CN113994438A

CN113994438A - Conductive material, connection structure, and method for manufacturing connection structure

Info

Publication number: CN113994438A
Application number: CN202080045229.0A
Authority: CN
Inventors: 山中雄太; 辻井美香; 定永周治郎
Original assignee: Sekisui Chemical Co Ltd
Current assignee: Sekisui Chemical Co Ltd
Priority date: 2019-06-20
Filing date: 2020-06-12
Publication date: 2022-01-28
Also published as: TW202111732A; WO2020255874A1; KR20220019708A; JPWO2020255874A1

Abstract

Provided is a conductive material which can continuously perform an arrangement step such as printing and can efficiently arrange solder on an electrode. The conductive material according to the present invention is a conductive material comprising a thermosetting component, a plurality of solder particles and a flux, wherein the solder particles have an average particle diameter of less than 10 [ mu ] m, and the solder particles have an acid value of 0.3mgKOH/g or more and 3mgKOH/g or less.

Description

Conductive material, connection structure, and method for manufacturing connection structure

Technical Field

The present invention relates to a conductive material containing solder particles. The present invention also relates to a connection structure using the conductive material and a method for manufacturing the connection structure.

Background

Solder pastes containing a large amount of solder are known.

Further, an anisotropic conductive material containing a larger amount of binder resin than solder paste is also widely known. Examples of the anisotropic conductive material include an anisotropic conductive paste and an anisotropic conductive film. In the anisotropic conductive material, conductive particles are dispersed in a binder resin.

The anisotropic conductive material is used to obtain various connection structures. Examples of the connection by the anisotropic conductive material include connection between a flexible printed circuit board and a glass substrate (fog (fi lm on glass)), connection between a semiconductor chip and a flexible printed circuit board (cof (chip on film)), connection between a semiconductor chip and a glass substrate (cog (chip on glass)), and connection between a flexible printed circuit board and a glass epoxy substrate (fob (film on board)).

For example, when the electrode of the flexible printed circuit board and the electrode of the glass epoxy substrate are electrically connected to each other through the anisotropic conductive material, the anisotropic conductive material containing conductive particles is disposed on the glass epoxy substrate. Next, the flexible printed circuit board is stacked and heated and pressed. In this way, the anisotropic conductive material is cured, and the electrodes are electrically connected via the conductive particles, thereby obtaining a connection structure.

Patent documents

1 and 2 listed below describe materials that can be used for the anisotropic conductive material.

Patent document 1 listed below discloses a flux for solder paste containing a thickener, a solvent, and a thixotropic agent. The flux for paste has an acid value of 100mgKOH/g or less, a reduction rate of 80 mass% or more at 300 ℃ in thermogravimetric measurement, a viscosity of 0.5 pas or more, and an adhesive force of 1.0N or more.

Patent document 2 discloses a solder composition containing solder powder and flux. In the solder composition, the flux contains: a rosin resin having a softening point of 110 ℃ or lower and an acid value of 140mgK OH/g or higher, a rosin ester compound having a softening point of 110 ℃ or lower and an acid value of 5mgKOH/g or lower, and a solvent. The acid value of the flux is 5mgKOH/g or more and 70mgKOH/g or less.

Documents of the prior art

Patent document

Patent document 1: WO2019/022193A1

Patent document 2: japanese patent laid-open publication No. 2013-193097

Disclosure of Invention

Technical problem to be solved by the invention

When the conductive connection is performed using a conductive material containing solder particles, the upper plurality of electrodes and the lower plurality of electrodes are electrically connected, thereby performing the conductive connection. The solder particles are preferably arranged between the upper and lower electrodes, and are preferably not arranged between the adjacent electrodes in the lateral direction. Preferably, the electrodes in adjacent lateral directions are not electrically connected.

Generally, a conductive material containing solder particles is disposed at a specific position on a substrate by printing such as screen printing, and then heated by reflow or the like. When the conductive material is heated to a temperature higher than the melting point of the solder particles, the solder particles melt, and the solder is aggregated between the electrodes, thereby electrically connecting the upper and lower electrodes.

In the conventional conductive material, if printing such as screen printing is repeated, the viscosity of the conductive material at the time of printing is sometimes lowered, the screen penetration amount is increased, and bleeding of the conductive material occurs. Further, in the conventional conductive material, if printing such as screen printing is repeated, the viscosity of the conductive material at the time of printing sometimes increases, and the conductive material blocks the mesh, resulting in the occurrence of whitening of the conductive material (かすれ). As described above, in the conventional conductive material, if printing such as screen printing is continuously performed, bleeding, blooming, and the like of the conductive material occur, and thus it is difficult to continuously perform printing such as screen printing.

Further, in the conventional conductive material, the moving speed of the solder particles to the electrodes (wires) is slow, and therefore the solder cannot be efficiently arranged between the upper and lower electrodes to be connected. If the solder cannot be sufficiently condensed between the electrodes in the vertical direction to be connected, solder particles or the like are separated from the solder between the electrodes in the vertical direction as solder balls or the like and remain between the electrodes in the horizontal direction to which connection is prohibited. As a result, the conduction reliability between electrodes to be connected and the insulation reliability between adjacent electrodes to which connection is prohibited cannot be sufficiently improved.

In recent years, as electronic devices have been miniaturized, parts mounted in the electronic devices have also been miniaturized, and with such a trend, it has been necessary to reduce the average particle diameter of solder particles contained in a conductive material. However, if the average particle diameter of the solder particles is made small, the viscosity of the conductive material tends to increase, and there are cases where the arrangement step such as printing cannot be continuously performed, or the solder cannot be efficiently arranged on the electrodes.

The invention aims to provide a conductive material which can continuously perform an arrangement process such as printing and can efficiently arrange solder on an electrode. Another object of the present invention is to provide a connection structure using the conductive material and a method for manufacturing the connection structure.

Means for solving the problems

According to a broad aspect of the present invention, there is provided a conductive material comprising a thermosetting component, a plurality of solder particles and a flux, wherein the solder particles have an average particle diameter of less than 10 μm, and the solder particles have an acid value of 0.3mgKOH/g or more and 3mgKOH/g or less.

In a specific aspect of the conductive material according to the present invention, the conductive material stored in a frozen state is thawed, and the viscosity of the conductive material at 25 ℃ is 100Pa · s or more and 200Pa · s or less.

In a specific embodiment of the conductive material according to the present invention, the viscosity of the conductive material after the conductive material is thawed and stored at 25 ℃ and 50% RH for 24 hours is 100Pa · s or more and 300Pa · s or less at 25 ℃.

In a specific embodiment of the conductive material according to the present invention, the thermosetting component contains an epoxy compound.

In a specific aspect of the conductive material according to the present invention, the solder particles have an average particle diameter of less than 1 μm.

In a specific 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, there is provided a connection structure comprising: the first connection target member includes a1 st electrode on a surface thereof, a 2 nd connection target member including a 2 nd electrode on a surface thereof, and a connection portion connecting the 1 st connection target member and the 2 nd connection target member, the connection portion is made of the conductive material, and the 1 st electrode and the 2 nd electrode are electrically connected by a solder portion in the connection portion.

According to an aspect of the present invention, there is provided a method of manufacturing a connection structure, including: disposing the conductive material on a surface of a1 st connection target member having a1 st electrode on a surface thereof, using the conductive material; disposing a 2 nd connection target member having a 2 nd electrode on a surface of the conductive material opposite to the 1 st connection target member side so that the 1 st electrode and the 2 nd electrode face each other; and a step of forming a connection portion for connecting the 1 st connection target component and the 2 nd connection target component by using the conductive material by heating the conductive material to a melting point of the solder particles or higher, and electrically connecting the 1 st electrode and the 2 nd electrode by a solder portion in the connection portion.

ADVANTAGEOUS EFFECTS OF INVENTION

The conductive material according to the present invention contains a thermosetting component, a plurality of solder particles, and a flux. In the conductive material according to the present invention, the solder particles have an average particle diameter of less than 10 μm, and the acid value of the solder particles is 0.3mgKOH/g or more and 3mgKOH/g or less. The conductive material according to the present invention, having the above-described configuration, can continuously perform a placement step such as printing, and can efficiently place solder on an electrode.

Drawings

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

Fig. 2(a) to (c) are sectional views for explaining respective steps of an example of a method for manufacturing a connection structure using a conductive material according to an embodiment of the present invention.

Fig. 3 is a cross-sectional view showing a modification of the connection structure.

Detailed description of the invention

Hereinafter, the detailed description of the present invention will be described.

(conductive Material)

The conductive material according to the present invention contains a thermosetting component, a plurality of solder particles, and a flux. In the conductive material according to the present invention, the solder particles have an average particle diameter of less than 10 μm, and the acid value of the solder particles is 0.3mgKOH/g or more and 3mgKOH/g or less.

Since the conductive material according to the present invention has the above-described configuration, the placement process such as printing can be continuously performed, and the solder can be efficiently placed on the electrode. In the conductive material according to the present invention, even when the average particle diameter of the solder particles is small, the solder can be efficiently arranged on the electrode while the arrangement process such as printing can be continuously performed. As a result, the reliability of conduction between the upper and lower electrodes to be connected can be effectively improved, and the reliability of connection between the solder portion and the electrode can be further improved. In particular, the conductive material according to the present invention can be printed by screen printing or the like continuously and favorably.

In the

patent documents

1 and 2, only the control of the acid value of the flux is found. Conventionally, there has been no recognition that printing can be continuously performed and solder can be efficiently arranged on an electrode by setting the acid value of solder particles within a specific range.

The present inventors have found that: by using a conductive material in which the acid value of the solder particles is within a specific range, the arrangement step such as printing can be continuously performed, and the solder can be efficiently arranged on the electrode.

Further, the conductive material according to the present invention can suppress the generation of voids at the time of bonding due to the above-described configuration.

Further, in the present invention, the misalignment between the electrodes can be prevented. In the present invention, when the 2 nd connection object member is superposed on the 1 st connection object member having the conductive material arranged on the upper surface thereof, even in a state where the alignment of the electrode of the 1 st connection object member and the electrode of the 2 nd connection object member is deviated, the deviation can be corrected and the electrodes can be connected to each other (self-alignment effect).

From the viewpoint of more efficiently disposing the solder on the electrode, the conductive material is preferably in a liquid state at 25 ℃, and is preferably a conductive paste. The conductive material is preferably a conductive paste at 25 ℃.

From the viewpoint of more efficiently disposing solder on the electrode, the viscosity (η 25) at 25 ℃ of the conductive material as produced is preferably 100Pa · s or more, more preferably 120Pa · s or more, further preferably 140Pa · s or more, preferably 200Pa · s or less, and more preferably 180Pa · s or less. The viscosity (. eta.25) can be suitably adjusted depending on the kind and the amount of the compounding ingredients.

The frozen and stored conductive material is thawed, and the viscosity (η a) at 25 ℃ of the conductive material immediately after reaching 25 ℃ is preferably 100Pa · s or more, more preferably 120Pa · s or more, preferably 200Pa · s or less, and more preferably 180Pa · s or less. If the viscosity (η a) is not lower than the lower limit and not higher than the upper limit, the solder can be more efficiently disposed on the electrodes, and the reliability of conduction between the upper and lower electrodes to be connected can be more effectively improved. The viscosity (. eta.A) can be adjusted as appropriate depending on the kind and the amount of the compounding ingredients.

The viscosity (η B) of the conductive material at 25 ℃ after thawing the conductive material subjected to freezing storage and storing the conductive material at 25 ℃ and 50% RH for 24 hours is preferably 100Pa · s or more, more preferably 120Pa · s or more, preferably 300Pa · s or less, and more preferably 200Pa · s or less. If the viscosity (η B) is not lower than the lower limit and not higher than the upper limit, the solder can be more efficiently disposed on the electrodes, and the reliability of conduction between the upper and lower electrodes to be connected can be more effectively improved. The viscosity (. eta.B) can be adjusted as appropriate depending on the kind and the amount of the compounding ingredients.

The ratio of the viscosity (η B) to the viscosity (η a) (viscosity (η B)/viscosity (η a)) is preferably 0.8 or more, more preferably 1.0 or more, preferably 2.0 or less, and more preferably 1.5 or less. If the ratio (viscosity (η B)/viscosity (η a)) is not less than the lower limit and not more than the upper limit, solder can be more efficiently disposed on the electrodes, and the reliability of conduction between the upper and lower electrodes to be connected can be more effectively improved.

The viscosity (. eta.25), the viscosity (. eta.A) and the viscosity (. eta.B) can be measured at 25 ℃ and 5rpm, for example, using an E-type viscometer ("TVE 22L", manufactured by Toyobo industries, Ltd.).

In the present specification, the conductive material for measuring the viscosity is stored in a frozen state at-40 ℃ for 7 days. On the other hand, the conditions for the frozen storage in actual use of the conductive material are not particularly limited. The temperature of the frozen storage of the electrically conductive material in actual use is not particularly limited, and may be less than 0 ℃. The temperature of the frozen storage of the conductive material in actual use may be-10 ℃ or lower, may be-20 ℃ or lower, or may be-40 ℃ or lower. The time for freezing storage of the conductive material in actual use is not particularly limited, and may be 180 days or less. The time for the frozen storage may be 30 days or more, 60 days or more, 90 days or more, or 120 days or more.

In the present specification, the thawing conditions of the conductive material for measuring the viscosity are conditions under which the conductive material is stored at 25 ℃. On the other hand, a method for thawing the frozen and stored conductive material in actual use is not particularly limited. As a method for thawing a conductive material stored frozen when it is actually used, there are a method for thawing at room temperature, a method for thawing under refrigeration, and a method for thawing under heating, and the like. The room temperature condition is preferably 20 ℃ to 25 ℃. The refrigeration condition is preferably more than 0 ℃ and 10 ℃ or less. The heating conditions are preferably 30 ℃ to 35 ℃.

The 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. The conductive material is preferably a conductive paste in view of more efficiently disposing solder on the electrode. The conductive material is suitable for electrical connection of the electrodes. The conductive material is preferably a circuit connecting material.

Hereinafter, each component contained in the conductive material will be explained. In the present specification, "(meth) acrylic acid" means one or both of "acrylic acid" and "methacrylic acid".

(solder particle)

The conductive material includes solder particles. The central portion and the outer surface of the solder particle are both formed of solder. The solder particles are particles in which the central portion and the outer surface are solder. If conductive particles having base particles made of a material other than solder and solder portions arranged on the surfaces of the base particles are used in place of the solder particles, the conductive particles are less likely to aggregate on the electrodes. Further, since the conductive particles have low solder bondability with each other, the conductive particles moving to the electrodes tend to move to the outside of the electrodes, and the effect of suppressing the displacement between the electrodes tends to be low.

The solder particles have an acid value of 0.3mgKOH/g to 3mgKOH/g from the viewpoint of continuously performing a placement step such as printing and the like and from the viewpoint of efficiently placing solder on electrodes to improve the reliability of conduction between upper and lower electrodes to be connected.

The acid value of the solder particles is preferably 0.5mgKOH/g or more, more preferably 0.7mgKOH/g or more, preferably 2.5mgKOH/g or less, and more preferably 2.0mgKOH/g or less. If the acid value of the solder particles is not less than the lower limit and not more than the upper limit, the arrangement process such as printing can be performed continuously and preferably, the solder can be arranged on the electrodes more efficiently, and the conduction reliability between the upper and lower electrodes to be connected can be further improved.

The acid value of the solder particles can be determined as follows.

1g of solder particles was added to 10g of water, and dispersed for 1 minute by ultrasonic waves. Then, titration was carried out with 0.1mol/L ethanol solution of potassium hydroxide using phenolphthalein as an indicator.

It is considered that the acid value of the solder particles varies depending on the properties of the surfaces of the solder particles. Further, it is considered that the difference in the properties of the solder particle surface causes the difference in the continuous printability and the arrangement accuracy of the solder. If the acid value of the solder particles is less than 0.3mgKOH/g, it is considered that the solder particles are less likely to be aggregated on the electrodes, and the arrangement accuracy is deteriorated. If the acid value of the solder particles is higher than 3mgKOH/g, it is considered that a large number of acidic groups are present on the surface of the solder particles, and the acidic groups react with the resin in the conductive paste to increase the viscosity, thereby deteriorating the printability and the arrangement accuracy.

The solder is preferably a metal (low-melting metal) having a melting point of 450 ℃ or lower. The solder particles are preferably metal particles having a melting point of 450 ℃ or lower (low-melting-point metal particles). The low-melting metal particles are particles containing a low-melting metal. The low melting point metal is a metal having a melting point of 450 ℃ or lower. From the viewpoint of suppressing thermal degradation during production of the connection structure, the melting point of the low-melting-point metal is preferably 400 ℃ or lower, more preferably 350 ℃ or lower, and still more preferably 300 ℃ or lower. The solder particles are preferably low melting point solder with a melting point less than 250 ℃.

From the viewpoint of more effectively exhibiting the effects of the present invention, the melting point of the solder particles is preferably 200 ℃ or higher, more preferably 210 ℃ or higher, and still more preferably 220 ℃ or higher.

The melting point of the solder particles can be determined by Differential Scanning Calorimetry (DSC). Examples of the Differential Scanning Calorimetry (DSC) apparatus include "EXSTAR DSC 7020" manufactured by SII corporation.

Further, the solder particles preferably contain tin. The content of tin in 100 wt% of the metal contained in the solder particles is preferably 30 wt% or more, more preferably 40 wt% or more, further preferably 70 wt% or more, and particularly preferably 90 wt% or more. If the tin content in the solder particles is not less than the lower limit, the connection reliability between the solder portion and the electrode is further improved.

The content of tin can be measured using a high-frequency inductively coupled plasma emission spectrometer ("ICP-AES", horiba ltd.) or a fluorescent X-ray spectrometer ("EDX-800 HS", shimadzu ltd.).

By using the solder particles, the solder is melted and joined to the electrodes, and the solder portion conducts electricity between the electrodes. For example, since the solder portion and the electrode easily make surface contact rather than point contact, the connection resistance is reduced. Further, by using the solder particles, the bonding strength between the solder portion and the electrode is improved, and as a result, the solder portion and the electrode are less likely to be peeled off, and the conduction reliability and the connection reliability are further improved.

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, because of excellent wettability to an electrode. The low melting point metal is more preferably a tin-bismuth alloy, or a tin-indium alloy.

The solder particles are, according to JIS Z3001: the filler metal having a liquidus of 450 ℃ or less is preferable for the welding. Examples of the composition of the solder particles include a metal composition containing zinc, gold, silver, lead, copper, tin, bismuth, indium, and the like. Preferably, the alloy is a low-melting Lead-free tin-indium system (117 ℃ eutectic) or a tin-bismuth system (139 ℃ eutectic). That is, the solder particles are preferably lead-free, and preferably contain tin and indium, or tin and bismuth.

From the viewpoint of further effectively exerting the effect of the present invention, the solder particles preferably contain tin and silver, or tin and copper, and more preferably tin, silver, and copper.

In order to further improve the bonding strength between the solder portion and the electrode, the solder particles may include metals such as nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth, manganese, chromium, molybdenum, and palladium. In addition, from the viewpoint of further improving the bonding strength between the solder portion and the electrode, the solder particles preferably contain nickel, copper, antimony, aluminum, or zinc. From the viewpoint of further improving the bonding strength between the solder portion and the electrode, the content of these metals for improving the bonding strength is preferably 0.0001 wt% or more, and preferably 1 wt% or less, out of 100 wt% of the metals contained in the solder particles.

The solder particles have an average particle diameter of less than 10 μm in view of a disposing step such as printing and in view of disposing solder on the electrodes more efficiently and improving the reliability of conduction between upper and lower electrodes to be connected. In the present invention, the effects of the present invention can be effectively exhibited even if the average particle diameter of the solder particles is small.

The solder particles preferably have an average particle diameter of 0.1 μm or more, more preferably 2 μm or more, preferably 8 μm or less, and more preferably 5 μm or less. If the average particle diameter of the solder particles is not less than the lower limit and not more than the upper limit, the printing can be further continuously performed, and the solder can be further efficiently arranged on the electrodes, thereby improving the conduction reliability between the upper and lower electrodes to be connected. The solder particles may have an average particle diameter of 2 μm or less, 1 μm or less, or less than 1 μm. In the present invention, the effects of the present invention can be effectively exhibited even if the average particle diameter of the solder particles is considerably small.

The average particle diameter of the solder particles is preferably a number average particle diameter. The average particle size of the solder particles can be determined, for example, by observing 50 arbitrary solder particles with an electron microscope or an optical microscope, calculating the average particle size of each solder particle, or performing laser diffraction type particle size distribution measurement.

In addition, as a method for adjusting the average particle diameter of the solder particles to the preferable range, a method of pulverizing the solder particles by an air mill or the like, a sieving method using a sieve or the like, and the like can be mentioned.

The coefficient of variation (CV value) of the particle diameter of the solder particles is preferably 5% or more, more preferably 10% or more, preferably 40% or less, and more preferably 30% or less. If the coefficient of variation of the particle diameter of the solder particles is not less than the lower limit and not more than the upper limit, the solder can be more efficiently arranged on the electrode. However, the CV value of the particle diameter of the solder particles may be less than 5%.

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

CV value (%) - (ρ/Dn) × 100

ρ: standard deviation of particle size of solder particles

Dn: average value of particle diameter of solder particles

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

The content of the solder particles in 100 wt% of the conductive material is preferably 40 wt% or more, more preferably 45 wt% or more, further preferably 50 wt% or more, particularly preferably 55 wt% or more, preferably 90 wt% or less, more preferably 85 wt% or less, further preferably 80 wt% or less. If the content of the solder particles is not less than the lower limit and not more than the upper limit, the solder can be more efficiently arranged on the electrodes, a large amount of solder can be easily arranged between the electrodes, and the conduction reliability can be more effectively improved. From the viewpoint of further improving the conduction reliability, the content of the solder particles is preferably large.

(thermosetting component)

The conductive material according to the present invention contains a thermosetting component. The conductive material may contain a thermosetting compound and a thermosetting agent as thermosetting components. In order to further favorably cure the conductive material, the conductive material preferably contains a thermosetting compound and a thermosetting agent as thermosetting components. In order to further favorably cure the conductive material, the conductive material preferably contains a curing accelerator as a thermosetting component.

(thermosetting component: thermosetting compound)

The conductive material according to the present invention preferably contains a thermosetting compound. The thermosetting compound is a compound that can be cured by heating.

The thermosetting compound is not particularly limited. Examples of the thermosetting compound include an oxetane compound, an epoxy compound, an episulfide compound, (meth) acrylic acid compound, a phenol compound, an amino compound, an unsaturated polyester compound, a polyurethane compound, a polysiloxane compound, and a polyimide compound. The thermosetting compound may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

From the viewpoint of further improving the curability and viscosity of the conductive material and further improving the conduction reliability, the thermosetting compound preferably contains an epoxy compound or an episulfide compound, more preferably contains an epoxy compound, still more preferably an epoxy compound or an episulfide compound, and particularly preferably an epoxy compound. The thermosetting component preferably contains an epoxy compound or an episulfide compound, and more preferably contains an epoxy compound. The conductive material preferably contains an epoxy compound or an episulfide compound, and more preferably contains an epoxy compound.

The epoxy compound is a compound having at least 1 epoxy group. Examples of the epoxy compound include a bisphenol a type epoxy compound, a bisphenol F type epoxy compound, a bisphenol S type epoxy compound, a phenol novolac type epoxy compound, a biphenyl novolac type epoxy compound, a bisphenol type epoxy compound, a naphthalene type epoxy compound, a fluorene type epoxy compound, a phenol aralkyl type epoxy compound, a naphthol aralkyl type epoxy compound, a dicyclopentadiene type epoxy compound, an anthracene type epoxy compound, an epoxy compound having an adamantane skeleton, an epoxy compound having a tricyclodecane skeleton, a naphthyl ether type epoxy compound, and an epoxy compound having a triazine core in the skeleton. The epoxy compound may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The epoxy compound is liquid or solid at normal temperature (25 ℃), and if the epoxy compound is solid at normal temperature, the melting temperature of the epoxy compound is preferably not higher than the melting point of the solder particles. By using the preferable epoxy compound, the viscosity is high in the stage of bonding the members to be connected, and when acceleration is applied by an impact such as transportation, the misalignment between the 1 st member to be connected and the 2 nd member to be connected can be suppressed. Further, the viscosity of the conductive material can be greatly reduced by heat at the time of curing, and the aggregation of the solder at the time of conductive connection can be efficiently performed.

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

Examples of the thermosetting compound having a polyether skeleton include compounds having glycidyl ether groups at both ends of an alkyl chain having 3 to 12 carbon atoms; and a polyether epoxy compound having a polyether skeleton having 2 to 4 carbon atoms and having 2 to 10 structural units in which the polyether skeleton is continuously bonded.

The thermosetting compound preferably contains a thermosetting compound having an isocyanuric skeleton from the viewpoint of further effectively improving the heat resistance of the cured product.

The thermosetting compound having an isocyanuric skeleton includes triisocyanurate type epoxy compounds, and TEPIC series (TEPIC-G, TEPIC-S, TEPIC-SS, TEPIC-HP, TEPIC-L, TEPIC-PAS, TEPIC-VL, TEPIC-UC) manufactured by Nissan chemical industries, and the like.

From the viewpoint of more efficiently disposing solder on the electrodes, from the viewpoint of more effectively improving the conduction reliability between the upper and lower electrodes to be connected, and from the viewpoint of more effectively suppressing discoloration of the thermosetting compound, the thermosetting compound preferably has high heat resistance, and more preferably a novolac-type epoxy compound. The novolak type epoxy compound has relatively high heat resistance.

The content of the thermosetting compound is preferably 5% by weight or more, more preferably 8% by weight or more, further preferably 10% by weight or more, preferably 99% by weight or less, more preferably 90% by weight or less, further preferably 80% by weight or less, and particularly preferably 70% by weight or less, in 100% by weight of the conductive material. If the content of the thermosetting compound is not less than the lower limit and not more than the upper limit, the solder can be more efficiently arranged on the electrode, the insulation reliability between the electrodes can be more effectively improved, and the conduction reliability between the electrodes can be more effectively improved. From the viewpoint of further effectively improving the impact resistance, the content of the thermosetting compound is preferably large.

The content of the epoxy compound in 100 wt% of the conductive material is preferably 5 wt% or more, more preferably 8 wt% or more, further preferably 10 wt% or more, preferably 99 wt% or less, more preferably 90 wt% or less, further preferably 80 wt% or less, and particularly preferably 70 wt% or less. If the content of the epoxy compound is not less than the lower limit and not more than the upper limit, the solder can be more efficiently arranged on the electrode, the insulation reliability between the electrodes can be more effectively improved, and the conduction reliability between the electrodes can be more effectively improved. From the viewpoint of further improving impact resistance, the content of the epoxy compound is preferably large.

(thermosetting component: thermosetting agent)

The conductive material may include a thermal curing agent. The conductive material may contain a thermosetting agent together with the thermosetting compound. The thermosetting agent thermally cures the thermosetting compound.

The thermal curing agent is not particularly limited. Examples of the thermal curing agent include an imidazole curing agent, a phenol curing agent, a thiol curing agent, an amine curing agent, an acid anhydride curing agent, a thermal cation curing agent, and a thermal radical initiator. The heat-curing agent may be used in 1 type alone, or may be used in combination of 2 or more types.

The thermal curing agent is preferably an imidazole curing agent, a thiol curing agent, or an amine curing agent from the viewpoint of enabling the conductive material to be cured more rapidly at a low temperature. In addition, the thermosetting agent is preferably a latent curing agent in view of improving storage stability when the thermosetting compound and the thermosetting agent are mixed. The latent curing agent is preferably a latent imidazole curing agent, a latent thiol curing agent, or a latent amine curing agent. The heat-curing agent may be coated with a polymer such as a polyurethane resin or a polyester resin.

The 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 an addition product of 2, 4-diamino-6- [2 '-methylimidazolyl- (1') ] -ethyl-s-triazine isocyanuric acid, 2-phenyl-4, 5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4-benzyl-5-hydroxymethylimidazole, and mixtures thereof, And imidazole compounds in which the 5-position hydrogen of 1H-imidazole in 2-p-tolyl-4-methyl-5-hydroxymethylimidazole, 2-m-tolyl-4, 5-dihydroxymethylimidazole, 2-p-tolyl-4, 5-dihydroxymethylimidazole is substituted with a hydroxymethyl group and the 2-position hydrogen is substituted with a phenyl group or a tolyl group.

The thiol curing agent is not particularly limited. Examples of the thiol curing agent include trimethylolpropane tri-3-mercaptopropionate, pentaerythritol tetra-3-mercaptopropionate, and dipentaerythritol hexa-3-mercaptopropionate.

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

The acid anhydride curing agent is not particularly limited, and any acid anhydride can be widely used as long as it is used as a curing agent for a thermosetting compound such as an epoxy compound. Examples of the acid anhydride curing agent include 2-functional acid anhydride curing agents such as phthalic anhydride, tetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylbutenyl tetrahydrophthalic anhydride, phthalic anhydride derivative anhydrides, maleic anhydride, nadic anhydride, methylnadic anhydride, glutaric anhydride, succinic anhydride, glycerol bis (anhydrous) trimellitic monoacetate, and ethylene glycol bis (trimellitic anhydride), 3-functional acid anhydride curing agents such as trimellitic anhydride, and 4-or more-functional acid anhydride curing agents such as pyromellitic anhydride, benzophenone tetracarboxylic anhydride, methylcyclohexene tetracarboxylic anhydride, and polyazelaic anhydride.

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

The thermal radical initiator is not particularly limited. Examples of the thermal radical initiator include azo compounds and organic peroxides. Examples of the azo compound include Azobisisobutyronitrile (AIBN). 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 ℃ or higher, more preferably 70 ℃ or higher, further preferably 80 ℃ or higher, preferably 250 ℃ or lower, more preferably 200 ℃ or lower, further preferably 150 ℃ or lower, and particularly preferably 140 ℃ or lower. If the reaction start temperature of the thermosetting agent is not lower than the lower limit and not higher than the upper limit, the solder can be more efficiently arranged on the electrode. The reaction start temperature of the thermosetting agent is particularly preferably 80 ℃ or higher and 140 ℃ or lower from the viewpoint of more efficiently disposing the solder on the electrodes and from the viewpoint of more effectively improving the conduction reliability between the upper and lower electrodes to be connected.

The reaction initiation temperature of the thermosetting agent is a temperature at which an exothermic peak starts to increase in DSC. Examples of the DSC device include "EXSTAR DSC 7020" manufactured by SII corporation.

The content of the thermosetting agent is not particularly limited. The content of the thermosetting agent is preferably 0.01 part by weight or more, more preferably 1 part by weight or more, preferably 200 parts by weight or less, more preferably 100 parts by weight or less, and further preferably 75 parts by weight or less, based on 100 parts by weight of the thermosetting compound. If the content of the thermosetting agent is not less than the lower limit, the conductive material is easily cured sufficiently. If the content of the thermosetting agent is not more than the upper limit, the remaining thermosetting agent not involved in curing after curing is less likely to remain, and the heat resistance of the cured product is further improved.

(thermosetting component: curing Accelerator)

The conductive material may include a curing accelerator. The curing accelerator is not particularly limited. The curing accelerator preferably functions as a curing catalyst in the reaction between the thermosetting compound and the thermal curing agent. The curing accelerator preferably functions as a curing catalyst in the reaction with the thermosetting compound. The curing accelerator may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

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

The phosphonium salt is not particularly limited. Examples of the phosphonium salt include tetra-n-butylphosphonium bromide, tetra-n-butylphosphonium O-O diethyldithiophosphoric acid, methyltributylphosphonium dimethylphosphate, tetra-n-butylphosphonium benzotriazole, tetra-n-butylphosphonium tetrafluoroborate, and tetra-n-butylphosphonium tetraphenylborate.

The content of the curing accelerator can be suitably selected so that the thermosetting compound is cured well. The content of the curing accelerator is preferably 0.5 parts by weight or more, more preferably 0.8 parts by weight or more, preferably 10 parts by weight or less, and more preferably 8 parts by weight or less, based on 100 parts by weight of the thermosetting compound. If the content of the curing accelerator is not less than the lower limit and not more than the upper limit, the thermosetting compound can be cured satisfactorily. Further, if the content of the curing accelerator is not less than the lower limit and not more than the upper limit, the solder can be more efficiently arranged on the electrodes, and the reliability of conduction between the upper and lower electrodes to be connected can be more effectively improved.

(flux)

The conductive material includes a flux. By using the flux, the solder can be more efficiently arranged on the electrode. The flux is not particularly limited. As the flux, flux generally used in solder bonding or the like can be used.

Examples of the flux 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 rosin. The flux may be used in 1 kind alone, or may be used in combination of 2 or more kinds.

Examples of the molten salt include ammonium chloride. Examples of the organic acid include lactic acid, citric acid, stearic acid, glutamic acid, glutaric acid, and the like. Examples of the rosin include activated rosin and non-activated rosin. The flux is preferably an organic acid or rosin having 2 or more carboxyl groups. The soldering flux can be organic acid with more than 2 carboxyl groups, and can also be rosin. By using an organic acid or rosin having 2 or more carboxyl groups, the conduction reliability between electrodes is further improved.

Examples of the organic acid having 2 or more carboxyl groups include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacic acid.

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

The rosin is rosin containing abietic acid as main component. Examples of the rosin include rosin acids and acrylic acid-modified rosins. The flux is preferably rosin, more preferably abietic acid. By using the preferred flux, the conduction reliability between the electrodes is further improved.

The activation temperature (melting point) of the flux is preferably 50 ℃ or higher, more preferably 70 ℃ or higher, further preferably 80 ℃ or higher, preferably 200 ℃ or lower, more preferably 190 ℃ or lower, further preferably 160 ℃ or lower, further preferably 150 ℃ or lower, and particularly preferably 140 ℃ or lower. If the active temperature of the flux is not lower than the lower limit and not higher than the upper limit, the flux effect is more effectively exhibited, and the solder can be more efficiently arranged on the electrode.

The melting point of the flux can be determined by Differential Scanning Calorimetry (DSC). Examples of the Differential Scanning Calorimetry (DSC) apparatus include "EXSTAR DSC 7020" manufactured by SII corporation.

The boiling point of the flux is preferably 200 ℃ or lower.

From the viewpoint of more efficiently disposing solder on the electrode, the melting point of the flux is preferably higher than the reaction start temperature of the thermosetting agent, more preferably higher by 5 ℃ or more, and still more preferably higher by 10 ℃ or more.

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

The flux is preferably a flux that emits cations by heating. By using the flux which emits cations by heating, the solder can be more efficiently arranged on the electrode.

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

The flux is preferably a salt of an acid compound and an alkali compound from the viewpoint of more efficiently disposing solder on the electrode, the viewpoint of more effectively improving insulation reliability, and the viewpoint of more effectively improving conduction reliability.

The acid compound is preferably an organic compound having a carboxyl group. Examples of the acid compound 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, cyclic aliphatic carboxylic acids such as cyclohexylcarboxylic acid, 1, 4-cyclohexyldicarboxylic acid, aromatic carboxylic acids such as isophthalic acid, terephthalic acid, trimellitic acid, and ethylenediaminetetraacetic acid. The acid compound is preferably glutaric acid, cyclohexylcarboxylic acid, or adipic acid from the viewpoint of more efficiently disposing solder on the electrode, the viewpoint of more effectively improving insulation reliability, and the viewpoint of more effectively improving conduction reliability.

The base compound is preferably an organic compound having an amino group. Examples of the base compound 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-dimethylbenzylamine, imidazole compounds, and triazole compounds. The alkali compound is preferably benzylamine from the viewpoint of more efficiently disposing solder on the electrode, from the viewpoint of more effectively improving insulation reliability, and from the viewpoint of more effectively improving conduction reliability.

The content of the flux is preferably 0.5 wt% or more, preferably 30 wt% or less, and more preferably 25 wt% or less, based on 100 wt% of the conductive material. If the content of the flux is not less than the lower limit and not more than the upper limit, the oxide film is further difficult to form on the surfaces of the solder and the electrode, and the oxide film formed on the surfaces of the solder and the electrode can be further effectively removed.

(Filler)

The conductive material may include a filler. The filler can be an organic filler or an inorganic filler. The conductive material can further uniformly aggregate the solder over the entire electrode of the substrate by containing the filler. In addition, the conductive material can further uniformly disperse the solder particles in the conductive material by containing a filler.

The conductive material preferably does not contain the filler, or contains 5 wt% or less of the filler. In the case of using the thermosetting compound, the smaller the content of the filler, the more easily the solder particles move on the electrode.

The content of the filler is preferably 0 wt% (not contained) or more, preferably 5 wt% or less, more preferably 2 wt% or less, and further preferably 1 wt% or less, in 100 wt% of the conductive material. If the filler content is not less than the lower limit and not more than the upper limit, the solder can be more uniformly arranged on the electrode.

(other Components)

The conductive material may contain various additives such as fillers, extenders, softeners, plasticizers, thixotropic agents, leveling agents, polymerization catalysts, curing catalysts, colorants, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, slip agents, antistatic agents, and flame retardants, as needed.

(connection structure and method for manufacturing connection structure)

A connection structure according to the present invention includes a1 st connection object member having a1 st electrode on a surface thereof, a 2 nd connection object member having a 2 nd electrode on a surface thereof, and a connection portion for connecting the 1 st connection object member and the 2 nd connection object member. In the connection structure according to the present invention, the material of the connection portion is the conductive material. In the connection structure according to the present invention, the 1 st electrode and the 2 nd electrode are electrically connected by a solder portion in the connection portion.

The method for manufacturing a connection structure according to the present invention includes: and disposing the conductive material on a surface of a1 st connection target member having a1 st electrode on a surface thereof, using the conductive material. The method for manufacturing a connection structure according to the present invention includes: and disposing a 2 nd connection target member having a 2 nd electrode on a surface of the conductive material opposite to the 1 st connection target member so that the 1 st electrode and the 2 nd electrode face each other. The method for manufacturing a connection structure according to the present invention includes: and a step of forming a connection portion for connecting the 1 st connection target component and the 2 nd connection target component by using the conductive material by heating the conductive material to a melting point of the solder particles or higher, and electrically connecting the 1 st electrode and the 2 nd electrode by a solder portion in the connection portion.

In the connection structure and the method for manufacturing the connection structure according to the present invention, since the specific conductive material is used, the solder particles are easily gathered between the 1 st electrode and the 2 nd electrode, and the solder can be efficiently arranged on the electrode (wire). Further, a part of the solder is not easily arranged in the region (space) where no electrode is formed, and the amount of the solder arranged in the region where no electrode is formed can be greatly reduced. Therefore, the conduction reliability between the 1 st electrode and the 2 nd electrode can be improved. Further, electrical connection between horizontally adjacent electrodes that are prohibited from being connected can be prevented, and insulation reliability can be improved.

In addition, in order to further efficiently dispose solder on the electrodes and to greatly reduce the amount of solder disposed into the regions where the electrodes are not formed, it is preferable to use a conductive paste, not a conductive film, for the conductive material.

The thickness of the solder part between the electrodes is preferably 10 μm or more, more preferably 20 μm or more, preferably 100 μm or less, and more preferably 80 μm or less. The solder-wetting area on the surface of the electrode (the area in contact with the solder in 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 connection structure according to the present invention, it is preferable that the 2 nd connection object member is placed on the conductive material without applying pressure in the step of disposing the 2 nd connection object member and the step of forming the connection portion. In the method for manufacturing a connection structure according to the present invention, it is preferable that a pressurizing pressure exceeding the weight of the 2 nd connection object member is not applied to the conductive material in the step of disposing the 2 nd connection object member and the step of forming the connection portion. In these cases, the uniformity of the amount of solder can be further improved in the plurality of solder portions. Further, the thickness of the solder portion can be further effectively increased, and a large number of solder particles can be easily collected between the electrodes, so that a large number of solder particles can be further efficiently arranged on the electrodes (wires). Further, a part of the plurality of solder particles is less likely to be arranged in a region (space) where no electrode is formed, and the amount of solder arranged in the region where no electrode is formed can be further reduced. Therefore, the reliability of conduction between the electrodes can be further improved. Further, electrical connection between horizontally adjacent electrodes to which connection is prohibited can be further prevented, and insulation reliability can be further improved.

Further, if a conductive paste is used instead of the conductive film, the thickness of the connecting portion and the solder portion can be easily adjusted by the amount of application of the conductive paste. On the other hand, the conductive film has the following problems: in order to change or adjust the thickness of the connection portion, it is necessary to prepare conductive films having different thicknesses or to prepare conductive films having a specific thickness. In addition, the conductive film tends to be less likely to have a sufficiently lower melt viscosity than the conductive paste at the melting temperature of the solder particles, and to inhibit aggregation of the solder particles.

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

The connection structure 1 shown in fig. 1 includes: a1 st connection object member 2, a 2 nd connection object member 3, and a connection portion 4 for connecting the 1 st connection object member 2 and the 2 nd connection object member 3. The connection portion 4 is formed of the conductive material. In the present embodiment, the conductive material includes a thermosetting component, a plurality of solder particles, and a flux. The thermosetting component contains a thermosetting compound and a thermosetting agent. In this embodiment mode, a conductive paste is used as a conductive material.

The connection portion 4 has: a solder portion 4A in which a plurality of solder particles are polymerized and bonded to each other, and a cured product portion 4B in which a thermosetting component is thermally cured.

The 1 st connection target member 2 has a plurality of 1 st electrodes 2a on a surface (upper surface). The 2 nd connection target member 3 has a plurality of 2 nd electrodes 3a on a front surface (lower surface). The 1 st electrode 2a and the 2 nd electrode 3a are electrically connected by the solder portion 4A. Therefore, the 1 st connection object component 2 and the 2 nd connection object component 3 are electrically connected by the solder portion 4A. In the connection portion 4, solder is not present in a region (a portion of the cured product portion 4B) different from the solder portion 4A collected between the 1 st electrode 2a and the 2 nd electrode 3 a. In a region (a portion of the cured product portion 4B) different from the solder portion 4A, there is no solder separated from the solder portion 4A. If the amount is small, solder may be present in a region (a portion of the cured product 4B) different from the solder portion 4A collected between the 1 st electrode 2a and the 2 nd electrode 3 a. It should be noted that the solder preferably wetly spreads on the surfaces of the electrodes, and the solder does not necessarily have to be accumulated between the upper and lower electrodes.

As shown in fig. 1, in the connection structure 1, a plurality of solder particles are gathered between the 1 st electrode 2a and the 2 nd electrode 3a, and after the plurality of solder particles are melted, the melt of the solder particles wets and spreads on the surface of the electrodes and then solidifies to form the solder portion 4A. Therefore, the connection area between the solder portion 4A and the 1 st electrode 2a and the connection area between the solder portion 4A and the 2 nd electrode 3a become large. That is, by using the solder particles, the contact area between the solder portion 4A and the 1 st electrode 2a and the contact area between the solder portion 4A and the 2 nd electrode 3a become larger than in the case of using conductive particles whose outer surfaces are made of metal such as nickel, gold, or copper. Therefore, the connection structure 1 also has high conduction reliability and connection reliability. In general, the flux contained in the conductive material is gradually deactivated by heating.

In the connection structure 1 shown in fig. 1, all of the solder portions 4A are located in the region where the 1 st and 2

nd electrodes

2a and 3a face each other. A connection structure 1X of the modification shown in fig. 3 is different from the connection structure 1 shown in fig. 1 only in a connection portion 4X. The connection portion 4X has a solder portion 4XA and a cured product portion 4 XB. In the connection structure 1X, most of the solder portion 4XA is located in a region where the 1 st and 2

nd electrodes

2a and 3a face each other, and a part of the solder portion 4XA may bleed out in a lateral direction from the region where the 1 st and 2

nd electrodes

2a and 3a face each other. The solder portion 4XA which has oozed out in the lateral direction from the region where the 1 st and 2

nd electrodes

2a and 3a face each other is a part of the solder portion 4XA, and is not solder separated from the solder portion 4 XA. In the present embodiment, the amount of solder separated from the solder portion can be reduced, but the solder separated from the solder portion may be present in the cured product portion.

If the amount of solder particles used is reduced, the connection structure 1 can be easily obtained. If the amount of solder particles used is increased, the connection structure 1X can be easily obtained.

In the

connection structures

1 and 1X, when the 1 st electrode 2a and the 2 nd electrode 3a are opposed to each other in the lamination direction of the 1 st electrode 2a and the

connections

4 and 4X and the 2 nd electrode 3a, the solder portions 4A and 4XA in the

connections

4 and 4X are preferably arranged in an amount of 50% or more of 100% of the area of the 1 st electrode 2a and the 2 nd electrode 3a opposed to each other. The solder portions 4A and 4XA in the

connection portions

4 and 4X satisfy the above-described preferable mode, and thus conduction reliability can be further improved.

When the 1 st electrode and the 2 nd electrode are opposed to each other in a laminated direction of the 1 st electrode, the connecting portion and the 2 nd electrode, the solder portion in the connecting portion is preferably disposed in 50% or more of 100% of an area of the 1 st electrode and the 2 nd electrode opposed to each other. When the 1 st electrode and the 2 nd electrode are opposed to each other in a stacked direction of the 1 st electrode, the connection portion, and the 2 nd electrode, the solder portion in the connection portion is more preferably arranged in 60% or more of 100% of an area of the 1 st electrode and the 2 nd electrode opposed to each other. When the 1 st electrode and the 2 nd electrode are opposed to each other in a stacked direction of the 1 st electrode, the connection portion, and the 2 nd electrode, it is more preferable that the solder portion in the connection portion is disposed in 70% or more of 100% of an area of the 1 st electrode and the 2 nd electrode opposed to each other. When the facing portion of the 1 st electrode and the 2 nd electrode is viewed from the lamination direction of the 1 st electrode, the connection portion, and the 2 nd electrode, it is particularly preferable that the solder portion in the connection portion is disposed in 80% or more of 100% of the area of the facing portion of the 1 st electrode and the 2 nd electrode. When the 1 st electrode and the 2 nd electrode are opposed to each other when viewed from the lamination direction of the 1 st electrode, the connection portion, and the 2 nd electrode, it is most preferable that the solder portion in the connection portion is disposed at 90% or more of 100% of the area of the 1 st electrode and the 2 nd electrode opposed to each other. The solder portion in the connection portion satisfies the preferable aspect, and thereby conduction reliability can be further improved.

When the 1 st electrode and the 2 nd electrode are opposed to each other in a direction perpendicular to the lamination direction of the 1 st electrode, the connection portion, and the 2 nd electrode, it is preferable that 60% or more of the solder portion in the connection portion is arranged in the 1 st electrode and the 2 nd electrode opposed to each other. When the 1 st electrode and the 2 nd electrode are opposed to each other in a direction perpendicular to the lamination direction of the 1 st electrode, the connection portion, and the 2 nd electrode, it is more preferable that 70% or more of the solder portion in the connection portion is disposed in the 1 st electrode and the 2 nd electrode opposed to each other. When the 1 st electrode and the 2 nd electrode are opposed to each other in a direction perpendicular to the lamination direction of the 1 st electrode, the connection portion, and the 2 nd electrode, it is more preferable that 90% or more of the solder portion in the connection portion is disposed in the opposed portion of the 1 st electrode and the 2 nd electrode. When the 1 st electrode and the 2 nd electrode are opposed to each other in a direction perpendicular to the lamination direction of the 1 st electrode, the connection portion, and the 2 nd electrode, it is particularly preferable that 95% or more of the solder portion in the connection portion is arranged in the opposed portion of the 1 st electrode and the 2 nd electrode. When the 1 st electrode and the 2 nd electrode are opposed to each other in a direction perpendicular to the lamination direction of the 1 st electrode, the connection portion, and the 2 nd electrode, it is most preferable that 99% or more of the solder portion in the connection portion is disposed in the 1 st electrode and the 2 nd electrode opposed to each other. The solder portion in the connection portion satisfies the preferable aspect, and thereby conduction reliability can be further improved.

Next, fig. 2 illustrates an example of a method for manufacturing the connection structure 1 using the conductive material according to the embodiment of the present invention.

First, the 1 st connection target member 2 having the 1 st electrode 2a on the surface (upper surface) is prepared. Next, as shown in fig. 2a, the conductive material 11 including the thermosetting component 11B, the plurality of solder particles 11A, and the flux is disposed on the surface of the 1 st connection target member 2 (the 1 st step). The conductive material 11 used contains a thermosetting compound and a thermosetting agent as the thermosetting component 11B. In the present embodiment, the conductive material 11 is a conductive paste.

On the surface of the 1 st connection target member 2 on which the 1 st electrode 2a is provided, a conductive material 11 is disposed. After the conductive material 11 is disposed, the solder particles 11A are disposed at both on the 1 st electrode 2a (line) and on the region (space) where the 1 st electrode 2a is not formed. Note that the conductive material may be provided only on the surface of the 1 st electrode.

The method of disposing the conductive material 11 is not particularly limited, and examples thereof include application by a dispenser, screen printing, and discharge by an ink jet device.

Further, a 2 nd connection target member 3 having a 2 nd electrode 3a on the front surface (lower surface) is prepared. Next, as shown in fig. 2(b), the 2 nd connection object member 3 is disposed on the surface of the conductive material 11 on the opposite side of the 1 st connection object member 2 side of the conductive material 11 at the conductive material 11 on the surface of the 1 st connection object member 2 (2 nd step). On the surface of the conductive material 11, the 2 nd connection object member 3 is arranged from the 2 nd electrode 3a side. At this time, the 1 st electrode 2a and the 2 nd electrode 3a are opposed to each other.

Next, the conductive material 11 is heated to the melting point of the solder particles 11A or more (step 3). The conductive material 11 is preferably heated to a temperature equal to or higher than the curing temperature of the thermosetting component 11B (thermosetting compound). During this heating, the solder particles 11A that were present in the region where no electrode was formed are collected between the 1 st electrode 2a and the 2 nd electrode 3a (self-aggregation effect). In the case of using the conductive paste instead of the conductive film, the solder particles 11A are further effectively gathered between the 1 st electrode 2a and the 2 nd electrode 3 a. The solder particles 11A are melted and bonded to each other. The thermosetting component 11B is thermally cured. As a result, as shown in fig. 2(c), the connection portion 4 for connecting the 1 st connection object member 2 and the 2 nd connection object member 3 is formed of the conductive material 11. The connecting portion 4 is formed of the conductive material 11, the solder portion 4A is formed by bonding the plurality of solder particles 11A, and the cured product portion 4B is formed by thermosetting the thermosetting component 11B. If the solder particles 11A move sufficiently, the temperature may not be kept constant from the start of the movement of the solder particles 11A which are not positioned between the 1 st electrode 2a and the 2 nd electrode 3a until the completion of the movement of the solder particles 11A between the 1 st electrode 2a and the 2 nd electrode 3 a.

In the present embodiment, since the specific conductive material 11 is used, even if screen printing is repeatedly performed, occurrence of bleeding, blooming, or the like of the conductive material can be effectively suppressed. In the present embodiment, since the specific conductive material 11 is used, the shape of the conductive material after printing can be maintained. As a result, the solder particles 11A can be more efficiently arranged between the electrodes to be connected, and the conduction reliability and the insulation reliability can be more effectively improved. The conductive material according to the present invention may be printed by a method other than screen printing.

In the 2 nd step and the 3 rd step, it is preferable that the pressurization is not performed. In this case, the weight of the 2 nd connection object member 3 is applied to the conductive material 11. Therefore, the solder particles 11A are further effectively gathered between the 1 st electrode 2a and the 2 nd electrode 3a at the time of formation of the connection 4. In addition, if the pressurization is performed in at least one of the 2 nd step and the 3 rd step, the tendency of the solder particles 11A to gather between the 1 st electrode 2a and the 2 nd electrode 3a is increased.

In the present embodiment, since no pressurization is performed, even if the 1 st connection target member 2 and the 2 nd connection target member 3 are superposed with a slight misalignment between the 1 st electrode 2a and the 2 nd electrode 3a, the slight misalignment can be corrected to connect the 1 st electrode 2a and the 2 nd electrode 3a (self-alignment effect). This is because the solder that self-aggregates and melts between the 1 st electrode 2a and the 2 nd electrode 3a is energetically stable when the area where the solder and the other component of the conductive material between the 1 st electrode 2a and the 2 nd electrode 3a are in contact is minimized, and therefore, a force acts to achieve a connection structure having an aligned connection structure as a connection structure having a minimum area. In this case, it is preferable that the conductive material is not cured and the viscosity of the component other than the solder particles of the conductive material is sufficiently low at the temperature and for the time.

Thus, a connection structure 1 shown in fig. 1 was obtained. The 2 nd step and the 3 rd step may be continuously performed. After the step 2, the obtained laminate of the 1 st connection target member 2, the conductive material 11, and the 2 nd connection target member 3 may be moved to a heating section, and the step 3 may be performed. In order to perform the heating, the laminate may be disposed on a heating member, or may be disposed in a heated space.

The heating temperature in the step 3 is preferably 230 ℃ or higher, more preferably 250 ℃ or higher, preferably 450 ℃ or lower, more preferably 350 ℃ or lower, and further preferably 300 ℃ or lower.

Examples of the heating method in the above-mentioned 3 rd step include a method of heating the entire connection structure to a temperature equal to or higher than the melting point of the solder and equal to or higher than the curing temperature of the thermosetting component in a reflow furnace or an oven, and a method of heating only the connection portion of the connection structure locally.

Examples of the tool used in the local heating method include a hot plate, a heating gun for applying hot air, an iron, and an infrared heater.

When local heating is performed with a hot plate, the upper surface of the hot plate is preferably formed of a metal having high thermal conductivity at a portion below and near the connecting portion, and the upper surface of the hot plate is preferably formed of a material having low thermal conductivity, such as a fluororesin, at other portions where heating is not preferable.

The 1 st and 2 nd members to be connected are not particularly limited. Specific examples of the 1 st and 2 nd connection target members include electronic components such as a semiconductor chip, a semiconductor package, an LED chip, an LED package, a capacitor, and a diode, and electronic components such as a resin film, a printed circuit board, a flexible flat cable, a rigid flexible board, a glass epoxy substrate, and a circuit substrate such as a glass substrate. The 1 st and 2 nd connection object members are preferably electronic components.

At least one of the 1 st connection target member and the 2 nd connection target member is preferably a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid-flexible board. The resin film, the flexible printed board, the flexible flat cable, and the rigid-flexible board have high flexibility and relatively light weight. When a conductive film is used for connection of such members to be connected, solder particles tend to be less likely to gather on the electrodes. On the other hand, by using the conductive paste, solder particles can be efficiently collected on the electrodes even when a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible board is used, and thus the reliability of conduction between the electrodes can be sufficiently improved. When a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible board is used, the effect of improving the reliability of conduction between electrodes by not applying pressure can be more effectively obtained than when other connection target members such as a semiconductor chip are used.

Examples of the electrode provided on the connection target member include metal electrodes such as a gold electrode, a nickel electrode, a tin electrode, an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, an SUS electrode, and a tungsten electrode. 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. When the electrode is an aluminum electrode, the electrode may be formed of aluminum alone or may be formed by laminating an aluminum layer on the surface of a metal oxide layer. Examples of the material of the metal oxide layer include indium oxide doped with a metal element having a valence of 3, zinc oxide doped with a metal element having a valence of 3, and the like. Examples of the metal element having a valence of 3 include Sn, Al, and Ga.

In the connection structure according to the present invention, the 1 st electrode and the 2 nd electrode are preferably arranged in an Area array (Area array) or a Peripheral (Peripheral). In the case where the 1 st electrode and the 2 nd electrode are arranged in an area array or in the periphery, solder can be further efficiently condensed on the electrodes. The area array is a structure in which electrodes are arranged in a grid pattern on a surface of a connection target member on which the electrodes are arranged. The peripheral form is a structure in which an electrode is disposed on the outer periphery of the member to be connected. In the case of the structure in which the electrodes are arranged in a comb shape, the solder only needs to be condensed in a direction perpendicular to the comb, and in contrast to this, in the area array or the peripheral structure, the solder needs to be uniformly condensed over the entire surface of the surface on which the electrodes are arranged. Therefore, in the conventional method, the amount of solder tends to become uneven, and in contrast, in the method of the present invention, the solder can be uniformly aggregated over the entire surface.

The present invention will be specifically described below with reference to examples and comparative examples. However, the present invention is not limited to the following examples.

Thermosetting component (thermosetting compound):

thermosetting compound 1: phenol novolak type epoxy compound, "DEN 431" available from DOW corporation "

Thermosetting compound 2: bisphenol A type epoxy Compound, "DER 354" manufactured by DOW corporation "

Thermosetting compound 3: bisphenol F type epoxy Compound, YDF-8170C, manufactured by Nissian iron-goddess chemical Co., Ltd "

Thermosetting component (curing accelerator):

curing accelerator 1: boron trifluoride-monoethylamine complex "BF 3-MEA" manufactured by Tokyo chemical industries, Ltd

Solder particles:

solder particle 1: Sn96.5Ag3Cu0.5 solder particles (average particle diameter 5 μm, acid value 1.5mgKOH/g)

Solder particles 2: Sn96.5Ag3Cu0.5 solder particles (average particle diameter 2 μm, acid value 1.5mgKOH/g)

Solder particles 3: Sn96.5Ag3Cu0.5 solder particles (average particle diameter 0.1 μm, acid value 1.5mgKOH/g)

Solder particles 4: Sn96.5Ag3Cu0.5 solder particles (average particle diameter 2 μm, acid value 0.1mgKOH/g)

Solder particles 5: Sn96.5Ag3Cu0.5 solder particles (average particle diameter 2 μm, acid value 3.5mgKOH/g)

Solder particles 6: Sn96.5Ag3Cu0.5 solder particles (average particle diameter 10 μm, acid value 1.5mgKOH/g)

The average particle diameter and acid value of the solder particles are values measured by the methods described later.

Flux:

flux 1: "benzylamine adipate", melting point 171 ℃, solid at 23 ℃

The manufacturing method of the soldering flux 1 comprises the following steps:

into a glass bottle were added 45g of water and 75g of ethanol as reaction solvents, and 13.89g of adipic acid (Wako pure chemical industries, Ltd.) and the mixture was dissolved at room temperature until homogeneous. 10.715g of benzylamine (Wako pure chemical industries, Ltd.) was added thereto, and the mixture was stirred for about 5 minutes to obtain a mixed solution. The obtained mixed solution is put into a refrigerator with the temperature of 5-10 ℃ and is placed for one night. The precipitated crystals were separated by filtration, washed with water, and vacuum-dried to obtain flux 1.

(examples 1 to 6 and comparative examples 1 to 3)

(1) Production of conductive Material (Anisotropic conductive paste)

The components shown in tables 1 and 2 were mixed in the amounts shown in tables 1 and 2 to obtain conductive materials (anisotropic conductive pastes).

(2) Production of connection Structure

As the 1 st connection target member, a glass epoxy substrate (FR-4 substrate, thickness 0.6mm) having a copper electrode pattern (L/S: 50 μm/50 μm, length of electrode: 3mm, thickness of electrode: 12 μm) on the upper surface was prepared.

As the 2 nd connection target member, a flexible printed board (made of polyimide and having a thickness of 0.1mm) having a copper electrode pattern (L/S: 50 μm/50 μm, length of electrode: 3mm, thickness of electrode: 12 μm) on the lower surface was prepared.

On the upper surface of the glass epoxy substrate, printing was performed by screen printing so that the thickness of the conductive material (anisotropic conductive paste) just produced was 100 μm, thereby forming a conductive material (anisotropic conductive paste) layer. Next, a flexible printed board is laminated on the upper surface of the conductive material (anisotropic conductive paste) layer so that the electrodes face each other. The weight of the flexible printed substrate is applied to the conductive material (anisotropic conductive paste) layer. In this state, heating is performed so that the temperature of the conductive material (anisotropic conductive paste) layer reaches the melting point of the solder particles after 5 seconds from the start of temperature rise. After 15 seconds from the start of the temperature increase, the conductive material (anisotropic conductive paste) layer was heated to 200 ℃ to cure the conductive material (anisotropic conductive paste) layer, thereby obtaining a connection structure. During heating, no pressurization was performed.

(evaluation)

(1) Average particle diameter of solder particles

The average particle diameter of the solder particles was measured by a laser diffraction type particle size distribution measuring apparatus ("LA-920" manufactured by horiba Ltd.).

(2) Acid value of solder particles

1g of solder particles was added to 10g of water, and dispersed by ultrasonic waves for 1 minute. Then, titration was carried out with 0.1mol/L ethanol solution of potassium hydroxide using phenolphthalein as an indicator.

(3) Viscosity (. eta.25) at 25 ℃ of freshly prepared conductive material

The viscosity (. eta.25) of the obtained conductive material (anisotropic conductive paste) was measured at 25 ℃ and 5rpm immediately after production with an E-type viscometer ("TVE 22L", manufactured by Toyobo industries Co., Ltd.).

[ criterion for determining viscosity (. eta.25) ]

O ^ O: 120Pa · s or more and 180Pa · s or less

O: 100 pas or more and less than 120 pas or more and 200 pas or less than 180 pas

X: less than 100 pas, or, more than 200 pas

(4) Thawing frozen conductive material, and allowing the conductive material to have viscosity (eta A) at 25 deg.C just before 25 deg.C

The obtained conductive material (anisotropic conductive paste) was stored at-40 ℃ for 7 days under refrigeration. Next, the conductive material subjected to the freezing storage was stored at 25 ℃ and thawed. The frozen and stored conductive material was thawed, and the viscosity (. eta.A) at 25 ℃ and 5rpm of the conductive material immediately after reaching 25 ℃ was measured using an E-type viscometer ("TVE 22L" manufactured by Toyobo industries, Ltd.).

[ criterion for determining viscosity (. eta.A) ]

O ^ O: 120Pa · s or more and 180Pa · s or less

X: less than 100 pas, or, more than 200 pas

(5) Thawing the frozen conductive material, storing at 25 deg.C and 50% RH for 24 hr to obtain a conductive material with viscosity (eta B) at 25 deg.C

The obtained conductive material (anisotropic conductive paste) was stored at-40 ℃ for 7 days under refrigeration. Next, the conductive material subjected to the freezing storage was stored at 25 ℃ and thawed. Then, the mixture was stored at 25 ℃ and 50% RH for 24 hours. The viscosity (. eta.B) of the conductive material after 24 hours storage at 25 ℃ and 5rpm was measured using an E-type viscometer ("TVE 22L", manufactured by Toyobo industries Co., Ltd.).

Then, from the obtained values of the viscosity (η a) and the viscosity (η B), a ratio (viscosity (η B)/viscosity (η a)) was calculated.

[ criterion for determining viscosity (. eta.B) ]

O ^ O: viscosity (. eta.B) of 120 to 180 Pa.s

O: the viscosity (. eta.B) is 100 pas or more and less than 120 pas or more and more than 180 pas and 300 pas or less

X: the viscosity (. eta.B) is less than 100 pas or more than 300 pas

[ criterion for determining the ratio (viscosity (. eta.B)/viscosity (. eta.A) ]

O ^ O: a ratio (viscosity (. eta.B)/viscosity (. eta.A)) of 1.0 to 1.5

O: a ratio (viscosity (. eta.B)/viscosity (. eta.A)) of 0.8 or more and less than 1.0, or more than 1.5 and 2.0 or less

X: the ratio (viscosity (. eta.B)/viscosity (. eta.A)) is less than 0.8, or, exceeds 2.0

(6) Arrangement accuracy of solder on electrode

With respect to the obtained connection structure, the ratio X of the area of the solder portion in the connection portion was evaluated in 100% of the area of the opposing portion of the 1 st electrode and the 2 nd electrode when the opposing portion of the 1 st electrode and the 2 nd electrode was viewed from the lamination direction of the 1 st electrode and the connection portion and the 2 nd electrode. The placement accuracy of the solder on the electrodes was determined by the following criteria.

[ criterion for determining the accuracy of the placement of solder on electrodes ]

O ^ O: the ratio X is more than 70%

O: the proportion X is more than 50 percent and less than 70 percent

X: the proportion X is less than 50 percent

(7) Continuous printability

For the obtained conductive material, screen printing was performed on a glass Slide (Slide glass) using a metal mask having a size of 130mm × 175mm for each opening and a thickness of 40 μm. The printed pattern was observed with the naked eye and a solid microscope on the printed surface immediately after the printing was completed, and the dimensions were measured to confirm whether bleeding or white streaks occurred. The screen printing was continuously performed, the number of times printing could be performed without bleeding or blush was checked, and the continuous printability was determined by the following criteria.

[ criterion for judgment of bleeding or whitening ]

[ bleed out ]: immediately after printing, a portion thicker than 20% of the plate making size may be present

[ whitening ]: immediately after printing, a portion missing by 20% or more of the plate making size may be present

[ criterion for determining continuous printability ]

O ^ O: the number of printing times is 25 or more without bleeding or blooming

O: the number of printing operations without bleeding or blush is 11 to 24

X: the number of printing times is 10 or less without bleeding or white streaks

The details and results are shown in tables 1 and 2 below. In tables 1 and 2, the viscosity (. eta.25) is the viscosity at 25 ℃ of the as-fabricated conductive material. In tables 1 and 2, the viscosity (. eta.A) is the viscosity at 25 ℃ of the frozen and stored conductive material immediately after the conductive material is thawed to 25 ℃. In tables 1 and 2, the viscosity (. eta.B) is the viscosity at 25 ℃ of the conductive material after the conductive material stored in a frozen state is thawed and stored at 25 ℃ and 50% RH for 24 hours.

In addition, whether or not voids were generated in the connecting portions was confirmed by observing the connecting portions with a scanning electron microscope, and as a result, voids were not generated in the connecting structures obtained in examples 1 to 6.

The same tendency is observed in the case of using a flexible printed circuit board, a resin film, a flexible flat cable, and a rigid flexible board.

Description of the symbols

1. 1X … connection structure

2 … part to be connected 1 st

2a … st electrode

3 … part 2 to be connected

3a … nd electrode 2

4. 4X … connection part

4A, 4XA … solder part

Cured product part of 4B, 4XB …

11 … conductive material

11a … solder particles

11B … Heat curing Components

Claims

1. A conductive material comprising a thermosetting component, a plurality of solder particles, and a flux, wherein,

the solder particles have an average particle size of less than 10 μm,

the acid value of the solder particles is 0.3mgKOH/g or more and 3mgKOH/g or less.

2. The conductive material of claim 1,

the conductive material stored in a frozen state is thawed, and the viscosity of the conductive material at 25 ℃ is 100Pa & s or more and 200Pa & s or less.

3. The conductive material according to claim 1 or 2,

the conductive material after frozen storage is thawed, and the viscosity of the conductive material at 25 ℃ after 24 hours of storage at 25 ℃ and 50% RH is 100 Pa.s or more and 300 Pa.s or less.

4. The conductive material according to any one of claims 1 to 3,

the thermosetting component contains an epoxy compound.

5. The conductive material according to any one of claims 1 to 4,

the solder particles have an average particle size of less than 1 μm.

6. The conductive material according to any one of claims 1 to 5, which is a conductive paste.

7. A connection structure body is provided with:

a1 st connection target member having a1 st electrode on the surface,

A 2 nd connection object member having a 2 nd electrode on the surface thereof, and

a connecting portion for connecting the 1 st connection target member and the 2 nd connection target member,

the material of the connecting part is the conductive material of any one of claims 1 to 6,

the 1 st electrode and the 2 nd electrode are electrically connected by a solder portion in the connection portion.

8. A method for manufacturing a connection structure, comprising:

disposing the conductive material according to any one of claims 1 to 6 on a surface of a1 st connection target member having a1 st electrode on the surface thereof;

disposing a 2 nd connection target member having a 2 nd electrode on a surface of the conductive material opposite to the 1 st connection target member side so that the 1 st electrode and the 2 nd electrode face each other; and

and a step of forming a connection portion for connecting the 1 st connection target component and the 2 nd connection target component by using the conductive material by heating the conductive material to a melting point of the solder particles or higher, and electrically connecting the 1 st electrode and the 2 nd electrode by a solder portion in the connection portion.