JP7271312B2 - Conductive material, connection structure, and method for manufacturing connection structure - Google Patents

Description

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

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

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

For example, when electrically connecting an electrode of a flexible printed circuit board and an electrode of a glass epoxy board using the anisotropic conductive material, an anisotropic conductive material containing conductive particles is placed on the glass epoxy board. do. Next, the flexible printed circuit board is laminated and heated and pressurized. As a result, the anisotropic conductive material is cured and the electrodes are electrically connected via the conductive particles to obtain a connection structure.

As an example of the anisotropic conductive material, Patent Document 1 below discloses a conductive paste containing a thermosetting resin, a conductive filler, and a thixotropy imparting agent. In the conductive paste, the conductive filler is spherical or substantially spherical particles. In the conductive paste, the thixotropy-imparting agent is an organic acid or an organic onium salt. In the conductive paste, the thixotropy-imparting agent exists in the form of solid particles having an average particle size of 10 μm to 40 μm. Patent Literature 1 below describes that it is possible to suppress sedimentation of a filler during storage of a conductive paste and suppress dripping of the conductive paste.

In Patent Document 2 below, represented by the general formula AgxCuy (where 0.001 ≤ x ≤ 0.4, 0.6 ≤ y ≤ 0.999, x + y = 1 (atomic ratio)), and the particle surface A conductive paste is disclosed that includes a copper alloy powder having regions where the silver concentration is higher than the average silver concentration of the particles, a resin binder, and a solvent. The conductive paste contains a higher fatty acid or a higher fatty acid ester as a soldering improver. The content of the higher fatty acid or higher fatty acid ester with respect to 100 parts by weight of the copper alloy powder is 0.001 to 10 parts by weight. In Patent Document 2 below, as a solderability improving agent, a higher fatty acid is contained in a larger amount than a higher fatty acid ester, or only a higher fatty acid is contained, thereby increasing the thixotropy of the paste and suppressing the sedimentation of particles. It states that it is possible.

Patent Document 3 below discloses a conductive paste containing metal particles having an average particle size of 0.4 μm to 2.0 μm as a main component. In the metal particles, the number of metal particles having a particle size of 0.2 μm or less is 5% or less in 100% of the total number of the metal particles. In Patent Document 3 below, as a method for obtaining the conductive paste, metal particles having an average particle size of 0.4 μm to 2.0 μm are dispersed in an organic solvent to form a slurry, and then the slurry is left stationary for a certain period of time. A method of removing only the upper layer of the slurry to remove fine particles having a slow sedimentation velocity is described.

JP 2007-179772 A JP-A-10-031912 JP-A-10-134637

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 form a conductive connection. The conductive particles are preferably located between the top and bottom electrodes and not between adjacent lateral electrodes. It is desirable that there is no electrical connection between adjacent lateral electrodes.

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

In conventional conductive materials, when heated by reflow, etc., the viscosity of the thermosetting compound contained in the conductive material decreases before the solder particles reach the melting point, causing the conductive material to flow and change its shape. I have something to do. When the conductive material flows, the solder particles contained in the conductive material may move away from where they should be placed (for example, near the electrodes). Flowing of the conductive material may prevent efficient placement of the solder particles between the upper and lower electrodes to be connected. As a result, the solder particles contained in the conductive material are arranged in the regions where the electrodes are not formed, the amount of solder particles arranged between the upper and lower electrodes to be connected is reduced, and the upper and lower electrodes to be connected are arranged. In some cases, the reliability of electrical connection between electrodes may be lowered, or the reliability of insulation between adjacent lateral electrodes may be lowered. With conventional conductive materials, it is difficult to suppress the movement of solder particles due to the flow of the conductive material.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a conductive material that allows efficient placement of solder particles on electrodes. Another object of the present invention is to provide a connection structure using the conductive material and a method for manufacturing the connection structure.

According to a broad aspect of the present invention, the conductive material includes a thermosetting component, a plurality of solder particles, and flux, wherein the solder particles have an average particle size of 30 μm or less, and the conductive material is Provided is a conductive material in which the sedimentation rate of the solder particles when heated to 80°C at a temperature rate of 1°C/min and held at 80°C is 0.2 µm/s or more.

In a specific aspect of the conductive material according to the present invention, the sedimentation velocity of the solder particles of the conductive material at 25° C. is 0.02 μm/s or less.

In a specific aspect of the conductive material according to the present invention, the solder particles have an average particle size of less than 10 μm.

In a specific aspect of the conductive material according to the present invention, the flux has a melting point of 80° C. or less.

In a specific aspect of the conductive material according to the present invention, the solder particles have a specific gravity of 6 or more.

In a specific aspect of the conductive material according to the present invention, the conductive material has a viscosity at 25° C. of 50 Pa·s or more, and a viscosity at 80° C. of 10 Pa·s or less.

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

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

According to a broad aspect of the present invention, using the above-described conductive material, placing the conductive material on the surface of a first member to be connected having a first electrode on the surface; A second connection target member having a second electrode on its surface is arranged on the surface opposite to the first connection target member side such that the first electrode and the second electrode face each other. and heating the conductive material to a melting point of the solder particles or higher to form a connecting portion connecting the first member to be connected and the second member to be connected from the conductive material. and electrically connecting the first electrode and the second electrode with a solder portion in the connection portion.

A conductive material according to the present invention includes a thermosetting component, a plurality of solder particles, and a flux. In the conductive material according to the present invention, the solder particles have an average particle size of 30 μm or less. In the conductive material according to the present invention, when the conductive material is heated to 80°C at a temperature increase rate of 1°C/min and held at 80°C, the sedimentation rate of the solder particles is 0.2 μm/s or more. . Since the conductive material according to the present invention has the above configuration, it is possible to efficiently arrange the solder particles on the electrode.

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

The details of the present invention are described below.

(Conductive material)
A conductive material according to the present invention includes a thermosetting component, a plurality of solder particles, and a flux. In the conductive material according to the present invention, the solder particles have an average particle size of 30 μm or less. In the conductive material according to the present invention, when the conductive material is heated to 80°C at a temperature increase rate of 1°C/min and held at 80°C, the sedimentation rate of the solder particles is 0.2 μm/s or more. .

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

In conventional conductive materials, when heated by reflow, etc., the viscosity of the thermosetting compound contained in the conductive material decreases before the solder particles reach the melting point, causing the conductive material to flow and change its shape. I have something to do. When the conductive material flows, the solder particles contained in the conductive material may move away from where they should be placed (for example, near the electrodes). Flowing of the conductive material may prevent efficient placement of the solder particles between the upper and lower electrodes to be connected.

The present inventors focused on the sedimentation speed of solder particles and found that by using a specific conductive material, it is possible to suppress movement of the solder particles even if the conductive material flows. In the present invention, the solder particles can be sedimented at a relatively low temperature at which the flow of the conductive material occurs, the movement of the solder particles can be suppressed, and the solder particles can be arranged where they are originally arranged. In the present invention, even if the conductive material is heated by reflow or the like, the solder particles are sedimented to suppress movement of the solder particles, so that the solder particles can be efficiently arranged on the electrodes.

In addition, in the present invention, a plurality of solder particles tend to gather between the upper and lower facing electrodes at the time of conductive connection between the electrodes, and a plurality of solder particles can be arranged on the electrodes (lines). Also, some of the plurality of solder particles are less likely to be placed between the lateral electrodes that should not be connected, and the amount of solder particles placed between the lateral electrodes that should not be connected can be significantly reduced. can. As a result, in the present invention, it is possible to effectively improve the reliability of conduction between the upper and lower electrodes to be connected, and to effectively improve the reliability of insulation 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. In particular, solder particles with an average particle diameter of 30 μm or less tend to have a slow sedimentation velocity, so it is technically significant to control the sedimentation velocity of solder particles using a specific conductive material.

Furthermore, according to the present invention, positional displacement between electrodes can be prevented. In the present invention, when the second connection target member is superimposed on the first connection target member having the conductive material disposed on the upper surface, the electrode of the first connection target member and the electrode of the second connection target member Even if the alignment is misaligned, the electrodes can be connected by correcting the misalignment (self-alignment effect).

In the conductive material according to the present invention, the sedimentation speed (SV80) of the solder particles when the conductive material is heated to 80° C. at a temperature increase rate of 1° C./min and held at 80° C. is 0.2 μm/s. That's it. From the viewpoint of arranging the solder particles on the electrode more efficiently, the sedimentation velocity (SV80) of the solder particles is preferably 0.3 μm/s or more, more preferably 0.5 μm/s or more. The sedimentation velocity (SV80) of the solder particles is preferably 10 μm/s or less, more preferably 5 μm/s or less, still more preferably 3 μm/s or less.

The sedimentation velocity (SV80) of the solder particles can be measured by "Stability Tester ST-1" manufactured by Eiko Seiki Co., Ltd., or the like. Specifically, it can be measured as follows.

A sample tube containing a measurement sample is set in "Stability Tester ST-1" manufactured by Eko Seiki Co., Ltd. When the measurement is started, the stage on which the LED light source and the transmitted light and scattered light detectors are installed moves up and down along the sample tube, and the intensity distribution of transmitted light and backscattered light is measured. By repeating this measurement, the change in light intensity over time at each position in the sample tube can be observed. By converting this light intensity change per unit time, the sedimentation velocity of the solder particles can be calculated.

When measuring the sedimentation velocity (SV80) of the solder particles, it is preferable to heat from 25°C. In addition, when measuring the sedimentation velocity (SV80) of the solder particles, the conductive material is heated to 80°C at a heating rate of 1°C/min and held at 80°C. This heating condition is the heating condition for measuring the sedimentation velocity (SV80) of the solder particles in the present invention. When using the conductive material in the present invention, it is not necessary to heat under the above heating conditions.

Methods for adjusting the sedimentation velocity (SV80) of the solder particles to fall within the preferred range include a method for adjusting fluidity of the solder particles in the conductive material. Specific examples include a method of adjusting the viscosity of the conductive material, a method of adjusting solid matter (such as flux) in the conductive material, and a method of adjusting the specific gravity of the conductive material.

The sedimentation velocity (SV80) of the solder particles is not only determined by the viscosity of the conductive material, but also affected by solids (such as flux) in the conductive material. Specifically, even if the viscosity of the conductive material at 80° C. is relatively low, the presence of solids such as fillers and flux in the conductive material makes it difficult for the solder particles to settle. It is difficult to increase the sedimentation velocity (SV80) of solder particles.

From the viewpoint of arranging the solder particles on the electrode more efficiently, the sedimentation velocity (SV25) of the solder particles of the conductive material at 25° C. is preferably 0.02 μm/s or less, more preferably 0.02 μm/s or less. 01 μm/s or less.

The sedimentation velocity (SV25) of the solder particles of the conductive material at 25° C. can be measured with a “stability tester ST-1” manufactured by Eko Seiki Co., Ltd., or the like.

Methods for adjusting the sedimentation velocity (SV25) of the solder particles of the conductive material at 25° C. within the preferred range include a method for adjusting fluidity of the solder particles in the conductive material. Specific examples include a method of adjusting the viscosity of the conductive material, a method of adjusting the solid matter (such as flux) of the conductive material, and a method of adjusting the specific gravity of the conductive material.

From the viewpoint of arranging the solder particles on the electrode more efficiently, the viscosity (η25) of the conductive material at 25° C. is preferably 30 Pa s or more, more preferably 50 Pa s or more, and preferably It is 400 Pa·s or less, more preferably 300 Pa·s or less. The viscosity (η25) can be appropriately adjusted depending on the types and amounts of ingredients to be blended.

The viscosity (η25) 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 more efficiently arranging the solder particles on the electrode, the viscosity (η80) of the conductive material at 80° C. is preferably 3 Pa s or more, more preferably 5 Pa s or more, and preferably It is 10 Pa·s or less, more preferably 8 Pa·s or less. The viscosity (η80) can be appropriately adjusted depending on the type and amount of compounding components.

The viscosity (η80) is measured using, for example, a rheometer "HAAKE MARS III" manufactured by Thermo Fisher Scientific under the conditions of a frequency of 2 Hz, a temperature increase rate of 0.11°C/sec, and a measurement temperature range of 40°C to 200°C. It is possible. In this measurement, the viscosity at 80°C is defined as η80.

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

Each component contained in the conductive material will be described below. In this specification, "(meth)acryl" means one or both of "acryl" and "methacryl".

(solder particles)
Both the central portion and the outer surface of the solder particles are formed of solder. The solder particles are particles in which both the central portion and the outer surface are solder. Instead of the solder particles, when using conductive particles comprising base particles formed of a material other than solder and solder portions disposed on the surfaces of the base particles, conductive particles are formed on the electrodes. It becomes difficult for particles to gather. In addition, since the conductive particles have low solderability between the conductive particles, the conductive particles that have moved onto the electrodes tend to move out of the electrodes. tends to be lower.

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

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

Also, the solder particles preferably contain tin. The content of tin in 100% by weight of the metal contained in the solder particles 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. . When the content of tin in the solder particles is equal to or higher than the lower limit, reliability of conduction and reliability of connection between the solder portion and the electrode are further enhanced.

The tin content can be determined using a high-frequency inductively coupled plasma atomic emission spectrometer (“ICP-AES” manufactured by Horiba Ltd.) or a fluorescent X-ray spectrometer (“EDX-800HS” manufactured by Shimadzu Corporation). can be measured.

By using the solder particles, the solder is melted and joined to the electrodes, and the solder portions conduct between the electrodes. For example, since the solder part and the electrode are likely to be in surface contact rather than point contact, the connection resistance is reduced. In addition, the use of the solder particles increases the bonding strength between the solder portion and the electrode, making it more difficult for the solder portion and the electrode to separate, thereby further increasing the conduction reliability and connection reliability.

The low-melting-point metal forming the solder particles is not particularly limited. The low melting point metal is preferably tin or an alloy containing tin. The alloys include tin-silver alloys, tin-copper alloys, tin-silver-copper alloys, tin-bismuth alloys, tin-zinc alloys, tin-indium alloys, and the like. The low-melting-point metal is preferably tin, a tin-silver alloy, a tin-silver-copper alloy, a tin-bismuth alloy, or a tin-indium alloy because of its excellent wettability with the electrode. More preferably, the low melting point metal is a tin-bismuth alloy or a tin-indium alloy.

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

In order to further increase the bonding strength between the solder part and the electrode, the solder particles contain nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth, manganese, chromium, Metals such as molybdenum and palladium may also be included. Moreover, from the viewpoint of further increasing the bonding strength between the solder portion and the electrode, the solder particles preferably contain nickel, copper, antimony, aluminum, or zinc. From the viewpoint of further 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. It is preferably 1% by weight or less.

In the conductive material according to the present invention, the solder particles have an average particle size of 30 μm or less. The average particle size of the solder particles is preferably 1 μm or more, more preferably 2 μm or more, still more preferably 3 μm or more, preferably 20 μm or less, more preferably 10 μm or less, still more preferably less than 10 μm, particularly preferably 7 μm or less. is. When the average particle size of the solder particles is equal to or more than the lower limit and equal to or less than the upper limit, the solder particles can be arranged on the electrode more efficiently. It is particularly preferable that the solder particles have an average particle size of 3 μm or more and 10 μm or less. In the conductive material according to the present invention, the smaller the average particle size of the solder particles, the more effectively the above effects of the present invention are exhibited. That is, in the conductive material according to the present invention, the smaller the average particle diameter of the solder particles, the more efficiently the solder particles can be arranged on the electrodes, and the reliability of conduction between the upper and lower electrodes to be connected is improved. can be effectively increased, and the insulation reliability between adjacent lateral electrodes that should not be connected can be effectively increased.

The average particle size of the solder particles is preferably the number average particle size. The average particle size of the solder particles can be obtained, for example, by observing 50 arbitrary solder particles with an electron microscope or an optical microscope and calculating the average particle size of each solder particle, or by laser diffraction particle size distribution measurement. It is required by doing. In observation with an electron microscope or an optical microscope, the particle size of a single solder particle is obtained as the particle size of the equivalent circle diameter. In observation with an electron microscope or an optical microscope, the average particle size of arbitrary 50 solder particles in the equivalent circle diameter is approximately equal to the average particle size in the equivalent sphere diameter. In the laser diffraction particle size distribution measurement, the particle size of one solder particle is determined as the particle size in terms of equivalent sphere diameter. The average particle size 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 size of the solder particles is equal to or greater than the lower limit and equal to or less than the upper limit, the solder particles can be arranged on the electrode more efficiently. However, the CV value of the particle diameter of the solder particles may be less than 5%.

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

CV value (%) = (ρ/Dn) × 100
ρ: standard deviation of particle size of solder particles Dn: average value of particle size of solder particles

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

From the viewpoint of arranging the solder particles on the electrode more efficiently, the specific gravity of the solder particles is preferably 6 or more, more preferably 7 or more, and still more preferably 8 or more.

The specific gravity of the solder particles is determined by, for example, "Accupic II 1340" manufactured by Shimadzu Corporation.

In 100% by weight of the conductive material, the content of the solder particles is preferably 50% by weight or more, more preferably 55% by weight or more, still more preferably 60% by weight or more, particularly preferably 65% by weight or more, and most preferably 70% by weight or more. The content of the solder particles in 100% by weight of the conductive material is preferably 90% by weight or less, more preferably 85% by weight or less, even more preferably 80% by weight or less, and particularly preferably 75% by weight or less. When the content of the solder particles is the lower limit or more and the upper limit or less, the solder particles can be arranged on the electrodes more efficiently, and it is easy to arrange a large amount of solder between the electrodes, Conductivity reliability is further enhanced. From the standpoint of further improving conduction reliability, the content of the solder particles is preferably large.

(Thermosetting component)
The electrically conductive material according to the invention comprises a thermosetting component. The conductive material may contain 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.

(Thermosetting component: thermosetting compound)
The thermosetting compound is not particularly limited. Examples of the thermosetting compounds 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, the viewpoint of further effectively improving the conduction reliability, and the viewpoint of further effectively improving the insulation reliability, the thermosetting compound is Epoxy compounds or episulfide compounds are preferred, and epoxy compounds are more preferred. The thermosetting compound preferably contains an epoxy compound. As for the said thermosetting compound, only 1 type may be used and 2 or more types may be used together.

The epoxy compound is a compound having at least one epoxy group. Examples of the epoxy compounds include bisphenol A type epoxy compounds, bisphenol F type epoxy compounds, bisphenol S type epoxy compounds, phenol novolac 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 adamantane skeleton, epoxy compound having tricyclodecane skeleton, naphthylene ether type Epoxy compounds, epoxy compounds having a triazine core in the skeleton, and the like are included. Only one type of the epoxy compound may be used, or two or more types may be used in combination.

The epoxy compound is liquid or solid at normal temperature (23° C.), and when the epoxy compound is solid at normal 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 of bonding the connection target members, and when acceleration is applied due to impact such as transportation, the first connection target member and the second connection Positional deviation from the target member can be suppressed. Furthermore, the heat during curing can greatly reduce the viscosity of the conductive material, allowing the agglomeration of the solder particles to proceed efficiently.

From the viewpoint of more effectively improving insulation reliability and more effectively improving conduction reliability, the thermosetting component preferably contains an epoxy compound, and the thermosetting compound contains an epoxy compound. preferably included.

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

As the thermosetting compound having a polyether skeleton, a compound having a glycidyl ether group at both ends of an alkyl chain having 3 to 12 carbon atoms, and a polyether skeleton having 2 to 4 carbon atoms, the polyether skeleton Examples thereof include polyether type epoxy compounds having a structural unit in which 2 to 10 are continuously bonded.

From the viewpoint of more 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 isocyanurate skeleton include triisocyanurate type epoxy compounds, and 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) and the like.

The content of the thermosetting compound in 100% by weight of the conductive material is preferably 20% by weight or more, more preferably 40% by weight or more, still more preferably 50% by weight or more, and preferably 99% by weight or less. It is preferably 98% by weight or less, more preferably 90% by weight or less, and particularly preferably 80% by weight or less. When the content of the thermosetting compound is equal to or more than the lower limit and equal to or less than the upper limit, the solder particles can be arranged on the electrodes more efficiently, and the insulation reliability between the electrodes can be more effectively improved. It is possible to more effectively improve the reliability of electrical connection between the electrodes. From the viewpoint of more effectively increasing the impact resistance, the content of the thermosetting compound is preferably large.

The content of the epoxy compound in 100% by weight of the conductive material is preferably 20% by weight or more, more preferably 40% by weight or more, still more preferably 50% by weight or more, and preferably 99% by weight or less, more preferably It is 98% by weight or less, more preferably 90% by weight or less, and particularly preferably 80% by weight or less. When the content of the epoxy compound is equal to or more than the lower limit and equal to or less than the upper limit, the solder particles can be arranged on the electrodes more efficiently, and the insulation reliability between the electrodes can be more effectively improved. It is possible to further effectively improve the reliability of electrical connection between the electrodes. From the viewpoint of further increasing the impact resistance, the content of the epoxy compound is preferably large.

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

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

The imidazole curing agent is not particularly limited. Examples of the imidazole curing agent include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6. -[2′-methylimidazolyl-(1′)]-ethyl-s-triazine and 2,4-diamino-6-[2′-methylimidazolyl-(1′)]-ethyl-s-triazine isocyanuric acid adducts , 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4-benzyl-5-hydroxymethylimidazole, 2-p-toluyl-4-methyl-5 -5-position of 1H-imidazole in hydroxymethylimidazole, 2-methatoluyl-4-methyl-5-hydroxymethylimidazole, 2-methatoluyl-4,5-dihydroxymethylimidazole, 2-paratoluyl-4,5-dihydroxymethylimidazole, etc. and the hydrogen at the 2-position is substituted with a hydroxymethyl group and the hydrogen at the 2-position with a phenyl group or a toluyl group.

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

The acid anhydride curing agent is not particularly limited, and a wide range of acid anhydrides can be used as long as they are used as curing agents for thermosetting compounds such as epoxy compounds. Examples of the acid anhydride curing agent include phthalic anhydride, tetrahydrophthalic anhydride, trialkyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and methylbutenyltetrahydrophthalic anhydride. , anhydrides of phthalic acid derivatives, maleic anhydride, nadic anhydride, methyl nadic anhydride, glutaric anhydride, succinic anhydride, glycerin bis trimellitic anhydride monoacetate, and ethylene glycol bis trimellitic anhydride. acid anhydride curing agent, trifunctional acid anhydride curing agent such as trimellitic anhydride, and pyromellitic anhydride, benzophenone tetracarboxylic anhydride, methylcyclohexene tetracarboxylic anhydride, polyazelaic anhydride, etc. and a tetrafunctional or higher acid anhydride curing agent.

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 cationic curing agent include bis(4-tert-butylphenyl)iodonium hexafluorophosphate. Examples of the oxonium cationic curing agent include trimethyloxonium tetrafluoroborate. Examples of the sulfonium cationic curing agent include tri-p-tolylsulfonium hexafluorophosphate.

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

The reaction initiation temperature of the thermosetting agent is preferably 50°C or higher, more preferably 70°C or higher, still more preferably 80°C or higher, preferably 250°C or lower, more preferably 200°C or lower, and still more preferably 150°C. Below, it is 140 degrees C or less especially preferably. When the reaction initiation temperature of the heat curing agent is equal to or higher than the lower limit and equal to or lower than the upper limit, the solder particles are arranged on the electrode more efficiently. It is particularly preferable that the reaction initiation temperature of the thermosetting agent is 80° C. or higher and 140° C. or lower.

From the viewpoint of more efficiently arranging the solder particles on the electrodes, the reaction initiation temperature of the thermosetting agent is preferably higher than the melting point of the solder particles, more preferably 5° C. or higher. ° C. or more is more preferable.

The reaction initiation temperature of the thermosetting agent means the temperature at which the exothermic peak starts to rise in differential scanning calorimetry (DSC).

The content of the thermosetting agent is not particularly limited. With respect to 100 parts by weight of the thermosetting compound, the content of the thermosetting agent is preferably 0.01 parts by weight or more, more preferably 1 part by weight or more, and preferably 200 parts by weight or less, more preferably It 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 harden the conductive material. When the content of the thermosetting agent is equal to or less than the above upper limit, it becomes difficult for excess thermosetting agent that has not been involved in curing to remain after curing, and the heat resistance of the cured product is further enhanced.

(flux)
A conductive material according to the present invention includes a flux. The above flux is not particularly limited. Flux generally used for soldering or the like can be used as the flux. The flux is preferably the above-described organic acid or a salt thereof. The flux may contain compounds other than the above-described organic acids or salts thereof.

Examples of the flux include zinc chloride, mixtures of zinc chloride and inorganic halides, mixtures of zinc chloride and inorganic acids, molten salts, phosphoric acid, phosphoric acid derivatives, organic halides, hydrazine, amine compounds, organic acids and pine resin and the like. Only one kind of the above flux may be used, or two or more kinds thereof may be used in combination.

Examples of the molten salt include ammonium chloride. Examples of the organic acid 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 rosin. The flux may be an organic acid having two or more carboxyl groups, or may be rosin. The use of rosin, an organic acid having two or more carboxyl groups, further enhances the reliability of electrical connection between electrodes.

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

The pine resin is a rosin containing abietic acid as a main component. Examples of the rosins include abietic acid and acryl-modified rosins. The flux is preferably rosins, more preferably abietic acid. By using this preferable flux, the reliability of electrical connection between electrodes can be improved more effectively.

The melting point (activation temperature) of the flux is preferably 50° C. or higher, more preferably 60° C. or higher, and preferably 80° C. or lower, more preferably 70° C. or lower. When the melting point of the flux is equal to or higher than the lower limit and equal to or lower than the upper limit, the solder particles can be arranged on the electrode even more efficiently.

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

The flux is preferably liquid at 25°C. Since the flux is liquid at 25° C., the solder particles can be arranged on the electrodes more efficiently.

Flux that is liquid at 25° C. is not particularly limited. The flux is preferably an acidic phosphate ester compound. Commercially available acidic phosphate compounds include ethyl acid phosphate and butyl acid phosphate (both of which are manufactured by Johoku Kagaku Kogyo Co., Ltd.).

Also, the boiling point of the flux is preferably 200° C. or lower.

The flux may be dispersed in the conductive material or adhered to the surfaces of the solder particles.

From the viewpoints of more efficiently arranging solder particles on the electrodes, more effectively improving insulation reliability, and more effectively improving conduction reliability, the flux contains an acid compound and a base. A salt with a compound is preferable, and an organic phosphorus compound is more preferable.

From the viewpoint of arranging the solder particles on the electrode more efficiently, the organic phosphorus compound is an organic phosphonium salt, an organic phosphoric acid, an organic phosphoric acid ester, an organic phosphonic acid, an organic phosphonic acid ester, an organic phosphinic acid, or It is preferably an organic phosphinate. From the viewpoint of arranging the solder particles on the electrode more efficiently, the organic phosphorus compound is more preferably an organic phosphonium salt.

Examples of the organic phosphonium salts include organic phosphonium salts composed of a phosphonium ion and its counterion. Commercially available products of the above organic phosphonium salts include "Hishikorin" series manufactured by Nippon Kagaku Kogyo Co., Ltd., and the like. Only one of the above organic phosphonium salts may be used, or two or more thereof may be used in combination.

The organic phosphoric acid, the organic phosphoric acid ester, the organic phosphonic acid, the organic phosphonic acid ester, the organic phosphinic acid, and the organic phosphinic acid ester are not particularly limited, and conventionally known compounds and commercially available products can be used. can be done. Only one of these may be used, or two or more thereof may be used in combination.

From the viewpoint of arranging the solder particles on the electrode more efficiently, the organophosphorus compound is preferably liquid at 25°C.

From the viewpoint of more efficiently arranging solder particles on the electrodes, from the viewpoint of more effectively increasing the reliability of insulation between adjacent electrodes, and from the viewpoint of more effectively improving the reliability of conduction between the upper and lower electrodes to be connected. From the viewpoint of increasing the concentration, the organic phosphorus compound is preferably methyltributylphosphonium, dimethylphosphate, or tetrabutylphosphonium bromide.

The content of the organic phosphorus 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 or less. When the content of the organic phosphorus compound is equal to or more than the lower limit and equal to or less than the upper limit, the solder particles can be arranged on the electrode more efficiently.

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. Examples of the acid compound include aliphatic carboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, citric acid, malic acid, and cycloaliphatic carboxylic acids. Examples include cyclohexylcarboxylic acid, 1,4-cyclohexyldicarboxylic acid, isophthalic acid which is an aromatic carboxylic acid, terephthalic acid, trimellitic acid, and ethylenediaminetetraacetic acid. From the viewpoint of more efficiently arranging the solder particles on the electrode, more effectively improving the insulation reliability, and more effectively improving the conduction reliability, the acid compound is glutaric acid, Cyclohexylcarboxylic acid or adipic acid are preferred.

The basic compound is preferably an organic compound having an amino group. Examples of the base compound include diethanolamine, triethanolamine, methyldiethanolamine, ethyldiethanolamine, cyclohexylamine, dicyclohexylamine, benzylamine, benzhydrylamine, 2-methylbenzylamine, 3-methylbenzylamine, 4-tert-butylbenzylamine. , N-methylbenzylamine, N-ethylbenzylamine, N-phenylbenzylamine, N-tert-butylbenzylamine, N-isopropylbenzylamine, N,N-dimethylbenzylamine, imidazole compounds, and triazole compounds. . From the viewpoints of more efficiently arranging the solder particles on the electrodes, more effectively improving the insulation reliability, and more effectively improving the conduction reliability, the base compound is benzylamine. Preferably.

The flux content in 100% by weight of the conductive material is preferably 0.5% by weight or more, preferably 30% by weight or less, and more preferably 25% by weight or less. The conductive material may not contain flux. When the content of the flux is at least the lower limit and at most the upper limit, it becomes more difficult to form an oxide film on the surface of the solder and the electrode, and furthermore, the oxide film formed on the surface of the solder and the electrode is further removed. can be removed effectively.

(filler)
The conductive material according to the present invention may contain filler. The filler may be an organic filler or an inorganic filler. By including the filler in the conductive material, the solder particles can be uniformly agglomerated on all the electrodes of the substrate.

Preferably, the conductive material does not contain the filler, or contains the filler in an amount of 5% by weight or less. When the thermosetting compound is used, the smaller the content of the filler, the easier it is for the solder particles to move onto the electrode.

The content of the filler in 100% by weight of the conductive material is preferably 0% by weight (not included) or more, preferably 5% by weight or less, more preferably 2% by weight or less, and further preferably 1% by weight or less. be. When the content of the filler is equal to or more than the lower limit and equal to or less than the upper limit, the solder particles are arranged more uniformly on the electrode.

(other ingredients)
The above-mentioned conductive material may optionally include fillers, extenders, softeners, plasticizers, thixotropic agents, leveling agents, polymerization catalysts, curing catalysts, colorants, antioxidants, heat stabilizers, light stabilizers, , ultraviolet absorbers, lubricants, antistatic agents and flame retardants.

(Connection structure and method for manufacturing the connection structure)
A connection structure according to the present invention includes a first connection object member having a first electrode on the surface, a second connection object member having a second electrode on the surface, the first connection object member, and a connecting portion connecting the second member to be connected. In the connection structure according to the present invention, the material of the connection portion is the above-described conductive material. In the connection structure according to the present invention, the first electrode and the second electrode are electrically connected by a solder portion in the connection portion.

A method for manufacturing a connected structure according to the present invention includes the step of placing the conductive material on the surface of the first member to be connected having the first electrode on the surface thereof, using the conductive material described above. In the method for manufacturing a connected structure according to the present invention, a second member to be connected having a second electrode on the surface thereof is formed on the surface of the conductive material opposite to the first member to be connected. A step of arranging the one electrode and the second electrode so as to face each other. In the method for manufacturing a connected structure according to the present invention, the first member to be connected and the second member to be connected are connected by heating the conductive material to the melting point of the solder particles or higher. forming a section from the conductive material, and electrically connecting the first electrode and the second electrode by a solder section in the connecting section.

In the connection structure and the method for manufacturing the connection structure according to the present invention, since the specific conductive material is used, the solder particles tend to gather between the first electrode and the second electrode, and the solder particles line). In addition, some of the solder particles are less likely to be placed in areas (spaces) where electrodes are not formed, and the amount of solder particles placed in areas where electrodes are not formed can be significantly reduced. Therefore, reliability of conduction between the first electrode and the second electrode can be improved. Moreover, it is possible to prevent electrical connection between laterally adjacent electrodes, which should not be connected, and improve insulation reliability.

Further, in order to efficiently arrange the solder particles on the electrodes and to considerably reduce the amount of the solder particles arranged in the areas where the electrodes are not formed, the conductive material is not a conductive film but a conductive paste. is preferably used.

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

In the method for manufacturing a connected structure according to the present invention, pressure is not applied in the step of arranging the second member to be connected and the step of forming the connecting portion, and the second connection is not applied to the conductive material. 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 does not have the force of the weight of the second member to be connected. It is preferable not to apply a pressure exceeding . In these cases, it is possible to further improve the uniformity of the amount of solder in the plurality of solder portions. In addition, the thickness of the solder portion can be increased more effectively, a plurality of solder particles can easily gather between the electrodes, and a plurality of solder particles can be more efficiently arranged on the electrodes (lines). can. In addition, some of the plurality of solder particles are less likely to be arranged in areas (spaces) where electrodes are not formed, and the amount of solder in the solder particles arranged in areas where electrodes are not formed can be further reduced. can. Therefore, it is possible to further improve the reliability of electrical connection between the electrodes. Moreover, it is possible to further prevent electrical connection between laterally adjacent electrodes that should not be connected, thereby further enhancing insulation reliability.

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

A connection structure 1 shown in FIG. a part 4; The connecting portion 4 is made of the conductive material described above. In this embodiment, the conductive material includes a thermosetting component, solder particles, and flux. The thermosetting component includes a thermosetting compound and a thermosetting agent. In this embodiment, a conductive paste is used as the conductive material.

The connection portion 4 has a solder portion 4A in which a plurality of solder particles are gathered and joined together, and a cured product portion 4B in which a thermosetting compound is thermally cured.

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 its 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. In the connecting portion 4, solder particles do not exist in a region (hardened material portion 4B portion) different from the solder portion 4A gathered between the first electrode 2a and the second electrode 3a. In a region different from the solder portion 4A (hardened material portion 4B portion), there are no solder particles separated from the solder portion 4A. If the amount is small, the solder particles may be present in a region (cured material portion 4B portion) different from the solder portion 4A gathered between the first electrode 2a and the second electrode 3a.

As shown in FIG. 1, in the connection structure 1, a plurality of solder particles gather between the first electrode 2a and the second electrode 3a. Wet and spread the surface of the electrode and then solidify to form the solder portion 4A. Therefore, the connection areas between the solder portion 4A and the first electrode 2a and between the solder portion 4A and the second electrode 3a are increased. That is, by using solder particles, the solder portion 4A and the first electrode 2a, as well as the solder portion, are compared with the case where the conductive outer surface is a metal such as nickel, gold or copper. The contact area between 4A and the second electrode 3a is increased. This also increases the conduction reliability and connection reliability in the connection structure 1 . In addition, when flux is contained in the conductive material, the flux is generally gradually deactivated by heating.

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

If the amount of solder particles used is reduced, it becomes easier to obtain the connection structure 1 . If the amount of solder particles used is increased, it becomes easier to obtain the connection structure 1X.

In the connection structures 1, 1X, when the first electrode 2a, the connection portion 4, 4X, and the second electrode 3a are stacked in the direction in which the first electrode 2a and the second electrode 3a face each other, Furthermore, it is preferable that the solder portions 4A and 4XA in the connection portions 4 and 4X are arranged in 50% or more of the 100% area of the portion where the first electrode 2a and the second electrode 3a face each other. . When the solder portions 4A and 4XA in the connection portions 4 and 4X satisfy the above preferred aspects, the electrical connection reliability can be further enhanced.

When the facing portion of the first electrode and the second electrode is viewed 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 arranged in 50% or more of 100% of the area of the portion facing the two electrodes. When the facing portion of the first electrode and the second electrode is viewed in the stacking direction of the first electrode, the connecting portion, and the second electrode, the first electrode and the second electrode More preferably, the solder portion in the connecting portion is arranged in 60% or more of 100% of the area of the portion facing the two electrodes. When the facing portion of the first electrode and the second electrode is viewed in the stacking direction of the first electrode, the connecting portion, and the second electrode, the first electrode and the second electrode More preferably, the solder portion in the connecting portion is arranged in 70% or more of 100% of the area of the portion facing the two electrodes. When the facing portion of the first electrode and the second electrode is viewed 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 arranged in 80% or more of 100% of the area of the portion facing the two electrodes. When the facing portion of the first electrode and the second electrode is viewed 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 portion in the connection portion is arranged in 90% or more of 100% of the area of the portion facing the two electrodes. When the solder portion in the connection portion satisfies the above-mentioned preferred aspects, the reliability of conduction can be further improved.

When a portion of the first electrode and the second electrode facing each other is viewed in a direction orthogonal to the lamination direction of the first electrode, the connecting portion, and the second electrode, the first electrode It is preferable that 60% or more of the solder portion in the connection portion is arranged in the portion where the electrode and the second electrode face each other. When a portion of the first electrode and the second electrode facing each other is viewed in a direction orthogonal to the lamination direction of the first electrode, the connecting portion, and the second electrode, the first electrode More preferably, 70% or more of the solder portion in the connection portion is arranged in the portion where the electrode and the second electrode face each other. When a portion of the first electrode and the second electrode facing each other is viewed in a direction orthogonal to the lamination direction of the first electrode, the connecting portion, and the second electrode, the first electrode More preferably, 90% or more of the solder portion in the connection portion is arranged in the portion where the electrode and the second electrode face each other. When a portion of the first electrode and the second electrode facing each other is viewed in a direction orthogonal to the lamination direction of the first electrode, the connecting portion, and the second electrode, the first electrode It is particularly preferable that 95% or more of the solder portion in the connection portion is arranged in the portion where the electrode and the second electrode face each other. When a portion of the first electrode and the second electrode facing each other is viewed in a direction orthogonal to the lamination direction of the first electrode, the connecting portion, and the second electrode, the first electrode Most preferably, 99% or more of the solder portion in the connecting portion is arranged in the portion where the electrode and the second electrode face each other. When the solder portion in the connection portion satisfies the above-mentioned preferred aspects, the reliability of conduction can be further improved.

Next, with reference to FIG. 2, an example of a method of manufacturing the connection structure 1 using the conductive material according to one embodiment of the present invention will be described.

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

A conductive material 11 is arranged on the surface of the first connection target member 2 on which the first electrode 2a is provided. After the placement of the conductive material 11, the solder particles 11A are placed both on the first electrodes 2a (lines) and on the regions (spaces) where the first electrodes 2a are not formed.

The method of arranging the conductive material 11 is not particularly limited, but examples thereof include application using a dispenser, screen printing, and ejection using an inkjet device.

Also, a second connection object member 3 having a second electrode 3a on its surface (lower surface) is prepared. Next, as shown in FIG. 2(b), on the surface of the conductive material 11 on the surface of the first connection target member 2, on the surface opposite to the first connection target member 2 side of the conductive material 11, A second member to be connected 3 is arranged (second step). The second member 3 to be connected is arranged on the surface of the conductive material 11 from the side of the second electrode 3a. At this time, the first electrode 2a and the second electrode 3a are opposed to each other.

Next, the conductive material 11 is heated above the melting point of the solder particles 11A (third step). Preferably, the conductive material 11 is heated to the curing temperature of the thermosetting component 11B (thermosetting compound) or higher. During this heating, the solder particles 11A existing in the regions where no electrodes are formed gather between the first electrode 2a and the second electrode 3a (self-aggregation effect). When a conductive paste is used instead of the conductive film, the solder particles 11A gather more effectively between the first electrode 2a and the second electrode 3a. Also, the solder particles 11A are melted and joined together. Also, the thermosetting component 11B is thermoset. As a result, as shown in FIG. 2(c), the connecting portion 4 connecting the first connection target member 2 and the second connection target member 3 is formed of the conductive material 11. Next, as shown in FIG. The connecting portion 4 is formed of the conductive material 11, the solder portion 4A is formed by joining a plurality of solder particles 11A, and the cured product portion 4B is formed by thermally curing 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 to move, and then the first electrode 2a and the second electrode It is not necessary to keep the temperature constant until the movement of the solder particles 11A between the solder particles 3a is completed.

In this embodiment, since the specific conductive material 11 is used, the solder particles 11A can be sedimented at a relatively low temperature at which the conductive material 11 flows. Solder particles 11A can be placed where they are placed (on the electrodes). As a result, the solder particles 11A can be arranged more efficiently between the electrodes to be connected, and the reliability of conduction and reliability of insulation can be more effectively improved.

In the present embodiment, it is preferable not to pressurize in the second step and the third step. In this case, the weight of the second member 3 to be connected is added to the conductive material 11 . Therefore, the solder particles 11A gather more effectively between the first electrode 2a and the second electrode 3a when forming the connecting portion 4. As shown in FIG. In at least one of the second step and the third step, when pressure is applied, the solder particles 11A tend to gather between the first electrode 2a and the second electrode 3a. are more likely to be inhibited.

Further, in the present embodiment, since no pressure is applied, the first connection object member 2 and the second connection object member 3 are connected in a state in which the first electrode 2a and the second electrode 3a are out of alignment. are superimposed on each other, the deviation can be corrected and the first electrode 2a and the second electrode 3a can be connected (self-alignment effect). This is because the molten solder that is self-coalescing between the first electrode 2a and the second electrode 3a is removed from the solder and other conductive material between the first electrode 2a and the second electrode 3a. This is because the smaller the area in contact with the component is, the more stable the energy is, and the force acts to make the connection structure having the minimum area, which is the connection structure with alignment. At this time, it is desirable that the conductive material is not hardened and that the viscosity of the components other than the solder particles of the conductive material is sufficiently low at that temperature and time.

The viscosity (ηmp) of the conductive material at the melting point of the solder particles is preferably 50 Pa s or less, more preferably 10 Pa s or less, still more preferably 1 Pa s or less, and preferably 0.1 Pa s or more. It is preferably 0.2 Pa·s or more. When the viscosity (ηmp) is equal to or less than the upper limit, the solder particles can be efficiently agglomerated on the electrode. When the viscosity is equal to or higher than the lower limit, it is possible to suppress the formation of voids at the connecting portion and suppress the protrusion of the conductive material to areas other than the connecting portion.

The viscosity (ηmp) is measured, for example, using a rheometer "HAAKE MARS III" manufactured by Thermo Fisher Scientific Co., Ltd., with a frequency of 2 Hz, a temperature increase rate of 0.11 ° C./sec, and a measurement temperature range of 25 ° C. to 200 ° C. (however, solder If the melting point of the particles exceeds 200° C., the melting point of the solder particles is used as the upper limit of the temperature). From the measurement results, the viscosity at the melting point (° C.) of the solder particles is evaluated.

Thus, the connection structure 1 shown in FIG. 1 is obtained. Note that the second step and the third step may be performed continuously. Further, after performing the second step, the obtained laminate of the first connection object member 2, the conductive material 11, and the second connection object member 3 is moved to the heating unit, and the third step is performed. process may be performed. To perform the heating, the laminate may be placed on a heating member, or the laminate may be placed in a heated space.

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

As the heating method in the third step, a method of heating the entire connection structure using a reflow furnace or an oven to a temperature above the melting point of the solder particles and above the curing temperature of the thermosetting component, or a method of heating the connection structure A method of locally heating only the connection part of the body is mentioned.

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

Also, when locally heating with a hot plate, use a metal with high thermal conductivity just below the connection part, and use a material with low thermal conductivity such as fluororesin for other places that are not desirable to heat. , preferably forming a hot plate top surface.

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

At least one of the first member to be connected and the second member to be connected is preferably a resin film, a flexible printed board, a flexible flat cable, or a rigid flexible board. It is preferable that the second member to be connected is a resin film, a flexible printed board, a flexible flat cable, or a rigid flexible board. Resin films, flexible printed boards, flexible flat cables, and rigid flexible boards have properties of being highly flexible and relatively lightweight. When a conductive film is used to connect such members to be connected, solder particles tend to be less likely to gather on the electrodes. On the other hand, by using a conductive paste, even if a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible circuit board is used, by efficiently collecting solder particles on the electrodes, the reliability of the conduction between the electrodes can be improved. can fully enhance sexuality. When using a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible circuit board, compared to the case of using other connection target members such as semiconductor chips, the conduction reliability between electrodes is improved by not applying pressure. An improvement effect can be obtained more effectively.

The electrodes provided on the connection object members 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. When the electrode is an aluminum electrode, it may be an electrode made of only aluminum, or an electrode in which an aluminum layer is laminated on the surface of a metal oxide layer. Examples of materials 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 connection structure according to the present invention, it is preferable that the first electrode and the second electrode are arranged in an area array or a peripheral. The effects of the present invention are exhibited more effectively when the first electrode and the second electrode are arranged in an area array or peripheral arrangement. The area array is a structure in which electrodes are arranged in a grid pattern on the surface of the member to be connected where the electrodes are arranged. The peripheral means a structure in which electrodes are arranged on the outer periphery of the member to be connected. In the case of the structure in which the electrodes are arranged in a comb shape, the solder particles should be aggregated along the direction perpendicular to the comb, whereas in the area array or peripheral structure, the entire surface on which the electrodes are arranged It is necessary for the solder particles to aggregate uniformly. Therefore, in the conventional method, the amount of solder tends to be non-uniform, whereas in the method of the present invention, the solder particles can be uniformly aggregated over the entire surface.

EXAMPLES The present invention will be specifically described below 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
Thermosetting compound 2: Bisphenol A type epoxy compound, "YD-8125" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.
Thermosetting compound 3: Bisphenol F type epoxy compound, "YDF-8170C" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.
Thermosetting compound 4: Aliphatic epoxy compound, "Epolite 1600" manufactured by Kyoeisha Chemical Co., Ltd.

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

flux:
Flux 1: organic phosphonium salt, "PX-4MP" manufactured by Nippon Kagaku Kogyo Co., Ltd., melting point: 10°C
Flux 2: acidic phosphate compound (butyl acid phosphate), "JP-504" manufactured by Johoku Chemical Industry Co., Ltd., melting point: -13°C
Flux 3: "glutaric acid benzylamine salt", melting point 108°C
How to make Flux 3:
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 at room temperature until uniform. After that, 10.715 g of benzylamine (manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred for about 5 minutes to obtain a mixed liquid. The resulting mixture was placed in a refrigerator at 5-10° C. and allowed to stand overnight. Precipitated crystals were collected by filtration, washed with water, and dried under vacuum to obtain flux 3.

Flux 4: 4-hydroxymethylbenzoic acid, "4-hydroxymethylbenzoic acid" manufactured by Tokyo Chemical Industry Co., Ltd., melting point: 183°C

Solder particles:
Solder particles 1: SnBi solder particles, melting point 138° C., solder particles selected from "Sn42Bi58" manufactured by Mitsui Kinzoku, average particle size: 30 μm, specific gravity: 8.6
Solder particles 2: SnBi solder particles, melting point 138° C., solder particles selected from "Sn42Bi58" manufactured by Mitsui Kinzoku, average particle size: 10 μm, specific gravity: 8.6
Solder particles 3: SnBi solder particles, melting point 138° C., solder particles selected from "Sn42Bi58" manufactured by Mitsui Kinzoku, average particle diameter: 7 μm, specific gravity: 8.6
Solder particles 4: SnBi solder particles, melting point 138° C., solder particles selected from "Sn42Bi58" manufactured by Mitsui Kinzoku, average particle size: 5 μm, specific gravity: 8.6

Melting point of flux:
The melting point of the flux was determined by differential scanning calorimetry (DSC). As a differential scanning calorimetry (DSC) device, "EXSTAR DSC7020" manufactured by SII was used.

Specific gravity of solder particles:
The specific gravity of the solder particles was calculated using "Accupic II 1340" manufactured by Shimadzu Corporation.

( Reference Examples 1 to 8, Examples 9 to 16, Reference Examples 17 and 18 and Comparative Examples 1 to 3)
(1) Preparation of conductive material (anisotropic conductive paste) The components shown in Tables 1 and 2 below are blended in the amounts shown in Tables 1 and 2 below to obtain a conductive material (anisotropic conductive paste). rice field.

(2) Fabrication of connection structure As the first member to be connected, a glass epoxy substrate (material: FR- 4, thickness: 0.6 mm).

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

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

(evaluation)
(1) Sedimentation Velocity of Solder Particles The obtained conductive material was heated to 80° C. at a heating rate of 1° C./min, and the sedimentation velocity (SV80) of the solder particles when held at 80° C. was calculated. Also, the sedimentation velocity (SV25) of the solder particles at 25° C. of the obtained conductive material was calculated. The sedimentation velocity of the solder particles was calculated using "Stability Tester ST-1" manufactured by Eko Seiki Co., Ltd.

(2) Viscosity of conductive material The viscosity (η25) of the obtained conductive material at 25°C was measured using an E-type viscometer ("TVE22L" manufactured by Toki Sangyo Co., Ltd.) at 25°C and 5 rpm. .

In addition, the viscosity (η80) of the obtained conductive material at 80 ° C. was measured using a rheometer "HAAKE MARS III" manufactured by Thermo Fisher Scientific, with a frequency of 2 Hz, a heating rate of 0.11 ° C./sec, and a measurement temperature range of It was measured under the conditions of 40°C to 200°C. From the measurement results, the viscosity (η80) at 80°C was calculated.

(3) Arrangement Accuracy of Solder on Electrodes When the parts were viewed, the ratio X of the area where the solder part in the connecting part was arranged in 100% of the area of the facing part of the first electrode and the second electrode was evaluated. The placement accuracy of the solder on the electrodes was determined according to the following criteria.

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

(4) Continuity reliability (between upper and lower electrodes)
In the obtained 20 connected structures, the connection resistance per connection point between the upper and lower electrodes was measured by the four-probe method. An average value of connection resistance was calculated. From the relationship of voltage=current×resistance, the connection resistance can be obtained by measuring the voltage when a constant current flows. Conductivity reliability was determined according to the following criteria.

[Continuity Reliability Judgment Criteria]
○○○: The average connection resistance is 50 mΩ or less ○○: The average connection resistance is over 50 mΩ and 70 mΩ or less ○: The average connection resistance is over 70 mΩ and 100 mΩ or less ×: The average connection resistance is over 100 mΩ , or there is a connection failure

(5) Insulation reliability (between laterally adjacent electrodes)
The presence or absence of leakage between adjacent electrodes in the obtained 20 connection structures was evaluated by measuring the resistance value with a tester. Insulation reliability was evaluated according to the following criteria.

[Insulation Reliability Criteria]
○○○: The number of connection structures with a resistance value of 10 ⁸ Ω or more is 20 ○○: The number of connection structures with a resistance value of 10 ⁸ Ω or more is 18 or more and less than 20 ○: The resistance value is The number of connection structures with a resistance value of 10 ⁸ Ω or more is 15 or more and less than 18 Δ: The number of connection structures with a resistance value of 10 ⁸ Ω or more is 10 or more and less than 15 ×: The resistance value is 10 ⁸ Ω or more The number of connection structures is 5 or more and less than 10 XX: The number of connection structures with a resistance value of 10 ⁸ Ω or more is less than 5

The results are shown in Tables 1 and 2 below.

A similar tendency was observed when using a flexible printed circuit board, a resin film, a flexible flat cable, and a rigid flexible circuit board.

DESCRIPTION OF SYMBOLS 1, 1X... Connection structure 2... 1st connection object member 2a... 1st electrode 3... 2nd connection object member 3a... 2nd electrode 4, 4X... connection part 4A, 4XA... solder part 4B, 4XB ... Cured material part 11 ... Conductive material 11A ... Solder particles 11B ... Thermosetting component

Claims (8)

A conductive material comprising a thermosetting component, a plurality of solder particles, and a flux;
The average particle size of the solder particles is less than 10 μm,
A conductive material, wherein the sedimentation speed of the solder particles when the conductive material is heated to 80°C at a temperature increase rate of 1°C/min and held at 80°C is 0.2 µm/s or more. 2. The conductive material according to claim 1, wherein the sedimentation velocity of the solder particles of the conductive material at 25[deg.] C. is 0.02 [mu]m/s or less. 3. The conductive material according to claim 1, wherein said flux has a melting point of 80[deg.] C. or less. The conductive material according to any one of claims 1 to 3 , wherein the solder particles have a specific gravity of 6 or more. The conductive material has a viscosity at 25° C. of 50 Pa s or more,
The conductive material according to any one of claims 1 to 4 , wherein the conductive material has a viscosity at 80°C of 10 Pa·s or less. The conductive material according to any one of claims 1 to 5 , which is a conductive paste. a first connection target member having a first electrode on its surface;
a second connection target member having a second electrode on its surface;
A connecting portion that connects the first connection target member and the second connection target member,
The material of the connection portion is the conductive material according to any one of claims 1 to 6 ,
A connection structure, wherein the first electrode and the second electrode are electrically connected by a solder portion in the connection portion. Using the conductive material according to any one of claims 1 to 6 , disposing the conductive material on the surface of a first connection target member having a first electrode on the surface;
A second member to be connected having a second electrode on the surface of the conductive material opposite to the side of the first member to be connected is provided so that the first electrode and the second electrode face each other. arranging to
By heating the conductive material to a melting point of the solder particles or higher, a connecting portion connecting the first member to be connected and the second member to be connected is formed from the conductive material, and A method of manufacturing a connection structure, comprising the step of electrically connecting the first electrode and the second electrode with a solder portion in the connection portion.

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