JP2022186787A - Anisotropic conductive film, manufacturing method thereof, connecting structure, and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an anisotropic conductive film useful for manufacturing a connection structure having both excellent insulation reliability and conduction reliability even when a connecting portion of circuit members to be electrically connected to each other is minute.

SOLUTION: A manufacturing method of an anisotropic conductive film according to the present invention includes, in this order, (a) a step of accommodating one or a plurality of solder particles respectively in a plurality of openings provided in the transfer mold, (b) a step of obtaining a first film to which the solder particles are transferred by bringing an insulating adhesive component into contact with the side where the transfer mold opening is provided, and (c) a step of obtaining an anisotropic conductive film by forming a second film including the insulating adhesive component on the surface of the first film on the side to which the solder particles are transferred.

SELECTED DRAWING: Figure 7

COPYRIGHT: (C)2023,JPO&INPIT

Description

TECHNICAL FIELD The present invention relates to an anisotropic conductive film and its manufacturing method, and a connection structure and its manufacturing method.

Methods for mounting a liquid crystal driving IC on a liquid crystal display glass panel can be roughly classified into COG (Chip-on-Glass) mounting and COF (Chip-on-Flex) mounting. In COG mounting, an anisotropic conductive adhesive containing conductive particles is used to bond the liquid crystal driving IC directly onto the glass panel. On the other hand, in COF mounting, a liquid crystal driving IC is bonded to a flexible tape having metal wiring, and these are bonded to a glass panel using an anisotropic conductive adhesive containing conductive particles. The term "anisotropic" as used herein means that it conducts in the pressurized direction and maintains insulation in the non-pressurized direction.

By the way, with the recent increase in definition of liquid crystal displays, the pitch and area of metal bumps, which are circuit electrodes of liquid crystal driving ICs, are becoming narrower. There is a risk that it will flow out between the electrodes and cause a short circuit. This tendency is particularly noticeable in COG mounting. If the conductive particles flow out between the adjacent circuit electrodes, the number of conductive particles trapped between the metal bumps and the glass panel decreases, and there is a risk of connection failure in which the connection resistance between the facing circuit electrodes increases. Such a tendency is more pronounced when less than 20,000 particles/mm ² of conductive particles are added per unit area.

As a method for solving these problems, a method has been proposed in which a plurality of insulating particles (child particles) are attached to the surface of a conductive particle (mother particle) to form a composite particle. For example, Patent Documents 1 and 2 propose a method of adhering spherical resin particles to the surfaces of conductive particles. Furthermore, even when 70,000/mm ² or more conductive particles are added per unit area, insulation-coated conductive particles with excellent insulation reliability have been proposed. proposed insulating coated conductive particles in which second insulating particles having a glass transition temperature lower than that of the first insulating particles are attached to the surfaces of the conductive particles. In addition, Patent Document 4 proposes a conductive paste containing solder particles from the viewpoint of strengthening the connection between electrodes.

Japanese Patent No. 4773685 Japanese Patent No. 3869785 JP 2014-17213 A JP 2016-76494 A

By the way, when the connection points of the circuit members to be electrically connected to each other are minute (for example, the bump area is less than 2000 μm ² ), it is preferable to increase the number of conductive particles in order to obtain stable conduction reliability. For these reasons, there are cases where 100,000 particles/mm ² or more of conductive particles per unit area are introduced. However, when the connection point is minute like this, even if the insulation-coated conductive particles described in Patent Documents 1 to 3 are used, it is difficult to balance conduction reliability and insulation reliability, and there is still room for improvement. was there. On the other hand, when the conductive paste containing the solder particles described in Patent Document 4 is used, sufficient reliability of conduction can be ensured, but the reliability of insulation is insufficient.

The present invention has been made in view of the above problems, and manufactures a connection structure that is excellent in both insulation reliability and conduction reliability even if the connection points of circuit members to be electrically connected to each other are minute. An object of the present invention is to provide an anisotropic conductive film and a method for producing the same that are useful for Another object of the present invention is to provide a connection structure manufactured using this anisotropic conductive film and a manufacturing method thereof.

In order to solve the above problems, the present inventors investigated the reason why the insulation resistance value is lowered by the conventional method. As a result, in the inventions described in Patent Documents 1 and 2, the coverage of the insulating particles coated on the surface of the conductive particles is low, and the amount of conductive particles charged is about 20,000/mm ² or less per unit area. However, it was found that the insulation resistance value easily decreased.

In the invention described in Patent Document 3, in order to compensate for the drawbacks of the inventions described in Patent Documents 1 and 2, first insulating particles and second insulating particles having a lower glass transition temperature than the first insulating particles are used. It is attached to the surface of the conductive particles. As a result, a sufficiently high insulation resistance value can be maintained when the amount of conductive particles charged is about 70,000 particles/mm ² per unit area. However, it was found that there is a possibility that the insulation resistance value becomes insufficient when the amount of conductive particles charged is 100,000/mm ² or more per unit area.

In the invention described in Patent Document 4, by using a conductive paste containing solder particles, it is recognized that excellent conduction reliability can be achieved compared to the inventions described in Patent Documents 1 to 3. If the connection points of the circuit members to be electrically connected to each other are minute (for example, the bump area is less than 2000 μm ² ), solder particles tend to remain in areas other than the connection between the bumps, resulting in insufficient insulation reliability. It was found that there is a possibility that

The present invention has been made based on the above findings of the present inventors. The present invention provides a method for producing an anisotropic conductive film comprising the following steps in this order.
(a) A step of accommodating one or a plurality of solder particles in a plurality of openings provided in a transfer mold.
(b) A step of obtaining a first film to which solder particles have been transferred by bringing an adhesive component having insulating properties into contact with the side of the transfer mold provided with the openings.
(c) A step of obtaining an anisotropic conductive film by forming a second film made of an insulating adhesive component on the surface of the first film to which the solder particles have been transferred.

According to the above method for producing an anisotropic conductive film, by using a transfer mold, a particle group consisting of one solder particle or a plurality of solder particles is formed in a predetermined region in the thickness direction of the anisotropic conductive film. An anisotropic conductive film can be manufactured in which adjacent solder particles or particle groups are arranged in parallel with a space therebetween. For example, by manufacturing an anisotropic conductive film using a transfer mold suitable for the pattern of electrodes to be connected, the position and number of solder particles in the anisotropic conductive film can be sufficiently controlled. By manufacturing a connection structure using such an anisotropic conductive film, while ensuring a sufficient number of solder particles present between a pair of electrodes to be electrically connected to each other, insulation should be maintained. The number of solder particles present between adjacent electrodes can be sufficiently reduced. This makes it possible to sufficiently efficiently and stably manufacture a connection structure that is excellent in both insulation reliability and conduction reliability even if the circuit members are connected at minute locations.

Solder particles may be exposed on the surface of the first film obtained in the step (b), or solder particles may be embedded on the surface side of the first film. In order to embed the solder particles on the surface side of the first film, the adhesive component should be allowed to penetrate into the inside of the openings in the step (b). In addition, in order to fix the transferred solder particles in the first film obtained in the step (b), the step (b) may have a step of curing the adhesive component after the solder particles are transferred. good.

In the present invention, the average particle size of solder particles is preferably 0.6 to 15 μm. The solder particles preferably comprise tin or tin alloys. Specific examples of tin alloys constituting solder particles include In--Sn alloys, In--Sn--Ag alloys, Sn--Bi alloys, Sn--Bi--Ag alloys, Sn--Ag--Cu alloys and Sn--Cu alloys. . From the viewpoint of achieving high conduction reliability, the surfaces of the solder particles are preferably coated with a flux component.

The present invention provides an anisotropic conductive film having the following structure. That is, an anisotropic conductive film according to the present invention includes an insulating film made of an adhesive component having insulating properties and a plurality of solder particles arranged in the insulating film, and the anisotropic conductive film In the longitudinal section of , one solder particle or a particle group consisting of a plurality of solder particles are arranged in a horizontal direction while being separated from an adjacent solder particle or particle group. Here, the term "longitudinal section" means a section perpendicular to the main surface of the anisotropic conductive film, and the term "transverse direction" means a direction parallel to the main surface of the anisotropic conductive film. .

From the viewpoint of achieving both more excellent insulation reliability and conduction reliability of the connection structure, it is preferable that the particle groups are regularly arranged in the cross section of the anisotropic conductive film.

The present invention provides a method of manufacturing a connected structure using the anisotropic conductive film. That is, a method for manufacturing a connected structure according to the present invention comprises preparing a first circuit member having a first substrate and a first electrode provided on the first substrate; providing a second circuit member having a second electrode electrically connected; a side of the first circuit member having the first electrode and a side of the second circuit member having the second electrode Placing the anisotropic conductive film between; Pressing the laminate containing the first circuit member, the anisotropic conductive film, and the second circuit member in the thickness direction of the laminate and electrically connecting the first electrode and the second electrode through the solder and bonding the first circuit member and the second circuit member by heating the solder particles above the melting point.

According to the method for manufacturing the connection structure, even if the connecting portion between the first electrode and the second electrode is minute, the connection structure excellent in both insulation reliability and conduction reliability can be sufficiently efficiently and efficiently manufactured. It can be manufactured stably. That is, by heating the laminate to a temperature equal to or higher than the melting point of the solder particles while pressing the laminate in the thickness direction, the solder particles melt and move between the first electrode and the second electrode. Together, the first electrode and the second electrode are joined via solder. Thereby, it is possible to obtain good conduction reliability between the first electrode and the second electrode. In addition to this, since the solder particles gather while melting between the first electrode and the second electrode, it becomes difficult for the solder particles to remain between the adjacent electrodes, which should maintain insulation. is suppressed, and high insulation reliability can be obtained.

The present invention provides a connection structure having the following configuration. That is, the connection structure according to the present invention includes a first circuit member having a first substrate and a first electrode provided on the first substrate, and electrically connected to the first electrode. a second circuit member having a second electrode thereon; a solder joint interposed between the first electrode and the second electrode; and a solder joint provided between the first circuit member and the second circuit member. a first circuit member and an insulating adhesive layer adhering to the second circuit member.

In the present invention, at least one of the first electrode and the second electrode is preferably made of a material selected from the group consisting of copper, nickel, palladium, gold, silver and alloys thereof, and indium tin oxide. . When at least one of the first electrode and the second electrode is made of copper, the first electrode and the second electrode may be connected via a layer made of an intermetallic compound. The thickness of the intermetallic compound layer is preferably 0.1 to 10.0 μm from the viewpoint of conduction reliability and connection strength. The term "layer made of an intermetallic compound" refers to a layer formed by diffusion of copper into a solder layer when solder particles are melted to form a solder layer.

INDUSTRIAL APPLICABILITY According to the present invention, an anisotropic conductive material useful for manufacturing a connection structure excellent in both insulation reliability and conduction reliability even if the connection points of circuit members to be electrically connected to each other are minute. A film and method of making the same are provided. Moreover, according to this invention, the connection structure manufactured using this anisotropic conductive film, and its manufacturing method are provided.

FIG. 1 is a longitudinal sectional view schematically showing a first embodiment of an anisotropic conductive film according to the invention. FIG. 2(a) is a schematic cross-sectional view taken along line IIa--IIa shown in FIG. 1, and FIG. 2(b) is a cross-sectional view schematically showing a modification of the first embodiment. FIG. 3 is a longitudinal sectional view schematically showing a second embodiment of the anisotropic conductive film according to the invention. FIG. 4(a) is a schematic cross-sectional view taken along line IVa-IVa in FIG. 3, and FIG. 4(b) is a cross-sectional view schematically showing a modification of the second embodiment. FIG. 5(a) is a plan view schematically showing an example of a transfer mold, and FIG. 5(b) is a sectional view taken along line bb shown in FIG. 5(a). FIG. 6 is a cross-sectional view schematically showing a state in which one solder particle is trapped in each concave portion of the transfer mold. 7A to 7C are cross-sectional views schematically showing an example of the manufacturing process of the anisotropic conductive film according to the first embodiment. 8(a) and 8(b) are a cross-sectional view and a plan view schematically showing a state in which a plurality of solder particles are accommodated in respective recesses of the transfer mold. 9A to 9C are cross-sectional views schematically showing an example of the manufacturing process of the anisotropic conductive film according to the second embodiment. FIG. 10 is an enlarged view showing a part of the connection structure according to the present invention, schematically showing a first example of a state in which the first electrode and the second electrode are electrically connected by solder. 3 is a cross-sectional view shown in FIG. FIG. 11 is an enlarged view showing a part of the connection structure according to the present invention, schematically showing a second example of a state in which the first electrode and the second electrode are electrically connected by solder. 3 is a cross-sectional view shown in FIG. FIG. 12 is an enlarged view showing a part of the connection structure according to the present invention, schematically showing a third example of a state in which the first electrode and the second electrode are electrically connected by solder. 3 is a cross-sectional view shown in FIG. FIG. 13 is an enlarged view showing a part of the connection structure according to the present invention, schematically showing a fourth example in which the first electrode and the second electrode are electrically connected by solder. 3 is a cross-sectional view shown in FIG. FIG. 14 is an enlarged view showing a part of the connection structure according to the present invention, schematically showing a fifth example in which the first electrode and the second electrode are electrically connected by solder. 3 is a cross-sectional view shown in FIG. FIG. 15 is an enlarged view showing a part of the connection structure according to the present invention, schematically showing a sixth example in which the first electrode and the second electrode are electrically connected by solder. 3 is a cross-sectional view shown in FIG. 16(a) and 16(b) are cross-sectional views schematically showing a first example of the manufacturing process of the connection structure according to the present invention. 17(a) and 17(b) are cross-sectional views schematically showing a second example of the manufacturing process of the connection structure according to the present invention. 18(a) and 18(b) are cross-sectional views schematically showing a third example of the manufacturing process of the connection structure according to the present invention. 19(a) and 19(b) are cross-sectional views schematically showing a fourth example of the manufacturing process of the connection structure according to the present invention. 20(a) and 20(b) are cross-sectional views schematically showing a fifth example of the manufacturing process of the connection structure according to the present invention. 21(a) and 21(b) are cross-sectional views schematically showing a sixth example of the manufacturing process of the connection structure according to the present invention. FIG. 22 is a plan view schematically showing a first example of the relationship between the positions of solder particles on an anisotropic conductive film before being pressed and heated and the positions of bumps (electrodes). FIG. 23 is a plan view schematically showing a second example of the relationship between the positions of solder particles on an anisotropic conductive film before being pressed and heated and the positions of bumps (electrodes). FIG. 24 is a plan view schematically showing a third example of the relationship between the positions of solder particles on an anisotropic conductive film before being pressed and heated and the positions of bumps (electrodes). FIG. 25 is a plan view schematically showing a fourth example of the relationship between the positions of the solder particles on the anisotropic conductive film before being pressed and heated and the bumps (electrodes).

Embodiments of the present invention will be described below. The present invention is not limited to the following embodiments. The materials exemplified below may be used singly or in combination of two or more unless otherwise specified. The content of each component in the composition means the total amount of the plurality of substances present in the composition unless otherwise specified when there are multiple substances corresponding to each component in the composition. A numerical range indicated using "-" indicates a range including the numerical values before and after "-" as the minimum and maximum values, respectively. In the numerical ranges described stepwise in this specification, the upper limit value or lower limit value of the numerical range at one step may be replaced with the upper limit value or lower limit value of the numerical range at another step. In the numerical ranges described herein, the upper or lower limits of the numerical ranges may be replaced with the values shown in the examples.

<Anisotropic conductive film>
The anisotropic conductive film 10 according to the first embodiment shown in FIG. It is configured. In a predetermined longitudinal section of the anisotropic conductive film 10, one solder particle 1 is arranged so as to be aligned in the horizontal direction (horizontal direction in FIG. 1) while being separated from one adjacent solder particle 1. In other words, the anisotropic conductive film 10 has, in its longitudinal section, a central region 10a in which a plurality of solder particles 1 are arranged in rows in the horizontal direction, and surface side regions 10b and 10c in which solder particles 1 are substantially absent. It is composed of

FIG. 2(a) is a schematic cross-sectional view taken along line IIa-IIa shown in FIG. As shown in the figure, the solder particles 1 are regularly arranged in the cross section of the anisotropic conductive film 10 . As shown in FIG. 2(a), the solder particles 1 may be arranged at regular and substantially uniform intervals over the entire area of the anisotropic conductive film 10, as shown in FIG. 2(b). As in the above modified example, in the cross section of the anisotropic conductive film 10, a region 10d in which the plurality of solder particles 1 are regularly arranged and a region 10e in which the solder particles 1 are not substantially present are regular. The solder particles 1 may be arranged such that they are formed in a uniform manner. For example, the position and number of solder particles 1 may be set according to the shape, size, pattern, and the like of the electrodes to be connected.

An anisotropic conductive film 20 according to the second embodiment shown in FIG. It is configured. Particle group 1A consists of a plurality of solder particles 1 . In a predetermined longitudinal section of the anisotropic conductive film 20, one particle group 1A is arranged so as to be aligned in the horizontal direction (horizontal direction in FIG. 3) while being separated from one adjacent particle group 1A. In other words, the anisotropic conductive film 20 has, in its vertical cross section, a central region 20a in which a plurality of particle groups 1A are arranged in rows in the horizontal direction, and surface side regions 20b and 20c in which the particle groups 1A are substantially absent. It is composed of

FIG. 4(a) is a schematic cross-sectional view taken along line IVa-IVa shown in FIG. As shown in the figure, the particle groups 1A are regularly arranged in the cross section of the anisotropic conductive film 20 . As shown in FIG. 4(a), the particle groups 1A may be arranged at regular and substantially uniform intervals over the entire area of the anisotropic conductive film 20, and shown in FIG. 4(b). In the cross section of the anisotropic conductive film 20, a region 20d in which the plurality of particle groups 1A are regularly arranged and a region 20e in which the particle groups 1A are substantially absent are regular. You may arrange|position the particle group 1A so that it may form uniformly. For example, the position, number, etc. of the particle group 1A may be set according to the shape, size, pattern, etc. of the electrode to be connected.

(solder particles)
The particle size of the solder particles 1 is, for example, 0.4-30 μm, and may be 0.5-20 μm or 0.6-15 μm. When the particle diameter of the solder particles 1 is less than 0.4 μm, the solder particles 1 are easily affected by oxidation of the solder surface, and the solder particles 1 are brought to the melting point in a state where the solder particles 1 are pressed by a pair of electrodes to be electrically connected. Even if the solder is heated to the above temperature, the solder particles 1 tend to remain as fine particles without being melted, and the electrical connection reliability tends to be insufficient. On the other hand, when the particle size of the solder particles 1 exceeds 30 μm, the insulation reliability tends to be insufficient.

The average particle size of the solder particles 1 is, for example, 0.6-15 μm, and may be 1.0-12 μm or 1.2-10 μm. When the average particle size of the solder particles 1 is less than 0.6 μm, the solder particles 1 are easily affected by oxidation of the solder surface, and the solder particles 1 are removed while being pressed by a pair of electrodes to be electrically connected. Even if the solder particles 1 are heated above the melting point, the solder particles 1 tend to remain as fine particles without being melted, and the electrical connection reliability tends to be insufficient. On the other hand, when the average particle size of the solder particles 1 exceeds 15 μm, the insulation reliability tends to be insufficient.

The particle size of the solder particles 1 can be measured by observation using a scanning electron microscope (hereinafter referred to as SEM). That is, the average particle diameter of solder particles is obtained by measuring the particle diameters of arbitrary 300 solder particles by observation using an SEM and taking the average value thereof.

Solder particles 1 contain tin or a tin alloy. As the tin alloy, for example, In--Sn, In--Sn--Ag, Sn--Bi, Sn--Bi--Ag, Sn--Ag--Cu and Sn--Cu can be used, and the following examples are given.
・In-Sn (In52% by mass, Bi48% by mass, melting point 118° C.)
・In-Sn-Ag (20% by mass of In, 77.2% by mass of Sn, 2.8% by mass of Ag, melting point 175°C)
・Sn-Bi (Sn 43% by mass, Bi 57% by mass, melting point 138°C)
・Sn-Bi-Ag (42% by mass of Sn, 57% by mass of Bi, 1% by mass of Ag, melting point 139°C)
・Sn-Ag-Cu (Sn 96.5% by mass, Ag 3% by mass, Cu 0.5% by mass, melting point 217°C)
・Sn-Cu (Sn 99.3% by mass, Cu 0.7% by mass, melting point 227°C)

The above tin alloy can be selected according to the connection temperature. For example, when it is desired to connect at a low temperature, an In--Sn alloy or a Sn--Bi alloy may be used, and the connection can be made at 150.degree. C. or lower. When a material with a high melting point such as Sn--Ag--Cu and Sn--Cu is used, it tends to be possible to achieve high reliability even after being left at a high temperature.

The tin or tin alloy forming the solder particles 1 may contain one or more selected from Ag, Cu, Ni, Bi, Zn, Pd, Pb, Au, P and B. Among these elements, Ag or Cu may be included from the following viewpoints. That is, since the solder particles 1 contain Ag or Cu, the melting point of the solder particles 1 can be lowered to about 220° C., and the bonding strength with the electrodes is improved, thereby obtaining good conduction reliability. is played.

The Cu content of the solder particles 1 is, for example, 0.05 to 10% by mass, and may be 0.1 to 5% by mass or 0.2 to 3% by mass. If the Cu content is 0.05% by mass or more, it is easy to obtain good solder connection reliability, while if it is 10% by mass or less, the melting point is lowered, the wettability of the solder is improved, and as a result, the bonding The connection reliability of the part tends to be good.

The Ag content of the solder particles 1 is, for example, 0.05-10% by mass, and may be 0.1-5% by mass or 0.2-3% by mass. If the Ag content is 0.05% by mass or more, it is easy to obtain good solder connection reliability, while if it is 10% by mass or less, the melting point is lowered, the wettability of the solder is improved, and as a result, the bonding The connection reliability of the part tends to be good.

(insulating film)
A thermosetting compound can be used as an adhesive component that constitutes the insulating film 2 . Examples of thermosetting compounds include oxetane compounds, epoxy compounds, episulfide compounds, (meth)acrylic compounds, phenol compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds and polyimide compounds. Among these, epoxy compounds are preferable from the viewpoint of further improving the curability and viscosity of the insulating resin and further increasing the connection reliability.

The adhesive component may further include a thermosetting agent. Examples of thermal curing agents include imidazole curing agents, amine curing agents, phenol curing agents, polythiol curing agents, acid anhydrides, thermal cationic initiators and thermal radical generators. These may be used individually by 1 type, and may use 2 or more types together. Among these, the imidazole curing agent, the polythiol curing agent, or the amine curing agent is preferable because it can be rapidly cured at a low temperature. In addition, a latent curing agent is preferable because storage stability is enhanced when the thermosetting compound and the thermosetting agent are mixed. The latent curing agent is preferably a latent imidazole curing agent, a latent polythiol curing agent or a latent amine curing agent. The thermosetting agent may be coated with a polymeric material such as polyurethane resin or polyester resin.

The imidazole curing agent is not particularly limited. 4-diamino-6-[2′-methylimidazolyl-(1′)]-ethyl-s-triazine and 2,4-diamino-6-[2′-methylimidazolyl-(1′)]-ethyl-s- Triazine isocyanuric acid adducts and the like can be mentioned.

The polythiol curing agent is not particularly limited, and includes trimethylolpropane tris-3-mercaptopropionate, pentaerythritol tetrakis-3-mercaptopropionate and dipentaerythritol hexa-3-mercaptopropionate. . The solubility parameter of the polythiol curing agent is preferably 9.5 or higher and preferably 12 or lower. The solubility parameter is calculated by the Fedors method. For example, trimethylolpropane tris-3-mercaptopropionate has a solubility parameter of 9.6 and dipentaerythritol hexa-3-mercaptopropionate has a solubility parameter of 11.4.

The amine curing agent is not particularly limited, and hexamethylenediamine, octamethylenediamine, decamethylenediamine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraspiro [5.5] undecane, bis(4-aminocyclohexyl)methane, metaphenylenediamine, diaminodiphenylsulfone and the like.

Examples of the thermal cationic curing agent include iodonium-based cationic curing agents, oxonium-based cationic curing agents, and sulfonium-based cationic curing agents. Examples of the iodonium cationic curing agent include bis(4-tert-butylphenyl)iodonium hexafluorophosphate. Examples of the oxonium cationic curing agent include trimethyloxonium tetrafluoroborate. Examples of the sulfonium cationic curing agent include tri-p-tolylsulfonium hexafluorophosphate.

The thermal radical generator is not particularly limited, and includes azo compounds, organic peroxides, and the like. Examples of the azo compound include azobisisobutyronitrile (AIBN). Examples of the organic peroxide include di-tert-butyl peroxide and methyl ethyl ketone peroxide.

(flux)
The anisotropic conductive films 10, 20 preferably contain flux. Specifically, it is preferable that the adhesive components constituting the anisotropic conductive films 10 and 20 contain flux and that the surfaces of the solder particles 1 are covered with the flux. The flux melts oxides on the surface of the solder, fuses the particles together, and improves the wettability of the solder to the electrode.

Flux that is generally used for soldering or the like can be used. Specific examples include zinc chloride, mixtures of zinc chloride and inorganic halides, mixtures of zinc chloride and inorganic acids, molten salts, phosphoric acid, phosphoric acid derivatives, organic halides, hydrazine, organic acids and rosin. mentioned. These may be used individually by 1 type, and may use 2 or more types together.

Molten salts include ammonium chloride and the like. Organic acids include lactic acid, citric acid, stearic acid, glutamic acid and glutaric acid. Examples of rosin include activated rosin and non-activated rosin. Pine resin is a rosin whose main component is abietic acid. By using an organic acid or rosin having two or more carboxyl groups as the flux, the effect of further increasing the reliability of electrical connection between the electrodes is exhibited.

The melting point of the flux is preferably 50°C or higher, more preferably 70°C or higher, and even more preferably 80°C or higher. The melting point of the flux is preferably 200° C. or lower, more preferably 160° C. or lower, still more preferably 150° C. or lower, and particularly preferably 140° C. or lower. When the melting point of the flux is equal to or higher than the lower limit and equal to or lower than the upper limit, the flux effect is exhibited more effectively, and the solder particles are arranged on the electrode more efficiently. The melting point range of the flux is preferably 80 to 190°C, more preferably 80 to 140°C or less.

Fluxes with a melting point in the range of 80 to 190°C include succinic acid (melting point 186°C), glutaric acid (melting point 96°C), adipic acid (melting point 152°C), pimelic acid (melting point 104°C), and suberic acid (melting point 104°C). 142° C.), benzoic acid (melting point 122° C.), malic acid (melting point 130° C.), and the like.

<Method for producing anisotropic conductive film>
A method for manufacturing the <anisotropic conductive film 10 will be described with reference to FIGS.

First, a transfer mold 60 for arranging solder particles 1 is prepared. 5(a) is a plan view of the transfer mold 60, and FIG. 5(b) is a cross-sectional view taken along line bb shown in FIG. 5(a). FIG. 6 is a cross-sectional view showing a state in which solder particles 1 are accommodated one by one in a plurality of recesses 62 (openings) of the transfer mold 60. As shown in FIG.

The concave portion 62 of the transfer mold 60 is preferably formed in a tapered shape in which the opening area increases from the bottom portion 62a side of the concave portion 62 toward the surface 60a side of the transfer mold 60 . That is, as shown in FIGS. 5A and 5B, the width of the bottom 62a of the recess 62 (the width a in these figures) is the width of the opening in the surface 60a of the recess 62 (the width It is preferably narrower than b). The size (taper angle and depth) of the recesses 62 may be set according to the size of the solder particles 1 accommodated in the recesses 62 .

Examples of materials that can be used for the transfer mold 60 include inorganic materials such as silicon, various ceramics, glass, and metals such as stainless steel, and organic materials such as various resins. Among these, from the viewpoint of holding the solder particles 1 in the recessed portions 62, it is preferable that the recessed portions 62 be made of a flexible resin material. The recesses 62 of the transfer mold 60 can be formed by a known method such as photolithography. It should be noted that the transfer mold 60 is preferably made of a material having chemical resistance and heat resistance, because the transfer mold 60 comes into contact with a thermosetting resin or the like and may be subjected to heat for curing the resin.

By using the transfer mold 60, even if the particle size distribution of the solder particles 1 has a certain width, a plurality of solder particles 1 having a narrower particle size distribution width than the solder particles 1 can be easily selected, and these solder particles 1 can be transferred to the anisotropic conductive layer. It can be used in the production of film 10. That is, even if the solder particles 1 smaller than the size of the recesses 62 of the transfer mold 60 are once accommodated in the recesses 62, they will fall if the surface on which the recesses 62 are formed is turned downward, while the solder particles 1 that are smaller than the size of the recesses 62 will fall. Larger solder particles 1 are not accommodated in the recesses 62 .

The anisotropic conductive film 10 is manufactured using a transfer mold 60 capable of accommodating solder particles 1 in recesses 62 . That is, the manufacturing method of the anisotropic conductive film 10 includes the following steps in this order.
(a1) A step of accommodating one solder particle 1 in each concave portion 62 of the transfer mold 60 .
(b1) A step of obtaining a first film 2b onto which a plurality of solder particles 1 have been transferred by bringing the film 2a made of the adhesive component into contact with the side of the transfer mold 60 on which the concave portions 62 are provided.
(c1) An anisotropic conductive film 10 is obtained by forming a second film 2d made of the adhesive component on the surface 2c of the first film 2b on which the plurality of solder particles 1 are transferred. process.

The transfer mold 60 shown in FIG. 7A is in a state after step (a1), in which one solder particle 1 is accommodated in each of the plurality of recesses 62. As shown in FIG. While maintaining this state, the surface 60a of the transfer mold 60 on which the concave portions 62 are formed is directed toward the film 2a made of the adhesive component, and the transfer mold 60 and the film 2a are brought closer (arrow in FIG. 7A). A, B). The film 2a is formed on the surface of the support 65. As shown in FIG. The support 65 may be a plastic film or metal foil.

FIG. 7(b) shows the state after the step (b1), in which the surface 60a of the transfer mold 60 on which the recesses 62 are formed is brought into contact with the film 2a, so that the film is accommodated in the recesses 62 of the transfer mold 60. It shows a state in which the solder particles 1 that had been formed are transferred to the film 2a. Through the step (b1), a first film 2b composed of the film 2a and a plurality of solder particles 1 arranged at predetermined positions on the film 2a is obtained. A plurality of solder particles 1 are exposed on the surface of the first film 2b.

FIG. 7(c) shows the state after step (c1), in which the second film 2d is formed on the surface 2c of the first film 2b so as to cover the solder particles 1, and then the support 65 is attached. It shows removed. Thereby, the anisotropic conductive film 10 is obtained. The second film 2d may be formed by laminating an insulating film made of an adhesive component to the first film 2b, or the first film 2b may be coated with a varnish containing an adhesive component. After that, it may be formed by performing a curing treatment.

Next, a method for manufacturing the anisotropic conductive film 20 will be described with reference to FIGS. The anisotropic conductive film 20 is the same as the anisotropic conductive film 10 except that instead of accommodating one solder particle 1 in each recess 62 of the transfer mold 60, a plurality of solder particles 1 are accommodated. Manufactured in the same manner. In the transfer mold 60 shown in FIG. 8, the cross section of the opening of the concave portion 62 is circular and tapered. That is, the diameter of the bottom of the recess 62 (diameter a in FIG. 8) is set smaller than the diameter of the opening of the recess 62 (diameter b in FIG. 8).

The manufacturing method of the anisotropic conductive film 20 includes the following steps in this order.
(a2) a step of accommodating a plurality of solder particles 1 in each concave portion 62 of the transfer mold 60;
(b2) A first film 2b onto which the particle groups 1A made up of a plurality of solder particles 1 are transferred by bringing the film 2a made of the adhesive component into contact with the side of the transfer mold 60 on which the concave portions 62 are provided. The process of obtaining
(c2) An anisotropic conductive film 20 is obtained by forming a second film 2e composed of the adhesive component on the surface 2c of the first film 2b on the side to which the plurality of particle groups 1A are transferred. process.

FIG. 8(a) is a cross-sectional view schematically showing a state after step (a2), in which a plurality of solder particles 1 are accommodated in recesses 62 of a transfer mold 60, and FIG. 8(b). is a plan view thereof. The number of solder particles 1 accommodated in one recess 62 may be appropriately set according to the particle size of the solder particles 1 and the size of the recess 62. For example, the number may be 1 to 12, or 2 to 8. good too.

As shown in FIG. 9( a ), the surface 60 a of the transfer mold 60 on which the recesses 62 are formed is covered with a film made of the adhesive component while maintaining the state in which the plurality of solder particles 1 are accommodated in the recesses 62 . 2a, the transfer mold 60 and the film 2a are brought closer (arrows A and B in FIG. 9(a)). When the transfer mold 60 is turned upside down from the state shown in FIG. 8(a), the solder particles 1 fall from the recesses 62, so that the plurality of solder particles 1 accommodated in the recesses 62 are removed from the state shown in FIG. 8(a). ) is preferred to be maintained.

FIG. 9(b) shows the state after the step (b2), in which the surface 60a of the transfer mold 60 on which the recesses 62 are formed is brought into contact with the film 2a, so that the film is accommodated in the recesses 62 of the transfer mold 60. It shows a state in which the particle group 1A that had been formed is transferred to the film 2a. Through step (b2), a first film 2b having a plurality of particle groups 1A arranged at predetermined positions is obtained. A plurality of convex portions 2e corresponding to the concave portions 62 are formed on the surface 2c side of the first film 2b, and the particle groups 1A are embedded in these convex portions 2e. In order to obtain the first film 2b having such a structure, the adhesive component should be allowed to penetrate into the recesses 62 in the step (b2). Specifically, it is preferable to apply pressure in order that the adhesive component may enter the recesses 62 and fix the plurality of solder particles 1 (particle groups 1A). Furthermore, by applying pressure while depressurizing, the adhesive component can easily enter the concave portion 62, so this method is more preferable. Further, instead of the film 2a made of an adhesive component, a varnish containing an adhesive component may be placed in the recesses 62 and then cured.

FIG. 9(c) shows the state after step (c2), in which the support 65 is removed after the second film 2e is formed on the surface 2c of the first film 2b. . Thereby, the anisotropic conductive film 20 is obtained. The second film 2e may be formed by laminating an insulating film made of an adhesive component to the first film 2b, or the first film 2b may be coated with a varnish containing an adhesive component. After that, it may be formed by performing a curing treatment.

<Connection structure>
FIG. 10 is a cross-sectional view schematically showing an enlarged part of the connection structure 50A according to this embodiment. That is, the figure schematically shows a state in which the electrodes 32 of the first circuit member 30 and the electrodes 42 of the second circuit member 40 are electrically connected via the solder layer 70 formed by fusion bonding. is shown. In the present specification, "fusion" means that at least a part of the first metal layer 3a is joined by the solder particles 1 melted by heat, and then solidified on the surface of the electrode as described above. This means a soldered state. The first circuit member 30 comprises a first circuit board 31 and a first electrode 32 arranged on its surface 31a. The second circuit member 40 comprises a second circuit board 41 and a second electrode 42 arranged on its surface 41a. The insulating resin layer 55 filled between the circuit members 30 and 40 maintains the state in which the first circuit member 30 and the second circuit member 40 are adhered, and the first electrode 32 and the second electrode. 42 remain electrically connected.

Specific examples of one of the circuit members 30 and 40 include IC chips (semiconductor chips), resistor chips, capacitor chips, chip components such as driver ICs, and rigid package substrates. These circuit members have circuit electrodes, and generally have a large number of circuit electrodes. Other specific examples of the circuit members 30 and 40 include wiring boards such as a flexible tape board having metal wiring, a flexible printed wiring board, and a glass board on which indium tin oxide (ITO) is vapor-deposited.

Specific examples of the first electrode 32 or the second electrode 42 include copper, copper/nickel, copper/nickel/gold, copper/nickel/palladium, copper/nickel/palladium/gold, copper/nickel/gold, copper /palladium, copper/palladium/gold, copper/tin, copper/silver, and indium tin oxide. The first electrode 32 or the second electrode 42 can be formed by electroless plating, electrolytic plating, or sputtering.

FIG. 11 is a cross-sectional view schematically showing a connection structure 50B that is a modification of the connection structure 50A shown in FIG. In connection structure 50B, solder layer 70 is partially fused to electrode 32 of first circuit member 30 and electrode 42 of second circuit member 40 .

FIG. 12 is a cross-sectional view schematically showing a connection structure 50C that is a modification of the connection structure 50A shown in FIG. This figure shows the cross section of the electrode part after the first electrode 32 and the second electrode 42 are made of copper, especially after being left at a high temperature. A layer 71 made of an intermetallic compound is formed by being left at a high temperature.

FIG. 13 is a cross-sectional view schematically showing a connection structure 50D that is a modification of the connection structure 50A shown in FIG. This figure shows the cross section of the electrode part after the first electrode 32 and the second electrode 42 are made of copper, especially after being left at a high temperature. A layer 71 made of an intermetallic compound is formed by being left at a high temperature. FIG. 13 shows that the intermetallic compound layer 71 was formed thicker by being left at a high temperature than in FIG.

FIG. 14 is a cross-sectional view schematically showing a connection structure 50E that is a modification of the connection structure 50A shown in FIG. This figure shows the cross section of the electrode part after the first electrode 32 and the second electrode 42 are made of copper, especially after being left at a high temperature. A layer 71 made of an intermetallic compound is formed by being left at a high temperature. FIG. 14 shows a case where the thickness of the solder layer 70 formed between the first electrode 32 and the second electrode 42 is thinner than in FIG.

FIG. 15 is a cross-sectional view schematically showing a connection structure 50F that is a modification of the connection structure 50A shown in FIG. This figure shows the case where the first electrode 32 and the second electrode 42 are made of copper, and shows the cross section of the electrode part after being left at a high temperature in FIG. A layer 71 made of an intermetallic compound is formed by being left at a high temperature. In this case, all the solder layers are transformed into intermetallic compounds, indicating that a thin intermetallic compound layer 71 is formed. FIG. 15 shows that the thickness of the original solder layer formed between the first electrode 32 or the second electrode 42 is thinner than that of FIG. , the intermetallic compound layer 71 is thin. In general, if the intermetallic compound layer is thick, reliability tends to decrease when an impact such as a drop impact is applied. , high reliability can be maintained even if a drop impact is applied. The thickness of the intermetallic compound layer 71 is preferably 0.1 to 10.0 μm, more preferably 0.3 to 8.0 μm, even more preferably 0.5 to 6.0 μm.

<Method for manufacturing connection structure>
A method for manufacturing a connection structure will be described with reference to FIGS. 16(a) and 16(b). These figures are cross-sectional views schematically showing an example of the process of forming the connection structure 50A shown in FIG. First, the anisotropic conductive film 10 shown in FIG. 1 is prepared in advance and arranged so that the first circuit member 30 and the second circuit member 40 face each other (FIG. 16(a)). At this time, the first electrode 32 of the first circuit member 30 and the second electrode 42 of the second circuit member 40 are installed so as to face each other. Thereafter, pressure is applied in the thickness direction of the laminate of these members (in the directions of arrows A and B shown in FIG. 16(a)). By heating at least the whole to a temperature higher than the melting point of the solder particles 1 (for example, 130 to 260° C.) when pressurizing in the directions of arrows A and B, the solder particles 1 are melted, and the first electrode 32 and the Gathering between the second electrodes 42, a solder layer 70 is formed and then cooled to affix the solder layer 70 between the first electrode 32 and the second electrode 42, forming the first electrode. 32 and the second electrode 42 are electrically connected.

If the insulating film 2 is made of, for example, a thermosetting resin, the thermosetting resin can be cured by heating the entire film when applying pressure in the directions of arrows A and B. As shown in FIG. As a result, an insulating resin layer 55 made of a cured thermosetting resin is formed between the circuit members 30 and 40 .

17A and 17B are cross-sectional views schematically showing a modification of the manufacturing method of the connection structure 50A shown in FIG. In the manufacturing method according to this modification, although some of the solder particles 1 remain in the insulating resin layer 55 without contributing to the fusion of the electrodes 32 and 42, the anisotropic conductive film 10 has a specific Since the solder particles 1 are only arranged at the positions, that is, the density of the solder particles 1 is sufficiently low, the insulation reliability can be maintained high.

18A and 18B are cross-sectional views schematically showing a modification of the manufacturing method of the connection structure 50A shown in FIG. In the manufacturing method according to this modification, substantially all the solder particles 1 become the solder layer 70, and the first electrode 32 of the first circuit member 30 and the second electrode 42 of the second circuit member 40 are formed. It is fused. By designing the arrangement of the solder particles 1 in the anisotropic conductive film 10 in advance, it is possible to minimize the solder particles 1 remaining in the adhesive component without contributing to fusion bonding. Thereby, the insulation reliability of the connection structure can be further improved.

19A and 19B are cross-sectional views schematically showing a modification of the manufacturing method of the connection structure 50A shown in FIG. This modification is the same as the manufacturing method shown in FIG. 16 except that the anisotropic conductive film 20 is used instead of the anisotropic conductive film 10 .

20A to 20C are cross-sectional views schematically showing a modification of the manufacturing method of the connection structure shown in FIG. This modification is the same as the manufacturing method shown in FIG. 17 except that the anisotropic conductive film 20 is used instead of the anisotropic conductive film 10 . Part of the particle group 1A does not contribute to the fusion of the electrodes 32 and 42, and the particle group 1A becomes one solder particle 1B due to thermal history and remains in the insulating resin layer 55. The solder particles 1 are only arranged at specific positions in the anisotropic conductive film 20, that is, the density of the solder particles 1 is sufficiently low, the particle size of the solder particles 1 is sufficiently small, and the solder particles 1B Since the particle size is also sufficiently small, it is possible to maintain high insulation reliability.

21A to 21C are cross-sectional views schematically showing a modification of the manufacturing method of the connection structure shown in FIG. In the manufacturing method according to this modification, almost all the particle groups 1A become the solder layer 70, and the first electrode 32 of the first circuit member 30 and the second electrode 42 of the second circuit member 40 are fused. is doing. By designing the arrangement of the particle groups 1A in the anisotropic conductive film 20 in advance, it is possible to minimize the number of solder particles remaining in the adhesive component without contributing to fusion. Thereby, the insulation reliability of the connection structure can be further improved.

Devices such as liquid crystal displays, personal computers, mobile phones, smart phones, and tablets are examples of application targets of the connection structures according to the above-described embodiments and modifications thereof.

According to the present embodiment, even if the connection area is as small as 16 to 2000 μm ^{2 , 25 to 1600 μm 2 or} 100 to 1000 μm ² , both the insulation reliability and the conduction reliability are excellent, and the connection structure and A method of making the same is provided.

EXAMPLES The content of the present invention will be more specifically described below with reference to examples and comparative examples. In addition, the present invention is not limited to the following examples.

<Example 1>
[Preparation of anisotropic conductive film]
(Step 1) Classification of Solder Particles 100 g of Sn—Bi solder particles (manufactured by 5N Plus, Type 8) having an average particle size of 5.0 μm or less (d90=5 μm) are immersed in distilled water, ultrasonically dispersed, and then After filtration with a φ3 μm membrane filter (manufactured by Merck Ltd.), the filtrate was recovered. After that, the filtrate was centrifuged to recover the solder particles in the aqueous solution. The collected solder particles weighed 10 g and had an average particle size of 1.0 μm.

(Step 2) Placement of solder particles on transfer mold Opening diameter 1.0 μmφ, bottom diameter 0.8 μmφ, depth 1 μm A transfer mold was prepared in which the recesses of 1.0 .mu.m were regularly arranged at intervals of 1.0 .mu.m. A polyimide film (thickness: 100 μm) was used as the transfer type film. Sorted solder particles (average particle size: 1.0 μm) were placed in the recesses of the transfer mold.

(Step 3) Preparation of adhesive film 100 g of phenoxy resin (manufactured by Union Carbide, trade name “PKHC”), acrylic rubber (40 parts by mass of butyl acrylate, 30 parts by mass of ethyl acrylate, 30 parts by mass of acrylonitrile, and 3 parts by mass of glycidyl methacrylate) (molecular weight: 850,000) was dissolved in 400 g of ethyl acetate to obtain a solution. To this solution, 300 g of a liquid epoxy resin containing a microcapsule-type latent curing agent (epoxy equivalent: 185, manufactured by Asahi Kasei Corporation, trade name "Novacure HX-3941") was added and stirred to obtain an adhesive solution. The resulting adhesive solution was applied to a separator (polyethylene terephthalate film treated with silicone, 40 μm thick) using a roll coater and dried by heating at 90° C. for 10 minutes to give thicknesses of 4 μm, 6 μm and An 8 μm adhesive film 1 (corresponding to film 2a) was produced on the separator.

(Step 4) Transfer of Solder Particles to Adhesive Film The solder particles placed in the recesses of the transfer mold and the adhesive film 1 are placed facing each other, and the pressure is 50° C. and 0.01 MPa (0.1 kgf/cm ² ). The solder particles were transferred to the adhesive film 1 by heating and pressurizing with (see FIG. 7B).

(Step 5) Preparation of anisotropic conductive film The adhesive film 1 obtained in Step 3 was brought into contact with the surface of the adhesive film on the side to which the solder particles ^were transferred, and ) to obtain an anisotropic conductive film in which solder particles with an average particle diameter of 1.0 μm are arranged in layers in a cross-sectional view of the film (see FIG. 7C). In addition, an anisotropic conductive film with a thickness of 8 μm, 12 μm, and 16 μm was produced by overlapping 4 μm with a film with a thickness of 4 μm, similarly, with 6 μm with 6 μm, and with 8 μm with 8 μm. did. The locations in the anisotropic conductive film where the solder particles should be arranged include locations where one solder particle is arranged and locations where a particle group consisting of a plurality of solder particles is arranged. The average number of solder particles was 1.2.

[Production of connection structure]
(Step 6) Preparation of Chips with Copper Bumps Five types of chips with copper bumps (1.7×1.7 mm, thickness: 0.5 mm) shown below were prepared.
(1) Chip C1: area 30 μm×30 μm, space 30 μm, height: 10 μm, number of bumps 362, number of conductive particles on copper bumps 8
(2) Chip C2: area 15 μm×15 μm, space 10 μm, height: 10 μm, number of bumps 362, number of conductive particles on copper bumps 8
(3) Chip C3: area 10 μm×10 μm, space 10 μm, height: 7 μm, number of bumps 362, number of conductive particles on copper bumps 4
(4) Chip C4: area 5 μm×5 μm, space 6 μm, height: 5 μm, number of bumps 362, number of conductive particles on copper bumps 8
(5) Chip C5: area 3 μm×3 μm, space 3 μm, height: 5 μm, number of bumps 362, number of conductive particles on copper bumps 8

(Step 7) Preparation of substrates with copper bumps Five types of substrates with copper bumps (thickness: 0.7 mm) shown below were prepared.
(1) Substrate D1: area 30 μm×30 μm, space 30 μm, height: 10 μm, number of bumps 362, number of conductive particles on copper bumps 8
(2) Substrate D2: area 15 μm×15 μm, space 10 μm, height: 10 μm, number of bumps 362, number of conductive particles on copper bumps 8
(3) Substrate D3: area 10 μm×10 μm, space 10 μm, height: 7 μm, number of bumps 362, number of conductive particles on copper bumps 4
(4) Substrate D4: area 5 μm×5 μm, space 6 μm, height 5 μm, number of bumps 362, number of conductive particles on copper bumps 8
(5) Substrate D5: area 3 μm×3 μm, space 3 μm, height: 5 μm, number of bumps 362, number of conductive particles on copper bumps 8

(Step 8) Production of connection structure Next, using the produced anisotropic conductive film, a chip with copper bumps (1.7 × 1.7 mm, thickness: 0.5 mm) and a substrate with copper bumps ( Thickness: 0.7 mm), and a connection structure was obtained by performing connection according to the following procedures i) to iii).
i) Peel off the separator (silicone-treated polyethylene terephthalate film, 40 μm thick) on one side of the anisotropic conductive film (2×19 mm), bring the anisotropic conductive film and the substrate with copper bumps into contact, and heat at 80° C., 0.000. It was attached at 98 MPa (10 kgf/cm ² ).
ii) The separator was peeled off, and the bumps of the chip with copper bumps and the bumps of the substrate with copper bumps were aligned.
iii) Heating and pressure were applied from above the chip under the conditions of 180° C., 40 gf/bump, and 30 seconds to effect final connection. A total of five types of connection structures according to (1) to (5) were produced using the following combinations of "chip/anisotropic conductive film/substrate" (1) to (5).
(1) chip C1/16 μm thick anisotropic conductive film/substrate D1,
(2) chip C2/16 μm thick anisotropic conductive film/substrate D2;
(3) chip C3/12 μm thick anisotropic conductive film/substrate D3,
(4) chip C4/8 μm thick anisotropic conductive film/substrate D4,
(5) chip C5/8 μm thick anisotropic conductive film/substrate D5,

[Evaluation of connection structure]
Conduction resistance test and insulation resistance test of the obtained connection structure were performed as follows.

(Continuity resistance test - Moisture absorption and heat resistance test)
Regarding the conduction resistance between a chip with copper bumps (bumps) and a substrate with copper bumps (bumps), the initial value of conduction resistance and after a moisture absorption and heat resistance test (left at 85°C and 85% humidity for 100, 500, and 1000 hours) was measured for 20 samples, and their average value was calculated. The above-described connection structure in which the chip C1 and the substrate D1, the chip C2 and the substrate D2, the chip C3 and the substrate D3, the chip C4 and the substrate D4, and the chip C5 and the substrate D5 are combined and connected was used for evaluation. Conduction resistance was evaluated from the obtained average values according to the following criteria. Table 1 shows the results. Incidentally, when the following criterion A or B is satisfied after 1000 hours of the moisture absorption and heat resistance test, it can be said that the conduction resistance is good.
A: Average conduction resistance less than 2 Ω B: Average conduction resistance 2 Ω or more and less than 5 Ω C: Average conduction resistance 5 Ω or more and less than 10 Ω D: Average conduction resistance 10 Ω or more and less than 20 Ω E: Conduction resistance average value of 20Ω or more

(Continuity resistance test - High temperature storage test)
Conductive resistance between a chip with copper bumps (bumps) and a substrate with copper bumps (bumps) was measured for samples before high temperature exposure and after high temperature exposure tests (left at 100°C for 100, 500, and 1000 hours). . After being left at high temperature, a drop impact was applied, and the conduction resistance of the sample after the drop impact was measured. The drop impact was obtained by fixing the connection structure to a metal plate with screws and dropping it from a height of 50 cm. After the drop, the DC resistance value was measured at the solder joints (four points) at the chip corners where the impact was the greatest, and when the measured value increased by 5 times or more from the initial resistance, it was considered that a fracture had occurred, and evaluation was performed. In addition, 20 samples were measured at 4 points, totaling 80 points. Table 1 shows the results. Solder connection reliability was evaluated to be good when the following criterion A or B was satisfied after 20 drops. "-" in the table means that the evaluation was not performed.
A: After being dropped 20 times, no soldered joints that increased the initial resistance by a factor of 5 or more were observed at any of the 80 locations.
B: After being dropped 20 times, solder joints with an increase in initial resistance of 5 times or more were found at 1 or more and 5 or less locations.
C: After 20 drops, 6 to 20 soldered joints increased in resistance by a factor of 5 or more from the initial resistance.
D: After 20 drops, 21 or more soldered joints increased the initial resistance by 5 times or more.

(insulation resistance test)
Regarding the insulation resistance between the chip electrodes, the initial value of the insulation resistance and the value after the migration test (100, 500, 1000 hours under the conditions of temperature 60 ° C., humidity 90%, 20 V application) were measured for 20 samples, The proportion of samples with an insulation resistance value of 10 ⁹ Ω or higher among all 20 samples was calculated. Evaluation was made using a connection structure in which chip C1 and substrate D1, chip C2 and substrate D2, chip C3 and substrate D3, chip C4 and substrate D4, and chip C5 and substrate D5 were combined and connected. The insulation resistance was evaluated from the obtained ratio according to the following criteria. Table 2 shows the results. In addition, when the following standard A or B is satisfied after 1000 hours of the moisture absorption and heat resistance test, it can be said that the insulation resistance is good.
A: 100% of the insulation resistance value is 10 ⁹ Ω or more
B: 90% or more and less than 100% of the insulation resistance value is 10 ⁹ Ω or more C: 80% or more and less than 90% of the insulation resistance value is 10 ⁹ Ω or more D: 50% of the insulation resistance value is 10 ⁹ Ω or more More than 80% E: Less than 50% of the insulation resistance value is 10 ⁹ Ω or more

<Example 2>
In the same manner as in (step 1) of Example 1, 100 g of Sn—Bi solder particles (manufactured by 5N Plus, Type 8) having an average particle size of 5.0 μm or less (d90=5 μm) were immersed in distilled water, and then subjected to ultrasonic wave. After being dispersed and then filtered through a φ1.2 μm membrane filter (manufactured by Merck Ltd.), the filtrate was collected. After that, the filtrate was centrifuged to recover the solder particles in the aqueous solution. The collected solder particles weighed 7 g and had an average particle size of 0.8 μm.
Subsequently, (Step 2) and (Step 3) of Example 1 were performed. At this time, a plurality of solder particles were accommodated in the recesses of the transfer mold. In (Step 4), by changing the pressure to 0.1 MPa (1.0 kgf/cm ² ) and applying pressure, the adhesive component of the adhesive film enters into the recesses, and a plurality of solder particles are applied to the adhesive film. It was immobilized (see FIG. 9(b)).
Subsequently, (Step 5) of Example 1 was carried out to obtain an anisotropic conductive film in which particle groups composed of a plurality of solder particles were arranged in layers (see FIG. 9C). The average number of solder particles forming the particle group was 2.5. The connection structure was evaluated in the same manner as in Example 1. Table 2 shows the results.

<Example 3>
In the same manner as in (step 1) of Example 1, 100 g of Sn—Bi solder particles (manufactured by 5N Plus, Type 8) having an average particle size of 5.0 μm or less (d90=5 μm) were immersed in distilled water, and then subjected to ultrasonic wave. After being dispersed and then filtered through a φ0.8 μm membrane filter (manufactured by Merck Ltd.), the filtrate was collected. After that, the filtrate was centrifuged to recover the solder particles in the aqueous solution. The collected solder particles weighed 5 g and had an average particle size of 0.6 μm.
Subsequently, (Step 2) and (Step 3) of Example 1 were performed. At this time, a plurality of solder particles were accommodated in the recesses of the transfer mold. In (Step 4), by changing the pressure to 0.1 MPa (1.0 kgf/cm ² ) and applying pressure, the adhesive component of the adhesive film enters into the recesses, and a plurality of solder particles are applied to the adhesive film. It was immobilized (see FIG. 9(b)).
Subsequently, (step e) of Example 1 was performed to obtain an anisotropic conductive film in which particle groups composed of a plurality of solder particles were arranged in layers (see FIG. 9C). The average number of solder particles forming the particle group was 5.1. The connection structure was evaluated in the same manner as in Example 1. Table 3 shows the results.

<Example 4>
Except for using a transfer mold with the same concave shape (opening 1.0 μm) and a space of 2.0 μm as in (Step 2) of Example 1, the density of the concave portions is reduced. produced an anisotropic conductive film in the same manner as in Example 1, produced a connection structure using these films, and evaluated them. Table 4 shows the results.

<Example 5>
The solder particles obtained in the same manner as in (Step 1) of Example 1 are placed on the transfer mold having an opening diameter of 1.0 μmφ in (Step 2) of Example 1, and the solder particles on the transfer mold are traced with a brush. Solder particles having a diameter of 1.0 μmφ or less were thus collected in the concave portions. The average particle diameter of the solder particles that remained without being collected was 1.9 μm.
Subsequently, a recess with an opening diameter of 2.0 μmφ, a bottom diameter of 1.8 μmφ, and a depth of 2 μm (the bottom diameter of 1.8 μmφ is located in the center of the opening diameter of 2.0 μmφ when viewed from above). A transfer mold was prepared which was regularly arranged with a space interval of 2.0 μm. A polyimide film (thickness: 100 μm) was used as the transfer type film. Solder particles having an average particle size of 1.9 μm were arranged in the recesses of the transfer mold.
Subsequently, by performing (process 3) and subsequent steps in the same manner as in Example 1, an anisotropic conductive film in which solder particles were substantially single and arranged in layers was obtained (see FIG. 7C). The average number of solder particles per location where solder particles should be arranged in the anisotropic conductive film was 1.1. The connection structure was evaluated in the same manner as in Example 1. Table 5 shows the results.

<Example 6>
The solder particles obtained in the same manner as in (Step 1) of Example 1 are placed on the transfer mold having an opening diameter of 1.0 μmφ in (Step 2) of Example 1, and the solder particles on the transfer mold are traced with a brush. Solder particles having a diameter of 1.0 μmφ or less were thus collected in the concave portions. The average particle size of the solder particles that remained without being collected was 1.6 μm.
Subsequently, a recess with an opening diameter of 2.0 μmφ, a bottom diameter of 1.8 μmφ, and a depth of 2 μm (the bottom diameter of 1.8 μmφ is located in the center of the opening diameter of 2.0 μmφ when viewed from above). A transfer mold was prepared which was regularly arranged with a space interval of 2.0 μm. A polyimide film (thickness: 100 μm) was used as the transfer type film. Solder particles having an average particle size of 1.6 μm were arranged in the recesses of the transfer mold.
Subsequently, after carrying out in the same manner as in (Step 3) of Example 1, in (Step 4) of Example 1, by changing the pressure to 0.1 MPa (1.0 kgf/cm ² ) and pressurizing, The adhesive component of the adhesive film was introduced into the recesses to fix a plurality of solder particles to the adhesive film (see FIG. 9(b)).
Subsequently, (Step 5) of Example 1 was carried out to obtain an anisotropic conductive film in which particle groups composed of a plurality of solder particles were arranged in layers (see FIG. 9C). The average number of solder particles forming the particle group was 2.5. The connection structure was evaluated in the same manner as in Example 1. Table 6 shows the results.

<Example 7>
The solder particles obtained in the same manner as in (Step 1) of Example 1 are placed in the transfer mold having an opening diameter of 1.0 μmφ in (Step 2) of Example 1, and the solder particles on the transfer mold are brushed. By tracing with a hand, solder particles having a diameter of 1.0 μmφ or less were collected in the concave portions. The average particle size of the solder particles that remained without being collected was 1.3 μm.
Subsequently, a recess with an opening diameter of 2.0 μmφ, a bottom diameter of 1.8 μmφ, and a depth of 2 μm (the bottom diameter of 1.8 μmφ is located in the center of the opening diameter of 2.0 μmφ when viewed from above). A transfer mold was prepared which was regularly arranged with a space interval of 2.0 μm. A polyimide film (thickness: 100 μm) was used as the transfer type film. Solder particles having an average particle size of 1.3 μm were arranged in the recesses of the transfer mold.
After carrying out in the same manner as in (Step 3) of Example 1, in (Step 4) of Example 1, the pressure was changed to 0.1 MPa (1.0 kgf/cm ² ) to pressurize the adhesive film. An adhesive component was allowed to enter the recesses to fix a plurality of solder particles to the adhesive film (see FIG. 9(b)).
Subsequently, (Step 5) of Example 1 was carried out to obtain an anisotropic conductive film in which particle groups composed of a plurality of solder particles were arranged in layers (see FIG. 9C). The average number of solder particles forming the particle group was 4.5. The connection structure was evaluated in the same manner as in Example 1. Table 7 shows the results.

<Example 8>
In the same manner as in (step 1) of Example 1, 100 g of Sn—Bi solder particles (manufactured by 5N Plus, Type 8) having an average particle size of 5.0 μm or less (d90=5 μm) were immersed in distilled water, and then subjected to ultrasonic wave. After being dispersed and then filtered through a φ5 μm membrane filter (manufactured by Merck Ltd.), the filtrate was collected. After that, the filtrate was centrifuged to recover the solder particles in the aqueous solution. The collected solder particles were 20 g.
The obtained solder particles have an opening diameter of 2.0 μmφ, a bottom diameter of 1.8 μmφ, and a depth of 2 μm (the bottom diameter of 1.8 μmφ is located in the center of the opening diameter of 2.0 μmφ when the recess is viewed from above. ) was placed in the transfer mold. By tracing the solder particles on the transfer mold with a brush, solder particles having a diameter of 2.0 μmφ or less were collected in the concave portions. The average particle size of the solder particles that remained without being collected was 2.8 μm.
Subsequently, a recess with an opening diameter of 3.0 μmφ, a bottom diameter of 2.5 μmφ, and a depth of 3 μm (the bottom diameter of 2.5 μmφ is located in the center of the opening diameter of 3.0 μmφ when viewed from above). A transfer mold was prepared which was regularly arranged with a space interval of 3.0 μm. A polyimide film (thickness: 100 μm) was used as the transfer type film. Solder particles having an average particle size of 2.8 μm were arranged in the recesses of the transfer mold.
Subsequently, by performing (process 3) and subsequent steps in the same manner as in Example 1, an anisotropic conductive film in which solder particles were substantially single and arranged in layers was obtained (see FIG. 7C). The average number of solder particles per location where solder particles should be arranged in the anisotropic conductive film was 1.3. The connection structure was evaluated in the same manner as in Example 1. Table 8 shows the results.

<Example 9>
The solder particles obtained in the same manner as in (Step 1) of Example 1 are placed in a transfer mold having an opening diameter of 2.0 μmφ in (Step 2) of Example 1, and the solder particles on the transfer mold are traced with a brush. Solder particles having a diameter of 2.0 μmφ or less were thus collected in the concave portions. The average particle size of the solder particles that remained without being collected was 2.5 μm.
Subsequently, a recess with an opening diameter of 3.0 μmφ, a bottom diameter of 2.5 μmφ, and a depth of 3 μm (the bottom diameter of 2.5 μmφ is located in the center of the opening diameter of 3.0 μmφ when viewed from above). A transfer mold was prepared which was regularly arranged with a space interval of 3.0 μm. A polyimide film (thickness: 100 μm) was used as the transfer type film. Solder particles having an average particle size of 2.5 μm were arranged in the recesses of the transfer mold.
Subsequently, after carrying out in the same manner as in (Step 3) of Example 1, in (Step 4) of Example 1, by changing the pressure to 0.1 MPa (1.0 kgf/cm ² ) and pressurizing, The adhesive component of the adhesive film was introduced into the recesses to fix a plurality of solder particles to the adhesive film (see FIG. 9(b)).
Subsequently, (Step 5) of Example 1 was carried out to obtain an anisotropic conductive film in which particle groups composed of a plurality of solder particles were arranged in layers (see FIG. 9C). The average number of solder particles forming the particle group was 2.3. The connection structure was evaluated in the same manner as in Example 1. Table 9 shows the results.

<Example 10>
The solder particles obtained in the same manner as in (Step 1) of Example 1 are placed in a transfer mold having an opening diameter of 2.0 μmφ in (Step 2) of Example 1, and the solder particles on the transfer mold are traced with a brush. Solder particles having a diameter of 2.0 μmφ or less were thus collected in the concave portions. The average particle diameter of the solder particles that remained without being collected was 2.3 μm.
Subsequently, a recess with an opening diameter of 3.0 μmφ, a bottom diameter of 2.5 μmφ, and a depth of 3 μm (the bottom diameter of 2.5 μmφ is located in the center of the opening diameter of 3.0 μmφ when viewed from above). A transfer mold was prepared which was regularly arranged with a space interval of 3.0 μm. A polyimide film (thickness: 100 μm) was used as the transfer type film. Solder particles having an average particle diameter of 2.3 μm were arranged in the recesses of the transfer mold.
Subsequently, after carrying out in the same manner as in (Step 3) of Example 1, in (Step 4) of Example 1, by changing the pressure to 0.1 MPa (1.0 kgf/cm ² ) and pressurizing, The adhesive component of the adhesive film was introduced into the recesses to fix a plurality of solder particles to the adhesive film (see FIG. 9(b)).
Subsequently, (Step 5) of Example 1 was carried out to obtain an anisotropic conductive film in which particle groups composed of a plurality of solder particles were arranged in layers (see FIG. 9C). The average number of solder particles forming the particle group was 4.6. The connection structure was evaluated in the same manner as in Example 1. Table 10 shows the results.

<Example 11>
Using the anisotropic conductive film produced in Example 8, the solder particles formed on the anisotropic conductive film are positioned between the bumps of the chip C5 and the bumps of the substrate D5. A connection structure having the configuration (chip C5/anisotropic conductive film having a thickness of 8 μm/substrate D5) according to (5) was produced. Other than that, the connection structure was evaluated in the same manner as in Example 1 (however, the "continuity resistance test-high temperature exposure test" was not performed). Table 11 shows the results.

<Example 12>
Using the anisotropic conductive film produced in Example 9, the solder particles formed on the anisotropic conductive film are positioned between the bumps of the chip C5 and the bumps of the substrate D5. A connection structure having the configuration according to (5) was produced. Other than that, the connection structure was evaluated in the same manner as in Example 1 (however, the "continuity resistance test-high temperature storage test" was not performed). Table 11 shows the results.

<Example 13>
Using the anisotropic conductive film produced in Example 10, the solder particles formed on the anisotropic conductive film are positioned between the bumps of the chip C5 and the bumps of the substrate D5. A connection structure having the configuration according to (5) was produced. Other than that, the connection structure was evaluated in the same manner as in Example 1 (however, the "continuity resistance test-high temperature storage test" was not performed). Table 11 shows the results.

<Example 14>
100 g of Sn—Bi solder particles (5N Plus, Type 7) with a particle size of 2.0 μm to 14.0 μm or less (d90 = 12 μm) are sieved with a high-precision electroformed sieve (AS ONE Corporation, trade name) with an opening size of 4 μm. and collected those that did not pass. Subsequently, the collected solder particles were sieved with a high-precision electroformed sieve (trade name, AS ONE Corporation) having an opening size of 6 μm, and the solder particles that passed through the sieve were collected.

The resulting solder particles have an opening diameter of 3.0 μmφ, a bottom diameter of 2.5 μmφ, and a depth of 3 μm (the bottom diameter of 2.5 μmφ is positioned at the center of the opening diameter of 3.0 μmφ when the concave portion is viewed from above. ) was placed in a transfer mold having recesses. Then, by tracing the solder particles on the transfer mold with a brush, the solder particles having a diameter of 3.0 μmφ or less were collected in the concave portions. The average particle diameter of the solder particles that remained without being collected was 4.6 μm.
Subsequently, a recess with an opening diameter of 5.0 μmφ, a bottom diameter of 4.0 μmφ, and a depth of 5 μm (the bottom diameter of 4.0 μmφ is located in the center of the opening diameter of 5.0 μmφ when viewed from above). A transfer mold was prepared which was regularly arranged with a space interval of 5.0 μm. A polyimide film (thickness: 100 μm) was used as the transfer type film. Solder particles having an average particle size of 4.6 μm were arranged in the recesses of the transfer mold.

Subsequently, by performing (process 3) and subsequent steps in the same manner as in Example 1, an anisotropic conductive film in which solder particles were substantially single and arranged in layers was obtained (see FIG. 7C). The average number of solder particles per location where solder particles should be arranged in the anisotropic conductive film was 1.2. In the same manner as in Example 1, the following (1) to (4) connection structures were evaluated. Table 12 shows the results.
(1) chip C1/16 μm thick anisotropic conductive film/substrate D1,
(2) chip C2/16 μm thick anisotropic conductive film/substrate D2;
(3) chip C3/12 μm thick anisotropic conductive film/substrate D3;
(4) chip C4/8 μm thick anisotropic conductive film/substrate D4;

<Example 15>
100 g of Sn—Bi solder particles (5N Plus, Type 7) with a particle size of 2.0 μm to 14.0 μm or less (d90 = 12 μm) are sieved with a high-precision electroformed sieve (AS ONE Corporation, trade name) with an opening size of 4 μm. and collected those that did not pass. Subsequently, the collected solder particles were sieved with a high-precision electroformed sieve (trade name, AS ONE Co., Ltd.) with an opening size of 5 μm, and the solder particles that passed through the sieve were collected.

The resulting solder particles have an opening diameter of 3.0 μmφ, a bottom diameter of 2.5 μmφ, and a depth of 3 μm (the bottom diameter of 2.5 μmφ is positioned at the center of the opening diameter of 3.0 μmφ when the concave portion is viewed from above. ) was placed in a transfer mold having recesses. Then, by tracing the solder particles on the transfer mold with a brush, the solder particles having a diameter of 3.0 μmφ or less were collected in the concave portions. The average particle diameter of the solder particles that remained without being collected was 3.7 μm.
Subsequently, a recess with an opening diameter of 5.0 μmφ, a bottom diameter of 4.0 μmφ, and a depth of 5 μm (the bottom diameter of 4.0 μmφ is located in the center of the opening diameter of 5.0 μmφ when viewed from above). A transfer mold was prepared which was regularly arranged with a space interval of 5.0 μm. A polyimide film (thickness: 100 μm) was used as the transfer type film. Solder particles having an average particle size of 3.7 μm were arranged in the recesses of the transfer mold.

Subsequently, after carrying out in the same manner as in (Step 3) of Example 1, in (Step 4) of Example 1, by changing the pressure to 0.1 MPa (1.0 kgf/cm ² ) and pressurizing, The adhesive component of the adhesive film was introduced into the recesses to fix a plurality of solder particles to the adhesive film (see FIG. 9(b)).
Subsequently, (Step 5) of Example 1 was carried out to obtain an anisotropic conductive film in which particle groups composed of a plurality of solder particles were arranged in layers (see FIG. 9C). The average number of solder particles forming the particle group was 3.4. In the same manner as in Example 1, the connection structures having the configurations according to (1) to (4) were evaluated. Table 13 shows the results.

<Example 16>
100 g of Sn—Bi solder particles (5N Plus, Type 7) with a particle size of 2.0 μm to 14.0 μm or less (d90 = 12 μm) are sieved with a high-precision electroformed sieve (AS ONE Corporation, trade name) with an opening size of 4 μm. and collected those that did not pass. Subsequently, the collected solder particles were sieved with a high-precision electroformed sieve (trade name, AS ONE Co., Ltd.) with an opening size of 5 μm, and the solder particles that passed through the sieve were collected.

The resulting solder particles have an opening diameter of 3.0 μmφ, a bottom diameter of 2.5 μmφ, and a depth of 3 μm (the bottom diameter of 2.5 μmφ is positioned at the center of the opening diameter of 3.0 μmφ when the concave portion is viewed from above. ) was placed in a transfer mold having recesses. Then, by tracing the solder particles on the transfer mold with a brush, the solder particles having a diameter of 3.0 μmφ or less were collected in the concave portions. The average particle diameter of the solder particles that remained without being collected was 3.2 μm.
Subsequently, a recess with an opening diameter of 5.0 μmφ, a bottom diameter of 4.0 μmφ, and a depth of 5 μm (the bottom diameter of 4.0 μmφ is located in the center of the opening diameter of 5.0 μmφ when viewed from above). A transfer mold was prepared which was regularly arranged with a space interval of 5.0 μm. A polyimide film (thickness: 100 μm) was used as the transfer type film. Solder particles having an average particle size of 3.2 μm were arranged in the recesses of the transfer mold.

Subsequently, after carrying out in the same manner as in (Step 3) of Example 1, in (Step 4) of Example 1, by changing the pressure to 0.1 MPa (1.0 kgf/cm ² ) and pressurizing, The adhesive component of the adhesive film was introduced into the recesses to fix a plurality of solder particles to the adhesive film (see FIG. 9(b)).
Subsequently, (Step 5) of Example 1 was carried out to obtain an anisotropic conductive film in which particle groups composed of a plurality of solder particles were arranged in layers (see FIG. 9C). The average number of solder particles forming the particle group was 4.2. In the same manner as in Example 1, the connection structures having the configurations according to (1) to (4) were evaluated. Table 14 shows the results.

<Example 17>
Example 14 except that instead of the transfer mold having recesses regularly arranged at intervals of 5.0 μm, a transfer mold having recesses at positions corresponding to the positions and sizes of the bumps was used. An anisotropic conductive film was produced in the same manner as. Note that FIG. 22 is a plan view schematically showing the relationship between the positions of the solder particles of the anisotropic conductive film and the positions of the bumps (30 μm×30 μm in size). FIG. 23 is a plan view schematically showing the relationship between the positions of solder particles on an anisotropic conductive film and the positions of bumps (size 15 μm×15 μm). FIG. 24 is a plan view schematically showing the relationship between the positions of solder particles on an anisotropic conductive film and the positions of bumps (10 μm×10 μm in size). FIG. 25 is a plan view schematically showing the relationship between the positions of solder particles on an anisotropic conductive film and the positions of bumps (size 5 μm×5 μm).
Using the produced anisotropic conductive film, the connection structures according to (1) to (4) were evaluated in the same manner as in Example 1. Table 15 shows the results.

<Example 18>
Example 15 except that instead of the transfer mold in which the recesses were regularly arranged at intervals of 5.0 μm, a transfer mold having recesses at positions corresponding to the positions and sizes of the bumps was used. An anisotropic conductive film was produced in the same manner (see FIGS. 22 to 25). Using the produced anisotropic conductive film, the connection structures according to (1) to (4) were evaluated in the same manner as in Example 1. Table 16 shows the results.

<Example 19>
Example 16 except that instead of the transfer mold in which the recesses were regularly arranged at intervals of 5.0 μm, a transfer mold having recesses at positions corresponding to the positions and sizes of the bumps was used. An anisotropic conductive film was produced in the same manner (see FIGS. 22 to 25). Using the produced anisotropic conductive film, the connection structures according to (1) to (4) were evaluated in the same manner as in Example 1. Table 17 shows the results.

<Example 20>
Sieve 100 g of Sn-Bi solder particles (5N Plus, Type 7) with a particle size of 2.0 μm to 14.0 μm or less (d90 = 12 μm) with a high-precision electroformed sieve (trade name, AS ONE Corporation) with an opening size of 5 μm. and collected those that did not pass. Subsequently, the collected solder particles were sieved with a high-precision electroformed sieve (trade name, AS ONE Co., Ltd.) with an opening size of 7 μm, and the solder particles that passed through the sieve were collected. The average particle size of the collected solder particles was 5.7 μm.

Subsequently, a recess with an opening diameter of 10.0 μmφ, a bottom diameter of 8.0 μmφ, and a depth of 7 μm (the bottom diameter of 8.0 μmφ is located in the center of the opening diameter of 10.0 μmφ when viewed from above). Transfer molds provided at positions corresponding to the centers of the bumps of chips C1, C2 and C3 were prepared. A polyimide film (thickness: 100 μm) was used as the transfer type film. Solder particles having an average particle diameter of 5.7 μm were arranged in the recesses of the transfer mold.
Subsequently, after carrying out in the same manner as in (Step 3) of Example 1, in (Step 4) of Example 1, by changing the pressure to 0.1 MPa (1.0 kgf/cm ² ) and pressurizing, The adhesive component of the adhesive film was introduced into the recesses to fix a plurality of solder particles to the adhesive film (see FIG. 9(b)).
Subsequently, (Step 5) of Example 1 was carried out to obtain an anisotropic conductive film in which particle groups composed of a plurality of solder particles were arranged in layers (see FIG. 9C). The average number of solder particles forming the particle group was 3.5. In the same manner as in Example 1, the connection structures having the configurations according to (1) to (3) were evaluated. Table 18 shows the results.

<Example 21>
An anisotropic conductive film was produced using the solder particles having an average particle size of 4.6 μm obtained in Example 14 and using the same transfer mold as in Example 20. The average number of solder particles forming the particle group was 5.7. In the same manner as in Example 1, the connection structures having the configurations according to (1) to (3) were evaluated. Table 19 shows the results.

<Example 22>
An anisotropic conductive film was produced using the solder particles having an average particle size of 3.7 μm obtained in Example 15 and using the same transfer mold as in Example 20. The average number of solder particles forming the particle group was 9.5. In the same manner as in Example 1, the connection structures according to (1) to (3) were evaluated. Table 20 shows the results.

<Example 23>
Sieve 100 g of Sn-Bi solder particles (5N Plus, Type 6) with a particle size of 5.0 μm to 23.0 μm or less (d90 = 16 μm) with a high-precision electroformed sieve (trade name, AS ONE Corporation) with an opening size of 5 μm. and collected those that did not pass. Subsequently, the collected solder particles were sieved with a high-precision electroformed sieve (trade name, AS ONE Co., Ltd.) with an opening size of 7 μm, and the solder particles that passed through the sieve were collected. The average particle size of the collected solder particles was 6.7 μm.

Subsequently, a recess with an opening diameter of 10.0 μmφ, a bottom diameter of 8.0 μmφ, and a depth of 7 μm (the bottom diameter of 8.0 μmφ is located in the center of the opening diameter of 10.0 μmφ when viewed from above). Transfer molds provided at positions corresponding to the centers of the bumps of the chips C1 and C2 were prepared. A polyimide film (thickness: 100 μm) was used as the transfer type film. Solder particles having an average particle diameter of 6.7 μm were arranged in the recesses of the transfer mold.
Subsequently, after carrying out in the same manner as in (Step 3) of Example 1, in (Step 4) of Example 1, by changing the pressure to 0.1 MPa (1.0 kgf/cm ² ) and pressurizing, The adhesive component of the adhesive film was introduced into the recesses to fix a plurality of solder particles to the adhesive film (see FIG. 9(b)).
Subsequently, (Step 5) of Example 1 was carried out to obtain an anisotropic conductive film in which particle groups composed of a plurality of solder particles were arranged in layers (see FIG. 9C). The average number of solder particles forming the particle group was 4.2. In the same manner as in Example 1, the connection structures having the configurations according to (1) and (2) were evaluated. Table 21 shows the results.

<Example 24>
An anisotropic conductive film was produced using the solder particles having an average particle size of 4.6 μm obtained in Example 14 and using the same transfer mold as in Example 23. The average number of solder particles forming the particle group was 6.5. In the same manner as in Example 1, the connection structures having the configurations according to (1) and (2) were evaluated. Table 22 shows the results.

<Example 25>
An anisotropic conductive film was produced using the solder particles having an average particle size of 3.7 μm obtained in Example 15 and using the same transfer mold as in Example 23. The average number of solder particles forming the particle group was 9.3. In the same manner as in Example 1, the connection structures having the configurations according to (1) and (2) were evaluated. Table 23 shows the results.

<Comparative Example 1>

A solder particle-containing anisotropic conductive paste was prepared containing the following components in the following parts by mass.
(Polymer): 12 parts by mass (thermosetting compound): 29 parts by mass (high dielectric constant curing agent): 20 parts by mass (thermosetting agent): 11.5 parts by mass (flux): 2 parts by mass (solder particles) 34 parts by mass

(polymer)
Synthesis of reaction product (polymer A) of bisphenol F, 1,6-hexanediol diglycidyl ether, and bisphenol F type epoxy resin:
72 parts by mass of bisphenol F (containing 4,4'-methylenebisphenol, 2,4'-methylenebisphenol and 2,2'-methylenebisphenol in a mass ratio of 2:3:1), 1,6-hexanediol diol 70 parts by mass of glycidyl ether and 30 parts by mass of bisphenol F type epoxy resin (“EPICLON EXA-830CRP” manufactured by DIC Corporation) were placed in a three-necked flask and dissolved at 150° C. under nitrogen flow. Then, 0.1 parts by mass of tetra-n-butylsulfonium bromide, which is an addition reaction catalyst between hydroxyl groups and epoxy groups, is added, and the addition polymerization reaction is performed at 150° C. for 6 hours under nitrogen flow, whereby the reactant (polymer ).

(Thermosetting compound): resorcinol type epoxy compound, "EX-201" manufactured by Nagase ChemteX Co., Ltd.
(High dielectric constant curing agent): Pentaerythritol tetrakis (3-mercaptobutyrate)

(Heat curing agent): Showa Denko K.K. "Karens MT PE1"

(Flux): Adipic acid, manufactured by Wako Pure Chemical Industries, Ltd.

(solder particles):
200 g of SnBi solder particles (“ST-3” manufactured by Mitsui Kinzoku Mining Co., Ltd.), 40 g of adipic acid, and 70 g of acetone were weighed into a three-necked flask, and then the hydroxyl groups on the surface of the solder particles and the carboxyl of adipic acid 0.3 g of dibutyl tin oxide, which is a dehydration condensation catalyst with groups, was added and reacted at 60° C. for 4 hours. After that, the solder particles were collected by filtration. The collected solder particles, 50 g of adipic acid, 200 g of toluene, and 0.3 g of p-toluenesulfonic acid were weighed into a three-necked flask, and reacted at 120° C. for 3 hours while vacuuming and refluxing. . At this time, a Dean-Stark extraction apparatus was used to carry out the reaction while removing water produced by the dehydration condensation. After that, the solder particles were collected by filtration, washed with hexane, and dried. After that, the obtained solder particles were pulverized by a ball mill, and a sieve was selected so as to obtain a predetermined CV value. The obtained SnBi solder particles had an average particle size of 4 μm and a CV value of 7%.

A chip with copper bumps and a substrate with copper bumps were prepared in the same manner as in (Step 6) and (Step 7) of Example 1. A connection structure having the following structure was produced. An anisotropic conductive paste containing solder particles and a chip are formed on the substrate. The bumps of the chip with copper bumps and the bumps of the substrate with copper bumps were aligned. Heating and pressure were applied from above the chip under the conditions of 180° C., 4 gf/bump, and 30 seconds to form the final connection. A total of five types of connection structures according to (1) to (5) were produced by the following combinations of "chip/solder particle-containing anisotropic conductive paste/substrate" (1) to (5). The connection structure was evaluated in the same manner as in Example 1. Table 24 shows the results.
(1) chip C1/16 μm thick (on copper bumps) anisotropic conductive paste containing solder particles/substrate D1,
(2) chip C2/16 μm thick (on copper bumps) anisotropic conductive paste containing solder particles/substrate D2;
(3) chip C3/12 μm thick (on copper bumps) anisotropic conductive paste containing solder particles/substrate D3;
(4) chip C4/8 μm thick (on copper bumps) anisotropic conductive paste containing solder particles/substrate D4;
(5) chip C5/8 μm thick (on copper bumps) anisotropic conductive paste containing solder particles/substrate D5;

<Comparative Example 2>

Instead of 200 g of SnBi solder particles ("ST-3" manufactured by Mitsui Kinzoku Mining Co., Ltd.) used in Comparative Example 1, 200 g of SnBi solder particles ("ST-5" manufactured by Mitsui Kinzoku Mining Co., Ltd.) were used, and the average particle The connection structure was evaluated in the same manner as in Comparative Example 1, except that SnBi solder particles with a diameter of 6 μm and a CV value of 10% were used. Table 25 shows the results.

1 Solder particles 1A Particle group 2 Insulating film (adhesive component) 2a Film (adhesive component) 2b First film 2c Surface of first film 2d Second film (adhesive component) 10, 20... anisotropic conductive film 30... first circuit member 31... first substrate 32... first electrode 40... second circuit member 41... Second substrate 42 Second electrode 50A to 50F Connection structure 55 Insulating resin layer (adhesive component or cured product thereof) 60 Transfer mold 62 Concave (opening) 70 Solder layer, 71... Layer of intermetallic compound.

Claims (15)

A method for producing an anisotropic conductive film,
(a) accommodating one or more solder particles in a plurality of openings provided in a transfer mold;
(b) obtaining a first film to which the solder particles have been transferred by bringing an insulating adhesive component into contact with the side of the transfer mold on which the opening is provided;
(c) obtaining an anisotropic conductive film by forming a second film made of an insulating adhesive component on the surface of the first film to which the solder particles have been transferred; ,
In this order, a method for producing an anisotropic conductive film. 2. The manufacturing method according to claim 1, wherein the solder particles are exposed on the surface of the first film obtained in step (b). 2. The manufacturing method according to claim 1, wherein in the step (b), the solder particles are embedded in the surface side of the first film by allowing the adhesive component to penetrate into the interior of the opening. . The manufacturing method according to any one of claims 1 to 3, wherein step (b) comprises curing the adhesive component after transferring the solder particles. An anisotropic conductive film,
an insulating film made of an insulating adhesive component;
a plurality of solder particles arranged in the insulating film;
including
In the longitudinal section of the anisotropic conductive film, the particle group consisting of one solder particle or a plurality of the solder particles is arranged in the horizontal direction while being separated from the adjacent one solder particle or the particle group. An anisotropic conductive film placed. 6. The anisotropic conductive film according to claim 5, wherein the particle groups are arranged regularly in the cross section of the anisotropic conductive film. 7. The anisotropic conductive film according to claim 5, wherein said solder particles have an average particle size of 0.6 to 15 μm. An anisotropic conductive film according to any one of claims 5 to 7, wherein the solder particles comprise tin or a tin alloy. 9. Any one of claims 5 to 8, wherein the solder particles are made of In--Sn alloy, In--Sn--Ag alloy, Sn--Bi alloy, Sn--Bi--Ag alloy, Sn--Ag--Cu alloy or Sn--Cu alloy. or the anisotropic conductive film according to item 1. The anisotropic conductive film according to any one of claims 5 to 9, wherein surfaces of said solder particles are coated with a flux component. providing a first circuit member having a first substrate and a first electrode on the first substrate;
providing a second circuit member having a second electrode electrically connected to the first electrode;
Between the surface having the first electrode of the first circuit member and the surface having the second electrode of the second circuit member, according to any one of claims 5 to 10 disposing an anisotropic conductive film;
By heating the laminate including the first circuit member, the anisotropic conductive film, and the second circuit member to the melting point of the solder particles or higher while pressing the laminate in the thickness direction of the laminate. electrically connecting the first electrode and the second electrode via solder and adhering the first circuit member and the second circuit member;
A method of manufacturing a connection structure comprising: a first circuit member having a first substrate and a first electrode provided on the first substrate;
a second circuit member having a second electrode electrically connected to the first electrode;
a solder joint interposed between the first electrode and the second electrode;
an insulating resin layer provided between the first circuit member and the second circuit member and bonded to the first circuit member and the second circuit member;
A connection structure with At least one of the first electrode and the second electrode is made of a material selected from the group consisting of copper, nickel, palladium, gold, silver and alloys thereof, and indium tin oxide. Described connection structure. At least one of the first electrode and the second electrode is made of copper,
The connection structure according to claim 12 or 13, wherein said first electrode and said second electrode are connected via a layer made of an intermetallic compound. 15. The connection structure according to claim 14, wherein the layer made of the intermetallic compound has a thickness of 0.1 to 10.0 μm.

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