Circuit component and method for manufacturing the same

Abstract

To provide a circuit component that is stretchable, has high electrical conductivity of a circuit wiring even when stretched, and has high adhesion strength to a base material of the circuit wiring, and a manufacturing method for the circuit component.SOLUTION: A circuit component 100 includes a stretchable base material 10, and a circuit wiring 20 formed on the surface of the stretchable base material 10 and including a particle layer 21 composed of particles P containing metal. A plurality of recesses 11 are formed in a region where the circuit wiring 20 is formed on the surface of the stretchable base material 10, and the recesses 11 are filled with particles P.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a circuit component and a method for manufacturing the circuit component. [Background technology]

[0002] In recent years, flexible wiring boards (circuit components) having flexibility and stretchability have been proposed, and are expected to be applied to wearable devices, healthcare-related devices, and the like (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-160965 Summary of the Invention [Problem to be solved by the invention]

[0004] Circuit components used in wearable devices and the like are required to be stretchable to conform to the contours and curves of the body, and the circuit wiring formed thereon must have sufficient conductivity even when stretched. Furthermore, the circuit wiring must also have high adhesion strength to the substrate so that it is less likely to break even after repeated stretching.

[0005] The present invention solves these problems by providing a circuit component that is stretchable, has circuit wiring that has high conductivity even when stretched, and has circuit wiring that has high adhesive strength to a substrate. [Means for solving the problem]

[0006] According to a first aspect of the present invention, there is provided a circuit component comprising: a stretchable substrate; and circuit wiring formed on the surface of the stretchable substrate, the circuit wiring including a particle layer composed of particles containing metal, wherein a plurality of recesses are formed in the area on the surface of the stretchable substrate where the circuit wiring is formed, and the recesses are filled with the particles.

[0007] The stretchable substrate may be silicone rubber. The metal contained in the particles may be at least one of nickel and copper.

[0008] The average depth of the plurality of recesses may be 0.1 μm to 40 μm. The recesses may be blind holes extending from the surface of the stretchable substrate toward the inside, and the extending direction of the plurality of recesses may be random. The interior of the recesses formed on the surface of the stretchable substrate may be wider than the opening of the recesses. When the stretchable substrate is stretched along the surface on which the circuit wiring is formed, the shape of the plurality of recesses formed on the stretchable substrate and the shape of the particle layer may be deformed compared to the unstretched state. When the stretchable substrate is stretched along the surface on which the circuit wiring is formed, the thickness of the particle layer may be thinner compared to the unstretched state.

[0009] The circuit wiring may satisfy the condition expressed by the following formula: (Ra-Rb) / Rb×100≦100 In formula (I), Ra is the electrical resistance value (Ω) of the circuit wiring when the stretchable substrate is stretched along the surface so that a straight line having a predetermined length on the surface on which the circuit wiring of the stretchable substrate is formed in an unstretched state is 10% longer; Rb is the electrical resistance value (Ω) of the circuit wiring in the stretchable substrate in an unstretched state.

[0010] According to a second aspect of the present invention, there is provided a method for manufacturing a circuit component according to the first aspect, the method comprising: preparing the stretchable substrate; stretching the stretchable substrate; irradiating the surface of the stretchable substrate with the laser light to form the plurality of recesses; and forming the particle layer by electroless plating on the surface of the stretchable substrate in the stretched state.

[0011] In stretching the stretchable substrate, the stretchable substrate may be stretched along the surface. In stretching the stretchable substrate, the stretchable substrate may be stretched along the surface so that a straight line having a predetermined length on the surface of the stretchable substrate in an unstretched state is lengthened by 1% to 100%. Before forming the plurality of recesses, the stretchable substrate may be stretched, and in forming the plurality of recesses, the surface of the stretched stretchable substrate may be irradiated with laser light. Alternatively, the stretchable substrate may be stretched after forming the plurality of recesses. In forming the plurality of recesses, the laser light may be irradiated while changing the irradiation angle with respect to the surface of the stretchable substrate one or more times. [Effects of the Invention]

[0012] The circuit component of the present invention is stretchable, and the circuit wiring has high conductivity even when stretched, and further, the circuit wiring has high adhesive strength to the substrate. [Brief explanation of the drawings]

[0013] [Figure 1] 1(a) and 1(b) are enlarged cross-sectional views of the vicinity of the circuit wiring in the circuit component of the embodiment, where Fig. 1(a) is a view of the stretchable substrate in an unstretched state, and Fig. 1(b) is a view of the stretchable substrate in a stretched state. [Figure 2] FIG. 2 is a flowchart illustrating a method for manufacturing a circuit component according to an embodiment. [Figure 3] 3(a) to 3(d) are diagrams illustrating a method for manufacturing a circuit component according to an embodiment. [Figure 4] 4(a) and 4(b) are enlarged cross-sectional views of the vicinity of the circuit wiring in the circuit component of the modified example, where Fig. 4(a) is a view of the stretchable substrate in an unstretched state, and Fig. 4(b) is a view of the stretchable substrate in an stretched state. [Figure 5]5(a) and (b) are SEM photographs of a cross section near the circuit wiring of the circuit component produced in Example 1. Fig. 5(a) is a photograph of the stretchable substrate in an unstretched state, and Fig. 5(b) is a photograph of the stretchable substrate in a stretched state. [Figure 6] FIG. 6 is an SEM photograph of the vicinity of the circuit wiring on the surface of the circuit component produced in Example 1, taken before the stretchable substrate was stretched. [Figure 7] FIG. 7 is a top view of a specimen prepared as a sample for an adhesion test in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0014] [Circuit Components 100] A circuit component 100 of this embodiment will be described. As shown in FIG. 1(a), the circuit component 100 includes a stretchable substrate 10 and circuit wiring 20 formed on the surface 10a of the stretchable substrate 10. The circuit wiring 20 includes a particle layer 21 composed of particles P containing metal. The particle layer 21 is an aggregate of the particles P. A plurality of recesses 11 are formed in the region on the surface 10a of the stretchable substrate 10 where the circuit wiring 20 is formed (hereinafter referred to as the "wiring region" as appropriate). The plurality of recesses 11 are filled with particles P that constitute the particle layer 21.

[0015] The elastic substrate 10 includes an elastic polymer such as rubber. Examples of rubber include silicone rubber, acrylic rubber, isoprene rubber, butyl rubber, styrene butadiene rubber, butadiene rubber, acrylonitrile butadiene rubber (NBR), urethane rubber, chloroprene rubber (CR), ethylene propylene rubber, fluororubber, vulcanized rubber, epichlorohydrin rubber, and chlorinated butyl rubber. Among these, silicone rubber is preferred from the viewpoints of heat resistance and environmental compatibility. Silicone rubber can stably maintain its mechanical properties over a wide temperature range. These rubbers may be used alone or in combination of two or more types.

[0016] Rubber may be the main component of the stretchable substrate 10. That is, the amount of rubber in the stretchable substrate 10 may be, for example, 50 to 100% by weight. If the amount of rubber in the stretchable substrate 10 is within the above range, the stretchable substrate 10 can achieve sufficient stretchability required for, for example, wearable devices.

[0017] The stretchable substrate 10 may be composed of rubber only, or may contain components other than rubber. For example, the stretchable substrate 10 may contain a filler, such as titanium oxide powder or alumina powder, that has the function of improving the adhesion strength of the particle layer 21. Furthermore, the stretchable substrate 10 may further contain general-purpose additives as needed, as long as the effects of the circuit component 100 of this embodiment are not impaired.

[0018] The stretchable substrate 10 is preferably highly flexible so as to obtain sufficient extensibility. The degree of extensibility of the stretchable substrate 10 is not particularly limited, but for example, in the tensile direction, the extensibility is preferably 50% or more (1.5 times or more extensibility in the tensile direction), and more preferably 100% or more (2 times or more extensibility). An extensibility of 50% or 100% in the tensile direction means that the stretchable substrate 10 will not break even if it is stretched in the tensile direction so that a straight line having a predetermined length becomes 50% or 100%, respectively.

[0019] The shape and size of the stretchable substrate 10 are not particularly limited and can be designed appropriately according to the intended use of the circuit component 100. For example, the stretchable substrate 10 may be a plate-like body. The circuit wiring 20 may be formed on one or both of two opposing main surfaces of the plate-like body. When the circuit component 100 is intended for use in a wearable device or the like, the thickness of the plate-like body (the distance between the two opposing main surfaces) may be, for example, less than 3 mm, or 0.1 to 2 mm, so that it can easily conform to the unevenness and curves of the body.

[0020] A plurality of recesses 11 are formed in the wiring region on the surface 10a of the stretchable substrate 10. The recesses 11 are blind holes that extend from the surface 10a of the stretchable substrate 10 toward the inside. The recesses 11 may be formed only in the wiring region. The recesses 11 may be arranged regularly in the wiring region, for example, at equal intervals (equal pitch), or may be arranged irregularly (randomly).

[0021] The average depth of the recesses 11 is preferably 0.1 to 40 μm, 0.5 to 30 μm, or 10 to 15 μm. If the average depth of the recesses 11 is within this range, the adhesion strength of the particle layer 21 formed thereon can be further increased. The average depth of the recesses 11 is determined as the average value of the maximum valley depth Rv of the recesses 11 measured with a laser microscope (for example, Color 3D Laser Microscope VK-9710, manufactured by Keyence Corporation).

[0022] The plurality of recesses 11 formed in the stretchable substrate 10 are filled with metal-containing particles P that form the particle layer 21. The particles P fill the recesses 11 and then continue to spread over the surface 10a of the stretchable substrate 10 to form the particle layer 21. This provides the particle layer 21 with high adhesion strength to the stretchable substrate 10. The particles P are also conductive. In the particle layer 21, adjacent particles P bond and / or come into contact with each other to form conductive paths. This provides the particle layer 21 with conductivity and functions as circuit wiring 20.

[0023] FIG. 1(a) shows the stretchable substrate 10 in a state where no external force is applied, i.e., the stretchable substrate 10 is not stretched. In this state, some particles P are not connected to adjacent particles P but are simply in contact. FIG. 1(b) shows the state where an external force is applied to the stretchable substrate 10, causing the stretchable substrate 10 to be stretched in the elastic region along the surface 10a on which the circuit wiring 20 is formed. The stretchable substrate 10 can be stretched, for example, along the surface 10a. The stretchable substrate 10 may be stretched in multiple directions (e.g., two directions) along the surface 10a, or may be stretched isotropically. When the stretchable substrate 10 is stretched, the recesses 11 formed on the surface 10a expand in the stretching direction (direction parallel to the surface 10a) and their shape is deformed. Following this deformation (expansion) of the recesses 11, the particles P that were simply in contact with each other separate, and the shape of the particle layer 21 is deformed. For example, the thickness of the particle layer 21 becomes thinner compared to when it is not stretched. That is, the thickness 21d2 of the particle layer 21 on the stretched stretchable substrate 10 shown in Fig. 1(b) becomes thinner compared to the thickness 21d1 of the particle layer 21 on the unstretched stretchable substrate 10 shown in Fig. 1(a). When the external force applied to the stretchable substrate 10 is released, the stretchable substrate 10 shrinks to its original size, and the shape of the recesses 11 and the particle layer 21 return to the state shown in Fig. 1(a).

[0024] As described above, in this embodiment, the shape of the particle layer 21 changes in accordance with the deformation of the surface 10a (deformation of the recesses 11) that accompanies the expansion and contraction of the stretchable substrate 10. As a result, even when the stretchable substrate 10 is stretched, the particle layer 21 is less likely to peel off or crack. Furthermore, although some particles P become separated from adjacent particles P due to the stretching of the stretchable substrate 10, sufficient conductive paths are maintained throughout the particle layer 21. Therefore, the circuit wiring 20 having the particle layer 21 is less likely to break even when the stretchable substrate 10 is stretched, and has high conductivity.

[0025] The circuit wiring 20 preferably satisfies the condition represented by the following formula (I). (Ra-Rb) / Rb×100≦200 (I) In formula (I), Ra is the electrical resistance value (Ω) of the circuit wiring 20 when the stretchable substrate 10 is stretched along the surface 10a so that a straight line having a predetermined length L on the surface 10a on which the circuit wiring 20 of the unstretched stretchable substrate 10 is formed is lengthened by 10%. In other words, Ra is the electrical resistance value (Ω) of the circuit wiring 20 when the stretchable substrate 10 is stretched until the straight line of length L becomes a straight line of length 1.1L. Rb is the electrical resistance value (Ω) of the circuit wiring 20 of the stretchable substrate 10 in an unstretched state. The electrical resistance values ​​Ra and Rb can be measured, for example, by the method described in the Examples below.

[0026] The left side of formula (I) represents the rate of change (%) in the electrical resistance value (Ω) of the circuit wiring 20 when the stretchable substrate 10 is stretched by 10%. In other words, the condition represented by formula (I) means that when the stretchable substrate 10 is stretched by 10%, the rate of change (rate of increase) in the electrical resistance value (Ω) of the circuit wiring 20 is 200% or less. When the stretchable substrate 10 is stretched, the thickness of the circuit wiring 20 (particle layer 21) becomes thinner, and the conductivity tends to decrease (electrical resistance value increases). However, in a circuit component 100 that satisfies the condition represented by formula (I), the change in the electrical resistance value of the circuit wiring 20 is small even when the stretchable substrate 10 is stretched.

[0027] It is more preferable that the rate of change (rate of increase) in the electrical resistance value (Ω) of the circuit wiring 20 is 100% or less when the stretchable substrate 10 is stretched by 10%. That is, it is more preferable that the circuit wiring 20 satisfy the condition represented by the following formula (II). (Ra-Rb) / Rb×100≦100 (II) In formula (II), Ra and Rb represent the electrical resistance (Ω) of the circuit wiring 20, similar to formula (I) above.

[0028] It is preferable that the electrical resistance value Ra (Ω) of the circuit wiring 20 when the stretchable substrate 10 is stretched by 10% and the electrical resistance value Rb (Ω) of the circuit wiring 20 when the stretchable substrate 10 is not stretched are both low. Both the electrical resistance values ​​Ra and Rb are preferably 1 MΩ or less, and more preferably 200 Ω or less.

[0029] The material constituting the particles P is not particularly limited as long as it contains a metal and is conductive. The particles P may contain, for example, nickel (Ni), copper (Cu), or both nickel and copper. The particles P may be metal particles, metal compound particles, or a mixture of metal particles and metal compound particles. As will be described in detail later, the particles P can be formed by electroless plating. From the viewpoints of the adhesion strength of the particle layer 21, the precipitation properties of the particles P, and the stability of the electroless plating solution, the particles P are preferably, for example, nickel phosphorus particles, copper nickel particles, copper nickel phosphorus particles, or a mixture thereof.

[0030] The thickness 21d1 of the particle layer 21 when the stretchable substrate 10 is not stretched may be, for example, 0.1 to 20 μm, or 0.2 to 15 μm. If the thickness 21d1 is within the above range, sufficient conductivity can be ensured.

[0031] The circuit wiring 20 may be composed of only the particle layer 21, or may include components other than the particle layer 21 as long as the effects of the circuit component 100 of this embodiment are not impaired. For example, the circuit wiring 20 may include another plating film, such as a Cu or Au film, formed on the particle layer 21 (particles P). The plating film formed on the particles P does not prevent the shape of the particle layer 21 from deforming as the stretchable substrate 10 stretches. On the other hand, a binder resin intended to bind the particles P is not necessary, and the circuit wiring 20 does not need to include a binder resin.

[0032] The circuit component 100 of the present embodiment described above has high conductivity and is resistant to breakage even when the stretchable substrate 10 is stretched because the circuit wiring 20 includes the particle layer 21. Furthermore, the particles P fill the recesses 11 and then continue to spread over the surface 10a of the stretchable substrate 10 to form the particle layer 21. This allows the particle layer 21 to have high adhesive strength to the stretchable substrate 10.

[0033] [Method of manufacturing the circuit component 100] There are no particular limitations on the method for manufacturing the circuit component 100, but it can be manufactured, for example, by the method described below.

[0034] (1) Preparation of the stretchable substrate 10 First, a stretchable substrate 10 is prepared (step S1 in FIG. 2, FIG. 3(a)). The stretchable substrate 10 may be a commercially available product, or may be prepared by molding a material (resin material) such as rubber into any desired shape. There are no particular limitations on the molding method, and general-purpose injection molding, extrusion molding, compression molding, etc. can be used.

[0035] (2) Stretching the stretchable substrate 10 Next, the stretchable substrate 10 is stretched (step S2 in FIG. 2). For example, the stretchable substrate 10 may be fixed to a predetermined jig while in a stretched state. This allows the stretchable substrate 10 to be maintained in a stretched state. The stretchable substrate 10 is preferably stretched along the surface 10a on which the circuit wiring 20 is to be formed. The stretchable substrate 10 may also be stretched in multiple directions (for example, two directions) along the surface 10a, or may be stretched isotropically. The stretchable substrate 10 is preferably stretched so that a straight line having a predetermined length on the surface 10a of the stretchable substrate 10 becomes 1% to 100% or 5% to 50% longer than in an unstretched state.

[0036] (3) Formation of the recess 11 and electroless plating While the stretchable substrate 10 is in a stretched state, the surface 10a is irradiated with laser light to form a plurality of recesses 11 (step S3 in FIG. 2, FIG. 3(b)). Then, while the stretchable substrate 10 is in a stretched state, electroless plating is performed to form a particle layer 21 (circuit wiring 20) in the wiring region of the surface 10a (step S4 in FIG. 2, FIG. 3(c)). In this embodiment, electroless plating does not deposit a metal film (electroless plating film), but instead deposits metal-containing particles P, forming an aggregate of these particles that forms the particle layer 21 (circuit wiring 20). The particles P also deposit inside the recesses 11, filling them and further growing on the surface 10. After the circuit wiring 20 is formed, the stretchable substrate 10 is released from the fixture to which it is fixed, thereby obtaining a circuit component 100 (FIG. 3(d)).

[0037] In this embodiment, the mechanism by which the particle layer 21 is formed by electroless plating, rather than a plating film, is unknown, but is presumed as follows. By performing electroless plating while the stretchable substrate 10 is in a stretched state, first, the electroless plating catalyst (e.g., Pd ions) diffuses into the wiring region where the recesses 11 are formed (surface diffusion). Next, the surface-diffused electroless plating catalyst aggregates, and as this aggregates, fine crystals (particulate plating) are precipitated from the electroless plating solution, forming the particle layer 21. It is presumed that these phenomena are promoted by vibration of the stretched stretchable substrate 10 in the catalyst solution and the electroless plating solution. Note that the above-mentioned mechanism is merely presumed and does not limit the present invention in any way.

[0038] Furthermore, in this embodiment, the particle layer 21 is formed while the stretchable substrate 10 is in a stretched state, and therefore, when the stretchable substrate 10 is subsequently released from stretching, the number of contact points between the particles P increases, thereby increasing the conductivity of the circuit wiring 20 when the stretchable substrate 10 is not stretched.

[0039] The method for selectively forming the circuit wiring 20 in the wiring region of the surface 10a is not particularly limited, and a general-purpose method can be used. For example, after forming the recesses 11, a particle layer 21 is formed over the entire surface 10a by electroless plating, patterned with photoresist, and then removed from the region other than the circuit wiring by etching. Alternatively, the wiring region is roughened by irradiating it with laser light to facilitate the attachment of an electroless plating catalyst. This increases the electroless plating reactivity of the wiring region, and the particle layer 21 is formed only in the wiring region (only the portion irradiated with laser light).

[0040] In this embodiment, the recesses 11 and the circuit wiring 20 are formed by the following method, for example, disclosed in International Publication No. 2018 / 131492. First, (1) a catalytic activity-blocking layer is formed on the stretched surface 10a. Next, (2) a laser beam is irradiated onto the wiring region of the surface 10a on which the catalytic activity-blocking layer has been formed, thereby removing the catalytic activity-blocking layer in the wiring region. At this time, the catalytic activity-blocking layer is removed, and recesses 11 are formed in the wiring region using the laser beam. Next, (3) an electroless catalyst is applied to the wiring region irradiated with the laser beam, and then an electroless plating solution is brought into contact with the wiring region. The catalytic activity-blocking layer inhibits (hinders) the catalytic activity of the electroless plating catalyst applied thereon. Therefore, the generation of the particle layer 21 is suppressed on the catalytic activity-blocking layer. On the other hand, the particle layer 21 is generated in the wiring region because the catalytic activity-blocking layer has been removed. As a result, the circuit wiring 20 is selectively formed in the wiring region. In the method of this embodiment, the use of a catalytic activity hindering layer can strongly suppress plating reactions in areas other than the wiring region, thereby increasing the selectivity of the formation of the particle layer 21. Furthermore, the catalytic activity hindering layer is removed from the wiring region by laser light irradiation, and the surface is roughened. The roughened surface enhances plating reactivity, making it easier to form the particle layer 21 selectively. At the same time, the adhesion strength of the particle layer 21 formed there is also increased.

[0041] The catalytic activity-impeding layer contains a catalytic activity inhibitor (catalyst deactivator) that inhibits (hinders) the catalytic activity of the electroless plating catalyst. The catalytic activity inhibitor (catalyst deactivator) is not particularly limited, but preferred examples include dendritic polymers such as dendrimers and hyperbranched polymers disclosed in International Publication No. 2018 / 131492. These have excellent catalyst deactivation capabilities, and because they are polymers, the catalytic activity-impeding layer can be formed without using a binder resin.

[0042] The electroless plating catalyst is not particularly limited and can be selected from a variety of commonly used catalysts. For example, a plating catalyst solution containing a metal salt such as palladium chloride may be used. The electroless plating solution is also not particularly limited and can be a variety of commonly used catalysts. However, for example, a nickel-phosphorus electroless plating solution or a copper-nickel electroless plating solution using calcium hypophosphite as a reducing agent is preferred. These electroless plating solutions have high deposition properties of particles P and high stability of the electroless plating solution. Furthermore, nickel-phosphorus particles are deposited as particles P from a nickel-phosphorus electroless plating solution, and copper-nickel particles and copper-nickel-phosphorus particles are deposited from a copper-nickel electroless plating solution. The particle layer 21 composed of these particles P has high adhesion strength. Furthermore, if necessary, another plating film, such as an Au film, may be formed on the particle layer 21 by electroless plating or electrolytic plating. For example, the circuit wiring 20 may be composed of multiple layers. The plating film may include an electroless plating film (particle layer 21, base plating film) formed on the substrate and multiple electrolytic plating films formed on the electroless plating film.

[0043] In the manufacturing method of the circuit component 100 described above, the stretchable substrate 10 is stretched before the recesses 11 are formed, and the surface 10a of the stretchable substrate 10 in the stretched state is irradiated with laser light to form the recesses 11. That is, steps S2 and S3 in the flowchart shown in FIG. 2 are performed in this order. The recesses 11 formed in the stretchable substrate 10 shrink after the stretching is released, thereby further increasing the adhesion strength of the circuit wiring 20 (particle layer 20) formed thereon. However, the manufacturing method of the circuit component 100 is not limited thereto. The recesses 11 may be formed in a state where the stretchable substrate 10 is not stretched, and the stretchable substrate may be stretched after the recesses 11 are formed. That is, the order of steps S2 and S3 in the flowchart shown in FIG. 2 may be reversed, and steps S3 and S2 may be performed in this order. Even in the latter method (steps S3 and S2 performed in this order), the presence of the recesses 11 ensures sufficient adhesion strength of the circuit wiring 20 (particle layer 20) formed thereon.

[0044] [Variations] 1(a), the recess 11 of the circuit component 100 shown in FIG. 1 described above has an interior that is narrower than the opening 11a in the surface 10a of the stretchable substrate 10. That is, the cross-sectional area of ​​the cross section 11b of the recess 11 parallel to the surface 10a is smaller than the area of ​​the opening 11a. In the recess 11, there is no cross section 11b parallel to the surface 10a that has a larger cross-sectional area than the opening 11a. However, the present embodiment is not limited to this.

[0045] For example, like the recess 111 of the circuit component 200 shown in FIG. 4(a), the interior of the recess 111 may be larger than the opening 111a in the surface 10a of the stretchable substrate 10. That is, the cross-sectional area of ​​the cross section 111b of the recess 111 parallel to the surface 10a may be larger than the area of ​​the opening 111a. The recess 111 has a cross section 111b parallel to the surface 10a that has a larger cross-sectional area than the area of ​​the opening 111a. If the interior of the recess 111 is larger than the opening 111a, the adhesion strength of the particle layer 21 formed thereon can be further increased.

[0046] The circuit component 200 has the same configuration as the circuit component 100 except for the shape of the recess 111, and can be manufactured by the same method as the circuit component 100 described above. However, the recess 111 can be more easily formed by irradiating the surface 10a of the stretchable substrate 10 with laser light. As shown in FIG. 4(b), when the stretchable substrate 10 is stretched along the surface 10a, the recess 111 becomes a cylindrical non-through hole with a straight inner wall surface. As can be seen from this, cylindrical non-through holes, which are easy to form, are formed in the stretchable substrate 10 in a stretched state, and then the stretching of the stretchable substrate 10 is released, thereby easily forming the recess 111 whose interior is wider than the opening 111a.

[0047] 1(a), the recesses 11 of the circuit component 100 shown in FIG. 1 are blind holes extending inward from the surface 10a of the stretchable substrate 10, and the extending direction is substantially perpendicular to the surface 10a. The extending direction of all of the recesses 11 is substantially constant (substantially the same direction). Therefore, the recesses 11 can be formed by irradiating the surface 10a with laser light from a direction substantially perpendicular to the surface 10a. When forming the recesses 11, it is not necessary to change the irradiation angle of the laser light with respect to the surface 10a. Since the recesses 11 can be formed without changing the irradiation angle of the laser light, the manufacturing time can be reduced. However, this embodiment is not limited to this.

[0048] For example, the extending direction of the multiple recesses 11 may not be constant but may be different, may be multiple directions (for example, two directions), or may be random. If the extending directions of the multiple recesses 11 are multiple directions or random, the adhesion strength of the particle layer 21 formed thereon can be further increased. Such multiple recesses 11 are formed, for example, by irradiating the surface 10a with laser light from multiple directions or random directions. For example, in forming the multiple recesses 11, the laser light is irradiated while changing the irradiation angle of the laser light with respect to the surface 10a one or more times. This makes it possible to form multiple recesses 11 extending along the irradiation angles (irradiation directions) of the respective laser light.

[0049] The above-described embodiment and multiple modified examples may be combined with each other as long as they do not exclude each other. [Example]

[0050] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples and comparative examples.

[0051] [Example 1] In this example, a circuit component 100 shown in FIG. 1 was fabricated.

[0052] (1) Forming of the stretchable substrate 10 Silicone resin (silicone rubber) (product name: KJR632, manufactured by Shin-Etsu Chemical Co., Ltd.) was molded into a flat plate by compression molding to obtain the stretchable substrate 10 (mold temperature: 170° C.).

[0053] (2) Stretching the stretchable substrate 10 Four through-holes were formed at each of the four corners of the stretchable substrate 10 (flat plate). More specifically, through-holes were formed at each vertex of a 20 mm × 20 mm square on the surface 10a of the stretchable substrate 10. Next, a jig was prepared for stretching, with a protrusion at each vertex of a 30 mm × 30 mm square on a plane. The stretchable substrate 10 was stretched along the surface 10a, and the protrusions of the jig were engaged with each through-hole of the stretchable substrate 10. In this way, the stretchable substrate 10 was fixed to the jig in a state where the straight line of 20 mm in length was 30 mm, i.e., in a 50% stretched state.

[0054] (3) Formation of the recess 11 and the circuit wiring 20 In this example, the recesses 11 and the circuit wiring 20 (particle layer 21) were formed by the method described below.

[0055] (a) Formation of catalytically active interference layer A catalytic activity-blocking layer containing a hyperbranched polymer represented by the following formula (1), which is a catalyst deactivator, was formed on the surface 10a of the stretchable substrate 10 in a stretched state. The hyperbranched polymer represented by formula (1) was synthesized by the method disclosed in WO 2018 / 131492. In formula (1), R 0 is a vinyl group or an ethyl group.

[0056] [ka]

[0057] The molecular weight of the synthesized hyperbranched polymer was measured by GPC (gel permeation chromatography). The molecular weight was number average molecular weight (Mn) = 9,946, and weight average molecular weight (Mw) = 24,792, and the number average molecular weight (Mn) and weight average molecular weight (Mw) unique to the hyperbranched structure were significantly different values.

[0058] The synthesized polymer represented by formula (1) was dissolved in propylene glycol monomethyl ether (SP value: 10.4) to prepare a polymer solution with a polymer concentration of 0.5 wt %. The stretchable substrate 10 was immersed in the polymer solution at room temperature for 5 seconds, and then dried in a 100°C dryer for 10 minutes. This formed a catalytic activity interference layer on the surface of the stretchable substrate 10. The thickness of the catalytic activity interference layer was 100 nm.

[0059] (b) Laser writing, forming recesses 11 The area (wiring area, wiring pattern) on the surface 10a of the stretchable substrate 10 where the circuit wiring 20 was to be formed was irradiated with laser light (laser drawing). Specifically, a UV laser (Keyence Corporation, 3-Axis UV Laser Marker MD-U1000C) was used to draw the wiring area in the form of diagonal lines at a 20 μm pitch under laser drawing conditions of 80% power, 1000 mm / s speed, and 40 kHz frequency. The area irradiated with the laser light had the catalytic activity-blocking layer 80 removed and was roughened.

[0060] The catalytic activity-blocking layer was removed, and multiple recesses 11 were formed in the wiring region using laser light. The laser light was irradiated from a direction approximately perpendicular to the surface 10a, and all recesses 11 were formed without changing the irradiation angle. As a result, all of the recesses 11 formed extended inward from the surface 10a in the same direction, approximately perpendicular to the surface 10a. The average depth of the recesses 11 was measured using a color 3D laser microscope VK-9710 manufactured by Keyence Corporation. The average depth of the recesses 11 (average value of maximum valley depth Rv) was 10 μm.

[0061] (c) Formation of particle layer 21 The stretchable substrate 10 was immersed for 5 minutes in a commercially available aqueous solution of palladium chloride (PdCl2) (Activator, manufactured by Okuno Chemical Industries) adjusted to 30° C. Thereafter, the stretchable substrate 10 was taken out of the aqueous solution of palladium chloride and washed with water.

[0062] The stretchable substrate 10 was immersed for 10 minutes in an electroless nickel-phosphorus plating solution (Top Nicoron LPH-L, pH 6.5, manufactured by Okuno Pharmaceutical Industries) adjusted to 60° C. A particle layer 21 (aggregate of electroless nickel-phosphorus particles) grew to a thickness of approximately 1 μm in the laser-drawn portion (wiring area) on the stretchable substrate 10.

[0063] Next, electrolytic copper plating was carried out to laminate a 5 μm thick copper plating film on the particle layer 21 (particles P), thereby forming the circuit wiring 20. In this way, the circuit component 100 of this example was obtained.

[0064] [Example 2] A circuit component 100 was produced in the same manner as in Example 1, except that in the stretching step of the stretchable substrate 10, the stretchable substrate 10 was stretched by 20%.

[0065] [Example 3] (1) Forming of the stretchable substrate 10 A flat-plate-shaped stretchable substrate 10 was formed in the same manner as in Example 1, except that chloroprene rubber (CR) was used instead of silicone rubber.

[0066] (2) Stretching the stretchable substrate 10 The stretchable substrate 10 was stretched and fixed to a jig in the same manner as in Example 1, except that the stretchable substrate 10 was stretched by 20%.

[0067] (3) Formation of the recess 11 and the circuit wiring 20 In forming the recesses 11, the irradiation direction of the laser beam was changed once. Specifically, a plurality of recesses 11 was formed by irradiating the surface 10a with the laser beam from a direction substantially perpendicular to the surface 10a, and then a plurality of recesses 11 was formed by irradiating the surface 10a with the laser beam from a direction tilted at 45° with respect to the surface 10a. As a result, the formed recesses 11 extended inward from the surface 10a in two directions: a direction substantially perpendicular to the surface 10a and a direction tilted at 45° with respect to the surface 10a. In this example, the laser beam irradiation conditions were adjusted so that the average depth of the recesses 11 was 12 μm.

[0068] Except for the method of forming the recesses 11 described above, the circuit wiring 20 was formed in the same manner as in Example 1. In this way, the circuit component 100 of this example was obtained.

[0069] [Example 4] (1) Forming of the stretchable substrate 10 A flat, stretchable substrate 10 was formed in the same manner as in Example 1, except that acrylonitrile-butadiene rubber (NBR) was used instead of silicone rubber.

[0070] (2) Stretching the stretchable substrate 10 The stretchable substrate 10 was stretched and fixed to a jig in the same manner as in Example 1, except that the stretchable substrate 10 was stretched by 10%.

[0071] (3) Formation of the recess 11 and the circuit wiring 20 Circuit wiring 20 was formed in the same manner as in Example 1, except that in forming recesses 11, the laser light irradiation conditions were adjusted so that the average depth of recesses 11 was 15 μm. In this way, circuit component 100 of this example was obtained.

[0072] [Comparative Example] In this comparative example, the catalytic activity-hindering layer was removed by laser light irradiation, but no recesses 11 were formed. Except for this, the circuit component of this comparative example was produced in the same manner as in Example 1.

[0073] [Evaluation of circuit components] The circuit components fabricated in Examples 1 to 4 and Comparative Example were evaluated as follows.

[0074] (1) SEM observation of circuit components The surface and cross section near the circuit wiring of the circuit component 100 produced in Example 1 were subjected to SEM observation. Fig. 5(a) is a cross-sectional SEM photograph of the stretchable substrate 10 in an unstretched state, and Fig. 5(b) is a cross-sectional SEM photograph of the stretchable substrate 10 in a stretched state. Fig. 6 is an SEM photograph of the surface near the circuit wiring of the stretchable substrate 10 in an unstretched state.

[0075] As shown in Figures 5(a), (b) and 6, the circuit wiring 20 is not a film-like metal (plated film) but includes a particle layer 21 composed of particles P, and the recesses 11 are filled with the particles P. It was also confirmed that the thickness of the particle layer 21 on the stretched stretchable substrate 10 shown in Figure 5(b) was thinner than that of the particle layer 21 on the unstretched stretchable substrate 10 shown in Figure 5(a). In other words, the shape of the particle layer 21 changed in accordance with the deformation of the surface (deformation of the recesses 11) accompanying the stretching of the stretchable substrate 10.

[0076] (2) Adhesion test (a) Peel test As samples for adhesion tests for Examples 1 to 4 and the Comparative Example, samples S were prepared, each having a cross-shaped circuit wiring 20 formed on an elastic substrate 10, as shown in FIG. 7. For each sample S, a peel test was conducted in which tape (Teraoka Seisakusho, polyester film adhesive tape 631S#25) was peeled from the elastic substrate 10 at a peel angle of 90 degrees with a strength of 5 N / cm, and the sample was evaluated according to the following evaluation criteria. The peel test was conducted in each of two orthogonal directions on the circuit wiring 20 (a total of two times). The evaluation results are shown in Table 1.

[0077] <Evaluation criteria for peel test> ◯: No peeling of the plating film occurred in the peeling test. ×: Peeling of the plating film occurred during the peeling test.

[0078] (b) Electrical resistance value after adhesion test After the above-described adhesion test was carried out on Sample S of Examples 1 to 4 and Comparative Example, the electrical resistance was measured and evaluated according to the following evaluation criteria. A digital multimeter (FLUKE-177, manufactured by TFF Fluke Corporation) was used for the measurement. The evaluation results are shown in Table 1.

[0079] <Evaluation criteria for electrical resistance after adhesion test> Good: The electrical resistance after the adhesion test is 1 MΩ or less. ×: The electrical resistance value after the adhesion test exceeds 1 MΩ.

[0080] (3) Electrical resistance of circuit wiring For the circuit components 100 fabricated in Examples 1 and 2 and the Comparative Example, the electrical resistance values ​​Rb in an unstretched state (normal) and the electrical resistance values ​​Ra in a stretched state were measured. The electrical resistance value Ra was measured in a state in which the stretchable substrate 10 was stretched along the surface 10a using the same stretching method as used to stretch the stretchable substrate 10 during fabrication of the circuit component 100 described above, so that a straight line having a predetermined length L in the wiring region of the surface 10a was extended by 10%. The electrical resistance was measured using the same method as used to measure the electrical resistance after the adhesion test described above. The measured electrical resistance values ​​Ra and Rb were each evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1. Note that, in the following evaluation criteria, if the evaluation result is A or B, it can be determined that the resistance of the circuit wiring 20 is sufficiently low and exhibits high conductivity.

[0081] <Evaluation criteria for electrical resistance of circuit wiring> A: The electrical resistance values ​​Ra and Rb are 200 Ω or less. B: The electrical resistance values ​​Ra and Rb are greater than 200Ω and less than or equal to 1MΩ. C: Electrical resistance values ​​Ra and Rb are greater than 1 MΩ.

[0082] (4) Rate of change in electrical resistance of circuit wiring For the circuit components 100 of Examples 1 and 2 and the comparative example whose electrical resistance values ​​Ra and Rb were measured, the rate of change Rc (%) of the electrical resistance value (Ω) of the circuit wiring 20 when the stretchable substrate 10 was stretched by 10% was calculated using the following formula (III). The rate of change Rc (%) is the left side of the above formulas (I) and (II). Rc = (Ra - Rb) / Rb × 100 (III) In formula (III), Ra and Rb represent the electrical resistance (Ω) of the circuit wiring 20, as in formula (I) above. Rc is the rate of change (%) of the electrical resistance (Ω) of the circuit wiring 20 when the stretchable substrate 10 is stretched by 10%.

[0083] The obtained change rates Rc were evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1.

[0084] <Evaluation criteria for the rate of change in electrical resistance of circuit wiring> A: The rate of change Rc is 100% or less, that is, the condition of formula (II) is satisfied. B: The rate of change Rc is more than 100% and not more than 200%, that is, the condition of formula (II) is not satisfied, but the condition of formula (I) is satisfied. C: The rate of change Rc exceeds 200%, that is, the conditions of formula (I) and formula (II) are not satisfied.

[0085] [Table 1]

[0086] As shown in Table 1, the circuit components produced in Examples 1 to 4 showed no peeling in the peel test, and the electrical resistance values ​​after the peel test were lower than those of the comparative example. These results confirmed that the circuit wiring 20 in the circuit components produced in Examples 1 to 4 had high adhesion. Furthermore, the circuit components produced in Examples 1 and 2 had sufficiently low electrical resistance values ​​Rb in the unstretched state and Ra in the stretched state. Furthermore, the circuit components produced in Examples 1 and 2 also had low rates of change Rc in the electrical resistance value of the circuit wiring, satisfying the conditions expressed by formula (I) or formula (II). These results confirmed that the circuit components 100 produced in Examples 1 and 2 were resistant to breakage even when the stretchable substrate 10 was stretched, and had high conductivity.

[0087] On the other hand, the circuit component of the comparative example, in which the recess 11 was not formed in the wiring region of the stretchable substrate 10, experienced peeling in the peel test and had a high electrical resistance value after the peel test. That is, the adhesion of the circuit wiring 20 of the comparative example was low. Furthermore, in the comparative example, the electrical resistance value Ra of the stretchable substrate 10 in the stretched state was high. As a result, the rate of change Rc of the electrical resistance value of the circuit wiring was also high, and the conditions expressed by formulas (I) and (II) were not satisfied. That is, the circuit component produced in the comparative example had low conductivity when the stretchable substrate 10 was stretched. [Industrial Applicability]

[0088] The circuit component of the present invention is stretchable, and the circuit wiring maintains high conductivity even when stretched. Furthermore, the circuit wiring has high adhesion strength to the substrate. Therefore, the circuit component of the present invention is applicable to wearable devices and healthcare-related devices. [Explanation of symbols]

[0089] 10 Stretchable base material 11,111 recess 20 Circuit wiring 21 Particle layer 100,200 circuit components P particles

Claims

1. A circuit component, A stretchable substrate; and circuit wiring including a particle layer formed on the surface of the stretchable substrate and composed of particles including a metal, a plurality of recesses are formed in an area on the surface of the stretchable substrate where the circuit wiring is formed, The recessed portion is filled with the particles.

2. 2. The circuit component according to claim 1, wherein the elastic substrate comprises silicone rubber.

3. 3. The circuit component according to claim 1, wherein the metal contained in the particles is at least one of nickel and copper.

4. 4. The circuit component according to claim 1, wherein the average depth of the plurality of recesses is 0.1 μm to 40 μm.

5. 5. The circuit component according to claim 1, wherein the recesses are blind holes extending from the surface of the stretchable substrate toward the interior thereof, and the extending directions of the recesses are random.

6. 6. The circuit component according to claim 1, wherein the inside of the recess formed on the surface of the stretchable substrate is wider than the opening of the recess.

7. When the stretchable substrate is stretched along the surface on which the circuit wiring is formed, The circuit component according to any one of claims 1 to 6, wherein the shape of the plurality of recesses formed in the stretchable substrate and the shape of the particle layer are deformed compared to a state in which the stretchable substrate is not stretched.

8. When the stretchable substrate is stretched along the surface on which the circuit wiring is formed, The circuit component according to claim 7 , wherein the particle layer has a thickness that is smaller than that in an unstretched state.

9. The circuit component according to any one of claims 1 to 8, wherein the circuit wiring satisfies the condition represented by the following formula: (Ra-Rb) / Rb×100≦100 In the above formula, Ra is the electrical resistance value (Ω) of the circuit wiring when the stretchable substrate is stretched along the surface so that a straight line having a predetermined length on the surface on which the circuit wiring is formed of the stretchable substrate in an unstretched state is 10% longer; Rb is the electrical resistance value (Ω) of the circuit wiring in the stretchable substrate in an unstretched state.

10. The method for manufacturing the circuit component according to any one of claims 1 to 9, providing the stretchable substrate; stretching the stretchable substrate; irradiating a surface of the stretchable substrate with laser light to form the plurality of recesses; and forming the particle layer on the surface of the stretchable substrate in a stretched state by electroless plating.

11. The method for producing a circuit component according to claim 10 , wherein the stretchable substrate is stretched along the surface.

12. 12. The method for manufacturing a circuit component according to claim 10 or 11, wherein the stretchable substrate is stretched along the surface so that a straight line having a predetermined length on the surface of the stretchable substrate in an unstretched state is lengthened by 1% to 100%.

13. Before forming the plurality of recesses, the stretchable substrate is stretched; The method for manufacturing a circuit component according to any one of claims 10 to 12, wherein the laser light is irradiated onto the surface of the stretchable substrate in a stretched state in forming the plurality of recesses.

14. The method for producing a circuit component according to any one of claims 10 to 12, wherein the stretchable substrate is stretched after the formation of the plurality of recesses.

15. The method for manufacturing a circuit component according to any one of claims 10 to 14, wherein, in forming the plurality of recesses, the laser light is irradiated while changing the irradiation angle with respect to the surface of the stretchable substrate one or more times.

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