AMORPHOUS SILICA POWDER AND RESIN COMPOSITION

Abstract

An amorphous silica powder that is suitable for obtaining a solid sealant that exhibits superior fluidity and filling properties, and a resin composition obtained by using the amorphous silica powder as a filler. An amorphous silica powder is prepared so as to have a modal diameter within the range of 1 to 10 μm in the particle diameter frequency distribution and have a frequency of particles having particle diameters of 0.50 to 1.83 μm of less than 3.0% in the particle diameter frequency distribution.

Claims

1. An amorphous silica powder having a modal diameter within a range of 1 to 10 μm in a particle diameter frequency distribution and having a frequency of particles having particle diameters of 0.50 to 1.83 μm of less than 3.0% in the particle diameter frequency distribution.

2. The amorphous silica powder according to claim 1, having a specific surface area of 1 to 12 m.sup.2/g.

3. The amorphous silica powder according to claim 1, wherein a cumulative oversize distribution of particles having particle diameters of 13 μm or more is 1 mass % or less.

4. The amorphous silica powder according to claim 1, wherein a melting rate is 95% or more.

5. The amorphous silica powder according to claim 1, wherein a total concentration of a uranium element and a thorium element is 10 ppb or less.

Description

EXAMPLES

<Preparation of Amorphous Silica Powder>

[0046] Amorphous silica powders of preparation examples of the present invention were prepared by the following procedure. As a raw material, commercially available amorphous silica was used. This raw material had one peak of the modal diameter in the range of 1 to 10 μm.

[Coarse Powder Classification]

[0047] In this example, the raw material amorphous silica powder was subjected to coarse powder classification in order to exclude large particle diameters. The cumulative oversize distribution of particles having particle diameters of 13 μm or more is shown in Table 2. In the examples, the cumulative oversize distribution of particles having particle diameters of 13 μm or more was 0.0 mass %.

[Fine Powder Classification]

[0048] Next, the cumulative value of particles having. particle diameters of 0.50 to 1.83 μm was adjusted by a method of removing the fine powder side using a precision air classifier. Table 2 shows the cumulative value of particles having particle diameters of 0.50 to 1.83 μm. In the examples, the frequency at the modal diameter within. the range of 1 to 10 μm was 9.3 to 14.3 vol %.

[Blending of Ultrafine Powder]

[0049] Next, an amorphous silica powder having a small particle diameter (ultrafine powder having a median diameter of 0.19, 0.28, or 0.37 μm) was blended with the amorphous silica powder obtained in the steps up to fine powder classification at an internal addition ratio shown in Table 2.

<Preparation of Resin Composition>

[0050] An epoxy resin, a curing agent, an inorganic filler, a curing accelerator, and other materials were mixed at a composition (mass %) shown in Table 1, homogenized, then heated and kneaded with a biaxial roll heated to 80° C., extruded, cooled and solidified, and then pulverized too a predetermined particle size with a pulverizer to prepare a powdery epoxy resin composition in a solid state at normal temperature.

TABLE-US-00001 TABLE 1 Blending ratio Product name Manufacturer (wt %) Content YH-4000HK Mitsubishi Chemical 7.3 Epoxy resin (main material) Corporation MEHC-7800-4S Meiwa Plastic 6.8 Phenol resin (curing material) Industries, Ltd. KBM-403 Shin-Etsu Chemical 0.35 [Silane coupling material (γ- Co., Ltd. glycidoxypropyltrimethoxysilane) TPP Hokko Chemical 0.2 Catalyst (triphenylphosphine) Industry Co., Ltd. Lico-WAX E Clariant Chemicals KK 0.3 Ester wax Spherical 85.0 Amorphous silica powder prepared silica above Total 100.0

<Evaluation of Amorphous Silica Powder and Resin Composition>

[0051] The characteristic values of the obtained amorphous silica powder and resin composition were measured according to the following. The measurement methods are as follows.

[Evaluation of Amorphous Silica Particles]

(1) Specific Surface Area

[0052] The BET theory was applied to the adsorption isotherm measured by the gas adsorption method to determine the specific surface area (BET value) (BET method).

(2) Particle Diameter

[0053] The particle diameter frequency distribution and the particle diameter cumulative distribution of the fine powder were measured using the Coulter method, which is not affected by the sample density.

[0054] The median diameter d (μm) of the ultrafine powder was determined from the BET value measured using the BET method by the following formula for silica particles (density 2.2 g/cm.sup.3)

Median diameter d=6/((BET value)*2.2)  [Mathematical Formula 1]

(3) Melting Rate

[0055] The melting rate in the present invention can be measured from the intensity ratio of a specific diffraction peak by performing X-ray diffraction analysis of a sample with the CuKα line at 2 θ within the range of 26° to 27.5° using a powder X-ray diffractometer. That is, although crystalline silica has a main peak at 26.7°, fused silica does not have a main peak at this position. When fused silica and crystalline silica are mixed, a peak height at 26.7° corresponding to the ratio between the fused silica and the crystalline silica is obtained. Therefore, the mixing ratio of the crystalline silica (X-ray intensity of sample/X-ray intensity of crystalline silica) is calculated from the ratio of the X-ray intensity of the sample to the X-ray intensity of the crystalline silica standard sample, and the melting rate can be determined by the following

Melting rate (%)=(1−mixing ratio of crystalline silica)×100  [Mathematical Formula2]

(4) Concentration of Uranium Element and Thorium Element

[0056] The content of the uranium element and the thorium element was measured using an inductively coupled plasma mass spectrometer (ICP-MS), and the concentration in the powder was calculated.

[Evaluation of Resin Composition]

[0057] Using the prepared powdery epoxy resin composition, transfer molding was performed under the following. conditions to evaluate spiral flow and narrow gap filling properties.

(5) Spiral Flow

(Conditions)

[0058] Mold size: Spiral shape of φ3 mm [0059] Mold temperature: 175° C. [0060] Injection pressure: 65 kgf/cm.sup.2 [0061] Molding time: 90 seconds

(6) Narrow Gap Filling Properties

(Conditions)

[0062] Mold size: 5×60×0.02 mm [0063] Mold temperature: 175° C. [0064] Injection pressure: 65 kgf/cm.sup.2 [0065] Molding time: 90 seconds

[Evaluation Results]

[0066] Table shows preparation conditions (powder classification conditions and composition) of each amorphous silica powder, powder characteristics, and physical property values of flow characteristics (spiral flow and narrow gap filling properties) of a resin composition using each amorphous silica powder.

TABLE-US-00002 TABLE 2 Compar- Compar- ative ative Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 7 ple 8 ple 9 ple 10 ple 11 ple 1 ple 2 Coarse powder ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ ◯ classification Fine powder ◯ ◯ ◯ ◯ ◯ ◯ ◯ — ◯ — ◯ — — classification Average particle 0.14 0.45 0.14 0.10 0.14 0.10 0.10 0.14 — 0.10 0.10 0.10 — diameter of ultrafine powder (μm) Internal addition 28 24 28 28 19 37 19 15 0 19 0 37 0 ratio of ultrafine powder (%) Specific surface 5.9 3.3 6.1 7.5 4.2 10.1 5.0 4.9 2.4 6.1 8.1 9.9 4.7 area (m.sup.2/g) Melting rate (%) 100.0 100.0 99.9 100.0 99.7 98.3 99.8 100.0 99.5 100.0 99.9 96.0 99.0 Concentration of 7.6 31.2 6.9 9.4 2.6 1.7 1.8 4.1 0.9 4.8 8.6 9.4 15.0 uranium + thorium (ppb) Modal diameter 3.9 3.4 3.9 3.9 3.9 3.5 3.9 3.2 3.5 3.2 3.2 3.2 3.9 (μm) Frequency at 11.9 14.3 9.3 12.5 12.7 11.3 12.2 13.6 12.1 13.6 13.0 12.0 9.0 maximum of peak of modal diameter (%) Frequency of 0.0 0.0 0.3 0.0 0.0 0.0 0.0 1.0 0.1 2.0 2.4 4.7 6.7 particles having particle diameters of 0.50 to 1.83 μm (%) Cumulative oversize 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 distribution of particles having particle diameters of 13 μm or more (mass %) Spiral flow (cm) 105 104 98 91 88 77 74 68 66 65 63 57 51 Narrow gap filling 52 55 55 49 48 42 51 41 41 42 43 38 32 property (cm)

INDUSTRIAL APPLICABILITY

[0067] The resin composition containing the amorphous silica powder of the present invention having a modal diameter within the range of 1 to 10 μm in the particle diameter frequency distribution and having a frequency of particles having particle diameters of 0.50 to 1.83 μm of less than 3.0% is the particle diameter frequency distribution as a filler exhibits superior fluidity and filling properties and is therefore suitable for a sealing agent for a semiconductor device.