JP2013023671A - Film-like anisotropic conductive adhesive and inspection method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a film-like anisotropic conductive adhesive that satisfies a predetermined level in storage reliability, low-temperature curability, insulation stability, and connection reliability; and a simple inspection method that determines whether the connected body obtained has a risk of having unsatisfactory connection reliability and insulation stability or not, according to the conditions of the film-like anisotropic conductive adhesive.SOLUTION: The film-like anisotropic conductive adhesive includes (A) an epoxy resin, (B) a conductive particle, and (C) a microcapsule-type imidazole-based latent curing agent. The chlorine content in the gas obtained by combusting the film-like anisotropic conductive adhesive is less than 600 ppm. The inspection method includes the steps of: combusting a test sample obtained by pulverizing the film-like anisotropic conductive adhesive; and determining whether the chlorine content in the combustion gas obtained is less than 600 ppm or not.

Description

  The present invention relates to a film-like anisotropic conductive adhesive used for bonding circuit boards such as LCD glass panels and flexible printed wiring boards (FPCs) and a method for inspecting the film, and particularly to connection reliability and insulation. High-performance film-like anisotropic conductive adhesive, and inspection that can efficiently sort film-like anisotropic conductive adhesive that may not be able to obtain a joined body that satisfies the specified level of insulation performance and connection reliability Regarding the method.

  Bonding between circuit boards, for example, as shown in FIG. 1, an LCD glass panel 1 in which electrodes 1a, 1a,... Are juxtaposed at a predetermined interval, and a flexible print in which electrodes 2a, 2a are juxtaposed at a predetermined interval For joining the wiring board (FPC) 2, a film-like anisotropic conductive adhesive 3 is used.

  Usually, the LCD glass panel 1 and the FPC 2 are faced to each other so that the pair of electrodes 1a and 2a face each other, and a film-like anisotropic conductive adhesive 3 is sandwiched between them. (FPC 2 in FIG. 1) is performed by heating and pressurizing the other joining member (the glass panel 1 in FIG. 1) with the press thermal head 5 through the cushion material 4. By heating and pressing using the press thermal head 5, the distance between the opposing electrodes (1a and 2a) is narrowed, and the film-like anisotropic conductive adhesive 3 melts and flows, so that the electrodes (1a -1a and 2a-2a) and a gap between opposing electrodes (1a and 2a).

  FIG. 2 shows a state where the film-like anisotropic conductive adhesive 3 is used for bonding. In general, the flow of the conductive particles (indicated by 3a in FIG. 2) is slower than the flow of the molten resin, and therefore remains in the gap between the opposing electrodes (1a and 2a). Therefore, the LCD glass panel 1 and the FPC 2 Is in a conductive state. On the other hand, in each of the glass panel 1 and the FPC 2 which are the respective joining members, the adhesive strength of the joined body is ensured by filling the gap between the adjacent electrodes with the cured product of the conductive adhesive.

  As such a film-like anisotropic conductive adhesive for bonding circuit boards, generally, conductive particles are dispersed in an epoxy resin having excellent performance such as electrical characteristics, thermal characteristics, chemical resistance, and adhesiveness. An epoxy resin composition is used. Moreover, as an epoxy resin curing agent, amine-based curing is possible because it can satisfy both excellent storage stability as a film-like anisotropic conductive adhesive and low-temperature curability that can lower the curing temperature at the time of bonding. A so-called microcapsule type curing agent in which the core of the agent is coated with a specific shell is generally used.

  In the recent electronic equipment field, in order to cope with higher circuit density and improved connection reliability, there is an increasing demand for the insulation stability and reliability of such a film-like anisotropic conductive adhesive. Further, from the viewpoint of productivity, further improvement in low-temperature curability is demanded without impairing storage stability.

  As a microcapsule curing agent capable of achieving both low temperature curing property and storage stability, for example, in Japanese Patent No. 4326524, it is composed of a core containing an amine curing agent and a shell which is a reaction product of an amine curing agent and an epoxy resin. In a masterbatch type curing agent in which the microcapsule type curing agent or the microcapsule type curing agent is dispersed in an epoxy resin, the smaller the total amount of chlorine contained, the epoxy containing these curing agents. It is shown that the resin composition is excellent in storage stability and curability (temperature at which the gel time is less than 5 minutes) (Table 2), and the total chlorine content in the epoxy resin constituting the shell is 400 ppm or less, and amine-based Epoxy resin set containing a microcapsule type curing agent and a masterbatch type curing agent, wherein the total amount of chlorine contained in the curing agent is 400 ppm or less Things have been proposed.

  Similarly, in Japanese Patent No. 4583373, an amine curing agent obtained by the reaction of an amine adduct, a low molecular amine compound, and an epoxy resin is used as a core, and the core is coated with a shell obtained by the reaction of the core and the epoxy resin. In the microcapsule type curing agent or masterbatch type curing agent, it is proposed that the total chlorine content of the epoxy resin is 2000 ppm or less, and the curing agent (epoxy resin composition) using an epoxy resin exceeding the total chlorine content of 2000 ppm. It is shown that the storage stability 1 (evaluated by the rate of increase in viscosity) is poor and the curability 2 (temperature measurement at which the gel time is less than 5 minutes) is inferior (see Tables 3 and 4).

Japanese Patent No. 4326524 Japanese Patent No. 4583373

  As described above, it is known that chlorine contained in the curing agent or the epoxy resin as a component thereof affects the curability and storage stability. The connection literature, insulation properties, etc. are not particularly explained in the above documents.

Since the influence on the connection reliability and insulation of the joined body is different from the storage stability and rapid curability of the curing agent, it was the case where a microcapsule curing agent having a total chlorine content of 400 ppm or less was used. However, the connection reliability and insulation of the joined body are not always satisfied.
Further, by appropriately setting the curing time and the curing temperature according to the type of the curing agent, the film-like anisotropic conductive adhesive is sufficiently softened and melted to obtain a joined body filled in the gap between adjacent electrodes. I can. However, even when the curing conditions (curing temperature, curing time) that can sufficiently soften and melt the film-like anisotropic conductive adhesive are set in this way, the joint does not have predetermined connection reliability and insulation. The body may be obtained.

  The present invention has been made in view of such circumstances, and in a film-like anisotropic conductive adhesive, not only storage reliability and low-temperature curability but also a predetermined level can be satisfied for insulation stability and connection reliability. Providing a film-like anisotropic conductive adhesive and determining whether there is a risk that the connection reliability and insulation stability of the resulting joined body may be insufficient can be determined by the state of the film-like anisotropic conductive adhesive. It is to provide a simple inspection method.

  The present inventors examined not only the curing agent but also various film-like anisotropic conductive adhesives for the total chlorine content, and examined the curing conditions, the connection reliability of the obtained joined body, and the insulation stability. As a result, the present invention has been reached.

  That is, the chlorine content contained in the curing agent not only affects the storage stability and low-temperature curability of the curing agent, but also affects the connection reliability and insulation stability of the resulting joined body. It became clear by the present inventors. And the chlorine content affecting the connection reliability and insulation stability of the joined body, not only those derived from the curing agent, but even when contained in the resin used as the main component, As a result, the present invention was completed.

  The film-like anisotropic conductive adhesive of the present invention is a film-like anisotropic conductive adhesive containing (A) an epoxy resin; (B) conductive particles; and (C) a microcapsule type imidazole-based latent curing agent. And the chlorine amount of the gas obtained by burning this film-like anisotropic conductive adhesive is less than 600 ppm, It is characterized by the above-mentioned.

  The (A) epoxy resin is preferably a mixture of a phenoxy resin, a liquid epoxy resin that is liquid at room temperature, and a solid epoxy resin that is solid at room temperature.

  The total chlorine content contained in the (A) epoxy resin is preferably 1000 ppm or less, and the total chlorine content of the (C) microcapsule type imidazole-based latent curing agent is preferably 400 ppm or less. .

  The inspection method of the present invention is a method for inspecting a film-like anisotropic conductive adhesive containing (A) an epoxy resin; (B) conductive particles; and (C) a microcapsule type imidazole-based latent curing agent, Burning a measurement sample obtained by pulverizing the film-like anisotropic conductive adhesive; and determining whether or not the amount of chlorine contained in the obtained combustion gas is less than 600 ppm.

  The total chlorine amount in this specification is a value obtained by measuring the amount of chlorine gas in the combustion gas obtained by burning the target sample.

  In the film-like anisotropic conductive adhesive of the present invention, the amount of chlorine contained in the film-like anisotropic conductive adhesive is less than 600 ppm, so that not only storage reliability and low-temperature curability but also insulation stability and connection reliability are obtained. It is excellent in the property. Moreover, according to the inspection method of the present invention, it is possible to improve the quality of connection reliability and insulation stability only by inspecting a small amount of sample cut from a film-like anisotropic conductive adhesive manufactured from the same line. Can be done with precision.

It is a figure for demonstrating the joining method of circuit boards using a film-form anisotropic conductive adhesive. It is a schematic cross section which shows the circuit board joined using the film-like anisotropic conductive adhesive.

  Although embodiments of the present invention will be described below, it should be considered that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[Film-like anisotropic conductive adhesive]
The film-like anisotropic conductive adhesive of the present invention is (A) an epoxy resin; (B) a microcapsule type imidazole-based latent curing agent; and (C) a film-like anisotropic conductive adhesive containing conductive particles. And it is a film-form anisotropic conductive adhesive whose chlorine amount measured from the combustion gas obtained by burning the said film-form anisotropic conductive adhesive is less than 600 ppm.

(A) Epoxy resin The epoxy resin may be a polymer having an epoxy group in the molecule, and there is no particular limitation on the degree of polymerization, molecular weight, type, etc., the degree of polymerization is 1 or less, and the weight average molecular weight is 700 or less. A liquid epoxy resin that exhibits a liquid state, a solid epoxy resin having a degree of polymerization of more than 1, a crystalline epoxy resin, and an epoxy having a high molecular weight (usually the degree of polymerization (n) is about 100 or more) corresponding to a phenoxy resin Resin etc. are included.

  Moreover, as a kind of epoxy resin, for example, bisphenol A type, bisphenol F type, bisphenol S type epoxy resin, distilled products thereof, naphthalene type epoxy resin, novolac type epoxy resin, biphenyl type epoxy resin, cyclopentadiene type epoxy resin, Modified epoxy resins such as alkoxy-containing silane-modified epoxy resins, fluorinated epoxy resins, and rubber-modified epoxy resins can be used.

  These epoxy resins may be used alone or in combination with different types of epoxy resins having different molecular weights, reactivity, softening points and the like as necessary. Preferably, a combination of a phenoxy resin and a liquid epoxy resin that is liquid at room temperature, more preferably a combination of a phenoxy resin, a liquid epoxy resin, and a solid epoxy resin that is solid at room temperature.

  The phenoxy resin corresponding to the high molecular weight epoxy resin usually has a softening point of about 80 to 150 ° C. and is solid at room temperature. Since it behaves as a thermoplastic resin, it has good film formability. In addition, the high molecular weight phenoxy resin prevents an abrupt decrease in viscosity due to the flow of the epoxy resin, which occurs at an early stage of the heat treatment for bonding, and includes the epoxy resin and the (B) microcapsule-type latent curing agent. Prevents rapid curing reaction from proceeding. Thereby, the appropriate fluidity during the joining operation is maintained, and the gap between the electrodes on the same surface of the member to be joined (for example, the gap between 2a-2a in FIGS. Resin can flow in, and there are few voids, and a highly uniform joint can be formed. The phenoxy resin preferably has a weight average molecular weight measured by GPC of 30,000 or more, more preferably 40,000 or more, and still more preferably 45,000 or more.

  Since the liquid epoxy resin is in a liquid state at normal temperature, the viscosity is quickly lowered with the start of heating, and the liquid epoxy resin is mixed with the curing agent, so that the reaction can proceed rapidly. The solid epoxy resin has a function of abruptly decreasing the viscosity accompanying the start of heating of the liquid epoxy resin and slowing the progress of the reaction accompanying this. That is, it is useful for viscosity adjustment by suppressing a rapid viscosity drop due to the liquid epoxy resin.

  The content of the epoxy resin in the adhesive composition is usually about 20 to 80% by weight, preferably about 30 to 70% by weight, from the viewpoint of maintaining insulation between electrodes on the same surface.

  Moreover, it is preferable to contain phenoxy resin 20 to 40 weight% (especially 25 to 35 weight%) of resin whole quantity. If it is less than 20% by weight, it is difficult to maintain the solidity of the entire composition, and it tends to be difficult to produce a film-like anisotropic conductive adhesive.

  Here, the total chlorine content of the epoxy resin used in the present invention (when using a plurality of combinations) is preferably 1000 ppm or less, more preferably 800 ppm or less. Such chlorine is usually derived from epichlorohydrin used as an epoxy resin raw material in the process of resin synthesis and remaining in the resin. This is because the amount of chlorine contained in the resin affects the connection reliability and insulation stability of the obtained joined body.

(B) Microcapsule type imidazole-type latent curing agent Microcapsule-type latent curing agent is a product in which an imidazole derivative acting as a curing agent for epoxy resin and phenoxy resin is used as a core, and the core is covered with a film. is there.

  The core imidazole derivative is usually a solid powder at normal temperature, and an adduct of an epoxy compound and an imidazole compound or an imidazole compound carboxylate is pulverized to an appropriate particle size.

  Examples of the imidazole derivatives include imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1 -Benzyl-2-ethyl-5-methylimidazole, 2-phenyl-3-methyl-5-hydroxymethylimidazole and the like. Examples of the epoxy compound include glycidyl ether type epoxy resins such as bisphenol A, bisphenol F, and brominated bisphenol A, dimer acid diglycidyl ester, and phthalic acid diglycidyl ester.

  As the coating film, a film having a urethane bond is usually preferably used because of its good compatibility with the epoxy resin. Specifically, a film obtained by polymerizing a compound having an isocyanate group with an OH group on the powder surface, which is a main body of the curing agent, is preferably used.

  Examples of the isocyanate compound include tetramethylene diisocyanate, hexamethylene diisocyanate, tolylene diisocyanate, xylene diisocyanate, and diphenylmethane diisocyanate. A film is formed by polymerizing these isocyanate compounds on the surface of the imidazole compound at room temperature.

  In general, the microcapsule-type latent curing agent as described above preferably has an average particle size of 1 to 10 μm. Here, the average particle size is measured by measuring microcapsule particles taken out as a solid content with a xylene organic solvent using a laser diffraction type measuring device RODOS SR type (SYMPATEC HEROS & RODOS), and calculating the volume averaged average particle size as the average particle size. The diameter.

The microcapsule type latent curing agent may be a masterbatch type latent curing agent in which a microcapsule type latent curing agent is dispersed in a liquid epoxy resin.
Moreover, you may use a commercial item and NovaCure series by Asahi Kasei E-materials company is mentioned as a typical commercial item.

  The microcapsule-type latent curing agent used in the present invention is an epoxy resin (A) used in combination so that the total chlorine content as a film-like anisotropic conductive adhesive is less than 600 ppm, preferably 500 ppm or less. It is preferable to select according to the total amount of chlorine contained. From the viewpoint of storage stability and low temperature curability of the curing agent, it is preferable to use a microcapsule type imidazole-based latent curing agent having a concentration of 400 ppm or less, preferably 100 ppm or less.

  The microcapsule type imidazole-based latent curing agent varies depending on the type and blending amount of the epoxy resin used, other resins described later, rubber, and thermoplastic elastomer, but usually 8 parts per 100 parts by mass of the total resin components. It is preferable to contain -20 mass parts.

(C) Conductive particles The conductive particles may be any particles having conductivity, such as solder particles, nickel particles, gold-plated nickel powder, copper powder, silver powder, nano-sized metal crystals, and metal surfaces. Metal particles such as particles coated with other metals; resin particles such as styrene resin, urethane resin, melamine resin, epoxy resin, acrylic resin, phenol resin, styrene-butadiene resin, gold, nickel, silver, copper, solder, etc. Particles coated with a conductive thin film can be used. The particle size of such conductive particles is not particularly limited, but is usually an average particle size of 0.1 to 5 μm.

  Among these, particles having magnetism are preferably used from the viewpoint that the conductive particles are easily oriented in a predetermined direction (in the present invention, the film thickness direction). Further, from the viewpoint of easily orienting the conductive particles in the thickness direction, conductive particles having an aspect ratio of 5 or more are preferably used. Specifically, a shape in which fine metal particles are connected in a straight chain, or acicular particles are preferably used. Such conductive particles can be oriented in the thickness direction by the action of a magnetic field during film formation.

  Although the content of the conductive particles varies depending on the application, it is an amount that is insufficient to conduct the gap between adjacent electrodes juxtaposed on the same surface, and is an amount that allows conduction between opposing electrodes. Specifically, it is preferably 0.01 to 10% by volume, more preferably 0.01 to 1% by volume, based on the total volume of the conductive adhesive.

(D) Other components In addition to the above components (A), (B), and (C), the film-like anisotropic conductive adhesive of the present invention may further include other thermoplastic resins and other heat as necessary. It may contain a curable resin, rubber, thermoplastic elastomer and the like.

Examples of other thermoplastic resins include acrylic resins, polyamide resins, polyolefin resins, fluororesins, polyester resins, and silicone resins.
Examples of other thermosetting resins include polyimide resins, polyamideimide resins, polyesterimide resins, phenol resins, polyurethane resins, and the like.

Other polymer substances include, for example, rubber-based materials such as epoxidized polybutadiene, acrylic rubber, and nitrile rubber; styrene-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, polyolefin-based thermoplastic elastomers, and polyester-based thermoplastic elastomers. , Polyvinyl chloride-based thermoplastic elastomers, polyurethane-based thermoplastic elastomers, and the like. These may be used alone or in combination of two or more.
Such rubber or thermoplastic elastomer can be a stress relaxation material in which stress is generated in the adhesive interface or inside the adhesive by curing shrinkage. Moreover, flexibility can be imparted to a cured epoxy resin that is generally insufficient in flexibility.

  In addition to the above components, the film-like anisotropic conductive adhesive of the present invention may further contain a reinforcing material, a filler, a coupling agent, a curing accelerator, a flame retardant, and the like as desired.

  As for the other components as described above, those having a low chlorine content are used so that the total chlorine content of the finally obtained anisotropic anisotropic conductive adhesive is less than 600 ppm, preferably 500 ppm or less. Is preferred.

[Manufacture of film-like anisotropic conductive adhesive]
The film-like anisotropic conductive adhesive of the present invention is obtained by forming a composition for an adhesive containing the above components into a film. Although the manufacturing method of a film-form anisotropic conductive adhesive is not specifically limited, Usually, it manufactures with the following methods.

The above components (A), (B), (C) and, if necessary, (D) other components are blended in a predetermined amount and dissolved in a solvent to prepare an adhesive coating solution. Examples of the solvent include toluene, xylene, benzene, ethyl acetate, butyl acetate, aromatic hydrocarbons and the like. Further, when the film-like anisotropic conductive adhesive uses acicular particles (for example, conductive particles having an aspect ratio of 5 or more) as the conductive particles, the conductive particles can be oriented in the thickness direction during drying. A solvent having a high volatilization rate is preferably used. Specifically, ester systems such as PGMEA and PMA are preferably used.
Although it does not specifically limit as solid content rate of the said solution for coating, It is preferable that it is 40 to 70 weight%.

The prepared coating solution is coated on a base film, cast, and dried by heating to form a film.
The drying temperature for producing the film-like anisotropic conductive adhesive varies depending on the organic solvent used, but is usually about 60 to 80 ° C.

When the film-like anisotropic conductive adhesive contains magnetic particles or conductive particles having an aspect ratio of 5 or more as the component (C), the conductive particles are passed through a magnetic field before or simultaneously with heating and drying. It is preferable to align in the thickness direction.
Although the thickness of a film-form anisotropic conductive adhesive is not specifically limited, Usually, it is 10-50 micrometers, Preferably it is 15-40 micrometers.

  The film-like anisotropic conductive adhesive of the present invention obtained as described above has a total chlorine content measured by a combustion method of less than 600 ppm, preferably 500 ppm or less. Here, the total chlorine amount measured by the combustion method refers to the chlorine amount in the combustion gas obtained by burning the pulverized product of the film-like anisotropic conductive adhesive. The amount of chlorine measured in this way is not only the chloride-derived chlorine measured by hydrolysis, silver nitrate titration, etc., but also the amount of chlorine in the organic compound (C-Cl) bonded state. . Therefore, the total amount of chlorine is measured including the amount of chlorine contained in the residual monomer of the epoxy resin raw material such as epichlorohydrin.

  As described above, a film-like anisotropic conductive adhesive containing a small amount of total chlorine as a film-like anisotropic conductive adhesive is excellent in initial connection resistance, connection reliability, and insulation stability. In other words, a film-like anisotropic conductive adhesive having a total chlorine content of 600 ppm or more is inferior in connection reliability and insulation stability. The reason is not clear, but the chlorine content contained in the film-like anisotropic conductive adhesive is released over time under the conditions of high temperature and high humidity and voltage application, corroding the electrodes and conductive particles, It is thought that the generated metal ions may cause a short circuit between the electrodes. Therefore, it is considered that connection reliability and insulation stability can be improved by reducing the amount of chlorine that can exhibit such behavior.

[Method for producing circuit board assembly]
As a circuit board joining method using the film-like anisotropic conductive adhesive of the present invention as described above, it can be joined by a conventionally known method. Specifically, as shown in FIG. 1, two circuit boards in which a plurality of electrodes are juxtaposed face each other so that the electrodes face each other, and the film-like anisotropic of the present invention is interposed between the circuit boards. What is necessary is just to heat-press and interpose a conductive adhesive.

  What is necessary is just to set heat-pressurization conditions suitably according to the composition of the latent hardening agent and film-like anisotropic conductive adhesive to be used. In short, it is only necessary to set the heating and pressing conditions such that the resin component in the adhesive is sufficiently softened and melted and can flow into the gap between the adjacent electrodes and can be reactively cured.

  The heating and pressing method is not particularly limited, but is usually performed using a pressing tool such as a press machine or a pressing member heated to a predetermined temperature. A cushion material may be appropriately interposed between the circuit board serving as the adherend and the pressing tool.

  Although heating temperature is not specifically limited, Usually, 150-220 degreeC, Preferably it is 170-200 degreeC, More preferably, it is 180-200 degreeC. Here, the heating temperature is a temperature that the film-like anisotropic conductive adhesive should reach. For example, a thin thermocouple is embedded in the film-like anisotropic conductive adhesive, and the glass panel 1 and the flexible print. A method of actually measuring by sandwiching between the wiring boards 2 is used.

  The pressurizing pressure is not particularly limited, but is usually 2 to 6 MPa, preferably 3 to 5 MPa. The pressurization time is 15 seconds or less, preferably 10 seconds or less, more preferably 5 seconds or less from the viewpoint of the productivity of the joined body.

[Inspection method for film-like anisotropic conductive adhesive]
The method for inspecting a film-like anisotropic conductive adhesive of the present invention includes a step of burning a measurement sample obtained by pulverizing a film-like anisotropic conductive adhesive to be inspected, and in the obtained combustion gas A step of determining whether or not the amount of chlorine contained is less than 600 ppm.

The pulverization method can be carried out using a known plastic film pulverizer such as a cutter or scissors.
Although it does not specifically limit as the quantity of the sample for a measurement used for combustion, What is necessary is just about 20 mg-200 mg.

Although the combustion method and the combustion conditions are not particularly limited, it is preferable to comply with BS EN 14582: 2007. Specifically, high-pressure oxygen or argon is enclosed in a combustion tube made of quartz or stainless steel, and electrically It is preferable to burn with a spark.
The method for capturing the combustion gas is not particularly limited. For example, the combustion may be performed in a sealed container, and repaired to another container with a duct or the like from an outlet opening in the container ceiling. May be directly supplied to the chlorine content measuring apparatus.

Although the measuring method of the amount of chlorine gas is not specifically limited, For example, it can carry out by ion chromatography and gas chromatography. The trapped chlorine gas may be a solution in which the gas is dissolved in an appropriate solvent depending on the measurement device to be used.
In this case, examples of the solvent that can be used include water, methanol, acetonitrile, and a mixed solution thereof.

  The total chlorine content concentration (ppm) in the film-like anisotropic conductive adhesive is determined by dividing the measured value (the amount of chlorine contained) by the amount of sample used for the measurement. It is determined whether or not the total chlorine amount is 600 ppm or more, and preferably exceeds 500 ppm. A film-like anisotropic conductive adhesive of 600ppm or more satisfies the connection or insulation reliability in connection conditions such as low temperature and short time, and in use environment such as fine pitch circuit and high voltage application, though there is no problem in normal use environment. This is because there is a high possibility that this is not possible.

  According to such an inspection method of the present invention, it is highly likely that a bonded body that satisfies a predetermined level of connection reliability and insulation stability cannot be obtained simply by measuring the amount of combustion and total chlorine. The conductive adhesive can be sorted and removed from the shipping line without forming a bonded body. Chlorine content shows almost constant value regardless of the location of the film-like anisotropic conductive adhesive that is continuously produced. Therefore, the film-like anisotropic conductive adhesive produced from the same line with a small amount of sample. The quality of the agent can be selected efficiently. Then, by inspecting at the stage of the film-like anisotropic conductive adhesive, the film-like anisotropic conductive adhesive that has a high possibility of not satisfying the predetermined level with respect to connection reliability and insulation stability is manufactured at the assembly manufacturing site. As a result, the yield of the bonded body can be reduced.

  The best mode for carrying out the present invention will be described with reference to examples. The examples are not intended to limit the scope of the invention.

[Evaluation measurement method]
(1) Total chlorine content (ppm)
The film to be measured was finely pulverized and completely burned, the generated gas was trapped in water, and the resulting solution was analyzed by ion chromatography to determine the chlorine content.

(2) Insulation stability FPC in which 50 μm wide Au-plated Cu circuits are arranged in a comb shape with an interval of 50 μm and a glass substrate on which Al circuits of the same width are formed were prepared.
Both are arranged so that the electrodes face each other, and the anisotropic conductive film obtained above is sandwiched, and cured under curing conditions 1 (heating temperature: 190 ° C., pressing pressure: 3 MPa, pressing time: 15 seconds). To obtain a joined body. The obtained joined body was left in a high-temperature and high-humidity tank set at 85 ° C. and 85% RH, and the insulation resistance was continuously measured while applying a voltage of 50 V between adjacent electrodes of the comb circuit. The time until the value became 10 MΩ or less was measured.

(3) Initial resistance (Ω)
An FPC in which 124 Cu-plated Au circuits having a width of 50 μm and a height of 18 μm were arranged at intervals of 50 μm and a glass substrate on which ITO circuits having a width of 150 μm were formed at intervals of 50 μm were prepared. Both are arranged facing each other so as to form a daisy chain capable of measuring connection resistance at 124 consecutive locations, and the anisotropic conductive film obtained above is sandwiched, and curing condition 2 (heating temperature: heating temperature: It was cured at 180 ° C., pressurization pressure: 3 MPa, pressurization time: 5 seconds, and a joined body was obtained.
In the obtained joined body, the resistance value of 124 consecutive points connected via ITO, adhesive, and Au-plated Cu circuit is obtained by the four-terminal method, and the value is divided by 124 to obtain one per location. The connection resistance was obtained.

(4) Connection reliability The joined body prepared in (3) was left in a high-temperature and high-humidity tank set at 85 ° C. and 85% RH for 500 hours, and then taken out. The connection resistance per place was calculated.

[Production and evaluation of film-like anisotropic conductive adhesive]
No1:
As phenoxy resin, (a) Epicoat 1256 (weight average molecular weight 50,000) manufactured by JER Corporation, and as epoxy resin, solid epoxy resin ((b) Epicoat 1007 (number average molecular weight 2900) manufactured by JER Corporation and liquid epoxy Resin (Epiclon 4032D manufactured by DIC Corporation) and (d) Fuji Chemical Industries, Ltd. TPAE were used as the thermoplastic elastomer.
As the microcapsule-type latent curing agent, a microcapsule-type imidazole-based curing agent ((e) Asahi Kasei E-Materials Nova Cure LSA-H0910) was used.
As the conductive particles, linear nickel fine particles having a chain length distribution from 1 μm to 12 μm were used.

  The above (a) to (e) are mixed at a mass ratio of a: b: c: d: e = 25: 25: 10: 5: 35, and propylene glycol monomethyl ether acetate (PMA) and butyl acetate are mixed. After dissolving in a mixed solvent (mixing ratio 90/10), the mixture was mixed for 3 minutes using a centrifugal mixer to prepare a homogeneous solution having a solid content of 60%.

  Subsequently, after adding the said electroconductive particle so that the filling rate of the electroconductive particle represented by the ratio which occupies for the total amount of solid content (electroconductive particle + resin + elastomer) may be 0.15 volume%, it is a centrifugal mixer. Was uniformly dispersed by stirring to prepare a film-like anisotropic conductive adhesive solution.

  The adhesive solution prepared above is applied onto a PET film subjected to a release treatment using a doctor knife, and dried and solidified at 60 ° C. for 30 minutes in a magnetic field having a magnetic flux density of 100 mT. A film-like anisotropic conductive adhesive having a thickness of 20 μm oriented in the magnetic field direction was prepared. The film-like anisotropic conductive adhesive was measured and evaluated for the total chlorine content, insulation stability, initial resistance, and connection reliability based on the above evaluation method. The results are shown in Table 1.

The above (a) to (c) are mixed at a mass ratio of a: b: c = 25: 25: 10, and a mixed solvent of propylene glycol monomethyl ether acetate (PMA) and butyl acetate (mixing ratio 90 / 10), and then mixed for 3 minutes using a centrifugal mixer to prepare a homogeneous solution with a solid content of 60%, and this epoxy resin solution is coated on a substrate and dried to form a film The total chlorine amount measured based on the above evaluation method was 680 ppm.
Also, (e) Asahi Kasei E-Materials Co., Ltd. NovaCure LSA-H0910 was coated on a substrate and dried, and the total chlorine content measured based on the above evaluation method was 85 ppm. It was.

No. 2-5:
Using curing agents with different chlorine contents, No. In the same manner as in No. 1, film-like anisotropic conductive adhesives having different total chlorine contents were produced. About the obtained film-like anisotropic conductive adhesive, based on the said evaluation method, it measured and evaluated about insulation, initial stage connection, and connection reliability. The results are shown in Table 1.
In addition, No. The curing agents 2-5 used in 2-5 are as follows.
Curing agent 2: Novacure LSA-H1004 (total chlorine content: 160 ppm)
Curing agent 3: NOVACURE HXA-3932HP (total chlorine content: 550 ppm)
Curing agent 4: Novacure HXA-3042HP (total chlorine content: 700 ppm)
Curing agent 5: NOVACURE HX-3088 (total chlorine content: 1300 ppm)

No. 6:
Ex. Except that the epoxy resin (c) was changed to Epicron 850LC manufactured by DIC Corporation. In the same manner as in No. 1, film-like anisotropic conductive adhesives having different total chlorine contents were produced. About the obtained film-like anisotropic conductive adhesive, based on the said evaluation method, it measured and evaluated about insulation, initial stage connection, and connection reliability. The results are shown in Table 1.
In addition, No. For the film obtained by applying and drying the epoxy resin solution used in 6 on the substrate, the total chlorine content measured based on the above evaluation method was 8300 ppm.

  The joined body 2 is a joined body obtained by curing under the curing condition 2 considered to be the most economical in the used film-like anisotropic conductive adhesive. No. 1 and No. 2, No. 3 and no. Although there was a result of reversal as in FIG. 4, as a whole, the larger the total amount of chlorine, the larger the initial resistance, and the tendency of poor connection reliability was recognized. The bonded body 1 is a bonded body obtained by curing under the curing condition 1 in which the film-like anisotropic conductive adhesive is sufficiently softened and melted to fill the gap between the adjacent electrodes. As the total chlorine content of the film-like anisotropic conductive adhesive increased, the insulation stability tended to decrease. In particular, when the total chlorine content was 600 ppm or more, there was a tendency for the insulation stability to decrease significantly.

  Further, even when the curing agent 1 having a small amount of total chlorine is used, an epoxy resin having a large amount of chlorine (1000 ppm or more in the epoxy resin) is used as the binder resin. The total chlorine content of the anisotropic conductive adhesive became 600 ppm or more (No. 6), and connection reliability and insulation stability were insufficient.

  From the above, regarding the film-like anisotropic conductive adhesive, it can be seen that the total chlorine content of the entire film affects the connection reliability and the insulation stability of the joined body. Therefore, by measuring and inspecting the total amount of chlorine at the stage of the film-like anisotropic conductive adhesive, it is possible to pick up what is highly likely not to satisfy connection reliability and insulation stability.

  If the film-like anisotropic conductive adhesive of the present invention is used, a bonded body having high connection reliability and insulation stability can be obtained. According to the inspection method of the present invention, a film-like anisotropic conductive adhesive that may not yield a joined body having satisfactory connection reliability and insulation stability is obtained. Since it can be efficiently sorted out at the manufacturing site and excluded from shipment, it is economical for both the manufacturer of the film-like anisotropic conductive adhesive and the user who performs the bonding.

Claims (5)

(A) epoxy resin; (B) conductive particles; and (C) a film-like anisotropic conductive adhesive comprising a microcapsule-type imidazole-based latent curing agent,
A film-like anisotropic conductive adhesive, characterized in that the amount of chlorine in a gas obtained by burning the film-like anisotropic conductive adhesive is less than 600 ppm. 2. The film-like anisotropic conductive adhesive according to claim 1, wherein the (A) epoxy resin is a mixture of a phenoxy resin, a liquid epoxy resin that is liquid at room temperature, and a solid epoxy resin that is solid at room temperature. 3. The film-like anisotropic conductive adhesive according to claim 1, wherein the total chlorine content contained in the (A) epoxy resin is 1000 ppm or less. The film-like anisotropic conductive adhesive according to any one of claims 1 to 3, wherein the total chlorine content of the (C) microcapsule type imidazole-based latent curing agent is 400 ppm or less. (A) epoxy resin; (B) conductive particles; and (C) a film-like anisotropic conductive adhesive containing a microcapsule type imidazole-based latent curing agent,
An inspection method comprising a step of burning a measurement sample obtained by pulverizing the film-like anisotropic conductive adhesive; and a step of determining whether or not the amount of chlorine contained in the obtained combustion gas is less than 600 ppm.

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