JPH0782343A - Epoxy resin composition for sealing semiconductor and semiconductor device sealed therewith - Google Patents

Abstract

PURPOSE:To provide an epoxy resin composition for reading a semiconductor excellent in flame retardancy and high-temperature reliability by mixing a specified epoxy resin with a curing agent, a filler and a specified flame retardant in a specified ratio and to provide a semiconductor device sealed with the resin composition. CONSTITUTION:The resin composition is prepared by mixing an epoxy resin mixture essentially consisting of an epoxy resin having a skeleton represented by the formula (wherein R<1> to R<8> are each H, halogen or 1-4C alkyl) with a curing agent (B), a filler (C), a bromine compound (D) and an antimony compound (E), wherein the rate of component C is 87-95wt.%, the rate of component D is 0-0.3wt.% based on the entire composition, the oxygen index of the prepared composition is 42% or above. The amount of component A used is usually 2-7wt.%, and the essential component constitutes at least 70% of component A. The amount of component B added is usually 2-7wt.%, and the chemical equivalent ratio of component A to component B is desirably in the range of 0.5-1.5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for semiconductor encapsulation which is excellent in solder heat resistance, flame retardancy and high temperature reliability, and a semiconductor device encapsulated by this resin composition.

[0002]

2. Description of the Related Art Epoxy resins are excellent in heat resistance, moisture resistance, electrical characteristics, adhesiveness, etc., and can be given various characteristics by blending formulation, so they are used as industrial materials such as paints, adhesives and electrical insulation materials. Has been done. For example, as a method for sealing electronic circuit parts such as semiconductor devices, hermetic sealing using metal or ceramics and resin sealing using phenol resin, silicone resin, epoxy resin, etc. have been proposed. However, resin sealing with an epoxy resin is mainly used from the viewpoint of the balance of economy, productivity and physical properties.

In recent years, the mounting of semiconductor devices on a printed circuit board has also been promoted with higher density and automation. Instead of the conventional "insertion mounting method" in which lead pins are inserted into holes in the board, parts are soldered on the surface of the board. Attached “Surface mount method”
Is becoming popular. Along with this, the package (form) is shifting from the conventional DIP (dual in-line package) to a thin FPP (flat plastic package) suitable for high-density mounting and surface mounting.

With the shift to the surface mounting method, the soldering process of a semiconductor device, which has not been a problem so far, has become a serious problem. In the conventional pin insertion mounting method, the lead portion is only partially heated in the soldering process, but in the surface mounting method, the entire semiconductor device is immersed in a heating medium and heated. As a soldering method in the surface mounting method, immersion in a solder bath, heating with a saturated vapor of an inert gas (vapor phase method), an infrared reflow method, or the like is used. In either method, the entire semiconductor device is 210 to 270.
It will be heated to a high temperature of ℃. Therefore, the conventional semiconductor device sealed with the sealing resin has a problem that the reliability is lowered due to cracking in the resin portion during soldering or peeling at the interface between the semiconductor element and the resin. .

The occurrence of cracks in the semiconductor device during the mounting process is said to be due to the moisture absorbed between the post-curing and the mounting process explosively turning into steam and expanding during soldering heating. As a countermeasure, a method is used in which the post-cured semiconductor device is stored in a completely dried and sealed container and shipped. On the other hand, in order to ensure safety, electronic parts such as ICs are obliged to have flame retardancy according to the UL standard. Therefore, a flame retardant such as a bromine compound and antimony trioxide is usually added to the sealing resin.

However, flame retardants such as bromine compounds and antimony compounds, which have been added for the purpose of imparting flame retardancy, are not reliable when the semiconductor is used in a high temperature environment of 150 to 200 ° C., that is, high temperature reliability. Cause a decrease in sex. Various improvements have been made to the sealing resin. For example, a method of blending a novolac type epoxy resin and a phenol aralkyl resin in a matrix resin for the purpose of improving solder heat resistance (JP-A-53-299 and JP-A-5).
No. 9-67660), a method in which a biphenyl type epoxy resin and a phenol aralkyl resin are used as a matrix resin and a filler is mixed in an amount of 60 to 85% by weight (Japanese Patent Laid-Open No. 3-20).
7714, JP-A-4-48759, JP-A-4-55423) and the like have been proposed.

Further, in order to improve the moisture resistance and heat resistance of the encapsulating resin, a hydrotalcite compound (JP-A-61-1)
9625), addition of antimony tetroxide (Japanese Patent Publication No. 5)
7-32506 and JP-A-2-175747) have been proposed.

[0008]

However, the method of enclosing the dry package in the container has the drawbacks that the manufacturing process and the handling of the product are complicated, and the product price is high. Also, resins improved by various methods have been effective, but they are not yet sufficient. A method of blending a matrix resin with a novolac type epoxy resin and a phenol aralkyl resin (JP-A-53-299 and JP-A-59-67660), and a crushing system using a biphenyl epoxy resin and a phenol aralkyl resin as the matrix resin. A method of blending 60 to 85% by weight of a filler (JP-A-3-207714, JP-A-4-487).
In Japanese Patent Laid-Open No. 59 and Japanese Patent Laid-Open No. 4-55423), not only the melt viscosity of the matrix resin is high and there is a problem in the filling property, but also cracking of the resin portion in the soldering process is not sufficient.

High-temperature reliability guarantees the function of a semiconductor in a high-temperature environment of 150 to 200 ° C., and is an essential performance for a semiconductor having a large heat generation amount, a semiconductor used around the engine of an automobile, etc. It is known that flame-retardant decomposition of bromine compounds and antimony compounds, which are added in order to impart the above, is reduced mainly due to the decomposition. Therefore, an epoxy resin composition for semiconductor encapsulation excellent in both flame retardancy and high-temperature reliability and a semiconductor device encapsulated with this resin composition have not been obtained.

On the other hand, a method of adding a hydro compound in order to improve the moisture resistance of the sealing resin (Japanese Patent Laid-Open No. 61-19 / 1986).
No. 625) is effective in improving high temperature reliability,
It was not enough, and further improvement was desired. In addition, a method of adding antimony tetroxide in order to improve the moisture resistance and heat resistance of the sealing resin (Japanese Patent Publication No. 57-32506).
Japanese Patent Laid-Open No. 2-175747) was not effective in improving high temperature reliability.

An object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation which is excellent in both flame retardancy and high temperature reliability, and a semiconductor device encapsulated with this epoxy resin composition.

[0012]

The present inventors have used an epoxy resin having a biphenyl skeleton as a matrix resin and added 87 to 95% by weight of a filler.
It has been found that the above-mentioned problems can be achieved and an epoxy resin composition for semiconductor encapsulation that meets the purpose can be obtained by adjusting the addition amount of each of the bromine compound and the antimony compound to 0.3% by weight or less, and to the present invention. Reached

That is, the semiconductor encapsulating epoxy resin composition of the present invention is a resin composition comprising an epoxy resin (A), a curing agent (B), a filler (C), a bromine compound (D) and an antimony compound (E). Wherein the epoxy resin (A) has the following general formula (I)

[0014]

[Chemical 3] (Wherein R ^{1 to} R ⁸ represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms) as an essential component, and contain an epoxy resin (a) having a skeleton represented by The proportion of the filler (C) is 87 to 95% by weight of the whole,
The proportion of the bromine compound (D) is 0 to 0.3% by weight of the whole, and the proportion of the antimony compound (E) is 0 to the whole.
It is 0.3% by weight, and the oxygen index of the further adjusted composition is 42% or more.

Further, the present invention is characterized by a semiconductor device in which a part or all of a semiconductor element is sealed with this epoxy resin composition. Hereinafter, the configuration of the present invention will be described in detail. It is important that the epoxy resin (A) constituting the epoxy resin composition for semiconductor encapsulation of the present invention contains the epoxy resin (a) having a skeleton represented by the above formula (I) as an essential component. When the epoxy resin (a) is not contained, not only the effect of preventing the occurrence of cracks in the soldering step is not exhibited, but also sufficient fluidity and flame retardancy cannot be obtained.

In the above formula (I), preferred examples of R ^{1 to} R ⁸ are hydrogen atom, methyl group, ethyl group,
Propyl group, i-propyl group, n-propyl group, sec
-Butyl group, tert-butyl group, chlorine atom, bromine atom and the like. Preferred specific examples of the epoxy resin (a ₁ ) in the present invention include 4,4′-bis (2,3-epoxypropoxy) biphenyl and 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'-tetramethyl-2-bromobiphenyl, 4,4 '
-Bis (2,3-epoxypropoxy) -3,3 ',
5,5'-tetraethylbiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'
-Tetrabutylbiphenyl and the like, 4,4'-
Bis (2,3-epoxypropoxy) piphenyl, 4,
4'-bis (2,3-epoxypropoxy) -3,
3 ', 5,5'-Tetramethylbiphenyl is particularly preferred.

The epoxy resin (A) in the present invention may contain an epoxy resin other than the epoxy (a) in combination with the above epoxy resin (a). Other epoxy resins that can be used in combination include, for example,
Cresol novolac type epoxy resin, phenol novolac type epoxy resin, various novolac type epoxy resins synthesized from bisphenol A and resorcin, bisphenol A type epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic epoxy Examples include resins.

From the viewpoint of fluidity, the ratio of the epoxy resin (a) contained in the epoxy resin (A) is 70% by weight or more, preferably 90% by weight, of the epoxy resin (a) in the epoxy resin (A). It is necessary to contain at least%. In the present invention, the compounding amount of the epoxy resin (A) is usually 2 to 7% by weight, preferably 2 to 5% by weight. When the compounding amount of the epoxy resin (A) is less than 2% by weight, moldability and adhesiveness are insufficient, which is not preferable.

The curing agent (B) in the present invention is not particularly limited as long as it reacts with the epoxy resin (A) and is cured, and specific examples thereof include, for example, phenol novolac resin, cresol novolac resin, and the following. Phenolic compound represented by general formula (II)

[0020]

[Chemical 4] (However, R represents an alkyl group having 1 to 4 carbon atoms, and n represents an integer of 0 or more.) Various novolac resins synthesized from bisphenol A or resorcin, tris (hydroxyphenyl) methane, dihydroxybiphenyl, etc. Examples thereof include phenol compounds, acid anhydrides such as maleic anhydride, phthalic anhydride and pyromellitic anhydride, and aromatic amines such as metaphenylenediamine, diaminodiphenylmethane and diaminodiphenylsulfone. For semiconductor encapsulation, a phenol-based curing agent is preferably used from the viewpoints of heat resistance, moisture resistance and storability, and two or more curing agents may be used in combination depending on the application.

In the present invention, the compounding amount of the curing agent (B) is usually 2 to 7% by weight, preferably 2 to 5% by weight. Further, the compounding ratio of the epoxy resin (A) and the curing agent (B) is such that the chemical equivalent ratio of (B) to (A) is 0.5 to 1.5, especially from the viewpoint of mechanical properties and moisture resistance reliability. 0.8 ~
It is preferably in the range of 1.2. Further, 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 accelerates the curing reaction, for example, 2
-Methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, imidazole compounds such as 2-heptadecylimidazole, triethylamine, benzyldimethylamine,
Tertiary amines such as α-methylbenzyldimethylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, 1,8-diazabicyclo (5,4,0) undecene-7 Compounds, organometallic compounds such as zirconium tetramethoxide, zirconium tetrapropoxide, tetrakis (acetylacetonato) zirconium, tri (acetylacetonato) aluminum, and triphenylphosphine,
Examples thereof include organic phosphine compounds such as trimethylphosphine, triethylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine and tri (nonylphenyl) phosphine. Above all, from the viewpoint of moisture resistance,
Organic phosphine compounds are preferable, and triphenylphosphine is particularly preferable. These curing catalysts are
Two or more kinds may be used in combination depending on the use, and the addition amount is 0.1 to 1 with respect to 100 parts by weight of the epoxy resin (A).
A range of 0 parts by weight is preferred.

As the filler (C) in the present invention, fused silica, crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia, clay, talc, calcium silicate, titanium oxide, antimony oxide, asbestos, glass fiber, etc. 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.

The fused silica referred to herein means an amorphous silica having a true specific gravity of 2.3 or less. The production does not necessarily have to go through the molten state, and any production method can be used. For example, a method of melting crystalline silica, a method of synthesizing from various raw materials, and the like can be mentioned. The shape and particle size of the fused silica are not particularly limited, but fused silica (c: 99-50% by weight of spherical fused silica having an average particle size of 5 μm or more and 30 μm or less and 1-50% by weight of spherical fused silica having an average particle size of 1 μm or less (c 40% by weight or more, preferably 60% by weight or more, more preferably 90% by weight in the filler (C).
From the viewpoint of fluidity, it is preferable that the content is at least wt%.

The average particle size as used herein means a cumulative weight of 50%.
Means the particle size (median diameter). In the present invention, the proportion of the filler (C) is 87 to 95% by weight, preferably 88 to 95% by weight, based on the moldability and low stress. In the present invention, it is preferable in terms of reliability that the filler is surface-treated in advance with a coupling agent such as a silane coupling agent or a titanate coupling agent. As the coupling agent, silane coupling agents such as epoxysilane, aminosilane, mercaptosilane and the like are preferably used.

The bromine compound (D) in the present invention is usually added to the epoxy resin composition for semiconductor encapsulation as a flame retardant and is not particularly limited, and known compounds can be used. Preferred specific examples of the brominated compound (D) include brominated bisphenol A type epoxy resin, brominated epoxy resin such as brominated phenol novolac type epoxy resin, brominated polycarbonate resin, brominated polystyrene resin, brominated polyphenylene oxide resin, Tetrabromobisphenol A, decabromodiphenyl ether and the like can be mentioned. Among them, brominated epoxy resins such as brominated bisphenol A type epoxy resin and brominated phenol novolac type epoxy resin are
It is particularly preferably used from the viewpoint of moldability.

The amount of the bromine compound (D) added is preferably 0 to 0.15% by weight in terms of bromine atoms in terms of flame retardancy and high temperature reliability. Particularly preferably, it is 0 to 0.05% by weight. The antimony compound (E) in the present invention is
It is generally added as a flame retardant aid to the epoxy resin composition for semiconductor encapsulation, and is not particularly limited, and known ones can be used.

Preferred specific examples of the antimony compound (E) include antimony trioxide, antimony tetroxide and antimony pentoxide. The addition amount of the antimony compound (E) is preferably 0 to 0.3% by weight based on the total amount in view of flame retardancy and high temperature reliability. Particularly preferably, it is 0 to 0.1% by weight. The epoxy resin composition of the present invention includes carbon black, a coloring agent such as iron oxide, an ion trapping agent such as hydrotalcite, a silicone rubber, an olefin copolymer, a modified nitrile rubber, a modified polybutadiene rubber, and a modified silicone oil. Elastomers, thermoplastic resins such as polyethylene, long-chain fatty acids, metal salts of long-chain fatty acids, esters of long-chain fatty acids, amides of long-chain fatty acids, release agents such as paraffin wax, and cross-linking agents such as organic peroxides. It can be added arbitrarily.

The epoxy resin composition of the present invention is preferably melt-kneaded, for example, by melt-kneading using a known kneading method such as a Banbury mixer, a kneader, a roll, a single-screw or twin-screw extruder and a cokneader. Manufactured. Next, a semiconductor device encapsulated with the above-mentioned epoxy resin composition for encapsulating a semiconductor element will be described in detail.

FIG. 1 shows an example of a semiconductor device encapsulated with the epoxy resin composition for semiconductor encapsulation of the present invention.
The semiconductor element 1 is bonded to the die pad 3 in the lead frame 2 with a die bond material 4. The lead frame 2 is composed of an inner lead 5 formed around the die pad 3 and an outer lead 6 formed on an extension of the inner lead 5. Further, the electrode pad 7 formed on the semiconductor element 1 joined to the lead frame 2 and the tip of the inner lead 5 corresponding to the electrode pad 7 are electrically joined by a gold wire 8. ing.

The lead frame 2 on which the semiconductor element 1 has been assembled in advance is molded into a mold M as shown in FIG.
Then, the epoxy resin composition K for semiconductor element encapsulation described above is press-molded into the cavity 12 with a flanger P while transfer molding is performed. The epoxy resin composition K for semiconductor element encapsulation is 50 MPa in the molding die M heated to 130 ° C. to 200 ° C. by the plunger P.
It is pressed at the following low pressure. By this press-fitting, the epoxy resin composition K is filled in the cavity 12 forming the semiconductor device in the closest state via the resin introducing runner 10 and the gate 11 formed in the mold M, and then cured. After the curing and releasing, the semiconductor element 1, the die pad 3, the inner lead 2, the gold wire 8 and the like are sealed.
A semiconductor device 20 as shown in is obtained.

As shown in FIG. 3, in the semiconductor device 20 of the present invention, at least the surface portion of the semiconductor element 1, the gold wire 8 and the bonding portion at the tip of the inner lead 5 are made of the epoxy resin composition K for sealing the semiconductor element. It is formed by transfer molding.

[0032]

EXAMPLES The present invention will be specifically described below with reference to examples. In addition,% in an Example shows weight%. Examples 1 to 6 and Comparative Examples 1 to 4 The components shown in Table 1 were dry-blended with a mixer in the composition ratios shown in Table 2. Roll surface temperature 90
The mixture was heated and kneaded for 5 minutes using a mixing roll at ℃, cooled and pulverized to produce an epoxy resin composition for semiconductor encapsulation.

This composition was molded by a low pressure transfer molding method under conditions of 175 ° C. × 2 minutes and 180 ° C. ×
Post cure was carried out under the condition of 5 hours, and the physical properties of the respective compositions were measured by the following physical property measuring methods. Solder heat resistance: 160 pin OFP 20 with a chip size of 12 × 12 mm, mounted with a simulated element with Al vapor deposition on the surface
Each piece was molded, humidified at 85 ° C./85% RH for a predetermined time, and then heat-treated in an IR reflow furnace having a maximum temperature of 245 ° C., and the number of external cracks and internal cracks was examined.

Water absorption rate: 160 pi used for solder heat resistance test
The water absorption rate in nQFP was measured. High temperature reliability: High temperature reliability was evaluated at 200 ° C using a 16pin DIP equipped with a simulation element, and cumulative failure rate was 63%.
Was calculated as the high temperature characteristic life. Flame retardance test: A 5 ″ × 1/2 ″ × 1/16 ″ combustion test piece was molded and post-cured, and flame retardancy was evaluated according to UL94 standard.

Oxygen index: A test piece of 6.5 × 3.2 × 120 mm was molded and post-cured to JIS K7201.
According to the above, each gas volume concentration at the combustion limit point was obtained. Oxygen index (%) = [oxygen] / ([oxygen] + [nitrogen]) PKG filling property: 160pinQF used for solder heat resistance test
After molding, P was observed visually and using a microscope to check whether or not it was unfilled and had pinholes.

[0036]

[Table 1]

[0037]

[Table 2] As seen in Table 2, the epoxy resin compositions of the present invention (Examples 1 to 6) are excellent in solder heat resistance, flame retardancy, high temperature reliability and PKG filling property. On the other hand, if the amount of the filler (C) added is less than 87% by weight, the oxygen index is 42%.
Comparative Example 1, which is less than 1, is inferior in solder heat resistance, flame retardancy, and filling property.

Further, Comparative Example 2 in which the proportions of the bromine compound (D) and the antimony compound (E) are each 0.3% by weight or more of the present invention is inferior in high temperature reliability. In Comparative Example 3 in which the epoxy resin (a) of the present invention is not used, the composition has a low oxygen index, and thus not only sufficient flame retardancy cannot be obtained, but also the solder heat resistance is poor.

[0039]

The epoxy resin composition for semiconductor encapsulation of the present invention uses an epoxy resin having a biphenyl skeleton as an epoxy resin, and in addition to adding 87 to 95% by weight of a filler, a bromine compound or an antimony compound. Since the addition amount of is less than 0.3% by weight, not only the solder heat resistance is excellent, but also the oxygen index is as high as 42% or more, and the flame retardancy and high temperature reliability are excellent.

Since the semiconductor device of the present invention is encapsulated with the above epoxy resin composition for semiconductor encapsulation, it is excellent in solder heat resistance as well as in flame retardancy and high temperature reliability. Will be things.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional view showing an example of an assembly of a semiconductor element and a lead frame used in a semiconductor device of the present invention.

FIG. 2 is an explanatory view showing a situation in which the assembly of FIG. 1 is transfer-molded with the epoxy resin composition for semiconductor encapsulation of the present invention by molding.

FIG. 3 is a vertical cross-sectional view of the semiconductor device of the present invention obtained by the process of FIG.

[Explanation of symbols]

1 Semiconductor Element 2 Lead Frame 3 Die Pad 5 Inner Lead 6 Outer Lead 7 Electrode Pad 8 Gold Wire K Epoxy Resin Composition for Semiconductor Encapsulation

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location H01L 23/31 (72) Inventor Masayuki Tanaka 1 Toray of 9 Oe-cho, Minato-ku, Nagoya, Aichi Prefecture Inside the Nagoya Plant (72) Inventor Toshimi Kawahara 1015 Kamiodanaka, Nakahara-ku, Kawasaki City Fujitsu Limited Kawasaki Plant

Claims (2)

[Claims] 1. A resin composition comprising an epoxy resin (A), a curing agent (B), a filler (C), a bromine compound (D) and an antimony compound (E), wherein the epoxy resin (A) is The following general formula (I): (Wherein R ^{1 to} R ⁸ represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms) as an essential component, and contain an epoxy resin (a) having a skeleton represented by The proportion of the filler (C) is 87 to 95% by weight of the whole,
The proportion of the bromine compound (D) is 0 to 0.3% by weight of the whole, and the proportion of the antimony compound (E) is 0 to the whole.
An epoxy resin composition for semiconductor encapsulation, characterized in that the composition has an oxygen index of 0.3% by weight and the oxygen index of the adjusted composition is 42% or more. 2. A semiconductor element is partially or entirely sealed with an epoxy resin composition, and the epoxy resin composition comprises an epoxy resin (A), a curing agent (B), a filler (C), and a bromine compound ( D), antimony compound (E)
The epoxy resin (A) is represented by the following general formula (I): (Wherein R ^{1 to} R ⁸ represent a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms) as an essential component, and contain an epoxy resin (a) having a skeleton represented by The proportion of the filler (C) is 87 to 95% by weight of the whole,
The proportion of the bromine compound (D) is 0 to 0.3% by weight of the whole, and the proportion of the antimony compound (E) is 0 to the whole.
A semiconductor device characterized in that the oxygen index of the composition is 0.3% by weight and the adjusted composition has an oxygen index of 42% or more.