JP7421317B2 - Conductive film and connected structure - Google Patents

Description

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

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

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

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

Patent Document 1 listed below discloses a conductive material that includes a plurality of conductive particles having solder and a thermosetting component on the outer surface of a conductive part. In the above conductive material, the minimum value of the viscosity of the conductive material at 25° C. or higher and below the melting point of the solder in the conductive particles is 25 Pa·s or more and 255 Pa·s or less. The average particle diameter of the conductive particles is 3 μm or more and 15 μm or less. In the conductive material, where A is the average particle diameter (μm) of the conductive particles, and B is the viscosity (Pa・s) of the conductive material at the melting point of the solder in the conductive particles, the B is , (-5A+100) or more and (-15A+300) or less.

WO2017/033931A1

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

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

With conventional conductive materials, when screen printing is performed repeatedly, the viscosity of the conductive material during printing is low, the amount of screen penetration increases, and bleeding of the conductive material occurs, or the viscosity of the conductive material during printing becomes high. Therefore, the conductive material may clog the mesh, causing the conductive material to become blurred. With conventional conductive materials, when screen printing is performed continuously, bleeding of the conductive material or blurring of the conductive material may occur, making it difficult to perform screen printing continuously.

Additionally, with conventional conductive materials, it may be difficult to maintain the shape of the conductive material after printing. If the shape of the conductive material after printing cannot be maintained, the conductive material may move away from its original location (for example, near an electrode). With conventional conductive materials, the shape of the conductive material after printing cannot be maintained, and solder particles may not be efficiently placed between the upper and lower electrodes to be connected. As a result, solder particles contained in the conductive material are placed in areas where no electrodes are formed, reducing the amount of solder particles placed between the upper and lower electrodes to be connected, and reducing the amount of solder particles placed between the upper and lower electrodes to be connected. The reliability of conduction between adjacent electrodes may be lowered, or the reliability of insulation between adjacent horizontal electrodes may be lowered.

An object of the present invention is to provide a conductive material that can be continuously screen printed and that can also efficiently place solder on electrodes. Another object of the present invention is to provide a connected structure using the above conductive material and a method for manufacturing the connected structure.

According to a broad aspect of the invention, there is provided an electrically conductive material comprising a thermosetting component and a plurality of solder particles, wherein the electrically conductive material does not contain a solvent or contains a solvent in 100% by weight of the electrically conductive material. 1% by weight or less, the viscosity of the conductive material at 25° C. and a shear rate of 600 sec ⁻¹ is 1 Pa·s or more and 20 Pa·s or less, and the conductive material at 25° C. and a shear rate of 0.06 sec ⁻¹ Provided is a conductive material having a viscosity of 1000 Pa·s or more and 3500 Pa·s or less, and a tan δ of 2 or more and 10 or less at 25° C. and a frequency of 1 Hz.

In a particular aspect of the electrically conductive material according to the present invention, the electrically conductive material contains a fatty acid amine salt or a fatty acid amide.

In a particular aspect of the conductive material according to the present invention, the solder particles have an average particle diameter of 1 μm or more and 15 μm or less.

In a particular aspect of the conductive material according to the present invention, the content of the solder particles is 40% by weight or more and 75% by weight or less in 100% by weight of the conductive material.

In a particular aspect of the conductive material according to the present invention, the thermosetting component includes a thermosetting compound, and the thermosetting compound has a viscosity of 1 Pa·s or more and 100 Pa·s or less at 25°C. .

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

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

According to a broad aspect of the present invention, the above-described conductive material is disposed on the surface of a first connection target member having a first electrode on its surface; A second connection target member having a second electrode on its surface is arranged on a surface opposite to the first connection target member side so that the first electrode and the second electrode face each other. forming a connection portion connecting the first connection target member and the second connection target member with the conductive material by heating the conductive material to a temperature equal to or higher than the melting point of the solder particles; There is provided a method for manufacturing a connected structure, comprising the steps of: electrically connecting the first electrode and the second electrode with a solder portion in the connecting portion.

The electrically conductive material according to the present invention includes a thermosetting component and a plurality of solder particles. In the electrically conductive material according to the present invention, the electrically conductive material does not contain a solvent, or contains 1% by weight or less of a solvent in 100% by weight of the electrically conductive material. In the present invention, the viscosity of the conductive material at 25° C. and a shear rate of 600 sec ⁻¹ is 1 Pa·s or more and 20 Pa·s or less. In the present invention, the viscosity of the conductive material at 25° C. and a shear rate of 0.06 sec ⁻¹ is 1000 Pa·s or more and 3500 Pa·s or less. In the present invention, the tan δ of the conductive material at 25° C. and a frequency of 1 Hz is 2 or more and 10 or less. Since the conductive material according to the present invention has the above configuration, screen printing can be performed continuously, and furthermore, solder can be efficiently placed on the electrodes.

FIG. 1 is a cross-sectional view schematically showing a connected structure obtained using a conductive material according to an embodiment of the present invention. FIGS. 2(a) to 2(c) are cross-sectional views for explaining each step of an example of a method for manufacturing a connected structure using a conductive material according to an embodiment of the present invention. FIG. 3 is a sectional view showing a modification of the connected structure.

The details of the present invention will be explained below.

(conductive material)
The electrically conductive material according to the present invention includes a thermosetting component and a plurality of solder particles. In the electrically conductive material according to the present invention, the electrically conductive material does not contain a solvent, or contains 1% by weight or less of a solvent in 100% by weight of the electrically conductive material. In the present invention, the viscosity of the conductive material at 25° C. and a shear rate of 600 sec ⁻¹ is 1 Pa·s or more and 20 Pa·s or less. In the present invention, the viscosity of the conductive material at 25° C. and a shear rate of 0.06 sec ⁻¹ is 1000 Pa·s or more and 3500 Pa·s or less. In the present invention, the tan δ of the conductive material is 2 or more and 10 or less when measured at 25° C. and a frequency of 1 Hz.

Since the conductive material according to the present invention has the above configuration, screen printing can be performed continuously, and furthermore, solder can be efficiently placed on the electrodes.

With conventional conductive materials, when screen printing is performed repeatedly, the viscosity of the conductive material during printing is low, the amount of screen penetration increases, and bleeding of the conductive material occurs, and the viscosity of the conductive material during printing becomes high. When the mesh is clogged with the conductive material, the conductive material may become blurred.

Additionally, with conventional conductive materials, it may be difficult to maintain the shape of the conductive material after printing. If the shape of the conductive material after printing cannot be maintained, the conductive material may move away from its original location (for example, near an electrode). With conventional conductive materials, the shape of the conductive material after printing cannot be maintained, and solder particles may not be efficiently placed between the upper and lower electrodes to be connected.

The present inventors focused on the viscoelastic properties of conductive materials and discovered that by using a specific conductive material, the viscoelastic properties of the conductive materials can be controlled. In the present invention, by controlling the viscoelastic properties of the conductive material, it is possible to effectively suppress the occurrence of bleeding of the conductive material or blurring of the conductive material during screen printing, and it is possible to perform screen printing continuously. Can be done. In addition, in the present invention, by controlling the viscoelastic properties of the conductive material, the shape of the conductive material after printing can be maintained, and the amount of solder particles placed between the upper and lower electrodes to be connected can be sufficiently reduced. can be secured. As a result, the reliability of conduction between the upper and lower electrodes to be connected can be effectively improved.

Furthermore, in the present invention, when conductive connection is made between electrodes, a plurality of solder particles easily gather between upper and lower opposing electrodes, and a plurality of solder particles can be arranged on an electrode (line). In addition, it is difficult for some of the plurality of solder particles to be placed between horizontal electrodes that should not be connected, and it is possible to considerably reduce the amount of solder particles that are placed between horizontal electrodes that should not be connected. can. As a result, the present invention can effectively increase the continuity reliability between the upper and lower electrodes that should be connected, and can effectively increase the insulation reliability between adjacent lateral electrodes that should not be connected. Can be done.

In the present invention, the use of a specific conductive material greatly contributes to obtaining the above effects.

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

When the viscosity (ηA) of the conductive material is measured at 25° C. and a shear rate of 600 sec ⁻¹ , the viscosity (ηA) is 1 Pa·s or more and 20 Pa·s or less. From the viewpoint of performing screen printing more continuously and more efficiently disposing the solder on the electrode, the viscosity (ηA) is preferably 5 Pa·s or more, preferably 10 Pa·s. s or less.

When the viscosity (ηB) of the conductive material is measured at 25° C. and a shear rate of 0.06 sec ⁻¹ , the viscosity (ηB) is 1000 Pa·s or more and 3500 Pa·s or less. From the viewpoint of performing screen printing more continuously and more efficiently disposing the solder on the electrode, the viscosity (ηB) is preferably 2000 Pa·s or more, preferably 3000 Pa·s. s or less.

The viscosity (ηA and ηB) can be measured using a rheometer (manufactured by Thermo Scientific, type: HAAKE) or the like. Specifically, it can be measured as follows.

At a constant temperature of 25° C., a shear rate of 100 sec ⁻¹ is applied as a pre-shear for 60 seconds to the conductive material, and then left to stand for 5 minutes. Next, the shear rate is changed from 0 sec ^-1 to 1000 sec ^-1 in 120 seconds, and then the shear rate is changed from 1000 sec ^-1 to 0 sec ^-1 in 120 seconds, and measurement is performed. In this measurement, when the shear rate is changed from 1000 sec ^-1 to 0 sec ^-1 in 120 seconds, the viscosity at a shear rate of 600 sec ^-1 is defined as ηA, and the viscosity at a shear rate of 0.06 sec ^-1 is defined as ηB.

When the tan δ of the conductive material is measured at 25° C. and a frequency of 1 Hz, the tan δ is 2 or more and 10 or less. From the viewpoint of continuously performing screen printing more effectively and from the viewpoint of arranging solder on the electrodes more efficiently, the tan δ is preferably 4 or more, and preferably 7 or less.

The tan δ can be measured using a rheometer (manufactured by Thermo Scientific, type: HAAKE) or the like. Specifically, it can be measured as follows.

At a constant temperature of 25° C., the strain applied to the conductive material is varied by sweeping from 0 to 100% at a frequency of 1 Hz, and the storage modulus (G') and loss modulus (G'') are measured. Tan δ (G''/G') is calculated from the obtained storage modulus (G') and loss modulus (G'').

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

Each component contained in the above conductive material will be explained below. In addition, in this specification, "(meth)acrylic" means one or both of "acrylic" and "methacrylic."

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

The solder is preferably a metal having a melting point of 450° C. or lower (low melting point metal). The solder particles are preferably metal particles having a melting point of 450° C. or lower (low-melting point metal particles). The low melting point metal particles are particles containing a low melting point metal. The low melting point metal refers to a metal having a melting point of 450° C. or lower. The melting point of the low melting point metal is preferably 300°C or lower, more preferably 230°C or lower. The solder is preferably a low melting point solder having a melting point of less than 230°C.

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

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

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

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

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

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

In the conductive material according to the present invention, the average particle diameter of the solder particles is preferably 1 μm or more, more preferably 2 μm or more, preferably 15 μm or less, more preferably 10 μm or less, still more preferably less than 10 μm, particularly preferably It is 7 μm or less. When the average particle diameter of the solder particles is not less than the above lower limit and not more than the above upper limit, the solder can be disposed on the electrode even more efficiently. It is particularly preferable that the average particle diameter of the solder particles is 2 μm or more and 10 μm or less.

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

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

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

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

The shape of the solder particles is not particularly limited. The shape of the solder particles may be spherical, non-spherical, flat, etc. The shape of the solder particles is preferably spherical. The solder particles are preferably spherical particles.

The content of the solder particles in 100% by weight of the conductive material is preferably 40% by weight or more, more preferably 45% by weight or more, still more preferably 50% by weight or more, particularly preferably 55% by weight or more, and most preferably The content is 60% by weight or more, preferably 75% by weight or less, more preferably 70% by weight or less, even more preferably 65% by weight or less. When the content of the solder particles is above the above lower limit and below the above upper limit, the solder can be placed on the electrodes even more efficiently, it is easy to place a large amount of solder between the electrodes, and conduction is ensured. Reliability can be improved even more effectively. From the viewpoint of further effectively increasing conduction reliability, it is preferable that the content of the solder particles be large.

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

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

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

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

In the conductive material according to the present invention, the viscosity of the thermosetting compound at 25° C. is preferably 1 Pa·s or more, more preferably 3 Pa·s or more, and preferably 100 Pa·s or less, more preferably 60 Pa·s. s or less. When the viscosity of the thermosetting compound is not less than the lower limit and not more than the upper limit, screen printing can be performed even better and continuously, and the solder can be placed on the electrode more efficiently. .

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

From the viewpoint of further effectively increasing the insulation reliability and the viewpoint of further effectively increasing the conduction reliability, the thermosetting component preferably contains an epoxy compound, and the thermosetting compound preferably contains an epoxy compound. It is preferable to include.

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

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

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

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

To more efficiently arrange solder on the electrodes, to more effectively increase the reliability of conduction between the upper and lower electrodes to be connected, and to more effectively suppress discoloration of thermosetting compounds. From this point of view, the thermosetting compound preferably has high heat resistance, and is more preferably a novolak-type epoxy compound. Novolak-type epoxy compounds have relatively high heat resistance.

The content of the thermosetting compound in 100% by weight of the conductive material is preferably 5% by weight or more, more preferably 8% by weight or more, even more preferably 10% by weight or more, and preferably 99% by weight or less, The content is more preferably 90% by weight or less, further preferably 80% by weight or less, particularly preferably 70% by weight or less. When the content of the thermosetting compound is at least the above lower limit and below the above upper limit, the solder can be placed on the electrodes even more efficiently, and the insulation reliability between the electrodes can be further effectively increased. , it is possible to further effectively improve the reliability of conduction between the electrodes. From the viewpoint of increasing impact resistance even more effectively, it is preferable that the content of the thermosetting compound is as large as possible.

The content of the epoxy compound in 100% by weight of the conductive material is preferably 5% by weight or more, more preferably 8% by weight or more, even more preferably 10% by weight or more, and preferably 99% by weight or less, more preferably is 90% by weight or less, more preferably 80% by weight or less, particularly preferably 70% by weight or less. When the content of the epoxy compound is not less than the lower limit and not more than the upper limit, the solder can be placed on the electrode more efficiently, and the insulation reliability between the electrodes can be further effectively increased. The reliability of conduction between the two can be further effectively improved. From the viewpoint of further improving impact resistance, it is preferable that the content of the epoxy compound is as large as possible.

(Thermosetting component: thermosetting agent)
The conductive material may contain a thermosetting agent. The conductive material may contain a thermosetting agent together with the thermosetting compound. The thermosetting agent thermosets the thermosetting compound. The above thermosetting agent is not particularly limited. Examples of the thermosetting agent include imidazole curing agents, phenol curing agents, thiol curing agents, amine curing agents, acid anhydride curing agents, thermal cation curing agents, and thermal radical generators. The above thermosetting agents may be used alone or in combination of two or more.

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

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

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

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

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

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

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

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

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

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

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

The content of the curing accelerator is appropriately selected so that the thermosetting compound is well cured. The content of the curing accelerator relative to 100 parts by weight of the thermosetting compound is preferably 0.5 parts by weight or more, more preferably 0.8 parts by weight or more, and preferably 10 parts by weight or less, more preferably 8 parts by weight. Parts by weight or less. When the content of the curing accelerator is at least the above lower limit and at most the above upper limit, the thermosetting compound can be cured well. In addition, when the content of the curing accelerator is at least the above lower limit and below the above upper limit, the solder can be placed on the electrodes even more efficiently, and the continuity reliability between the upper and lower electrodes to be connected is improved. can be increased even more effectively.

(solvent)
The conductive material according to the present invention does not contain a solvent, or contains 1% by weight or less of a solvent in 100% by weight of the conductive material. The conductive material preferably contains 1% by weight or less of a solvent in 100% by weight of the conductive material, and more preferably does not contain a solvent. When the above-mentioned solvent satisfies the above-mentioned preferred embodiments, screen printing can be carried out in a better and continuous manner, and the solder can be disposed on the electrodes more efficiently. Only one type of the above solvent may be used, or two or more types may be used in combination.

Examples of the solvent include water and organic solvents. Organic solvents are preferred because they can be easily removed. Examples of the organic solvents include alcohol compounds such as ethanol, ketone compounds such as acetone, methyl ethyl ketone, and cyclohexanone, aromatic hydrocarbon compounds such as toluene, xylene, and tetramethylbenzene, cellosolve, methyl cellosolve, butyl cellosolve, carbitol, and methyl carbitol. , glycol ether compounds such as butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, tripropylene glycol monomethyl ether, ethyl acetate, butyl acetate, butyl lactate, cellosolve acetate, butyl cellosolve acetate, carbitol Ester compounds such as acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, propylene carbonate, aliphatic hydrocarbon compounds such as octane and decane, petroleum solvents such as petroleum ether and naphtha, etc. Can be mentioned.

Preferably, the solvent evaporates when heated at 260° C. for 5 minutes. Examples of the solvent that satisfies the above preferred embodiments include benzyl glycol, diethylene glycol monohexyl ether, and diethylene glycol mono-2-ethylhexyl ether. The solvent is preferably benzyl glycol or diethylene glycol monohexyl ether.

(Fatty acid amine salt or fatty acid amide)
The conductive material preferably contains a fatty acid amine salt or a fatty acid amide. The conductive material may contain only a fatty acid amine salt, only a fatty acid amide, or a fatty acid amine salt and a fatty acid amide. By using fatty acid amine salts or fatty acid amides, the viscoelastic properties of the conductive material can be further improved, screen printing can be performed better and continuously, and the solder can be applied more efficiently to the electrodes. It can be placed as follows. The above-mentioned fatty acid amine salt and the above-mentioned fatty acid amide may be used in a conductive material as a flux described below. The fatty acid amine salt and the fatty acid amide may be used in the conductive material as an additive different from the flux described below. The above fatty acid amine salts may be used alone or in combination of two or more. The above fatty acid amides may be used alone or in combination of two or more.

Examples of the fatty acid amine salts include benzylamine glutarate, benzylamine adipate, hexylamine glutarate, and the like. From the viewpoint of further improving the viscoelastic properties of the conductive material, the viewpoint of performing continuous screen printing even better, and the viewpoint of disposing the solder on the electrode more efficiently, the fatty acid amine salt is Preferably, it is glutaric acid benzylamine salt or adipic acid benzylamine salt.

Examples of the fatty acid amides include glutaric acid benzylamide, adipic acid benzylamide, glutaric acid hexylamide, and the like. From the viewpoint of further improving the viscoelastic properties of the conductive material, improving continuous screen printing, and disposing the solder on the electrode more efficiently, the fatty acid amide is glutaric. Preference is given to acid benzylamide or adipic acid benzylamide.

The content of the fatty acid amine salt in 100% by weight of the conductive material is preferably 1% by weight or more, more preferably 3% by weight or more, and preferably 10% by weight or less, more preferably 7% by weight or less. . The conductive material does not need to contain the fatty acid amine salt. When the content of the fatty acid amine salt is at least the above lower limit and below the above upper limit, the viscoelastic properties of the conductive material can be further improved, and screen printing can be performed even better and continuously. , it is possible to more efficiently arrange the solder on the electrode.

The content of the fatty acid amide in 100% by weight of the conductive material is preferably 0.2% by weight or more, more preferably 0.5% by weight or more, and preferably 3% by weight or less, more preferably 2% by weight. It is as follows. The conductive material does not need to contain the fatty acid amide. When the content of the fatty acid amide is not less than the lower limit and not more than the upper limit, the viscoelastic properties of the conductive material can be further improved, and screen printing can be performed continuously even better. Solder can be placed on the electrodes even more efficiently.

(flux)
The conductive material may contain flux. By using flux, the cohesiveness of solder during conductive connection can be further effectively increased. The above flux is not particularly limited. As the above-mentioned flux, a flux commonly used for soldering and the like can be used. The above-mentioned flux may be the above-mentioned fatty acid amine salt or fatty acid amide. The above-mentioned flux may contain compounds other than the above-mentioned fatty acid amine salt or fatty acid amide.

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

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

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

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

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

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

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

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

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

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

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

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

From the viewpoint of arranging the solder more efficiently on the electrode, from the viewpoint of further increasing the insulation reliability, and from the viewpoint of further effectively increasing the conduction reliability, the above-mentioned flux is composed of an acid compound and a basic compound. It is preferable that it is a salt with. The acid compound preferably has the effect of cleaning the surface of the metal, and the base compound preferably has the effect of neutralizing the acid compound. The flux is preferably a neutralization reaction product (salt) of the acid compound and the base compound.

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

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

The content of the flux in 100% by weight of the conductive material is preferably 1% by weight or more, preferably 10% by weight or less, and more preferably 7% by weight or less. When the content of the flux is more than the above lower limit and less than the above upper limit, it becomes even more difficult to form an oxide film on the surfaces of the solder and electrodes, and furthermore, it becomes even more difficult to form an oxide film on the surfaces of the solder and electrodes. Can be removed effectively.

(filler)
The above-mentioned conductive material may contain a filler. The filler may be an organic filler or an inorganic filler. By adding the filler, the solder can be more uniformly aggregated over all the electrodes on the substrate.

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

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

(other ingredients)
The above-mentioned conductive material may include fillers, extenders, softeners, plasticizers, thickeners, thixotropic agents, leveling agents, polymerization catalysts, curing catalysts, colorants, antioxidants, and heat stabilizers, as necessary. , a light stabilizer, an ultraviolet absorber, a lubricant, an antistatic agent, and a flame retardant.

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

A method for manufacturing a connected structure according to the present invention includes a step of using the above-mentioned conductive material and arranging the above-described conductive material on the surface of a first connection target member having a first electrode on the surface. The method for manufacturing a connected structure according to the present invention includes a method for manufacturing a connected structure, in which a second connection target member having a second electrode on the surface is placed on a surface of the conductive material opposite to the first connection target member side. The method includes a step of arranging the first electrode and the second electrode so as to face each other. The method for manufacturing a connected structure according to the present invention provides a connection between the first connection target member and the second connection target member by heating the conductive material above the melting point of the solder particles. forming a portion of the electrically conductive material, and electrically connecting the first electrode and the second electrode with a solder portion in the connecting portion.

In the bonded structure and the method for manufacturing the bonded structure according to the present invention, since a specific conductive material is used, solder particles tend to collect between the first electrode and the second electrode. line). Furthermore, some of the solder particles are less likely to be placed in areas (spaces) where no electrodes are formed, and the amount of solder particles placed in areas where no electrodes are formed can be considerably reduced. Therefore, the reliability of conduction between the first electrode and the second electrode can be improved. Moreover, electrical connection between horizontally adjacent electrodes that should not be connected can be prevented, and insulation reliability can be improved.

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

In the method for manufacturing a connected structure according to the present invention, in the step of arranging the second connection target member and the step of forming the connection part, no pressure is applied to the conductive material, and the second connection target member is not pressurized. Preferably, the weight of the target member is added. In the method for manufacturing a connected structure according to the present invention, in the step of arranging the second member to be connected and the step of forming the connecting portion, the conductive material is subjected to the force of the weight of the second member to be connected. It is preferable not to apply pressure exceeding . In these cases, the uniformity of the amount of solder can be further improved in the plurality of solder parts. Furthermore, the thickness of the solder part can be increased even more effectively, making it easier for multiple solder particles to gather between the electrodes, making it possible to more efficiently arrange multiple solder particles on the electrodes (lines). can. In addition, it is difficult for some of the plurality of solder particles to be placed in areas (spaces) where electrodes are not formed, and it is possible to further reduce the amount of solder in solder particles placed in areas where electrodes are not formed. can. Therefore, the reliability of conduction between the electrodes can be further improved. Moreover, electrical connections between horizontally adjacent electrodes that should not be connected can be further prevented, and insulation reliability can be further improved.

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

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

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

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

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

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

As shown in FIG. 1, in the connection structure 1, a plurality of solder particles gather between a first electrode 2a and a second electrode 3a, and after the plurality of solder particles are melted, a melted solder particle is formed. The solder portion 4A is formed by wetting and spreading the surface of the electrode and solidifying the solder portion 4A. Therefore, the connection area between the solder portion 4A and the first electrode 2a and between the solder portion 4A and the second electrode 3a becomes large. In other words, by using solder particles, the solder portion 4A, the first electrode 2a, and the solder can be bonded more easily than when using conductive particles in which the outer surface of the conductive portion is made of metal such as nickel, gold, or copper. The contact area between the portion 4A and the second electrode 3a becomes larger. Therefore, the conduction reliability and connection reliability in the connected structure 1 are increased. Note that the flux contained in the conductive material is generally gradually deactivated by heating.

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

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

The thickness of the solder portion between the first electrode and the second electrode is preferably 10 μm or more, more preferably 20 μm or more, and preferably 100 μm or less, more preferably 80 μm or less. In the first electrode and the second electrode, the solder wetted area on the surface of the electrode (the area in contact with the solder out of 100% of the exposed area of the electrode) is preferably 50% or more, more preferably 60% or more. % or more, more preferably 70% or more, and preferably 100% or less. When the solder part in the connection part satisfies the above-mentioned preferable aspects, conduction reliability and insulation reliability can be further effectively improved.

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

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

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

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

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

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

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

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

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

In this embodiment, since a specific conductive material 11 is used, it is possible to effectively suppress the occurrence of bleeding of the conductive material, blurring of the conductive material, etc. even if screen printing is repeatedly performed. Further, in this embodiment, since a 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 continuity reliability and insulation reliability can be improved even more effectively.

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

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

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

The heating temperature in the third step is preferably 220°C or higher, more preferably 240°C or higher, and preferably 300°C or lower, more preferably 260°C or lower. When the heating temperature in the third step is not less than the lower limit and not more than the upper limit, the solder can be placed on the electrodes even more efficiently, and the continuity reliability between the upper and lower electrodes to be connected is improved. can be increased even more effectively.

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

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

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

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

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

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

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

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

Thermosetting component (thermosetting compound):
Thermosetting compound 1: Phenol novolak type epoxy compound, “DEN431” manufactured by DOW, viscosity at 25°C 50 Pa·s (viscosity at 51.7°C 1.4 Pa·s)
Thermosetting compound 2: Phenol novolak type epoxy compound, "DEN438" manufactured by DOW, viscosity at 25°C 600 Pa・s or more (viscosity at 51.7°C 35.5 Pa・s)
Thermosetting compound 3: Bisphenol A type epoxy compound, “YD-8125” manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., viscosity at 25°C 0.173 Pa・s
Thermosetting compound 4: Bisphenol F type epoxy resin, “DER354” manufactured by DOW, viscosity at 25°C 3.8 Pa・s

Thermosetting component (hardening accelerator):
Curing accelerator 1: Boron trifluoride, "Boron trifluoride ethylamine complex" manufactured by Aldrich

Fatty acid amine salt:
Fatty acid amine salt 1: “Glutaric acid benzylamine salt”, melting point 108°C
Method for producing fatty acid amine salt 1:
24 g of water as a reaction solvent and 13.212 g of glutaric acid (manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a glass bottle and dissolved until uniform at room temperature. Then, 10.715 g of benzylamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred for about 5 minutes to obtain a mixed solution. The resulting mixture was placed in a refrigerator at 5 to 10°C and left overnight. The precipitated crystals were collected by filtration, washed with water, and vacuum dried to obtain fatty acid amine salt 1.

Fatty acid amide:
Fatty acid amide 1: “Glutaric acid benzylamide”, melting point 101°C
Method for preparing fatty acid amide 1:
13.212 g of glutaric acid (manufactured by Wako Pure Chemical Industries, Ltd.) and 10.715 g of benzylamine (manufactured by Wako Pure Chemical Industries, Ltd.) were placed in a three-necked flask and heated at 140° C. for 1 hour to react. Fatty acid amide 1 was obtained.

Solder particles:
Solder particles 1: SnAgCu solder particles, melting point 219°C, solder particles selected from "Sn96.5Ag3Cu0.5" manufactured by Mitsui Mining & Mining Co., Ltd., average particle size 30 μm
Solder particle 2: SnAgCu solder particles, melting point 219°C, solder particles selected from "Sn96.5Ag3Cu0.5" manufactured by Mitsui Mining & Mining Co., Ltd., average particle size 10 μm
Solder particles 3: SnAgCu solder particles, melting point 219°C, solder particles selected from "Sn96.5Ag3Cu0.5" manufactured by Mitsui Mining & Mining Co., Ltd., average particle size 3 μm
Solder particle 4: SnAgCu solder particles, melting point 219°C, solder particles selected from "Sn96.5Ag3Cu0.5" manufactured by Mitsui Mining & Mining Co., Ltd., average particle size 2 μm

solvent:
Solvent 1: 2-methyl-1,3-propanediol, "2-methyl-1,3-propanediol" manufactured by Tokyo Kasei Kogyo Co., Ltd., boiling point 214°C

(Viscosity of thermosetting compound at 25°C)
The viscosity of the thermosetting compound at 25° C. was measured at 25° C. and 5 rpm using an E-type viscometer (“TVE22L” manufactured by Toki Sangyo Co., Ltd.).

(Average particle diameter of solder particles)
The average particle diameter of the solder particles was measured using a laser diffraction particle size distribution analyzer (“LA-920” manufactured by Horiba, Ltd.).

(Melting point of solder particles)
The melting point of the solder particles was calculated using differential scanning calorimetry (DSC). As a differential scanning calorimetry (DSC) device, "EXSTAR DSC7020" manufactured by SII was used.

(Examples 1 to 9 and Comparative Examples 1 to 6)
(1) Preparation of conductive material (anisotropic conductive paste) A conductive material (anisotropic conductive paste) was obtained by blending the ingredients shown in Tables 1 and 2 below in the amounts shown in Tables 1 and 2 below. Ta.

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

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

On the upper surface of the glass epoxy substrate, a conductive material (anisotropic conductive paste) immediately after preparation was printed to a thickness of 100 μm by screen printing to form a conductive material (anisotropic conductive paste) layer. Next, a flexible printed circuit board was laminated on the upper surface of the conductive material (anisotropic conductive paste) layer so that the electrodes faced each other. The weight of the flexible printed circuit board is added to the conductive material (anisotropic conductive paste) layer. From this state, the conductive material (anisotropic conductive paste) layer was heated so that the temperature reached the melting point of the solder particles 5 seconds after the start of temperature rise. Furthermore, 15 seconds after the start of temperature rise, the conductive material (anisotropic conductive paste) layer is heated to a temperature of 200°C to harden the conductive material (anisotropic conductive paste) layer, and the connected structure is formed. Obtained. No pressure was applied during heating.

(3) Preparation of Connected Structure B Immediately after preparation, a conductive material (anisotropic conductive paste) was printed on the upper surface of the glass epoxy substrate to a thickness of 100 μm by screen printing. After that, screen printing was performed continuously 20 times. A connected structure B was produced in the same manner as the connected structure A except that a glass epoxy substrate on which a conductive material (anisotropic conductive paste) layer was formed by screen printing after 20 times was used.

(evaluation)
(1) Viscosity of conductive material The viscosity (ηA) of the obtained conductive material was calculated when measured at 25° C. and a shear rate of 600 sec ⁻¹ . Furthermore, the viscosity (ηB) of the obtained conductive material was calculated when measured under the conditions of 25° C. and a shear rate of 0.06 sec ⁻¹ . The above viscosity (ηA and ηB) was determined based on the following criteria.

The above viscosity (ηA and ηB) was measured using a rheometer (manufactured by Thermo Scientific, "HAAKE MARS III"). Specifically, it was measured as follows.

At a constant temperature of 25° C., a shear rate of 100 sec ⁻¹ was applied as a pre-shear for 60 seconds to the obtained conductive material, and then it was allowed to stand for 5 minutes. Next, the shear rate was changed from 0 sec ^-1 to 1000 sec ^-1 in 120 seconds, and then the shear rate was changed from 1000 sec ^-1 to 0 sec ^-1 in 120 seconds to perform measurements. In this measurement, when the shear rate was changed from 1000 sec ^-1 to 0 sec ^-1 in 120 seconds, the viscosity at a shear rate of 600 sec ^-1 was defined as ηA, and the viscosity at a shear rate of 0.06 sec ^-1 was defined as ηB.

[Judgement criteria for ηA]
○○: ηA is 5 Pa·s or more and 10 Pa·s or less ○: ηA is 1 Pa·s or more and less than 5 Pa·s, or more than 10 Pa·s and 20 Pa·s or less ×: ηA is less than 1 Pa·s or exceeding 20 Pa・s

[Judgement criteria for ηB]
○○: ηB is 2000 Pa・s or more and 3000 Pa・s or less ○: ηB is 1000 Pa・s or more and less than 2000 Pa・s, or more than 3000 Pa・s and 3500 Pa・s or less ×: ηB is less than 1000 Pa・s or more than 3500Pa・s

(2) Tanδ of conductive material
Regarding the obtained conductive material, tan δ was calculated when measured under the conditions of 25° C. and a frequency of 1 Hz. The above tan δ was determined based on the following criteria.

The tan δ was measured using a rheometer (“HAAKE MARS III” manufactured by Thermo Scientific). Specifically, it was measured as follows.

At a constant temperature of 25°C, the strain applied to the obtained conductive material was varied by sweeping from 0 to 100% at a frequency of 1 Hz, and the storage modulus (G') and loss modulus (G'') were determined, respectively. tan δ (G''/G') was calculated from the obtained storage modulus (G') and loss modulus (G'').

[Judgment criteria for tan δ]
○○: tan δ is 4 or more and 7 or less ○: tan δ is 2 or more and less than 4, or more than 7 and 10 or less ×: tan δ is less than 2 or more than 10

(3) Continuous Printability The obtained conductive material was screen printed on a slide glass using a metal mask with dimensions of 130 mm x 175 mm per opening and a thickness of 40 μm. Immediately after printing, the printed surface of the printed pattern was observed visually and with a stereomicroscope, and the dimensions were measured to determine whether bleeding or blurring had occurred. Continuous screen printing was performed to check the number of times printing could be performed without bleeding or blurring, and continuous printability was judged based on the following criteria.

[Judgment criteria for blurring or blurring]
[Bleeding]: Immediately after printing, there are areas that are 20% or more thicker than the plate dimensions. [Fading]: Immediately after printing, there are areas that are missing 20% or more compared to the plate dimensions.

[Continuous printing performance criteria]
○○: Can be printed 25 times or more without bleeding or blurring ○: Can be printed 11 or more times but less than 25 times without bleeding or blurring ×: Can be printed without bleeding or blurring Less than 11 times

(4) Accuracy of solder placement on the electrode (initial solder cohesion)
In the obtained connected structure A, when looking at the portion where the first electrode and the second electrode face each other in the stacking direction of the first electrode, the connecting portion, and the second electrode, the first electrode The ratio X of the area where the solder part in the connection part is arranged to 100% of the area of the opposing part of the electrode and the second electrode was evaluated. The placement accuracy of the solder on the electrode was judged based on the following criteria.

[Criteria for determining accuracy of solder placement on electrodes]
○○: Proportion X is 70% or more ○: Proportion X is 50% or more and less than 70% ×: Proportion X is less than 50%

(5) Solder placement accuracy on electrodes (solder cohesion after continuous printing)
In the obtained connected structure B, when looking at the portion where the first electrode and the second electrode face each other in the stacking direction of the first electrode, the connecting portion, and the second electrode, the first electrode The ratio Y of the area where the solder part in the connection part is arranged to 100% of the area of the opposing part of the electrode and the second electrode was evaluated. The placement accuracy of the solder on the electrode was judged based on the following criteria.

[Criteria for determining accuracy of solder placement on electrodes]
○○: Proportion Y is 70% or more ○: Proportion Y is 50% or more and less than 70% ×: Proportion Y is less than 50%

(6) Solder side balls In the obtained connection structure A, by observing the connection parts with a scanning electron microscope, solder side balls with a diameter of 100 μm or more or solder side balls with a diameter of less than 100 μm are formed around the connection parts. I checked to see if it was. Solder side balls were judged based on the following criteria.

[Judgment criteria for solder side balls with a diameter of 100 μm or more]
○○: No solder side balls with a diameter of 100 μm or more are formed around the connection. ○: The number of solder side balls with a diameter of 100 μm or more formed around the connection is 3 or less. ×: Around the connection. The number of solder side balls with a diameter of 100 μm or more formed on the

[Judgment criteria for solder side balls with a diameter of less than 100 μm]
○○: The number of solder side balls with a diameter of less than 100 μm formed around the connection part is 3 or less. ○: The number of solder side balls with a diameter of less than 100 μm formed around the connection part is more than 4. 10 or less ×: The number of solder side balls with a diameter of less than 100 μm formed around the connection exceeds 11.

(7) Continuity reliability (between upper and lower electrodes)
In the obtained connected structure A (20 pieces in total), the connection resistance per connection point between the upper and lower electrodes was measured using a four-terminal method. The average value of connection resistance was calculated. Note that from the relationship of voltage=current×resistance, the connection resistance can be determined by measuring the voltage when a constant current is passed. Continuity reliability was determined based on the following criteria.

[Criteria for determining continuity reliability]
○○: The average value of connection resistance is 50 mΩ or less. ○: The average value of connection resistance exceeds 50 mΩ and is 100 mΩ or less. ×: The average value of connection resistance exceeds 100 mΩ, or a connection failure has occurred.

(8) Insulation reliability (between horizontally adjacent electrodes)
In the 20 connected structures A obtained in the above (7) evaluation of continuity reliability, the presence or absence of leakage between adjacent electrodes was evaluated by measuring the resistance value with a tester. Insulation reliability was evaluated using the following criteria.

[Judgment criteria for insulation reliability]
○○: The number of connected structures with a resistance value of 10 ⁸ Ω or more is 18 or more ○: The number of connected structures with a resistance value of 10 ⁸ Ω or more is 10 or more and less than 18 ×: The resistance value is 10 The number of connected structures of ⁸ Ω or more is less than 10.

The results are shown in Tables 1 and 2 below.

Similar trends were observed even when flexible printed circuit boards, resin films, flexible flat cables, and rigid-flex circuit boards were used.

1, 1X... Connection structure 2... First connection target member 2a... First electrode 3... Second connection target member 3a... Second electrode 4, 4X... Connection part 4A, 4XA... Solder part 4B, 4XB ...Cured product part 11...Conductive material 11A...Solder particles 11B...Thermosetting component

Claims (8)

A conductive material containing a thermosetting component and a plurality of solder particles,
the thermosetting component includes a thermosetting compound,
The viscosity of the thermosetting compound at 25° C. is 3 Pa·s or more,
The conductive material does not contain a solvent, or contains 1% by weight or less of a solvent in 100% by weight of the conductive material,
The viscosity of the conductive material at 25° C. and a shear rate of 600 sec ⁻¹ is 1 Pa·s or more and 20 Pa·s or less,
The viscosity of the conductive material at 25° C. and a shear rate of 0.06 sec ⁻¹ is 1000 Pa·s or more and 3500 Pa·s or less,
The conductive material has a tan δ of 2 or more and 10 or less at 25° C. and a frequency of 1 Hz. The conductive material according to claim 1, comprising a fatty acid amine salt or a fatty acid amide. The conductive material according to claim 1 or 2, wherein the average particle diameter of the solder particles is 1 μm or more and 15 μm or less. The conductive material according to any one of claims 1 to 3, wherein the content of the solder particles is 40% by weight or more and 75% by weight or less in 100% by weight of the conductive material. 5. The conductive material according to claim 1, wherein the thermosetting compound has a viscosity of 3 Pa·s or more and 100 Pa·s or less at 25 °C. The conductive material according to any one of claims 1 to 5, which is a conductive paste. a first connection target member having a first electrode on its surface;
a second connection target member having a second electrode on its surface;
comprising a connection part connecting the first connection target member and the second connection target member,
The material of the connecting portion is the conductive material according to any one of claims 1 to 6,
A connection structure in which the first electrode and the second electrode are electrically connected by a solder part in the connection part. using the conductive material according to any one of claims 1 to 6, disposing the conductive material on the surface of the first connection target member having the first electrode on the surface;
A second connection target member having a second electrode on its surface is placed on a surface of the conductive material opposite to the first connection target member side, and the first electrode and the second electrode are opposite to each other. a step of arranging the
A connecting portion connecting the first connection target member and the second connection target member is formed from the conductive material by heating the conductive material to a temperature higher than the melting point of the solder particles, and A method for manufacturing a connected structure, comprising the step of electrically connecting the first electrode and the second electrode with a solder part in the connecting part.

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