JP2002220434A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition for sealing semiconductors which has excellent mold release characteyistics, continuous moldability and soldering crack resistance. SOLUTION: The composition is characterized by having, as essential components, (A) a phenol aralkyl type epoxy resin containing a diphenylene skeleton of 50-100 wt.% with respect to the all epoxy resins, (B) a phenolic resin containing the skeleton of 50-100 wt.% based on the all phenolic resins, (C) a curing accelerator, (D) an inorganic filler and (E) a glycerol fatty acid triester of glycerol with a 24-36C saturated fatty acid.

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 excellent in mold release properties and continuous moldability, and a semiconductor device excellent in solder crack resistance.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become more sophisticated, lighter, thinner, and smaller, semiconductor devices have been increasingly integrated and surface mounted. Along with this, the demand for epoxy resin compositions for semiconductor encapsulation is becoming increasingly severe. In particular, when a semiconductor device is thinned, cracks may occur in the semiconductor element itself inside the semiconductor device due to the occurrence of stress due to insufficient release between the mold and the cured product of the epoxy resin composition, or the cured product and the semiconductor There is a problem that the adhesion at the interface with the element is reduced. In addition, as solder reflow temperature rises due to deleading of solder caused by environmental problems, solder crack resistance due to explosive stress generated by vaporization of moisture contained in semiconductor devices is greater than before. Is becoming a problem.

For this reason, various proposals have been made to improve the solder crack resistance. For example, an epoxy resin composition using an ethoxy resin represented by the general formula (1) and a phenol resin represented by the general formula (2) has been proposed, and this resin has many hydrophobic structures in its skeleton. The cured product has a low moisture absorption rate, and has a low elasticity in a high temperature range above the glass transition temperature due to a low crosslinking density, and the cured product of the epoxy resin composition has a low water absorption rate. Explosive stress due to moisture vaporization during solder reflow can be reduced, and due to the low elastic modulus during heat, thermal stress generated during solder reflow is reduced, resulting in excellent solder crack resistance. However, this resin is inferior in adhesion to metal members because it contains many hydrophobic parts, and the use of a conventional release agent causes a decrease in solder crack resistance due to a further decrease in adhesion. A. For this reason, there is a demand for the development of a new release agent having excellent releasability without impairing the adhesion between the cured product of the epoxy resin composition and the metal member.

[0004]

The present invention relates to an epoxy resin composition for semiconductor encapsulation using a resin component having low moisture absorption and low stress and a specific release agent, and a semiconductor device using the same.
An object of the present invention is to provide a semiconductor device which is excellent in mold releasability and continuous moldability at the time of molding a semiconductor device and which is excellent in solder crack resistance.

[0005]

Means for Solving the Problems The present invention provides [1] (A)
50 to 100% by weight of the epoxy resin represented by the general formula (1) in the total epoxy resin, and (B) 50 to 100% by weight of the phenol resin represented by the general formula (2)
% By weight, (C) a curing accelerator, (D) an inorganic filler, and (E) glycerin trifatty acid ester of glycerin and a saturated fatty acid having 24 to 36 carbon atoms as essential components. Epoxy resin composition,

Embedded image (R is a group selected from a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and may be the same or different. N is a positive number of 1 to 3 on average)

[0006]

Embedded image (R is a group selected from a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and may be the same or different from each other. N is a positive number of 1 to 3 on average) 2] The epoxy for semiconductor encapsulation according to (1), wherein a glycerin trifatty acid ester of glycerin and a saturated fatty acid having 24 to 36 carbon atoms is contained in the entire epoxy resin composition in an amount of 0.02 to 0.5% by weight. Resin composition, [3] No. (1)
A semiconductor device obtained by sealing a semiconductor element using the epoxy resin composition for semiconductor sealing according to the above item or (2).

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The general formula (1) used in the present invention
The epoxy resin represented by is characterized in that the cured product has a low moisture absorption rate due to the presence of many hydrophobic structures in the resin skeleton, and has a low elastic modulus in the high temperature range above the glass transition temperature due to the low crosslinking density. Having. A cured product of the epoxy resin composition for semiconductor encapsulation using a resin for this purpose exhibits a low water absorption rate, and can reduce explosive stress due to vaporization of water during solder reflow. Further, since the elastic modulus is low at the time of heat, thermal stress generated at the time of solder reflow is small, and as a result, the solder crack resistance is excellent. In order to maximize the characteristics of the epoxy resin represented by the general formula (1) such as a low water absorption, a low elastic modulus, and a low thermal stress, the epoxy resin represented by the general formula (1) is added to the total epoxy resin in an amount of 50% by weight. % Must be included. As other epoxy resins when used together,
For example, phenol novolak type epoxy resin, cresol novolak type epoxy resin, biphenyl type epoxy resin, bisphenol type epoxy resin, stilbene type epoxy resin, triphenolmethane type epoxy resin, phenol aralkyl (including phenylene skeleton) type epoxy resin, naphthol type epoxy resin Resins, alkyl-modified triphenolmethane-type epoxy resins, triazine nucleus-containing epoxy resins, dicyclopentadiene-modified phenol-type epoxy resins, and the like may be used alone or in combination. Specific examples of the epoxy resin represented by the general formula (1) are shown below, but are not limited thereto.

[0008]

Embedded image (N is an average of 1 to 3 positive numbers)

The phenolic resin represented by the general formula (2) used in the present invention contains a lot of hydrophobic structures in the resin skeleton, so that the cured product has a low moisture absorption rate, and has a low cross-linking density. It has the characteristic that the elastic modulus in a high temperature range higher than the temperature is small. Therefore, a cured product of the epoxy resin composition for semiconductor encapsulation using this resin exhibits a low water absorption and can reduce explosive stress due to vaporization of water during solder reflow. Further, since the elastic modulus is low at the time of heat, thermal stress generated at the time of solder reflow is small, and as a result, the solder crack resistance is excellent. In order to maximize the characteristics of the phenolic resin represented by the general formula (2) such as low water absorption, low elastic modulus, and low thermal stress, the phenolic resin represented by the general formula (2) is added to the total phenolic resin in an amount of 50% by weight. % Must be included. Other phenolic resins used in combination include, for example, phenol novolak resin, cresol novolak resin, triphenol methane resin, terpene modified phenol resin, dicyclopentadiene modified phenol resin, phenol aralkyl resin, naphthol aralkyl resin, and the like. They may be used alone or as a mixture. Specific examples of the epoxy resin represented by the general formula (1) are shown below, but are not limited thereto.

[0010]

Embedded image (N is a positive number of 1 to 3 in average) The equivalent ratio of the epoxy group of all epoxy resins used in the present invention to the phenolic hydroxyl group of all phenol resins is as follows:
Preferably it is 0.5-2, especially 0.7-1.5. If the ratio is out of the range of 0.5 to 2, the moisture resistance, the curability and the like are undesirably reduced.

The curing accelerator used in the present invention includes:
A substance that can serve as a catalyst for a crosslinking reaction between an epoxy resin and a phenol resin.
Examples thereof include amine compounds such as diazabicyclo (5,4,0) undecene-7, organic phosphorus compounds such as triphenylphosphine and tetraphenylphosphonium / tetraphenylborate salts, and imidazole compounds such as 2-methylimidazole. It is not limited to these. These curing accelerators may be used alone or as a mixture.

The inorganic filler used in the present invention includes, for example, fused silica, crystalline silica, alumina, silicon nitride, aluminum nitride and the like. When the blending amount of the inorganic filler is particularly increased, it is common to use fused silica. Fused silica can be used in either crushed or spherical form, but in order to increase the blending amount of the fused silica, and to suppress an increase in the melt viscosity of the epoxy resin composition, it is preferable to mainly use a spherical form. . In order to further increase the blending amount of the spherical silica, it is desirable to adjust the particle size distribution of the spherical silica to be wider.

Glycerin used in the present invention and carbon number 2
The glycerin trifatty acid ester with a saturated fatty acid of 4 to 36 has a function of imparting sufficient fluidity to the epoxy resin composition and further improving the releasability. Specific examples include glycerin trilignoserate, glycerin triserotinate, and glycerin trimontanate. These may be used alone or as a mixture. The saturated fatty acid used for the esterification has 23 carbon atoms.
The following is not preferable because sufficient releasability cannot be obtained.
If the number of carbon atoms is 37 or more, the molecular weight is large, so that the fluidity is lowered, or excessive bleeding may cause mold contamination, which is not preferable. For monoester and diester,
It is not preferable because the moisture resistance of the cured product of the epoxy resin composition is reduced due to the influence of the remaining hydroxyl groups, and as a result, the solder crack resistance is adversely affected. In the present invention, the carbon number of the saturated fatty acid refers to the sum of the carbon numbers of the alkyl group and the carboxyl group in the saturated fatty acid.

Glycerin used in the present invention and C2
Other release agents can be used in combination as long as the properties of the glycerin trifatty acid ester with 4-36 saturated fatty acids are not impaired. For example, natural waxes such as carnauba wax,
Examples include synthetic waxes such as polyethylene wax, and metal salts of higher fatty acids such as zinc stearate. The compounding amount of glycerin trifatty acid ester of glycerin and a saturated fatty acid having 24 to 36 carbon atoms is preferably 0.02 to 0.5% by weight in the total epoxy resin composition. 0.0
If it is less than 2% by weight, sufficient releasability cannot be obtained.
If the content exceeds 0.5% by weight, it moves to the interface between the semiconductor element inside the semiconductor device or the lead frame on which the semiconductor element is mounted and the cured product of the epoxy resin composition at the time of molding, so that the adhesion is significantly impaired and the moisture resistance is reduced, As a result, the solder crack resistance is adversely affected. Further, excessive bleeding is not preferable because mold stain is generated.

The epoxy resin composition of the present invention comprises (A)
The component (E) is an essential component. In addition to the above, a coupling agent, a brominated epoxy resin, a flame retardant such as antimony trioxide, a phosphorus compound, a coloring agent such as carbon black, a silicone oil, a silicone rubber, if necessary. Various additives such as a low-stress agent such as synthetic rubber and an antioxidant may be appropriately compounded. The epoxy resin composition of the present invention comprises (A)
(E) After mixing a component and other additives using a mixer etc., it heat-kneads using a heating kneader, a hot roll, an extruder, etc., and then cools and grinds. In order to encapsulate an electronic component such as a semiconductor element using the epoxy resin composition of the present invention and manufacture a semiconductor device, the molding may be performed by a conventional molding method such as a transfer molding, a compression molding, and an injection molding. .

[0016]

The present invention will be specifically described below with reference to examples.
The mixing ratio is by weight. Example 1 8.0 parts by weight of an epoxy resin of the formula (3) (softening point: 58 ° C., epoxy equivalent: 273) 6.0 parts by weight of a phenol resin of the formula (5) (softening point: 67 ° C., hydroxyl equivalent: 203) 1,8 -Diazabicyclo (5,4,0) undecene-7 (hereinafter referred to as DBU) 0.2 parts by weight Spherical fused silica 85.2 parts by weight Glycerin trimontanate (fatty acid having 29 carbon atoms) 0.3 parts by weight carbon black After mixing 0.3 parts by weight using a mixer, the surface temperature was 95 ° C and 2 ° C.
The mixture was kneaded 20 times using a biaxial roll at 5 ° C., and the obtained kneaded material sheet was cooled and pulverized to obtain an epoxy resin composition. The properties of the obtained epoxy resin composition were evaluated by the following methods.

Evaluation method Spiral flow: Using a mold for measuring spiral flow according to EMMI-1-66, a mold temperature of 175 ° C.
It was measured at an injection pressure of 70 kg / cm ² and a curing time of 2 minutes.
The unit is cm. Releasability: Using a transfer molding machine, mold temperature 17
5 ° C., injection pressure 75 kg / cm ² , curing time 2 minutes, 14
4pQFP (20 × 20 × 1.7 mm thickness) was continuously molded 10 times. In these 10 moldings, the number of times of adhesion to the mold at the time of release from the mold or the number of times of cracking or chipping occurring in the cured product was 5 times or more, ×: 1 to 4 times, Δ: No occurrence It was judged as ○. Continuous moldability: Using a transfer molding machine, 144pQFP (20 × 20 × 1.7 mm thickness) was continuously molded at a mold temperature of 175 ° C., an injection pressure of 75 kg / cm ² , and a curing time of 2 minutes. The number of molding shots when molding defects such as cull and chipping of the package occurred are shown. Solder crack resistance: 144 pQFP (20 × 20 × 1.7 mm thickness) using a transfer molding machine at a mold temperature of 175 ° C., an injection pressure of 75 kg / cm ² , and a curing time of 2 minutes.
And then post-cured at 175 ° C. for 8 hours, left in an environment of 85 ° C. and 85% relative humidity for 168 hours, and then
It was immersed in a solder bath at 0 ° C. for 10 seconds. After that, the inside is seen through with an ultrasonic flaw detector, and [(the number of packages in which peeling occurs) / (the number of all packages) × 100]] is obtained.
Those with less than 20% were rated as Δ, and those with 20% or more were rated as x.
n = 10.

Examples 2 to 5, Comparative Examples 1 to 7 The components used in addition to Example 1 are as follows. Biphenyl type epoxy resin (melting point 105 ° C, epoxy equivalent 191), phenol novolak resin (softening point 80 ° C,
Hydroxyl equivalent 105), glycerin triserotinate (carbon number 26), glycerin tristearate (carbon number 18), glycerin tri long chain fatty acid ester (carbon number 37 or more), glycerin monomontanate (carbon number 29) ), Glycerin dimontanate (carbon number 29). According to the formulation in 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 Tables 1 and 2.

[Table 1]

[0019]

[Table 2]

[0020]

Industrial Applicability The epoxy resin composition of the present invention has excellent releasability and solder crack resistance. A semiconductor device having excellent moldability and excellent solder crack resistance can be obtained.

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) H01L 23/29 H01L 23/30 R 23/31 F term (reference) 4J002 CC04X CC05X CC06X CC07X CC08X CD04W CD05W CD06W CD07W CD14W CD17W DE147 DF017 DJ007 DJ017 EH048 EN026 EU116 EU136 EW146 EW176 FD017 FD090 FD130 FD14X FD156 FD168 GQ05 4J036 AF06 AF36 DA05 DC06 DC40 DC46 DD07 FA01 FA03 FA04 FA05 FA10 FB08 GA23 JA07 4M109 AA01 EA02 EB03 EC05 EB09 EC12

Claims (3)

[Claims] (A) 50 to 100% by weight of the epoxy resin represented by the general formula (1) in the total epoxy resin; and (B) 50% by weight of the phenol resin represented by the general formula (2) in the total phenol resin. To 100% by weight, (C) curing accelerator, (D)
Inorganic filler, (E) glycerin and carbon number 24 to 36
An epoxy resin composition for semiconductor encapsulation, comprising a glycerin trifatty acid ester with a saturated fatty acid as an essential component. Embedded image (R is a group selected from a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and may be the same or different. N is a positive number of 1 to 3 on average.) Formula 2 (R is a group selected from a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and may be the same or different. N is a positive number of 1 to 3 on average) 2. The total epoxy resin composition contains 0.02 to 0.5% by weight of a glycerin trifatty acid ester of glycerin and a saturated fatty acid having 24 to 36 carbon atoms.
The epoxy resin composition for semiconductor encapsulation according to the above. 3. A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition for semiconductor encapsulation according to claim 1 or 2.