JP2003238660A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

(57) [Problem] To provide an epoxy resin composition having excellent fluidity and excellent solder crack resistance. SOLUTION: (A) An epoxy resin represented by the general formula (1) having a binuclear content of 10 to 60%, (B) a phenol resin, (C) an inorganic filler, and (D) a curing accelerator. An epoxy resin composition for semiconductor encapsulation, which is an essential component. Embedded image (Wherein, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, and may be the same or different from each other.
An integer of 3. n is an average value and a positive number of 1 to 10)

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor encapsulating epoxy resin composition and a semiconductor device having excellent fluidity and solder crack resistance.

[0002]

2. Description of the Related Art As a method for encapsulating semiconductor elements such as ICs and LSIs, transfer molding of an epoxy resin composition has been adopted as a method suitable for mass production at low cost for a long time, and the reliability of epoxy resin and curing agent is high. The improvement has been made by improving the phenol resin. However, in recent market trends of miniaturization, weight reduction, and high performance of electronic devices, semiconductor integration has advanced year by year, and surface mounting of semiconductor devices has been promoted. The demands on the composition are becoming more and more stringent. Therefore, there are some problems that cannot be solved by conventional epoxy resin compositions. In particular, under the current situation where surface mounting of semiconductor devices is becoming common, moisture-absorbed semiconductor devices are exposed to high temperatures during solder reflow processing, and peeling occurs at the interface between the semiconductor element or lead frame and the cured product of the epoxy resin composition. Problems such as cracks that occur in the cured product and that greatly deteriorate the reliability of the semiconductor device occur, and prevention of these defects, that is, improvement of solder resistance has become a major issue.

Further, as part of the elimination of environmentally hazardous substances, substitution of lead-free solder is being promoted. Since solder containing no lead has a higher melting point than conventional solder, the solder reflow temperature during surface mounting is higher by about 20 ° C. than before, and 260 ° C. is required. A semiconductor caused by peeling at each interface between a cured product of an epoxy resin composition and various plated joints on a semiconductor element, a lead frame, and an inner lead due to a change in the solder reflow temperature for handling solder that does not contain lead. The problem of device cracking has arisen.
These solder cracks and peeling are considered to be caused by moisture absorption by the semiconductor device itself before the solder reflow treatment, and the water vapor explosion under high temperature during the solder reflow treatment, which is caused by the epoxy resin composition in order to prevent it. Techniques such as imparting low hygroscopicity are often used. As a method for lowering the moisture absorption, for example, a method for lowering the moisture absorption of a cured product of an epoxy resin composition using an epoxy resin and a phenol resin having a low hygroscopic skeleton such as a phenyl or biphenyl skeleton, or a low viscosity type or low There is a method of using a melt-viscosity type epoxy resin and a phenol resin to increase the content of an inorganic filler in an epoxy resin composition to lower the moisture absorption of a cured product of the epoxy resin composition. However, even an epoxy resin composition using these methods alone or in combination is insufficient as a lead crack-free resin for solder crack resistance. For this reason, various improvements have been made for the purpose of improving the solder crack resistance during surface mounting at 260 ° C. However, none of them is a complete solution and further improvement is desired.

On the other hand, the epoxy resin composition contains a bromine atom-containing flame retardant as a flame retardant component and an antimony compound such as trioxide, tetraoxide or antimony pentoxide. However, with increasing awareness of environmental protection worldwide, there is an increasing demand for an epoxy resin composition having flame retardancy without using a bromine atom-containing organic compound or an antimony compound. Further, it is known that when the semiconductor device is stored at a high temperature of 150 to 200 ° C. for a long time, the flame retardant bromine atom or antimony compound causes an increase in the resistance value of the semiconductor element and a disconnection of the gold wire. From this viewpoint, development of an epoxy resin composition for semiconductor encapsulation that does not use a bromine atom-containing organic compound or an antimony compound is required.

[0005]

DISCLOSURE OF THE INVENTION The present invention has excellent fluidity, has improved adhesiveness to various members such as semiconductor elements and lead frames, and has a low elastic modulus to reduce stress.
Epoxy resin composition for semiconductor encapsulation having characteristics of significantly improving solder crack resistance of a semiconductor device when mounted on a substrate at ℃, and capable of maintaining flame retardancy without using a bromine atom-containing organic compound or antimony compound And a semiconductor device using the same.

[0006]

The present invention provides [1] (A)
An epoxy resin represented by the general formula (1) having a binuclear content of 10 to 60%, (B) a phenol resin, (C) an inorganic filler and (D) a curing accelerator as essential components. An epoxy resin composition for semiconductor encapsulation,

[0007]

[Chemical 2] (In the formula, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different from each other.
An integer of 3. n is an average value and is a positive number from 1 to 10)

[2] A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition as described in the item [1].

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A cured product of a resin composition using an epoxy resin having a structure represented by the general formula (1) and having a binuclear content of 10 to 60% has a glass transition temperature. It has a low elastic modulus in a high temperature range exceeding 100 ° C., low hygroscopicity, and can reduce thermal stress during soldering of surface mounting, and a cured product of a resin composition and a semiconductor element or a lead frame (42 alloy, It has excellent adhesiveness to a copper alloy), can suppress peeling and cracking of a cured product of the resin composition, and can obtain an excellent epoxy resin composition. In the present invention, an epoxy resin having a binuclear content of 10 to 60% is used, and the binuclear is n in the general formula (1).
= 1. GPC (Gel Per)
It is a value calculated in terms of polystyrene by means of the Meation Chromatography) method. That is, GPC column manufactured by Tosoh Corporation (G1000H × L: 1 piece, G
2000H × L: 2 present, G3000H × L: 1 present) using a flow rate of 1.0 cm ^3/60 sec, tetrahydrofuran as eluent, polystyrene measured using a differential refractometer detector under conditions of a column temperature 40 ° C. Calculated and calculated. When the binuclear content is less than the lower limit, the low elastic modulus effect at the time of heat of the cured product is small, the adhesiveness during solder reflow is poor, and the viscosity of the epoxy resin becomes too high. The fluidity is inferior, and it becomes difficult to increase the filling of the inorganic filler for further lowering the moisture absorption. If the content of the binuclear body exceeds the upper limit, the curability of the epoxy resin composition will decrease and the releasability will be poor. Further, there is a problem in that the strength at heat is lowered due to the decrease in the crosslink density, and the solder crack resistance is deteriorated. R in the general formula (1) represents hydrogen or an alkyl group having 1 to 4 carbon atoms, and may be the same or different from each other. a is 0
An integer of 3. n is an average value and is a positive number of 1 to 10. When n exceeds the upper limit, the viscosity of the resin increases, the fluidity of the resin composition at the time of molding deteriorates, and it becomes impossible to increase the filling of the inorganic filler for further lowering the moisture absorption.

The epoxy resin represented by the general formula (1) is
It may be used in combination with another epoxy resin as long as the characteristics are not impaired, but by adjusting the blending amount of this epoxy resin, solder crack resistance and flame retardancy can be maximized. In order to bring out these effects, the epoxy resin represented by the general formula (1) is contained in an amount of 30% by weight or more, preferably 50% by weight, based on the total amount of the epoxy resin.
The above use is desirable. If it is less than the lower limit, strength at high temperature and low hygroscopicity may not be sufficiently obtained, solder crack resistance may be insufficient, and flame retardancy tends to be lowered. The epoxy resin used in combination refers to all monomers, oligomers and polymers having an epoxy group in the molecule. For example, bisphenol A type epoxy resin, phenol novolac type epoxy resin, orthocresol novolac type epoxy resin, triphenol methane type epoxy resin, dicyclopentadiene modified phenol type epoxy resin, biphenyl type epoxy resin, stilbene type epoxy resin, bisphenol F type epoxy resin. Examples thereof include resins, phenol aralkyl (having a biphenylene skeleton) type epoxy resin, and naphthol type epoxy resin. These may be used alone or in combination.

As the phenol resin used in the present invention,
Monomers having a phenolic hydroxyl group in the molecule, oligomers, refers to polymers in general, for example, phenol novolac resin, cresol novolac resin, terpene modified phenol resin, dicyclopentadiene modified phenol resin, triphenol methane type resin, phenol aralkyl (phenylene skeleton, Resins having a biphenylene skeleton), naphthol aralkyl resins, and the like. These may be used alone or in combination. The equivalent ratio of the epoxy groups of all epoxy resins used in the present invention to the phenolic hydroxyl groups of all phenol resins is preferably 0.
5 to 2, and particularly preferably 0.7 to 1.5.
When it is out of the range of 0.5 to 2, moisture resistance, curability and the like are deteriorated, which is not preferable.

The inorganic filler used in the present invention is not particularly limited, and those generally used as sealing materials can be used. For example, fused silica, crystalline silica,
Secondary agglomerated silica, alumina, titanium white, silicon nitride, etc. may be mentioned, and these may be used alone or in combination. Among these, it is desirable to use fused silica having a high sphericity together with the total amount or partially crushed silica. The average particle size of the inorganic filler is 5 to 30 μm, and the maximum particle size is preferably 150 μm or less, and particularly the average particle size is 5 to 20 μm.
m, and the maximum particle size is preferably 74 μm or less. Also, the filling amount can be increased by mixing particles having different sizes. As the inorganic filler, one that has been surface-treated with a silane coupling agent or the like in advance may be used. Further, the content of the inorganic filler is 7 in the total epoxy resin composition.
0 to 94% by weight is preferred. Inorganic fillers that do not burn when heated take heat energy when exposed to flames,
It has the effect of improving the flame retardancy of the cured product of the epoxy resin composition. If the blending amount is less than the lower limit value, it becomes a cured product of an epoxy resin composition having a small heat capacity, and it tends to burn in a flame retardant test, which is not preferable. If it exceeds the upper limit, the fluidity at the time of molding becomes poor, which is not preferable.

The curing accelerator used in the present invention is not particularly limited as long as it can accelerate the reaction between the epoxy resin and the phenol resin. For example, 1,8-diazabicyclo (5,5)
4,0) amine compounds such as undecene-7 and tributylamine, organic phosphorus compounds such as triphenylphosphine and tetraphenylphosphonium tetraphenylborate salts, and imidazole compounds such as 2-methylimidazole. These may be used alone or in combination.

The epoxy resin composition of the present invention comprises (A)-
In addition to the component (D), if necessary, a silane coupling agent such as epoxysilane, a coloring agent such as carbon black,
Low stress components such as silicone oil and silicone rubber,
Various additives such as a natural wax, a synthetic wax, a higher fatty acid and a metal salt thereof or a releasing agent such as paraffin, and an antioxidant can be blended. The epoxy resin composition of the present invention is obtained by mixing components (A) to (D) and other additives at room temperature with a mixer, kneading with a kneader such as a roll or an extruder, and cooling and pulverizing. Obtained. By using the epoxy resin composition of the present invention to seal electronic components such as semiconductor elements and to manufacture semiconductor devices, transfer molding, compression molding, injection molding, etc. Good. Semiconductor devices to which the epoxy resin composition of the present invention is applied include QFP, SOP, TSOP, and BG.
A and others are not particularly limited.

[0015]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited thereto. The mixing ratio is parts by weight. Example 1 8.6 parts by weight of epoxy resin represented by the formula (2) (softening point 70 ° C., epoxy equivalent 280, binuclear content 29%)

[0016]

[Chemical 3]

[0017]   Phenol resin represented by formula (3) (softening point 77 ° C., hydroxyl equivalent 174)                                                             5.3 parts by weight

[0018]

[Chemical 4]

Fused spherical silica (average particle size 15 μm) 85.0 parts by weight 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) 0.2 parts by weight carbon black 0.4 parts by weight Carnauba wax (0.5 parts by weight) was mixed at room temperature with a mixer, kneaded with a twin-screw roll, cooled, and then ground to obtain an epoxy resin composition. The obtained epoxy resin composition was evaluated by the following methods. The results are shown in Table 1.

Evaluation method Spiral flow: Using a mold for spiral flow measurement according to EMMI-1-66, mold temperature 175 ° C.
It was measured at an injection pressure of 6.9 MPa and a curing time of 120 seconds.
The unit is cm. Bending strength during heating / Bending elastic modulus during heating: Mold temperature 175 ° C., injection pressure 6.9 MPa, curing time 120 seconds, 10 × 8
A 0 × 4 mm test piece was molded and post-cured at 175 ° C. for 8 hours, and the bending strength and elastic modulus at 240 ° C. were measured according to JIS K.
It measured according to 6911. The unit is N / mm ² . Curability: Epoxy resin composition, mold temperature 175 ° C., injection pressure 6.9 MPa, curing time 120 seconds, 10 × 8
A value obtained by molding a 0 × 4 mm test piece and measuring the Bacol hardness (No 935) 10 seconds after the mold was opened. Bacol hardness is an index of curability, and the larger the value, the better the curability. Moisture absorption rate: A low pressure transfer molding machine was used to mold a disk having a diameter of 50 mm and a thickness of 3 mm with a mold temperature of 175 ° C., an injection pressure of 7.5 MPa and a curing time of 120 seconds, and then 175 ° C.
It was post-cured in 8 hours, left for 168 hours in an environment of 85 ° C. and 85% relative humidity, and the weight change was measured to obtain the moisture absorption rate. The unit is% by weight. Solder resistance: 100-pin TQFP package (package size 14 x 14 mm, thickness 1.4 mm, silicon chip size 8.0 x 8.0 mm, lead frame made of 42 alloy) is injected at a mold temperature of 175 ° C. Pressure 7.5
Molded at 120 MPa for 8 seconds at 175 ° C
After a period of time, it was cured. The molded product package is left in an environment of 85 ° C and relative humidity of 85% for 168 hours, and then the molded product package is separately placed in a solder bath at 240 ° C and 260 ° C.
Soaked for 2 seconds. Twenty packages were used for each test. The packages were observed with a microscope, and the external crack ratio [(the number of cracked packages) / (total number of packages) × 100] was expressed in%. The ratio of the peeled area between the chip and the cured product of the epoxy resin composition was measured using an ultrasonic flaw detector, and the peeling rate [(peeled area) / (chip area) x 100] was expressed in%. Flame retardance: Using a transfer molding machine, mold temperature 17
5 ° C, injection pressure 7MPa, curing time 120 seconds, length 1
27 mm, width 12.7 mm, thickness 3.2 mm and 1.6 m
m, molded product, ΣF, Fm according to UL-94
The flame retardancy was determined by measuring ax. High-temperature storage characteristics: A 16-pin SOP in which a simulated element was wired with a gold wire having a diameter of 25 μm was treated in a high-temperature tank at 185 ° C., and the resistance value between pins was measured at regular intervals. 2 from the initial resistance value
The treatment time in the high temperature tank in which the number of packages in which the 0% resistance value increased was 8 or more out of 15 was indicated as the high temperature storage property. When this time is long, it shows that the high temperature stability is excellent.

Examples 2 to 8 and Comparative Examples 1 to 3 Compounds were prepared according to the formulations shown in Table 1, epoxy resin compositions were obtained in the same manner as in Example 1, and evaluated in the same manner as in Example 1.
The results are shown in Table 1. The raw materials used in Examples 2 to 8 and Comparative Examples 1 to 3 have the following properties. The epoxy resin represented by the formula (4) (softening point 58 ° C., epoxy equivalent 271,
Dinuclear content 55%)

[0022]

[Chemical 5]

Epoxy resin represented by the formula (5) (softening point 79 ° C., epoxy equivalent 297, binuclear content 14%)

[0024]

[Chemical 6]

Epoxy resin represented by the formula (6) (softening point 74 ° C., epoxy equivalent 291, binuclear content 31%)

[0026]

[Chemical 7]

Epoxy resin represented by the formula (7) (softening point 48 ° C., epoxy equivalent 263, binuclear content 72%)

[0028]

[Chemical 8]

Epoxy resin represented by the formula (8) (softening point 87 ° C., epoxy equivalent 335, binuclear content 7%)

[0030]

[Chemical 9]

Biphenyl type epoxy resin (Yuka-Shell Epoxy Co., Ltd., YX-4000HK, melting point 105 ° C.,
Epoxy equivalent 190)

Phenol novolac type phenol resin (melting point 81 ° C, marine product equivalent 105)

[0033]

[Table 1]

[0034]

The epoxy resin composition of the present invention has excellent fluidity, improved adhesion to various members such as semiconductor elements and lead frames, and low stress due to low elastic modulus at high temperature. The solder crack resistance of the semiconductor device at the time of mounting on a substrate at 260 ° C. is remarkably improved, and V-0 in UL-94 is maintained without using a bromine atom-containing organic compound or antimony compound. The values of ΣF and Fmax, which are the criteria for judgment, are also small, and the characteristic is that flame retardancy is superior.

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Claims (2)

[Claims] 1. An epoxy resin represented by the general formula (1) having (A) a binuclear content of 10 to 60%, (B) a phenol resin, (C) an inorganic filler and (D) a curing accelerator. An epoxy resin composition for semiconductor encapsulation, comprising: [Chemical 1] (In the formula, R represents hydrogen or an alkyl group having 1 to 4 carbon atoms, which may be the same or different from each other.
An integer of 3. n is an average value and is a positive number from 1 to 10) 2. A semiconductor device obtained by encapsulating a semiconductor element using the epoxy resin composition according to claim 1.