JP2006257309A - Epoxy resin composition for sealing semiconductor and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition for sealing semiconductor small in die wear in sealing and molding a semiconductor device, having a high heat conductivity and a high reliability to wet resistance. <P>SOLUTION: The invention relates to the epoxy resin composition comprising (A) the epoxy resin, (B) a phenol resin, (C) a hardening accelerator and (D) magnesium oxide surface treated by an inorganic compound, wherein the cured product of the resin composition preferably, has 0.1-1 wt%. of water absorption in soaking in boiling water for 24 hrs at 100°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an epoxy resin composition for semiconductor encapsulation and a semiconductor device using the same.

Metal cans, ceramics, epoxy resin compositions, and the like are used for sealing semiconductor elements such as ICs, LSIs, and transistors. Among them, a sealing method by transfer molding of an epoxy resin composition is suitable for low cost and mass production and widely used. In terms of reliability, improvement of moisture resistance and solder reflow have been achieved by improving epoxy resins and phenolic resins as curing agents.
However, with the recent increase in functionality and speed of electronic devices, the amount of heat generated by semiconductor devices tends to increase. For this reason, there is an increasing demand for high heat dissipation properties for the epoxy resin composition for semiconductor encapsulation, and various studies are being made on the inorganic filler constituting the resin composition. To date, electronic devices that require high heat dissipation have used an epoxy resin composition for semiconductor encapsulation (hereinafter, also referred to as “encapsulant”) containing crystalline silica or alumina as an inorganic filler. It was. However, although the thermal conductivity of crystalline silica and alumina is higher than that of fused silica widely used for sealing materials, it is not sufficient, and it has not been able to meet the recent demand for higher speed. On the other hand, aluminum nitride and silicon nitride themselves have a high thermal conductivity of 100 W / m · K or more, but there are concerns about problems such as significant wear of the mold during molding and deterioration of moisture resistance reliability. It has not yet reached widespread use. Examples of the filler that can achieve both thermal conductivity and mold wear include magnesium oxide. Magnesium oxide has a thermal conductivity of 48 W / m · K, which is higher than that of alumina (30 W / m · K), has a Mohs hardness of 6, has little effect on mold wear, and requires high heat dissipation. Although it has desirable characteristics as a filler for materials, it has a drawback of reducing the moisture resistance reliability of the sealing material. In order to overcome this drawback, a technique for reducing impurities in magnesium oxide has been proposed (see, for example, Patent Document 1), but the hygroscopic property itself of magnesium oxide itself has not been improved, and the temperature is high. The phenomenon that cracks occur in a semiconductor device due to volume expansion accompanying the change of magnesium oxide to magnesium hydroxide under high humidity has not been solved. As another means, a technique for hydrophobizing with an organic surface treatment agent such as a silane coupling agent has been proposed (see, for example, Patent Document 2). However, the moisture resistance was improved but not sufficient.

JP 2001-214065 A (pages 2 to 8) JP 05-063116 A (pages 2 to 5)

  The present invention has been made in order to solve the conventional problems. The object of the present invention is to reduce the wear of the mold at the time of sealing molding of a semiconductor element, to have high thermal conductivity, and to be reliable against moisture. The present invention provides an epoxy resin composition for semiconductor encapsulation having a high level and a semiconductor device using the same.

The present invention
[1] An epoxy resin composition for semiconductor encapsulation, comprising: an epoxy resin, (B) a phenol resin, (C) a curing accelerator, and (D) magnesium oxide subjected to a surface treatment with an inorganic substance,
[2] In the epoxy resin composition according to item [1], the moisture absorption when the cured product of the resin composition is immersed in boiling water at 100 ° C. for 24 hours is 0.1 wt% or more and 1 wt% Epoxy resin composition for semiconductor encapsulation which is:
[3] The epoxy resin composition for semiconductor encapsulation according to the item [1] or [2], wherein the particle shape of the magnesium oxide surface-treated with the inorganic substance (D) is spherical. ,
[4] A semiconductor device comprising a semiconductor element sealed using the epoxy resin composition for semiconductor sealing according to any one of [1] to [3],
It is.

  According to the present invention, it is possible to obtain an epoxy resin composition for encapsulating a semiconductor that has little mold wear during encapsulating of a semiconductor element, has high thermal conductivity, and has high moisture resistance reliability.

The present invention contains epoxy resin, phenolic resin, curing accelerator, and magnesium oxide that has been surface-treated with an inorganic substance, so that there is less mold wear during sealing molding of semiconductor elements, and high thermal conductivity. Moreover, an epoxy resin composition for semiconductor encapsulation having high moisture resistance and reliability can be obtained.
Hereinafter, the present invention will be described in detail.

  Epoxy resins used in the present invention are monomers, oligomers, and polymers in general having two or more epoxy groups in one molecule, and the molecular weight and molecular structure are not particularly limited. For example, biphenyl type epoxy resin, bisphenol type epoxy resin, stilbene type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, triphenolmethane type epoxy resin, alkyl-modified triphenolmethane type epoxy resin, triazine nucleus-containing epoxy resin Dicyclopentadiene-modified phenol type epoxy resin, phenol aralkyl type epoxy resin (having a phenylene skeleton, a biphenylene skeleton, or the like) can be used. In the above-mentioned epoxy, biphenyl type epoxy resin and bisphenol type epoxy resin are preferably used, but not limited thereto. Two or more types of epoxy may be mixed.

  The phenol resin used in the present invention is a monomer, oligomer or polymer in general having two or more phenolic hydroxyl groups in one molecule, and its molecular weight and molecular structure are not particularly limited. For example, phenol novolak resin, cresol novolak resin, dicyclopentadiene modified phenol resin, terpene modified phenol resin, triphenolmethane type resin, phenol aralkyl resin (having phenylene skeleton, biphenylene skeleton, etc.) and the like can be mentioned. A mixture may be used.

  The blending amount of the epoxy resin and the phenol resin is not particularly limited, but the ratio of the number of epoxy groups of all epoxy resins to the number of phenolic hydroxyl groups of all phenol resins is 0.8 or more and 1.3 or less. Preferably, outside this range, there is a possibility that the curability of the epoxy resin composition is lowered, the glass transition temperature of the cured product is lowered, the moisture resistance reliability is lowered, or the like.

  As a hardening accelerator used for this invention, what is necessary is just to accelerate | stimulate the hardening reaction of an epoxy group and a phenolic hydroxyl group, and what is generally used for a sealing material can be used. Examples thereof include 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, 2-methylimidazole, tetraphenylphosphonium / tetraphenylborate, triphenylphosphine adducted with benzoquinone, and the like. However, they can be mixed and used.

  In the present invention, magnesium oxide that has been surface-treated with an inorganic substance is used as the inorganic filler. The surface treatment with an inorganic substance means that the surface of magnesium oxide is coated with a fine inorganic substance powder such as silica or alumina that is sufficiently smaller than the particle diameter of magnesium oxide. Specific surface treatment methods include a method of fixing fine silica, fine alumina, etc. on the surface of magnesium oxide by high-speed stirring using Henschel, a super mixer, etc., or shearing using a compression roll, etc. Examples thereof include a method of mechanically pressing fine silica, fine alumina and the like against the surface of magnesium oxide by pressurization, but are not limited thereto. Magnesium oxide has high hygroscopicity, and when a semiconductor element or the like is sealed using a sealing material containing magnesium oxide, the reliability of electronic components is greatly impaired under high temperature and high humidity. However, the surface treatment with the inorganic material applied as described above can greatly reduce the hygroscopicity of magnesium oxide, thereby greatly improving the moisture resistance of the sealing material. The effect of improving the moisture resistance varies depending on the strength of the surface coating layer, and the surface coating layer can be easily formed by the shearing force in the sealing material manufacturing process in the surface treatment with an organic substance such as a coupling agent of the prior art. Although it is destroyed and a sufficient effect of improving the moisture resistance cannot be obtained, the surface treatment with the inorganic substance of the present invention does not cause the above-described destruction and can sufficiently exhibit the effect of improving the moisture resistance.

  In the magnesium oxide surface-treated with the inorganic substance used in the present invention, the compounding ratio of the inorganic substance to the magnesium oxide varies depending on the particle shape, particle size distribution, etc. of the magnesium oxide and the inorganic substance, and is not particularly limited. However, it is desirable that the blending ratio of the inorganic substance is sufficient to cover at least the surface of magnesium oxide. Moreover, the said mixture ratio can also be determined to such an extent that sufficient moisture-proof improvement effect is acquired in the characteristic evaluation at the time of setting it as a sealing material.

The shape of the magnesium oxide subjected to the surface treatment with the inorganic material used in the present invention is not particularly limited, but it is preferable to use a spherical one. In the case of crushed materials, not only does the moisture resistance decrease due to an increase in the surface area, but the original purpose of high thermal conductivity cannot be sufficiently achieved due to a decrease in the filling amount of magnesium oxide that has been surface-treated with an inorganic substance. There is a fear. In addition, in terms of mold wear, a spherical shape is more advantageous than a crushed shape.
Moreover, the compounding quantity of the magnesium oxide surface-treated with the inorganic substance used for this invention is although it does not specifically limit, 70 to 95 weight% is preferable in all the epoxy resin compositions. When it is within the above range, sufficient thermal conductivity and sufficient fluidity can be obtained.

Moreover, in this invention, another inorganic filler can be used together in the range which does not impair the effect which mix | blends the magnesium oxide surface-treated with the inorganic substance. As the inorganic filler to be used in combination, those which are generally used in epoxy resin compositions for semiconductor encapsulation can be used. For example, fused silica, crystalline silica, talc, alumina, silicon nitride and the like can be mentioned, and the most suitably used is spherical fused silica. These inorganic fillers may be used alone or in combination.
Further, the total blending amount of the magnesium oxide subjected to the surface treatment with the inorganic substance and the other inorganic filler is not particularly limited, but is preferably 75% by weight or more and 95% by weight or less in the total epoxy resin composition. Within the above range, good solder reflow resistance and sufficient fluidity can be obtained.

  The epoxy resin composition of the present invention comprises an epoxy resin, a phenol curing agent, a curing accelerator, and surface-treated magnesium oxide as essential components, but in addition to this, epoxy silane, mercaptosilane, aminosilane, alkylsilane, Silane coupling agents such as ureido silane and vinyl silane, colorants such as carbon black, mold release agents such as natural wax and synthetic wax, low stress additives such as rubber, brominated epoxy resin, antimony trioxide, aluminum hydroxide, etc. Various additives such as flame retardants and inorganic ion exchangers such as bismuth oxide hydrate may be appropriately blended.

In addition, the epoxy resin composition of the present invention is obtained by mixing the raw materials sufficiently uniformly using a mixer or the like, and then melt-kneading with a kneader such as a hot roll or a kneader, cooling and pulverizing to form a powder. And Depending on the molding method, the obtained powder is further compressed into a tablet and used.
The epoxy resin composition of the present invention is used to encapsulate various electronic components such as semiconductor elements, and to manufacture semiconductor devices by conventional molding methods such as transfer molding, compression molding, and injection molding. do it.

Examples of the present invention are shown below, but the present invention is not limited thereto. The blending ratio is parts by weight.
Example 1
Biphenyl epoxy resin [epoxy equivalent 195 g / eq, softening point 55 ° C., melt viscosity (150 ° C.) 0.02 Pa · s] 12.77 parts by weight Aralkylphenol novolac resin A [hydroxyl equivalent 175 g / eq, softening point 67 ° C., melting Viscosity (150 ° C.) 1.4 Pa · s] 11.38 parts by weight Triphenylphosphine 0.25 parts by weight Spherical magnesium oxide A [average particle size 17 μm, inorganic surface-treated product] (Pyroxuma 3320A, manufactured by Kyowa Chemical Industry Co., Ltd.) ) 75.00 parts by weight Carbon black 0.30 parts by weight Carnauba wax 0.30 parts by weight was mixed with a mixer, then kneaded at 95 ° C. for 8 minutes using a hot roll, cooled and pulverized to obtain an epoxy resin composition I got a thing. The obtained epoxy resin composition was evaluated by the following methods. The results are shown in Table 1.

Evaluation method Spiral flow: Using a low-pressure transfer molding machine, a spiral flow measurement mold conforming to EMMI-1-66, epoxy resin under conditions of a mold temperature of 175 ° C., an injection pressure of 6.9 MPa, and a curing time of 120 seconds The composition was injected and the flow length was measured. The unit is cm.

  Boiling moisture absorption: Using a transfer molding machine, a test piece having a diameter of 50 mm and a thickness of 3 mm was molded at a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 2 minutes. It was post-cured at 175 ° C./8 hr and dried at 125 ° C./20 hr to determine the dry weight. Thereafter, after immersion treatment in boiling water at 100 ° C. for 24 hours, the weight was measured again, and the increase from the dry weight was divided by the dry weight to obtain the boiling moisture absorption rate. After the boiling treatment, the broken test piece was filtered with a filter paper to collect all the pieces and measure the weight.

  Test piece crack: The above-mentioned boiling moisture absorption rate, the appearance of the test piece was observed during measurement, and cracks and cracks were confirmed.

  Moisture resistance: 16 pSOP (mold size 11 mm × 7 mm, thickness 1.95 mm, semiconductor element size 3.5 mm × 3.3) using a transfer molding machine with a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 2 minutes. (0mm, thickness 0.48mm, bonding pad of semiconductor element and 42 alloy frame are bonded at 12 places with 25μm diameter gold wire. Semiconductor element has aluminum wiring width 10μm, wiring distance 10μm, aluminum deposition thickness 1μm.) Was molded and post-cured at 175 ° C. for 2 hours to obtain a sample. After 15 semiconductor devices obtained were cooled to room temperature, 20V was applied in an environment of 140 ° C. and 85% relative humidity (6 out of 12 bonded locations were anodes and 6 locations were cathodes), treated for 200 hours, and then packaged. The resistance value of the circuit was measured by applying a tester to each terminal. When the resistance value exceeded 200% of the initial value, it was regarded as defective, and indicated as n / 15 when there were n defective portions (anode: 3 locations × 5, cathode: 3 locations × 5).

・ Thermal conductivity: Using a transfer molding machine, a molded product with a diameter of 40 mm and a thickness of 30 mm was molded at a mold temperature of 175 ° C., an injection pressure of 6.9 MPa, and a curing time of 2 minutes, and after 175 ° C. for 8 hours. It hardened | cured and the heat conductivity of the obtained molded article was measured with the heat conductivity meter (QTM-500 by Kyoto Electronics Industry Co., Ltd.). The unit is W / mK. 3 W / mK or more was accepted.

Examples 2-5, Comparative Examples 1-4
According to the composition of Table 1, an epoxy resin composition was obtained in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 1.
The components used in other than Example 1 are shown below.
Spherical magnesium oxide B [average particle size 17 μm, silane coupling surface-treated product]: Magnesium oxide C (manufactured by Kyowa Chemical Industry Co., Ltd., Pyroxuma 3320) with 100 parts by weight of silane coupling agent (Nihon Unicar A-1100) ) 10 parts by weight was mixed with a Henschel mixer to prepare magnesium oxide B.
Spherical magnesium oxide C [average particle size 17 μm, no surface treatment] (Pyroxuma 3320, manufactured by Kyowa Chemical)
Crushed magnesium oxide [average particle size 12 μm, no surface treatment]
Spherical alumina [average particle size 20 μm, no surface treatment]
Spherical fused silica [average particle size 23 μm, no surface treatment]

  According to the present invention, an epoxy resin composition for semiconductor encapsulation having a low mold wear during the molding of a semiconductor element, high thermal conductivity, and high moisture resistance reliability can be obtained. Therefore, it can be suitably used for a semiconductor device requiring high performance.

Claims (4)

An epoxy resin composition for semiconductor encapsulation, comprising (A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator, and (D) magnesium oxide subjected to a surface treatment with an inorganic substance. The epoxy resin composition according to claim 1, wherein the moisture absorption when the cured product of the resin composition is immersed in boiling water at 100 ° C. for 24 hours is 0.1 wt% or more and 1 wt% or less. Stopping epoxy resin composition. 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the particle shape of magnesium oxide that has been surface-treated with the inorganic substance (D) is spherical.   A semiconductor device comprising a semiconductor element sealed using the epoxy resin composition for semiconductor sealing according to any one of claims 1 to 3.