JP2003292730A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

(57) [Problem] To be excellent in soldering resistance with little peeling in a semiconductor device during soldering after water absorption even with respect to a lead frame oxidized at the time of wire bonding and the like, with few cracks and excellent solder resistance. To provide an epoxy resin composition for semiconductor encapsulation and a semiconductor device. SOLUTION: (A) Epoxy resin, (B) phenolic resin, (C) curing accelerator, (D) inorganic filler and (E)
An epoxy resin composition for semiconductor encapsulation, comprising a compound having a reducing action as an essential component.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition for semiconductor encapsulation having excellent moldability and a semiconductor device using the same.

[0002]

2. Description of the Related Art Transfer molding of an epoxy resin composition is suitable for encapsulating semiconductor elements such as ICs and LSIs at low cost and is suitable for mass production. It has been adopted for a long time, and the epoxy resin and curing agent are also reliable. The properties have been improved by improving the phenol resin. However, in recent market trends of miniaturization, weight reduction, and high performance of electronic equipment, semiconductor elements are becoming highly integrated year by year, and the surface mounting of semiconductor devices is being promoted. The demand for epoxy resin compositions is becoming more and more severe. Therefore, there are some problems that cannot be solved by conventional epoxy resin compositions. The biggest problem is that the semiconductor device is rapidly exposed to a high temperature of 200 ° C. or higher in the solder dipping or solder reflow process due to the use of the surface mounting, and the stress caused when the absorbed water explosively vaporizes the semiconductor element, This is a phenomenon in which peeling occurs at the interface between various plated joints on the lead frame or inner lead and the cured product of the epoxy resin composition, or cracks occur in the semiconductor device, resulting in a marked decrease in reliability.

In order to improve the reliability deterioration due to the soldering treatment, the amount of the inorganic filler in the epoxy resin composition is increased to achieve low water absorption, high strength and low thermal expansion, thereby improving the solder resistance. It is becoming common to use a resin component having a low melt viscosity to improve the fluidity and maintain a low viscosity and a high fluidity during molding. On the other hand, in terms of reliability during soldering, the adhesiveness at the interface between a cured product of an epoxy resin composition and a member such as a semiconductor element or a lead frame existing inside a semiconductor device has become very important. If the adhesive strength at this interface is weak, peeling occurs at the interface with the member after soldering, and further cracking occurs in the semiconductor device due to this peeling, but at the interface between the lead frame and the cured product of the epoxy resin composition. Oxidation of the lead frame at the time of wire bonding is one of the causes of the decrease in the adhesive strength of the.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides less peeling in a semiconductor device during a soldering process after absorbing water even for a lead frame that is oxidized during wire bonding.
The present invention provides an epoxy resin composition for semiconductor encapsulation and a semiconductor device which have few cracks and excellent solder resistance.

[0005]

The present invention provides [1] (A)
An epoxy resin composition for semiconductor encapsulation, which comprises an epoxy resin, (B) a phenol resin, (C) a curing accelerator, (D) an inorganic filler and (E) a compound having a reducing action as essential components, [2] The epoxy resin composition for semiconductor encapsulation according to the item [1], wherein the compound (E) having a reducing action is an aromatic hydroxy compound and the compound is used alone or in combination of two or more. ] A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition according to the items [1] and [2].

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The epoxy resin used in the present invention is a monomer, oligomer or polymer having an epoxy group in the molecule, and examples thereof include bisphenol A type epoxy resin, phenol novolac type epoxy resin, orthocresol novolac type epoxy resin, Naphthol novolac type epoxy resin, phenol aralkyl type epoxy resin, dicyclopentadiene modified phenol type epoxy resin, biphenyl type epoxy resin, stilbene type epoxy resin, triphenolmethane type epoxy resin, alkyl modified triphenolmethane type epoxy resin, and triazine nucleus Examples thereof include epoxy resins, and these may be used alone or in combination. Among these epoxy resins, the epoxy resin represented by the general formula (1) has a feature that the elastic modulus at the solder reflow temperature is low because the distance between the cross-linking points of the cured product becomes long, and the stress generated by this Is low and the adhesion is excellent, so that the solder reflow resistance is good, which is preferable.

[Chemical 1] (P is an average value and is an integer of 1 to 5)

The phenol resin used in the present invention is a monomer, oligomer or polymer having a phenolic hydroxyl group in the molecule, and examples thereof include phenol novolac resin, cresol novolac resin, phenol aralkyl resin, terpene modified phenol resin and dicyclopentadiene modified resin. Phenol resin, bisphenol A, triphenol methane and the like can be mentioned, and these may be used alone or in combination. Among these phenolic resins, the epoxy resin represented by the general formula (2) has a characteristic that the elastic modulus at the solder reflow temperature is low because the distance between the cross-linking points of the cured product becomes long, and the stress generated by this Is low and the adhesion is excellent, so that the solder reflow resistance is good, which is preferable.

[Chemical 2] (P is an average value and is an integer of 1 to 5)

As the curing accelerator used in the present invention,
Any material that accelerates the curing reaction between the epoxy group and the phenolic hydroxyl group may be used, and those generally used for sealing materials may be widely used. Examples thereof include amine compounds such as 1,8-diazabicyclo (5,4,0) undecene-7, imidazole compounds such as 2-methylimidazole, and organic phosphorus compounds such as triphenylphosphine. These may be used alone or as a mixture. You may use it.

The kind of the inorganic filler used in the present invention is not particularly limited, but those generally used for the sealing material can be used. For example, fused crushed silica, fused spherical silica, crystalline silica, secondary agglomerated silica,
Alumina, titanium white, aluminum hydroxide and the like can be mentioned, and fused spherical silica is particularly preferable. It is preferable that the shape is infinitely spherical, and the filling amount can be increased by mixing particles having different particle sizes. The content of the inorganic filler in the total epoxy resin composition is preferably 65 to 94% by weight, more preferably 75 to 92% by weight. If it is less than the lower limit, the reinforcing effect by the inorganic filler is not sufficiently expressed, and the amount of the resin component that is a water absorption factor increases, so that the water absorption of the cured product of the epoxy resin composition increases. However, cracks may easily occur in the semiconductor device during soldering. If the upper limit is exceeded, the fluidity of the epoxy resin composition will decrease, and filling defects, chip shifts, pad shifts, and wire sweeps may occur during molding.

The compound having a reducing action used in the present invention is hydroxybenzene, hydroquinone, catechol,
It is an aromatic hydroxy compound such as pyrogallol, hydroxyhydroquinone and o-aminophenol, and it is preferable to use one kind or a combination of two or more kinds of these compounds. Since these reducing agents can reduce the oxide on the surface of the metal such as the lead frame, the addition of these reducing agents to the epoxy resin composition improves the adhesive strength between the lead frame and the epoxy resin composition. Can be made. The compounding amount of the compound having a reducing action is preferably 0.005 to 3% by weight, and more preferably 0.01 to 1% by weight in the total epoxy resin composition. If it is less than the lower limit, the effect of addition is weak, which is not preferable. On the other hand, if the amount exceeds the upper limit, unreacted compound having a reducing action remains at the interface and alienates the adhesion, which is not preferable. Further, these compounds having a reducing action may be preliminarily heated and mixed with all or part of the epoxy resin or the phenol resin.

The epoxy resin composition of the present invention comprises (A)-
In addition to the component (D), if necessary, brominated epoxy resin, antimony oxide, phosphorus compound, flame retardants such as magnesium hydroxide, aluminum hydroxide and boric acid compound, inorganic ion exchanger such as bismuth oxide hydrate, Coupling agents such as γ-glycidoxypropyltrimethoxysilane and γ-aminopropyltriethoxysilane, colorants such as carbon black and red iron oxide, low stress components such as silicone oil and silicone rubber, natural wax, synthetic wax, Various additives such as a higher fatty acid and a metal salt thereof or a release agent such as paraffin may be blended.

The epoxy resin composition of the present invention comprises (A)-
It can be obtained by a general method in which the component (D) and other additives are mixed at room temperature using a mixer or the like, melt-kneaded with a kneader such as a roll, kneader, or extruder, cooled, and then pulverized. In order to manufacture a semiconductor device by sealing an electronic component such as a semiconductor element using the epoxy resin composition of the present invention, molding and curing may be performed by a molding method such as a transfer mold, a compression mold or an injection mold.

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples.   Example 1   Epoxy resin containing formula (3) as a main component (manufactured by Japan Epoxy Resin Co., Ltd., Y X-4000, epoxy equivalent 195, melting point 105 ° C)                                                             6.2 parts by weight

[Chemical 3]

[0014]   Formula (4) phenol resin (Mitsui Chemicals, Inc., XLC-LL, hydroxyl equivalent 1 74, softening point 75 ° C) 5.7 parts by weight

[Chemical 4]

Hydroxybenzene 0.1 part by weight γ-glycidylpropyltrimethoxysilane 0.3 part by weight Fused spherical silica (average particle size 30 μm) 87.0 parts by weight 1,8-diazabicyclo (5,4,0) undecene- 7 (hereinafter referred to as DBU) 0.2 parts by weight carbon black 0.2 parts by weight carnauba wax 0.3 parts by weight After mixing all of the above components using a mixer, two surface temperatures of 90 ° C. and 45 ° C. The mixture was kneaded using a roll, cooled, and then pulverized to obtain an epoxy resin composition. The obtained epoxy resin composition was evaluated by the following methods.

Evaluation method Spiral flow: A spiral flow measuring mold according to EMMI-1-66 was used, and the mold temperature was 175 ° C., the injection pressure was 6.9 MPa, and the curing time was 120 seconds. Heat strength: Using a low pressure transfer molding machine, a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, a curing time of 120 seconds, and a test piece (length 80 mm, width 10 mm, thickness 4 mm).
And after post-curing at 175 ° C. for 8 hours, 26
The bending strength at 0 ° C was measured according to JIS K 6911. The unit is N / mm ² . Adhesion: Using a low-pressure transfer molding machine, a mold temperature of 175 ° C., an injection pressure of 9.8 MPa, a curing time of 120 seconds, an epoxy resin composition, and a molded article (2 × (2 × 2 mm) was integrally molded so as to be in close contact, and a force was applied in the direction of the arrow as shown in FIG. 1 to measure the shear strength. The measurement temperature is 260 ° C, and the unit is MPa.
The adherend is a copper material plated with copper flash,
Furthermore, this copper flash-plated product was heated on a hot plate at 260 ° C for 20 seconds to be in the same oxidation state as that after wire bonding, and the copper material was flash-plated with copper and then silver-plated. Three types of the applied ones were used. Solder resistance: Using a low-pressure transfer molding machine, mold temperature 175 ° C., injection pressure 8.3 MPa, curing time 120 seconds, 160-pin LQFP (package size 24 × 2
4 mm, thickness 1.4 mm, silicon chip size is 7.
0x7.0mm, the lead frame is the same as that after wire bonding after heating the copper material with copper flash plating and the copper material with copper flash plating on a hot plate at 260 ° C for 20 seconds. (2 types of those in the oxidized state) were molded and post-cured at 175 ° C. for 8 hours. The resulting 10 packages were humidified in an environment of 85 ° C. and 60% relative humidity for 168 hours, and in a environment of 85 ° C. and 85% relative humidity for 72 hours in a solder bath at 260 ° C. It was soaked for 10 seconds. External cracks were observed with a microscope, and the crack occurrence rate [(crack occurrence rate) = (number of cracked packages) / (total number of packages) × 100] was expressed in%. Further, the ratio of the peeled area between the chip and the cured product of the epoxy resin composition was measured using an ultrasonic flaw detector, and the peeled rate [(peeled rate) = (peeled area) / (chip area) × 100] was calculated as%. Displayed in.

Examples 2 to 12 and Comparative Examples 1 to 6 According to the formulations shown in Tables 1 and 2, epoxy resin compositions were obtained in the same manner as in Example 1 and evaluated in the same manner as in Example 1.
The results are shown in Tables 1 and 2. The components other than those used in Example 1 are shown below.

An epoxy resin of the formula (1) (epoxy equivalent 2
72, softening point 58 ° C)

[Chemical 5]

Orthocresol novolac type epoxy resin (epoxy equivalent 196, softening point 55 ° C.)

Phenolic resin of formula (2) (hydroxyl equivalent 2
00, softening point 65 ° C),

[Chemical 6]

Phenol novolac resin (hydroxyl equivalent 1
05, softening point 105 ° C.) Hydroquinone catechol molten mixture A: 5.7 parts by weight of the phenol aralkyl resin of the formula (2) was completely melted at 110 ° C., and then hydroxybenzene, a compound having a reducing action, was added to 0.1 wt. A part by weight was added to obtain a molten mixture A. Triphenylphosphine

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

EFFECT OF THE INVENTION The epoxy resin composition of the present invention has less soldering resistance even in a lead frame that is oxidized during wire bonding, and is less likely to peel off in a semiconductor device during soldering treatment after absorbing water and has less cracks. It has excellent characteristics and contributes to improving the reliability of a semiconductor device using the same.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a shear strength measurement molded product in which an adherend and an epoxy resin composition are integrally molded.

[Explanation of symbols]

1 molded product 2 Adherend

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 23/31 F term (reference) 4J002 CC04X CC05X CC07X CC12X CD04W CD05W CD06W CD13W CD20W DE137 DE147 DJ017 EJ028 EJ038 EU116 EU206 EW136 FD017 FD156 FD208 GQ05 4J036 AA01 AC02 AC18 AD07 AF06 AF27 AJ07 DB05 DC46 DD07 FA05 FA06 FB07 JA07 4M109 AA01 CA21 EA02 EB18 EC05

Claims (3)

[Claims] 1. (A) Epoxy resin, (B) Phenolic resin, (C) Curing accelerator, (D) Inorganic filler and (E)
An epoxy resin composition for semiconductor encapsulation, which comprises a compound having a reducing action as an essential component. 2. The epoxy resin composition for semiconductor encapsulation according to claim 1, wherein the compound (E) having a reducing action is an aromatic hydroxy compound, and the compound is used alone or in combination of two or more kinds. 3. A semiconductor device obtained by encapsulating a semiconductor element with the epoxy resin composition according to claim 1.