JP2006206748A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition for sealing a semiconductor that provides a semiconductor device excellent in moisture resistance reliability and high-temperature storability. <P>SOLUTION: The epoxy resin composition for sealing a semiconductor comprises as essential ingredients (A) an epoxy resin, (B) a phenolic resin, (C) a cure accelerator, (D) an inorganic filler and (E) active alumina, where the content of the active alumina (E) is at least 0.01 wt% and at most 5 wt% based on the whole epoxy resin composition. Preferably, the active alumina (E) is porous alumina having an average specific surface area of at least 30 m<SP>2</SP>/g and at most 400 m<SP>2</SP>/g. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an epoxy resin composition for semiconductor encapsulation and a semiconductor device. For example, it is suitably used for a semiconductor device used for outdoor equipment such as in-vehicle use that requires high moisture resistance reliability and high temperature storage.

  Conventionally, semiconductor devices have been sealed using an epoxy resin composition containing an epoxy resin excellent in heat resistance and moisture resistance reliability, a curing agent such as phenol resin, and an inorganic filler such as fused silica and crystalline silica. . However, in recent years, with the increase in the integration density of integrated circuits, the size of semiconductor elements has increased, and the semiconductor devices have changed to surface mount types such as TSOP, TQFP, BGA, etc., and the thermal stress during solder reflow is more severe than before. It has become. Surface mount semiconductor devices are prone to problems such as cracks in the semiconductor device due to thermal stress during mounting, and peeling at the interface between the semiconductor element and other constituent members and the cured epoxy resin composition, resulting in improved heat resistance. An excellent epoxy resin composition has been strongly demanded. Therefore, as an epoxy resin composition used for these surface-mount type semiconductor devices, in addition to the conventional ortho-cresol novolac type epoxy resin, a crystalline epoxy resin such as a biphenyl type epoxy resin and a low hygroscopic property can be obtained. Low molecular weight and low functional group epoxy resins such as dicyclopentadiene-modified phenolic epoxy resins have been used.

On the other hand, a large number of semiconductor devices are mounted in outdoor equipment such as automobiles, and reliability that can withstand a severer environment than that used in indoor equipment is required. Under high temperature or high humidity, ionic impurities such as chlorine ions contained in the epoxy resin composition are likely to move, and the corrosion of the semiconductor circuit is likely to proceed. Conventional epoxy resin compositions for semiconductor encapsulation are essential for automotive applications. There have been difficulties in moisture resistance reliability, which is a required item, and storage reliability (hereinafter referred to as high temperature storage property) that allows the semiconductor device to maintain its function even under a high temperature atmosphere of about 150 ° C. In order to capture the ionic impurities contained in the epoxy resin composition that causes poor moisture resistance reliability and high-temperature storage stability, proposals have been made to incorporate an ion scavenger containing a Bi-based inorganic compound (for example, , See Patent Document 1.) When the amount of the Bi-based inorganic compound added is large, both moisture resistance reliability and high-temperature storage properties are not always sufficient. In addition, as another ion scavenger, a proposal has been made to capture anionic impurities using a hydrotalcite compound (see, for example, Patent Documents 2 and 3). Although an improvement in high-temperature storage was observed, the hydrotalcite compound could not sufficiently capture ionic impurities, so that a sufficient effect of improving moisture resistance reliability could not be obtained.
Japanese Patent Laid-Open No. 11-240937 (pages 2 to 11) JP 09-157497 A (pages 2 to 6) JP 09-169830 A (pages 2 to 6)

  The present invention provides an epoxy resin composition for encapsulating a semiconductor that provides a semiconductor device excellent in moisture resistance reliability and high-temperature storage, and a semiconductor device using the same.

The present invention
[1] (A) epoxy resin, (B) phenol resin, (C) curing accelerator, (D) inorganic filler, and (E) activated alumina as essential components, the content of (E) activated alumina Is an epoxy resin composition for semiconductor encapsulation, characterized in that the total epoxy resin composition is 0.01 wt% or more and 5 wt% or less,
[2] The epoxy resin composition for semiconductor encapsulation according to item [1], wherein (E) activated alumina is porous alumina having an average specific surface area of 30 m ² / g or more and 400 m ² / g or less,
[3] A semiconductor device comprising a semiconductor element sealed using the epoxy resin composition for semiconductor sealing according to [1] or [2],
It is.

  When a semiconductor element is encapsulated with the epoxy resin composition of the present invention, both moisture resistance reliability and high-temperature storage stability, both of which are difficult to achieve with the prior art, are excellent without impairing necessary properties such as solder resistance. A semiconductor device can be obtained.

The present invention provides a semiconductor device using an epoxy resin composition containing (A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator, (D) an inorganic filler, and (E) activated alumina as essential components. By sealing the semiconductor device, it is possible to obtain a semiconductor device excellent in both moisture resistance reliability and high-temperature storage stability.
Hereinafter, the present invention will be described in detail.

  The (A) epoxy resin used in the present invention refers to monomers, oligomers, and polymers generally having two or more epoxy groups in one molecule, and is not particularly limited. For example, biphenyl type epoxy resin, stilbene type Epoxy resin, bisphenol type epoxy resin, triphenolmethane type epoxy resin, alkyl modified triphenolmethane type epoxy resin, dicyclopentadiene modified phenol type epoxy resin, triazine core-containing epoxy resin, phenol aralkyl type epoxy resin, naphthol type epoxy resin, A phenol novolac type epoxy resin, a cresol novolak type epoxy resin, etc. are mentioned, and these may be used alone or in combination of two or more.

The (B) phenol resin used in the present invention refers to monomers, oligomers, and polymers generally having two or more phenolic hydroxyl groups in one molecule, and is not particularly limited. For example, dicyclopentadiene-modified phenol resin , Phenol aralkyl resin, naphthol aralkyl resin, phenol novolak resin, cresol novolak resin, terpene-modified phenol resin, triphenolmethane type resin, etc., and these may be used alone or in combination of two or more. Good.
As a compounding quantity, 0.9 or more and 1.2 or less are preferable by the equivalent ratio of the epoxy group number of all the epoxy resins, and the phenolic hydroxyl group number of all the phenol resins.

  As the (C) curing accelerator used in the present invention, any curing accelerator may be used as long as it accelerates the curing reaction between an epoxy group and a phenolic hydroxyl group, and those generally used for sealing materials can be widely used. Examples include 1,8-diazabicyclo (5,4,0) undecene-7, 2-methylimidazole, triphenylphosphine, tetraphenylphosphonium / tetraphenylborate salts, and the like, but are not limited thereto. A hardening accelerator may be used individually by 1 type, or may use 2 or more types together.

The (D) inorganic filler used in the present invention is not particularly limited. For example, fused silica, spherical silica, crystalline silica, secondary agglomerated silica, porous silica, secondary agglomerated silica or porous silica is used. Examples thereof include pulverized silica, alumina, silicon nitride and the like, and these may be used alone or in combination of two or more. In particular, fused silica and crystalline silica are preferable. The shape of the inorganic filler may be crushed or spherical, but spherical fused silica is preferred from the viewpoint of the balance of flow characteristics, mechanical strength, and thermal characteristics. Furthermore, it is possible to use a surface-treated one with a coupling agent or the like.
The blending amount of the inorganic filler is preferably 70% by weight or more and 95% by weight or less in the total epoxy resin composition from the balance between moldability and reliability.

The activated alumina (E) used in the present invention has a porous structure having a large specific surface area exceeding 100 m ² / g, and can adsorb inorganic ions, water, and low molecular organic compounds on this extremely large surface. Therefore, it acts as an ion scavenger. By adding the activated alumina, the ionic impurities in the cured product of the epoxy resin composition are adsorbed on the activated alumina, so that the moisture resistance reliability and the high temperature storage stability are improved. From the viewpoints of adsorption capacity of ionic impurities, moisture resistance reliability as an epoxy resin composition, high temperature storage stability and fluidity balance, among the above activated alumina, the average specific surface area is 30 m ² / g or more, 400 m. More preferred is porous alumina that is ² / g or less.
The blending amount of the activated alumina (E) of the present invention is preferably 0.01% by weight or more and 5% by weight or less, more preferably 0.05% by weight or more and 4% by weight or less in the total epoxy resin composition. Below the lower limit, the ion trapping effect is small, and the improvement effect of moisture resistance reliability may be insufficient. When the above upper limit is exceeded, the moisture absorption rate increases and the solder crack resistance may be lowered. An ion scavenger other than activated alumina may be used in combination as long as moisture resistance reliability and high-temperature storage stability can be maintained.

  The epoxy resin composition of the present invention includes components (A) to (E), a coupling agent such as a silane coupling agent, a colorant such as carbon black and bengara, a natural wax, a synthetic wax, etc. Various additives such as mold release agents, flame retardants such as aluminum hydroxide, magnesium hydroxide, zinc borate, zinc molybdate, and phosphazene, low-stress additives such as silicone oil and rubber, etc., may be added as appropriate. .

  In the epoxy resin composition of the present invention, the components (A) to (E) and other additives are sufficiently uniformly mixed at room temperature using a mixer or the like, and then melt-kneaded with a hot roll or a kneader. It is obtained by pulverizing after cooling. These epoxy resin compositions can be applied to coating, insulation, sealing, etc. of transistors and integrated circuits that are electrical or electronic components.

  In order to seal an electronic component such as a semiconductor element and manufacture a semiconductor device using the epoxy resin composition of the present invention, it may be molded and cured by a molding method such as a transfer mold, a compression mold, or an injection mold.

Examples of the present invention are shown below, but the present invention is not limited thereto. The blending ratio is parts by weight.
The abbreviations and structures of the epoxy resins and phenol resins used in the examples and comparative examples, and the contents of the ion scavenger are summarized below.
Epoxy resin (E-1): Orthocresol novolak type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., EOCN1020, softening point 55 ° C., epoxy equivalent 196)
Epoxy resin (E-2): biphenyl type epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd., YX-4000, epoxy equivalent 190, melting point 105 ° C.)
Phenol resin (H-1): Phenol novolak resin (manufactured by Sumitomo Bakelite Co., Ltd., PR-HF-3 softening point 80 ° C., hydroxyl group equivalent 104)
Phenol resin (H-2): Phenol aralkyl resin (Mitsui Chemicals, XLC-4L, hydroxyl equivalent 168, softening point 62 ° C.)
Ion scavenger (IC-1): activated alumina (average particle size 21.5 μm, specific surface area 260 m ² / g, (ALCAN CHEMICALS, AA-101)
Ion scavenger (IC-2): BiO _1.0 (OH) _0.7 (NO ₃ ) _0.3 (Bi-based inorganic compound, manufactured by Toagosei Co., Ltd., IXE-500)
Ion scavenger (IC-3): Hydrotalcite compound (Kyowa Chemical Industry Co., Ltd., DHT-4H)

Example 1
Epoxy resin (E-1) 12.76 parts by weight Phenolic resin (H-1) 6.69 parts by weight Triphenylphosphine (hereinafter referred to as TPP) 0.40 part by weight Fused spherical silica (average particle size 26.5 μm) 65 0.000 parts by weight Ion scavenger (IC-1) 3.50 parts by weight γ-glycidoxypropyltrimethoxysilane (hereinafter referred to as epoxysilane)
0.20 parts by weight Carbon black 0.30 parts by weight Carnauba wax 0.40 parts by weight Aluminum hydroxide (average particle size 4.3 μm) 10.00 parts by weight was mixed at room temperature using a mixer at 70 to 100 ° C. Roll kneading, cooling and pulverizing gave an epoxy resin composition. The obtained epoxy resin composition was evaluated by the following methods. The results are shown in Table 1.

  Moisture absorption: Using a low-pressure transfer molding machine, a disk-shaped test piece having a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, a curing time of 120 seconds and a diameter of 50 mm and a thickness of 3 mm was molded. Heat treatment was performed at 175 ° C. for 8 hours as a post cure. The weight before moisture absorption treatment of the test piece and the weight after humidification treatment for 168 hours in an environment of 85 ° C. and 85% relative humidity were measured, and the moisture absorption rate of the test piece was shown as a percentage. The unit is% by weight.

  Solder resistance: 80 pQFP (thickness 2.0 mm, chip size 6.0 mm × 6.0 mm) is molded using a low-pressure transfer molding machine at a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 120 seconds. did. Six packages heat treated at 175 ° C. for 8 hours as post-cure were humidified for 168 hours in an environment of 85 ° C. and 60% relative humidity, and then IR reflow treatment (220 ° C.) was performed. The presence or absence of internal peeling or cracks after the treatment was observed with an ultrasonic flaw detector, and the number of defective packages was counted. When the number of defective packages is n, n / 6 is displayed.

  High-temperature storage characteristics: Using a low-pressure transfer molding machine, 16 pDIP (chip size 3.0 mm × 3.5 mm) was molded at a molding temperature of 175 ° C., a pressure of 6.9 MPa, and a curing time of 120 seconds. After the heat treatment for 8 hours, a high temperature storage test (185 ° C., 1000 hours) was performed, and a package in which the electrical resistance value between the wirings increased by 20% with respect to the initial value was determined to be defective. The number of defects in 15 packages is shown.

Moisture resistance reliability: Using a low-pressure transfer molding machine, 16 pDIP (chip size: 3.0 mm × 3.5 mm) was molded at a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 120 seconds. After heat treatment at 8 ° C. for 8 hours, a pressure cooker test (125 ° C., pressure 2.2 × 10 ⁵ Pa, 500 hours) was performed to measure circuit open defects. The number of defects in 15 packages is shown.

Examples 2-6, Comparative Examples 1-6
Blended according to Tables 1 and 2, 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 Tables 1 and 2.

  A semiconductor device obtained by encapsulating a semiconductor element using the epoxy resin composition of the present invention has excellent moisture resistance reliability and high-temperature storage properties. Therefore, it can be suitably used for a semiconductor device that requires reliability, particularly for a semiconductor device that is used for outdoor equipment such as a vehicle.

Claims (3)

(A) epoxy resin, (B) phenol resin, (C) curing accelerator, (D) inorganic filler, and (E) activated alumina as essential components, and the content of (E) activated alumina is all epoxy An epoxy resin composition for encapsulating a semiconductor, wherein the content is 0.01 wt% or more and 5 wt% or less in the resin composition. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the (E) activated alumina is porous alumina having an average specific surface area of 30 m ² / g or more and 400 m ² / g or less. A semiconductor device obtained by sealing a semiconductor element using the epoxy resin composition for semiconductor sealing according to claim 1.