JP2001200139A - Liquid epoxy resin composition for semiconductor sealing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid epoxy resin composition for semiconductor sealing, capable of providing a cured product having good property penetrating into narrow gap and low flexural modulus. SOLUTION: This liquid epoxy resin composition for semiconductor sealing consists essentially of (A) a liquid epoxy resin, (B) a curing agent and (C) an inorganic filler. The resin composition is characterized in that the inorganic filler has <=1 wt.% content of particles having >=45 μm average diameter and average particle diameter thereof is 1-5 μm and particle size distribution thereof has peaks in a particle diameter range of 0.5 to 2 μm and in a particle diameter range of 5-10 μm and a ratio A/B of an amount A (wt.%) of particle in the range of 0.5-2 μm particle diameter to an amount B (wt.%) in the range of 5-10 μm particle diameter is 1-20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitably used as a potting material or a coating material for a semiconductor device, and is particularly excellent in storage stability as a flip-chip underfill material and the like, and a semiconductor sealing material having excellent gap penetration. The present invention relates to a liquid epoxy resin composition for stopping.

[0002]

2. Description of the Related Art With the miniaturization, weight reduction, and enhancement of functions of electric equipment, semiconductor mounting methods have become the mainstream from pin insertion type to surface mounting. And one of bare chip mounting is flip chip (FC)
There is an implementation. FC mounting is a method in which several to thousands of electrodes called bumps having a height of about 10 to 100 μm are formed on the wiring pattern surface of an LSI chip, and the electrodes on the substrate are joined by a conductive paste or solder. For this reason, it is necessary that the sealing material used to protect the FC penetrates into a gap of about several tens of μm (normally about 40 μm to 20 μm) formed by bumps of the substrate and the LSI chip. The liquid epoxy resin composition used as the conventional underfill material for flip chips is composed of an epoxy resin, a hardener and an inorganic filler. In order to achieve the same, a formulation incorporating a large amount of an inorganic filler has become mainstream.

[0003] However, such an underfill material for a flip chip containing a large amount of an inorganic filler has a problem that it hardly penetrates into a narrow gap (about 40 μm to 20 μm), and the productivity is extremely deteriorated. This has been suggested and this improvement is desired. In this case, if the particle size of the inorganic filler is small, it can be easily presumed that the narrow gap can be accommodated.However, the reduction in the particle size causes an increase in the elastic modulus of the cured product, thereby relaxing the stress in the cured product. However, it has been pointed out that the problem is that the peeling and cracking easily occur.

The present invention has been made in view of the above circumstances, and provides a highly reliable liquid epoxy resin composition for semiconductor encapsulation which is excellent in invasiveness and can obtain a cured product having a low elastic modulus. The purpose is to:

[0005]

Means for Solving the Problems and Embodiments of the Invention The present inventors have conducted intensive studies in order to achieve the above object and found that (A) a liquid epoxy resin, (B) a curing agent, and (C) an inorganic material. In the liquid epoxy resin composition containing a filler, the content of particles having a particle diameter of 45 μm or more is 1% by weight or less and the average particle diameter is 1 to 5 μm as the inorganic filler.
m, the particle size distribution has peaks in the particle size range of 0.5 to 2 μm and the particle size range of 5 to 10 μm, respectively, and the particle amount A in the particle size range of 0.5 to 2 μm.
By using an inorganic filler having a ratio A / B of 1 to 20 (% by weight) and a particle amount B (% by weight) in a particle size range of 5 to 10 μm, good gap penetration and low elasticity are obtained. It has been found that a liquid epoxy resin composition capable of obtaining a cured product having a high degree of yield can be obtained.

[0006] In particular, spherical silica is used as an inorganic filler in an underfill material due to its fluidity, but if it contains a large amount of particles larger than the gap,
Particles are caught by the gate, narrowing the penetration cross section, affecting the penetration, but by removing as much as possible particles having a maximum particle diameter of 45 μm or more and controlling the average particle diameter to 1 to 5 μm, the narrow gap can be reduced. In order to be able to satisfactorily penetrate, and at that time, in order to prevent an increase in the modulus of elasticity by reducing the particle size, the particle size distribution has two peaks A and B. A certain 0.5 to 2 μm weight% and B
It has been found that by controlling the ratio A / B to the weight% of 10 μm to 1 to 20, the stress relaxation of the cured product can be achieved.

Therefore, the liquid epoxy resin composition for semiconductor encapsulation of the present invention was found to have a very good gap penetration property, and found that the cured product thereof had a low elastic modulus. It is a thing.

Hereinafter, the present invention will be described in more detail.
Liquid epoxy resin composition for semiconductor encapsulation of the present invention,
It contains (A) a liquid epoxy resin, (B) a curing agent, and (C) a specific inorganic filler described below as essential components.

As the liquid epoxy resin of the component (A) used in the present invention, any one can be used as long as it has two or more epoxy groups in one molecule. In particular, bisphenol A type epoxy resin, bisphenol A Examples include bisphenol-type epoxy resins such as F-type epoxy resins, phenol novolak-type epoxy resins, novolak-type epoxy resins such as cresol-novolak-type epoxy resins, naphthalene-type epoxy resins, biphenyl-type epoxy resins, and cyclopentadiene-type epoxy resins. Among them, a liquid epoxy resin is used at room temperature (25 ° C.).
In particular, bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin are desirable. There is no problem even if an epoxy resin represented by the following structure is added to these epoxy resins within a range that does not affect the penetration.

[0010]

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The total chlorine content in the liquid epoxy resin is 1,500 ppm or less, preferably 1,000 pp
m or less. 50% at 100 ° C
Extraction water chlorine in 20 hours at epoxy resin concentration is 1
It is preferably at most 0 ppm. If the total chlorine content exceeds 1,500 ppm and the amount of extracted water chlorine exceeds 10 ppm, the reliability of the semiconductor element, particularly, the moisture resistance may be adversely affected.

Next, known curing agents can be used as the component (B), but acid anhydrides are particularly preferred. Examples of the acid anhydride include tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, hexahydrophthalic anhydride, methylhymic anhydride, pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, 3,3 ', 4,4'
-Biphenyltetracarboxylic dianhydride, bis (3,4
-Dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride,
It preferably has one or two aliphatic or aromatic rings in the molecule, such as 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, and has an acid anhydride group (-C
Having 1 or 2 O—O—CO—) and having 4 carbon atoms
Acid anhydrides of up to 25, preferably about 8 to 20 are suitable.

When such an acid anhydride is used as a curing agent, the ratio of the acid anhydride group (—CO—O—CO—) in the curing agent to 1 mol of the epoxy group in the epoxy resin is set to 0.1.
Desirably, the range is 3 to 0.7 mol. If it is less than 0.3 mol, the curability is insufficient, and if it exceeds 0.7 mol, unreacted acid anhydride remains and the glass transition temperature may be lowered. More preferably, it is in the range of 0.4 to 0.6 mol.

As the curing agent, carboxylic acid hydrazides such as dicyandiamide, adipic hydrazide and isophthalic hydrazide can be used in addition to the above.

Further, if necessary, the composition of the present invention comprises:
One or more selected from imidazole compounds, tertiary amine compounds, and organic phosphorus compounds can be blended. Here, as the imidazole compound, 2-methylimidazole, 2-ethylimidazole, 4-methylimidazole, 4-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 2-phenyl-4-hydroxymethyl Imidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-methylimidazole, 2-phenyl-4-
Methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole and the like can be mentioned. Examples of the tertiary amine compound include amine compounds having an alkyl group or an aralkyl group as a substituent bonded to a nitrogen atom, such as triethylamine, benzyltrimethylamine, and α-methylbenzyldimethylamine.
1,8-diazabicyclo [5.4.0] undecene-7
And a salt thereof with a cycloamidine compound such as a phenol salt, an octylate salt or an oleate salt, or an organic acid thereof, or a salt or a complex salt of a cycloamidine compound such as a compound of the following formula with a quaternary boron compound.

[0016]

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Examples of the organic phosphorus compounds include triorganophosphine compounds such as triphenylphosphine and quaternary phosphonium salts such as tetraphenylphosphonium tetraphenylborate.

The compounding amount is 0 to 10 parts by weight, preferably 0.01 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the total of the epoxy resin and the curing agent.
Parts by weight. If the amount is less than 0.01 part by weight, the curability is reduced. If the amount is more than 10 parts by weight, the curability is excellent, but the storage stability tends to be reduced.

Next, the epoxy resin composition of the present invention comprises:
As the component (C), various inorganic fillers conventionally known for the purpose of reducing the expansion coefficient are added. As the inorganic filler, fused silica, crystalline silica, alumina, boron nitride, aluminum nitride, silicon nitride, magnesia, magnesium silicate and the like are used.

In this case, in the present invention, the content of particles having a particle diameter of 45 μm or more is 1% by weight as the inorganic filler.
Or less (that is, 0 to 1% by weight), and the average particle size is 1 to
5 μm, and 0.5 to 2 μm in the particle size distribution.
And a particle amount A (% by weight) having a particle size range of 0.5 to 2 μm and a particle amount B having a particle size range of 5 to 10 μm, respectively.
(Weight%) A / B is 1 to 20, preferably 1.5
The one that is 10 to 10 is used. In the present invention,
The average particle diameter can be determined, for example, as a weight average value (or median diameter) by a laser light diffraction method.

More specifically, the average particle diameter of the inorganic filler is 1 to 5 μm, preferably 1.2 to 2.5 μm, and the content of particles having a particle diameter of 45 μm or more is 1% by weight or less,
Preferably it is 0.5% by weight or less. Average particle size is 5μ
If the particle size exceeds 45 m, the resistance to flow becomes large,
If the content of particles having a size of μm or more exceeds 1% by weight, the particles are caught by the gate, the cross-sectional area of penetration is reduced, and the penetration is affected. On the other hand, if the average particle size is less than 1 μm, it becomes undesirably high viscosity. In the particle size distribution, there are two peaks A and B. In each size, A is 0.5 to 2 μm weight% and B is 5 to 10 μm.
A / B with respect to the weight% of 1 to 20, preferably 1.5 to
You need to control to 10. When the top size shifts to a large particle size, particles hardly enter the gate, whereas when the top size shifts to a small particle size, the viscosity increases too much and adversely affects the penetration.

The compounding amount is 100 to 400 parts by weight based on 100 parts by weight of the total amount of the epoxy resin and the curing agent, and preferably 150 to 250 parts by weight based on 100 parts by weight of the total amount of the epoxy resin and the curing agent. It is preferable to mix in the range of parts by weight. If the amount is less than 100 parts by weight, the coefficient of expansion is large, and cracks may be generated in a thermal test. If it exceeds 400 parts by weight, the viscosity increases,
There is a possibility that the thin film penetration may be reduced.

The composition of the present invention may contain a thermoplastic resin such as silicone rubber, silicone oil, liquid polybutadiene rubber, or methyl methacrylate-butadiene-styrene copolymer for the purpose of reducing stress. Preferably, the alkenyl group of the alkenyl group-containing epoxy resin or the phenol resin and the number of silicon atoms in one molecule represented by the following formula (1) are 10 to 400, preferably 40 to 200, and a SiH group (that is, It is preferable to blend a copolymer obtained by an addition reaction of an organohydrogenpolysiloxane having 1 to 5 and preferably 2 hydrogen atoms bonded to silicon atoms with SiH groups. H _a R _b SiO _{(4-ab) / 2} (1) (wherein, R is a substituted or unsubstituted monovalent hydrocarbon group, a is 0.005 to 0.1, b is 1.8 to 2. 2, 1.81 ≦
It indicates a positive number satisfying a + b ≦ 2.3. )

The monovalent hydrocarbon group of R preferably has 1 to 10 carbon atoms, particularly 1 to 8 carbon atoms.
Ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, tert-butyl group, hexyl group, cyclohexyl group, octyl group, alkyl group such as decyl group, vinyl group, allyl group, propenyl group, butenyl group, hexenyl group Alkenyl groups such as phenyl group, xylyl group, and tolyl group; aralkyl groups such as benzyl group, phenylethyl group, and phenylpropyl group; and a part or all of hydrogen atoms of these hydrocarbon groups. A chloromethyl group substituted by a halogen atom such as fluorine, bromine,
Examples thereof include a halogen-substituted monovalent hydrocarbon group such as a bromoethyl group and a trifluoropropyl group. Among the above copolymers, those having the following structures are particularly desirable.

[0025]

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[0026]

Embedded image(Wherein R is the same as above, R¹¹Is a hydrogen atom or carbon
An alkyl group of the formulas 1-4, R¹²Is -CH_TwoCH_TwoCH_Two−,
-OCH_Two-CH (OH) -CH_Two-O-CH_TwoCH _TwoCH
_Two-Or -O-CH_TwoCH_TwoCH_Two-. n is 8 to 39
8, preferably an integer of 38 to 198, and p is an integer of 1 to 10.
The number and q are integers of 1 to 10. )

The copolymer is blended so that the diorganopolysiloxane unit is contained in an amount of 0 to 20 parts by weight, particularly 2 to 15 parts by weight, based on 100 parts by weight of the total amount of the liquid epoxy resin and the curing agent. , The stress can be further reduced.

The liquid epoxy resin composition of the present invention may further contain, if necessary, a pigment such as a carbon-functional silane for improving adhesion, carbon black, a dye, an antioxidant, and other additives.

The epoxy resin composition of the present invention is, for example,
It can be produced by stirring, dissolving, mixing, and dispersing an epoxy resin, a curing agent, an inorganic filler, and a curing accelerator, if necessary, simultaneously or separately while adding a heat treatment as needed. The apparatus for mixing, stirring, and dispersing the mixture is not particularly limited, but a raikai machine equipped with a stirring and heating device, a three-roll mill, a ball mill, a planetary mixer, or the like can be used. These devices may be used in appropriate combination.

The liquid epoxy resin composition of the present invention is used for encapsulating a semiconductor device as a potting material, a coating material and the like, and is particularly suitably used as an underfill material for a flip-chip type semiconductor device.

The viscosity of the liquid epoxy resin composition of the present invention is preferably not more than 10,000 poise at 25 ° C.

The molding method and molding conditions for encapsulating a semiconductor using the composition of the present invention can be conventional methods. Particularly, as the underfill material, the resin composition is introduced into the voids of the device. Temperature conditions for sealing are 60 to 12
0 ° C., more preferably 70 to 10 ° C.
0 ° C. If the temperature is lower than 60 ° C., the viscosity of the composition is high, so that the gap between the substrate and the chip cannot be penetrated,
On the other hand, when the temperature exceeds 120 ° C., a reaction occurs, which may also hinder penetration. In addition, the molding and curing conditions after the resin composition is intruded and sealed are 0.5 to 150 ° C.
About two hours are preferable.

[0033]

EXAMPLES The present invention will be described below in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples 1 to 4] 22.5 parts by weight of a bisphenol A type epoxy resin (RE310: manufactured by Nippon Kayaku Co., Ltd.) as a liquid epoxy resin and an acid anhydride (methyltetrahydrophthalic anhydride, MH700) as a curing agent: 11.0 parts by weight of Shin Nippon Rika Co., Ltd., 50.0 parts by weight of spherical silica, and 0.5 parts by weight of a silane coupling agent (γ-glycidoxypropyltrimethoxysilane, KBM403: Shin-Etsu Chemical Co., Ltd.) Part, curing accelerator (complex salt of cycloamidine compound and quaternary boron compound, U-CAT5002:
6.0 parts by weight of Asahi Kasei Co., Ltd.) were mixed and uniformly kneaded to obtain an epoxy resin composition. As the spherical silica, a silica having a particle size distribution shown in Table 1 and FIGS. 1 to 4 from which coarse particles of 325 mesh were removed by a sieve of 325 mesh (corresponding to a mesh size of 44 μm) was used.

The obtained epoxy resin composition has a thickness of 40 μm.
Was placed on a hot plate, heated to 100 ° C., and penetrated into the gap between the glass plates. The penetration time was set to the time required for penetration of 2 cm, and the penetration was evaluated. The epoxy resin composition was cured at 150 ° C. for 2 hours, and the flexural modulus of the cured product was measured.

Comparative Example 1 As an inorganic filler, 100
The evaluation was performed in the same manner as in the above example except that those having a particle size distribution shown in Table 1 and FIG. 5 from which coarse particles of 100 mesh-on were removed by a mesh (equivalent to a screen mesh of 149 μm) sieve were used.

Comparative Example 2 325 was used as the inorganic filler.
Except that 325 mesh-on coarse particles were removed with a mesh sieve and coarse particles on the sieve were used as shown in Table 1 except that the one having the particle size distribution shown in Table 1 was intentionally added at the time of blending. It evaluated similarly. The particle size distribution before the addition of coarse particles is the same as that in FIG.

Comparative Example 3 Evaluation was performed in the same manner as in Example except that silica having an average particle diameter of 0.75 μm different from that of Example and having a particle size distribution shown in FIG. 6 was used as an inorganic filler. did.

Comparative Example 4 Evaluation was performed in the same manner as in Example except that silica having a different average particle diameter of 1.53 μm from Table 1 and having a particle size distribution shown in FIG. 7 was used as the inorganic filler. did. Table 1 also shows the results of the penetration and the flexural modulus of the above Examples and Comparative Examples.

[0040]

[Table 1] A: Content of particle size 0.5 to 2 μm (% by weight) B: Content of particle size 5 to 10 μm (% by weight)

[0041]

The liquid epoxy resin composition for encapsulating a semiconductor according to the present invention has good penetration into a narrow gap and gives a cured product having a low flexural modulus.

[Brief description of the drawings]

FIG. 1 is a particle size distribution of silica in Example 1.

FIG. 2 is a particle size distribution of silica in Example 2.

FIG. 3 is a particle size distribution of silica before adding coarse particles in Example 3 and Comparative Example 2.

FIG. 4 is a particle size distribution of silica in Example 4.

FIG. 5 is a particle size distribution of silica in Comparative Example 1.

FIG. 6 is a particle size distribution of silica in Comparative Example 3.

FIG. 7 is a particle size distribution of silica in Comparative Example 4.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshio Shiohara 1-10 Hitomi, Matsuida-cho, Usui-gun, Gunma Prefecture, Japan Silicone Electronic Materials Technology Laboratory, Shin-Etsu Chemical Co., Ltd.

Claims (2)

[Claims] 1. A liquid epoxy resin composition comprising (A) a liquid epoxy resin, (B) a curing agent, and (C) an inorganic filler as essential components, wherein the inorganic filler has a particle diameter of 45%.
The content of particles having a particle size of 1 μm or more is 1% by weight or less, the average particle size is 1 to 5 μm, and the particle size distribution is 0.5
Particles having a peak in the particle size range of 2 to 2 μm and a particle size range of 5 to 10 μm, respectively, and having a particle amount A (% by weight) in the particle size range of 0.5 to 2 μm and a particle in the particle size range of 5 to 10 μm A liquid epoxy resin composition for semiconductor encapsulation, wherein the ratio A / B to the amount B (% by weight) is 1 to 20. 2. The composition according to claim 1, which is used for an underfill material of a flip-chip type semiconductor device.