Circuit board, and method for manufacturing mounting board

Abstract

To provide a circuit board that can prevent faulty connection between the circuit board and an electronic part, and can improve the accuracy of the position of the mounted electronic part, and a method for manufacturing a mounting board.SOLUTION: A cavity 11 in a wall 9 can be used for a mechanism for locating an electronic part 2. When an inner peripheral surface 13a of a wall frame part 13 has a large groove part, strain may occur in the inner peripheral surface 13a. Meanwhile, a groove part 30 is formed in at least one of corner parts 14 formed by two wall frame parts 13 of the wall 9. In this case, the wall frame part 13 has not groove part 30 (or even if the wall frame part has the groove part, it can reduce the size of the groove part), and thus strain in the inner peripheral surface 13a can be prevented. Consequently, the electronic part 2 can be accurately located by using the inner peripheral surface 13a of the wall frame part 13.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, such as 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, Patent Document 2 has also developed a technology 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.

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 structural 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 to be bonded to the circuit board, thereby mounting the electronic component. At this time, due to surplus structural 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 pressurizing 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. In addition, it is required to improve the positional accuracy of the electronic component to be mounted on the circuit board.

[0005] An object of the present disclosure is to provide a circuit board capable of suppressing a connection failure between a circuit board and an electronic component and improving the positional accuracy of the mounted electronic component, and a method for manufacturing a mounting board.

Means for Solving the Problems

[0006] The circuit board according to the present disclosure is a circuit board including a base material having a main surface, a first terminal and a second terminal provided on the main surface of the base material, and one or more insulating material walls provided on the main surface of the base material, wherein the first and second terminals are disposed in a cavity surrounded by the walls, and at least one of the corner portions formed from two wall frame portions of the walls has a groove portion penetrating from the inner peripheral surface to the outer peripheral surface.

[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 structural material is disposed on the base material, the electronic component is disposed, and then the electronic component is bonded to the terminal using a pressure reflow device.

Effects of the Invention

[0008] According to the present disclosure, it is possible to provide a circuit board capable of suppressing a connection failure between a circuit board and an electronic component and improving the positional accuracy of the mounted electronic component, and a method for manufacturing a mounting board.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Embodiments 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 board 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 board 1 includes an electronic component 2 and a circuit board 3. The mounting board 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 constituted by, 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, a wall 9, 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 (the second direction) is a direction parallel to the main surface 8a of the base material 8, the Y-axis direction (the 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 (the first direction, the height direction) is a direction orthogonal to the main surface 8a of the base material 8.

[0014] The insulating wall 9 is provided on the main surface 8a of the base material 8. The wall 9 is a member formed of an insulating material. The 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 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 parallel to 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 parallel to 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, the wall 9 has a rectangular frame-like structure when viewed from the height direction. 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 dimensions of the wall frame portions 13A and 13B in the Y-axis direction may be set to 10 μm to 60 μm. The dimensions 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 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 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 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 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 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 wall 9.

[0015] 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, a film such as Ti, Cu, Ni, Al, Mo, Cr, Ag, or a film in which metal particles and a binder are mixed is adopted.

[0016] 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. 12). 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. In addition to Sn, the bonding material 4 may be composed of an alloy containing an element that lowers the melting point of 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 brittle intermetallic compounds exist, they are likely to break due to external stress, so the reliability is likely to decrease. Therefore, by surrounding the electronic component 2 with the wall 9, the effect of protecting the electronic component 2 appears.

[0017] A cavity 11 is formed in the wall 9. The cavity 11 is constituted by a through hole that penetrates the 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 wall 9, and thus are surrounded by the wall 9 on the periphery. 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-sided wall frame portions 13A, 13B, 13C, 13D constituting the cavity 11.

[0018] In the cavity 11, a structural member 20 is arranged between the electronic component 2 and the bonding material 4 and the wall 9. As a result, by being supported by the structural member 20, the electronic component 2 can be made difficult to be peeled off from the circuit board 3. In addition, the force applied to the electronic component 2, the bonding material 4, and the terminals 7, 10 can be relaxed, and the reliability can be improved. As the material of the structural member 20, for example, epoxy resin, acrylic resin, phenol 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.

[0019] 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 arranged on the upper side of the terminal 10 (the upper surface of the conductive film 12). The circuit board 3 includes a bonding material 4A (first bonding material) on the side in the X-axis direction arranged on the terminal 10A and a bonding material 4A (second bonding material) on the negative side in the X-axis direction arranged on the terminal 10B. 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 arranged in the wall 9 formed of an insulator.

[0020] As shown in FIG. 3, the rectangular frame-shaped wall 9 has wall frame portions 13A, 13B, 13C, and 13D provided on four sides, and thus has four corner portions 14A, 14B, 14C, and 14D. The corner portion 14A is formed from the wall frame portions 13A and 13C. The corner portion 14B is formed from the wall frame portions 13B and 13C. The corner portion 14C is formed from the wall frame portions 13A and 13D. The corner portion 14D is formed from the wall frame portions 13B and 13D. At least one of the corner portions 14A, 14B, 14C, and 14D has at least one groove portion 30 that penetrates from the inner peripheral surface 13a to the outer peripheral surface 13b.

[0021] When viewed from the height direction (the first direction), a rectangular reference shape T1 with the minimum area circumscribing the inner peripheral surface 13a of the cavity 11 of the wall 9 is set. When viewed from the height direction, a rectangular reference shape T2 with the maximum area inscribed in the outer peripheral surface 13b of the 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. A line connecting the corners of the virtual reference shapes T1 and T2 is defined as a reference line SL. In the present embodiment, the groove portion 30 may extend along the direction in which the reference line SL extends. The groove portion 30 extends along the extending direction LD. In the present embodiment, the direction in which the reference line SL extends and the extending direction LD are parallel, but they do not have to be parallel. The definition of the extending direction LD will be described later. For example, in the example shown in FIG. 3, the groove portion 30 includes both the corners of the reference shape T1 and the corners of the reference shape T2, but the groove portion 30 may have a shape that does not include the corners of the reference shape T2. For example, as a strength measure, by moving the outer peripheral side end of the groove portion 30 toward the long side wall frame portions 13C and 13D, the groove portion 30 may have a shape that does not include the corners of the reference shape T2. In the following description, the direction in which the reference line SL extends when viewed from the height direction may be referred to as the "extending direction LD" in which the groove portion 30 extends. Also, the direction orthogonal to the extending direction LD and the height direction (Z-axis direction) may be referred to as the width direction WD of the groove portion 30. In FIG. 3, the extending direction LD and the width direction WD with respect to the corner 14D are shown, but the same-direction concepts are defined for the other corners 14. The groove portion 30 penetrates the wall 9 so as to include the positions of the corners of the inner peripheral reference shape T1 and the positions of the corners of the outer peripheral reference shape T2. Note that the groove portion 30 only needs to include at least one of the corners of the reference shape T1 and the corners of the reference shape T2 when viewed from the height direction. Therefore, the groove portion 30 does not have to include both of the reference shapes T1 and T2.

[0022] Note that at least one of the corners 14A, 14B, 14C, and 14D may have the groove portion 30. For example, as shown in FIG. 4(a), one of the four corners 14A, 14B, 14C, and 14D may have the groove portion 30. In the figure, the corner 14D has the groove portion 30, but the other corners may have the groove portion 30.

[0023] Further, at least a pair of diagonal corners may have the groove portion 30. By providing depressions in a pair of diagonal corners 14, the excess structural material 20 can be evenly flowed into the groove portion 30. The pair of diagonal corners 14 are the combination of corners 14A and 14D and the combination of corners 14B and 14C. In the figure, the combination of corners 14A and 14D has the groove portion 30, but the combination of corners 14B and 14C may have the groove portion 30.

[0024] Among the corners 14, at least one of the corners 14 without the groove portion 30 may have a recess 40 that is recessed to the outer peripheral side from the inner peripheral surface 13a. When viewed from the height direction (Z-axis direction in this embodiment), the recess 40 has a shape that is recessed to the outer peripheral side on the inner peripheral surface 13a of the cavity 11 of the wall 9. The recess 40 extends from the inner peripheral surface 13a toward the outer peripheral surface 13b side, but does not penetrate to the outer peripheral surface 13b. In the figure, all of the corners 14 where the groove portion 30 is not formed have the recess 40, but some of the corners 14 may have the recess 40.

[0025] Next, with reference to FIG. 5, the configuration when the groove portion 30 is viewed from the extending direction LD (also refer to FIG. 3) will be described. FIG. 5(a) is a view of the corner 14D between the wall frame portion 13B and the wall frame portion 13D viewed from the extending direction LD. Although the corner 14D is shown in FIG. 5, the same description applies to the other corners 14A, 14B, and 14C. As shown in FIG. 5(a), when viewed from the extending direction LD, the groove portion 30 extends from the tip portion 13c in the height direction (Z-axis direction in this embodiment) of the wall frame portions 13B and 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 of the bottom surface 30a to the tip portion 13c. In the example shown in FIG. 5(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 wall frame portion 13B and the wall frame portion 13D are separated by the groove portion 30.

[0026] As shown in FIG. 5(b), the width of the groove portion 30 in the width direction WD 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. 5(b), the groove portion 30 opens widely in the width direction WD 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.

[0027] As shown in FIG. 5(c), the bottom surface 30a of the groove portion 30 may be disposed at a position separated from the base material 8. Between the bottom surface 30a and the main surface 8a of the base material 8, there are members of the wall frame portions 13B and 13D.

[0028] As shown in FIG. 6, the edge portions of the groove portion 30 are rounded (corner R). As shown in FIG. 6(a), the edge portion 31 between the tip portion 13c and the side surface 30b is rounded. The edge portion 32 between the bottom surface 30a and the side surface 30b is rounded. As shown in FIG. 6(b), the edge portion 33 between the inner peripheral surface 13a and the side surface 30b is rounded. The edge portion 34 between the outer peripheral surface 13b and the side surface 30b is rounded.

[0029] As shown in FIGS. 7(a) and 7(b), when viewed from the height direction, the width of the groove portion 30 in the extending direction LD of the groove portion 30 and the width direction WD orthogonal to the height direction may be larger on one of the outer peripheral side and the inner peripheral side than on the other. For example, in the example shown in FIG. 7(a), the groove portion 30 increases in width as it goes from the inner peripheral side to the outer peripheral side. The separation distance in the width direction WD between the side surfaces 30b on both sides increases as it goes toward the outer peripheral side. In this case, the width of the groove portion 30 is larger on the outer peripheral side than on the inner peripheral side. In the example shown in FIG. 7(b), the groove portion 30 increases in width as it goes from the outer peripheral side to the inner peripheral side. The separation distance in the width direction WD between the side surfaces 30b on both sides increases as it goes toward the inner peripheral side. In this case, the width of the groove portion 30 is larger on the inner peripheral side than on the outer peripheral side.

[0030] As shown in FIG. 7(c), when looking from the height direction, among the widths of the groove portion 30 in the extending direction LD and the width direction WD orthogonal to the height direction, if the inner peripheral side width is W1, the width at the intermediate position in the extending direction LD is W2, and the outer peripheral side width is W3, either "W1, W3 ≧ W2, W3 ≧ W1" or "W1, W3 ≧ W2, W1 ≧ W3" may hold. W1 is the opening width on the inner peripheral surface 13a of the groove portion 30. W3 is the opening width on the outer peripheral surface 13b of the groove portion 30. W2 is the minimum width among the widths of the groove portion 30 in the extending direction LD between the inner peripheral surface 13a and the outer peripheral surface 13b. Further detailed description of the width of the groove portion 30 will be described later. The relationship "W1, W3 ≧ W2" means that the width at the intermediate position in the extending direction LD is less than or equal to the opening widths on the inner peripheral side and the outer peripheral side. Since the outer peripheral side opening width and the inner peripheral side opening width may be either larger or the same, "W3 ≧ W1" or "W1 ≧ W3" holds.

[0031] Next, with reference to FIGS. 3, 8, and 9, the size of the groove portion 30 will be described in more detail. Referring to FIG. 3, when looking from the thickness direction of the wall frame portions 13A, 13B, 13C, and 13D within the wall 9, let the total area of the inner peripheral surfaces 13a of the wall frame portions 13A, 13B, 13C, and 13D be S. The wall frame portions 13A and 13B have the X-axis direction as the thickness direction. The width of the wall frame portions 13A and 13B when looking from the thickness direction is the length of the short side of the reference shape T1, denoted as Li. The wall frame portions 13C and 13D have the Y-axis direction as the thickness direction. The width of the wall frame portions 13C and 13D when looking from the thickness direction is the length of the long side of the reference shape T1, denoted as Wi. Let the height of the wall 9 be H (see FIG. 8). At this time, the area S is obtained by multiplying the sum of the widths of the wall frame portions 13A, 13B, 13C, and 13D by the height H of the wall 9. That is, it is obtained by the following formula (3). Let the outer peripheral side widths of the wall 9 be Wo and Lo. S = (Wi + Wi + Li + Li) × H…(3)

[0032] Next, with reference to FIGS. 8 and 9, the dimensions of the groove portion 30 will be described. Here, as shown in FIG. 7(c), an example in which the width is the smallest at the mid-position in the extending direction LD will be described. When the structural member 20 passes through the groove portion 30, since the influence of the narrowest portion when viewed from the extending direction LD becomes large, the influence of the portion corresponding to the width W2 (see FIG. 7(c)) becomes large. As shown in FIG. 8, among the widths of the bottom surface 30a of the groove portion 30 in the width direction WD, the width corresponding to the mid-position width W2 is defined as W2b, the width corresponding to the width W1 of the inner peripheral side opening is defined as W1b, and the width corresponding to the outer peripheral side opening is defined as W3b. Among the widths of the tip portion 13c of the groove portion 30 in the width direction WD, the width corresponding to the mid-position width W2 is defined as W2t, the width corresponding to the width W1 of the inner peripheral side opening is defined as W1t, and the width corresponding to the outer peripheral side opening is defined as W3t. The length of the groove portion 30 in the extending direction LD on the bottom surface 30a of the groove portion 30 is defined as Lb (see FIG. 9).

[0033] Here, with reference to FIG. 9, the widths W1b, W2b, W3b, and the length Lb will be described in more detail. Each dimension is set based on the line of sight VL when looking at the groove portion 30 in the direction along the extending direction LD from the inside of the wall 9. Note that the same explanation also holds for the widths W1t, W2t, W3t, and the length Lt at the tip portion 13c. FIG. 9(a) illustrates a configuration in which the side surface 30b on the wall frame portion 13B side and the side surface 30b on the wall frame portion 13D side are symmetric with respect to the reference line SL. Among the side surfaces 30b on the wall frame portion 13B side, the points defining the respective widths W1b, W2b, W3b are denoted as P1B, P2B, P3B. Among the side surfaces 30b on the wall frame portion 13D side, the points defining the respective widths W1b, W2b, W3b are denoted as P1D, P2D, P3D. The extending direction LD is set as follows. First, a line segment connecting the midpoint P3M between the point P3B and the point P3D and the midpoint P1M between the point P1B and the point P1D when viewed from the height direction is defined as the line segment ML. At this time, the length of the line segment ML is defined as the "length Lb". Also, the direction parallel to the line segment ML is defined as the extending direction LD of the groove portion 30. The direction orthogonal to the line segment ML when viewed from the height direction is defined as the width direction WD. The distance between the straight line passing through the point P2B and parallel to the extending direction LD and the straight line passing through the point P2D and parallel to the extending direction LD is defined as the "width W2b". The distance between the straight line passing through the point P3B and parallel to the extending direction LD and the straight line passing through the point P3D and parallel to the extending direction LD is defined as the "width W3b". The distance between the straight line passing through the point P1B and parallel to the extending direction LD and the straight line passing through the point P1D and parallel to the extending direction LD is defined as the "width W1b".

[0034] In the form shown in FIG. 9, the line segments connecting points P1B and P1D, the line segments connecting points P2B and P2D, and the line segments connecting points P3B and P3D are all orthogonal to the reference line SL. Therefore, the separation distance between points P1B and P1D when viewed from the height direction is equal to the width W1b in the width direction WD. The separation distance between points P2B and P2D when viewed from the height direction is equal to the width W2b in the width direction WD. The separation distance between points P3B and P3D when viewed from the height direction is equal to the width W3b in the width direction WD. The length Lb of the groove portion 30 on the bottom surface 30a is set as the distance in the extending direction LD between points P1B, P1D and points P3B, P3D.

[0035] FIG. 9(b) illustrates a configuration in which the side surface 30b on the wall frame portion 13B side and the side surface 30b on the wall frame portion 13D side are asymmetric with respect to the reference line SL. Here, the side surface 30b on the wall frame portion 13D side is arranged at a position farther from the reference line SL than the side surface 30b on the wall frame portion 13B side. In this case, the line segments connecting points P1B and P1D, the line segments connecting points P2B and P2D, and the line segments connecting points P3B and P3D are not orthogonal to the reference line SL. Therefore, the separation distance between points P1B and P1D when viewed from the height direction is larger than the width W1b in the width direction WD. The separation distance between points P2B and P2D when viewed from the height direction is larger than the width W2b in the width direction WD. The separation distance between points P3B and P3D when viewed from the height direction is larger than the width W3b in the width direction WD. For the form of FIG. 9(b) as well, the line segment ML, the extending direction LD, and the width direction WD are set in the same procedure as described for FIG. 9(a), and the widths W1b, W2b, W3b, and the length Lb are set. Note that FIGS. 9(a) and 9(b) are merely examples of the shape of the side surface 30b, and various shapes can be adopted.

[0036] As shown in FIG. 8, when viewed from the extending direction LD of the groove portion 90 within the wall 9, let the opening area of the groove portion 30 be Sc. The opening area Sc is the portion indicated by hatching in FIG. 8. The opening area Sc is the area of the region surrounded by the side surface 30b, the bottom surface 30a, and a reference line STL which is a virtual line obtained by extending the tip portion 13c when viewed from the extending direction LD. The said opening area Sc is defined by a line segment drawn by the location which is arranged most inward in the width direction WD among the side surfaces 30b on both sides in the width direction WD. Let the depth of the groove portion 30 be Hs. The opening area Sc shown in FIG. 8 is obtained by the following formula (4). However, in the case of the configuration as shown in FIGS. 5(a) and 6(a), the calculation for obtaining the opening area Sc corresponding to each structure may be performed. Note that the lower limit value of the dimension of the width W2b corresponding to the minimum width of the groove portion 30 is not particularly limited, but may be, for example, 1 μm or more, and may be 4 μm or more. Regarding the upper limit value, it may be set within a range that satisfies the following formulas (1) and (2) described later. Also, when the bottom surface 30a is arranged at a position separated from the base material 8, the bottom surface 30a may be curved. Sc={(W2t + W2b)×Hs} / 2 …(4)

[0037] The following relationship of formula (1) holds between the area S of the wall frame portions 13A, 13B, 13C, 13D obtained as described above and the opening area Sc. Also, as described above, when the width of the bottom surface 30a of the groove portion 30 in the width direction WD is W2b and the length of the groove portion 30 in the extending direction LD on the bottom surface 30a of the groove portion 30 is Lb, the following formula (2) holds. Note that "n" in formula (2) means the total number of groove portions 30 that the wall 9 has. In the form shown in FIG. 3, since there are 4 groove portions 30, "n = 4". Also, for example, in the examples shown in FIGS. 7(a) and 7(b), among the openings on the inner peripheral side and the outer peripheral side, the dimension of the width of the narrower one is "W2b". 0.004≦Sc / S<0.6 …(1) 0.1≦Σ(W2bn / Lbn)<21.5 …(2)

[0038] Here, as shown in FIG. 10(a), any of the surfaces extending in the height direction of the wall 9 may have a recess 45 at a position on the substrate 8 side in the height direction, and a cavity material 46 covering the substrate 8 may be provided at the position of the recess 45. The surfaces extending in the height direction in the wall 9 are the inner peripheral surface 13a, the outer peripheral surface 13b, and the side surface 30b of the groove portion 30. Any of these surfaces 13a, 13b, 30b 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, and may be provided in a part thereof. The recess 45 is formed at a position closer to the substrate 8 than the tip portion 13c in the height direction. The recess 45 is formed at a position spaced upward from the main surface 8a of the substrate 8. Thus, the cavity material 46 is formed between the recess 45 and the main surface 8a of the substrate 8. The recess 45 may extend in the direction in which the surfaces 13a, 13b, 30b extend along the planar direction of the substrate 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 so as to extend in the Y-axis direction. Further, when the side surface 30b of the groove portion 30 at the corner portion 14D has the recess 45, the recess 45 may be formed so as to extend in the extending direction LD (see FIG. 3).

[0039] The opening width of the recess 45, that is, the size w1 of the dimension 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 size w2 of the dimension 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. 10(b), the recess 45 is formed at the position of the substrate 8, and the cavity material 46 is not formed. Since the bonding strength between the wall 9 and the substrate 8 is reduced in such a structure, the structure of FIG. 10(a) is more preferable. However, the structure as shown in FIG. 10(b) is not excluded.

[0040] Referring to FIGS. 11 and 12, a method for manufacturing a circuit board 3 and a mounting board 1 will be described. First, as shown in FIG. 11(a), terminals 10 are formed on the upper surface of a base material 8. Next, as shown in FIG. 11(b), a wall 9 is formed on the base material 8. Thereby, the circuit board 3 is completed. In FIG. 11(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. 11(c), a constituent member 20 is arranged on the base material 8 by filling the cavity 11 with the constituent member 20. Then, the electronic component 2 is held by a holding member and mounted in the cavity 11. Next, as shown in FIG. 12, 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 member 20. At this time, a part of the constituent member 20 is pushed out into the groove portion 30 (see FIG. 3). Next, by heating, the bonding material 4B of the electronic component 2 and the bonding material 4A of the base material 8 are bonded to each other. Thereby, the mounting board 1 is completed.

[0041] The circuit board 3 may include a bonding material 4A (first bonding material) containing a metal element, which is disposed on the terminal 10A, and a bonding material 4A (second bonding material) containing a metal element, which is 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] Next, referring to FIG. 13, a method for forming the wall 9 having the groove portion 30 will be described. First, as shown in FIG. 13(a), a wall 9 is formed on the base material 8. Next, as shown in FIG. 13(b), a part of the wall 9 is processed by irradiating the wall 9 with a laser using a laser device 51. Thereby, as shown in FIG. 13(c), a groove portion 30 is formed in the wall 9.

[0043] Alternatively, as shown in FIG. 13(d), a resist 52 is formed on the base material 8. Next, as shown in FIG. 13(e), exposure is performed using a glass mask 53 having a pattern corresponding to the shape of the wall 9 having the groove portion 30. As shown in FIG. 13(f), by developing the exposed resist 52, the wall 9 having the groove portion 30 is formed.

[0044] In addition, when forming an undercut portion (a recessed portion as shown in Fig. 10), the focus position of exposure may be shifted above the film surface. Alternatively, an undercut portion may be formed by overdevelopment. When the groove portion 30 does not reach the base material 8 as shown in Fig. 5(c) etc., the groove portion 30 may be formed by scraping only the surface of the wall 9 with a laser or the like.

[0045] Next, the operations and effects of the manufacturing method of the circuit board 3 and the mounting board 1 according to the present embodiment will be described.

[0046] First, with reference to Fig. 14, the circuit board 103 according to the comparative example will be described. The wall 9 of the circuit board 103 does not have the groove portion 30 described above. After filling the interior of the wall 9 with the structural material 20, when attempting to mount the electronic component 2 into the wall 9 using a holding member and push the electronic component 2 with a pressure reflow device, due to the influence of the excess structural material 20, the electronic component 2 cannot be pushed in sufficiently. In this case, reflow may be 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 was a possibility of connection failure between the bonding material 4A of the circuit board 3 and the electronic component 2.

[0047] In contrast, in the circuit board 3 according to the present embodiment, a pair of terminals 10 (a first terminal and a second terminal) are disposed in a cavity 11 surrounded by a wall 9. Here, the wall 9 has a 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 disposed in the cavity 11, an electronic component 2 is mounted using a holding member, and the electronic component 2 is pushed into the interior of the cavity 11 and heated using a pressure reflow device to be joined to the circuit board 3, thereby mounting the electronic component 2 on the circuit board 3, the surplus constituent member 20 can be discharged to the outside of the 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. Here, the cavity 11 in the wall 9 can be used as a mechanism for positioning the electronic component 2. When the inner peripheral surface 13a of the wall frame portion 13 has a large groove portion, there is a possibility that distortion occurs in the inner peripheral surface 13a. In contrast, at least one of the corner portions 14 formed by the two wall frame portions 13 of the wall 9 has a groove portion 30. In this case, since the wall frame portion 13 does not have (or can be made small even if it has) the groove portion 30, distortion of the inner peripheral surface 13a can be suppressed. Therefore, the electronic component 2 can be accurately positioned using the inner peripheral surface 13a of the wall frame portion 13. As described above, connection failure between the circuit board 3 and the electronic component 2 can be suppressed, and the positional accuracy of the mounted electronic component 2 can be improved.

[0048] The wall 9 has wall frame portions 13 provided on four sides, thereby having four corner portions 14. Among the four corner portions 14, at least a pair of diagonal corner portions 14 may have the groove portion 30, or the four corner portions 14 may have the groove portion 30. Since the corner portions 14 of the cavity 11 are the portions where the pressure of the constituent member 20 is most applied, by providing the groove portion 30 at the portion, it becomes easier to pour the surplus constituent member 20. Further, since at least a pair of diagonal corner portions 14 have the groove portion 30, the surplus constituent member 20 can be flowed out from the groove portion in a well-balanced manner.

[0049] When viewed from the extending direction of the groove portion 30, the groove portion 30 extends from the tip portion 13c in the Z-axis direction (the first direction) of the wall frame portion 13 toward the base material 8 side, and the bottom surface 30a of the groove portion 30 may be disposed at a position spaced apart from the base material 8. In this case, since the wall frame portions 13 constituting the corner portion 14 are connected on the base material 8 side, the strength of the wall 9 can be improved, and the positioning accuracy by the cavity 11 can be improved.

[0050] At least any one of the inner peripheral surface 13a, the outer peripheral surface 13b of the wall frame portion 13, and the side surface 30b of the groove portion 30 has a recessed portion 45 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 recessed portion 45. According to such a shape, the recessed portion 45 can function as a guide groove through which the constituent member 20 passes at a position on the base material 8 side. Therefore, the fluidity of the constituent member 20 can be improved.

[0051] Let the total area of the inner peripheral surface 13a of the wall frame portion 13 when viewed from the thickness direction of the wall frame portion 13 in the wall 9 be S, the opening area of the groove portion 30 when viewed from the extending direction LD of the groove portion 30 in the wall 9 be Sc, the width of the bottom surface 30a of the groove portion 30 in the width direction WD orthogonal to the extending direction LD and the Z-axis direction be W2b, and the length of the groove portion 30 in the extending direction LD on the bottom surface 30a of the groove portion 30 be Lb. In this case, the following formulas (1) and (2) may hold. By the establishment of formula (1), it is possible to suppress the constituent member 20 from becoming difficult to flow due to the ratio of the opening area being too small, and to suppress the necessary amount of the constituent member 20 from flowing out due to the ratio being too large. Further, by the establishment of formula (2), it is possible to suppress the constituent member 20 from becoming difficult to flow due to the width W2b becoming narrow and the pressure loss becoming large with respect to the length Lb which is the flow path length, and to suppress the necessary amount of the constituent member from flowing out due to the width W2b being too wide. 0.004 ≦ Sc / S < 0.6 …(1) 0.1 ≦ Σ(W2bn / Lbn) < 21.5 …(2)

[0052] When viewed from the thickness direction of the wall frame portion 13, the groove portion 30 extends from the tip end portion of the wall frame portion 13 in the first direction orthogonal to the main surface 8a of the base material 8 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 first direction may be larger on the tip end 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 to hold the necessary structural members, and by widening the groove portion 30 on the tip end portion side, it becomes easier to discharge the surplus structural members.

[0053] When viewed from the Z-axis direction, the width of the groove portion 30 in the extending direction LD of the groove portion 30 and the width direction WD orthogonal to the Z-axis direction may be larger on one of the outer peripheral side and the inner peripheral side than on the other. In this case, the fluidity of the structural member 20 flowing through the groove portion 30 from the inner peripheral side to the outer peripheral side can be controlled by the width of the groove portion 30. Further, thereby, the distortion of the wall 9 can be suppressed and the positioning accuracy by the cavity 11 can be improved.

[0054] When viewed from the Z-axis direction, among the widths of the groove portion 30 in the extending direction LD of the groove portion 30 and the width direction W orthogonal to the Z-axis direction, when the width on the inner peripheral side is W1, the width at the intermediate position in the extending direction is W2, and the width on the outer peripheral side is W3, one of "W1, W3 ≧ W2, W3 ≧ W1" or "W1, W3 ≧ W2, W1 ≧ W3" may be satisfied. In this case, the fluidity of the structural member 20 flowing through the groove portion 30 from the inner peripheral side to the outer peripheral side can be controlled by the widths at each position of the groove portion 30. Further, thereby, the distortion of the wall 9 can be suppressed and the positioning accuracy by the cavity 11 can be improved.

[0055] At least one of the corner portions 14 where the groove portion 30 is not formed among the corner portions 14 may have a concave portion 40 that is recessed toward the outer peripheral side from the inner peripheral surface. For example, as shown in FIG. 15(a), when the corner portion does not have the concave portion 40, before the electronic component 2 comes into contact with the inner peripheral surface, there is a possibility that the corner portion of the electronic component 2 and the corner portion in the cavity 11 interfere with each other. On the other hand, as shown in FIG. 15(b), since the corner portion 14 of the cavity 11 has the concave portion 40, it is possible to suppress the corner portion 14 of the cavity 11 from interfering with the corner portion of the electronic component 2.

[0056] The edge portion of the groove portion 30 may be rounded. In this case, it is possible to suppress the resistance received by the constituent material 20 during flow at the edge portion or the like.

[0057] The manufacturing method of the mounting substrate 1 according to the present embodiment is a manufacturing method of the mounting substrate 1 that manufactures the mounting substrate 1 by mounting the electronic component 2 on the above-described circuit board 3. After arranging the constituent material 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.

[0058] In this case, the same effects and advantages as those of the above-described circuit board 3 can be obtained.

[0059] 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 embodiment, one electronic component 2 was arranged in the 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.

[0060] [Examples] Examples of the mounting substrate according to the present disclosure will be described. Note that the present disclosure is not limited to the following examples.

[0061] First, mounting substrates of the comparative example and Examples 1 to 6 were fabricated by the following manufacturing method. First, a circuit board 3 was obtained by forming a wall 9 having a groove portion 30 at a corner so as to surround a terminal 10 and a bonding material 4 on a base material 8. Next, the circuit board 3 was filled with a constituent 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. Thereby, the circuit board 3 and the electronic component 2 were joined. The various conditions of the comparative example and Examples 1 to 6 are shown in the tables of FIGS. 16 to 18. In the table of FIG. 16, the "inner wall opening width Wi" is the dimension in the longitudinal direction of the reference shape T1 on the inner peripheral side of the wall 9 (see FIG. 3). The "inner wall opening width Li" is the dimension in the short transverse direction of the reference shape T1 on the inner peripheral side of the wall 9 (see FIG. 3). The "wall frame width Top: Ltw" is the thickness of the wall frame portions 13C and 13D on the long side of the wall 9. The "wall frame width Tip: Ltl" is the thickness of the wall frame portions 13A and 13B on the short side of the wall 9. The "outer wall opening width Wo" is the dimension in the longitudinal direction of the reference shape T2 on the outer peripheral side of the wall 9 (see FIG. 3). The "outer wall opening width Lo" is the dimension in the short transverse direction of the reference shape T2 on the outer peripheral side of the wall 9 (see FIG. 3). In the table of FIG. 17, the "groove position" indicates the position of the groove portion 30. "None" means that the groove portion 30 is not formed, "two corners" means that the groove portion 30 is formed at the corners 14A and 14D, "one corner" means that the groove portion 30 is formed at the corner 14D, and "four corners" means that the groove portion 30 is formed at the four corners 14. The "groove Top width: W2t" is the width on the tip portion 13c side of the groove portion 30 (see FIG. 8). The "groove Bottom: W2b" is the width on the bottom surface 30a side of the groove portion 30 (see FIG. 8). The "wall height: H" is the height of the wall 9 (see FIG. 8). The "groove depth: Hs" is the depth of the groove portion 30 (see FIG. 8). "S", "Sc", "Sc / S", and "ΣW2bn / Lbn" in the table of FIG. 18 correspond to the aforementioned formulas (1) and (2).

[0062] Figure 18 shows the evaluation results of the comparative example and Examples 1 to 6. The evaluation shown in Figure 18 indicates 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. "Wall peeling defect" in the table of Figure 18 shows the result of whether there is a sample in which the wall 9 peels off from the base material 8. In any of the comparative example and Examples 1 to 6, there was no peeling. "OK" indicates the number of samples in which the electronic component 2 could be mounted on the circuit board 3, and "electronic component mounting rate" indicates the ratio of OK products to the number of samples. In the comparative example, the electronic component mounting rate was as low as 10.7%, while in any of Examples 1 to 6, the mounting rate was 100%. Figure 21 shows the evaluation results of Examples 7 to 15.

[0063] [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, and one or more insulating material walls provided on the main surface of the base material, a circuit board comprising: the first and second terminals are disposed in a cavity surrounded by the wall, at least one of the corner portions formed from two wall frame portions of the wall has a groove portion penetrating from the inner peripheral surface to the outer peripheral surface, a circuit board. [Form 2] the wall has wall frame portions provided on four sides, thereby having four of the corner portions, among the four corner portions, at least a pair of the diagonally opposite corner portions have the groove portion, or the four corner portions have the groove portion, the circuit board according to Form 1. [Form 3] when viewed from the extending direction of the groove portion, the groove portion extends from the tip of the wall frame portion in a first direction orthogonal to the main surface of the base material toward the base material side, and the bottom surface of the groove portion is disposed at a position spaced apart from the base material, the circuit board according to Form 1 or 2. [Form 4] At least any one of the inner peripheral surface, outer peripheral surface, and side surface of the groove portion of the wall frame portion has a recessed portion at a position on the base material side in a first direction orthogonal to the main surface of the base material. A circuit board according to any one of Forms 1 to 3, wherein a cavity material covering the base material is provided at the position of the recessed portion. [Form 5] When the total area of the inner peripheral surface of the wall frame portion as viewed from the thickness direction of the wall frame portion in the wall is S, When the opening area of the groove portion as viewed from the extending direction of the groove portion in the wall is Sc, When the width of the bottom surface of the groove portion in the width direction orthogonal to the extending direction and the first direction orthogonal to the main surface of the base material is W2b, When the length of the groove portion in the extending direction on the bottom surface of the groove portion is Lb, A circuit board according to any one of Forms 1 to 4, wherein the following formulas (1) and (2) are satisfied. 0.004 ≦ Sc / S < 0.6 …(1) 0.1 ≦ Σ(W2bn / Lbn) < 21.5 …(2) [Form 6] When viewed from the thickness direction of the wall frame portion, the groove portion extends from the 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. A circuit board according to any one of Forms 1 to 5, wherein the width of the groove portion in the thickness direction and the width direction orthogonal to the first direction is larger on the tip portion side than on the bottom surface side. [Form 7] When viewed from a first direction orthogonal to the main surface of the base material, the width of the groove portion in the extending direction and the width direction orthogonal to the first direction is larger on one of the outer peripheral side and the inner peripheral side than on the other side. A circuit board according to any one of Forms 1 to 6. [Form 8] When viewed from a first direction perpendicular to the main surface of the base material, among the extending direction of the groove portion and the width of the groove portion in the width direction perpendicular to the first direction, the width on the inner peripheral side is designated as W1, the width at an intermediate position in the extending direction is designated as W2, and the width on the outer peripheral side is designated as W3, the circuit board according to any one of Forms 1 to 7, in which one of "W1, W3 ≥ W2, W3 ≥ W1" or "W1, W3 ≥ W2, W1 ≥ W3" is satisfied. [Form 9] Among the corner portions, at least one of the corner portions where the groove portion is not formed has a recess that is recessed to the outer peripheral side rather than the inner peripheral surface, the circuit board according to any one of Forms 1 to 8. [Form 10] The edge portion of the groove portion is rounded, the circuit board according to any one of Forms 1 to 9. [Form 11] A method for manufacturing a mounting substrate by mounting electronic components on the circuit board according to any one of Forms 1 to 10, A method for manufacturing a mounting substrate, in which a structural material is arranged on the base material, the electronic components are arranged, and then the electronic components are joined to the terminals using a pressure reflow device.

Explanation of Signs

[0064] 1... Mounting substrate, 2... Electronic component, 3... Circuit board, 4A... Bonding material, 8... Base material, 9... Wall, 10... Terminal, 11... Cavity, 13... Wall frame portion, 14... Corner portion, 20... Structural material, 30... Groove portion, 40... Recess, 45... Depression portion, 46... Cavity material, 49... Pressure reflow device.

Claims

1. A circuit board comprising a base material having a main surface, a first terminal and a second terminal provided on the main surface of the base material, and one or more insulating material walls provided on the main surface of the base material, wherein the first and second terminals are disposed within a cavity surrounded by the walls, at least one of the corners formed by two wall frame portions of the walls has a groove portion penetrating from an inner peripheral surface to an outer peripheral surface.

2. The wall has wall frame portions provided on four sides, thereby having four of the corners, among the four corners, at least a pair of the diagonal corners have the groove portion, or the four corners have the groove portion. The circuit board according to claim 1.

3. When viewed from the extending direction of the groove portion, the groove portion extends from the tip of the wall frame portion in a first direction perpendicular to the main surface of the base material toward the base material side, and the bottom surface of the groove portion is disposed at a position spaced apart from the base material. The circuit board according to claim 1.

4. At least any one of the inner peripheral surface, the outer peripheral surface, and the side surface of the groove portion of the wall frame portion has a recess at a position on the base material side in a first direction perpendicular to the main surface of the base material, and a cavity material covering the base material is provided at the position of the recess. The circuit board according to claim 1.

5. Let the sum of the areas of the inner peripheral surfaces of the wall frame portions when viewed from the thickness direction of the wall frame portions within the wall be S, let the opening area of the groove portion when viewed from the extending direction of the groove portion within the wall be Sc, let the width of the bottom surface of the groove portion in a width direction perpendicular to the extending direction and a first direction perpendicular to the main surface of the base material be W2b, and let the length of the groove portion in the extending direction on the bottom surface of the groove portion be Lb. In this case, the following formulas (1) and (2) hold. The circuit board according to claim 1. 0.004 ≦ Sc / S < 0.6 … (1) 0.1 ≦ Σ (W2bn / Lbn) < 21.5 … (2)

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

7. The circuit board according to claim 1, wherein, when viewed from a first direction orthogonal to the main surface of the base material, the width of the groove portion in the extending direction of the groove portion and the width direction orthogonal to the first direction is such that one of the outer peripheral side and the inner peripheral side is larger than the other.

8. The circuit board according to claim 1, wherein, when viewed from a first direction orthogonal to the main surface of the base material, among the widths of the groove portion in the extending direction of the groove portion and the width direction orthogonal to the first direction, the width of the inner peripheral side is defined as W1, the width at an intermediate position in the extending direction is defined as W2, and the width of the outer peripheral side is defined as W3, one of "W1, W3 ≥ W2, W3 ≥ W1" or "W1, W3 ≥ W2, W1 ≥ W3" is satisfied.

9. The circuit board according to claim 1, wherein at least one of the corner portions where the groove portion is not formed among the corner portions has a concave portion that is recessed to the outer peripheral side with respect to the inner peripheral surface.

10. The circuit board according to claim 1, wherein the edge portion of the groove portion is rounded.

11. A method for manufacturing a mounting substrate by mounting electronic components on the circuit board according to any one of claims 1 to 10, A method for manufacturing a mounting substrate, comprising arranging a structural 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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