WO2011021522A1 - Curable composition, connected structures, and mercapto-containing (meth)acrylate compound - Google Patents

Abstract

Provided is a curable composition which can yield a cured product that exhibits a reduced moisture absorption and an enhanced bond strength to a member to be connected. Also provided is a novel (meth)acrylate compound containing a thiol group, which is usable as a material for the curable composition. The curable composition contains both a mercapto-containing (meth)acrylate compound and an initiator for actinic energy ray polymerization. The novel mercapto-containing (meth)acrylate compound has a structure represented by general formula (31) [wherein R1 and R2 are each hydrogen or a methyl group; R3 and R4 are each a C_1-5 alkylene group; X is a specific aromatic group; and Z1 and Z2 are each a mercapto group, or alternatively Z1 is a mercapto group with Z2 being a hydroxyl group].

Description

Curable composition, connection structure and mercapto group-containing (meth) acrylate compound

The present invention relates to a curable composition that can be used for connection of a connection target member such as an electronic component or a circuit board, and more specifically, a mercapto group-containing (meth) acrylate having a mercapto group and a (meth) acryloyl group. The present invention relates to a curable composition containing a compound, and a connection structure using the curable composition. The present invention also relates to a novel mercapto group-containing (meth) acrylate compound having a mercapto group and a (meth) acryloyl group.

A curable composition is used to connect various connection target members such as electronic components or circuit boards. The curable composition includes a photocurable resin or a thermosetting resin.

The curable composition is used, for example, for connection between a semiconductor chip provided with a metal bump electrode and a circuit board provided with the electrode.

Also, curable compositions containing conductive particles are known. A curable composition containing conductive particles is used, for example, for connection between an IC chip and a flexible printed circuit board or connection between an IC chip and a circuit board having an ITO electrode.

As an example of the curable composition, Patent Literature 1 below discloses a thermosetting or photocurable composition containing conductive particles, a base resin, and a hindered phenol polymerization inhibitor. Polyacetal resin and (meth) acrylic resin are described as the base resin.

JP 2003-20455 A

Development of materials that can be used for curable compositions as described in Patent Document 1 has been underway. Incidentally, a cured product of this type of curable composition may be required to have low hygroscopicity. Moreover, when a connection object member is connected with the hardened | cured material of a curable composition, it may be calculated | required that the adhesive force of hardened | cured material and a connection object member is high.

An object of the present invention is to provide a curable composition capable of reducing the hygroscopicity of a cured product after curing and increasing the adhesive force between the cured product and a connection target member, and the curable composition. It is to provide a connection structure used.

Another object of the present invention is to provide a novel thiol group-containing (meth) acrylate compound that can be used as a material for a curable composition.

According to a wide aspect of the present invention, there is provided a curable composition containing a mercapto group-containing (meth) acrylate compound and an active energy ray polymerization initiator.

In a specific aspect of the curable composition according to the present invention, the mercapto group-containing (meth) acrylate compound is a mercapto group-containing (meth) acrylate compound having a structure represented by the following formula (31).

In the above formula (31), R1 and R2 each represent hydrogen or a methyl group, and R3 and R4 each represent an alkylene group having 1 to 5 carbon atoms. In the above formula (31), X represents a group represented by any one of the following formulas (11) to (13). In the above formula (31), Z1 and Z2 both represent a mercapto group, or Z1 represents a mercapto group and Z2 represents a hydroxyl group.

In another specific aspect of the curable composition according to the present invention, Z1 and Z2 in the formula (31) are both mercapto groups.

In still another specific aspect of the curable composition according to the present invention, the mercapto group-containing (meth) acrylate compound having a structure represented by the above formula (31) has a structure represented by the following formula (1). A mercapto group-containing (meth) acrylate compound.

In the above formula (1), R1 and R2 each represent hydrogen or a methyl group, and X represents a group represented by any one of the above formulas (11) to (13).

The connection structure according to the present invention includes a first connection target member, a second connection target member, and a connection portion that connects the first and second connection target members. It is formed by curing a curable composition constituted according to the present invention.

Further, according to a wide aspect of the present invention, a mercapto group-containing (meth) acrylate compound having a structure represented by the following formula (31) is provided.

In the above formula (31), R1 and R2 each represent hydrogen or a methyl group, and R3 and R4 each represent an alkylene group having 1 to 5 carbon atoms. In the above formula (31), X represents a group represented by any one of the following formulas (11) to (13). In the above formula (31), Z1 and Z2 both represent a mercapto group, or Z1 represents a mercapto group and Z2 represents a hydroxyl group.

In a specific aspect of the mercapto group-containing (meth) acrylate compound according to the present invention, Z1 and Z2 in the formula (31) are both mercapto groups.

In another specific aspect of the mercapto group-containing (meth) acrylate compound according to the present invention, the mercapto group-containing (meth) acrylate compound having a structure represented by the above formula (31) is represented by the following formula (1). It is a mercapto group containing (meth) acrylate compound which has a structure.

In the above formula (1), R1 and R2 each represent hydrogen or a methyl group, and X represents a group represented by any one of the above formulas (11) to (13).

Since the curable composition according to the present invention contains a mercapto group-containing (meth) acrylate compound and an active energy ray polymerization initiator, the hygroscopicity of the cured product after curing can be lowered. Furthermore, when a connection object member is connected with the hardened | cured material of the curable composition which concerns on this invention, the adhesive force of hardened | cured material and a connection object member can be made high.

Since the mercapto group-containing (meth) acrylate compound according to the present invention has a structure represented by the above formula (31), it can be used as a material for a curable composition. This curable composition can be used for connection of various connection object members.

FIG. 1 is a front sectional view schematically showing an example of a connection structure using a curable composition containing a mercapto group-containing (meth) acrylate compound according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail.

The curable composition according to the present invention contains a mercapto group-containing (meth) acrylate compound and an active energy ray polymerization initiator. The mercapto group-containing (meth) acrylate compound according to the present invention is a mercapto group-containing (meth) acrylate compound having a structure represented by the formula (31). Mercapto groups are SH groups. It is preferable that the curable composition concerning this invention contains the mercapto group containing (meth) acrylate compound represented by Formula (31).

(Mercapto group-containing (meth) acrylate compound)
The mercapto group-containing (meth) acrylate compound contained in the curable composition according to the present invention has a mercapto group and a (meth) acryloyl group. By using the mercapto group-containing (meth) acrylate compound, the hygroscopicity of the cured product of the curable composition can be lowered. Furthermore, the adhesive force between the cured product and the connection target member can be increased.

The mercapto group-containing (meth) acrylate compound according to the present invention has a structure represented by the following formula (31).

The mercapto group-containing (meth) acrylate compound contained in the curable composition according to the present invention is preferably a mercapto group-containing (meth) acrylate compound having a structure represented by the following formula (31). By using a mercapto group-containing (meth) acrylate compound having a structure represented by the following formula (31), the hygroscopicity of the cured product of the curable composition can be sufficiently lowered. Furthermore, the adhesive force between the cured product and the connection target member can be sufficiently increased. However, the curable composition concerning this invention may contain the mercapto group containing (meth) acrylate compound other than the mercapto group containing (meth) acrylate compound represented by Formula (31).

In the above formula (31), R1 and R2 each represent hydrogen or a methyl group, and R3 and R4 each represent an alkylene group having 1 to 5 carbon atoms. In the above formula (31), X represents a group represented by any one of the following formulas (11) to (13). In the above formula (31), Z1 and Z2 both represent a mercapto group, or Z1 represents a mercapto group and Z2 represents a hydroxyl group.

That is, the compound having the structure represented by the above formula (31) has a structure represented by any one of the following formulas (31A) to (31C).

In the above formula (31A), R1 and R2 each represent hydrogen or a methyl group, and R3 and R4 each represent an alkylene group having 1 to 5 carbon atoms. In the above formula (31A), Z1 and Z2 both represent a mercapto group, or Z1 represents a mercapto group and Z2 represents a hydroxyl group.

In the above formula (31B), R1 and R2 each represent hydrogen or a methyl group, and R3 and R4 each represent an alkylene group having 1 to 5 carbon atoms. In the above formula (31B), Z1 and Z2 both represent a mercapto group, or Z1 represents a mercapto group and Z2 represents a hydroxyl group.

In the above formula (31C), R1 and R2 each represent hydrogen or a methyl group, and R3 and R4 each represent an alkylene group having 1 to 5 carbon atoms. In the above formula (31C), Z1 and Z2 both represent a mercapto group, or Z1 represents a mercapto group and Z2 represents a hydroxyl group.

The mercapto group-containing (meth) acrylate compound having a structure represented by the above formula (31) has a mercapto group and a (meth) acryloyl group. The group having the mercapto group and the (meth) acryloyl group is bonded to a specific aromatic ring, and is bonded to a benzene ring or a naphthalene ring. Since it has such a structure, for example, by adding an active energy ray polymerization initiator to a mercapto group-containing (meth) acrylate compound to obtain a curable composition, the curable composition is irradiated with active energy rays. The curable composition can be cured.

When the carbon number of the alkylene group of R3 and R4 in the above formula (31) exceeds 5, the curing rate of the curable composition tends to be slow. R3 and R4 in the above formula (31) are each preferably a methylene group. In this case, the curing rate of the curable composition is further increased.

In the above formula (31), both Z1 and Z2 are preferably mercapto groups. In the compound in which Z1 and Z2 in the formula (31) are both mercapto groups, the cured product of the curable composition as compared with the compound in which Z1 in the formula (31) is a mercapto group and Z2 is a hydroxyl group. Hygroscopicity can be lowered.

In the above formula (31), R3 and R4 are each preferably a methylene group, and both Z1 and Z2 are preferably mercapto groups. That is, the mercapto group-containing (meth) acrylate compound having a structure represented by the above formula (31) preferably has a structure represented by the following formula (1).

In the above formula (1), R1 and R2 each represent hydrogen or a methyl group. In the above formula (1), X represents a group represented by any one of the above formulas (11) to (13).

That is, the compound having the structure represented by the above formula (1) has a structure represented by any one of the following formulas (1A) to (1C).

In the above formula (1A), R1 and R2 each represent hydrogen or a methyl group.

In the above formula (1B), R1 and R2 each represent hydrogen or a methyl group.

In the above formula (1C), R1 and R2 each represent hydrogen or a methyl group.

It is preferable that R1 and R2 in the above (31) and the above formula (1) are each hydrogen. In this case, the curability of the mercapto group-containing (meth) acrylate compound is even better.

In the above formula (31), R1 and R2 are each preferably hydrogen, R3 and R4 are each a methylene group, and both Z1 and Z2 are preferably mercapto groups. That is, the mercapto group-containing (meth) acrylate compound having a structure represented by the above formula (31) preferably has a structure represented by the following formula (21). The mercapto group-containing (meth) acrylate compound having a structure represented by the following formula (21) is more excellent in curability.

In the above formula (21), X represents a group represented by any one of the above formulas (11) to (13).

That is, the compound having a structure represented by the above formula (21) has a structure represented by any of the following formulas (21A) to (21C).

The above “(meth) acrylate” indicates acrylate and methacrylate. The “(meth) acryl” refers to acryl and methacryl. The “(meth) acryloyl” refers to acryloyl and methacryloyl.

(Method for producing mercapto group-containing (meth) acrylate compound)
Mercapto group-containing (meth) acrylate compound having a structure represented by the above formula (31), that is, a mercapto group-containing (meth) acrylate having a structure represented by any of the above formulas (31A) to (31C) The method for producing the compound is not particularly limited, and can be obtained, for example, as follows.

An epoxy compound represented by any of the following formulas (71A) to (71C) (hereinafter also referred to as epoxy compound A) is prepared.

In the above formula (71A), R3 and R4 each represents an alkylene group having 1 to 5 carbon atoms.

In the above formula (71B), R3 and R4 each represent an alkylene group having 1 to 5 carbon atoms.

In the above formula (71C), R3 and R4 each represent an alkylene group having 1 to 5 carbon atoms.

Next, all the epoxy groups of the epoxy compound A are converted into episulfide groups (thiirane groups), and an episulfide compound represented by any one of the following formulas (81A) to (81C) (hereinafter also referred to as episulfide compound B1) Say). Alternatively, a part of the epoxy group of the epoxy compound A is converted into an episulfide group to obtain an episulfide compound represented by any one of the following formulas (82A) to (82C) (hereinafter also referred to as episulfide compound B2). . The episulfide compound is a thiirane group-containing compound. The episulfide compound represented by any of the following formulas (82A) to (82C) is also an epoxy compound and is an epoxy group-containing episulfide compound.

In the above formula (81A), R3 and R4 each represents an alkylene group having 1 to 5 carbon atoms.

In the above formula (81B), R3 and R4 each represent an alkylene group having 1 to 5 carbon atoms.

In the above formula (81C), R3 and R4 each represent an alkylene group having 1 to 5 carbon atoms.

In the above formula (82A), R3 and R4 each represents an alkylene group having 1 to 5 carbon atoms.

In the above formula (82B), R3 and R4 each represent an alkylene group having 1 to 5 carbon atoms.

In the above formula (82C), R3 and R4 each represents an alkylene group having 1 to 5 carbon atoms.

The epoxy compound A preferably has a structure represented by any of the following formulas (51A) to (51C). Epoxy compounds having structures represented by the following formulas (51A) to (51C) are easily available.

By using an epoxy compound having a structure represented by the above formulas (51A) to (51C), a structure represented by any of the following formulas (61A) to (61C), (62A) to (62C) is obtained. The episulfide compound which has can be obtained.

The production method of the episulfide compounds B1 and B2 is preferably a production method in which a sulfurizing agent and the epoxy compound A are mixed. By this production method, the epoxy group of the epoxy compound A can be converted into an episulfide group.

Examples of the sulfurizing agent include thiocyanates, thioureas, phosphine sulfide, dimethylthioformamide, N-methylbenzothiazole-2-thione, and the like. Other sulfurizing agents may be used. Of these, thiocyanates or thioureas are preferable, and thiocyanates are more preferable. Examples of the thiocyanates include sodium thiocyanate, potassium thiocyanate, and sodium thiocyanate. Examples of the thioureas include thiourea, N-methylthiourea and 1,3-diethylthiourea.

The sulfurizing agent is preferably used within a range of 10 to 1000 parts by weight with respect to 100 parts by weight of the epoxy compound A. The sulfiding agent is more preferably used in the range of 80 to 110 parts by weight with respect to 100 parts by weight of the epoxy compound A. If the amount of the sulfurizing agent used is too small, the epoxy group may not be sufficiently converted to an episulfide group. If the amount of the sulfurizing agent used is too large, the effect of converting an epoxy group to an episulfide group may be saturated.

A solvent may be used when mixing the sulfiding agent and the epoxy compound A. Further, the sulfiding agent and the epoxy compound A may be added to a solvent and used as a solution. Examples of the solvent include water and organic solvents. Examples of the organic solvent include methanol and ethanol.

The solvent is preferably used in the range of 100 to 3000 parts by weight with respect to 100 parts by weight of the epoxy compound A. The solvent is more preferably used in the range of 200 to 1500 parts by weight with respect to 100 parts by weight of the epoxy compound A. If the amount of the solvent used is too small, the epoxy compound A may be polymerized. If the amount of the solvent used is too large, the cost may increase.

It is preferable to remove water, a solvent and an unreacted sulfurizing agent after converting the epoxy group of the epoxy compound A to an episulfide group. Water, solvent and unreacted sulfiding agent can be removed by a conventionally known method.

Further, a catalyst may be used in the reaction of the epoxy compound A. By using the above catalyst, the conversion rate to the episulfide group can be adjusted. Moreover, since an epoxy group can be converted into an episulfide group in a low temperature environment, the polymerization reaction of the epoxy compound A can be suppressed.

Examples of the catalyst include a palladium catalyst, titanium oxide, and cyanuric acid chloride. Examples of the palladium catalyst include palladium metal particles.

The catalyst is preferably used in the range of 0.02 to 3 parts by weight with respect to 100 parts by weight of the epoxy compound A. When the amount of the catalyst used is within the above range, the epoxy group can be more efficiently converted by the episulfide group in a low temperature environment.

Next, by reacting the episulfide compounds B1 and B2 with (meth) acrylic acid, a mercapto group-containing (meth) acrylate compound having a structure represented by the above formula (31) can be obtained.

The (meth) acrylic acid is preferably used within a range of 40 to 120 parts by weight with respect to 100 parts by weight of the episulfide compounds B1 and B2. When the amount of the (meth) acrylic acid used is within the above range, the (meth) acryloyl group can be introduced more efficiently.

A solvent may be used when mixing the episulfide compounds B1 and B2 with the (meth) acrylic acid. Further, the episulfide compound B and the (meth) acrylic acid may be added to a solvent and used as a solution. Examples of the solvent include water and organic solvents. Examples of the organic solvent include methanol, ethanol, toluene, and the like.

The solvent is preferably used in the range of 50 to 300 parts by weight with respect to 100 parts by weight of the episulfide compounds B1 and B2. When the amount of the solvent used is within the above range, the (meth) acryloyl group can be introduced more efficiently.

In the reaction of the episulfide compounds B1 and B2 with the (meth) acrylic acid, a catalyst or a polymerization inhibitor may be used.

Examples of the catalyst include triethylamine, benzyldimethylamine, N, N′-dimethylpiperidine, 2,4,6-tris (dimethylaminomethyl) phenol, triethylenediamine, trimethylbenzylammonium chloride, tetra-n-butylammonium bromide, chloride Examples include lithium and triphenylphosphine. Examples of the polymerization inhibitor include hydroquinone, hydroquinone monomethyl ether, benzoquinone, pt-butylcatechol, and 2,6-dibutyl-4-methylphenol.

The catalyst is preferably used in the range of 0.5 to 5 parts by weight with respect to 100 parts by weight of the episulfide compounds B1 and B2. When the amount of the catalyst used is within the above range, the (meth) acryloyl group can be introduced more efficiently. The polymerization inhibitor is preferably used in the range of 0.2 to 1.5 parts by weight with respect to 100 parts by weight of the episulfide compounds B1 and B2. When the usage-amount of the said polymerization inhibitor exists in the said range, a (meth) acryloyl group can be introduce | transduced much more efficiently.

(Active energy ray polymerization initiator)
The curable composition according to the present invention can be obtained by adding an active energy ray polymerization initiator to the mercapto group-containing (meth) acrylate compound. The said curable composition can be hardened by irradiating an active energy ray to a curable composition. As the active energy ray polymerization initiator, a commercially available photopolymerization initiator can be used.

Specific examples of the photopolymerization initiator include acetophenone photopolymerization initiator, ketal photopolymerization initiator, halogenated ketone, acyl phosphinoxide, and acyl phosphonate. You may use photoinitiators other than these. As for the said photoinitiator, only 1 type may be used and 2 or more types may be used together.

Specific examples of the acetophenone photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, methoxy Examples include acetophenone, 2,2-dimethoxy-1,2-diphenylethane-1-one, and 2-hydroxy-2-cyclohexylacetophenone. Specific examples of the ketal photopolymerization initiator include benzyl dimethyl ketal.

The content of the active energy ray polymerization initiator is preferably in the range of 0.05 to 10 parts by weight with respect to 100 parts by weight of the mercapto group-containing (meth) acrylate compound. The content of the active energy ray polymerization initiator is preferably 0.1 parts by weight or more, more preferably 7.5 parts by weight or less, still more preferably 100 parts by weight of the mercapto group-containing (meth) acrylate compound. 5 parts by weight or less. The effect which added the said active energy ray polymerization initiator can fully be acquired as content of the said active energy ray polymerization initiator is more than the said minimum. The adhesive force of the hardened | cured material of the said curable composition becomes still higher that content of the said active energy ray polymerization initiator is below the said upper limit.

(Other components that can be blended in the curable composition)
The curable composition according to the present invention preferably further contains a filler. By using the filler, latent heat expansion of the cured product of the curable composition can be suppressed. As for the said filler, only 1 type may be used and 2 or more types may be used together.

Specific examples of the filler include silica, aluminum nitride, and alumina. The filler is preferably filler particles. The filler particles preferably have an average particle size in the range of 0.1 to 1.0 μm. When the average particle diameter of the filler particles is within the above range, the latent heat expansion of the cured product of the curable composition can be further suppressed. The “average particle diameter” indicates a volume average diameter measured by a dynamic laser scattering method.

The content of the filler is preferably in the range of 50 to 900 parts by weight with respect to 100 parts by weight of the mercapto group-containing (meth) acrylate compound. When content of the said filler exists in the said range, the latent heat expansion of the hardened | cured material of the said curable composition can be suppressed further.

The curable composition may further contain a solvent, an ion scavenger, or a silane coupling agent as necessary.

The solvent is not particularly limited. Examples of the solvent include ethyl acetate, methyl cellosolve, toluene, acetone, methyl ethyl ketone, cyclohexane, n-hexane, tetrahydrofuran and diethyl ether. As for the said solvent, only 1 type may be used and 2 or more types may be used together.

The silane coupling agent is not particularly limited. Examples of the silane coupling agent include N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, and N- (2-aminoethyl). ) -3-Aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, 3-aminopropyldimethylethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxy Silane, 3-aminopropyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyltriacetoxysilane, vinyltrichlorosilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycid Cypropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacrylic Roxypropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, dodecyltriethoxysilane, hexyltrimethoxysilane, isobutyldiethoxysilane , Methylphenyldiethoxysilane, methylphenyldimethoxysilane, and imidazolesilane. Of these, imidazolesilane is preferable. As for the said silane coupling agent, only 1 type may be used and 2 or more types may be used together.

The ion scavenger is not particularly limited. Specific examples of the ion scavenger include aluminosilicate, hydrous titanium oxide, hydrous bismuth oxide, zirconium phosphate, titanium phosphate, hydrotalcite, ammonium molybdate, hexacyanozinc and ion exchange resin. As for the said ion trapping agent, only 1 type may be used and 2 or more types may be used together.

The curable composition can be used as a one-component adhesive for bonding a liquid crystal panel or a semiconductor chip. The curable composition may be a paste-like adhesive or a film-like adhesive.

The method for processing the curable composition into a film adhesive is not particularly limited. For example, the curable composition is applied to a substrate such as a release paper and processed into a film adhesive, or a solvent is added to the curable composition and applied to a substrate such as a release paper. Then, the method of volatilizing a solvent and processing it into a film adhesive is mentioned.

The active energy rays irradiated when the curable composition is cured include ultraviolet rays, electron beams, α rays, β rays, γ rays, X rays, infrared rays and visible rays. Among these active energy rays, ultraviolet rays or electron beams are preferable because they are excellent in curability and hardened products are hardly deteriorated.

The light source used when the curable composition is irradiated with light such as ultraviolet rays is not particularly 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 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. Of these, a chemical lamp is preferable. The chemical lamp efficiently emits light in the active wavelength region of the photopolymerization initiator and has a small amount of light emission in the light absorption wavelength region of the composition components other than the photopolymerization initiator. Furthermore, by using a chemical lamp, light can efficiently reach the photopolymerization initiator present in the curable composition.

For example, when a cleavage type photopolymerization initiator having an acetophenone group is included, the light irradiation intensity in the wavelength region of 365 nm to 420 nm may be in the range of 0.1 to 100 mW / cm ^2. preferable.

The curable composition may contain conductive particles. A curable composition containing conductive particles can be used as an anisotropic conductive material.

The conductive particles electrically connect, for example, electrodes between a circuit board and a semiconductor chip. The conductive particles are not particularly limited as long as they are conductive particles. The surface of the conductive layer of the conductive particles may be covered with an insulating layer or insulating particles. In this case, the insulating layer or insulating particles between the conductive layer and the electrode are excluded when the connection target member is connected. Examples of the conductive particles include conductive particles whose surfaces are coated with a metal layer, such as organic particles, inorganic particles, organic-inorganic hybrid particles, and metal particles, and metal particles that are substantially composed only of metal. It is done. The metal layer is not particularly limited. Examples of the metal layer include a gold layer, a silver layer, a copper layer, a nickel layer, a palladium layer, and a metal layer containing tin.

The content of the conductive particles is not particularly limited. The content of the conductive particles is preferably 0.1 parts by weight or more, more preferably 0.5 parts by weight or more, preferably 10 parts by weight or less with respect to 100 parts by weight of the mercapto group-containing (meth) acrylate compound. More preferably, it is 5 parts by weight or less. When the content of the conductive particles is not less than the above lower limit, the electrodes and the like can be more reliably conducted. When the content of the conductive particles is less than or equal to the above upper limit, a short circuit between adjacent electrodes that should not be conducted is further less likely to occur.

When the curable composition is liquid or pasty, the viscosity (25 ° C.) of the curable composition is preferably in the range of 20000 to 100,000 mPa · s. When the viscosity of the curable composition is within the above range, the curable composition can be easily applied. Moreover, when the viscosity of the said curable composition containing the said electroconductive particle is too low, electroconductive particle may precipitate, and when a viscosity is too high, electroconductive particle may not fully disperse | distribute.

(Use of curable composition)
The curable composition concerning this invention can be used in order to adhere | attach various connection object members.

The curable composition is suitable for obtaining a connection structure in which a first connection target member provided with a metal bump electrode and a second connection target member provided with an electrode are electrically connected. Used for.

Further, when the curable composition is an anisotropic conductive material containing conductive particles, the anisotropic conductive material includes an anisotropic conductive paste, an anisotropic conductive ink, and an anisotropic conductive adhesive. It can be used as an agent, an anisotropic conductive film, or an anisotropic conductive sheet. When the anisotropic conductive material is used as a film-like adhesive such as an anisotropic conductive film or anisotropic conductive sheet, the film-like adhesive containing the conductive particles contains conductive particles. The film-like adhesive which does not carry out may be laminated | stacked.

The anisotropic conductive material is preferably used to obtain a connection structure in which the first and second connection target members are electrically connected.

FIG. 1 schematically shows an example of a connection structure using a curable composition according to an embodiment of the present invention.

A connection structure 1 shown in FIG. 1 is a connection that electrically connects a first connection target member 2, a second connection target member 3, and first and second connection target members 2 and 3. Part 4. The connection part 4 is formed by hardening the said curable composition. In the connection structure 1, an anisotropic conductive material including conductive particles 5 is used as the curable composition.

A plurality of electrodes 2 b are provided on the upper surface 2 a of the first connection target member 2. A plurality of electrodes 3 b are provided on the lower surface 3 a of the second connection target member 3. The electrode 2 b and the electrode 3 b 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 manufacturing method of the connection structure is not particularly limited. As an example of a method for manufacturing a connection structure, the anisotropic conductive material is provided between a first connection target member such as an electronic component or a circuit board and a second connection target member such as an electronic component or a circuit board. Examples of the method include arranging and obtaining a laminate, and then heating and pressurizing the laminate.

Since the curable composition contains the mercapto group-containing (meth) acrylate compound, the hygroscopicity of the cured product of the curable composition can be lowered. Furthermore, the adhesive force with respect to the metal of the hardened | cured material of the said curable composition can be made high. Therefore, the curable composition obtains a connection structure in which the first connection target member provided with the metal bump electrode and the second connection target member provided with the electrode are electrically connected. More preferably. Moreover, the said curable composition is used suitably also for forming this hardened | cured material layer in the laminated body provided with a metal plate and the hardened | cured material layer laminated | stacked on the at least one surface of this metal plate.

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 active energy ray polymerization initiators, fillers and conductive particles were appropriately used.

(Active energy ray polymerization initiator)
Photopolymerization initiator A ("DAROCUR TPO" manufactured by Ciba)
Photopolymerization initiator B (Ciba “IRGUCURE 819”)
Photopolymerization initiator C (“IRGUCURE1122” manufactured by Ciba)

(Filler)
Silica (average particle size 0.25μm)
Alumina (average particle size 0.5μm)

(Conductive particles)
Conductive particles (having a metal layer in which a nickel plating layer is formed on the surface of divinylbenzene resin particles and a gold plating layer is formed on the surface of the nickel plating layer)

Example 1
In Example 1, a mercapto group-containing (meth) acrylate compound represented by the following formula (21A) was synthesized.

(1) Synthesis of episulfide compound represented by the above formula (61A) 100 parts by weight of resorcinol diglycidyl ether which is an epoxy compound represented by the above formula (51A), 80 parts by weight of potassium thiocyanate, and 20 parts by weight of acetonitrile And 0.005 parts by weight of a palladium catalyst (“Tetraammine palladium chloride” manufactured by Tanaka Kikinzoku Co., Ltd.), 500 parts by weight of ethanol and 50 parts by weight of water are mixed and stirred to convert the epoxy group to an episulfide group. An episulfide compound represented by the above formula (61A) was obtained.

The obtained episulfide compound was subjected to ¹ H-NMR measurement using chloroform as a solvent. As a result, the signal in the 6.5 to 7.5 ppm region indicating the presence of the epoxy group disappeared, and the signal appeared in the 2.0 to 3.0 ppm region indicating the presence of the episulfide group. This confirmed that the epoxy group of resorcinol diglycidyl ether was converted into an episulfide group.

(2) Synthesis of mercapto group-containing (meth) acrylate compound represented by formula (21A) 100 parts by weight of the obtained episulfide compound represented by formula (61A), 80 parts by weight of acrylic acid, and toluene 100 Part by weight, 5 parts by weight of hydroquinone and 5 parts by weight of tetra-n-butylammonium bromide were mixed and heated to 100 ° C. while introducing oxygen, and contained a mercapto group represented by the above formula (21A) ( A (meth) acrylate compound was obtained.

¹ H-NMR measurement of the obtained mercapto group-containing (meth) acrylate compound was performed using chloroform as a solvent. As a result, the signal in the region of 2.0 to 3.0 ppm indicating the presence of the episulfide group disappeared, and the signal in the region of 2.5 to 3 ppm indicating the presence of the mercapto group appeared. In addition, a signal in the region of 4 to 6 ppm indicating the presence of acryloyl group appeared. This confirmed that the mercapto group-containing (meth) acrylate compound represented by the above formula (21A) was obtained.

(3) Preparation of curable composition To 100 parts by weight of the obtained mercapto group-containing (meth) acrylate compound represented by the above formula (21A), a photopolymerization initiator A (“DAROCUR TPO” manufactured by Ciba) was added. A curable composition was obtained by adding 5 parts by weight and stirring for 5 minutes at 2000 rpm using a planetary stirrer.

(Example 2)
In Example 2, a mercapto group-containing (meth) acrylate compound represented by the following formula (21B) was synthesized.

(1) Synthesis of Episulfide Compound Represented by Formula (61B) Above Example 1 except that the compound represented by Formula (51A) was changed to the epoxy compound represented by Formula (51B). 1) The episulfide compound represented by the above formula (61B) was obtained in the same manner as the synthesis of the episulfide compound.

The obtained episulfide compound was subjected to ¹ H-NMR measurement using chloroform as a solvent. As a result, the signal in the 6.5 to 7.5 ppm region indicating the presence of the epoxy group disappeared, and the signal appeared in the 2.0 to 3.0 ppm region indicating the presence of the episulfide group. This confirmed that the epoxy group of the epoxy compound represented by the above formula (51B) was converted to an episulfide group.

(2) Synthesis of mercapto group-containing (meth) acrylate compound represented by the above formula (21B) The episulfide compound represented by the above formula (61A) is converted into the obtained episulfide compound represented by the above formula (61B). A mercapto group-containing (meth) acrylate compound represented by the above formula (21B) was obtained in the same manner as in the synthesis of the (2) mercapto group-containing (meth) acrylate compound of Example 1 except that it was changed.

¹ H-NMR measurement of the obtained mercapto group-containing (meth) acrylate compound was performed using chloroform as a solvent. As a result, the signal in the region of 2.0 to 3.0 ppm indicating the presence of the episulfide group disappeared, and the signal in the region of 2.5 to 3 ppm indicating the presence of the mercapto group appeared. In addition, a signal in the region of 4 to 6 ppm indicating the presence of acryloyl group appeared. This confirmed that the mercapto group-containing (meth) acrylate compound represented by the above formula (21B) was obtained.

(3) Preparation of curable composition The mercapto group-containing (meth) acrylate compound represented by the above formula (21A) is changed to the obtained mercapto group-containing (meth) acrylate compound represented by the above formula (21B). Except that, a curable composition was obtained in the same manner as in the preparation of the curable composition in Example 1, (3).

(Example 3)
In Example 3, a mercapto group-containing (meth) acrylate compound represented by the following formula (21C) was synthesized.

(1) Synthesis of Episulfide Compound Represented by Formula (61C) The compound of Example 1 except that the compound represented by Formula (51A) was changed to the epoxy compound represented by Formula (51C) above. 1) The episulfide compound represented by the above formula (61C) was obtained in the same manner as the synthesis of the episulfide compound.

The obtained episulfide compound was subjected to ¹ H-NMR measurement using chloroform as a solvent. As a result, the signal in the 6.5 to 7.5 ppm region indicating the presence of the epoxy group disappeared, and the signal appeared in the 2.0 to 3.0 ppm region indicating the presence of the episulfide group. This confirmed that the epoxy group of the epoxy compound represented by the above formula (51C) was converted to an episulfide group.

(2) Synthesis of mercapto group-containing (meth) acrylate compound represented by the above formula (21C) The episulfide compound represented by the above formula (61A) is converted into the obtained episulfide compound represented by the above formula (61C). A mercapto group-containing (meth) acrylate compound represented by the above formula (21C) was obtained in the same manner as in the synthesis of the (2) mercapto group-containing (meth) acrylate compound of Example 1 except that it was changed.

¹ H-NMR measurement of the obtained mercapto group-containing (meth) acrylate compound was performed using chloroform as a solvent. As a result, the signal in the region of 2.0 to 3.0 ppm indicating the presence of the episulfide group disappeared, and the signal in the region of 2.5 to 3 ppm indicating the presence of the mercapto group appeared. In addition, a signal in the region of 4 to 6 ppm indicating the presence of acryloyl group appeared. This confirmed that the mercapto group-containing (meth) acrylate compound represented by the above formula (21C) was obtained.

(3) Preparation of curable composition The mercapto group-containing (meth) acrylate compound represented by the above formula (21A) is changed to the obtained mercapto group-containing (meth) acrylate compound represented by the above formula (21C). Except that, a curable composition was obtained in the same manner as in the preparation of the curable composition in Example 1, (3).

(Comparative Example 1)
In Comparative Example 1, a hydroxyl group-containing (meth) acrylate compound represented by the following formula (101A) was synthesized.

(1) Synthesis of hydroxyl group-containing (meth) acrylate compound represented by formula (101A) 100 parts by weight of resorcinol diglycidyl ether which is an epoxy compound represented by formula (51A), 80 parts by weight of acrylic acid, A mixture containing 50 parts by weight of toluene, 5 parts by weight of hydroquinone and 5 parts by weight of tetra-n-butylammonium bromide, heated to 100 ° C. while introducing oxygen, and containing a hydroxyl group represented by the above formula (101A) A (meth) acrylate compound was obtained.

The resulting hydroxyl group-containing (meth) acrylate compound was subjected to ¹ H-NMR measurement using chloroform as a solvent. As a result, the signal in the region of 6.5 to 7.5 ppm indicating the presence of the epoxy group disappeared, and the signal in the region of 2.5 to 3.5 ppm indicating the presence of the hydroxyl group appeared. In addition, a signal in the region of 4 to 6 ppm indicating the presence of acryloyl group appeared. This confirmed that the hydroxyl group-containing (meth) acrylate compound represented by the above formula (101A) was obtained.

(2) Preparation of curable composition The mercapto group-containing (meth) acrylate compound represented by the above formula (21A) was changed to the obtained hydroxyl group-containing (meth) acrylate compound represented by the above formula (101A). Except for this, a curable composition was obtained in the same manner as in the preparation of the curable composition in Example 1, (3).

(Comparative Example 2)
In Comparative Example 2, a hydroxyl group-containing (meth) acrylate compound represented by the following formula (101B) was synthesized.

(1) Synthesis of hydroxyl group-containing (meth) acrylate compound represented by the above formula (101B) Except that the epoxy compound represented by the above formula (51A) is changed to the epoxy compound represented by the above formula (51B) In the same manner as in Comparative Example 1, a hydroxyl group-containing (meth) acrylate compound represented by the above formula (101B) was obtained.

The resulting hydroxyl group-containing (meth) acrylate compound was subjected to ¹ H-NMR measurement using chloroform as a solvent. As a result, the signal in the region of 6.5 to 7.5 ppm indicating the presence of the epoxy group disappeared, and the signal in the region of 2.5 to 3.5 ppm indicating the presence of the hydroxyl group appeared. In addition, a signal in the region of 4 to 6 ppm indicating the presence of acryloyl group appeared. This confirmed that the hydroxyl group-containing (meth) acrylate compound represented by the above formula (101B) was obtained.

(2) Preparation of curable composition The mercapto group-containing (meth) acrylate compound represented by the formula (21A) was changed to the hydroxyl group-containing (meth) acrylate compound represented by the obtained formula (101B). Except for this, a curable composition was obtained in the same manner as in the preparation of the curable composition in Example 1, (3).

(Comparative Example 3)
In Comparative Example 3, a hydroxyl group-containing (meth) acrylate compound represented by the following formula (101C) was synthesized.

(1) Synthesis of hydroxyl group-containing (meth) acrylate compound represented by the above formula (101C) Except for changing the epoxy compound represented by the above formula (51A) to the epoxy compound represented by the above formula (51C) In the same manner as in Comparative Example 1, a hydroxyl group-containing (meth) acrylate compound represented by the above formula (101C) was obtained.

The resulting hydroxyl group-containing (meth) acrylate compound was subjected to ¹ H-NMR measurement using chloroform as a solvent. As a result, the signal in the region of 6.5 to 7.5 ppm indicating the presence of the epoxy group disappeared, and the signal in the region of 2.5 to 3.5 ppm indicating the presence of the hydroxyl group appeared. A signal in the region of 4-6 ppm indicating the presence of acryloyl group appeared. This confirmed that the hydroxyl group-containing (meth) acrylate compound represented by the above formula (101C) was obtained.

(2) Preparation of curable composition The mercapto group-containing (meth) acrylate compound represented by the above formula (21A) was changed to the obtained hydroxyl group-containing (meth) acrylate compound represented by the above formula (101C). Except for this, a curable composition was obtained in the same manner as in the preparation of the curable composition in Example 1, (3).

(Evaluation of Examples 1 to 3 and Comparative Examples 1 to 3)
(1) Hygroscopicity Using an LED spot UV device manufactured by HOYA, the obtained curable composition was irradiated with 375 nm light at a light irradiation intensity of 1500 mW / cm ² for 5 seconds to cure the curable composition. A film-like cured product (length 6 mm × width 6 mm × thickness 1 mm) of the curable composition was obtained. The obtained cured product was allowed to stand for 24 hours at 80 ° C. and a relative humidity of 85%. The hygroscopicity was evaluated by determining the weight change of the cured product before and after standing by a method based on JIS K7209. The smaller the change in weight, the lower the hygroscopicity.

(2) Adhesive force A transparent glass substrate having an ITO electrode provided on the upper surface was prepared. In addition, a semiconductor chip having a gold bump electrode provided on the lower surface was prepared.

On the said transparent glass substrate, the obtained curable composition was applied so that it might become thickness of 30 micrometers, and the curable composition layer was formed. Next, the semiconductor chip was laminated on the curable composition layer so that the electrodes face each other. Thereafter, using a LED spot UV device manufactured by HOYA, the curable composition layer was irradiated with 375 nm light at a light irradiation intensity of 1500 mW / cm ² for 5 seconds to cure the curable composition layer, and the connection structure. Got.

The adhesive strength was evaluated by measuring the shear strength of the obtained connection structure using a universal bond tester series 4000 manufactured by Days.
The results are shown in Table 1 below.

(Examples 4 to 12)
Mercapto group-containing (meth) acrylate compounds corresponding to mercapto group-containing (meth) acrylate compounds represented by the formula (31) of the type shown in Table 2 below were synthesized. A curable composition was obtained in the same manner as in the preparation of the (3) curable composition of Example 1 except that the obtained mercapto group-containing (meth) acrylate compound was used.

In Examples 4 to 6, acrylic acid was changed to methacrylic acid in the synthesis of (2) mercapto group-containing (meth) acrylate compound of Examples 1 to 3. In Examples 7 to 12, in the synthesis of the episulfide compound represented by Formula (61A) in Example 1 (1), the compounds represented by the above Formulas (71A) to (71C) are substituted for resorcinol diglycidyl ether. Wherein R3 and R4 in formulas (71A) to (71C) are each an n-propylene group (n-C ₃ H ₆ ) or an n-pentylene group (n-C ₅ H ₁₀ ) Epoxy compounds were used as appropriate.

(Examples 13 to 19)
A curable composition having the composition shown in Table 3 below was prepared. In Examples 13 to 19, the mercapto group-containing (meth) acrylate compound having the structure represented by the above formulas (21A) to (21C) obtained in Examples 1 to 3, the photopolymerization initiator described above, The filler and the conductive particles described above were appropriately used.

(Example 20)
(1) Synthesis of Episulfide Compound In the synthesis of the episulfide compound represented by Formula (61A) in Example 1 (1), the amount of potassium thiocyanate used was reduced, the conversion rate was adjusted, and the above formula ( The mixture X1 of the epoxy compound represented by 51A), the epoxy group-containing episulfide compound represented by the above formula (62A), and the episulfide compound represented by the above formula (61A) was obtained. The conversion ratio of epoxy groups to episulfide groups in the entire mixture X1 was 50%. That is, the ratio of the number of epoxy groups to episulfide groups (epoxy groups: episulfide groups) in the obtained mixture X1 was 1: 1.

(2) Synthesis of mercapto group-containing (meth) acrylate compound (2) Mercapto group-containing (meta) of Example 1 except that the episulfide compound represented by the above formula (61A) was changed to the obtained mixture X1. ) Similar to the synthesis of the acrylate compound, the hydroxyl group-containing (meth) acrylate compound represented by the above formula (101A), the hydroxyl group and mercapto group-containing (meth) acrylate compound represented by the following formula (22A), and the above A mixture Y1 with a mercapto group-containing (meth) acrylate compound represented by the formula (21A) was obtained.

(3) Preparation of curable composition (3) Curable composition of Example 1 except having changed the mercapto group containing (meth) acrylate compound represented by the said Formula (21A) into the said mixture Y1 obtained. In the same manner as the preparation of the product, a curable composition was obtained.

(Example 21)
(1) Synthesis of episulfide compound In the synthesis of the episulfide compound represented by formula (61) of Example 2 (1), the amount of potassium thiocyanate used was reduced, the conversion rate was adjusted, and the above formula ( A mixture X2 of the epoxy compound represented by 51B), the epoxy group-containing episulfide compound represented by the above formula (62B), and the episulfide compound represented by the above formula (61B) was obtained. The conversion ratio of epoxy groups to episulfide groups in the entire mixture X2 was 50%. That is, the ratio of the number of epoxy groups to episulfide groups (epoxy groups: episulfide groups) in the obtained mixture X2 was 1: 1.

(2) Synthesis of mercapto group-containing (meth) acrylate compound (2) Mercapto group-containing (meta) of Example 2 except that the episulfide compound represented by the formula (61B) was changed to the obtained mixture X2. ) Similar to the synthesis of the acrylate compound, the hydroxyl group-containing (meth) acrylate compound represented by the above formula (101B), the hydroxyl group and mercapto group-containing (meth) acrylate compound represented by the following formula (22B), and the above A mixture Y2 with a mercapto group-containing (meth) acrylate compound represented by the formula (21B) was obtained.

(3) Preparation of curable composition (3) Curable composition of Example 1 except having changed the mercapto group containing (meth) acrylate compound represented by the said Formula (21A) into the said mixture Y2 obtained. In the same manner as the preparation of the product, a curable composition was obtained.

(Example 22)
(1) Synthesis of Episulfide Compound In the synthesis of the episulfide compound represented by Formula (61C) of Example 3 (1), the amount of potassium thiocyanate used was reduced, the conversion rate was adjusted, and the above formula ( A mixture X3 of the epoxy compound represented by 51C), the epoxy group-containing episulfide compound represented by the above formula (62C), and the episulfide compound represented by the above formula (61C) was obtained. The conversion ratio of epoxy groups to episulfide groups in the entire mixture X3 was 50%. That is, the ratio of the number of epoxy groups to episulfide groups (epoxy groups: episulfide groups) in the obtained mixture X3 was 1: 1.

(2) Synthesis of mercapto group-containing (meth) acrylate compound (2) Mercapto group-containing (meta) of Example 3 except that the episulfide compound represented by the above formula (61C) was changed to the obtained mixture X3. ) Similar to the synthesis of the acrylate compound, the hydroxyl group-containing (meth) acrylate compound represented by the above formula (101C), the hydroxyl group and mercapto group-containing (meth) acrylate compound represented by the following formula (22C), and the above A mixture Y3 with a mercapto group-containing (meth) acrylate compound represented by the formula (21C) was obtained.

(3) Preparation of curable composition (3) Curable composition of Example 1 except having changed the mercapto group containing (meth) acrylate compound represented by the said Formula (21A) into the said mixture Y3 obtained. In the same manner as the preparation of the product, a curable composition was obtained.

(Evaluation of Examples 4 to 22)
The curable compositions of Examples 4 to 22 were evaluated for the same evaluation items as in Examples 1 to 3 and Comparative Examples 1 to 3.

The results are shown in Tables 2 to 3 below. However, in Tables 2 to 3 below, the evaluation results of the hygroscopicity and the adhesive strength are the results of the determination based on the following criteria.

[Hygroscopic criteria]
○: Weight change is less than 1.5% ○: Weight change is 1.5% or more and less than 2.5% Δ: Weight change is 2.5% or more and less than 3.5% ×: Weight change is 3%. 5% or more

[Adhesion criteria]
○○: shear strength is, 800N / cm ² or more ○: shear strength is, 675N / cm ² or more and less than 800N / cm ² △: shear strength is, 550N / cm ² or more, 675N / cm ² less than ×: shear strength Is less than 550 N / cm ²

DESCRIPTION OF SYMBOLS 1 ... Connection structure 2 ... 1st connection object member 2a ... Upper surface 2b ... Electrode 3 ... 2nd connection object member 3a ... Lower surface 3b ... Electrode 4 ... Connection part 5 ... Conductive particle

Claims (8)

1. A curable composition containing a mercapto group-containing (meth) acrylate compound and an active energy ray polymerization initiator.
2. The curable composition according to claim 1, wherein the mercapto group-containing (meth) acrylate compound is a mercapto group-containing (meth) acrylate compound having a structure represented by the following formula (31).
   

   

   In the formula (31), R1 and R2 each represent hydrogen or a methyl group, R3 and R4 each represent an alkylene group having 1 to 5 carbon atoms, and X represents one of the following formulas (11) to (13): Represents a group represented by any of the above. In the above formula (31), Z1 and Z2 both represent a mercapto group, or Z1 represents a mercapto group and Z2 represents a hydroxyl group.
   

   

   

   
3. The curable composition according to claim 2, wherein Z1 and Z2 in the formula (31) are both mercapto groups.
4. The mercapto group-containing (meth) acrylate compound having a structure represented by the formula (31) is a mercapto group-containing (meth) acrylate compound having a structure represented by the following formula (1). Curable composition.
   

   

   In the formula (1), R1 and R2 each represent hydrogen or a methyl group, and X represents a group represented by any one of the formulas (11) to (13).
5. A first connection target member, a second connection target member, and a connection part connecting the first and second connection target members;
   A connection structure, wherein the connection portion is formed by curing the curable composition according to any one of claims 1 to 4.
6. A mercapto group-containing (meth) acrylate compound having a structure represented by the following formula (31).
   

   

   In the formula (31), R1 and R2 each represent hydrogen or a methyl group, R3 and R4 each represent an alkylene group having 1 to 5 carbon atoms, and X represents one of the following formulas (11) to (13): Represents a group represented by any of the above. In the above formula (31), Z1 and Z2 both represent a mercapto group, or Z1 represents a mercapto group and Z2 represents a hydroxyl group.
   

   

   

   
7. The mercapto group-containing (meth) acrylate compound according to claim 6, wherein Z1 and Z2 in the formula (31) are both mercapto groups.
8. The mercapto group-containing (meth) acrylate compound according to claim 6, which is a mercapto group-containing (meth) acrylate compound having a structure represented by the following formula (1).
   

   

   In the formula (1), R1 and R2 each represent hydrogen or a methyl group, and X represents a group represented by any one of the formulas (11) to (13).

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