JP2012079683A - Conductive paste and circuit board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductive paste which achieves both high dispersion characteristics and electrical conductivity.SOLUTION: A conductive paste 1 contains 0.01-30 parts by weight of a carbon nanohorn aggregate 3 relative to 100 parts by weight of conductive particles 4 and contains a curable resin more than carbon nanohorns 2. The conductive particles are composed of silver, copper, gold, tin, indium, nickel, palladium, a mixture of a plurality of particles composed of metals selected from a group consisting of them, or an alloy made of them. The curable resin is a thermosetting resin or a photocurable resin.

Description

  The present invention relates to a conductive paste containing metal particles and a circuit board using the same.

  Generally, as a method of forming a circuit pattern on a substrate, a metal wiring material is formed on the entire surface of the substrate and a subtractive method of removing portions other than the wiring portion, or a resist is formed on a portion where no wiring is formed, and there is no resist. The additive method etc. which form a pattern by plating a part are performed.

  These circuit pattern forming methods have problems in terms of environmental protection because of the large amount of discarded wiring materials, and in terms of cost because they require expensive substrates. In recent years, as an alternative technique, a method of forming a circuit pattern by printing or the like using a conductive paste on a substrate has been developed.

  The conductive paste is used for conductive connection of electronic components having low heat resistance and forming a circuit pattern on a substrate material having low heat resistance. Therefore, the conductive paste is required to be cured at a relatively low temperature range, for example, a temperature of 180 ° C. or lower.

  Furthermore, since the conductive paste is used for conductive connection of electronic components, circuit pattern formation, and the like, it needs to have low resistance. However, as compared with a general conductive paste, a low temperature curing type conductive paste tends to have a small volumetric shrinkage when cured. For this reason, it is difficult for the low temperature curing type conductive paste to secure a stable contact area between the metal particles in the cured conductive paste, and thus it was not possible to obtain a practically low resistance. .

  In recent years, it has been proposed to mix carbon nanotubes with the conductive paste.

  In Patent Document 1, 100 parts by weight of a curable resin, 1 to 100 parts by weight of a curing agent component, 40 to 90 parts by weight of metal particles, 0.05 to 20 parts by weight of carbon nanotubes, and 0.1 to 0.1 parts of a viscosity modifier. The description regarding the electrically conductive paste comprised by -100 weight part is made.

Further, Patent Document 2 includes carbon nanotubes contained in a conductive filler in addition to silver powder.
The conductive resin paste is described. According to the above configuration, it is described that the migration resistance of the conductive resin paste composition can be remarkably improved without causing a problem in the resistance value and the adhesive strength.

  Patent Document 3 describes a conductive paste containing carbon nanotubes selected from the group consisting of single walls, multiple walls, and mixtures thereof, and a conductive paste used by coating the carbon nanotubes with metal particles.

JP2008-293821 JP 2006-120665 A JP 2009-117340 A

  However, the conductive paste containing carbon nanotubes described in Patent Documents 1 to 3 has a problem in terms of dispersion characteristics. That is, since the carbon nanotube has a shape with a high aspect ratio, the carbon nanotubes are bundled or entangled with each other. As a result, the dispersion characteristics with respect to the solvent and other materials are poor, and it is impossible to uniformly disperse in the conductive paste, so that there is a problem that high conductivity cannot be ensured.

  Then, an object of this invention is to provide the electrically conductive paste which solves the said subject.

  The conductive paste according to the present invention includes 0.01 to 30 parts by weight of carbon nanohorn aggregates with respect to 100 parts by weight of conductive particles, and more curable resin than the carbon nanohorns. .

  The conductive paste according to the present invention can achieve high conductivity.

It is a schematic diagram of the conductive paste 1 in the first embodiment. It is the figure which represented the carbon nanohorn aggregate | assembly 3 typically. FIG. 6 is a process diagram when the conductive paste 1 is supplied to the surface of the substrate 6. It is a schematic diagram of the conductive paste 1 before and after curing.

  [First Embodiment] A preferred embodiment for carrying out the present invention will be described below with reference to the drawings. However, the preferred embodiments described below are technically preferable for carrying out the present invention, but the scope of the invention is not limited to the following.

  [Description of Configuration] FIG. 1 is a diagram schematically showing a conductive paste 1 according to this embodiment. The conductive paste 1 in this embodiment includes a carbon nanohorn aggregate 3, which is an aggregate of carbon nanohorns 2, conductive particles 4, and a curable resin 5.

  The carbon nanohorn 2 has a conical shape in which the tip of the carbon nanotube is pointed in a horn shape with a tip angle of about 20 °. In general, as shown in FIG. 2, the carbon nanohorns 2 are gathered radially with a conical tip portion on the outside, forming a spherical carbon nanohorn aggregate 3 having a diameter of about 100 nm. The carbon nanohorn aggregate 3 is expected to be used as an adsorbent because of its unique structure and the characteristic of selectively adsorbing various gases.

  The carbon nanohorn aggregate 3 is preferably a spherical aggregate shown in FIG. 2, but may be an aggregate having any shape as long as the diameter of the aggregate is 30 to 300 nm. Further, the carbon nanohorn 2 or the carbon nanohorn aggregate 3 includes a dahlia type having a long horn structure, a bad type having a short horn structure, and a petal structure having a plate-like horn portion.

  The carbon nanohorn aggregate 3 in the present embodiment has a three-dimensional dimension in which all dimensions are 30 to 500 nm (or 500 nm or less) and a D / G ratio is 0.5 to 1.5. The D / G ratio is a ratio between the G band corresponding to the vibration mode in the graphite (six-membered ring carbon atom) plane and the D band resulting from defects in the six-membered ring.

  In other words, as the general carbon nanotube has better crystallinity, the D / G ratio becomes smaller. On the other hand, a tube having poor crystallinity even with a carbon nanotube has a large D / G ratio. Since the carbon nanohorn aggregate 3 in the present embodiment has a conical shape with a sharp tip, the carbon nanohorn aggregate 3 has a D / G ratio of 0.5 to 5 compared to a carbon nanotube having a general D / G ratio of 0.2 or less. A large value of 1.5.

  The conductive particles 4 are made of silver, copper, gold, tin, indium, nickel, palladium, and a mixture or alloy of one or more kinds of particles selected from the group consisting of these compounds. The For example, when one kind of metal is used, Ag, Cu, Au, or the like can be used. When a combination of two or more metals is used, an alloy composition such as Sn—Ag, Sn—Cu, Sn—Ag—Cu can be used.

  The shape of the conductive particles 4 is not particularly limited, and various shapes such as spherical, scale-like, plate-like, dendritic, massive, granular, rod-like, foil-like, and needle-like particles can be used. . As the conductive particle 4, any metal particle can be suitably used as long as it is selected from the group described above.

  As the curable resin 5, a resin that can be cured by applying heat, light, or the like in the presence of a suitable combination of curing agents can be used. As such a resin, for example, a resin selected from the group of epoxy resins, acrylic resins, phenol resins, polyimide resins, silicone resins, polyurethane resins, and unsaturated polyester resins can be used. Therefore, as the curing agent component, a substance known to those skilled in the art in this technical field can be used as a substance that initiates curing of the above-described resin by applying heat, light, or the like.

  The thermosetting curable resin 5 is a material that is preferably used in this embodiment from the viewpoint that the start of curing can be controlled by raising the temperature from the low temperature side and the curing reaction can be easily managed. An epoxy resin as a so-called thermosetting resin, for example, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, or a modified one thereof can be used.

  As a photocurable curable resin 5, a person skilled in the art can start a curing reaction with light of various wavelengths such as ultraviolet rays, visible rays, and infrared rays in combination with a curing agent component. Those known in the art can be used.

  As the curing agent, a combination of suitable curing agent components corresponding to the curable resin 5 is generally known, and such a combination can also be used in this embodiment. As the curing agent component, when an epoxy resin is used as the curable resin 5, in order to cure the epoxy resin in a relatively low temperature range of 80 to 190 ° C., from thiol, amine, and acid anhydride Selected materials can be used.

  [Explanation of Action] Next, actions and effects in this embodiment will be described.

  The carbon nanohorn 2 having one graphene sheet is considered to have high conductivity. Further, since the carbon nanohorn aggregate 3 is difficult to be decomposed into individual carbon nanohorns 2, it is presumed that the carbon nanohorns 2 are partially chemically bonded to each other. For this reason, it is considered that one spherical and massive carbon nanohorn aggregate 3 has high conductivity.

  However, when there are a plurality of carbon nanohorn aggregates 3, the carbon nanohorn aggregates 3 have high contact resistance. Therefore, the carbon nanohorn powder in a state where the carbon nanohorn aggregates 3 are gathered has a slightly lower conductivity than the carbon nanotube. For this reason, when the conductive paste 1 contains the carbon nanohorn aggregate 3 as a mixture, the effect of improving the conductivity of the conductive paste 1 is considered to be low at first glance.

  However, the carbon nanohorn aggregate 3 has a characteristic that the dispersion characteristics in a solvent and other materials are much better than the carbon nanotube due to its shape. For this reason, the carbon nanohorn aggregate 3 can be uniformly dispersed in the conductive paste 1 to allow the carbon nanohorn aggregate 3 to enter between the conductive particles 4.

  Therefore, the conductive paste 1 in the present embodiment has a structure in which the carbon nanohorn aggregates 3 are uniformly dispersed in addition to the conductive particles 4 and the curable resin 5.

  The method of uniformly dispersing the carbon nanohorn aggregate 3 in the conductive paste 1 can be produced by mixing and dispersing and kneading simultaneously with other conductive paste materials. Further, the conductive paste can be prepared by adding the carbon nanohorn aggregate to the conductive paste having already been kneaded with other materials and kneading. Both of the above production methods can produce a conductive paste in which carbon nanohorn aggregates are uniformly dispersed.

  In the conductive paste 1, when the carbon nanohorn aggregates 3 are uniformly dispersed, the carbon nanohorn aggregates 3 uniformly enter the gaps between the conductive particles 4 and the curable resin 5. When the curable resin 5 is cured in the conductive paste 1, the entire volume of the curable resin 5 contracts, and the interval between the conductive particles 4 becomes narrow. In a portion where the interval between the conductive particles 4 is narrow, the carbon nanohorn aggregate 3 can enter between the conductive particles 4 as a single unit, and can serve as a good conductive path for the conductive particles 4. Further, in the portion where the interval between the conductive particles 4 is slightly wide, some of the carbon nanohorn aggregates 3 are present in an aggregated state. However, even if there is contact resistance between the carbon nanohorn aggregates 3, the carbon nanohorn aggregate 3 aggregates are present. Since the conductivity of the conductive particles 4 is much higher than that of the curable resin 5, the conductive connection of the conductive particles 4 can be formed.

  As a result, the conductive paste 1 has a high conductivity compared to when carbon nanotubes are used by uniformly dispersing the carbon nanohorn aggregates 3 and using the high conductivity of each carbon nanohorn 2. Can be realized.

  [Embodiment 1] The present embodiment will be described more specifically with reference to the following examples and comparative examples. However, the invention is not limited by the following examples.

  The carbon nanohorn aggregate 3 in Example 1 was prepared by irradiating a graphite rod not containing a metal catalyst with CO2 laser light in a room temperature argon gas atmosphere. The diameter of the carbon nanohorn aggregate 3 was about 50 to 200 nm, the diameter of one carbon nanohorn 2 was 0.7 to 3 nm, and the length was 10 to 100 nm.

  When the carbon nanohorn aggregate 3 is mixed and kneaded with conductive particles 4 made of silver particles and a three-roll mill to make the silver particles 100 parts by weight, the carbon nanohorn aggregate 3 is 0.5 parts by weight and the epoxy resin is 5 parts by weight. A conductive paste 1 composed of 1 part by weight and 1 part by weight of a curing agent was produced. After the conductive paste 1 was cured at 150 ° C., the specific resistance was measured. The results are shown in Table 1.

  [Example 2] The carbon nanohorn aggregate 3 in Example 2 was obtained by adding a carbon nanohorn aggregate to a silver paste obtained by mixing and kneading 100 parts by weight of silver particles, 5 parts by weight of an epoxy resin, and 1 part by weight of a curing agent with a three-roll mill. Thereafter, 0.5 part by weight of No. 3 was added and mixed and kneaded by a three-roll mill to produce a conductive paste 1. After the conductive paste 1 was cured at 150 ° C., the specific resistance was measured. The results are shown in Table 1.

  As a comparison with Example 1, Example 2 is a conductive paste prepared by kneading a carbon nanohorn aggregate simultaneously with other materials, whereas Example 2 is a silver paste first. This is a conductive paste prepared by kneading a carbon nanohorn aggregate later on a silver paste prepared by kneading.

  [Comparative Example 1] A conductive paste 1 consisting of 5 parts by weight of an epoxy resin and 1 part by weight of a curing agent is mixed and kneaded by a three-roll mill with respect to 100 parts by weight of silver particles, and cured at 150 ° C. Thereafter, the specific resistance was measured. The results are shown in Table 1. As a comparison with Example 1, Comparative Example 1 does not use the carbon nanohorn aggregate 3.

  [Comparative Example 2] Manufactured by mixing and kneading a conductive paste composed of 0.5 parts by weight of carbon nanotubes, 5 parts by weight of epoxy resin, and 1 part by weight of a curing agent with a three-roll mill with respect to 100 parts by weight of silver particles. Then, after curing at 150 ° C., the specific resistance was measured. The results are shown in Table 1. As a comparison with Example 1, Comparative Example 2 uses carbon nanotubes instead of the carbon nanohorn aggregate 3.

[Results of Examination of Examples and Comparative Examples] From the results shown in Table 1, the conductive paste 1 of Examples 1 and 2 has a specific resistance of 1 after low-temperature curing by mixing the carbon nanohorn aggregate 3. It was found to be 8 × 10 ⁻⁵ (Ω · cm).

On the other hand, the conductive paste 1 of Comparative Example 1 that does not include the carbon nanohorn aggregate 3 and is composed of silver particles that are the conductive particles 4 has a specific resistance of 9.0 × 10 ⁻⁵ (Ω · cm). In addition, the conductive paste 1 of Comparative Example 2 containing carbon nanotubes had a specific resistance of 8.4 × 10 ⁻⁵ (Ω · cm).

  That is, it can be seen that the conductive paste 1 of Example 1 has a greater effect of reducing the specific resistance than the conductive paste 1 of Comparative Example 1 and Comparative Example 2. That is, when the carbon nanohorn aggregate 3 is mixed with the conductive paste 1, the specific resistance can be reduced and high conductivity can be realized as compared with the case where the carbon material is not mixed or the case where the carbon nanotube is mixed. Can do.

  [Second Embodiment] Next, a second embodiment will be described in detail.

  [Description of Structure] The conductive paste 1 in this embodiment is different from the first embodiment in the composition ratio of the carbon nanohorn aggregate 3, the conductive particles 4, and the curable resin 5. Other structures and experimental conditions are the same as those in the first embodiment. That is, the conductive paste 1 according to the second embodiment includes the carbon nanohorn aggregate 3, the conductive particles 4, and the curable resin 5 in which the carbon nanohorns 2 are gathered radially with the conical tip portion outside. ing.

  The composition ratio of the conductive paste 1 in the present embodiment is such that the carbon nanohorn aggregate 3 is in the range of 0.01 to 30 parts by weight when the conductive particles 4 are 100 parts by weight. The curable resin 5 needs to be contained in the conductive paste 1 more than the carbon nanohorn aggregate 3.

  Hereinafter, examples and comparative examples in the present embodiment will be described.

  As an example, the carbon nanohorn 2 was prepared by irradiating a graphite rod not containing a metal catalyst with CO2 laser light in a room temperature argon gas atmosphere. The diameter of the carbon nanohorn aggregate 3 was about 50 to 200 nm, the diameter of one carbon nanohorn 2 was 0.7 to 3 nm, and the length was 10 to 100 nm.

  [Example 1] Example 1 is an example of the composition ratio of the present embodiment. The composition ratio of silver particles is 100 parts by weight, carbon nanohorn aggregate 3 is 0.5 parts by weight, and epoxy resin is 5 parts by weight. It is the electrically conductive paste 1 comprised by weight part and 1 weight part of hardening | curing agents. The results are shown in Table 2.

  [Example 3] As Example 3, the carbon nanohorn aggregate 3 was mixed and kneaded with conductive particles 4 made of silver particles and a three roll mill, and the carbon nanohorn aggregate 3 was 0 with respect to 100 parts by weight of silver particles. A conductive paste 1 composed of 0.01 parts by weight, 5 parts by weight of an epoxy resin, and 1 part by weight of a curing agent was produced. After the conductive paste 1 was cured at 150 ° C., the specific resistance was measured. The results are shown in Table 2.

  [Example 4] As Example 4, the carbon nanohorn aggregate 3 was mixed and kneaded with conductive particles 4 made of silver particles and a three-roll mill, and the carbon nanohorn aggregate 3 was 2 parts per 100 parts by weight of silver particles. A conductive paste 1 composed of 5 parts by weight, 5 parts by weight of an epoxy resin, and 1 part by weight of a curing agent was produced. After the conductive paste 1 was cured at 150 ° C., the specific resistance was measured. The results are shown in Table 2.

  [Example 5] As Example 5, the carbon nanohorn aggregate 3 was mixed and kneaded with conductive particles 4 made of silver particles and a three-roll mill, and the carbon nanohorn aggregate 3 was 4 parts per 100 parts by weight of silver particles. A conductive paste 1 composed of 10 parts by weight, 10 parts by weight of an epoxy resin, and 1 part by weight of a curing agent was produced. After the conductive paste 1 was cured at 150 ° C., the specific resistance was measured. The results are shown in Table 2.

  [Example 6] As Example 6, the carbon nanohorn aggregate 3 was mixed and kneaded with conductive particles 4 made of silver particles and a three-roll mill, and the carbon nanohorn aggregate 3 was 15 parts per 100 parts by weight of silver particles. A conductive paste 1 composed of 50 parts by weight, 50 parts by weight of an epoxy resin, and 5 parts by weight of a curing agent was produced. After the conductive paste 1 was cured at 150 ° C., the specific resistance was measured. The results are shown in Table 2.

  [Example 7] As Example 7, the carbon nanohorn aggregate 3 was mixed and kneaded with conductive particles 4 made of silver particles and a three-roll mill, and the carbon nanohorn aggregate 3 was 30 parts per 100 parts by weight of silver particles. A conductive paste 1 composed of 100 parts by weight, 100 parts by weight of an epoxy resin, and 10 parts by weight of a curing agent was produced. After the conductive paste 1 was cured at 150 ° C., the specific resistance was measured. The results are shown in Table 2.

  [Comparative Example 3] As Comparative Example 3, a conductive material composed of 0.001 part by weight of carbon nanohorn aggregate 3, 5 parts by weight of epoxy resin, and 1 part by weight of a curing agent with respect to 100 parts by weight of silver particles. The specific paste was measured by mixing and kneading the functional paste 1 with a three-roll mill and curing at 150 ° C. The results are shown in Table 2.

  [Comparative Example 4] As Comparative Example 4, a conductive paste comprising 100 parts by weight of silver particles, 100 parts by weight of carbon nanohorn aggregate 3, 100 parts by weight of epoxy resin, and 10 parts by weight of a curing agent. 1 was produced by mixing and kneading with a three-roll mill, cured at 150 ° C., and then the specific resistance was measured. The results are shown in Table 2.

From the results of Table 2, in Examples 1 to 7 in which the composition ratio of the carbon nanohorn aggregate 3 is 0.01 to 30 parts by weight, the specific resistance after low-temperature curing is 3.1 × 10 ⁻⁵ (Ω · cm). It turns out that it becomes a smaller value.

On the other hand, the conductive paste 1 of Comparative Example 3 in which the carbon nanohorn aggregate 3 is 0.001 part by weight has a specific resistance of 8.2 × 10 ⁻⁵ (Ω · cm) and is 100 parts by weight. The conductive paste 1 of No. 4 had a specific resistance of 8.9 × 10 ⁻⁵ (Ω · cm).

  That is, it can be seen that the conductive pastes 1 of Examples 1 to 7 have a greater effect of reducing the specific resistance than the conductive pastes 1 of Comparative Example 3 and Comparative Example 4. As a result, the electroconductive paste 1 can implement | achieve high electroconductivity, when the composition ratio of nanohorn is 0.01-30 weight part.

  [Third Embodiment] [Application to Substrate] Next, a third embodiment will be described in detail.

  [Description of Structure] In this embodiment, the conductive paste 1 composed of the carbon nanohorn aggregate 3, the conductive particles 4, and the curable resin 5 in the first and second embodiments is formed on the circuit pattern 7 of the substrate 6. A case where the electronic component 9 is mounted on the substrate 6 will be described.

  In this embodiment, the conductive paste 1 shown in the first and second embodiments and a substrate 6 are provided. Other structures and experimental conditions are the same as those in the first and second embodiments. That is, the conductive paste 1 according to the third embodiment includes the carbon nanohorn aggregate 3, the conductive particles 4, and the curable resin 5 in which the carbon nanohorns 2 are gathered radially with the conical tip portion outside. ing.

  As shown in the second embodiment, the composition ratio of the conductive paste 1 is preferably 0.01 to 30 parts by weight of the carbon nanohorn aggregate 3 with respect to 100 parts by weight of the conductive particles 4. The curable resin 5 needs to be contained in the conductive paste 1 more than the carbon nanohorn aggregate 3.

  The substrate 6 is made of various materials selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyimide, thermoplastic resin, epoxy, thermosetting resin, aramid nonwoven fabric, glass woven fabric, and glass fabric woven fabric. You can, but you are not limited to this.

  The conductive paste 1 in this embodiment is arranged in a predetermined pattern on the surface of the substrate 6, and a circuit pattern 7 is formed on the substrate 6. The circuit pattern 7 forms a desired circuit board by further connecting various corresponding electronic components 9 and the like in the same manner as a general wiring formed with a copper foil on the board 6. Further, the electronic component 9 can be mounted on the substrate 6 by arranging the electronic component 9 on the circuit pattern 7 in such a positional relationship that the electrodes correspond to each other.

  [Method of Forming on Substrate] Next, a method of forming the conductive paste 1 on the surface of the substrate 6 will be described. FIG. 3 is a process diagram when the conductive paste 1 is supplied to the surface of the substrate 6.

  As shown in FIG. 3A, a substrate 6 is prepared.

  As shown in FIG. 3B, a mask 8 serving as a negative of the circuit pattern 7 is placed on the substrate 6, and the conductive paste 1 is supplied onto the mask 8. As a method of forming a pattern with the conductive paste 1 on the substrate 6, various methods such as screen printing, ink jet, dispenser, impregnation, spin coating and the like can be used.

  Each component (carbon nanohorn aggregate 3, conductive particles 4) of the conductive paste 1 is dispersed in the curable resin 5. In the above state, since the carbon nanohorn aggregates 3 and the respective conductive particles 4 are appropriately spaced, no contact between the carbon nanohorn aggregates 3 and the conductive particles 4 is formed. .

  As shown in FIG. 3C, after the conductive paste 1 is formed on the substrate 6 and the mask 8 is removed, heat, light, etc. are applied to the circuit pattern 7 of the conductive paste 1 to reduce the reducing agent. Activate. The conductive paste 1 is cured in the pattern, thereby forming a desired circuit pattern 7 on the substrate 6.

  As the curing of the curable resin 5 proceeds, the entire volume of the curable resin 5 contracts as shown in FIG. As a result, the distance between the carbon nanohorn aggregate 3 and each conductive particle 4 is reduced. The carbon nanohorn aggregate 3 enters between the narrowed conductive particles 4 and can serve as a conductive path of the conductive particles 4. As a result, the entire carbon nanohorn aggregate 3 can be brought into contact as a conductive component, and the conductive particles 4 can form a conductive connection throughout the carbon nanohorn aggregate 3.

  Further, as shown in FIG. 3D, the circuit pattern 7 may be attached in such a positional relationship that the electrodes (or terminals) of the electronic component 9 correspond to each other. The conductive paste 1 can be mounted on the substrate 6 by curing the conductive paste 1 by raising the temperature to a predetermined temperature or placing it for a predetermined time as necessary. .

  [Explanation of Effects] A mode in which heat, light or the like is applied to the conductive paste 1 after the conductive paste 1 is supplied to the surface of the substrate 6 will be described. As shown in FIG. 4, since the curing reaction of the curable resin has not yet started in the process of supplying the conductive paste 1, the operation of supplying the conductive paste 1 is compared in terms of time, supply operation, supply means, etc. Can have a high degree of freedom.

  In this case, the conductive paste 1 has sufficient fluidity, and the conductive paste 1 can be supplied to the surface of the substrate 6 in a predetermined pattern by a general printing means. For example, as shown in FIG. 3B, a mask 8 serving as a negative of the circuit pattern 7 can be placed on the substrate 6, and the conductive paste 1 can be supplied onto the mask 8.

  When heat, light, or the like is applied to the pattern of the conductive paste 1 in this embodiment, the conductive paste 1 is cured in the pattern, and a desired circuit pattern 7 can be formed on the circuit board. The circuit pattern 7 can form a desired circuit board by connecting various corresponding electronic components 9 in the same manner as a general wiring formed of copper foil on the board. Further, the electronic component 9 can be mounted on the substrate 6 by mounting the electronic component 9 on the circuit pattern 7 in such a positional relationship that the electrodes correspond to each other.

  When the conductive paste 1 of the present embodiment is formed on the substrate 6 as the circuit pattern 7, high adhesive strength can be realized with respect to the substrate 6. Therefore, a highly reliable circuit board can be formed.

  In addition, the conductive paste 1 of the present embodiment can be used even when the circuit pattern 7 is printed on the substrate 6, the electronic component 9 is disposed, and the electronic component 9 is mounted by raising the temperature to a predetermined temperature. 6 and the electronic component 9 can have high adhesive strength.

DESCRIPTION OF SYMBOLS 1 Conductive paste 2 Carbon nanohorn 3 Carbon nanohorn aggregate | assembly 4 Conductive particle 5 Curable resin 6 Board | substrate 7 Circuit pattern 8 Mask 9 Electronic component

Claims (8)

  A conductive paste comprising 0.01 to 30 parts by weight of a carbon nanohorn aggregate with respect to 100 parts by weight of conductive particles, and more curable resin than the carbon nanohorn.   The conductive particles according to claim 1, wherein the conductive particles are composed of silver, copper, gold, tin, indium, nickel, palladium, or a mixture or alloy of a plurality of particles selected from these groups. paste.   The conductive paste according to claim 1, wherein the curable resin is a thermosetting resin.   The conductive paste according to claim 1, wherein the curable resin is a photocurable resin.   5. The curable resin is selected from the group consisting of an epoxy resin, an acrylic resin, a phenol resin, a polyimide resin, a silicone resin, a urethane resin, and an unsaturated polyester resin. The conductive paste as described. It is a manufacturing method of the electrically conductive paste according to claim 1 thru / or 5,
A method for producing a conductive paste in which the conductive particles, the carbon nanohorn aggregate, and the curable resin material are mixed and kneaded simultaneously. It is a manufacturing method of the electrically conductive paste according to claim 1 thru / or 5,
Mixing and kneading the conductive particles and the curable resin to produce a conductive paste,
A method for producing a conductive paste, in which a carbon nanohorn aggregate is mixed and kneaded into the conductive paste later.   A circuit board comprising a circuit pattern formed from the conductive paste according to claim 1.

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