Circuit board, and method for manufacturing mounting board

Abstract

To provide a circuit board that can prevent faulty connection between a joint material of the circuit board and an electronic part, and a method for manufacturing a mounting board.SOLUTION: An inner wall 9 has at least one groove part 30 that penetrates from an inner peripheral surface 13a to an outer peripheral surface 13b. In this case, when an electronic part 2 is mounted on a circuit board 3, an excess component 20 can be discharged to the outside of the inner wall 9 through the groove part 30. Consequently, the electronic part 2 can be sufficiently pushed into a cavity 11 and brought into contact with a joint material 4 through a pressure step using a pressure reflow device. An outer wall 40 of insulating material erected from a base material 8 in a height direction is provided on an outer peripheral side of the inner wall 9 so as to surround the cavity 11. The outer wall 40 can thus intercept the excess component 20 discharged through the groove part 30, and can thereby prevent the component 20 from spreading on a principal surface 8a of the base material 8.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a circuit board and a mounting board.

Background Art

[0002] In recent years, with the progress of electronization, the development of technologies for mounting electronic components on a substrate has advanced. For example, technologies for mounting a large number of bare chips of semiconductor light-emitting elements typified by light-emitting diodes (hereinafter referred to as "LEDs") used in lighting, display devices, etc. on a wiring board have been developed. For example, Patent Document 1 discloses an invention in which semiconductor light-emitting elements are inserted and joined into a cavity in which a plurality of semiconductor light-emitting elements can be easily positioned and arranged. Further, in Patent Document 2, technologies for suppressing the carry-over and solder bridging of semiconductor light-emitting elements in the mounting of electronic components using a paste-like joining material have also been developed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, in a circuit board, terminals and a bonding material may be disposed inside the wall of an insulating material. For such a circuit board, a constituent material is filled inside the wall, an electronic component is mounted using a holding member, and the electronic component is pushed into the inside of the wall and heated using a pressure reflow device and bonded to the circuit board to mount the electronic component. At this time, due to surplus constituent material remaining in the wall and on the upper part of the wall around the electronic component, the electronic component cannot be sufficiently pushed in during the pressurization process using the pressure reflow device, and there is a possibility of a connection failure occurring between the bonding material of the circuit board and the electronic component. On the other hand, if the constituent material overflows and spreads on the base material, there is a problem that the surface of the base material is contaminated.

[0005] An object of the present disclosure is to provide a circuit board and a method for manufacturing a mounting board that can suppress connection failures between the circuit board and the electronic component and can suppress contamination of the base material.

Means for Solving the Problems

[0006] The circuit board according to the present disclosure is a circuit board including a base material, at least a pair of terminals provided on the base material, a bonding material containing a metal element disposed on the terminals, and an inner wall of an insulating material rising in a height direction perpendicular to the main surface of the base material from the base material, wherein the pair of terminals and the bonding material are disposed in a cavity formed in the wall, at least one groove portion penetrating from the inner peripheral surface to the outer peripheral surface is formed in the inner wall, and an outer wall of an insulating material rising in the height direction from the base material is provided on the outer peripheral side of the inner wall so as to surround the cavity.

[0007] The method for manufacturing a mounting board according to the present disclosure is a method for manufacturing a mounting board by mounting an electronic component on the above-described circuit board, wherein a constituent material may be disposed on the base material, the electronic component may be disposed, and then the electronic component may be bonded to the terminals using a pressure reflow device.

Effects of the Invention

[0008] According to the present disclosure, it is possible to provide a circuit board and a method for manufacturing a mounting board that can suppress connection failures between the circuit board and the electronic component and can suppress contamination of the base material.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

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Figure 8

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Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

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Figure 17

Figure 18

Figure 19

Figure 20

Mode for Carrying Out the Invention

[0010] Referring to FIGS. 1 to 3, the circuit board 3 according to the embodiment of the present disclosure will be described. FIG. 1 is a schematic cross-sectional view showing a mounting substrate 1 including the circuit board 3 according to the embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view showing the circuit board 3 according to the embodiment of the present disclosure. FIG. 3 is a plan view of the circuit board 3.

[0011] As shown in FIG. 1, the mounting substrate 1 includes an electronic component 2 and a circuit board 3. The mounting substrate 1 is configured by mounting the electronic component 2 on the circuit board 3 via a bonding material 4.

[0012] The electronic component 2 includes a main body portion 6 and a pair of terminals 7. The main body portion 6 is a member for exerting the function as the electronic component 2. The terminal 7 is a metal portion formed on the main surface of the main body portion 6. As the material of the terminal 7, metals such as Cu, Ti, Au, Ni, Sn, Bi, P, B, In, Ag, Zn, Pd, Mo, Pt, Cr, or an alloy selected from at least two of these may be adopted. The electronic component 2 is composed of, for example, a micro LED or the like. The micro LED is a component that emits light in response to an input from the circuit board 3.

[0013] The circuit board 3 includes a base material 8, an inner wall 9, an outer wall 40, and a pair of terminals 10 (a first terminal and a second terminal). The base material 8 is a flat main body portion of the circuit board 3. The base material 8 has a main surface 8a. As the base material 8, a printed circuit board for mounting each conductor pattern and each electronic component on the circuit board 3 on the main surface 8a may be adopted. As the material of the base material 8, a known resin material or ceramic material used for a printed circuit board may be adopted. In the following description, the description may be made using the XYZ coordinates set for the circuit board 3. The X-axis direction (second direction) is a direction parallel to the main surface 8a of the base material 8, the Y-axis direction (third direction) is a direction parallel to the main surface 8a of the base material 8 and orthogonal to the X-axis direction, and the Z-axis direction (first direction, height direction) is a direction orthogonal to the main surface 8a of the base material 8.

[0014] The inner wall 9 of the insulating material is provided on the main surface 8a of the base material 8. The inner wall 9 protrudes from the base material 8 toward the positive side in the Z-axis direction. As shown in FIG. 3, in the present embodiment, the inner wall 9 has wall frame portions 13A, 13B, 13C, and 13D provided on four sides. The wall frame portions 13A and 13B face each other in a state of being separated from each other in the X-axis direction and extend in parallel in the Y-axis direction. The wall frame portion 13A is arranged on the positive side in the X-axis direction, and the wall frame portion 13B is arranged on the negative side. The wall frame portions 13C and 13D face each other in a state of being separated from each other in the Y-axis direction and extend in parallel in the X-axis direction. The wall frame portion 13C is arranged on the positive side in the Y-axis direction, and the wall frame portion 13D is arranged on the negative side. The wall frame portion 13A connects the ends of the wall frame portions 13C and 13D on the positive side in the X-axis direction. The wall frame portion 13B connects the ends of the wall frame portions 13C and 13D on the negative side in the X-axis direction. Thereby, when viewed from the height direction, the inner wall 9 has a rectangular frame-like structure. The wall frame portions 13A and 13B constitute the short sides, and the wall frame portions 13C and 13D constitute the long sides. Although the dimensions are not particularly limited, the dimension of the wall frame portions 13A and 13B in the Y-axis direction may be set to 10 μm to 60 μm. The dimension of the wall frame portions 13C and 13D in the X-axis direction may be set to 15 μm to 70 μm. The dimension of the short side of the inner peripheral surface inside the inner wall 9 may be set to be 8 μm or more and 44 μm or less. The dimension of the long side of the inner peripheral surface inside the inner wall 9 may be 15 μm or more and 68 μm or less. The dimension of the short side of the inner peripheral surface inside the inner wall 9 is the dimension in the Y-axis direction between the inner peripheral surface 13a of the wall frame portion 13C and the inner peripheral surface 13a of the wall frame portion 13D. The dimension of the long side of the inner peripheral surface inside the inner wall 9 is the dimension in the X-axis direction between the inner peripheral surface 13a of the wall frame portion 13A and the inner peripheral surface 13a of the wall frame portion 13B. As the material of the inner wall 9, for example, resin materials such as epoxy resin, acrylic resin, phenolic resin, melamine resin, urea resin, and alkyd resin are adopted. Particularly preferably, epoxy resin and acrylic resin are adopted as the material of the inner wall 9.

[0015] The outer wall 40 of the insulating material is provided on the main surface 8a of the base material 8. The inner wall 9 protrudes from the base material 8 toward the positive side in the Z-axis direction. The outer wall 40 is formed on the outer peripheral side of the inner wall 9 so as to surround the cavity 11. As shown in FIG. 3, in the present embodiment, the outer wall 40 has wall frame portions 41A, 41B, 41C, and 41D provided on four sides. The wall frame portions 41A and 41B face each other in a state of being separated from each other in the X-axis direction and extend in parallel in the Y-axis direction. The wall frame portion 41A is arranged on the positive side in the X-axis direction, and the wall frame portion 41B is arranged on the negative side. The wall frame portion 41A faces the wall frame portion 13A of the inner wall 9 while being separated from it on the positive side in the X-axis direction. The wall frame portion 41B faces the wall frame portion 13B of the inner wall 9 while being separated from it on the negative side in the X-axis direction. The wall frame portions 41C and 41D face each other in a state of being separated from each other in the Y-axis direction and extend in parallel in the X-axis direction. The wall frame portion 41C is arranged on the positive side in the Y-axis direction, and the wall frame portion 41D is arranged on the negative side. The wall frame portion 41C faces the wall frame portion 13C of the inner wall 9 while being separated from it on the positive side in the Y-axis direction. The wall frame portion 41D faces the wall frame portion 13D of the inner wall 9 while being separated from it on the negative side in the Y-axis direction. The wall frame portion 41A connects the ends of the wall frame portions 41C and 41D on the positive side in the X-axis direction. The wall frame portion 41B connects the ends of the wall frame portions 41C and 41D on the negative side in the X-axis direction. As a result, the outer wall 40 has a rectangular frame-like structure when viewed from the height direction. The wall frame portions 41A and 41B form the short sides, and the wall frame portions 41C and 41D form the long sides. Note that the dimensions of the outer wall 40 in the XY plane are not particularly limited, as long as they satisfy the relationship of the volume described later with the inner wall 9 and the like. The material of the outer wall 40 may be the same as that described for the inner wall 9. However, depending on the manufacturing process, different materials may be used for the outer wall 40 and the inner wall 9.

[0016] As shown in FIGS. 1 to 3, the terminal 10 is a metal part provided on the main surface 8a of the base material 8. As the material of the terminal 10, Ni, Cu, Ti, Cr, Al, Mo, Pt, Au, or an alloy selected from at least two of these is adopted. A conductive film 12 is formed on the upper surface of the terminal 10. As the material of the conductive film 12, films such as Ti, Cu, Ni, Al, Mo, Cr, Ag, or films in which metal particles and a binder are mixed are adopted.

[0017] The bonding material 4 is a member that bonds the terminal 7 of the electronic component 2 and the terminal 10 of the circuit board 3. The bonding material 4 is configured by thermally bonding and integrating the bonding material 4A on the circuit board 3 side and the bonding material 4B on the electronic component 2 side (see FIG. 8). The bonding material 4 may contain Sn or may be composed of an alloy containing Sn. However, the bonding material 4 is not necessarily limited to those containing Sn. The bonding material 4 may be composed of an alloy containing an element that lowers the melting point of Sn in addition to Sn. Examples of the element that lowers the melting point of Sn include Bi. The bonding material 4 functions as solder. As a result, between the base material 8 and the main body 6, in order from the upper surface of the base material 8, the terminal 10, the conductive film 12, the bonding material 4, and the terminal 7 are laminated. Note that at this location, after the terminal 10, the conductive film 12, the bonding material 4, and the terminal 7 are laminated, soldering is performed. Therefore, after soldering, a structure in which the metals of the terminal 10, the conductive film 12, the bonding material 4, and the terminal 7 are melted and diffused is formed. Such a structure after soldering may be a structure containing brittle intermetallic compounds (IMCs). When there are brittle intermetallic compounds, it is easy to break due to external stress, so the reliability tends to decrease. Therefore, by surrounding the electronic component 2 with the inner wall 9, the effect of protecting the electronic component 2 appears.

[0018] A cavity 11 is formed in the inner wall 9. The cavity 11 is constituted by a through hole that penetrates the inner wall 9 in the height direction. As a result, the upper surface of the base material 8 is exposed on the bottom side of the cavity 11. The cavity 11 is rectangular when viewed from the height direction (see FIG. 3). The terminal 7, the terminal 10, the conductive film 12, and the bonding material 4 are arranged in the cavity 11 surrounded by the inner wall 9, and thus are surrounded by the inner wall 9 on all sides. A slight gap is formed between the terminal 7, the terminal 10, the conductive film 12, and the bonding material 4 and the inner peripheral surface 13a of the four wall frame portions 13A, 13B, 13C, 13D that constitute the cavity 11.

[0019] Inside the cavity 11, a structural member 20 is disposed between the electronic component 2 and the bonding material 4 and the inner wall 9. By supporting with the structural member 20, the electronic component 2 can be made difficult to peel off from the circuit board 3. Further, the forces applied to the electronic component 2, the bonding material 4, and the terminals 7 and 10 are alleviated, and the reliability can be improved. As the material of the structural member 20, for example, epoxy resin, acrylic resin, phenolic resin, melamine resin, urea resin, alkyd resin, or a mixture thereof, or a mixture of the resin material and SiOx, ceramics, etc. is adopted. Particularly preferably, epoxy resin and acrylic resin are adopted as the material of the structural member 20. The viscosity of the structural member 20 during filling is preferably 1 Pa to 20 Pa, and more preferably 5 Pa to 10 Pa.

[0020] As shown in FIG. 2, the circuit board 3 has a configuration in which the electronic component 2 and the structural member 20 are removed from the mounting board 1 shown in FIG. 1. In the circuit board 3, a bonding material 4A containing a metal element is disposed on the upper side (the upper surface of the conductive film 12) of the terminal 10. The circuit board 3 includes a bonding material 4A (first bonding material) on the side in the X-axis direction disposed on the terminal 10 and a bonding material 4A (second bonding material) on the negative side in the X-axis direction disposed on the terminal 10. These bonding materials 4A constitute a part of the bonding material 4 in the stage before thermally bonding the electronic component 2 and the mounting board 1 as described above. In the state of the circuit board 3, the pair of terminals 10, the conductive film 12, and the bonding material 4A are disposed inside the inner wall 9 formed of an insulating material.

[0021] As shown in FIG. 3, the wall frame portions 13A, 13B, 13C, and 13D each have at least one groove portion 30 that penetrates from the inner peripheral surface 13a to the outer peripheral surface 13b. For the wall frame portions 13A and 13B, the X-axis direction is the thickness direction. Therefore, the groove portion 30 of the wall frame portions 13A and 13B extends in the X-axis direction and penetrates the wall frame portions 13A and 13B. For the wall frame portions 13C and 13D, the Y-axis direction is the thickness direction. Therefore, the groove portion 30 of the wall frame portions 13C and 13D extends in the Y-axis direction and penetrates the wall frame portions 13C and 13D. Note that the groove portion 30 only needs to be formed in at least one of the wall frame portions 13A, 13B, 13C, and 13D. Also, a plurality of groove portions 30 may be formed in any of the wall frame portions 13A, 13B, 13C, and 13D. Further, groove portions 30 may be formed at the corners of each of the wall frame portions 13A, 13B, 13C, and 13D (details will be described later).

[0022] Next, with reference to FIG. 4, the configuration of the wall frame portion 13D when viewed from the thickness direction will be described. FIG. 4(a) is a view of the wall frame portion 13D viewed from the Y-axis direction, which is the thickness direction. Although the wall frame portion 13D is shown in FIG. 4, the same explanation also applies to the other wall frame portions 13A, 13B, and 13C. As shown in FIG. 4(a), when viewed from the Y-axis direction, which is the thickness direction of the wall frame portion 13D, the groove portion 30 extends from the tip portion 13c in the height direction (Z-axis direction in this embodiment) of the wall frame portion 13D toward the base material 8 side (negative side in the Z-axis direction). The groove portion 30 has a bottom surface 30a and a pair of side surfaces 30b. The bottom surface 30a is formed on the negative side in the Z-axis direction from the tip portion 13c. The pair of side surfaces 30b extend from both ends in the X-axis direction of the bottom surface 30a to the tip portion 13c. In the example shown in FIG. 4(a), the groove portion 30 reaches the main surface 8a of the base material 8. In this case, the main surface 8a of the base material 8 constitutes the bottom surface 30a of the groove portion 30. In this configuration, the region on the negative side in the X-axis direction and the region on the positive side in the X-axis direction of the wall frame portion 13D are separated by the groove portion 30.

[0023] As shown in FIG. 4(b), the width of the groove portion 30 in the X-axis direction, which is the width direction, is larger on the tip portion 13c side than on the bottom surface 30a side. The width of the groove portion 30 at the tip portion 13c is larger than the width of the groove portion 30 at the bottom surface 30a. In the example shown in FIG. 4(b), the groove portion 30 opens widely in the X-axis direction as it goes toward the tip portion 13c side. The pair of side surfaces 30b are inclined so that the distance between them increases as they go toward the positive side in the Z-axis direction.

[0024] As shown in FIG. 4(c), the bottom surface 30a of the groove portion 30 may be disposed at a position separated from the base material 8. A member of the wall frame portion 13D exists between the bottom surface 30a and the main surface 8a of the base material 8. Note that the height dimension of the groove portion 30 when the bottom surface 30a is separated from the base material 8 is not particularly limited and may be 1 μm or more.

[0025] Note that the width of the groove portion 30 is not particularly limited as long as it is not excessively small for discharging the excess structural material 20. For example, the width of the groove portion 30 may be 1 μm or more, and may be 4 μm or more. Note that the wall frame portion 13 only needs to be large enough to position the electronic component 2, and the width of the groove portion 30 may be set large (see, for example, FIG. 17(d)). Even in this case, the necessary structural material 20 can be held and the excess can be discharged. Further, when the bottom surface 30a is disposed at a position separated from the base material 8, the bottom surface 30a may be curved.

[0026] The relationship between the sizes of the inner wall 9 and the outer wall 40 will be described. As shown in FIG. 2, the relationship between the thickness Ti of the inner wall 9 and the thickness To of the outer wall 40 is not particularly limited. In the case of the outer wall 40 formed of a continuous insulating material (approximately uniformly formed) covering the main surface 8a of the base material 8 as described later, the thickness To becomes very large. In the case of the frame-shaped outer wall 40 as shown in FIGS. 1 to 3, the thickness Ti of the inner wall 9 may be equal to or greater than the thickness To of the outer wall 40. The thicknesses Ti and To are the dimensions in the X-axis direction of the wall frame portions 13A, 13B, 41A, and 41B. The thicknesses Ti and To are the dimensions in the Y-axis direction of the wall frame portions 13C, 13D, 41C, and 41D. Although not particularly limited, the thickness Ti of the inner wall 9 may be set to 1 μm or more and equal to or less than the height Hi of the inner wall 9. The thickness To of the outer wall 40 may be set to 1 μm or more and equal to or less than the height Ho of the outer wall 40. Note that, as described later, the cross-sectional shapes of the wall frame portions 13A, 13B, 13C, 13D, 41A, 41B, 41C, and 41D may not be constant in the height direction (see, for example, FIG. 5(a)), and when comparing the thicknesses Ti and To, the thickness at the bottom, that is, the position of the base material 8, may be compared.

[0027] The height Hi of the inner wall 9 may be equal to or greater than the height Ho of the outer wall 40. The heights Hi and Ho are the dimensions in the height direction of the wall frame portions 13A, 13B, 13C, 13D, 41A, 41B, 41C, and 41D. Although not particularly limited, the height Hi of the inner wall 9 may be set to 4 μm or more and 10 μm or less. The height Ho of the outer wall 40 may be set to 1 μm or more and equal to or less than the height Hi of the inner wall 9. When the heights of the tip portions 13c and 41c of each wall are not uniform, the heights Hi and Ho are defined by the maximum height.

[0028] As shown in FIG. 3, when viewed from the height direction, a reference shape T1 in the form of a rectangle with the minimum area circumscribing the inner peripheral surface 13a of the cavity 11 of the inner wall 9 is set. When viewed from the height direction, a reference shape T2 in the form of a rectangle with the maximum area inscribed in the outer peripheral surface 13b of the inner wall 9 is set. In the present embodiment, the reference shapes T1 and T2 are rectangular. These reference shapes T1 and T2 are virtually set and are shown by virtual lines in FIG. 3. Let the volume obtained by multiplying the height Hi (see FIG. 2) of the inner wall 9 by the reference shape T1 be the volume S1 in the cavity 11.

[0029] A rectangular annular space SP is formed between the inner wall 9 and the inner peripheral surface 41a of the outer wall 40. The structural member 20 discharged from the cavity 11 is accommodated in the space SP. The area of the space SP when viewed from the height direction is the area of the region between the rectangle drawn by the inner peripheral surface 41a of the outer wall 40 and the reference shape T2 on the outer peripheral side of the inner wall 9. The height of the space SP is the lower height of the inner wall 9 and the outer wall 40. In the example shown in FIG. 2, the relationship between the heights of the inner wall 9 and the outer wall 40 is "Hi≧Ho". The region lower than the reference position SP1 indicating the height Ho of the outer wall 40 becomes the space SP. Therefore, the volume of the space SP obtained by multiplying the area by the height Ho of the outer wall 40 is defined as S2.

[0030] As shown in FIG. 1, an electronic component 2 is mounted in the cavity 11. This electronic component 2 is a member that extrudes the structural member 20 that filled the cavity 11 before joining. The maximum volume of the extruded structural member 20 may be regarded as the volume occupied by the electronic component 2 in the cavity 11 after joining. Among the electronic component 2, the volume of the portion that enters the cavity 11, that is, the region (referred to as PE) disposed at a position lower than the tip 9a of the inner wall 9, is defined as the volume occupied by the electronic component 2 in the cavity 11, and such a volume is defined as S3.

[0031] As described above, let the volume in the cavity 11 be S1, the volume of the space SP between the inner wall 9 and the outer wall 40 be S2, and the volume occupied by the electronic component mounted in the cavity 11 be S3. At this time, S2 may be less than or equal to S1 (S2≦S1). Also, S2 may be greater than or equal to S3 (S2≧S3).

[0032] Here, as shown in FIG. 5(a), at least one of the surfaces extending in the height direction of the inner wall 9 and the outer wall 40 has a recess 45 at a position on the base material 8 side in the height direction. A cavity material 46 covering the base material 8 may be provided at the position of the recess 45. The surfaces extending in the height direction on the inner wall 9 are the inner peripheral surface 13a, the outer peripheral surface 13b, and the side surface 30b of the groove portion 30. The surfaces extending in the height direction on the outer wall 40 are the inner peripheral surface 41a and the outer peripheral surface 41b. Any of these surfaces 13a, 13b, 30b, 41a, 41b may have the recess 45. Further, the recess 45 does not have to be provided over the entire area of each of the surfaces 13a, 13b, 30b, 41a, 41b, and may be provided partially. The recess 45 is formed at a position closer to the base material 8 than the tip portions 13c, 41c in the height direction. The recess 45 is formed at a position spaced upward from the main surface 8a of the base material 8. Thus, the cavity material 46 is formed between the recess 45 and the main surface 8a of the base material 8. The recess 45 may extend in a direction in which the surfaces 13a, 13b, 30b, 41a, 41b extend along the planar direction of the base material 8. For example, when the inner peripheral surface 13a of the wall frame portion 13A has the recess 45, the recess 45 may be formed to extend in the Y-axis direction. Also, when the side surface 30b of the groove portion 30 of the wall frame portion 13A has the recess 45, the recess 45 may be formed to extend in the X-axis direction.

[0033] The opening width of the recess 45, that is, the dimension w1 in the height direction of the opening portion is not particularly limited, but may be set to 0 μm or more and 3 μm or less. The thickness of the cavity material 46, that is, the dimension w2 in the height direction is not particularly limited, but may be set to 0 μm or more and 1 μm or less. The depth dimension D1 of the recess 45 is not particularly limited, but may be set to 0 μm or more and 3 μm or less. In the example shown in FIG. 5(b), the recess 45 is formed directly above the base material 8 and the cavity material 46 is not formed. Such a structure is not preferable because the bonding strength between the walls 9, 40 and the base material 8 decreases, and the structure of FIG. 5(a) is more preferable. However, the structure as shown in FIG. 5(b) is not excluded.

[0034] Referring to FIG. 6, the cross-sectional shape of the frame-shaped outer wall 40 will be described. Let the thickness at the tip 41c in the height direction of the wall frame portion 41 of the outer wall 40 be Tto, the thickness at the end 41d on the base material 8 side be Tbo, and the height of the wall frame portion of the outer wall be Ho. When the end 41d on the base material 8 side as shown in FIG. 6 has a tapered shape thicker than the tip 41c, the condition of the tapered shape where Tbo is equal to or greater than Tto and equal to or greater than Ho is satisfied. In addition, in the case of the shape as shown in FIG. 5(b), the tip 41c may be thicker than the end 41d on the base material 8 side. In this case, the condition of the tapered shape where Tto is equal to or greater than Tbo and equal to or greater than Ho may be satisfied.

[0035] Referring to FIGS. 7 and 8, the manufacturing method of the circuit board 3 and the mounting board 1 will be described. First, as shown in FIG. 7(a), terminals 10 are formed on the upper surface of the base material 8. Next, as shown in FIG. 7(b), an inner wall 9 and an outer wall 40 are formed on the base material 8. Thereby, the circuit board 3 is completed. In FIG. 7(b), a conductive film 12 and a bonding material 4A are formed on the upper surface of the terminal 10. Next, as shown in FIG. 7(c), by filling the cavity 11 with the constituent material 20, the constituent material 20 is arranged on the base material 8. Then, the electronic component 2 is held by a holding member and the electronic component 2 is mounted in the cavity 11. Next, as shown in FIG. 8, the electronic component 2 is pushed into the cavity 11 by a pressure reflow device 49 with respect to the electronic component 2, and the bonding material 4A and the bonding material 4B are brought into contact with each other inside the constituent material 20. At this time, a part of the constituent material 20 is pushed out into the groove portion 30 (see FIG. 3). At this time, the pushed-out constituent material 20 is received in the space SP between the outer wall 40 and the inner wall 9. Next, by heating, the bonding material 4B of the electronic component 2 and the bonding material 4A of the base material 8 are bonded. Thereby, the mounting board 1 is completed.

[0036] Next, referring to FIG. 9, the method for forming the inner wall 9 and the outer wall 40 having the groove portion 30 will be described. First, as shown in FIG. 9(a), the inner wall 9 and the outer wall 40 are formed on the base material 8. Next, as shown in FIG. 9(b), by irradiating the inner wall 9 with a laser using a laser device 51, a part of the inner wall 9 is processed. Thereby, as shown in FIG. 9(c), the groove portion 30 is formed in the inner wall 9.

[0037] Alternatively, as shown in FIG. 9(d), a resist 52 is formed on the substrate 8. Next, as shown in FIG. 9(e), exposure is performed using a glass mask 53 having a pattern corresponding to the shape of the inner wall 9 having the groove portion 30 and the shape of the outer wall 40. As shown in FIG. 9(f), by developing the exposed resist 52, the inner wall 9 having the groove portion 30 and the outer wall 40 are formed.

[0038] Next, the operation and effects of the manufacturing method of the circuit board 3 and the mounting board 1 according to the present embodiment will be described.

[0039] First, with reference to FIG. 10, a circuit board 103 according to a comparative example will be described. The inner wall 9 of the circuit board 103 does not have the groove portion 30 and the outer wall 40 described above. After filling the inside of the inner wall 9 with the constituent material 20 and using a holding member to mount the electronic component 2 inside the inner wall 9, when attempting to push the electronic component 2 with a pressure reflow device, due to the influence of the excess constituent material 20, the electronic component 2 cannot be pushed in sufficiently. In this case, reflow is performed with the bonding material 4B of the electronic component 2 and the bonding material 4A of the circuit board 3 remaining separated, and there is a possibility of a connection failure between the bonding material 4A of the circuit board 3 and the electronic component 2.

[0040] On the other hand, in the circuit board 3 according to the present embodiment, a pair of terminals 10 (a first terminal and a second terminal) are arranged in a cavity 11 surrounded by an inner wall 9. Here, the inner wall 9 has at least one groove portion 30 penetrating from an inner peripheral surface 13a to an outer peripheral surface 13b. In this case, when a constituent member 20 is arranged in the cavity 11, an electronic component 2 is mounted using a holding member, and the electronic component 2 is pushed into the inside of the cavity 11 and heated using a pressure reflow device to be joined to the circuit board 3, the excess constituent member 20 can be discharged to the outside of the inner wall 9 through the groove portion 30. Thereby, in the pressurizing step using the pressure reflow device, the electronic component 2 can be sufficiently pushed into the cavity 11 and brought into contact with the bonding material 4. Further, on the outer peripheral side of the inner wall 9, an outer wall 40 of an insulating material rising from the base material 8 in the Z-axis direction (the first direction) is provided so as to surround the cavity 11. Therefore, since the outer wall 40 can block the excess constituent member 20 discharged through the groove portion 30, it is possible to suppress the spread of the constituent member 20 on the main surface 8a of the base material 8. As described above, it is possible to suppress a connection failure between the bonding material 4 and the electronic component 2 of the circuit board 3 and to suppress contamination of the base material 8.

[0041] The circuit board 3 may include a bonding material 4A (a first bonding material) containing a metal element disposed on the terminal 10A and a bonding material 4A (a second bonding material) containing a metal element disposed on the terminal 10B. In this case, the electronic component 2 can be mounted on the terminals 10A and 10B via the bonding material 4A.

[0042] The height Hi of the inner wall 9 may be equal to or greater than the height Ho of the outer wall 40. In this case, by increasing the height of the inner wall 9, it is possible to easily pressurize the electronic component 2 with respect to the cavity 11 of the inner wall 9.

[0043] When the volume of the space between the inner wall 9 and the outer wall 40 is S2 and the volume occupied by the electronic component mounted in the cavity is S3, S2 may be equal to or greater than S3. In this case, the space SP between the outer wall 40 and the inner wall 9 can secure a volume necessary for receiving the constituent member 20 discharged from the cavity 11.

[0044] In any of the surfaces extending in the Z-axis direction of at least one of the inner wall 9 and the outer wall 40, a recess 45 may be formed at a position on the base material 8 side in the Z-axis direction, and a cavity material 46 covering the base material 8 may be provided at the position of the recess 45. According to such a shape, the recess 45 can function as a guide groove through which the constituent member 20 passes at the position on the base material 8 side. Therefore, the fluidity of the constituent member 20 can be improved.

[0045] When the thickness at the tip 41c in the Z-axis direction of the wall frame portion 41 of the outer wall 40 is Tto, the thickness at the end portion 41d on the base material side is Tbo, and the height of the wall frame portion 41 of the outer wall 40 is Ho, a taper shape condition where Tbo is equal to or greater than Tto and equal to or greater than Ho may be satisfied. When the outer wall 40 is formed in a frame shape, such a configuration may be adopted.

[0046] When viewed from the thickness direction of the wall frame portion 13 of the inner wall 9, the groove portion 30 extends from the tip of the wall frame portion 13 in the Z-axis direction toward the base material 8 side, and the width of the groove portion 30 in the width direction orthogonal to the thickness direction and the Z-axis direction may be larger on the tip portion 13c side than on the bottom surface 30a side. In this case, by narrowing the groove portion 30 on the base material 8 side, the flow path resistance increases and the necessary constituent member is retained, and by widening the groove portion 30 on the tip portion side, it becomes easier to discharge the surplus constituent member.

[0047] The manufacturing method of the mounting substrate 1 according to the present embodiment is a manufacturing method of the mounting substrate 1 for manufacturing the mounting substrate 1 by mounting the electronic component 2 on the above-described circuit board 3. After arranging the constituent member 20 on the base material 8 and arranging the electronic component 2, the electronic component 2 may be joined to the terminal 10 using the pressure reflow device 49.

[0048] In this case, the same functions and effects as those of the above-described circuit board 3 can be obtained.

[0049] The present disclosure is not limited to the above-described embodiments. For example, the number and arrangement of the terminals of the circuit board are not particularly limited. Further, in the above-described embodiments, one electronic component 2 was arranged inside the inner wall 9, but a plurality of electronic components 2 may be arranged. The arrangement mode of the plurality of electronic components 2 is not particularly limited.

[0050] In the above-described embodiments, the groove portions 30 were formed in each of the wall frame portions 13A, 13B, 13C, and 13D. Instead of or in addition to this, the groove portions 30 may be formed at the corners of the inner wall 9. For example, the configuration shown in FIG. 11 may be adopted. In the example shown in FIG. 11, the groove portions 30 are formed at the four corners of the rectangular frame-shaped inner wall 9. A line connecting the corners of the virtual reference shapes T1 and T2 set for the inner wall 9 is defined as the reference line SL. At this time, the groove portion 30 may extend along the direction in which the reference line SL extends. Thereby, the groove portion 30 penetrates the inner wall 9 at the positions of the corners of the reference shape T1 on the inner peripheral side and the corners of the reference shape T2 on the outer peripheral side. Note that the groove portion 30 formed at the corner may also have a recessed portion 45 as shown in FIG. 5.

[0051] The structure of the outer wall 40 is not particularly limited, and the structure shown in FIG. 12 may be adopted. In the example shown in FIG. 12, instead of the outer wall 40 having a frame-like shape, it has a pattern formed of a continuous insulating material (substantially uniformly formed) covering the main surface 8a of the base material 8. The pattern is a pattern formed by coating the main surface 8a of the base material 8 with the insulating material in a continuous state. In the following description, such a pattern may be referred to as a continuous pattern, and the film formed with such a pattern may be referred to as a continuous film. The outer wall 40 of the continuous pattern extends to the outer wall 40 with respect to the adjacent cavity 11, for example, as shown in FIG. 15(c), and has an integrated shape. That is, there is no break in the outer wall 40 between the cavity 11 and the adjacent cavity 11. Not limited to the periphery of the cavity 11, when the surface of the base material 8 is covered over a wide range, the surface of the base material 8 can be protected by the outer wall 40. When the region between the cavity 11 and the cavity 11 is covered by the outer wall 40 without a gap, the surface of the base material 8 in the region can be protected by the outer wall 40. The vicinity of the edge of the base material 8 may or may not be covered by the outer wall 40.

[0052] Here, when the outer wall 40 is constituted by a continuous film such as a wide film, as shown in FIG. 13, the end portion 41d on the base material 8 side in the height direction on the inner peripheral surface 41a of the outer wall 40 may be disposed on the inner peripheral side rather than the tip portion 41c. In FIG. 13, the position PG2 of the end portion 41d on the base material 8 side on the inner peripheral surface 41a is disposed on the inner peripheral side rather than the position PG1 of the tip portion 41c. At this time, on the outer peripheral surface 13b of the inner wall 9, the end portion 13d on the base material 8 side is disposed on the outer peripheral side rather than the tip portion 13c.

[0053] As shown in FIGS. 14 and 15, various variations may be adopted as the structure of the outer wall 40. As shown in FIG. 14(a), a plurality of inner walls 9 may be provided inside the outer wall 40. That is, the outer wall 40 may collectively surround the cavities 11 of the plurality of inner walls 9. Specifically, a plurality (three) of inner walls 9 are arranged in parallel between the wall frame portion 41C and the wall frame portion 41D. The wall frame portion 41A and the wall frame portion 41B collectively sandwich a plurality of inner walls 9 arranged in series in the facing direction.

[0054] In FIG. 14(a), when viewed from the height direction, let the area of the cavity 11 inside each inner wall 9 be SA1, and let the total area between the plurality of n inner walls 9 and the outer wall 40 be SA2. The area SA1 is the area of the reference shape T1 on the inner peripheral side with respect to the inner wall 9. SA2 is a value obtained by subtracting the total of the areas of n reference shapes T2 on the outer peripheral side of the inner wall 9 from the area of the rectangle formed by the inner peripheral surface 41a of the outer wall 40. In FIG. 14(a), since three inner walls 9 are provided, “n = 3”. At this time, the following equations (1) and (2) may hold. In this case, the outer wall 40 can collectively receive the structural members 20 discharged from the plurality of inner walls 9. Also, the space between the outer wall 40 and the plurality of inner walls 9 can secure the volume necessary to receive the discharged structural members 20. SA2≧(n×SA1) / 3 …(1) SA2≦ n×SA1 …(2)

[0055] As shown in FIG. 14(b), an outer wall 40B formed by a continuous film and a frame-shaped outer wall 40A may be combined. In FIG. 14(b), two inner walls 9 are surrounded by the outer wall 40A of the continuous film, and one inner wall 9 is surrounded by the frame-shaped outer wall 40B. The outer wall 40A of the continuous film has an outer wall 40Aa for one inner wall 9 and an outer wall 40Ab for the other inner wall 9 connected to each other. Thereby, the outer wall 40A is configured as one film pattern including a plurality of outer walls 40Aa and 40Ab.

[0056] In FIG. 14, a configuration in which the inner walls 9 arranged in a row are surrounded by the outer wall 40 is illustrated. As shown in FIG. 15, the inner walls 9 arranged in a plurality of rows may be surrounded by the outer wall 40. The number of inner walls 9 per row and the number of rows are not limited, but here, two rows of inner walls 9 arranged in three are provided. In the example shown in FIG. 15(a), the inner walls 9 in a plurality of rows are collectively surrounded by one outer wall 40.

[0057] In the example shown in FIG. 15(b), the inner wall 9 for one row is surrounded by the outer wall 40C of a continuous film, and the inner wall 9 for another row is surrounded by the outer wall 40D of a continuous film. The outer wall 40C is configured as a pattern of a continuous film including a plurality of outer walls 40Ca, 40Cb, 40Cc. The outer wall 40D is configured as a pattern of a continuous film including a plurality of outer walls 40Da, 40Db, 40Dc. In the example shown in FIG. 15(c), the inner walls 9 for two rows are surrounded by the outer wall 40E of a continuous film. The outer wall 40E is configured as a pattern of a continuous film including a plurality of outer walls 40Ea, 4Eb, 40Ec, 40Ed, 40Ee, 40Ef.

[0058] In the above-described embodiments and modifications, the outer wall 40 did not contact the inner wall 9. However, within the scope where the effects of the present invention can be obtained, the outer wall 40 may be in contact with the inner wall 9 in part. In this case, the outer wall 40 can support the inner wall 9 that receives pressure. For example, the structures shown in FIGS. 16 and 17 may be adopted. Note that FIGS. 16 and 17 illustrate a configuration in which one outer wall 40 surrounds one inner wall 9, but these structures may be adopted for the structures shown in FIGS. 14 and 15 and the like.

[0059] At least one of the four wall frame portions 41 of the outer wall 40 may contact and support the wall frame portion 13 of the inner wall 9. In the example shown in FIG. 16(a), the wall frame portion 41B supports the wall frame portion 13B. In this configuration, a structure is formed in which no space SP is formed between the wall frame portion 41B and the wall frame portion 13B. In this state, the outer wall 40 surrounds the cavity 11 while being in contact with the inner wall 9 in part. In this case, outside the wall frame portion 13B, the contamination range of the base material 8 by the structural material 20 can be narrowed. In the example shown in FIG. 16(b), the wall frame portion 41B is in contact with the wall frame portion 13B via the spacer 49. In this configuration, a space SP is formed between the wall frame portion 41B and the wall frame portion 13B. In the example shown in FIG. 16(c), the width of the wall frame portion 13B supported by the spacer 49 is reduced according to the shape of the spacer 49. Therefore, the widths of the groove portions 30 on both sides of the wall frame portion 13B are increased.

[0060] As shown in FIG. 17, among the four-sided wall frame portions 41, a plurality of the wall frame portions 41 may contact the wall frame portions 13 of the inner wall 9. In the example shown in FIG. 17(a), the wall frame portions 41A and 41B in two directions support the wall frame portions 13A and 13B. In this configuration, a structure is formed in which spaces SP are formed at two locations between the wall frame portions 41C, 41D and the wall frame portions 13C, 13D. In this state, the outer wall 40 surrounds the cavity 11 while contacting the inner wall 9 in two directions. In the example shown in FIG. 17(b), the wall frame portions 41A, 41B, and 41C in three directions support the wall frame portions 13A, 13B, and 13C. In this configuration, a structure is formed in which a space SP is formed at one location between the wall frame portion 41D and the wall frame portion 13D. In this state, the outer wall 40 surrounds the cavity 11 while contacting the inner wall 9 in three directions. In the example shown in FIG. 17(c), the four-sided wall frame portions 41A, 41B, 41C, and 41D are in contact with the wall frame portions 13A, 13B, 13C, and 13D via the spacers 49. In this configuration, a space SP is formed between the four-sided wall frame portion 41 and the wall frame portion 13. In the example shown in FIG. 17d(c), the widths of the wall frame portions 13A, 13B, 13C, and 13D supported by the spacer 49 are reduced according to the shape of the spacer 49.

[0061] [Embodiment] An embodiment of the mounting substrate according to the present disclosure will be described. Note that the present disclosure is not limited to the following embodiments.

[0062] First, the mounting substrates of Examples 1 to 7 were fabricated by the following manufacturing method. First, an inner wall 9 having a groove portion 30 and an outer wall 40 were formed on a base material 8 so as to surround a terminal 10 and a bonding material 4, thereby obtaining a circuit board 3. Next, the circuit board 3 was filled with a structural material 20 and an LED chip was mounted as an electronic component 2. Next, the mounting substrate 1 in this state was pressurized at 0.01 MPa with a pressure reflow device 49 and reflowed at 150°C to 190°C. As a result, the circuit board 3 and the electronic component 2 were joined. The various conditions of Examples 1 to 7 are shown in the tables of FIGS. 18 to 19. In the table of FIG. 18, the "inner wall (inner) opening width W1" is the dimension in the longitudinal direction of the reference shape T1 on the inner peripheral side of the inner wall 9 (see FIG. 3). The "inner wall (inner) opening width L1" is the dimension in the short transverse direction of the reference shape T1 on the inner peripheral side of the inner wall 9 (see FIG. 3). The "inner wall frame width bottom" is the thickness Ti at the position of the base material 8 of the wall frame portion 13 of the inner wall 9 (see FIG. 2). The "inner wall (outer) opening width W2" is the dimension in the longitudinal direction of the reference shape T2 on the outer peripheral side of the inner wall 9 (see FIG. 3). The "inner wall (outer) opening width L2" is the dimension in the short transverse direction of the reference shape T2 on the outer peripheral side of the inner wall 9. (See FIG. 3). The "inner wall height" is the height Hi of the inner wall 9 (see FIG. 2). The "groove opening position" indicates the position of the groove portion 30. "Up, down, left, and right" means that the groove portion 30 is at the center position of each of the wall frame portions 13A, 13B, 13C, and 13D, and "square" means that the groove portion 30 is at the corner position where the wall frame portions 13A, 13B, 13C, and 13D intersect. The "groove opening Top width" is the dimension of the width of the groove portion 30 at the tip portion 13c. In the table of FIG. 19, the "resist opening Bottom" means the bottom width of the groove portion 30. The "margin" indicates the distance between the inner wall 9 and the outer wall 40. The "outer wall (inner) opening width W1" is the dimension in the longitudinal direction of the rectangle drawn by the inner peripheral surface 41a of the outer wall 40 (see FIG. 3). The "outer wall (inner) opening width L1" is the dimension in the short transverse direction of the rectangle drawn by the inner peripheral surface 41a of the outer wall 40 (see FIG. 3). The "outer wall frame width bottom" is the thickness To at the position of the base material 8 of the wall frame portion 41 of the outer wall 40 (see FIG. 2). Note that the examples (other than Example 7) in which dimensions are described have the configuration of FIG. 11. Examples 3 and 6 described as "solid film" have the configuration of FIG. 12 having a continuous film. The "outer wall height" is the height Ho of the outer wall 40 (see FIG. 2)."Inner wall and outer wall joint" indicates whether there is a location where the outer wall 40 is joined to the inner wall 9. Example 7 has the configuration shown in Fig. 17(a).

[0063] Fig. 20 shows the evaluation results of Examples 1 to 7. The evaluations shown in Fig. 20 indicate the evaluation results when circuit boards 3 of the number of samples described in "Mounting number" are created and electronic components 2 are mounted on those circuit boards 3. "Constituent material outer wall outflow" in the table of Fig. 20 indicates the result of whether there is a sample in which the constituent material 20 has flowed out to the outer wall 40. In any of Examples 1 to 7, there was no outflow. "NG in electronic component mounting" indicates the result of whether there are NG products in which the electronic component 2 could not be mounted on the circuit board 3. In any of Examples 1 to 7, there were no NG products. "Electronic component mounting rate" indicates the ratio of samples on which the electronic component 2 could be mounted on the circuit board 3. In any of Examples 1 to 7, the mounting rate was 100%. "OK" indicates the number of samples for which all of the evaluation results were OK. In any of Examples 1 to 7, all 28 were OK products. Note that "Inner wall inner volume" shown in Fig. 20 indicates the volume S1 in the cavity 11. "Chip occupancy volume" indicates the volume S3 occupied by the electronic component 2 in the cavity 11. "Inner-outer wall inner volume" is the volume S2 of the space SP (see Fig. 3) between the inner wall 9 and the outer wall 40. Any of Examples 1 to 7 satisfies the conditions of "S2 ≤ S1" and "S2 ≥ S3".

[0064] [Form 1] A base material having a main surface, A first terminal and a second terminal provided on the main surface of the base material, An inner wall of an insulating material provided on the main surface of the base material, a circuit board comprising: The first and second terminals are arranged in a cavity surrounded by the inner wall, The inner wall has at least one groove portion penetrating from the inner peripheral surface to the outer peripheral surface, On the outer peripheral side of the inner wall, an outer wall of an insulating material is provided on the main surface of the base material so as to surround the cavity. A circuit board. [Form 2] The circuit board according to Form 1, wherein the height of the inner wall is equal to or greater than the height of the outer wall. [Form 3] The circuit board according to Form 1 or 2, wherein when the volume of the space between the inner wall and the outer wall is S2 and the volume occupied by the electronic components mounted in the cavity is S3, S2 is equal to or greater than S3. [Form 4] Any surface of at least one of the inner wall and the outer wall that extends in a first direction perpendicular to the main surface of the base material has a recess at a position on the base material side in the first direction. The circuit board according to any one of Forms 1 to 3, wherein a cavity material covering the substrate is provided at the position of the recess. [Form 5] The circuit board according to any one of Forms 1 to 4, wherein an end portion on the base material side of the inner peripheral surface of the outer wall in a first direction perpendicular to the main surface of the base material is disposed on the inner peripheral side rather than the tip portion. [Form 6] When the thickness at the tip portion of the wall frame portion of the outer wall in a first direction perpendicular to the main surface of the base material is Tto, the thickness at the end portion on the base material side is Tbo, and the height of the wall frame portion of the outer wall is Ho. The circuit board according to any one of Forms 1 to 5, wherein a taper shape condition is satisfied such that Tbo is equal to or greater than Tto and equal to or greater than Ho. [Form 7] A plurality of n inner walls are provided in the outer wall. When the area within each inner wall is SA1 as viewed from a first direction perpendicular to the main surface of the base material, and the total area between the plurality of inner walls and the outer wall is SA2, the following formulas (1) and (2) are satisfied. The circuit board according to any one of Forms 1 to 6. SA2 ≧ (n × SA1) / 3 …(1) SA2 ≦ n × SA1 …(2) [Form 8] The circuit board according to any one of Forms 1 to 7, wherein the outer wall is in contact with the inner wall at least in part. [Form 9] When viewed from the thickness direction of the wall frame portion of the inner wall, the groove portion extends from the tip portion of the wall frame portion of the base material toward the base material side in a first direction orthogonal to the main surface of the base material. The circuit board according to any one of Forms 1 to 8, wherein the width of the groove portion in the width direction orthogonal to the thickness direction and the first direction is larger on the tip portion side than on the bottom surface side. [Form 10] A method for manufacturing a mounting substrate, which manufactures a mounting substrate by mounting electronic components on the circuit board according to any one of Forms 1 to 9, A method for manufacturing a mounting substrate, wherein a constituent material is arranged on the base material, the electronic component is arranged, and then the electronic component is joined to the terminal using a pressure reflow device.

Explanation of Signs

[0065] 1... Mounting substrate, 2... Electronic component, 3... Circuit board, 4A... Bonding material, 8... Base material, 9... Inner wall, 10... Terminals (first terminal, second terminal), 11... Cavity, 20... Constituent material, 30... Groove portion, 40... Outer wall, 41... Wall frame portion, 41c... Tip portion, 41d... End portion, 49... Pressure reflow device.

Claims

1. A base material having a main surface, a first terminal and a second terminal provided on the main surface of the base material, and an inner wall of an insulating material provided on the main surface of the base material, a circuit board comprising: the first and second terminals are disposed within a cavity surrounded by the inner wall, the inner wall has at least one groove portion penetrating from an inner peripheral surface to an outer peripheral surface, on an outer peripheral side of the inner wall, an outer wall of an insulating material is provided on the main surface of the base material so as to surround the cavity, a circuit board.

2. The circuit board according to claim 1, wherein a height of the inner wall is equal to or greater than a height of the outer wall.

3. The circuit board according to claim 1, wherein when a volume of a space between the inner wall and the outer wall is S2 and a volume occupied by an electronic component mounted in the cavity is S3, S2 is equal to or greater than S3.

4. Any of surfaces extending in a first direction orthogonal to the main surface of the base material of at least one of the inner wall and the outer wall has a recess at a position on the base material side in the first direction, The circuit board according to claim 1, wherein a cavity material covering the substrate is provided at a position of the recess.

5. The circuit board according to claim 1, wherein an end portion on the base material side in a first direction orthogonal to the main surface of the base material of an inner peripheral surface of the outer wall is disposed on an inner peripheral side rather than a tip portion.

6. When a thickness at a tip portion in a first direction orthogonal to the main surface of the base material of a wall frame portion of the outer wall is Tto, a thickness at an end portion on the base material side is Tbo, and a height of the wall frame portion of the outer wall is Ho, The circuit board according to claim 1, wherein a taper shape condition is satisfied in which Tbo is equal to or greater than Tto and equal to or greater than Ho.

7. A plurality of n inner walls are provided within the outer wall, When, as viewed from a first direction orthogonal to the main surface of the base material, an area within each inner wall is SA1 and a total area between the plurality of inner walls and the outer wall is SA2, the following formulas (1) and (2) are satisfied, the circuit board according to claim 1. SA2 ≧ (n × SA1) / 3 …(1) SA2 ≦ n × SA1 …(2)

8. The circuit board according to claim 1, wherein the outer wall is in contact with the inner wall in part.

9. As viewed from a thickness direction of a wall frame portion of the inner wall, the groove portion extends from a tip portion of the wall frame portion in a first direction orthogonal to the main surface of the base material toward the base material side, The circuit board according to claim 1, wherein the width of the groove portion in the width direction orthogonal to the thickness direction and the first direction is larger on the tip end side than on the bottom surface side.

10. A method for manufacturing a mounting substrate by mounting electronic components on the circuit board according to any one of claims 1 to 9, A method for manufacturing a mounting substrate, comprising arranging a constituent material on the base material, arranging the electronic components, and then joining the electronic components to the terminals using a pressure reflow device.

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