Multilayer substrates and electronic devices

Abstract

A multilayer substrate and an electronic device are provided that can improve the heat dissipation and electrical characteristics of a transmission line. The multilayer substrate (10) includes a laminate (12) and a first conductor layer (signal conductor layer) (20). The laminate (12) has a structure in which multiple insulating layers (16a-16e) are stacked in the stacking direction. The first conductor layer (20) is disposed in the laminate (12). An internal space (Sp1, Sp2) is provided within the laminate (12) that is not connected to the space outside the laminate (12). The first conductor layer (20) has a first main surface and a second main surface. The second main surface has an exposed portion exposed in the internal space (Sp1, Sp2) and a portion adhered to the multiple insulating layers. The surface roughness of the second main surface is greater than the surface roughness of the first main surface.

Description

Technical Field

[0001] This utility model relates to a multilayer substrate having a structure in which multiple insulating layers are stacked. Background Technology

[0002] As a prior art invention concerning multilayer substrates, for example, the transmission line described in Patent Document 1 is known. This transmission line has a structure in which signal line conductors are formed on an insulating substrate.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2022-136284 Utility Model Content

[0006] Problems to be solved by utility models

[0007] Furthermore, in the field of transmission lines described in Patent Document 1, there is a demand for improved heat dissipation and improved electrical characteristics of the transmission lines.

[0008] Therefore, the purpose of this invention is to improve the heat dissipation of multilayer substrates and the electrical characteristics of multilayer substrate circuits.

[0009] Technical solutions for solving the problem

[0010] One aspect of this utility model relates to a multilayer substrate, characterized in that:

[0011] The multilayer substrate has a laminate and a first conductor layer.

[0012] The laminate has a structure in which multiple insulating layers are stacked in the stacking direction.

[0013] The first conductor layer is disposed in the laminate.

[0014] An internal space is provided within the stacked body.

[0015] The first conductor layer has a first main surface and a second main surface.

[0016] The second main surface has an exposed portion exposed in the internal space and a portion adhered to the plurality of insulating layers.

[0017] The surface roughness of the second principal surface is greater than that of the first principal surface.

[0018] One aspect of this utility model relates to an electronic device, characterized in that the electronic device comprises the aforementioned multilayer substrate.

[0019] Utility Model Effect

[0020] According to the multilayer substrate and electronic equipment involved in this utility model, the heat dissipation of the transmission line and the electrical characteristics of the transmission line can be improved. Attached Figure Description

[0021] Figure 1 This is an exploded perspective view of the multilayer substrate 10.

[0022] Figure 2 This is a cross-sectional view of the multilayer substrate 10.

[0023] Figure 3 This is a cross-sectional view of the multilayer substrate 10a.

[0024] Figure 4 This is a cross-sectional view of the multilayer substrate 10b.

[0025] Figure 5 This is a cross-sectional view of the multilayer substrate 10c.

[0026] Figure 6 This is a cross-sectional view of a multilayer substrate (10d).

[0027] Figure 7 This is a cross-sectional view of the multilayer substrate 10e.

[0028] Figure 8 This is a cross-sectional view of an electronic device 1 having a multilayer substrate 10. Detailed Implementation

[0029] (Implementation Method)

[0030] [Structure of multilayer substrates]

[0031] Hereinafter, the structure of the multilayer substrate 10 according to the embodiments 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. Figure 2 This is a cross-sectional view of the multilayer substrate 10. Figure 2 In, it is shown Figure 1 The cross-section at point AA. Additionally, at... Figure 1 In this paper, only representative interlayer connection conductors v3 and v4 among the multiple interlayer connection conductors v3 and v4 are marked with reference labels.

[0032] In this specification, orientations are defined as follows: The stacking direction of the laminate 12 of the multilayer substrate 10 is parallel to the vertical axis. Furthermore, the direction in which the signal conductor layer 20 of the multilayer substrate 10 extends is parallel to the horizontal axis. Additionally, when viewed from a downward direction, the linewidth direction of the signal conductor layer 20 is parallel to the front-back axis. The vertical axis, front-back axis, and horizontal axis are orthogonal to each other. However, the vertical axis, horizontal axis, and front-back axis may not be the same as those used in actual operation of the multilayer substrate 10.

[0033] 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 means the front half of X. Rear part of X means the rear half of X. Left part of X means the left half of X. Right part of X means the right half of X. Upper part of X means the upper half of X. Lower part of X means the lower half of X. Front end of X means the end of X in the forward direction. Rear end of X means the end of X in the rear direction. Left end of X means the end of X in the left direction. Right end of X means the end of X in the right direction. Upper end of X means the end of X in the upward direction. Lower end of X means the end of X in the downward direction. Front end of X means the front end and its vicinity. Rear end of X means the rear end and its vicinity. The left end of X refers to the left side of X and its vicinity. The right end of X refers to the right side of X and its vicinity. The upper end of X refers to the upper part of X and its vicinity. The lower end of X refers to the lower part of X and its vicinity.

[0034] First, refer to Figure 1 as well as Figure 2 The structure of the multilayer substrate 10 will be explained below. The multilayer substrate 10 transmits high-frequency signals. In electronic devices such as smartphones, the multilayer substrate 10 is used to electrically connect two circuits. For example... Figure 1 As shown, the multilayer substrate 10 includes a stack 12, a signal conductor layer 20 (first conductor layer), a ground conductor layer 22 (second conductor layer), a ground conductor layer 24, a ground conductor layer 25, mounting electrodes 26a, 26b, interlayer connection conductors v1, v2, multiple interlayer connection conductors v3, and multiple interlayer connection conductors v4.

[0035] The laminate 12 has a plate shape. Therefore, the laminate 12 has an upper main surface and a lower main surface located below the upper main surface. The upper and lower main surfaces of the laminate 12 have a rectangular shape with long sides extending along the left and right axes. Therefore, the length of the laminate 12 along the left and right axes is longer than the length of the laminate 12 along the front and rear axes. The laminate 12 is flexible.

[0036] like Figure 1As shown, the laminate 12 has a structure in which insulating layers 16a to 16e are laminated in the lamination direction. Each of the insulating layers 16a to 16e has an upper main surface and a lower main surface. The insulating layers 16a to 16e are arranged sequentially from top to bottom. The material of the insulating layers 16a to 16e is a resin having a water absorption rate of 0.1% or less. For example, the material of the insulating layers 16a to 16e is a thermoplastic resin. For example, a liquid crystal polymer. Thus, the material of the insulating layers 16a to 16e is a flexible resin. Furthermore, adjacent insulating layers of the insulating layers 16a to 16e in the lamination direction are fused together.

[0037] High-frequency signals are transmitted in the signal conductor layer 20. For example... Figure 1 As shown, a signal conductor layer 20 (first conductor layer) is disposed in the laminate 12. The signal conductor layer 20 (first conductor layer) has an upper main surface (second main surface) and a lower main surface (first main surface). Figure 1 As shown, the signal conductor layer 20 is adhered to the lower main surface of the insulating layer 16c. Therefore, the surface roughness of the upper main surface (second main surface) of the signal conductor layer 20 is greater than the surface roughness of the lower main surface (first main surface) of the signal conductor layer 20. The signal conductor layer 20 has a linear shape extending along the left and right axes.

[0038] like Figure 1 As shown, a ground conductor layer 22 (second conductor layer) is disposed in the laminate 12. The ground conductor layer 22 has an upper main surface and a lower main surface. The ground conductor layer 22 is located above the signal conductor layer 20 and overlaps with the signal conductor layer 20 when viewed in the downward direction. In this embodiment, the ground conductor layer 22 is adhered to the upper main surface of the insulator layer 16b. Therefore, the surface roughness of the lower main surface of the ground conductor layer 22 is greater than the surface roughness of the upper main surface of the ground conductor layer 22. Furthermore, the ground conductor layer 22 covers approximately the entire surface of the upper main surface of the insulator layer 16b. A ground potential is connected to the ground conductor layer 22.

[0039] like Figure 1 As shown, a ground conductor layer 24 is disposed in the laminate 12. The ground conductor layer 24 has an upper main surface and a lower main surface. The ground conductor layer 24 is located below the signal conductor layer 20 and overlaps with the signal conductor layer 20 when viewed in the downward direction. In this embodiment, the ground conductor layer 24 is adhered to the lower main surface of the insulator layer 16d. Therefore, the surface roughness of the upper main surface of the ground conductor layer 24 is greater than the surface roughness of the lower main surface of the ground conductor layer 24. Furthermore, the ground conductor layer 24 covers approximately the entire surface of the lower main surface of the insulator layer 16d. A ground potential is connected to the ground conductor layer 24. The signal conductor layer 20, ground conductor layer 22, and ground conductor layer 24 described above have a stripline structure.

[0040] like Figure 1As shown, a ground conductor layer 25 is disposed in the laminate 12. The ground conductor layer 25 has an upper main surface and a lower main surface. The ground conductor layer 25 is located below the ground conductor layer 22 and above the ground conductor layer 24. In this embodiment, the ground conductor layer 25 is adhered to the lower main surface of the insulating layer 16c. Therefore, the surface roughness of the upper main surface of the ground conductor layer 25 is greater than the surface roughness of the lower main surface of the ground conductor layer 25. Furthermore, the ground conductor layer 25 covers approximately the entire surface of the lower main surface of the insulating layer 16c. However, the ground conductor layer 25 is not in contact with the signal conductor layer 20. Therefore, an opening is provided in the ground conductor layer 25. Moreover, the signal conductor layer 20 is located within the opening. A ground potential is connected to the ground conductor layer 25.

[0041] like Figure 1 As shown, mounting electrode 26a is disposed on laminate 12. Mounting electrode 26a is located at the left end of the upper main surface of insulating layer 16b. When viewed from the downward direction, mounting electrode 26a overlaps with the left end of signal conductor layer 20. When viewed from the downward direction, mounting electrode 26a has a rectangular shape. Mounting electrode 26a is an external terminal for inputting and outputting high-frequency signals. Mounting electrode 26a does not contact ground conductor layer 22. The construction of mounting electrode 26b is symmetrical to that of mounting electrode 26a, therefore its description is omitted.

[0042] like Figure 1 As shown, the interlayer connection conductor v1 is disposed in the laminate 12. Figure 1 as well as Figure 2 As shown, the interlayer connecting conductor v1 electrically connects the mounting electrode 26a and the left end of the signal conductor layer 20. The interlayer connecting conductor v1 extends along the vertical axis through the insulating layers 16b and 16c. The upper end of the interlayer connecting conductor v1 contacts the mounting electrode 26a. The lower end of the interlayer connecting conductor v1 contacts the left end of the signal conductor layer 20. The construction of the interlayer connecting conductor v2 is symmetrical to that of the interlayer connecting conductor v1, therefore its description is omitted.

[0043] like Figure 1 As shown, multiple interlayer connection conductors v3 are disposed in the laminate 12. These interlayer connection conductors v3 are located in front of the signal conductor layer 20. The multiple interlayer connection conductors v3 are arranged in a row along the signal conductor layer 20. Figure 1 As shown, multiple interlayer connecting conductors v3 electrically connect grounding conductor layer 22, grounding conductor layer 24, and grounding conductor layer 25. The multiple interlayer connecting conductors v3 extend through the insulating layers 16b to 16d along the vertical axis. The upper ends of the multiple interlayer connecting conductors v3 are in contact with grounding conductor layer 22. The lower ends of the multiple interlayer connecting conductors v3 are in contact with grounding conductor layer 24. The middle portions of the multiple interlayer connecting conductors v3 are in contact with grounding conductor layer 25.

[0044] like Figure 1As shown, multiple interlayer connection conductors v4 are disposed in the laminate 12. These interlayer connection conductors v4 are located behind the signal conductor layer 20. The multiple interlayer connection conductors v4 are arranged in a row along the signal conductor layer 20. Figure 1 As shown, multiple interlayer connecting conductors v4 electrically connect ground conductor layer 22, ground conductor layer 24, and ground conductor layer 25. The multiple interlayer connecting conductors v4 extend through the insulating layers 16b to 16d along the vertical axis. The upper ends of the multiple interlayer connecting conductors v4 are in contact with ground conductor layer 22. The lower ends of the multiple interlayer connecting conductors v4 are in contact with ground conductor layer 24. The middle portions of the multiple interlayer connecting conductors v4 are in contact with ground conductor layer 25.

[0045] Rectangular openings H1 to H6 are provided in the insulating layer 16a. When viewed from below, opening H1 overlaps with the mounting electrode 26a. Thus, the mounting electrode 26a is exposed from the multilayer substrate 10 to the outside. Opening H2 is located in front of opening H1. A portion of the grounding conductor layer 22 is exposed from the multilayer substrate 10 to the outside via opening H2. Opening H3 is located behind opening H1. A portion of the grounding conductor layer 22 is exposed from the multilayer substrate 10 to the outside via opening H3. Thus, a portion of the grounding conductor layer 22 functions as a grounding terminal. Furthermore, the structures of openings H4 to H6 are symmetrical to those of openings H1 to H3, therefore, their description is omitted.

[0046] The signal conductor layer 20, ground conductor layer 22, ground conductor layer 24, ground conductor layer 25, and mounting electrodes 26a and 26b, as described above, are formed, for example, by etching a metal foil disposed on the upper or lower main surface of the insulating layers 16b to 16d. The metal foil is, for example, copper foil.

[0047] Furthermore, the interlayer connection conductors v1 to v4 are, for example, via conductors. The interlayer connection conductors v1 to v4 are formed by filling conductive paste into the through-holes provided in the insulating layers 16b to 16d, and then curing the conductive paste by heating. The material of the conductive paste is, for example, a mixture of resin and metal.

[0048] In addition, such as Figure 2 As shown, an internal space Sp is provided within the laminate 12. The internal space Sp is a sealed space that is not connected to the space outside the laminate 12. In the lamination direction, the internal space Sp is located between the signal conductor layer 20 (first conductor layer) and the ground conductor layer 22 (second conductor layer). More specifically, a through hole Sp1 is provided in the insulating layer 16b, extending through the insulating layer 16b along the vertical axis. When viewed in the downward direction, the through hole Sp1 has a rectangular shape. The through hole Sp1 extends along the signal conductor layer 20. In this embodiment, when viewed in the downward direction, the through hole Sp1 overlaps with the signal conductor layer 20 and the ground conductor layers 22 and 24.

[0049] A through-hole Sp2 is provided in the insulating layer 16c, extending along the vertical axis through the insulating layer 16c. When viewed in the downward direction, the through-hole Sp2 has a rectangular shape. The through-hole Sp2 extends along the signal conductor layer 20. In this embodiment, when viewed in the downward direction, the through-hole Sp2 overlaps with the signal conductor layer 20 and the ground conductor layers 22 and 24.

[0050] Through-holes Sp1 and Sp2 are interconnected, thereby forming an internal space Sp. Furthermore, when viewed in the stacking direction, at least a portion of the signal conductor layer 20 overlaps with the internal space Sp. The upper main surface (second main surface) of the signal conductor layer 20 has an exposed portion P1 that is exposed in the internal space Sp. Moreover, the surface roughness of the exposed portion P1 is greater than the surface roughness of the lower main surface (first main surface) of the signal conductor layer 20. Similarly, the lower main surface of the ground conductor layer 22 has an exposed portion P2 that is exposed in the internal space Sp. Moreover, the surface roughness of the exposed portion P2 is greater than the surface roughness of the upper main surface of the ground conductor layer 22.

[0051] [Effect]

[0052] High-frequency signals are transmitted in the signal conductor layer 20. To reduce the transmission loss of high-frequency signals, the dielectric loss caused by the insulating layer between the signal conductor layer 20 and the ground conductor layer 22 is reduced by using air, which has a small dielectric loss tangent. Furthermore, air has a low dielectric constant, resulting in a smaller capacitance between the signal conductor layer 20 and the ground conductor layer 22. Therefore, compared to the case without air, the desired characteristic impedance can be obtained even by increasing the linewidth of the signal conductor layer 20. As a result, the conductor loss of the signal conductor layer 20 is reduced, and the overall loss is decreased.

[0053] However, if the insulating layer is made of air, the thermal conductivity decreases, and the heat dissipation of the heat generated in the signal conductor layer 20 becomes smaller. Therefore, by increasing the surface roughness of the air layer side of the signal conductor layer 20 and the ground conductor layer 22, the surface area is increased, thereby increasing the heat dissipation of the signal conductor layer 20 and increasing the heat absorption of the ground conductor layer 22. This allows the heat generated in the signal conductor layer 20 to be efficiently transferred to the outer periphery of the product.

[0054] (First variation)

[0055] Hereinafter, the multilayer substrate 10a involved in the first modified example will be described with reference to the accompanying drawings. Figure 3 This is a cross-sectional view of the multilayer substrate 10a.

[0056] The multilayer substrate 10a differs from the multilayer substrate 10 in that it also includes an electronic component 101. Furthermore, a liquid exists within the internal space Sp, which vaporizes at a temperature between 25°C and 200°C. The liquid is, for example, water. In this modified example, the ground conductor layer 22 is the first conductor layer. The electronic component 101 is mounted on the upper main surface of the laminate 12. When viewed downwards, the electronic component 101 overlaps with the left end of the internal space Sp. The electronic component 101 is a heat-generating element. The electronic component 101 is, for example, an integrated circuit (IC). The heat generated by the electronic component 101 is transferred downwards to the laminate 12. Moreover, the heat generated by the electronic component 101 is transferred to the left side of the ground conductor layer 22. Because water is present in the internal space Sp, the water evaporates from the left side of the ground conductor layer 22.

[0057] Water vapor travels to the right in the internal space Sp. During this time, the water vapor is cooled. As a result, the water vapor turns into water at the right end of the internal space Sp and adheres to the grounding conductor layer 22.

[0058] Here, the surface roughness of the lower main surface (second main surface) of the ground conductor layer 22 (first conductor layer) is greater than the surface roughness of the upper main surface (first main surface) of the ground conductor layer 22 (first conductor layer). Therefore, the lower main surface of the ground conductor layer 22 functions as a wick. Consequently, water travels to the left along the lower main surface of the ground conductor layer 22. In this way, the ground conductor layer 22 and its internal space Sp function as heat pipes. As a result, improved heat dissipation of the multilayer substrate 10a is achieved. The other structures of the multilayer substrate 10a are the same as those of the multilayer substrate 10, and therefore descriptions are omitted. The multilayer substrate 10a achieves the same effects as the multilayer substrate 10.

[0059] Furthermore, in the multilayer substrate 10a, the insulating layers 16a to 16e are made of resin with a water absorption rate of 0.1% or less. Because the insulating layers 16a to 16e have a low water absorption rate, water within the internal space Sp can be prevented from being absorbed by the insulating layers 16a to 16e and released outside the laminate 12.

[0060] (Second variation)

[0061] The multilayer substrate 10b of the second modified example will be described below with reference to the accompanying drawings. Figure 4 This is a cross-sectional view of the multilayer substrate 10b.

[0062] The multilayer substrate 10b differs from the multilayer substrate 10 in the following aspects.

[0063] • It has multiple internal spaces (Sp).

[0064] • The signal conductor layer 20 and the ground conductor layer 25 are adhered to the lower main surface of the insulating layer 16b.

[0065] Multiple internal spaces Sp are disposed in the insulating layer 16b. When viewed from below, the multiple internal spaces Sp overlap with the signal conductor layer 20. The multiple internal spaces Sp are arranged in a row along the signal conductor layer 20. The other structures of the multilayer substrate 10b are the same as those of the multilayer substrate 10, and therefore are omitted from the description. The multilayer substrate 10b can achieve the same functional effects as the multilayer substrate 10.

[0066] According to the multilayer substrate 10b, a portion of the upper main surface of the signal conductor layer 20 is supported by the insulating layer 16b. This suppresses deviations of the signal conductor layer 20 from its designed position. Furthermore, heat generated by the signal conductor layer 20 can be transferred upwards via the insulating layer 16b. This improves the heat dissipation of the multilayer substrate 10b. Therefore, heat dissipation can be ensured even without roughening the upper main surface of the signal conductor layer 20.

[0067] (3rd variation)

[0068] The multilayer substrate 10c of the third modified example will be described below with reference to the accompanying drawings. Figure 5 This is a cross-sectional view of the multilayer substrate 10c.

[0069] The multilayer substrate 10c differs from the multilayer substrate 10b in the following aspects.

[0070] • Insulator layer 16e is located between insulating layer 16d and insulating layer 16f.

[0071] • The grounding conductor layer 24 is adhered to the lower main surface of the insulating layer 16e.

[0072] • It has multiple internal spaces (Sp3).

[0073] Multiple internal spaces Sp3 are disposed in the insulating layer 16e. When viewed from the downward direction, the multiple internal spaces Sp3 overlap with the signal conductor layer 20. The multiple internal spaces Sp3 are arranged in a row along the signal conductor layer 20. The other structures of the multilayer substrate 10c are the same as those of the multilayer substrate 10b, so description is omitted. The multilayer substrate 10c can achieve the same functional effect as the multilayer substrate 10.

[0074] (4th variation)

[0075] The multilayer substrate 10d involved in the fourth modified example will be described below with reference to the accompanying drawings. Figure 6 This is a cross-sectional view of a multilayer substrate (10d).

[0076] The multilayer substrate 10d differs from multilayer substrate 10 in that it also includes ground conductor layers 23 and 29, mounting electrodes 26a to 26f, and a signal conductor layer 27. Mounting electrodes 26a to 26c are attached to the upper main surface of insulating layer 16a. Mounting electrodes 26d and 26e are attached to the lower main surface of insulating layer 16f. Ground conductor layer 23 is attached to the upper main surface of insulating layer 16b. Signal conductor layer 27 is attached to the upper main surface of insulating layer 16c. Ground conductor layer 29 is attached to the lower main surface of insulating layer 16e.

[0077] Interlayer connection conductor v11 electrically connects mounting electrode 26a and ground conductor layer 23. Interlayer connection conductor v12 electrically connects mounting electrode 26b and ground conductor layer 23. Interlayer connection conductor v13 electrically connects mounting electrode 26c and ground conductor layer 23. Interlayer connection conductors v14 and v15 electrically connect ground conductor layer 22 and ground conductor layer 23. Interlayer connection conductor v16 electrically connects mounting electrode 26d and ground conductor layer 29. Interlayer connection conductor v17 electrically connects mounting electrode 26e and ground conductor layer 29. Interlayer connection conductor v18 electrically connects mounting electrode 26f and ground conductor layer 29. The other structures of multilayer substrate 10d are the same as those of multilayer substrate 10, and therefore descriptions are omitted. Multilayer substrate 10d can achieve the same functional effects as multilayer substrate 10.

[0078] In the multilayer substrate 10d, interlayer connecting conductors v14 and v15 are connected to the ground conductor layer 22. As a result, heat from the ground conductor layer 22 is released into the atmosphere via the interlayer connecting conductors v11 to v15 and the mounting electrodes 26a to 26c.

[0079] In the multilayer substrate 10d, the signal conductor layer 27 is located at the upper right of the internal space Sp. Heat is dissipated via the signal conductor layer 27.

[0080] Mounting electrodes 26a to 26f are provided in the multilayer substrate 10d. As a result, heat can be transferred to the mother substrate via the mounting electrodes 26a to 26f.

[0081] (5th variation)

[0082] The multilayer substrate 10e of the fifth modified example will be described below with reference to the accompanying drawings. Figure 7 This is a cross-sectional view of the multilayer substrate 10e.

[0083] The multilayer substrate 10e differs from multilayer substrate 10 in that it has internal spaces Spa and Spb provided above and below the signal conductor layer 20. More specifically, the signal conductor layer 20 is located on the lower main surface of the insulating layer 16b. Furthermore, the internal space Spa is provided in the insulating layer 16b, and the internal space Spb is provided in the insulating layer 16c. This further reduces the transmission loss of the signal conductor layer 20. The other structures of multilayer substrate 10e are the same as those of multilayer substrate 10, and therefore descriptions are omitted. Multilayer substrate 10e achieves the same functional effects as multilayer substrate 10.

[0084] (Electronic devices)

[0085] The structure of electronic device 1 will now be described with reference to the accompanying drawings. Figure 8 This is a cross-sectional view of an electronic device 1 having a multilayer substrate 10.

[0086] Electronic device 1 includes a multilayer substrate 10 and a housing 100. The housing 100 houses the multilayer substrate 10. Electronic device 1 is a wireless communication terminal such as a smartphone. Furthermore, the multilayer substrate 10 is bent. In addition, if the multilayer substrate 10 is in contact with the housing 100, heat is efficiently transferred from the heat source to the housing 100, resulting in high heat dissipation effect.

[0087] (Other implementation methods)

[0088] The multilayer substrates involved in this utility model are not limited to multilayer substrates 10, 10a to 10e, and can be modified within the scope of its intent. In addition, the structures of multilayer substrates 10, 10a to 10e can be arbitrarily combined.

[0089] Furthermore, the surface roughness of the exposed portion P1 only needs to be greater than the surface roughness of the lower main surface of the signal conductor layer 20. Therefore, the surface roughness of the portion of the upper main surface of the signal conductor layer 20 other than the exposed portion P1 can also be no greater than the surface roughness of the lower main surface of the signal conductor layer 20.

[0090] Alternatively, the entire upper and lower surfaces of the internal space Sp can be covered by a conductor layer.

[0091] In addition, the internal space Sp may not be a closed space that is not connected to the space outside the stacked body 12.

[0092] This utility model has the following structure.

[0093] (1) A multilayer substrate, characterized in that,

[0094] The multilayer substrate has a laminate and a first conductor layer.

[0095] The laminate has a structure in which multiple insulating layers are stacked in the stacking direction.

[0096] The first conductor layer is disposed in the laminate.

[0097] An internal space is provided within the stacked body.

[0098] The first conductor layer has a first main surface and a second main surface.

[0099] The second main surface has an exposed portion that is visible in the interior space.

[0100] The surface roughness of the exposed portion is greater than the surface roughness of the first main surface.

[0101] (2) The multilayer substrate according to (1) is characterized in that,

[0102] The surface roughness of the second principal surface is greater than that of the first principal surface.

[0103] (3) The multilayer substrate according to (1) or (2) is characterized in that,

[0104] The first conductor layer is a signal conductor layer.

[0105] At least a portion of the signal conductor layer overlaps with the internal space when viewed in the stacking direction.

[0106] (4) The multilayer substrate according to any one of (1) to (3), characterized in that,

[0107] The internal space contains a liquid that vaporizes at a temperature above 25 degrees Celsius and below 200 degrees Celsius.

[0108] (5) The multilayer substrate according to any one of (1) to (4), characterized in that,

[0109] The material of the plurality of insulating layers is a resin with a water absorption rate of less than 0.1%.

[0110] (6) The multilayer substrate according to any one of (1) to (5), characterized in that,

[0111] The coefficient of thermal expansion of the plurality of insulating layers in the stacking direction is greater than the coefficient of thermal expansion of the plurality of insulating layers in the orthogonal direction to the stacking direction.

[0112] (7) The multilayer substrate according to any one of (1) to (6), characterized in that,

[0113] The material of the plurality of insulating layers is a liquid crystal polymer.

[0114] (8) The multilayer substrate according to any one of (1) to (7), characterized in that,

[0115] The adjacent insulating layers of the plurality of insulating layers are fused together in the stacking direction.

[0116] (9) The multilayer substrate according to (1) is characterized in that,

[0117] The multilayer substrate also includes a second conductor layer.

[0118] The second conductor layer is disposed in the laminate.

[0119] In the stacking direction, the internal space is located between the first conductor layer and the second conductor layer.

[0120] (10) The multilayer substrate according to any one of (1) to (9), characterized in that,

[0121] The interior space is a sealed space that is not connected to the space outside the stacked body.

[0122] (11) An electronic device, characterized in that,

[0123] The electronic device comprises a multilayer substrate as described in any one of (1) to (10).

[0124] Explanation of reference numerals in the attached figures

[0125] 1: Electronic devices

[0126] 10, 10a~10e: Multilayer substrates

[0127] 12: Layered bodies

[0128] 16a-16f: Insulating layer

[0129] 20, 27: Signal conductor layer

[0130] 22-25: Grounding conductor layer

[0131] 26a~26f: Install electrodes

[0132] 27: Signal Conductor Layer

[0133] 29: Grounding conductor layer

[0134] 100: Casing

[0135] 101: Electronic Components

[0136] P1, P2: Exposed parts

[0137] Sp: Internal space

[0138] Sp1: Through hole

[0139] Sp2: Through hole

[0140] v1-v4, v11-v18: Interlayer connection conductors.

Claims

1. A multilayer substrate, characterized in that, The multilayer substrate has a laminate and a first conductor layer. The laminate has a structure in which multiple insulating layers are stacked in the stacking direction. The first conductor layer is disposed in the laminate. An internal space is provided within the stacked body. The first conductor layer has a first main surface and a second main surface. The second main surface has an exposed portion exposed in the internal space and a portion adhered to the plurality of insulating layers. The surface roughness of the second principal surface is greater than that of the first principal surface.

2. The multilayer substrate according to claim 1, characterized in that, The first conductor layer is a signal conductor layer. At least a portion of the signal conductor layer overlaps with the internal space when viewed in the stacking direction.

3. The multilayer substrate according to claim 1 or 2, characterized in that, The internal space contains a liquid that vaporizes at a temperature above 25 degrees Celsius and below 200 degrees Celsius.

4. The multilayer substrate according to claim 1 or 2, characterized in that, The material of the plurality of insulating layers is a resin with a water absorption rate of less than 0.1%.

5. The multilayer substrate according to claim 1 or 2, characterized in that, The coefficient of thermal expansion of the plurality of insulating layers in the stacking direction is greater than the coefficient of thermal expansion of the plurality of insulating layers in the orthogonal direction to the stacking direction.

6. The multilayer substrate according to claim 1 or 2, characterized in that, The material of the plurality of insulating layers is a liquid crystal polymer.

7. The multilayer substrate according to claim 1 or 2, characterized in that, The adjacent insulating layers of the plurality of insulating layers are fused together in the stacking direction.

8. The multilayer substrate according to claim 1, characterized in that, The multilayer substrate also includes a second conductor layer. The second conductor layer is disposed in the laminate. In the stacking direction, the internal space is located between the first conductor layer and the second conductor layer.

9. The multilayer substrate according to claim 1 or 2, characterized in that, The interior space is a sealed space that is not connected to the space outside the stacked body.

10. An electronic device, characterized in that, The electronic device comprises a multilayer substrate as described in any one of claims 1 to 9.

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