JP2015149131A - Anisotropic conductive film and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anisotropic conductive film having a multilayer structure including conductive particles arranged in a single layer and capable of achieving good conduction reliability, good insulating properties, and a good mounting conductive particle capture ratio.SOLUTION: An anisotropic conductive film has a first connection layer and a second connection layer formed on one surface of the first connection layer. The first connection layer is a photo-polymerization resin layer, and the second connection layer is a thermal-cationic or photo-cationic polymerizable resin layer, a thermal-anionic or photo-anionic polymerizable resin layer, or a thermal-radical or photo-radical polymerizable resin layer. Conductive particles for anisotropic conductive connection are arranged on a surface on the second connection layer side of the first connection layer so that an embedding ratio to the first connection layer becomes not less than 1% and not more than 20%.

Description

  The present invention relates to an anisotropic conductive film and a method for producing the same.

  Anisotropic conductive films are widely used for mounting electronic components such as IC chips. Recently, from the viewpoint of application to high mounting density, improvement of conduction reliability and insulation, improvement of mounting conductive particle capture rate For the purpose of reducing manufacturing costs, etc., a two-layer anisotropic conductive film in which conductive particles for anisotropic conductive connection are arranged in a single layer on an insulating adhesive layer has been proposed (Patent Document 1). .

  In this anisotropic conductive film having a two-layer structure, conductive particles are arranged uniformly at predetermined intervals by biaxially stretching the transfer layer after conductive particles are arranged in a single layer and closely packed in the transfer layer. After forming a transfer layer, the conductive particles on the transfer layer are transferred to an insulating resin layer containing a thermosetting resin and a polymerization initiator, and the transferred conductive particles contain a thermosetting resin. However, it is manufactured by laminating another insulating resin layer that does not contain a polymerization initiator (Patent Document 1).

Japanese Patent No. 4778938

  However, since the anisotropic conductive film having a two-layer structure in Patent Document 1 uses an insulating resin layer that does not contain a polymerization initiator, the conductive particles are evenly arranged at predetermined intervals in a single layer. Nevertheless, a relatively large resin flow is likely to occur in the insulating resin layer that does not contain the polymerization initiator due to heating during anisotropic conductive connection, and the conductive particles also easily flow along the flow. For this reason, problems such as a decrease in the mounting conductive particle capture rate, the occurrence of short circuits, and a decrease in insulation have occurred. There has also been a demand for further improving the adhesive strength.

  The object of the present invention is to solve the above-mentioned problems of the prior art, in a multilayer structure anisotropic conductive film having conductive particles arranged in a single layer, good conduction reliability, good insulation. And good mounting conductive particle capture rate.

  The present inventors fixed or temporarily fixed conductive particles by irradiating with ultraviolet rays after arranging the conductive particles in a photopolymerizable resin layer in a single layer so as to fill in a specific ratio. Or the anisotropic conductive film obtained by laminating | stacking a heat | fever or a photocation, anion, or a radically polymerizable resin layer on the electrically fixed electrically conductive particle is the structure which can achieve the objective of the above-mentioned this invention. As a result, the present invention has been completed.

That is, the present invention is an anisotropic conductive film having a first connection layer and a second connection layer formed on one side thereof,
The first connection layer is a photopolymerization resin layer;
The second connection layer is a heat or photocation, anion or radical polymerizable resin layer;
Conductive particles for anisotropic conductive connection are arranged in a single layer on the second connection layer side surface of the first connection layer, and the embedding rate of the conductive particles in the first connection layer is 1% or more and 20% or less. An anisotropic conductive film is provided. Here, the embedding rate means the degree to which the conductive particles are buried in the first connection layer, and the depth Lb of the conductive particles embedded in the first connection layer with respect to the particle diameter La of the conductive particles. The ratio (embedding rate) can be defined by the formula of “embedding rate (%) = (Lb / La) × 100”.

  The second connection layer is preferably a thermopolymerizable resin layer using a thermal polymerization initiator that starts a polymerization reaction by heating, but photopolymerization using a photopolymerization initiator that starts a polymerization reaction by light. May be a conductive resin layer. A thermal / photopolymerizable resin layer in which a thermal polymerization initiator and a photopolymerization initiator are used in combination may be used. Here, the second connection layer may be limited to a thermopolymerizable resin layer using a thermal polymerization initiator in production.

  The anisotropic conductive film of the present invention has a third connection layer having substantially the same configuration as the second connection layer on the other surface of the first connection layer for the purpose of preventing warpage of the joined body such as stress relaxation. It may be. That is, you may have the 3rd connection layer which consists of a heat | fever or a photocation, an anion, or a radically polymerizable resin layer in the other surface of a 1st connection layer.

  The third connection layer is preferably a thermopolymerizable resin layer using a thermal polymerization initiator that initiates a polymerization reaction by heating, but photopolymerization using a photopolymerization initiator that initiates a polymerization reaction by light. May be a conductive resin layer. A thermal / photopolymerizable resin layer in which a thermal polymerization initiator and a photopolymerization initiator are used in combination may be used. Here, the third connection layer may be limited to a thermopolymerizable resin layer using a thermal polymerization initiator in production.

  Moreover, this invention is a manufacturing method of the above-mentioned anisotropic conductive film, Comprising: The following processes (A)-(C) which form a 1st connection layer by one-step photopolymerization reaction, or a 1st connection layer The manufacturing method which has process (AA)-(DD) mentioned later which forms is formed by a two-stage photopolymerization reaction is provided.

(When the first connection layer is formed by a one-step photopolymerization reaction)
Process (A)
Arranging the conductive particles in the photopolymerizable resin layer in a single layer so that the embedding rate of the conductive particles in the first connection layer is 1% or more and 20% or less;
Process (B)
A step of forming a first connection layer in which conductive particles are fixed on the surface by irradiating the photopolymerizable resin layer in which the conductive particles are arranged by irradiating with ultraviolet rays; and step (C)
The process of forming the 2nd connection layer which consists of a heat | fever or a photocation, an anion, or a radically polymerizable resin layer in the electrically conductive particle side surface of a 1st connection layer.

(When the first connection layer is formed by a two-step photopolymerization reaction)
Process (AA)
Arranging the conductive particles in the photopolymerizable resin layer in a single layer so that the embedding rate of the conductive particles in the first connection layer is 1% or more and 20% or less;
Process (BB)
A step of irradiating the photopolymerizable resin layer in which the conductive particles are arranged with each other by irradiating with ultraviolet light to form a temporary first connection layer in which the conductive particles are temporarily fixed;
Process (CC)
Forming a second connection layer comprising a thermal cation, anion, or radical polymerizable resin layer on the surface of the temporary first connection layer on the conductive particle side; and step (DD)
A step of forming a first connection layer by subjecting the temporary first connection layer to a photopolymerization reaction by irradiating ultraviolet rays from the side opposite to the second connection layer, and finally curing the temporary first connection layer.

  The initiator used in forming the second connection layer in the step (CC) is limited to the thermal polymerization initiator in terms of product life as an anisotropic conductive film, connection and stability of the connection structure. This is to prevent adverse effects from occurring. That is, in the case where the first connection layer is irradiated with ultraviolet rays in two stages, the second connection layer may be limited to a thermosetting curable one due to restrictions on the process. In addition, when performing two-step irradiation continuously, since it can form by the process substantially the same as one step | paragraph, the equivalent effect can be anticipated.

  Moreover, this invention is a manufacturing method of the anisotropic conductive film which has the 3rd connection layer of the structure similar to a 2nd connection layer in the other surface of a 1st connection layer, Comprising: The above process (A ) To (C), after the step (C), the production method having the following step (Z), or after the step (DD) in addition to the above steps (AA) to (DD), The manufacturing method which has the following processes (Z) is provided.

Step (Z)
The process of forming the 3rd connection layer which consists of a heat | fever or a photocation, an anion, or a radically polymerizable resin layer in the surface opposite to the electroconductive particle side of a 1st connection layer.

  Furthermore, this invention is a manufacturing method of the anisotropic conductive film which has the 3rd connection layer of the structure substantially the same as the 2nd connection layer on the other surface of the 1st connection layer, Comprising: A manufacturing method having the following step (a) prior to step (A) in addition to A) to (C), or the following steps prior to step (AA) in addition to the above steps (AA) to (DD) The manufacturing method which has a process (a) is provided.

Step (a)
A step of forming a third connection layer comprising a heat or photocation, anion or radical polymerizable resin layer on one surface of the photopolymerizable resin layer.

  In addition, in the process (A) or process (AA) of the manufacturing method which has this process (a), the embedding rate of the electroconductive particle with respect to the other surface of a photopolymerizable resin layer and the 1st connection layer is 1. What is necessary is just to arrange by a single layer so that it may become 20% or less%.

  In the case where the third connection layer is provided in such a process, it is preferable that the polymerization initiator is limited to a thermal reaction for the reasons described above. However, if the second and third connection layers containing the photopolymerization initiator are provided by a method that does not adversely affect the product life and connection after the first connection layer is provided, the photopolymerization initiator containing the photopolymerization initiator can be obtained. There is no particular limitation on the production of the anisotropic conductive film along the gist.

  An embodiment in which either the second connection layer or the third connection layer of the present invention functions as a tack layer is also included in the present invention.

  In addition, the present invention provides a connection structure in which the first electronic component is anisotropically conductively connected to the second electronic component using the anisotropic conductive film described above.

  The anisotropic conductive film of the present invention has a first connection layer made of a photopolymerization resin layer and a second connection layer made of a heat or photocation, anion or radical polymerizable resin layer formed on one surface thereof. Furthermore, the embedding rate of the conductive particles with respect to the first connection layer of the conductive particles for anisotropic conductive connection is 1% or more and 20% or less on the second connection layer side surface of the first connection layer. Are arranged in a single layer. For this reason, the conductive particles can be firmly fixed to the first connection layer, and the amount of resin in the first connection layer is not greatly reduced, so that tackiness and adhesive strength can be improved. Reflectively, the sticking property of the anisotropic conductive film is stably improved, and the productivity of anisotropic conductive connection is also improved. In addition, the photo-radically polymerizable resin layer below (back side) of the conductive particles in the first connection layer is not sufficiently irradiated with ultraviolet rays due to the presence of the conductive particles, so that the curing rate is relatively low and good indentation is achieved. As a result, good conduction reliability, insulation, and mounting conductive particle capture rate can be realized.

  In addition, when an anisotropic conductive connection utilizes heat, it becomes the method similar to the connection method of a normal anisotropic conductive film. In the case of using light, the connection tool may be pushed in until the reaction is completed. Even in this case, the connection tool or the like is often heated to promote resin flow and particle indentation. Moreover, what is necessary is just to carry out similarly to the above also when using heat and light together.

FIG. 1 is a cross-sectional view of the anisotropic conductive film of the present invention. Drawing 2 is an explanatory view of the manufacturing process (A) of the anisotropic conductive film of the present invention. FIG. 3A is an explanatory diagram of the production process (B) of the anisotropic conductive film of the present invention. FIG. 3B is an explanatory diagram of the production process (B) of the anisotropic conductive film of the present invention. FIG. 4A is an explanatory diagram of the production process (C) of the anisotropic conductive film of the present invention. FIG. 4B is an explanatory diagram of the production process (C) of the anisotropic conductive film of the present invention. FIG. 5 is a cross-sectional view of the anisotropic conductive film of the present invention. FIG. 6 is an explanatory view of the production process (AA) of the anisotropic conductive film of the present invention. FIG. 7A is an explanatory diagram of the production process (BB) of the anisotropic conductive film of the present invention. FIG. 7B is explanatory drawing of the manufacturing process (BB) of the anisotropic conductive film of this invention. FIG. 8A is explanatory drawing of the manufacturing process (CC) of the anisotropic conductive film of this invention. FIG. 8B is explanatory drawing of the manufacturing process (CC) of the anisotropic conductive film of this invention. FIG. 9A is explanatory drawing of the manufacturing process (DD) of the anisotropic conductive film of this invention. FIG. 9B is an explanatory diagram of the production process (DD) of the anisotropic conductive film of the present invention.

<< anisotropic conductive film >>
Hereinafter, a preferable example of the anisotropic conductive film of the present invention will be described in detail.

  As shown in FIG. 1, the anisotropic conductive film 1 of the present invention has heat or a photocation, an anion, or the like on one side of a first connection layer 2 composed of a photopolymerized resin layer obtained by photopolymerizing a photopolymerizable resin layer. It has a structure in which a second connection layer 3 made of a radical polymerizable resin layer is formed. On the surface 2a of the first connection layer 2 on the second connection layer 3 side, the conductive particles 4 are arranged in a single layer, preferably evenly arranged for anisotropic conductive connection. Here, “equal” means a state in which the conductive particles are arranged in the plane direction. This regularity may be provided at regular intervals.

<First connection layer 2>
Since the first connection layer 2 constituting the anisotropic conductive film 1 of the present invention is a photopolymerized resin layer obtained by photopolymerizing a photopolymerizable resin layer such as a photocation, anion or radical polymerizable resin layer, Particles can be immobilized. In addition, since it is polymerized, it becomes difficult for the resin to flow even when heated at the time of anisotropic conductive connection, so the occurrence of a short circuit can be greatly suppressed, thus improving the conduction reliability and insulation, and the mounting particle capture rate Can also be improved. The particularly preferable first connection layer 2 is a photo radical polymerization resin layer obtained by photo radical polymerization of a photo radical polymerizable resin layer containing an acrylate compound and a photo radical polymerization initiator. Hereinafter, the case where the 1st connection layer 2 is a radical photopolymerization resin layer is demonstrated.

(Acrylate compound)
As the acrylate compound serving as the acrylate unit, a conventionally known photoradical polymerizable acrylate can be used. For example, monofunctional (meth) acrylate (here, (meth) acrylate includes acrylate and methacrylate), and bifunctional or more polyfunctional (meth) acrylate can be used. In the present invention, it is preferable to use a polyfunctional (meth) acrylate for at least a part of the acrylic monomer in order to make the adhesive thermosetting.

  If the content of the acrylate compound in the first connection layer 2 is too small, the viscosity difference from the second connection layer 3 tends to be difficult, and if it is too large, the curing shrinkage tends to be large and workability tends to decrease. Preferably it is 2-70 mass%, More preferably, it is 10-50 mass%.

(Photo radical polymerization initiator)
As a radical photopolymerization initiator, it can be used by appropriately selecting from known radical photopolymerization initiators. Examples include acetophenone photopolymerization initiators, benzyl ketal photopolymerization initiators, and phosphorus photopolymerization initiators.

  If the amount of the radical photopolymerization initiator used is too small relative to 100 parts by mass of the acrylate compound, the radical photopolymerization will not proceed sufficiently, and if too large, it will cause a decrease in rigidity, so preferably 0.1 to 25 masses. Part, more preferably 0.5 to 15 parts by mass.

(Conductive particles)
The conductive particles can be appropriately selected from those used in conventionally known anisotropic conductive films. For example, metal particles such as nickel, cobalt, silver, copper, gold, and palladium, metal-coated resin particles, and the like can be given. Two or more kinds can be used in combination.

  The average particle size of the conductive particles is too small to absorb the variation in the height of the wiring and tends to increase the resistance, and if it is too large, it tends to cause a short circuit, preferably 1 to 10 μm, More preferably, it is 2-6 micrometers.

  If the amount of such conductive particles in the first connection layer 2 is too small, the number of trapped conductive particles is reduced and anisotropic conductive connection becomes difficult. The number is preferably 50 to 50000 per square mm, more preferably 200 to 30000.

  For the first connection layer 2, a film forming resin such as a phenoxy resin, an epoxy resin, an unsaturated polyester resin, a saturated polyester resin, a urethane resin, a butadiene resin, a polyimide resin, a polyamide resin, or a polyolefin resin is used in combination as necessary. be able to. Similarly, the second connection layer 3 and the third connection layer 5 may be used together.

  If the layer thickness of the first connection layer 2 is too thin, the mounting conductive particle trapping rate tends to decrease, and if it is too thick, the conduction resistance tends to increase, so that it is preferably 1.0 to 6.0 μm, more preferably. Is 2.0 to 5.0 μm.

  The first connection layer 2 may further contain an epoxy compound and a heat, photocation, or anionic polymerization initiator. In this case, as will be described later, the second connection layer 3 is also preferably a heat or photocation or anion polymerizable resin layer containing an epoxy compound and heat or a photocation or anion polymerization initiator. Thereby, delamination strength can be improved. The epoxy compound and the heat or photocation or anion polymerization initiator will be described in the second connection layer 3.

  In the first connection layer 2, the conductive particles 4 are embedded in the first connection layer 2 as shown in FIG. 1. When the degree of embedding is defined as the ratio (embedding rate) of the depth Lb embedded in the first connection layer of the conductive particles with respect to the particle diameter La of the conductive particles, the embedding rate is expressed as “embedding rate”. (%) = (Lb / La) × 100 ”. In the present invention, the problem that “the conductive particles can be fixed at an intended position in order to realize good mounting conductive particle capturing property” and “the adhesive strength between the first connection layer 2 and the adherend are to be achieved. In order to solve the problem of ensuring good tackiness by securing the amount of resin present below the conductive particles in order to improve the conductivity, the embedding rate of the conductive particles in the first connection layer 2 is The lower limit is adjusted to 1% or more, preferably greater than 1%, and the upper limit is adjusted to 20% or less, preferably less than 20%.

  In addition, adjustment of the embedding rate of the conductive particles 4 in the first connection layer 2 can be performed, for example, by repeatedly pressing with a rubber roll provided with a release material on the surface. Specifically, when the embedding rate is reduced, the number of repetitions may be reduced, and when it is increased, the number of repetitions may be increased.

  In addition, when the first connection layer 2 is formed by irradiating the photopolymerizable resin layer with ultraviolet rays, the first polymerizable layer 2 is irradiated from either the surface where the conductive particles are not disposed or the surface where the conductive particles are disposed. However, when irradiated from the side on which the conductive particles are disposed, the first connection layer 2 has a first region located between the conductive particles 4 and the outermost surface 2b of the first connection layer 2. The curing rate of the connection layer portion 2X can be made lower than the curing rate of the first connection layer portion 2Y in the region located between the conductive particles 4 adjacent to each other. As a result, the first connection layer portion 2X is easily removed during the thermocompression bonding of the anisotropic conductive connection, and the conduction reliability is improved. Here, the curing rate is a numerical value defined as a vinyl group reduction ratio, the curing rate of the first connection layer portion 2X is preferably 40 to 80%, and the curing rate of the first connection layer portion 2Y is preferably 70 to 100%.

  Here, when irradiating from the surface where the conductive particles are not disposed, the difference in the curing rate between the first connection layer portions 2X and 2Y is substantially eliminated. This is preferable in terms of ACF product quality. This is because in the ACF manufacturing process, the fixing of the conductive particles is promoted, and stable quality can be ensured. This is because, when the length is increased as a general product, the pressure applied to the arranged conductive particles can be made substantially the same at the start and end of winding, and the disorder of the arrangement can be prevented.

  The radical photopolymerization at the time of forming the first connection layer 2 may be performed in one step (that is, one time of light irradiation), but may be performed in two steps (that is, two times of light irradiation). Good. In this case, the second-stage light irradiation is performed from the other surface side of the first connection layer 2 in an oxygen-containing atmosphere (in the atmosphere) after the second connection layer 3 is formed on one surface of the first connection layer 2. It is preferable. Thereby, it can be expected that the radical polymerization reaction is oxygen-inhibited, the surface concentration of the uncured component is increased, and tackiness can be improved. In addition, since the polymerization reaction is complicated by performing the curing in two stages, it can be expected that the fluidity of the resin and particles can be precisely controlled.

  The curing rate in the first stage of the first connection layer portion 2X in the two-stage photoradical polymerization is preferably 10 to 50%, and the curing ratio in the second stage is preferably 40 to 80%. The curing rate in the first stage of the one connection layer 2Y is preferably 30 to 90%, and the curing rate in the second stage is preferably 70 to 100%.

  Further, when the photoradical polymerization reaction at the time of forming the first connection layer 2 is performed in two stages, only one type can be used as the radical polymerization initiator, but two types with different wavelength bands for starting the radical reaction can be used. The radical photopolymerization initiator is preferably used for improving tackiness. For example, IRGACURE 369 (BASF Japan Co., Ltd.) that initiates a radical reaction with light having a wavelength of 365 nm from an LED light source, and IRGACURE 2959 (BASF) that initiates a radical reaction with light from a high-pressure mercury lamp light source. Japan) is preferably used in combination. As described above, since the bonding of the resin is complicated by using two different curing agents, it becomes possible to more precisely control the behavior of the thermal flow of the resin at the time of connection. This is because, when the anisotropic conductive connection is pushed in, the particles are easily subjected to a force in the thickness direction, but the flow in the surface direction is suppressed, so that the effect of the present invention is more easily manifested.

  Further, the minimum melt viscosity when measured with the rheometer of the first connection layer 2 is higher than the minimum melt viscosity of the second connection layer 3, specifically, [the minimum melt viscosity of the first connection layer 2 (mPa The numerical value of s)] / [minimum melt viscosity (mPa · s) of the second connection layer 3] is preferably 1 to 1000, more preferably 4 to 400. In addition, each preferable minimum melt viscosity is 100-100000 mPa * s about the former, More preferably, it is 500-50000 mPa * s. About the latter, Preferably it is 0.1-10000 mPa * s, More preferably, it is 0.5-1000 mPa * s.

  The first connection layer 2 is formed on a photo radical polymerizable resin layer containing a photo radical polymerizable acrylate and a photo radical polymerization initiator by a film transfer method, a mold transfer method, an ink jet method, an electrostatic adhesion method, or the like. Conductive particles can be attached by a technique, and ultraviolet rays can be irradiated from the conductive particle side, the opposite side, or both sides. In particular, it is preferable to irradiate ultraviolet rays only from the conductive particle side from the viewpoint that the curing rate of the first connection layer portion 2X can be suppressed relatively low.

<Second connection layer 3>
The second connection layer 3 is a heat or photocation, anion or radical polymerizable resin layer, preferably a heat or photocation or anion polymerizable resin layer containing an epoxy compound and a heat or photocation or anion polymerization initiator, or It consists of a heat or photo radical polymerizable resin layer containing an acrylate compound and a heat or photo radical polymerization initiator. Here, forming the second connection layer 3 from the thermopolymerizable resin layer does not cause a double polymerization reaction of the second connection layer 3 due to ultraviolet irradiation when the first connection layer 2 is formed. In terms of stability and quality stability.

  When the second connection layer 3 is a heat, photocation or anion polymerizable resin layer, it can further contain an acrylate compound and a heat or photo radical polymerization initiator. Thereby, the 1st connection layer 2 and delamination strength can be improved.

(Epoxy compound)
When the second connection layer 3 is a heat or photocation or anion polymerizable resin layer containing an epoxy compound and a heat or photocation or anion polymerization initiator, the epoxy compound has two or more epoxy groups in the molecule. Preferred are compounds or resins having These may be liquid or solid.

(Thermal cationic polymerization initiator)
As the thermal cationic polymerization initiator, those known as the thermal cationic polymerization initiator of the epoxy compound can be adopted, for example, those which generate an acid capable of cationically polymerizing the cationic polymerizable compound by heat. Iodonium salts, sulfonium salts, phosphonium salts, ferrocenes, and the like can be used, and aromatic sulfonium salts exhibiting good potential with respect to temperature can be preferably used.

  If the amount of the thermal cationic polymerization initiator is too small, curing tends to be poor, and if it is too much, product life tends to decrease. Therefore, it is preferably 2 to 60 masses per 100 mass parts of the epoxy compound. Part, more preferably 5 to 40 parts by weight.

(Thermal anionic polymerization initiator)
As the thermal anionic polymerization initiator, those known as the thermal anionic polymerization initiator of the epoxy compound can be employed. For example, a base capable of anionic polymerization of the anionic polymerizable compound is generated by heat, and is publicly known. Aliphatic amine compounds, aromatic amine compounds, secondary or tertiary amine compounds, imidazole compounds, polymercaptan compounds, boron trifluoride-amine complexes, dicyandiamide, organic acid hydrazides, etc. can be used. An encapsulated imidazole compound showing good potential with respect to temperature can be preferably used.

  If the amount of the thermal anionic polymerization initiator is too small, it tends to be poorly cured, and if it is too much, the product life tends to decrease. Therefore, it is preferably 2 to 60 masses per 100 mass parts of the epoxy compound. Part, more preferably 5 to 40 parts by weight.

(Photocationic polymerization initiator and photoanionic polymerization initiator)
A well-known thing can be used suitably as a photocationic polymerization initiator or photoanion polymerization initiator for epoxy compounds.

(Acrylate compound)
When the second connection layer 3 is a heat or photo radical polymerizable resin layer containing an acrylate compound and a heat or photo radical polymerization initiator, the acrylate compound is appropriately selected from those described for the first connection layer 2 Can be used.

(Thermal radical polymerization initiator)
Further, examples of the thermal radical polymerization initiator include organic peroxides and azo compounds, but organic peroxides that do not generate nitrogen that causes bubbles can be preferably used.

  If the amount of the thermal radical polymerization initiator used is too small, curing will be poor, and if it is too large, the product life will be reduced. Therefore, the amount is preferably 2 to 60 parts by weight, more preferably 5 to 40 parts per 100 parts by weight of the acrylate compound. Part by mass.

(Photo radical polymerization initiator)
As a radical photopolymerization initiator for the acrylate compound, a known radical photopolymerization initiator can be used.

  If the amount of the radical photopolymerization initiator used is too small, curing will be poor, and if it is too large, the product life will be reduced. Part by mass.

(Third connection layer 5)
The anisotropic conductive film having the two-layer structure in FIG. 1 has been described above, but the third connection layer 5 may be formed on the other surface of the first connection layer 2 as shown in FIG. Thereby, the effect that it becomes possible to control the fluidity | liquidity of the whole layer more precisely is acquired. Here, the third connection layer 5 may have the same configuration as the second connection layer 3 described above. That is, the third connection layer 5 is made of a heat or photocation, anion, or radical polymerizable resin layer, like the second connection layer 3. The third connection layer 5 may be formed on the other surface of the first connection layer after the second connection layer is formed on one surface of the first connection layer. Before the second connection layer is formed, the third connection layer 5 may be formed. The third connection layer may be formed in advance on the other surface (the surface on which the second connection layer is not formed) of one connection layer or a photopolymerizable resin layer that is a precursor thereof.

<< Method for Manufacturing Anisotropic Conductive Film >>
Examples of the method for producing an anisotropic conductive film of the present invention include a production method for carrying out a one-stage photopolymerization reaction and a production method for carrying out a two-stage photopolymerization reaction.

<Production method for carrying out one-step photopolymerization reaction>
An example in which the anisotropic conductive film of FIG. 1 (FIG. 4B) is produced by photopolymerization in one step will be described. This production example has the following steps (A) to (C).

(Process (A))
As shown in FIG. 2, the conductive particles 4 are arranged in a single layer so that the embedding rate is 1% or more and 20% or less in the photopolymerizable resin layer 31 formed on the release film 30 as necessary. Let The method for arranging the conductive particles 4 is not particularly limited, and a method using a biaxial stretching operation for the unstretched polypropylene film of Example 1 of Japanese Patent No. 4778938, or a mold disclosed in JP 2010-33793 A is used. The method used can be adopted. The degree of arrangement is preferably two-dimensionally separated from each other by about 1 to 100 μm in consideration of the size of the connection target, conduction reliability, insulation, mounting conductive particle capture rate, and the like.

  The embedding rate can be adjusted by repeatedly pressing an elastic body such as a rubber roll.

(Process (B))
Next, as shown in FIG. 3A, the photopolymerizable resin layer 31 in which the conductive particles 4 are arranged is subjected to a photopolymerization reaction by irradiating ultraviolet rays (UV), and the conductive particles 4 are fixed on the surface. The first connection layer 2 is formed. In this case, ultraviolet rays (UV) may be irradiated from the conductive particle side or from the opposite side, but when ultraviolet rays (UV) are irradiated from the conductive particle side, as shown in FIG. The curing rate of the first connection layer portion 2X in the region located between the conductive particles 4 and the outermost surface of the first connection layer 2 is set to the first connection layer portion 2Y in the region located between the adjacent conductive particles 4. It can be made lower than the curing rate. By doing so, the curability of the back side of the particles is surely lowered, the pushing at the time of joining is facilitated, and the effect of preventing the flow of the particles can be provided at the same time.

(Process (C))
Next, as shown in FIG. 4A, the second connection layer 3 made of heat, photocation, anion, or radical polymerizable resin layer is formed on the surface of the first connection layer 2 on the conductive particle 4 side. As a specific example, the second connection layer 3 formed on the release film 40 by a conventional method is placed on the surface of the first connection layer 2 on the conductive particle 4 side, and thermocompression-bonded to such an extent that excessive thermal polymerization does not occur. Then, by removing the release films 30 and 40, the anisotropic conductive film of FIG. 4B can be obtained.

In addition, the anisotropic conductive film 100 of FIG. 5 can be obtained by implementing the following processes (Z) after a process (C).
(Process (Z))
A third connection layer made of a heat, photocation, anion, or radical polymerizable resin layer is formed on the opposite surface of the first connection layer on the conductive particle side, preferably in the same manner as the second connection layer. Thereby, the anisotropic conductive film of FIG. 5 can be obtained.

  Moreover, the anisotropic conductive film 100 of FIG. 5 can also be obtained by performing the following process (a) prior to the process (A) without performing the process (Z).

(Process (a))
A step of forming a third connection layer comprising a heat or photocation, anion or radical polymerizable resin layer on one surface of the photopolymerizable resin layer. Subsequent to the step (a), the anisotropic conductive film 100 of FIG. 5 can be obtained by carrying out the steps (A), (B) and (C). However, in the step (A), conductive particles are arranged in a single layer on the other surface of the photopolymerizable resin layer so that the embedding rate is 1% or more and 20% or less.

(Manufacturing method that performs a two-stage photopolymerization reaction)
Next, an example of producing the anisotropic conductive film of FIG. 1 (FIG. 4B) by photopolymerization in two steps will be described. This production example includes the following steps (AA) to (DD).

(Process (AA))
As shown in FIG. 6, the conductive particles 4 are arranged in a single layer so that the embedding rate is 1% or more and 20% or less in the photopolymerizable resin layer 31 formed on the release film 30 as necessary. . The method for arranging the conductive particles 4 is not particularly limited, and a method using a biaxial stretching operation for the unstretched polypropylene film of Example 1 of Japanese Patent No. 4778938, or a mold disclosed in JP 2010-33793 A is used. The method used can be adopted. The degree of arrangement is preferably two-dimensionally separated from each other by about 1 to 100 μm in consideration of the size of the connection target, conduction reliability, insulation, mounting conductive particle capture rate, and the like.

(Process (BB))
Next, as shown in FIG. 7A, the photopolymerizable resin layer 31 in which the conductive particles 4 are arranged is subjected to a photopolymerization reaction by irradiating ultraviolet rays (UV), and the conductive particles 4 are temporarily fixed on the surface. The temporary first connection layer 20 is formed. In this case, ultraviolet rays (UV) may be irradiated from the conductive particle side or from the opposite side, but when ultraviolet rays (UV) are irradiated from the conductive particle side, as shown in FIG. The hardening rate of the temporary first connection layer portion 2X in the region located between the conductive particles 4 and the outermost surface of the temporary first connection layer 20 is set to the temporary first connection in the region located between the adjacent conductive particles 4. It can be made lower than the curing rate of the layer portion 2Y.

(Process (CC))
Next, as shown in FIG. 8A, the second connection layer 3 made of a thermal cation, anion, or radical polymerizable resin layer is formed on the surface of the temporary first connection layer 20 on the conductive particle 4 side. As a specific example, the second connection layer 3 formed on the release film 40 by a conventional method is placed on the surface of the first connection layer 2 on the conductive particle 4 side, and thermocompression-bonded to such an extent that excessive thermal polymerization does not occur. Then, the temporary anisotropic conductive film 50 of FIG. 8B can be obtained by removing the release films 30 and 40.

(Process (DD))
Next, as shown in FIG. 9A, the temporary first connection layer 20 is irradiated with ultraviolet rays from the side opposite to the second connection layer 3 to undergo a photopolymerization reaction, and the temporary first connection layer 20 is fully cured to be first. The connection layer 2 is formed. Thereby, the anisotropic conductive film 1 of FIG. 9B can be obtained. The ultraviolet irradiation in this step is preferably performed from a direction perpendicular to the temporary first connection layer. Moreover, in order not to lose | disappear the hardening rate difference of 1st connection layer part 2X and 2Y, it is preferable to irradiate through a mask or to provide a difference in irradiation light quantity by an irradiation site | part.

When photopolymerization is performed in two stages, the anisotropic conductive film 100 in FIG. 5 can be obtained by performing the following step (Z) after the step (DD).
(Process (Z))
A third connection layer made of a heat, photocation, anion, or radical polymerizable resin layer is formed on the opposite surface of the first connection layer on the conductive particle side, preferably in the same manner as the second connection layer. Thereby, the anisotropic conductive film of FIG. 5 can be obtained.

  Moreover, the anisotropic conductive film 100 of FIG. 5 can also be obtained by performing the following process (a) prior to the process (AA) without performing the process (Z).

(Process (a))
This step is a step of forming a third connection layer made of heat, photocation, anion, or radical polymerizable resin layer on one surface of the photo radical polymerizable resin layer. Subsequent to the step (a), the anisotropic conductive film 100 of FIG. 5 can be obtained by performing the steps (AA) to (DD). However, in the step (AA), conductive particles are arranged in a single layer so that the embedding rate is 1% or more and 20% or less on the other surface of the photopolymerizable resin layer. In this case, it is preferable to apply a thermal polymerization initiator as a polymerization initiator used in forming the second connection layer. In the case of a photopolymerization initiator, there is a concern that the product life as an anisotropic conductive film, connection, and stability of the connection structure may be adversely affected in the process.

<< Connection structure >>
The anisotropic conductive film thus obtained is preferably applied when anisotropically conductively connecting a first electronic component such as an IC chip or IC module and a second electronic component such as a flexible substrate or a glass substrate. can do. The connection structure thus obtained is also part of the present invention. Note that the first connection layer side of the anisotropic conductive film is disposed on the second electronic component side such as a flexible substrate, and the second connection layer side is disposed on the first electronic component side such as an IC chip. It is preferable from the point of improving the property.

  Hereinafter, the present invention will be specifically described by way of examples.

Examples 1-5, Comparative Examples 1-2
The conductive particles are arranged in accordance with the operation of Example 1 of Japanese Patent No. 4778938, and the difference in the two-layer structure in which the first connection layer and the second connection layer are laminated according to the formulation (parts by mass) shown in Table 1. An anisotropic conductive film was prepared.

(First connection layer)
Specifically, first, a mixed solution of an acrylate compound, a radical photopolymerization initiator, and the like was prepared using ethyl acetate or toluene so that the solid content was 50% by mass. This mixed solution is applied to a polyethylene terephthalate film having a thickness of 50 μm so as to have a dry thickness of 5 μm, and dried in an oven at 80 ° C. for 5 minutes, whereby radical photopolymerization that is a precursor layer of the first connection layer is performed. A functional resin layer was formed.

Next, conductive particles (Ni / Au plating resin particles, AUL 704, Sekisui Chemical Co., Ltd.) having an average particle diameter of 4 μm are separated from each other by 4 μm from the obtained radical photopolymerizable resin layer, and repeated by a rubber roll. By adjusting the number of times of pressing, the conductive particles were arranged in a single layer so that the embedding rate of the conductive particles in the first connection layer was the percentage shown in Table 1. Furthermore, the first connection layer having conductive particles fixed on the surface was formed by irradiating the radical photopolymerizable resin layer with ultraviolet rays having a wavelength of 365 nm and an integrated light amount of 4000 mJ / cm ² from the conductive particle side.

(Second connection layer)
A liquid mixture of a thermosetting resin and a latent curing agent was prepared with ethyl acetate or toluene so that the solid content was 50% by mass. This mixed solution was applied to a polyethylene terephthalate film having a thickness of 50 μm so as to have a dry thickness of 12 μm, and dried in an oven at 80 ° C. for 5 minutes to form a second connection layer.

(Anisotropic conductive film)
An anisotropic conductive film was obtained by laminating the first connection layer and the second connection layer thus obtained so that the conductive particles were inside.

(Connection structure sample)
Using the obtained anisotropic conductive film, an IC chip (bump size 30 × 85 μm: bump height 15 μm, bump pitch 50 μm) of 0.5 × 1.8 × 20.0 mm is 0.5 The sample was mounted on a glass wiring board (1737F) manufactured by Corning having a size of × 50 × 30 mm under the conditions of 180 ° C., 80 MPa, and 5 seconds to obtain a connection structure sample body.

(Test evaluation)
About the obtained connection structure sample body, as described below, “tack force”, “adhesion strength (die shear)”, “mounting conductive particle capture rate”, Test and evaluation of “conduction reliability” and “insulation” were conducted. The obtained results are shown in Table 1.

  In the case of evaluation of “insulating”, an IC chip having a size of 0.5 × 1.5 × 13 mm (gold-plated bump size 25 × 140 μm: bump height 15 μm, space between bumps 7.5 μm) A connection structure sample body obtained by mounting on a glass wiring board (1737F) manufactured by Corning Inc. having a size of 0.5 × 50 × 30 mm under the conditions of 180 ° C., 80 MPa, and 5 seconds was used.

"Tack power"
The tack force of the first connection layer of the anisotropic conductive film was measured using a tack tester (TACII, Resca Co., Ltd.) in accordance with JIS Z0237 “Adhesive tape / adhesive sheet test method” under an atmosphere of 22 ° C. Measurement was performed by pressing the probe against the first connection layer side of the anisotropic conductive film under the measurement conditions of a probe diameter of 5 mm (stainless steel mirror surface, cylindrical shape), a pressing load of 196 kgf, a pressing speed of 30 mm / min, and a peeling speed of 5 mm / min. . The peak intensity of the measurement chart was taken as tack force (kPa).

"Adhesive strength (die share)"
About each produced connection structure sample body, the die shear intensity | strength was measured using the die shear measuring machine (Product name: Dage2400, the Daigi company make). Practically 600N or more is preferable.

"Mounting conductive particle capture rate"
Particles that are actually trapped on the bumps of the connection structure sample body after heating / pressurization (after actual mounting) against the “theoretical particle amount existing on the bumps of the connection structure sample body before heating / pressurization” The ratio of “amount” was determined according to the following formula.

"Conduction reliability"
The conduction resistance after the connection structure sample was left in a high-temperature and high-humidity environment of 85 ° C. and 85% RH for 500 hours was measured using a digital multimeter (Agilent Technology Co., Ltd.). Practically, it is desirable that it is 4Ω or less.

“Insulation (occurrence of short circuit)”
The short-circuit occurrence rate of the comb tooth TEG pattern in the 7.5 μm space was determined. Practically, it is desirably 100 ppm or less.

  As can be seen from Table 1, the anisotropic conductive films of Examples 1 to 5 are practically preferable for the evaluation items of tack force, connection strength, mounting conductive particle capture rate, conduction reliability, and insulation. Results are shown.

  On the other hand, with respect to the anisotropic conductive film of Comparative Example 1, the embedding rate of the conductive particles with respect to the first connection layer exceeded 20%. The strength was inferior. Further, the occurrence rate of short circuit has increased by about 2.5 times. About the anisotropic conductive film of the comparative example 2, since the embedding rate of the conductive particle with respect to the 1st connection layer was less than 1%, compared with the anisotropic conductive film of an Example, a mounting conductive particle capture rate falls. In addition, the short-circuit occurrence rate, which is an evaluation index for insulation, has increased by about 7.5 times.

Example 6
An anisotropic conductive film was produced in the same manner as in Example 1 except that ultraviolet rays were irradiated with an integrated light amount of 2000 mJ / cm ² when forming the first connection layer. Anisotropy of Example 6 in which ultraviolet rays were irradiated from both sides of the first connection layer by further irradiating ultraviolet rays having a wavelength of 365 nm with an integrated light quantity of 2000 mJ / cm ² from the first connection layer side of the anisotropic conductive film. Conductive film was obtained. Using this anisotropic conductive film, a connection structure sample was prepared and evaluated in the same manner as the anisotropic conductive film of Example 1, and almost the same practically no problem was obtained. The particle capture rate tended to be further improved.

  The anisotropic conductive film of the present invention has a two-layer structure in which a first connection layer made of a photopolymerizable resin layer and a second connection layer made of a heat or photocation, anion or radical polymerizable resin layer are laminated. Furthermore, the conductive particles for anisotropic conductive connection on the surface of the first connection layer on the second connection layer side have an embedding rate of 1% or more and 20% or less in the first connection layer. Are arranged in a single layer. For this reason, a 1st connection layer shows favorable tack property and connection intensity | strength, and shows favorable conduction | electrical_connection reliability, insulation, and a mounting conductive particle capture rate. Therefore, it is useful for anisotropic conductive connection of an electronic component such as an IC chip to a wiring board. The wiring of such electronic parts is being narrowed, and the present invention particularly exhibits its effect when it contributes to such technical progress.

DESCRIPTION OF SYMBOLS 1,100 Anisotropic conductive film 2, 1st connection layer 2X, 2Y 1st connection layer part 3 2nd connection layer 4 Conductive particle 5 3rd connection layer 30, 40 Release film 20 Temporary 1st connection layer 31 Photopolymerizable Resin layer 50 Temporary anisotropic conductive film La Particle diameter Lb of conductive particles Depth embedded in first connection layer of conductive particles

Claims (16)

An anisotropic conductive film having a first connection layer and a second connection layer formed on one side thereof,
The first connection layer is a photopolymerization resin layer;
The second connection layer is a heat or photocation, anion or radical polymerizable resin layer;
Conductive particles for anisotropic conductive connection are arranged in a single layer on the second connection layer side surface of the first connection layer, and the embedding rate of the conductive particles in the first connection layer is 1% or more and 20% or less. An anisotropic conductive film, wherein   The anisotropic conductive film according to claim 1, wherein the first connection layer is a photo radical polymerization resin layer obtained by photo radical polymerization of a photo radical polymerizable resin layer containing an acrylate compound and a photo radical polymerization initiator.   The anisotropic conductive film according to claim 2, wherein the first connection layer further contains an epoxy compound and a heat, photocation, or anionic polymerization initiator.   The second connection layer is a heat containing an epoxy compound and heat or a photocation or anion polymerization initiator, or a heat or photocation or anion polymerizable resin layer, or a heat containing an acrylate compound and a heat or radical polymerization initiator, or The anisotropic conductive film according to claim 1, which is a radical photopolymerizable resin layer.   The second connection layer is a heat or photocation or anion polymerizable resin layer containing an epoxy compound and heat or a photocation or anion polymerization initiator, and further contains an acrylate compound and a heat or photoradical polymerization initiator. The anisotropic conductive film according to claim 4.   In the first connection layer, the curing rate of the first connection layer in the region located between the conductive particles and the outermost surface of the first connection layer is such that the curing rate of the first connection layer in the region located between the adjacent conductive particles. The anisotropic conductive film in any one of Claims 1-5 lower than a cure rate.   The anisotropic conductive film in any one of Claims 1-6 whose minimum melt viscosity of a 1st connection layer is higher than the minimum melt viscosity of a 2nd connection layer. It is a manufacturing method of the anisotropic conductive film of Claim 1, Comprising: The following processes (A)-(C):
Process (A)
Arranging the conductive particles in the photopolymerizable resin layer in a single layer so that the embedding rate of the conductive particles in the first connection layer is 1% or more and 20% or less;
Process (B)
A step of forming a first connection layer in which conductive particles are fixed on the surface by irradiating the photopolymerizable resin layer in which the conductive particles are arranged by irradiating with ultraviolet rays; and step (C)
The manufacturing method which has the process of forming the 2nd connection layer which consists of a heat | fever or a photocation, an anion, or a radically polymerizable resin layer in the electrically conductive particle side surface of a 1st connection layer.   The production method according to claim 8, wherein the ultraviolet irradiation in the step (B) is performed from the side where the conductive particles of the photopolymerizable resin layer are arranged. It is a manufacturing method of the anisotropic conductive film of Claim 1, Comprising: The following processes (AA)-(DD):
Process (AA)
Arranging the conductive particles in the photopolymerizable resin layer in a single layer so that the embedding rate of the conductive particles in the first connection layer is 1% or more and 20% or less;
Process (BB)
A step of forming a temporary first connection layer in which the conductive particles are temporarily fixed on the surface by irradiating the photopolymerizable resin layer in which the conductive particles are arranged with an ultraviolet ray to cause a photopolymerization reaction;
Process (CC)
Forming a second connection layer comprising a thermal cation, anion, or radical polymerizable resin layer on the surface of the temporary first connection layer on the conductive particle side; and step (DD)
The manufacturing method which has a process which carries out photopolymerization reaction by irradiating a temporary 1st connection layer by irradiating an ultraviolet-ray from the opposite side to a 2nd connection layer, and main-hardens a temporary 1st connection layer, and forms a 1st connection layer.   The manufacturing method of Claim 10 which performs the ultraviolet irradiation of a process (BB) from the side in which the electrically conductive particle of the photopolymerizable resin layer arranged. The manufacturing method according to claim 8, wherein after the step (C), the following step (Z):
Step (Z)
The manufacturing method which has the process of forming the 3rd connection layer which consists of a heat | fever or a photocation, an anion, or a radically polymerizable resin layer in the surface opposite to the electroconductive particle side of a 1st connection layer. 9. The manufacturing method according to claim 8, wherein prior to step (A), the following step (a):
Step (a)
A step of forming a third connection layer comprising a heat or photocationic, anionic or radically polymerizable resin layer on one side of the photopolymerizable resin layer; in step (A), on the other side of the photopolymerizable resin layer; A production method in which conductive particles are arranged in a single layer at an embedding rate of 1% or more and 20% or less. The manufacturing method according to claim 10, wherein after the step (DD), the following step (Z):
Step (Z)
The manufacturing method which has the process of forming the 3rd connection layer which consists of a heat | fever or a photocation, an anion, or a radically polymerizable resin layer in the surface opposite to the electroconductive particle side of a 1st connection layer. The manufacturing method according to claim 10, wherein, prior to step (AA), the following step (a):
Step (a)
A step of forming a third connection layer made of heat, photocation, anion, or radical polymerizable resin layer on one side of the photopolymerizable resin layer; and in step (AA), A production method in which conductive particles are arranged in a single layer at an embedding rate of 1% or more and 20% or less.   The connection structure which anisotropically connected the 1st electronic component to the 2nd electronic component with the anisotropic conductive film in any one of Claims 1-7.

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