JP2001329144A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition for sealing a semiconductor excellent in moldability, flame retardancy, characteristics in high-temperature preservation, moisture proof reliability and solder crack resistance without containing a halogen-based flame retardant and an antimony compound. SOLUTION: This epoxy resin composition for sealing the semiconductor is characterized in that the composition consists essentially of (A) an epoxy resin, (B) a phenol resin, (C) a curing accelerator, (D) an inorganic filler, (E) a phosphazene compound and (F) zinc borate (2ZnO.3B2O3.3.5H2).

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 need for an epoxy resin composition that can achieve a flame retardant grade V-0 without using a halogen-based flame retardant such as a bromine-containing organic compound and an antimony compound such as antimony oxide as a 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. In addition, zinc borate has been proposed as a flame retardant, and by adding a large amount thereof, a flame retardant grade V-0 can be achieved, and there is no problem in high-temperature storage characteristics. There is a problem that solder crack resistance is reduced. As a technique to improve the above disadvantages,
Solves flame retardancy and moisture resistance reliability 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 Although proposals have been made (JP-A-10-251486, JP-A-11-11945, etc.), a large amount of addition is required in order to develop sufficient flame retardancy. There is a problem that causes deterioration of cracking property. Furthermore, although proposals have been reported to solve flame retardancy and high-temperature storage properties by using a cyclic phosphazene compound alone as a flame retardant (Japanese Patent Application Laid-Open No. 10-259292), it is difficult to achieve both reliability and moldability. That is, maintaining flame retardancy,
An epoxy resin composition which 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 has been demanded.

[0004]

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.

[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) zinc borate represented by the general formula (1) as essential components, and using the same. The semiconductor device is characterized in that the semiconductor element is sealed with the semiconductor device. _{pZnO · qB 2 O 3 · rH} 2 O (1) (p, q, r 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, diphenylene 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, diphenylene skeleton, and the like), naphthol aralkyl resins, and the like, may be used alone or in combination.
In particular, phenol novolak resin, dicyclopentadiene-modified phenol resin, terpene-modified phenol resin,
Phenol aralkyl resins, naphthol aralkyl resins and the like are preferred. 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, 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 maximum particle size of the inorganic filler is preferably 74 μm or less. The average particle size is preferably 5 to 25 μm.
Further, by mixing particles having different particle sizes, the filling amount can be increased. As the inorganic filler, a material which has been surface-treated with a silane coupling agent in advance may be used. The amount of the inorganic filler in the total epoxy resin composition is preferably 6% in view of the balance between moldability and solder crack resistance.
It is preferably contained in an amount of 0 to 95% by weight. 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 are caused, 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 general formula (3) can be exemplified, and acts as a flame retardant.

Embedded image In the general 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. , A mercapto group, a hydroxy group, a fluoroalkyl group and the like, and 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 general formula (2)

Embedded image (In the formula, n is an integer of 3 to 7, R represents the same or different organic group.) R in the general formula (2) is an alkyl group, an alkenyl group, an alkoxy group, an aryl group, Although an aryloxy group and the like are common, as represented by an amino group, a mercapto group, a hydroxy group and a fluoroalkyl group,
It may contain N, S, O, F atoms 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 general formula (2) include, for example, hexapropylcyclotriphosphazene, tetraethoxydipropoxycyclotriphosphazene, hexaphenoxycyclotriphosphazene, hexaanilinocyclotriphosphazene, hexakis (3 -Mercaptopropyl) cyclotriphosphazene, hexakis (heptafluoropropyloxy) cyclotriphosphazene and the like are mentioned as examples. R in the general formulas (3) and (2) is preferably an aryloxy group from the viewpoint of heat resistance and moisture resistance, and from the viewpoint of compatibility with the epoxy resin and fluidity of the epoxy resin composition, At least n among 2n Rs
More preferably, each is a phenoxy group.

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 general formula (2) is bonded to a part of R of another cyclic phosphazene via another organic group or R, These other organic groups may be not only single groups but also groups combined with other groups. 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,
An organic group such as 1,6-dioxyhexane or the like obtained by removing a hydrogen atom from a hydroxyl group of a diol compound, or a hydrogen atom from a dihydroxy compound such as a bifunctional phenol compound such as hydroquinone, 4,4′-biphenol or bisphenol F. Excluded groups and the like 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 zinc borate represented by the general formula (1) used in the present invention acts as a flame retardant similarly to the phosphazene compound. Zinc borate represented by the general formula (1) is 2ZnO.3B ₂ O ₃ because of the balance between flame retardancy and moisture resistance reliability.
· 3.5 H ₂ O and _{4ZnO · B 2 O 3 · H} 2 O and the like, in _{particular, 2ZnO · 3B 2 O 3 ·} 3.5H 2 O exhibits a high flame retardancy. The amount of zinc borate is preferably from 1 to 20% 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 20% by weight, the moisture resistance reliability and the moldability are undesirably reduced. The average particle size is 1 to 30 μm, more preferably 5 to 20 μm.

[0015] The phosphazene compound and zinc borate each have the property of imparting flame retardancy even when used alone. However, a large amount of the phosphazene compound and zinc borate are required to exhibit sufficient flame retardancy. When 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. By using a phosphazene compound and zinc borate in combination, the flame retardancy is further improved as a synergistic effect, and the blending amount can be reduced. The phosphazene compound inhibits a combustion reaction by forming a polyphosphoric acid layer and a carbonized layer during combustion. Zinc borate has the effect of improving the strength of the carbonized layer by forming a glassy film. Although the reason is not clear, by using both of them, their abilities can be complemented and a high flame retardancy can be obtained as a synergistic effect. As a result,
Even if the compounding amount is reduced, flame retardancy can be maintained, 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 content of bromine atoms can be measured by elemental analysis such as fluorescent X-ray analysis and ion chromatography. The content of antimony atoms can be measured by elemental analysis such as atomic absorption analysis, emission analysis, X-ray fluorescence spectroscopy, and ion chromatography.

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 semiconductors are encapsulated by using the epoxy resin composition of the present invention, and semiconductor devices are manufactured by hardening and molding by conventional molding methods such as transfer molding, compression molding, and injection molding. I just need.

[0018]

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 of phenolic resins are summarized below. Epoxy resin (E-1): biphenyl type epoxy resin [4,4'-bis (2,3-epoxypropoxy)-
3,3 ′, 5,5′-tetramethylbiphenyl is a main component. Epoxy equivalent 190 g / eq, melting point 105
° C], epoxy resin (E-2): dicyclopentadiene-modified phenolic epoxy resin (epoxy equivalent: 265 g / e
q, softening point 60 ° C), phenolic resin (H-1): phenol aralkyl resin (hydroxyl equivalent 165 g / eq, softening point 62 ° C), phenolic resin (H-2): phenol novolak resin (hydroxyl equivalent 104 g / eq, Softening point 80 ° C)

Example 1 Epoxy resin (E-1) 7.7 parts by weight Phenol resin (H-1) 6.8 parts by weight 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) 0.2 part by weight fused spherical silica 76.0 parts by weight Cyclic phosphazene compound represented by formula (4) 3.0 parts by weight

Embedded image Zinc borate (2ZnO.3B ₂ O ₃ .3.5H ₂ O, average particle size 10 μm) 5.0 parts by weight Epoxysilane coupling agent 0.5 parts by weight Carbon black 0.3 parts by weight Carnauba wax 0.5 parts by weight At room temperature using a supermixer, 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: 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 higher the value, the faster the curing. The unit is N · m. Flame retardancy: molding temperature 1 using low pressure transfer molding machine
A test piece (127 mm × 12.7 mm × 3.2 mm) was molded at 75 ° C., a pressure of 70 kg / cm ² and a curing time of 120 seconds, and after-baked at 175 ° C. for 8 hours, followed by the UL-94 vertical method. Measure F and Fmax,
Flame retardancy was determined. Hot strength: A test piece (80 mm × 10 mm × 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, and treated as an after-bake at 175 ° C. for 8 hours. Later, 240
The flexural strength at ° C. was measured according to JIS K 6911. The unit is N / mm ² . Water absorption: molding temperature 1 using low pressure transfer molding machine
A test disk (diameter 50 mm, thickness 4 mm) was molded at 75 ° C., pressure 70 kg / cm ² , and curing time 120 seconds, and treated at 175 ° C. for 8 hours as an after-bake, then 150 ° C.
For 16 hours and a water absorption treatment at 85 ° C. and a relative humidity of 85% for 168 hours, the percentage of the increase in weight relative to the initial weight was determined. Units%. Solder crack resistance: Using low pressure transfer molding machine
Molding temperature 175 ° C, pressure 70kg / cm ² , curing time 1
In 20 seconds, 80 pQFP (2 mm thick, chip size 9.
0 mm × 9.0 mm), and after-baking at 175 ° C. for 8 hours, 85 ° C. and 85% relative humidity
96 hours of processing, and IR reflow processing (240
C., 10 seconds). The processed package was observed for defects such as peeling and cracks inside the package using an ultrasonic flaw detector. 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 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%. Bromine atom, antimony atom content: pressure 60 kg / cm
^The resulting mixture was compression-molded to a diameter of 40 mm and a thickness of 5 to 7 mm in ² , and the content of bromine atoms and antimony atoms in all the epoxy resin compositions was quantified using a fluorescent X-ray analyzer. The unit is% by weight.

Examples 2 to 5, Comparative Examples 1 to 3 Epoxy resin compositions were prepared 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. In Example 5, the cyclic phosphazene compound represented by the formula (5) was used.

Embedded image

The brominated bisphenol A used in Comparative Example 3
The epoxy equivalent of the epoxy resin is 365 g / eq. .

[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 and an antimony compound and has excellent moldability can be obtained. Excellent high temperature storage characteristics, moisture resistance reliability and solder crack resistance.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08K 3/38 C08K 3/38 5/5399 5/5399 H01L 23/29 B29K 61:04 23/31 63: 00 // B29K 61:04 105: 16 63:00 B29L 31:34 105: 16 H01L 23/30 R B29L 31:34 F term (reference) 4F206 AA37 AA39 AB03 AB11 AB16 AB19 AD03 AG01 AG03 AH37 JA02 JB17 JF01 JF02 JF05 JL02 4J002 CD041 CD051 CD061 CD071 CD181 DE146 DJ006 DJ016 DK008 EW157 FD016 FD137 FD138 GQ00 4J036 AB16 AC02 AD07 AD08 AD10 AE05 AF06 AF07 CB08 DC41 DC46 DD07 FA05 FA06 FA12 FB06 FB07 JA07 4M109 AA01 EB12 EB03 EB07 EB02 EC01 EC03 EC14 EC20

Claims (7)

[Claims] 1. An epoxy resin (A), a phenolic resin (B), a curing accelerator (C), an inorganic filler (D), a phosphazene compound (E), and (F) boric acid represented by the general formula (1). An epoxy resin composition for encapsulating a semiconductor, comprising zinc as an essential component. _{pZnO · qB 2 O 3 · rH} 2 O (1) (p, q, r is a positive number) 2. Zinc borate is 2ZnO.3B ₂ O _3.
3.5 H 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 general 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 out of 2n Rs in the cyclic phosphazene compound represented by the general formula (2) are phenoxy groups. 6. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein bromine atoms and antimony atoms in the total epoxy resin composition are each less than 0.1% by weight. 7. A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition for semiconductor encapsulation according to claim 1.