JPH1160914A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having three characteristics of high liquidity, low hygroscopicity, and good moldability by including an epoxy resin and a hardening (accelerating) agent and a filler so as to satisfy a specific requirement. SOLUTION: This composition is obtained by compounding (A) an epoxy resin, (B) a hardener, (C) a hardening accelerator and (D) a filler under a condition regulated so that, when an initial viscosity at (t)=0 sec (an extrapolated value) is represented by η0, and the slope of a nearly linear part B of a viscosity logarithm curve A, which is formed by measuring the viscosity of the composition from just after the preparation of the composition, and plotting the logarithm viscosity of the composition versus the measuring time (t), is represented by Cs, η0 may be 100-3,000 poise, preferably 100-1,500 poise, Cs may be <=0.1, preferably <=0.04, and the content of the component D in the whole volume of the molded composition may be 70-88 vol.%, preferably 73-88 vol.% expressed in terms of true specific gravity.

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 used for sealing a semiconductor element and the like, and a semiconductor device in which a semiconductor element is sealed with the epoxy resin composition. The present invention relates to an epoxy resin composition having three characteristics of high fluidity, low moisture absorption, and good moldability, and a semiconductor device excellent in moisture resistance reliability and moisture reflow resistance.

[0002]

2. Description of the Related Art Conventionally, a sealing material for sealing and protecting a semiconductor element (chip) has been formed by molding an epoxy resin composition by transfer molding or the like.
The epoxy resin composition for encapsulating a semiconductor device contains an epoxy compound (resin), a filler of inorganic powder and a curing agent as main components. It is used for the purpose of reducing the moisture absorption and improving the thermal conductivity.

On the other hand, in recent years, the functions of integrated circuits have been concentrated.
In addition, since the degree of integration has become indispensable, semiconductor devices (packages) have been made larger and thinner. However, semiconductor devices are not damaged by the effects of the larger and thinner semiconductor devices. As described above, it is further desired to reduce the thermal expansion coefficient and the moisture absorption rate of the sealing material, which is a molded article of the epoxy resin composition, and to improve the thermal conductivity. Therefore, high filling is performed by increasing the content of the filler in the epoxy resin composition.

[0004]

However, when the filler content of the epoxy resin composition is increased to increase the filler content, the viscosity of the epoxy resin composition increases, the fluidity decreases, and the epoxy resin composition decreases. The stress at the time of the flow of the object increases, which causes the lead frame and the die pad to move up and down, displacing the stage, and causing wire sweep such as disconnection and deformation of the wire. Also, when an epoxy resin composition having a high filler content is formed by transfer molding, the epoxy resin composition is not filled in a narrow portion or a thin portion in the mold, so that a cavity is formed in the sealing material, A problem that voids are formed on the surface or inside of the stopper material and the formability is reduced, and aluminum wiring is corroded by moisture that is aggregated and unevenly distributed in these cavities and voids, thereby impairing the moisture resistance reliability of the semiconductor device. was there.

In order to reduce voids in the sealing material,
A method of reducing the volatile content of the epoxy resin composition in the tablet or reducing the entrainment of air during molding (for example, JP-A-64-61028, JP-A-1-129)
No. 424) has been studied, but these methods cannot sufficiently reduce the voids. In particular, the voids on the surface of the sealing material of a thin or large semiconductor device have not been completely eliminated. There has been a demand for a more effective void reduction measure.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is difficult to generate a stage displacement, a wire sweep, a cavity or a void in a lead frame or a die pad portion, and has a low thermal expansion coefficient and a low moisture absorption rate. It is an object of the present invention to provide an epoxy resin composition capable of forming a sealing material having a high rate. Another object of the present invention is to provide a semiconductor device having high humidity resistance and high reflow resistance.

[0007]

According to the first aspect of the present invention, there is provided an epoxy resin composition comprising an epoxy resin, a curing agent, a curing accelerator and a filler, wherein the shear rate is 5 ( The logarithm of the viscosity with respect to the measurement time is plotted under the condition of 1 / sec) to form a logarithmic logarithmic line A. The viscosity at the measurement time of 0 second is η0, and the slope of the substantially linear portion B of the logarithmic logarithm A is Cs. When η0 is 100 to 3000 poise and Cs is 0.1 or less, the content of the filler relative to the total volume of the epoxy resin composition molded product is 70 to 70 in terms of true specific gravity.
It is characterized by containing a filler so as to be 88% by volume.

The epoxy resin composition according to the second aspect of the present invention has, in addition to the constitution of the first aspect, an η0 of 100 to 100.
1500 poise, Cs is 0.04 or less, and the filler is contained such that the content of the filler with respect to the total volume of the epoxy resin composition molded article is 73 to 88% by volume in terms of true specific gravity. It is assumed that. The epoxy resin composition according to claim 3 of the present invention is obtained by compressing and molding the filler at a pressure at which the average particle diameter of the powder constituting the filler is maintained, in addition to the constitution of claim 1 or 2. It is characterized by forming a filler compact and using a filler such that the net volume percentage of the powder of the filler in the apparent volume of the filler compact is 83% or more.

The epoxy resin composition according to claim 4 of the present invention has, in addition to any one of the constitutions of claims 1 to 3, a viscosity at 150 ° C. of the resin component of the epoxy resin and the curing agent of 2 poise or less. It is characterized by being. Further, the epoxy resin composition invention according to claim 5 of the present invention provides, in addition to any one of claims 1 to 4,
It is characterized by using at least one selected from diazabicycloundecene, diazabicyclononane and imidazole compounds as a curing accelerator.

The epoxy resin composition according to claim 6 of the present invention further comprises, in addition to any one of the constitutions of claims 1 to 5, a fatty acid or a fatty acid derivative having 26 or less carbon atoms relative to the total weight. 0.05 to 5% by weight. A semiconductor device according to a seventh aspect of the present invention is characterized in that a semiconductor element is sealed by transfer molding with the epoxy resin composition of the first to sixth aspects.

[0011]

Embodiments of the present invention will be described below. As the epoxy resin, any one such as a bifunctional biphenyl type epoxy resin or a trifunctional dicyclopentadiene type epoxy resin can be used, and as the curing agent, any one such as a phenol aralkyl type curing agent or a phenol novolak type curing agent can be used. be able to. It is preferable that the epoxy resin and the curing agent have a ratio of epoxy equivalent / phenol equivalent of 0.9 to 1.1 based on the weight of the resin component. Further, it is preferable to set the type of the epoxy resin and the curing agent and the mixing ratio thereof so that the mixture of the epoxy resin and the resin component of the curing agent has a viscosity of 2 poise or less at 150 ° C. (claim 4). When the viscosity of the mixture of the epoxy resin and the resin component of the curing agent at 150 ° C. exceeds 2 poise, η0 increases to exceed 3000, which may cause a decrease in moldability such as generation of voids. The lower limit is set to 0, since the smaller the viscosity, the better.

As the curing accelerator, any one can be used as long as it lowers Cs and maintains the stability of viscosity. Diazabicycloundecene (DBU), diazabicyclononane (DB
It is preferable to use at least one selected from N) and imidazole compounds (claim 5). The curing accelerator is preferably added in such an amount that the gel time of the epoxy resin composition becomes 20 to 40 seconds. Any filler can be used as the filler as long as it is an inorganic powder, but the amount of the filler is 8 to the total amount of the epoxy resin composition.
It is preferably set to 1 to 93% by weight. In order to reduce the coefficient of thermal expansion and the rate of moisture absorption of the sealing material, it is preferable to increase the blending ratio of the amorphous silica powder having a low coefficient of thermal expansion of itself, and the thermal conductivity of the sealing material. In order to increase the ratio, it is preferable to increase the compounding ratio of crystalline silica powder or alumina powder having a high thermal conductivity.

In the present invention, as the filler, the average particle size of the powder before compression molding is a filler occupying the apparent volume of the filler molded body obtained by compression molding the filler at a pressure that is maintained after compression molding. A powder having a net volume percentage Φ of 83% or more is used (claim 3). The true specific gravity of each of n kinds of powders (n is an integer of 1 or more) constituting the filler is d _i , and the compounding weight of each powder is W _i (i is 1).
整数 n), the true specific gravity d of the entire filler is a value calculated by the following equation (a). When the filler powder is amorphous silica powder, its true specific gravity is generally 2.21 in a state where there are no defects such as voids in the powder,
There may be defects in the powder, and in this case, the true specific gravity of the amorphous silica powder may be less than 2.21.

D = ΣW _i / Σ (W _i / d _i ) (a) Then, the net volume percentage Φ of the powder in the filler compact obtained by compression molding is obtained by dividing the weight of the filler to be compressed by W
(G) Assuming that the apparent volume of the filler molding is V (cc), it is a value calculated from the following equation (b). Φ = W / (d × V) × 100 (b) In forming the above-mentioned filler molding, the pressure at the time of compression molding of the filler is determined by the average particle diameter of the filler powder before compression molding. It is important that the pressure be maintained after compression molding. If this pressure is too high, the powder will be broken and the average particle size of the powder after compression molding will be different from the average particle size of the powder before compression molding, and the net volume percentage Φ determined by equation (b) will be The value may not reflect the actual property of the filler in the stopper. This is because any filler powder is destroyed when the pressure during compression molding is extremely increased, and the filler compact approaches a state in which no void is included, and the net volume percentage Φ approaches 100% by volume. It is because you will be. Therefore, the net volume percentage is set so that the powder of the filler contained in the actual sealing material and the powder of the filler present in the filler molding have the same state (the same average particle size). The compression molding of the filler at the time of obtaining Φ is performed at a pressure at which the average particle size of the powder of the filler before the compression molding is maintained even after the compression molding.

A filler compact is formed at a maximum pressure within a range in which the average particle size of the filler powder before the compression molding is maintained even after the compression molding, and the apparent volume and compression of the filler compact are determined. From the weight of the filler to be filled, the net volume percentage is a value equal to or greater than the net volume percentage obtained from the filler molded article molded at a pressure lower than the maximum pressure. The upper limit of the net volume percentage Φ is 93% in view of the true specific gravity of the available filler.

The epoxy resin composition of the present invention is prepared by mixing the above epoxy resin, a curing agent, a curing accelerator and a filler. Then, the viscosity of the epoxy resin composition was measured immediately after preparation using a cone-plate rotational viscometer at a shear rate of 5 (1 / second) and a temperature of 175 ° C.,
As shown in FIG. 1, the logarithm of the viscosity of the epoxy resin composition (common logarithm) with respect to the measurement time t is plotted to form a viscosity logarithmic line A, and the initial viscosity at the measurement time t = 0 seconds (extrapolated value). ) Is η0, and the slope (stability) of the substantially linear portion B of the viscosity logarithmic line A is Cs, η0 is 100 to 3000 poise,
The types and blending amounts of the epoxy resin, the curing agent, the curing accelerator, and the filler, and the net volume percentage Φ of the filler are set so that Cs is 0.1 or less (Claim 1).
In general, for a composition having a gel time of about 30 seconds, the viscosity logarithmic line A shows a substantially linear behavior during the measurement time of 0 to 15 seconds (the substantially linear portion B shows the measurement time of 0 to 15 seconds). Formed between them). Therefore, also in the present invention, the interval between the measurement times 0 to 15 seconds is regarded as the substantially linear portion B of the logarithmic logarithmic line A, and the slope Cs between them is determined. When the gel time is shorter than 30 seconds, the substantially straight portion B is shorter than the measurement time of 0 to 15 seconds, and when the gel time is longer than 30 seconds, the substantially straight portion B is longer than the measurement time of 0 to 15 seconds. Therefore, the time range for obtaining Cs is not limited to the measurement time of 0 to 15 seconds. Also C
s is a value exceeding 0 (Cs> 0).

In the present invention, the filler is made of an epoxy resin so that the content of the filler relative to the total volume of the epoxy resin composition molded article as the sealing material is 70 to 88% by volume in terms of the true specific gravity of the filler. It must be contained in the composition (claim 1). If the content of the filler in the sealing material is less than 70% by volume, there is a possibility that the effect of reducing the moisture absorption and the coefficient of expansion of the sealing material may not be sufficiently obtained. In addition, if the epoxy resin composition contains an amount of the filler that exceeds 88% by volume in the sealing material, the fluidity of the epoxy resin composition may be reduced.

The epoxy resin composition of the present invention has η0 of 100 to 3000 poise and Cs of 0.1 as described above.
As described below, the viscosity of the epoxy resin composition after being injected into the cavity of the mold can be kept low to prevent pressure loss at the time of holding under pressure, and voids ( Air bubbles) can be eliminated and reduced.

That is, pinholes and voids generated in the sealing material of the epoxy resin composition in which the filler is highly filled to 70% by volume or more when the epoxy resin composition is injected into the cavity through the gate of the mold. The amount of voids that occur and
Two factors greatly affect whether voids generated in the epoxy resin composition after injection into the cavity are easily lost. In the case of an epoxy resin composition highly filled with a filler, it is necessary to lower the viscosity of the resin component. As a result, voids frequently occur in the epoxy resin composition due to jetting flow or air entrapment during cavity injection. . Therefore, the epoxy resin composition of the present invention is reduced by eliminating voids (air bubbles) generated in the epoxy resin composition in the cavity by setting η0 to 100 to 3000 poise and Cs to 0.1 or less as described above. It was made possible.

The epoxy resin composition of the present invention contains a filler so that the content of the filler relative to the total volume of the sealing material is 70 to 88% by volume in terms of the true specific gravity of the filler. Therefore, the thermal expansion coefficient and the moisture absorption rate of the sealing material can be reduced, the thermal conductivity can be improved, and the moisture resistance reliability and moisture reflow resistance of the semiconductor device can be increased.

In the epoxy resin composition of the present invention, η0
In order to reduce this, it is conceivable to increase and improve the value of the above-mentioned net volume percentage Φ, to increase the free volume of the filler, or to lower the melt viscosity of the resin component of the epoxy resin or the curing agent. However, it is effective to add and mix an internal lubricating release agent or plasticizer. As such a release agent or a plasticizer, a fatty acid or fatty acid derivative having 10 to 26 carbon atoms can be used. 10 to 2 carbon atoms
When a fatty acid or a fatty acid derivative deviating from the range of 6 is used, the effect of reducing η0 is reduced. It is preferable that the fatty acid or the fatty acid derivative is contained in an amount of 0.05 to 5% by weight based on the total weight of the epoxy resin composition.
If the content of the fatty acid or the fatty acid derivative is less than 0.05% by weight, the effect of reducing η0 may be reduced. If the content of the fatty acid or the fatty acid derivative exceeds 5% by weight, the epoxy resin composition ( Alternatively, the adhesion between the lead frame and the sealing material may be impaired, or the sealing material may cause poor appearance due to dirt or the like.

When a large and thin semiconductor device is formed using the epoxy resin composition of the present invention, in order to further reduce the coefficient of thermal expansion and moisture absorption of the sealing material and to improve the thermal conductivity, Further increase the blending amount of the filler
It is necessary to further reduce 0 and Cs. So 20mm
When forming a large-sized semiconductor device having a corner or more, or when molding a thin semiconductor device having a thickness of 1.4 mm or less,
η0 is 100 to 1500 poise, Cs is 0.04 or less, and the filler is contained so that the content of the filler with respect to the whole volume of the epoxy resin composition molded article is 73 to 88% by volume in terms of true specific gravity. An epoxy resin composition is prepared (Claim 2). If η0 and Cs deviate from this range, voids may be formed on the surface and inside in a large semiconductor device, and in a thin semiconductor device, in addition to surface voids, defects such as wire sweep, stage displacement, and unfilling may occur. May occur.

The semiconductor device of the present invention can be formed by encapsulating a semiconductor element with the epoxy resin composition by transfer molding, and has high moisture resistance reliability and moisture reflow resistance.

[0024]

The present invention will be described below in detail with reference to examples.
Note that the present invention is not limited to this embodiment. (Examples 1 to 8 and Comparative Examples 1 to 3) As the epoxy resin, a bifunctional biphenyl type epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd., epoxy equivalent: 195, melt viscosity at 150 ° C. 0.1 poise, product number) YX-4000H) and a trifunctional dicyclopentadiene type epoxy resin (manufactured by Dainippon Ink and Chemicals, epoxy equivalent: 283, melt viscosity at 150 ° C .: 4 poise, product number: HP7200H). As the curing agent, a phenol aralkyl type curing agent (manufactured by Mitsui Toatsu Co., Ltd., hydroxyl equivalent 175, melt viscosity at 150 ° C. 3)
Poise, part number XL225-3L), and phenol novolak type curing agent (manufactured by Gunei Chemical Co., Ltd., hydroxyl equivalent: 10)
5, a melt viscosity at 150 ° C. of 7 poise) was used.

As the curing accelerator, diazabicycloundecene (manufactured by San Apro Co., Ltd.), diazabicyclononane (manufactured by San Apro Co., Ltd.), and triphenylphosphine (TPP, manufactured by Hokuko Chemical Co., Ltd.) Was used. Natural carnauba wax was used as the wax. As the lubricating fatty acid, stearic acid (manufactured by NOF Corporation, product number NAA-174, carbon number is C-18), and montanic acid (product number Wax-S, carbon number is C-28) were used. . As the coupling agent, an epoxysilane-based coupling agent (manufactured by Nippon Unicar Co., Ltd., product number A-187) was used.
(Manufactured by Mitsubishi Materials Corporation, part number Sb ₂ O ₃ -NT) diantimony trioxide as a flame retardant was used. Carbon black (manufactured by Mitsubishi Materials Corporation, product number 750-B) was used as the pigment.

As the filler, three types (S)
1, S2, and S3) were prepared by mixing the amorphous silica powders. S1 is an amorphous silica powder manufactured by Tokuyama Corporation (true specific gravity 2.2, average particle size 15 μm, specific surface area 0.8 m ² /
g) and S2 are amorphous silica powders manufactured by Tokuyama Corporation (true specific gravity 2.2, average particle diameter 8 μm, specific surface area 1.5 m ² /
g) and S3 are amorphous silica powder manufactured by Tokuyama Corporation (true specific gravity 2.2, average particle size 0.3 μm, specific surface area 15 m ² /
g).

The net volume percentage Φ of the filler is determined by forming a cylindrical filler compact by uniaxial pressing at a compression pressure of 100 MPa, and calculating the true specific gravity d and weight W of the compacted filler.
(G) and the apparent volume of the filler molded body were calculated by substituting V (cc) into the above equation (b). The average particle size of the powder of the filler after compression molding was measured by disintegrating the molded material of the filler. As a result, the average particle size of the powder of the filler before compression molding was the same. At 100 MPa, no destruction of the filler powder (amorphous silica powder) occurred. The particle size distribution of the filler powder is measured by a laser scattering particle size distribution meter (SK laser TRO-7000S manufactured by Seishin Enterprise).
And the ratio of powder having a size of 50 μm or more was determined from the weight accumulation curve at that time.

The above materials were mixed in the proportions shown in Tables 1 and 2 to prepare an epoxy resin composition. The physical properties of the epoxy resin composition and the physical properties of a semiconductor device formed using the epoxy resin composition were as follows. Was measured as follows. (Η0 and Cs) A rotary rheometer and a liquid meter (MR-300 type) manufactured by Rheology Co., Ltd. were used.
Using a cone plate having a cone angle of 5 degrees as a measuring jig, the viscosity was measured immediately after preparation of the epoxy resin composition at a shear rate of 5 (1 / sec) in a sine wave mode,
The initial viscosity (after 0 seconds of the measurement time) was defined as η0. Next, the horizontal axis is plotted with time, and the vertical axis is plotted with a logarithmic value of viscosity to draw a logarithmic logarithmic line A.
The inclination of the substantially straight line portion B was obtained and set as Cs.

(Gel Time) The gel time was measured at 175 ° C. using a Curastometer V type manufactured by Orientec Co., Ltd. (Melt viscosity) Flow tester CF manufactured by Shimadzu Corporation
Using a T500A type, the minimum melt viscosity was determined at 175 ° C., a load of 10 kgf, and a nozzle size of 1 mmφ × 10 mm.

(Spiral Flow) The flow length of the sample during transfer molding at 175 ° C. was measured using a mold dedicated to spiral flow in accordance with the EMMI standard. (Coefficient of thermal expansion) 1 in a special mold for manufacturing JIS test pieces
After transfer molding at 75 ° C. for 90 seconds, 17
After-curing was performed at 5 ° C. for 6 hours to form a test piece. This is called a TMA device (TAS100 system,
The thermal expansion coefficient was measured at a heating rate of 5 ° C./min under a compressive load of 1 g, and α ₁ in a temperature range of 50 to 100 ° C. was calculated using a compression load of 1 g.

(Formability) The formability was evaluated by forming a semiconductor device (package) for performance evaluation and measuring the amount of voids generated in the semiconductor device (package). The semiconductor device for performance evaluation is a 15 × 14 mm, 3.0 mm thick 60 QFP mold and a 28 mm square, 3.2 mm thick 160 QF.
Using a mold of P, the epoxy resin composition was transfer-molded to produce a molded article, and this molded article was formed by after-curing at 175 ° C. for 6 hours. Molding conditions are temperature 17
5 ° C., injection time 12 seconds, pressurization time 90 seconds, injection pressure 70
kg / cm ² . The voids inside the semiconductor device were observed from both front and back sides with an ultrasonic probe (M-700II manufactured by Canon Inc.), and the number of void images having a diameter of 1 mm or more was counted in the chart obtained thereby. . In addition, pinholes and unfilled portions on the surface are 0.1 m visually.
Those with mφ or more were counted as defective.

(Moisture resistance reliability) A molded product was formed by transfer molding using a TEG having aluminum wiring of 3 μm and using a mold for a 26SOP package. The molding conditions were a temperature of 175 ° C., an injection time of 12 seconds, and a pressurization time of 90.
Second, the injection pressure is 70 kg / cm ² . This molded product is
After-cured at 75 ° C for 6 hours, 26S for performance evaluation
An OP semiconductor device was obtained. The semiconductor device for performance evaluation was left under the conditions of 130 ° C., 85%, and 30 V, and 50%
The failure occurrence time (time until 50% of the aluminum wiring becomes a conduction failure) was measured.

(Moisture reflow resistance) A Cu frame on which a silicon chip is mounted is 15 × 14 mm and has a thickness of 3.0 m.
m for 60QFP, 28mm square and 3.2mm thick
An epoxy resin composition was transfer-molded using a 160 mm FP mold having a diameter of 160 mm to produce a molded product. The molding conditions were a temperature of 175 ° C, an injection time of 12 seconds, a pressurization time of 90 seconds,
The injection pressure was 70 kg / cm ² . 175
After-curing at 6 ° C. for 6 hours, four semiconductor devices for performance evaluation were formed. 85 semiconductor devices for this performance evaluation
After leaving for 168 hours under the conditions of 85 ° C. and 260 ° C.
For 10 seconds. Thereafter, the number of semiconductor devices in which the sealing material of the epoxy resin composition was separated from the chip, the frame, and the die pad portion and the number of cracks in the sealing material of the epoxy resin composition were evaluated.

Tables 1 and 2 show the results of the above tests.

[0035]

[Table 1]

[0036]

[Table 2]

As is clear from Tables 1 and 2, the melt viscosity of Examples 1 to 8 can be lower than that of Comparative Examples 2 and 3, and the fluidity (spiral flow) can be higher than that of Comparative Examples 1 to 3. Could be higher. Moreover, Examples 1 to 8
The sealing material formed by molding and curing was able to have a lower coefficient of thermal expansion and a lower moisture absorption than the sealing materials formed in Comparative Examples 1 to 3. Therefore, the semiconductor device (sealing material) formed using Examples 1 to 8 has a smaller number of voids than the semiconductor device (sealing material) formed using Comparative Examples 2 and 3. The semiconductor devices formed using Examples 1 to 8 were able to have higher moisture resistance reliability and reflow resistance than the semiconductor devices formed using Comparative Examples 1 to 3.

[0038]

As described above, according to the first aspect of the present invention, an epoxy resin composition containing an epoxy resin, a curing agent, a curing accelerator and a filler has a shear rate of 5%.
When the logarithm of the viscosity with respect to the measurement time is plotted under the condition of (1 / sec), a viscosity logarithmic line is formed, and the viscosity at the measurement time of 0 second is η0, and the slope of a substantially linear portion of the viscosity logarithmic line is Cs. , Η0 is 100 to 3000 poise, Cs is 0.1 or less, and the filler is contained such that the content of the filler with respect to the total volume of the epoxy resin composition molded product is 70 to 88% by volume in terms of true specific gravity. Therefore, by setting η0 to 100 to 3000 poise and Cs to 0.1 or less, it is possible to suppress a rise in viscosity and obtain good fluidity and moldability, and to displace the stage of the lead frame and die pad during molding. And wire sweep, voids and voids are less likely to be generated.
By increasing the volume to 0 to 88% by volume, a sealing material having a low coefficient of thermal expansion and a low moisture absorption and a high thermal conductivity can be formed.

Further, according to the second aspect of the present invention, η
0 is 100 to 1500 poise, Cs is 0.04 or less, and the filler is contained such that the content of the filler with respect to the total volume of the epoxy resin composition molded product is 73 to 88% by volume in terms of true specific gravity. In addition, good fluidity and moldability can be obtained by further suppressing the rise in viscosity, and the stage displacement and wire sweep of the lead frame and die pad during molding and wire and voids and voids can be further reduced. Yes, and the filler content is 73 to 88
By increasing the percentage by volume, it is possible to form a sealing material having a lower thermal expansion coefficient and a lower moisture absorption rate and a higher thermal conductivity, and the moisture resistance reliability and reflow resistance of a large or thin semiconductor device. Can be higher.

According to a third aspect of the present invention, the filler is compression-molded at a pressure at which the average particle diameter of the powder constituting the filler is maintained, thereby forming a filler compact. Since the filler was used such that the net volume percentage of the filler powder in the apparent volume of the molded body was 83% or more, the increase in viscosity (the increase in η0) was further suppressed, and good fluidity and moldability were obtained. Thus, the stage displacement and wire sweep of the lead frame and the die pad portion at the time of molding, and the occurrence of voids and voids can be suppressed.

In the invention according to claim 4 of the present invention, since the viscosity of the resin component of the epoxy resin and the curing agent at 150 ° C. is 2 poise or less, the increase in the viscosity (the increase in η0) can be further suppressed. The fluidity and the moldability can be obtained, and the stage displacement and the wire sweep of the lead frame and the die pad portion at the time of molding, and the occurrence of voids and voids can be suppressed.

In the invention according to claim 5 of the present invention, since at least one selected from diazabicycloundecene, diazabicyclononane and imidazole compounds is used as a curing accelerator, the viscosity increase (Cs ) Can be obtained, and good flowability and moldability can be obtained, and the stage displacement and wire sweep of the lead frame and the die pad portion at the time of molding, as well as cavities and voids can be suppressed.

In the invention according to claim 6 of the present invention, since the fatty acid or fatty acid derivative having 26 or less carbon atoms is contained in an amount of 0.05 to 5% by weight based on the total weight, an increase in viscosity (an increase in η0) is achieved. ) Can be further suppressed to obtain good fluidity and moldability, and the stage displacement and wire sweep of the lead frame and the die pad portion at the time of molding, and the occurrence of voids and voids can be suppressed.

According to a seventh aspect of the present invention, since the semiconductor element is sealed by transfer molding with the epoxy resin composition of the first to sixth aspects, the moisture resistance reliability and the reflow resistance are improved. Can be done.

[Brief description of the drawings]

FIG. 1 is a graph showing the change over time of the logarithm of the viscosity of the epoxy resin composition of the present invention.

[Explanation of symbols]

 A Viscosity logarithmic line B Substantially linear part

Claims (7)

[Claims] 1. An epoxy resin composition containing an epoxy resin, a curing agent, a curing accelerator and a filler, in which the logarithm of the viscosity with respect to the measurement time is plotted under the condition that the shear rate is 5 (1 / second). When a logarithmic line is formed and the viscosity at the measurement time of 0 second is η0, and the slope of a substantially linear portion of the viscosity logarithmic line is Cs, η0 is 100 to 3000 poise and Cs is 0.1.
An epoxy resin composition, comprising: a filler so that the content of the filler with respect to the total volume of the epoxy resin composition molded article is 70 to 88% by volume in terms of true specific gravity. 2. Filling so that η0 is 100 to 1500 poise and Cs is 0.04 or less, and the content of the filler relative to the total volume of the epoxy resin composition molded product is 73 to 88% by volume in terms of true specific gravity. The epoxy resin composition according to claim 1, comprising a material. 3. A filler molding is formed by compression molding the filler at a pressure that maintains the average particle diameter of the powder constituting the filler, and the filler powder occupies an apparent volume of the filler molding. The epoxy resin composition according to claim 1, wherein the filler is used such that the net volume percentage of the resin is 83% or more. 4. One of the resin components of the epoxy resin and the curing agent
The epoxy resin composition according to any one of claims 1 to 3, wherein the viscosity at 50 ° C is 2 poise or less. 5. The epoxy according to claim 1, wherein at least one selected from diazabicycloundecene, diazabicyclononane and imidazole compounds is used as a curing accelerator. Resin composition. 6. The epoxy resin according to claim 1, wherein said epoxy resin contains a fatty acid or fatty acid derivative having 26 or less carbon atoms in an amount of 0.05 to 5% by weight based on the total weight. Composition. 7. A semiconductor device comprising a semiconductor element encapsulated by transfer molding with the epoxy resin composition according to claim 1.