TW201625760A - Electroconductive paste, connection structure, and method for manufacturing connection structure - Google Patents

Abstract

Provided is an electroconductive paste with which it is possible to control with high precision gaps between electrodes, and with which it is further possible to efficiently dispose solder particles on the electrodes, and to increase conduction reliability between electrodes. The electroconductive paste according to the present invention is used for connecting a first member to be connected having a first electrode on the surface thereof and a second member to be connected having a second electrode on the surface thereof, and electrically connecting the first electrode and the second electrode. The electroconductive paste includes a thermosetting component, a plurality of solder particles, and a plurality of spacers having a melting point of 250 DEG C or higher, the average particle diameter of the spacers being greater than the average particle diameter of the solder particles.

Description

Conductive paste, connection structure, and manufacturing method of connection structure

The present invention relates to a conductive paste comprising solder particles. Moreover, the present invention relates to a connection structure using the above-described conductive paste and a method of manufacturing the connection structure.

Anisotropic conductive materials such as an anisotropic conductive paste and an anisotropic conductive film are widely known. In the above anisotropic conductive material, conductive particles are dispersed in the binder resin.

In order to obtain various connection structures, the anisotropic conductive material is used, for example, for connection between a flexible printed substrate and a glass substrate (FOG (Film on Glass)), and connection between a semiconductor wafer and a flexible printed substrate (COF (Chip on) Film, film flip chip), connection of semiconductor wafer to glass substrate (COG (Chip on Glass)), and connection between flexible printed substrate and epoxy glass substrate (FOB (Film on Board)) Wait.

When the electrode of the flexible printed circuit board is electrically connected to the electrode of the epoxy glass substrate by the anisotropic conductive material, an anisotropic conductive material containing conductive particles is disposed on the epoxy glass substrate. Next, a flexible printed circuit board is laminated to perform heating and pressurization. Thereby, the anisotropic conductive material is cured, and the electrodes are electrically connected to each other via the conductive particles to obtain a bonded structure.

As an example of the above-mentioned anisotropic conductive material, Patent Document 1 discloses a resin layer containing a thermosetting resin, a solder powder, and a curing agent, and the solder powder and the curing agent are present in the resin layer. Then bring it. This adhesive tape is in the form of a film and is not in the form of a paste.

Further, Patent Document 1 discloses a method of using the above-described subsequent tape. Specifically, the first substrate, the subsequent tape, the second substrate, the adhesive tape, and the third substrate are sequentially laminated from the bottom to the top to obtain a laminate. At this time, the first electrode provided on the surface of the first substrate faces the second electrode provided on the surface of the second substrate. Further, the second electrode provided on the surface of the second substrate faces the third electrode provided on the surface of the third substrate. Then, the laminate is heated at a specific temperature to proceed. Thereby, the connection structure is obtained.

In the following Patent Document 2, it is disclosed that the first electrode that is the electrode of the connection portion of the first electronic component and the second electrode that is the electrode of the connection portion of the second electronic component are electrically connected to each other. Follow-up agent. The anisotropic conductive adhesive includes an insulating polymer resin, bonded particles, and spacer particles. The bonded particles are melted by heat generated by ultrasonic waves applied to the anisotropic conductive adhesive. The spacer particles have a higher melting point than the bonded particles. Examples of the above-mentioned joined particles include solder particles.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] WO2008/023452A1

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2012-532979

The adhesive tape described in Patent Document 1 has a film shape and is not a paste. Therefore, it is difficult to efficiently dispose the solder powder on the electrodes (lines). For example, in the adhesive tape described in Patent Document 1, it is also easy to arrange one of the solder powders in a region (gap) in which the electrode is not formed. The solder powder disposed in the region where the electrode is not formed does not contribute to the conduction between the electrodes.

Further, even in the case of an anisotropic conductive paste containing solder powder, the solder powder may be disposed on the electrode (wire) inefficiently. Further, in the case of using an anisotropic conductive paste containing solder powder, the interval between the electrodes is likely to be uneven after the conductive connection. also, In the case of the adhesive described in Patent Document 2, the bonded particles such as solder particles are not efficiently disposed on the electrode (wire). In addition, as described in Patent Document 2, in addition to the bonding particles such as solder particles, spacer particles are additionally used, and the bonding particles may not be efficiently disposed on the electrodes (lines).

An object of the present invention is to provide a conductive paste which can accurately control the interval between electrodes and can efficiently dispose solder particles on an electrode to improve the conduction reliability between electrodes. Moreover, the present invention provides a connection structure using the above-described conductive paste and a method of manufacturing the connection structure.

According to a broader aspect of the present invention, there is provided a conductive paste for connecting a first connection member having a first electrode on a surface thereof and a second connection member having a second electrode on a surface thereof to connect the first electrode The second electrode is electrically connected to the second electrode, and includes: a thermosetting component, a plurality of solder particles, and a plurality of spacers having a melting point of 250 ° C or higher, and an average particle diameter of the spacer is larger than an average particle of the solder particles path.

In a specific aspect of the conductive paste of the present invention, the spacer is an insulating particle.

In a specific aspect of the conductive paste of the present invention, the conductive paste is used to contact the spacer between the first connection target member and the second connection target member.

In a specific aspect of the conductive paste of the present invention, the conductive paste is heated to a temperature higher than a melting point of the solder particles and a hardening temperature of the thermosetting component when the first electrode and the second electrode are electrically connected to each other. As described above, a plurality of the above-described solder particles are aggregated and integrated for use.

In a specific aspect of the conductive paste of the present invention, the ratio of the average particle diameter of the spacer to the average particle diameter of the solder particles is 1.1 or more and 15 or less.

In a specific aspect of the conductive paste of the present invention, the content of the spacer is 0.1 weight. The amount is more than 10% by weight.

In a specific aspect of the conductive paste of the present invention, the solder particles have an average particle diameter of 1 μm or more and 40 μm or less.

In a specific aspect of the conductive paste of the present invention, the content of the solder particles is 10% by weight or more and 80% by weight or less.

In a specific aspect of the conductive paste of the present invention, the ratio of the content of the solder particles in the unit of weight % to the content of the spacer in units of % by weight is 2 or more and 100 or less.

According to a broader aspect of the present invention, a connection structure comprising: a first connection member having at least one first electrode on a surface thereof; and a second connection member having at least one second surface on the surface And a connecting portion that connects the first connection target member and the second connection target member, wherein a material of the connection portion is the conductive paste, and the first electrode and the second electrode are in the connection portion The solder portion is electrically connected, and the spacer contacts both the first connection target member and the second connection target member.

According to a broad aspect of the present invention, a method of manufacturing a connection structure comprising: disposing the conductive paste on a surface of a first connection member having at least one first electrode on a surface thereof using the conductive paste described above a step of forming a second connection target member having at least one second electrode on the surface of the conductive paste opposite to the first connection target member side so that the first electrode and the second electrode face each other And the step of disposing the conductive paste to a temperature equal to or higher than a melting point of the solder particles and a hardening temperature of the thermosetting component to form the first connection target member and the second connection target by the conductive paste formation a connection portion to which the member is connected, and the first electrode and the second electrode are electrically connected by the solder portion in the connection portion, and the spacer is in contact with the first connection member and the second connection member The steps of both.

In a specific aspect of the manufacturing method of the connection structure of the present invention, the first When the electrode is electrically connected to the second electrode, the electrode is heated to a temperature equal to or higher than the melting point of the solder particles and the hardening temperature of the thermosetting component, and a plurality of the solder particles are aggregated and integrated.

In a specific aspect of the method for manufacturing a connection structure according to the present invention, the step of arranging the second connection member and the step of forming the connection portion are not performed, and the weight of the second connection member is applied to The above conductive paste.

The second connection target member is preferably a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate.

The conductive paste of the present invention comprises a thermosetting component, a plurality of solder particles, and a plurality of spacers having a melting point of 250 ° C or more. Therefore, the first connection member having the first electrode on the surface and the second electrode are provided on the surface. (2) When the connection target member is connected and the first electrode and the second electrode are electrically connected to each other, the interval between the electrodes can be controlled with high precision, and the solder particles can be efficiently disposed on the electrode, thereby improving Conductivity reliability between electrodes.

1, 1X, 1Y‧‧‧ connection structure

2, 2Y‧‧‧1st connection object component

2a‧‧‧1st electrode

2y‧‧‧1st convex

3, 3Y‧‧‧2nd connection object component

3a‧‧‧2nd electrode

3y‧‧‧2nd convex

4, 4X, 4Y‧‧‧ Connections

4A, 4XA, 4YA‧‧‧ solder department

4B, 4XB, 4YB‧‧‧ hardened parts

5, 5X, 5Y‧‧‧ spacers

11‧‧‧Electric paste

11A‧‧‧ solder particles

11B‧‧‧ thermosetting ingredients

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

2(a) to 2(c) are cross-sectional views for explaining respective steps of an example of a method of manufacturing a bonded structure using a conductive paste according to an embodiment of the present invention.

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

Fig. 4 is a cross-sectional view showing a variation of the connection structure.

Hereinafter, the details of the present invention will be described.

(conductive paste)

The conductive paste of the present invention is for using the first connection member having the first electrode on the surface The second connection target member having the second electrode on the surface thereof is connected to electrically connect the first electrode and the second electrode. The conductive paste of the present invention comprises a thermosetting component, a plurality of solder particles, and a plurality of spacers having a melting point of 250 ° C or higher.

In the conductive paste of the present invention, the average particle diameter of the spacer is larger than the average particle diameter of the solder particles.

Since the conductive paste of the present invention has the above configuration, when the electrodes are electrically connected to each other, the interval between the electrodes can be controlled with high precision. Further, when the solder particles are aggregated between the electrodes, the gap between the upper and lower electrodes is sufficiently ensured by the spacers. Therefore, a plurality of solder particles are easily aggregated between the electrodes facing each other, and a plurality of solder particles can be efficiently disposed. On the electrode (line). Further, it is difficult to arrange one of the plurality of solder particles in a region (gap) in which the electrode is not formed, and the amount of the solder particles disposed in the region where the electrode is not formed can be greatly reduced. Therefore, the conduction reliability between the electrodes can be improved. Further, it is possible to prevent electrical connection between adjacent electrodes which are not connectable in the lateral direction, and it is possible to improve insulation reliability. In the present invention, the solder particles can be efficiently disposed on the electrodes by blending the spacers. Further, in the present invention, not only the spacers but also the average particle diameter of the spacers and the solder particles are set within a specific range, so that the solder particles can be efficiently disposed on the electrodes. The use of spacers having a specific average particle size greatly contributes to the improvement of the amount of solder and the accuracy of placement between the upper and lower electrodes to be connected.

Since the average particle diameter of the spacer is larger than the average particle diameter of the solder particles, when the solder particles move on the electrode, the interval at which the solder particles can move between the first connection member and the second connection member is ensured. It promotes the movement of solder particles. As a result, since the amount of solder disposed between the upper and lower electrodes increases, the conduction reliability between the electrodes becomes high.

Further, in the present invention, it has been found that by using a spacer, the spacer not only controls the interval between the upper and lower electrodes, but also contributes to the improvement of the cohesiveness of the solder particles.

Further, the present invention can prevent positional displacement between electrodes. For the purposes of the present invention, When the second connection target member is superposed on the first connection target member to which the conductive paste is applied, the first position is shifted even when the alignment between the electrode of the first connection target member and the electrode of the second connection target member is shifted. When the connection target member and the second connection target member are overlapped, the offset may be corrected, and the electrode of the first connection target member may be connected to the electrode of the second connection target member (automatic alignment effect).

Further, when the conductive particles including the substrate particles not formed of the solder and the solder layer disposed on the surface of the substrate particles are used instead of the solder particles, the conductive particles become difficult on the electrode. Since the conductive particles are low in solder joint property, the conductive particles moving on the electrode are easily moved outside the electrode. Therefore, the suppression effect of the positional shift between the electrodes also becomes low.

In order to further efficiently dispose the solder particles on the electrode, the viscosity (η25) of the conductive paste at 25 ° C is preferably 10 Pa ‧ or more, more preferably 50 Pa ‧ or more, and still more preferably 100 Pa ‧ or more Preferably, it is 800 Pa‧s or less, more preferably 600 Pa‧s or less, further preferably 500 Pa‧s or less.

The viscosity (η25) can be appropriately adjusted depending on the type of the blending component and the blending amount. Moreover, by using a filler, the viscosity can be relatively increased.

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

The conductive paste of the present invention can be preferably used in the connection structure of the present invention and the method of producing the connection structure described below.

In view of further improving the conduction reliability, the conductive paste is preferably heated to a temperature equal to or higher than a melting point of the solder particles and a hardening temperature of the thermosetting component when the first electrode and the second electrode are electrically connected to each other. As described above, a plurality of the above-described solder particles are aggregated and integrated for use. A larger area of the solder portion is formed by the integration of a plurality of solder particles. In one solder portion, it is preferable that two or more solder particles in the conductive paste are integrated, and it is more preferable that three or more solder particles in the conductive paste are integrated, and further preferably Five or more solder particles in the electric paste are integrated.

The above conductive paste can be preferably used for electrical connection of electrodes. The above conductive paste is preferably a circuit connecting material.

Hereinafter, each component contained in the above-mentioned conductive paste will be described.

(solder particles)

The solder particles have solder on the surface other than the conductive layer. The solder particle center portion and the conductive outer surface are each formed of solder. The solder particles are the central portion of the solder particles and the outer surface of the conductive particles are solder particles.

From the viewpoint of efficiently agglomerating the solder particles on the electrode, it is preferable that the zeta potential of the surface of the solder particle is positive. However, in the present invention, the zeta potential of the surface of the solder particles may not be positive.

The zeta potential can be measured in the following manner.

Determination of zeta potential:

0.05 g of the solder particles was placed in 10 g of methanol, and ultrasonic treatment or the like was performed to uniformly disperse the solder particles to obtain a dispersion liquid. This dispersion can be used, and the zeta potential is measured at 23 ° C by an electrophoresis method using "Delsamax PRO" manufactured by Beckman Coulter.

The zeta potential of the solder particles is preferably 0 mV or more, more preferably more than 0 mV, and more preferably 10 mV or less, more preferably 5 mV or less, further preferably 1 mV or less, further preferably 0.7 mV or less, and particularly preferably 0.5 mV. the following. When the zeta potential is less than or equal to the above upper limit, the solder particles become difficult to aggregate in the conductive paste before use. When the zeta potential is 0 mV or more, the solder particles are efficiently aggregated on the electrode during mounting.

In order to make the zeta potential of the surface positive, the solder particles preferably have a solder particle body and an anionic polymer disposed on the surface of the solder particle body. The solder particles are preferably obtained by surface-treating the solder particles by using an anionic polymer or a compound which is an anionic polymer. The above solder particles are preferably It is a surface treatment of an anionic polymer or a compound which becomes an anionic polymer. The above-mentioned anionic polymer and the above-mentioned compound which becomes an anionic polymer may be used alone or in combination of two or more.

As a method of surface-treating a solder particle body by an anionic polymer, the method of synthesizing a (meth)acrylic- And a polyester polymer having a carboxyl group at both ends, a polymer obtained by intermolecular dehydration condensation reaction of a dicarboxylic acid and having a carboxyl group at both terminals, a polyester synthesized from a dicarboxylic acid and a diamine and having a carboxyl group at both terminals As an anionic polymer, a modified polyvinyl alcohol having a carboxyl group ("GOHSENX T" manufactured by Nippon Synthetic Chemical Co., Ltd.) or the like is used to react a carboxyl group of the anionic polymer with a hydroxyl group on the surface of the solder particle body.

Examples of the anion portion of the anionic polymer include the above-mentioned carboxyl group, and examples thereof include a toluenesulfonyl group (pH ₃ CC ₆ H ₄ S(=O) ₂ -) and a sulfonate ion group (-SO ₃ ^-). ), and a phosphate ion group (-PO ₄ ^- ).

Moreover, as another method, a method of using a functional group having a functional group reactive with a hydroxyl group on the surface of the solder particle main body and further having a functional group capable of being polymerized by addition or condensation reaction is used, and the compound is used. Polymerization is carried out on the surface of the solder particle body. Examples of the functional group that reacts with the hydroxyl group on the surface of the main body of the solder particles include a carboxyl group and an isocyanate group. Examples of the functional group to be polymerized by addition or condensation reaction include a hydroxyl group, a carboxyl group, and an amine group. And (meth) acrylonitrile.

The weight average molecular weight of the above anionic polymer is preferably 2,000 or more, more preferably 3,000 or more, and is preferably 10,000 or less, more preferably 8,000 or less.

When the weight average molecular weight is at least the above lower limit and not more than the above upper limit, the anionic polymer is easily disposed on the surface of the solder particle body, and the zeta potential of the surface of the solder particles is easily made positive, and the electrode can be further efficiently applied to the electrode. Configure solder particles.

The above weight average molecular weight is measured by gel permeation chromatography (GPC). The weight average molecular weight in terms of polystyrene.

The weight average molecular weight of the polymer obtained by surface-treating the solder particle body by using a compound which becomes an anionic polymer can be obtained by dissolving the solder in the solder particles without causing decomposition of the polymer. After the solder particles are removed by dilute hydrochloric acid or the like, the weight average molecular weight of the remaining polymer is measured.

The above 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 (low melting point metal particles) having a melting point of 450 ° C or lower. The low melting point metal particles are particles containing a low melting point metal. The low melting point metal is a metal having a melting point of 450 ° C or lower. The melting point of the low melting point metal is preferably 300 ° C or lower, more preferably 160 ° C or lower. Further, the solder particles 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 at least the above lower limit, the connection reliability between the solder portion and the electrode is further increased.

In addition, the high-frequency inductively coupled plasma emission spectrometer ("ICP-AES" manufactured by Horiba, Ltd.) or the fluorescent X-ray analyzer (EDX-800HS manufactured by Shimadzu Corporation) can be used. And the measurement is performed.

By using the above-described solder particles, the solder is melted and bonded to the electrodes, so that the solder portions electrically conduct the electrodes. For example, since the solder portion and the electrode are easily in surface contact and are not in point contact, the connection resistance is lowered. Moreover, by using the solder particles, the bonding strength between the solder portion and the electrode is increased, and as a result, the peeling of the solder portion and the electrode is further prevented from occurring, and the conduction reliability and the connection reliability are effectively increased.

The metal (low melting point metal) constituting the solder particles is not particularly limited. The low melting point metal is preferably tin or an alloy containing tin. Examples of the alloy include a tin-silver alloy, a tin-copper alloy, a tin-silver-copper alloy, a tin-bismuth alloy, a tin-zinc alloy, and a tin-indium alloy. In terms of excellent wettability to the electrode, the low melting point metal is preferably tin, tin-silver. Gold, tin-silver-copper alloy, tin-bismuth alloy, tin-indium alloy. More preferably, it is a tin-bismuth alloy or a tin-indium alloy.

The solder particles are preferably a weld filler material having a liquidus of 450 ° C or less based on JIS Z3001: welding term. Examples of the composition of the solder particles include a metal composition containing zinc, gold, silver, lead, copper, tin, antimony, indium, or the like. A tin-indium system (117 ° C eutectic) or a tin-lanthanide (139 ° C eutectic) having a low melting point and no lead is preferable. That is, the solder particles preferably do not contain lead, and preferably contain tin and indium, or contain tin and antimony.

In order to further improve the bonding strength between the solder portion and the electrode, the solder particles may further comprise nickel, copper, lanthanum, aluminum, zinc, lanthanum, gold, titanium, phosphorus, lanthanum, cerium, cobalt, lanthanum, manganese, chromium, molybdenum, Metal such as palladium. Further, from the viewpoint of further improving the bonding strength between the solder portion and the electrode, the solder particles preferably contain nickel, copper, ruthenium, aluminum or zinc. From the viewpoint of further improving the bonding strength between the solder portion and the electrode, the content of the metal for improving the bonding strength is preferably 0.0001% by weight or more, preferably 1% by weight or less, based on 100% by weight of the solder particles.

The average particle diameter of the solder particles is preferably 0.5 μm or more, more preferably 1 μm or more, further preferably 3 μm or more, particularly preferably 5 μm or more, and preferably 100 μm or less, more preferably less than 80 μm, and thus more preferably It is 75 μm or less, more preferably 60 μm or less, still more preferably 40 μm or less, still more preferably 30 μm or less, still more preferably 20 μm or less, still more preferably 15 μm or less, and most preferably 10 μm or less. When the average particle diameter of the solder particles is not less than the above lower limit and not more than the above upper limit, the solder particles can be more efficiently disposed on the electrode. The average particle diameter of the solder particles is preferably 3 μm or more and 30 μm or less.

The "average particle diameter" of the above solder particles means a number average particle diameter. Regarding the average particle diameter of the solder particles, for example, an arbitrary value is obtained by observing any 50 solder particles by an electron microscope or an optical microscope, or by performing laser diffraction type particle size distribution measurement. Out.

The coefficient of variation of the particle diameter of the solder particles is preferably 5% or more, more preferably 10% or more, and is preferably 40% or less, more preferably 30% or less. When the coefficient of variation of the particle diameter is not less than the above lower limit and not more than the above upper limit, the solder particles can be more efficiently disposed on the electrode. However, the coefficient of variation of the particle diameter of the above solder particles may be less than 5%.

The above coefficient of variation (CV value) is represented by the following formula.

CV value (%) = (ρ / Dn) × 100

ρ: standard deviation of the particle size of the solder particles

Dn: average of the particle size of the solder particles

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

The content of the solder particles in 100% by weight of the conductive paste is preferably 1% by weight or more, more preferably 2% by weight or more, still more preferably 10% by weight or more, still more preferably 20% by weight or more, and most preferably 30% by weight. The weight% or more is preferably 80% by weight or less, more preferably 60% by weight or less, still more preferably 50% by weight or less. When the content of the solder particles is not less than the above lower limit and not more than the above upper limit, the solder particles can be more efficiently disposed on the electrode, and a large amount of solder particles are easily disposed between the electrodes, and the conduction reliability is further increased. From the viewpoint of further improving the conduction reliability, it is preferred that the content of the solder particles is large.

When the line (L) in which the electrode is formed is 50 μm or more and less than 150 μm, the content of the solder particles is preferably 20% by weight of the conductive paste 100% by weight. The weight% or more is more preferably 30% by weight or more, and is preferably 55% by weight or less, more preferably 45% by weight or less.

When the gap (S) of the portion where the electrode is not formed is 50 μm or more and less than 150 μm, the content of the solder particles is preferably 30% by weight of the conductive paste 100% by weight. More than weight%, more preferably 40% by weight The upper portion is preferably 70% by weight or less, more preferably 60% by weight or less.

When the line (L) where the electrode is formed is 150 μm or more and less than 1000 μm, the content of the solder particles is preferably 30% by weight of the conductive paste 100% by weight. The weight% or more is more preferably 40% by weight or more, and is preferably 70% by weight or less, more preferably 60% by weight or less.

When the gap (S) of the portion where the electrode is not formed is 150 μm or more and less than 1000 μm, the content of the solder particles is preferably 30% in 100% by weight of the conductive paste. The weight% or more is more preferably 40% by weight or more, and is preferably 70% by weight or less, more preferably 60% by weight or less.

(spacer)

The spacer may be preferably used in such a manner as to be in contact with both the first connection member and the second connection member. Therefore, the conductive paste of the present invention can be preferably used in such a manner that the spacer is in contact with both the first connection target member and the second connection target member. The spacer may be in contact with the first electrode (the region in which the first electrode is provided) of the first connection member and the second electrode (the region in which the second electrode is provided) of the second connection member The method is preferably used. The spacer may be preferably used in contact with both the region where the first electrode is not provided and the region where the second electrode is not provided in the second connection member. Since the solder is intended to agglomerate between the electrodes during the conductive connection, the spacer is likely to move to the region where the electrode is not provided. On the other hand, there is a case where the spacer is disposed between the electrodes.

The above separator has a melting point of 250 ° C or higher. In order to electrically connect the first electrode and the second electrode, the spacer is not melted and the melting point is set high. The upper limit of the melting point of the above spacer is not particularly limited. The above-mentioned spacer may have a melting point of 400 ° C or less.

The melting point of the spacer is preferably 300 ° C or higher, more preferably 350 ° C or higher, from the viewpoint of further preventing melting of the spacer.

The spacer may also be a resin particle. Examples of the material of the resin particles include a polyolefin resin, an acrylic resin, a phenol resin, a melamine resin, a benzoguanamine resin, a urea resin, an epoxy resin, an unsaturated polyester resin, a saturated polyester resin, and a polyparaphenylene. Ethylene dicarboxylate, polyfluorene, polyphenylene ether, polyacetal, polyimide, polyamidoximine, polyetheretherketone, polyether oxime, divinylbenzene polymer, and ethylene benzene-styrene A copolymer or a divinylbenzene copolymer such as a divinylbenzene-(meth)acrylate copolymer. Since the hardness of the resin particles can be easily controlled to a preferred range, the material of the resin particles is preferably a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group. . In particular, a divinylbenzene polymer, a polyimine or a polyamidimide is preferred.

Further, as the material of the spacer, in addition to the resin, cerium oxide, glass, quartz, polyfluorene oxide, metal, metal oxide or the like may be mentioned. The material of the spacer may also be not a metal. The material of the spacer is preferably a resin, more preferably a divinylbenzene copolymer. The divinylbenzene-based copolymer contains, for example, divinylbenzene as a copolymerization component.

Since the spacers are disposed between the adjacent electrodes in the lateral direction, the spacers are preferably insulating particles from the viewpoint of further improving the insulation reliability.

The average particle diameter of the spacer is preferably 10 μm or more, more preferably 20 μm or more, further preferably 25 μm or more, and more preferably 100 μm or less, more preferably 75 μm or less, and still more preferably 50 μm or less. When the average particle diameter of the spacer is not less than the above lower limit and not more than the above upper limit, the interval between the electrodes can be controlled with higher precision, and the solder particles can be more efficiently disposed on the electrode.

The "average particle diameter" of the above spacers means a number average particle diameter. The average particle diameter of the spacer is, for example, an average value calculated by observing any 50 spacers by an electron microscope or an optical microscope, or by performing laser diffraction type particle size distribution measurement.

The average particle diameter of the spacer is larger than the average particle diameter of the solder particles from the viewpoint of efficiently controlling the electrodes and efficiently disposing the solder on the electrodes.

Further control the electrode between the electrodes with high precision, and further efficiently configure the solder From the viewpoint of the electrode, the ratio of the average particle diameter of the spacer to the average particle diameter of the solder particles (the average particle diameter of the spacer/the average particle diameter of the solder particles) is preferably 1.1 or more, more preferably 1.5 or more, further preferably 2 or more, and preferably 15 or less, more preferably 10 or less, further preferably 8 or less. The ratio of the average particle diameter of the spacer to the average particle diameter of the solder particles (the average of the spacers) from the viewpoint of further controlling the inter-electrode with high precision and further efficiently disposing the solder on the electrode The particle diameter/average particle diameter of the solder particles is preferably 1.0 or more, more preferably 1.5 or more, and is preferably 15 or less, more preferably 10 or less.

The coefficient of variation of the particle diameter of the spacer is preferably 3% or more, more preferably 5% or more, and is preferably 30% or less, more preferably 20% or less. When the coefficient of variation of the particle diameter is not less than the above lower limit and not more than the above upper limit, the interval between the electrodes can be controlled with higher precision.

The above coefficient of variation (CV value) is represented by the following formula.

CV value (%) = (ρ / Dn) × 100

ρ: standard deviation of the particle size of the spacer

Dn: average of the particle size of the spacer

From the viewpoint of further accurately controlling the inter-electrode and further efficiently disposing the solder on the electrode, the content of the solder particles in the unit of weight % (in 100% by weight of the conductive paste) is relative to the spacer The ratio (content of the solder particles (% by weight) / content of the spacer (% by weight)) in terms of the content by weight % (in 100% by weight of the conductive paste) is preferably 2 or more, more preferably 5 or more, and further It is preferably 10 or more, and is preferably 100 or less, more preferably 80 or less, and still more preferably 70.

The 10% K value (compressive elastic modulus at the time of compression of 10%) of the spacer is preferably 2000 N/mm from the viewpoint of further controlling the inter-electrode with high precision and further efficiently disposing the solder on the electrode. ² or more is more preferably 3500 N/mm ² or more, and is preferably 8000 N/mm ² or less, more preferably 6000 N/mm ² or less. Further, when the 10% K value of the spacer is not less than the lower limit and not more than the upper limit, it is possible to prevent excessive movement of the spacer after the spacer contacts both the first electrode and the second electrode, thereby promoting aggregation of the solder particles. Further, the positional deviation between the first electrode and the second electrode can be prevented, and the conduction reliability can be improved.

The 10% K value of the above spacer can be measured in the following manner.

The spacer was compressed under the condition of applying a maximum test load of 90 mN at 25 ° C for 30 seconds using a small compression tester with a smooth indenter end face of a cylinder (diameter 50 μm, made of diamond). The load value (N) and the compression displacement (mm) at this time were measured. The compression elastic modulus can be obtained from the measured value obtained by the following formula. As the micro compression tester, for example, "Fischerscope H-100" manufactured by Fischer Co., Ltd. or the like can be used.

K value (N/mm ² )=(3/2 ^1/2 )‧F‧S ^-3/2 ‧R ^-1/2

F: load value at 10% compression deformation of the spacer (N)

S: Compression displacement (mm) when the spacer is deformed by 10%

R: radius of the spacer (mm)

The compression recovery ratio of the spacer is preferably 30% or more, more preferably 40% or more, and more preferably from the viewpoint of further accurately controlling the inter-electrode and further disposing the solder on the electrode. 80% or less, more preferably 70% or less. In addition, when the compression recovery ratio of the spacer is equal to or higher than the lower limit and equal to or less than the upper limit, it is possible to prevent excessive movement of the spacer after the spacer contacts both the first electrode and the second electrode, thereby promoting aggregation of the solder particles. Further, the positional deviation between the first electrode and the second electrode can be prevented, and the conduction reliability can be improved.

The above compression recovery rate can be measured in the following manner.

Spacers are scattered on the sample stage. A small compression tester was used to apply a load (reverse load value) to the center of the spacer at 25 ° C using a small compression tester with a smooth end face of a cylinder (100 μm in diameter, made of diamond). The object is compressed and deformed by 40%. Thereafter, the load is released until the origin load value (0.40 mN). The load-compression displacement during this period can be measured, and the compression recovery rate can be obtained from the following equation. In addition, the load speed will be applied. The degree is set to 0.33 mN/sec. As the micro compression tester, for example, "Fischerscope H-100" manufactured by Fischer Co., Ltd. or the like can be used.

Compression recovery rate (%) = [(L1-L2) / L1] × 100

L1: Compression displacement from the origin load value to the reverse phase load value when the load is applied

L2: The self-reverse load value at the time of load release until the load value of the origin load is released

The content of the spacer in 100% by weight of the conductive paste is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, further preferably 1% by weight or more, and preferably 10% by weight or less, more preferably It is 5% by weight or less, more preferably 4% by weight or less, and still more preferably 3% by weight or less. When the content of the spacer is not less than the above lower limit and not more than the above upper limit, the interval between the electrodes can be controlled with higher precision, and the solder particles can be more efficiently disposed on the electrode, and the electrode can be easily disposed between the electrodes. Solder particles, so that the conduction reliability is further increased.

(thermosetting compound: thermosetting component)

The above thermosetting compound is a compound which can be hardened by heating. Examples of the thermosetting compound include an oxetane compound, an epoxy compound, an episulfide compound, a (meth)acrylic compound, a phenol compound, an amine compound, an unsaturated polyester compound, and a polyamine group. a formate compound, a polyoxymethylene compound, a polyimine compound, and the like. An epoxy compound is preferred from the viewpoint of further improving the curing property and viscosity of the conductive paste and further improving the connection reliability.

The content of the thermosetting compound in the 100% by weight of the conductive paste is preferably 20% by weight or more, more preferably 40% by weight or more, further preferably 50% by weight or more, and preferably 99% by weight or less. It is preferably 98% by weight or less, more preferably 90% by weight or less, and still more preferably 80% by weight or less. From the viewpoint of further improving the impact resistance, it is preferred that the content of the thermosetting component is large.

(thermosetting agent: thermosetting component)

The above-mentioned thermosetting agent thermally hardens the above thermosetting compound. Examples of the above-mentioned thermosetting agent include a thiol curing agent such as an imidazole curing agent, an amine curing agent, a phenol curing agent, and a polythiol curing agent, an acid anhydride, a thermal cation initiator (thermal cation hardener), and thermal radical generation. Agents, etc. These thermosetting agents may be used alone or in combination of two or more.

The imidazole hardener, the thiol hardener or the amine hardener is preferred because the conductive paste can be further hardened at a low temperature. Further, it is preferable that the latent curing agent is highly stable in storage stability by mixing the curable compound which can be cured by heating and the above-mentioned thermosetting agent. The latent hardener is preferably a latent imidazole hardener, a latent thiol hardener or a latent amine hardener. Further, the thermal curing agent may be coated with a polymer material such as a polyurethane resin or a polyester resin.

The imidazole curing agent is not particularly limited, and examples thereof include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, and 1-cyanoethyl-2. -Phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-symmetric III And 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-symmetric three An isocyanuric acid addition product or the like.

The thiol curing agent is not particularly limited, and examples thereof include trimethylolpropane tri-3-mercaptopropionate, pentaerythritol tetrakis-mercaptopropionate, and dipentaerythritol hexa-3-mercaptopropionate. .

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

Examples of the thermal cation initiator include a lanthanoid cation curing agent, an oxonium cation curing agent, and a lanthanoid cation curing agent. The ruthenium-based cation hardener may, for example, be bis(4-tert-butylphenyl)phosphonium hexafluorophosphate. Examples of the oxonium-based cationic curing agent include trimethyloxonium tetrafluoroborate. Examples of the ruthenium-based cationic curing agent include tri-p-triazine hexafluorophosphate and the like.

The thermal radical generating agent is not particularly limited, and examples thereof include an azo compound and an organic peroxide. 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 above-mentioned thermosetting agent is preferably 50 ° C or more, more preferably 70 ° C or more, further preferably 80 ° C or more, and preferably 250 ° C or less, more preferably 200 ° C or less, and further preferably Below 150 ° C, particularly preferably below 140 ° C. When the reaction initiation temperature of the thermal curing agent is not less than the above lower limit and not more than the above upper limit, the solder particles are more efficiently disposed on the electrode. The reaction initiation temperature of the above-mentioned thermosetting agent is particularly preferably 80 ° C or more and 140 ° C or less.

The reaction initiation temperature of the thermal curing agent is preferably higher than the melting point of the solder in the solder particles, more preferably 5 ° C or higher, and further preferably from the viewpoint of further efficiently disposing the solder on the electrode. It is above 10 °C.

The reaction initiation temperature of the above-mentioned thermosetting agent means a temperature at which the rise of the heat generation peak based on DSC (Differential Scanning Calorimetry) starts.

The content of the above-mentioned thermosetting agent is not particularly limited. The content of the above-mentioned 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 100 parts by weight or less, based on 100 parts by weight of the thermosetting compound. Further, it is preferably 75 parts by weight or less. When the content of the thermosetting agent is at least the above lower limit, the conductive paste is easily cured sufficiently. When the content of the thermal curing agent is at most the above upper limit, the excessive amount of the hard curing agent that does not participate in curing after hardening becomes difficult to remain, and the heat resistance of the cured product is further increased.

(flux)

The above conductive paste preferably contains a flux. The solder can be further effectively disposed on the electrode by using a flux. The flux is not particularly limited. As the flux, a flux which is usually used such as solder bonding can be used. As the above flux, for example, it can be listed A zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, a molten salt, a phosphoric acid, a derivative of phosphoric acid, an organic halide, a hydrazine, an organic acid, and a rosin. The flux may be used alone or in combination of two or more.

Examples of the molten salt include ammonium chloride and the like. Examples of the organic acid include lactic acid, citric acid, stearic acid, glutamic acid, and glutaric acid. Examples of the rosin include activated rosin and inactivated rosin. The flux is preferably an organic acid or rosin having two or more carboxyl groups. The flux may be an organic acid having two or more carboxyl groups, or may be a rosin having two or more carboxyl groups. By using an organic acid or rosin having two or more carboxyl groups, the conduction reliability between the electrodes is further increased.

The above rosin is a rosin mainly composed of rosin acid. The flux is preferably rosin, more preferably rosin acid. By using the preferred flux, the conduction reliability between the electrodes is further increased.

The active temperature (melting point) of the flux is preferably 50 ° C or higher, more preferably 70 ° C or higher, further preferably 80 ° C or higher, and preferably 200 ° C or lower, more preferably 190 ° C or lower, and further preferably It is 160 ° C or lower, more preferably 150 ° C or lower, and still more preferably 140 ° C or lower. When the activation temperature of the flux is not less than the above lower limit and not more than the above upper limit, the effect of the flux is further effectively exhibited, and the solder particles are more efficiently disposed on the electrode. The active temperature of the above flux is preferably 80 ° C or more and 190 ° C or less. The active temperature of the above flux is particularly preferably 80 ° C or more and 140 ° C or less.

Examples of the flux having a melting point of 80 ° C or more and 190 ° C or less include succinic acid (melting point 186 ° C), glutaric acid (melting point 96 ° C), adipic acid (melting point 152 ° C), and pimelic acid (melting point 104). °C), dicarboxylic acid such as suberic acid (melting point 142 ° C), benzoic acid (melting point 122 ° C), malic acid (melting point 130 ° C) and the like.

Further, the flux has a boiling point of preferably 200 ° C or lower.

The melting point of the flux is preferably higher than the melting point of the solder in the solder particles, more preferably 5 ° C, from the viewpoint of further efficiently disposing the solder on the electrode. Further, it is preferably 10 ° C or more higher.

The melting point of the flux is preferably higher than the reaction initiation temperature of the thermal curing agent, more preferably 5 ° C or higher, and further preferably 10 higher, from the viewpoint of further efficiently disposing the solder on the electrode. Above °C.

The solder particles can be efficiently agglomerated at the electrode portion by the melting point of the flux being higher than the melting point of the solder. The reason for this is that when heat is applied during bonding, the electrode formed on the member to be connected is compared with the portion of the member to be connected around the electrode, and the thermal conductivity of the electrode portion is higher than that of the member to be connected around the electrode. The thermal conductivity is such that the temperature of the electrode portion is increased faster. At the stage of exceeding the melting point of the solder particles, the inside of the solder particles is melted, but the oxide film formed on the surface does not reach the melting point (active temperature) of the flux, and thus is not removed. In this state, since the temperature of the electrode portion first reaches the melting point (active temperature) of the flux, the oxide film on the surface of the solder particles on the electrode is preferentially removed, so that the solder particles can be wetted on the surface of the electrode. diffusion. Thereby, the solder particles can be efficiently aggregated on the electrode.

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

The flux is preferably a flux that releases cations by heating. By using a flux that releases cations by heating, the solder particles can be further efficiently disposed on the electrodes.

The content of the flux in 100% by weight of the conductive paste is preferably 0.5% by weight or more, and preferably 30% by weight or less, more preferably 25% by weight or less. The above conductive paste may not contain a flux. When the content of the flux is not less than the above lower limit and not more than the above upper limit, it is further 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 can be more effectively removed.

(filler)

A filler may also be added to the above conductive paste. The filler may be an organic filler or may be Machine packing. By adding a filler, the distance at which the solder particles are agglomerated can be suppressed, and the solder particles can be uniformly aggregated on all the electrodes of the substrate.

The content of the filler in 100% by weight of the conductive paste is preferably 0% by weight or more, more preferably 5% by weight or less, still more preferably 2% by weight or less, still more preferably 1% by weight or less. When the content of the filler is not less than the above lower limit and not more than the above upper limit, the solder particles are more efficiently disposed on the electrode.

(other ingredients)

The above conductive paste may also contain, for example, a filler, a bulking agent, a softener, a plasticizer, a polymerization catalyst, a hardening catalyst, a colorant, an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, and a lubricant. Various additives such as agents, antistatic agents and flame retardants.

(Manufacturing method of connection structure and connection structure)

The connection structure according to the present invention includes: a first connection target member having at least one first electrode on a surface thereof; a second connection target member having at least one second electrode on a surface thereof; and a connection portion that performs the above The connection object member is connected to the second connection object member. In the connection structure of the present invention, the connecting portion is formed of the above-mentioned conductive paste, and is a cured product of the above-mentioned conductive paste. In the connection structure of the present invention, the material of the connecting portion is the above-mentioned conductive paste. In the connection structure of the present invention, the first electrode and the second electrode are electrically connected by a solder portion of the connection portion. Preferably, the spacer is in contact with both the first connection target member and the second connection target member.

The method for producing a connection structure according to the present invention includes the step of disposing the conductive paste on a surface of a first connection member having at least one first electrode on the surface thereof by using the conductive paste, and the conductive paste a step of arranging the second connection member having at least one second electrode on the surface opposite to the first connection target member so that the first electrode and the second electrode face each other; The conductive paste is heated to a temperature equal to or higher than a melting point of the solder particles and a hardening temperature of the thermosetting component, and the first connection member and the second connection pair are formed by the conductive paste. a step of electrically connecting the first electrode and the second electrode by a solder portion of the connecting portion. Preferably, the spacer is in contact with both the first connection target member and the second connection target member.

In the connection structure of the present invention and the method for producing the connection structure of the present invention, since a specific conductive paste is used, a plurality of solder particles are easily aggregated between the first electrode and the second electrode, and the electrode can be efficiently aggregated. A plurality of solder particles are disposed on the electrodes (lines). Further, it is difficult to arrange one of the plurality of solder particles in a region (gap) in which the electrode is not formed, and the amount of the solder particles disposed in the region where the electrode is not formed can be greatly reduced. Therefore, the conduction reliability between the first electrode and the second electrode can be improved. Further, it is possible to prevent electrical connection between adjacent electrodes which are not connectable in the lateral direction, and it is possible to improve insulation reliability.

From the viewpoint of further improving the conduction reliability, when the first electrode and the second electrode are electrically connected to each other, it is preferably heated to a temperature equal to or higher than a melting point of the solder particles and a hardening temperature of the thermosetting component. A plurality of the above solder particles are aggregated and integrated.

Moreover, the inventors of the present invention have found that in order to efficiently dispose a plurality of solder particles on an electrode and to reduce the amount of solder particles disposed in a region where no electrode is formed, it is necessary to use a conductive paste instead of a conductive film.

In the present invention, another method of efficiently agglomerating a plurality of solder particles between electrodes may be employed. In a method of efficiently agglomerating a plurality of solder particles between the electrodes, when the heat is applied to the conductive paste between the first connection member and the second connection member, the viscosity of the conductive paste is lowered by heat. Thereby, a method of generating convection of the conductive paste between the first connection target member and the second connection target member is performed. In the method, a method of generating convection by a difference in heat capacity between an electrode on the surface of the member to be connected and a surface member other than the surface member is used; and the convection is generated by causing the moisture of the member to be connected to be water vapor by heat. And a method of generating convection by a temperature difference between the first connection target member and the second connection target member. Thereby, the welding in the conductive paste can be obtained The particles move efficiently toward the surface of the electrode.

In the present invention, a method of selectively agglomerating solder particles on the surface of the electrode may be employed. The method of selectively agglomerating the solder particles on the surface of the electrode includes selecting an electrode member having a high wettability of the molten solder particles and a surface member formed of another surface material having poor wettability of the molten solder particles. Selectively attaching molten solder particles reaching the surface of the electrode to the electrode to melt and adhere the other solder particles to the molten solder particles; selecting an electrode material having good thermal conductivity and other surface having poor thermal conductivity a method of connecting a member to be formed by a material, wherein the temperature of the electrode is higher than that of the other surface member when heat is applied, thereby selectively melting the solder on the electrode; and a negative charge existing on the electrode formed of the metal a method of selectively agglomerating solder particles on an electrode using solder particles treated with a positive charge, and a solder particle in the conductive paste with respect to an electrode having a hydrophilic metal surface The resin is made hydrophobic, whereby a method of selectively agglomerating solder particles on an electrode or the like is provided.

The thickness of the solder portion between the electrodes is preferably 10 μm or more, more preferably 20 μm or more, and is preferably 100 μm or less, more preferably 80 μm or less. The solder wetted area on the surface of the electrode (the area in contact with the solder in 100% of the area exposed by the electrode) is preferably 50% or more, more preferably 60% or more, still more preferably 70% or more, and is preferably. It is 100% or less.

In the method of manufacturing the connection structure of the present invention, preferably, the step of arranging the second connection member and the step of forming the connection portion are not performed, and the weight of the second connection member is applied to the conductive a paste, or a step of pressurizing at least one of the step of arranging the second connection member and the step of forming the connection portion, and the step of arranging the second connection member and the step of forming the connection portion In the middle, the pressure of the pressurization is less than 1 MPa. The aggregation of the solder particles is considerably promoted by applying a pressure of pressurization of 1 MPa or more. From the viewpoint of suppressing warpage of the member to be connected, in the method of manufacturing the connection structure of the present invention, the second portion may be disposed Pressurization is performed in at least one of the step of connecting the target member and the step of forming the connecting portion, and in the step of arranging the second connecting member and the step of forming the connecting portion, the pressure of pressurization is not Up to 1MPa. In the case of pressurization, the pressurization may be performed only in the step of arranging the second connection member, or the pressurization may be performed only in the step of forming the connection portion, or the second connection member may be disposed. The step is performed in both the step of forming the above-described connecting portion. The pressure of the pressurization is less than 1 MPa, and the case where no pressurization is performed. In the case of pressurization, the pressure of pressurization is preferably 0.9 MPa or less, more preferably 0.8 MPa or less. When the pressure of the pressurization is 0.8 MPa or less, the aggregation of the solder particles is further remarkably promoted as compared with the case where the pressure of the pressurization exceeds 0.8 MPa.

In the method of manufacturing the connection structure of the present invention, preferably, the step of arranging the second connection member and the step of forming the connection portion are not performed, and the weight of the second connection member is applied to the conductive Preferably, in the step of arranging the second connection member and the step of forming the connection portion, a pressing pressure exceeding a weight of the second connection member is not applied to the conductive paste. In such cases, the uniformity of the amount of solder in the plurality of solder portions can be further improved. Further, the thickness of the solder portion can be further effectively increased, and a plurality of solder particles can be easily aggregated in a large amount between the electrodes, and a plurality of solder particles can be more efficiently disposed on the electrodes (wires). Further, it is difficult to arrange one of the plurality of solder particles in a region (gap) in which the electrode is not formed, and the amount of the solder particles disposed in the region where the electrode is not formed can be further reduced. Therefore, the conduction reliability between the electrodes can be further improved. Further, it is possible to further prevent electrical connection between adjacent electrodes which are not connectable in the lateral direction, and it is possible to further improve insulation reliability.

Further, the inventors have found that the weight of the second connection member is applied to the conductive paste before the connection portion is formed, in the step of arranging the second connection member and the step of forming the connection portion. Configured in an area where no electrode is formed (gap) Further, the solder particles are more easily aggregated between the first electrode and the second electrode, and a plurality of solder particles can be more efficiently disposed on the electrode (line). In the present invention, in order to obtain the effect of the present invention at a higher level, a conductive paste is used instead of the conductive film, and the weight of the second connection member is applied to the conductive paste without being pressurized. The situation in which the combination is used is of great significance.

Further, in WO 2008/023452 A1, it is described that, in view of the fact that the surface of the electrode is impacted by the solder powder and moved efficiently, it is also possible to pressurize at a specific pressure in the subsequent pressure, regarding the pressurizing pressure. In the case where the solder region is formed in a stable manner, for example, it is set to 0 MPa or more, preferably 1 MPa or more, and it is described that even if the pressure to be applied to the subsequent tape is 0 MPa, it may be borrowed. The specific pressure is applied to the subsequent belt by the weight of the member disposed on the belt. In WO 2008/023452 A1, the case where the pressure to be applied to the subsequent belt is 0 MPa is described. However, the difference in the effect of the case where the pressure exceeds 0 MPa and the case where the pressure is 0 MPa is not described. Further, in WO 2008/023452 A1, there is no knowledge about the importance of using a paste-like conductive paste instead of a film.

Further, when a conductive paste is used instead of the conductive film, the thickness of the connection portion and the solder portion can be easily adjusted according to the amount of the conductive paste applied. On the other hand, in the case of the conductive film, there is a problem in that in order to change or adjust the thickness of the connection portion, it is necessary to prepare a conductive film of a different thickness or prepare a conductive film of a specific thickness. Moreover, the conductive film has a problem that the melting viscosity of the conductive film cannot be sufficiently lowered at the melting temperature of the solder, and the aggregation of the solder particles is hindered.

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 connection structure obtained by using a conductive paste according to an embodiment of the present invention.

The connection structure 1 shown in Fig. 1 includes a first connection target member 2 and a second connection object. The member 3 and the connecting portion 4 that connects the first connecting object member 2 and the second connecting target member 3. The connecting portion 4 is formed of a conductive paste containing a thermosetting compound, a thermosetting agent, a plurality of solder particles, and a plurality of spacers 5. The thermosetting compound and the thermosetting agent are thermosetting components.

The connection portion 4 has a solder portion 4A in which a plurality of solder particles are aggregated and joined to each other, a cured portion 4B in which a thermosetting component is thermally cured, and a spacer 5.

The first connection target member 2 has a plurality of first electrodes 2a on the surface (upper surface). The second connection target member 3 has a plurality of second electrodes 3a on the surface (lower surface). The first electrode 2a and the second electrode 3a are electrically connected by the 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. Further, in the connection portion 4, solder is not present in a region (a portion of the cured portion 4B) different from the solder portion 4A that is aggregated between the first electrode 2a and the second electrode 3a. There is no solder separated from the solder portion 4A in a region different from the solder portion 4A (the portion of the cured portion 4B). In addition, in a small amount, solder may be present in a region (a portion of the cured portion 4B) different from the solder portion 4A that is aggregated between the first electrode 2a and the second electrode 3a.

The spacer 5 is in contact with both the first electrode 2a of the first connection member 2 and the second electrode 3a of the second connection member 3. The gap between the first connection target member 2 and the second connection target member 3 is controlled by the spacer 5, and the distance between the first electrode 2a and the second electrode 3a is controlled. The spacer 5 may be in contact with both the region where the first electrode 2a is not provided in the first connection member 2 and the region where the second electrode 3a is not provided in the second connection member 3.

As shown in FIG. 1, in the connection structure 1, a plurality of solder particles are aggregated between the first electrode 2a and the second electrode 3a, and after a plurality of solder particles are melted, the melt of the solder particles is wetted and diffused on the surface of the electrode. Thereafter, curing is performed to form the solder portion 4A. Therefore, the connection area between the solder portion 4A and the first electrode 2a and the solder portion 4A and the second electrode 3a is increased. In other words, by using solder particles, the solder portion 4A and the first electrode 2a, and the solder portion 4A and the second portion are used as compared with the case where conductive particles having a conductive outer surface of a metal such as nickel, gold or copper are used. The contact area of the electrode 3a becomes large. Therefore, the conduction reliability and the connection reliability in the connection structure 1 become high. Further, the conductive paste may also contain a flux. In the case of using a flux, the flux is gradually deactivated by heating.

Further, in the connection structure 1 shown in Fig. 1, the solder portions 4A are all located in the opposing regions between the first and second electrodes 2a and 3a. The connection structure 1X of the variation shown in FIG. 3 is different from the connection structure 1 shown in FIG. 1 only in the connection portion 4X. The connecting portion 4X has a solder portion 4XA, a cured portion 4XB, and a spacer 5X. As in the case of the connection structure 1X, the solder portion 4XA may be located in a region where the first and second electrodes 2a and 3a face each other, and a portion of the solder portion 4XA may be opposed to the first and second electrodes 2a and 3a. The area overflows to the side. One of the solder portions 4XA-based solder portions 4XA that overflows from the opposing regions of the first and second electrodes 2a and 3a is not solder separated from the solder portion 4XA. Further, in the present embodiment, the amount of solder separated from the solder portion can be reduced, but the solder separated from the solder portion may be present in the cured portion.

When the amount of use of the solder particles is reduced, the connection structure 1 is easily obtained. When the amount of use of the solder particles is increased, the connection structure 1X is easily obtained. Further, as long as the solder wets and spreads on the surface of the electrode, the solder does not necessarily aggregate between the upper and lower electrodes.

In the same manner as the connection structure 1Y shown in FIG. 4, the first connection object having the first protrusion 2y on the surface and the first electrode 2a on the first electrode 2a side and having the first protrusion 2y may be used. The member 2Y has the second electrode 3a on the surface, and the second connection member 3Y having the second convex portion 3y in the region on the second electrode 3a side where the second electrode 3a is absent. The first convex portion 2y protrudes from the first electrode 2a. The second convex portion 3y protrudes from the second electrode 3a. The interval between the first convex portion 2y and the second convex portion 3y is narrower than the interval between the first electrode 2a and the second electrode 3a. In the connection structure 1Y, the connection portion 4Y has a solder portion 4YA, a cured portion 4YB, and a spacer 5Y. In the connection structure 1Y, the spacer 5Y is in contact with both the first convex portion 2y and the second convex portion 3y. As a result, the interval between the first electrode 2a and the second electrode 3a is controlled by the spacer 5Y.

From the viewpoint of further improving the conduction reliability, it is preferably the first electrode, When the connecting portion and the second electrode are viewed in the direction of lamination, the opposing portion of the first electrode and the second electrode is disposed, and the solder portion of the connecting portion is disposed opposite to the first electrode and the second electrode. 50% or more of the area is preferably 50% or more (preferably 60% or more, more preferably 70% or more, further preferably 80% or more, and particularly preferably 90% or more).

From the viewpoint of further improving the conduction reliability, it is preferable that the opposing direction of the first electrode and the second electrode is observed in a direction orthogonal to a lamination direction of the first electrode, the connecting portion, and the second electrode. In some cases, 70% or more of the solder portions in the connection portion are disposed in a facing portion of the first electrode and the second electrode.

Next, an example of a method of manufacturing the bonded structure 1 using the conductive paste of one embodiment of the present invention will be described.

First, the first connection target member 2 having the first electrode 2a on the front surface (upper surface) is prepared. Next, as shown in FIG. 2(a), the conductive paste 11 including the thermosetting component 11B, the plurality of solder particles 11A, and the spacer 5 is placed on the surface of the first connection member 2 (first step). The conductive paste 11 is placed on the surface of the first connection member 2 on which the first electrode 2a is provided. After the conductive paste 11 is placed, the solder particles 11A are disposed on both the first electrode 2a (line) and the region (gap) where the first electrode 2a is not formed.

The method of disposing the conductive paste 11 is not particularly limited, and examples thereof include coating by a dispenser, screen printing, and ejection by an inkjet device.

Moreover, the second connection member 3 having the second electrode 3a on the front surface (lower surface) is prepared. Then, as shown in FIG. 2(b), the second connection is placed on the surface of the conductive paste 11 on the side opposite to the first connection target member 2 on the conductive paste 11 on the surface of the first connection member 2. Target member 3 (second step). The second connection member 3 is placed on the surface of the conductive paste 11 from the second electrode 3a side. At this time, the first electrode 2a and the second electrode 3a are opposed to each other.

Next, the conductive paste 11 is heated to a temperature equal to or higher than the melting point of the solder particles 11A and the hardening temperature of the thermosetting component 11B (third step). That is, the conductive paste 11 is heated to a temperature lower than the melting point of the solder particles 11A and the hardening temperature of the thermosetting component 11B. In this At the time of heating, the solder particles 11A existing in the region where the electrode is not formed are aggregated between the first electrode 2a and the second electrode 3a (self-aggregation effect). In the present embodiment, the conductive paste is used instead of the conductive film, and the conductive paste has a specific composition. Therefore, the solder particles 11A are effectively aggregated between the first electrode 2a and the second electrode 3a. Further, the solder particles 11A are melted and joined to each other. Further, the thermosetting component 11B is thermally cured. As a result, as shown in FIG. 2(c), the connection portion 4 that connects the first connection member 2 and the second connection member 3 is formed by the conductive paste 11. The connection portion 4 is formed by the conductive paste 11, and the solder portion 4A is joined by bonding a plurality of solder particles 11A, and the cured portion 4B is formed by thermosetting the thermosetting component 11B. When the solder particles 11A are sufficiently moved, the movement of the solder particles 11A between the first electrode 2a and the second electrode 3a is not completed until the movement of the solder particles 11A between the first electrode 2a and the second electrode 3a is completed. It is also possible not to keep the temperature constant.

In the present embodiment, no pressurization is performed in the second step and the third step. In the present embodiment, the weight of the second connection member 3 is applied to the conductive paste 11. Therefore, at the time of formation of the connection portion 4, the solder particles 11A are effectively aggregated between the first electrode 2a and the second electrode 3a. Further, the connecting portion 4X has a solder portion 4XA, a cured portion 4XB, and a spacer 5. The spacer 5 is easily extruded due to the agglomeration of the solder particles 11A. When the connection portion 4 is formed, the spacer 5 can contact both the first connection target member 2 and the second connection target member 3. Specifically, when the connection portion 4 is formed, the spacer 5 can contact both the first electrode 2a and the second electrode 3a. In addition, when pressurization is performed in at least one of the second step and the third step, the tendency of the solder particles to be agglomerated between the first electrode and the second electrode is suppressed. The inventors have found the above.

In addition, in the present embodiment, when the first connection member to which the conductive paste is applied is superposed on the second connection target member, the electrode of the first connection target member and the second connection target member are not applied. When the first connection target member and the second connection target member are overlapped in the state in which the alignment of the electrodes is shifted, the offset can be corrected, and the electrode of the first connection target member can be connected to the second connection. Electrode connection of the object member (automatic Alignment effect). The reason for this is that the solder which is self-aggregated between the electrode of the first connection member and the electrode of the second connection member is soldered and electrically conductive between the electrode of the first connection member and the electrode of the second connection member. The area in which the other components of the paste contact is the smallest, and the energy is stabilized. Therefore, the connection structure that forms the smallest area, that is, the force of the aligned connection structure functions. At this time, it is preferable that the conductive paste is not cured; and at this temperature and time, the viscosity of the components other than the solder particles of the conductive paste is extremely low.

The spacer exists between the first connection target member and the second connection target member, whereby the distance between the electrode of the first connection target member and the electrode of the second connection target member can be sufficiently ensured. Thereby, the space in which the solder particles are agglomerated can be ensured, and the cohesiveness of the solder particles can be improved. Further, since a sufficient amount of solder can be secured between the electrode of the first connection member and the electrode of the second connection member, it is easy to exhibit automatic alignment even when the electrode is overlapped with respect to the electrode offset. effect. The offset amount of the electrode after the conductive connection is preferably 0 L or more (0 or more), and preferably 0.9 L or less, more preferably 0.75 L or less, when the width of the electrode is L. Further, in the case where the particle diameter of the spacer is set to R, the preferred offset amount X after the electrical connection is preferably 0R or more (0 or more), and preferably 3R or less, more preferably 2R or less. .

The viscosity of the conductive paste at the melting temperature of the solder is preferably 50 Pa s or less, more preferably 10 Pa ‧ or less, further preferably 1 Pa ‧ or less, and preferably 0.1 Pa ‧ or more, more preferably 0.2 Pa‧s or above. When the viscosity is at most the specific viscosity, the solder particles can be efficiently aggregated. If the viscosity is equal to or higher than the specific viscosity, the pores in the joint portion can be suppressed, and the conductive paste can be prevented from overflowing beyond the joint portion.

The connection structure 1 shown in Fig. 1 is obtained in the above manner. Furthermore, the second step and the third step described above may be continuously performed. In addition, after the second step, the obtained third connecting member 2, the conductive paste 11, and the second connecting member 3 may be moved to the heating unit to perform the third step. In order to perform the above heating, the laminated body may be disposed on the heating member, or the laminated body may be disposed in a heated space.

The heating temperature in the third step is not particularly limited as long as it is equal to or higher than the melting point of the solder particles and the curing temperature of the thermosetting component. The heating temperature is preferably 140 ° C or higher, more preferably 160 ° C or higher, and is preferably 450 ° C or lower, more preferably 250 ° C or lower, and still more preferably 200 ° C or lower.

Before the third step, a heating step may be provided in order to homogenize the aggregation of the solder particles before melting. The heating temperature in the heating step is preferably maintained at 5 ° C or higher, more preferably 80 ° C or higher, and preferably 130 ° C or lower, more preferably 120 ° C or lower. Good for 120 seconds or less. In the heating step, the thermosetting component is low in viscosity due to heat, and the solder particles before melting are aggregated to form a network structure, and in the third step, when the solder particles are melted and aggregated, the non-condensation can be reduced. Solder particles.

In the third step, it may preferably be a melting point (° C.) or more of the solder, more preferably a melting point (° C) of the solder + 5° C. or more, and preferably a melting point (° C) of the solder + 20° C. or less. The temperature is raised to the curing temperature of the thermosetting component after the temperature of the melting point of the solder (° C.) + 10 ° C or lower is preferably 10 seconds or longer, preferably 120 seconds or shorter. Thereby, the aggregation of the solder particles can be completed in a state where the viscosity of the thermosetting component before the thermosetting component is cured is low, and further uniform aggregation of the solder particles can be performed.

The temperature increase rate in the third step is preferably 50 ° C / sec or less, more preferably 20 ° C / sec or less, still more preferably 10 ° C / sec or less, and more preferably 10 ° C / sec or less, and more preferably from 30 ° C up to the melting point of the solder particles. Preferably, it is 1 ° C / sec or more, more preferably 5 ° C / sec or more. When the temperature increase rate is equal to or higher than the above lower limit, the aggregation of the solder particles is further uniform. When the temperature increase rate is equal to or lower than the above upper limit, excessive viscosity increase due to progress of curing of the thermosetting component can be suppressed, and it becomes difficult to inhibit aggregation of the solder particles.

Further, after the third step, the first connection member or the second connection member may be peeled off from the connection portion for the purpose of correction of the position or re-operation of the manufacturing. The heating temperature for performing the peeling is preferably at least the melting point of the solder particles, more preferably the melting point of the solder particles. (°C) +10 ° C or more. The heating temperature for performing the peeling may be a melting point (°C) of the solder particles + 100 ° C or less.

The heating method in the third step may be a method in which the entire connection structure is heated to a temperature equal to or higher than the melting point of the solder particles and the curing temperature of the thermosetting component by using a reflow furnace or an oven; or only A method of locally heating the connection portion of the connection structure.

Examples of the apparatus used for the method of locally heating include a hot plate, a hot air gun for supplying hot air, a soldering iron, and an infrared heater.

Further, when the heating plate is partially heated, it is preferable that the surface of the heating plate is formed of a metal having a high thermal conductivity immediately below the connecting portion, and the other heat-dissipating position is formed of a material having a low thermal conductivity such as a fluororesin. Heat the surface of the board.

The first and second connection target members are not particularly limited. Specific examples of the first and second connection target members include semiconductor wafers, semiconductor modules, LED chips, LED components, electronic components such as capacitors and diodes, and resin films, printed boards, and flexible printed boards. Electronic components such as flexible flat cables, rigid flexible substrates, epoxy glass substrates, and glass substrates. The first and second connection target members are preferably electronic components.

It is preferable that at least one of the first connection target member and the second connection target member is a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate. The second connection target member is preferably a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate. The resin film, the flexible printed circuit board, the flexible flat cable, and the rigid flexible substrate have high flexibility and are relatively lightweight. When a conductive film is used for the connection of such a connection target member, there is a tendency that the solder particles are hard to aggregate on the electrode. On the other hand, even if a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate is used, the solder particles can be efficiently aggregated on the electrodes by using the conductive paste, and the conduction reliability between the electrodes can be sufficiently improved. For resin film, flexible printed substrate, soft flat In the case of a cable or a rigid flexible substrate, the effect of improving the conduction reliability between the electrodes which are not pressurized can be more effectively obtained than in the case of using another connection member such as a semiconductor wafer.

Examples of the electrode provided in the connection target member include metal electrodes such as a gold electrode, a nickel electrode, a tin electrode, an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode, a SUS electrode, and a tungsten electrode. In the case where the connection target member is a flexible printed substrate, the electrode is preferably a gold electrode, a nickel electrode, a tin electrode, a silver electrode or a copper electrode. In the case where the connection target member is a glass substrate, the electrode is preferably an aluminum electrode, a copper electrode, a molybdenum electrode, a silver electrode or a tungsten electrode. Further, in the case where the electrode is an aluminum electrode, it may be an electrode formed only of aluminum, or an electrode having an aluminum layer on a surface layer of the metal oxide layer. Examples of the material of 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 element include Sn, Al, Ga, and the like.

Preferably, the first electrode and the second electrode are arranged in a planar structure or in a peripheral structure. When the electrode is placed on the surface in the area array structure or the peripheral structure, the effects of the present invention are further effectively exhibited. The surface array structure is a structure in which electrodes are arranged in a lattice shape on a surface on which electrodes are arranged on a connection target member. The peripheral structure is a structure in which an electrode is disposed on the outer peripheral portion of the connection target member. In the case where the electrodes are arranged in a comb-like structure, the solder particles may be agglomerated along the direction perpendicular to the comb. In contrast, in the above configuration, the solder particles must be made uniform and uniform on the surface on which the electrodes are disposed. Since the amount of solder is easily uneven in the prior method, the method of the present invention further effectively exerts the effects of the present invention.

Hereinafter, the present invention will be specifically described by way of examples and comparative examples. The invention is not limited to the following examples.

Polymer A:

Reactant of bisphenol F with 1,6-hexanediol diglycidyl ether and bisphenol F epoxy resin Synthesis of (Polymer A):

Bisphenol F (containing 4,4'-methylene bisphenol, 2,4'-methylene bisphenol, and 2,2'-methylene bisphenol in a weight ratio of 2:3:1) 100 weight 130 parts by weight of 1,6-hexanediol diglycidyl ether, and 5 parts by weight of a bisphenol F-type epoxy resin ("EPICLON EXA-830CRP" manufactured by DIC Corporation), a resorcinol type epoxy compound ( 10 parts by weight of "EX-201" manufactured by Nagase Kasei Co., Ltd. was placed in a three-necked flask, and the mixture was dissolved at 100 ° C under a nitrogen stream. Thereafter, 0.15 parts by weight of triphenylbutylphosphonium bromide as an addition reaction catalyst of a hydroxyl group and an epoxy group was added, and a polymerization reaction was carried out at 140 ° C for 4 hours under a nitrogen stream to obtain a reactant. (Polymer A).

It was confirmed by NMR (Nuclear magnetic resonance) that the addition polymerization reaction proceeded, and it was confirmed that the reactant (Polymer A) had a hydroxyl group derived from bisphenol F and 1,6-hexanediol condensed water in the main chain. A structural unit in which an epoxy group of a glyceryl ether and a bisphenol F-type epoxy resin is bonded and has an epoxy group at both ends.

The reactant (Polymer A) obtained by GPC had a weight average molecular weight of 28,000 and a number average molecular weight of 8,000.

Polymer B: two-terminal epoxy-based rigid-frame phenoxy resin, "YX6900BH45" manufactured by Mitsubishi Chemical Corporation, weight average molecular weight 16000

Thermosetting compound 1: Resorcinol type epoxy compound, "EX-201" manufactured by Nagase Chemicals Co., Ltd.

Thermosetting compound 2: epoxy compound, "EXA-4850-150" manufactured by DIC Corporation, molecular weight 900, epoxy equivalent 450g/eq

Thermosetting agent 1: Trimethylolpropane tris(3-mercaptopropionate), "TMMP" manufactured by SC Organic Chemical Co., Ltd.

Latent epoxy heat hardener 1: "Fujicure 7000" manufactured by T & K TOKA

Flux 1: glutaric acid, manufactured by Wako Pure Chemical Industries, Inc., melting point (activity temperature) 96 °C

How to make solder particles 1~3:

Solder particles having an anion polymer 1 : 200 g of the solder particle body, 40 g of adipic acid, and 70 g of acetone are weighed into a three-necked flask, and then added as a dehydration condensation contact between a hydroxyl group on the surface of the solder particle body and a carboxyl group of adipic acid 0.3 g of dibutyltin oxide of the medium was reacted at 60 ° C for 4 hours. Thereafter, the solder particles are recovered by filtration.

The collected solder particles, 50 g of adipic acid, 200 g of toluene, and 0.3 g of p-toluenesulfonic acid were weighed into a three-necked flask, and the mixture was evacuated and refluxed, and the reaction was carried out at 120 ° C for 3 hours. At this time, water formed by dehydration condensation was removed and reacted using a Dean-Stark extraction apparatus.

Thereafter, the solder particles were collected by filtration, washed with hexane, and dried. Thereafter, the obtained solder particles were crushed by a ball mill, and then the sieve was selected so as to have a specific CV value.

(ζ potential measurement)

Further, 0.05 g of the solder particles having the anionic polymer 1 was placed in 10 g of methanol, and subjected to ultrasonic treatment, whereby the obtained solder particles were uniformly dispersed to obtain a dispersion. The zeta potential was measured by an electrophoresis method using the dispersion and using "Delsamax PRO" manufactured by Beckman Coulter.

(weight average molecular weight of anionic polymer)

The weight average molecular weight of the anionic polymer 1 on the surface of the solder particles was obtained by dissolving the solder using 0.1 N hydrochloric acid, and recovering the polymer by filtration to obtain GPC.

(CV value of solder particles)

The CV value was measured by a laser diffraction type particle size distribution measuring apparatus ("LA-920" manufactured by Horiba, Ltd.).

Solder particles 1 (SnBi solder particles, melting point 139 ° C, using a solder particle body that has been screened by "ST-3" manufactured by Mitsui Metals Co., Ltd. and having a surface treatment Ion polymer 1 solder particles, average particle size 4 μm, CV value 7%, surface zeta potential: +0.65 mV, polymer molecular weight Mw = 6500)

Solder particles 2 (SnBi solder particles, melting point 139 ° C, solder particles having an anionic polymer 1 using a solder particle body and having been subjected to surface treatment by "DS10" manufactured by Mitsui Metals Co., Ltd., average particle diameter 13 μm, CV Value 20%, surface zeta potential: +0.48mV, polymer molecular weight Mw=7000)

Solder particles 3 (SnBi solder particles, melting point 139 ° C, solder particles having an anionic polymer 1 using a solder particle body which has been subjected to screening of "10-25" manufactured by Mitsui Metals Co., Ltd., having an average particle diameter of 25 μm , CV value 15%, surface zeta potential: +0.4mV, polymer molecular weight Mw = 8000)

Solder particles 4 (SnBi solder particles, melting point 139 ° C, solder particles having an anionic polymer 1 using a solder particle body which has been subjected to screening of "ST-3" manufactured by Mitsui Metals Co., Ltd., having an average particle diameter of 3 μm , CV value of 7%, surface zeta potential: +0.65mV, polymer molecular weight Mw = 6500)

Conductive particle 1: A copper layer having a thickness of 1 μm was formed on the surface of the resin particle, and a conductive layer having a thickness of 3 μm (tin: 铋 = 43% by weight: 57% by weight) was formed on the surface of the copper layer.

Method for producing conductive particles 1:

Nickel-plated benzene resin particles ("Micropcarl SP-210" manufactured by Sekisui Chemical Co., Ltd.) having an average particle diameter of 10 μm were subjected to electroless nickel plating, and a base nickel plating layer having a thickness of 0.1 μm was formed on the surface of the resin particles. Next, the resin particles on which the underlying nickel plating layer was formed were subjected to electrolytic copper plating to form a copper layer having a thickness of 1 μm. Further, electrolytic plating was carried out using an electrolytic plating solution containing tin and antimony to form a solder layer having a thickness of 3 μm. In the above manner, a copper layer having a thickness of 1 μm was formed on the surface of the resin particles, and a conductive layer 1 having a thickness of 3 μm (tin: 铋 = 43% by weight: 57% by weight) was formed on the surface of the copper layer. .

Spacer 1 (average particle size 20 μm, CV value 5%, softening point 330 ° C, manufactured by Sekisui Chemical Co., Ltd., divinylbenzene crosslinked particles, 10% K value 4400 N/mm ² , compression recovery rate 55%)

Spacer 2 (average particle size 30 μm, CV value 5%, softening point 330 ° C, manufactured by Sekisui Chemical Co., Ltd., divinylbenzene crosslinked particles, 10% K value 4200 N/mm ² , compression recovery rate 54%)

Spacer 3 (average particle size 50 μm, CV value 5%, softening point 330 ° C, manufactured by Sekisui Chemical Co., Ltd., divinylbenzene crosslinked particles, 10% K value 4100 N/mm ² , compression recovery rate 54%)

Phenoxy resin ("YP-50S" manufactured by Nippon Steel & Sumitomo Chemical Co., Ltd.)

(Examples 1 to 10)

(1) Production of anisotropic conductive paste

The components shown in the following Table 1 were blended in the amounts shown in Table 1 below to obtain an anisotropic conductive paste.

(2) Production of the first connection structure (L/S = 50 μm / 50 μm)

An epoxy glass substrate (FR-4 substrate) (first connection target member) having a copper electrode pattern (thickness of a copper electrode of 12 μm) having an L/S of 50 μm/50 μm and an electrode length of 3 mm was prepared on the upper surface. In addition, a flexible printed circuit board (second connection target member) having a copper electrode pattern (having a thickness of 12 μm of a copper electrode) having an L/S of 50 μm/50 μm and an electrode length of 3 mm was prepared.

The overlapping area of the epoxy glass substrate and the flexible printed circuit board was set to 1.5 cm × 3 mm, and the number of connected electrodes was set to 75 pairs.

On the upper surface of the above-mentioned epoxy glass substrate, an anisotropic conductive paste immediately after fabrication was applied to the electrode of the epoxy glass substrate by screen printing using a metal mask to form an anisotropy. Conductive paste layer. Next, the flexible printed circuit board is laminated on the upper surface of the anisotropic conductive paste layer so that the electrodes face each other. At this time, no pressurization is performed. The weight of the above flexible printed substrate is applied to the anisotropic conductive paste layer. Thereafter, heating was performed while the temperature of the anisotropic conductive paste layer was 190 ° C. The material was melted, and the anisotropic conductive paste layer was cured at 190 ° C for 10 seconds to obtain a first bonded structure.

(3) Production of the second connection structure (L/S = 75 μm / 75 μm)

An epoxy glass substrate (FR-4 substrate) (first connection target member) having a copper electrode pattern (thickness of a copper electrode of 12 μm) having an L/S of 75 μm/75 μm and an electrode length of 3 mm was prepared on the upper surface. In addition, a flexible printed circuit board (second connection target member) having a copper electrode pattern (thickness of a copper electrode of 12 μm) having an L/S of 75 μm/75 μm and an electrode length of 3 mm was prepared on the lower surface.

The second connection structure was obtained in the same manner as the production of the first connection structure, except that the above-described epoxy glass substrate and the flexible printed circuit board having different L/S were used.

(4) Production of the third connection structure (L/S = 100 μm / 100 μm)

An epoxy glass substrate (FR-4 substrate) (first connection target member) having a copper electrode pattern (thickness of a copper electrode of 12 μm) having an L/S of 100 μm/100 μm and an electrode length of 3 mm was prepared on the upper surface. Further, a flexible printed circuit board (second connection target member) having a copper electrode pattern (having a thickness of 12 μm of a copper electrode) having an L/S of 100 μm/100 μm and an electrode length of 3 mm was prepared on the lower surface.

The third connection structure was obtained in the same manner as the production of the first connection structure except that the epoxy glass substrate and the flexible printed circuit board having different L/S were used.

(Comparative Example 1)

The components shown in the following Table 1 were blended in the amounts shown in Table 1 below to obtain an anisotropic conductive paste. The first, second, and third connection structures were obtained in the same manner as in Example 1 except that the obtained anisotropic conductive paste was used.

(Comparative Example 2)

The components shown in the following Table 1 were blended in the amounts shown in Table 1 below to obtain an anisotropic conductive paste. The first, second, and third connections were obtained in the same manner as in Example 1 except that the obtained anisotropic conductive paste was used and a pressure of 1 MPa was applied during heating. Connect the structure.

(Comparative Example 3)

A phenoxy resin ("YP-50S" manufactured by Nippon Steel & Sumitomo Chemical Co., Ltd.) was dissolved in methyl ethyl ketone (MEK) so as to have a solid content of 50% by weight to obtain a solution. The components other than the phenoxy resin shown in the following Table 1 shown in the following Table 1 were blended with the total amount of the above-mentioned solution, and stirred at 2000 rpm for 5 minutes using a planetary mixer. The bar coater was applied to a release PET (polyethylene terephthalate) film so as to have a thickness of 30 μm after drying. The MEK was removed by vacuum drying at room temperature, whereby an anisotropic conductive film was obtained.

The first, second, and third connection structures were obtained in the same manner as in Example 1 except that the anisotropic conductive film was used.

(Comparative examples 4 and 5)

The components shown in the following Table 1 were blended in the amounts shown in Table 1 below to obtain an anisotropic conductive paste. The first, second, and third connection structures were obtained in the same manner as in Example 1 except that the obtained anisotropic conductive paste was used.

(Evaluation)

(1) Viscosity

The viscosity (η25) of the anisotropic conductive paste at 25 ° C was measured at 25 ° C and 5 rpm using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.).

(2) Thickness of solder portion

The cross section of the obtained connection structure was observed to evaluate the thickness of the solder portion between the electrodes above and below.

(3) Automatic alignment

In the production of the third connection structure, the offset between the electrode of the epoxy glass substrate and the electrode of the flexible printed circuit board is 25 μm (for the fourth connection structure), 50 μm (for the fifth connection structure), 75 μm (for the sixth connection structure) and 90 μm (for the seventh connection structure) Except for this, the fourth to seventh connection structures were obtained in the same manner.

The amount of shift between the electrode of the epoxy glass substrate of the obtained fourth to seventh connection structures and the electrode of the flexible printed circuit board was measured. The 25th to 7th connection structures were produced, and the offset amounts of the upper and lower electrodes were measured for the electrodes at the both ends of the connection structure, and the average value of the measured values was obtained. The automatic alignment was judged by the following criteria.

○○: The average value of the offset is less than 10μm

○: The average value of the offset is 10 μm or more and less than 25 μm.

△: The average value of the offset is 25 μm or more and less than 50 μm.

×: The average value of the offset is 50 μm or more

(4) Configuration accuracy of the solder on the electrode 1

When the opposing portions of the first electrode and the second electrode are observed in the laminated direction of the first electrode, the connecting portion, and the second electrode, the first electrode and the first electrode are connected to the first, second, and third connecting structures. The ratio X of the area of the solder portion disposed in the connection portion in the area of the opposing portion of the second electrode was evaluated as 100%. The arrangement accuracy 1 of the solder on the electrode was determined by the following criteria.

[Criteria for determining the accuracy of the solder on the electrode 1]

○○: The ratio X is 70% or more

○: The ratio X is 60% or more and less than 70%

△: the ratio X is 50% or more and less than 60%

×: The ratio X is less than 50%

(5) Arrangement accuracy of solder on the electrode 2

When the opposing portions of the first electrode and the second electrode are observed in a direction orthogonal to the lamination direction of the first electrode, the connecting portion, and the second electrode, the first, second, and third connecting structures are obtained. The ratio Y of the solder portions disposed in the connection portion between the opposing portions of the first electrode and the second electrode in the solder portion 100% in the connection portion was evaluated. The arrangement accuracy 2 of the solder on the electrode was determined on the basis of the following criteria.

[Criteria for determining the accuracy of solder on the electrode 2]

○○: The ratio Y is 99% or more

○: The ratio Y is 90% or more and less than 99%

△: the ratio Y is 70% or more and less than 90%

×: The ratio Y is less than 70%

(6) Continuity reliability between the upper and lower electrodes

With respect to the obtained first, second, and third connection structures (n = 15), the connection resistance at each connection between the upper and lower electrodes was measured by a four-terminal method. Calculate the average value of the connection resistance. Further, according to the relationship of voltage=current×resistance, the connection resistance can be obtained by measuring the voltage when a constant current flows. The conduction reliability was determined based on the following criteria.

[Determination criteria for continuity reliability]

○○: The average value of the connection resistance is 50mΩ or less

○: The average value of the connection resistance exceeds 50 mΩ and is 70 mΩ or less.

△: The average value of the connection resistance exceeds 70 mΩ and is 100 mΩ or less.

×: The average value of the connection resistance exceeds 100mΩ, or a connection failure occurs.

(7) Insulation reliability between adjacent electrodes

The first, second, and third connection structures (n = 15) obtained were placed in an environment of 85 ° C and a humidity of 85% for 100 hours, and then a voltage of 5 V was applied between the adjacent electrodes, at 25 points. The resistance value was measured. The insulation reliability was determined by the following criteria.

[Determination criteria for insulation reliability]

○○: The average value of the connection resistance is 10 ⁷ Ω or more.

○: The average value of the connection resistance is 10 ⁶ Ω or more and less than 10 ⁷ Ω

△: The average value of the connection resistance is 10 ⁵ Ω or more and less than 10 ⁶ Ω.

×: The average value of the connection resistance is less than 10 ⁵ Ω

(8) Positional shift between the upper and lower electrodes

When the opposing portions of the first electrode and the second electrode are observed in the laminated direction of the first electrode, the connecting portion, and the second electrode, the first electrode is evaluated for the first, second, and third connecting structures obtained. Whether the center line is aligned with the center line of the second electrode, and the distance of the positional offset. The positional shift between the upper and lower electrodes was determined by the following criteria.

[Criteria for determining the positional shift between the upper and lower electrodes]

○○: Position offset is less than 15μm

○: The positional shift is 15 μm or more and less than 25 μm.

△: The positional shift is 25 μm or more and less than 40 μm.

×: The positional shift is 40 μm or more

The details and results are shown in Tables 1 and 2 below.

The same tendency was observed when a resin film, a flexible flat cable, and a rigid flexible substrate were used instead of the flexible printed substrate.

1‧‧‧Connection structure

2‧‧‧1st connection object component

2a‧‧‧1st electrode

3‧‧‧2nd connection object component

3a‧‧‧2nd electrode

4‧‧‧Connecting Department

4A‧‧‧ solder department

4B‧‧‧ Hardened Parts

5‧‧‧ spacers

Claims (15)

A conductive paste for connecting a first connection member having a first electrode on a surface thereof to a second connection member having a second electrode on a surface thereof, and electrically connecting the first electrode and the second electrode; Further, the thermosetting component, the plurality of solder particles, and a plurality of spacers having a melting point of 250 ° C or higher are included, and the average particle diameter of the spacer is larger than the average particle diameter of the solder particles. The conductive paste of claim 1, wherein the spacer is an insulating particle. The conductive paste according to claim 1 or 2, wherein the conductive paste is used to contact the spacer between the first connection target member and the second connection target member. The conductive paste according to claim 1 or 2, wherein the conductive paste is heated to a temperature equal to or higher than a melting point of the solder particles and a hardening temperature of the thermosetting component when the first electrode and the second electrode are electrically connected to each other; A plurality of the above-mentioned solder particles are aggregated and integrated for use. The conductive paste according to claim 1 or 2, wherein a ratio of an average particle diameter of the spacer to an average particle diameter of the solder particles is 1.1 or more and 15 or less. The conductive paste of claim 1 or 2, wherein the content of the spacer is 0.1% by weight or more and 10% by weight or less. The conductive paste according to claim 1 or 2, wherein the solder particles have an average particle diameter of 1 μm or more and 40 μm or less. The conductive paste of claim 1 or 2, wherein the content of the solder particles is 10% by weight or more and 80% by weight or less. The conductive paste according to claim 1 or 2, wherein a ratio of the content of the solder particles in units of % by weight to the content of the spacer in units of % by weight is 2 or more Below 100. A connection structure comprising: a first connection target member having at least one first electrode on a surface thereof; a second connection target member having at least one second electrode on a surface thereof; and a connection portion for the above The connection target member is connected to the second connection target member, and the material of the connection portion is the conductive paste according to any one of claims 1 to 9, wherein the first electrode and the second electrode are in the connection portion. The solder portion is electrically connected, and the spacer is in contact with both the first connection target member and the second connection target member. The connection structure according to claim 10, wherein the second connection target member is a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate. A method of manufacturing a connection structure, comprising the step of disposing the conductive paste on a surface of a first connection member having at least one first electrode on its surface, using the conductive paste according to any one of claims 1 to 9. And a second connection target member having at least one second electrode on the surface of the conductive paste opposite to the first connection target member side, wherein the first electrode and the second electrode are opposed to each other And the step of heating the conductive paste to a temperature equal to or higher than a melting point of the solder particles and a curing temperature of the thermosetting component, thereby forming the first connection member and the second connection member by the conductive paste Connecting the connection portion, and electrically connecting the first electrode and the second electrode by the solder portion in the connection portion, and contacting the spacer with the first connection member and the second connection member The steps of the person. The method of manufacturing the connection structure of claim 12, wherein the first electrode is When the second electrode is electrically connected, the plurality of solder particles are aggregated and integrated by heating to a temperature equal to or higher than a melting point of the solder particles and a curing temperature of the thermosetting component. The method of manufacturing the connection structure according to claim 12 or 13, wherein the step of arranging the second connection member and the step of forming the connection portion are not performed, and the weight of the second connection member is applied to the conductive paste. The method of manufacturing a connection structure according to claim 12 or 13, wherein the second connection target member is a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate.