Stretchable device

Abstract

Provided is a stretchable device comprising: a stretchable substrate; stretchable wiring disposed on a main surface of the stretchable substrate; an electronic component electrically connected to the stretchable wiring; a first stretchable covering layer covering the stretchable wiring; and a protective resin covering the electronic component. The stretchable device is provided with an overlapping region in which the protective resin and a portion of the first stretchable covering layer overlap when viewed from the thickness direction of the stretchable substrate. The overlapping region is positioned at least over the stretchable wiring when viewed from the thickness direction. In the overlapping region, the overlapping width between the first stretchable covering layer and the protective resin is greater than the thickness of the first stretchable covering layer.

Description

stretchable devices

[0001] The present disclosure relates to stretchable devices.

[0002] Stretchable devices including a stretchable substrate have been known for some time. Stretchable devices can be used in, for example, living organisms or devices that require stretchability.

[0003] Japanese Patent Application Laid-Open No. 2000-156589

[0004] In stretchable devices, electronic components such as sensors may be mounted on a stretchable substrate. For example, as in the printed circuit board of Patent Document 1, when mounting electronic components on a substrate, a protective resin may be provided to cover the electronic components in order to prevent the electronic components from falling off. The present inventors have found that there is room for improvement in the mounting reliability of electronic components when applying such a protective resin to a stretchable device.

[0005] In a stretchable device, a stretchable substrate provided with electronic components and a stretchable wiring connected to the electronic components are stretchable, while general electronic components are not stretchable. Therefore, particularly when the stretchable device is stretched, stress acting due to the difference in stretchability between the electronic components and the stretchable wiring may induce damage to the stretchable wiring near the electronic components and / or detachment of the electronic components. For this reason, in a structure in which electronic components are provided in a stretchable device, particular importance may be placed on the mounting reliability of the electronic components on stretchable members such as stretchable wiring.

[0006] The present disclosure has been made in view of the above-mentioned problems. That is, a main object of the present disclosure is to provide a stretchable device that has excellent mounting reliability for electronic components.

[0007] The present inventors have invented a stretchable device that achieves the above-mentioned main object.

[0008] A stretchable device according to one embodiment of the present disclosure comprises a stretchable substrate, stretchable wiring arranged on a main surface of the stretchable substrate, an electronic component electrically connected to the stretchable wiring, a first stretchable covering layer covering the stretchable wiring, and a protective resin covering the electronic component; the stretchable device comprises an overlapping region in which the protective resin and a portion of the first stretchable covering layer overlap when viewed in the thickness direction of the stretchable substrate; the overlapping region is positioned so as to overlap at least the stretchable wiring when viewed in the thickness direction; and in the overlapping region, the overlap width between the first stretchable covering layer and the protective resin is greater than the thickness of the first stretchable covering layer.

[0009] According to one embodiment of the present disclosure, a stretchable device with excellent mounting reliability for electronic components is provided.

[0010] FIG. 1 is a plan view of a stretchable device according to a first embodiment of the present disclosure. FIG. 2 is a cross-sectional view schematically showing the A-A cross section of the stretchable device shown in FIG. 1. FIG. 3 is a plan view schematically showing a stretchable device according to a modified version of the first embodiment of the present disclosure. FIG. 4 is a cross-sectional view schematically showing the B-B cross section of the stretchable device shown in FIG. 3. FIG. 5 is a plan view schematically showing a stretchable device according to a modified version of the first embodiment of the present disclosure. FIG. 6 is a cross-sectional view schematically showing the B-B cross section of the stretchable device shown in FIG. 5. FIG. 7 is a plan view schematically showing a stretchable device according to a second embodiment of the present disclosure. FIG. 8 is a cross-sectional view schematically showing the A-A cross section of the stretchable device shown in FIG. 7. FIG. 9 is a cross-sectional view schematically showing the B-B cross section of the stretchable device shown in FIG. 7. FIG. 10 is a plan view schematically showing a stretchable device according to a modified version of the second embodiment of the present disclosure. FIG. 11 is a cross-sectional view schematically showing the A-A cross section of the stretchable device shown in FIG. 10. Fig. 12 is a cross-sectional view schematically showing a cross section B-B of the stretchable device shown in Fig. 10. Fig. 13 is a plan view schematically showing a stretchable device according to a modified version of the second embodiment of the present disclosure. Fig. 14 is a cross-sectional view schematically showing a cross section B-B of the stretchable device shown in Fig. 13. Fig. 15 is a cross-sectional view schematically showing a stretchable device according to a third embodiment of the present disclosure. Fig. 16 is a cross-sectional view schematically showing a stretchable device according to a modified version of the third embodiment of the present disclosure. Fig. 17 is a cross-sectional view schematically showing a stretchable device according to a modified version of the third embodiment of the present disclosure. Fig. 18 is a plan view schematically showing a stretchable device according to a modified version of the third embodiment of the present disclosure.

[0011] The following describes specific embodiments of the present disclosure. The applicant provides the following description and examples to enable those skilled in the art to fully understand the present disclosure, and it should be noted that these are not intended to limit the subject matter described in the claims. In other words, the present disclosure is not particularly limited to the preferred embodiments described below, and can be implemented with appropriate modifications within the scope of its purpose. For convenience, the present disclosure may be divided into embodiments and examples, etc., in consideration of ease of explanation or understanding of the main points. However, partial substitution and / or combination of the configurations shown in different embodiments, etc. is possible. In describing such embodiments, redundant explanations of substantially identical matters may be omitted, and only differences may be described. In particular, similar actions and effects resulting from similar configurations may not be mentioned in each embodiment.

[0012] In this specification, the terms "thickness direction of the stretchable device," "thickness direction of the stretchable substrate," and "stacking direction of the stretchable substrate" may be used interchangeably. This direction corresponds to direction Y in the drawings.

[0013] As used herein, the terms "cross-sectional view" and "cross-sectional shape" refer to the form captured from a direction approximately perpendicular to the thickness direction Y of the stretchable device (in short, the form when cut along a plane parallel to the thickness direction Y of the stretchable device). Furthermore, as used herein, the term "plan view" refers to a sketch of an object viewed from above or below along the thickness direction Y of the stretchable device.

[0014] Furthermore, in this specification, "above" an element includes not only the case of contacting the top surface of the element, but also the case of not contacting the top surface of the element. In other words, "above" an element does not only mean above the element, i.e., a position above the element via another object or a position above with a gap, but also a position directly above the element. Furthermore, "above" does not necessarily mean above in the vertical direction. "Above" merely indicates the relative positional relationship of an element.

[0015] The various numerical ranges referred to herein are intended to include the lower and upper numerical limits themselves unless otherwise specified, and the term "about" means that there may be a variation or difference of a few percent, e.g., ±10%.

[0016] As used herein, "vertical" and "substantially vertical" do not necessarily mean completely "vertical," but include aspects that are slightly deviated from the completely vertical (for example, a range of ±10°, e.g., ±5°, from the completely vertical).

[0017] Furthermore, in this specification, "substantially parallel" does not necessarily mean completely "parallel," but includes a state where the parallelism is slightly deviated from the parallelism (for example, within a range of ±10° from completely parallelism, e.g., within a range of ±5°).

[0018] [Basic configuration of stretchable device] The structure of a stretchable device will be described with reference to Figures 1 and 2. Figure 1 is a plan view illustrating an example of a stretchable device according to an embodiment of the present disclosure. Figure 2 is a cross-sectional view schematically illustrating the A-A cross section of the stretchable device 1A shown in Figure 1. The A-A cross section is a cross section obtained by cutting the stretchable device 1A along the extension direction of the stretchable wiring 20, and is a cross section parallel to the thickness direction Y of the stretchable device.

[0019] The stretchable device 1A includes a stretchable substrate 10. A stretchable wiring 20 is disposed on a main surface 12 of the stretchable substrate 10. At least a portion of the stretchable wiring 20 may be covered with a stretchable covering layer 40. An electronic component 30 is mounted on the main surface 12 of the stretchable substrate 10 and is electrically connected to the stretchable wiring 20. A protective resin 50 is provided on the electronic component 30. The protective resin 50 may cover the electronic component 30 mounted on the main surface 12 of the stretchable substrate 10.

[0020] Here, the "principal surface 12 of the stretchable substrate 10" refers to a surface extending in a direction different from the thickness direction Y of the stretchable substrate 10, and means, for example, a surface extending in a direction Z-X that is approximately perpendicular to the thickness direction Y of the stretchable substrate 10. The "principal surface 12" corresponds to a surface that is clearly larger in area than other surfaces of the sheet-like stretchable substrate 10 (for example, side surfaces extending approximately parallel to the thickness direction Y). The sheet-like or film-like stretchable substrate 10 may extend along the stretch direction of the stretchable device 1A. In such a structure, the principal surface 12 of the stretchable substrate 10 can also be interpreted as a surface that extends along the stretch direction of the stretchable substrate 10. The principal surface 12 can also be interpreted as a surface that extends along the extension direction of the stretchable wiring 20. Note that, although the drawings show a stretchable device extending in a specific direction for clarity, the shape of the stretchable device is not particularly limited. For example, the shape of the stretchable device 1A in plan view can be a quadrilateral (e.g., square, rectangle, etc.), a polygon such as a triangle, a circle, an ellipse, a semicircle, a crescent, or an irregular shape, etc.

[0021] Below, the main components included in the stretchable device 1A of the present disclosure will be described with reference to FIGS. 1 and 2.

[0022] (Stretchable Substrate 10) The stretchable substrate 10 (hereinafter also simply referred to as "substrate") may be a sheet-like or film-like stretchable substrate, and may be made of, for example, a stretchable resin material. In this specification, "stretchability" simply means the property of being able to stretch and contract, and can also be referred to as stretchability, stretchable, etc. More specifically, it means the property of being able to stretch from a non-stretched state, which is the normal state in which no tensile stress is applied, by applying tensile stress, and being able to contract when released from the stretched state. Although only one stretchable substrate 10 is shown in the drawings, one or more additional stretchable substrates may be laminated in the stretchable device.

[0023] A stretchable resin material may be used as the stretchable substrate 10. Although this is merely an example, the stretchable substrate 10 preferably includes at least one selected from the group consisting of an olefin-based resin elastomer, a urethane-based resin elastomer, and a silicone-based resin elastomer. When the stretchable device 1A includes multiple stretchable substrates 10, each of the multiple stretchable substrates 10 may be made of the same material or may be made of different materials.

[0024] Although the thickness of the stretchable substrate 10 is not particularly limited, when prioritizing the stretchability of the device, it is preferably 1 mm or less, and more preferably 70 μm or less. When the stretchable device is attached to a living body, when prioritizing the viewpoint of suppressing inhibition of stretching of the surface of the living body, it is preferably 100 μm or less, and more preferably 70 μm or less. Furthermore, when prioritizing the mechanical strength of the device, the thickness of the stretchable substrate is preferably 10 μm or more, or 20 μm or more. Furthermore, when the stretchable device 1A includes multiple stretchable substrates 10, each of the multiple stretchable substrates may have the same thickness or may have thicknesses different from each other.

[0025] (Stretchable Wiring 20) A stretchable wiring 20 (hereinafter also simply referred to as "wiring") is arranged on the main surface 12 of the stretchable substrate 10. The stretchable wiring 20 may be a mixture of conductive particles and a resin. For example, at least one type of metal powder selected from the group consisting of Ag (silver), Cu (copper), and Ni (nickel) can be used as the conductive particles. The average particle size of the conductive particles is not particularly limited, but is preferably 0.01 μm or more and 10 μm or less. The shape of the conductive particles is also not particularly limited, but is preferably, for example, approximately spherical. Alternatively, from the viewpoint of improving stretchability, the shape of the conductive particles can be an irregular shape such as a substantially elliptical, polyhedral, flat, or a shape with protrusions. The resin mixed with the conductive particles may be, for example, at least one resin selected from the group consisting of epoxy-based resins, urethane-based resins, acrylic-based resins, and silicone-based resins. The stretchable device 1A may include a plurality of stretchable wirings 20. Each of the multiple stretchable wires 20 may be made of the same material, or may be made of different materials.

[0026] The thickness of the stretchable wiring 20 is preferably 100 μm or less, and more preferably 50 μm or less. Furthermore, when emphasis is placed on the mechanical strength of the stretchable wiring 20, the thickness of the stretchable wiring 20 is preferably 1 μm or more.

[0027] The stretchable wiring 20 may extend in any direction. The stretchable wiring 20 may extend along the extension direction of the main surface of the stretchable substrate 10. When viewed from the thickness direction Y of the stretchable substrate 10, the stretchable wiring 20 does not necessarily have to be arranged in a straight line, and may be arranged, for example, in a curved line. Furthermore, when viewed from the thickness direction Y, the stretchable wiring 20 does not necessarily have to extend in one direction. For example, the stretchable wiring 20 may branch out from a single wire into multiple wires. The number of stretchable wirings 20 arranged on the stretchable substrate 10 is not particularly limited, and one or multiple wires 20 may be arranged.

[0028] The stretchable wiring 20 does not necessarily have to be disposed on only one main surface of the stretchable substrate 10. For example, the stretchable wiring 20 may be disposed on each of both main surfaces of the stretchable substrate 10.

[0029] (Stretchable covering layer 40) The stretchable covering layer 40 covers at least a portion of the stretchable wiring 20 arranged on the main surface 12 of the stretchable substrate 10. For example, the stretchable covering layer 40 may cover the stretchable wiring 20 except for the connection portion between the stretchable wiring 20 and the electronic component 30. At least a portion of the stretchable wiring 20 may be surrounded by the stretchable substrate 10 and the stretchable covering layer 40. This allows the stretchable wiring 20 to be protected from the outside.

[0030] For example, the stretchable covering layer 40 may be disposed only on and near the stretchable wire 20 (see FIG. 1). Alternatively, the stretchable covering layer 40 may be disposed only on at least the stretchable wire 20. The stretchable covering layer 40 may be disposed along the extension direction of the stretchable wire 20. Alternatively, as shown in FIG. 3, the stretchable covering layer 40 may be disposed from above the stretchable wire 20 to across the main surface 12 of the stretchable substrate 10. In other words, the stretchable covering layer 40 may cover the stretchable wire 20 and extend so as to overlap with the stretchable substrate 10 across the entire stretchable substrate 10 when viewed from the thickness direction Y.

[0031] For example, when a plurality of stretchable wires 20 are arranged on the stretchable substrate 10, each of the plurality of stretchable wires 20 may be separately covered by a plurality of stretchable covering layers 40. Alternatively, the plurality of stretchable wires 20 may be integrally covered by a single stretchable covering layer 40.

[0032] A stretchable resin material may be used as the stretchable covering layer 40. Although merely an example, the stretchable covering layer 40 preferably includes at least one resin selected from the group consisting of olefin-based resins, urethane-based resins, silicone-based resins, and acrylic-based resins. When the stretchable device 1A includes multiple stretchable covering layers 40, each of the multiple stretchable covering layers 40 may be made of the same material or different materials. Furthermore, the stretchable covering layers 40 may be made of the same material as the stretchable substrate 10 or different materials.

[0033] Although the thickness of the stretchable covering layer 40 is not particularly limited, if emphasis is placed on the stretchability of the device, it is preferably 100 μm or less, and more preferably 70 μm or less. Furthermore, if emphasis is placed on the mechanical strength of the device, the thickness of the stretchable covering layer 40 is preferably 10 μm or more, or 20 μm or more. Furthermore, when the stretchable device 1A includes multiple stretchable covering layers 40, each of the multiple stretchable covering layers 40 may have the same thickness or may have thicknesses different from each other.

[0034] (Electronic component 30) An electronic component 30 electrically connected to the stretchable wiring 20 may be provided on the main surface 12 of the stretchable substrate 10. As shown in FIG. 2 , the electronic component 30 may be electrically connected to one end 25 of the stretchable wiring 20 arranged on the main surface 12 of the stretchable substrate 10. The electronic component 30 and the stretchable wiring 20 may be electrically connected to each other via a conductive connecting part 60. As the connecting part 60, for example, solder may be used. The structure of the electronic component 30 is not particularly limited, but for example, the electronic component 30 may be provided with an external electrode 32 as shown in FIG. 2 . When the electronic component 30 is provided with the external electrode 32, the external electrode 32 and the stretchable wiring 20 may be electrically connected via the connecting part 60. Alternatively, the stretchable device may not be provided with the connecting part 60, and the stretchable wiring 20 and the electronic component 30 may be electrically connected by direct contact.

[0035] The electronic components 30 mounted on the stretchable device 1A are not particularly limited, and examples thereof include passive components such as capacitors, resistors, and inductors, active components such as amplifiers and rectifiers, and sensor components such as acceleration sensors and temperature sensors. The stretchable device 1A can include one or more electronic components 30. When the stretchable device 1A includes a plurality of electronic components 30, a plurality of the same electronic components 30 may be provided, or a plurality of electronic components 30 of different types may be provided.

[0036] (Protective Resin 50) The electronic component 30 may be covered with the protective resin 50. As shown in FIG. 2, the electronic component 30 may be sealed on the main surface 12 of the stretchable substrate 10 by being covered with the protective resin 50. Due to this structure, the protective resin 50 may also be referred to as, for example, a "sealing resin." The protective resin 50 can function as a barrier layer that insulates the electronic component 30 from the external environment and prevents foreign matter such as moisture from penetrating the electronic component 30. This can prevent deterioration of the characteristics of the electronic component 30.

[0037] The protective resin 50 may be made of an insulating resin material with a high Young's modulus from the viewpoint of suitably protecting the electronic component 30. Specifically, the protective resin 50 may be made of a resin material having a higher Young's modulus than the stretchable substrate 10. As the material of the protective resin 50, for example, at least one selected from the group consisting of an acrylic resin, an epoxy resin, an olefin resin, a urethane resin, and a styrene-butadiene resin may be used.

[0038] The electronic component 30 may have inferior stretchability compared to components such as the stretchable substrate 10 and the stretchable wiring 20. Due to this difference in stretchability, there is a risk that the electronic component 30 will detach when the stretchable device is stretched. Furthermore, stress is likely to concentrate on the stretchable wiring 20 at the connection interface with electronic components 30 that have different stretchability, which may result in damage such as cracks in the stretchable wiring 20 and lead to disconnection. In view of these issues, the present inventors have invented a stretchable device that uses a novel structure described below to suitably maintain the connection state between the stretchable wiring 20 and the electronic component 30 and has excellent mounting reliability for the electronic component 30.

[0039] First Embodiment Based on the details of the main components of the stretchable device described above, the following describes the characteristic parts of a stretchable device 1A according to a first embodiment of the present disclosure.

[0040] As shown in FIGS. 1 and 2 , in the stretchable device 1A of the present disclosure, the protective resin 50 that covers the electronic component 30 extends onto the stretchable covering layer 40 that covers the stretchable wiring 20. When viewed from the thickness direction Y of the stretchable substrate 10, the stretchable device 1A includes an overlapping region 52 in which the protective resin 50 and a portion of the stretchable covering layer 40 overlap. When viewed from the thickness direction Y, the overlapping region 52 is positioned so as to overlap at least the stretchable wiring 20. In other words, when viewed from the thickness direction Y, the protective resin 50 and the stretchable covering layer 40 may overlap at least on the stretchable wiring 20. The overlapping region 52 can be interpreted as a region having an overlapping portion where the protective resin 50 and a portion of the stretchable covering layer 40 overlap each other. When viewed from the thickness direction Y, the overlapping portion may be located at least on the stretchable wiring 20.

[0041] In the above-described structure, the protective resin 50 may cover not only the electronic component 30 but also the connection portion between the electronic component 30 and the stretchable wiring 20. In other words, the protective resin 50 may integrally cover the electronic component 30, the connection portion between the electronic component 30 and the stretchable wiring 20, and a portion of the stretchable covering layer 40. The protective resin 50 may be in contact with the main surface 42 of the stretchable covering layer 40 located on the opposite side from the stretchable wiring 20. The protective resin 50 may be adhered to the main surface 42 of the stretchable covering layer 40.

[0042] Furthermore, as will be described later, the overlapping region 52 may extend from a region that overlaps with a portion of the stretchable wiring 20 when viewed from the thickness direction Y to a region that does not overlap with the stretchable wiring 20 (see FIG. 3 ). Hereinafter, for convenience of explanation, the region where the stretchable wiring 20, the stretchable covering layer 40, and the protective resin 50 overlap in the thickness direction Y will be referred to as a first overlapping region 52a, and the region where the stretchable covering layer 40 and the protective resin 50 overlap without overlapping with the stretchable wiring 20 will be referred to as a second overlapping region 52b. The stretchable device 1A of the present disclosure includes at least the first overlapping region 52a.

[0043] As shown in FIG. 2 , the protective resin 50 may extend from the edge 46 of the stretchable covering layer 40 located on the electronic component 30 side in the thickness direction Y toward the normal direction of the edge 46, so as to extend onto the main surface 42 of the stretchable covering layer 40 by a distance d. The distance d corresponds to the width dimension of the overlapping region along the normal direction of the edge 46 of the stretchable covering layer 40. The distance d can also be interpreted as the width of the overlapping portion between the stretchable covering layer 40 and the protective resin 50 in a cross-sectional view. Such distance d can also be referred to as the overlap width, overlap distance, or overlap width between the stretchable covering layer 40 and the protective resin 50. In other words, the stretchable covering layer 40 and the protective resin 50 may be arranged to overlap by the width d when viewed in the thickness direction Y. Note that, as shown in FIG. 2 , the width dimension of the overlapping region is the dimension in the direction in which the stretchable wiring connected to the electronic component 30 faces each other. Furthermore, if the overlapping area is not uniform, the distance d in the overlapping area is the maximum value along the normal direction of the edge 46 of the stretchable covering layer 40 .

[0044] At least in the first overlap region 52a, the overlap width d is greater than the thickness T1 of the stretchable covering layer 40 (see FIG. 2 ). In other words, in the first overlap region 52a, the thickness T1 of the stretchable covering layer 40 is smaller than the overlap width d between the stretchable covering layer 40 and the protective resin 50. In this specification, the "thickness T1 of the stretchable covering layer 40" corresponds to the maximum thickness of the stretchable covering layer 40 in the overlap region 52 between the stretchable covering layer 40 and the protective resin 50.

[0045] In a stretchable device, a region where the protective resin 50 is present may have inferior stretchability compared to a region where the protective resin 50 is not present. Although there are no particular limitations on the upper limit of the overlap width d, it is desirable that it be, for example, 3 mm or less from the viewpoint of preventing an excessive decrease in the stretchability of the entire device.

[0046] As described above, in the stretchable device 1A of the present disclosure, the protective resin 50 covers the electronic component 30 and extends onto the stretchable coating layer 40, thereby forming an overlap region 52 that partially overlaps with the stretchable coating layer 40. In this case, because the overlap width d between the stretchable coating layer 40 and the protective resin 50 is greater than the thickness T1 of the stretchable coating layer 40, the protective resin 50 can bond over a wide area with the stretchable coating layer 40 located around the electronic component 30. This allows the protective resin 50 and the stretchable coating layer 40 to be more firmly bonded, thereby allowing the electronic component 30 covered by the protective resin 50 to be suitably fixed on the stretchable substrate 10. In other words, in addition to protecting the electronic component 30, the protective resin 50 can also help fix the electronic component 30 to the stretchable substrate 10.

[0047] The effect of fixing the electronic component 30 by such a protective resin 50 can be particularly effective in a stretchable device. Stretchable members such as the stretchable substrate 10, stretchable wiring 20, and stretchable coating layer 40 that constitute a stretchable device can expand and contract when the stretchable device is in use. On the other hand, the electronic component 30 is generally made of a member that is difficult to expand and contract, and therefore does not easily follow the expansion and contraction of the stretchable device. Therefore, there is a risk that the electronic component 30 will detach from the stretchable device when the stretchable device expands and contracts. Furthermore, due to differences in stretchability, stress may concentrate on the stretchable wiring 20 near the connection portion with the electronic component 30, which may cause damage to the stretchable wiring 20 and ultimately lead to disconnection.

[0048] The stretchable device 1A of the present disclosure includes an overlap region 52 where the protective resin 50 and the stretchable covering layer 40 overlap. This allows the protective resin 50 to extend to the stretchable covering layer 40 located around the electronic component 30, thereby covering the electronic component 30 over a wide area. As described above, the protective resin 50 has a higher Young's modulus than the stretchable substrate 10. That is, the protective resin 50 is less stretchable than the stretchable substrate 10. Therefore, in the stretchable device, the region covered by the protective resin 50 has reduced stretchability compared to the uncovered region. This means that the presence of the protective resin 50 reduces the stretchability of the stretchable device in the region around the electronic component 30. This reduces the difference in stretchability between the stretchable member and the electronic component 30 around the electronic component 30. As a result, detachment of the electronic component 30 due to expansion and contraction of the stretchable device 1A can be suitably suppressed.

[0049] Furthermore, the overlapping region 52 between the stretchable covering layer 40 and the protective resin 50 is positioned at least at a position overlapping with the stretchable wiring 20 when viewed from the thickness direction Y. In such a structure, the protective resin 50 covers the connection portion between the electronic component 30 and the stretchable wiring 20. As a result, the protective resin 50 can also contribute to protecting the connection portion between the electronic component 30 and the stretchable wiring 20, which may be the starting point for disconnection of the stretchable wiring 20.

[0050] Furthermore, according to the above-described structure, the stretchability decreases in the vicinity of the connection portion between the stretchable wiring 20 and the electronic component 30, which overlaps with the protective resin 50 in the thickness direction Y. This can mitigate a sudden decrease in the stretchability of the stretchable wiring 20 in the connection portion with the electronic component 30. Therefore, the difference in stretchability of the stretchable wiring 20 between the connection portion with the electronic component 30 and other portions is reduced, and stress concentration on the stretchable wiring 20 at and near the connection portion can be reduced. As a result, damage and disconnection of the stretchable wiring 20 in the vicinity of the connection portion with the electronic component 30 can be suitably suppressed.

[0051] As described above, the stretchable device 1A of the present disclosure can suppress detachment of the electronic component 30, and can also suppress damage and disconnection of the stretchable wiring 20 near the connection portion with the electronic component 30. Therefore, according to the present disclosure, a stretchable device 1A can be provided in which the electronic component 30 is suitably fixed and has excellent connection reliability between the electronic component 30 and the stretchable wiring 20, and is suitable in terms of mounting reliability of the electronic component 30.

[0052] As shown in FIGS. 1 and 2 , the overlap region 52 may be a region where the periphery 55 of the protective resin 50 and the periphery 45 of the stretchable covering layer 40 overlap when viewed from the thickness direction Y. The peripheries of the stretchable covering layer 40 and the protective resin 50 may overlap each other in at least a portion when viewed from the thickness direction Y. In this specification, the "periphery" of a certain member refers to the periphery of the member when viewed from the thickness direction Y. Specifically, it refers to a band-shaped region that includes and extends along the edge of the member. The periphery 55 of the protective resin 50 may be positioned so that the periphery 45 of the stretchable covering layer 40 rides on the main surface 42 of the stretchable covering layer 40. In the overlap region 52, the edge 46 of the stretchable covering layer 40 may be positioned closer to the electronic component 30 than the edge 56 of the protective resin 50. In the overlap region 52, the periphery 45 of the stretchable covering layer 40 may be covered by the protective resin 50. In a cross-sectional view, the periphery 45 of the stretchable covering layer 40 may be located between the protective resin 50 and the stretchable substrate 10, and / or between the protective resin 50 and the stretchable wiring 20. In such a structure, the overlap width d in the overlap region 52 corresponds to the distance from the edge 46 of the stretchable covering layer 40 to the edge 56 of the protective resin 50.

[0053] The above-described structure makes it possible to prevent the peripheral edge 45 of the stretchable covering layer 40 from peeling off from the stretchable substrate 10 and / or the stretchable wiring 20. That is, in the stretchable device 1A of the present disclosure, the protective resin 50 can contribute to improving the mounting reliability of the electronic component 30, as well as improving the peel resistance of the stretchable covering layer that covers the stretchable wiring.

[0054] The stretchable wiring 20 may be covered with a stretchable covering layer 40 in an area excluding the connection portion with the electronic component 30 and the surrounding area. As shown in FIG. 2 , the stretchable covering layer 40 may be positioned on the main surface 12 of the stretchable substrate 10 at a distance from the electronic component 30. On the main surface 12 of the stretchable substrate 10, around the electronic component 30, there may be an area 54 where the stretchable covering layer 40 is not positioned. This area 54 can also be referred to as, for example, an uncovered area. The protective resin 50 may extend from above the electronic component 30 across the uncovered area 54 and reach onto the main surface 42 of the stretchable covering layer 40.

[0055] In the cross-sectional view shown in FIG. 2 , the protective resin 50 may be recessed toward the stretchable substrate 10 side so as to fill the uncovered region 54. The protective resin 50 may have a cross-sectional structure that bites into the stretchable wiring 20 in the uncovered region 54 between the electronic component 30 and the stretchable covering layer 40. Such a biting structure exerts an anchor effect on the protective resin 50, which can improve the adhesion of the protective resin 50 to the stretchable device. By covering the electronic component 30 with such a protective resin 50 with excellent adhesion, the electronic component 30 can be more suitably fixed to the stretchable device.

[0056] As shown in FIG. 2 , in the uncovered region 54, the protective resin 50 may be in contact with the stretchable wiring 20 located between the electronic component 30 and the stretchable covering layer 40. In the uncovered region 54, the protective resin 50 may be in contact with the connection portion between the stretchable wiring 20 and the electronic component 30, and with the stretchable wiring 20 extending from the connection portion toward the stretchable covering layer 40. With such a structure, the protective resin 50 can improve the mechanical strength of the stretchable wiring 20 around the connection portion with the electronic component 30. Furthermore, contact between the protective resin 50 and the stretchable wiring 20 can reduce the stretchability of the stretchable wiring 20 near the connection portion with the electronic component 30, thereby reducing the difference in stretchability. This makes it possible to suitably suppress damage and disconnection of the stretchable wiring 20 caused by stress concentration due to the difference in stretchability.

[0057] The stretchable covering layer 40 may have an end surface 44. The end surface 44 is a surface extending in a different direction from the main surface 42 and corresponds to the surface facing the electronic component 30. The protective resin 50 that has entered the uncovered region 54 may be in contact with the end surface 44 of the stretchable covering layer 40. The stretchable covering layer 40 may be in contact with the protective resin 50 at both the main surface 42 and the end surface 44. The contact area between the stretchable covering layer 40 and the protective resin 50 may be continuous from the end surface 44 of the stretchable covering layer 40 to the main surface 42. The stretchable covering layer 40 may be in contact with the protective resin 50 across two surfaces extending in different directions. This structure improves adhesion between the protective resin 50 and the stretchable covering layer 40. This improves the peel resistance of the protective resin 50, and therefore the peel resistance of the electronic component 30 covered by the protective resin 50 may be improved. The protective resin 50 may be in contact with a portion of the end surface 44 of the stretchable covering layer 40 or may be in contact with the entire end surface 44 .

[0058] As shown in Fig. 2, the electronic component 30 and the stretchable wiring 20 may be electrically connected via a connection portion 60. When viewed from the thickness direction Y, the connection portion 60 and the stretchable covering layer 40 may be spaced apart. A separation region 53 that is spaced apart from each other may exist between the connection portion 60 and the stretchable covering layer 40. The protective resin 50 may extend over the separation region 53 onto the stretchable covering layer 40. This allows the connection portion between the electronic component 30 and the connection portion 60 and / or the connection portion between the connection portion 60 and the stretchable wiring 20 to be suitably protected by the protective resin.

[0059] The protective resin 50 may be located in the separation region 53. The protective resin 50 may be present between the connection portion 60 and the stretchable covering layer 40. The protective resin 50 may be in contact with the connection portion 60. Preferably, the protective resin 50 is in contact with the stretchable wiring 20 in the separation region 53. With this structure, the protective resin 50 can improve the mechanical strength of the stretchable wiring 20 around the connection portion with the electronic component 30. This makes it possible to suitably suppress damage and disconnection of the stretchable wiring 20.

[0060] Furthermore, a conductive adhesive may be used as the connection part 60 that electrically connects the stretchable wiring 20 and the electronic component 30. In other words, a conductive adhesive may be interposed between the electronic component 30 and the stretchable wiring 20, and the electronic component 30 and the stretchable wiring 20 may be electrically connected by the conductive adhesive.

[0061] By using a conductive adhesive as the connecting part 60, the electronic component 30 and the stretchable wiring 20 can be connected at a lower temperature than when solder is used. Therefore, even if the heat resistance temperature of components such as the stretchable substrate 10, the stretchable wiring 20, and the electronic component 30 is low, the electronic component 30 can be mounted without damaging these components. This makes it possible to provide a stretchable device with excellent mounting reliability for the electronic component 30.

[0062] As the conductive adhesive, a known conductive adhesive can be used. For example, the conductive adhesive may be composed of a resin-based adhesive and a conductive filler dispersed in the resin-based adhesive. As the resin-based adhesive, for example, at least one selected from the group consisting of epoxy-based thermosetting resins, vinyl-based thermosetting resins, acrylic-based thermosetting resins, urethane-based thermosetting resins, imide-based thermosetting resins, and silicone-based thermosetting resins can be used.

[0063] The conductive filler may be, for example, a conductive particle in which a core material such as a resin is covered with a metal film. The metal film is not particularly limited, but may be, for example, at least one material selected from the group consisting of Ni (nickel), Au (gold), Ag (silver), Cu (copper), Al (aluminum), and Ti (titanium). Alternatively, the conductive filler may be at least one material selected from the group consisting of Ni, Au, Ag, Cu, Al, Ti, C (carbon), and Si (silicon) processed into particles.

[0064] (Modifications of First Embodiment) The stretchable device 1A according to the first embodiment can be modified in various ways. Figures 3 and 4 are cross-sectional views schematically showing a stretchable device 1B according to a modification of the first embodiment.

[0065] As shown in Fig. 3, the stretchable covering layer 40 may integrally cover a plurality of stretchable wirings 20 arranged on the main surface 12 of the stretchable substrate 10. The stretchable covering layer 40 may continuously cover a plurality of stretchable wirings 20 on the main surface 12 of the stretchable substrate 10. The stretchable covering layer 40 may have an opening 47 at the location where the electronic component 30 is placed. In other words, the stretchable covering layer 40 may have an opening 47 that penetrates in the thickness direction Y, and the electronic component 30 may be mounted in the opening 47. The stretchable wiring 20 may extend towards the electronic component 30 arranged in the opening 47, and be electrically connected to the electronic component 30 at the opening 47.

[0066] At least a portion of the opening edge 48 that defines the opening 47 may overlap with the protective resin 50 when viewed from the thickness direction Y. The protective resin 50 may be disposed so as to cover the electronic component 30 and the opening 47. The protective resin 50 may extend to close the opening 47. When viewed from the thickness direction Y, the protective resin 50 may overlap with the periphery 45 of the stretchable covering layer 40 that surrounds the opening 47 (see FIGS. 3 and 4 ). The protective resin 50 may be in contact with the periphery 45 that extends along the opening edge 48 that defines the opening 47.

[0067] FIG. 4 is a cross-sectional view schematically illustrating the B-B cross section of the stretchable device 1B shown in FIG. 3. The B-B cross section is a cross section cut along a direction X intersecting the extension direction Z of the stretchable wiring 20, and corresponds to a cross section of a region where the stretchable wiring 20 is not disposed. As shown in FIG. 4, the protective resin 50 and the stretchable covering layer 40 may overlap by an overlap width d when viewed from the thickness direction Y, thereby forming an overlap region 52. The protective resin 50 may extend from the opening 47 so as to ride onto the main surface 42 of the stretchable covering layer 40. In this manner, an overlap region 52 (i.e., a second overlap region 52b) between the protective resin 50 and the stretchable covering layer 40 may be formed in a region that does not overlap with the stretchable wiring 20 when viewed from the thickness direction Y. In the second overlap region 52b, the overlap width d between the electronic component 30 and the stretchable covering layer 40 may be greater than the thickness T1 of the stretchable covering layer 40. By providing such a second overlapping region 52b, the adhesion of the protective resin 50 can be improved.

[0068] 3 , a first overlapping region 52a positioned in a region overlapping with the stretchable wiring 20 as viewed in the thickness direction Y, and a second overlapping region 52b positioned in a region not overlapping with the stretchable wiring 20, may be continuous. In other words, the overlapping region 52 between the protective resin 50 and the stretchable covering layer 40 may extend continuously from the region 52a overlapping with the stretchable wiring 20 as viewed in the thickness direction Y to the region 52b not overlapping with the stretchable wiring 20. For example, as viewed in the thickness direction Y, the protective resin 50 and the stretchable covering layer 40 may overlap each other over the entire periphery of the opening 47. In other words, the overlapping region 52 may extend in a band shape along the opening edge 48 that defines the opening 47. This structure allows the protective resin 50 and the stretchable covering layer 40 to be bonded over a wide area, thereby improving the adhesion of the protective resin 50.

[0069] Furthermore, in a cross-sectional view, the protective resin 50 may be embedded in the opening 47 (see FIG. 4 ). At the opening 47, the protective resin 50 may be in contact with the main surface 12 of the stretchable substrate 10. That is, the protective resin 50 may be in contact with both the stretchable substrate 10 and the stretchable coating layer 40. With this structure, a stretchable device having superior peel resistance of the protective resin 50 can be obtained.

[0070] Fig. 5 is a plan view schematically showing a stretchable device 1C according to another modified example of the first embodiment. Fig. 6 is a cross-sectional view schematically showing the cross section BB of the stretchable device 1C shown in Fig. 5.

[0071] As shown in the figure, a part of the opening edge 48 that defines the opening 47 may not overlap with the stretchable wiring 20 and the protective resin 50 when viewed from the thickness direction Y. In other words, the opening edge 48 that defines the opening 47 may overlap with the protective resin 50 in some regions when viewed from the thickness direction Y, while not overlapping with the stretchable wiring 20 and the protective resin 50 in other regions. In such a structure, the opening 47 may have an opening region that extends so as to protrude from the protective resin 50 in the region that does not overlap with the stretchable wiring 20.

[0072] 5 , when viewed from the thickness direction Y, the opening edge 48 may include an overlapping portion 48A that overlaps with the protective resin 50 and a non-overlapping portion 48B that does not overlap with the protective resin 50. The overlapping portion 48A may overlap at least with the elastic wiring 20. On the other hand, the non-overlapping portion 48B does not overlap with the elastic wiring 20.

[0073] As shown in FIG. 6 , in the non-overlapping portion 48B, the opening edge 48 may be disposed opposite the edge 56 of the protective resin 50 along the in-plane direction of the main surface 12 of the stretchable substrate 10. The stretchable covering layer 40 may have an end surface 44 disposed opposite the edge 56 of the protective resin 50 at the opening edge 48. With this structure, the non-overlapping portion 48B of the stretchable covering layer 40 can contribute to retaining the protective resin 50 on the inner side of the opening 47 (i.e., the electronic component 30 side). Generally, the protective resin 50 can be formed by potting a resin material on the stretchable device. The protective resin 50 can be made of a resin material with poor stretchability to protect the electronic component 30. If the potted protective resin 50 is positioned over a wide area of ​​the stretchable device, the area with low stretchability will expand, potentially reducing the stretchability of the stretchable device as a whole.

[0074] According to the above-described structure, the non-overlapping portion 48B blocks the protective resin 50 that flows toward the outside of the opening 47, thereby suppressing the spread of the protective resin 50. That is, the non-overlapping portion 48B can keep the protective resin 50 in an area suitable for protecting the electronic component 30. In this way, the stretchable covering layer 40 can improve adhesion with the protective resin 50 at the overlapping portion 48A while suppressing the spread of the protective resin 50 at the non-overlapping portion 48B. This can improve the mounting reliability of the electronic component 30 while suppressing a decrease in the stretchability of the stretchable device.

[0075] [Second embodiment] Next, a stretchable device according to a second embodiment will be described. Fig. 7 is a plan view schematically showing a stretchable device 1D according to a second embodiment of the present disclosure. Fig. 8 is an enlarged cross-sectional view schematically showing an A-A cross section taken along the extension direction Z of the stretchable wiring 20 in the stretchable device 1D shown in Fig. 7. Fig. 9 is an enlarged cross-sectional view schematically showing a B-B cross section taken along a direction X different from the extension direction Z of the stretchable wiring 20 in the stretchable device 1D shown in Fig. 7.

[0076] As shown in the figure, the stretchable device 1D includes a further stretchable covering layer 80 located on the stretchable covering layer 40. Hereinafter, the stretchable covering layer 40 that covers at least the stretchable wiring 20 will be referred to as the first stretchable covering layer 40, and the further stretchable covering layer 40 located on the stretchable covering layer 40 will be referred to as the second stretchable covering layer 80. The stretchable wiring 20, the first stretchable covering layer 40, and the second stretchable covering layer 80 may be layered in this order.

[0077] As shown in Fig. 7 , when viewed in the thickness direction Y, the second stretchable covering layer 80 has an opening 87 defined by an opening edge 88 extending along the outer periphery of the protective resin 50. The protective resin 50 may be positioned inside the opening 87 of the second stretchable covering layer 80. In other words, the opening 87 of the second stretchable covering layer 80 may be open in the area where the protective resin 50 is disposed. As shown in Figs. 7 to 9 , when viewed in the thickness direction Y, the protective resin 50 does not need to overlap the second stretchable covering layer 80.

[0078] By providing the second stretchable covering layer 80, the protective resin 50 that pots the electronic component 30 can be suitably kept inside the opening 87 of the second stretchable covering layer 80, as shown in Fig. 7. In other words, the presence of the second stretchable covering layer 80 that has the opening 87 makes it possible to keep the placement area of ​​the protective resin 50 inside the opening 87. This can prevent the protective resin 50 from reducing the stretchability of the stretchable device.

[0079] As shown in Figure 8, in a cross-sectional view, the first stretchable covering layer 40 overlaps with the protective resin 50 at least in the region overlapping with the stretchable wiring 20. On the other hand, the second stretchable covering layer 80 does not need to overlap with the protective resin 50. With this structure, the overlap between the first stretchable covering layer 40 and the protective resin 50 improves the adhesion of the protective resin 50, thereby increasing the mounting reliability of the electronic component 30. Furthermore, by providing the second stretchable covering layer 80, it is possible to suppress a decrease in the stretchability of the stretchable device caused by excessive expansion of the arrangement region of the protective resin 50. This makes it possible to obtain a stretchable device that is favorable in terms of stretchability and mounting reliability of the electronic component 30.

[0080] 8 and 9 , the opening edge 88 of the second stretchable covering layer 80 may be disposed opposite the edge 56 of the protective resin 50 in the extension direction of the stretchable substrate 10. The second stretchable covering layer 80 may have an end surface 84 facing the inside of the opening 87. In a cross-sectional view, the end surface 84 may be disposed opposite the edge 56 of the protective resin 50 in the extension direction of the stretchable substrate 10. In such a structure, the end surface 84 can function as a barrier that suppresses the spread of the protective resin 50. This keeps the protective resin 50 inside the opening 87 of the second stretchable covering layer 80, making it possible to suppress a decrease in the stretchability of the stretchable device.

[0081] The edge 56 of the protective resin 50 and the opening edge 88 of the second stretchable covering layer 80 may be spaced apart from each other. Alternatively, the edge 56 of the protective resin 50 and the opening edge 88 of the second stretchable covering layer 80 may be in contact with each other. For example, the edge 56 of the protective resin may be in contact with the end surface 84 of the second stretchable covering layer 80. In such a structure, the protective resin 50 may be in contact with both the first stretchable covering layer 40 and the second stretchable covering layer 80. This increases the contact area of ​​the protective resin 50 with the stretchable device, and the adhesive strength of the protective resin 50 may be improved.

[0082] When prioritizing the suppression of the spread of the protective resin 50 by the second stretchable covering layer 80 in a cross-sectional view, the thickness T2 (see FIG. 9 ) of the second stretchable covering layer 80 is preferably 1 μm or more, and more preferably 10 μm or more. Furthermore, when prioritizing the stretchability of the entire stretchable device, the thickness of the second stretchable covering layer 80 is preferably 100 μm or less.

[0083] The thickness T2 of the second stretchable covering layer 80 does not need to be constant. For example, the thickness T2 of the second stretchable covering layer 80 in the region overlapping with the stretchable wiring 20 and the first stretchable covering layer 40 may be smaller than the thickness T2 of the second stretchable covering layer 80 in the region not overlapping with the stretchable wiring 20 or the first stretchable covering layer 40. For example, by increasing the thickness of the second stretchable covering layer 80 in the region not overlapping with the stretchable wiring 20 or the first stretchable covering layer 40, the thickness of the entire stretchable device around the protective resin 50 may be made approximately uniform. By making the thickness uniform, the stretchability of the stretchable device can be made more uniform. This reduces stress concentration due to differences in stretchability and makes it possible to suppress the occurrence of breakage of the stretchable device.

[0084] The second stretchable covering layer 80 may extend over the entire stretchable device. The second stretchable covering layer 80 may extend over the entire stretchable device except for the opening 87 where the protective resin 50 is located. This can improve the mechanical strength of the entire stretchable device. Furthermore, the difference in stretchability between the area where the second stretchable covering layer 80 is disposed and the area where it is not disposed can be reduced, making the stretchability of the entire stretchable device more uniform. Therefore, if emphasis is placed on the strength of the stretchable device, it may be preferable to dispose the second stretchable covering layer 80 over the entire stretchable device. On the other hand, if emphasis is placed on improving the stretchability of the stretchable device, the second stretchable covering layer 80 may be disposed only around the protective resin 50, as described below.

[0085] (Modifications of Second Embodiment) The stretchable device according to the second embodiment can adopt various modifications. Fig. 10 is a plan view schematically showing a stretchable device 1E according to a modification of the second embodiment of the present disclosure. Figs. 11 and 12 are schematic cross-sectional views of the stretchable device 1E shown in Fig. 10.

[0086] As shown in FIG. 10 , the second stretchable covering layer 80 may have a frame-like shape extending along the outer periphery of the protective resin 50 when viewed from the thickness direction Y. That is, the second stretchable covering layer 80 may have a frame-like shape that surrounds the periphery of the protective resin 50. This structure can also be interpreted as a frame-like structure having an opening 87 when viewed from the thickness direction Y, where the strip-shaped second stretchable covering layer 80 is arranged to surround the periphery of the protective resin 50. The stretchable wiring 20 may be covered by both the first stretchable covering layer 40 and the second stretchable covering layer 80 around the periphery of the protective resin 50. On the other hand, in areas other than the periphery of the protective resin 50, the stretchable wiring 20 may be covered by the first stretchable covering layer 40, but may not be covered by the second stretchable covering layer 80.

[0087] In such a structure, the second stretchable covering layer 80 is disposed only around the protective resin 50. The thickness of the stretchable device can be reduced because the second stretchable covering layer 80 is not disposed in areas other than the periphery of the protective resin 50. This can realize a reduction in the height of the stretchable device and an improvement in the stretchability of the stretchable device as a whole.

[0088] Fig. 13 is a plan view schematically showing a stretchable device 1F according to another modified mode of the second embodiment of the present disclosure. Fig. 14 is a cross-sectional view schematically showing the B-B cross section of the stretchable device 1F shown in Fig. 13.

[0089] 13 , in the stretchable device 1F, the first stretchable covering layer 40 may have an opening 47 that opens at the location where the electronic component 30 is placed. That is, both the first stretchable covering layer 40 and the second stretchable covering layer 80 may have an opening. For ease of explanation, hereinafter, the opening 47 of the first stretchable covering layer 40 will be referred to as the first opening 47, and the opening 87 of the second stretchable covering layer 80 will be referred to as the second opening 87. Similarly, the opening edge 48 of the first opening 47 will be referred to as the first opening edge, and the opening edge 88 of the second opening 87 will be referred to as the second opening edge.

[0090] When viewed from the thickness direction Y, the first opening 47 and the second opening 87 may have a partial overlap. When viewed from the thickness direction Y, the first opening edge 48 that defines the first opening 47 may have an overlap with the protective resin 50 at least in the region that overlaps with the elastic wiring 20. On the other hand, the second opening edge 88 of the second opening 87 does not have to have an overlap with the protective resin 50.

[0091] 14 , in a region that does not overlap with the stretchable wiring 20 when viewed from the thickness direction Y, the first opening edge 48 of the first stretchable covering layer 40 and the second opening edge 88 of the second stretchable covering layer 80 may be at least partially flush with each other. For example, in a region that does not overlap with the stretchable wiring 20 when viewed from the thickness direction Y, the end face 44 that defines the first opening 47 of the first stretchable covering layer 40 and the end face 84 that defines the second opening 87 of the second stretchable covering layer 80 may be at least partially flush with each other in a cross-sectional view. With this structure, the first stretchable covering layer 40 and the second stretchable covering layer 80 can both suppress the spread of the protective resin 50.

[0092] [Third embodiment] Next, a description will be given of a stretchable device 1G according to a third embodiment. Fig. 15 is an enlarged cross-sectional view schematically showing a cross section taken along the extension direction Z of the stretchable wiring 20 in a stretchable device 1G according to a third embodiment of the present disclosure.

[0093] The stretchable device 1G according to the third embodiment further includes a mounting electrode section 70 interposed between the stretchable wiring 20 and the connection section 60. The mounting electrode section 70 may be disposed on the main surface 22 of the stretchable wiring 20. The connection section 60 and the stretchable wiring 20 are electrically connected via the mounting electrode section 70. In other words, the electronic component 30 and the stretchable wiring 20 are indirectly electrically connected via the connection section 60 and the mounting electrode section 70.

[0094] Solder may be used as the connection part 60 that electrically connects the electronic component 30 and the stretchable wiring 20. On the other hand, when the stretchable wiring 20 containing a stretchable resin is directly joined to the solder, the so-called solder erosion phenomenon may cause the properties of the material of the stretchable wiring 20 to change. This reduces the mechanical strength of the stretchable wiring 20, making the stretchable wiring 20 more susceptible to breakage near the connection part 60, and may reduce the mounting reliability of the electronic component 30.

[0095] In the stretchable device 1G of the present disclosure, the mounting electrode section 70 is interposed between the stretchable wiring 20 and the connection section 60, thereby making it possible to electrically connect the electronic component 30 and the stretchable wiring 20 while avoiding contact between the stretchable wiring 20 and the connection section 60. By selecting a material that has excellent solder leach resistance and solder wettability as the mounting electrode section 70, it is possible to improve the connection strength between the connection section 60 and the stretchable wiring 20.

[0096] Furthermore, by arranging the protective resin 50 so that it extends to the stretchable covering layer 40, the protective resin 50 can cover the mounting electrode section 70. This allows the mounting electrode section 70, which is responsible for the electrical connection between the electronic component 30 and the stretchable wiring 20, to be suitably protected by the protective resin 50. Furthermore, the protective resin 50 may be in contact not only with the stretchable covering layer 40 but also with the mounting electrode section 70. This structure allows the protective resin 50 to adhere firmly to the stretchable device 1G, and can prevent the electronic component 30 from falling off from the stretchable device 1G.

[0097] The mounting electrode portion 70 may be a mixture of conductive particles and a resin. The conductive particles may be, for example, at least one metal powder selected from the group consisting of Ag (silver), Cu (copper), and Ni (nickel). The average particle size of the conductive particles is not particularly limited, but is preferably 0.01 μm or more and 10 μm or less. The shape of the conductive particles is also not particularly limited, but may be, for example, approximately spherical, approximately ellipsoidal, polyhedral, flat, or irregular, such as a shape with protrusions. The resin mixed with the conductive particles may be a known resin with excellent solder leach resistance and solder wettability. For example, the resin constituting the mounting electrode portion 70 may be at least one resin selected from the group consisting of ester-based resins, epoxy-based resins, urethane-based resins, acrylic-based resins, phenol-based resins, and silicone-based resins.

[0098] The thickness of the mounting electrode portion 70 is preferably 100 μm or less, and more preferably 50 μm or less. In addition, when the mechanical strength of the mounting electrode portion 70 is important, the thickness of the mounting electrode portion 70 is preferably 1 μm or more.

[0099] When viewed from the thickness direction Y, the connection section 60, the mounting electrode section 70, and the stretchable wiring 20 may partially overlap each other. In other words, the connection section 60, the mounting electrode section 70, and the stretchable wiring 20 may have a structure in which they are stacked in the thickness direction Y. The mounting electrode section 70 may have two main surfaces extending along the extension direction of the stretchable device 1B, and may be joined to the stretchable wiring 20 at one main surface and joined to the connection section 60 at the other main surface.

[0100] (Modification of Third Embodiment) FIGS. 16 and 17 are cross-sectional views schematically showing stretchable devices 1H and 1J, respectively, which are modifications of the second embodiment. As shown in the figures, the mounting electrode section 70 and the stretchable wiring 20 may be connected at their ends. That is, when viewed from the thickness direction Y, the end 75 of the mounting electrode section 70 and the end 25 of the stretchable wiring 20 may overlap each other. Specifically, the mounting electrode section 70 may overlap the end 25 of the stretchable wiring 20 at the end 75 located distal to the electronic component 30. In such a structure, the mounting electrode section 70 may be joined to the main surface 12 of the stretchable substrate 10. In the cross-sectional view shown in FIG. 16 , the stretchable wiring 20 may be located distal to the electronic component relative to the connection section 60.

[0101] In such a structure, the connection section 60 and the stretchable wiring 20 may be arranged offset from each other without overlapping each other when viewed from the thickness direction Y. This makes it possible to reduce the thickness of the entire stretchable device around the electronic component 30. Furthermore, by reducing the overlapping area between the stretchable wiring 20 and the mounting electrode section 70, bleeding of the wiring 20 and the mounting electrode section 70 during printing can be suppressed.

[0102] 16 and 17 , the mounting electrode section 70 includes a first connection region 74 that joins with the stretchable wiring 20, and a second connection region 76 that joins with the connecting section 60. The first connection region 74 and the second connection region 76 may not overlap with each other when viewed from the thickness direction Y. The first connection region 74 and the second connection region 76 may be adjacent to each other and spaced apart from each other along the extension direction Z of the stretchable wiring 20. The first connection region 74 may be positioned more distal from the electronic component 30 than the second connection region 76. In other words, the second connection region 76 may be positioned more proximal to the electronic component 30 than the first connection region 74.

[0103] 16 , the end 25 of the stretchable wiring 20 may ride up onto the main surface 72 of the mounting electrode section 70. In a cross-sectional view, the end 75 of the mounting electrode section 70 may be located between the stretchable substrate 10 and the stretchable wiring 20. According to this structure, the end 75 of the mounting electrode section 70 is pressed down by the stretchable wiring 20, and therefore peeling of the mounting electrode section 70 due to expansion and contraction of the stretchable device can be suppressed.

[0104] 17 , an end 75 of the mounting electrode section 70 may ride up onto the main surface 22 of the stretchable wiring 20. In a cross-sectional view, an end 25 of the stretchable wiring 20 may be located between the stretchable substrate 10 and the mounting electrode section 70. According to such a structure, the mounting electrode section 70 is located on the end 25 of the stretchable wiring 20, so that contact between the connecting section 60 and the stretchable wiring 20 can be suitably avoided. When solder is used as the material of the connecting section 60, such a structure can be particularly useful in preventing solder erosion due to contact between the stretchable wiring 20 and the solder.

[0105] The stretchable covering layer 40 may cover the stretchable wiring 20 extending from the connection portion with the mounting electrode section 70 in a direction away from the electronic component 30. The stretchable covering layer 40 may cover the first connection region 74. Alternatively, when viewed from the thickness direction Y, the stretchable covering layer 40 may not overlap the first connection region 74 between the mounting electrode section 70 and the stretchable wiring 20. The first connection region 74 and the stretchable covering layer 40 may be adjacent to and spaced apart from each other along the extension direction Z of the stretchable wiring 20. In such a structure, the stretchable covering layer 40 may be disposed farther away from the electronic component 30 than the first connection region 74. The protective resin 50 may integrally cover the electronic component 30, the first connection region 74, the second connection region 76, and the periphery 45 of the stretchable covering layer 40.

[0106] When viewed from the thickness direction Y, the protective resin 50 may extend from the position where it overlaps with the electronic component 30 at the center toward the periphery of the electronic component 30 to the periphery 45 of the stretchable covering layer 40. The thickness of the protective resin 50 may gradually decrease from the electronic component 30 side toward the periphery 45 side of the protective resin 50.

[0107] 16 and 17 , the stretchable wiring 20 is disposed on the main surface 12 of the stretchable substrate 10, spaced apart from the electronic component 30. Furthermore, the stretchable covering layer 40 may cover the stretchable wiring 20 extending in a direction away from the electronic component 30, excluding the end portion 25 of the stretchable wiring 20. Therefore, the total thickness of the stretchable substrate 10, stretchable wiring 20, and stretchable covering layer 40, which are stretchable members, increases stepwise with increasing distance from the electronic component 30. According to this structure, the thickness of the protective resin 50 decreases with increasing distance from the electronic component 30, while the total thickness of the stretchable substrate 10, stretchable wiring 20, and stretchable covering layer 40 increases stepwise with increasing distance from the electronic component 30. This allows the thickness of the entire stretchable device to be uniform around the electronic component 30. Furthermore, by gradually changing the thickness of the protective resin 50, which has poor elasticity, and the elastic substrate 10, elastic wiring 20, and elastic coating layer 40, which have elasticity, the change in elasticity of the entire stretchable device can be made more gradual.

[0108] (Method for Producing a Stretchable Device) An exemplary method for producing a stretchable device according to an embodiment of the present disclosure will now be described.

[0109] First, a stretchable substrate is prepared, and then a stretchable wiring is formed on the main surface of the stretchable substrate.

[0110] The stretchable wiring may be formed by printing a conductive paste (for example, a conductive paste containing a mixture of conductive particles and a resin) onto a stretchable substrate using screen printing, inkjet printing, etc. This allows the desired circuit pattern to be obtained.

[0111] After forming the circuit pattern of the stretchable wiring, the printed conductive paste may be dried and cured to form the stretchable wiring on the stretchable substrate.

[0112] After the formation of the stretchable wiring, a stretchable covering layer is formed to cover the stretchable wiring. The stretchable covering layer may be formed so as to cover the stretchable wiring except for the portion where the electronic component, described below, is placed. In other words, the stretchable covering layer may partially cover the stretchable wiring so that at least the connection portion with the electronic component is exposed. The stretchable covering layer may be formed by applying or printing a paste or ink-like material. Alternatively, the stretchable covering layer may be formed by thermocompression bonding a film or sheet-like material onto the stretchable wiring. When the stretchable device includes a second stretchable covering layer as an additional stretchable covering layer, the two stretchable covering layers may be thermocompression bonded separately, or the two stretchable covering layers may be laminated and then thermocompression bonded together.

[0113] If necessary, a mounting electrode part electrically connected to the elastic wiring may be formed. The mounting electrode part may be printed by screen printing, inkjet printing, or the like so as to overlap at least a part of the mounting electrode part with the elastic wiring, and then dried and cured to form the mounting electrode part.

[0114] Next, electronic components are mounted. Mounting of electronic components may be performed using a connecting material such as solder or a conductive adhesive. For example, the connecting material may be applied to desired positions on the circuit pattern of the stretchable wiring, and then the electronic components may be mounted. When solder is used as the connecting material, the solder may be melted and solidified by heat treatment in a reflow furnace or the like with the electronic components mounted. This forms a connection that electrically connects the electronic components and the stretchable wiring, and the electronic components are mounted on the stretchable device.

[0115] After mounting the electronic components, a protective resin is formed. The protective resin may be formed by adding (potting) or applying a resin material so that it covers the electronic components and partially overlaps with the stretchable coating layer. In this case, the area where the protective resin is added may be adjusted so that the overlap width between the stretchable coating layer located on the stretchable wiring and the protective resin is larger than the thickness of the stretchable coating layer. In this way, a stretchable device of the present disclosure having excellent mounting reliability for electronic components can be obtained.

[0116] Although the embodiments of the present disclosure have been described above, they are merely typical examples. Those skilled in the art will readily understand that the present disclosure is not limited thereto, and that various modifications are possible within the scope of the present disclosure.

[0117] For example, a plurality of stretchable wires 20 may be connected to the electronic component 30. Fig. 18 is a plan view schematically showing a stretchable device 1E according to an embodiment of the present disclosure. As shown in the figure, the plurality of stretchable wires 20 may extend in the same direction as each other, or in directions different from each other. The above-mentioned features related to the overlapping region 52 and the features related to the connection portion between the electronic component 30 and the stretchable wires 20 may be applied to each of the plurality of stretchable wires 20 connected to the electronic component 30. For example, when viewed from the thickness direction Y, the overlapping region 52 may be arranged in a position overlapping with each of the plurality of stretchable wires 20. Each of the plurality of stretchable wires 20 may have the same structure, or may have a different structure.

[0118] It should be noted that one embodiment of the present disclosure as described above includes the following preferred aspects. <1> A stretchable device comprising a stretchable substrate, stretchable wiring disposed on a main surface of the stretchable substrate, an electronic component electrically connected to the stretchable wiring, a first stretchable covering layer covering the stretchable wiring, and a protective resin covering the electronic component, wherein the stretchable substrate has an overlapping region in which the protective resin and a portion of the first stretchable covering layer overlap when viewed in a thickness direction of the stretchable substrate, the overlapping region being positioned so as to overlap at least the stretchable wiring when viewed in the thickness direction, and an overlapping width between the first stretchable covering layer and the protective resin in the overlapping region being greater than a thickness of the first stretchable covering layer. <2> The stretchable device according to <1>, wherein the protective resin and the first stretchable covering layer are in contact with each other in the overlapping region. <3> The stretchable device according to <1> or <2>, wherein the overlapping region is a region in which a periphery of the protective resin and a periphery of the first stretchable covering layer overlap each other when viewed in the thickness direction. <4> The stretchable device according to any one of <1> to <3>, further comprising a connecting part that electrically connects the electronic component and the stretchable wiring, and wherein a separation region exists in which the connecting part and the first stretchable covering layer are separated from each other when viewed in the thickness direction. <5> The stretchable device according to <4>, wherein the protective resin is in contact with the stretchable wiring at the separation region. <6> The stretchable device according to any one of <1> to <5>, wherein the first stretchable covering layer comprises a main surface of the first stretchable covering layer positioned opposite the stretchable wiring and an end surface facing the electronic component, and the protective resin is in contact with the main surface and the end surface of the first stretchable covering layer. <7> The stretchable device according to any one of <1> to <6>, wherein the first stretchable covering layer comprises a first opening that penetrates along the thickness direction, the electronic component is positioned in the first opening, and at least a part of a first opening edge that defines the first opening overlaps with the protective resin when viewed in the thickness direction. <8> The stretchable device according to <7>, wherein a first opening edge of the first opening includes a non-overlapping portion that does not overlap with the stretchable wiring and the protective resin when viewed in the thickness direction.<9> The stretchable device according to <7> or <8>, wherein the overlapping region is positioned along a periphery of the first opening. <10> The stretchable device according to any one of <1> to <9>, further comprising: a connection portion connected to the electronic component; and a mounting electrode portion connected to each of the connection portion and the stretchable wiring, and electrically connecting the electronic component and the stretchable wiring via the connection portion. <11> The stretchable device according to <10>, wherein, as viewed in the thickness direction, the mounting electrode portion is connected to the connection portion at one end portion proximal to the electronic component, and is disposed so as to overlap with an end portion of the stretchable wiring at the other end portion distal to the electronic component. <12> The stretchable device according to <11>, wherein the mounting electrode portion comprises a first connection region connected to the stretchable wiring and a second connection region connected to the connection portion, and the first connection region is positioned farther from the electronic component than the second connection region is in an extension direction of the stretchable substrate. <13> The stretchable device according to <12>, wherein the protective resin integrally covers the electronic component, the first connection region, the second connection region, and a portion of the first stretchable covering layer. <14> The stretchable device according to <12> or <13>, wherein, as viewed in the thickness direction, the first stretchable covering layer is positioned farther away from the electronic component than the first connection region is. <15> The stretchable device according to any one of <1> to <14>, wherein the electronic component and the stretchable wiring are electrically connected via a conductive adhesive. <16> The stretchable device according to any one of <1> to <15>, further comprising a second stretchable covering layer covering at least a portion of the first stretchable covering layer, wherein, as viewed in the thickness direction, the second stretchable covering layer has a second opening defined by a second opening edge extending along an outer circumferential edge of the protective resin. <17> The stretchable device according to <16>, wherein the protective resin overlaps a part of the first stretchable covering layer on the stretchable wiring but does not overlap the second stretchable covering layer when viewed from the thickness direction. <18> The stretchable device according to <16> or <17>, wherein the second opening edge of the second stretchable covering layer is disposed opposite an edge of the protective resin in the extension direction of the stretchable base material.<19> The stretchable device according to any one of <16> to <18>, wherein the second stretchable covering layer has a frame-like shape extending along an outer peripheral edge of the protective resin when viewed in the thickness direction. <20> The stretchable device according to any one of <16> to <19>, wherein the first stretchable covering layer has a first opening that opens at the second opening of the second stretchable covering layer, and a first opening edge that defines the first opening of the first stretchable covering layer and the second opening edge of the second stretchable covering layer are at least partially flush in a cross-sectional view in a region that does not overlap with the stretchable wiring when viewed in the thickness direction.

[0119] The above effects are merely exemplary, and the present disclosure is not limited to the above, and additional effects may also be provided.

[0120] 1A, 1B: Stretchable device 10: Stretchable substrate 12: Main surface of stretchable substrate 20: Stretchable wiring 22: Main surface of stretchable wiring 25: End of stretchable wiring 30: Electronic component 40: Stretchable covering layer 42: Main surface of stretchable covering layer 44: End face of stretchable covering layer 45: Periphery of stretchable covering layer 46: Edge of stretchable covering layer 47: Opening 48: Opening edge 50: Protective resin 52: Overlapping region 52a: First overlapping region 52b: Second overlapping region 53: Separation region 54: Non-covered region 55: Periphery of protective resin 56: Edge of protective resin 60: Connection portion 70: Mounting electrode portion 72, 73: Main surface of mounting electrode portion 74: First connection region 76: Second connection region 75: End of mounting electrode portion 80: Second stretchable covering layer 44: End surface of stretchable covering layer 87: Opening 88: Opening edge

Claims

1. A stretchable device comprising a stretchable substrate, stretchable wiring arranged on a main surface of the stretchable substrate, electronic components electrically connected to the stretchable wiring, a first stretchable covering layer covering the stretchable wiring, and a protective resin covering the electronic components, wherein the stretchable substrate has an overlapping region in which the protective resin and a portion of the first stretchable covering layer overlap when viewed in the thickness direction, the overlapping region is positioned so as to overlap at least the stretchable wiring when viewed in the thickness direction, and the overlap width between the first stretchable covering layer and the protective resin in the overlapping region is greater than the thickness of the first stretchable covering layer.

2. The stretchable device according to claim 1, wherein the protective resin and the first stretchable covering layer are in contact with each other in the overlapping region.

3. The stretchable device according to claim 1 or 2, wherein, when viewed in the thickness direction, the overlapping region is a region where the periphery of the protective resin and the periphery of the first stretchable covering layer overlap each other.

4. The stretchable device according to any one of claims 1 to 3, further comprising a connection part that electrically connects the electronic component and the stretchable wiring, wherein, when viewed in the thickness direction, there is a separation region that separates the connection part from the first stretchable covering layer.

5. The stretchable device according to claim 4, wherein the protective resin is in contact with the stretchable wiring in the separated region.

6. The stretchable device according to any one of claims 1 to 5, wherein the first stretchable covering layer has a main surface of the first stretchable covering layer located opposite the stretchable wiring and an end surface facing the electronic component, and the protective resin is in contact with the main surface and the end surface of the first stretchable covering layer.

7. The stretchable device according to any one of claims 1 to 6, wherein the first stretchable covering layer has a first opening penetrating along the thickness direction, the electronic component is positioned in the first opening, and at least a portion of a first opening edge defining the first opening overlaps with the protective resin when viewed from the thickness direction.

8. The stretchable device according to claim 7, wherein a first opening edge of the first opening includes a non-overlapping portion that does not overlap with the stretchable wiring and the protective resin when viewed in the thickness direction.

9. The stretchable device of claim 7 or 8, wherein the overlap region is positioned along a periphery of the first opening.

10. The stretchable device according to any one of claims 1 to 9, further comprising: a connection part connected to the electronic component; and a mounting electrode part connected to each of the connection part and the stretchable wiring, and electrically connecting the electronic component and the stretchable wiring via the connection part.

11. The stretchable device according to claim 10, wherein, when viewed in the thickness direction, the mounting electrode portion is connected to the connection portion at one end on a proximal side of the electronic component, and is arranged so as to overlap an end of the stretchable wiring at the other end on a distal side from the electronic component.

12. The stretchable device according to claim 11, wherein the mounting electrode portion comprises a first connection region connected to the stretchable wiring and a second connection region connected to the connection portion, and the first connection region is positioned farther away from the electronic component than the second connection region is in the extension direction of the stretchable substrate.

13. The stretchable device according to claim 12, wherein the protective resin integrally covers the electronic component, the first connection region, the second connection region, and a portion of the first stretchable covering layer.

14. The stretchable device according to claim 12 or 13, wherein the first stretchable covering layer is positioned farther away from the electronic component than the first connection region is when viewed in the thickness direction.

15. The stretchable device according to any one of claims 1 to 14, wherein the electronic component and the stretchable wiring are electrically connected via a conductive adhesive.

16. The stretchable device according to any one of claims 1 to 15, further comprising a second stretchable covering layer covering at least a portion of the first stretchable covering layer, wherein, as viewed in the thickness direction, the second stretchable covering layer comprises a second opening defined by a second opening edge extending along the outer periphery of the protective resin.

17. The stretchable device according to claim 16, wherein, when viewed in the thickness direction, the protective resin overlaps a portion of the first stretchable covering layer on the stretchable wiring, but does not overlap the second stretchable covering layer.

18. The stretchable device according to claim 16 or 17, wherein the second opening edge of the second stretchable covering layer is disposed opposite the edge of the protective resin in the extension direction of the stretchable substrate.

19. The stretchable device according to any one of claims 16 to 18, wherein the second stretchable covering layer has a frame-like shape extending along the outer periphery of the protective resin when viewed in the thickness direction.

20. The stretchable device according to any one of claims 16 to 19, wherein the first stretchable covering layer has a first opening that opens at the second opening of the second stretchable covering layer, and in an area that does not overlap with the stretchable wiring as viewed in the thickness direction, a first opening edge that defines the first opening of the first stretchable covering layer and the second opening edge of the second stretchable covering layer are at least partially flush in a cross-sectional view.

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