JP2000265038A - Epoxy resin composition for semiconductor encapsulation and semiconductor device using the same - Google Patents

Abstract

(57) [Problem] To provide an epoxy resin composition for semiconductor encapsulation capable of obtaining a semiconductor device excellent in both heat dissipation and moisture resistance. An epoxy resin (component (A)), a phenol resin (component (B)), and alumina powder (component (C))
The cured product is an epoxy resin composition for semiconductor encapsulation having the following property (α). (Α) The sodium ion content in the extraction water of the cured epoxy resin composition is 50 ppm or less, the chloride ion content is 30 ppm or less, and the fluorine ion content is 2
0 ppm or less, and the electric conductivity of the extraction water is 100 ppm or less.
μS / cm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for semiconductor encapsulation having excellent heat conductivity and moisture resistance, a cured product thereof, and a semiconductor device.

[0002]

2. Description of the Related Art Semiconductor elements such as transistors, ICs and LSIs are usually sealed in a ceramic package or a plastic package to form a semiconductor device. Since the ceramic package itself has heat resistance and excellent moisture permeability, the ceramic package is resistant to temperature and humidity and can be sealed with high reliability. However, the construction materials are relatively expensive,
Due to the drawback of inferior mass productivity, resin sealing using the above plastic package has recently become the mainstream. An epoxy resin composition has conventionally been used for this type of plastic package material. One of the characteristics required for a sealing material made of such an epoxy resin composition is that it has excellent heat dissipation.

[0003]

In order to meet the above-mentioned demand for excellent heat dissipation, for example, alumina powder has been conventionally used as a component of the epoxy resin composition. However, by using the alumina powder, a desired good result can be obtained in terms of heat dissipation, but on the other hand, there is a problem that the alumina powder itself is inferior in moisture resistance. in this way,
In fact, a sealing material having excellent heat dissipation and good moisture resistance has not yet been obtained.

The present invention has been made in view of such circumstances, and an epoxy resin composition for semiconductor encapsulation, a cured product thereof, and a semiconductor capable of obtaining a semiconductor device excellent in both heat dissipation and moisture resistance. Its purpose is to provide a device.

[0005]

According to the present invention, there is provided an epoxy resin composition for encapsulating a semiconductor, comprising the following components (A) to (C): The first gist is an epoxy resin composition for semiconductor encapsulation having the following property (α). (A) Epoxy resin. (B) a phenolic resin. (C) alumina powder. (Α) The sodium ion content in the extraction water of the cured epoxy resin composition is 50 ppm or less, the chloride ion content is 30 ppm or less, the fluorine ion content is 20 ppm or less, and the electric conductivity of the extraction water is 100 μS / cm. Less than.

A second aspect of the present invention is a semiconductor device in which a semiconductor element is sealed using the above-described epoxy resin composition for semiconductor sealing.

[0007] In the present invention, the above-mentioned "extracted water of the cured epoxy resin composition" refers to a powdered product of the cured epoxy resin composition and 10 times the amount of pure water of the powdered product in an extraction container. The extracted water is extracted from the container at 160 ° C. for 20 hours.

That is, the inventor of the present invention has intensively studied a sealing material capable of obtaining excellent heat dissipation as well as good moisture resistance. Then, in the course of the research, as a result of repeated studies to find the cause of the decrease in the moisture resistance, the physical properties of the cured product of the obtained sealing material, the impurity ion concentration and the electric conductivity in the extraction water were determined as described above. It has been found that it greatly contributes to a decrease in moisture resistance. Further, as a result of further study focusing on the impurity ion concentration and the electric conductivity, the impurity ions in the extraction water extracted from the cured body of the epoxy resin composition containing the alumina powder together with the epoxy resin and the phenol resin are found. When the respective concentrations of sodium ion, chlorine ion and fluorine ion are set to specific values or less and the electric conductivity of the extracted water is set to specific values or less, a semiconductor device obtained by sealing with the sealing material is obtained. Have found that they have excellent heat dissipation properties and can prevent a decrease in moisture resistance, and have reached the present invention.

Further, by using butadiene rubber particles together with the above-mentioned components as constituents of the epoxy resin composition for semiconductor encapsulation, it is possible to obtain even better low stress properties.

Further, among the above-mentioned specific alumina powders, by using spherical alumina powders, good fluidity can be obtained and mold abrasion becomes excellent.

[0011]

Next, embodiments of the present invention will be described in detail.

The epoxy resin composition for semiconductor encapsulation of the present invention is obtained by using an epoxy resin (component A), a phenol resin (component B), and an alumina powder (component C). It is in the form of a tablet or tablet.

The epoxy resin (component (A)) is not particularly limited, and various conventionally known epoxy resins can be used. For example, cresol novolak type epoxy resin, phenol novolak type epoxy resin, novolak bis A type epoxy resin, bisphenol A type epoxy resin, dicyclopentadiene type epoxy resin, biphenyl type epoxy resin and the like can be mentioned. These may be used alone or in combination of two or more.

The phenol resin (component B) used together with the above component A acts as a curing agent for the epoxy resin, and is not particularly limited, and various conventionally known phenol resins can be used. For example, phenol novolak, cresol novolak, bisphenol A
Type novolak, naphthol novolak, phenol aralkyl resin and the like. These may be used alone or in combination of two or more.

The mixing ratio of the epoxy resin (component A) and the phenol resin (component B) is such that the hydroxyl group in the phenol resin is 0.8 per equivalent of epoxy group in the epoxy resin.
It is preferable to mix them so that the amount becomes to 1.2 equivalents.
More preferred is 0.9 to 1.1 equivalents.

The alumina powder (component C) used together with the above components A and B is not particularly limited, and ordinary alumina powder is used. For example, it is preferable to use one having the following properties. It is preferable from the viewpoint of the above. That is, it is an alumina powder in which each ion (Na ⁺ , Cl ⁻ , F ⁻ ) in the extraction water of the alumina powder is equal to or less than a specific value. More specifically, the extraction water of the alumina powder has a sodium ion concentration of 50 ppm or less, a chloride ion concentration of 0.25 ppm or less, and a fluorine ion concentration of 20 ppm or less. Particularly preferably, the extraction water has a sodium ion concentration of 30 ppm or less, a chloride ion concentration of 0.2 ppm or less, and a fluorine ion concentration of 10 ppm or less.
pm or less. Usually, the concentration of sodium ion in the extraction water is 10 to 20 ppm, and the concentration of chloride ion is 0.1 ppm.
08-0.12ppm, Fluorine ion concentration is 6-10p
pm. As described above, when each ion concentration (content) is equal to or less than the above value, the semiconductor device using the obtained epoxy resin composition becomes excellent in both heat dissipation and moisture resistance.

The measurement of the impurity ions is performed as follows. That is, pure water of 10 times the weight of the alumina powder to be measured is added to the alumina powder, and 160 ° C. ×
Extraction is performed under the conditions of 20 hours, and each ion concentration is analyzed and measured by ion chromatography using the extracted water. The ion chromatography includes, for example, DX-10 manufactured by Dionex.
0 is used.

Among the above-mentioned specific alumina powders, the use of spherical alumina powder provides good fluidity,
It is preferable from the viewpoint of mold abrasion resistance. The spherical alumina powder has a roundness of 0.7 to 0.7.
It is preferably 1.0. Particularly preferably, the roundness is 0.8 to 1.0. The above-mentioned circularity of 0.7 to 1.0 means that in the definition of the circularity described below, 0.
7 to 1.0, which is closer to a perfect circle. The roundness is calculated as follows. That is, as shown in FIG. 1, in a projected image 1 (see FIG. 1A) of an object whose roundness is to be measured, its actual area is represented by α, and the length around the projected image 1 is represented by PM. , The same length as that of the projected image 1
Assume a projected image 2 of a perfect circle (see FIG. 1B).
Then, the area α ′ of the projection image 2 is calculated. As a result, the ratio (α / α ′) between the actual area α of the projection image 1 and the area α ′ of the projection image 2 indicates roundness, and this value (α / α ′) is calculated by the following equation (1). Is calculated. Therefore, a roundness of 1.0 can be said to be a perfect circle as is clear from this definition. Then, the more irregularities are on the outer periphery of the object, the smaller the roundness becomes sequentially smaller than 1.0. In the present invention, the roundness of the spherical alumina powder is a value obtained by extracting a part of the spherical alumina powder to be measured and measuring by the above method, and is usually an average roundness. Say. The average particle size of the spherical alumina powder is preferably in the range of 10 to 50 μm, and particularly preferably 2 to 50 μm.
0 to 40 μm. The average particle size can be measured by, for example, a laser type particle size measuring device.

[0019]

(Equation 1)

The content ratio of the alumina powder (component C) is preferably set in the range of 50 to 92% by weight, particularly preferably 70 to 88% by weight in the whole epoxy resin composition.
% By weight. That is, if the content of the alumina powder (component C) is less than 50% by weight and too small, it becomes difficult to obtain a desired heat dissipation property, and if it exceeds 92% by weight, the fluidity tends to decrease. Is seen.

Further, butadiene rubber particles (component D) may be blended together with the above components A to C. By blending the butadiene-based rubber particles, the effects of lowering stress and improving thermal shock resistance can be obtained. As the above-mentioned butadiene rubber particles, those obtained by a copolymerization reaction of alkyl methacrylate, alkyl acrylate, butadiene, styrene and the like are usually used. For example, methyl acrylate-butadiene-styrene copolymer, methyl acrylate-butadiene-vinyltoluene copolymer, butadiene-styrene copolymer, methyl methacrylate-butadiene-styrene copolymer, methyl methacrylate-butadiene-vinyl Examples thereof include a toluene copolymer, a methyl methacrylate-ethyl acrylate-butadiene-styrene copolymer, a butadiene-vinyltoluene copolymer, and an acrylonitrile-butadiene copolymer. Among the above copolymers, it is preferable to use a methyl methacrylate-butadiene-styrene copolymer, and particularly a methacrylic acid having a butadiene composition ratio of 70% by weight or less and a methyl methacrylate composition ratio of 15% by weight or more. An acid methyl-butadiene-styrene copolymer is preferably used.
Particularly preferably, the composition ratio of butadiene is 40 to 70% by weight, and the total composition ratio of methyl methacrylate and styrene is 30 to 60% by weight. In this case, the composition ratio (weight ratio) of methyl methacrylate to styrene is preferably in the range of 0.5 to 2.0 with respect to 1 of methyl methacrylate.

Further, as the butadiene rubber particles (component D), those having a core-shell structure are preferably used. The butadiene-based rubber particles having the core-shell structure are such that a core portion as a core is formed of particles made of butadiene-based rubber, and a shell portion made of a polymer resin is formed on the outer surface of the core so as to cover the core. (Outer layer). Examples of butadiene-based rubbers that are the core forming materials include styrene-butadiene copolymer latex and acrylonitrile-butadiene copolymer latex. Examples of the polymer resin that is a material for forming the outer layer that coats the nucleus include a polymer resin having a glass transition temperature of 70 ° C. or higher, and this polymer resin has an unsaturated double bond. Obtained by polymerization of a saturated monomer. Examples of the unsaturated monomer include methyl methacrylate, acrylonitrile, styrene and the like. The butadiene rubber particles having such a core-shell structure are obtained by, for example, an aqueous medium polymerization method. More specifically, butadiene-based rubber particles serving as nuclei are prepared by mixing and polymerizing butadiene-based rubbers, which are the core-forming materials, and water. Next, in this aqueous medium, an unsaturated monomer to be a material for forming the outer layer is added, and the surface of the butadiene rubber as the nucleus is graft-copolymerized with the unsaturated monomer. Butadiene rubber particles having a core-shell structure can be obtained by laminating them on the outer peripheral surface of the core. As the butadiene rubber particles having such a core-shell structure, those having a core (core) portion made of a styrene-butadiene copolymer and a shell portion made of methyl methacrylate or methyl methacrylate and styrene are particularly preferable. As described above, the composition ratio of the butadiene is 70% by weight or less,
Those having a composition ratio of methyl methacrylate of 15% by weight or more are preferred. Particularly preferably, the composition ratio of butadiene is 4
0 to 70% by weight, and the total composition ratio of methyl methacrylate and styrene is 30 to 60% by weight. in this case,
The composition ratio (weight ratio) of methyl methacrylate to styrene is 0.5 to 2.
It is preferably in the range of 0.

The mixing ratio of the butadiene rubber particles (D component) is 0.1 to 5% by weight in the whole epoxy resin composition.
Is preferably set in the range, more preferably 0.1.
5 to 2% by weight. That is, if the mixing ratio of the butadiene-based rubber particles (D component) is too small, it is difficult to obtain a desired low stress effect, while if too large, the fluidity tends to be too low.

The epoxy resin composition for semiconductor encapsulation of the present invention may contain, if necessary, an inorganic filler other than the alumina powder, a silane coupling agent, a curing accelerator, and a release agent together with the above-mentioned components A to D. Various additives such as a flame retardant, a flame retardant auxiliary, and a colorant such as carbon black are appropriately blended.

The inorganic filler other than the above-mentioned alumina powder is not particularly limited, and conventionally known inorganic fillers may be used. Examples thereof include silica powder such as fused silica powder and crystalline silica powder, talc, calcium carbonate, boron nitride and the like. , Silicon nitride and the like. These may be used alone or in combination of two or more.

Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane and the like.

The curing accelerator is an imidazole such as 2-methylimidazole, 1,8-diazabicyclo (5,
Tertiary amines such as (4,0) undecene-7 (DBU);
And organic phosphorus compounds.

The release agents include long-chain carboxylic acids such as stearic acid and palmitic acid; metal salts of long-chain carboxylic acids such as zinc stearate and calcium stearate; waxes such as carnauba wax and montan wax; Waxes and the like.

Examples of the flame retardant include brominated epoxy resins.

The flame retardant aid includes diantimony trioxide, antimony pentoxide and the like.

The epoxy resin composition for semiconductor encapsulation of the present invention further contains, in addition to the above additives, an ion trapping agent such as hydrotalcite for the purpose of improving reliability in a moisture resistance reliability test. May be.

The epoxy resin composition for semiconductor encapsulation of the present invention can be produced, for example, as follows.
That is, the epoxy resin (A component), the phenol resin (B component), the specific alumina powder (C component), and optionally butadiene-based rubber particles (D component), and if necessary, various additives are added in appropriate proportions. Formulated with
Premix. Then, the mixture is kneaded in a heated state by a kneading machine such as a mixing roll machine and melt-mixed. Then, after cooling to room temperature, it can be manufactured by a series of steps of pulverizing by a known means and tableting as required.

The content of impurity ions in the cured product using the epoxy resin composition obtained as described above is set as follows. That is, in the extraction water of the cured epoxy resin composition, the sodium ion content is 50 ppm or less, and the chloride ion content is 30 ppm.
Hereinafter, the fluorine ion content is 20 ppm or less. Particularly preferably, in the extraction water of the cured epoxy resin composition,
Sodium ion content is 20 ppm or less, chloride ion content is 20 ppm or less, fluorine ion content is 15 p
pm or less. Further, the electric conductivity of the extracted water is 100
μS / cm or less. Usually, the sodium ion content in the extraction water is 3 to 15 ppm, the chlorine ion content is 5 to 15 ppm, and the fluorine ion content is 0.3 to 1.
0 ppm, and the electric conductivity of the extraction water is 40 to 6
0 μS / cm. That is, when the amount of impurity ions and the electric conductivity of the extraction water of the cured epoxy resin composition have the above values, the obtained semiconductor device has excellent moisture resistance.

Each impurity ion contained in the cured epoxy resin composition is measured as follows.
That is, 5 g of the powdered cured product of the epoxy resin composition and 50 cc of pure water were placed in a dedicated extraction container, and this container was placed in a 16-cm container.
Leave it in a dryer at 0 ° C for 20 hours to extract water (pH 6.0).
~ 8.0). Then, the extracted water is analyzed by ion chromatography to measure the amount of each ion (α). In addition, the pH of the said extraction water has the preferable range of 6.0-8.0. Further, in the preparation of the epoxy resin composition cured product, the cured product molding conditions are preferably set to 175 ° C. × 2 minutes for post-curing and 175 ° C. × 5 hours for post-curing. . In addition, for the measurement of the extracted water by ion chromatography, for example, DX-100 manufactured by Dionex is used as in the measurement of the alumina powder described above. The electric conductivity was measured using the extracted water according to the NIS-TM-521M method. For example, Advantech (A) was used as an electric conductivity meter.
(DVANTEC) can be used for the measurement.

The method for encapsulating a semiconductor device using the epoxy resin composition obtained by the above-mentioned production is not particularly limited, and it can be carried out by a known molding method such as ordinary transfer molding.

Next, examples will be described together with comparative examples.

First, prior to the preparation of the epoxy resin composition, the following components were prepared.

[Epoxy resin] o-cresol novolak type epoxy resin (epoxy equivalent 195, softening point 70 ° C)

[Brominated epoxy resin] Brominated epoxy resin (epoxy equivalent 450, softening point 8
1 ℃)

[Phenol resin] Phenol novolak resin (hydroxyl equivalent 105, softening point 83 ° C)

[DBU] 1,8-diazabicyclo (5,4,0) undecene-7

[Spherical Alumina Powder] Spherical alumina powders ad shown in Table 1 below were prepared. The concentration of each ionic impurity in the spherical alumina powder was determined according to the method described above by using DX-10 manufactured by Dionex.
It measured using 0.

[0043]

[Table 1]

[Silane coupling agent] γ-glycidoxypropyltrimethoxysilane

[Butadiene rubber] Methyl methacrylate-butadiene-styrene copolymer having an average primary particle size of 0.2 μm

[0046]

Examples 1 to 7 and Comparative Examples 1 to 4 Raw materials shown in the following Tables 2 and 3 were blended in the proportions shown in the same table and kneaded at 100 ° C. for 3 minutes using a mixing roll machine to form a sheet composition. I got something. Then, the sheet-like composition was pulverized to obtain a target powdery epoxy resin composition.

[0047]

[Table 2]

[0048]

[Table 3]

Using each of the above epoxy resin compositions, the spiral flow value and the thermal conductivity were measured according to the following methods. The results are shown in Tables 4 and 5 below.

[Spiral Flow Value] EMMI 1-6 at 175 ± 5 ° C. using a spiral flow measuring mold.
The spiral flow value was measured according to 6.

[Thermal Conductivity] Using each epoxy resin composition, a cured product having a size of 80 × 50 × 20 mm was prepared (conditions: heat curing at 175 ° C. × 2 minutes, post-curing at 175 ° C. × 5 hours). ). Then, the thermal conductivity (λ) of the cured product is measured by a thermal conductivity measuring device (QTM-D3, manufactured by Kyoto Electronics Industry Co., Ltd.).
It measured using.

Further, a cured product of each of the obtained epoxy resin compositions was prepared (conditions: heat curing at 175 ° C. × 2 minutes, 1
(Post-curing at 75 ° C. for 5 hours), and the content of the impurity ions was measured according to the measurement method described above. In addition, in the ion chromatographic analysis for measuring the impurity ion content,
DX-100 manufactured by Dionex was used. The electric conductivity was measured using an electric conductivity measuring device manufactured by ADVANTEC.

Further, in order to evaluate the moisture resistance reliability of the sealing resin, a semiconductor element (size: 3 mm × 5 mm) on which an aluminum electrode was deposited was used for a 16-pin dual in-line package (abbreviated as “DIP-16”). And wire bonding was performed. Then, ten semiconductor devices were obtained by resin sealing using the above epoxy resin compositions (conditions: heat curing at 175 ° C. × 2 minutes, post-curing at 175 ° C. × 5 hours). After conducting an initial conduction test of the semiconductor device, the passed product is further exposed to a high-temperature and high-humidity condition of 125 ° C./85% RH, and a bias voltage of 30 V is applied (pressure cooker bias test (PCBT)). The occurrence of open failure (disconnection) was confirmed at regular intervals, and the time at which the occurrence occurred was measured. This measurement was performed for 10 packages for one epoxy resin composition.
It was determined as an average time of 10 pieces. The results are shown in Table 4 below.
And Table 5.

[0054]

[Table 4]

[0055]

[Table 5]

From the above Tables 4 and 5, it can be seen that the products of the Examples have an appropriate spiral flow value and are excellent in fluidity. Furthermore, the thermal conductivity is high and P
Since the average life time of the CBT is long, it can be seen that the device has excellent heat dissipation and good moisture resistance.

On the other hand, the product of Comparative Example has an appropriate spiral flow value and a high thermal conductivity, so that it has excellent fluidity and heat dissipation, but has a short average life due to PCBT. This indicates that the moisture resistance is poor.

[0058]

As described above, the present invention comprises an epoxy resin (component A), a phenolic resin (component B), and an alumina powder (component C). An epoxy resin composition for semiconductor encapsulation having an electric conductivity of not more than a specific value at a specific value or less. For this reason, a semiconductor device in which a semiconductor element is sealed using the semiconductor device has excellent heat dissipation and good moisture resistance, and is a highly reliable semiconductor device.

Further, by using butadiene rubber particles (D component) together with the above components as the epoxy resin composition for semiconductor encapsulation, it is possible to obtain even better low stress properties.

Further, among the above-mentioned alumina powders (component C), the use of spherical alumina powders has high fluidity and excellent mold wear.

[Brief description of the drawings]

1 (a) and 1 (b) are explanatory diagrams showing a method for measuring the roundness of a spherical alumina powder.

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Claims (4)

[Claims] 1. An epoxy resin composition for semiconductor encapsulation containing the following components (A) to (C), wherein the cured product has the following characteristic (α): Epoxy resin composition for use. (A) Epoxy resin. (B) a phenolic resin. (C) alumina powder. (Α) The sodium ion content in the extraction water of the cured epoxy resin composition is 50 ppm or less, the chloride ion content is 30 ppm or less, the fluorine ion content is 20 ppm or less, and the electric conductivity of the extraction water is 100 μS / cm. Less than. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, further comprising the following component (D) in addition to the components (A) to (C). (D) Butadiene rubber particles. 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the alumina powder as the component (C) is a spherical alumina powder. 4. A semiconductor device comprising a semiconductor element encapsulated by using the epoxy resin composition for semiconductor encapsulation according to claim 1.