JPH1180321A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having excellent quick curability, moldability, storage stability, etc., by compounding a specific amount of a mixture of two kinds of stilbene-type epoxy resins with a phenolic resin, a plurality of cure accelerators and an inorganic filler. SOLUTION: The objective composition is produced by compounding (A) a mixture of stilbene-type epoxy resins of the formula I (R1 to R8 are each a 1-6C alkyl, etc.) and the formula II (R9 to R12 are each a 1-6C alkyl, etc.) (preferably having a melting point of 150-200 deg.C) with (B) a phenolic resin having >=2 phenolic hydroxyl groups in one molecule, (C) tetraphenyl, phosphonium.tetranaphthoyloxyborate, (D) a compound selected from triphenylphosphine, 1,8-diazabicyclo(5,4,0)undecene-7 and 2-methylimidazole and (E) an inorganic filler. The equivalent ratio of the epoxy group in the total epoxy resin to the phenolic hydroxyl group in the total phenolic resin is 0.5-2 and the amount of the component E is 200-2,400 pts. wt. based on 100 pts.wt. of A+B.

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 fast-curing properties, moldability, storage stability and package crack resistance, and a semiconductor device using the same.

[0002]

2. Description of the Related Art Epoxy resin compositions (hereinafter referred to as resin compositions) have been developed and produced for protecting semiconductors from mechanical and chemical actions. Generally, a resin composition contains a curing accelerator in order to accelerate the curing reaction between an epoxy resin and a curing agent.However, many curing accelerators exhibit a curing acceleration effect even at a relatively low temperature range such as room temperature. Curing also proceeds by the heat applied when mixing the component with other compounding components. Further, when the resin composition is stored, the curing proceeds gradually at room temperature. If the curing of the resin composition proceeds too much, it causes a decrease in fluidity and deformation of a gold wire at the time of molding, and the quality of the resin composition deteriorates. In addition, there is a problem that cracks are generated when mounting a semiconductor package as an item required for the resin composition. This is because the cured product of the resin composition is exposed to a high temperature such as being directly immersed in a solder bath at the time of mounting, and the moisture absorbed by the cured product of the resin composition expands, resulting in a crack. For this reason, the cured product of the resin composition is required to have low hygroscopicity, and as a result of various studies on this requirement, the inclusion of a large amount of the inorganic filler in the resin composition has significantly improved package crack resistance. Improved. As a method of high filling of this inorganic filler,
There are changes in the particle size distribution and shape of the inorganic filler, reduction in the viscosity of the epoxy resin and phenol resin, and the like, but these methods are mostly used in combination. As a low-viscosity epoxy resin, a glycidyl ether type epoxy resin having a biphenyl skeleton has been developed and actually used. Although the resin composition using this biphenyl type epoxy resin has low moisture absorption and is excellent as a sealing material for surface mounting, it is not sufficient from the viewpoint of heat resistance, and package cracks occur under high temperature moisture absorption conditions. There is a problem. In order to improve this problem, an epoxy resin having a stilbene skeleton in which two aryl groups bonded to a carbon-carbon double bond are the same as each other as a stiffer skeleton than a biphenyl skeleton has been developed. . However, many of the epoxy resins having a stilbene skeleton as described above,
When used alone, it has a high melting point, is difficult to knead with each component of the resin composition, and has poor workability. As a method of improving the poor workability, Japanese Patent Laid-Open Publication No. Hei 8-301981 discloses a stilbene type epoxy having different aryl groups bonded to a carbon-carbon double bond of a stilbene skeleton and having a melting point of 150 ° C. or less. A mixture of one or more resins, or one or more stilbene-type epoxy resins having the same aryl group bonded to the carbon-carbon double bond of the stilbene skeleton with the stilbene skeleton, and phenol A resin composition containing a resin-based curing agent has been proposed, and the workability has been improved. That is, this publication proposes a resin composition that is superior in heat resistance to a biphenyl-type epoxy resin and does not generate a package crack under high-temperature moisture absorption conditions. However, the stilbene-type epoxy resin or the stilbene-type epoxy resin mixture disclosed in this publication, like the biphenyl-type epoxy resin, has a low molecular weight of the epoxy resin to reduce the viscosity. Is easy to move, and the curing reaction proceeds easily in the initial stage of the reaction. Furthermore, since the polymer has a low molecular weight, the crosslink density is not sufficiently increased at the final stage of the reaction, and the curability of the resin composition is lowered.

[0003] In recent years, studies have been made to develop a so-called latent catalyst which does not exhibit a curing accelerating action at a relatively low temperature range such as normal temperature but exhibits a curing accelerating action only at a high temperature range during molding. . By blending the latent catalyst into the resin composition, the curing reaction in a relatively low temperature range such as room temperature hardly progresses.
It has become possible to increase the amount of the latent catalyst to harden a low molecular weight epoxy resin or phenol resin to a high degree, and resin compositions having storage stability and solder crack resistance have been developed. However, even with the above resin composition, a problem may occur depending on the conditions used. For example, moldability in a short molding time tends to be inferior. For a quick-curing resin composition for short-time curing, a usual molding temperature (170 to 185) is used.
C), and good moldability under conditions of a molding time of about 30 to 35 seconds is required. However, in the case of a resin composition cured with only a latent catalyst, in addition to the time required to activate the latent catalyst in the resin composition during molding, it is necessary to have sufficient time to promote the reaction after activation. Depending on the structure of the package to be sealed, short molding time may not provide sufficiently good moldability.

[0004] Further, there is the problem of usbari. Usbari is caused by the low molecular weight component in the resin component.However, in a resin composition cured with only a latent catalyst, it occurs because the reaction of the resin component, especially even the low molecular weight component, in the resin component during kneading is suppressed. It will be easier. Also, this phenomenon tends to occur when the degree of wear of the molding die increases.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a quick-curing,
An object of the present invention is to provide a resin composition for semiconductor encapsulation which is excellent in moldability, particularly excellent usability, storage stability and package crack resistance, and a semiconductor device using the same.

[0006]

The present invention provides (A) a mixture of a stilbene type epoxy resin represented by the general formula (1) and a stilbene type epoxy resin represented by the general formula (2), and (B) one molecule. A phenolic resin having two or more phenolic hydroxyl groups therein, (C) tetraphenylphosphonium tetranaphthoyloxyborate, (D) triphenylphosphine, 1,8-diazabicyclo (5,4,
0) At least one of undecene-7 or 2-methylimidazole and (E) an inorganic filler are essential components, and the equivalent ratio of the epoxy group of all epoxy resins to the phenolic hydroxyl group of all phenol resins is 0.1. 5 to 2, wherein the blending amount of the inorganic filler (E) is 200 to 2400 parts by weight per 100 parts by weight of the total amount of all epoxy resins and all phenolic resins.

Embedded image (Wherein, R _{1 to} R ₈ each independently represent 1 to 6 carbon atoms)
Represents a chain or cyclic alkyl group, a hydrogen atom or a halogen atom. The two aryl groups attached to the carbon-carbon double bond are different from each other. )

[0007]

Embedded image (Where R _{9 to} R ₁₂ each independently represent a carbon number of 1 to
6 represents a chain or cyclic alkyl group, a hydrogen atom, or a halogen atom. The two aryl groups attached to the carbon-carbon double bond are the same as each other. )

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The general formula (1) used in the present invention
And the substituents R _{1 to} R ₁₂ of the stilbene type epoxy resin represented by (2) include, for example, methyl group, ethyl group, propyl group, butyl group, amyl group, hexyl group (including each isomer), Examples include a cyclohexyl group, a chlorine atom, and a bromine atom. Among these, from the low melt viscosity of the resin, methyl group, ethyl group, propyl group,
And butyl groups are more preferred. The epoxy resin used in the present invention is a mixture of a stilbene type epoxy resin of the general formula (1) and a stilbene type epoxy resin of the general formula (2). The stilbene type epoxy resin of the general formula (1) and the stilbene type epoxy resin of the general formula (2) both have various structures depending on the type of the substituent and the like.
Each of the stilbene-type epoxy resins of the general formula (2) may have a single structure or a mixture of two or more structures. The mixing method of the stilbene-type epoxy resin of the general formula (1) and the stilbene-type epoxy resin of the general formula (2) is not particularly limited as long as the melting point is reduced by mixing both resins. 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 melt-mixing both stilbene-type epoxy resins. The melting point of the mixture of the stilbene type epoxy resin of the general formula (1) and the stilbene type epoxy resin of the general formula (2) is preferably from 150 to 50 ° C. 150
If the temperature exceeds ℃, there is a possibility that a problem may occur in workability such as kneading with other components constituting the resin composition, which is not preferable. If the temperature is lower than 50 ° C., the epoxy resin is liable to solidify, which may cause a problem in workability such as measurement during preparation, which is not preferable. The melting point of the stilbene-type epoxy resin of the present invention indicates the temperature at the top of the endothermic peak of crystal melting when the temperature is raised from room temperature at a rate of 5 ° C./min using a differential scanning calorimeter. The stilbene-type epoxy resin of the general formula (1) used in the present invention is obtained by glycidyl etherification of stilbene-type phenols in which two aryl groups bonded to a carbon-carbon double bond are different from each other. However, from the viewpoint of availability, performance, and raw material price, 5-tert-butyl-4,4'-dihydroxy-2,3 ', 5'-trimethylstilbene and 3-tert-butyl-4,4 '-Dihydroxy
-3 ', 5,5'-Trimethylstilbene is particularly preferred. The stilbene type epoxy resin of the general formula (2) is obtained by glycidyl etherification of a stilbene type phenol in which two aryl groups bonded to a carbon-carbon double bond as a raw material are the same as each other. In terms of raw material prices, 4,4'-dihydroxy-3,3 ', 5,5'-tetramethylstilbene, 4,4'-dihydroxy-3,3'-ditert-butyl-6,
6'-dimethylstilbene, 4,4'-dihydroxy-3,3'-ditert-butyl-5,5'-dimethylstilbene are particularly preferred. More preferably, a mixture of the stilbene type epoxy resin represented by the general formula (1) and the stilbene type epoxy resin represented by the general formula (2) is 4,4′-bis (2,3-epoxypropoxy) -5 -Tert-butyl-2,3 ', 5'-trimethylstilbene 20 to 60% by weight and 4,4'-bis (2,3-epoxypropoxy) -3,3', 5,5'-tetramethylstilbene 40
~ 80% by weight, and those within this range have particularly good performance,
Has excellent properties such as raw material prices. Further, the stilbene type epoxy resin may be used in combination with another epoxy resin. Examples of the epoxy resin to be used in combination include bisphenol A type epoxy resin, bromine-containing epoxy resin, bisphenol F type epoxy resin, bisphenol AD type epoxy resin, biphenyl type epoxy resin, dihydroxydiphenylmethane type epoxy resin, phenol novolak type epoxy resin, and cresol. Novolak epoxy resin, cycloaliphatic epoxy resin, glycidyl ester epoxy resin, glycidylamine epoxy resin, heterocyclic epoxy resin, trifunctional epoxy resin, trishydroxyphenylmethane epoxy resin, and dicyclopentadiene and phenols And the like. Epoxy resins obtained by glycidyl etherification of a phenol resin obtained by polymerizing a phenol resin by an addition reaction are mentioned, and these may be used alone or in combination. The epoxy resin of the present invention refers to monomers, oligomers, and polymers in general.

The phenolic resin having two or more phenolic hydroxyl groups in one molecule used in the present invention refers to monomers, oligomers and polymers in general, such as phenol novolak resin, cresol novolak resin,
Para-xylylene-modified phenolic resin, meta-xylylene
Examples thereof include a paraxylylene-modified phenol resin, a terpene-modified phenol resin, and a dicyclopentadiene-modified phenol resin. These may be used alone or in combination. These phenol resins can be used without any particular limitation in molecular weight, softening point, hydroxyl equivalent, and the like.

The equivalent ratio of the epoxy groups of all epoxy resins used in the present invention to the phenolic hydroxyl groups of all phenolic resins is preferably 0.5-2, especially 0.7-1.
5 is more preferred. If the ratio is out of the range of 0.5 to 2, the moisture resistance, the curability and the like are undesirably reduced.

The tetraphenylphosphonium tetranaphthoyloxyborate used in the present invention is a latent curing accelerator. Since this curing accelerator does not show catalytic activity in a relatively low temperature range, the curing reaction of the resin composition does not proceed. That is, at the time of kneading the respective components, a part of the cross-linking reaction does not proceed rapidly, so that a predetermined fluidity is maintained, and for the same reason, the resin composition is excellent in the room temperature storage stability. In addition, in the high temperature range during molding, the catalyst exhibits higher catalytic activity than conventional curing accelerators, and cures the resin composition to a high degree.

Triphenylphosphine (hereinafter referred to as TPP), 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU), 2-methylimidazole (hereinafter referred to as 2MZ) used in the present invention.
Are general epoxy resin curing accelerators,
It has a hardening promoting effect even in a relatively low temperature range such as normal temperature. By using at least one of these curing accelerators and a latent curing accelerator, tetraphenylphosphonium / tetranaphthoyloxyborate, in addition to storage stability and solder crack resistance, rapid curing and molding This makes it possible to obtain a resin composition having both properties and, in particular, Usbari characteristics. In other words, by using tetraphenylphosphonium / tetranaphthoyloxyborate, the curing reaction does not proceed even when the resin component and other components are kneaded, and also suppresses the deterioration of the quality of the resin composition during storage. In addition, the storage stability is improved, and the inorganic filler can be highly filled while having sufficient fluidity, so that the solder crack resistance is also improved. Furthermore, for fast curing and preventing burrs, TPP, DBU or 2MZ
One or more of them is selected depending on the molding time and the type of the semiconductor package, but there is no problem if two or more kinds are used in combination. Since these curing accelerators have a curing promoting action even in a relatively low temperature range such as room temperature, it promotes curing of a low-molecular weight component that is easily movable when kneading with a resin component and other components, thereby preventing burrs. In addition, since the catalyst has a high catalytic activity in a high temperature range during molding, it is useful for quick curing. The compounding amount of tetraphenylphosphonium / tetranaphthoyloxyborate is desirably 50 to 95% by weight in the total curing accelerator.

The total amount of the curing accelerator used in the present invention is preferably 0.4 to 20 parts by weight per 100 parts by weight of the total of all epoxy resins and all phenolic resins, and is usually mixed at 70 to 150 ° C. be able to. If the amount is less than 0.4 parts by weight, sufficient curability may not be obtained during heat molding, while if it exceeds 20 parts by weight,
It is not preferable because the curing is too fast and there is a possibility that poor filling may occur due to a decrease in fluidity during molding.

The type of the inorganic filler used in the present invention is not particularly limited, and an inorganic filler generally used for a sealing material can be used. For example, fused silica powder, fused spherical silica powder, crystalline silica powder,
Secondary aggregated silica powder, alumina, titanium white, aluminum hydroxide, talc, clay, glass fiber, and the like are listed, and fused spherical silica powder is particularly preferred. The shape is preferably infinitely spherical, and the filling amount can be increased by mixing particles having different particle sizes. The compounding amount of the inorganic filler is preferably 200 to 2400 parts by weight per 100 parts by weight of the total amount of all epoxy resins and all phenol resins. If it is less than 200 parts by weight, the reinforcing effect of the inorganic filler may not be sufficiently exhibited, and if it is more than 2400 parts by weight, the fluidity of the resin composition may be reduced, and poor filling or the like may occur during molding. Absent. In particular, when the compounding 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 phenolic resins, the moisture absorption of the cured product of the resin composition is low for semiconductor encapsulation, The generation of cracks can be prevented, and the viscosity of the resin composition at the time of melting is lowered, so that there is no possibility of causing gold wire deformation inside the semiconductor package, which is more preferable. It is preferable that the inorganic filler used in the present invention is sufficiently mixed in advance. Also, if necessary, the inorganic filler may be pre-treated with a coupling agent or a resin and used, and as a treatment method, a method of removing the solvent after mixing using a solvent, or directly treating the inorganic filler. There is a method of adding and treating using a mixer.

The resin composition of the present invention comprises, in addition to the components (A) to (E), if necessary, a coloring agent such as carbon black, a brominated epoxy resin, a flame retardant such as antimony oxide and a phosphorus compound, and γ- Coupling agents such as glycidoxypropyltrimethoxysilane, 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 (E) and other additives at room temperature using a mixer, kneading the mixture with a kneading machine 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 only necessary to cure and mold by a conventional molding method such as transfer molding, compression molding and injection molding.

[0016]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited to these examples. The mixing unit is parts by weight. The chemical formula of tetraphenylphosphonium / tetranaphthoyloxyborate is shown below.

Embedded image

Example 1 Epoxy Resin A (4,4′-bis (2,3-epoxypropoxy) -5-tert-butyl-2,3 ′, 5′-trimethylstilbene 40% by weight of resin Of a resin having a main component of 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetramethylstilbene at a melting point of 120 ° C and an epoxy equivalent of 209 55.6 parts by weight Phenol resin of the formula (3) (softening point 73 ° C.) 44.4 parts by weight

Embedded image Tetraphenylphosphonium / tetranaphthoyloxyborate (hereinafter referred to as TPP K-NA) 5.0 parts by weight TPP 1.5 parts by weight Fused spherical silica (average particle size 15 μm) 830 parts by weight Carbon black 2.0 parts by weight Bromination 1.7 parts by weight of a phenol novolak type epoxy resin, 2.8 parts by weight of carnauba wax were mixed at room temperature using a mixer, kneaded at 100 ° C. using a biaxial roll, cooled and pulverized to obtain a resin composition. Was. The obtained 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-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. Unit cm. Storage at 30 ° C .: After storing the resin composition at 30 ° C. for 1 week, the spiral flow was measured and expressed as a percentage of the spiral flow immediately before entering the storage test. The larger the value, the better the preservability. unit%. Package crack resistance: 80 pQFP (thickness: 1.5 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 2 minutes, and was post-cured at 175 ° C. for 8 hours. Then, eight packages were obtained. After absorbing moisture for 168 hours at 85 ° C. and a relative humidity of 85%, IR reflow at 240 ° C. was performed twice for 10 seconds, and package cracks were visually observed. When n packages had cracks, n / 8 Is displayed. Rapid curability: Using a low-pressure transfer molding machine, 16 pDIP (3.5 mm thick) was molded at a molding temperature of 175 ° C., a pressure of 70 kg / cm ² , and a curing time of 30 seconds, and the rapid curability was evaluated. A sample having good mold release from the mold and a molded product were evaluated as ○, and a sample having poor release was evaluated as ×. Usbari characteristics: using a low-pressure transfer molding machine, molding temperature 175 ° C., pressure 150 kg / cm ² , curing time 2
A molded article was formed in minutes. The mold is one pot and 14
Each cavity has an air vent (4mm wide x 20µm thick) at the end of each cavity.
Usbari flowing out of the air vent was evaluated. In the evaluation, the sum of the lengths of the Usbari portions of all 14 cavities was used as the score of the Usbari characteristics, and the smaller the score, the better the Usbari characteristics.

Examples 2 to 5 Compounded according to the formulation shown in Table 1, a resin composition was obtained in the same manner as in Example 1, and evaluated in the same manner as in Example 1. Table 1 shows the results. Comparative Examples 1 to 3 The resin composition was blended according to the formulation shown in Table 1 to obtain a resin composition in the same manner as in Example 1, and evaluated in the same manner as in Example 1. Table 1 shows the results. The epoxy resin of the formula (4) (melting point 105 ° C.) used in Comparative Example 3 is shown below.

Embedded image

[0020]

[Table 1]

[0021]

Industrial Applicability The epoxy resin composition of the present invention is excellent in quick-curing properties, moldability, particularly excellent burrs characteristics and storage stability, and a semiconductor device using the same has excellent package crack resistance, even after long-term moisture absorption. No package crack

Claims (5)

[Claims] 1. A mixture of a stilbene type epoxy resin represented by the general formula (1) and a stilbene type epoxy resin represented by the general formula (2), and (B) two phenolic hydroxyl groups in one molecule. At least one of the phenolic resin having the above, (C) tetraphenylphosphonium tetranaphthoyloxyborate, (D) triphenylphosphine, 1,8-diazabicyclo (5,4,0) undecene-7, or 2-methylimidazole One, and (E)
The inorganic filler is an essential component, 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, and the blending amount of the inorganic filler (E) is all epoxy resins and all phenols. An epoxy resin composition characterized by being 200 to 2400 parts by weight per 100 parts by weight of the total amount of the resin. Embedded image (Wherein, R _{1 to} R ₈ each independently represent 1 to 6 carbon atoms)
Represents a chain or cyclic alkyl group, a hydrogen atom or a halogen atom. The two aryl groups attached to the carbon-carbon double bond are different from each other. ) (Where R _{9 to} R ₁₂ each independently represent a carbon number of 1 to
6 represents a chain or cyclic alkyl group, a hydrogen atom, or a halogen atom. The two aryl groups attached to the carbon-carbon double bond are the same as each other. ) 2. The epoxy resin according to claim 1, wherein the melting point of a mixture of the stilbene type epoxy resin represented by the general formula (1) and the stilbene type epoxy resin represented by the general formula (2) is 150 to 50 ° C. Composition. 3. The stilbene type epoxy resin represented by the general formula (1) is 4,4′-bis (2,3-epoxypropoxy) -5-
Tert-butyl-2,3 ', 5'-trimethylstilbene or 4,4'-bis (2,3-epoxypropoxy) -3-tert-butyl-3', 5,5'-trimethylstilbene, generally Equation (2)
The stilbene epoxy resin represented by 4,4'-bis (2,
3-epoxypropoxy) -3,3 ', 5,5'-tetramethylstilbene, 4,4'-bis (2,3-epoxypropoxy) -3,3'-ditert-butyl-6,6'-dimethyl Stilbene or 4,4'-
3. The epoxy resin composition according to claim 1, which is bis (2,3-epoxypropoxy) -3,3'-ditert-butyl-5,5'-dimethylstilbene. 4. A mixture of a stilbene type epoxy resin represented by the general formula (1) and a stilbene type epoxy resin represented by the general formula (2) is 4,4′-bis (2,3-epoxypropoxy)- 20 to 60% by weight of 5-tert-butyl-2,3 ', 5'-trimethylstilbene and 4,4'-bis (2,3-epoxypropoxy) -3,3', 5,5'-tetramethyl Stilbene 40-80
4. The epoxy resin composition according to claim 1, wherein the epoxy resin composition is composed of a weight percent. 5. A semiconductor device encapsulated with the epoxy resin composition according to claim 1, 2, 3, or 4.