JP6065119B2 - Multilayer board - Google Patents

Description

  The present invention generally relates to a multilayer substrate, and more particularly to a multilayer substrate in which a deformable flexible portion is provided in a laminate having a plurality of laminated resin layers.

  Regarding a conventional multilayer substrate, for example, Japanese Patent Application Laid-Open No. 2006-41044 ensures good bendability even for high-density wiring, reduces fatigue of the conductor layer during bending, and prevents disconnection. A multilayer flexible printed circuit board has been disclosed for the purpose of realizing a high degree of bending resistance (Patent Document 1). In the multilayer flexible printed circuit board disclosed in Patent Document 1, an air gap is provided between layers where two flexible printed circuit boards are stacked. A reinforcing layer is formed on the surface of the flexible printed circuit board to receive stress concentrated on the end of the air gap during bending.

JP 200641044 A

  As disclosed in the above-mentioned patent document, a multilayer board provided with a flexible portion (flexible) is used in an electric device such as a foldable mobile phone. In such a multilayer substrate, stress tends to concentrate on a specific part of the flexible part with deformation, so that the durability of the flexible part is impaired. On the other hand, as a means for improving the durability of the flexible part, it is conceivable to add reinforcement to the flexible part. However, depending on the reinforcing method, there is a concern that the flexibility of the flexible portion is greatly impaired.

  Accordingly, an object of the present invention is to solve the above-described problems, and to provide a multilayer substrate having improved durability while ensuring the flexibility of the flexible portion.

  A multilayer substrate according to the present invention includes a laminate having a plurality of laminated resin layers made of a flexible resin. The laminated body is provided with a deformable flexible portion that extends in a band shape while repeatedly changing the traveling direction when viewed from the laminating direction of the resin layer. The flexible portion includes a folded portion at a position where the traveling direction is changed. The laminate further includes a metallic reinforcing layer that is partially provided on the surface of the folded portion when viewed from the laminating direction of the resin layer and is not connected to any other electric circuit in the laminate.

  According to the multilayer substrate configured as described above, the durability of the flexible portion can be improved by providing the metal reinforcing layer in the folded portion where the stress tends to concentrate with the deformation of the flexible portion. . At this time, since the reinforcing layer is partially provided on the surface of the folded portion when viewed from the direction in which the resin layers are laminated, the flexibility of the flexible portion can be suppressed from being impaired.

  Preferably, the reinforcing layer is interposed between the plurality of resin layers. According to the multilayer substrate configured as described above, the durability of the flexible portion can be improved by the internal structure of the laminate.

  Preferably, the reinforcing portion is provided in a net shape. According to the multilayer substrate configured as described above, the durability of the flexible portion can be improved regardless of the direction of the stress acting on the folded portion when the flexible portion is deformed.

  Preferably, the flexible portion extends in a band shape while repeatedly reversing the traveling direction by 180 ° so as to form a meander shape as a whole.

  According to the multilayer substrate configured as described above, it is possible to improve the durability while ensuring the flexibility of the flexible portion having a meander shape as a whole.

  Preferably, the flexible portion extends in a band shape while repeatedly changing the traveling direction by 90 ° so as to form a spiral shape as a whole.

  According to the multilayer substrate configured as described above, it is possible to improve the durability while ensuring the flexibility of the flexible portion having a spiral shape as a whole.

  Preferably, the reinforcing layer is provided along the inner peripheral edge of the flexible portion that changes the traveling direction in the folded portion.

  According to the multilayer substrate configured as described above, by providing the reinforcing layer on the inner peripheral edge where stress is more likely to be concentrated in the folded portion, the flexibility of the flexible portion is sufficiently ensured and the durability thereof is increased. It can be improved efficiently.

  More preferably, the reinforcing layer is further provided along the outer peripheral edge of the flexible portion that changes the traveling direction in the folded portion.

  According to the multilayer substrate configured as described above, the durability of the flexible portion can be further improved.

Preferably, the laminate further includes a wiring layer provided in the same layer as the reinforcing layer.
According to the multilayer substrate configured as described above, the reinforcing layer can be formed by the same process as the wiring layer.

  As described above, according to the present invention, it is possible to provide a multilayer substrate with improved durability while ensuring the flexibility of the flexible portion.

It is sectional drawing which shows the multilayer substrate in Embodiment 1 of this invention. It is sectional drawing which shows the multilayer substrate along the II-II line | wire in FIG. It is sectional drawing which shows the 1st modification of the multilayer substrate in FIG. It is sectional drawing which shows the 2nd modification of the multilayer substrate in FIG. It is sectional drawing which shows the multilayer substrate in Embodiment 2 of this invention. It is sectional drawing which shows the multilayer substrate along the VI-VI line in FIG. It is sectional drawing which shows the 1st modification of the multilayer substrate in FIG. It is sectional drawing which shows the 2nd modification of the multilayer substrate in FIG. It is a top view which shows the multilayer substrate in Embodiment 3 of this invention.

  Embodiments of the present invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are denoted by the same reference numerals.

(Embodiment 1)
1 is a cross-sectional view showing a multilayer substrate according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view showing the multilayer substrate along the line II-II in FIG. FIG. 1 shows a cross section of the multilayer substrate along the line II in FIG.

  With reference to FIG. 1 and FIG. 2, first, the overall structure of the multilayer substrate 10 in the present embodiment will be described. The multilayer substrate 10 includes a plurality of resin layers 21A, 21B, 21C, 21D, 21E, 21F (hereinafter, If not particularly distinguished, it is referred to as a resin layer 21), a plurality of wiring layers 26G, 26H, 26I, 26J, 26K (hereinafter referred to as a wiring layer 26 unless otherwise distinguished) and an inner via 27. A laminate 12 is provided.

  The resin layer 21 is formed from a thermoplastic resin. The resin layer 21 is made of, for example, polyimide, LCP (liquid crystal polymer), PEEK (polyether ether ketone), or PPS (polyphenylene sulfide). The plurality of resin layers 21 are stacked in the direction indicated by the arrow 101 in FIG. 1 (hereinafter, the direction indicated by the arrow 101 is referred to as the stacking direction of the resin layers 21). The resin layer 21A, the resin layer 21B, the resin layer 21C, the resin layer 21D, the resin layer 21E, and the resin layer 21F are arranged from top to bottom in the order listed. The plurality of laminated resin layers 21 form the appearance of the laminate 12.

  The wiring layer 26 is a metal film formed of a metal such as copper, silver, aluminum, stainless steel, nickel, or gold, or an alloy containing these metals. Specifically, the wiring layer 26 is, for example, a metal foil such as a copper foil. The wiring layer 26 is provided inside the stacked body 12. The wiring layer 26 is disposed between the plurality of resin layers 21. More specifically, the wiring layer 26G is disposed between the resin layer 21A and the resin layer 21B, the wiring layer 26H is disposed between the resin layer 21B and the resin layer 21C, and the wiring layer 26I is formed of the resin layer 21C. The wiring layer 26J is disposed between the resin layer 21D and the resin layer 21E, and the wiring layer 26K is disposed between the resin layer 21E and the resin layer 21F.

  The wiring layer 26 is formed in a predetermined pattern shape, and forms various electric circuits such as a strip line, a microstrip line, a coil, and a capacitor.

  The inner via 27 is made of a conductive material. The inner via 27 is provided inside the stacked body 12. The inner vias 27 extend in the direction in which the resin layers 21 are laminated, and connect the wiring layers 26 provided in different layers to each other.

  In addition, in the figure, the case where the laminated body 12 has a rectangular planar view when viewed from the laminating direction of the resin layer 21 is shown, but the laminated body 12 has a planar view of an arbitrary shape other than the rectangular shape. You may have. Further, in the figure, only the wiring layer 26 provided inside the stacked body 12 is shown, but the wiring layer 26 may also be provided on the surface of the stacked body 12.

  The laminate 12 is provided with a main body part 110, a flexible part 120, and a pad part 130. In the present embodiment, the flexible portion 120 and the pad portion 130 are arranged in the order given on both sides of the main body portion 110 as a center.

  The main body 110 is a rigid portion that is less likely to deform than the flexible portion 120. Various electric components may be mounted on the surface of the main body 110. The flexible part 120 is a deformable flexible part. The flexible part 120 extends from the peripheral edge of the main body part 110 when the laminate 12 is viewed in plan. The pad part 130 is provided at the tip of the flexible part 120 extending from the main body part 110. The pad portion 130 may be provided with a connector for electrical connection for connecting the wiring provided in the laminate 12 and an external circuit.

  In the present embodiment, the flexible portion 120 has a direction in which the resin layer 21 is laminated (a direction indicated by an arrow 101 in FIG. 1) and a direction connecting the main body portion 110 and the pad portion 130 (indicated by an arrow 102 in FIG. 2). Direction and expansion / contraction direction). Due to the flexibility of the flexible part 120, a part where a difference in height occurs between the main body part 110 and the pad part 130, or a distance between the main body part 110 and the pad part 130 changes. The multilayer substrate 10 can be mounted on the part. In addition, the multilayer substrate 10 can be mounted on a portion where variations in height and variations in mounting length occur.

  In order to increase the flexibility of the flexible part 120, the number of resin layers 21 in the flexible part 120 may be smaller than the number of resin layers 21 in the main body part 110.

  The laminated body 12 is formed with a plurality of slits 31p, 31q, 31r for providing the deformable flexible portion 120 (hereinafter referred to as slits 31 unless otherwise distinguished).

  The flexible portion 120 extends in a band shape while repeatedly changing the traveling direction as seen from the direction in which the resin layers 21 are laminated. In this embodiment, the flexible portion 120 has a wave shape as a whole. The flexible part 120 has, as its constituent parts, a folded part 37 disposed at a position where the traveling direction is changed, and an intermediate part 36 that connects between adjacent folded parts 37.

  The folded portion 37 and the intermediate portion 36 are alternately provided between the main body portion 110 and the pad portion 130. In the present embodiment, the flexible portion 120 is composed of three folded portions 37 and two intermediate portions 36, and the folded portions 37 disposed at both ends thereof are connected to the main body portion 110 and the pad portion 130, respectively. Has been.

  When a center line extending along the traveling direction is drawn on the flexible part 120 in FIG. 2, the center line has a wave shape in which a belly is disposed on the folded part 37.

  In particular, in the present embodiment, the flexible portion 120 has a meander shape as a whole by extending in a strip shape while repeatedly reversing the traveling direction by 180 ° when viewed from the laminating direction of the resin layer 21. A center line extending along the traveling direction of the flexible portion 120 has a rectangular wave shape.

  The slits 31 formed in the laminated body 12 penetrate in the laminating direction of the resin layer 21. When viewed from the stacking direction of the resin layer 21, the slit 31 extends toward the folded portion 37 along the traveling direction of the intermediate portion 36. The slit 31 extends linearly. The plurality of slits 31 extend in parallel to each other. The plurality of slits 31 are formed at intervals in the direction connecting the main body 110 and the pad portion 130.

  The slit 31p, the slit 31q, and the slit 31r are arranged from the main body 110 side to the pad portion 130 side in the order given. The stacked body 12 has an end side 12a and an end side 12b arranged to face the end side 12a. The slit 31p extends linearly from the end side 12b to the front of the end side 12a. The slit 31q extends linearly from the end side 12a to the front of the end side 12b. The slit 31r extends linearly from the end side 12b to the front of the end side 12a.

  A folded portion 37 is provided at the tip of the slits 31p, 31q, 31r extending linearly. An intermediate portion 36 is provided between the slit 31p and the slit 31q and between the slit 31q and the slit 31r.

  The flexible portion 120 is formed by alternately forming slits 31 extending from the end side 12a to the front side of the end side 12b and slits 31 extending from the end side 12b to the front side of the end side 12a. It is formed into a shape.

  In the multilayer substrate 10 in the present embodiment, the laminate 12 further has a metal reinforcing layer 28.

  The reinforcing layer 28 is provided on the folded portion 37. The reinforcing layer 28 is partially provided on the surface of the folded portion 37 when viewed from the lamination direction of the resin layer 21. In the present embodiment, the reinforcing layer 28 is provided in a net shape on the surface of the folded portion 37 when viewed from the lamination direction of the resin layer 21.

  In FIG. 2, a reinforcing layer 28 having a rectangular lattice structure is shown as one form in the case of being provided in a net shape, but is not limited to such a form, for example, a triangular truss structure or a hexagonal shape. A reinforcing layer 28 having a honeycomb structure may be provided.

  The reinforcing layer 28 is provided inside the stacked body 12. The reinforcing layer 28 is interposed between the plurality of resin layers 21. In the present embodiment, the reinforcing layer 28 is disposed between the resin layer 21A and the resin layer 21B and between the resin layer 21E and the resin layer 21F. The reinforcing layer 28 is formed simultaneously with the step of forming the wiring layer 26. The wiring layer 26G is provided in the same layer as the reinforcing layer 28 disposed between the resin layer 21A and the resin layer 21B, and the wiring layer 26K includes the reinforcing layer 28 disposed between the resin layer 21E and the resin layer 21F. It is provided in the same layer.

  The reinforcing layer 28 is made of, for example, a metal such as copper, silver, aluminum, stainless steel, nickel, or gold, or an alloy containing these metals. The reinforcing layer 28 is made of the same metal as the wiring layer 26 provided in the same layer.

  The reinforcing layer 28 is provided so as not to be connected to any other electric circuit in the laminate 12. The reinforcing layer 28 is provided without contacting any of the wiring layers 26. The periphery of the reinforcing layer 28 is surrounded by an insulating resin layer 21. The reinforcing layer 28 may be formed across a plurality of layers. Further, the reinforcing layers 28 formed over a plurality of layers may be connected by a dummy inner via.

  According to such a configuration, the wall-opening force acts as the flexible portion 120 is deformed, and the metal reinforcing layer 28 is provided on the folded portion 37 where stress is easily concentrated. Can be improved. Thereby, damage to the multilayer substrate 10 and delamination of the laminated resin layers 21 can be prevented.

  Further, since the reinforcing layer 28 is partially provided on the surface of the folded portion 37, the flexibility of the flexible portion 120 can be prevented from being greatly impaired due to the installation of the reinforcing layer 28. Furthermore, since the area | region where resin of the adjacent resin layer 21 contacts also is ensured also in the folding | returning part 37 in which the reinforcement layer 28 is provided, the delamination of the laminated resin layer 21 can be prevented more reliably.

  The reinforcing layer 28 is not connected to any other electric circuit in the stacked body 12 and is provided as a dummy wiring layer. For this reason, the durability of the flexible portion 120 can be improved without affecting the characteristics of the multilayer substrate 10.

  In the present embodiment, the reinforcing layer 28 is provided between the plurality of resin layers 21. However, the present invention is not limited to this configuration, and the reinforcing layer 28 may be provided on the surface of the laminate 12.

  Multilayer substrate 10 in the present embodiment is manufactured, for example, by a manufacturing process described below. First, a resin sheet with a copper foil is prepared. Next, the copper foil portion is etched with an acid (for example, HCl) using a resist patterned in a predetermined shape as a mask. At this time, the wiring layer 26 and the reinforcing layer 28 are formed by the same process. That is, the patterning of the wiring layer 26 and the patterning of the reinforcing layer 28 are performed by the same etching process. Next, the resist is stripped off with an alkali (for example, NaOH), and subsequently neutralized.

  Next, drilling with a laser is performed at a location corresponding to the inner via 27. The formed holes are filled with a conductive paste. Next, the laminate 12 is obtained by superposing and thermocompression bonding a plurality of resin sheets that have undergone the above steps. Finally, slits 31 are formed in the laminate 12 by laser processing, dicing processing, or punching.

  In the present embodiment, since the reinforcing layer 28 is formed by the same process as the wiring layer 26, the reinforcing layer 28 can be provided in the stacked body 12 without increasing the number of manufacturing steps of the multilayer substrate 10.

  Next, various modifications of the multilayer substrate in FIG. 2 will be described. FIG. 3 is a cross-sectional view showing a first modification of the multilayer substrate in FIG.

  With reference to FIG. 3, in this modification, the reinforcing layer 28 is provided along the inner peripheral edge of the flexible portion 120 that changes the traveling direction by 180 ° in the folded portion 37. The reinforcing layer 28 is provided in a U-shaped line shape along the inner peripheral edge of the flexible portion 120.

  According to such a configuration, the reinforcing layer 28 is provided on the inner peripheral edge of the flexible portion 120 where stress is more likely to concentrate in the folded portion 37. Thereby, the durability of the flexible portion 120 can be efficiently improved while sufficiently ensuring the flexibility.

  FIG. 4 is a sectional view showing a second modification of the multilayer substrate in FIG. Referring to FIG. 4, in the present modification, the reinforcing layer 28 is provided along the inner and outer peripheral edges of the flexible portion 120 that changes the traveling direction by 180 ° in the folded portion 37. The reinforcing layer 28 is provided in a U-shaped line shape along the inner peripheral edge and the outer peripheral edge of the flexible portion 120.

  According to such a configuration, the durability of the flexible portion 120 can be further improved while sufficiently ensuring the flexibility of the flexible portion 120.

  In addition, when the reinforcement layer 28 provided in the folding | returning part 37 is made into net shape, it becomes possible to reinforce over the whole area | region of the width direction of the flexible part 120, and the highly flexible specific site | part which is not reinforced arises. You can avoid that. For this reason, it is possible to prevent the characteristic variation from occurring due to the distance between the wires of the wiring layer 26 routed in the folded portion 37 approaching when the flexible portion 120 is deformed.

  The structure of the multilayer substrate in the first embodiment of the present invention described above will be described together. The multilayer substrate 10 in the present embodiment has a resin layer 21 made of a plurality of laminated resins having flexibility. The laminated body 12 which has is provided. The laminated body 12 is provided with a deformable flexible portion 120 that extends in a belt shape while repeatedly changing the traveling direction when viewed from the laminating direction of the resin layer 21. The flexible part 120 includes a folded part 37 at a position where the traveling direction is changed. The laminated body 12 is further provided with a metallic reinforcing layer 28 that is partially provided on the surface of the folded portion 37 when viewed from the laminating direction of the resin layer 21 and is not connected to any other electric circuit in the laminated body 12. Have.

  According to the multilayer substrate 10 according to Embodiment 1 of the present invention configured as described above, the multilayer substrate 10 can be obtained by improving the durability of the flexible portion 120 while sufficiently ensuring the flexibility of the flexible portion 120. Damage and delamination of the laminated resin layer 21 can be prevented.

(Embodiment 2)
FIG. 5 is a cross-sectional view showing a multilayer substrate according to Embodiment 2 of the present invention. FIG. 6 is a cross-sectional view showing the multilayer substrate along the line VI-VI in FIG. FIG. 5 shows a cross section of the multilayer substrate along the line VV in FIG. The multilayer substrate in the present embodiment basically has the same structure as that of the multilayer substrate 10 in the first embodiment. Hereinafter, the description of the overlapping structure will not be repeated.

  With reference to FIG. 5 and FIG. 6, in the present embodiment, a laminated body 12 is provided with a main body portion 110, a flexible portion 120, and a pad portion 130. A flexible part 120 is provided on both sides of the main body part 110, and a pad part 130 is provided at a position where the periphery is taken into the flexible part 120.

  The flexible portion 120 extends in a band shape while repeatedly changing the traveling direction by 90 ° as viewed from the stacking direction of the stacked body 12, and has a spiral shape as a whole. The flexible part 120 has, as its constituent parts, a folded part 37 disposed at a position where the traveling direction is changed, and an intermediate part 36 that connects between adjacent folded parts 37.

  The folded portion 37 and the intermediate portion 36 are alternately provided between the main body portion 110 and the pad portion 130. Folded portions 37 and intermediate portions 36 are alternately arranged from the main body portion 110 to the pad portion 130 while turning in a rectangular shape. The folding | returning part 37 is arrange | positioned at the corner | angular part which turns in the rectangular shape, and the intermediate part 36 is arrange | positioned at the linear part between adjacent corner | angular parts.

  The laminated body 12 is formed with a slit 31 for providing the deformable flexible portion 120. The slit 31 penetrates in the laminating direction of the resin layer 21. The slit 31 extends while repeatedly changing the traveling direction by 90 ° when viewed from the stacking direction of the stacked body 12. The slit 31 is formed so that the flexible portions 120 adjacent to the spiral inner peripheral side and the outer peripheral side are separated from each other.

  In the multilayer substrate in the present embodiment, a metal reinforcing layer 28 is provided on the folded portion 37. The reinforcing layer 28 is provided in a net shape on the surface of the folded portion 37 when viewed from the lamination direction of the resin layer 21. In addition, the form in which the reinforcing layer 28 is provided is the same as in the first embodiment.

  FIG. 7 is a cross-sectional view showing a first modification of the multilayer substrate in FIG. Referring to FIG. 7, the multilayer substrate in the present modification is provided with reinforcing layer 28 in the same form as the multilayer substrate in FIG. 3 in the first embodiment.

  That is, the reinforcing layer 28 is provided along the inner peripheral edge of the flexible portion 120 that changes the 90 ° traveling direction in the folded portion 37. The reinforcing layer 28 is provided in an L-shaped line shape along the inner peripheral edge of the folded portion 37.

  FIG. 8 is a cross-sectional view showing a second modification of the multilayer substrate in FIG. Referring to FIG. 8, the multilayer substrate in the present modification is provided with reinforcing layer 28 in the same form as the multilayer substrate in FIG. 4 in the first embodiment.

  That is, the reinforcing layer 28 is provided along the inner peripheral edge and the outer peripheral edge of the flexible part 120 that changes the traveling direction of 90 ° in the folded part 37. The reinforcing layer 28 is provided in an L-shaped line shape along the inner and outer peripheral edges of the folded portion 37.

  According to the multilayer substrate according to the second embodiment of the present invention configured as described above, the effects described in the first embodiment can be similarly obtained.

  In the first and second embodiments described above, the flexible portion 120 extending in a strip shape while repeatedly changing the traveling direction by 180 ° or 90 ° has been described. However, the present invention is not limited to this, and the flexible portion 120 is It may extend in a band shape while changing by another angle (for example, 60 °).

(Embodiment 3)
FIG. 9 is a plan view showing a multilayer substrate according to Embodiment 3 of the present invention. The multilayer substrate in the present embodiment basically has the same structure as that of the multilayer substrate 10 in the first embodiment. Hereinafter, the description of the overlapping structure will not be repeated.

  Referring to FIG. 9, in multilayer substrate in the present embodiment, laminated body 12 is provided with main body portion 110, flexible portion 120, and pad portion 130. The flexible part 120 extends linearly from the periphery of the main body part 110. The pad part 130 is provided at the tip of the flexible part 120 extending from the main body part 110.

  In the drawing, the structure in which the flexible part 120 extends from one place of the main body part 110 is shown, but the structure in which the flexible part 120 extends from a plurality of places in the main body part 110 is also possible. Good.

  The flexible part 120 extends in a strip shape while repeatedly changing the traveling direction as seen from the stacking direction of the resin layer 21 and has a wave shape as a whole. The flexible part 120 has, as its constituent parts, a folded part 37 disposed at a position where the traveling direction is changed, and an intermediate part 36 that connects between adjacent folded parts 37. The flexible portion 120 may have a wave shape that extends in a curved shape in the folded portion 37 and linearly extends in the intermediate portion 36, or extends in a curved shape in the folded portion 37, and extends in a curved shape in the intermediate portion 36. It may have a wave shape.

  In the multilayer substrate in the present embodiment, a metal reinforcing layer 28 is provided on the folded portion 37. The reinforcing layer 28 is provided in a net shape on the surface of the folded portion 37 when viewed from the lamination direction of the resin layer 21. In addition, the form in which the reinforcing layer 28 is provided is the same as in the first embodiment.

  According to the multilayer substrate in the third embodiment of the present invention configured as described above, the effects described in the first embodiment can be similarly obtained.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention is mainly applied to a multilayer substrate having flexibility.

  DESCRIPTION OF SYMBOLS 10 Multilayer board | substrate, 12 laminated body, 12a, 12b edge, 21, 21A, 21B, 21C, 21D, 21E, 21F resin layer, 26, 26G, 26H, 26I, 26J, 26K wiring layer, 27 inner via, 28 reinforcement Layer, 31, 31p, 31q, 31r Slit, 36 Middle part, 37 Folded part, 110 Body part, 120 Folded part, 130 Pad part.

Claims (8)

A laminate having a resin layer made of a plurality of flexible resins laminated,
The laminate is provided with a deformable flexible portion that extends in a band shape while repeatedly changing the traveling direction as seen from the lamination direction of the resin layer,
The flexible portion includes a folded portion at a position where the traveling direction is changed,
The laminated body is further provided with a metallic reinforcing layer that is partially provided on the surface of the folded portion when viewed from the laminating direction of the resin layer and is not connected to any other electric circuit in the laminated body. And
The reinforcing layer is formed across a plurality of the resin layers,
The multilayer body further includes a dummy inner via that connects the reinforcing layers formed across a plurality of the resin layers .   The multilayer substrate according to claim 1, wherein the reinforcing layer is interposed between a plurality of the resin layers.   The multilayer substrate according to claim 1, wherein the reinforcing portion is provided in a net shape.   4. The multilayer substrate according to claim 1, wherein the flexible portion extends in a band shape while repeatedly reversing the traveling direction by 180 ° so as to form a meander shape as a whole.   5. The multilayer substrate according to claim 1, wherein the flexible portion extends in a band shape while repeatedly changing a traveling direction by 90 ° so as to form a spiral shape as a whole.   The multilayer substrate according to claim 4, wherein the reinforcing layer is provided along an inner peripheral edge of the flexible portion that changes a traveling direction in the folded portion.   The multilayer substrate according to claim 6, wherein the reinforcing layer is further provided along an outer peripheral edge of the flexible portion that changes a traveling direction in the folded portion.   The multilayer substrate according to claim 1, wherein the multilayer body further includes a wiring layer provided in the same layer as the reinforcing layer.

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