JPH09208807A - Epoxy resin composition for sealing material and semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy ewsin compsn. for a sealing material excellent in adhesion to a lead frame and mold release by compounding an epoxy resin with a hardner, an inorg. filler, a specific mold release, and an organosilazane. SOLUTION: This compsn. in an amt. of 100 pts.wt. comprises an epoxy resin, a hardner, 60-95 pts.wt. inorg. filler, 0.05-0.5 pt.wt. compd. having a linkage represented by -OCO-NH-COO-as a mold release, and 0.2-1.0 pt.wt. organosilazane represented by the formula (wherein R<1> to R<8> are each H or a 1-3C hydrocarbon group; and (n) is 0 or a positive integer) having 1-4 silicon atoms as a coupling agent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and an epoxy resin composition for an encapsulant used for encapsulating the same.

[0002]

2. Description of the Related Art As a method for sealing electronic components such as semiconductor devices, a method using ceramic or thermosetting resin has been conventionally used. Among them, encapsulation with an epoxy resin composition is more preferable than the balance between economic efficiency and performance,
Widely used. A semiconductor device sealed with this epoxy resin composition has, for example, a semiconductor chip mounted on a lead frame metal, and the semiconductor chip and the lead frame are electrically connected using a bonding wire or the like. And part of the lead frame,
It is formed by sealing with an epoxy resin composition for a sealing material (hereinafter referred to as a sealing resin).

Transfer molding is generally used as a method of sealing with a sealing resin. When sealing is performed by this transfer molding, a cured product of the sealing resin (hereinafter referred to as a resin cured product) and the mold may adhere to each other and become difficult to separate from each other. For the purpose of improvement, a method of incorporating a release agent into the sealing resin to improve the releasability has been studied. As this release agent, natural carnauba, higher fatty acids such as montanic acid or esters thereof are generally used.

Further, when the resin cured product of the electronic component absorbs moisture, the absorbed moisture rapidly expands due to thermal shock of soldering when mounting the electronic component, and a crack is generated inside the cured resin product, which is reliable. There was a case where the problem that the property deteriorates occurred. Therefore, as an improvement of moisture absorption solder cracking property, a method of reducing the moisture absorption of the resin cured product by reducing the proportion of the epoxy resin, which is a component that easily absorbs moisture in the sealing resin by filling the sealing resin with an inorganic filler, A method of using an inorganic filler whose surface is treated with a silane coupling agent or the like has been studied.

However, a release agent is added to improve the releasability,
Further, when a sealing resin having improved solder crack resistance by adding a high proportion of an inorganic filler is used for sealing, the adhesion strength between the lead frame and the resin cured product may decrease. If the adhesion strength between the lead frame and the resin cured product decreases, the package surface will swell when sealing large discrete components such as large transistors, and even small components will be affected by the thermal shock of soldering. In some cases, cracks may occur between the lead frame and the resin cured product, and there is a demand for an encapsulating resin capable of encapsulating with high adhesive strength with the lead frame while satisfying the mold releasability from the mold. .

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is a sealing material containing an epoxy resin, a curing agent, an inorganic filler, a release agent and a coupling agent. A sealing resin (epoxy resin composition for encapsulating material), in which an inorganic filler is contained in a high proportion, in the encapsulating resin, the adhesive strength between the lead frame and the resin cured product and the die and resin curing It is an object of the present invention to provide a sealing resin capable of sealing with excellent releasability from an object. Another object of the present invention is to provide a semiconductor device using the sealing resin and having excellent adhesive strength between a lead frame and a cured resin.

[0007]

[Means for Solving the Problems] In order to solve the above problems, the inventors have conducted various studies and as a result, compounded a compound having a structure represented by the following formula (a) as a release agent, and conducted a coupling. The inventors have found that when organosilazane is blended as an agent, the adhesive strength between the lead frame and the resin cured product is excellent, and the mold releasing property with respect to the mold can be excellently sealed, and the problem has been solved.

The encapsulation resin (epoxy resin composition for encapsulant) according to claim 1 of the present invention is an encapsulation compounded with an epoxy resin, a curing agent, an inorganic filler, a release agent and a coupling agent. In a sealing resin containing 60 to 95 parts by weight of an inorganic filler in 100 parts by weight of a resin, a compound having a structure represented by the following formula (a) is contained as a release agent, and an organo compound is used as a coupling agent. It is characterized by containing silazane.

[0009]

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The sealing resin according to a second aspect of the present invention is the sealing resin according to the first aspect, characterized in that the organosilazane has a silicon number of 1 to 4.

The encapsulating resin according to claim 3 of the present invention is the encapsulating resin according to claim 1 or 2, wherein a compound having a structure represented by the above formula (a) is added to the encapsulating resin. 1
It is characterized by containing 0.05 to 0.5 parts by weight with respect to 00 parts by weight.

The sealing resin according to claim 4 of the present invention is the sealing resin according to any one of claims 1 to 3, in which organosilazane is added to 100 parts by weight of the sealing resin. It is characterized by containing 2 to 1.0 parts by weight.

A sealing resin according to a fifth aspect of the present invention is the sealing resin according to any one of the first to fourth aspects, wherein the epoxy resin contains a biphenyl type epoxy resin. And

The sealing resin according to claim 6 of the present invention is the sealing resin according to any one of claims 1 to 5, wherein the epoxy resin contains a dicyclopentadiene type epoxy resin. Is characterized by.

A semiconductor device according to a seventh aspect of the present invention is obtained by encapsulating a semiconductor element mounted on a lead frame using the encapsulating resin according to any one of the first to sixth aspects. Is characterized by.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The encapsulating resin of the present invention comprises at least an epoxy resin, a curing agent, an inorganic filler, a compound having a structure represented by the above formula (a) as a release agent, and an organosilazane as a coupling agent. Is compounded. It is important that the compound having the structure represented by the above formula (a) and the organosilazane are blended together, and if they are not blended together or if only one is blended, the lead frame and the resin The adhesive strength of the cured product decreases.

The compound having the structure represented by the above formula (a) is added to 0.05 parts by weight with respect to 100 parts by weight of the sealing resin.
It is preferable that the content is ˜0.5 parts by weight. 0.05
When the amount is less than the weight part, the effect of improving the adhesive strength of the lead frame and the resin cured product is small, and even when the amount exceeds 0.5 part by weight, there is no difference in the adhesive strength of the lead frame and the resin cured product, which is economical. Not relevant.

The release agent is not limited to the compound having the structure represented by the above formula (a) alone, and if necessary, natural carnauba, stearic acid, Straight-chain fatty acids such as montanic acid, metal salts thereof, esters thereof and the like may be blended.

Organosilazane is a silane coupling agent represented by the following formula (b). In the formula (b), n
Represents 0 or a positive integer, and R ^{1 to} R ⁸ each represent hydrogen or a hydrocarbon group having 1 to 3 carbon atoms.

[0020]

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The organosilazane is added to the sealing resin 10
It is preferable to mix 0.2 to 1.0 parts by weight with respect to 0 parts by weight. If it is less than 0.2 parts by weight, the effect of improving the adhesive strength of the lead frame and the cured resin is small, and if it exceeds 1.0 parts by weight, the filler agglomerates in the sealing resin, causing a problem. Becomes Note that organodisilazane in which n in the formula (b) is 0 is preferable because it has a large effect of improving the adhesive strength of the lead frame and the cured resin.

The coupling agent is not limited to the one containing only organosilazane, and if necessary, the dispersibility of the inorganic filler is improved, and further the chemical bond with the epoxy resin is added. In order to strengthen the resin, epoxysilane, aminosilane, etc. may be blended. Further, these coupling agents may be directly added to the sealing resin, but the inorganic filler may be directly sprayed onto the inorganic filler in advance, or the inorganic filler may be immersed in a solution in which the coupling agent is dissolved. When the filler is added to the sealing resin after the filler is treated with the coupling agent, the effect of improving the adhesive strength between the sealing resin and the lead frame, etc. is ensured compared with the case where it is added directly to the sealing resin. It is possible to obtain and is preferable.

The epoxy resin used in the present invention is not particularly limited, and examples thereof include orthocresol novolac type epoxy resin, bisphenol A type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin. , Heterocyclic epoxy resins and the like, and these may be used alone or in combination of two or more kinds.

When the biphenyl type epoxy resin represented by the following formula (c) is contained in the encapsulating resin, the epoxy resin having high toughness when cured is preferable because the moisture absorption solder cracking property is improved. This resin is preferred because it improves the moldability when sealing a semiconductor element, a lead frame, etc. In the formula (c), R ^{11 to} R ¹⁴ each represent hydrogen or a methyl group.

[0025]

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When the epoxy resin contains a dicyclopentadiene type epoxy resin represented by the following formula (d), the moisture absorption reliability and moisture absorption solder cracking property can be improved, which is preferable. In the formula (d), m represents 0 or a positive integer.

[0027]

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The curing agent used in the present invention is not particularly limited as long as it can be cured by reacting with an epoxy resin. For example, phenol novolac resin and its derivative, cresol novolac resin and its derivative,
Mono- or dihydroxynaphthalene novolac resin and its derivatives, phenol-based curing agents such as condensation products of phenols and naphthols with p-xylene, copolymers of dicyclopentadiene and phenol, amine-based curing agents, acid anhydrides, etc. Is mentioned. The above curing agents may be used alone or in combination of two or more. Note that the use of a phenol novolak resin is preferable because the moisture absorption of the cured resin can be reduced. The compounding amount thereof is usually 0.1 to 10 in terms of an equivalent ratio to the epoxy resin.

The inorganic filler used in the present invention is not particularly limited, and examples thereof include crystalline silica, fused silica, alumina, magnesia, titanium oxide, calcium carbonate, magnesium carbonate, silicon nitride, talc, calcium silicate and the like. Can be mentioned. The inorganic filler may be used alone or in combination of two or more. When silica such as crystalline silica or amorphous silica is used as the inorganic filler, the linear expansion coefficient of the cured resin is small, which is preferable. In addition, the inorganic filler in 100 parts by weight of the sealing resin,
It is important to contain 60 to 95 parts by weight. If it is less than 60 parts by weight, the moisture absorption of the resin cured product may increase and the solder crack resistance may decrease, which is a problem. However, the moldability of is reduced, which is a problem. When an inorganic material is blended in the encapsulating resin as a flame retardant, a colorant, etc., the weight part is calculated in addition to the weight of the inorganic filler.

If desired, the encapsulating resin of the present invention may contain a curing accelerator, a coloring agent, a stress reducing agent, an ion trap agent, a flame retardant and the like. Examples of the curing accelerator include tertiary amine compounds such as 1,8-diaza-bicyclo (5,4,0) undecene-7, triethylenediamine, benzyldimethylamine, 2-methylimidazole, and 2-ethyl-4-methyl. Imidazole compounds such as imidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, triphenylphosphine,
Examples thereof include organic phosphine compounds such as tributylphosphine. As the colorant, for example, carbon black,
Titanium oxide and the like can be mentioned. 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.
Two or more kinds of these curing accelerators, coloring agents, stress reducing agents, ion trap agents, flame retardants and the like can be used in combination.

The sealing resin of the present invention is preferably uniformly mixed and kneaded. As a method of kneading, for example, a sealing resin is manufactured by heating using a roll, a kneader, a mixer, or the like, and then cooling, pulverizing, or the like.

[0032]

【Example】

(Examples 1 to 4, Comparative Examples 1 to 5, Reference Example) As a sealing resin, the following four types of epoxy resins, two types of inorganic fillers, two types of release agents, two types of coupling agents, A curing agent, a curing accelerator, a colorant and a flame retardant were blended in the weight ratios shown in Tables 1 and 2. The ratio of the release agent of the formula (a) in Tables 1 and 2 is based on 100 parts by weight of the sealing resin.
The part by weight of the compound having the structure represented by the above formula (a) is represented, and the organosilazane ratio represents the part by weight of organosilazane relative to 100 parts by weight of the sealing resin. -Epoxy resin a: Ortho-cresol novolac type epoxy resin [Sumitomo Chemical Co., Ltd., trade name ESCN195XL] -Epoxy resin a: represented by the above formula (c), R ^{11 to} R ¹⁴
Is a biphenyl type epoxy resin [made by Yuka Shell Epoxy Co., trade name YX4000H] -Epoxy resin C: Dicyclopentadiene type epoxy resin represented by the above formula (d) [manufactured by Dainippon Ink and Co., trade name EXA7200] -Epoxy resin d: Tetrabromobisphenol A type epoxy resin [Sumitomo Chemical Co., Ltd., trade name ESB-400T] -Curing agent: Phenolic resin [Arakawa Chemical Co., Ltd., trade name Tamanol 752] -Inorganic filler F: Melt Silica [Tatsumori Co., product name RO
8] -Inorganic filler K: crystalline silica [Tatsumori Co., trade name 3K] -Release agent: natural carnauba [Dainichi Chemical Co., trade name F-
1-100] -Release agent Si: Compound having structure represented by the above formula (a) [Hoechst, trade name NC133] -Coupling agent: γ-glycidoxypropyltrimethoxysilane [Toray Dow Corning, product name SH6
040] -Coupling agent H: hexamethyldisilazane [Toray Dow Corning, trade name SZ6079] -Curing accelerator: 2-phenylimidazole-Colorant: carbon black-Flame retardant: antimony trioxide

[0033]

[Table 1]

[0034]

[Table 2]

The above-mentioned coupling agent was blended after being directly sprayed onto the inorganic filler in advance for surface treatment.
After mixing each of the above raw materials, the mixture was kneaded with a heating roll at a temperature of 85 ° C. for 5 minutes and then cooled. Then, it was pulverized to obtain a sealing resin.

(Evaluation) Using the sealing resins obtained in Examples 1 to 4, Comparative Examples 1 to 5 and Reference Example, an evaluation sample was prepared by the following method, and the adhesive strength of the evaluation sample was evaluated.
Moisture absorption Solder cracking property, moisture absorption reliability, moisture absorption rate, burr size, releasability and number of package blisters were measured by the following methods.

The adhesive strength is such that a flat plate made of a 42 alloy alloy having a thickness of 0.5 mm has a diameter of 11.3 mm and a height of 1 cm on one side.
The pudding-type molded product of 1 was molded and then post-cured to prepare a sample for evaluation. The obtained sample for evaluation was pulled in the shearing direction using a push-pull gauge to determine the strength at the time of breaking. The molding and post-curing methods were carried out by using a transfer molding machine at a temperature of 170 ° C. for 90 seconds and then at a temperature of 175 ° C. for 6 hours.

Moisture absorption solder cracking property is 9.6 × 9.6.
After bonding a semiconductor element of × 0.4 mm to a lead frame made of 42 alloy alloy having a thickness of 150 μm with a silver paste,
A 15 pin × 19 × 2.4 mm 60-pin QFP type evaluation sample was molded and post-cured in the same manner as the adhesive strength evaluation sample. Next, this evaluation sample 1
After 0 pieces were subjected to moisture absorption treatment under the condition of 85 ° C./85% RH for 72 hours, they were immersed in solder at 250 ° C. for 10 seconds and heated. Next, the sample for evaluation was cut in half, the cut surface was polished, and then the presence or absence and the size of cracks starting from the end of the die pad were observed with a microscope. Crack size is 75μ
Those with m or more were regarded as defective.

Regarding the moisture absorption reliability, a sample for evaluation similar to the evaluation of the moisture absorption solder cracking property was prepared, subjected to the moisture absorption treatment and the solder dipping treatment similar to the evaluation of the moisture absorption solder cracking property, and then at 133 ° C./85% RH. PCT processing of condition 200
Time and 500 hours. Next, the sample for evaluation was cut in half, the cut surface was polished, and then the presence or absence and the size of cracks starting from the end of the die pad were observed with a microscope. A crack having a size of 75 μm or more was regarded as defective.

Regarding the moisture absorption rate, a disk type evaluation sample having a diameter of 50 mm and a thickness of 3 mm was molded and post-cured in the same manner as the adhesive strength evaluation sample to prepare, and then dried at a temperature of 125 ° C. for 16 hours, Then, after moisture absorption treatment was performed for 72 hours under the condition of 85 ° C./85% RH, the difference from the weight immediately after being dried at a temperature of 125 ° C. for 16 hours was measured, and the increase rate was calculated.

The size of the burr is such that it has a disc-shaped sample sealing portion and a slit portion formed in a direction orthogonal to the disc from the side surface of the disc so that the clearance between the upper die and the lower die is 20 μm. Using the measurement mold, the sealing resin is injected into the disk-shaped sample sealing portion, and only the molding is performed in the same manner as the adhesive strength evaluation sample.
This was produced. Next, the length of the burr flowing out through the slit portion generated in the portion corresponding to the slit portion of this evaluation sample was measured, and the average value was obtained.

The mold releasability was evaluated by visually observing the demolded state from the mold when molding the sample for evaluating the moisture absorption solder cracking property and the sample for evaluating the moisture absorption reliability. When something that adheres to the upper mold or the lower mold and does not separate does not occur, it was determined to be unacceptable (x).

The number of package blisters generated is 15 × 20 ×
Ten 5 mm TOP-3F transistor type evaluation samples were molded in the same manner as the adhesive strength evaluation sample, and the state of blister generation on the surface of the evaluation sample was visually observed and evaluated.

(Results) As shown in Tables 1 and 2, Example 1 is a comparative example in which one or both of the compound having the structure represented by the above formula (a) and the organosilazane are not blended. The adhesive strength is better than those of Examples 1 to 3, and Example 2 has an adhesive strength as compared with Comparative Example 4 in which neither the compound having the structure represented by the formula (a) nor the organosilazane is blended. Was confirmed to be good. In addition, it was confirmed that each of the examples has a good releasability as compared with the reference example in which the release agent is not mixed. In addition, Example 1 in which crystalline silica having a large coefficient of thermal expansion is blended as an inorganic filler,
Similarly, it was confirmed that the number of package blisters was good as compared with Comparative Examples 1 to 3 in which crystalline silica was blended.

In addition, Example 2 and Example 3 containing the biphenyl type epoxy resin, compared with Example 1,
The adhesive strength, the moisture absorption solder cracking property, the moisture absorption reliability and the moisture absorption rate are good, and Example 4 and Example 5 containing the dicyclopentadiene type epoxy resin are the same as Example 1.
It was confirmed that the adhesive strength, the moisture absorption solder cracking property, the moisture absorption reliability, and the moisture absorption rate were better than those of Comparative Example 1.

[0046]

The encapsulating resin (epoxy resin composition for encapsulating material) according to claims 1 to 6 of the present invention encapsulates a compound having a structure represented by the above formula (a) and an organosilazane. Even if it is a sealing resin that contains a high proportion of an inorganic filler because it is compounded with a stop resin, if sealing is performed using this sealing resin, the adhesive strength between the lead frame and the cured resin and the gold A sealed product having excellent releasability from the mold can be obtained.

When the encapsulating resin according to claim 5 or 6 of the present invention is used for encapsulation, in addition to the above effects,
A sealed product having excellent moisture absorption reliability can be obtained.

A semiconductor device according to claim 7 of the present invention is sealed with a sealing resin obtained by blending a compound having a structure represented by the above formula (a) and organosilazane with a sealing resin. Therefore, the semiconductor device has excellent adhesive strength between the lead frame and the cured resin.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hironori Ikeda 1048 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Works, Ltd.

Claims (7)

[Claims] 1. An inorganic filler is contained in an amount of 60 to 9 in 100 parts by weight of an epoxy resin composition for a sealing material, which comprises an epoxy resin, a curing agent, an inorganic filler, a release agent and a coupling agent.
In the epoxy resin composition for encapsulant containing 5 parts by weight, a compound having a structure represented by the following formula (a) is contained as a release agent, and organosilazane is contained as a coupling agent. A characteristic epoxy resin composition for a sealing material. Embedded image 2. The epoxy resin composition for a sealing material according to claim 1, wherein the organosilazane has a silicon number of 1 to 4. 3. A compound having a structure represented by the above formula (a) is contained in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the epoxy resin composition for a sealing material. The epoxy resin composition for a sealing material according to claim 1 or 2. 4. The organosilazane is contained in an amount of 0.2 to 1.0 parts by weight with respect to 100 parts by weight of the epoxy resin composition for a sealing material.
An epoxy resin composition for a sealing material according to any one of 1. 5. The epoxy resin composition for a sealing material according to claim 1, wherein the epoxy resin contains a biphenyl type epoxy resin. 6. The epoxy resin composition for encapsulants according to claim 1, wherein the epoxy resin contains a dicyclopentadiene type epoxy resin. 7. A semiconductor device obtained by encapsulating a semiconductor element mounted on a lead frame, using the epoxy resin composition for encapsulant according to claim 1. Description: