JPH11293090A - Sealing resin composition and semiconductor sealed device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide sealing resin compositions excellent in storage stability under an ordinary temperature environment and capable of guaranteeing long- term reliability without affecting improved formulations of moisture resistance, reflow resistance, moldability or the like, and a semiconductor sealed devices. SOLUTION: A sealing resin compositions comprises (A) an epoxy resin; (B) a phenolic resin; (C) an inorganic filler; and (D) a curing promoter dispersed powder which is dispersed in a protective medium of a styrenic thermoplastic resin, the amount of the curing promoter contained being 15-30 wt.% relative to the dispersion and the average particle diameter of the dispersion being adjusted to 1-10 μm, as the essential components; and the amount of the inorganic filler (C) incorporated being 25-95 wt.%, based on the entire resin composition. Further, semiconductor sealed devices have chips sealed with a cured product of this composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to moldability, workability,
The present invention relates to a sealing resin composition having excellent long-term storage stability, reflow resistance and reliability, and a semiconductor sealing device.

[0002]

2. Description of the Related Art In recent years, in the field of semiconductor integrated circuits,
At the same time as the development of high integration and high reliability technologies, automation of the mounting process of semiconductor devices has been promoted. For example, when attaching a flat package type semiconductor device to a circuit board, soldering has conventionally been performed for each lead pin. Recently, however, the entire semiconductor device has been passed through an infrared (IR) reflow furnace heated to a maximum of 240 ° C. A method of performing solder pickling has been adopted. As a countermeasure for this, high filling of fillers has been promoted, and low-viscosity resins have been widely used.

[0003]

A semiconductor device encapsulated with a resin composition comprising a conventional epoxy resin such as a novolak type epoxy resin, a novolak type phenol resin, and an inorganic filler requires surface mounting of the entire device by IR reflow. There is a drawback that the moisture resistance is reduced when performing.
In particular, when the semiconductor device that has absorbed moisture is subjected to IR reflow, peeling between the sealing resin and the semiconductor chip, or between the sealing resin and the lead frame, and internal resin cracks occur, causing significant deterioration of moisture resistance and disconnection due to electrode corrosion. Leakage current due to moisture or moisture, and as a result, the semiconductor device has a drawback that long-term reliability cannot be guaranteed. For this reason, there has been a strong demand for the development of a material having a small influence on moisture resistance and good moldability with little moisture deterioration even when surface mounting is performed by IR reflow of the entire semiconductor device. Further, a resin having a low melt viscosity is used as a prescription for highly filling a filler. The use of a resin having such a low softening point has a disadvantage that the storage stability of an epoxy resin generally decreases.

The present invention has been made to solve the above-mentioned drawbacks, and has excellent storage stability at ordinary temperature, and has no influence on a prescription for improving moisture resistance, IR reflow resistance, moldability and the like. An object of the present invention is to provide a stopping resin composition and a semiconductor sealing device.

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above-mentioned object, and as a result, they have been protected with an epoxy resin, a phenol resin, an inorganic filler, and a styrene-based thermoplastic resin. By using a hardening agent-dispersed powder having an average particle size of 1 to 10 µm and a content of 15 to 30%, it has excellent long-term storage stability, moisture resistance, IR reflow resistance, moldability, workability, etc. It has been found that a resin composition having no influence on the prescription for improvement of the resin composition can be obtained, and the present invention has been completed.

That is, the present invention provides (A) an epoxy resin,
(B) a phenolic resin, (C) an inorganic filler and (D) a curing accelerator are dispersed in a styrene thermoplastic resin as a protective medium, and the curing accelerator is 15 to 30% by weight based on the dispersion.
And the dispersion has an average particle size of 1 to 10 μm.
The hardening accelerator dispersion powder adjusted as described above is an essential component, and the inorganic filler of (C) is added to the entire resin composition in an amount of 25 to
A sealing resin composition characterized in that it is contained in a proportion of 95% by weight. Further, there is provided a semiconductor sealing device wherein a semiconductor chip is sealed with a cured product of the sealing resin composition.

Hereinafter, the present invention will be described in detail.

The epoxy resin (A) used in the present invention is not particularly limited as long as it has two or more epoxy groups. Specifically, for example,

[0009]

Embedded image (Where n represents 0 or an integer of 1 or more)

[0010]

Embedded image

[0011]

Embedded image (Wherein, n represents 0 or an integer of 1 or more). Other common epoxy resins can be used alone or in combination.

The phenolic resin (B) used in the present invention is not particularly limited as long as it has two or more phenolic hydroxyl groups capable of reacting with the epoxy group of the epoxy resin (A). Specifically, for example,

[0013]

Embedded image (Where n represents 0 or an integer of 1 or more)

[0014]

Embedded image (Where n represents 0 or an integer of 1 or more)

[0015]

Embedded image (Where n represents 0 or an integer of 1 or more)

[0016]

Embedded image (Where n represents 0 or an integer of 1 or more)

[0017]

Embedded image (Wherein, n represents 0 or an integer of 1 or more), and these can be used as a mixture.

As the inorganic filler (C) used in the present invention, an inorganic filler having a low impurity concentration, a maximum particle diameter of 90 μm or less and an average particle diameter of 30 μm or less is preferably used. If the average particle size exceeds 30 μm, the moisture resistance and the moldability are poor, which is not preferable. Specific examples of the inorganic filler include, for example, silica powder, alumina powder, silicon nitride powder, antimony trioxide, talc, calcium carbonate, titanium white, clay, mica, red iron oxide, glass fiber, and the like. Two or more can be used in combination. Among these, silica powder and alumina powder are particularly preferable and are often used. It is preferable to mix the inorganic filler so that the inorganic filler is contained in an amount of 25 to 95% by weight based on the entire resin composition. If the proportion is less than 25% by weight, heat resistance, moisture resistance, solder heat resistance, mechanical properties and moldability will be poor, and if it exceeds 95% by weight, burrs will increase and the moldability will be poor, making it unsuitable for practical use.

The (D) curing accelerator dispersion powder used in the present invention is a dispersion in which a curing accelerator is incorporated in a styrene-based thermoplastic resin as a protective medium in a sea-island structure. Is a powder containing 15 to 30% by weight based on the dispersion and having the curing accelerator dispersed therein, the dispersion having an average particle diameter of 1 to 10 μm. The average particle size is preferably 1 to 10 μm, and particularly preferably 3 to 5 μm.
Is good. If the average particle size is 1 μm or less, the curing accelerator is not incorporated well, and the storage stability effect is poor, which is not preferable. On the other hand, if the average particle size exceeds 10 μm, the curing accelerator may not be released properly during molding, which may cause poor curing. The curing accelerator content is 15
It is preferably from 30 to 30% by weight, particularly preferably from 18 to 23% by weight. If it is less than 15% by weight, poor curing tends to occur, and if it exceeds 30% by weight, storage stability is poor, which is not preferable.

As the curing accelerator used here, phosphorus-based curing accelerators, imidazole-based curing accelerators, DBU-based curing accelerators, and other curing accelerators can be widely used and prepared. When a system hardening accelerator is used, its effect can be sufficiently exhibited.

The styrene-based thermoplastic resin used here includes, in addition to polystyrene, butadiene-modified polystyrene and pomethylstyrene, copolymer resins of styrene and metastyrene.

The epoxy resin composition of the present invention has an average particle size of 1 to 10 μm protected by the aforementioned epoxy resin, phenol resin, inorganic filler and styrene thermoplastic resin.
The hardening agent-dispersed powder having a content of 15 to 30% by weight as an essential component is an essential component. However, as long as the object of the present invention is not adversely affected, and if necessary, for example, natural waxes, synthetic waxes, Release agents such as metal salts of chain fatty acids, acid amides, esters, and paraffin; flame retardants such as chlorinated paraffin, brominated toluene, hexabromobenzene, and antimony trioxide; coloring agents such as carbon black and red iron oxide;
A rubber-based or silicone-based low stress imparting agent or the like can be appropriately added and blended.

A general method for preparing the encapsulating resin composition of the present invention as a molding material is as follows: the average particle size protected by the above-described epoxy resin, phenol resin, inorganic filler and styrene-based thermoplastic resin is as follows. A hardening accelerator dispersed powder having a content of 1 to 10 μm and a content of 15 to 30% by weight is blended, and after sufficiently uniformly mixed by a mixer or the like,
Further, a melt-mixing process using a hot roll or a mixing process using a kneader or the like is performed, and then the mixture is solidified by cooling and pulverized to an appropriate size to obtain a molding material. If the molding material obtained in this way is applied to sealing, covering, insulating, etc. of electronic parts or electric parts including semiconductor devices, it has a bad influence on reliability etc. while having excellent storage stability at room temperature. And a molded article can be obtained.

Further, the semiconductor sealing device of the present invention can be easily manufactured by sealing a semiconductor chip using the above-mentioned molding material. The semiconductor chip to be sealed is not particularly limited to, for example, an integrated circuit, a large-scale integrated circuit, a transistor, a thyristor, a diode, and the like. The most common sealing method is a low pressure transfer molding method, but sealing by injection molding, compression molding, casting, or the like is also possible. After sealing with a molding material, it is heated and cured, and finally a semiconductor sealing device sealed with this cured product is obtained. The curing by heating is desirably performed by heating to 150 ° C. or more.

[0025]

The epoxy resin composition for encapsulation and the semiconductor encapsulation device of the present invention have a mean particle size of 1 to 10 .mu.m protected by a styrene-based thermoplastic resin and a curing accelerator having a content of 15 to 30% by weight. By using the dispersed powder, the storage stability of the resin composition could be significantly improved. In addition, there is no influence on the moldability of the resin composition by the epoxy resin and the phenol resin and other additives, and the prescription for improving the bonding strength to the frame.

[0026]

Next, the present invention will be described with reference to examples, but the present invention is not limited to these examples. "%" In the following Examples and Comparative Examples
Means "% by weight".

Example 1 5.0% of the epoxy resin of the above formula (epoxy equivalent: 195),
Phenol resin of the above formula (phenol equivalent 170) 4.0
%, Fused silica powder 89%, a hardening accelerator 1.0% containing 20% triphenylphosphine having an average particle size of 5 μm and protected by the styrene-based thermoplastic resin, and 1.0% ester waxes were mixed at room temperature. After further kneading and cooling at 90 to 95 ° C, the mixture was pulverized to produce a molding material (A).

Example 2 5.0% of the epoxy resin of the above formula (epoxy equivalent: 195),
Phenol resin of the above formula (phenol equivalent 170) 4.0
%, A fused silica powder 89%, a curing accelerator 1.0% having an average particle diameter of 10 μm protected by the styrene-based thermoplastic resin and containing 20% of triphenylphosphine, and 1.0% of an ester-based wax mixed at room temperature. Further, after kneading and cooling at 90 to 95 ° C., the mixture was pulverized to produce a molding material (B).

Comparative Example 1 5.0% of the epoxy resin of the above formula (epoxy equivalent: 195),
Phenol resin of the above formula (phenol equivalent 170) 4.0
%, A fused silica powder 89%, a curing accelerator 1.0% having an average particle diameter of 20 μm protected by the styrene-based thermoplastic resin and containing 14% of triphenylphosphine, and 1.0% of an ester-based wax mixed at room temperature. Further, after kneading and cooling at 90 to 95 ° C., the mixture was pulverized to produce a molding material (C).

Comparative Example 2 5.17% of the epoxy resin of the above formula (epoxy equivalent: 195),
Phenol resin of the above formula (phenol equivalent 170) 4.17
%, Fused silica powder 89.5%, triphenylphosphine 0.
16% and 1.0% of ester waxes were mixed at room temperature, kneaded and cooled at 90 to 95 ° C, and then pulverized to produce a molding material (D).

The molding materials (A) to (D) thus produced
After transfer molding at 175 ° C for 2 minutes using, the specimen was prepared by after-curing at 175 ° C for 8 hours. For these molding materials and test pieces, moldability,
Gel time, melt viscosity by Koka type flow tester, water absorption (PCT), glass transition temperature, frame material 4
The adhesive strength to alloy 2 and silver plating, spiral flow, storage stability of spiral flow over time, and reflow resistance were measured. Table 1 and Table 2 show the above measurement results.
As described above, the remarkable effect of the present invention could be confirmed.

[0032]

[Table 1] * 1: The measurement temperature is 180 ° C. * 2: The measurement temperature is 180 ° C. * 3: The molding material was transfer-molded at 175 ° C for 2 minutes, and after-cured at 175 ° C for 8 hours to produce a molded product. This was left for 24 hours in saturated steam at 127 ° C. and 2 atm, and the weight was determined. * 4: A sample with dimensions of 2.5 × 2.5 × 15.0 to 20.0 was prepared from the same molded product as in the test for water absorption, and a thermomechanical analyzer DL-1500H (trade name, manufactured by Vacuum Riko Co., Ltd.) was used. The measurement was performed at a heating rate of 5 ° C./min.

[0033]

[Table 2] * 5: The spiral measurement temperature is 175 ° C, and the material is initially left in an environment of 25 ° C. * 6: A 14.5 mm x 14.5 mm x 1.4 mm VQFP was molded using a 6.2 mm x 6.2 mm evaluation element under the conditions of 175 ° C for 90 seconds, and after-curing was performed at 175 ° C for 8 hours. Next, the package was left in an atmosphere of 85 ° C. and a relative humidity of 60% and 85% for 168 hours to perform a moisture absorption treatment, and then passed through an IR reflow furnace having a maximum temperature of 240 ° C. three times. At this point, the occurrence of cracks in the package and the occurrence of peeling from the lead frame were examined.

[0034]

As is clear from the above description and Tables 1 and 2, the encapsulating resin composition of the present invention has excellent storage stability at room temperature and has no influence on other characteristic values. Therefore, a semiconductor sealing device having high reliability can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 23/31

Claims (2)

[Claims] 1. An epoxy resin, (B) a phenolic resin, (C) an inorganic filler and (D) a curing accelerator are dispersed in a styrene thermoplastic resin as a protective medium, and the curing accelerator is a dispersion. And a hardening accelerator-dispersed powder whose dispersion has been adjusted to an average particle size of 1 to 10 μm as an essential component, and which is contained in the above (C) based on the entire resin composition. A sealing resin composition comprising an inorganic filler in a ratio of 25 to 95% by weight. 2. An epoxy resin, (B) a phenolic resin, (C) an inorganic filler and (D) a curing accelerator are dispersed in a styrene thermoplastic resin as a protective medium, and the curing accelerator is a dispersion. And a hardening accelerator-dispersed powder whose dispersion has been adjusted to an average particle size of 1 to 10 μm as an essential component, and which is contained in the above (C) based on the entire resin composition. A semiconductor sealing device wherein a semiconductor chip is sealed with a cured product of a sealing resin composition containing an inorganic filler at a ratio of 25 to 95% by weight.