JP2012169263A - Anisotropic conductive material, method for manufacturing connection structure and connection structure - Google Patents

Abstract

An anisotropic conductive material capable of making it difficult for voids to form in a cured layer obtained by curing an anisotropic conductive material.
An anisotropic conductive material according to the present invention includes a thermosetting compound, a thermosetting agent, conductive particles 5, and a filler. The conductive particles 5 have resin particles and a conductive layer disposed on the surface of the resin particles. At least the outer surface layer of the conductive layer is a solder layer. The filler is a nanofiller having an average primary particle diameter of 5 nm or more and 800 nm or less, or a filler having a reactive functional group on the surface. The temperature which shows the minimum melt viscosity in the measurement temperature range 40-300 degreeC of the anisotropic conductive material which concerns on this invention exists in the temperature range of 60-120 degreeC, and this minimum melt viscosity is 1 Pa.s or more.
[Selection] Figure 1

Description

  The present invention relates to an anisotropic conductive material including a plurality of conductive particles, and is used for electrical connection between electrodes of various connection target members such as a flexible printed circuit board, a glass substrate, a glass epoxy substrate, and a semiconductor chip. The present invention relates to an anisotropic conductive material that can be used, a method for manufacturing a connection structure using the anisotropic conductive material, and a connection structure.

  Pasty or film-like anisotropic conductive materials are widely known. In the anisotropic conductive material, a plurality of conductive particles are dispersed in a binder resin.

  Specifically, the anisotropic conductive material includes a connection between the IC chip and the flexible printed circuit board, a connection between the IC chip and the circuit board having the ITO electrode, and a circuit board having the ITO electrode and the flexible printed circuit board. It is used for connection.

  As an example of the anisotropic conductive material, the following Patent Document 1 discloses an anisotropic conductive paste containing an insulating resin and a solder particle component. This anisotropic conductive paste may contain oxide film breaking particles. Here, as the solder particle component, a particle is described in which any one kind of particles selected from the group consisting of solder, resin, ceramic and metal is used as a core and the surface thereof is coated with the solder component. However, in the Example of patent document 1, there is no description about the particle | grains which made resin the nucleus and coat | covered the surface with the solder component as a solder particle component.

  Patent Document 2 below describes anisotropy satisfying the following formulas (A) and (B) when the viscosity at 25 ° C. and 2.5 pm is η1, and the viscosity at 25 ° C. and 20 rpm is η2. A conductive paste is disclosed.

50 Pa · s ≦ η2 ≦ 200 Pa · s Formula (A)
1.5 ≦ η1 / η2 ≦ 4.3 Formula (B)

JP 2006-108523 A JP 2003-064330 A

  For example, when electrically connecting the electrode of a semiconductor chip and the electrode of a glass substrate with a conventional anisotropic conductive material as described in Patent Documents 1 and 2, conductive particles are placed on the glass substrate. An anisotropic conductive material is disposed. Next, the semiconductor chips are stacked, and a thermocompression bonding head is pressed against the upper surface of the semiconductor chip to heat and pressurize. As a result, the anisotropic conductive material is cured, and the electrodes are electrically connected via the conductive particles to obtain a connection structure.

  When the connection structure as described above is manufactured using the conventional anisotropic conductive material described in Patent Documents 1 and 2, for example, when the thermocompression bonding head is pressed against the upper surface of the semiconductor chip, The anisotropic conductive material may be softened by heat, and the anisotropic conductive material may flow and move due to a capillary phenomenon generated between the wirings on the substrate. For this reason, in the obtained connection structure, a void may arise in the hardened | cured material layer which the anisotropic conductive material hardened | cured. If there is a void in the cured product layer, the conduction reliability between the electrodes decreases, or the connection reliability between the connection target member such as a semiconductor chip or a glass substrate and the cured product layer decreases.

  An object of the present invention is to provide an anisotropic conductive material capable of making it difficult for voids to occur in a cured layer obtained by curing an anisotropic conductive material, a method for producing a connection structure using the anisotropic conductive material, and It is to provide a connection structure.

  According to a wide aspect of the present invention, a conductive material comprising a thermosetting compound, a thermosetting agent, conductive particles, and a filler, wherein the conductive particles are disposed on the surfaces of the resin particles and the resin particles. And at least the outer surface layer of the conductive layer is a solder layer, and the filler is a nanofiller having an average primary particle diameter of 5 nm to 800 nm, or a reactive functional layer. A filler having a group on the surface, a temperature indicating a minimum melt viscosity in a measurement temperature range of 40 to 300 ° C. is in a temperature range of 60 to 120 ° C., and the minimum melt viscosity is 1 Pa · s or more An electrically conductive material is provided.

  In a specific aspect of the anisotropic conductive material according to the present invention, the anisotropic conductive material has a viscosity (Pa · s) at a temperature indicating the minimum melt viscosity at a temperature indicating the minimum melt viscosity. The viscosity ratio to the viscosity (Pa · s) at 10 Hz is 3 or more.

  The anisotropic conductive material according to the present invention is preferably an anisotropic conductive paste. The average particle size of the conductive particles is preferably 1 μm or more and 50 μm or less.

  In another specific aspect of the anisotropic conductive material according to the present invention, the thermosetting compound is a thermosetting compound having an epoxy group or a thiirane group, and the filler has a function capable of reacting with the epoxy group or the thiirane group. Has a group.

  In another specific aspect of the anisotropic conductive material according to the present invention, the filler is a nanofiller having an average particle diameter of primary particles of 5 nm or more and 800 nm or less and having a reactive functional group on the surface. .

  The method for manufacturing a connection structure according to the present invention includes a step of disposing an anisotropic conductive material layer using an anisotropic conductive material configured according to the present invention on a first connection target member having an electrode on an upper surface. A step of laminating a second connection target member having an electrode on the lower surface thereof on the upper surface of the anisotropic conductive material layer, and heating and pressurizing the upper surface of the second connection target member, A step of curing the anisotropic conductive material layer by applying heat to the conductive material layer to form a cured product layer.

  In a specific aspect of the method for manufacturing a connection structure according to the present invention, a semiconductor chip is used as the second connection target member.

In another specific aspect of the method for manufacturing a connection structure according to the present invention, as the second connection target member, a second connection target member having an aspect ratio of 5 or more and a plane area of 10 mm ² or more is used. .

  The connection structure according to the present invention includes a first connection target member, a second connection target member, and a cured product layer that electrically connects the first and second connection target members. The cured product layer is formed by curing an anisotropic conductive material configured according to the present invention.

  An anisotropic conductive material according to the present invention includes a thermosetting compound, a thermosetting agent, conductive particles, and a filler. The conductive particles include resin particles and a conductive layer having at least a surface layer as a solder layer. The filler is a nanofiller having an average primary particle size of 5 nm or more and 800 nm or less, or a filler having a reactive functional group on the surface thereof, and the filler according to the present invention. The temperature indicating the minimum melt viscosity in the measurement temperature range of 40 to 300 ° C. of the anisotropic conductive material is in the temperature range of 60 to 120 ° C., and the minimum melt viscosity is 1 Pa · s or more. When a connection object member is connected using an isotropic conductive material, it is possible to make it difficult for voids to occur in the cured product layer obtained by curing the anisotropic conductive material layer.

FIG. 1 is a front sectional view schematically showing a connection structure using an anisotropic conductive material according to an embodiment of the present invention. 2A to 2C are front cross-sectional views for explaining each step of obtaining a connection structure using the anisotropic conductive material according to the embodiment of the present invention. FIG. 3 is a cross-sectional view showing an example of conductive particles used in the anisotropic conductive material according to the present invention. FIG. 4 is a cross-sectional view showing a modified example of the conductive particles shown in FIG.

  Hereinafter, the present invention will be described in detail.

  The anisotropic conductive material according to the present invention includes a thermosetting compound, a thermosetting agent, conductive particles, and a filler. The conductive particles include resin particles and a conductive layer disposed on the surface of the resin particles. At least the outer surface layer of the conductive layer is a solder layer. The filler is a nanofiller having an average primary particle diameter of 5 nm or more and 800 nm or less, or a filler having a reactive functional group on the surface. The temperature indicating the minimum melt viscosity η1 in the measurement temperature range of 40 to 300 ° C. of the anisotropic conductive material according to the present invention is in the temperature range of 60 to 120 ° C., and the minimum melt viscosity η1 is 1 Pa · s or more. .

  The anisotropic conductive material according to the present invention is adopted by adopting the specific composition described above, and further by making the temperature indicating the minimum melt viscosity η1 of the anisotropic conductive material and the value of the minimum melt viscosity η1 satisfy the above relationship. In the connection structure having a cured product layer that is hardened, voids are less likely to occur in the cured product layer. For example, after laminating the second connection target member on the upper surface of the anisotropic conductive material layer disposed on the upper surface of the first connection target member, the upper surface of the second connection target member is heated by a thermocompression bonding head or the like. When pressed, the anisotropic conductive material is softened by heat. At this time, capillarity occurs between the irregularities due to the lead wires of the electrodes arranged on the second connection target member, or in the gaps with different wettability of the softened anisotropic conductive material, but the above relationship is satisfied. Therefore, the flow at the initial stage of heating can be suppressed. As a result, it is difficult for the anisotropic conductive material layer to be pulled in as the second connection target member warps, and the flow and movement of the anisotropic conductive material layer are suppressed. Therefore, voids are less likely to occur in the cured product layer. Here, the lead lines of the electrodes are arranged on the surface layer of the organic substrate so as to face the connection terminals on the semiconductor chip arranged on the surface layer of the organic substrate, for example, when connecting the semiconductor chip and the organic substrate. In other words, the wiring leads out to the outside, and the wiring is arranged substantially perpendicular to the outer periphery of the semiconductor chip. For example, when connecting a glass substrate on which an ITO electrode is formed and a semiconductor chip, a semiconductor chip is provided between the ITO electrodes formed on the surface of the glass substrate, a metal wiring such as aluminum, and a passivation film such as SiN. A gap having a structure that is substantially perpendicular to the outer periphery is formed. Further, for example, in the connection between the flexible substrate and the glass substrate, the wiring disposed on the flexible substrate is disposed substantially perpendicular to the end portion of the application portion of the anisotropic conductive material. Thus, in the case where a gap perpendicular to the outer periphery of the anisotropic conductive material softened by heat is generated, a remarkable effect is obtained in the present invention.

  Also, the conductive particles are conductive particles having resin particles and at least a conductive layer whose surface layer is a solder layer, and the solder particles and the surface layer formed only by the solder are other than the solder layer. Compared to the case where conductive particles are used, high connection reliability can be obtained. In the case of solder particles formed only by solder, when the solder melting point or higher is reached during heating and pressing, the solder particles sandwiched in the space between the electrodes of the first connection target member and the second connection target member are It may melt and protrude from the electrode area. For this reason, a solder may connect between adjacent electrodes, and a short circuit may occur. When the surface layer is other than the solder layer, the electrodes of the first connection target member and the second connection target member are electrically connected only by the contact of the conductive particles. May be necessary, and the process of connecting by high temperature or ultrasonic waves may be complicated. Therefore, the anisotropic conductive material according to the present invention has a great feature in using conductive particles including resin particles and at least a conductive layer whose surface layer is a solder layer.

  Here, the solder includes Sn alloys such as general lead solder and lead-free solder. Sn—In and Sn—Bi systems having a melting point of 80 ° C. or higher and 150 ° C. or lower are preferable. When the melting point is 150 ° C. or lower, the thermosetting compound in the anisotropic conductive material is hard to be cured first, and poor connection is further less likely to occur. When the melting point is 80 ° C. or higher, the solder layer becomes difficult to flow with the flow of the anisotropic conductive material, and a short circuit is further less likely to occur.

  The solder is preferably a low melting point metal (for example, a melting point of 450 ° C. or lower). The low melting point metal is not particularly limited, but is preferably tin or an alloy containing tin. Examples of the alloy include a tin-silver alloy, a tin-copper alloy, a tin-silver-copper alloy, a tin-bismuth alloy, and a tin-zinc alloy. Especially, since the wettability is excellent with respect to each electrode material, the low melting point metal is preferably tin, a tin-silver alloy, or a tin-silver-copper alloy.

  In order to improve the bonding strength between the solder layer (low melting point metal layer) and the electrode, the solder is nickel, copper, antimony, aluminum, zinc, iron, gold, titanium, phosphorus, germanium, tellurium, cobalt, bismuth. Further, it may contain a metal such as manganese, chromium, molybdenum and palladium. Especially, since it is excellent in the effect which improves the joining strength of the said solder layer and an electrode, it is preferable that the said solder contains nickel, copper, antimony, aluminum, and zinc as metals other than a low melting metal.

  The content of the metal other than the low melting point metal contained in 100% by weight of the solder layer is not particularly limited, but is preferably 0.0001% by weight or more, and preferably 1% by weight or less. When the content of the metal other than the low melting point metal is not less than the above lower limit and not more than the above upper limit, the bonding strength between the solder layer and the electrode can be further improved.

  The content of tin contained in 100% by weight of the solder layer is preferably 30% by weight or more. When the content of tin is not less than the above lower limit, the effects of the present invention are effectively exhibited, and mounting defects are more difficult to occur. The tin content in the solder layer means the ratio of tin to the total of elements contained in the solder layer. The tin content in the solder layer is determined using a high-frequency inductively coupled plasma emission spectrometer (“ICP-AES” manufactured by Horiba, Ltd.) or a fluorescent X-ray analyzer (“EDX-800HS” manufactured by Shimadzu). It can be measured.

  From the viewpoint of making it harder to generate voids in the cured product layer, the minimum melt viscosity η1 is 1 Pa · s or more, preferably 10 Pa · s or more. The upper limit of the minimum melt viscosity η1 is not particularly limited, but the minimum melt viscosity η1 is preferably 200,000 Pa · s or less, more preferably 5000 Pa · s or less. If the minimum melt viscosity η1 is less than 1 Pa · s, voids are likely to occur due to the outflow of the resin. When the minimum melt viscosity η1 is not more than the above upper limit, it becomes difficult for the resin to bite between the conductive particles and the electrodes, and poor connection can be prevented more reliably.

  The minimum melt viscosity is determined by measuring the minimum complex viscosity η * using a rheometer. The measurement conditions are strain control 1 rad, frequency 1 Hz, temperature rising rate 20 ° C./min, and measurement temperature range 40 to 300 ° C.

  Examples of the rheometer include STRESTTECH (manufactured by EOLOGICA).

  Viscosity ratio of the anisotropic conductive material according to the present invention to the viscosity η3 (Pa · s) at 10 Hz at the temperature showing the minimum melt viscosity of the viscosity η2 (Pa · s) at 1 Hz at the temperature showing the minimum melt viscosity ( (η2 / η3) is preferably 2 or more, more preferably 3 or more, and still more preferably 4 or more. If the viscosity ratio (η2 / η3) is greater than or equal to the lower limit, voids are less likely to occur in the cured product layer. When the viscosity ratio (η2 / η3) is 3 or more, voids are hardly generated in the cured product layer.

  Furthermore, when the viscosity ratio (η2 / η3) is equal to or higher than the lower limit, the anisotropic conductive material layer can be prevented from unintentionally spreading before or during curing, and contamination in the connection structure is less likely to occur. be able to. Accordingly, when the viscosity ratio (η2 / η3) is equal to or more than the lower limit, it is possible to obtain both effects of suppressing voids in the cured product layer and suppressing contamination due to the flow of the anisotropic conductive material layer. The upper limit of the viscosity ratio (η2 / η3) is not particularly limited, but the viscosity ratio (η2 / η3) is preferably 8 or less.

  The anisotropic conductive material includes a thermosetting compound, a thermosetting agent, conductive particles, and a filler. Hereinafter, the detail of each component contained in the said anisotropic conductive material is demonstrated.

(Thermosetting compound)
Examples of the thermosetting compound include oxetane compounds, epoxy compounds, episulfide compounds, (meth) acrylic compounds, phenolic compounds, amino compounds, unsaturated polyester compounds, polyurethane compounds, silicone compounds, and polyimide compounds. As for the said thermosetting compound, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of easily controlling the curing of the anisotropic conductive material or further improving the conduction reliability of the connection structure, the thermosetting compound is a thermosetting compound having an epoxy group or a thiirane group. It is preferable that The compound having an epoxy group is an epoxy compound. The compound having a thiirane group is an episulfide compound. From the viewpoint of allowing thermosetting to proceed more rapidly, the thermosetting compound is preferably an episulfide compound.

  Since the episulfide compound has a thiirane group instead of an epoxy group, it can be cured quickly at a low temperature. That is, the episulfide compound having a thiirane group can be cured at a lower temperature derived from the thiirane group as compared with the epoxy compound having an epoxy group.

  The epoxy compound and the episulfide compound preferably have an aromatic ring. Examples of the aromatic ring include a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, tetracene ring, chrysene ring, triphenylene ring, tetraphen ring, pyrene ring, pentacene ring, picene ring, and perylene ring. Especially, it is preferable that the said aromatic ring is a benzene ring, a naphthalene ring, or an anthracene ring.

  From the viewpoint of curing more rapidly at a low temperature, the episulfide compound is an episulfide compound having a structure represented by the following formula (1-1), (2-1), (3), (7) or (8). It is preferable that it is an episulfide compound having a structure represented by the following formula (1-1), (2-1) or (3). In the following formula (1-1), the bonding sites of the six groups bonded to the benzene ring are not particularly limited. In the following formula (2-1), the bonding sites of the eight groups bonded to the naphthalene ring are not particularly limited.

  In said formula (1-1), R1 and R2 represent a C1-C5 alkylene group, respectively. Of the four groups R3, R4, R5 and R6, 2 to 4 groups represent hydrogen. The group which is not hydrogen among R3, R4, R5 and R6 represents a group represented by the following formula (4). All four groups of R3, R4, R5 and R6 may be hydrogen. One or two of the four groups of R3, R4, R5 and R6 is a group represented by the following formula (4), and among the four groups of R3, R4, R5 and R6 The group that is not a group represented by the following formula (4) may be hydrogen.

  In said formula (4), R7 represents a C1-C5 alkylene group.

  In said formula (2-1), R51 and R52 represent a C1-C5 alkylene group, respectively. Of the 6 groups of R53, R54, R55, R56, R57 and R58, 4 to 6 groups represent hydrogen. The group which is not hydrogen among R53, R54, R55, R56, R57 and R58 represents a group represented by the following formula (5). All of the six groups of R53, R54, R55, R56, R57 and R58 may be hydrogen. One or two of the six groups of R53, R54, R55, R56, R57 and R58 are groups represented by the following formula (5), and R53, R54, R55, R56, R57 and R58. Of these, a group that is not a group represented by the following formula (5) may be hydrogen.

  In said formula (5), R59 represents a C1-C5 alkylene group.

  In said formula (3), R101 and R102 represent a C1-C5 alkylene group, respectively. Six to eight groups out of the eight groups of R103, R104, R105, R106, R107, R108, R109 and R110 represent hydrogen. The group which is not hydrogen among R103, R104, R105, R106, R107, R108, R109 and R110 represents a group represented by the following formula (6). All of the eight groups of R103, R104, R105, R106, R107, R108, R109 and R110 may be hydrogen. One or two of the eight groups of R103, R104, R105, R106, R107, R108, R109 and R110 are groups represented by the following formula (6), and R103, R104, R105, R106 , R107, R108, R109 and R110, which is not a group represented by the following formula (6), may be hydrogen.

  In said formula (6), R111 represents a C1-C5 alkylene group.

  In said formula (7), R1 and R2 represent a C1-C5 alkylene group, respectively.

  In said formula (8), R3 and R4 represent a C1-C5 alkylene group, respectively.

  The episulfide compound and the episulfide compound having a structure represented by the formulas (1-1) and (2-1) are episulfide compounds having a structure represented by the following formulas (1) and (2). preferable.

  In the above formula (1), R1 to R6 are the same groups as R1 to R6 in the above formula (1-1).

  In the above formula (2), R51 to R58 are the same groups as R51 to R58 in the above formula (2-1).

  The anisotropic conductive material may include a modified phenoxy resin having a thiirane group in which an epoxy group of the phenoxy resin is converted into a thiirane group as an episulfide compound. Using a sulfurizing agent, the epoxy group of the phenoxy resin can be converted to a thiirane group by a conventionally known method.

  The “phenoxy resin” is generally a resin obtained by reacting, for example, an epihalohydrin and a divalent phenol compound, or a resin obtained by reacting a divalent epoxy compound with a divalent phenol compound. .

  In the above reaction for obtaining a phenoxy resin, by using a compound having a thiirane group obtained by converting the epoxy group of the compound having an epoxy group into a thiirane group instead of the compound having an epoxy group as a raw material of the phenoxy resin, The phenoxy resin which has can be obtained. Furthermore, a phenoxy resin having a thiirane group can also be obtained by preparing a phenoxy resin having an epoxy group and converting the epoxy group of the phenoxy resin having an epoxy group into a thiirane group.

  The epoxy compound is not particularly limited. A conventionally well-known epoxy compound can be used as an epoxy compound. As for the said epoxy compound, only 1 type may be used and 2 or more types may be used together.

  Examples of the epoxy compound include phenoxy resin having an epoxy group, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, biphenol type epoxy resin, naphthalene type epoxy resin, fluorene type epoxy resin, phenol aralkyl type epoxy. Examples thereof include a resin, a naphthol aralkyl type epoxy resin, a dicyclopentadiene type epoxy resin, an anthracene type epoxy resin, an epoxy resin having an adamantane skeleton, an epoxy resin having a tricyclodecane skeleton, and an epoxy resin having a triazine nucleus in the skeleton.

  Specific examples of the epoxy compound include, for example, epichlorohydrin and bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol D type epoxy resin and the like, bisphenol type epoxy resin, and epichlorohydrin and phenol novolac or cresol novolak. And epoxy novolac resins derived from Various epoxy compounds having two or more oxirane groups in one molecule such as glycidylamine, glycidyl ester, and alicyclic or heterocyclic may be used.

  Furthermore, as the epoxy compound, for example, a structure in which the thiirane group in the structure represented by the formula (1-1), (2-1), (3), (7) or (8) is replaced with an epoxy group is used. You may use the epoxy compound which has.

  Further, the anisotropic conductive material may be an epoxy compound monomer having a structure represented by the following formula (21), a multimer in which at least two of the epoxy compounds are bonded, or the monomer as an epoxy compound. It may contain a mixture of the body and the multimer.

  In said formula (21), R1 represents a C1-C5 alkylene group, R2 represents a C1-C5 alkylene group, R3 is a hydrogen atom, a C1-C5 alkyl group, or following formula ( 22), R4 represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a structure represented by the following formula (23).

  In said formula (22), R5 represents a C1-C5 alkylene group.

  In said formula (23), R6 represents a C1-C5 alkylene group.

  The epoxy compound having the structure represented by the above formula (21) has an unsaturated double bond and at least two epoxy groups. By using the epoxy compound having the structure represented by the above formula (21), the anisotropic conductive material can be rapidly cured at a lower temperature.

  The anisotropic conductive material is, as an epoxy compound or an episulfide compound, a monomer of a compound having a structure represented by the following formula (31), a multimer in which at least two of the compounds are bonded, or the monomer And a mixture of the multimers.

  In the above formula (31), R1 represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms or a structure represented by the following formula (32), R2 represents an alkylene group having 1 to 5 carbon atoms, and R3 represents carbon. X 1 represents an oxygen atom or a sulfur atom, and X 2 represents an oxygen atom or a sulfur atom.

  In said formula (32), R4 represents a C1-C5 alkylene group, X3 represents an oxygen atom or a sulfur atom.

  The anisotropic conductive paste may contain an epoxy compound having a heterocyclic ring containing a nitrogen atom as an epoxy compound. The epoxy compound having a heterocyclic ring containing a nitrogen atom is preferably an epoxy compound represented by the following formula (41) or an epoxy compound represented by the following formula (42). By using such a compound, the curing rate of the anisotropic conductive material can be further increased, and the heat resistance of the cured product can be further enhanced.

  In said formula (41), R1-R3 represents a C1-C5 alkylene group, respectively, Z represents an epoxy group or a hydroxymethyl group. R1 to R3 may be the same or different.

  In the above formula (42), R1 to R3 each represent an alkylene group having 1 to 5 carbon atoms, p, q and r each represents an integer of 1 to 5, and R4 to R6 each represent an alkylene having 1 to 5 carbon atoms. Represents a group. R1 to R3 may be the same or different. p, q and r may be the same or different. R4-6 may be the same or different.

  The epoxy compound having a heterocyclic ring containing a nitrogen atom is preferably triglycidyl isocyanurate or trishydroxyethyl isocyanurate triglycidyl ether. By using these compounds, the curing rate of the anisotropic conductive material can be further increased.

  The anisotropic conductive material preferably contains an epoxy compound having an aromatic ring as an epoxy compound. By using an epoxy compound having an aromatic ring, the curing rate of the anisotropic conductive material can be further increased and the anisotropic conductive paste can be easily applied. From the viewpoint of further improving the applicability of the anisotropic conductive paste, the aromatic ring is preferably a benzene ring, a naphthalene ring or an anthracene ring. Examples of the epoxy compound having an aromatic ring include resorcinol diglycidyl ether or 1,6-naphthalenediglycidyl ether. Of these, resorcinol diglycidyl ether is particularly preferable. By using resorcinol diglycidyl ether, the curing rate of the anisotropic conductive material can be increased and the paste-like anisotropic conductive paste can be easily applied.

  When a cationic curing agent is used as the thermosetting agent, an alicyclic epoxy compound or an oxetane compound is preferably used.

(Thermosetting agent)
The said thermosetting agent is not specifically limited. A conventionally known thermosetting agent can be used as the thermosetting agent. Examples of the thermosetting agent include imidazole curing agents, amine curing agents, phenol curing agents, polythiol curing agents, acid anhydrides, and cationic curing agents. As for the said thermosetting agent, only 1 type may be used and 2 or more types may be used together.

  Since the anisotropic conductive material can be cured more rapidly at a low temperature, the thermosetting agent is preferably an imidazole curing agent, a polythiol curing agent, or an amine curing agent. In addition, a latent curing agent is preferable because the storage stability of the anisotropic conductive material can be improved. The latent curing agent is preferably a latent imidazole curing agent, a latent polythiol curing agent or a latent amine curing agent. The thermosetting agent may be coated with a polymer material such as polyurethane resin or polyester resin.

  The imidazole curing agent is not particularly limited, and 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2, 4-Diamino-6- [2'-methylimidazolyl- (1 ')]-ethyl-s-triazine and 2,4-diamino-6- [2'-methylimidazolyl- (1')]-ethyl-s- Examples include triazine isocyanuric acid adducts.

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

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

  As the cationic curing agent, an iodonium salt or a sulfonium salt is preferably used. Examples of the cationic curing agent include San-Aid SI-45L, SI-60L, SI-80L, SI-100L, SI-110L, and SI-150L manufactured by Sanshin Chemical Industry Co., Ltd., and Adeka optomer SP manufactured by ADEKA. -150 and SP-170.

Preferred anionic portions of the cationic curing agent include PF ₆ , BF ₄ , and B (C ₆ F ₅ ) ₄ .

  The content of the thermosetting agent is not particularly limited. The content of the thermosetting agent is preferably 5 parts by weight or more, more preferably 10 parts by weight or more, preferably 40 parts by weight or less, more preferably 30 parts by weight or less with respect to 100 parts by weight of the thermosetting compound. More preferably, it is 20 parts by weight or less. When the content of the thermosetting agent is not less than the above lower limit and not more than the above upper limit, the anisotropic conductive material can be sufficiently thermoset. Furthermore, when the content of the thermosetting agent is not less than the above lower limit and not more than the above upper limit, the viscosity ratio (η2 / η3) can be easily made not less than the above lower limit and not more than the above upper limit.

(Filler)
The filler contained in the anisotropic conductive material according to the present invention is a nanofiller having an average primary particle size of 5 nm or more and 800 nm or less, or a filler having a reactive functional group on the surface. . The filler may be a nanofiller having an average primary particle diameter of 5 nm or more and 800 nm or less, or may be a filler having a reactive functional group on the surface. By using such a filler, the temperature showing the minimum melt viscosity η1 can be controlled within the specific range, and the value of the minimum melt viscosity η1 can be controlled to be equal to or higher than the lower limit. Furthermore, the viscosity ratio (η2 / η3) can be controlled to be equal to or higher than the lower limit. The filler is preferably a nanofiller having an average particle diameter of primary particles of 500 nm or more and 800 nm or less and having a reactive functional group on the surface. As for the said filler, only 1 type may be used and 2 or more types may be used together.

  The filler may be an inorganic filler or an organic filler.

  The inorganic filler is not particularly limited, and examples thereof include silica, alumina, aluminum nitride, glass, boron nitride, silicon nitride, silicone, and metal. Examples of the metal include gold, silver, nickel and palladium. Examples of the organic filler include acrylic resin, silicone resin, polyimide, polycarbonate, polytetrafluoroethylene, polyurethane, polystyrene, polyester, ABS resin, and polyacetal resin.

  The shape of the filler is not particularly limited, but is preferably spherical. The filler is preferably a particle.

  The filler preferably has a reactive functional group. By the surface treatment, a filler having a reactive functional group on the surface can be obtained. The reactive functional group is a functional group that can react with the curable compound. Examples of the reactive functional group include an epoxy group, a thiirane group, a hydroxyl group, a thiol group, a carboxyl group, and an alkoxylyl group. Especially, it is preferable that the said thermosetting compound is a thermosetting compound which has an epoxy group or a thiirane group, and the said filler has a functional group which can react with an epoxy group or a thiirane group.

  As the surface treatment agent for introducing the reactive functional group, when the thermosetting compound is the epoxy compound, a silane coupling agent having an epoxy group is preferably used.

  The anisotropic conductive material according to the present invention preferably contains two or more fillers having different degrees of hydrophobicity (M value). Thereby, the oozing of the liquid component from the anisotropic conductive material can be suppressed even on the surface of a substrate or the like having a different polarity.

  When two types of fillers having different degrees of hydrophobicity (M value) are used in combination, the absolute value of the difference in the degree of hydrophobicity (M value) between the two types of fillers is preferably 10 or more, more preferably 20 or more. When the absolute value of the difference between the M values is equal to or more than the above lower limit, it is possible to effectively suppress the generation of voids on both the electrode surface of the adherend having a different polarity and the resin surface around it. The absolute value of the difference between the M values is preferably 60 or less, more preferably 30 or less, and still more preferably 20 or less. When the absolute value of the difference in M values is small, the contact angle between the filler and the molten solder increases, and the solder is easily repelled by the filler existing between the solders in the conductive particles. Thereby, the bridge | bridging between the electroconductive particle which exists between adjacent electrodes can be suppressed, and high anisotropic conductivity can be expressed.

  In addition, in this specification, the hydrophobization degree (M value) of a filler is a value of volume% of methanol in a methanol aqueous solution when the filler begins to wet with the methanol aqueous solution.

  By selecting a suitable minimum melt viscosity η1, minimum melt temperature, and filler, the thermosetting compound can be eliminated before the solder melts, and the filler bites into the contact surface between the electrode and the conductive particles. Is less likely to occur. Thereby, conduction reliability is effectively ensured.

(Conductive particles)
FIG. 3 is a sectional view showing an example of conductive particles used for the anisotropic conductive material.

  The conductive particles 11 include resin particles 12 and a conductive layer 13 disposed on the surface 12 a of the resin particles 12. It is preferable that the surface 12 a of the resin particle 12 is covered with the conductive layer 13. The conductive particles 11 are preferably coated particles. The conductive particles 11 have a conductive layer 13 on the surface 11a.

  The conductive layer 13 includes a first conductive layer 14 covering the surface 12a of the resin particle 12, and a solder layer 15 (second conductive layer) covering the surface 14a of the first conductive layer 14. Have The outer surface layer of the conductive layer 13 is a solder layer 15. Thus, the conductive layer 13 may have a multilayer structure, or may have a multilayer structure of two layers or three or more layers.

  As described above, the conductive layer 13 has a two-layer structure. As in the modification shown in FIG. 4, the conductive particles 21 may have a solder layer 22 as a single conductive layer. The surface layer on the outer side of the conductive layer in the conductive particles may be a solder layer. However, the conductive particles 11 are preferable among the conductive particles 11 and the conductive particles 21 because the production of the conductive particles is easy.

  The method for forming the conductive layer on the surface of the resin particles and the method for forming the solder layer on the surface of the resin particles or on the surface of the conductive layer are not particularly limited. Examples of the method for forming the conductive layer and the solder layer include a method using electroless plating, a method using electroplating, a method using physical collision, a method using physical vapor deposition, and a paste containing metal powder or metal powder and a binder. And a method of coating the surface of the resin particles. Of these, electroless plating or electroplating is preferable. Examples of the method by physical vapor deposition include methods such as vacuum vapor deposition, ion plating, and ion sputtering. Further, in the method based on the physical collision, for example, a theta composer or the like is used.

  The method for forming the solder layer is preferably a physical collision method. The solder layer is preferably formed by physical impact. Further, since the solder layer can be easily formed, the method of forming the solder layer is preferably a method by electroplating or a method of coating metal powder with a theta composer. The solder layer is preferably formed by electroplating or a method of coating metal powder with a theta composer.

  Conventionally, the particle diameter of conductive particles having a solder layer on the outer surface layer of the conductive layer has been about several hundred μm. This is because the solder layer could not be formed uniformly even when trying to obtain conductive particles having a particle size of several tens of μm and having a solder layer on the outer surface layer of the conductive layer. On the other hand, when the solder layer is formed by a method in which metal powder is coated with a theta composer, conductive particles having a particle size of several tens of μm, particularly a particle size of 1 μm or more and 50 μm or less. Even when it is obtained, the solder layer can be uniformly formed on the surface of the resin particles or the surface of the conductive layer.

  The conductive layer other than the solder layer is preferably made of metal. The metal constituting the conductive layer other than the solder layer is not particularly limited. Examples of the metal include gold, silver, copper, platinum, palladium, zinc, lead, aluminum, cobalt, indium, nickel, chromium, titanium, antimony, bismuth, germanium and cadmium, and alloys thereof. In addition, tin-doped indium oxide (ITO) can also be used as the metal. As for the said metal, only 1 type may be used and 2 or more types may be used together.

  The first conductive layer is preferably a nickel layer, a palladium layer, a copper layer, or a gold layer, more preferably a nickel layer, a copper layer, or a gold layer, and even more preferably a copper layer. The conductive particles preferably have a nickel layer, a palladium layer, a copper layer, or a gold layer, more preferably have a nickel layer, a copper layer, or a gold layer, and still more preferably have a copper layer. By using the conductive particles having these preferable conductive layers for the connection between the electrodes, the connection resistance between the electrodes can be further reduced. In addition, a solder layer can be more easily formed on the surface of these preferable conductive layers. Note that the first conductive layer 14 may be a solder layer. The conductive particles may have a plurality of solder layers.

  The thickness of the solder layer is preferably 0.5 μm or more, more preferably 2 μm or more, further preferably 4 μm or more, preferably 20 μm or less, more preferably 10 μm or less. When the thickness of the solder layer is not less than the above lower limit, the conductivity is sufficiently high. When the thickness of the solder layer is not more than the above upper limit, the difference in thermal expansion coefficient between the resin particles and the solder layer becomes small, and the solder layer is hardly peeled off.

  When the conductive layer has a multilayer structure, the thickness of the conductive layer other than the solder layer is preferably 10 nm or more, more preferably 100 nm or more, still more preferably 1000 nm or more, preferably 20 μm or less, more preferably 10 μm or less, Preferably it is 5 micrometers or less, Most preferably, it is 3 micrometers or less.

  Examples of the resin for forming the resin particles include polyolefin resin, acrylic resin, phenol resin, melamine resin, benzoguanamine resin, urea resin, epoxy resin, unsaturated polyester resin, saturated polyester resin, polyethylene terephthalate, polysulfone, and polyphenylene. Examples thereof include oxide, polyacetal, polyimide, polyamideimide, polyetheretherketone, polyethersulfone, divinylbenzene polymer and divinylbenzene copolymer. Examples of the divinylbenzene copolymer include divinylbenzene-styrene copolymer and divinylbenzene- (meth) acrylic acid ester copolymer. Since the hardness of the resin particles can be easily controlled within a suitable range, the resin for forming the resin particles is a polymer obtained by polymerizing one or more polymerizable monomers having an ethylenically unsaturated group. Preferably there is.

  The 10% K value (compression elastic modulus) of the resin particles in the conductive particles is preferably 1000 MPa or more, and preferably 15000 MPa or less. If the 10% K value is less than 1000 MPa, the resin particles may be destroyed when the resin particles are compressed and deformed. When the 10% K value exceeds 15000 MPa, the conductive particles may damage the electrode. The 10% K value is more preferably 2000 MPa or more, and more preferably 10,000 MPa or less.

  The 10% K value is obtained by using a micro compression tester (for example, “PCT-200” manufactured by Shimadzu Corporation) and using a smooth indenter end face of a diamond cylinder having a diameter of 50 μm and a compression speed of 2.6 mN / The compression displacement (mm) when compressed under conditions of seconds and a maximum test load of 10 g can be measured and determined by the following equation.

K value ^{(N / mm 2) = (} 3 / √2) · F · S -3/2 · R -1/2
F: Load value (N) in 10% compression deformation of resin particles
S: Compression displacement (mm) in 10% compression deformation of resin particles
R: radius of resin particles (mm)

  When the amount of compressive deformation is 20%, the 20% K value of the resin particles in the conductive particles is preferably 700 MPa or more, more preferably 10,000 MPa or more, preferably 10,000 MPa or less, more preferably 6000 MPa or less.

  The compression deformation recovery rate of the resin particles in the conductive particles is preferably 30% or more, more preferably 40% or more. If the compression deformation recovery rate is too low, the resin particles may not sufficiently recover to the shape before deformation after the compression load is removed. For this reason, when the electrodes are connected, a slight gap is formed between the electrodes and the conductive particles, which may cause poor electrical connection between the electrodes or increase the connection resistance between the electrodes. Tend to.

  The compression deformation recovery rate can be obtained as follows.

  Using a micro-compression tester (“PCT-200” manufactured by Shimadzu Corporation), from the load value for the origin (0.4 mN) to the reverse compression load value of 10 mN, at a load load speed of 0.3 mN / sec. A load is applied to the resin particles by a smooth end face (50 μm × 50 μm) of a square prism made of diamond. After reaching the reverse compression load value of 10 mN, the compression state is maintained for 60 seconds. Thereafter, the load on the resin particles is released at a load unloading speed of 0.3 mN / sec until the load value for origin (0.4 mN) is reached. The compression displacement at this time is measured, and the compression deformation recovery rate can be obtained from the obtained measurement value according to the following equation.

Compression deformation recovery rate (%) = [(L1-L2) / L1] × 100
L1: Compressive displacement (mm) from the origin load value when applying load to the reverse compression load value
L2: Compression displacement (mm) from the reverse compression load value to the load value for origin when releasing the load

  The average particle diameter of the conductive particles is preferably 1 μm or more, more preferably 5 μm or more, preferably 100 μm or less, more preferably 80 μm or less, still more preferably 50 μm or less, particularly preferably 40 μm or less, and most preferably 30 μm or less. . When the average particle diameter of the conductive particles is not less than the above lower limit and not more than the above upper limit, the contact area between the conductive particles and the electrode can be sufficiently increased, and the conductive particles aggregated when forming the conductive layer. Is difficult to form. Further, the distance between the electrodes connected via the conductive particles does not become too large, and the conductive layer is difficult to peel from the surface of the resin particles.

  Since the size is suitable for the conductive particles in the anisotropic conductive material and the distance between the electrodes can be further reduced, the average particle diameter of the conductive particles is 1 μm or more and 50 μm or less. Particularly preferred.

  From the viewpoint of making it more difficult to generate voids in the cured product layer in the connection structure, the average particle size of the conductive particles is preferably 5 μm or more, and preferably 30 μm or less.

  The “average particle diameter” of the conductive particles indicates the number average particle diameter. The average particle diameter of the conductive particles can be obtained by observing 50 arbitrary conductive particles with an electron microscope or an optical microscope and calculating an average value.

  The content of the conductive particles is not particularly limited. In 100% by weight of the anisotropic conductive material, the content of the conductive particles is preferably 0.1% by weight or more, more preferably 0.5% by weight or more, preferably 20% by weight or less, more preferably 15% by weight. % Or less. A conductive particle can be easily arrange | positioned between the upper and lower electrodes which should be connected as content of the said electroconductive particle is more than the said minimum and below the said upper limit. Furthermore, it becomes difficult to electrically connect adjacent electrodes that should not be connected via a plurality of conductive particles. That is, a short circuit between adjacent electrodes can be further prevented.

  The 10% K value of the conductive particles is preferably 3000 MPa or more, and preferably 70000 MPa or less. When the 10% K value is less than 3000 MPa, the resin particles are broken between the electrodes of the first connection target member and the second connection target member, and the solder powder flows out between adjacent electrodes to cause a short circuit. Sometimes. When the 10% K value exceeds 70000 MPa, the conductive particles may damage the electrode. The 10% K value is more preferably 5000 MPa or more, and more preferably 50000 MPa or less.

  The surface of the conductive particles may be coated with an insulating layer as necessary, and insulating particles smaller than the conductive particles may be attached to the surface of the conductive particles.

(flux)
The anisotropic conductive material according to the present invention preferably contains a flux. The flux is not particularly limited. As the flux, a flux generally 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, phosphoric acid, a derivative of phosphoric acid, an organic halide, hydrazine, an organic acid, and pine resin. Is mentioned. Only 1 type of flux may be used and 2 or more types may be used together.

  Examples of the molten salt include ammonium chloride. Examples of the organic acid include lactic acid, citric acid, stearic acid, glutamic acid, glutaric acid, and hydrazine. Examples of the pine resin include activated pine resin and non-activated pine resin. The flux is preferably an organic acid having two or more carboxyl groups, pine resin. The flux may be an organic acid having two or more carboxyl groups, or pine resin. By using an organic acid having two or more carboxyl groups, pine resin, the connection resistance between the electrodes can be lowered.

  The rosin is a rosin composed mainly of abietic acid. The flux is preferably rosins, and more preferably abietic acid. By using this preferable flux, the connection resistance between the electrodes can be further reduced.

  The flux may be dispersed in the anisotropic conductive material or may be adhered on the surface of the conductive particles.

  The anisotropic conductive material according to the present invention may contain a basic organic compound in order to adjust the activity of the flux. Examples of the basic organic compound include aniline hydrochloride and hydrazine hydrochloride.

  In 100% by weight of the anisotropic conductive material, the content of the flux is 0% by weight or more, preferably 0.5% by weight or more, preferably 30% by weight or less, more preferably 25% by weight or less. The anisotropic conductive material may not contain a flux. When the flux content is not less than the above lower limit and not more than the above upper limit, an oxide film is more difficult to be formed on the surface of the solder layer, and the oxide film formed on the solder layer or the electrode surface is more effective. Can be removed.

(Other ingredients)
The anisotropic conductive material preferably further contains a curing accelerator. By using a curing accelerator, the curing rate can be further increased. As for a hardening accelerator, only 1 type may be used and 2 or more types may be used together.

  Specific examples of the curing accelerator include imidazole curing accelerators and amine curing accelerators. Of these, imidazole curing accelerators are preferred. In addition, an imidazole hardening accelerator or an amine hardening accelerator can be used also as an imidazole hardening agent or an amine hardening agent.

  Examples of the imidazole curing accelerator include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino- 6- [2′-Methylimidazolyl- (1 ′)]-ethyl-s-triazine and 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine isocyanuric acid addition Thing etc. are mentioned.

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

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

  The content of the curing accelerator is preferably 0.5 parts by weight or more, more preferably 1 part by weight or more, preferably 6 parts by weight or less, more preferably 4 parts by weight with respect to 100 parts by weight of the thermosetting compound. Or less. When the content of the curing accelerator is not less than the above lower limit, it is easy to sufficiently cure the anisotropic conductive material. When the content of the curing accelerator is less than or equal to the above upper limit, it is difficult for an excessive curing accelerator that did not participate in curing after curing to remain.

  It is preferable that the anisotropic conductive material further includes a phenolic compound together with the episulfide compound. The combined use of the episulfide compound, the thermosetting agent, and the phenolic compound makes it more difficult for the thiirane group to open during storage of the anisotropic conductive material. Moreover, when an anisotropic conductive material is arrange | positioned between electrodes and an electroconductive particle is compressed appropriately, an appropriate indentation can be formed in an electrode. Therefore, the connection resistance between the electrodes can be lowered.

  The phenolic compound has a phenolic hydroxyl group in which a hydroxyl group is bonded to a benzene ring. Examples of the phenolic compound include polyphenol, triol, hydroquinone, and tocopherol (vitamin E). As for the said phenolic compound, only 1 type may be used and 2 or more types may be used together.

  The anisotropic conductive material may contain a solvent. By using the solvent, the viscosity of the anisotropic conductive material can be easily adjusted. Examples of the solvent include ethyl acetate, methyl cellosolve, toluene, acetone, methyl ethyl ketone, cyclohexane, n-hexane, tetrahydrofuran, and diethyl ether.

  The anisotropic conductive material preferably contains a storage stabilizer. The anisotropic conductive material preferably contains at least one selected from the group consisting of phosphate ester, phosphite ester and borate ester as the storage stabilizer. It is more preferable that at least one of them is included, and it is even more preferable that a phosphite is included. By using these storage stabilizers, particularly by using phosphites, the storage stability of the episulfide compound can be further enhanced. As for the said storage stabilizer, only 1 type may be used and 2 or more types may be used together.

  The anisotropic conductive material includes at least one component selected from the group consisting of ascorbic acid, ascorbic acid derivatives, ascorbic acid salts, isoascorbic acid, isoascorbic acid derivatives, and isoascorbic acid salts. You may go out. By blending these components, the storage stability of the anisotropic conductive material is increased.

  The anisotropic conductive material may further contain an ion scavenger or a silane coupling agent as necessary.

  In addition, the anisotropic conductive material may contain a photocurable compound and a photopolymerization initiator so that the anisotropic conductive material can be cured by light irradiation. In the case of a two-step reaction in which the resin is semi-cured by light irradiation and then fully cured by heat, the anisotropic conductive material can shorten the reaction time during the main curing. The photocurable compound preferably has a functional group that can be cured by light and heat. For example, using a compound having a thermosetting functional group such as an epoxy group or a thiirane group and a photocurable functional group such as a (meth) acryloyl group in one molecule, or a cation that can be cured by both light and heat It is preferable to use a system curing agent.

(Details and applications of anisotropic conductive materials)
The anisotropic conductive material according to the present invention is a paste-like or film-like anisotropic conductive material, and is preferably a paste-like anisotropic conductive material. The paste-like anisotropic conductive material is an anisotropic conductive paste. The film-like anisotropic conductive material is an anisotropic conductive film. When the anisotropic conductive material is an anisotropic conductive film, a film that does not include conductive particles may be laminated on the anisotropic conductive film that includes the conductive particles.

  The anisotropic conductive material which concerns on this invention can be used in order to adhere | attach various connection object members. The anisotropic conductive material is suitably used for obtaining a connection structure in which the first and second connection target members are electrically connected.

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

  The connection structure 1 shown in FIG. 1 includes a first connection target member 2, a second connection target member 4, and a cured product layer 3 connecting the first and second connection target members 2 and 4. Is provided. The cured product layer 3 is formed by curing an anisotropic conductive material including the conductive particles 5. In FIG. 1 and FIGS. 2A to 2C described later, the conductive particles are schematically shown.

  A plurality of electrodes 2 b are provided on the upper surface 2 a (front surface) of the first connection target member 2. A plurality of electrodes 4 b are provided on the lower surface 4 a (front surface) of the second connection target member 4. The electrode 2b and the electrode 4b are electrically connected by one or a plurality of conductive particles 5. Therefore, the first and second connection target members 2 and 4 are electrically connected by the conductive particles 5.

  Specifically, as the connection structure, an electronic component chip such as a semiconductor chip, a capacitor chip or a diode chip is mounted on a circuit board, and the electrode of the electronic component chip is connected to an electrode on the circuit board. Examples include electrically connected structures. As a circuit board, various printed circuit boards, such as various printed circuit boards, such as a flexible printed circuit board, a glass substrate, or a board | substrate with which metal foil was laminated | stacked are mentioned. The first and second connection target members are preferably electronic components or circuit boards.

  The connection structure 1 shown in FIG. 1 can be obtained as follows, for example, through the states shown in FIGS.

  As shown to Fig.2 (a), the 1st connection object member 2 which has the electrode 2b on the upper surface 2a is prepared. In addition, an anisotropic conductive material including a thermosetting compound, a thermosetting agent, conductive particles 5 and a filler is prepared. Next, an anisotropic conductive material including a plurality of conductive particles 5 is disposed on the upper surface 2a of the first connection target member 2, and the anisotropic conductive material layer 3A is disposed on the upper surface 2a of the first connection target member 2. Form and place. At this time, it is preferable that one or a plurality of conductive particles 5 be disposed on the electrode 2b. Here, since the anisotropic conductive paste is used as the anisotropic conductive material, the lamination of the anisotropic conductive paste is performed by applying the anisotropic conductive paste.

  Next, the anisotropic conductive material layer 3A is cured by irradiating light or applying heat to the anisotropic conductive material layer 3A. By curing the anisotropic conductive material layer 3A, the anisotropic conductive material layer 3A is B-staged. As shown in FIG. 2B, the anisotropic conductive material layer 3 </ b> B having the B stage is formed on the upper surface 2 a of the first connection target member 2 by making the anisotropic conductive material layer 3 </ b> A into the B stage. Form.

When the B-stage is formed by light irradiation, the light irradiation intensity at the time of light irradiation is in the range of 0.1 to 100 mW / cm ² in order to appropriately cure the anisotropic conductive material layer 3A. It is preferable to be within. The light source used when irradiating light is not specifically limited. Examples of the light source include a light source having a sufficient light emission distribution at a wavelength of 420 nm or less. Specific examples of the light source include, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, and a metal halide lamp.

  When the B stage is formed by applying heat, the heating temperature when the anisotropic conductive material layer 3A is B staged by applying heat is preferably 60 ° C or higher, more preferably 80 ° C or higher, preferably 120 ° C. or lower, more preferably 100 ° C. or lower.

  In addition, the anisotropic conductive material layer 3B that has been previously B-staged without applying the B-stage to the anisotropic conductive material layer 3A by irradiating light or applying heat on the upper surface 2a of the first connection target member 2. May be arranged on the upper surface 2 a of the first connection target member 2.

  Next, as shown in FIG. 2C, the second connection target member 4 is laminated on the upper surface 3a of the B-staged anisotropic conductive material layer 3B. The second connection target member 4 is laminated so that the electrode 2b on the upper surface 2a of the first connection target member 2 and the electrode 4b on the lower surface 4a of the second connection target member 4 face each other. When the second connection target member 4 is laminated, the anisotropic conductive material layer 3B is further cured by applying (heating) the anisotropic conductive material layer 3B to form the cured product layer 3. . At this time, the anisotropic conductive material layer 3B is cured by heating and pressurizing the upper surface 4c of the second connection target member 4 and applying heat to the anisotropic conductive material layer 3B. Is preferably formed. By compressing the conductive particles 5 with the electrodes 2b and 4b by pressurization, the contact area between the electrodes 2b and 4b and the conductive particles 5 can be increased. For this reason, conduction reliability can be improved. However, heat may be applied to the anisotropic conductive material layer 3B before the second connection target member 4 is laminated. Furthermore, heat may be applied to the anisotropic conductive material layer 3B after the second connection target member 4 is laminated.

  The heating temperature for curing the anisotropic conductive material layer 3B is preferably 130 ° C. or higher, preferably 250 ° C. or lower, more preferably 200 ° C. or lower, and further preferably 150 ° C. or lower.

  By curing the anisotropic conductive material layer 3 </ b> B, the first connection target member 2 and the second connection target member 4 are connected via the cured product layer 3. Further, the electrode 2 b and the electrode 4 b are electrically connected through the conductive particles 5. In this way, the connection structure 1 shown in FIG. 1 can be obtained.

  It is preferable to use a semiconductor chip as the second connection target member. When the upper surface of the semiconductor chip is heated and pressed to cure the anisotropic conductive material layer, the semiconductor chip tends to warp and voids tend to occur in the cured product layer. On the other hand, the use of the anisotropic conductive material according to the present invention can suppress the generation of voids even if the second connection target member is a semiconductor chip.

  The second connection target member may be heated at the time of manufacturing the connection structure. The temperature when the second connection target member is heated in advance is preferably 23 ° C. or higher, and preferably 120 ° C. or lower.

  The pressure when heating and pressurizing the first connection target member and the second connection target member is preferably 3 MPa or less, more preferably 1.5 MPa or less.

As the second connection target member, a second connection target member having an aspect ratio of 5 or more and a plane area of 10 mm ² or more is preferably used, and a semiconductor having an aspect ratio of 5 or more and a plane area of 10 mm ² or more. It is preferable to use a chip. The upper limit of the aspect ratio of the second connection target member is not particularly limited, but the aspect ratio is preferably 10 or less. The upper limit of the plane area of the second connection target member is not particularly limited, but the plane area is preferably 400 mm ² or less.

  It is preferable to use a glass epoxy board or a flexible printed board as the first connection target member. A flexible printed circuit board is preferably used as the second connection target member. In the manufacturing method of the connection structure according to the present invention, it is preferable to use a glass epoxy board or a flexible printed board as the first connection target member, and use a flexible printed board as the second connection target member.

The area to be superposed of the electrode pair is connected to the second connection object member is preferably 0.015 mm ² or more, preferably 0.2 mm ² or less. In the manufacturing method of the connection structure according to the present invention, a glass epoxy substrate or a flexible printed circuit board is used as the first connection target member, and the overlapping area of the pair of electrodes to which the second connection target member is connected is overlapped. There, 0.015 mm ² or more and 0.2 mm ² or less.

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

  In the examples and comparative examples, the following materials were used.

(Thermosetting compound)
CP-30: NOF Corporation, epoxy group-containing polymer EPR-4023: ADEKA company, CTBN-modified epoxy resin Episulfide compound represented by the following formula (1B): in-house synthesis

  Episulfide compound represented by the following formula (2B): in-house synthesis

  EX-201: manufactured by Nagase ChemteX Corporation, resorcin diglycidyl ether

(Thermosetting agent)
YH-306: manufactured by Mitsubishi Chemical Corporation, acid anhydride Sun Aid SI-60L: manufactured by Sanshin Chemical Industry Co., Ltd., cationic polymerization initiator Sun Aid SI-100: manufactured by Sanshin Chemical Industry Co., Ltd., cationic polymerization initiator

(Curing catalyst)
2E4MZ: Shikoku Kasei Kogyo Co., Ltd., imidazole compound

(Adhesive agent)
KBE-403: Shin-Etsu Chemical Co., Ltd., epoxy group-containing silane coupling agent

(Conductive particles)
Conductive particles A: The surface of resin core particles (divinylbenzene resin particles, diameter 10 μm, 10% K value: 3700 MPa, 20% K value: 3290 MPa) is covered with a 1 μm thick copper layer, and the surface of the copper layer Is coated with a 2 μm thick SnBi solder layer, average particle size: 16 μm, compression deformation recovery rate: 40%
Conductive particles B: The surface of resin core particles (divinylbenzene resin particles, diameter 10 μm, 10% K value: 3700 MPa, 20% K value: 3290 MPa) are covered with a 1 μm thick nickel layer, and the surface of the nickel layer Covered with a 2 μm thick SnBi solder layer, average particle size: 16 μm, compression deformation recovery rate: 30%
Conductive particles C: SnBi solder particles, average particle size: 15 μm

(Filler)
UFP-80: manufactured by Denki Kagaku Kogyo Co., Ltd., nano silica filler, primary average particle size: 34 nm, surface functional group: epoxy group, M value: 20
SC2500-SEJ: manufactured by Admatechs, nano silica filler, primary average particle size: 500 nm, surface functional group: epoxy group, M value: 30
QS-10: manufactured by Tokuyama Corporation, nano silica filler, primary average particle size: 10 nm, surface functional group: hydroxyl group, M value: 0
MT-10: manufactured by Tokuyama Corporation, nano silica filler, primary average particle size: 15 nm, surface functional group: silanol group, M value: 47

(Examples 1-8 and Comparative Examples 1-2)
(1) Preparation of anisotropic conductive material The components of the types shown in Tables 1 and 2 below were blended so as to have the blending amounts shown in Tables 1 and 2 below to obtain anisotropic conductive pastes. .

(2) Production of Connection Structure A flexible printed circuit board (first connection target member) having an L / S of 150 μm / 150 μm and a 1.5 mm long Au electrode pattern formed on the lower surface was prepared. Moreover, the glass epoxy board | substrate (2nd connection object member) in which the copper electrode pattern with L / S of 150 micrometers / 150 micrometers and length 3mm was formed in the upper surface was prepared.

  On the said glass epoxy board | substrate, the obtained anisotropic conductive paste was apply | coated using the dispenser so that it might become thickness 40 micrometers and width 2mm, and the anisotropic conductive paste layer was formed. Next, the flexible printed circuit board was laminated on the anisotropic conductive paste layer so that the electrodes face each other. Then, using “BD-02” manufactured by Ohashi Manufacturing Co., Ltd., adjusting the temperature of the thermocompression bonding head so that the temperature of the anisotropic conductive paste layer is 185 ° C. (final pressure bonding temperature). A pressure-bonding head was placed, and the anisotropic conductive paste layer was cured by applying a pressure of 1 MPa to obtain a connection structure.

(Examples 9 to 10)
A connection structure was produced in the same manner as in Example 1 except that the main pressure bonding temperature was changed from 185 ° C. to the temperature shown in Table 1 below. In Examples 9 to 10, the same anisotropic conductive paste as in Example 1 was used.

(Example 11)
The first connection target member is changed to a semiconductor chip (first connection target member, length 2 mm × width 10 mm, aspect ratio 5, plane area 20 mm ² ) having a copper electrode pattern with a pitch of 50 μm formed on the lower surface. A connection structure was produced in the same manner as in Example 1 except that the connection target member 2 was changed to a glass substrate having an ITO electrode pattern with a 50 μm pitch formed on the upper surface. In Example 11, the same anisotropic conductive paste as in Example 1 was used.

(Example 12)
Other than changing the first connection target member to a semiconductor chip (first connection target member, length 1 mm × width 15 mm, aspect ratio 15, plane area 15 mm ² ) on which a copper electrode pattern with a pitch of 50 μm is formed on the lower surface Were made in the same manner as in Example 1 to produce a connection structure. In Example 12, the same anisotropic conductive paste as in Example 1 was used.

(Examples 13 to 17)
An anisotropic conductive paste was obtained in the same manner as in Example 1 except that when preparing the anisotropic conductive material, the types and amounts of the compounding components were changed as shown in Table 2 below. A connection structure was obtained in the same manner as in Example 1 except that the obtained anisotropic conductive paste was used.

(Evaluation of Examples 1-17 and Comparative Examples 1-2)
(1) Viscosity η1 at room temperature
Viscosity η1 (10 rpm) under a condition of 10 rpm was measured using an E-type viscosity measuring device (manufactured by TOKI SANGYO CO. LTD, trade name: VISCOMETER TV-22, rotor used: φ15 mm, temperature: 25 ° C.). Similarly, the viscosity η1 (1 rpm) under the condition of 1 rpm was measured to obtain a thixo ratio 1: η1 (1 rpm) / η1 (10 rpm).

(2) Viscosity ratio (η2 / η3)
Using a rheometer (“STRESSTECH” manufactured by EOLOGICA), the measurement conditions are: strain control 1 rad, frequency 1 Hz, temperature increase rate 20 ° C./min, measurement temperature range 40 to 300 ° C., minimum melt viscosity η2, minimum melt The temperature showing the viscosity was measured. Further, the viscosity was measured in the same manner as described above except that the frequency was set to 10 Hz, the minimum melt viscosity η3 at the temperature showing the minimum melt viscosity was measured, and the viscosity ratio (η2 / η3) was obtained.

(3) Presence / absence of voids in the cured product layer in the connection structure In the obtained connection structure, whether or not voids are generated in the cured product layer obtained by curing the anisotropic conductive paste layer is determined by a flexible printed circuit board or a glass substrate. Observed from the side with an optical microscope. The presence or absence of voids was determined according to the following criteria.

[Criteria for the presence or absence of voids]
○○: No void ○: Slightly void, but no electrode L / S, no more void than pitch ×: There is a void larger than the size between adjacent electrodes

(4) Conductivity In the obtained connection structure (n = 15), the connection resistance of the electrode of the first connection target member and the electrode of the second connection target member facing each other is 25 by a four-terminal measurement method. Evaluated in place. The case where it was 20Ω or less among all the electrodes was judged as “◯”, and the case where it was larger than 20Ω even at one place was judged as “x”.

(5) Insulation In the obtained connection structure (n = 15), 5 V was applied between adjacent electrodes, and resistance values were measured at 25 locations. A case where all the electrodes were 500 MΩ or more was judged as “◯”, and a case where even one place was smaller than 500 MΩ was judged as “X”.

(6) Moisture and heat resistance test The obtained connection structures (n = 15) were allowed to stand for 168 hours under the conditions of 85 ° C. and 85% RH, and then similarly evaluated for conductivity and insulation. When both the results in the continuity and insulation criteria of (4) and (5) above are “◯”, any one of the results in the continuity and insulation criteria is “ The case of “x” was determined as “x”.

  The results are shown in Tables 1 and 2 below.

DESCRIPTION OF SYMBOLS 1 ... Connection structure 2 ... 1st connection object member 2a ... Upper surface 2b ... Electrode 3 ... Hardened | cured material layer 3a ... Upper surface 3A ... Anisotropic conductive material layer 3B ... An anisotropic conductive material layer made into B stage 4 ... 2nd connection object member 4a ... lower surface 4b ... electrode 4c ... upper surface 5 ... conductive particle 11 ... conductive particle 11a ... surface 12 ... resin particle 12a ... surface 13 ... conductive layer 14 ... first conductive layer 14a ... surface 15 ... Solder layer 21 ... Conductive particles 22 ... Solder layer

Claims (10)

Including a thermosetting compound, a thermosetting agent, conductive particles, and a filler;
The conductive particles have resin particles and a conductive layer disposed on the surface of the resin particles, and at least the outer surface layer of the conductive layer is a solder layer,
The filler is a nanofiller having an average primary particle diameter of 5 nm or more and 800 nm or less, or a filler having a reactive functional group on the surface,
An anisotropic conductive material having a minimum melt viscosity in a temperature range of 60 to 120 ° C. in a measurement temperature range of 40 to 300 ° C. and a minimum melt viscosity of 1 Pa · s or more.   The viscosity ratio of the viscosity (Pa · s) at 1 Hz at the temperature showing the lowest melt viscosity to the viscosity (Pa · s) at 10 Hz at the temperature showing the lowest melt viscosity is 3 or more. Anisotropic conductive material.   The anisotropic conductive material according to claim 1, wherein the anisotropic conductive material is an anisotropic conductive paste.   The anisotropic conductive material of any one of Claims 1-3 whose average particle diameter of the said electroconductive particle is 1 micrometer or more and 50 micrometers or less. The thermosetting compound is a thermosetting compound having an epoxy group or a thiirane group,
The anisotropic conductive material of any one of Claims 1-4 in which the said filler has a functional group which can react with an epoxy group or a thiirane group.   The anisotropy according to any one of claims 1 to 5, wherein the filler is a nanofiller having an average particle diameter of primary particles of 5 nm or more and 800 nm or less and having a reactive functional group on the surface. Conductive material. Disposing an anisotropic conductive material layer using the anisotropic conductive material according to any one of claims 1 to 6 on a first connection target member having an electrode on an upper surface;
Laminating a second connection object member having an electrode on the lower surface on the upper surface of the anisotropic conductive material layer;
Heating and pressurizing the upper surface of the second connection target member and applying heat to the anisotropic conductive material layer to cure the anisotropic conductive material layer to form a cured product layer; A method for manufacturing a connection structure.   The method for manufacturing a connection structure according to claim 7, wherein a semiconductor chip is used as the second connection target member. Wherein a second connection object member, an aspect ratio of 5 or more, a flat area using the second connection object member is 10 mm ² or more, a manufacturing method of a connection structure according to claim 7 or 8. A first connection target member, a second connection target member, and a cured product layer electrically connecting the first and second connection target members,
The connection structure in which the said hardened | cured material layer is formed by hardening the anisotropic electrically-conductive material of any one of Claims 1-6.

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