JP2015147823A - Anisotropic conductive film and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve good connection reliability, good insulation properties and good particle capture efficiency in an anisotropic conductive film which has a multilayer structure having conductive particles arranged in a single layer.SOLUTION: There is provided an anisotropic conductive film 1 obtained by laminating a first insulating resin layer 2, an intermediate insulating resin layer 4 and a second insulating resin layer 3 in order. The first insulating resin layer 2 is formed of a photopolymerizable resin, the intermediate insulating resin layer 4 is formed of a resin containing no polymerization initiator, the second insulating resin layer 3 is formed of a heat-cationic or heat-anionic polymerizable resin, a photo cationic or photo anionic polymerizable resin, a heat-radical polymerizable resin or a photo-radical polymerizable resin. Conductive particles 10 for anisotropic conductive connection are arranged in a single layer on the side surface of the second insulating resin layer 3 of the first insulating resin layer 2 and are in contact with the intermediate insulating resin layer 4.

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, and in recent years, from the viewpoint of application to high mounting density, improved connection reliability and insulation, improved conductive particle capture rate, For the purpose of reducing manufacturing costs, an anisotropic conductive film formed of conductive particles for anisotropic conductive connection arranged in a single layer and an insulating resin layer having a two-layer structure has been proposed (Patent Document). 1).

  In this anisotropic conductive film, conductive particles are arranged in a single layer and densely in an adhesive layer, and the adhesive layer is biaxially stretched to form a sheet in which conductive particles are arranged. Another insulating resin layer that contains a thermosetting resin but does not contain a latent curing agent on the conductive particles transferred to the insulating resin layer containing the thermosetting resin and the latent curing agent. (Patent Document 1).

Japanese Patent No. 4778938

  However, since the anisotropic conductive film of Patent Document 1 uses an insulating resin layer that does not contain a latent curing agent, it contains a latent curing agent by heating during anisotropic conductive connection. Since a relatively large resin flow easily occurs in the insulating resin layer that is not formed, and the conductive particles easily flow along the flow, the conductive particles are arranged at equal intervals in a single layer by biaxial stretching. However, problems such as a decrease in the capture rate of conductive particles and occurrence of short circuits (decrease in insulation) occur.

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

  The present inventor arranges conductive particles as a single layer on one side of the photopolymerizable resin layer, immobilizes the conductive particles on the photopolymerization resin by irradiating ultraviolet rays, and further encloses the conductive particles around the immobilized conductive particles. The above-mentioned object of the present invention can be achieved by an anisotropic conductive film in which an intermediate insulating resin layer is provided as a stress relaxation layer and a polymerizable resin layer that is polymerized by heat or light is laminated thereon. As a result, the present invention has been completed.

That is, the present invention is an anisotropic conductive film in which a first insulating resin layer, an intermediate insulating resin layer, and a second insulating resin layer are sequentially laminated,
The first insulating resin layer is formed of a photopolymerization resin;
The second insulating resin layer is formed of a thermal cation or thermal anion polymerizable resin, a photo cation or photo anion polymerizable resin, a thermal radical polymerizable resin, or a photo radical polymerizable resin,
The intermediate insulating resin layer is formed of a resin not containing a polymerization initiator,
Conductive particles for anisotropic conductive connection are arranged as a single layer on the second insulating resin layer side surface of the first insulating resin layer, and the conductive particles are in contact with the intermediate insulating resin layer. Provide film.

  The second insulating resin layer is preferably a thermopolymerizable resin layer using a thermal polymerization initiator that initiates a polymerization reaction by heating, but a photopolymerization initiator that initiates a polymerization reaction by light is used. It may be a photopolymerizable resin layer. A thermal / photopolymerizable resin layer in which a thermal polymerization initiator and a photopolymerization initiator are used in combination may be used.

Moreover, this invention is a manufacturing method of the above-mentioned anisotropic conductive film, Comprising: The following processes (A)-(D):
Process (A)
Arranging the conductive particles in a single layer on the photopolymerizable resin layer;
Process (B)
A step of causing a photopolymerization reaction by irradiating the photopolymerizable resin layer in which the conductive particles are arranged with ultraviolet rays to form a first insulating resin layer having the conductive particles fixed on the surface;
Process (C)
Forming a second insulating resin layer formed of a thermal cation or thermal anion polymerizable resin, a photo cation or photo anion polymerizable resin, a thermal radical polymerizable resin, or a photo radical polymerizable resin;
Process (D)
Forming an intermediate insulating resin layer formed of a resin not containing a polymerization initiator on the conductive particle side surface of the first insulating resin layer;
Have
(i) An intermediate insulating resin layer is formed on the conductive particle side surface of the first insulating resin layer by performing the step (D) after the step (B), and then the intermediate insulating resin layer and the step (C) Or laminating the second insulating resin layer formed in
(ii) On the second insulating resin layer formed in step (C), an intermediate insulating resin layer formed of a resin not containing a polymerization initiator is formed, and then the intermediate insulating resin layer is formed in the step ( The manufacturing method of laminating | stacking on the electrically-conductive particle side surface of the 1st insulating resin layer formed in B) is provided.

  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 includes a first insulating resin layer obtained by photopolymerization of a photopolymerizable resin layer, an intermediate insulating resin layer formed of a resin not containing a polymerization initiator, and polymerized by heat or light. The second insulating resin layers are sequentially laminated, and further, conductive particles for anisotropic conductive connection are arranged in a single layer on the surface of the first insulating resin layer on the second insulating resin layer side. Has been. Therefore, the conductive particles can be firmly fixed by the photopolymerized first insulating resin layer. Moreover, an intermediate insulating resin layer is provided around the conductive particles, and this intermediate insulating resin layer is used when the anisotropic conductive film is wound, unwound, transported, and anisotropic conductive connection step. The stress applied to the conductive particles is eased when the film is pulled out. Therefore, the anisotropic conductive film of the present invention can achieve a good conductive particle capture rate, conduction reliability, and a low short-circuit occurrence rate.

  In particular, when forming the first insulating resin layer, if the photopolymerizable resin is irradiated with ultraviolet rays from the conductive particle side, the photopolymerizable resin below the conductive particles (back side) becomes a shadow of the conductive particles, and thus the ultraviolet rays are exposed. Will not be sufficiently irradiated. Therefore, the photopolymerization resin shaded by the conductive particles has a lower curing rate than the photopolymerization resin not shaded, and the conductive particles are pushed better during anisotropic conductive connection. Good conduction reliability and insulation can be realized.

  On the other hand, in forming the first insulating resin layer, when the photopolymerizable resin is irradiated with ultraviolet rays from the opposite side or both sides of the conductive particles, the fixing of the conductive particles is promoted, and in the production line of the anisotropic conductive film, Stable quality can be ensured. In addition, even if an anisotropic conductive film is subjected to unnecessary external stress during winding of the anisotropic conductive film onto a reel or drawing the film from the reel during anisotropic conductive connection, The influence of external stress is less likely to affect the arrangement of the conductive particles before the conductive connection.

In the anisotropic conductive film of the present invention, when the second insulating resin layer is formed of a polymerizable resin that reacts with heat, the anisotropic conductive connection of an electronic component using the second insulating resin layer is different from a normal one. It can carry out similarly to the connection method using an anisotropic conductive film.
On the other hand, in the anisotropic conductive film of the present invention, when the second insulating resin layer is formed of a polymerizable resin that reacts with light, the anisotropy of the first electronic component and the second electronic component using the same is used. The conductive connection may be pushed by the connection tool until the photoreaction is finished. In this case as well, the connection tool or the like may be heated to promote resin flow or particle pushing. In addition, in the second insulating resin layer, when a polymerizable resin that reacts with heat and a polymerizable resin that reacts with light are used in combination, the connection tool is pushed in until the photoreaction is completed as described above. And heating may be performed.

  In addition, when the first electronic component and the second electronic component are anisotropically conductively connected using a photoreaction, light irradiation may be performed from the electronic component side having translucency.

FIG. 1A is a cross-sectional view of the anisotropic conductive film of the present invention. FIG. 1B is a cross-sectional view of a modified embodiment of the anisotropic conductive film of the present invention. FIG. 1C is a cross-sectional view of a modified embodiment of the anisotropic conductive film of the present invention. FIG. 2 is an explanatory view of the step (A) in the method for producing an anisotropic conductive film of the present invention. FIG. 3A is an explanatory diagram of the step (B) in the method for producing an anisotropic conductive film of the present invention. FIG. 3B is an explanatory diagram of a step (B) in the method for producing an anisotropic conductive film of the present invention. FIG. 4 is an explanatory diagram of step (C) in the method for producing an anisotropic conductive film of the present invention. FIG. 5 is an explanatory diagram when step (D) is performed by method (i) in the method for producing an anisotropic conductive film of the present invention. FIG. 6 is an explanatory diagram of a subsequent process of the process (D) performed by the method (i). FIG. 7 is a cross-sectional view of the anisotropic conductive film obtained in the subsequent step of the step (D) performed by the method (i). FIG. 8 is an explanatory diagram when the step (D) is performed by the method (ii) in the production of the anisotropic conductive film of the present invention. FIG. 9 is an explanatory diagram of the subsequent step of the step (D) performed by the method (ii). FIG. 10 is a cross-sectional view of the anisotropic conductive film obtained in the subsequent step of the step (D) performed by the method (ii).

Hereinafter, an example of the anisotropic conductive film of the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol represents the same or equivalent component.
<< anisotropic conductive film >>

  FIG. 1A is a cross-sectional view of an anisotropic conductive film 1 according to an embodiment of the present invention. In this anisotropic conductive film 1, the first insulating resin layer 2, the intermediate insulating resin layer 4 and the second insulating resin layer 3 are sequentially laminated, and the conductive particles 10 for anisotropic conductive connection are the first A single layer is provided on the surface 2a of the insulating resin layer 2 on the second insulating resin layer 3 side so as to penetrate at least the surface of the intermediate insulating resin layer 4 on the first insulating resin layer 2 side. In contact with the conductive resin layer 4.

<First insulating resin layer 2>
The 1st insulating resin layer 2 which comprises the anisotropic conductive film 1 of this invention is formed with the photopolymerization resin. More specifically, for example, it is formed by photo radical polymerization of a photo radical polymerizable resin layer containing an acrylate compound and a photo radical polymerization initiator. Since the first insulating resin layer 2 is photopolymerized, the conductive particles 10 can be appropriately fixed. That is, even if the anisotropic conductive film 1 is heated at the time of anisotropic conductive connection, the first insulating resin layer 2 is difficult to flow. Therefore, it is greatly caused that the conductive particles 10 are unnecessarily flown by the resin flow and short circuit occurs. Can be suppressed.

In particular, in the anisotropic conductive film 1 of the present example, in the first insulating resin layer 2, the region 2X in which the conductive particles 10 exist on the second insulating resin layer 3 side (that is, the conductive particles 10 and the first conductive film 10). The curing rate of the region between the insulating resin layer 2 and the outer surface 2b is lower than the curing rate of the region 2Y where the conductive particles 10 do not exist on the second insulating resin layer 3 side. It is preferable on the isotropic conductive connection. In the region 2X of the first insulating resin layer 2, the acrylate compound and the photo radical polymerization initiator that have not been photocured may remain. Since the anisotropic conductive film 1 has such a region 2X, the insulating resin in the region 2X can be easily removed at the time of anisotropic conductive connection, so that the conductive particles 10 are in the plane direction of the first insulating resin layer 2. Although it is difficult to move, it is pushed in well in the thickness direction. Therefore, it is possible to improve the conductive particle capture rate, further improve connection reliability, and reduce the occurrence rate of short circuits.
Here, the curing rate is a numerical value defined as a vinyl group reduction ratio, the curing rate of the region 2X of the first insulating resin layer is preferably 40 to 80%, and the curing rate of the region 2Y is preferably 70. ~ 100%.

  On the other hand, it is preferable that there is substantially no difference in curing rate between the first connection layer portions 2X and 2Y in order to stabilize the product quality of the anisotropic conductive film. That is, when the fixing of the conductive particles is promoted in the manufacturing process of the anisotropic conductive film, stable quality can be ensured. In addition, since the anisotropic conductive film is generally manufactured in a long length, wound on a reel, and drawn out from the reel when used for anisotropic conductive connection, the conductive film is conductive from the beginning of winding to the end of winding. By homogenizing the pressure applied to the particles, disorder of the arrangement of the conductive particles can be prevented.

(Acrylate compound)
A conventionally well-known photopolymerizable acrylate can be used as an acrylate compound used as an acrylate unit. 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 polyfunctional (meth) acrylate as at least a part of the acrylic monomer so that the insulating resin layer can be thermally cured at the time of anisotropic conductive connection.

  If the content of the acrylate compound in the first insulating resin layer 2 is too small, the viscosity difference between the first insulating resin layer 2 and the second insulating resin layer 3 tends to be difficult to attach at the time of anisotropic conductive connection. If the amount is too large, curing shrinkage tends to be large and workability tends to decrease.

(Polymerization initiator)
The photopolymerization initiator used for forming the first insulating resin layer can be appropriately selected from known photopolymerization initiators. Examples thereof include photo radical polymerization initiators such as acetophenone photopolymerization initiators, benzyl ketal photopolymerization initiators, and phosphorus photopolymerization initiators.
In addition to the photopolymerization initiator, a thermal radical polymerization initiator may be used. Examples of the thermal radical polymerization initiator include organic peroxides and azo compounds. In particular, an organic peroxide that does not generate nitrogen that causes bubbles can be preferably used.

  If the amount of the photopolymerization initiator used is too small relative to 100 parts by weight of the acrylate compound, the photopolymerization will not proceed sufficiently, and if it is too much, it will cause a reduction in rigidity. More preferably, it is 0.5-15 mass parts.

(Other resins and polymerization initiators)
The first insulating resin layer 2 may contain an epoxy compound and a thermal cation or a thermal anion polymerization initiator or a photo cation or a photoanion polymerization initiator, if necessary. Thereby, delamination strength can be improved. The polymerization initiator used together with the epoxy compound will be described in the second insulating resin layer 3. If necessary, the first insulating resin layer 2 is further used in combination with a film forming resin such as a phenoxy 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. be able to.

  If the layer thickness of the first insulating resin layer 2 is too thin, the conductive particle trapping rate tends to decrease, and if it is too thick, the conduction resistance tends to increase, so that the thickness is preferably 1.0 to 6.0 μm. Preferably it is 2.0-5.0 micrometers.

  The first insulating resin layer 2 is formed on a photopolymerizable resin layer containing a photopolymerizable resin and a photopolymerization initiator by a film transfer method, a mold transfer method, an ink jet method, an electrostatic adhesion method, or the like. Can be carried out by attaching conductive particles to a single layer and irradiating with ultraviolet rays. In this case, the ultraviolet irradiation is preferably performed from the conductive particle side, but may be performed from the side opposite to the conductive particle. In particular, it is preferable to irradiate ultraviolet rays only from the side of the conductive particles because the curing rate of the region 2X of the first insulating resin layer can be suppressed relatively low with respect to the curing rate of the region 2Y.

  The minimum melt viscosity of the first insulating resin layer 2 after the photopolymerization is preferably higher than the minimum melt viscosity of the second insulating resin layer 3, and specifically measured by a rheometer [first insulating resin layer The minimum melt viscosity of 2 (mPa · s)] / [minimum melt viscosity (mPa · s) of the second insulating resin 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 1st insulating resin layer 2, More preferably, it is 500-50000 mPa * s. About the 2nd insulating resin layer 3, Preferably it is 0.1-10000 mPa * s, More preferably, it is 0.5-1000 mPa * s.

<Conductive particles>
The conductive particles 10 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.

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

  As shown in FIG. 1A, the position of the conductive particles 10 in the thickness direction of the first insulating resin layer 2 penetrates the intermediate insulating resin layer 4 without being embedded in the first insulating resin layer 2, It is preferable to bite into the second insulating resin layer 3. That is, in this case, the conductive particles 10 straddle the first insulating resin layer 2 and the second insulating resin layer 3. Since the conductive particles 10 penetrate the intermediate insulating resin layer 4, the deformation of the conductive particles 10 during anisotropic conductive connection can be made uniform, and unnecessary particle deviation can be prevented.

  As shown in FIG. 1A, when the conductive particles 10 penetrate the intermediate insulating resin layer 4 and bite into the second insulating resin layer 3, the intermediate insulating resin layer 4 and the second insulating resin layer are moved to. The degree of biting (that is, the degree of protrusion from the first insulating resin layer 2) is preferably 10 to 90% of the average particle diameter of the conductive particles 10, more preferably from the balance of the conductive particle capture rate and the conductive resistance. Is 20-80%.

  On the other hand, the portion of the conductive particles 10 protruding from the first insulating resin layer 2 may be covered with the intermediate insulating resin layer 4. For example, as shown in FIG. The first insulating resin layer 2 and the intermediate insulating resin layer 4 may be straddled without penetrating the conductive resin layer 4. As described above, even if the intermediate insulating resin layer 4 covers the upper part of the conductive particles 10, the deformation of the conductive particles 10 is difficult to be inhibited in pushing in the anisotropic conductive connection. In this case, the portion of the conductive particles 10 protruding to the first insulating resin layer 2 side is preferably 20% or less, more preferably 10% or less of the particle diameter of the conductive particles.

  Moreover, as a mode in which the portion of the conductive particle 10 protruding from the first insulating resin layer 2 is covered with the intermediate insulating resin layer 4, as shown in FIG. 1C, the first insulating resin layer 2 The conductive particles 10 protruding from the conductive particles 10 may be covered along the ridges of the conductive particles 10 by the intermediate insulating resin layer 4 having a thickness smaller than the diameter of the conductive particles. In the embodiment of FIG. 1C, since the intermediate insulating resin layer 4 is provided following the shape of the conductive particles 10, the deformation inhibition of the conductive particles 10 in pushing in the anisotropic conductive connection can be controlled more precisely.

  On the other hand, when the conductive particles 10 are buried in the first insulating resin layer 2, there is a concern that the deformation of the conductive particles 10 is hindered and the indentation becomes uneven when the electronic component is anisotropically conductively connected. Is not preferable.

<Intermediate insulating resin layer 4>
The intermediate insulating resin layer 4 is provided as a layer that relieves stress applied to the conductive particles when the anisotropic conductive film 1 is wound, unwound, transported, pulled out in the anisotropic conductive connection step, and the like. Yes. When the intermediate insulating resin layer 4 is provided around the conductive particles 10 and the stress accumulated in the conductive particles 10 is relaxed, the conductive particles generated by resin flow or compression of the conductive particles 10 during anisotropic conductive connection The positional deviation in the connection plane direction can be suppressed. Therefore, the anisotropic conductive film 1 of the present invention can realize a good conductive particle capture rate, conduction reliability, and a low short-circuit occurrence rate.

  The thickness of the intermediate insulating resin layer 4 is preferably 1.2 times or less, more preferably 1 time or less, and even more preferably 0.7 times or less the particle diameter of the conductive particles 10. If it is in this range, problems in quality stability such as non-uniform deformation and difficulty in capturing the conductive particles at the bump ends are less likely to occur when the conductive particles 10 are pushed in the anisotropic conductive connection. In addition, when a long anisotropic conductive film is wound on a reel or the like, the pressure applied to the conductive particles can be homogenized, and disorder of the arrangement of the conductive particles can be prevented. In order to make the manufacturing conditions easier, the intermediate insulating resin layer 4 may have substantially the same thickness as the conductive particles 10.

  In order to easily absorb the stress applied to the conductive particles during the anisotropic conductive connection, the intermediate insulating resin layer 4 is formed from a resin that does not contain a polymerization initiator. The resin forming the intermediate insulating resin layer 4 preferably has an elastic modulus comparable to that of the resin component of the other layers, and may be a polymerizable resin. For example, phenoxy resin, epoxy resin, polyolefin resin, polyurethane resin, acrylic resin, or the like can be used.

  The intermediate insulating resin layer 4 preferably contains a filler such as silica in order to effectively suppress the flow of unnecessary conductive particles during anisotropic conductive connection. The filler content in the intermediate insulating resin layer 4 is preferably 0.5 to 20% by mass.

<Second insulating resin layer 3>
The second insulating resin layer 3 is formed of a thermal cation or thermal anion polymerizable resin, a photo cation or photo anion polymerizable resin, a thermal radical polymerizable resin, or a photo radical polymerizable resin. More specifically, it contains an epoxy compound, a thermal cation or thermal anion polymerization initiator or a photo cation or photoanion polymerization initiator, a polymerizable resin layer that polymerizes by heat or light, or an acrylate compound, and a thermal radical. Alternatively, it comprises a polymerizable resin layer that undergoes radical polymerization by heat or light containing a photo radical polymerization initiator.
(Epoxy compound)
As an epoxy compound which forms the 2nd insulating resin layer 3, the compound or resin which has a 2 or more epoxy group in a molecule | numerator is mentioned preferably. These may be liquid or solid.

(Thermal cationic polymerization initiator)
As the thermal cationic polymerization initiator for forming the second insulating resin layer 3, known thermal cationic polymerization initiators for epoxy compounds can be employed. For example, iodonium salts and sulfonium salts that generate an acid by heat , Phosphonium salts, ferrocenes and the like can be used, and in particular, an aromatic sulfonium salt showing a 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 anion polymerization initiator for forming the second insulating resin layer 3, known thermal anion polymerization initiators for epoxy compounds can be employed, for example, aliphatic amine compounds that generate a base by heat. , Aromatic amine compounds, secondary or tertiary amine compounds, imidazole compounds, polymercaptan compounds, boron trifluoride-amine complexes, dicyandiamide, organic acid hydrazides, etc. An encapsulated imidazole compound showing good potential 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)
The acrylate compound that forms the second insulating resin layer 3 can be used by appropriately selecting from the acrylate compounds described for the first insulating resin layer 2.

(Thermal radical polymerization initiator)
In addition, when the acrylate compound is contained in the second insulating resin layer 3, the thermal radical polymerization initiator used together with the acrylate compound is appropriately selected from the thermal radical polymerization initiators described for the first insulating resin layer 2. You can select and use.

  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.

(Layer thickness of the second insulating resin layer 3)
The layer thickness of the second insulating resin layer 3 is preferably 3 to 20 μm, more preferably 5 to 15 μm, from the viewpoint of capturing conductive particles during anisotropic conductive connection.

<< Method for Manufacturing Anisotropic Conductive Film >>
The anisotropic conductive film of the present invention can be produced by performing the following steps (A) to (D).

(Process (A))
As shown in FIG. 2, the conductive particles 10 are arranged in a single layer on the photopolymerizable resin layer 20 formed on the release film 30 as necessary. There is no restriction | limiting in particular as a method of arrange | positioning the electrically-conductive particle 10 in the photopolymerizable resin layer 20 with a single layer, Biaxial stretching operation of the resin film which fixed the electrically-conductive particle of Example 1 of the patent 478938 with the adhesive was carried out. The method of using, the method of using the metal mold | die of Unexamined-Japanese-Patent No. 2010-33793, etc. are employable. The conductive particles 10 are preferably arranged at predetermined intervals in the vertical and horizontal directions. In consideration of the size of the connection target, conduction reliability, insulation, conductive particle capture rate, etc., the two-dimensional closest interparticle distance is preferably about 1 to 100 μm.

(Process (B))
Next, the photopolymerizable resin layer 20 in which the conductive particles 10 are arranged is subjected to a photopolymerization reaction by irradiating with ultraviolet rays (UV), and the first insulating resin layer 2 having the conductive particles 10 fixed on the surface thereof is formed. Form. In this case, preferably, as shown in FIG. 3A, ultraviolet rays (UV) are irradiated from the conductive particle 10 side. As a result, as shown in FIG. 3B, in the first insulating resin layer 2, the region 2 </ b> X where the conductive particles 10 exist on the second insulating resin layer 3 side (the release film 30 side of the first insulating resin layer 2). The curing rate of the first insulating resin layer in the region located between the surface 2b and the conductive particles 10 is made lower than the curing rate of the region 2Y where the conductive particles 10 do not exist on the second insulating resin layer 3 side. be able to. Therefore, it becomes easy to push in the conductive particles 10 at the time of anisotropic conductive connection, and the flow of the conductive particles 10 in the connection plane direction can be suppressed.

(Process (C))
On the other hand, as shown in FIG. 4, the second film formed on the release film 31 with a thermal cation or thermal anion polymerizable resin, a photo cation or photo anion polymerizable resin, a thermal radical polymerizable resin, or a photo radical polymerizable resin. The insulating resin layer 3 is formed by a conventional method.

(Process (D))
The intermediate insulating resin layer 4 is formed on the conductive particle 10 side surface of the first insulating resin layer 2 to which the conductive particles 10 are fixed in the step (B).
This step (D) can be carried out by the following method (i) or (ii).

Method (i)
As shown in FIG. 5, the intermediate insulating resin layer 4 is formed on the surface of the first insulating resin layer 2 to which the conductive particles 10 are fixed in the step (B) on the conductive particle 10 side. More specifically, it contains at least one resin selected from a phenoxy resin, an epoxy resin, a polyolefin resin, a polyurethane resin, and an acrylic resin, preferably containing a filler such as silica. The intermediate insulating resin layer 4 is formed by applying or spraying the coating liquid for forming the resin layer on the surface of the first insulating resin layer 2 on the conductive particle 10 side.
Thereafter, as shown in FIG. 6, the intermediate insulating resin layer 4 and the second insulating resin layer 3 formed in the step (C) are opposed to each other, and thermocompression bonding is performed as shown in FIG. In this case, excessive thermal polymerization is not caused by thermocompression bonding. Then, the anisotropic conductive film 1 of FIG. 1A can be obtained by removing the release films 30 and 31.

Method (ii)
As shown in FIG. 8, the second insulating resin layer 3 formed in the step (C) is coated or sprayed with the same coating liquid for forming an intermediate insulating resin layer as that shown in FIG. An intermediate insulating resin layer 4 is formed on the insulating resin layer 3. Next, as shown in FIG. 9, the intermediate insulating resin layer 4 and the conductive particles 10 on the first insulating resin layer 2 formed in the step (B) are opposed to each other and thermocompression bonded as shown in FIG. . In FIG. 10, the conductive particles 10 do not penetrate the intermediate insulating resin layer 4. By removing the release films 30 and 31, the anisotropic conductive film 1 shown in FIG. 1C can be obtained.

<< Connection structure >>
The anisotropic conductive film 1 of the present invention 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. it can. The connection structure thus obtained is also part of the present invention. The first insulating resin layer 2 side of the anisotropic conductive film is arranged on the second electronic component side such as a flexible substrate, and the second insulating resin layer 3 side is arranged on the first electronic component side such as an IC chip. It is preferable to increase the connection reliability.

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

Examples 1 to 10, Comparative Example 1
Conductive particles are arranged in a single layer according to the operation of Example 1 of Japanese Patent No. 4778938, and a first insulating resin layer and a second insulating resin layer formed according to the composition (parts by mass) shown in Table 1 The anisotropic conductive film of Comparative Example 1 further having an intermediate insulating resin layer, and the conductive particles penetrated through the intermediate insulating resin layer as shown in FIG. 1A. Was made.

  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 liquid is applied to a polyethylene terephthalate film having a thickness of 50 μm so as to have a dry thickness of 3 μm, and is dried in an oven at 80 ° C. for 5 minutes, whereby light that is a precursor layer of the first insulating resin layer A radical polymerizable resin layer was formed.

Next, conductive particles (Ni / Au plated resin particles, AUL704, Sekisui Chemical Co., Ltd.) having an average particle diameter of 4 μm are placed on the surface of the obtained radical photopolymerizable resin layer, and the closest distance between the conductive particles is set. The single layer was arranged in a lattice shape so as to be 4 μm. Further, by irradiating the radical photopolymerizable resin layer from the conductive particle side with ultraviolet rays having a wavelength of 365 nm and an integrated light amount of 4000 mJ / cm ² , a first insulating resin layer having conductive particles fixed on the surface was formed. .
On the other hand, an intermediate insulating resin layer coating was prepared with the formulation shown in Table 1, and this was applied to the first insulating resin layer to which the conductive particles were fixed, thereby forming an intermediate insulating resin layer ( Examples 1 to 10). In Comparative Example 1, the formation of the intermediate insulating resin layer was omitted.

  Moreover, in order to form a 2nd insulating resin layer, the liquid mixture was prepared so that thermosetting resin, the polymerization initiator, etc. might become solid content 50 mass% with ethyl acetate or toluene. 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 insulating resin layer.

  The first insulating resin layer to which the conductive particles are fixed and the second insulating resin layer obtained in this way are laminated so that the conductive particles are on the inner side, and Examples 1 to 10 and An anisotropic conductive film of Comparative Example 1 was obtained.

Example 11
An anisotropic conductive film was obtained in the same manner as in Example 2 except that the photo radical polymerization type resin layer was irradiated with ultraviolet rays from the conductive particle side and the side opposite to the conductive particle by an integrated light amount of 2000 mJ / cm ² .

Example 12
An anisotropic conductive film was obtained in the same manner as in Example 2 except that the thickness of the intermediate insulating resin layer was 5 μm. In this anisotropic conductive film, the conductive particles do not penetrate the intermediate insulating resin layer.

Example 13
An anisotropic conductive film was obtained in the same manner as in Example 11 except that the thickness of the intermediate insulating resin layer was 5 μm. In this anisotropic conductive film, the conductive particles do not penetrate the intermediate insulating resin layer.

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

  About the obtained connection structure sample, as described below, “mounting particle trapping efficiency”, “initial continuity”, “conduction reliability”, “warp”, and “short-circuit occurrence rate” were tested and evaluated. The results are shown in Table 1.

"Mounting particle capture efficiency"
“The number of conductive particles actually captured on the bump of the connection structure sample after heating / pressing” against “the number of conductive particles present on the bump of the connection structure sample before heating / pressing” The percentage (%) of was obtained by the following formula and was defined as the mounting particle trapping efficiency.
The number of conductive particles present on the bumps of the connection structure sample before heating and pressing is determined from the number density of the conductive particles and the bump area of the anisotropic conductive film before heating and pressing of the anisotropic conductive connection. The number of conductive particles present on the bumps of the connection structure sample after calculation and heating and pressing was determined by observation with an optical microscope.
Practically, it is preferably 50% or more.

"Initial conductivity"
The conduction resistance of the connection structure sample was measured.

"Conduction reliability"
The connection 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 in the same manner as the initial conductivity. This conduction resistance is not preferably 5Ω or more from the viewpoint of practical conduction stability of the connected electronic component.

"warp"
The warpage of the surface of the glass wiring board on the side where the IC chip is not mounted at a width of 20 mm corresponding to the width of the IC chip on the opposite side was measured using a three-dimensional side machine (Keyence Co., Ltd.).
The warp is preferably less than 15 μm for practical use.

"Short incidence"
As an IC for evaluating the incidence of short circuit, an IC with a comb tooth TEG pattern with a space of 7.5 μm (outer diameter 1.5 × 13 mm, thickness 0.5 mm, bump specification: gold plating, height 15 μm, size 25 × 140 μm, between bumps Gap 7.5 μm) is prepared, and the anisotropic conductive films of the examples and comparative examples are sandwiched between the evaluation IC for short-circuit occurrence rate and the glass substrate of the corresponding pattern, and the same as the initial conductivity A connected body was obtained by heating and pressing under conditions. Then, a short-circuit occurrence rate of the connected body was calculated by “number of short-circuits / total number of 7.5 μm spaces”. The short-circuit occurrence rate is desirably 100 ppm or less for practical use.

As can be seen from Table 1, the anisotropic conductive films of Examples 1 to 10 showed practically preferable results for all evaluation items of mounting capture efficiency, initial conductivity, conductivity reliability, warpage, and short-circuit occurrence rate. .
The connection structures of Examples 11 and 13 were slightly inferior in mounting particle supplementation efficiency to Example 2, but there were no practical problems, and the initial conductivity, conduction reliability, warpage, and occurrence rate of short circuit were measured. Similar to Example 2, favorable results were shown.
Moreover, in the connection structure of Example 12, the shape of the conductive particles connected to the bumps by microscopic observation was slightly non-uniform compared to Example 2, but the mounting capture efficiency, initial conductivity, and conduction reliability Practically preferable results were shown for all evaluation items of property, warpage, and short-circuit occurrence rate.

  On the other hand, since the anisotropic conductive film of Comparative Example 1 had no intermediate insulating resin layer, the mounting particle capturing efficiency was low and the warp was large.

  The anisotropic conductive film of the present invention includes a first insulating resin layer obtained by photoradical polymerization of a photoradically polymerizable resin layer, a thermal cation or thermal anion polymerizable resin, a photocation or photoanion polymerizable resin, and a thermal radical. A second insulating resin layer formed of a polymerizable resin or a photo-radical polymerizable resin is laminated, and conductive particles are arranged as a single layer on the surface of the first insulating resin layer on the second insulating resin layer side. Therefore, it exhibits excellent initial conductivity, conduction reliability, and low short-circuit occurrence rate due to a good conductive particle capture rate. Further, since the intermediate insulating resin layer is laminated between the first insulating resin layer and the second insulating resin layer so as to surround the conductive particles, the stress applied to the conductive particles is relieved and anisotropic The conductive particle capture rate at the time of conductive connection is further improved. Therefore, the anisotropic conductive film of the present invention is useful for anisotropic conductive connection to a wiring board of an electronic component such as an IC chip. The wiring of electronic components is becoming narrower, and the present invention is particularly useful when the narrowed electronic components are anisotropically conductively connected.

DESCRIPTION OF SYMBOLS 1 Anisotropic conductive film 2 1st insulating resin layer 2a The surface of 1st insulating resin layer 2b The surface of 1st insulating resin layer 2X In the 1st insulating resin layer, it is a conductive particle in the 2nd insulating resin layer side 2Y In the first insulating resin layer, in the first insulating resin layer, there are no conductive particles on the second insulating resin layer side. 3 Second insulating resin layer 4 Intermediate insulating resin layer 10 Conductive particles 20 Photopolymerizable resin layer 30 Release film 31 Release film

Claims (22)

An anisotropic conductive film in which a first insulating resin layer, an intermediate insulating resin layer, and a second insulating resin layer are sequentially laminated,
The first insulating resin layer is formed of a photopolymerization resin;
The second insulating resin layer is formed of a thermal cation or thermal anion polymerizable resin, a photo cation or photo anion polymerizable resin, a thermal radical polymerizable resin, or a photo radical polymerizable resin,
The intermediate insulating resin layer is formed of a resin not containing a polymerization initiator,
Conductive particles for anisotropic conductive connection are arranged as a single layer on the second insulating resin layer side surface of the first insulating resin layer, and the conductive particles are in contact with the intermediate insulating resin layer. the film.   The anisotropic conductive film according to claim 1, wherein the thickness of the intermediate insulating resin layer is 1.2 times or less of the particle diameter of the conductive particles.   The anisotropic conductive film according to claim 1 or 2, wherein the conductive particles penetrate the intermediate insulating resin layer.   The anisotropic conductive film according to claim 1, wherein the intermediate insulating resin layer contains a filler.   The anisotropic conductive film in any one of Claims 1-4 in which an intermediate | middle insulating resin layer contains at least 1 type chosen from a phenoxy resin, an epoxy resin, polyolefin resin, a polyurethane resin, and an acrylic resin.   In the first insulating resin layer, the curing rate of the region where the conductive particles are present on the second insulating resin layer side is lower than the curing rate of the region where the conductive particles are not present on the second insulating resin layer side. Item 6. The anisotropic conductive film according to any one of Items 1 to 5.   The anisotropic conductive film according to claim 1, wherein the first insulating resin layer is obtained by photoradical polymerization of a photoradical polymerizable resin layer containing an acrylate compound and a photoradical polymerization initiator. .   The anisotropic conductive film according to claim 7, wherein the acrylate compound and the photo radical polymerization initiator remain in the first insulating resin layer.   The anisotropic conductive film in any one of Claims 1-8 in which a 1st insulating resin layer contains an acrylate compound and a thermal radical polymerization initiator.   The anisotropic conductive film according to claim 1, wherein the first insulating resin layer contains an epoxy compound and a thermal cation or thermal anion polymerization initiator, or a photo cation or photoanion polymerization initiator.   The second insulating resin layer comprises an epoxy compound, a polymerizable resin containing a thermal cation or thermal anion polymerization initiator or a photo cation or photoanion polymerization initiator, or an acrylate compound, and a thermal radical or photo radical polymerization initiator. The anisotropic conductive film in any one of Claims 1-10 currently formed with the polymeric resin to contain. It is a manufacturing method of the anisotropic conductive film of Claim 1, Comprising: The following processes (A)-(D):
Process (A)
Arranging the conductive particles in a single layer on the radical photopolymerizable resin layer;
Process (B)
A step of causing a photopolymerization reaction by irradiating the photopolymerizable resin layer in which the conductive particles are arranged with ultraviolet rays to form a first insulating resin layer having the conductive particles fixed on the surface;
Process (C)
Forming a second insulating resin layer formed of a thermal cation or thermal anion polymerizable resin, a photo cation or photo anion polymerizable resin, a thermal radical polymerizable resin, or a photo radical polymerizable resin;
Process (D)
Forming an intermediate insulating resin layer formed of a resin not containing a polymerization initiator on the conductive particle side surface of the first insulating resin layer;
Have
(i) An intermediate insulating resin layer is formed on the conductive particle side surface of the first insulating resin layer by performing the step (D) after the step (B), and then the intermediate insulating resin layer and the step (C) Or laminating the second insulating resin layer formed in
(ii) On the second insulating resin layer formed in step (C), an intermediate insulating resin layer formed of a resin not containing a polymerization initiator is formed, and then the intermediate insulating resin layer is formed in the step ( The manufacturing method which laminates | stacks on the electroconductive particle side surface of the 1st insulating resin layer formed in B).   The method for producing an anisotropic conductive film according to claim 12, wherein the thickness of the intermediate insulating resin layer is 1.2 times or less of the particle diameter of the conductive particles.   The method for producing an anisotropic conductive film according to claim 12 or 13, wherein the intermediate insulating resin layer contains a filler.   The method for producing an anisotropic conductive film according to claim 12, wherein the intermediate insulating resin layer contains at least one selected from a phenoxy resin, an epoxy resin, a polyolefin resin, a polyurethane resin, and an acrylic resin.   The method for producing an anisotropic conductive film according to claim 12, wherein in the step (B), the photopolymerizable resin layer is irradiated with ultraviolet rays from the conductive particle side.   The method for producing an anisotropic conductive film according to claim 12, wherein the photopolymerizable resin forming the first insulating resin layer contains an acrylate compound and a radical photopolymerization initiator.   The method for producing an anisotropic conductive film according to any one of claims 12 to 17, wherein the photopolymerizable resin forming the first insulating resin layer further contains a thermal radical polymerization initiator.   The method for producing an anisotropic conductive film according to claim 12, wherein the photopolymerizable resin forming the first insulating resin layer contains an epoxy compound and a photocation or photoanion polymerization initiator.   The method for producing an anisotropic conductive film according to claim 12, wherein the first insulating resin layer further contains a thermal cation or a thermal anionic polymerization initiator.   The second insulating resin layer contains an epoxy compound and a polymerizable resin containing a thermal cation or a thermal anion polymerization initiator or a photo cation or a photoanion polymerization initiator, or an acrylate compound and a thermal radical or a photo radical polymerization initiator. The manufacturing method of the anisotropic conductive film in any one of Claims 12-20 currently formed with the polymerizable resin to perform.   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 1-11.

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