JP7392258B2 - Stretchable wiring boards and wearable devices - Google Patents

Description

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

In recent years, various developments have been made regarding materials used for wiring constituting stretchable wiring boards. As this type of technology, for example, the technology described in Patent Document 1 is known. Patent Document 1 describes an elastic wearable flexible substrate that includes a wearable housing made of an elastomer and a wiring layer disposed on the main surface of the wearable housing.

JP2016-076531A

However, upon study by the present inventor, it was found that the stretchable wiring board described in Patent Document 1 has room for improvement in terms of stretching characteristics and wearable suitability.

After further investigation, the inventor found that the stretching characteristics and wearable suitability of a stretchable wiring board can be appropriately controlled by using the stiffness parameter expressed as board hardness x (board thickness/wiring thickness) as a guideline. I found it. Based on this knowledge, we conducted further intensive research and found that by setting the stiffness parameter within a predetermined numerical range, the stretched characteristics and wearable suitability of the stretchable wiring board were improved, and the present invention was completed. reached.

According to the invention,
a substrate containing an elastomer;
A stretchable wiring board having a wiring that is placed on one surface of the substrate and contains an elastomer and a conductive filler,
The thickness of the substrate when unstretched is T1 (μm), the type A durometer hardness at 25°C according to JIS K6253 (1997) of the substrate when unstretched is H1, and the thickness of the wiring when unstretched is When is T2 (μm),
A stretchable wiring board is provided that has a rigid structure in which H1, T1, and T2 satisfy the following formula (I).
20≦H1×(T1/T2)≦1000...(I)

Further, according to the present invention,
A wearable device including the stretchable wiring board described above is provided.

According to the present invention, a stretchable wiring board with excellent properties when stretched and wearable suitability, and a wearable device using the same are provided.

FIG. 1 is a cross-sectional view schematically showing an electronic device according to an embodiment. FIG. 3 is a cross-sectional view schematically showing the manufacturing process of the electronic device according to the present embodiment. FIG. 3 is a diagram for explaining a method of measuring substrate thickness and wiring thickness.

Embodiments of the present invention will be described below with reference to the drawings. Note that in all the drawings, similar components are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate. In addition, in this specification, "-" represents the following unless otherwise specified.

The stretchable wiring board of this embodiment includes a board containing an elastomer, and wiring that is placed in contact with one surface of the board and contains the elastomer and a conductive filler.
The thickness of the substrate when not stretched is T1 (μm),
Type A durometer hardness at 25°C according to JIS K6253 (1997) of the unstretched substrate is H1,
When the thickness of the wiring when unstretched 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 the board hardness and the thickness ratio of the board and the wiring, stress on the wiring during stretching can be reduced while maintaining the ability to follow the body. It was found that wiring damage could be suppressed by
As a result of intensive studies based on such knowledge, we have determined that the stretching characteristics of a stretchable wiring board can be improved by combining two factors and using the stiffness parameter expressed as board hardness x (board thickness/wiring thickness) as a guideline. By appropriately controlling the wearable compatibility and by setting the stiffness parameter within a predetermined numerical range, the stretching characteristics and wearable compatibility of a stretchable wiring board having a rigid structure defined by the stiffness parameter can be improved. It was found that

Although the detailed mechanism is not clear, a rigid structure defined by appropriate rigidity parameters reduces stress on the wiring, suppresses wiring damage and increases in wiring resistance after repeated stretching, and improves the ability to follow the body. It is thought that it can increase the

The stretchable wiring board of this embodiment can be used for various purposes, and can be suitably used for wearable devices, for example.

Further, the stretchable wiring board of this embodiment suppresses wiring damage after repeated stretching, and therefore can achieve excellent connection reliability, that is, high durability.

Each structure of the stretchable wiring board of this embodiment will be described below.

The stretchable wiring board of this embodiment has at least a board containing an elastomer and wiring containing an elastomer and a conductive filler. The substrate is insulating and one of the wirings is conductive. Such a stretchable wiring board can exhibit appropriate stretchability and improve stretchable electrical characteristics.

The wiring may be made using conductive paste. The conductive paste can include an elastomer composition, a conductive filler, and a solvent. Wiring formed using conductive paste can exhibit appropriate stretchability.

The substrate may be made using an insulating paste. The insulating paste contains an elastomer composition and a solvent. A substrate made using such an insulating paste has excellent mechanical strength and insulation properties.

(elastomer)
The elastomer contained in the above board and wiring may include one or more selected from the group consisting of silicone rubber, urethane rubber, fluororubber, 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 these, the elastomer can include one or more thermosetting elastomers selected from the group consisting of silicone rubber, urethane rubber, and fluororubber. 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 a thermosetting elastomer composition. For example, the silicone rubber can be composed of a cured product of a silicone rubber-based curable composition. Note that the thermoplastic elastomer can be composed of a dried thermoplastic elastomer composition.

In this specification, the elastomer composition is used to constitute the elastomer contained in the above-mentioned substrate or wiring, and includes, for example, one or more types of thermosetting composition selected from the group consisting of silicone rubber, urethane rubber, and fluororubber. The composition may include a thermosetting elastomer composition used to form a rubber elastomer, preferably 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. Next, 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 this embodiment can contain a vinyl group-containing organopolysiloxane (A). The vinyl group-containing organopolysiloxane (A) is a polymer that is the main component of the silicone rubber curable composition of this embodiment.

The vinyl group-containing organopolysiloxane (A) may 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 vinyl groups, and the vinyl groups serve as crosslinking points during curing.

The vinyl group content of the vinyl group-containing linear organopolysiloxane (A1) is not particularly limited, but preferably has two or more vinyl groups in the molecule and is 15 mol% or less. , more preferably 0.01 to 12 mol%. Thereby, the amount of vinyl groups in the vinyl group-containing linear organopolysiloxane (A1) can be optimized, and a network with each component described below can be reliably formed. In this embodiment, "~" means that the numbers at both ends are included.

In addition, in this specification, the vinyl group content is the mol% of the vinyl group-containing siloxane unit when the total units constituting the vinyl group-containing linear organopolysiloxane (A1) is 100 mol%. . However, it is assumed that there is one vinyl group for one vinyl group-containing siloxane unit.

Further, 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, 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 degree of polymerization (or number average molecular weight) in terms of polystyrene in GPC (gel permeation chromatography) using chloroform as a developing solvent.

Further, 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 range, the heat resistance, flame retardance, chemical stability, etc. of the silicone rubber obtained can be improved. It is possible to improve the

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

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

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

Further, R ³ is a substituted or unsubstituted alkyl group having 1 to 8 carbon atoms, an aryl group, or a hydrocarbon group combining these. Examples of the alkyl group having 1 to 8 carbon atoms include methyl group, ethyl group, propyl group, etc. Among them, methyl group is preferred. Examples of the aryl group having 1 to 8 carbon atoms include phenyl group.

Further, examples of substituents for R ¹ and R ² in formula (1) include a methyl group and a vinyl group, and examples of substituents for R ³ include a methyl group.

In addition, in Formula (1), a plurality of R ¹ are mutually independent and may be different from each other or may be the same. Furthermore, the same applies to R ² and R ³ .

Further, m and n are the numbers of repeating units constituting the vinyl group-containing linear organopolysiloxane (A1) represented by formula (1), m is an integer of 0 to 2000, and n is 1000 to 10000. is an integer. m is preferably 0 to 1000, and n is preferably 2000 to 5000.

Further, specific structures of the vinyl group-containing linear organopolysiloxane (A1) represented by formula (1) include, for example, those represented by the following formula (1-1).

In 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.

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

Specifically, as the vinyl group-containing linear organopolysiloxane (A1), for example, in the above formula (1-1), a unit in which R ¹ is a vinyl group and/or a unit in which R ² is a vinyl group is used. , a first vinyl group-containing linear organopolysiloxane (A1-1) having two or more in the molecule and containing 0.4 mol% or less, and a unit in which 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 units in which ² is a vinyl group.

Further, the first vinyl group-containing linear organopolysiloxane (A1-1) preferably has a vinyl group content of 0.01 to 0.2 mol%, more preferably 0.02 to 0.15 mol%. is more preferable. Further, 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 blending the first vinyl group-containing linear organopolysiloxane (A1-1) and the second vinyl group-containing linear organopolysiloxane (A1-2) in combination, (A1-1) The ratio of (A1-2) and (A1-2) is not particularly limited, but for example, the weight ratio of (A1-1):(A1-2) is 50:50 to 95:5, preferably 60:40 to 92:8, or more. Preferably the ratio is 80:20 to 90:10.

Note that 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.

The vinyl group-containing organopolysiloxane (A) may also include a vinyl group-containing branched organopolysiloxane (A2) having a branched structure.

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

The linear organohydrogenpolysiloxane (B1) has a linear structure and a structure in which hydrogen is directly bonded to Si (≡Si-H), and is a vinyl group-containing organopolysiloxane (A). In addition to vinyl groups, it is a polymer that undergoes a hydrosilylation reaction with vinyl groups contained in components blended into a silicone rubber-based curable composition, thereby crosslinking these components.

The molecular weight of the linear organohydrogenpolysiloxane (B1) is not particularly limited, but, 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 in GPC (gel permeation chromatography) using chloroform as a developing solvent.

Further, it is generally preferable that the linear organohydrogenpolysiloxane (B1) does not have a vinyl group. Thereby, it is possible to accurately prevent the crosslinking reaction from proceeding within the molecules of the linear organohydrogenpolysiloxane (B1).

As the above linear organohydrogenpolysiloxane (B1), for example, one having a structure represented by the following formula (2) is preferably used.

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

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

In addition, in formula (2), a plurality of R ⁴ are mutually independent and may be different from each other or may be the same. The same applies to ^R5 . However, at least two or more of the plurality of R ⁴ and R ⁵ are hydride groups.

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

In addition, examples of substituents for R ⁴ , R ⁵ , and R ⁶ in formula (2) include a methyl group, a vinyl group, and the like, and a methyl group is preferable from the viewpoint of preventing intramolecular crosslinking reactions.

Furthermore, m and n are the numbers of repeating units constituting the linear organohydrogenpolysiloxane (B1) represented by formula (2), 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.

Note that 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 with a high crosslinking density, and is a component that greatly contributes to the formation of a dense and dense crosslinking structure in the silicone rubber system. In addition, like the above linear organohydrogenpolysiloxane (B1), it has a structure in which hydrogen is directly bonded to Si (≡Si-H), and in addition to the vinyl group of the vinyl group-containing organopolysiloxane (A), silicone It is a polymer that undergoes a hydrosilylation reaction with the vinyl groups of the components blended into the rubber-based curable composition and crosslinks these components.

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

Furthermore, it is preferable that the branched organohydrogenpolysiloxane (B2) usually does not have a vinyl group. Thereby, it is possible to accurately prevent the crosslinking reaction from proceeding within the molecules of the branched organohydrogenpolysiloxane (B2).

Further, as the branched organohydrogenpolysiloxane (B2), one represented by the following average composition formula (c) is preferable.

Average composition formula (c)
(H _a (R ⁷ ) _3-a SiO _1/2 ) _m (SiO _4/2 ) _n
(In formula (c), R ⁷ is a monovalent organic group, a is an integer in the range of 1 to 3, m is the number of H _a (R ⁷ ) _3-a SiO _1/2 units, and n is SiO _4/ (It is a number of ₂ units)

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

In 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 formula (c), m is the number of H _a (R ⁷ ) _3-a SiO _1/2 units, and n is the number of SiO _4/2 units.

The branched organohydrogenpolysiloxane (B2) has a branched structure. Linear organohydrogenpolysiloxane (B1) and branched organohydrogenpolysiloxane (B2) differ in that their structures are linear or branched. The number of bonded alkyl groups R (R/Si) is 1.8 to 2.1 in linear organohydrogenpolysiloxane (B1) and 0.8 to 1 in branched organohydrogenpolysiloxane (B2). The range is .7.

In addition, since the branched organohydrogenpolysiloxane (B2) has a branched structure, for example, the amount of residue when heated to 1000°C at a temperature increase 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 residue after heating under the above conditions becomes almost zero.

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

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

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

Furthermore, in formula (3), "-O-Si≡" represents that Si has a branched structure that extends three-dimensionally.

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

Further, 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, for 1 mole of vinyl groups in the vinyl group-containing linear organopolysiloxane (A1), linear organohydrogenpolysiloxane (B1) and branched organohydrogenpolysiloxane The total amount of hydride groups in the siloxane (B2) is preferably 0.5 to 5 mol, more preferably 1 to 3.5 mol. This ensures the formation of a crosslinked network 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 silicone rubber curable composition in the conductive paste is preferably 1% by mass or more, more preferably 3% by mass or more, based on the entire conductive paste. , 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 15% by mass or less, based on the entire conductive paste. % or less 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-mentioned 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) if necessary. Thereby, it is possible to improve the hardness and mechanical strength of the elastomer formed from the silicone rubber-based curable composition.

The conductive paste of this embodiment contains silica particles (C) in addition to the conductive filler, thereby improving the mechanical strength and durability of the elastomer made of the cured product of the conductive paste. I can do it. By using such a conductive paste to produce 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 with the conductive paste of this embodiment can be improved.

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

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

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

In this embodiment, the content of 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, the content is 3% by mass or more. Further, the content of silica particles (C) in the conductive paste is, for example, 20% by mass or less, preferably 15% by mass or less, and 12% by mass or less, based on the entire conductive paste. is more preferable, and even more preferably 10% by mass or less.
By setting the content of silica particles (C) to the above lower limit or more, the elastomer of the wiring produced using the conductive paste can have appropriate mechanical strength. Further, by controlling the content of silica particles (C) to be equal to or less than the above upper limit, wiring fabricated using a conductive paste can have appropriate conductive properties.

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

Moreover, this silane coupling agent (D) can contain a silane coupling agent having a hydrophobic group. As a result, this hydrophobic group is imparted to the surface of the silica particles (C), so that the cohesive force of the silica particles (C) decreases (hydrogen caused by silanol groups) in the silicone rubber-based curable composition and even in the silicone rubber. It is presumed that the dispersibility of silica particles in the silicone rubber-based curable composition is improved as a result. This increases the interface between the silica particles and the rubber matrix, increasing the reinforcing effect of the silica particles. Furthermore, it is presumed that upon deformation of the rubber matrix, the slipperiness of the silica particles within the matrix improves. By improving the dispersibility and slipperiness of the silica particles (C), the mechanical strength (for example, tensile strength, tear strength, etc.) of the silicone rubber due to the silica particles (C) is improved.

Furthermore, the silane coupling agent (D) can include a silane coupling agent having a vinyl group. As a result, vinyl groups are introduced onto the surface of the silica particles (C). Therefore, during curing of the silicone rubber-based curable composition, the vinyl groups of the vinyl group-containing organopolysiloxane (A) and the hydride groups of the organohydrogenpolysiloxane (B) undergo a hydrosilylation reaction. When a network (crosslinked structure) of these is formed, the vinyl groups of the silica particles (C) also participate in the hydrosilylation reaction with the hydride groups of the organohydrogenpolysiloxane (B), so Silica particles (C) also come to be taken in. This makes it possible to lower the hardness and increase the modulus of the silicone rubber formed.

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 from 1 to 3. Y represents a functional group having a hydrophobic group, a hydrophilic group, or a vinyl group; when n is 1, it is a hydrophobic group; when n is 2 or 3, at least one of them is a hydrophobic group; 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 combining these, such as a methyl group, an ethyl group, a propyl group, a phenyl group, among others, Methyl group is preferred.

Further, examples of the hydrophilic group include a hydroxyl group, a sulfonic acid group, a carboxyl group, and a carbonyl group, among which a hydroxyl group is particularly preferred. Note that, although the hydrophilic group may be included as a functional group, it is preferably not included from the viewpoint of imparting hydrophobicity to the silane coupling agent (D).

Furthermore, examples of the hydrolyzable group include a methoxy group, an alkoxy group such as an ethoxy group, a chloro group, and a silazane group, among which a silazane group is preferred because of its high reactivity with the silica particles (C). Note that those having a silazane group as a hydrolyzable group have two structures of (Y _n -Si-) in the above formula (4) due to their structural characteristics.

Specific examples of the silane coupling agent (D) represented by the above formula (4) are as follows.
Examples of the functional group having a hydrophobic group include methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, n-propyltrimethoxysilane, Alkoxysilanes such as n-propyltriethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane; chlorosilanes such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane; hexamethyldisilazane can be mentioned. Among these, a silane coupling agent having a trimethylsilyl group containing one or more selected from the group consisting of hexamethyldisilazane, trimethylchlorosilane, trimethylmethoxysilane, and trimethylethoxysilane is preferred.

Examples of those having a vinyl group as the functional group include methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, vinyltriethoxysilane, and vinyltrimethoxysilane. Alkoxysilanes such as silane and vinylmethyldimethoxysilane; chlorosilanes such as vinyltrichlorosilane and vinylmethyldichlorosilane; and divinyltetramethyldisilazane. Among these, methacryloxypropyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacryloxypropylmethyldimethoxysilane, divinyltetramethyldisilazane, vinyltriethoxysilane, vinyltrimethoxysilane, and vinyl A silane coupling agent having a vinyl group-containing organosilyl group containing one or more 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 vinyl group-containing organopolysiloxane (A), and 3% by mass or more. It is more preferably at least 5% by mass, even more preferably at least 5% by mass. Further, the upper limit of the content of the silane coupling agent (D) is preferably 100% by mass or less, and 80% by mass or less, based on 100 parts by weight of the vinyl group-containing organopolysiloxane (A). It is more preferable that the amount is 40% by mass or less.
By setting the content of the silane coupling agent (D) to the above lower limit value or more, the wiring formed using the conductive paste and the substrate containing the elastomer can have appropriate adhesion, and the silica particles ( When C) is used, it can contribute to improving the mechanical strength of the wiring and the board as a whole. Further, by controlling the content of the silane coupling agent (D) to be equal to or less than the above upper limit, the conductive resin film can have appropriate mechanical properties.

In addition, when the silane coupling agent (D) contains two types, a silane coupling agent having a trimethylsilyl group and a silane coupling agent having a vinyl group-containing organosilyl group, those having a hydrophobic group include hexamethyldisilazane, The vinyl group-containing compound preferably includes divinyltetramethyldisilazane.

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

<<Platinum or platinum compound (E)>>
The silicone rubber-based curable composition of this 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 platinum or platinum compound (E), known ones can be used, such as platinum black, platinum supported on silica, carbon black, etc., chloroplatinic acid or an alcoholic solution of chloroplatinic acid, chloroplatinic acid, etc. Examples include complex salts of platinic acid and olefins, complex salts of chloroplatinic acid and vinylsiloxane, and the like.

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

In this embodiment, the content of platinum or platinum compound (E) in the silicone rubber-based curable composition means a catalytic amount, and can be set appropriately, but specifically, the content of platinum or platinum compound (E) in the silicone rubber-based curable composition is The amount of platinum group metal is 0.01 to 1000 ppm by weight, preferably 0.01 to 1000 ppm by weight, based on 100 parts by weight of the total amount of (A), silica particles (C), and silane coupling agent (D). The amount is 1 to 500 ppm.
By setting the content of platinum or platinum compound (E) to the above lower limit or more, the silicone rubber-based curable composition can be cured at an appropriate speed. Further, by controlling the content of platinum or platinum compound (E) to be equal to or less than the above upper limit value, it is possible to contribute to reduction in manufacturing costs.

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

Water (F) functions as a dispersion medium for dispersing each component contained in the silicone rubber-based curable composition, and is a component 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.

Furthermore, when containing water (F), its content can be set as appropriate, but specifically, for example, 10 to 100 parts by weight per 100 parts by weight of the silane coupling agent (D). The amount is preferably in the range of 30 to 70 parts by weight, and more preferably 30 to 70 parts by weight. Thereby, the reaction between the silane coupling agent (D) and the silica particles (C) can proceed more reliably.

<<Organic peroxide (H)>>
The silicone rubber-based curable composition of this embodiment can contain an organic peroxide (H). Organic peroxide (H) is a component that acts as a catalyst. The organic peroxide (H) can be used in place of the organohydrogenpolysiloxane (B) and platinum or a platinum compound (E), or in combination with the organohydrogenpolysiloxane (B) and platinum or a platinum compound (E). (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 peroxydi Carbonates include, specifically, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, o-methylbenzoyl peroxide, dicumyl peroxide, 2,5-dimethyl- Examples include bis(2,5-t-butylperoxy)hexane, di-t-butyl peroxide, t-butylperbenzoate, 1,6-hexanediol-bis-t-butylperoxycarbonate, and the like.

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

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

(conductive filler)
The conductive paste of this embodiment contains a conductive filler. As this conductive filler, a known conductive material can be used.
For example, the elastomer constituting the wiring can contain, for example, metal, carbon, or a conductive polymer as a conductive filler. The conductive filler may be in the form of powder, fiber, or wire. These may be used alone or in combination of two or more.

The conductive filler may include metal powder (G).
The metal constituting the metal powder (G) is not particularly limited, but for example, at least one metal powder selected from copper, silver, gold, nickel, tin, lead, zinc, bismuth, antimony, or an alloy of these metal powders. , or two or more of these.
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.
Note that these metal powders (G) coated with other metals can also be used.

The shape of the metal powder (G) is not particularly limited, but scaly, dendritic, spherical, etc. are used. These may be used alone or in combination of two or more. Among these, it is preferable to use a scaly shape from the viewpoint of connection reliability during expansion and contraction.

The above-mentioned 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 nanotubes.

As the above-mentioned conductive polymer, a known one can be used, and for example, a single conductive polymer, a conductive polymer-coated fiber, etc. can be used.

In this 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. , more preferably 50% by mass or more. Further, the upper limit of the content of the conductive filler in the conductive paste is, for example, 90% by mass or less, preferably 85% by mass or less, and 75% by mass or less, based on the entire conductive paste. It is more preferably 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 entire wiring. , more preferably 50% by mass or more. Further, the upper limit of the content of the conductive filler 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. , more preferably 85% by mass or less.

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

In addition, the lower limit of the content of silica particles (C) in the wiring containing the elastomer and conductive filler is, for example, 1% by mass with respect to 100% by mass of the total amount of silica particles (C) and conductive filler. The content is preferably 3% by mass or more, 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 silica particles (C) in the wiring is, for example, 20% by mass or less, and preferably It is 15% by mass or less, more preferably 10% by mass or less. Thereby, it is possible to achieve a balance between the expansion/contraction electrical characteristics and the mechanical strength of the wiring.

(solvent)
The conductive paste of this embodiment contains a solvent. As this solvent, various known solvents can be used, and for example, high boiling point solvents 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 point 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. This makes it possible to suppress excessive thermal history during wiring formation, thereby preventing damage to the underlying substrate and maintaining the shape of the wiring formed with the conductive paste.

Further, the solvent of this embodiment can be appropriately selected from the viewpoint of solubility and boiling point of the elastomer composition, but for example, an aliphatic hydrocarbon having 5 to 20 carbon atoms, preferably 8 to 18 carbon atoms, It can contain an aliphatic hydrocarbon, more preferably an aliphatic hydrocarbon having 10 or more and 15 or less carbon atoms.

Further, examples of the solvents of this embodiment include aliphatic hydrocarbons such as pentane, hexane, cyclohexane, heptane, methylcyclohexane, ethylcyclohexane, octane, decane, dodecane, and tetradecane; benzene, toluene, ethylbenzene, and xylene. , trifluoromethylbenzene, benzotrifluoride, and other aromatic hydrocarbons; 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; haloalkanes such as dichloromethane, chloroform, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,1-trichloroethane, and 1,1,2-trichloroethane; Examples include carboxylic acid amides such as N,N-dimethylformamide and N,N-dimethylacetamide; and sulfoxides such as dimethyl sulfoxide and diethyl sulfoxide. These may be used alone or in combination of two or more.
The solvent used here may be appropriately selected from solvents that can uniformly dissolve or disperse the composition components in the conductive paste.

The lower limit of the viscosity of the conductive paste when measured at a room temperature of 25°C and 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. s or more. Thereby, film formability can be improved. Further, shape retention can be improved even when forming a thick film. 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 for manufacturing conductive paste)
Hereinafter, a method for manufacturing a conductive paste according to this embodiment will be described.

The conductive paste of this embodiment can be manufactured, for example, through the steps shown below.

First, each component of the silicone rubber-based curable composition is uniformly mixed using an arbitrary kneading device to prepare a silicone rubber-based curable composition.

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

Note that this kneaded product is preferably obtained by kneading the vinyl group-containing organopolysiloxane (A) and the silane coupling agent (D) in advance, and then kneading (mixing) the silica particles (C). This further improves the dispersibility of the silica particles (C) in the vinyl group-containing organopolysiloxane (A).

Moreover, when obtaining this kneaded product, water (F) may be added to the kneaded product of each component (A), (C), and (D) as needed. Thereby, the reaction between the silane coupling agent (D) and the silica particles (C) can proceed more reliably.

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

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

Further, 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.

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

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

[2] Next, predetermined amounts of organohydrogenpolysiloxane (B) and platinum or platinum compound (E) are weighed, and then, using an arbitrary kneading device, the kneaded product prepared in the above step [1] A silicone rubber curable composition (elastomer composition) is obtained by kneading each component (B) and (E).

In addition, when kneading these components (B) and (E), the kneaded product prepared in advance in the above step [1] and the organohydrogenpolysiloxane (B) prepared in the above step [1] It is preferable to knead the kneaded material and platinum or the platinum compound (E), and then knead each kneaded material. This ensures that each component (A) to (E) is incorporated into the silicone rubber curable composition without proceeding with the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B). can be dispersed into

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

Furthermore, the kneading time is preferably about 5 minutes to 1 hour, more preferably about 10 to 40 minutes.

In the above step [1] and the above step [2], by setting the temperature within the above range, the reaction between the vinyl group-containing organopolysiloxane (A) and the organohydrogenpolysiloxane (B) can proceed more accurately. Can be prevented or suppressed. In addition, in the above step [1] and the above step [2], each component (A) to (E) can be more reliably dispersed in the silicone rubber curable composition by keeping the kneading time within the above range. I can do it.

The kneading device used in each step [1] and [2] is not particularly limited, and for example, a kneader, two rolls, Banbury mixer (continuous kneader), pressure kneader, etc. can be used.

Further, in this 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) can be more accurately prevented or suppressed. be able to.

In addition, in this step [2], instead of the organohydrogenpolysiloxane (B) and platinum or the platinum compound (E), or in combination with the organohydrogenpolysiloxane (B) and platinum or the platinum compound (E), , an organic peroxide (H) may be added. Preferred conditions such as temperature and time when kneading the organic peroxide (G) and the equipment to be used are the conditions when kneading the organohydrogenpolysiloxane (B) and platinum or platinum compound (E). It is similar to

[3] Next, the elastomer composition (silicone rubber curable composition) obtained in step [2] is dissolved in a solvent, and a conductive filler (metal powder (G)) is added to make it conductive. You can get a paste.

[Stretchable wiring board]
An example of a stretchable wiring board (wiring board 50) will be described below with reference to FIG. FIG. 1 shows a schematic cross-sectional view of 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 board 50 (stretchable wiring board) is configured by providing the wiring 10 on the board 20. The substrate 20 may contain an elastomer and may be made of a cured insulating paste. The wiring board 50 is in contact with at least the lower surface of the wiring 10 and is a member that supports the wiring 10.

The wiring 10 contains an elastomer and a conductive filler, and may be made of a hardened conductive paste. The wiring 10 may have various wiring patterns such as a linear shape, a rectangular shape, and a coiled shape when viewed from above.

The substrate 20 that constitutes the electronic device 100 of this embodiment is usually made of a flexible material.
As this material, the same material as the above-mentioned elastomer can be used. Specifically, silicone rubber, urethane rubber, fluororubber, nitrile rubber, acrylic rubber, styrene rubber, chloroprene rubber, ethylene propylene rubber, etc. can be used, and the material can be selected as appropriate depending on the application. . Further, the substrate 20 may be made of a cured product of the above-mentioned silicone rubber-based curable composition.

Moreover, the substrate 20 can be produced using the above-mentioned elastomer composition. Further, the substrate 20 may be configured using an insulating paste containing an elastomer composition containing silica particles and a solvent. As this solvent, the above-mentioned solvent types similar to the above-mentioned solvents can be used, but among these, a solvent that is soluble in the above-mentioned conductive paste or a conductive sheet that is a cured product of the conductive paste is used. be able to. As a specific solvent for the insulating paste, for example, a high boiling point solvent 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 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 10% by mass or more, based on the entire insulating paste. It is even more preferable 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 40% by mass or less based on the entire insulating paste. It is even more preferable. When producing a substrate from an insulating paste, it can be produced by applying the insulating paste to a support and then volatilizing the solvent. If necessary, the film from which the solvent has been volatilized may be cured by further heating.

Further, 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). , more preferably 35 parts by weight or less. This makes it possible to balance mechanical strengths such as hardness and tensile strength. Further, 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.

Further, the upper limit of the content of silica particles (C) contained in a substrate containing an elastomer is preferably, for example, 60% by mass or less, and more preferably 50% by mass or less, based on the entire substrate. , more preferably 40% by mass or less. Further, the lower limit of the content of silica particles (C) in the substrate is, for example, preferably 5% by mass or more, more preferably 10% by mass or more, and 15% by mass or more, based on the entire substrate. % or more is more preferable.
By setting the content of silica particles (C) in the substrate to the above lower limit or more, the substrate can have appropriate mechanical strength. On the other hand, by controlling the content of silica particles (C) in the substrate to be equal to or less than the above upper limit, the substrate can have appropriate elastic properties. Thereby, durability during repeated use can be improved.

In this 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 portion of the stretchable wiring board, and may be formed over the entire area where wiring is formed. Further, in the laminated structure of the wiring board 50, the wiring 10 and the wiring 10 in contact with the lower surface of the wiring 10 may satisfy the above-mentioned rigid structure.

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

The lower limit value 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 properties during elongation 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, more preferably 30 to 70. By setting it within such a numerical range, the properties upon elongation can be further improved.
In addition, if the thickness of the substrate 20 is less than a predetermined thickness, for example, a plurality of pieces cut out from a part of the substrate 20 are laminated to create a sample with a predetermined thickness, and the hardness of this sample is set to "H1". You can also use it as

The substrate thickness T1 and the wiring thickness T2 can be measured as follows. This will be explained using FIG. 3. FIG. 3 schematically shows a wiring board 50 for explaining the thickness measurement method. In FIG. 3(a), the X-axis, Y-axis, and Z-axis are orthogonal to each other in three-dimensional space. The Z-axis direction is the thickness direction of the board and wiring, the X-axis direction is the short direction (width direction) of the wiring that is rectangular in top view, and the Y-axis direction is the longitudinal direction of the wiring that is rectangular in top view. (extending direction). FIG. 3(b) is a cross-sectional view taken along the line AA in FIG. 3(a).

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

<Wiring thickness T2>
The center of the wiring 10 in the width direction (X direction) is polished using an ion beam to obtain a cut surface. An observation image of the obtained cut surface is obtained using a scanning electron microscope (SEM) under the following conditions: viewing area: 600 μm x 480 μm, number of fields: 1 field, and magnification: 200 times. As shown in FIG. 3B, the thickness near the center of the wiring 10 is measured based on the observed image, and is defined as the wiring thickness T2.
Note that when the wiring 10 is an electrode pad having a rectangular shape in 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 greater than the above lower limit, it is possible to improve the insulation properties of the substrate and the mechanical strength of the stretchable wiring board. By setting the substrate thickness T1 to be less than or equal to the above upper limit value, the flexibility of the stretchable wiring board can be improved. Also, 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 greater than the above lower limit value, conductivity of the wiring can be improved, and connectivity when the stretchable wiring board is stretched can be improved. By setting the wiring thickness T2 to be less than or equal to the above upper limit value, the flexibility of the stretchable wiring board can be improved. Also, manufacturing costs can be reduced.

Further, in this 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 setting such a numerical value range, it is possible to achieve a balance between connection reliability at 50% expansion and wearable suitability.

The lower limit of the tear strength of the substrate measured in accordance with 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. , more preferably 35 N/mm or more. Thereby, scratch resistance and mechanical strength can be improved. Furthermore, the durability of the substrate during repeated use 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 60 N/mm or less. Thereby, various properties 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 board can be improved.

The lower limit of the elongation at break of the substrate measured in accordance with JIS K6251 (2004) is, for example, 500% or more, preferably 700% or more, and more preferably 800% or more. This makes it possible to improve the high elasticity and durability of the substrate. 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 this embodiment, for example, by appropriately selecting the types and amounts of each component contained in the substrate and wiring, the method for preparing the composition for forming the substrate and wiring, the method for manufacturing the resin movable member, etc. , the above H1×(T1/T2), tensile strength, tear strength, and elongation at break can be controlled. Among these, for example, it is important to appropriately control the type and blending ratio of the resin that makes up the elastomer for substrates and wiring, the crosslinking density and crosslinking structure of the resin, and the blending ratio and dispersibility of the inorganic filler. Improving the above-mentioned H1×(T1/T2), tensile strength, tear strength, and elongation at break are listed as factors for bringing the above-mentioned H1×(T1/T2), tensile strength, tear strength, and elongation at break into desired numerical ranges.

The wiring board 50 can maintain the electrical properties of expansion and contraction when it is repeatedly expanded and contracted while increasing its mechanical strength, so that it is possible to realize a structure of the electronic device 100 that has excellent connection reliability and durability.
The electronic device 100 of this embodiment is used, for example, as a wearable device, and can be suitably used for a device that is repeatedly expanded and contracted in each direction.

The electronic component 60 may be configured to be electrically connected to the wiring 10 forming such a stretchable wiring board (wiring board 50).
Further, the electronic component 60 may be appropriately selected from known components depending on the application.
Specifically, examples include semiconductor elements, and resistors and capacitors other than semiconductor elements. Examples of semiconductor elements include transistors, diodes, LEDs, capacitors, and the like. In the electronic device 100 of this embodiment, the electronic component 60 is electrically connected by the wiring 10.

Furthermore, the electronic device 100 of the present embodiment may be provided with a cover material 30 if necessary. By providing this cover material 30, it is possible to prevent the wiring 10 and electronic components 60 from being damaged. The cover material 30 may be configured to cover the electronic components 60 and the wiring 10 on the board 20.
Further, the cover material 30 can be made of the same material as the substrate 20. Since the cover material 30 follows the expansion and contraction of the substrate 20 and the wiring 10, the electronic device 100 as a whole can expand and contract evenly, which can also contribute to extending the life of the electronic device 100.

Next, an example of the manufacturing process of the electronic device 100 of this embodiment will be described using FIG. 2.
FIG. 2 is a cross-sectional view schematically showing the manufacturing process of the electronic device 100 in this embodiment.

First, as shown in FIG. 2A, a support 120 is placed on a workbench 110, and an insulating paste 130 is applied onto the support 120. Various methods can be used as the coating method, and for example, a printing method such as a squeegee method using a squeegee 140 can be used. Subsequently, the film-like insulating paste 130 can be dried to form an insulating layer 132 (dried insulating sheet) on the support 120. The drying conditions can be set as appropriate depending on the type and amount of solvent in the insulating paste 130, but for example, the drying temperature may be set to 150° C. to 180° C., and the drying time may be set to 1 minute to 30 minutes. can.

Subsequently, as shown in FIG. 2B, a mask 160 having a predetermined opening pattern shape is placed on the insulating layer 132. Then, as shown in FIGS. 2B and 2C, a conductive paste 150 is applied onto the insulating layer 132 through a mask 160. The coating method may be the same as the coating method of the insulating paste 130, and for example, squeegee printing using the squeegee 140 may be used. Here, when the insulating paste 130 and the conductive paste 150 each contain a thermosetting elastomer composition, a conductive coating film (conductive layer 152) having a predetermined pattern shape is laminated on the dried insulating layer 132. Afterwards, these may be cured all at once. The curing treatment can be appropriately set depending on the thermosetting elastomer composition, and for example, the curing temperature can be set to 160° C. to 220° C., and the curing time can be set to 1 hour to 3 hours. After or before the curing process, the mask 160 can be removed as shown in FIG. 2(d). Thereby, it is possible to form wiring, which is the cured product of the conductive layer 152, and has a predetermined pattern shape on the substrate made of the cured product of the insulating layer 132.

Subsequently, as shown in FIG. 2(e), 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. 2(f). can be formed. These steps may be repeated as appropriate. It is also possible to separate the support 120 from the insulating layer 132.
Through the above steps, the electronic device 100 shown in FIG. 2(f) can be obtained.

In addition, when replacing with an insulating paste and using an insulating sheet, you may start from the process shown in FIG.2(b). That is, after an insulating sheet is placed on the support 120 and a predetermined drying process is performed, the conductive paste 150 may be applied onto the insulating sheet through the mask 160. Subsequent steps can be performed according to the steps described above. Thereby, it is possible to obtain the electronic device 100 shown in FIG. 2(f).

Note that the present invention is not limited to the above-described embodiments, and the present invention includes modifications, improvements, etc. within a range that can achieve the purpose of the present invention.
Below, examples of reference forms will be added.
1. a substrate containing an elastomer;
A stretchable wiring board having a wiring that is placed on one surface of the substrate and contains an elastomer and a conductive filler,
The thickness of the substrate when unstretched is T1 (μm), the type A durometer hardness at 25°C according to JIS K6253 (1997) of the substrate when unstretched is H1, and the thickness of the wiring when unstretched is When is T2 (μm),
A stretchable wiring board having a rigid structure in which H1, T1, and T2 satisfy the following formula (I).
20≦H1×(T1/T2)≦1000...(I)
2. 1. The stretchable wiring board according to
H1 in the above formula (I) is a stretchable wiring board, wherein H1 is 20 or more and 80 or less.
3. 1. or 2. The stretchable wiring board according to
The elastomer contained in the substrate and the wiring is a stretchable elastomer containing one or more selected from the group consisting of silicone rubber, urethane rubber, fluororubber, nitrile rubber, acrylic rubber, styrene rubber, chloroprene rubber, and ethylene propylene rubber. wiring board.
4. 1. From 3. The stretchable wiring board according to any one of
The substrate is a stretchable wiring substrate containing silica particles (C).
5. 1. From 4. The stretchable wiring board according to any one of
A stretchable wiring board, wherein the conductive filler includes metal, carbon, or a conductive polymer.
6. 1. From 5. A wearable device comprising the stretchable wiring board according to any one of the above.

EXAMPLES The present invention will be explained below 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 is 0.13 mol%, Mn = 227,734, Mw = 573,903, IV value (dl/g) = 0.89), vinyl group-containing dimethylpolysiloxane (structure represented by the above formula (1-1)) synthesized by the following synthesis scheme 1
(A1-2): Second vinyl group-containing linear organopolysiloxane: Vinyl group content is 0.92 mol%, vinyl group-containing dimethylpolysiloxane synthesized according to the following synthesis scheme 2 (formula (1- Structure represented by 1) in which 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 size 7 nm, specific surface area 300 m ² /g), “AEROSIL 300” manufactured by Nippon Aerosil Co., Ltd.

(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 Tokuriki Kagaku Kenkyusho Co., Ltd., product name "TC-101", median diameter _d50 : 8.0 μm, aspect ratio 16.4, average major axis 4.6 μm

(Synthesis of vinyl group-containing organopolysiloxane (A))
[Synthesis scheme 1: Synthesis of first vinyl group-containing linear organopolysiloxane (A1-1)]
A first vinyl group-containing linear organopolysiloxane (A1-1) was synthesized according to the following formula (5).
That is, 74.7 g (252 mmol) of octamethylcyclotetrasiloxane and 0.1 g of potassium siliconate were placed in a 300 mL separable flask equipped with a cooling tube and stirring blade and replaced with Ar gas, and heated to 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.
Furthermore, after 4 hours, the mixture was diluted with 250 mL of toluene and washed three times with water. The organic layer after washing was washed several times with 1.5 L of methanol to purify it by reprecipitation and separate the oligomer and polymer. The obtained polymer was dried under reduced pressure at 60° C. overnight to obtain a first vinyl group-containing linear organopolysiloxane (A1-1) (Mw=573,903, Mn=227,734). Further, 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) above, in addition to 74.7 g (252 mmol) of octamethylcyclotetrasiloxane, 0.2 g (252 mmol) of 2,4,6,8-tetramethyl 2,4,6,8-tetravinylcyclotetrasiloxane. The second vinyl group-containing linear organopolysiloxane ( A1-2) was synthesized. Furthermore, the vinyl group content calculated by H-NMR spectrum measurement was 0.92 mol%.

(Preparation of silicone rubber-based curable composition)
Silicone rubber-based curable composition 1 was prepared as follows.
First, a mixture of a 90% vinyl group-containing organopolysiloxane (A), a silane coupling agent (D), and water (F) is kneaded in advance in the proportions shown in Table 1 below, and then the silica particles ( C) was added and further kneaded to obtain a kneaded product (silicone rubber compound).
Here, the kneading after addition of the silica particles (C) includes the first step of kneading for 1 hour at 60 to 90°C under a nitrogen atmosphere for the coupling reaction, and the removal of by-products (ammonia). For this purpose, a second step of kneading for 2 hours at 160 to 180°C under a reduced pressure atmosphere is performed, followed by cooling and adding the remaining 10% of the vinyl group-containing organopolysiloxane (A) twice. Added in portions and kneaded for 20 minutes.
Subsequently, organohydrogenpolysiloxane (B), platinum or platinum compound (E) were added to 100 parts by weight of the obtained kneaded product (silicone rubber compound) in the proportions shown in Table 1 below, and the mixture was kneaded with a roll. Then, silicone rubber-based curable compositions A to E (elastomer compositions) were obtained.

[Preparation of conductive paste]
13.7 parts by weight of the silicone rubber-based curable composition E thus obtained was immersed in 31.8 parts by weight of tetradecane (solvent), and then stirred with an autorotation/revolution mixer to dissolve 54.5 parts by weight of metal. A liquid conductive paste was obtained by adding powder (G1) and kneading with three rolls.

[Fabrication of stretchable wiring board]
(Examples 1 to 7, 11, Comparative Example 2)
The obtained silicone rubber-based curable composition B was pressed at 170° C. and 10 MPa for 10 minutes to form a sheet having the thickness shown in Table 2, and was primarily cured. Subsequently, secondary curing was performed at 200° C. for 4 hours to obtain a sheet-like silicone rubber (cured product of a silicone rubber-based curable composition). It was cut into a piece of width: 2 cm x length: 5 cm to produce an elastomer "substrate".
Subsequently, a wiring pattern was drawn on this "substrate" using the obtained conductive paste, and this was cured at 180° C. for 120 minutes to obtain the thickness x width: 500 μm x length shown in Table 2. Test pieces 1 to 7, 11, and 13 (stretchable wiring boards) having "wiring" of 30 mm were prepared.

The method for measuring the substrate thickness T1 and the wiring thickness T2 is as follows.
<Substrate thickness T1>
The thickness of the wiring board 50 was measured at five points surrounded by dotted lines in FIG. 3(a) using a constant pressure thickness measuring device. The five points are close to the wiring 10 and selected so that the distances between adjacent points are equal. The average value of the thicknesses at 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. An observation image of the obtained cut surface was obtained using a scanning electron microscope (SEM) under the following conditions: viewing area: 600 μm x 480 μm, number of fields: 1 field, and magnification: 200 times. As shown in FIG. 3B, the thickness near the center of the wiring 10 was measured based on the obtained observation image, and was defined as the wiring thickness T2.

(Example 8)
Test piece 8 (stretchable wiring A substrate) was prepared.

(Example 9)
Test piece 9 (stretchable wiring) was prepared in the same manner as in Example 1, except that silicone rubber-based curable composition C was used. A substrate) was prepared.

(Example 10, Comparative Example 1)
Test specimens 10 and 12 (expandable A flexible wiring board) was fabricated.

<Hardness: Durometer hardness A>
Sheet-shaped silicone rubbers (cured products of silicone rubber-based curable compositions) of each Example and each Comparative Example were obtained in the same manner as in [Preparation of stretchable wiring board] except that the thickness was 1 mm. Six of the obtained 1 mm thick sheets were laminated to produce a 6 mm test piece. Using the obtained test piece, the type A durometer hardness at 25°C was measured in accordance with JIS K6253 (1997).
Regarding hardness, two samples were used, and each sample was measured with n=5, and the average value of a total of 10 measurements was taken as the measured value. The results are shown in Table 2.

<Tensile strength, elongation at break>
Sheet-shaped silicone rubbers (cured products of silicone rubber-based curable compositions) of each Example and each Comparative Example were obtained in the same manner as in [Preparation of stretchable wiring board] except that the thickness was 1 mm. Using the obtained elastomer layer with a thickness of 1 mm, a dumbbell-shaped No. 3 test piece was prepared in accordance with 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 tensile strength is MPa. The elongation at break was calculated by [moving distance between chucks (mm)]÷[initial distance between chucks (60 mm)]×100. The unit is %. The results are shown in Table 3.
<Tear strength>
Sheet-shaped silicone rubbers (cured products of silicone rubber-based curable compositions) of each Example and each Comparative Example were obtained in the same manner as in [Preparation of stretchable wiring board] except that the thickness was 1 mm. Using the obtained sheet with a thickness of 1 mm, a crescent-shaped test piece was prepared according to JIS K6252 (2001), and the tear strength at 25° C. of the obtained crescent-shaped test piece was measured. The unit is N/mm. The results are shown in Table 3.

The elongation at break and the tensile strength were measured on three samples, and the average value of the three was taken as the measured value. The tear strength was measured using five samples, and the average value of the five samples was taken as the measured value. The results are shown in Table 3.

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

(Stretching characteristics: resistance value measurement)
The obtained test pieces 1 to 13 (stretchable wiring board) were stretched by 50% in the length direction in 3 seconds while measuring the resistance using a DC voltage/current source/monitor (6241A) manufactured by ADC Co., Ltd. A test was conducted 100 times in which the extension was held for 10 seconds, the extension was released after 3 seconds, and the extension was held for 10 seconds. Changes in this resistance value (Ω) were constantly monitored, and changes in resistance value during this test were analyzed (resistance value measurement at 50% elongation).
・Maximum resistance value until the end of the 100th 50% extension (50%R _MAX )
The above resistance values were measured using three samples, and the average value of the three was taken as the measured value.

The obtained 50%R _MAX was evaluated based on the evaluation criteria shown in Table 4 below. The evaluation results are shown in Table 2.
Note that a disconnection refers to a measured value of a sample of 10,000Ω or more and 11,000Ω or less.

(Wearable suitability)
Using the obtained test pieces 1 to 13 (stretchable wiring board), the following bending/elongation tests and durability tests were conducted.
Bending/extension test: A test is conducted in which both ends of the plate-shaped member are held in both hands and the plate-shaped member is bent at 90 degrees. judged. During a test for bending a plate-like member, a plate-like member that did not feel a load when bending the plate-like member was marked as ○, and a plate-like member that felt a load when bending the plate-like member was marked as ×.

It was found that the stretchable wiring boards of Examples 1 to 11 had better connection reliability when stretched than Comparative Example 1, and had better wearable suitability than Comparative Example 2.

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 having a wiring that is placed on one surface of the substrate and contains an elastomer and a conductive filler,
The conductive filler contains scale-like metal powder (G),
The content of the conductive filler in the wiring is 50% by mass or more and 95% by mass or less, and the content of the scaly metal powder (G) is out of 100% by mass of the conductive filler, 90% by mass or more and 100% by mass or less,
After the stretchable wiring board is stretched by 50% in 3 seconds, held for 10 seconds, and released from the stretch in 3 seconds, the wiring does not break,
The thickness of the substrate when unstretched is T1 (μm), the type A durometer hardness at 25°C according to JIS K6253 (1997) of the substrate when unstretched is H1, and the thickness of the wiring when unstretched is When is T2 (μm),
A stretchable wiring board having a rigid structure in which H1, T1, and T2 satisfy 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 a stretchable wiring board, wherein H1 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 is a stretchable elastomer containing one or more selected from the group consisting of silicone rubber, urethane rubber, fluororubber, nitrile rubber, acrylic rubber, styrene rubber, chloroprene rubber, and ethylene propylene rubber. wiring board. The stretchable wiring board according to any one of claims 1 to 3,
The substrate is a stretchable wiring substrate containing silica particles (C). The stretchable wiring board according to any one of claims 1 to 4,
A stretchable wiring board, wherein the conductive filler includes metal, carbon, or a conductive polymer. A wearable device comprising the stretchable wiring board according to claim 1 .

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