JP7518957B1 - Structure having conductive pattern - Google Patents

Abstract

[Problem] To provide a space-saving structure having a conductive pattern in which a plurality of circuit boards are reliably electrically connected and connected with sufficient mechanical strength. [Solution] A structure (2) includes two or more circuit boards, each including a board body (6) having a first surface (6A) and a second surface (6B) which is the reverse surface of the first surface (6A), a truncated cone-shaped outer surface (12A) and a top surface (14A) with the first surface (6A) being convex, and a truncated cone-shaped inner surface (12B) and a ceiling surface (14B) with the second surface (6B) being concave, a convex through hole (10Q) having an opening (16) penetrating between the top surface (14A) and the ceiling surface (14B), a connection layer (22) connected by a conductive layer (22C) 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), and the conductive pattern (20) has a fitting structure in which the insertion-side outer surface (12A) and the inserted-side inner surface (12B) on which the connection layer (22) is formed are in surface contact in a pressure-bonded state. [Selected Figure] Figure 2B

Description

The present invention relates to a structure having a conductive pattern formed by connecting multiple circuit boards.

In circuit boards on which conductive patterns are formed, it is desirable to electrically connect multiple circuit boards to realize multifunctional circuits. However, in order to connect multiple circuit boards, complex wiring may be required. To avoid this, a structure has been proposed in which a conductive pin is pressed into a convex through hole provided in two circuit boards to connect them (see, for example, Patent Document 1).

JP 5-90747 A

However, in the structure described in Patent Document 1, since the two circuit boards are connected using pins that are separate from the circuit boards, it is difficult to connect the circuit boards with sufficient mechanical strength even if they are electrically connected. In order to connect the circuit boards with sufficient mechanical strength, an additional connecting member is also required, which makes it difficult to achieve space saving and increases manufacturing costs.
In particular, when a circuit board having a three-dimensional shape called a molded interconnect device (MID) is used, the arrangement of pins and connecting members becomes more difficult, making it difficult to obtain a compact structure that is electrically and mechanically connected with high reliability.

The object of the present invention is therefore to provide a space-saving structure having a conductive pattern in which multiple circuit boards are reliably electrically connected and connected with sufficient mechanical strength.

The present invention includes the following aspects.
[1]
a substrate body having a region formed of a planar member of a predetermined thickness having a first surface and a second surface which is an opposite surface of the first surface;
a convex through hole formed by the planar member, the first surface being a convex truncated cone-shaped outer side and top surface, the second surface being a concave truncated cone-shaped inner side and top surface, and having an opening penetrating between the top surface and the top surface;
a connection layer formed by connecting a conductive layer formed on the outer side surface and the top surface of the convex through hole and a conductive layer formed on the inner side surface and the ceiling surface of the convex through hole with a conductive layer formed on 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
an insertion-side outer side surface, which is the outer side surface of the convex through hole of one of the circuit boards, and an insertion-side inner side surface, which is the inner side 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 on which the connection layer is formed and the inserted side inner surface have a fitting structure in which they are in surface contact in a crimped state.

[2]
the taper angle is an elevation angle of the truncated cone-shaped convex through hole with respect to a virtual bottom surface,
The structure according to "1," wherein the taper angle is in the range of 40° to 80°.

[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.

[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.

[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.

[6]
The structure described in 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.

[7]
an inner diameter of the ceiling surface of the convex through hole of the other circuit board is smaller than an outer diameter of the top surface of the convex through hole of the one circuit board;
When the insertion side outer surface and the insertion side inner surface are in surface contact in a crimped state, a clearance is provided between the top surface and the ceiling surface,
A structure described in any one of [1] to [6], in which the entire area of the inserted side inner surface, which is located before the clearance area in the insertion direction, is in surface contact with the inserted side outer surface in a pressed state.

[8]
the one circuit board and the other circuit board have the convex through holes of the same shape,
The structure described in [7], wherein the insertion side outer surface is inserted into an internal space surrounded by the insertion side inner surface 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 a circumferential direction and insulated from each other,
A structure described in any of [1] to [8], wherein when the insertion side outer surface and the insertion side inner surface on which the split connection layer is formed are in surface contact in a crimped state, the split connection layers formed on the insertion side outer surface and the insertion side inner surface are arranged at the same position in the circumferential direction.

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

[11]
two or more connecting portions for connecting an end portion of the board body of the one circuit board to an end portion of the board body of the other circuit board;
The structure according to any one of [1] to [10], 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 mated convex through hole.

[12]
The structure according to any one of [1] to [11], wherein a plurality of the convex through holes are formed in one of the circuit boards.

[13]
The structure according to any one of [1] to [12], wherein three or more of the circuit boards are connected by the convex through holes.

[14]
The structure according to any one of [1] to [13], wherein the circuit board is a molded interconnect device (MID) having a three-dimensional shape.

[15]
The structure according to any one of [1] to [14], wherein 70% or more of the area of the outer surface of the insertion side is in surface contact with the inner surface of the insertion side in a crimped state.

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

FIG. 1 is a perspective view showing a schematic diagram of an example of a circuit board constituting a structure having a conductive pattern according to the present invention, the diagram showing a first surface side. FIG. 2 is a perspective view showing a schematic diagram of an example of a circuit board constituting a structure having a conductive pattern according to the present invention, illustrating the second surface side. FIG. 2 is a side cross-sectional view showing a schematic diagram of a convex through hole according to a first embodiment of the present invention, showing cross section AA of FIGS. 1A and 1B, and showing an example in which a conductive pattern is formed on the first surface. FIG. 2 is a side cross-sectional view showing a schematic diagram of a convex through hole according to the first embodiment of the present invention, showing cross section B-B of FIGS. 1A and 1B, and showing an example in which a conductive pattern is formed on the second surface. 1 is a side cross-sectional view that illustrates a structure in which a convex through-hole of one circuit board and a convex through-hole of another circuit board are fitted together; FIG. 1 is a side cross-sectional view showing a schematic structure in which a convex through hole of one circuit board is fitted into a convex through hole of another circuit board, the circuit board having the same shape of convex through holes. FIG. FIG. 1 is a diagram showing a first example of a structure having a conductive pattern in which circuit boards having convex through holes according to the first embodiment are stacked, in which the conductive pattern of one circuit board is electrically connected to the conductive pattern of the other circuit board. FIG. 13 is a diagram showing a second example of a structure having a conductive pattern in which circuit boards having convex through holes according to the first embodiment are stacked, in which the conductive pattern of one circuit board is electrically connected to the conductive pattern of the other circuit board. FIG. 13 is a diagram showing a schematic diagram of a third example of a structure having a conductive pattern in which circuit boards having convex through holes according to the first embodiment are stacked, in which the conductive pattern of one circuit board is electrically connected to the conductive pattern of the other circuit board. FIG. 13 is a schematic diagram showing a fourth example of a structure having a conductive pattern in which circuit boards having convex through holes according to the first embodiment are stacked, in which the conductive pattern of one circuit board is electrically connected to the conductive pattern of the other circuit board. FIG. 5 is a diagram showing a schematic diagram of a fifth example of a structure having a conductive pattern in which circuit boards having convex through holes according to the first embodiment are stacked, in which the conductive pattern of one circuit board is electrically connected to the conductive pattern of the other circuit board. FIG. 2 is a side cross-sectional view showing a schematic diagram of a convex through hole according to a second embodiment of the present invention, showing cross section CC of FIGS. 1A and 1B, and showing an example in which a conductive pattern is formed on the first and second surfaces. 6B is a plan cross-sectional view showing a state in which a convex through hole of one circuit board having a convex through hole of a second embodiment is mated with a convex through hole of another circuit board, the plan cross-sectional view showing the mated state from the position of cross-section D-D in FIG. FIG. 13 is a diagram showing a first example of a structure having a conductive pattern in which circuit boards having convex through holes according to a second embodiment are stacked, in which the conductive pattern of one circuit board is electrically connected to the conductive pattern of the other circuit board. FIG. 13 is a schematic diagram showing a second example of a structure having a conductive pattern in which circuit boards having convex through holes according to the second embodiment are stacked, in which the conductive pattern of one circuit board is electrically connected to the conductive pattern of the other circuit board. 1 is a side cross-sectional view that illustrates a structure in which an end portion of one circuit board and an end portion of another circuit board are connected by a connecting member. FIG. 1 is a side cross-sectional view that shows a schematic example of a structure having a conductive pattern in which three or more circuit boards are connected by convex through holes. FIG. 1 is a side cross-sectional view that shows a schematic example of a structure having a conductive pattern in which a circuit board having a three-dimensional shape is connected by a convex through-hole.

Below, with reference to the drawings, an embodiment for carrying out the present invention will be described. In each drawing, corresponding components having the same function are given the same reference numerals. For convenience, the embodiments may be shown separately in consideration of ease of explanation or understanding of the main points, but partial substitution or combination of configurations shown in different embodiments is possible. In the embodiments described below, descriptions of matters common to the above-mentioned embodiments will be omitted, and only the differences will be described. In particular, similar effects due to similar configurations will not be mentioned in each embodiment. The sizes and positional relationships of components shown in the drawings may be exaggerated in order to clarify the explanation.

(Circuit board)
In the present invention, a structure having a conductive pattern is formed by stacking a plurality of circuit boards. The stacked circuit boards have a board body having a flat plate shape or any other three-dimensional shape. The board body can be manufactured by molding, but can also be manufactured by laser processing or the like from a material of a certain shape.

First, an overview of a circuit board constituting a structure having a conductive pattern will be described with reference to Figures 1A and 1B. In the following, a description will be given taking a board body having a flat plate shape as an example. Figures 1A and 1B are perspective views showing an example of a circuit board constituting a structure having a conductive pattern according to the present invention, with Figure 1A showing the first surface side and Figure 1B showing the second surface side. The second surface is the reverse side of the first surface, and the circuit board is rotated 180 degrees in the direction shown by the arrow in Figure 1A to reach the state shown in Figure 1B.

The circuit board 4 shown in Figures 1A and 1B has a board body 6 formed of a planar member of a predetermined thickness having a first surface 6A and a second surface 6B on the reverse side of the first surface. A planar member has a non-blocky shape in which the distance (thickness) between the first surface and the second surface on the reverse side of the first surface is smaller than the size of the first surface and the second surface on the reverse side of the first surface. The first surface 6A and the second surface 6B on the reverse side of the first surface may not only be flat, but may also have any curved surface, uneven surface, bent portion, etc. The predetermined thickness of the planar member is not limited to a constant thickness, and may vary depending on the region.

The substrate body 6 described below has a flat plate shape with all areas formed of planar members, but is not limited to this. A substrate body having any other three-dimensional shape, including a block-shaped area, can be used as long as it has planar members at least in the area where the convex through holes 10 described below are arranged.

The substrate body 6 has a convex through hole 10 integrally formed by a planar member. 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, a convex through hole is a general term for a structure that electrically connects conductive patterns formed on both sides of a circuit board, or conductive patterns of multiple stacked circuit boards, by a conductive part formed in an opening. Multiple circuit boards 4 can be electrically and mechanically connected via the convex through holes 10 that are conductive to the conductive patterns.

As the material for the substrate body 6, inorganic and organic materials can be used. Examples of inorganic materials include ceramics, and examples of organic materials include resins. As ceramics, silicon nitride sintered bodies, sialon sintered bodies, silicon carbide sintered bodies, alumina sintered bodies, aluminum nitride sintered bodies, etc. can be suitably used. In addition to these ceramics, metals that have been molded and have their surfaces insulated can also be used.

As the resin, a thermosetting resin or a thermoplastic resin can be suitably used. Examples of the thermosetting resin include epoxy resin, melamine resin, phenol resin, urea resin, and unsaturated polyester resin. Examples of the thermoplastic resin include polyethylene, polypropylene, polystyrene, ABS resin, polyvinyl chloride resin, methyl methacrylate resin, nylon, polyester resin, fluororesin, polycarbonate, polyacetal, polyamide, polyphenylene ether, amorphous polyarylate, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyimide, polyetherimide, and liquid crystal polymer.

The convex through hole 10 has a first surface 6A with a convex truncated cone-shaped outer side surface 12A and top surface 14A, and a second surface 6B with a concave truncated cone-shaped inner side surface 12B and ceiling surface 14B, and has an opening 16 that penetrates between the top surface 14A and the ceiling surface 14B. Of such convex through holes 10, different types of convex through holes 10P, 10Q, and 10R are formed in the circuit board 4 shown in Figures 1A and 1B.

The following describes each type of convex through hole 10P, 10Q, and 10R in detail. Note that for common parts of convex through holes regardless of type, such as in Figures 3, 4, and 8 to 10, the convex through hole is indicated by reference number 10, and in the explanation of each type, it is indicated by reference numbers 10P, 10Q, and 10R, respectively.

(Convex through hole according to the first embodiment)
First, a convex through hole 10 according to a first embodiment of the present invention will be described with reference to Figures 2A and 2B. Figure 2A is a side cross-sectional view showing a schematic view of a convex through hole according to a first embodiment of the present invention, showing the cross section A-A in Figures 1A and 1B, and showing an example in which a conductive pattern is formed on the first surface. Figure 2B is a side cross-sectional view showing a schematic view of a convex through hole according to a first embodiment of the present invention, showing the cross section B-B in Figures 1A and 1B, and showing an example in which a conductive pattern is formed on the second surface. In both figures, the thicknesses of the connection layer and the conductive pattern are shown thicker than they actually are.

The convex through holes 10P, 10Q according to the first embodiment are integrally molded from the same material as the substrate body 6. However, this is not limited to this, and they can also be molded from a material different from that of the substrate body 6 by two-color molding or the like. The convex through holes 10P, 10Q are formed with a planar member to have a side portion 12 constituting the side of the truncated cone and an upper surface portion 14 constituting the upper surface of the truncated cone. In the convex through holes 10P, 10Q, the side portion 12 is formed to have a taper angle of angle θ. Here, the taper angle θ is the elevation angle with respect to the imaginary bottom surface of the convex through hole 10 in the shape of a truncated cone. Note that the taper angle is indicated by the angle between the imaginary bottom surface of the imaginary cone formed by extending the outer side surface of the convex through hole 10 and the center line of the cone perpendicular to the imaginary cone. In this case, the angle is 90°-θ.

The upper surface portion 14 of the convex through holes 10P, 10Q has an opening 16 which is a through hole. The bottom surface of the truncated cone is open, forming an internal space S. The outer surfaces of the convex through holes 10P, 10Q are composed of an outer surface 12A formed by the side surface portion 12 and an upper surface 14A formed by the upper surface portion 14. On the other hand, the inner surfaces of the convex through holes 10P, 10Q are composed of an inner surface 12B formed by the side surface portion 12 and a ceiling surface 14B formed by the upper surface portion 14. In other words, the internal space S is formed by being surrounded by the inner surface 12B and the ceiling surface 14B.

A conductive connection layer 22 is formed in the convex through holes 10P, 10Q. 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, 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.

In the convex through hole 10P, the 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, the 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 either conductive pattern 20, not only the circuit pattern but also electronic components electrically connected to the circuit pattern may be attached. Note that the conductive pattern 20 may be formed on both the first surface 6A and the second surface 6B of the substrate body 6, and the conductive patterns 20 on both sides may be connected by the connection layer 22.

The conductive pattern 20 and the connection layer 22 can be formed from 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), and ruthenium (Ru), and are preferably copper-plated.

The thickness of the substrate body 6 can be in the range of 0.2 mm to 5.0 mm. The thickness of the side portion 12 and the top portion 14 of the convex through holes 10P, 10Q can be in the range of 0.2 mm to 5.0 mm. The thickness of the top portion 14 of the convex through holes 10P, 10Q can be the same as or different from the thickness of the side portion 12. The thickness of the side portion 12 and the top portion 14 of the convex through holes 10P, 10Q can be the same as or different from the thickness of the substrate body 6. The outer diameter of the top portion 14 of the truncated convex through holes 10P, 10Q can be in the range of 0.2 mm to 10.0 mm, and the height can be in the range of 0.2 mm to 10.0 mm.

(Engagement structure of convex through hole)
Next, the fitting structure of the convex through-hole 10 will be described with reference to Fig. 3. Fig. 3 is a side cross-sectional view showing a structure in which a convex through-hole of one circuit board and a convex through-hole of the other circuit board are fitted together. The thickness of the connection layer formed on the outer surface of the convex through-hole 10 is very thin, so it is omitted in the drawing. In Fig. 3, one circuit board 4A is shown in a light color rather than hatched in order to clearly show the arrows and the like.

Figure 3 shows a part of a 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 outer side of the convex through hole 10 of one circuit board 4A, which is the insertion side outer surface 12A (4A), is inserted into an internal space SB surrounded by the inner side of the convex through hole 10 of the other circuit board 4B, which is the insertion side inner surface 12B (4B). The shapes of the convex through hole 10 of one circuit board 4A and the convex through hole 10 of the other circuit board 4B may be the same or different. Note that Figure 3 shows a case where the shapes of the convex through holes 10 are different. In either case, the insertion side outer surface 12A (4A) of one circuit board 4A and the insertion side inner surface 12B (4B) of the other circuit board 4B have the same taper angle θ.

Furthermore, in this 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 top surface 14A of the convex through hole 10 of the inserted circuit board 4A. In other words, the inner diameter D2 (4B) of the end of the back side in the insertion direction of the inserted side inner surface 12B (4B) is smaller than the outer diameter D1 (4A) of the end of the back side in the insertion direction of the inserted side outer surface 12A (4A). As a result, even if the convex through hole 10 of one circuit board 4A is pushed all the way into the internal space SB, a predetermined clearance CT can be secured between the top 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.

Since the inserting side outer surface 12A (4A) and the inserted side inner surface 12B (4B) have the same taper angle θ, when the convex through hole 10 of one circuit board 4A is pushed all the way into the internal space SB, the entire area of the inserted side inner surface 12B (4B) on the front side in the insertion direction of the clearance CT area comes into surface contact with the inserting side outer surface 12A (4A) in a crimped state.

In other words, when the insertion-side outer surface 12A (4A) of one circuit board 4A is inserted toward the back of the space SB surrounded by the insertion-side inner surface 12B (4B) of the other circuit board 4B, the inner diameter id (h) of the insertion-side inner surface 12B (4B) corresponding to position h in the insertion direction (h = 0 at the insertion opening) becomes smaller along the taper, and when the inner diameter id (h) of the insertion-side inner surface 12B (4B) matches the outer diameter D1 (4A) of the upper surface 14A of the insertion-side outer surface 12A (4A), it becomes impossible to insert any further. At this time, a clearance CT is generated between the top 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 an interlocking structure can be obtained in which the inserting side outer surface 12A (4A) on which the connection layer 22 is formed and the inserted side inner surface 12B (4B) are in surface contact in a crimped state over the entire area where the inserting side outer surface 12A (4A) is inserted into the internal space SB.

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 together, an efficient connection with low electrical contact resistance can be achieved, and additional work such as soldering is not required. Therefore, one circuit board 4A and the other circuit board 4B can be connected at a short distance, so a compact structure 2 can be realized.

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 top surface 14A of the convex through hole 10 of one circuit board 4A, and when the insertion side outer surface 12A (4A) and the inserted side inner surface 12B (4B) are in surface contact in a crimped state, there is a clearance CT between the top surface 14A (4A) and the ceiling surface 14B (4B), and the entire area of the inserted side inner surface 12B (4B) on the near side in the insertion direction before the area of the clearance CT is in surface contact with the insertion side outer surface 12A (4A) in a crimped state.

This allows one circuit board 4A and the other circuit board 4B to be reliably electrically connected and to obtain a mating structure in which they are connected with sufficient mechanical strength. Taking into account the manufacturing tolerance of the convex through hole 10, it is preferable to make the clearance CT small within a range in which the insert side outer surface 12A (4A) and the inserted side inner surface 12B (4B) are reliably in surface contact in a crimped state. Taking into account the elastic deformation of the convex through hole 10, there may be cases in which there is no clearance and the top 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 are in contact with each other when the insert side outer surface 12A (4A) and the inserted side inner surface 12B (4B) are in surface contact in a crimped state. In this case, the conductive layer 22C formed on the top 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 in electrical contact, and a more efficient electrical connection can be expected.

<Taper angle>
When the insertion side outer surface 12A (4A) of the circuit board 4A is pressed into the inner side of the internal space SB to press against the inserted side inner surface 12B (4B) of the other circuit board 4B, a wedge effect occurs due to the taper angle θ. If the force pressing the insertion side outer surface 12A (4A) into the inner side of the internal space SB is F, and the wedge effect force (full-circumference force) 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)
In the above equation, 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 greater the surface pressure between the insertion side outer surface 12A (4A) and the inserted side inner surface 12B (4B).

On the other hand, if the specified clearance is CT, then
D1 (4A) = D2 (4B) + 2 x CT/Tan (θ)
Since the following relationship exists:
CT=(D1(4A)-D2(4B))×Tan(θ)/2
D1 (4A) > D2 (4B)
It becomes.

In addition, if the change in the inner diameter of the inner surface 12B is ΔD and the position change in the insertion direction (position change in the direction perpendicular to the imaginary bottom surface of the truncated cone) accompanying the change in the inner diameter ΔD is Δh, then similarly to the case of the clearance CT,
Δh=ΔD×Tan(θ)/2
It becomes.

As the taper angle θ increases (approaching 90°), the value of Tan(θ) increases, and the clearance CT increases. In addition, the change in the inner diameter ΔD of the inserted inner surface 12B (4B) increases the position change Δh in the insertion direction. Considering the tolerance of the resin molded body, when the taper angle θ is large, variation is likely to occur in the position in the insertion direction where the inner diameter of the inserted inner surface 12B (4B) matches the outer diameter D1 (4A) of the upper surface 12A of the inserted outer surface 12A (4A).

For this reason, for example, when fitting a circuit board 4 having multiple convex through holes 10, there is a risk that the distance between one circuit board 4A and the other circuit board 4B will differ depending on each of the convex through holes 10. In that case, there is a risk that bending will occur in the circuit board 4, and one circuit board 4A and the other circuit board 4B will not be properly connected.

Considering these conflicting factors, it can be said that the taper angle θ is preferably in the range of 40° to 80°, and more preferably in the range of 50° to 70°. By having the convex through hole 10 have a taper angle θ in this range, it is possible to achieve strong surface contact between the insertion side outer surface 12A (4A) and the inserted side inner surface 12B (4B) due to a wedge effect, and it is possible to suppress the variation in the distance between the one circuit board 4A and the other circuit board 4B into which the convex through hole 10 is fitted.

With the above-mentioned structure, it is preferable that 70% or more of the area of the insertion side outer surface 12A (4A) is in surface contact with the insertion side inner surface 12B (4B) in a crimped state, and it is even more preferable that 80% or more of the area is in surface contact with the insertion side inner surface 12B (4B) in a crimped state. This allows the circuit board 4A and the other circuit board 4B to be firmly connected, and the distance between the circuit boards is reduced to obtain a compact laminated structure.

<Elasticity Modulus of Convex Through Hole>
In a fitting structure in which the inserting side outer surface 12A (4A) and the inserted side inner surface 12B (4B) are in surface contact in a crimped state, it is considered that the mating convex through-hole 10 elastically deforms within a small 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. As a result, when the convex through-holes 10 are fitted together, the convex through-hole 10 with the lower elastic modulus mainly elastically deforms, and a stable fitting structure is obtained.

Specific values for the elastic modulus include, for example, one of the tensile elastic modulus being approximately 2000 to 25000 MPa, and the other being approximately 1600 to 22000 MPa. However, this is not limiting, and any other elastic modulus can be used.

In this way, 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 brought into surface contact in a crimped state.

Because the elastic deformation is slight, the elastic modulus of either of the mating convex through holes 10 can be smaller. However, deformation in the expanding direction is generally expected to result in more uniform deformation without buckling, etc., compared to deformation in the contracting direction. From this perspective, it is more preferable that the elastic modulus of the convex through hole 10 of the other circuit board 4B, where elastic deformation in the expanding direction occurs, is smaller than the elastic modulus of the convex through hole 10 of one circuit board 4A. This allows more uniform elastic deformation to occur in the mating convex through holes 10, resulting in a fitting structure that provides more stable surface contact in a crimped state.

<Hardness of convex through-hole>
By making the hardness of the mating convex through-holes 10 different, the same effect as when the elastic modulus is different can be obtained. It is preferable that the hardness of the convex through-holes 10 of one circuit board 4A is different from the hardness of the convex through-holes 10 of the other circuit board 4B. For example, the tensile elastic modulus of one of them is about Rockwell R65 to 100, and the tensile elastic modulus of the other is about Rockwell R80 to 130. However, this is not limited to this, and resin materials of any other hardness can be used.

In this way, 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.

As with the elastic modulus, it is more preferable that the hardness of the convex through hole 10 of the other circuit board 4B, where elastic deformation in the expanding direction occurs, is lower than the hardness of the convex through hole 10 of the one circuit board 4A.

<Thickness of Planar Member Covering Internal Space of Convex Through Hole>
Furthermore, the same effect as in the case where the elastic moduli are different can be obtained by making the thickness of the planar member covering the internal space SA of the convex through hole 10 of one circuit board 4A 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.

In this way, 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.

Furthermore, as in the case of the elastic modulus, 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 in the expanding direction occurs, 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.

(Interlocking structure of convex through holes of the same shape)
Next, a structure in which circuit boards 4 are connected by fitting convex through holes 10 of the same shape will be described with reference to Fig. 4. Fig. 4 is a side cross-sectional view that shows a schematic structure in which a convex through hole of one circuit board is fitted to a convex through hole of another circuit board, the convex through hole having the same shape.

Figure 4 also shows a portion of a structure 2 having a conductive pattern formed by connecting one circuit board 4A and the other circuit board 4B by engaging a convex through hole 10. In Figure 4, convex through holes 10 of the same shape are engaged to connect the circuit boards 4A and 4B. Therefore, the inner diameter of the inner surface 12B of the convex through hole 10 is made smaller than the outer diameter of the outer surface 12A due to the thickness t of the planar member covering the internal space S. Therefore, when convex through holes 10 of the same shape are engaged with each other, it is believed that a predetermined clearance CT can be obtained.

To explain this in more detail, 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 top 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 top portion 14 of the convex through hole 10 is t, the following relationship is satisfied.
D2 (4B) = D1 (4A) + 2 x t/Tan - 2 x t/Sin (θ)

In order to have clearance CT, the relationship D2 (4B) < D1 (4A) must be satisfied.
D1(4A)+2×t/Tan-2×t/Sin(θ)<D1(4A)
The above formula can be rearranged to obtain the following relationship:
Cos(θ)<1
Since the taper angle θ is never 90°, when convex through holes 10 of the same shape are fitted together, a predetermined clearance CT can always be maintained. As described above, there may be cases where the clearance CT is not maintained, but when the clearance CT is maintained, unintended conduction (short circuit) between circuits can be suppressed, which is particularly effective when there is no solder resist.

In this way, when one circuit board 4A and the other circuit board 4B have the same shaped convex through hole 10, the insertion side outer surface 12A (4A) is inserted into the internal space SB surrounded by the insertion side inner surface 12B (4B) whose inner diameter is smaller than the outer diameter of the outer surface 12A (4B) due to the thickness t of the planar member.

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 secured, and the entire area of the inserted side inner surface 12B (4B) on the front side in the insertion direction of the area of the clearance CT can be reliably brought into surface contact with the inserted side outer surface 12A (4A) in a crimped state.

The thickness of the top surface portion 14 of the convex through hole 10 may be slightly thicker than the thickness of the side surface portion 12, but from the viewpoint of forming the opening 16, which is a through hole, it is unlikely that the top surface portion 14 would be significantly thicker. If the taper angle θ is in the range of 40° to 80°, the relationship D2 (4B) < D1 (4A) is always considered to be satisfied. Note that the fitting structure described with reference to Figures 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 hole 10 according to all of the embodiments described below.

(Connection of conductive patterns formed on a circuit board)
Next, various aspects 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 with reference to Figures 5A to 5E. Figures 5A to 5E are diagrams that show 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 conductive pattern in which circuit boards having convex through holes according to the first embodiment are stacked, with Figure 5A showing a first example, Figure 5B showing a second example, Figure 5C showing a third example, Figure 5D showing a fourth example, and Figure 5E showing a fifth example.

<First Example>
In the first example shown in Fig. 5A, both the circuit board 4A on the inserting side and the other circuit board 4B on the receiving side have convex through holes 10P with conductive patterns 20 formed on the first surfaces 6A as shown in Fig. 2A. This provides a structure 2 in which the conductive pattern 20 formed on the first surface 6A of the one circuit board 4A and the conductive pattern 20 formed on the first surface 6A of the other circuit board 4B are electrically connected.

<Second Example>
In the second example shown in Fig. 5B, both the circuit board 4A on the inserting side and the circuit board 4B on the receiving side have the convex through hole 10Q with the conductive pattern 20 formed on the second surface 6B as shown in Fig. 2B. This provides a structure 2 in which the conductive pattern 20 formed on the second surface 6B of the circuit board 4A on one side and the conductive pattern 20 formed on the second surface 6B of the circuit board 4B on the other side are electrically connected.

<Third Example>
In the third example shown in Fig. 5C, one circuit board 4A on the insertion side has a convex through hole 10Q on 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 on which a conductive pattern 20 is formed on the first surface 6A as shown in Fig. 2A. This results in 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 first surface 6A of the other circuit board 4B are electrically connected.

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

<Fifth Example>
5E, the 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 connected by a connection layer 22, and the 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 connected by a connection layer 22. Thus, a structure 2 is obtained in which the conductive patterns 20 formed on both surfaces of the one circuit board 4A and the other circuit board 4B are electrically connected by the mated convex through holes 10.

As described above, the convex through hole 10 according to the first embodiment of the present invention makes it possible to obtain a structure 2 having various circuit patterns.

(Convex through hole according to the second embodiment)
Next, a convex through hole according to a second embodiment of the present invention will be described with reference to Figures 6A and 6B. Figure 6A is a side cross-sectional view showing a convex through hole according to a second embodiment of the present invention, showing the cross section C-C of Figures 1A and 1B, and showing an example in which a conductive pattern is formed on the first and second surfaces. Figure 6B is a plan cross-sectional view showing a mated state from the position of the cross section D-D of Figure 6A, which shows a state in which a convex through hole of one circuit board having a convex through hole according to the second embodiment is mated with a convex through hole of the other circuit board. In both figures, the thickness of the connection layer and the conductive pattern are shown thicker than the actual thickness. In this embodiment, as long as a mating structure in which the surfaces are in surface contact in the crimped state is obtained, the clearance CT may or may not exist.

As shown in FIG. 6B, the convex through hole 10R formed in the circuit board 4 according to this embodiment is configured with two split connection layers 24, 26, each of which is divided in two in the circumferential direction and is insulated from the other. A sufficient insulating space is provided between the two split connection layers 24, 26. Furthermore, the insulating space can be filled with an insulating material.

To describe the split connection layers 24 and 26 in more detail, the split connection layer 24 on the left side of FIG. 6A and FIG. 6B is an outer surface side connection layer 24A formed on the outer surface 12A of the convex through hole 10R, an inner surface side connection layer 24B 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 formed in the opening 16. Similarly, the split connection layer 26 on the right side of FIG. 6A and FIG. 6B is an outer surface side connection layer 26A formed on the outer surface 12A of the convex through hole 10R, an inner surface side connection layer 26B 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 formed in the opening 16.

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, this is not limited to the above, and conversely, there may be cases where the conductive pattern 20 formed on the first surface 6A of the circuit board 4 is connected to the split connection layer 26, and the conductive pattern 20 formed on the second surface 6B is connected to the split connection layer 24. In addition, there may be cases where two independent conductive patterns 20 are formed on either the first surface 6A or the second surface 6B of the circuit board 4, and each is connected to the split connection layer 24 and the second split connection layer 26.

One circuit board 4A having a convex through hole 10R formed in the split connection layer 24, 26 is inserted into the internal space of the other circuit board 4B having a convex through hole 10R formed in the split connection layer 24, 26. Then, as shown in FIG. 6B, the insert side outer surface 12A (4A) and the inserted side inner surface 12B (4B) on which the split connection layer 24, 26 is formed 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 insert 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 insertion side inner surface 12B (4B) are arranged at the same position in the circumferential direction.

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

(Connection of conductive patterns formed on a circuit board)
Next, with reference to Figures 7A and 7B, a mode 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. Figures 7A and 7B are schematic diagrams showing examples in which the conductive pattern of one circuit board is electrically connected to the conductive pattern of the other circuit board in a structure having a conductive pattern in which circuit boards having convex through holes according to the second embodiment are stacked, with Figure 7A showing a first example and Figure 7B showing a second example.

<First Example>
In the first example shown in Figure 7A, the split connection layers 24 are joined together to electrically connect the conductive pattern 20 formed on the first surface 6A of one circuit board 4A on the insertion side to the conductive pattern 20 formed on the first surface 6A of the other circuit board 4B on the inserted side, and the split connection layers 26 are joined together to obtain a structure 2 in which the conductive pattern 20 formed on the second surface 6B of one circuit board 4A to the conductive pattern 20 formed on the second surface 6B of the other circuit board 4B is electrically connected.

<Second Example>
In the second example shown in Figure 7B, the split connection layers 24 are joined together to electrically connect the conductive pattern 20 formed on the first surface 6A of one circuit board 4A on the insertion side to the conductive pattern 20 formed on the second surface 6B of the other circuit board 4B on the inserted side, and the split connection layers 26 are joined together to obtain a structure 2 in which the conductive pattern 20 formed on the second surface 6B of one circuit board 4A to the conductive pattern 20 formed on the first surface 6A of the other circuit board 4B is electrically connected.

As shown in Figures 1A and 1B, when multiple convex through holes 10P, 10Q, 10R are arranged in asymmetrical positions in a plan view, multiple convex through holes 10P, 10Q, 10R of one circuit board 4A and the other circuit board 4B are fitted together at only one relative position. Therefore, when fitting the convex through holes 10R, the split connection layers 24, 26 of the fitted convex through holes 10R are always arranged at the same position in the circumferential direction.

On the other hand, when only one convex through hole 10R is provided, or when multiple convex through holes 10P, 10Q, 10R are arranged, for example, at point-symmetric positions, the convex through hole 10R can be fitted with one circuit board 4A and the other circuit board 4B arranged at relatively different rotational positions. In that case, for example, the split connection layer 24 of one circuit board 4A can be joined to the split connection layer 26 of the other circuit board 4B, and the split connection layer 26 of one circuit board 4A can be joined to the split connection layer 24 of the other circuit board 4B.

In addition, while the illustrated example has two split connection layers 24, 26 divided into two in the circumferential direction, it is also possible to have three or more split connection layers by dividing the layer into three or more in the circumferential direction. Each split connection layer may be equally divided or divided to have a different central angle. For example, in the case of having four split connection layers divided into four 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 split connection layer, is also conceivable.

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

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

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), thereby realizing a structure 2 having a wide variety of circuit patterns.

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

(Connecting member)
As described above, the engagement of the convex through holes 10 formed in the circuit boards 4 allows the one circuit board 4A and the other circuit board 4B to be reliably connected electrically and mechanically without using any other members. However, in the embodiment described below with reference to Fig. 8, the connection between the one circuit board 4A and the other circuit board 4B can be further strengthened by using a connecting member. Fig. 8 is a side cross-sectional view that typically shows a structure in which an end of the one circuit board and an end of the other circuit board are connected by a connecting member.

In the embodiment shown in FIG. 8, there are two connecting parts 30 that connect both ends of the board body 6 of one circuit board 4A to both ends of the board body 6 of the other circuit board 4B. The connecting parts 30 can be formed of a resin material or a metal material, and preferably have a U-shaped side cross-sectional shape. With this structure, the first surface 6A of the one circuit board 4A and the second surface 6B of the other circuit board 4B are restrained from the outside, so that the distance CE is set between the one circuit board 4A and the other circuit board 4B. It is preferable that this distance CE is set to be smaller than the distance CB between the one circuit board 4A and the other circuit board 4B at the position of the mated convex through hole 10.

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

This can cause bending moments in the board bodies 6 of the one circuit board 4A and the other circuit board 4B. In this case, a force is applied that narrows the distance CB between the first surface 6A of the one circuit board 4A and the second surface 6B of the other circuit board 4B at the position of the mated convex through hole 10. This force can further strengthen the mating between the convex through hole 10 of the one circuit board 4A and the convex through hole 10 of the other circuit board 4B.

The number of connecting parts 30 attached to the circuit board 4A and the other circuit board 4B is not limited to two, and any number of connecting parts 30 greater than or equal to three can be arranged. Furthermore, the structure of the connecting parts 30 is not limited to that shown in the figure. Any other structure can be adopted as long as it can restrain the one circuit board 4A and the other circuit board 4B and define the distance CB between the one circuit board 4A and the other circuit board 4B.

As described above, in this embodiment, two or more connecting portions 30 are provided that connect the end of the board body 6 of one circuit board 4A to the end of the board body 6 of the other circuit board 4B, and it is preferable that 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 mated convex through hole 10.

This allows the bending moment generated in one circuit board 4A and the other circuit board 4B to effectively strengthen the fit between the convex through hole 10 of one circuit board 4A and the convex through hole 10 of the other circuit board 4B.

In the above, the connecting portion 30 is applied to a circuit board 4 having a flat plate shape, but this is not limited to this. The connecting portion can be applied 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 shorter than the distance CB between the two circuit boards at the position of the mated convex through hole 10.

(Structure in which three or more circuit boards are stacked)
In the above embodiment, the structure 2 is basically formed by stacking two circuit boards 4A and 4B, but is not limited to this. It is also possible to realize a structure 2 in which any number of two circuit boards 4, three or more, are stacked. Fig. 9 is a side cross-sectional view that shows a schematic example of a structure having a conductive pattern in which three or more circuit boards are connected by convex through holes.

Figure 9 illustrates an example of a structure 2 in which four circuit boards 4 are stacked by engaging the convex through holes 10. Connection is possible simply by engaging the convex through holes 10, and the distance between the stacked circuit boards 4 can be shortened to obtain a compact structure 2. In this way, a stacked structure in which three or more circuit boards 4 are connected by the convex through holes 10 can realize a compact structure 2 with a variety of circuit patterns.

For example, the convex through hole 10 of the circuit board 4 stacked in the middle position may have multiple split connection layers, some of which are not connected to the conductive pattern 20 formed on this circuit board 4, and may function to electrically connect the split connection layer of the convex through hole 10 of the other circuit board 4 connected to the first surface 6A side and the split connection layer of the convex through hole 10 of the other circuit board 4 connected to the second surface 6B side. In that case, for example, the conductive pattern of the bottom circuit board 4 and the conductive pattern of the top circuit board 4 of the structure 2 shown in Figure 9 may be electrically connected through split connection layers connected in multiple stages, without being connected to other conductive patterns.

(Structure in which circuit boards having three-dimensional shapes are stacked)
In the above embodiment, the structure 2 is shown in which flat circuit boards 4A and 4B are stacked, but the present invention is not limited to this. It is also possible to form a structure 2 in which circuit boards having a three-dimensional shape are stacked as shown in Fig. 10. Fig. 10 is a side cross-sectional view that shows a schematic example of a structure having a conductive pattern in which a three-dimensional circuit board is connected by a convex through hole. Fig. 10 shows a structure 2 in which three three-dimensional circuit boards 4 are stacked by fitting the convex through holes 10.

A circuit board having a three-dimensional shape is also called a MID (molded interconnect device). The board body 6 of the circuit board 4 having a three-dimensional shape is preferably made of a resin molded product. Engineering plastics can be used as the resin material used for the resin molded product. As the engineering plastic, those with excellent heat resistance are preferable, and for example, fluororesin, polycarbonate, polyacetal, polyamide, polyphenylene ether, amorphous polyarylate, polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyimide, polyetherimide, and liquid crystal polymer can be used.

For example, in the case of a circuit board 4 having a three-dimensional shape, a non-conductive metal complex is dispersed in the molding resin that is the material of the board body 6, and after this molding resin is used to mold a three-dimensional board, a laser beam is irradiated in accordance with the circuit pattern to produce metal nuclei, and then plating is applied to form the circuit.

In this way, when the circuit board 4 is an MID having a three-dimensional shape, stacking the circuit boards 4 that are MIDs can realize a compact structure 2 with a wide variety of variations that can be used for a variety of purposes.

As described above, the structure 2 having the conductive pattern 20 according to the above embodiment of the present invention includes a substrate body 6 having an area formed of a planar member of a predetermined thickness having a first surface 6A and a second surface 6B which is the reverse surface of the first surface 6A; a convex through hole 10 formed of a planar member, the first surface 6A being a convex truncated cone-shaped outer surface 12A and upper surface 14A, and the second surface 6B being a concave truncated cone-shaped inner surface 12B and ceiling surface 14B, the opening 16 penetrating between the upper surface 14A and the ceiling surface 14B; and 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 formed in the opening 16. The circuit board 4 includes two or more circuit boards 4 each including a connection layer 22 connected by 2C 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, and the insertion side outer surface 12A (4A), which is the outer surface 12A of the convex through hole 10 of one circuit board 4A, and the insertion 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, and the insertion side outer surface 12A (4A) is inserted into the internal space SB surrounded by the insertion side inner surface 12B (4B), and the insertion side outer surface 12A (4A) on which the connection layer 22 is formed and the insertion side inner surface 12B (4B) are in surface contact in a crimped state.

In the structure 2 described above, the inserting side outer surface 12A (4A) and the inserted side inner surface 12B (4B) of the truncated cone-shaped convex through hole 10 have the same taper angle θ, so that the inserting side outer surface 12A (4A) and the inserted side inner 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 simply by fitting the convex through hole 10, and the distance between the stacked circuit boards 4A and 4B can be shortened to obtain a compact structure 2. This makes it 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 reliably electrically connected and connected with sufficient mechanical strength.

Although the embodiments and modes of implementation of the present invention have been described, the disclosed contents may vary in the details of the configuration, and the combination and order of elements in the embodiments and modes of implementation may be changed without departing from the scope and concept of the claimed invention.

2 Structure 4 Circuit board 4A One circuit board 4B The other circuit board 6 Board body 6A First surface 6B Second surface 10 Convex through hole 12 Side portion 12A Outer surface 12B Inner surface 14 Top surface portion 14A Top 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 Connection portion S, SA, SB Internal space

Claims (15)

a substrate body having a region formed of a planar member of a predetermined thickness having a first surface and a second surface which is an opposite surface of the first surface;
a hollow convex through hole formed by the planar member, the first surface being a convex truncated cone-shaped outer side and top surface, the second surface being a concave truncated cone-shaped inner side and top surface, and having an opening penetrating between the top surface and the top surface;
a connection layer formed by connecting a conductive layer formed on the outer side surface and the top surface of the convex through hole and a conductive layer formed on the inner side surface and the ceiling surface of the convex through hole with a conductive layer formed on 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
an insertion-side outer surface which is the outer surface of the convex through hole of one of the circuit boards and an insertion-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, the insertion side outer surface being inserted into an internal space surrounded by the inserted side inner surface, and the insertion side outer surface on which the connection layer is formed and the inserted side inner surface having a fitting structure in which the hollow convex through holes are in surface contact in a crimped state. a substrate body having a region formed of a planar member of a predetermined thickness having a first surface and a second surface which is an opposite surface of the first surface;
a hollow convex through hole formed by the planar member, the first surface being a convex truncated cone-shaped outer side and top surface, the second surface being a concave truncated cone-shaped inner side and top surface, and having an opening penetrating between the top surface and the top surface;
a connection layer formed by connecting a conductive layer formed on the outer side surface and the top surface of the convex through hole and a conductive layer formed on the inner side surface and the ceiling surface of the convex through hole with a conductive layer formed on 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
an insertion-side outer surface which is the outer surface of the convex through hole of one of the circuit boards and an insertion-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 insertion side inner surface, and the insertion side outer surface on which the connection layer is formed and the insertion side inner surface have a fitting structure in which the hollow convex through holes are in surface contact in a crimped state ;
A structure having a conductive pattern , 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 . 3. The structure according to claim 2 , 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. a substrate body having a region formed of a planar member of a predetermined thickness having a first surface and a second surface which is an opposite surface of the first surface;
a convex through hole formed by the planar member, the first surface being a convex truncated cone-shaped outer side and top surface, the second surface being a concave truncated cone-shaped inner side and top surface, and having an opening penetrating between the top surface and the top surface;
a connection layer formed by connecting a conductive layer formed on the outer side surface and the top surface of the convex through hole and a conductive layer formed on the inner side surface and the ceiling surface of the convex through hole with a conductive layer formed on 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
an insertion-side outer surface which is the outer surface of the convex through hole of one of the circuit boards and an insertion-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 insertion side inner surface, and the insertion side outer surface on which the connection layer is formed and the insertion side inner surface have a surface contact in a crimped state.
The connection layer is composed of a plurality of divided connection layers that are divided in a circumferential direction and insulated from each other,
A structure having a conductive pattern, in which when the insertion side outer surface and the inserted side inner surface on which the split connection layer is formed are in surface contact in a crimped state, the split connection layers formed on the insertion side outer surface and the inserted side inner surface are arranged at the same position in the circumferential direction . The structure of claim 4 , wherein the conductive pattern formed on the first surface is connected to one of the split connection layers, and the conductive pattern formed on the second surface is connected to the other of the split connection layers. a substrate body having a region formed of a planar member of a predetermined thickness having a first surface and a second surface which is an opposite surface of the first surface;
a convex through hole formed by the planar member, the first surface being a convex truncated cone-shaped outer side and top surface, the second surface being a concave truncated cone-shaped inner side and top surface, and having an opening penetrating between the top surface and the top surface;
a connection layer formed by connecting a conductive layer formed on the outer side surface and the top surface of the convex through hole and a conductive layer formed on the inner side surface and the ceiling surface of the convex through hole with a conductive layer formed on 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
an insertion-side outer surface which is the outer surface of the convex through hole of one of the circuit boards and an insertion-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 insertion side inner surface, and the insertion side outer surface on which the connection layer is formed and the insertion side inner surface have a surface contact in a crimped state.
two or more connecting portions for connecting an end portion of the board body of the one circuit board to an end portion of the board body of the other circuit board;
A structure in which 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 mated convex through hole . the taper angle is an elevation angle of the truncated cone-shaped convex through hole with respect to a virtual bottom surface,
The structure according to claim 1 , wherein the taper angle is in the range of 40° to 80°. 7. The structure according to claim 1, 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. 7. The structure according to claim 1, 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. an inner diameter of the ceiling surface of the convex through hole of the other circuit board is smaller than an outer diameter of the top surface of the convex through hole of the one circuit board;
When the insertion side outer surface and the insertion side inner surface are in surface contact in a crimped state, a clearance is provided between the top surface and the ceiling surface,
The structure according to claim 1 , wherein the entire area of the inserted-side inner surface on the insertion direction front side of the clearance region is in surface contact with the inserted-side outer surface in a crimped state. the one circuit board and the other circuit board have the convex through holes of the same shape,
The structure according to claim 10 , wherein the inserting side outer surface is inserted into an internal space surrounded by the inserted side inner surface having an inner diameter smaller than an outer diameter of the outer surface due to a thickness of the planar member. The structure according to claim 1 , wherein a plurality of the convex through holes are formed in one of the circuit boards. The structure according to claim 1 , wherein three or more of the circuit boards are connected by the convex through-holes. The structure according to claim 1 , wherein the circuit board is a molded interconnect device (MID) having a three-dimensional shape. The structure according to claim 1 , wherein 70% or more of the area of the insertion side outer surface is in surface contact with the insertion side inner surface in a compressed state.

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