JPH0841293A - Epoxy resin composition for sealing and semiconductor device - Google Patents

Abstract

PURPOSE:To provide resin composition containing an epoxy resin, a curing agent, a curing promoter and an inorganic filler satisfying specified conditions, excellent in fluidity and moldability, useful for a semiconductor device excellent in moisture-resistant reliability and having a high filler content. CONSTITUTION:This resin composition contains (A) an epoxy resin, (B) a curing agent, (C) a curing promoter and (D) an inorganic filler (preferably containing one or more kinds of substances selected from amorphous silica, crystalline silica and alumina) so that the content of the inorganic filter may be >=75vol.% based on the whole composition in terms of true specific gravity. The volume fraction (phi) which is the ratio of this inorganic filter to an apparent volume of a molding produced by conducting compression molding at a pressure (P) under which the average particle size before compression molding is kept after compression molding is >=78% and the gradient (K) in an approximate expression representing a relation between the common logarithm of P and phi in P, i.e., phi=KlogP+alpha is 1 to 5, preferably 3 to 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encapsulating epoxy resin composition used for encapsulating electronic parts such as semiconductor elements and a semiconductor device using the same.

[0002]

2. Description of the Related Art Conventionally, an epoxy resin composition for encapsulation, which is used for protecting a semiconductor element, contains an epoxy resin, a curing agent, a curing accelerator and an inorganic powder filler as main components. In this case, the inorganic powder filler is used for the purpose of reducing the coefficient of thermal expansion of the molded body, improving the thermal conductivity, etc., but due to the recent increase in the degree of integration of integrated circuits and the increase in size of elements, the reliability is improved. It is desired to further improve the above characteristics while ensuring the above. To meet this requirement, the content of amorphous silica or the like, which has a small coefficient of thermal expansion, can be increased to reduce the coefficient of thermal expansion of the molded body, or the thermal conductivity of the crystal itself is high. It has become necessary to increase the content of silica powder, alumina powder, etc. to improve the thermal conductivity of the molded body. However, in this way, the content of the inorganic powder filler is increased, in the highly filled epoxy resin composition for encapsulation, the viscosity at the time of molding increases, the fluidity decreases, the moldability is impaired, As a result, a problem that reliability such as humidity resistance reliability of the semiconductor device is deteriorated is likely to occur. On the other hand, the conventional problem of burrs occurring when molding the encapsulating epoxy resin composition still remains.

Therefore, it is necessary to develop a technique in which the viscosity of the epoxy resin composition at the time of molding does not increase even if the content of the inorganic powder filler is increased. As a countermeasure for this, a method of improving the characteristics of the inorganic powder filler and a method of using a resin component having a low viscosity can be considered.

As a technique for improving the characteristics of the inorganic powder filler, hitherto, a spherical filler has been used or a filler such as Fuller or Andreasen which gives a close packed state in a continuous particle size distribution. Based on the empirical formula, there are those that focus on the parameters of the particle size distribution function to widen the width of the particle size distribution, or focus on the compactness of the inorganic powder filler and use a filler with a large compaction volume fraction. (Specifically, JP-A-5-170967), the effect as expected from the theory has not been obtained, the content of the inorganic powder filler is still high, and the fluidity and moldability are good. At present, no epoxy resin composition that can be retained has been obtained.

Based on the above theory, a considerable amount of ultrafine particles of 0.1 μm or less must be used in order to obtain a highly-fillable inorganic powder filler. However, ultrafine particles generally have a very strong cohesive property, and often exist as a considerable aggregate when used. Due to the influence of these agglomerates, the improvement of the filling property of the inorganic powder filler is not obtained as expected, and the narrow part filling property and moldability in the mold at the time of transfer molding of the epoxy resin composition are not improved. There is also the problem of being damaged. On the other hand, as for the burr characteristics, methods such as improving the thixotropy of the composition by adding fine particles have been attempted, but a decrease in fluidity also occurs, and the inorganic powder filler is highly filled, Moreover, a composition having good burr characteristics and fluidity has not been obtained.

[0006]

In view of the above circumstances, the problem to be solved by the present invention is to provide a highly-filled epoxy resin composition for encapsulation in which the content of the inorganic powder filler is increased during molding. It is to solve the problem that the viscosity increases, the fluidity decreases, and the moldability is impaired. That is, the present invention has a high content of the inorganic powder filler, and,
An object of the present invention is to provide an epoxy resin composition for encapsulation, which has excellent fluidity and moldability. Further, another object of the present invention is to provide a semiconductor device in which moisture resistance reliability is ensured by using the highly filled epoxy resin composition for encapsulation and the performance is improved by the high filling.

[0007]

The epoxy resin composition for encapsulation according to claim 1 of the present invention is an epoxy resin, a curing agent,
In a sealing epoxy resin composition containing a curing accelerator and an inorganic powder filler, as the inorganic powder filler, the average particle size of the inorganic powder filler before compression molding is maintained at a pressure (P ), The volume fraction (φ) of the inorganic powder filler in the apparent volume of the molded body obtained by compression molding the inorganic powder filler is 78% or more, and the inorganic powder filler before compression molding The gradient (K) of the following formula that approximates the relationship between the common logarithm of the pressure (P) whose average particle size is retained even after compression molding and the volume fraction (φ) at that pressure (P) is 1 to 5
The inorganic powder filler is contained in an amount of 75% by volume or more in terms of true specific gravity with respect to the entire encapsulating epoxy resin composition.

Φ = KlogP + α −−−−−− (α in the formula represents a constant.) The epoxy resin composition for encapsulation according to claim 2 of the present invention,
The epoxy resin composition for encapsulation according to claim 1, wherein the inorganic powder filler is an inorganic powder filler having a gradient (K) of the formula of 3 to 5.

The epoxy resin composition for encapsulation according to claim 3 of the present invention is the epoxy resin composition for encapsulation according to claim 1 or 2, wherein the inorganic powder filler is amorphous silica or crystal. It is characterized by containing an inorganic powder of at least one material selected from the group consisting of silica and alumina.

An encapsulating epoxy resin composition according to claim 4 of the present invention is the encapsulating epoxy resin composition according to claim 1, claim 2 or claim 3, in which only an epoxy resin and a curing agent are blended. The viscosity of the resin component at 150 ° C. is 3 poise or less.

A semiconductor device according to a fifth aspect of the present invention is a semiconductor device mounted on a lead frame using the epoxy resin composition for sealing according to the first, second, third or fourth aspect. The feature is that the element is sealed.

The present invention will be described in detail below. Regarding the compression molding of the inorganic powder filler in the present invention, only the inorganic powder filler is compression molded, and the pressure (P) is such that the average particle diameter of the inorganic powder filler before compression molding is also after the compression molding. This is the pressure that is maintained. If the pressure is too high,
The particles of the inorganic powder filler are destroyed, the average particle size of the inorganic powder filler after compression molding does not hold the average particle size before compression molding, and the inorganic powder filler in the molded product obtained by compression molding is Slurry (molten state of epoxy resin composition)
The state is different from that of the inorganic powder filler contained therein.
And, when the pressure at the time of compression molding is extremely high, the particles are broken, and the obtained molded body does not contain voids, that is, the volume of the inorganic powder filler in the apparent volume of the molded body. The fraction (φ) becomes asymptotic to 100%. Therefore, in the present invention, the pressure (P) during compression molding is such that the inorganic powder filler is present in the molded body obtained by compression molding in the same state as the inorganic powder filler contained in the slurry. The average particle diameter of the previous inorganic powder filler is limited to the range of pressure that can be maintained even after compression molding.

Next, the volume fraction (φ) of the inorganic powder filler in the apparent volume of the molded product obtained by compression molding the inorganic powder filler in the present invention will be described. The true specific gravity of each of n kinds of inorganic powders (n is an integer of 1 or more) used as the inorganic powder filler is d _i , and the blending weight of each inorganic powder is W _i (i is an integer from 1 to n). The true specific gravity d of the whole inorganic powder filler in the case of) is a value calculated by the following formula (A).

D = ΣW _i / Σ (W _i / d _i )-(A) Then, the volume fraction φ (%) of the inorganic powder filler in the apparent volume of the compact obtained by compression molding. Is calculated by the following formula (B), where W (g) is the weight of the inorganic powder filler and V (cc) is the apparent volume of the molded body obtained by compressing the inorganic powder filler.

Φ = 100 (W / d) / V --- (B) And, the average particle diameter of the inorganic powder filler before compression molding is less than the maximum pressure (Pmax) that is retained even after compression molding. The volume fraction φ of the inorganic powder filler of the molded body is always smaller than the volume fraction (φmax) of the inorganic powder filler of the molded body when molded at the maximum pressure (Pmax).

In the present invention, it is important that the volume fraction φ (%) of the inorganic powder filler in the apparent volume of the molded body, which is obtained by using the above calculation formula (B), is 78% or more. . This is because when an inorganic powder filler having φ of less than 78% is used, the melt viscosity of the epoxy resin composition having a high content of the inorganic powder filler is increased, which causes a problem in fluidity.

Further, the relationship between the common logarithm of the pressure (P) at which the average particle diameter of the inorganic powder filler before compression molding is maintained even after compression molding and the volume fraction (φ) at that pressure (P) is shown. Upon investigation, it was found that a good linear relationship was obtained. An approximate expression showing this linear relationship is shown by the above expression, and in the present invention, it is important that the gradient (K) of this expression is 1 to 5. This is because when the gradient (K) exceeds 5, the melt viscosity of the epoxy resin composition having a high content of the inorganic powder filler increases, which causes a problem in fluidity, and when the gradient (K) is less than 1. This is because it is practically difficult to obtain the inorganic powder filler. The more preferable range of the gradient (K) in this equation is 3-5.
Is. When the gradient (K) is less than 3, an epoxy resin composition having good fluidity and moldability can be obtained.
A new problem arises in that when molding the epoxy resin composition, burrs generated in the mold increase. The pressure range for obtaining the equation is preferably as wide as possible, but specifically, it may be obtained in the pressure range of about 60 to 300 kgf / cm ² .

The present invention is intended to solve the problems in the highly filled epoxy resin composition, and the highly filled epoxy resin composition is specifically an inorganic powder filling. The material contains 75% by volume or more of the total epoxy resin composition in terms of true specific gravity. This is because if it is less than 75% by volume, the effect of high filling such as low thermal expansion coefficient and high thermal conductivity of the obtained molded article cannot be sufficiently obtained.

The material of the inorganic powder filler used in the present invention is not particularly limited, but amorphous silica, crystalline silica,
Alumina, silicon nitride, aluminum nitride, boron nitride and the like can be exemplified. In order to reduce the coefficient of thermal expansion of the molded product of the epoxy resin composition, it is desirable to use amorphous silica, and to improve the thermal conductivity, it is desirable to use crystalline silica or alumina. In order to sufficiently attain high thermal conductivity, it is desirable that crystalline silica or alumina is contained in an amount of 50% by volume or more based on the whole inorganic powder filler.

The epoxy resin used in the present invention is not particularly limited, but one having a low viscosity at 150 ° C. is preferable. For example, a biphenyl skeleton, a naphthalene skeleton or a pt-butylbenzene skeleton is added to the basic skeleton of the resin. The bifunctional type or trifunctional type epoxy resin which has can be used.

The curing agent used in the present invention is not particularly limited, and a phenol type curing agent, an amine type curing agent, an acid anhydride type curing agent or the like can be used, but an epoxy resin having a low moisture absorption rate and high reliability. In order to form a composition, it is desirable to use a phenolic curing agent containing two or more phenolic hydroxyl groups in the molecule and having a low viscosity at 150 ° C. In order to maintain low melt viscosity and fluidity of the epoxy resin composition of the present invention having a high content of the inorganic powder filler of 75 vol% or more in terms of true specific gravity, only the epoxy resin and the curing agent are required. It is desirable that the viscosity of the blended resin component at 150 ° C. be 3 poises or less.

Examples of the curing accelerator used in the epoxy resin composition of the present invention include triphenylphosphine and its derivatives, imidazole and its derivatives, and the like. In addition to the above components, a releasing agent, a flame retardant, a pigment, a coupling agent, etc. may be added to the epoxy resin composition of the present invention, if necessary. Then, in the case of adding the coupling agent, it is also possible to use the one in which only the inorganic filler is surface-treated in advance with the coupling agent.

The semiconductor device of the present invention is obtained by encapsulating a semiconductor element mounted on a lead frame using the encapsulating epoxy resin composition according to claim 1, claim 2, claim 3 or claim 4. Since the content of the inorganic powder filler is as high as 75% by volume or more in terms of true specific gravity and the epoxy resin composition for sealing having good fluidity is used, voids are formed in the molded body. A semiconductor device that is hard to generate and has high moisture resistance reliability.

[0024]

[Function] The dense packing state of the inorganic powder filler in the molded body obtained by compression molding of the inorganic powder filler is the filling state of the inorganic powder filler in the encapsulating epoxy resin composition in a fluid state. Is close to. Therefore, the fact that the volume fraction (φ) of the inorganic powder filler in the molded product is large serves to increase the content of the inorganic powder filler in the encapsulating epoxy resin composition.

The fact that the volume fraction (φ) of the inorganic powder filler in the molded product is large means that there are few voids remaining between the particles of the inorganic powder filler in the molded product. Considering a composite material in which the void portion is filled with a liquid component, when the volume of the liquid component is equal to or smaller than the volume of the void portion, the deformation of the entire composite material is hindered by the contact between particles, and the fluid does not flow at all. While, on the other hand,
When the volume of the liquid component is larger than the volume of the void portion, the particles are separated by the liquid component, so that the particles can move freely to some extent, and the composite as a whole can be deformed, that is, in a flowable state. Becomes Therefore, in the encapsulating epoxy resin composition having the same content of the inorganic powder filler, the use of the inorganic powder filler having a large φ improves the fluidity of the encapsulating epoxy resin composition and improves the fluidity. Acts to lower the viscosity of. Therefore, φ is 78%
The encapsulating epoxy resin composition containing 75% by volume or more of the above inorganic powder filler in terms of true specific gravity is highly filled,
At the same time, the fluidity is also kept good.

The influence of the pressure (P) at the time of compression molding on the volume fraction (φ) of the inorganic powder filler in the molded body of the inorganic powder filler is expressed by the above-mentioned approximate expression. The fact that the gradient (K) of this approximate expression is small means that the increase of φ is small even if the pressure applied to the inorganic powder filler is increased. This means that when the pressure is applied to the inorganic powder filler, the process of compression molding from the state in which the average particle size of the inorganic powder filler before compression molding is maintained to the maximum pressure (Pmax) that is maintained even after compression molding. , Pmax requires a small amount of work to reach the volume fraction (φmax). On the contrary, the fact that the gradient (K) of the approximate expression is large means that a large amount of work is required to reach the volume fraction (φmax) at Pmax. In another way, the inorganic powder filler with a small gradient (K) in the approximate expression is easily deformed inside the powder layer with a small amount of work to be in a highly packed state, and the gradient (K) is large. With a small amount of work, the inorganic powder filler is less likely to be deformed inside the powder layer and is unlikely to be in a highly filled state. Examples of the inorganic powder filler having a large gradient (K) include agglomerated particles which have a strong inter-particle adhesive force and require a large amount of work to disintegrate.

In order to prepare a slurry of the epoxy resin composition, it is necessary to mix the inorganic powder filler and the liquid component and disperse the inorganic powder filler, and the conditions other than the characteristics of the inorganic powder filler are the same. Then, the amount of work received by the inorganic powder filler during the slurry preparation process is about the same. If the amount of work received by the inorganic powder filler is about the same, the inorganic powder filler having a small K is more likely to be in a highly filled state and the viscosity of the slurry is lower than that of a filler having a large K. As a result, the flowability of the inorganic powder filler having a small K is improved and the thixotropy is lowered. On the other hand, in the case of the inorganic powder filler having a large K, aggregated particles remain and the filling property is low. As a result, the flowability of the inorganic powder filler having a large K is lowered and the thixotropy is also increased. From the above, in order to keep the fluidity of the epoxy resin composition good, it is important to use an inorganic powder filler having K of 5 or less.

On the other hand, considering the burr characteristics when molding the epoxy resin composition, the burr has a property of reducing when the thixotropy of the epoxy resin composition is high. Therefore, it is necessary to impart a certain degree of thixotropy to the composition in order to maintain good burr characteristics. Since the thixotropy of the epoxy resin composition decreases as the inorganic powder filler having a smaller approximate expression gradient (K), the variability is improved by using an inorganic powder filler having an expression gradient (K) of 3 to 5. The characteristics are also maintained well.

Incorporation of amorphous silica into the inorganic powder filler serves to lower the coefficient of thermal expansion of the epoxy resin composition molding, and crystalline silica or alumina is incorporated into the inorganic powder filler. Has the function of increasing the thermal conductivity of the molded body of the epoxy resin composition.

[0030]

EXAMPLES The present invention will be described below based on examples. Of course, the present invention is not limited to the examples below.

In each of the following examples and comparative examples, the epoxy resin is a bifunctional biphenyl type epoxy resin, manufactured by Yuka Shell Epoxy Co., Ltd., product number YX-4000H (epoxy equivalent 190, melting at 150 ° C.). Viscosity 0.2 poise, indicated as YX in Tables 4 and 5 below) or pt-
Butylbenzene type epoxy resin, Tohto Kasei Co., Ltd.
Product number ZX-1257 (epoxy equivalent 172,150
Melt viscosity at 0 ° C. is 0.04 poise, indicated as ZX in Table 4 below), and the curing agent is a naphthol-phenol polymer resin manufactured by Nippon Kayaku Co., Ltd., product number OCN-7000.
(Hydroxyl equivalent 172, melt viscosity at 150 ° C 8 poise)
Triphenylphosphine (hereinafter abbreviated as TPP) manufactured by Hokuko Kagaku Kogyo Co., Ltd. is used as a curing accelerator, natural carnauba wax is used as a releasing agent, and an epoxysilane-based coupling agent is used. As a coupling agent, product number A-187 manufactured by Nippon Unicar Co., Ltd. is used, and as a flame retardant, diantimony trioxide (product number Sb ₂ O ₃ -LS) manufactured by Mitsubishi Materials Co., Ltd. is used. As the material, carbon black (product number 750-B) manufactured by Mitsubishi Materials Corp. was used.

In each of the following Examples and Comparative Examples,
The inorganic powder shown in Table 1 below was used as the inorganic powder.

[0033]

[Table 1]

In the following examples and comparative examples, the inorganic powder was charged.
Compression molding of filler is 60 kgf / cm ², 120kgf /
cm², 180kgf / cm², 240kgf / c
m², 300 kgf / cm²And single-axis application by changing the pressure level
This was carried out by pressure to obtain a cylindrical molded body. Pressure is 300
kgf / cm²Powder obtained by crushing the molded product at
As a result of measuring the average particle size of
Since it was the same as the diameter measurement result, particles up to this pressure
It can be said that no destruction has occurred. The following examples and
In the comparative example and the inorganic powder filling in the apparent volume of the compact,
The volume fraction (φ) of the filler is calculated from the diameter and thickness of the molded body
Apparent volume V and weight W of molded product and inorganic powder filling
It is a value calculated by the above-mentioned formula (B) from the true specific gravity d of the material.
And in the following, the pressure is 300 kgf / cm.²Measured with
Φ to φ₃₀₀Is written.

The relationship between the common logarithm of the pressure (P) at which the average particle diameter of the inorganic powder filler before compression molding is maintained even after compression molding and the volume fraction (φ) at that pressure (P) is shown. The gradient (K) of the approximate expression is 60 kgf / cm ² , 120 k
gf / cm ² , 180 kgf / cm ² , 240 kgf /
Each φ measured at each pressure (P) of cm ² and 300 kgf / cm ² is plotted on the diagram with the horizontal axis being the common logarithm of P and the vertical axis being φ, and the slope of the straight line is calculated by the least square method. I asked. As a representative example of the figure in which the gradient (K) is obtained, FIG.
The figure which calculated | required the gradient (K) in Example 1 is shown in FIG. In FIG. 1, the plotted points of the measured data and the straight line calculated by the least square method using these data are shown.
The slope of this straight line is K.

(Examples 1 to 8 and Comparative Examples 1 to 7) Silica powders S1, S2, S3, S4 and alumina powder A1 shown in Table 1 were mixed at the compounding amounts shown in Tables 2 and 3. The obtained mixed powder (inorganic powder filler) was compression-molded, φ ₃₀₀ and the gradient (K) were measured, and the obtained results are shown in Tables 2 and 3.

Next, the coupling agent was sprayed and mixed with the mixed powders having the blending amounts shown in Tables 4 and 5 (those not subjected to compression molding) by the treatment amounts shown in Tables 4 and 5, and mixed. The powder was surface-treated. Next, the surface-treated mixed powder,
The epoxy resin, the curing agent, the curing accelerator, the flame retardant, the release agent and the pigment were mixed in the amounts shown in Tables 4 and 5, and the resulting mixture was kneaded with a mixing roll at 90 ° C. for 6 minutes and then at room temperature. The mixture was cooled to 0 and pulverized to obtain an epoxy resin composition (molding material).

The performance evaluation of the obtained epoxy resin composition and its molded product and the performance evaluation of the semiconductor device produced by using each epoxy resin composition were carried out by the following method, and the evaluation results are shown in Tables 6 and 7. Indicated.

(Gel time of epoxy resin composition):
It was measured at 175 ° C. using a Curalastometer V type manufactured by Orientec Co., Ltd. (Melt viscosity of epoxy resin composition): Flow tester CFT500A type manufactured by Shimadzu Corporation was used, and temperature was 175.
° C, load 10 kgf, nozzle size 1 mm (diameter) x 1
The minimum melt viscosity was determined at 0 mm. (Spiral flow of epoxy resin composition): EMMI
In compliance with the standard, using a spiral flow dedicated mold, 17
The flow length of the sample during transfer molding at 5 ° C was measured. (Burr characteristics of epoxy resin composition): Transfer molding was performed at 175 ° C. for 90 seconds with a dedicated mold for measuring variflow, and the flow length of the sample was measured at a slit having a thickness of 20 μm provided in the mold.

(Coefficient of thermal expansion of molded body): Transfer molding was performed at 175 ° C. for 90 seconds using a dedicated mold for producing JIS test pieces, and after-curing was performed at 175 ° C. for 6 hours to prepare a test piece. did. About this test piece, using a TMA device (manufactured by Rigaku Denki Co., Ltd.), under a compressive load of 1 g, at a temperature rising rate of 5 ° C./min, at 50 to 100 ° C.
The coefficient of thermal expansion (α ₁ ) in the temperature range was measured. (Thermal conductivity of the molded body): Transfer molding was performed at 175 ° C. for 90 seconds with a dedicated mold, and after-curing was performed at 175 ° C. for 6 hours to prepare a test piece for measuring thermal conductivity. This test piece was measured using a non-stationary probe method QTM-D3 (manufactured by Kyoto Electronics Manufacturing Co., Ltd.). (Moldability of molded product): The moldability was evaluated by the number of voids in the evaluation package. The evaluation package was produced by transfer molding of the epoxy resin composition using a dedicated mold capable of obtaining a 26SOP package having outer dimensions of 8.9 × 17.4 × 2.7 mm. The molding conditions were a temperature of 175 ° C., an injection time of 12 seconds, a pressurization time of 90 seconds, and an injection pressure of 70 kgf / cm ² . The number of voids in the package was observed from both front and back sides of the evaluation package with an ultrasonic probe (manufactured by Canon Inc., M-700II) and used as the number of void images with a diameter of 1 mm or more in the obtained chart. . (Moisture resistance reliability of semiconductor device): External dimensions 8.9 × 17.
For evaluation, TEG (test semiconductor device) with 3 μm aluminum wiring attached to the lead frame is molded by transfer molding using a dedicated mold that can obtain a 4 × 2.7 mm 26SOP package. A 26SOP package was obtained. The molding conditions are a temperature of 175 ° C., an injection time of 12 seconds, a pressurization time of 90 seconds, and an injection pressure of 70 kgf /.
cm ² and then after-cured at 175 ° C. for 6 hours to obtain an evaluation package. The obtained 26 for evaluation
The SOP package was left under the conditions of 130 ° C., 85%, and 30 V, and the elapsed time until a defect occurred in the aluminum wiring of the TEG was examined to evaluate the moisture resistance reliability.

[0041]

[Table 2]

[0042]

[Table 3]

[0043]

[Table 4]

[0044]

[Table 5]

[0045]

[Table 6]

[0046]

[Table 7]

As is clear from Tables 6 and 7 showing the evaluation results, in the epoxy resin compositions of the examples of the present invention, the content of the inorganic powder filler is as high as 75% by volume or more in terms of true specific gravity,
Moreover, it was confirmed that the fluidity (melt viscosity and spiral flow) was good, and as a result, the moldability of the obtained molded product was good, and the moisture resistance reliability of the obtained semiconductor device was also good. Was done. Further, as is clear from the comparison between Example 1 and Example 2, Example 2 in which the value of K is 3.1 is
In addition to the above effects, it was confirmed that the variflow was also improved. Further, as is clear from the comparison between Example 3 and Comparative Example 3, in Comparative Example 3 in which the content of the inorganic powder filler is less than 75% by volume in terms of true specific gravity, the amorphous silica powder of the same type as Example 3 is used. It can be seen that even when the above is used as the filler, it is inferior in terms of thermal expansion coefficient and thermal conductivity because of its low content rate. Further, the inclusion of amorphous silica in the inorganic powder filler serves to lower the coefficient of thermal expansion of the molded body of the epoxy resin composition, and the inclusion of crystalline silica or alumina in the inorganic powder filler results in epoxy resin. It was also confirmed from the results of Tables 6 and 7 that the molded body of the resin composition also has a function of increasing the thermal conductivity.

[0048]

According to the epoxy resin composition for encapsulation according to claims 1 to 3 of the present invention, the content of the inorganic powder filler is as high as 75% by volume or more and the fluidity is good. An epoxy resin composition is obtained. Therefore, by using the encapsulating epoxy resin composition of the present invention, it is possible to obtain a molded body with few voids (having good moldability), so that the moisture resistance reliability is ensured and the performance is improved by the high filling. It is possible to obtain a semiconductor device that has been damaged.

According to the encapsulating epoxy resin composition of the fourth aspect of the present invention, it is possible to obtain an encapsulating epoxy resin composition having improved variflow in addition to the above effects.

Further, according to the semiconductor device of the fifth aspect of the present invention, it is possible to obtain a semiconductor device in which the moisture resistance reliability is ensured and the performance is improved by the high filling.

[Brief description of drawings]

FIG. 1 is a graph of an inorganic powder filler of Example 1,
6 is a graph showing the relationship between the common logarithm of pressure (P) and the filler volume fraction (φ) in the apparent volume of a molded body obtained by compression molding an inorganic powder filler at the pressure (P).

Claims (5)

[Claims] 1. An epoxy resin composition for encapsulation comprising an epoxy resin, a curing agent, a curing accelerator and an inorganic powder filler, wherein the inorganic powder filler is an average particle size of the inorganic powder filler before compression molding. Is a pressure (P) held even after compression molding, and the volume fraction (φ) of the inorganic powder filler in the apparent volume of the molded product obtained by compression molding the inorganic powder filler is 78% or more, Moreover, the average particle size of the inorganic powder filler before compression molding approximates the relationship between the common logarithm of the pressure (P) retained even after compression molding and the volume fraction (φ) at the pressure (P) below. The slope (K) of the formula is 1-5
The epoxy resin composition for encapsulation containing 75% by volume or more of the inorganic powder filler, which is calculated as true specific gravity, with respect to the entire epoxy resin composition for encapsulation. φ = KlogP + α −−−−−− (α in the formula represents a constant.) 2. The epoxy resin composition for encapsulation according to claim 1, wherein the inorganic powder filler is an inorganic powder filler having a gradient (K) of the formula of 3 to 5. 3. The inorganic powder filler is at least one selected from the group consisting of amorphous silica, crystalline silica and alumina.
The epoxy resin composition for encapsulation according to claim 1 or 2, which contains inorganic powders of various kinds of materials. 4. The epoxy resin for encapsulation according to claim 1, 2 or 3, wherein the viscosity of the resin component containing only the epoxy resin and the curing agent at 150 ° C. is 3 poise or less. Composition. 5. A semiconductor element mounted on a lead frame is encapsulated using the epoxy resin composition for encapsulation according to claim 1, claim 2, claim 3 or claim 4. Semiconductor device.