JP3451666B2 - Epoxy 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 an epoxy resin composition for semiconductor encapsulation, which has low water absorption, excellent solder heat resistance, low curing shrinkage, and less warpage of a package immediately after molding.

[0002]

2. Description of the Related Art Epoxy resins are excellent in heat resistance, moisture resistance, electrical characteristics, adhesiveness, etc., and can be given various characteristics by blending formulation, so they are used as industrial materials such as paints, adhesives and electrical insulation materials. Has been done.

For example, as a method of sealing electronic circuit parts such as semiconductor devices, hermetic seals made of metal or ceramics and phenol resin, silicone resin, etc. have hitherto been used.
Resin encapsulation with an epoxy resin or the like has been proposed. However, resin sealing with an epoxy resin is mainly used from the viewpoint of the balance of economy, productivity and physical properties.

In recent years, densification and automation have also been promoted in mounting components on a printed circuit board. Instead of the conventional "insertion mounting method" in which lead pins are inserted into holes in the substrate, components are soldered to the surface of the substrate. "Surface mounting method" has become popular. Along with this, the package is also shifting from the conventional DIP (dual in-line package) to a thin FPP (flat plastic package) suitable for high-density mounting and surface mounting.

With the shift to the surface mounting system, the soldering process, which has not been a problem so far, has become a big problem. In the conventional pin insertion mounting method, the lead portion is only partially heated in the soldering process, but in the surface mounting method, the entire package is immersed in a heating medium and heated. As the soldering method in the surface mounting method, immersion in a solder bath, heating with saturated vapor of inert gas (vapor phase method)
Although an infrared reflow method or the like is used, the whole package is heated to a high temperature of 210 to 270 ° C. by either method. Therefore, the package sealed with the conventional sealing resin has a problem that the resin part is cracked during soldering or peeling occurs between the chip and the resin, which reduces reliability and cannot be used as a product. Occurs.

The occurrence of cracks in the soldering process is
It is said that the moisture absorbed between the post-curing and the mounting process explosively vaporizes and expands during soldering heating.As a countermeasure against this, the post-cured package is completely dried and sealed. The method of storing and shipping is used.

Various improvements have been made to the sealing resin. For example, a method of blending a phenol aralkyl resin as a curing agent (JP-A-53-299 and JP-A-59-6).
7660, JP-A-3-207714, JP-A-4-48759, JP-A-4-55423) and the like are proposed.

Further, due to the recent thinning of the package,
Warpage of the package immediately after molding due to curing shrinkage of the sealing resin has become a problem. When the package warps, cracks occur in the package in the tie bar cutter process, and pin tips do not contact the substrate in the reflow soldering process, resulting in insufficient soldering.

[0009]

However, the method of enclosing the dry package in the container has a drawback that the manufacturing process and the handling work of the product are complicated and the product price is high.

Further, resins improved by various methods have been gradually effective, but they are still not sufficient. A method of blending a phenol aralkyl resin as a curing agent (JP-A-53-299 and JP-A-59-67).
660, JP-A-3-207714, JP-A-4-48759, and JP-A-4-55423).
Although it has an effect of preventing cracks in the resin portion during soldering, it is not practical in consideration of productivity of the thin package because of large warpage immediately after molding the thin package.

It is an object of the present invention to provide an epoxy resin composition for semiconductor encapsulation which solves the problem of cracks generated in the soldering process and has little warpage of the package immediately after molding and excellent productivity.

The present inventors have found that by adding a specific epoxy resin and a curing agent having a specific structure, the above objects can be achieved and an epoxy resin composition that meets the purpose can be obtained. Reached

That is, the present invention relates to an epoxy resin (A),
An epoxy resin composition containing a curing agent (B) and a filler (C), wherein the epoxy resin (A) contains an epoxy resin (a) represented by the following formula (I) as an essential component.
Contains, and contains the curing agent (B) is (hereinafter referred to as copolymer (b)) naphthol / phenol paraxylene copolymer (b) as essential components, a copolymer
Epoxy resin composition for semiconductor encapsulation , wherein the constituent molar ratio of (b) is 2/8 to 5/5, and the proportion of the filler (C) is 84 to 89 % by weight of the entire composition. It is a thing.

[Chemical 2] (However, R ¹ to R ⁸ represent a hydrogen atom, a C1-C4 lower alkyl group or a halogen atom.)

The structure of the present invention will be described in detail below.

In the epoxy resin (A) of the present invention
The component other than the epoxy resin (a) is not particularly limited as long as it has two or more epoxy groups in one molecule, and specific examples thereof include, for example, cresol novolac type epoxy resin and phenol novolac type epoxy resin.
Examples include fats, bisphenol A type epoxy resins , bisphenol F type epoxy resins, linear aliphatic type epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, spirocyclic epoxy resins and brominated epoxy resins.

The epoxy resin (A) in the present invention has the following formula (I):

[Chemical 3] (However, R ¹ to R ⁸ are hydrogen atoms, C ¹ -C ⁴ lower alkyl
A kill group or a halogen atom is shown. ) Epoki represented by
It is necessary to contain resin (a) in terms of solder heat resistance
Is . More preferably, the content of the epoxy resin in the epoxy resin (A) is 50% by weight or more, and particularly preferably 70% by weight or more.

Preferred specific examples of the epoxy resin (a) are 4,4'-bis (2,3-epoxypropoxy) biphenyl and 4,4'-bis (2,3-epoxypropoxy) -3,3 '. , 5,5'-tetramethylbiphenyl,
4,4'-bis (2,3-epoxypropoxy) -3,
3 ', 5,5'-tetramethyl-2-chlorobiphenyl, 4,4'-bis (2,3-epoxypropoxy)-
3,3 ', 5,5'-Tetramethyl-2-bromobiphenyl, 4,4'-bis (2,3-epoxypropoxy)
-3,3 ', 5,5'-tetraethylbiphenyl, 4,
4'-bis (2,3-epoxypropoxy) -3,3
′, 5,5′-Tetrabutylbiphenyl, 4,4′-bis (2,3-epoxypropoxy) biphenyl, 4,4
′ -Bis (2,3-epoxypropoxy) -3,3 ′,
Examples include 5,5'-tetramethylbiphenyl.

In the present invention, the compounding amount of the epoxy resin (A) is usually 3 to 15% by weight, preferably 3 to 10% by weight. If the compounding amount of the epoxy resin (A) is less than 3% by weight, the moldability and adhesiveness are insufficient, and if it exceeds 15% by weight, the linear expansion coefficient becomes large and it becomes difficult to reduce the stress, which is not preferable.

The curing agent (B) in the present invention is a copolymer
It is important to contain (b) as an essential component. If the copolymer (b) is not contained, it is not possible to obtain a resin having excellent solder heat resistance and warpage of the package immediately after molding.

In the copolymer (b), that is, the naphthol / phenol paraxylene copolymer (b), the molar ratio of naphthol to phenol is 2/8 to 5/5.
Composed of.

Further, the curing agent (B) in the present invention may be used in combination with a curing agent other than the copolymer (b). Examples of the curing agent that can be used in combination include phenol novolac resin, cresol novolac resin, and the following general formula (II)

[Chemical 4] (In the formula, R may be the same or different and each represents a hydrogen atom, a halogen atom or an alkyl group having 1 to 4 carbon atoms. N represents an integer of 0 or more.) Phenol having a skeleton Compound, maleic anhydride, phthalic anhydride,
Examples thereof include acid anhydrides such as pyromellitic dianhydride and aromatic amines such as metaphenylenediamine, diaminodiphenylmethane and diaminodiphenylsulfone.

The addition amount of the copolymer (b) in the present invention is not particularly limited, and the effect of the present invention is exhibited if the copolymer (b) is contained as an essential component, but in order to exert a more sufficient effect, The copolymer (b) must be contained in the curing agent (B) in an amount of usually 20% by weight or more, preferably 50% by weight or more, more preferably 70% by weight or more.

In the present invention, the content of the curing agent (B) is usually 2 to 15% by weight, preferably 2 to 10% by weight, more preferably 2 to 8% by weight. Further, the blending ratio of the epoxy resin (A) and the curing agent (B) is such that the chemical equivalent ratio of (B) to (A) is 0 in terms of mechanical properties and moisture resistance reliability.
It is preferably in the range of 5 to 1.5, particularly 0.8 to 1.2.

In the present invention, a curing catalyst may be used to accelerate the curing reaction between the epoxy resin (A) and the curing agent (B). The curing catalyst is not particularly limited as long as it accelerates the curing reaction, and for example, 2-methylimidazole, 2,4
-Dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-
Imidazole compounds such as 4-methylimidazole and 2-heptadecylimidazole, triethylamine, benzyldimethylamine, α-methylbenzyldimethylamine, 2- (dimethylaminomethyl) phenol, 2,
4,6-tris (dimethylaminomethyl) phenol,
1,8-diazabicyclo (5,4,0) undecene-7
Such as tertiary amine compounds, zirconium tetramethoxide, zirconium tetrapropoxide, tetrakis (acetylacetonato) zirconium, tri (acetylacetonato) aluminum and other organometallic compounds, and triphenylphosphine, trimethylphosphine, triethylphosphine, tributylphosphine And organic phosphine compounds such as tri (p-methylphenyl) phosphine and tri (nonylphenyl) phosphine. Among them, organic phosphine compounds are preferable, and triphenylphosphine is particularly preferably used, from the viewpoint of moisture resistance. Two or more kinds of these curing catalysts may be used in combination depending on the use, and the addition amount thereof is preferably in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the epoxy resin (A).

As the filler (C) in the present invention, fused silica, crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia, clay, talc, calcium silicate, titanium oxide, antimony oxide, asbestos, glass fiber, etc. Among them, fused silica is preferably used because it has a large effect of lowering the linear expansion coefficient and is effective in reducing stress.

The fused silica referred to herein means an amorphous silica having a true specific gravity of 2.3 or less. The production does not necessarily have to go through the molten state, and any production method can be used. For example, a method of melting crystalline silica, a method of synthesizing from various raw materials, and the like can be mentioned.

The shape and particle size of the fused silica are not particularly limited, but it is preferable to contain spherical fused silica in the filler in an amount of 84 to 89 % by weight from the viewpoint of fluidity and solder heat resistance.

In the present invention, the proportion of the filler (C) is 80 to 95% by weight based on the total weight in view of moldability and low stress.

In the present invention, the surface treatment of the filler (C) with a coupling agent such as a silane coupling agent or a titanate coupling agent is preferable in terms of reliability. As the coupling agent, silane coupling agents such as epoxysilane, aminosilane, mercaptosilane and the like are preferably used.

The epoxy resin composition of the present invention includes halides such as halogenated epoxy resins, flame retardants such as phosphorus compounds, flame retardants such as antimony trioxide, colorants such as carbon black and iron oxide, and silicone rubber. , Olefin copolymers, modified nitrile rubber, modified polybutadiene rubber, modified silicone oil and other elastomers, polyethylene and other thermoplastic resins, long chain fatty acids, long chain fatty acid metal salts, long chain fatty acid esters, long chain fatty acid A release agent such as amide or paraffin wax, an ion scavenger such as hydrotalcites, or a cross-linking agent such as organic peroxide can be optionally added.

The epoxy resin composition of the present invention is preferably melt-kneaded, for example by melt-kneading using a known kneading method such as a Banbury mixer, a kneader, a roll, a single or twin screw extruder and a cokneader. , Manufactured.

[0032]

EXAMPLES The present invention will be specifically described below with reference to examples. In addition,% in an Example shows weight%.

Examples 1 to 3 and Comparative Examples 1 and 2 The components shown in Table 1 were dry blended with a mixer in the composition ratios shown in Table 5. Roll surface temperature 90
The mixture was heated and kneaded for 5 minutes using a mixing roll at ℃, cooled and pulverized to produce an epoxy resin composition for semiconductor encapsulation. This composition was molded by a low-pressure transfer molding method under the conditions of 175 ° C. × 2 minutes, post-cured under the condition of 180 ° C. × 5 hours, and the physical properties of each composition were measured by the following physical property measuring methods.

Solder heat resistance: 160 pin with a chip size of 12 × 12 mm and mounting a simulated element with Al vapor deposition on the surface
TQFP 20 pieces are molded and post-cured, 85 ℃ / 8
After humidifying at 5% RH for 72 hours, heat treatment was performed in an IR reflow furnace having a maximum temperature of 240 ° C., and the number of external cracks was examined.

Moisture resistance reliability: Using QFP after solder heat resistance evaluation, under PCT conditions of 121 ° C./100% RH, the time at which the cumulative failure rate becomes 50% by breaking the Al wiring is determined as the life.

Curing shrinkage ratio: A disc of 4 inches was molded,
The diameter immediately after molding was measured with a micrometer to determine the molding shrinkage.

[0037]

[Table 1]

[0038]

[Table 2]

As can be seen from Table 2, the epoxy resin compositions of the present invention (Examples 1 to 3) have solder heat resistance, water absorption,
Excellent cure shrinkage. Among them, Examples 2 and 3 using a curing agent having a high naphthol content are excellent in solder heat resistance, water absorption, and curing shrinkage. On the other hand, curing agent (B)
Comparative Examples 1 and 2 which do not contain the copolymer (b) therein are inferior in solder heat resistance, water absorption and curing shrinkage.

[0040]

EFFECT OF THE INVENTION The epoxy resin composition for semiconductor encapsulation of the present invention has good solder heat resistance and water absorption, and has good curing shrinkage because it contains a specific epoxy resin and a specific copolymer as a curing agent. It has low productivity and excellent productivity.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 23/29 C08G 59/62 H01L 23/31

Claims (2)

(57) [Claims] 1. An epoxy resin composition comprising an epoxy resin (A), a curing agent (B) and a filler (C),
The epoxy resin (A) contains an epoxy resin (a) represented by the following formula (I) as an essential component, and the curing agent (B) contains a naphthol / phenolparaxylene copolymer (b) as an essential component. And naphthol / fe
The molar ratio of the norparaxylene copolymer (b) is 2
/ 8 to 5/5, and the proportion of the filler (C) is the composition.
An epoxy resin composition for semiconductor encapsulation, which is 84 to 89 % by weight of the whole . [Chemical 1] (However, R ¹ to R ⁸ represent a hydrogen atom, a C1-C4 lower alkyl group or a halogen atom.) 2. A epoxy resin for semiconductor encapsulation according to claim 1
A semiconductor device, which is encapsulated with an oil composition.