CN100509981C - Adhesive for circuit connection - Google Patents

Abstract

The invention provides an adhesive for circuit connection. It is a heat-adhesive adhesive that heats and presses the electrodes of the opposite circuit to achieve electrical connection between the electrodes in the direction of pressure. The above-mentioned adhesive contains a thermosetting reactive resin, measured by DSC The lowest starting temperature of the exothermic reaction is 60°C, and the highest end temperature of 80% of the curing reaction is 260°C, and the calorific value until 80% of the curing reaction ends is 50-140 joules/gram.

Description

Adhesives for circuit connections

technical field

The present invention relates to an adhesive for circuit connection used between circuit boards or between electronic components such as IC chips and a wiring board.

Background technique

When performing circuit connection between circuit boards or between electronic components such as IC chips and circuit boards, anisotropic conductive adhesives in which adhesives or conductive particles are dispersed are used. That is, these adhesives can be applied between two opposing electrodes, heated and pressurized to connect the electrodes, and then electrically connected by making them conductive in the direction of pressurization. For example, Japanese Patent Laid-Open Publication No. Hei 3-16147 proposes an adhesive for circuit connection using an epoxy resin as a main component.

However, with epoxy resin as the main component, in reliability tests such as thermal shock resistance tests and PCT tests, the internal stress generated by the difference in thermal expansion coefficient of the connection substrate is likely to cause a connection at the connection point. Increased resistance and peeling of the adhesive.

In addition, when the chip is directly connected to the substrate through an adhesive, if a printed substrate such as FR4 base material is used as the connection substrate, a flexible circuit board using a polymer film such as polyimide or polyester as the base material or After the glass substrate is connected, the chip and the substrate tend to warp due to the internal stress generated by the difference in thermal expansion coefficient between the chip and the chip. Furthermore, when the chip is pressure-bonded to the substrate and the adhesive flows, many voids are generated at the connection interface, and there is a problem that the moisture resistance is lowered.

Contents of the invention

The object of the present invention is to provide an adhesive for circuit connection, which can suppress the increase of the connection impedance at the connection due to the internal stress caused by the difference in thermal expansion rate, the peeling of the adhesive and the flexure of the chip and the substrate. song.

The circuit-connecting adhesive of the present invention is a heat-adhesive adhesive that electrically connects the electrodes in the pressing direction by heating and pressing the opposing circuit electrodes, and the above-mentioned adhesive has the following characteristics, that is, : It contains dispersed rubber particles with an average particle size of 10 μm or less and a thermally cured reactive resin. The DSC (differential scanning calorimetry) of the adhesive has a heating onset temperature of 60°C or more, and 80% of the curing reaction The end temperature is below 260°C.

In addition, the adhesive of the present invention preferably has a calorific value measured by DSC of 50 to 140 J/g from the exothermic start temperature to the temperature at which 80% of the curing reaction is completed.

Furthermore, the 60% end temperature of the curing reaction of the adhesive of the present invention measured by DSC is preferably below 160°C.

Furthermore, the reactive resin preferably contains an epoxy resin and a latent curing agent.

Furthermore, the latent curing agent is preferably a sulfonium salt.

In addition, the binder of the present invention may contain 0.1 to 30% by volume of conductive particles existing in a dispersed state.

The adhesives of the present invention are intended to include both film-like adhesives and paste-like adhesives, but preferably film-like adhesives.

When the adhesive of the present invention is formed into a film, it may contain a polymer substance that forms a film.

In addition, the film of the present invention preferably has an elastic modulus of 50 to 1000 MPa at 25°C.

If the present invention is used, the internal stress generated in reliability tests such as thermal shock resistance test and PCT test can be absorbed, and even after the reliability test, there is no increase in the connection resistance of the connection and no peeling of the adhesive. An adhesive having improved connection reliability can be obtained. In addition, according to the present invention, when the chip is actually mounted on the LCD panel, since the deflection of the substrate is reduced, its adverse effect on the display quality can be suppressed. That is, it is possible to suppress occurrence of display unevenness due to a change in the gap of the display surface due to the occurrence of warping.

Therefore, the adhesive for circuit connection of the present invention is most suitable for electrically connecting only the LCB board and the TAB, the TAB and the printed board, the LCD board and the IC chip, and the IC chip and the printed board in the direction of pressure at the time of connection.

Detailed ways

The binder of the present invention contains rubber particles having an average particle diameter of 10 μm or less in a dispersed state in the binder. The purpose of containing rubber particles is to relieve the internal stress generated in the reliability test, prevent the peeling of the adhesive, and reduce the deflection of the substrate.

The average particle diameter of the rubber particles is preferably 0.1 to 10 μm, particularly preferably 0.1 to 5 μm. In addition, it is particularly preferable that rubber particles having an average particle diameter or less account for 80% or more of the particle diameter distribution.

The rubber particles of the present invention are not particularly limited as long as they are rubber particles with a glass transition temperature below 25°C. For example, butadiene rubber, polypropylene rubber, styrene-butadiene rubber, nitrile rubber, silicone rubber, etc. can be used. .

Among the above-mentioned rubber particles, silicone rubber particles are preferably used because they are excellent in dispersibility in addition to being excellent in solvent resistance. Silicone rubber particles can be prepared by adding silane compound or methyltrialkoxysilane and/or its partial hydrolyzed condensate to an alkaline substance such as caustic soda or ammonia to adjust the pH value to above 9. After being immersed in an aqueous ethanol solution, it is hydrolyzed and polycondensed, or it is copolymerized with organosiloxane. In addition, in order to improve the dispersibility of the reactive resin, it is best to use silicon microparticles containing functional groups such as hydroxyl groups, epoxy groups, ketimine groups, carboxyl groups, and mercapto groups at molecular ends or intramolecular branches.

In the case of treating the surface of the rubber particles with a coupling agent, it is more preferable to improve the dispersibility to the reactive resin.

The elastic modulus of the rubber particles at room temperature (25° C.) is preferably 1 to 100 MPa, more preferably 1 to 30 MPa in consideration of dispersion of the rubber particles or reduction of interfacial stress during connection. However, when choosing a reactive resin, the reactivity and heat generation of the binder should be considered.

The amount of the rubber particles used relative to the binder composition is preferably 10 to 100 parts by weight relative to 100 parts by weight of the binder composition.

The reactive resin used in the present invention may be, for example, a mixture of an epoxy resin and a latent curing agent, a mixture of a radical reactive resin and an organic peroxide.

As the epoxy resin, one of the following examples may be used alone or two or more of them may be used in combination, but it is not limited to these examples. For example: bisphenol-type epoxy resins derived from chloromethyloxypropane and bisphenol A, F or AD; (クレゾ-ルノボラツク) derived epoxy novolac resin, a naphthalene-based epoxy resin with a naphthalene ring structure, and a glycidyl ammonia complex, glycidyl ether, biphenyl or alicyclic type, etc. in one molecule An epoxy compound with two or more glycidyl groups.

As these epoxy resins, it is preferable to use high-purity products whose concentration of impurity ions such as Na ⁺ , Cl ^- or hydrolyzable chlorine is reduced to 300PPM or less in order to prevent electron migration.

Examples of latent curing agents include the following, but are not limited to these specific examples. For example: imidazole-based, hydrazide-based, complexes of boron trifluoride-amide, sulfonium salts, aminated imides, polyamine salts, and dicyandiamide.

Among these latent curing agents, the curing temperature of sulfonium salt is above 60°C and the temperature at which 60% of its curing reaction is completed is below 160°C. It is most suitable for its excellent low-temperature reactivity and long effective life. As sulfonium salts, particularly suitable are sulfonium salts represented by the general formula (1)

However, in formula (1), R1 is an electron-attracting group, such as: nitroso, carbonyl, carboxyl, cyano, trialkylammonium, methyl fluoride; R2 and R3 are electron-donating groups, such as : amino, hydroxyl, methyl; Y is a non-nuclear anion, for example: hexafluoroarsenate, hexafluoroantimonate.

The usage-amount of a sulfonium salt is preferably 2-20 weight part with respect to an epoxy resin.

It is preferable to mix dispersed conductive particles in the adhesive of the present invention, the purpose of which is to make the adhesive have anisotropic heteroelectricity in order to compensate for height errors of chip bumps or substrate electrodes.

The amount of the reactive resin used with respect to the binder is preferably 20 to 100 parts by weight relative to 100 parts by weight of the binder.

As the conductive particles of the present invention, metal particles such as Au, Ag, Cu, and solder can be used, but are not limited to these examples. It is best to set Ni, Cu, Au, solder and other conductive layers on the surface of polystyrene and other polymer spherical core materials. In addition, on the surface of conductive particles, surface layers such as Sn and Au solder can also be formed. The purpose of further forming the surface layer is to improve conductivity by combining with the bottom layer (conductive layer). The particle size of the conductive particles must be smaller than the minimum interval between electrodes on the substrate. In addition, when the electrode has a height error, the particle size of the conductive particles is preferably larger than the height error, specifically 1-10 μm. In addition, the amount of conductive particles dispersed in the binder is preferably 0.1 to 30% by volume, particularly preferably 0.2 to 15% by volume.

A dispersed inorganic filler may be mixed in the binder of the present invention.

Examples of inorganic fillers usable in the present invention include, but are not limited to, powders such as fused silica, crystalline silica, calcium silicate, alumina, and calcium carbonate.

The amount of the inorganic filler used is preferably 10 to 200 parts by weight relative to 100 parts by weight of the binder composition. Especially preferably, it is 20-90 weight part. In order to reduce the coefficient of thermal expansion, the greater the amount of inorganic filler used, the better the effect; however, if the amount is too large, the adhesion will decrease or the conductivity between electrodes will be poor, and if the amount is too small, the coefficient of thermal expansion will not be sufficiently reduced.

The average particle size of the inorganic filler is preferably 3 μm or less from the viewpoint of preventing poor electrical conduction at the junction. In addition, it is preferable to use a spherical filler as the inorganic filler from the viewpoint of preventing a decrease in fluidity of the resin during connection and preventing damage to the passivation film of the chip. Inorganic fillers can be mixed and dispersed regardless of whether the binder contains conductive particles or not.

In order to form a film more easily, thermoplastic resins such as phenoxy resins, polyester resins, and polyamide resins (hereinafter referred to as film-forming polymers) may also be added to the binder of the present invention. These film-forming polymers have the effect of relieving stress during curing of the reactive resin. It is especially preferable that the film-forming polymer contributes to improvement of adhesion when it has a functional group such as a hydroxyl group.

In order to make the adhesive of the present invention into a film shape, the following method can be adopted, that is, the adhesive composition composed of these reactive resins and latent curing agents is dissolved or dispersed in an organic solvent to form a thin film. Liquid, and then coated on the base material that can be peeled off, the solvent can be removed below the active temperature of the curing agent. The solvent used at this time is preferably a mixed solvent of an aromatic hydrocarbon system and an oxygen-containing system that is beneficial to improve the solubility of the material.

The adhesive film of the present invention can have an elastic modulus (25° C.) of 50-1000 MPa, preferably 70-500 MPa, by adjusting the amount of reactive resin, rubber particles, and film-forming polymer materials used. When the elastic modulus of the adhesive film exceeds 1000 MPa, the film cannot be attached to the circuit board, and the adhesive film tends to be peeled off from the base material film when the film is cut to a predetermined width. In addition, if the elastic modulus is less than 50 MPa, when the base material film is rolled into a roll of 10M or more, the adhesive film will stick to the back of the base material film, making it difficult to stick the adhesive film to the circuit board. tendency. In addition, at this time, since the content of the low-molecular reactive resin increases, many voids tend to be generated during crimping. In addition, the elastic modulus of the adhesive film (storage elastic modulus: film thickness for measurement: 10 μm) can be obtained with a viscoelasticity measuring device (heating rate: 10° C./min., frequency: 1 Hz).

The reactivity of the binder can be measured by DSC (rate of temperature increase: 10° C./minute). The heating start temperature of the adhesive of the present invention using DSC is above 60°C, and the end temperature of 80% of the curing reaction of the adhesive is below 260°C. Adjustments to these temperatures are made by the choice of reactive resins added to the binder. In addition, the temperature at which 60% of the curing reaction is completed is preferably 160°C or lower.

The calorific value of the curing reaction of the adhesive of the present invention can also be obtained by DSC (rate of temperature increase: 10°C/min). The calorific value is preferably 50-140 J/g, especially 60-120 J/g, especially 60-100 J/g. By changing the reactive resin, rubber particles, film-forming polymers, etc. The amount used is adjusted. If the calorific value of the adhesive exceeds 140 joules/g, the internal stress will increase due to factors such as the curing shrinkage force of the adhesive and the increase in elastic modulus. When connecting circuits, there will be circuit board flexures, resulting in reliable connections. There is a tendency to reduce the performance or the characteristics of electronic parts. In addition, when the calorific value is less than 50 joules/g, there is a tendency for adhesiveness and connection reliability to decrease due to insufficient curing of the adhesive.

DSC uses the zero point method of supplying or removing heat as the measurement principle to continuously eliminate the temperature difference with a standard sample that does not generate heat or absorb heat within the measurement temperature range. It can also be measured using a commercially available measurement device. The reaction of the binder is an exothermic reaction. If the temperature is raised at a certain heating rate, the reaction of the sample will generate heat. This calorific value is output to a graph, and the baseline is used as a reference, and the area enclosed by the calorific curve and the baseline is obtained, and this is regarded as a calorific value. Measurement was performed from room temperature (25°C) to about 300°C at a temperature increase rate of 10°C/min to obtain the above-mentioned calorific value. This is done completely automatically and can be easily done using it. In addition, the completion temperature of 80% of the curing reaction can be obtained from the area of the heat generation.

Embodiment one

In 115 g of ethyl acetate, 50 g of phenoxy resin (manufactured by Unionka Bird Co., Ltd., PKHC) was dissolved to obtain a 30% by weight phenoxy resin solution.

As silicone, add methyltrimethoxysilane to ethanol aqueous solution with pH value of 12 stirred at 300 rpm at 20°C to hydrolyze and condense to obtain a storage elastic modulus of 8 MPa at 25°C and an average particle size Spherical microparticles with a diameter of 2 μm.

30 grams of silicone microparticles containing phenoxy resin solution (45 grams of phenoxy resin by solid weight ratio), liquid epoxy resin of microcapsule type latent curing agent (epoxy equivalent 185, manufactured by Asahi Kasei Co., Ltd., Nobakuyua HX--3941) 20 grams, 50 grams of bisphenol A type epoxy resin (epoxy equivalent 180) are mixed, will form the conductive particle of Au layer on the surface of polystyrene core (diameter: 5 μ m) with 6 volume % dispersed therein to prepare a solution for film coating. Subsequently, the solution is coated on a PET (polyethylene terephthalate, base material film, separator) film with a thickness of 50 μm on one side of the film with a coating device, and dried by hot air at 70 ° C. After 10 minutes, a film-like adhesive having an adhesive layer thickness of 45 μm was obtained. Regarding the adhesive, the reaction start time, the reaction end time, the end temperature of 60% and 80% of the curing reaction, the heat generation of DSC until the end of 80% of the curing reaction, and the heat generation of DSC until the complete end of the curing reaction The heat and modulus of elasticity were measured, and the results are shown in Table 1.

Next, a chip (10×10 mm, thickness 500 μm) with gold bumps (area 80×80 μm, interval 30 μm, height 15 μm, number of bumps 288) was bonded to a chip (10×10 mm, thickness 500 μm) with the chip as follows using the obtained film-like adhesive. The electrodes corresponding to the circuit electrodes are connected to the Ni/Au plated Cu circuit printed board.

Paste the film-like adhesive (12×12mm) on the Ni/Au-plated Cu circuit printed board (electrode height 20mm, thickness 0.8mm) at 80°C, under the pressure of 1.0MPa (10kg force/ ^cm2 ), peel off Separator, so that the position of the flange of the chip and the Cu circuit printed board (thickness 0.8mm) plated with Ni/Au coincide. Subsequently, heating and pressure were carried out from above the chip under the conditions of 180° C., 75 g/each flange, and 20 seconds, so as to realize the connection.

The deflection of the chip after this connection was 1 μm (deflection convex toward the chip). In addition, the connection impedance after this connection is up to 15MΩ per flange, 8MΩ on average, and the insulation resistance is above ^188Ω . These values are even after 1000 cycles of thermal shock resistance test at -55--125°C, PCT test (121°C, 0.2MPa (2 atmospheres)) for 200 hours, and immersion in 260°C brazing bath for 10 seconds. No change, indicating its good connection reliability.

Embodiment two

Except that 10% by volume of conductive particles was dispersed in the binder, the rest was the same as that of Example 1 to obtain a film coating solution.

Subsequently, use the coating device to coat the solution on the surface-treated PET film on one side of the film with a thickness of 50 μm, and dry it with hot air at 70°C for 10 minutes to obtain a film-like bond with an adhesive layer thickness of 10 μm. Agent a.

Subsequently, in the process of preparing the solution for coating as described above, except that the conductive ions forming the Au layer were not dispersed in the solution, the solution for thin film coating was prepared by the same method as above, and the solution was prepared using a coating device. Coated on a PET film surface-treated on one side of a film with a thickness of 50 μm, and dried with hot air at 70° C. for 10 minutes to obtain a film-shaped adhesive b with an adhesive layer thickness of 15 μm. Further, the obtained film-like adhesives a and b were heated at 40° C., and were laminated with a roll laminator to form an anisotropic conductive film with a two-layer structure.

About this binder, it measured similarly to Example 1, and the result is shown in Table 1.

Next, using the obtained anisotropic conductive film, chips (1.7×17 mm, thickness: 1.7×17 mm, thickness: 1.7×17 mm, thickness: : 500μm) is connected to a glass substrate (thickness: 1.1mm) with an ITO circuit. After pasting the anisotropic conductive film (2×20mm) on the glass substrate with the ITO circuit under the pressure of 1MPa (10kg/ ^cm2 ) at 80°C, peel off the separator to make the flange of the chip and the ITO circuit The position of the glass substrate of the circuit coincides. Subsequently, under the conditions of 190° C., 40 g/each flange, and 10 seconds, heating and pressing are carried out from above the chip, so as to realize this connection. The deflection of the chip after this connection was 2.5 μm. In addition, the connection impedance is 80MΩ at the highest per flange, 30MΩ on average, and the insulation resistance is above 10 ⁸ Ω. These values do not change even after 1000 cycles of thermal shock resistance test at -40--100 °C, high temperature, high humidity (85 °C, 85% RH, 1000 hours) test, indicating its good connection reliability.

Embodiment three

50 g of phenoxy resin (manufactured by Unionka Bird, PKHC) was dissolved in 115 g of ethyl acetate to prepare a 30% solution.

Bisphenol A type epoxy resin (epoxy equivalent 180) in which 60 g of phenoxy resin having a solid weight ratio and 20% by weight of acrylic particles (storage modulus of elasticity 3 MPa) having an average particle diameter of 0.2 μm are dispersed 25 grams, 5 grams of bisphenol A type solid epoxy resin (epoxy equivalent: 185), 3 grams of P～acetate phenyl methanesulfonate (non-nuclear anion: hexafluoroantimonate) are mixed, and then mixed in 10% by volume of conductive particles forming a gold layer on the surface of a polystyrene-based core (diameter: 3 μm) was dispersed and mixed therein to prepare a thin film coating solution.

Subsequently, the solution was coated on a surface-treated PET film on one side of a film with a thickness of 50 μm using a coating device, and dried by hot air at 70° C. for 10 minutes to obtain an adhesive layer with a thickness of 10 μm. film-like adhesive c.

Subsequently, in the above-mentioned process of making the solution for thin film coating, except that the conductive particles forming the Au layer were not dispersed in the solution, the same method as above was used to prepare the solution for thin film coating. This solution is coated on the PET film after surface treatment on one side of the film with a thickness of 50 μm, and dried by hot air at 70°C for 10 minutes to obtain a film-like adhesive with an adhesive layer thickness of 15 μm. .

While heating the obtained film-like adhesives c and d at 40° C., an anisotropic conductive film laminated in a two-layer structure was produced with a roll laminator. About this adhesive film, it measured similarly to Example 1. The results are shown in Table 1.

Next, using the prepared anisotropic conductive film, chips (1.7×17 mm, thickness: 500 μm) with gold bumps (area: 50×50 μm, interval: 20 μm, height: 15 μm, number of bumps: 362) were fabricated as follows ) is connected to a glass substrate (thickness: 1.1mm) with an ITO circuit. Paste the anisotropic conductive film (2×20mm) on the glass substrate with ITO circuit at 80°C with a pressure of 1MPA (10kg force/ ^cm2 ), peel off the separator, and make the flange of the chip and the ITO circuit The position of the glass substrate matches. Subsequently, heating and pressure were carried out from above the chip under the conditions of 150° C., 40 g/each flange, and 10 seconds, so as to realize this connection. The deflection of the chip after this connection was 1.5 μm. In addition, the maximum connection impedance of each flange is 50MΩ, the average is 20MΩ, and the saturated edge resistance is above 10 ⁸ Ω. Even if these values are subjected to 1000 cycles of thermal shock resistance tests at -40 to 100°C, high temperature and high humidity (85°C /85%RH, 1000 hours) test also showed no change, indicating good connection reliability.

Comparative example one

Table 1 shows the results of a comparison test with Example 1 using an anisotropic conductive film FC-110A (manufactured by Hitachi Chemical Industries, Ltd., film thickness: 45 μm) not mixed with rubber particles.

Next, using the above-mentioned film-like adhesive, a chip (10×10 mm, thickness: 500 μm) with gold bumps (area: 80×80 μm, pitch: 30 μm, height: 15 μm, number of bumps: 288) was placed as follows Ni/Au plated Cu circuit printed board for connection. Paste the film adhesive (12×12mm) on the Ni/Au-plated Cu circuit printed board (electrode height: 20μm, thickness: 0.8mm) at 80°C, under the pressure of 1MPa (10kg/ ^cm2 ), peel off After the separator, align the flange of the chip with the position of the Ni/Au-plated Cu circuit printed board. Subsequently, under the conditions of 190° C., 75 g/each flange, and 10 seconds, heating and pressing are carried out from above the chip, so as to realize this connection. The deflection of the chip after this connection was 7.2 μm (deflection convex toward the chip). In addition, the connection impedance after this connection is a maximum of 20 MΩ per flange, an average of 10 MΩ, and an insulation resistance of 10 ⁸ Ω or more. The connection impedance has been subjected to 1000 cycles of thermal shock resistance test at -55 to 125°C, PCT test (121°C, 2MPA (2 atmospheres)) for 200 hours, and immersion in a brazing bath at 260°C for 10 seconds, in addition to increasing Also produced some cases of poor connection.

Comparative example two

Anisotropic conductive film AC-8401 (manufactured by Hitachi Chemical Industry Co., Ltd. , Film thickness: 23 μm) comparative test was carried out relative to Example 2, and the results are shown in Table 1.

Next, using this anisotropic conductive film, a chip (1.7×17 mm, thickness: 500 μm) with gold bumps (area: 50×50 μm, interval 20 μm, height: 15 μm, number of bumps: 362) and a chip with ITO The glass substrate (thickness: 1.1mm) of the circuit is connected. After pasting the anisotropic conductive film (2×20mm) on the glass substrate with ITO circuit at 80°C with a pressure of 1 MPa, the separator was peeled off to align the flange of the chip with the glass substrate with ITO circuit. Subsequently, heat and pressurize from above the chip under the conditions of 190° C., 40 g/each flange, and 10 seconds, to realize the connection. The deflection of the chip connected in this case was 8.2 μm, and the deflection was larger than that of Example 2.

Table 1

project Example 1 Example 2 Example 3 Comparative example 1 Comparative example 2 Reaction start temperature (°C) 90 90 80 90 90 Reaction end temperature (°C) 190 200 240 206 205 80% end temperature of curing reaction (°C) 160 160 230 180 180 60% end temperature of curing reaction (°C) 145 145 160 160 150 DSC heating value until 80% of the curing reaction is completed (J/g) 75 70 120 180 160 Calorific value of DSC until the end of curing reaction (J/g) 90 85 150 200 200 Modulus of elasticity (25℃, MPa) 600 600 200 2000 2000

Claims (6)

1. A bonding agent for circuit connection, which is a thermally adhesive bonding agent that realizes electrical connection between the electrodes in the pressing direction through heating and pressurizing the opposite circuit electrodes, characterized in that: the above bonding The adhesive contains a thermally curable reactive resin. The above-mentioned adhesive has a minimum exothermic start temperature of 60°C measured by DSC, and a maximum end temperature of 80% of the curing reaction is 260°C until 80% of the curing reaction ends. The calorific value is 50-140 joules/g, and the heating rate of the DSC test is 10°C/min; the adhesive contains inorganic fillers and silicone rubber particles with an average particle size of 10 μm or less. 2. The adhesive for circuit connection according to claim 1, characterized in that: the thermally cured reactive resin is epoxy resin and latent curing agent. 3. The adhesive for circuit connection according to claim 1, wherein the adhesive contains a film-forming polymer. 4. The adhesive for circuit connection according to claim 3, wherein a thermoplastic resin, ie, a phenoxy resin, a polyester resin, or a polyamide resin, is added to the adhesive as a film-forming polymer. 5. The adhesive for circuit connection according to claim 3, wherein the film-forming polymer is a phenoxy resin. 6. The adhesive for circuit connection according to any one of claims 1-5, characterized in that the adhesive contains conductive particles, and the particle size of the conductive particles is 1-10 μm.