HK1240407B

HK1240407B - Anisotropic electrically-conductive film, method for manufacturing same, and connection structure

Info

Publication number: HK1240407B
Application number: HK17113546.3A
Authority: HK
Inventors: Kenichi Haga; Tomoyuki Ishimatsu; Yasushi Akutsu
Original assignee: Dexerials Corporation
Priority date: 2015-01-13
Filing date: 2016-01-05
Publication date: 2020-07-10

Abstract

This anisotropic electrically-conductive film, which contains metal particles, such as solder particles having an oxide film on the surface, as electrically-conductive particles for use in anisotropic electrically-conductive interconnections, is provided with metal particles within an insulating film, the metal particles being regularly arrayed in plan view. The metal particles are arranged such that at least one end part from the anisotropic electrically-conductive film front surface-side end thereof and the anisotropic electrically-conductive film back surface-side end thereof is in contact with, or nearby, a flux. In preferred practice the metal particles are solder particles. In preferred practice, the insulating film has a two-layer structure, and the metal particles are arranged between the layers.

Description

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

Technical Field

The present invention relates to an anisotropic conductive film in which metal particles and solder are in contact with or close to each other within the film.

Background Art

A proposal has been made to use an anisotropic conductive film in which conductive particles, such as those forming nickel/gold plating on the surface of a resin core, are dispersed in an insulating adhesive composition when mounting an IC chip on a substrate (Patent Document 1). In this case, the conductive particles are crushed between the IC chip terminals and the substrate terminals, or the conductive particles are cut into by each terminal, ensuring electrical continuity. The insulating adhesive composition also secures the IC chip, substrate, and conductive particles.

However, since the conductive particles do not form a metallic bond with the terminals of the IC chip or the terminals of the substrate, there is a problem of reduced conduction reliability when the connection structure obtained by connecting the IC chip to the substrate using an anisotropic conductive film is stored in a high temperature and high pressure or high temperature and high humidity environment.

Therefore, it is conceivable to use solder particles as the conductive particles of the anisotropic conductive film. These solder particles form a metallic bond with copper or the like at a lower temperature than with metals such as copper and aluminum commonly used as terminal materials for IC chips.

Prior Art Literature

Patent Literature

Patent Document 1: Japanese Patent Application Laid-Open No. 2014-60150.

Summary of the Invention

Problems to be solved by the invention

In addition, when connecting terminals with solder, it is generally necessary to use flux to remove the oxide film on the solder surface. Therefore, it is possible to coat the surface of the solder particles with flux, but the solder particles coated with flux are easily condensed in the insulating adhesive composition. Therefore, when anisotropic conductive film containing particles of such solder particles as anisotropic conductive connection is used for anisotropic conductive connection, there is a problem of easy short circuit. In addition, it is possible to dissolve or disperse flux in the insulating adhesive composition, but in order to clean the surface of the solder particles to the desired level, a large amount of flux must be coordinated with the insulating adhesive composition, and the problem of terminal corrosion caused by the flux occurs instead. This problem also occurs in the anisotropic conductive film containing conductive particles used for anisotropic conductive connection using metal particles formed with oxide film.

The present invention aims to solve the above problems of the prior art and to suppress the occurrence of short circuits and achieve high conduction reliability in an anisotropic conductive film using metal particles such as solder particles having an oxide film on the surface as conductive particles for anisotropic conductive connection.

Solutions to Problems

The present inventors have discovered 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, in order to suppress the occurrence of short circuits, the anisotropic conductive film can be arranged regularly when viewed from above, without the need to randomly disperse the metal particles in an insulating adhesive composition. Furthermore, in order to achieve high conduction reliability, the solder and the metal particles can be present in the film in contact with or close to each other, thereby completing the present invention.

That is, the present invention provides an anisotropic conductive film, which has metal particles in an insulating film. In the anisotropic conductive film, the metal particles are regularly arranged when viewed from above, and are arranged in a manner such that a flux is in contact with or close to at least one of the ends of the metal particles on the surface side of the anisotropic conductive film or the back side of the anisotropic conductive film.

Furthermore, the present invention provides a method for producing the anisotropic conductive film, comprising the following steps (A) to (C):

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

(B) a step of placing metal particles in the recessed portion where the flux is placed; and

(C) A step of bringing the insulating film into contact with the concave portion of the transfer mold on which the metal particles are arranged and applying heat and pressure to transfer the metal particles to the insulating film. This production method preferably further comprises a step (D):

(D) A step of thermocompression bonding another insulating film to the metal particle transferred surface of the insulating film to which the metal particles have been transferred.

Furthermore, the present invention provides another method for producing the above-mentioned anisotropic conductive film, comprising the following steps (a) to (d):

(a) a step of arranging metal particles in the concave portions of a transfer mold having regularly arranged concave portions;

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

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

Furthermore, the present invention provides a connection structure in which the aforementioned anisotropic conductive film is disposed between a terminal of a first electronic component and a terminal of a second electronic component, and the first electronic component and the second electronic component are anisotropically conductively connected by heating and pressing.

Effects of the Invention

The anisotropic conductive film of the present invention, which includes metal particles within an insulating film, has the metal particles regularly arranged in a plan view, thereby suppressing the occurrence of short circuits when used for anisotropic conductive connections. Furthermore, the flux is arranged so that it is in contact with or close to at least one of the ends of the metal particles on the anisotropic conductive film's front surface or the back surface. This allows the oxide film on the metal particle surfaces to be removed during anisotropic conductive connections, achieving high conduction reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

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

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

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

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

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

[Fig. 2C] Fig. 2C is a cross-sectional view of the anisotropic conductive film of the present invention.

[ Fig. 3] Fig. 3 is a cross-sectional view of the anisotropic conductive film of the present invention.

[ Fig. 4] Fig. 4 is a cross-sectional view of the anisotropic conductive film of the present invention.

[ Fig. 5] Fig. 5 is a cross-sectional view of the anisotropic conductive film of the present invention.

[ Fig. 6] Fig. 6 is a cross-sectional view of the anisotropic conductive film of the present invention.

[Fig. 7A] Fig. 7A is a process diagram for explaining a method for producing an anisotropic conductive film according to the present invention.

[Fig. 7B] Fig. 7B is a process diagram for explaining the method for producing the anisotropic conductive film of the present invention.

[Fig. 7C] Fig. 7C is a process diagram illustrating a method for producing an anisotropic conductive film according to the present invention.

[FIG. 8A] FIG. 8A is a process diagram for explaining a method for producing an anisotropic conductive film according to the present invention.

[Fig. 8B] Fig. 8B is a process diagram for explaining the method for producing the anisotropic conductive film of the present invention.

[Fig. 8C] Fig. 8C is a process diagram for explaining the method for producing the anisotropic conductive film of the present invention.

[Fig. 8D] Fig. 8D is a process diagram illustrating a method for manufacturing an anisotropic conductive film according to the present invention.

[Fig. 9A] Fig. 9A is a process diagram for explaining a method for producing an anisotropic conductive film according to the present invention.

[Fig. 9B] Fig. 9B is a process diagram for explaining the method for producing the anisotropic conductive film of the present invention.

[Fig. 9C] Fig. 9C is a process diagram illustrating a method for producing an anisotropic conductive film according to the present invention.

[Fig. 9D] Fig. 9D is a process diagram illustrating a method for manufacturing an anisotropic conductive film according to the present invention.

[Fig. 10A] Fig. 10A is a cross-sectional view of an anisotropic conductive film of the present invention.

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

[Fig. 10C] Fig. 10C is a cross-sectional view of the anisotropic conductive film of the present invention.

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

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

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

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

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

[Fig. 12A] Fig. 12A is a process diagram illustrating a method for producing an anisotropic conductive film according to the present invention.

[Fig. 12B] Fig. 12B is a process diagram illustrating a method for producing an anisotropic conductive film according to the present invention.

[Fig. 12C] Fig. 12C is a process diagram illustrating a method for producing an anisotropic conductive film according to the present invention.

[Fig. 12D] Fig. 12D is a process diagram illustrating a method for manufacturing an anisotropic conductive film according to the present invention.

DETAILED DESCRIPTION

Hereinafter, specific examples of the present invention will be described with reference to the accompanying drawings.

As shown in Figures 1A, 1B, and 1C, an anisotropic conductive film 10 of the present invention comprises metal particles 2 within an insulating film 1. Although not shown, the metal particles are regularly arranged in a plan view. The term "regular arrangement" is not particularly limited as long as the arrangement is regular, but preferred examples include rhombic lattice arrangements, hexagonal lattice arrangements, square lattice arrangements, rectangular lattice arrangements, and parallelogram arrangements. Of these, a hexagonal lattice arrangement, which allows for closest packing, is preferred.

The insulating film 1 can be appropriately selected from among those used in conventional anisotropic conductive films. Examples include thermoplastic acrylic or epoxy resin films, and thermosetting or photocuring acrylic or epoxy resin films. Such insulating films typically have a thickness of 10 to 40 μm. Furthermore, the insulating film 1 only needs to be a film, at least in the form of an anisotropic conductive film, but may also be a high-viscosity liquid during its manufacture.

Furthermore, as needed, an insulating filler such as silica particles, alumina, or aluminum hydroxide may be added to the insulating film 1. The insulating filler preferably has an average particle size of 0.01 to 8 μm. The amount of insulating filler blended is preferably 3 to 40 parts by mass per 100 parts by mass of the resin forming the insulating film. This facilitates ensuring conduction reliability after anisotropic conductive connection.

The metal particles 2 are used as metal particles for anisotropic conductive connection in the anisotropic conductive film and can be appropriately selected from particles having an oxide film formed on their surfaces. Preferred examples include solder particles having an average particle size of 10 to 40 μm as measured by an image-type particle size distribution analyzer.

In the anisotropic conductive film of the present invention, the flux 3 is arranged so as to be in contact with or close to at least one of the ends of the metal particles on the surface side of the anisotropic conductive film or the ends on the back side of the anisotropic conductive film. For example, in the embodiment shown in FIG1A , the flux 3 is arranged so as to be in contact with the end 2a on the surface side of the anisotropic conductive film of the metal particle 2. In the embodiment shown in FIG1B , the flux 3 is arranged so as to be in contact with the end 2b on the back side of the anisotropic conductive film of the metal particle 2. In the embodiment shown in FIG1C , the flux 3 is arranged so as to be in contact with each of the end 2a on the surface side of the anisotropic conductive film and the end 2b on the back side of the anisotropic conductive film of the metal particle 2. In these arrangements, when the metal particle 2 and the flux 3 are in contact, the heat generated during the anisotropic conductive connection is used to remove the oxide film on the surface of the metal particle 2 by the flux 3, thereby forming a metallic bond between the metal particle 2 and the terminal to be connected.

The degree of proximity between the metal particles 2 and the solder 3 means that the shortest distance between them is less than 2 μm. If the distance exceeds this, there is a concern that the contact between the two may be hindered during anisotropic conductive connection.

One method for placing the metal particles 2 and flux 3 in close proximity is, for example, mixing the flux with an insulating filler. This is because the insulating filler functions as a spacer, isolating the metal particles 2 from the flux 3. Examples of such insulating fillers include fumed silica with an average primary particle size of 1 to 1000 nm.

Furthermore, the relationship between the amount of metal particles 2 and the flux 3 in contact with or in proximity to them is such that the thickness of the flux 3 is 0.001 to 0.4 times the average particle size of the metal particles 2. Within this range, the surface of the metal particles 2 can be cleaned and corrosion of the anisotropic conductive connection will not occur.

When the flux 3 is arranged in contact with or close to the metal particles 2, the flux is diluted in a solvent (preferably at a dilution ratio of 0.1 to 40 wt % relative to the solvent) and then applied to the transfer mold or the insulating film to which the metal particles are attached using a known coating method, as described below, and then dried as needed.

Furthermore, the flux 3 removes the oxide film on the surface of the metal particles 2 under the heating conditions during anisotropic conductive connection. As such flux 3, a known flux corresponding to the material of the metal particles 2 can be used.

In addition, in the embodiments of Figures 1A to 1C, the metal particles 2 are isolated from the surface or back surface of the insulating film 1, but they can also be exposed on the surface or back surface of the insulating film 1. For example, the embodiment of Figure 1A can be modified so that the end of the metal particle 2 opposite to the end 2a is exposed on the back surface of the insulating film 1, as shown in Figure 2A. In this case, the flux 3 is arranged so that it contacts the end 2a. The embodiment of Figure 1B can also be modified so that the flux 3 arranged in contact with the end 2b is exposed, as shown in Figure 2B. The embodiment of Figure 1C can also be modified as shown in Figure 2C.

In Figures 1A to 1C and 2A to 2C, the insulating film 1 is a single layer. However, as shown in Figure 3 , the insulating film 1 may have a two-layer structure (1a and 1b), with metal particles 2 disposed between the layers. This two-layer structure increases manufacturing flexibility.

Furthermore, as shown in FIG4 , the anisotropic conductive film 10 of the present invention also includes a configuration in which a portion of the surface of the metal particles 2 is not in contact with the flux 3. In FIG4 , the surface portion of the metal particles 2 not in contact with the flux 3 faces the side of the film, but may face either the front or back side of the film. In particular, as shown in FIG5 , it is preferred that the surface portion of the metal particles 2 not in contact with the flux 3 be positioned opposite the surface portion of the metal particles in contact with the flux.

Alternatively, as shown in FIG6 , flux 3 may be disposed between adjacent metal particles 2 in the plane direction of the anisotropic conductive film 10 of the present invention. With such anisotropic conductive film 10, during anisotropic conductive connection, the flux 3 disposed between adjacent metal particles 2 is drawn closer by the metal particles 2, thereby enabling a sufficient amount of flux to clean the metal particle surfaces and preventing delamination of the two-layer insulating film. In this case, the amount of flux per unit area disposed at at least one of the anisotropic conductive film surface-side end 2a or the anisotropic conductive film back-side end 2b of the metal particle 2 is preferably greater than the amount of flux per unit area disposed between adjacent metal particles 2.

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

(Process (A))

First, as shown in Figures 7A to 7C , flux 3 is placed at least at the bottom of each recess 50 of a transfer mold 100 having regularly arranged recesses 50. Specifically, flux 3 may be placed only at the bottom of each recess 50, as shown in Figure 7A , or may be placed on the entire inner wall surface, including the bottom of each recess 50, as shown in Figure 7B . Alternatively, flux 3 may be placed on the surface between the bottom of each recess 50 and an adjacent recess 50 of the transfer member 100, as shown in Figure 7C . In the case of Figure 7C , the amount of flux per unit area at the bottom of each recess 50 is preferably greater than the amount of flux per unit area on the surface between adjacent recesses 50.

The transfer mold 100 can be made using a known method. For example, a master mold can be made by machining a metal plate, applying a curable resin composition to the master mold, and curing the composition. Specifically, a flat metal plate is cut to form a transfer mold master mold with convex portions corresponding to the concave portions. The curable resin composition constituting the transfer mold is applied to the surface of the master mold that forms the convex portions, cured, and then pulled away from the master mold to obtain the transfer mold.

The flux 3 can be arranged at least on the bottom of the recess 50 by a known method. For example, the flux can be applied to the entire surface of the transfer mold by screen printing and then scraped off the outermost flux with a scraper as needed.

(Process (B))

Next, as shown in Figures 8A to 8C , metal particles 2 are placed in the recesses 50 where the flux 3 is placed. Known methods can be used to place the metal particles 2. For example, the metal particles can be dispersed onto the surface of the transfer mold, and any metal particles on the transfer mold surface outside the recesses can be removed using an air blower or a cutter. Alternatively, a microdispenser can be used to supply the metal particles one by one into the recesses.

Alternatively, after the metal particles are supplied to the concave portion of the transfer mold as shown in FIG8A , the flux 3 may be disposed on the surface of the metal particles 2 by a process method as shown in FIG8D .

(Process (C))

Next, as shown in Figures 9A to 9D , the insulating film 1 is brought into contact with the concave portion 50 side of the transfer mold 100 ( Figures 8A to 8D ) with the metal particles 2 arranged thereon, and heat and pressure are applied to transfer the metal particles 2 onto the insulating film 1. In this state, if the insulating film 1 is tightly wound around a roll, an anisotropic conductive film 10 shown in Figure 10A can be obtained using the method shown in Figure 9A , an anisotropic conductive film 10 shown in Figure 10B can be obtained using the method shown in Figure 9B , an anisotropic conductive film 10 shown in Figure 10C can be obtained using the method shown in Figure 9C , and an anisotropic conductive film 10 shown in Figure 10D can be obtained using the method shown in Figure 9D .

In addition, in order to make the insulating film have a two-layer structure, the manufacturing method of the present invention preferably further includes the following step (D).

(Process (D))

That is, by hot-pressing another insulating film onto the metal particle transfer surface of the insulating film (FIGS. 9A to 9D) onto which the metal particles are transferred, an anisotropic conductive film 10 of FIG. 11A having a two-layer structure of the insulating film 1 (1a and 1b) can be obtained by the method of FIG. 9A , an anisotropic conductive film 10 of FIG. 11B having a two-layer structure of the insulating film 1 (1a and 1b) can be obtained by the method of FIG. 9B , an anisotropic conductive film 10 of FIG. 11C having a two-layer structure of the insulating film 1 (1a and 1b) can be obtained by the method of FIG. 9C , and an anisotropic conductive film 10 of FIG. 11D having a two-layer structure of the insulating film 1 (1a and 1b) can be obtained by the method of FIG. 9D .

Furthermore, 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 , metal particles 2 are placed in recesses 50 of a transfer mold 200 having recesses 50 arranged regularly.

(Process (b))

Next, as shown in FIG. 12B , flux 3 is placed on the concave portion-forming surface of transfer mold 200 where metal particles 2 are placed.

(Process (c))

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

(Process (d))

Next, as shown in FIG12D , another insulating film 1b is thermally pressed onto the metal particle transfer surface of the insulating film 1a to which the metal particles 2 have been transferred. This yields an anisotropic conductive film 10 having a two-layer structure with flux 3 disposed between the insulating film 1a and the other insulating film 1b.

＜Connection structure＞

The anisotropic conductive film of the present invention is useful for producing a connection structure in which the first and second electronic components are anisotropically conductively connected by heating and pressurizing, by being disposed between terminals of a first electronic component such as an IC chip or a semiconductor wafer and terminals of a second electronic component such as a wiring substrate or a semiconductor wafer. Such a connection structure is also one embodiment of the present invention.

Example

Hereinafter, the present invention will be described in detail with reference to examples.

Example 1

A 2mm thick nickel plate was prepared, and cylindrical projections (25μm outer diameter, 20μm height) were formed in a square lattice pattern as a transfer master. The center-to-center distance between adjacent projections was 40μm, resulting in a projection density of 625/ ^mm2 .

A photopolymerizable resin composition containing 60 parts by mass of a phenoxy resin (YP-50, Nippon Steel & Sumikin Chemical Co., Ltd.), 29 parts by mass of an acrylic resin (M208, Toagosei Co., Ltd.), and 2 parts by mass of a photopolymerization initiator (IRGACURE 184, BASF Japan Co., Ltd.) was applied to the resulting transfer master so as to have a dry thickness of 30 μm. After drying at 80°C for 5 minutes, the composition was irradiated with 1000 mJ of light using a high-pressure mercury lamp to produce a transfer body.

A flux (ESR-250T4, Senju Metal Industry Co., Ltd.) diluted with toluene to 5 wt% was applied to the transfer mold peeled from the transfer mold master using a squeegee. The flux thickness in the concave portion after drying was 1 μm, and the flux on the surface of the transfer mold was scraped off.

In this transfer mold, solder particles having an average particle size of 20 μm (fine solder powder, Mitsui Mining & Smelting Co., Ltd.) were dispersed, and then the concave portions were filled with the solder particles by air blowing.

A 20-μm-thick insulating film (composed of 60 parts by mass of a phenoxy resin (YP-50, Nippon Steel & Sumikin Chemical Co., Ltd.), 40 parts by mass of an epoxy resin (jER828, Mitsubishi Chemical Corporation), and 2 parts by mass of a cationic curing agent (SI-60L, Sanshin Chemical Industry Co., Ltd.)) was placed on the solder particle-attached surface of the transfer mold to which the conductive particles were attached. Pressing was performed at a temperature of 50°C and a pressure of 0.5 MPa to transfer the solder particles onto the insulating film.

On the solder particle-transferred surface of the resulting insulating film, another insulating film having a thickness of 5 μm (a film composed of 60 parts by mass of a phenoxy resin (YP-50, Nippon Steel & Sumikin Chemical Co., Ltd.), 40 parts by mass of an epoxy resin (jER828, Mitsubishi Chemical Co., Ltd.), and 2 parts by mass of a cationic curing agent (SI-60L, Sanshin Chemical Industry Co., Ltd.)) was stacked at a temperature of 60°C and a pressure of 2 MPa to obtain an anisotropic conductive film.

Example 2

The same transfer mold as in Example 1 was prepared. Solder particles with an average particle size of 20 μm (fine solder powder, Mitsui Mining & Smelting Co., Ltd.) were dispersed in the transfer mold, and then the concave portions were filled with the solder particles by air blowing.

A flux (ESR-250T4, Senju Metal Industry Co., Ltd.) diluted with toluene to 20 wt % was applied to the surface of the transfer mold filled with solder particles using a squeegee so that the flux thickness after drying became 1 μm.

A 20-μm-thick insulating film (composed of 60 parts by mass of a phenoxy resin (YP-50, Nippon Steel & Sumikin Chemical Co., Ltd.), 40 parts by mass of an epoxy resin (jER828, Mitsubishi Chemical Corporation), and 2 parts by mass of a cationic curing agent (SI-60L, Sanshin Chemical Industry Co., Ltd.)) was placed on the solder surface and pressed at a temperature of 50°C and a pressure of 0.5 MPa to transfer solder particles to the insulating film.

On the solder particle-transferred surface of the resulting insulating film, another insulating film having a thickness of 5 μm (a film composed of 60 parts by mass of a phenoxy resin (YP-50, Nippon Steel & Sumikin Chemical Co., Ltd.), 40 parts by mass of an epoxy resin (jER828, Mitsubishi Chemical Co., Ltd.), and 2 parts by mass of a cationic curing agent (SI-60L, Sanshin Chemical Co., Ltd.)) was superimposed and laminated at a temperature of 60°C and a pressure of 2 MPa to obtain an anisotropic conductive film.

Comparative Example 1

Except for not using the flux, Example 1 was repeated to obtain an anisotropic conductive film.

Example 3

A transfer mold similar to that used in Example 1 was prepared. Similarly to Example 1, flux was placed at the bottom of the concave portion of the transfer mold, and then the concave portion was filled with solder particles. The surface of the transfer mold was again coated with flux (ESR-250T4, Senju Metal Industry Co., Ltd.) diluted to 5 wt% with toluene using a squeegee. The same procedures as in Example 1 were then repeated to produce an anisotropic conductive film. The coating thickness of the flux after drying was 1 μm at the edge of the solder particle film interface and less than 1 μm between solder particles.

Example 4

An anisotropic conductive film was obtained by repeating Example 1 except that the dilution of the flux (ESR-250T4, Senju Metal Industry Co., Ltd.) with toluene was changed from 5 wt % to 10 wt % and the coating thickness after drying was set to 2 μm.

(evaluate)

The resulting anisotropic conductive film was used to anisotropically conductively connect a test IC chip with gold bumps measuring 100μm x 100μm x 15μm (height) to a glass epoxy substrate (material: FR4) for IC mounting under the conditions of 180°C, 40mPa, and heat-pressing for 20 seconds, resulting in a connection structure. The connection structure was measured for initial on-resistance, on-resistance after a high-pressure cook test (PCT) (test conditions: 121°C, 2atm pressure, 200 hours), and on-resistance after a high-temperature, high-humidity bias test (test conditions: 50V applied, 85°C, 85% humidity). The results are shown in Table 1.

Furthermore, for practical purposes, the initial on-resistance value needs to be less than 1Ω, and the on-resistance value after PCT and after high-temperature and high-humidity bias testing needs to be less than 15Ω.

[Table 1]

On-resistance (Ω)	Comparative Example 1	Example 1	Example 2	Example 3	Example 4
						initial	0.1	0.1	0.1	0.1	0.1
Post-PCT	120	5	5	5	5
						After high temperature and high humidity bias test	80	5	10	10	7

As shown in Table 1, the anisotropic conductive films of Examples 1 to 4 achieved good results in all evaluation parameters because the solder particles and flux were arranged in contact within the film. In contrast, in Comparative Example 1, the solder particles and flux were not arranged in contact within the film, resulting in a significant increase in on-resistance after the PCT test and the high-temperature, high-humidity bias test.

Example 5

An anisotropic conductive film was obtained by repeating the procedure of Example 1, except that a film composed of 60 parts by mass of a phenoxy resin (YP-50, Nippon Steel & Sumikin Chemical Co., Ltd.), 40 parts by mass of an epoxy resin (jER828, Mitsubishi Chemical Corporation), 10 parts by mass of a fumed silica (R200, Nippon Aerosil Co., Ltd.), and 2 parts by mass of a cationic curing agent (SI-60L, Sanshin Chemical Industry Co., Ltd.) was used as a 20 μm thick insulating film to which solder particles were transferred. The resulting anisotropic conductive film, like the anisotropic conductive film of Example 1, exhibited good results in all evaluation criteria.

Industrial applicability

The anisotropic conductive film of the present invention suppresses the occurrence of short circuits in the connection structure obtained by using it for anisotropic conductive connection, and can not only suppress the initial on-resistance value, but also suppress the on-resistance value after PCT and high-temperature and high-humidity bias test to a lower level. Therefore, it is useful when installing an IC chip on a wiring substrate.

Label Description

1, 1a, 1b: insulating film; 2: metal particles; 2a, 2b: the front or back side end of the anisotropic conductive film of the metal particles; 3: solder; 10: anisotropic conductive film; 50: concave portion of the transfer mold; 100, 200: transfer mold.

Technical Field

Background Art

Prior Art Literature

Patent Literature

Patent Document 1: Japanese Patent Application Laid-Open No. 2014-60150.

Summary of the Invention

Problems to be solved by the invention

Solutions to Problems

Effects of the Invention

BRIEF DESCRIPTION OF THE DRAWINGS

DETAILED DESCRIPTION

(Process (A))

(Process (B))

(Process (C))

(Process (D))

(Process (a))

(Process (b))

(Process (c))

(Process (d))

＜Connection structure＞

Example

Example 1

Example 2

Comparative Example 1

Example 3

Example 4

(evaluate)

[Table 1]

Example 5

Industrial applicability

Label Description

Technical Field

Background Art

Prior Art Literature

Patent Literature

Patent Document 1: Japanese Patent Application Laid-Open No. 2014-60150.

Summary of the Invention

Problems to be solved by the invention

Solutions to Problems

Effects of the Invention

BRIEF DESCRIPTION OF THE DRAWINGS

DETAILED DESCRIPTION

(Process (A))

(Process (B))

(Process (C))

(Process (D))

(Process (a))

(Process (b))

(Process (c))

(Process (d))

＜Connection structure＞

Example

Example 1

Example 2

Comparative Example 1

Example 3

Example 4

(evaluate)

[Table 1]

Example 5

Industrial applicability

Label Description

Claims

1. An anisotropic conductive film comprising metal particles within an insulating film, wherein the metal particles are regularly arranged when viewed from above, and are configured such that flux contacts or approaches at least one end of the metal particles on the surface side or the back side of the anisotropic conductive film.

In this process, a portion of the surface of the metal particles does not come into contact with the flux.

2. The anisotropic conductive film as described in claim 1, wherein the metal particles are solder particles.

3. The anisotropic conductive film as described in claim 1 or 2, wherein the insulating film has a two-layer structure with metal particles disposed between the layers.

4. The anisotropic conductive film as claimed in claim 1 or 2, wherein the surface portion of the metal particle that is not in contact with the flux is disposed on the opposite side of the surface portion of the metal particle that is in contact with the flux.

5. The anisotropic conductive film as claimed in claim 1 or 2, wherein, in the planar direction of the anisotropic conductive film, flux is disposed between adjacent metal particles.

6. The anisotropic conductive film as claimed in claim 5, wherein the flux disposed between adjacent metal particles is disposed between the layers of the two-layer insulating film.

7. The anisotropic conductive film as claimed in claim 5, wherein the solder amount per unit area at at least one end of the anisotropic conductive film disposed on the surface side end or the back side end of the anisotropic conductive film disposed on the metal particles is greater than the solder amount per unit area disposed between adjacent metal particles.

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

(A) A process of placing flux in at least the bottom of the recesses of a transfer mold having regularly arranged recesses;

(B) The process of depositing metal particles in a recess containing flux; and

(C) A process of transferring metal particles onto an insulating film by bringing the insulating film against the recessed side of a transfer mold containing metal particles and heating and pressing it.

9. The manufacturing method as described in claim 8, further comprising step (D):

(D) The process of hot-pressing other insulating films onto the metal particle transfer surface of an insulating film with metal particles transferred on.

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

(a) A process of placing metal particles in the recesses of a transfer mold having regularly arranged recesses;

(b) The process of applying flux to the recessed surface of the transfer mold where metal particles are disposed;

(c) The process of transferring metal particles onto an insulating film by pressing and heating it against the flux-filled side of the transfer mold; and

11. A connection structure comprising an anisotropic conductive film as described in claims 1 to 7 disposed between a terminal of a first electronic component and a terminal of a second electronic component, wherein the first electronic component and the second electronic component are anisotropically conductively connected by heating and pressurization.