TWI830865B - Conductive adhesive - Google Patents

Abstract

This invention provides a conductive adhesive with high fluidity and conductivity.

The conductive adhesive of this invention contains: (A) conductive particle, (B) a solvent, (C) a thermosetting resin and (D) silica particles with an average particle size of 1 to 50nm.

Description

Conductive adhesive

The present invention relates to, for example, conductive adhesives used for fixing electronic components.

In electronic equipment and electrical equipment, tiny electronic components such as camera modules and light emitting diodes (LED: Light Emitting Diode) must be fixed. In order to fix tiny electronic parts, conductive adhesives are used.

For example, Patent Document 1 describes a composition used for adhesives or sealants, which contains: a molecular weight of 300 to 150,000 g/mol, and a viscosity of 1000 to 100000 mPa‧ at 25°C in a 5 rpm viscometer. sec of siloxane polymer; and a hardener that promotes the hardening of the siloxane polymer when exposed to ultraviolet rays. In addition, Patent Document 1 describes that this material can be used in an LED device.

[Prior technical literature]

[Patent Document]

[Patent Document 1] Japanese Patent Publication No. 2017-525834

In electronic and electrical equipment, conductive adhesives are used to fix tiny electronic parts such as camera modules and light-emitting diodes (LEDs).

For example, when a camera module is installed in a machine, a bracket is used to accommodate the camera module. The installation of the camera module adopts the active alignment method.

In the active calibration method, the bracket first adjusts the position of the camera module relative to the bracket. Then, the camera module is fixed to the bracket using a temporary fixing adhesive. Specifically, a temporary fixing adhesive is introduced, and after the position of the camera module is adjusted and positioned, the temporary fixing adhesive is UV-cured to fix the camera module at a predetermined position relative to the bracket.

Next, a conductive adhesive is introduced between the camera module and the bracket. By introducing a conductive adhesive, conductivity can be obtained between the camera module and the bracket, so that the camera module can be grounded relative to the bracket.

Finally, the gap between the camera module and the bracket is filled by introducing the bracket filling adhesive to finally fix the camera module. Since the gap between the camera module and the bracket is small, the adhesive used to fill the bracket needs to have high fluidity. Therefore, in the active calibration method, three types of adhesives are required: a temporary fixing adhesive, a conductive adhesive, and a bracket filling adhesive.

In recent years, there has been an increasing demand for injecting adhesive into smaller-sized gaps for bonding of photographic modules. In the past, adhesives used to inject into small-sized gaps were limited to insulating adhesives. Since the conductive adhesive contains a large amount of conductive filler (for example, metal particles) for imparting conductivity, the fluidity is low. Therefore, conductive adhesives have not been used as adhesives to be injected into small-sized gaps.

On the other hand, in order to reduce the manufacturing cost of electronic equipment and electrical equipment, electronic components must be mounted more simply. When the fluidity of the conductive adhesive is high, the above-mentioned active calibration method , there is a possibility that the conductive adhesive and the bracket filling adhesive can be replaced by a single type of conductive adhesive. That is, by using a highly fluid conductive adhesive, the steps of grounding the camera module to the bracket and the step of finally fixing the camera module can be performed in one step. The possibility of several steps can be expected to reduce manufacturing costs.

Therefore, an object of the present invention is to provide a conductive adhesive having high fluidity and conductivity.

In order to solve the above-mentioned problems, the present invention has the following configuration.

(composition 1)

Structure 1 of the present invention is a conductive adhesive containing: (A) conductive particles, (B) solvent, (C) thermosetting resin, and (D) silica particles with an average particle diameter of 1 to 50 nm. .

According to the configuration 1 of the present invention, a conductive adhesive having high fluidity and conductivity can be obtained. In particular, it is possible to provide a conductive adhesive that can maintain high fluidity even after the conductive adhesive is jet dispensed.

(composition 2)

The composition 2 of the present invention is the conductive adhesive as described in the composition 1, wherein the total of (A) conductive particles, (B) solvent, (C) thermosetting resin and (D) silica particles is 100 In parts by weight, it contains 1 to 20 parts by weight of (D) silica particles.

By containing a predetermined amount of silica particles, the electrically conductive adhesive of Structure 2 of the present invention can have imparted electrical conductivity and high fluidity.

(composition 3)

Structure 3 of the present invention is the conductive adhesive as described in Structure 1 or 2, wherein (D) silica particles are mixed with (C) thermosetting resin in advance.

As in the configuration 3 of the present invention, by mixing the silica particles with the thermosetting resin in advance, it is easy to mix them uniformly with the conductive particles. In addition, the conductive adhesive can have higher fluidity.

(Constitution 4)

The composition 4 of the present invention is the conductive adhesive as described in any one of compositions 1 to 3, wherein (A) conductive particles, (B) solvent, (C) thermosetting resin and (D) average When the total amount of silica particles having a particle diameter of 1 to 50 nm is 100 parts by weight, 0.5 to 15 parts by weight of the solvent (B) is contained.

According to the configuration 4 of the present invention, by making the conductive adhesive contain a predetermined amount of solvent, the handleability of the conductive adhesive becomes excellent, and the fluidity of the conductive adhesive can be more reliably obtained.

(Constitution 5)

Structure 5 of the present invention is the conductive adhesive agent according to any one of Structures 1 to 4, wherein (A) the conductive particles are silver particles.

According to the structure 5 of the present invention, since the electrical conductivity of silver is higher than that of other metals, a conductive adhesive with higher electrical conductivity can be obtained.

(composition 6)

Structure 6 of the present invention is the conductive adhesive agent according to any one of Structures 1 to 5, wherein the solvent (B) contains aromatic hydrocarbons.

According to the configuration 6 of the present invention, by making the solvent contain aromatic hydrocarbons, the handleability of the conductive adhesive becomes excellent, and the fluidity of the conductive adhesive can be more reliably obtained.

(composition 7)

Component 7 of the present invention is the conductive adhesive as described in any one of Components 1 to 6, wherein (C) The thermosetting resin contains epoxy resin or acrylic resin.

According to the configuration 7 of the present invention, by making the thermosetting resin contain an epoxy resin or an acrylic resin, the electronic component to be fixed can be fixed more reliably.

(composition 8)

The composition 8 of the present invention is a conductive adhesive for photographic modules, which contains the conductive adhesive described in any one of compositions 1 to 7.

The conductive adhesive of the present invention has both high fluidity and established conductivity. Therefore, the conductive adhesive of the present invention can meet the fluidity and conductivity requirements required for fixing the photographic module.

(Composition 9)

The constitution 9 of the present invention is a conductive adhesive for spray dispensing, which contains the conductive adhesive described in any one of constitutions 1 to 7.

The conductive adhesive of the present invention has high fluidity. Therefore, the conductive adhesive of the present invention can be preferably used for spray dispensing.

According to the present invention, a conductive adhesive having high fluidity and conductivity can be provided. According to the present invention, in particular, it is possible to provide a conductive adhesive that can maintain high fluidity even after the conductive adhesive is sprayed and dispensed.

12:Glass plate

14: Stainless steel plate

16: Spacer

20: Conductive adhesive

22:Glass plate

24:Electrode

50:Jet dispenser

52: Needle

54: Seals (sealing components)

56:Nozzle

R: Resistance meter

S: itinerary

Figure 1 is a schematic diagram of an auxiliary tool (jig, also called a jig) used to measure the fluidity of a conductive adhesive, viewed from the side.

Figure 2 is a schematic diagram of an auxiliary tool for measuring the fluidity of conductive adhesives viewed from above.

3 is a schematic diagram showing the arrangement of electrodes and conductive adhesive for measuring the resistance of the conductive adhesive.

4 is a schematic cross-sectional view of an example of a jet dispensing device (jet dispenser).

The embodiments of the present invention will be described in detail below with reference to the drawings. The following embodiments are embodiments of the present invention and do not limit the scope of the present invention.

The conductive adhesive according to the embodiment of the present invention contains: (A) conductive particles, (B) solvent, (C) thermosetting resin, and (D) silica particles. (D) The average particle diameter of the silica particles is 1 to 50 nm. According to this embodiment, a conductive adhesive having high fluidity and conductivity can be obtained.

〈(A) Conductive particles〉

The conductive adhesive agent of this embodiment contains (A) conductive particles as conductive particles. The conductive particles are not particularly limited, and conductive metal particles can be used. The type of metal of the metal particles may be silver (Ag), gold (Au), copper (Cu), nickel (Ni), palladium (Pd), platinum (Pt), tin (Sn) and alloys thereof. As the conductive particles, one type of metal particles or alloy particles may be used alone, or two or more types of metal particles or alloy particles may be used in combination.

In the embodiment of the present invention, the conductive particles are preferably silver particles or alloy particles containing silver, and are particularly preferably silver particles. Silver has a higher electrical conductivity than other metals. By using silver particles as conductive particles, a conductive adhesive with higher conductivity can be obtained.

The shape of the conductive particles is not particularly limited. For example, spheres, granules, and flakes can be used (flake, or fragment-like) or scale-like conductive particles.

The average particle diameter of the conductive particles is preferably 0.1 μm to 50 μm, particularly preferably 0.1 μm to 10 μm, more preferably 0.1 μm to 7 μm, most preferably 0.1 μm to 5 μm. The average particle diameter here means the volume-based median diameter (d50) obtained by a laser diffraction scattering particle size distribution measurement method.

The method of producing conductive particles is not particularly limited, and may be produced by, for example, a reduction method, a grinding method, an electrolysis method, an atomization method, a heat treatment method, or a combination of these. For example, silver particles can also be produced by these production methods. Flaky silver particles can be produced by crushing spherical or granular silver particles using a ball mill or the like.

〈(B) Solvent〉

The conductive adhesive agent of this embodiment contains (B) solvent. Examples of the solvent include alcohols such as methanol, ethanol, and isopropyl alcohol (IPA: Isopropyl Alcohol); organic acids such as vinyl acetate; and aromatic hydrocarbons such as solvent naphtha, cyclohexane, toluene, and xylene. ; N-alkylpyrrolidinones such as N-Methyl-2-Pyrrolidone (NMP: N-Methyl-2-Pyrrolidone); N,N-dimethylformamide (DMF: N,N- Amides such as Dimethyl Formamide); ketones such as methyl ethyl ketone (MEK: Methyl Ethyl Ketone); cyclic carbonates such as terpineol (TEL: Terpineol) and butyl carbitol (BC: Butyl Carbitol) ; and water, etc.

In the conductive adhesive of this embodiment, the solvent (B) preferably contains aromatic hydrocarbons. In order to more reliably obtain a conductive adhesive excellent in handleability and fluidity, it is preferable to use mineral spirits or cyclohexane as an aromatic hydrocarbon.

The content of the solvent is not particularly limited. In order to more reliably obtain a conductive adhesive excellent in handleability and fluidity, the total weight of (A) conductive particles, (B) solvent, (C) thermosetting resin, and (D) silica particles is 100 parts by weight, the conductive adhesive preferably contains 0.5 to 15 parts by weight (B) The solvent preferably contains 1 to 14 parts by weight, more preferably 2 to 13 parts by weight.

〈(C) Thermosetting resin〉

The conductive adhesive of this embodiment contains (C) thermosetting resin. The thermosetting resin joins and fixes the object to be adhered, and also joins (A) conductive particles and (D) silica particles which are inorganic materials in the conductive adhesive.

Examples of the thermosetting resin include cellulose-based resins such as ethyl cellulose and nitrocellulose, acrylic resin, alkyd resin, saturated polyester resin, butyral resin, polyvinyl alcohol, and hydroxypropyl resin. Cellulose etc. These resins can be used individually or in mixture of 2 or more types.

The conductive adhesive of this embodiment preferably contains epoxy resin or acrylic resin as (C) thermosetting resin. By containing an epoxy resin or an acrylic resin in the thermosetting resin, electronic components to be fixed can be fixed more reliably.

The content of the thermosetting resin (C) is preferably 30 to 80 parts by weight, more preferably 35 to 75 parts by weight, and more preferably 40 to 70 parts by weight relative to 100 parts by weight of the conductive particles (A). When the content of the thermosetting resin in the conductive adhesive is within the above range, the objects to be bonded can be reliably joined and fixed. In addition, (A) conductive particles and (D) silica particles, which are inorganic materials in the conductive adhesive, can be joined and fixed, and the predetermined conductivity brought by the (A) conductive particles can be maintained. .

〈(D) Silica particles〉

The conductive adhesive of this embodiment contains (D) silicon dioxide particles with an average particle diameter of 1 to 50 nm. By setting the average particle diameter of the silica particles to 1 to 50 nm, the conductive adhesive of this embodiment can have high fluidity. In particular, by containing silica particles with an average particle diameter of 1 to 50 nm, high fluidity can be maintained even after the conductive adhesive is sprayed and dispensed. Jet dispensing is a supply method that gives a large impact to the conductive adhesive. In the conductive adhesive of this embodiment, nanometer dioxide Silicon is considered to have the effect of mitigating the impact exerted on the conductive adhesive during jet dispensing.

The shape of the silica particles may be spherical or other than spherical. From the viewpoint of maintaining high fluidity, the shape of the silica particles contained in the conductive adhesive of this embodiment is preferably spherical. The manufacturing method of silica particles is not particularly limited. Silica particles produced by a generally known method such as thermal spraying can be used.

Since the average particle diameter of the silica particles contained in the conductive adhesive of this embodiment is in the nanometer range, it is difficult to measure the particle diameter by a laser diffraction scattering particle size distribution measuring method. By taking a TEM (Transmitting Electron Microscope) picture of silica particles, measuring the particle diameters of 50 silica particles in the TEM picture and calculating the average, it can be set as the average of the silica particles. particle size. The particle size of the silica particles can be determined by taking the maximum size of the silica particles in the TEM photograph as the particle size of the silica particles. The particle size of silica particles can be measured using commonly known image processing software.

When the total of (A) conductive particles, (B) solvent, (C) thermosetting resin and (D) silica particles is 100 parts by weight, the conductive adhesive according to the embodiment of the present invention is preferably It contains 1 to 20 parts by weight of (D) silica particles, preferably 1 to 10 parts by weight, more preferably 1 to 5 parts by weight. By containing a predetermined amount of silica particles, the conductive adhesive according to the embodiment of the present invention can have imparted conductivity and high fluidity.

The (D) silica particles contained in the conductive adhesive according to the embodiment of the present invention are preferably mixed with the (C) thermosetting resin in advance. As in the embodiment of the present invention, by mixing the silica particles with the thermosetting resin in advance, higher fluidity can be achieved. The type in which silica particles are mixed with thermosetting resin in advance is sometimes called the resin particle type (Master Batch, also known as masterbatch).

〈Other ingredients〉

The conductive adhesive of this embodiment may contain other additives, such as those appropriately selected from the group consisting of dispersants, rheology modifiers, pigments, and the like.

<Viscosity of conductive adhesive>

The initial viscosity (viscosity immediately after production) of the conductive adhesive of this embodiment is preferably 0.1 to 10 (Pa‧s). In addition, the viscosity of the conductive adhesive of this embodiment 24 hours after production (viscosity after 24 hours) is preferably 0.1 to 10 (Pa‧s). In addition, the ratio of the initial viscosity to the viscosity after 24 hours ("viscosity after 24 hours"/"initial viscosity", called "viscosity increase ratio after 24 hours") is preferably 0.9 to 1.4, particularly preferably 1.0 to 1.3. By setting the initial viscosity, the viscosity after 24 hours, and the viscosity increase rate after 24 hours of the conductive adhesive of this embodiment within a predetermined range, it is possible to have high fluidity and suppress changes in viscosity over time. Therefore, the electrical conductivity of this embodiment results in good handleability as a product, and high fluidity can be maintained.

The viscosity of the conductive adhesive of this embodiment after spraying is preferably 0.2 to 15 (Pa‧s), particularly preferably 0.5 to 10 (Pa‧s). Even after spray dispensing, the viscosity of the conductive adhesive in this embodiment can be kept low, so the conductive adhesive can be placed in a narrow gap by spray dispensing.

The viscosity of the above-mentioned conductive adhesive can be measured using a viscometer (Type B) manufactured by Brookfield Engineering at a temperature of 25° C. and a rotation speed of 10 rpm.

〈Method for manufacturing conductive adhesive〉

The conductive adhesive of this embodiment can be produced by mixing the above components using, for example, a crusher, a ball mill, a three-roller mill, a rotary mixer, and/or a biaxial blender.

〈Use of conductive adhesive〉

Next, the use of the conductive adhesive according to this embodiment will be described. Conductive adhesive of this embodiment It can be used as a sealing material and/or electrode by coating it on a predetermined location. The coating method is arbitrary, and for example, generally known methods such as dispensing, jet dispensing, stencil printing, screen printing, pin plate transfer, and imprinting can be used for coating.

After the conductive adhesive of this embodiment is applied to a predetermined position, the applied conductive adhesive can be hardened by heat treatment. The heat treatment can be performed by raising the temperature to 60 to 100°C for 20 to 40 minutes, and then maintaining the raised temperature for 50 to 70 minutes for hardening. Specifically, the temperature can be raised to 80°C for 30 minutes, and then the temperature can be maintained at 80°C for 60 minutes for hardening.

The conductive adhesive of this embodiment can be used as a conductive adhesive for photographic modules. The conductive adhesive of the present invention has both high fluidity and established conductivity. Therefore, the conductive adhesive of the present invention can meet the fluidity and conductivity requirements required for fixing the photographic module.

The conductive adhesive of this embodiment can be preferably used as a conductive adhesive for spray dispensing. The conductive adhesive of this embodiment has high fluidity even after injection dispensing. Therefore, the camera module can be fixed by spray dispensing, so it can be used optimally.

Figure 4 shows a schematic cross-sectional view of the jet dispensing device (jet dispenser 50). The jet dispenser 50 has a needle 52 that can move back and forth like a piston; a seal 54 (sealing member) that prevents the conductive adhesive 20 from leaking to the outside even if the needle 52 moves back and forth; and A nozzle 56 for spraying and dispensing the conductive adhesive 20 . As shown in FIG. 4( a ), by moving the needle 52 back and forth along the length of the stroke S, the conductive adhesive 20 is supplied to the spray dispenser 50 and is sprayed and dispensed from the nozzle 56 . The nozzle 56 has an injection needle-like shape with an inner diameter of 100 to 200 μm. As a result, as shown in FIG. 4(b) , the conductive adhesive 20 sprayed and dispensed from the nozzle 56 is supplied to the predetermined object. Since the conductive adhesive of this embodiment has high fluidity even after spraying and dispensing, the conductive adhesive 20 can be supplied to a narrow gap.

The jet dispenser 50 can perform hundreds of drops of jet dispensing within 1 second by the back and forth movement of the needle 52 . Therefore, a large impact is exerted on the conductive adhesive 20 . Even after such a large impact is applied, the conductive adhesive 20 of this embodiment can maintain fluidity.

The adhesive used for fixing the camera module to the bracket is supplied by jet dispensing. In recent years, in order to attach the camera module to the bracket, there has been an increasing demand for injecting adhesive into a smaller gap. Specifically, the gap between the bracket and the camera module is hundreds of μm (for example, 600 μm), and the adhesive must be injected covering a length of several mm. If the conductive adhesive of this embodiment is sprayed and dispensed after the camera module is fixed to the bracket with the temporary fixing adhesive, the conductive adhesive can be supplied (injected) to the camera module and Small gaps between brackets. Since the conductive adhesive of this embodiment has conductivity, it has two functions: a conductive adhesive (grounding adhesive) and a bracket filling adhesive (sealing adhesive). Therefore, the conductive adhesive of this embodiment can be used as a single type of adhesive instead of two types of adhesives, the conductive adhesive and the bracket filling adhesive.

As described above, by using the conductive adhesive of this embodiment that has high fluidity and conductivity, it is possible to obtain the grounding of the camera module with respect to the bracket in one step, and The possibility of finally fixing the camera module in two steps can be expected to reduce manufacturing costs.

The resistivity ρ of the conductive adhesive of this embodiment is preferably 1×10 ^-4 to 5×10 ^-1 Ω‧cm. Since the conductive adhesive of this embodiment is preferably used for the purpose of obtaining sealing and conductivity, high conductivity is not required.

Since the conductive adhesive of this embodiment can be supplied to a small-sized gap, it can be preferably used to fix tiny components such as camera modules and image sensor modules at a predetermined location of the device. In addition, since the conductive adhesive of this embodiment can be used for sealing and bonding of narrow gaps, Therefore, it can be used in the circuit formation and electrode formation of electronic components such as chip resistors and light-emitting diodes (LEDs), as well as in the bonding of electronic components to substrates.

[Example]

Examples and comparative examples of the present invention will be described below.

[Preparation of conductive adhesive]

The following components were mixed at the ratios shown in Tables 1 to 3 to prepare conductive adhesives of Examples and Comparative Examples. The ratios of each component shown in Tables 1 to 3 are all expressed in parts by weight.

(A)Silver particles

(Silver particles 1) Flaky particles, average particle diameter 6 μm (manufactured by METALOR, product name: EA-0001)

(Silver particles 2) Spherical particles, average particle diameter 5 μm (manufactured by METALOR Corporation)

(B)Solvent

(Solvent 1) Solvent oil (manufactured by Maruzen Petrochemical Industry Co., Ltd., SW1800)

(Solvent 2) Cyclohexane (manufactured by Fujifilm Wako Pure Chemical Industries, product name: cyclohexane)

(C)Thermosetting resin

(Thermosetting resin 1) Bisphenol F type epoxy resin-bisphenol A type epoxy resin mixture (aromatic epoxy resin) (DIC Co., Ltd., EXA835LV, epoxy equivalent 165)

(Thermosetting resin 2) Aminophenol type liquid epoxy resin (manufactured by Mitsubishi Chemical Co., Ltd., product name: jER630D)

(D)Nano silicon dioxide

(Nano silicon dioxide 1) Average particle size: 10nm, resin particle type treatment (manufactured by Admatechs, product name: YA010AJGP)

(Nano silicon dioxide 2) average particle size: 50nm, resin particle type treatment (manufactured by Admatechs, product name: YA050C-SM1)

(Nano silica 3) average particle size: 10nm, (manufactured by Nippon Aerosil Co., Ltd., product name: R805)

(Silicon dioxide 4) average particle size (D50) 1.5 μm (manufactured by Admatechs, product name: SE5200SEE)

Since Nanosilica 1 and Nanosilica 2 are treated with resin particles, they contain resin components. The blending amounts shown in Tables 1 to 3 show the blending amounts of nanosilica excluding the resin component. In Nanosilica 1 and Nanosilica 2, the weight ratio of nanosilica is 90% by weight of the total resin particle form, and the weight ratio of the resin component is 10% by weight of the total resin particle form. For example, in the case of Example 1, when the silver particles 1 are 100 parts by weight, the compounding amount of nanosilica 1 is 3.8 parts by weight, so the nanosilica 1 after resin particle form treatment is compounded 4.2 Parts by weight, the resin component of Nanosilica 1 is 0.42 parts by weight. The resin components of Nanosilica 1 and Nanosilica 2 are not described in Tables 1 to 3.

other ingredients

(NanoAg) average particle size: 100nm (METALOR Co., Ltd., P620-24)

(Hardening agent) Latent hardener (manufactured by T&K TOKA Co., Ltd., product name: Fujicure FXR-1020)

The conductive adhesive used in the Examples and Comparative Examples was produced by mixing the above-mentioned components with a planetary blender and then dispersing them with a three-roller mill to form a paste.

[Measurement method of viscosity]

The viscosity of the conductive adhesives in Examples and Comparative Examples was measured at a temperature of 25° C. using a viscometer (Type B) manufactured by Brookfield Engineering. The viscosity was measured at a rotation speed of 10 rpm for each of the conductive adhesives of the Examples and Comparative Examples.

The "initial viscosity" in Tables 1 to 3 refers to the viscosity shortly after the conductive adhesive is produced. The measured value when the viscosity is measured under the above conditions. The "viscosity after 24 hours" in Tables 1 to 3 is the measured value when the viscosity was measured under the above conditions shortly after the conductive adhesive was produced and 24 hours after the "initial viscosity" was measured. The "viscosity increase rate after 24 hours (times)" in Tables 1 to 3 is the ratio of "viscosity after 24 hours" to "initial viscosity" ("viscosity after 24 hours"/"initial viscosity"). If the viscosity increase rate (times) after 24 hours is too high, since the conditions when applying the conductive adhesive will change with the passage of time, it is not suitable for those who want to apply the conductive adhesive with good reproducibility. good. If the viscosity increase rate (times) after 24 hours is 1.5 times, it can be regarded as the allowable increase in viscosity.

The "post-JET viscosity" in Tables 1 to 3 refers to the measured value when the conductive adhesive is subjected to a predetermined jet dispensing, the conductive adhesive after the jet dispensing is recovered, and then the viscosity is measured under the above conditions. . If the viscosity after JET is 10.000 (Pa‧s) or less, it can be said that the conductive adhesive can be injected into a small-sized gap, such as a 600 μm gap, by jet dispensing.

[Measurement method of fluidity]

"Fluidity (sec/mm)" in Tables 1 to 3 is an index showing the fluidity of the conductive adhesive 20 after injection and dispensing into a gap of 600 μm. Specifically, the flow rate of the conductive adhesive 20 is measured using an auxiliary tool as shown in FIG. 1 (a schematic view when viewed from the side) and FIG. 2 (a schematic view when viewed from above). That is, as shown in FIGS. 1 and 2 , the glass plate 12 is arranged on the stainless steel plate 14 via the spacer 16 so that the gap d becomes 600 μm, and the conductive adhesive 20 of the Example and the Comparative Example is sprayed. It is dispensed and arranged near the opening of the gap (arrow portion in Fig. 1). The time t (seconds) when the conductive adhesive 20 flows into the gap reaches a predetermined flow distance L (mm) = 20 mm is measured, and the flow time t/L (seconds/mm) per 1 mm is calculated. Let be liquidity. The flowability was measured at 25°C. In the cases of Comparative Example 1 and Comparative Example 2 shown in Table 1, the flow distance L did not reach 20 mm. Therefore, it is recorded as NG (Not Good) in the "Liquidity" column of Table 1, and "stop flow" is stated in parentheses. distance. That is, in the case of the conductive adhesive of Comparative Example 1, the flow stopped at 6 mm, and in the case of the conductive adhesive of Comparative Example 2, the flow stopped at 1 mm.

[Measurement method of resistance]

"Resistance value (Ω)" in Tables 1 to 3 is the measured value of the resistance after hardening the conductive adhesives of Examples and Comparative Examples. The resistance is measured using the electrode 24 shown in FIG. 3 . That is, as shown in FIG. 3 , a pair of strip-shaped electrodes 24 are arranged on the hardened glass plate 12 so that the distance D between the electrodes 24 becomes 40 mm. The conductive adhesives of the Example and the Comparative Example were placed on the glass plate 12 and the pair of electrodes 24 by the stencil printing method so that the width W became 10 mm, and then hardened. The prepared conductive adhesive was heated to 80°C in 30 minutes, and then maintained at 80°C for 60 minutes to harden. The film thickness of the conductive adhesive after hardening is 20 μm. The resistance value between the hardened counter electrodes 24 was measured with a resistance meter R to obtain the resistance values of the examples and comparative examples. The film thickness was measured using a surface roughness and shape measuring machine (model: Surfcom 1500SD-2) manufactured by Tokyo Precision Co., Ltd. In addition, the resistance value was measured using a digital multimeter (model: 2001) manufactured by TFF Keithley Instruments Co., Ltd.

As shown in Table 1, Comparative Examples 1 and 2 caused problems in viscosity and fluidity after JET. That is, the conductive adhesive of Comparative Example 1 without nanosilica has a post-JET viscosity as high as 14.500 (Pa‧s), and does not show good fluidity in the fluidity measurement. That is, as shown in Table 1, in the case of the conductive adhesive of Comparative Example 1, the flow stopped at 6 mm. In addition, the conductive adhesive of Comparative Example 2 with an average particle size of silica having an average particle size of 1.5 μm had a post-JET viscosity as high as 22.375 (Pa‧s), and showed almost no fluidity in the fluidity measurement. That is, as shown in Table 1, in the case of the conductive adhesive of Comparative Example 2, the flow stopped at 1 mm. In addition, as shown in Table 1, the conductive adhesive of Comparative Example 3 with nano-Ag replacing nano-silica has a viscosity as high as 13.375 after 24 hours. The final viscosity increasing rate is also a higher rate of 3.8 times.

On the other hand, as shown in Tables 1 to 3, the post-JET viscosity of the conductive adhesives of Examples 1 to 14 is 0.625 to 9.875 (Pa‧s), which is compared with the conductive adhesives of Comparative Examples 1 and 2. For low viscosity. In addition, the fluidity of the conductive adhesives of Examples 1 to 14 ranged from 49 to 645 seconds/mm, and compared with the conductive adhesives of Comparative Examples 1 and 2 that did not show fluidity, they showed high fluidity. In addition, the viscosity of the conductive adhesives of Examples 1 to 14 after 24 hours is 0.375 to 7.875 (Pa‧s), and the viscosity increase rate after 24 hours is also 1.0 to 1.2 times, which is the same as that of the conductive adhesive of Comparative Example 3. The viscosity after 24 hours and the viscosity increase ratio (times) after 24 hours are in a good range. In addition, the resistance value is also in the range of 1.8 to 850Ω (resistivity ρ is 9.0×10 ^-4 to 4.25×10 ^-1 Ω‧cm), which is an appropriate value for grounding purposes.

From the above description, it can be seen that the conductive adhesives of Examples 1 to 14 having given nanosilica exhibit high fluidity and do not increase in viscosity even after a given time. Therefore, it can be seen that the conductive adhesive of the present invention has high fluidity and conductivity. Therefore, it can be said that the conductive adhesive of the present invention can be suitably used as a conductive adhesive for injection dispensing that is used for fixing, for example, a photographic module.

[Table 1]

[Table 2]

[table 3]

Claims (9)

A conductive adhesive containing: (A) conductive particles with an average particle diameter of 0.1 to 50 μm, (B) solvent, (C) thermosetting resin, and (D) silica particles with an average particle diameter of 1 to 50 nm, Among them, when the total of the aforementioned (A) conductive particles, (B) solvent, (C) thermosetting resin, and (D) silica particles is 100 parts by weight, 0.5 to 15 parts by weight of the aforementioned ( B) solvent, and contains 1 to 20 parts by weight of the aforementioned (D) silica particles, and the content of the aforementioned (C) thermosetting resin is 30 to 80 parts by weight relative to 100 parts by weight of the aforementioned (A) conductive particles. , the viscosity of the aforementioned conductive adhesive after spraying and dispensing is 0.2 to 15Pa. s, the aforementioned viscosity is measured using a B-type viscometer at a temperature of 25°C and a rotation speed of 10 rpm. The conductive adhesive according to claim 1, which contains 100 parts by weight of the total of (A) conductive particles, (B) solvent, (C) thermosetting resin and (D) silica particles. 1 to 10 parts by weight of (D) silica particles. The conductive adhesive according to claim 1 or 2, wherein (D) silica particles are mixed with (C) thermosetting resin in advance. The conductive adhesive according to claim 1 or 2, wherein the total of (A) conductive particles, (B) solvent, (C) thermosetting resin and (D) silica particles is 100 parts by weight. , containing 1 to 14 parts by weight of (B) solvent. The conductive adhesive according to claim 1 or 2, wherein (A) the conductive particles are silver particles. The conductive adhesive according to claim 1 or 2, wherein (B) the solvent contains aromatic Hydrocarbons. The conductive adhesive according to claim 1 or 2, wherein (C) the thermosetting resin contains epoxy resin or acrylic resin. A conductive adhesive for photographic modules, containing the conductive adhesive described in any one of claims 1 to 7. A conductive adhesive for injection dispensing, containing the conductive adhesive according to any one of claims 1 to 7.