JP2001122946A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition for sealing semiconductors good in curability, having high potentiality and good in shelf life. SOLUTION: This epoxy resin composition is characterized as comprising (A) an epoxy resin, (B) a curing agent, (C) an inorganic filler and (D) a microencapsulted catalyst containing an imidazole compound and/or an organophosphorus compound and having 0.5-50 μm average particle diameter and >=70 wt.% total amount of elution of the catalyst from the microcapsule in o-cresol based on the total amount of the catalyst contained in the microcapsule at 30 deg.C for 15 min.

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 having high potential, good preservability, excellent adhesiveness to metals and the like, and giving high heat strength, and a cured product thereof. The present invention relates to a semiconductor device sealed with a.

[0002]

2. Description of the Related Art In recent years,
The mainstream of semiconductor devices is resin-sealed type diodes, transistors, ICs, LSIs, and super LSIs. Epoxy resins have better moldability, adhesiveness, electrical properties, mechanical properties, moisture resistance, etc. than other thermosetting resins. Because of its superiority, it is common to seal a semiconductor device with an epoxy resin composition.

[0003] More recently, the semiconductor industry has been trying to improve the package production cycle in order to reduce costs, and has demanded rapid curing properties of epoxy resin compositions. However, when the amount of the catalyst is increased to give the quick-curing property, the thickening and curing are fast, so that the flow of the gold wire during molding and the unfilling are likely to occur. Further, when the amount of the catalyst is increased, there is also a problem that the storage stability of the epoxy resin composition is significantly reduced.

Therefore, as disclosed in JP-A-3-182520, a technique for microencapsulating one of the constituent components of the composition has been developed. However, in conventional microcapsules, it has been difficult to greatly increase the reaction rate due to the thick shell of the capsule and the low concentration of the catalyst. By increasing the reaction rate and increasing the productivity,
On the contrary, there are many problems that the storage stability is not improved as expected, and it has not been put to practical use until now.

[0005] The present invention has been made in view of the above circumstances,
By using a microcapsule catalyst that has good dispersibility in resin and high reactivity, it has excellent latent and preservability, and furthermore, an epoxy resin composition and a cured product thereof excellent in cured product strength and adhesiveness. It is an object to provide a sealed semiconductor device.

[0006]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that an epoxy resin containing an epoxy resin, a curing agent, an inorganic filler, and a curing catalyst. The resin composition is a microcapsule catalyst containing an imidazole compound and / or an organic phosphorus compound as a curing catalyst, and has an average particle size of 0.1.
When using a microcapsule catalyst having a particle size of 5 to 50 μm and having an elution amount of the catalyst from the microcapsules in o-cresol of not less than 70% by weight of the total amount of the catalyst contained in the microcapsules at 30 ° C. for 15 minutes. , Can achieve both curability and preservability, high potential, good preservability, while exhibiting excellent curability at the time of curing, the resulting epoxy resin composition has a cured product strength and The inventors have found that they have excellent adhesiveness and are suitable for semiconductor encapsulation, and have accomplished the present invention.

Accordingly, the present invention provides (A) an epoxy resin,
An epoxy resin composition comprising (B) a curing agent, (C) an inorganic filler, and (D) the microcapsule catalyst is provided. This epoxy resin composition is effective for semiconductor encapsulation, and therefore the present invention also provides a semiconductor device encapsulated with the cured product.

Hereinafter, the present invention will be described in more detail.
The epoxy resin (A) in the epoxy resin composition used in the present invention includes novolak type epoxy resins such as phenol novolak type epoxy resin and cresol novolak type epoxy resin, aralkyl type epoxy resin, biphenyl skeleton-containing aralkyl type epoxy resin, Biphenyl type epoxy resin, heterocyclic type epoxy resin, naphthalene ring-containing epoxy resin, bisphenol A type epoxy compound,
Examples thereof include bisphenol type epoxy resins such as bisphenol F type epoxy compounds, stilbene type epoxy resins, and the like, and one or more of these can be used in combination. Above all, it is preferable to use a polyfunctional epoxy resin as a measure against package warpage. Examples of the polyfunctional epoxy resin include those having the following structures. Among them, triphenolalkane epoxy resins such as triphenolmethane epoxy resin and triphenolpropane epoxy resin are preferable. Further, these polyfunctional epoxy resins and the epoxy resins exemplified above may be used in combination.

[0009]

Embedded image (Wherein, R is a hydrogen atom or a methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl,
It is a monovalent hydrocarbon group having 1 to 6 carbon atoms represented by an alkyl group such as a tert-butyl group, a pentyl group and a hexyl group. R 'is a hydrogen atom, a methyl group or an ethyl group, preferably a hydrogen atom. N is an integer of 0 to 6. )

Although any of the above epoxy resins can be used, from liquid to solid, those having a softening point of 50 to 120 ° C. and an epoxy equivalent of 100 to 400 are preferred. When an epoxy resin having a softening point lower than 50 ° C is used, not only does the glass transition temperature of the cured product decrease, but burrs and voids are easily generated during molding,
If the softening point is higher than 120 ° C., the viscosity may be too high to make molding impossible.

When the epoxy resin is used for semiconductor encapsulation, the content of hydrolyzable chlorine is 1,000 ppm or less.
In particular, it is preferable that the content be 500 ppm or less, and that sodium and potassium be 10 ppm or less, respectively. If a semiconductor device is sealed with a resin in which hydrolyzable chlorine exceeds 1,000 ppm or sodium and potassium exceed 10 ppm, and the semiconductor device is left under high temperature and high humidity for a long time, moisture resistance may be deteriorated. .

The curing agent (B) for the epoxy resin is preferably a phenol resin having at least two phenolic hydroxyl groups in one molecule. Specifically as such a curing agent, a phenol novolak resin, a novolak type phenol resin such as a cresol novolak resin,
Para-xylylene-modified novolak resin, meta-xylylene-modified novolak resin, ortho-xylylene-modified novolak resin, bisphenol-A resin, bisphenol-type resin such as bisphenol-F resin, biphenyl-type phenol resin, resole-type phenol resin, phenol-aralkyl resin, triphenol-alkane type Phenolic resins such as resins and their polymers, naphthalene ring-containing phenolic resins,
A dicyclopentadiene-modified phenol resin is exemplified, and any phenol resin can be used.

In consideration of heat resistance, package warpage, and moldability among these phenolic resins, use of a phenol novolak resin or a triphenolalkane type and a polymer thereof is preferred. Further, an amine-based curing agent or an acid anhydride-based curing agent may be used alone or in combination with the phenol resin.

These hardeners have a softening point of 60 to 60.
Those having a temperature of 150 ° C, particularly 70 to 130 ° C, are preferred.
Moreover, the thing of 90-250 is preferable as a hydroxyl equivalent. Further, when such a phenol resin is used for encapsulating a semiconductor, sodium and potassium are preferably set to 10 ppm or less, and the semiconductor device is sealed using a substance exceeding 10 ppm, and is subjected to high temperature and high humidity for a long time. When the semiconductor device is left, deterioration of moisture resistance may be promoted.

The amount of the curing agent is not particularly limited, but is the curing amount of the epoxy resin. When a phenolic resin is used, the molar ratio of the phenolic hydroxyl group in the curing agent to the epoxy group in the epoxy resin is preferably in the range of 0.5 to 1.5, particularly preferably in the range of 0.8 to 1.2. is there.

As the inorganic filler (C), those usually blended in an epoxy resin composition can be used. This inorganic filler is compounded to reduce the expansion coefficient of the sealing material and reduce the stress applied to the semiconductor element. Specifically, fused silica and crystalline silica having a crushed or spherical shape are mainly used. In addition, alumina, silicon nitride, aluminum nitride and the like can be used.

It is recommended to use a blend of a sphere and a crushed product, or to use only a sphere in order to achieve both low expansion of the cured product and moldability. In addition, it is preferable that the above-mentioned inorganic filler is surface-treated with a silane coupling agent before use.

The average particle size of these inorganic fillers is 1 to 40.
μm, particularly preferably 5 to 30 μm. In addition,
In the present invention, the average particle diameter can be determined, for example, as a weight average value (or median diameter) by a laser light diffraction method.

The amount of the inorganic filler is 100 to 1,000 parts, preferably 100 to 1,000 parts, preferably 100 parts (parts by weight, hereinafter the same) of the epoxy resin (A) and the curing agent (B). 250 to 1,000 parts, more preferably 350 to
900 copies. The filling amount is 70% of the total composition.
It is preferably at least 75% by weight, especially at least 75% by weight. If the filling amount is too small, the expansion coefficient increases, the stress applied to the semiconductor element increases, and the element characteristics may deteriorate. The upper limit of the filling amount is usually 92% by weight or less.

The epoxy resin composition of the present invention is a microcapsule catalyst containing an imidazole compound and / or an organic phosphorus compound as a curing catalyst, having an average particle size of 0.5 to 50 μm and an o- The amount of catalyst eluted from the microcapsules in cresol is 30 ° C, 1
In 5 minutes, a microcapsule catalyst that is 70% by weight or more of the total amount of the catalyst contained in the microcapsules is blended. In the curing catalyst microcapsules, an imidazole compound or an organic phosphorus compound is used as a catalyst in the microcapsules.

As the imidazole compound, those represented by the following general formula (1) can be used.

[0022]

Embedded image (Wherein, R ¹ and R ² represent a hydrogen atom or an alkyl group such as a methyl group, an ethyl group, a hydroxymethyl group, a phenyl group,
A substituted alkyl group, a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 6, such as an aryl group; R ³ represents an alkyl group such as a methyl group, an ethyl group, a phenyl group, an allyl group; And represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 6 carbon atoms, such as an alkenyl group and an aryl group, and R ⁴ represents a hydrogen atom, a methyl group, an ethyl group, a cyanoethyl group, a benzyl group or the like. An alkyl group of
A substituted alkyl group, an aralkyl group or the like having 1 to 12 carbon atoms,
It is preferably a substituted or unsubstituted monovalent hydrocarbon group of 1 to 6, or a group represented by the following formula (2). Examples of the substituted monovalent hydrocarbon group include hydroxy-substituted and cyano-substituted groups. )

[0023]

Embedded image

Specifically, 2-methylimidazole, 2
-Ethyl-4-methylimidazole, 2-phenylimidazole, 1-benzyl-2-phenylimidazole,
1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-allyl-4,5-
Diphenylimidazole, 2,4-diamino-6
[2′-Methylimidazolyl- (1) ′]-ethyl-S
-Triazine, 2,4-diamino-6- [2'-ethyl-4'-methylimidazolyl- (1) ']-ethyl-S
-Triazine, 2,4-diamino-6- [2′-methylimidazolyl- (1) ′]-ethyl-S-triazine isocyanuric acid adduct, 2-phenyl-4-methyl-5
-Hydroxymethylimidazole and the like.

Examples of the organic phosphorus compounds include, for example, triphenylphosphine, tributylphosphine, tri (p
Triorganophosphines such as -methylphenyl) phosphine, tri (nonylphenyl) phosphine and diphenyltolylphosphine; salts of triorganophosphines such as triphenylphosphine / triphenylborane with triorganoboran; tetraphenylphosphonium / tetraphenylborate; And organoorganic phosphines such as salts of tetraorganophosphonium with tetraorganoborate. Among them, those represented by the following general formula (3) are particularly preferable.

[0026]

Embedded image (In the formula, R ⁵ is a hydrogen atom, or an alkyl or alkoxy group having 1 to 4 carbon atoms.)

Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, and a tert-butyl group. Examples of the alkoxy group include a methoxy group and an ethoxy group. .
R ⁵ is preferably a hydrogen atom or a methyl group.
Examples of the compound of the formula (3) include the following.

[0028]

Embedded image

The microcapsules used in the present invention are (meth) acrylic monomers, for example, alkyl esters having 1 to 8 carbon atoms such as acrylic acid esters, itaconic acid esters, methacrylic acid esters, crotonic acid esters, and alkyl esters thereof. Having an alkyl group having a substituent such as an allyl group; monofunctional olefin (or vinyl) monomers such as styrene, α-methylstyrene, acrylonitrile, methacrylonitrile, and vinyl acetate; (Meth) acrylate, polyethylene glycol di (meth) acrylate, divinylbenzene,
An imidazole compound or an organic phosphorus compound is contained in a polymer of a polyfunctional olefin (or vinyl) monomer such as bisphenol A di (meth) acrylate or methylenebis (meth) acrylamide. In addition, among the above polymers, a polymer of a (meth) acrylate monomer is preferable.

There are various methods for producing microcapsules containing a curing catalyst such as the above-mentioned imidazole compound and organic phosphorus compound of the present invention. Usually, it can be produced by a conventionally known method such as a suspension polymerization method and an emulsion polymerization method.

In this case, in order to obtain a high-concentration microcapsule catalyst from the molecular structure of a generally used catalyst, the total amount of the above-mentioned monomers used is about 10 to 200 parts per 10 parts of the curing catalyst. And desirably 10 to 100
Parts, more preferably 20 to 50 parts. If it is less than 10 parts, it may be difficult to sufficiently impart the potential, and if it exceeds 200 parts, the ratio of the catalyst becomes low, so that a large amount must be used to obtain sufficient curability. , May be economically disadvantageous. That is, the concentration of the curing catalyst contained in the microcapsules is about 5
-50% by weight, preferably about 9-50% by weight, more preferably about 17-33% by weight.

The average particle size of the microcapsules obtained by such a method is 0.5 to 50 μm. Desirably, it is 3 to 25 μm. If it is less than 0.5 μm, the particle size is too small, and if a large amount of microcapsules is blended, the viscosity becomes high and, in some cases, the potential may become insufficient. On the other hand, if it exceeds 50 μm, the particle size is too large, and gate clogging or the like may be caused during molding.

As the microcapsules, those having the following properties are used. That is, 1 g of the microcapsules containing the curing catalyst was weighed, mixed with 30 g of o-cresol, left at 30 ° C., and the eluted catalyst was quantified by gas chromatography. 70% by weight or more of the total amount of the catalyst contained in the microcapsules (ie, 7
0-100% by weight). If the content is less than 70% by weight, when molding a semiconductor device using an epoxy resin composition, a molding time of at least 175 ° C. for 1 minute is required,
Productivity may decrease. Preferably, the elution amount is 7
5% by weight or more (that is, 75 to 100% by weight).

The amount of the microcapsule-type curing catalyst of the present invention to be added to the epoxy resin composition is preferably 0.5 to 15 parts based on 100 parts in total of the components (A) and (B).
Preferably it is 1 to 10 parts. If the amount is less than 0.5 part, sufficient curability cannot be obtained, and if the amount exceeds 15 parts, the curability is sufficient, but the cost may be increased and disadvantageous.

In the composition of the present invention, in addition to the microencapsulated curing catalyst of the component (D), a conventionally known non-microencapsulated curing catalyst (curing accelerator) similar to the above is used in combination. Is also good. In this case, the weight ratio of (non-microencapsulated curing catalyst / curing catalyst-containing microcapsules) is used in a ratio of 0 to 0.5, preferably 0 to 0.2, and more preferably 0 to 0.1. It is desirable.

The composition of the present invention may contain, if necessary, a silicone-modified copolymer or various organic synthetic resins to impart flexibility or toughness to the cured product of the composition or to impart adhesiveness. Thermoplastic resins such as rubber, styrene-butadiene-methyl methacrylate copolymer, styrene-ethylene-butene-styrene copolymer, and fine powders such as silicone gel and silicone rubber can be added. Further, the surface of the inorganic filler may be treated with a two-pack type silicone rubber or silicone gel. The above-mentioned silicone-modified copolymer and styrene-butadiene-methyl methacrylate copolymer are effective in reducing the stress of the epoxy resin.

The amount of the silicone-modified copolymer and / or thermoplastic resin used as the above-mentioned low stress agent is usually 0 to 10% by weight, especially 0.2 to 10% by weight of the whole epoxy resin composition.
Preferably it is 5% by weight. If the amount is more than 10% by weight, the mechanical strength may decrease.

Further, the composition of the present invention may contain a coloring agent such as carbon black, a brominated epoxy resin, a flame retardant such as antimony trioxide, a release agent, a coupling agent, and the like.

The epoxy resin composition containing the microcapsule-type curing catalyst of the present invention is prepared by blending an epoxy resin, a curing agent, an inorganic filler, and other additives at a predetermined composition ratio, and homogenizing the mixture by a dry mixer or the like. After that, the mixture is melt-kneaded by a hot roll, a kneader, an extruder or the like, then cooled and solidified, and pulverized to an appropriate size to obtain a molding material.

The thus obtained epoxy resin composition containing the microcapsule-type curing catalyst of the present invention can be effectively used for sealing various semiconductor devices. In this case, the most common method of sealing is used. Examples include a low-pressure transfer molding method. The molding temperature is usually 160 to 1
90 ° C.

[0041]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Examples and Comparative Examples Using the components shown in Tables 1 to 3, epoxy resin compositions were prepared according to a conventional method, and their performance was evaluated by the following methods. The results are shown in Tables 1 to 3. << Spiral Flow >> Molding was performed at 175 ° C. under a molding pressure of 70 kgf / cm ² , and measurement was performed. << Geling time and melt viscosity >> All were measured at 175 ° C. << Hot Hardness >> Using each epoxy resin composition
After a molded product having a size of 0 mm × 10 mm × 4 mm was cured at 175 ° C. for 40 seconds, the mold was quickly opened, and the hardness of the molded product was measured with a Barcol hardness meter. << Melt Viscosity >> The melt viscosity of each composition was measured at 175 ° C. using a Koka type flow tester equipped with a die having a nozzle diameter of 1 mm. << Preservation >> Put each epoxy resin composition in a closed container and place
It was left at 5 ° C. for 120 hours. Thereafter, the spiral flow was measured, and the rate of decrease was calculated from the initial value, and was used as storage data. << Moldability of QFP package >> Make a mini tablet with each compound, 14mm x 14mm x
Formability was confirmed using a 2.7 mm QFP package. Molding conditions: Molding temperature: 175 ° C Molding pressure: 70 kgf / cm ² Molding time: 40 seconds Preheat time: 5 seconds

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

Embedded image EOCN1020: Cresol novolak type epoxy resin, Nippon Kayaku Co., Ltd. TD2093: Phenol novolak resin, Dainippon Ink Co., Ltd. BREN-S: Brominated phenol novolak type epoxy resin, Nippon Kayaku Co., Ltd. KBM403: γ -Glycidoxypropyltrimethoxysilane, manufactured by Shin-Etsu Chemical Co., Ltd. TPP: triphenylphosphine, manufactured by Hokuko Chemical Co., Ltd.

[0047]

[Table 4] * Amount of catalyst eluted from microcapsules after 15 minutes at 30 ° C in o-cresol (% by weight)

[0048]

The epoxy resin composition for semiconductor encapsulation of the present invention has good curability, high potential, and good storage stability.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C09K 3/10 C09K 3/10 RZ H01L 23/29 H01L 23/30 R 23/31 (72) Inventor Yasuo Kimura Gunma 1-10 Hitomi, Matsuida-machi, Usui-gun, Japan Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (72) Inventor Takayuki Aoki 1-10 Hitomi, Matsuida-machi, Usui-gun, Gunma 1-10 Shin-Etsu Chemical Co., Ltd. Inside the laboratory (72) Inventor Kazuhiro Arai 1-10 Hitomi, Matsuida-cho, Usui-gun, Gunma Prefecture Inside Silicone Electronics Research Laboratory, Shin-Etsu Chemical Co., Ltd. (72) Inventor Hidenori Mizushima 1-inch Hitomi, Matsuida-cho, Usui-gun, Gunma Prefecture 10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Technology Laboratory

Claims (4)

[Claims] (1) an epoxy resin, (B) a curing agent,
(C) an inorganic filler, (D) an imidazole compound and / or
Or a microcapsule catalyst containing an organic phosphorus compound, having an average particle size of 0.5 to 50 μm, and o-
An epoxy resin composition comprising a microcapsule catalyst wherein the amount of the catalyst eluted from the microcapsules in cresol is at least 70% by weight of the total amount of the catalyst contained in the macrocapsules at 30 ° C. for 15 minutes. object. 2. The composition according to claim 1, which comprises (E) a curing catalyst which is not microencapsulated. 3. The composition according to claim 1, which is for semiconductor encapsulation. 4. A semiconductor device sealed with a cured product of the epoxy resin composition according to claim 3.