JPH11269348A - Epoxy resin composition for sealing semiconductor and semiconductor device using the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition with excellent moldability, reliability and flame retardancy and useful for sealing semiconductor devices, by essentially including an epoxy resin, a hardener, a specific metal oxide, a borate and other(s) so as to dispense with a bromine-based flame retardant and antimony. SOLUTION: This composition is obtained by essentially including (A) an epoxy resin (pref. biphenyl-type one), (B) an hardener (pref. a xylylene group- bearing aralkylphenolic resin or the like), (C) an accelerator (pref. an adduct of tri-p-tolylphosphine and benzoquinone, or the like), (D) pref. 0.05-5 wt.% of a metal oxide selected from zinc oxide, tin oxide, molybdenum oxide and tungsten oxide, (E) pref. 0.5-10 wt.% of a borate (pref. zinc borate or the like), and (F) pref. 80-95 wt.% of an inorganic filler such as fused silica.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to flame retardancy, moldability,
The present invention relates to a sealing material excellent in reliability and a resin-sealed semiconductor device using the same.

[0002]

2. Description of the Related Art Resin encapsulation is mainly used for encapsulating semiconductor devices in terms of productivity and cost. As this sealing resin, an epoxy resin composition excellent in electrical characteristics, cost, workability and the like is mainly used. However, since epoxy resins have insufficient flame retardancy, brominated epoxy resins are added to improve flame retardancy. An antimony compound (antimony trioxide, antimony pentoxide, etc.) having a synergistic effect is used in combination with the brominated flame retardant. In recent years, from the viewpoint of environmental protection, the use of brominated flame retardants suspected of producing dioxin during combustion and antimony, which has been pointed out as a potential carcinogen, has been increasingly required. To meet this demand, various alternative flame retardants have been studied. For example, metal hydrates such as aluminum hydroxide and magnesium hydroxide must be added in large amounts in order to exhibit sufficient flame retardancy, resulting in deterioration of the curability, strength, etc. of the resin composition. I will. In addition, various types of phosphate ester flame retardants (including those used in combination with nitrogen) have been proposed, but in reality, none of them meet the requirements of semiconductor encapsulation applications in terms of moldability and reliability.

[0003] Various proposals have already been made for applying a red phosphorus-based flame retardant to an epoxy resin for semiconductor encapsulation. For example, an epoxy resin composition for semiconductor encapsulation using a red phosphorus-based flame retardant characterized in that the surface layer is made of SixOy (JP-A-7-157542), bismuth oxide,
An epoxy resin composition for semiconductor encapsulation using a red phosphorus-based flame retardant coated with a mixture of bismuth hydroxide and bismuth nitrate (JP-A-8-100108), a red phosphorus-based flame retardant, and an ion scavenger were used. Epoxy resin composition for semiconductor encapsulation (JP-A-8-151427), epoxy resin composition for semiconductor encapsulation using red phosphorus-based flame retardant and boron-based flame retardant (JP-A-8-151505), surface Resin composition for semiconductor encapsulation using red phosphorus coated with phenol resin and aluminum hydroxide (Japanese Patent Application Laid-Open No. 9-165495)
Japanese Patent Application Laid-Open No. 9-90), an epoxy resin composition for semiconductor encapsulation using red phosphorus whose surface is coated with a phenol resin and aluminum hydroxide and defining an epoxy / hardener equivalent ratio, a glass transition temperature, and a coefficient of thermal expansion. No. 227765) has been proposed, but has not always satisfied the strict requirements of semiconductor applications. Simply covering the surface layer with a mixture of SixOy, bismuth oxide, bismuth hydroxide, and bismuth nitrate is inevitable in reducing the moisture resistance due to phosphate ions eluted from red phosphorus, and a sufficient effect can be obtained even by using an ion scavenger. It is difficult. The combined use of red phosphorus and a boron-based flame retardant has an Ajinata effect in flame retardancy and is relatively good in terms of reliability, but has problems such as reduced curability and release properties. . Also, red phosphorus alone whose surface is coated with aluminum hydroxide and a phenolic resin is unsuitable for use in semiconductors due to reduced moisture resistance and high-temperature storage properties, as described above. When a metal hydrate such as aluminum hydroxide or magnesium hydroxide, or a metal hydrate such as zinc borate is used alone, it must be added in a large amount in order to exhibit sufficient flame retardancy. However, the curability and strength of the resin composition are deteriorated. The effect of using metal oxides and metal hydrates in combination has been reported previously (Mitsubishi Electric Wire & Cable Times No. 75, April 1988), and oxides and hydrates of a specific group in the periodic table (Japanese Patent Application Laid-Open No. Hei 9-100377) has been proposed, but it is difficult to achieve both flame retardancy and moldability, and this does not meet the strict requirements for semiconductor encapsulation applications.

[0004]

SUMMARY OF THE INVENTION The present invention relates to an epoxy resin composition for semiconductor encapsulation which does not contain a bromine-based flame retardant or antimony, is excellent in moldability, reliability and flame retardancy, and a semiconductor device using the same. The purpose is to provide. Alternatives to brominated flame retardants include metal oxides and metal hydrates. Metal oxide-based flame retardants include ZnO, Sn
O, MoO3, Fe2 O3, CUO, NiO and the like are widely known. However, when these metal oxides are used alone, the curability, releasability, and reliability tend to decrease in the epoxy resin composition for semiconductor encapsulation, and the flame retardancy is sufficient. Absent. On the other hand, aluminum hydroxide, magnesium hydroxide, and the like are widely known as metal hydrate-based flame retardants. However, in order to satisfy the flame retardancy by using these metal hydrates alone, it is necessary to add a large amount of the metal hydrate. In the case of an epoxy resin for semiconductor encapsulation, the curability and the releasability are reduced, and the resistance to the resin is reduced. Reflow cracking property also decreases. In particular, magnesium oxide, as a metal hydrate, has a large flame-retarding effect and can achieve the target flame retardancy with a relatively small amount of addition compared to other metal hydrates. The resin has low affinity with the epoxy resin to be used, and a releasability defect called a whitening phenomenon occurs during molding, making it difficult to apply to mass production. The present inventors have conducted intensive studies to solve these problems, and as a result, in a specific combination of a metal oxide and a borate, the amount of addition can be reduced by a synergistic effect, and the epoxy for semiconductor encapsulation can be reduced. The present inventors have found that the curability, release properties, moisture resistance reliability, and high-temperature storage reliability of the resin are improved, and that the reflow crack resistance can be maintained at a level equal to or higher than the current level, and the present invention has been achieved.

[0005]

That is, the present invention comprises an epoxy resin, a curing agent, a curing accelerator, a metal oxide selected from zinc, tin, molybdenum or tungsten, a borate, and an inorganic filler as essential components. The present invention relates to an epoxy resin composition for semiconductor encapsulation and a semiconductor device using the same.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The epoxy resin used in the present invention is not limited as long as it is generally used in an epoxy resin molding material for encapsulating electronic parts. For example, a phenol novolak type epoxy resin is exemplified. resin,
Epoxidized novolak resins of phenols and aldehydes, including orthocresol novolak type epoxy resins, diglycidyl ethers such as bisphenol A, bisphenol F, bisphenol S, alkyl-substituted biphenols, diaminodiphenylmethane,
Glycidylamine-type epoxy resins obtained by the reaction of polyamines such as isocyanuric acid and epichlorohydrin, linear aliphatic epoxy resins obtained by oxidizing olefin bonds with a peracid such as peracetic acid, and alicyclic epoxy resins. Any number of these can be used in combination. Above all, when an alkyl-substituted biphenol type diepoxy resin such as 4,4′-bis (2,3-epoxypropoxy) -3,3 ′, 5,5′-tetramethylbiphenyl is used, adhesiveness and hygroscopicity are good. At the same time, the epoxy resin has a particularly low viscosity at the time of melting, so that the compounding amount of the filler can be greatly improved. As a result, a molding material having excellent reflow crack resistance and moisture resistance can be obtained, and it is preferable to use these epoxy resins in an amount of 60% by weight or more based on the total amount of the epoxy resins used. The reason for this is that if the content is less than 60% by weight, the epoxy resin does not exhibit the characteristics of low moisture absorption and high adhesiveness, and has little effect on solder resistance. Examples of the epoxy resin include those obtained by epoxidizing 4,4′-bishydroxy 3,3 ′, 5,5′-tetramethylbiphenyl using epichlorohydrin.

As the curing agent used in the present invention, acid anhydrides, amines, phenol compounds and the like can be used. Among them, phenol compounds are preferable.
Examples of these phenol compounds include phenols such as phenol, cresol, xylenol, resorcin, catechol, bisphenol A, bisphenol F or α.
Resins obtained by condensing or co-condensing naphthols such as naphthol, β-naphthol, dihydroxynaphthalene and aldehydes such as formaldehyde, acetaldehyde, propionaldehyde, benzaldehyde and salicylaldehyde under an acidic catalyst, polyparavinylphenol resin, phenol And phenol-aralkyl resins having a xylylene group synthesized from dimethoxyparaxylene, and may be used alone or in combination of two or more.
Among them, a phenol-aralkyl resin having a xylylene group or a structural formula (1)

Embedded image When the phenolic resin represented by the formula (1) is used, the adhesiveness and the hygroscopicity are good, and at the same time, the viscosity of the phenolic resin at the time of melting is low, so that the amount of the filler can be increased. As a result, a molding material excellent in reflow crack resistance and moisture resistance is obtained, and it is preferable to use 60% by weight or more based on the total amount of the curing agent used. The reason is that
If the content is less than 0% by weight, the phenolic resin does not exhibit the characteristics of low hygroscopicity and high adhesiveness, and has little effect on solder resistance. Further, 4,4'-bis (2,3-epoxypropoxy) -3,3 ', 5,5'
-By using in combination with an alkyl-substituted biphenol type diepoxy resin such as tetramethylbiphenyl,
Particularly excellent solder resistance is obtained, and the equivalent ratio between the epoxy resin (A) and the curing agent (B) is not particularly limited.
It is preferable to set it in the range of 7 to 1.3.

In order to accelerate the reaction between the epoxy resin (C) used in the present invention and the curing agent, general curing accelerators can be used widely. Particularly, when a phenol compound is used as the curing agent, Examples of the curing accelerator include 1,8-diazabicyclo (5,4,
0) diazabicycloalkenes such as undecene-7 and derivatives thereof, tertiary amines such as triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, tris (dimethylaminomethyl) phenol, 2-methylimidazole, Imidazoles such as -phenylimidazole, 2-phenyl-4-methylimidazole, and 2-heptadecylimidazole; organic phosphines such as tributylphosphine, methyldiphenylphosphine and triphenylphosphine;
Tetra-substituted phosphonium / tetra-substituted borate such as triphenylphosphonium-triphenylborane, triphenylphosphine-benzoquinone adduct, triparatolylphosphine-benzoquinone adduct, tetraphenylphosphonium / tetraphenylborate, 2-ethyl-4
And tetraphenylboron salts such as N-methylimidazole / tetraphenylborate and N-methylmorpholine / tetraphenylborate, which can be used alone or in combination. Among them, triphenylphosphine-benzoquinone is preferable in terms of balance of properties. The adduct, triparatolylphosphine-benzoquinone adduct is preferred.

A method for synthesizing the above-mentioned benzoquinone adduct will be described below using triparatolylphosphine as an example. 1. 44.2 g of triparatolylphosphine was added to acetone 1
Dissolve in 20 g. 2. 17.6 g of p-benzoquinone are dissolved in 80 g of acetone. 3. Mix the solutions of 1 and 2 at room temperature to 80 ° C. 4. The precipitated crystals are filtered out and dried to obtain an adduct of triparatolylphosphine and benzoquinone. In addition, it is necessary to use an inorganic filler as a filler from the viewpoint of reducing hygroscopicity and improving strength. Examples of the inorganic filler include fused silica, crystalline silica, alumina, zircon, calcium silicate, calcium carbonate, and silicon carbide. , Boron nitride, beryllia, zirconia, and the like, or spherical beads thereof, potassium titanate, silicon carbide,
One or more kinds of single crystal fibers such as silicon nitride and alumina, glass fibers and the like can be blended. Further, examples of the inorganic filler having a flame-retardant effect include aluminum hydroxide and zinc borate, and these can be used alone or in combination. The amount of the inorganic filler is preferably 70% by weight or more from the viewpoints of hygroscopicity, reduction of linear expansion coefficient and improvement of strength. Among the above-mentioned inorganic fillers, fused silica is preferred from the viewpoint of reducing the coefficient of linear expansion, and alumina is preferred from the viewpoint of high thermal conductivity, and the filler shape is spherical from the viewpoint of fluidity during molding and mold abrasion. Is preferred. Other additives include higher fatty acids, higher fatty acid metal salts, release agents such as ester waxes and polyolefin waxes, coloring agents such as carbon black, epoxy silane, amino silane, ureido silane, vinyl silane, alkyl silane, organic titanate, A coupling agent such as aluminum alcoholate can be used. Among the above coupling agents, aminosilane is preferred from the viewpoint of flame retardancy and curability, and among them, γ-anilinopropyltrimethoxysilane, γ-anilinopropyltriethoxysilane, γ-anilinopropylmethyldimethoxysilane , Γ-anilinopropylmethyldiethoxysilane and the like are particularly preferred from the viewpoint of adhesion to a lead frame, moisture resistance, and moldability.

The metal oxide used in the present invention includes:
Oxides of zinc, tin, molybdenum or tungsten may be used alone or in combination of two or more. Particularly, molybdenum oxide and zinc oxide are preferably used from the viewpoint of flame retardancy and curability. The content of the metal oxide in the resin composition is 0.05 to 5% based on the total composition.
(Weight) is preferred. If it is less than 0.05%, the flame retardancy is insufficient, and if it is more than 5%, a problem is likely to occur in the curability. A particularly preferred range is from 0.1 to 2.0% by weight.
The content of borate is 0.5 to 10%. 0.5
If less than 10%, no combined effect is observed and 10%
If it is larger, problems tend to occur in the fluidity. A particularly preferred range is from 1.0 to 5% by weight. Among them, zinc borate (2
ZnO ₃ B ₂ O ₃ 5H ₂ O) is recommended. This is, for example, FIREBRAKE 29 manufactured by Borax Japan Co., Ltd.
It is available as 0. As other additives, colorants (such as carbon black), modifiers (such as silicone and silicone rubber), and ion trappers (such as hydrotalcite and antimony-bismuth) can be used. As a method of producing a molding material using the above-mentioned raw materials, a raw material mixture having a predetermined composition is sufficiently mixed by a mixer or the like, and then kneaded by a hot roll, an extruder, or the like, and then cooled and pulverized to form. Materials can be obtained.

[0011] As a method for encapsulating an electronic component using the epoxy resin composition obtained by the present invention, a low pressure transfer molding method is the most common, but it is also possible to employ a method such as injection molding, compression molding, casting or the like. It is possible.
The epoxy resin composition manufactured using the above means is environmentally friendly because it does not contain a brominated flame retardant and antimony compound, and has excellent moldability and reliability,
It can be suitably used for sealing of IC, LSI and the like.

[0012]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. Examples 1 to 5 and Comparative Examples 1 to 6 First, using various materials shown in Tables 1 and 2,
2 and Comparative Examples 1 to 5 were produced by premixing (dry blending) each material, kneading with a biaxial roll (roll surface temperature about 80 ° C.) for 10 minutes, and cooling and pulverizing. The materials used in the examples and comparative examples are as follows. Biphenyl type epoxy resin: YX-400 made by Yuka Shell
0H Phenol / aralkyl resin: XL-225 manufactured by Mitsui Chemicals Co., Ltd. Curing agent having biphenyl skeleton: MEH-7 manufactured by Meiwa Kasei
851 Epoxysilane: KBM-403 manufactured by Shin-Etsu Silicone Polyethylene Wax: PED-191 manufactured by Hoechst Company Brominated epoxy resin: ESB-400 manufactured by Sumitomo Chemical Co., Ltd. Magnesium hydroxide: Kisuma 5J manufactured by Kyowa Chemical Co., Ltd. Fused silica: Micron S-CO spherical product

[0013]

[Table 1]

[0014]

[Table 2]

Using this sealing material, using a transfer molding machine, a mold temperature of 180 ° C. and a molding pressure of 70 kgf / cm.
^2. Each test was conducted under the condition of a curing time of 90 seconds. Spiral flow was measured by EMM11-66. Hot hardness was measured by a Shore hardness tester. Further, using this sealing material, a semiconductor element was molded by a transfer molding machine under the same conditions, and after post-curing (175 ° C./5 h), moisture resistance and solder heat resistance were evaluated. The semiconductor device used for moisture resistance is SO
P-28 pin, after pretreatment of 85 ° C / 85RH% for 72 hours and moisture absorption at 215 ° C / 90 seconds (VPS), PCT
(21 ° C./2 atm), and the presence or absence of disconnection of the wiring on the chip was evaluated. The semi-suspension device used for high-temperature storage is SOP-
The number of pins was 28, and the bonding strength of the gold wire after standing at 175 ° C. for a predetermined time was measured and judged. The semiconductor device used for soldering heat resistance is a resin-encapsulated semiconductor device with QFP 80 pins (outer dimensions 20 × 14 × 2.0 mm). The lead frame has a chip size of 8 × 10 mm using 42 alloy material (no processing). The solder heat resistance of the resin-encapsulated semiconductor device thus obtained was 125 ° C./2
After baking for 4 hours, moisture absorption was performed at 85 ° C./85% RH for a predetermined time, and then a determination was made based on the crack occurrence rate of the resin-encapsulated semiconductor device when the treatment was performed at 240 ° C./10 sec. Table 3 summarizes the above test results.

[0016]

[Table 3]

[0017]

According to the present invention, a metal oxide and a borate are blended as essential components as a flame retardant in a semiconductor element sealing epoxy resin composition containing an epoxy resin, a curing agent and an inorganic filler as main components. This makes it possible to obtain a molding material having excellent reliability and having a very small influence on the environment. By sealing a semiconductor element using this molding material, a semiconductor device having excellent reliability and flame retardancy can be obtained.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 3/38 C08K 3/38 H01L 23/29 H01L 23/30 R 23/31

Claims (8)

[Claims] 1. An epoxy resin (B) a curing agent (C) a curing accelerator (D) a metal oxide selected from zinc, tin, molybdenum or tungsten (E) a borate and (F) an inorganic filler An epoxy resin composition for semiconductor encapsulation comprising, as an essential component. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the curing accelerator is an adduct of triparatolylphosphine and benzoquinone. 3. The content of the inorganic filler is 80 to 95% by weight, the content of the metal oxide is 0.05 to 5% by weight, and the content of the borate is 0.5 to 10% by weight. 3. The epoxy resin composition for semiconductor encapsulation according to 1 or 2. 4. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the epoxy resin is a biphenyl type epoxy resin. 5. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the curing agent is a phenol aralkyl resin having a xylylene group. 6. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the curing agent is a phenol resin represented by the structural formula (1). Embedded image 7. The method according to claim 7, wherein the borate is zinc borate (2ZnO ₃ B ₂ O ₃ 5).
H ₂ O) semiconductor encapsulating epoxy resin composition according to either of claims 1 to 6 is. 8. An epoxy resin-encapsulated semiconductor device in which a semiconductor element is encapsulated by using the epoxy resin composition for encapsulating a semiconductor according to claim 1.