JP2000003983A - Liquid sealing material fused spherical silica and liquid sealing resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance clearance permeability for sealing a slight clearance between a substrate and an IC chip, by a method wherein fused spherical silica having specified particle size characteristics is arranged to a liquid epoxy resin or silicon resin at a standard temperature. SOLUTION: Particles having a liquid epoxy resin, or silicon resin A at a standard temperature and the maximum particle size 24 μm, the average particle size 2 to 7 μm 1 μm or less have a particle size distribution of 1% or less of the entire, and a fused spherical silica filler B in the range of a BET ratio surface area 3 m2/g or less and a spherical degree 0.91 to 0.99 is contained, an arrangement amount of B is 30 to 80 wt.% in a liquid sealing resin composition. Furthermore, for measurement of a maximum particle size, a standard particle size and a size distribution, a laser method micro-track size analyzer, etc., is used. Furthermore, in this liquid sealing fused spherical silica, Na ions and Cl ions in boiling extracted water are respectively 1 ppm or less as ionic impurities, and U and Th are respectively 1 ppb or less as radiant impurities, preferably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid sealing resin composition for sealing a small gap between a substrate and an IC chip, and a fused spherical silica compounded therein.

[0002]

2. Description of the Related Art Demands for higher performance and higher functionality of electronic devices have been increasing in the multimedia age.
Along with this, the form of the 1C package used for the electronic device has also been reduced in size, thickness, and number of pins. The semiconductor chip is sealed with an encapsulant to protect fine and complicated electronic circuits formed on the surface thereof from dust and moisture in the air.
The whole C chip is sealed and molded. At present, an epoxy resin sealing material is most often used as a sealing material for a semiconductor IC chip. This epoxy resin encapsulant is roughly classified into an epoxy resin encapsulant for transfer molding and a liquid epoxy resin encapsulant. The use of the resin sealing material has been limited so far.

[0003] However, this liquid epoxy resin sealing material is
Recently, P-PGA (Plastic Pin Grid Array), P
-BGA (Plastic Ball Grid Array), flip chip or CSP (Chip Saize Package or Chip Scale)
Package) and other advanced semiconductor devices. Among them, CSPs often have small and complicated structures as compared with conventional devices. CS
The gap (gap) between the P substrate and the IC chip has conventionally been about 75 to 100 μm, but in recent years, the bump size has been reduced due to the narrow pitch accompanying the increase in the pitch, and the gap has also been reduced to 30 μm. Semiconductor devices having a gap size of 1 mil (25.4 μm) have been developed as advanced semiconductor devices.

In order to seal such advanced semiconductor devices, finer workability than before is required.
As a sealing material that can respond to this, development of a liquid epoxy resin sealing material having excellent gap permeability is strongly desired.

On the other hand, a conventional liquid epoxy resin encapsulant includes a liquid encapsulant and an IC in order to improve the reliability of the encapsulant.
There is a problem that the stress generated due to the difference in the coefficient of linear expansion from the chip is reduced. As a solution to this, there is a method in which a large amount of silica filler is incorporated into the liquid epoxy resin encapsulant to reduce the coefficient of linear expansion, and this solves the fluidity problem associated with the large amount of silica filler. Many methods using fine fused spherical silica having excellent low-viscosity characteristics have been proposed (Japanese Patent Laid-Open No. 2-5 / 1990).
No. 9416, JP-A-2-199013).

[0006]

However, the conventional liquid epoxy resin encapsulant can be filled with a large amount of silica filler, has high reliability, and has a small amount of space between the substrate of the most advanced semiconductor device and the IC chip. It is hard to say that it has gap permeability that seals the gap. Therefore, development of a liquid epoxy resin encapsulant having high reliability and excellent gap permeability and silica for a liquid encapsulant which imparts this performance from the silica filler side are desired.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a liquid sealing resin composition having excellent gap permeability for sealing a small gap between a substrate and an IC chip and having high reliability, and a fused spherical silica filled therein. It is to provide a filler.

[0008]

Under such circumstances, the present inventors have conducted intensive studies and as a result, have found that fused spherical silica having a specific particle size characteristic in an epoxy resin or silicone resin which is liquid at normal temperature, particularly particles having a particle size of 1 μm or less. Is 1% or less, and the sphericity is O. A liquid sealing resin composition containing fused spherical silica in the range of 91 to 0.99 solves the above-mentioned problems, has excellent gap permeability for sealing a small gap between a substrate and an IC chip, and is reliable. The inventors have found that the present invention has high performance, and have completed the present invention.

That is, according to the present invention, the maximum particle size is 24 μm.
m, average particle diameter of 2 to 7 μm, particles of 1 μm or less have a particle size distribution of 1% or less of the whole particles, and BET specific surface area of 3% or less.
An object of the present invention is to provide a fused spherical silica for a liquid sealing material, wherein the fused spherical silica has a m ² / g or less and a sphericity in a range of 0.91 to 0.99.

Further, the present invention relates to (A) an epoxy resin or a silicone resin which is liquid at room temperature, and (B) particles having a maximum particle diameter of 24 μm, an average particle diameter of 2 to 7 μm, and 1 μm or less of 1% of the total particles. A fused spherical silica filler having the following particle size distribution, a BET specific surface area of 3 m ² / g or less, and a sphericity in the range of 0.91 to 0.99;
Is 30 to 80% by weight in the liquid sealing resin composition.
It is intended to provide a liquid sealing resin composition characterized by the following.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The fused spherical silica for liquid encapsulation of the present invention has a spherical shape and a particle size characteristic of a maximum particle diameter of 24 μm, an average particle diameter of 2 to 7 μm, and particles of 1 μm or less. , A BET specific surface area of 3 m ² / g or less, and a sphericity in the range of 0.91 to 0.99. When crushed silica is used as a liquid sealing resin composition, the viscosity is undesirably high. The measurement of the maximum particle diameter, the average particle diameter, and the particle size distribution may be performed using a laser method microtrack particle size analyzer or the like.

The preferred range of the maximum particle size of the fused spherical silica for liquid sealing of the present invention is 22 μm. By setting the maximum particle diameter of the fused spherical silica to 24 μm or less, when a liquid sealing resin composition is used, it can be sufficiently penetrated into the gap between the CSP substrate and the IC chip. The preferred range of the average particle size is 3 to 7, and the particularly preferred range is 3.3 to 6.6 µm. If the average particle diameter of the fused spherical silica for liquid sealing exceeds 7 μm, it is difficult to reduce the maximum particle diameter to 24 μm or less even by a classification means. Further, when the average particle size is less than 2 μm, the proportion of particles having a particle size of 1 μm or less in the whole particle size distribution increases, and when a liquid sealing resin composition is used, the viscosity increases,
As a result, the gap permeability deteriorates.

Further, a preferable value of a ratio of particles of 1 μm or less to the whole particle size distribution of the fused spherical silica for liquid sealing of the present invention is 0.96% or less. There is a particularly strong correlation between the ratio of particles having a particle size of 1 μm or less to the whole particle size distribution and the viscosity when the fused spherical silica is mixed with the resin. That is, when the ratio of the particles having a particle size of 1 μm or less exceeds 1%, the viscosity of the liquid sealing material rises sharply, and the gap permeability deteriorates. The preferred range of the BET specific surface area of the fused spherical silica for liquid sealing of the present invention is 2.8 m ² / g or less. If the value of the BET specific surface area exceeds 3 m ² / g, the increase in viscosity becomes large and the gap permeability becomes poor.

The preferred range of the sphericity of the fused spherical silica particles for liquid sealing of the present invention is 0.93 to 0.9.
8, a more preferred range is 0.94 to 0.98. The fused spherical silica particles having a sphericity outside the range of 0.91 to 0.99 are inferior in gap permeability. The sphericity is a value obtained by image analysis processing and calculated by the square of 4π × surface area / perimeter. The image analysis device used for such image analysis processing is not particularly limited, for example, Im
age Pro Plus (made by Planetron). As the value of sphericity approaches 1, it becomes closer to a true sphere. Therefore, the fused spherical silica for liquid sealing of the present invention is very nearly spherical.

The method for obtaining the fused spherical silica for liquid encapsulation of the present invention is not particularly limited, but a high-purity silica gel synthesized by a wet reaction between an alkali silicate and a mineral acid is prepared, and then the high-purity silica gel is used. Pulverized by a pulverizer such as a ball mill or a jet mill to obtain, for example, fused pulverized silica having an average particle diameter of 5 μm. This fused and ground silica is supplied to a melting furnace and melted in an oxygen-LPG mixed flame at a temperature equal to or higher than the melting point of silica, and then the melted silica is rapidly cooled and then collected by a cyclone to obtain a fused spherical silica. The method is preferred. This fused spherical silica may be subjected to a classification treatment as needed to obtain a fused spherical silica for liquid sealing having a particle size characteristic in the above range.

The fused spherical silica for liquid encapsulation according to the present invention is characterized in that Na ions and Cl ions in boiling extraction water are each 1 ppm or less as ionic impurities, and U and Th as radioactive impurities are each 1 ppb or less. Is preferred. It is known that a large amount of ionic impurities causes a so-called soft error. In particular, care must be taken when using it for sealing a semiconductor memory device.

Further, the liquid sealing resin composition of the present invention comprises:
(A) Epoxy resin or silicone resin which is liquid at normal temperature and (B) maximum particle size is 24 μm, average particle size is 2 to 7 μm
m, particles having a particle size of 1 μm or less have a particle size distribution of 1% or less of the whole, a BET specific surface area of 3 m ² / g or less, and a sphericity of 0.91 or less.
It contains a fused spherical silica for liquid sealing in the range of 0.99 to 0.99.

The epoxy resin which is liquid at room temperature is a liquid having one or more epoxy groups in one molecule.
Although not particularly limited, for example, liquid phenol novolak epoxy resin, liquid cresol novolak epoxy resin, liquid bisphenol A epoxy resin, liquid bisphenol AD epoxy resin, liquid bisphenol F epoxy resin, liquid finger ring epoxy resin, 1 , 1-
Liquid epoxy resins such as glycidyl ether of bis (4-hydroxyphenyl) ethane are exemplified. Epoxy resins that are liquid at room temperature can be used alone or in combination of two or more.

As the silicone resin which is liquid at room temperature, for example, the following general formula (1):

[0020]

Embedded image

(Where n is 2 to 10,000 and R ^{1 to} R
Principal ⁸ is a methyl group, the methyl group is a hydrogen atom, a methyl group, a phenyl group, a higher fatty acid residues may be one substituted with an epoxy-containing group or polyoxyalkylene group, and, R ⁴ And R ⁵ may form a cyclic polysiloxane having a methylene group. ), Having a viscosity at 25 ° C. of 2 to 100 Pa · s (1,
A linear, partially hydrogenated, cyclic or modified polysiloxane which is liquid at ordinary temperature and has a pressure of 2 to 500 Pa · s (1,000 poise). Specifically, 2
Examples thereof include polydimethylsiloxane oil having a viscosity of 60 poise at 5 ° C., polydimethylsiloxane oil having a viscosity of 500 poise at 25 ° C., polydimethylsiloxane having a terminal hydroxyl group, and polysiloxane having a terminal vinyl group.

The liquid sealing resin composition of the present invention may contain other optional components in addition to the components (A) and (B). Examples of the optional component include a curing agent for epoxy resin, a curing catalyst, and a coloring agent. When the component (A) is a liquid epoxy resin at room temperature, optional components include tertiary amines, aromatic hydroxyl group-containing tertiary amines such as 4- (imidazo-1-yl) phenol, and diazobicyclo compounds. Curing accelerator, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride,
Curing agents such as methylhexahydrophthalic anhydride, methyltetrahydrophthalic anhydride and isophthalic anhydride are exemplified.

In the liquid sealing resin composition of the present invention, the proportion of the component (B) is 30 to 80% by weight, preferably 30 to 75% by weight.

The fused spherical silica filler for a liquid sealing material of the present invention can be mixed in a high proportion with an epoxy resin or a silicone resin which is liquid at normal temperature, and has a high linear expansion coefficient of the liquid sealing resin composition. Have reliability. Further, the fused spherical silica has a specific particle size distribution, among which,
In particular, since the particles having a particle size of 1 μm or less account for 1% or less of the whole and the sphericity is in the range of 0.91 to 0.99, the liquid sealing resin composition has a high blending amount of the fused spherical silica filler. It has low viscosity and good gap permeability. For this reason, the fused spherical silica filler for liquid sealing material of the present invention,
It is preferably used as a filler for a CSP sealing material having a narrow gap dimension of 24 μm.

[0025]

Next, the present invention will be described in more detail with reference to examples, but this is merely an example and does not limit the present invention.

Examples 1 to 6 and Comparative Examples 1 to _{3 A} nitric acid aqueous solution (HNO ₃ 19.3% by weight) 3,285 was added to a reactor equipped with a stirrer.
g and heated to 70 ° C. Separately, sodium silicate JIS No. 3 (Na ₂ O 7.2% by weight, SiO ₂ 28.5% by weight, SiO ₂ / Na ₂ O
2,100 g in a molar ratio of 3.20) was placed in a container and stirred, and 0.6 g of EDTA was dispersed in a small amount of water, added and dissolved, and further stirred at 70 ° C. for 2 hours. The aqueous solution of sodium silicate containing EDTA was added to the aqueous solution of nitric acid over a period of about 30 minutes.
It was kept at 8080 ° C. After the addition, the reaction slurry was aged by stirring at 80 ° C. for 2 hours. The mother liquor composition at this time was HNO ₃ 5.0
% By weight and 11.1% by weight of NaNO ₃ . After the reaction was completed, the silica precipitate was separated by filtration from the silica precipitate. The precipitate was washed by re-valving in water, and the silica precipitate was separated by filtration again. The separated silica is placed in an acid treatment tank equipped with a stirrer, and water and nitric acid are added thereto to adjust the total amount of the slurry to 3 liters and the concentration of nitric acid in the slurry to 1 N, and 17 g of 35% hydrogen peroxide solution is further added. This silica slurry is stirred for 90
After heating at 3 ° C for 3 hours and acid treatment, the silica was separated by filtration from the slurry, and then re-valve washed with water at room temperature.
Solid-liquid separation and drying were performed, and the mixture was further baked at 900 ° C. for 2 hours. The impurity content in silica is 5 ppm for each impurity element
And low radioactive and high-purity silica having U and Th of 1 ppb or less, respectively, was obtained. Next, the high-purity silica gel was pulverized by a pulverizer such as a ball mill or a jet mill to obtain fused pulverized silica having an average particle diameter of 5 μm. This fused and ground silica is supplied to a melting furnace and melted in an oxygen-LPG mixed flame at a temperature equal to or higher than the melting point of silica. Then, the melted silica is quenched and then collected by a cyclone to obtain fused spherical silica. Was. This fused spherical silica was subjected to a classification treatment as necessary to obtain fused spherical silica having various particle size characteristics.
Table 1 shows the results. Further, the particle diameter, particle size distribution, specific surface area, viscosity (25 ° C. and 50 ° C.) of the mixture mixed with the epoxy resin liquid at room temperature, and gap permeability of the obtained fused spherical silica were measured by the following methods. Table 1 shows the results. In the table, the sphericity “impossible” of Comparative Example 1 refers to a state where measurement is impossible due to aggregation of fine particles.

(Measurement of Average Particle Diameter, Maximum Particle Diameter, and Particle Size of 1 μm or Less) The measurement is carried out by a conventional method using a laser method Microtrac particle size analyzer. (Specific surface area) It is measured by an ordinary method using a BET method monosorb specific surface area measuring device. (Sphericity) It is measured by an ordinary method using an image analyzer Image Pro Plus (manufactured by Planetron). (Gap permeability) As shown in FIG. 1, after a mold having a width of 5 mm, a gap size of 30 μm or 50 μm, and a gap of 18 mm in length was heated to a temperature of 75 ° C., a measurement sample was dropped on one side, and a capillary phenomenon was caused. The time of permeation to one end is measured and displayed in hours (minutes). As a measurement sample, 14 g of an epoxy resin (trade name “Epicoat 815” manufactured by Yuka Shell Co., Ltd.) having a viscosity of 0.98 Pa · s (9.8 O poise) at 25 ° C. and 26 g of fused spherical silica (silica content 65% by weight) were polypropylene. The mixture was weighed into a beaker and uniformly mixed with a glass rod.

[0028]

[Table 1]

[0029]

The fused spherical silica filler for a liquid encapsulant of the present invention can be mixed in a high proportion with an epoxy resin or a silicone resin which is liquid at normal temperature, and can reduce the coefficient of linear expansion of the liquid encapsulating resin composition. Therefore, high reliability can be provided. In addition, even if the amount of the fused spherical silica filler is high, the liquid sealing resin composition has a low viscosity, and therefore has good gap permeability.

[Brief description of the drawings]

FIG. 1 shows a perspective view of a mold used for evaluation of gap permeability.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Measurement sample 2 Cover glass (18 mm x 18 mm) 3 Groove with a gap of 30 µm 4 Groove with a gap of 50 µm 10 Mold

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C08L 83/04 (72) Inventor Tsuyoshi Sakamoto 9-11-1, Kameido, Koto-ku, Tokyo Nippon Kagaku Kogyo Co., Ltd. F-term in headquarters (reference) 4G072 AA25 BB07 GG01 GG02 HH21 JJ13 JJ16 LL06 LL07 MM01 MM02 MM21 MM22 MM23 MM31 RR06 RR12 TT01 TT02 TT06 UU01 UU09 4J002 CD021 CD041 CD061 016 001 014 001 EB16 EC20

Claims (4)

[Claims] A maximum particle size of 24 μm and an average particle size of 2
Particles having a BET specific surface area of 3 m ² / g or less and a sphericity of 0.91 to 0.99. Fused spherical silica for liquid sealing materials. 2. The fused spherical silica for a liquid sealing material according to claim 1, wherein the sphericity is from 0.93 to 0.98. 3. The fused spherical silica for a liquid sealing material according to claim 1, wherein silica gel synthesized by a wet reaction between an alkali silicate and a mineral acid is melted. 4. An epoxy resin or silicone resin which is liquid at room temperature, and (B) particles having a maximum particle size of 24 μm, an average particle size of 2 to 7 μm, and 1 μm or less have a particle size distribution of 1% or less of the whole. A fused spherical silica filler having a BET specific surface area of 3 m ² / g or less and a sphericity in the range of 0.91 to 0.99, wherein the blending amount of (B) is A liquid sealing resin composition characterized by being 30 to 80% by weight of the composition.