Wiring board and manufacturing method of the same

Abstract

To provide a wiring board and a manufacturing method of the same, which are capable of preventing disconnection of a stress concentration portion extending from a main body part to a tail portion by a simple method.SOLUTION: A wiring board includes: a base material 2 having a sheet-like main body part A1 and a tail part A2 extending from one end of the main body part A1 in a plan view of the main body part A1 in a shape having a width narrower than that of the main body part 1A; a conductive layer 3 formed on a first surface of the base material 2; a protective layer 4 formed on the conductive layer 3; and a rigid layer 5 covering the conductive layer 3 located on the tail part A2 and having a terminal on the main body part A1 side forming a boundary line 5A between the tail part A2 and the main body part A1 on the tail part A2. The base material 2 includes a stretching suppressing part 20 overlapping with a boundary region E including the boundary line 5A in the plan view, and the stretching suppressing part 20 is continuous with the tail part main body via a folded part on the outer side in a width direction of the tail part A1.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a wiring board used as a flexible touch sensor module and a manufacturing method thereof. [Background technology]

[0002] BACKGROUND ART In recent years, wiring boards on which electronic components such as sensors are mounted have been used as measuring instruments for wearable devices, medical devices, and the like. The wiring board has a base layer made of a flexible material and a conductive layer. The conductive layer is an expandable circuit having an electrode portion that serves as a sensor portion, a wiring portion having one end connected to the electrode portion, and a terminal portion connected to the other end of the wiring portion. Such wiring boards are required to be able to deform to conform to the flexible adherend so as not to impair the feel and comfort of the adherend. However, due to this flexibility, there is a problem in that the circuit extending from the main body of the substrate to the tail portion where the connection terminals for external devices are located is prone to breakage.

[0003] As a countermeasure, the wiring board shown in Patent Document 1 has a structure in which an adhesive layer is provided on one side or the other side of the stretchable base material, thereby preventing breakage of the wiring.

[0004] In addition, in the wiring board shown in Patent Document 2, a bellows-shaped portion including multiple peaks and valleys is formed in the wiring on the base material, and a reinforcing member having a higher elastic modulus than the surrounding area is provided within the base material. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-96825 [Patent Document 2] Japanese Patent Application Publication No. 2020-170758 Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Document 1 as described above shows a configuration in which a pressure-sensitive adhesive layer is separately provided, and Patent Document 2 shows a configuration in which bellows wiring and a reinforcing member are provided. Another possible structure is to prevent breakage of the wiring by locally increasing the thickness of the base material itself without providing a reinforcing member. However, the configurations described in Patent Documents 1 and 2 have the problem of complicating the manufacturing process, and there has been a desire to provide a technology that can prevent breakage at the stress concentration points extending from the main body portion to the tail portion using a simpler method.

[0007] The present invention has been made in view of the above circumstances, and provides a wiring board and a manufacturing method thereof that can prevent breakage of the stress concentration points extending from the main body portion to the tail portion using a simple method. [Means for solving the problem]

[0008] The present invention has the following aspects. [1] A stretchable substrate having a sheet-like main body portion and a tail portion extending from one end of the main body portion with a width narrower than that of the main body portion in a plan view of the main body portion; a conductive layer formed on a first surface of the substrate; a protective layer formed on the conductive layer; a rigid layer covering the conductive layer located on the tail portion, the rigid layer having an end on the body portion side that forms a boundary between the tail portion and the body portion on the tail portion; a region of a specified length including the boundary line in the tail portion is defined as a boundary region; the base material includes an extension suppression portion that overlaps with the boundary region in the plan view, The extension suppression portion is connected to a tail portion main body via a folded portion on an outer side of the tail portion in a width direction of the wiring board. [2] The extension suppression portion forms an extension region that extends outward in the width direction of the tail portion body when the folded-back portion is unfolded, The wiring board according to [1], wherein the extension suppression portion is formed by folding the extension region so that the extension region overlaps the laminate of the conductive layer, the protective layer, and the rigid layer. [3] The wiring board according to [2], wherein the extension suppressing portion is bonded to the laminate via an adhesive layer. [4] The wiring board according to [2], wherein the extension suppression portion is provided so as to cover the boundary line. [5] The wiring board described in [2], wherein the extension suppression portion is formed so that the end portion in the width direction protrudes toward the main body portion side more than the center portion in the width direction in the area on the main body portion side where the rigid layer is not present. [6] The wiring board according to [2], wherein the folded portion protrudes outward in the width direction beyond the tail portion main body, forming a gap between the folded portion and the edge of the laminate. [7] The extension suppression portion forms an extension region that extends outward in the width direction of the tail portion body when the folded-back portion is unfolded, The wiring board according to [1], wherein the extension suppression portion is formed by folding the extension region so as to overlap a second surface of the base material opposite to the first surface. [8] The wiring board according to [7], wherein the extension suppression portion is formed by bonding the extension region of the base material to the second surface of the base material without an adhesive layer therebetween. [9] The wiring board according to [1], wherein the base material is made of a silicone elastomer.

[10] A process of forming a conductive layer by screen printing on a first surface of a base material before cutting out a substrate having a sheet-like main body portion and a tail portion extending from one end of the main body portion with a width narrower than that of the main body portion in a plan view; forming a protective layer on the conductive layer by screen printing; a step of cutting out an extension region that extends outward in the width direction of the tail portion main body on the width direction outer side of a boundary region between the main body portion and the tail portion defined on the tail portion; and a step of folding and joining the cut-out extension region toward the tail portion main body to form an extension suppression portion that overlaps with the boundary region. [Effects of the Invention]

[0009] According to the present invention, the extension suppression portion is formed by folding the extension region of the base material that extends outward in the width direction at the boundary region between the main body portion and the tail portion. By reinforcing the boundary region, which has a difference in rigidity, with the extension suppression portion, the risk of wire breakage can be reduced. Furthermore, in the wiring board of the present invention, the extension region of the base material is folded to form the extension suppression portion, so that the widthwise end of the boundary region has a U-shaped cross section rather than a rectangular cross section, which increases resistance to tearing from the widthwise end compared to a method of increasing rigidity by overlaying a separate member on the boundary region, thereby reducing the risk of disconnection of the conductive layer. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is a top view showing the wiring substrate according to the first embodiment. [Figure 2] 2 is a cross-sectional view taken along line II-II of the wiring board shown in FIG. [Figure 3] 2 is a top view in which an extension region of a base material in the wiring board shown in FIG. 1 is developed. [Figure 4] 4 is a cross-sectional view taken along line IV of the wiring board shown in FIG. [Figure 5] FIG. 3 is a cross-sectional view corresponding to FIG. 2 of a modified example of the wiring board. [Figure 6] FIG. 10 is an explanatory diagram of the method for manufacturing a wiring board according to the second embodiment, and is a top view of the base material of the substrate. [Figure 7] FIG. 2 is a top view of a base material on which wiring has been printed, which is step 1 of the manufacturing method. [Figure 8] FIG. 2 is a top view of a base material on which a second conductive layer is printed, which is step 2 of the manufacturing method. [Figure 9] FIG. 9 is an enlarged view of part IX in FIG. 8. [Figure 10] FIG. 10 is a top view of a base material on which a protective layer is printed, which is step 3 of the manufacturing method. [Figure 11] FIG. 10 is a top view of the base material after the outer shape cut has been made, which is step 4 of the manufacturing method. [Figure 12]FIG. 10 is a top view of the base material after folding of the extension region, which is step 5 of the manufacturing method. [Figure 13] FIG. 10 is a top view of a base material on which a rigid layer is printed, which is step 6 of the manufacturing method. [Figure 14] FIG. 10 is a top view of a base material on which a reinforcing layer has been printed, which is step 7 of the manufacturing method. [Figure 15] FIG. 10 is a top view of the wiring substrate after the outline cutting has been performed in step 8 of the manufacturing method. [Figure 16] FIG. 10 is a top view of the wiring board to which the housing has been attached, which is step 9 of the manufacturing method. [Figure 17] 10A and 10B are top views showing modified examples of extension suppression portions of the substrate. [Figure 18] FIG. 18 is an enlarged view of the main part in FIG. 17. DETAILED DESCRIPTION OF THE INVENTION

[0011] First Embodiment A first embodiment of a wiring board according to the present invention will be described below with reference to FIGS. In the drawing, arrow Dt indicates the thickness direction of the wiring board 1, arrow D1 indicates the length direction perpendicular to the thickness direction Dt, and arrow D2 indicates the width direction perpendicular to the thickness direction Dt and the length direction D1. 1 and 2, FIG. 1 shows the wiring board 1 before the housing 9 is attached, and FIG. 2 shows the wiring board 1 after the housing 9 is attached.

[0012] First, the wiring substrate 1 shown in Figures 1 and 2 is a flexible touch sensor module, and has a structure in which a conductive layer 3, a protective layer 4, and a rigid layer 5 are sequentially stacked in the thickness direction Dt on a base substrate 2. The substrate 2 is made of a silicone elastomer sheet and has elasticity. The method for molding the silicone elastomer sheet is not particularly limited, but extrusion molding, calendar molding, etc. can be used.

[0013] On a main surface 2a of the substrate 2, a conductive layer 3 made of a conductive material is provided. The conductive layer 3 includes an electrode portion 10 that detects electrical changes on the surface of the protective layer 4, a terminal connection portion 11 that can be connected to an external substrate (not shown), and a wiring portion 12 that connects the electrode portion 10 and the terminal connection portion 11.

[0014] The wiring portion 12 and the terminal connection portion 11 are formed, for example, by screen printing a predetermined pattern using paste ink containing a conductive material. The conductive material contained in the paste ink may be metal particles (silver particles, copper particles, gold particles, etc.), conductive nanowires (silver nanowires, gold nanowires, carbon nanotubes, etc.), conductive metal oxide particles (ITO particles, etc.), carbon (carbon black, graphite, etc.), etc. Furthermore, since flexibility is required for the conductive layer 3, a conductive ink containing resin is preferable, and a silver paste with a low resistance value is particularly preferable. Low-cost screen printing is preferable as a method for forming a circuit using conductive ink. The electrode portion 10 is formed by screen printing a predetermined pattern using, for example, a paste containing a conductive substance or a conductive polymer material such as poly-3,4-ethylenedioxythiophene / polystyrene sulfonate (PEDOT / PSS).

[0015] In the substrate 2 and the conductive layer 3, the points indicated by the symbol M in the figure are stress concentration points. The stress concentration point M occurs in a boundary region E between the main body portion A1 and the tail portion A2 of the substrate 2. When the end of the rigid layer 5 on the main body portion A1 side is defined as a boundary line 5A, the boundary region E is an area of ​​a specified length extending on both sides of the boundary line 5A in the longitudinal direction D1.

[0016] In the embodiment, the wide region of the substrate 2 having the electrode portion 10 and the wiring portion 12 connected to the electrode portion 10, separated by the boundary line 5A within the stress concentration area M, is defined as the main body portion A1, and the narrow region of the substrate 2 having the terminal connection portion 11 and the wiring portion 12 connected to the terminal connection portion 11 is defined as the tail portion A2.

[0017] The protective layer 4 is formed in the same shape as the base material 2 and covers the entire conductive layer 3 on the base material 2. The protective layer 4 is formed of an insulating resin film, and the protective layer 4 can prevent deterioration (oxidation, corrosion) of the conductive layer 3 and the electrode parts 10. As the insulating resin, a thermosetting resin, a visible light curable resin, an electron beam curable resin, or an ultraviolet curable resin can be used, with ultraviolet curable resin being preferred in terms of its small thermal shrinkage during curing. The protective layer 4 is preferably thin as long as it can ensure insulation. The protective layer 4 is formed by screen printing, and the thickness is preferably 5 μm or more to prevent the formation of pinholes. In the tail portion A2, the rigid layer 5 is formed of a cover film that covers the terminal connection portion 11 of the conductive layer 3 and the wiring portion 12 connected to the terminal connection portion 11. The rigid layer 5 increases the strength of the tail portion A2 including the terminal connection portion 11 of the conductive layer 3.

[0018] A reinforcing layer 6 is provided on the back surface (second surface) 2b of the base material 2 located in the tail portion A2. The reinforcing layer 6 is formed of a cover film made of an adhesive resin via an adhesive layer (not shown).

[0019] Examples of resins that make up the cover film include polyethylene terephthalate (PET), polycarbonate, acrylic resin, polyethylene naphthalate, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinyl alcohol, polybutylene terephthalate, polyvinylidene fluoride, polyarylate, etc. Instead of a resin film, the cover film may be a film made of glass, transparent metal oxide, or the like.

[0020] A second conductive layer 7 made of carbon paste is provided on the main surface 2a side of the end portion of the tail portion A2 of the substrate 2. The second conductive layer 7 is formed so as to cover the terminal connection portion 11 of the conductive layer 3.

[0021] Next, the extension suppression section 20, which is a characteristic feature of this embodiment, will be described with reference to FIGS. The extension suppression portion 20 is formed by folding a pair of extension regions A3 (see FIG. 3) formed on both sides of the boundary region E in the tail portion A2 in the width direction D2 so that they overlap on the laminate 50 of the conductive layer 3, the protective layer 4, and the rigid layer 5. The pair of extension regions A3 are formed by opening the extension suppression portion 20 on both sides in the width direction D2 and developing it into a flat shape. Hereinafter, the linear portion of the tail portion A2 excluding the extension regions A3 will be referred to as the tail portion main body A21.

[0022] The extension suppression portion 20 overlaps with the boundary region E in the top view (plan view) shown in Fig. 1. The extension region A3 and the laminate 50 consisting of the conductive layer 3, the protective layer 4, and the rigid layer 5 are bonded to each other by an adhesive layer 51 formed on the inner surface of the base material 2, as shown in Fig. 4. The extension suppression portion 20 is provided so as to cover the entire boundary line 5A in the plan view (so as to overlap the entire boundary line 5A). The extension suppression portion 20 is connected to the tail portion main body A21 on the outer side of the tail portion A2 in the width direction D2 via a pair of folded portions 20A.

[0023] The folded portion 20A is formed on the base end side of the extension region A3. As shown in Fig. 4, the inside of the folded portion 20A is not completely adhered to the edge of the laminate 50 of the conductive layer 3, the protective layer 4, and the rigid layer 5, but has a U-shaped structure in the cross section of Fig. 4, and a gap 20B is formed between the folded portion 20A and the edge of the laminate 50.

[0024] As a result, the stretch suppressing portion 20 protrudes outward in the width direction D2 beyond the overall width W of the tail portion main body A21, as shown in Fig. 4. The folded-back portion 20A forms a protruding portion 21 that is located outward beyond the overall width W of the tail portion main body A21. By releasing stress through the protruding portion 21, the stretch suppressing portion 20 is more likely to suppress tearing from the end portion in the width direction D2.

[0025] The base material 2 has a pair of extending regions A3 extending on both sides of the boundary region E in the width direction D2. The extending regions A3 partially protrude outward in the width direction D2 of the base material 2. The extending regions A3 have a rectangular shape in the unfolded state shown in FIG. 3, ensuring a reinforced area by the stretch suppressing portion 20. The stretch suppressing portion 20 is formed by folding the two extending regions A3.

[0026] 2, the extension suppressing portion 20 is arranged such that the two extending regions A3 are folded and cover the boundary line 5A of the rigid layer 5. In this way, the extension suppressing portion 20 firmly fixes the boundary region E between the main body portion 2A and the tail portion 2B, which have a rigidity difference. The laminate 50 on the base material 2 provided with the extension suppression section 20 is attached to the housing 9, which serves as the adherend, via an adhesive layer 8 (see FIG. 2). Note that the adhesive layer 8 used here is not limited to an adhesive agent, and may be a double-sided tape.

[0027] As described above in detail, according to the wiring board 1 of the first embodiment, an extension suppression portion 20 that reinforces the boundary region E between the main body portion A1 and the tail portion A2 of the base material 2 is formed by folding the extension region A3 that extends outward in the width direction D2 of the base material 2. In the wiring board 1 of the first embodiment, the boundary region E between the main body portion A1 and the tail portion A2, which have different rigidities in the base material 2, is fixed by the extension suppression portion 20, thereby reducing the risk of breakage of the conductive layer 3. Furthermore, the extension suppression section 20 can have a U-shaped cross section (see FIG. 4) at the folded portion of the extension region A3 in the base material 2 instead of a rectangular cross section. This increases resistance to tearing from the end in the width direction D2 compared to a method in which separate members are stacked to improve rigidity, thereby reducing the risk of disconnection of the conductive layer 3.

[0028] Here, in the extension suppression section 20 of the above embodiment, the extension region A3 of the base material 2 is folded so as to overlap the laminate 50 of the conductive layer 3, the protective layer 4, and the rigid layer 5, as shown in FIG. However, the present invention is not limited to the above configuration, and may be configured, for example, as a modified example shown in Fig. 5. That is, the extension suppression portion 20' shown in Fig. 5 is formed by folding a pair of extension regions A3 of the base material 2 so as to overlap with the opposite surface 2b of the base material 2 located on the back surface of the conductive layer 3.

[0029] The extension suppression section 20 or 20′ described above may be formed by fixing the pair of extension regions A3 of the substrate 2 to the main surface 2a or the opposite surface 2b of the substrate 2 via an adhesive layer. Alternatively, the extension regions A3 may be fixed by solid-state bonding using a surface modification treatment without using a material different from the substrate, such as an adhesive. Examples of surface modification treatment methods include ultraviolet irradiation, which causes minimal thermal damage; corona discharge, which allows for rapid processing; plasma discharge, which allows for rapid processing and contributes to strengthening adhesive strength; and flame treatment. When ultraviolet irradiation is employed, it is preferable to irradiate with light having a wavelength equal to or shorter than near ultraviolet (wavelength 380 to 200 nm), preferably far ultraviolet or vacuum ultraviolet (wavelength 200 to 10 nm). In this case, ultraviolet irradiation can be performed using, for example, xenon as the discharge gas and an excimer lamp emitting vacuum ultraviolet (VUV) rays with wavelengths including 172 nm. When plasma discharge is employed, either vacuum plasma discharge or atmospheric pressure plasma discharge may be used.

[0030] Second Embodiment Hereinafter, a method for manufacturing wiring board 1 according to the second embodiment of the present invention will be described with reference to FIGS. In the following description, parts having the same configuration as the first embodiment are denoted by the same reference numerals, and duplicated descriptions will be omitted.

[0031] (Process 1) 6 and 7, a circuit wiring film that will become the conductive layer 3 is formed by screen printing using a metal paste ink on the main surface 2a of a silicone elastomer that will become the base material 2M before cutting out the substrate 2. The conductive layer 3 has electrode portions 10, terminal connection portions 11, and wiring portions 12. At this time, a surface modification treatment may be performed as a pretreatment.

[0032] (Process 2) Next, as shown in FIGS. 8 and 9, in order to use the terminal connection portion 11 of the conductive layer 3 as the second conductive layer 7 that will become a connector, a carbon layer is formed on the terminal connection portion 11 by screen printing.

[0033] (Step 3) Next, as shown in FIG. 10, the protective layer 4 is formed on the conductive layer 3 by screen printing.

[0034] (Step 4) 11, contour cutting is performed to form extension regions A3 that protrude laterally (outward in the width direction D2) in the boundary region E between the main body portion A1 and the tail portion A2 of the base material 2. A pair of extension regions A3 are provided so as to protrude from both sides of the tail portion main body A21 in the width direction D2 and extend outward.

[0035] (Step 5) 12, the extension region A3 of the contour-cut base material 2 is folded and adhered to the upper surface of the laminate (the laminate of the conductive layer 3 and the protective layer 4) located on the boundary region E between the main body portion A1 and the tail portion A2 of the base material 2. This forms the extension suppression portion 20. 12 and the following steps shown in FIGS. 13 to 15, the location indicated by the symbol N is an opening in the base material 2 created by folding the extension region A3.

[0036] (Step 6) Next, as shown in FIG. 13, the rigid layer 5 is attached onto the protective layer 4 of the tail portion A2 of the substrate 2 including the extension-restricted portion 20. Incidentally, step 6 of bonding the rigid layer 5 may be performed before steps 4 and 5, rather than after these steps 4 and 5. That is, after forming a laminate consisting of a conductive layer 3, a protective layer 4, and a rigid layer 5 on the base material 2, steps 4 and 5 may be performed so that the extension area A3 in the base material 2 is folded and covers the upper surface of the boundary line 5A of the rigid layer 5 (see Figure 2).

[0037] (Step 7) Next, as shown in FIG. 14, the reinforcing layer 6 is bonded to the opposite surface 2b of the base material 2 via an adhesive layer (not shown).

[0038] (Step 8) Next, as shown in FIG. 15, the laminate produced in steps 1 to 7 is cut to the outline according to the shapes of the main body portion A1 and the tail portion A2 of the base material 2.

[0039] (Step 9) Next, as shown in FIG. 16, a housing 9 is attached via an adhesive layer 8 to the upper surface of the laminate whose outline has been cut in step 8, thereby completing the production of the wiring board 1.

[0040] As described above in detail, according to the wiring board 1 manufactured in the second embodiment, an extension suppression portion 20 is formed in the boundary region E between the main body portion A1 and the tail portion A2 of the base material 2 by folding the extension region A3 of the base material 2 that extends outward. In the wiring board 1 of this second embodiment, the boundary region E between the main body portion A1 and the tail portion A2 of the substrate 2 having such a difference in rigidity is fixed by the extension suppression portion 20, thereby reducing the risk of breakage. Furthermore, the extension suppression section 20 can have a U-shaped structure (see Figure 3) at the folding point of the extension region A3 in the base material 2 instead of a rectangular shape, which makes it more resistant to tearing from the side compared to a method in which separate components are stacked, thereby reducing the risk of breakage of the conductive layer 3.

[0041] In the above embodiment, the peripheral shape of the extension region A3 of the base material 2 is formed into a rectangular shape in order to ensure a reinforcement area by the extension suppression portion 20 (see FIG. 3). However, the peripheral shape of the extension region A3 is not limited to this, and possible shapes include those shown in Figures 17 and 18. The extension region A3' shown in Figures 17 and 18 is formed so that the widthwise end 20d of the stretch-suppressing portion 20 on the side without the rigid layer 5 protrudes more toward the main body portion A1 than the widthwise central portion 20c of the stretch-suppressing portion 20. This makes it possible to suppress tearing from the widthwise end of the stretch-suppressing portion 20. Furthermore, because the total boundary length of the stretch-suppressing portion 20 on the side without the rigid layer 5 is longer than the width of the tail portion A2, changes in rigidity can be further suppressed.

[0042] Although the present invention has been described above with reference to the embodiments, various modifications that can be understood by those skilled in the art can be made to the configurations and details of the embodiments. Each embodiment can also be combined with other embodiments as appropriate. [Explanation of symbols]

[0043] 1. Wiring board 2 boards 2a Main surface 2b Opposite side 3 Conductive layer 4 protective layer 5 Rigid layer 5A border 6 Reinforcement layer 7 Second conductive layer 8 Adhesive layer 9. Cabinet 10 Electrode section 11 Terminal connection 12 Wiring section 20,20' Stretching suppression part 20A Folded part 20B void 21 Protruding part 50 laminate 51 Adhesive layer A1 Main body A2 Tail section A3 extension area E boundary area M Stress concentration point W width

Claims

1. a stretchable substrate having a sheet-like main body portion and a tail portion extending from one end of the main body portion with a width narrower than that of the main body portion in a plan view; a conductive layer formed on a first surface of the substrate; a protective layer formed on the conductive layer; a rigid layer covering the conductive layer located on the tail portion, the rigid layer having an end on the body portion side that forms a boundary between the tail portion and the body portion on the tail portion; a region of a specified length including the boundary line in the tail portion is defined as a boundary region; the base material includes an extension suppression portion that overlaps with the boundary region in the plan view, The extension suppression portion is connected to a tail portion main body via a folded portion on an outer side of the tail portion in a width direction of the wiring board.

2. The extension suppression portion forms an extension region that extends outward in the width direction of the tail portion main body when the folded-back portion is unfolded, The wiring board according to claim 1 , wherein the extension suppression portion is formed by folding the extension region so that the extension region overlaps the laminate of the conductive layer, the protective layer, and the rigid layer.

3. The wiring board according to claim 2 , wherein the extension suppressing portion is bonded to the laminate via an adhesive layer.

4. The wiring board according to claim 2 , wherein the extension suppressing portion is provided so as to cover the boundary line.

5. The wiring board according to claim 2 , wherein the extension suppressing portion is formed such that the end portion in the width direction protrudes toward the main body portion side more than the center portion in the width direction in a region on the main body portion side where the rigid layer is not present.

6. The wiring board according to claim 2 , wherein the folded portion protrudes outward in the width direction beyond the tail portion main body, forming a gap between the folded portion and an edge of the laminate.

7. The extension suppression portion forms an extension region that extends outward in the width direction of the tail portion main body when the folded-back portion is unfolded, The wiring board according to claim 1 , wherein the extension suppression portion is formed by folding the extension region so that the extension region overlaps a second surface of the base material opposite to the first surface.

8. The wiring board according to claim 7 , wherein the extension suppressing portion is formed by bonding the extension region of the base material to the second surface of the base material without an adhesive layer therebetween.

9. The wiring board according to claim 1 , wherein the base material is made of a silicone elastomer.

10. a step of forming a conductive layer by screen printing on a first surface of a base material before cutting out a substrate having a sheet-like main body portion and a tail portion extending from one end of the main body portion with a width narrower than that of the main body portion in a plan view; forming a protective layer on the conductive layer by screen printing; a step of cutting out an extension region that extends outward in the width direction of the tail portion main body on the width direction outer side of a boundary region between the main body portion and the tail portion defined on the tail portion; and a step of folding and joining the cut-out extension region toward the tail portion main body to form an extension suppression portion that overlaps with the boundary region.

Images