JPH10182939A - Epoxy resin composition for sealing material and semiconductor device produced by using the composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition capable of forming a seal having excellent wet heat-resistance and wet electrical reliability even in the case of using an inorganic filler and a dicyclopentadiene-type epoxy resin at high ratios and useful in the field of semiconductor device by using a specific inorganic compound and a curing agent as essential components. SOLUTION: This resin composition for sealing is produced by compounding (A) an epoxy resin containing >=30wt.% of a dicyclopentadiene-type epoxy resin with (B) a curing agent containing e.g. >=30wt.% of a compound of formula I ((m) is 0-5) and (C) an inorganic filler. The amount of the component C in the composition is 70-95wt.%. The composition further contains (D) e.g. 0.2-2wt.% of a compound of formula II ((v) is 0-0.3; (w) is 0.5-2.0; (x) is 3.0-5.0; (y) is 0.4-2.0; (z) is 0.1-0.5; (n) is 1-27).

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 a sealing material used for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a method for sealing electronic parts such as semiconductor devices, a method using a ceramic or a thermosetting resin has been used. Above all, sealing with an epoxy resin composition is more preferable than the balance between economy and performance, and is widely used. The semiconductor device sealed with this epoxy resin composition is, for example, a semiconductor element is mounted on a metal lead frame, and the semiconductor element and the lead frame are electrically connected using a bonding wire or the like. And a part of the lead frame is sealed with an epoxy resin composition for a sealing material (hereinafter referred to as a sealing resin).

[0005] As a method of sealing with this sealing resin, transfer molding is generally performed. The sealing resin used in the transfer molding is preferably a solid one at room temperature, and a cresol novolak type epoxy resin is used as an epoxy resin, and a phenol novolak resin is used as a curing agent for the epoxy resin. Commonly used.

When a cured product of a sealing resin (hereinafter referred to as a cured resin) absorbs moisture, the semiconductor device sealed with the sealing resin absorbs moisture due to thermal shock of soldering when the semiconductor device is mounted. In some cases, the water rapidly expands and cracks occur inside the cured resin or between the cured resin and the lead frame, resulting in a problem that reliability is reduced. Therefore, as an improvement in moisture absorption heat resistance, by blending a high proportion of an inorganic filler in the sealing resin, the proportion of the epoxy resin, which is a component that easily absorbs moisture, in the sealing resin is reduced, and the moisture absorption of the cured resin is reduced. A method of reducing the thermal expansion coefficient while reducing the amount, a method of blending an epoxy resin having a molecular structure with high moisture resistance, and the like are being studied.

As a method of using an epoxy resin having a molecular structure having high moisture resistance, for example, Japanese Patent Application Laid-Open No. 61-293
No. 219, a method using a dicyclopentadiene-type epoxy resin is being studied. However, in order to improve moisture absorption heat resistance in particular, a high ratio of inorganic filler is contained in the sealing resin, and a high ratio of dicyclopentadiene type epoxy resin is contained in all epoxy resins to improve the moisture absorption heat resistance. In the case of improvement, the aluminum wiring formed on the surface of the semiconductor element may be corroded, and the reliability of the humidity resistance of the semiconductor device may be reduced.

Therefore, even when the sealing resin contains a high proportion of the inorganic filler and the dicyclopentadiene type epoxy resin contains a high proportion of the whole epoxy resin, the moisture absorption heat resistance is reduced. There is a need for a sealing resin capable of performing sealing with excellent moisture resistance and electrical reliability without performing sealing.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above problems, and is directed to a sealing resin (epoxy for sealing material) comprising an epoxy resin, a curing agent and an inorganic filler. Resin composition), in which the sealing resin contains a high proportion of an inorganic filler and the dicyclopentadiene-type epoxy resin contains a high proportion of the entire epoxy resin. Without reducing heat resistance
An object of the present invention is to provide a sealing resin capable of sealing with excellent moisture resistance and electric reliability. It is another object of the present invention to provide a semiconductor device using the sealing resin and having excellent moisture absorption heat resistance and humidity electric reliability.

[0008]

The sealing resin (epoxy resin composition for sealing material) according to claim 1 of the present invention is a sealing resin obtained by mixing an epoxy resin, a curing agent and an inorganic filler. In addition, 70 parts of the inorganic filler is added to 100 parts by weight of the sealing resin.
９５95 parts by weight, and 100 parts by weight of the total epoxy resin, 30 to 30 parts by weight of the dicyclopentadiene type epoxy resin
In the encapsulating resin containing 100 parts by weight, the encapsulating resin also contains a compound represented by the following formula (a) and a phenol resin represented by the following formula (b) as a curing agent. It is characterized by the following.

[0009]

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[0010]

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The sealing resin according to a second aspect of the present invention is characterized in that the epoxy resin also contains a bisphenol A type epoxy resin having an epoxy equivalent of 300 to 700.

According to a third aspect of the present invention, there is provided a semiconductor device in which a semiconductor element is sealed using the sealing resin according to the first or second aspect.

According to the present invention, the compound represented by the formula (a) captures ionic impurities such as alkali metal cations and organic acid anions in the sealing resin to reduce the influence of the ionic impurities. It is thought that reliability is improved. In addition, the compound represented by the formula (a) does not hinder the effect of lowering the moisture absorption rate in the cured resin of the phenolic resin represented by the formula (b), so that the moisture absorption heat resistance is reduced. Without this, it is considered that the sealing resin can be sealed with excellent moisture resistance and electric reliability.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The sealing resin according to the present invention comprises at least an epoxy resin, a curing agent, an inorganic filler and a compound represented by the above formula (a).

The epoxy resin used in the present invention includes:
It is important that the dicyclopentadiene type epoxy resin is contained in an amount of 30 to 100 parts by weight based on 100 parts by weight of the total epoxy resin. If the amount is less than 30 parts by weight, the moisture absorption rate may increase and the moisture absorption heat resistance may decrease. The dicyclopentadiene type epoxy resin includes, for example, compounds represented by the following formulas (c) and (d).

[0016]

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[0017]

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The epoxy resin used in the present invention includes:
The dicyclopentadiene type epoxy resin is not limited to only the dicyclopentadiene type epoxy resin.
When compounded so as to contain 30 parts by weight or more in 100 parts by weight of all epoxy resins, for example, cresol novolak type epoxy resin, bisphenol A type epoxy resin, phenol novolak type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin , An alicyclic epoxy resin, an epoxy resin flame-retarded by halogenating a part of hydrogen atoms in these epoxy resin structures, and the like. More than one type may be used in combination.

The use of a bisphenol A type epoxy resin having an epoxy equivalent of 300 to 700 is particularly preferred because of its excellent moisture absorption heat resistance. This bisphenol A type epoxy resin is a compound synthesized from bisphenol A and epichlorohydrin and having epoxy groups at both ends.
Bisphenol A having an epoxy equivalent of 300 to 700
It is considered that the crosslinked epoxy resin adjusts the crosslink density of the cured resin by crosslinking with the dicyclopentadiene type epoxy resin, and becomes a cured resin having an appropriate elastic modulus at the time of heating.

When the epoxy equivalent of the bisphenol A type epoxy resin is less than 300, the viscosity of the epoxy resin decreases, so that it becomes difficult to obtain a sealing resin suitable for transfer molding. This is a problem because the reactivity of the sealing resin is reduced. In the case of a halogenated bisphenol A type epoxy resin in which some of the hydrogen atoms in the structure are replaced with halogen atoms such as bromine atoms in order to improve the flame retardancy, when the halogen atoms are replaced with hydrogen. It is preferable to use a resin having an epoxy equivalent of 300 to 700 in combination, since a cured resin having excellent heat resistance to moisture absorption and excellent flame retardancy can be obtained.

When a bisphenol A type epoxy resin is used in combination, 100 parts by weight of all epoxy resins are
10 to 50 parts by weight of bisphenol A type epoxy resin,
More preferably, the content is 20 to 40 parts by weight.
If the amount exceeds 50 parts by weight, the glass transition temperature of the cured resin may be lowered and the heat resistance may be reduced. If the amount is less than 10 parts by weight, the effect of adjusting the crosslinking density of the cured resin is not obtained. .

It is important that the curing agent used in the present invention contains a phenol resin represented by the above formula (b). If it is not contained, the moisture absorption heat resistance may decrease. The phenolic resin represented by the above formula (b) is a phenolic resin generally called a dicyclopentadiene-type phenolic resin, and when an epoxy resin is cured using this phenolic resin, the effect of reducing the moisture absorption rate in the resin cured product is reduced There is.

The curing agent used in the present invention includes:
It is not limited only to the phenolic resin represented by the above formula (b), but includes, for example, a phenol novolak resin and its derivative, a cresol novolak resin and its derivative,
Mono- or dihydroxynaphthalene novolak resins and derivatives thereof, condensates of phenols or naphthols with p-xylene, amine-based curing agents, acid anhydrides, and the like are included. These curing agents may be used alone or in combination of two or more.

When a curing agent other than the phenol resin represented by the above formula (b) is contained, the above formula (b)
When the phenolic resin represented by the formula (1) is contained in a weight ratio of 30% or more, the heat resistance to moisture absorption is particularly excellent, which is preferable. The compounding amount of the entire curing agent is usually 0.1 to 10, preferably 0.7 to 1.3 in 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. No. The inorganic filler may be used alone or in combination of two or more. Note that when silica such as crystalline silica or fused silica is used as the inorganic filler, the coefficient of thermal expansion of the cured resin becomes small, which is preferable because it approaches the coefficient of thermal expansion of the semiconductor element.

It is important to add 70 to 95 parts by weight of the inorganic filler to 100 parts by weight of the sealing resin.
If less than 70 parts by weight, the moisture absorption of the cured resin increases,
In some cases, the heat resistance to moisture absorption is reduced. If the heat resistance is more than 95 parts by weight, the viscosity of the sealing resin increases, and the moldability at the time of sealing decreases, which is a problem. When an inorganic substance is blended in the sealing resin as a flame retardant, a colorant, or the like, the above parts by weight are calculated in addition to the weight of the inorganic filler. In addition, as the inorganic filler, an inorganic filler having an average particle size of about 0.5 to 50 μm is preferable because a sealing resin suitable for transfer molding can be easily manufactured.

It is important that the sealing resin also contains the compound represented by the above formula (a). If it is not contained, the moisture resistance electrical reliability may decrease. When the compound represented by the formula (a) is contained, an alkali metal cation, an alkaline earth metal cation,
It is considered that the moisture resistance electric reliability is improved because organic acid anions, halogen anions and the like are trapped to reduce ionic impurities. The compound represented by the formula (a) is preferably compounded in an amount of 0.2 to 2 parts by weight based on 100 parts by weight of the sealing resin. If less than 0.2 parts by weight,
The effect of improving the wet electric reliability is small, and even if the amount exceeds 2 parts by weight, there is no difference in the effect of improving the wet electric reliability, so that it is not economical.

The sealing resin may contain a curing accelerator, a silane coupling agent, a release agent, a coloring agent, a low stress agent, a surfactant, a flame retardant, and the like, if necessary.

As the curing accelerator that can be contained in the sealing resin, for example, 1,8-diaza-bicyclo (5,
(4,0) tertiary amine compounds such as undecene-7, triethylenediamine, benzyldimethylamine, 2-methylimidazole, 2-ethyl-4-methylimidazole,
Examples thereof include imidazole compounds such as 2-phenylimidazole and 2-phenyl-4-methylimidazole, and organic phosphine compounds such as triphenylphosphine and tributylphosphine.

Examples of the silane coupling agent that can be contained in the sealing resin include epoxy silanes such as γ-glycidoxypropyltrimethoxysilane and aminosilanes such as N-phenyl-γ-aminopropyltrimethoxysilane. And the like. The silane coupling agent may be added directly to the sealing resin.However, the inorganic filler may be sprayed directly on the inorganic filler in advance, or the inorganic filler may be immersed in a solution in which the silane coupling agent is dissolved. The method of adding the filler to the sealing resin after treating the filler with the silane coupling agent has lower adhesiveness and moldability between the cured resin and the lead frame compared to the case of adding the filler directly to the sealing resin. Excellent and preferred.

Examples of the release agent that can be contained in the sealing resin include fatty acids such as stearic acid, montanic acid, palmitic acid, oleic acid, and linoleic acid, and calcium, magnesium, and aluminum salts of the fatty acids. Examples include salts such as zinc salts, amides and phosphates of fatty acids thereof, polyethylene, bisamide, carboxyl group-containing polyolefin, and natural carnauba.

Examples of the coloring agent that can be contained in the sealing resin include carbon black and titanium oxide. Examples of the low-stressing agent that can be contained in the sealing resin include silicone gel, Silicone rubber, silicone oil, and the like, and examples of surfactants that can be contained in the sealing resin include, for example, polyethylene glycol fatty acid ester, sorbitan fatty acid ester, and fatty acid monoglyceride. Examples of possible flame retardants include antimony trioxide, halogen compounds, phosphorus compounds and the like.

Two or more of these curing accelerators, silane coupling agents, release agents, coloring agents, low stress agents, surfactants, and flame retardants can be used in combination.

It is preferable that the sealing resin of the present invention is 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.

When a semiconductor element, a lead frame, and the like are sealed by performing transfer molding or the like using the sealing resin obtained above, a semiconductor device having excellent moisture absorption heat resistance and humidity electric reliability is obtained. . The method of molding is not particularly limited except that the above sealing resin is used, and molding can be performed by a general method.

[0036]

【Example】

(Examples 1-3, Comparative Examples 1-3, Reference Examples) As a raw material of the sealing resin, the following four types of epoxy resins, two types of curing agents, a curing accelerator, an inorganic filler, and the above formula (a) , A silane coupling agent, a release agent, a flame retardant, and a colorant. -Epoxy resin 1: dicyclopentadiene type epoxy resin [HP7200, trade name, manufactured by Dainippon Ink and Chemicals, Inc .; epoxy equivalent: 285]-Epoxy resin 2: bisphenol A type epoxy resin [trade name, Epicoat 100, manufactured by Yuka Shell Epoxy Co., Ltd.]
1] (Epoxy equivalent 475) Epoxy resin 3: Brominated bisphenol A type epoxy resin (Epoxy equivalent 170) Epoxy resin 4: Cresol novolac type epoxy resin [ESCN195XL, trade name, manufactured by Sumitomo Chemical Co., Ltd.] (Epoxy equivalent 195) Curing agent 1: Phenol resin represented by the above formula (b) [Nippon Petrochemical Co., Ltd., trade name DPP-M] Curing agent 2: Phenol novolak resin [Gunei Chemical Co., trade name PSM6200] Curing acceleration Agent: triphenylphosphine [manufactured by Hokko Chemical Industry Co., Ltd.]-Inorganic filler: fused silica [manufactured by Tatsumori Co., trade name: RO8]-Compound represented by the above formula (a): [manufactured by Towa Gosei Co., Ltd., trade name: IXE600] • Silane coupling agent: γ-glycidoxypropyltrimethoxysilane [Toray Dow Corning Co., trade name S
H6040]-Release agent: natural carnauba [Dainichi Kagaku Co., trade name F-1]
-100] Colorant: carbon black Flame retardant: antimony trioxide.

Each of the above raw materials was blended in the weight ratio shown in Table 1.
After mixing, the mixture was kneaded at a temperature of 85 ° C. for 5 minutes using a heating roll, and then cooled. Then, it was pulverized to obtain a sealing resin. In Table 1, “compound of formula (a)” represents a compound represented by the above formula (a), and “formula (b) phenol resin” represents a phenol resin represented by the above formula (b).

[0038]

[Table 1]

(Evaluation) Using the sealing resins obtained in Examples 1 to 3, Comparative Examples 1 to 3, and Reference Examples, samples for evaluation were prepared by the following method, and the electrical resistance to moisture, the heat resistance to moisture absorption, The moisture absorption rate and the elastic modulus during heating were measured by the following methods.

The moisture resistance electrical reliability was determined by bonding a 9.6 × 9.6 × 0.4 mm test element on which a 10 μm wide aluminum wiring was formed to a 150 μm thick 42 alloy alloy lead frame with a silver paste. Then, it was molded and post-cured using a sealing resin to prepare a 15 × 19 × 2.4 mm 60-pin QFP type evaluation sample. Next, the sample for evaluation was subjected to a moisture absorption treatment under the condition of 85 ° C./85% RH for 72 hours, and then dipped in 250 ° C. solder for 10 seconds and heated. Next, after performing PCT processing under the conditions of 133 ° C./100% RH for 200 hours and 500 hours, the number of samples in which aluminum wiring was open in each of ten evaluation samples was determined.

Similarly, after moisture absorption treatment and solder immersion treatment, USPCBT treatment at 138.5 ° C./85% RH / 25 V was performed for 500 hours. The number of samples where an open occurred was determined.

The molding and post-curing 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.

The heat resistance to moisture absorption is 9.6 × 9.6 × 0.4 m
Using the semiconductor device of m, a sample for evaluation similar to the evaluation of the moisture resistance reliability was prepared, and after performing the same moisture absorption treatment and solder immersion treatment as the evaluation of the humidity resistance resistance, the evaluation sample was cut in half. Then, after the cut surface was polished, the presence or absence of cracks inside the cured resin or between the cured resin and the lead frame was observed with a microscope. Crack size is 7
Samples for evaluation of 10 μm or more
The number of defective samples in each piece was determined.

The moisture absorption was determined by molding and post-curing a disk-shaped evaluation sample having a diameter of 50 mm and a thickness of 3 mm in the same manner as the sample for evaluating the resistance to humidity and electricity.
At 85 ° C./85% RH
After moisture absorption for 72 hours under the conditions of
The difference from the weight immediately after drying for 6 hours was measured, and the increase rate was calculated and obtained. The elastic modulus under heat was determined at 240 ° C. in accordance with JIS K6911.

(Results) As shown in Table 1, the results of Examples are superior in moisture resistance and electric reliability compared to Comparative Examples 1 and 2, and Comparative Example 3 and dicyclopentadiene type epoxy resin are contained. Not equivalent to the reference example, and excellent in moisture absorption heat resistance as compared with the comparative examples 1, 3 and the reference example,
It was confirmed that this was equivalent to Comparative Example 2. That is, it was confirmed that each of the examples had excellent moisture-resistant electrical reliability without lowering the moisture absorption heat resistance.

Further, it was confirmed that Example 2 which contained a bisphenol A type epoxy resin having an epoxy equivalent of 300 to 700 at an appropriate compounding ratio was particularly excellent in moisture absorption heat resistance as compared with Examples 1 and 3. .

[0047]

According to the first and second aspects of the present invention, the sealing resin (the epoxy resin composition for a sealing material) comprises a compound represented by the above formula (a) in the sealing resin; Since the phenolic resin represented by the formula (b) is blended, sealing with this sealing resin enables sealing with excellent moisture and electric reliability without deteriorating moisture absorption heat resistance. Becomes

According to a third aspect of the present invention, a semiconductor device is sealed by using a compound represented by the above formula (a) and a sealing resin containing a phenol resin represented by the above formula (b). As a result, the semiconductor device has excellent moisture absorption heat resistance and moisture resistance electric reliability.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 23/31

Claims (3)

[Claims] 1. An epoxy resin composition for a sealing material comprising an epoxy resin, a curing agent and an inorganic filler, wherein 100 parts by weight of the epoxy resin composition for a sealing material contains 70 parts of an inorganic filler. -95 parts by weight and total epoxy resin 1
In an epoxy resin composition for a sealing material containing 30 to 100 parts by weight of a dicyclopentadiene type epoxy resin in 00 parts by weight, the epoxy resin composition for a sealing material is represented by the following formula (a). An epoxy resin composition for a sealing material, comprising a compound and a phenol resin represented by the following formula (b) as a curing agent. Embedded image Embedded image 2. An epoxy resin having an epoxy equivalent of 3
2. The epoxy resin composition for a sealing material according to claim 1, further comprising a bisphenol A type epoxy resin of from 00 to 700. 3. A semiconductor device in which a semiconductor element is sealed using the epoxy resin composition for a sealing material according to claim 1.