JP2003089719A - Epoxy resin composition for sealing semiconductor and semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition for sealing a semiconductor, having excellent storage stability, curability after absorbing moisture and moldability. SOLUTION: The epoxy resin composition comprises an epoxy resin, a curing agent, a capsule-type curing accelerator and an anhydrous alkaline earth metal compound. The capsule-type curing accelerator is obtained by covering a curing accelerator containing at least a compound represented by formula [1] [wherein, R is an electron-donative substituent selected from hydrogen atom, a 1-4C alkyl group and a 1-4C alkoxy group; and (m) is an integer of 1-5 (each of which may be same or different)], and an addition product of the compound represented by formula [1] to a quinone compound, with a covering film comprising an organic material.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin composition for semiconductor encapsulation which is excellent in storage stability and curability when absorbing moisture.

[0002]

2. Description of the Related Art Semiconductor devices such as transistors, ICs, and LSIs are mainly resin-sealed, which is advantageous in terms of mass productivity.

As a sealing resin for such a semiconductor device, a composition containing an epoxy resin, a phenol resin curing agent, and an inorganic filler is well-balanced in terms of moldability, mechanical properties, adhesiveness, etc. It is also widely used because of its high reliability.

Generally, an epoxy resin having two or more glycidyl ether groups in the molecule and a phenol resin curing agent having a hydroxyl group in the molecule are used as the base resin of the resin composition for semiconductor encapsulation. . Epoxy resin and phenol resin curing agents are used in the semiconductor device sealing process.
The glycidyl ether group reacts with the hydroxyl group in the presence of a suitable curing accelerator to give a cured product. This curing reaction rate depends on the type and amount of the curing accelerator, and these are optimized from the viewpoint of mass productivity of semiconductor devices.

Since the phenol resin curing agent has a hydroxyl group in the molecule, it easily absorbs moisture, and if it absorbs moisture, the curing reaction with the epoxy resin will be delayed, and the degree of curing of the finally obtained cured product will be low. However, there is a problem that the mass productivity of semiconductor devices decreases.

Conventionally, the mainstream of the epoxy resin composition for semiconductor encapsulation is an o-cresol novolac type epoxy resin. However, with the increase in the degree of integration of semiconductors, along with the increase in the size of silicon chips, it is required to reduce the thickness of the sealing resin layer. A biphenyl type epoxy resin has come to be used as a sealing resin which can cope with this.

As a measure for reducing the thickness of the sealing resin layer, a low thermal expansion is required to prevent cracks due to thermal stress between the silicon chip and the sealing resin layer. Therefore, a biphenyl type epoxy resin, which has a lower viscosity than the conventional o-cresol novolac type epoxy resin and in which a larger amount of a silica filler which is a low thermal expansion component can be blended, has been widely used.

However, compared with the o-cresol novolac type epoxy resin encapsulating material, the biphenyl type epoxy resin encapsulating material has a problem that the storage stability and the curability upon moisture absorption are lowered.

Since the base resin / curing agent / curing accelerator is blended in the encapsulating material, the chemical reaction gradually progresses and the fluidity decreases (storage stability decreases). Normally, the encapsulant is stored in a refrigerator as a measure for preventing fluidity deterioration, but the reaction still proceeds.

In particular, the degree of progress of the above chemical reaction is a problem because the biphenyl type epoxy resin is extremely faster than the o-cresol novolac type epoxy resin. In addition, because the cured state during semiconductor package formation is not constant, a stable quality semiconductor package cannot be obtained, and as a result,
Reliability cannot be secured.

On the other hand, if the encapsulating material for semiconductors absorbs moisture, the curing at the time of molding is impeded, which causes problems such as a decrease in mass productivity and a decrease in heat resistance of the cured product as the curing time increases. Further, in the production of a semiconductor encapsulating resin composition using a biphenyl type epoxy resin, it was necessary to take measures to keep the entire production site at low humidity and avoid the influence of moisture absorption on storage and transportation. .

As described above, the biphenyl type epoxy resin encapsulant enables the encapsulant layer to be thin, but on the other hand, it is required to improve the fluidity change (storage stability) and the curability upon moisture absorption as described above. Has been done.

As an example of using an epoxy resin encapsulating material in which a phosphorus-based curing accelerator is encapsulated, Japanese Patent Laid-Open No. 10-18
There is a 2949 publication.

This uses polyurea, which is a thermoplastic resin, as a coating film material for capsules. The encapsulation method is to create an emulsion consisting of curing accelerator / organic solvent / water,
The interfacial polymerization method is used. The capsule-type curing accelerator thus obtained has a thick coating film, and as a result, the amount of the curing accelerator contained therein is small. Therefore, since the activity of the curing accelerator becomes low, the curing reaction speed of the molded product becomes small, the molding time becomes long, and the mass productivity is lowered.

Further, it is described that the coating film of the capsule type curing accelerator disclosed in JP-A No. 11-199655 can be crosslinked and used as necessary. However, the effect of the properties with and without crosslinking is not clear.

Japanese Patent Application Laid-Open No. 58-80340 discloses a method of adding a calcium compound to an epoxy resin composition, which discloses a technique of filling calcium carbonate and magnesium hydroxide. The purpose is to improve the mechanical strength of the epoxy resin composition, and calcium carbonate cannot be expected to have an effect of promoting the curing reaction of the epoxy resin. Therefore, this technique improves mechanical strength by a composite technique in which a filler is dispersed in an epoxy resin matrix. Therefore, improvement in properties cannot be expected unless the compounding amount is considerably increased.

Further, in JP-A-58-174434, a solid base or its hydroxide is added in an amount of 0.1 to 20 in a semiconductor encapsulating epoxy resin composition comprising an epoxy resin, a curing agent and an inorganic filler. A technique of blending by weight% is disclosed.

The purpose of this technique is to prevent corrosion of the aluminum electrode pad formed on the surface of the semiconductor element. Magnesium oxide, calcium oxide,
By adding calcium hydroxide or aluminum oxide, the water that has penetrated into the semiconductor encapsulating layer becomes neutral or alkaline, thereby preventing corrosion of aluminum.

When the o-cresol novolac type epoxy resin is used, the corrosion of the aluminum pad due to the hydrolyzable chlorine ions contained in the resin has become a problem, but recently, the epoxy resin itself is highly susceptible to corrosion. Since purification is progressing, the concentration of hydrolyzable chlorine ions is extremely low, and the corrosion of the aluminum pad as described above is reduced.

The semiconductor encapsulant using the biphenyl type epoxy resin contains hydrolyzable chlorine ions because it is highly filled with silica as a filler as compared with the o-cresol novolac type epoxy resin encapsulant. Low resin content,
In addition, since the adhesiveness with the insert member is also good, there are very few cases where corrosion of the aluminum pad is a problem.

[0021]

The biphenyl type epoxy resin encapsulant can make the encapsulating layer thin, but the chemical reaction proceeds even at a relatively low temperature of room temperature or lower, and the fluidity decreases. Moreover, the encapsulant absorbs moisture just by leaving it at room temperature / humidity to cause curing inhibition.

In view of such a situation, an object of the present invention is to provide an epoxy resin composition for semiconductor encapsulation, which has improved fluidity and curability upon moisture absorption.

[0023]

[Means for Solving the Problems] The present inventors have examined a curing agent, a curing accelerator, various additives and the like which are considered to affect the above properties. As a result, it has been found that, in order to prevent fluidity deterioration, the effect is exhibited by coating a curing accelerator with an organic substance and encapsulating it so as to minimize chemical contact with a phenol resin curing agent or an epoxy resin.

Further, it has been found that the addition of a small amount of an alkaline earth metal compound improves the curability when absorbing moisture. Alkaline earth metal compounds do not have water of crystallization, and react with the water taken into the resin to become a stable metal hydrate, reducing the water content in the resin and reducing the inhibition of the curing reaction. I found that. The gist of the present invention is as follows.

An epoxy resin composition for semiconductor encapsulation is obtained by adding a capsule type curing accelerator and an alkaline earth metal compound having no water of crystallization to an epoxy resin. By using such a composition, the fluidity and the curability upon absorption of moisture can be improved at the same time.

In the epoxy resin composition for semiconductor encapsulation of the present invention, known epoxy resins usually used for semiconductor encapsulation can be used. For example, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol or cresol-based multifunctional epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin. Examples thereof include resins, dicyclopentadiene type epoxy resins, stilbene type epoxy resins, sulfur atom-containing epoxy resins, brominated epoxy resins and the like. In particular, biphenyl type epoxy resin and naphthalene type epoxy resin are preferable.

As the biphenyl type epoxy resin, 4,
4'-bis (2,3-epoxypropoxy) biphenyl,
4,4'-bis (2,3-epoxypropoxy) -3,3 ',
An epoxy resin containing a bifunctional epoxy resin having a biphenyl skeleton such as 5,5′-tetramethylbiphenyl as a main component is preferable, and as the naphthalene type epoxy resin,
An epoxy resin containing a bifunctional epoxy resin having a naphthalene ring as a main component is preferable.

In the epoxy resin composition for encapsulating a semiconductor of the present invention, the curing agent is not particularly limited, and a phenol compound having one or more phenolic hydroxyl groups per molecule, particularly two phenolic hydroxyl groups is contained. Compounds are preferred.

Examples thereof include phenol novolac resin, xylylene type phenol resin, bisphenol resin, o-cresol novolac resin and polyparavinylphenol resin. The mixing ratio of the epoxy resin and the phenol resin curing agent can be such that the hydroxyl group equivalent in the phenol resin curing agent is 0.5 to 2.0 with respect to 1 equivalent of the epoxy group in the epoxy resin.

In the epoxy resin composition for semiconductor encapsulation of the present invention, the capsule type curing accelerator is not particularly limited, and it means that the coating film is formed on the surface of the curing accelerator.

The encapsulated curing accelerator can be obtained, for example, by mixing and stirring the curing accelerator and the coating film material.

The capsule type curing accelerator has the general formula [1]

[0033]

[Chemical 2] [In the formula, R is a hydrogen atom, an electron-donating substituent selected from an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and m is an integer of 1 to 5 (may be the same or different from each other. )] Or a curing accelerator containing at least one addition reaction product of a compound represented by the general formula [1] and a quinone compound is coated with an organic coating film material. Those containing a mold hardening accelerator are preferable.

Specific examples of the compound represented by the general formula [1] include triphenylphosphine, tris (methylphenyl) phosphine, tris (dimethylphenyl) phosphine, tris (trimethylphenyl) phosphine, tris (ethylphenyl) phosphine. , Tris (propylphenyl) phosphine, tris (alkylphenyl) phosphine such as tris (butylphenyl) phosphine, tris (methoxyphenyl) phosphine, tris (dimethoxyphenyl) phosphine, tris (ethoxyphenyl) phosphine, tris (methoxyethoxyphenyl)
Examples include tris (alkoxyphenyl) phosphine such as phosphine and tris (butoxyphenyl) phosphine, and tris (alkyl / alkoxyphenyl) phosphine such as tris (methylmethoxyphenyl) phosphine.

Further, the compound represented by the general formula [1] can be used by addition reaction with a quinone compound having one or more conjugated double bonds in one molecule. Examples of quinone compounds include p-benzoquinone and 1,4-naphthoquinone.

The coating film material for the capsule type curing accelerator used in the epoxy resin composition for semiconductor encapsulation of the present invention is not particularly limited, but may be selected from organic materials such as epoxy resin, phenol resin, polyimide resin, acrylic resin and the like. The following are preferable, and those containing an epoxy resin, a phenol resin curing agent, and a curing accelerator as essential components are more preferable. As these three components, known ones usually used for semiconductor encapsulation can be used.

For example, as the epoxy resin used for the coating film material, phenol novolac type epoxy resin, cresol novolac type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin. , Naphthalene type epoxy resin, dicyclopentadiene type epoxy resin, stilbene type epoxy resin, sulfur-containing epoxy resin, brominated epoxy resin and the like.

Examples of the phenol resin curing agent used for the coating film material include phenol novolac resin, xylylene type phenol resin, bisphenol resin, o-cresol novolac resin and polyparavinylphenol resin.

The curing accelerator used in the coating film material is, for example, a compound represented by the above general formula [1],
A phosphorus compound such as an addition reaction product of the compound with a quinone compound, 1,8-diazabicyclo (5,4,0) undecene, 1,
There are amine compounds such as 5-diazabicyclo (4,3,0) 5-nonene, triethanolamine, and 2-dimethylamino-2-hydroxypropane. The components used for the above-mentioned coating film material can also be used by being mixed by heating, melting, and pulverizing after cooling.

The component amount of the curing accelerator contained in the capsule type curing accelerator is preferably 30 to 95% by weight,
50 to 90% by weight is more preferable. If it is less than 30% by weight, the catalytic activity of the curing accelerator is too low, or the content ratio of the coating film material is too high, so that it becomes difficult to obtain desired molding material characteristics. On the other hand, if it exceeds 95% by weight, the number of reaction starting points between the curing accelerator containing phosphorus and the reactive resin component increases, so that the chemical reaction rate during storage and during molding increases, and the effect of encapsulation becomes difficult to be exhibited.

On the surface of the curing accelerator in the capsule type curing accelerator, a coating film material may be at least partially or entirely coated, and may be crosslinked if necessary. The coating film material after coating preferably has a softening point or glass transition temperature of 80 to 200 ° C.

In general, the encapsulating material is prepared by kneading the components of the encapsulating composition with a kneader heated to 60 to 120 ° C. for a predetermined time. The softening point or glass transition temperature of the coating material is 80 ° C
When it is less than 1, the coating film is likely to be damaged by friction with the filler during kneading of the sealing composition with a kneader. Therefore, the effect of coating with the coating film material is reduced, and there is a possibility that the chemical reaction proceeds during storage and the fluidity of the sealing material is reduced.

On the other hand, if the temperature exceeds 200 ° C., the heat resistance of the coating film material is too high and softening does not occur under the usual semiconductor package molding conditions, so that the curing accelerator does not easily come out of the capsule. Since the amount of the curing accelerator that should be involved in the reaction is apparently insufficient, the curing reaction rate may decrease, continuous molding of the semiconductor package may not be possible, and a stable quality product may not be obtained.

On the other hand, an alkaline earth metal compound is suitable for improving the curability of the epoxy resin encapsulant when absorbing moisture. In the present invention, it is necessary to use an alkaline earth metal compound having no water of crystallization. As the alkaline earth metal compound, an oxide of an alkaline earth metal is preferable,
Specific examples include calcium oxide, magnesium oxide, barium oxide, and strontium oxide. These produce hydroxides by reacting with water and are stably present in the cured product. In particular, calcium oxide is excellent in terms of moisture absorption and stability in a cured product.

The alkaline earth metal compound such as calcium oxide used in the present invention is preferably a powder, and particularly preferably has an average particle size of about 0.1 to 100 μm. If the average particle size is less than 0.1 μm, the thixotropy of the epoxy resin composition will be high and the viscosity will increase, making molding difficult.

If the average particle size exceeds 100 μm, it becomes impossible to fill the material in the narrow portion of the material flow path in the mold, or the resin component and the filler are easily separated, so that a stable molded product can be obtained. I will not be able to. The method of pulverization is not particularly limited, and it can be performed using a conventional method.

The amount of the alkaline earth metal compound compounded is 0.1 with respect to the curing agent in the epoxy resin composition for semiconductor encapsulation.
5 to 50% by weight is preferable. If the addition amount is less than 0.5% by weight, the effect of reducing the moisture absorbed by the epoxy resin is small. On the other hand, if it exceeds 50% by weight, the viscosity of the epoxy resin encapsulant increases, so that the fluidity decreases and it becomes impossible to obtain a molded product of stable quality.

In the epoxy resin composition for semiconductor encapsulation of the present invention, the addition of an alkaline earth metal compound is intended to improve the curability upon absorption of moisture.

In the epoxy resin composition for semiconductor encapsulation of the present invention, the epoxy resin is not particularly limited,
As described above, known ones usually used for semiconductor encapsulation can be used, but the greatest effect appears when an alkaline earth metal compound is added to a biphenyl type epoxy resin or a naphthalene type epoxy resin.

If necessary, the epoxy resin composition for semiconductor encapsulation of the present invention has toughness and low elastic modulus, and
A filler, a softening agent, a coupling agent, a lubricant, a coloring agent and the like can be added for the purpose of improving properties such as adhesiveness and releasability.

Known inorganic and organic substances can be used as the filler. Among them, particularly fine particles of fused silica, crystalline silica, alumina, calcium carbonate, calcium silicate, talc, clay, mica and the like have moldability and thermal expansion coefficient,
It is suitable for balancing electrical characteristics and mechanical strength.
The average particle size of the filler is preferably 0.1 to 50 μm,
5 to 30 μm is particularly suitable. Average particle size 0.1 μm
If it is less than 3, the thixotropy of the epoxy resin composition will be high, the viscosity will increase, and the moldability will be difficult. The average particle size is 5
If it exceeds 0 μm, the material cannot be filled into the isthmus of the material flow path in the mold, or the resin component and the filler are easily separated from each other, which makes it difficult to obtain a stable molded product.

Further, a silicone-based softening agent, a silane-based coupling agent, a higher fatty acid-based lubricant, a carbon colorant,
Known materials can be used as the adhesion-imparting agent, the flame retardant aid, antimony trioxide, and the like.

These above components are blended, mixed, pulverized, and further granulated as required to obtain the epoxy resin composition for semiconductor encapsulation of the present invention. The kneading is generally performed with a hot roll or an extruder.

The semiconductor device of the present invention is obtained by sealing with the epoxy resin composition obtained as described above. The production method can be performed by a conventional method.

Usually, low pressure transfer molding is used, but compression molding, casting or the like can be used if necessary. Further, in order to improve the reliability of the semiconductor device, it is desirable to perform heat treatment at a temperature of 150 ° C. or higher for a desired time after molding with the epoxy resin composition in order to obtain sufficient curing.

In the epoxy resin composition obtained by the conventional method, since all of the curing accelerators are in contact with the curing agent and the epoxy resin which are the reactive components, the epoxy resin can be formed by the progress of the curing reaction. Since the polymer has a high molecular weight, the viscosity at the time of molding rises and desired fluidity cannot be obtained, and so-called storage stability lowers.

The epoxy resin composition for semiconductor encapsulation of the present invention exhibits excellent storage stability and curability upon absorption of moisture, can be stably stored for a long period of time, and is not particularly required to select a use environment, and its usability is greatly improved. improves. Therefore, the epoxy resin composition for semiconductor encapsulation changes its characteristics during storage or use and is out of the range of the user's specifications, which is unusable.

In addition, when the semiconductor is sealed, an excellent semiconductor device with stable quality can be formed, which is also excellent in mass productivity.

By using the capsule type curing accelerator of the present invention, the epoxy resin composition for encapsulating a semiconductor (encapsulating material) suppresses a chemical reaction that proceeds during storage and improves storage stability. This is because the surface of the curing accelerator is at least partly covered with the encapsulating coating film, so that there are few contact points with the curing agent and the epoxy resin which are the reaction components. Therefore, the chemical reaction that progresses during storage of the epoxy resin composition for semiconductor encapsulation is suppressed, and the change in fluidity is reduced.

The coating film forming the capsule-type curing accelerator of the present invention has a softening point or glass transition temperature of 80 to 2
It is 00 ° C. The molding temperature of a semiconductor device is generally 150 to
Since the temperature is 200 ° C., the capsule coating film of the present invention is softened or dissolved at this temperature, and the curing accelerator exits from the capsule coating film. Therefore, the curing reaction action of the curing accelerator in the molding temperature range is carried out as usual to obtain a desired molded product.

The effect of the addition of the alkaline earth metal compound in the present invention is to reduce the inhibition of curing by the trace amount of water in the epoxy resin composition in the curing reaction of the epoxy resin composition for semiconductor encapsulation. As is well known, alkaline earth metal compounds react with water to form hydroxides.
Similar changes occur in the epoxy resin composition for semiconductor encapsulation of the present invention, and the effect is exhibited during the curing reaction of the epoxy resin composition.

A trace amount of water in the epoxy resin composition for semiconductor encapsulation of the present invention remains in the composition because it is pressurized even when heated to a temperature of 100 ° C. or higher during molding, which is a factor causing curing inhibition. Becomes The alkaline earth metal compound is
Even during this curing, moisture is absorbed by changing from oxide to hydroxide, and as a result, there is an effect that the influence of moisture during the curing reaction does not occur.

Further, since the alkaline earth metal compound itself does not participate in the curing reaction itself of the epoxy resin, it does not affect the curing reaction in the room temperature dry state. Therefore, the epoxy resin composition for semiconductor encapsulation of the present invention can simultaneously improve the storage stability of the encapsulant and the curability in a hygroscopic state.

Capsule type curing accelerator has a form in which a coating film for capsules, which is an organic substance, is coated on the surface of the curing agent which is a core, or at least a part of the surface of the core.

[0065]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be specifically described based on Examples.

Example 1 A capsule-type curing accelerator was produced as follows. o-cresol novolac type epoxy resin (Sumitomo Chemical, epoxy equivalent: 195 g / e
q) 100 g, phenol novolac resin (Meiwa Kasei,
54 g of hydroxyl equivalent: 106 g / eq) was put into a glass beaker, heated and melted at 80 ° C., mixed, cooled, and finely pulverized to obtain a coating film material for capsules.

Next, 4 g of the coating film material for capsules and 16 g of tetra (4-methylphenyl) phosphonium tetraphenylborate were put into a surface reforming device (Nara Machinery Co., Ltd., Hybridizer, NHS-0 type), and Capsule type tetra (4-methylphenyl) phosphonium tetraphenylborate (hereinafter abbreviated as MC-1) was produced under the conditions.

The manufacturing conditions were such that the rotation time was 4 minutes and the rotor rotation speed was 14,000 rpm in air. MC-1 obtained
Is a curing accelerator content: 80% by weight, particle size: 1 to 20 μ
m, softening point of coating film material: 80 ° C.

Next, using o-cresol novolac type epoxy resin (Sumitomo Chemical Co., Ltd .: ESCN-190), M
An epoxy resin composition for semiconductor encapsulation having a composition shown in Table 1 was prepared using C-1. The encapsulating material was prepared by kneading with a twin-screw kneading roll at 70 ° C. for 10 minutes, taking out, cooling, and crushing into about 2 mm square.

[0070]

[Table 1]

[Table 2] The flow length residual rate (storage stability) of the epoxy resin composition for semiconductor encapsulation was evaluated by storing the encapsulant in a silica gel desiccator (humidity: 20% RH or less) at 25 ° C. for a predetermined time,
The flow length at that time was measured and determined by the following. [Formula 1] Flow length residual rate (%) = (flow length after storage in a desiccator /
Flow length before storage in a desiccator) × 100 The residual moisture hardness of the epoxy resin composition for semiconductor encapsulation is 25 ° C. and 50% RH. After encapsulating the encapsulating material for a predetermined time, press the encapsulating material. Immediately after molding, the molded product was measured with a Barcol hardness meter, and the hardness change was determined.

The press molding conditions were temperature: 180 ° C., molding time: 90 seconds, pressure: 7 MPa, and the results are shown in Table 2. The hardness residual rate was determined as follows. [Numerical formula 2] Hardness residual rate (%) = (Hardness at heat after storage in desiccator /
Hardness at the time of heat before storage in a desiccator) × 100 Even if the sealing material is stored at 25 ° C. and 20% RH or less for 3 days, the residual ratio of the flow length is 90%. Also, the sealing material is 25
The hardness residual rate is 90 even when stored at 50 ℃ and 50% RH for 3 days.
Held more than%. The flow length residual rate of Comparative Examples 1 and 2 in which the curing accelerator is not encapsulated is 3
It dropped to 82-83% in a day.

Example 2 Biphenyl Epoxy Resin (Japan Epoxy Resin: Epicot YX-4000
An epoxy resin composition for semiconductor encapsulation was prepared with the composition shown in Table 1 using H and an epoxy equivalent of 190 g / eq) and the same capsule-type curing accelerator MC-1 as used in Example 1. The production method was such that the mixture was kneaded with a biaxial kneading roll at 80 ° C. for 10 minutes, taken out, cooled, and pulverized into about 2 mm square to obtain a sealing material.

The flow length residual rate evaluation method, hardness residual rate evaluation method, roll kneading conditions and press molding conditions of the epoxy resin composition for semiconductor encapsulation are the same as in Example 1.

Also in the epoxy resin composition for semiconductor encapsulation using the biphenyl type epoxy resin highly filled with the filler, the residual ratio of flow length and the residual ratio of hardness can be remarkably improved. The cured product of the obtained sealing material has a thermal expansion coefficient of 10 ppm.
/ K, 85 ° C., 85% RH, moisture absorption was 0.32% when absorbed for 1 week, and all the properties were excellent.

Example 3 A capsule type curing accelerator is
It was produced as follows. Polyetherimide (Sumitomo Bakelite, FS-1200, glass transition temperature 190
What was finely pulverized to 200 μm was used as a coating film material for capsules.

Then, 4 g of the above-mentioned coating film material for capsules,
16 g of an addition reaction product of triphenylphosphine and p-benzoquinone was put into a surface reforming device (Nara Machinery Co., Ltd., Hybridizer, NHS-0 type), and capsule type triphenylphosphine / p-benzoquinone (hereinafter , MC-2).

The manufacturing conditions are that the rotation time is 4 minutes and the stator rotation speed is 14,000 rpm in air. MC-2 obtained
Is a curing accelerator content: 80% by weight, particle size: 1 to 20 μ
m, glass transition temperature of coating film material: 160 ° C.

Next, using MC-2, an epoxy resin composition for semiconductor encapsulation having the composition shown in Table 1 was prepared. The production method was such that the mixture was kneaded with a biaxial kneading roll at 80 ° C. for 10 minutes, taken out, cooled, and pulverized into about 2 mm square to obtain a sealing material.

The flow length residual rate evaluation method, hardness residual rate evaluation method, roll kneading condition and press molding condition of the epoxy resin composition for semiconductor encapsulation were the same as in Example 1 except that the molding temperature was 200 ° C.

By using the compound represented by the above formula [1] as the catalyst in the capsule, it was possible to achieve not only storage stability but also fast curing property. As a result of measuring the reaction curability of the epoxy resin composition for semiconductor encapsulation at 200 ° C. with a curast meter (Imanaka Machine Industry, JSR type), the 90% curing degree is 65 seconds.

Example 4 A capsule-type curing accelerator was produced as follows. Acrylic resin powder (Soken Chemical, product name: MP-1451, average particle size:
0.15 μm) was used as is.

Next, 4 g of the coating material for capsules, the addition reaction product 1 of triphenylphosphine and p-benzoquinone 1
6 g was put into a surface reforming device (Nara Machinery Co., Ltd., Hybridizer, NHS-0 type), and capsule-type triphenylphosphine p-benzoquinone (hereinafter, M
C-3) was produced. The manufacturing conditions are that the rotation time is 4 minutes and the stator rotation speed is 14,000 rpm in air. The obtained MC-3 has a curing accelerator content of 80% by weight, a particle size of 1 to 20 μm, and a softening point of the coating film material: 100 ° C.

Next, MC-3 and naphthalene type epoxy resin (Dainippon Ink and Chemicals, Epicron EXA-47
00: Epoxy equivalent 163 g / eq) and the like in Table 1.
An epoxy resin composition for semiconductor encapsulation was prepared with the composition described. The production method was such that the mixture was kneaded with a biaxial kneading roll at 80 ° C. for 10 minutes, taken out, cooled, and pulverized into about 2 mm square to obtain a sealing material.

The flow length residual rate evaluation method, hardness residual rate evaluation method, roll kneading conditions and press molding conditions of the epoxy resin composition for semiconductor encapsulation are the same as in Example 1.

Example 5 A capsule-type curing accelerator was produced as follows. o-cresol novolac type epoxy resin (Sumitomo Chemical, epoxy equivalent: 195 g / e
q) 100 g, phenol novolac resin (Meiwa Kasei,
54 g of hydroxyl equivalent: 106 g / eq) was put into a glass beaker, heated and melted at 80 ° C., mixed, cooled, and finely pulverized to obtain a coating film material for capsules.

Next, 4 g of the coating material for capsules and 16 g of triphenylphosphine were put into a surface reforming apparatus (Nara Machinery Co., Ltd., Hybridizer, NHS-0 type), and the capsule type triphenylphosphine (hereinafter, MC
(Abbreviated as -4) was produced. The manufacturing conditions are that the rotation time is 4 minutes and the stator rotation speed is 14,000 rpm in air. The obtained MC-4 had a curing accelerator content of 80% by weight and a particle size of:
1 to 20 μm, softening point of coating film material: 80 ° C.

Next, using MC-4, an epoxy resin composition for semiconductor encapsulation having the composition shown in Table 1 was prepared. The encapsulating material was prepared by kneading with a twin-screw kneading roll at 70 ° C. for 10 minutes, taking out, cooling, and crushing into about 2 mm square.

The flow length residual rate evaluation method, hardness residual rate evaluation method, roll kneading conditions and press molding conditions of the epoxy resin composition for semiconductor encapsulation are the same as in Example 1.

It was found that the addition of calcium oxide as the alkaline earth metal compound has a remarkable effect on the improvement of the hardness residual rate.

Example 6 A capsule-type curing accelerator was prepared as follows. o-cresol novolac type epoxy resin (Sumitomo Chemical, epoxy equivalent: 195 g / e
q) 100 g, phenol novolac resin (Meiwa Kasei,
Hydroxyl equivalent: 106 g / eq) 54 g, addition reaction product 4 g of tris (methylphenyl) phosphine and p-benzoquinone were placed in a glass beaker and heated and melted at 80 ° C.,
What was mixed, cooled and finely pulverized was used as a coating film material for capsules.

Next, 4 g of the coating material for capsules and 16 g of the addition reaction product of tris (methylphenyl) phosphine and p-benzoquinone were put into a surface reforming device (Nara Machinery Co., Ltd., Hybridizer, NHS-0 type). , Capsule type tris (methylphenyl) phosphine / p-
Benzoquinone (hereinafter abbreviated as MC-5) was produced. Manufacturing conditions are air, rotation time 4 minutes, stator rotation speed 14,
000 rpm.

Next, the obtained MC-5 was heat-crosslinked for 2 hours in a constant temperature bath at 190 ° C. MC-5 has a curing accelerator content of 80% by weight, a particle size of 1 to 25 μm, and a softening point of the coating film material: 160 ° C.

Next, using MC-5, an epoxy resin composition for semiconductor encapsulation having the composition shown in Table 1 was prepared. The production method was such that the mixture was kneaded with a biaxial kneading roll at 80 ° C. for 10 minutes, taken out, cooled, and pulverized into about 2 mm square to obtain a sealing material.

The flow length residual rate evaluation method, hardness residual rate evaluation method, roll kneading conditions and press molding conditions of the epoxy resin composition for semiconductor encapsulation are the same as in Example 1.

By adding the curing accelerator to the coating film material composition of the encapsulation curing accelerator, more remarkable potential is exhibited and the flow length residual rate is further improved. It is considered that this is because the coating film material exhibits cross-linking toughness and prevents damage to the film material during roll kneading.

Example 7 A capsule-type curing accelerator was prepared as follows. o-cresol novolac type epoxy resin (Sumitomo Chemical, epoxy equivalent: 195 g / e
q) 100 g, phenol novolac resin (Meiwa Kasei,
Hydroxyl equivalent: 106 g / eq) (54 g) was placed in a glass beaker, and 3.5 g of an addition reaction product of triphenylphosphine and p-benzoquinone was heated and melted at 80 ° C., mixed, cooled, and finely pulverized to obtain a capsule capsule. It was used as a covering material.

Then, 4 g of the coating material for capsules, the addition reaction product 1 of triphenylphosphine and p-benzoquinone 1
6 g was put into a surface reforming apparatus (Nara Machinery Co., Ltd., Hybridizer, NHS-0 type), and capsule-type triphenylphosphine (hereinafter abbreviated as MC-6) was produced under the following conditions. The manufacturing conditions are that the rotation time is 4 minutes and the stator rotation speed is 14,000 rpm in air. The obtained MC-6 was 1
It was heat-crosslinked for 2 hours in a thermostat at 20 ° C. MC-6 has a curing accelerator content of 80% by weight, a particle size of 1 to 20 μm, and a softening point of the coating film material: 120 ° C.

Next, using MC-6, an epoxy resin composition for semiconductor encapsulation having the composition shown in Table 1 was prepared. The production method was such that the mixture was kneaded with a biaxial kneading roll at 80 ° C. for 10 minutes, taken out, cooled, and pulverized into about 2 mm square to obtain a sealing material.

The flow length residual rate evaluation method, hardness residual rate evaluation method, roll kneading conditions and press molding conditions of the epoxy resin composition for semiconductor encapsulation are the same as in Example 1.

The system in which the softening point was adjusted to 120 ° C. and calcium oxide was added for the purpose of imparting toughness to the coating film material of the encapsulation hardening accelerator, both the flow length residual rate and the hardness residual rate deteriorated. Holds 90% after a week.

[Embodiment 8] FIG. 1 shows a resin-type semiconductor device encapsulated with the encapsulant of Embodiment 7. Semiconductor element 1
Is a semiconductor device that is mounted on the die pad 2 via an adhesive layer 4, and the external output pad 6 of the semiconductor element 1 and the external lead 3 are electrically connected by a conductive wire 5. It was obtained by molding with a transfer press except for the parts. Molding conditions are mold temperature 180 ℃, molding pressure 7MP
a, molding time is 90 seconds.

The obtained semiconductor device operated normally without corrosion of the wiring even after being left in a pressure cooker kettle at 121 ° C. and 2 atm for 500 hours.

[Embodiment 9] FIG. 2 shows a resin-type semiconductor device encapsulated with the encapsulant of Embodiment 6. In the semiconductor element 1 having an electric circuit, a part of the surface having the circuit layer and the lead 3 are connected and held by the connection layer 8. The external connection pad 6 on the surface having the circuit layer is electrically connected to the external lead 3, and transfer press molding is performed except for a part of the external lead 3. Molding conditions are mold temperature 18
0 ° C., molding pressure 7 MPa, molding time 90 seconds.

The obtained semiconductor device operated normally without being broken by corrosion even after being left in a pressure cooker pot at 121 ° C. and 2 atm for 500 hours.

Comparative Example 1 An epoxy resin composition for encapsulation was prepared with the composition shown in Table 3 based on biphenyl type epoxy resin and unencapsulated triphenylphosphine.

As the epoxy resin, biphenyl type epoxy resin (Japan epoxy resin, Epicote YX-4000H: epoxy equivalent 190 g / eq), brominated epoxy resin (Sumitomo Chemical, ESB-400T: epoxy equivalent 375 g / eq) are used. ) And a xylylene type epoxy resin (Mitsui Chemicals, Milex XL-225-3L: Epoxy equivalent 171 g / eq), and roll kneading temperature: 8
0 ° C, kneading time: 10 minutes, press molding conditions are temperature: 18
Molding was performed at 0 ° C., molding time: 90 seconds, pressure: 70 MPa.

The flow length residual rate evaluation method, hardness residual rate evaluation method, roll kneading condition and press molding condition of the epoxy resin composition for encapsulation are the same as in Example 1. The results are shown in Table 4.

[0108]

[Table 3]

[Table 4] [Comparative Example 2] As in Comparative Example 1, a biphenyl-type epoxy resin and unencapsulated triphenylphosphine were used, and an epoxy resin composition for encapsulation was prepared with the composition shown in Table 3 based on the addition of calcium oxide. . The same epoxy resin as in Comparative Example 1 was used. Flow length residual rate evaluation method of epoxy resin composition for semiconductor encapsulation,
The hardness residual rate evaluation method, roll kneading conditions, and press molding conditions are the same as in Example 1. The results are shown in Table 4.

[Comparative Example 3] An encapsulant was prepared with the composition shown in Table 3 based on the biphenyl type epoxy resin and the capsule type curing accelerator MC-6 used in Example 7. The same epoxy resin as in Comparative Example 1 was used. Flow length residual rate evaluation method of epoxy resin composition for semiconductor encapsulation,
The hardness residual rate evaluation method, roll kneading conditions and press molding conditions are the same as in Example 1. The results are shown in Table 4.

[0110]

The epoxy resin composition for semiconductor encapsulation of the present invention uses a capsule type curing accelerator together with an alkaline earth metal compound (eg, calcium oxide) having no water of crystallization as a curing aid. As a result, both excellent storage stability and curability upon absorption of moisture can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a resin-sealed semiconductor device of Example 8.

FIG. 2 is a schematic cross-sectional view of a resin-encapsulated semiconductor device of Example 9.

[Explanation of symbols]

1 ... Semiconductor element, 2 ... Die pad, 3 ... External lead, 4
... Adhesive layer, 5 ... Conductive wire, 6 ... External output pad,
7 ... Epoxy resin composition for sealing (sealing material), 8 ... Connection layer.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akira Nagai             7-1-1, Omika-cho, Hitachi-shi, Ibaraki Prefecture             Inside the Hitachi Research Laboratory, Hitachi Ltd. (72) Inventor Toshiaki Ishii             7-1-1, Omika-cho, Hitachi-shi, Ibaraki Prefecture             Inside the Hitachi Research Laboratory, Hitachi Ltd. (72) Inventor Takao Miwa             7-1-1, Omika-cho, Hitachi-shi, Ibaraki Prefecture             Inside the Hitachi Research Laboratory, Hitachi Ltd. (72) Inventor Shinsuke Hagiwara             Hitachi Chemical Co., Ltd. 1772, Kagoku, Yuki City, Ibaraki Prefecture             Shimodate Office of Industry Co., Ltd. F-term (reference) 4J002 CD031 CD041 CD051 CD061                       CD111 CD121 CD171 CD181                       DE066 DE086 FD206 GQ05                 4J036 AA01 AD07 AD08 AD21 AF06                       AF07 AF08 AJ08 CB07 CC01                       DA04 DD07 HA07 JA07                 4M109 AA01 CA21 EA03 EB04 EB12

Claims (13)

[Claims] 1. An epoxy resin composition for semiconductor encapsulation containing an epoxy resin, a curing agent, a capsule-type curing accelerator, and an alkaline earth metal compound, wherein the alkaline earth metal compound does not have water of crystallization. An epoxy resin composition for semiconductor encapsulation, comprising: 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the alkaline earth metal compound is calcium oxide. 3. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the epoxy resin is a biphenyl type epoxy resin or a naphthalene type epoxy resin. 4. The capsule-type curing accelerator has the general formula [1]: [In the formula, R is a hydrogen atom, an electron-donating substituent selected from an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, and m is an integer of 1 to 5 (may be the same or different from each other. )] Or a curing accelerator containing at least one addition reaction product of a compound represented by the general formula [1] and a quinone compound is coated with an organic coating film material. The epoxy resin composition for semiconductor encapsulation according to claim 1, 2 or 3, further comprising a mold curing accelerator. 5. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the coating film material of the capsule-type curing accelerator has a softening point or a glass transition temperature of 80 to 200 ° C. 6. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the coating film material of the capsule type curing accelerator contains an epoxy resin, a phenol resin curing agent and a curing accelerator. 7. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the content of the curing accelerator in the capsule type curing accelerator is 3 to 95% by weight. 8. A semiconductor element having an electric circuit formed thereon, an external terminal for electrically connecting to a mounting board, an adhesive layer for fixing the semiconductor element to the external terminal, and an electrical connection between the semiconductor element and the external terminal. In the semiconductor device comprising an electric conductor for, a resin composition encapsulant for encapsulating these necessary parts, the resin composition encapsulant is an epoxy resin, a curing agent,
A semiconductor device, which is an epoxy resin composition containing a capsule-type curing accelerator and an alkaline earth metal compound, wherein the alkaline earth metal compound does not have water of crystallization. 9. The semiconductor device according to claim 8, wherein the alkaline earth metal compound is calcium oxide. 10. The semiconductor device according to claim 8, wherein the epoxy resin is a biphenyl type epoxy resin or a bifunctional epoxy resin having a naphthalene ring. 11. The hardening accelerator in the capsule-type hardening accelerator is represented by the general formula [1] [wherein R is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms]. An electron-donating substituent selected from m is an integer of 1 to 5 (may be the same or different from each other)], or addition of a compound represented by the general formula [1] and a quinone compound The semiconductor device according to claim 8, 9 or 10, further comprising a capsule-type curing accelerator in which the curing accelerator containing at least one of the reactants is coated with a coating film material made of an organic material. 12. The semiconductor device according to claim 8, wherein the coating film material of the capsule type curing accelerator has a softening point or a glass transition temperature of 80 to 200 ° C. 13. The semiconductor device according to claim 8, wherein the coating film material of the capsule type curing accelerator contains an epoxy resin, a phenol resin curing agent, and a curing accelerator.