3 may be a printed circuit board on which an electronic circuit is formed. More specifically, it is sufficient that the third conductor 30 located on the third wiring board 3 is electrically connected to the second conductor 20 of the second wiring board 2.

[0053] Furthermore, the second wiring board 2 may further include a fourth connecting conductor 214 located on the second surface 21 b at a position where the second wiring board 2 and the third wiring board 3 overlap. The fourth connecting conductor 214 may be electrically connected to the third connecting conductor 213, and may serve as a signal conductor together with the third connecting conductor 213.

[0054] The third connecting conductor 213 and the fourth connecting conductor 214 may be electrically connected by a via located in the second wiring board 2. In this case, the connection between the third connecting conductor 213 and the fourth connecting conductor 214 does not have to be by a blind via.

[0055] The electrical connection between the second wiring board 2 and the third wiring board 3 may include not only the joining between the fourth connecting conductor 214 and the third conductor portion 30 but also a connection by a wire, similar to the electrical connection between the second wiring board 2 and the first wiring board 1. Furthermore, the connecting member such as the wire connecting the second wiring board 2 and the third wiring board 3 may be covered with an insulating material.

[0056] 1 , the wiring structure may further include a box body 5 that houses electronic components 6. In this case, the first wiring board 1 may be part of the box body 5, and at least a part of the first member 11 and the second member 12 may be exposed to the outside of the box body 5.

[0057] The box 5 may have at least a plate 51 located on the second lower surface 12b of the second member 12, and a frame 52 joined to the plate 51 and / or the first wiring board 1. Electronic components 6, which will be described later, can be accommodated in the space formed by the plate 51, the frame 52, and the first wiring board 1.

[0058] Examples of materials for the plate 51 include metal materials such as copper, iron, tungsten, molybdenum, nickel, and cobalt, as well as alloys containing these metal materials. In this case, the plate 51 may be a single metal plate or a laminate of multiple metal plates. Furthermore, if the metal material constituting the plate 51 is one of the above metal materials, a plating layer of nickel, gold, or the like may be formed on the surface of the plate 51 using electroplating or electroless plating to reduce oxidation corrosion. Note that the plate 51 being made of a metal material here means that it is essentially made of a metal material. For example, the plate 51 may contain a non-metallic material that is unavoidable during manufacturing. The plate 51 may also be made of a high-heat-dissipating material using a carbon material such as graphite.

[0059] The material of the frame 52 may be the same as or different from the material of the plate 51 and / or the second member 12. The frame 52 may have a light-transmitting portion 520 that penetrates the box 5 from the inside to the outside. The light-transmitting portion 520 serves as a window for transmitting and receiving light between the inside and outside of the box 5.

[0060] Furthermore, the first wiring board 1 may have a third member 13 located on the second member 12. The second member 12 and the third member 13 may be integral and made of an insulating material. In this case, the material of the second member 12 and the third member 13 may be a ceramic material.

[0061] <Modification> The first member 11 has a first lower surface 11b on the side opposite the first upper surface 11u. The second member 12 has a second lower surface 12b on the side opposite the second upper surface 12u. In the embodiment shown in FIG. 3, the first lower surface 11b and the second lower surface 12b are flush with each other. However, for example, the second lower surface 12b may protrude in the negative direction of the z-axis beyond the first lower surface 11b. Conductors similar to the first conductor portion 10 formed on the first upper surface 11u and the second upper surface 12u may also be located on the first lower surface 11b and the second lower surface 12b. In this case, a fourth wiring substrate 70, which is a wiring substrate different from the second wiring substrate 2 described above, may be attached to the conductors formed on the first lower surface 11b and the second lower surface 12b. In this case, the electrical connection between the first wiring substrate 1 and the fourth wiring substrate 70 may include a connection via a third connecting member 72. The third connecting member may be, for example, a wire.

[0062] The fourth wiring board 70 may be flexible, and may be, for example, a so-called flexible wiring board (FPC), or a printed circuit board (PCB) on which an electronic circuit is formed.

[0063] 7 , a fourth wiring substrate 70 may be additionally connected to the first lower surface 11 b of the first member 11. With this configuration, the wiring structure can exchange even more electrical signals. In this case, the electrical connection between the first wiring substrate 1 and the fourth wiring substrate 70 may include a connection via a third connecting member 72.

[0064] 8 and 9, the first wiring board 1 may further have a protruding portion 16 that protrudes from the first side surface 11s in the positive direction of the x-axis. A fourth wiring board 70 may be additionally connected to the protruding portion 16.

[0065] 9, the protruding portion 16 may have a stepped shape. Furthermore, as shown in FIG. 9, when a fourth wiring board 70 is located on the protruding portion 16, the fourth wiring board 70 may be electrically connected to the conductor located on the protruding portion 16 by a third connecting member 72.

[0066] 7 to 9, the second wiring substrate 2 and the fourth wiring substrate 70 may be bonded to each other via the first side surface 11s with an insulating adhesive 71 such as resin. This improves the bonding strength between the first wiring substrate 1, the second wiring substrate 2, and the fourth wiring substrate 70. As shown in FIG. 9, the adhesive 71 may cover the third bonding member.

[0067] Furthermore, when the first upper surface 11u is located lower than the second upper surface 12u, the first wiring substrate 1 may have a plurality of structures that form the first upper surface 11u and the second upper surface 12u. That is, as shown in FIG. 2, the first wiring substrate 1 has a step formed from the first upper surface 11u to the second upper surface 12u, but there may be a plurality of such steps.

[0068] 7, the second wiring board 2 may be bonded to the first side surface 11s of the first wiring board 1, or may be bonded to the first lower surface 11b of the first wiring board 1 by extending the adhesive from the first side surface 11s to the first lower surface 11b. In this case, the second wiring board 2 may be bonded to the first lower surface 11b by an insulating adhesive 71 such as a resin.

[0069] 10 , a notch may be provided on each of the second side surface 12s of the second member 12 in the first wiring board 1 and the surface of the second wiring board 2 facing the second side surface 12s, a conductor layer may be provided on the side surface of the notch, and the conductor layers may be bonded together with a bonding material such as solder. That is, when the second side surface 12s has a first notch 14 and a first conductor layer 15 provided in the first notch 14, and the surface of the second wiring board 2 facing the second side surface 12s has a second notch 24 and a second conductor layer 25 provided in the second notch 24, the first conductor layer 15 and the second conductor layer 25 may be bonded together with a bonding material.

[0070] The first cutout portion 14 and the first conductor layer 15 can form, for example, a castellation, and the second cutout portion 24 and the second conductor layer 25 can also form, for example, a castellation.

[0071] In this case, when the first conductor layer 15 provided in the first cutout portion 14 is connected to the conductor of the first conductor portion 10 of the first wiring board 1 (at least one of the first conductor 111 and the second conductor 122) and the second conductor layer 25 provided in the second cutout portion 24 is connected to the connection conductor of the second conductor portion 20 of the second wiring board 2 (at least one of the first connection conductor 211 and the second connection conductor 212), the conductor of the first conductor portion 10 and the connection conductor of the second conductor portion 20 can be electrically connected firmly. For example, if the conductor of the first conductor portion 10 connected to the first conductor layer 15 and the connection conductor of the second conductor portion 20 connected to the second conductor layer 25 are both ground conductors, connecting them via the first conductor layer 15 and the second conductor layer 25 can strengthen the ground potential.

[0072] The number of first notches 14 on the second side surface 12s and the number of second notches 24 on the surface of the second wiring board 2 facing the second side surface 12s may be the same, or each may be any number greater than or equal to one.

[0073] 10 shows an example in which the first conductor layer 15 is connected to the second conductor 122 and the second conductor layer 25 is connected to the second connecting conductor 212, and the first connecting member 41 is omitted. The connection between the conductor of the first conductor section 10 of the first wiring board 1 and the first conductor layer 15 and the connection between the connecting conductor of the second conductor section 20 of the second wiring board 2 and the second conductor layer 25 are not limited to the example shown in FIG. 10 . As described above, the first conductor layer 15 may be connected to the first conductor 111, and the second conductor layer 25 may be connected to the first connecting conductor 211.

[0074] <Simulation Results> FIG. 11 is a graph showing the reflection characteristics of the wiring structure shown in FIGS. 1 to 6 , with the horizontal axis representing the frequency (GHz) of the input signal and the vertical axis representing the reflection characteristic (dB). In the graph showing the reflection characteristics, the smaller the reflection characteristic (dB), the smaller the signal reflection. The solid line represents the characteristics of the wiring structure according to an embodiment of the present disclosure. Meanwhile, the dashed line represents the characteristics of the wiring structure according to the comparative example. In the wiring structure according to the comparative example, the first member 11 and the first connecting member 41 are removed from the wiring structure according to the present disclosure, and the second wiring substrate 2 is joined to the second conductor 122 and the third conductor 123. Referring to FIG. 11 , it can be seen that the wiring structure according to the present disclosure exhibits better reflection characteristics than the comparative example.

[0075] 1 to 6, the horizontal axis represents the frequency (GHz) of the input signal, and the vertical axis represents the pass characteristic (dB). In the graph showing the pass characteristic, the larger the pass characteristic (dB) value, the smaller the signal loss. The solid line represents the characteristics of the wiring structure according to an embodiment of the present disclosure. Meanwhile, the dashed line represents the characteristics of the wiring structure according to the comparative example. Referring to FIG. 12, it can be seen that the wiring structure according to the present disclosure exhibits better pass characteristic than the comparative example.

[0076] <Configuration of Electronic Module> In one embodiment, the electronic module may include a wiring structure and an electronic component 6 electrically connected to the first conductor 10. The electronic component 6 does not necessarily have to be covered by a lid, which will be described later.

[0077] In one embodiment, the electronic module may include a wiring structure, electronic components 6 housed in a box 5 , and a lid positioned on the box 5 .

[0078] The lid is positioned on the box 5 to cover the inside of the box 5 and protects the electronic components 6 together with the box 5 .

[0079] Examples of the electronic component 6 include optical semiconductor elements such as semiconductor lasers (LD: Laser Diode) or photodiodes (PD: Photodiode), semiconductor integrated circuit elements such as field effect transistors (FET: Field Effect Transistor), and sensor elements such as optical sensors. The electronic component 6 can be formed from a semiconductor material such as gallium arsenide or gallium nitride. The number of electronic components 6 included in the electronic module is not limited to one, and may be multiple, or may be of multiple types. In this case, the electronic component 6 may be, for example, an amplifier or a capacitor.

[0080] The electronic module may further include a seal ring located between the lid and the frame 52. The seal ring functions to join the lid and the frame 52 together.

[0081] In one embodiment, the electronic module can be used as a transceiver for optical communications.

[0082] It should be noted that various combinations of the embodiments and modifications are not limited to the examples of the embodiments described above, and combinations of the embodiments and / or modifications can also be made.

[0083] The present disclosure can be used in wiring structures and electronic modules.

[0084] REFERENCE SIGNS LIST 1 First wiring board 10 First conductor portion 11 First member 11u First upper surface 11b First lower surface 11s First side surface 110 First exposed area 111 First conductor 114 Side surface conductor 12 Second member 12u Second upper surface 12b Second lower surface 12s Second side surface 120 Recess 122 Second conductor 123 Third conductor 124 Fourth conductor 13 Third member 14 First notch portion 15 First conductor layer 16 Protrusion 2 Second wiring board 20 Second conductor portion 21 First insulating layer 21u First surface 21b Second surface 210 Second exposed area 211 First connecting conductor 212 Second connecting conductor 213 Third connecting conductor 214 Fourth connecting conductor 21V Via conductor 21J Bonding material 24 Second notch portion 25 Second conductor layer 3 Third wiring board 30 Third conductor portion 41 First connecting member 42 Second connecting member 5 Box body 51 Plate body 52 Frame body 520 Light-transmitting portion 6 Electronic component 70 Fourth wiring board 71 Adhesive 72 Third connecting member

Claims

1. A first wiring board having a first member, a second member connected to the first member, and a first conductor portion; a second wiring board having a first insulating layer and a second conductor portion; and a first connection member electrically connecting the first wiring board and the second wiring board, wherein the second wiring board extends from the second member, the first insulating layer has a first surface and a second surface opposite the first surface, the first member has a first upper surface and a first side surface intersecting the first upper surface, the second member has a second upper surface and faces or is located on a surface different from the first side surface of the first member, the first conductor portion has a first conductor located on the first upper surface and a second conductor located on the second upper surface, and the second conductor portion has a first connecting conductor located on the second surface and a second connecting conductor located on the first surface, A wiring structure, wherein at least a portion of the second surface faces the first upper surface and is positioned overlapping the first upper surface in a planar view, the first conductor and the first connecting conductor are joined, and the first connecting member electrically connects the second conductor and the second connecting conductor.

2. The wiring structure of claim 1, wherein the first conductor and the first connecting conductor are ground conductors.

3. The wiring structure according to claim 1 or 2, wherein the second conductor and the second connecting conductor are signal conductors or ground conductors.

4. A wiring structure as claimed in any one of claims 1 to 3, further comprising a second connecting member electrically connecting the first wiring board and the second wiring board, the first conductor portion further having a third conductor located on the second upper surface and spaced from the second conductor, the second conductor portion further having a third connecting conductor located on the first surface and spaced from the second connecting conductor, the second connecting member electrically connecting the third conductor and the third connecting conductor, the first conductor and the first connecting conductor are grounding conductors, the second conductor and the second connecting conductor are grounding conductors, and the third conductor and the third connecting conductor are signal conductors.

5. A wiring structure according to any one of claims 1 to 4, wherein the first connecting conductor and the second connecting conductor are electrically connected within the second wiring board.

6. A wiring structure as claimed in any one of claims 1 to 5, wherein the second member has a second side surface intersecting the first upper surface and the second upper surface, and the first upper surface is lower than the second upper surface.

7. The wiring structure of claim 6, wherein in a cross-sectional view perpendicular to the first upper surface, a distance L1 from the first upper surface to the second upper surface is greater than or equal to a distance L2 from the first upper surface to the first surface.

8. The wiring structure according to claim 6 or 7, wherein the second wiring board is in contact with the second side surface.

9. A wiring structure as described in any one of claims 1 to 8, wherein the second member has a second side surface intersecting the first top surface and the second top surface, the second side surface having a first cutout portion and a first conductor layer provided in the first cutout portion, a surface of the second wiring board facing the second side surface has a second cutout portion and a second conductor layer provided in the second cutout portion, and the first conductor layer and the second conductor layer are joined by a bonding material.

10. A wiring structure as described in any one of claims 1 to 9, wherein the second member has a second side surface intersecting the first top surface and the second top surface, the first top surface is lower than the second top surface, the first conductor portion has a side conductor electrically connecting the first conductor and the second conductor, and the side conductor is located on the second side surface.

11. The wiring structure according to any one of claims 1 to 10, wherein the first connection member is a wire.

12. The wiring structure of claim 11, wherein the first connection member is covered with an insulating material.

13. The wiring structure according to any one of claims 1 to 12, wherein the second wiring board is a flexible wiring board.

14. The wiring structure according to any one of claims 1 to 13, further comprising a third wiring board electrically connected to the second wiring board.

15. A wiring structure as described in any one of claims 1 to 14, further comprising a box body for housing electronic components, the first wiring board being part of the box body, and at least a portion of the first member and the second member being exposed to the outside of the box body.

16. An electronic module comprising: a wiring structure according to any one of claims 1 to 14; and an electronic component electrically connected to the first conductor portion.

17. An electronic module comprising: the wiring structure according to claim 15; an electronic component housed in said box; and a lid located on said box.

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