JP2011049185A - Anisotropic conductive film, and manufacturing method for connection structure using the same - Google Patents

Abstract

The present invention provides an anisotropic conductive film with excellent storage stability while realizing low-temperature curing by rapid curing, and further uses this anisotropic conductive film to produce a connection structure with high conduction reliability. A method for manufacturing a connection structure is provided.
An anisotropic conductive film 1 is formed by sequentially laminating a first resin layer 1A containing an oxetane compound and a second resin layer 1B containing a cationic polymerization initiator. In the anisotropic conductive film 1, at least one of the first resin layer 1A and the second resin layer 1B contains conductive particles, and the first resin layer 1A or the second resin layer 1B is a phosphine oxide. Contains compounds.
[Selection] Figure 1

Description

  The present invention relates to an anisotropic conductive film used when an electronic member such as a flexible printed wiring board or a semiconductor element is mounted on a wiring board such as a liquid crystal panel. Furthermore, the anisotropic conductive film is used. The present invention relates to a method for manufacturing a connection structure.

  The anisotropic conductive film is obtained by dispersing conductive particles in an insulating resin (adhesive component such as a thermoplastic material or a thermosetting material) that functions as an adhesive. For example, in the connection between the electronic component and the wiring board, an anisotropic conductive film is sandwiched between the bump of the electronic component and the electrode portion of the wiring board, and heated and pressed by a pressing operation. Thereby, electroconductive particle is crushed and electrical connection is achieved. In the portion where there is no bump, the conductive particles are kept dispersed in the insulating resin, and are kept electrically insulated. For this reason, electrical conduction is achieved only at the portion where the bump exists.

  In the development of anisotropic conductive films, research on properties of anisotropic conductive films such as adhesion reliability and conduction reliability has been promoted in various fields. For example, properties based on adhesive strength have already been improved by technological improvements. A considerable level has been reached. On the other hand, in terms of fast curability, storage stability, etc., insufficient points have been pointed out, and improving handling properties based on fast curability, storage stability, etc. has become a recent issue.

  In such a situation, for example, from the viewpoint of fast curability, selection of a component having a relatively high reactivity in an epoxy resin and selection of a component having a high activity as a curing agent are being considered (for example, Patent Documents 1 to 3).

  For example, Patent Document 1 discloses an adhesive composition containing an insulating resin, a photopolymerization initiator, and an oxetane compound, as well as an adhesive composition. An anisotropic conductive adhesive composition is disclosed which contains conductive particles in a product. Since the oxetane compound has high cationic curability, the adhesive composition containing the oxacene compound can greatly shorten the curing time.

  Further, for example, Patent Document 2 discloses an anisotropic conductive adhesive in which conductive particles are dispersed in a binder containing a thermosetting resin, wherein the binder contains silsesquioxane. An adhesive is disclosed. A polymer of silsesquioxane and thermosetting resin is characterized by high hydrophobicity and a function of preventing corrosion, and can provide an anisotropic conductive adhesive with high conduction reliability. It is.

  On the other hand, as an example of selecting a highly active component as a curing agent, for example, in Patent Document 3, in an anisotropic conductive film in which conductive particles are dispersed in an organic binder component, the organic binder component is a cationic polymerizable substance. An anisotropic conductive film containing a cation generator such as a sulfonium salt and a cation scavenger is disclosed. The anisotropic conductive film described in Patent Document 3 can be connected at a low temperature in a short time.

JP 2001-207150 A JP 2008-179682 A Japanese Patent No. 3589422

  By the way, when a technique using a thermosetting resin or a curing agent having a relatively high reactivity is employed as in the techniques described in Patent Documents 1 to 3, fast curing and low temperature curing are expected, but anisotropic. There exists a possibility that the storage stability of a conductive adhesive or an anisotropic conductive film may fall.

  Therefore, as a method for improving the storage stability, it is conceivable to separate the resin component and the curing agent component into separate layers and suppress the reaction between the resin component and the curing agent component before use. For example, the anisotropic conductive film has a two-layer structure, one containing a resin component and the other containing a curing agent component, and causing the resin component and the curing agent component to react during thermocompression bonding.

  However, even if the anisotropic conductive film has a two-layer structure, since the layer containing the resin component and the layer containing the curing agent component are in contact with each other, the reaction at the interface cannot be completely suppressed and is not always sufficient. There is a problem that it is not possible to obtain stable storage stability. Moreover, in the production of an anisotropic conductive film having a two-layer structure, due to the effects of heating, pressurization, solvent addition, etc. during laminating and coating operations to form a layer structure, both layers result The components are mixed, and there is a drawback that the entire layer reacts or a mixed layer (mixed region) made of the reaction product is formed.

  The present invention has been proposed for the purpose of solving the problems of the prior art described above, and by separating the resin component and the curing agent component into separate layers, rapid curing and low temperature curing can be achieved. An object of the present invention is to provide an anisotropic conductive film that can realize the high storage stability by suppressing the reaction at the interface between the two layers, and can solve the problem of forming a mixed layer during production. Moreover, it aims at providing the manufacturing method of the connection structure which can be connected in low temperature for a short time by using such an anisotropic conductive film, and can obtain a reliable conductive connection state. .

  The inventors of the present invention, by containing the oxetane compound and the cationic polymerization initiator in separate resin layers, prevent both from reacting at an early stage, and by incorporating a phosphine oxide compound in one resin layer. It has been found that it is possible to suppress the reaction at the interface of the resin layer and the mixing of both at the time of lamination.

  That is, in order to achieve the above-mentioned object, the anisotropic conductive film of the present invention is formed by laminating a first resin layer containing an oxetane compound and a second resin layer containing a cationic polymerization initiator. And at least one of the first resin layer and the second resin layer is an anisotropic conductive film containing conductive particles, wherein the first resin layer or the second resin layer is a phosphine oxide compound. It is characterized by containing.

  Moreover, the manufacturing method of the connection structure of the present invention is a method of manufacturing a connection structure in which an electrode of a wiring board and an electrode of an electronic member are connected via an anisotropic conductive film. It has a connection step of connecting the electrode of the wiring board and the electrode of the electronic member by placing the conductive film and the electronic member in order and performing thermal pressurization, and contains an oxetane compound as an anisotropic conductive film The first resin layer and the second resin layer containing the cationic polymerization initiator are laminated, and at least one of the first resin layer and the second resin layer contains conductive particles. The first resin layer or the second resin layer uses an anisotropic conductive film containing a phosphine oxide compound.

  The anisotropic conductive film of the present invention has a two-layer structure, contains an oxetane compound as a reaction main agent in the first resin layer, and contains a cationic polymerization initiator as a curing agent in the second resin layer. . Oxetane compounds have high reactivity, and when combined with a cationic polymerization initiator, fast curability is obtained and low temperature curing is also possible. On the other hand, the 1st resin layer containing an oxetane compound does not use a cationic polymerization initiator. By separating the oxetane compound as the main reaction agent and the cationic polymerization initiator as the curing agent into two layers (hereinafter simply referred to as “layer separation”), it is possible to prevent the oxetane compound from reacting at an early stage. It becomes.

  Furthermore, in the present invention, by blending a phosphine oxide compound into the first resin layer or the second resin layer, the interface between the first resin layer and the second resin layer, or both are laminated and mixed. The reaction between the oxetane compound and the cationic polymerization initiator is suppressed. Thereby, high storage stability can be realized in the entire anisotropic conductive film.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the anisotropic conductive film which has quick curing property, can be hardened | cured at low temperature for a short time, and has sufficient storage stability. Moreover, according to the manufacturing method of the connection structure of the present invention, it is possible to obtain a highly reliable conductive connection state by connection at a low temperature in a short time.

It is a principal part schematic sectional drawing which shows the structural example of an anisotropic conductive film. It is a schematic sectional drawing which shows the structural example of a connection structure.

  Hereinafter, an embodiment of a method for producing an anisotropic conductive film and a connection structure to which the present invention is applied (hereinafter referred to as “this embodiment”) will be described in detail with reference to the drawings.

  The anisotropic conductive film in the present embodiment is obtained by dispersing and blending conductive particles in an adhesive component, and has a two-layer structure in which a highly reactive resin (reactive agent) and a curing agent are separated into layers. . Thereby, the reaction main agent and the curing agent are prevented from reacting at an early stage. FIG. 1 is a schematic cross-sectional view of a main part of the anisotropic conductive film of the present embodiment. As shown in FIG. 1, the anisotropic conductive film 1 is formed by laminating a first resin layer 1A containing a reaction main agent and a second resin layer 1B containing a curing agent.

  The first resin layer 1A contains an oxetane compound as a reaction main agent. The oxetane compound is a compound having an oxetane ring represented by the formula (1), and is characteristically contained in the anisotropic conductive film 1 in order to increase the reactivity of the adhesive composition.

The number of oxetane rings in the oxetane compound is arbitrary, and may be one or plural. Examples of the oxetane compound having one oxetane ring include a compound represented by the formula (2). In Formula (2), R ¹ is a hydrogen atom or a lower alkyl group, and a methyl or ethyl group is particularly preferable. R ² and R ³ are, for example, lower alkyl groups, and those substituted with other elements include halogens having 1 to 4 carbon atoms such as chloromethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, etc. And a C2-C4 cyanoalkyl group such as 3-cyanopropyl. Here, R ² and R ³ may be the same or different. R ⁴ has an allyl group, an aryl group, an araallyl group having 7 to 10 carbon atoms, a linear or branched alkyl group having 1 to 18 carbon atoms, or a branch having a hydroxyl group having 1 to 10 carbon atoms. Or a good alkyl group. Examples of X include methylene and oxygen atoms.

Examples of the oxetane compound having two oxetane rings include a compound represented by the formula (3). In formula (3), R ⁵ and R ⁶ represent a hydrogen atom, a lower alkyl group or a substituted hydrocarbon group, and R ⁵ and R ⁶ may be the same or different. R ⁷ represents an oxygen atom or a divalent functional group represented by the formula (4). Here, examples of the substituted hydrocarbon group include halogenated alkyl groups having 1 to 4 carbon atoms such as chloromethyl, 3-chloropropyl and 3,3,3-trifluoropropyl, and carbon numbers such as 3-cyanopropyl. Examples thereof include 2 to 4 cyanoalkyl groups.

_{^{-O- (R 8 -O) k -}} (4)
In the formula (4), k is an integer of 1 to 5, and R ⁸ represents a hydrocarbon group which may have a linear or branched hydroxyl group having 2 to 12 carbon atoms, preferably ethylene, Propylene, benzenedimethyl and the like.

As a polyfunctional oxetane compound, the compound shown, for example in Formula (5) is mentioned. In Formula (5), R ⁹ is a hydrogen atom or an alkyl group which may have 1 to 6 carbon atoms, and R ¹⁰ is an alkylene group having 1 to 6 carbon atoms, a chain or branched poly ( M) is an m-valent group selected from the group consisting of an alkylene group, a xylylene group, etc., Z is an ether group, a thioether group, a methylene group, an ester group or the like, and m is 2, 3 or 4.

  Specific examples of the oxetane compound include, for example, xylylene oxetane (XDO) represented by formula (6), 3-ethyl-3- (hydroxymethyl) oxetane (EOXA) represented by formula (7), and formula (8). 3-ethyl-3- (hexyloxymethyl) oxetane (HOX), 3-ethyl-3- (phenoxymethyl) oxetane (PHO) represented by formula (9), bis {[1-ethyl ( 3-oxetanyl)] methyl} ether (DOX) and the like. Among them, bifunctional XDO and DOX are particularly preferable from the viewpoint of high reactivity. Furthermore, XDO is most preferable from the viewpoint that the reaction suppressing effect with the cationic polymerization initiator based on the phosphine oxide compound described later is the highest.

  1 A of 1st resin layers may contain thermosetting resin components other than an oxetane compound, in order to provide film formability and to obtain mechanical bond strength. Examples of the thermosetting resin component include various epoxy resins, thermosetting resins such as epoxy group-containing (meth) acrylate, urethane-modified (meth) acrylate, and the like. For example, examples of the epoxy resin include bisphenol A (BPA) type epoxy resin, bisphenol F (BPF) epoxy resin, and novolak type epoxy resin. Among these, bisphenol A (BPA) type epoxy resin and bisphenol F (BPF) epoxy resin are suitable, and optimum fluidity can be obtained by using these. In addition, when using as a constituent material of an anisotropic conductive film, a thermosetting resin component is a non-hardened state (liquid state).

  Furthermore, the first resin layer 1A can be blended with a thermoplastic resin from the viewpoint of film formability. In this case, any thermoplastic resin can be used as the thermoplastic resin. For example, when an epoxy resin is selected as the thermosetting resin component of the second resin layer 1B, a thermoplastic resin that is compatible with the epoxy resin without being separated and can exhibit properties as a film is selected and used. Is preferred. Examples of the thermoplastic resin include phenoxy resin.

  In the first resin layer 1A, the mixing ratio of each component is arbitrary. For example, the ratio of the oxetane compound and the thermoplastic resin (oxetane compound: thermoplastic resin) is 20 parts by weight: 80 parts by weight to 80 parts by weight: 20 parts by weight is preferable. The ratio of the thermosetting resin is preferably 0 to 20 parts by weight with respect to 100 parts by weight of the total amount of the oxetane compound and the thermoplastic resin.

  The thickness of the first resin layer 1A may be set in consideration of the thickness of the second resin layer 1B described later, but is usually set to 10 μm to 25 μm.

  On the other hand, the second resin layer 1B needs to contain a cationic polymerization initiator that is a curing agent. The cationic polymerization initiator is activated by the application of light or heat to generate an acid component, and acts to induce polymerization of a cationic polymerizable group in the composition. In the anisotropic conductive film 1, it is necessary to induce polymerization of the octacene compound contained in the first resin layer 1A. For this reason, for example, an onium salt that is activated by irradiation with light and can induce ring-opening of a ring-opening polymerizable group of the oxetane compound is suitable as a cationic polymerization initiator having photolatency.

  Examples of the onium salts include diazonium salts, sulfonium salts, iodonium salts, and the like. For example, trade name Optmer SP-150 (Asahi Denka Kogyo Co., Ltd.), trade name Optmer SP-170 (Asahi Denka Kogyo Co., Ltd.), trade name UVE-1014 (General Electronics Co., Ltd.), trade name Road Sill 2074 ( It is possible to use commercial products such as Rhodia Co., Ltd.) and trade name CD-1012 (Sartomer Co., Ltd.).

  In addition, a cationic polymerization initiator having thermal potential can also be used. Cationic polymerization initiators having thermal potential are those that are activated by heating and induce ring opening of the ring-opening polymerizable group of the oxetane compound, such as quaternary ammonium salts, phosphonium salts, sulfoniums. Examples thereof include various onium salts such as salts. As such onium salts, for example, trade name Adeka Opton CP-66 and trade name Adeka Opton CP-77 (Asahi Denka Kogyo Co., Ltd.), trade name Sun Aid SI-60L, trade name Sun Aid SI-80L, trade name Sun Aid SI Commercial products such as −100 L (manufactured by Sanshin Chemical Industry Co., Ltd.) and CI series (manufactured by Nippon Soda Co., Ltd.) can be used.

  In addition, the second resin layer 1B may contain a thermoplastic resin or a thermosetting resin in order to impart film forming properties. The first resin layer 1A contains an oxetane compound as a highly reactive thermosetting resin, but the second resin layer 1B contains a thermosetting resin that is less reactive than the oxetane compound, It is preferable to allow the entire anisotropic conductive film 1 to function as a thermosetting resin adhesive.

  As the thermosetting resin of the second resin layer 1B, the same resin as the thermosetting resin other than the oxetane compound in the first resin layer 1A can be used, and various epoxy resins and epoxy group-containing (meth) acrylates can be used. And thermosetting resins such as urethane-modified (meth) acrylate. Among these, an epoxy resin having a lower reactivity than the oxetane compound is preferable.

  Although any thermoplastic resin can be used as the thermoplastic resin, for example, when an epoxy resin is selected as the thermosetting resin component in at least one of the first resin layer 1A and the second resin layer 1B, It is preferable to select and use a phenoxy resin that is compatible with the epoxy resin without separation and can exhibit properties as a film.

  In the second resin layer 1B, the mixing of each component is arbitrary, but the mixing ratio of the cationic polymerization initiator, the thermoplastic resin, and the thermosetting resin is 1 to 10 parts by weight of the cationic polymerization initiator, It is preferable to use 20 to 80 parts by weight of the thermoplastic resin and 80 to 20 parts by weight of the thermosetting resin.

  The thickness of the second resin layer 1B may be set in consideration of the thickness of the first resin layer 1A, and is usually 10 μm to 25 μm.

  At least one of the first resin layer 1A and the second resin layer 1B contains conductive particles dispersed therein. Examples of conductive particles to be included in each resin layer include particles of various metals and metal alloys such as nickel, iron, copper, aluminum, tin, lead, chromium, cobalt, silver, and gold, metal oxides, carbon, graphite, The surface of particles such as glass, ceramic, plastic, etc. coated with metal, or the surface of these particles further coated with an insulating thin film can be used. When using a resin particle surface coated with metal, the resin particles include, for example, epoxy resin, phenol resin, acrylic resin, acrylonitrile / styrene (AS) resin, benzoguanamine resin, divinylbenzene resin, styrene resin, etc. Particles can be mentioned.

  In addition, it is preferable that at least one of the first resin layer 1A and the second resin layer 1B contains an inorganic filler as another additive composition. Examples of the inorganic filler include silica, talc, titanium oxide, calcium carbonate, magnesium oxide and the like. By controlling the content of the inorganic filler, the fluidity can be controlled and the particle capture rate can be improved.

  In the anisotropic conductive film 1, the oxetane compound is contained in the first resin layer 1A, and the cationic polymerization initiator is contained in the second resin layer 1B to separate the layers. This ensures fast curability and prevents early reaction between the oxetane compound and the cationic polymerization initiator. Here, since the first resin layer 1A and the second resin layer 1B are in direct contact with each other, it is necessary to suppress the reaction between the oxetane compound and the cationic polymerization initiator even at the interface.

  In the anisotropic conductive film 1, the phosphine oxide compound is contained in the first resin layer 1A or the second resin layer 1B to suppress the reaction between the oxetane compound and the cationic polymerization initiator. Due to the effect of the phosphine oxide compound, even at the interface between the first resin layer 1A and the second resin layer 1B or in the region where the first resin layer 1A and the second resin layer 1B are laminated and mixed, The reaction with the cationic polymerization initiator is suppressed, and high storage stability can be realized in the entire anisotropic conductive film 1.

Examples of the phosphine oxide compound include a compound represented by the formula (11). In the formula (11), R ^{11 to} R ¹³ each represent the same or different linear or branched hydrocarbon group, aromatic group or the like. Specifically, an alkyl group having 1 to 10 carbon atoms, or an alkyl group having 1 to 10 carbon atoms having a hydroxyl group, a fluorine atom, a chlorine atom, or a bromine atom, an alkenyl group having 4 to 10 carbon atoms, a phenyl group, A phenyl group having a halogen atom such as a fluorine atom, a chlorine atom, or a bromine atom, an araalkyl group, and the like, and these groups may have a branch.

Specifically, tributylphosphine oxide in which R ^{11 to} R ¹³ in formula (11) are all butyl groups, triphenylphosphine oxide that is phenyl groups, and tri (3-hydroxypropyl) phosphine oxide that is 3-hydroxypropyl group. And n-butyl-bis (3-hydroxypropyl) phosphine oxide composed of a butyl group and a 3-hydroxypropyl group.

  The phosphine oxide compound can obtain the effect even if it is contained in either the first resin layer 1A or the second resin layer 1B, but by containing it in the first resin layer 1A containing the oxetane compound, It has been experimentally confirmed that it is more effective. In addition, when the phosphine oxide compound is contained in both the first resin layer 1A and the second resin layer 1B, the reactivity of the anisotropic conductive film 1 as a whole is lowered, which is not preferable.

  The addition amount of the phosphine oxide compound may be set in consideration of the reaction suppressing effect and the reactivity of the entire anisotropic conductive film at the time of thermocompression bonding. Either the first resin layer 1A or the second resin layer 1B may be set. Also when adding, it is preferable to set it as 0.005 mass%-1.0 mass%, and it is especially preferable to set it as 0.001 mass%-0.1 mass%. If the addition amount of the phosphine oxide compound is less than 0.005% by mass, the reaction suppressing effect may not be sufficiently obtained. On the other hand, if it exceeds 1.0% by mass, the reaction during thermocompression bonding does not proceed smoothly, and it may be difficult to obtain fast curability.

  Next, the manufacturing method of the anisotropic conductive film 1 provided with such a structure is demonstrated. First, a composition for forming each of the first resin layer 1A and the second resin layer 1B is dissolved in an organic solvent such as toluene and methyl ethyl ketone to prepare first and second resin composition solutions. Then, the first and second resin composition solutions are applied on the first and second release films, respectively, using an application device such as a comma coater, a knife coater, or a gravure coater. Then, the first resin layer 1A is formed on the first release film by volatilizing the organic solvent in the first and second resin composition solutions, and the second resin is formed on the second release film. Layer 1B is formed. Next, 1 A of 1st resin layers and 2nd resin layer 1B are piled up, and it heats to about 70 to 100 degreeC as needed, and laminates and integrates them. Thereby, the anisotropic conductive film 1 in which the first resin layer 1A and the second resin layer 1B are sequentially laminated is manufactured. Thus, the anisotropic conductive film 1 is provided as a film laminated body by being formed on a peeling film. The second resin layer 1B is laminated on the first resin layer 1A by applying and drying the composition of the second resin layer 1B on the formed first resin layer 1A. The anisotropic conductive film 1 may be manufactured.

  In the composition solution for forming the first resin layer 1A and the second resin layer 1B, the boiling point of toluene, which is an organic solvent, is around 120 ° C. Here, since the oxetane compound and the cationic polymerization initiator are contained in separate resin layers, the reaction is promoted in each resin layer even when heated in a drying furnace or the like to volatilize the organic solvent. Absent. Moreover, even if it heats after laminating | stacking 2nd resin layer 1B on 1 A of 1st resin layers, it is the interface of 1st resin layer 1A and 2nd resin layer 1B by the effect | action of a phosphine oxide compound. The reaction is not accelerated.

  Next, the manufacturing method of the connection structure using the anisotropic conductive film 1 in this Embodiment is demonstrated. The connection structure manufacturing method according to the present embodiment performs anisotropic conduction between an electronic component such as an IC chip or an electronic member such as a flexible printed wiring board and a wiring board such as a rigid wiring board (rigid board) or a liquid crystal panel. It is electrically and mechanically connected and fixed via the film 1.

  Here, an example in which an electrode (terminal part) of a flexible printed wiring board and an electrode (terminal part) of a rigid wiring board are connected will be described.

  First, a film laminated body is arrange | positioned so that the anisotropic conductive film 1 may be laminated | stacked on the predetermined position on a rigid wiring board, and the peeling film in a film laminated body is peeled off (1st arrangement | positioning process). Then, temporary crimping | bonding with a rigid wiring board and the anisotropic conductive film 1 is performed (temporary crimping process). In the temporary press-bonding process, the thermosetting resin component contained in the anisotropic conductive film 1 is heated at a temperature of about 70 ° C. to 100 ° C. while being slightly pressed from the upper surface of the anisotropic conductive film 1 by the heat and pressure head. To do. Thereby, the thermoplastic resin component contained in the anisotropic conductive film 1 exhibits fluidity, and the anisotropic conductive film 1 is positioned and fixed on the rigid wiring board by the adhesive force of the thermoplastic resin component.

  After the temporary press-bonding step, the alignment state of the anisotropic conductive film 1 is confirmed, and if there is no misalignment or the like, the electronic member is placed at a predetermined position on the anisotropic conductive film 1 (first 2 placement step). Thereafter, heating is performed while applying pressure by pressing a thermo-pressurizing head from above the electronic member (main pressure bonding step). The heating temperature in the main pressure bonding is set to a temperature equal to or higher than the curing temperature of the thermosetting resin component contained in the anisotropic conductive film 1. Moreover, the pressure in this press-fit is set to such a pressure that the conductive particles contained in the anisotropic conductive film 1 are crushed. The temperature and pressure at the time of the main pressure bonding are, for example, a temperature of about 120 ° C. to 150 ° C. and a pressure of about 3 MPa to 12 MPa. Thereby, curing at a low temperature and in a short time is possible.

  The conductive particles contained in the anisotropic conductive film 1 are crushed at the portions where the electrode patterns face each other by the thermocompression treatment of the main pressure bonding, and electrical connection (conduction) is achieved. By such a method, a connection structure formed by connecting an electrode of a rigid wiring board and an electrode of a flexible printed wiring board is manufactured.

  In addition, after the temporary press-bonding step, the alignment state of the anisotropic conductive film 1 is confirmed, and when there is a problem such as misalignment, the anisotropic conductive film 1 is peeled off and the first placement step A repair process for returning to (1) may be performed (repair process).

  FIG. 2 is a schematic cross-sectional view illustrating a configuration example of a connection structure of a wiring board and an electronic member. The connection structure is disposed so that the anisotropic conductive film 1 is interposed between the wiring board 2 and the electronic member 3 so that the electrode (conductor) pattern of the wiring board 2 and the electrode pattern of the electronic member 3 face each other. Has been. Thereby, the wiring board 2 and the electronic member 3 are aligned based on the formation position of a corresponding electrode. The conductive particles contained in the anisotropic conductive film 1 are crushed at the portions where the electrode patterns face each other by being heated and pressurized at a temperature equal to or higher than the curing temperature of the thermosetting resin component from the electronic member 3 side. Thus, electrical connection (conduction) is achieved. At the same time, the oxetane compound contained in the first resin layer 1A of the anisotropic conductive film 1 and the cationic polymerization initiator contained in the second resin layer 1B are reacted and cured, and the wiring board 2 and the electronic member 3 The mechanical connection is also achieved.

  Any one of the first resin layer 1A and the second resin layer 1B of the anisotropic conductive film 1 may be arranged on the wiring board 2 side or the electronic member 3 side, When the thermocompression head is operated from the electronic member 3 side during thermocompression bonding, the second resin layer 1B having low reactivity is disposed so as to face the electronic member 3, and heat application by the thermocompression head is performed. It is preferable to perform pressure work. That is, heat pressing is performed by a heat pressing head from the surface opposite to the surface in contact with the first resin layer 1A of the second resin layer 1B. Thereby, it is possible to accelerate the curing reaction and further shorten the curing time.

  Thus, the anisotropic conductive film 1 in the present embodiment has fast curability, can be cured at a low temperature for a short time, and has sufficient storage stability. Moreover, it is possible to manufacture a connection structure with high conduction reliability by using the anisotropic conductive film 1.

  As mentioned above, although the anisotropic conductive film 1 in this Embodiment and the manufacturing method of a connection structure have been demonstrated, it cannot be overemphasized that this invention is not what is limited to the above-mentioned embodiment, and deviates from the summary of this invention. Various changes are possible without departing from the scope.

  In the manufacturing method of the above-mentioned connection structure, after the anisotropic conductive film 1 is disposed at a predetermined position on the wiring board, temporary bonding is performed. However, the connection structure may be manufactured without temporarily bonding the wiring board and the anisotropic conductive film 1. That is, after the wiring board, the anisotropic conductive film 1 and the electronic member are sequentially stacked so that the electrode pattern of the wiring board and the electrode pattern of the electronic member face each other, the main pressure bonding is performed without performing the temporary pressure bonding. Thus, a connection structure may be obtained.

  Next, specific examples of the present invention will be described based on experimental results.

<Production of anisotropic conductive film>
The following materials are blended in the proportions shown in [Table 1] (the numerical values in [Table 1] are parts by weight), and resin layer A (oxetane layer), resin layer B (oxetane layer), resin layer C (cured) Agent layer) and resin layer D (curing agent layer) were obtained.
・ Phenoxy resin: Bisphenol A type phenoxy resin (manufactured by Toto Kasei Co., Ltd., YP-50)
Oxetane compound: Xylylene oxetane resin (XDO, manufactured by Toagosei Co., Ltd.)
Epoxy resin: BPA type epoxy resin (YL980, manufactured by Japan Epoxy Resin Co., Ltd.)
-Phosphine oxide compound: Triphenylphosphine oxide (manufactured by Aldrich)
Silane coupling agent: Epoxy silane coupling agent (Momentive Performance Materials, A-187)
Cationic polymerization initiator: antimony cationic curing agent (manufactured by Sanshin Chemical Industry Co., Ltd., SI-60L)
Conductive particles: Resin core Au plated particles (Sekisui Chemical Co., Ltd., AUL704)

・ Resin layer A (oxetane layer)
A resin composition comprising 60 parts by weight of a phenoxy resin, 37.9 parts by weight of an oxetane compound, 0.1 part by weight of a phosphine oxide compound, 2 parts by weight of a silane coupling agent, and 14 parts by weight of conductive particles, did. Then, the resin composition was dissolved in a mixed solvent of toluene / ethyl acetate (1: 1 by weight), and then uniformly mixed with a mixer to prepare a composition solution. The obtained composition solution was applied onto a peeled polyethylene terephthalate film and dried at 70 ° C. for 5 minutes to obtain a resin layer A having a thickness of 10 μm.

・ Resin layer B (oxetane layer)
A resin composition comprising 60 parts by weight of a phenoxy resin, 37.99 parts by weight of an oxetane compound, 0.01 parts by weight of a phosphine oxide compound, 2 parts by weight of a silane coupling agent, and 14 parts by weight of conductive particles, Except for the above, a resin layer B was obtained in the same manner as in the production process of the resin layer A.

・ Resin layer C (curing agent layer)
A resin composition comprising 60 parts by weight of a phenoxy resin, 34.8 parts by weight of an epoxy resin, 2 parts by weight of a silane coupling agent, 3.2 parts by weight of a cationic polymerization initiator, and 14 parts by weight of conductive particles. Except for the above, a resin layer C was obtained in the same manner as in the resin layer A fabrication process.

・ Resin layer D (hardener layer)
A resin composition comprising 60 parts by weight of a phenoxy resin, 34.8 parts by weight of an oxetane compound, 2 parts by weight of a silane coupling agent, 3.2 parts by weight of a cationic polymerization initiator, and 14 parts by weight of conductive particles. A resin layer D was obtained in the same manner as the production process of the resin layer A except that.

  Next, the produced resin layers A to D were combined as shown in [Table 2] to produce an anisotropic conductive film having a thickness of 20 μm in which the second resin layer was laminated on the first resin layer (implementation). Examples 1, 2 and Comparative Examples 1-3).

Example 1
A resin layer C as a second resin layer was laminated on the resin layer A as a first resin layer to produce a two-layer anisotropic conductive film.

(Example 2)
A resin layer C as a second resin layer was laminated on a resin layer B as a first resin layer to produce a two-layer anisotropic conductive film.

(Comparative Example 1)
A resin layer D as a second resin layer was laminated on the resin layer D as a first resin layer to produce a two-layer anisotropic conductive film. That is, in Comparative Example 1, an anisotropic conductive film was constituted only by the resin layer D.

(Comparative Example 2)
A two-layer anisotropic conductive film was produced by laminating a resin layer D as a second resin layer on a resin layer A as a first resin layer.

(Comparative Example 3)
A resin layer D as the second resin layer was laminated on the resin layer B as the first resin layer to produce a two-layer anisotropic conductive film.

<Life test>
About the produced anisotropic conductive film (Example 1, 2 and Comparative Examples 1-3), the life test was done and the storage stability was investigated. In the life test, the anisotropic conductive films of Examples 1 and 2 and Comparative Examples 1 to 3 were allowed to stand at 55 ° C. for 24 hours, the reaction rate (%) was calculated by differential scanning calorimetry (DSC), and the storage stability. Evaluated. The results are shown in [Table 3]. In [Table 3], ◯ indicates that the reaction rate is low and the storage stability is good, Δ indicates that the reaction rate is slightly high and storage stability is slightly insufficient, and × indicates that the reaction rate is very high and storage stability is poor. Show that each is enough.

  As is clear from [Table 3], in the anisotropic conductive films of Examples 1 and 2, in which the oxetane compound and the cationic polymerization initiator were separated into layers, and the phosphine oxide compound was added to the resin layer containing the oxetane compound, The reaction rate in the life test was low, and good storage stability was realized. On the other hand, in the anisotropic conductive films of Comparative Examples 1 to 3 in which the oxetane compound and the cationic polymerization initiator are included in one layer, the reaction rate in the life test is high, and the storage stability may be insufficient. confirmed.

<Connection test>
Via each of the produced anisotropic conductive films (Examples 1 and 2 and Comparative Examples 1 to 3), the flexible printed wiring board and the rigid wiring board (substrate) produced for evaluation were mounted by FOB (Film On Board). Connected. In the connection structure after connection, the conduction resistance value (initial and after aging) and the adhesive strength were comparatively evaluated. The evaluation conditions are as follows.
Flexible printed wiring board: 3 layer type (polyimide substrate 22 μm thickness / Cu wiring 18 μm thickness / surface gold plating), 0.2 mm pitch (L / S = 1/1)
Rigid wiring board: (Glass epoxy substrate FR-4 1.1 mm thickness / Cu wiring 35 μm thickness / surface gold plating), 0.2 mm pitch (L / S = 1/1)
-Connection conditions: heating temperature 140 ° C. (15 seconds), pressure 3 MPa

<Measurement>
[Conduction resistance (initial)]
In the connection structure after FOB mounting, the initial resistance value was measured by a four-terminal method using a digital multimeter. The average value of connection resistance was less than 50 mΩ, and the value of 50 mΩ or more was rated as x. The results for the connection structures using the anisotropic conductive films of Examples 1 and 2 and Comparative Examples 1 to 3 are shown in [Table 4].

[Conduction resistance (after aging)]
After the connection structure after mounting the FOB is left for 500 hours under 85 ° C. and 85% RH (after aging), the resistance value of the connection structure is measured, and the ratio with the initial conduction resistance value is less than twice. A case where the conduction resistance value increased by more than 2 times was evaluated as x. The results for the connection structures using the anisotropic conductive films of Examples 1 and 2 and Comparative Examples 1 to 3 are shown in [Table 4].

[Adhesive strength]
The peel strength (N / cm) when the rigid wiring board is fixed and the flexible printed wiring board is peeled off at a speed of 50 mm / min in the 90 ° direction is measured as the adhesive strength (N / cm) of the anisotropic conductive film. did. The results for the connection structures using the anisotropic conductive films of Examples 1 and 2 and Comparative Examples 1 to 3 are shown in [Table 4].

  As is clear from [Table 4], in the anisotropic conductive films of Examples 1 and 2, high adhesive strength was obtained even at low temperature connection. In addition, the conduction resistance was low both in the initial stage and after aging, and the conduction reliability was good. This is presumably because the oxetane compound as the main reaction agent and the cationic polymerization initiator as the curing agent were contained in separate layers. Thus, in the anisotropic conductive films of Examples 1 and 2, it was confirmed that the basic performances such as adhesion reliability and conduction reliability of the anisotropic conductive film in the connection structure were sufficient.

DESCRIPTION OF SYMBOLS 1 Anisotropic conductive film, 1A 1st resin layer, 1B 2nd resin layer, 2 Wiring board, 3 Electronic member

Claims (7)

A first resin layer containing an oxetane compound;
A second resin layer containing a cationic polymerization initiator is laminated,
At least one of the first resin layer and the second resin layer is an anisotropic conductive film containing conductive particles,
The anisotropic conductive film, wherein the first resin layer or the second resin layer contains a phosphine oxide compound.   The anisotropic conductive film according to claim 1, wherein the first resin layer contains the phosphine oxide compound.   The anisotropic conductive film according to claim 1 or 2, wherein the first resin layer contains a thermoplastic resin and a thermosetting resin other than an oxetane compound.   The anisotropic conductive film according to claim 1, wherein the second resin layer contains a thermoplastic resin and a thermosetting resin.   The anisotropic conductive film according to claim 4, wherein the second resin layer contains an epoxy resin as the thermosetting resin. In the manufacturing method of the connection structure formed by connecting the electrode of the wiring board and the electrode of the electronic member through the anisotropic conductive film,
Having a connection step of connecting the electrode of the wiring board and the electrode of the electronic member by placing the wiring board, the anisotropic conductive film and the electronic member one after another and performing thermal pressing;
As the anisotropic conductive film, a first resin layer containing an oxetane compound and a second resin layer containing a cationic polymerization initiator are laminated, and the first resin layer and the second resin layer are laminated. At least one of the resin layers contains conductive particles, and the first resin layer or the second resin layer uses an anisotropic conductive film containing a phosphine oxide compound. Body manufacturing method.   7. The connection according to claim 6, wherein, in the connecting step, the thermal pressurization is performed by a thermal pressurization head from a surface opposite to a surface in contact with the first resin layer of the second resin layer. Manufacturing method of structure.

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