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: On a circuit board 3, a pair of terminals 10 and a joint material 4A are arranged inside a wall 9. When seen from a Z-axis direction, the wall 9 has at least one hollow part 30 depressed toward an outer periphery in an inner peripheral surface 13a of a cavity 11. In this case, when a component 20 is arranged inside the wall 9, an electronic part is mounted by using a holding member, and the electronic part 2 is pushed into the wall 9 and heated by using a pressure reflow device 49 to be joined to the circuit board 3, thereby mounting the electronic part 2 on the circuit board 3, an excess component 20 can be discharged to the outside of the wall 9 through the hollow part 30. Consequently, the electronic part 2 can be sufficiently pushed into the wall 9 and brought into contact with the joint material 4A through a pressure step using the pressure reflow device 49.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, a technology 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 and display devices, on a wiring board has 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, 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 has 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 joining material may be disposed inside a 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 wall and heated using a pressure reflow device to be joined to the circuit board, thereby mounting the electronic component. At this time, due to the 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 between the joining material of the circuit board and the electronic component.

[0005] An object of the present disclosure is to provide a circuit board capable of suppressing a connection failure between a bonding material of a circuit board and an 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 a wall of an insulating material provided on the main surface of the base material. The first and second terminals are arranged in a cavity formed in the wall, and when viewed from a first direction orthogonal to the main surface of the base material, the wall has at least one recessed portion recessed toward the outer peripheral side on the inner peripheral surface of 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. After arranging a constituent material on the base material and arranging the electronic component, the electronic component may be joined 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 bonding material of a circuit board and an electronic component, and a method for manufacturing a mounting board.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

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Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

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Figure 17

Figure 18

Embodiments for Carrying Out the Invention

[0010] With reference 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 alloys 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, known resin materials and ceramic materials used for printed circuit boards may be adopted. In the following description, the explanation 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 spaced apart 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 spaced apart 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 on the positive side in the X-axis direction of the wall frame portions 13C and 13D. The wall frame portion 13B connects the ends on the negative side in the X-axis direction of the wall frame portions 13C and 13D. Thereby, when viewed from the Z-axis direction, the wall 9 has a rectangular frame-like structure. The wall frame portions 13A and 13B form the short sides, and the wall frame portions 13C and 13D form 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 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. The height dimension (dimension in the Z-axis direction) of the wall 9 rising from the base material 8 may be set to 5 μm to 10 μm. As the material of the wall 9, for example, resin materials such as epoxy resin, acrylic resin, phenol 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] Terminal 10 is a metal part provided on the main surface 8a of the base material 8. As the material of 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 terminal 10. As the material of 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 the bonding material 4A on the circuit board 3 side and the bonding material 4B on the electronic component 2 side to integrate them (see FIG. 6). 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 (IMC). 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 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. Thereby, on the bottom side of the cavity 11, the upper surface of the base material 8 is exposed. The cavity 11 is rectangular when viewed in 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 formed in the wall 9 and 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. Thereby, by supporting with 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 alleviated, and the reliability can be improved. As the material of the structural member 20, for example, an epoxy resin, an acrylic resin, a phenolic resin, a melamine resin, a urea resin, an alkyd resin, or a mixture thereof, or a mixture of the resin material and SiOx, ceramics, etc. is adopted. Particularly preferably, an epoxy resin or an acrylic resin is 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 wall frame portions 13A, 13B, 13C, and 13D of the wall 9 each have at least one recessed portion 30. The recessed portion 30 has a shape that is recessed toward the outer peripheral side on the inner peripheral surface 13a of the cavity 11 of the wall 9 when viewed from the height direction (Z-axis direction in this embodiment). The recessed portion 13 extends from the inner peripheral surface 13a toward the outer peripheral surface 13b side but does not penetrate to the outer peripheral surface 13b. As a result, the recessed portion 30 has an end face 30c on the outer peripheral side. For the wall frame portions 13A and 13B, the X-axis direction is the thickness direction. Therefore, the recessed portion 30 of the wall frame portions 13A and 13B extends in the X-axis direction and has an end face 30c on the outer peripheral side in the X-axis direction. For the wall frame portions 13C and 13D, the Y-axis direction is the thickness direction. Therefore, the recessed portion 30 of the wall frame portions 13C and 13D extends in the Y-axis direction and has an end face 30c on the outer peripheral side in the Y-axis direction. Note that the recessed 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 recessed portions 30 may be formed in the wall frame portions 13A, 13B, 13C, and 13D. Further, recessed 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).

[0021] Next, with reference to FIG. 4, the configuration when the wall frame portion 13D is viewed from the thickness direction will be described. FIG. 4 is a view of the wall frame portion 13D viewed from the Y-axis direction, which is the thickness direction. Although only the wall frame portion 13D is shown in FIG. 4, the same explanation also holds for 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 recessed portion 30 extends from the tip portion 13c in the height direction of the wall frame portion 13D toward the base material 8 side (negative side in the Z-axis direction). The recessed 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 relative to 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 recessed 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 recessed 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 inner peripheral surface of the wall frame portion 13D are separated by the recessed portion 30.

[0022] As shown in FIG. 4(b), the width of the recess 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 recess 30 at the tip portion 13c is larger than the width of the recess 30 at the bottom surface 30a. In the example shown in FIG. 4(b), the recess 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.

[0023] As shown in FIG. 4(c), the bottom surface 30a of the recess 30 may be disposed at a position separated from the base material 8. There is a member of the wall frame portion 13D between the bottom surface 30a and the main surface 8a of the base material 8.

[0024] Next, the size of the recess 30 will be described. As shown in FIG. 3, when viewed from the height direction, a rectangular reference shape T having the minimum area circumscribing the inner peripheral surface 13a of the cavity 11 of the wall 9 is set. In the present embodiment, the reference shape T has a rectangular shape (here, a rectangular shape). This reference shape T is virtually set and is shown by a virtual line in FIG. 3. Let the volume obtained by multiplying the height of the wall 9 (the height dimension H (dimension in the first direction) shown in FIG. 4(a)) by such a reference shape T be Vc. Let the volume of each recess 30 be Vn. For example, the volume Vn of the recess 30 of the wall frame portion 13A is calculated by multiplying the area of the rectangle hatched in FIG. 3 by the height of the wall 9 (the height dimension H shown in FIG. 4(a)). Let the volume of each bonding material 4A be Vp. At this time, the following formula (1) may hold. The left side of formula (1) indicates the total value of the volumes Vn of the recesses 30 existing in one cavity 11. In the example shown in FIG. 3, it is the total value of the four recesses 30 formed in each of the wall frame portions 13A, 13B, 13C, and 13D. ΣVn≦Vc - 2Vp …(1)

[0025] Let the length of the longitudinal side (the first side) of the rectangular reference shape T be L. Let the length of the short side (the second side) of the reference shape T be W. Let the maximum width of the opening width of the recess 30 on the longitudinal side be XL Let it be so. Here, the dimension in the X-axis direction of the opening of the recessed portion 30 of the wall frame portions 13C and 13D corresponds to the opening width. The maximum width of the opening width of the recessed portion 30 of the side in the short side direction is X W Let it be so. Here, the dimension in the Y-axis direction of the opening of the recessed portion 30 of the wall frame portions 13A and 13B corresponds to the opening width. At this time, equations (2) and (3) hold. In addition, in order to set the lower limits for equations (1) to (3), equations (4) to (6) may hold. Note that the reference shape T may be a square. X L <(1 / 2)×L …(2) X W <(1 / 2)×W …(3) (1 / 15)Vp≦ΣVn …(4) (1 / 10)×L < X L …(5) (1 / 7)×W < X W …(6)

[0026] Here, as shown in FIG. 4(d), any of the surfaces of the wall 9 extending in the Z-axis direction may have a recess 47 (substrate-side recess) at a position on the substrate 8 side in the Z-axis direction, and a cavity material 48 covering the substrate 8 may be provided at the position of the recess 47. The surfaces of the wall 9 extending in the Z-axis direction are the inner peripheral surface 13a, the outer peripheral surface 13b, and the side surface 30b and end surface 30c of the groove portion 30. Any of these surfaces 13a, 13b, 30b, 30c may have the recess 47. Further, the recess 47 does not have to be provided over the entire area of each of the surfaces 13a, 13b, 30b, 30c, and may be provided partially. The recess 47 is formed at a position closer to the substrate 8 than the tip portion 13c in the Z-axis direction. The recess 47 is formed at a position spaced upward from the main surface 8a of the substrate 8. Therefore, the cavity material 48 is formed between the recess 47 and the main surface 8a of the substrate 8. The recess 47 may extend in a direction in which the surfaces 13a, 13b, 30b, 30c 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 47, the recess 47 may be formed to extend in the Y-axis direction. Also, when the side surface 30b of the recess 30 of the wall frame portion 13A has the recess 47, the recess 47 may be formed to extend in the X-axis direction (see FIG. 4). Further, when the end surface 30c of the recess 30 of the wall frame portion 13A has the recess 47, the recess 47 may be formed to extend in the Y-axis direction (see FIG. 3).

[0027] The opening width of the recess 47, that is, the size w1 of the dimension in the Z-axis 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 48, 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 47 is not particularly limited, but may be set to 0 μm or more and 3 μm or less. Note that the recess 47 may be formed at a position directly above the substrate 8, and the cavity material 48 may not be formed. Such a structure is not preferable because the bonding strength between the wall 9 and the substrate 8 decreases, and the structure of FIG. 4(d) is more preferable.

[0028] Referring to FIGS. 5 and 6, a method for manufacturing the circuit board 3 and the mounting board 1 will be described. First, as shown in FIG. 5(a), terminals 10 are formed on the upper surface of the base material 8. Next, as shown in FIG. 5(b), a wall 9 is formed on the base material 8. Thereby, the circuit board 3 is completed. In FIG. 5(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. 5(c), by filling the cavity 11 with the component material 20, the component material 20 is disposed on the base material 8. Then, the electronic component 2 is held by a holding member and mounted in the cavity 11. Next, as shown in FIG. 6, with respect to the electronic component 2, the electronic component 2 is pushed into the cavity 11 by a pressure reflow device 49, and the bonding material 4A and the bonding material 4B are brought into contact with each other inside the component material 20. At this time, a part of the component material 20 is pushed out into the recessed 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. Thereby, the mounting board 1 is completed.

[0029] Next, referring to FIGS. 7 and 8, a method for forming the wall 9 having the recessed portion 30 will be described. First, as shown in FIG. 7(a), a wall 9 is formed on the base material 8. Next, as shown in FIG. 7(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. 7(c), a recessed portion 30 is formed in the wall 9.

[0030] Alternatively, as shown in FIG. 7(d), a resist 52 is formed on the base material 8. Next, as shown in FIG. 7(e), exposure is performed using a glass mask 53 having a pattern corresponding to the shape of the wall 9 having the recessed portion 30. As shown in FIG. 7(f), by developing the exposed resist 52, the wall 9 having the recessed portion 30 is formed.

[0031] Alternatively, as shown in Fig. 8(a), a wall 109 corresponding to a part on the inner peripheral side of the wall 9 is formed on the base material 8. Next, as shown in Fig. 8(b), the wall 109 is irradiated with a laser by the laser device 51 to process a part of the wall 109. As a result, as shown in Fig. 8(c), a shape of the recessed portion 30 is formed in the wall 109. Next, as shown in Fig. 8(d), by forming a wall 119 on the outer peripheral side of the wall 109, the wall 9 and the recessed portion 30 are formed.

[0032] In addition, when forming the shape of the recessed portion 47 shown in Fig. 4(d), the focus position of the exposure may be shifted above the film surface. Alternatively, the recessed portion 47 may be formed by overdevelopment.

[0033] 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.

[0034] First, with reference to Fig. 9, a circuit board 103 according to a comparative example will be described. The wall 9 of the circuit board 103 does not have the above-described recessed portion 30. After filling the inside of the wall 9 with the constituent material 20 and mounting the electronic component 2 into the wall 9 using a holding member, when trying 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 sufficiently pushed in. 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 that a connection failure may occur between the bonding material 4A of the circuit board 3 and the electronic component 2.

[0035] On the other hand, in the circuit board 3 according to the present embodiment, the terminals 10 (the first terminal and the second terminal) are arranged in the cavity 11 of the wall 9. Here, when viewed from the Z-axis direction (the first direction), the wall 9 has at least one recessed portion 30 that is recessed toward the outer peripheral side on the inner peripheral surface 13a of the cavity 11. In this case, when the constituent material 20 is arranged in the wall 9, an electronic component is mounted using a holding member, and the electronic component 2 is pushed into the wall 9 and heated using a pressure reflow device 49 and joined to the circuit board 3 to mount the electronic component 2 on the circuit board 3, the excess constituent material 20 can be discharged to the outside of the wall 9 through the recessed portion 30. As a result, in the pressing step using the pressure reflow device 49, the electronic component 2 can be sufficiently pushed into the wall 9 and brought into contact with the bonding material 4A. As described above, it is possible to suppress a connection failure between the bonding material 4A of the circuit board 3 and the electronic component 2.

[0036] The circuit board 3 may include a bonding material 4A (first bonding material) containing a metal element disposed on the terminal 10A and a bonding material 4A (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.

[0037] Let the volume of the recessed portion 30 be Vn, set a rectangular reference shape T that is the minimum area circumscribing the inner peripheral surface 13a of the wall 9 when viewed from the Z-axis direction, and let the volume obtained by multiplying the height (dimension in the first direction) of the wall 9 by the reference shape T be Vc, and let the volume of each bonding material 4 be Vp. In this case, Equation (1) may hold. In this case, it is possible to secure a volume for extruding the excess constituent material 20 into the recessed portion 30 and prevent the necessary amount of the constituent material 20 from flowing out of the cavity. ΣVn≦Vc - 2Vp …(1)

[0038] When viewed from the Z-axis direction, a rectangular reference shape T that is the minimum area circumscribing the inner peripheral surface 13a of the cavity 11 is set. Let the length of the side in the longitudinal direction (the first side) of the reference shape T be L, the length of the side in the short transverse direction (the second side) be W, and the maximum width of the opening width of the recessed portion 30 on the side in the longitudinal direction be X LLet the maximum width of the opening of the recess 30 on the side in the short side direction be X. W When this is the case, equations (2) and (3) may hold. In this case, it is possible to secure a volume for extruding the surplus structural material 20 into the recess 30, and it is possible to prevent the necessary amount of the structural material 20 from flowing out of the cavity. X L < (1 / 2)×L …(2) X W < (1 / 2)×W …(3)

[0039] When viewed from the inside of the cavity 11, the recess 30 extends from the tip portion 13c in the Z-axis direction of the wall frame portion 13 toward the base material 8 side, and the width of the recess 30 may be larger on the tip portion side than on the bottom surface side. In this case, by narrowing the width of the recess 30 on the base material 8 side, the flow path resistance can be increased. Thereby, by suppressing the unnecessary amount of the structural material 20 from flowing into the recess 30, the necessary amount of the structural material 20 can be held in the cavity 11. On the other hand, by widening the tip portion 13c side, it becomes easier to remove the surplus structural material 20.

[0040] 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 and the end surface 30c of the groove portion 30 has a recess 47 at a position on the base material 8 side in the Z-axis direction, and a cavity material 48 covering the base material 8 may be provided at the position of the recess 47. According to such a shape, the recess 47 can function as a guide groove through which the structural material 20 passes at the position on the base material 8 side. Therefore, the fluidity of the structural material 20 can be improved.

[0041] The edge portion 38 of the recess 30 may be rounded. In this case, it is possible to prevent the structural material 20 extruded against the recess 30 from staying at the edge portion 38, and the structural material can be poured in smoothly.

[0042] The manufacturing method of the mounting substrate 1 according to this 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. The manufacturing method may include arranging the constituent member 20 on the base material 8, arranging the electronic component 2, and then joining the electronic component 2 to the terminal 10 using the pressure reflow device 49.

[0043] In this case, the same functions and effects as those of the above-described circuit board 3 can be obtained.

[0044] 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.

[0045] As shown in FIG. 10(a), when the recessed portion 30 is viewed from the Z-axis direction, the width of the recessed portion 30 on the outer peripheral side, i.e., w2, may be larger than the width w1 on the inner peripheral surface 13a. In this case, by narrowing the width on the inner peripheral side of the recessed portion 30, pressure loss can be generated, and it is possible to suppress the constituent member 20 from being extruded more than necessary. In the figure, the width w2 of the end surface 30c on the outer peripheral side is larger than the opening width, i.e., w1, at the position of the inner peripheral surface 13a. In the example shown in FIG. 10(a), when the recessed portion 30 is viewed from the Z-axis direction, it is inclined so as to expand from the inner peripheral side to the outer peripheral side. The pair of side surfaces 30b are inclined with respect to the X-axis direction so that the distance between them increases as they go toward the outer peripheral side. In this case, in order to form a structure in which the width is narrowed on the inner peripheral surface 13a, it can be easily formed only by providing the inclination.

[0046] The structure in which the width of the recessed portion 30 is larger on the outer peripheral side width w2 than the width w1 on the inner peripheral surface 13a is not limited to that shown in Fig. 10(a). For example, the structure shown in Fig. 11 may be adopted. In Fig. 11, the recessed portion 30 may expand so as to form a step 36 from the inner peripheral side toward the outer peripheral side when viewed from the Z-axis direction. In this case, by forming the step 36, further pressure loss can be applied to the structural material 20. A protruding portion 37 is formed at the opening on the inner peripheral surface 13a of the recessed portion 30. The protruding portion 37 protrudes so as to approach each other from the side surfaces 30b on both sides toward the inner side in the width direction at the position of the opening of the recessed portion 30. A gap with a width w1 is formed between the pair of protruding portions 37. Thereby, a step 36 is formed between the protruding portion 37 and the side surface 30b on the outer peripheral side. The width w2 between the pair of side surfaces 30b is larger than the width w1 due to the gap between the pair of protruding portions 37.

[0047] As shown in Fig. 10(b), the edge portion 38 of the recessed portion 30 may be rounded. In this case, it is possible to prevent the structural material 20 extruded into the recessed portion 30 from staying at the edge portion 38. In Fig. 10(b), the edge portion 38 between the inner peripheral surface 13a and the side surface 30b of the recessed portion 30 is rounded. Since the edge portion 38 is rounded, the structural material 20 extruded from the cavity 11 into the recessed portion 30 is smoothly supplied into the recessed portion 30 without staying at the edge portion 38.

[0048] As shown in Figs. 12 to 15, the form of the wall 9 in the case where the circuit board 3 has a plurality of cavities 11 on the base material 8 will be described. As shown in Fig. 12, one wall 9 is provided with one cavity 11. The wall 9 has a gap with the adjacent wall 9. Different from Fig. 13, when the wall 9 is provided independently around the cavity 11, the thickness of each wall 9 is not particularly limited, but may be set to about 5μm to 200μm.

[0049] Alternatively, the configuration shown in FIG. 13 may be adopted. As shown in FIG. 13, the wall 9 may include a plurality of cavities 11. In this case, there is no break in the wall 9 between the cavity 11 and the adjacent cavity 11. In this case, the wall 9 is formed by a pattern (approximately uniformly formed) of a continuous insulating material that covers the main surface 8a of the base material 8. Also, the structure according to FIG. 14 may be adopted. In FIG. 14, only one recess 30 is provided for each cavity 11. Thus, the number of recesses 30 formed in each cavity 11 is not particularly limited. As shown in FIGS. 13 and 14, not limited to the periphery of the cavity 11, when covering a wide range of the surface of the base material 8, the surface of the base material 8 can be protected by the wall 9. When covering the region between the cavities 11 with the wall 9 without a gap, the surface of the base material 8 in the region can be protected by the wall 9. The vicinity of the edge of the base material 8 may or may not be covered by the wall 9.

[0050] As shown in FIG. 15(a), the circuit board 3 has a plurality of cavities 11 arranged in a matrix with respect to a pattern of a wall 9 formed of a continuous insulating material (approximately uniformly formed) that covers the main surface 8a of the base material 8 on the base material 8. For such a structure, as shown in FIG. 15(b), the recess 30 formed on the inner peripheral surface 13a of the cavity 11 may be connected to other cavities 11. The recess 30 extends in the Y-axis direction and connects the cavities 11 adjacent to each other in the Y-axis direction. The recess 30 extends in the X-axis direction and connects the cavities 11 adjacent to each other in the X-axis direction. In this case, even when the mounting density of the electronic component 2 on the base material 8 is increased, a sufficient volume for extruding the surplus structural material 20 can be ensured.

[0051] As shown in Fig. 16(a), when a rectangular reference shape T with the minimum area circumscribing the inner peripheral surface 16a of the cavity 11 is set when viewed from the Z-axis direction, the wall 9 may have recessed portions 30 at at least a pair of corner portions 19 on the diagonal of the reference shape T. In this case, since the side portion 18 of the wall frame portion can be left open, a slit or the like can be additionally provided at this position (see, for example, Figs. 16(b) and 16(c)). Also, since the corner portion 19 of the cavity 11 is the portion where the pressure of the constituent material 20 is most applied, providing the recessed portion 30 at this portion makes it easier to pour in the excess constituent material 20. Also, by providing recesses at a pair of diagonal corner portions 19, the excess constituent material 20 can be pushed out into the recessed portions in a well-balanced (substantially evenly) manner. The pair of diagonal corner portions 19 are "a combination of the corner portion 19 on the positive side in the X-axis direction and the positive side in the Y-axis direction and the corner portion 19 on the negative side in the X-axis direction and the negative side in the Y-axis direction", and "a combination of the corner portion 19 on the positive side in the X-axis direction and the negative side in the Y-axis direction and the corner portion 19 on the negative side in the X-axis direction and the positive side in the Y-axis direction". The recessed portion 30 may be provided only at one of the corner portions 19 of these combinations.

[0052] As in the example shown in Fig. 16(a), the wall 9 may have recessed portions 30 at each of the four corner portions 19 of the reference shape T. In this case, the constituent material 20 can be pushed out at all the corner portions 19 where the pressure is most applied. Also, the excess constituent material 20 can be pushed out into the recessed portions 30 in a well-balanced (substantially evenly) manner. As shown in Figs. 16(b) and 16(c), a slit 40 may be provided in the side portion 18 of the reference shape T. The slit 40 is a groove provided in the wall 9 and extends from the side portion 18 toward the outer peripheral side. As shown in Fig. 16(b), the slit 40 may extend from the side portion 18 to a predetermined distance. Alternatively, as shown in Fig. 16(c), the slit 40 may extend to an adjacent cavity 11.

[0053] As shown in FIG. 17(a), the tip portion 13c of the wall frame portion 13 of the wall 9 in the Z-axis direction may have a protruding edge portion 42 protruding in the Z-axis direction along the inner peripheral surface 13a. FIG. 17(b) is a plan view of FIG. 17(a). In the wall 9, the protruding edge portion 42 is the highest compared to other portions. In FIG. 17(b), the color is distinguished between the portion corresponding to the protruding edge portion 42 and other portions of the wall 9. The protruding edge portion 42 is formed to extend along the four-sided inner peripheral surface 13a so as to surround the entire circumference of the cavity 11. The circumferential thickness of the protruding edge portion 42 may be set to be the same as that of the recessed portion 30. According to the above configuration, the structural material 20 necessary for mounting is held in the cavity 11 by the protruding edge portion 42 on the inner peripheral surface 13a side, and when pressure is applied, it becomes easier to push the structural material 20 into the recessed portion 30. When the protruding edge portion 42 is provided at the position of the inner peripheral surface 13a, the opening of the recessed portion 30 becomes relatively narrow with respect to the entire inner peripheral surface 13a, so that the structural material 20 hardly flows into the recessed portion 30 in a low-pressure state. At the time of joining, the structural material 20 enters the recessed portion 30 by pressure.

[0054] As shown in FIG. 17(c), a groove edge portion 43 that is one step lower than other portions may be formed at a location adjacent to the outer peripheral side of the protruding edge portion 42. FIG. 17(d) is a plan view of FIG. 17(c). In FIG. 17(d), the color is distinguished between the portion corresponding to the protruding edge portion 42, the portion corresponding to the groove edge portion 43, and other portions of the wall 9. The groove edge portion 43 is provided so as to surround the protruding edge portion 42.

[0055] FIGS. 18(a) to (d) are schematic views showing a method of manufacturing the circuit board 3 shown in FIG. 17(a). As shown in FIG. 18(a), the protruding edge portion 42 is formed on the base material 8 with a negative resist. As shown in FIG. 18(b), a negative resist 45 is applied to the entire surface of the base material 8. As shown in FIG. 18(c), the portions other than the portion that becomes the wall 9 and the protruding edge portion 42 are covered with a mask 46. As shown in FIG. 18(d), the circuit board 3 is completed by exposure.

[0056] Figs. 18(e) to 18(h) are schematic views showing a method of manufacturing the circuit board 3 shown in Fig. 17(c). As shown in Fig. 18(g), when covering the protruding edge portion 42 with the mask 46, the mask 46 that is slightly wider than the protruding edge portion 42 is used for covering. Thereby, during exposure, due to refracted light, the polymerization reaction slightly proceeds, and the groove edge portion 43 remains as a residual film. As a result, as shown in Fig. 18(h), the groove edge portion 43 is formed. Note that other processes are the same as the manufacturing method shown in Figs. 18(a) to 18(d).

[0057] In the above-described embodiments and modifications, the recessed portion 30 was rectangular when viewed from the Z-axis direction, but it may be other polygons or circular.

[0058] [Embodiment 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 a 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 in a cavity formed in the wall, and when viewed from a first direction orthogonal to the main surface of the base material, the wall has at least one recessed portion that is recessed toward the outer peripheral side on the inner peripheral surface of the cavity, a circuit board. [Embodiment 2] A first bonding material containing a metal element disposed on the first terminal, and a second bonding material containing a metal element disposed on the second terminal, the circuit board according to Embodiment 1. [Embodiment 3] Let the volume of the recessed portion be Vn, when viewed from the first direction, a reference shape that is a rectangular shape having the minimum area circumscribing the inner peripheral surface of the cavity is set, and the volume obtained by multiplying the area of the reference shape by the dimension of the wall in the first direction is defined as Vc, when the volume of each bonding material is Vp, the circuit board according to Embodiment 1 or 2, for which the formula (1) holds. ΣVn ≦ Vc - 2Vp …(1) [Embodiment 4] When viewed from the first direction, a rectangular reference shape with the minimum area circumscribing the inner peripheral surface of the cavity is set. Let the length of the first side of the reference shape be L and the length of the second side be W. Let the maximum width of the opening of the recess formed on the first side be X L and let the maximum width of the opening of the recess formed on the second side be X W In the case where this is so, the circuit board according to any one of Forms 1 to 3 in which Expression (2) and Expression (3) are satisfied. X L < (1 / 2) × L …(2) X W < (1 / 2) × W …(3) [Form 5] When viewed from inside the cavity, the recess extends from the tip of the wall frame portion of the wall toward the base material side in the first direction. The width of the recess is larger on the tip side than on the bottom surface side. The circuit board according to any one of Forms 1 to 4. [Form 6] When the recess is viewed from the first direction, the width of the recess is larger on the outer peripheral side width than the width on the inner peripheral surface. The circuit board according to any one of Forms 1 to 5. [Form 7] When the recess is viewed from the first direction, the recess is inclined so as to expand from the inner peripheral side toward the outer peripheral side. The circuit board according to Form 6. [Form 8] At least any one of the inner peripheral surface, the outer peripheral surface of the wall, and the surface of the recess has a base material side recess at the position on the base material side in the first direction. At the position of the base material side recess, a cavity material covering the substrate is provided. The circuit board according to any one of Forms 1 to 7. [Form 9] When the recess is viewed from the first direction, the recess expands so as to form a step from the inner peripheral side toward the outer peripheral side. The circuit board according to Form 6. [Form 10] The circuit board according to any one of Forms 1 to 9, wherein the edge portion of the recessed portion is rounded. [Form 11] When a rectangular reference shape having the minimum area circumscribing the inner peripheral surface of the cavity is set when viewed from the first direction, the wall has the recessed portions at at least a pair of corner portions on the diagonal of the reference shape, respectively. The circuit board according to any one of Forms 1 to 10. [Form 12] The circuit board according to Form 11, wherein the wall has the recessed portions at each of the four corner portions of the reference shape. [Form 13] The circuit board according to any one of Forms 1 to 12, wherein a tip end portion of the wall frame portion of the wall in the first direction has a protruding edge portion protruding in the first direction along the inner peripheral surface. [Form 14] Having a plurality of the cavities on the base material, The circuit board according to any one of Forms 1 to 13, wherein the recessed portion of the inner peripheral surface of the cavity is connected to another cavity. [Form 15] A method for manufacturing a mounting board by mounting electronic components on the circuit board according to any one of Forms 1 to 14, A method for manufacturing a mounting board, 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.

Explanation of Signs

[0059] 3... Circuit board, 4A... Bonding material (first bonding material, second bonding material), 8... Base material, 9... Wall, 10... Terminals (first terminal, second terminal), 11... Cavity, 13A, 13B, 13C, 13D... Wall frame portion, 19... Corner portion, 20... Constituent material, 30... Groove portion, 38... Edge portion, 42... Protruding edge portion, 45... Recessed portion (base material side recessed portion), 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 a wall of an insulating material provided on the main surface of the base material, wherein the first and second terminals are disposed within a cavity formed in the wall, and when viewed from a first direction orthogonal to the main surface of the base material, the wall has at least one recessed portion that recesses outward on the inner peripheral surface of the cavity.

2. The circuit board according to claim 1, further comprising a first bonding material containing a metal element disposed on the first terminal and a second bonding material containing a metal element disposed on the second terminal.

3. Let the volume of the recessed portion be Vn, set a rectangular reference shape having the minimum area circumscribing the inner peripheral surface of the cavity when viewed from the first direction, and let the volume obtained by multiplying the area of the reference shape by the dimension of the wall in the first direction be Vc, The circuit board according to claim 2, wherein when the volume of each bonding material is Vp, the formula (1) holds. ΣVn ≦ Vc - 2Vp …(1)

4. Set a rectangular reference shape having the minimum area circumscribing the inner peripheral surface of the cavity when viewed from the first direction, let the length of the first side of the reference shape be L and the length of the second side be W, Let the maximum width of the opening of the recess of the first side be X Ｌ and Let the maximum width of the opening of the recess of the second side be X Ｗ The circuit board according to claim 1, wherein the expressions (2) and (3) are satisfied X Ｌ < (1 / 2) × L …(2) X Ｗ <(1 / 2) × W …(3)

5. When viewed from the inside of the cavity, the recessed portion extends from the tip of the wall frame portion of the wall in the first direction toward the base material side, The circuit board according to claim 1, wherein the width of the recessed portion is larger on the tip side than on the bottom side.

6. The circuit board according to claim 1, wherein when the recessed portion is viewed from the first direction, the width on the outer peripheral side is larger than the width on the inner peripheral surface.

7. The circuit board according to claim 6, wherein the recessed portion inclines so as to spread from the inner peripheral side to the outer peripheral side when viewed from the first direction.

8. At least any one of the inner peripheral surface, the outer peripheral surface of the wall, and the surface of the recessed portion has a recessed portion on the base material side 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 the position of the recessed portion on the base material side.

9. The circuit board according to claim 6, wherein the recessed portion spreads so as to form a step from the inner peripheral side to the outer peripheral side when viewed from the first direction.

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

11. When a rectangular reference shape having the minimum area circumscribing the inner peripheral surface of the cavity is set when viewed from the first direction, the wall has the recessed portions at at least a pair of corner portions on the diagonal of the reference shape, respectively. The circuit board according to claim 1.

12. The circuit board according to claim 11, wherein the wall has the recessed portions at each of the four corner portions of the reference shape.

13. The circuit board according to claim 1, wherein a tip portion of the wall frame portion of the wall in the first direction has a protruding edge portion protruding in the first direction along the inner peripheral surface.

14. having a plurality of the cavities on the base material, The circuit board according to claim 1, wherein the recessed portion of the inner peripheral surface of the cavity is connected to another cavity.

15. A method for manufacturing a mounting substrate, which comprises manufacturing a mounting substrate by mounting electronic components on the circuit board according to any one of claims 1 to 14, 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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