JP2020053619A - Stretchable wiring board and wearable device - Google Patents

Abstract

To provide a stretchable wiring board excellent in characteristics when being stretched and wearable compatibility.SOLUTION: A stretchable wiring board includes: a substrate containing a stretchable wiring board elastomer of the present invention; and wiring placed on one side of the substrate and containing an elastomer and conductive fillers. The stretchable wiring board has a rigid structure in which H1, T1 and T2 satisfy an expression: 20≤H1×(T1/T2)≤1,000 where T1 (μm) represents the thickness of the substrate when being not stretched, H1 represents a type A durometer hardness at 25°C complying with JIS K6253 (1997) of the substrate when being not stretched, and T2 (μm) represents the thickness of the wiring when being not stretched.SELECTED DRAWING: Figure 1

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 an elastic wearable flexible substrate having a wearable housing made of an elastomer and a wiring layer provided on a main surface of the wearable housing.

JP-A-2006-076531

  However, the present inventor has studied and found that the stretchable wiring board described in Patent Document 1 has room for improvement in the characteristics at the time of extension and the suitability for wearable.

  The present inventor further studied and found that the elongation characteristic and the wearable suitability of the stretchable wiring board can be appropriately controlled by using the rigidity parameter represented by the board hardness × (board thickness / wiring thickness) as a guideline. I found it. Further studies based on such findings have revealed that, by setting the rigidity parameter within a predetermined numerical range, it is found that the characteristics of the stretchable wiring board when stretched and the suitability for wearable are improved, and the present invention is completed. Reached.

According to the present invention,
A substrate containing an elastomer;
A stretchable wiring board that is in contact with one surface of the substrate and has a wiring containing an elastomer and a conductive filler,
The thickness of the substrate before unstretching is T1 (μm), the durometer hardness of the substrate at 25 ° C. according to JIS K6253 (1997) is H1 at 25 ° C., and the thickness of the wiring before unstretching is H1. Is T2 (μm),
An elastic wiring board is provided, wherein H1, T1, and T2 have a rigid structure satisfying the following formula (I).
20 ≦ H1 × (T1 / T2) ≦ 1000 (I)

According to the present invention,
A wearable device including the elastic wiring board is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the stretchable wiring board excellent in the characteristic at the time of extension and wearable compatibility, 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 figure for explaining a measuring method of board thickness and wiring thickness.

  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.

The stretchable wiring board according to the present embodiment has a board containing an elastomer and a wiring that is placed on one surface of the board and contains an elastomer and a conductive filler.
The thickness of the substrate when not stretched is T1 (μm),
The type A durometer hardness at 25 ° C. in accordance with JIS K6253 (1997) of the substrate when not stretched is H1,
When the thickness of the unstretched wiring is T2 (μm),
The stretchable wiring board has a rigid structure in which H1, T1, and T2 satisfy the following formula (I).
20 ≦ H1 × (T1 / T2) ≦ 1000 (I)

According to the findings of the present inventor, by appropriately controlling both factors of the substrate hardness and the thickness ratio of the substrate and the wiring, the stress on the wiring during extension is reduced while maintaining the followability to the body. It was found that wiring damage could be suppressed.
As a result of intensive studies based on such knowledge, the characteristics of the stretchable wiring board at the time of elongation can be obtained by combining the two factors and using the rigidity parameter expressed by substrate hardness × (board thickness / wiring thickness) as a guideline. By properly controlling the wearable compatibility and by setting the rigidity parameter within a predetermined numerical range, the elongation characteristic and the wearable compatibility of the stretchable wiring board having the rigid structure defined by the rigidity parameter are improved. Was found.

  Although the detailed mechanism is unknown, the rigid structure specified by the appropriate rigidity parameter reduces the stress on the wiring, suppresses wiring damage and wiring resistance increase after repeated elongation, and follows the body. It is thought that can be raised.

  The stretchable wiring board of the present embodiment can be used for various applications, but can be suitably used for, for example, a wearable device.

  In addition, the stretchable wiring board of the present embodiment suppresses wiring damage after repeated elongation, so that excellent connection reliability, that is, high durability can be realized.

  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 formed 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 has excellent mechanical strength and insulating properties.

(Elastomer)
The elastomer contained in the substrate or the wiring may include 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. . These may be used alone or in combination of two or more.
Among them, the elastomer can include one or more thermosetting elastomers selected from the group consisting of silicone rubber, urethane rubber, and fluoro rubber. Further, the elastomer can contain silicone rubber 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.

  In the present specification, the elastomer composition is used for constituting the elastomer contained in the substrate or the wiring, and is, for example, one or more thermosetting materials selected from the group consisting of silicone rubber, urethane rubber, and fluoro rubber. The composition may include a thermosetting elastomer composition used for forming a conductive elastomer, and preferably may include a silicone rubber-based curable 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. Thereafter, an example in which the substrate is formed using an insulating 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, the weight ratio of (A1-1) :( A1-2) is 50:50 to 95: 5, preferably 60:40 to 92: 8. Preferably it is 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 the present embodiment, the content of the silicone rubber-based curable composition in the conductive paste is preferably 1% by mass or more, more preferably 3% by mass or more based on the whole conductive paste. And more preferably 5% by mass or more. Further, the content of the silicone rubber-based curable composition in the conductive paste is preferably 25% by mass or less, more preferably 20% by mass or less, and more preferably 15% by mass, based on the whole conductive paste. % Is more preferable.
By setting the content of the silicone rubber-based curable composition to the above lower limit or more, the wiring formed using the conductive paste can have appropriate flexibility. Further, by setting the content of the silicone rubber-based curable 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 (C) in addition to the conductive filler to improve the mechanical strength and durability of an elastomer composed of a cured product of the conductive paste or the like. Can be. 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. When the content of the silica particles (C) is equal to or less than the upper limit, the wiring manufactured using the conductive paste can have appropriate conductive characteristics.

<< 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) are as follows.
As those having a hydrophobic group as the functional group, for example, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, Alkoxysilanes such as n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane; chlorosilanes such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane; hexamethyldisilazane Is mentioned. Among them, a silane coupling agent having a trimethylsilyl group containing at least one selected from the group consisting of hexamethyldisilazane, trimethylchlorosilane, trimethylmethoxysilane, and trimethylethoxysilane is preferable.

  As those having a vinyl group as the functional group, for example, methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxy Silane, alkoxysilanes such as vinylmethyldimethoxysilane; chlorosilanes such as vinyltrichlorosilane and vinylmethyldichlorosilane; and divinyltetramethyldisilazane. Among them, methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, divinyltetramethyldisilazane, vinyltriethoxysilane, vinyltrimethoxysilane, and vinyl A silane coupling agent having a vinyl group-containing organosilyl group containing at least one selected from the group consisting of methyldimethoxysilane is preferred.

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 be equal to or more than the lower limit, it has appropriate adhesion between the wiring formed using the conductive paste and the substrate containing the elastomer, and also has silica particles ( When C) is used, 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.

  When the silane coupling agent (D) contains two kinds of a silane coupling agent having a trimethylsilyl group and a silane coupling agent having a vinyl group-containing organosilyl group, hexamethyldisilazane may be used as a compound having a hydrophobic group. As a compound having a vinyl group, it is preferable to include divinyltetramethyldisilazane.

  When the silane coupling agent having a trimethylsilyl group (D1) and the silane coupling agent having a vinyl group-containing organosilyl group (D2) are used in combination, the ratio between (D1) and (D2) is not particularly limited. (D1) :( D2) in a weight ratio of 1: 0.001 to 1: 0.35, preferably 1: 0.01 to 1: 0.20, more preferably 1: 0.03 to 1: 0. .15. By setting such a numerical range, desired physical properties of the silicone rubber can be obtained. Specifically, the balance between the dispersibility of silica in the rubber and the crosslinkability of the rubber can be achieved.

<< 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 means a catalytic amount and can be appropriately set. Specifically, the vinyl group-containing organopolysiloxane (A), the amount of the platinum group metal is 0.01 to 1000 ppm by weight based on 100 parts by weight of the total amount of the silica particles (C) and the silane coupling agent (D). The amount is 1 to 500 ppm.
By setting the content of platinum or the platinum compound (E) to the above lower limit or more, the silicone rubber-based curable composition 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 manufacturing cost.

<< 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.

<< Organic peroxide (H) >>
The silicone rubber-based curable composition of the present embodiment can include an organic peroxide (H). Organic peroxide (H) is a component that acts as a catalyst. The organic peroxide (H) is used in place of the organohydrogenpolysiloxane (B) and the platinum or platinum compound (E), or with the organohydrogenpolysiloxane (B) and the platinum or platinum compound (E) and the organic peroxide. Compound (H) can be used in combination.

  Examples of the organic peroxide (H) include ketone peroxides, diacyl peroxides, hydroperoxides, dialkyl peroxides, peroxyketals, alkyl peresters, peroxyesters, and peroxydioxides. Carbonates; specifically, for example, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, o-methylbenzoyl peroxide, dicumyl peroxide, 2,5-dimethyl- Bis (2,5-t-butylperoxy) hexane, di-t-butylperoxide, t-butylperbenzoate, 1,6-hexanediol-bis-t-butylperoxycarbonate and the like can be mentioned.

  In the present embodiment, the content of the organic peroxide (H) in the silicone rubber-based curable composition is, specifically, a vinyl group-containing organopolysiloxane (A), silica particles (C), and a silane coupling agent. 0.001 to 10% by mass, preferably 0.002 to 8% by mass, based on 100 parts by weight of the total amount of (D). By setting the content of the organic peroxide (H) to the above lower limit or more, the crosslinking reaction can proceed sufficiently, and it is possible to secure physical properties such as high rubber strength and low compression set. Become. Further, by setting the content of the organic peroxide (H) to the above upper limit value or less, it is possible to suppress decomposition products of the catalyst, and also to suppress compression set and suppress discoloration of the obtained sheet. can do.

(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 contains a conductive filler. As the conductive filler, a known conductive material can be used.
For example, the elastomer constituting the wiring can include, for example, metal, carbon, or a conductive polymer as a conductive filler. The conductive filler may be in any of a powder form, a fibrous form, and a wire form. These may be used alone or in combination of two or more.

The conductive filler may include a metal powder (G).
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.

  The shape of the metal powder (G) is not particularly limited, but flakes, dendrites, spheres and the like are used. These may be used alone or in combination of two or more. Among them, it is preferable to use a flaky shape from the viewpoint of connection reliability at the time of expansion and contraction.

  The carbon is not particularly limited as long as it is a known conductive carbon, and examples thereof include carbon black, acetylene black, graphite, carbon fiber, and carbon nanotube.

  As the conductive polymer, a known polymer can be used. For example, a conductive polymer alone, a conductive polymer-coated fiber, or the like can be used.

  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 metal powder (G) is, for example, 90% by mass or more, preferably 95% by mass or more, 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 based on 100% by mass of the total amount of the silica particles (C) and the conductive filler, and is preferably. It is 15% by mass or less, more preferably 10% by mass or less. This makes it possible to achieve a balance between the expansion / contraction electrical characteristics of the wiring and the mechanical strength.

(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.

  Further, in this step [2], instead of the organohydrogenpolysiloxane (B) and the platinum or platinum compound (E), or in combination with the organohydrogenpolysiloxane (B) and the platinum or platinum compound (E) And an organic peroxide (H) may be added. The preferred conditions such as temperature and time for kneading the organic peroxide (G) and the equipment used are the conditions for kneading the organohydrogenpolysiloxane (B) and platinum or the platinum compound (E). Is the same as

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

[Elastic wiring board]
Hereinafter, an example of the stretchable wiring board (wiring board 50) will be described with reference to FIG. FIG. 1 is a cross-sectional view schematically illustrating an electronic device 100 (wearable device) including a stretchable wiring board.

  The electronic device 100 can include a wiring board 50 and an electronic component 60 as shown in FIG.

  The wiring substrate 50 (stretchable wiring substrate) is configured by providing the wiring 10 on the substrate 20. The substrate 20 contains an elastomer, and may be configured by curing the above-mentioned insulating paste. The wiring substrate 50 contacts at least the lower surface of the wiring 10 and is a member that supports the wiring 10.

  The wiring 10 may be formed by curing the above-mentioned conductive paste containing an elastomer and a conductive filler. The wiring 10 can have various wiring patterns such as a linear shape, a rectangular shape, and a winding shape in a top view.

The substrate 20 that constitutes 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.
The insulating paste is obtained by dissolving the elastomer composition (silicone rubber-based curable composition) obtained in step [2] in a solvent in the same manner as in the method for producing the conductive paste described above. .

  In this case, the content of the elastomer composition in the insulating paste is preferably 5% by mass or more, more preferably 8% by mass or more, and more preferably 10% by mass or more based on the whole insulating paste. It is more preferred that there be. Further, the content of the elastomer composition in the insulating paste is preferably 50% by mass or less, more preferably 45% by mass or less, and more preferably 40% by mass or less based on the whole insulating paste. Is more preferable. When a substrate is manufactured from an insulating paste, the substrate can be manufactured by applying an insulating paste to a support and then volatilizing a solvent. If necessary, the film from which the solvent has been volatilized may be cured by further heating.

  The upper limit of the content of the silica particles (C) may be, for example, 60 parts by weight or less, preferably 50 parts by weight or less, based on 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A). And more preferably 35 parts by weight or less. Thereby, balance of mechanical strength such as hardness and tensile strength can be achieved. The lower limit of the content of the silica particles (C) is not particularly limited to 100 parts by weight of the total amount of the vinyl group-containing organopolysiloxane (A), but may be, for example, 20 parts by weight or more.

The upper limit of the content of the silica particles (C) contained in the elastomer-containing substrate is, for example, preferably 60% by mass or less, more preferably 50% by mass or less, based on the whole substrate. , 40% by mass or less. The lower limit of the content of the silica particles (C) in the substrate is, for example, preferably 5% by mass or more, more preferably 10% by mass or more, and more preferably 15% by mass, based on the whole substrate. % Is more preferable.
By setting the content of the silica particles (C) in the substrate to the above lower limit or more, the substrate can have an appropriate mechanical strength. On the other hand, by setting the content of the silica particles (C) in the substrate to be equal to or less than the upper limit, the substrate can have an appropriate stretching property. Thereby, durability at the time of repeated use can be improved.

  In the present embodiment, the stretchable wiring board (wiring board 50) has a rigid structure in which H1, T1, and T2 satisfy the following formula (I). Such a rigid structure may be formed on at least a part of the stretchable wiring board, and may be formed over the entire area where the wiring is formed. In addition, in the laminated structure of the wiring board 50, the wiring 10 and the wiring 10 that is in contact with the lower surface of the wiring 10 only need to satisfy the rigid structure.

20 ≦ H1 × (T1 / T2) ≦ 1000 (I)
In the above formula (I), the substrate thickness T1 is the thickness (μm) of the unstretched substrate 20 and H1 is the type A durometer hardness at 25 ° C. of the unstretched substrate 20 according to JIS K6253 (1997). T2 is the thickness (μm) of the wiring 10 when it is not stretched.

  The lower limit of H1 × (T1 / T2) in the above formula (I) is 20 or more, preferably 30 or more, and more preferably 40 or more. Thereby, the characteristics at the time of extension can be improved. On the other hand, the upper limit of H1 × (T1 / T2) is 1000 or less, preferably 960 or less, and more preferably 930 or less. Thereby, suitability for wearable devices can be improved.

H1 (substrate hardness) in the above formula (I) is, for example, 20 to 80, preferably 25 to 75, and more preferably 30 to 70. By setting it within such a numerical range, the characteristics at the time of elongation can be further enhanced.
When the thickness of the substrate 20 is less than the predetermined thickness, for example, a plurality of cut pieces obtained by cutting out a part of the substrate 20 are stacked to form a sample having a predetermined thickness, and the hardness of the sample is set to “H1”. It may be.

  The substrate thickness T1 and the wiring thickness T2 can be measured as follows. This will be described with reference to FIG. FIG. 3 schematically shows a wiring board 50 for explaining a method of measuring the thickness. In FIG. 3A, the X axis, the Y axis, and the Z axis are orthogonal to each other in a three-dimensional space. The Z-axis direction is the thickness direction of the substrate or the wiring, the X-axis direction is the short direction (width direction) of the wiring having a rectangular shape in a top view, and the Y-axis direction is the longitudinal direction of the wiring having a rectangular shape in a top view. (Extending direction). FIG. 3B is a cross-sectional view taken along the line AA in FIG.

<Substrate thickness T1>
With respect to the thickness of the wiring board 50, five points surrounded by dotted lines in FIG. 3A are measured using a constant-pressure thickness measuring instrument. The five points need only be near the wiring 10 and are selected so that the distance between adjacent points is equal. The average value of the five thicknesses is defined as the substrate thickness T1.

<Wiring thickness T2>
The center in the width direction (X direction) of the wiring 10 is polished using an ion beam to obtain a cut surface. With respect to the obtained cut surface, an observation image is obtained using a scanning electron microscope (SEM) under the conditions of a visual field area: 600 μm × 480 μm, a visual field number: 1 visual field, and a magnification: 200 times. As shown in FIG. 3B, the thickness of the wiring 10 in the vicinity of the central portion is measured based on the observation image, and is defined as a wiring thickness T2.
In the case where the wiring 10 is an electrode pad having a rectangular shape in a top view, the cut surface may pass near the center of the electrode pad.

  The substrate thickness T1 is, for example, 5 μm to 5 mm, preferably 10 μm to 3 mm, and more preferably 15 μm to 1.5 mm. By setting the substrate thickness T1 to be equal to or more than the above lower limit, the insulating properties of the substrate can be improved, and the mechanical strength of the stretchable wiring substrate can be improved. When the substrate thickness T1 is equal to or less than the upper limit, the flexibility of the stretchable wiring substrate can be improved. In addition, manufacturing costs can be reduced.

  The wiring thickness T2 is, for example, 3 μm to 300 μm, preferably 5 μm to 200 μm, and more preferably 10 μm to 100 μm. By setting the wiring thickness T2 to be equal to or more than the above lower limit, the conductivity of the wiring can be improved, and the connectivity of the stretchable wiring board at the time of extension can be improved. By setting the wiring thickness T2 to the upper limit or less, the flexibility of the stretchable wiring substrate can be improved. In addition, manufacturing costs can be reduced.

  In the present embodiment, the substrate thickness T1 / wiring thickness T2 is, for example, 1.0 to 30.0, preferably 1.5 to 25.0, and more preferably 2.0 to 22.0. By adopting such a numerical value range, it is possible to balance the connection reliability at the time of 50% extension and the wearable compatibility.

  The lower limit of the tear strength of the substrate measured according to JIS K6252 (2001) is, for example, 25 N / mm or more, preferably 30 N / mm or more, and more preferably 33 N / mm or more. And more preferably 35 N / mm or more. Thereby, scratch resistance and mechanical strength can be improved. Further, the durability of the substrate when it is used repeatedly can be improved. On the other hand, the upper limit of the tear strength of the substrate is not particularly limited, but may be, for example, 70 N / mm or less, or may be 60 N / mm or less. Thereby, various characteristics of the cured product of the substrate can be balanced.

  The lower limit of the tensile strength of the substrate measured in accordance with JIS K6251 (2004) is, for example, 5.0 MPa or more, preferably 6.0 MPa or more, and more preferably 7.0 MPa or more. . Thereby, the mechanical strength of the substrate can be improved. On the other hand, the upper limit of the tensile strength of the substrate is not particularly limited, but may be, for example, 15 MPa or less, or 13 MPa or less. Thereby, the operability of the substrate can be improved.

  The lower limit of the elongation at break of the substrate measured according to JIS K6251 (2004) is, for example, 500% or more, preferably 700% or more, and more preferably 800% or more. Thereby, the high elasticity and durability of the substrate can be improved. On the other hand, the upper limit of the elongation at break of the substrate is not particularly limited, but may be, for example, 2000% or less, 1500% or less, or 1100% or less. Thereby, the mechanical strength of the substrate can be improved.

  In the present embodiment, for example, by appropriately selecting the type and blending amount of each component contained in the substrate or the wiring, a method for preparing a composition for forming the substrate or the wiring, a method for manufacturing a resin movable member, and the like. , H1 × (T1 / T2), tensile strength, tear strength and elongation at break can be controlled. Among these, for example, the type and blending ratio of the resin constituting the elastomer of the substrate and the wiring, the crosslinking density and the crosslinking structure of the resin are appropriately controlled, and the blending ratio of the inorganic filler and the dispersibility of the inorganic filler are controlled. Improvement is mentioned as an element for setting the above H1 × (T1 / T2), tensile strength, tear strength and elongation at break in a desired numerical range.

The wiring substrate 50 can maintain the electrical characteristics of the electronic device 100 when it is repeatedly expanded and contracted while increasing the mechanical strength, so that the structure of the electronic device 100 having excellent connection reliability and durability 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.

The electronic component 60 may be configured to be electrically connected to the wiring 10 constituting such an elastic wiring substrate (wiring substrate 50).
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, the 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): Organohydrogenpolysiloxane: “TC-25D” 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): Platinum or platinum compound: "TC-25A" manufactured by Momentive

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

(Metal powder (G))
(G1): silver powder, manufactured by Tokurika Chemical Laboratory Co., Ltd., trade name “TC-101”, median diameter d ₅₀ : 8.0 μm, aspect ratio 16.4, average major diameter 4.6 μm

(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-based curable composition)
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 1 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 the ratio shown in Table 1 below, and kneaded with a roll. Thus, silicone rubber-based curable compositions A to E (elastomer compositions) were obtained.

[Preparation of conductive paste]
The obtained 13.7 parts by weight of the silicone rubber-based curable composition E was immersed in 31.8 parts by weight of tetradecane (solvent), followed by stirring with a rotation / revolution mixer to obtain 54.5 parts by weight of metal. After adding the powder (G1), the mixture was kneaded with three rolls to obtain a liquid conductive paste.

[Preparation of stretchable wiring board]
(Examples 1 to 7, 11 and Comparative Example 2)
The obtained silicone rubber-based curable composition B was pressed at 170 ° C. and 10 MPa for 10 minutes, formed into a sheet having the thickness shown in Table 2, and primary 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 x a length: 5 cm to produce an elastomer "substrate".
Subsequently, using the obtained conductive paste, a wiring pattern was drawn on this “substrate” and cured at 180 ° C. for 120 minutes, and the thickness × width: 500 μm × length shown in Table 2 was obtained. Test pieces 1 to 7, 11, and 13 (stretchable wiring boards) having 30 mm of “wiring” were produced.

The measuring method of the substrate thickness T1 and the wiring thickness T2 is as follows.
<Substrate thickness T1>
With respect to the thickness of the wiring substrate 50, five points surrounded by a dotted line in FIG. 3A were measured using a constant-pressure thickness measuring instrument. Five points were close to the wiring 10 and were selected such that the distance between adjacent points was equal. The average value of the thickness at the five points was defined as the substrate thickness T1.
<Wiring thickness T2>
The center of the wiring 10 in the width direction (X direction) was polished using an ion beam to obtain a cut surface. With respect to the obtained cut surface, an observation image was obtained using a scanning electron microscope (SEM) under the conditions of a visual field region: 600 μm × 480 μm, the number of visual fields: 1 visual field, and the magnification: 200 times. As shown in FIG. 3B, the thickness of the wiring 10 in the vicinity of the central portion was measured based on the obtained observation image, and defined as the wiring thickness T2.

(Example 8)
A test piece 8 having a “substrate” having a thickness shown in Table 2 and a “wiring” having a thickness shown in Table 2 (stretchable wiring) in the same manner as in Example 1 except that the silicone rubber-based curable composition D was used. Substrate).

(Example 9)
A test piece 9 having a “substrate” having a thickness shown in Table 2 and a “wiring” having a thickness shown in Table 2 (stretchable wiring) in the same manner as in Example 1 except that the silicone rubber-based curable composition C was used. Substrate).

(Example 10, Comparative example 1)
Test pieces 10 and 12 (stretchable) having a “substrate” having a thickness shown in Table 2 and a “wiring” having a thickness shown in Table 2 in the same manner as in Example 1 except that the silicone rubber-based curable composition A was used. Wiring board).

<Hardness: Durometer hardness A>
Except that the thickness was 1 mm, sheet-like silicone rubbers (cured products of silicone rubber-based curable compositions) of each of Examples and Comparative Examples were obtained in the same manner as in [Preparation of Stretchable Wiring Board]. Six 1 mm thick sheets obtained were laminated to produce a 6 mm test piece. Using the obtained test piece, a type A durometer hardness at 25 ° C. was measured in accordance with JIS K6253 (1997).
The hardness was measured at n = 5 for each sample using two samples, and the average value of a total of 10 measurements was taken as the measured value. Table 2 shows the results.

<Tensile strength, elongation at break>
Except that the thickness was 1 mm, sheet-like silicone rubbers (cured products of silicone rubber-based curable compositions) of each of Examples and Comparative Examples were obtained in the same manner as in [Preparation of Stretchable Wiring Board]. Using the obtained elastomer layer having a thickness of 1 mm, a dumbbell-shaped No. 3 test piece was prepared according to JIS K6251 (2004), and the tensile strength and elongation at break of the obtained test piece at 25 ° C. were measured. did. The unit of the tensile strength is MPa. The elongation at break was calculated as [distance between chucks (mm)] ÷ [distance between initial chucks (60 mm)] × 100. The unit is%. Table 3 shows the results.
<Tear strength>
Except that the thickness was 1 mm, sheet-like silicone rubbers (cured products of silicone rubber-based curable compositions) of each of Examples and Comparative Examples were obtained in the same manner as in [Preparation of Stretchable Wiring Board]. Using the obtained sheet having a thickness of 1 mm, a crescent-type test piece was prepared in accordance with JIS K6252 (2001), and the tear strength of the obtained crescent-type test piece at 25 ° C. was measured. The unit is N / mm. Table 3 shows the results.

  The elongation at break and the tensile strength were performed on three samples, and three average values were used as measured values. The tear strength was measured for five samples, and the average of the five values was used as the measured value. Table 3 shows the results.

[Evaluation of stretchable wiring board]
The test pieces 1 to 13 of the obtained stretchable wiring board were evaluated according to the following evaluation items.

(Elongation characteristics: resistance measurement)
For the obtained test pieces 1 to 13 (stretchable wiring board), using a DC voltage / current source / monitor (6241A) manufactured by ADC Corporation, the resistance was measured and the length was increased by 50% in 3 seconds while measuring the resistance. Then, the test was held for 10 seconds, the elongation was released in 3 seconds, and the test was held 100 times for 100 seconds. The change in the resistance value (Ω) was constantly monitored, and the change in the resistance value during the test was analyzed (resistance value measurement at 50% elongation).
・ Maximum resistance value until the end of the 100th 50% elongation (50% R _MAX )
The above resistance values were measured for three samples, and three average values were used as measured values.

The obtained 50% R _MAX was evaluated based on the evaluation criteria shown in Table 4 below. Table 2 shows the evaluation results.
In addition, disconnection means that the measured value of a sample is a value of 10,000Ω or more and 11000Ω or less.

(Wearable compatibility)
Using the obtained test pieces 1 to 13 (stretchable wiring boards), the following bending / elongation test and durability test were performed.
Bending / elongation test: A test in which the plate-like member is bent at 90 degrees with both ends held by both hands, and the plate-like member is easily deformed by the ease of bending from the start to the end of bending. Was judged. During the bending test of the plate-shaped member, the plate-shaped member that did not feel a load when bending the plate-shaped member was marked with “、”, and the plate-shaped member that felt a load when bending the plate-shaped member was marked “x”.

  It was found that the stretchable wiring boards of Examples 1 to 11 were superior to Comparative Example 1 in the connection reliability at the time of elongation, and were superior to Comparative Example 2 in wearable suitability.

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

Claims (6)

A substrate containing an elastomer;
A stretchable wiring board that is in contact with one surface of the substrate and has a wiring containing an elastomer and a conductive filler,
The thickness of the substrate before unstretching is T1 (μm), the durometer hardness of the substrate at 25 ° C. according to JIS K6253 (1997) is H1 at 25 ° C., and the thickness of the wiring before unstretching is H1. Is T2 (μm),
A stretchable wiring board, wherein H1, T1, and T2 have a rigid structure satisfying the following formula (I).
20 ≦ H1 × (T1 / T2) ≦ 1000 (I) The stretchable wiring board according to claim 1,
H1 in the above formula (I) is 20 or more and 80 or less. The stretchable wiring board according to claim 1 or 2,
The elastomer contained in the substrate and the wiring includes silicone rubber, urethane rubber, fluorine rubber, nitrile rubber, acrylic rubber, styrene rubber, chloroprene rubber, and one or more selected from the group consisting of ethylene propylene rubber, Wiring board. The stretchable wiring board according to claim 1, wherein:
The substrate is a stretchable wiring substrate containing silica particles (C). The stretchable wiring board according to claim 1, wherein:
The stretchable wiring board, wherein the conductive filler contains metal, carbon, or a conductive polymer.   A wearable device comprising the elastic wiring board according to claim 1.

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