JP2002348356A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

(57) [Problem] To provide an epoxy resin composition having characteristics excellent in adhesion, room temperature storage, moldability, flame retardancy and solder stress resistance. (A) a phenol aralkyl type epoxy resin having a diphenylene skeleton, (B) a phenol aralkyl resin having a diphenylene skeleton, (C) an all inorganic substance,
(D) Tetraphenylphosphonium as a curing accelerator
Tetrakis (1-naphthoyloxy) borate is an essential component, and all inorganic substances are 87 to 94 in all epoxy resin compositions.
An epoxy resin composition for encapsulating a semiconductor, which is contained in a weight percentage.

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 room temperature storage properties and moldability, and a semiconductor device having excellent flame retardancy and solder stress resistance.

[0002]

2. Description of the Related Art Conventionally, semiconductor devices such as diodes, transistors, and integrated circuits are mainly sealed with an epoxy resin composition. However, these epoxy resin compositions are provided with flame retardancy. And an antimony compound such as antimony trioxide and antimony tetroxide. However, development of an epoxy resin composition excellent in flame retardancy without using a bromine-containing organic compound and an antimony compound is desired from the viewpoint of environment and hygiene. In addition, when a semiconductor device is mounted on a printed circuit board, lead-containing solder (tin-lead alloy) is used. Similarly, lead-containing solder (tin-lead alloy) is used from the viewpoint of environment and sanitation. It is desired not to use it. The melting point of solder containing lead (tin-lead alloy) is 183 ° C
The soldering temperature during mounting is 220 to 240 ° C. In contrast, a solder containing no lead, such as a tin-silver alloy, has a high melting point and a temperature of 260 ° C. during soldering.
Since the temperature is about ℃, development of an epoxy resin composition having more excellent soldering stress resistance is desired. Also, during the soldering process, the semiconductor device is exposed to a high temperature, and due to the stress when the absorbed moisture explosively evaporates, peeling occurs at the interface between the semiconductor element or the lead frame and the cured product of the epoxy resin composition. Since the peeling causes cracks in the semiconductor device and significantly lowers the reliability, an epoxy resin composition having excellent adhesion between a semiconductor element or a lead frame and a cured product of the epoxy resin composition is required. .

In order to improve the flame retardancy and solder stress resistance, it is necessary to increase the amount of the inorganic filler and to reduce the content of the resin component. There is a method using a resin. At present, an epoxy resin composition using a low-viscosity crystalline epoxy resin without using a flame retardant and highly filled with an inorganic filler or an epoxy resin composition using a highly flame-retardant resin, and various flame retardants are used. The epoxy resin composition used has been proposed, but no epoxy resin composition which completely satisfies good moldability or solder stress resistance has yet been proposed. Further, in a process of sealing a semiconductor device with an epoxy resin composition, it is required to shorten a molding time as one of means for increasing production efficiency. For this purpose, rapid curing at the time of molding is required. When a conventional curing accelerator is added in an amount sufficient to achieve rapid curing at the time of molding, there is a problem that the storage stability of the epoxy resin composition at room temperature is extremely reduced.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to an epoxy resin composition and solder stress resistance excellent in adhesion to semiconductor elements and lead frames, room temperature storage properties and moldability, and a bromine-containing organic compound and antimony compound. It is intended to provide a semiconductor device which is excellent in flame retardancy without containing any.

[0005]

Means for Solving the Problems The present invention provides [1] (A)
An epoxy resin represented by the general formula (1), (B) a phenol resin represented by the general formula (2), (C) all inorganic substances,
(D) A semiconductor encapsulation characterized by comprising a curing accelerator represented by the formula (3) and / or the general formula (4) as an essential component, and the total amount of inorganic substances is 87 to 94% by weight in the total epoxy resin composition. Epoxy resin composition for use, [2] (A) epoxy resin represented by general formula (1), (B) phenolic resin represented by general formula (2), (C) all inorganic substances, (D) formula (3) And / or a curing accelerator represented by the general formula (4) as an essential component, the total amount of the inorganic substance is 87 to 94% by weight in the total epoxy resin composition, and the bromine-containing organic compound and the antimony compound are each a flame retardant component. An epoxy resin composition for semiconductor encapsulation, which is 1000 ppm or less for each

[0006]

Embedded image (R1 and R2 are alkyl groups having 1 to 4 carbon atoms, which may be the same or different. A is an integer of 0 to 3, b is 0
An integer from 4 to 4. n is an average value and a positive number of 1 to 5)

[0007]

Embedded image (R1 and R2 are alkyl groups having 1 to 4 carbon atoms, which may be the same or different. A is an integer of 0 to 3, b is 0
An integer from 4 to 4. n is an average value and a positive number of 1 to 5)

[0008]

Embedded image

[0009]

Embedded image (X1, X2, X3 and X4 are a monovalent organic group or a monovalent aliphatic group having an aromatic ring or a heterocyclic ring, which may be the same or different from each other.
Y2, Y3 and Y4 are a monovalent organic group or a monovalent aliphatic group having an aromatic ring or a heterocyclic ring, and at least one of them has at least one proton which can be released outside the molecule. The proton donor is a group that releases one proton, and they may be the same or different from each other. )

[3] The epoxy resin represented by the general formula (1) is an epoxy resin represented by the formula (5):
Item or the epoxy resin composition for semiconductor encapsulation according to item [2],

[0011]

Embedded image (N is an average value and a positive number from 1 to 5)

[4] The epoxy resin composition for semiconductor encapsulation according to [1] or [2], wherein the phenolic resin represented by the general formula (2) is a phenolic resin represented by the following formula (6):

[0013]

Embedded image (N is an average value and a positive number from 1 to 5)

[5] A semiconductor device characterized by sealing a semiconductor element using the epoxy resin composition for semiconductor sealing according to any one of [1] to [4]. .

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS General formula (1) used in the present invention
Has a hydrophobic and rigid diphenylene skeleton between epoxy groups, and a cured product of the epoxy resin composition using the epoxy resin has a low moisture absorption rate and a glass transition temperature (hereinafter, referred to as Tg). Low in a high temperature region exceeding the above, and has excellent adhesion to a semiconductor element and a lead frame.
In addition, it has a characteristic that heat resistance is high in spite of low crosslink density. Therefore, the semiconductor device sealed with the resin composition using this epoxy resin can have high reliability even under the soldering process at the time of mounting.

In the general formula (1), n is an average value, preferably a positive number of 1 to 5, particularly preferably 1 to 3. n = 1
If it is less than this, the curability of the epoxy resin is undesirably reduced. If n exceeds 5, the viscosity of the resin increases and the fluidity of the resin composition decreases, which is not preferable. General formula (1)
By adjusting the amount of the epoxy resin indicated by the symbol, the solder stress resistance can be maximized. To bring out the effect of solder stress resistance,
It is desirable that the epoxy resin represented by the general formula (1) contains 30% by weight or more, preferably 50% by weight or more of the total epoxy resin. If the amount is less than 30% by weight, the solder stress resistance may be insufficient. The epoxy resin represented by the general formula (1) may be used in combination with another epoxy resin as long as the intrinsic properties of the epoxy resin are not impaired. When used in combination, it is desirable to use a monomer, oligomer, or polymer having an epoxy group in the molecule, which has as low a viscosity as possible,
For example, phenol novolak epoxy resin, cresol novolak epoxy resin, biphenyl epoxy resin, bisphenol epoxy resin, stilbene epoxy resin, triphenolmethane epoxy resin, naphthol epoxy resin, naphthalene epoxy resin, alkyl-modified triphenolmethane Epoxy resin, triazine nucleus-containing epoxy resin, dicyclopentadiene-modified phenolic epoxy resin, and the like. However, when another low-viscosity epoxy resin is used in combination, the moldability may be inferior. Therefore, the moldability can be improved by using the curing accelerator of the present invention described later.

The phenol resin represented by the general formula (2) used in the present invention has a hydrophobic and rigid diphenylene skeleton between phenol groups, and a cured product of the resin composition using the phenol resin has a moisture absorption rate. , Low elastic modulus in a high temperature range exceeding Tg, and excellent adhesion to a semiconductor element or a lead frame. In addition, it has a characteristic that heat resistance is high in spite of low crosslink density. Therefore, a semiconductor device sealed with a resin composition using this epoxy resin can have high reliability even under soldering during mounting.

In the general formula (2), n is an average value, preferably a positive number of 1 to 5, particularly preferably 1 to 3. n = 1
If it is less than this, the curability of the epoxy resin is undesirably reduced. If n exceeds 5, the viscosity of the resin increases and the fluidity of the resin composition decreases, which is not preferable. General formula (2)
By adjusting the amount of the phenol resin used, the solder stress resistance can be maximized. To bring out the effect of solder stress resistance,
It is desirable that the phenolic resin represented by the general formula (2) be contained in an amount of 30% by weight or more, preferably 50% by weight or more of all phenolic resins. If the amount is less than 30% by weight, the solder stress resistance may be insufficient. The phenol resin represented by the general formula (2) used in the present invention may be used in combination with another phenol resin as long as the properties of the phenol resin are not impaired.
When used in combination, it is desirable to use, as a whole, monomers, oligomers and polymers having a phenolic hydroxyl group in the molecule, which have the lowest possible viscosity, such as phenol novolak resin, cresol novolak resin, naphthol aralkyl resin, and triphenolmethane resin. And terpene-modified phenolic resins, dicyclopentadiene-modified phenolic resins, and the like. The equivalent ratio of the epoxy group of all epoxy resins used in the present invention to the phenolic hydroxyl group of all phenolic resins is preferably 0.5 to 2, and more preferably 0.7 to 1.5. If the ratio is out of the range of 0.5 to 2, the moisture resistance, the curability and the like are undesirably reduced.

The total inorganic substance used in the present invention is a sum of an inorganic filler generally used in a sealing material and an inorganic substance such as an antimony compound as a flame retardant and an inorganic ion exchanger added as necessary. is there. The type of the inorganic filler used in the present invention is not particularly limited, and examples thereof include fused silica, fused spherical silica, crystalline silica, secondary aggregated silica, alumina, titanium white, and aluminum hydroxide. Is preferred. As the shape of the fused spherical silica, it is preferable that the shape is infinitely spherical and the particle size distribution is broad in order to improve fluidity. The content of all inorganic substances is preferably 87 to 94% by weight in the whole epoxy resin composition. If the content is less than 87% by weight, the cured product of the epoxy resin composition will not have low moisture absorption properties and will have insufficient soldering stress resistance, and will have a bromine such as a brominated ortho-cresol novolak type epoxy resin and a brominated bis-A type epoxy resin. Containing organic compound and antimony trioxide,
Unless a flame retardant such as an antimony compound such as antimony tetroxide is added, the flame retardancy is insufficient, which is not preferable. If the content exceeds 94% by weight, the fluidity of the resin composition is lowered, and there is a possibility that incomplete filling or the like may occur at the time of molding, or an inconvenience such as deformation of a gold wire in the semiconductor device due to an increase in viscosity may occur.

In the present invention, the flame retardant of the bromine-containing organic compound and the antimony compound is 1000 ppm or less for each flame retardant component. Even if the flame retardant is not intentionally added, it is difficult to set the level to be 0 ppm at the raw material or in the production stage for economic reasons.
The function of the present invention is effective regardless of ppm or 0 ppb. It is preferable that the inorganic filler used in the present invention is sufficiently mixed in advance. If necessary, the inorganic filler may be treated in advance with a coupling agent, an epoxy resin or a phenol resin, and may be used. The method of the treatment includes a method of removing the solvent after mixing with a solvent or a method of directly filling the inorganic filler. There is a method of adding to a material and treating using a mixer.

The curing accelerator represented by the formula (3) used in the present invention does not exhibit catalytic activity at normal temperature, so that the curing reaction of the epoxy resin composition does not proceed, and the catalytic activity is exhibited at a high temperature during molding. Once exhibited, they exhibit a higher catalytic activity than conventional curing accelerators, and have the characteristic of highly curing epoxy resin compositions. The curing accelerator represented by the general formula (4) used in the present invention comprises phosphonium borate. However, in the general formula (4), X1, X2, X3 and X4 of the phosphonium group are a monovalent organic group or a monovalent aliphatic group having an aromatic ring or a heterocyclic ring, and are the same as each other. May also be different. Such phosphonium groups include, for example, tetraphenylphosphonium, tetratolylphosphonium,
Tetraethylphenylphosphonium, tetramethoxyphenylphosphonium, tetranaphthylphosphonium, tetrabenzylphosphonium, ethyltriphenylphosphonium, n-butyltriphenylphosphonium, 2-hydroxyethyltriphenylphosphonium, trimethylphenylphosphonium, methyldiethylphenylphosphonium, methyldiallylphenylphosphonium And tetra-n-butylphosphonium. In the general formula (4), X1, X2, X3 and X4 are particularly preferably a monovalent organic group having an aromatic ring, and the melting point of the phosphonium borate represented by the general formula (4) is not particularly limited. However, the temperature is preferably 250 ° C. or lower from the viewpoint of uniform dispersion in the epoxy resin composition. In particular, phosphonium borate having a tetraphenylphosphonium group has good compatibility with epoxy resins and phenol resins, and can be suitably used.

In the general formula (4), Y of the borate group
1, Y2, Y3 and Y4 are a monovalent organic group or a monovalent aliphatic group having an aromatic ring or a heterocyclic ring, and at least one of them has at least a proton capable of being released outside the molecule. The proton donor having one proton is a group formed by releasing one proton, and Y1, Y2, Y3 and Y4
May be the same or different from each other. Examples of such a proton donor that provides a borate group include aromatic carboxylic acids such as benzoic acid, 1-naphthoic acid, 2-naphthoic acid, phthalic acid, trimellitic acid, pyromellitic acid, and 2,6-naphthalenedicarboxylic acid. Acids and phenols,
Biphenol, bisphenol A, bisphenol F,
Phenolic compounds such as 1-naphthol, 2-naphthol, and polyphenols are good and can be suitably used.
When the curing accelerator represented by the general formula (4) used in the present invention is incorporated into an epoxy resin composition, it does not exhibit catalytic activity at room temperature, so that the curing reaction of the epoxy resin does not proceed, and The catalyst activity is exhibited at a high temperature, and once developed, shows a stronger catalytic activity than conventional curing accelerators, and highly cures the epoxy resin composition. The compounding amount of the curing accelerator represented by the formula (3) and / or the formula (4) is preferably 0.1 to 0.5% by weight based on the entire epoxy resin composition.

The epoxy resin composition of the present invention comprises (A)
In addition to the component (D), if necessary, an inorganic ion exchanger such as bismuth oxide hydrate, a coupling agent such as γ-glycidoxypropyltrimethoxysilane, a coloring agent such as carbon black and red iron, silicone oil, A low stress component such as silicone rubber, a natural wax, a synthetic wax, a higher fatty acid and a metal salt thereof, or a mold release agent such as paraffin, and various additives such as an antioxidant may be appropriately compounded. The epoxy resin composition of the present invention comprises (A)
(D) A component, other additives, etc. are mixed at normal temperature using a mixer, melt-kneaded with a kneader such as a roll, kneader, extruder or the like, 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, it is sufficient to cure and mold by a molding method such as a transfer mold, a compression mold, and an injection mold.

[0024]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. The mixing ratio is by weight. Example 1 The following composition: An epoxy resin represented by the formula (5) (softening point: 60 ° C., epoxy equivalent: 275 g / eq) 4. 78 parts by weight Phenol resin represented by formula (6) (softening point: 65 ° C., hydroxyl equivalent: 200 g / eq) 3.52 parts by weight Curing accelerator represented by formula (7): 0.30 parts by weight

[0025]

Embedded image

90.00 parts by weight of fused spherical silica Carnauba wax 0.30 parts by weight Inorganic ion exchanger 0.50 parts by weight γ-glycidoxypropyltrimethoxysilane 0.30 parts by weight Carbon black 0.30 parts by weight at room temperature And mixed at 70-120 ° C with a mixer.
The mixture was kneaded using a shaft roll, cooled and pulverized to obtain an epoxy resin composition. The obtained epoxy resin composition was evaluated by the following method. Table 1 shows the results.

Evaluation method Spiral flow: Measurement was performed using a mold for measuring spiral flow according to EMMI-1-66 at a mold temperature of 175 ° C., an injection pressure of 7.4 MPa, and a curing time of 2 minutes. The unit is cm. Curing Torque: Using a curast meter (manufactured by Orientec Co., Ltd., JSR curast meter IVPS type), a torque at a mold temperature of 175 ° C. and 90 seconds after the start of heating was determined.
The torque in the curast meter is a parameter of curability, and the larger the numerical value, the better the curability. The unit is N · m. Storage at 25 ° C .: After storing the epoxy resin composition at 25 ° C. for 3 days, the spiral flow is measured and expressed as a percentage of the spiral flow immediately after the preparation of the epoxy resin composition. Flame retardancy: The epoxy resin composition is made into tablets, and using a low-pressure transfer molding machine, the mold temperature is 175 ° C., the injection pressure is 7.4 MPa, the curing time is 2 minutes, the length is 127 mm, the width is 12.7 mm, and the thickness is 1. 6mm molded product is molded and UL
A flame retardancy test was performed according to -94. Moisture resistance: The epoxy resin composition is tableted, and using a low-pressure transfer molding machine, the mold temperature is 180 ° C., the injection pressure is 9.8 MPa, and the curing time is 144 pLQFP in 1 minute.
(Package size: 20 × 20mm, thickness 1.4m)
m, silicon chip size: 9.0 × 9.0 mm, passivation of silicon chip: SiN, lead frame: copper with copper flash plating). Package 8 treated at 175 ° C for 8 hours as post cure
The individual pieces were treated for 168 hours in an environment of 85 ° C. and 60% relative humidity, and then subjected to IR reflow treatment (260 ° C.). The presence or absence of peeling inside after the treatment was observed with an ultrasonic flaw detector, and those with peeling from the internal element were judged as x, and those without peeling were judged as o. Solder stress resistance: The epoxy resin composition is tableted, and the mold temperature is set to 180 using a low-pressure transfer molding machine.
14 ° C. under the condition of 9.8 ° C., injection pressure of 9.8 MPa and curing time of 1 minute.
4pLQFP (package size: 20 × 20mm, thickness 1.4mm, silicon chip size: 9.0 × 9.0)
mm, passivation of silicon chip: SiN, lead frame: copper with copper flash plating). Eight packages treated at 175 ° C. for 8 hours as post-curing were placed in an environment of 85 ° C. and 60% relative humidity for 1 hour.
After the treatment for 68 hours, an IR reflow treatment (260 ° C.) was performed. The presence or absence of internal cracks after the treatment was observed with an ultrasonic flaw detector, and the number of defective packages was counted. When the number of defective packages is n, n / 8 is displayed. Table 1 shows the evaluation results.

Examples 2 and 3 and Comparative Examples 1 to 5 An epoxy resin composition was obtained in the same manner as in Example 1 according to the composition shown in Table 1, and evaluated in the same manner as in Example 1. Table 1 shows the evaluation results. In Examples 2 and 3, and Comparative Examples 2, 4, and 5, the curing accelerator of Formula (3) was used. The DBU of Comparative Example 3 is
1,8-diazabicyclo (5,4,0) undecene-7
It is. In Comparative Examples 4 and 5, a phenol aralkyl resin (manufactured by Mitsui Chemicals, Inc., XL-225, softening point 75 ° C,
A hydroxyl equivalent of 174 g / eq) was used.

[0029]

[Table 1]

[0030]

According to the present invention, it is possible to stably store at room temperature for a long period of time without curing, and when heated during molding, a rapid curing reaction develops, resulting in good moldability. Thus, an epoxy resin composition exhibiting adhesiveness is obtained, and a semiconductor device using the same is excellent in soldering stress resistance and excellent in flame retardancy without containing a bromine-containing organic compound or an antimony compound.

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Claims (5)

[Claims] (A) an epoxy resin represented by the general formula (1), (B) a phenol resin represented by the general formula (2),
(C) All inorganic substances, (D) a curing accelerator represented by the formula (3) and / or the general formula (4) as an essential component, and the total inorganic substance is 87 to 94% by weight in the total epoxy resin composition. Characteristic epoxy resin composition for semiconductor encapsulation. (A) an epoxy resin represented by the general formula (1), (B) a phenol resin represented by the general formula (2),
(C) all inorganic substances, (D) a curing accelerator represented by the formula (3) and / or the general formula (4) as an essential component, and the total inorganic substance is 87 to 94% by weight of the total epoxy resin composition; An epoxy resin composition for semiconductor encapsulation, wherein the content of the organic compound and the antimony compound is 1000 ppm or less for each flame retardant component. Embedded image (R1 and R2 are alkyl groups having 1 to 4 carbon atoms, which may be the same or different. A is an integer of 0 to 3, b is 0
An integer from 4 to 4. n is an average value and a positive number of 1 to 5) (R1 and R2 are alkyl groups having 1 to 4 carbon atoms, which may be the same or different. A is an integer of 0 to 3, b is 0
An integer from 4 to 4. n is an average value and a positive number of 1 to 5) Embedded image (X1, X2, X3 and X4 are a monovalent organic group or a monovalent aliphatic group having an aromatic ring or a heterocyclic ring, which may be the same or different from each other.
Y2, Y3 and Y4 are a monovalent organic group or a monovalent aliphatic group having an aromatic ring or a heterocyclic ring, and at least one of them has at least one proton which can be released outside the molecule. The proton donor is a group that releases one proton, and they may be the same or different from each other. ) 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the epoxy resin represented by the general formula (1) is an epoxy resin represented by the following formula (5). Embedded image (N is an average value and a positive number from 1 to 5) 4. The phenol resin represented by the general formula (2) is a phenol resin represented by the formula (6).
Or the epoxy resin composition for semiconductor encapsulation according to 2. Embedded image (N is an average value and a positive number from 1 to 5) 5. A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition for semiconductor encapsulation according to claim 1.