JP2022074048A - Conductive adhesive, anisotropic conductive film, connection structure, and manufacturing method for connection structure - Google Patents

Abstract

To provide a conductive adhesive that is able to satisfactory solder wettability and conductivity and to provide an anisotropic conductive film, a connection structure, and a method of manufacturing the connection structure, which can obtain satisfactory solder wettability, conductivity, and insulating property.SOLUTION: An anisotropic conductive film contains a thermosetting binder, solder particles, and a dicarboxylic acid. The solder particles contain 50 to 80 wt.% of Sn and 20 to 50 wt.% of Bi; an amount of blended dicarboxylic acid is 1 to 15 pts.mass per 100 pts.mass of the thermosetting binder; an amount of blended solder particles with respect to an average particle diameter of 40 to 5 μm of the solder particles is 100 to 1200 pts.mass per 100 pts.mass of the thermosetting binder; and a thickness of the anisotropic conductive film is more than 110% to 700% or less of the average particle diameter of the solder particles. As a result, satisfactory solder wettability, conductivity, and insulating property can be obtained.SELECTED DRAWING: Figure 1

Description

The present art relates to a conductive adhesive for connecting a first electronic component and a second electronic component, an anisotropic conductive film, a connection structure, and a method for manufacturing the connection structure.

In recent years, as information devices such as mobile phones and PCs (Personal Computers) have become more multifunctional or smaller and lighter, the density of electronic components mounted on a substrate has been increasing. Therefore, the electrodes of electronic components are narrowed in pitch, and improvement of high-density mounting technology for joining the electrodes of the substrate and the electrodes of electronic components is required.

The mounting of the electronic component is performed, for example, through the following steps (1) to (5) (see, for example, Patent Document 1).
(1) A process of applying solder paste on the electrodes of a substrate by screen printing using a solder mask.
(2) The process of arranging electronic components on the solder paste.
(3) A process in which a substrate on which electronic components are arranged is passed through a reflow furnace, and the electrodes of the substrate and the electrodes of electronic components are electrically bonded by soldering.
(4) A process of injecting underfill into the gap between the substrate and electronic components for the purpose of protecting and reinforcing the soldered portion.
(5) A step of sealing and joining with a resin by curing the underfill resin.

However, such a conventional method for mounting electronic components has a problem that the number of steps after soldering is large.

Patent Document 2 proposes a method having the following steps (1) to (3) as a method for mounting an electronic component capable of performing electrical bonding with solder, sealing with resin, and bonding at once. ..
(1) A bonding material layer having a thermosetting resin layer containing a solder powder containing a thermosetting resin, solder powder and a reducing agent and a thermoplastic resin layer containing a thermoplastic resin is placed on the surface of the substrate on the electrode side. The process of setting.
(2) A process of arranging electronic components on the bonding material layer.
(3) By melting the bonding material layer, solder powder is collected and fused between the electrodes of the substrate and the electrodes of the electronic components, and the electrodes are electrically bonded at the solder bonding portion, and at the same time, solder bonding is performed. A step of curing a hybrid resin containing a thermosetting resin and a thermoplastic resin that has flowed around the part, and sealing and joining with the resin joint part.

Such a mounting method can be applied to multi-electrode electronic components such as BGA (Ball Grid Array) and LGA (Land Grid Array), and the process can be simplified. However, in the case of the mounting method described in Patent Document 2, since the bonding material needs to have a structure in which a liquid thermosetting resin is sandwiched between two thermoplastic resin layers, the bonding material is in the form of a film or a reel. There is a problem that it is difficult to form a shape.

Patent Document 3 describes conductivity on an electrode by a conductive material containing a plurality of conductive particles having solder on the outer surface portion of the conductive portion, a thermosetting compound, an acid anhydride thermosetting agent, and an organic phosphorus compound. A mounting method that can efficiently arrange the solder in the sex particles has been proposed.

However, since the conductive material of Patent Document 3 is in the form of a paste, it is necessary to arrange the conductive material on the electrodes by screen printing or the like, and it is difficult to control the coating amount and improve the position accuracy, and further, it is difficult to improve the position accuracy between the electrodes. Since solder agglomerates are likely to occur, short circuits are likely to occur, and there is a problem that it is difficult to achieve both insulation and conductivity.

Patent Document 4 describes a film-like anisotropic bonding material containing at least one solid resin selected from a thermoplastic resin, a solid radical polymerizable resin, and a solid epoxy resin, solder particles, and a flux compound. A mounting method has been proposed in which an electrode of a first electronic component and an electrode of a second electronic component are heat-bonded with no load.

However, although the method described in Patent Document 4 can be applied to an LED (Light Emitting Diode) chip or the like having a small number of electrodes, the solder particles hardly move onto the electrodes and the number of electrodes of connector parts or the like is small. There is a problem that stable connection is difficult with many electronic components.

Japanese Unexamined Patent Publication No. 2001-239395 Japanese Unexamined Patent Publication No. 2016-143741 International Publication No. 2018/0663668 Japanese Unexamined Patent Publication No. 2020-07870

With conventional conductive materials containing solder particles, it is difficult to efficiently move the solder particles onto the electrodes at the time of connection, and it is difficult to arrange the solder particles between the upper and lower electrodes to be connected. For example, in the case of a paste-like conductive material, the aggregation rate of solder particles at the time of connection is often too fast, huge aggregates of solder particles are generated on the electrodes, bridges are formed between adjacent electrodes, and they are adjacent to each other. Insulation between electrodes may be reduced. Further, for example, in the case of a film-shaped conductive material, the aggregation speed of the solder particles at the time of connection is often too slow, the solder particles are not arranged on the electrodes, and the conductivity between the upper and lower electrodes may decrease. rice field.

This technique has been proposed in view of such conventional circumstances, and provides a conductive adhesive capable of obtaining good solder wettability and conductivity. Further, the present invention provides an anisotropic conductive film, a connection structure, and a method for manufacturing the connection structure, which can obtain good solder wettability, conductivity, and insulation.

As a result of diligent studies, the present inventor has found that the above-mentioned object can be achieved by using solder particles having a predetermined component and a dicarboxylic acid, and has completed the present invention.

That is, the conductive adhesive according to the present technology contains a thermosetting binder, solder particles, and dicarboxylic acid, and the solder particles contain 50 to 80 wt% Sn and 20 to 50 wt% Bi. Including, the blending amount of the solder particles is 100 parts by mass or more with respect to 100 parts by mass of the thermosetting binder.

Further, the anisotropic conductive film according to the present technology contains a thermosetting binder, solder particles, and a dicarboxylic acid, and the solder particles contain 50 to 80 wt% Sn and 20 to 50 wt% Bi. The blending amount of the solder particles with respect to the average particle size of the solder particles of 40 to 5 μm is 100 to 1200 parts by mass with respect to 100 parts by mass of the thermosetting binder, and the thickness of the anisotropic conductive film is , 110% or more and 700% or less of the average particle size of the solder particles.

The connection structure according to the present technology is interposed between the first electronic component, the second electronic component, the electrode of the first electronic component, and the electrode of the second electronic component, and has the conductivity. It is provided with an adhesive or a cured film obtained by curing the anisotropic conductive film, and the solder area of the solder particles is 50% or more with respect to the electrode area of the first electronic component or the electrode area of the second electronic component. ..

In the method for manufacturing a connection structure according to the present technology, the conductive adhesive or the anisotropic conductive film is interposed between the electrodes of the first electronic component and the electrodes of the second electronic component, and the above is described. The electrodes of the first electronic component and the electrodes of the second electronic component are joined to each other using a reflow furnace with no load.

According to this technique, good solder wettability and conductivity can be obtained by containing solder particles having a predetermined component and a dicarboxylic acid. In addition, good solder wettability, conductivity, and insulation can be obtained.

FIG. 1 is a cross-sectional view schematically showing a part of an anisotropic conductive film to which the present technique is applied. FIG. 2 is a cross-sectional view schematically showing an example of the first electronic component. FIG. 3 is a cross-sectional view schematically showing a state in which an anisotropic conductive film is provided on the terminals of the first electronic component. FIG. 4 is a cross-sectional view schematically showing the alignment of the terminal row of the first electronic component and the terminal row of the second electronic component. FIG. 5 is a cross-sectional view schematically showing a state in which the second electronic component is placed on the first electronic component. FIG. 6 is a cross-sectional view schematically showing a state in which the first electronic component and the second electronic component are heated in a reflow oven. FIG. 7 is a graph showing an example of a temperature profile for reflow oven processing. FIG. 8 is a graph showing the measurement result of the melt viscosity of the anisotropic conductive film of Example 2 and the measurement result of DSC. FIG. 9 is a photomicrograph of the terminals of the printed wiring board after the reflow oven treatment of Example 2. FIG. 10 is a photomicrograph of the terminals of the printed wiring board after the reflow oven treatment of Example 3. FIG. 11 is a photomicrograph of the terminals of the printed wiring board after the reflow oven treatment of Comparative Example 1. FIG. 12 is a photomicrograph of the terminals of the printed wiring board after the reflow oven treatment of Comparative Example 2. FIG. 13 is a photomicrograph of the terminals of the printed wiring board after the reflow oven treatment of Comparative Example 7.

Hereinafter, embodiments of the present technology will be described in detail in the following order with reference to the drawings.
1. 1. Conductive adhesive and anisotropic conductive film 2. Connection structure 3. Manufacturing method of connection structure 4. Example

<1. Conductive adhesives and anisotropic conductive films>
The conductive adhesive according to the present technique contains a thermosetting binder, solder particles, and a dicarboxylic acid, and the solder particles contain 50 to 80 wt% Sn and 20 to 50 wt% Bi. The conductive adhesive may have isotropic properties that conduct in all directions, or may have anisotropy that conducts in the compressed direction between the counter electrodes. Further, the conductive adhesive may be in the form of a film or a paste. Further, the paste may be in the form of a film at the time of connection, or may be in a form similar to a film by mounting a component. In the case of a paste, a predetermined amount may be uniformly applied onto the substrate, and for example, application methods such as dispensing, stamping, and screen printing can be used, and the paste may be dried if necessary. In the case of a film, not only can the amount of the conductive adhesive be made uniform depending on the film thickness, but also the work efficiency can be improved because it is easy to handle.

The blending amount of the solder particles is 100 parts by mass or more, more preferably 150 parts by mass or more, and further preferably 175 parts by mass or more with respect to 100 parts by mass of the thermosetting binder. Thereby, good continuity can be obtained. When imparting anisotropy to the conductive adhesive, the upper limit of the blending amount of the solder particles is preferably 1200 parts by mass or less, more preferably 900 parts by mass or less with respect to 100 parts by mass of the thermosetting binder. .. If the amount of the solder particles is too large, huge agglomerates are likely to be generated, which tends to cause a short circuit between adjacent terminals.

The minimum melt viscosity of the conductive adhesive is 300 Pa · s or less, preferably 1 to 250 Pa · s or less, more preferably 1 to 200 Pa · s or less, and further preferably 1 to 150 Pa · s or less. If the minimum melt viscosity is too high, the resin will not melt under no load in reflow, which may hinder the sandwiching between the solder particles and the terminals. The lower limit of the minimum melt viscosity reaching temperature of the conductive adhesive is preferably 120 ° C. or higher, more preferably 130 ° C. or higher, still more preferably 140 ° C. or higher, and is the minimum melt viscosity reaching temperature of the anisotropic conductive film. The upper limit is preferably 200 ° C. or lower, more preferably 190 ° C. or lower, still more preferably 180 ° C. or lower. As a result, a good solder joint state can be obtained by the conventional reflow oven treatment under normal profile conditions. Here, the temperature at which the minimum melt viscosity of the conductive adhesive is reached is, for example, a leometer MARS3 (manufactured by HAAKE) equipped with an 8 mm diameter sensor and a plate, a gap of 0.2 mm, a temperature rise rate of 10 ° C./min, and a frequency of 1 Hz. , The temperature at which the melt viscosity is measured under the condition of the measurement temperature range of 20 to 250 ° C. and the viscosity becomes the lowest value (minimum melt viscosity).

On the surface of the solder particles, an oxide film (usually tin oxide in the case of solder containing tin (Sn)) is present with a thickness of several nm. Therefore, in the state as it is, the solder particles cannot be aggregated even if the solder is heated to a temperature higher than the melting point of the solder, and the continuity of the upper and lower electrodes cannot be obtained by the no-load reflow process.

In order to agglomerate the solder particles, it is necessary to reduce the oxide film on the surface of the particles and reduce the amount of the oxide film. It has been found that good solder agglomeration can be generated in the no-load reflow treatment by combining the solder particles containing the above-mentioned solder particles and the dicarboxylic acid represented by the following formula (1).

Further, it is known that the carboxylic acid (nR-COOH) reduces the metal oxide (MO) by the reduction reaction represented by the following formula (2).

The solder particles whose surface oxide film has decreased due to the reduction reaction are between the electrodes due to the collision between the solder particles and the contact of the solder particles with the metal on the electrode surface due to the marangoni effect and the thermal flow of the binder. It is possible to obtain a good connection. The solder particles containing 50 to 80 wt% Sn and 20 to 50 wt% Bi have an appropriate amount of tin oxide on the surface, and the solder particles move due to the reaction between the tin oxide on the surface and the carboxylic acid. It is presumed that the driving force to be obtained is easy to obtain.

FIG. 1 is a cross-sectional view schematically showing a part of an anisotropic conductive film to which the present technique is applied. As shown in FIG. 1, the anisotropic conductive film 10 is formed by dispersing solder particles 11 in a thermosetting binder. Further, the anisotropic conductive film 10 may have the first film attached to the first surface and the second film attached to the second surface, if necessary.

The thickness of the anisotropic conductive film 10 is more than 110% and 700% or less of the average particle size of the solder particles 11, preferably more than 110% and 500% or less of the average particle size of the solder particles 11, and more preferably the solder particles 11. It is more than 110% and 400% or less of the average particle size of the solder. Further, the thickness of the anisotropic conductive film 10 is preferably 5 μm or more larger than the average particle size of the solder particles. If the thickness of the anisotropic conductive film 10 is too thin with respect to the average particle size of the solder particles 11, aggregation (movement) of the solder particles is unlikely to occur, and if it is too thick, the absolute amount of solder increases, resulting in a short circuit between adjacent terminals. It tends to be caused easily, and insufficient removal of the resin tends to occur.

In the present specification, the film thickness can be measured using a known micrometer or a digital thickness gauge (for example, Mitutoyo Co., Ltd .: MDE-25M, minimum display amount 0.0001 mm). The film thickness may be obtained by measuring, for example, 10 or more points and averaging them. Further, the average particle size is N = 50 or more, preferably N = 100 or more, more preferably N = 200 or more in an observation image using an electron microscope such as a metallurgical microscope, an optical microscope, or an SEM (Scanning Electron Microscope). It is the average value of the major axis diameters of the particles measured in 1. When the particles are spherical, it is the average value of the diameters of the particles. In addition, the measured values and image-type grain size distribution of the observed images measured using known image analysis software (“WinROOF”: Mitani Shoji Co., Ltd., “A Image-kun (registered trademark)”: Asahi Kasei Engineering Co., Ltd., etc.) It may be a measured value (N = 1000 or more) measured using a measuring device (for example, FPIA-3000 (Malburn)). The average particle size obtained from the observation image or the image-type particle size distribution measuring device can be the average value of the maximum lengths of the particles. When producing an anisotropic bonded material, the particle size (D50) and the arithmetic mean diameter (volume standard) at which the cumulative frequency in the particle size distribution simply obtained by the laser diffraction / scattering method is 50%. It is preferable) and other manufacturer values can be used.

Similar to the above-mentioned conductive adhesive, the minimum melt viscosity of the anisotropic conductive film is 300 Pa · s or less, preferably 1 to 250 Pa · s or less, more preferably 1 to 200 Pa · s or less, still more preferably 1. It is ~ 150 Pa · s or less. If the minimum melt viscosity is too high, the resin will not melt under no load in reflow, which may hinder the sandwiching between the solder particles and the terminals. The lower limit of the temperature at which the minimum melt viscosity of the anisotropic conductive film is reached is preferably 120 ° C. or higher, more preferably 130 ° C. or higher, still more preferably 140 ° C. or higher, and the minimum melt viscosity reached temperature of the anisotropic conductive film. The upper limit of the temperature is preferably 200 ° C. or lower, more preferably 190 ° C. or lower, still more preferably 180 ° C. or lower. As a result, a good solder joint state can be obtained by the conventional reflow oven treatment under normal profile conditions. Here, the temperature at which the minimum melt viscosity of the anisotropic conductive film is reached is, for example, a leometer MARS3 (manufactured by HAAKE) equipped with an 8 mm diameter sensor and a plate, a gap of 0.2 mm, a temperature rise rate of 10 ° C./min, and a frequency. The melt viscosity is measured under the conditions of 1 Hz and the measurement temperature range of 20 to 250 ° C., and the temperature at which the viscosity becomes the lowest value (minimum melt viscosity).

Further, it is preferable that the melt viscosity of the anisotropic conductive film is 300 Pa · s or less at the temperature of the endothermic peak measured by DSC (differential scanning calorimetry) of the solder particles. As a result, solder agglomeration is likely to occur due to collision between the solder particles or contact of the solder particles with the metal on the electrode surface, and a good solder bonding state can be obtained.

[Thermosetting binder]
The thermosetting binder is not particularly limited as long as it exhibits insulating properties. For example, a thermal anion polymerization type resin composition containing an epoxy compound and a thermal anion polymerization initiator, an epoxy compound and a thermal cationic polymerization Examples thereof include a thermal cationic polymerization type resin composition containing an initiator, a thermal radical polymerization type resin composition containing a (meth) acrylate compound and a thermal radical polymerization initiator, and the like. The (meth) acrylate compound means to include both an acrylic monomer (oligomer) and a methacrylic monomer (oligomer).

Hereinafter, as a specific example, a thermal anionic polymerization type resin composition containing a film-forming resin, a solid epoxy resin, a liquid epoxy resin, and an epoxy resin curing agent will be described as an example.

The film-forming resin corresponds to, for example, a high molecular weight resin having an average molecular weight of 10,000 or more, and is preferably having an average molecular weight of about 10,000 to 80,000 from the viewpoint of film formability. Examples of the film-forming resin include various resins such as phenoxy resin, polyester resin, polyurethane resin, polyester urethane resin, acrylic resin, polyimide resin and butyral resin, which may be used alone or in combination of two or more. May be used. Among these, it is preferable to use a phenoxy resin from the viewpoint of film formation state, connection reliability and the like. The blending amount of the film-forming resin is preferably 20 to 50 parts by mass, more preferably 25 to 45 parts by mass or less, based on 100 parts by mass of the total of the film-forming resin, the solid epoxy resin, the liquid epoxy resin, and the epoxy resin curing agent. , More preferably 30 to 40 parts by mass.

The solid epoxy resin is not particularly limited as long as it is an epoxy resin that is solid at room temperature and has one or more epoxy groups in the molecule, and is, for example, a bisphenol A type epoxy resin, a biphenyl type epoxy resin, or the like. There may be. Among these, it is preferable to use a crystalline bisphenol A type epoxy resin having a low melt viscosity. As a specific example of the crystalline bisphenol A type epoxy resin available on the market, the trade name "YL6810" (crystalline BPA type epoxy resin) of Mitsubishi Chemical Co., Ltd., which has a viscosity of 40 to 55P by the Gardner-Holt method. And so on. The blending amount of the solid epoxy resin is preferably 30 to 60 parts by mass, more preferably 35 to 55 parts by mass or less, based on 100 parts by mass of the total of the film-forming resin, the solid epoxy resin, the liquid epoxy resin, and the epoxy resin curing agent. , More preferably 40 to 50 parts by mass. The normal temperature is in the range of 20 ° C. ± 15 ° C. (5 ° C. to 35 ° C.) defined by JIS Z 8703.

The liquid epoxy resin is not particularly limited as long as it is liquid at room temperature, and may be, for example, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, or a urethane-modified epoxy resin. not. Among these, it is preferable to use a high-purity hydrogenated epoxy resin. Specific examples of the high-purity hydrogenated epoxy resin available on the market include the trade name "YX8000" (hydrogenated BPA type epoxy resin) of Mitsubishi Chemical Corporation. The blending amount of the liquid epoxy resin is preferably 1 to 25 parts by mass, more preferably 1 to 20 parts by mass or less, based on 100 parts by mass of the total of the film-forming resin, the solid epoxy resin, the liquid epoxy resin, and the epoxy resin curing agent. , More preferably 5 to 15 parts by mass.

The epoxy resin curing agent is not particularly limited as long as it is a thermosetting agent that starts curing by heat, and examples thereof include anionic curing agents such as imidazole, dicyandiamide, and isophthalic acid dihydrazide. Further, the epoxy resin curing agent may be microencapsulated. The blending amount of the epoxy resin curing agent is preferably 1 to 25 parts by mass, more preferably 1 to 20 parts by mass, based on 100 parts by mass of the total of the film-forming resin, the solid epoxy resin, the liquid epoxy resin, and the epoxy resin curing agent. Hereinafter, it is more preferably 5 to 15 parts by mass.

As other additives to be added to the thermosetting binder, if necessary, a silane coupling agent, acrylic rubber, a diluting monomer such as various acrylic monomers, a filler, a softener, a colorant, and a flame retardant agent. , Tixotropic agents and the like may be blended.
[Solder particles]

The solder particles contain 50-80 wt% Sn and 20-50 wt% Bi, more preferably 45-75 wt% Sn and 25-55 wt% Bi. As a result, a good solder joint state can be obtained by the conventional reflow oven treatment under normal profile conditions. Further, the solder particles may contain other metals such as Cu and Ag of 1 Wt% or less from the viewpoint of improving the solder strength, for example.

Specific examples of the solder particles include Sn-50Bi, Sn-40Bi-0.1Cu, Sn-30Bi-0.5Cu, Sn-20Bi and the like. Among these, it is preferable to use 59.9Sn-40Bi-0.1Cu or 69.5Sn-30Bi-0.5Cu, which are particularly excellent in solder wettability.

The lower limit of the blending amount of the solder particles is preferably 100 parts by mass or more, more preferably 150 parts by mass or more, still more preferably 175 parts by mass or more with respect to 100 parts by mass of the thermosetting binder, and the blending amount of the solder particles. The upper limit is 1200 parts by mass or less, more preferably 900 parts by mass or less, and 300 parts by mass or less may be preferable with respect to 100 parts by mass of the thermosetting binder. If the amount of solder particles is too large, huge agglomerates are likely to occur, which tends to cause a short circuit between adjacent terminals. If the amount of solder particles is too small, good agglomeration of solder particles tends not to occur. There is.

The lower limit of the average particle size of the solder particles is preferably 5 μm or more, more preferably 10 μm or more, still more preferably 15 μm or more, and the upper limit of the average particle size of the solder particles is preferably 50 μm or less, more preferably 40 μm or less. More preferably, it is 35 μm or less, and a preferable range is 10 to 40 μm. If the average particle size of the solder particles is too small, excessive aggregation of the solder particles in a state where the solder particles are not bonded to each other during the no-load reflow process tends to occur, which tends to cause a short circuit between adjacent terminals. If the average particle size of the particles is too large, the movement of the solder particles becomes poor, and it becomes difficult to generate good aggregation of the solder particles.

The blending amount of the solder particles with respect to the average particle size of the solder particles of 30 to 10 μm is preferably 100 to 1200 parts by mass with respect to 100 parts by mass of the thermosetting binder. Further, the blending amount of the solder particles with respect to the average particle size of the solder particles of 30 to 20 μm is preferably 100 to 900 parts by mass with respect to 100 parts by mass of the thermosetting binder. The blending amount of the solder particles with respect to the average particle size of the solder particles of 20 to 10 μm is preferably 100 to 1200 parts by mass with respect to 100 parts by mass of the thermosetting binder. By blending the solder particles according to the average particle size of the solder particles, good solder wettability, conductivity, and insulation can be obtained.
[Dicarboxylic acid]

The dicarboxylic acid is not particularly limited as long as the oxide film on the surface of the solder particles can be reduced by a reduction reaction, but the dicarboxylic acid may be a compound (n = 1 to 8) represented by the following formula (1). preferable.

That is, as the dicarboxylic acid, malonic acid (n = 1, carbon number 3), succinic acid (n = 2, carbon number 4), glutaric acid (n = 3, carbon number 5), adipic acid (n = 4, carbon number 4). Number 6), pimelic acid (n = 5, carbon number 7), suberic acid (n = 6, carbon number 8), azelaic acid (n = 7, carbon number 9), sebacic acid (n = 8, carbon number 10) ) Is preferably used. Among these, it is preferable to use malonic acid, succinic acid, or glutaric acid, which have particularly excellent solder wettability. Further, the dicarboxylic acid can use not only a straight chain but also a branched, saturated or unsaturated structure. In addition to the dicarboxylic acid, a rosin-based carboxylic acid can also be used, and the dicarboxylic acid and the rosin-based carboxylic acid may be used in combination. That is, a rosin-based carboxylic acid may be contained instead of the dicarboxylic acid, or a rosin-based carboxylic acid may be further contained.

The amount of the dicarboxylic acid to be blended is preferably 1 to 15 parts by mass, more preferably 2 to 12 parts by mass, still more preferably 4 to 10 parts by mass, still more preferably 6 to 10 parts by mass with respect to 100 parts by mass of the thermosetting binder. It is a mass part. If the amount of the dicarboxylic acid is too small, the oxide film on the surface of the solder particles cannot be sufficiently reduced and it becomes difficult to generate solder aggregation. If the amount of the dicarboxylic acid is too large, the insulating property deteriorates. It is easy to cause a short circuit.

In the above-mentioned anisotropic conductive film, for example, a thermosetting binder, solder particles, and a dicarboxylic acid are mixed in a solvent, and this mixture is applied to a release-treated film by a bar coater so as to have a predetermined thickness. It can then be obtained by drying and volatilizing the solvent. Further, the mixture may be applied onto the peeling film by a bar coater and then pressed to a predetermined thickness. Further, in order to increase the dispersibility of the solder particles, it is preferable to apply a high share in a state containing a solvent. For example, a known batch type planetary agitator can be used. It may be something that can be done in a vacuum environment.

<2. Connection structure>
The connection structure according to the present technology is interposed between the first electronic component, the second electronic component, the electrode of the first electronic component, and the electrode of the second electronic component, and has the above-mentioned anisotropy. A cured film obtained by curing the conductive film is provided, and the solder area of the solder particles is 50% or more with respect to the electrode area of the first electronic component or the electrode area of the second electronic component. Thereby, excellent conductivity and insulation can be obtained.

Further, the solder area of the solder particles with respect to the electrode area of the first electronic component or the electrode area of the second electronic component is preferably 70% or more. As a result, the solder is sufficiently wetted and spread on the electrodes, and further excellent conductivity and insulating properties can be obtained. The solder area on the electrode can be calculated by observing the molten state of the solder on the electrode of the electronic component after the reflow treatment with a metal microscope and measuring the solder area with respect to the electrode area.

The first electronic component and the second electronic component are not particularly limited and may be appropriately selected depending on the intended purpose. For example, glass substrates such as printed wiring boards (PWB), plastic substrates, LCD (Liquid Crystal Display) panel applications, organic EL display (OLED) panel applications, plasma display panel (PDP) applications, crystalline silicon solar cells (single crystals). Silicon, polycrystal silicon, multi-junction solar cell, hetero-junction solar cell, HIT solar cell, perovskite tandem solar cell), thin-film solar cell (amorphous silicon system, microcrystalline silicon system, CIGS system, III-V group multi-junction system, GaAs-based, CdTe, perovskite-based, organic thin-film-based, dye-sensitized), quantum dot solar cells and the like can be mentioned. The second electronic component includes, for example, a general-purpose connector, an IC (Integrated Circuit), a flexible printed circuit board (FPC), a tape carrier package (TCP) board, a tab wire for collecting solar cells, and the like. Can be mentioned. In addition, this technology includes, for example, semiconductor devices (including all devices that use semiconductors such as optical elements, thermoelectric conversion elements, and photoelectric conversion elements in addition to driver ICs), display devices (monitors, televisions, head mount displays, etc.), Portable devices (tablet terminals, smartphones, wearable terminals, etc.), game machines, audio devices, image pickup devices (those that use image sensors such as camera modules), electrical equipment mounting for vehicles (mobile devices), medical devices, sensor devices (touch sensors) , Fingerprint authentication, iris authentication, etc.), and can be applied to all electronic devices that use electrical connections such as indoor and outdoor solar cells.

<3. Manufacturing method of connection structure>
In the method for manufacturing a connection structure according to the present technology, the above-mentioned anisotropic conductive film is interposed between the electrodes of the first electronic component and the electrodes of the second electronic component, and the electrodes of the first electronic component are interposed. And the electrode of the second electronic component are joined with no load using a reflow furnace. Thereby, good solder wettability, conductivity, and insulation can be obtained.

Hereinafter, with reference to FIGS. 2 to 6, the step (A) of providing the anisotropic conductive film on the first terminal row of the first electronic component, the second electronic component on the anisotropic conductive film. (B) and a step (C) of joining the first terminal row of the first electronic component and the second terminal row of the second electronic component using a reflow furnace will be described. do.

[Step (A)]
FIG. 2 is a cross-sectional view schematically showing an example of the first electronic component, and FIG. 3 is a cross-sectional view schematically showing a state in which an anisotropic conductive film is provided on the terminals of the first electronic component. It is a figure. As shown in FIGS. 2 and 3, in the step (A), the anisotropic conductive film 30 containing the solder particles 31 is provided on the first terminal row 21 of the first electronic component 20.

The step (A) may be a temporary sticking step of sticking the anisotropic conductive film 30 on the substrate at a low temperature, or may be a laminating step of laminating the anisotropic conductive film 30 on the substrate. ..

When the step (A) is a temporary pasting step, the anisotropic conductive film 30 can be provided on the substrate under known usage conditions. In this case, only the minimum changes such as the installation and change of tools from the conventional device are required, which is economically advantageous.

When the step (A) is a laminating step, for example, the anisotropic conductive film 30 is laminated on the first terminal row 21 of the first electronic component 20 by using a pressure type laminator. The laminating step may be a vacuum pressurization type. In the case of temporary pasting, the width of the film is restricted by the tool width, but in the case of the laminating process, since the heating and pressurizing tool is not used, it can be expected that a relatively wide width can be mounted all at once.

[Step (B)]
FIG. 4 is a cross-sectional view schematically showing the alignment of the terminal row of the first electronic component and the terminal row of the second electronic component. As shown in FIG. 4, in the step (B), for example, the tool 50 is used to align the first terminal row 21 of the first electronic component 20 and the terminal row 41 of the second electronic component 40. , The second electronic component 40 is placed on the anisotropic conductive film 30. The tool 50 preferably includes a suction mechanism for sucking the second electronic component 40.

[Step (C)]
FIG. 5 is a cross-sectional view schematically showing a state in which the second electronic component is placed on the first electronic component, and FIG. 6 shows the first electronic component and the second electronic component in a reflow furnace. It is sectional drawing which shows the heated state schematically. As shown in FIGS. 5 and 6, in step (C), the first terminal row 21 of the first electronic component 20 and the second electronic component 40 are used in a reflow furnace set to a predetermined profile. It is joined to the second terminal row 41.

Since the reflow furnace can be heat-bonded without a load without mechanical pressurization, damage to the first electronic component 20 and the second electronic component 40 can be suppressed. As the reflow furnace, atmospheric pressure reflow is preferable from the viewpoint of simplicity, but atmospheric pressure reflow, vacuum reflow, atmospheric pressure oven, autoclave (pressurized oven) and the like may be used.

In the reflow furnace, the heat-curing binder is melted by heating, the solder particles 31 are sandwiched between the electrodes by the weight of the first electronic component 40, the solder particles 31 are melted by the main heating which is equal to or higher than the solder melting point, and the solder is the electrode. By cooling, the first terminal row 21 of the first electronic component 20 and the second terminal example 41 of the second electronic component 40 are joined by the solder 32.

FIG. 7 is a graph showing an example of a temperature profile for reflow oven processing. The reflow process may include a temperature raising step, a keeping step of maintaining a constant temperature, and a temperature lowering step. It may also include a peak step at the highest temperature. The temperature raising step consists of two steps: a step of melting the thermosetting binder and sandwiching the solder particles between the terminals (for example, 0 to 170 ° C.) and a step of curing the thermosetting binder (for example, 170 to 250 ° C.). It may be. The heating rate may be, for example, 10 to 120 ° C./min or 20 to 100 ° C./min.

The keeping step may include a step of wetting and spreading the solder (for example, 170 ° C.) and a step of curing the thermosetting binder (for example, 250 ° C.). The keep temperature of the step of wetting and spreading the solder is, for example, 150 to 200 ° C., and the keep temperature of the step of curing the thermosetting binder is, for example, 200 to 250 ° C. The lower limit of the maintenance time of the keep step is 10 sec or more, preferably 30 sec or more, and the upper limit of the maintenance time of the keep step is 200 sec or less, preferably 150 sec or less. In the temperature lowering step, the solder particles are made into a solid phase by cooling to a temperature equal to or lower than the melting point of the solder particles, and the solder particles are bonded between the electrodes. The rate of temperature decrease should be high in order to increase productivity, and low when quenching is not desirable.

<4. Example>
In this example, solder particles having various compositions were prepared to prepare an anisotropic conductive film. Then, a connection structure was produced using an anisotropic conductive film, and the solder joint state, conduction resistance value, and insulation resistance value were evaluated. The present embodiment is not limited to these.

[Preparation of solder particles]
The metal material was placed in a container being heated at a predetermined compounding ratio, melted and then cooled to obtain a solder alloy. A powder was prepared from the solder alloy by an atomizing method and classified so as to have a predetermined particle size range to obtain solder particles.

Table 1 shows the melting characteristics of the solder particles used in Examples and Comparative Examples.

[Manufacturing anisotropic conductive film]
The following materials were prepared.
YP-50 (Nittetsu Chemical & Materials Co., Ltd., phenoxy resin) → Solution with solid content / MEK = 40/60 YL6810 (Mitsubishi Chemical Corporation, crystalline BPA type epoxy)
YX8000 (Made by Mitsubishi Chemical Corporation, hydrogenated BPA type epoxy)
2P4MHZ-PW (manufactured by Shikoku Chemicals Corporation, 2-phenyl-4-methyl-5-hydroxymethylimidazole)
Dicy7 (manufactured by Mitsubishi Chemical Corporation, dicyandiamide)
IDH-S (Otsuka Chemical Co., Ltd., isophthalic acid dihydrazide)

As shown in Tables 2 to 4, these materials were mixed and stirred in a predetermined formulation to obtain a mixed varnish. Subsequently, solder particles were added to the obtained mixed varnish in a predetermined amount with respect to the solid content of the mixed varnish to obtain an anisotropic conductive composition. The obtained anisotropic conductive composition was applied onto a PET film having a thickness of 50 μm to a predetermined thickness after drying, and dried at 80 ° C. for 5 minutes to prepare an anisotropic conductive film.

[Measurement of minimum melt viscosity and minimum melt viscosity reached temperature]
An 8 mm diameter sensor and a plate were attached to a leometer MARS3 (manufactured by HAAKE), and an anisotropic conductive film was set. Then, the melt viscosity was measured under the conditions of a gap of 0.2 mm, a temperature rise rate of 10 ° C./min, a frequency of 1 Hz, and a measurement temperature range of 20 to 250 ° C., and the minimum melt viscosity and the minimum melt viscosity reached temperature were read.

[Creation of connection structure]
As the first electronic component, a printed wiring board [0.35 mm pitch (line / space = 0.18 / 0.17 mm), glass epoxy base material thickness 1.5 mm, copper pattern thickness 18 μm, surface OSP treatment] was prepared. ..

As a second electronic component, a commercially available connector component (BM23FR 0.6-20DP, 0.35 mmP, line / space = 0.12 / 0.23 mm, terminal surface Au plating, terminal area / 34800 μm ² , 20 pins manufactured by Hirose) Prepared.

An anisotropic conductive film was cut into a predetermined size on the terminals of the first electronic component, and temporarily pressure-bonded under the conditions of 45 ° C., 1 MPa, and 1 second. Subsequently, a second electronic component was placed on the anisotropic conductive film. This structure was subjected to a reflow oven treatment under the temperature profile conditions shown in FIG. 7 to prepare a connected structure.

[Evaluation of solder joint condition]
The molten state of the solder on the terminals of the printed wiring board after the reflow treatment was observed with a metal microscope, the solder area with respect to the wiring area was measured, and the evaluation was made according to the following evaluation criteria.
AA: Solder particles are sufficiently wet and spread on the wiring (solder area is 70% or more)
A: Solder particles are wet and spread on the wiring (solder area is 50 to 70%)
B: Solder particles are partially wet and spread on the wiring (solder area is 30 to 50%).
C: Solder particles on the wiring are hardly wet and spread (solder area is less than 30%)

[Evaluation of conduction resistance value]
Using a digital multimeter, the conduction resistance value of the connection structure when DC10 mA was passed by the 4-terminal method was measured. The conduction resistance value of the connection structure was measured for pin 20 and evaluated according to the following evaluation criteria.
AA: Resistance value is less than 0.1Ω A: Resistance value is 0.1Ω or more and less than 0.2Ω B: Resistance value is 0.2Ω or more and less than 0.5Ω C: Resistance value is 0.5Ω or more

[Evaluation of insulation resistance value]
Using a digital multimeter, the insulation resistance value of the connection structure when a voltage of 20 V was applied between the adjacent terminals was measured. The insulation resistance value of the connection structure was measured for pin 10 and evaluated according to the following evaluation criteria.
A: Resistance value is 109 Ω or more B: Resistance value is ¹⁰⁸ Ω or more and less than ^{10 9} Ω C: Resistance value is less than ¹⁰⁸ Ω

<Examples 1 to 4 and Comparative Examples 1 and 2>
Table 2 shows the results of the evaluation of solder wetting, the evaluation of the continuity test, and the evaluation of the insulation test with respect to the Sn amount of the solder particles. Further, FIG. 8 is a graph showing the measurement result of the melt viscosity of the anisotropic conductive film of Example 2 and the measurement result of DSC. Further, FIGS. 9 to 12 are micrographs on the terminals of the printed wiring board after the reflow oven treatment of Examples 2 and 3 and Comparative Examples 1 and 2, respectively.

In Comparative Example 1, since the amount of Sn of the solder particles is large and the melting point of the solder particles used is too high, good evaluation of solder wetting cannot be obtained as shown in FIG. 11, and evaluation of the continuity test and evaluation of the insulation test cannot be obtained. Was C. In Comparative Example 2, since the Sn amount of the solder particles is small and the movement of the solder particles on the wiring due to aggregation is small, a good evaluation of solder wetting cannot be obtained as shown in FIG. 12, and the evaluation of the continuity test is C. Met.

On the other hand, in Examples 1 to 4, since the solder particles contain 50 to 80 wt% Sn and 20 to 50 wt% Bi, good solder wetting is achieved in the reflow oven treatment under the temperature profile condition shown in FIG. The evaluation, the evaluation of the continuity test, and the evaluation of the insulation test could be obtained. In particular, in Examples 2 and 3, as shown in FIGS. 9 and 10, it was found that the movement of the solder particles on the wiring was good.

<Examples 5 to 9 and Comparative Examples 3 to 6>
Table 3 shows the results of the evaluation of solder wetting, the evaluation of the continuity test, and the evaluation of the insulation test with respect to the blending amount of the solder particles and the average particle size of the solder particles.

In Comparative Example 3, since the blending amount of the solder particles was too small, the evaluation of the solder wetting was B, and the evaluation of the continuity test was C. In Comparative Example 4, since the amount of solder particles having an average particle size of 30 μm was too large, a short circuit occurred between adjacent terminals, and the insulation test was evaluated as C. However, as will be described later, the particle size is reduced. This makes it possible to further fill the solder particles. It is considered that this is because the small particle diameter increases the mobility of the solder particles themselves in the binder, increases the amount of solder particles that can aggregate, and reduces the amount of solder particles remaining between the wirings.

In Comparative Example 5, since the average particle size of the solder particles is 5 μm, there are many relative surface oxide films, excessive aggregation of the solder particles in a state where the solder particles are not bonded to each other occurs excessively, and the solder particles are not between adjacent terminals. The evaluation of the insulation test was C because of the generation of huge aggregates of bonds, but as will be described later, it is possible to improve the evaluation of the insulation test by increasing the amount of dicarboxylic acid. In Comparative Example 6, since the average particle size of the solder particles was too large, 50 μm, a short circuit occurred between the adjacent terminals, and the evaluation of the insulation test was C.

On the other hand, in Examples 2, 5 and 6, since the blending amount of the solder particles having an average particle size of 30 μm is 100 to 300 parts by mass with respect to 100 parts by mass of the thermosetting binder, the solder particles are placed on the wiring due to aggregation. The movement of the particles occurred moderately, and good evaluation of solder wetting, evaluation of continuity test, and evaluation of insulation test could be obtained. In particular, in Examples 2 and 5, it was found that the movement of the solder particles onto the wiring was good. Further, in Examples 7 to 9, since the average particle size of the solder particles is 10 to 40 μm, the solder particles are appropriately moved onto the wiring due to aggregation, and good evaluation of solder wetting, evaluation of continuity test, and evaluation of continuity test are performed. We were able to obtain an evaluation of the insulation test.

<Examples 10 to 16 and Comparative Examples 7 and 8>
Table 4 shows the results of evaluation of solder wetting, evaluation of continuity test, and evaluation of insulation test when solder particles having an average particle size of 20 μm and 10 μm are blended.

In Comparative Example 7, since the amount of the solder particles having an average particle size of 20 μm was too large, a short circuit occurred between the adjacent terminals, and the insulation test was evaluated as C. In Comparative Example 8, the solder particles having an average particle size of 10 μm were also evaluated. Since the amount of the soldering was too large, a short circuit occurred between the adjacent terminals, and the evaluation of the insulation test was C.

On the other hand, in Examples 10 to 13, since the blending amount of the solder particles having an average particle size of 20 μm is 400 to 900 parts by mass with respect to 100 parts by mass of the thermosetting binder, the solder particles move onto the wiring due to aggregation. Appropriately occurred, and good evaluation of solder wetting, evaluation of continuity test, and evaluation of insulation test could be obtained. Further, in Examples 14 to 16, since the blending amount of the solder particles having an average particle size of 10 μm is 1000 to 1200 parts by mass with respect to 100 parts by mass of the thermosetting binder, the solder particles move onto the wiring due to aggregation. Appropriately occurred, and good evaluation of solder wetting, evaluation of continuity test, and evaluation of insulation test could be obtained.

<Examples 17 to 22>
Table 5 shows the results of the evaluation of solder wetting, the evaluation of the continuity test, and the evaluation of the insulation test when the blending amount of the dicarboxylic acid was changed.

In Examples 17 to 19, the amount of dicarboxylic acid was increased to 6 to 10 parts by mass with respect to 100 parts by mass of the thermosetting binder as compared with Comparative Example 5, so that the solder particles were aggregated in a state where the solder particles were not bonded to each other. Was reduced, and a good connection could be obtained. Further, in Examples 20 to 22, the average particle size of the solder particles was 10, 20, and 30 μm, respectively, and even when 10 parts by mass of the dicarboxylic acid was blended with 100 parts by mass of the thermosetting binder, good solder wetting was achieved. The evaluation, the evaluation of the continuity test, and the evaluation of the insulation test could be obtained.

Further, from Examples 17 to 19 (average particle size 5 μm, film thickness 35 μm) and Example 9 (average particle size 40 μm, film thickness 45 μm), the thickness of the anisotropic conductive film is 110, which is the average particle size of the solder particles. It was found that if the range is more than% and 700% or less, the solder particles move to the wiring due to aggregation moderately, and good evaluation of solder wetting, evaluation of continuity test, and evaluation of insulation test can be obtained. ..

<Examples 23 to 28 and Comparative Example 9>
Table 6 shows the results of the evaluation of solder wetting with respect to the carbon number of the dicarboxylic acid, the evaluation of the continuity test, and the evaluation of the insulation test. Further, FIG. 13 is a photomicrograph of the terminals of the printed wiring board after the reflow oven treatment of Comparative Example 9.

In Comparative Example 9, since the dicarboxylic acid was not contained, the surface acid film of the solder particles could not be removed, solder melting was not observed as shown in FIG. 13, and the evaluation of solder wetting and the evaluation of the continuity test were C. there were.

On the other hand, since Examples 2 and 23 to 26 contain glutaric acid, malonic acid, adipic acid, suberic acid, and sebacic acid as dicarboxylic acids, respectively, good evaluation of solder wetting, evaluation of continuity test, and insulation are performed. I was able to get an evaluation of the test. In particular, in Examples 2 and 23, it was found that the movement of the solder particles on the wiring was good. Further, as shown in Examples 27 and 28, even when dicyandiamide and isophthalic acid dihydrazide were used as the curing agents, good evaluation of solder wetting, evaluation of continuity test, and evaluation of insulation test could be obtained. ..

10 anisotropic conductive film, 11 solder particles, 20 first electronic component, 21 first terminal row, 30 anisotropic conductive film, 31 solder particles, 32 solder, 40 second electronic component, 41 second Terminal row, 50 tools

Claims (20)

Contains a thermosetting binder, solder particles, and a dicarboxylic acid,
The solder particles contain 50-80 wt% Sn and 20-50 wt% Bi.
A conductive adhesive having a blending amount of the solder particles of 100 parts by mass or more with respect to 100 parts by mass of the thermosetting binder. The conductive adhesive according to claim 1, wherein the dicarboxylic acid is a compound (n = 1 to 8) represented by the following formula (1).

The conductive adhesive according to claim 1, wherein the dicarboxylic acid is a compound (n = 1 to 3) represented by the following formula (1).

The conductive adhesive according to any one of claims 1 to 3, wherein the minimum melt viscosity of the conductive adhesive is 300 Pa · s or less. The conductive adhesive according to any one of claims 1 to 4, wherein the solder particles are 59.9Sn-40Bi-0.1Cu or 69.5Sn-30Bi-0.5Cu. Contains a thermosetting binder, solder particles, and a dicarboxylic acid,
The solder particles contain 50-80 wt% Sn and 20-50 wt% Bi.
The blending amount of the solder particles with respect to the average particle size of the solder particles of 40 to 5 μm is 100 to 1200 parts by mass with respect to 100 parts by mass of the thermosetting binder.
An anisotropic conductive film having a thickness of more than 110% and 700% or less of the average particle size of the solder particles. The anisotropic conductive film according to claim 6, wherein the dicarboxylic acid is a compound (n = 1 to 8) represented by the following formula (1).

The anisotropic conductive film according to claim 6, wherein the dicarboxylic acid is a compound (n = 1 to 3) represented by the following formula (1).

The anisotropic conductive film according to any one of claims 6 to 8, wherein the minimum melt viscosity of the anisotropic conductive film is 300 Pa · s or less. The anisotropic conductive film according to any one of claims 6 to 9, wherein the solder particles are 59.9Sn-40Bi-0.1Cu or 69.5Sn-30Bi-0.5Cu. The item according to any one of claims 6 to 10, wherein the blending amount of the solder particles with respect to the average particle size of the solder particles of 30 to 10 μm is 100 to 1200 parts by mass with respect to 100 parts by mass of the thermosetting binder. Anisotropic conductive film. The item according to any one of claims 6 to 10, wherein the blending amount of the solder particles with respect to the average particle size of the solder particles of 30 to 20 μm is 100 to 900 parts by mass with respect to 100 parts by mass of the thermosetting binder. Anisotropic conductive film. The item according to any one of claims 6 to 10, wherein the blending amount of the solder particles with respect to the average particle size of the solder particles of 20 to 10 μm is 100 to 1200 parts by mass with respect to 100 parts by mass of the thermosetting binder. Anisotropic conductive film. The anisotropic conductive film according to any one of claims 6 to 13, wherein the amount of the dicarboxylic acid blended is 1 to 15 parts by mass with respect to 100 parts by mass of the thermosetting binder. The anisotropic conductive film according to any one of claims 6 to 13, wherein the amount of the dicarboxylic acid blended is 6 to 10 parts by mass with respect to 100 parts by mass of the thermosetting binder. The anisotropic conductive film according to any one of claims 6 to 15, which contains a rosin-based carboxylic acid instead of the dicarboxylic acid, or further contains a rosin-based carboxylic acid. The anisotropic conductive film according to any one of claims 6 to 16, wherein the thickness of the anisotropic conductive film is 5 μm or more larger than the average particle size of the solder particles. It is interposed between the first electronic component, the second electronic component, the electrode of the first electronic component, and the electrode of the second electronic component, and according to any one of claims 1 to 5. The conductive adhesive according to the above, or a cured film obtained by curing the anisotropic conductive film according to any one of claims 6 to 17 is provided.
A connection structure in which the solder area of the solder particles is 50% or more of the electrode area of the first electronic component or the electrode area of the second electronic component. The conductive adhesive according to any one of claims 1 to 5 or the anisotropic conductive film according to any one of claims 6 to 17 is used as an electrode of a first electronic component. Intervene between the electrodes of the electronic component 2
A method for manufacturing a connection structure in which an electrode of the first electronic component and an electrode of the second electronic component are joined without a load by using a reflow furnace. Contains a thermosetting binder, solder particles, and a dicarboxylic acid,
The solder particles contain 50-80 wt% Sn and 20-50 wt% Bi.
The blending amount of the solder particles is 100 to 300 parts by mass with respect to 100 parts by mass of the thermosetting binder.
An anisotropic conductive film having a thickness of more than 110% and 500% or less of the average particle size of the solder particles.

Images