JP2600450B2 - Epoxy composition for semiconductor encapsulation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an epoxy composition for semiconductor encapsulation having excellent solder heat resistance, flame retardancy and high-temperature reliability.

<Conventional technology> Epoxy resins are excellent in heat resistance, moisture resistance, electrical properties, adhesiveness, etc., and can be imparted with various properties by formulation, so they are used as industrial materials such as coatings, adhesives and electrical insulating materials. Have been.

For example, as a method of sealing an electronic circuit component such as a semiconductor device, a hermetic seal made of metal or ceramic and a resin seal made of phenol resin, silicone resin, epoxy resin or the like have been conventionally proposed. However, resin sealing with epoxy resin is mainly used in terms of balance between economy, productivity, and physical properties.

On the other hand, recently, the density and automation of component mounting on printed circuit boards have been increasing, and instead of the conventional “insertion mounting method” in which lead pins are inserted into holes in the board, “components are soldered to the board surface” “Surface mounting method” has become popular. Along with this, packages are also shifting from conventional DIP (dual in-line packages) to thin FPPs (flat plastic packages) suitable for high-density mounting and surface mounting.

With the shift to the surface mounting method, the soldering process, which was not so much a problem in the past, has become a major 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 a soldering method in the surface mounting method, a solder bath immersion, heating with a saturated vapor of an inert gas (a vapor phase method), an infrared reflow method, and the like are used. In any case, the entire package is heated to a high temperature of 210 to 270 ° C. It will be heated.
Therefore, the package sealed with the conventional sealing resin has a problem that cracks occur in the resin portion at the time of soldering, the reliability is reduced, and the package cannot be used as a product.

Cracking in the soldering process is said to be caused by the moisture absorbed during the post-curing and during the mounting process becoming steam and expanding during explosion during soldering heating. Is used in a completely dried and sealed container for shipping.

Various studies have been made on improvements in the sealing resin. For example,
A method of adding an epoxy resin having a biphenyl skeleton and a rubber component (Japanese Patent Application Laid-Open No. 63-251419), a method of adding an epoxy resin having a biphenyl skeleton and fine powder particles having a particle diameter of 14 μm or less (Japanese Patent Application Laid-Open No. 1-87616) Gazette).

Further, in order to improve the moisture resistance of the sealing resin, a hydrotalcite-based compound is added (Japanese Patent Application Laid-Open No. 61-19625).
Has been proposed.

On the other hand, electronic components such as semiconductors are required to achieve flame retardancy according to UL standards, and therefore, flame retardants such as bromine compounds and antimony compounds are usually added to sealing resins.

<Problem to be Solved by the Invention> However, the method of enclosing the dry package in a container has disadvantages in that the manufacturing process and the handling of the product are complicated, and the product price is high.

In addition, resins improved by various methods have been gradually improving their effects, but are still insufficient. A method of adding an epoxy resin having a biphenyl skeleton and a rubber component (Japanese Patent Laid-Open No. 63-251419) and a method of adding an epoxy resin having a biphenyl skeleton and fine powder particles having a particle diameter of 14 μm or less (Japanese Patent Laid-Open No. 1-87616) Japanese Patent Application Laid-Open Publication No. H11-163,197) is effective in preventing cracks in a resin portion at the time of soldering, but has a problem that reliability at high temperatures is reduced.

High-temperature reliability guarantees the function of semiconductors in a high-temperature environment of 150 to 200 ° C, and is essential performance for semiconductors that generate a large amount of heat and semiconductors used around automobile engines.

It has been known that the problem of high-temperature reliability of the epoxy resin having a biphenyl skeleton is mainly caused by a flame retardant such as a bromine compound and an antimony compound added for imparting flame retardancy. For this reason, an epoxy resin for semiconductor encapsulation which is excellent in all of solder heat resistance, flame retardancy and high-temperature reliability has not been obtained.

An object of the present invention is to solve the problem of cracks generated in such a soldering step, and to prevent the reliability from being reduced at high temperatures due to the addition of a flame retardant, that is, a semiconductor package excellent in both solder heat resistance, flame retardancy and high temperature reliability. An object of the present invention is to provide a stopping epoxy composition.

<Means for Solving the Problems> The present inventors, by adding a hydrotalcite compound to an epoxy resin having a biphenyl skeleton,
The inventors have found that an epoxy composition for encapsulating a semiconductor meeting the above-mentioned objects and meeting the object can be obtained, and arrived at the present invention.

That is, the present invention relates to a resin composition comprising an epoxy resin (A), a curing agent (B), a fused silica (C), a hydrotalcite compound (D), a bromine compound (E), and an antimony compound (F). The epoxy resin (A) has the following formula (I) Wherein R ^{1 to} R ^{8 each} represent a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms or a halogen atom. The epoxy resin (a) having a skeleton represented by the following formula: The proportion of (C) is 79 to 90% by weight of the whole, and the proportion of the hydrotalcite-based compound (D) is
An object of the present invention is to provide a semiconductor sealing epoxy composition having a content of 0.01 to 10% by weight and a semiconductor device sealed thereby.

 Hereinafter, the configuration of the present invention will be described in detail.

The epoxy resin (A) in the present invention has the following formula (However, it is important that the epoxy resin (a) having a skeleton represented by R ^{1 to} R ⁸ represents a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms or a halogen atom. is there.

When the epoxy resin (a) is not contained, the effect of preventing the occurrence of cracks in the soldering step is not exhibited.

In the above formula (I), preferred specific examples of R _{1 to} R ₈ include a hydrogen atom, a methyl group, an ethyl group, a propyl group, an i
-Propyl group, m-butyl group, sec-butyl group, tert-
Examples thereof include a butyl group, a chlorine atom, and a bromine atom.

Preferred specific examples of the epoxy resin (a) in the present invention include 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'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetramethyl-2-
Bromobiphenyl, 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'-tetramethylbiphenyl, 4,4'
-Bis (2,3-epoxypropoxy) -3,3 ',-5,5'
-Tetrabutylbiphenyl and the like.

The epoxy resin (A) in the present invention can contain the above-mentioned epoxy resin (a) in combination with another epoxy resin other than the epoxy resin (a). Other epoxy resins that can be used in combination include, for example, cresol novolak type epoxy resin, phenol novolak type epoxy resin, various novolak type epoxy resins synthesized from bisphenol A and resorcin, bisphenol A type epoxy resin, linear aliphatic epoxy resin , Alicyclic epoxy resin, heterocyclic epoxy resin, halogenated epoxy resin and the like.

The ratio of the epoxy resin (a) contained in the epoxy resin (A) is not particularly limited, and the effect of the present invention is exhibited if the epoxy resin (a) is contained as an essential component, but a more sufficient effect is obtained. In order to exert the effect, the epoxy resin (a) is usually added to the epoxy resin (A) by 50% by weight.
As described above, it is necessary that the content is preferably 70% by weight or more.

In the present invention, the compounding amount of the epoxy resin (A) is usually 4 to 20% by weight, preferably 6 to 18% by weight.

The curing agent (B) in the present invention is an epoxy resin (A)
There is no particular limitation as long as it is cured by reacting with phenol novolak resin, cresol novolak resin, bisphenol A
Novolak resins synthesized from rosin and resorcinol, various polyhydric phenol compounds, acid anhydrides such as maleic anhydride, phthalic anhydride, and pyromellitic anhydride, and aromatic amines such as metaphenylenediamine, diaminodiphenylmethane, and diaminodiphenylsulfone. Is mentioned. For sealing semiconductor devices, a phenolic 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.

In the present invention, the amount of the curing agent (B) is usually from 2 to 15
% By weight, preferably 3 to 10% by weight. Furthermore, 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 0.7 to 1.3, particularly 0.8 to 1.2, from the viewpoint of mechanical properties and moisture resistance. It is preferably within the range.

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. -Methylimidazole, 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-
Methylimidazole, imidazole compounds such as 2-eptadecylimidazole, triethylamine, benzyldimethylamine, α-methylbenzyldimethylamine,
Tertiary ammine compounds such as 2- (dimethylaminomethyl) phenol, 2,4,6-tris (dimethylaminomethyl) phenol, 1,8-diazabicyclo (5,4,0) undecene-7, zirconium tetramethoxide, Organometallic compounds such as zirconium tetrapropoxide, tetrakis (acetylacetonato) zirconium, tri (acetylacetonato) aluminum and triphenylphosphine, trimethylphosphine, triethylphosphine;
Organic phosphine compounds such as tributylphosphine, tri (p-methylphenyl) phosphine, and tri (nonylphenyl) phosphine are exemplified. Of these, organic phosphine compounds are preferred from the viewpoint of moisture resistance, and triphenylphosphine is particularly preferably used.

These curing catalysts may be used in combination of two or more depending on the use, and the addition amount thereof is preferably in the range of 0.5 to 5 parts by weight based on 100 parts by weight of the epoxy resin (A).

The fused silica (C) in the present invention means amorphous silica having a true specific gravity of 2.3 or less. The production does not necessarily have to go through a 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 (C) are not particularly limited, but 99 to 50% by weight of crushed fused silica having an average particle size of 10 μm or less and 1 to 50% by weight of spherical fused silica having an average particle size of 40 μm or less.
Fused silica C is preferably used because it has a large effect of improving solder heat resistance and has good fluidity. Above all, 99 to 50% by weight, particularly 99 to 70% by weight, of crushed fused silica having an average particle size of 10 μm or less, particularly 3 to 10 μm, and spherical fused silica 1 to 50 having an average particle size of 40 μm or less, particularly 0.1 to 40 μm. Most preferably, fused silica (C) consisting of 1% to 30% by weight is used. Here, the average particle diameter means a particle diameter (median diameter) at which the cumulative weight becomes 50%. When two or more kinds of crushed or spherical fused silica having different average particle diameters are used in combination, the mixture is crushed or spherical. It means the average particle size of fused silica.

In the present invention, the ratio of the fused silica (C) is 79% of the total.
To 90% by weight, and more preferably 79 to 88% by weight. If the fused silica (C) is less than 79% by weight, the solder heat resistance is insufficient, and if it exceeds 90% by weight, the fluidity is insufficient.

The hydrotalsato compound (D) in the present invention comprises:
It is a composite metal compound represented by the following formula (II) or (III).

_{Mg x Al y (OH) 2x} + 3y-nz A z · mH 2 O ...... (II) Mg x Al y O (2x + 3y) / 2 ...... (III) ( provided that, A is an n-valent anion A ^{n -} functional group capable of generating,
n is an integer of 1 to 3, x, y and z are 0 <y / x ≦ 1, 0
0 or a positive number in a relationship of ≦ z / y <1.5, and m indicates 0 or a positive number. ) The formula (II), the n-valent capable of forming a functional group A anions A ^n- preferred as specifically, F ^-, Cl ^-, Br
^{-, I -, OH -,} HCO 3 -, CHμCOO -, HCOO -, CO 3 2-, SO 4 2-,
(COO _{^-) 2,} tartrate [CH (OH) COO ^-] _2, citrate ion [C (OH) COO ^-] (CH ₂ COO _{^-) 2,} salicylate _{C 6 H 4 (OH) COO} - , etc. No. Above all, CO
₃ ^2- is particularly preferred.

The hydrotalcite-based compound (D) represented by the above formula (III), for example, produced by baking the hydrotalcite-based compound (D) represented by the above formula (II) at 400 to 900 ° C. .

Preferred specific examples of the hydrotalcite-based compound (D) include Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ · 3.5 H ₂ O and Mg _4.5 Al ₂ (O
H) ₁₃ CO ₃ , Mg ₅ Al _1.5 (OH) ₁₃ CO ₃ · 3.5 H ₂ O, Mg ₅ Al _1.5 (O
H) ₁₃ CO ₃ , Mg ₆ Al ₂ (OH) ₁₆ CO ₃ · 4H ₂ O, Mg ₆ Al ₂ (OH) ₁₆ C
O ₃ , Mg _0.56 Al _0.35 O _1.175 , Mg _0.7 Al _0.3 O _1.15 , Mg _0.75 A
l _0.25 O _1.125 , Mg _0.8 Al _0.2 O _{1.1 and the} like.

In the present invention, the addition amount of the hydrotalcite-based compound (D) is 0.01 to 10% by weight, preferably 0.02 to 5% by weight, and particularly preferably 0.05 to 2% by weight. Addition amount
If it is less than 0.01% by weight, the effect of improving high-temperature reliability is insufficient, and if it exceeds 10% by weight, solder heat resistance is reduced.

The bromine compound (E) and the antimony compound (F) in the present invention are usually added as a flame retardant to the epoxy composition for semiconductor encapsulation, and are not particularly limited, and known compounds can be used.

Preferred specific examples of the bromine compound (E) include brominated epoxy resins such as a brominated bisphenol A type epoxy resin and a brominated phenol novolak type epoxy resin, a brominated polycarbonate resin, a brominated polystyrene resin,
Brominated polyphenylene oxide resin, tetrabromobisphenol A, decabromodiphenyl ether and the like can be mentioned. Among them, brominated epoxy resins such as brominated bisphenol A type epoxy resin and brominated phenol novolak type epoxy resin are particularly preferably used.

The addition amount of the bromine compound (E) is preferably from 0.1 to 5% by weight in terms of bromine atom in terms of flame retardancy and high-temperature reliability. Particularly preferably, it is 0.2 to 2% by weight.

In addition, a preferable specific example of the antimony compound (F) is antimony trioxide. The addition amount of the antimony compound (F) is preferably 0.1 to 10% by weight of the whole in view of flame retardancy and high-temperature reliability. Particularly preferably 0.2 to
4% by weight.

In the epoxy composition for semiconductor encapsulation of the present invention, as a filler, besides fused silica (C), crystalline silica, calcium carbonate, magnesium carbonate, alumina, magnesia, clay, talc, calcium silicate, titanium oxide, antimony oxide, Asbestos, glass fibers and the like can be added.

In the present invention, it is preferable from the viewpoint of reliability that a filler such as fused silica (C) is subjected to a surface treatment in advance with a coupling agent such as a silane coupling agent or a titanate coupling agent. As the coupling agent, a silane coupling agent such as epoxy silane, amino silane, and mercapto silane is preferably used.

The epoxy composition for semiconductor encapsulation of the present invention includes a coloring agent such as carbon black, iron oxide, silicone rubber, a modified nitrile rubber, a modified polybutadiene rubber, an elastomer such as a styrene blockon copolymer, and a thermoplastic resin such as polyethylene. A releasing agent such as 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, paraffin wax and a crosslinking agent such as an organic peroxide can be optionally added.

The epoxy compound for semiconductor encapsulation 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-screw or twin-screw extruder and a co-kneader. Manufactured.

<Example> Hereinafter, the present invention will be specifically described with reference to examples.

Examples 1 to 9, Comparative Examples 1 to 7 A fused silica (C) shown in Table 1 and a hydrotalcite-based compound (D) shown in Table 2 were mixed with a reagent at a composition ratio shown in Table 2, respectively. By dry blending.
This was melt-kneaded using a twin-screw extruder having a barrel setting temperature of 90 ° C., and then cooled and pulverized to produce an epoxy composition for semiconductor encapsulation.

Using this composition, low-pressure transfer molding
The composition was molded at 175 ° C. × 2 minutes, post-cured at 175 ° C. × 8 hours, and the physical properties and moldability of each composition were measured by the following physical property measuring methods.

Solder heat resistance: A semiconductor device equipped with a simulated element with A1 vapor deposition on the surface, 20 28-pin SOP, molded and post-cured, 85 ℃
After humidifying at / 85% RH for 50 hours, the SOP with cracks was determined to be defective by immersion in a solder bath heated to 260 ° C. for 10 seconds.

Flame retardancy: 5 "x 1/2" x 1/16 "combustion test specimen
Post cure was performed and the flame retardancy was evaluated according to UL94 standard.

High-temperature reliability: 20 pins using 28-pin SOP after solder heat resistance evaluation
The high-temperature reliability was evaluated at 0 ° C., and the time at which the cumulative failure rate reached 50% was determined, and the high-temperature life was determined.

As seen from Table 3, the epoxy compositions for semiconductor encapsulation of the present invention (Examples 1 to 9) are excellent in solder heat resistance, flame retardancy and high-temperature reliability.

On the other hand, Comparative Example 2 containing no epoxy resin (a) is inferior in solder heat resistance and Comparative Examples 3 to 5 containing no bromine compound (E) and / or antimony compound (F).
Is inferior in flame retardancy.

Comparative Example 9, which does not contain the hydrotalcite-based compound (D), is inferior to Example 1 in solder heat resistance and high-temperature reliability.

Further, when the content of the fused silica (D) was out of the range of the present invention, the solder heat resistance was poor.

<Effect of the Invention> The epoxy composition for encapsulating a semiconductor of the present invention contains a specific epoxy resin, a curing agent, a specific amount of fused silica, a hydrotalcite-based compound, a bromine compound and an antimony compound, and thus has a solder heat resistance. Excellent in flame retardancy and high temperature reliability.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location H01L 23/29 H01L 23/30 R 23/31

Claims (3)

(57) [Claims] 1. A resin composition comprising an epoxy resin (A), a curing agent (B), a fused silica (C), a hydrotalcite compound (D), a bromine compound (E) and an antimony compound (F). The epoxy resin (A) has the following formula (I) (Wherein R ^{1 to} R ⁸ represent a hydrogen atom, a lower alkyl group having 1 to 4 carbon atoms or a halogen atom.) The epoxy resin (a) having a skeleton represented by the following formula: A semiconductor-free epoxy composition having a proportion of 79 to 90% by weight and a proportion of the hydrotalcite-based compound (D) of 0.01 to 10% by weight based on the whole. 2. The method according to claim 1, wherein the fused silica (C) comprises 99 to 50% by weight of crushed fused silica having an average particle size of 10 μm or less and 1 to 50% by weight of spherical fused silica having an average particle size of 40 μm or less. Epoxy composition for semiconductor encapsulation. 3. A semiconductor device encapsulated with the epoxy composition for semiconductor encapsulation according to claim 1.