JP2005281584A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy resin composition excellent in moldability, adhesion to a substrate, flame retardancy, and soldering resistance, without using a bromine-containing organic compound, nor an antimony compound. <P>SOLUTION: This epoxy resin composition contains a phenol aralkyl-type epoxy resin having biphenyl skeletons, a phenol aralkyl resin having the biphenyl skeletons, a curing accelerator, an inorganic filler, a specified silane coupling agent having such a sulfide bond in its molecule that four sulfur atoms are coupled with each other to form the sulfide bond, and a specified silane coupling agent having a mercapto group as essential components. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an epoxy resin composition for semiconductor encapsulation and a semiconductor device using the same.

  As a sealing method for semiconductor elements such as IC and LSI, transfer molding of an epoxy resin composition is suitable for mass production at low cost and has been adopted for a long time, and a phenol resin that is an epoxy resin or a curing agent in terms of reliability. Improvements have been made to improve the characteristics. However, due to the recent trend toward smaller, lighter, and higher performance electronic devices, semiconductors have been increasingly integrated and the surface mounting of semiconductor devices has been promoted. The demand for compositions has become increasingly severe. For this reason, the problem which cannot be solved with the conventional epoxy resin composition has also come out.

  Usually, an epoxy resin composition contains a bromine-containing organic compound and an antimony compound such as antimony trioxide and antimony tetroxide in order to impart flame retardancy, which is not preferable from the viewpoint of environment and hygiene. . Therefore, there is a technique of using a resin having a large number of aromatic rings in the structure as an epoxy resin composition excellent in flame retardancy without using a bromine-containing organic compound and an antimony compound (see, for example, Patent Document 1). . However, since it has a large number of aromatic rings, there is a drawback that the viscosity increases.

  In addition, when mounting a semiconductor device on a printed circuit board, lead-containing solder (tin-lead alloy) has been used. Similarly, lead-containing solder (tin-lead) It is desired not to use an alloy. The melting point of lead-containing solder (tin-lead alloy) is 183 ° C., and the soldering temperature during mounting is 220-240 ° C., whereas in the case of solder not containing lead typified by tin-silver alloy The melting point is high, and the temperature during soldering is about 260 ° C. Therefore, the stress applied to the semiconductor device by the solder dipping or solder reflow process increases, and various plated joint portions such as gold plating and silver plating on the semiconductor device, particularly the semiconductor element, the lead frame, and the inner lead, and the epoxy resin composition Separation occurs at the interface of the cured product, resulting in a significant decrease in reliability.

  In order to improve reliability degradation due to solder processing, increase the amount of inorganic filler in the epoxy resin composition to achieve low moisture absorption, high strength, low thermal expansion, improve solder resistance, There is a technique in which a low melt viscosity resin is used to maintain a high fluidity with a low viscosity during molding (see, for example, Patent Document 2). Although solder resistance is considerably improved by using this method, there is a drawback that fluidity is sacrificed and voids are easily generated in the package as the filling ratio of the inorganic filler increases. In view of this, there has been proposed a technique of adding various coupling agents such as aminosilane to achieve both fluidity and solder resistance (for example, see Patent Document 3), but silver plating of copper lead frames and 42 alloy lead frames. Peeling at the interface between various plated joint parts such as gold plating parts of PPF (palladium preplating) lead frames and the cured product of the epoxy resin composition is not suppressed, and has sufficiently good solder resistance An epoxy resin composition for semiconductor encapsulation was not obtained.

JP-A-11-140277 (pages 2 to 11) JP-A 64-65116 (pages 2 to 7) JP-A-2-218735 (pages 1-9)

  The present invention provides an epoxy resin composition for semiconductor encapsulation excellent in moldability and solder resistance when a PPF frame (palladium pre-plating lead frame) is used, and a semiconductor device using the same. .

The present invention
[1] (A) epoxy resin represented by general formula (1), (B) phenol resin represented by general formula (2), (C) curing accelerator, (D) inorganic filler, (E) An epoxy resin composition for encapsulating a semiconductor, characterized in that the silane coupling agent represented by the general formula (3) and the silane coupling agent represented by (F) the general formula (4) are essential components;

（式中、Ｒ１、Ｒ２は水素又は炭素数１〜４のアルキル基で、互いに同一でも異なっていてもよい。ａは０〜３の整数、ｂは０〜４の整数。ｎは平均値で、１〜５の正数）

(In the formula, R1 and R2 are hydrogen or an alkyl group having 1 to 4 carbon atoms, and may be the same or different. A is an integer of 0 to 3, b is an integer of 0 to 4. n is an average value. , 1-5 positive numbers)

（式中、Ｒ１、Ｒ２は水素又は炭素数１〜４のアルキル基で、互いに同一でも異なっていてもよい。ａは０〜３の整数、ｂは０〜４の整数。ｎは平均値で、１〜５の正数）

(In the formula, R1 and R2 are hydrogen or an alkyl group having 1 to 4 carbon atoms, and may be the same or different. A is an integer of 0 to 3, b is an integer of 0 to 4. n is an average value. , 1-5 positive numbers)

（式中、Ｒ３は炭素数１〜１０のアルコキシ基で、Ｒ４は炭素数１〜１０のアルキル基である。ｎは１〜３の整数）

(In the formula, R3 is an alkoxy group having 1 to 10 carbon atoms, R4 is an alkyl group having 1 to 10 carbon atoms, and n is an integer of 1 to 3).

（式中、Ｒ５は炭素数１〜１２の二価の有機基、Ｒ６、Ｒ７は炭素数１〜１２の一価の炭化水素基、ｎは１〜３の整数）
［２］第［１］に記載の半導体封止用エポキシ樹脂組成物を用いて半導体素子を封止してなることを特徴とする半導体装置、
である。

(In the formula, R5 is a divalent organic group having 1 to 12 carbon atoms, R6 and R7 are monovalent hydrocarbon groups having 1 to 12 carbon atoms, and n is an integer of 1 to 3).
[2] A semiconductor device obtained by sealing a semiconductor element using the epoxy resin composition for semiconductor encapsulation according to [1],
It is.

  According to the present invention, an epoxy resin composition having good flame retardancy without using a bromine-containing organic compound or antimony compound and having good moldability and good adhesion to a PPF frame is obtained. If is used, a semiconductor device having excellent solder resistance can be obtained.

The present invention relates to a phenol aralkyl type epoxy resin having a biphenyl skeleton, a phenol aralkyl resin having a biphenyl skeleton, a curing accelerator, an inorganic filler, and a specific silane coupling agent having a sulfide bond in which four sulfur atoms are bonded in the molecule. And a specific silane coupling agent having a mercapto group as an essential component, an epoxy resin for semiconductor encapsulation having excellent moldability and solder resistance when using a PPF frame (palladium preplating lead frame) A composition is obtained.
Hereinafter, the present invention will be described in detail.

The epoxy resin represented by the general formula (1) used in the present invention has a hydrophobic and rigid biphenylene skeleton between epoxy groups, and a cured product of an epoxy resin composition using the epoxy resin has a moisture absorption rate. It has a low elastic modulus in a high temperature range exceeding the glass transition temperature (hereinafter referred to as Tg), and is excellent in adhesion to a semiconductor element, an organic substrate, and a metal substrate. Moreover, it has the characteristic that heat resistance is high although a crosslinking density is low.
N in the general formula (1) is an average value and is a positive number of 1 to 5, preferably 1 to 3. When n is less than the lower limit, the curability of the epoxy resin composition may be lowered. When n exceeds the upper limit, the viscosity increases and the fluidity of the epoxy resin composition may be reduced. The epoxy resin represented by General formula (1) may be used individually by 1 type, or may use 2 or more types together.
Among the epoxy resins represented by the general formula (1), the epoxy resin represented by the formula (5) is particularly preferable.

You may use another epoxy resin together in the range which does not impair the original characteristic of the epoxy resin represented by General formula (1). When used in combination, it is desirable to use monomers, oligomers, and polymers having an epoxy group in the molecule as low as possible in general. For example, phenol novolac type epoxy resins, cresol novolac type epoxy resins, biphenyl type epoxy resins Bisphenol type epoxy resin, stilbene type epoxy resin, triphenolmethane type epoxy resin, phenol aralkyl type epoxy resin (having phenylene skeleton), naphthol type epoxy resin, naphthalene type epoxy resin, alkyl-modified triphenolmethane type epoxy resin, triazine Examples thereof include a nucleus-containing epoxy resin and a dicyclopentadiene-modified phenol type epoxy resin, and these may be used alone or in combination of two or more.
The amount of the epoxy resin represented by the general formula (1) is preferably 30% by weight or more, and particularly preferably 50% by weight or more in the total epoxy resin. Below the lower limit, the flame retardancy may be insufficient.

The phenol resin represented by the general formula (2) used in the present invention has a hydrophobic and rigid biphenylene skeleton between phenolic hydroxyl groups, and a cured product of an epoxy resin composition using the phenol resin has a moisture absorption rate. The elastic modulus is low in a high temperature range exceeding Tg, and the adhesiveness with a semiconductor element, an organic substrate, and a metal substrate is excellent. Moreover, it has the characteristic that heat resistance is high although a crosslinking density is low.
In the general formula (2), n is an average value and is a positive number of 1 to 5, preferably 1 to 3. When n is less than the lower limit, the curability of the epoxy resin composition may be lowered. When n exceeds the upper limit, the viscosity becomes high and the fluidity of the epoxy resin composition may be lowered. The phenol resin represented by General formula (2) may be used individually by 1 type, or may use 2 or more types together.
Among the phenol resins represented by the general formula (2), the phenol resin represented by the formula (6) is particularly preferable.

You may use together other phenol resin in the range which does not impair the characteristic of the phenol resin represented by General formula (2) used by this invention. When used in combination, it is desirable to use monomers, oligomers, and polymers having a phenolic hydroxyl group in the molecule, and those having a low viscosity as much as possible. For example, phenol novolak resins, cresol novolak resins, phenol aralkyl resins (phenylene skeletons) Naphthol aralkyl resin, triphenol methane resin, terpene-modified phenol resin, dicyclopentadiene-modified phenol resin, and the like. These may be used alone or in combination of two or more.
The use amount of the phenol resin represented by the general formula (2) is preferably 30% by weight or more, and particularly preferably 50% by weight or more in the total phenol resin. Below the lower limit, the flame retardancy may be insufficient.
The equivalent ratio of the epoxy groups of all epoxy resins to the phenolic hydroxyl groups of all phenol resins is preferably 0.5 to 2, and more preferably 0.7 to 1.5. If it is out of the above range, moisture resistance, curability and the like may be lowered.

  The curing accelerator used in the present invention is not particularly limited as long as it accelerates the reaction between an epoxy group and a phenolic hydroxyl group. For example, 1,8-diazabicyclo (5,4,0) undecene-7 is used. Diazabicycloalkene and its derivatives, amine compounds such as tributylamine and benzyldimethylamine, imidazole compounds such as 2-methylimidazole, organic phosphines such as triphenylphosphine and methyldiphenylphosphine, tetraphenylphosphonium tetraphenylborate, Tetraphenylphosphonium ・ tetrabenzoic acid borate, tetraphenylphosphonium ・ tetranaphthoic acid borate, tetraphenylphosphonium ・ tetranaphthoyloxyborate, tetraphenylphosphonium ・ tetranaphthyloxy Tetra-substituted phosphonium tetra-substituted borate borate, and the like. These may be used in combination of two or more be used one kind alone.

  Although it does not specifically limit about the kind of inorganic filler used by this invention, For example, fused crushed silica, fused spherical silica, crystalline silica, secondary agglomerated silica, alumina, titanium white, aluminum hydroxide, magnesium hydroxide, zinc borate, Examples thereof include zinc molybdate, and fused spherical silica is particularly preferable. The shape of the fused spherical silica is preferably infinitely spherical to improve fluidity and has a broad particle size distribution.

  Although it does not prescribe | regulate especially as content of an inorganic filler, 84 weight% or more and 94 weight% or less are preferable in all the epoxy resin compositions. If the lower limit is not reached, the low hygroscopicity of the cured product of the epoxy resin composition may not be obtained and solder resistance may be insufficient. On the other hand, if the upper limit is exceeded, the fluidity of the epoxy resin composition may decrease, resulting in poor filling during molding, or inconveniences such as deformation of the gold wire in the semiconductor device due to increased viscosity.

The present invention achieves flame retardancy without using bromine-containing organic compounds and antimony compounds. The bromine atom and antimony atom in the total epoxy resin composition in the present invention are each 0.05% by weight or less. This means that for economic reasons, bromine atoms and antimony atoms are not added in addition to the trace amounts of components mixed in the raw materials and the manufacturing stage.
The inorganic filler used in the present invention is preferably mixed well in advance. In addition, if necessary, the inorganic filler may be pre-coated with a coupling agent, an epoxy resin or a phenol resin, and the coating method may be a method of removing the solvent after mixing with a solvent or directly. Examples of the method include adding to an inorganic filler and mixing using a mixer.

The silane coupling agent represented by the general formula (3) used in the present invention is essential. When the silane coupling agent represented by the general formula (3) is added, since the adhesion after post-curing is excellent while suppressing the adhesion immediately after molding, the molded product runner is removed from the lead frame after molding. A resin composition having features such as excellent workability and good solder resistance can be obtained. The silane coupling agent represented by the general formula (3) may be used alone or in combination of two or more. Moreover, although a compounding quantity is not specifically limited, 0.01 to 1 weight% is desirable in all the epoxy resin compositions, More preferably, it is 0.05 to 0.5 weight%. If the lower limit is not reached, sufficient moldability may not be obtained, and if the upper limit is exceeded, curability may be reduced.

The silane coupling agent represented by the general formula (4) used in the present invention is essential. Since the silane coupling agent represented by the general formula (4) has a mercapto group in the molecule, a resin composition having excellent adhesion to the lead frame can be obtained by adding this. The silane coupling agent represented by General formula (4) may be used individually by 1 type, or may use 2 or more types together. Moreover, although a compounding quantity is not specifically limited, 0.01 to 1 weight% is desirable in all the epoxy resin compositions, More preferably, it is 0.05 to 0.5 weight%. If the lower limit is not reached, sufficient adhesion may not be obtained, and if it exceeds the upper limit, curability may be lowered.

  In the present invention, it is essential to use the silane coupling agent represented by the general formula (3) and the silane coupling agent represented by the general formula (4) in combination, Moldability and solder resistance are not sufficient. Specifically, only the silane coupling agent represented by the general formula (3) does not provide sufficient adhesion after post-curing of the molded product, and solder resistance is poor. On the other hand, with the silane coupling agent represented by the general formula (4), the adhesion immediately after molding is too high and the runner of the molded product cannot be peeled off from the lead frame at the time of gate break. There is a risk of frame deformation and abnormal formability.

  The epoxy resin composition of the present invention has components A to F as essential components, but if necessary, other than the epoxy silane, amino silane, alkyl silane, represented by general formula (3) and general formula (4), Silane coupling agents such as ureido silane and vinyl silane, titanate coupling agents, aluminum coupling agents, coupling agents such as aluminum / zirconium coupling agents, colorants such as carbon black and bengara, natural waxes such as carnauba wax, Synthetic waxes such as polyethylene wax, higher fatty acids such as stearic acid and zinc stearate and release agents such as metal salts or paraffin thereof, silicone oil, low stress additives such as silicone rubber, aluminum hydroxide, magnesium hydroxide, boric acid Flame retardants such as zinc and zinc molybdate, Mass hydrate inorganic ion exchangers such like, no problem be properly compounded with various additives.

The epoxy resin composition of the present invention can be obtained by mixing the raw materials sufficiently uniformly using a mixer or the like, then melt-kneading with a hot roll or a kneader, cooling and pulverizing.
The epoxy resin composition of the present invention is used to encapsulate various electronic components such as semiconductor elements, and to manufacture semiconductor devices by conventional molding methods such as transfer molding, compression molding, and injection molding. do it.

Examples of the present invention are shown below, but the present invention is not limited thereto. The blending ratio is parts by weight.
Example 1
Epoxy resin 1: epoxy resin represented by formula (5) (Nippon Kayaku Co., Ltd., NC3000, softening point 58 ° C., epoxy equivalent 273) 66 parts by weight

Phenol resin 1: phenol resin represented by formula (6) (Maywa Kasei Co., Ltd., MEH-7851SS, softening point 107 ° C., hydroxyl group equivalent 204) 48 parts by weight

1,8-diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU)
5 parts by weight Fused spherical silica (average particle size 21 μm) 870 parts by weight Coupling agent 1: Coupling agent represented by formula (7) (manufactured by Shin-Etsu Chemical Co., Ltd., KBE-849) 1 part by weight

カーボンブラック ３重量部
カルナバワックス ５重量部
をミキサーにて混合し、熱ロールを用いて、９５℃で８分間混練して冷却後粉砕し、エポキシ樹脂組成物を得た。得られたエポキシ樹脂組成物を、以下の方法で評価した。結果を表１に示す。 Coupling agent 2: Coupling agent represented by formula (8) (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-803) 2 parts by weight

Carbon black 3 parts by weight Carnauba wax 5 parts by weight were mixed with a mixer, kneaded at 95 ° C. for 8 minutes using a hot roll, cooled and pulverized to obtain an epoxy resin composition. The obtained epoxy resin composition was evaluated by the following methods. The results are shown in Table 1.

Evaluation method Spiral flow: Using a spiral flow measurement mold according to EMMI-1-66, measurement was performed at a mold temperature of 175 ° C., a pressure of 6.9 MPa, and a curing time of 120 seconds. The unit is cm.
Adhesiveness: Using a transfer molding machine, a 2 mm × 2 mm × 2 mm adhesion strength test piece was molded on a lead frame under conditions of a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, and a curing time of 120 seconds. The lead frame used was a NiPd alloy frame plated with gold. The result measured immediately after molding was adhesiveness 1, and the result measured after post-curing at 175 ° C. for 8 hours was defined as adhesiveness 2. For the measurement, the shear strength between the cured product of the epoxy resin composition and the frame was measured using an automatic shear strength measuring device (PC2400, manufactured by DAGE). The unit is MPa.
Gate breakability: Molding of 80pQFP (NiPd alloy frame gold-plated, chip size 6.0mm x 6.0mm) using a low-pressure transfer molding machine at a molding temperature of 175 ° C, a pressure of 8.3MPa, and a curing time of 120 seconds. After that, when the frame and the molded product runner were peeled off, those that were cleanly peeled off were OK, and those that had runner breakage or frame deformation were judged as NG.
Solder resistance: Molding of 80pQFP (NiPd alloy frame gold-plated, chip size 6.0mm x 6.0mm) at a molding temperature of 175 ° C, a pressure of 8.3MPa, and a curing time of 120 seconds using a low-pressure transfer molding machine. Then, after heat treatment at 175 ° C. for 8 hours as an after bake, a humidification treatment was performed at 85 ° C. and a relative humidity of 60% for 168 hours, followed by IR reflow treatment at 260 ° C. three times. Peeling and cracks inside the package were confirmed with an ultrasonic flaw detector. The number of defective packages among the 10 packages is shown.
Flame retardancy: Using a transfer molding machine, a molded product having a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, a curing time of 120 seconds, a length of 127 mm, a width of 12.7 mm, and a thickness of 1.6 mm is molded. After curing as a cure at 175 ° C. for 8 hours, the obtained molded product was humidified for 48 hours in an environment of 23 ° C. and a relative humidity of 50%, and a flame retardancy test was performed according to UL-94.

Examples 2-9, Comparative Examples 1-5
According to the composition of Table 1, an epoxy resin composition was obtained in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 1.
The raw materials used other than Example 1 are shown below.
Epoxy resin 2: Epoxy resin mainly composed of formula (9) (manufactured by Japan Epoxy Resin Co., Ltd., YX-4000, epoxy equivalent 190 g / eq, melting point 105 ° C.)

Phenol resin 2: Phenol resin represented by formula (10) (Mitsui Chemicals, XLC-LL, hydroxyl group equivalent 165 g / eq, softening point 79 ° C.)

Coupling agent 3: Coupling agent represented by the formula (11) (manufactured by Shin-Etsu Chemical Co., Ltd., KBM-403)

  Comparing Example 1 with Comparative Examples 1 and 2, it can be seen that the gate breakability and solder resistance are improved by using the coupling agents 1 and 2 in combination rather than individually. The effect does not appear when coupling agent 1 and coupling agent 3 or coupling agent 2 and coupling agent 3 are used in combination as in Comparative Examples 3 and 4, and other resins as in Comparative Example 7 It is a peculiar thing that does not appear even when using.

  According to the present invention, an epoxy resin composition having good flame retardancy without using a bromine-containing organic compound or antimony compound and having good moldability and good adhesion to a PPF frame is obtained. Since a semiconductor device in which a semiconductor element is sealed using a metal has excellent solder resistance, it is suitable for a surface mounting semiconductor device, particularly a semiconductor device using a gold-plated lead frame and an inner lead. It can be used suitably.

Claims (2)

(A) epoxy resin represented by general formula (1), (B) phenol resin represented by general formula (2), (C) curing accelerator, (D) inorganic filler, (E) general formula ( 3. An epoxy resin composition for encapsulating a semiconductor, comprising as essential components a silane coupling agent represented by 3) and a silane coupling agent represented by (F) general formula (4).

(In the formula, R1 and R2 are hydrogen or an alkyl group having 1 to 4 carbon atoms, and may be the same or different. A is an integer of 0 to 3, b is an integer of 0 to 4. n is an average value. , 1-5 positive numbers)

(In the formula, R1 and R2 are hydrogen or an alkyl group having 1 to 4 carbon atoms, and may be the same or different. A is an integer of 0 to 3, b is an integer of 0 to 4. n is an average value. , 1-5 positive numbers)

(In the formula, R3 is an alkoxy group having 1 to 10 carbon atoms, R4 is an alkyl group having 1 to 10 carbon atoms, and n is an integer of 1 to 3).

(In the formula, R5 is a divalent organic group having 1 to 12 carbon atoms, R6 and R7 are monovalent hydrocarbon groups having 1 to 12 carbon atoms, and n is an integer of 1 to 3). A semiconductor device obtained by sealing a semiconductor element using the epoxy resin composition for semiconductor sealing according to claim 1.