HK1155194B - Anisotropic conductive adhesive - Google Patents

Description

Anisotropic conductive adhesive

Technical Field

The present invention relates to an anisotropic conductive adhesive.

Background

As a method of mounting chip components such as driver ICs and LED elements on a circuit board, a flip-chip mounting method using an anisotropic conductive film formed into a film shape by dispersing conductive particles in an epoxy adhesive is widely used (patent document 1). The method realizes the electrical connection between the chip component and the circuit substrate through the conductive particles in the anisotropic conductive film, and realizes the fixation of the chip component on the circuit substrate through the epoxy adhesive, so the connection process is short, and the high production efficiency can be realized.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 3342703

Disclosure of Invention

However, when a chip component is mounted on a circuit board by using an anisotropic conductive film of an epoxy adhesive and reliability tests such as a reflow test, a thermal shock test (TCT), a high temperature and high humidity test, and a Pressure Cooker Test (PCT) are performed on the obtained assembly, the following problems are more likely to occur: generating an internal stress based on a difference in thermal expansion coefficient between the circuit substrate and the chip, and increasing an on-resistance value between the chip and the circuit substrate; and the chip parts are peeled off from the circuit substrate. These problems are no exception in LED devices that have recently received attention as energy-saving lighting materials.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a circuit board and a chip component which can maintain high conduction reliability between the circuit board and the chip component and can maintain good adhesion between them and a cured anisotropic conductive adhesive even when a reliability test involving heating of an assembly such as a reflow test, a thermal shock test (TCT), a high temperature and high humidity test, and a Pressure Cooker Test (PCT) for a chip component mounted on the circuit board using the anisotropic conductive adhesive is performed.

The present inventors have attempted to reduce the elastic modulus of a cured product of an anisotropic conductive adhesive in order to relax internal stress generated in a circuit board, a chip component, and a cured product of an anisotropic conductive adhesive, respectively, when performing a reliability test with heating such as a reflow test, and as a result, have found that simply reducing the elastic modulus is effective for relaxing the internal stress, but has a problem of a significant reduction in conduction reliability. Under the above circumstances, it has been unexpectedly found that the elastic modulus is plotted against temperature, and the elastic modulus distribution of the obtained curve has a close relationship with the reliability evaluation result of the anisotropic conductive adhesive, and the relationship falls into several relational expressions, thereby completing the present invention.

That is, the present invention is an anisotropic conductive adhesive comprising an epoxy adhesive containing an epoxy compound and a curing agent and conductive particles dispersed therein, wherein the cured product thereof has an elastic modulus EM at 35 ℃, 55 ℃, 95 ℃ and 150 ℃ respectively³⁵、EM⁵⁵、EM⁹⁵And EM¹⁵⁰The rate of change of the modulus of elasticity between 55 ℃ and 95 ℃ is Δ EM^55-95The rate of change of the modulus of elasticity between 95 ℃ and 150 ℃ is Δ EM^95-150When the above-mentioned compounds are used, the following expressions (1) to (5) are satisfied. Here, the elastic modulus change rate Δ EM^55-95And Δ EM^95-150Specifically, the following numerical expressions (6) and (7) are defined, respectively.

The modulus of elasticity in the present invention is a value measured in accordance with JIS K7244-4. Specifically, the measurement was carried out in a tensile mode at a frequency of 11Hz and a temperature rise rate of 5 ℃ per minute using a dynamic viscoelasticity measuring apparatus (for example, DDV-01FP-W, エ - アンドデ).

700MPa≤EM³⁵≤3000MPa (1)

EM¹⁵⁰＜EM⁹⁵＜EM⁵⁵＜EM³⁵ (2)

ΔEM^55-95＜ΔEM^95-150 (3)

20％≤ΔEM^55-95 (4)

40％≤ΔEM^95-150 (5)

ΔEM^55-95(％)＝{(EM⁵⁵-EM⁹⁵)/EM⁵⁵}×100(6)

ΔEM^95-150(％)＝{(EM⁹⁵-EM¹⁵⁰)/EM⁹⁵}×100(7)

The present invention also provides a connection structure obtained by flip-chip mounting a chip component on a circuit board using the anisotropic conductive adhesive. The elastic modulus of the cured product of the anisotropic conductive adhesive of the present invention satisfies formulas (1) to (5). Therefore, even when an assembly obtained by assembling chip components on a circuit board using the anisotropic conductive adhesive of the present invention is subjected to a reliability test involving heating of the assembly, such as a reflow test for lead-free solder, a thermal shock test (TCT), a high temperature and high humidity test, and a Pressure Cooker Test (PCT), high conduction reliability between the circuit board and the chip components can be maintained, and the adhesion between the circuit board and the cured anisotropic conductive adhesive can be maintained in a good state.

Brief Description of Drawings

FIG. 1 shows the elastic modulus distribution curve of the cured product of the anisotropic conductive adhesive of the present invention with respect to temperature.

Fig. 2 shows the elastic modulus distribution curve of a cured product of a conventional anisotropic conductive adhesive with respect to temperature.

Modes for carrying out the invention

The anisotropic conductive adhesive of the present invention is an adhesive in which conductive particles are dispersed in an epoxy adhesive containing an epoxy compound and a curing agent, and the elastic modulus of the cured product thereof is EM at 35 ℃, 55 ℃, 95 ℃ and 150 ℃, respectively³⁵、EM⁵⁵、EM⁹⁵And EM¹⁵⁰The rate of change of the modulus of elasticity between 55 ℃ and 95 ℃ is Δ EM^55-95The rate of change of the modulus of elasticity between 95 ℃ and 150 ℃ is Δ EM^95-150When the above-mentioned numerical expressions (1) to (5) are satisfied.

An example of the elastic modulus distribution satisfying these equations (1) to (5) is shown in fig. 1 (the vertical axis represents the elastic modulus, and the horizontal axis represents the temperature). Fig. 2 shows an example of the distribution of the elastic modulus of the conventional anisotropic conductive adhesive. The conventional anisotropic conductive adhesive of fig. 2 does not contain a predetermined polymer compound, and therefore, even if the temperature is raised to some extent, the elastic modulus is hard to change, but when the temperature exceeds a certain temperature, the elastic modulus tends to sharply decrease due to exceeding the glass transition temperature.

The following detailed description specifies the meanings of the above numerical formulas (1) to (5) of the anisotropic conductive adhesive of the present invention.

The formula (1) represents that the elastic modulus of the cured product of the anisotropic conductive adhesive at 35 ℃ is in the range of 700MPa to 3000 MPa. Here, the reason for using the temperature "35 ℃" is that: in general, the change in the elastic modulus of an epoxy resin cured product is negligible and relatively small at a temperature lower than 35 ℃, and therefore, it is significant to use 35 ℃ as a reference temperature. In addition, the elastic modulus EM at 35 deg.C³⁵When the pressure is less than 700Mpa, the initial conduction reliability is problematic, and when the pressure exceeds 3000Mpa, the tendency to cause the conduction reliability after the moisture absorption reflow test is increased.

The formula (2) shows that the elastic modulus of the cured product of the anisotropic conductive adhesive decreases with the temperature of 35 ℃, 55 ℃, 95 ℃ and 150 ℃. When the elastic modulus does not decrease with an increase in temperature, the internal stress of the pressure-sensitive adhesive (cured product) increases due to an increase in temperature, and as a result, the problems such as a decrease in adhesive strength and a decrease in conduction reliability tend to occur. Here, the temperature of 150 ℃ has the following meaning: corresponds to the temperature at which the LED device emits light, and is the temperature at which the anisotropic conductive adhesive is heated at the time of reflow soldering. The reason for measuring the elastic modulus at two points of 55 ℃ and 95 ℃ between 35 ℃ and 150 ℃ is that: focusing on the relationship between the effect of the present invention and the reduction rate of the elastic modulus, it is found that the use of the elastic modulus values measured at two points of 55 ℃ and 95 ℃ is appropriate in the experiment.

The formula (3) represents the rate of change of elastic modulus Δ EM between 95 ℃ and 150 ℃^95-150A rate of change of elastic modulus Δ EM between greater than 55 ℃ and 95 ℃^55-95. When the two are equal, the internal stress relaxation is insufficient, and if the relationship is reversed, the tendency that the conduction reliability cannot be maintained increases.

The formula (4) represents the rate of change of elastic modulus DeltaEM between 55 ℃ and 95 ℃^55-95Is more than 20 percent. If the ratio is less than 20%, the on reliability tends to be lowered. The formula (5) represents the rate of change of elastic modulus DeltaEM between 95 ℃ and 150 ℃^95-150Is more than 40%. If the ratio is less than 40%, the on reliability tends to be low. Note that, Δ EM^55-95And Δ EM^95-150The preferable ranges of (5 ') and (4') below.

20％≤ΔEM^55-95≤35％ (4′)

40％≤ΔEM^95-150≤70％ (5′)

Next, specific components of the anisotropic conductive adhesive of the present invention having the above-described elastic modulus characteristics of the cured product will be described. As described above, the anisotropic conductive adhesive of the present invention is an adhesive in which conductive particles are dispersed in an epoxy adhesive containing an epoxy compound and a curing agent.

The epoxy compound is preferably a compound or resin having 2 or more epoxy groups in the molecule. These may be in the form of a liquid or a solid. The method specifically comprises the following steps: glycidyl ethers obtained by reacting epichlorohydrin with polyhydric phenols such as bisphenol a, bisphenol F, bisphenol S, hexahydrobisphenol a, tetramethylbisphenol a, diarylbisphenol a, hydroquinone, catechol, resorcinol, cresol, tetrabromobisphenol a, trihydroxybiphenyl, benzophenone, bisresorcinol, bisphenol hexafluoroacetone, tetramethylbisphenol a, tetramethylbisphenol F, tris (hydroxyphenyl) methane, bisxylenol, novolak, cresol novolak and the like; polyglycidyl ethers obtained by reacting epichlorohydrin with an aliphatic polyhydric alcohol such as glycerin, neopentyl glycol, ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, polyethylene glycol, or polypropylene glycol; glycidyl ether esters obtained by reacting epichlorohydrin with hydroxycarboxylic acids such as p-hydroxybenzoic acid and β -hydroxynaphthoic acid; polyglycidyl esters obtained from polycarboxylic acids such as phthalic acid, methylphthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, endomethylenetetrahydrophthalic acid, endomethylenehexahydrophthalic acid, trimellitic acid, and polymerized fatty acids; glycidyl amino glycidyl ethers derived from aminophenols, aminoalkylphenols; glycidyl amino glycidyl esters derived from aminobenzoic acid; glycidylamines obtained from aniline, toluidine, tribromoaniline, xylylenediamine, diaminocyclohexane, bisaminomethylcyclohexane, 4 '-diaminodiphenylmethane, 4' -diaminodiphenylsulfone, or the like; known epoxy resins such as epoxidized polyolefins.

Among them, alicyclic epoxy compounds which can secure light transmittance suitable for mounting an LED element or the like on a cured product can be preferably used. The method specifically comprises the following steps: glycidyl bisphenol a hydride (glycidyl hexahydrobisphenol a), 3, 4-epoxycyclohexenylmethyl-3 ', 4' -epoxycyclohexene carboxylate, tris (2, 3-epoxypropyl) isocyanurate (TEPIC).

The curing agent may be any known curing agent for epoxy compounds and may have a latent property. For example, an acid anhydride-based curing agent, an amine-based curing agent, an imidazole-based curing agent, and the like can be used. Among these, alicyclic acid anhydride-based curing agents that can secure light transmittance suitable for LED element assembly of cured products and the like can be preferably used. Specifically, methylhexahydrophthalic anhydride may be mentioned.

The epoxy compound and the curing agent in the epoxy adhesive are used in the following amounts: when the curing agent is too small, the uncured epoxy compound component tends to be large, whereas when the curing agent is too large, the adherend tends to be corroded by the influence of the remaining curing agent, and therefore, the curing agent is used in an amount of preferably 80 to 120 parts by mass, more preferably 95 to 105 parts by mass, based on 100 parts by mass of the epoxy compound.

In the present invention, the epoxy adhesive preferably contains a polymer compound in addition to the epoxy compound and the curing agent in order to relax the internal stress. Since the weight average molecular weight is too small or too large and the internal stress relaxation effect is small, the polymer compound is preferably 5000-. In addition, since the internal stress relaxation effect is reduced when the glass transition temperature is too high, it is preferable to use a polymer compound having a glass transition temperature of 50 ℃ or less, more preferably-30 to 10 ℃.

Specific examples of the polymer compound include acrylic resins, rubbers (NBR, SBR, NR, SIS, or hydrides thereof), olefin resins, and the like. These polymer compounds preferably have a functional group such as a glycidyl group or an amino group. From the viewpoint of exhibiting good heat resistance, an acrylic resin is a preferable polymer compound. Specific examples of the acrylic resin include: a resin obtained by copolymerizing 10 to 100 parts by mass, preferably 10 to 40 parts by mass of glycidyl methacrylate or diethylaminoethyl acrylate with 100 parts by mass of ethyl acrylate.

Since the internal stress relaxation effect is reduced when the amount of the polymer compound used in the epoxy adhesive is too small, and conduction reliability tends not to be maintained when the amount is too large, it is preferably 10 to 50 parts by mass, more preferably 10 to 30 parts by mass, based on 100 parts by mass of the total of the epoxy compound, the curing agent, and the polymer compound.

An imidazole compound may be further added as a curing accelerator to the epoxy adhesive as required. Specific examples of the imidazole compound include 2-methyl-4-ethylimidazole. When the amount of the imidazole compound used is too small, the uncured component tends to be increased, and when it is too large, the adherend material tends to be corroded due to the influence of the excess curing accelerator, and therefore, it is preferably 0.01 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the curing agent.

As the conductive particles constituting the epoxy-based adhesive, conductive particles conventionally used in anisotropic conductive adhesives can be used. For example, metal particles of gold, nickel, solder, or the like, metal-plated particles of resin particles, particles on which an insulating film is coated, or the like can be used as appropriate. The particle diameter of the conductive particles is usually 3 to 10 μm as in the case of conventional conductive particles. In order to ensure good anisotropic conductivity and conduction reliability, the conductive particles are used in an amount of preferably 1 to 100 parts by mass, more preferably 10 to 50 parts by mass, based on 100 parts by mass of the epoxy adhesive.

The anisotropic conductive adhesive of the present invention may contain various additives used in conventional anisotropic conductive adhesives, as needed. For example, a silane coupling agent, a filler, an ultraviolet absorber, an antioxidant, and the like may be blended.

The anisotropic conductive adhesive of the present invention can be prepared by uniformly dispersing conductive particles in an epoxy adhesive according to a conventional method. In this case, the composition can be processed into a paste, a film, a highly viscous liquid, or the like by a conventional method. The anisotropic conductive adhesive is heat curable and can be cured by heating to 150-250 ℃.

The anisotropic conductive adhesive of the present invention can be preferably used for connecting a chip component or various modules to a circuit board. In particular, in a connection structure obtained by flip-chip mounting chip components such as an IC chip and an LED element on a circuit board using the anisotropic conductive adhesive of the present invention, even when a reliability test involving heating of an assembly such as a reflow test, a thermal shock test (TCT), a high temperature and high humidity test, or a Pressure Cooker Test (PCT) corresponding to a lead-free solder is performed, high conduction reliability is maintained between the circuit board and the chip components, and adhesion between the circuit board and the cured anisotropic conductive adhesive is maintained in a good state.

Examples

The present invention will be described more specifically with reference to examples.

Reference example 1 (preparation of acrylic resin A)

100g of Ethyl Acrylate (EA), 10g of Glycidyl Methacrylate (GMA), 0.2g of azobisbutyronitrile, 300g of ethyl acetate and 5g of acetone were put in a four-necked flask equipped with a stirrer and a condenser, and polymerization was carried out at 70 ℃ for 8 hours while stirring. The precipitated particles were collected by filtration, washed with ethanol, and dried to obtain an acrylic resin A. The weight average molecular weight of the obtained acrylic resin A was 80000, and the glass transition temperature was-40 ℃.

Reference example 2 (preparation of acrylic resin B)

100g of Ethyl Acrylate (EA), 10g of dimethylaminoethyl acrylate (DMAEA), 0.2g of azobisbutyronitrile, 300g of ethyl acetate and 5g of acetone were put into a four-necked flask equipped with a stirrer and a condenser, and polymerization was carried out at 70 ℃ for 8 hours while stirring. The precipitated particles were collected by filtration, washed with ethanol, and dried to obtain an acrylic resin B. The weight average molecular weight of the obtained acrylic resin B was 80000, and the glass transition temperature was 18 ℃.

Examples 1 to 4 and comparative examples 1 to 5

The compounding ingredients shown in table 1 were uniformly mixed with a planetary mixer to prepare an anisotropic conductive adhesive.

Evaluation test

The paste-like anisotropic conductive adhesives obtained in examples 1 to 4 and comparative examples 1 to 5 were measured for adhesive force, elastic modulus, and conduction reliability as described below.

< adhesion test >

A glass epoxy circuit board having a Cu wiring portion subjected to Au flash plating was coated with a paste-like anisotropic conductive adhesive to a thickness of 25 μm (dry thickness), and a 1.5mm square IC chip was mounted thereon, and heated at 180 ℃ for 30 seconds by a flip chip bonding machine to be hot-pressed, thereby obtaining a connection structure. The adhesive strength (N/chip) of the IC chip of the connection structure after leaving for 100 hours was measured using a die shear tester (adhesive force tester PTR1100, レスカ) immediately after obtaining (initial stage), after reflow (260 ℃) and at 150 ℃. The results obtained are shown in table 1. On the premise of the conditions of the adhesion test, it is desirable that the adhesion is 50M or more for practical use.

< measurement of elastic modulus >

An anisotropic conductive adhesive was coated on the release-treated PET so as to have a dry thickness of 80 μm, and cured by being put in an oven at 150 ℃. The cured product was peeled from the peeled PET sheet, and cut into a rectangular shape having a length of 3.5cm and a width of 0.4cm to prepare a sample. The Elastic Modulus (EM) of the sample at 35 ℃, 55 ℃, 95 ℃ and 150 ℃ was measured using a dynamic viscoelastometer (DDV-01FP-W, エ - アンドデ Co.: tensile mode, frequency 11Hz, rate of temperature rise 5 ℃/min)³⁵，EM⁵⁵、EM⁹⁵、EM¹⁵⁰). From the results obtained, the elastic modulus change rate (. DELTA.EM) was calculated from the expressions (6) and (7)^55-95、ΔEM^95-150). The results obtained are shown in table 1.

< conduction reliability test >

A paste-like anisotropic conductive adhesive was applied to a glass epoxy circuit board in which Au flash plating was applied to a Cu wiring portion to a thickness of 25 μm (dry thickness), and a 6.3mm square IC chip was mounted thereon, and then heated at 180 ℃ for 30 seconds by a flip chip bonding machine to perform hot pressing. The on-resistance of the connection structure obtained immediately after the measurement was measured by a four-terminal method. Then, the connection structure was subjected to a moisture absorption reflow test of 4-stage (moisture absorption conditions: standing at 30 ℃ C. and 60% RH for 96 hours, reflow peak temperature: 260 ℃ C.) or a moisture absorption reflow test of 2-stage (moisture absorption conditions: standing at 85 ℃ C. and 60% RH for 168 hours, reflow peak temperature: 260 ℃ C.) to measure the on-resistance. After the measurement, the connection structure was subjected to a thermal shock test (TCT: -55 ℃, 0.5 hour ← → 125 ℃, 0.5 hour, 500 cycles), and the on-resistance was measured again. When the on-resistance value is less than 1 Ω, the evaluation is good (G), and when the on-resistance value is 1 Ω or more, the evaluation is bad (NG). The results obtained are shown in table 1.

[ Table 1]

^*1 glycidyl hexahydrobisphenol A (YX8000, JER Co.)

^*Reference example 1

^*3 reference example 2

^*4 weight average molecular weight 3700, glass transition temperature 70 deg.C (YP70, Dongdu chemical Co., Ltd.)

^*5 methylhexahydrophthalic anhydride

^*62-Ethyl-4-methylimidazole (four nations chemical Co., Ltd.)

^*7 particles obtained by Ni/Au plating on the surface of crosslinked polystyrene particles having a diameter of 5 μm

As is apparent from table 1, the anisotropic conductive adhesives of examples 1 to 5 having elastic moduli satisfying the following numerical expressions (1) to (5) showed good results in terms of adhesive force in the initial stage, after reflow, and after 100 hours at 150 ℃. The conduction reliability showed good results also at the initial stage, after the moisture absorption reflow of level 4, after the moisture absorption reflow of level 2, and after 500 cycles of thermal shock.

700Mpa≤EM³⁵≤3000MPa (1)

EM¹⁵⁰＜EM⁹⁵＜EM⁵⁵＜EM³⁵ (2)

ΔEM^55-95＜ΔEM^95-150 (3)

20％≤ΔEM^55-95 (4)

40％≤ΔEM^95-150 (5)

In contrast, in comparative example 1, EM³⁵If the pressure exceeds 3000Mpa, the formula (1) is not satisfied, and the formulas (3) to (5) are not satisfied, and therefore, the required conduction reliability is not achieved even after the moisture absorption reflow test under severer conditions, not only the adhesive force but also the conduction reliability.

In comparative example 2, EM³⁵Below 700Mpa, the formula (1) is not satisfied, and therefore, the adhesive force does not obtain the desired characteristics after being left at 150 ℃ for 100 hours, and the conduction reliability does not obtain the desired characteristics immediately after the connection structure is produced.

In comparative example 3, the rate of change in elastic modulus Δ EM^55-95Less than 20%, formula (4) is not satisfied, and thus the adhesive force does not obtain desired characteristics after reflow and after standing at 150 ℃ for 100 hours. As for the conduction reliability, the required conduction reliability could not be achieved after the moisture absorption reflow test under the severer condition.

In comparative example 4, the rate of change in elastic modulus Δ EM^55-95Less than 20%, Δ EM^95-150Also less than 40%, the formulas (4) and (5) are not satisfied, and thus the adhesive force does not obtain desired characteristics after reflow and after standing at 150 ℃ for 100 hours. With respect to conduction reliability, inAfter the moisture absorption reflow test under severer conditions, the required conduction reliability cannot be achieved.

In comparative example 5, the rate of change in elastic modulus Δ EM^95-150Below 40, formula (5) is not satisfied, and therefore, the adhesive force does not obtain desired characteristics after reflow and after standing at 150 ℃ for 100 hours. As for the conduction reliability, the required conduction reliability could not be achieved after the moisture absorption reflow test under the severer condition.

Industrial applicability

The elastic modulus of the cured product of the anisotropic conductive adhesive of the present invention satisfies formulas (1) to (5). Therefore, even when a reliability test involving heating of the assembly, such as a reflow test for a lead-free solder, a thermal shock test (TCT), a high temperature and humidity test, and a Pressure Cooker Test (PCT), is performed on the assembly obtained by assembling chip components on a circuit board using the anisotropic conductive adhesive of the present invention, high conduction reliability between the circuit board and the chip components can be maintained, and the adhesion between the circuit board and the cured anisotropic conductive adhesive can be maintained in a good state. Therefore, the anisotropic conductive adhesive of the present invention is useful for connection between a circuit board and various electronic components such as chip components, modules, and flexible circuit boards.

Claims (1)

1. An anisotropic conductive adhesive comprising an epoxy adhesive containing an acrylic resin, an epoxy compound and an alicyclic acid anhydride curing agent as a curing agent, and conductive particles dispersed therein,

the acrylic resin is obtained by copolymerizing 10 to 100 parts by mass of glycidyl methacrylate or diethylaminoethyl acrylate with 100 parts by mass of ethyl acrylate, has a weight average molecular weight of 5000-,

the cured product of the anisotropic conductive adhesive is at 35 deg.C and 55 deg.CThe elastic moduli at 95 ℃ and 150 ℃ are EM, respectively³⁵、EM⁵⁵、EM⁹⁵And EM¹⁵⁰The rate of change of the modulus of elasticity between 55 ℃ and 95 ℃ is Δ EM^55-95The rate of change of the modulus of elasticity between 95 ℃ and 150 ℃ is Δ EM^95-150When the elastic modulus change rate EM satisfies the following expressions (1) to (5)^55-95And EM^95-150Defined by the following numerical formulae (6) and (7), respectively, the modulus of elasticity is a value measured in accordance with JIS K7244-4,

the epoxy adhesive contains 80 to 120 parts by mass of a curing agent per 100 parts by mass of an epoxy compound,

the amount of the acrylic resin used in the epoxy adhesive is 10 to 50 parts by mass based on 100 parts by mass of the total of the epoxy compound, the curing agent and the acrylic resin.

2. The anisotropic-electroconductive adhesive of claim 1, wherein the elastic modulus change rate Δ EM^55-95And Δ EM^95-150Satisfy the formulas (4 ') and (5'), respectively,

。

3. the anisotropic conductive adhesive of claim 1, wherein the epoxy compound is an alicyclic epoxy compound.

4. The anisotropic conductive adhesive of claim 3, wherein the alicyclic epoxy compound is a hydride of glycidyl bisphenol A or 3, 4-epoxycyclohexenylmethyl-3 ', 4' -epoxycyclohexene carboxylate, and the alicyclic acid anhydride-based curing agent is methylhexahydrophthalic anhydride.

5. The anisotropic conductive adhesive of any of claims 1 to 4, further comprising 0.01 to 10 parts by mass of 2-methyl-4-ethylimidazole as a curing accelerator with respect to 100 parts by mass of a curing agent.

6. An anisotropic conductive adhesive comprising an epoxy adhesive containing an acrylic resin, an epoxy compound and a curing agent, and conductive particles dispersed therein,

the acrylic resin is obtained by copolymerizing 10 to 100 parts by mass of diethylaminoethyl acrylate and 100 parts by mass of ethyl acrylate, has a weight average molecular weight of 5000-,

the elastic modulus of the cured product of the anisotropic conductive adhesive at 35 ℃, 55 ℃, 95 ℃ and 150 ℃ is EM³⁵、EM⁵⁵、EM⁹⁵And EM¹⁵⁰The rate of change of the modulus of elasticity between 55 ℃ and 95 ℃ is Δ EM^55-95The rate of change of the modulus of elasticity between 95 ℃ and 150 ℃ is Δ EM^95-150When the elastic modulus change rate EM satisfies the following expressions (1) to (5)^55-95And EM^95-150Defined by the following numerical formulae (6) and (7), respectively, the modulus of elasticity is a value measured in accordance with JIS K7244-4,

the epoxy adhesive contains 80 to 120 parts by mass of a curing agent per 100 parts by mass of an epoxy compound,

the amount of the acrylic resin used in the epoxy adhesive is 10 to 50 parts by mass based on 100 parts by mass of the total of the epoxy compound, the curing agent and the acrylic resin.

7. A connection structure body obtained by flip-chip assembling a chip component on a circuit substrate using the anisotropic-electroconductive adhesive according to any one of claims 1 to 6.

8. The connection structure of claim 7, wherein the chip part is an LED element.