Stretchable device

Abstract

One embodiment of the present invention provides a stretchable device comprising a stretchable base material and a stretchable wiring disposed on the stretchable base material, wherein a loss elastic modulus E''(S) of the stretchable base material is smaller than a loss elastic modulus E''(W) of the stretchable wiring.

Description

stretchable devices

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

[0002] Stretchable devices including a stretchable substrate and stretchable wiring disposed on the stretchable substrate have been known for some time.

[0003] Japanese Patent Application Laid-Open No. 2020-181958

[0004] Here, the inventors of the present application have found that there are matters to be improved in the stretchable device in the following respects.

[0005] Specifically, in a stretchable device, the proportion of the stretchable substrate relative to the stretchable wiring is relatively large, which can result in a large contribution to the stretching behavior of the device as a whole. Therefore, if the stretchable substrate is prone to plastic deformation (i.e., prone to sagging) during stretching, this may cause the stretchable wiring arranged on the stretchable substrate to gradually stretch, which may increase the wiring resistance of the stretchable wiring.

[0006] For these reasons, it is desirable that the stretchable substrate, which is a component of the stretchable device, is resistant to plastic deformation when the device stretches.

[0007] Therefore, an object of the present invention is to provide a stretchable device including a stretchable substrate that is resistant to plastic deformation during stretching.

[0008] In order to achieve the above object, one embodiment of the present invention provides a stretchable device comprising a stretchable substrate and a stretchable wire disposed on the stretchable substrate, wherein the loss modulus E''(S) of the stretchable substrate is smaller than the loss modulus E''(W) of the stretchable wire.

[0009] According to a stretchable device according to one embodiment of the present invention, the stretchable substrate can be made less susceptible to plastic deformation during stretching.

[0010] Fig. 1 is a cross-sectional view schematically showing a stretchable device according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view schematically showing a stretchable device according to a second embodiment of the present invention. Fig. 3 is a cross-sectional view schematically showing a stretchable device according to a third embodiment of the present invention.

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each embodiment, differences from previous embodiments will be mainly described. In particular, similar effects resulting from similar configurations will not be mentioned in each embodiment. Among the components in the following embodiments, components not recited in independent claims will be described as optional components. Furthermore, the size and size ratios of components shown in the drawings are not necessarily strict. Furthermore, in each drawing, substantially identical components are assigned the same reference numerals, and duplicated descriptions may be omitted or simplified.

[0012] [First embodiment] Hereinafter, the configuration of a stretchable device 100 according to a first embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a cross-sectional view schematically showing the stretchable device according to the first embodiment of the present invention.

[0013] The stretchable device 100 according to the first embodiment of the present invention includes a stretchable substrate 10 and at least one stretchable wire disposed on the stretchable substrate 10. The at least one stretchable wire includes, for example, a first stretchable wire 20 and a second stretchable wire 30.

[0014] In this specification, "above" includes a state of being above an element at a distance, i.e., being above an element via another object, a state of being above an element with a gap, and a state of being directly above an element.

[0015] Therefore, in this specification, "stretchable wiring arranged on a stretchable substrate" includes a stretchable wiring in contact with the main surface of the stretchable substrate, and a stretchable wiring in a state where it is not in direct contact with the main surface of the stretchable substrate but is separated from the main surface via another member (for example, a resin layer described later).

[0016] The resin layer may be made of at least one resin material selected from the group consisting of polyimide resins, epoxy resins, urethane resins, and acrylic resins, or may be made of an inorganic material such as alumina or silicon dioxide.

[0017] The stretchable substrate is a sheet-like or film-like stretchable substrate made of, for example, a stretchable resin material, such as a styrene-based elastomer, an olefin-based elastomer, a urethane-based elastomer, or a silicone-based elastomer.

[0018] The thickness of the stretchable substrate is not particularly limited, but is preferably 100 μm or less, more preferably 50 μm or less, from the viewpoint of not inhibiting the stretching of the surface of the living body when attached to the living body. Furthermore, the thickness of the stretchable substrate is preferably 10 μm or more from the viewpoint of ensuring a predetermined strength.

[0019] Each of the elastic wires includes conductive particles and a resin. Examples of the elastic wires include a mixture of conductive particles such as metal powder of Ag, Cu, or Ni and a resin material such as an acrylic or silicone resin. 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. Furthermore, the conductive particles are preferably spherical.

[0020] The thickness of each elastic wire is not particularly limited, but is preferably 100 μm or less, and more preferably 50 μm or less. The thickness of each elastic wire is preferably 0.01 μm or more. The line width of each elastic wire is not particularly limited, but is preferably 0.1 μm or more, and more preferably 1 mm or less. The shape of each elastic wire is also not particularly limited.

[0021] Based on the above-mentioned configuration, the inventors of the present invention have conducted extensive research into solutions for providing a stretchable substrate that is resistant to plastic deformation during stretching of a stretchable device. As a result, the inventors have focused on the viscoelastic properties of each component of the stretchable device, rather than the structure or shape of the component, and have devised the present invention.

[0022] Specifically, the present invention is characterized in that in the stretchable device 100, the loss modulus E''(S) of the stretchable substrate 10 is smaller than the loss modulus E''(W) of the stretchable wirings 20, 30. The loss modulus as used herein refers to a measure of energy lost from components due to heat generation or the like during deformation, and refers to the degree of sagging of the stretchable substrate / stretchable wiring. The larger this value, the more likely the components are to sag, and the smaller this value, the less likely the components are to sag.

[0023] According to these characteristics, the loss modulus E'' (S) of the stretchable substrate 10 is smaller than the loss modulus E'' (W) of the stretchable wirings 20, 30, and therefore the stretchable substrate is less likely to undergo plastic deformation than the stretchable wirings when stretched. In other words, the stretchable substrate can be made less likely to sag than the stretchable wirings when stretched. This makes it possible to prevent the stretchable wirings 20, 30 arranged on the stretchable substrate 10 from gradually stretching, and as a result, it is possible to prevent an increase in the wiring resistance of the stretchable wirings 20, 30.

[0024] In the above, the ratio of the loss modulus E''(S) of the elastic substrate 10 to the loss modulus E''(W) of the elastic wiring 20, 30 is smaller than 1, in order to make the elastic substrate less susceptible to plastic deformation than the elastic wiring.

[0025] For example, the upper limit of the ratio may be, for example, 0.6 or less. From the viewpoint of making the stretchable substrate less susceptible to plastic deformation than the stretchable wiring, the upper limit of the ratio is preferably 0.1 or less, for example, 0.07, more preferably 0.05 or less, and even more preferably 0.02 or less.

[0026] In this embodiment, it is also preferable that the storage modulus E′(S) of the stretchable substrate 10 is smaller than the storage modulus E′(W) of the stretchable wirings 20 and 30 .

[0027] As used herein, the storage modulus refers to a measure of the energy stored in the components during deformation, and is a value that indicates the degree of hardness of the stretchable substrate / stretchable wiring. A larger value indicates that the components are relatively harder, and a smaller value indicates that the components are softer.

[0028] According to this feature, the stretchable substrate 10 can be selected to be relatively softer than the stretchable wirings 20, 30, making it less likely to interfere with the expansion of the stretchable wiring when the stretchable device 100 is stretched.

[0029] In the above, the ratio of the storage modulus E'(S) of the elastic substrate 10 to the storage modulus E'(W) of the elastic wiring 20, 30 is 0.001 or more from the viewpoint of ensuring the elastic function of the substrate 10 itself, and is smaller than 1.0 from the viewpoint of making it softer than the elastic wiring.

[0030] The upper limit of the ratio is preferably 0.5 or less, for example 0.2 or less, from the viewpoint of suitably softening the stretchable substrate 10. From the viewpoint of more suitably softening the stretchable substrate, the upper limit of the ratio is more preferably 0.1 or less, for example 0.06, and even more preferably 0.05 or less.

[0031] Specifically, the ratio of the loss tangent tanδ(S) of the stretchable substrate 10 to the loss tangent tanδ(W) of the stretchable wiring 20, 30 is 0.01 or more from the viewpoint of ensuring the viscoelasticity of the stretchable substrate / stretchable wiring, and is 6.0 or less from the viewpoint of suppressing the rate of increase in wiring resistance after repeated stretching to a predetermined level or less.

[0032] The loss tangent tanδ as used in this specification refers to the ratio of the loss modulus E″ of the stretchable wiring or stretchable substrate to the storage modulus E′ of the stretchable wiring or stretchable substrate, and indicates whether the elastic property or the viscous property is more pronounced in the deformation of a certain viscoelastic body.

[0033] In particular, when the ratio of the loss modulus E''(S) of the stretchable substrate to the loss modulus E''(W) of the stretchable wiring is 0.1 or less, the ratio of the loss tangent tanδ(S) of the stretchable substrate 10 to the loss tangent tanδ(W) of the stretchable wiring 20, 30 is preferably 1.5 or less, more preferably 1.0 or less, and even more preferably 0.5 or less, from the viewpoint of suitably suppressing the rate of increase in wiring resistance after repeated stretching.

[0034] Furthermore, on the premise that the loss modulus E''(S) of the stretchable substrate 10 is smaller than the loss modulus E''(W) of the stretchable wirings 20, 30, when the stretchable substrate 10 and the stretchable wirings 20, 30 have predetermined values, the following characteristics can be obtained. Specifically, it is preferable that the ratio of the thickness of the stretchable wirings 20, 30 to the total thickness of the stretchable device 100 is 50% or less.

[0035] According to this feature, it is possible to suppress an increase in wiring resistance that can occur when the proportion of the stretchable wiring in the entire stretchable device 100 is relatively high. From the viewpoint of suitably suppressing such an increase in wiring resistance, the thickness ratio of the above-mentioned stretchable wiring is more preferably 30% or less, and even more preferably 15% or less. Furthermore, from the viewpoint of ensuring the wiring function in the stretchable device 100, the thickness ratio of the above-mentioned stretchable wiring is preferably 5% or more.

[0036] Furthermore, in terms of the cross-sectional area, which may have a correlation with the thickness of the stretchable wiring, it is preferable that the ratio of the cross-sectional area of ​​the stretchable wirings 20, 30 to the total cross-sectional area of ​​the stretchable device 100 is 50% or less.

[0037] According to this feature, it is possible to suppress an increase in wiring resistance that can occur when the proportion of stretchable wiring in the entire stretchable device 100 is relatively high. From the viewpoint of suitably suppressing such an increase in wiring resistance, the ratio of the cross-sectional area of ​​the above-mentioned stretchable wiring is more preferably 30% or less, and even more preferably 15% or less. Furthermore, from the viewpoint of ensuring the wiring function in the stretchable device 100, the ratio of the cross-sectional area of ​​the above-mentioned stretchable wiring is preferably 2% or more.

[0038] The stretchable device 100 can be fabricated through the following steps. Specifically, first, a stretchable substrate 10 is prepared. The stretchable substrate 10 is selected to have a loss modulus E''(S) smaller than the loss modulus E''(W) of the stretchable wiring to be formed later.

[0039] Next, after preparing the stretchable substrate 10, continuous or separate wiring materials are screen-printed on the prepared stretchable substrate 10, and then dried. In this way, the stretchable wirings 20, 30 can be formed on the stretchable substrate 10. In this way, the above-mentioned stretchable device 100 can be produced.

[0040] [Second embodiment] A second embodiment will be described below. Fig. 2 is a cross-sectional view schematically showing a stretchable device according to a second embodiment of the present invention. The second embodiment differs from the first embodiment in that it further includes a covering layer 40 that covers the stretchable substrate 10 and the stretchable wirings 20, 30.

[0041] Even in this case, from the viewpoint of making the covering layer 40 less susceptible to plastic deformation than the stretchable wiring during stretching, it is preferable that the covering layer 40 have viscoelastic properties similar to those of the stretchable substrate 10. Specifically, in the stretchable device 100A, it is preferable that the loss modulus E''(S) of the covering layer 40 is smaller than the loss modulus E''(W) of the stretchable wirings 20, 30. It should be noted that in the second embodiment, the stretchable substrate 10 and the covering layer 40 do not need to have the same material composition.

[0042] This makes it possible to make both the stretchable substrate 10 and the covering layer 40 less susceptible to plastic deformation at substantially the same level than the stretchable wiring during stretching. As a result, for the stretchable device 100A as a whole, even if the covering layer 40 is present, an increase in the wiring resistance of the stretchable wirings 20, 30 can be suitably suppressed.

[0043] Third Embodiment The following describes the third embodiment. The third embodiment differs from the first embodiment in that it further includes a covering layer 10B that covers the stretchable substrate 10 and the stretchable wires 20, 30.

[0044] This covering layer 10B can have the same function as the covering layer 40 in the second embodiment described above. Note that in the third embodiment, the stretchable substrate 10 and the covering layer 10B can have the same material composition. Therefore, it is possible to make both the stretchable substrate 10 and the covering layer 10B less susceptible to plastic deformation at the same level than the stretchable wiring during stretching. As a result, for the stretchable device 100B as a whole, even if the covering layer 10B is present, it is possible to more suitably suppress an increase in the wiring resistance of the stretchable wirings 20, 30.

[0045] Examples of the present invention will be described below.

[0046] Example 1 First, a stretchable substrate 10 was prepared. The stretchable substrate 10 was selected to have a loss modulus E''(S) smaller than the loss modulus E''(W) of the stretchable wiring to be formed later. Specifically, a styrene-based elastomer was prepared as the stretchable substrate 10.

[0047] The elastic substrate 10 selected had the following properties: (1) loss modulus E''(S), (2) storage modulus E'(S), and (3) loss tangent tan δ(S) (E''(S) / E'(S)) shown in Table 1. (1) Loss modulus E''(S): 15.9 MPa (2) Storage modulus E'(S): 19.4 MPa (3) Loss tangent tan δ(S) (E''(S) / E'(S)): 0.90

[0048] The wiring material used was a mixture of Ag particles and an acrylic resin containing Ag particles. This wiring material had a material composition that would result in an elastic wiring having the following properties after device fabrication: (1) loss modulus E''(W), (2) storage modulus E'(W), and (3) loss tangent tan δ(W) (E''(W) / E'(W)) shown in Table 1. (1) Loss modulus E''(W): 28.7 MPa (2) Storage modulus E'(W): 162.3 MPa (3) Loss tangent tan δ(W) (E''(W) / E'(W)): 0.18

[0049] A wiring material was screen-printed on the prepared stretchable substrate 10, and then dried using a drying device. In this way, a stretchable device 100 including the stretchable substrate 10 and the stretchable wirings 20, 30 formed on the stretchable substrate was produced (see FIG. 1 ).

[0050] The (1) loss modulus E'', (2) storage modulus E', and (3) loss tangent tanδ (E'' / E') of the above-mentioned stretchable substrate 10 and stretchable wirings 20, 30 were measured using a dynamic viscoelasticity measuring device (RSA-G2 manufactured by TA Instruments). Specifically, the stretchable substrate was vibrated up and down to deform and impart strain, and the above-mentioned (1) loss modulus E'' and (2) storage modulus E' were measured from the waveform of shear stress as a response and the phase difference therebetween. Furthermore, the (3) loss tangent tanδ (E'' / E') was calculated from these measured values.

[0051] From the above, the ratio of the loss modulus E''(S) of the stretchable substrate to the loss modulus E''(W) of the stretchable wire was 0.56. The ratio of the storage modulus E'(S) of the stretchable substrate to the storage modulus E'(W) of the stretchable wire was 0.12. In addition, the ratio of the loss tangent tan δ(S) of the stretchable substrate to the loss tangent tan δ(W) of the stretchable wire was 5.08.

[0052] In this Example 1, the thickness of the stretchable wiring was 30 μm, and the total thickness of the stretchable device was 100 μm in the fabricated stretchable device 100. Furthermore, in the fabricated stretchable device 100, the cross-sectional area of ​​the thickness of the stretchable wiring was 30% of the total cross-sectional area of ​​the stretchable device.

[0053] [Measurement of wiring resistance before and after use of the device, measurement of the rate of increase in wiring resistance, and determination of whether stretching is possible] Under the above configuration, the wiring resistance of the stretchable wiring before use (initial stage) of the stretchable device 100 was measured by a four-terminal measurement method. In this example, the wiring resistance at this time was set to 100 (index) as the reference. Furthermore, the wiring resistance of the stretchable wiring was measured after the wiring was stretched by 10% and stretched 70 times. The wiring resistance (index) at this time was 150, with the wiring resistance (index) of 100 before use (initial stage) of the stretchable device 100 as the reference. From the above, the rate of increase in wiring resistance was +50%. Furthermore, in this Example 1, the stretchable device 100 was able to stretch.

[0054] In addition to this Example 1, in the following Examples 2 to 8, those in which the rate of increase in wiring resistance is +100% or less are treated as Examples, and those in which the rate of increase in wiring resistance is greater than +100% are treated as Comparative Examples.

[0055] The following description of the second and subsequent embodiments will focus on differences from the first embodiment. Descriptions that overlap with the description of the first embodiment will be omitted or omitted.

[0056] As shown in Table 1, Example 2 differs from Example 1 in that the ratio of the thickness of the stretchable wire to the total thickness of the obtained stretchable device and the ratio of the cross-sectional area of ​​the stretchable wire to the total cross-sectional area of ​​the stretchable device were each changed from 30% to 50%. On the other hand, the ratio of the loss modulus, the ratio of the storage modulus, and the ratio of the loss tangent of the stretchable wire and the stretchable substrate were the same as those in Example 1.

[0057] Under the above configuration, the wiring resistance (index) after stretching was 200, with the wiring resistance (index) before use (initial stage) of the stretchable device 100 being 100 as the reference. From the above, the rate of increase in wiring resistance was +100%. Note that, similar to Example 1, the stretchable device 100 was able to stretch.

[0058] As shown in Table 1, Example 3 differs from Example 1 in that the ratio of the thickness of the stretchable wire to the total thickness of the obtained stretchable device and the ratio of the cross-sectional area of ​​the stretchable wire to the total cross-sectional area of ​​the stretchable device were each changed from 30% to 15%. On the other hand, the ratio of the loss modulus, the ratio of the storage modulus, and the ratio of the loss tangent of the stretchable wire and the stretchable substrate were the same as those in Example 1.

[0059] Under the above configuration, the wiring resistance (index) after stretching was 135, with the wiring resistance (index) before use (initial stage) of the stretchable device 100 being 100 as the reference. From the above, the rate of increase in wiring resistance was +35%. Note that, similar to Example 1, the stretchable device 100 was able to stretch.

[0060] Example 4 In Example 4, compared to Example 1, the elastic substrate 10 selected had the following values: (1) loss modulus E''(S), (2) storage modulus E'(S), and (3) loss tangent tan δ(S) (E''(S) / E'(S)) shown in Table 1. (1) Loss modulus E''(S): 1.9 MPa (2) Storage modulus E'(S): 10.2 MPa (3) Loss tangent tan δ(S) (E''(S) / E'(S)): 0.19

[0061] On the other hand, the ratio of the thickness of the stretchable wiring to the total thickness of the obtained stretchable device, the ratio of the cross-sectional area of ​​the stretchable wiring to the total cross-sectional area of ​​the stretchable device, and (1) the loss modulus E″(W), (2) the storage modulus E′(W), and (3) the loss tangent tanδ of the stretchable wiring were the same as in Example 1.

[0062] From the above, the ratio of the loss modulus E''(S) of the stretchable substrate to the loss modulus E''(W) of the stretchable wire was 0.07. The ratio of the storage modulus E'(S) of the stretchable substrate to the storage modulus E'(W) of the stretchable wire was 0.06. In addition, the ratio of the loss tangent tan δ(S) of the stretchable substrate to the loss tangent tan δ(W) of the stretchable wire was 1.06.

[0063] Under the above configuration, the wiring resistance (index) after stretching was 135, with the wiring resistance (index) before use (initial stage) of the stretchable device 100 being 100 as the reference. From the above, the rate of increase in wiring resistance was +35%. Note that, similar to Example 1, the stretchable device 100 was able to stretch.

[0064] The following description of the fifth and subsequent embodiments will focus on differences from the fourth embodiment. Descriptions that overlap with the description of the fourth embodiment will be omitted or omitted.

[0065] As shown in Table 1, Example 5 differs from Example 4 in that the ratio of the thickness of the stretchable wire to the total thickness of the obtained stretchable device and the ratio of the cross-sectional area of ​​the stretchable wire to the total cross-sectional area of ​​the stretchable device were each changed from 30% to 50%. On the other hand, the ratio of the loss modulus, the ratio of the storage modulus, and the ratio of the loss tangent of the stretchable wire and the stretchable substrate were the same as those of Example 4.

[0066] Under the above configuration, the wiring resistance (index) after stretching was 160, with the wiring resistance (index) before use (initial stage) of the stretchable device 100 being 100 as the reference. From the above, the rate of increase in wiring resistance was +60%. Note that, similar to Example 1, the stretchable device 100 was able to stretch.

[0067] As shown in Table 1, Example 6 differs from Example 4 in that the ratio of the thickness of the stretchable wire to the total thickness of the obtained stretchable device and the ratio of the cross-sectional area of ​​the stretchable wire to the total cross-sectional area of ​​the stretchable device were each changed from 30% to 15%. On the other hand, the ratio of the loss modulus, the ratio of the storage modulus, and the ratio of the loss tangent of the stretchable wire and the stretchable substrate were the same as those of Example 4.

[0068] Under the above configuration, the wiring resistance (index) after stretching was 120, with the wiring resistance (index) before use (initial stage) of the stretchable device 100 being 100 as the reference. From the above, the rate of increase in wiring resistance was +20%. Note that, similar to Example 1, the stretchable device 100 was able to stretch.

[0069] The following description of the seventh and subsequent embodiments will focus on differences from the first embodiment. Descriptions that overlap with the description of the first embodiment will be omitted or omitted.

[0070] Example 7 In Example 7, compared to Example 1, the elastic substrate 10 selected had the following values: (1) loss modulus E''(S), (2) storage modulus E'(S), and (3) loss tangent tan δ(S) (E''(S) / E'(S)) shown in Table 1. (1) Loss modulus E''(S): 1.4 MPa (2) Storage modulus E'(S): 10.4 MPa (3) Loss tangent tan δ(S) (E''(S) / E'(S)): 0.14

[0071] On the other hand, the ratio of the thickness of the stretchable wiring to the total thickness of the obtained stretchable device, the ratio of the cross-sectional area of ​​the stretchable wiring to the total cross-sectional area of ​​the stretchable device, and (1) the loss modulus E″(W), (2) the storage modulus E′(W), and (3) the loss tangent tanδ of the stretchable wiring were the same as in Example 1.

[0072] From the above, the ratio of the loss modulus E''(S) of the stretchable substrate to the loss modulus E''(W) of the stretchable wire was 0.05. The ratio of the storage modulus E'(S) of the stretchable substrate to the storage modulus E'(W) of the stretchable wire was 0.06. In addition, the ratio of the loss tangent tan δ(S) of the stretchable substrate to the loss tangent tan δ(W) of the stretchable wire was 0.78.

[0073] Under the above configuration, the wiring resistance (index) after stretching was 125, with the wiring resistance (index) before use (initial stage) of the stretchable device 100 being 100 as the reference. From the above, the rate of increase in wiring resistance was +25%. Note that, similar to Example 1, the stretchable device 100 was able to stretch.

[0074] Example 8 In Example 8, compared to Example 1, the elastic substrate 10 selected had the following values: (1) loss modulus E''(S), (2) storage modulus E'(S), and (3) loss tangent tan δ(S) (E''(S) / E'(S)) shown in Table 1. (1) Loss modulus E''(S): 0.6 MPa (2) Storage modulus E'(S): 7.8 MPa (3) Loss tangent tan δ(S) (E''(S) / E'(S)): 0.08

[0075] On the other hand, the ratio of the thickness of the stretchable wiring to the total thickness of the obtained stretchable device, the ratio of the cross-sectional area of ​​the stretchable wiring to the total cross-sectional area of ​​the stretchable device, and (1) the loss modulus E″(W), (2) the storage modulus E′(W), and (3) the loss tangent tanδ of the stretchable wiring were the same as in Example 1.

[0076] From the above, the ratio of the loss modulus E''(S) of the stretchable substrate to the loss modulus E''(W) of the stretchable wire was 0.02. The ratio of the storage modulus E'(S) of the stretchable substrate to the storage modulus E'(W) of the stretchable wire was 0.05. In addition, the ratio of the loss tangent tan δ(S) of the stretchable substrate to the loss tangent tan δ(W) of the stretchable wire was 0.45.

[0077] Under the above configuration, the wiring resistance (index) after stretching was 120, with the wiring resistance (index) before use (initial stage) of the stretchable device 100 being 100 as the reference. From the above, the rate of increase in wiring resistance was +20%. Note that, similar to Example 1, the stretchable device 100 was able to stretch.

[0078] Comparative Example 1 In Comparative Example 1, compared to Example 1, an elastic substrate was selected that had the following values ​​as shown in Table 1: (1) loss modulus E''(S), (2) storage modulus E'(S), and (3) loss tangent tan δ(S) (E''(S) / E'(S)). (1) Loss modulus E''(S): 43.6 MPa (2) Storage modulus E'(S): 147.2 MPa (3) Loss tangent tan δ(S) (E''(S) / E'(S)): 0.30

[0079] On the other hand, the ratio of the thickness of the stretchable wiring to the total thickness of the obtained stretchable device, the ratio of the cross-sectional area of ​​the stretchable wiring to the total cross-sectional area of ​​the stretchable device, and (1) the loss modulus E″(W), (2) the storage modulus E′(W), and (3) the loss tangent tanδ of the stretchable wiring were the same as in Example 1.

[0080] From the above, the ratio of the loss modulus E''(S) of the stretchable substrate to the loss modulus E''(W) of the stretchable wire was 1.52. The ratio of the storage modulus E'(S) of the stretchable substrate to the storage modulus E'(W) of the stretchable wire was 0.91. In addition, the ratio of the loss tangent tan δ(S) of the stretchable substrate to the loss tangent tan δ(W) of the stretchable wire was 1.68.

[0081] Under the above configuration, the wiring resistance (index) after stretching was 220, with the wiring resistance (index) before use (initial stage) of the stretchable device being 100 as the reference. From the above, the wiring resistance increase rate was +120%. Note that, as in Example 1, the stretchable device was able to stretch.

[0082] Comparative Example 2 In Comparative Example 2, compared to Example 1, an elastic substrate was selected that had the following values: (1) loss modulus E''(S), (2) storage modulus E'(S), and (3) loss tangent tan δ(S) (E''(S) / E'(S)) shown in Table 1. (1) Loss modulus E''(S): 69.9 MPa (2) Storage modulus E'(S): 659.5 MPa (3) Loss tangent tan δ(S) (E''(S) / E'(S)): 0.11

[0083] On the other hand, the ratio of the thickness of the stretchable wiring to the total thickness of the obtained stretchable device, the ratio of the cross-sectional area of ​​the stretchable wiring to the total cross-sectional area of ​​the stretchable device, and (1) the loss modulus E″(W), (2) the storage modulus E′(W), and (3) the loss tangent tanδ of the stretchable wiring were the same as in Example 1.

[0084] From the above, the ratio of the loss modulus E''(S) of the stretchable substrate to the loss modulus E''(W) of the stretchable wire was 2.4. The ratio of the storage modulus E'(S) of the stretchable substrate to the storage modulus E'(W) of the stretchable wire was 4.1. In addition, the ratio of the loss tangent tan δ(S) of the stretchable substrate to the loss tangent tan δ(W) of the stretchable wire was 0.6.

[0085] Under the above configuration, in Comparative Example 2, the storage modulus E'(S) of the stretchable substrate was about 35 times that of Example 1, so the stretchable substrate was relatively hard and could not stretch. As a result, it was impossible to stretch the stretchable device.

[0086] Comparative Example 3 In Comparative Example 3, compared to Example 1, an elastic substrate was selected that had the following values: (1) loss modulus E″(S), (2) storage modulus E′(S), and (3) loss tangent tanδ(S) (E″(S) / E′(S)) shown in Table 1. (1) Loss modulus E″(S): 272.4 MPa (2) Storage modulus E′(S): 3728.5 MPa (3) Loss tangent tanδ(S) (E″(S) / E′(S)): 0.07

[0087] On the other hand, the ratio of the thickness of the stretchable wiring to the total thickness of the obtained stretchable device, the ratio of the cross-sectional area of ​​the stretchable wiring to the total cross-sectional area of ​​the stretchable device, and (1) the loss modulus E″(W), (2) the storage modulus E′(W), and (3) the loss tangent tanδ of the stretchable wiring were the same as in Example 1.

[0088] From the above, the ratio of the loss modulus E''(S) of the stretchable substrate to the loss modulus E''(W) of the stretchable wire was 9.5. The ratio of the storage modulus E'(S) of the stretchable substrate to the storage modulus E'(W) of the stretchable wire was 23.0. In addition, the ratio of the loss tangent tan δ(S) of the stretchable substrate to the loss tangent tan δ(W) of the stretchable wire was 0.4.

[0089] Under the above configuration, in Comparative Example 3, the storage modulus E'(S) of the stretchable substrate was about 190 times that of Example 1, so the stretchable substrate was relatively harder and could not stretch. As a result, the stretchable device could not stretch.

[0090] [Table 1]

[0091] From the above, when comparing Examples 1 to 8 with Comparative Example 1, it was found that in the stretchable device 100, when the loss modulus E''(S) of the stretchable substrate 10 is smaller than the loss modulus E''(W) of the stretchable wirings 20, 30, the rate of increase in wiring resistance is +100% or less.

[0092] Specifically, it was found that when the ratio of the loss modulus E''(S) of the elastic substrate 10 to the loss modulus E''(W) of the elastic wiring 20, 30 is less than 1, the increase rate of wiring resistance is +100% or less.

[0093] This is understood to be due to the fact that the stretchable substrate is less likely to plastically deform than the stretchable wiring when the stretchable device is stretched and contracted, i.e., the stretchable substrate is less likely to sag than the stretchable wiring when the stretchable device is stretched and contracted. Note that, from the viewpoint of ensuring the tenacity of the stretchable substrate 10 itself, it is understood that the above ratio is preferably 0.001 or more.

[0094] On the other hand, as shown in Comparative Examples 1 to 3, compared to Examples 1 to 8, it was found that in a stretchable device, when the loss modulus E''(S) of the stretchable substrate is larger than the loss modulus E''(W) of the stretchable wiring, the increase rate of the wiring resistance is +120%. Furthermore, as shown in Comparative Examples 2 and 3, compared to the Examples, it was found that the storage modulus E'(S) of the stretchable substrate was considerably larger (about 35 times or more), and therefore stretching itself was not possible.

[0095] Furthermore, it was found that when the storage modulus E'(S) of the stretchable substrate 10 is smaller than the storage modulus E'(W) of the stretchable wirings 20, 30, specifically when the ratio of the storage modulus E'(S) of the stretchable substrate 10 to the storage modulus E'(W) of the stretchable wirings 20, 30 is smaller than 1.0, the rate of increase in wiring resistance becomes +100% or less. This is understood to be due to the fact that the stretchable substrate becomes softer than the stretchable wiring when the stretchable device stretches.

[0096] Furthermore, when the ratio of the loss modulus E''(S) of the stretchable substrate to the loss modulus E''(W) of the stretchable wiring is 0.1 or less, and the ratio of the loss tangent tan δ(S) of the stretchable substrate 10 to the loss tangent tan δ(W) of the stretchable wiring 20, 30 is 1.5 or less (see Examples 4 to 8), it has been found that the rate of increase in wiring resistance after repeated stretching can be suitably suppressed compared to Examples 1 to 3. Furthermore, when this ratio is 1.0 or less (see Examples 7 and 8), it has been found that the rate of increase in wiring resistance after repeated stretching can be more suitably suppressed compared to Examples 4 to 6. Furthermore, when this ratio is 0.5 or less (see Example 8), it has been found that the rate of increase in wiring resistance after repeated stretching can be even more suitably suppressed compared to Examples 4 to 7.

[0097] Furthermore, in Example 2, when the ratio of the thickness / cross-sectional area of ​​the stretchable wirings 20, 30 to the total thickness / total cross-sectional area of ​​the stretchable device 100 was 50%, the rate of increase in wiring resistance was +100%, whereas in Example 1, when this ratio was 30%, the rate of increase in wiring resistance was +50%. Furthermore, in Example 3, when this ratio was 15%, the rate of increase in wiring resistance was +35%.

[0098] From the above, it was found that if the proportion of 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), the rate of increase in wiring resistance can be made +100% or less compared to Comparative Example 1.

[0099] Similarly, in Example 5, when the ratio of the thickness / cross-sectional area of ​​the stretchable wirings 20, 30 to the total thickness / total cross-sectional area of ​​the stretchable device 100 was 50%, the rate of increase in wiring resistance was +60%, whereas in Example 4, when this ratio was 30%, the rate of increase in wiring resistance was +35%. Furthermore, in Example 6, when this ratio was 15%, the rate of increase in wiring resistance was +20%.

[0100] From the above, it was found 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), the rate of increase in wiring resistance can be made +100% or less compared to Comparative Example 1.

[0101] Note that each embodiment and modification is an example, and the present invention is not limited to each embodiment and modification. Also, each drawing is an example of components, and does not limit the shape. Furthermore, partial substitution or combination of the configurations shown in different embodiments and modifications is possible.

[0102] A stretchable device according to an embodiment of the present invention may take the following forms. <1> A stretchable device comprising a stretchable substrate and a stretchable wiring arranged on the stretchable substrate, wherein the loss modulus E''(S) of the stretchable substrate is smaller than the loss modulus E''(W) of the stretchable wiring. <2> The stretchable device according to <1>, wherein the ratio of the loss modulus E''(S) of the stretchable substrate to the loss modulus E''(W) of the stretchable wiring is 0.001 or more and smaller than 1. <3> The stretchable device according to <1> or <2>, wherein the storage modulus E'(S) of the stretchable substrate is smaller than the storage modulus E'(W) of the stretchable wiring. <4> The stretchable device according to <3>, wherein the ratio of the storage modulus E'(S) of the stretchable substrate to the storage modulus E'(W) of the stretchable wiring is 0.001 or more and smaller than 1. <5> The stretchable device according to any one of <2> to <4>, wherein, when the ratio of the loss modulus E''(S) of the stretchable substrate to the loss modulus E''(W) of the stretchable wire 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 wire is 0.01 or more and 1.5 or less. <6> The stretchable device according to any one of <1> to <5>, wherein the ratio (%) of the thickness of the stretchable wire to the total thickness of the stretchable device is 50% or less. <7> The stretchable device according to any one of <1> to <6>, wherein the ratio (%) of the cross-sectional area of ​​the stretchable wire to the total cross-sectional area of ​​the stretchable device is 50% or less.

[0103] 100, 100A, 100B: Stretchable device 10: Stretchable substrate 20: First stretchable wiring 30: Second stretchable wiring 40: Covering layer 10B: Covering layer

Claims

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

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

3. The stretchable device according to claim 1, wherein the storage modulus E'(S) of the stretchable substrate is smaller than the storage modulus E'(W) of the stretchable wiring.

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

0.

5. 3. The stretchable device according to claim 2, wherein when the ratio of the loss modulus E″(S) of the stretchable substrate to the loss modulus E″(W) of the stretchable wiring is 0.1 or less, the ratio of the loss tangent tan δ(S) of the stretchable substrate to the loss tangent tan δ(W) of the stretchable wiring is 0.01 or more and 1.5 or less.

6. The stretchable device according to claim 1, wherein the ratio (%) of the thickness of the stretchable wiring to the total thickness of the stretchable device is 50% or less.

7. The stretchable device according to claim 1, wherein the ratio (%) of the cross-sectional area of ​​the stretchable wiring to the total cross-sectional area of ​​the stretchable device is 50% or less.