JP7673644B2 - Underfill material, semiconductor package, and method for manufacturing semiconductor package - Google Patents

Description

The present disclosure relates to an underfill material, a semiconductor package, and a method for manufacturing a semiconductor package.

In the field of encapsulation of various semiconductor elements used in semiconductor devices such as transistors and ICs (Integrated Circuits), encapsulation with resin is mainstream due to its productivity and manufacturing costs. Epoxy resin is widely used as an encapsulating resin. This is because epoxy resin has an excellent balance of properties such as workability, moldability, electrical properties, moisture resistance, heat resistance, mechanical properties, and adhesion to insert products.

In recent years, in the field of semiconductor devices, in order to accommodate the trend towards smaller and thinner packages, semiconductor devices with bare chip mounting, in which bare chips are mounted directly on wiring boards, have become mainstream. Examples of semiconductor devices with bare chip mounting include COB (Chip on Board), COG (Chip on Glass), and TCP (Tape Carrier Package).

In flip-chip type semiconductor devices in which semiconductor elements are bump-connected to a wiring board, a liquid resin composition is used as an underfill material to fill the gap between the bump-connected semiconductor element and the board. For example, Patent Document 1 describes an underfill material using a multifunctional epoxy resin and a hardener containing a phenolic compound and an acid anhydride. The underfill material protects electronic components from temperature, humidity, and external mechanical forces.

In flip-chip semiconductor devices, solder balls have traditionally been used primarily to connect semiconductor elements to substrates. However, as the number of terminals increases due to miniaturization and high integration of semiconductor devices, copper pillars with solder caps at the ends are increasingly being used instead of conventional solder balls. As a result, defects occur in which the underfill material peels off from the copper pillars during the process of connecting semiconductor devices to motherboards and the like at high temperatures (e.g., 260°C) using a reflow furnace.

As a method for improving the adhesion of an epoxy resin composition to copper, for example, Patent Documents 2 to 6 describe epoxy resin compositions containing compounds that have excellent adhesion to copper.

JP 2004-256646 A JP 2007-2170 A Patent Publication 2012-188629 JP 2016-169300 A JP 2016-34906 A JP 2017-2289 A

However, when compounds that generally have excellent adhesion to copper are applied to underfill materials, they often react with resin components such as epoxy resins and hardeners, deteriorating the pot life, i.e., storage stability at room temperature. Furthermore, the adhesive strength of underfill materials to copper at high temperatures (e.g., 260°C) has not been verified until now.

In view of the above circumstances, the present disclosure aims to provide an underfill material that has an excellent pot life and excellent high-temperature adhesion to copper when cured, as well as a semiconductor package comprising the cured underfill material and a method for manufacturing the same.

Means for solving the above problems include the following embodiments.
<1> An underfill material comprising an epoxy resin, an aromatic amine curing agent, an inorganic filler, and a compound having a triazine ring and an alkoxysilyl group.
<2> The underfill material according to <1>, wherein the compound having a triazine ring and an alkoxysilyl group has a melting point of 200° C. or lower.
<3> The underfill material according to <1> or <2>, wherein the compound having a triazine ring and an alkoxysilyl group further has a primary amino group.
<4> An underfill material comprising an epoxy resin, an aromatic amine curing agent, an inorganic filler, and a compound having a triazine ring and a primary amino group and having a melting point of 200° C. or lower.
<5> A semiconductor package comprising: a substrate; a semiconductor element disposed on the substrate; and a cured product of the underfill material according to any one of <1> to <4> that encapsulates the semiconductor element.
<6> A method for manufacturing a semiconductor package, comprising: a step of filling a gap between a substrate and a semiconductor element disposed on the substrate with the underfill material according to any one of <1> to <5>; and a step of hardening the underfill material.

The present disclosure provides an underfill material that has an excellent pot life and, when cured, has excellent high-temperature adhesion to copper, as well as a semiconductor package including the cured underfill material and a method for manufacturing the same.

The following describes in detail the embodiments of the present disclosure. However, the embodiments of the present disclosure are not limited to the following embodiments. In the following embodiments, the components (including element steps, etc.) are not essential unless specifically stated otherwise. The same applies to numerical values and their ranges, and do not limit the embodiments of the present disclosure.

In the present disclosure, the term "step" includes not only a step that is independent of other steps, but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved.
In the present disclosure, the numerical ranges indicated using "to" include the numerical values before and after "to" as the minimum and maximum values, respectively.
In the numerical ranges described in the present disclosure in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.
In the present disclosure, each component may contain multiple types of the corresponding substance. When multiple substances corresponding to each component are present in the composition, the content or amount of each component means the total content or amount of the multiple substances present in the composition, unless otherwise specified.
In the present disclosure, multiple types of particles corresponding to each component may be included. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

<Underfill material>
The underfill material according to the first embodiment of the present disclosure contains an epoxy resin, an aromatic amine curing agent, an inorganic filler, and a compound having a triazine ring and an alkoxysilyl group (hereinafter also referred to as a "first triazine ring-containing compound").
An underfill material according to a second embodiment of the present disclosure contains an epoxy resin, an aromatic amine curing agent, an inorganic filler, and a compound having a triazine ring and a primary amino group and having a melting point of 200° C. or less (hereinafter also referred to as a “second triazine ring-containing compound”).
Hereinafter, the underfill material according to the first embodiment and the underfill material according to the second embodiment may be collectively referred to as the "underfill material of the present disclosure" or simply as the "underfill material."

The underfill material of the present disclosure has an excellent pot life and, when cured, has excellent high-temperature adhesion to copper. In this disclosure, high-temperature adhesion refers to adhesion at 260° C. The detailed reasons why the underfill material of the present disclosure has an excellent pot life and high-temperature adhesion to copper when cured are not necessarily clear, but are presumed to be as follows.
The underfill material according to the first embodiment contains a compound having a triazine ring and an alkoxysilyl group (first triazine ring-containing compound). It is believed that the nitrogen atom in the triazine ring contributes to high-temperature adhesion to copper. In addition, due to the presence of the alkoxysilyl group, the first triazine ring-containing compound has excellent compatibility with epoxy resins and disperses well in the underfill material, so that it is believed that the high-temperature adhesion is good throughout the underfill material. Furthermore, when the first triazine ring-containing compound is used and an aromatic amine compound is used as a curing agent, the reactivity of the first triazine ring-containing compound and the aromatic amine compound with respect to the epoxy group is not too high, so that the gelation proceeds relatively slowly and an excellent pot life is obtained.
The underfill material according to the second embodiment contains a compound (second triazine ring-containing compound) having a triazine ring and a primary amino group and a melting point of 200° C. or less. The nitrogen atom and the primary amino group in the triazine ring are believed to contribute to high-temperature adhesion with copper. In addition, since the compound has a melting point of 200° C. or less, it is believed that the compound has excellent dispersibility in the epoxy resin during kneading (e.g., about 25° C. to 80° C.), during filling in the gap between the element and the substrate (e.g., about 100° C. to 120° C.), and during curing of the underfill material (e.g., about 80° C. to 200° C.), and that the high-temperature adhesion is good throughout the underfill material. Furthermore, when the second triazine ring-containing compound is used and an aromatic amine compound is used as a curing agent, the reactivity of the second triazine ring-containing compound and the aromatic amine compound with respect to the epoxy resin is not too high, so that the gelation proceeds relatively slowly and an excellent pot life is obtained.

It is preferable that the underfill material is liquid at 25°C. In this disclosure, "liquid" means a substance that exhibits flowability and viscosity, and has a viscosity, a measure of viscosity, of 0.0001 Pa·s to 100 Pa·s. Additionally, "liquid state" means being in a liquid state.

In this disclosure, viscosity is the measured value when an EHD type rotational viscometer (e.g., VISCONIC EHD type (product name) manufactured by Tokyo Keiki Co., Ltd.) is rotated at 10 revolutions per minute (10 rpm) for 1 minute at 25°C. The above measured value is obtained for a liquid kept at 25±1°C using an EHD type rotational viscometer equipped with a cone rotor with a cone angle of 3° and a cone radius of 14 mm.

The viscosity of the underfill material is not particularly limited. From the viewpoint of high fluidity, the viscosity of the underfill material at 25°C is preferably 0.1 Pa·s to 100.0 Pa·s, more preferably 0.1 Pa·s to 50.0 Pa·s, and even more preferably 0.1 Pa·s to 30.0 Pa·s.

As an indicator of the ease of filling narrow gaps of several tens to several hundreds of microns at around 100°C to 120°C, the viscosity of the underfill material at 110°C is preferably 0.20 Pa·s or less, and more preferably 0.15 Pa·s or less. The viscosity of the underfill material at 110°C is measured using a rheometer (e.g., AR2000 manufactured by TA Instruments, cone radius 20 mm, shear rate 32.5/sec).

The pot life of the underfill material after being left at 25°C for 24 hours, as measured by the following method, is preferably 100% or less, more preferably 90% or less, even more preferably 80% or less, and particularly preferably 60% or less. There is no particular lower limit for the pot life, and the lower the value, the more preferable it is.
The underfill material is left at 25°C for 24 hours, and then the viscosity at 25°C is measured using an E-type viscometer (e.g., VISCONIC EHD (product name) manufactured by Tokyo Keiki Co., Ltd.) (cone angle 3°, rotation speed 10 revolutions per minute (rpm)) (viscosity after leaving). However, for samples that cannot be measured at a rotation speed of 10 revolutions per minute (rpm) due to high viscosity, the measurement is performed at 2.5 revolutions per minute (rpm). The pot life (%) is calculated as the viscosity increase rate after leaving for 24 hours using the following formula.
Pot life (%)={(viscosity after standing−initial viscosity)/initial viscosity}×100

The high-temperature adhesive strength of the underfill material to copper (Cu), measured by the following method, is preferably 0.70 kgf or more, more preferably 0.80 kgf or more, and even more preferably 0.90 kgf or more. The higher the high-temperature adhesive strength, the better.

The adhesion to copper can be measured, for example, as follows: A test piece is prepared by molding the underfill material to a diameter of 3 mm and a height of 3 mm on the surface of a copper plate, and a bond tester (e.g., DS100 model manufactured by DAGE) is used to apply shear stress at a head speed of 50 μm/sec to measure the strength at which the molded product peels off from the copper plate. Specifically, it can be measured by the method described in the examples.

<Epoxy resin>
The type of epoxy resin is not particularly limited, but the epoxy resin is preferably an epoxy resin having two or more epoxy groups in one molecule.

The epoxy resin may be solid or liquid at room temperature, and solid and liquid epoxy resins may be used in combination. From the viewpoint of reducing the viscosity of the underfill material, it is preferable to use an epoxy resin that is liquid at room temperature. From the viewpoint of fluidity during molding, it is preferable that the content of solid epoxy resin is 20 mass% or less of the total amount of epoxy resin.

The type of epoxy resin is not particularly limited. Specific examples of epoxy resins include novolac-type epoxy resins such as phenol novolac-type epoxy resins and cresol novolac-type epoxy resins; bisphenol-type epoxy resins such as bisphenol A-type epoxy resins and bisphenol F-type epoxy resins; glycidylamine-type epoxy resins such as N,N-diglycidylaniline, N,N-diglycidyltoluidine, diaminodiphenylmethane-type glycidylamine, and aminophenol-type glycidylamine; phenol aralkyl-type epoxy resins having at least one selected from the group consisting of a phenylene skeleton and a biphenylene skeleton; aralkyl-type epoxy resins such as naphthol aralkyl-type epoxy resins having at least one selected from the group consisting of a phenylene skeleton and a biphenylene skeleton; haloaralkyl-type epoxy resins having at least one selected from the group consisting of a naphthol aralkyl-type epoxy resin having at least one selected from the group consisting of a naphthol aralkyl-type epoxy resin; Examples of the epoxy resin include hydroquinone type epoxy resin, biphenyl type epoxy resin, stilbene type epoxy resin, triphenolmethane type epoxy resin, triphenolpropane type epoxy resin, alkyl-modified triphenolmethane type epoxy resin, triazine nucleus-containing epoxy resin, dicyclopentadiene-modified phenol type epoxy resin, naphthol type epoxy resin, naphthalene type epoxy resin, alicyclic epoxy resin such as vinylcyclohexene dioxide, dicyclopentadiene oxide, and alicyclic diepoxy-adipate, and difunctional aliphatic epoxy compounds having two epoxy groups in the molecule such as alkylene glycol diglycidyl ether, poly(alkylene glycol) diglycidyl ether, and alkenylene glycol diglycidyl ether. The epoxy resin may be used alone or in combination of two or more.

When two or more types of epoxy resins are used, the two or more types of epoxy resins may be premixed and then mixed with the other components, or they may be mixed with the other components without premixing.

The epoxy equivalent of the epoxy resin is not particularly limited. The epoxy equivalent of the epoxy resin may be 60 g/eq or more, 70 g/eq or more, or 90 g/eq or more. The epoxy equivalent of the epoxy resin may be 500 g/eq or less, 300 g/eq or less, or 200 g/eq or less. From the viewpoint of the balance of various properties such as moldability, reflow resistance, and electrical reliability, it is preferably 60 g/eq to 500 g/eq, more preferably 70 g/eq to 300 g/eq, and even more preferably 90 g/eq to 200 g/eq. The epoxy equivalent of the epoxy resin is a value measured by a method conforming to JIS K 7236:2009.

The content of the epoxy resin relative to the total mass of the underfill material is not particularly limited. The content of the epoxy resin relative to the total mass of the underfill material may be 0.5% by mass or more, or 2% by mass or more. The content of the epoxy resin relative to the total mass of the underfill material may be 50% by mass or less, 40% by mass or less, or 30% by mass or less. From the viewpoints of viscosity, glass transition temperature, heat resistance, etc., the content of the epoxy resin is preferably 0.5% by mass to 50% by mass, more preferably 2% by mass to 40% by mass, and even more preferably 5% by mass to 30% by mass, relative to the total mass of the underfill material.

In one aspect, from the viewpoint of injectability and reduction in the coefficient of thermal expansion when cured, the underfill material preferably contains at least one selected from the group consisting of bisphenol-type epoxy resin, glycidylamine-type epoxy resin, and naphthalene-type epoxy resin. It is more preferable that the underfill material contains all of bisphenol-type epoxy resin, glycidylamine-type epoxy resin, and naphthalene-type epoxy resin.

The type of bisphenol type epoxy resin is not particularly limited, and examples thereof include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, etc. The bisphenol type epoxy resin may be used alone or in combination of two or more types. From the viewpoint of using the underfill material in a liquid state, it is preferable that the bisphenol type epoxy resin is liquid at room temperature (25°C). From the viewpoint of reducing viscosity, it is preferable that the bisphenol type epoxy resin is a bisphenol F type epoxy resin.

When the underfill material contains a bisphenol type epoxy resin, the content of the bisphenol type epoxy resin is not particularly limited and can be selected according to the desired properties of the underfill material. For example, the content of the bisphenol F type epoxy resin may be 20 mass% or more, 30 mass% or more, or 40 mass% or more relative to the total mass of the epoxy resin. The content of the bisphenol F type epoxy resin may be less than 90 mass%, 80 mass% or less, or 70 mass% or less relative to the total mass of the epoxy resin. The content of the bisphenol F type epoxy resin may be 20 mass% or more and less than 90 mass%, 30 mass% to 80 mass%, or 40 mass% to 70 mass% relative to the total mass of the epoxy resin.

The type of glycidylamine type epoxy resin is not particularly limited. The glycidylamine type epoxy resin is preferably bifunctional or more, and from the viewpoint of improving heat resistance after curing, trifunctional or more (i.e., having three or more epoxy groups in one molecule) glycidylamine type epoxy resins are preferred. Examples of bifunctional glycidylamine type epoxy resins include N,N-diglycidylaniline and N,N-diglycidyl-o-toluidine. Examples of trifunctional or more glycidylamine type epoxy resins include triglycidyl-p-aminophenol and 4,4'-methylenebis[N,N-bis(oxiranylmethyl)aniline]. The glycidylamine type epoxy resins may be used alone or in combination of two or more. Among them, triglycidyl-p-aminophenol is preferred from the viewpoint of viscosity at room temperature (25°C).

From the viewpoint of reducing the viscosity of the underfill material, it is preferable that the molecular weight of the glycidyl amine type epoxy resin is 300 or less.

When the underfill material contains a glycidylamine type epoxy resin, the content of the glycidylamine type epoxy resin is not particularly limited. For example, the content of the glycidylamine type epoxy resin may be 10 mass% or more, 20 mass% or more, or 25 mass% or more, based on the total mass of the epoxy resin. The content of the glycidylamine type epoxy resin may be 60 mass% or less, 50 mass% or less, or 40 mass% or less, based on the total mass of the epoxy resin. The content of the glycidylamine type epoxy resin may be 10 mass% to 60 mass%, 20 mass% to 50 mass%, or 25 mass% to 40 mass%, based on the total mass of the epoxy resin.

The type of naphthalene-type epoxy resin is not particularly limited. From the viewpoint of reducing the thermal expansion coefficient, 1,6-bis(glycidyloxy)naphthalene is preferred.

When the underfill material contains a naphthalene-type epoxy resin, the content of the naphthalene-type epoxy resin is not particularly limited. For example, the content of the naphthalene-type epoxy resin may be 10 mass% or more, or 15 mass% or more, based on the total mass of the epoxy resin. The content of the naphthalene-type epoxy resin may be 30 mass% or less, or 25 mass% or less, based on the total mass of the epoxy resin. The content of the naphthalene-type epoxy resin may be 10 mass% to 30 mass% or 15 mass% to 25 mass% based on the total mass of the epoxy resin.

<Aromatic amine curing agent>
The type of aromatic amine curing agent is not particularly limited, and is preferably an aromatic amine compound having two or more groups selected from the group consisting of primary amino groups and secondary amino groups in one molecule, more preferably an aromatic amine compound having two to four groups selected from the group consisting of primary amino groups and secondary amino groups in one molecule, and even more preferably an aromatic amine compound having two groups selected from the group consisting of primary amino groups and secondary amino groups in one molecule. The aromatic amine curing agent is preferably liquid at 25°C.

Examples of aromatic amine curing agents include diethyltoluenediamines such as 3,5-diethyltoluene-2,4-diamine and 3,5-diethyltoluene-2,6-diamine; triethyldiaminobenzenes such as 1,3,5-triethyl-2,6-diaminobenzene; and diaminodiphenylmethanes such as 3,3'-diethyl-4,4'-diaminodiphenylmethane and 3,5,3',5'-tetramethyl-4,4'-diaminodiphenylmethane. Aromatic amine curing agents may be used alone or in combination of two or more.

Among these, from the viewpoint of storage stability, at least one selected from the group consisting of diaminodiphenylmethane and diethyltoluenediamine is preferred, and it is even more preferred to use these in combination.

The active hydrogen equivalent of the aromatic amine curing agent is not particularly limited. The active hydrogen equivalent of the aromatic amine curing agent may be 20 g/eq or more, 30 g/eq or more, or 40 g/eq or more. The active hydrogen equivalent of the aromatic amine curing agent may be 200 g/eq or less, 100 g/eq or less, or 80 g/eq or less. From the viewpoint of achieving both reduced thermal stress and a high glass transition temperature (Tg) of the cured product, it is preferably 20 g/eq to 200 g/eq, more preferably 30 g/eq to 100 g/eq, and even more preferably 40 g/eq to 80 g/eq.

The underfill material may contain other curing agents in addition to the aromatic amine curing agent. Examples of curing agents other than aromatic amine curing agents include aliphatic amine curing agents, phenolic curing agents, acid anhydride curing agents, imidazole compounds, imidazoline compounds, polymercaptan curing agents, polyaminoamide curing agents, isocyanate curing agents, and blocked isocyanate curing agents.

The content of the aromatic amine curing agent relative to the total mass of the curing agent is not particularly limited, and from the viewpoint of obtaining particularly good pot life and high-temperature adhesion to copper when the cured product is formed, it is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. In particular, the total content of at least one selected from the group consisting of diaminodiphenylmethane and diethyltoluenediamine is preferably 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more, relative to the total mass of the curing agent.

There are no particular limitations on the equivalent ratio between the epoxy resin and the curing agent (including aromatic amine curing agents), i.e., the ratio of the number of functional groups (active hydrogen in the case of amine curing agents) in the curing agent to the number of epoxy groups in the epoxy resin (number of functional groups in the curing agent/number of epoxy groups in the epoxy resin). From the viewpoint of keeping the amount of unreacted components low, it is preferable to set it in the range of 0.5 to 2.0, and more preferably in the range of 0.6 to 1.3. From the viewpoint of moldability and reflow resistance, it is even more preferable to set it in the range of 0.8 to 1.2.

From the viewpoint of making the underfill material liquid at room temperature (25°C), it is preferable to select a curing agent such that the entire curing agent is liquid at room temperature. In other words, when only one type of curing agent is used, it is preferable that the curing agent is liquid at room temperature. When a combination of two or more types of curing agents is used, the two or more types of curing agents may all be liquid at room temperature, or a combination of two or more types of curing agents, some of which are solid at room temperature, may be used such that when mixed together, the two or more types of curing agents become liquid at room temperature. When a curing agent that is solid at room temperature is used as the curing agent, its content is preferably 20 mass% or less of the total mass of the curing agent from the viewpoint of fluidity.

<Inorganic filler>
The type of inorganic filler is not particularly limited, and examples thereof include inorganic materials such as silica, glass, alumina, calcium carbonate, zirconium silicate, calcium silicate, silicon nitride, aluminum nitride, boron nitride, beryllia, zirconia, zircon, fosterite, steatite, spinel, mullite, titania, talc, clay, and mica. Inorganic fillers having a flame retardant effect may be used. Examples of inorganic fillers having a flame retardant effect include aluminum hydroxide, magnesium hydroxide, composite metal hydroxides such as composite hydroxides of magnesium and zinc, and zinc borate. The inorganic fillers may be used alone or in combination of two or more. Among them, silica is preferred from the viewpoint of reducing the thermal expansion coefficient, and alumina is preferred from the viewpoint of improving thermal conductivity.

The content of the inorganic filler is not particularly limited. The content of the inorganic filler may be 30% by mass or more, 40% by mass or more, or 50% by mass or more, based on the total mass of the underfill material. The content of the inorganic filler may be 90% by mass or less, 80% by mass or less, or 75% by mass or less, based on the total mass of the underfill material. From the viewpoint of achieving both good fluidity and the desired effect of the inorganic filler, the content of the inorganic filler is preferably 30% by mass to 90% by mass, more preferably 40% by mass to 80% by mass, and even more preferably 50% by mass to 75% by mass, based on the total mass of the underfill material.

When the inorganic filler is particulate, its average particle diameter is not particularly limited. For example, the volume average particle diameter of the inorganic filler may be 0.2 μm or more, or 0.5 μm or more. The volume average particle diameter of the inorganic filler may be 20 μm or less, or 15 μm or less. The volume average particle diameter of the inorganic filler is preferably 0.2 μm to 20 μm, and more preferably 0.5 μm to 15 μm. When the volume average particle diameter is 0.2 μm or more, the increase in viscosity of the underfill material tends to be more suppressed. When the volume average particle diameter is 20 μm or less, the filling ability into narrow gaps tends to be more improved. The volume average particle diameter of the inorganic filler can be measured as the particle diameter (D50) when the cumulative volume from the small diameter side becomes 50% in the volume-based particle size distribution obtained by a laser scattering diffraction method particle size distribution measuring device.

<Triazine ring-containing compound>
--First triazine ring-containing compound--
The first triazine ring-containing compound has a triazine ring and an alkoxysilyl group.
The position of the nitrogen in the triazine ring is not particularly limited. That is, the triazine skeleton may be any of 1,2,3-triazine, 1,2,4-triazine, and 1,3,5-triazine.

The first triazine ring-containing compound has a structure in which at least one of the hydrogen atoms bonded to three carbon atoms on triazine (C ₃ H ₃ N ₃ ) is substituted with a monovalent group having an alkoxysilyl group. The substitution position of the monovalent group may be any of the three carbon atoms. The number of substitutions of the monovalent group may be any of 1 to 3, preferably 1 or 2, and more preferably 1.

When the number of substitutions of a monovalent group having an alkoxysilyl group in the first triazine ring-containing compound is 1 or 2, a carbon atom on the triazine ring to which a monovalent group having an alkoxysilyl group is not bonded may be bonded with a substituent other than the monovalent group having an alkoxysilyl group, or may not be bonded with a substituent.

The monovalent group having an alkoxysilyl group may be an alkoxysilyl group itself, or may be a monovalent group formed by bonding a linking group to the silicon atom of the alkoxysilyl group. When the monovalent group having an alkoxysilyl group is a monovalent group formed by bonding a linking group to the silicon atom of the alkoxysilyl group, the linking group may be, for example, a hydrocarbon group or a hydrocarbon group having a heteroatom such as a nitrogen atom or an oxygen atom. The length of the linking group, that is, the number of atoms (not including hydrogen atoms, branched chains, or substituents) on the atomic chain present between the silicon atom of the alkoxysilyl group and the carbon atom on the triazine ring, may be, for example, 2 to 13, or 3 to 11.

An alkoxysilyl group has a structure represented by -Si(OR) ₃ . Here, R each independently represents a hydrogen atom or an alkyl group, and at least one of the three R is an alkyl group. Of the three R, it is preferable that two or more are alkyl groups, and it is more preferable that all three are alkyl groups. The alkyl groups represented by R are each independently preferably an alkyl group having 1 to 4 carbon atoms, more preferably an ethyl group or a methyl group, and even more preferably an ethyl group.

The substituents other than the monovalent group having an alkoxysilyl group that may be bonded to the triazine ring are not particularly limited, and examples thereof include halogen atoms, amino groups, hydroxy groups, arylamino groups, and alkylamino groups. Among these, amino groups are preferred, primary amino groups or secondary amino groups are more preferred, and primary amino groups are even more preferred. The number of substituents other than the monovalent group having an alkoxysilyl group is not particularly limited, and it is preferable that the number of monovalent groups having an alkoxysilyl group and the number of substituents other than the monovalent group having an alkoxysilyl group are 3 in total.

A preferred example of the first triazine ring-containing compound is a compound represented by the following general formula (I):

In formula (I), X represents a monovalent group having an alkoxysilyl group. The details of the monovalent group having an alkoxysilyl group in X are the same as those in the above-mentioned embodiment.

The molecular weight of the triazine ring-containing compound is not particularly limited and may be, for example, 100 to 800, 200 to 700, or 300 to 600.

The melting point of the first triazine ring-containing compound is not particularly limited, and from the viewpoint of high-temperature adhesion and pot life, it is preferably 200°C or less, more preferably 175°C or less, and even more preferably 150°C or less. From the viewpoint of handleability and dispersibility, the melting point of the first triazine ring-containing compound is preferably 0°C or more, more preferably 10°C or more, and even more preferably 25°C or more. From the above viewpoints, the melting point of the first triazine ring-containing compound is preferably 0°C to 200°C, more preferably 10°C to 175°C, and even more preferably 25°C to 150°C.

From the viewpoint of achieving both high-temperature adhesion to copper and an excellent pot life, the content of the first triazine ring-containing compound relative to the total mass of the underfill material is preferably 0.05 mass % or more, more preferably 0.10 mass % or more, and even more preferably 0.20 mass % or more.
Furthermore, from the viewpoint of suppressing an increase in the viscosity of the underfill material itself, the content of the first triazine ring-containing compound relative to the total mass of the underfill material is preferably 3.0 mass% or less, more preferably 2.0 mass% or less, and even more preferably 1.5 mass% or less.
From the above viewpoints, the content of the first triazine ring-containing compound relative to the total mass of the underfill material is preferably 0.05 mass% to 3.0 mass%, more preferably 0.10 mass% to 2.0 mass%, and even more preferably 0.20 mass% to 1.5 mass%.

--Second triazine ring-containing compound--
The second triazine ring-containing compound has a triazine ring and a primary amino group, and has a melting point of 200° C. or lower.

From the viewpoints of high-temperature adhesion and pot life, the melting point of the second triazine ring-containing compound is preferably 175° C. or lower, and more preferably 150° C. or lower. From the viewpoints of handleability and dispersibility, the melting point of the second triazine ring-containing compound is preferably 0° C. or higher, more preferably 10° C. or higher, and even more preferably 25° C. or higher. From the above viewpoints, the melting point of the second triazine ring-containing compound is preferably 0° C. to 200° C., more preferably 10° C. to 175° C., and even more preferably 25° C. to 150° C.
The melting point of the triazine ring-containing compound can be measured using a melting point measuring device or the like.

The position of the nitrogen in the triazine ring is not particularly limited. That is, the triazine skeleton may be any of 1,2,3-triazine, 1,2,4-triazine, and 1,3,5-triazine.

The second triazine ring-containing compound has a structure in which at least one of the hydrogen atoms bonded to three carbon atoms on triazine (C ₃ H ₃ N ₃ ) is substituted with a monovalent group having a primary amino group. The substitution position of the monovalent group may be any one of the three carbon atoms. The number of substitutions of the monovalent group may be any one from 1 to 3.

When the number of substitutions of the monovalent group having a primary amino group in the second triazine ring-containing compound is 1 or 2, the carbon atom on the triazine ring to which the monovalent group having the primary amino group is not bonded may be bonded with a substituent other than the monovalent group having the primary amino group, or may not be bonded with a substituent.

The monovalent group having a primary amino group may be the primary amino group itself, or may be a monovalent group formed by bonding a linking group to the nitrogen atom of the primary amino group. When the monovalent group having a primary amino group is a monovalent group formed by bonding a linking group to the nitrogen atom of the primary amino group, the linking group may be, for example, a hydrocarbon group, or may be a hydrocarbon group having a heteroatom such as a nitrogen atom or an oxygen atom. The length of the linking group, that is, the number of atoms (not including hydrogen atoms, branched chains, or substituents) on the atomic chain present between the nitrogen atom of the primary amino group and the carbon atom on the triazine ring, may be, for example, 1 to 10, or 1 to 5. It is preferable that the monovalent group having a primary amino group is the primary amino group itself.

The substituents other than the monovalent group having a primary amino group that may be bonded to the triazine ring are not particularly limited, and examples thereof include halogen atoms, amino groups, hydroxy groups, arylamino groups, alkylamino groups, and monovalent groups having an alkoxysilyl group. From the viewpoint of pot life, the monovalent group having an alkoxysilyl group is preferred. The details of the monovalent group having an alkoxysilyl group are the same as those of the monovalent group having an alkoxysilyl group described in the first triazine ring-containing compound. The number of the substituents other than the monovalent group having a primary amino group is not particularly limited, and it is preferable that the number of the monovalent group having a primary amino group and the number of the substituents other than the monovalent group having a primary amino group are 3 in total.

A preferred example of the second triazine ring-containing compound is the compound represented by the general formula (I) described above.

From the viewpoint of achieving both high-temperature adhesion to copper and an excellent pot life, the content of the second triazine ring-containing compound relative to the total mass of the underfill material is preferably 0.05 mass % or more, more preferably 0.10 mass % or more, and even more preferably 0.20 mass % or more.
Furthermore, from the viewpoint of suppressing an increase in the viscosity of the underfill material itself, the content of the second triazine ring-containing compound relative to the total mass of the underfill material is preferably 3.0 mass% or less, more preferably 2.0 mass% or less, and even more preferably 1.5 mass% or less.
From the above viewpoints, the content of the second triazine ring-containing compound relative to the total mass of the underfill material is preferably 0.05% by mass to 3.0% by mass, more preferably 0.10% by mass to 2.0% by mass, and even more preferably 0.20% by mass to 1.5% by mass.

<Various additives>
In addition to the above-mentioned components, the underfill material may contain various additives such as a curing accelerator, a stress relaxation agent, a coupling agent, an ion trapping agent, a bleed suppressant, a colorant, etc. In addition to the additives exemplified below, the underfill material may contain various additives known in the art as necessary.

(Cure Accelerator)
The underfill material may contain a curing accelerator. The type of the curing accelerator is not particularly limited and can be selected according to the types of epoxy resin and curing agent, the desired properties of the underfill material, etc. Specifically, cycloamidine compounds such as 1,8-diaza-bicyclo[5.4.0]undecene-7, 1,5-diaza-bicyclo[4.3.0]nonene, and 5,6-dibutylamino-1,8-diaza-bicyclo[5.4.0]undecene-7; cycloamidine compounds containing maleic anhydride, 1,4-benzoquinone, 2,5-toluquinone, 1,4-naphthoquinone, 2,3-dimethylbenzoquinone, 2,6-dimethylbenzoquinone, 2,3-dimethoxy-5-methyl-1,4-benzoquinone, 2,3-dimethoxy- Compounds having intramolecular polarization obtained by adding quinone compounds such as 1,4-benzoquinone and phenyl-1,4-benzoquinone, compounds having a π bond such as diazophenylmethane and phenol resin; tertiary amine compounds such as benzyldimethylamine, triethanolamine, dimethylaminoethanol and tris(dimethylaminomethyl)phenol; derivatives of tertiary amine compounds; 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-ethyl-4-methylimidazole imidazole compounds such as 2-phenyl-4-methyl-5-hydroxymethylimidazole and 2-phenyl-4,5-dihydroxymethylimidazole; derivatives of imidazole compounds; organic phosphine compounds such as tributylphosphine, methyldiphenylphosphine, triphenylphosphine, tris(4-methylphenyl)phosphine, diphenylphosphine, and phenylphosphine; phosphorus compounds having intramolecular polarization obtained by adding a compound having a π bond such as maleic anhydride, the above-mentioned quinone compound, diazophenylmethane, and phenol resin to an organic phosphine compound; tetraphenylborate salts such as tetraphenylphosphonium tetraphenylborate, triphenylphosphonium tetraphenylborate, 2-ethyl-4-methylimidazolium tetraphenylborate, and N-methylmorpholinium tetraphenylborate; derivatives of tetraphenylborate salts; tetraphenylborane complexes such as triphenylphosphine-triphenylborane complex and morpholine-triphenylborane complex. The curing accelerator may be used alone or in combination of two or more.

When the underfill material contains a curing accelerator, the content of the curing accelerator is not particularly limited, but is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.8 to 5 parts by mass per 100 parts by mass of epoxy resin.

(Stress Relief Agent)
The underfill material may contain a stress relaxation agent. The type of stress relaxation agent is not particularly limited, and examples include particles of thermoplastic elastomer, NR (natural rubber), NBR (acrylonitrile-butadiene rubber), acrylic rubber, urethane rubber, silicone rubber, etc. The stress relaxation agent may be used alone or in combination of two or more types.

When the underfill material contains a stress relaxation agent, the content of the stress relaxation agent is not particularly limited, but is preferably 0.1 to 30 parts by mass, and more preferably 1 to 15 parts by mass, per 100 parts by mass of epoxy resin.

(Coupling Agent)
The underfill material may contain a coupling agent. The type of coupling agent is not particularly limited, and examples thereof include silane compounds such as epoxysilane, mercaptosilane, aminosilane, alkylsilane, ureidosilane, and vinylsilane; titanium compounds; aluminum chelate compounds; and aluminum/zirconium compounds. The coupling agents may be used alone or in combination of two or more.

When the underfill material contains a coupling agent, the content of the coupling agent is not particularly limited, but is preferably 0.01 to 5 parts by mass, and more preferably 0.02 to 2.5 parts by mass, per 100 parts by mass of epoxy resin.

(Ion trapping agent)
The underfill material may contain an ion trapping agent. The type of the ion trapping agent is not particularly limited, and examples thereof include compounds represented by the following general formula (VI-1) or (VI-2).

Mg _1-a Al _a (OH) ₂ (CO ₃ ) _a/2・uH ₂ O (VI-1)
(In general formula (VI-1), a is 0<a≦0.5, and u is a positive number.)
BiO _b (OH) _c (NO ₃ ) _d (VI-2)
(In the general formula (VI-2), b is 0.9≦b≦1.1, c is 0.6≦c≦0.8, and d is 0.2≦d≦0.4.)

Ion trapping agents are commercially available. An example of a compound represented by general formula (VI-1) is "DHT-4A" (trade name, manufactured by Kyowa Chemical Industry Co., Ltd.). An example of a compound represented by general formula (VI-2) is "IXE500" (trade name, manufactured by Toagosei Co., Ltd.).

Other examples of ion trapping agents include hydrous oxides of elements selected from magnesium, aluminum, titanium, zirconium, antimony, etc. The ion trapping agents may be used alone or in combination of two or more.

When the underfill material contains an ion trapping agent, the content of the ion trapping agent is not particularly limited, and from the viewpoint of realizing sufficient moisture resistance reliability, it is preferably 1 part by mass or more, and more preferably 2 parts by mass or more, per 100 parts by mass of epoxy resin. From the viewpoint of fully exerting the effects of other components, the content of the ion trapping agent is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, per 100 parts by mass of epoxy resin. From the above viewpoints, the content of the ion trapping agent is preferably 1 part by mass to 15 parts by mass, more preferably 1 part by mass to 10 parts by mass, and even more preferably 2 parts by mass to 5 parts by mass, per 100 parts by mass of epoxy resin.

The average particle size of the ion trapping agent is preferably 0.1 μm to 3.0 μm, and the maximum particle size is preferably 10 μm or less. The average particle size of the ion trapping agent can be measured in the same manner as for the inorganic filler.

(Bleeding inhibitor)
The underfill material may contain a bleed inhibitor. The type of bleed inhibitor is not particularly limited, and examples thereof include nonionic surfactants, silicone-modified epoxy resins, etc. The bleed inhibitor may be used alone or in combination of two or more.

The content of the bleed inhibitor is not particularly limited, and is preferably 0.1 to 5 parts by mass, more preferably 0.2 to 2 parts by mass, and even more preferably 0.3 to 1 part by mass, per 100 parts by mass of epoxy resin.

(Coloring Agent)
The underfill material may contain a colorant. The type of colorant is not particularly limited, and examples thereof include carbon black, organic dyes, organic pigments, titanium oxide, red lead, red iron oxide, etc. The colorants may be used alone or in combination of two or more.

When the underfill material contains a colorant, the content of the colorant is not particularly limited, but is preferably 0.001 to 1 part by mass, and more preferably 0.02 to 0.5 parts by mass, relative to the total amount of the underfill material.

[Method of preparing underfill material]
The underfill material can be obtained, for example, by stirring, melting, mixing, dispersing, etc., each component, either collectively or separately, while optionally applying a heat treatment. The device for mixing, stirring, dispersing, etc., these components is not particularly limited, and examples thereof include a crusher equipped with a stirrer, a heater, etc., a three-roll mill, a ball mill, a planetary mixer, a bead mill, etc. The underfill material can be obtained by mixing and kneading each component using such a device, and degassing as necessary.

[Applications of underfill materials]
The underfill material can be used in various mounting techniques. In particular, the underfill material of the present disclosure can be suitably used as an underfill material for use in flip-chip mounting techniques, i.e., for filling gaps between a semiconductor element and a substrate that are joined by bumps or the like. The underfill material of the present disclosure can also be suitably used as an underfill material for use in flip-chip mounting techniques that use copper pillars.

The types of semiconductor element and substrate are not particularly limited and may be appropriately selected from those commonly used in the field of semiconductor packaging. There are no particular limitations on the method of filling the gap between the semiconductor element and substrate using the underfill material.

<Semiconductor Package>
The semiconductor package of the present disclosure includes a substrate, a semiconductor element disposed on the substrate, and a cured product of the underfill material of the present disclosure that encapsulates the semiconductor element.

In the semiconductor package, the types of semiconductor element and substrate are not particularly limited and may be appropriately selected from those commonly used in the field of semiconductor packages. From the viewpoint that the underfill material of the present disclosure is particularly useful, the semiconductor package is preferably a flip-chip mounting type semiconductor package, and more preferably a flip-chip mounting type semiconductor package that uses copper pillars as bumps to connect the semiconductor element and substrate.

<Semiconductor package manufacturing method>
The method for manufacturing a semiconductor package of the present disclosure includes a step of filling a gap between a substrate and a semiconductor element disposed on the substrate with the underfill material of the present disclosure, and a step of curing the underfill material.

The details of the semiconductor package are as described above. There are no particular limitations on the method of filling the gap between the semiconductor element and the substrate with the underfill material and the method of curing the underfill material after filling. For example, there is a post-insertion method in which, after connecting the semiconductor element and the substrate, the underfill material is applied to the gap between the semiconductor element and the substrate using capillary action, and then the underfill material is cured, and a pre-application method in which the underfill material is applied to at least one surface of the semiconductor element and the substrate first, and when the semiconductor element is connected to the substrate by thermocompression bonding, the connection between the semiconductor element and the substrate and the curing reaction of the underfill material are performed all at once. Methods of applying the underfill material include a casting method, a dispensing method, a printing method, and the like.

The curing conditions for the underfill material are not particularly limited, but it is preferable to heat it at 80°C to 200°C for 1 minute to 150 minutes, for example.

The above embodiments are explained in detail below using examples, but the scope of the embodiments of the present disclosure is not limited to these examples.

[Preparation of Underfill Material]
The components shown in Tables 1 and 2 were mixed in the amounts shown in the tables to prepare underfill materials. Details of each component are as follows. In Tables 1 and 2, blank spaces indicate that the component was not mixed.

Epoxy resin 1...liquid bisphenol F type epoxy resin, epoxy equivalent: 160 g/eq, product name "Epotohto YDF-8170C", Nippon Steel Chemical & Material Co., Ltd. Epoxy resin 2...triglycidyl-p-aminophenol, epoxy equivalent: 95 g/eq, product name "jER 630", Mitsubishi Chemical Corporation Epoxy resin 3...1,6-bis(glycidyloxy)naphthalene, epoxy equivalent: 143 g/eq, product name "Epicron HP-4023D", DIC Corporation

Curing agent 1...diethyltoluenediamine, trade name "jER Cure W", active hydrogen equivalent: 45 g/eq, Mitsubishi Chemical Corporation. Curing agent 2...3,3'-diethyl-4,4'-diaminodiphenylmethane, trade name "KAYAHARD A-A", active hydrogen equivalent: 63 g/eq, Nippon Kayaku Co., Ltd. Curing agent 3...3,4-dimethyl-6-(2-methyl-1-propenyl)-4-cyclohexene-1,2-dicarboxylic anhydride, trade name "YH-306", anhydrous acid equivalent: 234 g/eq, Mitsubishi Chemical Corporation. Curing agent 4...2-allylphenol-formaldehyde polycondensate, trade name "MEH-8000H", active hydrogen equivalent: 140 g/eq, Meiwa Kasei Co., Ltd.

Curing accelerator 1: Triphenylphosphine Curing accelerator 2: 2-phenyl-4-methyl-5-hydroxymethylimidazole
Ion trapping agent: Compound represented by general formula (VI-2), product name: "IXE500", Toagosei Co., Ltd. Coloring agent: Carbon black, product name: "MA-100", Mitsubishi Chemical Corporation Inorganic filler: Spherical silica whose surface is treated with an epoxy silane coupling agent, product name: "SE2200-SEJ", volume average particle size 0.6 μm, Admatechs Co., Ltd.

The following commercially available compounds were used as test compounds:

Compound 1... Triazine derivative (product name: VD-5, Shikoku Chemical Industry Co., Ltd., compound shown below, R is a divalent linking group)

Compound 2: Melamine (compound below)

Compound 3: 6-phenyl-1,3,5-triazine-2,4-diamine (compound below)

Compound 4: 3-amino-1,2,4-triazole (compound below)

Compound 5... 5-amino-1H-tetrazole (compound below)

Compound 6... 1,2,3-benzotriazole (product name: BT-120, Johoku Chemical Industry Co., Ltd., compound shown below)

Compound 7...1-[N,N-bis(2-ethylhexyl)aminomethyl]benzotriazole (product name: BT-LX, Johoku Chemical Industry Co., Ltd., compound shown below)

In Tables 1 and 2, the amount of the curing agent is shown as a mass ratio when the total mass of the curing agent is taken as 100. The amounts of the colorant, inorganic filler, and test compound are shown as the content (mass %) relative to the total mass of the underfill material. The amounts of the curing accelerator and ion trapping agent are shown in parts by mass of each component relative to a total of 100 parts by mass of the epoxy resin.
In the above underfill material, the ratio of the number of active hydrogens in the curing agent to the number of epoxy groups in the epoxy resin (number of active hydrogens in the curing agent/number of epoxy groups in the epoxy resin) is 1.0.

[Evaluation of Viscosity]
The viscosity (Pa·s) of the underfill material at 25° C. was measured using an E-type viscometer (Tokyo Keiki Co., Ltd., VISCONIC EHD model (product name)) (cone angle: 3°, rotation speed: 10 rotations/min) revolutions per minute (rpm).

[Pot life evaluation]
The underfill material was left at 25°C for 24 hours, and then the viscosity at 25°C was measured using an E-type viscometer (Tokyo Keiki Co., Ltd., VISCONIC EHD model (product name)) (cone angle 3°, rotation speed 10 revolutions per minute (rpm)) (viscosity after leaving). However, for samples that were too viscous to be measured at 10 revolutions per minute (rpm) due to high viscosity, the measurement was performed at 2.5 revolutions per minute (rpm). The pot life (%) was calculated as the viscosity increase rate after leaving for 24 hours using the following formula.
Pot life (%)={(viscosity after standing−initial viscosity)/initial viscosity}×100

[Evaluation of Adhesion Strength at 25°C or 260°C]
Adhesion strength to copper (Cu) A test piece was prepared by molding an underfill material onto the surface of a copper plate to a diameter of 3 mm and a height of 3 mm. Using a bond tester DS100 type (manufactured by DAGE), a shear stress was applied at a head speed of 50 μm/sec and at 25° C. or 260° C. to measure the strength at which the molded product peeled off from the copper plate.

The evaluation results are shown in Tables 3 and 4. In Tables 3 and 4, "-" indicates not applicable. "Not measurable" in the pot life evaluation indicates that the viscosity had increased so much that it could not be measured.

As shown in Tables 3 and 4, the underfill materials of Examples 1 to 6 containing Test Compound 1 were excellent in pot life and adhesion to copper at 260°C.
On the other hand, the underfill material of Comparative Example 1, which did not contain test compound 1, had slightly high adhesion to copper at 25° C., but poor adhesion to copper at 260° C. The underfill materials of Comparative Examples 2 to 7, which contained various test compounds, had significantly poor pot lives and poor adhesion to copper at 260° C. The underfill materials of Comparative Examples 8 and 9, which contained test compound 1 but in which the curing agent was replaced with curing agent 3 or 4, also had poor pot lives and poor adhesion to copper at 260° C.

The disclosure of Japanese Patent Application No. 2020-009238 is incorporated herein by reference in its entirety.
All publications, patent applications, and technical standards mentioned in this specification are incorporated by reference into this specification to the same extent as if each individual publication, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims (12)

Epoxy resin,
a curing agent comprising an aromatic amine curing agent;
An inorganic filler;
a compound having a triazine ring and an alkoxysilyl group;
Contains
The underfill material , wherein the aromatic amine curing agent comprises at least one selected from the group consisting of substituted or unsubstituted diaminodiphenylmethane and diethyltoluenediamine . The underfill material according to claim 1, wherein the compound having a triazine ring and an alkoxysilyl group has a melting point of 200°C or less. The underfill material according to claim 1 or 2, wherein the compound having a triazine ring and an alkoxysilyl group further has a primary amino group. The underfill material according to any one of claims 1 to 3, wherein the content of the compound having a triazine ring and an alkoxysilyl group is 0.05% by mass to 1.5% by mass with respect to the total mass of the underfill material. The underfill material according to any one of claims 1 to 4, wherein a ratio of the number of functional groups in the curing agent to the number of epoxy groups in the epoxy resin (number of functional groups in the curing agent/number of epoxy groups in the epoxy resin) is 0.5 to 2.0. The underfill material according to any one of claims 1 to 5, further comprising an inorganic filler in an amount of 30 mass % or more based on the total mass of the underfill material. Epoxy resin,
a curing agent comprising an aromatic amine curing agent;
An inorganic filler;
a compound having a triazine ring and a primary amino group and having a melting point of 200° C. or lower;
Contains
The underfill material , wherein the aromatic amine curing agent comprises at least one selected from the group consisting of substituted or unsubstituted diaminodiphenylmethane and diethyltoluenediamine . 8. The underfill material according to claim 7, wherein the content of the compound having a triazine ring and a primary amino group and having a melting point of 200° C. or lower is 0.05% by mass to 1.5% by mass with respect to the total mass of the underfill material. 9. The underfill material according to claim 7, wherein a ratio of the number of functional groups in the curing agent to the number of epoxy groups in the epoxy resin (number of functional groups in the curing agent/number of epoxy groups in the epoxy resin) is 0.5 to 2.0. The underfill material according to any one of claims 7 to 9, further comprising an inorganic filler in an amount of 30 mass % or more based on the total mass of the underfill material. A semiconductor package comprising: a substrate; a semiconductor element disposed on the substrate; and a cured product of the underfill material according to any one of claims 1 to 10 , which seals the semiconductor element. A method for manufacturing a semiconductor package, comprising: a step of filling a gap between a substrate and a semiconductor element disposed on the substrate with the underfill material according to any one of claims 1 to 10 ; and a step of hardening the underfill material.