JPH08337709A - Epoxy resin composition for semiconductor sealing and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a semiconductor sealing epoxy resin composition which gives cured products excellent in high temperature shelf properties, flame retardance and reflow crack resistance and is useful for semiconductor devices or the like by compounding an epoxy resin, a curing agent, a specific aromatic phosphate esters and an inorganic filler into the composition.

SOLUTION: The resin composition capable of removing or reducing compounding of antimony trioxide and a bromine compound and giving cured products good in high temperature shelf properties, flame retardance and reflow crack resistance can be obtained by compounding (A) 20-80 pts.wt. epoxy resin (e.g. a novolak type epoxy resin or the like); (B) 20-80 pts.wt. curing agent (e.g. a phenol novolak resin or the like); (C) 0.1-50 pts.wt. compound of formula I [wherein R¹ and R² are each a 1-4C alkyl; R³ and R⁴ are each H or a 1-4C alkyl; R⁵ is H, OH or a group of formula II; R⁶ and R⁷ are each H, OH, a group of formula II, phenyl, phenoxy, phenylthio, phenylsufonyl, benzoyl or a group of formula III (wherein R⁸ and R⁹ are each H or methyl); and n is 0-10]; and (D) 200-1,200 pts.wt. inorganic filler (e.g. fused silica or the like).

COPYRIGHT: (C)1996,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a semiconductor which does not contain antimony trioxide and a bromine compound, or at least the amount thereof can be reduced, and which provides a cured product excellent in high temperature storage property, flame retardancy and reflow crack resistance. The present invention relates to an encapsulating epoxy resin composition and a semiconductor device encapsulated with a cured product of the resin composition.

[0002]

2. Description of the Related Art In recent years,
Surface mount packages have become mainstream as semiconductor devices have been mounted at high densities. When mounting these surface mount type packages, the package is exposed to high temperature (215 to 26
0 ° C.), the package encapsulated with the conventional encapsulant has a chip-encapsulant interface that peels off during mounting, or cracks occur in the encapsulant portion. The problem is that reliability cannot be guaranteed.

Under the circumstances as described above, at present, a sealing material using a biphenyl type epoxy resin having low water absorption and excellent reflow crack resistance as an epoxy resin is being widely used for surface mounting.

However, when this biphenyl type epoxy resin is used, the reflow crack resistance is superior to the conventional encapsulant due to the effects of low water absorption, high temperature and low elasticity, while the glass transition temperature is remarkably higher than the conventional one. Since it is low, there is a big problem that it is inferior to the conventional encapsulant in reliability tests such as high temperature storage characteristics.

The reason why a defect occurs when left at high temperature is that an intermetallic compound is generated at the joint between the Al electrode of an IC and a gold wire during high temperature exposure, which increases the resistance value and further breaks the wire. Is. This intermetallic compound is used as a flame retardant in a resin composition containing Br ⁻ or S.
It is known that the presence of b ³⁺ promotes its production. In this case, a combination of brominated epoxy resin and antimony trioxide is generally used as the flame retardant, and therefore reducing the compounding amount of this flame retardant is also effective for improving the high temperature storage property.

However, even if the content of the flame retardant is reduced, the high temperature storage property is only slightly improved, and the flame retardancy standard (UL-0 V-0 class) cannot be satisfied. appear.

Therefore, it is desirable that the flame retardant antimony trioxide and bromine compound are not contained in the resin composition at least, or at least the amount thereof is reduced.

The present invention has been made in view of the above circumstances, and it is possible to reduce the amount of antimony trioxide and bromine compound used or eliminate their use.
An object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation that gives a cured product excellent in flame retardancy and reflow crack resistance, and a semiconductor device encapsulated with the cured product of the resin composition.

[0009]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies to achieve the above object, the present inventors have found that the following general formula (1) is used as a flame retardant in an epoxy resin composition. Even if the epoxy resin composition for semiconductor encapsulation using the compound of 1 contains no bromine compound such as Sb ₂ O ₃ or brominated epoxy resin, it gives a cured product excellent in flame retardancy and reflow crack resistance, Further, they have found that the invention is excellent in high-temperature storage property, and that a semiconductor device encapsulated with a cured product of the resin composition is particularly excellent in high-temperature reliability, and thus completed the present invention.

[0010]

[Chemical 4]

That is, the present invention comprises: (a) 20 to 80 parts by weight of an epoxy resin, (b) 20 to 80 parts by weight of a curing agent, (c) 0.1 to 50 parts by weight of the compound of the general formula (1), (D) An inorganic filler (200 to 1200 parts by weight) is contained, and an epoxy resin composition for semiconductor encapsulation, and a semiconductor device encapsulated with a cured product of this composition are provided. To aim.

The epoxy resin composition of the present invention is used as a substitute for a bromine compound such as a brominated epoxy resin or antimony trioxide, which has been conventionally used as a flame retardant, and has the above formula (1).
The phosphorus-containing compound having the specific structure of No. 2 does not contain a source of Br ⁻ , Sb ³⁺ that promotes the formation of intermetallic compounds when left at high temperature, and thus the semiconductor encapsulated with the cured product of the resin composition is used. The device shows high temperature reliability equivalent to that of a resin composition containing no flame retardant, and also shows excellent flame retardancy and reflow crack resistance. Furthermore, since the composition does not contain Sb ₂ O ₃ and a bromine compound which adversely affect the human body or cause environmental pollution, it is possible to provide a resin composition which is industrially particularly useful. .

The present invention will be described in more detail below.
The epoxy resin which is the first essential component of the epoxy resin composition for semiconductor encapsulation of the present invention includes a biphenyl type epoxy resin, a novolac type epoxy resin, a polyfunctional type epoxy resin, an alicyclic epoxy resin, and a heterocyclic type epoxy resin. , Bisphenol A type epoxy resin, naphthalene ring-containing epoxy resin, halogenated epoxy resin and the like. Among these, a biphenyl type epoxy resin is preferable in order to satisfy the reflow crack resistance, and it is preferable to use another epoxy resin in combination with this if necessary, but a brominated epoxy resin is not included or a small amount described later is used. It is preferably used.

Examples of such a biphenyl type epoxy resin include those represented by the following general formula (6).

[0015]

Embedded image (In the formula, R is a hydrogen atom, a halogen atom or a carbon number of 1 to 5
Is an alkyl group, and q is an integer of 0-5. )

The epoxy resin curing agent is not particularly limited in molecular structure, molecular weight and the like as long as it is a compound having two or more functional groups capable of reacting with the epoxy resin. For example, bisphenol A-type and F-type phenol resins, phenol novolac resins, triphenol alkane-type phenol resins and polymers thereof, biphenyl-type phenol resins, dicyclopentadiene-phenol novolac resins, phenol aralkyl-type phenol resins, naphthalene ring-containing phenol resins. In addition to phenol resins such as alicyclic phenol resins and heterocyclic phenol resins, amine-based curing agents, acid anhydride-based curing agents, etc. may be mentioned, and one of these may be used alone or two or more thereof may be used in combination. Can be used.

The ratio of the epoxy resin to the curing agent used is 20-80 parts by weight of the epoxy resin and 20-80 parts of the curing agent.
By weight, the total amount is 100 parts by weight, and the amount of the curing agent to be added is, for example, when a phenol resin is used, the molar ratio between the amount of epoxy groups in the epoxy resin and the phenolic hydroxyl group in the phenol resin is 0. It is preferable to add 0.5-2, more preferably 0.5-1.5, and even more preferably 0.8-1.5.

Further, in the present invention, it is preferable to use a curing catalyst in order to accelerate the curing reaction between the epoxy resin and the curing agent. The curing catalyst is not particularly limited as long as it accelerates the curing reaction, and examples thereof include triphenylphosphine, tributylphosphine, tri (p-methylphenyl) phosphine, tri (p-methoxyphenyl) phosphine, tri (p-ethoxyphenyl). ) Phosphine, triphenylphosphine / triphenylborate, phosphorus compounds such as tetraphenylphosphine / tetraphenylborate, triethylamine, benzyldimethylamine, α-methylbenzyldimethylamine, 1,8-diazabicyclo (5.4.0) undecene A tertiary amine compound such as -7, an imidazole compound such as 2-methylimidazole, 2-phenylimidazole, and 2-phenyl-4-methylimidazole can be used.

The amount of the curing catalyst blended is preferably 0.01 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, based on 100 parts by weight of the total amount of the epoxy resin and the curing agent.

The present invention uses, as a flame retardant, the following general formula (1):
The compound is used.

[0021]

[Chemical 6]

Here, as the alkyl group having 1 to 4 carbon atoms, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, sec-butyl group, tert-butyl group and the like are shown. . Further, R ^{1 to} R ⁷ have the same meanings as described above, but R ¹ and R ² are preferably the same alkyl group, and more preferably both are tert-butyl groups. R ³ and R ⁴ are both preferably a methyl group, and R 3
⁵ is preferably a hydrogen atom. At least one of R ⁶ and R ⁷ is preferably a hydroxyl group or a glycidyl ether group, and such a compound can react with an epoxy resin component to form a part of the resin skeleton.

As the compound of the above formula (1), a compound of the following formula (2) or (3) is particularly preferably used.

[0024]

[Chemical 7] (M is an integer of 1 to 11.)

It should be noted that any of the compounds of formula (1)
The total amount of chlorine ions and alkali metal ions extracted at 0 ° C / 100% RH is less than 50 ppm, preferably 10 p
It is preferably less than pm, and when it is 50 ppm or more, it may adversely affect the high temperature storage property and the moisture resistance.

The addition amount of the flame retardant of the general formula (1) of the present invention is 100 in total of the epoxy resin and the phenol resin.
0.1 to 50 parts by weight, preferably 1 to 3 parts by weight
0 parts by weight. If it is less than 0.1 part by weight, sufficient flame retardancy may not be obtained, and if it exceeds 50 parts by weight, the viscosity during molding may be high and moldability may be poor.

Further, in the present invention, it is preferable to blend a phosphorus-containing compound of the following formula (4) or (5) as a flame retardant auxiliary together with the compound of the general formula (1). When the compound of the following formula (4) or (5) is used in combination with the compound of the above general formula (1), the flame retardancy standard ( UL-94 V-
0) can be achieved more easily, which is preferable.

[0028]

Embedded image

The addition amount of the flame retardant aid of the above formula (4) or (5) is 10 in total of the epoxy resin and the phenol resin.
0.1 to 50 parts by weight is preferable with respect to 0 parts by weight. 0.
If it is less than 1 part by weight, sufficient flame retardancy may not be obtained, and if it exceeds 50 parts by weight, the viscosity at the time of molding may be high and the moldability may be deteriorated.

The mixing ratio of the compound of the general formula (1) to the compound of the above formula (4) or (5) is preferably 0.2 to 2 with respect to the compound 1 of the general formula (1) as a weight ratio. .

In the epoxy resin composition of the present invention, it is more preferable not to contain a bromine compound such as antimony trioxide and a brominated epoxy resin. It may be contained in a small amount within a range that does not impair the object of the present invention. In this case, the contents of antimony trioxide and bromine compound are
Antimony trioxide is 2 parts by weight or less, especially 1 part by weight or less, and bromine compound is 1 part by weight or less, especially 0.5% as bromine, based on 100 parts by weight of the total amount of the epoxy resin and the curing agent.
It is less than or equal to parts by weight.

As the inorganic filler to be added to the epoxy resin composition of the present invention, those usually added to the epoxy resin composition can be used. For example, fused silica, silicas such as crystalline silica, alumina, silicon nitride,
Aluminum nitride, boron nitride, titanium oxide,
Glass fiber etc. are mentioned. The average particle size and shape of these inorganic fillers are not particularly limited, but those having an average particle size of 5 to 40 μm are preferable in terms of moldability and fluidity. The filling amount of the inorganic filler is preferably 200 to 1200 parts by weight based on 100 parts by weight of the total amount of the epoxy resin and the phenol resin. If the amount is less than 200 parts by weight, the expansion coefficient becomes large, the stress applied to the semiconductor element increases, and the element characteristics may be deteriorated. In addition, even in the high temperature storage characteristic, a large stress is applied to the generated intermetallic compound to deteriorate the characteristics. There is a case to let. On the other hand, if it exceeds 1200 parts by weight, the viscosity at the time of molding becomes high, and the moldability may deteriorate. The inorganic filler is preferably surface-treated in advance with a silane coupling agent or the like in order to increase the bonding strength between the resin and its surface.

If desired, the composition of the present invention may further contain various other additives. For example, thermoplastic resins, thermoplastic elastomers, organic synthetic rubbers, low stress agents such as silicones, waxes such as carnauba wax, fatty acids such as stearic acid and metal salts thereof, pigments such as carbon black, cobalt blue and red iron oxide, and grease. A silane coupling agent such as cidoxypropyltrimethoxysilane, a surface treating agent such as alkyl titanates, an antiaging agent, and an additive such as a halogen trapping agent can be added.

The epoxy resin composition of the present invention is prepared by uniformly stirring and mixing predetermined amounts of the above-mentioned components in the production thereof,
A kneader, a heat roll, which has been heated to 70 to 95 ° C in advance,
It can be obtained by a method such as kneading with an extruder or the like, cooling and pulverizing.

The epoxy resin composition for semiconductor encapsulation of the present invention thus obtained can be effectively used for encapsulation of various semiconductor devices. In this case, molding is carried out by a conventional molding method, For example, transfer molding, injection molding, casting method or the like can be adopted, but the epoxy resin composition of the present invention is effective for the low pressure transfer molding method. The molding temperature of the epoxy resin composition of the present invention is preferably 150 to 180 ° C. for 30 to 180 seconds, and the post cure is preferably 150 to 180 ° C. for 2 to 16 hours.

[0036]

Industrial Applicability The epoxy resin composition of the present invention can eliminate or reduce the blending of antimony trioxide and bromine compound, and gives a cured product excellent in high temperature storage property, flame retardancy and reflow crack resistance. The semiconductor device encapsulated with the cured product of the epoxy resin composition of the present invention has particularly excellent high temperature reliability.

[0037]

EXAMPLES The present invention will be described below in detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, all parts are parts by weight.

[Examples 1 to 6 and Comparative Examples 1 to 3] The components shown in Table 1 were uniformly melt-mixed with a hot double roll, cooled and pulverized to obtain epoxy resin compositions for semiconductor encapsulation. .

[0039]

[Table 1]

Next, regarding these compositions, the following (a) to
Various tests of (f) were conducted. Table 2 shows the results. (A) Spiral flow value 175 ° C, 70k using a mold conforming to the EMMI standard
It was measured under the conditions of g / cm ² and molding time of 120 seconds. (B) Gelation time The gelation time of the composition was measured on a hot plate at 175 ° C. (C) Molding hardness 175 ° C, 70 kg / cm according to JIS-K6911
^{2. The} hardness at the time of molding a bar of 10 × 4 × 100 mm was measured with a Barcol hardness tester under the condition that the molding time was 120 seconds. (D) Reflow crack A flat package of 14 × 20 × 2.1 mm was molded under the conditions of 175 ° C., 70 kg / cm ² , and a molding time of 120 seconds, and post-cured at 180 ° C. for 4 hours to 85 ° C.
After leaving it in a thermo-hygrostat of / 85% RH for 72 hours to absorb moisture, it was immersed in a solder bath at a temperature of 240 ° C. for 30 seconds, and cracks outside the package were observed. (E) Flame retardancy Based on UL-94 standard, a plate having a thickness of 1/16 inch was molded and the flame retardancy was examined. (F) High temperature storage characteristics A simulated element in which aluminum wiring is formed on a silicon chip and a partially alloyed 42 alloy lead frame are bonded with a gold wire having a thickness of 30 μm, and 175 ° C. and 70 kg.
14-pin DIP was molded under the conditions of / cm ² and molding time of 120 seconds. Post-cure at 180 ° C for 4 hours in a dryer at 200 ° C for a predetermined time (0h, 96h, 168
h) After standing, the cured resin was dissolved in fuming nitric acid, and the shear strength of the bonding portion on the chip side was measured.

[0041]

[Table 2]

From the results shown in Table 2, it is recognized that the epoxy resin composition containing the phosphorus-based flame retardant of the present invention gives a cured product excellent in high temperature storage property, flame retardancy and reflow crack resistance.

Reference Example 1 Synthesis of Compound of Formula (2) 2,5-Di-tert-butylhydroquinone 3.78
kg (17 mol), ethyl acetate 3 kg, pyridine 0.1
70 kg was mixed under dry nitrogen in a reaction vessel having a condenser and an exhaust gas removing unit, and thoroughly stirred. This mixture was heated to an internal temperature of 60 ° C., and phosphorus trichloride (4.67 kg, 34 mol) was added at 60 ° C. over 30 minutes. The resulting mixture was refluxed for about 1 hour (internal temperature: about 74 ° C). Then, a solution prepared by dissolving 4.15 kg (34 mol) of 2,6-dimethylphenol in 3 kg of ethyl acetate was used at an internal temperature of 75 to 7
Add at 7 ° C. over 1 hour. The resulting brown solution was stirred under reflux for 1.5 hours and then cooled to about 25 ° C. Hydroquinone 3.74 kg (34 mol) was replaced with ethyl acetate 9
A solution of 2 kg of acetone and 2.7 kg of acetone was added dropwise at 25 ° C. over about 2 minutes, and triethylamine 4.66 was added.
kg (46 mol) was added and the resulting mixture was stirred for a further 30 minutes. 3.86 kg of 30% H ₂ O ₂ was added over about 1 hour, the temperature in the reaction vessel was maintained at 30 to 35 ° C., and the mixture was stirred for another 2 hours. Twice with 1N-HCl, 0.1
After washing once with N-HCl, the organic phase was separated, dried over sodium sulfate and the solvent removed under vacuum. Finally,
The obtained solid was further dried under high vacuum for 30 minutes to obtain 8.33 kg (theoretical yield: 71%) of the target substance. From GPC, Mn = 700, Mw = 2947,
The elemental analysis values were as follows. The chlorine content was 0.3% or less.

[0044]

Reference Example 2 Synthesis of Compound of Formula (3) 2,5-Di-tert-butylhydroquinone 22.2
2 g (0.1 mol), 17.5 g of ethyl acetate and 1.05 g of pyridine were mixed under dry argon in a reaction vessel having a condenser and an exhaust gas removing unit, and thoroughly stirred. 27.5 g of phosphorus trichloride (0.2
Mol) was added. Slowly heat the resulting mixture,
It was kept under reflux for about 1 hour. Then, 24.4 g (0.2 mol) of 2,6-dimethylphenol was added to ethyl acetate 17.
A solution dissolved in 5 g was added over about 10 minutes. The resulting brown solution was stirred under reflux for 1.5 hours and then cooled to room temperature. 1,3,5-trihydroxybenzene 25.
A solution prepared by dissolving 22 g (0.2 mol) in 52 g of ethyl acetate and 15.5 g of acetone was added dropwise over about 15 minutes while cooling with ice, and further 27.35 g of triethylamine (0.3.
(27 mol) was added over 30 minutes under ice cooling, and the resulting mixture was stirred for another 30 minutes. 30% H ₂ O ₂ 22.67 g
Was slowly added with cooling and the mixture was stirred for a further 2 hours. Then, the target compound was isolated and dried in the same manner as in Reference Example 1.

The softening point of the obtained brown resinous substance is 15
It was 6.6 to 171.2 ° C, and the elemental analysis values were as follows. The hydroxyl group content was 5.65 meq / g.

[0047]

Front page continued (72) Inventor Eiichi Asano 1 Hitomi, Osamu Matsuida-cho, Usui-gun, Gunma Prefecture Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratories (72) Takayuki Aoki Inoue Matsuida-cho, Usui-gun, Gunma Prefecture View No. 1 10 Shin-Etsu Chemical Co., Ltd., Silicone Electronic Materials Research Laboratory (72) Inventor Toshio Shiobara Osamu Matsuida Town, Usui District, Gunma Prefecture Hitomi No. 10 Shin-Etsu Chemical Co., Ltd. Silicone Electronic Materials Research Laboratory (72) Inventor Peter Hurli Murmerweg, Himmelried, Switzerland 415 (72) Inventor Wolfgang Schaf, Glenzach Wieren, Germany, Lüttler Ring 11 Che (72) Inventor, Tadashi Okada, Stalenmattstrasse 45, Switzerland

Claims (6)

[Claims] 1. (a) Epoxy resin 20 to 80 parts by weight, (b) Curing agent 20 to 80 parts by weight, (c) Compound of the following general formula (1) 0.1 to 50 parts by weight, (d) Inorganic An epoxy resin composition for semiconductor encapsulation, comprising 200 to 1200 parts by weight of a filler. Embedded image 2. The composition according to claim 1, wherein a compound represented by the following formula (2) or (3) is used as the compound of general formula (1). Embedded image (M is an integer of 1 to 11.) 3. The following formula (4) or (5) as a flame retardant aid.
The composition according to claim 1 or 2, which is blended with a phosphorus-containing compound represented by. Embedded image 4. The composition according to claim 1, wherein a biphenyl type epoxy resin is used as the epoxy resin. 5. The antimony trioxide content is 2 parts by weight or less and the bromine content is 1 part by weight or less based on 100 parts by weight of the total amount of the epoxy resin and the curing agent.
The composition according to any one of 1. 6. A semiconductor device encapsulated with a cured product of the epoxy resin composition for semiconductor encapsulation according to any one of claims 1 to 4.