JP2001270932A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an epoxy resin composition which can reduce the warpage of a semiconductor package (e.g. a BGA) and can enhance the reflow resistance and a semiconductor device sealed with the same. SOLUTION: This epoxy resin composition contains an epoxy resin represented by formula (1) (wherein n is 0-5), a phenol novolak resin represented by formula (2) (wherein m is 0-10, and when m is 0, then the compound is dinuclear) and having a content of dinuclear compound of 10 wt.% or lower, an inorganic filler, and a cure accelerator.

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 used for encapsulating a semiconductor, and a semiconductor device encapsulated with the epoxy resin composition.

[0002]

2. Description of the Related Art In recent years, the size and thickness of semiconductor packages have been rapidly reduced, and the number of terminals of a peripheral terminal type package represented by a SOP or QFP as a surface mount type package has been increasing.
It is reaching practical limits. Under such circumstances, a ball terminal type package represented by BGA has been newly developed,
It has become the mainstream of IC and LSI chip packages.

There are various types of BGAs depending on a chip connection method and the like. Among these, those mainly manufactured adopt a wire bonding method as a chip connection method. For example, this BGA
Is to mount the chip on one side of the package substrate, connect the chip to the conductor pattern on the package substrate with a thin gold wire, etc., and then seal only the chip mounting surface with epoxy resin composition etc. by transfer molding method It is formed by molding and sealing with a material and by providing a solder ball on an electrode pad located on the surface opposite to the chip mounting surface.

However, in such a BGA package, a sealing material having a different linear expansion coefficient (α1) and a package substrate are bonded on one side, so that the sealing material is cooled immediately after molding to room temperature. There has been a problem that an imbalance in the shrinkage rate occurs on the bonding surface between the material and the package substrate, and the package warps.

[0005] Further, when the adhesion between the encapsulant and the package substrate is low, when the package is mounted on the mounting substrate by reflow soldering, cracks occur in the package, and reliability such as reflow resistance is low. The property was reduced.

[0006]

Attempts have been made to use an epoxy resin composition containing a triphenolmethane-type epoxy resin as a main component as a sealing material.
When this is used, the glass transition temperature (Tg) of the sealing material becomes higher than the molding temperature, and when cooled to room temperature immediately after molding, the shrinkage ratio between the sealing material and the package substrate becomes almost the same, The package is less likely to warp.

However, this method can reduce the warpage of the package, but cannot improve the adhesion between the sealing material and the package substrate, and the reflow resistance of the package is at a satisfactory level. Thus, both the problems of warpage and reflow resistance cannot be solved.

The present invention has been made in view of the above points, and has been made of an epoxy resin composition capable of reducing warpage of a semiconductor package such as BGA and improving reflow resistance.
It is another object of the present invention to provide a semiconductor device sealed using the epoxy resin composition.

[0009]

The epoxy resin composition according to claim 1 of the present invention has an epoxy resin represented by the following formula (1) and a binuclear body having a content of 10% by mass or less. It comprises a phenol novolak resin, an inorganic filler, and a curing accelerator.

[0010]

Embedded image

[0011] The invention of claim 2 is characterized in that, in claim 1, it comprises a silicone rubber powder whose surface is coated with a silicone resin.

The invention of claim 3 is characterized in that, in claim 1 or 2, the curing accelerator is an imidazole.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the cured product has a linear expansion coefficient (α1) of 1.
0 to 1.6 (× 10 ⁻⁵ / ° C.).

A semiconductor device according to a fifth aspect of the present invention is characterized by being sealed with the epoxy resin composition according to any one of the first to fourth aspects.

[0015]

Embodiments of the present invention will be described below.

In the present invention, the epoxy resin represented by the formula (1) is used as the epoxy resin. The warpage of a package formed by sealing a sealing material made of an epoxy resin composition prepared using this epoxy resin on a package substrate on which a chip is mounted is determined by the glass transition temperature (Tg) of the cured product of the sealing material. ) Is increased and the volume change is reduced, so that it can be reduced. Furthermore, by combining with a phenol novolak resin represented by the formula (2) described below and having a binuclear body of 10% by mass or less, the warpage of the package can be further reduced and the chip and the package substrate can be further reduced. It can enhance the adhesion and prevent the occurrence of peeling, cracks, and the like due to reflow soldering.

In addition to the epoxy resin represented by the formula (1), for example, orthocresol novolak epoxy resin, phenol novolak epoxy resin, bisphenol type epoxy resin, biphenyl type epoxy resin, dicyclopentadiene type epoxy resin, etc. An epoxy resin generally compounded in the stopper can be used as a mixture. When such an epoxy resin is used in combination, the amount of the epoxy resin represented by the formula (1) is preferably 20% by mass or more based on the total amount of the epoxy resin,
More preferably, 50% by mass based on the total amount of the epoxy resin.
That is all. There is no particular upper limit for the amount of compounding, and 100% by mass.
Can be used. However, if the compounding amount is less than 20% by mass, the above-described effects may not be obtained at a high level.

As the curing agent, a phenol novolak resin represented by the formula (2) and having a binuclear content of 10% by mass or less is used. Here, the binucleate refers to a compound represented by m = 0 in the formula (2). And, by combining the above with the epoxy resin represented by the formula (1), the warpage of the package can be reduced and the reflow resistance can be improved. If the binuclear substance exceeds 10% by mass, the crosslink density is lowered, the glass transition temperature (Tg) is lowered, and the warpage of the package is increased.

In addition to the phenol novolak resin represented by the formula (2), which has a binuclear content of 10% by mass or less, for example, a phenol novolak resin, a naphthalene skeleton-containing phenol resin, a dicyclopentadiene type phenol resin, A curing agent generally compounded in a sealing material, such as a phenol aralkyl resin, can be mixed and used. When such a curing agent is used in combination, the binuclear is 10%.
The compounding amount of the phenol novolak resin represented by the formula (2) which is not more than 20% by mass is preferably not less than 20% by mass, more preferably not less than 50% by mass, based on the total amount of the curing agent. is there. There is no particular upper limit on the amount of the compound, and 100% by mass can be used. However, if the amount is less than 20% by mass, the warpage of the package may not be reduced.

The inorganic filler is not particularly limited. For example, it is possible to use inorganic fillers such as fused silica, crystalline silica, alumina, silicon nitride, and aluminum nitride which are generally blended in a sealing material. Can be. These can be used alone or in combination of two or more. By the way, as a package substrate such as a BGA, an organic substrate such as glass epoxy or BT (bismaleimide triazine resin) material is generally used, and the linear expansion coefficient (α1) of such a package substrate is used.
Is 1.3 to 1.7 (× 10 ⁻⁵ / ° C.). For this reason, if the linear expansion coefficient (α1) of the cured product is set slightly lower than that of the package substrate in consideration of the curing shrinkage of the sealing material, the warpage of the package can be reduced. . Therefore, it is preferable to mix the above-mentioned inorganic filler into the sealing material such that the linear expansion coefficient (α1) of the cured product falls within the range of 1.0 to 1.6 (× 10 ⁻⁵ / ° C.). . If the linear expansion coefficient (α1) of the cured product is out of the above range, the linear expansion coefficient (α1) of the sealing material and the package substrate
And the package may be easily warped.

When an imidazole is used as a curing accelerator, the glass transition temperature (Tg) of the cured product is increased, the change in volume is reduced, and the package is less likely to warp. The imidazoles are not particularly limited, and for example, 2-methylimidazole, 2-phenyl-4-methylimidazole, 2-phenylimidazole (2PZ) and the like can be used.
In addition, as a curing accelerator other than imidazoles, for example, organic phosphorus compounds such as triphenylphosphine (TPP) and trimethylphosphine, 1,8-diazabicyclo (5,4,0) undecene, triethanolamine,
Tertiary amines such as benzyldimethylamine can be used. These can be used alone or in combination of two or more. The amount of the curing accelerator is from 0.03 to the total amount of the epoxy resin composition.
It is preferably 1.0% by mass. 0.03
If it is less than mass%, the gelation time of the sealing material will be delayed,
There is a possibility that the stiffness at the time of curing is reduced and the workability is deteriorated. Conversely, if the content exceeds 1.0% by mass, the curing reaction proceeds during molding, and voids and unfilled portions may be easily generated.

In addition to the above components, silicone rubber powder can be added to the sealing material. At this time, it is preferable that the surface of the silicone rubber powder be covered with a silicone resin. By doing so, it is possible to reduce the warpage of the package without impairing the adhesion between the chip or the package substrate and the sealing material. In addition, a commercially available thing can be used as a silicone rubber powder and a silicone resin. However,
The average particle size of the silicone rubber powder is 0.5-20μ
m is preferable. If the average particle size is out of the above range, the flowability of the sealing material during molding is reduced,
There is a possibility that the aforementioned adhesiveness may be reduced. The amount of the silicone rubber powder is preferably 0.3 to 5.0% by mass based on the total amount of the epoxy resin composition. If the amount is outside the above range, the fluidity of the sealing material during molding may be reduced.

Further, in addition to the above components, additives generally compounded in the sealing material can be appropriately compounded and used. For example, as a release agent, carnauba wax,
As the flame retardant, phosphorus-based flame retardants, bromo compounds, antimony trioxide, etc., and as the colorant, carbon black,
Organic dyes and the like can be used as coupling agents such as γ-glycidoxypropyltriethoxysilane.

The epoxy resin composition according to the present invention contains the above-mentioned epoxy resin, curing agent, inorganic filler, and curing accelerator as essential components, and further includes a releasing agent, a flame retardant, a coloring agent, and a coupling as required. The composition can be prepared by blending an agent and the like, uniformly mixing the mixture with a mixer, a blender, or the like, and then kneading the mixture with a kneader or a roll. In addition, the order which mix | blends each component is not specifically limited.
Further, the obtained kneaded material may be cooled and solidified as required, and then pulverized into a powder form or a tablet form for use.

Then, a semiconductor device can be manufactured by sealing and molding using the epoxy resin composition prepared as described above. For example, by setting a package substrate on which a chip such as an IC is mounted in a transfer molding die and performing transfer molding,
A semiconductor device in which a chip mounting surface is sealed with a sealing material of an epoxy resin composition can be manufactured.

The semiconductor device thus obtained does not have an imbalance in shrinkage between the chip or package substrate and the encapsulant during cooling from immediately after molding to room temperature, and warpage does not occur. When the semiconductor device is mounted on a mounting substrate, peeling and package cracking do not occur between the chip or the package substrate and the sealing material even when reflow soldering is performed.

[0027]

The present invention will be specifically described below with reference to examples.

[0028] The blends of Tables 1 and 2 were uniformly mixed by a mixer, and then kneaded with a heating roll for about 5 minutes to obtain epoxy resin compositions of Examples 1 to 6 and Comparative Examples 1 to 4. .

In Tables 1 and 2, "ESCN195XL" manufactured by Sumitomo Chemical Co., Ltd. was used as an orthocresol novolak epoxy resin, and "EPPN501HY" manufactured by Nippon Kayaku Co., Ltd. was used as an epoxy resin represented by the formula (1).
As a general phenol novolak resin, "H-1" manufactured by Meiwa Kasei Co., Ltd. (the dinuclear is about 15% by mass), and as a phenol novolak resin represented by the formula (2), "DL-" manufactured by Meiwa Kasei Co., Ltd. 92 "(about 4% by mass of binucleate)
As brominated epoxy resin, "ES" manufactured by Sumitomo Chemical Co., Ltd.
B400 "was used.

As a curing accelerator, 2-phenylimidazole (2PZ), triphenylphosphine (TP)
P) as an inorganic filler, γ-
Fused silica (average particle size: 15 μm) treated with glycidoxypropyltriethoxysilane was used.

As a silicone rubber powder whose surface is coated with a silicone resin, "KMP" manufactured by Shin-Etsu Chemical Co., Ltd.
“-601” (average particle size: 5 μm) as “E601” manufactured by Toray Dow Corning Silicone Co., Ltd. as a silicone rubber powder whose surface is not coated with silicone resin.
(Average particle size: 2 μm). The silicone rubber powder has an epoxy group.

Antimony trioxide is used as a flame retardant,
Carnauba wax was used as a release agent.

Next, the performance of the epoxy resin composition obtained as described above was evaluated by the following tests. The results are summarized in Tables 1 and 2. (BGA Package Warpage) As shown in FIG. 1A, a BT (bismaleimide triazine resin) material is used as the package substrate 3, and a TEG for evaluation is formed on the package substrate 3.
With chip 2 mounted, external size 7.6mm x 7.6m
mx 0.4 mm, set in a mold for BGA, and using the molding materials of Examples 1 to 6 and Comparative Examples 1 to 4,
Transfer molding was performed on this mold. The molding conditions were as follows: temperature 170 ° C., injection pressure 9.8 MPa, injection speed 10
Seconds, cure time 120 seconds, temperature after molding 17
By performing after-curing at 5 ° C. for 6 hours, a BGA package in which the thickness of the sealing material 1 was 0.8 mm was obtained.

With respect to the BGA package thus obtained, two warpages indicated by arrows in FIG. 1B were measured using a surface roughness meter. (Reflow resistance) After drying the above BGA package at 125 ° C. for 24 hours as a pre-treatment, the BGA package was dried at 30 ° C. and 70% R
H was subjected to a moisture absorption treatment for 168 hours using a thermo-hygrostat.
The GA package was subjected to an IR reflow process (EIAJ standard). The interior of the BGA package after this processing is observed with an ultrasonic probe (“M-700II” manufactured by Canon Inc.), and the interface between the sealing material and the chip and the interface between the sealing material and the package substrate are observed. The presence or absence of peeling or cracks between them was examined. Number of occurrences of peeling (numerator) against evaluation number (denominator)
Indicated by (Glass transition temperature (Tg)) The epoxy resin composition obtained as described above was analyzed by TMA to obtain (α1 (80 to 12)
Glass transition temperature (Tg) was measured (as the intersection of 0 ° C.) and α2 (220-260 ° C.). (Linear Expansion Coefficient (α1)) The linear expansion coefficient (α1) (in a temperature range of 80 to 120 ° C.) of the epoxy resin composition obtained as described above was measured by TMA.

[0035]

[Table 1]

[0036]

[Table 2]

As shown in Table 1, it is confirmed that each of the examples has excellent reflow resistance and small warpage of the BGA package.

Further, comparing Example 1 and Example 2,
It is confirmed that the addition of silicone rubber powder whose surface is coated with silicone resin reduces the warpage of the BGA package.

Further, comparing Example 1 and Example 3,
It is confirmed that the use of imidazoles as a curing accelerator reduces the warpage of the BGA package and increases the glass transition temperature (Tg).

As can be seen from Table 2, since the epoxy resin represented by the formula (1) was not blended as the epoxy resin in Comparative Examples 1 and 2, it was found that the resin had poor reflow resistance. It is confirmed.

In Comparative Examples 3 and 4, among the Comparative Examples, although excellent in reflow resistance, the curing agent is represented by Formula (2) in which the binuclear body is 10% by mass or less. Because phenol novolak resin is not blended,
It is confirmed that the warpage of the BGA package increases.

[0042]

As described above, the epoxy resin composition according to claim 1 of the present invention is represented by the following formula (2) in which the content of the epoxy resin represented by the formula (1) is 2% by mass or less. Since it contains a phenol novolak resin, an inorganic filler, and a curing accelerator, the epoxy resin represented by the formula (1) increases the glass transition temperature (Tg) of the cured product, reduces the volume change, and warps the package. Can be reduced. In addition, by combining with a phenol novolak resin represented by the formula (2) in which the binuclear body is 10% by mass or less, the warpage of the package can be further reduced, and the adhesion to the chip or the package substrate is enhanced. It is possible to prevent the occurrence of peeling or cracks due to reflow soldering.

According to a second aspect of the present invention, since the first aspect of the present invention comprises the silicone rubber powder whose surface is coated with the silicone resin, the adhesion between the chip or the package substrate and the sealing material may be impaired. In addition, excellent reflow resistance can be maintained and package warpage can be reduced.

According to a third aspect of the present invention, in the first or second aspect, since the curing accelerator is an imidazole, the glass transition temperature (Tg) of the cured product is increased, and the volume change with respect to the temperature change can be reduced. This makes the package less likely to warp.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the cured product has a linear expansion coefficient (α1) of 1.
0 to 1.6 (× 10 ⁻⁵ / ° C.), which is slightly lower than the linear expansion coefficient (α1) of a package substrate made of glass epoxy, BT (bismaleimide triazine resin), etc., and reduces package warpage. Is what you can do.

A semiconductor device according to a fifth aspect of the present invention is sealed with the epoxy resin composition according to any one of the first to fourth aspects, so that there is no warpage, and further the semiconductor device is mounted on a mounting substrate. Even when reflow soldering is performed, the adhesion between the chip or package substrate and the epoxy resin composition is enhanced, and peeling and package cracking do not occur.

[Brief description of the drawings]

FIGS. 1A and 1B show a BGA package, wherein FIG. 1A is a cross-sectional view and FIG. 1B is a plan view.

[Explanation of symbols]

 1 sealing material 2 TEG chip for evaluation 3 package substrate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 23/31 F-term (Reference) 4J002 CC04X CD07W CP033 DE146 DF016 DJ006 DJ016 EN027 EU117 EW137 FB263 FD016 FD157 GQ05 4J036 AA01 AC01 AD01 DC02 DC05 DC41 DD07 FA05 FA06 FB07 JA07 4M109 AA01 EA04 EB04 EB12 EB18 EC05 GA10

Claims (5)

[Claims] An epoxy resin represented by the following formula (1):
An epoxy resin composition comprising a phenol novolak resin represented by the following formula (2) in which the binuclear body is 10% by mass or less, an inorganic filler, and a curing accelerator. Embedded image 2. The epoxy resin composition according to claim 1, comprising a silicone rubber powder whose surface is coated with a silicone resin. 3. The epoxy resin composition according to claim 1, wherein the curing accelerator is an imidazole. 4. The cured product has a linear expansion coefficient (α1) of 1.0 to 1.0.
The epoxy resin composition according to claim 1, wherein the epoxy resin composition is 1.6 (× 10 ⁻⁵ / ° C.). 5. A semiconductor device which is sealed with the epoxy resin composition according to claim 1.