TW202032681A - Wiring board, method for producing same, and method for producing highly conductive wiring board - Google Patents

Abstract

The present invention provides a wiring board which is suppressed in disconnection of wiring in a bent part, and which exhibits excellent conductivity in the bent part. A wiring board which comprises: a base material that has electrodes on both surfaces; and a wiring line that connects the electrodes on the both surfaces of the base material to each other, while being partially arranged at an end of the base material. This wiring board is configured such that: the wiring line contains an organic material and conductive particles; and the content of the conductive particles in the wiring line is 60-90% by mass.

Description

Wiring board, its manufacturing method, and highly conductive wiring board manufacturing method

The present invention relates to a wiring board, a manufacturing method thereof, and a manufacturing method of a highly conductive wiring board.

In recent years, the development of self-luminous display devices that do not require a backlight by including light-emitting elements such as LEDs in the device is progressing. As the basic structure of such a display device, a light-emitting element with LED elements and metal electrodes on the surface of the substrate is being explored, and a power supply or driving element and metal electrodes for transmitting signals to the light-emitting element are provided on the back of the substrate, and metal wiring is used. The structure of connecting the metal electrodes on the front and back of the substrate.

Regarding the formation method of the metal wiring that connects the metal electrodes on the front and back of the substrate, a method of forming a connection line has been proposed (see, for example, Patent Document 1), which is characterized by having: a first step, in order to miniaturize the edge part of the substrate At least a part of the conductive layer is formed in a range covering both sides and end faces of the substrate; and the second step is to remove a part of the conductive layer and divide it into a plurality of connecting lines that are not conductive to each other. Furthermore, there has also been proposed a wiring substrate (see, for example, Patent Document 2), which is characterized by having: a substrate having a first main surface and a second main surface on the opposite side; and wiring arranged on the aforementioned first main surface The wiring board on the side, wherein three or more conductor lines arranged from the first main surface to the second main surface are arranged side by side in the width direction of the wiring, and the wiring is composed of a part of the three or more conductor lines and a plurality of conductor lines For connection, the aforementioned conductor wire is a side conductor wire arranged on the side surface of the substrate. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] JP 2004-247516 A [Patent Document 2] Japanese Patent Application Publication No. 2018-152565

[The problem to be solved by the invention]

With the narrower frame or higher resolution of electronic devices in recent years, and the increasing rise of μLEDs that replace the above-mentioned LEDs, there is also a great demand for narrower electrode spacing. Furthermore, with the miniaturization-thinness and flexibility of display devices, there is a need for wiring on curved surfaces or bent parts, or conductivity for twists and turns. If the techniques disclosed in Patent Documents 1 and 2 are applied to the formation of wiring on a thin film substrate, the wiring is likely to be broken due to significant twists in the wiring, or the conductivity of the substrate is reduced due to the twists of the substrate, etc. The conductivity of the bent portion also has its problems. .

Therefore, an object of the present invention is to provide a wiring board that can suppress the disconnection of the bent portion and has excellent conductivity of the bent portion. [Means to solve the problem]

The present invention is a wiring board having: a substrate having electrodes on both sides; and wiring, connecting the electrodes on both sides of the substrate, and a part of the electrodes are arranged at the end of the substrate; the wiring contains organic matter and conductive particles, and the wiring is The content of conductive particles is 60 to 90% by mass. [Effects of Invention]

According to the present invention, it is possible to obtain a wiring board having excellent conductivity in the bent portion.

[Form to implement the invention]

The wiring board of the present invention has a base material having electrodes on both sides, and wiring, which connects the electrodes on both sides of the base material, and a part of which is arranged at the end of the base material. With this configuration, the display device can be more miniaturized-narrower. Furthermore, in the present invention, the wiring contains an organic substance and conductive particles, and the condition that the content of the conductive particles in the wiring is 60 to 90% by mass is important. Since the wiring contains organic matter, it can suppress wire breakage at curved or bent parts and improve conductivity. If the content of the conductive particles is less than 60% by mass, the probability of contact between the conductive particles will decrease, and the conductivity will decrease. In addition, in the bent portion of the wiring, the conductive particles become easily dispersed. The content of the conductive particles is preferably 70% by mass or more. On the other hand, if the content of the conductive particles exceeds 90% by mass, it is difficult to form a wiring pattern, and wire breakage is likely to occur in the bent portion. The content of the conductive particles is preferably 80% by mass or less.

Examples of organic substances include epoxy resins, phenoxy resins, acrylic copolymers, and epoxy carboxylate compounds. Two or more of these may be contained. Furthermore, it may also be an organic substance containing a urethane bond. The flexibility of the wiring can be improved by containing an organic substance having a urethane bond. In addition, the organic matter preferably exhibits photosensitivity, so that a fine wiring pattern can be easily formed by photolithography. The photosensitivity is exhibited by containing, for example, a component having a photopolymerization initiator and an unsaturated double bond.

In the present invention, the term "conductive particle" refers to a particle composed of a substance having a resistivity of 10 ^-5 Ω·m or less. Examples of materials constituting the conductive particles include silver, gold, copper, platinum, lead, tin, nickel, aluminum, tungsten, molybdenum, chromium, titanium, indium, antimony, zirconium, palladium, or alloys or oxides of these metals. Carbon particles. More specifically, for example, indium tin oxide, indium oxide-zinc oxide composite oxide, aluminum zinc oxide, indium zinc oxide, fluorine zinc oxide, fluorine indium oxide, antimony tin oxide, or fluorine tin oxide Things.

In the wiring board of the present invention, the wiring preferably contains two or more kinds of conductive particles. By containing two or more kinds of conductive particles, in the heat treatment step described later, the volume shrinkage of the same kind of conductive particles due to sintering can be suppressed. As a result, the volume shrinkage of the wiring as a whole can be suppressed and the tortuosity Be promoted. Here, the term “two or more types” means the case where the particle materials are different, and the case where the material is the same but the contained particle diameters are different is regarded as one type.

Among the two or more types of conductive particles, the ratio of the average particle diameter of the conductive particles with the largest diameter (large diameter particles) to the average particle diameter of the smallest conductive particles (small diameter particles) (large diameter particles/ Small diameter particles) are preferably 5 to 400. If the ratio of the average particle diameter (large-diameter particles/small-diameter particles) is 5 or more, by arranging the small-diameter particles between the large-diameter particles, a conductive path can be easily formed, and the breakage of the meandering part can be suppressed to make conductive Sex is improved. The ratio of the average particle diameter (large diameter particles/small diameter particles) is more preferably 15 or more. On the other hand, if the ratio of the average particle diameter (large diameter particles/small diameter particles) is 400 or less, it is easier to form a wiring pattern of a desired shape. The ratio of the average particle diameter (large diameter particles/small diameter particles) is more preferably 200 or less. Here, the "average particle diameter" refers to the numerical average of the maximum width of the primary particles of 40 conductive particles selected at random. The average particle diameter of the conductive particles in the wiring can be measured by the following method. First, the wiring was dissolved in tetrahydrofuran (THF), the deposited conductive particles were collected, and dried at 70° C. for 10 minutes in a box furnace, and then observed with an electron microscope (SEM) at a magnification of 10000 times and a viewing angle width of 12 μm. With regard to the primary particles of 40 conductive particles selected at random, the maximum width of each is measured, and the average particle diameter of the conductive particles in the wiring is obtained by calculating the average value of these values. When two or more kinds of conductive particles are contained, the average particle diameter is calculated for each conductive particle in the same manner. In addition, since the average particle diameter of the conductive particles constituting the material of the wiring and the average particle diameter of the conductive particles in the wiring do not normally change, the average particle diameter of the conductive particles constituting the material of each wiring is equal to When known, the average particle diameter can be regarded as the average particle diameter of the conductive particles in each wiring. For example, the average particle diameter of large-diameter particles and small-diameter particles is measured in advance by the particle size distribution measurement, and when wiring containing these particles is made, the average particle diameter measured by the particle size distribution meter can be used as the electrical conductivity of the wiring. The average particle diameter of the particles.

Among the two or more types of conductive particles, the mass ratio of the content of the large diameter particles to the content of the small diameter particles (large diameter particles/small diameter particles) is preferably 20 to 1500. If the mass ratio of the content is 20 or more, the probability of contact between large-diameter particles can be further improved, and the conductivity of the wiring can be further improved. The mass ratio of the content (large diameter particles/small diameter particles) is more preferably 30 or more, and still more preferably 50 or more. On the other hand, if the content-to-mass ratio is 1500 or less, there is a high probability that small-diameter particles are arranged between large-diameter particles, the breakage of the bent portion can be more suppressed, and the conductivity can be further improved. The mass ratio of the content (large diameter particles/small diameter particles) is more preferably 1000 or less.

The average particle diameter of the conductive particles is preferably 0.005 to 2.0 μm. The average particle diameter referred to here refers to the average particle diameter of large-diameter particles when two or more kinds of conductive particles are contained. If the average particle diameter of the conductive particles is 0.005 μm or more, the interaction between the conductive particles can be appropriately suppressed, and the dispersion state of the conductive particles can be maintained more stable. The average particle diameter of the conductive particles is more preferably 0.01 μm or more. On the other hand, if the average particle diameter of the conductive particles is 2.0 μm or less, it is easier to form a desired wiring pattern. The average particle diameter of the conductive particles is more preferably 1.5 μm or less.

The thickness of the wiring is preferably 2.0 to 10.0 μm. If the thickness of the wiring is 2.0 μm or more, the disconnection of the bent portion can be more suppressed, and the conductivity can be more improved. The thickness of the wiring is more preferably 4.0 μm or more. On the other hand, when the thickness of the wiring is 10.0 μm or less, the wiring pattern can be formed more easily in the manufacturing step. The thickness of the wiring is more preferably 8.0 μm or less. Here, the thickness of the wiring means the average thickness.

The substrate is a support for forming wiring or the like on the surface thereof, and it is preferable to use, for example, glass, glass-epoxy, ceramics, etc. as a material. Among these materials, from the perspective of versatility and price, glass is better. Furthermore, the thickness of the substrate is preferably 0.3 to 2.0 mm. If the thickness of the base material is 0.3 mm or more, wire breakage can be further suppressed when wiring is formed at the end of the base material. On the other hand, if the thickness of the base material is 2.0 mm or less, the thickness of the entire wiring board is thin, and the display can be thinned.

The end of the base material preferably has a chamfered corner. If the end of the base material is chamfered, even if the wiring is arranged along the shape of the end surface of the base material, since the degree of twisting of the wiring can be smaller than when the chamfered corner is not applied, the disconnection of the wiring can be more suppressed , The increase in resistance value will be more restrained. In addition, the shape and radius of curvature of the chamfered corners can be appropriately selected in consideration of the thickness of the base material and the flexibility of the wiring.

Furthermore, it is preferable that the end of the substrate has a chamfered portion with a chamfer angle of 1° to 70°, and a flat portion of 0.1 mm or more on the side surface. The chamfering angle referred to here, as shown in Fig. 3, refers to the angle 8 formed by the extension of the main surface 5 and the chamfered surface 6. The so-called flat portion 7 indicates a portion substantially orthogonal to the main surface 5. When the chamfering angle is 1° or more, even if the wiring is arranged along the shape of the end surface of the base material, the degree of twisting of the wiring is smaller than when the chamfer is not formed, so the disconnection of the wiring can be more suppressed. On the other hand, if the chamfering angle is 70° or less, it is difficult to produce acute-angled parts on the side surface, and wire breakage can be more suppressed. Furthermore, by having a flat portion of 0.1 mm or more on the side surface, there is no acute-angled portion on the side surface, and wire breakage can be further suppressed. In addition, the angle or width of the chamfer can be appropriately selected after considering the thickness or size of the base material, and the flexibility of the wiring.

In the wiring board of the present invention, as shown in FIG. 1, the electrodes 2 are formed on both sides of the base material 1, and are respectively connected to a part of the wiring 3 arranged at the end of the base material. Various known materials are used for the electrode system, such as indium, tin, zinc, gallium, antimony, molybdenum, titanium, zirconium, magnesium, aluminum, gold, silver, copper, palladium, or tungsten, or oxides of these metals, these Two or more composite materials of materials. Among them, from the viewpoint of high corrosion resistance or high thermal conductivity, Mo/Al/Mo and Ti/Al/Ti are suitably used.

Next, the manufacturing method of the wiring board of the present invention will be described. The manufacturing method of the wiring board of the present invention has in order: forming a photosensitive conductive paste coating film containing organic matter and conductive particles on a thin film; exposing and developing the coating film to obtain a patterned dry film; and drying The film pattern is attached to the substrate with electrodes on both sides, and the steps of heat treatment and film peeling are performed. By this manufacturing method, wiring with a desired pattern can be formed on a large-area substrate. Furthermore, since the dry film with the desired pattern is attached to the substrate in advance, there is no doubt that the substrate will be corroded by the chemicals used in the exposure and development steps, and high-quality displays can be produced. .

The method of manufacturing a wiring board of the present invention includes a step of forming a photosensitive conductive paste coating film containing an organic substance and conductive particles on a thin film. As the film, a polyethylene terephthalate (PET) film coated with a release agent or the like can be used. The term “photosensitive conductive paste” refers to a paste that can form a conductive pattern by photolithography and contains conductive particles. Among them, it is preferable to contain a component having a photopolymerization initiator and an unsaturated double bond. The coating method of the photosensitive conductive paste includes, for example, spraying, roll coating, screen printing, and the use of coating machines (such as knife coaters, die coaters, calender coaters, meniscus coaters). , Rod coater, etc.) coating.

The obtained coating film can also be dried by, for example, heat drying (using an oven, hot plate, infrared rays, etc.) or vacuum drying. The drying time is preferably 1 minute to several hours. When heating and drying, the heating temperature is preferably 50 to 180°C.

The method of manufacturing a wiring board of the present invention includes the steps of exposing and developing the coating film to obtain a patterned dry film. The light source for exposure is preferably i-line (365nm), h-line (405nm), g-line (436nm), etc. of a mercury lamp.

Examples of the development method include alkaline development and organic development.

Developers used for alkaline development include, for example, tetramethylammonium hydroxide, diethanolamine, diethylamine ethanol, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, triethylamine, diethylamine, methyl alcohol, etc. Aqueous solutions of amine, dimethylamine, dimethylaminoethyl acetate, dimethylaminoethanol, dimethylaminoethyl methacrylate, cyclohexylamine, ethylenediamine, hexamethylenediamine, etc. It is also possible to add N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfide, and γ-butyrol to these aqueous solutions. Polar soluble coal such as esters; alcohols such as methanol, ethanol, isopropanol; esters such as ethyl lactate, propylene glycol monomethyl ether acetate; cyclopentanone, cyclohexanone, isobutyl ketone, methyl isobutyl Ketones such as base ketones; surfactants, etc.

The developer for organic development can include, for example, the aforementioned polar soluble coal or a mixed solution of these polar soluble coal and methanol, ethanol, isopropanol, xylene, water, methyl carbitol, and ethyl carbitol. Wait.

The development method includes, for example, a method in which a film with a coating film is left standing or rotated while spraying a developer on the surface of the coating film, a method in which a film with a coating film is immersed in a developer, and a film with a coating film is placed on one side. A method of applying ultrasonic waves while immersing in a developer.

The pattern obtained by development can also be washed with a washing liquid. Examples of the rinsing liquid include water or alcohols such as ethanol and isopropanol added to water; aqueous solutions of esters such as ethyl lactate and propylene glycol monomethyl ether acetate.

The thickness of the above-mentioned film is preferably 10 to 80 μm. If the film thickness is 10 μm or more, the handleability during pattern processing is excellent. On the other hand, when the film thickness is 80 μm or less, it is possible to prevent a gap between the substrate and the dry film when the substrate is attached to the substrate.

The manufacturing method of the wiring board of the present invention includes the steps of attaching a dry film pattern to a substrate having electrodes on both sides, performing heat treatment, and peeling off the film. Through the aforementioned heat treatment, the pattern of the dry film can be transferred to a substrate with electrodes on both sides. Through the aforementioned heat treatment, the pattern can also further exhibit conductivity. Specifically, a base material having electrodes on both sides is bonded together, the pattern is connected to the electrode, and then heat treatment is performed to transfer the pattern to the base material. In the heat treatment step, after heat treatment is applied to the pattern on the side of the substrate, heat treatment is applied to the remaining part. In this way, the occurrence of gaps between the substrate and the dry film can be suppressed. Furthermore, after heat-treating the pattern on one side of the substrate, heat-treating the pattern on the side of the substrate, and then heat-treating the pattern on the other side of the substrate. In this way, the positioning of the electrode and the dry film can be easily performed, and these parts can be reliably bonded. In addition, the patterns on both sides and sides of the substrate may be collectively heat-treated. In this way, the dry film can be transferred in a short time, and productivity is improved.

Examples of the method of heat-treating the above-mentioned pattern include thermocompression bonding using a hot plate, a hot roll laminator, and a mold.

The temperature during the heat treatment is preferably 70°C to 300°C. If the temperature during the heat treatment is 70°C or higher, the pattern can be transferred to the substrate in a short time. The temperature during the heat treatment is more preferably 100°C or higher. On the other hand, if the temperature during the heat treatment is 300°C or less, it is possible to suppress the deformation of the transferred pattern due to heat flow. The temperature during the heat treatment is more preferably 180°C or less.

The method of manufacturing a wiring board of the present invention may further have a step of making the pattern into conductive wiring after the step of peeling the film. The method of imparting conductivity to the transferred pattern includes, for example, heating and drying with an oven, inert gas oven, or hot plate; heating and drying with electromagnetic waves or microwaves such as ultraviolet lamps, infrared heaters, halogen heaters, xenon flash lamps, etc.; Laser processing for IR laser, UV laser, green laser, etc. In the case of imparting conductivity by heating, the heating temperature is preferably 100 to 300°C. When the heating temperature is 100°C, the hardness of the pattern will increase, and cracks or peeling caused by contact with other members can be further suppressed. Moreover, the adhesion to the substrate can be improved. The heating temperature is more preferably 120°C or higher. On the other hand, when the heating temperature is 300°C or lower, the deformation of the transferred pattern due to heat flow is suppressed. The heating temperature is more preferably 180°C or lower. The heating time is preferably 1 minute to several hours.

In the manufacturing method of the wiring board of the present invention, the step of obtaining the dry film further includes a step of forming a resin layer on at least a part of the formed pattern, and a step of bonding the pattern of the dry film to the substrate having electrodes on both sides However, the resin layer may be bonded and arranged on a part other than the electrode. By forming the resin layer, this part can act as a buffer and can prevent the dry film with a pattern from breaking.

In the method of manufacturing a wiring board of the present invention, in the step of bonding a dry film pattern to the substrate with electrodes on both sides, a resin layer may be formed on at least a part of the substrate with electrodes on both sides other than the electrode. The aforementioned dry film pattern is heat-treated. By forming the resin layer, this part can function as a cushioning material, and the disconnection of the dry film with the pattern shape can be suppressed.

Next, the manufacturing method of the highly conductive wiring board of the present invention will be described. Here, in the present invention, the "highly conductive wiring board" refers to a wiring board of the present invention that increases the content of conductive particles in wiring and reduces wiring resistance. The manufacturing method of the highly conductive wiring board of the present invention has the step of irradiating the wiring of the wiring board of the present invention with a laser. The wiring board is manufactured by the aforementioned manufacturing method of the wiring board of the present invention, and it is preferable to irradiate the wiring with a laser. By irradiating the wiring with a laser, components other than conductive particles such as organic matter can be removed, and the content of conductive particles in the wiring can be increased. Therefore, the resistance of the wiring or the contact resistance between the wiring and the electrode can be further reduced, and the conductivity of the bent portion can be further improved. In the presence of a certain amount of organic matter, after wiring is arranged on the end of the substrate in a flexible state, the content of conductive particles in the wiring can be increased by laser irradiation, so it is compared with the content of conductive particles. When wiring exceeding 90% by mass is arranged at the end of the base material, disconnection of the bent portion can be suppressed. In addition, in the method of manufacturing the highly conductive wiring board of the present invention, the content of conductive particles in the wiring irradiated with the laser may be increased compared to before the laser irradiation, and it may exceed 90% by mass.

Examples of lasers include IR lasers, UV lasers, and green lasers. Two or more of these lasers can also be used. Among them, it is better to use an IR laser that can effectively impart heat to resin or metal. [Example]

Although the Examples and Comparative Examples of the present invention are listed and described in detail below, the aspects of the present invention are not limited to these aspects.

>Synthesis example 1: Synthesis of resin (A)> 150 g of dimethylaminomethanol (hereinafter referred to as "DMEA"; manufactured by Tokyo Chemical Industry Co., Ltd.) was placed in a reaction vessel in a nitrogen atmosphere, and the temperature was raised to 80°C using an oil bath. Over a period of 1 hour, 20g of ethyl acrylate (hereinafter referred to as "EA"), 40g of 2-ethylhexyl methacrylate (hereinafter referred to as "2-EHMA"), 20g of styrene (hereinafter referred to as It is called "St"), 15 g of acrylic acid (hereinafter referred to as "AA"), 0.8 g of 2,2'-azobisisobutyronitrile, and a mixture of 10 g of DMEA. After the dropping, the polymerization reaction was carried out at 80° C. in a nitrogen atmosphere for 6 hours. Then, 1 g of hydroquinone monomethyl ether was added to stop the polymerization reaction. Next, a mixture of 5 g of glycidyl methacrylate (hereinafter referred to as "GMA"), 1 g of benzyltriethylammonium chloride, and 10 g of DMEA was dropped over 0.5 hours. After the dropping, the addition reaction was carried out at 80°C for 2 hours in a nitrogen atmosphere. The resulting reaction solution was purified with methanol to remove unreacted impurities, and then vacuum dried for 24 hours to obtain the copolymerization ratio (quality basis): EA/2-EHMA/St/GMA/AA=20/40 /20/5/15 resin (A). The acid value of the obtained resin (A) was 103 mgKOH/g.

> Preparation example 1: Preparation of photosensitive conductive paste 1> Put 10.0 g of resin (A) as a resin, 0.50 g of "IRGACURE" (registered trademark) OXE-01 (manufactured by Ciba Japan Co., Ltd.) as a photopolymerization initiator, and 5.0 g of resin in a 100 mL clean bottle DMEA was used as a solvent, and 2.0 g of "LIGHTACRYLATE" (registered trademark) BP-4EA (manufactured by Kyoeisha Chemical Co., Ltd.) as a compound with unsaturated double bonds, and a rotation-revolution vacuum mixer "Awatori Chain Taro ARE-310" (Shinky Co., Ltd.) was mixed to obtain 17.5 g of a resin solution (solid content 71.4% by mass).

The obtained resin solution 17.50 g, silver particles with an average particle diameter of 1.0 μm 44.02 g, and 0.28 g of carbon black with an average particle diameter of 0.05 μm were mixed, and a 3-roll mill "EXAKT M-50" (manufactured by EXAKT) was used. ) Kneading was performed to obtain 61.8 g of photosensitive conductive paste 1. In addition, the average particle diameter of the silver particles and carbon black was measured using an electron microscope (SEM) with a magnification of 10000 times and a viewing angle range of 12 μm. The largest of each particle was measured with 40 silver particles and carbon black primary particles selected at random. Width and calculate the numerical average of these particles.

> Preparation example 2: Preparation of photosensitive conductive paste 2> Except that 23.03 g of silver particles with an average particle diameter of 1.0 μm and 0.179 g of carbon black with an average particle diameter of 0.05 μm were used, the rest was the same as in Preparation Example 1, and a photosensitive conductive paste 2 was obtained.

>Preparation example 3: Preparation of photosensitive conductive paste 3> Except that 70.39 g of silver particles with an average particle diameter of 1.0 μm and 0.417 g of carbon black with an average particle diameter of 0.05 μm were used, the rest was the same as in Preparation Example 1, and photosensitive conductive paste 3 was obtained.

>Preparation example 4: Preparation of photosensitive conductive paste 4> Except that carbon black with an average particle diameter of 0.01 μm was used instead of carbon black with an average particle diameter of 0.05 μm, the rest was the same as Preparation Example 1, and photosensitive conductive paste 4 was obtained.

> Preparation example 5: Preparation of photosensitive conductive paste 5> Except that silver particles with an average particle diameter of 1.5 μm were used instead of silver particles with an average particle diameter of 1.0 μm, the rest was the same as Preparation Example 1, and photosensitive conductive paste 5 was obtained.

>Preparation example 6: Preparation of photosensitive conductive paste 6> Except that silver particles with an average particle diameter of 1.5 μm are used instead of silver particles with an average particle diameter of 1.0 μm, and carbon black with an average particle diameter of 0.01 μm is used instead of carbon black with an average particle diameter of 0.05 μm, the rest is the same as Preparation Example 1. And a photosensitive conductive paste 6 was obtained.

>Preparation example 7: Preparation of photosensitive conductive paste 7> Except that 43.45 g of silver particles with an average particle diameter of 1.0 μm and 0.850 g of carbon black with an average particle diameter of 0.05 μm were used, the rest was the same as in Preparation Example 1, and a photosensitive conductive paste 7 was obtained.

>Preparation example 8: Preparation of photosensitive conductive paste 8> Except that 44.24 g of silver particles with an average particle diameter of 1.0 μm and 0.057 g of carbon black with an average particle diameter of 0.05 μm were used, the rest was the same as in Preparation Example 1, and photosensitive conductive paste 8 was obtained.

>Preparation example 9: Preparation of photosensitive conductive paste 9> Except that 44.26 g of silver particles with an average particle diameter of 1.0 μm and 0.040 g of carbon black with an average particle diameter of 0.05 μm were used, the rest was the same as in Preparation Example 1, and a photosensitive conductive paste 9 was obtained.

>Preparation example 10: Preparation of photosensitive conductive paste 10> Except that 44.02 g of silver particles with an average particle diameter of 1.0 μm and 0.280 g of antimony tin oxide with an average particle diameter of 0.05 μm were used, the rest was the same as Preparation Example 1, and a photosensitive conductive paste 10 was obtained. In addition, the average particle diameter of antimony tin oxide was observed using an electron microscope (SEM) with a magnification of 10000 times and a viewing angle width of 12 μm. 40 randomly selected silver particles and primary particles of antimony tin oxide were measured. The maximum width of the particles, and calculate the average value of these particles.

>Preparation example 11: Preparation of photosensitive conductive paste 11> Except that 12.37 g of silver particles with an average particle diameter of 1.0 μm and 0.125 g of carbon black with an average particle diameter of 0.05 μm were used, the rest was the same as in Preparation Example 1, and a photosensitive conductive paste 11 was obtained.

>Preparation example 12: Preparation of photosensitive conductive paste 12> Except that 236.16 g of silver particles with an average particle diameter of 1.0 μm and 1.250 g of carbon black with an average particle diameter of 0.05 μm were used, the rest was the same as in Preparation Example 1, and a photosensitive conductive paste 12 was obtained.

The evaluation method of each example and comparative example is as follows.

>Evaluation of resistivity before transfer> As an index of conductivity, the tester was used to connect the two ends of the sample for resistivity measurement (initial resistance before transfer) obtained by each embodiment and comparative example, and the resistance value was measured, and the resistance value was measured from the following formula ( 1) Calculate the resistivity. In addition, this value is used as an initial value when obtaining the resistance change rate after transfer. Resistivity = resistance value×film thickness×line width/line length ･･･ (1).

>Observation and evaluation of transfer part> As an index of the wire breakage suppression effect of the bent portion, the transfer sample obtained in each of the Examples and Comparative Examples was observed with an optical microscope at a magnification of 1000 times and a viewing angle width of 350 μm. Among the wires after the transfer, those with no broken wires were judged as unbroken, and those with broken wires, poor transfer, or cracks in the wires after the transfer were judged as broken wires.

>Evaluation of resistivity after transfer> As an indicator of the conductivity of the zigzag part, a tester was used to connect both ends of the wiring of the transfer sample obtained in each of the examples and comparative examples, and the resistance value was measured, and the resistivity was calculated by formula (1). In addition, the resistance change rate is calculated from the following formula (2), and the calculated resistance change rate is 1.20 or less as A, the resistance change rate is greater than 1.20 but less than 2.00 is judged as B, and the resistance change rate is greater than 2.00 The resistance value after transfer and the resistance value after transfer were judged to be C. Resistance change rate = resistivity after transfer / initial resistivity before transfer ･･･ (2).

>Tortuous assessment> Regarding the tortuosity evaluation samples obtained in each of the Examples and Comparative Examples, the 50 μm width portion of the tortuosity evaluation sample was wound around the thickness of 0.3mm, 0.4mm, 0.5mm, 0.7mm, 1.0mm, 1.2mm, 1.5mm, 2.0mm spacers (made of SUS), and place a glass plate on the spacers to fix them, and evaluate the tortuosity. The thickness of the spacer here is regarded as the zigzag diameter (ϕ). Then, the resistance value after fixing and standing for 10 minutes is measured, the resistivity is calculated by formula (1), and the resistance change rate is calculated from the following formula (3). Those with a calculated resistance change rate of 1.10 or less are judged to be able to bend in the evaluated tortuous path, and those with a resistance change rate greater than 1.10 and those with a zigzag sample showing insulation are judged to be unable to bend in the evaluated tortuous path. Perform this measurement to find the smallest tortuous diameter that can be bent. Resistance change rate = resistivity after bending / resistivity before bending ･･･ (3).

(Example 1)> Preparation of resistivity measurement (initial resistance before transfer) and preparation of sample for bending property evaluation> The photosensitive conductive paste 1 obtained in Preparation Example 1 was coated on a PET film with a thickness of 50 μm. The film thickness after drying can reach 6.0 μm, and the obtained coating film is dried in a drying oven at 100° C. for 10 minutes. Through the light-transmitting mask shown in Figure 2, using an exposure machine with an ultra-high pressure mercury lamp with an exposure amount of 350mJ/cm ² , using 0.1% by mass sodium carbonate aqueous solution as the developer, with 0.1MPa Pressure spray development for 30 seconds to obtain a pattern. Then, the obtained pattern was cured in a drying oven at 140°C for 30 minutes to obtain samples for resistivity measurement and for evaluation of bending properties. The resulting pattern has a line width of 50 μm and a line length of 90 mm.

>Production of transfer sample> On a release PET film coated with a release agent on a PET film with a thickness of 16 μm, a pattern was prepared in the same way as> Preparation of resistivity measurement and tortuosity evaluation sample to obtain a transfer sample . A part of the wiring is placed on the glass end with a chamfered corner. The transfer sample is attached to both sides, and the side of the glass is pressed on a hot plate at 130°C for 30 seconds, and then a hot roll laminate is used The remaining part was transferred under conditions of 130°C and 1.0 m/min to obtain a transfer sample.

(Examples 2-15, 19, Comparative Examples 1, 2) Except that the type of photosensitive conductive paste, the thickness of the wiring, and the chamfered portion of the glass end are changed as shown in Tables 1 and 2, the rest is the same as in Example 1, and the resistivity measurement sample and Transfer the sample.

(Example 16) Except that in the>Production of Transfer Sample> in (Example 1), the transfer method is different in the order of front, side, and back. The rest of the system is the same as that of Example 1, and the sample is made and evaluated. . Specifically, the transfer sample was attached to both sides so that a part of the wiring was arranged at the end of the glass with chamfered corners, and the pattern on one side of the substrate was transferred on a hot plate at 130°C for 30 seconds After that, the pattern on the side of the substrate was transferred for 30 seconds, and then the pattern on the other side of the substrate was transferred to prepare a transfer sample.

(Example 17) Except in the>Production of transfer sample> in (Example 1), the end of the glass was immersed in the resin solution and pulled up, and dried in a drying oven at 100°C for 10 minutes, and the transfer sample was different Otherwise, the sample preparation and evaluation were performed in the same manner as in Example 1.

(Example 18) Except in the>Preparation of transfer sample> in (Example 1), a part of the transfer sample wiring was coated with a resin solution and dried in a drying oven at 100°C for 10 minutes. The transfer sample was different Otherwise, the sample preparation and evaluation were performed in the same manner as in Example 1.

The compositions of Examples 1 to 19 and Comparative Examples 1 and 2 are disclosed in Tables 1 and 2, and the evaluation results are shown in Table 3.

[Table 1] The ratio of conductive particles to the total solid content (mass%) Types of photosensitive conductive paste Large diameter particles Trail particle Relative to total solid content (mass%) species Average particle diameter (μm) Relative to the mass ratio of small diameter particles Relative to the particle size ratio of small diameter particles Relative to total solid content (mass%) species Average particle diameter (μm) Example 1 78.0 Modulation example 1 77.5 Ag 1.0 155 20 0.5 Carbon black 0.05 Example 2 65.0 Modulation example 2 64.5 Ag 1.0 129 20 0.5 Carbon black 0.05 Example 3 85.0 Modulation example 3 84.5 Ag 1.0 169 20 0.5 Carbon black 0.05 Example 4 78.0 Modulation example 4 77.5 Ag 1.0 155 100 0.5 Carbon black 0.01 Example 5 78.0 Modification example 5 77.5 Ag 1.5 155 30 0.5 Carbon black 0.05 Example 6 78.0 Modulation example 6 77.5 Ag 1.5 155 150 0.5 Carbon black 0.01 Example 7 78.0 Modulation example 7 76.5 Ag 1.0 51 20 1.5 Carbon black 0.05 Example 8 78.0 Modulation example 8 77.9 Ag 1.0 779 20 0.1 Carbon black 0.05 Example 9 78.0 Modification example 9 77.93 Ag 1.0 1113 20 0.07 Carbon black 0.05 Example 10 78.0 Modification example 10 77.5 Ag 1.0 155 20 0.5 Antimony Tin Oxide 0.05 Example 11 78.0 Modulation example 1 77.5 Ag 1.0 155 20 0.5 Carbon black 0.05 Example 12 78.0 Modulation example 1 77.5 Ag 1.0 155 20 0.5 Carbon black 0.05 Example 13 78.0 Modulation example 1 77.5 Ag 1.0 155 20 0.5 Carbon black 0.05 Example 14 78.0 Modulation example 1 77.5 Ag 1.0 155 20 0.5 Carbon black 0.05 Example 15 78.0 Modulation example 1 77.5 Ag 1.0 155 20 0.5 Carbon black 0.05 Example 16 78.0 Modulation example 1 77.5 Ag 1.0 155 20 0.5 Carbon black 0.05 Example 17 78.0 Modulation example 1 77.5 Ag 1.0 155 20 0.5 Carbon black 0.05 Example 18 78.0 Modulation example 1 77.5 Ag 1.0 155 20 0.5 Carbon black 0.05 Example 19 78.0 Modulation example 1 77.5 Ag 1.0 155 20 0.5 Carbon black 0.05 Comparative example 1 50.0 Modulation example 11 49.5 Ag 1.0 99 20 0.5 Carbon black 0.05 Comparative example 2 95.0 Modification example 12 94.5 Ag 1.5 189 30 0.5 Carbon black 0.05

[Table 2] Wiring thickness (μm) Transfer target substrate Resin Transfer method species Thickness(mm) Chamfer Example 1 6.0 glass 1.0 R side no Side → other general Example 2 6.0 glass 1.0 R side no Side → other general Example 3 6.0 glass 1.0 R side no Side → other general Example 4 6.0 glass 1.0 R side no Side → other general Example 5 6.0 glass 1.0 R side no Side → other general Example 6 6.0 glass 1.0 R side no Side → other general Example 7 6.0 glass 1.0 R side no Side → other general Example 8 6.0 glass 1.0 R side no Side → other general Example 9 6.0 glass 1.0 R side no Side → other general Example 10 6.0 glass 1.0 R side no Side → other general Example 11 9.0 glass 1.0 R side no Side → other general Example 12 3.0 glass 1.0 R side no Side → other general Example 13 6.0 glass 1.0 Angle surface 10°, side flat part 0.6mm no Side → other general Example 14 6.0 glass 1.0 Angle face 30°, side flat part 0.3mm no Side → other general Example 15 6.0 glass 1.0 Angle surface 50°, side flat part 0.2mm no Side → other general Example 16 6.0 glass 1.0 R side no Front → side → back Example 17 6.0 glass 1.0 no Resin layer on base material Side → other general Example 18 6.0 glass 1.0 no Dry film with resin layer Side → other general Example 19 7.0 glass 1.0 no no Side → other general Comparative example 1 6.0 glass 1.0 R side no Side → other general Comparative example 2 6.0 glass 1.0 R side no Side → other general

[table 3] Transferability evaluation Tortuous assessment Initial resistivity before transfer (Ω・cm) Observation and evaluation of transfer department Resistivity after transfer (Ω・cm) Resistance change rate determination Minimum bending diameter (ϕ)(mm) Resistance change rate at minimum bending diameter Example 1 7.0×10 ^-5 No disconnection 7.9×10 ^-5 1.13 A 0.3 1.03 Example 2 7.6×10 ^-5 No disconnection 8.4×10 ^-5 1.11 A 0.3 1.01 Example 3 5.8×10 ^-5 No disconnection 7.0×10 ^-5 1.21 B 0.5 1.02 Example 4 6.8×10 ^-5 No disconnection 7.8×10 ^-5 1.15 A 0.3 1.02 Example 5 6.5×10 ^-5 No disconnection 7.3×10 ^-5 1.12 A 0.3 1.02 Example 6 6.3×10 ^-5 No disconnection 7.3×10 ^-5 1.16 A 0.3 1.01 Example 7 8.1×10 ^-5 No disconnection 9.0×10 ^-5 1.11 A 0.4 1.05 Example 8 6.3×10 ^-5 No disconnection 7.0×10 ^-5 1.11 A 0.3 1.02 Example 9 6.1×10 ^-5 No disconnection 7.1×10 ^-5 1.16 A 0.3 1.01 Example 10 4.8×10 ^-5 No disconnection 5.4×10 ^-5 1.13 A 0.3 1.03 Example 11 7.0×10 ^-5 No disconnection 7.9×10 ^-5 1.13 A - - Example 12 7.0×10 ^-5 No disconnection 9.4×10 ^-5 1.34 B - - Example 13 7.0×10 ^-5 No disconnection 8.0×10 ^-5 1.14 A - - Example 14 7.0×10 ^-5 No disconnection 8.0×10 ^-5 1.14 A - - Example 15 7.0×10 ^-5 No disconnection 8.1×10 ^-5 1.16 A - - Example 16 7.0×10 ^-5 No disconnection 7.9×10 ^-5 1.13 A - - Example 17 7.0×10 ^-5 No disconnection 8.9×10 ^-5 1.27 B - - Example 18 7.0×10 ^-5 No disconnection 9.0×10 ^-5 1.29 B - - Example 19 7.0×10 ^-5 No disconnection 1.3×10 ^-4 1.86 B - - Comparative example 1 insulation No disconnection insulation - C - - Comparative example 2 4.1×10 ^-5 Broken wire at the end insulation - C 2.0 1.08

(Example 20) For the wiring of the transfer sample obtained in> Preparation of Transfer Sample> of (Example 1), the laser was irradiated using "Semiconductor Laser TRM60TC-LN for Firing" (manufactured by Tamari) , And obtain a high-conductivity wiring substrate sample. The conditions of the laser used were that the center wavelength was 970nm, the output was 140W, and the wiring was irradiated for 7 seconds. Connect both ends of the wiring of the obtained sample with a tester, measure the resistance value, and calculate the resistivity by formula (1), and the result is 9.8×10 ^-6 (Ω･cm).

As can be seen from Table 3, in the transfer evaluation, the resistance change rate of the samples of Examples 1 to 19 before and after the transfer was as small as 1.9 or less. In addition, no disconnection was observed in the observation and evaluation of the transfer portion. Furthermore, in the tortuosity evaluation, the smallest tortuous diameter that can be bent is also as small as 0.5mm or less. On the other hand, in the samples of Comparative Examples 1 and 2, wire breakage was observed before or after the transfer, and the resistance change rate could not be calculated. In the tortuosity evaluation of Comparative Example 2, the smallest tortuous diameter was Up to 2.0mm. In addition, as a result of irradiating the wiring of the sample after the transfer with a laser, a sample with a smaller resistivity can be obtained from Example 20.

1: substrate 2: electrode 3: Wiring 4: Light transmission form 5: Main side 6: Beveled face 7: The flat part of the side 8: Chamfer angle

Fig. 1 is a schematic diagram of a cross-sectional structure of a wiring board of the present invention. 2 is a schematic diagram of the light transmission form of the photomask used in the evaluation of the resistivity, the evaluation of the tortuosity, and the evaluation of the transferability of the embodiment. Figure 3 is a schematic view of the chamfer angle.

1: substrate

2: electrode

3: Wiring

Claims (17)

A wiring board having: a base material having electrodes on both sides; and Wiring connects the electrodes on both sides of the substrate, and one part is arranged at the end of the substrate, The aforementioned wiring contains an organic substance and conductive particles, and the content of the conductive particles in the wiring is 60 to 90% by mass. The wiring board according to claim 1, wherein the wiring contains two or more kinds of conductive particles. The wiring board according to claim 2, wherein among the two or more kinds of conductive particles, the average particle diameter of the conductive particle with the largest particle diameter (large diameter particle) is relative to that of the conductive particle with the smallest particle diameter (small diameter particle). The ratio of the average particle diameter (large diameter particle/small diameter particle) of) is 5 to 400. The wiring board according to claim 3, wherein the mass ratio of the content of large diameter particles to the content of small diameter particles (large diameter particles/small diameter particles) among the two or more types of conductive particles is 20 to 1500. The wiring board according to any one of claims 1 to 4, wherein the average particle diameter of the conductive particles is 0.005 to 2.0 μm. The wiring board according to any one of claims 1 to 5, wherein the thickness of the aforementioned wiring is 2.0 to 10.0 μm. The wiring board according to any one of claims 1 to 6, wherein the base material contains at least one selected from the group consisting of glass, epoxy glass, and ceramics, and the base material has a thickness of 0.3 to 2.0 mm. The wiring board according to any one of claims 1 to 7, wherein the base material has a chamfered corner portion at the end. The wiring board according to any one of claims 1 to 8, wherein the end of the base has a chamfered portion with a chamfer angle of 1° to 70°, and a flat portion of 0.1 mm or more on the side surface. A method for manufacturing a wiring board is the method for manufacturing a wiring board according to any one of claims 1 to 9, at least sequentially having: The step of forming a photosensitive conductive paste coating film containing organic matter and conductive particles on the thin film; The steps of exposing and developing the coating film to obtain a patterned dry film; and A step of bonding the dry film pattern to the aforementioned substrate with electrodes on both sides, and performing heat treatment at 70°C to 300°C, and peeling the film. The method of manufacturing a wiring board according to claim 10, wherein the step of the heat treatment includes a step of heat-treating the remaining part after heat-treating the pattern on the side of the base material. The method of manufacturing a wiring board according to claim 10, wherein the step of heat treatment includes heat treatment of the pattern on one side of the base material, heat treatment of the pattern on the side of the base material, and then heat treatment on the other side of the base material The pattern is subjected to a step of heat treatment. The method for manufacturing a wiring board according to claim 10, wherein the step of heat treatment includes a step of collectively performing heat treatment on the patterns on both sides and side surfaces of the base material. The method for manufacturing a wiring board according to any one of claims 10 to 13, wherein the step of obtaining the aforementioned dry film further has a step of forming a resin layer on at least a part of the formed pattern, and having electrodes on both sides In the step of bonding the dry film pattern to the base material, the resin layer is arranged and bonded to the part other than the electrode. The method of manufacturing a wiring board according to any one of claims 10 to 13, wherein in the step of attaching the dry film pattern to the substrate having electrodes on both sides, the substrate having electrodes on both sides is not part of the electrodes After at least part of the resin layer is formed, the dry film pattern is heat-treated. A method of manufacturing a highly conductive wiring board, which has a step of irradiating a laser on the wiring of the wiring board in any one of claims 1 to 9. A method for manufacturing a highly conductive wiring substrate, which has: Each step of the manufacturing method of the wiring board of any one of claims 10 to 15; and The step of irradiating a laser on the wiring of the wiring board obtained by the manufacturing method.

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