JP2002121401A - Resin composition for sealing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive resin composition for sealing capable of increasing the content ratio of heat conductive filler without damaging its compatibility and moldability, and capable of preventing crack, etc., caused by difference in heat expansion while securing a high heat conductivity. SOLUTION: This resin composition for sealing is characterized by blending >=60 wt.% first inorganic filler having edge part and >=35 μm particle diameter, <=25 wt.% second inorganic filler removed with the edge part and having <=4 μm particle diameter and further 1.0-2.0 wt.% fibrous material with a thermosetting resin or thermoplastic resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sealing resin composition used as a sealing material for sealing electric parts, electronic parts, semiconductor elements, coils and the like.

[0002]

2. Description of the Related Art In recent years, high-density equipment has been developed mainly in the field of electronic equipment for motors used in automobiles and home appliances.
With the progress of compactness, the dissipation of heat radiated from internal components such as semiconductors and coils has become a major issue. Therefore, a resin composition having high thermal conductivity and high electrical insulation has been required. In order to improve these performances, they have been put to practical use as a thermally conductive sealing material and a thermally conductive adhesive which are highly filled with ceramics such as alumina and silica.

[0003] As the inorganic filler used in these,
It has been said that a resin composition having a crushed shape and a sharp cutting edge is inferior in fillability and moldability and is not sufficient. From these, studies have been made on how to add a large amount of the filler from which the edge portion has been removed. For example, Japanese Patent Application Laid-Open No. 06-224328 discloses that the content of a filler is increased without impairing the fluidity of a resinous material for semiconductor encapsulation, and the thermal expansion, thermal conductivity, moisture absorption resistance and bending strength are improved. For improvement, it has been proposed to finely divide the particle size and finely define the amount thereof.

A similar proposal is disclosed in Japanese Patent Application Laid-Open No. 08-1699.
No. 80 discloses a resin composition or a rubber composition containing an α-alumina powder, particularly an α-alumina powder having high heat conductivity and excellent moldability.
-A resin composition or a rubber composition containing alumina powder has been proposed.

Japanese Patent Application Laid-Open No. 07-82460 discloses that
A sealing epoxy resin composition for high heat conduction of a crystalline silica high filling type containing 80% or more of crystalline silica having good heat dissipation properties, a full mode filling property, and a good sealing moldability epoxy resin for sealing. A composition is provided.

At the same time, in order to ensure thermal reliability,
Studies have been made on a sealing resin composition that matches the coefficient of thermal expansion with built-in components such as semiconductors and coils. For this study, a method of adding amorphous silica and addition of a fiber reinforcing material have been proposed.

[0007] This proposal is disclosed in Japanese Patent Application Laid-Open No. H8-2834.
JP-A-48-48 and the like also use a combination of amorphous silica. Japanese Patent Application Laid-Open No. Hei 10-139928 discloses that a reinforcing fiber is used in combination with an inorganic filler from which an edge has been removed in a proposal considering crack resistance.

[0008]

However, the above-mentioned prior arts of JP-A-08-169980 and JP-A-07-82460 disclose heat-conductive fillers because of the polyhedron or spherical shape with the edge removed. The contact area between comrades is reduced, so it is necessary to perform close packing,
Fillers of many particle sizes are required. Therefore, there was a problem that complicated particle size selection was required, resulting in an expensive composition.

Japanese Patent Application Laid-Open No. 8-283448 discloses that
Since no fiber reinforcement is used, the problem of crack resistance remains due to the factor of low strength. JP-A-10-1399
No. 28 is an inorganic filler from which an edge portion is removed, so that no effect is obtained unless a fiber reinforcing material is added in an amount of 2 wt% or more, and a resin cannot be mixed without a coupling treatment.

The present invention has been made in view of the above situation, and in order to solve the above-mentioned problems, a sealing resin composition according to the present invention has a high thermal conductivity and a high thermal conductivity. An object of the present invention is to provide a sealing resin composition capable of preventing cracks and the like.

[0011]

Means for Solving the Problems To solve the above technical problem, the invention of claim 1 is to provide a thermosetting resin or a thermoplastic resin comprising a first inorganic material having an edge portion and having a particle diameter of 35 μm or more. The filler is blended in an amount of 60 wt% or more, the second inorganic filler having a particle size of 4 μm or less in which the edge portion is removed is blended in an amount of 25 wt% or less, and the fibrous material is added in an amount of 1.0 to 1.0%.
It is a sealing resin composition characterized by being blended at 2.0 wt%.

According to the first aspect of the present invention, by combining a large first inorganic filler having an edge portion and a fine second inorganic filler, the content of the heat conductive filler can be reduced without impairing the mixing property and moldability. Thus, an inexpensive encapsulating resin composition that can increase the rate and can prevent cracks due to a difference in thermal expansion while ensuring high thermal conductivity.

A first particle having an edge portion and having a particle diameter of 35 μm or more;
If the amount of the inorganic filler is less than 60% by weight, the thermal conductivity will be low, and if an inorganic filler whose edge is removed, for example, is added to make up the filler, a filler having a large particle size distribution must eventually be prepared for filling. There is a problem.

If the amount of the second inorganic filler having a particle size of 4 μm or less from which the edge is removed is more than 25% by weight, the viscosity becomes high during kneading of the resin, so that there is a problem that it cannot be produced.
Further, if the amount of the fibrous material is less than 1.0% by weight, there is a problem that the coefficient of thermal expansion at a high temperature becomes high, and if the amount of the fibrous material is more than 2.0% by weight, kneadability at the time of production is reduced. There is a problem that it is necessary to reduce the amount of the conductive filler to be added.

According to a second aspect of the present invention, which is made to solve the above technical problem, the total amount of the first inorganic filler, the second inorganic filler and the fibrous material is more than 70 wt%. The sealing resin composition according to claim 2, wherein:

According to the second aspect of the present invention, an effect that a high thermal conductivity can be obtained by filling a large amount of the thermally conductive filler can be obtained.

If the total amount of the first inorganic filler, the second inorganic filler, and the fibrous material is less than 70% by weight, there is a problem that high thermal conductivity and low thermal expansion cannot be obtained at the same time.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below.
As a component of the inorganic filler as a filler that can be used in the present invention, relatively large particles are substantially composed of particles of the first inorganic filler having an edge portion or a fractured surface. As the first inorganic filler, for example, a green silicon carbide fine powder finely pulverized and sized with a hard green silicon carbide-based abrasive as a base particle, an abrasive exhibiting excellent functions as an abrasive for advanced precision finishing Etc. are used.

The fine particle side has no edge or broken surface.
It consists of inorganic filler particles. The particles of the second inorganic filler are formed into a spherical shape or a particle shape from which edge portions have been removed. As a method of removing the edge portion, the edge portion is removed by a chemical process, a physical process, or the like.

Further, as a fibrous material as a reinforcing material,
0.3μm diameter of glass fiber, potassium phthalate fiber, etc.
A material having a length of 10 to 10 μm and a fiber length of 10 μm to 6 mm is blended together with the first inorganic filler and the second inorganic filler. If the fibrous material is larger than the fine particle diameter, there is a problem that the coefficient of thermal expansion is not stabilized even when 1 to 2 wt% is added. If the fiber length is shorter than 10 μm, the effect of the fiber is lost and the coefficient of thermal expansion increases, and if it is longer than 6 mm, kneading during production cannot be performed.

According to the present invention, a thermosetting resin or a thermoplastic resin is blended with 60 wt% or more of a first inorganic filler having an edge portion and having a particle diameter of 35 μm or more, and a second inorganic filler having a particle size of 4 μm or less after removing the edge portion. When the inorganic filler is blended in an amount of 25 wt% or less and the fibrous material is blended in an amount of 1.0 to 2.0 wt%, the surface contact points of the thermally conductive filler having an edge can be increased, so that the thermal conductivity is maximized. Can be increased. In addition, by using the fine particles from which the edge portions have been removed, it is possible to increase the density of particles generated at the time of molding, so that moldability is not impaired. Further, a sealing resin composition that can prevent cracks due to a difference in thermal expansion while ensuring high thermal conductivity can be obtained.

Examples of the sealing resin composition include resins having high thermal conductivity, liquid resins, and rubber. For example, unsaturated polyester resins, epoxy resins, polyimide resins, silicone resins, phenolic resins, xylene resins, urea resins, melamine resins, urea resins, thermosetting resins such as acrylic resins, preferably when blended,
A resin having a low resin viscosity at the time of molding is used.

Further, various general thermoplastic resins such as polypropylene resin, polyvinyl chloride resin, polyamide resin, polycarbonate resin and polyethylene resin can be freely selected. A resin having a low viscosity is preferred. The sealing resin composition may be an elastic composition such as a natural rubber or an elastomer.

The first resin used in the encapsulating resin composition of the present invention.
1, The second inorganic filler is oxide, nitride, metal such as gold, copper, carbon, diamond, etc., and also uses ceramics, surface-treated metal powder or carbon powder that removes conductivity. May be.

Further, an internal release agent,
Flame retardants, dispersants, defoamers, curing catalysts, colorants, and the like can be added within a range that does not impair the present invention.

The method of mixing the inorganic filler in the resin composition for sealing in the present invention is not particularly limited, and the mixing is carried out by using a commonly used mixer such as a roll, a kneader, a planetary stirrer, an extruder, or the like. It can be compounded.

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples. The measurement used in the present invention was performed as follows.

Confirmation of the particle size was observed with a scanning electron microscope. The thermal conductivity was measured by a rapid thermal conductivity meter (Kemtherm QTM-D3) manufactured by Kyoto Electronics Industry Co., Ltd.

[0029]

(Example 1) Silicon carbide (trade name: GC # 400) manufactured by Showa Denko KK was prepared, and a first inorganic filler having an average particle size of 37 μm was obtained by a separation treatment. This silicon carbide is called Green Densic (trade name) GC, and is a green silicon carbide fine powder that is finely ground and sized using an extremely hard green silicon carbide-based abrasive as a base particle, and is excellent as an abrasive for high precision finishing. It is an abrasive material that demonstrates its functions.

Further, silicon carbide (trade name: GC-4000F) manufactured by Yakushima Electric Works, Ltd. was prepared. The average particle size of the inorganic filler is 2.8 μm.

As the resin, an unsaturated polyester resin, Ester RT400 manufactured by Mitsui Chemicals, Inc. was prepared. In addition, T-butyl perbenzoate was used as a curing agent, polystyrene was used as a low-shrinking agent, and zinc stearate was used as an internal release agent.

Finally, as a fiber reinforcing material, a length of 6 mm and a diameter of 1
3 μm glass fibers were prepared.

Each was mixed at the compounding ratio shown in Table 1.

Using the prepared resin compound 作 製, a steel block (15 mm × 15 mm × 100 mm) was
After being inserted into the center of a × 200 mm casting jig, it was cured by heating at a mold temperature of 150 ° C. and 200 MPa for 10 minutes to prepare a test piece for heat cycle. 100mm × 15 at the same time
A test plate of 0 mm × t (thickness) 15 mm for measuring thermal conductivity and thermal expansion coefficient was prepared. For the measurement of the coefficient of thermal expansion, a test piece having a diameter of 4 mm and a length of 8 mm was cut out from a test plate, and RT
(Room temperature) Under two conditions of 25 ° C. to 50 ° C. and 130 ° to 160 ° C., the test piece was heated at a rate of temperature increase of 5 ° C./min by TMA measurement (Thermomechanical analysis: thermal dilatometer measurement), and its length was measured. The change was measured.

The test plate was subjected to a temperature range of -40 to 185 ° C. for 30 minutes each, and the presence or absence of cracks after 100 cycles was confirmed.

Example 2 Each raw material was prepared in the same manner as in Example 1, except that silicon carbide (trade name: GC # 240) manufactured by Showa Denko KK was prepared and averaged by a separation treatment. A filler having a particle size of 83 μm was obtained. Other components are shown in Table 1.
Were mixed in the mixing ratio described in (1).

Example 3 Each raw material was prepared in the same manner as in Example 1, and mixed at the mixing ratio shown in Table 1.

The same performance was confirmed as in Example 1.

Example 4 Each raw material was prepared in the same manner as in Example 1, and mixed at the mixing ratio shown in Table 1.

The same performance as in Example 1 was confirmed.

Example 5 In the same manner as in Example 1, each raw material was prepared and mixed at the mixing ratio shown in Table 1.

The same performance as in Example 1 was confirmed.

Comparative Example 1 Each raw material was prepared in the same manner as in Example 1, and mixed at the mixing ratio shown in Table 1.

The same performance as in Example 1 was confirmed.

Comparative Example 2 Each raw material was prepared in the same manner as in Example 1, and mixed at the mixing ratio shown in Table 1.

Tables 1 and 2 show the evaluation results.

[0047]

[Table 1]

[Table 2] Here, “good” in the material production in Table 2 means a state in which the filler component is sufficiently wet with the resin, and “bad”.
The term refers to a state in which a filler whose resin is not wet exists. In the moldability of the molded plate, "good" means filling,
It was evaluated that there was no particular problem such as demolding. "Defective" refers to a state in which the occurrence of a defective filling portion such as a nest or a void and removal from the mold cannot be performed when observed with a microscope at a magnification of 100 times.

In the above Examples, the actual measured values of the thermal conductivity of the experimental blends were as shown in Table 2 for Examples 1 to 5 in that the material productivity and the formability of the molded plate were good, as shown in Table 2. As a result of observing the occurrence of cracks after 100 cycles of 30 minutes each, there were no cracks in the steel insert, copper insert, and aluminum insert, and the coefficient of thermal expansion was small.

On the other hand, Comparative Example 1 has a large coefficient of thermal expansion at high temperatures. Comparative Example 2
As a result, nests and voids were generated, and the result was that the thermal conductivity was slightly lowered due to the influence.

From the above results, the present invention was able to secure crack resistance while securing high heat conduction. The resin composition of the present invention is an electrical insulating material that has improved reliability such as thermal cracking in a product environment as well as thermal conductivity. It is suitable for applications such as agents and sheet materials.

[0051]

According to the present invention, a thermosetting resin or a thermoplastic resin is blended with 60 wt% or more of a first inorganic filler having an edge portion and having a particle size of 35 μm or more, and having a particle size of 4 μm or less after removing the edge portion. 25 wt% of the second inorganic filler
The following is blended, and the fibrous material is further added to 1.0 to 2.0 wt.
%, So that the content of the thermally conductive filler can be increased without impairing the mixability and moldability, and the thermal expansion while ensuring high thermal conductivity. An inexpensive sealing resin composition that can prevent cracks and the like due to the difference.

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Claims (2)

[Claims] 1. A thermosetting resin or a thermoplastic resin,
60 wt% or more of the first inorganic filler having an edge portion and having a particle diameter of 35 μm or more is compounded, and 25 wt% or less of a second inorganic filler having a particle size of 4 μm or less from which the edge portion has been removed. A resin composition for encapsulation, wherein the composition is contained in an amount of up to 2.0 wt%. 2. The sealing resin composition according to claim 2, wherein the total amount of the first inorganic filler, the second inorganic filler, and the fibrous material is 70% by weight or more.