JPH11181238A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having excellent moldability, soldering resistance and electric characteristics at high temperatures by compounding stilbene type epoxy resins, an epoxy resin, a phenolic resin-curing agent, an inorganic filler, a curing-accelerating agent, a brominated epoxy resin and antimony tetraoxide. SOLUTION: This epoxy resin composition comprises (A) epoxy resins containing the mixture of a stilbene type epoxy resin of formula I (R1 -R4 are each H, a 1-6C alkyl or a halogen; aryl groups bound to the C=C bond are the same as each other) with a stilbene type epoxy resin of formula II (R5 -R12 are each H, a 1-6C alkyl or a halogen; aryl groups bound to the C=C bond are different from each other) in an amount of >=30 wt.% based on the total amount of the epoxy resins, (B) a phenolic resin-curing agent (for example, a phenolic novolak), (C) an inorganic filler (for example, alumina), (D) a curing- accelerating agent (for example, triphenylphosphine), (E) a brominated epoxy resin and (F) antimony tetraoxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to moldability, solder resistance,
The present invention relates to an epoxy resin composition for semiconductor encapsulation having excellent electrical properties at high temperatures, and a semiconductor device using the same.

[0002]

2. Description of the Related Art In order to reduce the size, weight, and performance of electronic products, semiconductors have become more highly integrated, and semiconductor packages have taken various forms. Particularly, in recent years, due to surface mounting, there has been a problem that cannot be solved by a conventional epoxy resin composition for semiconductor encapsulation (hereinafter referred to as a resin composition), and various studies have been made. The biggest problem is that the adoption of the surface mounting of the semiconductor package causes the package to be dipped in solder or suddenly in the reflow process.
Exposure to high temperatures of over ℃ causes cracks in packages, various types of plated joints on chips, lead frames, inner leads, or LOC (Lead on).
In a package having a Chip) structure, peeling occurs at each interface between a polyimide tape adhesive or the like and a cured product of the resin composition, and this is a phenomenon in which reliability is significantly reduced. Further, in recent years, the thickness of the resin composition occupying in the package has been further reduced as the package becomes thinner. These thin packages are required to have good package filling properties at the time of molding the resin composition, to have little gold wire deformation, and to have no chip or lead frame deformation (referred to as chip shift or die pad shift). The composition needs to have excellent fluidity during molding.

[0003] In order to achieve both a reduction in reliability due to soldering and an improvement in fluidity during molding, high filling of an inorganic filler in a resin composition achieves low moisture absorption, high strength, and low thermal expansion. In addition, a method of improving solder resistance and using a resin having a low melt viscosity to maintain a low viscosity at the time of molding and a high fluidity is becoming common. As the epoxy resin used in this method, there is a crystalline epoxy resin which is solid at normal temperature and extremely lowers in viscosity when melted, and as a typical example, a biphenyl type epoxy resin has begun to be widely used (in particular, JP-A-5-175364,
JP-A-5-343570, JP-A-6-80763
No.).

[0004] However, conventional crystalline epoxy resins, particularly biphenyl type epoxy resins, are characterized by low melt viscosity at the molding temperature, but the biphenyl structure, which is the main skeleton thereof, has a limit of the number of functional groups of only two functions. In addition, it has been pointed out that there is a problem that the properties of the cured product such as the strength at heat and the glass transition temperature are low. In addition, a problem has begun that electrical characteristics deteriorate when a semiconductor package sealed with an epoxy resin composition using a biphenyl type epoxy resin is treated at a high temperature of 150 ° C. or higher for a long time. It has been found that the cause is greatly affected by the low glass transition temperature of the cured product of the resin composition using the biphenyl type epoxy resin, and improvement is desired.

[0005]

SUMMARY OF THE INVENTION The present invention provides an epoxy resin composition for semiconductor encapsulation which is excellent in moldability, solder resistance, and electrical characteristics at high temperatures, and a semiconductor device using the same.

[0006]

That is, the present invention provides (A)
A stilbene type epoxy resin represented by the general formula (1),
An epoxy resin containing a mixture of the stilbene type epoxy resin represented by the general formula (2) in an amount of 30% by weight or more in the total epoxy resin, (B) a phenol resin curing agent, (C) an inorganic filler, (D) a curing accelerator, (E) a brominated epoxy resin,
(F) An epoxy resin composition for semiconductor encapsulation, which is made of diantimony tetroxide, and a semiconductor device, which is encapsulated with an epoxy resin composition.

[0007]

Embedded image (Here, R _{1 to} R ₄ each independently represent a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. The two aryl groups being linked are the same as each other.)

[0008]

Embedded image (Here, R _{5 to} R ₁₂ each independently represent a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. The two aryl groups being linked are different from each other.)

Further, the present invention relates to (A) a mixture of a stilbene type epoxy resin represented by the general formula (1) and a stilbene type epoxy resin represented by the general formula (2) in an amount of 30% by weight or more in the total epoxy resin. Epoxy resin, (B) phenolic resin curing agent, (C) inorganic filler, (D) curing accelerator, (E) brominated epoxy resin, (F) diantimony tetroxide, (G) bismuth oxide hydrate And an epoxy resin composition for encapsulating a semiconductor, comprising at least one inorganic ion exchanger selected from the group consisting of: and a hydrotalcite compound; and a semiconductor, which is encapsulated by an epoxy resin composition. Device.

[0010]

Embedded image (Here, R _{1 to} R ₄ each independently represent a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. The two aryl groups being linked are the same as each other.)

[0011]

Embedded image (Here, R _{5 to} R ₁₂ each independently represent a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. The two aryl groups being linked are different from each other.)

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The epoxy resin in the component (A) used in the present invention is a mixture of a stilbene type epoxy resin represented by the general formula (1) and a stilbene type epoxy resin represented by the general formula (2). Many studies have been made on stilbene-structured epoxy resins, and many reports have been published.
Some applications to semiconductor sealing materials have also been proposed (JP-A-6-345849, JP-A-8-735).
No. 62, etc.). Since this stilbene skeleton has a rigid planar or rod-like structure, the molecules are easily aligned with each other, and thus is a typical structure of liquid crystal or liquid crystalline polymer. After curing, the resin composition using the epoxy resin having this structure exhibits good heat resistance due to the rigid molecular skeleton of the epoxy resin and the orientation of the molecules. For this reason, it has features such as a higher glass transition temperature and a higher strength at the time of heat, and superior moisture resistance, as compared with a biphenyl type epoxy resin which is a typical crystalline epoxy resin. Further, since the glass transition temperature is higher than that of the biphenyl type epoxy resin, the deterioration of the electrical characteristics of the semiconductor sealed with the epoxy resin composition using the same in a high temperature atmosphere is higher than in the case where the biphenyl type epoxy resin is used. There are few features.

Further, since the epoxy resin having this structure is easily oriented in molecules due to shear stress, the resin in the mold in low pressure transfer molding (particularly in a mold having a structure easily subjected to shear stress like a thin package) is used. The fluidity of the composition is high, and the filling property into a thin package is excellent. Therefore, it is an epoxy resin suitable for the resin composition for thin package sealing which is the object of the present invention. The substituents R _{1 to} R ₁₂ of the stilbene-type epoxy resin represented by the general formulas (1) and (2) each represent a hydrogen atom,
6, a group or atom selected from the group consisting of a chain or cyclic alkyl group, and halogen, which may be the same or different, such as a hydrogen atom, a methyl group, an ethyl group, and a propyl group. Butyl group, amyl group, hexyl group (including each isomer), cyclohexyl group, chlorine atom, bromine atom and the like. Particularly, from the low melt viscosity of the epoxy resin, methyl group, ethyl group, propyl group ,
Or a butyl group is preferable. Further, carbon of the general formula (1)
The two aryl groups bonded to the carbon double bond are the same as each other, and the two aryl groups bonded to the carbon-carbon double bond of the general formula (2) are different from each other. This epoxy resin is a mixture of a stilbene-type epoxy resin of the general formula (1) and a stilbene-type epoxy resin of the general formula (2). The stilbene-type epoxy resin of the general formula (1) and the stilbene-type epoxy resin of the general formula (2) The stilbene type epoxy resins have various structures depending on the type of the substituent and the like. By mixing the stilbene-type epoxy resin of the general formula (1) and the stilbene-type epoxy resin of the general formula (2), a eutectic mixture having a melting point lower than each melting point is obtained, and thus the viscosity of the epoxy resin composition is reduced. This is advantageous. There is no particular limitation on the mixing method.For example, stilbene-type phenols, which are raw materials for stilbene-type epoxy resins, are mixed before glycidyl etherification,
There is a method of melting and mixing both stilbene type epoxy resins.

As the stilbene type epoxy resin represented by the general formula (1), 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylstilbene, 4,4′- Dihydroxy-3,3'-ditert-butyl-6,6'-dimethylstilbene, 4,4'-dihydroxy-3,3'-ditert-butyl-5,5 '
Glycidyl etherified dimethylstilbene is particularly preferred. As the stilbene type epoxy resin represented by the general formula (2), 5-tert-butyl-4,4′-dihydroxy-2,3 ′, 5′-trimethylstilbene and 3-tert-butyl are preferred in terms of performance and raw material price. Glycidyl etherified products of -4,4'-dihydroxy-3 ', 5,5'-trimethylstilbene are particularly preferred. General formula (1)
The stilbene type epoxy resin of the formula (2) and the stilbene type epoxy resin of the general formula (2) are used as a mixture, and the ratio is as follows: [Formula (1) / Formula (2) = 20 to 80% by weight / 8
0 to 20% by weight]. Outside this range, the viscosity may increase, which is not preferred.

The epoxy resin usable in combination with the epoxy resin of the present invention includes all monomers, oligomers and polymers having an epoxy group.
Type epoxy resin, orthocresol novolak type epoxy resin, naphthol type epoxy resin, triphenolmethane type epoxy resin, dicyclopentadiene modified phenol type epoxy resin, etc., in order to obtain a resin composition having particularly excellent solder resistance. Shows crystallinity at room temperature represented by biphenol diglycidyl ether type epoxy resin, tetramethyl biphenol diglycidyl ether type epoxy resin, hydroquinone diglycidyl ether type epoxy resin, tetramethyl bisphenol F diglycidyl ether type epoxy resin, etc. Epoxy resins are preferred. The epoxy resins used in combination with the general formulas (1) and (2) may be used alone or as a mixture. The proportion of the total stilbene type epoxy resin used in the present invention is desirably 30% by weight or more in the total epoxy resin. If the content is less than 30% by weight, the high fluidity and high heat resistance at the time of molding, which are characteristics of the crystalline epoxy resin, are not exhibited.

The component (B) phenolic resin curing agent used in the present invention refers to all monomers, oligomers and polymers having a phenolic hydroxyl group capable of forming a crosslinked structure by a curing reaction with an epoxy resin. , Xylylene-modified phenolic resin, terpene-modified phenolic resin, dicyclopentadiene-modified phenolic resin, bisphenol A-type phenolic resin, triphenolmethane-type phenolic resin, and the like,
It is not limited to these. These phenolic resins can be used alone or in combination. The equivalent ratio of the epoxy groups of all epoxy resins used in the present invention to the phenolic hydroxyl groups of all phenolic resins is preferably 0.5 to 2, and particularly preferably 0.7 to 1.5.
If the ratio is out of the range of 0.5 to 2, the curability, moisture resistance and the like are deteriorated, which is not preferable.

The type of the inorganic filler (C) used in the present invention is not particularly limited, and those generally used for a sealing material can be used. For example,
Examples thereof include fused silica obtained by melting natural silica in a flame, crystalline silica, alumina, and synthetic silica obtained by hydrolyzing tetramethoxysilane, tetraethoxysilane, and the like. There are two types of fused silica, spherical silica and crushed silica, depending on the shape and manufacturing method. Either of them may be used. However, when the filler is highly filled, it is preferable to increase the use ratio of the spherical silica. The compounding amount of the inorganic filler (C) used in the present invention is preferably 75 to 93% by weight in the whole resin composition. If the amount is less than 75% by weight, the molded package will have an increased amount of moisture absorption, and the strength at the soldering temperature will be reduced. On the other hand, if it exceeds 93% by weight, the fluidity during molding of the resin composition decreases,
Unfilling, chip shift, and pad shift are likely to occur, which is not preferable.

The curing accelerator of the component (D) used in the present invention may be any as long as it promotes the crosslinking reaction between the epoxy resin and the phenol resin curing agent.
1,8-diazabicyclo (5,4,0) undecene-7
And the like, an organic phosphorus compound such as triphenylphosphine, tetraphenylphosphonium / tetraphenylborate salt, and an imidazole compound such as 2-methylimidazole, but are not limited thereto. These curing accelerators may be used alone or as a mixture.

The brominated epoxy resin of the component (E) used in the present invention refers to all epoxy resins having a bromine atom in the resin skeleton, and these are well-known flame retardants. Bromine atoms in the brominated epoxy resin exhibit a flame retardant action when the cured product of the epoxy resin composition burns.
Specifically, a tetrabromobisphenol A type epoxy resin, a brominated phenol novolak type epoxy resin and the like are particularly preferable.

The stilbene type epoxy resin of the component (A) has a higher glass transition temperature than other crystalline epoxy resins typified by a biphenyl type epoxy resin due to its rigid structure. As described above, the reliability of the electrical characteristics below is improved. However, since this epoxy resin is also bifunctional, its glass transition temperature is lower than that of a polyfunctional epoxy resin represented by, for example, a cresol novolak type epoxy resin, and the reliability of electric characteristics in a high-temperature atmosphere is reduced. I do. Further, the stilbene type epoxy resin has a non-aromatic carbon-hydrogen atom between benzene rings unlike the biphenyl type epoxy resin, and thus has a disadvantage that it is easily burned. For this reason, unless the flame retardant component is added in a larger amount than the biphenyl type epoxy resin, the flame resistance is not exhibited. However, when the amount of the flame retardant component is increased, bromine atoms derived from the brominated epoxy resin and antimony ions derived from the antimony oxide compound increase. Both of these ions have a correlation that lowers the electrical characteristics of the semiconductor element under a high-temperature atmosphere, and it is necessary to reduce these ions as much as possible.

The diantimony tetroxide (F) used in the present invention is used for imparting flame retardancy to the epoxy resin composition. Generally, diantimony trioxide, diantimony tetroxide, diantimony pentoxide, and the like are known for imparting flame retardancy. Of these, diantimony tetroxide has high thermal stability and can be used even in a high-temperature atmosphere. Since the amount of generated antimony ions is small, a decrease in electrical characteristics of the semiconductor device is small and reliability is improved.

The inorganic ion exchanger (G) used in the present invention is selected from at least one of bismuth oxide hydrate and hydrotalcite compounds. Specific examples of bismuth oxide hydrate include the following, but are not limited thereto. "Bismuth oxide hydrate" · BiOx (OH) y ( NO 3) z · nH 2 O, (x = 0.9~1.1, y
= 0.6~0.8, z = 0.2~0.4, n represents a positive number) · SbBiwOx (OH) y ( NO 3) z · nH 2 O, (w = 0.6~0.
9, x = 3.1~3.4, y = 0.4~0.7, z = 0.2~0.4, n represents a positive number) · SbSivBiwOx (OH) y ( NO 3) z · nH 2 O, (v = 0.1
~ 0.3, w = 1.5-1.9, x = 4.1-4.5, y = 1.2-1.6, z =
(0.2 to 0.3, n represents a positive number) << Hydrotalcite compounds >> Mg _x Al _y (OH) _{2x + 3y-2z} (CO ₃ ) _z n H ₂ O (x, y, z
Are 0 <y / x ≦ 1, 0 <z / y ≦ 1.5, respectively.
(n represents a positive number) The above-mentioned inorganic ion exchanger traps bromine ions which are free from the brominated epoxy resin contained in the epoxy resin composition and antimony ions generated from antimony oxide. This has the effect of improving reliability.

The inorganic ion exchanger of the component (G) captures these ions and can prevent a decrease in electric characteristics under a high-temperature atmosphere. Accordingly, the stilbene type epoxy resin as the component (A) can be further improved without impairing the feature of being excellent in electric characteristics under a high temperature atmosphere. That is,
It is possible to achieve both high fluidity at the time of molding an epoxy resin composition using a crystalline epoxy resin and improvement in electrical properties under a high-temperature atmosphere.

[0024] The resin composition of the present invention may comprise a component (A) to component (F) or a component (A) to component (G), if necessary, a low stress agent represented by a polysiloxane compound, and a coupling agent. A coloring agent represented by carbon black, a release agent such as a natural wax and a synthetic wax, and the like can be appropriately compounded. In order to obtain a molding material, after mixing all components, the mixture is heated and kneaded using a heating kneader or a hot roll, and then cooled and pulverized to obtain a desired resin composition. The semiconductor device of the present invention can be obtained by using the above-described epoxy resin composition for semiconductor encapsulation and encapsulating the semiconductor element by transfer molding, compression molding, injection molding or the like.

[0025]

The present invention will be specifically described below with reference to examples. << Example 1 >> 3.2 parts by weight of epoxy resin having a structure of formula (3) as a main component 2.2 parts by weight of epoxy resin having a structure of formula (4) as a main component ・ shown by formula (5) phenolic resin 4.6 parts by weight of bismuth oxide hydrate 0.5 part by weight of [formula _{BiOx (OH) y (NO 3} ) z, manufactured by Toagosei Co., Ltd. IXE-500S] · spherical fused silica powder 85. 0 parts by weight-1,8-diazabicyclo (5,4,0) undecene-7 0.2 parts by weight [hereinafter referred to as DBU]-2.0 parts by weight of diantimony tetroxide [79% antimony atom content]-Carbon black 0.3 parts by weight ・ Brominated bisphenol A type epoxy resin 1.2 parts by weight [bromine content 50%] ・ γ-glycidoxypropyltrimethoxysilane 0.5 parts by weight ・ Carnauba wax 0.3 parts by weight After mixing using a mixer, Surface temperature is 90
The mixture was kneaded 30 times using two rolls at a temperature of 45 ° C. and a temperature of 45 ° C. The obtained kneaded material sheet was cooled and pulverized to obtain a resin composition.
The properties of the obtained resin composition were evaluated by the following methods. Table 1 shows the results.

[0026]

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<< Evaluation Method >> Spiral flow: Using a mold for spiral flow measurement in accordance with EMMI-I-66, mold temperature 175
C., injection pressure was 70 kg / cm ² , and curing time was 2 minutes. A package having a Bacol hardness of 16 pSOP was subjected to transfer molding at a mold temperature of 175 ° C. and a molding pressure of 75 kg / cm ² for 2 minutes. Ten seconds after the mold was opened, the surface hardness of the molded product was measured with a Bacol hardness tester # 935. -Flame resistance: 1.0 mm according to the UL-94 test method
Thickness test pieces were fired. The results are expressed as the UL-94 flame resistance level. -High-temperature reliability: when processed at 185 ° C. using a 16pSOP equipped with a simulated element, the electrical resistance value becomes the initial value of 2
The processing time until the number of packages to be doubled exceeds 50% is shown.

Heat strength: The bending strength at 240 ° C. is determined by JI.
It was measured under the test conditions of S-K6911. Solder resistance: 100-pin TQFP package (package size: 14 × 14 mm, thickness: 1.4 mm, silicon chip size: 8.0 × 8.0 mm, lead frame made of 42 alloy), mold temperature of 175 ° C., 75 kg / Cm
Perform transfer molding for 2 minutes at ² injection pressure, 17
Post-curing was performed at 5 ° C. for 8 hours. 85 molded product packages
It was left for 168 hours in an environment of 85 ° C. and a relative humidity of 85%, and then immersed in a solder bath at 240 ° C. for 10 seconds. The package was observed with a microscope, and external cracks were indicated by [(number of packages in which cracks occurred) / (number of all packages) × 100]%. The ratio of the peeled area between the chip and the cured product of the resin composition was measured using an ultrasonic flaw detector, and the peeling rate was expressed as [(peeled area) / (chip area) × 100]%.

<< Examples 2 to 4, Comparative Examples 1 to 6 >> Example 1
Was replaced with each other in the proportions shown in Tables 1 and 2, and mixed and kneaded in the same manner as in Example 1 to obtain a resin composition. Tables 1 and 2 show the results of the evaluation performed in the same manner as in Example 1.

The epoxy resins and phenolic resins used in other examples or comparative examples are as follows. · Hydrotalcite compound: formula _{Mg x Al y (OH) 2x} + 3y-2z (CO 3) z · nH 2 O [ manufactured by Kyowa Chemical Industry Co., Ltd. DHT-4A] - biphenyl type epoxy resin: wherein ( Epoxy resin having the structure of 6) as a main component [YX manufactured by Yuka Shell Epoxy Co., Ltd.]
-4000H]

[0031]

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[0032]

[Table 1]

[0033]

[Table 2]

[0034]

When the epoxy resin composition of the present invention is used, the obtained semiconductor package is excellent in electrical characteristics in a high-temperature atmosphere, reliability and solder resistance after moisture absorption.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 3/00 C08K 3/00 3/22 3/22 3/26 3/26 H01L 23/29 H01L 23/30 R 23/31

Claims (3)

[Claims] (A) an epoxy resin comprising a mixture of a stilbene type epoxy resin represented by the general formula (1) and a stilbene type epoxy resin represented by the general formula (2) in an amount of 30% by weight or more in a total epoxy resin; An epoxy resin for semiconductor encapsulation comprising (B) a phenolic resin curing agent, (C) an inorganic filler, (D) a curing accelerator, (E) a brominated epoxy resin, and (F) diantimony tetroxide. Composition. Embedded image (Here, R _{1 to} R ₄ each independently represent a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. The two aryl groups bonded are the same as each other.) (Here, R _{5 to} R ₁₂ each independently represent a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. The two aryl groups being linked are different from each other.) (A) an epoxy resin containing a mixture of a stilbene type epoxy resin represented by the general formula (1) and a stilbene type epoxy resin represented by the general formula (2) in an amount of 30% by weight or more in a total epoxy resin; (B) phenolic resin curing agent, (C) inorganic filler, (D) curing accelerator, (E) brominated epoxy resin, (F) diantimony tetroxide, (G)
An epoxy resin composition for semiconductor encapsulation comprising at least one inorganic ion exchanger selected from bismuth oxide hydrate and hydrotalcite compounds. Embedded image (Here, R _{1 to} R ₄ each independently represent a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. The two aryl groups bonded are the same as each other.) (Here, R _{5 to} R ₁₂ each independently represent a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. The two aryl groups being linked are different from each other.) 3. A semiconductor device sealed with the epoxy resin composition according to claim 1.