JP2003040981A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition for semiconductor sealing which is excellent in flame retardancy, moldability and soldering crack resistance without using the conventional flame retardants. SOLUTION: The composition is characterized in that an epoxy resin of formula (1), (B) a phenolic resin of formula (2), (C) one or more sorts of phenolic resin selected from a group of phenolic resins of formulae (3) to (5), a curing promoter and an inorganic filler are essential components and a weight ratio of (B) to (C), [(B)/(C)], is 1-10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor encapsulating epoxy resin composition having excellent solder crack resistance and a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, electronic parts such as diodes, transistors and integrated circuits have been sealed mainly with an epoxy resin composition. Especially in integrated circuits, epoxy resin,
An epoxy resin composition having excellent heat resistance and moisture resistance, which is a mixture of a phenol resin and an inorganic filler such as fused silica or crystalline silica, is used. However, in recent years, in the market trend of miniaturization, weight reduction, and high performance of electronic devices, semiconductor elements have been highly integrated year by year, and surface mounting of semiconductor devices has been promoted. The demands on the epoxy resin composition used are becoming increasingly severe. Particularly in the current situation where surface mounting of semiconductor devices is becoming common, the absorbed semiconductor device is exposed to high temperature during solder reflow processing, and peels off at the interface between the semiconductor element or lead frame and the cured product of the epoxy resin composition. Occurs, resulting in cracks in the semiconductor device, which greatly impair the reliability of the semiconductor device, and prevention of these defects, that is, improvement of solder crack resistance is a major issue.

Furthermore, as part of the elimination of environmentally hazardous substances,
Replacement of lead-free solder is underway. Since the solder containing no lead has a higher melting point than the conventional solder, the reflow temperature during surface mounting is about 20 ° C. higher than that of the conventional solder.
0 ° C is required. By changing the solder reflow temperature for soldering that does not contain lead, peeling at the interface between the cured product of the epoxy resin composition and the pad, and peeling at the interface between the semiconductor element and the semiconductor resin paste The problem of cracks has arisen. These solder cracks and peeling are considered to occur when the semiconductor device itself before the solder reflow process absorbs moisture, and the moisture thereof causes a steam explosion at a high temperature during the solder reflow process. A method of imparting low hygroscopicity to a composition is often used, and as one of the methods of lowering the hygroscopicity, for example, an epoxy resin represented by the general formula (1) of low hygroscopicity and a general formula of low hygroscopicity are used. There is a method of reducing the moisture absorption of a cured product of an epoxy resin composition by using the phenol resin represented by (2). However, even an epoxy resin composition using a low hygroscopic resin component has been insufficient as an epoxy resin composition compatible with lead-free solder. Therefore, various improvements have been made for the purpose of improving the solder crack resistance at the time of surface mounting at 260 ° C. However, none of them is a complete solution and further improvement is desired.

In addition, in the epoxy resin composition, a halogen-based flame retardant such as a bromine-containing compound for imparting flame retardancy,
And an antimony compound. In recent years, there has been a movement to reduce or eliminate substances that may be harmful due to the importance of corporate activities that consider the global environment. Epoxy resin compositions with excellent flame retardancy without using halogen-based flame retardants or antimony compounds. Development is required. Epoxy resin compositions containing metal hydroxides such as aluminum hydroxide and magnesium hydroxide and red phosphorus have been proposed as environmentally friendly flame retardants to replace these, but epoxy resin compositions containing these flame retardants are proposed. There is a problem in that the epoxy resin composition that can reduce the moisture resistance reliability and the high temperature storage property of the semiconductor device using is not obtained, and further, the moldability and the curability are not sufficiently satisfied. I couldn't.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides an epoxy resin composition for semiconductor encapsulation which is excellent in moldability, and is excellent in flame retardancy without containing a conventional flame retardant, and is also excellent in solder crack resistance. An environment-friendly semiconductor device is provided.

[0006]

The present invention provides [1] (A) an epoxy resin represented by the general formula (1),
(B) Phenolic resin represented by the general formula (2), (C)
Phenolic resin represented by general formula (3), general formula (4)
A phenol resin represented by the formula (1), at least one phenol resin selected from the group of the phenol resins represented by the general formula (5), (D) a curing accelerator, and (E) an inorganic filler as essential components, ) And (C) weight ratio [(B) / (C)]
Is 1 to 10, and an epoxy resin composition for semiconductor encapsulation,

[Chemical 6] (R ₁ in the formula is a group selected from an alkyl group having 1 to 4 carbon atoms and may be the same or different from each other. M is an integer of 0 to 4 and n is an average value. (A positive number from 1 to 5)

[0007]

[Chemical 7] (R ₂ in the formula is a group selected from an alkyl group having 1 to 4 carbon atoms and may be the same or different from each other. M is an integer of 0 to 4 and n is an average value. (A positive number from 1 to 5)

[0008]

[Chemical 8] (R ₃ in the formula is a group selected from an alkyl group having 1 to 4 carbon atoms and may be the same as or different from each other. M is an integer of 0 to 4 and n is an average value. (A positive number from 1 to 5)

[0009]

[Chemical 9] (In the formula, R ₄ is a group selected from an alkyl group having 1 to 4 carbon atoms and may be the same or different. M is an integer of 0 to 4 and n is an average value. (A positive number from 1 to 5)

[0010]

[Chemical 10] (In the formula, R ₅ is a group selected from an alkyl group having 1 to 4 carbon atoms and may be the same or different. M is an integer of 0 to 4 and n is an average value. A positive number from 1 to 5) [2] A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition according to the item [1].

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION General formula (1) used in the present invention
The epoxy resin represented by has two epoxy groups in one molecule.
It is characterized by having one or more and having a hydrophobic structure between each epoxy group. The cured product of the epoxy resin composition using the epoxy resin represented by the general formula (1) has a low moisture absorption rate because it contains many hydrophobic structures, and since the crosslink density is low, it is in a high temperature range exceeding the glass transition temperature. Has a low elastic modulus, reduces thermal stress during surface mounting soldering, and has excellent resistance to solder cracking and excellent adhesion to base materials such as lead frames after soldering. ing.
On the other hand, since the hydrophobic structure between the epoxy groups is a rigid biphenyl skeleton, it has a characteristic that the heat resistance is not significantly reduced despite the low crosslink density. The epoxy resin represented by the general formula (1) may be used alone or in combination of two or more. Specific examples of the epoxy resin represented by the general formula (1) are shown below, but the epoxy resin is not limited to these.

[Chemical 11] (N in the formula is an average value and is a positive number of 1 to 5)

Other epoxy resins may be used in combination as long as the characteristics of the epoxy resin represented by the general formula (1) are not impaired. Epoxy resins that can be used in combination include all monomers, oligomers, and polymers having an epoxy group in the molecule. For example, phenol novolac type epoxy resin, orthocresol novolac type epoxy resin, naphthol novolac type epoxy resin, phenol aralkyl type epoxy resin having a phenylene skeleton, naphthol aralkyl type epoxy resin (having a phenylene skeleton, biphenyl skeleton, etc.), dicyclopentadiene Modified phenol type epoxy resin, stilbene type epoxy resin, triphenol methane type epoxy resin, alkyl modified triphenol methane type epoxy resin, triazine nucleus-containing epoxy resin and the like can be mentioned. These are two or more kinds even if one kind is used alone. You may use together. The content of the epoxy resin represented by the general formula (1) is preferably 70% by weight or more based on the total epoxy resin. If it is less than 70% by weight, it is easy to burn, the moisture absorption is high, and the elastic modulus is high, so that the solder crack resistance may be deteriorated.

The phenol resin represented by the general formula (2) used in the present invention is characterized by having two or more phenolic hydroxyl groups in one molecule and having a hydrophobic structure between each phenolic hydroxyl group. . A cured product of an epoxy resin composition using a phenol resin represented by the general formula (2) has a low moisture absorption rate because it contains many hydrophobic structures, and also has a low crosslink density, so that it is in a high temperature range exceeding the glass transition temperature. Has a low elastic modulus, reduces thermal stress at the time of surface mounting soldering, and has excellent solder crack resistance and adhesion to a base material after soldering. on the other hand,
Since the hydrophobic structure between the phenolic hydroxyl groups is a rigid biphenyl skeleton, it has a characteristic that the heat resistance is not significantly reduced despite the low crosslink density. The phenol resin represented by the general formula (2) may be used alone or in combination of two or more kinds. Specific examples of the phenol resin represented by the general formula (2) are shown below, but the invention is not limited thereto.

[Chemical 12] (N in the formula is an average value and is a positive number of 1 to 5)

Recent lead-free solder compatible materials include:
It is often difficult to sufficiently deal with the problem by using only the phenol resin represented by the general formula (2). Further, the phenol resin represented by the general formula (3) and the general formula (4) used in the present invention are represented. It is preferable to use at least one selected from the group consisting of a phenol resin and a phenol resin represented by the general formula (5). When the low-viscosity / low-molecular-weight / high-strength phenol resin represented by the general formulas (3) to (5) is used in combination with the phenol resin represented by the general formula (2), Since the epoxy resin composition has a lower melt viscosity when heated than the epoxy resin composition using only the indicated phenol resin, the flowability of the epoxy resin composition is improved, and the inorganic filler is further highly filled. It is possible to further lower the moisture absorption of the cured product of the epoxy resin composition, and further to obtain higher strength. The crack of the semiconductor device that occurs during the solder reflow treatment is caused by peeling at the interface between the cured product of the epoxy resin composition and the lead frame or at the interface between the cured product of the epoxy resin composition and the semiconductor element, By obtaining a low moisture absorption, high strength epoxy resin composition,
These peelings are reduced, and the solder crack resistance of the semiconductor device can be significantly improved. Further like the present invention,
When the epoxy resin represented by the general formula (1), the phenol resin represented by the general formula (2), and the phenol resin represented by the general formulas (3) to (5) are used in combination, solder treatment after moisture absorption is performed. In terms of solder crack resistance, flame retardancy, etc., the highest effect can be obtained. From the group of the phenol resin (B) represented by the general formula (2), the phenol resin represented by the general formula (3), the phenol resin represented by the general formula (4), and the phenol resin represented by the general formula (5) Weight ratio [(B) / (C)] with one or more selected (C)
Is preferably 1 to 10. When it is less than 1, the cured product of the epoxy resin composition cannot have low moisture absorption and the flame retardancy of the cured product is deteriorated. On the other hand, when it is more than 10, the inorganic filler cannot be highly filled and the moisture absorption becomes low. It is not preferable because high strength cannot be achieved. When two or more phenol resins represented by the general formulas (3) to (5) are used in combination, they may be mixed or melt-mixed in advance.

Further, in the present invention, another phenol resin is used in combination with the phenol resin represented by the general formula (2) and the phenol resin represented by the general formulas (3) to (5) without impairing the characteristics. You may. Examples of the phenol resin that can be used in combination include monomers, oligomers and polymers having a phenolic hydroxyl group in the molecule. For example, naphthol aralkyl resin (having a biphenyl skeleton, etc.), terpene-modified phenol resin, dicyclopentadiene-modified phenol resin, bisphenol A, triphenol methane type resin, etc. can be mentioned. You may use together the above. At least one selected from the group consisting of a phenol resin represented by the general formula (3), a phenol resin represented by the general formula (4), and a phenol resin represented by the general formula (5), and a general formula (2). The total amount of the phenol resin and the total amount of the phenol resin used is preferably 70% by weight or more based on the total phenol resin. If it is less than 70% by weight, it is easy to burn, the moisture absorption is high, and the elastic modulus is high, so that the solder crack resistance may be deteriorated. As the ratio (equivalent ratio) of the number of epoxy groups in the total epoxy resin and the number of phenolic hydroxyl groups in the total phenolic resin, (the number of epoxy groups) / (the number of phenolic hydroxyl groups) = 0.7 to 1.5 is preferable, and this range If it is out of the range, the curability of the epoxy resin composition may be lowered, the glass transition temperature of the cured product may be lowered, or the moisture resistance reliability may be lowered.

The curing accelerator used in the present invention includes:
Any material that accelerates the curing reaction between the epoxy group and the phenolic hydroxyl group may be used, and those generally used for sealing materials may be widely used. For example, tributylamine, 1,8-diazabicyclo (5,4,0) undecene-7 and other diazabicycloalkenes and derivatives thereof, amine compounds such as tributylamine and benzyldimethylamine, tetraphenylphosphonium tetranaphthoic acid Examples thereof include, but are not limited to, organic phosphorus compounds such as borate and triphenylphosphine, imidazole compounds such as 2-methylimidazole, and the like. These curing accelerators may be used alone or in combination of two or more. Of these, 1,8-diazabicyclo (5,4,0) undecene-7 is particularly effective for improving the adhesion to various substrates, and tetraphenylphosphonium / tetranaphthoic acid borate is It has the effect of significantly improving the room temperature storage characteristics of the epoxy resin composition.

The inorganic filler used in the present invention includes:
A wide range of materials generally used as sealing materials can be used, for example, fused silica, spherical silica, crystalline silica, secondary agglomerated silica, porous silica, secondary agglomerated silica or silica obtained by pulverizing porous silica. , Alumina, silicon nitride and the like, but are not limited thereto.
These may be used alone or in combination of two or more. In particular, fused silica and crystalline silica are preferable. The shape of the inorganic filler may be crushed or spherical, but spherical fused silica is used from the viewpoint of high filling to improve solder crack resistance and the balance of fluidity, mechanical strength and thermal properties. Is preferred. 75 as the maximum particle size
The average particle size is preferably 5 to 25 μm. A broad particle size distribution is effective for reducing the melt viscosity of the epoxy resin composition during molding. Further, a surface-treated material such as a silane coupling agent may be used. The blending amount of the inorganic filler is preferably 65 to 95% by weight in the total epoxy resin composition.
If it is less than 65% by weight, the moisture absorption of the cured product of the epoxy resin composition increases and the strength at the solder processing temperature decreases, so that the semiconductor device is apt to crack during the solder processing. When the content exceeds the weight%, the fluidity of the epoxy resin composition at the time of molding is lowered, and there is a possibility that unfilling or pad shift of a semiconductor element is likely to occur. If the inorganic filler is blended as much as possible, the moisture absorption rate of the cured product of the epoxy resin composition will be decreased and the solder crack resistance will be improved, so the blending amount was as much as possible within the range in which the fluidity during molding is allowed. Is preferred.

The epoxy resin composition of the present invention comprises (A)-
In addition to the component (E), a halogen-containing flame retardant such as a brominated epoxy resin and an antimony compound such as antimony oxide may be contained, if necessary.
For applications requiring stability of electrical properties at high temperatures of 50 to 260 ° C., the content of halogen atoms and antimony atoms is preferably 0.1% by weight or less in the total epoxy resin composition, and Is more preferably not included in. Either halogen atom or antimony atom is 0.1
If it exceeds 5% by weight, the resistance value of the semiconductor device increases with time when left at a high temperature, and finally, there is a possibility that the gold wire of the semiconductor element is broken. Also, from the viewpoint of environmental protection, it is desirable that the content of each of halogen atoms and antimony atoms is 0.1% by weight or less, and the content thereof is as small as possible.

The epoxy resin composition of the present invention comprises (A)-
In addition to the component (E), if necessary, an inorganic ion exchanger such as bismuth oxide hydrate, a coupling agent such as γ-glycidoxypropyltrimethoxysilane, a coloring agent such as carbon black and red iron oxide, a silicone oil, It is possible to add various additives such as a stress reducing component such as silicone rubber, a natural wax, a synthetic wax, a releasing agent such as higher fatty acids and their metal salts or paraffin, and an antioxidant. The epoxy resin composition of the present invention is obtained by mixing components (A) to (E), other additives, etc. at room temperature using a mixer or the like, heating and kneading with a kneader such as a roll, kneader or extruder, and cooling. It is obtained by crushing afterwards. The epoxy resin composition of the present invention is a transistor that is an electric component or an electronic component,
It can be applied to covering, insulating, sealing, etc. of integrated circuits. In order to manufacture a semiconductor device by sealing an electronic component such as a semiconductor element using the epoxy resin composition of the present invention, molding and curing may be performed by a molding method such as a transfer mold, a compression mold or an injection mold.

[0020]

The present invention will be described in detail below with reference to examples of the present invention, but the present invention is not limited thereto. The mixing ratio of each component is% by weight. <Example 1> Epoxy resin a represented by the formula (12) (softening point 60 ° C., ICI melt viscosity at 150 ° C. 0.8 × 10 ² mPa · s, epoxy equivalent 270) 5.80% by weight

[Chemical 13]

4.20% by weight of a phenolic resin c represented by the formula (13) (softening point of 65 ° C., ICI at 150 ° C., melt viscosity of 1.0 × 10 ² mPa · s, hydroxyl group equivalent of 203)

[Chemical 14]

Phenolic resin d represented by the formula (14) (softening point 60 ° C., ICI at 150 ° C. melt viscosity 0.7 × 10 ² mPa · s, hydroxyl group equivalent 162) 0.50% by weight

[Chemical 15] 1,8-Diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) 0.20% by weight Spherical fused silica (average particle size 22 μm) 88.00% by weight carbon black 0.30% by weight Carnauba wax 0 30% by weight Other additives 0.70% by weight were mixed at room temperature with a mixer, kneaded with a roll at 70 to 110 ° C., cooled, pulverized, and tableted to obtain an epoxy resin composition. . This epoxy resin composition was evaluated by the following methods. The results are shown in Table 1.

Evaluation method-Spiral flow: Using a mold for spiral flow measurement according to EMMI-1-66, mold temperature 175
C., injection pressure 6.9 MPa, curing time 120 s. The unit is cm. -Hot bending strength-Hot bending elastic modulus: Using a low-pressure transfer molding machine, mold temperature 175 ° C, injection pressure 6.9M
The test piece was molded with Pa and a curing time of 120 s, and after being post-cured at 175 ° C. for 8 hours, the bending strength under heat,
Alternatively, the bending elastic modulus at the time of heating was measured according to JIS K 6911 (at 260 ° C.). The unit is N / mm ² . Moisture absorption rate: Using a low-pressure transfer molding machine, mold temperature 175 ° C, injection pressure 6.9 MPa, curing time 120 s to mold a disc-shaped test piece with a diameter of 50 mm and a thickness of 3 mm, and post-cure for 8 hours at 175 ° C. Processed. 16 before the moisture absorption treatment of the test piece and under the environment of 85 ° C and relative humidity of 85%
The weight change after moisture absorption treatment for 8 hours was measured, and the moisture absorption rate of the test piece was shown in percentage. Units%. Solder crack resistance: 160 pLQFP (thickness 1.4 mm, chip size 7 mm × 7 mm) was molded using a low-pressure transfer molding machine at a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 120 s. As a post cure, 85 packages of 5 packages treated at 175 ° C for 8 hours
After processing for 168 hours in an environment of ℃ and 60% relative humidity,
IR reflow treatment (260 ° C.) was performed. Observe the presence or absence of internal peeling or cracks after treatment with an ultrasonic flaw detector,
Counted the number of defective packages. When the number of defective packages is n, it is displayed as n / 5. -Flame resistance: Using a low-pressure transfer molding machine, mold temperature 175 ° C, injection pressure 6.9 MPa, curing time 120 s
After the test piece was molded by the above method and treated as post cure at 175 ° C. for 8 hours, the UL-94 vertical test (test piece thickness 1/8
Inch) was performed to determine the flame retardancy.

<Examples 2 to 8 and Comparative Examples 1 to 13> Materials used in other than Example 1 are shown below. Phenolic resin e
(A phenol resin represented by the formula (14) and a phenol resin represented by the formula (15) are melted. Softening point 65
ICI melt viscosity at 70 ℃ and 150 ℃ 0.7 × 10 ² mPa
・ S, hydroxyl equivalent 140),

[Chemical 16]

Phenolic resin f represented by the formula (15)
(Softening point 75 ° C, ICI melt viscosity at 150 ° C 0.6 ×
10 ² mPa · s, hydroxyl group equivalent 112), phenol resin g represented by the formula (16) (softening point 70 ° C., ICI melt viscosity at 150 ° C. 0.7 × 10 ² mPa · s, hydroxyl group equivalent 170),

[Chemical 17]

Epoxy resin b containing a compound represented by the formula (17) as a main component (ICI at melting points of 105 ° C. and 150 ° C.)
Melt viscosity 0.2 × 10 ² mPa · s, Epoxy equivalent 18
5).

[Chemical 18]

Epoxy resin compositions were obtained in the same manner as in Example 1 according to the formulations shown in Tables 1 and 2 and evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[Table 1]

[0028]

[Table 2]

[0029]

According to the present invention, an epoxy resin composition for semiconductor encapsulation which is excellent in flame retardancy and moldability can be obtained without using a conventional flame retardant. An excellent semiconductor device can be obtained.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 23/29 H01L 23/30 R 23/31 F term (reference) 4J002 CC04X CC043 CC053 CD06W DE147 DJ007 DJ017 EN026 EU116 EU136 EW136 EW176 FA087 FD017 FD090 FD14X FD143 FD156 FD160 GQ05 4J033 CA02 CA05 CA09 CA11 CA12 CA22 CA28 4J036 AF06 AF36 DA02 DA06 DC05 DC06 DC40 DC46 DD07 FA01 FB08 GA04 JA07 4M109 AA01 BA01 CA21 CA22 EA03 EB03 EB04 EB06 EB07 EB08 EB09 EB13 EB18 EB19 EC03 EC20

Claims (2)

[Claims] 1. An epoxy resin represented by the general formula (1) (A), a phenol resin represented by the general formula (2) (B),
(C) at least one phenol resin selected from the group consisting of a phenol resin represented by the general formula (3), a phenol resin represented by the general formula (4), and a phenol resin represented by the general formula (5); ) A curing accelerator and (E) an inorganic filler are essential components, and the weight ratio of (B) to (C) [(B) /
(C)] is 1 to 10. An epoxy resin composition for semiconductor encapsulation. [Chemical 1] (R ₁ in the formula is a group selected from an alkyl group having 1 to 4 carbon atoms and may be the same or different from each other. M is an integer of 0 to 4 and n is an average value. Positive number from 1 to 5). [Chemical 2] (R ₂ in the formula is a group selected from an alkyl group having 1 to 4 carbon atoms and may be the same or different from each other. M is an integer of 0 to 4 and n is an average value. Positive number from 1 to 5). [Chemical 3] (R ₃ in the formula is a group selected from an alkyl group having 1 to 4 carbon atoms and may be the same as or different from each other. M is an integer of 0 to 4 and n is an average value. Positive number from 1 to 5). [Chemical 4] (In the formula, R ₄ is a group selected from an alkyl group having 1 to 4 carbon atoms and may be the same or different. M is an integer of 0 to 4 and n is an average value. Positive number from 1 to 5) (In the formula, R ₅ is a group selected from an alkyl group having 1 to 4 carbon atoms and may be the same or different. M is an integer of 0 to 4 and n is an average value. (A positive number from 1 to 5) 2. A semiconductor device obtained by encapsulating a semiconductor element using the epoxy resin composition according to claim 1.