JP2002053735A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition for sealing a semiconductor, having both excellent soldering crack resistance and excellent reliability in moisture resistance. SOLUTION: The epoxy resin composition comprises essentially (A) an epoxy resin, (B) a phenol resin, (C) a cure accelerator, (D) an inorganic filler, and (E) an ion acceptor coated with an organosilicon compound having at least one alkyl group directly bonded to an Si atom.

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 having excellent moisture resistance reliability and a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, diodes, transistors,
Semiconductor devices such as integrated circuits are mainly sealed using an epoxy resin composition. Particularly, for an integrated circuit, an epoxy resin composition containing an inorganic filler such as an epoxy resin, a phenol resin, a fused silica, and a crystalline silica having excellent heat resistance and moisture resistance is used. However, in recent years, semiconductor elements have become larger due to higher integration of integrated circuits, and semiconductor devices have become smaller and thinner QFPs, SOPs, SOJs, TSOPs, TQFPs, and PLCs that are surface-mounted from conventional DIP types.
C and BGA types are changing. Surface-mounted semiconductor devices tend to cause problems such as cracks in the semiconductor device due to thermal stress during mounting, and separation at the interface between the semiconductor element and other components and the cured product of the epoxy resin composition, and have excellent heat resistance. There is a strong need for an epoxy resin composition. On the other hand, a large number of semiconductor devices have been mounted on outdoor devices such as automobiles, and the reliability required to withstand more severe environments than when used in indoor devices has been required. Therefore, the epoxy resin compositions used in these surface-mount type semiconductor devices include crystalline epoxy resins such as biphenyl type epoxy resins that can obtain more toughness from conventional ortho-cresol novolak type epoxy resins and low moisture absorption. An epoxy resin having a low molecular weight and a small number of functional groups, such as a dicyclopentadiene-modified phenol type epoxy resin, has been used, and has been able to withstand thermal stress during mounting.

However, these epoxy resins have a glass transition temperature of a cured product lower than that of conventional epoxy resins due to their chemical structure. Therefore, at high temperature or high humidity, Cl ⁻ , Br ⁻ , Since ionic impurities such as Na ⁺ easily precipitate and the corrosion of the semiconductor circuit easily progresses, there is a problem in the moisture resistance reliability. In order to capture ionic impurities contained in the epoxy resin composition, which cause poor moisture resistance reliability, hydrotalcite compounds and their baked products, hydroxides and oxides of Bi, Sb, and Zr are used. In many cases, an epoxy resin composition containing an ion-trapping material containing the same is used. Among the calcined products of hydrotalcite compounds, the compound represented by the general formula (1), when trapping anionic impurities, itself It has a structure that absorbs anions inside, has high anion trapping ability compared to hydrotalcite compounds, and the epoxy resin composition containing this is suppressed from being corroded by anionic impurities,
Improvement in moisture resistance reliability is observed. However, although the epoxy resin composition using the compound represented by the general formula (1) has improved moisture resistance reliability, it has a remarkably increased hygroscopicity, and cracks due to thermal stress in a surface mount type semiconductor device, that is, cracks due to thermal stress. In the soldering process, by being rapidly exposed to a high temperature of 200 ° C. or higher, the solder crack resistance such as peeling at the interface between the cured product of the epoxy resin composition and the semiconductor device and deterioration of moisture resistance due to cracks is increased. It was not suitable for practical use due to the problem of lowering.

[0004]

SUMMARY OF THE INVENTION The present invention provides an epoxy resin composition for semiconductor encapsulation which has both excellent solder crack resistance and excellent moisture resistance reliability, and a semiconductor device.

[0005]

The present invention provides (A) an epoxy resin, (B) a phenolic resin, (C) a curing accelerator,
An epoxy for semiconductor encapsulation comprising, as essential components, (D) an inorganic filler, and (E) an ion-trapping material coated with an organosilicon compound having one or more alkyl groups bonded directly to one Si atom. A semiconductor device comprising a resin composition and a semiconductor element sealed with the resin composition.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin used in the present invention refers to all monomers, oligomers and polymers having two or more epoxy groups in one molecule, for example, biphenyl type epoxy resin, stilbene type epoxy resin,
Bisphenol-type epoxy resin, triphenolmethane-type epoxy resin, alkyl-modified triphenolmethane-type epoxy resin, dicyclopentadiene-modified phenol-type epoxy resin, naphthol-type epoxy resin, triazine nucleus-containing epoxy resin, and the like can be used alone or mixed. You may use it.

The phenolic resin used in the present invention includes:
Monomers, oligomers and polymers generally having two or more phenolic hydroxyl groups in one molecule, such as dicyclopentadiene-modified phenol resin, phenol aralkyl resin, naphthol aralkyl resin, terpene-modified phenol resin, triphenol methane resin, etc. And these may be used alone or as a mixture. The equivalent ratio of the number of epoxy groups in the epoxy resin to the number of phenolic hydroxyl groups in the phenol resin is preferably in the range of 0.8 to 1.2.

As the curing accelerator used in the present invention, any one can be used as long as it promotes the curing reaction between the epoxy group and the phenolic hydroxyl group, and those generally used for a sealing material can be widely used. For example, 1,8-diazabicyclo (5,4,0) undecene-7, 2-methylimidazole, triphenylphosphine, and the like,
These may be used alone or as a mixture.

Examples of the inorganic filler used in the present invention include fused silica, spherical silica, crystalline silica, secondary aggregated silica, porous silica, silica obtained by grinding secondary aggregated silica or porous silica, alumina, and silicon nitride. And the like,
These may be used alone or as a mixture. Particularly, fused silica and crystalline silica are preferable. The shape of the particles may be crushed or spherical, but spherical fused silica is preferred from the viewpoint of the balance between the flow characteristics, mechanical strength, and thermal characteristics. Further, a material which has been surface-treated with a silane coupling agent or the like in advance may be used. The content of the inorganic filler is preferably 70 to 95% by weight in the entire epoxy resin composition from the balance between moldability and reliability.

The component (E) used in the present invention comprises Si atom 1
The ion trapping material is coated with an organosilicon compound to which one or more alkyl groups are directly bonded. Examples of the organosilicon compound in which one or more alkyl groups are directly bonded to one Si atom include, for example, methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, aminopropyltrimethoxysilane, mercaptopropyltriethoxysilane, Examples include, but are not limited to, silane coupling agents such as ureidopropyltriethoxysilane and silicone oils such as dimethylpolysiloxane and methylphenylpolysiloxane. These may be used alone or as a mixture, or a silane coupling agent and a silicone oil may be used in combination. Particularly, it is preferable to use silicone oil, and dimethylpolysiloxane is more preferable. Examples of the ion scavenger include hydrotalcite compounds and fired products thereof, and Bi, Sb, and Zr hydroxides and oxides. When these ion trapping materials trap ionic impurities, they are replaced with hydroxide ions or the like in the molecule or have a structure that absorbs ionic impurities, and traps and inactivates ionic impurities. Therefore, when incorporated in the epoxy resin composition, it plays a role in suppressing corrosion of the semiconductor circuit due to ionic impurities and improving the humidity resistance reliability. Among these ion scavengers, the compound represented by the general formula (1) among the calcined products of hydrotalcite compounds has a structure in which an anion is absorbed in itself when anion impurities are trapped, An anion trapping ability is higher than a hydrotalcite compound, and an epoxy resin composition containing the compound is preferable because corrosion due to anionic impurities is suppressed and improvement in moisture resistance reliability is observed. The compound represented by the general formula (1) is represented by Mg _a Al _b (OH) _c (CO ₃ ) _d [a,
b, c, and d are positive numbers not less than 0.1)], but are obtained by calcining the hydrotalcite compound when the calcining temperature is less than 300 ° C.
O _2, not progress de H ₂ O is, spinel without exceeding the ion trapping ability of 900 ℃ (MgAl ₂ O ₄₎ since the generating, the firing temperature is required to be 300 to 900 ° C.. A particularly preferable firing temperature is 400 to 600 ° C, and a firing time is 1 to 20.
Time.

However, some ion-trapping materials have many gaps between particles due to their molecular structure, and such ion-trapping materials have high hygroscopicity under humid conditions and deteriorate solder crack resistance. Was one of the causes. Among them, the calcined product of the hydrotalcite compound is manufactured by calcining the hydrotalcite compound to remove CO ₃ and OH, so that the gap between the particles is large and even if the product is left in the air. In the solder crack resistance test under humid conditions, the solder crack resistance was greatly reduced. Therefore, in the present invention, in order not to adversely affect the epoxy resin composition, not to expose the particles of the ion-trapping material to the surface, and to impart hydrophobicity, the ion-trapping material is used per one Si atom of the present invention. An attempt was made to directly cover with an organosilicon compound having one or more alkyl groups bonded to suppress the moisture absorption of the ion trapping material. As a result, the moisture absorption of the cured product of the epoxy resin composition was significantly reduced even under high humidity, and the solder crack resistance was improved. Despite being coated, the ion-capturing ability was not changed, and the epoxy resin composition containing the same was able to secure the moisture resistance reliability and improve the solder crack resistance.
The content of the organosilicon compound in the component (E) is 0.1
-10% by weight is preferred. If it is less than 0.1% by weight, the effect of suppressing the hygroscopicity is small, and if it exceeds 10% by weight, not only the effect of ion trapping is reduced, but also the ion trapping material is agglomerated and dispersibility is lowered, which is not preferable. . As a method of coating the ion capturing material with the organosilicon compound,
For example, a method in which the ion trapping material is dispersed in water and stirred, and a method of adding the solution of the organosilicon compound, a method of spraying the solution of the organosilicon compound to the ion trapping material in a spray form, and the like, It is not limited to these. In particular, a method in which the surface of the ion capturing material is uniformly coated is preferable.

The particle size distribution of the component (E) of the present invention is as follows:
The average particle size is 0.5 to 15 μm, and the particle size is 0.2 μm or less.
The content of 0% by weight or less and the particle size of 20 μm or more is preferably 3% by weight or less, and out of this range, an epoxy resin composition excellent in fluidity and filling property cannot be obtained. The particle size distribution of the component (E) in the present invention is measured by a laser diffraction particle size distribution analyzer (manufactured by Horiba, Ltd., LA-
500). (E) As for the compounding quantity of a component, 0.05-2 weight% is preferable in all the epoxy resin compositions. If the content is less than 0.05% by weight, the effect of trapping ions is small, so that the moisture resistance reliability is not improved. If the content is more than 2% by weight, the cured product of the epoxy resin composition has an increased hygroscopic property, and the solder crack resistance is poor. It is not preferable because it lowers.

The epoxy resin composition of the present invention comprises (A)
In addition to the component (E), if necessary, a coupling agent, a coloring agent such as carbon black and red iron oxide, a release agent such as a natural wax and a synthetic wax, a low stress additive such as a silicone oil, a flame retardant, and a rubber. Various additives and the like may be appropriately compounded. The epoxy resin composition of the present invention comprises (A)
(E) The components and other additives are sufficiently and uniformly mixed at room temperature using a mixer or the like, then melt-kneaded with a hot roll or a kneader, cooled, and pulverized. In order to manufacture a semiconductor device by encapsulating an electronic component such as a semiconductor element using the epoxy resin composition of the present invention, the molding may be performed by a molding method such as a transfer mold, a compression mold, and an injection mold.

Hereinafter, the present invention will be described in detail with reference to examples.
The present invention is not limited by these examples. The mixing ratio is by weight. << Example 1 >> Biphenyl type epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd., melting point 110 ° C., epoxy equivalent 195) 7.2 parts by weight Phenol aralkyl resin (softening point 80 ° C., hydroxyl equivalent 174) 5.9 parts by weight Part 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) 0.2 part by weight Spherical fused silica (average particle size 22 μm, specific surface area 2.2 m ² / g) 85.0 parts by weight Mg _0.7 Al _0.3 O _1.15 surface coated with dimethylpolysiloxane (average particle size 10 μm, particle size 0.2 μm or less 3% by weight, particle size 20 μm or more 0% by weight, dimethylpolysiloxane content 0.5) % By weight, hereinafter referred to as M1) 0.5 part by weight Carbon black 0.3 part by weight Carnauba wax 0.3 part by weight Other additives 0.6 part by weight using a mixer It was mixed with warm, then kneaded with a roll at 70 to 110 ° C., followed by cooling then pulverizing, to obtain an epoxy resin composition. The obtained epoxy resin composition was evaluated by the following method. Table 1 shows the results.

Evaluation method: Moisture absorption: Mold temperature was measured using a low-pressure transfer molding machine.
175 ° C, injection pressure 9.8 × 10⁶Pa, curing time 1
A 50mm diameter, 3mm thick disk is formed in 20 seconds.
The treatment was performed at 175 ° C. for 8 hours as a stock. Moisture absorption treatment
Before and in an environment of 85 ° C and 85% relative humidity for 168 hours
After the treatment, the change in weight is measured, and the moisture absorption is shown as a percentage.
Was. The unit is%.-Solder crack resistance: Use a low-pressure transfer molding machine
Mold temperature 175 ° C, injection pressure 9.8 × 10⁶Pa,
80pQFP (thickness 2.0mm,
(6 mm × 6 mm). Post cure
6 packages treated at 175 ° C. for 8 hours
Treated in an environment of 5 ° C. and 60% relative humidity for 168 hours
Thereafter, an IR reflow treatment (240 ° C.) was performed. After processing
Use an ultrasonic flaw detector to check for internal peeling and cracks.
The number of defective packages was counted. Bad package
When n is n, it is displayed as n / 6.・ Moisture resistance reliability: Use a low pressure transfer molding machine to
Mold temperature 175 ° C, injection pressure 9.8 × 10⁶Pa, during curing
16 SOP (1.95 mm thick, chip
(3.5 mm × 3.0 mm). Post cue
The treatment was performed at 175 ° C. for 8 hours. Pressure cooker
Kerr test (125 ° C, pressure 2.2 × 10 ^FivePa)
Measure the open failure of the circuit and express it as the failure occurrence time.
Was. The unit is time.

Examples 2 to 4, Comparative Examples 1 to 4 Epoxy resin compositions were prepared in the same manner as in Example 1 according to the formulations in Tables 1 and 2, and evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2. The other ion trapping materials used in other than Example 1 are as follows. Bi (OH) _0.7 (NO ₃ ) _0.3 coated with dimethylpolysiloxane (average particle size 10 μm, particle size 0.2 μm or less 3% by weight, particle size 20 μm or more 0% by weight, dimethylpolysiloxane Content: 0.5% by weight, hereinafter referred to as M2), Mg _0.7 Al _0.3 O _1.15 (average particle size 10 μm, particle size 0.1 μm)
3% by weight is 2% or less, and 0% by weight is 20% or more.
Bi (OH) _0.7 (NO ₃ ) _0.3 (average particle size 10 μm,
3% by weight when the particle size is 0.2 μm or less and 0 when the particle size is 20 μm or more.
weight%. Hereinafter, referred to as M4)

[Table 1]

[0017]

[Table 2]

[0018]

According to the present invention, an epoxy resin composition for semiconductor encapsulation and a semiconductor device having both excellent solder crack resistance and excellent moisture resistance reliability can be obtained.

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Claims (4)

[Claims] 1. An epoxy resin, (B) a phenolic resin, (C) a curing accelerator, (D) an inorganic filler, and (E) one or more alkyl groups bonded directly to one Si atom. An epoxy resin composition for semiconductor encapsulation comprising, as an essential component, an ion scavenger coated with an organosilicon compound. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the ion scavenger is a compound represented by the general formula (1). Mg _x Al _y O _z (1) (where x, y, and z are positive numbers of 0.1 or more) 3. An organosilicon compound having one or more alkyl groups bonded directly to one Si atom in the component (E),
0.1 to 10% by weight, and the component (E) has an average particle size of 0.5 to 15 μm, a particle size of 0.2 μm or less is 10% by weight or less, a particle size of 20 μm or more is 3% by weight or less, and The epoxy resin composition for semiconductor encapsulation according to claim 1 or 2, wherein the component (E) is 0.05 to 2% by weight of the total epoxy resin composition. 4. A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition according to claim 1, 2 or 3.