HK1240407A1 - Anisotropic electrically-conductive film, method for manufacturing same, and connection structure - Google Patents

Description

Anisotropic conductive film, method for producing same, and connection structure

Technical Field

The present invention relates to an anisotropic conductive film in which metal particles and a flux are present in contact or proximity in the film.

Background

It has been proposed to use an anisotropic conductive film in which conductive particles or the like for forming a nickel/gold plating layer on the surface of a resin core are dispersed in an insulating adhesive composition when an IC chip is mounted on a substrate (patent document 1). In this case, the conductive particles are crushed between the terminals of the IC chip and the terminals of the substrate, or the conductive particles are cut into the terminals to secure conduction, and the insulating adhesive composition fixes the IC chip, the substrate, and the conductive particles.

However, since the conductive particles do not form a metal bond with the terminals of the IC chip or the terminals of the substrate, there is a problem that conduction reliability is lowered when a connection structure in which the IC chip is connected to the substrate by the anisotropic conductive film is stored in a high-temperature high-pressure or high-temperature high-humidity environment.

Therefore, as the conductive particles of the anisotropic conductive film, solder particles that form metal bonds with copper or the like at a lower temperature than metal such as copper or aluminum that is commonly used as a terminal material of an IC chip can be considered.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open No. 2014-60150.

Disclosure of Invention

Problems to be solved by the invention

In the case of connecting terminals with solder, it is generally indispensable to use flux for removing an oxide film on the solder surface. Therefore, it is conceivable that the surfaces of the solder particles are coated with the flux, but the solder particles coated with the flux are likely to aggregate in the insulating adhesive composition. Therefore, there is a problem that short circuits are likely to occur when anisotropic conductive films containing such solder particles as anisotropic conductive connection particles are used for anisotropic conductive connection. In addition, it is conceivable that a flux is dissolved or dispersed in the insulating adhesive composition, but in order to clean the surface of the solder particles to a desired level, a large amount of flux must be blended in the insulating adhesive composition, and there arises a problem that the terminal corrosion by the flux progresses. This problem similarly occurs in an anisotropic conductive film containing metal particles having an oxide film formed thereon as conductive particles for anisotropic conductive connection.

The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide an anisotropic conductive film in which metal particles such as solder particles having an oxide film on the surface are used as conductive particles for anisotropic conductive connection, which can suppress the occurrence of short circuits and can realize high conduction reliability.

Means for solving the problems

The present inventors have found that in an anisotropic conductive film in which metal particles such as solder particles having an oxide film on the surface are used as conductive particles for anisotropic conductive connection, the anisotropic conductive film may be regularly arranged in a plan view in order to suppress the occurrence of short circuits, the metal particles need not be randomly dispersed in an insulating adhesive composition, and a flux may be present in the film in contact with or close to the metal particles in order to achieve high conduction reliability, and thus the present invention has been completed.

That is, the present invention provides an anisotropic conductive film comprising metal particles in an insulating film, wherein the metal particles are regularly arranged in a plan view, and the metal particles are arranged so that a solder is in contact with or close to at least one of the end portions of the metal particles on the surface side of the anisotropic conductive film or the end portions of the metal particles on the back side of the anisotropic conductive film.

The present invention also provides a method for producing the anisotropic conductive film, including the following steps (a) to (C):

(A) disposing flux at least at the bottom of a recess of a transfer mold having the regularly arranged recesses;

(B) disposing metal particles in the recess where the flux is disposed; and

(C) and a step of bringing the insulating film into contact with the metal particles from the side of the recess of the transfer mold, and transferring the metal particles to the insulating film by applying heat and pressure. The production method preferably further comprises step (D):

(D) and a step of thermocompression bonding another insulating film to the metal particle transfer surface of the insulating film to which the metal particles are transferred.

The present invention also provides another method for producing the anisotropic conductive film, comprising the following steps (a) to (d):

(a) disposing metal particles in a recess of a transfer mold having regularly arranged recesses;

(b) disposing a flux on a concave portion forming surface of a transfer mold on which metal particles are disposed;

(c) a step of bringing the insulating film into contact with the flux arrangement surface side of the transfer mold, and applying heat and pressure to transfer the metal particles to the insulating film; and

(d) and a step of thermocompression bonding another insulating film to the metal particle transfer surface of the insulating film to which the metal particles are transferred.

Further, the present invention provides a connection structure in which the anisotropic conductive film disposed between the terminal of the 1 st electronic component and the terminal of the 2 nd electronic component is heated and pressed to anisotropically conductively connect the 1 st electronic component and the 2 nd electronic component.

Effects of the invention

In the anisotropic conductive film of the present invention having metal particles in the insulating film, the metal particles are regularly arranged in a plan view, and therefore, when the anisotropic conductive film is applied to anisotropic conductive connection, occurrence of short circuit can be suppressed. Further, since the flux is disposed so as to be in contact with or close to at least one of the end portion of the metal particles on the surface of the anisotropic conductive film or the end portion of the metal particles on the back surface of the anisotropic conductive film, the oxide film on the surface of the metal particles can be removed at the time of anisotropic conductive connection, and high conduction reliability can be achieved.

Drawings

Fig. 1A is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 1B is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 1C is a cross-sectional view of the anisotropic conductive film of the present invention shown in FIG. 1C.

FIG. 2A is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 2B is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 2C is a cross-sectional view of the anisotropic conductive film of the present invention shown in FIG. 2C.

FIG. 3 is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 4 is a cross-sectional view 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 a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 7A is a process explanatory view of the method for manufacturing an anisotropic conductive film of the present invention.

FIG. 7B is a process explanatory view of the method for manufacturing an anisotropic conductive film of the present invention, shown in FIG. 7B.

FIG. 7C is a process explanatory view of the method for manufacturing an anisotropic conductive film of the present invention.

Fig. 8A is a process explanatory view of the method for manufacturing an anisotropic conductive film of the present invention.

FIG. 8B is a process explanatory view of the method for manufacturing an anisotropic conductive film of the present invention.

Fig. 8C and 8C are process explanatory views of the method for manufacturing an anisotropic conductive film according to the present invention.

FIG. 8D is a process explanatory view of the method for manufacturing an anisotropic conductive film of the present invention.

Fig. 9A is a process explanatory view of the method for manufacturing an anisotropic conductive film of the present invention.

Fig. 9B is a process explanatory view of the method for manufacturing an anisotropic conductive film of the present invention.

Fig. 9C is a process explanatory view of the method for manufacturing an anisotropic conductive film of the present invention.

Fig. 9D is a process explanatory view of the method for manufacturing an anisotropic conductive film of the present invention.

FIG. 10A is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 10B is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 10C is a cross-sectional view of the anisotropic conductive film of the present invention shown in FIG. 10C.

FIG. 10D is a cross-sectional view of the anisotropic conductive film of the present invention.

Fig. 11A is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 11B is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 11C is a cross-sectional view of the anisotropic conductive film of the present invention.

FIG. 11D is a cross-sectional view of the anisotropic conductive film of the present invention.

Fig. 12A is a process explanatory view of the method for manufacturing an anisotropic conductive film of the present invention.

Fig. 12B is a process explanatory view of the method for manufacturing an anisotropic conductive film of the present invention.

Fig. 12C is a process explanatory view of the method for manufacturing an anisotropic conductive film of the present invention.

Fig. 12D is a process explanatory view of the method for manufacturing an anisotropic conductive film of the present invention.

Detailed Description

< Anisotropic conductive film >

Specific examples of the present invention will be described below with reference to the drawings.

As shown in fig. 1A, 1B, and 1C, the anisotropic conductive film 10 of the present invention is an anisotropic conductive film having metal particles 2 in an insulating film 1. Although not shown, the metal particles are regularly arranged in a plan view. Here, the regular array is not particularly limited as long as it is a regular array, but preferable examples thereof include an orthorhombic array, a hexagonal array, a square array, a rectangular array, and a parallel lattice array. Among them, hexagonal lattice arrangement which can be most densely packed is preferable.

The insulating film 1 can be selected from insulating films used for conventionally known anisotropic conductive films and used as appropriate. Examples thereof include thermoplastic acrylic or epoxy resin films, thermosetting or photocurable acrylic or epoxy resin films, and the like. The thickness of the insulating film is usually 10 to 40 μm. The insulating film 1 may be a film at least in the state of the anisotropic conductive film, and may be a high-viscosity liquid at the time of manufacturing the film.

Further, an insulating filler such as silica fine particles, alumina, or aluminum hydroxide may be added to the insulating film 1 as necessary. The size of the insulating filler is preferably 0.01 to 8 μm in average particle diameter. The amount of the insulating filler is preferably 3 to 40 parts by mass per 100 parts by mass of the resin forming the insulating film. This makes it easy to ensure the conduction reliability after the anisotropic conductive connection.

The metal particles 2 are used as metal particles for anisotropic conductive connection in an anisotropic conductive film, and can be appropriately selected from particles having an oxide film formed on the surface thereof. Among them, solder particles having an average particle diameter of 10 to 40 μm when measured by an image-type particle size distribution meter can be preferably used.

In the anisotropic conductive film of the present invention, the flux 3 is disposed so as to be in contact with or close to at least one of the end portion of the metal particles on the surface side of the anisotropic conductive film or the end portion on the back side of the anisotropic conductive film. For example, in the embodiment shown in fig. 1A, the flux 3 is disposed so as to be in contact with the front-side end portion 2a of the anisotropic conductive film of the metal particles 2. In the embodiment shown in fig. 1B, the flux 3 is disposed so as to contact the rear-side end 2B of the anisotropic conductive film of the metal particles 2. In the embodiment shown in fig. 1C, the flux 3 is disposed so as to contact each of the end portion 2a on the front surface side of the anisotropic conductive film and the end portion 2b on the back surface side of the anisotropic conductive film of the metal particle 2. As in these arrangements, when the metal particles 2 and the flux 3 are brought into contact with each other, the oxide film on the surface of the metal particles 2 is removed by the flux 3 due to heat at the time of anisotropic conductive connection, and a metal bond is formed between the metal particles 2 and a terminal to be connected.

The proximity of the metal particles 2 to the flux 3 means that they are separated by a minimum distance of less than 2 μm. If the distance is longer than this, there is a concern that contact between the two will be hindered during anisotropic conductive connection.

The metal particles 2 and the flux 3 can be disposed in close proximity to each other by, for example, mixing the flux and an insulating filler. This is because the insulating filler functions as a spacer for separating the metal particles 2 from the flux 3. Examples of such an insulating filler include fumed silica (FumedSilica) having an average primary particle diameter of 1 to 1000 nm.

The relationship between the amount of the metal particles 2 and the amount of the flux 3 in contact with or close to the metal particles is such that the thickness of the flux 3 is 0.001 to 0.4 times or less the average particle diameter of the metal particles 2. Within this range, the surface of the metal particles 2 can be cleaned, and the anisotropic conductive connection material is not corroded.

When the flux 3 is disposed in contact with or in close proximity to the metal particles 2, the flux may be diluted (preferably, a dilution ratio: 0.1 to 40 wt% with respect to the solvent) in a solvent, and then applied to a transfer mold or an insulating film to which the metal particles are attached by a known coating method as described later, and dried as necessary.

Further, the flux 3 removes the oxide film on the surface of the metal particle 2 under heating conditions at the time of anisotropic conductive connection. As the flux 3, a known flux corresponding to the material of the metal particles 2 can be applied.

In the embodiments of fig. 1A to 1C, the metal particles 2 are present isolated from the front surface or the back surface of the insulating film 1, but may be exposed on the front surface or the back surface of the insulating film 1. For example, as for the embodiment of fig. 1A, as shown in fig. 2A, the end portion opposite to the end portion 2A of the metal particle 2 may be deformed so as to be exposed on the back surface of the insulating film 1. In this case, the flux 3 is disposed so as to contact the end 2 a. In the embodiment of fig. 1B, the flux 3 disposed in contact with the end portion 2B may be deformed so as to be exposed as shown in fig. 2B. The approach of fig. 1C may also be modified as in fig. 2C.

Although the insulating film 1 is a single layer in fig. 1A to 1C and fig. 2A to 2C, the insulating film 1 may have a 2-layer structure (1A and 1 b) and the metal particles 2 may be disposed between the layers as shown in fig. 3. With such a 2-layer structure, the degree of freedom in manufacturing can be increased.

As shown in fig. 4, the anisotropic conductive film 10 of the present invention further includes a mode in which a part of the surface of the metal particle 2 is not in contact with the flux 3. In fig. 4, the surface portion of the metal particle 2 not in contact with the flux 3 faces the side surface of the film, but may face the front surface side or the back surface side of the film. In particular, as shown in fig. 5, it is preferable that the surface portion of the metal particle 2 not in contact with the flux 3 is disposed on the opposite side of the surface portion of the metal particle in contact with the flux.

As shown in fig. 6, the flux 3 may be disposed between the adjacent metal particles 2 in the planar direction of the anisotropic conductive film 10 of the present invention. In such an anisotropic conductive film 10, the flux 3 disposed between the adjacent metal particles 2 is pulled by the metal particles 2 during anisotropic conductive connection, so that the surfaces of the metal particles can be cleaned with a sufficient amount of flux, and interlayer peeling of the insulating film having a 2-layer structure does not occur. In this case, it is preferable that the amount of flux per unit area disposed at least at one of the anisotropic conductive film front side end portion 2a and the anisotropic conductive film back side end portion 2b of the metal particle 2 is larger than the amount of flux per unit area disposed between the adjacent metal particles 2.

< method for producing anisotropic conductive film >

The anisotropic conductive film of the present invention can be produced by a production method having the following steps (a) to (C).

(Process (A))

First, as shown in fig. 7A to 7C, the flux 3 is disposed at least on the bottom of the recessed portion 50 of the transfer mold 100 having the recessed portions 50 arranged regularly. Specifically, as shown in fig. 7A, the flux 3 may be disposed only at the bottom of the recess 50, or as shown in fig. 7B, the flux 3 may be disposed on the entire inner wall surface including the bottom of the recess 50. As shown in fig. 7C, the flux 3 may be disposed on the surface between the bottom of the recess 50 and the adjacent recess 50 of the transfer body 100. In the case of fig. 7C, the flux amount per unit area of the bottom of the recess 50 is preferably made larger than the flux amount per unit area of the surface between the adjacent recesses 50.

As the transfer mold 100, a mold manufactured by a known method can be used. For example, a metal plate may be processed to prepare a master, and the master may be coated with a curable resin composition and cured. Specifically, a flat metal plate is cut, a transfer master is further prepared in which projections corresponding to the recesses are formed, a curable resin composition constituting the transfer is applied to the projection-forming surface of the master, cured, and then pulled away from the master to obtain the transfer.

As a method of disposing the flux 3 on at least the bottom of the recess 50, a known method may be employed, for example, a method of applying the flux on the entire surface of the transfer mold by a screen printing method and scraping the flux on the outermost surface with a squeegee as necessary.

(Process (B))

Next, as shown in fig. 8A to 8C, the metal particles 2 are disposed in the concave portions 50 where the flux 3 is disposed. As a method of disposing the metal particles 2, a known method can be employed. For example, the metal particles may be dispersed on the surface of the transfer mold, and the metal particles present on the surface of the transfer mold other than the recessed portions may be removed by blowing or cutting. Further, the metal particles may be supplied to the concave portion one by a micro dispenser.

Further, as shown in fig. 8A, after supplying the metal particles to the concave portion of the transfer mold, the flux 3 may be disposed on the surface of the metal particles 2 by a method of the step as shown in fig. 8D.

(Process (C))

Next, as shown in fig. 9A to 9D, the insulating film 1 is brought into contact with the metal particles 2 from the recessed portion 50 side of the transfer mold 100 (fig. 8A to 8D) in fig. 8A to 8D in which the metal particles 2 are arranged, and heated and pressurized, thereby transferring the metal particles 2 to the insulating film 1. In this state, if the insulating film 1 is wound around a roll (roll), the anisotropic conductive film 10 of fig. 10A can be obtained from the system of fig. 9A, the anisotropic conductive film 10 of fig. 10B can be obtained from the system of fig. 9B, the anisotropic conductive film 10 of fig. 10C can be obtained from the system of fig. 9C, and the anisotropic conductive film 10 of fig. 10D can be obtained from the system of fig. 9D.

In the manufacturing method of the present invention, it is preferable that the following step (D) is further provided in order to form the insulating film into a 2-layer structure.

(Process (D))

That is, by thermocompression bonding another insulating film to the metal particle transfer surface of the insulating film (fig. 9A to 9D) to which the metal particles are transferred, the anisotropic conductive film 10 of fig. 11A having the insulating film 1 (1A and 1B) having the 2-layer structure can be obtained from the system of fig. 9A, the anisotropic conductive film 10 of fig. 11B having the insulating film 1 (1A and 1B) having the 2-layer structure can be obtained from the system of fig. 9B, the anisotropic conductive film 10 of fig. 11C having the insulating film 1 (1A and 1B) having the 2-layer structure can be obtained from the system of fig. 9C, and the anisotropic conductive film 10 of fig. 11D having the insulating film 1 (1A and 1B) having the 2-layer structure can be obtained from the system of fig. 9D.

The anisotropic conductive film of the present invention can also be produced by another production method including the following steps (a) to (c).

(Process (a))

First, as shown in fig. 12A, the metal particles 2 are disposed in the recesses 50 of the transfer mold 200 having the regularly arranged recesses 50.

(Process (b))

Next, as shown in fig. 12B, the flux 3 is disposed on the concave portion forming surface of the transfer mold 200 on which the metal particles 2 are disposed.

(step (c))

Next, as shown in fig. 12C, the insulating film 1a is brought into contact with the concave portion 50 side of the transfer mold 200 in which the metal particles 2 are arranged, and heated and pressurized, thereby transferring the metal particles 2 to the insulating film 1a together with the flux 3.

(Process (d))

Next, as shown in fig. 12D, another insulating film 1b is thermocompression bonded to the metal particle transfer surface of the insulating film 1a to which the metal particles 2 are transferred. This makes it possible to obtain an anisotropic conductive film 10 in which the flux 3 is disposed between the 2-layer insulating film 1a and the other insulating film 1 b.

< connecting Structure >

The anisotropic conductive film of the present invention is disposed between a terminal of a 1 st electronic component such as an IC chip or a semiconductor wafer and a terminal of a 2 nd electronic component such as a wiring board or a semiconductor wafer, and is useful for manufacturing a connection structure in which the 1 st electronic component and the 2 nd electronic component are anisotropically and electrically connected by heating and pressing. Such a connection structure is also an embodiment of the present invention.

Examples

The present invention will be specifically described below with reference to examples.

Example 1

A nickel plate having a thickness of 2mm was prepared, and columnar projections (outer diameter 25 μm and height 20 μm) were formed in a square lattice pattern to be used as a transfer master. The distance between the centers of the adjacent projections was 40 μm. Thus, the density of the projections was 625/mm²。

The obtained master plate of the transfer body was coated with a photopolymerizable resin composition containing 60 parts by mass of a phenoxy resin (YP-50, shinikagaku corporation), 29 parts by mass of an acrylic resin (M208, toyama synthesis corporation), and 2 parts by mass of a photopolymerization initiator (IRGACURE 184, BASFJAPAN corporation) so that the dry thickness became 30 μ M, dried at 80 ℃ for 5 minutes, and irradiated with 1000mJ light by a high-pressure mercury lamp, thereby producing the transfer body.

To the transfer mold peeled from the master of the transfer mold, a flux (ESR-250T 4, manufactured by seikagaku corporation) diluted to 5 wt% with toluene was applied by a squeegee so that the thickness of the flux in the concave portion after drying became 1 μm, and the flux on the surface of the transfer mold was scraped off.

In this transfer mold, solder particles (fine solder powder, Mitsui metal mining industry (Ltd)) having an average particle diameter of 20 μm were dispersed, and then the recesses were filled with the solder particles by air blowing.

An insulating film (a film composed of 60 parts by mass of phenoxy resin (YP-50, new day ferro-gold chemical), 40 parts by mass of epoxy resin (jER 828, mitsubishi chemical), and 2 parts by mass of cationic curing agent (SI-60L, shin-chan chemical industries, ltd)) having a thickness of 20 μm was pressed against the solder particle-adhering surface of the transfer mold to which the conductive particles adhered at a temperature of 50 ℃ and a pressure of 0.5MPa, thereby transferring the solder particles to the insulating film.

The solder particles of the obtained insulating film were transferred to a surface, and another insulating film having a thickness of 5 μm (a film composed of 60 parts by mass of phenoxy resin (YP-50, new day ferro-gold chemical corporation)), 40 parts by mass of epoxy resin (jER 828, mitsubishi chemical corporation), and 2 parts by mass of cationic curing agent (SI-60L, shin-shi chemical industry corporation)) was stacked thereon at a temperature of 60 ℃ and a pressure of 2MPa to obtain an anisotropic conductive film.

Example 2

A transfer mold similar to that of example 1 was prepared, solder particles (fine solder powder, mitsui metal mining industry (ltd)) having an average particle size of 20 μm were dispersed in the transfer mold, and then the recesses were filled with the solder particles by air blowing.

Flux diluted to 20 wt% with toluene was applied to the surface of the transfer mold filled with solder particles by a squeegee so that the thickness of the dried flux became 1 μm (ESR-250T 4, king of metals industries).

An insulating film (a film composed of 60 parts by mass of phenoxy resin (YP-50, shiniki chemical corporation)), 40 parts by mass of epoxy resin (jER 828, mitsubishi chemical corporation), and 2 parts by mass of cationic curing agent (SI-60L, shinkanji chemical corporation)) having a thickness of 20 μm was supported on the flux surface, and the solder particles were transferred to the insulating film by pressing at a temperature of 50 ℃ and a pressure of 0.5 MPa.

The solder particles of the insulating film thus obtained were transferred to a surface, and another insulating film having a thickness of 5 μm (a film composed of 60 parts by mass of phenoxy resin (YP-50, new day ferro-gold chemical corporation)), 40 parts by mass of epoxy resin (jER 828, mitsubishi chemical corporation), and 2 parts by mass of cationic curing agent (SI-60L, shin-shi chemical industry corporation)) was stacked thereon, and the resultant was laminated at a temperature of 60 ℃ and a pressure of 2MPa to obtain an anisotropic conductive film.

Comparative example 1

Example 1 was repeated except that no flux was used to obtain an anisotropic conductive film.

Example 3

A transfer mold similar to example 1 was prepared, and solder was disposed on the bottom of the concave portion of the transfer mold in the same manner as in example 1, and then the concave portion was filled with solder particles. To the surface of the transfer mold, again, a flux (ESR-250T 4, Kilo metals industries, Ltd.) diluted to 5 wt% with toluene was applied by a squeegee. Then, the same operation as in example 1 was repeated to obtain an anisotropic conductive film. The coating thickness after drying of the flux was 1 μm at the film interface side end of the solder particles and less than 1 μm between the solder particles.

Example 4

Example 1 was repeated to obtain an anisotropic conductive film, except that the dilution of the flux (ESR-250T 4, king of metals industries, ltd.) with toluene in example 1 was changed from 5 wt% to 10 wt%, and the coating thickness after drying was 2 μm.

(evaluation)

Using the obtained anisotropic conductive film, an IC chip for test having gold bumps of 100. mu. m.times.100. mu. m.times.15 μm (height) size was formed on a glass epoxy substrate for IC mounting (material: FR 4) by anisotropic conductive connection under the conditions of a temperature of 180 ℃, a pressure of 40mPa, and a heating and pressing time of 20 seconds, thereby obtaining a connection structure. The obtained connection structure was measured for an initial on-resistance value, an on-resistance value after a high pressure retort test (PCT) (experimental conditions: standing for 200 hours in an environment of 121 ℃ C. and 2 atm), and an on-resistance value after a high temperature and high humidity bias test (experimental conditions: applying 50v in an environment of 85 ℃ C. and 85% humidity). The obtained results are shown in table 1.

In addition, in terms of practicality, it is necessary to make the initial on resistance value less than 1 Ω, and to make the on resistance value after PCT and after the high-temperature and high-humidity bias test less than 15 Ω.

[ Table 1]

Conduction resistance value (omega)	Comparative example 1	Example 1	Example 2	Example 3	Example 4
						Initial	0.1	0.1	0.1	0.1	0.1
After PCT	120	5	5	5	5
						After the high temperature and high humidity bias test	80	5	10	10	7

As is clear from table 1, the anisotropic conductive films of examples 1 to 4 have good results for all the evaluation items because the solder particles and the flux are disposed in contact with each other in the film. In contrast, in comparative example 1, the solder particles and the flux were not disposed in contact with each other in the film, and therefore the on-resistance value was significantly increased after the PCT experiment and the high-temperature high-humidity bias experiment.

Example 5

The procedure of example 1 was repeated except that a film composed of 60 parts by mass of phenoxy resin (YP-50, shiniki chemical corporation), 40 parts by mass of epoxy resin (jER 828, mitsubishi chemical corporation), 10 parts by mass of fumed silica (R200, japan AEROSIL), and 2 parts by mass of cationic curing agent (SI-60L, shin chemical industry corporation) was used as an insulating film having a thickness of 20 μm to which solder particles were transferred, to obtain an anisotropic conductive film. The obtained anisotropic conductive film obtained was good in any of the evaluation items, as in the anisotropic conductive film of example 1.

Industrial applicability

The anisotropic conductive film of the present invention is useful when an IC chip is mounted on a wiring board, because it suppresses occurrence of short circuits in a connection structure obtained by anisotropic conductive connection using the anisotropic conductive film, and suppresses not only the initial on-resistance value but also the on-resistance value after PCT and after a high-temperature and high-humidity bias test.

Description of the reference symbols

1. 1a, 1b insulating films; 2 metal particles; 2a, 2b metal particles on the front or back side end of the anisotropic conductive film; 3, welding flux; 10 an anisotropic conductive film; a recess of a 50-revolution stamp; 100. 200 revolutions of the die.

Claims (12)

1. In the anisotropic conductive film, the metal particles are regularly arranged in a plan view, and a flux is disposed so as to be in contact with or close to at least one of an end portion of the metal particles on the surface of the anisotropic conductive film or an end portion of the metal particles on the back surface of the anisotropic conductive film.

2. The acf of claim 1, wherein the metal particles are solder particles.

3. The anisotropic conductive film according to claim 1 or 2, wherein the insulating film has a 2-layer structure, and metal particles are disposed between the layers.

4. The anisotropic conductive film according to any of claims 1 to 3, wherein a part of the surface of the metal particles is not in contact with a flux.

5. The anisotropic conductive film according to any of claims 1 to 4, wherein a surface portion of the metal particles that is not in contact with the flux is disposed on an opposite side of a surface portion of the metal particles that is in contact with the flux.

6. The anisotropic conductive film according to any of claims 1 to 5, wherein a flux is disposed between adjacent metal particles in a plane direction of the anisotropic conductive film.

7. The anisotropic conductive film according to claim 6, wherein the flux disposed between the adjacent metal particles is disposed between layers of the insulating film having a 2-layer structure.

8. The anisotropic conductive film according to claim 6 or 7, wherein an amount of the flux per unit area disposed at least one of the end portion of the metal particles on the surface of the anisotropic conductive film or the end portion of the metal particles on the back surface of the anisotropic conductive film is larger than an amount of the flux per unit area disposed between the adjacent metal particles.

9. The method for manufacturing an anisotropic conductive film according to claim 1, comprising the following steps (a) to (C):

(A) disposing flux at least at the bottom of a recess of a transfer mold having the regularly arranged recesses;

(B) disposing metal particles in the recess where the flux is disposed; and

(C) and a step of bringing the insulating film into contact with the metal particles from the side of the recess of the transfer mold, and transferring the metal particles to the insulating film by applying heat and pressure.

10. The production method according to claim 9, further comprising a step (D):

(D) and a step of thermocompression bonding another insulating film to the metal particle transfer surface of the insulating film to which the metal particles are transferred.

11. The method for manufacturing an anisotropic conductive film according to claim 1, comprising the following steps (a) to (d):

(a) disposing metal particles in a recess of a transfer mold having regularly arranged recesses;

(b) disposing a flux on a concave portion forming surface of a transfer mold on which metal particles are disposed;

(c) a step of bringing the insulating film into contact with the flux arrangement surface side of the transfer mold, and applying heat and pressure to transfer the metal particles to the insulating film; and

(d) and a step of thermocompression bonding another insulating film to the metal particle transfer surface of the insulating film to which the metal particles are transferred.

12. A connection structure, wherein the anisotropic conductive film according to claim 1, which is arranged between a terminal of a 1 st electronic component and a terminal of a 2 nd electronic component, is heated and pressed to anisotropically connect the 1 st electronic component and the 2 nd electronic component.