Manufacturing method for conductive patterned substrates

Abstract

One aspect of the present invention relates to a method for manufacturing a substrate with a conductive pattern attached thereto, the method comprising: a base forming step for forming, on at least a portion of one surface of a stretchable substrate, a plating base in a desired pattern, the stretchable substrate having a tensile modulus at 20 °C of 0.1 MPa to 500 MPa, an elongation at break of 100% to 1,000%, and a storage modulus at 250 °C of at least 0.1 MPa; a bending step for bending the stretchable substrate; and a conductive pattern forming step for forming a conductive pattern on the stretchable substrate by plating the plating base, after performing the bending step.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a substrate with a conductive pattern, particularly a method for manufacturing a substrate with a conductive pattern having a curved surface.

Background Art

[0002] In the field of electronics, particularly for devices and conductive materials used in various interfaces such as sensors, displays, and artificial skin for robots, the requirements for wearability and shape followability are increasing. Flexible devices that can be arranged on curved surfaces, uneven surfaces, etc. or freely deformed according to the application are being demanded.

[0003] On the other hand, methods for forming circuits and wirings on three-dimensional objects having curved surfaces have also been studied. For example, in Patent Document 1, a preparation step of preparing a resin film having an elongation at break of 50% or more, a first metal film formation step of forming a first metal film on the surface of the resin film, a pattern formation step of patterning the first metal film by photolithography to form a desired pattern, a three-dimensional molding step of performing heating and pressure on the resin film for three-dimensional molding, and a second metal film formation step of forming a second metal film on the patterned first metal film are provided. In the first metal film formation step, a method for manufacturing a three-dimensional wiring substrate in which the first metal film is formed in a porous state by depositing metal in a particulate state and adjusting the film thickness is disclosed.

[0004] Furthermore, Patent Document 2 discloses a method for manufacturing a three-dimensional conductive pattern structure having a conductive pattern formed on the surface of a three-dimensional structure, comprising the following steps a) to d): a) a modified pattern formation step of printing a pattern on the surface of a polyimide resin material having at least a part of the surface of a polyimide resin using a modifier to produce a three-dimensional moldable material having a modified pattern in which the imide ring is cleaved; b) a plating catalytic activity pattern formation step of producing a three-dimensional moldable material having a pattern having plating catalytic activity by adsorbing metal ions having plating catalytic activity onto the pattern formation portion of the three-dimensional moldable material obtained in step a) and then reducing the metal ions; c) a three-dimensional molding process of manufacturing a three-dimensional structure having a pattern having plating catalytic activity by three-dimensional molding the three-dimensional moldable material obtained in step b) having a pattern having plating catalytic activity; and d) an electroless plating step of manufacturing a three-dimensional conductive pattern structure by applying electroless plating treatment to the three-dimensional structure having a pattern having plating catalytic activity obtained in step c) to form a conductive pattern.

[0005] However, the technologies described in Patent Documents 1 and 2 above both use polyimide resin as the base material, which has the drawback of requiring a large amount of energy in the three-dimensional molding process. Furthermore, the flexibility is not sufficient, and if the material to be circuit-formed is made of a soft material, there is a risk of damaging the shape and feel of the material to be circuit-formed, or of the circuit breaking due to stretching and contracting movements.

[0006] This invention has been made in view of the above circumstances, and aims to provide a method for manufacturing a circuit board that can easily form circuits and wiring that are resistant to breakage on a three-dimensional structure (circuit-forming body) having irregularities (bent parts). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2016 / 208090 [Patent Document 2] International Publication No. 2014 / 168220 [Overview of the project]

[0008] As a result of diligent research, the inventors found that the above problems could be solved by the following configuration, and based on this finding, they completed the present invention through further research.

[0009] In other words, a method for manufacturing a conductive patterned substrate relating to one aspect of the present invention is: A base preparation step of forming a plating base in a desired pattern on at least a portion of one side of a stretchable substrate having a tensile modulus of 0.1 MPa or more and 500 MPa or less at 20°C, a breaking elongation of 100% or more and 1000% or less, and a storage modulus of 0.1 MPa or more at 250°C, A bending step of bending the aforementioned stretchable substrate, The method is characterized by including a conductive pattern forming step, after the bending step, in which plating is applied to the plating base to form a conductive pattern on the stretchable substrate. Furthermore, a method for manufacturing a conductive patterned substrate relating to another aspect of the present invention is: A substrate forming step of forming a plating substrate on at least a portion of one side of a stretchable substrate having a tensile modulus of 0.1 MPa or more and 500 MPa or less at 20°C, a breaking elongation of 100% or more and 1000% or less, and a storage modulus of 0.1 MPa or more at 250°C, A bending step of bending the aforementioned stretchable substrate, After the bending process, a metal layer forming process is performed, in which plating is applied to the plating substrate to form a metal layer. The method is characterized by including a conductive pattern forming step of etching the metal layer to form a conductive pattern. [Brief explanation of the drawing]

[0010] [Figure 1]Figure 1 is a schematic cross-sectional view showing a method for manufacturing a conductive patterned substrate according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic cross-sectional view showing a method for manufacturing a conductive patterned substrate according to another embodiment of the present invention. [Modes for carrying out the invention]

[0011] (Manufacturing method for conductive patterned substrates) The manufacturing method for a conductive patterned substrate of this embodiment is characterized by comprising: a base forming step of forming a plating base in a desired pattern on at least a part of one side of a stretchable substrate (hereinafter also simply referred to as "substrate") having a tensile modulus of elasticity of 0.1 MPa or more and 500 MPa or less at 20°C, a breaking elongation of 100% or more and 1000% or less, and a storage modulus of elasticity of 0.1 MPa or more at 250°C; a bending step of bending the stretchable substrate; and a conductive pattern forming step of forming a conductive pattern on the stretchable substrate by applying plating on the plating base after the bending step.

[0012] According to the above configuration, it is possible to provide a method for manufacturing a conductive patterned substrate that can easily form circuits, wiring, heating wires, etc., on a three-dimensional structure (conductive pattern forming body) having irregularities (bent parts) and is resistant to breakage.

[0013] The present invention will be described in more detail below with reference to the drawings and other information, but the present invention is not limited to these.

[0014] (substrate) First, the substrate used in this embodiment will be described. The substrate used in this embodiment is a stretchable substrate having a tensile elastic modulus of 0.1 MPa or more and 500 MPa or less at 20°C, an elongation at break of 100% or more and 1000% or less, and a storage elastic modulus of 0.1 MPa or more at 250°C. The substrate of this embodiment has flexibility even at room temperature and can follow the unevenness of a three-dimensional shape, so it is possible to form a substrate with a conductive pattern on various-shaped objects having bent portions or the like. Further, even if the object is a soft material, the shape and touch of the object to be formed with the conductive pattern are not impaired, and the resulting circuit, wiring, heating wire, etc. are also strong against breakage, for example, the circuit or the like is not broken by stretching and contracting operations.

[0015] In this embodiment, for the tensile elastic modulus, a sample cut into a size of 90 mm * 5.5 mm was attached to a universal testing machine (AGS-X manufactured by Shimadzu Corporation), and the test was performed at a tensile speed of 500 mm / min, and the tensile elastic modulus was calculated from the stress from an elongation rate of 1.0% to 5.0%.

[0016] A more preferable range of the tensile elastic modulus in the substrate of this embodiment is 1.0 MPa or more and 100 MPa or less. Thereby, there are advantages that the handling property of the substrate is good and it has sufficient followability to unevenness.

[0017] Further, since the substrate of this embodiment has an elongation at break of 100% or more and 1000% or less, it is possible to suppress breakage when the substrate is laminated on the bent portions of the three-dimensional structure and the mold described later. The elongation at break is an index (elongation rate) indicating the flexibility in this embodiment. A sample cut from the substrate sample into a size of 90 mm * 5.5 mm was attached to a universal testing machine (AGS-X manufactured by Shimadzu Corporation), and the test was performed at a tensile speed of 500 mm / min, and the elongation rate when the sample broke was measured by the tester.

[0018] Furthermore, the substrate of the present embodiment has a storage elastic modulus of 0.1 MPa or more at 250°C. Thereby, the substrate can ensure sufficient heat resistance and is excellent in component mounting property without being deteriorated when mounting components. The storage elastic modulus in the present embodiment is a value that can be measured by the method described in the examples below.

[0019] The substrate of the present embodiment is not particularly limited as long as it is composed of a material such that the tensile elastic modulus, elongation at break, and storage elastic modulus are within the above ranges. For example, it preferably contains a thermosetting resin. By including a thermosetting resin in the substrate of the present embodiment, it exhibits high heat resistance. For example, it can be made into a substrate that is less likely to melt or thermally decompose even in a high-temperature atmosphere when mounting electronic components.

[0020] As the thermosetting resin, a thermosetting resin generally used as an insulating layer of an electronic base material can be used.

[0021] The substrate of the present embodiment is preferably formed of, for example, a cured product or semi-cured product of a resin composition containing a thermosetting resin. However, the resin composition is not particularly limited in terms of its composition as long as the tensile elastic modulus of the substrate at 20°C is within the above range.

[0022] For example, the resin composition of the present embodiment preferably contains an epoxy resin as a thermosetting resin. Furthermore, it preferably contains a curing agent. Thereby, a substrate having sufficient heat resistance and capable of withstanding the heat during component mounting in a reflow process can be obtained. Also, by curing the uncured resin composition after laminating it with the conductive pattern forming body described below, it becomes easy to integrate the substrate with the conductive pattern forming body without using an adhesive or the like.

[0023] Examples of the thermosetting resin include, in addition to epoxy resins, thermosetting resins such as phenolic resins, polyimide resins, urea resins, melamine resins, unsaturated polyesters, and urethane resins without particular limitation. Among these, it is preferable to use an epoxy resin.

[0024] Examples of the epoxy resins mentioned above include, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, aralkyl epoxy resin, phenol novolac type epoxy resin, alkylphenol novolac type epoxy resin, biphenol type epoxy resin, naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, epoxidized products of condensates of phenols and aromatic aldehydes having phenolic hydroxyl groups, triglycidyl isocyanurate, and alicyclic epoxy resins. Depending on the situation, one of these may be used alone, or two or more may be used in combination.

[0025] More preferably, the epoxy resin is one which contains two or more epoxy groups in a single molecule and has a molecular weight of 500 or more. Commercially available epoxy resins may be used as such, and examples include JER1003 (manufactured by Mitsubishi Chemical, molecular weight 1300, bifunctional), EXA-4816 (manufactured by DIC, molecular weight 824, bifunctional), YP50 (manufactured by Nippon Steel Sumitomo Metal Chemical, molecular weight 60000-80000, bifunctional), and PMS-14-67 (manufactured by Nagase ChemteX, molecular weight 300000, polyfunctional). Furthermore, one type of epoxy resin may be used alone, or two or more types may be used in combination.

[0026] As for the curing agent, there are no particular restrictions as long as it acts as a curing agent for thermosetting resins as described above.

[0027] In particular, examples of curing agents that can be preferably used for epoxy resins include phenolic resins, amine compounds, acid anhydrides, imidazole compounds, sulfide resins, and dicyandiamides. Light- and ultraviolet curing agents and thermal cationic curing agents can also be used. These may be used individually or in combination of two or more, depending on the situation. Furthermore, the resin composition may contain a curing accelerator as needed. Examples of such curing accelerators include imidazole compounds.

[0028] If the resin composition of this embodiment contains an epoxy resin, it is preferable that the total amount of the resin composition be 100 parts by mass, with the epoxy resin being approximately 50 to 99 parts by mass. The amount of curing agent can be appropriately set depending on the number of functional groups of epoxy in the epoxy resin.

[0029] Furthermore, the resin composition may optionally contain other additives, such as curing catalysts (curing accelerators), flame retardants, flame retardant aids, leveling agents, colorants, etc., to the extent that they do not impair the effects of the present invention.

[0030] There are no particular limitations on the method for preparing such a resin composition. For example, the resin composition of this embodiment can be obtained by first uniformly mixing an epoxy resin, a curing agent, a crosslinking agent, a thermosetting resin, and a solvent. There are no particular limitations on the solvent used. For example, toluene, xylene, methyl ethyl ketone, acetone, etc., can be used. These solvents may be used individually or in combination of two or more. In addition, organic solvents for adjusting viscosity and various additives may be added as needed.

[0031] The substrate of this embodiment is obtained, for example, by partially curing (stage B) or fully curing (stage C) the resin composition described above. The timing of partial curing or full curing may be after lamination with the conductive pattern forming body described later, before lamination, or before forming the substrate.

[0032] Specifically, for example, the substrate of this embodiment can be formed by preparing a resin varnish containing an organic solvent from the resin composition described above, applying the resin varnish to the surface of a desired plastic film (support), and then drying it. The method of applying the resin composition is not particularly limited, but examples include bar coaters, comma coaters, die coaters, roll coaters, gravure coaters, etc.

[0033] After applying the resin varnish, heating can cause the organic solvent to volatilize from the resin layer (Stage A) containing the uncured resin composition with an organic solvent, thereby reducing or removing the organic solvent. When the applied resin varnish is heated under desired heating conditions, for example, 80-120°C for 1-120 minutes, an uncured or semi-cured substrate (Stage B) with reduced or removed organic solvent is obtained. In this embodiment, Stage B of the resin composition, i.e., the uncured state (uncured material) or semi-cured state (semi-cured material), refers to a state in which the resin composition can be further cured. For example, when a resin composition is heated, its viscosity gradually decreases at first, then curing begins, and the viscosity gradually increases. In such a case, a semi-cured state would be the state between when the viscosity begins to increase and when it is not yet completely cured.

[0034] Further heating can cure the substrate. The applied resin composition (resin varnish) is heated under desired heating conditions, for example, 80-200°C for 1-120 minutes, to obtain a substrate in a cured state (C stage). In this embodiment, the C stage of the resin composition, i.e., the cured state (cured product), refers to a state in which the curing reaction has progressed and the resin has crosslinked, so that it does not melt even when heated.

[0035] When laminating the film-like resin composition to a conductive pattern-forming body, for example, the resin composition may be pre-coated onto a desired plastic film (support), and a resin layer containing the resin composition before curing (Stage A) containing an organic solvent may be formed on the film, or an uncured or semi-cured (Stage B) resin layer may be formed by heating under desired heating conditions, for example, 80 to 120°C for 1 to 120 minutes. Further heating may cure the resin to a cured (Stage C) substrate.

[0036] (First Embodiment) Next, an embodiment of the method for manufacturing a conductive patterned substrate of the present invention, using the substrate described above, will be explained with reference to Figure 1. In this specification, each reference numeral in the drawings indicates the following: 1 substrate, 2 plating underlayment, 3 plating (metal layer), 4 three-dimensional structure (conductive pattern forming body), 5 mold, and 6 release liner.

[0037] First, as shown in Figure 1(A), a stretchable substrate 1 is prepared having a tensile modulus of 0.1 MPa to 500 MPa at 20°C, an elongation at break of 100% to 1000%, and a storage modulus of 0.1 MPa or more at 250°C, and a plating base 2 is formed on one surface of the substrate (base formation step). Next, as shown in Figure 1(B), the substrate 1 with the plating base 2 is bent (bending step). Then, as shown in Figure 1(C), a conductive pattern is formed on the stretchable substrate by applying plating 3 on top of the plating base 2 on the stretchable substrate that has been bent in the bending step (conductive pattern formation step). In the bending step, the plating base 2 follows the bent shape together with the substrate, and then plating 3 is formed on top of the plating base 2, so there is no risk of disconnection of circuits, etc., obtained by the conductive pattern. The conductive pattern formed in this embodiment can be used as a circuit or wiring, and can also be used as, for example, a heating wire (resistance wire) for a heater.

[0038] In this embodiment of the method for manufacturing a conductive patterned substrate, a desired circuit pattern can be easily formed on the curved surface of a three-dimensional structure. According to the method of this embodiment, even if the three-dimensional structure is made of a soft material, the shape and feel of the conductive patterned body are not impaired, and the resulting circuits are highly resistant to breakage, for example, they will not break due to stretching or contracting movements.

[0039] Further details of each step in the first embodiment will be described.

[0040] (base formation process) The plating underlayment formation process is a process of forming a plating underlayment in a desired pattern on at least a portion of one side of the substrate as described above. This plating underlayment forms a conductive pattern on the substrate according to the desired shape of circuits, wiring, heating elements, etc. The plating underlayment may be formed when the substrate is stretched or before stretching (in its normal state).

[0041] In this embodiment, the formation of the plating substrate refers to depositing the plating catalyst described above onto the surface of the substrate. Here, the term "plating catalyst" is a concept that includes its precursor.

[0042] The plating catalyst is a catalyst that is applied in advance to form a plating film (electroless plating film) only on the parts where plating is desired in the conductive pattern formation process described later. Any known electroless plating catalyst can be used as the plating catalyst. Alternatively, a precursor of the plating catalyst may be applied beforehand, and then the plating catalyst may be generated. Specific examples of plating catalysts include, for example, metallic palladium (Pd), platinum (Pt), silver (Ag), gold (Au), nickel (Ni), cobalt (Co), iron (Fe), and precursors that generate these. Among these, it is preferable to use palladium, which has high catalytic activity.

[0043] One example of a method for depositing a plating catalyst is to treat the material with an acidic Pd-Sn colloidal solution under acidic conditions of pH 1-3, followed by treatment with an acidic solution. Known acidic Pd-Sn colloidal catalyst solutions can be used as the acidic catalyst metal colloidal solution, and commercially available plating processes using acidic catalyst metal colloidal solutions may also be used. Such processes are commercially available as systems from companies such as Rohm & Haas Electronic Materials.

[0044] Through this catalyst deposition process, as shown in Figure 1(A), a plating catalyst can be deposited on the surface of the substrate 1, forming a plating base 2.

[0045] Alternatively, a plating base can be formed by printing a desired pattern onto the substrate using a catalytic ink consisting of the plating catalyst described above, by known means.

[0046] Although the above description primarily assumes electroless plating, the plating in this embodiment may also involve electrolytic plating in addition to electroless plating.

[0047] The plating undercoat may be formed only on at least a portion of the substrate, i.e., only on the area where circuits and wiring are to be formed, but it can also be formed on the entire surface of the substrate. In that case, the plating catalyst is applied to the entire surface of one side of the substrate, or the entire surface is printed with catalyst ink. After that, a metal layer is formed on the entire surface by plating, and then the metal layer is etched using the etching process described later, leaving the desired pattern of circuits and wiring, thereby forming the circuits and wiring.

[0048] (bending process) Next, the substrate on which the plating base has been formed is bent. In the first embodiment, this bending process can be carried out using a conductive pattern forming body (three-dimensional structure) that has a bend. That is, as shown in Figure 1(B), the substrate 1 is bent by stacking the substrate 1 on the bent portion of the conductive pattern forming body 4.

[0049] In this embodiment, the conductive pattern-forming body, which is the object on which the conductive pattern is formed, is not particularly limited as long as it has a bent portion. In other words, in this embodiment, at least a part of the conductive pattern-forming surface on which the conductive pattern is formed is bent. Specific conductive pattern-forming materials include, for example, plastics and rubber and products thereof, leather and fur and products thereof, animal accessories and travel gear, handbags and other similar containers and intestine products, wood and its products, charcoal, cork and its products and products of straw, esparto and other woven materials and basketry and branchwork, wood pulp, other pulps made from cellulose fibers, recycled paper and paper and cardboard and products thereof, textile fibers and their products, footwear, hats, umbrellas, canes, sheet walking sticks and whips and parts thereof, prepared feathers, feather products, artificial flowers and human hair products, stone, plaster, cement, asbestos, mica and other similar materials and products thereof, ceramic products and glass and its products, natural or cultured pearls, precious stones, semi-precious stones, precious metals and metals clad in precious metals and these Examples include products, counterfeit coins and currency, base metals and their products, machinery and electrical equipment and their parts, sound recorders, sound players and television equipment for recording or playing images and sounds and their parts and accessories, vehicles, aircraft, ships and transportation equipment, optical instruments, photographic equipment, cinematography equipment, measuring instruments, inspection equipment, precision instruments, medical equipment, watches and musical instruments and their parts and accessories, furniture, bedding, mattresses, mattress supports, cushions and other similar stuffed articles, lamps and other lighting fixtures (excluding those falling under other categories), illumination signs, luminous nameplates and other similar articles, and prefabricated buildings, toys, games and sports equipment and their parts and accessories, as well as three-dimensional structures with curved parts. According to the manufacturing method of conductive patterned substrates of this embodiment, circuits and the like can be formed even in such complex shapes (shapes with curved parts) without using molds or the like.

[0050] In this embodiment, even if the conductive pattern forming body is a three-dimensional structure having a bent portion, by using a flexible substrate on which a plating base has been formed, desired circuits, wiring, etc. can be easily formed on the conductive pattern forming body without using a mold or the like, as shown in Figure 1(B). Furthermore, even if the flexible substrate stretches to follow the bent portion of the conductive pattern forming body, the subsequent plating is not significantly affected even if the plating base, consisting of a plating catalyst or catalytic ink, stretches, so that the circuits, wiring, etc., formed by the plating later do not break.

[0051] There are no particular limitations on the means of laminating the substrate onto the bent portion of the conductive pattern forming body. This can be done by bonding the side of the substrate that does not have a plating base to at least a part or the entire surface of the bent portion. If the substrate contains a thermosetting resin, there is no need to use an adhesive for bonding. By laminating the substrate in stage B and allowing the curing reaction to reach stage C, the substrate and the conductive pattern forming body having the bent portion can be laminated with excellent adhesion.

[0052] In the bending process of this embodiment, it is preferable to laminate a substrate onto the conductive pattern forming body and bend it, while simultaneously integrating the conductive pattern forming body and the substrate.

[0053] (Pre-plating treatment process) Furthermore, although not shown in the figures, this embodiment may include, if necessary, a pre-plating treatment step to expose the plating catalyst to the surface before the plating process described later. This pre-plating treatment step allows the plating process to be carried out properly. The specific pre-treatment is not particularly limited, but examples include immersing the laminate of the substrate and the conductive pattern forming body obtained above in a resin swelling solution.

[0054] (Conductive pattern formation process) Next, as shown in Figure 1(C), a plating process is applied to the laminate of the substrate 1 and the conductive pattern forming body 4 to form a plating 3 on the plating base 2 and create a conductive pattern.

[0055] As an example of a plating process, we will describe a process using electroless plating.

[0056] First, by performing electroless plating on the laminate, an electroless plating film is deposited on the portion of the substrate where the plating base has been formed, and this electroless plating film becomes the plating of this embodiment.

[0057] One possible method of electroless plating involves immersing a substrate with a partially formed plating base in an electroless plating solution, thereby depositing an electroless plating film only on the areas where the plating base has been formed.

[0058] Examples of metals used in electroless plating include copper (Cu), nickel (Ni), cobalt (Co), and aluminum (Al). Of these, plating with Cu as the main component is preferred due to its excellent conductivity. Furthermore, plating containing Ni is preferred due to its excellent corrosion resistance and adhesion to solder.

[0059] In this embodiment, the thickness of the plating, which is composed of an electroless plating film, is not particularly limited and can be set as desired.

[0060] In the case of electroplating, the electroplating process is performed after the aforementioned electroless plating process to form the plating and create the desired conductive pattern.

[0061] (Etching process) Although not shown in Figure 1, the conductive pattern formation method of this embodiment may further include an etching step.

[0062] In the etching process, the excess plating film (unnecessary overflow portion) formed by the conductive pattern formation (plating process) described above is removed by etching, thereby forming a conductive pattern by plating.

[0063] Specifically, first, the amount of excess or removal of unwanted plating film is measured. For example, the height of the excess plating protruding from the substrate surface is measured using an OLYMPUS LEXT OLS3000 scanning confocal laser microscope. Based on the measured amount, the amount to be etched is determined, and the etching process is performed. The etching process is not particularly limited, but can be carried out using an etching agent.

[0064] In this embodiment, the etching agent is preferably an alkaline etching agent. Specifically, an alkaline etching agent containing an amine compound as the main component, and at least hydrogen peroxide and sulfuric acid, can be used. It is believed that by using such an etching agent, the plating film on the over-plated portion can be removed efficiently and easily. The etching agent is preferably further containing an organic acid. Furthermore, it is preferable that the etching solution is a micro-etching solution.

[0065] The etching process in this embodiment can be carried out, for example, by spraying the etching agent described above onto the substrate. The spraying conditions are not particularly limited as long as the over-plated areas are treated without excess or deficiency.

[0066] This etching process removes excess or unnecessary plating, allowing for the formation of highly reliable circuits and other components.

[0067] Alternatively, if the plating substrate is applied to the entire surface of the substrate in the plating substrate formation process described above, the etching process can be used to form circuits, etc., by etching away all unnecessary parts except for the plating that will form the conductive pattern. In this case, after the bending process, a plating process is performed to form a metal layer on the plating substrate (metal layer formation process), and then this metal layer is etched in the etching process to form circuits, etc., with the desired pattern (conductive pattern formation process by etching).

[0068] (Component mounting process) The manufacturing method of this embodiment may further include a step of mounting electronic components after forming the conductive pattern. The substrate of this embodiment exhibits excellent heat resistance, making it excellent for component mounting and able to withstand the heating of soldering and reflow processes.

[0069] There are no particular limitations on the components that can be implemented, and examples include various electronic components such as LED elements, passive elements, active elements, integrated circuits, displays, motors, speakers, piezoelectric elements, switches, fuses, antennas, heat sinks, accelerometers, temperature sensors, humidity sensors, light sensors, ultrasonic sensors, pH sensors, gas sensors, motion sensors, angle sensors, magnetic sensors, gyroscopes, pressure sensors, compass sensors, radiation sensors, sound sensors, GPS receivers, and batteries.

[0070] The method for mounting electronic components on the conductive pattern is not particularly limited and includes methods such as using a soldering iron, applying various types of solder paste, mounting the electronic components using various component mounting devices, and then mounting them using various reflow devices. In particular, it is preferable to use means to heat only the metal parts using induction heating, microwaves, etc.

[0071] As described above, the conductive pattern formation method of this embodiment allows for the formation of conductive patterns on three-dimensional structures with irregularities (bent surfaces) while suppressing wire breakage, using a metal material (plating or metal layer used to form circuits, wiring, heating elements, etc.) that has high conductivity but poor elasticity. Furthermore, since the substrate of this embodiment is flexible even at room temperature, the use of molds is not essential, and conductive patterns can be formed by laminating it onto bent sections. In other words, in this embodiment, even if the three-dimensional structure is a non-conductive pattern-forming body, the substrate can be laminated onto the non-conductive pattern-forming body to form a conductive pattern, and the substrate can be integrated as is. In addition, even if the non-conductive pattern-forming body is flexible, there is the advantage that its flexibility is not impaired after the conductive pattern is formed.

[0072] Therefore, the conductive pattern formation method of this embodiment is extremely useful for industrial applications because it can easily form circuits, wiring, heating elements, etc., on three-dimensional structures having irregularities (bent sections), and does not impair the flexibility of the three-dimensional structure.

[0073] (Second embodiment) As described above, the present invention's method for manufacturing conductive patterned substrates does not require the use of a mold, and conductive patterned substrates with bent portions can be manufactured without using a mold. However, it is also possible to manufacture them using a mold. Advantages of using a mold include improved productivity and the ability to form fine irregularities (bent portions).

[0074] A method for manufacturing a conductive patterned substrate using a mold, according to the second embodiment, will be explained with reference to Figure 2. In the conductive patterned substrate according to the second embodiment, the process up to the plating underlayment formation step (Figure 2(A)) can be carried out in the same manner as in the first embodiment.

[0075] Next, in the bending process of the second embodiment, unlike the first embodiment, the substrate is bent using a mold having a bend. Specifically, for example, as shown in Figure 2(B), a mold 5 (upper mold and lower mold) having a desired shape is heated to 200°C, and the expandable substrate 1 is bent by pressing it from above and below with a predetermined molding load (e.g., 1kN to 2000kN) to form a three-dimensional shape of the conductive pattern forming body 4 that will be laminated later. Heating may be performed during the pressing process as needed. Also, when performing the pressing process, a release liner 6 (e.g., made of polyimide) may be used between the mold 5 and the substrate 1.

[0076] After bending, the substrate 1 is removed from the mold 5. Then, the same conductive pattern formation process as in the first embodiment is performed (Figure 2(C)), and then the release liner 6 is peeled off (Figure 2(D)).

[0077] Finally, the substrate 1 on which the plating 3 (conductive pattern) is formed is bonded to the conductive pattern forming body 4 to obtain a conductive patterned substrate (Figure 2(E)). The means for bonding (laminating) the substrate 1 and the conductive pattern forming body 4 is not particularly limited and can be carried out in the same manner as in the first embodiment.

[0078] Furthermore, etching and component mounting steps may be included. The etching and component mounting steps may be performed before bonding to the conductive pattern-forming body 4, or after bonding to the conductive pattern-forming body 4. [Examples]

[0079] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited thereto.

[0080] First, the various materials used in this embodiment are as follows:

[0081] (Epoxy resin) Epoxy resin 1 Acrylonitrile was used as polymerization unit (a), isobornyl acrylate as polymerization unit (b), and polymerization unit (c) represented by the following formula (1) were polymerized in a ratio (polymerization %) of (a):(b):(c) of 10:20:70. Furthermore, glycidyl methacrylate was added as polymerization unit (d) so that the epoxy equivalent relative to the total amount of acrylic resin was the value shown in Table 1. The mixture was then polymerized to obtain epoxy resin 1 (manufactured by Nagase ChemteX Corporation, "PMS-14-67EK40") containing methyl ethyl ketone as a solvent. The solid content ratio was 40% by weight.

[0082] [ka]

[0083] (In the formula, R1 is hydrogen or a methyl group, R2 is hydrogen or an alkyl group, and X is an integer.)

[0084] Epoxy resin 2 Except for changing the amount of polymerization unit (d) of the aforementioned "PMS-14-67EK40", epoxy resin 2 (manufactured by Nagase ChemteX Corporation, "PMS-14-64EK40") was prepared in the same manner, and epoxy resin 2 was obtained. The solid content ratio was 40% by weight.

[0085] Epoxy resin 3 Except for changing the ratio of polymerization units (a) to (d) of the aforementioned "PMS-14-67EK40", epoxy resin 3 (manufactured by Nagase ChemteX Corporation, "PASR-001") was prepared in the same manner. The solid content ratio was 20%.

[0086] • Bisphenol-type epoxy resin (Mitsubishi Chemical Corporation's "jER1006FS")

[0087] (Hardening agent) • Acid anhydride curing agent (Shin Nippon Rika Co., Ltd. "Ricacid TBN-100") • Amine-based curing agent (Porea SL-100A, manufactured by Kumiai Chemical Industry Co., Ltd.) • Carboxylic acid-based curing agent ("TN-1" manufactured by NOF Corporation) • Phenolic curing agent (KAYAHARD GPH-103, manufactured by Nippon Kayaku Co., Ltd.) (Curing accelerator) • Imidazole-based curing accelerator (Shikoku Chemicals "2PZ-CN") (solvent) Methyl ethyl ketone

[0088] <Preparation of semi-cured resin film> Resin varnishes 1 to 7 were prepared by adding a solvent (methyl ethyl ketone) to each component according to the formulation composition (parts by mass) shown in Table 1 below, so that the solid content of the composition was approximately 40% by mass. After degassing by standing, resin varnishes 1 to 7 were applied to PET film (manufactured by Mitsui Chemicals Tohcello Co., Ltd., SP-PET O1) using a bar coater. Then, semi-cured resin films 1 to 7 were obtained by heating in an oven at 80°C for 60 minutes.

[0089] [Table 1]

[0090] <Method for manufacturing hardened resin film> Each of the semi-cured resin films obtained above was further heated at 180°C for 60 minutes to obtain cured resin films 1 to 7. In addition, polyimide film 1 (Ube Industries, Ltd. "UPIREX-S", thickness 25 μm) and polyurethane film 1 (Seedam Co., Ltd. "DUS202-CDR", thickness 100 μm) were prepared as comparative cured films.

[0091] <Evaluation of semi-cured resin films and cured resin films> First, for the semi-cured resin films, the thickness of each film was measured using a micrometer (MDH-25MB, manufactured by Mitutoyo Corporation).

[0092] <Method for measuring tensile modulus and elongation at break> Samples of substrate material (semi-cured resin film and cured resin film) were cut to a size of 90 mm x 5.5 mm and mounted on a universal testing machine (AGS-X, manufactured by Shimadzu Corporation). Tests were conducted at a tensile speed of 500 mm / min, and the tensile modulus was calculated from the stress at elongation rates ranging from 1.0% to 5.0%. The elongation rate at which the sample fractured was also measured.

[0093] In this test, the passing criteria for each evaluation are a tensile modulus of 0.1 MPa or higher and a fracture elongation of 100% or higher.

[0094] <Method for evaluating heat resistance> The following evaluations were conducted regarding the heat resistance of the cured resin film.

[0095] Each cured resin film was cut into 10mm x 30mm pieces and mounted on a dynamic viscoelasticity measuring device (DMS6100, manufactured by Seiko Instruments Inc.). The test was conducted with a strain amplitude of 10 μm, a frequency of 10 Hz (sine wave), and a heating rate of 5°C / min, and the storage modulus at 250°C was measured. The passing criterion for this test is a storage modulus of 0.1 MPa or higher.

[0096] The results above are summarized in Tables 2 and 3 below.

[0097] [Table 2]

[0098] [Table 3]

[0099] In Tables 2 and 3, ">1000" means that the elongation at break was greater than 1000%, and "<0.1" means that the storage modulus at 250°C was less than 0.1 MPa.

[0100] <Circuit board manufacturing> (Examples 1-7 and Comparative Example 3) (Process for forming the plating base) The semi-cured resin films 1-7 obtained above were placed in a desktop printing press (Newlong Precision Industries Co., Ltd., DP-320). Palladium particle-containing ink (Iox Co., Ltd., Metalloid ML-130) was printed onto the surface of the semi-cured resin films using a screen plate of the desired shape. Next, the film was heated in an oven at 80°C for 30 minutes to dry the ink and obtain a semi-cured resin film with a base layer.

[0101] (bending process) Each of the semi-cured resin films with a base layer obtained above was mounted on a press molding machine. The mold temperature was set to 200°C, and a molding load of 100kN was applied to form a hemispherical dome shape. Next, the semi-cured resin film was cured by heating at 180°C for 60 minutes to obtain a cured resin molded body with a base layer.

[0102] (Pre-treatment process) The cured resin molded body with the base layer obtained above is treated with a resin swelling liquid mainly composed of a solvent (manufactured by ROHM & HASH Electronic Materials Co., Ltd., CIRCUPOSIT TM The sample was immersed in a conditioner for 3 minutes. The liquid temperature was 45°C. It was then washed with deionized water.

[0103] (Electroless copper plating process) The cured resin molded body with the undercoat obtained above is then subjected to electroless copper plating (CIRCUPOSIT, manufactured by ROHM & HASH Electronic Materials Co., Ltd.) TM The circuit board was immersed in electroless copper plating for 20 minutes at a temperature of 35°C. It was then rinsed with deionized water and allowed to dry at room temperature. Afterward, it was heated in an oven at 80°C for 60 minutes to perform annealing, resulting in a three-dimensional circuit board with copper-plated circuits.

[0104] (Electrolytic plating process) The 3D circuit board obtained above was then cleaned with an acid cleaning solution (ROHM & Haas Electronic Materials Co., Ltd., ACID CLEANER) TMThe surface was degreased for 10 seconds using (a solution), and then rinsed with deionized water. Next, it was acid-washed with sulfuric acid for 10 seconds, and then rinsed with deionized water. Then, electrolytic copper plating solution (COPPER GLEAM, manufactured by ROHM & Haas Electronic Materials Co., Ltd.) was applied. TM The circuit board was immersed in electrolytic copper plating for 40 minutes. Then it was washed with deionized water and allowed to dry at room temperature. After that, it was heated in an oven at 80°C for 60 minutes to perform annealing, and a three-dimensional circuit board with copper-plated circuits was obtained.

[0105] (Component mounting process) Paste solder (S70G-PX TYPE4, manufactured by Senju Metal Industry Co., Ltd.) was applied to the electrode portion of the 3D circuit board obtained above, and LED elements (APA102-2020, manufactured by Adafruit Industries) were placed on top of it. Next, mounting was performed using an IH reflow system manufactured by Wonder Future Corporation, and the 3D circuit board was peeled off the PET film to obtain a 3D LED module.

[0106] (Lamination process) The 3D LED module obtained above was attached to a rubber ball of the same shape to obtain an LED ball.

[0107] (Example 7) An LED ball was obtained in the same manner as in Example 1, except that the semi-cured resin film 1 in Example 1 was replaced with a cured resin film 1.

[0108] (Comparative Example 1) (Process for forming the plating base) The polyimide film 1 was placed in a desktop printing press (Newlong Precision Industries Co., Ltd., DP-320). Palladium particle-containing ink (Iox Co., Ltd., Metalloid ML-130) was printed onto the surface of the semi-cured resin film using a screen plate of the desired shape. Next, the film was heated in an oven at 80°C for 30 minutes to dry the ink and obtain a polyimide resin film with a base layer.

[0109] (bending process) The polyimide resin film with the underlayer obtained above was mounted on a press molding machine. The mold temperature was set to 280°C and the molding load was 1000kN to form a hemispherical dome shape, thereby obtaining a polyimide resin molded body with an underlayer.

[0110] (Electroless copper plating process) The polyimide resin molded body with the underlayer obtained above is then subjected to electroless copper plating (CIRCUPOSIT, manufactured by ROHM & Haas Electronic Materials Co., Ltd.) TM The circuit board was immersed in electroless copper plating for 20 minutes at a temperature of 35°C. It was then rinsed with deionized water and allowed to dry at room temperature. Afterward, it was heated in an oven at 80°C for 60 minutes to perform annealing, resulting in a three-dimensional circuit board with copper-plated circuits.

[0111] (Electrolytic plating process) The 3D circuit board obtained above was then cleaned with an acid cleaning solution (ROHM & Haas Electronic Materials Co., Ltd., ACID CLEANER) TM The surface was degreased for 10 seconds using (a solution), and then rinsed with deionized water. Next, it was acid-washed with sulfuric acid for 10 seconds, and then rinsed with deionized water. Then, electrolytic copper plating solution (COPPER GLEAM, manufactured by ROHM & Haas Electronic Materials Co., Ltd.) was applied. TM The circuit board was immersed in electrolytic copper plating for 40 minutes. Then it was washed with deionized water and allowed to dry at room temperature. After that, it was heated in an oven at 80°C for 60 minutes to perform annealing, and a three-dimensional circuit board with copper-plated circuits was obtained.

[0112] (Component mounting process) Paste solder (S70G-PX TYPE4, manufactured by Senju Metal Industry Co., Ltd.) was applied to the electrode portion of the 3D circuit board obtained above, and LED elements (APA102-2020, manufactured by Adafruit Industries) were placed on top of it. Next, mounting was performed using an IH reflow system manufactured by Wonder Future Corporation to obtain a 3D LED module.

[0113] (Lamination process) The 3D LED module obtained above was attached to a rubber ball of the same shape to obtain an LED ball.

[0114] (Comparative Example 2) An LED ball was obtained in the same manner as in Example 1, except that the semi-cured resin film 1 of Example 1 was replaced with the polyurethane film 1.

[0115] <Evaluation of circuit boards> (Flexibility) The flexibility of the LED ball obtained above was determined by touch to see if it had not been compromised compared to before it was bonded to the 3D LED module.

[0116] The evaluation criteria were as follows:

[0117] ○: Flexibility is not compromised. ×: Became hard and lost flexibility

[0118] (Appropriate placement of components) The 3D LED module obtained above was connected to an LED controller and power supply, and the LEDs were turned on.

[0119] The evaluation criteria were as follows: ○: Lighted up normally. ×: The light did not illuminate properly, or the circuit board was damaged.

[0120] The results above are summarized in Table 4 below.

[0121] [Table 4]

[0122] <Consideration> The present invention's method for manufacturing a conductive pattern substrate has been confirmed to enable the formation of a circuit board with excellent shape conformability to uneven surfaces and excellent component mounting capabilities.

[0123] On the other hand, in Comparative Example 1, which used polyimide film 1, the flexibility of the substrate was compromised due to insufficient flexibility.

[0124] Furthermore, in Comparative Example 2, which used polyurethane film 1, suitable component mounting could not be achieved. This is thought to be because the film had poor heat resistance, causing the substrate to deteriorate and deform during the component mounting process, preventing proper component mounting.

[0125] Furthermore, in Comparative Example 3, which used a semi-cured resin film 7 with a breaking elongation of less than 100%, good flexibility could not be obtained.

[0126] This application is based on Japanese Patent Application No. 2021-98100, filed on June 11, 2021, the contents of which are included in this application.

[0127] In order to express the present invention, the invention has been adequately and sufficiently described above through embodiments with reference to specific examples and drawings, etc. However, those skilled in the art should recognize that it is easy to modify and / or improve the embodiments described above. Therefore, unless the modifications or improvements implemented by those skilled in the art fall outside the scope of the claims described in the claims, such modifications or improvements shall be interpreted as being included within the scope of the claims. [Industrial applicability]

[0128] The method for manufacturing a conductive patterned substrate according to the present invention has broad industrial applicability in technical fields such as optics, electronics, and medicine, including wearable devices, patch devices, and flexible display devices.

Claims

1. A base preparation step of forming a plating base in a desired pattern on at least a portion of one side of a stretchable substrate having a tensile modulus of 0.1 MPa or more and 500 MPa or less at 20°C, a breaking elongation of 100% or more and 1000% or less, and a storage modulus of 0.1 MPa or more at 250°C, A bending step of bending the aforementioned stretchable substrate, A method for manufacturing a conductive patterned substrate, comprising a conductive pattern forming step of applying plating to the plating base after the bending step to form a conductive pattern on the stretchable substrate.

2. A method for manufacturing a conductive patterned substrate according to claim 1, wherein in the bending step, the stretchable substrate is bent by laminating the stretchable substrate onto the bent portion of a conductive pattern forming body having a bent portion.

3. The method for manufacturing a conductive patterned substrate according to claim 1, wherein in the bending step, the stretchable substrate is bent using a mold having a bent portion, and then the stretchable substrate is removed from the mold.

4. A method for manufacturing a conductive patterned substrate according to any one of claims 1 to 3, wherein the stretchable substrate is formed using a cured or semi-cured product of a resin composition containing a thermosetting resin, and the thermosetting resin contains an epoxy resin having two or more epoxy groups in one molecule.

5. A method for manufacturing a conductive patterned substrate according to any one of claims 1 to 3, further comprising the step of etching the conductive pattern.

6. A base preparation step of forming a plating base on at least a portion of one side of a stretchable substrate having a tensile modulus of 0.1 MPa or more and 500 MPa or less at 20°C, a breaking elongation of 100% or more and 1000% or less, and a storage modulus of 0.1 MPa or more at 250°C, A bending step of bending the aforementioned stretchable substrate, After the bending process, a metal layer forming process is performed, in which plating is applied to the plating base to form a metal layer. A method for manufacturing a conductive patterned substrate, comprising a conductive pattern forming step of etching the metal layer to form a conductive pattern.

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