Multilayer substrate

Abstract

Provided is a multilayer substrate provided with a laminate having a structure in which a plurality of insulator layers are laminated along a Z-axis, the laminate having a positive main surface and a negative main surface positioned nearer to the negative side of the Z-axis than the positive main surface, a protective layer covering at least a part of the positive main surface, and one or more internal conductors arranged between the protective layer and the positive main surface, the material of the protective layer is different from the material of the plurality of insulator layers, one or more internal conductors are provided inside the laminate, overlap the edge of the protective layer when viewed in the Z-axis negative direction, and extend along the edge of the protective layer, and protrusions are provided on the positive main surface of the laminate, and extend along the edge of the protective layer when viewed in the Z-axis negative direction. The projection overlaps with an edge of the protective layer and the one or more internal conductors, has a line shape extending along the edge of the protective layer, and has a thickness of the protective layer at a portion where the protective layer overlaps with the projection when viewed in the Z-axis negative direction, the thickness of the protective layer at a portion where the protective layer does not overlap with the projection, and a thickness of the protective layer at a portion where the projection does not overlap with the projection when viewed in the Z-axis negative direction. The length of the line-shaped protrusion is longer than the width of the line-shaped protrusion.

Description

Technical Field

[0001] This invention 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, there is a known method for manufacturing a printed wiring substrate as described in Patent Document 1. In this method, the aim is to reduce the undercut of the resist layer. The undercut of the resist layer will be described below.

[0003] The photoresist layer is formed through the following steps: A photosensitive photoresist is applied to a substrate. The photosensitive photoresist is cured by irradiating light through a mask. Finally, the uncured photosensitive photoresist is removed. Here, near the edge of the mask, a shaded area is created during exposure. In this shaded area, the photosensitive photoresist is not adequately irradiated with light. Therefore, the photosensitive photoresist does not cure sufficiently in the shaded area. As a result, as in Patent Document 1... Figure 2 As shown in (b), the end face of the resist layer is obliquely inclined relative to the vertical direction. This phenomenon of the end face of the resist layer being obliquely inclined relative to the vertical direction is called undercut. If such undercut occurs, the resist layer is easily peeled off from the substrate.

[0004] Therefore, as described in the manufacturing method of the printed wiring substrate in Patent Document 1, an invention was proposed to reduce the undercut of the resist layer. As a result, in the manufacturing method of the printed wiring substrate described in Patent Document 1, the peeling of the resist layer is suppressed.

[0005] Prior art literature

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2009-267173 (see reference) Figure 2 (b) Utility Model Content

[0008] Problems to be solved by utility models

[0009] As mentioned above, a multilayer substrate is needed that can suppress the peeling of the resist layer.

[0010] Therefore, the purpose of this invention is to provide a new multilayer substrate capable of suppressing the peeling of the protective layer, as well as a method for manufacturing the multilayer substrate.

[0011] Technical solutions for solving the problem

[0012] One embodiment of this utility model relates to a multilayer substrate comprising a laminate, a protective layer, and one or more internal conductors.

[0013] The laminate has a structure in which multiple insulating layers are stacked along the Z-axis.

[0014] The laminate has a positive principal plane and a negative principal plane located on the negative side of the Z-axis, which is closer to the positive principal plane.

[0015] The protective layer covers at least a portion of the main surface.

[0016] The material of the protective layer is different from the material of the plurality of insulating layers.

[0017] One or more internal conductors are disposed inside the laminate and, when viewed in the negative Z-axis direction, overlap with the edge of the protective layer and extend along the edge of the protective layer when viewed in the negative Z-axis direction.

[0018] A protrusion is provided on the main surface of the laminate.

[0019] Viewed in the negative direction of the Z-axis, the protrusion overlaps with the edge of the protective layer and the one or more inner conductors, and has a linear shape extending along the edge of the protective layer.

[0020] When viewed in the negative Z-axis direction, the thickness of the protective layer at the portion where it overlaps with the protrusion is less than the thickness of the protective layer at the portion where it does not overlap with the protrusion when viewed in the negative Z-axis direction.

[0021] When viewed in the negative direction of the Z-axis, the length of the linear protrusion is longer than the width of the linear protrusion.

[0022] One aspect of this utility model relates to a multilayer substrate comprising a laminate, a protective layer, and multiple internal conductors.

[0023] The laminate has a structure in which multiple insulating layers are stacked along the Z-axis.

[0024] The laminate has a positive principal plane and a negative principal plane located on the negative side of the Z-axis, which is closer to the positive principal plane.

[0025] The protective layer covers a portion of the main surface.

[0026] The material of the protective layer is different from the material of the plurality of insulating layers.

[0027] The plurality of internal conductors are disposed inside the laminate and, when viewed in the negative Z-axis direction, overlap with the edge of the protective layer and are arranged along the edge of the protective layer when viewed in the negative Z-axis direction.

[0028] A protrusion is provided on the main surface of the laminate.

[0029] Viewed in the negative direction of the Z-axis, the protrusion overlaps with the edge of the protective layer and the plurality of internal conductors, and has a linear shape extending along the edge of the protective layer.

[0030] When viewed in the negative direction of the Z-axis, the thickness of the protective layer at the portion where it overlaps with the protrusion is less than the thickness of the protective layer at the portion where it does not overlap with the protrusion when viewed in the negative direction of the Z-axis.

[0031] One aspect of this utility model relates to a method for manufacturing a multilayer substrate, which includes:

[0032] The pressing process, pressing laminates; and

[0033] The protective layer forming process involves forming a protective layer on the laminated body after pressing.

[0034] The laminate has a structure in which multiple insulating layers are stacked along the Z-axis.

[0035] The laminate has a positive principal plane and a negative principal plane located on the negative side of the Z-axis, which is closer to the positive principal plane.

[0036] The protective layer covers at least a portion of the main surface.

[0037] The material of the protective layer is different from the material of the plurality of insulating layers.

[0038] One or more internal conductors are disposed inside the laminate.

[0039] During the crimping process, a protrusion is formed on the main surface of the laminate, in the portion overlapping with one or more internal conductors.

[0040] In the protective layer forming process, the protective layer is formed on the positive main surface such that when viewed in the negative direction of the Z-axis, the edge of the protective layer overlaps with the protrusion.

[0041] One aspect of this utility model relates to a method for manufacturing a multilayer substrate, which includes:

[0042] The pressing process involves pressing laminated bodies.

[0043] The protective layer forming process involves forming a protective layer on the laminated body after pressing; and

[0044] The cutting process involves cutting the laminated body with the protective layer formed thereon.

[0045] The laminate has a structure in which multiple insulating layers are stacked along the Z-axis.

[0046] The laminate has a positive principal plane and a negative principal plane located on the negative side of the Z-axis, which is closer to the positive principal plane.

[0047] The protective layer covers at least a portion of the main surface.

[0048] The material of the protective layer is different from the material of the plurality of insulating layers.

[0049] One or more internal conductors are disposed inside the laminate.

[0050] During the crimping process, a protrusion is formed on the main surface of the laminate, in the portion overlapping with one or more internal conductors.

[0051] In the protective layer forming process, the protective layer is formed on the positive main surface such that, when viewed in the negative direction of the Z-axis, the protective layer covers the protrusion.

[0052] In the cutting process, the laminate is cut such that when viewed in the negative direction of the Z-axis, the protrusion is segmented.

[0053] Utility Model Effect

[0054] According to the multilayer substrate and the manufacturing method of the multilayer substrate involved in this utility model, the peeling of the protective layer can be suppressed. Attached Figure Description

[0055] Figure 1 This is an exploded perspective view of the multilayer substrate 10.

[0056] Figure 2 These are cross-sectional views and top views of the multilayer substrate 10.

[0057] Figure 3 This is a front view of the multilayer substrate 10 in use.

[0058] Figure 4 This is a cross-sectional view of the multilayer substrate 10 during manufacturing.

[0059] Figure 5 This is a cross-sectional view of the multilayer substrate 10 during manufacturing.

[0060] Figure 6 These are cross-sectional views and top views of the multilayer substrate 10a.

[0061] Figure 7 This is a cross-sectional view of the multilayer substrate 10b.

[0062] Figure 8 This is a cross-sectional view of the multilayer substrate 10c.

[0063] Figure 9These are cross-sectional views and top views of the multilayer substrate 10d.

[0064] Figure 10 These are cross-sectional views and top views of the multilayer substrate 10e.

[0065] Figure 11 This is a cross-sectional view of the multilayer substrate 10f.

[0066] Figure 12 This is a rear view of the multilayer substrate 10f in use.

[0067] Figure 13 This is a cross-sectional view of the multilayer substrate 10f during manufacturing.

[0068] Figure 14 This is a cross-sectional view of the multilayer substrate 10f during manufacturing.

[0069] Figure 15 This is a cross-sectional view of the multilayer substrate 10f during manufacturing.

[0070] Figure 16 This is a top view of the mother substrate 100.

[0071] Explanation of reference numerals in the attached figures

[0072] 10, 10a~10f: Multilayer substrates

[0073] 12: Layered bodies

[0074] 16a~16e: Insulating layer

[0075] 18a, 18b: Protective layer

[0076] 20: Signal Conductor Layer

[0077] 22: First grounding conductor layer

[0078] 24: Second grounding conductor layer

[0079] 26a, 26b: Install electrodes

[0080] 28a, 28b, 30a, 30b, 32a, 32b, 34a, 36a, 38a: Internal conductors

[0081] 40a: Surface conductor

[0082] A1: Interval 1

[0083] A2: Second Interval

[0084] E: Fate

[0085] P1~P6: Protrusions

[0086] h1~h6: Openings

[0087] v10: First connecting conductor

[0088] v12: Second connecting conductor

[0089] v14: Third connecting conductor

[0090] v16: 4th connecting conductor. Detailed Implementation

[0091] (Implementation Method)

[0092] [Structure of multilayer substrates]

[0093] 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 These are cross-sectional views and top views of the multilayer substrate 10. Figure 2 In, it is shown Figure 1 The cross-section at point AA. Figure 3 This is a front view of the multilayer substrate 10 in use. Additionally, in Figure 1 In the text, only representative interlayer connecting conductors v3 and v4 among the multiple interlayer connecting conductors v3 and v4 are marked with reference labels.

[0094] In this specification, directions are defined as follows: The stacking direction of the laminate 12 of the multilayer substrate 10 is defined as the up-down direction. Furthermore, the up-down direction coincides with the Z-axis direction. The up direction is the positive direction of the Z-axis. The down direction is the negative direction of the Z-axis. Furthermore, the direction in which the signal conductor layer 20 of the multilayer substrate 10 extends is defined as the left-right direction. Furthermore, viewed in the up-down direction, the linewidth direction of the signal conductor layer 20 is defined as the front-back direction. The up-down direction, the front-back direction, and the left-right direction are orthogonal to each other. Additionally, the up and down directions of the up-down direction, the left and right directions of the left-right direction, and the front and back directions of the front-back direction can be interchanged.

[0095] 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 front end of X. Rear end of X refers to the rear end of X. Left end of X refers to the left end of X. Right end of X refers to the right end of X. Upper end of X refers to the upper end of X. Lower end of X refers to the lower end of X. 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.

[0096] First, refer to Figure 1 The structure of the multilayer substrate 10 will be explained below. The multilayer substrate 10 transmits high-frequency signals. The multilayer substrate 10 is used to electrically connect two circuits in electronic devices such as smartphones. For example... Figure 1 As shown, the multilayer substrate 10 includes a laminate 12, protective layers 18a and 18b, a signal conductor layer 20, a first ground conductor layer 22, a second ground conductor layer 24, mounting electrodes 26a and 26b, internal conductors 28a, 28b, 30a, 30b, 32a and 32b, interlayer connection conductors v1 and v2, and multiple interlayer connection conductors v3 and v4.

[0097] The laminate 12 has a plate shape. Therefore, the laminate 12 has an upper principal surface (positive principal surface) and a lower principal surface (negative principal surface) located below the upper principal surface (positive principal surface) (on the negative side of the Z-axis). The upper and lower principal surfaces of the laminate 12 have rectangular shapes with long sides extending along the left and right axes. Therefore, the length of the laminate 12 in the left-right direction is longer than the length of the laminate 12 in the front-back direction. The laminate 12 is flexible.

[0098] like Figure 1 As shown, the laminate 12 has a structure in which insulating layers 16a to 16d are stacked along the vertical axis (Z-axis). The insulating layers 16a to 16d are arranged sequentially from top to bottom. The material of the insulating layers 16a to 16d is, for example, a thermoplastic resin. The thermoplastic resin is, for example, a liquid crystal polymer. Furthermore, the insulating layers 16a to 16d are fused together with adjacent layers.

[0099] High-frequency signals are transmitted in the signal conductor layer 20. For example... Figure 1 As shown, the signal conductor layer 20 is located on the upper main surface of the insulating layer 16c. The signal conductor layer 20 has a linear shape extending along the left and right axes.

[0100] like Figure 1 As shown, a first ground conductor layer 22 is disposed in the laminate 12. The first ground conductor layer 22 is located above the signal conductor layer 20 and overlaps with it when viewed downwards. In this embodiment, the first ground conductor layer 22 is located on the upper main surface of the insulating layer 16a. Furthermore, the first ground conductor layer 22 covers approximately the entire upper main surface of the insulating layer 16a. A ground potential is connected to the first ground conductor layer 22.

[0101] like Figure 1 As shown, a second ground conductor layer 24 is disposed in the laminate 12. The second ground conductor layer 24 is located below the signal conductor layer 20 and overlaps with it when viewed downwards. In this embodiment, the second ground conductor layer 24 is located on the lower main surface of the insulator layer 16d. Furthermore, the second ground conductor layer 24 covers approximately the entire lower main surface of the insulator layer 16d. A ground potential is connected to the second ground conductor layer 24. The signal conductor layer 20, the first ground conductor layer 22, and the second ground conductor layer 24, as described above, have a stripline structure.

[0102] like Figure 1 As shown, mounting electrode 26a is located on the upper main surface (positive main surface) of the laminate 12. More specifically, mounting electrode 26a is located at the left end of the upper main surface of the insulating layer 16a. Viewed vertically, mounting electrode 26a overlaps with the left end of the signal conductor layer 20. Viewed vertically, 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 the first ground conductor layer 22. The construction of mounting electrode 26b is symmetrical to that of mounting electrode 26a, therefore its description is omitted.

[0103] like 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 penetrates the insulating layers 16a and 16b in the vertical direction. The upper end of the interlayer connecting conductor v1 is connected to the mounting electrode 26a. The lower end of the interlayer connecting conductor v1 is connected to the left end of the signal conductor layer 20. The construction of the mounting electrode 26b and the interlayer connecting conductor v2 is symmetrical to that of the mounting electrode 26a and the interlayer connecting conductor v1, therefore, description is omitted.

[0104] Multiple interlayer connection conductors v3 electrically connect the first ground conductor layer 22 and the second ground conductor layer 24. More specifically, as... Figure 1As shown, multiple interlayer connecting conductors v3 are located ahead of the signal conductor layer 20. The multiple interlayer connecting conductors v3 are arranged in a row in the left-right direction. The multiple interlayer connecting conductors v3 penetrate the insulating layers 16a to 16d in the vertical direction. The upper ends of the multiple interlayer connecting conductors v3 are connected to the first grounding conductor layer 22. The lower ends of the multiple interlayer connecting conductors v3 are connected to the second grounding conductor layer 24.

[0105] Multiple interlayer connection conductors v4 electrically connect the first ground conductor layer 22 and the second ground conductor layer 24. More specifically, as... Figure 1 As shown, multiple interlayer connecting conductors v4 are located behind the signal conductor layer 20. The multiple interlayer connecting conductors v4 are arranged in a row in the left-right direction. The multiple interlayer connecting conductors v4 penetrate the insulating layers 16a to 16d in the vertical direction. The upper ends of the multiple interlayer connecting conductors v4 are connected to the first grounding conductor layer 22. The lower ends of the multiple interlayer connecting conductors v4 are connected to the second grounding conductor layer 24.

[0106] The signal conductor layer 20, the first ground conductor layer 22, the second ground conductor layer 24, the interlayer connecting conductors v1 and v2, the multiple interlayer connecting conductors v3 and the multiple interlayer connecting conductors v4 are one or more circuit conductors that form an electrical circuit.

[0107] The protective layer 18a covers a portion of the upper main surface (positive main surface of the Z-axis) of the laminate 12. Thus, the protective layer 18a protects the first ground conductor layer 22. However, the protective layer 18a has rectangular openings h1 to h6. Therefore, when viewed in the downward direction (negative direction of the Z-axis), the protective layer 18a has six annular edges E. When viewed in the vertical direction, opening h1 overlaps with the mounting electrode 26a. That is, when viewed in the downward direction (negative direction of the Z-axis), the mounting electrode 26a is located in the area surrounded by the annular edges E. Thus, the mounting electrode 26a is exposed to the outside from the multilayer substrate 10. Opening h2 is located before opening h1. A portion of the first ground conductor layer 22 is exposed to the outside from the multilayer substrate 10 via opening h2. Opening h3 is located after opening h1. A portion of the first ground conductor layer 22 is exposed to the outside from the multilayer substrate 10 via opening h3. Thus, a portion of the first ground 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, so their descriptions are omitted.

[0108] The protective layer 18b covers the lower main surface of the laminate 12. Thus, the protective layer 18b protects the second grounding conductor layer 24.

[0109] The materials of the protective layers 18a and 18b described above are different from those of the insulating layers 16a to 16d. The protective layers 18a and 18b are what is known as solder resist. The solder resist is made of alkali-soluble resin, photopolymerization initiator, epoxy resin used to improve heat resistance, and compositions formulated from inorganic powders, etc.

[0110] Internal conductors 28a, 30a, and 32a are disposed inside the laminate 12. In this embodiment, internal conductors 28a, 30a, and 32a are located at the left end of the upper main surface of the insulating layer 16b. Figure 2 As shown, when viewed in the downward direction (negative Z-axis direction), the internal conductors 28a, 30a, and 32a overlap with the edge E of the protective layer 18a. Furthermore, when viewed in the downward direction (negative Z-axis direction), the internal conductors 28a, 30a, and 32a extend along the edge E of the protective layer 18a. In this embodiment, when viewed in the downward direction (negative Z-axis direction), the internal conductors 28a, 30a, and 32a each have a ring shape along the ring shape of the edge E of the openings h1, h2, and h3 of the protective layer 18a. Therefore, when viewed in the downward direction, the internal conductors 28a, 30a, and 32a have a rectangular ring shape. The structures of the internal conductors 28b, 30b, and 32b are symmetrical to the structures of the internal conductors 28a, 30a, and 32a, and therefore their description is omitted. The internal conductors 28a, 28b, 30a, 30b, 32a, and 32b described above are not electrically connected in series with more than one circuit conductor. Therefore, internal conductors 28a, 28b, 30a, 30b, 32a, and 32b do not transmit high-frequency signals, are not connected to ground potential, and are not connected to power supply potential. The potentials of internal conductors 28a, 28b, 30a, 30b, 32a, and 32b are floating potentials.

[0111] The signal conductor layer 20, the first ground conductor layer 22, the second ground conductor layer 24, the mounting electrodes 26a and 26b, and the internal conductors 28a, 28b, 30a, 30b, 32a, and 32b, as described above, are formed, for example, by etching a metal foil disposed on the upper or lower main surface of the insulating layers 16a to 16d. The metal foil is, for example, copper foil. Thus, the signal conductor layer 20, the first ground conductor layer 22, the second ground conductor layer 24, the mounting electrodes 26a and 26b (at least a portion of which are circuit conductors), and the internal conductors 28a, 28b, 30a, 30b, 32a, and 32b are metal foils disposed on the main surface of the insulating layers 16a to 16d.

[0112] Furthermore, the interlayer connection conductors v1 to v4 are, for example, via conductors. These via conductors are fabricated by forming through holes in the insulating layers 16a to 16d, filling the through holes with conductive paste, and then sintering the conductive paste. The materials for the interlayer connection conductors v1 to v4 are mixtures of resin and metal.

[0113] In addition, such as Figure 2 As shown, protrusions P1 to P6 are provided on the upper main surface (front main surface) of the laminate 12. Figure 2 In the diagram, only protrusion P1 is shown. Protrusions P1 to P3 are located at the left end of the upper main surface of the insulating layer 16a. Protrusions P4 to P6 are located at the right end of the upper main surface of the insulating layer 16a. Viewed downwards (negative Z-axis direction), protrusions P1 to P6 overlap with the edges E of the openings h1 to h6 of the protective layer 18a and the internal conductors 28a, 28b, 30a, 30b, 32a, and 32b, respectively.

[0114] Furthermore, protrusions P1 to P6 each have a linear shape extending along the edges E of the inner conductors 28a, 28b, 30a, 30b, 32a, 32b and the openings h1 to h6 of the protective layer 18a. Therefore, when viewed in the downward direction (negative Z-axis direction), protrusions P1 to P6 each have an annular shape along the edges E of the annular shapes of the inner conductors 28a, 28b, 30a, 30b, 32a, 32b and the openings h1 to h6. Consequently, when viewed in the downward direction (negative Z-axis direction), the length of the linear protrusions P1 to P6 is longer than their width. By providing the protrusions P1 to P6 as described above, when viewed in the downward direction (negative direction of the Z-axis), the thickness T1 of the protective layer 18a overlapping with the protrusions P1 to P6 is less than the thickness T2 of the protective layer 18a not overlapping with the protrusions P1 to P6 when viewed in the downward direction (negative direction of the Z-axis).

[0115] The multilayer substrate 10 described above is flexible. Therefore, as... Figure 3 As shown, the multilayer substrate 10 is bendable. Specifically, the multilayer substrate 10 has a first section A1 and a second section A2. Protrusions P1 to P3 are located in the second section A2. When viewed in the forward direction (the positive direction of the Y-axis orthogonal to the Z-axis), the second section A2 is bendable.

[0116] [Manufacturing method of multilayer substrate 10]

[0117] Next, the manufacturing method of the multilayer substrate 10 will be described with reference to the accompanying drawings. Figure 4 as well as Figure 5 This is a cross-sectional view of the multilayer substrate 10 during manufacturing.

[0118] First, prepare insulating layers 16a to 16d with metal foil attached to the upper or lower main surface. Then, by patterning the metal foil, form signal conductor layer 20, first ground conductor layer 22, second ground conductor layer 24, mounting electrodes 26a and 26b, and internal conductors 28a, 28b, 30a, 30b, 32a, and 32b.

[0119] Next, as Figure 4 As shown, insulating layers 16a to 16d are arranged sequentially from top to bottom. Thus, internal conductors 28a, 28b, 30a, 30b, 32a, and 32b are disposed inside the laminate 12. Then, the laminate containing the insulating layers 16a to 16d is crimped (crimping process). In the crimping process, isotropic pressing is used. Furthermore, in the hot-pressing process, heat treatment is also performed. Figure 5 As shown, the insulating layer 16a is pushed upward by the internal conductors 28a, 28b, 30a, 30b, 32a, and 32b. As a result, during the crimping process, protrusions P1 to P6 are formed on the upper main surface (positive main surface) of the laminate 12 in the portions overlapping with the internal conductors 28a, 28b, 30a, 30b, 32a, and 32b, respectively.

[0120] Next, as Figure 2 As shown, protective layers 18a and 18b are formed on the laminated body 12 after lamination (protective layer formation process). In the protective layer formation process, protective layer 18a is formed on the upper main surface (positive main surface) of the laminated body 12, such that when viewed in the downward direction (negative direction of the Z-axis), the edge E of protective layer 18a overlaps with protrusions P1 to P6. Specifically, by screen printing, a photosensitive material of protective layers 18a and 18b is applied to the entire surface of the upper main surface and the entire surface of the lower main surface of the laminated body 12. At this time, the thickness T1 of the material of protective layer 18a overlapping with protrusions P1 to P6 when viewed in the downward direction (negative direction of the Z-axis) is less than the thickness T2 of the material of protective layer 18a not overlapping with protrusions P1 to P6 when viewed in the downward direction (negative direction of the Z-axis). Then, the material of protective layers 18a and 18b is exposed. Finally, the uncured material of protective layers 18a and 18b is removed. Thus, a protective layer 18a is formed, with the edge E of the protective layer 18a overlapping the protrusions P1 to P6. After the above process, the multilayer substrate 10 is completed.

[0121] [Effect]

[0122] According to the multilayer substrate 10, peeling of the protective layer 18a can be suppressed. More specifically, the internal conductor 28a is disposed inside the laminate 12, and overlaps with the edge E of the protective layer 18a when viewed in the downward direction, and extends along the edge E of the protective layer 18a when viewed in the downward direction. Thus, a protrusion P1 is formed that overlaps with the internal conductor 28a when viewed in the downward direction. Furthermore, the protective layer 18a is formed on the upper main surface of the laminate 12 having such a protrusion P1. As a result, the thickness T1 of the protective layer 18a at the portion where it overlaps with the protrusion P1 when viewed in the downward direction becomes smaller than the thickness T2 of the protective layer 18a at the portion where it does not overlap with the protrusion P1 when viewed in the downward direction. In the multilayer substrate 10 described above, the thickness of the protective layer 18a in the vertical direction at the edge E is small. Therefore, the undercut of the protective layer 18a is reduced. Therefore, according to the multilayer substrate 10, peeling of the protective layer 18a can be suppressed.

[0123] According to the multilayer substrate 10, the peeling of the protective layer 18a can be suppressed without adding new processes. More specifically, in the multilayer substrate 10, an internal conductor 28a is formed to form the protrusion P1. At least a portion of one or more circuit conductors and the internal conductor 28a are metal foils provided on the main surfaces of the insulating layers 16a to 16d. That is, the process of forming the internal conductor 28a can be performed in the same way as the process of forming at least a portion of one or more circuit conductors. Therefore, it is not necessary to add a new process for forming the internal conductor 28a.

[0124] Because the second interval A2 is curved, the protective layer 18a is prone to peeling within the second interval A2. Therefore, the protrusion P1 is located in the second interval A2. Thus, the peeling of the protective layer 18a is effectively suppressed.

[0125] Based on the multilayer substrate 10, the protrusion P1 is easily formed. More specifically, viewed from the downward direction, the mounting electrode 26a is located in the region surrounded by the annular edge E of the opening h1. Moreover, viewed from the downward direction, the internal conductor 28a has an annular shape along the annular edge E of the opening h1. Thus, during the crimping process of the laminate 12, the rigid mounting electrode 26a is pushed downward, and the mounting electrode 26a and its surroundings are recessed downward. On the other hand, the portion of the upper main surface of the laminate 12 containing the internal conductor 28a is pushed upward by the internal conductor 28a. As a result, the protrusion P1 is easily formed.

[0126] (First variation)

[0127] Hereinafter, the multilayer substrate 10a involved in the first modified example will be described with reference to the accompanying drawings. Figure 6 These are cross-sectional views and top views of the multilayer substrate 10a.

[0128] The difference between the multilayer substrate 10a and the multilayer substrate 10 is that it also has an internal conductor 34a and a plurality of first connecting conductors v10.

[0129] The multilayer substrate 10a also includes internal conductors 34a. Therefore, there are multiple internal conductors. Furthermore, viewed downwards (in the negative Z-axis direction), the internal conductors 28a and 34a overlap each other. Viewed downwards, the internal conductor 34a has the same shape as the internal conductor 28a. The internal conductor 34a is located on the upper main surface of the insulating layer 16c. The multilayer substrate 10a also includes multiple first connecting conductors v10. These multiple first connecting conductors v10 penetrate the insulating layer 16b (any one of the multiple insulating layers 16a to 16d) along the vertical axis (Z-axis) and connect the internal conductors 28a and 34a (two of the multiple internal conductors). Viewed downwards, the multiple first connecting conductors v10 are arranged at equal intervals along the internal conductors 28a and 34a. 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 can achieve the same effects as the multilayer substrate 10.

[0130] According to the multilayer substrate 10a, the inner conductor 34a and a plurality of first connecting conductors v10 are located below the inner conductor 28a. As a result, it becomes easier to form the protrusion P1.

[0131] (Second variation)

[0132] The multilayer substrate 10b of the second modified example will be described below with reference to the accompanying drawings. Figure 7 This is a cross-sectional view of the multilayer substrate 10b.

[0133] The multilayer substrate 10b differs from the multilayer substrate 10 in the following aspects: The edge E of the protective layer 18a is a straight line extending along the front-rear axis. The multilayer substrate 10b also includes internal conductors 34a, 36a, 38a, a surface conductor 40a, a first connecting conductor v10, a second connecting conductor v12, a third connecting conductor v14, and a fourth connecting conductor v16.

[0134] The internal conductors 34a, 36a, and 38a are located on the upper main surfaces of the insulating layers 16c to 16e, respectively. Viewed downwards, the internal conductors 34a, 36a, and 38a overlap with the edge E of the protective layer 18a. Therefore, viewed downwards, the internal conductors 34a, 36a, and 38a extend along the front-to-back axis. Viewed downwards, the internal conductors 34a, 36a, and 38a overlap each other.

[0135] The surface conductor 40a is located on the upper main surface (positive main surface) of the laminate 12, and when viewed in the downward direction (negative direction of the Z-axis), it overlaps with the edge E of the protective layer 18a. Therefore, when viewed in the downward direction, the surface conductor 40a extends along the front-to-back axis. When viewed in the downward direction, the surface conductor 40a overlaps with the inner conductors 34a, 36a, and 38a.

[0136] Multiple first connecting conductors v10 penetrate the insulating layer 16b (any one of the multiple insulating layers 16a to 16d) along the vertical axis (Z-axis) and connect the inner conductors 28a and 34a (two of the multiple inner conductors). Viewed downwards, the multiple first connecting conductors v10 are arranged along the inner conductors 28a, 34a, 36a, 38a and the surface conductor 40a.

[0137] Multiple second connecting conductors v12 penetrate the insulating layer 16c (any one of the multiple insulating layers 16a to 16d) along the vertical axis (Z-axis) and connect the inner conductors 34a and 36a (two of the multiple inner conductors). The multiple second connecting conductors v12 are located below the multiple first connecting conductors v10 (on the negative side of the Z-axis) and overlap with the multiple first connecting conductors v10 when viewed downwards (in the negative direction of the Z-axis). When viewed downwards, the multiple second connecting conductors v12 are arranged along the inner conductors 28a, 34a, 36a, 38a and the surface conductor 40a.

[0138] Multiple third connecting conductors v14 penetrate the insulating layer 16d (any one of the multiple insulating layers 16a to 16d) along the vertical axis (Z-axis) and connect the inner conductors 36a and 38a (two of the multiple inner conductors). The multiple third connecting conductors v14 are located below the multiple first connecting conductors v10 (on the negative side of the Z-axis) and overlap with the multiple first connecting conductors v10 when viewed downwards (in the negative direction of the Z-axis). When viewed downwards, the multiple third connecting conductors v14 are arranged along the inner conductors 28a, 34a, 36a, 38a and the surface conductor 40a.

[0139] Multiple fourth connecting conductors v16 penetrate the insulating layer 16a (any one of the multiple insulating layers 16a to 16d) along the vertical axis (Z-axis) and connect the surface conductor 40a and the inner conductor 28a. Viewed downwards (the negative direction of the Z-axis), the multiple fourth connecting conductors v16 overlap with the multiple first connecting conductors v10. Viewed downwards, the multiple fourth connecting conductors v16 are arranged along the inner conductors 28a, 34a, 36a, 38a and the surface conductor 40a. The other structures of the multilayer substrate 10b are the same as those of the multilayer substrate 10, and therefore descriptions are omitted. The multilayer substrate 10b achieves the same effects as the multilayer substrate 10.

[0140] According to the multilayer substrate 10b, in addition to the internal conductor 28a, there are also internal conductors 34a, 36a, 38a, a surface conductor 40a, a plurality of first connecting conductors v10, a plurality of second connecting conductors v12, a plurality of third connecting conductors v14, and a plurality of fourth connecting conductors v16. As a result, it becomes easier to form the protrusion P1.

[0141] (3rd variation)

[0142] The multilayer substrate 10c of the third modified example will be described below with reference to the accompanying drawings. Figure 8 This is a cross-sectional view of the multilayer substrate 10c.

[0143] The multilayer substrate 10c differs from the multilayer substrate 10 in that an undercut is formed at the edge E of the opening h1 of the protective layer 18a. However, when viewed from the downward direction, the thickness T1 of the protective layer 18a overlapping the protrusion P1 is less than the thickness T2 of the protective layer 18a not overlapping the protrusion P1 when viewed from the downward direction. Therefore, in the multilayer substrate 10b, the undercut at the edge E of the opening h1 of the protective layer 18a is smaller. The other structures of the multilayer substrate 10c are the same as those of the multilayer substrate 10, and therefore descriptions are omitted. The multilayer substrate 10c can achieve the same effect as the multilayer substrate 10.

[0144] (4th variation)

[0145] The multilayer substrate 10d involved in the fourth modified example will be described below with reference to the accompanying drawings. Figure 9 These are cross-sectional views and top views of the multilayer substrate 10d.

[0146] The multilayer substrate 10d differs from multilayer substrate 10b in that it has multiple internal conductors 28a instead of internal conductors 28a, and it lacks internal conductors 34a, 36a, 38a, surface conductor 40a, first connecting conductor v10, second connecting conductor v12, third connecting conductor v14, and fourth connecting conductor v16. The multiple internal conductors 28a are disposed inside the laminate 12. Viewed in the downward direction (negative Z-axis direction), the multiple internal conductors 28a overlap with the edge E of the protective layer 18b, and when viewed in the downward direction (negative Z-axis direction), the multiple internal conductors 28a are arranged at equal intervals along the edge E of the protective layer 18a. The multiple internal conductors 28a do not contact each other when adjacent conductors are in contact. The other structures of multilayer substrate 10d are the same as those of multilayer substrate 10b, and therefore descriptions are omitted. Multilayer substrate 10d can achieve the same effect as multilayer substrate 10. Therefore, at the edge E where it overlaps with the multiple internal conductors 28a, the protective layer 18a becomes less prone to peeling.

[0147] (5th variation)

[0148] The multilayer substrate 10e of the fifth modified example will be described below with reference to the accompanying drawings. Figure 10 These are cross-sectional views and top views of the multilayer substrate 10e.

[0149] The difference between multilayer substrate 10e and multilayer substrate 10d is that multilayer substrate 10e has multiple first connecting conductors v10 instead of multiple internal conductors 28a. The multiple first connecting conductors v10 are multiple internal conductors. The multiple first connecting conductors v10 extend through the insulating layer 16b along the vertical axis. Viewed in the downward direction (negative Z-axis direction), the multiple first connecting conductors v10 overlap with the edge E of the protective layer 18b, and viewed in the downward direction (negative Z-axis direction), the multiple first connecting conductors v10 are arranged at equal intervals along the edge E of the protective layer 18a. The multiple first connecting conductors v10 do not contact each other when adjacent conductors are in contact. The other structures of multilayer substrate 10e are the same as those of multilayer substrate 10d, and therefore descriptions are omitted. Multilayer substrate 10e can achieve the same effects as multilayer substrate 10d.

[0150] (Sixth variation)

[0151] The multilayer substrate 10f involved in the sixth modified example will be described below with reference to the accompanying drawings. Figure 11 This is a cross-sectional view of the multilayer substrate 10f. Figure 12 This is a rear view of the multilayer substrate 10f in use.

[0152] The difference between multilayer substrate 10f and multilayer substrate 10d is that the laminate 12 is cut at the protrusion P1, and, when viewed from below, the internal conductor 28a has a line shape. For example... Figure 12 As shown, this multilayer substrate 10f is bendable. Specifically, the multilayer substrate 10f has a first section A1 and a second section A2. A protrusion P1 is located in the second section A2. Viewed in the forward direction (the positive direction of the Y-axis orthogonal to the Z-axis), the second section A2 is bendable. The other structures of the multilayer substrate 10f are the same as those of the multilayer substrate 10d, so descriptions are omitted.

[0153] Next, the manufacturing method of the multilayer substrate 10f will be described with reference to the accompanying drawings. Figure 13 , Figure 14 as well as Figure 15 This is a cross-sectional view of the multilayer substrate 10f during manufacturing. Figure 16 This is a top view of the mother substrate 100.

[0154] First, prepare insulating layers 16a to 16e with metal foil attached to the upper or lower main surface. Then, by patterning the metal foil, form signal conductor layer 20, first ground conductor layer 22, second ground conductor layer 24, mounting electrodes 26a and 26b, and internal conductor 28a.

[0155] Next, as Figure 13 As shown, insulating layers 16a to 16e are arranged sequentially from top to bottom. Then, the laminate containing the insulating layers 16a to 16e is pressed together (pressing process). In the pressing process, isotropic pressing is used. Furthermore, in the hot pressing process, heat treatment is also performed. At this time, as... Figure 14 As shown, the insulating layer 16a is pushed upward by the internal conductor 28a. As a result, during the crimping process, protrusions P1 are formed on the upper main surface (positive main surface) of the laminate 12 in the portions overlapping with the internal conductor 28a. Furthermore, the internal conductor 28a is disposed inside the laminate 12.

[0156] Next, as Figure 15 As shown, protective layers 18a and 18b are formed on the laminated body 12 after pressing (protective layer formation process). In the protective layer formation process, protective layer 18a is formed on the upper main surface (positive main surface) of the laminated body 12, such that when viewed in the downward direction (negative direction of the Z-axis), protective layer 18a covers protrusion P1. Specifically, the material of protective layers 18a and 18b is applied to the upper and lower main surfaces of the laminated body 12 by screen printing. When viewed in the downward direction (negative direction of the Z-axis), the thickness T1 of the protective layer 18a overlapping with protrusion P1 is less than the thickness T2 of the protective layer 18a not overlapping with protrusion P1 when viewed in the downward direction (negative direction of the Z-axis).

[0157] Next, as Figure 11 As shown, the laminate 12 with protective layers 18a and 18b is cut (cutting process). In the cutting process, the laminate 12 is cut so that, when viewed in the downward direction (negative direction of the Z-axis), the protrusion P1 is segmented. In the cutting process, as... Figure 16 As shown, the mother substrate 100 is cut along the inner conductor 28a. After the above process, the multilayer substrate 10f is completed.

[0158] (Other implementation methods)

[0159] The multilayer substrates involved in this utility model are not limited to multilayer substrates 10, 10a to 10f, and can be modified within the scope of their intent. In addition, the structures of multilayer substrates 10, 10a to 10f can be arbitrarily combined.

[0160] In addition, the protective layer 18b is not a necessary component.

[0161] Alternatively, a protrusion can be provided on the lower main surface of the laminate 12, and the edge of the protective layer 18b overlaps with the protrusion.

[0162] In addition, the signal conductor layer 20, the first ground conductor layer 22, and the second ground conductor layer 24 are not essential components.

[0163] Alternatively, the material of the insulating layers 16a to 16e can also be ceramic, for example.

[0164] The protective layer 18a only needs to cover at least a portion of the upper main surface of the laminate 12. Therefore, the protective layer 18a can also cover the entire upper main surface of the laminate 12. In this case, a protrusion P1 is present near the outer edge of the upper main surface of the laminate 12. This can prevent the protective layer 18a from peeling off from the outer edge of the upper main surface of the laminate 12.

[0165] Furthermore, the potentials of the internal conductors 28a, 34a, 36a, 38a and the surface conductor 40a do not have to be floating potentials. For example, the internal conductors 28a, 34a, 36a, 38a and the surface conductor 40a can also be connected to ground potential. However, when the potentials of the internal conductors 28a, 34a, 36a, 38a and the surface conductor 40a are floating potentials, they become less likely to affect surrounding electrical circuits.

[0166] Alternatively, in the multilayer substrate 10e, only one first connecting conductor v10 may be provided.

[0167] In addition, in the multilayer substrates 10a and 10e, the plurality of first connecting conductors v10 may also be in contact with each other in adjacent conductors.

[0168] This utility model has the following structure. (1)

[0170] A multilayer substrate comprising a laminate, a protective layer, and one or more internal conductors.

[0171] The laminate has a structure in which multiple insulating layers are stacked along the Z-axis.

[0172] The laminate has a positive principal plane and a negative principal plane located on the negative side of the Z-axis, which is closer to the positive principal plane.

[0173] The protective layer covers at least a portion of the main surface.

[0174] The material of the protective layer is different from the material of the plurality of insulating layers.

[0175] One or more internal conductors are disposed inside the laminate and, when viewed in the negative Z-axis direction, overlap with the edge of the protective layer and extend along the edge of the protective layer when viewed in the negative Z-axis direction.

[0176] A protrusion is provided on the main surface of the laminate.

[0177] Viewed in the negative direction of the Z-axis, the protrusion overlaps with the edge of the protective layer and the one or more inner conductors, and has a linear shape extending along the edge of the protective layer.

[0178] When viewed in the negative Z-axis direction, the thickness of the protective layer at the portion where it overlaps with the protrusion is less than the thickness of the protective layer at the portion where it does not overlap with the protrusion when viewed in the negative Z-axis direction.

[0179] When viewed in the negative direction of the Z-axis, the length of the linear protrusion is longer than the width of the linear protrusion. (2)

[0181] In the multilayer substrate described in (1),

[0182] The multilayer substrate also includes one or more circuit conductors that form an electrical circuit.

[0183] The one or more internal conductors are not electrically connected in series with the one or more circuit conductors. (3)

[0185] In the multilayer substrates described in (1) or (2),

[0186] The multilayer substrate also includes one or more circuit conductors that form an electrical circuit.

[0187] At least a portion of the more than one circuit conductor and the more than one internal conductor are metal foils disposed on the main surface of the plurality of insulating layers. (4)

[0189] In any of the multilayer substrates described in (1) to (3),

[0190] The number of the one or more internal conductors is multiple.

[0191] When viewed in the negative direction of the Z-axis, the plurality of internal conductors overlap each other. (5)

[0193] In the multilayer substrate described in (4),

[0194] The multilayer substrate also includes a first connecting conductor.

[0195] The first connecting conductor passes through any one of the plurality of insulating layers along the Z-axis and connects two of the plurality of inner conductors. (6)

[0197] In the multilayer substrate described in (5),

[0198] The multilayer base also includes a second connecting conductor.

[0199] The second connecting conductor passes through any one of the plurality of insulating layers along the Z-axis and connects two of the plurality of inner conductors. It is located on the negative side of the Z-axis than the first connecting conductor and overlaps with the first connecting conductor when viewed in the negative direction of the Z-axis. (7)

[0201] In the multilayer substrates described in (1) or (2),

[0202] The one or more internal conductors are connecting conductors that pass through any one of the plurality of insulating layers along the Z-axis. (8)

[0204] In any of the multilayer substrates described in (1) to (7),

[0205] The multilayer substrate has a first section and a second section.

[0206] The protrusion is located in the second interval.

[0207] When viewed in the positive direction of the Y-axis, which is orthogonal to the Z-axis, the second interval is curved. (9)

[0209] In any of the multilayer substrates described in (1) to (8),

[0210] The multilayer substrate also has a surface conductor.

[0211] The surface conductor is located on the positive main plane and overlaps with the edge of the protective layer when viewed in the negative direction of the Z-axis. (10)

[0213] In any of the multilayer substrates described in (1) to (9),

[0214] The multilayer substrate also includes mounting electrodes.

[0215] Viewed in the negative direction of the Z-axis, the protective layer has a ring-shaped edge.

[0216] The mounting electrode is located on the positive main plane, and when viewed in the negative direction of the Z-axis, it is situated in the region surrounded by the edge of the ring shape.

[0217] Viewed in the negative direction of the Z-axis, the inner conductor has a ring shape along the edge of the ring shape.

[0218] Viewed in the negative direction of the Z-axis, the protrusion has a ring shape along the edge of the ring shape. (11)

[0220] A multilayer substrate comprising a laminate, a protective layer, and multiple internal conductors.

[0221] The laminate has a structure in which multiple insulating layers are stacked along the Z-axis.

[0222] The laminate has a positive principal plane and a negative principal plane located on the negative side of the Z-axis, which is closer to the positive principal plane.

[0223] The protective layer covers a portion of the main surface.

[0224] The material of the protective layer is different from the material of the plurality of insulating layers.

[0225] The plurality of internal conductors are disposed inside the laminate and, when viewed in the negative Z-axis direction, overlap with the edge of the protective layer and are arranged along the edge of the protective layer when viewed in the negative Z-axis direction.

[0226] A protrusion is provided on the main surface of the laminate.

[0227] Viewed in the negative direction of the Z-axis, the protrusion overlaps with the edge of the protective layer and the plurality of internal conductors, and has a linear shape extending along the edge of the protective layer.

[0228] When viewed in the negative direction of the Z-axis, the thickness of the protective layer at the portion where it overlaps with the protrusion is less than the thickness of the protective layer at the portion where it does not overlap with the protrusion when viewed in the negative direction of the Z-axis. (12)

[0230] A method for manufacturing a multilayer substrate, comprising:

[0231] The pressing process, pressing laminates; and

[0232] The protective layer forming process involves forming a protective layer on the laminated body after pressing.

[0233] The laminate has a structure in which multiple insulating layers are stacked along the Z-axis.

[0234] The laminate has a positive principal plane and a negative principal plane located on the negative side of the Z-axis, which is closer to the positive principal plane.

[0235] The protective layer covers at least a portion of the main surface.

[0236] The material of the protective layer is different from the material of the plurality of insulating layers.

[0237] One or more internal conductors are disposed inside the laminate.

[0238] During the crimping process, a protrusion is formed on the main surface of the laminate, in the portion overlapping with one or more internal conductors.

[0239] In the protective layer forming process, the protective layer is formed on the positive main surface such that when viewed in the negative direction of the Z-axis, the edge of the protective layer overlaps with the protrusion. (13)

[0241] In the manufacturing method of the multilayer substrate described in (12),

[0242] Viewed in the negative direction of the Z-axis, the protective layer has a ring-shaped edge.

[0243] The mounting electrode is located on the positive principal plane, and when viewed in the negative direction of the Z-axis, it is situated in the region surrounded by the edge of the ring shape.

[0244] Viewed in the negative direction of the Z-axis, the protrusion has a ring shape along the edge of the ring shape.

[0245] Viewed in the negative direction of the Z-axis, the inner conductor has a ring shape along the edge of the ring shape. (14)

[0247] A method for manufacturing a multilayer substrate, comprising:

[0248] The pressing process involves pressing laminated bodies.

[0249] The protective layer forming process involves forming a protective layer on the laminated body after pressing; and

[0250] The cutting process involves cutting the laminated body with the protective layer formed thereon.

[0251] The laminate has a structure in which multiple insulating layers are stacked along the Z-axis.

[0252] The laminate has a positive principal plane and a negative principal plane located on the negative side of the Z-axis, which is closer to the positive principal plane.

[0253] The protective layer covers at least a portion of the main surface.

[0254] The material of the protective layer is different from the material of the plurality of insulating layers.

[0255] One or more internal conductors are disposed inside the laminate.

[0256] During the crimping process, a protrusion is formed on the main surface of the laminate, in the portion overlapping with one or more internal conductors.

[0257] In the protective layer forming process, the protective layer is formed on the positive main surface such that, when viewed in the negative direction of the Z-axis, the protective layer covers the protrusion.

[0258] In the cutting process, the laminate is cut such that when viewed in the negative direction of the Z-axis, the protrusion is segmented.

Claims

1. A multilayer substrate characterized by comprising a laminate, a protective layer, and one or more internal conductors, the laminate has a configuration in which a plurality of insulator layers are stacked along a Z axis, the laminate has a positive main face and a negative main face located at a position on a negative side of the Z axis from the positive main face, the protective layer covers at least a portion of the positive main face, a material of the protective layer is different from a material of the plurality of insulator layers, the one or more internal conductors are provided inside the laminate and, as viewed in a negative direction of the Z axis, overlap with a rim of the protective layer and, as viewed in the negative direction of the Z axis, extend along the rim of the protective layer, a protrusion is provided on the positive main face of the laminate, the protrusion, as viewed in the negative direction of the Z axis, overlaps with the rim of the protective layer and the one or more internal conductors and has a linear shape that extends along the rim of the protective layer, a thickness of the protective layer at a portion where the protective layer overlaps with the protrusion, as viewed in the negative direction of the Z axis, is smaller than a thickness of the protective layer at a portion where the protective layer does not overlap with the protrusion, as viewed in the negative direction of the Z axis, a length of the linear-shaped protrusion, as viewed in the negative direction of the Z axis, is longer than a width of the linear-shaped protrusion.

2. The multilayer substrate according to claim 1, characterized in that the multilayer substrate comprises one or more circuit conductors that form an electrical circuit, the one or more internal conductors are not electrically connected in series with the one or more circuit conductors.

3. The multilayer substrate according to claim 1, characterized in that the multilayer substrate comprises one or more circuit conductors that form an electrical circuit, at least a portion of the one or more circuit conductors and the one or more internal conductors are metal foils provided on main faces of the plurality of insulator layers.

4. The multilayer substrate according to claim 2, characterized in that at least a portion of the one or more circuit conductors and the one or more internal conductors are metal foils provided on main faces of the plurality of insulator layers.

5. The multilayer substrate according to any one of claims 1 to 4, characterized in that the number of the one or more internal conductors is plural, the plural internal conductors overlap with each other, as viewed in the negative direction of the Z axis.

6. The multilayer substrate according to claim 4, characterized in that the multilayer substrate comprises a first connection conductor, the first connection conductor penetrates any one of the plurality of insulator layers along the Z axis and connects two of the plural internal conductors.

7. The multilayer substrate according to claim 6, characterized in that the multilayer substrate comprises a second connection conductor, the second connection conductor penetrates any one of the plurality of insulator layers along the Z axis and connects two of the plural internal conductors, is located at a position on a negative side of the Z axis from the first connection conductor, and overlaps with the first connection conductor, as viewed in the negative direction of the Z axis.

8. The multilayer substrate according to any one of claims 1 to 4, characterized in that ​ The one or more internal conductors are connection conductors that pass through any of the plurality of insulator layers along the Z-axis.

9. The multilayer substrate according to any one of claims 1 to 4, wherein the multilayer substrate has a first region and a second region, the protrusion is located in the second region, the second region is curved when viewed in the positive direction of a Y-axis orthogonal to the Z-axis.

10. The multilayer substrate according to any one of claims 1 to 4, wherein the multilayer substrate has a surface conductor, the surface conductor is located in the positive main surface and overlaps with the edge of the protective layer when viewed in the negative direction of the Z-axis.

11. The multilayer substrate according to any one of claims 1 to 4, wherein the multilayer substrate has a mounting electrode, the protective layer has an annular edge when viewed in the negative direction of the Z-axis, the mounting electrode is located in the positive main surface and in a region surrounded by the annular edge when viewed in the negative direction of the Z-axis, the internal conductor has an annular shape along the annular edge when viewed in the negative direction of the Z-axis, the protrusion has an annular shape along the annular edge when viewed in the negative direction of the Z-axis.

12. A multilayer substrate, comprising: a laminate, a protective layer, and a plurality of internal conductors, the laminate has a configuration in which a plurality of insulator layers are stacked along a Z-axis, the laminate has a positive main surface and a negative main surface located on a negative side of the Z-axis from the positive main surface, the protective layer covers a portion of the positive main surface, a material of the protective layer is different from a material of the plurality of insulator layers, the plurality of internal conductors are disposed inside the laminate and overlap with an edge of the protective layer when viewed in the negative direction of the Z-axis and are arranged along the edge of the protective layer when viewed in the negative direction of the Z-axis, a protrusion is provided on the positive main surface of the laminate, the protrusion overlaps with the edge of the protective layer and the plurality of internal conductors when viewed in the negative direction of the Z-axis and has a linear shape extending along the edge of the protective layer, a thickness of the protective layer in a portion where the protective layer overlaps with the protrusion when viewed in the negative direction of the Z-axis is smaller than a thickness of the protective layer in a portion where the protective layer does not overlap with the protrusion when viewed in the negative direction of the Z-axis.

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