JP2023138947A - Conductive material, connection structure and method for producing connection structure - Google Patents

Abstract

To provide a conductive material that allows solder to be efficiently disposed on an electrode, and can effectively improve conduction reliability between vertical electrodes to be connected.SOLUTION: A conductive material has a thermosetting component and a solder particle. An absolute difference between a solidus temperature of the solder particle and a liquidus temperature of the solder particle is 5°C or more. In the conductive material 100 wt.%, the content of the solder particles is 15 wt.% or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to a conductive material containing a thermosetting component and solder 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 an anisotropic conductive material containing a large number of conductive particles in a thermosetting resin. The conductive particles have a solidus temperature of 125°C or higher and a peak temperature of 200°C or lower. The temperature difference between the solidus temperature of the conductive particles and the peak temperature of the conductive particles is 15° C. or more.

Patent Document 2 below discloses a thermosetting resin composition containing solder particles, a thermosetting resin binder, and a flux component. The solder particles are made of an alloy of Sn and a metal selected from Ag, Cu, Bi, Zn, or In. The melting point of the solder particles is 240°C or lower. The thermosetting resin binder includes a liquid epoxy resin and a liquid phenolic resin curing agent. In the thermosetting resin composition, the content of the solder particles is in the range of 70% by mass to 95% by mass. The solder particles are dispersed in the thermosetting resin composition. The thermosetting resin composition can be applied to the surface of a wiring board.

WO2008/111615A1 Japanese Patent Application Publication No. 2014-98168

When making a conductive connection using a conductive material containing solder particles, a plurality of upper electrodes and a plurality of lower electrodes are electrically connected to make a conductive connection. The solder is desirably placed between the upper and lower electrodes, and desirably not placed between adjacent lateral electrodes. It is desirable that adjacent horizontal electrodes are not electrically connected.

In general, a conductive material containing solder particles is placed on a substrate and then heated by reflow or the like before use. When the conductive material is heated above the melting point of the solder particles, the solder particles melt and the solder aggregates between the electrodes, thereby electrically connecting the upper and lower electrodes.

In conventional conductive materials containing solder particles, when the conductive material is heated, the solder particles may melt and the fluidity of the solder may become too high. If the fluidity of the solder becomes too high, the agglomeration rate of the solder may become too fast. In conventional conductive materials containing solder particles, the solder agglomeration rate is too fast, so that the solder remains between adjacent lateral electrodes, and all the solder cannot aggregate on the electrodes and should be connected. Solder may not be efficiently placed between the upper and lower electrodes. As a result, the amount of solder placed between the upper and lower electrodes to be connected is reduced, reducing the continuity reliability between the upper and lower electrodes to be connected, and the insulation reliability between adjacent lateral electrodes. may become low. With conventional conductive materials, it is difficult to adjust the cohesive force of solder.

Further, in the anisotropic conductive material described in Patent Document 1, the content of the conductive particles is small, making it difficult to electrically connect the electrodes.

An object of the present invention is to provide a conductive material that allows solder to be efficiently disposed on electrodes and effectively increases the reliability of conduction between upper and lower electrodes to be connected. 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 present invention includes a thermosetting component and solder particles, and the absolute value of the difference between the solidus temperature of the solder particles and the liquidus temperature of the solder particles is 5° C. or more. There is provided a conductive material in which the content of the solder particles is 15% by weight or more based on 100% by weight of the conductive material.

In a particular aspect of the conductive material according to the present invention, the viscosity of the conductive material at the solidus temperature of the solder particles is 0.1 Pa·s or more and 50 Pa·s or less.

In a particular aspect of the conductive material according to the present invention, the solder particles contain bismuth, indium, silver, copper, or tin.

In a particular aspect of the conductive material according to the present invention, the content of bismuth is 1% by weight or more and 58% by weight or less in 100% by weight of metal contained in the solder particles.

In a particular aspect of the conductive material according to the present invention, the content of indium is 1% by weight or more and 52% by weight or less in 100% by weight of metal contained in the solder particles.

In a particular aspect of the conductive material according to the present invention, the solidus temperature of the solder particles is 115°C or more and 220°C or less.

In a particular aspect of the conductive material according to the present invention, the solder particles have a particle size of 0.01 μm or more and 30 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.

In a particular aspect of the connection structure according to the present invention, the first electrode and the second electrode may face each other in a stacking direction of the first electrode, the connection portion, and the second electrode. When looking at the portion, the solder portion in the connection portion is disposed on 50% or more of the 100% area of the portion where the first electrode and the second electrode face each other.

According to a broad aspect of the present invention, the above-described conductive material is disposed on the surface of a first connection target member having a first electrode on its surface; A second connection target member having a second electrode on its surface is arranged on a surface opposite to the first connection target member side so that the first electrode and the second electrode face each other. By heating the conductive material above the liquidus temperature of the solder particles, the connecting portion connecting the first connection target member and the second connection target member is heated to the conductive material. and electrically connecting the first electrode and the second electrode with a solder part in the connecting part.

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 stacked in the stacking direction of the first electrode, the connecting portion, and the second electrode. A connection in which the solder part in the connecting part is arranged in 50% or more of the 100% area of the facing part of the first electrode and the second electrode when looking at the facing parts. Get the struct.

The electrically conductive material according to the present invention includes a thermosetting component and solder particles. In the conductive material according to the present invention, the absolute value of the difference between the solidus temperature of the solder particles and the liquidus temperature of the solder particles is 5° C. or more. In the conductive material according to the present invention, the content of the solder particles is 15% by weight or more based on 100% by weight of the conductive material. Since the conductive material according to the present invention has the above configuration, the solder can be efficiently placed on the electrodes, and the reliability of conduction between the upper and lower electrodes to be connected can be effectively increased. I can do it.

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.

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 and solder particles. In the conductive material according to the present invention, the absolute value of the difference between the solidus temperature of the solder particles and the liquidus temperature of the solder particles is 5° C. or more. In the conductive material according to the present invention, the content of the solder particles is 15% by weight or more based on 100% by weight of the conductive material.

Since the conductive material according to the present invention has the above configuration, the solder can be efficiently placed on the electrodes, and the reliability of conduction between the upper and lower electrodes to be connected can be effectively increased. I can do it.

In the conductive material according to the present invention, since the content of the solder particles is 15% by weight or more in 100% by weight of the conductive material, the solder can be aggregated on the electrodes, and between the upper and lower electrodes to be connected. Solder can be placed efficiently. In the present invention, it is an important configuration for obtaining the effects of the present invention that the content of the solder particles satisfies the above range.

A conductive material containing solder particles is placed on a substrate and then heated by reflow or the like before use. When the conductive material is heated above the melting point of the solder particles, the solder particles melt and the solder aggregates between the electrodes, thereby electrically connecting the upper and lower electrodes.

In conventional conductive materials containing solder particles, when the conductive material is heated, the solder particles may melt and the fluidity of the solder may become too high. If the fluidity of the solder becomes too high, the agglomeration rate of the solder may become too fast. In conventional conductive materials containing solder particles, the solder agglomeration rate is too fast, so that the solder remains between adjacent lateral electrodes, and all the solder cannot aggregate on the electrodes and should be connected. Solder may not be efficiently placed between the upper and lower electrodes.

The present inventors focused on the absolute value of the difference between the solidus temperature of the solder particles and the liquidus temperature of the solder particles, and by using specific solder particles, the fluidity of the solder was adjusted. It has been found that the aggregation rate can be adjusted. In the present invention, by appropriately adjusting the fluidity of the solder and the cohesive force of the solder, the solder can be efficiently placed between the electrodes to be connected, and the continuity between the upper and lower electrodes to be connected can be ensured. It can effectively improve your sexuality.

Further, by appropriately adjusting the fluidity of the solder and the cohesive force of the solder, it is possible to reduce the amount of solder remaining between adjacent horizontal electrodes. As a result, the insulation reliability between adjacent horizontal electrodes that should not be connected can be effectively increased.

Furthermore, since the present invention has the above-mentioned configuration, when the electrodes are electrically connected, the solder tends to gather between the upper and lower opposing electrodes, and the solder can be placed on the electrodes (lines). I can do it. Further, it is difficult for a portion of the solder to be placed between the lateral electrodes that should not be connected, and the amount of solder that is placed between the lateral electrodes that should not be connected can be considerably reduced. 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 inclusion of specific solder particles in the conductive material 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. Preferably, the conductive material is a conductive paste at 25°C.

From the viewpoint of disposing the solder on the electrode more efficiently, the viscosity (η25) at 25°C of the conductive material is preferably 0.1 Pa·s or more, more preferably 30 Pa·s or more, and even more preferably It is 50 Pa·s or more, preferably 400 Pa·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.

The viscosity (ηsp) of the conductive material at the solidus temperature of the solder particles is preferably 0.1 Pa·s or more, more preferably 0.2 Pa·s or more, and preferably 50 Pa·s or less, more preferably 10 Pa·s.・S or less. When the viscosity (ηsp) is not less than the lower limit and not more than the upper limit, the solder can be more efficiently placed on the electrodes, and the continuity reliability between the upper and lower electrodes to be connected can be further improved. can be improved.

The viscosity (ηsp) of the conductive material at the solidus temperature of the solder particles was determined using STRESSTECH (manufactured by REOLOGICA), strain control 1 rad, frequency 1 Hz, temperature increase rate 20 °C/min, measurement temperature range 25 °C ~ Measurement is possible under the condition of 200°C (however, if the solidus temperature of the solder particles exceeds 200°C, the upper temperature limit is set to the solidus temperature of the solder particles). From the measurement results, the viscosity of the solder particles at the solidus temperature (° C.) is evaluated.

The viscosity (ηmp) of the conductive material at the liquidus temperature (melting point) of the solder particles is preferably 50 Pa·s or less, more preferably 10 Pa·s or less, still more preferably 1 Pa·s or less, and preferably 0. It is 1 Pa·s or more, more preferably 0.2 Pa·s or more. If the viscosity (ηmp) is below the upper limit, the solder can be efficiently aggregated on the electrode. If the above-mentioned viscosity is more than the above-mentioned lower limit, it is possible to suppress voids in the connection portion and to suppress 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 (however, the liquidus line of the solder particles When the temperature (melting point) exceeds 200° C., measurement can be performed under the condition that the upper temperature limit is the liquidus temperature (melting point) of the solder particles. From the measurement results, the viscosity at the liquidus temperature (melting point) (°C) of the solder particles is evaluated.

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. In addition, in this specification, "(meth)acrylic" means one or both of "acrylic" and "methacrylic."

(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. When conductive particles comprising base particles made of a material other than solder and a solder portion disposed on the surface of the base particles are used instead of the solder particles described above, conductive particles can be placed on the electrodes. Particles become difficult to collect. In addition, since the conductive particles described above have low solder bondability between conductive particles, the conductive particles that have moved onto the electrode tend to move out of the electrode, and the effect of suppressing misalignment between the electrodes is also low. tends to be lower.

The solder is preferably a metal (low melting point metal) whose liquidus temperature (melting point) is 450° C. or lower. The solder particles are preferably metal particles (low melting point metal particles) having a liquidus temperature (melting point) of 450° C. or lower. The low melting point metal particles are particles containing a low melting point metal. The low melting point metal refers to a metal whose liquidus temperature (melting point) is 450° C. or lower. The liquidus temperature (melting point) of the low melting point metal is preferably 300°C or lower, more preferably 220°C or lower, even more preferably 190°C or lower.

The liquidus temperature of the solder particles is preferably 140°C or higher, more preferably 145°C or higher, and preferably 230°C or lower, more preferably 225°C or lower. When the liquidus temperature 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, and the continuity reliability between the upper and lower electrodes to be connected is improved. It can be improved even more effectively.

The solidus temperature of the solder particles is preferably 115°C or higher, more preferably 120°C or higher, and preferably 220°C or lower, more preferably 150°C or lower, and even more preferably 145°C or lower. When the solidus temperature 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, and the continuity reliability between the upper and lower electrodes to be connected is improved. It can be improved even more effectively.

In the conductive material, the absolute value of the difference between the solidus temperature of the solder particles and the liquidus temperature of the solder particles is 5° C. or more. The absolute value of the difference between the solidus temperature of the solder particles and the liquidus temperature of the solder particles is preferably 5°C or higher, more preferably 8°C or higher, and preferably 100°C or lower, more preferably 90°C or higher. below ℃. When the absolute value of the difference between the solidus temperature of the solder particles and the liquidus temperature of the solder particles is greater than or equal to the lower limit and less than the upper limit, it is possible to more efficiently arrange the solder on the electrode. This makes it possible to further effectively improve the reliability of conduction between the upper and lower electrodes to be connected.

The liquidus temperature of the solder particles and the solidus temperature of the solder particles can be determined by differential scanning calorimetry (DSC). The differential scanning calorimetry (DSC) described above is preferably performed under the following conditions: temperature increase range: 30° C. to 500° C., temperature increase rate: 5° C./min, and nitrogen purge amount: 5 ml/min. Examples of the differential scanning calorimetry (DSC) device include "EXSTAR DSC7020" manufactured by SII. For the obtained differential scanning calorimetry (DSC) curve, draw a straight line extending the baseline on the low temperature side to the high temperature side, and draw a tangent (tangent line 1) at the point where the slope of the curve on the low temperature side of the melting peak is maximum. . The temperature at the intersection of the straight line extended to the high temperature side and the tangent line (tangent line 1) is defined as the solidus temperature. In addition, for the obtained differential scanning calorimetry (DSC) curve, draw a straight line extending the baseline on the high temperature side to the low temperature side, and draw a tangent (tangent line 2) at the point where the slope of the curve on the high temperature side of the melting peak is maximum. pull. The temperature at the intersection of the straight line extended to the low temperature side and the tangent line (tangent line 2) is defined as the liquidus temperature.

The solidus temperature of the solder particles, the liquidus temperature of the solder particles, and the absolute value of the difference between the solidus temperature of the solder particles and the liquidus temperature of the solder particles are adjusted to the above preferred ranges. Examples of the method include a method of adjusting the type and content of metal contained in the solder particles.

The solder particles preferably contain bismuth, indium, silver, copper, or tin, more preferably bismuth, indium, or tin, and even more preferably bismuth or indium. When the above-mentioned solder particles satisfy the above-mentioned preferred embodiments, the solder can be arranged on the electrodes more efficiently, and the reliability of conduction between the upper and lower electrodes to be connected can be further effectively increased. can.

The content of tin in 100% by weight of metal contained in the solder particles is preferably 30% by weight or more, more preferably 40% by weight or more, and preferably 90% by weight or less, more preferably 70% by weight or less. be. When the content of tin in the solder particles is at least the above lower limit and below the above upper limit, the conduction reliability and connection reliability between the solder portion and the electrode become even higher.

The content of bismuth is preferably 1% by weight or more, more preferably 2% by weight or more, and preferably 58% by weight or less, more preferably 55% by weight or less in 100% by weight of the metal contained in the solder particles. be. When the content of bismuth in the solder particles 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 continuity reliability between the upper and lower electrodes to be connected is improved. It can be improved even more effectively.

In 100% by weight of metal contained in the solder particles, the content of indium is preferably 1% by weight or more, more preferably 2% by weight or more, and preferably 52% by weight or less, more preferably 45% by weight or less. be. When the content of indium in the solder particles 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 continuity reliability between the upper and lower electrodes to be connected is improved. It can be improved even more effectively.

The above content of tin, bismuth, or indium is measured using a high-frequency inductively coupled plasma emission spectrometer (ICP-AES manufactured by Horiba) or a fluorescent X-ray analyzer (EDX-800HS manufactured by Shimadzu Corporation). ) etc. can be used for measurement.

By using the above-mentioned solder particles, the solder melts and joins 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. The solder particles preferably do not contain lead, and preferably contain tin and indium, or tin and bismuth. The solder particles may include eutectic solder. When the solder particles include eutectic solder, it is preferable to mix a plurality of solder particles so that the absolute value of the difference between the solidus temperature and the liquidus temperature is 5° C. or more.

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 0.01 μm or more, more preferably 1 μm or more, even more preferably 2 μm or more, particularly preferably 3 μm or more, and preferably 30 μm or less, more preferably 20 μm or less, and even more preferably 10 μm. It is as follows. When the particle diameter of the solder 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. It is particularly preferable that the particle diameter of the solder particles is 3 μm or more and 10 μm or less.

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 average 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 or may have a shape other than spherical, such as a flat shape.

In the conductive material, the content of the solder particles is 15% by weight or more based on 100% by weight of the conductive material. The content of the solder particles in 100% by weight of the conductive material is preferably 20% by weight or more, more preferably 30% by weight or more, even more preferably 40% by weight or more, and preferably 90% by weight or less, more preferably It is 85% by weight or less, 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 becomes even higher. From the viewpoint of further improving conduction reliability, it is preferable that the content of the solder particles is large.

(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 increase the degree of curing of the conductive material, the conductive material preferably contains a thermosetting compound and a thermosetting agent as thermosetting components. In order to increase the degree of curing of the conductive material, 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 if the epoxy compound is solid at room temperature, the melting temperature of the epoxy compound is below the liquidus temperature of the solder particles. is preferred. 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 arranging the solder on the electrode more effectively, 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, preferably 85% by weight or less, more preferably 75% by weight or less, and It is preferably 65% by weight or less, particularly preferably 55% 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, and preferably 85% by weight or less, more preferably 75% by weight or less, and even more preferably It is 65% by weight or less, particularly preferably 55% 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 liquidus temperature of the solder particles, more preferably 5° C. or more higher. , more preferably 10°C or more.

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. With respect to 100 parts by weight of the thermosetting compound, 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 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 surplus 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, organic acid dihydrazide and other amine compounds, 1,8-diazabicyclo[5,4,0]undecene-7,3,9-bis(3-aminopropyl) Examples include -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 may contain 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 or pine resin having two or more carboxyl groups, 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.

The activation temperature (melting point) of the above flux is preferably 50°C or higher, more preferably 70°C or higher, even more preferably 80°C or higher, preferably 200°C or lower, more preferably 190°C or lower, even more preferably 160°C or lower. The temperature is preferably 150°C or lower, even more preferably 140°C or lower. When the activation temperature of the flux is equal to or higher than the lower limit and lower than the upper limit, the flux effect is even more effectively exhibited, and the solder is disposed on the electrode more efficiently. The activation temperature (melting point) of the flux is preferably 80°C or more and 190°C or less. It is particularly preferable that the activation temperature (melting point) of the above-mentioned flux is 80°C or more and 140°C or less.

Examples of the above-mentioned fluxes having an active temperature (melting point) of 80°C or higher and 190°C or lower include succinic acid (melting point 186°C), glutaric acid (melting point 96°C), adipic acid (melting point 152°C), and pimelic acid (melting point 104°C). C), dicarboxylic acids such as suberic acid (melting point 142°C), benzoic acid (melting point 122°C), and malic acid (melting point 130°C).

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

From the viewpoint of disposing the solder on the electrode more efficiently, the melting point of the flux is preferably higher than the liquidus temperature of the solder particles, more preferably 5°C or more, more preferably 10°C or more. It is more preferable that it is high.

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

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

Since the melting point of the flux is higher than the liquidus temperature of the solder particles, the solder can be efficiently aggregated on the electrode portion. This means that when heat is applied during bonding, when comparing the electrode formed on the member to be connected and the part of the member to be connected around the electrode, the thermal conductivity of the electrode part is lower than that of the part of the member to be connected around the electrode. This is due to the fact that the temperature of the electrode portion rises quickly due to its higher thermal conductivity. When the temperature exceeds the liquidus temperature of the solder particles, the inside of the solder particles melts, but the oxide film formed on the surface is not removed because it has not reached the melting point (activation temperature) of the flux. In this state, the temperature of the electrode reaches the melting point (activation temperature) of the flux first, so the oxide film on the surface of the solder particles that have moved onto the electrode is removed preferentially, and the solder wets the surface of the electrode. It can expand. Thereby, the solder can be efficiently aggregated on the electrode.

The above-mentioned flux is preferably a flux that releases cations when heated. By using a flux that releases cations when heated, the solder can be placed on the electrodes more efficiently.

Examples of the flux that releases cations upon heating include the thermal cation initiator (thermal cation curing agent).

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 includes a step of using the above-mentioned conductive material and arranging the above-described conductive material on the surface of a first connection target member having a first electrode on the surface. 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 step of arranging the first electrode and the second electrode so as 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 liquidus temperature of the solder particles. forming a connecting portion made of the conductive material, and electrically connecting the first electrode and the second electrode with a solder portion in the connecting portion.

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 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 and solder particles. The thermosetting component includes a thermosetting compound and a thermosetting agent. 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 connection portion 4, no solder exists 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 is no solder separate from the solder portion 4A. Note that solder 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 solder separate from the solder portion 4XA. In addition, in this embodiment, the amount of solder separated from the solder part can be reduced, but the solder 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, 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 energy is more stable when the area in contact with the component is minimized, and a force acts to create an aligned connection structure that has 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.

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 heating the entire connected structure to a temperature above the liquidus temperature (melting point) of the solder particles and above the curing temperature of the thermosetting component using a reflow oven or an oven. Examples include a method of heating only the connecting portion of the connected structure locally.

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.

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 non-uniform, whereas in the method of the present invention, the effects of the present invention are more effectively exhibited.

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: “Glutaric acid benzylamine salt”, melting point 108°C
How to make Flux 1:
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 1.

Solder particles:
Solder particle 1: Sn42Bi58 solder particle, average particle size 10 μm
Solder particle 2: Sn66Bi34 solder particle, average particle diameter 10 μm
Solder particle 3: Sn53Bi47 solder particle, average particle size 10 μm
Solder particle 4: Sn90In10 solder particle, average particle size 10 μm
Solder particle 5: SnIn8Ag3.5 solder particle, average particle size 10 μm
Solder particle 6: SnAg3Cu0.5 solder particle, average particle size 10 μm

(Examples 1 to 24 and Comparative Examples 1 to 12)
(1) Preparation of conductive material (anisotropic conductive paste) The components shown in Tables 1 to 3 below are mixed in the amounts shown in Tables 1 to 3 below to obtain a conductive material (anisotropic conductive paste). Ta.

(2) Preparation of 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 solidus temperature of the solder 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 200°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) Solidus temperature of solder particles, liquidus temperature of solder particles, and absolute value of the difference between solidus temperature of solder particles and liquidus temperature of solder particles Solidus temperature of solder particles and solder The liquidus temperature of the particles was measured using differential scanning calorimetry (DSC) as follows. As a differential scanning calorimetry (DSC) device, "EXSTAR DSC7020" manufactured by SII was used.

(Method for measuring solidus temperature of solder particles and liquidus temperature of solder particles)
Approximately 10 mg of the above solder particles were weighed out, the sample was placed approximately in the center of an aluminum container (sample container), and the aluminum lid of the container was placed and clamped. The obtained sample container was attached to one container holder of a differential scanning calorimetry (DSC) device. The other container holder was equipped with an empty aluminum container (sample container) in which no sample was placed and the aluminum lid was clamped. Further, the nitrogen gas flow rate was set to an appropriate value in the range of 10 ml/min to 50 ml/min, and the nitrogen gas was allowed to flow until the end of the measurement. The temperature was raised at a rate of 10° C./min, and measurements were taken while heating to a temperature approximately 30° C. higher than the end of the melting peak. For the obtained differential scanning calorimetry (DSC) curve, draw a straight line extending the baseline on the low temperature side to the high temperature side, and draw a tangent (tangent 1) at the point where the slope of the curve on the low temperature side of the melting peak is maximum. Ta. The temperature at the intersection of the straight line extended to the high temperature side and the tangent line (tangent line 1) was defined as the solidus temperature. In addition, for the obtained differential scanning calorimetry (DSC) curve, draw a straight line extending the baseline on the high temperature side to the low temperature side, and draw a tangent (tangent line 2) at the point where the slope of the curve on the high temperature side of the melting peak is maximum. I subtracted. The temperature at the intersection of the straight line extended to the low temperature side and the tangent line (tangent line 2) was defined as the liquidus temperature.

From the obtained measurement results, the absolute value of the difference between the solidus temperature of the solder particles and the liquidus temperature of the solder particles was calculated.

(2) Content of tin, bismuth, and indium in 100% by weight of metal contained in solder particles. Measurement was performed using a spectroscopic analyzer (“ICP-AES” manufactured by Horiba, Ltd.).

(3) Viscosity of conductive material at solidus temperature of solder particles (ηsp)
Using the obtained conductive material, the viscosity (ηsp) of the conductive material at the solidus temperature of the solder particles was measured. The viscosity (ηsp) of the conductive material at the solidus temperature of the solder particles was measured using STRESSTECH (manufactured by REOLOGICA) 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. (However, if the solidus temperature of the solder particles exceeds 200°C, the upper temperature limit is set to the solidus temperature of the solder particles.) Measurement was performed under the following conditions.

(4) Accuracy of placement of solder on electrodes In the obtained connection structure, the first electrode and the second electrode face each other in the stacking direction of the first electrode, the connection part, and the second electrode. When looking at the part, the ratio X of the area where the solder part in the connection part is arranged to 100% of the area of the part where the first electrode and the second electrode face each other was evaluated. 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]
〇〇〇: Proportion X is 90% or more 〇〇: Proportion X is 80% or more and less than 90% 〇: Proportion

(5) Continuity reliability between upper and lower electrodes In the obtained connected structures (n=15 pieces), the connection resistance per connection point between the upper and lower electrodes was measured using a four-terminal method. The average value of connection resistance was calculated. Note that from the relationship of voltage=current×resistance, the connection resistance can be determined by measuring the voltage when a constant current is passed. Continuity reliability was judged based on the following criteria.

[Criteria for determining continuity reliability]
〇〇〇: Average value of connection resistance is 50mΩ or less 〇〇: Average value of connection resistance is more than 50mΩ and less than 70mΩ 〇: Average value of connection resistance is more than 70mΩ and less than 100mΩ ×: Average value of connection resistance is more than 100mΩ , or there is a poor connection.

The results are shown in Tables 1 to 3 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 particles 11B...Thermosetting component

Claims (12)

Contains a thermosetting component and solder particles,
The absolute value of the difference between the solidus temperature of the solder particles and the liquidus temperature of the solder particles is 5° C. or more,
A conductive material in which the content of the solder particles is 15% by weight or more based on 100% by weight of the conductive material. The conductive material according to claim 1, wherein the conductive material has a viscosity of 0.1 Pa·s or more and 50 Pa·s or less at the solidus temperature of the solder particles. The conductive material according to claim 1 or 2, wherein the solder particles contain bismuth, indium, silver, copper, or tin. The conductive material according to claim 3, wherein the content of bismuth is 1% by weight or more and 58% by weight or less in 100% by weight of metal contained in the solder particles. The conductive material according to claim 3 or 4, wherein the content of indium is 1% by weight or more and 52% by weight or less in 100% by weight of metal contained in the solder particles. The conductive material according to any one of claims 1 to 5, wherein the solder particles have a solidus temperature of 115°C or more and 220°C or less. The conductive material according to any one of claims 1 to 6, wherein the solder particles have a particle size of 0.01 μm or more and 30 μm or less. The conductive material according to any one of claims 1 to 7, 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 8,
A connection structure in which the first electrode and the second electrode are electrically connected by a solder part in the connection part. 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 are 10. The connection structure according to claim 9, wherein the solder part in the connection part is disposed on 50% or more of 100% of the area of the part facing the second electrode. using the conductive material according to any one of claims 1 to 8, disposing the conductive material on the surface of a first connection target member having a first electrode on the surface;
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 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 liquidus temperature of the solder particles. and a step of electrically connecting the first electrode and the second electrode with a solder part in the connecting part. 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 are 12. The method for manufacturing a connected structure according to claim 11, wherein the solder part in the connecting part is disposed in 50% or more of the 100% area of the part facing the second electrode. .

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