JP7486042B2 - Wiring board and method for manufacturing the same - Google Patents

Description

An embodiment of the present disclosure relates to a wiring board having a stretchable substrate and wiring, and a method for manufacturing the same.

In recent years, research has been conducted into electronic devices that have deformation properties such as elasticity. For example, devices that have elastic silver wiring formed on an elastic substrate and devices that have horseshoe-shaped wiring formed on an elastic substrate are known (see, for example, Patent Document 1). However, these types of electronic devices have the problem that the resistance value of the wiring is easily changed as the substrate expands and contracts.

As another type of electronic device, for example, Patent Document 2 discloses a stretchable wiring board that includes a substrate and wiring provided on the substrate. Patent Document 2 employs a manufacturing method in which a circuit is provided on a substrate in a pre-stretched state, and the substrate is relaxed after the circuit is formed. Patent Document 2 intends to ensure that thin-film transistors on the substrate operate satisfactorily whether the substrate is stretched or relaxed.

JP 2013-187308 A JP 2007-281406 A

When the substrate is in a relaxed state, the wiring provided on the substrate has a bellows-shaped portion in which peaks and valleys appear repeatedly along the in-plane direction of the substrate. In this case, when the substrate is stretched, the wiring can follow the expansion of the substrate by expanding the bellows-shaped portion in the in-plane direction. Therefore, with an electronic device of the type having a bellows-shaped portion, it is possible to suppress changes in the resistance value of the wiring due to the expansion and contraction of the substrate.

On the other hand, the height of the peaks and the depth of the valleys of the bellows-shaped portion may vary from position to position due to variations in the thickness of the substrate, variations in the elongation of the substrate when stretched, and differences in the distribution density of the wiring provided on the substrate. Furthermore, if the substrate stretches significantly, the period of the bellows-shaped portion may be disrupted, causing the height of the peaks and the depth of the valleys to increase locally. If the height of the peaks and the depth of the valleys vary from position to position, the degree of curvature or bending of the wiring will also increase locally. In particular, if the substrate stretches significantly, it is conceivable that the wiring may be damaged, such as by breaking.

The embodiment of the present disclosure aims to provide a wiring board and a method for manufacturing a wiring board that can effectively solve these problems.

One embodiment of the present disclosure is a wiring board comprising: a base material having elasticity, including a first surface and a second surface located on the opposite side of the first surface; wiring located on the first surface side of the base material and having a bellows-shaped portion including a plurality of peaks and valleys aligned along a first direction, which is one of the in-plane directions of the first surface of the base material; and an adjustment mechanism located on the first surface side of the base material, having a side edge extending in the first direction with a gap between it and the wiring when viewed along the normal direction of the first surface, and including a resin or elastomer on a surface thereof.

In a wiring board according to one embodiment of the present disclosure, the adjustment mechanism may be positioned to sandwich the wiring in a second direction perpendicular to the first direction.

In a wiring board according to one embodiment of the present disclosure, the adjustment mechanism may include an adjustment layer having a lower elastic modulus than the wiring.

In a wiring board according to one embodiment of the present disclosure, the adjustment mechanism may include an adjustment layer having a bending stiffness or elastic modulus higher than that of the substrate.

In a wiring board according to one embodiment of the present disclosure, the wiring may include a base material and conductive particles.

In a wiring board according to one embodiment of the present disclosure, the adjustment mechanism may have a higher occupancy rate on the first surface side of the base material than the wiring.

In a wiring board according to one embodiment of the present disclosure, the adjustment mechanism may have a dimension in a second direction perpendicular to the first direction that is equal to or greater than the width of the wiring, for example, may have a dimension that is at least twice the width of the wiring.

In a wiring board according to one embodiment of the present disclosure, the distance between the side edge of the adjustment mechanism and the wiring may be equal to or less than the width of the wiring, and may be equal to or less than 100 μm.

In a wiring board according to one embodiment of the present disclosure, the adjustment mechanism may have a bellows-shaped portion including a plurality of peaks and valleys aligned along the first direction.

In a wiring board according to an embodiment of the present disclosure, the amplitude of the peaks and valleys appearing on the surface of the wiring board on the second surface side of the substrate that overlaps the bellows-shaped portion of the wiring may be different from the amplitude of the peaks and valleys appearing on the surface of the wiring board on the first surface side of the substrate that overlaps the bellows-shaped portion of the wiring, and may be smaller than the amplitude of the peaks and valleys appearing on the surface of the wiring board on the first surface side of the substrate that overlaps the bellows-shaped portion of the wiring, for example.

In a wiring board according to an embodiment of the present disclosure, the period of the peaks and valleys appearing on the surface of the wiring board on the second surface side of the substrate that overlaps the bellows-shaped portion of the wiring may be different from the period of the peaks and valleys appearing on the surface of the wiring board on the first surface side of the substrate that overlaps the bellows-shaped portion of the wiring, and may be, for example, larger than the period of the peaks and valleys appearing on the surface of the wiring board on the first surface side of the substrate that overlaps the bellows-shaped portion of the wiring.

In a wiring board according to an embodiment of the present disclosure, the positions of the peaks and valleys appearing in the portion of the surface of the wiring board on the second side of the base material that overlaps the bellows-shaped portion of the wiring may be shifted from the positions of the peaks and valleys appearing in the portion of the surface of the wiring board on the first side of the base material that overlaps the bellows-shaped portion of the wiring.

In a wiring board according to one embodiment of the present disclosure, when the tension applied to the wiring board and the electrical resistance of the wiring are measured while the wiring board is stretched in the first direction, the electrical resistance may indicate a first turning point where the increase in the electrical resistance per unit of stretch changes when the amount of stretch of the wiring board in the first direction is a first stretch amount, and the tension may indicate a second turning point where the increase in the tension per unit of stretch changes when the amount of stretch of the wiring board in the first direction is a second stretch amount that is smaller than the first stretch amount.

In a wiring board according to one embodiment of the present disclosure, the first extension amount may be 1.1 times or more the second extension amount.

In a wiring board according to one embodiment of the present disclosure, when the extension amount of the wiring board in the first direction is smaller than the second extension amount, the increase in tension per unit extension amount is referred to as a first tension increase rate, and when the extension amount of the wiring board in the first direction is larger than the second extension amount, the increase in tension per unit extension amount is referred to as a second tension increase rate, and the second tension increase rate may be larger than the first tension increase rate.

In a wiring board according to one embodiment of the present disclosure, the second tension increase rate may be at least twice the first tension increase rate.

In a wiring board according to one embodiment of the present disclosure, when the extension amount of the wiring board in the first direction is smaller than the first extension amount, the increase in the electrical resistance per unit extension amount is referred to as a first electrical resistance increase rate, and when the extension amount of the wiring board in the first direction is larger than the first extension amount, the increase in the electrical resistance per unit extension amount is referred to as a second electrical resistance increase rate, and the second electrical resistance increase rate may be larger than the first electrical resistance increase rate.

In a wiring board according to one embodiment of the present disclosure, the second electrical resistance increase rate may be at least twice the first electrical resistance increase rate.

In a wiring board according to one embodiment of the present disclosure, the base material may include a thermoplastic elastomer, a silicone rubber, a urethane gel, or a silicon gel.

The wiring substrate according to one embodiment of the present disclosure may further include a support substrate.

In a wiring board according to one embodiment of the present disclosure, the support substrate may have a higher elastic modulus than the base material and may support the wiring.

In a wiring board according to one embodiment of the present disclosure, the support substrate may be located between the wiring and the first surface of the base material and support the wiring.

In a wiring board according to one embodiment of the present disclosure, the support substrate may include polyethylene naphthalate, polyimide, polycarbonate, acrylic resin, or polyethylene terephthalate.

The wiring board according to one embodiment of the present disclosure may further include an electronic component electrically connected to the wiring.

One embodiment of the present disclosure is a method for manufacturing a wiring board, comprising: a first elongation step of applying tension to an elastic substrate in a first direction, which is one of the in-plane directions of the first surface of the substrate, to elongate the substrate; a wiring formation step of providing wiring extending in the first direction on the first surface side of the substrate in a state elongated by the first elongation step; an adjustment mechanism formation step of providing an adjustment mechanism containing a resin or elastomer on a surface of the first surface side of the substrate in a state elongated, the adjustment mechanism having a side edge extending in the first direction with a gap between the wiring when viewed along the normal direction of the first surface; and a contraction step of removing the tension from the substrate.

In a method for manufacturing a wiring board according to an embodiment of the present disclosure, when the tension applied to the wiring board and the electrical resistance of the wiring are measured while the wiring board is stretched in the first direction, the electrical resistance may indicate a first turning point where the increase in the electrical resistance per unit of stretch changes when the amount of stretch of the wiring board in the first direction is a first stretch amount, and the tension may indicate a second turning point where the increase in the tension per unit of stretch changes when the amount of stretch of the wiring board in the first direction is a second stretch amount that is smaller than the first stretch amount.

In the adjustment mechanism forming step of the method for manufacturing a wiring board according to one embodiment of the present disclosure, the adjustment mechanism may be provided on the first surface side of the substrate in a state in which the substrate is stretched at a smaller stretch rate than in the first stretching step after the wiring is provided on the substrate.

According to the embodiment of the present disclosure, it is possible to prevent defects such as breakage of components such as wiring.

1 is a plan view showing a wiring board according to an embodiment; 2 is a cross-sectional view taken along line AA of the wiring board of FIG. 1. 2 is a cross-sectional view taken along line BB of the wiring board of FIG. 1. 3 is an enlarged cross-sectional view showing the wiring board of FIG. 2. 4 is an enlarged cross-sectional view showing the wiring board of FIG. 3. 11 is another example of a cross-sectional view of a wiring board. 11 is another example of a cross-sectional view of a wiring board. 11 is another example of a cross-sectional view of a wiring board. 1A to 1C are diagrams for explaining a method for manufacturing a wiring board. FIG. 11 is a cross-sectional view showing a wiring board according to a first modified example. 11A to 11C are diagrams for explaining a method for manufacturing a wiring board according to a first modified example. 11A to 11C are diagrams for explaining a method for manufacturing a wiring board according to a first modified example. 11A and 11B are diagrams illustrating an example of how tension and electrical resistance of wiring change when a wiring board is stretched. 11 is a cross-sectional view showing the wiring board in a state in which it is stretched by a second stretch amount. FIG. FIG. 11 is a cross-sectional view showing a wiring board according to a second modified example. FIG. 11 is a cross-sectional view showing a wiring board according to a second modified example. 16 is an enlarged cross-sectional view showing the wiring board of FIG. 15 . 13A to 13C are diagrams for explaining a method for manufacturing a wiring board according to a second modified example. FIG. 13 is a cross-sectional view showing a wiring board according to a third modified example. FIG. 13 is a cross-sectional view showing a wiring board according to a fourth modified example. FIG. 13 is a plan view showing a wiring board according to a fifth modified example. FIG. 13 is a plan view showing a wiring board according to a sixth modified example. 23 is a cross-sectional view taken along line CC of the wiring board of FIG. 22.

The configuration of the wiring board according to the embodiment of the present disclosure and the manufacturing method thereof will be described in detail below with reference to the drawings. Note that the embodiment shown below is an example of the embodiment of the present disclosure, and the present disclosure is not to be interpreted as being limited to these embodiments. In this specification, terms such as "substrate", "base material", "sheet" and "film" are not distinguished from each other based only on the difference in name. For example, "substrate" is a concept that includes members that can be called base material, sheet and film. Furthermore, terms such as "parallel" and "orthogonal" and values of length and angle that specify the shape and geometric conditions and their degree used in this specification are not bound by strict meanings, but are interpreted to include the range in which similar functions can be expected. In addition, in the drawings referred to in this embodiment, the same parts or parts having similar functions are given the same or similar symbols, and repeated explanations may be omitted. In addition, the dimensional ratios of the drawings may differ from the actual ratios for the convenience of explanation, and some of the configurations may be omitted from the drawings.

Below, one embodiment of the present disclosure will be described with reference to Figures 1 to 9.

(Wiring board)
First, a description will be given of a wiring board 10 according to the present embodiment. Fig. 1 is a plan view showing the wiring board 10. Fig. 2 is a cross-sectional view taken along line A-A of the wiring board 10 in Fig. 1, and Fig. 3 is a cross-sectional view taken along line B-B of the wiring board 10 in Fig. 1.

The wiring board 10 shown in FIG. 1 includes at least a base material 20, wiring 52, and an adjustment mechanism 30. Each component of the wiring board 10 will be described below.

〔Base material〕
The substrate 20 is a member configured to have elasticity in at least one direction. The substrate 20 includes a first surface 21 located on the wiring 52 side and a second surface 22 located on the opposite side of the first surface 21. In the example shown in FIG. 1, the substrate 20 has a quadrangular shape including a pair of sides extending in a first direction D1 and a pair of sides extending in a second direction D2 when viewed along the normal direction of the first surface 21. The first direction D1 and the second direction D2 may be orthogonal to each other as shown in FIG. 1, or may not be orthogonal to each other (not shown). In the following description, viewing the wiring board 10 or components of the wiring board 10 along the normal direction of the first surface 21 is also simply referred to as "planar view". In this embodiment, the substrate 20 has elasticity at least in the first direction D1. The substrate 20 may also have elasticity in directions other than the first direction D1.

The thickness of the substrate 20 is, for example, 10 μm or more and 10 mm or less, and more preferably 20 μm or more and 3 mm or less. By making the thickness of the substrate 20 10 μm or more, the durability of the substrate 20 can be ensured. Furthermore, by making the thickness of the substrate 20 10 mm or less, the wearing comfort of the wiring board 10 can be ensured. Note that if the thickness of the substrate 20 is made too small, the elasticity of the substrate 20 may be impaired.

The elasticity of the substrate 20 refers to the property of the substrate 20 being able to expand and contract, that is, the property of being able to expand from a non-stretched state, which is the normal state, and being able to restore when released from this stretched state. The non-stretched state is the state of the substrate 20 when no tensile stress is applied. In this embodiment, the stretchable substrate can preferably be stretched from a non-stretched state by 1% or more without being broken, more preferably by 20% or more, and even more preferably by 75% or more. By using a substrate 20 having such capabilities, the wiring board 10 can be made elastic as a whole. Furthermore, the wiring board 10 can be used in products and applications that require high elasticity, such as attachment to a part of the body, such as a human arm. In general, it is said that products that are attached to a person's armpits require elasticity of 72% in the vertical direction and 27% in the horizontal direction. It is also said that products that are attached to a person's knees, elbows, buttocks, ankles, and armpits require elasticity of 26% or more and 42% or less in the vertical direction. It is also said that products that are attached to other parts of the person require elasticity of less than 20%.

It is also preferable that the difference between the shape of the substrate 20 in an unstretched state and the shape of the substrate 20 when it is stretched from the unstretched state and then returns to the unstretched state is small. This difference is also referred to as shape change in the following description. The shape change of the substrate 20 is, for example, 20% or less in area ratio, more preferably 10% or less, and even more preferably 5% or less. By using a substrate 20 with small shape change, it becomes easier to form the peaks and valleys described below.

An example of a parameter that represents the elasticity of the substrate 20 is the elastic modulus of the substrate 20. The elastic modulus of the substrate 20 is, for example, 10 MPa or less, and more preferably 1 MPa or less. By using a substrate 20 having such an elastic modulus, the entire wiring board 10 can be made elastic. In the following description, the elastic modulus of the substrate 20 is also referred to as the first elastic modulus. The first elastic modulus of the substrate 20 may be 1 kPa or more.

As a method for calculating the first elastic modulus of the substrate 20, a tensile test can be performed in accordance with JIS K6251 using a sample of the substrate 20. In addition, a method can be adopted in which the elastic modulus of the sample of the substrate 20 is measured by a nanoindentation method in accordance with ISO14577. A nanoindenter can be used as a measuring device used in the nanoindentation method. As a method for preparing a sample of the substrate 20, a method of taking out a part of the substrate 20 from the wiring board 10 as a sample, or a method of taking out a part of the substrate 20 before constructing the wiring board 10 as a sample can be considered. In addition, as a method for calculating the first elastic modulus of the substrate 20, a method of analyzing the material constituting the substrate 20 and calculating the first elastic modulus of the substrate 20 based on an existing database of materials can be adopted. Note that the elastic modulus in this application is an elastic modulus in an environment of 25°C.

Another example of a parameter representing the stretchability of the substrate 20 is the bending rigidity of the substrate 20. The bending rigidity is the product of the second moment of area of the target member and the elastic modulus of the material constituting the target member, and is expressed in units of N· ^m2 or Pa· ^m4 . The second moment of area of the substrate 20 is calculated based on a cross section of a portion of the substrate 20 overlapping with the wiring 52 cut by a plane perpendicular to the stretch direction of the wiring board 10.

An example of a material constituting the substrate 20 is an elastomer. In addition, the substrate 20 may be made of a cloth such as a woven fabric, a knitted fabric, or a nonwoven fabric. As the elastomer, a general thermoplastic elastomer and a thermosetting elastomer may be used. Specifically, a polyurethane-based elastomer, a styrene-based elastomer, a nitrile-based elastomer, an olefin-based elastomer, a PVC-based elastomer, an ester-based elastomer, an amide-based elastomer, a 1,2-BR-based elastomer, a fluorine-based elastomer, a silicone rubber, a urethane rubber, a fluorine rubber, a polybutadiene, a polyisobutylene, a polystyrene butadiene, a polychloroprene, or the like may be used. In consideration of mechanical strength and abrasion resistance, it is preferable to use a urethane-based elastomer. In addition, the substrate 20 may contain a silicone such as polydimethylsiloxane. Silicone has excellent heat resistance, chemical resistance, and flame retardancy, and is therefore preferable as a material for the substrate 20.

〔wiring〕
The wiring 52 is a conductive member having an elongated shape in a planar view. In the example shown in FIG. 1 , the wiring 52 extends in a first direction D1, which is one of the in-plane directions of the first surface 21 of the base material 20.

In this embodiment, the wiring 52 is located on the first surface 21 side of the substrate 20. As shown in FIG. 2, the wiring 52 may be in contact with the first surface 21 of the substrate 20. Although not shown, other members may be interposed between the first surface 21 of the substrate 20 and the wiring 52.

The material of the wiring 52 is a material that can follow the expansion and contraction of the base material 20 by utilizing the elimination and generation of a bellows-shaped portion described later. The material of the wiring 52 may or may not have elasticity by itself.
Examples of materials that do not have elasticity and that can be used for the wiring 52 include metals such as gold, silver, copper, aluminum, platinum, and chromium, and alloys containing these metals. When the material of the wiring 52 itself does not have elasticity, a metal film can be used for the wiring 52.
When the material used for the wiring 52 itself has elasticity, the elasticity of the material is, for example, the same as that of the substrate 20. Examples of materials that can be used for the wiring 52 and that have elasticity themselves include conductive compositions containing conductive particles and elastomers. The conductive particles may be any particles that can be used for wiring, and examples of the conductive particles include particles of gold, silver, copper, nickel, palladium, platinum, carbon, etc. Among these, silver particles are preferably used.

Preferably, the wiring 52 has a structure that is resistant to deformation. For example, the wiring 52 has a base material and a plurality of conductive particles dispersed in the base material. In this case, by using a deformable material such as resin as the base material, the wiring 52 can also deform in response to the expansion and contraction of the substrate 20. In addition, the conductivity of the wiring 52 can be maintained by setting the distribution and shape of the conductive particles so that contact between the plurality of conductive particles is maintained even if deformation occurs.

As the material constituting the base material of the wiring 52, general thermoplastic elastomers and thermosetting elastomers can be used, such as styrene-based elastomers, acrylic-based elastomers, olefin-based elastomers, urethane-based elastomers, silicone rubber, urethane rubber, fluororubber, nitrile rubber, polybutadiene, polychloroprene, etc. can be used. Among these, resins and rubbers containing urethane-based and silicone-based structures are preferably used in terms of their elasticity and durability. In addition, as the material constituting the conductive particles of the wiring 52, particles of silver, copper, gold, nickel, palladium, platinum, carbon, etc. can be used. Among these, silver particles are preferably used.

The thickness of the wiring 52 may be any thickness that can withstand the expansion and contraction of the base material 20, and is appropriately selected depending on the material of the wiring 52, etc.
For example, if the material of the wiring 52 is not elastic, the thickness of the wiring 52 can be in the range of 25 nm to 100 μm, preferably in the range of 50 nm to 50 μm, and more preferably in the range of 100 nm to 5 μm.
Furthermore, when the material of the wiring 52 is elastic, the thickness of the wiring 52 can be in the range of 5 μm or more and 60 μm or less, preferably in the range of 10 μm or more and 50 μm or less, and more preferably in the range of 20 μm or more and 40 μm or less.
The width of the wiring 52 is, for example, not less than 50 μm and not more than 10 mm.

The width of the wiring 52 is appropriately selected according to the electrical resistance value required for the wiring 52. The width of the wiring 52 is, for example, 1 μm or more, and preferably 50 μm or more. The width of the wiring 52 is, for example, 10 mm or less, and preferably 1 mm or less.

The method of forming the wiring 52 is appropriately selected depending on the material, etc. For example, a method of forming a metal film on the base material 20 or the support substrate 40 described later by deposition, sputtering, lamination of metal foil, etc., and then patterning the metal film by photolithography can be used. When laminating metal foil on the base material 20 or the support substrate 40 described later, an adhesive layer or the like may be interposed between the base material 20 or the support substrate 40 and the metal foil. In addition, when the material of the wiring 52 itself has elasticity, for example, a method of printing a conductive composition containing the above-mentioned conductive particles and elastomer in a pattern on the base material 20 or the support substrate 40 by a general printing method can be used. Among these methods, a printing method that has good material efficiency and can be produced inexpensively can be preferably used.

[Adjustment mechanism]
The adjustment mechanism 30 is a mechanism provided on the first surface 21 side of the substrate 20 to control the expansion and contraction of the substrate 20. The adjustment mechanism 30 is provided over a wide area of the substrate 20. For example, the adjustment mechanism 30 has a higher occupancy rate on the first surface 21 side of the substrate 20 than the wiring 52. Therefore, compared to a case where the adjustment mechanism 30 is not provided, it is possible to suppress localized concentration of stress on a part of the wiring substrate 10 when the wiring substrate 10 is expanded or contracted. For example, when the difference between the elastic modulus of the substrate 20 and the elastic modulus of the wiring 52 is large and the occupancy rate of the wiring 52 is low, stress is likely to concentrate on the wiring 52 when the wiring substrate 10 is expanded or contracted. In contrast, according to the present embodiment, by providing the adjustment mechanism 30 on the substrate 20, it is possible to suppress the concentration of stress on the wiring 52. As a result, it is possible to suppress deformation such as curvature and bending occurring in the wiring substrate 10 from becoming locally large. Therefore, it is possible to suppress the occurrence of damage such as cracks in the wiring 52. In addition, it is possible to suppress an increase in the electrical resistance value of the wiring 52 when the wiring substrate 10 is repeatedly expanded or contracted.

The "occupancy rate of the adjustment mechanism" is the ratio of the area of all the adjustment mechanisms 30 located on the first surface 21 side when viewed along the normal direction of the first surface 21 of the substrate 20 to the area of the entire wiring board 10 when viewed along the normal direction of the first surface 21 of the substrate 20. Similarly, the "occupancy rate of the wiring" is the ratio of the area of all the wiring 52 located on the first surface 21 side when viewed along the normal direction of the first surface 21 of the substrate 20 to the area of the entire wiring board 10 when viewed along the normal direction of the first surface 21 of the substrate 20.

However, the inventors of the present invention conducted extensive research and found that when the adjustment mechanism 30 is in contact with the wiring 52, the electrical properties of the wiring 52 are likely to deteriorate. For example, when the wiring 52 is entirely covered by the adjustment mechanism 30, the electrical resistance of the wiring 52 can increase by more than five times before and after a stretching test in which the wiring board 10 is repeatedly stretched 10,000 times. This increase in electrical resistance is evident when the wiring 52 has a base material and a plurality of conductive particles dispersed in the base material, and the surface of the adjustment mechanism 30 that is in contact with the wiring 52 contains a resin or elastomer.

Considering these problems, in this embodiment, it is proposed to provide the adjustment mechanism 30 so that the adjustment mechanism 30 does not overlap the wiring 52 at all or almost does not overlap the wiring 52. For example, as shown in FIG. 1, it is proposed to provide the adjustment mechanism 30 with a gap Z1 between it and the wiring 52 in a plan view. In this case, the adjustment mechanism 30 has a side edge 30e that extends in the first direction D1 with a gap Z1 between it and the wiring 52. By providing the adjustment mechanism 30 in this manner, it is possible to prevent the electrical resistance value of the wiring 52 from increasing due to contact between the wiring 52 and the adjustment mechanism 30. The gap Z1 between the wiring 52 and the side edge 30e of the adjustment mechanism 30 is preferably 1 μm or more, and more preferably 3 μm or more.

On the other hand, if the distance Z1 becomes too large, it becomes difficult for the adjustment mechanism 30 to have the effect of suppressing the concentration of stress on the wiring 52. It is preferable that the distance Z1 between the wiring 52 and the side edge 30e of the adjustment mechanism 30 is equal to or less than the width of the wiring 52. Furthermore, the distance Z1 is, for example, 1 mm or less, and may be 500 μm or less, 100 μm or less, 10 μm or less, or 7 μm or less.

Preferably, the adjustment mechanisms 30 are provided at a higher density in the portions of the wiring board 10 where the wiring 52 is not provided. The ratio of the area of the adjustment mechanisms 30 to the area of the portions of the wiring board 10 where the wiring 52 is not provided is, for example, 50% or more, may be 60% or more, 70% or more, 80% or more, 90% or more, or may be 95% or more.

As shown in FIG. 1, the adjustment mechanism 30 may be positioned to sandwich the wiring 52 in a second direction D2 perpendicular to the first direction D1 in which the wiring 52 extends. In this case, the distance between the adjustment mechanism 30 located on one side of the wiring 52 in the second direction D2 and the wiring 52 and the distance between the adjustment mechanism 30 located on the other side of the wiring 52 in the second direction D2 and the wiring 52 may be the same or different. Also, although not shown, the adjustment mechanism 30 may be positioned only on one side or the other side of the wiring 52 in the second direction D2.

In FIG. 1, the symbol W1 represents the dimension of the wiring 52 in the second direction D2 perpendicular to the first direction D1, and the symbol W2 represents the dimension of the adjustment mechanism 30 in the second direction D2. In the following description, the dimension of the wiring 52 in the second direction D2 perpendicular to the first direction D1 is also referred to as the width of the wiring 52. The dimension W2 of the adjustment mechanism 30 may be at least twice the width W1 of the wiring 52, and is more preferably at least five times.

3, the adjustment mechanism 30 includes at least an adjustment layer 31 extending in the in-plane direction of the first surface 21 on the first surface 21 side. The adjustment layer 31 may have a higher elastic modulus than the first elastic modulus of the substrate 20 in the first direction D1. The elastic modulus of the adjustment layer 31 may be lower than the elastic modulus of the wiring 52. The elastic modulus of the adjustment layer 31 is, for example, 10 GPa or more and 500 GPa or less, more preferably 1 GPa or more and 300 GPa or less. If the elastic modulus of the adjustment layer 31 is too low, the extension of the substrate 20 may not be suppressed. If the elastic modulus of the adjustment layer 31 is too high, the structure of the adjustment layer 31 may be destroyed, such as by cracking or cracking, when the substrate 20 expands and contracts. The elastic modulus of the adjustment layer 31 may be 1.1 times or more and 5000 times or less than the first elastic modulus of the substrate 20, more preferably 10 times or more and 3000 times or less. In the following description, the elastic modulus of the adjustment layer 31 is also referred to as the second elastic modulus.

The material of the adjustment layer 31 may or may not be elastic. In particular, it is preferable that the material of the adjustment layer is elastic. This is because when the adjustment layer 31 contains an elastic material, it can have resistance to deformation.

An example of a material that does not have elasticity and is used for the adjustment layer 31 is a resin. As the resin, a general resin can be used, and for example, any of a thermoplastic resin, a thermosetting resin, a photocurable resin, etc. can be used. In addition, when the adjustment layer 31 contains a resin or an elastomer, a resin substrate can also be used as the adjustment layer.

The elasticity of the elastic material used in the adjustment layer 31 can be the same as that of the base material 20 .
Examples of materials having elasticity used for the adjustment layer 31 include elastomers. As the elastomers, general thermoplastic elastomers and thermosetting elastomers can be used, and specifically, styrene-based elastomers, olefin-based elastomers, urethane-based elastomers, amide-based elastomers, silicone rubber, urethane rubber, fluororubber, polybutadiene, polyisobutylene, polystyrene butadiene, polychloroprene, and the like can be mentioned. When the material constituting the adjustment layer 31 is these resins, the adjustment layer 31 may have transparency. In addition, the adjustment layer may have a light-shielding property, for example, a property of shielding ultraviolet rays. For example, the adjustment layer 31 may be black. In addition, the color of the adjustment layer and the color of the substrate may be the same. The adjustment layer 31 may have a design property and serve as a decoration.

The adjustment layer 31 may also be insulating. Resins and elastomers can be used as materials for the adjustment layer 31 that have insulating properties.

The method for calculating the second elastic coefficient of the adjustment layer 31 is appropriately determined depending on the form of the adjustment layer 31. For example, the method for calculating the second elastic coefficient of the adjustment layer 31 may be the same as or different from the method for calculating the elastic coefficient of the base material 20 described above. The same applies to the elastic coefficient of the support substrate 40 described below. For example, a method for calculating the elastic coefficient of the adjustment layer 31 or the support substrate 40 can be adopted in which a tensile test is performed in accordance with ASTM D882 using a sample of the adjustment layer 31 or the support substrate 40.

The adjustment mechanism 30 may have a surface that includes a resin or an elastomer. When the adjustment mechanism 30 is made of an adjustment layer 31 as shown in FIG. 3, the surface of the adjustment mechanism 30 that includes a resin or an elastomer can be realized by the adjustment layer 31 including a resin or an elastomer.

The thickness of the adjustment layer 31 may be any thickness that can withstand expansion and contraction, and is appropriately selected according to the material of the adjustment layer 31. The thickness of the adjustment layer 31 may be, for example, 0.1 μm or more, 1 μm or more, or 10 μm or more. The thickness of the adjustment layer 31 may be, for example, 5 mm or less, 1 mm or less, 500 μm or less, or 100 μm or less. If the adjustment layer 31 is too thin, the effect of reducing stress concentration may not be sufficiently obtained. If the adjustment layer 31 is too thick, even if the elastic coefficient of the adjustment layer 31 satisfies the above-mentioned relationship, the bending rigidity of the adjustment layer 31 may be large, making it difficult to reduce stress concentration.

The characteristics of the adjustment layer 31 may be expressed by bending rigidity instead of the elastic modulus. The second moment of area of the adjustment layer 31 is calculated based on a cross section of the adjustment layer 31 cut by a plane perpendicular to the direction in which the wiring 52 extends. The bending rigidity of the adjustment layer 31 may be 1.1 times or more, more preferably 2 times or more, and even more preferably 10 times or more, of the bending rigidity of the base material 20. The bending rigidity is the product of the second moment of area of the target member and the elastic modulus of the material constituting the target member, and is expressed in units of N·m ² or Pa·m ⁴ .

The method for forming the adjustment layer 31 is appropriately selected depending on the material, etc. For example, after forming the wiring 52 on the base material 20 or on the support substrate 40 described below, the material constituting the adjustment layer 31 is printed on the base material 20 by a printing method. The member constituting the adjustment layer 31, such as a metal foil or a resin film, may be attached to the base material 20 via an adhesive layer, etc.

Next, the cross-sectional shape of the wiring board 10 will be described in detail. First, the cross-sectional shape of the portion of the wiring board 10 that includes the wiring 52 will be described with reference to FIG. 4. FIG. 4 is an enlarged view of the wiring board of FIG. 2, which is a cross-sectional view taken along line A-A that passes through the wiring 52.

As described below, the wiring 52 is provided on the substrate 20 in a state in which tension is applied and the substrate 20 is stretched by a first extension amount. In this case, when the tension is removed from the substrate 20 and the substrate 20 contracts, the wiring 52 is deformed into a bellows shape and has a bellows-shaped portion 55 as shown in FIG. 4.

The bellows-shaped portion 55 of the wiring 52 includes a plurality of peaks 53 aligned along the first direction D1 in which the wiring 52 extends. The peaks 53 are raised portions on the surface of the wiring 52 in the normal direction of the first face 21. As shown in FIG. 4, a valley 54 may be present between two peaks 53 adjacent to each other in the direction in which the wiring 52 extends.

In the example shown in FIG. 4, the peaks 53 and valleys 54 of the wiring 52 and the peaks 23 and valleys 24 of the first surface 21 of the substrate 20 are aligned in the first direction D1, which is the direction in which the sides of the substrate 20 extend. That is, the direction in which the peaks 53 and valleys 54 of the wiring 52 and the peaks 23 and valleys 24 of the first surface 21 of the substrate 20 are aligned coincides with the direction in which the sides of the substrate 20 extend. However, this is not limited to this, and although not shown, the direction in which the peaks 53 and valleys 54 of the wiring 52 and the peaks 23 and valleys 24 of the first surface 21 of the substrate 20 are aligned does not have to coincide with the direction in which the sides of the substrate 20 extend. Also, in FIG. 4, an example in which multiple peaks 53 and valleys 54 of the bellows-shaped portion 55 are aligned at a constant period is shown, but this is not limited to this. Although not shown, the multiple peaks 53 and valleys 54 of the bellows-shaped portion 55 may be arranged irregularly along the first direction D1. For example, the distance between two adjacent peaks 53 in the first direction D1 may not be constant.

In FIG. 4, the symbol S1 represents the amplitude of the peaks and valleys that appear on the surface of the wiring board 10 on the first surface 21 side, which overlaps with the bellows-shaped portion 55 of the wiring 52. In the example shown in FIG. 4, since the wiring 52 is located on the surface of the wiring board 10, the amplitude S1 is the amplitude of the peaks 53 and valleys 54 of the wiring 52. The amplitude S1 is, for example, 1 μm or more, and more preferably 10 μm or more. By setting the amplitude S1 to 10 μm or more, the wiring 52 becomes more likely to deform in response to the expansion of the substrate 20. The amplitude S1 may also be, for example, 500 μm or less.

The amplitude of the peaks and valleys is calculated, for example, by measuring the distance between adjacent peaks and valleys in the normal direction of the substrate 20 over a certain range in the direction in which the peaks and valleys are aligned, and averaging these distances. The "certain range in the direction in which the peaks and valleys are aligned" is, for example, 10 mm. A non-contact measuring device using a laser microscope or the like may be used as a measuring device for measuring the distance between adjacent peaks and valleys, or a contact measuring device may be used. The distance between adjacent peaks and valleys may also be measured based on an image such as a cross-sectional photograph.

In FIG. 4, the symbol F1 represents the period of the peaks and valleys that appear on the surface of the wiring board 10 on the first surface 21 side, which overlaps with the bellows-shaped portion 55 of the wiring 52. In the example shown in FIG. 4, since the wiring 52 is located on the surface of the wiring board 10, the period F1 is the period of the peaks 53 and valleys 54 of the wiring 52. The period F1 is, for example, 10 μm or more, and more preferably 100 μm or more. The period F1 is, for example, 100 mm or less, and more preferably 10 mm or less. The period F1 of the peaks and valleys is calculated by measuring the spacing between multiple peaks over a certain range in the direction in which the peaks and valleys are arranged, and averaging the measured spacing.

In FIG. 4, the symbol S2 represents the amplitude of the peaks 23 and valleys 24 appearing on the first surface 21 of the substrate 20 in the portion overlapping the bellows-shaped portion 55 of the wiring 52. When the wiring 52 is located on the first surface 21 of the substrate 20 as shown in FIG. 4, the amplitude S2 of the peaks 23 and valleys 24 on the first surface 21 of the substrate 20 is equal to the amplitude S1 of the bellows-shaped portion 55 of the wiring 52.

As shown in FIG. 4, a plurality of peaks 25 and valleys 26 aligned along the direction in which the wiring 52 extends may also appear on the surface of the second surface 22 side of the base material 20 of the wiring board 10. In the example shown in FIG. 3, the peaks 25 on the second surface 22 side appear at positions overlapping the valleys 54 of the bellows-shaped portion 55 of the wiring 52, and the valleys 26 on the second surface 22 side appear at positions overlapping the peaks 53 of the bellows-shaped portion 55 of the wiring 52.

4, the symbol S3 represents the amplitude in the normal direction of the second surface 22 of the substrate 20 of the multiple peaks 25 and valleys 26 arranged along the direction in which the wiring 52 extends on the surface of the wiring board 10 on the second surface 22 side of the substrate 20. The amplitude S3 of the peaks 25 and valleys 26 on the second surface 22 side may be the same as or different from the amplitude S1 of the peaks 53 and valleys 54 on the first surface 21 side. For example, the amplitude S3 of the peaks 25 and valleys 26 on the second surface 22 side may be smaller than the amplitude S1 of the peaks 53 and valleys 54 on the first surface 21 side. For example, the amplitude S3 may be 0.9 times or less, 0.8 times or less, or 0.6 times or less of the amplitude S1. The amplitude S3 may be 0.1 times or more, or 0.2 times or more, of the amplitude S1. Note that "the amplitude S3 of the peaks 25 and valleys 26 on the second surface 22 side is smaller than the amplitude S1 of the peaks 53 and valleys 54 on the first surface 21 side" is a concept that includes cases where the peaks and valleys do not appear on the surface of the wiring board 10 on the second surface 22 side.

In FIG. 4, the symbol F3 represents the period of the multiple peaks 25 and valleys 26 arranged along the direction in which the wiring 52 extends on the surface of the wiring board 10 on the second surface 22 side of the base material 20. The period F3 of the peaks 25 and valleys 26 on the second surface 22 side may be the same as the period F1 of the peaks 53 and valleys 54 on the first surface 21 side, as shown in FIG. 4.

Figure 5 shows another example of a cross-sectional view of the wiring board 10. As shown in Figure 5, the period F3 of the peaks 25 and valleys 26 on the second surface 22 side may be larger than the period F1 of the peaks 53 and valleys 54 on the first surface 21 side. For example, the period F3 may be 1.1 times or more, 1.2 times or more, 1.5 times or more, or 2.0 times or more of the period F1. Note that "the period F3 of the peaks 25 and valleys 26 on the second surface 22 side is larger than the period F1 of the peaks 53 and valleys 54 on the first surface 21 side" is a concept that includes cases where the peaks and valleys do not appear on the surface of the wiring board 10 on the second surface 22 side.

Figure 6 shows another example of a cross-sectional view of the wiring board 10. As shown in Figure 6, the positions of the peaks 25 and valleys 26 on the second surface 22 side may be shifted by J from the positions of the valleys 54 and peaks 53 on the first surface 21 side. The shift amount J is, for example, 0.1 x F1 or more, and may be 0.2 x F1 or more.

Next, the cross-sectional shape of the portion of the wiring board 10 that includes the adjustment mechanism 30 adjacent to the wiring 52 will be described with reference to FIG. 7. FIG. 7 is an enlarged cross-sectional view of the wiring board of FIG. 3 taken along line B-B, which passes through the adjustment mechanism 30.

Like the wiring 52, the adjustment mechanism 30 is also provided on the substrate 20 in a state stretched by tension. For example, in the process of providing the wiring 52 on the substrate 20 in a state stretched by a first stretch amount, the adjustment mechanism 30 is also provided on the substrate 20. In this case, when the tension is removed from the substrate 20 and the substrate 20 contracts, the adjustment mechanism 30 deforms into a bellows shape and has a bellows-shaped portion 35 as shown in FIG. 7. The bellows-shaped portion 35 of the adjustment mechanism 30 includes a plurality of peaks 33 and valleys 34 aligned along the first direction D1.

In FIG. 7, the symbol S4 represents the amplitude of the peaks and valleys that appear on the surface of the wiring board 10 on the first surface 21 side, which overlaps with the bellows-shaped portion 35 of the adjustment mechanism 30. In the example shown in FIG. 7, the adjustment mechanism 30 is located on the surface of the wiring board 10, so the amplitude S4 is the amplitude of the peaks 33 and valleys 34 of the adjustment mechanism 30. The amplitude S4 is, for example, 1 μm or more, and more preferably 10 μm or more. The amplitude S4 may also be, for example, 500 μm or less.

The amplitude S4 in the region of the bellows-shaped portion 35 of the adjustment mechanism 30 may be the same as or different from the amplitude S1 in the region of the bellows-shaped portion 55 of the wiring 52. For example, the amplitude S4 in the region of the adjustment mechanism 30 may be greater than the amplitude S1 in the region of the wiring 52, or may be smaller than the amplitude S1.

In FIG. 7, symbol F4 represents the period of the peaks and valleys that appear on the surface of the wiring board 10 on the first surface 21 side, which overlaps with the bellows-shaped portion 35 of the adjustment mechanism 30. The period F4 in the area of the bellows-shaped portion 35 of the adjustment mechanism 30 may be the same as or different from the period F1 in the area of the bellows-shaped portion 55 of the wiring 52.

In FIG. 7, the symbol S5 represents the amplitude of the peaks 23 and valleys 24 appearing on the first surface 21 of the substrate 20 in the portion overlapping the bellows-shaped portion 35 of the adjustment mechanism 30. The amplitude S5 of the first surface 21 of the substrate 20 in the portion overlapping the adjustment mechanism 30 may be the same as the amplitude S1 of the first surface 21 of the substrate 20 in the portion overlapping the wiring 52, or may be greater than the amplitude S1, or may be smaller than the amplitude S1.

7, the symbols S6 and F6 represent the amplitude and period of the peaks 25 and valleys 26 appearing on the second surface 22 of the substrate 20 in the portion overlapping the bellows-shaped portion 35 of the adjustment mechanism 30. The amplitude S6 of the second surface 22 of the substrate 20 in the portion overlapping the adjustment mechanism 30 may be the same as the amplitude S3 of the second surface 22 of the substrate 20 in the portion overlapping the wiring 52, or may be greater than the amplitude S6, or may be smaller than the amplitude S6. In addition, the period F6 of the second surface 22 of the substrate 20 in the portion overlapping the adjustment mechanism 30 may be the same as the period F3 of the second surface 22 of the substrate 20 in the portion overlapping the wiring 52, or may be greater than the period F6, or may be smaller than the period F6.

Figure 8 shows another example of a cross-sectional view of the wiring board 10. As shown in Figure 8, the adjustment mechanism 30 may include an adhesive layer 32 in contact with the adjustment layer 31. In the example shown in Figure 8, the adhesive layer 32 is located between the adjustment layer 31 and the first surface 21 of the substrate 20. That is, the adjustment layer 31 is adhered to the first surface 21 of the substrate 20 by the adhesive layer 32. In this case, the surface of the adjustment mechanism 30 that includes a resin or elastomer can be achieved by the adhesive layer 32 including a resin or elastomer.

The thickness of the adhesive layer 32 is set so that the adhesive layer 32 is stretchable and the adjustment layer 31 can be attached to the first surface side of the substrate 20. The thickness of the adhesive layer 32 is, for example, in the range of 10 μm or more and 100 μm or less.

The adhesive layer 32 may be a molecular adhesion layer. Note that "molecular adhesion" refers to applying a compound that acts as a molecular adhesive between two adherends, and bonding the two adherends together through chemical bonding.

The molecular adhesive used in the molecular adhesion layer may be any known molecular adhesive, and is appropriately selected depending on the application of the wiring board 10. Examples include silane coupling agents and thiol-based compounds. The thickness of the molecular adhesion layer is, for example, several nm to about 100 nm.

The amplitude S4 in the region of the bellows-shaped portion 35 of the adjustment mechanism 30 including the adjustment layer 31 and the adhesive layer 32 may be smaller than the amplitude S1 in the region of the bellows-shaped portion 55 of the wiring 52. In addition, the period F4 in the region of the bellows-shaped portion 35 of the adjustment mechanism 30 including the adjustment layer 31 and the adhesive layer 32 may be larger than the period F1 in the region of the bellows-shaped portion 55 of the wiring 52.

(Method of Manufacturing Wiring Board)
Next, a method for manufacturing the wiring board 10 will be described with reference to FIGS.

First, as shown in FIG. 9(a), a substrate preparation step is carried out to prepare a substrate 20 having elasticity and including a first surface 21 and a second surface 22. The reference character L0 represents the dimension of the substrate 20 in the first direction D1 when no tension is applied.

Next, as shown in FIG. 9(b), a first elongation step is performed in which a first tension T1 is applied to the substrate 20 in the first direction D1 to elongate the substrate 20 to a dimension L1. The elongation rate of the substrate 20 in the first direction D1 (= (L1-L0) x 100/L0) is, for example, 10% or more and 200% or less. The elongation step may be performed with the substrate 20 in a heated state, or at room temperature. When the substrate 20 is heated, the temperature of the substrate 20 is, for example, 50°C or more and 100°C or less.

Next, as shown in FIG. 9(b), a wiring formation process is carried out to provide wiring 52 on the first surface 21 of the substrate 20 in a state stretched by the first tension T1 in the first stretching process. For example, a conductive paste containing a base material and conductive particles is printed on the first surface 21 of the substrate 20.

In addition, as shown by the dotted line in FIG. 9(b), an adjustment mechanism formation process is carried out in which the adjustment mechanism 30 is provided in an area of the first surface 21 of the substrate 20 in an elongated state that does not overlap with the wiring 52. For example, similar to the case of the wiring 52, the adjustment mechanism 30 is provided on the first surface 21 of the substrate 20 in an elongated state due to the first tension T1. The adjustment mechanism 30 may be provided before the wiring 52 is provided, or may be provided after the wiring 52 is provided.

Then, a first contraction process is carried out to remove the first tension T1 from the substrate 20. As a result, the substrate 20 contracts in the first direction D1 as shown by the arrow C in FIG. 9(c), and the wiring 52 and the adjustment mechanism 30 provided on the substrate 20 also deform. The deformation of the wiring 52 and the adjustment mechanism 30 can occur as the bellows-shaped portion 55 and the bellows-shaped portion 35 as described above. In this way, a wiring board 10 in which a bellows-shaped portion appears can be obtained.

According to this embodiment, the wiring 52 of the wiring board 10 has a bellows-shaped portion 55. Therefore, when the base material 20 of the wiring board 10 expands, the wiring 52 can follow the expansion of the base material 20 by deforming to reduce the undulations of the bellows-shaped portion 55, i.e., by eliminating the bellows shape. Therefore, it is possible to suppress an increase in the overall length of the wiring 52 and a decrease in the cross-sectional area of the wiring 52 due to the expansion of the base material 20. This makes it possible to suppress an increase in the resistance value of the wiring 52 due to the expansion of the wiring board 10. In addition, it is possible to suppress the occurrence of damage such as cracks in the wiring 52.

An example of the effect on the electrical resistance value of the wiring 52 obtained by the bellows-shaped portion 55 of the wiring 52 will be described. Here, the electrical resistance value of the wiring 52 in the first state where tension in the first direction D1 is not applied to the substrate 20 is referred to as the first electrical resistance value. Also, the resistance value of the wiring 52 in the second state where tension is applied to the substrate 20 in the first direction D1 and the substrate 20 is stretched by 30% compared to the first state is referred to as the second electrical resistance value. According to this embodiment, by forming the bellows-shaped portion 55 in the wiring 52, the ratio of the absolute value of the difference between the first electrical resistance value and the second electrical resistance value to the first electrical resistance value can be made 20% or less, more preferably 10% or less, and even more preferably 5% or less.

In addition, according to this embodiment, the wiring board 10 has an adjustment mechanism 30. Therefore, it is possible to suppress the concentration of stress on the wiring 52 due to the difference between the elastic modulus of the base material 20 and the elastic modulus of the wiring 52. This makes it possible to suppress deformation such as curvature and bending occurring in the wiring board 10 from becoming large locally. This makes it possible to suppress the occurrence of damage such as cracks in the wiring 52. In addition, it is possible to suppress an increase in the electrical resistance value of the wiring 52 when the wiring board 10 is repeatedly expanded and contracted.

In addition, according to this embodiment, the adjustment mechanism 30 is arranged so as not to overlap with the wiring 52. For example, the adjustment mechanism 30 is provided with a gap Z1 between it and the wiring 52, and therefore the adjustment mechanism 30 has a side edge 30e extending along the wiring 52. Since the adjustment mechanism 30 does not overlap with the wiring 52, it is possible to suppress deterioration of the electrical characteristics of the wiring 52 caused by the adjustment mechanism 30 contacting the wiring 52. This makes it possible to prevent, for example, an increase in the electrical resistance value of the wiring 52 before and after the wiring board 10 is repeatedly expanded and contracted. In addition, by setting the gap Z1 between the wiring 52 and the adjustment mechanism 30 to 10 μm or less, the periodicity of the bellows-shaped portion 35 appearing in the portion of the base material 20 overlapping with the adjustment mechanism 30 can affect the periodicity of the bellows-shaped portion 35 appearing in the portion of the base material 20 overlapping with the wiring 52.

The applications of the wiring board 10 include the health care field, the medical field, the nursing field, the electronics field, the sports and fitness field, the beauty field, the mobility field, the livestock and pet field, the amusement field, the fashion and apparel field, the security field, the military field, the distribution field, the education field, the building materials, furniture and decoration field, the environmental energy field, the agriculture, forestry and fisheries field, and the robot field. For example, a product to be attached to a part of the body such as a human arm is constructed using the wiring board 10 according to this embodiment. Since the wiring board 10 can be stretched, for example, by attaching the wiring board 10 to the body in a stretched state, the wiring board 10 can be made to adhere more closely to the part of the body. Therefore, a good wearing feeling can be realized. In addition, since the electrical resistance value of the wiring 52 can be suppressed from decreasing when the wiring board 10 is stretched, the wiring board 10 can achieve good electrical characteristics. In addition, since the wiring board 10 can be stretched, it is possible to install or incorporate it along a curved surface or a three-dimensional shape, not limited to a living body such as a human. Examples of such products include vital sensors, masks, hearing aids, toothbrushes, bandages, compresses, contact lenses, artificial hands, artificial legs, artificial eyes, catheters, gauze, medical packs, bandages, disposable bioelectrodes, diapers, home appliances, sportswear, wristbands, headbands, gloves, swimsuits, supporters, balls, rackets, grips, medical beauty masks, electrical stimulation diet products, pocket warmers, car interiors, seats, instrument panels, strollers, drones, wheelchairs, tires, collars, leashes, haptic devices, placemats, hats, clothes, glasses, shoes, insoles, socks, stockings, innerwear, scarves, earmuffs, bags, accessories, rings, false nails, watches, personal ID recognition devices, helmets, packages, IC tags, plastic bottles, stationery, books, carpets, sofas, bedding, lighting, doorknobs, vases, beds, mattresses, cushions, wireless power supply antennas, batteries, vinyl greenhouses, robot hands, and robot exteriors.

Note that various modifications can be made to the above-described embodiment. Below, modified examples will be described with reference to the drawings as necessary. In the following description and the drawings used in the following description, parts that can be configured similarly to the above-described embodiment will be labeled with the same reference numerals as those used for the corresponding parts in the above-described embodiment, and duplicated descriptions will be omitted. Also, if it is clear that the effects obtained in the above-described embodiment can also be obtained in the modified example, the description may be omitted.

(First Modification)
In this modified example, an example will be described in which the adjustment mechanism 30 also functions as a stopper that prevents the substrate 20 from being excessively stretched and causing defects such as breakage of components such as the wiring 52.

Figure 10 is a cross-sectional view of the wiring board 10 along line B-B in Figure 1 passing through the adjustment mechanism 30, and corresponds to Figure 7 in the above-mentioned embodiment. In this modified example, the period F4 of the peaks and valleys in the region of the bellows-shaped portion 35 of the adjustment mechanism 30 is larger than the period F1 of the peaks and valleys in the region of the bellows-shaped portion 55 of the wiring 52 shown in Figure 4 and the like. For example, the period F4 may be 1.1 times or more, 1.2 times or more, 1.5 times or more, or 2.0 times or more of the period F1. In addition, the amplitude S4 of the peaks and valleys in the region of the bellows-shaped portion 35 of the adjustment mechanism 30 is smaller than the amplitude S1 of the peaks and valleys in the region of the bellows-shaped portion 55 of the wiring 52 shown in Figure 4 and the like. For example, the amplitude S4 may be 0.9 times or less, 0.8 times or less, or 0.6 times or less of the amplitude S1. Furthermore, the amplitude S4 may be 0.1 times or more, or 0.2 times or more, of the amplitude S1.

(Method of Manufacturing Wiring Board)
Next, a method for manufacturing the wiring board 10 will be described with reference to FIGS. 11(a) to 11(c) and 12(a) to 12(c).

First, as shown in FIG. 11(a), a substrate preparation process is performed to prepare the substrate 20. Then, as shown in FIG. 11(b), a first extension process is performed to apply a first tension T1 to the substrate 20 in a first direction D1 to extend the substrate 20 to a dimension L1. Then, as shown in FIG. 11(b), a wiring formation process is performed to provide wiring 52 on the first surface 21 of the substrate 20 in a state extended by the first tension T1 in the first extension process. After that, a first contraction process is performed to remove the first tension T1 from the substrate 20.

Next, as shown in FIG. 12(a), a second extension step is performed in which a second tension T2 is applied to the substrate 20 in the first direction D1 to extend the substrate 20 to a dimension L2. The second tension T2 is smaller than the first tension T1 in the above-mentioned first extension step. Therefore, the extension rate of the substrate 20 in the second extension step (=(L2-L0)×100/L0) is smaller than the extension rate of the substrate 20 in the first extension step. Therefore, in the second extension step, the bellows-shaped portion 55 of the wiring 52 is not completely eliminated. The extension rate of the substrate 20 in the second extension step may be 0.9 times or less, 0.8 times or less, or 0.6 times or less than that of the substrate 20 in the first extension step.

Next, as shown by the dotted line in FIG. 12(b), an adjustment mechanism formation process is carried out to provide an adjustment mechanism 30 in an area of the first surface 21 of the substrate 20 that does not overlap with the wiring 52 when the substrate 20 is stretched by the second tension T2 in the second stretching process.

Then, a second contraction process is carried out to remove the second tension T2 from the substrate 20. As a result, as shown by the arrow C in FIG. 12(c), the substrate 20 contracts in the first direction D1, and the adjustment mechanism 30 provided on the substrate 20 also deforms. The deformation of the adjustment mechanism 30 can occur as the bellows-shaped portion 35 as described above. In this manner, a wiring board 10 including the substrate 20, the wiring 52, and the adjustment mechanism 30 can be obtained.

Next, the function of the wiring board 10 will be described with reference to FIG. 13. FIG. 13 is a diagram showing an example of how the tension and electrical resistance of the wiring 52 change when the wiring board 10 is stretched. In FIG. 13, the horizontal axis represents the amount of stretch E of the wiring board 10. The vertical axis on the left represents the tension T applied to the wiring board 10. The vertical axis on the right represents the electrical resistance R between two points on the wiring 52 that are aligned in the first direction D1.

In FIG. 13, the line marked with the symbol C1 is drawn by connecting the measurement points obtained by measuring the electrical resistance R between two points on the wiring 52 while stretching the wiring board 10 in the first direction D1. The line marked with the symbol C2 is drawn by connecting the measurement points obtained by measuring the tension T applied to the wiring board 10 while stretching the wiring board 10 in the first direction D1. As a measuring device for measuring the tension T, a device capable of measuring the elongation rate and the elastic modulus in accordance with "JIS L 1096 Testing Method for Woven and Knit Fabrics" can be used, for example, a Tensilon universal material testing machine manufactured by A&D Co., Ltd. can be used. As a measuring device for measuring the electrical resistance R, for example, a KEITHLEY 2000 digital multimeter manufactured by Keithley Co., Ltd. can be used. The distance in the first direction D1 between two points on the wiring 52 is 10 mm or more and 200 mm or less, for example, 30 mm.

As shown in FIG. 13, when the extension amount E of the substrate 20 in the first direction D1 is the first extension amount E1, the electrical resistance R indicates a first turning point P1 at which the increase in electrical resistance E per unit extension amount changes. The first turning point P1 appears, for example, when the bellows-shaped portion 55 of the wiring 52 is eliminated.

In the example of FIG. 13, the first turning point P1 is defined as a point having an elongation amount at the point where the straight lines M1 and M2 intersect. The straight line M1 is a straight line that is tangent to the line C1 at a position where the elongation amount E is zero. The slope of the straight line M1 represents the increase in the electrical resistance R per unit elongation amount (hereinafter also referred to as the first electrical resistance increase rate) when the elongation amount E of the wiring board 10 in the first direction D1 is smaller than the first elongation amount E1. The straight line M2 is a straight line that approximates the line C1 at a position where the slope of the line C1 is significantly larger than the slope of the straight line M1. The slope of the straight line M2 represents the increase in the electrical resistance R per unit elongation amount (hereinafter also referred to as the second electrical resistance increase rate) when the elongation amount E of the wiring board 10 in the first direction D1 is larger than the first elongation amount E1.

The second electrical resistance increase rate is preferably at least twice as high as the first electrical resistance increase rate, and may be at least three times, or may be at least four times as high. Although not shown, the first turning point P1 may be defined as the point at which the slope of line C1 is twice that of line M1.

As shown in FIG. 13, when the extension amount E of the substrate 20 in the first direction D1 is the second extension amount E2, the tension T indicates a second turning point P2 at which the increase in the tension T per unit extension amount changes. The second turning point P2 appears, for example, when the bellows-shaped portion 35 of the adjustment mechanism 30 is released.

In the example of FIG. 13, the second turning point P2 is defined as a point having an elongation amount at the point where the straight lines N1 and N2 intersect. The straight line N1 is a straight line that is tangent to the line C2 at a position where the elongation amount E is zero. The inclination of the straight line N1 represents the increase in tension T per unit elongation amount (hereinafter also referred to as the first tension increase rate) when the elongation amount E of the wiring board 10 in the first direction D1 is smaller than the second elongation amount E2. The straight line N2 is a straight line that approximates the line C2 at a position where the inclination of the line C2 is significantly larger than the inclination of the straight line N1. The inclination of the straight line N2 represents the increase in tension T per unit elongation amount (hereinafter also referred to as the second tension increase rate) when the elongation amount E of the wiring board 10 in the first direction D1 is larger than the second elongation amount E2.

The second tension increase rate is preferably at least twice the first tension increase rate, and may be at least three times, or may be at least four times. Although not shown, the second turning point P2 may be defined as the point at which the slope of line C2 is twice that of line N1.

In this embodiment, as described above, the extension rate of the substrate 20 when the adjustment mechanism 30 is provided is smaller than the extension rate of the substrate 20 when the wiring 52 is provided. Therefore, when the wiring board 10 including the substrate 20 is extended, the bellows-shaped portion 35 of the adjustment mechanism 30 is eliminated before the bellows-shaped portion 55 of the wiring 52 is eliminated. Therefore, as shown in FIG. 13, the second turning point P2 can be made to appear on the wiring board 10 when the second extension amount E2 is smaller than the first extension amount E1.

Figure 14 is an example of a cross-sectional view of the wiring board 10 when it is stretched to the second stretch amount E2. In the example shown in Figure 14, the bellows-shaped portion 35 of the adjustment mechanism 30 is eliminated, but the bellows-shaped portion 55 of the wiring 52 is not eliminated. In order to further stretch the wiring board 10 from the state shown in Figure 14, it is necessary to deform the adjustment mechanism 30 itself in the first direction D1. Therefore, after the second turning point P2 appears, the inclination of the line C2 increases significantly as shown in Figure 13, making it difficult for the wiring board 10 to stretch. This makes it possible to prevent the wiring board 10 from being stretched excessively. This makes it possible to prevent defects such as breakage from occurring in components such as the wiring 52 of the wiring board 10.

The first extension amount E1 is preferably 1.1 times or more than the second extension amount E2, and may be 1.2 times or more, 1.5 times or more, or 2.0 times or more. By making the first extension amount E1 1.1 times or more than the second extension amount E2, it becomes easier to stop the extension of the wiring board 10 before the extension of the wiring board 10 reaches the first extension amount E1. Furthermore, the first extension amount E1 may be 5 times or less than the second extension amount E2. In other words, the second extension amount E2 may be 1/5 or more of the first extension amount. It is possible to ensure the extension amount required when attaching the wiring board 10 to a part of the body such as a person's arm.

In this way, according to this embodiment, the wiring board 10 can be stretched in the first direction D1 during use while preventing defects such as breakage of the wiring 52. Therefore, the wiring board 10 can be used in applications that require stretchability in various directions.

Also, as in the case of the above-described embodiment, in this modified example, the adjustment mechanism 30 can also function to suppress the concentration of stress on the wiring 52. This can suppress deformation such as curvature and bending occurring in the wiring board 10 from becoming large locally. This can suppress the occurrence of damage such as cracks in the wiring 52. In addition, it can suppress an increase in the electrical resistance value of the wiring 52 when the wiring board 10 is repeatedly expanded and contracted.

In addition, in this modified example, the adjustment mechanism 30 is also provided with a gap Z1 between it and the wiring 52. This makes it possible to suppress deterioration of the electrical characteristics of the wiring 52 caused by the adjustment mechanism 30 coming into contact with the wiring 52. This makes it possible to prevent, for example, an increase in the electrical resistance of the wiring 52 before and after the wiring board 10 is repeatedly expanded and contracted.

(Second Modification)
In the above embodiment, an example in which the wiring 52 is provided on the first surface 21 of the base material 20 has been described, but the present invention is not limited to this. In the present modified example, an example in which the wiring 52 is supported by a supporting substrate will be described.

Figure 15 is a cross-sectional view of a portion of wiring board 10 according to the second modified example, including wiring 52, and corresponds to Figure 4 in the above-described embodiment. Also, Figure 16 is a cross-sectional view of a portion of wiring board 10 according to the second modified example, including adjustment mechanism 30, and corresponds to Figure 7 in the above-described embodiment. Wiring board 10 includes at least base material 20, support substrate 40, wiring 52, and adjustment mechanism 30.

[Support substrate]
The support substrate 40 is a member configured to have lower elasticity than the base material 20. The support substrate 40 includes a second surface 42 located on the base material 20 side and a first surface 41 located on the opposite side of the second surface 42. In the example shown in FIG. 15, the support substrate 40 supports the wiring 52 on the first surface 41 side. The support substrate 40 is also bonded to the first surface 21 of the base material 20 on the second surface 42 side. For example, an adhesive layer 60 containing an adhesive may be provided between the base material 20 and the support substrate 40. For example, an acrylic adhesive, a silicone adhesive, or the like can be used as a material constituting the adhesive layer 60. The thickness of the adhesive layer 60 is, for example, 5 μm or more and 200 μm or less.

In this modified example, as in the above-described embodiment, the adjustment mechanism 30 is arranged so as not to contact the wiring 52. For example, as shown in FIG. 16, the adjustment mechanism 30 is provided in a portion of the first surface 41 of the support substrate 40 that does not overlap with the wiring 52.

Figure 17 is an enlarged cross-sectional view of the wiring board 10 of Figure 15. In this modification, when tension is removed from the base material 20 bonded to the support substrate 40 and the base material 20 contracts, peaks and valleys similar to the peaks 53 and valleys 54 of the wiring 52 also appear on the support substrate 40. The characteristics and dimensions of the support substrate 40 are set so that such peaks and valleys are easily formed. For example, the support substrate 40 has an elastic modulus greater than the first elastic modulus of the base material 20. In the following description, the elastic modulus of the support substrate 40 is also referred to as the third elastic modulus.

Although not shown, the support substrate 40 may support the wiring 52 on the second surface 42 side. In this case, the adjustment mechanism 30 may also be provided on a portion of the second surface 42 of the support substrate 40 that does not overlap with the wiring 52.

The third elastic modulus of the support substrate 40 is, for example, 100 MPa or more, more preferably 1 GPa or more. The third elastic modulus of the support substrate 40 may be 100 times or more and 50,000 times or less, and preferably 1,000 times or more and 10,000 times or less, of the first elastic modulus of the base material 20. By setting the third elastic modulus of the support substrate 40 in this manner, it is possible to prevent the period F1 of the peaks 53 and the valleys 54 from becoming too small. It is also possible to prevent local bending in the peaks 53 and the valleys 54.
If the elastic modulus of the support substrate 40 is too low, the support substrate 40 is likely to deform during the process of forming the wiring 52, which makes it difficult to align the wiring 52 with respect to the support substrate 40. If the elastic modulus of the support substrate 40 is too high, it becomes difficult for the base material 20 to restore its original shape when relaxed, and the base material 20 is likely to crack or break.

The thickness of the support substrate 40 is, for example, 500 nm or more and 10 μm or less, and more preferably 1 μm or more and 5 μm or less. If the thickness of the support substrate 40 is too small, it becomes difficult to handle the support substrate 40 during the manufacturing process of the support substrate 40 and during the process of forming components such as the wiring 52 on the support substrate 40. If the thickness of the support substrate 40 is too large, it becomes difficult for the base material 20 to restore its original shape when relaxed, and the desired expansion and contraction of the base material 20 cannot be obtained.

Materials that can be used to form the support substrate 40 include, for example, polyethylene naphthalate, polyimide, polyethylene terephthalate, polycarbonate, acrylic resin, etc. Among these, polyethylene naphthalate or polyimide, which have good durability and heat resistance, can be preferably used.

The third elastic modulus of the support substrate 40 may be 100 times or less than the first elastic modulus of the base material 20. The method for calculating the third elastic modulus of the support substrate 40 is the same as that for the base material 20 or the adjustment layer 31.

(Method of Manufacturing Wiring Board)
Next, a method for manufacturing the wiring board 10 according to this modified example will be described with reference to FIGS.

First, the support substrate 40 is prepared. Next, wiring 52 is provided on the first surface 41 of the support substrate 40. For example, a metal layer such as a copper layer is first formed on the first surface 41 of the support substrate 40 by a deposition method or the like. Next, the metal layer is processed using a photolithography method and an etching method. This makes it possible to obtain wiring 52 on the first surface 41.

Next, as shown in FIG. 18(b), a first extension step is performed in which a first tension T1 is applied to the substrate 20 in the first direction D1 to extend the substrate 20 to a dimension L1. Then, a wiring formation step is performed in which wiring 52 is provided on the first surface 21 of the substrate 20 in a state extended by the first tension T1 in the first extension step. In the wiring formation step of this modified example, as shown in FIG. 18(b), the second surface 42 of the support substrate 40, on which wiring 52 is provided, is bonded to the first surface 21 of the substrate 20. At this time, an adhesive layer 60 may be provided between the substrate 20 and the support substrate 40.

Then, a first contraction process is carried out to remove the first tension T1 from the substrate 20. As a result, as shown by the arrow C in FIG. 18(c), the substrate 20 contracts in the first direction D1, and the support substrate 40 and wiring 52 provided on the substrate 20 also deform. The deformation of the support substrate 40 and wiring 52 can occur as a bellows-shaped portion as described above.

In this modification, the timing for performing the adjustment mechanism forming step of providing the adjustment mechanism 30 on the support substrate 40 is arbitrary.
For example, the adjustment mechanism 30 may be provided on the support substrate 40 before it is bonded to the base material 20. In this case, the adjustment mechanism 30 may be provided on the support substrate 40 before the wiring 52 is provided, or the adjustment mechanism 30 may be provided on the support substrate 40 after the wiring 52 is provided.
Also, as in the case of the first modified example described above, an adjustment mechanism 30 may be provided on a support substrate 40 joined to a substrate 20 in a state in which the substrate 20 is elongated at an elongation rate smaller than the elongation rate of the substrate 20 in the first elongation step.

Even in this modified example, the adjustment mechanism 30 can function to suppress the concentration of stress on the wiring 52. This can suppress deformation such as curvature and bending that occurs in the wiring board 10 from becoming large locally. This can suppress the occurrence of damage such as cracks in the wiring 52. In addition, it can suppress an increase in the electrical resistance value of the wiring 52 when the wiring board 10 is repeatedly expanded and contracted.

In addition, in this modified example, the adjustment mechanism 30 is also provided with a gap Z1 between it and the wiring 52. This makes it possible to suppress deterioration of the electrical characteristics of the wiring 52 caused by the adjustment mechanism 30 coming into contact with the wiring 52. This makes it possible to prevent, for example, an increase in the electrical resistance of the wiring 52 before and after the wiring board 10 is repeatedly expanded and contracted.

(Third Modification)
In the above-mentioned second modified example, an example has been shown in which the support substrate 40 is bonded to the base material 20 via the adhesive layer 60. However, this is not limited thereto, and the support substrate 40 may be bonded to the base material 20 by a method of molecularly modifying a non-adhesive surface and performing molecular adhesive bonding. In this case, as shown in FIG. 19, an adhesive layer may not be provided between the base material 20 and the support substrate 40.

(Fourth Modification)
In the above-described second and third modified examples, an example has been shown in which the wiring 52 and the adjustment mechanism 30 are provided on the first surface 41 side of the support substrate 40. However, this is not limited to this, and the wiring 52 and the adjustment mechanism 30 may be provided on the second surface 42 side of the support substrate 40 as shown in FIG.

(Fifth Modification)
In the above-described embodiment, an example has been shown in which the adjustment mechanism 30 is disposed so as not to overlap the wiring 52. However, this is not limited thereto, and as shown in FIG. 21, the adjustment mechanism 30 may include an overlapping portion 37 that overlaps the wiring 52. In this case, it is preferable that the ratio of the area of the portion of the wiring 52 that does not overlap with the adjustment mechanism 30 to the entire area of the wiring 52 (hereinafter, non-overlapping rate) is greater than the ratio of the area of the portion of the wiring 52 that overlaps with the adjustment mechanism 30 to the entire area of the wiring 52 (overlapping rate). The non-overlapping rate is, for example, two or more times the overlapping rate, and may be three or more times, four or more times, or five or more times. This makes it possible to suppress deterioration of the electrical characteristics of the wiring 52 caused by the adjustment mechanism 30 contacting the wiring 52.

As shown in FIG. 21, the overlapping portions 37 of the adjustment mechanism 30 may be arranged at intervals along the direction in which the wiring 52 extends. In this case, when the base material 20 in a stretched state is relaxed, bellows-shaped portions 55 corresponding to the arrangement period of the overlapping portions 37 are likely to be generated in the wiring 52. In other words, the period of the bellows-shaped portions 55 can be controlled by the overlapping portions 37.

(Sixth Modification)
Fig. 22 is a plan view showing the wiring board 10 according to this modified example. Fig. 23 is a cross-sectional view taken along line CC of the wiring board 10 in Fig. 22. As shown in Figs. 22 and 23, the wiring board 10 may include an electronic component 51 electrically connected to wiring 52. In the example shown in Figs. 22 and 23, the electronic component 51 is located on the first surface 41 side of the support substrate 40. Alternatively, the wiring board 10 may be configured such that the electronic component 51 is not mounted, but the electronic component 51 is electrically connected to the wiring 52.

As shown in FIG. 22, the adjustment mechanism 30 may be arranged so as not to overlap the electronic component 51. Although not shown, a portion of the adjustment mechanism 30 may overlap the electronic component 51.

The electronic component 51 may have an electrode connected to the wiring 52. In this case, the wiring board 10 has a connection portion that contacts the electrode of the electronic component 51 and is electrically connected to the wiring 52. The connection portion is, for example, a pad.

The electronic component 51 may not have an electrode connected to the wiring 52. For example, the electronic component 51 may include a member integral with at least one of the multiple components of the wiring board 10. Examples of such electronic components 51 include those including a conductive layer integral with the conductive layer constituting the wiring 52 of the wiring board 10, and those including a conductive layer located in a layer different from the conductive layer constituting the wiring 52. For example, the electronic component 51 may be a pad formed by a conductive layer having a width wider in a planar view than the conductive layer constituting the wiring 52. A probe for inspection, a terminal for software rewriting, etc. are connected to the pad. The electronic component 51 may also be a wiring pattern formed by a conductive layer extending in a spiral shape in a planar view. In this way, a part in which a conductive layer is patterned and a predetermined function is given can also be the electronic component 51.

The electronic component 51 may be an active component, a passive component, or a mechanical component. Examples of the electronic component 51 include transistors, LSIs (Large-Scale Integration), MEMS (Micro Electro Mechanical Systems), relays, light-emitting elements such as LEDs, OLEDs, and LCDs, sensors, sound-generating components such as buzzers, vibration components that generate vibrations, cooling and heating components such as Peltier elements and heating wires that control cooling and heating, resistors, capacitors, inductors, piezoelectric elements, switches, and connectors. Of the above examples of the electronic component 51, sensors are preferably used. Examples of sensors include temperature sensors, pressure sensors, optical sensors, photoelectric sensors, proximity sensors, shear force sensors, biosensors, laser sensors, microwave sensors, humidity sensors, strain sensors, gyro sensors, acceleration sensors, displacement sensors, magnetic sensors, gas sensors, GPS sensors, ultrasonic sensors, odor sensors, brainwave sensors, current sensors, vibration sensors, pulse wave sensors, electrocardiogram sensors, and luminosity sensors. Of these sensors, biosensors are particularly preferred. Biometric sensors can measure biometric information such as heart rate, pulse, electrocardiogram, blood pressure, body temperature, and blood oxygen concentration.

Next, the uses of the electronic component 51 that does not have electrodes will be described. For example, the pads described above can function as parts to which probes for testing or terminals for software rewriting are connected. In addition, the wiring pattern formed by extending in a spiral shape can function as an antenna, etc.

Although several variations on the above embodiment have been described, it is of course possible to combine multiple variations as appropriate.

Next, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to the description of the following examples as long as it does not deviate from the gist of the invention.

[Example 1]
(Preparation of elastic substrate)
An adhesive sheet functioning as the adhesive layer 60 was placed on the support. As the adhesive sheet, an adhesive sheet 8146 manufactured by 3M was used. Then, two-liquid addition condensation polydimethylsiloxane (PDMS) was applied onto the adhesive sheet, and the PDMS was cured. This resulted in the formation of a substrate 20 on the adhesive sheet. The thickness of the substrate 20 after curing was 900 μm. Then, a part of the first laminate including the substrate 20 and the adhesive layer 60 was cut out, and the substrate 20 from which the adhesive layer 60 had been removed was used as a sample to measure the elastic modulus of the substrate 20 by a tensile test in accordance with JIS K6251. As a result, the elastic modulus of the substrate 20 was 0.05 MPa. In addition, the cross-sectional area of the substrate 20 was 0.45×10 ⁻⁶ m ² .

(Preparation of supporting substrate, wiring and adjustment layer)
A polyethylene naphthalate (PEN) film having a thickness of 2.5 μm was prepared as the support substrate 40. Then, a conductive paste was printed in a predetermined pattern on the first surface 41 of the support substrate 40 to form the wiring 52. Screen printing was used as the printing method. The conductive paste used contained silver conductive particles. The wiring 52 had a width of 200 μm and a length of 40 mm. In addition, a part of the support substrate 40 was taken as a sample, and the elastic modulus of the support substrate 40 was measured by a tensile test in accordance with ASTM D882. As a result, the elastic modulus of the support substrate was 2.2 GPa.

Next, an adjustment layer 31 was formed by printing urethane resin on the area of the first surface 41 of the support substrate 40 that did not overlap with the wiring 52. Screen printing was used as the printing method. The adjustment layer 31 had a thickness of 30 μm. Next, a portion of the adjustment layer 31 was taken as a sample, and the elastic modulus of the adjustment layer 31 was measured by a tensile test in accordance with JIS K6251. As a result, the elastic modulus of the adjustment layer 31 was 35 MPa.

The relationship in magnitude between the elastic modulus of the base material 20, the support substrate 40, the wiring 52, and the adjustment layer 31 is as follows.
Base material 20 < adjustment layer 31 < wiring 52 < support substrate 40

(Joining of Base Material and Support Substrate)
A tension was applied to the base material 20 on which the adhesive layer 60 was formed, and in a state in which the base material 20 and the adhesive layer 60 were stretched by 50% in the first direction D1, the support substrate 40 on which the wiring 52 and the adjustment layer 31 were provided was joined to the adhesive layer 60. The resistance of the wiring 52 in this state was 35 Ω.

Then, the tension was removed to release the extension, and the substrate 20 was allowed to shrink. In this manner, the wiring board 10 was produced. In the obtained wiring board 10, a bellows-shaped portion including multiple peaks appeared on the surface of the support substrate 40 and the wiring 52 provided on the support substrate 40. When the period was measured over five periods of the multiple peaks, the average period was 540 μm. The minimum value of the radius of curvature in the bellows-shaped portion was 43 μm. In addition, the resistance of the wiring was 42 Ω, and the difference from the resistance before shrinkage was small.

Then, the wiring board 10 was stretched by 30% and then released from the stretched state, repeatedly performed 10,000 times. The resistance of the wiring measured after that was 71 Ω, which was 1.7 times higher than before the 10,000-time stretch test.

[Comparative Example 1]
Wiring board 10 was fabricated in the same manner as in Example 1, except that adjustment layer 31 containing urethane resin was also formed in an area not overlapping wiring 52 on first surface 41 side of support substrate 40. Resistance of wiring 52 in this state was 35 Ω.

Then, the tension was removed to release the extension, and the substrate 20 was allowed to shrink. In this manner, the wiring board 10 was produced. In the obtained wiring board 10, a bellows-shaped portion including multiple peaks appeared on the surface of the support substrate 40 and the wiring 52 provided on the support substrate 40. When the period was measured over five periods of the multiple peaks, the average period was 620 μm. The minimum value of the radius of curvature in the bellows-shaped portion was 45 μm. In addition, the resistance of the wiring was 39 Ω, and the difference from the resistance before shrinkage was small.

Then, the wiring board 10 was stretched by 30% and released from the stretched state, repeatedly performed 10,000 times. The resistance of the wiring measured after that was 220 Ω, which was 5.7 times higher than before the 10,000-time stretch test.

[Comparative Example 2]
Except for not forming the adjustment layer 31 on the first surface 41 of the support substrate 40, the wiring substrate 10 was fabricated in the same manner as in Example 1. The resistance of the wiring 52 in this state was 47 Ω.

Then, the tension was removed to release the extension, and the substrate 20 was allowed to shrink. In this manner, the wiring board 10 was produced. In the obtained wiring board 10, a bellows-shaped portion including multiple peaks appeared on the surface of the support substrate 40 and the wiring 52 provided on the support substrate 40. When the period of the multiple peaks was measured over five periods, the average period was 420 μm, and the standard deviation of the period was 67 μm. Furthermore, the minimum value of the radius of curvature of the bellows-shaped portion was 2 μm. Non-uniform wrinkles and bent wiring were confirmed in the bellows-shaped portion. Furthermore, the resistance of the wiring was 81 Ω, 1.7 times that before shrinkage.

REFERENCE SIGNS LIST 10 Wiring board 20 Base material 21 First surface 22 Second surface 23 Peak 24 Valley 25 Peak 26 Valley 30 Adjustment mechanism 31 Adjustment layer 32 Adhesive layer 33 Peak 34 Valley 37 Overlapping portion 40 Support substrate 41 First surface 42 Second surface 51 Electronic component 52 Wiring 53 Peak 54 Valley

Claims (29)

A wiring board,
A base material having elasticity, the base material including a first surface and a second surface located opposite the first surface;
a wiring located on the first surface side of the base material and having a bellows-shaped portion including a plurality of peaks and valleys aligned along a first direction that is one of the in-plane directions of the first surface of the base material;
an adjustment mechanism that is located on the first surface side of the base material, has a side edge that extends in the first direction with a gap between it and the wiring when viewed along a normal direction of the first surface, and includes a resin or an elastomer on a surface thereof;
a ratio of an area of the adjustment mechanism to an area of a portion of the wiring board on which the wiring is not provided is 50% or more;
When the tension applied to the wiring board and the electrical resistance of the wiring are measured while the wiring board is stretched in the first direction, the electrical resistance shows a first turning point where the increase in the electrical resistance per unit elongation amount changes when the elongation amount of the wiring board in the first direction is a first elongation amount, and the tension shows a second turning point where the increase in the tension per unit elongation amount changes when the elongation amount of the wiring board in the first direction is a second elongation amount that is smaller than the first elongation amount . The wiring board according to claim 1, wherein the adjustment mechanism is positioned so as to sandwich the wiring in a second direction perpendicular to the first direction. The wiring board according to claim 1 or 2, wherein the adjustment mechanism includes an adjustment layer having a lower elastic modulus than the wiring. The wiring board according to any one of claims 1 to 3, wherein the adjustment mechanism includes an adjustment layer having a bending stiffness or elastic modulus higher than that of the substrate. The wiring board according to any one of claims 1 to 4, wherein the wiring includes a base material and conductive particles. The wiring board according to any one of claims 1 to 5, wherein the adjustment mechanism has a dimension in a second direction perpendicular to the first direction that is equal to or greater than the width of the wiring. The wiring board according to claim 6, wherein the adjustment mechanism has a dimension in a second direction perpendicular to the first direction that is at least twice the width of the wiring. The wiring board according to any one of claims 1 to 7, wherein the distance between the side edge of the adjustment mechanism and the wiring is equal to or less than the width of the wiring. The wiring board according to any one of claims 1 to 8, wherein the distance between the side edge of the adjustment mechanism and the wiring is 100 μm or less. The wiring board according to any one of claims 1 to 9, wherein the adjustment mechanism has a bellows-shaped portion including a plurality of peaks and valleys aligned along the first direction. A wiring board,
A base material having elasticity, the base material including a first surface and a second surface located opposite the first surface;
a wiring located on the first surface side of the base material and having a bellows-shaped portion including a plurality of peaks and valleys aligned along a first direction that is one of the in-plane directions of the first surface of the base material;
an adjustment mechanism that is located on the first surface side of the base material, has a side edge that extends in the first direction with a gap between it and the wiring when viewed along a normal direction of the first surface, and includes a resin or an elastomer on a surface thereof;
a ratio of an area of the adjustment mechanism to an area of a portion of the wiring board on which the wiring is not provided is 50% or more;
A wiring board, wherein the amplitude of peaks and valleys appearing on a portion of the surface of the wiring board on the second surface side of the base material that overlaps the bellows-shaped portion of the wiring is different from the amplitude of peaks and valleys appearing on a portion of the surface of the wiring board on the first surface side of the base material that overlaps the bellows-shaped portion of the wiring . The wiring board according to claim 11, wherein the amplitude of the peaks and valleys appearing in the portion of the surface of the wiring board on the second surface side of the base material that overlaps the bellows-shaped portion of the wiring is smaller than the amplitude of the peaks and valleys appearing in the portion of the surface of the wiring board on the first surface side of the base material that overlaps the bellows-shaped portion of the wiring. A wiring board,
A base material having elasticity, the base material including a first surface and a second surface located opposite the first surface;
a wiring located on the first surface side of the base material and having a bellows-shaped portion including a plurality of peaks and valleys aligned along a first direction that is one of the in-plane directions of the first surface of the base material;
an adjustment mechanism that is located on the first surface side of the base material, has a side edge that extends in the first direction with a gap between it and the wiring when viewed along a normal direction of the first surface, and includes a resin or an elastomer on a surface thereof;
a ratio of an area of the adjustment mechanism to an area of a portion of the wiring board on which the wiring is not provided is 50% or more;
A wiring board, wherein the periodicity of peaks and valleys appearing in a portion of the surface of the wiring board on the second surface side of the base material that overlaps the bellows-shaped portion of the wiring is different from the periodicity of peaks and valleys appearing in a portion of the surface of the wiring board on the first surface side of the base material that overlaps the bellows-shaped portion of the wiring . The wiring board according to claim 13, wherein the periodicity of the peaks and valleys appearing in the portion of the surface of the wiring board on the second side of the base material that overlaps the bellows-shaped portion of the wiring is greater than the periodicity of the peaks and valleys appearing in the portion of the surface of the wiring board on the first side of the base material that overlaps the bellows-shaped portion of the wiring. A wiring board,
A base material having elasticity, the base material including a first surface and a second surface located opposite the first surface;
a wiring located on the first surface side of the base material and having a bellows-shaped portion including a plurality of peaks and valleys aligned along a first direction that is one of the in-plane directions of the first surface of the base material;
an adjustment mechanism that is located on the first surface side of the base material, has a side edge that extends in the first direction with a gap between it and the wiring when viewed along a normal direction of the first surface, and includes a resin or an elastomer on a surface thereof;
a ratio of an area of the adjustment mechanism to an area of a portion of the wiring board on which the wiring is not provided is 50% or more;
a wiring board, wherein the positions of peaks and valleys appearing in a portion of the surface of the wiring board on the second surface side of the base material that overlaps the bellows-shaped portion of the wiring are shifted from the positions of peaks and valleys appearing in a portion of the surface of the wiring board on the first surface side of the base material that overlaps the bellows-shaped portion of the wiring . 16. The wiring board according to claim 11, wherein, when the tension applied to the wiring board and the electrical resistance of the wiring are measured while the wiring board is stretched in the first direction, the electrical resistance indicates a first turning point where an increase in the electrical resistance per unit elongation amount changes when the elongation amount of the wiring board in the first direction is a first elongation amount, and the tension indicates a second turning point where an increase in the tension per unit elongation amount changes when the elongation amount of the wiring board in the first direction is a second elongation amount that is smaller than the first elongation amount. 17. The wiring board according to claim 1 , wherein the first extension amount is 1.1 times or more the second extension amount. The wiring board according to claim 16 or 17, in which the increase in tension per unit of elongation when the elongation of the wiring board in the first direction is smaller than the second elongation is called a first tension increase rate, and the increase in tension per unit of elongation when the elongation of the wiring board in the first direction is larger than the second elongation is called a second tension increase rate, the second tension increase rate being larger than the first tension increase rate. The wiring board according to claim 18, wherein the second tension increase rate is at least twice the first tension increase rate. The wiring board according to any one of claims 16 to 19, wherein the increase in the electrical resistance per unit of elongation amount when the elongation amount of the wiring board in the first direction is smaller than the first elongation amount is referred to as a first electrical resistance increase rate, and the increase in the electrical resistance per unit of elongation amount when the elongation amount of the wiring board in the first direction is larger than the first elongation amount is referred to as a second electrical resistance increase rate, and the second electrical resistance increase rate is larger than the first electrical resistance increase rate. The wiring board according to claim 20, wherein the second electrical resistance increase rate is at least twice the first electrical resistance increase rate. The wiring board according to any one of claims 1 to 21, wherein the substrate includes a thermoplastic elastomer, a silicone rubber, a urethane gel, or a silicon gel. The wiring board according to any one of claims 1 to 22, further comprising a support substrate. The wiring board according to claim 23, wherein the support substrate has a higher elastic modulus than the base material and supports the wiring. The wiring board according to claim 23 or 24, wherein the support substrate is located between the wiring and the first surface of the base material and supports the wiring. The wiring board according to any one of claims 23 to 25, wherein the support substrate includes polyethylene naphthalate, polyimide, polycarbonate, acrylic resin, or polyethylene terephthalate. The wiring board according to any one of claims 1 to 26, further comprising an electronic component electrically connected to the wiring. A method for manufacturing a wiring board, comprising:
A first elongation step of applying tension to an elastic substrate in a first direction, which is one of in-plane directions of a first surface of the substrate, to elongate the substrate;
a wiring forming step of providing wiring extending in the first direction on a first surface side of the base material in a state stretched by the first stretching step;
an adjustment mechanism forming step of providing an adjustment mechanism having a side edge extending in the first direction with a gap between it and the wiring when viewed along a normal direction of the first surface on a first surface side of the base material in an extended state, the adjustment mechanism including a resin or an elastomer on a surface thereof;
and a contraction step of removing the tension from the substrate,
a ratio of an area of the adjustment mechanism to an area of a portion of the wiring board on which the wiring is not provided is 50% or more;
A method for manufacturing a wiring board, wherein when the tension applied to the wiring board and the electrical resistance of the wiring are measured while the wiring board is stretched in the first direction, the electrical resistance shows a first turning point where an increase in the electrical resistance per unit elongation amount changes when the elongation amount of the wiring board in the first direction is a first elongation amount, and the tension shows a second turning point where an increase in the tension per unit elongation amount changes when the elongation amount of the wiring board in the first direction is a second elongation amount that is smaller than the first elongation amount . 29. The method for manufacturing a wiring board according to claim 28, wherein in the adjustment mechanism forming step, the adjustment mechanism is provided on the first surface side of the base material in a state in which the base material is stretched at an elongation rate smaller than that in the first elongation step after the wiring is provided on the base material.