Multilayer substrate, method for manufacturing multilayer substrate, and electronic device

Abstract

The first conductor layer is connected to the first interlayer connection conductor and the second interlayer connection conductor. The first conductor layer has the same composition as the first interlayer connection conductor and the second interlayer connection conductor. One or more first metal foil layers are connected to the third main surface of the first conductor layer. One or more first metal foil layers overlap the first interlayer connection conductor and the second interlayer connection conductor when viewed in the first direction. One or more second metal foil layers overlap the first interlayer connection conductor and the second interlayer connection conductor when viewed in the first direction and are electrically connected to the first interlayer connection conductor and the second interlayer connection conductor. The one or more second metal foil layers have a different composition than the first conductor layer.

Description

Technical Field

[0001] The present invention relates to a multilayer substrate having a structure in which multiple insulating layers are stacked. Background Technology

[0002] As a prior art invention related to multilayer substrates, for example, a multilayer substrate as described in Patent Document 1 is known. This multilayer substrate includes a laminate, a first ground conductor, a second ground conductor, a first interlayer connection conductor, and a second interlayer connection conductor. The laminate has a structure in which multiple insulating substrates are stacked in a vertical direction. The first ground conductor is disposed on the upper main surface of the insulating substrate. The second ground conductor is disposed on the lower main surface of the insulating substrate. The first and second interlayer connection conductors penetrate the insulating substrate in a vertical direction. The upper ends of the first and second interlayer connection conductors are connected to the first ground conductor. The lower ends of the first and second interlayer connection conductors are connected to the second ground conductor.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-127228 ( Figure 12 ) Summary of the Invention

[0006] The problem the invention aims to solve

[0007] However, in the multilayer substrate described in Patent Document 1, there is a desire to suppress the poor connection between the first interlayer connection conductor and the first ground conductor, the first interlayer connection conductor and the second ground conductor, the second interlayer connection conductor and the first ground conductor, and the second interlayer connection conductor and the second ground conductor.

[0008] Therefore, the object of the present invention is to provide a multilayer substrate, a method for manufacturing the multilayer substrate, and an electronic device capable of suppressing poor electrical connections between multiple interlayer connecting conductors and one or more first metal foil layers and between multiple interlayer connecting conductors and one or more second metal foil layers.

[0009] means for solving problems

[0010] One aspect of the multilayer substrate of the present invention comprises:

[0011] A laminate having a configuration in which multiple insulating layers are stacked and arranged along a first direction, the multiple insulating layers including a first insulating layer having a first main surface and a second main surface, the first main surface being located closer to the first direction than the second main surface;

[0012] Multiple interlayer connecting conductors penetrate the first insulating layer along the first direction, and include a first interlayer connecting conductor and a second interlayer connecting conductor;

[0013] A first conductor layer is connected to the first main surface of the first insulator layer, and to the first interlayer connecting conductor and the second interlayer connecting conductor, and has a third main surface and a fourth main surface, wherein the third main surface is located closer to the first direction than the fourth main surface, and the composition of the first conductor layer is the same as the composition of the first interlayer connecting conductor and the second interlayer connecting conductor.

[0014] One or more first metal foil layers are connected to the third main surface of the first conductor layer, and the one or more first metal foil layers overlap with the first interlayer connecting conductor and the second interlayer connecting conductor when viewed along the first direction; the composition of the one or more first metal foil layers is different from the composition of the first conductor layer; and

[0015] One or more second metal foil layers are located in a second direction of the first insulating layer, the second direction being the opposite direction to the first direction. When viewed along the first direction, the one or more second metal foil layers overlap with the first interlayer connecting conductor and the second interlayer connecting conductor, and are electrically connected to the first interlayer connecting conductor and the second interlayer connecting conductor. The composition of the one or more second metal foil layers is different from that of the first conductor layer.

[0016] In a method for manufacturing a multilayer substrate according to one aspect of the present invention, the multilayer substrate includes a laminate having a configuration in which multiple insulating layers, including a third insulating layer, a first insulating layer, and a second insulating layer, are stacked and arranged sequentially along a first direction. The third insulating layer has a ninth and a tenth main surface, the first insulating layer has a first and a second main surface, and the second insulating layer has a seventh and an eighth main surface.

[0017] The first main surface is located in the first direction, which is closer to the second main surface.

[0018] The seventh principal plane is located in the first direction closer to the eighth principal plane.

[0019] The ninth principal plane is located in the first direction closer to the tenth principal plane.

[0020] The method for manufacturing the multilayer substrate includes:

[0021] The first preparation step is to prepare the first insulating layer having a first through hole and a second through hole.

[0022] The second preparation step involves preparing the second insulating layer on the eighth main surface, to which the first metal foil layer is disposed;

[0023] The third preparation step is to prepare the third insulating layer on the ninth main surface where the second metal foil layer is provided;

[0024] The coating process, following the second preparation process, involves applying a conductive paste or metal grease onto the first metal foil layer; and

[0025] In the lamination process, after the coating process, the third insulating layer, the first insulating layer, and the second insulating layer are stacked, and the conductive paste or the metal paste is filled into the first through hole and the second through hole, and the conductive paste or the metal paste overflows from the first through hole and the second through hole, thereby forming the conductive paste or the metal paste in the first through hole and the conductive paste or the metal paste in contact with the conductive paste or the metal paste in the first through hole onto the first metal foil layer.

[0026] Invention Effects

[0027] According to the multilayer substrate of the present invention, it is possible to suppress poor electrical connections between multiple interlayer connecting conductors and one or more first metal foil layers, as well as between multiple interlayer connecting conductors and one or more second metal foil layers. Attached Figure Description

[0028] Figure 1 This is an exploded perspective view of the multilayer substrate 10.

[0029] Figure 2 yes Figure 1 A cross-sectional view at point AA.

[0030] Figure 3 yes Figure 1 A cross-sectional view at BB.

[0031] Figure 4 This is a diagram showing a portion of an electronic device 100.

[0032] Figure 5 This is a cross-sectional view of the multilayer substrate 10 during manufacturing.

[0033] Figure 6 This is a cross-sectional view of the multilayer substrate 10a.

[0034] Figure 7 This is a cross-sectional view of the multilayer substrate 10b.

[0035] Figure 8 This is a cross-sectional view of the multilayer substrate 10c.

[0036] Figure 9 This is a top view of the insulating layer 15a of the multilayer substrate 10d.

[0037] Figure 10 This is a top view of the insulating layer 15a of the multilayer substrate 10e.

[0038] Figure 11 This is a top-view view of the multilayer substrate 10f.

[0039] Figure 12 This is a bottom view of the insulating layer 15a of the multilayer substrate 10g.

[0040] Figure 13 This is a cross-sectional view of the insulating layer 15a of the multilayer substrate 10h, orthogonal to the vertical direction. Detailed Implementation

[0041] (Implementation Method)

[0042] [Structure of multilayer substrates]

[0043] Hereinafter, the structure of the multilayer substrate 10 according to an embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 This is an exploded perspective view of the multilayer substrate 10. It should be noted that... Figure 1 In the diagram, only representative interlayer connection conductors v7 within the multiple interlayer connection conductors v7 are marked with reference labels. Figure 2 yes Figure 1 A cross-sectional view at point AA. Figure 3 yes Figure 1 A cross-sectional view at BB. Figure 4 This is a diagram showing a portion of an electronic device 100.

[0044] In this specification, directions are defined as follows: The direction in which the multiple insulating layers 14a-14e, 15a, and 15b are arranged is defined as the up-down direction. The up or down direction is the first direction. The second direction is the opposite of the first direction. Therefore, when the up direction is the first direction, the down direction is the second direction. When the down direction is the first direction, the up direction is the second direction. The direction in which the first signal conductor layer 20 extends is defined as the left-right direction. The left-right direction is orthogonal to the up-down direction. The direction orthogonal to both the left-right and up-down directions is defined as the front-back direction. It should be noted that the up-down, front-back, and left-right directions in this embodiment may not be consistent with the up-down, front-back, and left-right directions when using the multilayer substrate 10.

[0045] Hereinafter, X refers to a component or part of the multilayer substrate 10. In this specification, unless otherwise specified, the various parts of X are defined as follows: Front part of X refers to the front half of X. Rear part of X refers to the rear half of X. Left part of X refers to the left half of X. Right part of X refers to the right half of X. Upper part of X refers to the upper half of X. Lower part of X refers to the lower half of X. Front end of X refers to the end of X in the forward direction. Rear end of X refers to the end of X in the rear direction. Left end of X refers to the end of X in the left direction. Right end of X refers to the end of X in the right direction. Upper end of X refers to the end of X in the upward direction. Lower end of X refers to the end of X in the downward direction. Front end of X refers to the front end of X and its vicinity. Rear end of X refers to the rear end of X and its vicinity. Left end of X refers to the left end of X and its vicinity. Right end of X refers to the right end of X and its vicinity. Upper end of X refers to the upper end of X and its vicinity. Lower end of X refers to the lower end of X and its vicinity.

[0046] First, refer to Figure 1 The structure of the multilayer substrate 10 will be described. The multilayer substrate 10 transmits high-frequency signals. The multilayer substrate 10 is used in electronic devices such as smartphones to electrically connect two circuits. For example... Figure 1 As shown, the multilayer substrate 10 includes a laminate 12, a protective layer 16, a first signal conductor layer 20, a reference conductor layer 22 (second metal foil layer), a reference conductor layer 24 (second metal foil layer), a reference conductor layer 26a (first metal foil layer), a reference conductor layer 26b (first metal foil layer), first conductor layers 28b, 28c, second conductor layers 28a, 28d, signal terminals 40, 50, reference terminals 42, 44, 52, 54, interlayer connection conductors v1 to v6, and a plurality of interlayer connection conductors v7.

[0047] The laminate 12 has an insulating layer 14a-14e, 15a, 15b (multiple insulating layers) stacked in a vertical direction (first direction). In this embodiment, the multiple insulating layers 14a, 14b, 15a, 14c, 14d, 15b, 14e are arranged sequentially from top to bottom. Insulating layers 14a-14e each have an upper main surface and a lower main surface. Insulating layers 14a-14e each have a rectangular shape when viewed in the vertical direction. The long sides of insulating layers 14a-14e extend in the horizontal direction.

[0048] Insulator layer 15a has an upper main surface (second main surface) and a lower main surface (first main surface). In insulating layer 15a, the lower main surface (first main surface) is located below (in a first direction) the upper main surface (second main surface). Insulator layer 15b has an upper main surface (first main surface) and a lower main surface (second main surface). In insulating layer 15b, the upper main surface (first main surface) is located above (in a first direction) the lower main surface (second main surface). Insulator layers 15a and 15b have rectangular shapes when viewed along the vertical direction. The long sides of insulating layers 15a and 15b extend along the horizontal direction.

[0049] Insulating layers 14a-14e, 15a, and 15b contain thermoplastic resins. Examples of thermoplastic resins include liquid crystal polymers and PTFE (polytetrafluoroethylene). Insulating layers 14a-14e, 15a, and 15b may also contain polyimide.

[0050] like Figure 1 and Figure 2 As shown, the first conductor layer 28b is in contact with the lower main surface (first main surface) of the insulating layer 15a (first insulating layer). The first conductor layer 28b has an upper main surface (fourth main surface) and a lower main surface (third main surface). In the first conductor layer 28b, the lower main surface (third main surface) is located below (in the first direction) the upper main surface (fourth main surface). The first conductor layer 28b has a rectangular ring shape when viewed in the downward direction (first direction). More specifically, the first conductor layer 28b extends along the two long sides and two short sides of the insulating layer 15a when viewed in the vertical direction.

[0051] The second conductor layer 28a is in contact with the upper main surface (second main surface) of the insulating layer 15a (first insulating layer). The second conductor layer 28a has an upper main surface (sixth main surface) and a lower main surface (fifth main surface). In the second conductor layer 28a, the lower main surface (fifth main surface) is located below (in the first direction) the upper main surface (sixth main surface). The second conductor layer 28a has the same shape as the first conductor layer 28b when viewed in the vertical direction. The second conductor layer 28a has a rectangular ring shape when viewed in the vertical direction. More specifically, the second conductor layer 28a extends along the two long sides and two short sides of the insulating layer 15a when viewed in the vertical direction. In addition, the entire outer edge of the second conductor layer 28a overlaps the entire outer edge of the first conductor layer 28b when viewed in the vertical direction. The entire inner edge of the second conductor layer 28a overlaps the entire inner edge of the first conductor layer 28b when viewed in the vertical direction.

[0052] Reference conductor layer 26a is located on the upper main surface of insulator layer 14c. Furthermore, first conductor layer 28b is located above reference conductor layer 26a. Thus, reference conductor layer 26a (first metal foil layer) is in contact with the lower main surface (third main surface) of first conductor layer 28b. Reference conductor layer 26a has a rectangular ring shape when viewed vertically. More specifically, reference conductor layer 26a extends along the two long sides and two short sides of insulator layer 14c when viewed vertically. However, the outer edge of reference conductor layer 26a is located slightly outside the outer edge of first conductor layer 28b when viewed vertically. The inner edge of reference conductor layer 26a is located slightly inside the inner edge of first conductor layer 28b when viewed vertically.

[0053] The reference conductor layer 22 is located on the lower main surface of the insulator layer 14b. Therefore, the reference conductor layer 22 is located above the insulator layer 15a (the first insulator layer) (in the second direction). That is, the reference conductor layer 22 (the second metal foil layer) is located above the insulator layer 15a (the first insulator layer) (in the second direction). Furthermore, the second conductor layer 28a is located below the reference conductor layer 22. Therefore, the reference conductor layer 22 (the second metal foil layer) is in contact with the upper main surface (the sixth main surface) of the second conductor layer 28a. The reference conductor layer 22 has a rectangular shape when viewed in the vertical direction. More specifically, the reference conductor layer 22 covers approximately the entire lower main surface of the insulator layer 14b when viewed in the vertical direction. However, an opening is provided in the reference conductor layer 22 at the position where it overlaps with the interlayer connecting conductors v1 and v2 when viewed in the vertical direction, so that the reference conductor layer 22 does not contact the interlayer connecting conductors v1 and v2 described later.

[0054] The first conductor layer 28c, the second conductor layer 28d, and the reference conductor layers 24 and 26b have a structure that is vertically symmetrical with respect to the first conductor layer 28b, the second conductor layer 28a, and the reference conductor layers 22 and 26a. More specifically, the first conductor layer 28c is in contact with the upper main surface (first main surface) of the insulating layer 15b (first insulating layer). The first conductor layer 28c has an upper main surface (third main surface) and a lower main surface (fourth main surface). In the first conductor layer 28c, the upper main surface (third main surface) is located above (in the first direction) the lower main surface (fourth main surface). The first conductor layer 28c has a rectangular ring shape when viewed in the vertical direction (first direction). More specifically, the first conductor layer 28c extends along the two long sides and two short sides of the insulating layer 14e when viewed in the vertical direction.

[0055] The second conductor layer 28d is in contact with the lower main surface (second main surface) of the insulating layer 15b (first insulating layer). The second conductor layer 28d has an upper main surface (fifth main surface) and a lower main surface (sixth main surface). In the second conductor layer 28d, the upper main surface (fifth main surface) is located above (in the first direction) the lower main surface (sixth main surface). The second conductor layer 28d has the same shape as the first conductor layer 28c when viewed in the vertical direction. The second conductor layer 28d has a rectangular ring shape when viewed in the vertical direction (first direction). More specifically, the second conductor layer 28d extends along the two long sides and two short sides of the insulating layer 15b when viewed in the vertical direction. In addition, the entire outer edge of the second conductor layer 28d overlaps the entire outer edge of the first conductor layer 28c when viewed in the vertical direction. The entire inner edge of the second conductor layer 28d overlaps the entire inner edge of the first conductor layer 28c when viewed in the vertical direction.

[0056] The reference conductor layer 26b is located on the lower main surface of the insulator layer 14d. Furthermore, the first conductor layer 28c is located below the reference conductor layer 26b. Thus, the reference conductor layer 26b (the first metal foil layer) is in contact with the upper main surface (the third main surface) of the first conductor layer 28c. The reference conductor layer 26b has a rectangular ring shape when viewed vertically. More specifically, the reference conductor layer 26b extends along the two long sides and two short sides of the insulator layer 14d when viewed vertically. However, the outer edge of the reference conductor layer 26b is located slightly outside the outer edge of the first conductor layer 28c when viewed vertically. The inner edge of the reference conductor layer 26b is located slightly inside the inner edge of the first conductor layer 28c when viewed vertically.

[0057] Reference conductor layer 24 is located on the upper main surface of insulator layer 14e. Furthermore, second conductor layer 28d is located above reference conductor layer 24. Thus, reference conductor layer 24 (second metal foil layer) is in contact with the lower main surface (sixth main surface) of second conductor layer 28d. Reference conductor layer 24 has a rectangular shape when viewed vertically. More specifically, reference conductor layer 24 covers approximately the entire upper main surface of insulator layer 14e when viewed vertically. The aforementioned reference conductor layers 22, 24, 26a, and 26b are connected to a reference potential, such as ground potential.

[0058] like Figure 1 and Figure 2As shown, multiple interlayer connecting conductors v7 penetrate the insulating layers 15a, 14c, 14d, and 15b along the vertical direction (first direction). When viewed along the vertical direction, the multiple interlayer connecting conductors v7 are arranged along the first conductor layers 28b and 28c and the second conductor layers 28a and 28d. Furthermore, the multiple interlayer connecting conductors v7 are connected to reference conductor layers 22, 24, 26a, 26b, the first conductor layers 28b and 28c, and the second conductor layers 28a and 28d.

[0059] like Figure 3 As shown, the multiple interlayer connecting conductors v7 include multiple interlayer connecting conductors v7a and multiple interlayer connecting conductors v7b. The multiple interlayer connecting conductors v7a and multiple interlayer connecting conductors v7b are arranged alternately. Figure 3 In this diagram, only representative interlayer connecting conductors v7a and v7b within the plurality of interlayer connecting conductors v7a and v7b are marked with reference numerals. Interlayer connecting conductors v7a and v7b are adjacent. Therefore, there are no other conductors between interlayer connecting conductors v7a and v7b. In this embodiment, interlayer connecting conductor v7b is the interlayer connecting conductor closest to interlayer connecting conductor v7a.

[0060] Interlayer connecting conductor v7a includes interlayer connecting conductors v11 to v14. Interlayer connecting conductors v11 to v14 are circular when viewed vertically. Interlayer connecting conductors v11 to v14 are arranged in a row from top to bottom. Interlayer connecting conductor v11 (the first interlayer connecting conductor) penetrates the insulating layer 15a (the first insulating layer) in the downward direction (first direction). Interlayer connecting conductor v11 is connected to the second conductor layer 28a and the first conductor layer 28b. The diameter of the lower end of interlayer connecting conductor v11 is larger than the diameter of the upper end of interlayer connecting conductor v11. Interlayer connecting conductor v12 penetrates the insulating layer 14c in the downward direction. Interlayer connecting conductor v12 is connected to the reference conductor layer 26a. The diameter of the lower end of interlayer connecting conductor v12 is larger than the diameter of the upper end of interlayer connecting conductor v12. Interlayer connecting conductor v13 penetrates the insulating layer 14d in the upward direction. Interlayer connecting conductor v13 is connected to interlayer connecting conductor v12 and reference conductor layer 26b. The diameter of the upper end of interlayer connecting conductor v13 is larger than the diameter of the lower end of interlayer connecting conductor v13. Interlayer connecting conductor v14 (first interlayer connecting conductor) penetrates the insulating layer 15b (first insulating layer) in the upward direction (first direction). Interlayer connecting conductor v14 is connected to the first conductor layer 28c and the second conductor layer 28d. The diameter of the upper end of interlayer connecting conductor v14 is larger than the diameter of the lower end of interlayer connecting conductor v14.

[0061] Here, since interlayer connecting conductor v7a and interlayer connecting conductor v7b are adjacent, interlayer connecting conductor v11 (first interlayer connecting conductor) and interlayer connecting conductor v21 (second interlayer connecting conductor) are adjacent. In this embodiment, interlayer connecting conductor v21 (second interlayer connecting conductor) is the interlayer connecting conductor closest to interlayer connecting conductor v11 (first interlayer connecting conductor).

[0062] Interlayer connecting conductor v7b includes interlayer connecting conductors v21 to v24. Interlayer connecting conductors v21 to v24 are circular when viewed vertically. Interlayer connecting conductors v21 to v24 are arranged in a row from top to bottom. Interlayer connecting conductor v21 (the second interlayer connecting conductor) penetrates the insulating layer 15a (the first insulating layer) in the downward direction (first direction). Interlayer connecting conductor v21 is connected to the second conductor layer 28a and the first conductor layer 28b. The diameter of the lower end of interlayer connecting conductor v21 is larger than the diameter of the upper end of interlayer connecting conductor v21. Interlayer connecting conductor v22 penetrates the insulating layer 14c in the downward direction. Interlayer connecting conductor v22 is connected to the reference conductor layer 26a. The diameter of the lower end of interlayer connecting conductor v22 is larger than the diameter of the upper end of interlayer connecting conductor v22. Interlayer connecting conductor v23 penetrates the insulating layer 14d in the upward direction. Interlayer connecting conductor v23 is connected to interlayer connecting conductor v22 and reference conductor layer 26b. The diameter of the upper end of interlayer connecting conductor v23 is larger than the diameter of the lower end of interlayer connecting conductor v23. Interlayer connecting conductor v24 (first interlayer connecting conductor) penetrates the insulator layer 15b (first insulator layer) in the upward direction (first direction). Interlayer connecting conductor v24 is connected to the first conductor layer 28c and the second conductor layer 28d. The diameter of the upper end of interlayer connecting conductor v24 is larger than the diameter of the lower end of interlayer connecting conductor v24.

[0063] Here, since interlayer connecting conductor v7a and interlayer connecting conductor v7b are adjacent, interlayer connecting conductor v14 (first interlayer connecting conductor) and interlayer connecting conductor v24 (second interlayer connecting conductor) are adjacent. In this embodiment, interlayer connecting conductor v24 (second interlayer connecting conductor) is the interlayer connecting conductor closest to interlayer connecting conductor v14 (first interlayer connecting conductor).

[0064] Because the interlayer connecting conductors v7a and v7b have the above-described structure, the reference conductor layer 26a (first metal foil layer), reference conductor layer 22 (second metal foil layer), first conductor layer 28b, and second conductor layer 28a overlap with the interlayer connecting conductors v11 (first interlayer connecting conductor) and v21 (second interlayer connecting conductor) when viewed in the downward direction (first direction). In this embodiment, the reference conductor layer 26a (first metal foil layer), reference conductor layer 22 (second metal foil layer), first conductor layer 28b, and second conductor layer 28a overlap with the interlayer connecting conductors v11 (first interlayer connecting conductor) and v21 (second interlayer connecting conductor) when viewed in the downward direction (first direction).

[0065] The second conductor layer 28a is connected to the interlayer connecting conductor v11 (first interlayer connecting conductor) and the interlayer connecting conductor v21 (second interlayer connecting conductor). The reference conductor layer 22 is connected to the second conductor layer 28a. Therefore, the reference conductor layer 22 (second metal foil layer) is electrically connected to the interlayer connecting conductor v11 (first interlayer connecting conductor) and the interlayer connecting conductor v21 (second interlayer connecting conductor) via the second conductor layer 28a.

[0066] Furthermore, the first conductor layer 28b is connected to the interlayer connecting conductor v11 (first interlayer connecting conductor) and the interlayer connecting conductor v21 (second interlayer connecting conductor). The reference conductor layer 26a is connected to the first conductor layer 28b. Therefore, the reference conductor layer 26a is electrically connected to the interlayer connecting conductor v11 (first interlayer connecting conductor) and the interlayer connecting conductor v21 (second interlayer connecting conductor) via the first conductor layer 28b.

[0067] Furthermore, when viewed in the upward direction (first direction), reference conductor layer 26b (first metal foil layer), reference conductor layer 24 (second metal foil layer), first conductor layer 28c, and second conductor layer 28d overlap with interlayer connecting conductor v14 (first interlayer connecting conductor) and interlayer connecting conductor v24 (second interlayer connecting conductor). In this embodiment, when viewed in the upward direction (first direction), reference conductor layer 26b (first metal foil layer), reference conductor layer 24 (second metal foil layer), first conductor layer 28c, and second conductor layer 28d overlap with interlayer connecting conductor v14 (first interlayer connecting conductor) and interlayer connecting conductor v24 (second interlayer connecting conductor).

[0068] The first conductor layer 28c is connected to the interlayer connecting conductor v14 (first interlayer connecting conductor) and the interlayer connecting conductor v24 (second interlayer connecting conductor). The reference conductor layer 26b is connected to the first conductor layer 28c. Therefore, the reference conductor layer 26b (first metal foil layer) is electrically connected to the interlayer connecting conductor v14 (first interlayer connecting conductor) and the interlayer connecting conductor v24 (second interlayer connecting conductor) via the first conductor layer 28c.

[0069] Furthermore, the second conductor layer 28d is connected to the interlayer connecting conductor v14 (first interlayer connecting conductor) and the interlayer connecting conductor v24 (second interlayer connecting conductor). The reference conductor layer 24 is connected to the second conductor layer 28d. Therefore, the reference conductor layer 24 is electrically connected to the interlayer connecting conductor v14 (first interlayer connecting conductor) and the interlayer connecting conductor v24 (second interlayer connecting conductor) via the second conductor layer 28d.

[0070] Interlayer conductors v11-v14 and v21-v24, as described above, are formed by filling the through-holes in insulating layers 14c, 15a, and 15b with conductive paste and then curing the conductive paste by heating. Alternatively, first conductor layers 28b and 28c and second conductor layers 28a and 28d are formed by applying conductive paste to the upper or lower main surfaces of reference conductor layers 22, 26a, 26b, and 24 and then curing the conductive paste by heating. Thus, the compositions of the first conductor layers 28b and 28c and the second conductor layers 28a and 28d are the same as the compositions of interlayer conductors v11 and v14 (first interlayer conductors) and interlayer conductors v21 and v24 (second interlayer conductors). The conductive paste comprises resin and metal powder. The metal powder is, for example, an alloy powder of Sn and Cu. As described above, interlayer connecting conductors v11, v14 (first interlayer connecting conductors) and interlayer connecting conductors v21, v24 (second interlayer connecting conductors) comprise resin and metal. It should be noted that, in this specification, "same composition" means "including the same alloy containing multiple metals." Specifically, for example, it includes alloys containing Sn and other metals, such as SnAgCu.

[0071] Furthermore, reference conductor layers 22, 24, 26a, and 26b are formed, for example, by etching a metal foil disposed on the upper or lower main surface of insulating layers 14b, 14c, 14d, and 14e. The metal foil is, for example, copper foil. The compositions of reference conductor layers 26a and 26b (first metal foil layers) and reference conductor layers 22 and 24 (second metal foil layers) differ from the compositions of first conductor layers 28b and 28c and second conductor layers 28a and 28d.

[0072] A first high-frequency signal is transmitted in the first signal conductor layer 20. The first high-frequency signal is, for example, a digital signal. Figure 1 As shown, the first signal conductor layer 20 is located on the upper main surface of the insulating layer 14c. The first signal conductor layer 20 has a linear shape when viewed in the vertical direction. The first signal conductor layer 20 extends in the horizontal direction. Furthermore, the first signal conductor layer 20 is surrounded by a first conductor layer 28b when viewed in the vertical direction (first direction). Thus, the first conductor layer 28b surrounds the first signal conductor layer 20, which is a circuit element that radiates noise, when viewed in the vertical direction (first direction).

[0073] Furthermore, reference conductor layer 22 is located above the first signal conductor layer 20. Reference conductor layer 24 is located below the first signal conductor layer 20. Thus, the first signal conductor layer 20 and reference conductor layers 22 and 24 have a stripline structure.

[0074] Here, as Figure 2 and Figure 3 As shown, the plane passing through the center of the insulating layer 15a in the vertical direction is defined as plane S1. At this time, the distance D1 between the interlayer connection conductor v11 (first interlayer connection conductor) and the interlayer connection conductor v21 (second interlayer connection conductor) is defined as follows: and the distance D2 between the interlayer connection conductor v11 (first interlayer connection conductor) and the first signal conductor layer 20 is defined as follows.

[0075] • The shortest distance between the cross-section of interlayer connecting conductor v11 (first interlayer connecting conductor) in plane S1 and the cross-section of interlayer connecting conductor v21 (second interlayer connecting conductor) in plane S1 is defined as distance D1.

[0076] • The shortest distance between the cross section of the interlayer connecting conductor v11 (first interlayer connecting conductor) on plane S1 when viewed in the vertical direction and the first signal conductor layer 20 is defined as distance D2.

[0077] At this time, the distance D1 between the interlayer connecting conductor v11 (first interlayer connecting conductor) and the interlayer connecting conductor v21 (second interlayer connecting conductor) is shorter than the distance D2 between the interlayer connecting conductor v11 (first interlayer connecting conductor) and the first signal conductor layer 20.

[0078] Signal terminal 40 and reference terminals 42 and 44 are located at the left end of the upper main surface of insulating layer 14a. Signal terminal 40 and reference terminals 42 and 44 have a rectangular shape when viewed vertically. Reference terminals 42, 40, and 44 are arranged sequentially from front to back. The first signal conductor layer 20, signal terminals 40, and reference terminals 42 and 44 are formed, for example, by etching a metal foil disposed on the upper main surface of insulating layers 14a and 14c. The metal foil is, for example, copper foil.

[0079] like Figure 1As shown, interlayer connecting conductor v1 penetrates the insulating layers 14a, 14b, and 15a in the vertical direction. Interlayer connecting conductor v1 connects the signal terminal 40 to the left end of the first signal conductor layer 20. Interlayer connecting conductors v3 and v4 penetrate the insulating layers 14a and 14b in the vertical direction. Interlayer connecting conductor v3 connects the reference terminal 42 to the reference conductor layer 22. Interlayer connecting conductor v4 connects the reference terminal 44 to the reference conductor layer 22. The interlayer connecting conductors v1, v3, and v4 are formed by filling the through holes provided in the insulating layers 14a, 14b, and 15a with conductive paste and then curing the conductive paste by heating. It should be noted that the signal terminals 50, reference terminals 52 and 54, and interlayer connecting conductors v2, v5, and v6 have a structure that is symmetrical to the signal terminals 40, reference terminals 42 and 44, and interlayer connecting conductors v1, v3, and v4, therefore, the description is omitted.

[0080] The protective layer 16 covers approximately the entire upper surface of the insulating layer 14a. However, openings ha to hf are provided in the protective layer 16. Signal terminal 40 is exposed to the outside of the multilayer substrate 10 through opening ha. Reference terminal 42 is exposed to the outside of the multilayer substrate 10 through opening hb. Reference terminal 44 is exposed to the outside of the multilayer substrate 10 through opening hc. Signal terminal 50 is exposed to the outside of the multilayer substrate 10 through opening hd. Reference terminal 52 is exposed to the outside of the multilayer substrate 10 through opening he. Reference terminal 54 is exposed to the outside of the multilayer substrate 10 through opening hf.

[0081] The multilayer substrate 10 described above is used in electronic devices 100 such as smartphones. For example... Figure 4 As shown, the electronic device includes a multilayer substrate 10 and a housing 102. The housing 102 houses the multilayer substrate 10.

[0082] like Figure 4 As shown, the multilayer substrate 10 is bent for use. More specifically, the multilayer substrate 10 has a first region A1, a second region A2, and a third region A3. The first region A1 and the third region A3 are the regions of the multilayer substrate 10 that are not bent. The second region A2 is the region of the multilayer substrate 10 that is bent.

[0083] Here, the vertical direction in the first region A1 and the third region A3 is defined as the Z-axis direction. The second region A2 is bent relative to the first region A1 along the Z-axis direction. Bending of the multilayer substrate 10 means that the multilayer substrate 10 is deformed by applying an external force to it. The deformation of the multilayer substrate 10 can be elastic deformation, plastic deformation, or a combination of both.

[0084] [Manufacturing method of multilayer substrate 10]

[0085] Next, the manufacturing method of the multilayer substrate 10 will be described. Figure 5 This is a cross-sectional view of the multilayer substrate 10 during manufacturing.

[0086] The manufacturing method of the multilayer substrate 10 described below is a manufacturing method of a multilayer substrate 10 having a stack 12. The stack 12 has a plurality of insulating layers 14a, 14b, 15a, 14c, 14d, 15b, and 14e stacked in a structure arranged sequentially in a downward direction (first direction). The plurality of insulating layers 14a, 14b, 15a, 14c, 14d, 15b, and 14e include an insulating layer 14b (third insulating layer) having a lower main surface (ninth main surface) and an upper main surface (tenth main surface), an insulating layer 15a (first insulating layer) having a lower main surface (first main surface) and an upper main surface (second main surface), and an insulating layer 14c (second insulating layer) having a lower main surface (seventh main surface) and an upper main surface (eighth main surface). The lower principal surface (seventh principal surface) of insulating layer 14c is located below (in the first direction) the upper principal surface (eighth principal surface) of insulating layer 14c. The lower principal surface (ninth principal surface) of insulating layer 14b is located below (in the first direction) the upper principal surface (tenth principal surface) of insulating layer 14b.

[0087] First, an insulating layer 14c (second insulating layer) with a reference conductor layer 26a (first metal foil layer) is prepared on the upper main surface (eighth main surface) (second preparation step). An insulating layer 14b (third insulating layer) with a reference conductor layer 22 (second metal foil layer) is prepared on the lower main surface (ninth main surface) (third preparation step). Specifically, metal foils are adhered to the upper main surface of insulating layer 14a, the lower main surface of insulating layer 14b, the upper main surface of insulating layer 14c, the lower main surface of insulating layer 14d, and the upper main surface of insulating layer 14e. Then, the metal foils are patterned using a photolithography process. This forms the first signal conductor layer 20, reference conductor layers 22, 24, 26a, 26b, signal terminals 40, 50, and reference terminals 42, 44, 52, 54.

[0088] Next, an insulating layer 15a (first insulating layer) with a first through-hole and a second through-hole is prepared (first preparation step). Specifically, a laser beam is irradiated onto insulating layers 14a-14d, 15a, and 15b to form multiple through-holes. The multiple through-holes are formed at the locations of interlayer connecting conductors v1-v7.

[0089] Next, a conductive paste is filled into the through holes formed in the insulating layers 14c and 14d.

[0090] Following the second preparation step, a conductive paste is applied onto the reference conductor layer 26a (first metal foil layer) (coating step). Specifically, the conductive paste is applied to the lower main surface of the reference conductor layer 22, the upper main surface of the reference conductor layer 26a, the lower main surface of the reference conductor layer 26b, and the upper main surface of the reference conductor layer 24. At this time, the volume of the conductive paste applied is sufficiently larger than the volume of the through-holes in the insulating layers 15a and 15b. The conductive paste has a rectangular ring shape when viewed in the vertical direction.

[0091] After the coating process, insulating layers 14b (third insulating layer), 15a (first insulating layer), and 14c (second insulating layer) are stacked, and conductive paste is filled into the first and second through holes, causing the conductive paste to overflow from the first and second through holes. This forms a conductive paste on the reference conductor layer 26a (first metal foil layer) that is in contact with the conductive paste in the first and second through holes (lamination process). More specifically, insulating layers 14a, 14b, 15a, 14c, 14d, 15b, and 14e are stacked sequentially from top to bottom. Then, insulating layers 14a, 14b, 15a, 14c, 14d, 15b, and 14e are subjected to heat treatment and pressure treatment. Through pressure, conductive paste is filled into the through holes formed in insulating layers 15a and 15b. As described above, the volume of the conductive paste is sufficiently larger than the volume of the through-holes in the insulating layers 15a and 15b. Therefore, it remains on the lower main surface of the reference conductor layer 22, the upper main surface of the reference conductor layer 26a, the lower main surface of the reference conductor layer 26b, and the upper main surface of the reference conductor layer 24. Furthermore, the conductive paste is cured by heating. The curing of the conductive paste within the through-holes forms interlayer connection conductors v1 to v6 and multiple interlayer connection conductors v7. Additionally, the curing of the conductive paste on the lower main surface of the reference conductor layer 22, the upper main surface of the reference conductor layer 26a, the lower main surface of the reference conductor layer 26b, and the upper main surface of the reference conductor layer 24 forms the first conductor layers 28b and 28c and the second conductor layers 28a and 28d.

[0092] Finally, a protective layer 16 is formed on the insulating layer 14a by printing resin. After the above processes, the multilayer substrate 10 is completed.

[0093] [Effect]

[0094] According to the multilayer substrate 10, defects in the connection between interlayer connection conductors v11, v21 and reference conductor layer 26a, and in the connection between interlayer connection conductors v11, v21 and reference conductor layer 22, can be suppressed. More specifically, the first conductor layer 28b is connected to the lower main surface of the insulating layer 15a, and is also connected to the interlayer connection conductors v11 and v21. Moreover, the composition of the first conductor layer 28b is the same as that of the interlayer connection conductors v11 and v21. Therefore, the lower ends of the interlayer connection conductors v11 and v21 are reliably connected by the first conductor layer 28b. Furthermore, the reference conductor layer 26a is connected to the lower main surface of the first conductor layer 28b. Therefore, the lower ends of the interlayer connection conductors v11 and v21 are reliably electrically connected by the reference conductor layer 26a.

[0095] Furthermore, as described above, the composition of the first conductor layer 28b is the same as that of the interlayer connection conductors v11 and v21. Therefore, by filling the through-holes with a greater amount of conductive paste, the interlayer connection conductors v11 and v21, as well as the first conductor layer 28b, can be formed simultaneously. Thus, sufficient conductive paste is filled into the interlayer connection conductors v11 and v21. Therefore, it is difficult for insufficient filling of the conductive paste into the interlayer connection conductors v11 and v21 to occur. Thus, the upper ends of the interlayer connection conductors v11 and v21 are reliably electrically connected to the reference conductor layer 22. As described above, according to the multilayer substrate 10, it is possible to suppress defects in the connection between the interlayer connection conductors v11 and v21 and the reference conductor layer 26a, as well as in the connection between the interlayer connection conductors v11 and v21 and the reference conductor layer 22.

[0096] Furthermore, according to the multilayer substrate 10, poor connection between the interlayer connection conductors v11 and v21 and the reference conductor layer 26a can be suppressed. More specifically, the area of ​​the first conductor layer 28b is sufficiently larger than the area of ​​the lower ends of the interlayer connection conductors v11 and v21. Therefore, the lower ends of the interlayer connection conductors v11 and v21 are less likely to protrude from the first conductor layer 28b. That is, the interlayer connection conductors v11 and v21 are more reliably connected to the first conductor layer 28b. In addition, the reference conductor layer 26a is connected to the lower main surface of the first conductor layer 28b. That is, the reference conductor layer 26a and the first conductor layer 28b are more reliably connected. As a result, according to the multilayer substrate 10, poor connection between the interlayer connection conductors v11 and v21 and the reference conductor layer 26a can be suppressed.

[0097] According to the multilayer substrate 10, noise intrusion from the outside of the multilayer substrate 10 into the first signal conductor layer 20 and noise radiation from the first signal conductor layer 20 into the multilayer substrate 10 are suppressed. More specifically, reference conductor layers 22, 24, 26a, and 26b are connected to a reference potential. Therefore, the first conductor layers 28b and 28c and the second conductor layers 28a and 28d are also connected to the reference potential. Thus, in addition to the reference conductor layers 22, 24, 26a, and 26b, the first conductor layers 28b and 28c and the second conductor layers 28a and 28d also function as shielding layers. As a result, according to the multilayer substrate 10, noise intrusion from the outside of the multilayer substrate 10 into the first signal conductor layer 20 and noise radiation from the first signal conductor layer 20 into the multilayer substrate 10 are suppressed. In particular, the first conductor layer 28b has a ring shape surrounding the first signal conductor layer 20 when viewed in the vertical direction. The first signal conductor layer 20 is a circuit element that radiates noise. This more effectively suppresses noise intrusion from the outside of the multilayer substrate 10 into the first signal conductor layer 20, and noise radiation from the first signal conductor layer 20 to the outside of the multilayer substrate 10.

[0098] According to the multilayer substrate 10, the insulating layers 14a-14e, 15a, and 15b comprise thermoplastic resin. This allows the multilayer substrate 10 to be easily plastically deformed.

[0099] According to the multilayer substrate 10, the interlayer connection conductor v21 is the interlayer connection conductor closest to the interlayer connection conductor v11. Thus, the interlayer connection conductors v11 and v21, and the first conductor layer 28b, are formed by allowing conductive paste to overflow from the through-hole. As a result, poor connections between the interlayer connection conductors v11 and v21 and the reference conductor layer 26a, as well as between the interlayer connection conductors v11 and v21 and the reference conductor layer 22, can be suppressed.

[0100] (First variation)

[0101] Hereinafter, the multilayer substrate 10a of the first modified example will be described with reference to the accompanying drawings. Figure 6 This is a cross-sectional view of the multilayer substrate 10a.

[0102] Multilayer substrate 10a differs from multilayer substrate 10 in that it does not have second conductor layers 28a and 28d. The other structures of multilayer substrate 10a are the same as those of multilayer substrate 10. Thus, in multilayer substrate 10a, the second conductor layers 28a and 28d are not essential components. Multilayer substrate 10a can achieve the same functional effects as multilayer substrate 10.

[0103] (Second variation)

[0104] Hereinafter, the multilayer substrate 10b of the second modified example will be described with reference to the accompanying drawings. Figure 7This is a cross-sectional view of the multilayer substrate 10b.

[0105] The multilayer substrate 10b differs from the multilayer substrate 10a in that it lacks the protective layer 16 and the insulating layers 14a, 14b, and 14e. The other structures of the multilayer substrate 10a are the same as those of the multilayer substrate 10. Thus, the insulating layer 15a, which has interlayer connection conductors v11 and v21, can also be located on the top layer of the laminate 12. The insulating layer 15b, which has interlayer connection conductors v14 and v24, can also be located on the bottom layer of the laminate 12. The multilayer substrate 10b can achieve the same functional effect as the multilayer substrate 10a.

[0106] (Third variation)

[0107] Hereinafter, the multilayer substrate 10c of the third modified example will be described with reference to the accompanying drawings. Figure 8 This is a cross-sectional view of the multilayer substrate 10c.

[0108] The multilayer substrate 10c differs from the multilayer substrate 10 in that it has reference conductor layers 26a-1, 26a-2, 26b-1, and 26b-2 (first metal foil layers) instead of reference conductor layers 26a and 26b, and reference conductor layers 22-1, 22-2, 24-1, and 24-2 (second metal foil layers) instead of reference conductor layers 22 and 24.

[0109] More specifically, in the multilayer substrate 10, the reference conductor layer 26a (a first metal foil layer included in more than one first metal foil layer) overlaps with both the interlayer connection conductor v11 (first interlayer connection conductor) and the interlayer connection conductor v21 (second interlayer connection conductor) when viewed in the downward direction (first direction). The reference conductor layer 22 (a second metal foil layer included in more than one second metal foil layer) overlaps with both the interlayer connection conductor v11 (first interlayer connection conductor) and the interlayer connection conductor v21 (second interlayer connection conductor) when viewed in the downward direction (first direction).

[0110] On the other hand, in the multilayer substrate 10c, reference conductor layer 26a-1 (first metal foil layer) overlaps with interlayer connection conductor v11 (first interlayer connection conductor) when viewed in the downward direction (first direction). Reference conductor layer 26a-2 (first metal foil layer) overlaps with interlayer connection conductor v21 (second interlayer connection conductor) when viewed in the downward direction (first direction). Reference conductor layer 22-1 (second metal foil layer) overlaps with interlayer connection conductor v11 (first interlayer connection conductor) when viewed in the downward direction (first direction). Reference conductor layer 22-2 (second metal foil layer) overlaps with interlayer connection conductor v21 (second interlayer connection conductor) when viewed in the downward direction (first direction). It should be noted that reference conductor layers 26b-1, 26b-2, 24-1, and 24-2 have a structure that is symmetrical about the top and bottom of reference conductor layers 26a-1, 26a-2, 22-1, and 22-2, therefore, the description is omitted. The other structures of the multilayer substrate 10c are the same as those of the multilayer substrate 10, so the description is omitted. The multilayer substrate 10c performs the same function as the multilayer substrate 10.

[0111] (Fourth variation)

[0112] Hereinafter, the multilayer substrate 10d of the fourth modified example will be described with reference to the accompanying drawings. Figure 9 This is a top view of the insulating layer 15a of the multilayer substrate 10d.

[0113] Multiple through-holes H can also be provided in the insulating layer 15a. Similarly, multiple through-holes H can also be provided in the insulating layer 15b. As a result, the dielectric constant near the first signal conductor layer 20 becomes lower. Consequently, the dielectric loss of the first high-frequency signal transmitted in the first signal conductor layer 20 is reduced.

[0114] (Fifth variation)

[0115] Hereinafter, the multilayer substrate 10e of the fifth modified example will be described with reference to the accompanying drawings. Figure 10 This is a top view of the insulating layer 15a of the multilayer substrate 10e.

[0116] The multiple interlayer connecting conductors v7 may not be arranged in a single column along the sides of the laminate 12 when viewed in the vertical direction. More specifically, the multiple interlayer connecting conductors v7 may also be arranged in two columns along the sides of the laminate 12. In this case, the multiple interlayer connecting conductors v7 are configured in a zigzag pattern.

[0117] (Sixth variation)

[0118] Hereinafter, the multilayer substrate 10f of the sixth modified example will be described with reference to the accompanying drawings. Figure 11 This is a top-view view of the multilayer substrate 10f.

[0119] The multilayer substrate 10f differs from the multilayer substrate 10 in that it has first signal conductor layers 20a and 20b in place of the first signal conductor layer 20, and also has second signal conductor layers 120a and 120b. More specifically, a first high-frequency signal is transmitted on the first signal conductor layers 20a and 20b. The first high-frequency signal is a digital signal. A second high-frequency signal is transmitted on the second signal conductor layers 120a and 120b. The second high-frequency signal is an analog signal.

[0120] When viewed vertically, multiple interlayer connecting conductors v7 are arranged in a row along the left-right direction at the center of the front-back direction of the insulating layer 15a. These interlayer connecting conductors v7 are referred to as multiple interlayer connecting conductors v17. The multiple interlayer connecting conductors v17 include multiple interlayer connecting conductors v7a and multiple interlayer connecting conductors v7b. The multiple interlayer connecting conductors v7a and multiple interlayer connecting conductors v7b are arranged alternately in the left-right direction.

[0121] The first signal conductor layers 20a and 20b are located ahead of the plurality of interlayer connecting conductors v17. The second signal conductor layers 120a and 120b are located behind the plurality of interlayer connecting conductors v17. Therefore, the plurality of interlayer connecting conductors v11 (first interlayer connecting conductors) and the plurality of interlayer connecting conductors v21 (second interlayer connecting conductors) included in the plurality of interlayer connecting conductors v17 are located between the first signal conductor layers 20a and 20b and the second signal conductor layers 120a and 120b when viewed in the downward direction (first direction).

[0122] Here, the forward direction (third direction) refers to the direction from the interlayer connecting conductor v11 (first interlayer connecting conductor) included in the interlayer connecting conductor v17 located between the first signal conductor layers 20a, 20b and the second signal conductor layers 120a, 120b when viewed along the downward direction (first direction), toward the first signal conductor layers 20a, 20b. The backward direction (fourth direction) refers to the direction from the interlayer connecting conductor v11 (first interlayer connecting conductor) included in the interlayer connecting conductor v17 located between the first signal conductor layers 20a, 20b and the second signal conductor layers 120a, 120b when viewed along the downward direction (first direction), toward the second signal conductor layers 120a, 120b. At this time, in the region located in the forward direction (third direction) of the interlayer connecting conductor v11 (first interlayer connecting conductor), no signal conductor layer for transmitting analog signals is provided. That is, in the region located in the direction forward (third direction) of the interlayer connection conductor v11 (first interlayer connection conductor), only the first signal conductor layers 20a and 20b for transmitting digital signals are provided. In the region located in the direction backward (fourth direction) of the interlayer connection conductor v11 (first interlayer connection conductor), no signal conductor layer for transmitting digital signals is provided. That is, in the region located in the direction backward (fourth direction) of the interlayer connection conductor v11 (first interlayer connection conductor), only the second signal conductor layers 120a and 120b for transmitting analog signals are provided. The other structures of the multilayer substrate 10f are the same as those of the multilayer substrate 10, so the description is omitted. The multilayer substrate 10f can achieve the same functional effect as the multilayer substrate 10.

[0123] Furthermore, according to the multilayer substrate 10f, a plurality of interlayer interconnecting conductors v11 are located between the first signal conductor layers 20a, 20b and the second signal conductor layers 120a, 120b. As a result, the isolation between the first signal conductor layers 20a, 20b and the second signal conductor layers 120a, 120b is improved.

[0124] (Seventh variation)

[0125] Hereinafter, the multilayer substrate 10g of the seventh modified example will be described with reference to the accompanying drawings. Figure 12 This is a bottom view of the insulating layer 15a of the multilayer substrate 10g.

[0126] The multilayer substrate 10g also includes an interlayer connection conductor v31, a third conductor layer 128b, and a fourth conductor layer 228b. The interlayer connection conductor v31 (the third interlayer connection conductor) penetrates the insulating layer 15a (the first insulating layer) in the downward direction (first direction).

[0127] The first conductor layer 28b is connected to the interlayer connecting conductor v11 (first interlayer connecting conductor) and the interlayer connecting conductor v21 (second interlayer connecting conductor). The third conductor layer 128b is connected to the lower main surface (first main surface) of the insulating layer 15a (first insulating layer). The third conductor layer 128b is connected to the interlayer connecting conductor v21 (second interlayer connecting conductor) and the interlayer connecting conductor v31 (third interlayer connecting conductor). The fourth conductor layer 228b is connected to the lower main surface (first main surface) of the insulating layer 15a (first insulating layer). The fourth conductor layer 228b is connected to the interlayer connecting conductor v31 (third interlayer connecting conductor) and the interlayer connecting conductor v11 (first interlayer connecting conductor).

[0128] Furthermore, the first conductor layer 28b is connected to the fourth conductor layer 228b. On the other hand, the third conductor layer 128b is not connected to either the first conductor layer 28b or the fourth conductor layer 228b. The multilayer substrate 10g described above can achieve the same functional effect as the multilayer substrate 10.

[0129] (Eighth variation)

[0130] Hereinafter, the multilayer substrate 10h of the eighth modified example will be described with reference to the accompanying drawings. Figure 13 This is a cross-sectional view of the insulating layer 15a of the multilayer substrate 10h, orthogonal to the vertical direction. The cross-section is located at the center of the insulating layer 15a in the vertical direction.

[0131] The distance D1 between the interlayer connecting conductor v11 (first interlayer connecting conductor) and the interlayer connecting conductor v21 (second interlayer connecting conductor) is shorter than the diameter R of the interlayer connecting conductor v11 (first interlayer connecting conductor). The diameter R of the interlayer connecting conductor v11 is the diameter of the interlayer connecting conductor v11 in the cross-section located at the center of the vertical direction of the insulating layer 15a.

[0132] (Other implementation methods)

[0133] The multilayer substrate of the present invention is not limited to multilayer substrates 10, 10a to 10h, and can be modified within the scope of its spirit. It should be noted that the structures of multilayer substrates 10, 10a to 10h can also be arbitrarily combined.

[0134] It should be noted that in the multilayer substrates 10, 10a to 10h, the interlayer connection conductors v11 (first interlayer connection conductor) and v21 (second interlayer connection conductor) include metals having melting points lower than those of the reference conductor layer 26a (first metal foil layer) and the reference conductor layer 22 (second metal foil layer). In this case, the interlayer connection conductors v11 (first interlayer connection conductor) and v21 (second interlayer connection conductor) may not include resin. Such interlayer connection conductors v11 (first interlayer connection conductor) and v21 (second interlayer connection conductor) may, for example, include solder. The solder includes Pb and Sn. However, the solder may not include Pb.

[0135] It should be noted that one or more first metal foil layers may include one or more reference conductor layers (first metal foil layers). Therefore, one or more first metal foil layers may also include two or more reference conductor layers (first metal foil layers).

[0136] It should be noted that one or more second metal foil layers may include one or more reference conductor layers (second metal foil layers). Therefore, one or more second metal foil layers may also include two or more reference conductor layers (second metal foil layers).

[0137] It should be noted that the second conductor layer 28a is not a necessary component. Additionally, conductor layers 24 and 26b, the first conductor layer 28c, and the second conductor layer 28d are not necessary components.

[0138] It should be noted that the first signal conductor layer 20 is not a necessary component.

[0139] It should be noted that reference conductor layers 22, 24, 26a, and 26b can also be connected to potentials other than ground potential.

[0140] It should be noted that the first metal foil layer and the second metal foil layer can also be conductor layers other than the reference conductor layer. For example, the first metal foil layer and the second metal foil layer can also be signal conductor layers for transmitting high-frequency signals.

[0141] It should be noted that the interlayer connecting conductor v11 (the first interlayer connecting conductor) and the interlayer connecting conductor v21 (the second interlayer connecting conductor) may not be adjacent. Therefore, other conductors may also be placed between the interlayer connecting conductor v11 and the interlayer connecting conductor v21.

[0142] It should be noted that in the multilayer substrate 10g, the first conductor layer 28b and the fourth conductor layer 228b may not be connected.

[0143] It should be noted that the distance D1 between the interlayer connecting conductor v11 (the first interlayer connecting conductor) and the interlayer connecting conductor v21 (the second interlayer connecting conductor) can also be greater than or equal to the diameter R of the interlayer connecting conductor v11 (the first interlayer connecting conductor).

[0144] It should be noted that metal paste can also be used instead of conductive paste. Metal paste is a mixture of metal and liquid flux. Metal paste is, for example, solder paste. In the case of solder paste, the metal is, for example, an alloy of Sn and Pb. However, the metal may not include Pb.

[0145] It should be noted that the first high-frequency signal can also be an analog signal. The second high-frequency signal can also be a digital signal.

[0146] It should be noted that the circuit elements of radiated noise can also be ICs (Integrated Circuits), high-frequency circuits, active components, and electronic components.

[0147] It should be noted that insulating layers 14a-14e, 15a, and 15b may also include materials other than thermoplastic resins.

[0148] It should be noted that a diffusion layer may also be formed at the boundary between the interlayer connecting conductors v11, v21 and the reference conductor layer 22. A diffusion layer may also be formed at the boundary between the interlayer connecting conductors v11, v21 and the reference conductor layer 26a. A diffusion layer may also be formed at the boundary between the interlayer connecting conductors v14, v24 and the reference conductor layer 26b. A diffusion layer may also be formed at the boundary between the interlayer connecting conductors v14, v24 and the reference conductor layer 24. The diffusion layer is a region where an alloy of the metals contained in the interlayer connecting conductors v11, v21 and the metals contained in the reference conductor layers 22, 24, 26a, 26b is formed. For example, if the reference conductor layer 22 (the first metal foil layer) is a Cu metal foil and the interlayer connecting conductors v11, v21 include SnAgCu, the diffusion layer includes a Cu-Sn alloy.

[0149] It should be noted that the first signal conductor layer 20 can also be bent in a direction orthogonal to the vertical direction (e.g., the front-back direction) when viewed along the vertical direction. The first signal conductor layer 20 can also be bent in a direction orthogonal to the vertical direction by plastic deformation and / or elastic deformation of the multilayer substrate 10. Alternatively, the first signal conductor layer 20 can be bent in a direction orthogonal to the vertical direction without deformation of the multilayer substrate 10.

[0150] It should be noted that the first conductor layers 28b and 28c and the second conductor layers 28a and 28d can also have the following characteristics when viewed in the vertical direction: Figure 1Shapes other than the rectangular ring shape shown. The first conductor layers 28b, 28c and the second conductor layers 28a, 28d can also be curved, meandering or straight, for example.

[0151] It should be noted that the coating shape of the conductive paste can also be any shape other than a rectangular ring when viewed vertically. The coating shape of the conductive paste can also be divided into multiple regions. For example, as a process example of dividing the coating shape of the conductive paste into multiple regions, a process using a metal mask with multiple through holes arranged in a ring shape is given. In this case, the multiple conductive pastes may not be in contact with each other. Alternatively, the multiple conductive pastes may be brought into contact with each other during pressing.

[0152] It should be noted that the shape of the through hole is not limited to a circle; it can also be a quadrilateral or other shapes. Additionally, the through hole can also be a rectangle following the shape of the electrode.

[0153] It should be noted that the fourth direction does not necessarily have to be the opposite direction of the third direction.

[0154] It should be noted that the first signal conductor layers 20a and 20b and the second signal conductor layers 120a and 120b can also be disposed on different insulating layers.

[0155] The present invention has the following structure.

[0156] (1) A multilayer substrate comprising:

[0157] A laminate having a configuration in which multiple insulating layers are stacked and arranged along a first direction, the multiple insulating layers including a first insulating layer having a first main surface and a second main surface, the first main surface being located closer to the first direction than the second main surface;

[0158] Multiple interlayer connecting conductors penetrate the first insulating layer along the first direction, and include a first interlayer connecting conductor and a second interlayer connecting conductor;

[0159] A first conductor layer is connected to the first main surface of the first insulator layer, and to the first interlayer connecting conductor and the second interlayer connecting conductor, and has a third main surface and a fourth main surface, wherein the third main surface is located closer to the first direction than the fourth main surface, and the composition of the first conductor layer is the same as the composition of the first interlayer connecting conductor and the second interlayer connecting conductor.

[0160] One or more first metal foil layers are connected to the third main surface of the first conductor layer, and the one or more first metal foil layers overlap with the first interlayer connecting conductor and the second interlayer connecting conductor when viewed along the first direction; the composition of the one or more first metal foil layers is different from the composition of the first conductor layer; and

[0161] One or more second metal foil layers are located in a second direction of the first insulating layer, the second direction being the opposite direction to the first direction. When viewed along the first direction, the one or more second metal foil layers overlap with the first interlayer connecting conductor and the second interlayer connecting conductor, and are electrically connected to the first interlayer connecting conductor and the second interlayer connecting conductor. The composition of the one or more second metal foil layers is different from that of the first conductor layer.

[0162] (2) According to the multilayer substrate described in (1), wherein,

[0163] The second interlayer connection conductor is the interlayer connection conductor closest to the first interlayer connection conductor.

[0164] (3) The multilayer substrate as described in (1) or (2), wherein,

[0165] One of the more than one first metal foil layers overlaps with both the first interlayer connecting conductor and the second interlayer connecting conductor when viewed along the first direction.

[0166] (4) The multilayer substrate described in any one of (1) to (3), wherein,

[0167] One of the more than one second metal foil layers overlaps both the first interlayer connecting conductor and the second interlayer connecting conductor when viewed along the first direction.

[0168] (5) The multilayer substrate described in any one of (1) to (4), wherein,

[0169] The multilayer substrate further comprises a second conductor layer, which is connected to the second main surface of the first insulating layer, and to the first interlayer connection conductor and the second interlayer connection conductor. The second conductor layer has a fifth main surface and a sixth main surface, the fifth main surface being located closer to the first main surface in the first direction than the sixth main surface. The composition of the second conductor layer is the same as the composition of the first interlayer connection conductor and the second interlayer connection conductor.

[0170] The one or more second metal foil layers are in contact with the sixth main surface of the second conductor layer.

[0171] (6) The multilayer substrate described in any one of (1) to (5), wherein,

[0172] The first interlayer connecting conductor and the second interlayer connecting conductor comprise resin and metal.

[0173] (7) The multilayer substrate described in any one of (1) to (5), wherein,

[0174] The first interlayer connecting conductor and the second interlayer connecting conductor comprise metals having melting points lower than the melting points of the first metal foil layer and the second metal foil layer.

[0175] (8) The multilayer substrate described in (7), wherein,

[0176] The first interlayer connecting conductor and the second interlayer connecting conductor do not include resin.

[0177] (9) The multilayer substrate described in any one of (1) to (8), wherein,

[0178] The multilayer substrate also includes:

[0179] A third interlayer connecting conductor, which penetrates the first insulating layer along the first direction; and

[0180] The third conductor layer is connected to the first main surface of the first insulator layer, and is also connected to the second interlayer connection conductor and the third interlayer connection conductor.

[0181] (10) The multilayer substrate described in (9), wherein,

[0182] The multilayer substrate further includes a fourth conductor layer, which is connected to the first main surface of the first insulator layer and to the third interlayer connection conductor and the first interlayer connection conductor.

[0183] (11) The multilayer substrate described in any one of (1) to (10), wherein,

[0184] The distance between the first interlayer connecting conductor and the second interlayer connecting conductor is shorter than the diameter of the first interlayer connecting conductor.

[0185] (12) The multilayer substrate described in any one of (1) to (11), wherein,

[0186] The multilayer substrate also includes a first signal conductor layer for transmitting a first high-frequency signal.

[0187] (13) According to the multilayer substrate described in (12), wherein,

[0188] The distance between the first interlayer connecting conductor and the second interlayer connecting conductor is shorter than the distance between the first interlayer connecting conductor and the first signal conductor layer.

[0189] (14) The multilayer substrate according to (12) or (13), wherein,

[0190] The first high-frequency signal is a digital signal.

[0191] (15) The multilayer substrate described in any one of (12) to (14), wherein,

[0192] The multilayer substrate also includes a second signal conductor layer for transmitting a second high-frequency signal.

[0193] The first interlayer connecting conductor is located between the first signal conductor layer and the second signal conductor layer when viewed along the first direction.

[0194] (16) According to the multilayer substrate described in (15), wherein,

[0195] The second high-frequency signal is an analog signal.

[0196] (17) According to the multilayer substrate described in (16), wherein,

[0197] The third direction is from the first interlayer connection conductor located between the first signal conductor layer and the second signal conductor layer when viewed along the first direction, toward the first signal conductor layer.

[0198] The fourth direction is from the first interlayer connection conductor located between the first signal conductor layer and the second signal conductor layer when viewed along the first direction, toward the second signal conductor layer.

[0199] In the region located at a third-direction position relative to the first interlayer connecting conductor, no signal conductor layer for transmitting analog signals is provided.

[0200] In the region located in the fourth direction, which is closer to the first interlayer connecting conductor, no signal conductor layer for transmitting digital signals is provided.

[0201] (18) According to the multilayer substrate described in (12), wherein,

[0202] The first conductor layer has a ring shape surrounding the first signal conductor layer when viewed along the first direction.

[0203] (19) According to the multilayer substrate described in (18), wherein,

[0204] The first conductor layer surrounds the circuit elements that radiate noise when viewed along the first direction.

[0205] (20) The multilayer substrate described in any one of (1) to (19), wherein,

[0206] The plurality of insulating layers comprise thermoplastic resin.

[0207] (21) An electronic device comprising a multilayer substrate as described in any one of (1) to (20).

[0208] (22) A method for manufacturing a multilayer substrate, the multilayer substrate comprising a laminate having a configuration in which a plurality of insulating layers, including a third insulating layer, a first insulating layer, and a second insulating layer, are stacked in sequence along a first direction, the third insulating layer having a ninth main surface and a tenth main surface, the first insulating layer having a first main surface and a second main surface, and the second insulating layer having a seventh main surface and an eighth main surface, wherein...

[0209] The first main surface is located in the first direction, which is closer to the second main surface.

[0210] The seventh principal plane is located in the first direction closer to the eighth principal plane.

[0211] The ninth principal plane is located in the first direction closer to the tenth principal plane.

[0212] The method for manufacturing the multilayer substrate includes:

[0213] The first preparation step is to prepare the first insulating layer having a first through hole and a second through hole.

[0214] The second preparation step involves preparing the second insulating layer on the eighth main surface, to which the first metal foil layer is disposed;

[0215] The third preparation step is to prepare the third insulating layer on the ninth main surface where the second metal foil layer is provided;

[0216] The coating process, following the second preparation process, involves applying a conductive paste or metal grease onto the first metal foil layer; and

[0217] In the lamination process, after the coating process, the third insulating layer, the first insulating layer, and the second insulating layer are stacked, and the conductive paste or the metal paste is filled into the first through hole and the second through hole, and the conductive paste or the metal paste overflows from the first through hole and the second through hole, thereby forming the conductive paste or the metal paste in the first through hole and the conductive paste or the metal paste in contact with the conductive paste or the metal paste in the first through hole onto the first metal foil layer.

[0218] Explanation of reference numerals in the attached figures

[0219] 10, 10a~10h: Multilayer substrate;

[0220] 12: Layered body;

[0221] 14a~14e, 15a, 15b: Insulating layer;

[0222] 16: Protective layer;

[0223] 20, 20a, 20b: First signal conductor layer;

[0224] 22, 22-1, 22-2, 24, 26a, 26a-1, 26a-2, 26b, 26b-1: Reference conductor layer;

[0225] 28a, 28d: Second conductor layer;

[0226] 28b, 28c: First conductor layer;

[0227] 100: Electronic devices;

[0228] 102: Shell;

[0229] 120a, 120b: Second signal conductor layer;

[0230] 128b: Third conductor layer;

[0231] 228b: Fourth conductor layer;

[0232] A1: First area;

[0233] A2: Second area;

[0234] A3: Third area;

[0235] H: Through hole;

[0236] S1: Plane;

[0237] v1~v7, v7a, v7b, v11~v14, v17, v21~v24, v31: Interlayer connection conductors.

Claims

1. A multilayer substrate, comprising: A laminate having a configuration in which multiple insulating layers are stacked and arranged along a first direction, the multiple insulating layers including a first insulating layer having a first main surface and a second main surface, the first main surface being located closer to the first direction than the second main surface; Multiple interlayer connecting conductors penetrate the first insulating layer along the first direction, and include a first interlayer connecting conductor and a second interlayer connecting conductor; A first conductor layer is connected to the first main surface of the first insulator layer, and to the first interlayer connecting conductor and the second interlayer connecting conductor, and has a third main surface and a fourth main surface, wherein the third main surface is located closer to the first direction than the fourth main surface, and the composition of the first conductor layer is the same as the composition of the first interlayer connecting conductor and the second interlayer connecting conductor. One or more first metal foil layers are connected to the third main surface of the first conductor layer, and the one or more first metal foil layers overlap with the first interlayer connecting conductor and the second interlayer connecting conductor when viewed along the first direction; the composition of the one or more first metal foil layers is different from the composition of the first conductor layer; and One or more second metal foil layers are located in a second direction of the first insulating layer, the second direction being the opposite of the first direction. When viewed along the first direction, the one or more second metal foil layers overlap with and are electrically connected to both the first and second interlayer connecting conductors. The composition of the one or more second metal foil layers differs from that of the first conductor layer. The first interlayer connecting conductor and the second interlayer connecting conductor comprise resin and metal, or the first interlayer connecting conductor and the second interlayer connecting conductor comprise metal having a melting point lower than that of the first metal foil layer and the second metal foil layer. The multilayer substrate also includes a first signal conductor layer for transmitting a first high-frequency signal. When viewed along the first direction, the first signal conductor layer does not overlap with the first conductor layer.

2. The multilayer substrate according to claim 1, wherein, The second interlayer connection conductor is the interlayer connection conductor closest to the first interlayer connection conductor.

3. The multilayer substrate according to claim 1 or 2, wherein, One of the more than one first metal foil layers overlaps with both the first interlayer connecting conductor and the second interlayer connecting conductor when viewed along the first direction.

4. The multilayer substrate according to claim 1 or 2, wherein, One of the more than one second metal foil layers overlaps both the first interlayer connecting conductor and the second interlayer connecting conductor when viewed along the first direction.

5. The multilayer substrate according to claim 1 or 2, wherein, The multilayer substrate further comprises a second conductor layer, which is connected to the second main surface of the first insulating layer, and to the first interlayer connection conductor and the second interlayer connection conductor. The second conductor layer has a fifth main surface and a sixth main surface, the fifth main surface being located closer to the first main surface in the first direction than the sixth main surface. The composition of the second conductor layer is the same as the composition of the first interlayer connection conductor and the second interlayer connection conductor. The one or more second metal foil layers are in contact with the sixth main surface of the second conductor layer.

6. The multilayer substrate according to claim 1, wherein, The first interlayer connecting conductor and the second interlayer connecting conductor do not include resin.

7. The multilayer substrate according to claim 1 or 2, wherein, The multilayer substrate also includes: A third interlayer connecting conductor, which penetrates the first insulating layer along the first direction; and The third conductor layer is connected to the first main surface of the first insulator layer, and is also connected to the second interlayer connection conductor and the third interlayer connection conductor.

8. The multilayer substrate according to claim 7, wherein, The multilayer substrate further includes a fourth conductor layer, which is connected to the first main surface of the first insulator layer and to the third interlayer connection conductor and the first interlayer connection conductor.

9. The multilayer substrate according to claim 1 or 2, wherein, The distance between the first interlayer connecting conductor and the second interlayer connecting conductor is shorter than the diameter of the first interlayer connecting conductor.

10. The multilayer substrate according to claim 1, wherein, The distance between the first interlayer connecting conductor and the second interlayer connecting conductor is shorter than the distance between the first interlayer connecting conductor and the first signal conductor layer.

11. The multilayer substrate according to claim 1, wherein, The first high-frequency signal is a digital signal.

12. The multilayer substrate according to claim 1, wherein, The multilayer substrate also includes a second signal conductor layer for transmitting a second high-frequency signal. The first interlayer connecting conductor is located between the first signal conductor layer and the second signal conductor layer when viewed along the first direction.

13. The multilayer substrate according to claim 12, wherein, The second high-frequency signal is an analog signal.

14. The multilayer substrate according to claim 13, wherein, The third direction is from the first interlayer connection conductor located between the first signal conductor layer and the second signal conductor layer when viewed along the first direction, toward the first signal conductor layer. The fourth direction is from the first interlayer connection conductor located between the first signal conductor layer and the second signal conductor layer when viewed along the first direction, toward the second signal conductor layer. In the region located at a third-direction position relative to the first interlayer connecting conductor, no signal conductor layer for transmitting analog signals is provided. In the region located in the fourth direction, which is closer to the first interlayer connecting conductor, no signal conductor layer for transmitting digital signals is provided.

15. The multilayer substrate according to claim 1, wherein, The first conductor layer has a ring shape surrounding the first signal conductor layer when viewed along the first direction.

16. The multilayer substrate according to claim 15, wherein, The first conductor layer surrounds the circuit elements that radiate noise when viewed along the first direction.

17. The multilayer substrate according to claim 1 or 2, wherein, The plurality of insulating layers comprise thermoplastic resin.

18. An electronic device comprising the multilayer substrate as described in claim 1 or 2.

19. A method for manufacturing a multilayer substrate, the multilayer substrate comprising a laminate having a configuration in which a plurality of insulating layers, including a third insulating layer, a first insulating layer, and a second insulating layer, are stacked in sequence along a first direction, the third insulating layer having a ninth main surface and a tenth main surface, the first insulating layer having a first main surface and a second main surface, and the second insulating layer having a seventh main surface and an eighth main surface, wherein... The first main surface is located in the first direction, which is closer to the second main surface. The seventh principal plane is located in the first direction closer to the eighth principal plane. The ninth principal plane is located in the first direction closer to the tenth principal plane. The method for manufacturing the multilayer substrate includes: The first preparation step is to prepare the first insulating layer having a first through hole and a second through hole. The second preparation step involves preparing the second insulating layer on the eighth main surface, to which the first metal foil layer is disposed; The third preparation step is to prepare the third insulating layer on the ninth main surface where the second metal foil layer is provided; The coating process involves applying a conductive paste or metal grease onto the first metal foil layer after the second preparation process. as well as In the lamination process, after the coating process, the third insulating layer, the first insulating layer, and the second insulating layer are stacked, and the conductive paste or the metal paste is filled into the first through-hole and the second through-hole, allowing the conductive paste or the metal paste to overflow from the first through-hole and the second through-hole. This forms the conductive paste or the metal paste within the first through-hole, as well as the conductive paste or the metal paste in contact with the conductive paste or the metal paste within the first through-hole, onto the first metal foil layer. The conductive paste or the metal paste comprises a resin and a metal, or the conductive paste or the metal paste comprises a metal having a melting point lower than that of the first metal foil layer and the second metal foil layer. The multilayer substrate also includes a first signal conductor layer for transmitting a first high-frequency signal. When viewed along the first direction, the first signal conductor layer does not overlap with the conductive paste or the metal paste.

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