JPH10158360A - Epoxy resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition having excellent moldability, soldering resistance, etc., by using respectively specific epoxy resin, phenolic resin hardener, brominated epoxy resin, antimony oxide, inorganic ion exchanging material, fused silica powder and cure accelerator as essential components. SOLUTION: This composition contains (A) an epoxy resin containing >=30wt.% (based on the total epoxy resin) of an epoxy compound of the formula (R is H, a 1-9C alkyl, etc.), (B) a phenolic resin hardener having a melt viscosity of <=5 poise at 150 deg.C, (C) a brominated epoxy resin, (D) antimony oxide, (E) at least one inorganic ion exchange material selected from hydrated bismuth oxide and hydrotalcite compound, (F) fused silica powder and (G) a cure accelerator as essential components. The composition satisfies the formulas 0.2<a/b<3.0, 0.03<(a+b)/R<=0.2 and 0.05<c/(a+b)<=3 wherein R is the total weight of the compounded components A to C, (a) is the weight of bromine in the component C, (b) is the weight of antimony in the component D and (c) is the compounding weight of the component E.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to moldability, solder resistance,
The present invention relates to an epoxy resin composition for semiconductor encapsulation which has excellent electrical properties at high temperatures and is particularly suitable for thin semiconductor packages.

[0002]

2. Description of the Related Art Transfer molding of an epoxy resin composition has been employed as a method suitable for mass production at low cost as a method for encapsulating semiconductor devices such as ICs and LSIs. Improvements have been made by improving phenolic resins as curing agents. However, in recent years, with the market trend of miniaturization, weight reduction and high performance of electronic devices, the integration of semiconductors has been increasing year by year, and the surface mounting of semiconductor packages has been promoted. Resin composition (hereinafter referred to as resin composition)
Requirements are becoming increasingly demanding. For this reason, a problem which cannot be solved by the conventional resin composition has come out. The biggest problem is that the package is exposed to a high temperature of 200 ° C or more during the solder immersion or reflow process due to the adoption of the surface mounting of the semiconductor package. In various types of plated joints or LOC structure packages, peeling occurs at each interface between the polyimide tape adhesive or the like and the resin composition, and the reliability is significantly reduced.

Further, in recent years, the thickness of the resin composition occupying in the package has been further reduced with the reduction in the thickness of the package, and a TSOP having a thickness of 1 mm is becoming the mainstream for packages for 64M and 256M DRAMs. These thin packages are required to have good package filling properties at the time of molding the resin composition, to have little gold wire deformation, and to have no chip or lead frame deformation (referred to as chip shift or die pad shift). The composition needs to have excellent fluidity during molding. In order to achieve both the improvement in reliability due to soldering and the improvement in fluidity during molding, the amount of fused silica powder in the resin composition is increased to reduce moisture absorption, increase strength, and reduce thermal expansion. It is becoming common practice to achieve high solderability by improving the solder resistance and using a resin having a low melt viscosity to maintain low viscosity and high fluidity during molding. As the epoxy resin used in this method, there is a crystalline epoxy compound which is solid at normal temperature and extremely lowers in viscosity when melted, and as a typical example, a biphenyl type epoxy compound has begun to be widely used. (Japanese Unexamined Patent Publication No. 5-175364,
343570, JP-A-6-80763, etc.).

However, conventional crystalline epoxy compounds, particularly biphenyl type epoxy compounds, are characterized by low melt viscosity at the molding temperature. However, in the biphenyl structure, which is the main skeleton, the limit of the number of functional groups is only two. In addition, it has been pointed out that there is a problem that the properties of the cured product such as the strength at heat and the glass transition temperature are low. In addition, it has been begun to be regarded as a problem that when a semiconductor package sealed with an epoxy resin composition using a biphenyl type epoxy compound is treated at a high temperature of 150 ° C. or higher for a long time, electric characteristics are deteriorated. It has been found that the cause is largely affected by the low glass transition temperature of the cured product of the biphenyl type epoxy compound, and improvement is desired.

[0005]

DISCLOSURE OF THE INVENTION The present invention has a good filling property in a thin package, and has a small flow of gold wire, chip shift and die pad shift. The object of the present invention is to develop a resin composition having good reliability such as solderability and electric characteristics under a high temperature atmosphere.

[0006]

That is, the present invention provides (A)
An epoxy resin containing 30% by weight or more of the epoxy compound represented by the general formula (1) in the total epoxy resin, (B) 150
A phenol resin curing agent having a melt viscosity at 5 ° C. of 5 poise or less, particularly preferably a phenol resin curing agent represented by the general formula (2), (C) a brominated epoxy resin, (D) antimony oxide, and (E) bismuth oxide water The epoxy resin composition for semiconductor encapsulation comprising at least one inorganic ion exchanger selected from the group consisting of a hydrate and a hydrotalcite compound, (F) a fused silica powder, and (G) a curing accelerator as essential components. Resin, phenolic resin curing agent,
The following relationship is established between the total R of the blended weight of the brominated epoxy resin, the weight a of the bromine atom in the brominated epoxy resin, the weight b of the antimony atom in the antimony oxide, and the blended weight c of the inorganic ion exchanger. An epoxy resin composition for encapsulating a semiconductor having: 0.2 <a / b <3.0, 0.03 <(a + b) / R ≦
0.2 and 0.05 <c / (a + b) ≦ 3

Embedded image (Wherein R is hydrogen, an alkyl group having 1 to 9 carbon atoms,
A group selected from halogen atoms, which may be the same or different. )

Preferably, a phenol resin curing agent having a melt viscosity at 150 ° C. of 5 poise or less is represented by the general formula (2):
It is something that is.

Embedded image (Where m ≧ 0, n ≧ 0, and m + n ≧ 1)

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. The epoxy compound in the component (A) used in the present invention is represented by the general formula (1). Epoxy compounds of this structure
It is usually called stilbene structure type epoxy. Many studies have already been made and many reports have been published.
Some applications to semiconductor sealing materials have also been proposed (JP-A-6-345849, JP-A-8-73562).
Each publication). Since this stilbene skeleton has a rigid planar or rod-like structure, the molecules are easily aligned with each other, and thus is a typical structure of liquid crystal or liquid crystalline polymer. After curing, the resin composition using the epoxy compound having this structure exhibits good heat resistance due to the rigid molecular skeleton of the epoxy compound and the orientation of the molecules. For this reason, compared with the biphenyl type epoxy compound which is a representative of the conventional crystalline epoxy compound, the glass transition temperature and the strength at the time of heat are high,
In addition, it has features such as excellent moisture resistance. Further, since the glass transition temperature is higher than that of the biphenyl type epoxy compound, the deterioration of the electrical characteristics of the semiconductor sealed with the epoxy resin composition using the same in a high temperature atmosphere is higher than in the case where the biphenyl type epoxy compound is used. There are few features. Furthermore, since the epoxy compound having this structure tends to orient the molecules due to shear stress, the resin composition in the mold in low-pressure transfer molding (especially in a structure in which shear stress is easily applied like a thin package) is used. It has high fluidity and is excellent in filling into thin packages. Therefore,
It is an epoxy compound suitable for the resin composition for thin package sealing which is the object of the present invention. Examples of the epoxy compound represented by the general formula (1) include the following formulas (3) to (3).
Formula (5) and the like are included, but not limited thereto.

Embedded image

[0009]

Embedded image

[0010]

Embedded image

The epoxy resin referred to in the present invention includes all monomers, oligomers and polymers having two or more epoxy groups in a molecule. The epoxy resin that can be used in combination with the epoxy compound of the present invention refers to all monomers, oligomers, and polymers having an epoxy group, such as bisphenol A epoxy resin, orthocresol novolac epoxy resin, naphthalene epoxy resin, and triphenolmethane. Type epoxy resin, epoxidized resin of dicyclopentadiene-modified phenols and the like, in particular, in order to obtain a resin composition having excellent solder resistance,
Epoxy compounds that exhibit crystallinity at room temperature, such as biphenol diglycidyl ether, tetramethyl biphenol diglycidyl ether, hydroquinone diglycidyl ether, and tetramethyl bisphenol F diglycidyl ether, are preferred. The epoxy resin used in combination with the general formula (1) may be used alone or as a mixture. The use ratio of the epoxy compound of the present invention is desirably 30% by weight or more in the total epoxy resin. If the content is less than 30% by weight, the high fluidity and high heat resistance at the time of molding, which are characteristics of this crystalline epoxy compound, are not exhibited.

The phenolic resin curing agent (B) used in the present invention is characterized by having a melt viscosity at 150 ° C. of 5 poise or less. When the melt viscosity exceeds 5 poise at 150 ° C., the melt viscosity of the resin composition using the same increases, the fluidity at the time of molding decreases, and the molded product in the mold is not filled, the wire is deformed, and the An inclination (so-called chip shift) occurs, which is not preferable. As a method for measuring the melt viscosity of a phenol resin at 150 ° C., an ICI cone and plate viscometer is simple and general. Phenol resin refers to any monomer, oligomer, or polymer having a phenolic hydroxyl group capable of curing and reacting with an epoxy resin to form a crosslinked structure. Examples include, but are not limited to, modified phenolic resins, bisphenol A, triphenolmethane, and the like. These phenolic resins can be used alone or in combination. Further, the melt viscosity when various phenol resins are used in combination does not indicate the value of the melt viscosity of each phenol resin alone, but the melt viscosity of the melt mixture of all phenol resins used is 5 poise or less at 150 ° C. That is.

From the viewpoint of the solder resistance of the resin composition, a xylylene-modified phenol resin represented by the following general formula (2) is preferable as a particularly effective phenol resin. This phenol resin is synthesized by a polycondensation reaction between phenol and p-xylylene glycol dimethyl ether or m-xylylene glycol dimethyl ether. Since this structure has properties such as low moisture absorption, low elastic modulus during heat, high adhesion to members such as lead frames and chips,
The stress generated when the absorbed moisture is vaporized by the soldering process is reduced, and the effect of preventing the occurrence of package cracks is great. Further, as the ratio of the m-xylylene skeleton to the p-xylylene skeleton in the structure of the general formula (2) increases, the resin composition using the same has a feature that the strength at heat is improved, and the solder resistance is further improved. Tend to be excellent.

The brominated epoxy resin (C) used in the present invention refers to all epoxy resins having a bromine atom in the resin skeleton, and these are well-known flame retardants. Bromine atoms in the brominated epoxy resin exhibit a flame retardant action when the cured product of the epoxy resin composition burns.
Specifically, a tetrabromobisphenol A type epoxy resin, a brominated phenol novolak type epoxy resin and the like are particularly preferable. The component (D) antimony oxide used in the present invention is also well known as a flame retardant and is widely used. Specifically, diantimony trioxide, diantimony tetroxide, diantimony pentoxide and the like are exemplified.

The inorganic ion exchanger of the component (E) used in the present invention is selected from at least one of bismuth oxide hydrate and hydrotalcite compounds. Specific examples of bismuth oxide hydrate include the following, but are not limited thereto. _{BiOx (OH) y (NO 3} ) z, SbBiw Ox (OH) y
(NO ₃ ) z · nH ₂ O, SbSivBiWOx (OH) y
(NO ₃ ) z · nH ₂ O, (w, x, y, and z each represent a positive number and n represents a positive integer) A hydrotalcite compound is represented by the general formula MgxAly (O
H) zCO ₃ .nH ₂ O, where (w, x, y, z, and n each represent a positive number). The inorganic ion exchanger,
By trapping bromine ions released from the brominated epoxy resin compounded in the epoxy resin composition and antimony ions generated from antimony oxide, there is an effect of improving reliability.

The stilbene type epoxy compound of the component (A) has a higher glass transition temperature than other crystalline epoxy compounds typified by the biphenyl type epoxy compound due to its rigid structure. As described above, the reliability of the electrical characteristics is improved. However, since the present epoxy compound is also bifunctional, its glass transition temperature is lower than that of a polyfunctional epoxy resin represented by, for example, a cresol novolak type epoxy resin, and the reliability of electric characteristics under a high-temperature atmosphere is reduced. . Further, the stilbene type epoxy compound has a non-aromatic carbon-hydrogen atom between benzene rings as compared with the biphenyl type epoxy compound, and thus has a disadvantage that it is easily burned. For this reason, unless the flame retardant component is added in a larger amount than the biphenyl type epoxy compound, the flame resistance is not exhibited. However, when the amount of the flame retardant component is increased, bromine atoms derived from the brominated epoxy resin and antimony ions derived from the antimony oxide compound increase. These two ions have a correlation that lowers the electrical characteristics of the semiconductor device under a high-temperature atmosphere, and it is necessary to reduce these ions as much as possible.

The component (E), an inorganic ion exchanger, captures these ions and can prevent a decrease in electric characteristics under a high-temperature atmosphere. Accordingly, the stilbene type epoxy compound (A) can be further improved without impairing its characteristic of being excellent in electric characteristics under a high temperature atmosphere. That is,
It is possible to achieve both high fluidity during molding of an epoxy resin composition using a crystalline epoxy compound and improvement in electrical properties under a high-temperature atmosphere. However, in order to realize this, it is necessary to optimize the compounding amount of the resin component, which is a combustible component, the compounding amount of the flame retardant component, and the compounding amount of the inorganic ion exchanger contained in the epoxy resin composition. Needless to say.

The resin component in the epoxy resin composition includes any of an epoxy resin, a phenol resin curing agent, and a brominated epoxy resin. The sum of the amounts of these resin components is denoted by R, and the amount of bromine atoms in the brominated epoxy resin acting as the flame retardant component of the flame retardant and the amount of antimony atoms in antimony oxide are denoted by a and b, respectively.
Then, it is necessary that the respective compounding amounts have the following relationship. 0.2 <a / b <3.0, 0.03 <(a + b) / R ≦
0.2 Since a bromine atom and an antimony atom exhibit flame retardancy due to an interaction between them, a / b is 0.2 or less or 3.0 or less.
With the above compounding ratio, sufficient flame retardancy cannot be obtained, and the added amount increases, so that the reliability of the electrical characteristics under a high-temperature atmosphere is reduced. When (a + b) / R is 0.03 or less, flame retardancy cannot be obtained. On the other hand, when (a + b) / R exceeds 0.2, the flame retardancy is further improved, but the effect of lowering the electric characteristics under a high-temperature atmosphere is obtained. Becomes large. It is preferable that the compounding amount c of the inorganic ion exchanger has the following relationship with respect to the sum of the above a and b. When 0.05 <c / (a + b) ≦ 3 c / (a + b) is less than 0.05, the ability to trap bromine ions and antimony ions is reduced, and the electrical characteristics and reliability under a high-temperature atmosphere are reduced. On the other hand, when it exceeds 3, the curability of the epoxy resin composition is lowered and the moldability is poor.

The fused silica powder of the component (F) used in the present invention refers to, for example, natural silica melted in a flame and synthetic silica obtained by hydrolyzing tetramethoxysilane, tetraethoxysilane and the like. . In addition, it is classified into spherical silica and crushed silica according to its shape and manufacturing method.
Either of them may be used, but when the filler is highly filled, it is preferable to increase the use ratio of the spherical silica. The compounding amount of the fused silica powder of the component (F) used in the present invention is preferably 75 to 93% by weight in the whole resin composition. If the amount is less than 75% by weight, the molded package will have an increased amount of moisture absorption, and the strength at the soldering temperature will be reduced. On the other hand, when the content exceeds 93% by weight, the fluidity during molding of the resin composition decreases, and unfilling, chip shift, and pad shift tend to occur, which is not preferable.

The curing accelerator of the component (G) used in the present invention may be any as long as it promotes the crosslinking reaction between the epoxy resin and the phenol resin curing agent.
1,8-diazabicyclo (5,4,0) undecene-7
And the like, an organic phosphorus compound such as triphenylphosphine, tetraphenylphosphonium / tetraphenylborate salt, and an imidazole compound such as 2-methylimidazole, but are not limited thereto. These curing accelerators may be used alone or as a mixture. The resin composition of the present invention,
In addition to the components (A) to (G), if necessary, low stress agents represented by polysiloxane compounds, coupling agents, coloring agents represented by carbon black, release agents such as natural waxes and synthetic waxes Etc. can be appropriately compounded. In order to obtain a molding material, after mixing all components, the mixture is heated and kneaded using a heating kneader or a hot roll, and then cooled and pulverized to obtain a desired resin composition.

Hereinafter, the present invention will be described specifically with reference to examples. Example 1 3.8 parts by weight of an epoxy compound represented by the formula (4) (melting point: 146 ° C.)

Embedded image

4.2 parts by weight of a xylylene-modified phenolic resin represented by the formula (6)

Embedded image (However, m is a mixture of at least one, the weight ratio of the components satisfying m ≧ 6 is 32% by weight, the melt viscosity at 150 ° C. is 2.8 poise, and the hydroxyl equivalent is 170.) , Formula (6-1))

A brominated bisphenol A type epoxy resin (bromine content: 50%) 0.5 parts by weight Antimony trioxide (antimony atom content: 84%) 1.0 parts by weight Bismuth oxide hydrate (general formula BiOx (OH) y (NO ₃ ) z (where x = 0.9 to 1.1, y = 0.6 to 0.8, z = 0.2 to 0.4. Trade name IX-500S (Toagosei ( 1.0 part by weight Spherical fused silica powder 88.0 parts by weight 1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) 0.2 part by weight γ-glycid 0.5 parts by weight of xypropyltrimethoxysilane 0.3 parts by weight of carbon black 0.5 parts by weight of carnauba wax After mixing each component using a mixer, the surface temperature was 90%.
The mixture was kneaded 30 times using two rolls at a temperature of 45 ° C. and a temperature of 45 ° C. The obtained kneaded material sheet was cooled and pulverized to obtain a resin composition.
The properties of the obtained resin composition were evaluated by the following methods. Table 1 shows the results.

Evaluation method Spiral flow: Using a mold for spiral flow measurement in accordance with EMMI-I-66, using a mold temperature of 175 ° C.
The measurement was performed at an injection pressure of 70 kg / cm ² and a curing time of 2 minutes. Flame resistance: A combustion test of a 1.0 mm thick test piece was performed according to the UL-94 test method. The results are expressed as the UL-94 flame resistance level. High temperature reliability: Using 16pSOP equipped with a simulation element,
The table shows the processing time until the number of packages at which the electric resistance value becomes twice the initial value after processing at 185 ° C. exceeds 50%. Bacoal hardness: 16 pSOP used in high-temperature reliability evaluation
175 ° C mold temperature, 75kg / cm ²
Transfer molding at a molding pressure of 2 minutes. Measure the surface hardness of the molded product 10 seconds after opening the mold with a Bacoal hardness tester #
Measured at 935. Heat strength: Flexural strength at 240 ° C. is determined according to JIS-K6911.
The test conditions were as follows. Solder resistance: 100-pin TQFP package (package size is 14 x 14 mm, thickness is 1.4 mm, silicon chip size is 8.0 x 8.0 mm, lead frame is 4
2 alloy) at a mold temperature of 175 ° C., 75 kg / cm ²
Transfer molding at an injection pressure of 2 minutes, and 175
Post-curing was carried out at 8 ° C. for 8 hours. 85 molded product packages
It was left for 168 hours in an environment of 85 ° C. and a relative humidity of 85%, and then immersed in a solder bath at 240 ° C. for 10 seconds. The package was observed with a microscope, and external cracks ((number of crack-occurring packages) / (total number of packages) × 100) were displayed in%. Further, the ratio of the peeling area between the chip and the resin composition was measured using an ultrasonic flaw detector, and the peeling rate ((peeling area) /
(Chip area) × 100) was expressed in%.

Examples 2 to 6, Comparative Examples 1 to 8 In place of the composition of Example 1, each component was blended in the ratio shown in Table 1, and mixed and kneaded in the same manner as in Example 1 to obtain a resin composition. Obtained. Tables 1 and 2 show the results of the evaluation performed in the same manner as in Example 1. In addition, the epoxy compound (5) of Example 5 is the same as the formula (5), and has a melting point of 110 ° C.
The biphenyl epoxy compounds of Example 6 and Comparative Example 8 are 3,3 ′, 5,5′-tetramethylbiphenol diglycidyl ether of trade name YX-4000H (manufactured by Yuka Shell Epoxy Co., Ltd.). Type. The structures and resin properties of the phenolic resin (2) used in Example 5, Comparative Example 4 and the phenolic resin (6) used in Comparative Example 7 are shown below.

Embedded image (However, m / n = 3/1 by weight, m + n is a mixture of 1 or more, the weight ratio of the component satisfying m + n ≧ 6 is 40% by weight, and the melt viscosity at 150 ° C. is 3.%). 3 poise,
Hydroxyl equivalent 170) (hereinafter referred to as formula (2-1))

[0026]

Embedded image (However, m is a mixture of at least 1; the weight ratio of components satisfying m ≧ 6 is 60% by weight; the melt viscosity at 150 ° C. is 7.8 poise; the hydroxyl equivalent is 168) (6
-2))

The hydrotalcite compound used in Examples 3 to 5 and Comparative Example 3 is a product name DHT-4A (manufactured by Kyowa Chemical Industry Co., Ltd.), and its general formula is shown below. Mg _4.5 Al ₂ (OH) ₁₃ CO ₃ .3.5H ₂ O The phenol novolak resin used in Example 4 was
The hydroxyl equivalent is 103 and the melt viscosity at 150 ° C. is 2.5 poise.

[0028]

[Table 1]

[0029]

[Table 2]

[0030]

According to the present invention, the use of the resin composition of the present invention is excellent in the filling property of a thin package, and the obtained semiconductor package is excellent in electrical properties in a high-temperature atmosphere, reliability, and solder resistance after moisture absorption. .

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 3/36 C08K 3/36 C08L 63/00 C08L 63/00 CB H01L 23/29 H01L 23/30 R 23/31

Claims (2)

[Claims] (A) an epoxy resin containing the epoxy compound represented by the general formula (1) in an amount of 30% by weight or more in a total epoxy resin, (B) a phenol resin curing agent having a melt viscosity at 150 ° C. of 5 poise or less, (C) a brominated epoxy resin, (D) antimony oxide, (E) at least one inorganic ion exchanger selected from bismuth oxide hydrate and hydrotalcite compounds, (F) fused silica powder, and (G) ) In the epoxy resin composition for semiconductor encapsulation containing a curing accelerator as an essential component, the sum R of the compounding weights of the epoxy resin, the phenol resin curing agent, and the brominated epoxy resin, and the weight a of the bromine atoms in the brominated epoxy resin, The following relationship is established between the weight (b) of antimony atoms in antimony oxide and the weight (c) of the inorganic ion exchanger. Poxy resin composition. 0.2 <a / b <3.0, 0.03 <(a + b) / R ≦
0.2 and 0.05 <c / (a + b) ≦ 3 (Wherein R is hydrogen, an alkyl group having 1 to 9 carbon atoms,
A group selected from halogen atoms, which may be the same or different. ) 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the phenol resin curing agent having a melt viscosity of 5 poise or less at 150 ° C. of the component (B) is represented by the general formula (2). Embedded image (Where m ≧ 0, n ≧ 0, and m + n ≧ 1)