TW201616519A - Electrically conductive paste, joined structure, and method for manufacturing joined structure - Google Patents

Abstract

Provided is an electrically conductive paste whereby it becomes possible to efficiently arrange solder particles on an electrode, it also becomes possible to prevent the positional displacement between electrodes and it also becomes possible to increase the reliability of electric continuity between electrodes. The electrically conductive paste according to the present invention comprises a heat-curable compound that serves as a heat-curable component, a heat-curing agent and multiple solder particles, wherein the heat-curable compound comprises a crystalline heat-curable compound, and the solder particles are particles in each of which each of the center portion and the electrically conductive outer surface is made from a solder material.

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 anisotropic conductive pastes and anisotropic conductive films are widely known. In the anisotropic conductive material, conductive particles are dispersed in the binder.

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 a 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 glass epoxy substrate (FOB (Film on Board)) Wait.

When the electrode of the flexible printed circuit board and the electrode of the glass epoxy substrate are electrically connected by the anisotropic conductive material, for example, the anisotropic conductive material containing the conductive particles is placed on the glass epoxy substrate. Next, a flexible printed circuit board is laminated and heated and pressurized. 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 anisotropic conductive material, Patent Document 1 discloses a tape including 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. In the above resin layer. The tape is film-like and not paste-like.

Further, Patent Document 1 discloses a method of using the above-described tape. Specifically, the first substrate, the tape, the second substrate, the tape, and the third substrate are sequentially laminated from the bottom to obtain a laminate. At this time, the first electrode provided on the surface of the first substrate is opposed to 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 and then carried out. Thereby, the connection structure is obtained.

Patent Document 2 listed below discloses an anisotropic conductive material in which conductive particles are dispersed in an insulating binder. The lowest melt viscosity [η ₀ ] of the anisotropic conductive material is 1.0 × 10 ² to 1.0 × 10 ⁶ mPa ‧ sec. Regarding the anisotropic conductive material, 1<[η ₁ ]/[η ₀ ]≦3 ([η ₀ ] is the lowest melt viscosity of the anisotropic conductive material, and [η ₁ ] is the lowest melting viscosity. The temperature T _{0 is} lower than the melt viscosity at a temperature T ₁ of 30 ° C).

Further, Patent Document 3 listed below discloses an anisotropic conductive material containing a curable compound, a thermal radical initiator, a photoradical initiator, and conductive particles.

Patent Document 4 listed below discloses an anisotropic conductive material containing conductive particles and a resin component which does not end harden at the melting point of the conductive particles. Specific examples of the conductive particles include tin (Sn), indium (In), bismuth (Bi), silver (Ag), copper (Cu), zinc (Zn), lead (Pb), and cadmium ( Cd), metals such as gallium (Ga), silver (Ag), and thallium (Tl), or alloys of such metals.

Patent Document 4 describes a resin heating step in which the anisotropic conductive resin is heated to a temperature higher than the melting point of the conductive particles and the curing of the resin component is not completed, and a resin component curing step of curing the resin component. Connect the electrodes electrically. Further, Patent Document 1 describes that the temperature distribution shown in FIG. 8 of Patent Document 1 is performed. In Patent Document 1, the conductive particles are melted in the resin component which does not end the curing at the temperature at which the anisotropic conductive resin is heated.

Further, Patent Document 5 listed below discloses a flip chip mounting method in which a half of a plurality of connection terminals are disposed opposite to a wiring substrate having a plurality of electrode terminals. The conductor wafer is electrically connected to the electrode terminal of the wiring substrate and the connection terminal of the semiconductor wafer. The flip chip mounting method includes the steps of: (1) supplying a resin containing solder powder and a convection additive to a surface of the wiring substrate having the electrode terminal; and (2) abutting the semiconductor wafer to the resin surface. And (3) a step of heating the wiring substrate to a temperature at which the solder powder is melted; and (4) a step of curing the resin after the heating step. In the heating step (3) of the wiring board, a connection body electrically connecting the electrode terminal and the connection terminal is formed, and in the resin curing step (4), the semiconductor wafer is fixed to the wiring substrate .

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] WO2008/023452A1

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2009-32657

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2012-186161

[Patent Document 4] Japanese Patent Laid-Open Publication No. 2004-260131

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2006-114865

The tape described in Patent Document 1 has a film shape and is not a paste. Therefore, it is difficult to efficiently distribute the solder on the electrodes (wires). For example, in the tape described in Patent Document 1, it is also easy to arrange one of the solder powders in a region (gap) in which the electrodes are 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, the solder powder or the anisotropic conductive paste containing the conductive particles on the surface of the solder layer may be disposed on the electrode (wire) without being efficiently disposed. In the prior solder powder or conductive particles, there is a case where the moving speed of the solder powder or the conductive particles on the electrode is slow.

Further, the prior anisotropic conductive paste has a positional shift between electrodes which are to be connected above and below.

Further, in Patent Documents 1 and 2, the conductive particles used in the anisotropic conductive material are not specifically described. In the examples of Patent Documents 3 and 5, conductive particles are used in which a copper layer is formed on the surface of the resin particles, and a solder layer is formed on the surface of the copper layer. The central portion of the conductive particles is composed of resin particles. Moreover, even if the anisotropic conductive material described in Patent Documents 1, 2, 3, and 5 is used, the conductive particles are not efficiently disposed on the electrode (line), or between the electrodes to be connected above and below. The situation of positional offset.

In addition, when the anisotropic conductive material described in Patent Document 4 is used and the electrodes are electrically connected by the method described in Patent Document 4, the conductive particles containing the solder are not efficiently disposed on the electrode. The situation on (line). Further, in the embodiment of Patent Document 4, in order to sufficiently move the solder at a temperature equal to or higher than the melting point of the solder, the solder is maintained at a fixed temperature, and the manufacturing efficiency of the bonded structure is lowered. When the temperature distribution is shown in FIG. 8 of Patent Document 4, the manufacturing efficiency of the connection structure is lowered.

An object of the present invention is to provide a conductive paste which can efficiently dispose solder particles on an electrode, prevent positional displacement between electrodes, and improve 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 broad aspect of the present invention, there is provided a conductive paste comprising a thermosetting compound as a thermosetting component, a thermosetting agent, and a plurality of solder particles, wherein the thermosetting compound comprises a crystalline thermosetting compound Further, the solder particles have a center portion and a conductive outer surface which is a solder particle.

In a specific aspect of the conductive paste of the present invention, the crystalline thermosetting compound is a solid at 25 °C.

In a specific aspect of the conductive paste of the present invention, the crystalline thermosetting compound has a melting point of 80 ° C or more and 150 ° C or less.

In a specific aspect of the conductive paste of the present invention, the crystalline thermosetting compound has a molecular weight of 300 or more and 500 or less.

In a specific aspect of the conductive paste of the present invention, the crystalline thermosetting compound is a benzophenone type epoxy compound.

In a specific aspect of the conductive paste of the present invention, the crystal of the above-mentioned crystalline thermosetting compound has an average aspect ratio of 5 or less.

In a specific aspect of the conductive paste of the present invention, the average long diameter of the crystal of the crystalline thermosetting compound is 1/1.5 or less of the average particle diameter of the solder particles.

In a specific aspect of the conductive paste of the present invention, the average long diameter of the crystal of the crystalline thermosetting compound is 1/10 or more of the average particle diameter of the solder particles.

In a specific aspect of the conductive paste of the present invention, the melting point of the crystalline thermosetting compound is lower than the melting point of the solder.

In a specific aspect of the conductive paste of the present invention, the conductive paste contains a flux, and the melting point of the crystalline thermosetting compound is lower than the activation temperature of the flux.

In a specific aspect of the conductive paste of the present invention, the content of the crystalline thermosetting compound is 10% by weight or more based on 100% by weight of the total of the thermosetting compound.

In a specific aspect of the conductive paste of the present invention, the conductive paste contains no filler or contains 5% by weight or less of a filler.

In a specific aspect of the conductive paste of the present invention, in the conductive paste, the crystalline thermosetting compound is dispersed in a particulate form.

In a specific aspect of the conductive paste of the present invention, other thermosetting compounds different from the crystalline thermosetting compound are contained.

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 60 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.

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 on a surface thereof a second electrode; and a connection portion that connects the first connection target member and the second connection target member; the connection portion is a cured product of the conductive paste; and the first electrode and the second electrode are used in the connection portion The solder portion is electrically connected.

According to a broad aspect of the present invention, a method of manufacturing a connection structure is provided, comprising the steps of: arranging the above-mentioned conductive paste on a surface of a first connection member having at least one first electrode on its surface; a conductive paste; a second connection target having at least one of the second electrodes disposed on a surface of the conductive paste opposite to the first connection target member so that the first electrode and the second electrode face each other And the member is connected to the second connection member by the conductive paste formation by 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. The connection portion electrically connects the first electrode and the second electrode by a solder portion in the connection portion.

In a specific aspect of the method for producing a connection structure according to the present invention, in the step of arranging the second connection member and the step of forming the connection portion, the weight of the second connection member is applied to the conductive paste Pressurizing without performing pressurization, or 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 forming the connection portion In both of the steps, the pressure of the pressurization is less than 1 MPa.

In a specific aspect of the manufacturing method of the connection structure of the present invention, in the configuration In the step of forming the second connection member and the step of forming the connection portion, the weight of the second connection target member is applied to the conductive paste without being pressurized.

Preferably, the second connection member is a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate.

In the above-mentioned connection structure, it is preferable that the first electrode and the second electrode face each other along a direction of lamination of the first electrode, the connection portion, and the second electrode, and the first The solder portion in the connection portion is disposed at 50% or more of the area of the portion where the electrode and the second electrode face each other. In the connection structure, it is preferable that when the first electrode and the second electrode face each other in a direction orthogonal to a lamination direction of the first electrode, the connection portion, and the second electrode, 70% or more of the solder portions in the connection portion are disposed in a portion where the first electrode and the second electrode face each other.

The conductive paste of the present invention contains a thermosetting compound as a thermosetting component, a thermosetting agent, and a plurality of solder particles, and the thermosetting compound contains a crystalline thermosetting compound, and the solder particles are central portions and Since the surface other than the conductive surface is a particle of solder, when the electrodes are electrically connected to each other, the solder particles can be efficiently disposed on the electrode, and the positional deviation between the electrodes can be prevented, and the interelectrode can be improved. Conduction reliability.

1‧‧‧Connection structure

1X‧‧‧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

4X‧‧‧Connecting Department

4XA‧‧‧ solder department

4XB‧‧‧ Hardened Parts Department

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.

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

(conductive paste)

The conductive paste of the present invention contains a thermosetting compound as a thermosetting component, a heat curing agent, and a plurality of solder particles. In the conductive paste of the present invention, the thermosetting compound contains a crystalline thermosetting compound. Any of the central portion of the solder particles and the outer surface of the conductive layer are 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.

According to the conductive paste of the present invention, when the electrodes are electrically connected to each other, a plurality of solder particles are likely to be collected between the electrodes facing up and down, and a plurality of solder particles can be efficiently disposed on the electrodes. (on-line. Further, a part of the plurality of solder particles is less likely to be disposed in a region (gap) where the electrode is not formed, and the amount of the solder particles disposed in the region where the electrode is not formed can be made relatively small. Therefore, the conduction reliability between the electrodes can be improved. Further, it is possible to prevent the electrical connection between the electrodes adjacent in the lateral direction which should not be connected, and it is possible to improve the insulation reliability. Further, positional displacement between the electrodes can be prevented. In 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 alignment of the electrode of the first connection target member and the electrode of the second connection target member is shifted. When the first connection target member and the second connection target member are overlapped, the offset can be corrected, and the electrode of the first connection target member and the electrode of the second connection target member can be connected (self-aligned) effect). In order to obtain such an effect, the conductive material is a conductive paste, the conductive particles used together with the thermosetting compound and the thermosetting agent are solder particles, and the thermosetting compound is a crystalline thermosetting compound.

In the case where 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 not used as the solder particles, the conductive particles are less likely to accumulate on the electrodes. Since the conductive particles have low weldability, the conductive particles that have moved to the electrodes easily move outside the electrode. Therefore, the suppression effect of the positional shift between the electrodes is also lowered.

The term "crystallinity" in the crystalline thermosetting compound means a state in which molecular chains are regularly arranged, and the above compound has a glass transition temperature and a melting point.

In the conductive paste of the present invention, it is preferred that the crystal of the above-mentioned crystalline thermosetting compound has an average aspect ratio of 5 or less.

When the anisotropic conductive paste is used after storage, the conductive particles are less likely to be disposed on the electrode (line).

When the average aspect ratio of the crystal of the above-mentioned crystalline thermosetting compound is 5 or less, the storage stability of the conductive paste is excellent. Therefore, in any of the cases before and after storage of the conductive paste, the solder can be efficiently disposed on the electrode, and the conduction reliability between the electrodes can be improved.

When the crystalline thermosetting compound is contained in the conductive paste, when heat is applied to the conductive paste, the viscosity of the conductive paste is sufficiently lowered. When heat is applied to the conductive paste, the crystallinity of the crystalline thermosetting compound is lost, so that the viscosity of the conductive paste is sufficiently lowered to promote the movement of the solder. Further, it has been found that the conductive paste of the crystalline thermosetting compound may have different mobility properties of the solder particles before and after storage of the conductive paste. The reason is considered to be that the crystalline state of the crystalline thermosetting compound changes. In the case where a crystalline thermosetting compound is used, when the average aspect ratio of the crystal of the crystalline thermosetting compound is 5 or less, the movement properties of the solder particles are less likely to change before and after storage of the conductive paste.

Further, in the present invention, the positional deviation between the electrodes can be prevented. In the present invention, when the second connection member is placed on the first connection member in which the conductive paste is disposed on the upper surface, the alignment between the electrode of the first connection member and the electrode of the second connection member is offset. In the case where the first connection target member and the second connection target member overlap each other, the offset can be corrected, and the electrode of the first connection target member and the electrode of the second connection target member can be connected (self-aligned) Quasi-effect). In order to obtain such an effect, the contribution of using a conductive paste having a specific composition is large.

The method of pulverizing the crystalline thermosetting compound is exemplified as a method of setting the average aspect ratio of the crystal of the above-mentioned crystalline thermosetting compound to 5 or less. It is preferred to pulverize the crystalline thermosetting compound and then mix it into the conductive paste. Further, after the crystalline thermosetting compound is screened so that the average aspect ratio is 5 or less, a crystalline thermosetting compound can be used.

In order to further improve the storage stability of the conductive paste, the solder is further efficiently disposed on the electrode, and the positional deviation between the electrodes is further suppressed. The average aspect ratio of the crystal of the crystalline thermosetting compound is preferably 4 the following. The above average aspect ratio is an average of the aspect ratios of the plurality of crystals. The above aspect ratio means long diameter/short diameter. The above aspect ratio is an aspect ratio in the conductive paste.

The average aspect ratio of the crystal of the above crystalline thermosetting compound is 1 or more. The crystal of the above crystalline thermosetting compound is preferably needle crystal. The average aspect ratio of the crystal of the above-mentioned crystalline thermosetting compound is preferably 1.3 in terms of increasing the initial viscosity of the conductive paste, suppressing excessive wetting and diffusion of the conductive paste, and further efficiently disposing the solder on the electrode. More preferably, it is 1.5 or more.

In order to further improve the storage stability of the conductive paste, the solder is further efficiently disposed on the electrode, and the positional deviation between the electrodes is further suppressed. The average long diameter of the crystal of the crystalline thermosetting compound is preferably The average particle diameter of the solder particles is 1/1.5 or less, and more preferably 1/2 or less of the average particle diameter of the solder particles.

The average long diameter of the crystal of the crystalline thermosetting compound is preferably from the viewpoint of increasing the initial viscosity of the conductive paste, suppressing excessive wetting and diffusion of the conductive paste, and further efficiently disposing the solder on the electrode. The average particle diameter of the solder particles is 1/10 or more, and more preferably 1/8 or more of the average particle diameter of the solder particles.

From the viewpoint of further efficiently disposing the solder on the electrode and further suppressing the positional shift between the electrodes, it is preferred that the melting point of the crystalline thermosetting compound is lower than the melting point of the solder. The solder is further efficiently disposed on the electrode, further suppressing The absolute value of the difference between the melting point of the crystalline thermosetting compound and the melting point of the solder is preferably 10 ° C or higher, more preferably 20 ° C or higher, and preferably 80, from the viewpoint of positional displacement between the electrodes. Below °C, more preferably below 70 °C.

In view of further improving the conduction reliability, it is preferred that the conductive paste contains a flux. From the viewpoint of further effectively disposing the solder on the electrode and further suppressing the positional shift between the electrodes, it is preferred that the melting point of the crystalline thermosetting compound is lower than the activation temperature of the flux. The absolute value of the difference between the melting point of the crystalline thermosetting compound and the active temperature of the flux is preferably 5 from the viewpoint of further effectively disposing the solder on the electrode and further suppressing the positional displacement between the electrodes. Above °C, more preferably 10 ° C or more, and preferably 60 ° C or less, more preferably 50 ° C or less.

The present invention can be achieved from the viewpoint of improving both the effect of improving the coating property and the effect of improving the conduction reliability between the electrodes by efficiently moving the conductive particles onto the electrode at a higher level. In the conductive paste, the crystalline thermosetting compound is preferably dispersed in the form of particles.

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 ‧ s or more, and still more preferably 100 Pa ‧ s or more It is preferably 800 Pa‧s or less, more preferably 600 Pa‧s or less, further preferably 500 Pa‧s or less.

The above viscosity (η25) can be appropriately adjusted to 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 suitably used in the following connection structure of the present invention and a method of producing the connection structure.

The above conductive paste is preferably an anisotropic conductive paste. The above conductive paste can be suitably 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 outer surface of the conductive layer. In the above solder particles, either the central portion or the conductive outer surface is formed of solder. The center portion of the solder particle system and the outer surface of the conductive layer are particles of solder.

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

The zeta potential was measured in the following manner.

Determination of zeta potential:

0.05 g of the solder particles was added to 10 g of methanol, and the dispersion was uniformly dispersed by ultrasonic treatment or the like to obtain a dispersion. The dispersion can be used, and the zeta potential can be measured by electrophoresis 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, still more preferably 1 mV or less, further preferably 0.7 mV or less, and particularly preferably 0.5 or less. Below mV. When the zeta potential is less than or equal to the above upper limit, the solder particles are less likely 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 easy to be positive, the solder particles preferably have an anionic polymer which is mainly composed of a solder particle and a surface disposed on the surface of the solder particle body. The solder particles are preferably obtained by surface-treating the solder particle body with a compound which is an anionic polymer or an anionic polymer. The solder particles are preferably a surface treated material formed of a compound which is an anionic polymer or an anionic polymer. The compound which is the above anionic polymer and the above anionic polymer may be used alone or in combination of two or more.

As a method of surface-treating the main body of the solder particle by an anionic polymer, the following method is used, for example, using a (meth)acrylic acid polymer obtained by copolymerizing (meth)acrylic acid, and synthesizing from a dicarboxylic acid and a diol 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 the 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 -), a sulfonate ion group (-SO ₃ ^- ), phosphate ions and group (-PO ₄ ^-) and the like.

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 applied to the solder. Polymerization is carried out on the surface of the particle body. Examples of the functional group that reacts with the hydroxyl group on the surface of the solder particle body 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, an amine group, and Methyl) 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 solder particles can be further provided. Efficiently placed on the electrode.

The above weight average molecular weight means a weight average molecular weight in terms of polystyrene as measured by gel permeation chromatography (GPC, Gel Permeation Chromatography).

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 used to dissolve the solder in the solder particles, and to use a diluted hydrochloric acid or the like which does not cause decomposition of the polymer. After removing the solder particles, the weight average molecular weight of the remaining polymer was measured and determined.

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 means a metal having a melting point of 450 ° C or less. 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, a high-frequency inductively coupled plasma-based spectroscopic spectrometer ("ICP-AES" manufactured by Horiba, Ltd.) or a fluorescent X-ray analyzer ("EDX-800HS" manufactured by Shimadzu Corporation) can be used. ), etc. are measured.

By using the above-described solder particles, the solder is melted and bonded to the electrodes, and the solder portion electrically conducts between the electrodes. For example, since the solder portion and the electrode are easily in surface contact instead of 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, peeling of the solder portion and the electrode is less likely to occur, 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 an alloy containing tin or 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. Among them, the low melting point metal is preferably tin, tin-silver alloy, tin-silver-copper alloy, tin-bismuth alloy, or tin-indium alloy in terms of excellent wettability of the electrode. More preferably tin-bismuth alloy, Tin-indium alloy.

The solder particles are preferably a filler metal based on JIS Z3001: welding term, and having a liquidus of 450 ° C or less. Examples of the composition of the solder particles include a metal composition containing zinc, gold, silver, lead, copper, tin, antimony, indium, or the like. Among them, a tin-indium-based (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 contain nickel, copper, lanthanum, aluminum, zinc, iron, 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, and 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 further It is preferably 75 μm or less, more preferably 60 μm or less, still more preferably 40 μm or less, still more preferably 30 μm or less, further preferably 20 μm or less, particularly 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. The average particle diameter of the solder particles is determined, for example, by observing 50 arbitrary solder particles by an electron microscope or an optical microscope, and calculating an average value or performing a laser diffraction type particle size distribution measurement.

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 is preferably 1% by weight or more, more preferably 2% by weight or more, further preferably 10% by weight or more, and particularly preferably 20% by weight or more, based on 100% by weight of the conductive paste. 30% by weight or more, and 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 can be easily disposed between the electrodes, and the conduction reliability can be further increased. From the viewpoint of further improving the conduction reliability, the content of the above-mentioned solder particles is preferably 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 100% by weight of the conductive paste in terms of further improving the conduction reliability. 20% by weight or more, more preferably 30% by weight or more, and most 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, in terms of further improving the conduction reliability, the content of the solder particles is preferably 100% by weight of the conductive paste. 30% by weight or more, more preferably 40% by weight or more, and still more preferably 70% by weight or less, still 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 100% by weight of the conductive paste in terms of further improving the conduction reliability. 30% by weight or more, more preferably 40% by weight or more, and still more preferably 70% by weight or less, still more preferably 60% by weight or less.

(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. Among them, 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 thermosetting compound contains a crystalline thermosetting compound from the viewpoint of efficiently disposing the solder particles on the electrode, effectively suppressing the positional shift between the electrodes, and improving the conduction reliability between the electrodes and the insulation reliability. . The above-mentioned crystalline thermosetting compound may be used alone or in combination of two or more.

The above-described crystalline thermosetting property is preferable from the viewpoint of more effectively disposing the solder particles on the electrodes, more effectively suppressing the positional shift between the electrodes, and further improving the conduction reliability between the electrodes and the insulation reliability. The compound was a solid at 25 °C.

Further, the solder particles are more efficiently disposed on the electrode, and the positional shift between the electrodes is more effectively suppressed, and the melting point of the crystalline thermosetting compound is further improved from the viewpoint of improving the conduction reliability between the electrodes and the insulation reliability. It is preferably 80 ° C or higher, more preferably 85 ° C or higher, and is preferably 150 ° C or lower, more preferably 140 ° C or lower.

Further, the solder particles are more efficiently disposed on the electrode, the positional shift between the electrodes is more effectively suppressed, and the molecular weight of the crystalline thermosetting compound is further improved from the viewpoint of improving the conduction reliability between the electrodes and the insulation reliability. It is preferably 300 or more, more preferably 350 or more, and is preferably 500 or less, more preferably 400 or less.

When the molecular weight is in the case of the thermosetting compound non-polymer and the structural formula of the thermosetting compound is specified, it means a molecular weight which can be calculated from the structural formula. Further, in the case where the thermosetting compound is a polymer, it means a weight average molecular weight.

Examples of the crystalline thermosetting compound include an epoxy compound and a (meth)acrylic compound.

An aromatic epoxy compound is mentioned as said epoxy compound. Among them, a crystalline epoxy compound such as a resorcinol type epoxy compound, a naphthalene type epoxy compound, a biphenyl type epoxy compound, or a benzophenone type epoxy compound is preferable. More preferably, it is 2,4-bis(glycidoxy)benzophenone or 4,4'-bis(glycidoxy)benzophenone. By using the above-mentioned preferred epoxy compound, the viscosity is high at the stage of bonding the member to be joined, and when the acceleration is applied to the impact such as transportation, the positional deviation between the first connection member and the second connection member can be suppressed. Further, the viscosity of the conductive paste can be greatly reduced by the heat during hardening, and the aggregation of the solder particles can be performed efficiently.

The (meth)acrylic compound is a compound having a (meth)acrylonitrile group. An epoxy (meth) acrylate compound is mentioned as said (meth)acrylic-type compound. A compound obtained by introducing a (meth) acrylonitrile group into an epoxy compound such as (meth)acrylic acid is preferred.

The above-mentioned crystalline thermosetting compound is particularly preferable in that the solder particles are more efficiently disposed on the electrode, the positional shift between the electrodes is more effectively suppressed, and the conduction reliability between the electrodes and the insulation reliability are further improved. The benzophenone type epoxy compound is preferably 2,4-bis(glycidoxy)benzophenone or 4,4'-bis(glycidoxy)benzophenone.

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

The content of the above-mentioned crystalline thermosetting compound is preferably 10% by weight or more, and more preferably 30% by weight or more, based on 100% by weight of all of the thermosetting compound (other thermosetting compound and crystalline thermosetting compound). Further, it is preferably 50% by weight or more, more preferably 70% by weight or more, and still more preferably 100% by weight or less.

(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 cationic curing agent), and a thermal radical. Producing agent, etc. These thermosetting agents may be used alone or in combination of two or more.

Since the conductive paste can be hardened more rapidly at a low temperature, an imidazole hardener, a thiol hardener or an amine hardener is preferred. Moreover, since the storage stability is increased when the thermosetting compound is mixed with the above-mentioned thermosetting agent, a latent curing agent is preferable. 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-all three And 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-all 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-four snail [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. Examples of the ruthenium-based cation hardener include bis(4-t-butylphenyl)phosphonium hexafluorophosphate. Examples of the oxonium-based cation hardener include trimethyloxonium tetrafluoroborate. Examples of the ruthenium-based cation hardener include tri-p-tolylsulfonium hexafluorophosphate.

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) and the like. Examples of the organic peroxide include ditributyl 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 is further 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 above-mentioned thermosetting agent is preferably higher than the melting point of the above solder, more preferably 5 ° C or higher, and further preferably 10 ° C higher, from the viewpoint of further efficiently disposing the solder on the electrode. the above.

The reaction initiation temperature of the above-mentioned thermosetting agent refers to the temperature at which the rise of the heat generation peak in the DSC (Differential Scanning Calorimeter) 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. If the content of the thermosetting agent is at least the above lower limit, it is easy to The conductive paste is sufficiently hardened. When the content of the thermosetting agent is at most the above upper limit, the remaining thermosetting agent that does not participate in hardening after hardening is less likely to remain, and the heat resistance of the cured product is further increased.

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, based on 100 parts by weight of the above-mentioned crystalline thermosetting compound. Hereinafter, it is more preferably 75 parts by weight or less. Further, the content of the thermal curing 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, and more preferably 100%, based on 100 parts by weight of the total of the thermosetting compound. It is preferably 75 parts by weight or less based on the 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 thermosetting agent is at most the above upper limit, the remaining thermosetting agent that does not participate in hardening after hardening is less likely to remain, and the heat resistance of the cured product is further increased.

(flux)

The above conductive paste preferably contains a flux. By using a flux, the solder can be more efficiently disposed on the electrode. The flux is not particularly limited. As the flux, a flux which is usually used for soldering or the like can be used. Examples of the flux include zinc chloride, a mixture of zinc chloride and an inorganic halide, a mixture of zinc chloride and an inorganic acid, a molten salt, a phosphoric acid, a derivative of phosphoric acid, an organic halide, an anthracene, and an organic acid. And turpentine and so on. The flux may be used singly 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 non-activated 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 a rosin. 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 having rosin acid as a main component. The flux is preferably rosin Class, 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 100 ° C or lower, and still more preferably. It is 160 ° C or less, more preferably 150 ° C or less, and still more preferably 140 ° C or less. 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 more effectively exhibited, and the solder is more efficiently disposed on the electrode. The active temperature (melting point) of the above flux is preferably 80 ° C or more and 100 ° C or less. The active temperature (melting point) of the above flux is particularly preferably 80 ° C or more and 140 ° C or less.

Examples of the flux having a living temperature (melting point) of the flux of 80 ° C or more and 100 ° C or less include succinic acid (melting point 186 ° C), glutaric acid (melting point 96 ° C), and adipic acid (melting point 152 ° C). A dicarboxylic acid such as pimelic acid (melting point 104 ° C) or 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.

From the viewpoint of further efficiently disposing the solder on the electrode, the melting point of the flux is preferably higher than the melting point of the solder, more preferably 5 ° C or higher, and still more preferably 10 ° C or 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 high, from the viewpoint of further efficiently disposing the solder on the electrode. Above °C.

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

The above flux is preferably a flux which releases a cation by heating. The solder can be further efficiently disposed on the electrode by using a flux that releases the cation by heating.

The content of the flux is preferably 0.5% by weight in 100% by weight of the conductive paste. The above is preferably 30% by weight or less, more preferably 25% by weight or less. The above conductive paste may also contain no flux. When the content of the flux is not less than the above lower limit and not more than the above upper limit, the oxide film and the surface of the electrode are less likely to form an oxide film, 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, and the material may also be an inorganic filler. By adding a filler, the distance at which the solder particles are agglomerated is suppressed, and the solder particles can be uniformly aggregated on all the electrodes of the substrate.

The conductive paste preferably contains no such filler or contains 5% by weight or less of the above filler. Since a crystalline thermosetting compound is used, the smaller the content of the filler, the easier the solder moves on the electrode.

The content of the filler is preferably 0% by weight or less, more preferably 5% by weight or less, even more preferably 2% by weight or less, still more preferably 1% by weight or less, based on 100% by weight of the conductive paste. . 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 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 of 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 connecting the above 1 is to connect the target member to the second connection target member. In the connection structure of the present invention, the connection portion is formed of the conductive paste and is a cured product of the conductive paste. In the connection structure of the present invention, the first electrode and the second electrode are electrically connected by a solder portion in the connection portion.

The method for producing a connection structure according to the present invention includes the step of: arranging 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; and the conductive paste a second connection target member having at least one second electrode on the surface on the surface opposite to the side of the connection target member such that the first electrode and the second electrode face each other; and heating the conductive paste to When the melting point of the solder particles is equal to or higher than the curing temperature of the thermosetting component, the connection portion connecting the first connection member and the second connection member is formed by the conductive paste, and the solder in the connection portion is used. The first electrode is electrically connected to the second electrode. Preferably, the conductive paste is heated to a temperature higher than a curing temperature of the thermosetting compound.

In the connection structure of the present invention and the method of manufacturing the connection structure of the present invention, since a specific conductive paste is used, a plurality of solder particles are easily collected between the first electrode and the second electrode, and a plurality of solder particles can be used. Efficiently placed on the electrode (line). Further, a part of the plurality of solder particles is less likely to be disposed in a region (gap) where the electrode is not formed, and the amount of the solder particles disposed in the region where the electrode is not formed can be made relatively small. Therefore, the conduction reliability between the first electrode and the second electrode can be improved. Moreover, it is possible to prevent electrical connection between electrodes which are adjacent in the lateral direction which are not connectable, and it is possible to improve insulation reliability.

Further, in order to efficiently arrange a plurality of solder particles on the electrode and to reduce the amount of the solder particles disposed in the region where the electrode is not formed, the inventors have found that it is necessary to use a conductive paste instead of the conductive film.

In the present invention, another method of efficiently concentrating a plurality of solder particles between the electrodes may be further employed. The method of efficiently concentrating a plurality of solder particles between the electrodes is a method of conducting heat by heat when heat is applied to the conductive paste between the first connection member and the second connection member. The viscosity of the paste is lowered, whereby the convection of the conductive paste between the first connection member and the second connection member is generated. Regarding the method, heat capacity of the electrode connected to the surface of the member member and the surface member other than the surface member a method of generating convection by a difference in water, a method of generating convection by forming water of the connection member member into water vapor, and a method of generating convection by a temperature difference between the first connection target member and the second connection target member . Thereby, the solder particles in the conductive paste can be efficiently moved to the surface of the electrode.

In the present invention, a method of selectively condensing solder particles on the surface of the electrode may be employed. As a method of selectively condensing the solder particles on the surface of the electrode, a method of selecting an electrode material having a good wettability of the molten solder particles and a surface having poor wettability of the molten solder particles is selected. The connection target member formed of the material is a method in which solder particles which have been melted on the surface of the electrode are selectively adhered to the electrode, and other solder particles are melted and adhered to the molten solder particles; and an electrode having good thermal conductivity is selected. a method of connecting a member formed by another surface material having a poor material and thermal conductivity to selectively heat the electrode on the electrode by increasing the temperature of the electrode relative to the other surface member when the heat is applied; a solder particle treated by a positive charge on a electrode formed of a metal having a positive charge, a method of selectively condensing solder particles to an electrode; and a conductive paste with respect to an electrode having a hydrophilic metal surface The resin other than the solder particles is made hydrophobic, thereby selectively condensing the solder particles to electricity The method.

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 which the solder is exposed in the area where the electrode is exposed is 100%) is preferably 50% or more, more preferably 60% or more, still more preferably 70% or more, and is preferably 100% or less.

In the method of manufacturing the connection structure of the present invention, preferably, in the step of disposing the second connection member and the step of forming the connection portion, the weight of the second connection member is applied to the conductive paste without performing Pressurizing, or 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 Both In the middle, the pressure of the pressurization is less than 1 MPa. The aggregation of the solder particles can be greatly promoted by applying a pressure of pressurization of 1 MPa or more. In the method of manufacturing the connection structure according to the present invention, in the method of manufacturing the connection structure according to the present invention, at least one of the step of arranging the second connection target member and the step of forming the connection portion is performed. In the step of arranging the second connection member and the step of forming the connection portion, the pressure of the pressurization may be less than 1 MPa. 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 of the steps of forming the above-described connecting portion. When the pressure of the pressurization is less than 1 MPa, the case where the pressurization is not performed is included. 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 more remarkably promoted than when the pressure of the pressurization exceeds 0.8 MPa.

In the method of manufacturing the connection structure of the present invention, preferably, in the step of disposing the second connection member and the step of forming the connection portion, the weight of the second connection member is applied to the conductive paste without performing Preferably, in the step of arranging the second connection member and the step of forming the connection portion, a pressing pressure that does not exceed the weight of the second connection member is applied to the conductive paste. In such cases, the uniformity of the amount of solder can be further improved in a plurality of solder portions. Further, the thickness of the solder portion can be more effectively increased, and a plurality of solder particles can be easily accumulated in a large amount between the electrodes, and a plurality of solder particles can be more efficiently disposed on the electrode (wire). Further, a part of the plurality of solder particles is less likely to be disposed in a region (gap) where 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 the electrodes adjacent in the lateral direction which are not connectable, and it is possible to further improve the insulation reliability.

Further, the inventors have found that the step of arranging the second connection target member In the step of forming the connection portion, the weight of the second connection member is applied to the conductive paste without applying pressure, and the solder particles disposed in a region (gap) where the electrode is not formed before the connection portion is formed are more likely to aggregate. Between the first electrode and the second electrode, a plurality of solder particles can be further efficiently disposed on the electrode (wire). In the present invention, in order to obtain the effect of the present invention at a higher level, a combination of a conductive paste and a conductive film and a weight of the second connection member to be applied to the conductive paste without applying pressure are used. Adoption has great significance.

Further, in WO 2008/023452 A1, it is described that the solder powder is pushed to the surface of the electrode to move it efficiently, and it is possible to pressurize at a specific pressure in the subsequent step, and it is described more reliably. From the viewpoint of forming the solder region, the pressurizing pressure is, for example, 0 MPa or more, preferably 1 MPa or more, and further, the weight of the member placed on the tape may be self-weight even if the pressure applied to the tape is intentionally 0 MPa. Apply a specific pressure to the tape. In WO 2008/023452 A1, it is described that the pressure applied to the tape consciously can be 0 MPa, but the difference in the effect when the pressure exceeding 0 MPa is applied and the case where the pressure is 0 MPa is not described at all. Further, in WO 2008/023452 A1, the importance of using a paste-like conductive paste instead of a film-like conductive paste is also not recognized at all.

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 depending on the amount of the conductive paste applied. On the other hand, regarding the conductive film, in order to change or adjust the thickness of the connection portion, it is necessary to prepare a conductive film having a different thickness or to prepare a conductive film having a specific thickness. Further, in the conductive film, at the melting temperature of the solder, the melt viscosity of the conductive film cannot be sufficiently lowered, and the problem of aggregation of the solder particles is suppressed.

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 object member 2, a second connection object member 3, and a connection portion 4 that connects the first connection object member 2 and the second connection object member 3. connection The portion 4 is formed of the above-mentioned conductive paste. In the present embodiment, a thermosetting compound containing a crystalline thermosetting compound, a thermosetting agent, and a plurality of solder particles are contained. The thermosetting compound and the above-mentioned 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, and a cured portion 4B in which a thermosetting component is thermally cured.

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 front 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 collected 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). Further, in the case of a small amount, solder may be present in a region (a portion of the cured portion 4B) different from the solder portion 4A collected between the first electrode 2a and the second electrode 3a.

As shown in FIG. 1, in the connection structure 1, a plurality of solder particles are collected 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 on the surface of the electrode. After the diffusion, 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 electrode 3a 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 is increased. Therefore, the connection reliability and connection reliability of the connection structure 1 are increased. Further, the conductive paste may also contain a flux. In the case of flux, the flux is usually deactivated by heating.

Further, in the connection structure 1 shown in Fig. 1, all of the solder portions 4A are located in the opposing regions between the first and second electrodes 2a and 3a. The connection structure 1X of the modification shown in FIG. 3 differs from the connection structure 1 shown in FIG. 1 only in the connection portion 4X. Connection portion 4X has welding The material portion 4XA and the cured portion 4XB. As in the connection structure 1X, most of the solder portion 4XA is located in a region facing the first and second electrodes 2a and 3a, and a portion of the solder portion 4XA is opposed to the first and second electrodes 2a and 3a. Extend to the side. The solder portion 4XA that protrudes laterally from the opposing regions of the first and second electrodes 2a and 3a is a portion of the solder portion 4XA, and the solder is separated from the non-solder portion 4XA. Further, in the present embodiment, the amount of solder separated from the solder portion can be reduced, and the solder separated from the solder portion can be present in the cured portion.

When the dose of the solder particles is reduced, the connection structure 1 is easily obtained. When the dose of the solder particles is increased, the connection structure 1X is easily obtained.

In view of further improving the conduction reliability, it is preferable that when the first electrode and the second electrode are opposed to each other along the laminated direction of the first electrode, the connecting portion, and the second electrode, 50% or more (preferably 60% or more, more preferably 70% or more, still more preferably 80% or more, particularly preferably 100% or more of the area of the first electrode and the second electrode facing each other. The solder portion in the above-described connection portion is disposed in 90% or more.

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

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), a conductive paste 11 containing a thermosetting component 11B and a plurality of solder particles 11A 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. Next, as shown in FIG. 2(b), the second paste is placed on the surface of the conductive paste 11 on the side opposite to the first connection 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 lower of the melting point of the solder particles 11A and the hardening temperature of the thermosetting component 11B. At the time of this heating, the solder particles 11A existing in the region where the electrode is not formed are collected between the first electrode 2a and the second electrode 3a (self-condensation effect). In the present embodiment, since the conductive paste is used instead of the conductive film, and the conductive paste has a specific composition, the solder particles 11A are effectively collected 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 target member 2 and the second connection target 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 formed by bonding a plurality of solder particles 11A, and the cured portion 4B is formed by thermally curing 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 may be performed after the movement of the solder particles 11A not between the first electrode 2a and the second electrode 3a is started. Do not keep the temperature fixed until the end.

In the present embodiment, in the second step and the third step, no pressurization is performed. 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 collected between the first electrode 2a and the second electrode 3a. In addition, in at least one of the second step and the third step, when pressurization is performed, the tendency of the solder particles to aggregate between the first electrode and the second electrode is suppressed. This situation was discovered by the inventors.

However, as long as the distance between the first electrode and the second electrode can be ensured, pressurization can be performed. As a method of ensuring the interval between the electrodes, for example, it is necessary to add an electrode equivalent to the desired one. The spacer may be spaced apart from each other, and at least one, preferably three or more spacers may be disposed between the electrodes. Examples of the separator include inorganic particles and organic particles. The spacer is preferably an insulating particle.

Further, in the present embodiment, when the second connection member and the first connection target member coated with the conductive paste are overlapped, the electrode of the first connection target member and the second connection target are not applied. In the state where the alignment of the electrodes of the member is shifted, even when the first connection member and the second connection member overlap, the offset can be corrected, and the electrode of the first connection member and the second The electrode connection (self-alignment effect) of the connected object member. The reason 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 between the electrode of the first connection member and the electrode of the second connection member. When the area in which the components other than the conductive paste are in contact with each other is minimized, the energy is stabilized, and thus the connection structure which is the smallest area, that is, the force of the aligned connection structure acts. In this case, 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 sufficiently low.

The viscosity of the conductive paste at the melting temperature of the solder is preferably 50 Pa ‧ 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 More than ‧s 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 oozing out of 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 can be continuously performed. In addition, after the second step, the obtained first connection member 2 and the laminated body of the conductive paste 11 and the second connection member 3 are moved to the heating unit, and the third step is performed. 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 the heated space.

Furthermore, after the third step described above, in order to correct the position or re-manufacture, The first connection target member or the second connection target member is peeled off from the connection portion. The heating temperature for performing the peeling is preferably not less than the melting point of the solder particles, more preferably the melting point (°C) of the solder particles + 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 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, in order to homogenize the aggregation of the solder particles before melting, a heating step may be provided. The heating temperature in the heating step is preferably maintained at a temperature of preferably 60 ° C or higher, more preferably 80 ° C or higher, and preferably 130 ° C or lower, more preferably 120 ° C or lower. It is preferably 120 seconds or less. In the heating step, the thermosetting component is low in viscosity by heat, and the solder particles before melting are aggregated to form a network structure. When the solder particles are melted and aggregated in the third step, the remaining portion can be reduced. Solder particles.

In the third step, it is preferably at least the melting point (° C.) of the solder, more preferably the melting point (° C) of the solder + 5° C. or higher, and preferably the melting point (° C) of the solder + 20° C. or less. The temperature at which the melting point of the solder (°C) + 10 ° C or less is preferably maintained at 10 seconds or more, preferably 120 seconds or less, and then increased to the hardening temperature of the thermosetting component. 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 the uniform aggregation of the solder particles can be performed.

In the temperature increase rate in the third step, the temperature rise from 30 ° C to the melting point of the solder particles is preferably 50 ° C / sec or less, more preferably 20 ° C / sec or less, further preferably 10 ° C / sec or less, and more preferably It is preferably 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 becomes more uniform. When the temperature increase rate is equal to or lower than the above upper limit, excessive viscosity increase due to hardening of the thermosetting component can be suppressed, and It is easy to suppress the aggregation of solder particles.

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

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 is performed locally by the heating plate, it is preferable that the surface of the heating plate is formed by a metal having a high thermal conductivity immediately below the connecting portion, and the other portion which is not suitable for heating is formed by a material having a low thermal conductivity such as a fluororesin. 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 packages, LED (Light Emitting Diode) wafers, LED packages, electronic components such as capacitors and diodes, and the like. Electronic components such as a resin film, a printed circuit board, a flexible printed circuit board, a flexible flat cable, a rigid flexible substrate, a glass epoxy substrate, and a glass substrate. The first and second connection target members are preferably electronic components.

At least one of the first connection target member and the second connection target member is preferably a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate. Preferably, the second connection member is 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 relatively lightweight properties. When a conductive film is used for the connection of such a connection member, there is a tendency that solder particles are less likely to accumulate 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, it is possible to sufficiently improve the conduction reliability between the electrodes by efficiently concentrating the solder particles on the electrodes. When a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate is used, a case where another connection member such as a semiconductor wafer is used is used. In comparison, it is possible to more effectively obtain an effect of improving the conduction reliability between the electrodes which are not pressurized.

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 an area array or a peripheral type. When the electrodes are arranged on the surface in a region array or in a peripheral manner, the effects of the present invention are more effectively exhibited. The area array is a structure in which electrodes are arranged in a lattice shape on a surface on which an electrode to be connected is placed. The peripheral type is a structure in which electrodes are arranged on the outer circumference of the connection target member. In the case where the electrodes are arranged in a comb shape, the solder particles may be aggregated in a direction perpendicular to the comb. In the above configuration, in the surface on which the electrodes are disposed, the solder particles must be uniformly distributed over the entire surface. Since the amount of solder is likely to be uneven by the conventional method, the effect of the present invention can be more effectively exerted by the method 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:

Bisphenol F (containing 4:3'-methylene bisphenol, 2,4'-methylene bisphenol, and 2,2'-methylene bisphenol in a weight ratio of 2:3:1) 100 Parts by weight, 1,6-hexanediol diglycidyl ether 130 weight 5 parts by weight of bisphenol F type epoxy resin ("EPICLON EXA-830CRP" manufactured by DIC Corporation) and 10 parts by weight of resorcinol type epoxy compound ("EX-201" manufactured by Nagase Chemtex Co., Ltd.) It was added to a 3-neck flask, and it 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 the polymerization reaction was carried out at 140 ° C for 4 hours under a nitrogen stream to obtain a reaction. (Polymer A).

It was confirmed by NMR (Nuclear Magnetic Resonance) that the addition polymerization reaction was carried out, and it was confirmed that the reactant (Polymer A) had a hydroxyl group derived from bisphenol F and 1,6-hexanediol diglycidyl alcohol in the main chain. A structural unit in which an epoxy group of an ether, a bisphenol F type epoxy resin, and a resorcinol type epoxy compound are bonded, and an epoxy group is formed 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: 2,4-bis(glycidoxy)benzophenone (crystalline thermosetting compound, melting point 94 ° C, molecular weight 362)

Synthesis of 2,4-bis(glycidoxy)benzophenone:

To a three-necked flask, 27 g of 2,4-dihydroxybenzophenone, 230 g of epichlorohydrin, 70 g of n-butanol, and 1 g of tetraethylbenzylammonium chloride were added, and the mixture was stirred at room temperature to dissolve. Thereafter, the mixture was heated to 70 ° C under stirring in a nitrogen atmosphere, and 45 g of a sodium hydroxide aqueous solution (concentration: 48% by weight) was added dropwise under reduced pressure. The dropping system was carried out for 4 hours. Thereafter, the Dean-Stark tube was used at 70 ° C to remove water and react for 2 hours. Thereafter, unreacted epichlorohydrin was removed under reduced pressure.

The obtained reaction product was dissolved in 400 g of a mixed solvent of MEK (Methyl Ethyl Ketone, methyl ethyl ketone): n-butanol = 3:1 (weight ratio), and an aqueous sodium hydroxide solution (concentration: 10% by weight) 5 g was added. And heating at 80 ° C for 2 hours.

Thereafter, it was cooled to room temperature and washed with pure water until the washing liquid showed neutrality. After the organic layer was filtered, the fraction was taken, and the residual water and the mixed solvent were removed under reduced pressure to obtain a reaction product.

Using n-hexane, 34 g of the above reaction product was purified by recrystallization, and the residual solvent component was removed by vacuum drying.

The obtained epoxy compound: the melting point measured by DSC was 94 ° C, the epoxy equivalent was 176 g / eq., the molecular weight measured by mass spectrometry was 362, and the melt viscosity at 150 ° C was 5 mPa ‧ s.

‧Differential scanning calorimetry (DSC) measuring device and measuring conditions

Device: "X-DSC7000" manufactured by Hitachi High-Tech Science Co., Ltd., sample amount: 3 mg, temperature condition: 10 ° C / min

Melt viscosity at 150 ° C: measured according to ASTM (American Society for Testing Materials) D4287 using an ICI cone and plate viscometer manufactured by MST Engineering

‧ Determination of epoxy equivalent: measured according to JIS K7236:2001

‧ Determination of molecular weight: Measurement by mass spectrometry GC-MS (Gas Chromatograph Mass Spectrometer) ("JMS K-9" manufactured by JEOL Ltd.)

Thermosetting compound 2: 4,4'-bis(glycidoxy)benzophenone (crystalline thermosetting compound, melting point 132 ° C, molecular weight 362)

Synthesis of 4,4'-bis(glycidoxy)benzophenone:

In a 3-necked flask, 27 g of 4,4'-dihydroxybenzophenone, 230 g of epichlorohydrin, 70 g of n-butanol, and 1 g of tetraethylbenzylammonium chloride were added, and the mixture was stirred at room temperature to dissolve it. . Thereafter, the mixture was heated to 70 ° C under stirring in a nitrogen atmosphere, and 45 g of a sodium hydroxide aqueous solution (concentration: 48% by weight) was added dropwise under reduced pressure. The dropping system was carried out for 4 hours. Thereafter, the Dean-Stark tube was used at 70 ° C to remove water and react for 2 hours. Thereafter, unreacted epichlorohydrin was removed under reduced pressure.

The obtained reaction product was dissolved in 400 g of a mixed solvent of MEK (methyl ethyl ketone): n-butanol = 3:1 (weight ratio), and 5 g of an aqueous sodium hydroxide solution (concentration: 10% by weight) was added thereto, and at 80 g. Heating was carried out for 2 hours at °C.

Thereafter, it was cooled to room temperature and washed with pure water until the washing liquid showed neutrality. After the organic layer was filtered, the fraction was taken, and the residual water and the mixed solvent were removed under reduced pressure to obtain a reaction product.

Using n-hexane, 34 g of the above reaction product was purified by recrystallization, and the residual solvent component was removed by vacuum drying.

The obtained epoxy compound: the melting point measured by DSC was 135 ° C, the epoxy equivalent was 176 g / eq., the molecular weight measured by mass spectrometry was 362, and the melt viscosity at 150 ° C was 12 mPa ‧ s.

Thermosetting compound 3: 1,6-hexanediol diglycidyl ether ("Epogosey HD" manufactured by Yokkaichi Synthetic Co., Ltd., liquid at 25 ° C, molecular weight 230)

Thermosetting compound 4: bisphenol F type epoxy compound, "EXA830CRP" manufactured by DIC Corporation

Thermal hardener 1: pentaerythritol tetrakis(3-mercaptobutyrate), "Karenz MT PE1" manufactured by Showa Denko

Latent epoxy heat hardener 1: "FUJICURE7000" manufactured by T & K TOKA

Flux 1: adipic acid, manufactured by Wako Pure Chemical Industries, Inc., melting point (activity temperature) 152 ° C

How to make solder particles 1~3:

Solder particles having an anionic polymer 1 : 200 g of the solder particle body, 40 g of adipic acid, and 70 g of acetone were placed in a 3-necked flask, followed by dehydration condensation of a hydroxyl group on the surface of the solder particle body with a carboxyl group of adipic acid Catalyst dibutyltin oxide 0.3g, at 60 The reaction was allowed to proceed for 4 hours at °C. Thereafter, the solder particles are collected 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 and placed in a three-necked flask, and the mixture was vacuumed and refluxed, and reacted at 120 ° C for 3 hours. At this time, the water produced by dehydration condensation was removed using a Dean-Stark extraction apparatus, and it was made to react.

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

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

Solder particles 2 (SnBi solder particles, melting point 139 ° C, solder particles having the surface of the solder particles after screening with "DS-10" manufactured by Mitsui Metals Co., Ltd., having an average particle diameter of 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 of the anion polymer 1 having been subjected to surface treatment using "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)

How to make solder particles 4~6:

Solder particles 4:

Weighed SnBi solder particles ("DS-10" manufactured by Mitsui Metals Co., Ltd., average particle diameter (median diameter) 12 μm), 200 g, and a cyanide coupling agent having an isocyanate group ("KBE-9007" manufactured by Shin-Etsu Chemical Co., Ltd.) 10 g And 70 g of acetone were placed in a 3-neck flask. Adding as a reaction between the hydroxyl group and the isocyanate group on the surface of the solder particles while stirring at room temperature The catalyst 0.25 g of dibutyltin laurate was heated under stirring at 60 ° C for 30 minutes under a nitrogen atmosphere. Thereafter, 50 g of methanol was added, and the mixture was heated at 60 ° C for 10 minutes under stirring in a nitrogen atmosphere.

Thereafter, the mixture was cooled to room temperature, and the solder particles were filtered by a filter paper, and desolventized by vacuum drying at room temperature for 1 hour.

The above-mentioned solder particles were placed in a 3-necked flask, and 70 g of acetone, 30 g of monoethyl adipate, and 0.5 g of monobutyltin oxide as a transesterification catalyst were added, and the mixture was stirred under a nitrogen atmosphere at 60 ° C under a nitrogen atmosphere. It was allowed to react for 1 hour.

Thereby, the ester group derived from the decane group of the decane coupling agent and the monoethyl adipate is reacted by a transesterification reaction to carry out covalent bonding.

Thereafter, 10 g of adipic acid was added and reacted at 60 ° C for 1 hour to add adipic acid to the decyl alcohol group of the monoethyl adipate and the unreacted residual ethyl ester group.

Thereafter, the mixture was cooled to room temperature, and the solder particles were filtered by a filter paper, and the solder particles were washed with hexane on the filter paper, thereby leaving unreacted and adhered to the surface of the solder particles by non-covalent bonds. The monoethyl diacid and adipic acid were removed, and then the solvent was removed by vacuum drying at room temperature for 1 hour.

After the obtained solder particles were crushed by a ball mill, the screen was selected in such a manner as to have a specific CV value.

The molecular weight of the polymer formed on the surface of the solder was 0.1% hydrochloric acid, and after dissolving the solder, the polymer was recovered by filtration, and the weight average molecular weight was determined by GPC.

Thereby, the solder particles 4 are obtained. Regarding the obtained solder particles 4, the CV value was 20%, the zeta potential of the surface was 0.9 mV, and the molecular weight of the polymer constituting the surface was Mw = 9,800.

Solder particles 5:

In addition, SnBi solder particles (average particle diameter (median diameter) 30 μm) were used instead of SnBi solder particles ("DS-10" manufactured by Mitsui Metals Co., Ltd., average particle diameter (median diameter) of 12 μm). Solder particles 5 are produced in the same manner as solder particles 4. turn off The solder particles 5 obtained had a CV value of 15%, a zeta potential of 1 mV on the surface, and a molecular weight Mw of the surface constituting the polymer Mw=9900.

Solder particles 6:

In place of SnBi solder particles ("DS-10" manufactured by Mitsui Metals Co., Ltd., average particle diameter (median diameter) 12 μm), SnBi solder particles (manufactured by Mitsui Metals Co., Ltd., average particle diameter (median diameter) 50 μm) were used. Solder particles 6 are produced in the same manner as the solder particles 4. The obtained solder particles 6 had a CV value of 13%, a zeta potential of 1.1 mV on the surface, and a molecular weight Mw of 10,000 constituting the surface.

(ζ potential measurement)

Further, 0.05 g of the solder particles having the anionic polymer 1 was added to 10 g of methanol in the obtained solder particles, and the mixture was uniformly dispersed by ultrasonic treatment to obtain a dispersion. The zeta potential was measured by electrophoresis 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 0.1% hydrochloric acid, and after the solder was dissolved, the polymer was recovered by filtration and determined by 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.).

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:

Electroless nickel plating was performed on divinylbenzene resin particles ("Micropearl SP-210" manufactured by Sekisui Chemical Co., Ltd.) having an average particle diameter of 10 μm, and a nickel-plated nickel layer having a thickness of 0.1 μm was formed on the surface of the resin particles. Then, the resin particles formed with the base nickel plating layer are further Electroplating of copper was performed 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. A copper layer having a thickness of 1 μm was formed on the surface of the resin particles in the above manner, 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. .

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

(Examples 1 to 6, 8 and Comparative Example 2)

(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. Further, in Comparative Example 2, conductive particles in which the center portion was not solder were used.

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

A glass epoxy 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 glass epoxy substrate and the flexible printed substrate was set to 1.5 cm × 3 mm, and the number of connected electrodes was set to 75 pairs.

On the surface of the glass epoxy substrate, a thickness of 100 μm is applied to the electrode of the glass epoxy substrate, and the anisotropic conductive paste immediately after the formation is applied by screen printing using a metal mask. Conductive paste layer to the opposite sex. 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 was performed. The weight of the above flexible printed substrate is applied to the anisotropic conductive paste layer. Then, while the temperature of the anisotropic conductive paste layer was 190 ° C, the solder was melted, and the anisotropic conductive paste layer was cured at 190 ° C for 10 seconds to obtain the first connection structure. .

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

A glass epoxy 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 glass epoxy 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)

A glass epoxy 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 glass epoxy substrate and the flexible printed circuit board having different L/S were used.

(Example 7)

The first, second, and third connection structures were obtained in the same manner as in Example 1 except that a pressure of 1 MPa was applied during the heating of the first conductive paste layer.

(Comparative Example 1)

(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. The first, second, and third connection structures were obtained in the same manner as in Example 1 except that the pressure of 1 MPa was applied to the anisotropic conductive paste obtained.

(Comparative Example 3)

10 parts by weight of a phenoxy resin ("YP-50S" manufactured by Nippon Steel & Sumitomo Chemical Co., Ltd.) was dissolved in methyl ethyl ketone (MEK) so that the solid content was 50% by weight. A solution is obtained. The ingredients other than the phenoxy resin shown in the following Table 1 were blended with the amounts shown in the following Table 1 and the total amount of the above-mentioned solutions, and stirred at 2000 rpm for 5 minutes using a planetary mixer, and then coated with a bar. The cloth machine 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 an anisotropic conductive film was used.

(Examples 9 to 18)

The components shown in the following Tables 3 and 4 were blended in the amounts shown in the following Tables 3 and 4 to obtain an anisotropic conductive paste.

First, the thermosetting compounds 1 and 2 were heated to 140 ° C to be liquidified. It was cooled to 40 ° C and a heat hardener 1 was added. Thereafter, the thermosetting compound 3 which is another thermosetting compound is added, and the mixture is stirred by a planetary mixer until it becomes uniform. Thereafter, the mixture was allowed to stand at 10 ° C for 5 hours to crystallize the thermosetting compounds 1 and 2.

The above-mentioned preparation was kneaded by a three-roll mill until the crystals of the thermosetting compounds 1 and 2 were specific crystal sizes shown in Tables 2 and 3 below.

Further, other formulations were added and stirred by a planetary mixer.

The first, second, and third connection structures were produced in the same manner as in Examples 1 to 6, 8 and Comparative Example 2, using an anisotropic conductive paste before storage. The anisotropic conductive paste was stored at 50 ° C for 12 hours. The first, second, and third connection structures were produced in the same manner as in Examples 1 to 6, 8 and Comparative Example 2, using the anisotropic conductive paste after storage.

(Evaluation)

(0) Average aspect ratio and average long diameter of crystals of crystalline thermosetting compound

The average aspect ratio and the average major axis of the crystal of the crystalline thermosetting compound were evaluated by observing the anisotropic conductive paste before storage with an electron microscope.

(1) Viscosity

The viscosity (η25) of the anisotropic conductive paste before storage at 25 ° C was measured under the conditions of 25 ° C and 5 rpm, 25 ° C and 0.5 rpm using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.).

(2) preservation stability

The anisotropic conductive paste was stored at 50 ° C for 24 hours. The viscosity (η25') of the anisotropic conductive paste after storage at 25 ° C was measured at 25 ° C and 5 rpm using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.). The storage stability was determined by the following criteria.

[Criteria for the determination of preservation stability]

○○: viscosity (η25') / viscosity (η25) is 1 or more and less than 1.2

○: viscosity (η25') / viscosity (η25) is 1.2 or more and less than 1.5

△: viscosity (η25') / viscosity (η25) is 1.5 or more and less than 2

×: viscosity (η25') / viscosity (η25) is 2 or more

(3) Thickness of the solder portion

The thickness of the solder portion between the upper and lower electrodes was evaluated by cross-sectional observation of the first connection structure obtained by using the anisotropic conductive paste before storage.

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

In the first, second, and third connection structures obtained, when the first electrode and the second electrode are opposed to each other in the direction of lamination of the first electrode, the connection portion, and the second electrode, the evaluation is performed. The ratio X of the area of the solder portion is disposed in the connection portion of the area where the one electrode and the second electrode face each other at 100%. The arrangement accuracy 1 of the solder on the electrode was determined by the following reference.

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

○○: 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

In the obtained first, second, and third connection structures, the first electrode and the second electrode are opposed to each other in a direction orthogonal to the lamination direction of the first electrode, the connection portion, and the second electrode. In some cases, the ratio Y of the solder portions in the connection portion of the portion where the first electrode and the second electrode are opposed to each other in the solder portion of the connection portion is evaluated. The arrangement accuracy 2 of the solder on the electrode was determined by the following reference.

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

○○: 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

In 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. Furthermore, the connection resistance can be obtained by measuring the voltage at the time of the current flowing through the relationship of voltage=current×resistance. The conduction reliability was determined by the following criteria.

[Determination of Conductivity 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 electrodes adjacent in the lateral direction

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

[Determination of 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

In the first, second, and third connection structures obtained, when the first electrode and the second electrode are opposed to each other in the direction of lamination of the first electrode, the connection portion, and the second electrode, the evaluation is performed. Whether the center line of the 1 electrode coincides with the center line of the second electrode and the distance of the positional deviation. The positional shift between the upper and lower electrodes is 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 results are shown in Tables 1 to 3 below.

In addition, the average aspect ratio and the average major axis of the crystal of the crystalline thermosetting compound in the anisotropic conductive paste after storage of Examples 9, 10, and 16 were the same as those of the anisotropic conductive paste before storage. The anisotropic conductive paste after storage in Example 9 had a viscosity of 130 mPa·s at 25 ° C and 5 rpm, and a viscosity of 450 mPa ‧ at 25 ° C and 0.5 rpm. The anisotropic conductive paste after storage in Example 10 The viscosity at 25 ° C and 5 rpm is 160 mPa ‧ s, and the viscosity at 25 ° C and 0.5 rpm is 500 mPa ‧ s. The viscosity of the anisotropic conductive paste after storage in Example 16 at 25 ° C and 5 rpm is 350 mPa ‧ s The viscosity at 25 ° C and 0.5 rpm is 1200 mPa ‧ s. In addition, the thickness of the solder portion of the first connection structure obtained by using the anisotropic conductive paste after storage was 33 μm in Example 9, 36 μm in Example 10, and 43 μm in Example 16.

The same tendency can be seen when a resin film, a flexible flat cable, and a rigid flexible substrate are 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

Claims (26)

A conductive paste comprising a thermosetting compound as a thermosetting component, a thermosetting agent, and a plurality of solder particles, wherein the thermosetting compound contains a crystalline thermosetting compound, and the solder particles are central portions and conductivity The outer surface is a particle of solder. The conductive paste of claim 1, wherein the crystalline thermosetting compound is a solid at 25 °C. The conductive paste according to claim 1 or 2, wherein the crystalline thermosetting compound has a melting point of 80 ° C or more and 150 ° C or less. The conductive paste according to claim 1 or 2, wherein the crystalline thermosetting compound has a molecular weight of 300 or more and 500 or less. The conductive paste of claim 1 or 2, wherein the crystalline thermosetting compound is a benzophenone type epoxy compound. The conductive paste of claim 1 or 2, wherein the crystal of the above crystalline thermosetting compound has an average aspect ratio of 5 or less. The conductive paste according to claim 1 or 2, wherein the average long diameter of the crystal of the crystalline thermosetting compound is 1/1.5 or less of the average particle diameter of the solder particles. The conductive paste according to claim 1 or 2, wherein the average long diameter of the crystal of the crystalline thermosetting compound is 1/10 or more of the average particle diameter of the solder particles. The conductive paste of claim 1 or 2, wherein the crystalline thermosetting compound has a melting point lower than a melting point of the solder. The conductive paste of claim 1 or 2, which comprises a flux, and wherein the crystalline thermosetting compound has a melting point lower than an active temperature of the flux. The conductive paste according to claim 1 or 2, wherein the content of the crystalline thermosetting compound is 10% by weight or more based on 100% by weight of the total of the thermosetting compound. The conductive paste of claim 1 or 2 which does not contain a filler or contains less than 5% by weight of a filler. The conductive paste of claim 1 or 2, wherein the crystalline thermosetting compound is dispersed in a particulate form in the conductive paste. The conductive paste of claim 1 or 2, which comprises other thermosetting compound different from the crystalline thermosetting compound. The conductive paste according to claim 1 or 2, wherein the solder particles have an average particle diameter of 1 μm or more and 60 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. 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; the connection portion is a cured product of the conductive paste according to any one of claims 1 to 16, and the first electrode and the second electrode are used in the connection portion. The solder portion is electrically connected. The connection structure according to claim 17, wherein the second connection target member is a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate. The connection structure according to claim 17 or 18, wherein when the first electrode and the second electrode are opposed to each other along the laminated direction of the first electrode, the connecting portion, and the second electrode, The solder in the connection portion is disposed at 50% or more of the area of the portion where the first electrode and the second electrode face each other at 50% or more unit. The connection structure according to claim 17 or 18, wherein the first electrode and the second electrode are opposed to each other in a direction orthogonal to a lamination direction of the first electrode, the connection portion, and the second electrode In some cases, 70% or more of the solder portions in the connection portion are disposed in a portion of the first electrode and the second electrode facing each other. A method of manufacturing a connection structure, comprising the steps of: using the conductive paste according to any one of claims 1 to 16, the conductive paste is disposed on a surface of a first connection member having at least one first electrode on its surface a second connection target member having at least one of the second electrodes 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 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, and forming a connection portion connecting the first connection member and the second connection member with the conductive paste. And electrically connecting the first electrode and the second electrode by a solder portion in the connection portion. The method of manufacturing a connection structure according to claim 21, wherein in the step of arranging the second connection member and the step of forming the connection portion, the weight of the second connection target member is applied to the conductive paste without pressurization And pressing at least one of the step of arranging the second connection target member and the step of forming the connection portion, and the step of arranging the second connection target member and the step of forming the connection portion In the middle, the pressure of the pressurization is less than 1 MPa. The method of manufacturing a connection structure according to claim 22, wherein in the step of arranging the second connection member and the step of forming the connection portion, the weight of the second connection member is applied to the conductive paste without pressurization . The method of manufacturing a connection structure according to any one of claims 21 to 23, wherein the second connection target member is a resin film, a flexible printed circuit board, a flexible flat cable, or a rigid flexible substrate. The method of manufacturing a connection structure according to any one of claims 21 to 23, wherein the connection structure is configured to observe the first layer along a direction of lamination of the first electrode, the connection portion, and the second electrode When the first electrode and the second electrode face each other, the solder portion of the connecting portion is disposed at 50% or more of the area of the portion where the first electrode and the second electrode face each other. The method of manufacturing a connection structure according to any one of claims 21 to 23, wherein a connection structure is obtained which is orthogonal to a laminated direction of the first electrode, the connection portion, and the second electrode When the direction in which the first electrode and the second electrode face each other is observed in the direction, 70% or more of the solder portion in the connection portion is disposed in a portion where the first electrode and the second electrode face each other.