JP3230771B2 - Resin composition for semiconductor encapsulation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin composition for encapsulating a semiconductor having excellent resistance to soldering stress and moisture.

[0002]

2. Description of the Related Art Conventionally, electronic components such as diodes, transistors, and integrated circuits are sealed with a thermosetting resin. In particular, in an integrated circuit, an O-cresol novolak epoxy resin having excellent heat resistance and moisture resistance is made of novolak. Epoxy resin compositions cured with a type phenolic resin have been used. However, in recent years, in the market trend of miniaturization, weight reduction and high performance of electronic devices, high integration of semiconductors is progressing year by year, and small and thin surface mount type packages are becoming mainstream. The demand for the sealing resin is becoming increasingly severe due to the increase in size of the chip accompanying the development of the semiconductor device, and it has become difficult to secure the reliability of the conventional resin composition. This is because the semiconductor mounting method changes from the conventional pin insertion type to the surface mounting type (VPS reflow type, IR reflow type, solder immersion method, etc.)
, The solder immersion process suddenly becomes 20
Exposure to a high temperature of 0 ° C or higher may cause the package to crack, peel off the interface between the chip and the sealing resin, degrade moisture resistance, and reduce reliability. This is because the influence is further increased. Under such circumstances, development of a highly reliable resin having excellent crack resistance and moisture resistance even under severe conditions such as solder immersion is urgently required.

In order to solve these problems, addition of thermoplastic oligomers (Japanese Patent Laid-Open No. 62-15849) and addition of various silicone compounds (Japanese Patent Laid-Open No. 62-15849) have been proposed for the purpose of reducing thermal shock during soldering. No. 11585, 62-
116654, 62-128162) and silicone modification (Japanese Patent Application Laid-Open No. 62-136860), all of which have cracks in the package during solder immersion and have excellent reliability. It has not been possible to obtain an epoxy resin composition for semiconductor encapsulation.
On the other hand, in order to obtain an epoxy resin composition for semiconductor encapsulation having excellent resistance to solder cracking during solder immersion, a phenol aralkyl resin is used as a curing agent (JP-A-59-6766).
No. 0) has been studied, but the use of a phenol aralkyl resin improves the adhesion to the lead frame and low water absorption, and reduces the occurrence of cracks. temperature,
It has a drawback that it is significantly lower than the conventional phenol novolak curing agent system and has poor long-term heat resistance.

[0004]

An object of the present invention is to provide a resin composition for semiconductor encapsulation which is remarkably excellent in solder crack resistance, moisture resistance and heat resistance against such problems.

[0005]

Means for Solving the Problems The present inventors have intensively studied to solve these problems and found a resin composition having the following composition. That is, the present invention relates to (A) an epoxy resin, (B) a curing agent containing 50 to 100% by weight of a phenol resin compound represented by the chemical structural formula (1) based on the total curing agent amount, as a curing agent;

[0006]

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[0007] (C) an inorganic filler as an essential component,
The resin composition for semiconductor encapsulation wherein the inorganic filler is 70 to 90% by weight of the total composition. As the epoxy resin (A) used in the present invention, various epoxy resins such as bisphenol type, phenol novolak type, orthocresol novolak type, trisphenylmethane type and naphthalene skeleton-containing type can be applied. No problem,
In particular, when the biphenyl type epoxy represented by the formula (2) is used, a large amount of an inorganic filler can be blended without impairing the fluidity because the melt viscosity of the epoxy resin itself is low, and thus the high strength and low moisture absorption resistance can be obtained. A resin composition having excellent solder stress properties can be obtained.

[0008]

Embedded image (R ₁ , R ₂ , R ₃ and R ₄ are H or CH ₃ )

When using a biphenyl type epoxy, it is desirable to use 50% by weight or more, preferably 70% by weight or more based on the total amount of epoxy. If it is less than 50% by weight, the viscosity of the resin cannot be reduced, and it is difficult to mix a large amount of the desired inorganic filler.

The phenol resin curing agent having the structure represented by the formula (1) has the following two features. First
Is that the compound has a cycloalkane represented by X in the molecular chain, and has an effect of being excellent in moisture resistance and excellent in flexibility when heated compared to a conventional phenol novolak resin. . When cycloalkanes having such a flexible structure are incorporated into the molecule, the reactivity is lowered, and the crosslink density of the cured product is lowered, so that the glass transition temperature is lowered. Thus, the second point is to incorporate a phenolic hydroxyl group into the molecular side chain, which has the effect of improving the reactivity and the glass transition temperature. The value of n in the formula (1) is from 1 to 8, and if it exceeds 8, the fluidity decreases and the moldability deteriorates. X in the formula (1) is
They may be used alone or as a mixture of two types. By adjusting the amount of the phenol resin curing agent used, solder crack resistance can be maximized. In order to obtain the effect of solder crack resistance, the phenolic resin curing agent represented by the formula (1) is used in an amount of 50% by weight or more, preferably 70% by weight of the total amount of the phenolic resin curing agent.
The above use is desirable. If the amount is less than 50% by weight, low moisture absorption and flexibility under heat cannot be obtained, and the solder crack resistance is insufficient.

When another phenolic resin-based curing agent is used in addition to the modified phenolic resin-based curing agent represented by the formula (1), the phenolic resin-based curing agent used refers to all compounds having a phenolic hydroxyl group. For example, bisphenol A, bisphenol F, phenol novolak resin,
Cresol novolak resin, phenol aralkyl resin and the like can be used. These phenolic resins used in combination are appropriately used for the purpose of adjusting curability, imparting flexibility, etc., but for adjusting fluidity, low molecular weight compounds such as bisphenol F and narrow low molecular weight phenol novolak resins are suitable. .

The inorganic filler used in the present invention includes fused silica powder, crystalline silica powder, alumina powder, hydrated alumina powder, silicon nitride powder, calcium carbonate powder, and the like, with fused silica powder being particularly preferred. The amount of the inorganic filler is preferably in the range of 70 to 90% by weight. 70% by weight
In the following cases, the amount of moisture absorption is large, and the coefficient of thermal expansion is too large to withstand thermal stress during mounting. 90% by weight
Above this, the flow characteristics deteriorate, making it impractical.

The epoxy resin composition for sealing of the present invention comprises an epoxy resin, a curing agent and an inorganic filler as essential components.
In addition, if necessary, a curing accelerator, a silane coupling agent, a brominated epoxy resin, a flame retardant such as antimony trioxide, hexabromobenzene, a coloring agent such as carbon black or red iron, a natural wax, a synthetic wax, etc. Various additives such as a mold agent and low stress additives such as silicone oil and rubber may be appropriately compounded. Further, in order to produce the sealing epoxy resin composition of the present invention as a molding material, an epoxy resin, a curing agent, a curing accelerator, a filler,
After sufficiently mixing other additives with a mixer or the like, the mixture is further melt-mixed with a hot roll or a kneader or the like, cooled and pulverized to obtain a molding material. These molding materials can be applied to sealing, coating, insulating and the like of electronic parts or electric parts.

[0014]

The present invention will be described below by way of examples. The mixing ratio is by weight. Examples 1 to 6, Comparative Examples 1 to 4 (A) Epoxy resin ortho-cresol novolak type epoxy resin (epoxy equivalent 200, softening point 65 ° C) Biphenyl type epoxy: 3,3 ', 5,5'-tetramethyl-4 4,4'-dihydroxybiphenyl glycidyl ether (epoxy equivalent 195) (B) phenol resin curing agent A phenol resin represented by the formula (3) (hydroxyl equivalent 1
75, softening point 80 ° C)

[0015]

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A phenol resin represented by the formula (4) (hydroxyl equivalent 180, softening point 80 ° C.)

[0017]

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Phenol novolak resin (hydroxyl equivalent 105, softening point 80 ° C.) Phenol aralkyl resin represented by the formula (5) (hydroxyl equivalent 180, softening point 80 ° C.)

[0019]

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(C) Inorganic filler Fused silica powder (average particle size: 14 μm) (D) Other raw materials Curing accelerator: triphenylphosphine Release agent: carnauba wax at room temperature in a mixer at the respective ratios shown in Table 1. The mixture was mixed, kneaded with a biaxial roll at 70 to 100 ° C., cooled and pulverized to obtain a molding material, which was tabletted to obtain an epoxy resin composition for semiconductor encapsulation. A low-pressure transfer molding machine (molding conditions: 175 ° C., 70 kg / c)
m ² , 120 seconds).
Post-curing was performed at 5 ° C. for 8 hours and evaluated. Table 1 shows the results.

Evaluation method * 1 Spiral flow Using a mold for spiral flow observation in accordance with EMMI-I-66, mold temperature 175 ° C, injection pressure 70 kg / cm ² ,
Measured with a curing time of 2 minutes. * 2 Curability Using a Shore D hardness meter, mold temperature 175 ° C, curing time 2
Measured in minutes. * 3 Heat resistance The glass transition temperature of the cured product was determined by measuring the thermal expansion characteristics of a test piece molded at 175 ° C. for 2 minutes and post-cured at 175 ° C. for 8 hours. * 4 Solder cracking test 85 molded products (chip size 6 × 6 mm, 52pQFP)
After 48 hours and 72 hours of treatment in an environment of 85 ° C. and 85% RH, the wafer was immersed in a solder bath at 260 ° C. for 10 seconds, and external cracks were observed with a microscope. * 5 Solder moisture resistance test Molded product (chip size 3 x 6 mm simulation element, 16 pSO
P) is treated for 72 hours in an environment of 85 ° C. and 85% RH,
Then, after dipping in a solder bath at 260 ° C. for 10 seconds, a pressure cooker test (125 ° C., 100% RH) was performed to measure the number of open defects of the circuit.

[0022]

[Table 1]

[0023]

According to the present invention, it is possible to obtain an epoxy resin composition having soldering stress resistance, which cannot be obtained by the prior art. When used for encapsulation, coating, insulation, etc. of electronic and electrical components, especially for highly integrated large chip ICs mounted on surface mount packages because of their excellent crack resistance and excellent moisture resistance It is suitable for products that require extremely high reliability.

Continuation of the front page (51) Int.Cl. ⁷ identification code FI H01L 23/31 (58) Fields investigated (Int.Cl. ⁷ , DB name) C08G 59/62 C08G 59/24 C08L 63/00-63 / 10 H01L 23/29

Claims (2)

(57) [Claims] 1. A curing agent containing (A) an epoxy resin, (B) a phenolic resin compound represented by the chemical structural formula (1) as a curing agent in an amount of 50 to 100% by weight based on the total amount of the curing agent, and Formula 1 (C) An inorganic filler is an essential component, and (C) 70 to 90% by weight of the inorganic filler in the total composition is a resin composition for semiconductor encapsulation. 2. The semiconductor encapsulation according to claim 1, wherein (A) the epoxy resin is a biphenyl type epoxy represented by the formula (2) and the amount of the epoxy resin is 50 to 100% by weight based on the total amount of the epoxy resin. Resin composition. Embedded image (R ₁ , R ₂ , R ₃ and R ₄ are H or CH ₃ )