JPH06112366A - Resin composition for sealing semiconductor - Google Patents

Abstract

PURPOSE:To improve solder crack resistance, moisture resistance, and heat resistance by containing epoxy resin, a hardener and an inorganic filler, which contain specified amounts of specified denatured phenol resin compositions, as resin composition for sealing semiconductors, for its mandatory ingredients. CONSTITUTION:This is a resin composition consisting of epoxy resin, which contains 5-100wt.% biphenyl epoxy resin expressed by formula II (R1, F2, R3, and R4 are H or CH3) to a total quantity of epoxy resin, a hardener, which contains 50-100wt.% denatured biphenyl resin compositions expressed by formula I (R1, R2, and R3 are any of H, CH3, and OH) (l=1-10, m=1-10, n=1-10) to a total quantity of hardener, and an inorganic filler, which contains them by 75-90wt.% to all compositions. The inorganic fillers can be mixed in large quantity without losing the fluidity, since the melt viscosity of the fused epoxy resin itself is low, by using the biphenyl epoxy expressed by the formula II, so strong resin compositions little in moisture adsorption and excellent in solder stress property can be gotten.

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 the use of a phenol aralkyl resin improves the adhesion to a lead frame and low water absorption, and reduces the occurrence of cracks. However, in the phenol aralkyl curing agent system, the glass transition temperature of the cured product is However, it has a drawback that it is significantly lower than the conventional phenol novolac curing agent system and its 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 modified 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, and

[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 75 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 modified phenol resin curing agent having the structure represented by the formula (1) is a compound having an aromatic ring in the side chain of the molecule. The properties differ slightly depending on the structure of R _{1 to} R ₃ in the side chain, but the characteristic is that, unlike conventional phenol novolac curing agents, it has low hygroscopicity and excellent flexibility when heated. If such a flexible structure is incorporated into the molecule, the glass transition temperature will be lowered, but unlike a linear phenol aralkyl resin, it has a large molecule in the side chain, and therefore, a standard R _{Even when 1 to} R ₃ are H, it shows a relatively high glass transition temperature. Further, by introducing a reactive OH group into R _{1 to} R ₃ , the crosslink density of the cured product can be adjusted, and therefore the glass transition temperature can be further improved. Further, when R ₁ is a CH ₃ group, it has a lower hygroscopic property. The structures of R _{1 to} R ₃ in these side chains may be the same or different and can be appropriately selected according to the desired characteristics. When any one of l, m, and n in the formula (1) exceeds 10, the fluidity at the time of molding deteriorates. By adjusting the amount of the modified phenol resin curing agent used, solder crack resistance can be maximized. In order to obtain the effect of solder crack resistance, it is desirable to use the modified phenol resin curing agent represented by the formula (1) 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. If it is less than 50% by weight, low moisture absorption and flexibility at the time of 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,
A cresol novolac resin, a dicyclopentadiene modified phenolic resin, a co-condensate of a dicyclopentadiene modified phenolic resin with a phenol novolac or a cresol novolac resin, a phenol aralkyl resin and the like can be used. Phenolic resins used in combination with these
Although appropriately used for the purpose of adjusting curability and imparting flexibility, low molecular compounds such as bisphenol F and narrow low molecular weight phenol novolac resin are suitable for adjusting fluidity.

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 compounding amount of the inorganic filler is preferably in the range of 75 to 90% by weight. 75% 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 4 and Comparative Examples 1 to 3 (A) Epoxy resin Orthocresol novolac type epoxy resin (epoxy equivalent 200, softening point 65 ° C) Biphenyl type epoxy resin: 3,3 ', 5,5'-
Tetramethyl-4,4′-dihydroxybiphenylglycidyl ether (B) Phenolic resin curing agent Modified phenol resin represented by the formula (1) (hydroxyl group equivalent 212, softening point 80 ° C., R ₁ , R ₂ and R ₃ are H). Phenol novolac resin (hydroxyl group equivalent 104, softening point 95 ° C) Phenol aralkyl resin (hydroxyl group equivalent 180, softening point 80 ° C) (C) Inorganic filler fused silica powder (average particle size 14 µm) (D) Other raw materials Curing accelerator: Triphenylphosphine release agent: Carnauba wax was mixed in the respective proportions shown in Table 1 at room temperature with a mixer, kneaded with a twin-screw roll at 70 to 100 ° C, cooled and pulverized to obtain a molding material, which was tableted. Thus, an epoxy resin composition for semiconductor encapsulation was obtained. 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 Heat resistance A glass transition temperature of the cured product was determined by measuring the thermal expansion characteristics of a test piece that was molded under the conditions of 175 ° C. for 2 minutes and post-cured at 175 ° C. for 8 hours. * 3 Solder crack resistance test 1: Molded product (chip size 36 mm ² , package thickness 2.
(05 mm) 10 pieces are treated at 85 ° C and steam of 85% RH for 72 hours, and then treated with a VPS soldering machine at 215 ° C, 9 hours.
It was held for 0 seconds and observed for external cracks. 2: Molded product (chip size 36 mm ² , package thickness 2.
(05 mm) After 10 pieces of 72 hours under 85 ° C. and 85% RH water vapor, the infrared reflow soldering equipment will be used for 24 hours.
It was held at 0 ° C. for 10 seconds and observed for external cracks. * 4 Solder moisture resistance test A 16pSOP package equipped with a simulated element is molded and cured, treated for 72 hours in an environment of 85 ° C and 85% RH, then immersed in a solder bath at 260 ° C for 10 seconds, and then subjected to a pressure cooker test (125 ° C, 100% RH)
The number of open defects in the circuit was measured.

[0016]

[Table 1]

[0017]

Industrial Applicability The resin composition for semiconductor encapsulation according to the present invention is remarkably excellent in solder cracking property, moisture resistance and heat resistance, and thus has an extremely high industrial value as a surface mounting encapsulation resin composition.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical indication C08K 3/00 C08L 63/00 NKT 8830-4J

Claims (2)

[Claims] 1. A curing agent containing (A) an epoxy resin, (B) a curing agent, and a modified 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. [Chemical 1] A resin composition for semiconductor encapsulation, wherein (C) the inorganic filler is an essential component, and (C) the inorganic filler is 75 to 90% by weight in the whole composition. 2. The semiconductor encapsulation according to claim 1, wherein the epoxy resin (A) is a biphenyl epoxy resin represented by the formula (2), and is 50 to 100% by weight based on the total amount of the epoxy resin. Stopping resin composition. [Chemical 2] (R ₁ , R ₂ , R ₃ and R ₄ are H or CH ₃ )