JPH10306201A - Epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition, excellent in flame retardance, moldability, solder heat resistance and high-temperature reliability and useful for sealing semiconductors by including an epoxy resin, a curing agent, an amorphous silica and other inorganic fillers and a phosphoric ester compound therein. SOLUTION: This composition comprises (A) an epoxy resin containing a biphenyl type epoxy resin having preferably a skeleton represented by formula I (R1 to R8 are each H or a 1-4C alkyl), (B) a curing agent which is a compound preferably represented by the formula Y-CH2 -X-CH2 -(Y-CH2 -X-CH2 )m -Y [(m) is >=0; X is a mono- or a bivalent aromatic group; Y is a mono- or a bivalent aromatic group having a phenol group] or a phenolaralkyl resin, (C) a filler containing an amorphous silica and other inorganic fillers such as a crystalline silica or alumina and (D) a phosphoric ester compound containing a skeleton preferably represented by formula II (X is a mono- or a polyvalent aromatic group). The composition has >=1.2 W/m.K heat conductivity after curing.

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 having excellent flame retardancy, reliability and soldering heat resistance, and more particularly to an epoxy resin composition for semiconductor encapsulation and a semiconductor device.

[0002]

2. Description of the Related Art As a method of sealing an electronic circuit portion such as a semiconductor device, a sealing resin comprising an epoxy resin, a curing agent, and an inorganic filler is used in view of the balance between economy, productivity, and physical properties. Resin sealing has become common. As semiconductor devices become thinner and higher in density in recent years, required properties such as moldability and solder heat resistance for sealing resins are also increasing.

Further, these electronic components such as semiconductors include:
In order to ensure safety, provision of flame retardancy is required by UL standards. Therefore, conventional sealing resins have been added with a halide-based flame retardant such as a brominated epoxy resin as a flame retardant and an antimony compound such as antimony trioxide as a flame retardant aid.

However, these flame retardants and flame retardant auxiliaries not only cause a decrease in the reliability of the semiconductor, but also generate halogen gas at the time of burning, and contain a flame retardant and a flame retardant auxiliaries. There is a problem of waste disposal of resin.

[0005]

In order to solve the above problems, the inventors have already proposed in Japanese Patent Application No. 7-343947 to add a phosphorus-based flame retardant.

However, in order to ensure flame retardancy with a phosphorus-based flame retardant (phosphate ester compound) without using a conventional flame retardant or flame retardant auxiliary agent, a phosphorus-based flame retardant (P It is necessary to incorporate a large amount of a phosphoric ester compound), and further improvements are required in moldability, solder heat resistance, PCBT characteristic life (humidity reliability under voltage application), and the like.

[0007] The present invention relates to flame retardancy, moldability, solder heat resistance,
It is an object of the present invention to provide an epoxy resin composition for semiconductor encapsulation which is excellent in high-temperature reliability and does not contain a halide-based flame retardant which is a conventional flame retardant and antimony oxide.

[0008]

That is, the present invention provides: The epoxy resin (A), the curing agent (B), the filler (C), and the phosphate compound (D) are contained as essential components, and the filler (C) is made of amorphous silica and other inorganic fillers. And an epoxy resin composition having a thermal conductivity after curing of 1.2 W / mK or more. ""The content of the filler (C) is from 75 to 75% of the resin composition.
The epoxy resin composition according to claim 1, wherein the amount is 97% by weight. "3. The epoxy resin composition according to claim 1 or 2, wherein the phosphate compound (D) has a skeleton represented by the following chemical formula (I).

Embedded image (In the formula, X may be the same or different and represents a monovalent or higher valent aromatic group.) " The content of a phosphorus atom derived from the phosphate compound (D) is 0.1 to 5% by weight based on a resin component excluding a filler in the epoxy resin composition.
3. The epoxy resin composition according to any one of 3. "5. 5. The epoxy resin composition according to any one of the above, wherein the filler (C) contains one or more kinds of high thermal conductive particles selected from crystalline silica, alumina, silicon nitride, and aluminum nitride as essential components. Any of the above epoxy resin compositions wherein the epoxy resin (A) essentially comprises a biphenyl type epoxy component having the structure of the following formula (II).

Embedded image (However, R1 to R8 in the formula are a hydrogen atom, a carbon number 1 to 4
Represents an alkyl group or a halogen atom). " Any of the above epoxy resin compositions wherein the curing agent (B) comprises a phenol aralkyl resin having the structure of the following chemical formula (III) as an essential component.

Embedded image (In the formula VI, m is an integer of 0 or more, X is a monovalent or divalent aromatic group which may be the same or different, Y is a monovalent or divalent group having a phenol group which may be the same or different.)
Valent aromatic group. 7.) 8. The epoxy resin composition according to any one of the above, wherein the content of the filler (C) is 85 to 95% by weight. 9. Any one of the above epoxy resin compositions for semiconductor encapsulation. It is intended to provide a "semiconductor device in which a semiconductor element is sealed with the epoxy resin composition."

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail.
In the present invention, “weight” means “mass”.

In the epoxy resin composition of the present invention, the thermal conductivity of the cured product is important. Thermal conductivity is a measure of the amount of heat transported purely by conduction only and is represented by the proportionality constant k in Fourier's law equation.

## EQU1 ## q = -k (dT / dz) q: heat quantity passing through a unit cross-sectional area during a unit time dT / dz: temperature gradient

[0011] The thermal conductivity will be explained from the measurement principle.

K = αρC _p (where α is the thermal diffusivity, ρ is the density, and C _p is the specific heat).

The resin composition of the present invention comprises 25
It is necessary that the thermal conductivity measured at around ° C. is 1.2 W / m · K or more. If the thermal conductivity is low, sufficient flame retardancy cannot be obtained. The cured product of the epoxy resin composition as used herein means the epoxy resin composition of the present invention at a temperature of, for example, 120 to 250 ° C., preferably 150 to 200 ° C., such as transfer molding, injection molding, and casting. And if necessary, an additional heat treatment (for example, 150 to 180 ° C., 2 to 16 hours) is performed so that the chemical reaction between the epoxy resin and the curing agent or the physical properties of the composition become saturated. is there.

The epoxy resin (A) in the present invention is not particularly limited as long as it has a plurality of epoxy groups in a molecule, and specific examples thereof include, for example, a cresol novolak type epoxy resin, a phenol novolak type epoxy resin, and biphenyl. Epoxy resin, bisphenol A
Epoxy resin, bisphenol F epoxy resin, various novolak epoxy resins synthesized from bisphenol A and resorcin, linear aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, spiro ring-containing epoxy resin and Halogenated epoxy resins are exemplified. In the epoxy resin (A), two or more epoxy resins can be used in combination.

Among these epoxy resins (A), those which are particularly preferably used in the present invention are essentially biphenyl type epoxy resins having a skeleton represented by the following chemical formula (II) because of their excellent solder heat resistance. It is contained as a component.

Embedded image (However, R1 to R8 in the formula are a hydrogen atom, a carbon number 1 to 4
Further, the epoxy resin (A) preferably contains at least 50% by weight, especially at least 70% by weight of a biphenyl type epoxy resin having a biphenyl skeleton having a skeleton represented by the above formula (II).

Preferred specific examples of the epoxy resin skeleton represented by the above formula (I) include 4,4'-bis (2,3-epoxypropoxy) biphenyl 4,4'-bis (2,3-epoxypropoxy). ) -3,3 ', 5,5'-Tetramethylbiphenyl 4,4'-bis (2,3-epoxypropoxy) -3,3', 5,5'-Tetraethylbiphenyl 4,4'-bis (2 , 3-epoxypropoxy) -3,3 ', 5,5'-tetrabutylbiphenyl and the like, and they are sufficiently effective when used alone or in a mixed system.

In the present invention, the amount of the epoxy resin (A) is usually 0.05 to 20% by weight, more preferably 2 to 10% by weight in the epoxy resin composition from the viewpoint of moldability and adhesion. is there. If the amount of the epoxy resin (A) is too small, the moldability and adhesion become insufficient,
When the amount is too large, the coefficient of linear expansion of the cured product increases, and it tends to be difficult to reduce the stress of the cured product.

The curing agent (B) in the present invention is not particularly limited as long as it reacts with the epoxy resin (A) and cures. Usually a compound having a phenolic hydroxyl group,
Compounds having acid anhydrides and amines are used. Among these, specific examples of the phenolic curing agent, that is, the compound having two or more phenolic hydroxyl groups in the molecule are, for example, synthesized from phenol novolak resin, cresol novolak resin, phenol aralkyl resin, bisphenol A, resorcin, and the like. Examples include various novolak resins, various polyhydric phenol compounds such as tris (hydroxyphenyl) methane and dihydrobiphenyl, and polyvinyl phenol.

Examples of the compound having an acid anhydride include maleic anhydride, phthalic anhydride, and pyromellitic anhydride.

Examples of the amines include aromatic amines such as metaphenylenediamine, di (aminophenyl) methane (commonly called diaminodiphenylmethane) and diaminodiphenylsulfone. For semiconductor encapsulation, a phenol-based curing agent is preferably used from the viewpoint of heat resistance, moisture resistance and storage stability, and two or more curing agents may be used in combination depending on the application.

Among these curing agents (B), those which are particularly preferably used in the present invention are the compounds represented by the above formula (VI) and the compounds represented by the following formula (III) in view of low water absorption and excellent solder heat resistance. The phenol aralkyl resin represented by ()) is exemplified. Further, the phenol aralkyl resin is preferably contained in the curing agent (B) in an amount of 50% by weight or more.

Embedded image (Where m is an integer of 0 or more, and R represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.) In the present invention, the compounding amount of the curing agent (B) is usually 0.5
-20% by weight, preferably 1-10% by weight. Further, the mixing ratio of the epoxy resin (A) and the curing agent (B) is such that the chemical equivalent ratio of (B) to (A) is 0.5 to 1.5, particularly 0, from the viewpoint of mechanical properties and moisture resistance reliability. .8-
It is preferably in the range of 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 promotes the curing reaction. For example, 2-methylimidazole,
Imidazole compounds such as 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-heptadecylimidazole, triethylamine, benzyldimethylamine, α-methylbenzyl Tertiary amine compounds such as dimethylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, 1,8-diazabicyclo (5,4,0) undecene-7, zirconium tetra Organometallic compounds such as methoxide, zirconium tetrapropoxide, tetrakis (acetylaceto) zirconium, tri (acetylaceto) aluminum and triphenylphosphine, trimethylphosphine, triethylphosphine, trib Le phosphine, tri (p- methylphenyl) phosphine, an organic phosphine compound such as tri (nonylphenyl) phosphine and the like. Among them, an organic phosphine compound is preferably used from the viewpoint of moisture resistance. Two or more of these curing catalysts may be used in combination depending on the application, and the addition amount thereof is preferably in the range of 0.1 to 10 parts by weight based on 100 parts by weight of the epoxy resin (A).

The filler (C) in the present invention contains amorphous silica and other inorganic fillers as essential components. Other inorganic fillers include crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia, clay, talc, calcium silicate, titanium oxide, antimony oxide, asbestos, glass fiber and the like. Amorphous silica is an essential component because it has a great effect of lowering the coefficient of linear expansion and is effective in reducing stress.

The amorphous silica of the present invention, unlike crystalline silica, is an amorphous silica in which the constituent elements of silica, silicon and oxygen, are not regularly arranged and are not in a crystalline state. . Amorphous silica can be obtained, for example, by melting crystalline silica and then rapidly cooling it (fused silica).

The amorphous silica can be produced by any production method. For example, a method of melting crystalline silica,
Examples include a method of synthesizing from various raw materials.

In the present invention, the high thermal conductivity of the cured product of the composition imparts flame retardancy. In order to enhance the thermal conductivity, a filler other than amorphous silica is used as a filler. (Hereinafter referred to as “high heat conductive particles (c)”) are generally blended. As such particles, crystalline silica, alumina, silicon carbide, silicon nitride, aluminum nitride, boron nitride, titanium nitride, titanium carbide, beryllia, zirconia, inorganic single particles such as diamond, or Cu, Ag, Au, Ni, Pd, Pt, Zn, Al, Si, Fe, Mn, C
Various metals such as r, Mo, W, Ti, Zr, and Mg or two or more alloys are coated with an electrically insulating film such as silicon oxide, aluminum oxide, magnesium oxide, silicon nitride, aluminum nitride, boron nitride, and various resins. Composite particles, or composite particles obtained by coating silicon nitride, aluminum nitride, boron nitride, titanium nitride, or the like with silicon oxide, and the like. Among them, inorganic single particles such as crystalline silica and alumina are preferably used. Further, as the high thermal conductive particles (c), plural kinds of the above particles can be used in combination. Among these particles, those having a thermal conductivity of at least 1.5 w / mK measured at 23 to 100 ° C. are preferably used.

The content of the high thermal conductive particles (c) in the filler (C) in the present invention is not particularly limited as long as it provides the thermal conductivity of the cured product of the epoxy resin composition of the present invention. However, from the viewpoint of fluidity during molding of the epoxy resin composition, it is preferably 75% by weight or less, more preferably 50% by weight or less, and from the viewpoint of flame retardancy, it is preferably 5% by weight or more, more preferably 10% by weight or more. .

The shape and particle size of the filler (C) and the highly heat-conductive particles (c) in the present invention are not particularly limited, but in each case, 50% by weight of spherical particles having a size of 3 μm or more and 40 μm or less are contained in the filler (C). % Is preferable from the viewpoint of fluidity.

In the present invention, the average particle diameter means a particle diameter (median diameter) at which the cumulative weight becomes 50%. In the present invention, the proportion of the inorganic filler (C) is flame retardancy, moldability (flowability).
75 to 97% by weight, more preferably 80 to 96% by weight, further 85 to 95% by weight of the whole resin composition from the viewpoint of low stress property
Is preferred.

In the present invention, it is preferable from the standpoint of reliability that the filler is surface-treated in advance with a coupling agent such as a silane coupling agent, a titanate coupling agent, or an aluminate coupling agent.

The phosphate compound as the component (D) of the present invention is defined as “P—O—R” (R is an organic group) in chemical structure.
And usually a compound having a trivalent or pentavalent phosphorus atom is used. Phosphite (Phosphite) compounds and phosphonite (P
hosphonite) compound, phosphinite (Phosphinite)
There are compounds. On the other hand, those having a pentavalent phosphorus atom include a phosphate (Phosphate) compound and a phosphonate (P
hosphonate) compounds and phosphinate (Phosphinate) compounds. Among them, a phosphate compound having a pentavalent phosphorus atom is preferably used from the viewpoint of storage stability.

Further, among these phosphate ester compounds, those having an aromatic group as an organic group forming an ester are preferable from the viewpoint of flame retardancy and solder heat resistance.

Examples of such a phosphoric ester compound include triphenyl phosphate, resorcinol bis (diphenol) phosphate, 2-ethylhexyl diphenyl phosphate, and compounds described later.

Further, it is preferable that the compound contains a skeleton represented by the following formula (I).

Embedded image (In the formula, X may be the same or different, and means a monovalent or higher valent aromatic group.) More specifically, a compound represented by the following formula (V) is shown.

[0034]

Embedded image (In the above (V), R represents the same or different hydrogen atom or an alkyl group having 1 to 5 carbon atoms. Y represents a direct bond, an alkylene group, a phenylene group, -S-, -SO
Represents 2- or -CO-. Ar means an aromatic group substituted with the same or different aromatic group or organic group. k and m are each an integer of 0 or more and 2 or less, and k +
m is an integer of 0 or more and 2 or less. n is an integer of 0 or more. )

In the present invention, the amount of the phosphoric acid ester compound to be added to the components excluding the inorganic filler in the epoxy resin composition from the viewpoint of flame retardancy, solder heat resistance and moisture resistance reliability. The amount of phosphorus atoms in
The lower amount is preferably 0.01% by weight, more preferably 0.1% by weight.
% By weight, preferably 10% by weight and then 5% by weight as the above amount.

The molecular weight of the phosphate compound is 300 or more, more preferably 350 or more, and even 500 or more.
From the viewpoint of moisture resistance and solder heat resistance, it is preferable that the above-mentioned substances are contained in the phosphoric ester in an amount of 50% by weight or more. In the composition of the present invention, a phosphate ester having a trivalent phosphorus atom is blended in the composition, and a phosphate ester having a pentavalent phosphorus atom is obtained by oxidation in the composition. The effect is obtained. The epoxy resin composition of the present invention further includes a coloring agent such as carbon black, an ion scavenger such as hydrotalcite, an elastomer such as silicone rubber, an olefin copolymer, a modified nitrile rubber, a modified polybutadiene rubber, and a modified silicone oil. Optionally, a releasing agent such as a thermoplastic resin such as polyethylene, a long-chain fatty acid, a metal salt of a long-chain fatty acid, an ester of a long-chain fatty acid, an amide of a long-chain fatty acid, or paraffin wax, and a crosslinking agent such as an organic peroxide. Can be added.

In the present invention, a flame retardant such as a halogen compound such as a halogenated epoxy resin and various flame retardant aids such as antimony trioxide can be blended. However, since they tend to reduce the reliability as a semiconductor device, , Halogen atom and antimony atom are each 0.2% by weight or less, 0.1% by weight or less, and more preferably 0.2% by weight or less based on the resin composition.
It is preferable that the content is not more than 01% by weight, and further, it is not substantially blended.

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 co-kneader. Manufactured.

Here, the term "semiconductor device" refers to an electronic circuit (integrated circuit) formed by integrating and wiring transistors, diodes, resistors, capacitors, and the like on a semiconductor chip or substrate. Refers to an electronic component sealed with a resin composition. Then, a semiconductor device can be obtained by sealing a semiconductor element formed of a semiconductor chip using the epoxy resin composition of the present invention.

[0040]

The present invention will be described below in detail with reference to examples. Incidentally,% in the examples indicates% by weight.

Examples Comparative Examples The components shown in Table 1 were dry-blended by a mixer at the composition ratios shown in Table 2. This is adjusted to a roll surface temperature of 90.
The mixture was heated and kneaded for 5 minutes using a mixing roll at a temperature of 5 ° C., and then cooled and pulverized to produce an epoxy resin composition for semiconductor encapsulation.

Using this resin composition, molding was performed by low pressure transfer molding under the conditions of 175 ° C. and cure time of 2 minutes, and post-cured at 180 ° C. for 5 hours. Were evaluated for physical properties. The post-curing gives a cured product as referred to in the present invention.

Flame retardancy test: 5 "x 1/2" x 1/16 "
Was molded and post-cured, and the flame retardancy was evaluated according to the UL94 standard.

High-temperature reliability: 16 pi with a simulated element
nDIP (dual in-line package) sealing,
The high-temperature reliability at 200 ° C. of the semiconductor device was evaluated, and the time at which the cumulative failure rate reached 63% was determined as the high-temperature characteristic life.

PCBT (humidity reliability under voltage application): A 16-pin DIP semiconductor device mounted with a simulated element was prepared, and the PCBBT was evaluated at 140 ° C./85% RH and DC 20 V applied, and the cumulative failure rate was 63%. The time required was determined as the PCBT characteristic life.

Solder heat resistance: 160 pi with a chip size of 12 × 12 mm, on which a simulated element having Al deposited on the surface is mounted.
Twenty nQFPs (quad flat packages) are molded into a semiconductor device, humidified at 85 ° C./85% RT for a predetermined time, and heated in an IR reflow furnace at a maximum temperature of 245 ° C.
The number of external cracks generated was examined.

Thermal conductivity: The thermal conductivity k was calculated from the following formula using a cured product that had been molded and further post-cured. k = αρC _p (where α is the thermal diffusivity, ρ is the density, C _p is the specific heat) (The thermal diffusivity is measured at 25 ° C. by a laser flash method using TC-7000 manufactured by Vacuum Riko Co., Ltd.) Using Perkin Elmer DSC-2 at 30 ° C for 30-50 mg of sample
, Measured under a stream of dry nitrogen. Density is measured by Archimedes method. )

[Table 1]

Embedded image

[0048]

[Table 2]

[0049]

[Table 3]

Table 3 shows the results. As seen in Table 3, the epoxy resin composition of the present invention (Examples 1 to 10)
Indicates the flame retardancy and the moisture resistance reliability under applied voltage (PCB
T), excellent in high-temperature reliability and solder heat resistance.

On the other hand, Comparative Example 1, which has a high thermal conductivity but a filler (C) content of less than 75% by weight,
Poor flame retardancy and solder heat resistance.

Comparative Example 3 containing no phosphate compound (D) is inferior in flame retardancy.

Comparative Example 5, in which the thermal conductivity of the cured product is low, is inferior in flame retardancy.

Comparative Example 7, which contains a halogen-based flame retardant and a flame retardant aid, which is antimony oxide, has poor high-temperature reliability.

[0055]

According to the epoxy resin composition of the present invention,
A semiconductor device excellent in flame retardancy, high temperature reliability, moisture resistance reliability and solder heat resistance can be obtained.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 3/36 C08K 3/36 5/521 5/521 H01L 23/29 H01L 23/30 R 23/31

Claims (10)

[Claims] 1. An epoxy resin (A), a curing agent (B), a filler (C), and a phosphate compound (D) are contained as essential components, and the filler (C) is composed of amorphous silica and non-crystalline silica. An epoxy resin composition containing an inorganic filler other than crystalline silica and having a thermal conductivity of 1.2 W / mK or more after curing. 2. The epoxy resin composition according to claim 1, wherein the content of the filler (C) is 75 to 97% by weight of the resin composition. 3. The epoxy resin composition according to claim 1, wherein the phosphate compound (D) has a skeleton represented by the following chemical formula (I). Embedded image (In the formula, X may be the same or different, and means a monovalent or higher aromatic group.) 4. The content of a phosphorus atom derived from the phosphate compound (D) is 0.1 to 5% by weight based on a resin component excluding a filler in the epoxy resin composition. The epoxy resin composition according to any one of 1 to 3, above. 5. The epoxy resin composition according to claim 1, wherein the filler (C) contains one or more particles selected from crystalline silica, alumina, silicon nitride, and aluminum nitride as essential components. Stuff. 6. The epoxy resin composition according to claim 1, wherein the epoxy resin (A) essentially comprises a biphenyl type epoxy component having the structure of the following formula (II). Embedded image (However, R1 to R8 in the formula are a hydrogen atom, a carbon number 1 to 4
Represents an alkyl group or a halogen atom) 7. A curing agent (B) comprising a phenol compound having a structure represented by the following chemical formula (III) as an essential component.
The epoxy resin composition according to any one of claims 1 to 7, Embedded image (In the formula VI, m is an integer of 0 or more, X is a monovalent or divalent aromatic group which may be the same or different, Y is a monovalent or divalent group having a phenol group which may be the same or different.)
Valent aromatic group. ) 8. The epoxy resin composition according to claim 1, wherein the content of the filler (C) is 85 to 95% by weight. 9. The epoxy resin composition according to claim 1, which is used for encapsulating a semiconductor. 10. A semiconductor device in which a semiconductor element is sealed with the epoxy resin composition according to claim 9.