JP2001213943A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition for encapsulating a semiconductor which contains neither a halogenide flame-retardant nor an antimony compound, and is excellent in moldability, flame-retardant property, high temperature storage property, moisture-proof, and soldering crack resistance. SOLUTION: The epoxy resin composition for encapsulating a semiconductor comprises (A) an epoxy resin, (B) a phenol resin, (C) a hardening promoter, (D) an inorganic filler, (E) a metal hydroxide solid solution as represented by general formula (1), and (D) zinc molybdate. Mg1-xM2+x(OH)2 (1) (In the formula, M2+ is at least one bivalent metal ion selected from the group consisting of Mn2+, Fe2+, Co2+, Ni2+, And Zn2+; and x is a number of 0.01<=x<=0.5).

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 which does not contain a halogen-based flame retardant and an antimony compound and has excellent flame retardancy and high-temperature storage characteristics, and a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, electronic components such as diodes, transistors, and integrated circuits are mainly sealed with an epoxy resin composition. These epoxy resin compositions contain a halogen-based flame retardant and an antimony compound in order to impart flame retardancy. However, development of an epoxy resin composition having excellent flame retardancy without using a halogen-based flame retardant and an antimony compound is demanded from the viewpoint of environment and hygiene. Further, when a semiconductor device sealed with an epoxy resin composition containing a halogen-based flame retardant and an antimony compound is stored at a high temperature, a thermally decomposed halide is liberated from these flame retardant components and the semiconductor element is bonded. Is known to corrode the semiconductor device and impair the reliability of the semiconductor device.
There is a demand for an epoxy resin composition that can achieve a flame retardant grade of V-0 of UL-94 without using a halogen-based flame retardant and an antimony compound as the flame retardant. As described above, the junction portion (bonding pad portion) of the semiconductor element after storing the semiconductor device at a high temperature (for example, 185 ° C.).
The high-temperature storage characteristics are referred to as the high-temperature storage characteristics. Examples of a method for improving the high-temperature storage characteristics include a method using diantimony pentoxide (Japanese Patent Laid-Open No. 55-146950) and a method using antimony oxide and organic phosphine. (Japanese Patent Application Laid-Open No. 61-53321) and the like have been proposed and their effects have been confirmed. However, with respect to the recent high level of high-temperature storage characteristics required for semiconductor devices, depending on the type of epoxy resin composition, Some are unsatisfactory. In addition, zinc molybdate has been proposed as a flame retardant. Flame retardant grade V-0 can be achieved by adding a large amount thereof, and there is no problem with high-temperature storage characteristics.
There is a problem that moldability and solder crack resistance are reduced. As a technique for improving the above-mentioned drawbacks, flame retardancy is achieved by using a combination of a specific metal hydroxide and a specific metal oxide, or using a composite metal hydroxide of a specific metal hydroxide and a specific metal oxide. There have been proposals to solve the problems of the reliability and the moisture resistance (Japanese Patent Application Laid-Open Nos. Hei 10-251486 and Hei 11
In order to exhibit sufficient flame retardancy, a large amount of addition is required, and there is a problem that the moldability and the solder crack resistance are deteriorated. That is, there is a need for an epoxy resin composition that maintains flame retardancy, is excellent in moldability, high-temperature storage characteristics, moisture resistance reliability, and solder crack resistance, and does not use a halogen-based flame retardant and an antimony compound.

[0003]

SUMMARY OF THE INVENTION The present invention is directed to a semiconductor encapsulation which does not contain a halogen-based flame retardant and an antimony compound and has excellent moldability, flame retardancy, high-temperature storage characteristics, moisture resistance reliability and solder crack resistance. An epoxy resin composition and a semiconductor device obtained by encapsulating a semiconductor element using the same are provided.

[0004]

The present invention provides (A) an epoxy resin, (B) a phenolic resin, (C) a curing accelerator,
It contains (D) an inorganic filler, (E) a metal hydroxide solid solution represented by the general formula (1), and (F) zinc molybdate as essential components, and contains Mg _1-x M ²⁺ _x (OH) ₂ (1 ( ^Where M ²⁺ is Mn ²⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ , Cu
^Represents at least one type of divalent metal ion selected from the group consisting of ²⁺ and Zn ²⁺ , and x represents a number satisfying 0.01 ≦ x ≦ 0.5) More preferably, in general formula (1) The semiconductor encapsulation wherein M ^{2+ of the} metal hydroxide solid solution shown is Zn ²⁺ or Ni ²⁺ , and a part or all of the inorganic filler is coated with (F) zinc molybdate. An epoxy resin composition for use and a semiconductor device obtained by sealing a semiconductor element using the same.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin used in the present invention refers to all monomers, oligomers and polymers having two or more epoxy groups in one molecule, and their molecular weight and molecular structure are not particularly limited. For example, biphenyl type epoxy resin, bisphenol type epoxy resin,
Stilbene epoxy resin, phenol novolak epoxy resin, cresol novolak epoxy resin, triphenolmethane epoxy resin, alkyl-modified triphenolmethane epoxy resin, epoxy resin containing triazine nucleus, dicyclopentadiene-modified phenol epoxy resin, phenol aralkyl Type epoxy resin (having a phenylene skeleton, a diphenylene skeleton and the like) and the like, and these may be used alone or in combination.

The phenolic resin used in the present invention includes:
Monomers, oligomers, and polymers generally having two or more phenolic hydroxyl groups in one molecule are not particularly limited in molecular weight and molecular structure. For example, phenol novolak resin, cresol novolak resin, dicyclopentadiene-modified phenol Resins, terpene-modified phenolic resins, triphenolmethane-type resins, phenol aralkyl resins (having a phenylene skeleton, diphenylene skeleton, and the like) and the like can be used alone or in combination. Of these, phenol novolak resins, dicyclopentadiene-modified phenol resins, phenol aralkyl resins, terpene-modified phenol resins, and the like are particularly preferable. The ratio of the number of epoxy groups in all epoxy resins to the number of phenolic hydroxyl groups in all phenolic resins is preferably 0.8 to 1.3.

As the curing accelerator used in the present invention, any one can be used as long as it promotes a curing reaction between an epoxy group and a phenolic hydroxyl group, and those generally used for a sealing material can be used. For example, 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, 2-methylimidazole, tetraphenylphosphonium / tetraphenylborate and the like can be mentioned, and these may be used alone or as a mixture. Absent.

As the inorganic filler used in the present invention, those generally used for a sealing material can be used. For example, fused silica, crystalline silica, talc, alumina, silicon nitride and the like can be mentioned, and these may be used alone or in combination. Of these, fused spherical silica is particularly preferred in terms of ease of handling and cost. As the blending amount of the inorganic filler, the total amount of the inorganic filler, the metal hydroxide solid solution, the zinc molybdate, and the inorganic material used as a core material of the zinc molybdate described below is determined by the moldability and solder resistance. From the viewpoint of the balance of the cracking property, it is preferable to contain 60 to 95% by weight in the whole epoxy resin composition. If it is less than 60% by weight, the solder cracking resistance decreases with an increase in water absorption, and if it exceeds 95% by weight, problems such as wire sweep and pad shift may arise,
Not preferred.

The metal hydroxide solid solution represented by the general formula (1) used in the present invention acts as a flame retardant. Its flame retarding mechanism is that the metal hydroxide solid solution starts dehydration and absorbs heat during combustion. This inhibits the combustion reaction. In addition, it is considered that the flame retardant layer that promotes carbonization of the cured resin component and blocks oxygen on the surface of the cured product is formed. Further, the metal hydroxide solid solution of the present invention has an effect of appropriately lowering the endothermic onset temperature and improving the flame retardancy. If the endothermic start temperature is low, the moldability and reliability are adversely affected, and if the endothermic start temperature is higher than the decomposition temperature of the resin component, the flame retardancy decreases, but the endothermic start temperature of the metal hydroxide solid solution of the present invention is reduced. Is an appropriate value around 300 to 350 ° C. Of these, particularly preferred M ²⁺ are Ni ²⁺ and Zn ²⁺ . The compounding amount of the metal hydroxide solid solution of the present invention is preferably from 1 to 15% by weight, more preferably from 1 to 10% by weight, based on the whole epoxy resin composition. If it is less than 1% by weight, the flame retardancy is insufficient, and if it exceeds 15% by weight, the solder crack resistance and the moldability are undesirably reduced. The average particle size of the metal hydroxide solid solution of the present invention is 0.5 to 30 μm.
And more preferably 0.5 to 10 μm.
The maximum particle size of the metal hydroxide solid solution of the present invention is 75
μm or less, more preferably 55 μm or less.

The zinc molybdate used in the present invention acts as a flame retardant, like the metal hydroxide solid solution. It is considered that as the flame retardant mechanism, zinc molybdate promotes carbonization of the cured resin component during combustion, shuts off oxygen in the air, stops combustion, and achieves flame retardancy.
Further, zinc molybdate tends to absorb moisture easily, and if the amount is too large, the water absorption of the semiconductor device is increased, and the moisture resistance reliability may be reduced, and the moldability may be reduced.
Therefore, as a core material, for example, transition metal, alumina clay, zinc oxide, calcium carbonate, aluminum nitride,
It is preferable to use one obtained by coating an inorganic substance such as aluminum silicate, magnesium silicate, or the above-mentioned inorganic filler with zinc molybdate. As the core material, the above-mentioned inorganic filler is particularly preferable, and fused spherical silica is most preferable from the viewpoint of easy handling and cost. By coating the core material, only the zinc molybdate on the surface acts as a flame retardant, and it is not necessary to mix a large amount of zinc molybdate, so that the increase in water absorption is suppressed and the moldability is improved. Can be.

The amount of the zinc molybdate coated on the core material is preferably 5 to 40% by weight. The average particle size of the core material coated with zinc molybdate is 0.5
-30 μm, and the maximum particle size is preferably 75 μm or less. The amount of zinc molybdate in the total epoxy resin composition is preferably 0.05 to 5% by weight, more preferably 0.1 to 3% by weight. If it is less than 0.05% by weight, flame retardancy cannot be obtained, and if it exceeds 5% by weight, ionic impurities in the resin composition increase, and the moisture resistance reliability in a pressure cooker test or the like decreases, and the moldability also decreases Is not preferred. The core material of the present invention coated with zinc molybdate can be obtained, for example, as follows. A slurry is prepared by mixing molybdenum oxide and a core material (fused spherical silica or the like) in water, heated to 70 ° C., and a slurry of zinc oxide is slowly mixed with the slurry and stirred for about one hour. The solid is taken out by filtration, and after removing water at 110 ° C., it is pulverized. Thereafter, it is obtained by firing at 550 ° C. for 8 hours.

The metal hydroxide solid solution and zinc molybdate alone have the property of imparting flame retardancy, but a large amount is required to exhibit sufficient flame retardancy. However, when blended in a large amount, the moldability and strength decrease,
It tends to cause an increase in the water absorption rate, and the solder crack resistance decreases. In order to prevent these physical properties from deteriorating, it is necessary to reduce the compounding amount as much as possible. The present inventor has found that by using a metal hydroxide solid solution and zinc molybdate in combination, flame retardancy can be further improved as a synergistic effect, and the blending amount can be reduced. Each flame retardant promotes the carbonization of the cured resin component during combustion, and the metal hydroxide solid solution has an endothermic effect at the time of combustion, and by using both of them, obtains high flame retardancy as a synergistic effect Can be. As a result, flame retardancy can be maintained even if the blending amount is reduced, and a decrease in moldability and strength, an increase in water absorption, and the like can be prevented. The mixing ratio of the metal hydroxide solid solution and zinc molybdate is (metal hydroxide solid solution) /
The weight ratio of (zinc molybdate) is preferably 50/1 to 3/1. If it is out of this range, it is possible to obtain a flame-retardant effect almost alone, and a large amount of compounding is required, which is not preferable.

The epoxy resin composition of the present invention comprises (A)
The component (F) is an essential component, but if necessary, a silane coupling agent, a coloring agent such as carbon black, a release agent such as natural wax and synthetic wax, and a low stress such as silicone oil and rubber. Various additives such as additives may be appropriately compounded. In addition, the epoxy resin composition of the present invention is prepared by mixing the components (A) to (F) and other additives sufficiently and uniformly using a mixer or the like, and then melt-kneading with a hot roll or a kneader. , After cooling and pulverized. Various electronic components such as semiconductor elements are encapsulated using the epoxy resin composition of the present invention, and semiconductor devices are manufactured by curing and molding using conventional molding methods such as transfer molding, compression molding, and injection molding. do it.

[0014]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited to these examples. The mixing ratio is by weight. In addition, the epoxy resin used in the Examples and Comparative Examples,
The abbreviations and structures of the phenolic resins are summarized below. Epoxy resin (E-1): an epoxy resin having a structure represented by the formula (E-1) as a main component (an epoxy equivalent of 185)
g / eq)

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Epoxy resin (E-2): an epoxy resin represented by the formula (E-2) (epoxy equivalent: 200 g / eq)

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Phenol resin (H-1): Formula (H-1)
Phenolic resin (hydroxyl equivalent 170 g / e)
q)

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Phenol resin (H-2): Formula (H-2)
Phenolic resin (hydroxyl equivalent 105 g / e)
q)

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Example 1 77 parts by weight of epoxy resin (E-1) 70 parts by weight of phenol resin (H-1) 2 parts by weight of 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) Fused spherical silica 780 parts by weight Metal hydroxide solid solution (Mg _0.8 Zn _0.2 (OH) ₂ , average particle diameter 1 μm) 30 parts by weight Flame retardant A (average particle diameter 16 μm, specific surface area 1.9 m ² / g) Coated with 2 parts by weight of zinc molybdate per 8 parts by weight. Average particle size of flame retardant A 22 μm, maximum particle size 68 μm.) 30 parts by weight Epoxysilane coupling agent 5 parts by weight Carbon black 2 parts by weight Carnauba Mix 4 parts by weight of wax at room temperature using a super mixer, and mix
Roll kneading was performed at 0 ° C., followed by cooling and pulverization to obtain an epoxy resin composition. The obtained epoxy resin composition was evaluated by the following method. Table 1 shows the results.

Evaluation method Spiral flow: Spiral flow was measured using a mold for measuring spiral flow according to EMMI-1-66 at a mold temperature of 175 ° C., a pressure of 70 kg / cm ² and a curing time of 120 seconds. Curability: Using a JSR Curastometer IVPS manufactured by Orientec Co., Ltd., the diameter of the die was 35 mm, the amplitude angle was 1 °, the molding temperature was 175 ° C., and the torque value after 90 seconds from the start of molding was measured. The smaller the value, the slower the curing. The unit is kgf · cm. Flame retardancy: A test piece (127 mm × 12.7 mm × 3.2 mm) was molded using a low pressure transfer molding machine at a molding temperature of 175 ° C., a pressure of 70 kg / cm ² and a curing time of 120 seconds, and 175 ° C. as an after-bake. , After treatment for 8 hours, ΔF and Fmax were measured according to the UL-94 vertical method,
Flame retardancy was determined. Water absorption: A test disk (diameter 50 mm, thickness 4 mm) was molded using a low-pressure transfer molding machine at a molding temperature of 175 ° C., a pressure of 70 kg / cm ² , and a curing time of 120 seconds. After that, 150
Dry at 16 ° C for 16 hours, 85 ° C, 85% relative humidity
168 hours, the percentage of increase in weight relative to the initial weight was determined. Units%. Solder crack resistance: 80 pQFP (2 mm thick, chip size 9.0 mm × 9.0 mm) was molded using a low pressure transfer molding machine at a molding temperature of 175 ° C., a pressure of 70 kg / cm ² , and a curing time of 120 seconds, followed by after-baking. After treatment at 175 ° C for 8 hours, 85 ° C and relative humidity of 8
96 hours processing at 5%, IR reflow processing (24
(0 ° C., 10 seconds). Using an ultrasonic flaw detector, defects such as peeling and cracks inside the package were observed. The number of defective packages in the six packages is shown. Moisture resistance reliability: Using a low pressure transfer molding machine, molding temperature 175 ° C, pressure 70 kg / cm ² , curing time 120
16pDIP in seconds (chip size 3.0mm x 3.5m
m), and after-baking at 175 ° C. for 8 hours, pressure cooker test (125 ° C.,
(100% relative humidity), the open failure of the circuit was measured, and the open failure occurrence time was defined as humidity resistance reliability. The unit is time. High-temperature storage characteristics: using a low-pressure transfer molding machine, molding temperature 175 ° C., pressure 70 kg / cm ² , curing time 120
16pDIP in seconds (chip size 3.0mm x 3.5m
m) was molded and treated as an after-bake at 175 ° C. for 8 hours, followed by a high-temperature storage test (185 ° C., 1000 hours)
The package in which the electric resistance between the wirings increased by 20% from the initial value was determined to be defective. The percentage defective in 15 packages is shown as a percentage. Units%.

Examples 2 to 8, Comparative Examples 1 to 5 Epoxy resin compositions were obtained in the same manner as in Example 1 according to the formulations in Tables 1 and 2, and evaluated in the same manner as in Example 1.
The results are shown in Tables 1 and 2. The flame retardant B of Example 7 was coated with 3 parts by weight of zinc molybdate per 7 parts by weight of fused spherical silica having an average particle size of 16 μm and a specific surface area of 1.9 m ² / g (average particle size of the flame retardant B was 24 μm). , Maximum particle size 74μ
m). In Example 8 and Comparative Example 1, BiO (OH) _0.7 (NO ₃ ) _0.3 was used as an ion scavenger. The epoxy equivalent of the brominated bisphenol A type epoxy resin used in Comparative Example 1 was 365 g / eq. .

[Table 1]

[0021]

[Table 2]

[0022]

According to the present invention, an epoxy resin composition for encapsulating a semiconductor which does not contain a halogen-based flame retardant and an antimony compound and has excellent moldability can be obtained. Excellent high temperature storage characteristics, moisture resistance reliability and solder crack resistance.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 63/00 C08L 63/00 C H01L 23/29 H01L 23/30 R 23/31 F-term (Reference) 4J002 CC04X CC05X CD04W CD05W CD06W CD07W CD13W CE00X DE078 DE098 DE108 DE118 DE147 DE189 DJ007 DJ017 DJ047 EU116 EU136 EW016 EW176 FD017 FD14X FD156 GQ05 4J036 AA01 AB16 AC02 AD07 AD08 AD10 AE05 AE07 AF06 FA08 EA07 AF06 DD08 EB13 EC14 EC20

Claims (6)

[Claims] 1. An epoxy resin, (B) a phenolic resin, (C) a curing accelerator, (D) an inorganic filler, (E) a metal hydroxide solid solution represented by the general formula (1), F)
An epoxy resin composition for encapsulating a semiconductor, comprising zinc molybdate as an essential component. Mg _1-x M ²⁺ _x (OH) ₂ (1) (where M ²⁺ is Mn ²⁺ , Fe ²⁺ , Co ²⁺ , Ni ²⁺ , Cu
^Represents at least one type of divalent metal ion selected from the group consisting of ²⁺ and Zn ²⁺ , and x represents a number satisfying 0.01 ≦ x ≦ 0.5) 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein M ^{2+ of the} metal hydroxide solid solution represented by the general formula (1) is Zn ²⁺ or Ni ²⁺ . 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the component (F) is an inorganic substance coated with zinc molybdate. 4. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein (D) a part or all of the inorganic filler is coated with zinc molybdate. 5. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein (D) the inorganic filler is fused spherical silica. 6. A semiconductor device comprising a semiconductor element encapsulated by using the epoxy resin composition for semiconductor encapsulation according to claim 1.