JP3370271B2 - Epoxy resin composition for encapsulation and semiconductor device - 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 used for protection and encapsulation of electric / electronic parts such as diodes, transistors and integrated circuits and semiconductor devices, and a semiconductor device using the same.

[0002]

2. Description of the Related Art As a sealing method for electric / electronic parts such as diodes, transistors and integrated circuits, and semiconductor devices, for example, a sealing method using epoxy resin or silicon resin, glass, metal, ceramic or the like is used. However, in recent years, resin encapsulation by low-pressure transfer molding using epoxy resin, which has improved reliability and can be mass-produced and has cost advantages, has become mainstream. is occupying.

In the encapsulation method using this epoxy resin, a molding material composed of an o-cresol novolac type epoxy resin as a base resin component and an epoxy resin composition using a phenol novolac resin as a curing agent is generally used. Has been done. However, IC, LSI, V
With the increase in density and integration of electronic parts such as LSIs and semiconductor devices, conventional epoxy resin compositions cannot always satisfactorily meet the demand for thinner mold resins.

For example, in a surface mounting device, the device itself is directly immersed in solder during mounting,
Since it is rapidly exposed to high temperature and harsh environment, the occurrence of package cracks is unavoidable. That is, when the moisture absorbed during storage after molding is rapidly vaporized and expanded when exposed to high temperatures, the sealing resin cannot withstand this and cracks occur in the package.

In order to solve these problems, the encapsulating epoxy resin composition has been studied for improvement in heat resistance, adhesiveness, etc., and these characteristics have been actually improved. . For example, the use of a biphenyl type epoxy resin having a biphenyl skeleton has been studied and improved.

[0006]

However, when a biphenyl type epoxy resin is used, the rigidity at the time of molding and curing cannot be ensured due to a decrease in the reaction cross-linking density, deactivation of the curing accelerator due to water, etc. It caused troubles, especially mold release troubles. Therefore, an object of the present invention is to provide an epoxy resin composition using a biphenyl type epoxy resin,
An epoxy resin composition for encapsulation, which can sufficiently secure rigidity during molding and curing, and is unlikely to cause molding problems such as mold release problems.
It is to provide a semiconductor device using this.

[0007]

In order to solve the above problems, the inventors of the present invention have made extensive studies, and as a result, have found the following and have completed the present invention. That is, an epoxy resin composition using a biphenyl type epoxy resin,
When the following predetermined amount of an anhydride of a carboxylic acid having at least one cyclo ring is added as an additive, compared with the conventional encapsulating epoxy resin composition using a biphenyl type epoxy resin, the use of the biphenyl type epoxy resin is This means that the decrease in the reaction cross-linking density and the deactivation of the curing accelerator due to water are prevented, and as a result, the rigidity during molding and curing is sufficiently secured, and molding troubles such as mold release troubles are less likely to occur.

That is, the epoxy resin composition for sealing according to the present invention comprises an epoxy resin containing at least a biphenyl type epoxy resin having a biphenyl skeleton represented by the following structural formula (1), a curing agent, and a curing accelerator. In the epoxy resin composition for encapsulation containing a filler as an essential component, the curing agent comprises a phenol resin ,
The epoxy resin may be included in an amount of 0.5 to 1.5 equivalents, the curing accelerator may be included in an amount of 0.25 to 5% by weight based on the total amount of the epoxy resin composition, and at least 1 as an additive. It is characterized in that it contains 0.1 to 3.0% by weight of an anhydride of a carboxylic acid having one cyclo ring with respect to the total amount of the resin.

[0009]

[Chemical 4]

(In the formula, R ^{1 to} R ⁸ are hydrogen atoms or alkyl groups having 1 to 5 carbon atoms.) In the semiconductor device according to the present invention, a semiconductor element is sealed with the epoxy resin composition for sealing according to the present invention. I will do it.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION (Epoxy Resin Composition) A biphenyl type epoxy resin used as an epoxy resin has a biphenyl skeleton represented by the structural formula (1). In formula (1), R ^{1 to} R ⁸ are not particularly limited as long as they are hydrogen atoms or alkyl groups having 1 to 5 carbon atoms.

As the epoxy resin, the above biphenyl type epoxy resin is always used, but other epoxy resins may be used together. The epoxy resin that can be used in combination with the biphenyl type epoxy resin is not particularly limited as long as it has two or more epoxy groups in one molecule, but a preferable example is the following structural formula (2):

[0013]

[Chemical 5]

A dicyclopentadiene type epoxy resin having a dicyclopentadiene skeleton represented by, a cresol (novolak) type epoxy resin, and a bisphenol type (A
Type, F type, S type, etc.) epoxy resin, triphenylmethane type epoxy resin, brominated epoxy resin, naphthalene ring-containing epoxy resin, alicyclic epoxy resin, triglycidyl isocyanurate, aliphatic epoxy resin and the like. Of these, only one kind or two or more kinds can be selected and used. Among these, the dicyclopentadiene type epoxy resin is particularly preferable from the viewpoint of low hygroscopicity, (wet) reflow resistance and the like.

The dicyclopentadiene type epoxy resin is not particularly limited, but examples thereof include those represented by the following structural formula (2-1).

[0016]

[Chemical 6] (In the formula, n is an integer of 0 to 6.)

The epoxy resin represented by the structural formula (2-1) is, for example, EXA manufactured by Dainippon Ink and Chemicals, Inc.
In addition to 7200, it is commercially available from Nippon Kayaku Co., Ltd. The amount of the biphenyl type epoxy resin used is 20 to 100% by weight based on the total epoxy resin in the epoxy resin composition.
Is preferable. Below 20% by weight,
The effect of improving heat resistance and adhesion tends to be low.

The curing agent is not particularly limited as long as it reacts with the epoxy resin, but those having relatively little coloring are preferable for encapsulating the optical semiconductor. As a preferable example, one having two or more phenolic hydroxyl groups in one molecule, for example, phenol novolac, cresol novolac, phenol aralkyl, naphthol aralkyl, triphenylmethane type phenol, and other various polyphenol compounds are used. Alternatively, two or more kinds can be used. Among the polyphenol compounds, at least one selected from the group consisting of a phenol aralkyl resin having a skeleton represented by the following structural formula (3) and a phenol resin having a terpene skeleton represented by the following structural formula (4). It is particularly preferable to use (1) in terms of low hygroscopicity, (wet) reflow resistance and the like.

[0019]

[Chemical 7]

(In the formula, n is an integer of 1 to 5.) The ratio of the phenol resin of the above structural formula (3) and / or the above structural formula (4) to the whole curing agent used is 2
It is preferably from 0 to 100% by weight. If it is less than 20% by weight, the effect of using these phenol resins may not be sufficiently obtained.

In the epoxy resin composition, the mixing ratio of the curing agent is 0.5 equivalent to 1 equivalent of the epoxy resin.
It is preferable to set in the range of 1.5 to 1.5, and particularly preferably 0.7 to 1.0. If the equivalent of the curing agent is less than 0.5, the releasability tends to be poor, and if it exceeds 1.5, moisture absorption tends to increase and reliability tends to deteriorate. The curing accelerator is not particularly limited as long as it has an action of accelerating the reaction between the epoxy resin and the curing agent, but preferable examples include organic phosphorus compounds such as triphenylphosphine and diphenylphosphine. Imidazoles such as 2-methylimidazole, 2-phenylimidazole and 2-phenyl-4-methylimidazole; 1,8
-Diazabicyclo [5,4,0] undecene-7 ("D
BU)), diazabicyclononane (“DBN”)
(Also referred to as), tertiary amine compounds such as triethanolamine and benzyldimethylamine; organic salts such as tetraphenylphosphonium and tetraphenylborate, and the like. These may be used alone or in combination of two or more. Among these, use of an organic phosphorus compound and / or a tertiary amine compound is particularly preferable in terms of moisture resistance reliability, (wet) reflow resistance, and the like.

The mixing ratio of the curing accelerator is preferably 0.25 to 5% by weight based on the whole epoxy resin composition. If the compounding amount of the curing accelerator is less than 0.25% by weight,
Gelation time is delayed and workability tends to be significantly reduced due to insufficient curing. Conversely, if it exceeds 5% by weight, curing proceeds rapidly, resulting in large heat generation and cracks, foaming, or molding problems. This is because there is a risk that

The epoxy resin composition according to the present invention includes
A filler is blended in order to make the resin cured product less likely to crack. The filler is not particularly limited, for example, fused silica, crystalline silica,
One or more inorganic fillers such as alumina and silicon nitride can be used. Of these, fused silica is preferable in terms of fluidity, (wet) reflow resistance, and the like.

The mixing ratio of the filler is 65 to 9 of the whole composition.
It is preferably 0% by weight. In the encapsulating epoxy resin composition of the present invention, in order to sufficiently secure the rigidity at the time of molding and curing by preventing the reduction of the reaction crosslink density due to the use of the biphenyl type epoxy resin and the deactivation of the curing accelerator due to moisture. ,
An carboxylic acid anhydride having at least one cyclo ring is mixed as an additive. Specific examples thereof include, but are not particularly limited to, for example, tetrahydrophthalic acid, hexahydrophthalic acid, 4-methyltetrahydrophthalic acid, 4-methylhexahydrophthalic acid, 3-methyltetrahydrophthalic acid, succinic acid, dodecenylsuccinic acid. , Polyazelaic acid, ethylene glycol bis (trimellitate), glycerol tris (trimellitate)
And carboxylic acid anhydrides and modified products thereof. These may be used alone or in combination of two or more.

In the epoxy resin composition, the amount of the carboxylic acid anhydride compounded is 0.1 to 3.0% by weight, preferably 0.3% by weight, based on the total amount of the resin in the epoxy resin composition. ~ 1.5 wt%, more preferably 0.5-1.0
% By weight. If it is less than 0.1% by weight, the effect of addition may not be sufficiently obtained, and if it exceeds 3.0% by weight, the moisture resistance reliability may be deteriorated.

The carboxylic acid anhydride may react with water to form a carboxylic acid when it is added to the composition or when the composition is stored. It is usual to perform resin encapsulation with an epoxy resin composition using a mold, and in order to facilitate demolding, the epoxy resin composition according to the present invention may also contain a release agent. preferable. As the releasing agent, for example, natural carnauba-based, higher fatty acid, polyethylene-based wax and the like can be used, and one kind may be used or two or more kinds may be used in combination. Specifically, carnauba wax, stearic acid, stearic acid derivative, montanic acid, montanic acid derivative, carboxyl group-containing polyolefin and the like are preferably used. These may be used alone or in combination of two or more. The compounding ratio of the release agent is 0.05 to the whole composition.
It is preferably 1.5% by weight.

A colorant, a stress reducing agent, a flame retardant, a coupling agent and the like may be added to the encapsulating epoxy resin composition of the present invention in appropriate amounts, if necessary. Examples of the colorant include pigments such as carbon black and titanium oxide. Examples of the stress reducing agent include silicone gel, silicone rubber, silicone oil and the like. Examples of the flame retardant include antimony trioxide, halogen compounds, phosphorus compounds and the like. Examples of the coupling agent include silane coupling agents such as γ-glycidoxypropyltrimethoxysilane and γ-mercaptopropyltrimethoxysilane. Two or more kinds of the colorant, the stress reducing agent, the flame retardant, the coupling agent and the like may be used in combination.

The epoxy resin composition of the present invention can be produced by uniformly mixing the above-mentioned components with a mixer, a blender or the like, and then kneading them with a roll, a kneader or the like. The order of mixing the components is not particularly limited. More specifically, the epoxy resin composition of the present invention,
For example, epoxy resin, curing agent, curing accelerator, filler,
Anhydrous carboxylic acid, and further, if necessary, other mixing components are melt-mixed or melt-mixed, and then melt-kneaded with a three-roll or the like, and the kneaded product is cooled and solidified, and then pulverized,
If necessary, it can be manufactured by tableting into tablets. When the property is liquid at room temperature, it can be produced by melt mixing or melt kneading. (Sealing of semiconductor device) The epoxy resin composition thus obtained is used for transfer molding a tablet in the case of a solid using a mold, and in the case of a liquid, casting, potting, printing, etc. By casting and curing by a method, a semiconductor element mounted on a lead frame or a laminated plate of a semiconductor device such as an optical semiconductor device can be sealed.

As the above-mentioned lead frame, a lead frame made of copper or copper alloy in terms of electrical conductivity and thermal conductivity (more sophisticated elements and large-sized elements generate a larger amount of heat), and a coefficient of thermal expansion. In this regard, a lead frame made of 42 alloy alloy is generally used. Since these lead frames have low adhesiveness with bonding wires such as gold wires, the parts of the lead frame that are to be connected to the bonding wires are silver-plated or gold-plated in advance, and then connected to the bonding wires. I try to improve reliability. Copper-based lead frames are often plated with nickel, silver or gold.

[0030]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples. The present invention is not limited to the examples below. <Examples 1 to 8 and Comparative Examples 1 to 3> Epoxy resin compositions were produced with the formulations shown in Tables 1 to 3 (the unit of the formulation amount is the weight basis), and the semiconductor device was sealed. Details of each component in the table are as follows.

Epoxy resin A: Biphenyl type epoxy resin having a biphenyl skeleton of the above structural formula (1) (produced by Yuka Shell Epoxy Co., Ltd., epoxy equivalent 195, product number YX)
4000H). Epoxy resin B: dicyclopentadiene type epoxy resin represented by the structural formula (2-1) (manufactured by Dainippon Ink and Chemicals, Inc.,
Epoxy equivalent 264, product number HP7200).

Epoxy resin C: o-cresol novolac type epoxy resin (Sumitomo Chemical Co., Ltd., epoxy equivalent 1
95, product number ESCN-195XL). Epoxy resin D: Brominated epoxy resin (Sumitomo Chemical Co., Ltd., epoxy equivalent 400, product number ESB400
T). Curing agent A: Phenol aralkyl resin having the skeleton of the structural formula (3) (manufactured by Sumikin Kako Co., Ltd., hydroxyl equivalent 16)
9, product number HE100).

Curing agent B: Phenolic resin having a terpene skeleton represented by the structural formula (4) (produced by Yuka Shell Co., Ltd., hydroxyl equivalent 175, product number MP402FPY). Hardener C: Phenol novolac resin (Arakawa Chemical Co., Ltd.)
Made, hydroxyl equivalent 105, product number Tamanol). Carboxylic anhydride: 4-methylhexahydrophthalic anhydride (manufactured by Shin Nippon Rika Co., Ltd., product number RIKACID MH).

Curing accelerator A: triphenylphosphine (manufactured by Kitako Chemical Co., Ltd.). Curing accelerator B: 1,8-diazabicyclo [5,4,0]
Undecen-7 (manufactured by San-Apro Co., Ltd.). Curing accelerator C: 2-phenylimidazole (manufactured by Shikoku Chemicals Co., Ltd.). Release agent: Natural carnauba wax.

Flame retardant: Antimony trioxide (manufactured by Mitsubishi Materials Corp., product number Sb203-NT). Pigment: carbon black (manufactured by Mitsubishi Materials Corp., product number 750-B). Filler: fused silica (Tatsumori Co., Ltd.). Coupling agent: γ-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product number KBM403E).

The production conditions of the epoxy resin composition were as follows. (Production conditions for epoxy resin composition): After uniformly mixing the respective components for 30 minutes with a mixer, a blender or the like,
It was treated with a roll, a kneader or the like, and then cooled and solidified. Then, it grind | pulverized with the grinder and obtained the sealing material.

A characteristic evaluation test was conducted on each of the obtained epoxy resin compositions and molded articles thereof by the following method. (Moisture absorption rate): Diameter 50 mm, thickness 3.0 m obtained by tabletizing the material and transfer molding
The disc-shaped test piece of m was allowed to stand for 72 hours in an atmosphere of 85 ° C. and 85% RH to measure the moisture absorption rate. (Shore D hardness): 20 ± 5 seconds after the mold starts to open after the completion of molding of a disc-shaped test piece with a diameter of 50 mm and a thickness of 3.0 mm obtained by tableting the material and transfer molding It was measured with a Shore D hardness meter (manufactured by Toyo Seiki Co., Ltd.). If the measured value is 70 or less, molding trouble such as defective release occurs. (Moisture reflow resistance): Mold temperature 175 ± 5 ° C., injection time (speed) 10 seconds, pressurization (cure) time 120 seconds,
By after-curing the molded product obtained under the molding condition of the injection pressure of 60 kg / cm ² at 175 ° C. for 6 hours,
60QFP TEG (Outer diameter size: 15mm x 19mm
A thickness of 2.4 mm) for evaluation was obtained. This package was left to stand in an atmosphere of 85 ° C. and 85% RH for 72 hours to absorb moisture, then subjected to IR reflow treatment (EIAJ standard) and observed with a stereoscopic microscope for the presence or absence of cracks. (Moisture resistance reliability): The package after the above moisture reflow resistance treatment is subjected to PCT: 133 ° C./100% RH under the condition of 500.
The number of occurrences of open defects when left for a time was counted.

The results are shown in Tables 1-3.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

[Table 3]

[0042]

The encapsulating epoxy resin composition of the present invention is
Since the above-mentioned predetermined amount of the carboxylic acid anhydride having at least one cyclo ring is contained as an additive, the reduction of the reaction crosslink density and the water content can be achieved while taking advantage of the improvement of the heat resistance and the adhesiveness due to the use of the biphenyl type epoxy resin. Since it is possible to prevent deactivation of the curing accelerator due to the above, and to secure sufficient rigidity during molding and curing, it is difficult to cause molding trouble such as mold release trouble.

Since the semiconductor device of the present invention is obtained by encapsulating a semiconductor element with the encapsulating epoxy resin composition of the present invention, the semiconductor device is excellent in heat resistance, adhesiveness and the like and is resin-encapsulated. Sometimes it can be produced without causing molding troubles such as mold release troubles.

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Claims (5)

(57) [Claims] 1. A seal containing, as essential components, an epoxy resin containing at least a biphenyl type epoxy resin having a biphenyl skeleton represented by the following structural formula (1), a curing agent, a curing accelerator, and a filler. In the epoxy resin composition for stopping, the curing agent is made of a phenolic resin and contains 0.5 to 1.5 equivalents relative to 1 equivalent of the epoxy resin, and the curing accelerator is based on the entire epoxy resin composition. 0.25 to 5% by weight, and further, as an additive, an anhydride of a carboxylic acid having at least one cyclo ring is added in an amount of 0.1 to 3.
An epoxy resin composition for encapsulation, comprising 0% by weight. [Chemical 1] (In the formula, R1 to R8 are a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.) 2. The structural formula (2) below as the epoxy resin.
The epoxy resin composition for sealing according to claim 1, further comprising a dicyclopentadiene type epoxy resin having a dicyclopentadiene skeleton represented by: [Chemical 2] 3. At least one selected from the group consisting of a phenol resin having a skeleton represented by the following structural formula (3) and a phenol resin having a skeleton represented by the following structural formula (4) as the curing agent. Including at least seeds,
The epoxy resin composition for sealing according to claim 1 or 2. [Chemical 3] (In the formula, n is an integer of 1 to 5.) 4. The encapsulating material according to claim 1, wherein the curing accelerator contains at least one selected from the group consisting of organic phosphorus compounds and tertiary amine compounds. Epoxy resin composition. 5. A semiconductor device obtained by encapsulating a semiconductor element with the encapsulating epoxy resin composition according to any one of claims 1 to 4.