JP2020057775A - Stretchable wiring board and wearable device - Google Patents

Abstract

To provide a stretchable wiring board having excellent conductivity when a substrate is stretched.SOLUTION: A stretchable wiring board of the present invention includes a substrate 20 containing an elastomer, and wiring 10 being laminated on one surface of the substrate 20 and containing an elastomer and conductive fillers. The conductive fillers include scale-like metal powder (G). When A1 represents an average aspect of the conductive fillers at a cross section a1 obtained by cutting the wiring 10 in a thickness direction along a width direction, and A2 represents an average aspect of the conductive fillers at a cross section a2 obtained by cutting the wiring 10 in a direction orthogonal to the thickness direction, A1 and A2 being obtained by a predetermined procedure, A1 and A2 satisfy an expression: 1.1≤A1/A2.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a stretchable wiring board and a wearable device.

  In recent years, various developments have been made on materials used for wiring constituting a stretchable wiring board. As this type of technology, for example, a technology described in Patent Document 1 is known. Patent Literature 1 describes a conductive paste for producing a conductive film suitable for stretchable electrodes and wirings in which agglomerated silver powder is dispersed in a resin emulsion (see Table 1 of Patent Literature 1). 2 etc.).

JP 2015-79724 A

  However, the present inventor has studied and found that the conductive paste described in Patent Literature 1 has room for improvement in terms of conductivity when the substrate is stretched.

The present inventor has further studied and found that by appropriately selecting the orientation of the conductive filler containing the flaky metal powder (G), it is possible to control the electrical conductivity of the wiring during elongation.
As a result of intensive studies based on such knowledge, it has been found that the aspect A1 in the cross section a1 in the width direction of the wiring and the aspect A2 in the cross section a2 in the direction perpendicular to the thickness direction of the wiring are used as indices, so that the conductivity during elongation can be reduced. The inventors have found that the present invention can be stably evaluated, and have completed the present invention.

According to the present invention,
A substrate containing an elastomer;
Laminated on one surface of the substrate, and a wiring containing an elastomer and a conductive filler, and a stretchable wiring board having:
The conductive filler contains scaly metal powder (G),
The average aspect of the conductive filler in the cross section a1 when the wiring is cut in the thickness direction along the width direction, which is obtained based on the following procedures (1) to (3), is A1, and the wiring is in the thickness direction. Assuming that the average aspect of the conductive filler in the cross section a2 when cut in a direction perpendicular to the above is A2, A1 and A2 satisfy the following formula (I).
1.1 ≦ A1 / A2 Formula (I)
(procedure)
(1) A cross section obtained by cutting the wiring in the thickness direction along the width direction of the wiring is polished using an ion beam to obtain a cross section a1.
(2) The surface of the wiring is polished in the depth direction by 0.005 mm to 0.02 mm using an ion beam to obtain a cross section a2.
(3) Observation images are obtained using a scanning electron microscope (SEM) under the conditions of a visual field area of 128 μm × 102 μm and a magnification of 1000 times for each of the obtained cross sections a1 and a2. When taking a histogram of the obtained observation image by gradation versus pixel number, image analysis is performed based on the binarized image at the gradation that is the valley of two peaks, and the conductive filler The aspect of the orthogonal projection is measured, and the average value of the 30 measured values is calculated as the average aspect. The average aspect calculated from the cross section a1 is A1, and the average aspect calculated from the cross section a2 is A2.

  ADVANTAGE OF THE INVENTION According to this invention, the stretchable wiring board excellent in the electrical conductivity at the time of board | substrate extension, and a wearable device using the same are provided.

FIG. 1 is a cross-sectional view schematically illustrating an electronic device according to an embodiment. FIG. 4 is a cross-sectional view schematically illustrating a manufacturing process of the electronic device according to the embodiment. It is a perspective view which shows typically the outline | summary of the wiring board for demonstrating the measuring procedure of an aspect. 4 shows an SEM image of a cross section a1 in the wiring of Example 1. 4 shows an SEM image of a cross section a2 of the wiring of Example 1. 13 shows an SEM image of a cross section a1 in the wiring of Example 2. 13 shows an SEM image of a cross section a2 of the wiring of Example 2. 6 shows an SEM image of a cross section a1 of the wiring of Comparative Example 1. 9 shows an SEM image of a cross section a2 of the wiring of Comparative Example 1.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and description thereof will not be repeated. In the present specification, “to” means the following from the above unless otherwise specified.

An outline of the stretchable wiring board of the present embodiment will be described.
The stretchable wiring board according to the present embodiment includes a substrate containing an elastomer and a wiring laminated on one surface of the substrate and containing an elastomer and a conductive filler. The conductive filler in the wiring contains scale-like metal powder (G).
In this stretchable wiring substrate, the average aspect of the conductive filler in the cross section a1 when the wiring is cut in the thickness direction along the width direction, which is determined based on the following procedures (1) to (3), is A1, Assuming that the average aspect of the conductive filler in the cross section a2 when the wiring is cut in a direction perpendicular to the thickness direction is A2, A1 and A2 have characteristics that satisfy the following formula (I).
1.1 ≦ A1 / A2 Formula (I)

The procedure for measuring the aspect of the conductive filler contained in the wiring will be briefly described with reference to FIG. FIG. 3 is a perspective view showing an outline of the stretchable wiring board (wiring board 50). In FIG. 3, the wiring board 50 represents the “stretchable wiring board”, the wiring 10 represents the “wiring”, and the board 20 represents the “substrate”. In FIG. 3, an X axis, a Y axis, and a Z axis are orthogonal to each other in a three-dimensional space.
When the wiring 10 has a rectangular shape in a top view, the Z-axis direction means the thickness direction of the wiring, the X-axis direction means the short direction of the wiring 10, and the Y-axis direction means the long direction of the wiring 10.

(procedure)
(1) The wiring 10 is cut in the thickness direction (Z direction) along the width direction (X direction) of the wiring 10, that is, along the direction parallel to the width direction of the wiring 10, to obtain a cut surface. The wiring 10 can be cut so as to pass through a predetermined portion in the longitudinal direction (Y direction), for example, a central portion. The obtained cut surface is polished using an ion beam to obtain a cross section a1. The cross section a1 represents a cross section taken along the line a1-a1 in FIG.
As the cross section a1, a cross section cut in a direction orthogonal to the longitudinal direction of the wiring 10 or a cross section cut in a direction orthogonal to the extending direction of the wiring 10 may be used.
In the case where the top view of the wiring is a circular or square electrode pad, the cross section a1 may be a cross section passing through the center or near the center of the electrode pad in top view.
In this procedure, at least one portion of the cross section a1 in the portion extending in the predetermined direction of the wiring 10 or the electrode pad portion may be used.

(2) The surface 12 of the wiring 10 is polished to a predetermined depth of 0.005 mm to 0.02 mm in a depth direction (a direction opposite to the Z direction) using an ion beam to obtain a cross section a2. The cross section a2 represents a cross section taken along the line a2-a2 in FIG.
In the polishing method using the above-described ion beam, the surface of the object to be polished can be polished in the depth direction by argon ions accelerated by applying a voltage to the object to be polished in a reduced pressure / argon gas atmosphere. The ion beam can irradiate the surface from a vertical direction. The voltage amount and the time for applying the voltage, which are the conditions of the ion beam, can be appropriately selected depending on the object to be polished, the material of the wiring, and the wiring thickness. The predetermined depth to be polished in the above (2) means that the wiring 10 has been polished in a certain depth direction from the surface 12 of the wiring 10 and may be any of 0.005 mm to 0.02 mm. Note that the predetermined depth to be polished can allow variation in measurement accuracy.
In this procedure, at least one section a2 may be used on the surface 12 of the wiring 10 or the surface of the electrode pad. Further, the cross section a2 may be obtained from the wiring 10 targeted for the cross section a1.

(3) Subsequently, for each of the cross section a1 obtained in (1) and the cross section a2 obtained in (2), a scanning electron microscope (SEM) under the conditions of a visual field area: 128 μm × 102 μm and a magnification: 1000 × ) To obtain an observation image.
When a histogram is obtained from the obtained observation image in terms of gradation versus the number of pixels, image analysis is performed based on the image that has been binarized with the gradation that is the valley of the two peaks, and the positive The aspect of the projection is measured, and the average value of the 30 measured values is determined as the average aspect.
Assuming that the average aspect calculated from the cross section a1 is A1, and the average aspect calculated from the cross section a2 is A2, "A1 / A2" is calculated.

According to the knowledge of the present inventor, by appropriately controlling the orientation of the flaky metal powder (G) in the conductive filler, it is possible to improve the electrical conductivity at the time of elongation of the wiring in the stretchable wiring board. Was found.
By arranging the thin scale-like metal powders (G) so as to overlap each other in the cross section a1 in the width direction of the wiring, it is possible to secure many conductive paths when the wiring extends. On the other hand, in the cross section a2 in the direction orthogonal to the thickness direction of the wiring, the scale-like metal powder (G) having a large area is oriented, so that the resistance of the wiring can be reduced.
As a result of further study based on such knowledge, the orientation of the scaly metal powder (G) can be alternatively specified based on the aspect ratio of the orthogonal projection, and the aspect of the orthogonal projection can be specified. It has been found that by using the aspect ratios A1 and A2 in the cross sections a1 and a2 in the two directions based on the ratio as indices, it is possible to stably evaluate the electrical conductivity during elongation.

  The lower limit of the aspect ratio A1 / A2 is, for example, 1.1 or more, preferably 1.2 or more, and more preferably 1.3 or more. As a result, the flake-like metal powder (G) can be appropriately oriented as described above, so that the increase in the resistance value of the stretchable wiring board during extension can be suppressed to a low level, and the electrical conductivity during extension can be increased. Can be.

  The upper limit of the aspect ratio A1 / A2 is, for example, 20.0 or less, preferably 10.0 or less, more preferably 5.0 or less. As a result, the production stability of the thin wiring structure can be improved. Specifically, the scale-like metal powder (G) that is too long or too large may clog the mesh when printing the wiring, but this can be suppressed. In addition, if thinning is not possible, the distance between adjacent wirings is reduced, which may cause a short circuit, but this can be suppressed.

In the stretchable wiring board of the present embodiment, the aspect A1 of the conductive filler can satisfy the following formula (II).
2.0 ≦ A1 ≦ 10.0 Formula (II)

  The lower limit of the aspect A1 is, for example, 2.0 or more, preferably 2.2 or more, and more preferably 2.4 or more. As a result, an increase in the resistance value at the time of extension can be suppressed to a low level, so that the electrical conductivity at the time of extension can be increased. The upper limit of the aspect A1 is, for example, 10.0 or less, preferably 9.0 or less, and more preferably 8.0 or less. Thereby, the production stability of the wiring can be improved.

  The lower limit of the aspect A2 is, for example, 1.0 or more, preferably 1.3 or more, and more preferably 1.5 or more. Thereby, the initial resistance of the stretchable wiring board when it is not stretched can be reduced. The upper limit of the aspect A1 is, for example, 5.0 or less, preferably 4.0 or less, and more preferably 3.0 or less. Thereby, the production stability of the wiring can be improved.

  The stretchable wiring board of the present embodiment can have at least a part of the wiring the orientation property of the flaky metal powder (G) represented by the above aspect ratio A1 / A2. Further, the thinnest rewiring portion in the extending direction of the wiring may have the above-described alignment characteristics, and the electrode pad portion connected to another electrode may have the above-described alignment characteristics. This makes it possible to realize a stretchable wiring board having excellent electrical conductivity during elongation.

In the present embodiment, for example, the aspect ratio A1 / A1 is selected by appropriately selecting the type and amount of each component contained in the conductive paste as the wiring material, the method for preparing the conductive paste, the method for forming the wiring, and the like. It is possible to control A2, A1 and A2. Among these, for example, use of a large-area and thin-layered scale-like metal powder (G), as a solvent for the conductive paste, a solvent having a high boiling point suitable for printing, and solubility of an elastomer component such as silicone. Use of an excellent hydrocarbon-based solvent, appropriate adjustment of the amount of the solvent in the conductive paste, and the like are listed as factors for keeping the above-mentioned aspect ratios A1 / A2, A1, and A2 in a desired numerical range. Can be
Although the detailed mechanism is not clear, it is considered as follows.
By selecting a large scale-like metal powder (G) with a high aspect ratio and using a large amount of a solvent with good solubility of the solid silicone component, a conductive material with a relatively low viscosity before volatilization of the solvent In the paste, the scaly metal powder (G) has high dispersibility and can move freely. It is considered that the orientation of the scaly metal powder (G) can be appropriately controlled by using a printing means in the step of applying the conductive paste and adjusting the volatilization speed of the solvent to an appropriate level.

  Hereinafter, each configuration of the elastic wiring board of the present embodiment will be described.

  The stretchable wiring board of the present embodiment has at least a board containing an elastomer and a wiring containing an elastomer and a conductive filler. The substrate is insulative and one of the wires is conductive. Such a stretchable wiring board can exhibit appropriate stretchability and enhance stretchable electrical characteristics.

  The wiring may be made using a conductive paste. The conductive paste can include an elastomer composition, a conductive filler, and a solvent. In a wiring manufactured using the conductive paste, appropriate elasticity can be exhibited.

  The substrate may be made using an insulating paste. The insulating paste contains an elastomer composition and a solvent. A substrate manufactured using such an insulating paste can realize a substrate having excellent mechanical strength and insulating properties.

  The conductive paste can include an elastomer composition, a conductive filler, and a solvent. In a wiring made of a conductive paste, moderate elasticity can be exhibited.

  As the elastomer contained in the substrate or the wiring, for example, a silicone rubber, a urethane rubber, a thermosetting elastomer composition used to form one or more thermosetting elastomers selected from the group consisting of fluoro rubbers And preferably a silicone rubber-based curable composition.

(Elastomer)
In addition, as the elastomer, silicone rubber, urethane rubber, fluorine rubber, nitrile rubber, acrylic rubber, styrene rubber, chloroprene rubber, ethylene propylene rubber, or the like can be used. Among them, as the elastomer, one or more thermosetting elastomers selected from the group consisting of silicone rubber, urethane rubber, and fluoro rubber are used. As the elastomer, silicone rubber can be included from the viewpoint of being chemically stable and having excellent mechanical strength. The thermosetting elastomer can be composed of a cured product of the thermosetting elastomer composition. For example, the silicone rubber can be composed of a cured product of a silicone rubber-based curable composition. The thermoplastic elastomer can be constituted by a dried product of the thermoplastic elastomer composition.

  Hereinafter, an example in which the wiring according to the present embodiment is formed using a conductive paste containing a silicone rubber-based curable composition will be described.

  The silicone rubber-based curable composition of the present embodiment can contain a vinyl group-containing organopolysiloxane (A). The vinyl group-containing organopolysiloxane (A) is a polymer that is a main component of the silicone rubber-based curable composition of the present embodiment.

  The vinyl group-containing organopolysiloxane (A) can include a vinyl group-containing linear organopolysiloxane (A1) having a linear structure.

  The vinyl group-containing linear organopolysiloxane (A1) has a linear structure and contains a vinyl group, and the vinyl group serves as a crosslinking point during curing.

  The vinyl group content of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but is preferably, for example, two or more vinyl groups in the molecule and 15 mol% or less. , And more preferably 0.01 to 12 mol%. Thereby, the amount of the vinyl group in the vinyl group-containing linear organopolysiloxane (A1) is optimized, and it is possible to reliably form a network with each component described later. In the present embodiment, “to” means including numerical values at both ends.

  In addition, in this specification, the vinyl group content is mol% of the vinyl group-containing siloxane unit when all the units constituting the vinyl group-containing linear organopolysiloxane (A1) are 100 mol%. . However, it is considered that one vinyl group is contained per one vinyl group-containing siloxane unit.

  The degree of polymerization of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but is, for example, preferably in the range of about 1,000 to 10,000, and more preferably in the range of about 2,000 to 5,000. The degree of polymerization can be determined, for example, as the number average polymerization degree (or number average molecular weight) in terms of polystyrene by GPC (gel permeation chromatography) using chloroform as a developing solvent.

  Furthermore, the specific gravity of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but is preferably in the range of about 0.9 to 1.1.

  By using a vinyl group-containing linear organopolysiloxane (A1) having a degree of polymerization and specific gravity within the above ranges, the resulting silicone rubber has heat resistance, flame retardancy, chemical stability and the like. Can be improved.

  The vinyl group-containing linear organopolysiloxane (A1) is particularly preferably one having a structure represented by the following formula (1).

In the formula (1), R ¹ is a substituted or unsubstituted alkyl group, alkenyl group, aryl group having 1 to 10 carbon atoms, or a hydrocarbon group obtained by combining these. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among them, a methyl group is preferable. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, and a butenyl group, and among them, a vinyl group is preferable. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

R ² is a substituted or unsubstituted alkyl group, alkenyl group, aryl group having 1 to 10 carbon atoms, or a hydrocarbon group obtained by combining these. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among them, a methyl group is preferable. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, and a butenyl group. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

R ³ is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group obtained by combining these. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among them, a methyl group is preferable. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group.

Furthermore, examples of the substituent of R ¹ and R ^{2 in} the formula (1) include a methyl group and a vinyl group, and examples of the substituent of R ³ include a methyl group and the like.

In the formula (1), a plurality of R ¹ are independent of each other, and may be different from each other or may be the same. Further, the same applies to R ² and R ³ .

  Further, m and n are the number of repeating units constituting the vinyl group-containing linear organopolysiloxane (A1) represented by the formula (1), m is an integer of 0 to 2000, and n is 1000 to 10,000. Is an integer. m is preferably 0 to 1000, and n is preferably 2000 to 5000.

  The specific structure of the vinyl group-containing linear organopolysiloxane (A1) represented by the formula (1) includes, for example, those represented by the following formula (1-1).

In the formula (1-1), R ¹ and R ² are each independently a methyl group or a vinyl group, and at least one of them is a vinyl group.

  Further, as the vinyl group-containing linear organopolysiloxane (A1), the first vinyl group-containing linear group having two or more vinyl groups in the molecule and having a vinyl group content of 0.4 mol% or less is used. It contains a linear organopolysiloxane (A1-1) and a second vinyl group-containing linear organopolysiloxane (A1-2) having a vinyl group content of 0.5 to 15 mol%. Preferably it is. As raw rubber which is a raw material of silicone rubber, a first vinyl group-containing linear organopolysiloxane (A1-1) having a general vinyl group content and a second vinyl group-containing straight chain having a high vinyl group content are used. By combining with the chain organopolysiloxane (A1-2), the vinyl groups can be unevenly distributed, and the density of the crosslink density can be more effectively formed in the crosslink network of the silicone rubber. As a result, the tear strength of the silicone rubber can be more effectively increased.

Specifically, as the vinyl group-containing linear organopolysiloxane (A1), for example, in the above formula (1-1), a unit where R ¹ is a vinyl group and / or a unit where R ² is a vinyl group A first vinyl group-containing linear organopolysiloxane (A1-1) having two or more in the molecule and containing at most 0.4 mol%, and a unit wherein R ¹ is a vinyl group and / or R ^It is preferable to use a second vinyl group-containing linear organopolysiloxane (A1-2) containing 0.5 to 15 mol% of a unit in which ² is a vinyl group.

  In addition, the first vinyl group-containing linear organopolysiloxane (A1-1) preferably has a vinyl group content of 0.01 to 0.2 mol%, and 0.02 to 0.15 mol%. Is more preferred. The second vinyl group-containing linear organopolysiloxane (A1-2) preferably has a vinyl group content of 0.5 to 12 mol%, more preferably 0.8 to 8 mol%.

  Furthermore, when the first vinyl group-containing linear organopolysiloxane (A1-1) and the second vinyl group-containing linear organopolysiloxane (A1-2) are combined and compounded, (A1-1) The ratio between (A1-2) and (A1-2) is not particularly limited. For example, (A1-1) :( A1-2) is preferably 50:50 to 95: 5 by weight, and 60:40 to 92: 8, more preferably 80:20 to 90:10.

  The first and second vinyl group-containing linear organopolysiloxanes (A1-1) and (A1-2) may be used alone or in combination of two or more. Good.

  Further, the vinyl group-containing organopolysiloxane (A) may include a vinyl group-containing branched organopolysiloxane (A2) having a branched structure.

<< Organohydrogenpolysiloxane (B) >>
The silicone rubber-based curable composition of the present embodiment can contain an organohydrogenpolysiloxane (B).
The organohydrogenpolysiloxane (B) is classified into a linear organohydrogenpolysiloxane (B1) having a linear structure and a branched organohydrogenpolysiloxane (B2) having a branched structure. Either or both may be included.

  The straight-chain organohydrogenpolysiloxane (B1) has a straight-chain structure, has a structure in which hydrogen is directly bonded to Si (≡Si—H), and is a vinyl-containing organopolysiloxane (A). It is a polymer that undergoes a hydrosilylation reaction with a vinyl group contained in a silicone rubber-based curable composition, in addition to a vinyl group, to crosslink these components.

  Although the molecular weight of the linear organohydrogenpolysiloxane (B1) is not particularly limited, for example, the weight average molecular weight is preferably 20,000 or less, more preferably 1,000 or more and 10,000 or less.

  The weight average molecular weight of the linear organohydrogenpolysiloxane (B1) can be measured, for example, in terms of polystyrene by GPC (gel permeation chromatography) using chloroform as a developing solvent.

  The linear organohydrogenpolysiloxane (B1) is usually preferably one having no vinyl group. Thereby, it is possible to appropriately prevent the cross-linking reaction from proceeding in the molecule of the linear organohydrogenpolysiloxane (B1).

  As the linear organohydrogenpolysiloxane (B1) as described above, for example, those having a structure represented by the following formula (2) are preferably used.

In the formula (2), R ⁴ is a substituted or unsubstituted alkyl group, alkenyl group, aryl group having 1 to 10 carbon atoms, a hydrocarbon group obtained by combining these, or a hydride group. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among them, a methyl group is preferable. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, and a butenyl group. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

R ⁵ is a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, an alkenyl group, an aryl group, a hydrocarbon group obtained by combining these, or a hydride group. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among them, a methyl group is preferable. Examples of the alkenyl group having 1 to 10 carbon atoms include a vinyl group, an allyl group, and a butenyl group. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

In Formula (2), a plurality of R ⁴ are independent of each other, and may be different from each other or may be the same. The same is true for R ^5. However, at least two or more of a plurality of R ⁴ and R ⁵ are hydride groups.

R ⁶ is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group obtained by combining these. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among them, a methyl group is preferable. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group. A plurality of R ⁶ are independent of each other, and may be different from each other or may be the same.

As the R ^4, substituents R ^5, R ⁶ in the formula (2), for example, a methyl group, a vinyl group and the like, from the viewpoint of preventing the crosslinking reaction in the molecule is preferably a methyl group.

  Further, m and n are the number of repeating units constituting the linear organohydrogenpolysiloxane (B1) represented by the formula (2), where m is an integer of 2 to 150 and n is an integer of 2 to 150. It is. Preferably, m is an integer from 2 to 100 and n is an integer from 2 to 100.

  The linear organohydrogenpolysiloxane (B1) may be used alone or in combination of two or more.

  Since the branched organohydrogenpolysiloxane (B2) has a branched structure, it forms a region having a high crosslinking density, and is a component which greatly contributes to formation of a dense / dense structure of a crosslinking density in a silicone rubber system. Like the linear organohydrogenpolysiloxane (B1), it has a structure in which hydrogen is directly bonded to Si (≡Si—H). In addition to the vinyl group of the vinyl group-containing organopolysiloxane (A), silicone It is a polymer that undergoes a hydrosilylation reaction with a vinyl group of a component blended in a rubber-based curable composition to crosslink these components.

  The specific gravity of the branched organohydrogenpolysiloxane (B2) is in the range of 0.9 to 0.95.

  Further, it is preferable that the branched organohydrogenpolysiloxane (B2) generally has no vinyl group. This makes it possible to accurately prevent the cross-linking reaction from proceeding in the molecule of the branched organohydrogenpolysiloxane (B2).

  As the branched organohydrogenpolysiloxane (B2), those represented by the following average composition formula (c) are preferable.

Average composition formula (c)
(H _a (R ⁷ ) _3-a SiO _1/2 ) _m (SiO _4/2 ) _n
(In the formula (c), ^{R 7} is a monovalent organic group, a is 1 to 3 in the range of integers, m is ^{_{H a (R 7) 3-}} a number of _{SiO 1/2} units, n represents SiO _{4 / (2} units)

In the formula (c), R ⁷ is a monovalent organic group, and is preferably a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, an aryl group, or a hydrocarbon group obtained by combining these. Examples of the alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among them, a methyl group is preferable. Examples of the aryl group having 1 to 10 carbon atoms include a phenyl group.

  In the formula (c), a is the number of hydride groups (hydrogen atoms directly bonded to Si), and is an integer in the range of 1 to 3, preferably 1.

Further, in the equation (c), m is ^{_{H a (R 7) 3-}} a number of _{SiO 1/2} units, n is the number of _{SiO 4/2} units.

  The branched organohydrogenpolysiloxane (B2) has a branched structure. The linear organohydrogenpolysiloxane (B1) differs from the branched organohydrogenpolysiloxane (B2) in that the structure is linear or branched. The number (R / Si) of the alkyl groups R to be bonded is 1.8 to 2.1 for the linear organohydrogenpolysiloxane (B1), and 0.8 to 1 for the branched organohydrogenpolysiloxane (B2). .7.

  Since the branched organohydrogenpolysiloxane (B2) has a branched structure, for example, the amount of residues when heated to 1000 ° C. at a heating rate of 10 ° C./min in a nitrogen atmosphere is 5% or more. Becomes On the other hand, since the linear organohydrogenpolysiloxane (B1) is linear, the amount of the residue after heating under the above conditions is almost zero.

  Specific examples of the branched organohydrogenpolysiloxane (B2) include those having a structure represented by the following formula (3).

In the formula (3), R ⁷ is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, a hydrocarbon group obtained by combining these, or a hydrogen atom. Examples of the alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, and a propyl group, and among them, a methyl group is preferable. Examples of the aryl group having 1 to 8 carbon atoms include a phenyl group. Examples of the substituent of R ⁷ include a methyl group.

In Formula (3), a plurality of R ⁷ are independent of each other, and may be different from each other or may be the same.

  In the formula (3), “—O—Si≡” indicates that Si has a three-dimensionally branched structure.

  The branched organohydrogenpolysiloxane (B2) may be used alone or in combination of two or more.

  In the linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2), the amount of hydrogen atoms (hydride groups) directly bonded to Si is not particularly limited. However, in the silicone rubber-based curable composition, the linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane are used per mole of the vinyl group in the vinyl group-containing linear organopolysiloxane (A1). The total hydride group amount of the siloxane (B2) is preferably 0.5 to 5 mol, more preferably 1 to 3.5 mol. Thereby, a crosslinked network is reliably formed between the linear organohydrogenpolysiloxane (B1) and the branched organohydrogenpolysiloxane (B2) and the vinyl group-containing linear organopolysiloxane (A1). Can be done.

In this embodiment, the content of the elastomer composition (silicone rubber-based curable composition) in the conductive paste is preferably 1% by mass or more, and more preferably 3% by mass or more based on the entire conductive paste. More preferably, it is more preferably 5% by mass or more. Further, the content of the elastomer composition in the conductive paste is preferably 25% by mass or less, more preferably 20% by mass or less, and preferably 15% by mass or less based on the whole conductive paste. Is more preferable.
When the content of the elastomer composition is equal to or more than the lower limit, the wiring formed using the conductive paste can have appropriate flexibility. Further, by setting the content of the elastomer composition to the above upper limit or less, the mechanical strength of the wiring can be improved.

<< silica particles (C) >>
The silicone rubber-based curable composition of the present embodiment can contain silica particles (C) as necessary. Thereby, the hardness and mechanical strength of the elastomer formed from the silicone rubber-based curable composition can be improved.

  The conductive paste of the present embodiment contains silica particles in addition to the conductive filler, so that the mechanical strength and durability of an elastomer composed of a cured product of the conductive paste can be improved. By using such a conductive paste to form a conductive resin film such as wiring constituting a stretchable wiring board, the mechanical strength and durability of the conductive resin film can be improved. Thereby, the stretchable electrical characteristics of the stretchable wiring board including the wiring formed of the conductive paste of the present embodiment can be improved.

  The silica particles (C) are not particularly limited, but for example, fumed silica, calcined silica, precipitated silica and the like are used. These may be used alone or in combination of two or more.

Silica particles (C) are, for example, is preferably a specific surface area by the BET method, for example, 50 to 400 m ² / g, and more preferably 100 to 400 m ² / g. The average primary particle size of the silica particles (C) is, for example, preferably 1 to 100 nm, and more preferably about 5 to 20 nm.

  By using the silica particles (C) having a specific surface area and an average particle diameter within the above ranges, it is possible to improve the hardness and mechanical strength, particularly, the tensile strength of the formed silicone rubber.

In the present embodiment, the content of the silica particles (C) in the conductive paste is preferably 1% by mass or more, more preferably 2% by mass or more, based on the entire conductive paste. More preferably, it is at least 3% by mass. Further, the content of the silica particles (C) in the conductive paste is, for example, preferably 20% by mass or less, 15% by mass or less, and more preferably 12% by mass or less based on the whole of the conductive paste. Is more preferably 10% by mass or less.
When the content of the silica particles (C) is equal to or more than the lower limit, the elastomer of the wiring manufactured using the conductive paste can have appropriate mechanical strength. Further, when the content of the silica particles (C) is equal to or less than the above upper limit, the elastomer of the wiring can have appropriate conductive properties.

<< silane coupling agent (D) >>
The silicone rubber-based curable composition of the present embodiment can include a silane coupling agent (D).
The silane coupling agent (D) can have a hydrolyzable group. The hydrolyzable group is hydrolyzed by water to form a hydroxyl group, and the hydroxyl group undergoes a dehydration condensation reaction with a hydroxyl group on the surface of the silica particle (C), whereby the surface modification of the silica particle (C) can be performed.

  The silane coupling agent (D) may include a silane coupling agent having a hydrophobic group. This imparts the hydrophobic group to the surface of the silica particles (C), so that the cohesive force of the silica particles (C) decreases in the silicone rubber-based curable composition and thus in the silicone rubber (hydrogen due to silanol groups). Aggregation due to bonding is reduced), and as a result, it is presumed that the dispersibility of the silica particles in the silicone rubber-based curable composition is improved. Thereby, the interface between the silica particles and the rubber matrix increases, and the reinforcing effect of the silica particles increases. Further, it is presumed that when the rubber is deformed into the matrix, the slipperiness of the silica particles in the matrix is improved. And the mechanical strength (for example, tensile strength, tear strength, etc.) of the silicone rubber by the silica particles (C) is improved by improving the dispersibility and the slipperiness of the silica particles (C).

  Further, the silane coupling agent (D) can include a silane coupling agent having a vinyl group. Thereby, a vinyl group is introduced into the surface of the silica particles (C). Therefore, when the silicone rubber-based curable composition is cured, that is, the vinyl group of the vinyl group-containing organopolysiloxane (A) and the hydride group of the organohydrogenpolysiloxane (B) undergo a hydrosilylation reaction. When a network (crosslinked structure) is formed by these, the vinyl group of the silica particles (C) also participates in the hydrosilylation reaction with the hydride group of the organohydrogenpolysiloxane (B). The silica particles (C) are also taken in. As a result, the hardness and the modulus of the formed silicone rubber can be reduced.

  As the silane coupling agent (D), a silane coupling agent having a hydrophobic group and a silane coupling agent having a vinyl group can be used in combination.

  Examples of the silane coupling agent (D) include those represented by the following formula (4).

Y _n -Si- (X) _4-n (4)
In the above formula (4), n represents an integer of 1 to 3. Y represents a functional group of any of those having a hydrophobic group, a hydrophilic group or a vinyl group. When n is 1, it is a hydrophobic group, and when n is 2 or 3, at least one of them is It is a hydrophobic group. X represents a hydrolyzable group.

  The hydrophobic group is an alkyl group having 1 to 6 carbon atoms, an aryl group, or a hydrocarbon group obtained by combining these, and examples thereof include a methyl group, an ethyl group, a propyl group, and a phenyl group. A methyl group is preferred.

  Examples of the hydrophilic group include a hydroxyl group, a sulfonic acid group, a carboxyl group, and a carbonyl group. Among them, a hydroxyl group is particularly preferable. The hydrophilic group may be contained as a functional group, but is preferably not contained from the viewpoint of imparting hydrophobicity to the silane coupling agent (D).

Furthermore, examples of the hydrolyzable group include an alkoxy group such as a methoxy group and an ethoxy group, a chloro group and a silazane group. Among them, a silazane group is preferable because of high reactivity with the silica particles (C). Incidentally, those having a silazane group as hydrolyzable groups, the characteristics of its structure the formula (4) in the structure of (Y _n -Si-) comes to have two.

  Specific examples of the silane coupling agent (D) represented by the above formula (4) include, for example, those having a hydrophobic group as a functional group, such as methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, and methyltrimethoxysilane. Alkoxysilanes such as ethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane; methyltrichlorosilane Chlorosilanes such as dimethyldichlorosilane, trimethylchlorosilane and phenyltrichlorosilane; hexamethyldisilazane; and those having a vinyl group as a functional group include methacryloxypropyltriethoxysilane. Alkoxysilanes such as methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane and vinylmethyldimethoxysilane; vinyltrichlorosilane, vinylmethyl Chlorosilanes such as dichlorosilane; and divinyltetramethyldisilazane. Among them, considering the above description, in particular, those having a hydrophobic group are hexamethyldisilazane, and those having a vinyl group are divinyltetramethyl. Preferably it is disilazane.

In the present embodiment, the lower limit of the content of the silane coupling agent (D) is preferably 1% by mass or more based on 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A). It is more preferably at least 5 mass%, more preferably at least 5 mass%. The upper limit of the content of the silane coupling agent (D) is preferably 100% by mass or less, and more preferably 80% by mass or less, based on 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A). More preferably, it is still more preferably 40% by mass or less.
By setting the content of the silane coupling agent (D) to the above lower limit or more, the conductive resin film formed by using the conductive paste has a proper adhesion to the substrate, and the silica particles (C In the case of using ()), it is possible to contribute to improvement of the mechanical strength of the wiring and the substrate as a whole. By setting the content of the silane coupling agent (D) to the upper limit or less, the conductive resin film can have appropriate mechanical properties.

<< Platinum or platinum compound (E) >>
The silicone rubber-based curable composition of the present embodiment can contain platinum or a platinum compound (E).
Platinum or a platinum compound (E) is a catalyst component that acts as a catalyst during curing. The amount of platinum or platinum compound (E) added is a catalytic amount.

  As the platinum or platinum compound (E), known compounds can be used, for example, platinum black, platinum-supported silica or carbon black, chloroplatinic acid or an alcohol solution of chloroplatinic acid, chloride or the like. Complex salts of platinic acid with olefins and complex salts of chloroplatinic acid with vinyl siloxane are exemplified.

  In addition, platinum or a platinum compound (E) may be used alone or in combination of two or more.

In the present embodiment, the content of platinum or the platinum compound (E) in the silicone rubber-based curable composition is, specifically, the vinyl group-containing organopolysiloxane (A), the silica particles (C), The amount of the platinum group metal is 0.01 to 1000 ppm by weight, preferably 0.1 to 500 ppm, based on 100 parts by weight of the total amount of the silane coupling agent (D).
By setting the content of platinum or the platinum compound (E) to the above lower limit or more, the conductive paste can be cured at an appropriate speed. Further, when the content of platinum or the platinum compound (E) is equal to or less than the above upper limit, it is possible to contribute to a reduction in cost when producing a conductive paste.

  The catalyst platinum or platinum compound (E) may use another catalyst or may be used in combination with platinum or the platinum compound (E). As another catalyst, for example, an organic peroxide is used. Known organic peroxides can be used, for example, ketone peroxides, diacyl peroxides, hydroperoxides, dialkyl peroxides, peroxyketals, alkyl peresters, One or more selected from the group consisting of oxyesters and peroxydicarbonates can be included.

<< water (F) >>
Further, the silicone rubber-based curable composition of the present embodiment may contain water (F) in addition to the above components (A) to (E).

  Water (F) is a component that functions as a dispersion medium for dispersing the components contained in the silicone rubber-based curable composition and that contributes to the reaction between the silica particles (C) and the silane coupling agent (D). . Therefore, in the silicone rubber, the silica particles (C) and the silane coupling agent (D) can be more reliably connected to each other, and uniform characteristics can be exhibited as a whole.

  Further, when water (F) is contained, the content thereof can be appropriately set, and specifically, for example, 10 to 100 parts by weight with respect to 100 parts by weight of the silane coupling agent (D). And more preferably 30 to 70 parts by weight. This allows the reaction between the silane coupling agent (D) and the silica particles (C) to proceed more reliably.

(Other components)
Further, the silicone rubber-based curable composition of the present embodiment may further contain other components in addition to the above components (A) to (F). As other components, for example, silica particles other than silica particles (C) such as diatomaceous earth, iron oxide, zinc oxide, titanium oxide, barium oxide, magnesium oxide, cerium oxide, calcium carbonate, magnesium carbonate, zinc carbonate, glass wool, and mica And additives such as inorganic fillers, reaction inhibitors, dispersants, pigments, dyes, antistatic agents, antioxidants, flame retardants, and thermal conductivity improvers.

(Conductive filler)
The conductive paste of the present embodiment can include a conductive filler. As the conductive filler, a known conductive material may be used, but it may include scaly metal powder (G). These may be used alone or in combination of two or more.

The average particle diameter _{D 50} of the scale-like metal powder (G), for example, less than 2.30 14.0, more preferably not more than 10.0μm least 2.30, more preferably It is 3.00 μm or more and 9.40 μm or less.
By appropriately selecting the average particle diameter D ₅₀ and the like of the scaly metal powder (G), can control the aspect A1, A1 in the wiring.
The average particle diameter D ₅₀ of the metal powder (G) is 50% particle diameter measured by a laser diffraction particle size measuring apparatus. It is the particle size at the point where 50% by mass is accumulated from the smaller particle size in the volume-based particle size distribution.

  The metal powder (G) may contain anything other than the scaly metal powder (G). The shape of the other metal powder (G) is not limited, but a conventionally used one such as a dendritic or spherical shape can be used.

The metal constituting the metal powder (G) is not particularly limited, but may be, for example, at least one of copper, silver, gold, nickel, tin, lead, zinc, bismuth, antimony, and metal powder obtained by alloying them. Alternatively, two or more of these can be included.
Among these, the metal powder (G) preferably contains silver or copper, that is, contains silver powder or copper powder, from the viewpoint of high conductivity and high availability.
The metal powder (G) may be coated with another metal.

  In the present embodiment, the lower limit of the content of the conductive filler in the conductive paste is preferably 30% by mass or more, more preferably 40% by mass or more, based on the entire conductive paste. , 50% by mass or more. Further, the upper limit of the content of the conductive filler in the conductive paste is, for example, preferably 90% by mass or less, 85% by mass or less, and more preferably 75% by mass or less based on the whole of the conductive paste. It is more preferable that the content be 65% by mass or less.

  Further, the lower limit of the content of the conductive filler in the wiring containing the elastomer and the conductive filler is preferably 30% by mass or more, more preferably 40% by mass or more based on the whole wiring. , 50% by mass or more. The upper limit of the conductive filler content in the wiring is, for example, preferably 95% by mass or less, 90% by mass or less, and more preferably 87% by mass or less, based on the entire wiring. , 85% by mass or less.

  By setting the content of the conductive filler to be equal to or more than the lower limit, the wiring containing the elastomer and the conductive filler can have appropriate conductive properties. Further, by setting the content of the conductive filler to be equal to or less than the upper limit, the wiring can have appropriate flexibility.

  The content of the scaly metal powder (G) is, for example, 90% by mass or more, preferably 95% by mass or more, and more preferably 99% by mass or more based on 100% by mass of the conductive filler. On the other hand, it may be 100% by mass or less.

  The lower limit of the content of the silica particles (C) in the wiring containing the elastomer and the conductive filler is, for example, 1% by mass with respect to 100% by mass of the total amount of the silica particles (C) and the conductive filler. Or more, preferably 3% by mass or more, and more preferably 5% by mass or more. Thereby, the mechanical strength of the wiring can be improved. On the other hand, the upper limit of the content of the silica particles (C) in the wiring is, for example, 20% by mass or less, preferably 15% by mass, based on the total amount of 100% by mass of the silica particles (C) and the conductive filler. %, More preferably 10% by mass or less. As a result, the balance between the electrical characteristics of the wiring and the mechanical strength can be achieved.

(solvent)
The conductive paste of the present embodiment contains a solvent. As the solvent, various known solvents can be used, and for example, a high boiling point solvent can be included. These may be used alone or in combination of two or more.

  The lower limit of the boiling point of the high boiling solvent is, for example, 100 ° C. or higher, preferably 130 ° C. or higher, and more preferably 150 ° C. or higher. Thereby, printing stability such as screen printing can be improved. On the other hand, the upper limit of the boiling point of the high boiling point solvent is not particularly limited, but may be, for example, 300 ° C or lower, 290 ° C or lower, or 280 ° C or lower. Accordingly, an excessive heat history at the time of forming the wiring can be suppressed, so that the damage to the underlying substrate and the shape of the wiring formed of the conductive paste can be favorably maintained.

  The solvent of the present embodiment can be appropriately selected from the viewpoint of solubility and boiling point of the elastomer composition. For example, an aliphatic hydrocarbon having 5 to 20 carbon atoms, preferably 8 to 18 carbon atoms is preferable. It may contain an aliphatic hydrocarbon, more preferably an aliphatic hydrocarbon having 10 to 15 carbon atoms.

Examples of the solvent of the present embodiment include, for example, aliphatic hydrocarbons such as pentane, hexane, cyclohexane, heptane, methylcyclohexane, ethylcyclohexane, octane, decane, dodecane, and tetradecane; benzene, toluene, ethylbenzene, xylene , Trifluoromethylbenzene, aromatic hydrocarbons such as benzotrifluoride; diethyl ether, diisopropyl ether, dibutyl ether, cyclopentyl methyl ether, cyclopentyl ethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, 1,4- Ethers such as dioxane, 1,3-dioxane and tetrahydrofuran; dichloromethane, chloroform, 1,1-dic Haloalkanes such as loethane, 1,2-dichloroethane, 1,1,1-trichloroethane, and 1,1,2-trichloroethane; carboxylic acid amides such as N, N-dimethylformamide and N, N-dimethylacetamide; dimethyl sulfoxide And sulfoxides such as diethylsulfoxide. These may be used alone or in combination of two or more.
The solvent used here may be appropriately selected from solvents capable of uniformly dissolving or dispersing the components in the conductive paste.

  The lower limit of the viscosity of the conductive paste measured at room temperature 25 ° C. at a shear rate of 20 [1 / s] is, for example, 1 Pa · s or more, preferably 5 Pa · s or more, and more preferably 10 Pa · s or more. s or more. Thereby, the film forming property can be improved. Further, shape retention can be improved even when a thick film is formed. On the other hand, the upper limit of the viscosity of the conductive paste at room temperature of 25 ° C. is, for example, 100 Pa · s or less, preferably 90 Pa · s or less, and more preferably 80 Pa · s or less. Thereby, the printability of the conductive paste can be improved.

(Method of manufacturing conductive paste)
Hereinafter, a method for producing the conductive paste according to the present embodiment will be described.

  The conductive paste of the present embodiment can be manufactured, for example, through the following steps.

  First, the respective components of the silicone rubber-based curable composition are uniformly mixed by an arbitrary kneading apparatus to prepare a silicone rubber-based curable composition.

[1] For example, a predetermined amount of a vinyl group-containing organopolysiloxane (A), silica particles (C), and a silane coupling agent (D) are weighed, and then kneaded by an arbitrary kneading device. A kneaded material containing these components (A), (C) and (D) is obtained.

  The kneaded product is preferably obtained by previously kneading the vinyl group-containing organopolysiloxane (A) and the silane coupling agent (D), and then kneading (mixing) the silica particles (C). Thereby, the dispersibility of the silica particles (C) in the vinyl group-containing organopolysiloxane (A) is further improved.

  When obtaining this kneaded product, water (F) may be added to the kneaded product of each of the components (A), (C), and (D) as necessary. This allows the reaction between the silane coupling agent (D) and the silica particles (C) to proceed more reliably.

  Further, it is preferable that the kneading of the components (A), (C) and (D) is performed through a first step of heating at a first temperature and a second step of heating at a second temperature. Thus, in the first step, the surface of the silica particles (C) can be surface-treated with the coupling agent (D), and in the second step, the surface of the silica particles (C) and the coupling agent (D) can be treated. By-products generated by the reaction can be reliably removed from the kneaded material. Thereafter, if necessary, the component (A) may be added to the obtained kneaded material, and further kneaded. Thereby, the familiarity of the components of the kneaded material can be improved.

  The first temperature is preferably, for example, about 40 to 120 ° C, and more preferably, for example, about 60 to 90 ° C. The second temperature is preferably, for example, about 130 to 210 ° C, and more preferably, for example, about 160 to 180 ° C.

  The atmosphere in the first step is preferably an inert atmosphere such as a nitrogen atmosphere, and the atmosphere in the second step is preferably a reduced-pressure atmosphere.

  Further, the time of the first step is, for example, preferably about 0.3 to 1.5 hours, and more preferably about 0.5 to 1.2 hours. The time of the second step is, for example, preferably about 0.7 to 3.0 hours, and more preferably about 1.0 to 2.0 hours.

  By setting the first step and the second step under the above conditions, the above-mentioned effect can be more remarkably obtained.

[2] Next, a predetermined amount of the organohydrogenpolysiloxane (B) and platinum or platinum compound (E) are weighed, and then, using an arbitrary kneading apparatus, the kneaded material prepared in the above step [1]. Then, the respective components (B) and (E) are kneaded to obtain a silicone rubber-based curable composition (elastomer composition).

  When kneading the components (B) and (E), the kneaded product previously prepared in the above step [1] and the organohydrogenpolysiloxane (B) were prepared in the above step [1]. It is preferable to knead the kneaded material with platinum or the platinum compound (E), and then knead the respective kneaded materials. Thereby, each component (A) to (E) can be surely contained in the silicone rubber-based curable composition without advancing the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B). Can be dispersed.

  The temperature at which the components (B) and (E) are kneaded is, for example, preferably about 10 to 70 ° C., and more preferably about 25 to 30 ° C., as the roll set temperature.

  Further, the kneading time is preferably, for example, about 5 minutes to 1 hour, and more preferably about 10 to 40 minutes.

  In step [1] and step [2], by setting the temperature within the above range, the progress of the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B) can be more accurately performed. Can be prevented or suppressed. Further, in the step [1] and the step [2], by setting the kneading time within the above range, the components (A) to (E) can be more reliably dispersed in the silicone rubber-based curable composition. Can be.

  The kneading device used in each of the steps [1] and [2] is not particularly limited, and for example, a kneader, a two-roll, a Banbury mixer (continuous kneader), a pressure kneader, and the like can be used.

  In the step [2], a reaction inhibitor such as 1-ethynylcyclohexanol may be added to the kneaded material. Thereby, even if the temperature of the kneaded material is set to a relatively high temperature, the progress of the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B) is more accurately prevented or suppressed. be able to.

  In the step [2], the organohydrogenpolysiloxane (B) is replaced with platinum or a platinum compound (E), or is used in combination with the organohydrogenpolysiloxane (B) and platinum or a platinum compound (E). Other catalysts such as organic peroxides may be added. Preferred conditions such as temperature and time for kneading the other catalyst and the equipment to be used may be the same as the conditions for kneading the organohydrogenpolysiloxane (B) and platinum or the platinum compound (E). .

  [3] Next, the elastomer composition (silicone rubber-based curable composition) obtained in the step [2] is dissolved in a solvent, and a metal powder (G) is added thereto. Can be obtained.

[Use]
Hereinafter, an example of the use of the conductive paste of the present embodiment will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view of an electronic device 100 including such wirings.

  The electronic device 100 can include a wiring board 50 and an electronic component 60 as shown in FIG. The wiring substrate 50 is configured by providing the wiring 10 on the substrate 20. As the substrate 20, an insulating substrate having elasticity can be used. On the other hand, the wiring 10 can be made of the conductive paste of the present embodiment. The electronic component 60 may be configured to be electrically connected to the wiring 10 constituting such an elastic wiring substrate (wiring substrate 50).

  Since the conductive paste of the present embodiment can maintain the electrical properties of the cured product obtained by repeatedly expanding and contracting while increasing the mechanical strength of the obtained cured product, the electronic paste having excellent connection reliability and durability can be obtained. The structure of the device 100 can be realized.

  The electronic device 100 of the present embodiment is used, for example, as a wearable device, and can be suitably used for a device that repeatedly expands and contracts in each direction. This wearable device can be used as a wearable device that can be worn on a body or clothing.

Further, the substrate 20 constituting the electronic device 100 of the present embodiment is usually made of a flexible material.
As this material, the same material as the above-mentioned elastomer can be adopted. Specifically, silicone rubber, urethane rubber, fluorine rubber, nitrile rubber, acrylic rubber, styrene rubber, chloroprene rubber, ethylene propylene rubber, or the like can be used, and this material can be appropriately selected according to the application and the like. . Further, the substrate 20 may be made of a cured product of the above-mentioned silicone rubber-based curable composition.

  Further, the substrate 20 can be manufactured using the above-described elastomer composition. In addition, the substrate 20 may be configured using an insulating paste containing an elastomer composition containing silica particles and a solvent. As the solvent, the above-mentioned solvent species similar to the above-described solvents can be used, and among them, a solvent having solubility in the conductive paste, which is a cured product of the conductive paste or the conductive paste, is used. be able to. As a specific solvent for the insulating paste, for example, a high-boiling solvent or the like can be used.

  Further, the electronic component 60 may be appropriately selected from known components according to the application. Specifically, a semiconductor element and a resistor or a capacitor other than the semiconductor element can be used. Examples of the semiconductor element include a transistor, a diode, an LED, and a capacitor. In the electronic device 100 of the present embodiment, the electronic component 60 is electrically connected by the wiring 10.

Further, the electronic device 100 of the present embodiment may be provided with a cover member 30 as necessary. The provision of the cover member 30 can prevent the wiring 10 and the electronic component 60 from being damaged. The cover member 30 may be configured to cover the electronic component 60 and the wiring 10 on the substrate 20.
The cover member 30 can be made of the same material as the substrate 20. Since such a cover member 30 follows expansion and contraction of the substrate 20 and the wiring 10, the electronic device 100 can expand and contract without bias, and can contribute to a longer life of the electronic device 100.

Next, an example of a manufacturing process of the electronic device 100 of the present embodiment will be described with reference to FIG.
FIG. 2 is a cross-sectional view schematically illustrating a manufacturing process of the electronic device 100 according to the present embodiment.

  First, as shown in FIG. 2A, a support 120 is placed on a work table 110, and an insulating paste 130 is applied on the support 120. As the coating method, various methods can be used. For example, a printing method such as a squeegee method using a squeegee 140 can be used. Subsequently, the insulating paste 130 in the form of a coating film is dried to form an insulating layer 132 (a dried insulating sheet) on the support 120. The drying conditions can be appropriately set according to the type and amount of the solvent in the insulating paste 130. For example, the drying temperature is set to 150 ° C. to 180 ° C., and the drying time is set to 1 minute to 30 minutes. it can.

  Subsequently, as shown in FIG. 2B, a mask 160 having a predetermined opening pattern is disposed on the insulating layer 132. Then, as shown in FIGS. 2B and 2C, a conductive paste 150 is applied on the insulating layer 132 via the mask 160. As a coating method, a method similar to the method of applying the insulating paste 130 can be used. For example, squeegee printing using the squeegee 140 may be used. Here, when the insulating paste 130 and the conductive paste 150 each include a thermosetting elastomer composition, a conductive coating film (conductive layer 152) having a predetermined pattern shape is laminated on the dried insulating layer 132. Thereafter, these may be collectively cured. The curing treatment can be appropriately set according to the thermosetting elastomer composition. For example, the curing temperature can be 160 ° C. to 220 ° C., and the curing time can be 1 hour to 3 hours. After the curing process or before the curing process, the mask 160 can be removed as shown in FIG. Thus, a wiring which is a cured product of the conductive layer 152 and has a predetermined pattern shape can be formed on the substrate formed of the cured product of the insulating layer 132.

Subsequently, as shown in FIG. 2E, an insulating paste 170 is further applied on the insulating layer 132 and the patterned conductive layer 152, and the insulating layer 172 is formed as shown in FIG. Can be formed. These steps may be repeated as appropriate. In addition, the support 120 can be separated from the insulating layer 132.
As described above, the electronic device 100 shown in FIG. 2F can be obtained.

  When an insulating sheet is used instead of the insulating paste, the process may be started from the step shown in FIG. That is, an insulating sheet may be provided on the support 120, and after predetermined drying, the conductive paste 150 may be applied to the insulating sheet via the mask 160. Subsequent steps can be performed according to the above-described steps. Thus, the electronic device 100 shown in FIG. 2F can be obtained.

  It should be noted that the present invention is not limited to the above-described embodiment, but includes modifications and improvements as long as the object of the present invention can be achieved.

  Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

  The materials used in the examples and comparative examples are as follows.

(Vinyl group-containing organopolysiloxane (A))
(A1-1): first vinyl group-containing linear organopolysiloxane: vinyl group content: 0.13 mol%, Mn = 227,734, Mw = 573,903, IV value (dl / g) = 0.89), a vinyl group-containing dimethylpolysiloxane synthesized according to the following synthesis scheme 1 (the structure represented by the above formula (1-1))
(A1-2): a second vinyl group-containing linear organopolysiloxane: the vinyl group content is 0.92 mol%, and the vinyl group-containing dimethylpolysiloxane synthesized by the following synthesis scheme 2 (the above formula (1- A structure represented by 1) wherein R ¹ and R ² are vinyl groups)

(Organohydrogenpolysiloxane (B))
(B-1): Organohydrogenpolysiloxane: "TC-25D" manufactured by Momentive, Inc.
(B-2): Organohydrogenpolysiloxane: "88466" manufactured by Momentive

(Silica particles (C))
(C): silica fine particles (particle diameter 7 nm, specific surface area 300 m ² / g), manufactured by Nippon Aerosil Co., Ltd., “AEROSIL300”

(Silane coupling agent (D))
(D-1): Hexamethyldisilazane (HMDZ), manufactured by Gelest, “HEXAMETHYLDISILAZANE (SIH6110.1)”
(D-2) Divinyltetramethyldisilazane, manufactured by Gelest, "1,3-DIVINYLTETRAMETHYLDISILAZANE (SID4612.0)"

(Platinum or platinum compound (E))
(E-1): Platinum compound (Momentive, trade name "TC-25A")
(E-2): Platinum compound, PLATINUM DIVINYL TETRAMETHYLDISILOXANE COMPLEX (in xylene) (manufactured by Gelest, trade name "SIP6831.2")

(Water (F))
(F): pure water

(Additive)
(Reaction inhibitor 1): 1-ethynyl-1-cyclohexanol (manufactured by Tokyo Chemical Industry Co., Ltd.)

(Metal powder (G))
Table 1 shows the metal powders G1 to G3 used in each example and each comparative example.

The average particle diameter D ₅₀ , specific surface area, and tap density in Table 1 were measured as follows.
The average particle diameter _{D 50} of the metal powder (G) is a laser diffraction particle size measuring apparatus (manufactured by Shimadzu Corporation, SALD-3000 J) was 50% particle size measured by. It is the particle size at the point where 50% by mass is accumulated from the smaller particle size in the volume-based particle size distribution.
The specific surface area of the metal powder (G) was a BET specific surface area measured using an automatic specific surface area measuring device (manufactured by Shimadzu Corporation, product name: Flowsorb 2300 type).
The tap density of the metal powder (G) was measured according to JIS Z2012-2012 "Metal powder-method of measuring tap density".

(Synthesis of vinyl group-containing organopolysiloxane (A))
[Synthesis Scheme 1: Synthesis of First Vinyl Group-Containing Linear Organopolysiloxane (A1-1)]
According to the following formula (5), a first vinyl group-containing linear organopolysiloxane (A1-1) was synthesized.
That is, 74.7 g (252 mmol) of octamethylcyclotetrasiloxane and 0.1 g of potassium siliconate were placed in a 300 mL separable flask having a cooling tube and a stirring blade, which had been purged with Ar gas, heated, and heated at 120 ° C. for 30 minutes. Stirred. At this time, an increase in viscosity was confirmed.
Thereafter, the temperature was raised to 155 ° C., and stirring was continued for 3 hours. After 3 hours, 0.1 g (0.6 mmol) of 1,3-divinyltetramethyldisiloxane was added, and the mixture was further stirred at 155 ° C for 4 hours.
Further, after 4 hours, the mixture was diluted with 250 mL of toluene and then washed three times with water. The washed organic layer was washed several times with 1.5 L of methanol to perform reprecipitation purification, thereby separating an oligomer and a polymer. The obtained polymer was dried under reduced pressure at 60 ° C. overnight to obtain a first linear organopolysiloxane containing vinyl group (A1-1) (Mw = 573,903, Mn = 227,734). The vinyl group content calculated by H-NMR spectrum measurement was 0.13 mol%.

[Synthesis Scheme 2: Synthesis of Second Vinyl Group-Containing Linear Organopolysiloxane (A1-2)]
In the synthesis step of (A1-1), 2,4,6,8-tetramethyl 2,4,6,8-tetravinylcyclotetrasiloxane was added in addition to 74.7 g (252 mmol) of octamethylcyclotetrasiloxane. Except that 86 g (2.5 mmol) was used, the same procedure as in the synthesis step of (A1-1) was carried out to obtain the second vinyl group-containing linear organopolysiloxane ( A1-2) was synthesized. The vinyl group content calculated by H-NMR spectrum measurement was 0.92 mol%.

(Preparation of Silicone Rubber Curable Composition 1 for Conductive Paste)
The silicone rubber-based curable composition 1 was prepared as follows. First, a mixture of 90% of a vinyl group-containing organopolysiloxane (A), a silane coupling agent (D) and water (F) is kneaded in advance at a rate shown in Table 2 below, and then the mixture is mixed with silica particles ( C) was further added and kneaded to obtain a kneaded product (silicone rubber compound).
Here, the kneading after the addition of the silica particles (C) includes a first step of kneading under a nitrogen atmosphere at 60 to 90 ° C. for one hour for a coupling reaction, and a step of removing by-products (ammonia). And a second step of kneading under reduced pressure atmosphere at 160 to 180 ° C. for 2 hours. Thereafter, the mixture is cooled and the remaining 10% of vinyl group-containing organopolysiloxane (A) is added twice. It was added separately and kneaded for 20 minutes.
Subsequently, organohydrogenpolysiloxane (B), platinum or platinum compound (E), and reaction inhibitor 1 were added to 100 parts by weight of the obtained kneaded product (silicone rubber compound) at the ratios shown in Table 2 below. Then, the mixture was kneaded with a roll to obtain a silicone rubber-based curable composition 1 (elastomer composition 1).

(Preparation of Silicone Rubber Curable Composition 2 for Substrate)
The silicone rubber-based curable composition 2 was prepared as follows. First, a mixture of 90% of a vinyl group-containing organopolysiloxane (A), a silane coupling agent (D) and water (F) is kneaded in advance at a rate shown in Table 2 below, and then the mixture is mixed with silica particles ( C) was further added and kneaded to obtain a kneaded product (silicone rubber compound).
Here, the kneading after the addition of the silica particles (C) includes a first step of kneading under a nitrogen atmosphere at 60 to 90 ° C. for one hour for a coupling reaction, and a step of removing by-products (ammonia). And a second step of kneading under reduced pressure atmosphere at 160 to 180 ° C. for 2 hours. Thereafter, the mixture is cooled and the remaining 10% of vinyl group-containing organopolysiloxane (A) is added twice. It was added separately and kneaded for 20 minutes.
Subsequently, organohydrogenpolysiloxane (B), platinum or a platinum compound (E) was added to 100 parts by weight of the obtained kneaded product (silicone rubber compound) at a ratio shown in Table 2 below, and kneaded with a roll. Thus, a silicone rubber-based curable composition 2 (elastomer composition 2) was obtained.

<Example 1: conductive paste 1>
The obtained 13.7 parts by weight of the silicone rubber-based curable composition 1 (elastomer composition 1) was immersed in 31.8 parts by weight of tetradecane (solvent), followed by stirring with a rotation / revolution mixer. A liquid conductive paste 1 was obtained by adding 0.5 parts by weight of the metal powder (G1) shown in Table 1 and kneading with a three-roll mill.

<Example 2: conductive paste 2>
The obtained 13.7 parts by weight of the silicone rubber-based curable composition 1 (elastomer composition 1) was immersed in 31.8 parts by weight of tetradecane (solvent), followed by stirring with a rotation / revolution mixer. A liquid conductive paste 2 was obtained by adding 0.5 parts by weight of the metal powder (G2) described in Table 1 and kneading with a three-roll mill.

<Comparative example 1: conductive paste 2>
The obtained 13.7 parts by weight of the silicone rubber-based curable composition 1 (elastomer composition 1) was immersed in 31.8 parts by weight of tetradecane (solvent), followed by stirring with a rotation / revolution mixer. A liquid conductive paste 3 was obtained by adding 0.5 parts by weight of the metal powder (G3) described in Table 1 and kneading with a three-roll mill.

[Preparation of stretchable wiring board]
The obtained silicone rubber-based curable composition 2 (elastomer composition 2) was pressed at 170 ° C. and 10 MPa for 10 minutes to form a sheet having a thickness shown in Table 2 and first cured. Subsequently, secondary curing was performed at 200 ° C. for 4 hours to obtain a sheet-like silicone rubber (a cured product of a silicone rubber-based curable composition). It was cut out into a width: 2 cm × length: 5 cm to produce a “substrate”.
Subsequently, using the conductive pastes 1 to 3 obtained in the respective Examples and Comparative Examples, a wiring pattern was drawn on the obtained “substrate”, and this was cured at 170 ° C. for 120 minutes. Stretchable wiring substrates 1 to 3 (test pieces) having a “wiring pattern” of 500 μm in width × 50 μm in height × 30 mm in length were produced.

[Evaluation of stretchable wiring board]
The obtained stretchable wiring boards 1 to 3 were evaluated according to the following evaluation items. Table 3 shows the evaluation results.

(Aspect measurement)
Hereinafter, the procedure of measuring the aspect of the conductive filler in the wiring of the obtained stretchable wiring board is as follows (1) to (3). The measurement procedure will be described using a perspective view (FIG. 3) showing an outline of the stretchable wiring board. In FIG. 3, the wiring board 50 corresponds to the above-mentioned elastic wiring board (test piece), the wiring 10 corresponds to the above “wiring pattern”, and the board 20 corresponds to the above “substrate”.

(1) The wiring 10 is cut in the thickness direction (Z direction) along the width direction (X direction) of the wiring 10 so as to pass through a central portion in the longitudinal direction (Y direction) of the wiring 10 to obtain a cut surface. Was. The obtained cut surface was polished using an ion beam (cross section polisher, manufactured by JEOL Ltd., SM-09010) under a reduced-pressure argon gas atmosphere to obtain a cross section a1. The cross section a1 represents a cross section taken along the line a1-a1 in FIG.
(2) Using an ion beam (cross section polisher, manufactured by JEOL Ltd., SM-09010), the surface 12 of the wiring 10 is placed in a depth direction (a direction opposite to the Z direction) under a reduced pressure argon gas atmosphere. A predetermined depth of 005 mm to 0.02 mm was polished to obtain a cross section a2. The cross section a2 represents a cross section taken along the line a2-a2 in FIG. As a polishing condition of the cross section polisher, a voltage amount: 5.0 kV and a time: 8 hours were used.
(3) Subsequently, for each of the cross section a1 obtained in (1) and the cross section a2 obtained in (2), a scanning electron microscope (SEM) under the conditions of a visual field area: 128 μm × 102 μm and a magnification: 1000 × ) Was used to obtain an observation image. FIG. 4 shows the SEM image of the cross section a1 in Example 1, FIG. 5 shows the SEM image of the cross section a2 in FIG. 6, FIG. 6 shows the SEM image of the cross section a1 in Example 2, FIG. 8 is shown in FIG. 8, and the SEM image of section a2 is shown in FIG.
For the obtained observation image, when taking a histogram with the gradation versus the number of pixels, image analysis is performed based on the binarized image at the gradation that is the valley of the two peaks, and the conductive filler The aspect of the orthogonal projection was measured, and the average value of the 30 measured values was determined as the average aspect.
The average aspect calculated from the cross section a1 was A1, and the average aspect calculated from the cross section a2 was A2. “A1 / A2” was calculated based on A1 and A2. Table 3 shows the evaluation results.

(Measurement of resistance value)
Using a DC voltage / current source / monitor (6241A) manufactured by ADC Corporation, the obtained test piece was stretched by 20% in the length direction for 3 seconds while measuring the resistance, and held for 10 seconds. The change in the resistance value (Ω) was constantly monitored, and the change during the test was analyzed. The initial resistance value before 20% elongation and the resistance value at 20% elongation were measured for three samples, and the average value of the three values was used as the measured value. Table 3 shows the evaluation results.

  The stretchable wiring boards of Example 1 and Example 2 have a smaller initial resistance value when not stretched and a smaller resistance value when stretched as compared with Comparative Example 1, so that they have excellent conductivity when the board is stretched. It has been found that the substrate structure can be realized. Such a stretchable wiring board is expected to be suitably used for a wearable device.

DESCRIPTION OF SYMBOLS 10 Wiring 12 Surface 20 Substrate 30 Cover material 50 Wiring board 60 Electronic component 100 Electronic device 110 Workbench 120 Supporter 130 Insulating paste 132 Insulating layer 140 Squeegee 150 Conductive paste 152 Conductive layer 160 Mask 170 Insulating paste 172 Insulating layer

According to the present invention,
A substrate containing an elastomer;
A stretchable wiring board, which is laminated on one surface of the substrate and has a wiring containing an elastomer , a conductive filler , and silica particles (C) .
The conductive filler contains scaly metal powder (G),
The content of the conductive filler in the wiring is 50% by mass or more and 90% by mass or less;
The content of the silica particles (C) in the wiring is 1% by mass or more and 10% by mass or less based on 100% by mass of the total amount of the silica particles (C) and the conductive filler;
The average aspect of the conductive filler in the cross section a1 when the wiring is cut in the thickness direction along the width direction, which is obtained based on the following procedures (1) to (3), is A1, and the wiring is in the thickness direction. Assuming that the average aspect of the conductive filler in the cross section a2 when cut in a direction perpendicular to the above is A2, A1 and A2 satisfy the following formula (I).
1.1 ≦ A1 / A2 Formula (I)
(procedure)
(1) A cross section obtained by cutting the wiring in the thickness direction along the width direction of the wiring is polished using an ion beam to obtain a cross section a1.
(2) The surface of the wiring is polished in the depth direction by 0.005 mm to 0.02 mm using an ion beam to obtain a cross section a2.
(3) Observation images are obtained using a scanning electron microscope (SEM) under the conditions of a visual field area of 128 μm × 102 μm and a magnification of 1000 times for each of the obtained cross sections a1 and a2. When taking a histogram of the obtained observation image by gradation versus pixel number, image analysis is performed based on the binarized image at the gradation that is the valley of two peaks, and the conductive filler The aspect of the orthogonal projection is measured, and the average value of the 30 measured values is calculated as the average aspect. The average aspect calculated from the cross section a1 is A1, and the average aspect calculated from the cross section a2 is A2.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
Hereinafter, examples of the reference embodiment will be additionally described.
1. A substrate containing an elastomer;
Laminated on one surface of the substrate, and a wiring containing an elastomer and a conductive filler, and a stretchable wiring board having:
The conductive filler contains scaly metal powder (G),
The average aspect of the conductive filler in the cross section a1 when the wiring is cut in the thickness direction along the width direction, which is obtained based on the following procedures (1) to (3), is A1, and the wiring is in the thickness direction. A1 and A2 satisfy the following formula (I), when the average aspect of the conductive filler in the cross section a2 when cut in a direction perpendicular to the elastic wiring board is A2.
1.1 ≦ A1 / A2 Formula (I)
(procedure)
(1) A cross section obtained by cutting the wiring in the thickness direction along the width direction of the wiring is polished using an ion beam to obtain a cross section a1.
(2) The surface of the wiring is polished in the depth direction by 0.005 mm to 0.02 mm using an ion beam to obtain a cross section a2.
(3) Observation images are obtained using a scanning electron microscope (SEM) under the conditions of a visual field area of 128 μm × 102 μm and a magnification of 1000 times for each of the obtained cross sections a1 and a2. When taking a histogram of the obtained observation image by gradation versus pixel number, image analysis is performed based on the binarized image at the gradation that is the valley of two peaks, and the conductive filler The aspect of the orthogonal projection is measured, and the average value of the 30 measured values is calculated as the average aspect. The average aspect calculated from the cross section a1 is A1, and the average aspect calculated from the cross section a2 is A2.
2. 1. The stretchable wiring board according to the above,
An elastic wiring board, wherein the aspect A1 of the conductive filler satisfies the following formula (II).
2.0 ≦ A1 ≦ 10.0 Formula (II)
3. 1. Or 2. The stretchable wiring board according to the above,
An elastic wiring substrate, wherein the elastomer contained in the wiring includes at least one selected from the group consisting of silicone rubber, urethane rubber, fluorine rubber, nitrile rubber, acrylic rubber, styrene rubber, chloroprene rubber, and ethylene propylene rubber.
4. 1. ~ 3. The stretchable wiring board according to any one of the above,
The stretchable wiring board, wherein the metal powder (G) includes at least one selected from the group consisting of copper, silver, gold, nickel, tin, lead, zinc, bismuth, antimony, and alloys thereof.
5. 1. ~ 4. The stretchable wiring board according to any one of the above,
A stretchable wiring board, wherein the content of the conductive filler is 30% by mass or more and 90% by mass or less based on the entire wiring.
6. 1. ~ 5. The stretchable wiring board according to any one of the above,
An elastic wiring substrate, wherein the wiring includes silica particles (C).
7. 6. The stretchable wiring board according to the above,
A stretchable wiring board, wherein the content of the silica particles (C) is 1% by mass or more and 20% by mass or less based on 100% by mass of the total amount of the silica particles (C) and the conductive filler.
8. 1. ~ 7. A wearable device comprising the stretchable wiring substrate according to any one of the above.

<Example 2: conductive paste 2>
The resulting 13.7 parts by weight of the silicone rubber based curable composition 1 (elastomer composition 1) was immersed in 31.8 parts by weight tetradecane (solvent), followed by stirring at planetary centrifugal mixer, 66 A liquid conductive paste 2 was obtained by adding 9.9 parts by weight of the metal powder (G2) shown in Table 1 and kneading with a three-roll mill.

Claims (8)

A substrate containing an elastomer;
Laminated on one surface of the substrate, and a wiring containing an elastomer and a conductive filler, and a stretchable wiring board having:
The conductive filler contains scaly metal powder (G),
The average aspect of the conductive filler in the cross section a1 when the wiring is cut in the thickness direction along the width direction, which is obtained based on the following procedures (1) to (3), is A1, and the wiring is in the thickness direction. A1 and A2 satisfy the following formula (I), when the average aspect of the conductive filler in the cross section a2 when cut in a direction perpendicular to the elastic wiring board is A2.
1.1 ≦ A1 / A2 Formula (I)
(procedure)
(1) A cross section obtained by cutting the wiring in the thickness direction along the width direction of the wiring is polished using an ion beam to obtain a cross section a1.
(2) The surface of the wiring is polished in the depth direction by 0.005 mm to 0.02 mm using an ion beam to obtain a cross section a2.
(3) Observation images are obtained using a scanning electron microscope (SEM) under the conditions of a visual field area of 128 μm × 102 μm and a magnification of 1000 times for each of the obtained cross sections a1 and a2. When taking a histogram of the obtained observation image by gradation versus pixel number, image analysis is performed based on the binarized image at the gradation that is the valley of two peaks, and the conductive filler The aspect of the orthogonal projection is measured, and the average value of the 30 measured values is calculated as the average aspect. The average aspect calculated from the cross section a1 is A1, and the average aspect calculated from the cross section a2 is A2. The stretchable wiring board according to claim 1,
An elastic wiring board, wherein the aspect A1 of the conductive filler satisfies the following formula (II).
2.0 ≦ A1 ≦ 10.0 Formula (II) The stretchable wiring board according to claim 1 or 2,
An elastic wiring substrate, wherein the elastomer contained in the wiring includes at least one selected from the group consisting of silicone rubber, urethane rubber, fluorine rubber, nitrile rubber, acrylic rubber, styrene rubber, chloroprene rubber, and ethylene propylene rubber. It is a stretchable wiring board according to any one of claims 1 to 3,
The stretchable wiring board, wherein the metal powder (G) includes at least one selected from the group consisting of copper, silver, gold, nickel, tin, lead, zinc, bismuth, antimony, and alloys thereof. It is an elastic wiring board according to any one of claims 1 to 4,
A stretchable wiring board, wherein the content of the conductive filler is 30% by mass or more and 90% by mass or less based on the entire wiring. It is an elastic wiring board according to any one of claims 1 to 5,
An elastic wiring substrate, wherein the wiring includes silica particles (C). It is an elastic wiring board according to claim 6,
A stretchable wiring board, wherein the content of the silica particles (C) is 1% by mass or more and 20% by mass or less based on 100% by mass of the total amount of the silica particles (C) and the conductive filler.   A wearable device comprising the stretchable wiring board according to claim 1.