JP7280758B2 - 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.

Solder pastes containing relatively large amounts of solder are known.

Also, anisotropic conductive materials are widely known that contain a relatively large amount of binder resin compared to solder paste. Examples of the anisotropic conductive material include an anisotropic conductive paste and an anisotropic conductive film. In the anisotropic conductive material, conductive particles are dispersed in a binder resin.

The anisotropic conductive material is used to obtain various connection structures. Examples of the connection 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 electrodes of a flexible printed circuit board and electrodes 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.

Patent Document 1 below discloses a conductive material containing a first curable compound, a curing agent, and solder particles, wherein the conductive material does not contain or contains a second curable compound. disclosed. In this conductive material, the absolute value of the difference between the SP value of the first curable compound and the SP value of the curing agent is 2 or more, and the SP value of the second curable compound and the SP value of the curing agent The absolute value of the difference between the values is less than 2, and the content of the first curable compound is 5% by weight in the total 100% by weight of the first curable compound and the second curable compound. That's it. In the volume-based particle size distribution of the solder particles, d90 of the solder particles is 10 μm or less.

JP 2018-195525 A

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 solder particles are preferably placed 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 by printing such as screen printing, and then heated by reflow or the like. 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 recent years, along with the miniaturization of electronic devices, the size of the components mounted on the electronic devices has also been reduced. However, reducing the particle size of the solder particles tends to increase the viscosity of the conductive material. Therefore, when solder particles having a small particle diameter are used, it may be difficult to maintain the shape of the conductive material after printing, and printing unevenness may occur. Moreover, even when solder particles having a large particle size are used, it may be difficult to maintain the shape of the conductive material after printing, and printing unevenness may occur. If the shape of the conductive material after printing cannot be maintained and printing unevenness occurs, the conductive material may move away from the place where it is originally arranged (for example, the vicinity of the electrode, etc.). As a result, the solder particles contained in the conductive material are arranged in areas where 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 The reliability of conduction between electrodes may be lowered, and the reliability of insulation between adjacent lateral electrodes may be lowered.

SUMMARY OF THE INVENTION An object of the present invention is to provide a conductive material capable of suppressing the occurrence of unevenness during placement of the conductive material. 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 and a plurality of solder particles, and in the volume-based particle size distribution of the solder particles, at least one There is provided a conductive material in which there are 30% or more of the integrated values of all the peaks present in a region having a particle diameter of 1 μm or less, out of 100% of the integrated values of the entire particle size distribution. be.

In a specific aspect of the conductive material according to the present invention, there are two or more peaks in the volume-based particle size distribution of the solder particles, and all the peaks present in the volume-based particle size distribution of the solder particles. Among them, when the peak with the highest peak height is set as the first peak and the peak with the second highest peak height is set as the second peak, the peak height of the first peak is the second peak height. The ratio of the peak to the peak height is 1 or more and 5 or less.

In a specific aspect of the conductive material according to the present invention, the ratio of the integrated value of the first peak to the integrated value of the second peak is 1 or more and 5 or less.

In a specific aspect of the conductive material according to the present invention, the first peak is a peak present in a region with a particle diameter of 1 μm or less, and the second peak is a region with a particle diameter exceeding 1 μm. or the first peak is present in a region where the particle size exceeds 1 μm, and the second peak is present in a region where the particle size is 1 μm or less peak.

In a specific aspect of the conductive material according to the present invention, the first peak is a peak present in a region with a particle diameter of 1 μm or less, and the second peak is a region with a particle diameter exceeding 1 μm. is the peak present in

In a specific aspect of the conductive material according to the present invention, in the volume-based particle size distribution of the solder particles, D50 of the solder particles is 10 nm or more and 3 μm or less.

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

In a specific aspect of the conductive material according to the present invention, the conductive material contains flux.

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 and a plurality of solder particles. In the conductive material according to the present invention, in the volume-based particle size distribution of the solder particles, at least one peak exists in a region where the particle size is 1 μm or less, and the total integrated value of the particle size distribution is 100%. The ratio of the integrated value of all peaks present in the region with a particle diameter of 1 μm or less is 30% or more. Since the conductive material according to the present invention has the above configuration, it is possible to suppress the occurrence of unevenness during placement of the conductive material.

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 and a plurality of solder particles. In the conductive material according to the present invention, in the volume-based particle size distribution of the solder particles, at least one peak exists in a region where the particle size is 1 μm or less, and the total integrated value of the particle size distribution is 100%. The ratio of the integrated value of all peaks present in the region with a particle diameter of 1 μm or less is 30% or more. That is, in the conductive material according to the present invention, the volume-based particle size distribution of the solder particles has at least one peak in a region where the particle size is 1 μm or less, and the integrated value of the entire particle size distribution is 100. %, the ratio of the integrated value of all peaks existing in a region with a particle diameter of 1 μm or less is 30% or more.

Since the conductive material according to the present invention has the above configuration, it is possible to suppress the occurrence of unevenness during placement of the conductive material. In particular, with the conductive material according to the present invention, it is possible to suppress the occurrence of uneven printing of the conductive material by screen printing or the like. In the conductive material according to the present invention, the shape of the conductive material after printing is well maintained. Therefore, in the conductive material according to the present invention, the solder can be efficiently arranged on the electrodes, and as a result, the reliability of conduction between the upper and lower electrodes to be connected can be improved. Insulation reliability between the electrodes in the direction can be enhanced.

A conventional conductive material that simply contains solder particles with a small particle size tends to cause unevenness in placement of the conductive material. The inventors have found a configuration capable of suppressing the occurrence of unevenness in arranging the conductive material even when solder particles having a small particle size are used. The present inventors have found that by adjusting the particle size distribution of solder particles, it is possible to suppress the occurrence of unevenness during placement of the conductive material even when solder particles having a small particle size are used.

In the present invention, since solder particles having a small particle size and a specific particle size distribution are used, it is possible to suppress the occurrence of unevenness during placement of the conductive material. With the conductive material according to the present invention, even when the solder particles have a small particle size, it is possible to suppress the occurrence of unevenness during placement of the conductive material. Therefore, in the conductive material according to the present invention, even when the particle diameter of the solder particles is small, the solder can be efficiently arranged on the electrodes, and as a result, the conduction between the upper and lower electrodes to be connected is improved. Reliability can be improved, and insulation reliability between adjacent lateral electrodes can be improved.

Moreover, since the conductive material according to the present invention has the above configuration, it is possible to suppress the generation of voids during bonding.

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).

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

From the viewpoint of arranging the solder on the electrode more efficiently, the viscosity (η25) of the conductive material at 25° C. immediately after production is preferably 100 Pa·s or more, more preferably 120 Pa·s or more, and still more preferably is 140 Pa·s or more, preferably 200 Pa·s or less, more preferably 180 Pa·s or less. The viscosity (η25) can be appropriately adjusted depending on the types and amounts of ingredients to be blended.

As the viscosity (η25), the viscosity (ηA) of the conductive material at 25°C immediately after thawing the conductive material that has been stored frozen immediately after production and reaching 25°C may be used.

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

In this specification, the conditions for the frozen storage of the conductive material for measuring the viscosity are the conditions for storage at −40° C. for 7 days. On the other hand, there is no particular limitation on the above-mentioned frozen storage conditions when the conductive material is actually used. The temperature of the above frozen storage at the time of actual use of the conductive material is not particularly limited, and may be less than 0°C. The temperature of the above frozen storage during actual use of the conductive material may be −10° C. or lower, −20° C. or lower, or −40° C. or lower. The period of the above frozen storage when the conductive material is actually used is not particularly limited, and may be 180 days or less. The period of frozen storage may be 30 days or longer, 60 days or longer, 90 days or longer, or 120 days or longer.

Moreover, in this specification, the thawing condition of the conductive material for measuring the viscosity is the condition of storage at 25°C. On the other hand, there is no particular limitation on the method of thawing the above-mentioned electrically conductive material that has been stored frozen when the electrically conductive material is actually used. Examples of the method for thawing the above-mentioned conductive material that has been frozen and stored at the time of actual use of the conductive material include a method of thawing under room temperature conditions, a method of thawing under refrigeration conditions, and a method of thawing under heating conditions. . The room temperature condition is preferably 20° C. or higher and 25° C. or lower. The refrigeration conditions are preferably above 0°C and 10°C or less. The heating conditions are preferably 30° C. or higher and 35° C. or lower.

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 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.

The conductive material is preferably used after being printed, more preferably after being screen-printed.

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)
The conductive material includes 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 made 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 low.

In the conductive material according to the present invention, in the volume-based particle size distribution of the solder particles, at least one peak exists in a region where the particle size is 1 μm or less, and the total integrated value of the particle size distribution is 100%. The ratio of the integrated values of all peaks present in the region with a particle diameter of 1 μm or less (percentage of the total integrated values) is 30% or more. In the present invention, since the specific solder particles are used, it is possible to suppress the occurrence of unevenness during placement of the conductive material.

In the volume-based particle size distribution of the solder particles, the number of peaks present in a region having a particle diameter of 1 μm or less is at least one. In the volume-based particle size distribution of the solder particles, the number of peaks present in a region having a particle diameter of 1 μm or less may be 1, 2, or 2 or more. good too.

In the volume-based particle size distribution of the solder particles, the ratio of the integrated values of all the peaks existing in the region with a particle diameter of 1 μm or less in 100% of the integrated value of the entire particle size distribution (percentage of the total integrated value ) is preferably 40% or more, more preferably 50% or more. When the ratio is equal to or higher than the lower limit, it is possible to more effectively suppress the occurrence of unevenness during placement of the conductive material.

The volume-based particle size distribution of the solder particles may or may not have two or more peaks. When there is only one peak in the volume-based particle size distribution of the solder particles, the peak exists in a region where the particle diameter is 1 μm or less. In the volume-based particle size distribution of the solder particles, when two or more peaks are present, such peaks may all be present in a region where the particle size is 1 μm or less, and the particle size is 1 μm or less. A peak may exist in both the region where the particle diameter is greater than 1 μm.

The peak present in the region with a particle size of 1 μm or less means a peak with a particle size of 1 μm or less at the peak top. A peak existing in a region with a particle size exceeding 1 μm means a peak with a particle size exceeding 1 μm at the peak top.

When there are two or more peaks in the volume-based particle size distribution of the solder particles, the peak having the highest peak height among all the peaks present in the volume-based particle size distribution of the solder particles is selected as the first peak. and the peak with the second highest peak height is taken as the second peak.

The ratio of the peak height of the first peak to the peak height of the second peak (peak height of the first peak/peak height of the second peak) is preferably 1 or more, preferably 5 or less. When the ratio (peak height of the first peak/peak height of the second peak) is equal to or greater than the lower limit and equal to or less than the upper limit, the occurrence of unevenness during placement of the conductive material can be more effectively suppressed. can be done.

The ratio of the integrated value of the first peak to the integrated value of the second peak (integrated value of the first peak/integrated value of the second peak) is preferably 1 or more and preferably 5 or less. . When the ratio (integrated value of the first peak/integrated value of the second peak) is equal to or greater than the lower limit and equal to or less than the upper limit, it is possible to more effectively suppress the occurrence of unevenness during placement of the conductive material. .

The first peak may be a peak present in a region with a particle size of 1 μm or less, or may be a peak present in a region with a particle size of more than 1 μm. The second peak may be a peak present in a region with a particle size of 1 μm or less, or may be a peak present in a region with a particle size of more than 1 μm.

From the viewpoint of more effectively suppressing the occurrence of unevenness during placement of the conductive material, the first peak and the second peak should satisfy the following (1) or the following (2). Preferably, it is more preferable to satisfy the following (1). (1) The first peak is present in a region with a particle size of 1 μm or less, and the second peak is present in a region with a particle size of more than 1 μm. (2) The first peak is present in a region with a particle size exceeding 1 μm, and the second peak is a peak present in a region with a particle size of 1 μm or less.

In the volume-based particle size distribution of the solder particles, D50 of the solder particles is preferably 3 μm or less, more preferably 1 μm or less. D50 of the solder particles is preferably 10 nm or more. When the D50 of the solder particles is equal to or higher than the lower limit, the effects of the present invention can be exhibited more effectively.

The D50 of the solder particles is the particle diameter of the solder particles when the cumulative volume of the solder particles is 50%. The D50 of the solder particles can be calculated from the volume-based particle size distribution.

The volume-based particle size distribution of the solder particles is determined using a laser diffraction particle size distribution analyzer. Examples of the laser diffraction particle size distribution analyzer include "Mastersizer 3000" manufactured by Malvern.

In addition, the integrated value of the peak is obtained by accumulating the volume value at each particle size in the volume-based particle size distribution.

Examples of the method for adjusting the particle size distribution of the solder particles to the preferred aspect include a sieving method using a sieve or the like and a method of pulverizing the solder particles using a jet mill or the like.

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. From the viewpoint of suppressing thermal deterioration during fabrication of the bonded structure, the melting point of the low-melting-point metal is preferably 400° C. or lower, more preferably 350° C. or lower, and even more preferably 300° C. or lower. The solder particles are preferably low-melting solder having a melting point of less than 250.degree.

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

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, the connection reliability between the solder portion and the electrode is further enhanced.

The tin content is measured 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 do.

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, and tin-indium alloys. 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.

From the viewpoint of exhibiting the effects of the present invention more effectively, the solder particles preferably contain tin and silver, or contain tin and copper, and more preferably contain tin, silver, and copper. more preferred.

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 in 100% by weight of the metal contained in the solder particles. It is preferably 1% by weight or less.

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.

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, and particularly preferably 55% by weight or more. is 90% by weight or less, more preferably 85% by weight or less, and still more preferably 80% by weight or less. When the content of the solder particles is equal to or more than the lower limit and equal to or less than the upper limit, the solder can be arranged more efficiently on the electrodes, and it is easy to arrange a large amount of solder between the electrodes, resulting in reliability of conduction. It is possible to enhance the property more effectively. 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. 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 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. As for the said thermosetting compound, only 1 type may be used and 2 or more types may be used together.

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

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 novolak 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 target It is possible to suppress misalignment with the member. Furthermore, the heat during curing can greatly reduce the viscosity of the conductive material, and the cohesion of the solder during conductive connection can be efficiently advanced.

From the viewpoint of arranging the solder 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.

From the viewpoint of more efficiently arranging the solder on the electrode, from the viewpoint of more effectively increasing the reliability of conduction between the upper and lower electrodes to be connected, and from the viewpoint of more effectively suppressing the discoloration of the thermosetting compound. From the viewpoint, the thermosetting compound preferably has high heat resistance, and is more preferably a novolac epoxy compound. Novolac 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, still more preferably 10% by weight or more, and preferably 99% by weight or less. It is more preferably 90% by weight or less, still more preferably 80% by weight or less, and particularly preferably 70% by weight or less. When the content of the thermosetting compound is the lower limit or more and the upper limit or less, the solder 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 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 5% by weight or more, more preferably 8% by weight or more, still more preferably 10% by weight or more, and more preferably 99% by weight or less. is 90% by weight or less, more preferably 80% by weight or less, and 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 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 continuity. From the viewpoint of further increasing the impact resistance, the content of the epoxy compound is preferably large.

(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 thermosetting agent is not particularly limited. Examples of the heat curing agent include imidazole curing agents, phenol curing agents, thiol curing agents, amine curing agents, acid anhydride curing agents, thermal cationic curing agents and thermal radical generators. 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 thermosetting agent is equal to or higher than the lower limit and equal to or lower than the upper limit, the solder is arranged on the electrode more efficiently. From the viewpoint of more efficiently arranging the solder on the electrodes and from the viewpoint of more effectively increasing the reliability of conduction between the upper and lower electrodes to be connected, the reaction initiation temperature of the thermosetting agent is 80°C. Above, it is especially preferable that it is 140 degrees C or less.

The reaction start temperature of the thermosetting agent means the temperature at which the exothermic peak starts to rise in DSC. Examples of the DSC apparatus include "EXSTAR DSC7020" manufactured by SII.

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 lower limit, it is easy to sufficiently cure the conductive material. If 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.

(Thermosetting component: curing accelerator)
The conductive material may contain a curing accelerator. The 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. Only one kind of the curing accelerator may be used, or two or more kinds thereof may be used in combination.

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 accelerator includes imidazole compounds, isocyanurates of imidazole compounds, dicyandiamide, dicyandiamide derivatives, melamine compounds, melamine compound derivatives, 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 and methyldiphenylphosphine, etc. organic phosphorus compounds and the like.

The phosphonium salt is not particularly limited. Examples of the phosphonium salts include tetra-butylphosphonium bromide, tetra-butylphosphonium O—O diethyldithiophosphate, methyltributylphosphonium dimethylphosphate, tetra-butylphosphonium benzotriazole, tetra-butylphosphonium tetrafluoroborate, and tetra-butyl phosphonium tetraphenylborate and the like.

The content of the curing accelerator is appropriately selected so that the thermosetting compound cures satisfactorily. The content of the curing accelerator with respect 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, preferably 10 parts by weight or less, more preferably 8 parts by weight. Part by weight or less. When the content of the curing accelerator is equal to or more than the lower limit and equal to or less than the upper limit, the thermosetting compound can be cured satisfactorily. Further, when the content of the curing accelerator is not less than the above lower limit and not more than the above upper limit, the solder can be arranged on the electrodes more efficiently, and the conduction reliability between the upper and lower electrodes to be connected can be improved. can be enhanced more effectively.

(flux)
The conductive material preferably contains flux. By using flux, the solder can be more efficiently placed on the electrodes. The above flux is not particularly limited. Flux generally used for soldering or the like can be used as the flux.

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. The use of this preferable flux further enhances the reliability of electrical connection between the electrodes.

The active temperature (melting point) of the flux is preferably 50° C. or higher, more preferably 70° C. or higher, still more preferably 80° C. or higher, preferably 200° C. or lower, more preferably 190° C. or lower, and even more preferably 160° C. °C or less, more preferably 150°C or less, and even more preferably 140°C or less. When the activation temperature of the flux is equal to or higher than the lower limit and equal to or lower than the upper limit, the flux effect is exhibited more effectively, and the solder can be arranged on the electrode 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.

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

From the viewpoint of arranging the solder on the electrode more efficiently, the melting point of the flux is preferably higher than the reaction initiation temperature of the thermosetting agent, more preferably 5° C. or higher, and 10° C. or higher. Higher is more preferred.

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

The flux is preferably a flux that releases cations when heated. The use of a flux that releases cations upon heating allows for much more efficient placement of the solder on the electrodes.

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

From the viewpoints of more efficiently arranging the solder on the electrode, more effectively improving the insulation reliability, and more effectively improving the conduction reliability, the above-mentioned flux contains an acid compound and a base compound. It is preferably a salt with.

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 viewpoints of more efficiently arranging the solder on the electrode, more effectively improving the insulation reliability, and more effectively improving the conduction reliability, the above acid compounds include glutaric acid, cyclohexyl Carboxylic acid or adipic acid is 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 viewpoint of more efficiently arranging solder on the electrode, more effectively improving insulation reliability, and more effectively improving conduction reliability, the base compound is benzylamine. is preferred.

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. If the content of the flux is above the lower limit and below the upper limit, it becomes even more difficult to form an oxide film on the surface of the solder and the electrode, and the oxide film formed on the surface of the solder and the electrode is further effectively removed. can be effectively removed.

(filler)
The conductive material may contain a filler. The filler may be an organic filler or an inorganic filler. By including the filler in the conductive material, the solder can be more uniformly agglomerated on all the electrodes of the substrate. In addition, since the conductive material contains a filler, the solder particles can be more uniformly dispersed in the conductive material.

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.

In 100% by weight of the conductive material, the content of the filler 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. is. 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 is 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 a specific conductive material is used, solder particles tend to gather between the first electrode and the second electrode, and the solder is applied to the electrodes (line ) can be efficiently placed on the Also, part of the solder is less likely to be placed in the regions (spaces) where the electrodes are not formed, and the amount of solder placed in the regions where the electrodes are not formed can be considerably 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.

Also, in order to place the solder on the electrodes more efficiently and to significantly reduce the amount of solder placed in the areas where the electrodes are not formed, the conductive material is a conductive paste rather than a conductive film. 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, it is difficult for some of the plurality of solder particles to be arranged in the regions (spaces) where the electrodes are not formed, and the amount of solder arranged in the regions where the electrodes are not formed can be further reduced. 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 particles as compared with 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, a plurality of 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 component 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 connection portion 4, solder does not exist 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. In a region different from the solder portion 4A (hardened material portion 4B portion), there is no solder separate from the solder portion 4A. As long as the amount is small, the solder may exist 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. In addition, it is preferable that the solder wets and spreads on the surfaces of the electrodes, and the solder does not necessarily have to be collected between the upper and lower electrodes.

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 the solder particles, the solder portion 4A and the first electrode 2a, and the solder portion 4A and the second electrode 2a, compared to the case of using the conductive particles whose outer surface is a metal such as nickel, gold, or copper. 2, the contact area with the electrode 3a becomes large. This also increases the conduction reliability and connection reliability in the connection structure 1 . 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 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 portion 4XA protruding laterally from the regions where the first and second electrodes 2a and 3a face each other is a part of the solder portion 4XA and is not solder separate from the solder portion 4XA. In this embodiment, the amount of solder separated from the solder portion can be reduced, but the solder 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 connection 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 connection 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 connection portion, and the second electrode, the first electrode and the second electrode More preferably, the solder portion in the connection 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 connection 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 connection 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, a plurality of solder particles 11A, and flux is placed on the surface of the first member 2 to be connected ( first step). The conductive material 11 used contains a thermosetting compound and a thermosetting agent as the thermosetting component 11B. In this embodiment, the conductive material 11 is a conductive paste.

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 conductive material may be arranged only on the surface of the first electrode.

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, it is possible to effectively suppress the occurrence of bleeding of the conductive material, blurring of the conductive material, and the like even if screen printing is performed repeatedly. In addition, since the specific conductive material 11 is used in the present embodiment, the shape of the conductive material after printing can be maintained, and the occurrence of unevenness during placement of the conductive material can be reduced. 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. The conductive material according to the present invention can also be used by methods other than printing, such as screen printing.

In the second step and the third step, it is preferable not to pressurize. 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 target member 2 and the second connection target member 2 are connected with the first electrode 2a and the second electrode 3a slightly misaligned. Even when the member 3 is overlaid, the first electrode 2a and the second electrode 3a can be connected by correcting a slight deviation (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.

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 230° C. or higher, more preferably 250° C. or higher, and preferably 450° C. or lower, more preferably 350° C. or lower, and still more preferably 300° C. or lower.

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

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. 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. In the case where the first electrodes and the second electrodes are arranged in an area array or peripheral arrangement, the solder can be more effectively agglomerated on the electrodes. 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 is 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 should be aggregated along the direction perpendicular to the comb. The solder should agglomerate 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 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 novolac type epoxy compound, "DEN431" manufactured by DOW
Thermosetting compound 2: Bisphenol A type epoxy compound, "DER354" manufactured by DOW

Thermosetting component (curing accelerator):
Curing accelerator 1: "BF3-MEA" manufactured by Tokyo Chemical Industry Co., Ltd., boron trifluoride-monoethylamine complex

Solder particles:
Solder particles 1 to 5 below were obtained by screening the solder particles with a sieve.

Solder particles 1: Sn96.5Ag3Cu0.5 solder particles, average particle size 100 nm
Solder particles 2: Sn96.5Ag3Cu0.5 solder particles, average particle size 2 μm
Solder particles 3: Sn96.5Ag3Cu0.5 solder particles, average particle size 3 μm
Solder particles 4: Sn96.5Ag3Cu0.5 solder particles, average particle size 10 μm
Solder particles 5: Sn96.5Ag3Cu0.5 solder particles, average particle size 30 μm

flux:
Flux 1: "glutaric acid benzylamine salt", melting point 108°C
How to make Flux 1:
45 g of water, 75 g of ethanol, and 13.89 g of adipic acid (manufactured by Wako Pure Chemical Industries, Ltd.), which are reaction solvents, 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°C to 10°C and allowed to stand overnight. Precipitated crystals were separated by filtration, washed with water, and dried in a vacuum to obtain a flux 1.

(Examples 1 and 2 and Comparative Examples 1 to 3)
(1) Preparation of Conductive Material (Anisotropic Conductive Paste) The components shown in Table 1 below were blended in the amounts shown in Table 1 below to obtain a conductive material (anisotropic conductive paste).

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

As a second member to be connected, a flexible printed circuit board (made of polyimide, thickness 0.1 mm) having a copper electrode pattern (L/S: 50 μm/50 μm, electrode length: 3 mm, electrode thickness: 12 μm) on the lower surface. prepared.

A conductive material (anisotropic conductive paste) immediately after production was printed on the upper surface of the glass epoxy substrate by screen printing 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, after 15 seconds from 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) Particle Size Distribution of Solder Particles Volume-based particle size distribution of solder particles was measured using a laser diffraction particle size distribution analyzer ("Mastersizer 3000" manufactured by Malvern). As for the analysis method, the particle shape was spherical, the particle density was 7.4 g/cm ³ , and the light intensity distribution pattern was determined. From the obtained particle size distribution results, the following was obtained. In addition, when only one peak is observed in the particle size distribution, the first peak means this peak. When two or more peaks are observed in the particle size distribution, the first peak means the peak with the highest peak height among all existing peaks, and the second peak means all existing peaks. It means the peak with the second highest peak height among the peaks.

Number of peaks present in a region with a particle diameter of 1 μm or less Percentage of integrated values of all peaks present in a region with a particle diameter of 1 μm or less in 100% of the integrated value of the entire particle size distribution D50 of solder particles
Particle size of first peak (particle size of peak top)
Second peak particle size (peak top particle size)
Integrated value of first peak Integrated value of second peak Ratio (integrated value of first peak/integrated value of second peak)
Ratio (peak height of first peak/peak height of second peak)

According to the following criteria, the ratio of the integrated values of all peaks present in the region where the particle diameter is 1 μm or less in 100% of the overall integrated value of the particle size distribution, D50, the ratio (integrated value of the first peak / second ) and the ratio (peak height of the first peak/peak height of the second peak) were evaluated.

[Criteria for determination of percentage of integrated values of all peaks present in regions with particle diameters of 1 μm or less in 100% of integrated values of overall particle size distribution]
○○: 50% or more ○: 30% or more and less than 50% ×: less than 30%

[Determination Criteria for D50 of Solder Particles]
○○: 10 nm or more and 1 μm or less ○: More than 1 μm and 3 μm or less ×: More than 3 μm

[Ratio (integral value of first peak/integral value of second peak)]
○○: 1 or more and 5 or less ×: more than 5

[Ratio (peak height of first peak/peak height of second peak)]
○○: 1 or more and 5 or less ×: more than 5

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

[Criteria for Viscosity (η25)]
○○: 120 Pa s or more and 180 Pa s or less ○: 100 Pa s or more and less than 120 Pa s, or more than 180 Pa s and 200 Pa s or less ×: less than 100 Pa s, or more than 200 Pa s

(3) TI
The viscosity (η25) at 25° C. and 5 rpm immediately after preparation of the obtained conductive material (anisotropic conductive paste) and the viscosity at 25° C. and 0.5 rpm were measured using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd. “TVE22L ”), and TI was calculated from the following formula.

TI = (viscosity at 25°C, 0.5 rpm)/(viscosity at 25°C, 5 rpm)

(4) Print unevenness (shape of conductive material after printing)
The obtained conductive material was printed on a slide glass using an applicator having a thickness of 50 μm. The surface roughness at that time was observed with a microscope, and printing unevenness (the shape of the conductive material after printing) was determined according to the following criteria.

[Criteria for judgment of uneven printing (shape of conductive material after printing)]
○○: The absolute value of the difference between the maximum and minimum values of surface roughness is less than 1 μm ○: The absolute value of the difference between the maximum and minimum values of surface roughness is 1 μm or more and less than 3 μm △: Maximum surface roughness The absolute value of the difference between the value and the minimum value is 3 μm or more and less than 20 μm ×: The absolute value of the difference between the maximum value and the minimum value of the surface roughness is 20 μm or more and less than 50 μm XX: The maximum value and the minimum value of the surface roughness The absolute value of the difference is 50 μm or more

(5) Arrangement Accuracy of Solder on Electrode In the obtained connection structure, 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 ratio X of the area where the solder portion in the connection portion is arranged in 100% of the area of the portion where the first electrode and the second electrode face each other 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%

(6) Insulation reliability (between laterally adjacent electrodes)
Twenty connected structures were produced in the same manner as described above. In the connection structure, the presence or absence of leakage between adjacent electrodes 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 18 or more ○: The number of connection 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 connection structures with a resistance value of ⁸ Ω or more is more than 5 and less than 10 XX: The number of connection structures with a resistance value of 10 ⁸ Ω or more is 5 or less

Details and results are shown in Table 1 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 (11)

A conductive material comprising a thermosetting component and a plurality of solder particles;
In the volume-based particle size distribution of the solder particles, two or more peaks are present, and the peaks are present in both a region with a particle size of 1 μm or less and a region with a particle size of more than 1 μm , and the particle size distribution A conductive material, wherein the ratio of integrated values of all peaks present in a region having a particle diameter of 1 μm or less is 30% or more in 100% of the total integrated value. In the volume-based particle size distribution of the solder particles, among all the peaks present in the volume-based particle size distribution of the solder particles, the highest peak is defined as a first peak, and the peak height is When the second highest peak is the second peak,
2. The conductive material according to claim 1, wherein the ratio of the peak height of said first peak to the peak height of said second peak is 1 or more and 5 or less. 3. The conductive material according to claim 2, wherein the ratio of the integrated value of said first peak to the integrated value of said second peak is 1 or more and 5 or less. The first peak is a peak present in a region with a particle diameter of 1 μm or less, and the second peak is a peak present in a region with a particle diameter exceeding 1 μm, or the first 4. The conductive according to claim 2 or 3, wherein the peak of is a peak present in a region with a particle size exceeding 1 μm, and the second peak is a peak present in a region with a particle size of 1 μm or less material. The first peak is a peak present in a region with a particle size of 1 μm or less, and the second peak is a peak present in a region with a particle size exceeding 1 μm, according to claim 4. conductive material. The conductive material according to any one of claims 1 to 5, wherein in the volume-based particle size distribution of the solder particles, the D50 of the solder particles is 10 nm or more and 3 µm or less. The conductive material of any one of claims 1-6, wherein the thermosetting component comprises an epoxy compound. Conductive material according to any one of claims 1 to 7, comprising a flux. The conductive material according to any one of claims 1 to 8, 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 9,
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 9, placing 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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