Semi-flexible circuit board

Abstract

The present invention provides a semi-flexible circuit board that can alleviate the stress generated when the flexible part is bent. [Solution] The semi-flexible circuit board 220 comprises a first main part and a second main part 21, 22 which are rigid substrates, and a flexible part 25 which connects the first main part 21 and the second main part 22, is formed to be thinner than the first main part and the second main part 21, 22, and has greater flexibility than the first and second main parts 21, 22. The first main part and the second main part 21, 22 have a plurality of slits 21h, 22h arranged in rows at positions facing the flexible part 25.

Description

Technical Field

[0001] The present disclosure relates to a semi-flexible circuit board.

Background Art

[0002] The semi-flexible printed circuit board described in Patent Document 1 includes a semi-flexible segment that can be bent by having an opening (see FIG. 3 and paragraph 0021 of Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the configuration described in Patent Document 1 above, when the semi-flexible segment is bent, stress easily reaches mounted objects such as electronic components and solder parts on the core substrate, which is not preferable from the viewpoint of the operational stability of the circuit board.

[0005] The present disclosure has been made in view of the above actual situation, and an object thereof is to provide a semi-flexible circuit board capable of relaxing stress generated when the flexible portion is bent.

Means for Solving the Problems

[0006] To achieve the above object, the semi-flexible circuit board according to the present disclosure includes a first main part and a second main part that are rigid boards, and a flexible portion that connects between the first main part and the second main part, is formed thinner than the first main part and the second main part, and has flexibility that is more easily bent than the first main part and the second main part. The first main portion and the second main portion have a plurality of slits arranged in a row at positions facing at least a portion of the flexible portion. [Effects of the Invention]

[0007] According to this disclosure, it is possible to alleviate the stress generated when the flexible part is bent. [Brief explanation of the drawing]

[0008] [Figure 1] This is a plan view of a flat semi-flexible circuit board according to the first embodiment of the present disclosure. [Figure 2] This is a front view of a flat semi-flexible circuit board according to the first embodiment of the present disclosure. [Figure 3] This is a front view of a semi-flexible circuit board in a state in which the flexible portion according to the first embodiment of this disclosure is bent. [Figure 4] This is a plan view of a blank substrate according to the first embodiment of this disclosure. [Figure 5] This is a plan view of a semi-flexible circuit board having a connecting discard substrate portion according to the first embodiment of this disclosure. [Figure 6] This is a magnified view of a portion of Figure 5. [Figure 7] This is a cross-sectional view of the line VII-VII in Figure 6. [Figure 8] This is an enlarged plan view of a portion of a blank substrate according to a modified example of the first embodiment of the present disclosure. [Figure 9] This is an enlarged plan view of a portion of a blank substrate according to a modified example of the first embodiment of the present disclosure. [Figure 10] This is a plan view of a flat semi-flexible circuit board according to a modified example of the first embodiment of the present disclosure. [Figure 11] These are a front view and a side view of a semi-flexible circuit board in a state where the flexible part of the comparative example is bent. [Figure 12] This is a plan view of a flat semi-flexible circuit board according to a second embodiment of the present disclosure. [Figure 13] It is an enlarged view of FIG. 12. [Figure 14] It is a plan view of a semi-flexible circuit board in a flat state according to a modified example of the second embodiment of the present disclosure. [Figure 15] It is a plan view of a semi-flexible circuit board in a flat state according to a modified example of the second embodiment of the present disclosure. [Figure 16] It is a plan view of a semi-flexible circuit board in a flat state according to a modified example of the second embodiment of the present disclosure. [Figure 17] It is a plan view of a semi-flexible circuit board in a flat state according to a modified example of the second embodiment of the present disclosure.

Mode for Carrying Out the Invention

[0009] (First Embodiment) The semi-flexible circuit board and the blank board according to the first embodiment of the present disclosure will be described with reference to the drawings. The semi-flexible circuit board 20 shown in FIGS. 1 to 3 is formed by cutting a part of a rigid circuit board and thinning it, and the thin part is configured to be bendable. The semi-flexible circuit board 20 is, for example, a board mounted on a vehicle, and as an example, it is an ECU (Electronic Control Unit) board for a power steering mounted near a motor shaft.

[0010] The semi-flexible circuit board 20 includes a first main part 21, a second main part 22, a flexible part 25, and a mounting element 40. In the following description, the XY directions are set to be directions orthogonal to each other along the plane direction of the first main part 21, and the Z direction is set to be the thickness direction of the first main part 21. The X direction is the direction in which the first and second main parts 21 and 22 are arranged in a flat state without the flexible part 25 being bent.

[0011] The first and second main parts 21 and 22 are each made of a rigid substrate and are in the shape of a rectangular (e.g., square) plate. The first and second main parts 21 and 22 are circuit boards, for example, 8-layer boards. The first and second main parts 21 and 22 are less flexible than the flexible part 25. Various mounting elements 40 are mounted on both sides 211, 212, 221, and 222 of the first and second main parts 21 and 22.

[0012] As shown in FIG. 3, the flexible part 25 has flexibility to bend in a U shape or a C shape and connects between the first main part 21 and the second main part 22. The flexible part 25 is in the shape of a rectangular plate with a thickness thinner than that of the first and second main parts 21 and 22. The flexible part 25 has a layer structure (e.g., a two-layer structure) for conducting between the first and second main parts 21 and 22.

[0013] As shown in FIGS. 1 and 2, the flexible part 25 is formed between the opposing side surfaces 21a and 22a of the first and second main parts 21 and 22. The flexible part 25 is located at the central part of the opposing side surfaces 21a and 22a in the Y direction and at the end part in the Z direction (the lower end part in FIG. 2) of the opposing side surfaces 21a and 22a.

[0014] As shown in FIG. 2, a recess 28 is formed between the flexible part 25 and the opposing side surfaces 21a and 22a. The flexible part 25 is formed by thinning a raw material formed of the same thickness and material as the first and second main parts 21 and 22 with a tool 80. When the flexible part 25 is in a flat state, the surface (the lower surface in FIG. 2) on the opposite side of the opening side of the recess 28 in the flexible part 25 is flush with the surfaces 212 and 222 of the first and second main parts 21 and 22.

[0015] As shown in FIG. 1, the first and second main parts 21 and 22 include opposing side surfaces 21a and 22a and convex parts 21b and 22b. The opposing side surfaces 21a and 22a are the side surfaces that face each other when the flexible part 25 is in a flat state among the four side surfaces of the first and second main parts 21 and 22. The protrusions 21b and 22b are located on both sides of the flexible portion 25 in the Y direction among the opposing sides 21a and 22a. Each protrusion 21b on the opposing side 21a and each protrusion 22b on the opposing side 22a face each other in the X direction. Of the opposing sides 21a and 22a, the surface roughness of the region Ar1 on the mutually opposing surfaces of the protrusions 21b and 22b is different from the surface roughness of the region Ar2 on the surfaces other than the protrusions 21b and 22b. Specifically, the surface roughness of region Ar1 is formed to be rougher than the surface roughness of region Ar2.

[0016] When the semi-flexible circuit board 20 is mounted on the vehicle, the flexible portion 25 is bent into a roughly C-shape, as shown in Figure 3. In this state, the surface 211 of the first main portion 21 and the surface 221 of the second main portion 22 face each other.

[0017] Next, with reference to Figure 4, the flat blank substrate 10 that serves as the raw material for the semi-flexible circuit board 20 will be described. The semi-flexible circuit board 20 with the connecting sacrificial substrate portion 15 is cut out from the blank substrate 10. The blank substrate 10 is a rectangular plate extending in the XY plane, and in this example, it is a rectangular plate that is long in the X direction.

[0018] The blank substrate 10 comprises a plurality of semi-flexible circuit boards 20, an outer peripheral sacrificial substrate portion 11, and a plurality of connected sacrificial substrate portions 15. The outer perimeter sacrificial substrate section 11 forms a rectangular frame surrounding the outer perimeter of the blank substrate 10. Within the outer perimeter sacrificial substrate section 11, multiple semi-flexible circuit boards 20 are arranged in the X and Y directions. In this example, four semi-flexible circuit boards 20 are arranged in the Y direction, and two semi-flexible circuit boards 20 are arranged in the X direction.

[0019] The outer periphery waste substrate portion 11 and the outer surfaces of the multiple semi-flexible circuit boards 20 are connected by multiple connection portions 19a. Slits 19h are formed between the multiple connection portions 19a. Multiple semi-flexible circuit boards 20 are connected by multiple connection points 19b. Slits 19i are formed between the multiple connection points 19b.

[0020] As shown in Figure 5, the multiple connecting sacrificial substrate portions 15 are arranged on both sides of the flexible portion 25 in the Y direction among the opposing sides 21a, 22a, and are formed to connect the aforementioned protrusions 21b, 22b (see Figure 1) in the X direction. The connecting sacrificial substrate portions 15 are formed of the same material and thickness as the first and second main portions 21, 22, and are formed on the same plane as the first and second main portions 21, 22.

[0021] As shown in Figure 6, the connecting sacrificial substrate section 15 comprises a main body section 15a and two connecting sections 15b. The main body section 15a is rectangular in shape. The connecting sections 15b connect the main body section 15a to the opposing sides 21a and 22a. The length of the connecting section 15b in the Y direction is shorter than the length of the main body section 15a in the Y direction. The connecting section 15b is located approximately in the center in the Y direction of the surface of the main body section 15a facing the opposing sides 21a and 22a. A roughly U-shaped or C-shaped slit 19c is formed between the connecting sacrificial substrate section 15, the flexible section 25, and the opposing sides 21a and 22a.

[0022] The lengths of the first and second main parts 21 and 22 in the Y direction are the same as the sum of the lengths of the flexible part 25 in the Y direction, the lengths of the two connecting sacrificial substrate parts 15 in the Y direction, and the width of the holes of the two slits 19c.

[0023] The hole width (length in the short direction of the slit) of the through-hole elongated slits 19h, 19i, and 19c is set to approximately 2 mm, for example, 1.5 mm to 2.5 mm. A V-groove 15v is formed in the connecting portion 15b, which is longitudinally sectional in the Y direction. The V-groove 15v is formed to separate the connecting sacrificial substrate portion 15 from the first and second main portions 21 and 22 when the flexible portion 25 is bent. As shown in Figure 7, the V-groove 15v is formed on both sides of the connecting waste substrate portion 15. The thickness of the connecting sacrificial substrate section 15 is approximately 1.6 mm, and the depth of one V-groove 15v is approximately 0.5 mm. Note that the V-groove 15v may be any groove, such as a U-shaped groove. Furthermore, a slit may be formed in place of or in addition to this groove.

[0024] Next, we will describe the manufacturing methods for the blank substrate 10 and the semi-flexible circuit board 20. First, in order to manufacture the blank substrate 10, slits 19h, 19i, and 19c are formed on the circuit board material using a tool, a V-groove 15v is formed, and the area corresponding to the flexible part 25 is thinned using a tool 80. This completes the manufacture of the blank substrate 10.

[0025] Next, solder paste is printed onto each semi-flexible circuit board 20 of the blank substrate 10, and then mounting elements 40 are placed on top of it. Reflow is then performed in a reflow oven, where heat is applied to melt the solder. During this reflow process, the rigidity of the blank substrate 10 in a sheet state is increased by the connecting waste substrate section 15, which suppresses the warping of the blank substrate 10 in the reflow oven.

[0026] Then, the connecting portions 19a and 19b between the slits 19h and 19i are cut by a tool such as a router. This cuts out a semi-flexible circuit board 20 having a connecting discard board portion 15 from the blank board 10. Because this cut-out semi-flexible circuit board 20 has a connecting discard board portion 15, unintended bending during handling when it is transported is suppressed.

[0027] Next, when the semi-flexible circuit board 20, which has connecting discard substrate sections 15, is assembled to the object to be assembled, the flexible section 25 bends into a roughly C-shape, and as this bending occurs, each connecting discard substrate section 15 is separated from the semi-flexible circuit board 20 along the V-groove 15v. This bending operation is performed, for example, by hand. At this time, the direction of bending of the flexible portion 25 is the direction in which the bottom surface 28b of the recess 28 (see Figure 3) is recessed. As each connecting discard substrate portion 15 is separated from the semi-flexible circuit board 20, protrusions 21b and 22b (see Figure 1) remain on the opposing side surfaces 21a and 22a as the remaining parts of each connecting discard substrate portion 15.

[0028] The opposing surfaces of the protrusions 21b and 22b are surfaces fractured along the V-groove 15v, while the opposing surfaces 21a and 22a other than the protrusions 21b and 22b are surfaces created by the tool when forming the slit 19c. Therefore, as described above, the surface roughness of regions Ar1 and Ar2 (see Figure 1) is different, and in this example, the surface roughness of the fractured region Ar1 is rougher than the surface roughness of region Ar2 created by the tool.

[0029] In the comparative example without the connecting sacrificial substrate portion 15, as shown in Figure 11, when the flexible portion 525 is bent, the flexible portion 525 may unintentionally twist, bulge, or wrinkle. In this embodiment, however, when the flexible portion 25 is bent, each connecting sacrificial substrate portion 15 supports the flexible portion 25 until each connecting sacrificial substrate portion 15 falls off, thus suppressing the unintentional twisting, bulging, or wrinkling of the flexible portion 25.

[0030] (Effects of the first embodiment) The first embodiment described above provides the following effects. (1) The semi-flexible circuit board 20 comprises first and second main parts 21 and 22 which are rigid substrates, and a flexible part 25 which connects the first and second main parts 21 and 22, is formed thinner than the rigid substrates, and has greater flexibility than the rigid substrates. The first and second main parts 21 and 22 each have opposing sides 21a and 22a that face each other when the flexible part 25 is in a flat state without bending. The opposing sides 21a and 22a are formed so that the surface roughness differs in parts of the opposing sides 21a and 22a. In this configuration, because the surface roughness differs within the opposing sides 21a and 22a, a connecting sacrificial substrate portion 15 is originally formed to connect the first and second main portions 21 and 22. Therefore, the connecting sacrificial substrate portion 15 can prevent the flexible portion 25 from bending unintentionally. For example, it is possible to suppress the unexpected bending of the flexible part 25 during handling.

[0031] (2) The opposing sides 21a and 22a have convex portions 21b and 22b that are partially convex. With this configuration, because of the protrusions 21b and 22b, a connecting sacrificial substrate portion 15 is originally formed to connect the first and second main portions 21 and 22. Therefore, the connecting sacrificial substrate portion 15 can prevent the flexible portion 25 from bending unintentionally.

[0032] (3) The blank substrate 10 having a plurality of semi-flexible circuit boards 20 comprises an outer peripheral sacrificial substrate portion 11 surrounding the outer periphery of the blank substrate 10, and a connecting sacrificial substrate portion 15 that connects the opposing side surface 21a of the first main portion 21 and the opposing side surface 22a of the second main portion 22 and is less prone to bending than the flexible portion 25. With this configuration, the connecting waste substrate portion 15 can prevent the flexible portion 25 from bending unintentionally. For example, it is possible to reduce the warping of the blank substrate 10 inside the reflow oven.

[0033] (Modification of the first embodiment) In the first embodiment described above, the position and number of the flexible portion 25 and the connecting discard substrate portion 15 can be changed as appropriate. For example, as shown in Figure 8, there may be only one flexible section 125 and one connecting sacrificial substrate section 15 connecting the first and second main sections 21 and 22. The flexible section 125 may be formed over an area that extends to the omitted connecting sacrificial substrate section 15. That is, the flexible section 125 is provided biasedly to one side in the Y direction (the lower side in Figure 8) of the opposing sides 21a and 22a. In this modified example, the length of the flexible section 125 in the Y direction can be secured, allowing many wires to be passed between the first and second main sections 21 and 22. Also, because there are fewer connecting sacrificial substrate sections 15, the effort required to detach the connecting sacrificial substrate sections 15 can be reduced. Furthermore, as shown in Figure 9, two flexible sections 225 and one connecting sacrificial substrate section 15 may be provided between the first and second main sections 21 and 22. One connecting sacrificial substrate section 15 may be located in the center of the opposing sides 21a and 22a in the Y direction, and the two flexible sections 225 may be located on both sides of the connecting sacrificial substrate section 15 in the Y direction. Multiple flexible sections 225 allow many wires to pass between the first and second main sections 21 and 22, and dividing the flexible section 225 into two increases the degree of freedom in wiring.

[0034] In the first embodiment described above, V-grooves 15v were formed so that each connecting sacrificial substrate portion 15 would be separated from the first and second main portions 21 and 22 when the flexible portion 25 was bent. However, the V-grooves 15v may be omitted. In this case, each connecting sacrificial substrate portion 15 would be separated from the first and second main portions 21 and 22 by a tool such as a drill.

[0035] In the first embodiment described above, the protrusions 21b and 22b may be omitted, and the opposing surfaces 21a and 22a may be planar. In this case, as shown in Figure 10, the surface roughness of a portion of the opposing surfaces 21a and 22a, specifically region Ar1, may be formed to be rougher than the surface roughness of the other region Ar2. Region Ar1 is provided at a position corresponding to the protrusions 21b and 22b in the first embodiment described above. In the first embodiment described above, the connecting waste substrate portion 15 may be formed thinner than the first and second main portions 21 and 22. In the first embodiment described above, the connecting sacrificial substrate portion 15 may be connected to sides other than the opposing sides 21a and 22a of the first and second main portions 21 and 22.

[0036] (Second Embodiment) A semi-flexible circuit board according to the second embodiment of this disclosure will be described with reference to the drawings. This embodiment differs from the first embodiment in that dashed slits are formed in the first and second main parts of the semi-flexible circuit board. The differences from the first embodiment will be described below.

[0037] As shown in Figure 12, in the semi-flexible circuit board 220 of this embodiment, a plurality of slits 21h are formed in the first main portion 21, and a plurality of slits 22h are formed in the second main portion 22. Each slit 21h, 22h is formed as an elongated hole that is long in the Y direction. As shown in Figure 13, multiple slits 21h and multiple slits 22h are arranged in a row with a spacing B in the Y direction. The arrangement direction of the slits 21h and 22h is parallel to the opposing sides 21a and 22a. Multiple wirings La (see Figure 12) leading to the flexible portion 25 pass through the spacing B. Multiple slits 21h are provided at a distance A from the opposing side surface 21a, and multiple slits 22h are provided at a distance A from the opposing side surface 22a. The multiple slits 21h and 22h are formed in a range facing the flexible portion 25 in the X direction. No mounted components such as mounted elements 40 or solder parts are present between the slits 21h, 22h and the opposing side surfaces 21a, 22a. The Y-direction arrangement range L2 of the slits 21h and 22h is formed within the range that includes the flexible portion 25 when viewed from the X-direction. The Y-direction center position of the arrangement range L2 coincides with the Y-direction center position of the flexible portion 25. In other words, the multiple slits 21h and 22h are arranged so as not to be biased in the Y-direction relative to the flexible portion 25.

[0038] The hole width W of the slits 21h and 22h is set to, for example, 0.7 mm to 1.3 mm, preferably about 1 mm. The hole length L1 of the slits 21h and 22h is greater than the hole width W, for example, 1 mm or more, preferably 1.5 mm to 2.5 mm, more preferably about 2 mm. The spacing B between the slits 21h and 22h (the spacing between the slit ends facing each other in the Y direction) is set to be greater than or equal to the thickness of the first and second main parts 21 and 22, i.e., 1.6 mm or more. Furthermore, the spacing B is set to be smaller than the hole length L1. The spacing B is set to, for example, 1.6 mm to 2.0 mm. The larger the spacing B, the more the number and spacing of wiring La passing through the flexible part 25 can be increased, and the smaller the spacing B, the more stress can be concentrated in the region from the slits 21h and 22h to the flexible part 25 when the flexible part 25 is bent. The distance A is set to, for example, 0.7 mm to 1.3 mm, preferably about 1 mm.

[0039] In the comparative example without slits 21h and 22h, as in Figure 3 above, when the flexible part 25 is bent, the stress generated in the first and second main parts 21 and 22 reaches the mounted element 40 and the solder joint, causing the mounted element 40 to break or the solder joint to crack. On the other hand, if the mounted element 40 and the solder joint are to be formed in a position where this stress does not reach, the first and second main parts 21 and 22 become larger. In this embodiment, by forming multiple slits 21h, 22h in the first and second main parts 21, 22, when the flexible part 25 is bent, the first and second main parts 21, 22 can concentrate stress between the slits 21h, 22h and the opposing sides 21a, 22a, thereby mitigating the stress that reaches the mounted element 40 and the solder joint. This makes it possible to suppress the destruction of the mounted element 40 and cracks in the solder joint.

[0040] (Effects of the second embodiment) The second embodiment described above provides the following effects. (1) The semi-flexible circuit board 220 comprises a first main part and a second main part 21, 22 which are rigid substrates, and a flexible part 25 which connects the first main part 21 and the second main part 22, is formed to be thinner than the first and second main parts 21, 22, and has greater flexibility than the first and second main parts 21, 22. The first and second main parts 21, 22 have a plurality of slits 21h, 22h arranged in a row at positions facing the flexible part 25. Wiring La passes between the plurality of slits 21h, 22h and the opposing sides 21a, 22a, without any mounted elements 40 or solder parts. With this configuration, as described above, the multiple slits 21h and 22h can alleviate the stress reaching the mounted element 40 and the solder joint. Furthermore, wiring La extending from the first main section and the second main section 21, 22 to the flexible section 25 can be passed between the multiple slits 21h, 22h.

[0041] (2) The first and second main parts 21 and 22 each face each other when the flexible part 25 is in a flat state without bending, and have opposing sides 21a and 22a to which the flexible part 25 is connected. The multiple slits 21h and 22h are arranged in a single row in the direction along the opposing sides 21a and 22a. With this configuration, as described above, the multiple slits 21h and 22h can alleviate the stress reaching the mounted element 40 and the solder joint.

[0042] (Modified version of the second embodiment) In the second embodiment described above, the positions of the multiple slits 21h and 22h in the Y direction can be changed as appropriate. For example, as shown in Figure 14, the Y-direction center position C1 of the array range L2 may be located on one side in the Y direction (the lower side in Figure 14) than the Y-direction center position C2 of the flexible portion 25. That is, the multiple slits 21h and 22h may be arranged off-center in the Y direction relative to the flexible portion 25. This increases the degree of freedom of the wiring extending from the first main portion 21 and the second main portion 22 to the flexible portion 25. In this modified example as well, some of the multiple slits 21h and 22h face some of the flexible portion 25 in the X direction. In this modification, the distance D between the center positions C1 and C2 is preferably 2 / 3 or less of the length of the flexible portion 25 in the Y direction. However, it is not limited to this, and the distance D may exceed 2 / 3 of the length of the flexible portion 25 in the Y direction.

[0043] In the second embodiment described above, the multiple slits 21h, 22h were arranged in one row in each main section 21, 22, but they may be arranged in multiple rows in each main section 21, 22. For example, as shown in Figure 15, multiple slits 121h, 122h, 221h, 222h may be arranged in two rows in each main section 21, 22. The positions of the slits 121h, 122h in the first row and the slits 221h, 222h in the second row may be at the same position in the Y direction. The spacing E between the first row and the second row may be set to be greater than or equal to the thickness of each main section 21, 22. Furthermore, as shown in Figure 16, the positions of the slits 121h, 122h in the first row and the slits 221h, 222h in the second row may be offset in the Y direction. That is, the slits 121h, 122h, 221h, 222h may be arranged in a staggered pattern. This arrangement of slits 121h, 122h, 221h, 222h makes it more difficult for stress to be transmitted to the mounted element 40 when the flexible part 25 is bent.

[0044] In the second embodiment described above, the multiple slits 21h and 22h were arranged in a straight line in the Y direction, but they may also be arranged in a curved or wave-like shape (rectangular wave or sinusoidal wave). For example, as shown in Figure 17, the multiple slits 21h and 22h may be arranged in an arc shape. The multiple slits 21h are arranged so as to surround the portion of the opposing side surface 21a that is connected to the flexible portion 25, and the multiple slits 22h are arranged so as to surround the portion of the opposing side surface 22a that is connected to the flexible portion 25. This makes it difficult for the stress when the flexible portion 25 is bent to be transmitted beyond the multiple slits 21h and 22h to the mounting element 40 side. In this case, the multiple slits 21h and 22h may be arranged on the outer circumference of a common virtual circle Cr. Note that the multiple slits 21h and 22h do not have to be arranged on the outer circumference of a common virtual circle Cr.

[0045] In the second embodiment described above, at least one of the multiple slits 21h, 22h may be a circular hole. For example, the second slit 21h from the outside (upper side) in the Y direction of the multiple slits 21h may be formed as a circular hole.

[0046] The configurations shown in Figures 12 to 17 can be combined as appropriate. For example, multiple slits 21h and 22h may be arranged in a staggered pattern along multiple arc lines. Alternatively, in the configurations shown in Figures 15 to 17, the center position of the arrangement range of multiple slits may be shifted from the center position of the flexible section 25, as shown in Figure 14. Furthermore, the arrangement of the slits may differ between the first main section 21 and the second main section 22.

[0047] This disclosure is not limited to the embodiments and drawings described above. Modifications (including the deletion of components) can be made as appropriate, provided they do not alter the essence of this disclosure. An example of such a modification is described below.

[0048] (Complete variation) In the above embodiments and their modified examples, the number of main parts 21 and 22 was two, but there may be three or more, and in this case, the number of flexible parts 25 may also be two or more. In the above embodiments and their modified forms, the semi-flexible circuit boards 20 and 220 were mounted on a vehicle, but they may be mounted on something other than a vehicle. In the above embodiments and their modifications, the slit may be a round hole instead of an elongated hole. Furthermore, the slit may be a through hole or a closed hole. Also, the slit may be a notch. The first embodiment and its modified form described above and the second embodiment and its modified form can be combined. For example, the slits 21h, 22h, 121h, 122h, 221h, and 222h in Figures 12 to 17 of the second embodiment and its modified form can be applied to the configuration shown in Figures 1 to 10 of the first embodiment and its modified form. [Explanation of Symbols]

[0049] 10…Blank circuit board 11... Outer perimeter sacrificial substrate section 15...Connecting detachable substrate section, 15a...Main body section, 15b...Connecting section, 15v...V groove 19a, 19b... Connection part 19c, 19h, 19i, 21h, 22h, 121h, 122h, 221h, 222h… Slit 20,220... Semi-flexible circuit board 21...First main part, 22...Second main part, 21a, 22a...Opposing side, 21b, 22b...Convex part, 211,212,221,222...Surface 25, 125, 225, 525... Flexible section, 28... Recessed section, 28b... Bottom surface 40…Implemented elements 80...Tools A, D…Distance, B…Spacing, C1, C2…Center position, L1…Hole length, L2…Alignment range, W…Hole width, La…Wiring, Ar1, Ar2…Region, Cr…Virtual circle

Claims

1. The first main part and the second main part are rigid substrates, A flexible portion is provided, which connects the first main portion and the second main portion, is formed to be thinner than the first main portion and the second main portion, and has greater flexibility than the first main portion and the second main portion. The first main part and the second main part have a plurality of slits arranged in a row at positions facing at least a part of the flexible part. Semi-flexible circuit board.

2. The first main part and the second main part each face each other in a flat state in which the flexible part does not bend, and have opposing sides to which the flexible part is connected. The plurality of slits are arranged in a row in the direction along the opposing side surface. The semi-flexible circuit board according to claim 1.

3. The plurality of slits are arranged in multiple rows in the first main part and the second main part, A semi-flexible circuit board according to claim 1 or 2.

4. The first main part and the second main part each have opposing sides that face each other when the flexible part is in a flat state without bending. The plurality of slits are arranged in an arc shape so as to surround the portion of the opposing side surface to which the flexible portion is connected. The semi-flexible circuit board according to claim 1.

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