JP2000086867A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition for sealing a semiconductor compatible with an insertion mounting method and a surface mounting method excellent in ordinary temperature shelf stability, moisture resistance reliability and moldability. SOLUTION: This composition comprises as essential components an epoxy resin, a phenol resin, a tetrasubstituted phosphonium salt of a conjugate base of a compound having at least two phenolic hydroxyl groups in one molecule as a curing accelerator, the electroconductivity of extraction water of which compound being 1,000 μS/cm or less, and an inorganic filler, the equivalent ratio of epoxy groups in all the epoxy resins to the phenolic hydroxyl groups in all the phenol resins being 0.5-2 and the amount of the inorganic filler compounded being 200-2,400 pts.wt. based on 100 pts.wt. of the total amount of all the epoxy resins and all the phenol resins.

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 is excellent in room temperature storage characteristics and humidity resistance and is compatible with insertion mounting and surface mounting, and a semiconductor device using the same.

[0002]

2. Description of the Related Art Epoxy resin compositions for semiconductor encapsulation (hereinafter referred to as resin compositions) have been developed and produced in order to protect the main bodies of diodes, transistors, IC chips and the like from mechanical and chemical actions. . Items required for this resin composition are changing depending on the type of IC chip, the structure of the semiconductor device, and the environment in which it is used, and one of the required items is a room temperature storage characteristic. Conventionally used curing accelerators in the resin composition include 2-methylimidazole, 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, and the like. Since the agent exhibits a curing promoting action even at a relatively low temperature, resin compositions using these have insufficient storage characteristics at room temperature, and when stored at room temperature, poor filling due to a decrease in fluidity during molding or Problems such as disconnection of the gold wire of the IC chip and occurrence of conduction failure occur. For this reason, the resin composition needs to be refrigerated and transported under refrigeration, and at present it is costly to store and transport. Further, in recent years, the use conditions of electric / electronic parts have become more and more severe, and the level of characteristics required for the resin composition, particularly, the humidity resistance reliability has been increasing.

[0003]

The present invention relates to an epoxy resin composition for semiconductor encapsulation which is suitable for insertion mounting and surface mounting, which is excellent in room temperature storage characteristics, moisture resistance reliability and moldability, and a semiconductor device using the same. Things.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have found that a specific tetra-substituted phosphonium and a compound having two or more phenolic hydroxyl groups in one molecule are obtained. The present inventors have found that an epoxy resin composition using a salt with a conjugate base as a curing accelerator exhibits the above-described excellent properties, and have completed the present invention based on this finding. That is, the present invention provides (A) an epoxy resin,
(B) a phenolic resin, (C) a salt of a tetra-substituted phosphonium as a curing accelerator and a conjugate base of a compound having two or more phenolic hydroxyl groups in one molecule, and two or more phenolic compounds in one molecule The conductivity of the extraction water of the compound having a hydroxyl group is 1000 μS / cm or less, and (D) an inorganic filler is an essential component, and the equivalent ratio of the epoxy group of all epoxy resins to the phenolic hydroxyl group of all phenol resins is 0.5 to 2. An epoxy resin composition characterized in that the compounding amount of the inorganic filler (D) is 200 to 2400 parts by weight per 100 parts by weight of the total amount of all epoxy resins and all phenol resins, and The present invention relates to a semiconductor device characterized by being sealed by sealing.

[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. For example, biphenyl epoxy resin, bisphenol epoxy resin, stilbene epoxy resin, orthocresol novolak epoxy resin, phenol novolak epoxy resin, triphenolmethane epoxy resin, alkyl-modified triphenolmethane epoxy resin, epoxy containing triazine nucleus Resin, dicyclopentadiene-modified phenolic epoxy resin, etc., may be used, and these may be used alone or in combination. Among these epoxy resins, a crystalline epoxy resin having a melting point of 50 to 150 ° C. is preferable. Such a crystalline epoxy resin has a rigid structure such as a biphenyl skeleton, a bisphenol skeleton, or a stilbene skeleton in a main chain, and is relatively low in molecular weight, and thus exhibits crystallinity. The crystalline epoxy resin is a solid that crystallizes at room temperature, but rapidly melts and changes to a low-viscosity liquid in a temperature range higher than the melting point. The melting point of the crystalline epoxy resin indicates the temperature at the top of the endothermic peak of crystal melting, which was heated at a rate of 5 ° C./min from room temperature using a differential scanning calorimeter.

As the crystalline epoxy resin satisfying these conditions, in particular, one or more selected from the general formulas (1) and (2) or the stilbene type epoxy resin represented by the general formula (3) and the general formula (3) A mixture with the stilbene type epoxy resin represented by (4) is preferable.

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[0007]

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[0008]

Embedded image (Wherein, R ^{3 to} R ¹⁰ each independently represent a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. However, carbon-carbon The two aryl groups attached to the double bond are different from each other.)

[0009]

Embedded image (Wherein, R ^{11 to} R ¹⁴ each independently represent a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. However, carbon-carbon The two aryl groups bonded to the double bond are the same as each other.)

[0010] Formula substituent R ² of the bisphenol type epoxy resin represented by the substituent R ¹ of the biphenyl type epoxy resin represented by (1), and general formula (2) is a hydrogen atom and a A chain or cyclic alkyl group, a phenyl group, or a group or atom selected from halogen, which may be the same or different from each other, for example, a methyl group, an ethyl group, a propyl group, a butyl group, Examples thereof include a cyclohexyl group, a phenyl group, a chlorine atom and a bromine atom, and a methyl group is particularly preferable. The substituents R ^{3 to} R ¹⁴ of the stilbene type epoxy resin represented by the general formula (3) and the general formula (4) are selected from a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or halogen. Selected groups or atoms, which may be the same or different, for example, a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, an amyl group, a hexyl group (including each isomer) , A cyclohexyl group, a chlorine atom, a bromine atom, etc., and particularly, a methyl group, an ethyl group, a propyl group, or a butyl group is preferable in view of a low melt viscosity of the epoxy resin.

This epoxy resin is a mixture of a stilbene-type epoxy resin of the general formula (3) and a stilbene-type epoxy resin of the general formula (4). The stilbene-type epoxy resin of the general formula (3) and the general formula (3) The stilbene type epoxy resins of 4) include those having various structures depending on the type of the substituent and the like. Each of the stilbene type epoxy resins of the general formulas (3) and (4) has one type of structure. Or a mixture of two or more types of structures.
Mixing of the stilbene-type epoxy resin of the general formula (3) and the stilbene-type epoxy resin of the general formula (4) only needs to lower the melting point by mixing both compounds, and the mixing method is not particularly limited. For example, there is a method of mixing stilbene-type phenols, which are raw materials of the stilbene-type epoxy resin, before glycidyl etherification, or a method of melting and mixing both stilbene-type epoxy resins. 50-150 ° C
Adjust so that

As the stilbene type epoxy resin represented by the general formula (3), from the viewpoint of availability, performance and raw material price, 5
-Tert-butyl-4,4'-dihydroxy-2,
Glycidyl etherified products of 3 ', 5'-trimethylstilbene and 3-tert-butyl-4,4'-dihydroxy-3', 5,5'-trimethylstilbene are particularly preferred. As the stilbene-type epoxy resin represented by the general formula (4), 4,4′-dihydroxy-3,3 ′, 5,5′-tetramethylstilbene,
4'-dihydroxy-3,3'-ditert-butyl-
Glycidyl etherified products of 6,6′-dimethylstilbene and 4,4′-dihydroxy-3,3′-ditert-butyl-5,5′-dimethylstilbene are particularly preferred.

The phenolic resin used in the present invention comprises 1
It refers to all monomers, oligomers and polymers having two or more phenolic hydroxyl groups in the molecule. For example, phenol novolak resin, cresol novolak resin,
Para-xylylene-modified phenolic resin, para-xylylene
Meta-xylylene-modified phenolic resin, terpene-modified phenolic resin, dicyclopentadiene-modified phenolic resin and the like can be mentioned, and these may be used alone or in combination. These phenol resins can be used without any limitation in molecular weight, softening point, hydroxyl equivalent, and the like. The equivalent ratio of the epoxy group of all epoxy resins used in the present invention to the phenolic hydroxyl group of all phenol resins is preferably 0.5
To 2, particularly preferably 0.7 to 1.5. 0.5 ~
Outside the range 2, the curability, moisture resistance and the like are undesirably reduced.

The curing accelerator used in the present invention is a conjugate base of a compound having two or more phenolic hydroxyl groups in one molecule with a tetra-substituted phosphonium (hereinafter referred to as 1).
The conjugate base of a compound having two or more phenolic hydroxyl groups in the molecule is called an anion). The electric conductivity of the extraction water of the compound having two or more phenolic hydroxyl groups in one molecule to be used needs to be 1000 μS / cm or less. The method for measuring the conductivity of the extraction water according to the present invention is a method for measuring the conductivity of a compound 1 having two or more phenolic hydroxyl groups in one molecule.
g in pure water (the conductivity of pure water used is 5 μS / cm or less)
50 g and 125 in a pressure cooker
After treating at 20 ° C. for 20 hours, the contents of the pressure cooker container are taken out, and the electric conductivity of the water layer obtained by centrifugation is measured by a conductivity meter (Horiba, Ltd., ES-).
14) at room temperature. That is, the curing accelerator of the present invention comprises a salt of a tetra-substituted phosphonium and a conjugate base of a compound having two or more phenolic hydroxyl groups in one molecule, having a conductivity of 1000 μS / cm or less in extraction water. It is.

Examples of such salts include tetraphenylphosphonium resorcinol, tetraphenylphosphonium bisphenol A, tetraphenylphosphonium bisphenol F, tetraphenylphosphonium bisphenol S, tetraphenylphosphonium biphenol, and tetraphenylphosphonium dihydroxynaphthalene. Salt, tetraphenylphosphonium phenol novolak resin salt, tetraphenylphosphonium aralkyl-modified phenol resin salt, tetrabutylphosphonium bisphenol A salt, tetrabutylphosphonium bisphenol F salt, tetrabutylphosphonium bisphenol S salt, tetrabutylphosphonium biphenol salt, tetrabutylphosphonium dihydroxy Naphthalene salt, tetrabutyl phospho Umm phenol novolac resin salt,
Tetrabutylphosphonium aralkyl-modified phenolic resin salt, triphenylethylphosphonium bisphenol A salt, tolylmethylphosphonium bisphenol F
Salt, trianisylethylphosphonium biphenol salt,
Examples thereof include triphenylbutylphosphonium dihydroxynaphthalene salt, triphenylethylphosphonium phenol novolak resin salt, and triphenylbutylphosphonium aralkyl-modified phenol resin salt.

In the component (C), the compound having two or more phenolic hydroxyl groups in one molecule, which is a conjugate acid of an anion, has an electrical conductivity of 1000 μS / cm or less for extracted water, which is excellent in moisture resistance and reliability. It is an essential condition to obtain the property. The reason for this is that in the pressure cooker bias test (PCBT), the electrophoresis phenomenon caused by ionic impurities around the element to which a voltage is applied is considered to be the cause of the corrosion of the aluminum wiring. It is considered that there is a correlation between the rate and the humidity resistance reliability. Further, when the compound having a phenolic hydroxyl group has less than two phenolic hydroxyl groups in one molecule, the reactivity of the corresponding conjugate base is low, so that the compound is not taken into the crosslinked structure during curing and is released. The conjugate base may affect moisture resistance reliability and curability. On the other hand, the substituent of the phosphorus atom on the cation side is preferably water-repellent, and a phenyl group is particularly preferable. From the above, the tetra-substituted phosphonium of the component (C) is tetraphenylphosphonium, and the conjugate base of the compound having two or more phenolic hydroxyl groups in one molecule is resorcin, bisphenol A, bisphenol F, bisphenol S, Biphenol, dihydroxynaphthalene,
Most preferred is at least one selected from the group consisting of conjugate bases of phenol novolak resins and aralkyl-modified phenol resins. In addition, triphenylphosphine, 1,8, or the like may be used as long as the properties of these curing accelerators are not impaired.
-Diazabicyclo (5,4,0) undecene-7,2-
There is no problem when used in combination with other curing accelerators such as methylimidazole.

The type of the inorganic filler used in the present invention is not particularly limited, and those generally used for a sealing material can be used. For example, fused crushed silica powder, fused spherical silica powder, crystalline silica powder, secondary aggregated silica powder, alumina, titanium white, aluminum hydroxide, talc, clay, glass fibers, and the like,
Particularly, a fused spherical silica powder is preferable. The shape is preferably infinitely spherical, and the filling amount can be increased by mixing particles having different particle sizes. The mixing amount of the inorganic filler is 200 per 100 parts by weight of the total amount of all epoxy resins and all phenol resins.
~ 2400 parts by weight are preferred. If less than 200 parts by weight,
The reinforcing effect of the inorganic filler may not be sufficiently exerted, and if it exceeds 2400 parts by weight, the fluidity of the resin composition may be reduced, resulting in poor filling during molding, which is not preferable. In particular, when the blending amount of the inorganic filler is 250 to 1,400 parts by weight per 100 parts by weight of the total amount of all epoxy resins and all phenol resins, the moisture absorption of the cured product of the resin composition becomes low, and solder cracks are generated. Can be prevented, and the viscosity of the resin composition at the time of melting is reduced, so that there is no possibility of causing gold wire deformation inside the semiconductor device, which is more preferable. It is preferable that the inorganic filler is sufficiently mixed in advance.

The resin composition of the present invention may contain, in addition to the components (A) to (D), a coupling agent such as γ-glycidoxypropyltrimethoxysilane, a coloring agent such as carbon black, bromination, if necessary. Epoxy resin, antimony oxide, flame retardants such as phosphorus compounds, silicone oil, low stress components such as silicone rubber, natural wax, synthetic wax, higher fatty acids and release agents such as metal salts or paraffin,
Various additives such as antioxidants can be blended. The resin composition of the present invention is obtained by mixing the components (A) to (D) and other additives at room temperature using a mixer, kneading the mixture with a kneader such as a roll or an extruder, cooling, and pulverizing. Can be In order to manufacture a semiconductor device by encapsulating an electronic component such as a semiconductor using the resin composition of the present invention, it is sufficient to cure and mold by a molding method such as a transfer mold, a compression mold, and an injection mold.

[0019]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. The mixing ratio is by weight. First, the structures of Compounds 1 to 6, which are curing accelerators used in Examples and Comparative Examples, are collectively shown below. Table 1 shows the names of the conjugate acids corresponding to the conjugate bases of the compounds having a phenolic hydroxyl group of compounds 1 to 6 and 1 g of each conjugate acid mixed with 50 g of pure water. The conductivity of the extracted water obtained by the time treatment is summarized below.

Compound 1

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Compound 2

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Compound 3

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Compound 4

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Compound 5

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Compound 6

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[0026]

[Table 1]

Example 1 51 parts by weight of a resin mainly composed of a biphenyl type epoxy resin of the formula (5) (epoxy equivalent: 185, melting point: 105 ° C.)

Embedded image 49 parts by weight of the phenolic resin of the formula (6) (softening point 73 ° C.)

[0028]

Embedded image Compound 1 3.8 parts by weight Fused spherical silica (average particle size 15 μm) 500 parts by weight Carbon black 2 parts by weight Brominated bisphenol A type epoxy resin 2 parts by weight Carnauba wax 2 parts by weight was mixed and heated with a hot roll to give 95 parts. The mixture was kneaded at 8 ° C. for 8 minutes, cooled and pulverized to obtain a resin composition. The obtained resin composition was evaluated by the following method. Table 2 shows the results.

Evaluation method Spiral flow: Spiral flow was measured using a mold for spiral flow measurement in accordance with EMMI-I-66 at a mold temperature of 175 ° C., an injection pressure of 70 kg / cm ² , and a curing time of 2 minutes. Spiral flow is a parameter of fluidity, and the larger the value, the better the fluidity. The unit is cm. Shore D hardness: mold temperature 175 ° C, injection pressure 70kg /
The resin was molded in 2 cm ² and a curing time of 2 minutes, and the value of the Shore D hardness measured 10 seconds after opening the mold was taken as the curability. Shore D hardness is an index of curability, and the larger the numerical value, the better the curability. Solder crack resistance: mold temperature 175 ° C, injection pressure 70k
g / cm ² , curing time 2 minutes, 80 pQFP (thickness 2.
0mm) 8 pieces are molded at 85 ° C and 85% relative humidity.
After the treatment for 8 hours, the substrate was treated for 10 seconds by IR reflow at 240 ° C., and the number of package cracks was visually observed. When the number of cracked packages is n, it is indicated as n / 8. Storage at 30 ° C .: After storing at 30 ° C. for 6 months, the spiral flow is measured and expressed as a percentage of the spiral flow immediately after preparation. Units%. Moisture resistance reliability: mold temperature 175 ° C, pressure 70kg / c
After molding 16pDIP with m ² and curing time of 2 minutes,
Post-curing was performed at 5 ° C. for 8 hours. 125 ° C, relative humidity 1
After applying a voltage of 20 V in 00% water vapor, disconnection failure was examined. The time until a defect appeared in eight or more of the 15 packages was defined as a defect time. The unit is time. The measurement time was 500 hours at the maximum. If the number of defective packages was less than 8 at that time, the defective time was 5 hours.
It was indicated as over 00 hours. The longer the failure time, the better the moisture resistance reliability.

Examples 2 to 8, Comparative Examples 1 to 3 Resin compositions were obtained in the same manner as in Example 1 according to the formulations in Tables 2 and 3, and evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3. The crystalline epoxy resin A used in Example 2 was a resin 60 containing 4,4′-bis (2,3-epoxypropoxy) -3,3 ′, 5,5′-tetramethylstilbene as a main component. Weight% and 4,4′-bis (2,
3-epoxypropoxy) -5-tert-butyl-
It is a mixture of 2,3 ′, 5′-trimethylstilbene and a resin containing 40% by weight as a main component (an epoxy equivalent of 20%).
9, melting point 120 ° C). The ortho-cresol novolak type epoxy resin used in Example 3 had an epoxy equivalent of 20.
0, softening point 65 ° C. The phenol novolak resin used in Example 3 had a hydroxyl equivalent of 104 and a softening point of 105.
° C. In Comparative Example 1, when the compound 6 having a conductivity of the extraction water of the corresponding conjugate acid exceeding 1000 μS / cm was used as the curing accelerator, the moisture resistance reliability was reduced. Comparative Example 2
When triphenylphosphine was used as the curing accelerator, the failure time in the moisture resistance reliability was good, but the storage stability was lowered. In Comparative Example 3, Compound 1 was used as a curing accelerator.
When 180 parts by weight of fused spherical silica was used as the inorganic filler, the amount of the inorganic filler was small, and the solder crack resistance was reduced.

[Table 2]

[0031]

[Table 3]

[0032]

The epoxy resin composition of the present invention is excellent in room temperature storage characteristics and moldability for encapsulating semiconductors, and a semiconductor device using the same has a moisture resistance reliability as a device compatible with insertion mounting and surface mounting. Excellent and useful.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (Reference) H01L 23/31 F-term (Reference) 4J002 CC042 CC052 CD011 CD051 CD061 CD071 CD141 DE137 DE147 DJ017 DJ037 DJ047 DL007 EW176 FD017 FD142 FD156 GQ00 4J036 AC02 AD03 AD04 AD05 AD07 AD08 AD09 AD10 AF06 AF08 AJ14 AJ18 DB05 FA03 FA05 FB07 FB08 GA04 JA07 4M109 AA01 BA01 CA21 EA02 EA06 EB03 EB04 EC01 EC03 EC14

Claims (7)

[Claims] 1. A salt of (A) an epoxy resin, (B) a phenolic resin, (C) a salt of a tetra-substituted phosphonium as a curing accelerator and a conjugate base of a compound having two or more phenolic hydroxyl groups in one molecule, And a compound having two or more phenolic hydroxyl groups in one molecule has an electric conductivity of 1 in extracted water.
000 μS / cm or less, and (D) an inorganic filler as an essential component, and an equivalent ratio of epoxy groups of all epoxy resins to phenolic hydroxyl groups of all phenolic resins is 0.5 to 2,
The compounding amount of the inorganic filler (D) is 200 to 240 per 100 parts by weight of the total amount of all epoxy resins and all phenol resins.
An epoxy resin composition, which is 0 parts by weight. 2. The conjugate base of a compound having two or more phenolic hydroxyl groups in one molecule is a conjugate of resorcin, bisphenol A, bisphenol F, bisphenol S, biphenol, dihydroxynaphthalene, phenol novolak resin, and aralkyl-modified phenol resin. The epoxy resin composition according to claim 1, which is at least one member selected from the group consisting of bases. 3. The epoxy resin composition according to claim 1, wherein the tetra-substituted phosphonium is tetraphenylphosphonium. 4. The epoxy resin composition according to claim 1, wherein the epoxy resin is a crystalline epoxy resin having a melting point of 50 to 150 ° C. 5. The epoxy resin composition according to claim 4, wherein the crystalline epoxy resin having a melting point of 50 to 150 ° C. is at least one selected from the general formulas (1) and (2). Embedded image (In the formula, R ¹ is a group or an atom selected from a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, or a halogen, and may be the same or different. Good.) (In the formula, R ² is a group or atom selected from a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, a phenyl group, or a halogen, and may be the same or different. Good.) 6. The crystalline epoxy resin having a melting point of 50 to 150 ° C. is a mixture of a stilbene type epoxy resin represented by the general formula (3) and a stilbene type epoxy resin represented by the general formula (4). The epoxy resin composition according to the above. Embedded image (Wherein, R ^{3 to} R ¹⁰ each independently represent a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. However, carbon-carbon (The two aryl groups bonded to the double bond are different from each other.) (Wherein, R ^{11 to} R ¹⁴ each independently represent a hydrogen atom, a chain or cyclic alkyl group having 1 to 6 carbon atoms, or a group or atom selected from halogen. However, carbon-carbon The two aryl groups bonded to the double bond are the same as each other.) 7. A semiconductor device sealed with the epoxy resin composition according to claim 1, 2, 3, 4, 5, or 6.