Epoxy resin composition for encapsulation and semiconductor device

Abstract

The present invention provides an epoxy resin composition for sealing that exhibits excellent fluidity and reactivity during curing, and further suppresses the amount of undissolved curing accelerator. [Solution] The epoxy resin composition for sealing contains an epoxy compound (A), a curing agent (B), an inorganic filler (C), and a phosphonium salt (d1) represented by formula (1). In formula (1), R1, R2, and R3 are each independently aryl groups having 6 to 12 carbon atoms. R4 is an alkyl group having 1 to 4 carbon atoms. R5 and R7 are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms. R6 is a hydroxyl group or a carboxyl group. R8 is an aromatic ring, and the hydroxyl group bonded to R8 is bonded to two adjacent carbon atoms in R8. a is a number between 1 and 10. TIFF2026104698000012.tif41170

Description

Technical Field

[0001] The present disclosure relates to an epoxy resin composition for encapsulation and a semiconductor device.

Background Art

[0002] Patent Document 1 discloses an epoxy resin composition for encapsulation containing a phosphonium salt having a specific structure, an epoxy resin, a curing agent, and an inorganic filler.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The inventor has completed the present disclosure in order to further improve the performance of the epoxy resin composition for encapsulation disclosed in Patent Document 1.

[0005] An object of the present disclosure is to provide an epoxy resin composition for encapsulation that is excellent in fluidity and reactivity during curing, and further suppresses the melting residue of the curing accelerator, and a semiconductor device encapsulated with this epoxy resin composition for encapsulation.

Means for Solving the Problems

[0006] The epoxy resin composition for encapsulation according to one aspect of the present disclosure contains an epoxy compound (A), a curing agent (B), an inorganic filler (C), and a phosphonium salt (d1) represented by the formula (1).

[0007]

Chemical Formula

[0008] In formula (1), R1, R2, and R3 are each independently aryl groups having 6 to 12 carbon atoms. R4 is an alkyl group having 1 to 4 carbon atoms. R5 and R7 are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms. R6 is a hydroxyl group or a carboxyl group. R8 is an aromatic ring, and the hydroxyl group bonded to R8 is bonded to two adjacent carbon atoms in R8. a is a number between 1 and 10.

[0009] A semiconductor device according to one aspect of the present disclosure comprises a semiconductor element and a sealing portion that seals the semiconductor element. The sealing portion includes a cured product of the sealing epoxy resin composition. [Effects of the Invention]

[0010] According to this disclosure, it is possible to provide an epoxy resin composition for encapsulation that exhibits excellent fluidity and reactivity during curing, and further suppresses residual dissolution of the curing accelerator, as well as a semiconductor device encapsulated with this epoxy resin composition. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic cross-sectional view of a semiconductor device in one embodiment of the present disclosure. [Modes for carrying out the invention]

[0012] Embodiments of this disclosure will now be described. Note that the embodiments described below are only a selection of the various embodiments of this disclosure. Furthermore, the embodiments described below can be modified in various ways depending on the design, etc., as long as the objectives of this disclosure are achieved. The figures referenced below are schematic diagrams, and the dimensional ratios of the components in the figures do not necessarily reflect the actual dimensional ratios. The mechanisms of operation described below are inferred, and this disclosure is not bound by the following explanation of the mechanisms of operation.

[0013] 1. Overview The epoxy resin composition for sealing of the embodiment (hereinafter, also referred to as composition (X)) contains an epoxy compound (A), a curing agent (B), an inorganic filler (C), and a phosphonium salt (d1) represented by the formula (1).

[0014]

Chemical formula

[0015] In the formula (1), R1, R2 and R3 are each independently an aryl group having 6 to 12 carbon atoms. R4 is an alkyl group having 1 to 4 carbon atoms. R5 and R7 are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms. R6 is a hydroxyl group or a carboxyl group. R8 is an aromatic ring, and the hydroxyl groups bonded to R8 are each bonded to two adjacent carbon atoms in R8. a is a number from 1 to 10.

[0016] According to the embodiment, the composition (X) is excellent in fluidity and reactivity during curing, and further the melt residue of the curing accelerator can be suppressed.

[0017] 2. Details The details of the composition (X) will be described.

[0018] The composition (X) contains an epoxy compound (A), a curing agent (B), an inorganic filler (C), and a curing accelerator (D).

[0019] The epoxy compound (A) is a compound having two or more epoxy groups in one molecule. The epoxy compound (A) may contain at least one selected from the group consisting of, for example, bisphenol A type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin (a1), biphenyl aralkyl type epoxy resin (a2), and triphenylmethane type epoxy resin. In particular, it is preferable for the epoxy compound (A) to contain at least one selected from the group consisting of biphenyl type epoxy resin (a1) and biphenyl aralkyl type epoxy resin (a2) in order to improve the reliability of the semiconductor device. The epoxy equivalent of the epoxy compound (A) is preferably 150 to 290. The softening point or melting point of the epoxy compound (A) is preferably 50°C to 130°C.

[0020] The curing agent (B) acts as a curing agent for the epoxy compound (A). Preferably, the curing agent (B) contains at least one selected from the group consisting of phenol compounds, acid anhydrides, and functional compounds that generate phenolic hydroxyl groups. In particular, if the curing agent (B) contains at least one of a phenol compound and a functional compound, very high moisture resistance reliability can be imparted to the sealing portion made from composition (X).

[0021] Phenolic compounds can include monomers, oligomers, and polymers having two or more phenolic hydroxyl groups in one molecule. For example, the curing agent (B) can contain at least one selected from the group consisting of phenolic novolak resins, cresol novolak resins, biphenyl-type novolak resins, triphenylmethane-type resins, naphthol novolak resins, phenol aralkyl resins, and biphenyl aralkyl resins. In particular, it is preferable for improving the reliability of semiconductor devices that the curing agent (B) contains at least one of a phenol aralkyl resin and a biphenyl aralkyl resin with low hygroscopicity. When the curing agent (B) is a phenolic compound, the equivalent of the hydroxyl group of the phenolic compound per equivalent of the epoxy group of the epoxy compound (A) is preferably 0.5 or more and 2.0 or less, and more preferably 0.8 or more and 1.4 or less.

[0022] The acid anhydride can contain at least one selected from the group consisting of phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, benzophenone tetracarboxylic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and polyazelainic anhydride. When the curing agent (B) is an acid anhydride, the equivalent converted to the carboxyl group of the acid anhydride group per equivalent of the epoxy group of the epoxy compound (A) is preferably 0.7 or more and 1.5 or less, and more preferably 0.8 or more and 1.2 or less.

[0023] Examples of the functional compound that generates a phenolic hydroxyl group include a compound that generates a phenolic hydroxyl group when heated. More specifically, examples of the functional compound include benzoxazines that open a ring when heated to generate a phenolic hydroxyl group.

[0024] The inorganic filler (C) can contain materials generally incorporated into epoxy resin compositions without particular limitations. For example, the inorganic filler (C) may contain molten silica powder, spherical silica powder, crushed silica powder, crystalline silica powder, spherical alumina powder, magnesium oxide powder, boron nitride powder, aluminum nitride powder, etc.; high dielectric constant fillers such as barium titanate powder and titanium oxide powder; magnetic fillers such as hard ferrite powder; inorganic flame retardants such as magnesium hydroxide powder, aluminum hydroxide powder, antimony trioxide powder, antimony pentoxide powder, guanidine salt powder, zinc borate powder, molybdenum compound powder, and zinc stanate powder; and at least one selected from the group consisting of talc powder, barium sulfate powder, calcium carbonate powder, mica powder, etc. In particular, it is preferable that the inorganic filler (C) contains spherical molten silica powder. The average particle size of the inorganic filler (C) is preferably 1 μm or more and 40 μm or less, in which case the fluidity of the composition (X) during molding is particularly good. The average particle size is the median diameter calculated from the volume-based particle size distribution measured by a laser diffraction scattering particle size distribution analyzer. An average particle size of 3 μm or larger is more preferable.

[0025] The amount of inorganic filler (C) is preferably 200 parts by mass or more and 1200 parts by mass or less, relative to 100 parts by mass of the total of epoxy compound (A) and curing agent (B). If the amount of inorganic filler (C) is 200 parts by mass or more, the melt viscosity of composition (X) during molding is suppressed to be excessively low, which can suppress appearance defects such as voids in the sealing part made from composition (X). It is more preferable if the amount of inorganic filler (C) is 300 parts by mass or more, even more preferable if it is 450 parts by mass or more, and particularly preferable if it is 500 parts by mass or more. If the amount of inorganic filler (C) is 1200 parts by mass or less, the fluidity of composition (X) during molding is particularly increased, which can suppress defects such as wire flow and incomplete filling. It is more preferable if the amount of inorganic filler (C) is 750 parts by mass or less, even more preferable if it is 700 parts by mass or less, and particularly preferable if it is 500 parts by mass or less.

[0026] The curing accelerator (D) in composition (X) contains a phosphonium salt (d1) shown in formula (1).

[0027] Phosphonium salt (d1) is composed of a quaternary phosphonium cation, an organic carboxylate anion, and an aromatic compound. In phosphonium salt (d1), the quaternary phosphonium cation and the organic carboxylate anion are ionically bonded. Furthermore, the organic carboxylate anion and the aromatic compound are hydrogen bonded, and therefore phosphonium salt (d1) is a complex compound. An example of a conceptual model of the structure of this phosphonium salt (d1) is shown in equation (2) below. In equation (2), Me represents a methyl group.

[0028] [ka]

[0029] The phosphonium salt (d1) can improve the fluidity and curability of composition (X). This is thought to be due to the following interactions between the three elements constituting the phosphonium salt (d1): a quaternary phosphonium cation, an organic carboxylate anion, and an aromatic compound.

[0030] In the phosphonium salt (d1), the organic carboxylate anion has a carbonyl group and a carboxylate group, which are substituents capable of hydrogen bonding, at the 1 and 3 positions, and the aromatic compound has a hydroxyl group, which is a substituent capable of hydrogen bonding, at the 1 and 2 positions. A strong hydrogen bonding interaction acts between the organic carboxylate anion and the aromatic compound. This makes the acid strength of the organic carboxylate anion appear stronger, making it difficult for the organic carboxylate anion and the phosphonium salt to dissociate. Therefore, at room temperature, the state in which the quaternary phosphonium cation and the organic carboxylate anion in the phosphonium salt (d1) do not dissociate is maintained, thereby suppressing the curing of the encapsulating epoxy resin composition. For this reason, composition (X) is considered to have excellent storage stability.

[0031] Even when composition (X) is heated, the strong interaction between the organic carboxylate anion and the aromatic compound is initially maintained, suppressing the dissociation of the quaternary phosphonium cation and the organic carboxylate anion. Therefore, even when composition (X) is heated, the curing reaction does not proceed immediately, and the increase in the melt viscosity of composition (X) is suppressed. As a result, composition (X) is expected to have excellent fluidity during molding.

[0032] After heating begins, the interaction between the organic carboxylate anion and the aromatic compound gradually weakens, and the quaternary phosphonium cation and the organic carboxylate anion dissociate. This accelerates the curing of composition (X). Therefore, it is believed that high fluidity and curability can be achieved simultaneously.

[0033] In this embodiment, the aromatic compound has hydroxyl groups, which are substituents capable of hydrogen bonding, on two adjacent carbon atoms on the aromatic ring, which allows composition (X) to achieve particularly excellent fluidity during molding. This is presumed to be because the two adjacent hydroxyl groups form a chelate structure with the quaternary phosphonium cation, thereby stabilizing the cation.

[0034] In this embodiment, in formula (1), R1 to R3 are each independently aryl groups having 6 to 12 carbon atoms. Having 12 or fewer carbon atoms in the aryl group reduces steric hindrance between the quaternary phosphonium cation and the organic carboxylate anion in the phosphonium salt (d1), and the moderate electron-donating properties of the aryl group contribute to the high stability of the phosphonium salt (d1). The number of carbon atoms in the aryl group is more preferably 10 or less, and even more preferably 8 or less.

[0035] Since R6 is a hydroxyl group or a carboxyl group, the curing reaction is particularly accelerated by aromatic compounds. Furthermore, the formation of a three-dimensional crosslinked structure in the resin skeleton generated by the curing reaction can improve the glass transition temperature of the cured product. In addition, the strong interaction between the organic carboxylate anion and the aromatic compound can result in excellent storage stability, excellent fluidity during molding, and excellent curability of composition (X).

[0036] Furthermore, in organic carboxylate anions, the functional groups that react with the epoxy compound on the aromatic ring are not adjacent to each other, thus suppressing steric hindrance around the functional groups. In addition, R5 and R7 are each independently hydrogen or alkyl groups having 1 to 4 carbon atoms, which also suppresses steric hindrance around the functional groups that react with the epoxy compound on the aromatic ring. As a result, the probability of functional groups that react with the epoxy compound remaining unreacted when composition (X) cures is reduced, and composition (X) is given high cured product properties. The fewer carbon atoms in the alkyl group, the better, and hydrogen is more preferable than alkyl groups.

[0037] Furthermore, the phosphonium salt (d1) does not contain benzene, and benzene is not generated during the synthesis of the phosphonium salt (d1) and mixed into the phosphonium salt (d1). Therefore, the release of benzene from composition (X) originating from the curing accelerator is suppressed.

[0038] Furthermore, when preparing composition (X) by heating and kneading the raw materials, the phosphonium salt (d1) disperses and melts easily in composition (X). That is, undissolved phosphonium salt (d1) is less likely to occur in composition (X) and the cured product. This is thought to be because the dispersibility of the phosphonium salt (d1) in composition (X) is enhanced by some intermolecular interaction. Therefore, when encapsulating semiconductor devices with composition (X), the occurrence of phosphonium salt (d1) particles getting caught between wires or bumps and causing insulation failure is suppressed. In the embodiment, in particular, when preparing the phosphonium salt (d1), if an aromatic compound having a hydroxyl group that is poorly soluble on its own is dissolved with a quaternary phosphonium cation, an organic carboxylate anion, and a phenol compound which is the curing agent (B) in composition (X), the phosphonium salt (d1) disperses and melts particularly easily in composition (X).

[0039] In aromatic ring compounds, the aromatic ring R8 is, for example, a benzene ring, or a condensed ring such as a naphthalene ring, anthracene ring, or phenanthrene ring. Preferably, R8 has no substituents other than the two hydroxyl groups, but it may have further substituents other than the two hydroxyl groups as long as they do not excessively inhibit the action of the phosphonium salt (d1).

[0040] Furthermore, if a in formula (1) is 1 or greater, the dissociation of the quaternary phosphonium cation and the organic carboxylate anion at the beginning of heating of composition (X) can be further suppressed. Also, if a is 10 or less, excessive catalytic activity after dissociation can be suppressed, and problems such as an increase in the amount of chlorine due to the reaction can be suppressed. It is more preferable if a is 2 or greater. It is even more preferable if a is 7 or less, and even more preferable if a is 4 or less.

[0041] Phosphonium salts (d1) can be synthesized, for example, by a salt exchange reaction between an alkyl carbonate of a quaternary phosphonium corresponding to a quaternary phosphonium cation and an organic carboxylic acid corresponding to an organic carboxylate anion. This intermediate is then synthesized by mixing the intermediate with an aromatic compound. However, the synthesis method for phosphonium salts (d1) is not limited to the above.

[0042] The amount of phosphonium salt (d1) is preferably 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the total of epoxy compound (A) and curing agent (B). If the amount of phosphonium salt (d1) is 1 part by mass or more, composition (X) may be imparted with particularly excellent curability. If the amount of phosphonium salt (d1) is 1.5 parts by mass or more, it is more preferable, and if it is 2 parts by mass or more, it is even more preferable. If the amount of phosphonium salt (d1) is 10 parts by mass or less, composition (X) may be imparted with particularly excellent fluidity during molding. If the amount of phosphonium salt (d1) is 7 parts by mass or less, it is more preferable, and if it is 5 parts by mass or less, it is even more preferable.

[0043] The curing accelerator (D) in composition (X) may contain only a phosphonium salt (d1), or it may further contain a curing accelerator (d2) other than the phosphonium salt (d1). The curing accelerator (d2) may contain at least one selected from the group consisting of, for example, triarylphosphines, tetraphenylphosphonium-tetraphenylborate, imidazoles such as 2-methylimidazole, and 1,8-diazabicyclo(5,4,0)undecene-7.

[0044] When the curing accelerator (D) contains a phosphonium salt (d1) and a curing accelerator other than the phosphonium salt (d2), the amount of curing accelerator (D) is preferably more than 1 part by mass and 10 parts by mass or less, based on 100 parts by mass of the total of the epoxy compound (A) and the curing agent (B). Furthermore, the ratio of the curing accelerator other than the phosphonium salt (d1) (d2) to the curing accelerator (D) is preferably 50% by mass or less.

[0045] Composition (X) may further contain additives other than epoxy compounds (A), curing agents (B), inorganic fillers (C), and curing accelerators (D), as needed. The additives include, for example, at least one selected from the group consisting of release agents (E), coupling agents (F), ion trapping agents (G), flame retardants, flame retardant aids, pigments, colorants, stress reducers, tackifiers, and silicone flexible agents.

[0046] The release agent (E) may contain, for example, higher fatty acids, higher fatty acid esters, or higher fatty acid calcium. For example, the release agent (E) may contain at least one selected from the group consisting of carnauba wax and polyethylene-based wax.

[0047] The coupling agent (F) can further enhance the fluidity of composition (X). The coupling agent (F) may include, for example, a silane coupling agent. The silane coupling agent preferably has two or more alkoxy groups. The silane coupling agent may contain at least one selected from the group consisting of, for example, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-anilinopropyltrimethoxysilane, and hexamethyldisilazane.

[0048] The ion trapping agent (G) can improve the reliability of semiconductor devices. The ion trapping agent may contain known compounds that have ion trapping capabilities. For example, the ion trapping agent may contain at least one selected from the group consisting of hydrotalcites and bismuth hydroxide.

[0049] The flame retardant may contain, for example, a novolac-type brominated epoxy resin or a metal hydroxide. In particular, it is preferable that the flame retardant contains at least one selected from the group consisting of antimony trioxide and antimony pentoxide.

[0050] The stress-reducing agent (plasticizer) may contain at least one selected from the group consisting of, for example, butadiene rubbers such as methyl acrylate-butadiene-styrene copolymer and methyl methacrylate-butadiene-styrene copolymer, and silicone compounds.

[0051] A method for producing composition (X) will be described. An epoxy compound (A), a curing agent (B), an inorganic filler (C), and a curing accelerator (D), along with additives as needed, are mixed together. The mixture is then melted and mixed under heating using a kneader such as a hot roll or kneader, followed by cooling to room temperature and further pulverization to obtain a powdered composition (X). This powdered composition (X) may be compressed into tablets to obtain a tablet-shaped composition (X) having dimensions and mass suitable for the molding conditions.

[0052] Composition (X) is suitable for creating a sealing portion for sealing semiconductor elements in a semiconductor device.

[0053] An example of a semiconductor device 1 having a sealing portion 62 containing a cured product of composition (X), and an example of a method for manufacturing the same will be described.

[0054] The semiconductor device 1 is an insert-type package such as Mini, D-pack, D2-pack, To22O, To3P, or Dual In-Line Package (DIP), or a surface-mount package such as Quad Flat Package (QFP), Small Outline Package (SOP), Small Outline J-Lead Package (SOJ), Plastic Ball Grid Array (PBGA), Fine Pitch Ball Grid Array (FBGA), Wafer Level Package (WLP), Panel Level Package (PLP), Fan-Out Wafer Level Package (FO-WLP), or Fan-Out Panel Level Package (FO-PLP).

[0055] Figure 1 shows a cross-sectional view of an example of a semiconductor device 1 in an embodiment. This semiconductor device 1 comprises a metal lead frame 52, a semiconductor element 50 mounted on the lead frame 52, wires 56 that electrically connect the semiconductor element 50 and the lead frame 52, and a sealing portion 62 that seals the semiconductor element 50.

[0056] The lead frame 52 comprises a die pad 58, an inner lead 521, and an outer lead 522. The lead frame 52 is made of, for example, copper or an iron alloy such as 42 alloy. Preferably, the lead frame 52 comprises a main body 53 made of copper or an iron alloy such as 42 alloy, and a plating layer 54 covering the main body 53. In this case, corrosion of the lead frame 52 is suppressed. Preferably, the plating layer 54 contains at least one component from silver, nickel, and palladium. The plating layer 54 may contain only one metal from silver, nickel, and palladium, or it may contain an alloy containing at least one metal from silver, nickel, and palladium. The plating layer 54 may have a laminated structure, specifically, for example, a laminated structure consisting of a palladium layer, a nickel layer, and a gold layer. The thickness of the plating layer 54 is, for example, 1 μm or more and 20 μm or less, but is not particularly limited thereto.

[0057] The semiconductor element 50 is fixed onto the die pad 58 of the lead frame 52 with an appropriate die bond material 60. This mounts the semiconductor element 50 onto the lead frame 52. The semiconductor element 50 is, for example, an integrated circuit, a large-scale integrated circuit, a transistor, a thyristor, a diode, or a solid-state image sensor. The semiconductor element 50 may also be a novel power device such as SiC or GaN.

[0058] Next, the semiconductor element 50 and the inner lead 521 in the lead frame 52 are connected with a wire 56. The wire 56 may be made of gold, but may also contain at least one of copper and silver. For example, the wire 56 may be made of silver or copper. If the wire 56 contains at least one of copper and silver, the wire 56 may be coated with a thin film of a metal such as palladium.

[0059] Next, the composition (X) is molded to create a sealing portion 62 that seals the semiconductor element 50. The sealing portion 62 also seals the wire 56. The sealing portion 62 also seals the die pad 58 and the inner lead 521, and therefore the sealing portion 62 is in contact with the lead frame 52, and if the lead frame 52 has a plating layer 54, it is in contact with the plating layer 54.

[0060] It is preferable to produce the sealing portion 62 by molding composition (X) by a pressure molding method. The pressure molding method is, for example, injection molding, transfer molding, or compression molding.

[0061] The conditions for molding composition (X) by pressure molding are set appropriately according to the composition of composition (X). The molding pressure when molding composition (X) by pressure molding is, for example, 3.0 MPa or higher, and the molding temperature is 120°C or higher.

[0062] In particular, in the case of transfer molding, the injection pressure of composition (X) into the mold is preferably 3 MPa or higher, and more preferably 4 MPa to 710 MPa. The heating temperature (mold temperature) is preferably 120°C or higher, and more preferably 160°C to 190°C. The heating time is preferably 30 seconds to 300 seconds, and more preferably 60 seconds to 180 seconds.

[0063] In the transfer molding method, it is preferable to perform post-curing by heating the sealing portion 62 in the mold while the mold is closed, after which the semiconductor device 1 is removed by opening the mold. The heating conditions for post-curing are, for example, a heating time of 160°C to 190°C and a heating time of 2 hours to 8 hours.

[0064] [Pattern] According to the embodiments described above, this disclosure includes the following aspects.

[0065] The epoxy resin composition for sealing according to the first embodiment contains an epoxy compound (A), a curing agent (B), an inorganic filler (C), and a phosphonium salt (d1) represented by formula (1).

[0066] [ka]

[0067] In formula (1), R1, R2, and R3 are each independently aryl groups having 6 to 12 carbon atoms. R4 is an alkyl group having 1 to 4 carbon atoms. R5 and R7 are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms. R6 is a hydroxyl group or a carboxyl group. R8 is an aromatic ring. The hydroxyl group bonded to R8 is bonded to two adjacent carbon atoms in R8. a is a number between 1 and 10.

[0068] According to this embodiment, the epoxy resin composition for sealing exhibits excellent fluidity and reactivity during curing, and furthermore, the amount of undissolved curing accelerator can be suppressed.

[0069] In the second embodiment, the amount of phosphonium salt (d1) is 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total of epoxy compound (A) and curing agent (B).

[0070] In the third embodiment, in the first or second embodiment, the amount of inorganic filler (C) is 200 parts by mass or more and 1200 parts by mass or less, relative to 100 parts by mass of the total of epoxy compound (A) and curing agent (B).

[0071] In the fourth embodiment, in any one of the first to third embodiments, the epoxy compound (A) contains at least one selected from the group consisting of biphenyl-type epoxy resins (a1) and biphenyl aralkyl-type epoxy resins (a2).

[0072] In the fifth embodiment, in any one of the first to fourth embodiments, the encapsulating epoxy resin composition further contains a release agent (E).

[0073] In the sixth embodiment, in any one of the first to fifth embodiments, the encapsulating epoxy resin composition further contains a coupling agent (F).

[0074] In the seventh embodiment, in any one of the first to sixth embodiments, the encapsulating epoxy resin composition further contains an ion trapping agent (G).

[0075] In the eighth aspect, the semiconductor device (1) comprises a semiconductor element (50) and a sealing portion (62) that seals the semiconductor element (50). The sealing portion (62) contains a cured product of an epoxy resin composition for sealing according to any one of the first to seventh aspects. [Examples]

[0076] Further specific embodiments of the embodiment are presented below. However, the embodiments are not limited to those described below.

[0077] 1. Preparation of the composition A mixture was obtained by thoroughly mixing the raw materials shown in Table 1 in a mixer. This mixture was melt-kneaded while being heated at a set temperature of 100°C for 5 minutes using a twin-screw roller, and after cooling, it was ground in a pulverizer to obtain a powdered composition.

[0078] Details of these raw materials are as follows. Note that in Table 1, the amount of raw materials is shown in parts by mass. -Epoxy compound #1: Tetramethylbiphenyl type epoxy resin. Manufactured by Mitsubishi Chemical Corporation. Product name: YX4000. -Epoxy compound #2: Biphenyl aralkyl type epoxy resin. Manufactured by Nippon Kayaku Co., Ltd. Product name: NC3000. -Phenol compound #1: Novolac-type phenolic resin. Manufactured by UBE Corporation. Part number DL-92. -Phenol compound #2: Biphenyl aralkyl type phenolic resin. Manufactured by UBE Corporation. Product name: MEH-7851-SS. - Inorganic filler: Spherical silica powder. 10% diameter (D10) 0.3 μm, 50% diameter (D50) 5 μm, 99% diameter (D99) 12 μm. -Curing accelerator #1: Phosphonium salt shown in the formula below. Manufactured by Sunapro Co., Ltd. Product name: U-CAT RP701.

[0079] [ka]

[0080] -Curing accelerator #2: A phosphonium salt shown in the following formula.

[0081] [ka]

[0082] -Curing accelerator #3: A phosphonium salt shown in the following formula.

[0083] [ka]

[0084] -Curing accelerator #4: A phosphonium salt shown in the following formula.

[0085] [ka]

[0086] -Release agent: Carnauba wax. Manufactured by Dainichi Chemical Industry Co., Ltd. Product name: F1-100. - Coupling agent: Silane coupling agent. Manufactured by Shin-Etsu Chemical Co., Ltd. Product name: KBM573. - Pigment: Carbon black. Manufactured by Mitsubishi Chemical Corporation. Product name: MA600. - Additive #1: Ion trapping agent. Manufactured by Toagosei Co., Ltd. Product name: IXE700F. -Additive #2: 2,3-dihydroxynaphthalene. Tokyo Chemical Industry Co., Ltd.

[0087] 2. Evaluation (1) Spiral flow length As an indicator of fluidity during molding, the spiral flow length of the composition immediately after manufacturing was measured using a spiral flow measurement mold compliant with ASTM D3123, under the conditions of a mold temperature of 170°C, an injection pressure of 6.9 MPa, and a molding time of 180 seconds.

[0088] (2) Geltime As an indicator of curability, the gel time of the composition at 170°C was measured. The measurement was performed using a Curlastometer III PS for 1.67 ml of the composition. In this evaluation test, gel time is defined as the time required from the start of measurement until the torque reaches 9.81 mN·m (0.1 kgf·cm).

[0089] (3) Meltability The composition was compressed into tablets to obtain tablets with a diameter of 13 mm and a thickness of 20 mm. One side of each tablet was polished eight times by 2 mm each time. After each polishing, the polished surface was observed with a metallurgical microscope. The result was evaluated as "good" if no undissolved hardening accelerator was ever observed on the polished surface, and as "poor" if any undissolved hardening accelerator was observed even once.

[0090] [Table 1]

[0091] As shown in the results above, in Examples 1 to 6, which used a curing accelerator equivalent to the phosphonium salt (d1), the evaluation of spiral flow length, gel time, and melting properties were all good. In contrast, in Comparative Example 1, which did not use a curing accelerator equivalent to the phosphonium salt (d1), the evaluation of spiral flow length was poor. Furthermore, in Comparative Example 2, which also used 2,3-dihydroxynaphthalene, the evaluation of spiral flow length improved. This is thought to be because 2,3-dihydroxynaphthalene forms a chelate structure similar to the aromatic ring compounds in curing accelerators #2 to 4. However, in Comparative Example 2, the evaluation of melting properties deteriorated. [Explanation of Symbols]

[0092] 1 Semiconductor device 50 Semiconductor elements 62 Sealing part

Claims

1. Epoxy compound (A) and, Hardener (B), Inorganic filler (C), It contains the phosphonium salt (d1) represented by formula (1), 【Chemistry 1】 In equation (1), R1, R2, and R3 are each independently aryl groups having 6 to 12 carbon atoms. R4 is an alkyl group having 1 to 4 carbon atoms. R5 and R7 are each independently hydrogen or an alkyl group having 1 to 4 carbon atoms. R6 is a hydroxyl group or a carboxyl group. R8 is an aromatic ring, and the hydroxyl group bonded to R8 is bonded to two adjacent carbon atoms on R8, a is a number between 1 and 10 (inclusive). Epoxy resin composition for sealing.

2. The amount of the phosphonium salt (d1) is 1 part by mass or more and 10 parts by mass or less, relative to 100 parts by mass of the total of the epoxy compound (A) and the curing agent (B). The epoxy resin composition for sealing according to claim 1.

3. The amount of the inorganic filler (C) is 200 parts by mass or more and 1200 parts by mass or less, relative to 100 parts by mass of the total of the epoxy compound (A) and the curing agent (B). The epoxy resin composition for sealing according to claim 1.

4. The epoxy compound (A) contains at least one selected from the group consisting of biphenyl-type epoxy resin (a1) and biphenyl aralkyl-type epoxy resin (a2). The epoxy resin composition for sealing according to claim 1.

5. Further containing a release agent (E), The epoxy resin composition for sealing according to claim 1.

6. Further containing a coupling agent (F), The epoxy resin composition for sealing according to claim 1.

7. It further contains an ion trapping agent (G), The epoxy resin composition for sealing according to claim 1.

8. Semiconductor elements and The semiconductor element comprises a sealing portion for sealing the semiconductor element, The sealing portion includes a cured product of the sealing epoxy resin composition according to any one of claims 1 to 7. Semiconductor equipment.

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