Structure with conductive pattern

Abstract

To provide a structure with a conductive pattern, in which a plurality of circuit boards is surely and electrically is connected in a sufficient mechanical strength, and has a space to be saved.SOLUTION: A structure 2 includes two or more circuit boards comprising: a substrate main body 6 having a first surface 6A and a second surface 6B as a back surface thereof; a convex-like through hole 10Q having an opening 16, which has a circular truncated cone-like outer side surface 12A and an upper surface 14A in which the first surface 6A is convex, a circular truncated cone-like inner side surface 12B and a ceiling surface 14B in which the second surface 6B is concave, the opening 16 penetrated between the upper surface 14A and the ceiling surface 14B; a connection layer 22 that is constructed so as to be connected by a conductive layer 22C to be formed in the opening 16; and a conductive pattern 20 that is formed to at least one of the first surface 6A and the second surface 6B, and is connected to the connection layer 22, the conductive pattern 20 having a fitting structure in which an insertion side outside surface 12A and an inserted side inner side surface 12B in which the connection layer 22 is formed are surface-contacted in a crimped state.SELECTED DRAWING: Figure 2B

Description

Technical Field

[0001] The present invention relates to a structure having a conductive pattern formed by connecting a plurality of circuit boards.

Background Art

[0002] In a circuit board on which a conductive pattern is formed, in order to realize a multifunctional circuit, it is desired to electrically connect a plurality of circuit boards. However, in order to connect a plurality of circuit boards, complicated wiring operations may be required. To avoid this, a structure has been proposed in which conductive pins are press-fitted into convex through-holes provided in two circuit boards and connected (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the structure described in Patent Document 1, since two circuit boards are connected using pins of a separate member, even though they are electrically connected, it is difficult to connect the circuit boards with sufficient mechanical strength. In order to connect the circuit boards with sufficient mechanical strength, additional connecting members are also required, resulting in an inability to achieve space savings and an increase in manufacturing costs. In particular, when using a circuit board having a three-dimensional shape called MID (Molded Interconnect Device), it becomes more difficult to arrange the pins and connecting members. Therefore, it is difficult to obtain a compact structure that is electrically and mechanically highly reliable.

[0005] Therefore, an object of the present invention is to provide a space-saving structure having a conductive pattern in which a plurality of circuit boards are surely electrically connected and connected with sufficient mechanical strength.

Means for Solving the Problems

[0006] The present invention includes the following aspects. [1] A substrate body having a region formed of a planar member having a predetermined thickness and having a first surface and a second surface which is the back surface thereof, A convex through-hole formed of the planar member, having a frustoconical outer surface and upper surface with the first surface being convex, and a frustoconical inner surface and ceiling surface with the second surface being concave, and having an opening penetrating between the upper surface and the ceiling surface, A connection layer configured by connecting a conductive layer formed on the outer surface and the upper surface of the convex through-hole and a conductive layer formed on the inner surface and the ceiling surface by a conductive layer formed in the opening, A conductive pattern formed on at least one of the first surface and the second surface and connected to the connection layer, Two or more circuit boards including the above are provided, An insertion-side outer surface which is the outer surface of the convex through-hole of one of the circuit boards and an inserted-side inner surface which is the inner surface of the convex through-hole of the other circuit board have the same taper angle, A structure having a conductive pattern, in which the insertion-side outer surface is inserted into an internal space surrounded by the inserted-side inner surface, and the insertion-side outer surface and the inserted-side inner surface on which the connection layer is formed are in surface contact in a crimped state.

[0007] [2] The taper angle is the elevation angle with respect to the virtual bottom surface of the frustoconical convex through-hole, The structure according to "[1]", wherein the taper angle is in the range of 40° or more and 80° or less.

[0008] [3] The structure according to "[1]" or "[2]", wherein the elastic modulus of the convex through hole of the one circuit board is different from the elastic modulus of the convex through hole of the other circuit board.

[0009] [4] The structure according to "[3]", wherein the elastic modulus of the convex through hole of the other circuit board is smaller than the elastic modulus of the convex through hole of the one circuit board.

[0010] [5] The structure according to any one of "[1]" to "[4]", wherein the hardness of the convex through hole of the one circuit board is different from the hardness of the convex through hole of the other circuit board.

[0011] [6] The structure according to any one of "[1]" to "[5]", wherein the thickness of the planar member covering the internal space of the convex through hole of the one circuit board is different from the thickness of the planar member covering the internal space of the convex through hole of the other circuit board.

[0012] [7] The inner diameter of the ceiling surface of the convex through hole of the other circuit board is smaller than the outer diameter of the upper surface of the convex through hole of the one circuit board, when the insertion-side outer surface and the inserted-side inner surface are in surface contact in a crimped state, there is a clearance between the upper surface and the ceiling surface, The structure according to any one of "[1]" to "[6]", wherein the insertion-side outer surface is in surface contact in a crimped state with the entire area of the inserted-side inner surface on the front side of the insertion direction with respect to the clearance region.

[0013] [8] The one circuit board and the other circuit board have convex through holes of the same shape, The structure according to "[7]", wherein the insertion-side outer surface is inserted into an internal space surrounded by the inserted-side inner surface having an inner diameter smaller than the outer diameter of the outer surface by the thickness of the planar member.

[0014] [9] The connection layer is divided in the circumferential direction and is composed of a plurality of divided connection layers insulated from each other. When the outer surface on the insertion side and the inner surface on the inserted side where the divided connection layer is formed are in surface contact in a crimped state, the divided connection layers formed on the outer surface on the insertion side and the inner surface on the inserted side are arranged at the same position in the circumferential direction. The structure according to any one of [1] to [8].

[0015]

[10] The conductive pattern formed on the first surface is connected to one of the divided connection layers, and the conductive pattern formed on the second surface is connected to the other divided connection layers. The structure according to [9].

[0016]

[11] It includes two or more connecting parts that connect the end of the substrate body of one circuit board and the end of the substrate body of the other circuit board. The distance between the one circuit board and the other circuit board at the position of the connecting part is shorter than the distance between the one circuit board and the other circuit board at the position of the fitted convex through hole. The structure according to any one of [1] to

[10] .

[0017]

[12] A plurality of the convex through holes are formed in one of the circuit boards. The structure according to any one of [1] to

[11] .

[0018]

[13] Three or more of the circuit boards are connected by the convex through holes. The structure according to any one of [1] to

[12] .

[0019]

[14] The circuit board is a MID (Molded Interconnect Device) having a three-dimensional shape. The structure according to any one of [1] to

[13] .

[0020]

[15] The structure according to any one of [1] to

[14] , wherein 70% or more of the area of the outer surface on the insertion side is in surface contact with the inner surface on the inserted side in a pressure-bonded state.

Advantages of the Invention

[0021] According to one aspect of the present invention, it is possible to provide a space-saving structure having a conductive pattern in which a plurality of circuit boards are surely electrically connected and connected with sufficient mechanical strength.

Brief Description of the Drawings

[0022]

Figure 1A

Figure 1B

Figure 2A

Figure 2B

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 5C

Figure 5D

Figure 5E

Figure 6A

Figure 6B

Figure 7A

Figure 7B

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0023] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In each drawing, corresponding members having the same function are denoted by the same reference numerals. For the sake of clarity of explanation or ease of understanding, the embodiments may be shown separately for convenience, but partial substitution or combination of the configurations shown in different embodiments is possible. In the embodiments described below, descriptions of matters common to the foregoing embodiments will be omitted, and only the different points will be described. In particular, the same operational effects due to the same configurations will not be sequentially mentioned for each embodiment. The sizes, positional relationships, etc. of the members shown in the drawings may be exaggerated for the sake of clarity of explanation.

[0024] (Circuit Board) In the present invention, a plurality of circuit boards are stacked to form a structure having a conductive pattern. The circuit boards to be stacked include a substrate body having a flat plate shape or any other three-dimensional shape. The substrate body can be manufactured by molding, but can also be manufactured by laser processing or the like from a member having a certain shape.

[0025] First, with reference to FIGS. 1A and 1B, a circuit board constituting a structure having a conductive pattern will be outlined. In the following, a substrate body having a flat plate shape will be taken as an example for explanation. FIGS. 1A and 1B are perspective views schematically showing an example of a circuit board constituting a structure having a conductive pattern according to the present invention, FIG. 1A shows the first surface side, and FIG. 1B shows the second surface side. The second surface is the back surface of the first surface, and by rotating the circuit board 180 degrees in the direction indicated by the arrow in FIG. 1A, the state shown in FIG. 1B is obtained.

[0026] The circuit board 4 shown in FIGS. 1A and 1B includes a substrate body 6 formed of a planar member having a predetermined thickness and having a first surface 6A and a second surface 6B which is the back surface thereof. A planar member has a non-blocky shape in which the distance (thickness) between the first surface and the second surface on the back surface thereof is small compared to the sizes of the first surface and the second surface. The first surface 6A and the second surface 6B on the back surface thereof may have not only a flat surface but also an arbitrary curved surface, uneven surface, bent portion, etc. The predetermined thickness of the planar member is not limited to a constant thickness, and the thickness may vary depending on the region.

[0027] The substrate body 6 described below has a flat plate shape in which all regions are formed of a planar member, but is not limited thereto. As long as at least the region where the convex through-holes 10 described later are arranged has a planar member, a substrate body having any other three-dimensional shape including a block-shaped region can be used.

[0028] The substrate body 6 integrally formed of a planar member has convex through-holes 10. In the illustrated example, four convex through-holes 10 (10P(10P(1), 10P(2)), 10Q, 10R) are integrally formed in the substrate body 6. Here, the convex through-hole is a general term for a structure that electrically connects between conductive patterns formed on both surfaces of a circuit board or between conductive patterns of a plurality of stacked circuit boards by a conductive portion formed in an opening. A plurality of circuit boards 4 can be electrically and mechanically connected through the convex through-holes 10 electrically connected to the conductive patterns.

[0029] As the material of the substrate body 6, inorganic materials and organic materials can be used. Examples of inorganic materials include ceramics and the like, and examples of organic materials include resins and the like. As the ceramics, a silicon nitride sintered body, a sialon sintered body, a silicon carbide sintered body, an alumina sintered body, an aluminum nitride sintered body, etc. can be preferably used. In addition to these ceramics, a metal formed and subjected to insulation processing on the surface may be used.

[0030] As the resin, a thermosetting resin or a thermoplastic resin can be preferably used. Examples of thermosetting resins include epoxy resins, melamine resins, phenolic resins, urea resins, unsaturated polyester resins, etc. Examples of thermoplastic resins include polyethylene, polypropylene, polystyrene, ABS resin, vinyl chloride resin, methyl methacrylate resin, nylon, polyester resin, fluororesin, polycarbonate, polyacetal, polyamide, polyphenylene ether, amorphous polyarylate, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyimide, polyetherimide, liquid crystal polymer, etc.

[0031] The convex through hole 10 has a frustoconical outer surface 12A and upper surface 14A with the first surface 6A being convex, and a frustoconical inner surface 12B and ceiling surface 14B with the second surface 6B being concave, and has an opening 16 penetrating between the upper surface 14A and the ceiling surface 14B. Among such convex through holes 10, different types of convex through holes 10P, 10Q, 10R are formed in the circuit board 4 shown in FIGS. 1A and 1B.

[0032] Hereinafter, each type of convex through holes 10P, 10Q, 10R will be described in detail. For the common parts of the convex through holes regardless of the type of convex through holes such as those in FIGS. 3, 4, and 8 to 10, the convex through hole is indicated by the reference numeral 10, and in the description of each type, they are indicated by the reference numerals 10P, 10Q, 10R respectively.

[0033] (Convex Through-Hole According to the First Embodiment) First, with reference to FIGS. 2A and 2B, a convex through-hole 10 according to the first embodiment of the present invention will be described. FIG. 2A is a side cross-sectional view schematically showing the convex through-hole according to the first embodiment of the present invention showing a cross-section A-A of FIGS. 1A and 1B, and is a view showing an example in which a conductive pattern is formed on the first surface. FIG. 2B is a side cross-sectional view schematically showing the convex through-hole according to the first embodiment of the present invention showing a cross-section B-B of FIGS. 1A and 1B, and is a view showing an example in which a conductive pattern is formed on the second surface. In any of the figures, the thicknesses of the connection layer and the conductive pattern are shown thicker than the actual ones.

[0034] The convex through-holes 10P and 10Q according to the first embodiment are integrally formed of the same material as the substrate body 6. However, it is not limited thereto, and it can also be formed of a material different from the substrate body 6 by two-color molding or the like. The convex through-holes 10P and 10Q are formed with a side surface portion 12 that constitutes the side surface of a truncated cone and an upper surface portion 14 that constitutes the upper surface of the truncated cone by a planar member. In the convex through-holes 10P and 10Q, the side surface portion 12 is formed so as to have a taper angle of angle θ. Here, the taper angle θ is the elevation angle with respect to the virtual bottom surface of the truncated cone-shaped convex through-hole 10. Note that the taper angle is shown as the angle formed by the center line of the cone perpendicular to the virtual bottom surface in a virtual cone obtained by extending the outer surface of the convex through-hole 10. In that case, the angle is the value of 90° - θ.

[0035] An opening 16, which is a through-hole, is formed in the upper surface portion 14 of the convex through-holes 10P and 10Q. The bottom surface of the truncated cone is open, and an internal space S is formed. The outer surface of the convex through-holes 10P and 10Q is composed of an outer surface 12A by the side surface portion 12 and an upper surface 14A by the upper surface portion 14. On the other hand, the inner surface of the convex through-holes 10P and 10Q is composed of an inner surface 12B by the side surface portion 12 and a ceiling surface 14B by the upper surface portion 14. That is, an internal space S is formed surrounded by the inner surface 12B and the ceiling surface 14B.

[0036] The convex through-holes 10P and 10Q are formed with a conductive connection layer 22. More specifically, as the connection layer 22, an outer surface side connection layer 22A is formed on the outer surface 12A of the convex through-holes 10P and 10Q, an inner surface side connection layer 22B is formed on the inner surface 12B, and a conductive layer 22C that connects the outer surface side connection layer 22A and the inner surface side connection layer 22B is formed in the opening 16.

[0037] Also, in the convex through-hole 10P, a conductive pattern 20 is formed on the first surface 6A of the substrate body 6, and the conductive pattern 20 is connected to the outer surface side connection layer 22A that constitutes the connection layer 22. On the other hand, in the convex through-hole 10Q, a conductive pattern 20 is formed on the second surface 6B of the substrate body 6, and the conductive pattern 20 is connected to the inner surface side connection layer 22B that constitutes the connection layer 22. In any of the conductive patterns 20, not only circuit patterns but also electronic components electrically connected to the circuit patterns may be attached. Note that there may be a case where conductive patterns 20 are formed on both the first surface 6A and the second surface 6B of the substrate body 6, and the conductive patterns 20 on both surfaces are connected by the connection layer 22.

[0038] The conductive pattern 20 and the connection layer 22 can be formed of materials such as copper (Cu), nickel (Ni), palladium (Pd), silver (Ag), gold (Au), platinum (Pt), tin (Sn), iron (Fe), cobalt (Co), chromium (Cr), rhodium (Rh), ruthenium (Ru), etc., and it is preferable to apply copper plating or the like.

[0039] As the thickness of the substrate body 6, a range of 0.2 mm or more and 5.0 mm or less can be exemplified. As the thickness of the side portions 12 and the upper surface portions 14 of the convex through holes 10P and 10Q, a range of 0.2 mm or more and 5.0 mm or less can be exemplified. The thickness of the upper surface portion 14 of the convex through holes 10P and 10Q may be the same as or different from the thickness of the side portion 12. The thickness of the side portions 12 and the upper surface portions 14 of the convex through holes 10P and 10Q may be the same as or different from the thickness of the substrate body 6. As the outer diameter of the upper surface portion 14 of the frustum-shaped convex through holes 10P and 10Q, a range of 0.2 mm or more and 10.0 mm or less can be exemplified, and as the height, a range of 0.2 mm or more and 10.0 mm or less can be exemplified.

[0040] (Fitting structure of convex through holes) Next, with reference to FIG. 3, the fitting structure of the convex through hole 10 will be described. FIG. 3 is a side cross-sectional view schematically showing a structure in which the convex through hole of one circuit board is fitted with the convex through hole of the other circuit board. Since the thickness of the connection layer formed on the outer surface of the convex through hole 10 is very thin, it is omitted in the drawing. In FIG. 3, in order to clearly show arrows and the like, one circuit board 4A is shown by light coloring instead of hatching.

[0041] FIG. 3 shows a part of the structure 2 having a conductive pattern formed by connecting one circuit board 4A and the other circuit board 4B by fitting the convex through hole 10. The insertion-side outer surface 12A(4A), which is the outer surface of the convex through hole 10 of one circuit board 4A, is inserted into the internal space SB surrounded by the inserted-side inner surface 12B(4B), which is the inner surface of the convex through hole 10 of the other circuit board 4B. The shapes of the convex through holes 10 of one circuit board 4A and the convex through holes 10 of the other circuit board 4B may be the same or different. Note that FIG. 3 shows a case where the shapes of the convex through holes 10 are different. In any case, the insertion-side outer surface 12A(4A) of one circuit board 4A and the inserted-side inner surface 12B(4B) of the other circuit board 4B have the same taper angle θ.

[0042] Furthermore, in the present embodiment, the inner diameter D2(4B) of the ceiling surface 14B of the convex through hole 10 of one circuit board 4B is smaller than the outer diameter D1(4A) of the upper surface 14A of the convex through hole 10 of the other circuit board 4A to be inserted. In other words, the inner diameter D2(4B) of the end portion on the back side in the insertion direction of the inner surface 12B(4B) on the inserted side is smaller than the outer diameter D1(4A) of the end portion on the back side in the insertion direction of the outer surface 12A(4A) on the inserting side. Thereby, even when the convex through hole 10 of one circuit board 4A is pushed to the deepest part of the internal space SB, a predetermined clearance CT can be secured between the upper surface 14A of the convex through hole 10 of one circuit board 4A and the ceiling surface 14B of the convex through hole 10 of the other circuit board 4B.

[0043] Since the outer surface 12A(4A) on the inserting side and the inner surface 12B(4B) on the inserted side have the same taper angle θ, when the convex through hole 10 of one circuit board 4A is pushed to the deepest part of the internal space SB, the outer surface 12A(4A) is in surface contact with the inner surface 12B(4B) on the inserted side in a crimped state over the entire area of the inner surface 12B(4B) on the inserted side on the front side in the insertion direction than the region of the clearance CT.

[0044] That is, when the outer surface 12A(4A) on the inserting side of one circuit board 4A is inserted into the back side of the space SB surrounded by the inner surface 12B(4B) on the inserted side of the other circuit board 4B, the inner diameter id(h) of the inner surface 12B(4B) on the inserted side corresponding to the position h in the insertion direction (h = 0 at the insertion port) decreases along the taper, and at the position where the inner diameter id(h) of the inner surface 12B(4B) on the inserted side coincides with the outer diameter D1(4A) of the upper surface 14A of the outer surface 12A(4A) on the inserting side, it becomes impossible to insert any further. At this time, a clearance CT is generated between the upper surface 14A of the convex through hole 10 of one circuit board 4A and the ceiling surface 14B of the convex through hole 10 of the other circuit board 4B, and in the entire area where the outer surface 12A(4A) on the inserting side is inserted into the internal space SB, an engagement structure can be obtained in which the outer surface 12A(4A) on the inserting side and the inner surface 12B(4B) on the inserted side where the connection layer 22 is formed are in surface contact in a crimped state.

[0045] As a result, one circuit board 4A and the other circuit board 4B are connected with sufficient mechanical strength. Furthermore, since the connection layers 22 formed in the convex through holes 10 of one circuit board 4A and the other circuit board 4B are crimped to each other, an efficient connection with low contact resistance can be achieved electrically, and additional operations such as soldering are not required. For this reason, since one circuit board 4A and the other circuit board 4B can be connected at a short interval, a compact structure 2 can be realized.

[0046] As described above, the inner diameter D2(4B) of the ceiling surface 14B of the convex through hole 10 of the other circuit board 4B is smaller than the outer diameter D1(4A) of the upper surface 14A of the convex through hole 10 of one circuit board 4A. When the outer surface 12A(4A) on the insertion side and the inner surface 12B(4B) on the inserted side are in surface contact in a crimped state, there is a clearance CT between the upper surface 14A(4A) and the ceiling surface 14B(4B), and over the entire area of the inner surface 12B(4B) on the inserted side on the front side in the insertion direction rather than the region of the clearance CT, it is in surface contact with the outer surface 12A(4A) on the insertion side in a crimped state.

[0047] As a result, one circuit board 4A and the other circuit board 4B can be surely electrically connected, and a fitting structure connected with sufficient mechanical strength can be obtained. Considering the manufacturing tolerance of the convex through hole 10, it is preferable to make the clearance CT small in the range where the outer surface 12A(4A) on the insertion side and the inner surface 12B(4B) on the inserted side are surely in surface contact in a crimped state. Considering the elastic deformation of the convex through hole 10 as well, in the state where the outer surface 12A(4A) on the insertion side and the inner surface 12B(4B) on the inserted side are actually in surface contact in a crimped state, there may be no clearance, and the upper surface 14A of the convex through hole 10 of one circuit board 4A may be in contact with the ceiling surface 14B of the convex through hole 10 of the other circuit board 4B. In that case, the conductive layer 22C formed on the upper surface 14A of the convex through hole 10 of one circuit board 4A and the conductive layer 22C formed on the ceiling surface 14B of the convex through hole 10 of the other circuit board 4B are electrically in contact, and a more efficient electrical connection can be expected.

[0048] <Taper angle> When the insertion-side outer surface 12A(4A) of the circuit board 4A is pushed into the back side of the internal space SB to press the inserted-side inner surface 12B(4B) of the other circuit board 4B, a wedge effect due to the taper angle θ occurs. If the force for pushing the insertion-side outer surface 12A(4A) into the back side of the internal space SB is F, and the force of the wedge effect (the force over the entire circumference) in the direction perpendicular to the insertion-side outer surface 12A(4A) and the inserted-side inner surface 12B(4B) is P, then P = F / Sin(90° - θ) = F / Cos(θ) has the relationship. In the above formula, the friction term is omitted for simplicity. As is clear from the above formula, the larger the taper angle θ (closer to 90°), the greater the wedge effect, and the surface pressure between the insertion-side outer surface 12A(4A) and the inserted-side inner surface 12B(4B) can be increased.

[0049] On the other hand, if the predetermined clearance is CT, then D1(4A) = D2(4B) + 2 × CT / Tan(θ) has the relationship, so CT = (D1(4A) - D2(4B)) × Tan(θ) / 2 D1(4A) > D2(4B) results.

[0050] Also, if the change in the inner diameter of the inner surface 12B is ΔD, and the position change in the insertion direction (the position change in the direction perpendicular to the virtual bottom surface of the frustum of a cone) accompanying the change in the inner diameter ΔD is Δh, then, similar to the case of the clearance CT, Δh = ΔD × Tan(θ) / 2 results.

[0051] As the taper angle θ increases (approaches 90°), the value of Tan(θ) increases, so the clearance CT increases, and due to the change ΔD in the inner diameter of the inserted-side inner surface 12B(4B), the position change Δh in the insertion direction increases. Considering the tolerance of the resin molded body, when the taper angle θ is large, the position where the inner diameter of the inserted-side inner surface 12B(4B) coincides with the outer diameter D1(4A) of the upper surface 12A of the insertion-side outer surface 12A(4A) in the insertion direction is likely to vary.

[0052] Therefore, for example, when aligning circuit boards 4 having a plurality of convex through-holes 10, there is a possibility that the distances between one circuit board 4A and the other circuit board 4B may be different due to the individual convex through-holes 10. In that case, the circuit board 4 may bend, and there is a possibility that one circuit board 4A and the other circuit board 4B may not be properly connected.

[0053] Considering these opposing events, it can be said that the taper angle θ is preferably in the range of 40° or more and 80° or less, and more preferably in the range of 50° or more and 70° or less. By having the convex through-hole 10 with such a range of taper angle θ, the insertion-side outer surface 12A(4A) and the inserted-side inner surface 12B(4B) can be strongly surface-contacted by the wedge effect, and the variation in the distance between one circuit board 4A and the other circuit board 4B into which the convex through-hole 10 is fitted can be suppressed.

[0054] With the above structure, it is preferable that 70% or more of the region of the insertion-side outer surface 12A(4A) is surface-contacted with the inserted-side inner surface 12B(4B) in a crimped state, and more preferably 80% or more of the region is surface-contacted with the inserted-side inner surface 12B(4B) in a crimped state. Thereby, the circuit board 4A and the other circuit board 4B can be firmly connected, and the distance between the circuit boards can be reduced to obtain a compact laminated structure.

[0055] <Elastic modulus of the convex through-hole> In the fitting structure in which the insertion-side outer surface 12A(4A) and the inserted-side inner surface 12B(4B) are surface-contacted in a crimped state, it is considered that the fitting convex through-hole 10 elastically deforms within a slight range that does not affect the connection layer 22. Therefore, in order to obtain a more stable fitting structure, it is preferable that the elastic modulus of the convex through-hole 10 of one circuit board 4A is different from the elastic modulus of the convex through-hole 10 of the other circuit board 4B. Thereby, when the convex through-holes 10 are fitted, the convex through-holes 10 having a low elastic modulus mainly elastically deform, and a stable fitting structure can be obtained.

[0056] As specific numerical values of the elastic modulus, for example, either one of the tensile elastic moduli can be about 2000 to 25000 MPa, and the other tensile elastic modulus can be about 1600 to 22000 MPa. However, it is not limited to this, and any other arbitrary elastic coefficient can be adopted.

[0057] Thus, when the elastic modulus of the convex through-hole 10 of one circuit board 4A is different from the elastic modulus of the convex through-hole 10 of the other circuit board 4B, the insertion-side outer surface 12A(4A) and the inserted-side inner surface 12B(4B) can be more stably surface-contacted in a crimped state.

[0058] Since it is a slight elastic deformation, the elastic modulus of either one of the fitting convex through-holes 10 can be smaller. However, generally, the deformation in the expanding direction is expected to be more uniform without buckling or the like than the deformation in the shrinking direction. From this viewpoint, it can be said that it is more preferable that the elastic modulus of the convex through-hole 10 of the other circuit board 4B in which elastic deformation in the expanding direction occurs is smaller than the elastic modulus of the convex through-hole 10 of one circuit board 4A. Thereby, more uniform elastic deformation occurs in the fitting convex through-holes 10, and a fitting structure that more stably makes surface contact in a crimped state can be obtained.

[0059] <Hardness of the convex through-hole> Even when the hardnesses of the fitting convex through-holes 10 are different, the same effects as those in the case where the elastic moduli are different can be obtained. It is preferable that the hardness of the convex through-hole 10 of one circuit board 4A is different from the hardness of the convex through-hole 10 of the other circuit board 4B. For example, either one of the tensile elastic moduli can be about Rockwell R65 to 100, and the other tensile elastic modulus can be about Rockwell R80 to 130. However, it is not limited to this, and resin materials with any other arbitrary hardness can be adopted.

[0060] Thus, when the hardness of the convex through-hole 10 of one circuit board 4A is different from the hardness of the convex through-hole 10 of the other circuit board 4B, the insertion-side outer surface 12A(4A) and the inserted-side inner surface 12B(4B) can be more stably brought into surface contact in a crimped state.

[0061] Also, similar to the case of the elastic modulus, it can be said that it is more preferable that the hardness of the convex through-hole 10 of the other circuit board 4B where elastic deformation occurs in the expanding direction is lower than the hardness of the convex through-hole 10 of one circuit board 4A.

[0062] <Thickness of the planar member covering the internal space of the convex through-hole> Furthermore, even when the thickness of the planar member covering the internal space SA of the convex through-hole 10 of one circuit board 4A is different from the thickness of the planar member covering the internal space SB of the convex through-hole 10 of the other circuit board 4B, an effect similar to the case where the elastic moduli are different can be obtained.

[0063] Thus, when the thickness of the planar member covering the internal space SA of the convex through-hole 10 of one circuit board 4A is different from the thickness of the planar member covering the internal space SB of the convex through-hole 10 of the other circuit board 4B, the insertion-side outer surface 12A(4A) and the inserted-side inner surface 12B(4B) can be more stably brought into surface contact in a crimped state.

[0064] Also, similar to the case of the elastic modulus, it can be said that it is more preferable that the thickness of the planar member covering the internal space SB of the convex through-hole 10 of the other circuit board 4B where elastic deformation occurs in the expanding direction is thinner than the thickness of the planar member covering the internal space SA of the convex through-hole 10 of one circuit board 4A.

[0065] (Mating structure of convex through-holes of the same shape) Next, with reference to FIG. 4, a description will be given of a structure in which the circuit board 4 is connected by fitting the convex through-holes 10 having the same shape. FIG. 4 is a side cross-sectional view schematically showing a structure in which the convex through-holes of one circuit board are fitted with the convex through-holes of the other circuit board in a circuit board having convex through-holes of the same shape.

[0066] Also in FIG. 4, a part of the structure 2 having a conductive pattern formed by connecting one circuit board 4A and the other circuit board 4B by fitting the convex through-holes 10 is shown. In FIG. 4, the convex through-holes 10 having the same shape are fitted, and the circuit boards 4A and 4B are connected. Therefore, the inner diameter of the inner surface 12B of the convex through-hole 10 is formed smaller than the outer diameter of the outer surface 12A by the thickness t of the planar member covering the internal space S. Therefore, when the convex through-holes 10 having the same shape are fitted to each other, it is considered that a predetermined clearance CT can be obtained.

[0067] More specifically, if the inner diameter of the ceiling surface 14B of the insertion-side inner surface 12B(4B) of the other circuit board 4B is D2(4B), the outer diameter of the upper surface 14A of the insertion-side outer surface 12A(4A) of one circuit board 4A is D1(4A), and the thickness of the side portion 12 and the upper surface portion 14 of the convex through-hole 10 is t, the following relationship holds. D2(4B)=D1(4A)+2×t / Tan - 2×t / Sin(θ)

[0068] To have the clearance CT, it is necessary to have the relationship D2(4B)<D1(4A), D1(4A)+2×t / Tan - 2×t / Sin(θ)<D1(4A) which is necessary. Rearranging the above formula, Cos(θ)<1 This results in the taper angle θ not being 90°. Therefore, when the convex through-holes 10 of the same shape are engaged, a predetermined clearance CT can always be provided. Although there may be cases where the clearance CT is not provided as described above, when the clearance CT is provided, it is possible to suppress unintentional conduction (short circuit) between circuits, which is particularly effective when there is no solder resist.

[0069] As described above, when one circuit board 4A and the other circuit board 4B have convex through-holes 10 of the same shape, the insertion-side outer surface 12A(4A) is inserted into the internal space SB surrounded by the inserted-side inner surface 12B(4B) having an inner diameter smaller than the outer diameter of the outer surface 12A(4B) by the thickness t of the planar member.

[0070] Since the structure 2 can be formed using the same circuit board 4, the manufacturing cost of the structure 2 can be reduced. At the same time, a predetermined clearance CT can be reliably ensured, and the insertion-side outer surface 12A(4A) can be surely brought into surface contact with the inserted-side inner surface 12B(4B) in a pressure-bonded state over the entire area of the inserted-side inner surface 12B(4B) on the front side in the insertion direction with respect to the region of the clearance CT.

[0071] Although the thickness of the upper surface portion 14 of the convex through-hole 10 may be slightly thicker than the thickness of the side surface portion 12, it is unlikely to significantly increase the thickness of the upper surface portion 14 from the perspective of forming the opening 16, which is a through-hole. If the taper angle θ is in the range of 40° or more and 80° or less, it is considered that the relationship D2(4B) < D1(4A) always holds. Note that the mating structure described with reference to FIGS. 3 and 4 is applicable not only to the convex through-hole 10 according to the first embodiment described above but also to the convex through-holes 10 according to all the embodiments described below.

[0072] (Connection of Conductive Patterns Formed on Circuit Board) Next, with reference to FIGS. 5A to 5E, various modes in which the conductive pattern 20 of one circuit board 4A and the conductive pattern 20 of the other circuit board 4B are electrically connected by fitting the convex through hole 10 according to the first embodiment will be described. FIGS. 5A to 5E are diagrams schematically showing examples in which the conductive pattern of one circuit board and the conductive pattern of the other circuit board are electrically connected in a structure having a circuit board with a convex through hole according to the first embodiment. FIG. 5A shows a first example, FIG. 5B shows a second example, FIG. 5C shows a third example, FIG. 5D shows a fourth example, and FIG. 5E shows a fifth example.

[0073] <First example> In the first example shown in FIG. 5A, both the one circuit board 4A on the insertion side and the other circuit board 4B on the insertion side have a convex through hole 10P in which the conductive pattern 20 is formed on the first surface 6A as shown in FIG. 2A. Thereby, a structure 2 in which the conductive pattern 20 formed on the first surface 6A of one circuit board 4A and the conductive pattern 20 formed on the first surface 6A of the other circuit board 4B are electrically connected is obtained.

[0074] <Second example> In the second example shown in FIG. 5B, both the one circuit board 4A on the insertion side and the other circuit board 4B on the insertion side have a convex through hole 10Q in which the conductive pattern 20 is formed on the second surface 6B as shown in FIG. 2B. Thereby, a structure 2 in which the conductive pattern 20 formed on the second surface 6B of one circuit board 4A and the conductive pattern 20 formed on the second surface 6B of the other circuit board 4B are electrically connected is obtained.

[0075] <Third example> In the third example shown in FIG. 5C, one circuit board 4A on the insertion side has a convex through-hole 10Q in which a conductive pattern 20 is formed on the second surface 6B as shown in FIG. 2B, and the other circuit board 4B on the inserted side has a convex through-hole 10P in which a conductive pattern 20 is formed on the first surface 6A as shown in FIG. 2A. Thereby, a structure 2 is obtained in which the conductive pattern 20 formed on the second surface 6B of one circuit board 4A and the conductive pattern 20 formed on the first surface 6A of the other circuit board 4B are electrically connected.

[0076] <Fourth Example> In the fourth example shown in FIG. 5D, one circuit board 4A on the insertion side has a convex through-hole 10P in which a conductive pattern 20 is formed on the first surface 6A as shown in FIG. 2A, and the other circuit board 4B on the inserted side has a convex through-hole 10Q in which a conductive pattern 20 is formed on the second surface 6B as shown in FIG. 2B. Thereby, a structure 2 is obtained in which the conductive pattern 20 formed on the first surface 6A of one circuit board 4A and the conductive pattern 20 formed on the second surface 6B of the other circuit board 4B are electrically connected.

[0077] <Fifth Example> In the fifth example shown in FIG. 5E, conductive patterns 20 are formed on both the first surface 6A and the second surface 6B of one circuit board 4A on the insertion side and are connected by a connection layer 22, and conductive patterns 20 are formed on both the first surface 6A and the second surface 6B of the other circuit board 4B on the inserted side and are connected by a connection layer 22. Therefore, a structure 2 is obtained in which the conductive patterns 20 formed on both surfaces of one circuit board 4A and the other circuit board 4B are electrically connected by the mating convex through-holes 10.

[0078] As described above, by the convex through-hole 10 according to the first embodiment of the present invention, a structure 2 having various circuit patterns can be obtained.

[0079] (Convex Through-Hole According to the Second Embodiment) Next, with reference to FIGS. 6A and 6B, a description will be given of the convex through-hole according to the second embodiment of the present invention. FIG. 6A is a side cross-sectional view schematically showing the convex through-hole according to the second embodiment of the present invention, which shows a cross-section C-C of FIGS. 1A and 1B, and is a view showing an example in which conductive patterns are formed on the first and second surfaces. FIG. 6B is a plan cross-sectional view of the fitting state seen from the position of the cross-section D-D of FIG. 6A, schematically showing a state in which the convex through-holes of one circuit board having the convex through-hole according to the second embodiment are fitted with the convex through-holes of the other circuit board. In any of the figures, the thicknesses of the connection layer and the conductive pattern are shown thicker than the actual ones. Also in this embodiment, if a fitting structure that makes surface contact in the crimped state is obtained, the clearance CT may or may not exist.

[0080] As shown in FIG. 6B, the convex through-hole 10R formed in the circuit board 4 according to this embodiment has a connection layer composed of two divided connection layers 24 and 26 that are divided in the circumferential direction and insulated from each other. A sufficient insulating space is secured between the two divided connection layers 24 and 26. Further, the insulating space can be filled with an insulating material.

[0081] Describing the divided connection layers 24 and 26 in more detail, as the left divided connection layer 24 in FIGS. 6A and 6B, an outer surface side connection layer 24A is formed on the outer surface 12A of the convex through-hole 10R, an inner surface side connection layer 24B is formed on the inner surface 12B, and a conductive layer 24C connecting the outer surface side connection layer 24A and the inner surface side connection layer 24B is formed in the opening 16. Similarly, as the right divided connection layer 26 in FIGS. 6A and 6B, an outer surface side connection layer 26A is formed on the outer surface 12A of the convex through-hole 10R, an inner surface side connection layer 26B is formed on the inner surface 12B, and a conductive layer 26C connecting the outer surface side connection layer 26A and the inner surface side connection layer 26B is formed in the opening 16.

[0082] In the example shown in FIG. 6A, the conductive pattern 20 formed on the first surface 6A of the circuit board 4 is connected to the split connection layer 24, and the conductive pattern 20 formed on the second surface 6B is connected to the split connection layer 26. However, it is not limited to this. Conversely, the conductive pattern 20 formed on the first surface 6A of the circuit board 4 may be connected to the split connection layer 26, and the conductive pattern 20 formed on the second surface 6B may be connected to the split connection layer 24. Also, two independent conductive patterns 20 may be formed on either the first surface 6A or the second surface 6B of the circuit board 4, and each may be connected to the split connection layer 24 and the second split connection layer 26.

[0083] One circuit board 4A having the convex through-holes 10R formed with the split connection layers 24 and 26 is inserted into the internal space of the other circuit board 4B having the convex through-holes 10R formed with the split connection layers 24 and 26. Then, as shown in FIG. 6B, the insertion-side outer surface 12A(4A) and the inserted-side inner surface 12B(4B) formed with the split connection layers 24 and 26 are in surface contact in a crimped state. At this time, the outer surface-side connection layer 24A(4A) of the split connection layer 24 formed on the insertion-side outer surface 12A(4A) and the inner surface-side connection layer 24B(4B) of the split connection layer 24 formed on the inserted-side inner surface 12B(4B) are arranged at the same position in the circumferential direction. Similarly, the outer surface-side connection layer 26A(4A) of the split connection layer 26 formed on the insertion-side outer surface 12A(4A) and the inner surface-side connection layer 26B(4B) of the split connection layer 26 formed on the inserted-side inner surface 12B(4B) are arranged at the same position in the circumferential direction.

[0084] By joining the split connection layers 24 formed on one circuit board 4A and the other circuit board 4B, the conductive patterns 20 formed on the circuit boards 4A and 4B can be electrically connected, and by joining the split connection layers 26 formed on one circuit board 4A and the other circuit board 4B, the conductive patterns 20 formed on the circuit boards 4A and 4B can be electrically connected. At this time, the split connection layer 24 and the split connection layer 26 are insulated from each other.

[0085] (Connection of Conductive Patterns Formed on Circuit Boards) Next, with reference to FIGS. 7A and 7B, an aspect in which the conductive pattern 20 of one circuit board 4A and the conductive pattern 20 of the other circuit board 4B are electrically connected by fitting the convex through hole 10R according to the second embodiment will be described. FIGS. 7A and 7B are diagrams schematically showing an example in which the conductive pattern of one circuit board and the conductive pattern of the other circuit board are electrically connected in a structure in which circuit boards having convex through holes according to the second embodiment are laminated. FIG. 7A shows a first example, and FIG. 7B shows a second example.

[0086] <First example> In the first example shown in FIG. 7A, by joining the divided connection layers 24 to each other, the conductive pattern 20 formed on the first surface 6A of one circuit board 4A on the insertion side and the conductive pattern 20 formed on the first surface 6A of the other circuit board 4B on the inserted side are electrically connected, and by joining the divided connection layers 26 to each other, the conductive pattern 20 formed on the second surface 6B of one circuit board 4A and the conductive pattern 20 formed on the second surface 6B of the other circuit board 4B are electrically connected, and a structure 2 is obtained.

[0087] <Second example> In the second example shown in FIG. 7B, by joining the divided connection layers 24 to each other, the conductive pattern 20 formed on the first surface 6A of one circuit board 4A on the insertion side and the conductive pattern 20 formed on the second surface 6B of the other circuit board 4B on the inserted side are electrically connected, and by joining the divided connection layers 26 to each other, the conductive pattern 20 formed on the second surface 6B of one circuit board 4A and the conductive pattern 20 formed on the first surface 6A of the other circuit board 4B are electrically connected, and a structure 2 is obtained.

[0088] As shown in FIGS. 1A and 1B, when a plurality of convex through-holes 10P, 10Q, 10R are arranged at asymmetric positions in a plan view, one circuit board 4A and the other circuit board 4B are engaged with each other only at one relative position among the plurality of convex through-holes 10P, 10Q, 10R. For this reason, in the fitting of the convex through-hole 10R, the divided connection layers 24, 26 of the fitted convex through-hole 10R are always arranged at the same positions in the circumferential direction.

[0089] On the other hand, when only one convex through-hole 10R is provided, or when a plurality of convex through-holes 10P, 10Q, 10R are arranged at, for example, point-symmetric positions, the convex through-hole 10R can be engaged with the other circuit board 4B in a state where one circuit board 4A and the other circuit board 4B are arranged at relatively different rotational positions. In that case, for example, the divided connection layer 24 of one circuit board 4A and the divided connection layer 26 of the other circuit board 4B can be joined, and the divided connection layer 26 of one circuit board 4A and the divided connection layer 24 of the other circuit board 4B can also be joined.

[0090] Also, in the illustrated example, there are two divided connection layers 24, 26 that are divided in the circumferential direction, but there may be a case where they are divided into three or more in the circumferential direction and have three or more divided connection layers. Each divided connection layer may be equally divided or may be divided so as to have different central angles. For example, in the case of having four divided connection layers divided in the circumferential direction, a structure in which two conductive patterns 20 are formed on each of the first surface 6A and the second surface 6B, and each conductive pattern 20 is connected to a different divided connection layer is also conceivable.

[0091] As described above, in the convex through-hole 10R according to the second embodiment of the present invention, the connection layer is composed of a plurality of divided connection layers 24, 26 that are divided in the circumferential direction and insulated from each other, and when the insertion-side outer surface 12A and the inserted-side inner surface 12B on which the divided connection layers 24, 26 are formed are in surface contact in a pressure-bonded state, the divided connection layers 24, 26 formed on the insertion-side outer surface 12A and the inserted-side inner surface 12B are arranged at the same positions in the circumferential direction.

[0092] As a result, the split connection layers 24 and 26 electrically connect the conductive patterns 20 formed on one circuit board 4A and the other circuit board 4B, and a structure 2 having various circuit patterns can be obtained.

[0093] In particular, the conductive pattern 20 formed on the first surface 6A of the circuit board 4 is connected to one split connection layer 24 (26), and the conductive pattern 20 formed on the second surface 6B is connected to the other split connection layer 26 (24), whereby a structure 2 having a variety-rich circuit pattern can be realized.

[0094] As described above, when a plurality of convex through-holes 10P, 10Q, 10R are formed in one circuit board 4, a structure 2 in which various conductive patterns are connected between the circuit boards 4 can be realized by the connection layer 22 or the split connection layers 24 and 26.

[0095] (Connecting member) As described above, by fitting the convex through-hole 10 formed in the circuit board 4, one circuit board 4A and the other circuit board 4B can be surely electrically and mechanically connected without using other members. However, in the following embodiment described with reference to FIG. 8, by using a connecting member, the connection between one circuit board 4A and the other circuit board 4B can be further strengthened. FIG. 8 is a side cross-sectional view schematically showing a structure in which an end portion of one circuit board and an end portion of the other circuit board are connected by a connecting member.

[0096] In the embodiment shown in FIG. 8, there are two connecting portions 30 that connect both ends of the substrate body 6 of one circuit board 4A and both ends of the substrate body 6 of the other circuit board 4B. The connecting portion 30 can be formed of a resin material or a metal material, and preferably has a U-shaped cross-sectional shape on the side. With such a structure, the first surface 6A of one circuit board 4A and the second surface 6B of the other circuit board 4B are constrained from the outside so that the distance between one circuit board 4A and the other circuit board 4B becomes the distance CE. This distance CE is preferably set to be smaller than the distance CB between one circuit board 4A and the other circuit board 4B at the position of the fitted convex through hole 10.

[0097] In addition, when the circuit board 4A and the other circuit board 4B have a flat plate shape, the distance between one circuit board 4A and the other circuit board 4B can also be referred to as the distance between the first surface 6A of one circuit board 4A and the second surface 6B of the other circuit board 4B.

[0098] As a result, a bending moment may occur in the substrate bodies 6 of one circuit board 4A and the other circuit board 4B. In this case, a force is applied to narrow the distance CB between the first surface 6A of one circuit board 4A and the second surface 6B of the other circuit board 4B at the position of the fitted convex through hole 10. Due to this force, the fitting between the convex through hole 10 of one circuit board 4A and the convex through hole 10 of the other circuit board 4B can be further strengthened.

[0099] In addition, the number of the connecting portions 30 attached to the circuit board 4A and the other circuit board 4B is not limited to 2, and any number of three or more connecting portions 30 can be arranged. Furthermore, the structure of the connecting portion 30 is not limited to the one shown in the figure. Any other structure can be adopted as long as it can constrain one circuit board 4A and the other circuit board 4B and define the distance CB between one circuit board 4A and the other circuit board 4B.

[0100] As described above, in the present embodiment, it is preferable to provide two or more connecting portions 30 that connect the end portion of the substrate body 6 of one circuit board 4A and the end portion of the substrate body 6 of the other circuit board 4B, and the distance CE between the one circuit board 4A and the other circuit board 4B at the position of the connecting portion 30 is shorter than the distance CB between the one circuit board 4A and the other circuit board 4B at the position of the fitted convex through hole 10.

[0101] Thereby, by using the bending moments generated in the one circuit board 4A and the other circuit board 4B, the fitting between the convex through hole 10 of the one circuit board 4A and the convex through hole 10 of the other circuit board 4B can be effectively strengthened.

[0102] In the above description, the connecting portion 30 is applied to the circuit board 4 having a flat plate shape, but it is not limited thereto. It is possible to apply the connecting portion to circuit boards having other three-dimensional shapes, and the distance CE between the two circuit boards at the position of the connecting portion can be made shorter than the distance CB between the two circuit boards at the position of the fitted convex through hole 10.

[0103] (Structure in which three or more circuit boards are stacked) In the above embodiment, basically, the structure 2 in which two circuit boards 4A and 4B are stacked is shown, but it is not limited thereto. It is also possible to realize the structure 2 in which two circuit boards 4 of any number of three or more are stacked. FIG. 9 is a side cross-sectional view schematically showing an example of a structure having a conductive pattern in which three or more circuit boards are connected by convex through holes.

[0104] In FIG. 9, a structure 2 in which four circuit boards 4 are stacked is illustrated by fitting the convex through holes 10. It can be connected only by fitting the convex through holes 10, and the distance between the circuit boards 4 to be stacked can be shortened to obtain a compact structure 2. Thus, a compact structure 2 having various circuit patterns can be realized by a stacked structure in which three or more circuit boards 4 are connected by convex through holes 10.

[0105] For example, the convex through-hole 10 of the circuit board 4 laminated at the intermediate position has a plurality of divided connection layers, and some of the divided connection layers are not connected to the conductive pattern 20 formed on this circuit board 4. They may function to electrically connect the divided connection layer of the convex through-hole 10 of another circuit board 4 connected to the first surface 6A side and the divided connection layer of the convex through-hole 10 of another circuit board 4 connected to the second surface 6B side. In that case, for example, the conductive pattern of the lowermost circuit board 4 and the conductive pattern of the uppermost circuit board 4 of the structure 2 shown in FIG. 9 may be electrically connected through a divided connection layer connected in multiple stages without being connected to other conductive patterns.

[0106] (Structure with circuit boards having a three-dimensional shape laminated) In the above embodiment, the structure 2 in which the flat circuit boards 4A and 4B are laminated is shown, but it is not limited thereto. A structure 2 in which circuit boards having a three-dimensional shape as shown in FIG. 10 are laminated can also be formed. FIG. 10 is a side cross-sectional view schematically showing an example of a structure having a conductive pattern in which circuit boards having a three-dimensional shape are connected by convex through-holes. In FIG. 10, a structure 2 in which three circuit boards 4 having a three-dimensional shape are laminated is illustrated by fitting the convex through-holes 10.

[0107] A circuit board having a three-dimensional shape is also referred to as an MID (Molded Interconnect Device). The substrate body 6 of the circuit board 4 having a three-dimensional shape is preferably made of a resin molded product. As the resin material used for the resin molded product, engineering plastics can be used. As the engineering plastics, those having excellent heat resistance are preferable. For example, fluororesin, polycarbonate, polyacetal, polyamide, polyphenylene ether, amorphous polyarylate, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyimide, polyetherimide, and liquid crystal polymer can be used.

[0108] In the circuit board 4 having a three-dimensional shape, for example, a non-conductive metal complex is dispersed in the molding resin which is the material of the substrate body 6, and after molding a three-dimensional substrate using this molding resin, a laser beam is irradiated in accordance with the circuit pattern to generate metal nuclei, and then plating is performed to form a circuit.

[0109] As described above, when the circuit board 4 is a MID having a three-dimensional shape, by laminating the circuit board 4 which is a MID, a compact structure 2 rich in variations that can be used for various applications can be realized.

[0110] As described above, the structure 2 having the conductive pattern 20 according to the above-described embodiment of the present invention includes a substrate body 6 having a region formed of a planar member having a predetermined thickness and having a first surface 6A and a second surface 6B which is the back surface thereof, a frustum-shaped outer surface 12A and upper surface 14A formed of a planar member and having the first surface 6A convex, and a frustum-shaped inner surface 12B and ceiling surface 14B formed of a planar member and having the second surface 6B concave, a convex through hole 10 having an opening 16 penetrating between the upper surface 14A and the ceiling surface 14B, a connection layer 22 configured such that a conductive layer 22A formed on the outer surface 12A and upper surface 14A of the convex through hole 10 and a conductive layer 22B formed on the inner surface 12B and ceiling surface 14B are connected by a conductive layer 2C formed in the opening 16, and a conductive pattern 20 formed on at least one of the first surface 6A and the second surface 6B and connected to the connection layer 22. The circuit board 4 includes two or more of them, and an insertion-side outer surface 12A(4A) which is the outer surface 12A of the convex through hole 10 of one circuit board 4A and an inserted-side inner surface 12B(4B) which is the inner surface 12B of the convex through hole 10 of the other circuit board 4B have the same taper angle θ, the insertion-side outer surface 12A(4A) is inserted into an internal space SB surrounded by the inserted-side inner surface 12B(4B), and the insertion-side outer surface 12A(4A) and the inserted-side inner surface 12B(4B) on which the connection layer 22 is formed are in surface contact in a crimped state and have a fitting structure.

[0111] In the structure 2 as described above, since the outer insertion-side surface 12A (4A) and the inner insertion-side surface 12B (4B) of the frustum-shaped convex through-hole 10 have the same taper angle θ, the outer insertion-side surface 12A (4A) and the inner insertion-side surface 12B (4B) on which the connection layer 22 is formed can be brought into surface contact in a crimped state. Therefore, the circuit boards 4A and 4B can be connected only by fitting the convex through-hole 10, and the distance between the circuit boards 4A and 4B to be laminated can be shortened to obtain a compact structure 2. As a result, it is possible to provide a space-saving structure 2 having a conductive pattern 20 in which one circuit board 4A and the other circuit board 4B are surely electrically connected and connected with sufficient mechanical strength.

[0112] Although the embodiments and modes of implementation of the present invention have been described, the disclosed content may change in the details of the configuration, and changes in the combination and order of elements in the embodiments and modes of implementation can be realized without departing from the scope and spirit of the claimed invention.

Explanation of Reference Numerals

[0113] 2 Structure 4 Circuit board 4A One circuit board 4B The other circuit board 6 Substrate body 6A First surface 6B Second surface 10 Convex through-hole 12 Side surface portion 12A Outer surface 12B Inner surface 14 Upper surface portion 14A Upper surface 14B Ceiling surface 16 Opening 20 Conductive pattern 22 Connection layer 22A Outer surface side connection layer 22B Inner surface side connection layer 22C Conductive layer 24 Split connection layer 24A Outer surface side connection layer 24B Inner surface side connection layer 24C conductive layer 26 split connection layer 26A outer surface side connection layer 26B inner surface side connection layer 26C conductive layer 30 connecting part S, SA, SB internal space

Claims

1. A substrate body having a region formed of a planar member having a predetermined thickness and having a first surface and a second surface which is the back surface thereof, a convex through hole formed of the planar member and having a frustoconical outer surface and upper surface with the first surface being convex and a frustoconical inner surface and ceiling surface with the second surface being concave, and having an opening penetrating between the upper surface and the ceiling surface, a connection layer configured such that conductive layers formed on the outer surface and the upper surface of the convex through hole and conductive layers formed on the inner surface and the ceiling surface are connected by a conductive layer formed in the opening, a conductive pattern formed on at least one of the first surface and the second surface and connected to the connection layer, comprising two or more circuit boards, wherein an insertion-side outer surface which is the outer surface of the convex through hole of one of the circuit boards and an inserted-side inner surface which is the inner surface of the convex through hole of the other circuit board have the same taper angle, the insertion-side outer surface is inserted into an internal space surrounded by the inserted-side inner surface, and the structure having a conductive pattern has a fitting structure in which the insertion-side outer surface and the inserted-side inner surface on which the connection layer is formed are in surface contact in a pressure-bonded state.

2. The taper angle is an elevation angle with respect to a virtual bottom surface of the frustoconical convex through hole, The structure according to claim 1, wherein the taper angle is in the range of 40° or more and 80° or less.

3. The structure according to claim 1, wherein an elastic modulus of the convex through hole of one of the circuit boards is different from an elastic modulus of the convex through hole of the other circuit board.

4. The structure according to claim 3, wherein an elastic modulus of the convex through hole of the other circuit board is smaller than an elastic modulus of the convex through hole of one of the circuit boards.

5. The structure according to claim 1, wherein a hardness of the convex through hole of one of the circuit boards is different from a hardness of the convex through hole of the other circuit board.

6. The structure according to claim 1, wherein a thickness of the planar member covering the internal space of the convex through hole of one of the circuit boards is different from a thickness of the planar member covering the internal space of the convex through hole of the other circuit board.

7. The inner diameter of the ceiling surface of the convex through hole of the other circuit board is smaller than the outer diameter of the upper surface of the convex through hole of one of the circuit boards, When the outer surface on the insertion side and the inner surface on the inserted side are in surface contact in a crimped state, there is a clearance between the upper surface and the ceiling surface. The structure according to claim 1, wherein the entire area of the inner surface on the inserted side on the front side in the insertion direction from the region of the clearance is in surface contact with the outer surface on the insertion side in a crimped state.

8. The one circuit board and the other circuit board have the convex through holes of the same shape. The structure according to claim 7, wherein the outer surface on the insertion side is inserted into an internal space surrounded by the inner surface on the inserted side having an inner diameter smaller than the outer diameter of the outer surface due to the thickness of the planar member.

9. The connection layer is composed of a plurality of divided connection layers that are divided in the circumferential direction and insulated from each other. The structure according to any one of claims 1 to 8, wherein when the outer surface on the insertion side and the inner surface on the inserted side on which the divided connection layer is formed are in surface contact in a crimped state, the divided connection layers formed on the outer surface on the insertion side and the inner surface on the inserted side are arranged at the same position in the circumferential direction.

10. The structure according to claim 9, wherein the conductive pattern formed on the first surface is connected to one of the divided connection layers, and the conductive pattern formed on the second surface is connected to the other divided connection layer.

11. It includes two or more connecting portions that connect the end of the substrate body of the one circuit board and the end of the substrate body of the other circuit board. The structure according to any one of claims 1 to 8, wherein the distance between the one circuit board and the other circuit board at the position of the connecting portion is shorter than the distance between the one circuit board and the other circuit board at the position of the fitted convex through hole.

12. The structure according to any one of claims 1 to 8, wherein a plurality of the convex through holes are formed in one of the circuit boards.

13. The structure according to any one of claims 1 to 8, wherein three or more of the circuit boards are connected by the convex through holes.

14. The structure according to any one of claims 1 to 8, wherein the circuit board is a three-dimensional MID (Molded Interconnect Device: molded circuit component).

15. The structure according to any one of claims 1 to 8, wherein 70% or more of the area of the outer surface on the insertion side is in surface contact with the inner surface on the inserted side in a crimped state.

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