JP2019075416A - Wiring board and manufacturing method of wiring board - Google Patents

Abstract

To provide a wiring board which hardly causes failure such as damage.SOLUTION: A wiring board 10 comprises: an elastic substrate 20 which includes a first surface and a second surface located on the opposite side to the first surface; a support substrate 40 which is bonded to the substrate from the first surface side of the substrate and has an elastic modulus higher than that of the substrate; wiring 52 which is provided on the support substrate so as to be connected to an electrode of an electronic component 51 mounted on the support substrate, and which has a bellows-shaped part where crest portions and trough portions in the normal direction of the first surface of the substrate repeatedly appear along the in-plane direction of the first surface of the substrate; and a stress adjusting mechanism 30, made up of a first reinforcement member 31 and a second reinforcement member 32, which is provided in a portion of the substrate so as to prevent stress generated on the substrate due to expansion and contraction from being transmitted to the support substrate.SELECTED DRAWING: Figure 1

Description

  An embodiment of the present disclosure relates to a wiring substrate including a substrate and a supporting substrate provided with a wiring joined to the substrate and connected to an electronic component. In addition, an embodiment of the present disclosure relates to a method of manufacturing a wiring board.

  In recent years, research has been conducted on electronic devices having deformability such as stretchability. For example, Patent Document 1 discloses a stretchable wiring board including a substrate and a wiring provided on the substrate. In Patent Document 1, a manufacturing method is employed in which a circuit is provided on a substrate in a stretched state in advance, and the substrate is relaxed after forming the circuit. Patent Document 1 intends to operate the thin film transistor on the substrate well in both the extended state and the relaxed state of the substrate.

JP 2007-281406 A

  The wiring board includes not only a portion having resistance to deformation such as expansion and contraction but also a portion susceptible to breakage due to the deformation. For this reason, when the circuit is provided on the substrate in a stretched state in advance, a defect such as breakage is likely to occur in the wiring substrate.

  An embodiment of the present disclosure aims to provide a wiring substrate and a method of manufacturing the wiring substrate that can effectively solve such a problem.

  According to an embodiment of the present disclosure, there is provided a substrate having stretchability and including a first surface and a second surface opposite to the first surface, and bonded to the substrate from the first surface side of the substrate A supporting substrate having an elastic coefficient higher than that of the substrate, and a wire provided on the supporting substrate so as to be connected to an electrode of an electronic component mounted on the supporting substrate, Wiring having a bellows-shaped portion in which peaks and valleys in the normal direction of one surface repeatedly appear along the in-plane direction of the first surface of the substrate, and stress caused in the substrate due to expansion or contraction And a stress adjusting mechanism provided on a part of the substrate to suppress transfer to the substrate.

  In the wiring substrate according to the embodiment of the present disclosure, the stress adjusting mechanism may be configured to overlap the electronic component mounted on the support substrate when viewed along the normal direction of the first surface. A first reinforcing member located on a surface and having an elastic coefficient higher than that of the substrate, and an electronic component mounted on the support substrate when viewed along the normal direction of the first surface. And a second reinforcing member located on the second surface of the substrate and having a modulus of elasticity higher than that of the substrate. In this case, the thickness of the portion of the substrate overlapping the first reinforcing member and the second reinforcing member when viewed along the normal direction of the first surface is the thickness of the first surface of the substrate. The thickness may be smaller than the thickness of a portion not overlapping the first reinforcing member or the second reinforcing member when viewed along the normal direction. The first reinforcing member or the second reinforcing member may include a metal layer.

  In the wiring substrate according to the embodiment of the present disclosure, the stress adjusting mechanism may be configured to overlap the second part of the substrate so as to overlap the electronic component mounted on the support substrate when viewed along the normal direction of the first surface. You may provide the several slit formed in the surface. In this case, the depth of the slit may be 30% or more of the thickness of the substrate.

  In the wiring board according to the embodiment of the present disclosure, the amplitude of the bellows-shaped portion of the wiring may be 1 μm or more.

  In the wiring substrate according to an embodiment of the present disclosure, the substrate may include silicone rubber.

  In the wiring board according to an embodiment of the present disclosure, the wiring may include a plurality of conductive particles.

  The wiring substrate according to an embodiment of the present disclosure may further include an electronic component having an electrode located on the support substrate and electrically connected to the wiring.

  One embodiment of the present disclosure is a method of manufacturing a wiring substrate, including a first surface and a second surface opposite to the first surface, and applying tensile stress to a substrate having elasticity, A stretching step of stretching the substrate, and a first reinforcing member having a modulus of elasticity higher than that of the substrate provided on the first surface of the substrate, the second reinforcing member having a modulus of elasticity higher than the modulus of elasticity of the substrate A step of providing a reinforcing member on the second surface of the substrate, and a support substrate having an elastic coefficient higher than that of the substrate, wherein the wiring is connected to an electrode of an electronic component mounted on the support substrate Bonding the support substrate provided with the second substrate to the substrate in a stretched state from the first surface side, and a contraction step of removing the tensile stress from the substrate, and the bonding step includes the steps of: Before when viewed along the surface normal direction The electronic component mounted on the support substrate is implemented to overlap the first reinforcing member and the second reinforcing member, and after the tensile stress is removed from the substrate, the normal direction of the first surface of the wiring is removed. The ridges and valleys in the direction normal to the first surface of the portion not overlapping with the first reinforcing member and the second reinforcing member when viewed along the in-plane direction of the first surface It is a manufacturing method of a wiring board which has a bellows shape part which appears repeatedly.

  One embodiment of the present disclosure is a method of manufacturing a wiring substrate, including a first surface and a second surface opposite to the first surface, and applying tensile stress to a substrate having elasticity, And a supporting substrate having a stretching step of stretching the substrate, and a supporting substrate having an elastic coefficient higher than that of the substrate, wherein the supporting substrate is provided with a wire connected to an electrode of an electronic component mounted on the supporting substrate. And a bonding step of bonding the substrate in a stretched state from the first surface side, and a shrinking step of removing the tensile stress from the substrate, which is performed between the bonding step and the shrinking step. And a slit forming step of forming a plurality of slits in the second surface of a portion overlapping with the electronic component mounted on the support substrate when viewed along the normal direction of the first surface among them. The tensile stress is removed from After that, when viewed in the normal direction of the first surface in the wiring, the ridges and valleys in the normal direction of the first surface are portions that do not overlap with the slits when viewed in the normal direction of the first surface. It is a manufacturing method of a wiring board which has a bellows shape part which repeatedly appears along an in-plane direction.

  In the method of manufacturing a wiring substrate according to an embodiment of the present disclosure, the depth of the slit may be 30% or more of the thickness of the substrate.

  According to the embodiment of the present disclosure, it is possible to suppress the occurrence of a defect in the wiring substrate due to the expansion and contraction of the substrate.

It is a sectional view showing the wiring board concerning one embodiment. FIG. 1 is a plan view showing a wiring board according to an embodiment. It is sectional drawing which expands and shows an example of wiring of the wiring board shown in FIG. 1, and its periphery. It is sectional drawing which expands and shows the wiring of the wiring board shown in FIG. 1, and the other example of the component of the periphery of it. It is a figure for demonstrating the manufacturing method of the wiring board shown in FIG. It is sectional drawing which shows the wiring board which concerns on a 1st modification. It is a bottom view showing the wiring board concerning the 1st modification. It is sectional drawing which expands and shows an example of wiring of the wiring board shown in FIG. 6, and its periphery. FIG. 7 is a diagram for illustrating a method of manufacturing the wiring board shown in FIG. 6.

  Hereinafter, the configuration of a wiring board according to an embodiment of the present disclosure and a method of manufacturing the same will be described in detail with reference to the drawings. Note that the embodiments described below are examples of embodiments of the present disclosure, and the present disclosure is not construed as being limited to these embodiments. Moreover, in the present specification, terms such as “substrate”, “substrate”, “sheet” and “film” are not distinguished from one another based on only the difference in designation. For example, "substrate" is a concept including a member that can be called a substrate, a sheet or a film. Furthermore, as used herein, the terms such as "parallel" and "orthogonal", values of length and angle, etc., which specify the shape and geometrical conditions and their degree, are strictly bound. Instead, it shall be interpreted including the range to which the same function can be expected. In the drawings referred to in this embodiment, the same portions or portions having similar functions may be denoted by the same reference numerals or similar reference numerals, and repeated description thereof may be omitted. Further, the dimensional ratio of the drawings may be different from the actual ratio for convenience of explanation, or a part of the configuration may be omitted from the drawings.

  Hereinafter, an embodiment of the present disclosure will be described with reference to FIGS. 1 to 5.

(Wiring board)
First, the wiring board 10 according to the present embodiment will be described. 1 and 2 are a sectional view and a plan view showing the wiring board 10, respectively. The cross-sectional view shown in FIG. 1 is a view in which the wiring substrate 10 of FIG. 2 is cut along the line A-A.

  The wiring substrate 10 illustrated in FIG. 1 includes a substrate 20, a stress adjustment mechanism 30, a support substrate 40, an electronic component 51, and a wire 52. Hereinafter, each component of the wiring board 10 will be described.

〔substrate〕
The substrate 20 is a plate-like member configured to have stretchability. The substrate 20 includes a first surface 21 located on the electronic component 51 and wiring 52 side, and a second surface 22 located on the opposite side of the first surface 21. The thickness of the substrate 20 is, for example, 10 mm or less, more preferably 1 mm or less. By reducing the thickness of the substrate 20, the force required for expansion and contraction of the substrate 20 can be reduced. Further, by reducing the thickness of the substrate 20, the thickness of the entire product using the wiring substrate 10 can be reduced. Thereby, for example, when the product using the wiring substrate 10 is a sensor attached to a part of the body such as a human arm, the wearing feeling can be reduced. The thickness of the substrate 20 may be 10 μm or more.

  As an example of a parameter representing the stretchability of the substrate 20, the elastic modulus of the substrate 20 can be mentioned. The elastic modulus of the substrate 20 is, for example, 10 MPa or less, more preferably 1 MPa or less. By using the substrate 20 having such an elastic coefficient, the whole wiring substrate 10 can be made stretchable. In the following description, the elastic modulus of the substrate 20 is also referred to as a first elastic modulus. The first elastic modulus of the substrate 20 may be 1 kPa or more.

  As a method of calculating the first elastic modulus of the substrate 20, a method of performing a tensile test using a sample of the substrate 20 can be adopted. As a method of preparing a sample of the substrate 20, a method of taking out a part of the substrate 20 as a sample from the wiring substrate 10 or a method of taking out a part of the substrate 20 before forming the wiring substrate 10 as a sample can be considered. Besides, as a method of 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 the existing database of materials is used. It can also be adopted.

As another example of the parameter indicating the stretchability of the substrate 20, the flexural rigidity of the substrate 20 can be mentioned. The flexural rigidity is the product of the moment of inertia of area of the target member and the modulus of elasticity of the material constituting the target member, and the unit is N · m ² or Pa · m ⁴ . The geometrical moment of inertia in section of the substrate 20 is calculated based on the section in the case where the substrate 20 is cut along a plane orthogonal to the expansion and contraction direction of the wiring substrate 10. In the following description, the bending stiffness of the substrate 20 is also referred to as a first bending stiffness.

  As an example of the material which comprises the board | substrate 20, a thermoplastic elastomer, silicone rubber, a urethane gel, a silicone gel etc. can be mentioned. As thermoplastic elastomers, polyurethane elastomers, styrene thermoplastic elastomers, olefin thermoplastic elastomers, polyvinyl chloride thermoplastic elastomers, ester thermoplastic elastomers, amide thermoplastic elastomers, 1,2-BR thermoplastic elastomers, A fluorine-type thermoplastic elastomer etc. can be used. In view of mechanical strength and abrasion resistance, it is preferable to use a urethane-based elastomer. Furthermore, silicone rubber is excellent in heat resistance, chemical resistance, and flame retardancy, and is preferable as a material of the substrate 20.

[Stress adjustment mechanism]
The stress adjustment mechanism 30 is a mechanism provided on a part of the substrate 20 in order to suppress the transfer of the stress generated on the substrate 20 due to expansion and contraction to the support substrate 40. In the present embodiment, as shown in FIG. 1, the stress adjusting mechanism 30 includes a first reinforcing member 31 positioned on the first surface 21 of the substrate 20 and a second reinforcing member positioned on the second surface 22 of the substrate 20. And a reinforcing member 32.

  Each of the first reinforcing member 31 and the second reinforcing member 32 has a modulus of elasticity larger than the first modulus of elasticity of the substrate 20. The elastic coefficient of the first reinforcing member 31 and the second reinforcing member 32 is, for example, 1 GPa or more, and more preferably 10 GPa or more. The modulus of elasticity of the first reinforcing member 31 and the second reinforcing member 32 may be 100 times or more or 1000 times or more of the first modulus of elasticity of the substrate 20. By providing the substrate 20 with the stress adjusting mechanism 30 including the first reinforcing member 31 and the second reinforcing member 32 as described above, the stress generated in the portion overlapping the stress adjusting mechanism 30 in the substrate 20 is on the supporting substrate 40 side. Transmission can be suppressed. Thereby, it is possible to suppress breakage or the like of a portion of the support substrate 40 and the components on the support substrate 40 overlapping the stress adjustment mechanism 30. In the following description, the elastic coefficients of the first reinforcing member 31 and the second reinforcing member 32 are also referred to as a second elastic coefficient.

  As shown in FIGS. 1 and 2, the stress adjusting mechanism 30 including the first reinforcing member 31 and the second reinforcing member 32 is a supporting substrate when viewed along the normal direction of the first surface 21 of the substrate 20. It overlaps with the electronic component 51 located on the top 40. In this case, the first reinforcing member 31 and the second reinforcing member 32 function to suppress the transfer of the stress generated in the substrate 20 due to the expansion and contraction to the electronic component 51 on the support substrate 40. As a result, it is possible to suppress that the electronic component 51 is deformed or damaged.

  The second elastic modulus of the first reinforcing member 31 and the second reinforcing member 32 may be 500 GPa or less. Further, the second elastic modulus of the first reinforcing member 31 and the second reinforcing member 32 may be 500,000 times or less of the first elastic modulus of the substrate 20. The method of calculating the second elastic modulus of the first reinforcing member 31 and the second reinforcing member 32 is the same as that of the substrate 20. Note that “overlap” means that two components overlap when viewed along the normal direction of the first surface 21 of the substrate 20. The elastic coefficient of the first reinforcing member 31 and the elastic coefficient of the second reinforcing member 32 may be the same or different.

  In addition, the first reinforcing member 31 and the second reinforcing member 32 have bending stiffness greater than the first bending stiffness of the substrate 20. The bending rigidity of the first reinforcing member 31 and the second reinforcing member 32 may be 100 times or more or 1000 times or more of the first bending rigidity of the substrate 20. In the following description, the bending stiffness of the first reinforcing member 31 and the second reinforcing member 32 is also referred to as a second bending stiffness.

Examples of the material constituting the first reinforcing member 31 and the second reinforcing member 32 include a metal layer containing a metal material, a general thermoplastic elastomer, an acrylic type , a urethane type , an epoxy type , a polyester type , an epoxy type , Examples thereof include vinyl ether- based , polyene-thiol- based , silicone-based oligomers, polymers and the like. Examples of metal materials include copper, aluminum, stainless steel and the like. The thickness of the first reinforcing member 31 and the second reinforcing member 32 is, for example, 10 μm or more. Among the above-mentioned materials, the metal layer has a large elastic modulus, can be finely processed by etching, and is more preferable.

[Supporting substrate]
The support substrate 40 is a plate-like member configured to have elasticity lower than that of the substrate 20. The support substrate 40 includes a second surface 42 located on the substrate 20 side and a first surface 41 located on the opposite side of the second surface 42. In the example shown in FIG. 1, the support substrate 40 supports the electronic component 51 and the wiring 52 on the first surface 41 side. Further, the support substrate 40 is bonded to the first surface of the substrate 20 on the second surface 42 side. For example, an adhesive layer 60 containing an adhesive may be provided between the substrate 20 and the support substrate 40. As a material which comprises adhesion layer 60, an acrylic adhesive, silicone system adhesive etc. can be used, for example. The thickness of the adhesive layer 60 is, for example, 5 μm or more and 200 μm or less. Although not shown, the second surface 42 of the support substrate 40 may be bonded to the first surface 21 of the substrate 20 by room temperature bonding. In this case, the adhesive layer may not be provided between the substrate 20 and the support substrate 40.

  As described later, when the tensile stress is removed from the substrate 20 bonded to the support substrate 40 and the substrate 20 contracts, a bellows-shaped portion is formed on the support substrate 40. The characteristics and dimensions of the support substrate 40 are set to facilitate formation of such bellows. For example, the support substrate 40 has a modulus of elasticity greater than the first modulus of elasticity of the substrate 20. In the following description, the elastic modulus of the support substrate 40 is also referred to as a third elastic modulus.

  The third elastic modulus of the support substrate 40 is, for example, 100 MPa or more, and more preferably 1 GPa or more. The third elastic modulus of the support substrate 40 may be 100 times or more or 1000 times or more of the first elastic modulus of the substrate 20. The thickness of the support substrate 40 is, for example, 10 μm or less, more preferably 5 μm or less. By increasing the elastic coefficient of the support substrate 40 or reducing the thickness of the support substrate 40, the bellows-shaped portion is easily formed on the support substrate 40 as the substrate 20 shrinks. As a material which comprises the support substrate 40, polyethylene naphthalate, a polyimide, a polycarbonate, an acrylic resin, a polyethylene terephthalate etc. can be used, for example.

  The third elastic modulus of the support substrate 40 may be 100 times or less of the first elastic modulus of the substrate 20. The method of calculating the third elastic coefficient of the support substrate 40 is the same as that of the substrate 20. In addition, the thickness of the support substrate 40 may be 500 nm or more.

[Electronic parts]
In the example shown in FIG. 1, the electronic component 51 at least includes an electrode connected to the wiring 52. The electronic component 51 may be an active component or a passive component. Examples of active components include transistors, large-scale integration (LSI), micro electro mechanical systems (MEMS), relays, light emitting elements such as LEDs, OLEDs, and LCDs, sensors, and the like. Examples of passive components include resistors, capacitors, inductors, and piezoelectric elements. Among the above-described examples of the electronic component 51, a sensor is preferably used. As a sensor, a temperature sensor, a pressure sensor, an optical sensor, a photoelectric sensor, a proximity sensor, a shear force sensor, a living body sensor etc. can be mentioned, for example. Of these sensors, biometric sensors are particularly preferred. The biological sensor can measure biological information such as heart rate, pulse, electrocardiogram, blood pressure, body temperature, blood oxygen concentration and the like. As shown in FIGS. 1 and 2, a plurality of electronic components 51 may be provided on the support substrate 40. Further, as shown in FIG. 1, the electronic component 51 may be covered by a sealing portion 58 made of resin or the like.

〔wiring〕
The wiring 52 is a conductive member connected to the electrode of the electronic component 51. For example, as shown in FIG. 2, one end and the other end of the wiring 52 are respectively connected to the electrodes of the two electronic components 51. As shown in FIG. 2, a plurality of wires 52 may be provided between two electronic components 51.

  As described later, when the tensile stress is removed from the substrate 20 bonded to the support substrate 40 and the substrate 20 contracts, the wiring 52 deforms in a bellows shape. Taking this point into consideration, preferably, the wiring 52 has a structure resistant to deformation. For example, the wire 52 has a base material and a plurality of conductive particles dispersed in the base material. In this case, the wiring 52 can also be deformed according to the expansion and contraction of the substrate 20 by using a deformable material such as a resin as the base material. In addition, the conductivity of the wiring 52 can be maintained by setting the distribution and the shape of the conductive particles so that the contact between the plurality of conductive particles is maintained even when deformation occurs. .

  For example, general thermoplastic elastomers and thermosetting elastomers can be used as the material constituting the base material of the wiring 52, and examples thereof include styrene-based elastomers, acrylic-based elastomers, olefin-based elastomers, urethane-based elastomers, and silicones. Rubber, urethane rubber, fluororubber, nitrile rubber, polybutadiene, polychloroprene and the like can be used. Among them, resins and rubbers having a urethane-based or silicone-based structure are preferably used in terms of their stretchability and durability. Moreover, as a material which comprises the electroconductive particle of the wiring 52, particle | grains, such as silver, copper, gold | metal | money, nickel, palladium, platinum, carbon, can be used, for example. Among them, silver particles are preferably used from the viewpoint of cost and conductivity.

  The thickness of the wiring 52 is smaller than the thickness of the electronic component 51, and is, for example, 50 μm or less. The width of the wiring 52 is, for example, 50 μm or more and 10 mm or less.

[Structure of wiring]
Subsequently, the sectional structure of the wiring 52 will be described in detail with reference to FIG. FIG. 3 is an enlarged cross-sectional view showing an example of the wiring 52 of the wiring substrate 10 shown in FIG. 1 and components therearound.

  As shown in FIGS. 1 and 2, the entire wiring 52 or most of the wiring 52 is disposed so as not to overlap with the stress adjustment mechanism 30 including the first reinforcing member 31 and the second reinforcing member 32. Therefore, the stress generated in the substrate 20 by the expansion and contraction of the substrate 20 is transmitted to the support substrate 40 and the wiring 52 on the support substrate 40. For example, when a tensile stress is removed from the substrate 20 in a stretched state to relax the substrate 20, a compressive stress is generated in the substrate 20 and this compressive stress is transmitted to the support substrate 40 and the wiring 52 on the support substrate 40. As a result, as shown in FIG. 3, the bellows-shaped portion 57 is formed in the portion of the wiring 52 not overlapping the stress adjustment mechanism 30.

  The bellows-shaped portion 57 includes peaks and valleys in the normal direction of the first surface 21 of the substrate 20. In FIG. 3, reference numeral 53 represents a peak portion appearing on the front surface of the wiring 52, and reference numeral 54 represents a peak portion appearing on the back surface of the wiring 52. Further, reference numeral 55 represents a valley appearing on the front surface of the wiring 52, and reference numeral 56 represents a valley appearing on the back surface of the wiring 52. The front surface is a surface located on the side far from the substrate 20 among the surfaces of the wiring 52, and the back surface is a surface located on the side closer to the substrate 20 among the surfaces of the wiring 52.

  The ridges 53 and 54 and the valleys 55 and 56 repeatedly appear along the in-plane direction of the first surface 21 of the substrate 20. The period F in which the peaks 53 and 54 and the valleys 55 and 56 appear repeatedly is, for example, 10 μm or more and 100 mm or less.

  In FIG. 3, reference symbol S 1 represents the amplitude of the bellows-shaped portion 57 on the surface 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 is easily deformed following the expansion of the substrate 20. The amplitude S1 may be, for example, 500 μm or less.

  The amplitude S1 measures, for example, the distance in the normal direction of the first surface 21 between adjacent peaks 53 and valleys 55 over a certain range in the lengthwise direction of the wiring 52, and the average Calculated by calculating. The “fixed range in the length direction of the wiring 52” is, for example, 10 mm. As a measuring device which measures the distance between the peak part 53 and the valley part 55 which adjoin, a non-contact-type measuring device using a laser microscope etc. may be used, and a contact-type measuring device may be used. . Further, based on an image such as a cross-sectional photograph, the distance between the adjacent ridges 53 and the valleys 55 may be measured.

  In FIG. 3, reference symbol S 2 represents the amplitude of the bellows-shaped portion 57 on the back surface of the wiring 52. The amplitude S2 is, for example, 1 μm or more, more preferably 10 μm or more, similarly to the amplitude S1. The amplitude S2 may be, for example, 500 μm or less.

  As shown in FIG. 3, a bellows-shaped portion similar to the wiring 52 may be formed on the support substrate 40, the adhesive layer 60 and the first surface 21 of the substrate 20. In FIG. 3, the symbol S 3 represents the amplitude of the bellows-shaped portion on the first surface 21 of the substrate 20. The amplitude S3 is, for example, 1 μm or more, and more preferably 10 μm or more. The amplitude S3 may be, for example, 500 μm or less.

  FIG. 4 is an enlarged cross-sectional view showing another example of the wiring 52 of the wiring substrate 10 shown in FIG. 1 and the components therearound. As shown in FIG. 5, the bellows-shaped portion may not be formed on the first surface 21 of the substrate 20.

  The advantage of the bellows 52 shown in FIGS. 3 and 4 being formed in the wiring 52 will be described. As described above, the substrate 20 has a modulus of elasticity of 10 MPa or less. Therefore, when tensile stress is applied to the wiring substrate 10, the substrate 20 can be elongated by elastic deformation. Here, if the wire 52 is similarly elongated by elastic deformation, the total length of the wire 52 increases and the cross-sectional area of the wire 52 decreases, so that the resistance value of the wire 52 increases. It is also conceivable that breakage such as a crack may occur in the wiring 52 due to the elastic deformation of the wiring 52.

  On the other hand, in the present embodiment, the wiring 52 has the bellows-shaped portion 57. Therefore, when the substrate 20 extends, the wiring 52 can follow the extension of the substrate 20 by deforming so as to reduce the unevenness of the bellows-shaped portion 57, that is, by eliminating the bellows shape. Therefore, it is possible to suppress an increase in the overall length of the wiring 52 and a reduction in the cross-sectional area of the wiring 52 as the substrate 20 expands. This can suppress an increase in the resistance value of the wiring 52 due to the expansion of the wiring substrate 10. In addition, it is possible to suppress the occurrence of damage such as a crack in the wiring 52.

  By the way, as shown in FIG. 3 and FIG. 4, a stress adjustment mechanism 30 including a first reinforcing member 31 and a second reinforcing member 32 is provided in a portion overlapping the electronic component 51 in the substrate 20. As described above, the first reinforcing member 31 and the second reinforcing member 32 have a high elastic modulus as compared to the substrate 20. Therefore, even after the substrate 20 is relaxed by removing the tensile stress from the substrate 20 in the stretched state, in the portion of the substrate 20 overlapping the first reinforcing member 31 and the second reinforcing member 32, the stretched state is at least partially partial. Maintained. As a result, as shown in FIGS. 3 and 4, the thickness T1 of the portion of the substrate 20 overlapping the first reinforcing member 31 and the second reinforcing member 32 is the first reinforcing member 31 or the second reinforcing member of the substrate 20. It becomes smaller than thickness T2 of the part which does not overlap with 32. For example, the thickness T1 is 50% or more and 95% or less of the thickness T2. When the bellows shape appears on the first surface 21 of the substrate 20 as shown in FIG. 3, the thickness T 2 can be calculated as an average value of the thickness of the substrate 20 within the range of the period F.

(Method of manufacturing wiring board)
Hereinafter, with reference to FIGS. 5A to 5E, a method of manufacturing the wiring substrate 10 will be described.

  First, a stretchable substrate 20 is prepared. Subsequently, as shown in FIG. 5A, a tensile stress T is applied to the substrate 20 to carry out a stretching step of stretching the substrate 20. The expansion rate of the substrate 20 is, for example, 10% or more and 200% or less. The stretching step may be performed in a state where the substrate 20 is heated, or may be performed at normal 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.

  Subsequently, a stress adjusting mechanism 30 is provided on the substrate 20 in a state of being stretched by the tensile stress T. Here, as shown in FIG. 5B, the first reinforcing member 31 is provided on the first surface 21 of the substrate 20, and the second reinforcing member 32 is provided on the second surface 22. The first reinforcing member 31 and the second reinforcing member 32 are provided so as to overlap each other when viewed along the normal direction of the first surface 21. In addition, the 1st reinforcement member 31 and the 2nd reinforcement member 32 may overlap over the whole area, and may overlap partially.

  Further, as shown in FIG. 5C, the support substrate 40 is prepared. In the present embodiment, as shown in FIG. 5C, the electronic component 51 and the wiring 52 are provided on the first surface 41 of the support substrate 40 in a state before being bonded to the substrate 20. As a method of providing the wiring 52, for example, a method of printing a conductive paste including a base material and conductive particles on the first surface 41 of the support substrate 40 can be employed.

  Subsequently, as shown in FIG. 5D, a bonding step of bonding the second surface 42 of the support substrate 40 provided with the electronic component 51 and the wiring 52 to the substrate 20 in a stretched state from the first surface 21 side. Conduct. The bonding step is performed such that the electronic component 51 mounted on the support substrate 40 overlaps the first reinforcing member 31 and the second reinforcing member 32 on the substrate 20. During the bonding process, an adhesive layer 60 may be provided between the substrate 20 and the support substrate 40.

  Thereafter, a contraction process is performed to remove the tensile stress T from the substrate 20. As a result, as shown by the arrow C in FIG. 5E, the substrate 20 shrinks, and the supporting substrate 40 and the wiring 52 bonded to the substrate 20 are also deformed. The third elastic modulus of the support substrate 40 is larger than the first elastic modulus of the substrate 20. Therefore, deformation of the support substrate 40 and the wiring 52 can be generated as the formation of the bellows-shaped portion.

  Further, in the present embodiment, the first reinforcing member 31 and the second reinforcing member 32 are provided on the substrate 20 in the extended state, and then the support substrate 40 is bonded to the substrate 20 in the extended state. For this reason, compared with the case where the first reinforcing member 31 and the second reinforcing member 32 are provided on the substrate 20 in the state before being stretched, the first reinforcing member 31 and the second It is easy to arrange the reinforcing member 32 with high accuracy. As a result, in the bonding step, the position of the electronic component 51 with respect to the first reinforcing member 31 and the second reinforcing member 32 can be prevented from shifting. Such an effect is remarkably exhibited when the plurality of electronic components 51 are mounted on the support substrate 40 and the alignment between the support substrate 40 and the substrate 20 is difficult.

  Further, in the present embodiment, the first reinforcing member 31 and the second reinforcing member 32 are provided on the substrate 20. Therefore, it is possible to suppress the relaxation of the portion of the substrate 20 overlapping the first reinforcing member 31 and the second reinforcing member 32 after removing the tensile stress from the substrate 20 in a stretched state. Therefore, the stress generated due to the relaxation of the substrate 20 is not easily transmitted to the portion of the support substrate 40 overlapping the first reinforcing member 31 and the second reinforcing member 32. For this reason, it is possible to suppress that the electronic component 51 on the support substrate 40 is deformed or damaged due to the stress. Furthermore, damage to the electrical connection between the electronic component 51 and the wiring 52 can be suppressed.

  As described above, according to the present embodiment, by providing the first reinforcing member 31 and the second reinforcing member 32 on the substrate 20, the positioning of the support substrate 40 and the substrate 20 can be easily performed, the electronic component 51 and the electronic The reliability of the electrical connection between the component 51 and the wiring 52 can be enhanced.

  An example of the effect on the resistance value of the wire 52 obtained by the bellows-shaped portion 57 of the wire 52 will be described. Here, the resistance value of the wiring 52 in the first state in which the tensile stress along the in-plane direction of the first surface 21 of the substrate 20 is not applied to the substrate 20 is referred to as a first resistance value. Further, the resistance value of the wiring 52 in a second state in which the substrate 20 is extended by 30% in the in-plane direction of the first surface 21 by applying a tensile stress to the substrate 20 is referred to as a second resistance value. . According to the present embodiment, by forming the bellows-shaped portion 57 in the wiring 52, the ratio of the absolute value of the difference between the first resistance value and the second resistance value to the first resistance value is made 20% or less. More preferably, it can be 10% or less, and more preferably, 5% or less.

  Examples of applications of the wiring substrate 10 include healthcare products, sports products, amusement products, vibration actuator devices, and the like. For example, a product attached to a part of the body such as a human arm is configured using the wiring board 10 according to the present 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 brought into close contact with a part of the body. Therefore, a good feeling of wearing can be realized. In addition, since it is possible to suppress a decrease in the resistance value of the wiring 52 when the wiring substrate 10 is extended, it is possible to realize good electrical characteristics of the wiring substrate 10.

  Note that various modifications can be made to the embodiment described above. Hereinafter, modifications will be described with reference to the drawings as needed. In the following description and the drawings used in the following description, with respect to parts that can be configured in the same manner as the embodiment described above, the same reference numerals as those used for the corresponding parts in the above embodiment are used. Duplicate descriptions will be omitted. In addition, in the case where it is clear that the effects and advantages obtained in the above-described embodiment can be obtained also in the modified example, the description may be omitted.

(First modification)
In the above-described embodiment, the first reinforcing member 31 and the second reinforcing member 32 are provided on the substrate 20 so as to maintain the extended state of the portion of the substrate 20 overlapping the electronic component 51, thereby providing the substrate 20 on the supporting substrate 40. An example has been shown in which the transfer of stress to the electronic component 51 is suppressed. In the present modification, an example in which the stress is prevented from being transmitted to the electronic component 51 on the support substrate 40 by relaxing the stress generated in the portion overlapping the electronic component 51 in the substrate 20 due to the extension. explain.

  FIG. 6 is a cross-sectional view showing a wiring board 10 according to the present modification. FIG. 7 is a bottom view showing the case where the wiring substrate 10 according to the present modification is viewed from the second surface 22 side of the substrate 20. As shown in FIG. The cross-sectional view shown in FIG. 6 is a view in which the wiring substrate 10 of FIG. 7 is cut along the line B-B.

  As shown in FIGS. 6 and 7, the stress adjusting mechanism 30 is formed on the second surface 22 of the substrate 20 so as to overlap the electronic component 51 when viewed along the normal direction of the first surface 21. The slit 33 is provided. For example, as shown in FIG. 7, the plurality of slits 33 are arranged along the direction in which the wiring 52 for producing the bellows-shaped portion 57 extends.

  FIG. 8 is an enlarged cross-sectional view showing an example of the wiring 52 of the wiring substrate 10 according to the present modification and the components therearound. Also in this modification, as in the case of the above-described embodiment, the bellows-shaped portion 57 is formed in the portion of the wiring 52 which does not overlap with the stress adjustment mechanism 30. Therefore, it is possible to suppress an increase in the overall length of the wiring 52 and a reduction in the cross-sectional area of the wiring 52 as the substrate 20 deforms.

  In FIG. 8, reference symbol T3 represents the depth of the slit 33. The depth T 3 of the slit 33 is the dimension of the slit 33 in the normal direction of the first surface 21, that is, in the thickness direction of the substrate 20. The depth T3 of the slit 33 is at least 10% or more, and may be 30% or more, of the thickness T2 of the portion of the substrate 20 where the slit 33 is not provided. In addition, the depth T3 of the slit 33 may be 90% or less of the thickness T2.

  FIGS. 9A to 9D are views for explaining the method of manufacturing the wiring board 10 according to the present modification.

  First, as shown in FIG. 9A, the substrate 20 is prepared. Subsequently, as shown in FIG. 9B, a tensile stress T is applied to the substrate 20 to carry out a stretching step of stretching the substrate 20. Subsequently, as shown in FIG. 9C, a bonding step of bonding the second surface 42 of the support substrate 40 provided with the electronic component 51 and the wiring 52 to the substrate 20 in a stretched state from the first surface 21 side. Conduct.

  Subsequently, as shown in FIG. 9D, a slit forming step is performed to form a plurality of slits 33 in the second surface 22 of the portion of the substrate 20 in the stretched state overlapping the electronic component 51 on the support substrate 40. . For example, the cutter is inserted into the substrate 20 from the second surface 22 side along the thickness direction of the substrate 20. As a result, the stress generated in the portion of the substrate 20 overlapping the electronic component 51 on the support substrate 40 can be relaxed.

  Thereafter, a contraction process is performed to remove the tensile stress T from the substrate 20. As a result, as shown by arrow C in FIG. 9E, the substrate 20 shrinks, and the supporting substrate 40 and the wiring 52 bonded to the substrate 20 are also deformed. The third elastic modulus of the support substrate 40 is larger than the first elastic modulus of the substrate 20. Therefore, deformation of the support substrate 40 and the wiring 52 can be generated as the formation of the bellows-shaped portion.

  Further, in the present modification, by forming the plurality of slits 33 in the substrate 20 as described above, the stress occurring in the portion of the substrate 20 overlapping the electronic component 51 on the support substrate 40 can be relaxed. it can. For this reason, it is possible to suppress that the electronic component 51 on the support substrate 40 is deformed or damaged due to the stress generated in the substrate 20. Furthermore, damage to the electrical connection between the electronic component 51 and the wiring 52 can be suppressed.

  Further, in the present modification, since the plurality of slits 33 are formed in the substrate 20 in the expanded state, compared to the case where the slits 33 are formed in the substrate 20 in the state before being expanded, electronic components of the substrate 20 It is easy to form the slit 33 in a place overlapping with 51 with high accuracy. By this, it can suppress that the position of the electronic component 51 with respect to the slit 33 shifts | deviates. Such an effect is remarkably exhibited when the plurality of electronic components 51 are mounted on the support substrate 40 and the alignment between the support substrate 40 and the substrate 20 is difficult.

(Modification of wiring board)
In the above-mentioned embodiment and each modification, the example in which the wiring board 10 was equipped with the electronic component 51 mounted in the 1st surface 21 side of the support substrate 40 was shown. However, the present invention is not limited to this, and the wiring substrate 10 may not have the electronic component 51. For example, the support substrate 40 in a state in which the electronic component 51 is not mounted may be bonded to the substrate 20. The wiring substrate 10 may be shipped in a state where the electronic component 51 is not mounted.

  Although some modifications to the above-described embodiment have been described, it is of course possible to apply a plurality of modifications in combination as appropriate.

  Next, the present invention will be more specifically described by way of Examples and Comparative Examples, but the present invention is not limited to the description of the following Examples as long as the gist thereof is not exceeded.

Example 1
As the wiring substrate 10, as shown in FIG. 1, a stress having a first reinforcing member 31 located on the first surface 21 of the substrate 20 and a second reinforcing member 32 located on the second surface 22 of the substrate 20. The one provided with the adjustment mechanism 30 was manufactured. Hereinafter, a method of manufacturing the wiring substrate 10 will be described.

<< Preparation of substrate and stress adjustment mechanism >>
An 80 μm thick urethane sheet was prepared which functions as the substrate 20. In addition, as the stress adjustment mechanism 30, a laminate having a copper foil having a square shape with one side of 5 mm and a thickness of 12 μm and an adhesive sheet laminated on the copper foil was prepared. As a pressure sensitive adhesive sheet, 8146 manufactured by 3M company was used. Subsequently, in a state in which the substrate 20 made of a urethane sheet is uniaxially stretched 1.5 times, the stress adjustment mechanism 30 made of a laminate is bonded to the first surface 21 and the second surface 22 of the substrate 20. At this time, the position was adjusted so that the stress adjusting mechanism 30 on the first surface 21 side, that is, the first reinforcing member 31 and the stress adjusting mechanism 30 on the second surface 22 side, that is, the second reinforcing member 32 overlap each other.

«Preparation of support substrate»
A 1 μm thick polyethylene naphthalate (PEN) film was prepared to serve as a support substrate 40. Subsequently, a conductive paste containing a solvent, a binder resin, and conductive particles was patterned on the first surface 41 of the support substrate 40 by screen printing. Diethylene glycol monoethyl ether acetate was used as a solvent. Urethane was used as a binder resin. Silver particles were used as the conductive particles. After patterning, annealing was performed in an oven at 80 ° C. for 30 minutes to volatilize the solvent to form the wiring 52. The wiring 52 was configured to be an electrode pair having a thickness of 20 μm, a line width of 100 μm, and an interval of 500 μm.

  Then, between the electrode pairs, an LED chip having a dimension of 1.0 × 0.5 mm was mounted using a conductive adhesive. As a conductive adhesive, CL-3160 manufactured by Riken Tech Co., Ltd. was used.

  Then, using the adhesive sheet 8146 manufactured by 3M, the support substrate 40 provided with the wiring 52 and the LED chip, and the substrate 20 provided with the stress adjustment mechanism 30 and stretched 1.5 times. I stuck it. At this time, the substrate 20 and the support substrate 40 were aligned so that the central portion of the square copper foil having a side of 5 mm of the stress adjustment mechanism 30 and the LED chip overlap each other.

  Then, the substrate 20 was released. As a result, in the region other than the region overlapping with the stress adjustment mechanism 30, a bellows-shaped portion is generated on the surface of the wiring 52, and the wiring substrate 10 is contracted. At this time, the conductive connection of the LED chip was maintained, and the LED chip continued to light.

(Example 2)
As the wiring substrate 10, one provided with a stress adjusting mechanism 30 having a plurality of slits 33 formed on the second surface 22 of the substrate 20 as shown in FIG. 6 was manufactured. Hereinafter, a method of manufacturing the wiring substrate 10 will be described.

  First, an 80 μm-thick urethane sheet which functions as the substrate 20 was prepared. Further, in the same manner as in Example 1, a supporting substrate 40 provided with the wiring 52 and the LED chip was prepared. Subsequently, in a state in which the substrate 20 made of a urethane sheet is uniaxially stretched 1.5 times, the support substrate 40 and the substrate 20 are bonded together using an adhesive sheet 8146 manufactured by 3M company.

  Subsequently, a plurality of slits 33 were formed on the surface of the substrate 20 opposite to the support substrate 40, that is, the second surface 22, using a cutting plotter. As a cutting plotter, GRAPHTEC's FC2250 was used. The pattern of the slits 33 was a grid of five slits 33 orthogonal to each other. The width of the slits 33 was 5 mm, and the distance between the slits 33 was 1 mm. Moreover, the slit 33 was formed so that the center part of the area | region in which several grid-like slits 33 of gridboard exist, and LED chip might overlap.

  Then, the substrate 20 was released. As a result, in the area other than the area overlapping with the stress adjusting mechanism 30 formed by the grid-like slits 33, a bellows-shaped portion is generated on the surface of the wiring 52, and the wiring board 10 is shrunk. At this time, the conductive connection of the LED chip was maintained, and the LED chip continued to light.

(Comparative example 2)
A wiring board 10 was produced in the same manner as in Example 1 except that the stress adjustment mechanism 30 was not provided. In this case, when the wiring substrate 10 is contracted after releasing the extension of the substrate 20, the conductive connection of the LED chip is disconnected as the wiring substrate 10 is contracted, and the LED is not lit.

DESCRIPTION OF REFERENCE NUMERALS 10 wiring substrate 20 substrate 21 first surface 22 second surface 30 stress adjusting mechanism 31 first reinforcing member 32 second reinforcing member 33 slit 40 supporting substrate 41 first surface 42 second surface 51 electronic component 52 wiring 53, 54 peak portion 55, 56 valley portion 57 bellows shaped portion 58 sealing portion 60 adhesive layer

Claims (11)

A stretchable substrate including a first surface and a second surface opposite to the first surface;
A support substrate bonded to the substrate from the first surface side of the substrate and having a modulus of elasticity higher than that of the substrate;
A wire provided on the support substrate so as to be connected to an electrode of an electronic component mounted on the support substrate, wherein a peak portion and a valley portion in the normal direction of the first surface of the substrate are the above-mentioned substrate A wire having a bellows-shaped portion that repeatedly appears along the in-plane direction of the first surface;
A wiring board, comprising: a stress adjusting mechanism provided on a part of the substrate to suppress transfer of a stress generated on the substrate due to expansion and contraction to the support substrate.   The stress adjustment mechanism is positioned on the first surface of the substrate so as to overlap the electronic component mounted on the support substrate when viewed along the normal direction of the first surface, and the elastic modulus of the substrate A first reinforcing member having a higher elastic modulus than the first surface of the substrate so as to overlap the electronic component mounted on the support substrate when viewed along the normal direction of the first surface And a second reinforcing member having a modulus of elasticity higher than that of the substrate.   The thickness of the portion of the substrate overlapping the first reinforcing member and the second reinforcing member when viewed along the normal direction of the first surface is the normal direction of the first surface of the substrate. The wiring substrate according to claim 2, wherein the wiring substrate is smaller than a thickness of a portion not overlapping with the first reinforcing member or the second reinforcing member when viewed along the line.   The wiring substrate according to claim 2, wherein the first reinforcing member and the second reinforcing member include a metal layer.   The stress adjustment mechanism includes a plurality of slits formed on the second surface of the substrate so as to overlap the electronic component mounted on the support substrate when viewed along the normal direction of the first surface. The wiring board according to claim 1.   The wiring board according to any one of claims 1 to 5, wherein the amplitude of the bellows-shaped portion of the wiring is 1 μm or more.   The wiring board according to any one of claims 1 to 6, wherein the substrate comprises silicone rubber.   The wiring board according to any one of claims 1 to 7, wherein the wiring includes a plurality of conductive particles.   The wiring board according to any one of claims 1 to 8, further comprising an electronic component having an electrode located on the support substrate and electrically connected to the wiring. A method of manufacturing a wiring substrate,
A stretching step of stretching the substrate by applying a tensile stress to the substrate having a first surface and a second surface opposite to the first surface, the substrate having elasticity;
A first reinforcing member having a modulus of elasticity higher than that of the substrate is provided on the first surface of the substrate, and a second reinforcing member having a modulus of elasticity higher than that of the substrate is the second reinforcing member of the substrate. Providing on two sides,
The support substrate having a modulus of elasticity higher than that of the substrate, wherein the support substrate provided with a wiring connected to the electrodes of the electronic component mounted on the support substrate is extended to the substrate in a stretched state A bonding step of bonding from the first surface side,
And d) removing the tensile stress from the substrate.
The bonding step is performed such that the electronic component mounted on the support substrate overlaps the first reinforcing member and the second reinforcing member when viewed along the normal direction of the first surface.
After the tensile stress is removed from the substrate, the portion of the wiring which does not overlap the first reinforcing member and the second reinforcing member when viewed along the normal direction of the first surface is the first wiring. A manufacturing method of a wiring board which has a bellows shape part which a peak part and a valley part in the direction of a normal of 1 face repeatedly appear along an in-plane direction of the 1st field. A method of manufacturing a wiring substrate,
A stretching step of stretching the substrate by applying a tensile stress to the substrate having a first surface and a second surface opposite to the first surface, the substrate having elasticity;
The support substrate having a modulus of elasticity higher than that of the substrate, wherein the support substrate provided with a wiring connected to the electrodes of the electronic component mounted on the support substrate is extended to the substrate in a stretched state A bonding step of bonding from the first surface side,
And d) removing the tensile stress from the substrate.
The second surface of the portion of the substrate overlapping the electronic component mounted on the support substrate when viewed along the normal direction of the first surface, which is performed between the bonding step and the contraction step. Further comprising a slit forming step of forming a plurality of slits in the
After the tensile stress is removed from the substrate, a portion of the wire which does not overlap with the slit when viewed along the normal direction of the first surface is a peak portion in the normal direction of the first surface. And a method of manufacturing the wiring substrate, wherein the valley portion has a bellows-shaped portion that repeatedly appears along the in-plane direction of the first surface.