JP2001354839A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition for sealing semiconductors excellent in moidability, flame retardance, high-temperature storage characteristics, moisture resistant reliability and solder crack resistance without containing a halogen-based flame retardant and an antimony compound. SOLUTION: This epoxy resin composition for sealing the semiconductors is characterized as comprising (A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator, (D) an inorganic filler, (E) a phosphazene compound and (F) a compound represented by the general formula (1) MgaAlb(OH)2a+3b-2c(CO3)c.dH2O (1) (wherein, 0<b/a<=1; 0<=c/b<1.5; and d is a positive number) as essential components.

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 flame retardancy and moldability, 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.

[0003] As described above, the corrosion resistance of the bonding portion (bonding pad portion) of a semiconductor element after storing a semiconductor device at a high temperature (for example, 185 ° C or the like) is called high-temperature storage characteristics. As a method for improving the characteristics, a method using diantimony pentoxide (Japanese Patent Laid-Open No.
146950) and a method of combining antimony oxide with an organic phosphine (Japanese Patent Application Laid-Open No. 61-53321) have been proposed and their effects have been confirmed. On the other hand, some types of epoxy resin compositions are not satisfactory. Further, it has been proposed to use a specific phosphazene compound as a flame retardant to solve the reliability such as flame retardancy and high-temperature storage characteristics (JP-A-10-25).
No. 9292), in order to exhibit sufficient flame retardancy, a large amount of addition is required. Therefore, a decrease in moldability due to a decrease in curability, an increase in water absorption, and a decrease in solder crack resistance due to a decrease in strength are required. There is a problem of causing such a problem, and the moisture resistance reliability cannot be said to be sufficient. 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.

[0004]

DISCLOSURE OF THE INVENTION The present invention does not include a halogen-based flame retardant and an antimony compound, and has flame retardancy, moldability,
An object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation excellent in high-temperature storage characteristics, humidity resistance, and solder crack resistance, and a semiconductor device using the same.

[0005]

The present invention provides (A) an epoxy resin, (B) a phenolic resin, (C) a curing accelerator,
An epoxy resin composition for semiconductor encapsulation comprising (D) an inorganic filler, (E) a phosphazene compound, and (F) a compound represented by the general formula (1) as essential components. A semiconductor device in which a semiconductor element is sealed. Mg _a Al _b (OH) _{2a + 3b-2c} (CO ₃ ) _c · dH ₂ O (1) (where 0 <b / a ≦ 1, 0 ≦ c / b <1.5, and d is a positive number )

[0006]

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 resins (having a phenylene skeleton, biphenylene skeleton, etc.), naphthol type epoxy resins 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, biphenylene skeleton, etc.), naphthol aralkyl resins, and the like can be used, and these may be used alone or in combination.
Of these, phenol novolak resins, dicyclopentadiene-modified phenol resins, phenol aralkyl resins, naphthol 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, it is preferable to use the fused silica having a high sphericity in its entirety or in combination with partially crushed silica. The average particle size of the inorganic filler is 5 to 3
0 μm, the maximum particle size is preferably 150 μm or less,
Particularly, the average particle diameter is preferably 5 to 20 μm, and the maximum particle diameter is preferably 74 μm or less. Further, by mixing particles having different particle sizes, the filling amount can be increased. The inorganic filler is
A material which has been surface-treated with a silane coupling agent or the like in advance may be used. As the compounding amount of the inorganic filler, the total amount of the ion scavenger of the present invention and the inorganic filler described later is 70 to 93 in the total epoxy resin composition from the balance of moldability and solder crack resistance. % By weight is preferred. 70
If the content is less than 93% by weight, the solder crack resistance decreases with an increase in water absorption. If the content exceeds 93% by weight, wire sweep,
In addition, problems such as moldability such as pad shift occur, which is not preferable.

The phosphazene compound used in the present invention may be any compound having a phosphazene structure in the compound.
For example, a compound having a structure represented by the formula (3) can be exemplified, and acts as a flame retardant.

Embedded image In the formula (3), n is an integer of 3 to 1000, and R is, for example, generally an alkyl group, an alkenyl group, an alkoxy group, an aryl group, an aryloxy group, and the like. As represented by a mercapto group, a hydroxy group, a fluoroalkyl group and the like, it may contain an N, S, O, F atom or the like. These phosphazene compounds may be used alone or as a mixture. The flame retarding mechanism of the phosphazene compound has the effect of promoting carbonization by the contained phosphorus, that is, the effect of protecting the surface of the cured product and blocking oxygen by forming a nonflammable carbonized layer on the surface of the cured product. This is because nitrogen gas is generated at the time of thermal decomposition by the nitrogen contained, and oxygen is shut off even in the gas phase. The phosphazene compound can impart high flame retardancy due to the flame retardant effect working in both the solid phase and the gas phase.

Preferred phosphazene compounds are cyclic phosphazene compounds in view of the fluidity of the epoxy resin composition of the present invention. As the cyclic phosphazene compound, for example, a cyclic phosphazene compound represented by the formula (2)

Embedded image (Wherein n is an integer of 3 to 7, R represents the same or different organic groups), and R in the formula (2) represents an alkyl group, an alkenyl group, an alkoxy group, an aryl group, an aryloxy group. Although the groups are generally used, they may contain N, S, O, F atoms and the like as represented by amino groups, mercapto groups, hydroxy groups, fluoroalkyl groups and the like. These cyclic phosphazene compounds may be used alone or as a mixture. Further, it is more preferable that the main component be a trimer 6-membered ring. Specific examples of the cyclic phosphazene compound represented by the formula (2) include, for example, hexapropylcyclotriphosphazene, tetraethoxydipropoxycyclotriphosphazene, hexaphenoxycyclotriphosphazene, hexaanilinocyclotriphosphazene, hexakis (3- Examples include mercaptopropyl) cyclotriphosphazene and hexakis (heptafluoropropyloxy) cyclotriphosphazene. R in the formulas (3) and (2) is preferably an aryloxy group from the viewpoint of heat resistance and moisture resistance reliability, and 2n from the viewpoint of compatibility with the epoxy resin and fluidity of the epoxy resin composition. More preferably, at least n of the Rs are phenoxy groups.

As an example of another cyclic phosphazene compound, a compound in which one cyclic phosphazene is bonded to another cyclic phosphazene via another organic group in order to enhance flame retardancy is also preferable. In this case, the cyclic phosphazenes may be of the same type or of different types. For example, a compound in which a part of R of one cyclic phosphazene represented by the formula (2) is bonded to a part of R of another cyclic phosphazene via another organic group or R may be used. The other organic group of may be not only a single group but also a group combined with another group. For example, a compound having a phosphazene group at both terminals of an organic group may be used. As another organic group bonding these cyclic phosphazenes to each other, for example, 1,
Organic groups such as 6-dioxyhexane, etc. in which a hydrogen atom has been removed from the hydroxyl group of a diol compound, or 2 such as hydroquinone, 4,4′-biphenol, bisphenol F, etc.
A group obtained by removing a hydrogen atom from a dihydroxy compound such as a functional phenol compound can be preferably used.

The amount of the phosphazene compound of the present invention is
It is preferably 0.01 to 10% by weight, more preferably 0.1 to 5% by weight, based on the total epoxy resin composition. 0.0
If it is less than 1% by weight, the flame retardancy is insufficient, and if it exceeds 10% by weight, the curability, heat resistance and strength are reduced, and the water absorption is undesirably increased.

The compound represented by the general formula (1) used in the present invention has flame retardancy when highly dispersed in an epoxy resin composition. Therefore, the flame retardancy is improved as a synergistic effect with the phosphazene compound. In addition, it is possible to reduce the blending amount. As a result, even if the compounding amount is reduced, the flame retardancy is maintained, and the moldability and strength are reduced, and the water absorption rate is prevented from increasing. Therefore, the moldability, high-temperature storage characteristics, moisture resistance reliability, and solder crack resistance are reduced. The phosphazene compound is more improved than when the phosphazene compound is used alone. Furthermore, particularly preferably, Mg _4.3
Al ₂ (OH) _12.6 CO ₃ · 3.5 H ₂ O. The compounding amount of the compound represented by the general formula (1) of the present invention is preferably 0.2 to 2% by weight in the whole epoxy resin composition.
If it is less than 0.2% by weight, the moisture resistance reliability is insufficient, and if it exceeds 2% by weight, the curability is significantly reduced, the water absorption is increased, and the solder crack resistance is significantly reduced. Further, the total amount of the compound represented by the general formula (1) of the present invention and the above-mentioned inorganic filler is preferably 70 to 93% by weight in the total epoxy resin composition from the balance between moldability and solder crack resistance. preferable. If it is less than 70% by weight, the solder cracking resistance decreases with an increase in water absorption, and if it exceeds 93% by weight,
Problems such as wire sweep and pad shift may occur, which are not preferable. In addition to the compound represented by the general formula (1) of the present invention, other ion scavengers for scavenging phosphoric acid, organic acid anions, halogen anions, alkali metal cations, alkaline earth metal cations and the like may be used in combination. it can. Examples of ion scavengers that can be used in combination include, for example, B
i ₂ O ₃ .nH ₂ O, Zr (HPO ₄ ) ₂ .H ₂ O, Ti (H
PO ₄ ) ₂ .H ₂ O, (NH ₄ ) ₃ Mo ₁₂ (PO ₄ ) ₄₀ .nH
₂ O, Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ , BiO (OH) _0.7
(NO ₃ ) _0.3 , BiO (OH) _0.74 (NO ₃ ) _0.15 (H
SiO ₃ ) _0.11 , BiO (OH) and the like, and these may be used alone or as a mixture. The amount of the ion scavenger that can be used in combination is preferably 0.1 to 1% by weight of the total epoxy resin composition, and if it exceeds 1% by weight, the curability decreases.

The phosphazene compound and the compound of the general formula (1) each have the property of imparting flame retardancy even when used alone.
In order to develop sufficient flame retardancy, a large amount of compounding is required. However, if it is blended in a large amount, the moldability and strength tend to decrease, and the water absorption tends to increase, 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 the combined use of the phosphazene compound of the present invention and the compound of the general formula (1) further improves the flame retardancy as a synergistic effect and can reduce the amount of the compound. The phosphazene compound of the present invention promotes carbonization of the cured resin component, and the compound of the general formula (1) of the present invention has an endothermic effect at the time of combustion, has a function of trapping flammable gas, and has a flame retardant property. It is thought to contribute to. Furthermore, the general formula (1) of the present invention
The compound has an effect of preventing corrosion of aluminum by trapping ionic impurities contained in the resin component, the phosphazene compound and the like, and improving the moisture resistance reliability. Although the reason is not clear, the combined use of both makes it possible to complement each other's abilities and obtain high flame retardancy as a synergistic effect. 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 epoxy resin composition of the present invention comprises (A)
In addition to the component (F), a flame retardant such as a brominated epoxy resin or antimony trioxide may be contained as necessary, but the stability of the electrical characteristics of the semiconductor device at a high temperature of 150 to 200 ° C. For applications required, the content of bromine atoms and antimony atoms is preferably less than 0.1% by weight in the total epoxy resin composition, and more preferably not completely contained. If either the bromine atom or the antimony atom is 0.1% by weight or more, the resistance value of the semiconductor device will increase with time when left at high temperatures, and eventually the failure of the gold wire of the semiconductor element to break will occur. Can occur. Also, from the viewpoint of environmental protection, it is desirable that the content of each of the bromine atom and the antimony atom is less than 0.1% by weight and that they are not contained as much as possible. The epoxy resin composition of the present invention contains the components (A) to (F) as essential components,
In addition, various additives such as a silane coupling agent, a colorant such as carbon black, a release agent such as a natural wax and a synthetic wax, and various additives such as a low-stress additive such as silicone oil and rubber are appropriately compounded as necessary. No problem.
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 can be sealed using the epoxy resin composition of the present invention. In order to manufacture a semiconductor device, a conventional molding method such as a transfer mold, a compression mold, and an injection mold may be used for curing and molding.

[0017]

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,
Abbreviations and structures of the phenolic resin, the phosphazene compound, and the compound represented by the general formula (1) (ion scavenger) are summarized below. Epoxy resin (E-1): ortho-cresol novolak type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., softening point 62 ° C,
Epoxy equivalent 198), Epoxy resin (E-2): biphenyl type epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd., melting point 95 ° C., epoxy equivalent 191), phenol resin (H-1): phenol novolak resin (softening) point 74 ° C., hydroxyl equivalent 104), phenol resin (H-2): phenol aralkyl resin (softening point 75 ° C., hydroxyl equivalent 175), ion _{scavenger: Mg 4.3 Al 2 (OH)} 12.6 CO 3 · 3.
5H ₂ O (manufactured by Kyowa Chemical Co., Ltd., DHT), cyclic phosphazene compound (P-1),

Embedded image

A cyclic phosphazene compound (P-2),

Embedded image

Cyclic phosphazene compound (P-3)

Embedded image

Example 1 Epoxy resin (E-1) 174 parts by weight Phenol resin (H-1) 91 parts by weight 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) 2 parts by weight Fused spherical silica 700 parts by weight Cyclic phosphazene compound (P-1) 10 parts by weight Ion scavenger 10 parts by weight Epoxysilane coupling agent 5 parts by weight Carbon black 3 parts by weight Carnauba wax 5 parts by weight at room temperature using a super mixer And 70 to 10
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: Measurement was performed 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 higher the value, the faster the curing. The unit is N · m. 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 disk (diameter 50 mm, thickness 4 mm) is 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 treated at 175 ° C. for 8 hours as an after-bake. After that, a drying treatment was carried out at 150 ° C. for 16 hours.
The percentage of the increase in weight with respect to the initial weight was determined for the sample subjected to the water absorption treatment for 68 hours. 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. High-temperature storage characteristics: using a low-pressure transfer molding machine, molding temperature 175 ° C., pressure 70 kg / cm ² , curing time 12
16pDIP in 0 seconds (chip size 3.0mm × 3.5
mm), and after baking at 175 ° C. for 8 hours, a high-temperature storage test (185 ° C., 1000 hours) was performed. A package having an electrical resistance between wirings of 1.2 times the initial value was obtained. It was determined to be defective. The percentage defective in 15 packages is shown as a percentage. Units%. Moisture resistance reliability: Using a low pressure transfer molding machine, molding temperature 175 ° C, pressure 70 kg / cm ² , curing time 120
1 with a simulation device (without passivation film) in seconds
A 6pDIP (chip size: 3.0 mm × 3.5 mm) was molded, treated at 175 ° C. for 8 hours as an after-bake, and then 5.5 V was applied at 130 ° C. and a relative humidity of 85% to measure open circuit failure. It was expressed as the time when half of the packages were defective. In addition,
The evaluation was performed up to 1000 hours. The unit is time. Content of Br atom and Sb atom: Compression molded at a pressure of 60 kg / cm ² to a diameter of 40 mm and a thickness of 5 to 7 mm. The contents of bromine atoms and antimony atoms were quantified. The unit is weight%.

Examples 2 to 6, Comparative Examples 1 to 3 Epoxy resin compositions were obtained in the same manner as in Example 1 according to the formulations in Table 1, and evaluated in the same manner as in Example 1. Table 1 shows the results. Brominated bisphenol A used in Comparative Example 1
The epoxy equivalent of the type epoxy resin is 365.

[Table 1]

[0023]

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

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 23/29 H01L 23/30 R 23/31 F-term (Reference) 4J002 CC04X CC05X CC07X CD04W CD05W CD06W CD07W CD13W CE00X DE147 DE289 DJ007 DJ017 DJ047 EU116 EU136 EW016 EW158 EW176 EY016 FD017 FD138 FD156 GQ05 4J036 AA01 DA02 FA01 FA03 FA12 FB06 FB07 JA07 4M109 AA01 CA21 EA02 EB03 EB04 EB07 EB12 EC20

Claims (7)

[Claims] (A) an epoxy resin, (B) a phenolic resin, (C) a curing accelerator, (D) an inorganic filler, (E) a phosphazene compound, and (F) a compound represented by the general formula (1). An epoxy resin composition for encapsulating a semiconductor, comprising: Mg _a Al _b (OH) _{2a + 3b-2c} (CO ₃ ) _c · dH ₂ O (1) (where 0 <b / a ≦ 1, 0 ≦ c / b <1.5, and d is a positive number ) 2. A compound represented by the general formula (1):
_{4.3 Al 2 (OH) 12 .6} CO 3 · 3.5H 2 O in which claim 1 semiconductor encapsulating epoxy resin composition. 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the phosphazene compound is a cyclic phosphazene compound. 4. The epoxy resin composition for semiconductor encapsulation according to claim 3, wherein the cyclic phosphazene compound is a cyclic phosphazene compound represented by the formula (2). Embedded image (In the formula, n represents an integer of 3 to 7, and R represents the same or different organic groups.) 5. The epoxy resin composition for semiconductor encapsulation according to claim 4, wherein at least n of 2n Rs of the cyclic phosphazene compound represented by the formula (2) are phenoxy groups. 6. The epoxy for semiconductor encapsulation according to claim 1, wherein the total amount of bromine atoms and antimony atoms contained in the total epoxy resin composition is less than 0.1% by weight. Resin composition. 7. A semiconductor device comprising a semiconductor element encapsulated by using the epoxy resin composition for semiconductor encapsulation according to claim 1.