JP2007269959A - Electroconductive adhesive, electronic device and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroconductive adhesive hardly increasing connection resistance with time in high temperature high moisture atmospheres even when applied to a base metal terminal electrode or a base metal electrode part, and to provide electronic devices hardly increasing connection resistance with time in high temperature high moisture atmospheres. <P>SOLUTION: The electroconductive adhesive composition comprising (A) an electroconductive metal powder (such as silver powder), and (B) a thermoset/adhesive resin (such as epoxy resin) -based binder is provided, wherein the electroconductive adhesive comprises the ingredient (A) of 72.5-91.0 wt.%, the ingredient (B) of 27.5-9.0 wet.% and (C) an aromatic β-ketone (such as 1,3-diphenyl-1,3-propanedione) of 0.08-1.5 wt.%, water-insoluble, solid at normal temperature and having a lower melting point than the curing temperature of the thermoset/adhesive resin. The electronic device, whose electronic element terminal electrode is electrically connected to an electrode-land of a circuit board with the cured product of the electroconductive adhesive and whose electronic element is mounted on the circuit board, is provided, and the method for producing the electronic device is provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a conductive adhesive, an electronic device, and a method for manufacturing the same, and more specifically, a conductive adhesive for mounting an electronic component such as a semiconductor chip, a chip component, or a discrete component on a circuit board, and the electronic component is conductive. The present invention relates to an electronic device mounted on a circuit board with a conductive adhesive and a method for manufacturing the same.

In recent years, in the field of electronics packaging, the development of lead-free packaging technology has been promoted in order to prevent environmental pollution. As lead-free mounting technology, there are mainly mounting technology that uses lead-free solder and mounting technology that uses a conductive adhesive. Expectations for conductive adhesives are increasing due to the merits.

In general, the conductive adhesive is obtained by uniformly dispersing conductive particles in a thermosetting resin-based binder having adhesiveness to a contacting substrate. Electronic components are usually mounted by applying a conductive adhesive to the electrode parts (electrode lands) of the circuit board, mounting the electronic components so that the terminal electrodes of the electronic components are in contact with the conductive adhesive, and then binding the binder. It is carried out by curing the thermosetting resin. Strength is developed by bonding the electrode part of the circuit board and the terminal electrode of the electronic component with a cured resin, and the distance between the conductive particles is shortened due to the shrinkage caused by the curing of the thermosetting resin, and the conductivity is developed. . Since the curing temperature of the thermosetting resin in the conductive adhesive is generally 200 ° C. or lower and lower than the bonding temperature of about 250 ° C. for lead-free solder, mounting of inexpensive electronic components with low heat resistance Can also be used. Further, since the joint portion between the electrode portion of the circuit board and the terminal electrode of the electronic component is a cured resin, it can flexibly follow heat and external stress. For this reason, compared with lead-free solder, there is an advantage that cracks are less likely to occur at the joint (Japanese Patent Laid-Open Nos. 7-258618 and 8-53659). For the above reasons, the conductive adhesive is useful as a bonding material for mounting electronic components and is practically used.

However, the conductive adhesive is inferior to lead-free solder in the reliability of the joint between the terminal electrode of a general-purpose electronic component and the electrode part of the circuit board. Base metals such as tin, tin alloys, and copper are usually used for terminal electrodes of electronic components and electrode portions of circuit boards. When the base metal terminal electrode of the electronic component and the base metal electrode portion of the circuit board are joined by the conductive adhesive, the connection resistance increases with time in an atmosphere of high temperature and high humidity. This is thought to be due to the fact that base metals used in terminal electrodes and electrode parts corrode in the presence of water. That is, since the conductive metal particles such as silver particles in the conductive adhesive and the base metal electrode such as tin are dissimilar metals, a kind of battery is introduced through the infiltrated water where they are in contact with each other. And the base metal electrode having a low potential is electrically corroded. For this reason, in order to ensure reliability in a high-temperature and high-humidity atmosphere when bonding using a conductive adhesive, gold, silver, not an inexpensive base metal terminal electrode or base metal electrode part, There is a problem that it is necessary to use expensive noble metal terminal electrodes and electrode parts such as palladium.

Japanese Patent Application Laid-Open No. 2002-161259 includes a binder resin, conductive particles, and an elution preventing film forming agent (chelating agent), and the elution preventing film forming agent is interposed via the conductive particles when the binder resin is cured. There has been proposed a conductive adhesive that reacts after the electrical continuity developed inside the conductive adhesive to form an elution preventing film on the surface of the conductive particles. An elution preventing film forming agent (chelating agent) is effective for preventing ion migration and sulfidation, and anthranilic acid (melting point: 143 ° C.≈activation temperature), pyrogallol (132 ° C.), 1-nitroso-2-naphthol (melting point: 110) ° C) is preferred. Therefore, the present inventor examined the effect of adding a water-soluble or warm water slightly soluble chelating agent such as anthranilic acid or pyrogallol to the conductive adhesive, and the conductive adhesive containing such a chelating agent is It has been found that since the connection resistance increases with time in an atmosphere of high temperature and high humidity after curing, the reliability of the connection resistance is lacking. 1-Nitroso-2-naphthol is difficult to obtain even as a reagent because it contains a nitroso group and is not a safe compound for the human body.

Japanese Patent Laid-Open No. 7-258618 JP-A-8-53659 JP 2002-161259 A

Therefore, in order to develop a conductive adhesive that can maintain the reliability of connection resistance in a high-temperature and high-humidity atmosphere even when applied to a general-purpose inexpensive base metal terminal electrode or base metal electrode part, the present inventor, In addition, earnest research to develop an electronic device that can maintain the reliability of connection resistance in a high-temperature, high-humidity atmosphere even if the base metal terminal electrode of the electronic component and the base metal electrode portion of the circuit board are joined with a conductive adhesive. As a result, the development was successful. Even when the present invention is applied to a general-purpose inexpensive base metal terminal electrode or base metal electrode part, the connection resistance hardly increases over time in a high-temperature and high-humidity atmosphere, and the reliability of the connection resistance is increased. An object is to provide a conductive adhesive that can be maintained for a period of time. In addition, even if the base metal terminal electrode of the electronic component and the base metal electrode portion of the circuit board are joined with a conductive adhesive, the connection resistance hardly increases over time in a high-temperature and high-humidity atmosphere. An object of the present invention is to provide an electronic device that can maintain reliability for a long period of time and a method for manufacturing the same.

The present invention
“[1] (A) conductive metal particles, (B) a conductive adhesive composition comprising a thermosetting / adhesive resin binder, component (A) is 72.5 wt% to 91.0 wt% Containing 27.5 wt% to 9.0 wt% of component (B), and (C) aroma that is insoluble in water, solid at room temperature, and has a melting point lower than the curing temperature of the thermosetting / adhesive resin A conductive adhesive comprising 0.08 wt% to 1.8 wt% of a group β-diketone.
[2] The conductive adhesive according to [1], wherein the aromatic β-diketone is 1,3-diphenyl-1,3-propanedione or 1-phenyl-1,3-propanedione .
[3] The conductive metal particles are silver particles, the thermosetting / adhesive resin binder is an epoxy resin, an epoxy resin curing agent, or an epoxy resin and an epoxy resin curing agent, and a reactive diluent. The conductive adhesive according to claim 1 or 2, characterized by comprising:
[4] The conductive adhesive according to [1] or [3], wherein the conductive metal particles have an average particle size of 10 μm or less.
[5] The conductive adhesive according to any one of [1] to [4], wherein the conductive adhesive is an adhesive for electrically connecting a terminal electrode of an electronic component to an electrode land of a circuit board.
[6] An electronic component wherein the terminal electrode of the electronic component is electrically connected to the electrode land of the circuit board by a cured product of the conductive adhesive according to any one of [1] to [4] An electronic device with components mounted on a circuit board.
[7] The conductive adhesive according to any one of [1] to [4] is interposed between the terminal electrode of the electronic component and the electrode land of the circuit board, and the melting point of the β-diketone in the conductive adhesive is higher than the melting point. A method of manufacturing an electronic device in which an electronic component is mounted on a circuit board, wherein the conductive adhesive is cured at a temperature to electrically connect the terminal electrode and the electrode land. ".

The conductive adhesive of the present invention is a general-purpose inexpensive base metal or a metal plated with a base metal when used for joining a terminal electrode of an electronic component and an electrode part of a circuit board. In addition, even if the electrode part of the circuit board is made of a base metal (for example, tin, tin alloy, copper) or a metal plated with a base metal, the connection resistance is little over time in a high-temperature and high-humidity atmosphere. However, the reliability of the connection resistance can be maintained for a long time. In the electronic device of the present invention, a base terminal made of a base metal or a base metal plated with a base metal of an electronic component and a base metal electrode part of a circuit board or a metal electrode plated with a base metal are joined with a conductive adhesive. However, the connection resistance hardly increases over time in a high temperature and high humidity atmosphere, and the reliability of the connection resistance can be maintained for a long time. It is not necessary to use expensive noble metals such as gold, silver, and palladium, or plating of such metals for terminal electrodes of electronic components and electrode portions of circuit boards, and manufacturing costs can be reduced. The electronic device manufacturing method of the present invention can manufacture the electronic device simply and efficiently.

The conductive adhesive of the present invention comprises (A) conductive metal particles and (B) a conductive adhesive composition comprising a thermosetting / adhesive resin-based binder, wherein the component (A) is 72.5 wt% to 91% by weight, 27.5% to 9.0% by weight of component (B), and further (C) water-insoluble, solid at room temperature, melting point is the curing temperature of the thermosetting / adhesive resin It is characterized by containing 0.08% to 1.8% by weight of a lower aromatic β-diketone. As a matter of course, the total amount of the component (A), the component (B) and the component (C) is 100% by weight.

(A) The conductive metal particles are silver, gold, copper, nickel, palladium, tin, zinc and solid metal particles that are excellent in conductivity and stability, such as alloys containing these metals as main components. preferable. The conductive metal particles may be blended singly or in combination.

The shape of these conductive metal particles is arbitrary, spherical, elliptical, spindle, disc, prismatic, prismatic, cylindrical, flake, fibrous, amorphous, and many primary particles are connected. The shape which forms the next particle is illustrated. Also, if the particle size of the conductive metal particles is too large, it becomes easy to separate from the (B) thermosetting / adhesive resin binder during storage, and the mechanical strength of the conductive adhesive cured product tends to decrease. Therefore, the maximum particle size is approximately 30 μm or less, preferably 15 μm or less, more preferably 10 μm or less, and the average particle size is preferably 0.5 to 8 μm. The lower limit is not particularly limited, and may be nanoparticles. The average particle diameter is the particle diameter when the particle size distribution is measured by a laser diffraction / scattering method and the weight accumulation reaches 50%.

(A) The content of the conductive metal particles in the conductive adhesive is 72.5 wt% to 91.0 wt%, and the conductive particles need to have conductivity, specific gravity, bulk density, and conductive adhesive. An appropriate content may be selected depending on the conductive performance.

The (B) thermosetting / adhesive resin-based binder is preferably a liquid at room temperature, and (A) the binder component of the conductive metal particles, and the action of making the conductive powder metal particles into a paste or the like There is.
The (B) thermosetting / adhesive resin-based binder is usually composed of a thermosetting / adhesive resin and its curing agent, but may contain an adhesion promoter or a reactive diluent as required.
From the viewpoints of workability, curability, adhesion to electrodes and the like, and mechanical strength after curing, a binder mainly composed of an epoxy resin is most preferable. As epoxy resins, bisphenol epoxy resins such as bisphenol F diglycidyl ether, bisphenol A diglycidyl ether, bisphenol AD diglycidyl ether; polyglycidyl ether obtained by reaction of phenol novolacs with epichlorohydrin; butanediol diglycidyl ether, Examples include aliphatic epoxy resins such as neopentyl glycol diglycidyl ether; alicyclic epoxy resins such as dicyclopentanedienemethanol diglycidyl ether; heterocyclic epoxy resins such as diglycidyl hydantoin; and modified epoxy resins. Any of them is preferably liquid at room temperature. An epoxy resin may be used independently and may mix and use 2 or more types.

It is preferable that the epoxy resin with insufficient adhesion contains an adhesion promoter. Examples of the adhesion promoter include silane coupling agents and titanium coupling agents. Its content is usually 2% by weight or less.

Thermosetting / adhesive resins other than epoxy resins include phenolic resin, polyurethane resin, phenoxy resin, thermosetting acrylic resin, unsaturated polyester resin, urea resin, melamine resin, furan resin, silicon resin, diallyl phthalate resin, etc. There is. All of them are liquid at room temperature and are easy to adhere to electrodes and the like. If the resin itself has insufficient adhesion or does not have adhesion, it contains an adhesion promoter.

The blending amount of the (B) thermosetting / adhesive resin-based binder may be an amount sufficient to make the (A) conductive metal particles into a paste. Since it varies depending on the viscosity and viscosity of the thermosetting / adhesive resin in component (B), the particle size, shape, bulk density, etc. of the conductive metal particles, it is difficult to define uniformly. 27.5 wt% to 9.0 wt% of the conductive adhesive is preferred.

(B) The curing agent in the thermosetting / adhesive resin-based binder may be a curing agent commonly used for each thermosetting / adhesive resin.
When the thermosetting / adhesive resin is an epoxy resin, the curing agent rapidly reacts with the epoxy resin upon heating (for example, about 50 to 200 ° C.) to solidify the epoxy resin and is at room temperature or lower. As long as it has long-term storage stability at a temperature of 5 ° C., it is not particularly limited. Examples of the curing agent include aliphatic polyamines, polyaminoamides, aromatic amines, alicyclic diamines, tertiary amines and other amine compounds; aliphatic aminocarboxylic acids, imidazoles, carboxylic anhydrides, phenols, phenol resins, Examples include hydrazide compounds, dicyandiamide, and Lewis acid complex compounds.

More specifically, epoxy resin curing agents include diethylenetriamine, triethylenetetramine, metaxylenediamine, dimer acid polyamide, 4,4'-diamonodiphenylmethane, metaphenylenediamine, 2,4,6-tris (diamino). Methyl) phenol, ε-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole Examples include 2-phenyl-4-methyl-5-hydroxymethylimidazole, phthalic anhydride, tetrahydromethyl phthalic anhydride, phenol novolac resin, adipic acid dihydrazide, isophthalic acid hydrazide, and boron trifluoride / ethylamine complex. These curing agents may be blended alone or in combination.

These curing agents may be those encapsulated in a capsule of a heat-meltable polymer substance or dispersed in particles of a heat-meltable substance, that is, a latent curing agent. The latent curing agent has both long-term storage properties and fast curing properties. These latent hardeners may be blended singly or in combination of a plurality of types.

When the thermosetting / adhesive resin is phenol resin, polyurethane resin, phenoxy resin, thermosetting acrylic resin, unsaturated polyester resin, urea resin, melamine resin, furan resin, silicon resin, diallyl phthalate resin, etc. The agent may be a curing agent commonly used for each resin.

(B) The content of the curing agent in the thermosetting / adhesive resin binder varies depending on the type of thermosetting / adhesive resin, the type of curing agent, the heating temperature, etc., so it is difficult to specify uniformly. Is usually 0.3 to 7% by weight, preferably 0.5 to 5% by weight.

The conductive adhesive of the present invention comprises (C) 0.08% by weight to 1.8% by weight of an aromatic β-diketone that is insoluble in water, solid at room temperature, and has a melting point lower than the curing temperature of the thermosetting / adhesive resin. It is characterized by containing by weight. The content is preferably 0.1% by weight to 1.2% by weight. If the amount is too small, the rate of change in connection resistance over time will be too high under high temperature and high humidity.

The aromatic β-diketone preferably has a phenyl group. Specific examples thereof include 1,3-diphenyl-1,3-propanedione (also referred to as dibenzoylmethane) and 1-phenyl-1,3-propanedione. (Also referred to as 1-benzoylacetone), those having a methyl group bonded to their phenyl group. 1,3-diphenyl-1,3-propanedione is solid at room temperature, has a melting point of 81 ° C., is insoluble in water, and is insoluble even in warm water. Compatibility with thermosetting / adhesive resins such as epoxy resins, especially thermosetting / adhesive aromatic resins such as aromatic epoxy resins because it has two phenyl groups in one molecule Is excellent. 1,3-diphenyl-1,3-propanedione is extremely excellent in chelating ability, and is considered to have an effect of chelating base metal ions released from electrodes and the like to make them insoluble and inactive.

1-Phenyl-1,3-propanedione is solid at room temperature, has a melting point of 61 ° C., and is insoluble in water. Since it has a phenyl group in the molecule, it has excellent compatibility with thermosetting and adhesive resins such as epoxy resins, especially with thermosetting and adhesive aromatic resins such as aromatic epoxy resins. . In addition, it is excellent in chelating ability and is thought to have the effect of chelating base metal ions released from the electrode to make them insoluble and inactive.

When the conductive adhesive containing the aromatic β-diketone is used for joining the terminal electrode of the electronic component and the electrode portion of the circuit board, the terminal electrode of the electronic component is made of a general-purpose inexpensive base metal or base metal plated Even if the circuit board electrodes are made of base metal or base metal plated, the connection resistance hardly increases over time in a high-temperature and high-humidity atmosphere. Sex can be maintained for a long time.

The conductive adhesive of the present invention may contain a reactive diluent for a thermosetting / adhesive resin. Reactive diluent reduces the viscosity of thermosetting / adhesive resin, and thus conductive adhesive, improves workability during printing and application, and has the effect of improving adhesion to the adherend. is there. Most of the reactive diluent reacts and bonds with the thermosetting / adhesive resin in the component (B) when the conductive adhesive is cured to form a cured product. Therefore, it is one component of component (B).

Preferred reactive diluents vary depending on the type of thermosetting / adhesive resin in component (B). For example, as reactive diluents for epoxy resins, butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, n-butyl glycidyl ether, p-sec-butylphenyl glycidyl Examples include ether, tert-butylphenyl glycidyl ether, tertiary carboxylic acid glycidyl ester, alkyl monoglycidyl ether, and alkylene diglycidyl ether.

The content of the reactive diluent in the conductive adhesive is not particularly limited as long as it is sufficient to optimize the viscosity and fluidity of the conductive adhesive. For example, 0 (not including 0) ) To 25% by weight, preferably 0 (not including 0) to 15% by weight.

The conductive adhesive of the present invention may contain a solvent. The solvent significantly reduces the viscosity of the thermosetting / adhesive resin, and thus the conductive adhesive, and thus has an effect of enabling thin film coating. The solvent is not a constituent component of the component (B) because all of the solvent volatilizes and evaporates when the conductive adhesive is cured.
The preferred solvent varies depending on the type of thermosetting / adhesive resin in component (B). For example, as solvents for epoxy resins, alkyl ethers of dihydric alcohols such as ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, propylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol diethyl ether; propylene glycol monomethyl ether acetate, propylene glycol Examples include ether esters of dihydric alcohols such as monoethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate; γ-butyl lactone, propylene carbonate, N-methyl-2-pyrrolidone, and benzyl alcohol.

The blending amount of the solvent in the conductive adhesive is not particularly limited as long as it is sufficient to optimize the viscosity and fluidity of the conductive adhesive. For example, 0 (not including 0) to 10 % By weight, preferably 0 (not including 0) to 5% by weight.

The conductive adhesive of the present invention preferably contains an antioxidant.
Antioxidant suppresses oxidation of conductive metal particles during storage and heat curing of conductive adhesive, and decreases adhesive strength due to oxidative decomposition of thermosetting and adhesive resins such as epoxy resins during heat curing And has the effect of reducing the decrease in conductivity. Examples of the antioxidant include a phenolic antioxidant, an organic phosphorus antioxidant, and an amine antioxidant. Specifically, 2,6-ditert-butyl-p-cresol, 2,6-ditert-butylphenol, 4,4′-butylidenebis (3-methyl-6-tert-butyl) are used as phenolic antioxidants. -m-cresol), tetrakis [methylene (3,5-di-tert-butyl-4-hydroxyhydrocinnamate)] methane, 1,3,5-tris (3,5-di-tert-butyl- Examples include 4-hydroxybenzyl-s-triazine-2,4,6- (1H, 3H, 5H) trione, and organic phosphorus antioxidants include triphenyl phosphite and trioctadecyl phosphite. Examples of the antioxidant include N-phenyl-β-naphthylamine, 2 (2′-hydroxy-5′-methylphenyl) benzotriazole, 6-ethoxy-2,4,6-trimethyl-1, 2-dihydroquinoline is exemplified.

The blending amount of the antioxidant is not particularly limited, but usually a range of 0.03 wt% to 3 wt% of the conductive adhesive is preferable.

The conductive adhesive of the present invention may contain other additives. Examples of such additives include pigments, flexibility imparting agents, thixotropic agents, fillers, and heat conductive particles. Flexibility imparting agents include thermoplastic polymers, silicone rubber fine particles, thixotropic agents include hardened castor oil, dibenzylidene sorbitols, and fillers include aluminum oxide particles, zinc oxide particles, mica powder, calcium carbonate. Examples thereof include powder, quartz powder, and silica fine powder.

The conductive adhesive of the present invention can be easily produced by uniformly mixing components (A) to (C) with other optional components as necessary. At that time, it is preferable that (C) aromatic β-diketone, which is a chelate-forming compound, is previously dissolved or heated and melted in the thermosetting / adhesive resin in component (B) and then mixed with other components.

The conductive adhesive thus obtained may be solid at room temperature, but is preferably liquid or pasty in terms of workability, and can be used for electrical parts, electrical equipment, coating, printing, dripping, casting, pouring, etc. It can be applied to places that require conductive adhesion, such as electronic parts and electronic devices. It hardens | cures by heating after application to the location which needs electroconductive adhesion. The heating temperature is a temperature equal to or higher than the melting point of component (C), and depends on the thermosetting / adhesive resin in component (B) and the type and blending ratio of (C) curing agent, the type of adherend, etc. Choose an appropriate temperature and time.

In the electronic device of the present invention, the terminal electrode of the electronic component is electrically connected to the electrode land of the circuit board by the cured product of the conductive adhesive of the present invention, that is, the electronic component is mounted on the circuit board. It is characterized by being. Electronic components such as semiconductor chips, discrete components, sensor components, electrolytic capacitors, diodes, switches, and other chip components, QFP (Quad Flat Package), CSP (Chip Size Package), BGA (Ball Grid Array), or wafer state Examples include package parts such as WLP (Wafer Level Packaging) and lead parts obtained by packaging and dicing into individual pieces.
Examples of the circuit board include a single-layer printed wiring board, a multilayer printed wiring board, and a motherboard.
As an electric / electronic device in which the electronic device of the present invention is incorporated, a cellular phone, a portable recorder, a television, a personal computer, a printer, a DVD recorder, a copying machine, a home appliance, a communication device, an inter-vehicle sensor, an engine control unit, a brake The control electronics of the system are illustrated.

In the electronic device of the present invention, the conductive adhesive of the present invention is interposed between the terminal electrode of the electronic component and the electrode land of the circuit board, and is conductive at a temperature equal to or higher than the melting point of the β-diketone in the conductive adhesive. It can be easily manufactured by curing the adhesive and electrically connecting the terminal electrode and the electrode land. Since the conductive adhesive of the present invention is mainly composed of a thermosetting / adhesive resin such as an epoxy resin, the adhesive strength is excellent, and the terminal electrode of the electronic component and the electrode land of the circuit board are strongly bonded. be able to.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but these examples do not limit the present invention.
[Solubility of chelate-forming compounds in epoxy resin]
Each chelate-forming compound powder was mixed with bisphenol F type epoxy resin (Epicoat YL983U manufactured by Japan Epoxy Resin Co., Ltd., viscosity 387 Pa · s at 25 ° C., epoxy equivalent 170 g / equivalent) at 5% by weight, and at 50 ° C. After heating for 30 minutes, the solubility in the epoxy resin was visually observed.
[Water solubility of chelate-forming compounds]
1 wt% of each chelate-forming compound powder was mixed with water and heated at 50 ° C. for 30 minutes, and the solubility in warm water was visually observed.

[Preparation of connection resistance measurement specimen A]
A conductive adhesive was printed on the electrode land 4 of the glass fiber reinforced epoxy resin substrate 1 corresponding to the 2125 jumper chip resistor 23 with a metal mask having a thickness of 100 μm. A 2125 jumper chip resistor 23 in which terminal electrodes were tin-plated was mounted on this conductive adhesive by a chip mounter. Subsequently, it put into the hot-air circulation type oven, and it heated at 160 degreeC for 30 minute (s), and hardened | cured the electroconductive adhesive agent, and produced the test body A for connection resistance measurement (refer FIG. 1, FIG. 2).

[Measurement of connection resistance]
Each specimen A produced as described above was placed in a constant temperature and humidity chamber adjusted to 85 ° C. and a relative humidity of 85%, and held for 500 hours. For each specimen A before holding for 500 hours and each specimen A after holding for 500 hours, between the two electrode lands (electrode land-conductive adhesive-2125 jumper chip resistor-conductive) The resistance (connection resistance) of the adhesive-electrode land was measured with a digital multimeter (see FIG. 1). In FIG. 1, I means current measurement, and V means voltage measurement. The connection resistance may be referred to as contact resistance.
[Change rate of connection resistance to tin plating]

The change rate of the connection resistance with respect to tin plating was calculated by the following equation.
Change rate of connection resistance (%) = (R ₅₀₀ −R ₀ ) × 100 / R ₀
[Where R ₀ : connection resistance before holding for 500 hours (mΩ), R ₅₀₀ : connection resistance after holding for 500 hours (mΩ)]
[Judgment]
Criteria based on the connection resistance change rate are as follows.
20% or less: ○ (good), 20% to 50%: Δ (slightly good), 50% or more: × (defect)

[Preparation of electrical resistivity (specific resistance) specimen]
On a plain glass fiber reinforced epoxy resin substrate, apply a conductive adhesive with a metal mask of 80 x 2 x 0.1 mm (length x width x height) and heat at 160 ° C for 30 minutes in a hot air oven Then, the conductive adhesive was prepared by curing.

[Measurement of electrical resistivity (specific resistance)]
The substrate was taken out of the hot air oven and left at room temperature of 25 ° C. for 1 hour, and then the electrical resistance value was measured for a distance of 50 mm of the cured conductive adhesive using a digital multimeter. (Specific resistance) was calculated by the following equation.
Electric resistivity (specific resistance) (Ω · cm) = (R × t × W) / L
[Wherein, R: resistance value (Ω), t: thickness of cured conductive adhesive (cm), W: width of cured conductive adhesive (cm), L: distance between electrodes (cm)]

[Measurement of adhesive strength]
The conductive adhesive 10 was printed on the electrode land 9 of the glass fiber reinforced epoxy resin substrate 6 corresponding to the 2125 chip capacitor 7 on which the terminal electrode 8 was tin-plated with a metal mask having a thickness of 100 μm. A 2125 chip capacitor 7 was mounted on the conductive adhesive 10 with a chip mounter. Subsequently, it put in the hot-air oven, and it heated at 160 degreeC for 30 minute (s), the conductive adhesive 10 was hardened, and the test body B for adhesive strength measurement was produced (refer FIG. 3, FIG. 4). With the substrate 6 fixed, a shearing force was applied perpendicularly to the side of the 2125 chip capacitor 7 at a speed of 23 mm / min as shown by the arrow in FIG. 3, and the load when the 2125 chip capacitor peeled was measured and adhered. Strength.

[Reference example]
Melting points of (D-1) 1,3-diphenyl-1,3-propanedione, (D-2) 8-hydroxyquinoline, (D-3) anthranilic acid, (D-4) pyrogallol as chelating compounds Is shown in Table 1, and the solubility in epoxy resin and the solubility in hot water are measured.

[Example 1] to [Example 2], [Comparative Example 1] to [Comparative Example 4]
The following formulation components were prepared.
(A) Conductive particles: flaky silver filler A (average particle size 2.3 μm, tap density 5.6) and flaky silver filler B (average particle size 5.8 μm, tap density 3.6)
Mixture of thermosetting / adhesive resin and chelate-forming compound: ordinary bisphenol F type epoxy resin (Epicoat YL983U manufactured by Japan Epoxy Resin Co., Ltd., viscosity 387 Pa · s at 25 ° C., epoxy equivalent 170 g / equivalent) ( Hereinafter, 95.0 parts of epoxy resin A) and 5.0 parts of the following chelate-forming compounds were mixed in a mixer to prepare a chelate-forming compound-containing epoxy resin (Example 1, Comparative Example 1, Comparison) Example 2 and Comparative Example 3).
A chelate-forming compound-containing epoxy resin prepared by mixing 97.5 parts of epoxy resin A and 2.5 parts of chelate-forming compound D-1 below in a mixer (Example 2).
Chelate-forming compounds: (D-1) 1,3-diphenyl-1,3-propanedione, (D-2) 8-hydroxyquinoline, (D-3) anthranilic acid, (D-4) pyrogallol
(C) Curing agent: Imidazole derivative (manufactured by Shikoku Kasei Co., Ltd., phenyl group-containing type)
Reactive diluent: p-sec-butylphenylglycidyl ether

Each of the above ingredients was kneaded with a three-roll mixer at the content (% by weight) shown in Table 2 to prepare a paste-like thermosetting conductive adhesive. Using the obtained conductive adhesive, a test body A for measuring connection resistance and adhesive strength was prepared, and its characteristic values were measured and shown in Table 2.

From Table 2, the conductive adhesive of Comparative Example 4 that does not contain a chelate-forming compound, and a comparison that contains a chelate-forming compound that is insufficiently soluble in epoxy resin or that is soluble in water The conductive adhesive of Example 1, the conductive adhesive of Comparative Example 2, and the conductive adhesive of Comparative Example 3 all have a remarkably large connection resistance change rate, but are soluble in epoxy resin and are insoluble in hot water. It can be seen that the conductive adhesive of Example 1 and the conductive adhesive of Example 2 containing 1,3-diphenyl-1,3-propanedione are excellent in that the connection resistance change rate is small.

[Example 3] to [Example 7], [Comparative Example 5] to [Comparative Example 6]
The following formulation components were prepared.
(A) Conductive particles: flaky silver filler A (average particle size 2.3 μm, tap density 5.6) and flaky silver filler B (average particle size 5.8 μm, tap density 3.6)
Thermosetting / adhesive resin: normal bisphenol F type epoxy resin (epoxy resin A)
Mixture of thermosetting / adhesive resin and chelate-forming compound: from 95.0 parts of ordinary bisphenol F type epoxy resin (epoxy resin A) and 5.0 parts of 1,3-diphenyl-1,3-propanedione A modified bisphenol F type epoxy resin (hereinafter referred to as a modified epoxy resin B).
(C) Curing agent: Imidazole derivative (manufactured by Shikoku Kasei Co., Ltd., phenyl group-containing type)
Reactive diluent: tertiary carboxylic acid glycidyl ester;
The above ingredients were kneaded with a three-roll mixer at the content (% by weight) shown in Table 3 to prepare a paste-like and thermosetting conductive adhesive. Various characteristics of the obtained conductive adhesive were measured and shown in Table 3.

From Table 3, the conductive adhesives of Examples 3 to 7 in which the content of 1,3-diphenyl-1,3-propanedione in the conductive adhesive is 0.65 to 0.13% by weight are as follows. Although the connection resistance change rate is small and good, the conductive adhesive of Comparative Example 5 having a 1,3-diphenyl-1,3-propanedione content of 0% by weight has a remarkably large connection resistance change rate. It can be seen that the conductive adhesive of Comparative Example 6 having a 1,3-diphenyl-1,3-propanedione content of 0.05% by weight has a considerably high connection resistance change rate.

[Example 8] to [Example 11], [Comparative Example 7] to [Comparative Example 8]
In Example 1 and Example 2, a mixture of ordinary bisphenol F type (epoxy resin A) and modified epoxy resin B in a ratio of 1: 1 was used, and tertiary glyceric acid glycy was used as a reactive diluent. Except for the use of the gil ester, the same compounding ingredients were used, and the content (% by weight) shown in Table 4 was kneaded with a three-roll mixer to form a paste-like thermosetting conductive adhesive. An agent was prepared. Various characteristics of the obtained conductive adhesive were measured and shown in Table 4.

According to Table 4, the content of 1,3-diphenyl-1,3-propanedione is 0.53 to 0.13% by weight, and the content of the flaky silver filler is 75% to 90% by weight. The conductive adhesives of Examples 8 to 11 have good small change in connection resistance, but the conductive adhesive of Comparative Example 7 in which the content of flaky silver filler is 70% by weight is low in connection resistance. It can be seen that the conductive adhesive of Comparative Example 8 having a remarkably large electrical resistivity (specific resistance) and a flaky silver filler content of 92% by weight has a remarkably low adhesive strength.

The connection resistance measurement test body A of the example is also an example of the electronic device of the present invention.
The test body A for measuring connection resistance includes a glass fiber reinforced epoxy resin substrate 1 and a 2125 jumper chip resistor 23 mounted thereon and electrically connected and fixed by a conductive adhesive. The 2125 jumper chip resistor 23 includes a zero resistance chip 2 and a terminal electrode 3 bonded to both ends thereof. The terminal electrode 3 is tin-plated. Each terminal electrode 3 is located on each electrode land 4 of the glass fiber reinforced epoxy resin substrate 1, and there is a cured conductive adhesive layer 5 between each terminal electrode 3 and each electrode land 4. 3 and each electrode land 4 are electrically connected and are firmly bonded.

The conductive adhesive of the present invention includes semiconductor components, discrete components, sensor components, electrolytic capacitors, diodes, switches and other chip components, QFP (Quad Flat Package), CSP (Chip Size Package), BGA (Ball Grid Array). Also useful for mounting electronic parts such as package parts such as WLP (Wafer Level Packaging) such as real chip size obtained by packaging and dicing into pieces in the wafer state, and lead parts. It is useful for electrically connecting the terminal electrode of the electronic component to the electrode land of the circuit board.
An electronic device in which the electronic component of the present invention is mounted on a circuit board includes a cellular phone, a portable recorder, a television, a personal computer, a printer, a DVD recorder, a copying machine, a home appliance, a communication device, as an electric / electronic device. It is useful for inter-vehicle sensors, engine control units, control electronics for brake systems, etc.
The method for manufacturing an electronic device in which the electronic component of the present invention is mounted on a circuit board is useful for efficiently manufacturing the electronic device.

It is a top view of the test body A for connection resistance measurement. FIG. 2 is a cross-sectional view taken along line Y-Y ′ of the test body A for connection resistance measurement in FIG. 1. It is a top view of the test body B for adhesive strength measurement. FIG. 4 is a cross-sectional view taken along line Y-Y ′ of the test body B for measuring adhesive strength in FIG. 3.

Explanation of symbols

A Test specimen for measuring connection resistance B Test specimen for measuring adhesive strength 1 Glass fiber reinforced epoxy resin substrate 2 Zero resistance chip 3 Terminal electrode 23 2125 jumper chip resistor 4 Electrode land 5 Conductive adhesive 6 Glass fiber reinforced epoxy resin substrate 7 Chip capacitor 8 Chip capacitor terminal electrode 9 Electrode land 10 Conductive adhesive

Claims (7)

In the conductive adhesive composition comprising (A) conductive metal particles and (B) a thermosetting / adhesive resin-based binder, the component (A) is contained in an amount of 72.5 wt% to 91.0 wt%. Aromatic β-diketone containing 27.5% to 9.0% by weight of (B), (C) water-insoluble, solid at room temperature, and having a melting point lower than the curing temperature of the thermosetting / adhesive resin Containing 0.08 wt% to 1.8 wt% of a conductive adhesive. The conductive adhesive according to claim 1, wherein the aromatic β-diketone is 1,3-diphenyl-1,3-propanedione or 1-phenyl-1,3-propanedione. The conductive metal particles are silver particles, and the thermosetting / adhesive resin binder comprises an epoxy resin and an epoxy resin curing agent, or an epoxy resin and an epoxy resin curing agent, and a reactive diluent. The conductive adhesive according to claim 1 or 2, characterized by the above. The conductive adhesive according to claim 1 or 3, wherein the conductive metal particles have an average particle size of 10 µm or less. The conductive adhesive according to any one of claims 1 to 4, wherein the conductive adhesive is an adhesive for electrically connecting a terminal electrode of an electronic component to an electrode land of a circuit board. The terminal electrode of an electronic component is electrically connected to the electrode land of a circuit board by the hardened | cured material of the conductive adhesive of any one of Claims 1-4, The electronic component characterized by the above-mentioned Is an electronic device mounted on a circuit board. The conductive adhesive according to any one of claims 1 to 4 is interposed between a terminal electrode of an electronic component and an electrode land of a circuit board, and a temperature equal to or higher than the melting point of the β-diketone in the conductive adhesive. A method of manufacturing an electronic device in which an electronic component is mounted on a circuit board, wherein the conductive adhesive is cured to electrically connect the terminal electrode and the electrode land.

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