JP2643547B2 - Epoxy resin composition for semiconductor encapsulation - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an epoxy resin composition for sealing a semiconductor device. More specifically, an epoxy resin composition for semiconductor encapsulation that prevents cracks in the encapsulating resin in a soldering step when mounting a resin-encapsulated semiconductor device, particularly a semiconductor excellent in moisture resistance and moldability The present invention relates to an epoxy resin composition for sealing.

<Related Art> In recent years, in the field of semiconductor integrated circuits, technology for high integration and high reliability has been developed, and at the same time, automation of a process of assembling a semiconductor device on a wiring board has been promoted. For example, when mounting a flat package type semiconductor device on a circuit board, soldering has conventionally been performed for each lead pin, but recently, the entire semiconductor device is immersed in a solder bath heated to 250 ° C or more, and the surface is soldered. The mounting method is adopted. For this reason, a conventional package sealed with a sealing resin has a problem that cracks occur in the resin portion at the time of soldering, and the reliability is reduced and the package cannot be used as a product.

As a method for sealing a semiconductor, a method in which a semiconductor element is set in a mold and sealed by a transfer molding method or the like using a composition obtained by adding a curing agent and a filler to an epoxy resin is generally performed. Have been done.

The characteristics required for these semiconductor sealing resins include reliability, solder heat resistance, and moldability. The reliability includes moisture resistance, and the moldability includes burrs and heat hardness.

The term “moisture resistance” here means that when a resin-encapsulated semiconductor is left in a high-temperature, high-humidity environment, moisture enters through an interface between the encapsulation resin and the encapsulation resin and the lead frame,
This is to prevent a semiconductor from breaking down. In recent years, the degree of integration of semiconductors has been improved, and a higher degree of moisture resistance has been required.

In order to improve the moisture resistance of the sealing resin, a silane coupling agent is usually added. Specifically, a method of adding an epoxy silane (Japanese Patent Publication No. 62-17640) and a method of adding a vinyl silane (JP-A-62-223219, JP-A-57-155753) and the like have been proposed.

Further, as a conventional method for improving the solder crack resistance of the sealing resin, for example, a method using a biphenyl type epoxy resin (Japanese Patent Application Laid-Open No. 63-251419) has been proposed.

<Problems to be Solved by the Invention> However, in the method of adding epoxy silane or vinyl silane to improve the moisture resistance, the improvement of the moisture resistance and solder heat resistance by these additions is not yet sufficient,
It was difficult to use as a product.

Also, in the method using a biphenyl type epoxy resin and epoxy silane, the solder crack resistance of the sealing resin is improved to some extent, but not only to a satisfactory level, but also the moisture resistance is low, and the hardness when heated during molding is low. It was not practical due to problems such as many burrs.

Therefore, an object of the present invention is to solve the above-mentioned problems of the epoxy resin composition and to provide an epoxy resin composition excellent in reliability such as solder heat resistance and moisture resistance, and excellent in moldability such as burr and hot hardness. Thus, a resin-sealed semiconductor for surface mounting is made possible.

<Means for Solving the Problems> The inventors of the present invention have found that the use of a polyfunctional silane coupling agent achieves the above-mentioned problems and provides an epoxy resin composition for semiconductor encapsulation that meets the purpose. Reached the present invention.

That is, the present invention provides an epoxy resin (A) containing 30% by weight or more of an epoxy resin (a) having a skeleton represented by the following formula (I), a curing agent (B), a filler (C), and a polyfunctional silane. An epoxy resin composition for semiconductor encapsulation containing a coupling agent (D), (Where R1 to R8 are a hydrogen atom, a lower alkyl group of C1 to C4 or a halogen atom) and a semiconductor device in which a semiconductor element is encapsulated with the epoxy resin composition for encapsulating a semiconductor.

 Hereinafter, the configuration of the present invention will be described in detail.

The epoxy resin (A) in the present invention is not particularly limited as long as it has at least two epoxy groups in its molecule. Specific examples thereof include, for example, a cresol novolak epoxy resin and a phenol novolak epoxy resin. A biphenyl type epoxy resin (a) having a skeleton represented by the following formula (I): (However, R ^{1 to} R ⁸ represent a hydrogen atom, a C _{1 to} C ₄ lower alkyl group or a halogen atom.) A novolak epoxy resin represented by the following formula (II): Examples include various novolak-type epoxy resins synthesized from bisphenol A, resorcin, and the like, bisphenol A-type epoxy resins, linear aliphatic epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, and halogenated epoxy resins.

Depending on the application, two or more types of epoxy resins may be used in combination. However, for semiconductor encapsulation resins, the total epoxy resin contains 30% by weight or more of biphenyl type epoxy resin (a) from the viewpoint of solder heat resistance.

Preferred specific examples of the biphenyl type epoxy resin (a) include 4,4'-bis (2,3-epoxypropoxy) biphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,
3 ', 5,5'-tetramethylbiphenyl, 4,4'-bis (2,
3-epoxypropoxy) -3,3 ', 5,5'-tetramethyl-2-chlorobiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3', 5,5'-tetra Methyl-2-bromobiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetraethylbiphenyl and 4,
4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'
-Tetrabutylbiphenyl and the like.

The curing agent (B) in the present invention is an epoxy resin (A)
There is no particular limitation as long as it reacts and cures, and specific examples thereof include, for example, a phenol novolak resin, a cresol novolak resin, a novolak resin represented by the following formula (III), Various novolak resins synthesized from bisphenol A and resorcinol, various polyphenol compounds, acid anhydrides such as maleic anhydride, phthalic anhydride and pyromellitic anhydride, and aromatics such as metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone Amines and the like. For sealing semiconductor devices, novolak resins such as phenol novolak and cresol novolak are preferably used from the viewpoint of heat resistance, moisture resistance and storage stability, and two or more curing agents may be used in combination depending on the application.

In the present invention, the epoxy resin (A) and the curing agent (B)
Is preferably 0.5 to 1.6, more preferably 0.8 to 1.3, from the viewpoint of mechanical properties and moisture resistance.

In the present invention, a curing catalyst may be used to accelerate the curing reaction between the epoxy resin (A) and the curing agent (B). The curing catalyst is not particularly limited as long as it promotes the curing reaction. For example, 2-methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methyl Imidazole compounds such as imidazole and 2-heptadecyl imidazole, triethylamine, benzyldimethylamine, α-methylbenzyldimethylamine,
Tertiary amine compounds such as-(dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, 1,8-diazabicyclo (5,4,0) undecene-7, zirconium tetramethoxide, zirconium Tetrapropoxide, tetrakis (acetylacetonato)
Organometallic compounds such as zirconium and tri (acetylacetonato) aluminum and organic phosphine compounds such as triphenylphosphine, trimethylphosphine, triethylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine and tri (nonylphenyl) phosphine (F ). Among them, the organic phosphine compound (F) is preferable from the viewpoint of moisture resistance, and triphenylphosphine is particularly preferably used.

Two or more of these curing catalysts may be used in combination depending on the application, and the addition amount thereof is preferably in the range of 0.1 to 10 parts by weight based on 100 parts by weight of the epoxy resin (A).

As the filler (C) in the present invention, fused silica,
Examples include crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia, clay, talc, calcium silicate, titanium oxide, asbestos, and glass fibers. Among them, fused silica is preferably used because it has a large effect of lowering the linear expansion coefficient and is effective in reducing stress. Further, the ratio of the filler (C) is 75 to 90% by weight of the whole, and the filler contains 40% by weight or more of the ground fused silica (C ′) having an average particle size of 10 μm or less in the total silica.
It is preferable from the viewpoint of solder heat resistance.

Here, the average particle diameter means a particle diameter (median diameter) at which the cumulative weight becomes 50%.

The silane coupling agent (D) in the present invention is a polyfunctional silane coupling agent. Specific examples of the polyfunctional silane coupling agent (D) include those represented by the following formula (III).

(R ¹ is a divalent hydrocarbon group having 1 to 20 carbon atoms, R ² is a hydrogen atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms, n is an integer of 1 to 3, and X is 2 An aminoethyl group, a glycidyl group, a methacryl group or a hydride group, Y is an allyl group,
It represents a trimethoxysilylpropyl group, a dimethoxymethylpropyl group, or a glycidyl group. As specific examples of the polyfunctional silane coupling agent (D) in the present invention, 3- [N-allyl-N (2-aminoethyl)] aminopropyltrimethoxysilane, N, N-bis [3- (tri Methoxysilyl) propyl] methacrylamide, 3- (N-allyl-N-glycidyl) aminopropyltrimethoxysilane, 3- (N, N-diglycidyl) aminopropyltrimethoxysilane, 3- [N-allyl-N-glycidyl ) Aminopropyltrimethoxysilane and 3- (N-allyl-N-methacryl) aminopropyltrimethoxysilane.

The amount of the polyfunctional silane coupling agent (D) to be added is generally 0.1 to 5 parts by weight, preferably 0.2 to 3 parts by weight, particularly preferably 0.3 to 1.5 parts by weight, per 100 parts by weight of the filler. Further, depending on the application, other silane coupling agents such as monofunctional epoxy silane, mercapto silane, amino silane, vinyl silane and the like can be used in combination.

In the present invention, it is preferable from the viewpoint of reliability that the filler (C) is subjected to a surface treatment in advance with the polyfunctional silane coupling agent (D).

The resin composition for semiconductor encapsulation of the present invention includes a halogen compound such as a halogenated oxy resin, a flame retardant such as a phosphorus compound, a flame retardant auxiliary such as antimony trioxide, a colorant such as carbon black and iron oxide, and a silicone. Rubber, silicone oil, styrene block copolymer, olefin copolymer, modified nitrile rubber, modified polybutadiene rubber and other elastomers, polyethylene and other thermoplastic resins,
Coupling agents such as titanate coupling agents, long chain fatty acids, metal salts of long chain fatty acids, esters of long chain fatty acids,
Release agents such as amides of long-chain fatty acids and paraffin wax and crosslinking agents such as organic peroxides can be optionally added.

The epoxy resin composition of the present invention is preferably produced by melt-kneading, for example, melt-kneading using a known kneading method such as a Banbury mixer, a kneader, a roll, a single or twin screw extruder and a co-kneader. Is manufactured.

<Example> Hereinafter, the present invention will be specifically described with reference to examples.

Reagents were dry-blended by the mixer in the composition ratios shown in Table 4 with the various silane coupling agents shown in Table 2 and the various fused silicas shown in Table 3 with respect to the formulation shown in Table 1. This was heated and kneaded for 5 minutes using a mixing roll having a roll surface temperature of 90 ° C., and then cooled and pulverized to produce an epoxy-containing composition.

Using this composition, low-pressure transfer molding
Post-curing was performed at 175 ° C for 4 minutes for 5 hours. After the post cure, the physical properties of each composition were measured by the following physical property measuring methods.

Solder heat resistance: Twenty-four 80-pin QFPs were humidified at 85 ° C./85% RH for 50 hours, immersed in a solder bath heated to 260 ° C. for 10 seconds, and the ratio of the number of QFPs without cracks was determined.

Reliability: 120 ° C / 85% RH, bias voltage 15 using 44pin QFP
USPCBT was performed on V, and the time until the cumulative failure rate became 50% was calculated.

The moldability was evaluated by the following method using the epoxy resin composition produced by the above method.

Var: Resin flash was measured using a flash mold by a low pressure transfer molding method.

Hot hardness: 175 ℃ × 2 by low pressure transfer molding
The molding was performed under the conditions of minutes, and the hardness when heated (Shore D) was measured.

 Table 4 summarizes the above evaluation results.

As can be seen from Table 4, the compositions using the polyfunctional silane coupling agent of the present invention (Examples 1 to 3) are excellent in balance of solder heat resistance, reliability, burr and hot hardness.

On the other hand, the compositions (Comparative Examples 1 to 4) using no polyfunctional silane coupling agent of the present invention are inferior in solder heat resistance, reliability, burrs and hot hardness.

Further, the epoxy resin composition of the present invention containing a specific epoxy resin in an amount of 30% by weight or more (Examples 4 and 5) has excellent moldability such as reliability, burr, and heat hardness, and also has solder heat resistance. It is even better.

Furthermore, the epoxy resin composition of the present invention containing specific fused silica (Examples 6 to 9) has further improved solder heat resistance.

<Effects of the Invention> The epoxy resin composition of the present invention is excellent in solder heat resistance, reliability, and moldability because it contains a polyfunctional silane coupling agent, a curing agent, a filler, and an epoxy resin. It has ideal performance as a stop.

 ────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-3-285943 (JP, A) JP-A-3-192151 (JP, A) JP-A-3-192150 (JP, A) JP-A-3-192150 134016 (JP, A) JP-A-3-134014 (JP, A)

Claims (2)

(57) [Claims] 1. An epoxy resin (A) containing 30% by weight or more of an epoxy resin (a) having a skeleton represented by the following formula (I), a curing agent (B), a filler (C), and a polyfunctional silane. An epoxy resin composition for semiconductor encapsulation containing a coupling agent (D). (However, R1 to R8 are hydrogen atoms, C1 to C4 lower alkyl groups or halogen atoms) 2. A semiconductor device in which a semiconductor element is sealed with the epoxy resin composition for semiconductor sealing according to claim 1.