Stretchable device

Abstract

In one embodiment of the present invention, there is provided a stretchable device including a stretchable base material and a stretchable wiring disposed on the stretchable base material, the elastic loss modulus E "(S) of the stretchable base material being smaller than the elastic loss modulus E" (W) of the stretchable wiring.

Description

Technical Field

[0001] The present invention relates to a stretchable device. Background Art

[0002] Conventionally, a stretchable device including a stretchable substrate and stretchable wiring disposed on the stretchable substrate has been known.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-181958 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] Here, in the stretchable device, the inventors of the present application have found that there are matters to be improved in the following aspects.

[0008] Specifically, in the stretchable device, the proportion of the stretchable substrate relative to the stretchable wiring is relatively large, and for this reason, as the entire device, the contribution to the stretching operation may be large. Therefore, if the stretchable substrate is prone to plastic deformation (i.e., prone to relaxation) during stretching, then for this reason, the stretchable wiring disposed on the stretchable substrate gradually elongates, and there is a risk that the wiring resistance of the stretchable wiring becomes high.

[0009] Based on the above, it is desirable that the stretchable substrate, which is a constituent element of the stretchable device, is not prone to plastic deformation during stretching.

[0010] Therefore, an object of the present invention is to provide a stretchable device including a stretchable substrate that is not prone to plastic deformation during stretching.

[0011] Solution to the Problem

[0012] To achieve the above object, in one aspect of the present invention, there is provided a stretchable device, wherein,

[0013] the stretchable device includes a stretchable substrate and stretchable wiring disposed on the stretchable substrate,

[0014] the loss elastic modulus E”(S) of the stretchable substrate is smaller than the loss elastic modulus E”(W) of the stretchable wiring.

[0015] Effects of the Invention

[0016] According to the stretchable device of one aspect of the present invention, it is possible to make the stretchable substrate not prone to plastic deformation during stretching. Brief Description of the Drawings

[0017] Figure 1 This is a cross-sectional view schematically showing the stretchable device according to the first embodiment of the present invention.

[0018] Figure 2 This is a cross-sectional view schematically showing the stretchable device according to the second embodiment of the present invention.

[0019] Figure 3 This is a cross-sectional view schematically showing the stretchable device according to the third embodiment of the present invention. Detailed Embodiments

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each embodiment, aspects different from those described previously will be mainly described. In particular, the same functions and effects achieved by the same structure will not be repeatedly mentioned in each embodiment. Regarding the components in the following embodiments that are not described in the independent claims, they will be described as optional components. In addition, the sizes and size ratios of the components shown in the drawings are not necessarily strict. Also, in each figure, the same reference numerals are assigned to substantially the same structures, and there may be cases where repeated descriptions are omitted or simplified.

[0021] [First Embodiment]

[0022] Hereinafter, with reference to Figure 1 , the structure of the stretchable device 100 according to the first embodiment of the present invention will be described. Figure 1 This is a cross-sectional view schematically showing the stretchable device according to the first embodiment of the present invention.

[0023] The stretchable device 100 according to the first embodiment of the present invention includes a stretchable substrate 10 and at least one stretchable wiring disposed on the stretchable substrate 10. As the at least one stretchable wiring, for example, the first stretchable wiring 20 and the second stretchable wiring 30 can be cited.

[0024] In addition, "above" in this specification includes a state above and separated from a certain element, that is, a state located on the upper side of a certain element with another object in between, a state located at a spaced interval above a certain element, and a state located directly above and in contact with a certain element.

[0025] Therefore, in this specification, "stretchable wiring disposed on a stretchable substrate" includes a stretchable wiring in a state of being in contact with the main surface of the stretchable substrate and a stretchable wiring in a state of being separated from the main surface of the stretchable substrate without directly contacting the main surface and separated by other members (for example, a resin layer described later).

[0026] As the resin layer, for example, it can be formed of at least one resin material selected from the group consisting of polyimide resins, epoxy resins, polyurethane resins, and acrylic resins. Additionally, as the resin layer, it can be formed of inorganic materials such as alumina and silica.

[0027] Furthermore, the stretchable substrate is a sheet-like or film-like stretchable substrate, for example, composed of a stretchable resin material. As the resin material of the stretchable substrate, for example, styrene elastomers, olefin elastomers, polyurethane elastomers, silicone elastomers, etc. can be cited.

[0028] The thickness of the stretchable substrate is not particularly limited, but from the viewpoint of not hindering the stretching of the biological surface when adhered to the organism, it is preferably 100 μm or less, more preferably 50 μm or less. Additionally, from the viewpoint of ensuring a predetermined strength, the thickness of the stretchable substrate is preferably 10 μm or more.

[0029] Each stretchable wiring includes conductive particles and a resin. As each stretchable wiring, for example, a mixture composed of metal powders such as Ag, Cu, Ni, etc. as the conductive particles and resin materials such as acrylic and silicone can be cited. The average particle size of the conductive particles is not particularly limited, but it is preferably 0.01 μm or more and 10 μm or less. Additionally, the shape of the conductive particles is preferably spherical.

[0030] The thickness of each stretchable wiring is not particularly limited, but it is preferably 100 μm or less, more preferably 50 μm or less. Additionally, the thickness of each stretchable wiring is preferably 0.01 μm or more. The line width of each stretchable wiring is not particularly limited, but it is preferably 0.1 μm or more, more preferably 1 mm or less. Additionally, the shape, etc. of each stretchable wiring are not particularly limited.

[0031] On the premise of the above structure, the inventors of the present application have conducted in-depth research on countermeasures for providing a stretchable substrate that is not easily plastically deformed when the stretchable device stretches. As a result, the inventors of the present application have not focused on the structure and shape of each component of the stretchable device, but rather on the viscoelastic properties, thus proposing the present invention.

[0032] Specifically, the present invention is characterized in that in the stretchable device 100, the loss elastic modulus E”(S) of the stretchable substrate 10 is smaller than the loss elastic modulus E”(W) of the stretchable wirings 20 and 30. The loss elastic modulus mentioned in this specification refers to a measure of the energy lost from the component due to heat generation, etc. during deformation, and refers to the degree of relaxation of the stretchable substrate / stretchable wiring. The larger this value, the easier the component is to relax, and the smaller this value, the less likely the component is to relax.

[0033] According to this feature, the loss elastic modulus E”(S) of the stretchable substrate 10 is smaller than the loss elastic modulus E”(W) of the stretchable wirings 20 and 30. Therefore, during stretching, the stretchable substrate is less likely to plastically deform compared to the stretchable wirings. That is, it is possible to make the stretchable substrate less likely to slacken compared to the stretchable wirings during stretching. As a result, it is possible to suppress the gradual elongation of the stretchable wirings 20 and 30 disposed on the stretchable substrate 10, and thus it is possible to suppress the increase in the wiring resistance of the stretchable wirings 20 and 30.

[0034] In the above content, from the viewpoint of making the stretchable substrate less likely to plastically deform than the stretchable wirings, the ratio of the loss elastic modulus E”(S) of the stretchable substrate 10 to the loss elastic modulus E”(W) of the stretchable wirings 20 and 30 is less than 1.

[0035] For example, the upper limit of the above ratio can be, for example, 0.6 or less. From the viewpoint of making the stretchable substrate less likely to plastically deform than the stretchable wirings, the upper limit of the above ratio is preferably 0.1 or less, can be, for example, 0.07, more preferably 0.05 or less, and even more preferably 0.02 or less.

[0036] In addition, in the present embodiment, it is preferable that the storage elastic modulus E’(S) of the stretchable substrate 10 is smaller than the storage elastic modulus E’(W) of the stretchable wirings 20 and 30.

[0037] The storage elastic modulus referred to in this specification is a measure of the energy stored by a component during deformation, and is a value indicating the hardness degree of the stretchable substrate / stretchable wiring. The larger this value, the relatively harder the component, and the smaller this value, the softer the component.

[0038] According to this feature, as the stretchable substrate 10, a material that is relatively softer than the stretchable wirings 20 and 30 can be selected. Therefore, when the stretchable device 100 stretches, it is possible to less likely impede the stretching of the stretchable wirings.

[0039] In the above content, from the viewpoint of ensuring the stretching function of the substrate 10 itself, the ratio of the storage elastic modulus E’(S) of the stretchable substrate 10 to the storage elastic modulus E’(W) of the stretchable wirings 20 and 30 is 0.001 or more, and from the viewpoint of being softer than the stretchable wirings, the ratio of the storage elastic modulus E’(S) of the stretchable substrate 10 to the storage elastic modulus E’(W) of the stretchable wirings 20 and 30 is less than 1.0.

[0040] From the viewpoint of making the stretchable substrate 10 appropriately softer, the upper limit of the above ratio is preferably 0.5 or less, for example, 0.2 or less. From the viewpoint of making the stretchable substrate even more appropriately softer, the upper limit of the above ratio is more preferably 0.1 or less, for example, 0.06, and even more preferably 0.05 or less.

[0041] Specifically, from the viewpoint of ensuring the viscoelasticity of the stretchable substrate / stretchable wiring, the ratio of the loss tangent tanδ(S) of the stretchable substrate 10 to the loss tangent tanδ(W) of the stretchable wirings 20 and 30 is 0.01 or more, and from the viewpoint of suppressing the wiring resistance increase rate after repeated stretching to a predetermined value or less, the ratio of the loss tangent tanδ(S) of the stretchable substrate 10 to the loss tangent tanδ(W) of the stretchable wirings 20 and 30 is 6.0 or less.

[0042] In this specification, the loss tangent tanδ refers to the ratio of the loss elastic modulus E” of the stretchable wiring or stretchable substrate to the storage elastic modulus E’ of the stretchable wiring or stretchable substrate, and indicates which property, the elastic property or the viscous property, is more strongly exhibited in the deformation of a certain viscoelastic body.

[0043] In particular, when the ratio of the loss elastic modulus E”(S) of the above stretchable substrate to the loss elastic modulus E”(W) of the stretchable wiring is 0.1 or less, from the viewpoint of appropriately suppressing the wiring resistance increase rate after repeated stretching, the ratio of the loss tangent tanδ(S) of the stretchable substrate 10 to the loss tangent tanδ(W) of the stretchable wirings 20 and 30 is preferably 1.5 or less, more preferably 1.0 or less, and even more preferably 0.5 or less.

[0044] Moreover, on the premise that the loss elastic modulus E”(S) of the stretchable substrate 10 is smaller than the loss elastic modulus E”(W) of the stretchable wirings 20 and 30 and the stretchable substrate 10 and the stretchable wirings 20 and 30 have predetermined values, the following characteristics can be provided. Specifically, preferably, the ratio of the thickness of the stretchable wirings 20 and 30 to the overall thickness of the stretchable device 100 is 50% or less.

[0045] According to this characteristic, it is possible to suppress an increase in the wiring resistance that may occur when the proportion of the stretchable wiring in the entire stretchable device 100 is relatively large. From the viewpoint of appropriately suppressing such an increase in the wiring resistance, the above ratio of the thickness of the stretchable wiring is more preferably 30% or less, and even more preferably 15% or less. In addition, in the stretchable device 100, from the viewpoint of ensuring the wiring function, the above ratio of the thickness of the stretchable wiring is preferably 5% or more.

[0046] Further, from the aspect of the cross-sectional area that may be related to the thickness of the stretchable wiring, it is preferable that the ratio of the cross-sectional area of the stretchable wirings 20 and 30 to the overall cross-sectional area of the stretchable device 100 is 50% or less.

[0047] According to this feature, it is possible to suppress an increase in the wiring resistance that may occur when the proportion of the stretchable wiring in the entire stretchable device 100 is relatively large. From the viewpoint of appropriately suppressing such an increase in the wiring resistance, the ratio of the cross-sectional area of the stretchable wiring described above is more preferably 30% or less, and even more preferably 15% or less. Further, in the stretchable device 100, from the viewpoint of ensuring the wiring function, the ratio of the cross-sectional area of the stretchable wiring described above is preferably 2% or more.

[0048] In addition, the above-described stretchable device 100 can be manufactured through the following steps. Specifically, first, a stretchable substrate 10 is prepared. As the stretchable substrate 10, a stretchable substrate having a loss elastic modulus E”(S) smaller than the loss elastic modulus E”(W) of the stretchable wiring formed later is selected.

[0049] Next, after preparing the stretchable substrate 10, a continuous or independent wiring material is screen-printed on the prepared stretchable substrate 10 and then dried. Thereby, the stretchable wirings 20 and 30 can be formed on the stretchable substrate 10. Based on the above, the above-described stretchable device 100 can be manufactured.

[0050] [Second Embodiment]

[0051] Hereinafter, the second embodiment will be described. Figure 2 FIG. is a cross-sectional view schematically showing a stretchable device according to the second embodiment of the present invention. The second embodiment is different from the first embodiment in that it further has a coating layer 40 covering the stretchable substrate 10 and the stretchable wirings 20 and 30.

[0052] Also in this case, from the viewpoint of making the coating layer 40 less plastically deformable than the stretchable wiring during stretching, it is preferable that the coating layer 40 has the same viscoelastic characteristics as the stretchable substrate 10. Specifically, in the stretchable device 100A, it is preferable that the loss elastic modulus E”(S) of the coating layer 40 is smaller than the loss elastic modulus E”(W) of the stretchable wirings 20 and 30. Further, in the second embodiment, the stretchable substrate 10 and the coating layer 40 may not have the same material composition.

[0053] Accordingly, when stretching and contracting, both the stretchable substrate 10 and the coating layer 40 are less likely to plastically deform at substantially the same level as the stretchable wiring. As a result, as the stretchable device 100A as a whole, even with the coating layer 40 present, an increase in the wiring resistance of the stretchable wirings 20 and 30 can be appropriately suppressed.

[0054] [Third Embodiment]

[0055] Hereinafter, the third embodiment will be described. The third embodiment is different in that it further has a coating layer 10B that covers the stretchable substrate 10 and the stretchable wirings 20 and 30, compared to the first embodiment.

[0056] The coating layer 10B may have the same function as the coating layer 40 of the above-described second embodiment. In addition, in the third embodiment, the stretchable substrate 10 and the coating layer 10B can have the same material composition. Accordingly, when stretching and contracting, both the stretchable substrate 10 and the coating layer 10B are less likely to plastically deform at the same level as the stretchable wiring. As a result, as the stretchable device 100B as a whole, even with the coating layer 10B present, an increase in the wiring resistance of the stretchable wirings 20 and 30 can be more appropriately suppressed.

[0057] Examples

[0058] Hereinafter, examples of the present invention will be described.

[0059] Example 1

[0060] First, a stretchable substrate 10 was prepared. As the stretchable substrate 10, a stretchable substrate having a loss elastic modulus E”(S) smaller than the loss elastic modulus E”(W) of the stretchable wiring to be formed later was selected. Specifically, a styrenic elastomer was prepared as the stretchable substrate 10.

[0061] As this stretchable substrate 10, a stretchable substrate having the (1) loss elastic modulus E”(S), (2) storage elastic modulus E’(S), and (3) loss tangent tanδ(S) (E”(S) / E’(S)) shown in Table 1 was selected.

[0062] (1) Loss elastic modulus E”(S): 15.9 MPa

[0063] (2) Storage elastic modulus E’(S): 19.4 MPa

[0064] (3) Loss tangent tanδ(S) (E”(S) / E’(S)): 0.90

[0065] As the wiring material, a mixed material of Ag particles and an acrylic resin in which Ag particles are mixed is used. As this wiring material, it is set to have a material composition that can become a stretchable wiring having the (1) loss elastic modulus E”(W), (2) storage elastic modulus E’(W), and (3) loss tangent tanδ(W) (E”(W) / E’(W)) shown in Table 1 after device fabrication.

[0066] (1) Loss elastic modulus E”(W): 28.7 MPa

[0067] (2) Storage elastic modulus E’(W): 162.3 MPa

[0068] (3) Loss tangent tanδ(W) (E”(W) / E’(W)): 0.18

[0069] The wiring material is screen-printed on the prepared stretchable substrate 10, and then dried using a drying device. Thus, a stretchable device 100 including the stretchable substrate 10 and the stretchable wirings 20, 30 formed on the stretchable substrate is fabricated (refer to Figure 1 ).

[0070] Regarding the (1) loss elastic modulus E”, (2) storage elastic modulus E’, and (3) loss tangent tanδ (E” / E’) of the above-mentioned stretchable substrate 10 and stretchable wirings 20, 30, they are measured using a dynamic viscoelasticity measuring device (RSA-G2 manufactured by TA Instruments). Specifically, by vibrating the stretchable substrate up and down and deforming it to apply strain, the above-mentioned (1) loss elastic modulus E” and (2) storage elastic modulus E’ are respectively measured based on the waveform of the shear stress as the response and their phase difference. In addition, (3) loss tangent tanδ (E” / E’) is calculated based on the above-mentioned measured values.

[0071] Based on the above, the ratio of the loss elastic modulus E”(S) of the stretchable substrate to the loss elastic modulus E”(W) of the stretchable wiring is 0.56. The ratio of the storage elastic modulus E’(S) of the stretchable substrate to the storage elastic modulus E’(W) of the stretchable wiring is 0.12. In addition, the ratio of the loss tangent tanδ(S) of the stretchable substrate to the loss tangent tanδ(W) of the stretchable wiring is 5.08.

[0072] In this Example 1, in the fabricated stretchable device 100, the thickness of the stretchable wiring is 30 μm, and the overall thickness of the stretchable device is 100 μm. In addition, in the fabricated stretchable device 100, the cross-sectional area of the thickness of the stretchable wiring is 30% of the overall cross-sectional area of the stretchable device.

[0073] Measurement of wiring resistance before and after use of the device, measurement of wiring resistance increase rate, and determination of whether it can expand and contract

[0074] Under the above structure, the wiring resistance of the stretchable wiring of the stretchable device 100 before use (initial stage) is measured by the four-terminal measurement method. In this embodiment, the wiring resistance at this time is determined as 100 (index) as a reference. In addition, the wiring resistance of the stretchable wiring after the wiring is stretched by 10% and expanded and contracted 70 times is measured. The wiring resistance (index) at this time is 150 with respect to the wiring resistance (index) of 100 before use (initial stage) of the stretchable device 100 as a reference. Based on the above, the wiring resistance increase rate is +50%. Moreover, in this Embodiment 1, the stretchable device 100 can be expanded and contracted.

[0075] In addition, not only in this Embodiment 1, but also in the following Embodiments 2 to 8, examples with a wiring resistance increase rate of +100% or less are treated as embodiments, and examples with a wiring resistance increase rate greater than +100% are treated as comparative examples.

[0076] Hereinafter, the description after Embodiment 2 will be centered on the parts different from Embodiment 1. For descriptions that are repeated in the description of Embodiment 1, such descriptions will be omitted or skipped.

[0077] Embodiment 2

[0078] As shown in Table 1, compared with Embodiment 1, in Embodiment 2, the ratio of the thickness of the obtained stretchable wiring to the overall thickness of the stretchable device and the ratio of the cross-sectional area of the stretchable wiring to the overall cross-sectional area of the stretchable device are respectively changed in this way, and are different in this regard. On the other hand, regarding the ratio of the loss elastic modulus, the ratio of the storage elastic modulus, and the ratio of the loss tangent of the stretchable wiring and the stretchable substrate respectively, they are the same as those in Embodiment 1.

[0079] Under the above structure, the wiring resistance (index) after expansion and contraction is 200 with respect to the wiring resistance (index) of 100 before use (initial stage) of the stretchable device 100 as a reference. Based on the above, the wiring resistance increase rate is +100%. In addition, similar to Embodiment 1, the stretchable device 100 can be expanded and contracted.

[0080] Embodiment 3

[0081] As shown in Table 1, compared with Embodiment 1, in Embodiment 3, the ratio of the thickness of the obtained stretchable wiring to the overall thickness of the stretchable device and the ratio of the cross-sectional area of the stretchable wiring to the overall cross-sectional area of the stretchable device are respectively The method has been changed and is different in this aspect. On the other hand, regarding the ratios of the loss elastic modulus, the storage elastic modulus, and the loss tangent of the stretchable wiring and the stretchable substrate respectively, they are the same as those in Example 1.

[0082] Under the above structure, the stretched wiring resistance (index) is 135 with respect to the wiring resistance (index) 100 before use (initial) of the stretchable device 100 as a reference. Based on the above, the wiring resistance increase rate is +35%. In addition, similar to Example 1, the stretchable device 100 can be stretched.

[0083] Example 4

[0084] Compared with Example 1, in Example 4, a stretchable substrate having the (1) loss elastic modulus E”(S), (2) storage elastic modulus E’(S), and (3) loss tangent tanδ(S) (E”(S) / E’(S)) shown in Table 1 is selected as the stretchable substrate 10.

[0085] (1) Loss elastic modulus E”(S): 1.9 MPa

[0086] (2) Storage elastic modulus E’(S): 10.2 MPa

[0087] (3) Loss tangent tanδ(S) (E”(S) / E’(S)): 0.19

[0088] On the other hand, regarding the ratio of the thickness of the obtained stretchable wiring to the overall thickness of the stretchable device, the ratio of the cross-sectional area of the stretchable wiring to the overall cross-sectional area of the stretchable device, and the (1) loss elastic modulus E”(W), (2) storage elastic modulus E’(W), and (3) loss tangent tanδ of the stretchable wiring, they are the same as those in Example 1.

[0089] Based on the above, the ratio of the loss elastic modulus E”(S) of the stretchable substrate to the loss elastic modulus E”(W) of the stretchable wiring is 0.07. The ratio of the storage elastic modulus E’(S) of the stretchable substrate to the storage elastic modulus E’(W) of the stretchable wiring is 0.06. In addition, the ratio of the loss tangent tanδ(S) of the stretchable substrate to the loss tangent tanδ(W) of the stretchable wiring is 1.06.

[0090] Under the above structure, the stretched wiring resistance (index) is 135 with respect to the wiring resistance (index) 100 before use (initial) of the stretchable device 100 as a reference. Based on the above, the wiring resistance increase rate is +35%. In addition, similar to Example 1, the stretchable device 100 can be stretched.

[0091] Hereinafter, the description of Examples 5 and later will be centered on the parts different from Example 4. Descriptions that are repeated in Example 4 will be omitted or skipped.

[0092] Example 5

[0093] As shown in Table 1, compared with Example 4, in Example 5, the ratio of the thickness of the obtained stretchable wiring to the overall thickness of the stretchable device and the ratio of the cross-sectional area of the stretchable wiring to the overall cross-sectional area of the stretchable device were changed respectively in the following way, and they are different in this respect. On the other hand, regarding the ratios of the loss elastic modulus, the storage elastic modulus, and the loss tangent of the stretchable wiring and the stretchable substrate respectively, they are the same as those in Example 4.

[0094] Under the above structure, the stretchable wiring resistance (index) is 160 with respect to the wiring resistance (index) 100 before the use (initial stage) of the stretchable device 100 as a reference. Based on the above, the wiring resistance increase rate is +60%. In addition, similar to Example 1, the stretchable device 100 can be stretched.

[0095] Example 6

[0096] As shown in Table 1, compared with Example 4, in Example 6, the ratio of the thickness of the obtained stretchable wiring to the overall thickness of the stretchable device and the ratio of the cross-sectional area of the stretchable wiring to the overall cross-sectional area of the stretchable device were changed respectively in the following way, and they are different in this respect. On the other hand, regarding the ratios of the loss elastic modulus, the storage elastic modulus, and the loss tangent of the stretchable wiring and the stretchable substrate respectively, they are the same as those in Example 4.

[0097] Under the above structure, the stretchable wiring resistance (index) is 120 with respect to the wiring resistance (index) 100 before the use (initial stage) of the stretchable device 100 as a reference. Based on the above, the wiring resistance increase rate is +20%. In addition, similar to Example 1, the stretchable device 100 can be stretched.

[0098] Hereinafter, the description of Examples 7 and later will be centered on the parts different from Example 1. Descriptions that are repeated in Example 1 will be omitted or skipped.

[0099] Example 7

[0100] In Example 7, compared with Example 1, as the stretchable substrate 10, a stretchable substrate having the (1) loss elastic modulus E”(S), (2) storage elastic modulus E’(S), and (3) loss tangent tanδ(S) (E”(S) / E’(S)) shown in Table 1 was selected.

[0101] (1) Loss elastic modulus E”(S): 1.4 MPa

[0102] (2) Storage elastic modulus E’(S): 10.4 MPa

[0103] (3) Loss tangent tanδ(S) (E”(S) / E’(S)): 0.14

[0104] On the other hand, regarding the ratio of the thickness of the obtained stretchable wiring to the overall thickness of the stretchable device, the ratio of the cross-sectional area of the stretchable wiring to the overall cross-sectional area of the stretchable device, and the (1) loss elastic modulus E”(W), (2) storage elastic modulus E’(W), and (3) loss tangent tanδ of the stretchable wiring, they are the same as in Example 1.

[0105] Based on the above, the ratio of the loss elastic modulus E”(S) of the stretchable substrate to the loss elastic modulus E”(W) of the stretchable wiring is 0.05. The ratio of the storage elastic modulus E’(S) of the stretchable substrate to the storage elastic modulus E’(W) of the stretchable wiring is 0.06. In addition, the ratio of the loss tangent tanδ(S) of the stretchable substrate to the loss tangent tanδ(W) of the stretchable wiring is 0.78.

[0106] Under the above structure, the stretched wiring resistance (index) is 125 with respect to the wiring resistance (index) 100 before use (initial stage) of the stretchable device 100. Based on the above, the wiring resistance increase rate is +25%. In addition, as in Example 1, the stretchable device 100 can be stretched.

[0107] Example 8

[0108] In Example 8, compared with Example 1, as the stretchable substrate 10, a stretchable substrate having the (1) loss elastic modulus E”(S), (2) storage elastic modulus E’(S), and (3) loss tangent tanδ(S) (E”(S) / E’(S)) shown in Table 1 was selected.

[0109] (1) Loss elastic modulus E”(S): 0.6 MPa

[0110] (2) Storage elastic modulus E’(S): 7.8 MPa

[0111] (3) Loss tangent tanδ(S) (E”(S) / E’(S)): 0.08

[0112] On the other hand, regarding the ratio of the thickness of the obtained stretchable wiring to the overall thickness of the stretchable device, the ratio of the cross-sectional area of the stretchable wiring to the overall cross-sectional area of the stretchable device, and the (1) loss elastic modulus E”(W), (2) storage elastic modulus E’(W), and (3) loss tangent tanδ of the stretchable wiring, they are the same as in Example 1.

[0113] Based on the above, the ratio of the loss elastic modulus E”(S) of the stretchable substrate to the loss elastic modulus E”(W) of the stretchable wiring is 0.02. The ratio of the storage elastic modulus E’(S) of the stretchable substrate to the storage elastic modulus E’(W) of the stretchable wiring is 0.05. Additionally, the ratio of the loss tangent tanδ(S) of the stretchable substrate to the loss tangent tanδ(W) of the stretchable wiring is 0.45.

[0114] Under the above structure, the stretched wiring resistance (index) takes the wiring resistance (index) 100 before use (initial) of the stretchable device 100 as a reference and is 120. Based on the above, the wiring resistance increase rate is +20%. In addition, similar to Example 1, the stretchable device 100 can be stretched.

[0115] Comparative Example 1

[0116] Compared with Example 1, as the stretchable substrate, a stretchable substrate having the (1) loss elastic modulus E”(S), (2) storage elastic modulus E’(S), and (3) loss tangent tanδ(S) (E”(S) / E’(S)) shown in Table 1 was selected.

[0117] (1) Loss elastic modulus E”(S): 43.6 MPa

[0118] (2) Storage elastic modulus E’(S): 147.2 MPa

[0119] (3) Loss tangent tanδ(S) (E”(S) / E’(S)): 0.30

[0120] On the other hand, regarding the ratio of the thickness of the obtained stretchable wiring to the overall thickness of the stretchable device, the ratio of the cross-sectional area of the stretchable wiring to the overall cross-sectional area of the stretchable device, and the (1) loss elastic modulus E”(W), (2) storage elastic modulus E’(W), and (3) loss tangent tanδ of the stretchable wiring, they are the same as in Example 1.

[0121] Based on the above, the ratio of the loss modulus of elasticity E”(S) of the stretchable substrate to the loss modulus of elasticity E”(W) of the stretchable wiring is 1.52. The ratio of the storage modulus of elasticity E’(S) of the stretchable substrate to the storage modulus of elasticity E’(W) of the stretchable wiring is 0.91. Additionally, the ratio of the loss tangent tanδ(S) of the stretchable substrate to the loss tangent tanδ(W) of the stretchable wiring is 1.68.

[0122] Under the above structure, the stretched wiring resistance (index) is 220 with respect to 100 of the wiring resistance (index) before use (initial stage) of the stretchable device. Based on the above, the wiring resistance increase rate is +120%. In addition, similar to Example 1, the stretchable device can be stretched.

[0123] Comparative Example 2

[0124] Compared with Example 1, as the stretchable substrate for Comparative Example 2, a stretchable substrate having (1) a loss modulus of elasticity E”(S), (2) a storage modulus of elasticity E’(S), and (3) a loss tangent tanδ(S) (E”(S) / E’(S)) shown in Table 1 was selected.

[0125] (1) Loss modulus of elasticity E”(S): 69.9 MPa

[0126] (2) Storage modulus of elasticity E’(S): 659.5 MPa

[0127] (3) Loss tangent tanδ(S) (E”(S) / E’(S)): 0.11

[0128] On the other hand, regarding the ratio of the thickness of the obtained stretchable wiring to the overall thickness of the stretchable device, the ratio of the cross-sectional area of the stretchable wiring to the overall cross-sectional area of the stretchable device, and (1) the loss modulus of elasticity E”(W), (2) the storage modulus of elasticity E’(W), and (3) the loss tangent tanδ of the stretchable wiring, they are the same as in Example 1.

[0129] Based on the above, the ratio of the loss modulus of elasticity E”(S) of the stretchable substrate to the loss modulus of elasticity E”(W) of the stretchable wiring is 2.4. The ratio of the storage modulus of elasticity E’(S) of the stretchable substrate to the storage modulus of elasticity E’(W) of the stretchable wiring is 4.1. Additionally, the ratio of the loss tangent tanδ(S) of the stretchable substrate to the loss tangent tanδ(W) of the stretchable wiring is 0.6.

[0130] Under the above structure, in Comparative Example 2, compared with Example 1, the storage elastic modulus E’(S) of the stretchable substrate was about 35 times, so the stretchable substrate was relatively hard and could not stretch. As a result, the stretchable device could not be stretched.

[0131] Comparative Example 3

[0132] In Comparative Example 3, compared with Example 1, as the stretchable substrate, a stretchable substrate having (1) loss elastic modulus E”(S), (2) storage elastic modulus E’(S), and (3) loss tangent tanδ(S) (E”(S) / E’(S)) shown in Table 1 was selected.

[0133] (1) Loss elastic modulus E”(S): 272.4 MPa

[0134] (2) Storage elastic modulus E’(S): 3728.5 MPa

[0135] (3) Loss tangent tanδ(S) (E”(S) / E’(S)): 0.07

[0136] On the other hand, regarding the ratio of the thickness of the obtained stretchable wiring to the overall thickness of the stretchable device, the ratio of the cross-sectional area of the stretchable wiring to the overall cross-sectional area of the stretchable device, and (1) loss elastic modulus E”(W), (2) storage elastic modulus E’(W), and (3) loss tangent tanδ of the stretchable wiring, they were the same as in Example 1.

[0137] Based on the above, the ratio of the loss elastic modulus E”(S) of the stretchable substrate to the loss elastic modulus E”(W) of the stretchable wiring was 9.5. The ratio of the storage elastic modulus E’(S) of the stretchable substrate to the storage elastic modulus E’(W) of the stretchable wiring was 23.0. In addition, the ratio of the loss tangent tanδ(S) of the stretchable substrate to the loss tangent tanδ(W) of the stretchable wiring was 0.4.

[0138] Under the above structure, in Comparative Example 3, compared with Example 1, the storage elastic modulus E’(S) of the stretchable substrate was about 190 times, so the stretchable substrate was relatively hard and could not stretch. As a result, the stretchable device could not be stretched.

[0139] [Table 1]

[0140]

[0141] Based on the above content, it can be known that: When comparing Examples 1 to 8 and Comparative Example 1, in the stretchable device 100, if the loss elastic modulus E”(S) of the stretchable substrate 10 is smaller than the loss elastic modulus E”(W) of the stretchable wirings 20 and 30, the rising rate of the wiring resistance becomes 100% or less.

[0142] Specifically, it can be known that: If the ratio of the loss elastic modulus E”(S) of the stretchable substrate 10 to the loss elastic modulus E”(W) of the stretchable wirings 20 and 30 is less than 1, the rising rate of the wiring resistance becomes 100% or less.

[0143] The reason for this can be explained as follows: When the stretchable device stretches, the stretchable substrate is less likely to plastically deform compared to the stretchable wiring. That is, when stretching, the stretchable substrate is less likely to relax compared to the stretchable wiring. In addition, it can be explained as follows: From the viewpoint of ensuring the toughness of the stretchable substrate 10 itself, the above ratio is preferably 0.001 or more.

[0144] On the other hand, it can be known that: As shown in Comparative Examples 1 to 3, compared with Examples 1 to 8, in the stretchable device, if the loss elastic modulus E”(S) of the stretchable substrate is larger than the loss elastic modulus E”(W) of the stretchable wiring, the rising rate of the wiring resistance becomes 120%. In addition, it can be known that: As shown in Comparative Examples 2 and 3, compared with the examples, the storage elastic modulus E’(S) of the stretchable substrate is quite large (about 35 times or more), so it cannot stretch itself.

[0145] In addition, it can be known that: If the storage elastic modulus E’(S) of the stretchable substrate 10 is smaller than the storage elastic modulus E’(W) of the stretchable wirings 20 and 30, specifically, if the ratio of the storage elastic modulus E’(S) of the stretchable substrate 10 to the storage elastic modulus E’(W) of the stretchable wirings 20 and 30 is less than 1.0, the rising rate of the wiring resistance becomes 100% or less. The reason for this can be explained as follows: When the stretchable device stretches, the stretchable substrate is softer than the stretchable wiring.

[0146] In addition, it is known that: when the ratio of the loss elastic modulus E”(S) of the stretchable substrate to the loss elastic modulus E”(W) of the stretchable wiring is 0.1 or less, if the ratio of the loss tangent tanδ(S) of the stretchable substrate 10 to the loss tangent tanδ(W) of the stretchable wirings 20 and 30 is 1.5 or less (see Examples 4 to 8), then compared with Examples 1 to 3, the increase rate of the wiring resistance after repeated stretching can be appropriately suppressed. In addition, it is known that: if this ratio is 1.0 or less (see Examples 7 and 8), then compared with Examples 4 to 6, the increase rate of the wiring resistance after repeated stretching can be more appropriately suppressed. Moreover, it is known that: if this ratio is 0.5 or less (see Example 8), then compared with Examples 4 to 7, the increase rate of the wiring resistance after repeated stretching can be further appropriately suppressed.

[0147] Moreover, it is known that: in Example 2, when the ratio of the thickness / cross-sectional area of the stretchable wirings 20 and 30 to the overall thickness / overall cross-sectional area of the stretchable device 100 is 50%, the increase rate of the wiring resistance becomes +100%. In contrast, in Example 1, when this ratio is 30%, the increase rate of the wiring resistance becomes +50%. In addition, it is known that: in Example 3, when this ratio is 15%, the increase rate of the wiring resistance becomes +35%.

[0148] Based on the above, it is known that: if the proportion of the stretchable wiring in the entire stretchable device 100 based on thickness or cross-sectional area is set to a predetermined value or less (50% or less), then compared with Comparative Example 1, the increase rate of the wiring resistance can be set to +100% or less.

[0149] Similarly, it is known that: in Example 5, when the ratio of the thickness / cross-sectional area of the stretchable wirings 20 and 30 to the overall thickness / overall cross-sectional area of the stretchable device 100 is 50%, the increase rate of the wiring resistance becomes +60%. In contrast, in Example 4, when this ratio is 30%, the increase rate of the wiring resistance becomes +35%. In addition, it is known that: in Example 6, when this ratio is 15%, the increase rate of the wiring resistance becomes +20%.

[0150] Based on the above, it is also known that: if the proportion of the stretchable wiring in the entire stretchable device 100 based on thickness or cross-sectional area is set to a predetermined value or less (50% or less), then compared with Comparative Example 1, the increase rate of the wiring resistance can be set to +100% or less.

[0151] In addition, each embodiment and modification are illustrative, and the present invention is not limited to each embodiment and modification. In addition, each drawing is an illustration of the components and does not limit the shape. In addition, partial replacement or combination of the structures shown in different embodiments and modifications can be performed.

[0152] The stretchable device according to an embodiment of the present invention can be implemented in the following manner.

[0153] <1>

[0154] A stretchable device, wherein

[0155] the stretchable device includes a stretchable substrate and stretchable wiring disposed on the stretchable substrate,

[0156] the loss elastic modulus E”(S) of the stretchable substrate is smaller than the loss elastic modulus E”(W) of the stretchable wiring.

[0157] <2>

[0158] In the stretchable device according to <1>, the ratio of the loss elastic modulus E”(S) of the stretchable substrate to the loss elastic modulus E”(W) of the stretchable wiring is 0.001 or more and less than 1.

[0159] <3>

[0160] In the stretchable device according to <1> or <2>, the storage elastic modulus E’(S) of the stretchable substrate is smaller than the storage elastic modulus E’(W) of the stretchable wiring.

[0161] <4>

[0162] In the stretchable device according to <3>, the ratio of the storage elastic modulus E’(S) of the stretchable substrate to the storage elastic modulus E’(W) of the stretchable wiring is 0.001 or more and less than 1.

[0163] <5>

[0164] In the stretchable device according to any one of <2> to <4>, when the ratio of the loss elastic modulus E”(S) of the stretchable substrate to the loss elastic modulus E”(W) of the stretchable wiring is 0.1 or less, the ratio of the loss tangent tanδ(S) of the stretchable substrate to the loss tangent tanδ(W) of the stretchable wiring is 0.01 or more and 1.5 or less.

[0165] <6>

[0166] In the stretchable device according to any one of <1> to <5>, the ratio (%) of the thickness of the stretchable wiring to the overall thickness of the stretchable device is 50% or less.

[0167] <7>

[0168] In the stretchable device according to any one of <1> to <6>, the ratio (%) of the cross-sectional area of the stretchable wiring to the overall cross-sectional area of the stretchable device is 50% or less.

[0169] 100, 100A, 100B, stretchable device; 10, stretchable substrate; 20, first stretchable wiring; 30, second stretchable wiring; 40, coating layer; 10B, coating layer.

Claims

1. A stretchable device, wherein, the stretchable device includes a stretchable substrate and stretchable wirings disposed on the stretchable substrate, the loss elastic modulus E”(S) of the stretchable substrate is smaller than the loss elastic modulus E”(W) of the stretchable wirings.

2. The stretchable device according to claim 1, wherein, the ratio of the loss elastic modulus E”(S) of the stretchable substrate to the loss elastic modulus E”(W) of the stretchable wirings is 0.001 or more and less than 1.

3. The stretchable device according to claim 1 or 2, wherein, the storage elastic modulus E’(S) of the stretchable substrate is smaller than the storage elastic modulus E’(W) of the stretchable wirings.

4. The stretchable device according to claim 3, wherein, the ratio of the storage elastic modulus E’(S) of the stretchable substrate to the storage elastic modulus E’(W) of the stretchable wirings is 0.001 or more and less than 1.

0.

5. The stretchable device according to any one of claims 2 to 4, wherein, when the ratio of the loss elastic modulus E”(S) of the stretchable substrate to the loss elastic modulus E”(W) of the stretchable wirings is 0.1 or less, the ratio of the loss tangent tanδ(S) of the stretchable substrate to the loss tangent tanδ(W) of the stretchable wirings is 0.01 or more and 1.5 or less.

6. The stretchable device according to any one of claims 1 to 5, wherein, the ratio of the thickness of the stretchable wirings to the overall thickness of the stretchable device, expressed as a percentage, is 50% or less.

7. The stretchable device according to any one of claims 1 to 6, wherein, the ratio of the cross-sectional area of the stretchable wirings to the overall cross-sectional area of the stretchable device, expressed as a percentage, is 50% or less.

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