JPH06157725A - Resin composition for sealing semiconductor - Google Patents

Abstract

PURPOSE:To obtain the subject composition composed of an epoxy resin, a specific curing agent and an inorganic filler at specific ratios and having excellent soldering crack resistance, moisture resistance and heat resistance. CONSTITUTION:The objective composition contains (A) an epoxy resin containing 50-100wt.% (based on the total epoxy resin) of a biphenyl-type epoxy resin of formula I (R1 to R4 are H or CH3), (B) a curing agent containing 50-100wt.% (based on the total curing agent) of a phenol resin compound of formula II (X is group of formula II or formula III; (n) is 1-8) as curing agent and (C) 70-90wt.% (based on the total composition) of an inorganic filler such as fused silica powder.

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 semiconductor encapsulation having excellent solder stress resistance and moisture resistance.

[0002]

2. Description of the Related Art Conventionally, electronic parts such as diodes, transistors and integrated circuits have been sealed with a thermosetting resin. Especially in integrated circuits, O-cresol novolac epoxy resin which is excellent in heat resistance and moisture resistance is used as a novolac resin. Epoxy resin compositions that have been cured with type phenolic resins have been used. However, due to the recent market trend of miniaturization, weight reduction and high performance of electronic equipment, the high integration of semiconductors is advancing year by year, and small and thin surface mounting type is becoming the mainstream in the package. Due to the increase in size of chips accompanying the increase in demand, the demand for sealing resin has become more and more severe, and it has become difficult to secure reliability with conventional resin compositions. This is a semiconductor mounting method from the conventional pin insertion type to surface mounting type (VPS reflow type, IR reflow type, solder dipping method, etc.)
By changing to the
This is because the package is cracked due to exposure to high temperatures of 0 ° C or higher, and the interface between the chip and the encapsulation resin peels off, resulting in deterioration of moisture resistance and reduced reliability. This is because the influence will be even greater. Under such circumstances, there is an urgent need to develop a highly reliable resin having excellent crack resistance and moisture resistance even under severe conditions such as solder immersion.

In order to solve these problems, in order to alleviate the thermal shock at the time of soldering, addition of a thermoplastic oligomer (Japanese Patent Laid-Open No. 62-15849) and addition of various silicone compounds (Japanese Patent Laid-Open No. 62- 11585, 62-
No. 116654, 62-128162) and further silicone modification (Japanese Patent Laid-Open No. 62-136860), but all of them are excellent in reliability because cracks are generated in the package during solder immersion. 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 which is excellent in solder crack resistance during solder immersion, use of a phenol aralkyl resin as a curing agent (Japanese Patent Laid-Open No. 59-6766).
No. 0) has been studied, but by using a phenol aralkyl resin, the adhesion to the lead frame and low water absorption are improved, and cracking is reduced, but in the phenol aralkyl resin curing agent system, the glass transition of the cured product temperature,
Compared with the conventional phenol novolac curing agent system, it has a remarkably low level and has a drawback that the long-term heat resistance is inferior.

[0004]

SUMMARY OF THE INVENTION The present invention provides a resin composition for encapsulating a semiconductor, which is extremely excellent in solder crack resistance, moisture resistance and heat resistance against such problems.

[0005]

[Means for Solving the Problems] The inventors of the present invention have conducted extensive studies 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 a phenol 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,

[0006]

[Chemical 3]

(C) Inorganic filler as an essential component, (C)
It is a resin composition for semiconductor encapsulation in which the inorganic filler is 70 to 90% by weight in the whole composition. As the epoxy resin (A) used in the present invention, various epoxy resins such as bisphenol type, phenol novolac type, orthocresol novolac type, trisphenylmethane type, and naphthalene skeleton-containing type can be applied, and even if two or more kinds are used in combination. It doesn't matter, but
In particular, when the biphenyl type epoxy represented by the formula (2) is used, the epoxy resin itself has a low melt viscosity, so that a large amount of an inorganic filler can be blended without impairing the fluidity, and by extension, a high strength and a low moisture absorption resistance. A resin composition having excellent solder stress properties can be obtained.

[0008]

[Chemical 4] (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 lowered and it is difficult to mix a large amount of the desired inorganic filler.

The characteristics of the phenol resin curing agent having the structure represented by the formula (1) include the following two points. First
The point is that it has a cycloalkane represented by X in the molecular chain, and has an effect that it is superior in moisture resistance and is excellent in flexibility when heated, as compared with the conventional phenol novolac resin. . When cycloalkanes having such a flexible structure are incorporated into the molecule, the reactivity is lowered, and further, the crosslink density of the cured product is lowered, so that the glass transition temperature is lowered. Therefore, the second point is to incorporate a phenolic hydroxyl group into the side chain of the molecule, 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. Further, X in the formula (1) is
They may be used alone or as a mixture of two kinds. 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 phenol resin curing agent represented by the formula (1) is used in an amount of 50% by weight or more, preferably 70% by weight or more, based on the total amount of the phenol resin curing agent.
The above use is desirable. If it is less than 50% by weight, low hygroscopicity and flexibility during heating cannot be obtained, and the solder crack resistance is insufficient.

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

Examples of the inorganic filler used in the present invention include fused silica powder, crystalline silica powder, alumina powder, hydrated alumina powder, silicon nitride powder and calcium carbonate powder, and fused silica powder is particularly preferred. The content of the inorganic filler is preferably 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 large, so that it cannot withstand the thermal stress during mounting. 90% by weight
If it becomes the above, the flow characteristics will deteriorate and it will become impractical.

The epoxy resin composition for encapsulation of the present invention contains an epoxy resin, a curing agent and an inorganic filler as essential components.
In addition to these, curing accelerators, silane coupling agents, brominated epoxy resins, flame retardants such as antimony trioxide and hexabromobenzene, colorants such as carbon black and red iron oxide, natural wax, synthetic wax, etc. may be added as necessary. Various additives such as mold agents and low stress additives such as silicone oil and rubber may be appropriately blended. Further, in order to produce the encapsulating epoxy resin composition of the present invention as a molding material, an epoxy resin, a curing agent, a curing accelerator, a filler,
After other additives are sufficiently uniformly mixed with a mixer or the like, they are further melt-mixed with a hot roll or a kneader, cooled and pulverized to obtain a molding material. These molding materials can be applied to sealing, coating, insulating, etc. of electronic parts or electric parts.

[0014]

EXAMPLES The present invention will be described below with reference to examples. The mixing ratio is parts by weight. Examples 1 to 6 and Comparative Examples 1 to 4 (A) Epoxy resin Orthocresol novolac type epoxy resin (epoxy equivalent 200, softening point 65 ° C.) Biphenyl type epoxy: 3,3 ′, 5,5′-tetramethyl-4 , 4'-Dihydroxybiphenyl glycidyl ether (epoxy equivalent 195) (B) Phenolic resin curing agent Phenolic resin represented by the formula (3) (hydroxyl equivalent 1
75, softening point 80 ° C)

[0015]

[Chemical 5]

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

[0017]

[Chemical 6]

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

[0019]

[Chemical 7]

(C) Inorganic filler Fused silica powder (average particle size 14 μm) (D) Other raw materials Curing accelerator: triphenylphosphine Release agent: carnauba wax The mixture was mixed, kneaded with a biaxial roll at 70 to 100 ° C., cooled and pulverized to obtain a molding material, which was tableted to obtain an epoxy resin composition for semiconductor encapsulation. A low-pressure transfer molding machine (molding condition: 175 ° C., 70 kg / c)
m ² for 120 seconds) and the resulting molded product
It was post-cured at 5 ° C. for 8 hours and evaluated. The results are shown in Table 1.

Evaluation method * 1 Spiral flow Using a spiral flow observation mold according to EMMI-I-66, mold temperature 175 ° C., injection pressure 70 kg / cm ² ,
Measured at 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 A glass transition temperature of the cured product was determined by measuring the thermal expansion characteristics of a test piece which was molded under the conditions of 175 ° C. for 2 minutes and post-cured at 175 ° C. for 8 hours. * 4 Solder crack resistance test Molded product (chip size 6x6mm, 52pQFP) 85
After 48 hours and 72 hours of treatment in an environment of 85 ° C. and 85% RH, and after immersion in a solder bath at 260 ° C. for 10 seconds, external cracks were observed with a microscope. * 5 Solder moisture resistance test Molded product (chip size 3 x 6 mm simulated 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 in the circuit.

[0022]

[Table 1]

[0023]

According to the present invention, it is possible to obtain an epoxy resin composition having a soldering stress resistance which could not be obtained by the prior art. Therefore, when a thermal stress due to a rapid temperature change due to a soldering process is received. Has excellent crack resistance and good moisture resistance, so when used for encapsulation, coating, insulation, etc. of electronic and electrical parts, it is a highly integrated large chip IC mounted in a surface mount package. It is suitable for products that require extremely high reliability.

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 23/29 23/31

Claims (2)

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