WO2005033216A1

WO2005033216A1 - Coated magnesium oxide powder capable of being highly filled and method for production thereof, and resin composition comprising the powder

Info

Publication number: WO2005033216A1
Application number: PCT/JP2003/015954
Authority: WO
Inventors: Toshio Kiyokawa; Kaori Yamamoto; Masaaki Kunishige
Original assignee: Tateho Chemical Industries Co., Ltd.
Priority date: 2003-10-03
Filing date: 2003-12-12
Publication date: 2005-04-14
Also published as: TWI262897B; JP4237182B2; TW200513437A; AU2003289060A1; JPWO2005033216A1

Abstract

A spherical coated magnesium oxide powder, characterized in that it is surface-coated with a double oxide and has an angle of repose of 55 degree or less and a tap density of 1.65 g/ml or more; a resin composition comprising the powder; and an electronic device using the resin composition. The spherical coated magnesium oxide powder is excellent in the resistance to moisture and also is excellent in fluidity and in the capability of being filled in a high proportion when used as a filler into a resin.

Description

Specification

TECHNICAL FIELD The present invention relates to a highly-filled coated magnesium oxide powder and a resin composition containing the powder.

The present invention relates to a coated magnesium oxide powder excellent in moisture resistance and excellent in filling when used as a filler, and a resin composition excellent in fluidity containing the coated magnesium oxide powder. '' Background technology

Electronic devices are composed of electronic components such as laminates, printed wiring boards, and multilayer wiring boards. In electronic components, a resin composition is usually used for a pre-preda, a spacer, a sealant, an adhesive sheet, and the like, and a resin composition is required to have various performances or characteristics. For example, recent trends include the mounting of high-capacity power elements and high-density mounting in electronic devices, and as a result, the resin composition and its applied products are required to have better heat dissipation and moisture resistance than before. ing.

Conventionally, as a filler used for a resin composition for semiconductor encapsulation, silicon dioxide (hereinafter, referred to as silica) and aluminum oxide (hereinafter, referred to as alumina) have been used. The thermal conductivity of silica is low, and the heat dissipation is not enough to cope with the increase in the amount of heat generated by high integration, high power, high speed, etc., causing problems in the stable operation of semiconductors, etc. . On the other hand, the use of alumina, which has higher thermal conductivity than silica, improves heat dissipation, but alumina has a high hardness, which causes a problem in that kneaders, molding machines, and molds will be severely worn. .

Therefore, magnesium oxide, which has an order of magnitude higher thermal conductivity than silica and about the same thermal conductivity as alumina, is being studied as a material for resin fillers for semiconductor encapsulation. However, magnesium oxide powder has higher hygroscopicity than silica powder. Therefore, when magnesium oxide powder is used as a resin filler for semiconductor encapsulation, problems such as generation of cracks due to volume expansion of the filler and reduction of thermal conductivity due to hydration of the absorbed water and magnesium oxide. Had occurred. Therefore, it is necessary to provide moisture resistance to magnesium oxide powder used as a resin filler for semiconductor encapsulation. Has been a major issue in guaranteeing long-term stable operation of the.

As methods for improving the moisture resistance of magnesium oxide powder, JP-A-2003-34522 and JP-A-2003-34525 disclose aluminum salt or cake. The magnesium compound powder is mixed with the magnesium oxide powder, the solid content is filtered off, dried, and calcined, so that the surface of the magnesium oxide powder is coated with a coating layer containing aluminum or a double oxide of silicon and magnesium. A method for producing a coated magnesium oxide powder is disclosed.

Although the coated magnesium oxide powder obtained by these methods has improved moisture resistance, since the powder particles have an angular shape, the filling property of the resin is low, and the flow of the obtained resin composition is further reduced. There is a problem that the property is low.

On the other hand, Japanese Patent No. 2590491 discloses that alumina and / or sily particles are added to magnesium oxide powder, and this is granulated using a spray drier to obtain spherical granules. Thereafter, a method for producing a magnesium oxide-based material is disclosed in which at least a part of the granulated material is melted without breaking a strong granulated state, and then the granulated material is rapidly cooled.

This method aims at improving the moisture resistance of the magnesium oxide particles.However, since the particles are granulated using a spray drier, the obtained spherical granules are aggregates of particles, that is, porous materials, and are formed into resin. High filling is expected to be difficult.

An object of the present invention is to provide a coated magnesium oxide powder that solves the above-mentioned problems, has excellent moisture resistance, and has excellent filling properties when used as a filler, and can be highly filled into a resin. . Another object of the present invention is to provide a resin composition containing the coated magnesium oxide powder and having excellent moisture resistance, thermal conductivity and fluidity, and an electronic device using the resin composition. Disclosure of the invention

In order to achieve the above object, the present inventor focused on the angle of repose as a parameter indicating the fluidity of the powder, and the tap density as a parameter indicating the filling property, while conducting various studies. Excellent flowability and filling when within a certain range It has been found that a powder having excellent flowability can be obtained by using the powder.

That is, according to the present invention, the surface is covered with the double oxide, oxide coated magnetic Shiumu powder repose angle of ^{5 5} degrees or less, and the tap density is equal to or is 1. 6 5 g / m 1 or more Is provided.

Further, according to the present invention, there are provided a resin composition containing the above-mentioned coated magnesium oxide powder as a filler, and an electronic device using the resin composition. BEST MODE FOR CARRYING OUT THE INVENTION

Coated magnesium oxide powder

The coated magnesium oxide powder in the present invention has a surface coated with a double oxide, an angle of repose of 55 degrees or less, and a tap density of 1.65 g Zm 1 or more.

Here, the angle of repose is one of the characteristic values for calculating the fluidity index of so-called Carr, which is an index for comprehensively evaluating the fluidity of powder proposed by R.L.Carr. The fluidity of the powder can be evaluated by the angle of repose. Specifically, it refers to the angle between the generatrix and the horizontal plane of the cone formed when the powder is gently dropped on a horizontal surface using a funnel.

By setting the angle of repose to 55 degrees or less, the flowability of the powder is improved, and as a result, the flowability of the resin composition containing the powder can be improved. This angle of repose is preferably 50 degrees or less.

The tap density is an index for evaluating the filling property of powder, and refers to the mass of powder per unit volume when a powder sample is placed in a container of known volume and tapped a specified number of times from a certain height. The tapping density is 1.65 g 1 or more, and more preferably 1.80 g / m 1 or more.

The surface of the coated magnesium oxide powder of the present invention is coated with a double oxide. The composite oxide covering the surface of the magnesium oxide powder preferably contains magnesium and one or more elements selected from the group consisting of aluminum, iron, silicon and titanium. By coating the surface with this double oxide, acid Moisture resistance of magnesium fluoride powder is greatly improved.

As double oxides, false Terai Doo _{_{(Mg 2 S i 0 4)}} , spinel (A l ₂ Mg 0 ₄ Magnesium Blow wells (F e ₂ Mg0 _4), magnesium titanate (Mg T I_〇 ₃₎ and the like Can be.

The content of the double oxide used in the present invention, that is, the ratio of the double oxide on the surface to one particle is preferably from 5 to 50 mass%, more preferably from 10 to 40 mass%. When the content of the double oxide is within the above range, the surface of the magnesium oxide powder is completely covered with the double oxide, so that the moisture resistance is greatly improved, and the thermal conductivity of the resin composition after filling is further improved. It is also high, and can exhibit sufficient effects as a thermal conductive filler.

The average particle diameter of the coated magnesium oxide powder of the present invention is preferably ^{5 X 1 0- 6 ~5 0 0} X 10- 6 m, 10 X 10-6~: I 00 X 10 one ⁶ m is more preferable. Further, the BET specific surface area is preferably 5.0 X 10 ³ m ² / kg or less, more preferably 1 X 10 ³ m ² // kg or less.

The coated magnesium oxide powder having a repose angle of 55 degrees or less and a tap density of 1.65 gZm 1 or more according to the present invention has a high temperature in the presence of a compound forming a double oxide on the surface of the magnesium oxide powder. By melting the coated magnesium oxide powder, it can be produced by spheroidizing the coated magnesium oxide powder. For example, powder is melted by passing it through a high-temperature flame, and spheroidized by surface tension.

Further, it is also possible to manufacture by sintering at a sintering temperature equal to or lower than the melting point of the coating material in a state where the compound forming the complex oxide is present on the surface of the magnesium oxide powder. Since the coated magnesium oxide powder obtained by this method is not always spherical, a powder satisfying the fluidity index and oil absorption of the present invention at the same time is produced by mixing powders having different particle diameters.

The compound used to form the double oxide is preferably at least one compound selected from the group consisting of an aluminum compound, an iron compound, a silicon compound and a titanium compound. The form of the compound is not limited, but nitrates, sulfates, chlorides, oxynitrates, oxysulfates, oxychlorides, hydroxides and oxides are used. The amount of these compounds in the magnesium oxide powder is finally obtained The content of the double oxide in the coated magnesium oxide powder is preferably determined to be 5 to 50 mass%.

Crystallite size of the magnesium oxide powder used in the present invention is preferably 5 0 X 1 0- ⁹ m or more. Crystallite diameter 5 0 X 1 0- ⁹ m or more oxidation Maguneshiu. Beam powder finer powder has low reactivity compared to, to uniformly adsorb Kei-containing compound or the like on the surface of the magnesium oxide powder Therefore, the composite oxide covering the surface of the magnesium oxide powder becomes uniform, and the water resistance is improved.

The crystallite diameter used in the present invention is a value calculated by the Scherrerr formula using the X-ray diffraction method. In general, one particle is a polycrystal composed of a plurality of single crystals, and the crystallite diameter indicates an average value of the size of the single crystal in the polycrystal.

The purity of the magnesium oxide powder is not particularly limited, and is preferably determined according to the application. For example, in order to satisfy the insulation properties of the electronic component, the purity is preferably 90% or more, and more preferably 95% or more. The magnesium oxide powder having the characteristics of the present invention can be produced by a known method, for example, an electrofusion method or a sintering method. Resin composition containing coated magnesium oxide powder

According to the above-described production method, a coated magnesium oxide powder having a high resin filling property can be easily obtained at low cost while maintaining moisture resistance and thermal conductivity. Further, the resin composition filled with the coated magnesium oxide powder thus obtained has good fluidity and improves moldability.

The resin composition of the present invention is obtained by adding the above-mentioned coated magnesium oxide powder to a resin.

In that case, the coated magnesium oxide powder of the present invention can be surface-treated with a silane-based coupling agent, a titanate-based coupling agent, or an aluminate-based coupling agent, if necessary, to further improve the filling property. Can be.

Examples of the silane coupling agent include vinyl trichlorosilane, vinyl oxysilane, glycidoxypropyl trialkoxysilane, methacryloxypropylmethyldialkoxysilane, and the like. Examples of titanate-based coupling agents include isopropyltriisostearoyl titanate, tetraoctylbis (ditridecylphosphate) titanate, and bis (dioctylpyrophosphate). The resin used in the resin composition of the present invention is not particularly limited, and is a thermosetting resin such as an epoxy resin, a phenol resin, a polyimide resin, a polyester resin, or a silicone resin, a polycarbonate resin, an acrylic resin, or a polyphenylene sulfide resin. And thermoplastic resins such as fluororesins. Of these, epoxy resins, silicone resins, and polyphenylene sulfide resins are preferred. If necessary, a curing agent and a curing accelerator can be added.

Epoxy resins include bisphenol A epoxy resin, novolak epoxy resin, bisphenol F epoxy resin, brominated epoxy resin, orthocresol novolak epoxy resin, glycidyl ester resin, glycidylamine resin, and heterocyclic epoxy. Resins and the like.

Examples of the phenol resin include novolak phenol resin and resole phenol resin.

Examples of the silicone resin include a millable silicone rubber, a condensation type liquid silicone rubber, an addition type liquid silicone rubber, and a UV curing type silicone rubber, and the addition type liquid silicone rubber is preferable. Further, either one-pack type or two-pack type silicone rubber may be used, but two-pack type silicone rubber is preferable.

The resin composition of the present invention may contain a filler in addition to the above coated magnesium oxide powder. The filler is not particularly limited, and examples thereof include fused silica and crystalline silica. If necessary, a release agent, a flame retardant, a coloring agent, a low stress imparting agent, and the like can be appropriately compounded.

The electronic device of the present invention uses the above resin composition for a part thereof, and has excellent heat dissipation and moisture resistance. Examples of the electronic device include a resin circuit board, a metal base circuit board, a metal-clad laminate, and a metal-clad laminate with an inner circuit. Examples of the use of the resin composition of the present invention for the above electronic device include a semiconductor encapsulant, an adhesive or an adhesive sheet, a heat dissipation sheet, a heat dissipation spacer or a heat dissipation grease. In order to manufacture the above-mentioned substrate or the like using the resin composition of the present invention, a paper base / glass substrate is immersed in the resin composition of the present invention, dried by heating and cured to a B stage, Resin cloth, resin paper, etc.)

Also, a resin circuit board, a metal-clad laminate, a metal-clad laminate with an inner layer circuit, and the like can be manufactured using this pre-preda. For example, for a metal-clad laminate, a pre-preda is stacked according to the substrate thickness, a metal foil is placed, sandwiched between molds, inserted between hot plates of a press machine, and subjected to predetermined heating and pressing to form a laminate. Then, the four sides of the formed laminated board are cut, and the appearance is inspected to manufacture.

Further, the resin composition of the present invention can be mixed with another base material and used as a base material in the form of a composite material such as glass epoxy or Teflon epoxy. The resin composition of the present invention can be used as a sealing material. The sealing resin is a resin material used for packaging for protecting the semiconductor chip from external factors such as mechanical, thermal stress and humidity. The performance of the formed package is indicated by the thermal conductivity and weather resistance of the cured resin.

The resin composition of the present invention can be used as an adhesive. The adhesive refers to a substance used for bonding two objects, and the material of the adherend is not particularly limited. The adhesive is temporarily given fluidity when applied or engaged on the surface of the adherend, and loses fluidity and solidifies after bonding. For example, a heat-sensitive adhesive such as a solvent adhesive, a pressure-sensitive adhesive, or an adhesive sheet, or a reactive adhesive can be used. When the resin composition of the present invention is used as an adhesive, the thermal conductivity and weather resistance after bonding are indicated by the thermal conductivity and weather resistance of the cured resin. -.

Further, a metal-based circuit board can be manufactured by using the resin composition of the present invention as an adhesive. The metal-based circuit board is manufactured by applying an adhesive on a metal plate, laminating metal foils when the adhesive is in the B-stage state, performing predetermined heating and pressing, and integrating them.

Further, the resin composition of the present invention can be used as a heat dissipating material. Examples of the heat dissipating material include a heat dissipating sheet, a heat dissipating spacer, and a heat dissipating grease. The heat dissipation sheet is used to remove heat generated from heat-generating electronic components and electronic devices. Air-insulating heat conductive sheet, manufactured by filling silicone rubber with a heat conductive filler, and used mainly by attaching to heat radiating fins or metal plates. The heat dissipation grease is the same as the heat dissipation sheet except that silicone oil is used instead of silicone rubber. The heat-dissipating spacer is a thickness that fills the space between the heat-generating electronic components, the electronic device, and the case to directly transfer the heat generated from the heat-generating electronic components, the electronic device to the case of the electronic device. Is a solidified silicone having Example

EXAMPLES The present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples.

1. coated magnesium oxide powder

Synthesis example 1

Crystallite diameter 58. 3 X 1 0_ ⁹ assembly a is magnesium oxide Powder of single crystals of m to (Tateho Chemical Industries Co., Ltd. KMAO- H), using an impact-type dust碎機, particle size 100 X 1 It was ground to below 0- ⁶ m. Fumed silica (purity: 99.9% or more, specific surface area: 200 ± 20 m ² / g) is wet added to magnesium oxide so that the mixing ratio becomes 10 mass%, and the mixture is stirred at 400 to 500 rpm for 600 s. Mixed. After stirring and mixing, the cake obtained by filtration and dehydration was dried at 423 K using a dryer. The dried cake was crushed by a sample mill to adjust the particle size to about the same as the raw material magnesium oxide powder, to obtain a coated magnesium oxide powder.

Synthesis example 2

'Crystallite diameter 58. 3 X 1 0- ⁹ assembly a is magnesium oxide Powder of single crystals of m to (Tateho Chemical Industries Co., Ltd. KMAO- H), using an impact-type dust碎機, particle size 7 X 10-ground to less than ⁶ m. Fumed silica (purity: 99.9% or more, specific surface area: 200 ± 2 Om ² Zg) is wet added to magnesium oxide so that the mixing ratio becomes 10 mass%, and 600 at 400 to 500 rpm. The mixture was stirred and mixed. After stirring and mixing, the cake obtained by filtration and dehydration was dried at 423 K using a dryer. The dried cake was crushed by a sample mill to adjust the particle size to about the same as the raw material magnesium oxide powder, to obtain a coated magnesium oxide powder. Synthesis example 3

A coated magnesium oxide powder was obtained in the same manner as in Synthesis Example 1 except that the mixing ratio of the fumed silica force was 3 mass%.

Synthesis example 4

A coated magnesium oxide powder was obtained in the same manner as in Synthesis Example 1 except that the mixing ratio of the fumed silica was 30 mAss%.

Synthesis example 5

Crystallite diameter 58. 3 X 1 0- ⁹ assembly a is magnesium oxide Powder of single crystals of m to (Tateho Chemical Industries Co., Ltd. KMAO- H), using an impact-type dust碎機, particle size 1 00 X 10-ground to less than ⁶ m. 4% aqueous aluminum nitrate solution (manufactured by Kanto Chemical Co., Ltd. Ltd. special grade reagent), in terms of A 1 ₂ 0 _3, wet-added to the mixing ratio to magnesium oxide is 10 mass%, 400 to 500 rp For 600 s with stirring. After stirring and mixing, the mixture was filtered to form a cake. After removing residual aluminum nitrate, the cake was sufficiently washed with water and dehydrated, and dried at 423 K using a dryer. Dried. The dried cake was crushed with a sample mill to adjust the particle size to about the same as the raw material magnesium oxide powder, to obtain a coated magnesium oxide powder.

Synthesis Example 6

Instead of aluminum nitrate, iron nitrate aqueous solution, in terms of F e ₂ 〇 _3, except that the mixing ratio against oxidation Ma Guneshiumu were blended so that 15 m ass%, in the same manner as in Synthesis Example 4 A coated magnesium oxide powder was obtained.

Example 1

The powder prepared in Synthesis Example 1 was fed to a high temperature flame formed by burning of liquefied propane gas and oxygen, was melt-spheroidizing treatment was coated with false Terai Doo (Mg ₂ S i 0 ₄₎ Spherical To obtain a coated magnesium oxide powder.

Example 2

The powder produced in Synthesis Example 1 was calcined in air at 1723 K for 3600 s, and then re-crushed in a sample mill to adjust the particle size to the same level as the raw material magnesium oxide powder. (Mg ₂ Si 0 ₄ ) coated magnesium oxide powder I got the end.

On the other hand, the powder prepared in Synthesis Example 2 was treated in the same manner as above to adjust the particle size to the same level as the raw material magnesium oxide powder, and coated with forsterite (Mg ₂ Si ₄ ). A coated magnesium oxide powder was obtained.

The coated magnesium oxide powder obtained from Synthesis Example 1 and the coated magnesium oxide powder obtained from Synthesis Example 2 were mixed at a mass ratio of 7: 3. Example 3

Except that the powder prepared in Synthesis Example 3 was used, a melting process was performed in the same manner as in Example 1 above, and a spherical coated magnesium oxide powder coated with forsterite (Mg ₂ Si ₄ ) was obtained. Obtained.

Example 4

Except that the powder prepared in Synthesis Example 4 was used, a melting and spheroidizing treatment was performed in the same manner as in Example 1 above, and a spherical coated magnesium oxide coated with forsterite (Mg ₂ Si ₄ ) was used. A powder was obtained.

Example 5

Except for using the powder prepared in Synthesis Example 5 performs molten-spheroidizing treatment in the same manner as in Example 1 to obtain a coated oxide Maguneshiumu powder spherical coated with spinel (A 1 ₂ Mg 0 ₄₎ Was.

Example 6

Except for using the powder prepared in Synthesis Example 6 performs molten 'spheroidizing treatment in the same manner as in Example 1, magnesium Blow wells (F e ₂ Mg_〇 ₄₎ coated oxide Maguneshiumu powder coated spherical Got.

Comparative Example 1

The powder obtained in Synthesis Example 1 was calcined in air at 1723 K for 3600 s, and then crushed again with a sample mill to adjust the particle size to about the same as the raw material magnesium oxide powder. (Mg ₂ Si ₄ ) to obtain a coated magnesium oxide powder.

Comparative Example 2

Magnesium oxide powder is formed by combustion of liquefied propane gas and oxygen. The powder was supplied into a warm flame to obtain a magnesium oxide powder having an uncoated surface.

Evaluation test

The content of coated double oxide, angle of repose, tap density, BET specific surface area, average particle size, and moisture resistance of the coated magnesium oxide powder samples obtained in Examples 1 to 6 and Comparative Examples 1 and 2 described above. Each item was measured and the results are shown in Table 1. The measurement method for each item is shown below.

Content of double oxide on powder surface: Using a scanning X-ray fluorescence spectrometer “ZSX-100e” (manufactured by Rigaku Denki Kogyo Co., Ltd.), measure the content of elements contained in the powder sample and perform double oxidation. Was converted to the content of the substance.

Angle of repose: Using a powder property measurement device “Powder Tester PT-N” (manufactured by Hosokawa Micron Corporation), vibrating a standard sieve (opening 7 10 μΠ _Π ) and dropping the powder sample through a funnel, using the injection method. The angle of repose (degree) was measured.

Tap density: Using a powder property measurement device "Powder Tester I-II" (manufactured by Hosokawa Micron Corporation), put a powder sample in a 100 ml container, tap it 180 times from a certain height, and harden it with the impact of tapping. After that, the tapping density (g / ml) was measured.

BET specific surface area: The specific surface area of the powder sample was measured by a gas adsorption method using a flow-type specific surface area measurement device “Flow Soap 1 1300” (manufactured by Shimadzu Corporation).

Average particle size: Laser diffraction and scattering method

Using HRA (manufactured by Nikkiso Co., Ltd.), the volume average particle size of the powder sample was measured. Moisture resistance test: A sample 5 X 10 ³ kg obtained was stirred for 2 hours in boiling water 100 X 10_ ⁶ m ³ temperature 373 K, by measuring the mass increase rate was evaluated moisture resistance. Double oxide Coated magnesium oxide

Content Repose angle Evening density Average particle size BET specific surface area Mass increase rate Type

(mass%) (degree) (g / ml) (10-¾) (10 ³ mVkg) (mass¾) Example 1 Mg ₂ Si0 ₄ 17.49 52.1 1.863 21.01 0.75 2.97

Mg ₂ Si0 ₄

Example 2 18.14 48.5 2.006 17.00 1.10 3.39

(Mixed powder)

Example 3 Mg ₂ Si0 ₄ 6.56 50.7 1.747 20.24 0.54 4.12 Example 4 Mg ₂ Si0 ₄ 48.52 48.1 1.994 21.77 0.83 1.37 Example 5 Al ₂ Mg0 ₄ 21.76 47.4 1.701 20.45 0.78 2.77 Example 6 Fe ₂ Mg0 ₄ 21.00 48.2 1.840 20.21 0.31 1.08 Comparative Example 1 Mg ₂ Si0 ₄ 18.45 54.5 1.611 20.45 0.48 3.19 Comparative Example 2 ― 1 46.4 1.930 21.09 0.81 7.34

2. Resin composition

Example 7

To the sample powder prepared in Example 1, 1.0 mass% of epoxysilane was added, and the powder was subjected to surface treatment by stirring and mixing for 600 s, and then dried at 420 K for 720 s. The obtained sample (560 parts by weight) was mixed with an ortho-cresol novolak epoxy resin.

63 parts by weight, 34 parts by weight of nopolak phenol resin, 1 part by weight of triphenylphosphine and 2 parts by weight of carnapa wax were mixed and pulverized for 600 s using a crusher. Thereafter, the mixture was kneaded using a two-roll mill at 3773 K for 300 s, and then the kneaded material was further pulverized to a size of 10 mesh or less. A wret was made. This pellet was transfer-molded at 7 MPa, 448 K for 180 s, and the spiral flow was measured.

Further, the pellet was transfer molding with a 4 4 8 K in 1 8 0 s, 7 MP a , then performs a 1 8 X 1 0 ³ s between Posutokiyua at 4 5 3 K, φ 5 0 mm X t 3 mm Was obtained.

Example 8

Spiral flow was measured in the same manner as in Example 7 except that a mixed powder of coated magnesium oxide powders having different particle sizes prepared in Example 2 was used, and a molded product was obtained.

Example 9 '

Spiral flow was measured in the same manner as in Example 6 except that the spherical coated magnesium oxide powder produced in Example 3 was used, and a molded product was obtained.

Example 1 0

Spiral flow was measured in the same manner as in Example 6 except that the spherical coated magnesium oxide powder produced in Example 4 was used, and a molded product was obtained.

Example 11

Spiral flow was measured in the same manner as in Example 6 except that the spherical coated magnesium oxide powder produced in Example 5 was used, and a molded product was obtained.

Example 1 2

Except that the spherical coated magnesium oxide powder prepared in Example 6 was used Spiral flow was measured in the same manner as in Example 6 to obtain a molded body.

Comparative Example 3

The spiral flow was measured in the same manner as in Example 7 except that the sample prepared in Comparative Example 1 was used, and a molded product was obtained.

Comparative Example 4

Spiral flow was measured in the same manner as in Example 7, except that alumina powder was used instead of magnesium oxide powder, to obtain a molded body.

Example 1 3

To the sample powder prepared in Example 1 was added 1.0% of butyltrimethoxysilane, and the mixture was stirred and mixed for 600 s to perform a surface treatment of the powder.

It was dried for 720 s. 450 parts by weight of the obtained sample was kneaded with 100 parts by weight of a two-component RTV silicone rubber for 300 seconds using a two-roll mill. Next, 5 parts by weight of a platinum catalyst was added and kneaded for 600 s using a two-roll mill to prepare a compound, and the viscosity was measured under the following conditions. This was press-molded at 3933 K for 600 s and 5 MPa to obtain a molded product of <) 50 111111 c 3 111111.

Example 14

The viscosity was measured in the same manner as in Example 13 except that the mixed sample powder produced in Example 2 was used, and a molded product was obtained.

Comparative Example 5

The viscosity was measured in the same manner as in Example 13 except that the sample powder produced in Comparative Example 1 was used, and a molded product was obtained.

Comparative Example 6

The viscosity was measured in the same manner as in Example 13 except that the alumina powder was used instead of the magnesium oxide powder, to obtain a molded body.

Evaluation test

Spiral flow or viscosity of the resin composition obtained in each of Examples 7 to 14 and Comparative Examples 3 to 6 (an appropriate measurement method was selected depending on the state of the resin at room temperature). The thermal conductivity, moisture resistance, and appearance of the molded article of the resin composition after the moisture resistance test were measured, and the results are shown in Table 2. The evaluation method for each of the above items is as follows. Spirano reflow: Measured according to EMM I-I-66.

Viscosity: The viscosity was measured using a rheometer "VAR-50" (manufactured by REOLOG ICA), and the value of S hearrate was set to 1 s- ¹ .

Thermal conductivity: The thermal conductivity of the molded body was measured by a laser flash method using a thermal constant measuring device “TC 3000” (manufactured by Vacuum Riko Co., Ltd.).

Moisture resistance test: The molded body was stored in a thermo-hygrostat set at a temperature of 358 K and a humidity of 85% for 7 days, and the moisture absorption was measured. The appearance was visually observed.

Fluidity of resin composition Evaluation test of molded article Double oxide Resin Spiral Viscosity Thermal conductivity Moisture absorption Moisture resistance test Appearance after flow (m) (Pa · s) (W / m) (mass¾) Example 7 Mg ₂ Si0 ₄ epoxy resin 0.507 - 3.11 0.18 No change example 8 Mg ₂ Si0 ₄ epoxy resin 0.468 -. 3.12 0.16 No abnormality example 9 Mg ₂ Si0 ₄ epoxy resin 0.448 - 3.25 0.20 No change example 10 Mg ₂ Si0 ₄ epoxy resin 0.653 -. 3.03 0.11 No abnormality example 11 Al ₂ Mg0 ₄ epoxy resin 0.535 - 3.12 0.15 No change example 12 Fe ₂ Mg0 ₄ epoxy resin 0.492 - 3.15 0.14 ¾ atmospheric None Comparative example 3 Mg ₂ Si0 ₄ epoxy resin 0.343 - 3.18 0.17 No abnormality Comparative example 4 _w Epoxy resin 0.502 ― 2.78 0.15 No abnormality Example 13 Mg ₂ Si0 ₄ Silicone rubber 471 2.20 0.20 No abnormality Example 14 Mg ₂ Si0 ₄ Silicone rubber ― 624 2.26 0.19 No abnormality Comparative example 5 Mg ₂ Si0 ₄ silicone rubber one 3280 2.14 0.20 different None Comparative Example 6 Silicone rubber - 1130 1.70 0.16 No change

(*): In place of the coated MgO powder, using A1 ₂ 0 ₃ powder uncoated

As is evident from the above results, the coated magnesium oxide powder of the present invention that satisfies both the angle of repose and the tap density was subjected to a spheroidizing treatment (Table 1, Examples 1, 3 to 6) and fired. Both of those obtained by mixing the obtained powders (Table 1, Example 2) have excellent moisture resistance. The resin composition filled with these powders (Table 2, Examples 7 to 14) has excellent fluidity, and the molded body has high thermal conductivity and moisture resistance. It was confirmed that it was excellent.

On the other hand, the powder of Comparative Example 1 was excellent in the moisture resistance, but the tap density was lower than the range of the present invention. The fluidity was low when filled with epoxy resin (Table 2, Comparative Example 3) and when filled with silicone rubber (Table 2, Comparative Example 5).

Since the powder of Comparative Example 2 was not coated with the double oxide, the moisture resistance was very low as shown in Table 1.

In addition, the resin composition obtained by filling the conventional alumina powder in place of the magnesium oxide powder (Table 2, Comparative Examples 4 and 6) is excellent in fluidity and moisture resistance, but has poor thermal conductivity. Was inferior. Industrial applicability

As described in detail above, the coated magnesium oxide powder of the present invention has excellent moisture resistance, and when used as a filler, has excellent filling properties, can be highly filled into a resin, and can be used as a heat conductive filler. Useful.

The resin composition obtained by filling the coated magnesium oxide powder has excellent fluidity, and the molded body has high heat dissipation and moisture resistance. It is very useful as a component material of a substrate, an adhesive or an adhesive sheet, a resin circuit board, a metal base circuit board, a metal-clad laminate, a metal-clad laminate with an inner layer circuit, etc., and its industrial value is extremely high. high.

Claims

Scope of Claim 1. A coated magnesium oxide powder whose surface is coated with a double oxide, the repose angle is 55 degrees or less, and the tap density is 1.65 gZm1 or more.

2. The coated magnesium oxide powder according to claim 1, wherein the double oxide contains one or more elements selected from the group consisting of aluminum, iron, silicon and titanium, and magnesium.

3. The coated magnesium oxide powder according to claim 1 or 2, comprising 5 to 50 mass% of the double oxide.

4. an average particle size of ^{5 X 1 0- 6 ~ 500 X} 1 0- 6 m,: 6 £ Ding specific surface area of 5

1 0 ³ m is ² / kg or less, coated magnesium oxide powder according to any one of the range of 1 to 3 claims.

5. A resin composition comprising the coated magnesium oxide powder according to any one of claims 1 to 4.

6. The resin composition according to claim 5, wherein the resin of the resin composition is an epoxy resin.

7. The resin composition according to claim 5, wherein the resin of the resin composition is silicone rubber.

8. An electronic device using the resin composition according to any one of claims 5 to 7.