JP2009215134A - Water resistant spherical particle, resin composition containing it, its producing method, filler being aggregation of the water resistant spherical particle and semiconductor resin sealing agent containing the filler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water resistant spherical particle which has precise and superior sphericity although the content of magnesium oxide with a high thermal conductivity is large, which can be highly filled in a sealing resin and, in addition, which has extremely superior water resistance, a resin composition containing it, its producing method, a filler being the aggregation of the water resistant spherical particle and a semiconductor resin sealing agent containing the filler. <P>SOLUTION: The water resistant spherical particle is characterized in that a layer being constituted of at least one phase selected from among Mg<SB>2</SB>SiO<SB>4</SB>, MgAl<SB>2</SB>O<SB>4</SB>, MgSiO<SB>3</SB>, Mg<SB>2</SB>Al<SB>4</SB>Si<SB>5</SB>O<SB>18</SB>, Mg<SB>3</SB>Al<SB>2</SB>Si<SB>3</SB>O<SB>12</SB>and Mg<SB>4</SB>Al<SB>10</SB>Si<SB>2</SB>O<SB>3</SB>is formed on the surface of the spherical particle containing magnesium oxide and that a ratio of a major side to a minor side of 1.0-1.15 in average. The producing method of the water resistant spherical particle is characterized in that the water resistant spherical particle is obtained by forming a layer being constituted of at least one phase selected from among Mg<SB>2</SB>SiO<SB>4</SB>, MgAl<SB>2</SB>O<SB>4</SB>, MgSiO<SB>3</SB>, Mg<SB>2</SB>Al<SB>4</SB>Si<SB>5</SB>O<SB>18</SB>, Mg<SB>3</SB>Al<SB>2</SB>Si<SB>3</SB>O<SB>12</SB>and Mg<SB>4</SB>Al<SB>10</SB>Si<SB>2</SB>O<SB>3</SB>is formed on the surface of the spherical particle by cooling and solidifying a molten particle containing magnesium oxide. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention provides Mg ₂ SiO ₄ , MgAl ₂ O ₄ , MgSiO ₃ , Mg ₂ Al ₄ Si ₅ O ₁₈ , Mg ₃ Al ₂ Si ₃ O ₁₂ and Mg ₄ Al ₁₀ Si on the surface of spherical particles containing magnesium oxide. Water-resistant spherical particles in which a layer composed of at least one phase selected from ₂ O ₃ is formed, a resin composition containing the same, a method for producing the same, and a filler that is an aggregate of the water-resistant spherical particles and Relates to a semiconductor resin encapsulant containing

  Conventionally, as a heat radiation filler such as a semiconductor resin encapsulant, spherical amorphous silica has been frequently used because of its good sphericity, easy high filling, and low cost. However, in recent years, with higher integration and higher power of semiconductor devices, the amount of heat generated from the semiconductor devices has increased, and in such applications, spherical heat-dissipating fillers with higher thermal conductivity have been demanded. Highly thermal conductive spherical alumina is often used.

  Although spherical alumina has a thermal conductivity that is an order of magnitude greater than that of spherical amorphous silica, it is inferior to spherical amorphous silica in terms of sphericity and compactness, and has the high thermal conductivity inherent to alumina. It is not fully demonstrated. Spherical alumina is generally manufactured through a spheroidizing process similar to spherical amorphous silica, but the solid structure shrinks because the amorphous structure of the melt is almost maintained during the solidification of spherical amorphous silica. Is extremely small and tends to be spherical, whereas in the case of spherical alumina, solidification shrinkage is large due to solidification from a low-density melt to high-density crystalline alumina, thereby avoiding the generation of defects. I can't. For this reason, spherical alumina is greatly inferior to spherical amorphous silica in shape and density as a sphere, and the filling property when used as a heat radiation filler is deteriorated. In addition, since alumina has a high hardness, it has a drawback that the mold for resin molding is significantly worn out.

  Magnesium oxide, on the other hand, has the highest thermal conductivity among practical oxide ceramics, has good insulating properties, and is relatively low in hardness. However, since magnesium oxide is difficult to form into a dense sphere by melting at a high melting point, it is difficult to produce a heat dissipating filler that can be filled more than alumina, and the surface area cannot be reduced. It is also difficult to avoid the disadvantage of poor water resistance. For the reasons described above, magnesium oxide has not been widely applied industrially as a heat dissipating filler for semiconductor resin sealants and the like.

From the above viewpoints, improvements have been made in the spheroidization and water resistance of magnesium oxide (see Patent Documents 1 and 2). In Patent Document 1, alumina particles and / or silica particles are added to a magnesium oxide powder and granulated using a spray dryer to obtain a spherical granule. It has been disclosed to produce a magnesium oxide based material by melting at least a portion of the granulate and then rapidly cooling it. On the other hand, Patent Document 2 discloses a spherical coated magnesium oxide powder that is coated with a double oxide and has an average shape factor of 1.25 or less, and a melting point of 2773 K or less on the surface of the magnesium oxide powder. It is disclosed that a coated magnesium oxide powder is produced by the presence of a compound of an element forming a double oxide and melting at a high temperature.
Japanese Patent No. 2590491 International Publication WO 2005/033215

  However, in the production method described in Patent Document 1, the alumina and silica particles and a part of the magnesium oxide powder in contact therewith are melted, that is, the magnesium oxide material is obtained using the alumina and silica particles as a flux. Therefore, it is unlikely that spherical magnesium oxide-based particles having a fine and good spherical shape can be obtained. Therefore, depending on the magnesium oxide-based material manufactured by the manufacturing method described in Patent Document 1, the substantial filling property to the sealing resin cannot be improved, and the thermal conductivity of the sealing agent is improved. Is considered difficult. In addition, in the production method described in Patent Document 1, when a substance other than magnesium oxide, which is presumed to be produced by melting and solidifying a part of the alumina and silica particles and the magnesium oxide powder in contact therewith, sufficiently covers the magnesium oxide. In some applications, there is a high possibility of problems in water resistance.

  In addition, in the production method described in Patent Document 2, the density inside the obtained spherical powder is improved by using a powder produced by electrofusion or sintering for magnesium oxide before spheroidization. It is possible, however, that the sphericity of the spherical coated magnesium oxide powder appears to depend greatly on the sphericity of the magnesium oxide powder before spheronization, so long as the powder is obtained through a grinding process, It seems difficult to increase the sphericity of the coated magnesium oxide powder. Also, in the spheronization process, it is assumed that there is a high possibility that defects are generated at the interface between the coating layer and / or the coating layer and the internal magnesium oxide due to shrinkage accompanying the solidification of the coating layer made of a double oxide. Depending on the water resistance, there is a high possibility of problems in water resistance.

  Therefore, the present invention contains a high amount of highly heat-conductive magnesium oxide, is dense and has a good sphericity, can be highly filled into a sealing resin, and in addition, has a water-resistant spherical shape with extremely good water resistance. It is an object of the present invention to provide particles, a resin composition containing the same, a method for producing the same, a filler that is an aggregate of the water-resistant spherical particles, and a semiconductor resin sealant containing the filler.

In order to achieve the above object, the present inventors have made extensive studies, and as a result, Mg ₂ SiO ₄ , MgAl ₂ O ₄ , MgSiO ₃ , Mg ₂ Al ₄ are formed on the surface of the spherical particles containing magnesium oxide. By forming a layer composed of at least one phase selected from Si ₅ O ₁₈ , Mg ₃ Al ₂ Si ₃ O ₁₂ and Mg ₄ Al ₁₀ Si ₂ O ₃ , it contains a large amount of magnesium oxide with high thermal conductivity. However, the present inventors have found that it is dense and has a good sphericity, can be highly filled into a sealing resin, and in addition, can have extremely good water resistance. That is, in the present invention, Mg ₂ SiO ₄ , MgAl ₂ O ₄ , MgSiO ₃ , Mg ₂ Al ₄ Si ₅ O ₁₈ , Mg ₃ Al ₂ Si ₃ O _12, and Mg ₄ are formed on the surface of spherical particles containing magnesium oxide. A layer composed of at least one phase selected from Al ₁₀ Si ₂ O ₃ is formed, and the ratio of the long side to the short side is 1.0 to 1.15 on average. Spherical particles. Further, the present invention is a resin composition containing water-resistant spherical particles, and the present invention further comprises cooling and solidifying molten particles containing magnesium oxide to form Mg ₂ SiO ₄ , MgAl on the surface layer of the spherical particles. Forming at least one phase selected from ₂ O ₄ , MgSiO ₃ , Mg ₂ Al ₄ Si ₅ O ₁₈ , Mg ₃ Al ₂ Si ₃ O ₁₂ and Mg ₄ Al ₁₀ Si ₂ O ₃ to form water-resistant spherical particles Is a method for producing water-resistant spherical particles.

  The water-resistant spherical particles according to the present invention exhibit high thermal conductivity, have both denseness and high sphericity, and are suitably used as insulating heat radiation fillers such as fillers for semiconductor resin sealants. That is, the present invention is an aggregate of the above water-resistant spherical particles, a filler characterized by having an average particle diameter of 5 to 500 μm, and a semiconductor resin encapsulant containing the filler and a resin.

  As described above, according to the present invention, while containing a large amount of highly heat-conductive magnesium oxide, it is dense and has good sphericity, and can be filled into a sealing resin, and in addition, has excellent water resistance. Water-resistant spherical particles, a resin composition containing the same, a method for producing the same, a filler that is an aggregate of the water-resistant spherical particles, and a semiconductor resin encapsulant containing the filler can be provided.

In the water-resistant spherical particles according to the present invention, is the spherical particle containing magnesium oxide (a) a spherical particle exhibiting a eutectic structure composed of a phase composed of magnesium oxide and a phase composed of MgAl ₂ O ₄ ? (B) Magnesium oxide and Mg ₂ SiO ₄ are preferably the main components.

When the spherical particles containing magnesium oxide are spherical particles exhibiting a eutectic structure composed of (a) a phase composed of magnesium oxide and a phase composed of MgAl ₂ O ₄ , the ratio of the long side to the short side is an average. 1.0 to 1.15, but preferably 1.0 to 1.1. This is because if the ratio of the long side to the short side of the spherical particles is within this range, the filling property and moldability into the sealing resin are particularly excellent. Spherical particles in such a range can be easily obtained by rapidly cooling by introducing spherical molten particles, which will be described later, into the refrigerant because rapid cooling with the refrigerant can suppress contact between particles before solidification. .

  In the water-resistant spherical particles according to the present invention, the eutectic structure is a reaction in which a single liquid phase (melt) separates at the eutectic temperature during cooling, and a plurality of different solid phases crystallize. It is a structure generated by a crystal reaction, and is a regular structure in the form of layers, fibers or rods, or the like.

  The crystalline spherical particles produced through the melt-solidification process generally have a grain texture, and the existence of a large number of grain boundaries lowers the substantial thermal conductivity, thus reducing the intrinsic thermal conductivity of the substance. It is difficult to obtain. On the other hand, the eutectic structure has high continuity of constituent phases, and an interface having good consistency between the constituent phases is formed, and the thermal conductivity inherent to the substance is easily exhibited.

  The eutectic temperature is generally lower than the melting point of each solid phase to be crystallized, and if a eutectic reaction is used, the phase can be crystallized by a process at a temperature lower than the melting point of the desired phase. For example, in general, magnesium oxide has a high melting point of 2824 ° C., so that it is difficult to melt by adding it to a chemical flame. However, according to a melt solidification reaction with a composition close to a eutectic reaction or a eutectic composition, It becomes possible to crystallize the magnesium oxide phase by adding it to the.

  Eutectic melts generally have a very low solidification temperature, low viscosity, good flowability, and low solidification shrinkage, so that solidification into crystalline materials of other compositions is possible even when solidifying into crystalline materials. It is easy to obtain spherical particles having a good spherical shape compared to. Further, a composition whose composition ratio does not greatly differ from the eutectic composition has the same characteristics as the eutectic composition melt and its solidification.

When the spherical particles containing magnesium oxide have (b) magnesium oxide and Mg ₂ SiO ₄ as main components, the ratio of the long side to the short side of the water-resistant spherical particles according to the present invention is 1.0 to on average. 1.1. In this case, the spherical particles containing magnesium oxide are obtained by cooling and solidifying molten particles containing Mg, Si and O as main components to obtain spherical particles having an amorphous phase as a main phase. It is preferable to crystallize spherical particles whose main phase is a phase by heating.

Since the spherical particles according to the present invention have the ratio of the long side to the short side of the spherical particles adjusted to a range of 1.0 to 1.1, the filling property to the sealing resin and the moldability are particularly excellent. Yes. Spherical particles in such a range can be easily obtained by passing through amorphous particles. That is, in the present invention, molten particles mainly composed of Mg, Si and O are cooled to obtain spherical particles composed of an amorphous phase mainly composed of Mg, Si and O. Spherical particles composed of this amorphous phase can be solidified in a non-equilibrium state, particularly by maintaining the atomic structure at the time of melting substantially by rapidly solidifying the molten particles with a liquid refrigerant. Therefore, it is easy to obtain spherical particles with extremely small solidification shrinkage and good spherical shape. Here, “amorphous” means an atomic structure of a phase in which a crystal lattice image cannot be confirmed by observation with a transmission electron microscope, but is an amorphous that is a main constituent phase of a spherical particle before crystallization. Even if a small amount of crystalline phase is contained in the phase, there is no problem because the characteristics such as the sphericity of the spherical particles after crystallization are not deteriorated. The obtained spherical particles composed of the amorphous phase are crystallized into magnesium oxide and Mg ₂ SiO ₄ by being heated to a predetermined temperature. At this time, since the spherical particles shrink isotropically, the good spherical shape of the amorphous particles is maintained, and crystalline spherical particles mainly composed of magnesium oxide and Mg ₂ SiO ₄ are obtained. Can do.

In the water-resistant spherical particles according to the present invention, magnesium oxide and Mg ₂ SiO ₄ are the main components if they contain trace amounts of components other than magnesium oxide and Mg ₂ SiO ₄ within a range that does not hinder non-crystallization or crystallization. For example, it means that A, P and O are 95% by weight or more. In addition, when Mg, Si and O are the main components, it is possible to contain a small amount of other components other than Mg, Si and O as long as they do not prevent non-crystallization or crystallization of Mg, Si and O. This means that, for example, Mg, Si and O are 95% by weight or more. Furthermore, Mg, Al, and O as the main component means that other components other than Mg, Al, and O may be included in a trace amount within a range that does not hinder the eutectic composition of Mg, Al, and O. For example, it means that Mg, Al and O are 95% by weight or more. In addition, the amorphous phase as the main phase means that the crystalline phase may be contained in a trace amount, for example, it means that the amorphous phase is 95% by weight or more. The case where it consists only of a phase and the case where a crystalline phase is contained between an amorphous phase are included. Further, the long side refers to the longest diameter of the spherical particles, and the short side refers to the shortest diameter of the spherical particles. The ratio of the long side to the short side can be measured using, for example, a laser microscope. In the water-resistant spherical particles according to the present invention, 50 spherical particles are measured using a laser microscope, and the average value is calculated.

  The spherical particles containing magnesium oxide preferably have an average particle size of 5 to 500 μm, more preferably 5 to 200 μm. If the average particle size of the spherical particles is less than 5 μm, the surface area becomes large, which may cause a problem in water resistance. If the average particle size of the spherical particles is larger than 500 μm, the filling property to the semiconductor sealing resin or the like is increased. Because it gets worse. Adjustment of the average particle diameter can be performed by classification with a sieve.

(A) In the case of spherical particles exhibiting a eutectic structure composed of a phase composed of magnesium oxide and a phase composed of MgAl ₂ O _{4, in} order to obtain spherical particles containing magnesium oxide, first, Mg, Al and A step of solidifying into a spherical shape by cooling the molten particles containing O as a main component is required. In addition, in order to obtain spherical particles containing magnesium oxide when (b) magnesium oxide and Mg ₂ SiO ₄ are the main components and the ratio of the long side to the short side is 1.0 to 1.1 on average. First, a step of solidifying into a spherical shape by cooling the molten particles mainly composed of Mg, Si and O is required. The molten particles are those in which the constituent components are spheroidized in a molten state. Such molten particles can be obtained, for example, by a flame method, an atomizing method, and a spin disk method, and particularly preferably by a flame method. The flame method is a method in which particles each consisting of a constituent component are passed through a high temperature region having a temperature equal to or higher than the melting point. For example, the prepared particles are put into a chemical flame or thermal plasma to be melted and melted. It is the method of obtaining the spherical particle. The atomization method is a method in which a raw material composed of constituent components is melted in a crucible or the like, and a melt is ejected from a discharge port opened in the crucible. The spin disk method is a method in which a melt is applied to a disk that rotates at high speed. It is the method of making it collide in the state which maintained the molten state.

  In the flame method, particles prepared by granulating powdery raw materials with a spray dryer, etc., and bulk materials obtained by sintering or melting and solidifying the raw materials are pulverized to use particles adjusted so as to obtain a desired particle size distribution. It is performed by putting the particles into a chemical flame or thermal plasma while suppressing the aggregation and melting them in the chemical flame or thermal plasma.

  In the flame method, a liquid precursor containing an element having a desired composition ratio such as a raw material colloidal liquid or an organometallic polymer can be used. It is carried out by spraying into plasma and evaporating the solvent or dispersion medium in a chemical flame or thermal plasma and then melting it. It is also possible to provide a low-temperature heating zone between the nozzle and the chemical flame or thermal plasma and evaporate the solvent or dispersion medium in the liquid raw material, and then put it into the chemical flame or thermal plasma.

  In the flame method, it is only necessary to obtain a high temperature of 2400 ° C. or higher as a generation source of the chemical flame. Used. In addition, oxygen, nitrogen, argon, carbon dioxide gas and mixed gas thereof, and water are used as a source of thermal plasma. When gas is used, an inductively coupled plasma apparatus is used, but water is used. It is preferred that

  In the case of the atomizing method or the spin disk method, the raw material may be any of powder, a molded body, a sintered body, and a solidified body, or a combination of two or more of these. These raw materials are accommodated in a crucible having a melting point higher than the melting point thereof, for example, a crucible made of Mo, W, Ta, Ir, Pt or the like, or a Cu crucible cooled by water or the like and then melted. The melting method may be any method as long as the raw material can be heated to a temperature equal to or higher than its melting point, and for example, high frequency, plasma, laser, electron beam, light, or infrared can be used. The raw material is preferably melted in an atmosphere in which the raw material is not evaporated or decomposed and the crucible is not significantly consumed. An optimum atmosphere is selected depending on the raw material and the material of the crucible used, such as in the air, in an inert gas, or in a vacuum.

  In the atomization method, spherical molten particles can be formed by ejecting a melt from pores opened in a crucible bottom or the like using gas pressure or the like. The spin disk method tilts the crucible, and in the same way as in the atomizing method, the melt collides with the rotating disk by, for example, jetting the melt from the pores opened at the bottom of the crucible using gas pressure etc. And spherical molten particles can be formed.

When the spherical particles containing magnesium oxide are spherical particles exhibiting a eutectic structure composed of (a) a phase composed of magnesium oxide and a phase composed of MgAl ₂ O ₄ , the proportion of the constituent components of the raw material before melting is adjusted There is a need to. It is necessary to collect the proportions of the constituent components of the raw material so that the molten particles immediately before solidification have an eutectic composition, but in order to obtain spherical particles with a good spherical shape and thermal conductivity, it is not always necessary to specify a eutectic point. It is not necessary to have the composition. For example, the weight ratio of magnesium oxide to aluminum oxide when the raw material is melted needs to be adjusted to be 43:57 to 57:43. By setting the composition ratio of such raw materials, a uniform eutectic structure is easily formed, and spherical particles having a good spherical shape can be obtained. As the raw material before melting, magnesium oxide and aluminum oxide are generally used. However, any material can be used as long as it becomes an oxide when melted, and hydroxide, carbonate, or the like may be used. The cooling step can be performed, for example, by putting spherical molten particles into a refrigerant and quenching. If it is the ratio of the component of the raw material in the manufacturing method of the spherical particle which concerns on this invention mentioned above, the spherical particle which exhibits a eutectic structure by cooling with the refrigerant | coolant about a spherical molten particle can be obtained.

Further, when the spherical particles containing magnesium oxide are mainly composed of (b) magnesium oxide and Mg ₂ SiO ₄ and the ratio of the long side to the short side is 1.0 to 1.1 on average, Mg, Si The molten particles containing O and O as main components can be obtained from, for example, magnesium oxide and silicon dioxide. In this case, the ratio of magnesium oxide and silicon dioxide as constituents of the molten particles is 65:35 in molar ratio from the former. It is preferable to be in the range of ˜85: 15. This is because when the proportion of silicon dioxide is larger than this range, spherical particles having high thermal conductivity cannot be obtained, and when the proportion of magnesium oxide is larger than this range, it becomes difficult to obtain spherical particles having a good spherical shape. In this case, the spherical molten particles are cooled to obtain spherical particles having an amorphous phase as a main phase. In this cooling step, the spherical molten particles are charged into the refrigerant while maintaining the molten state. The water-resistant spherical particles according to the present invention can be obtained by rapid cooling. In the case of molten particles mainly composed of Mg, Si and O, solidification in a non-equilibrium state is possible by rapid cooling with a liquid refrigerant, and the spherical particles are solidified in a state in which the atomic structure at the time of melting is substantially maintained. For this reason, it is easy to obtain spherical particles with extremely small solidification shrinkage and good spherical shape.

When spherical particles containing magnesium oxide are (a) spherical particles exhibiting a eutectic structure composed of a phase composed of magnesium oxide and a phase composed of MgAl ₂ O ₄ , and (b) magnesium oxide and Mg ₂ SiO ₄ In any case, the ratio of the long side to the short side is 1.0 to 1.1 on average, and as the refrigerant, a non-flammable liquid is preferable, and Al, Si using water as a dispersion medium, and A colloidal liquid containing at least one element selected from Mg can be suitably used. The concentration of the colloidal liquid is preferably in the range of 0.05 to 10% by weight. When the concentration is lower than this range, it is not possible to form a surface layer sufficient to impart water resistance to the spherical particles, and when the concentration is higher than this range, the sphericity of the spherical particles may be deteriorated. Because there is. By rapidly cooling the molten particles with such a refrigerant, the surface layer has Mg ₂ SiO ₄ , MgAl ₂ O ₄ , MgSiO ₃ , Mg ₂ Al ₄ Si ₅ O ₁₈ , Mg ₃ Al ₂ Si ₃ O ₁₂ and Mg ₄ Al _10. It is composed of one or more phases of Si ₂ O ₃ . In addition, by using quenching with a refrigerant, it is possible to suppress contact between particles before solidification and to form a good spherical shape.

  You may adjust the ratio of the long side of a molten particle which uses the obtained amorphous phase as a main phase to a short side to 1.0-1.1 on an average. The amorphous spherical particles are solidified in a state in which the atomic structure at the time of melting is substantially maintained by ultra-rapid cooling with a liquid refrigerant, and spherical particles having a very small solidification shrinkage and a good spherical shape can be obtained.

When the spherical particles containing magnesium oxide are mainly composed of (b) magnesium oxide and Mg ₂ SiO ₄ , and the ratio of the long side to the short side is 1.0 to 1.1 on average, it is further amorphous. Crystallization is performed by heating spherical particles whose main phase is the phase. The heating temperature at this time is preferably 1350 ° C. to 2100 ° C., more preferably 1450 ° C. to 1800 ° C. By heating in this way, the amorphous spherical particles can be crystallized to obtain spherical particles composed of magnesium oxide and Mg ₂ SiO ₄ . The obtained spherical particles composed of the amorphous phase are heated to a predetermined temperature to crystallize into magnesium oxide and Mg ₂ SiO ₄ . At this time, since the spherical particles shrink isotropically, crystalline spherical particles composed of magnesium oxide and Mg ₂ SiO ₄ are obtained, in which the good spherical shape of the amorphous particles is maintained. Can do. The desired spherical particles can be obtained by appropriately selecting the temperature, time, heating rate, etc. during heating. This heat treatment may be any method as long as spherical particles whose main phase is an amorphous phase can be heated at 1350 ° C. to 2100 ° C., such as resistance heating, high frequency induction heating using a susceptor, laser Any method such as heating, electron beam heating, light heating, or infrared heating may be used.

  Generally, a method of heating the entire crucible by storing amorphous spherical particles in a crucible made of ceramics such as aluminum oxide and magnesium oxide, or a high melting point metal such as molybdenum, tantalum, platinum, iridium, etc. A method of heating amorphous spherical particles while moving them in a tubular furnace made of the same material as the crucible provided with a predetermined temperature gradient and a soaking area, or amorphous spherical particles at a predetermined temperature. A method of heating while dropping in a vertical tubular furnace made of the same material as that of the crucible provided with a gradient and a soaking area is adopted.

  The heat treatment of the amorphous spherical particles may be performed in any atmosphere, such as in the air, in an inert gas, in a reducing gas, in a hydrocarbon gas, or in a vacuum, but is limited by the crucible used and the heating method. There is a case to receive.

  Since the water-resistant spherical particles according to the present invention have a good spherical shape, the fluid-resistant spherical particles have extremely good fluidity and exhibit extremely good moldability when filled into a resin. The obtained water-resistant spherical particles are classified so as to obtain a desired filling rate, and then subjected to a surface treatment as necessary to further improve the filling rate. As the surface treatment agent, a silane coupling agent is generally used, but titanate and aluminate coupling agents can also be used.

  The resin composition according to the present invention is preferably filled with the above-mentioned water-resistant spherical particles in a resin raw material such as an epoxy resin, a silicone resin, and a polyimide resin, or may be filled with silicone rubber or the like. Moreover, the resin composition which concerns on this invention is added with a hardening | curing agent, a hardening accelerator, etc. as needed at the time of shaping | molding.

  The filler according to the present invention is an aggregate of water-resistant spherical particles according to the present invention, and the average particle size thereof is preferably in the range of 5 to 500 μm. If it is less than this range, the surface area of the particles may be increased, which may cause a problem in water resistance. If it exceeds this range, the filling property to the semiconductor sealing resin or the like will be deteriorated. Adjustment of the average particle diameter can be easily performed by dry or wet classification using a sieve, and a filler having a desired particle size distribution can be obtained by selecting a sieve having an appropriate mesh size according to the application. it can.

  The semiconductor resin sealant according to the present invention is composed of the resin composition composed of the filler and the resin according to the present invention. A semiconductor resin sealant is a resin composition that protects integrated circuits from external heat, dust, moisture, impact, etc. In addition to a certain level of electrical insulation and water resistance, it has excellent moldability and heat dissipation ( High thermal conductivity) is required. The filler according to the present invention is an aggregate of spherical particles having a spherical shape and good thermal conductivity, has good fluidity and good moldability, and can increase the filling rate. A semiconductor resin encapsulant composed of a filler and a resin has excellent thermal conductivity, and is particularly suitable for a high performance integrated circuit having a large calorific value.

  When the resin is a solid material, the semiconductor resin encapsulant according to the present invention is molded by a compression molding method, a transfer molding method, or the like. In the compression molding method, the resin is melted and compressed in the cavity of the mold and cured so as to mold the filler, and all of the IC chip, die pad, bonding wire, and leads on the substrate previously set in the cavity. This is a method of sealing part of the frame. In the transfer molding method, the resin is melted in a pot outside the mold cavity, the molten resin and filler are sent into the cavity through a small hole, and the filler is molded in the cavity. This is a method of sealing each component in the same manner as the compression molding method.

  In addition, when the resin is a liquid encapsulant, the semiconductor resin encapsulant according to the present invention is necessary after mixing the liquid resin and filler, injecting into a required location with a dispenser or the like, or applying it. Accordingly, the solvent can be removed, and then the filler can be cured to form and sealed.

  In any method, the filler content is preferably about 60 to 90% by weight. When the filler content is less than this range, it is difficult to obtain a good thermal conductivity effect of the filler, and when it is more than this range, molding becomes difficult. The resin is selected from various types according to the purpose, the curing agent and curing accelerator are selected accordingly, and the optimum molding temperature is selected accordingly.

Example 1
Next, Example 1 of the water-resistant spherical particles according to the present invention will be described. As raw materials for the water-resistant spherical particles according to Example 1, MgO powder (MGO12PB manufactured by High Purity Chemical Laboratory Co., Ltd.) and α-Al ₂ O ₃ (AKP-30 manufactured by Sumitomo Chemical Co., Ltd.) powder were used. MgO powder and α-Al ₂ O ₃ powder are mixed by a wet ball mill using water at a weight ratio of 55:45, and the resulting slurry is granulated and dried to have an average particle size of 25 μm. Granular particles were obtained.

The obtained granular particles are supplied into a flame formed by the combustion of a mixed gas of oxygen and acetylene in parallel with the jet direction of the mixed gas, melted and spheroidized in the flame, and then the flame tip is in a fluid state Then, the molten particles were injected into flowing water to be solidified by being incident on a colloidal solution containing Al ₂ O ₃ having a concentration of 2% by weight.

The obtained spherical particles had an average particle size of 17 μm, and the ratio of the long side to the short side was 1.13 on average. The spherical particles are formed by X-ray diffraction using Cu-Kα rays and scanning electron microscope observation of the cross-section of the spherical particles, the surface layer is composed of MgAl ₂ O ₄ , and the portion other than the surface layer is composed of magnesium oxide, and MgAl ₂ It was found that a eutectic structure composed of a phase composed of O ₄ was exhibited.

  When the obtained spherical particles are treated with an epoxy silane coupling agent and the spherical particles are taken as 100%, 20% by weight of a novolac epoxy resin, 10% by weight of novolak phenol, 0.0. 4 wt% curing accelerator and 0.4 wt% carnauba wax were added and kneaded at 100 ° C. and pulverized. The obtained powder was press-molded at 170 ° C. and a pressure of 7 MPa to obtain a molded product having a diameter of 20 mm and a thickness of 3 mm. When the thermal conductivity of the obtained molding was measured by a laser flash method, a value of 3.31 W / mK was obtained. Further, when the molded product was kept in 2 atm water vapor at 120 ° C. for 200 hours to measure the moisture absorption rate, the water absorption rate was 0.3%, and no change was observed in the appearance of the molded product.

Example 2
Next, Example 2 of the water resistant spherical particles according to the present invention will be described. Similar to Example 1, except that MgO powder and α-Al ₂ O ₃ powder were used, and the weight ratio of MgO powder and α-Al ₂ O ₃ powder was changed to a ratio of 45:55. Granulation and drying were performed by a method to obtain granular particles having an average particle size of 24 μm, melt spheroidized by the same method as in Example 1, and then solidified to obtain spherical particles. The obtained spherical particles had an average particle diameter of 16 μm, and the ratio of the long side to the short side was 1.10 on average. The spherical particles are formed by X-ray diffraction using Cu-Kα rays and scanning electron microscope observation of the cross-section of the spherical particles, the surface layer is composed of MgAl ₂ O ₄ , and the portion other than the surface layer is composed of magnesium oxide, and MgAl ₂ It was found that a eutectic structure composed of a phase composed of O ₄ was exhibited.

  When the obtained spherical particles are treated with an epoxy silane coupling agent and the spherical particles are taken as 100%, 20% by weight of a novolac epoxy resin, 10% by weight of novolak phenol, 0.0. 4 wt% curing accelerator and 0.4 wt% carnauba wax were added and kneaded at 100 ° C. and pulverized. The obtained powder was press-molded at 170 ° C. and a pressure of 7 MPa to obtain a molded product having a diameter of 20 mm and a thickness of 3 mm. When the thermal conductivity of the obtained molding was measured by a laser flash method, a value of 3.04 W / mK was obtained. Further, when the molded product was kept in 2 atm water vapor at 120 ° C. for 200 hours to measure the moisture absorption rate, the water absorption rate was 0.3%, and no change was observed in the appearance of the molded product.

Example 3
Next, Example 3 of the water resistant spherical particles according to the present invention will be described. As raw materials for the water-resistant spherical particles according to Example 2, MgO powder (MGO12PB manufactured by High Purity Chemical Laboratory) and SiO ₂ powder (SIO07PB manufactured by High Purity Chemical Laboratory) were used. MgO powder and SiO ₂ powder are mixed by a wet ball mill using water at a molar ratio of 80:20 from the former, and the resulting slurry is granulated and dried using a spray dryer to form granules having an average particle size of 25 μm. Obtained particles.

The obtained granular particles are supplied into a flame formed by the combustion of a mixed gas of oxygen and acetylene in parallel with the jet direction of the mixed gas, melted and spheroidized in the flame, and then the flame tip is in a fluid state Injected into a colloidal solution containing ₂ % by weight of SiO ₂ at the concentration of molten particles, the molten particles were put into running water and solidified.

The obtained spherical particles had an average particle size of 22 μm, and the ratio of the long side to the short side was 1.04 on average. The spherical particles X-ray diffraction using Cu-K [alpha line, the analysis of transmission electron microscopy and installed in a transmission electron microscope characteristic X-ray by a semiconductor X-ray detector, a surface layer of about 0.1 [mu] m Mg ₂ SiO ₄ , it was found that the portion other than the surface layer was composed of an amorphous phase composed of Mg, Si and O.

The obtained spherical particles were placed in a MgO crucible and heat-treated at 1550 ° C. in air. The obtained spherical particles had an average particle diameter of 18 μm, and the ratio of the long side to the short side was 1.07 on average. The spherical particles are composed of Mg ₂ SiO _{4 on the} surface layer by X-ray diffraction using Cu—Kα rays and scanning electron microscope observation of the cut surface of the spherical particles, and the portions other than the surface layer are composed of MgO and Mg ₂ SiO _4. I found out.

  When the obtained spherical particles are treated with an epoxy silane coupling agent and the spherical particles are taken as 100%, 20% by weight of a novolac epoxy resin, 10% by weight of novolak phenol, 0.0. 4 wt% curing accelerator and 0.4 wt% carnauba wax were added and kneaded at 100 ° C. and pulverized. The obtained powder was press-molded at 170 ° C. and a pressure of 7 MPa to obtain a molded product having a diameter of 20 mm and a thickness of 3 mm. When the thermal conductivity of the obtained molding was measured by a laser flash method, a value of 3.15 W / mK was obtained. Further, when the molded product was kept in 2 atm water vapor at 120 ° C. for 200 hours to measure the moisture absorption rate, the water absorption rate was 0.3%, and no change was observed in the appearance of the molded product.

Example 4
Next, Example 4 of the water resistant spherical particles according to the present invention will be described. Using the same raw materials as in Example 3, granular particles having an average particle diameter of 25 μm were obtained by the same method as in Example 3.

  The obtained granular particles are supplied into a flame formed by the combustion of a mixed gas of oxygen and acetylene in parallel with the jet direction of the mixed gas, melted and spheroidized in the flame, and then the flame tip is in a fluid state Injected into a colloidal solution containing 2% by weight of MgO at a concentration of molten particles, the molten particles were poured into running water and solidified.

The obtained spherical particles had an average particle size of 22 μm, and the ratio of the long side to the short side was 1.04 on average. This spherical particle was found to be Mg ₂ SiO having a surface layer of about 0.2 μm by X-ray diffraction using Cu-Kα rays, observation with a transmission electron microscope, and analysis of characteristic X-rays using a semiconductor X-ray detector installed in the transmission electron microscope. ₄ , it was found that the portion other than the surface layer was composed of an amorphous phase composed of Mg, Si and O.

The obtained spherical particles were placed in a MgO crucible and heat-treated at 1550 ° C. in air. The obtained spherical particles had an average particle diameter of 18 μm, and the ratio of the long side to the short side was 1.07 on average. The spherical particles are composed of Mg ₂ SiO _{4 on the} surface layer by X-ray diffraction using Cu—Kα rays and scanning electron microscope observation of the cut surface of the spherical particles, and the portions other than the surface layer are composed of MgO and Mg ₂ SiO _4. I found out.

  When the obtained spherical particles are treated with an epoxy silane coupling agent and the spherical particles are taken as 100%, 20% by weight of a novolac epoxy resin, 10% by weight of novolak phenol, 0.0. 4 wt% curing accelerator and 0.4 wt% carnauba wax were added and kneaded at 100 ° C. and pulverized. The obtained powder was press-molded at 170 ° C. and a pressure of 7 MPa to obtain a molded product having a diameter of 20 mm and a thickness of 3 mm. When the thermal conductivity of the obtained molding was measured by a laser flash method, a value of 3.15 W / mK was obtained. Further, when the molded product was held in 2 atm water vapor at 120 ° C. for 200 hours to measure the moisture absorption rate, the water absorption rate was 0.5%, and no change was observed in the appearance of the molded product.

Comparative Example Next, a comparative example of spherical particles according to the present invention will be described. As a raw material for the spherical particles according to the comparative example, electrofused magnesia whose particle size was adjusted by classification so as to have a particle size distribution similar to that of Example 1 was molded in the same manner as in Example 1. When the thermal conductivity of the molded product was measured by the laser flash method, a value of 3.01 W / mK was obtained. Further, the moisture absorption rate was measured by holding the molded product in 2 atm water vapor at 120 ° C. for 200 hours. The water absorption rate was 3.1%, and a plurality of cracks occurred on the surface of the molded product. .

Claims (11)

Mg ₂ SiO ₄ , MgAl ₂ O ₄ , MgSiO ₃ , Mg ₂ Al ₄ Si ₅ O ₁₈ , Mg ₃ Al ₂ Si ₃ O ₁₂ and Mg ₄ Al ₁₀ Si ₂ O ₃ are formed on the surface of the spherical particles containing magnesium oxide. A water-resistant spherical particle, wherein a layer composed of at least one phase selected from the above is formed, and the ratio of the long side to the short side is 1.0 to 1.15 on average. The water-resistant spherical particles according to claim 1, wherein the spherical particles containing magnesium oxide are spherical particles exhibiting a eutectic structure composed of a phase composed of magnesium oxide and a phase composed of MgAl ₂ O _4. . The ratio of long side to short side is 1.0 to 1.1 on average, and the spherical particles containing magnesium oxide are mainly composed of magnesium oxide and Mg ₂ SiO _4. Water-resistant spherical particles as described.   The spherical particles containing magnesium oxide are obtained by cooling and solidifying molten particles containing Mg, Si and O as main components to obtain spherical particles having an amorphous phase as a main phase. 4. The water-resistant spherical particles according to claim 3, wherein the spherical particles used as a phase are crystallized by heating.   A resin composition comprising the water-resistant spherical particles according to claim 1. By cooling and solidifying molten particles containing magnesium oxide, Mg ₂ SiO ₄ , MgAl ₂ O ₄ , MgSiO ₃ , Mg ₂ Al ₄ Si ₅ O ₁₈ , and Mg ₃ Al ₂ Si ₃ O ₁₂ are formed on the surface layer of the spherical particles. And at least one phase selected from Mg ₄ Al ₁₀ Si ₂ O ₃ to form the water-resistant spherical particles according to claim 1.   The cooling and solidification is performed by introducing the molten particles into a refrigerant composed of a colloidal liquid containing one or more elements of Al, Si, and Mg using water as a dispersion medium. Item 8. A method for producing water-resistant spherical particles according to Item 7.   The molten particles are mainly composed of Mg, Al and O, and the weight ratio of magnesium oxide to aluminum oxide when the raw materials are melted is adjusted to be 43:57 to 57:43. The method for producing water-resistant spherical particles according to claim 6 or 7. The molten particles are mainly composed of Mg, Si and O,
A spherical particle having an amorphous phase as a main phase is obtained by cooling and solidifying the molten particles, and the spherical particles having the amorphous phase as a main phase are crystallized by heating. 8. A method for producing water-resistant spherical particles according to 6 or 7.   A filler characterized by being an aggregate of water-resistant spherical particles according to any one of claims 1 to 4, having an average particle size of 5 to 500 µm.   The semiconductor resin sealing agent containing the filler and resin of Claim 10.