JP4197141B2 - Spherical alumina powder and use thereof - Google Patents

Description

The present invention relates to a spherical alumina powder and its use. Specifically, the present invention relates to a spherical alumina powder which has been surface-treated with an acrylic silane coupling agent, a mixed powder containing the same, and an epoxy resin composition filled with the powder.

When the epoxy resin is used as a semiconductor encapsulant, inorganic oxide powders such as spherical fused silica and spherical alumina are used as fillers because it is necessary to ensure insulation. Spherical alumina has the advantage of higher thermal conductivity than spherical fused silica.

  Spherical alumina is manufactured by putting raw material powder such as alumina and aluminum hydroxide into a high temperature flame and spheroidizing it. Unlike spherical fused silica, which is also manufactured by high temperature flame treatment, surface OH groups are reduced. Therefore, there is little aggregation of powder.

In view of one of the important characteristics of a semiconductor encapsulant having moisture resistance reliability, it has been proposed to subject a spherical alumina powder raw material to a surface treatment with a silane coupling agent having an alkoxy group (Patent Document 1). This improved the moisture resistance reliability, but the problem was that the strength and elastic modulus were not improved to the level of spherical fused silica.
Japanese Patent No. 2947072

  An object of the present invention is to provide a spherical alumina powder that can be highly filled and an epoxy resin composition filled therewith in order to improve the strength, elastic modulus, and moisture resistance reliability of an epoxy resin composition that is convenient as a semiconductor encapsulant. Is to provide. An object of the present invention is to surface-treat a spherical alumina powder raw material, preferably a spherical alumina powder raw material having two or more maximum peaks, with an acrylic silane coupling agent, and further, the spherical alumina powder and an acrylic This can be achieved by using in combination with fused spherical silica fine powder that has been surface-treated with a silane coupling agent.

That is, in the present invention, a spherical alumina powder raw material having an average particle size of 100 μm or less, an average sphericity of 0.80 or more, and a surface OH group number of 10 / nm ² or less is subjected to a surface treatment with an acrylic silane coupling agent. It is a spherical alumina powder characterized by being made. In this case, the acrylic silane coupling agent is represented by the chemical formula (1), and the particle size distribution of the spherical alumina powder raw material has two or more maximum peaks, and one of the maximum peaks is 3 μm. The following is preferable.

_{(C n H 3n O) 3} -Si-C m H 2m -0-COCH = CH 2 ··· formula (1)
In the formula, R is a methyl group or an ethyl group, and n is an integer of 1 or more. m is 0 or an integer of 1 or more.

Further, the present invention is characterized in that 20% by mass or less (not including 0) of the spherical alumina powder is mixed and replaced with a spherical fused silica fine powder subjected to a surface treatment with an acrylic silane coupling agent. It is a spherical alumina mixed powder. In this case, it is preferable that the average particle diameter of the spherical fused silica powder raw material subjected to the surface treatment with the acrylic silane coupling agent is 5 μm or less. Furthermore, the present invention is an epoxy resin composition comprising the spherical alumina powder or the spherical alumina mixed powder.

According to the present invention, a spherical alumina powder or a spherical alumina mixed powder that can be highly filled into an epoxy resin is provided. Therefore, the strength, elastic modulus, and moisture resistance reliability of the filled epoxy resin composition are melted. It is comparable to that filled with spherical silica powder and has high thermal conductivity.

The spherical alumina powder raw material used in the present invention has an average particle size of 100 μm or less, an average sphericity of 0.80 or more, and a surface OH group number of 10 / nm ² or less. When the average particle size exceeds 100 μm, the viscosity of the epoxy resin composition increases rapidly. In addition, when the average sphericity is less than 0.80 or the number of surface OH groups exceeds 10 / nm ² , the strength and elastic modulus of the epoxy resin composition are sufficiently obtained even when the surface treatment according to the present invention is performed. It cannot be improved.

The average sphericity can be measured using a scanning electron microscope (“JXA-8600M type” manufactured by JEOL Ltd.) and an image analysis device (manufactured by Nippon Avionics Co., Ltd.). That is, the projected area (A) and the perimeter (PM) of the particles are measured from the SEM photograph of the powder. When the area of a perfect circle corresponding to the perimeter (PM) is (B), the roundness of the particle is expressed as A / B. Therefore, assuming a perfect circle having the same circumference as that of the sample particle (PM), PM = 2πr and B = πr ² , so that B = π × (PM / 2π) ² . The roundness can be calculated as roundness = A / B = A × 4π / (PM) ² . Therefore, in the present invention, 100 arbitrary particles are measured, and the average value is used as the average sphericity.

In the present invention, the number of surface OH groups is an OH group that reacts with or possibly reacts with a silane coupling agent. This is because the moisture content X (ppm) generated at a temperature of 550 to 900 ° C. is measured by the Karl Fischer method, and the specific surface area of the powder is calculated from Ym ² / g, the formula: surface OH group number Z (pieces / nm ² ) = 0. .0668 × X / Y.

  The spherical alumina powder raw material used in the present invention is based on the existing thermal spraying technology (for example, “Technology for Thermal Spray Collection for Steelmaking Furnace Furnace”, Steel Research 1982 310), hydrogen, natural gas, acetylene gas, propane gas, It can be manufactured by putting raw material powder into a high-temperature flame formed of a fuel gas such as butane and an auxiliary combustion gas such as oxygen gas or air, and melt spheroidizing. As the raw material, alumina powder, aluminum hydroxide powder, aluminum sulfate powder or the like is used, and alumina powder with little change in particle size before and after spheroidization is preferable. Moreover, the method of burning a metal aluminum powder in a high temperature flame may be sufficient, and it becomes easy to obtain the fine spherical alumina powder with an average particle diameter of 10 micrometers or less by this.

  In the method for producing the spherical alumina powder raw material, the average particle diameter of the spherical alumina powder raw material is adjusted by adjusting the particle size of the raw material before spheroidization, the average sphericity, and the surface OH group number is adjusted by the amount of fuel gas during spheroidization. It can be adjusted by the supply amount of the raw material powder.

  The spherical alumina powder of the present invention is obtained by surface-treating the above spherical alumina powder raw material, preferably with an acrylic silane coupling agent represented by the above chemical formula (1). When the surface treatment is performed with an acrylic silane coupling agent on a spherical alumina powder raw material with an adjusted number of OH groups, the epoxy resin composition can be well dispersed and highly filled, and the strength and elastic modulus of the epoxy resin composition can be reduced. Greatly improved. Such an effect is not exhibited by a silane coupling agent having an alkoxy group or a silane coupling agent having an amino group. A particularly preferred acrylic silane coupling agent is 3-acryloxypropyltrimethoxysilane represented by chemical formula (2).

_{(CH 3 O) 3 -Si-} C 3 H 6 -0-COCH = CH 2 ··· formula (2)

It is preferable that the usage-amount of an acryl-type silane coupling agent is 0.2-5 mass parts with respect to 100 mass parts of spherical alumina powder raw materials. If the amount is less than 0.2 parts by mass, the effect is small, and even if the amount is more than 5 parts by mass, an effect commensurate with the amount used is not exhibited.

  As the surface treatment method, a spray method using a fluid nozzle, a stirring method having shearing force, a dry method such as a ball mill or a mixer, or a wet method such as an aqueous or organic solvent method can be employed. It is important that the stirring method be performed to such an extent that the spherical alumina powder raw material or the spherical alumina powder does not break. The system temperature in the dry method or the drying temperature after the treatment is appropriately determined in a region where thermal decomposition does not occur depending on the type of the surface treatment agent, but is generally 80 to 150 ° C.

  The spherical alumina powder of the present invention can be further reduced in viscosity when mixed with the epoxy resin by adjusting the particle size of the spherical alumina powder raw material. That is, it has two or more maximum peaks, and one of the maximum peaks is 3 μm or less. Such an effect of lowering viscosity is obtained by mixing and replacing 20% by mass (excluding 0) of the spherical alumina powder of the present invention with a spherical fused silica fine powder surface-treated with an acrylic silane coupling agent. Conduced by The average particle size of the spherical fused silica fine powder is preferably 5 μm or less as the average particle size of the spherical fused silica powder subjected to the surface treatment with the acrylic silane coupling agent.

  The spherical alumina powder or spherical alumina mixed powder of the present invention can be used as a filler for producing various resin compositions, and is particularly suitable for the production of epoxy resin compositions. The epoxy resin composition of this invention has a use as a semiconductor sealing agent.

  The epoxy resin used in the present invention has two or more epoxy groups in one molecule. For example, bisphenol A type epoxy resin, phenol A type epoxy resin, phenol novolac type epoxy resin, biphenyl type are exemplified. An epoxy resin, a dicyclopentadiene type epoxy resin, a naphthalene ring-containing epoxy resin, a brominated epoxy resin, and the like, and one or more of these are used. In particular, when it is desired to impart characteristics such as low moisture absorption, a biphenyl type epoxy resin is preferable. When the application of the epoxy resin composition is a liquid epoxy resin composition such as an underfill material, the room temperature of a bisphenol type epoxy resin such as a bisphenol A type epoxy resin or a bisphenol F type epoxy resin, or an alicyclic epoxy resin A liquid epoxy resin is used.

  The epoxy resin curing agent is not particularly limited as long as it is cured by reacting with the epoxy resin. For example, phenol, cresol, xylenol, resorcinol, chlorophenol, t-butylphenol, nonylphenol, isopropylphenol, octylphenol, etc. Bisphenol compounds such as novolak-type resin, polyparahydroxystyrene resin, bisphenol A and bisphenol S obtained by reacting a mixture of one or more selected from the group with formaldehyde, paraformaldehyde or paraxylene under an oxidation catalyst , Trifunctional phenols such as pyrogallol and phloroglucinol, acid anhydrides such as maleic anhydride, phthalic anhydride and pyromellitic anhydride, metaphenylenediamine, diaminodiphenylmethane Aromatic amines such as diaminodiphenyl sulfone, and the like.

  In the epoxy resin composition of the present invention, a curing accelerator can be blended in order to accelerate the reaction between the epoxy resin and the curing agent. Examples of the curing accelerator include 1,8-diazabicyclo (5,4,0) undecene-7, triphenylphosphine, benzyldimethylamine, 2-methylimidazole and the like.

Furthermore, the following component can be mix | blended with the epoxy resin composition of this invention as needed. That is, as a low stress agent, silicone rubber, polysulfide rubber, acrylic rubber, butadiene rubber, rubbery substances such as styrene block copolymers and saturated elastomers, various thermoplastic resins, resinous substances such as silicone resins, Is an epoxy resin, a resin obtained by modifying a part or all of a phenol resin with aminosilicone, epoxysilicone, alkoxysilicone, or the like. As a silane coupling agent, γ-glycidoxypropyltrimethoxysilane, β- (3,4- Epoxy cyclohexyl) Epoxy silanes such as ethyltrimethoxysilane, aminopropyltriethoxysilane, ureidopropyltriethoxysilane, aminosilanes such as N-phenylaminopropyltrimethoxysilane, phenyltrimethoxysilane, methyltri Hydrophobic silane compounds such as methoxysilane and octadecyltrimethoxysilane, mercaptosilane and the like, flame retardant aids such as Sb ₂ O ₃ , Sb ₂ O ₄ and Sb ₂ O ₅ , flame retardants such as halogenated epoxy resins and phosphorus Examples of colorants such as compounds include carbon black, iron oxide, dyes, and pigments.

  The epoxy resin composition of the present invention can be produced by stirring, dissolving, mixing, and dispersing predetermined amounts of each of the above materials. A device for mixing, stirring, and dispersing these mixtures is not particularly limited, and a lykai machine equipped with a stirring and heating device, a three-roll, a ball mill, a planetary mixer, and the like can be used. Moreover, you may use combining these apparatuses suitably.

Examples 1-5 Comparative Examples 1-6
Alumina powder was supplied into a high-temperature flame formed by LPG and oxygen gas, and spheroidizing treatment was performed. By adjusting the amount of LPG, spherical alumina powder raw materials AK having different average particle diameter, average sphericity, and surface OH group number were produced, and surface treatment was performed with silane coupling agents AD. In the surface treatment, 1 kg of spherical alumina powder raw material and the addition amount (outer percent%) shown in Table 1 of the silane coupling agent are put into a 10 liter container having a ball diameter of 20 mm and a ball filling rate of 50% by volume. Under normal pressure conditions, the operation was carried out at a rate of once per second for 1 hour and then dried at 120 ° C. for 1 hour. The silane coupling agent has a general formula, X ₃ —Si—C _n H _2n —O—Y (provided that functional groups X and Y and n number are described in Table 2).

  An epoxy resin composition was produced using the obtained spherical alumina powder, and (1) viscosity, (2) strength, (3) elastic modulus, and (4) moisture resistance reliability were measured as follows. In Comparative Example 6, fused spherical silica powder L (Comparative Example 6) was used instead of the spherical alumina powder. These results are shown in Table 5.

(1) Viscosity 45 parts by mass of the resin component prepared at the ratio shown in Table 3 and 55 parts by mass of spherical alumina powders A to K or fused spherical silica powder L are mixed to obtain an E type viscometer type (manufactured by Tokyo Keiki Co., Ltd.). Using an “EHD viscometer”), the viscosity at a temperature of 40 ° C. and a rotation speed of 5 rpm was measured.

(2) Strength, elastic modulus 40 parts by mass of the resin component prepared in the ratio of Table 4 and 60 parts by mass of the spherical alumina powders A to K or the fused spherical silica powder L are mixed, according to JIS K 6911, A 10 × 4 × 100 mm anti-folding rod was molded under the conditions of 175 ° C., 6.9 MPa, and molding time of 2 minutes, and the room temperature strength and elastic modulus were measured.

(3) Moisture resistance reliability 16-pin monitor IC with aluminum wiring is transfer molded, and after curing, immersed in a 260 ° C solder bath for 10 seconds, then 20V is applied in water vapor at 120 ° C and 2 atm to open the aluminum wiring. The time until the sum of the defect rate (disconnection rate) and the leak defect rate (the rate at which the leakage current value between the aluminum wires was 10 nA or more) reached 50% or more was determined. The number of samples is 20.

  As is clear from Tables 1 to 5, the epoxy resin composition using the spherical alumina powder of the present invention was superior to the comparative example in all of viscosity, strength, elastic modulus, and moisture resistance reliability.

Examples 6-9
In Examples 6 and 7, the spherical fused silica powder L was mixed with the spherical alumina powder raw material B. In Example 8, spherical alumina powder raw materials B and H were used, and a spherical alumina powder raw material having two maximum peaks, one of which was 3 μm or less was prepared. In Example 9, the spherical alumina mixed powder raw material in which the spherical fused silica powder L was further mixed in Example 8 was prepared. The test was conducted in the same manner as in Example 1 except that these raw materials were used in place of the spherical alumina powder raw material of Example 1. The results are shown in Table 7.

  From Tables 6 and 7, the viscosity is further reduced by using a spherical alumina powder raw material having two or more maximum peaks, one of which is 3 μm or less, and the spherical alumina powder and acrylic silane coupling agent of the present invention. It can be seen that the viscosity was further reduced by using in combination with the spherical fused silica powder surface-treated with.

According to the present invention, a spherical alumina powder or a spherical alumina mixed powder that can be highly filled into an epoxy resin is provided. Therefore, the strength, elastic modulus, and moisture resistance reliability of the filled epoxy resin composition are melted. It is comparable to that filled with spherical silica powder and has high thermal conductivity. The epoxy resin composition of the present invention is used as a semiconductor sealing agent.

Claims (4)

A spherical alumina powder raw material having an average particle size of 100 μm or less, an average sphericity of 0.80 or more, and a surface OH group number of 10 / nm ² or less is subjected to a surface treatment with an acrylic silane coupling agent. A spherical alumina powder. The acrylic silane coupling agent is represented by the chemical formula (1), and the particle size distribution of the spherical alumina powder raw material has two or more maximum peaks, and one of the maximum peaks is 3 μm or less. The spherical alumina powder according to claim 1.
_{(C n H 3n O) 3} -Si-C m H 2m -0-COCH = CH 2 ··· formula (1)
In the formula, R is a methyl group or an ethyl group, and n is an integer of 1 or more.
m is 0 or an integer of 1 or more. 3 or less (not including 0) of the spherical alumina powder is mixed and replaced with a spherical fused silica fine powder that has been surface-treated with an acrylic silane coupling agent. The spherical alumina mixed powder described. An epoxy resin composition comprising the spherical alumina powder according to claim 1 or 2, or the spherical alumina mixed powder according to claim 3.