JP7377007B2 - Conductive material, connected structure, and method for manufacturing connected structure - Google Patents

Description

The present invention relates to conductive materials containing conductive particles. The present invention also relates to a connected structure using the above-mentioned conductive material and a method for manufacturing the connected structure.

Anisotropic conductive materials such as anisotropic conductive pastes and anisotropic conductive films are widely known. In the above anisotropic conductive material, conductive particles are dispersed in a binder resin.

The above-mentioned anisotropic conductive material is used to obtain various connected structures. Examples of connections using the anisotropic conductive material include connections between flexible printed circuit boards and glass substrates (FOG (Film on Glass)), connections between semiconductor chips and flexible printed circuit boards (COF (Chip on Film)), and semiconductor Examples include connection between a chip and a glass substrate (COG (Chip on Glass)), connection between a flexible printed circuit board and a glass epoxy substrate (FOB (Film on Board)), and the like.

For example, when electrically connecting the electrodes of a flexible printed circuit board and the electrodes of a glass epoxy board using the anisotropic conductive material, the anisotropic conductive material containing conductive particles is placed on the glass epoxy board. do. Next, flexible printed circuit boards are laminated and heated and pressurized. Thereby, the anisotropic conductive material is cured, the electrodes are electrically connected via the conductive particles, and a connected structure is obtained.

Patent Document 1 listed below discloses a conductive paste containing a binder resin and conductive particles. In the conductive paste, the binder resin contains a thermally radically polymerizable compound and a thermally radical polymerization initiator. In the conductive paste, the binder resin has a storage modulus of 8 Pa or more and less than 500 MPa at 90°C, or the conductive paste has a storage modulus of 8 Pa or more and less than 500 MPa.

Japanese Patent Application Publication No. 2015-005502

In recent years, the trend toward finer pitch wiring in printed wiring boards and the like has progressed. Along with this, in conductive materials containing solder particles or conductive particles having solder on their surfaces, the solder particles or conductive particles having solder on their surfaces are becoming smaller and smaller in particle size.

If solder particles or the like are simply reduced in particle size, there is a problem that the solder particles or the like cannot be efficiently arranged between the upper and lower electrodes to be connected during conductive connection using a conductive material. In particular, when heating and curing conductive materials, solder particles, etc., cannot be sufficiently aggregated between the vertical electrodes that should be connected, and the viscosity of the conductive material increases. Solder particles may remain between the electrodes as side balls, separated from the solder between the electrodes in the vertical direction. As a result, it may not be possible to sufficiently improve the continuity reliability between electrodes that should be connected and the insulation reliability between adjacent electrodes that should not be connected.

An object of the present invention is to provide a conductive material that allows efficient placement of solder on electrodes. Another object of the present invention is to provide a connected structure using the above conductive material and a method for manufacturing the connected structure.

According to a broad aspect of the present invention, the conductive material is a conductive material containing a thermosetting component, a flux, and conductive particles including solder, and the conductive material is applied to a substrate whose surface material is gold, and When heated to 1.0x, the maximum value of the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is 1.0x10 ^-23 m ² /s or more. 10 ⁻¹⁴ m ² /s or less is provided.

According to a broad aspect of the present invention, the conductive material is a conductive material containing a thermosetting component, a flux, and conductive particles including solder, and the conductive material is applied to a substrate whose surface material is silver, When heated to 1.0x, the maximum value of the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is 1.0x10 ^-23 m ² /s or more. 10 ⁻¹⁴ m ² /s or less is provided.

According to a broad aspect of the present invention, the conductive material is applied to a substrate including a thermosetting component, a flux, and conductive particles including solder, and the surface material is copper, and the conductive material is applied at 70°C. When heated to 1.0x, the maximum value of the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is 1.0x10 ^-23 m ² /s or more. 10 ⁻¹⁴ m ² /s or less is provided.

According to a broad aspect of the present invention, the conductive material is applied to a substrate containing a thermosetting component, a flux, and conductive particles including solder, and the surface material is aluminum, and the conductive material is applied at 70°C. When heated to 1.0x, the maximum value of the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is 1.0x10 ^-23 m ² /s or more. 10 ⁻¹⁴ m ² /s or less is provided.

In certain aspects of the conductive material according to the invention, the flux is a liquid at 23°C.

In a particular aspect of the conductive material according to the present invention, the conductive particles containing the solder have a particle size of 35 μm or less.

In a particular aspect of the conductive material according to the present invention, the conductive material is a conductive paste.

According to a broad aspect of the present invention, a first connection target member having a first electrode on its surface, a second connection target member having a second electrode on its surface, and the first connection target member, a connecting portion connecting the second connection target member, the material of the connecting portion is the above-mentioned conductive material, and the first electrode and the second electrode are connected to the connecting portion. A connection structure is provided that is electrically connected by a solder portion therein.

According to a broad aspect of the present invention, a conductive material containing a thermosetting component, a flux, and conductive particles including solder is used to coat a surface of a first connection target member having a first electrode on the surface. a first step of arranging the conductive material, and placing a second connection target member having a second electrode on the surface on a surface of the conductive material opposite to the first connection target member side; A second step of arranging the first electrode and the second electrode to face each other, and heating the conductive material above the melting point of the conductive particles to connect the first member to be connected. A connecting portion connecting the second connection target member is formed of the conductive material, and the first electrode and the second electrode are electrically connected by a solder portion in the connecting portion. and a third step of connecting the conductive material to the substrate, the surface material of which is the same as the material of the surface of the first electrode as a combination of the surface material of the first electrode and the conductive material. When the material is applied and heated to 70°C, the maximum value of the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is 1.0 × 10 ^-23 m ² Provided is a method for manufacturing a connected structure using a material for the surface of the first electrode and a conductive material having a velocity of 1.0×10 ^{−14 m 2 /s or more and 1.0×10 −14} m ² /s or less.

In a particular aspect of the method for manufacturing a connected structure according to the present invention, as the combination of the surface material of the second electrode and the conductive material, the surface material is the same as the surface material of the second electrode. When the conductive material is applied on a certain substrate and heated to 70° C., the maximum value of the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is 1.0. A material and a conductive material for the surface of the second electrode are used that have a speed of not less than ×10 ⁻²³ m ² /s and not more than 1.0×10 ⁻¹⁴ m ² /s.

In a particular aspect of the method for manufacturing a connected structure according to the present invention, the first electrode and the second electrode are gold electrodes, silver electrodes, copper electrodes, or aluminum electrodes.

The electrically conductive material according to the present invention includes a thermosetting component, a flux, and electrically conductive particles containing solder. In the conductive material according to the present invention, when the conductive material is applied to a substrate whose surface material is gold and heated to 70°C, the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is Among them, the diffusion coefficient having the maximum value is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less. Since the conductive material according to the present invention has the above configuration, it is possible to efficiently arrange the solder on the electrode.

The electrically conductive material according to the present invention includes a thermosetting component, a flux, and electrically conductive particles containing solder. In the conductive material according to the present invention, when the conductive material is applied to a substrate whose surface material is silver and heated to 70°C, the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is Among them, the diffusion coefficient having the maximum value is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less. Since the conductive material according to the present invention has the above configuration, it is possible to efficiently arrange the solder on the electrode.

The electrically conductive material according to the present invention includes a thermosetting component, a flux, and electrically conductive particles containing solder. In the conductive material according to the present invention, when the conductive material is applied to a substrate whose surface material is copper and heated to 70°C, the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is Among them, the diffusion coefficient having the maximum value is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less. Since the conductive material according to the present invention has the above configuration, it is possible to efficiently arrange the solder on the electrode.

The electrically conductive material according to the present invention includes a thermosetting component, a flux, and electrically conductive particles containing solder. In the conductive material according to the present invention, when the conductive material is applied to a substrate whose surface material is aluminum and heated to 70°C, the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is Among them, the diffusion coefficient having the maximum value is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less. Since the conductive material according to the present invention has the above configuration, it is possible to efficiently arrange the solder on the electrode.

A method for manufacturing a connected structure according to the present invention uses a conductive material containing a thermosetting component, a flux, and conductive particles containing solder to produce a first connection target member having a first electrode on its surface. a first step of disposing the conductive material on the surface of the conductive material. The method for manufacturing a connected structure according to the present invention includes a method for manufacturing a connected structure, in which a second connection target member having a second electrode on the surface is placed on a surface of the conductive material opposite to the first connection target member side. The method includes a second step of arranging the first electrode and the second electrode to face each other. The method for manufacturing a connected structure according to the present invention connects the first connection target member and the second connection target member by heating the conductive material above the melting point of the conductive particles. A third step is provided in which a connecting portion is formed of the conductive material, and the first electrode and the second electrode are electrically connected by a solder portion in the connecting portion. In the method for manufacturing a connected structure according to the present invention, the following first electrode surface material and conductive material are used as a combination of the first electrode surface material and the conductive material. When the conductive material is coated on a substrate whose surface material is the same as that of the first electrode and heated to 70°C, the amount of metal contained in the conductive particles calculated by EPMA analysis is A material and a conductive material for the surface of the first electrode whose maximum diffusion coefficient is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less . Since the method for manufacturing a connected structure according to the present invention includes the above-mentioned configuration, solder can be efficiently placed on the electrodes.

FIG. 1 is a cross-sectional view schematically showing a connected structure obtained using a conductive material according to an embodiment of the present invention. FIGS. 2(a) to 2(c) are cross-sectional views for explaining each step of an example of a method for manufacturing a connected structure using a conductive material according to an embodiment of the present invention. FIG. 3 is a sectional view showing a modification of the connected structure. FIG. 4 is a cross-sectional view showing conductive particles that can be used in the conductive material according to the first embodiment of the present invention. FIG. 5 is a cross-sectional view showing conductive particles that can be used in the conductive material according to the second embodiment of the present invention. FIG. 6 is a cross-sectional view showing conductive particles that can be used in a conductive material according to a third embodiment of the present invention.

The details of the present invention will be explained below.

(conductive material)
The electrically conductive material according to the present invention includes a thermosetting component, a flux, and electrically conductive particles containing solder. In the conductive material according to the present invention, when the conductive material is applied to a substrate whose surface material is gold and heated to 70°C, the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is Among them, the diffusion coefficient having the maximum value is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less.

The electrically conductive material according to the present invention includes a thermosetting component, a flux, and electrically conductive particles containing solder. In the conductive material according to the present invention, when the conductive material is applied to a substrate whose surface material is silver and heated to 70°C, the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is Among them, the diffusion coefficient having the maximum value is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less.

The electrically conductive material according to the present invention includes a thermosetting component, a flux, and electrically conductive particles containing solder. In the conductive material according to the present invention, when the conductive material is applied to a substrate whose surface material is copper and heated to 70°C, the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is Among them, the diffusion coefficient having the maximum value is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less.

The electrically conductive material according to the present invention includes a thermosetting component, a flux, and electrically conductive particles containing solder. In the conductive material according to the present invention, when the conductive material is applied to a substrate whose surface material is aluminum and heated to 70°C, the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is Among them, the diffusion coefficient having the maximum value is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less.

Since the conductive material according to the present invention has the above configuration, it is possible to efficiently arrange the solder on the electrode.

With a conductive material in which conductive particles are simply reduced in particle size, the conductive particles may not be efficiently arranged on the vertical electrodes to be connected during conductive connection. For this reason, conductive particles may remain as side balls or the like between the horizontal electrodes that should not be connected, separated from the solder between the vertical electrodes. Furthermore, it may not be possible to sufficiently improve the continuity reliability between electrodes that should be connected and the insulation reliability between adjacent electrodes that should not be connected.

The present inventors focused on metal diffusion into electrodes, and found that by using a conductive material that satisfies a specific diffusion coefficient relationship during conductive connection between electrodes, it is possible to efficiently place solder on the electrodes. I found out. In the present invention, even when the solder particles have a small particle diameter, the solder can be efficiently placed between the electrodes to be connected, and the conduction reliability and insulation reliability can be improved.

Further, in the present invention, when conductive connection is made between the electrodes, a plurality of conductive particles easily gather between the upper and lower opposing electrodes, and a plurality of conductive particles can be arranged on the electrode (line). In addition, it is difficult for some of the plurality of conductive particles to be placed between horizontal electrodes that should not be connected, and the amount of conductive particles that are placed between horizontal electrodes that must not be connected is considerably reduced. be able to. As a result, in the present invention, the amount of solder remaining between the horizontal electrodes that should not be connected can be reduced.

In the present invention, the use of a conductive material that satisfies a specific diffusion coefficient relationship greatly contributes to obtaining the above effects.

Furthermore, in the present invention, positional displacement between the electrodes can be prevented. In the present invention, when the second connection target member is superimposed on the first connection target member having a conductive material disposed on the upper surface, the electrodes of the first connection target member and the second connection target member are connected to each other. Even in a state where the alignment is misaligned, the misalignment can be corrected and the electrodes can be connected to each other (self-alignment effect).

From the viewpoint of disposing the solder on the electrodes more efficiently, the conductive material is preferably liquid at 25° C., and is preferably a conductive paste.

From the viewpoint of disposing the solder on the electrode more efficiently, the viscosity (η25) at 25°C of the conductive material is preferably 30 Pa·s or more, more preferably 50 Pa·s or more, and preferably 400 Pa·s. -s or less, more preferably 300 Pa.s or less. The above viscosity (η25) can be adjusted as appropriate depending on the types and amounts of the ingredients.

The viscosity (η25) can be measured, for example, using an E-type viscometer (“TVE22L” manufactured by Toki Sangyo Co., Ltd.) at 25° C. and 5 rpm.

In the conductive material according to the present invention, when the conductive material is applied to a substrate whose surface material is gold and heated to 70°C, the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is Among them, the diffusion coefficient (DAu) which shows the maximum value is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less. The diffusion coefficient (DAu) showing the above maximum value is preferably 1.0×10 ⁻²¹ m ² /s or more, more preferably 1.0×10 ⁻²⁰ m ² /s or more, and preferably 1.0 ×10 ⁻¹⁴ m ² /s or less, more preferably 1.0×10 ⁻¹⁸ m ² /s or less. When the diffusion coefficient (DAu) indicating the above maximum value is above the above lower limit and below the above upper limit, the solder can be placed on the electrode even more efficiently, and the continuity reliability and insulation reliability are further improved. can be improved.

In the conductive material according to the present invention, when the conductive material is applied to a substrate whose surface material is silver and heated to 70°C, the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is Among them, the diffusion coefficient (DAg) which shows the maximum value is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less. The diffusion coefficient (DAg) showing the above maximum value is preferably 1.0×10 ⁻²¹ m ² /s or more, more preferably 1.0×10 ⁻²⁰ m ² /s or more, and preferably 1.0 ×10 ⁻¹⁴ m ² /s or less, more preferably 1.0×10 ⁻¹⁸ m ² /s or less. When the diffusion coefficient (DAg) indicating the maximum value is greater than or equal to the lower limit and less than the upper limit, solder can be placed on the electrode more efficiently, and continuity reliability and insulation reliability are further improved. can be improved.

In the conductive material according to the present invention, when the conductive material is applied to a substrate whose surface material is copper and heated to 70°C, the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is Among them, the diffusion coefficient (DCu) which shows the maximum value is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less. The diffusion coefficient (DCu) showing the above maximum value is preferably 1.0×10 ⁻²³ m ² /s or more, more preferably 1.0×10 ⁻²¹ m ² /s or more, and preferably 1.0 ×10 ⁻¹⁴ m ² /s or less, more preferably 1.0×10 ⁻¹⁸ m ² /s or less. When the diffusion coefficient (DCu) showing the above maximum value is above the above lower limit and below the above upper limit, the solder can be placed on the electrode even more efficiently, and the continuity reliability and insulation reliability are further improved. can be improved.

In the conductive material according to the present invention, when the conductive material is applied to a substrate whose surface material is aluminum and heated to 70°C, the diffusion coefficient of the metal contained in the conductive particles calculated by EPMA analysis is Among them, the diffusion coefficient (DAl) which shows the maximum value is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less. The diffusion coefficient (DAl) showing the above maximum value is preferably 1.0×10 ⁻²¹ m ² /s or more, more preferably 1.0×10 ⁻²⁰ m ² /s or more, and preferably 1.0 ×10 ⁻¹⁴ m ² /s or less, more preferably 1.0×10 ⁻¹⁸ m ² /s or less. When the diffusion coefficient (DAl) indicating the maximum value is greater than or equal to the lower limit and less than or equal to the upper limit, solder can be placed on the electrode more efficiently, and continuity reliability and insulation reliability are further improved. can be improved.

The diffusion coefficients (DAu, DAg, DCu, and DAl) showing the above-mentioned maximum values can be calculated by EPMA analysis. Examples of the EPMA analyzer include "JXA-8200" manufactured by JEOL Ltd. Specifically, the diffusion coefficients (DAu, DAg, DCu, and DAl) exhibiting the above maximum values can be measured as follows.

Various metal substrates (5 cm x 5 cm) such as a copper substrate, a copper substrate, and an aluminum substrate whose surfaces are plated with gold or silver are prepared. A conductive material is uniformly applied to various prepared metal substrates using a metal mask (thickness: 70 μm, size: 1 cm×1 cm), and heated at 80° C. for 30 minutes. Thereafter, the metal substrate is cut at the portion coated with the conductive material, and an EPMA analysis is performed on the cross section. In EPMA analysis, the origin is the intersection of the metal spectrum of various metal substrates and the spectrum of metal contained in conductive particles, and the distance from which the metal contained in conductive particles is not detected in the direction of the metal of various metal substrates is set as the origin. , calculate the moving distance (m) of the conductive particles to the various metal substrates. The distance traveled by the conductive particles in one direction toward the various metal substrates is squared, and the diffusion coefficient (m ² /s) is calculated from the square of the distance traveled (m ² ) and the heating time (s). The value of the equation: square of moving distance (m ² )/heating time (s) is taken as the diffusion coefficient (m ² /s). Furthermore, the irradiation voltage of the EPMA analyzer is 15.0 kV.

Examples of methods for adjusting the diffusion coefficients (DAu, DAg, DCu, and DAl) exhibiting the above-mentioned maximum values to the above-mentioned preferable ranges include a method of activating metal diffusion. Specifically, a method using a flux having low temperature activity can be mentioned.

The above-mentioned conductive material can be used as a conductive paste, a conductive film, and the like. The conductive paste is preferably an anisotropic conductive paste, and the conductive film is preferably an anisotropic conductive film. From the viewpoint of arranging the solder on the electrodes more efficiently, the conductive material is preferably a conductive paste. The above-mentioned conductive material is suitably used for electrical connection of electrodes. Preferably, the conductive material is a circuit connection material.

Each component contained in the above conductive material will be explained below.

(conductive particles)
The electrically conductive material includes electrically conductive particles. The conductive particles include solder. The conductive particles may contain only solder, or may contain solder and a metal other than solder.

The conductive particles may be solder particles. The conductive particles may be conductive particles containing solder other than solder particles. The conductive particles may include a base particle and a conductive part disposed on the surface of the base particle. The conductive portion may include solder. The conductive material may contain only solder particles, or may contain conductive particles containing solder other than solder particles.

The particle diameter of the conductive particles is preferably 2 μm or more, more preferably 5 μm or more, and preferably 35 μm or less, more preferably 20 μm or less. When the particle diameter of the conductive particles is not less than the above lower limit and not more than the above upper limit, the solder can be placed on the electrode even more efficiently, and the conduction reliability and connection reliability are further effectively increased. be able to. It is particularly preferable that the particle diameter of the conductive particles is 15 μm or less. When the particle diameter of the conductive particles is 15 μm or less, the solder can be disposed on the electrode more efficiently, and the conduction reliability and connection reliability can be further effectively improved.

The particle diameter of the conductive particles is preferably an average particle diameter, more preferably a number average particle diameter. The particle diameter of the conductive particles can be determined, for example, by observing 50 arbitrary conductive particles with an electron microscope or optical microscope and calculating the average value of the particle diameter of each conductive particle, or by laser diffraction particle size distribution measurement. It can be found by doing the following. In observation using an electron microscope or an optical microscope, the particle diameter of each conductive particle is determined as the particle diameter in equivalent circle diameter. In observation using an electron microscope or an optical microscope, the average particle diameter of any 50 conductive particles in equivalent circle diameter is approximately equal to the average particle diameter in equivalent sphere diameter. In the laser diffraction particle size distribution measurement, the particle diameter of each conductive particle is determined as the particle diameter in equivalent sphere diameter. The particle diameter of the conductive particles is preferably calculated by laser diffraction particle size distribution measurement.

The content of the conductive particles in 100% by weight of the conductive material is preferably 40% by weight or more, more preferably 45% by weight or more, even more preferably 55% by weight or more, particularly preferably 60% by weight or more, and preferably is 90% by weight or less, more preferably 85% by weight or less, even more preferably 80% by weight or less. When the content of the conductive particles is not less than the lower limit and not more than the upper limit, the solder can be placed on the electrodes even more efficiently, and it is easy to place a large amount of solder between the electrodes, Continuity reliability and insulation reliability can be improved even more effectively.

Next, specific examples of conductive particles will be described with reference to the drawings.

FIG. 4 is a cross-sectional view showing conductive particles that can be used in the conductive material according to the first embodiment of the present invention.

The conductive particles 21 shown in FIG. 4 are solder particles. The conductive particles 21 are entirely made of solder. The conductive particles 21 do not have a base particle in their core and are not core-shell particles. Both the center portion and the outer surface portion of the conductive part of the conductive particles 21 are formed of solder.

FIG. 5 is a cross-sectional view showing conductive particles that can be used in the conductive material according to the second embodiment of the present invention.

The conductive particles 31 shown in FIG. 5 include a base particle 32 and a conductive part 33 disposed on the surface of the base particle 32. The conductive portion 33 covers the surface of the base particle 32. The conductive particles 31 are coated particles in which the surface of a base particle 32 is coated with a conductive part 33 .

The conductive part 33 includes a second conductive part 33A and a first conductive part 33B. The conductive particles 31 include a second conductive part 33A between the base particle 32 and the first conductive part 33B. Therefore, the conductive particles 31 include the base particles 32, the second conductive part 33A disposed on the surface of the base particle 32, and the first conductive part 33A disposed on the outer surface of the second conductive part 33A. A conductive part 33B is provided.

FIG. 6 is a cross-sectional view showing conductive particles that can be used in a conductive material according to a third embodiment of the present invention.

As described above, the conductive part 33 in the conductive particle 31 has a two-layer structure. The conductive particles 41 shown in FIG. 6 have a conductive part 42 as a single-layer conductive part. The conductive particles 41 include a base particle 32 and a conductive part 42 arranged on the surface of the base particle 32.

Other details of the conductive particles will be explained below.

Solder particles:
Both the center portion and the outer surface of the solder particles are made of solder. The solder particles described above are particles in which both the center portion and the outer surface are solder.

The solder is preferably a metal having a melting point of 450° C. or lower (low melting point metal). The solder particles are preferably metal particles having a melting point of 450° C. or lower (low-melting point metal particles). The low melting point metal particles are particles containing a low melting point metal. The low melting point metal refers to a metal having a melting point of 450° C. or lower. The melting point of the low melting point metal is preferably 300°C or lower, more preferably 160°C or lower. The solder particles are preferably a low melting point solder having a melting point of less than 150°C.

The melting point of the solder particles can be determined by differential scanning calorimetry (DSC). Examples of the differential scanning calorimetry (DSC) device include "EXSTAR DSC7020" manufactured by SII.

Further, it is preferable that the solder particles contain tin. The content of tin is preferably 30% by weight or more, more preferably 40% by weight or more, still more preferably 70% by weight or more, and particularly preferably 90% by weight or more in 100% by weight of the metal contained in the solder particles. . When the content of tin in the solder particles is equal to or higher than the lower limit, the conduction reliability and connection reliability between the solder portion and the electrode will be further increased.

The above tin content was measured using a high frequency inductively coupled plasma emission spectrometer ("ICP-AES" manufactured by Horiba Ltd.) or a fluorescent X-ray analyzer ("EDX-800HS" manufactured by Shimadzu Corporation), etc. can be measured.

By using the above-mentioned solder particles, the solder particles are melted and bonded to the electrodes, and the solder portion establishes conduction between the electrodes. For example, since the solder portion and the electrode tend to make surface contact rather than point contact, the connection resistance becomes low. Furthermore, the use of the solder particles increases the bonding strength between the solder part and the electrode, making it even more difficult for the solder part to separate from the electrode, resulting in even higher conduction reliability and connection reliability.

The low melting point metal constituting the solder particles is not particularly limited. The low melting point metal is preferably tin or an alloy containing tin. Examples of the alloy include tin-silver alloy, tin-copper alloy, tin-silver-copper alloy, tin-bismuth alloy, tin-zinc alloy, and tin-indium alloy. The low melting point metal is preferably tin, a tin-silver alloy, a tin-silver-copper alloy, a tin-bismuth alloy, or a tin-indium alloy, since they have excellent wettability to the electrode. More preferably, the low melting point metal is a tin-bismuth alloy or a tin-indium alloy.

The solder particles are preferably filler metals whose liquidus line is 450° C. or less based on JIS Z3001: Welding terminology. Examples of the composition of the solder particles include metal compositions containing zinc, gold, silver, lead, copper, tin, bismuth, indium, and the like. Preferred are tin-indium (117° C. eutectic) or tin-bismuth (139° C. eutectic) which have a low melting point and are lead-free. That is, the solder particles preferably do not contain lead, and preferably contain tin and indium, or tin and bismuth.

In order to further increase the bonding strength between the solder part and the electrode, the solder particles include nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth, manganese, chromium, It may also contain metals such as molybdenum and palladium. Moreover, from the viewpoint of further increasing the bonding strength between the solder part and the electrode, it is preferable that the solder particles contain nickel, copper, antimony, aluminum, or zinc. From the viewpoint of further increasing the bonding strength between the solder part and the electrode, the content of these metals for increasing the bonding strength is preferably 0.0001% by weight or more based on 100% by weight of the metal contained in the solder particles, Preferably it is 1% by weight or less.

The particle diameter of the solder particles is preferably 2 μm or more, more preferably 5 μm or more, and preferably 35 μm or less, more preferably 20 μm or less. When the particle size of the solder particles is at least the above lower limit and below the above upper limit, the solder can be placed on the electrode even more efficiently, and the continuity reliability and connection reliability can be further effectively increased. I can do it. It is particularly preferable that the particle diameter of the solder particles is 15 μm or less. When the particle size of the solder particles is 15 μm or less, the solder can be disposed on the electrode more efficiently, and the conduction reliability and connection reliability can be further effectively improved.

The particle size of the solder particles is preferably an average particle size, more preferably a number average particle size. The particle size of the solder particles can be determined, for example, by observing 50 arbitrary solder particles with an electron microscope or optical microscope and calculating the average value of the particle size of each solder particle, or by performing laser diffraction particle size distribution measurement. It is determined by In observation using an electron microscope or an optical microscope, the particle diameter of each solder particle is determined as the particle diameter in equivalent circle diameter. In observation using an electron microscope or an optical microscope, the average particle diameter of any 50 solder particles in equivalent circle diameter is approximately equal to the average particle diameter in equivalent sphere diameter. In the laser diffraction particle size distribution measurement, the particle diameter of each solder particle is determined as the particle diameter in equivalent sphere diameter. The particle diameter of the solder particles is preferably calculated by laser diffraction particle size distribution measurement.

The coefficient of variation (CV value) of the particle diameter of the solder particles is preferably 5% or more, more preferably 10% or more, and preferably 40% or less, more preferably 30% or less. When the coefficient of variation of the particle diameter of the solder particles is greater than or equal to the lower limit and less than or equal to the upper limit, the solder can be disposed on the electrode even more efficiently. However, the CV value of the particle diameter of the solder particles may be less than 5%.

The above coefficient of variation (CV value) can be measured as follows.

CV value (%) = (ρ/Dn) x 100
ρ: Standard deviation of particle diameter of solder particles Dn: Average value of particle diameter of solder particles

The shape of the solder particles is not particularly limited. The shape of the solder particles may be spherical, a shape other than spherical, or a flat shape.

The content of the solder particles in 100% by weight of the conductive material is preferably 40% by weight or more, more preferably 45% by weight or more, even more preferably 55% by weight or more, particularly preferably 60% by weight or more, and preferably It is 90% by weight or less, more preferably 85% by weight or less, even more preferably 80% by weight or less. When the content of the solder particles is above the above lower limit and below the above upper limit, the solder can be placed on the electrodes even more efficiently, it is easy to place a large amount of solder between the electrodes, and conduction is ensured. Reliability and insulation reliability can be improved even more effectively.

Conductive particles containing solder other than solder particles (conductive particles X):
The conductive particles may be conductive particles containing solder other than the solder particles described above (hereinafter, conductive particles containing solder other than solder particles may be referred to as conductive particles X). The conductive particles X may include a base particle and a conductive part disposed on the surface of the base particle. The conductive particles X may include solder in the conductive portion. The conductive portion may have a single layer structure or a multilayer structure of two or more layers. The conductive particles X include a base particle, a second conductive part placed on the surface of the base particle, and a first conductive part placed on the outer surface of the second conductive part. may be provided.

Other details of the conductive particles X will be explained below.

(Base material particles)
Examples of the base particles include resin particles, inorganic particles other than metal particles, organic-inorganic hybrid particles, and metal particles. The base particles are preferably base particles excluding metal particles, and more preferably resin particles, inorganic particles excluding metal particles, or organic-inorganic hybrid particles. The base particle may be a core-shell particle including a core and a shell disposed on the surface of the core. The core may be an organic core, and the shell may be an inorganic shell.

Various organic substances are suitably used as materials for the resin particles. Materials for the resin particles include, for example, polyolefin resins such as polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyisobutylene, and polybutadiene; acrylic resins such as polymethyl methacrylate and polymethyl acrylate; polycarbonate, polyamide, Phenol formaldehyde resin, melamine formaldehyde resin, benzoguanamine formaldehyde resin, urea formaldehyde resin, phenolic resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, polyphenylene oxide, polyacetal, Examples include polyimide, polyamideimide, polyetheretherketone, polyethersulfone, divinylbenzene polymer, and divinylbenzene copolymer. Examples of the divinylbenzene copolymers include divinylbenzene-styrene copolymers and divinylbenzene-(meth)acrylic acid ester copolymers. Since the hardness of the resin particles can be easily controlled within a suitable range, the material of the resin particles is a polymer obtained by polymerizing one or more polymerizable monomers having ethylenically unsaturated groups. is preferred.

When the above-mentioned resin particles are obtained by polymerizing a polymerizable monomer having an ethylenically unsaturated group, the polymerizable monomer having an ethylenically unsaturated group may be a non-crosslinkable monomer. Examples include crosslinkable monomers.

Examples of the non-crosslinkable monomer include styrene monomers such as styrene and α-methylstyrene; carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, and maleic anhydride; Methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, cetyl (meth)acrylate, stearyl (meth)acrylate, Alkyl (meth)acrylate compounds such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate; 2-hydroxyethyl (meth)acrylate, glycerol (meth)acrylate, polyoxyethylene (meth)acrylate, and glycidyl (meth)acrylate Oxygen atom-containing (meth)acrylate compounds such as; nitrile-containing monomers such as (meth)acrylonitrile; vinyl ether compounds such as methyl vinyl ether, ethyl vinyl ether, and propyl vinyl ether; vinyl acetate, vinyl butyrate, vinyl laurate, and stearic acid. Acid vinyl ester compounds such as vinyl; unsaturated hydrocarbons such as ethylene, propylene, isoprene, and butadiene; trifluoromethyl (meth)acrylate, pentafluoroethyl (meth)acrylate, vinyl chloride, vinyl fluoride, and chlorostyrene, etc. Examples include halogen-containing monomers.

Examples of the crosslinkable monomer include tetramethylolmethanetetra(meth)acrylate, tetramethylolmethanetri(meth)acrylate, tetramethylolmethanedi(meth)acrylate, trimethylolpropanetri(meth)acrylate, dipenta Erythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, glycerol tri(meth)acrylate, glycerol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate Polyfunctional (meth)acrylate compounds such as acrylate, (poly)tetramethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate; triallyl(iso)cyanurate, triallyl trimellitate, divinylbenzene , diallyl phthalate, diallylacrylamide, diallyl ether, and silane-containing monomers such as γ-(meth)acryloxypropyltrimethoxysilane, trimethoxysilylstyrene, and vinyltrimethoxysilane.

The term "(meth)acrylate" refers to acrylates and methacrylates. The term "(meth)acrylic" refers to acrylic and methacrylic. The term "(meth)acryloyl" refers to acryloyl and methacryloyl.

The resin particles can be obtained by polymerizing the polymerizable monomer having an ethylenically unsaturated group by a known method. Examples of this method include a method in which suspension polymerization is carried out in the presence of a radical polymerization initiator, and a method in which monomers are swollen and polymerized together with a radical polymerization initiator using non-crosslinked seed particles.

When the base particles are inorganic particles excluding metals or organic-inorganic hybrid particles, examples of the inorganic substance for forming the base particles include silica, alumina, barium titanate, zirconia, and carbon black. Preferably, the inorganic substance is not a metal. The particles formed from the silica are not particularly limited, but for example, after hydrolyzing a silicon compound having two or more hydrolyzable alkoxysilyl groups to form crosslinked polymer particles, baking may be performed as necessary. Examples include particles obtained by Examples of the organic-inorganic hybrid particles include organic-inorganic hybrid particles formed from a crosslinked alkoxysilyl polymer and an acrylic resin.

The organic-inorganic hybrid particles are preferably core-shell type organic-inorganic hybrid particles having a core and a shell disposed on the surface of the core. Preferably, the core is an organic core. Preferably, the shell is an inorganic shell. From the viewpoint of effectively lowering the connection resistance between electrodes, the base particles are preferably organic-inorganic hybrid particles having an organic core and an inorganic shell disposed on the surface of the organic core.

Examples of the material for the organic core include the materials for the resin particles described above.

Examples of the material for the inorganic shell include the inorganic substances mentioned above as the material for the base particle. The material of the inorganic shell is preferably silica. The inorganic shell is preferably formed by forming a metal alkoxide into a shell-like material by a sol-gel method on the surface of the core, and then firing the shell-like material. Preferably, the metal alkoxide is a silane alkoxide. The inorganic shell is preferably formed of silane alkoxide.

When the base particles are metal particles, examples of the metal that is the material of the metal particles include silver, copper, nickel, silicon, gold, tin, and titanium. Further, the metal particles may be the solder particles described above.

The particle diameter of the base particles is preferably 0.5 μm or more, more preferably 1 μm or more, even more preferably 3 μm or more, and preferably 100 μm or less, more preferably 60 μm or less, and still more preferably 50 μm or less. When the particle diameter of the base material particles is not less than the above lower limit and not more than the above upper limit, the solder can be disposed on the electrode even more efficiently. Furthermore, when forming a conductive part on the surface of the base material particles, it becomes difficult to aggregate, and it becomes difficult to form aggregated conductive particles X.

It is particularly preferable that the particle diameter of the base material particles is 5 μm or more and 40 μm or less. When the particle diameter of the base particles is within the range of 5 μm or more and 40 μm or less, the solder can be placed on the electrode even more efficiently.

The particle diameter of the base material particle indicates the diameter when the base material particle is true spherical, and indicates the maximum diameter when the base material particle is not true spherical.

The particle diameter of the base material particles indicates the number average particle diameter. The particle diameter of the base material particles is determined using a particle size distribution measuring device or the like. The particle diameter of the base particles is preferably determined by observing 50 base particles using an electron microscope or an optical microscope and calculating the average value. In observation using an electron microscope or an optical microscope, the particle diameter of each base particle is determined as the particle diameter in equivalent circle diameter. In observation using an electron microscope or an optical microscope, the average particle diameter of any 50 base particles in equivalent circle diameter is approximately equal to the average particle diameter in equivalent sphere diameter. In the particle size distribution measuring device, the particle diameter of each base material particle is determined as the particle diameter in equivalent sphere diameter. The particle diameter of the base material particles is preferably calculated using a particle size distribution measuring device. In the conductive particles X, when measuring the particle diameter of the base particles, it can be measured, for example, as follows.

The conductive particles X are added to "Technovit 4000" manufactured by Kulzer so that the content thereof becomes 30% by weight, and dispersed to prepare an embedding resin for conductive particle X inspection. Using an ion milling device (“IM4000” manufactured by Hitachi High-Technologies), a cross section of the conductive particles X is cut out so as to pass near the center of the conductive particles X dispersed in the embedding resin for inspection. Then, using a field emission scanning electron microscope (FE-SEM), the image magnification was set to 25,000 times, 50 conductive particles X were randomly selected, and the base material particles of each conductive particle Observe. The particle size of the base material particles in each conductive particle X is measured, and the arithmetic average of these is determined as the particle size of the base material particle.

(conductive part)
The method of forming the conductive part on the surface of the base particle and the method of forming the first conductive part on the surface of the base particle or the surface of the second conductive part are not particularly limited. Examples of the method for forming the conductive part include electroless plating, electroplating, physical collision, mechanochemical reaction, physical vapor deposition or physical adsorption, and metal powder or Examples include a method of coating the surface of base particles with a paste containing metal powder and a binder. The method for forming the conductive portion is preferably electroless plating, electroplating, or physical collision. Examples of the physical vapor deposition method include vacuum vapor deposition, ion plating, and ion sputtering. Further, in the method using physical collision, for example, a sheeter composer (manufactured by Tokuju Kosho Co., Ltd.) or the like is used.

The melting point of the base particles is preferably higher than the melting point of the conductive part. The melting point of the base particles is preferably higher than 160°C, more preferably higher than 300°C, even more preferably higher than 400°C, particularly preferably higher than 450°C. Note that the melting point of the base particles may be lower than 400°C. The melting point of the base particles may be 160°C or lower. The softening point of the base particles is preferably 260°C or higher. The softening point of the base particles may be less than 260°C.

Preferably, the conductive part includes metal. The metal constituting the conductive part is not particularly limited. Examples of the metal include gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, cadmium, and alloys thereof. Moreover, tin-doped indium oxide (ITO) or solder may be used as the metal. The above metals may be used alone or in combination of two or more.

The conductive particles X may have a single layer solder portion. The conductive particles X may have a single-layer conductive part, or may have a plurality of layers of conductive parts (a first conductive part and a second conductive part). That is, in the conductive particles X, two or more layers of conductive parts may be laminated. When the conductive part has two or more layers, the conductive particles X may have solder on the outer surface of the conductive part.

Preferably, the solder has the same composition as the solder particles described above.

The low melting point metal constituting the solder is not particularly limited. The low melting point metal is preferably a low melting point metal that constitutes the solder particles described above.

The melting point of the second conductive part is preferably higher than the melting point of the first conductive part. The melting point of the second conductive part is preferably higher than 160°C, more preferably higher than 300°C, still more preferably higher than 400°C, even more preferably higher than 450°C, particularly preferably higher than 500°C, Most preferably above 600°C. Since the first conductive part has a low melting point, it melts during conductive connection. Preferably, the second conductive portion does not melt during conductive connection. The first conductive part is preferably a solder part, preferably used by melting the first conductive part, and by melting the first conductive part and soldering the second conductive part. It is preferable to use it without melting it. Since the melting point of the second conductive part is higher than the melting point of the first conductive part, only the first conductive part is melted without melting the second conductive part during conductive connection. be able to.

The absolute value of the difference between the melting point of the first conductive part and the melting point of the second conductive part exceeds 0°C, preferably 5°C or more, more preferably 10°C or more, and even more preferably 30°C or more. , particularly preferably 50°C or higher, most preferably 100°C or higher.

Preferably, the second conductive portion includes metal. The metal constituting the second conductive part is not particularly limited. Examples of the metal include gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium, cadmium, and alloys thereof. Furthermore, tin-doped indium oxide (ITO) may be used as the metal. The above metals may be used alone or in combination of two or more.

The second conductive part is preferably a nickel layer, a palladium layer, a copper layer, or a gold layer, more preferably a nickel layer, a gold layer, or a copper layer, and even more preferably a copper layer. The conductive particles X preferably have a nickel layer, a palladium layer, a copper layer, or a gold layer, more preferably a nickel layer, a gold layer, or a copper layer, and even more preferably a copper layer. By using the conductive particles X having these preferable conductive parts for connection between electrodes, it is possible to arrange the solder between the electrodes even more efficiently.

The thickness of the first conductive portion is preferably 0.005 μm or more, more preferably 0.01 μm or more, and preferably 10 μm or less, more preferably 1 μm or less, and still more preferably 0.3 μm or less. When the thickness of the first conductive part is not less than the above lower limit and not more than the above upper limit, the solder can be placed on the electrode even more efficiently, and the continuity reliability and connection reliability are further effectively increased. be able to.

The particle diameter of the conductive particles X is preferably 2 μm or more, more preferably 5 μm or more, and preferably 35 μm or less, more preferably 20 μm or less. When the particle diameter of the conductive particles can be increased. It is particularly preferable that the particle diameter of the conductive particles X is 15 μm or less. When the particle diameter of the conductive particles X is 15 μm or less, the solder can be disposed on the electrode more efficiently, and the conduction reliability and connection reliability can be further effectively increased.

The particle diameter of the conductive particles X is preferably an average particle diameter, and more preferably a number average particle diameter. The average particle diameter of the conductive particles . In observation using an electron microscope or an optical microscope, the particle diameter of each conductive particle X is determined as a particle diameter in equivalent circle diameter. In observation using an electron microscope or an optical microscope, the average particle diameter of any 50 conductive particles X in equivalent circle diameter is approximately equal to the average particle diameter in equivalent sphere diameter. In the laser diffraction particle size distribution measurement, the particle diameter of each conductive particle X is determined as the particle diameter in equivalent sphere diameter. The particle diameter of the conductive particles X is preferably calculated by laser diffraction particle size distribution measurement.

The CV value of the particle diameter of the conductive particles X is preferably 5% or more, more preferably 10% or more, and preferably 40% or less, more preferably 30% or less. When the CV value of the particle size is not less than the lower limit and not more than the upper limit, the solder can be disposed on the electrode even more efficiently. However, the CV value of the particle diameter of the conductive particles X may be less than 5%.

The CV value (coefficient of variation) of the particle diameter of the conductive particles X can be measured as follows.

CV value (%) = (ρ/Dn) x 100
ρ: Standard deviation of particle diameter of conductive particles X Dn: Average value of particle diameter of conductive particles X

The shape of the conductive particles X is not particularly limited. The conductive particles X may have a spherical shape, a shape other than a spherical shape, a flat shape, or the like.

The content of the conductive particles X in 100% by weight of the conductive material is preferably 40% by weight or more, more preferably 45% by weight or more, still more preferably 55% by weight or more, particularly preferably 60% by weight or more. , preferably 90% by weight or less, more preferably 85% by weight or less, still more preferably 80% by weight or less. When the content of the conductive particles , it is possible to further effectively improve conduction reliability and connection reliability.

(thermosetting component)
The conductive material includes a thermosetting component. The electrically conductive material may include a thermosetting compound and a thermosetting agent as thermosetting components. In order to cure the conductive material even better, the conductive material preferably contains a thermosetting compound and a thermosetting agent as thermosetting components. In order to cure the conductive material even better, the conductive material preferably contains a curing accelerator as a thermosetting component.

(Thermosetting component: thermosetting compound)
The above thermosetting compound is not particularly limited. Examples of the thermosetting compound include oxetane compounds, epoxy compounds, episulfide compounds, (meth)acrylic compounds, phenol compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds, and polyimide compounds. From the viewpoint of further improving the curability and viscosity of the conductive material, from the viewpoint of further effectively increasing the conduction reliability, and from the viewpoint of further effectively increasing the insulation reliability, the above thermosetting compounds include: Epoxy compounds or episulfide compounds are preferred, and epoxy compounds are more preferred. The thermosetting compound preferably includes an epoxy compound. The above thermosetting compounds may be used alone or in combination of two or more.

The above epoxy compound is a compound having at least one epoxy group. The above-mentioned epoxy compounds include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol S type epoxy compounds, phenol novolak type epoxy compounds, biphenyl type epoxy compounds, biphenyl novolac type epoxy compounds, biphenol type epoxy compounds, and naphthalene type epoxy compounds. , fluorene type epoxy compound, phenol aralkyl type epoxy compound, naphthol aralkyl type epoxy compound, dicyclopentadiene type epoxy compound, anthracene type epoxy compound, epoxy compound having an adamantane skeleton, epoxy compound having a tricyclodecane skeleton, naphthylene ether type Examples include epoxy compounds and epoxy compounds having a triazine nucleus in their skeleton. Only one kind of the above-mentioned epoxy compound may be used, or two or more kinds thereof may be used in combination.

The epoxy compound is liquid or solid at room temperature (23° C.), and when the epoxy compound is solid at room temperature, the melting temperature of the epoxy compound is preferably equal to or lower than the melting point of the solder. By using the preferred epoxy compound described above, the viscosity is high at the stage when the connection target members are bonded together, and when acceleration is applied due to impact such as transportation, the first connection target member and the second connection target member are bonded together. Misalignment with the target member can be suppressed. Furthermore, the heat generated during curing can greatly reduce the viscosity of the conductive material, allowing the solder to coagulate efficiently.

From the viewpoint of further effectively increasing the insulation reliability and the viewpoint of further effectively increasing the conduction reliability, the thermosetting compound preferably contains an epoxy compound.

From the viewpoint of disposing the solder on the electrode more efficiently, the thermosetting compound preferably includes a thermosetting compound having a polyether skeleton.

Examples of the thermosetting compound having a polyether skeleton include a compound having a glycidyl ether group at both ends of an alkyl chain having 3 to 12 carbon atoms, and a compound having a polyether skeleton having 2 to 4 carbon atoms; Examples include polyether-type epoxy compounds having 2 to 10 consecutively bonded structural units.

From the viewpoint of further effectively increasing the heat resistance of the cured product, the thermosetting compound preferably contains a thermosetting compound having an isocyanuric skeleton.

Examples of the thermosetting compound having an isocyanuric skeleton include triisocyanurate type epoxy compounds, which include the TEPIC series manufactured by Nissan Chemical Industries, Ltd. (TEPIC-G, TEPIC-S, TEPIC-SS, TEPIC-HP, TEPIC-L, TEPIC-PAS, TEPIC-VL, TEPIC-UC), etc.

The content of the thermosetting compound in 100% by weight of the conductive material is preferably 5% by weight or more, more preferably 10% by weight or more, even more preferably 15% by weight or more, and preferably 90% by weight or less, more preferably The content is preferably 70% by weight or less, more preferably 50% by weight or less, particularly preferably 30% by weight or less. When the content of the thermosetting compound is at least the above lower limit and below the above upper limit, the solder can be placed on the electrodes even more efficiently, and the insulation reliability between the electrodes can be further effectively improved. , it is possible to further effectively improve the reliability of conduction between the electrodes. From the viewpoint of increasing impact resistance even more effectively, it is preferable that the content of the thermosetting compound is as large as possible.

The content of the epoxy compound in 100% by weight of the conductive material is preferably 5% by weight or more, more preferably 10% by weight or more, even more preferably 15% by weight or more, and preferably 90% by weight or less, more preferably It is 70% by weight or less, more preferably 50% by weight or less, particularly preferably 30% by weight or less. When the content of the epoxy compound is not less than the lower limit and not more than the upper limit, the solder can be placed on the electrode more efficiently, and the insulation reliability between the electrodes can be further effectively increased. The reliability of conduction between the two can be further effectively improved. From the viewpoint of further improving impact resistance, it is preferable that the content of the epoxy compound is as large as possible.

(Thermosetting component: thermosetting agent)
The above thermosetting agent is not particularly limited. The thermosetting agent thermosets the thermosetting compound. Examples of the above-mentioned thermosetting agents include thiol curing agents such as imidazole curing agents, amine curing agents, phenol curing agents, and polythiol curing agents, acid anhydride curing agents, thermal cationic initiators (thermal cationic curing agents), thermal radical generators, etc. can be mentioned. The above thermosetting agents may be used alone or in combination of two or more.

From the viewpoint of enabling the conductive material to be cured more rapidly at low temperatures, the thermosetting agent is preferably an imidazole curing agent, a thiol curing agent, or an amine curing agent. Further, from the viewpoint of improving the storage stability when the thermosetting compound and the thermosetting agent are mixed, the thermosetting agent is preferably a latent curing agent. Preferably, the latent curing agent is a latent imidazole curing agent, a latent thiol curing agent or a latent amine curing agent. Note that the thermosetting agent may be coated with a polymeric substance such as polyurethane resin or polyester resin.

The above imidazole curing agent is not particularly limited. Examples of the imidazole curing agent include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6 -[2'-Methylimidazolyl-(1')]-ethyl-s-triazine and 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct , 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4-benzyl-5-hydroxymethylimidazole, 2-paratolyl-4-methyl-5 -5-position of 1H-imidazole in hydroxymethylimidazole, 2-metatolyl-4-methyl-5-hydroxymethylimidazole, 2-metatolyl-4,5-dihydroxymethylimidazole, 2-paratolyl-4,5-dihydroxymethylimidazole, etc. Examples include imidazole compounds in which hydrogen at the 2-position is substituted with a hydroxymethyl group and hydrogen at the 2-position is substituted with a phenyl group or a tolyl group.

The above-mentioned thiol curing agent is not particularly limited. Examples of the thiol curing agent include trimethylolpropane tris-3-mercaptopropionate, pentaerythritol tetrakis-3-mercaptopropionate, and dipentaerythritol hexa-3-mercaptopropionate.

The above amine curing agent is not particularly limited. Examples of the amine curing agent include hexamethylene diamine, octamethylene diamine, decamethylene diamine, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraspiro[5.5]undecane, bis(4 -aminocyclohexyl)methane, metaphenylenediamine, and diaminodiphenylsulfone.

The acid anhydride curing agent is not particularly limited, and any acid anhydride that can be used as a curing agent for thermosetting compounds such as epoxy compounds can be used. The acid anhydride curing agents include phthalic anhydride, tetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylbutenyltetrahydrophthalic anhydride. , anhydrides of phthalic acid derivatives, maleic anhydride, nadic anhydride, methyl nadic anhydride, glutaric anhydride, succinic anhydride, glycerin bis-trimellitic anhydride monoacetate, and difunctional compounds such as ethylene glycol bis-trimellitic anhydride. trifunctional acid anhydride curing agents such as trimellitic anhydride, pyromellitic anhydride, benzophenonetetracarboxylic anhydride, methylcyclohexenetetracarboxylic anhydride, polyazelaic anhydride, etc. Examples include acid anhydride curing agents having four or more functional groups.

The thermal cationic initiator is not particularly limited. Examples of the thermal cationic initiator include iodonium-based cationic curing agents, oxonium-based cationic curing agents, and sulfonium-based cationic curing agents. Examples of the iodonium-based cationic curing agent include bis(4-tert-butylphenyl)iodonium hexafluorophosphate. Examples of the oxonium-based cationic curing agent include trimethyloxonium tetrafluoroborate. Examples of the sulfonium-based cationic curing agent include tri-p-tolylsulfonium hexafluorophosphate.

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

The reaction initiation temperature of the thermosetting agent is preferably 50°C or higher, more preferably 70°C or higher, even more preferably 80°C or higher, preferably 250°C or lower, more preferably 200°C or lower, and even more preferably 150°C. The temperature below is particularly preferably 140°C or below. When the reaction start temperature of the thermosetting agent is equal to or higher than the lower limit and lower than the upper limit, the solder can be disposed on the electrode more efficiently. It is particularly preferable that the reaction initiation temperature of the thermosetting agent is 80°C or more and 140°C or less.

From the viewpoint of disposing the solder on the electrode more efficiently, the reaction initiation temperature of the thermosetting agent is preferably higher than the melting point of the solder particles, more preferably 5°C or more higher, and 10°C or more. It is more preferable that it is higher than that.

The reaction start temperature of the thermosetting agent means the temperature at which the exothermic peak starts rising in DSC.

The content of the thermosetting agent is not particularly limited. The content of the thermosetting agent is preferably 0.01 parts by weight or more, more preferably 1 part by weight or more, and preferably 200 parts by weight or less, more preferably 200 parts by weight or less, based on 100 parts by weight of the thermosetting compound. The amount is 100 parts by weight or less, more preferably 75 parts by weight or less. When the content of the thermosetting agent is at least the above lower limit, it is easy to sufficiently cure the conductive material. When the content of the thermosetting agent is below the above upper limit, it becomes difficult for excess thermosetting agent that did not take part in curing to remain after curing, and the heat resistance of the cured product becomes even higher.

(Thermosetting component: curing accelerator)
The conductive material may contain a curing accelerator. The above-mentioned curing accelerator is not particularly limited. The curing accelerator preferably acts as a curing catalyst in the reaction between the thermosetting compound and the thermosetting agent. The curing accelerator preferably acts as a curing catalyst in the reaction with the thermosetting compound. As for the said hardening accelerator, only 1 type may be used, and 2 or more types may be used together.

Examples of the curing accelerator include phosphonium salts, tertiary amines, tertiary amine salts, quaternary onium salts, tertiary phosphines, crown ether complexes, and phosphonium ylides. Specifically, the curing accelerators include imidazole compounds, isocyanurates of imidazole compounds, dicyandiamide, derivatives of dicyandiamide, melamine compounds, derivatives of melamine compounds, diaminomaleonitrile, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine. , bis(hexamethylene)triamine, triethanolamine, diaminodiphenylmethane, amine compounds such as organic acid dihydrazide, 1,8-diazabicyclo[5,4,0]undecene-7,3,9-bis(3-aminopropyl) -2,4,8,10-tetraoxaspiro[5,5]undecane, boron trifluoride, and organic phosphorus compounds such as triphenylphosphine, tricyclohexylphosphine, tributylphosphine, and methyldiphenylphosphine.

The above phosphonium salt is not particularly limited. Examples of the phosphonium salts include tetra-n-butylphosphonium bromide, tetra-n-butylphosphonium O,O-diethyldithiophosphate, methyltributylphosphonium dimethyl phosphate, tetra-n-butylphosphonium benzotriazole, tetra-n-butylphosphonium tetrafluoroborate, and tetra-n-butylphosphonium tetrafluoroborate. Examples include butylphosphonium tetraphenylborate.

The content of the curing accelerator is appropriately selected so that the thermosetting compound is well cured. The content of the curing accelerator relative to 100 parts by weight of the thermosetting compound is preferably 0.5 parts by weight or more, more preferably 0.8 parts by weight or more, and preferably 10 parts by weight or less, more preferably 8 parts by weight. Parts by weight or less. When the content of the curing accelerator is at least the above lower limit and at most the above upper limit, the thermosetting compound can be cured well.

(flux)
The conductive material includes flux. By using flux, solder can be placed on the electrodes more efficiently. The above flux is not particularly limited. As the above-mentioned flux, a flux commonly used for soldering and the like can be used.

The above fluxes include zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, a molten salt, phosphoric acid, a derivative of phosphoric acid, an organic halide, hydrazine, an amine compound, an organic acid and Examples include pine resin. The above fluxes may be used alone or in combination of two or more.

Examples of the molten salt include ammonium chloride. Examples of the organic acids include lactic acid, citric acid, stearic acid, glutamic acid, and glutaric acid. Examples of the pine resin include activated pine resin and non-activated pine resin. The flux is preferably an organic acid having two or more carboxyl groups or pine resin. The above-mentioned flux may be an organic acid having two or more carboxyl groups, or may be pine resin. By using an organic acid having two or more carboxyl groups or pine resin, the reliability of conduction between the electrodes is further increased.

Examples of the organic acids having two or more carboxyl groups include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

Examples of the amine compounds include cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, imidazole, benzimidazole, phenylimidazole, carboxybenzimidazole, benzotriazole, and carboxybenzotriazole.

The above-mentioned pine resin is a rosin whose main component is abietic acid. Examples of the rosins include abietic acid and acrylic modified rosin. The flux is preferably a rosin, more preferably abietic acid. By using this preferable flux, the reliability of conduction between the electrodes is further increased.

Preferably, the flux is liquid at 23°C. Since the above-mentioned flux is liquid at 23°C, the diffusion coefficient showing the above-mentioned maximum value can be more easily adjusted to the above-mentioned preferable range, and the solder can be disposed on the electrode more efficiently. .

The flux that is liquid at 23° C. is not particularly limited. The flux that is liquid at 23° C. is preferably an acidic phosphate ester compound. Commercially available products of the acidic phosphate ester compound include ethyl acid phosphate and butyl acid phosphate (both manufactured by Johoku Kagaku Kogyo Co., Ltd.).

The activation temperature (melting point) of the above flux is preferably -20°C or higher, more preferably 0°C or higher, and preferably 120°C or lower, more preferably 60°C or lower. When the active temperature (melting point) of the flux is at least the above lower limit and below the above upper limit, the flux effect is even more effectively exhibited, and the solder is more efficiently disposed on the electrode.

Moreover, it is preferable that the boiling point of the above-mentioned flux is 200° C. or lower.

The flux may be dispersed in the conductive material or may be attached to the surface of the conductive particles.

From the viewpoint of arranging the solder more efficiently on the electrode, from the viewpoint of further effectively increasing the insulation reliability, and from the viewpoint of further effectively increasing the continuity reliability, the above-mentioned flux is composed of an acid compound and a basic compound. It is preferable that it is a salt with.

The acid compound is preferably an organic compound having a carboxyl group. The above acid compounds include aliphatic carboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, citric acid, malic acid, and cycloaliphatic carboxylic acids. Examples include cyclohexylcarboxylic acid, 1,4-cyclohexyldicarboxylic acid, aromatic carboxylic acids such as isophthalic acid, terephthalic acid, trimellitic acid, and ethylenediaminetetraacetic acid. From the viewpoint of arranging the solder more efficiently on the electrode, from the viewpoint of further effectively increasing the insulation reliability, and from the viewpoint of further effectively increasing the conduction reliability, the above acid compounds include glutaric acid, cyclohexyl Preferably, it is carboxylic acid or adipic acid.

The basic compound is preferably an organic compound having an amino group. The above basic compounds include diethanolamine, triethanolamine, methyldiethanolamine, ethyldiethanolamine, cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, 2-methylbenzylamine, 3-methylbenzylamine, 4-tert-butylbenzylamine. , N-methylbenzylamine, N-ethylbenzylamine, N-phenylbenzylamine, N-tert-butylbenzylamine, N-isopropylbenzylamine, N,N-dimethylbenzylamine, imidazole compounds, and triazole compounds. . From the viewpoint of arranging the solder on the electrode more efficiently, from the viewpoint of further effectively increasing insulation reliability, and from the viewpoint of further effectively increasing continuity reliability, the above basic compound is benzylamine. It is preferable.

The content of the flux in 100% by weight of the conductive material is preferably 0.5% by weight or more, preferably 30% by weight or less, and more preferably 25% by weight or less. The above-mentioned conductive material does not need to contain flux. When the content of the flux is above the above lower limit and below the above upper limit, it becomes even more difficult to form an oxide film on the surfaces of the solder and the electrodes, and furthermore, the oxide film formed on the surfaces of the solder and the electrodes becomes even more difficult to form. Can be removed effectively.

(filler)
The conductive material according to the present invention may contain a filler. The filler may be an organic filler or an inorganic filler. Since the conductive material contains a filler, the solder can be uniformly aggregated on all the electrodes of the substrate.

It is preferable that the conductive material does not contain the filler or contains 5% by weight or less of the filler. When using the above-mentioned thermosetting compound, the smaller the filler content, the easier the solder will move onto the electrode.

The content of the filler in 100% by weight of the conductive material is preferably 0% by weight or more (not contained), preferably 5% by weight or less, more preferably 2% by weight or less, and even more preferably 1% by weight or less. be. When the content of the filler is not less than the lower limit and not more than the upper limit, the solder is more uniformly disposed on the electrode.

(other ingredients)
The above-mentioned conductive material may contain, if necessary, a filler, an extender, a softener, a plasticizer, a thixotropic agent, a leveling agent, a polymerization catalyst, a curing catalyst, a coloring agent, an antioxidant, a heat stabilizer, and a light stabilizer. , an ultraviolet absorber, a lubricant, an antistatic agent, a flame retardant, and other various additives.

(Connected structure and method for manufacturing the connected structure)
The connection structure according to the present invention includes a first connection target member having a first electrode on its surface, a second connection target member having a second electrode on its surface, and the first connection target member, and a connecting portion connecting the second connection target member. In the connected structure according to the present invention, the material of the connecting portion is the conductive material described above. In the connected structure according to the present invention, the first electrode and the second electrode are electrically connected by a solder part in the connecting part.

A method for manufacturing a connected structure according to the present invention uses a conductive material containing a thermosetting component, a flux, and conductive particles containing solder to produce a first connection target member having a first electrode on its surface. a first step of disposing the conductive material on the surface of the conductive material. The method for manufacturing a connected structure according to the present invention includes a method for manufacturing a connected structure, in which a second connection target member having a second electrode on the surface is placed on a surface of the conductive material opposite to the first connection target member side. The method includes a second step of arranging the first electrode and the second electrode to face each other. The method for manufacturing a connected structure according to the present invention connects the first connection target member and the second connection target member by heating the conductive material above the melting point of the conductive particles. A third step is provided in which a connecting portion is formed of the conductive material, and the first electrode and the second electrode are electrically connected by a solder portion in the connecting portion. In the method for manufacturing a connected structure according to the present invention, the following first electrode surface material and conductive material are used as a combination of the first electrode surface material and the conductive material. When the conductive material is coated on a substrate whose surface material is the same as that of the first electrode and heated to 70°C, the amount of metal contained in the conductive particles calculated by EPMA analysis is A material and a conductive material for the surface of the first electrode whose maximum diffusion coefficient is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less .

Since the method for manufacturing a connected structure according to the present invention includes the above-mentioned configuration, solder can be efficiently placed on the electrodes.

In the above method for manufacturing a connected structure, it is preferable to use the following second electrode surface material and conductive material as a combination of the second electrode surface material and the conductive material. When the conductive material is coated on a substrate whose surface material is the same as that of the second electrode and heated to 70°C, the amount of metal contained in the conductive particles calculated by EPMA analysis is A material and a conductive material for the surface of the second electrode whose maximum value among the diffusion coefficients is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less . When the surface material and the conductive material of the second electrode satisfy the above-mentioned preferred embodiments, the solder can be placed on the electrode even more efficiently.

From the viewpoint of disposing the solder on the electrodes more efficiently, the first electrode and the second electrode are preferably gold electrodes, silver electrodes, copper electrodes, or aluminum electrodes. More preferably, it is an electrode.

In the bonded structure and the method for manufacturing the bonded structure according to the present invention, since a specific conductive material is used, the solder tends to collect between the first electrode and the second electrode, and the solder is connected to the electrode (line). can be efficiently placed on top. In addition, a portion of the solder is less likely to be placed in the area (space) where no electrode is formed, and the amount of solder placed in the area where no electrode is formed can be considerably reduced. Therefore, the reliability of conduction between the first electrode and the second electrode can be improved. Moreover, electrical connection between horizontally adjacent electrodes that should not be connected can be prevented, and insulation reliability can be improved.

In addition, in order to efficiently arrange the solder on the electrodes and to significantly reduce the amount of solder placed in areas where no electrodes are formed, the above-mentioned conductive material should be a conductive paste instead of a conductive film. It is preferable.

The thickness of the solder portion between the electrodes is preferably 10 μm or more, more preferably 20 μm or more, and preferably 100 μm or less, more preferably 80 μm or less. The solder wetted area on the surface of the electrode (the area in contact with the solder out of 100% of the exposed area of the electrode) is preferably 50% or more, more preferably 70% or more, and preferably 100% or less.

In the method for manufacturing a connected structure according to the present invention, in the step of arranging the second connection target member and the step of forming the connection part, no pressure is applied to the conductive material, and the second connection target member is not pressurized. Preferably, the weight of the target member is added. In the method for manufacturing a connected structure according to the present invention, in the step of arranging the second member to be connected and the step of forming the connecting portion, the conductive material is subjected to the force of the weight of the second member to be connected. It is preferable not to apply pressure exceeding . In these cases, the uniformity of the amount of solder can be further improved in the plurality of solder parts. Furthermore, the thickness of the solder portion can be increased more effectively, and more solder tends to collect between the electrodes, so that the solder can be more efficiently placed on the electrodes (lines). Further, a portion of the solder is less likely to be placed in a region (space) where no electrode is formed, and the amount of solder placed in a region where no electrode is formed can be further reduced. Therefore, the reliability of conduction between the electrodes can be further improved. Moreover, electrical connections between horizontally adjacent electrodes that should not be connected can be further prevented, and insulation reliability can be further improved.

Further, if a conductive paste is used instead of a conductive film, it becomes easy to adjust the thickness of the connection portion and the solder portion by adjusting the amount of conductive paste applied. On the other hand, with conductive films, there is a problem in that in order to change or adjust the thickness of the connection part, it is necessary to prepare conductive films of different thicknesses or to prepare conductive films of a predetermined thickness. There is. In addition, in a conductive film, compared to a conductive paste, the melt viscosity of the conductive film cannot be sufficiently lowered at the melting temperature of the solder, and the aggregation of the solder tends to be inhibited.

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

FIG. 1 is a cross-sectional view schematically showing a connected structure obtained using a conductive material according to an embodiment of the present invention.

The connection structure 1 shown in FIG. 1 includes a first connection target member 2, a second connection target member 3, and a connection connecting the first connection target member 2 and the second connection target member 3. 4. The connecting portion 4 is made of the above-mentioned conductive material. In this embodiment, the conductive material includes a thermosetting component, a flux, and conductive particles containing solder. The thermosetting component includes a thermosetting compound and a thermosetting agent. The conductive particles are solder particles. In this embodiment, a conductive paste is used as the conductive material.

The connecting portion 4 includes a solder portion 4A in which a plurality of solder particles are gathered and bonded to each other, and a cured material portion 4B in which a thermosetting compound is thermoset.

The first connection target member 2 has a plurality of first electrodes 2a on its surface (upper surface). The second connection target member 3 has a plurality of second electrodes 3a on the front surface (lower surface). The first electrode 2a and the second electrode 3a are electrically connected by a solder portion 4A. Therefore, the first connection target member 2 and the second connection target member 3 are electrically connected by the solder portion 4A. Note that, in the connecting portion 4, no solder particles exist in a region different from the solder portion 4A gathered between the first electrode 2a and the second electrode 3a (cured material portion 4B portion). In a region different from the solder portion 4A (cured material portion 4B portion), there are no solder particles separate from the solder portion 4A. Note that solder particles may be present in a region different from the solder portion 4A gathered between the first electrode 2a and the second electrode 3a (cured material portion 4B portion) as long as the amount is small.

As shown in FIG. 1, in the connection structure 1, a plurality of solder particles gather between a first electrode 2a and a second electrode 3a, and after the plurality of solder particles are melted, a melted solder particle is formed. The solder portion 4A is formed by wetting and spreading the surface of the electrode and solidifying the solder portion 4A. Therefore, the connection area between the solder portion 4A and the first electrode 2a and between the solder portion 4A and the second electrode 3a becomes large. That is, by using solder particles, the solder part 4A, the first electrode 2a, and the solder part The contact area between 4A and the second electrode 3a becomes larger. This also increases the conduction reliability and connection reliability in the connection structure 1. Note that when the conductive material contains flux, the flux is generally gradually deactivated by heating.

In addition, in the connection structure 1 shown in FIG. 1, all of the solder parts 4A are located in the opposing region between the first and second electrodes 2a and 3a. The modified connected structure 1X shown in FIG. 3 differs from the connected structure 1 shown in FIG. 1 only in the connecting portion 4X. The connecting portion 4X has a solder portion 4XA and a cured material portion 4XB. Like the connection structure 1X, most of the solder portion 4XA is located in the area where the first and second electrodes 2a and 3a are facing each other, and a part of the solder portion 4XA is located in the area where the first and second electrodes 2a and 3a face each other. It may protrude laterally from the opposing regions of the electrodes 2a and 3a. The solder portion 4XA that protrudes laterally from the opposing region of the first and second electrodes 2a and 3a is a part of the solder portion 4XA, and is not a solder particle separated from the solder portion 4XA. In addition, in this embodiment, the amount of solder particles separated from the solder part can be reduced, but the solder particles separated from the solder part may exist in the cured material part.

By reducing the amount of solder particles used, it becomes easier to obtain the connected structure 1. If the amount of solder particles used is increased, it becomes easier to obtain the connected structure 1X.

In the connection structures 1 and 1X, when looking at the opposing portions of the first electrode 2a and the second electrode 3a in the stacking direction of the first electrode 2a, the connection parts 4 and 4X, and the second electrode 3a Preferably, the solder portions 4A and 4XA in the connecting portions 4 and 4X are arranged in 50% or more of the 100% area of the opposing portions of the first electrode 2a and the second electrode 3a. . When the solder portions 4A and 4XA in the connection portions 4 and 4X satisfy the above-mentioned preferred embodiments, the continuity reliability can be further improved.

When looking at the opposing portions of the first electrode and the second electrode in the stacking direction of the first electrode, the connecting portion, and the second electrode, the first electrode and the second electrode It is preferable that the solder portion in the connection portion is disposed on 50% or more of the 100% area of the portion facing the second electrode. When looking at the opposing portions of the first electrode and the second electrode in the stacking direction of the first electrode, the connecting portion, and the second electrode, the first electrode and the second electrode It is more preferable that the solder portion in the connection portion is disposed on 60% or more of the 100% area of the portion facing the second electrode. When looking at the opposing portions of the first electrode and the second electrode in the stacking direction of the first electrode, the connecting portion, and the second electrode, the first electrode and the second electrode It is more preferable that the solder part in the connection part is disposed on 70% or more of the 100% area of the part facing the second electrode. When looking at the opposing portions of the first electrode and the second electrode in the stacking direction of the first electrode, the connecting portion, and the second electrode, the first electrode and the second electrode It is particularly preferable that the solder portion in the connection portion is disposed on 80% or more of the 100% area of the portion facing the second electrode. When looking at the opposing portions of the first electrode and the second electrode in the stacking direction of the first electrode, the connecting portion, and the second electrode, the first electrode and the second electrode It is most preferable that the solder part in the connection part is disposed on 90% or more of the 100% area of the part facing the second electrode. When the solder portion in the connection portion satisfies the preferred embodiments described above, conduction reliability can be further improved.

When the opposing portions of the first electrode and the second electrode are viewed in a direction perpendicular to the stacking direction of the first electrode, the connection portion, and the second electrode, the first It is preferable that 60% or more of the solder portion in the connection portion is disposed at the portion where the electrode and the second electrode face each other. When the opposing portions of the first electrode and the second electrode are viewed in a direction perpendicular to the stacking direction of the first electrode, the connection portion, and the second electrode, the first More preferably, 70% or more of the solder portion in the connection portion is disposed in a portion where the electrode and the second electrode face each other. When the opposing portions of the first electrode and the second electrode are viewed in a direction perpendicular to the stacking direction of the first electrode, the connection portion, and the second electrode, the first It is further preferable that 90% or more of the solder portion in the connection portion be disposed at a portion where the electrode and the second electrode face each other. When the opposing portions of the first electrode and the second electrode are viewed in a direction perpendicular to the stacking direction of the first electrode, the connection portion, and the second electrode, the first It is particularly preferable that 95% or more of the solder portion in the connection portion is disposed at the portion where the electrode and the second electrode face each other. When the opposing portions of the first electrode and the second electrode are viewed in a direction perpendicular to the stacking direction of the first electrode, the connection portion, and the second electrode, the first It is most preferable that 99% or more of the solder portion in the connecting portion is disposed at the portion where the electrode and the second electrode face each other. When the solder portion in the connection portion satisfies the preferred embodiments described above, conduction reliability can be further improved.

Next, in FIG. 2, an example of a method for manufacturing the connected structure 1 using a conductive material according to an embodiment of the present invention will be described.

First, a first connection target member 2 having a first electrode 2a on its surface (upper surface) is prepared. Next, as shown in FIG. 2(a), a conductive material 11 containing a thermosetting component 11B and solder particles 11A is placed on the surface of the first connection target member 2 (first step). . The conductive material 11 used includes a thermosetting compound and a thermosetting agent as the thermosetting component 11B.

A conductive material 11 is placed on the surface of the first connection target member 2 on which the first electrode 2a is provided. After the conductive material 11 is placed, the solder particles 11A are placed both on the first electrode 2a (line) and on the area (space) where the first electrode 2a is not formed.

Methods for disposing the conductive material 11 include, but are not particularly limited to, application using a dispenser, screen printing, and ejection using an inkjet device.

Further, a second connection target member 3 having a second electrode 3a on its surface (lower surface) is prepared. Next, as shown in FIG. 2(b), in the conductive material 11 on the surface of the first connection target member 2, on the surface of the conductive material 11 opposite to the first connection target member 2 side, Arranging the second connection target member 3 (second step). The second connection target member 3 is placed on the surface of the conductive material 11 from the second electrode 3a side. At this time, the first electrode 2a and the second electrode 3a are made to face each other.

Next, the conductive material 11 is heated to a temperature higher than the melting point of the solder particles 11A (third step). Preferably, the conductive material 11 is heated to a temperature higher than the curing temperature of the thermosetting component 11B (thermosetting compound). During this heating, the solder particles 11A existing in the region where no electrode is formed gather between the first electrode 2a and the second electrode 3a (self-agglomeration effect). When a conductive paste is used instead of a conductive film, the solder particles 11A gather more effectively between the first electrode 2a and the second electrode 3a. Further, the solder particles 11A are melted and bonded to each other. Further, the thermosetting component 11B is thermoset. As a result, as shown in FIG. 2(c), the connection portion 4 connecting the first connection target member 2 and the second connection target member 3 is formed of the conductive material 11. A connecting portion 4 is formed by the conductive material 11, a solder portion 4A is formed by joining a plurality of solder particles 11A, and a cured material portion 4B is formed by thermosetting the thermosetting component 11B. If the solder particles 11A move sufficiently, the solder particles 11A that are not located between the first electrode 2a and the second electrode 3a start moving, and then the first electrode 2a and the second electrode 11A start moving. It is not necessary to keep the temperature constant until the movement of the solder particles 11A between the solder particles 3a and the solder particles 11A is completed.

In this embodiment, the following first electrode surface material and conductive material are used as combinations of the first electrode surface material and the conductive material. When the conductive material is coated on a substrate whose surface material is the same as that of the first electrode and heated to 70°C, the amount of metal contained in the conductive particles calculated by EPMA analysis is A material and a conductive material for the surface of the first electrode whose maximum diffusion coefficient is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less . In this embodiment, since the above configuration is provided, solder can be efficiently placed on the electrodes.

In this embodiment, it is preferable not to apply pressure in the second step and the third step. In this case, the weight of the second connection target member 3 is applied to the conductive material 11 . Therefore, when forming the connection portion 4, the solder particles 11A gather more effectively between the first electrode 2a and the second electrode 3a. Note that if pressure is applied in at least one of the second step and the third step, the solder particles 11A tend to gather between the first electrode 2a and the second electrode 3a. are more likely to be inhibited.

Furthermore, in this embodiment, since no pressure is applied, the first connection target member 2 and the second connection target member 3 Even when these electrodes are overlapped, it is possible to correct the deviation and connect the first electrode 2a and the second electrode 3a (self-alignment effect). This is because the molten solder that has self-agglomerated between the first electrode 2a and the second electrode 3a is mixed with the solder between the first electrode 2a and the second electrode 3a and other parts of the conductive material. This is because the energy is more stable when the area of contact with the component is minimized, and a force acts to create an aligned connection structure, which is a connection structure with the minimum area. At this time, it is desirable that the conductive material is not cured and that the viscosity of the components other than the solder particles of the conductive material is sufficiently low at that temperature and time.

The viscosity (ηmp) of the conductive material at the melting point of the solder is preferably 50 Pa·s or less, more preferably 10 Pa·s or less, even more preferably 1 Pa·s or less, preferably 0.1 Pa·s or more, more preferably is 0.2 Pa·s or more. If the viscosity (ηmp) is below the upper limit, the solder can be efficiently aggregated on the electrode. When the viscosity (ηmp) is equal to or higher than the lower limit, it is possible to suppress voids at the connection portion and prevent the conductive material from protruding outside the connection portion.

The above viscosity (ηmp) was measured using STRESSTECH (manufactured by REOLOGICA), etc., with strain control of 1 rad, frequency of 1 Hz, temperature increase rate of 20 °C/min, and measurement temperature range of 25 °C to 200 °C (provided that the melting point of the solder is 200 °C). (If the temperature exceeds the temperature, the upper temperature limit is the melting point of the solder). From the measurement results, the viscosity at the melting point (°C) of the solder is evaluated.

In this way, the connected structure 1 shown in FIG. 1 is obtained. In addition, the said 2nd process and the said 3rd process may be performed continuously. Further, after performing the second step, the obtained laminate of the first connection target member 2, the conductive material 11, and the second connection target member 3 is moved to a heating section, and the third You may perform the process. In order to perform the heating, the laminate may be placed on a heating member, or the laminate may be placed in a heated space.

The heating temperature in the third step is preferably 140°C or higher, more preferably 160°C or higher, preferably 450°C or lower, more preferably 250°C or lower, even more preferably 200°C or lower.

The heating method in the third step includes a method of heating the entire connected structure using a reflow oven or an oven above the melting point of the solder and the curing temperature of the thermosetting component; An example of this method is to locally heat only the connecting portion.

Examples of devices used in the local heating method include a hot plate, a heat gun that applies hot air, a soldering iron, and an infrared heater.

In addition, when heating locally with a hot plate, use a highly thermally conductive metal directly below the connection, and use a low thermally conductive material such as fluororesin for other areas where it is not desirable to heat. , preferably forming the top surface of the hot plate.

The first and second connection target members are not particularly limited. Specifically, the first and second connection target members include semiconductor chips, semiconductor packages, LED chips, LED packages, electronic components such as capacitors and diodes, resin films, printed circuit boards, flexible printed circuit boards, and flexible Examples include electronic components such as flat cables, rigid-flexible boards, circuit boards such as glass epoxy boards, and glass boards. It is preferable that the first and second connection target members are electronic components.

It is preferable that at least one of the first connection target member and the second connection target member is a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible circuit board. It is preferable that the second connection target member is a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible circuit board. Resin films, flexible printed circuit boards, flexible flat cables, and rigid-flexible circuit boards have the properties of being highly flexible and relatively lightweight. When a conductive film is used to connect such connection target members, solder tends to be difficult to collect on the electrodes. On the other hand, by using a conductive paste, even when using a resin film, flexible printed circuit board, flexible flat cable, or rigid-flexible circuit board, the solder can be efficiently collected on the electrodes, thereby improving the continuity reliability between the electrodes. can be sufficiently increased. When using resin films, flexible printed circuit boards, flexible flat cables, or rigid-flex circuit boards, the reliability of conduction between electrodes can be improved by not applying pressure, compared to when using other connection objects such as semiconductor chips. The improvement effect can be obtained even more effectively.

Examples of the electrodes provided on the connection target member include metal electrodes such as gold electrodes, nickel electrodes, tin electrodes, aluminum electrodes, copper electrodes, molybdenum electrodes, silver electrodes, SUS electrodes, and tungsten electrodes. When the member to be connected is a flexible printed circuit board, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, a silver electrode, or a copper electrode. When the member to be connected is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, or a tungsten electrode. In addition, when the said electrode is an aluminum electrode, it may be an electrode formed only with aluminum, and the electrode may be an electrode in which an aluminum layer is laminated|stacked on the surface of a metal oxide layer. Examples of the material for the metal oxide layer include indium oxide doped with a trivalent metal element and zinc oxide doped with a trivalent metal element. Examples of the trivalent metal elements include Sn, Al, and Ga. From the viewpoint of arranging the solder on the electrodes more efficiently, the electrodes provided on the connection target member are preferably gold electrodes, silver electrodes, copper electrodes, or aluminum electrodes.

In the connected structure according to the present invention, it is preferable that the first electrode and the second electrode are arranged in an area array or a peripheral. The effects of the present invention are even more effectively exhibited when the first electrode and the second electrode are arranged in an area array or peripherally. The above-mentioned area array is a structure in which electrodes are arranged in a grid pattern on the surface of the connection target member on which the electrodes are arranged. The above-mentioned peripheral refers to a structure in which electrodes are arranged on the outer periphery of a member to be connected. In the case of a structure in which the electrodes are arranged in a comb shape, the solder only needs to agglomerate along the direction perpendicular to the comb, whereas in the above area array or peripheral structure, the solder aggregates over the entire surface on the surface where the electrodes are arranged. It is necessary for the solder to coagulate uniformly. Therefore, in the conventional method, the amount of solder tends to be uneven, whereas in the method of the present invention, the solder can be uniformly aggregated over the entire surface.

Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples. The invention is not limited only to the following examples.

Thermosetting component (thermosetting compound):
Thermosetting compound 1: Bisphenol F type epoxy compound, "YDF-8170C" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.
Thermosetting compound 2: Bisphenol A type epoxy compound, "YD-8125" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.
Thermosetting compound 3: Phenol novolac type epoxy compound, “DEN431” manufactured by DOW
Thermosetting compound 4: Aliphatic epoxy compound, "Epolite 1600" manufactured by Kyoeisha Chemical Co., Ltd.
Thermosetting compound 5: Isocyanuric skeleton-containing epoxy compound, “TEPIC-SP” manufactured by Nissan Chemical Co., Ltd.

Thermosetting component (thermosetting agent):
Thermosetting agent 1: Acid anhydride curing agent, "Rikacid TH" manufactured by Shin Nippon Rika Co., Ltd.
Thermosetting agent 2: Acid anhydride curing agent, "Rikacid MH" manufactured by Shin Nippon Rika Co., Ltd.

Thermosetting component (hardening accelerator):
Curing accelerator 1: Organic phosphonium salt, “PX-4MP” manufactured by Nihon Kagaku Kogyo Co., Ltd.

flux:
Flux 1: Acidic phosphate ester compound (butyl acid phosphate), “JP-504” manufactured by Johoku Chemical Industry Co., Ltd., liquid at 23°C Flux 2: Acidic phosphoric acid ester compound (ethyl acid phosphate), “JP” manufactured by Johoku Chemical Industry Co., Ltd. -502'', liquid at 23℃ Flux 3: ``Stearic acid'' manufactured by Showa Kagaku Kogyo Co., Ltd., solid at 23℃ Flux 4: ``Diethylphosphonoacetic acid'' manufactured by Johoku Kagaku Kogyo Co., Ltd., liquid at 23℃ Flux 5: ``Glutaric acid'' benzylamine salt, melting point 108°C, solid at 23°C

How to make Flux 5:
24 g of water as a reaction solvent and 13.212 g of glutaric acid (manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a glass bottle and dissolved until uniform at room temperature. Then, 10.715 g of benzylamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred for about 5 minutes to obtain a mixed solution. The resulting mixture was placed in a refrigerator at 5°C to 10°C and left overnight. The precipitated crystals were collected by filtration, washed with water, and vacuum dried to obtain Flux 5.

Flux 6: "Adipic acid benzylamine salt", melting point 171℃, solid at 23℃

How to make Flux 6:
24 g of water as a reaction solvent and 13.89 g of adipic acid (manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a glass bottle and dissolved until uniform at room temperature. Then, 10.715 g of benzylamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred for about 5 minutes to obtain a mixed solution. The resulting mixture was placed in a refrigerator at 5°C to 10°C and left overnight. The precipitated crystals were collected by filtration, washed with water, and vacuum dried to obtain flux 6.

Flux 7: “Azelaic acid” manufactured by Showa Kagaku Kogyo Co., Ltd., solid at 23°C Flux 8: “Sebacic acid” manufactured by Showa Kagaku Kogyo Co., Ltd., solid at 23°C

Conductive particles (solder particles, conductive particles containing solder other than solder particles (conductive particles X)):
Solder particle 1: SnBi solder particles, melting point 138°C, solder particles selected from "Sn42Bi58" manufactured by Mitsui Kinzoku Co., Ltd., average particle size: 20 μm
Solder particle 2: SnBi solder particles, melting point 138°C, solder particles selected from "Sn42Bi58" manufactured by Mitsui Kinzoku Co., Ltd., average particle size: 10 μm
Solder particle 3: SnBi solder particles, melting point 138°C, solder particles selected from "Sn42Bi58" manufactured by Mitsui Kinzoku, average particle size: 7 μm
Solder particle 4: SnBi solder particles, melting point 138°C, solder particles selected from "Sn42Bi58" manufactured by Mitsui Kinzoku, average particle size: 5 μm
Solder particle 5: SnBi solder particles, melting point 138°C, solder particles selected from "Sn66Bi34" manufactured by Mitsui Kinzoku, average particle size: 10 μm
Solder particle 6: SnAgCu solder particle, "SnAg3Cu0.5" manufactured by Mitsui Mining and Mining Co., Ltd., average particle size: 10 μm, melting point: 217 ° C.
Solder particle 7: Silver-plated SnBi solder particles, melting point 138°C, conductive particles made by silver-plating solder particles selected from "Sn42Bi58" manufactured by Mitsui Kinzoku Co., Ltd., average particle size: 10 μm

Method for producing solder particles 7:
20 g of SnBi solder particles having a particle size of 10 μm were placed in 500 g of a 1% by weight citric acid solution to remove the oxide film on the surface of the solder particles. A solution containing 5 g of silver nitrate, 1000 g of ion-exchanged water, 5 g of 1,3-dibromo-5,5-dimethylhydantoin, and 3 g of thiomalic acid was prepared. 50 g of solder particles from which the oxide film was removed were added to the solution and mixed to obtain a suspension. Using the obtained suspension, electrolytic plating was performed under the conditions of an anode: platinum, a cathode: phosphorus-containing copper, and a current density: 2 A/dm ² to form solder particles 7 made of silver-plated SnBi solder particles. Obtained.

Solder particle 8: Nickel-plated SnBi solder particles, melting point 138°C, conductive particles made by nickel-plating solder particles selected from "Sn42Bi58" manufactured by Mitsui Kinzoku Co., Ltd., average particle size: 10 μm

Method for producing solder particles 8:
20 g of SnBi solder particles having a particle diameter of 10 μm were electrolytically plated using a flow-through plater under the conditions of a dome diameter of 280 mm, revolution of 234 rpm, 22.8 A/dm ² , and 2 hours. Watt Ni (Supplea Nickel AEP-1) was used as the plating bath, and steel balls were used as the conductive media at a packing density of 4.74. Solder particles 8, which were SnBi solder particles plated with nickel, were obtained by the electrolytic plating described above.

(Examples 1-8, 12-19 , Reference Examples 9-11 and Comparative Examples 1-5)
(1) Preparation of conductive material (anisotropic conductive paste) A conductive material (anisotropic conductive paste) was obtained by blending the ingredients shown in Tables 1 and 2 below in the amounts shown in Tables 1 and 2 below. Ta.

(2) Preparation of the first connection structure As the first connection target member, a glass epoxy substrate (material: : FR-4, thickness: 0.6 mm) was prepared.

As the second connection target member, a flexible printed circuit board (material: polyimide, thickness: 0.1 mm) with a gold electrode (electrode length: 3 mm, electrode thickness: 12 μm) with L/S = 50 μm/50 μm on the surface is prepared. did.

A conductive material (anisotropic conductive paste) immediately after preparation was applied to a thickness of 100 μm on the upper surface of the glass epoxy substrate to form a conductive material (anisotropic conductive paste) layer. Next, a flexible printed circuit board was laminated on the upper surface of the conductive material (anisotropic conductive paste) layer so that the electrodes faced each other. The weight of the flexible printed circuit board is added to the conductive material (anisotropic conductive paste) layer. From this state, the temperature of the conductive material (anisotropic conductive paste) layer was heated to the melting point of the conductive particles 5 seconds after the start of temperature rise. Furthermore, 15 seconds after the start of temperature rise, the conductive material (anisotropic conductive paste) layer is heated to a temperature of 160°C to harden the conductive material (anisotropic conductive paste) layer, and the connected structure is formed. Obtained. No pressure was applied during heating.

(3) Preparation of second connection structure As the first connection target member, a glass epoxy substrate (material: : FR-4, thickness: 0.6 mm) was prepared.

As the second connection target member, a flexible printed circuit board (material: polyimide, thickness: 0.1 mm) having a silver electrode (electrode length: 3 mm, electrode thickness: 12 μm) with L/S = 50 μm/50 μm on the surface is prepared. did.

A conductive material (anisotropic conductive paste) immediately after preparation was applied to a thickness of 100 μm on the upper surface of the glass epoxy substrate to form a conductive material (anisotropic conductive paste) layer. Next, a flexible printed circuit board was laminated on the upper surface of the conductive material (anisotropic conductive paste) layer so that the electrodes faced each other. The weight of the flexible printed circuit board is added to the conductive material (anisotropic conductive paste) layer. From this state, the conductive material (anisotropic conductive paste) layer was heated so that the temperature reached the melting point of the conductive particles 5 seconds after the start of temperature rise. Furthermore, 15 seconds after the start of temperature rise, the conductive material (anisotropic conductive paste) layer is heated to a temperature of 160°C to harden the conductive material (anisotropic conductive paste) layer, and the connected structure is formed. Obtained. No pressure was applied during heating.

(4) Preparation of third connection structure As the first connection target member, a glass epoxy substrate (material: : FR-4, thickness: 0.6 mm) was prepared.

As the second connection target member, a flexible printed circuit board (material: polyimide, thickness: 0.1 mm) with copper electrodes (electrode length: 3 mm, electrode thickness: 12 μm) with L/S = 50 μm/50 μm on the surface is prepared. did.

A conductive material (anisotropic conductive paste) immediately after preparation was applied to a thickness of 100 μm on the upper surface of the glass epoxy substrate to form a conductive material (anisotropic conductive paste) layer. Next, a flexible printed circuit board was laminated on the upper surface of the conductive material (anisotropic conductive paste) layer so that the electrodes faced each other. The weight of the flexible printed circuit board is added to the conductive material (anisotropic conductive paste) layer. From this state, the temperature of the conductive material (anisotropic conductive paste) layer was heated to the melting point of the conductive particles 5 seconds after the start of temperature rise. Furthermore, 15 seconds after the start of temperature rise, the conductive material (anisotropic conductive paste) layer is heated to a temperature of 160°C to harden the conductive material (anisotropic conductive paste) layer, and the connected structure is formed. Obtained. No pressure was applied during heating.

(5) Preparation of the fourth connection structure As the first connection target member, a glass epoxy substrate (material: : FR-4, thickness: 0.6 mm) was prepared.

As the second connection target member, a flexible printed circuit board (material: polyimide, thickness: 0.1 mm) having an aluminum electrode (electrode length: 3 mm, electrode thickness: 12 μm) with L/S = 50 μm/50 μm on the surface is prepared. did.

A conductive material (anisotropic conductive paste) immediately after preparation was applied to a thickness of 100 μm on the upper surface of the glass epoxy substrate to form a conductive material (anisotropic conductive paste) layer. Next, a flexible printed circuit board was laminated on the upper surface of the conductive material (anisotropic conductive paste) layer so that the electrodes faced each other. The weight of the flexible printed circuit board is added to the conductive material (anisotropic conductive paste) layer. From this state, the temperature of the conductive material (anisotropic conductive paste) layer was heated to the melting point of the conductive particles 5 seconds after the start of temperature rise. Furthermore, 15 seconds after the start of temperature rise, the conductive material (anisotropic conductive paste) layer is heated to a temperature of 160°C to harden the conductive material (anisotropic conductive paste) layer, and the connected structure is formed. Obtained. No pressure was applied during heating.

(evaluation)
(1) Diffusion coefficient showing maximum value A substrate was prepared whose surface material was the same as that of the surface material (gold, silver, copper, or aluminum) of the electrodes of the first, second, third, and fourth connection target members.

The obtained conductive material was applied to a substrate whose surface material was gold, heated to 70° C., and the diffusion coefficient of the metal contained in the conductive particles was calculated by EPMA analysis. Among the obtained metal diffusion coefficients, the diffusion coefficient showing the maximum value was designated as DAu. DAu was evaluated based on the following criteria.

The obtained conductive material was applied to a substrate whose surface material was silver, heated to 70° C., and the diffusion coefficient of metal contained in the conductive particles was calculated by EPMA analysis. Among the obtained metal diffusion coefficients, the diffusion coefficient showing the maximum value was defined as DAg. DAg was determined based on the following criteria.

The obtained conductive material was applied to a substrate whose surface material was copper, heated to 70° C., and the diffusion coefficient of metal contained in the conductive particles was calculated by EPMA analysis. Among the obtained metal diffusion coefficients, the diffusion coefficient showing the maximum value was designated as DCu. DCu was evaluated based on the following criteria.

The obtained conductive material was applied to a substrate whose surface material was aluminum, heated to 70° C., and the diffusion coefficient of metal contained in the conductive particles was calculated by EPMA analysis. Among the obtained metal diffusion coefficients, the diffusion coefficient showing the maximum value was designated as DAl. DAl was determined based on the following criteria.

[Judgment criteria for diffusion coefficient showing maximum value (DAu, DAg, DCu or DAl)]
○○: Diffusion coefficient (DAu, DAg, DCu or DAl) showing the maximum value is 1.0 x 10 ^-20 m ² /s or more and less than 1.0 x 10 ^-14 m ² /s ○: Diffusion showing the maximum value The coefficient (DAu, DAg, DCu or DAl) is 1.0×10 ^-23 m ² /s or more and less than 1.0×10 ^-20 m ² /s △: Diffusion coefficient showing the maximum value (DAu, DAg, DCu or DAl) is 1.0×10 ^-26 m ² /s or more and less than 1.0×10 ^-23 m ² /s ×: Diffusion coefficient showing the maximum value (DAu, DAg, DCu or DAl) is 1.0×10 Less than ^-26 m ² /s

(2) Accuracy of placement of solder on electrodes In the obtained first, second, third, and fourth connected structures, the first electrode and the second electrode are arranged in the stacking direction of the first electrode, the connection part, and the second electrode. When looking at the part where the first electrode and the second electrode face each other, the ratio of the area where the solder part in the connection part is located to the 100% area of the part where the first electrode and the second electrode face each other. Evaluated X. The placement accuracy of the solder on the electrode was judged based on the following criteria.

[Criteria for determining accuracy of solder placement on electrodes]
○○○: Proportion X is 80% or more ○○: Proportion X is 70% or more and less than 80% ○: Proportion X is 60% or more and less than 70% △: Proportion %less than

(3) Migration A migration test (left for 100 hours under the conditions of temperature 110°C, humidity 85%, and 5V application) was conducted on the obtained first, second, third, and fourth connected structures. After the migration test, the connection resistance between the upper and lower electrodes was measured using a four-terminal method. Note that from the relationship of voltage=current×resistance, insulation resistance can be determined by measuring the voltage when a constant current is passed. Migration was judged based on the following criteria.

[Migration criteria]
〇〇: Average value of insulation resistance after migration test is 1.0 x 10 ¹⁴ Ω or more
○: The average value of insulation resistance after the migration test is 1.0×10 ¹² Ω or more and less than 1.0×10 ¹⁴ Ω △: The average value of the insulation resistance after the migration test is 1.0×10 ¹⁰ Ω or more 1. Less than 0×10 ¹² Ω ×: The average value of insulation resistance after the migration test is less than 1.0×10 ¹⁰ Ω, indicating insulation failure.

The results are shown in Tables 1 and 2 below.

A similar tendency was observed even when resin films, flexible flat cables, and rigid-flexible substrates were used.

1, 1X... Connection structure 2... First connection target member 2a... First electrode 3... Second connection target member 3a... Second electrode 4, 4X... Connection part 4A, 4XA... Solder part 4B, 4XB ...Cured product part 11...Conductive material 11A...Solder particle 11B...Thermosetting component 21...Electroconductive particle 31...Electroconductive particle 32...Base material particle 33...Conductive part 33A...Second conductive part 33B...First conductive part Part 41...Conductive particle 42...Conductive part

Claims (10)

A conductive material containing a thermosetting component, a flux, and conductive particles containing solder,
the flux is liquid at 23°C;
When the conductive material is applied to a substrate whose surface material is gold and heated to 70 ° C., the diffusion coefficient that indicates the maximum value among the diffusion coefficients of the metal contained in the conductive particles calculated by EPMA analysis. is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less. A conductive material containing a thermosetting component, a flux, and conductive particles containing solder,
the flux is liquid at 23°C;
When the conductive material is applied to a substrate whose surface material is silver and heated to 70 ° C., the diffusion coefficient that indicates the maximum value among the diffusion coefficients of metals contained in the conductive particles calculated by EPMA analysis. is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less. A conductive material containing a thermosetting component, a flux, and conductive particles containing solder,
the flux is liquid at 23°C;
When the conductive material is applied to a substrate whose surface material is copper and heated to 70°C, the diffusion coefficient that indicates the maximum value among the diffusion coefficients of metals contained in the conductive particles calculated by EPMA analysis. is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less. A conductive material containing a thermosetting component, a flux, and conductive particles containing solder,
the flux is liquid at 23°C;
When the conductive material is applied to a substrate whose surface material is aluminum and heated to 70°C, the diffusion coefficient that indicates the maximum value among the diffusion coefficients of metals contained in the conductive particles calculated by EPMA analysis. is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m ² /s or less. The conductive material according to any one of claims 1 to 4 , wherein the conductive particles containing the solder have a particle size of 35 μm or less. The conductive material according to any one of claims 1 to 5 , which is a conductive paste. a first connection target member having a first electrode on its surface;
a second connection target member having a second electrode on its surface;
comprising a connection part connecting the first connection target member and the second connection target member,
The material of the connecting portion is the conductive material according to any one of claims 1 to 6 ,
A connection structure in which the first electrode and the second electrode are electrically connected by a solder part in the connection part. A conductive material containing a thermosetting component, a flux, and conductive particles containing solder is used, and the conductive material is disposed on the surface of a first connection target member having a first electrode on the surface. Step 1 and
A second connection target member having a second electrode on its surface is placed on a surface of the conductive material opposite to the first connection target member side, and the first electrode and the second electrode are opposite to each other. a second step of arranging the
A connecting portion connecting the first connection target member and the second connection target member is formed from the conductive material by heating the conductive material to a temperature higher than the melting point of the conductive particles, and , a third step of electrically connecting the first electrode and the second electrode by a solder part in the connecting part,
the flux is liquid at 23°C;
As a combination of the surface material of the first electrode and the conductive material, when the conductive material is coated on a substrate whose surface material is the same as the material of the surface of the first electrode and heated to 70 ° C. Among the diffusion coefficients of the metal contained in the conductive particles calculated by EPMA analysis, the maximum diffusion coefficient is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m A method for manufacturing a connected structure using a material for the surface of a first electrode and a conductive material that has a conductivity of ² /s or less. As a combination of the surface material of the second electrode and the conductive material, when the conductive material is coated on a substrate whose surface material is the same as the material of the surface of the second electrode and heated to 70 ° C. Among the diffusion coefficients of the metal contained in the conductive particles calculated by EPMA analysis, the maximum diffusion coefficient is 1.0×10 ⁻²³ m ² /s or more and 1.0×10 ⁻¹⁴ m 9. The method for manufacturing a connected structure according to claim 8 , wherein a material for the surface of the second electrode and a conductive material are used which have a conductivity of ² /s or less. The method for manufacturing a connected structure according to claim 8 or 9 , wherein the first electrode and the second electrode are gold electrodes, silver electrodes, copper electrodes, or aluminum electrodes.

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