Title of Invention	A THERMOSETTING RESIN COMPOSITION SUITABLE FOR PRODUCING MOULDED ARTICLES
Abstract	This invention relates to a thennosetting resin composition suitable for producing moulded articles suitable for electric and electronic appliances, comprising (a) a thennosetting resin and (b) magnesium hydroxide particles, the magnesium hydroxide particles satisfying the following requirements (i) to (iv), (i) the average secondary particle diameter, measured by a laser diffraction scattering method, is 0.5 to 5 J.lm, .(ii) the BET specific surface area is 0.1 to 10 m<sup>2</sup>/g, (iii) the total content of Fe and Mn as metal is 0.02 % by weight or less, and (iv) the total content ofU and Th as metal is 10 ppb or less.

Title of Invention

A THERMOSETTING RESIN COMPOSITION SUITABLE FOR PRODUCING MOULDED ARTICLES

Abstract

This invention relates to a thennosetting resin composition suitable for producing moulded articles suitable for electric and electronic appliances, comprising (a) a thennosetting resin and (b) magnesium hydroxide particles, the magnesium hydroxide particles satisfying the following requirements (i) to (iv), (i) the average secondary particle diameter, measured by a laser diffraction scattering method, is 0.5 to 5 J.lm, .(ii) the BET specific surface area is 0.1 to 10 m<sup>2</sup>/g, (iii) the total content of Fe and Mn as metal is 0.02 % by weight or less, and (iv) the total content ofU and Th as metal is 10 ppb or less.

Full Text	The present invention relates to a thermosetting resin composition suitable for producing moulded articles suitable for electric and electronic appliances. Field of the Invention The present invention relates to a thermosetting resin composition excellent particularly in flame retardancy, heat resistance and water resistance for electric and electronic devices. Further, the present invention also relates to molded articles formed by curing such a resin composition, particularly to sealing, coating or insulation of a part, a laminated board and a metal-clad laminated board for electric and electronic devices, such as a sealed molded article, a prepreg, a multi-layered circuit substrate and a laminated board for a circuit substrate. A semiconductor device and an integrated circuit device are sealed with various sealing materials for preventing influences caused by external vibrations, impact, dust, water and ambient gas. While a metal material, ceramic, glass, etc., have been used as sealing materials, a thermosetting resin is recently used for the sealing in most cases from the viewpoint of a cost and mass-productivity. With technological innovation in the field of semiconductors, the integration degree has increased, devices have decreased in size and wirings have come be finer and finer. Packages tend to decrease in size and thickness as well, and sealing materials are accordingly required to have high reliability. Further, the sealing materials are required to have strength and thermal conductivity, and it is general practice to use resins containing inorganic fillers. -2- Thermosetting resins typified by an epoxy resin are excellent in mechanical strength, electrical properties, thermal properties, adhesion, chemical durability and water resistance, so that they are applied to various 5 laminated boards formed in combination with glass, cloth, paper or synthetic fibers, such as a laminated board for a structure, a laminated board for heavy electric machines and equipment, a printed wiring board and a laminated metal board for a printed wiring board. 10 These electric and electronic parts are decreasing in size and thickness and have come to have high performances due to technological innovation. Therefore, it is required to decrease the size and thickness of semiconductor devices constituting the electric and 15 electronic parts and multi-layered printed wiring boards on which such parts are to be mounted, and they are required to attain high performances and to have high reliability. For the above reason, the mounting method of a 20 multi-layered printed wiring board is shifting from a pin-insertion type package to a surface-mounting type package and further to a bare chip mounting method in which a chip is directly mounted, so that a high adhesion of a resin is required. The high adhesion of a 25 resin can be attained by decreasing water absorption of the resin. A laminated board for a circuit board is processed under high-temperature and high-humidity conditions during the fabrication of the laminated board and mounting of electronic parts and then subjected to 30 the step of soldering by dipping it in a soldering bath, so that the laminated board is liable to undergo swelling or peeling. Therefore, the resin is required to have high heat resistance, high flame retardancy and long-term stability. 3 The above thermosetting resin used for sealing semiconductor devices or in the printed wiring board or laminated board (to be generally sometimes referred to as "electronic part" hereinafter) is required to have 5 high flame retardancy, and for this purpose, it is general practice to employ a method in which a bromine-containing epoxy resin and antimony oxide are incorporated into the resin. However, this method causes a problem that hydrogen bromide, bromine-containing gas, 10 antimony bromide, etc., are generated during combustion to do harm to human bodies and corrode a machine and equipment, and also causes an environmental safety problem on disposal of industrial wastes resulting from the process of producing electronic parts and disposal 15 of an epoxy resin molding material and electronic parts produced from such a molding material. Further, when an electronic part made of a resin containing the above flame retardant is left at high temperatures for a long period of time, an aluminum 20 wiring on a semiconductor device is corroded under the influence of free bromine, which causes malfunctioning of the electronic part and causes a problem that the reliability at high temperatures is degraded. For overcoming the above problems, there has been proposed a 25 method in which a metal hydroxide is added as a flame retardant. In the above method, however, it is required to incorporate a large amount of the metal hydroxide (at least 40 % by weight). Further, electronic parts are 30 exposed to a high temperature (generally, 215 to 260oC), and there is caused a problem that the metal hydroxide having a high water absorptivity causes the swelling or cracking of a semiconductor device due to sharp gasification of water absorbed into the metal hydroxide. 4 Further, there is caused another problem that the metal hydroxide decreases the soldering resistance. There is still another problem that the function of an electronic part decreases under a high-temperature and high-5 humidity environment having a temperature of 80 to 200°C and a relative humidity of 70 to 100 %. For overcoming the above problem, JP-A-9-176368 proposes a composition, in which the metal hydroxide is limited to magnesium hydroxide and the magnesium 10 hydroxide is surface-treated to prevent water absorption and improve its dispersibility in a resin. According to technological innovation in the field of electronic parts in recent years, however, it is required to attain higher flame retardancy, higher 15 humidity resistance and higher safety. Further, when magnesium hydroxide particles have a high content of impurities, such as an Fe compound and Mn compound in particular, they cause a resin to thermally deteriorate. Further, an accumulated charge amount decreases due to a 20 recent increase in the memory capacity, that is, an increase in integration degree of a memory. When the content of radioactive substances such as uranium (U), thorium (Th), etc., is large, therefore, there is caused a problem that the memory suffers a soft error due to a- 25 ray generated by disintegration of U, Th, etc. For example, the content of U and Th in a 1 M to 4 M bit memory is required to be 1 ppb (ng/g) or less, and the content of U and Th in a 4 to 16 M bit memory is required to be 0.1 ppb (ng/g) or less, for ensuring 30 reliability against the soft error. When a synthetic resin is to be used as a sealing material, therefore, the content of the radioactive substances in magnesium hydroxide to be incorporated into the synthetic resin comes to be required to be very small, that is, the radiation of a-ray from the synthetic resin is required to be low. It has been also found that a water-soluble alkali metal salt in magnesium hydroxide particles affects 5 water resistance and insulation. According to studies made by the present inventors, it has been accordingly found that, when a predetermined amount of high-purity magnesium hydroxide particles containing an Fe compound, Mn compound, U compound and 10 Th compound as impurities in amounts equivalent to, or Smaller than, predetermined amount and having an average secondary particle diameter of 5 µm or less and a specific surface area (BET) of 10 m2/g or less and, optionally, a predetermined amount of other inorganic 15 filler are incorporated into a synthetic resin, there can be obtained a resin composition for electronic parts and a molded article, the resin composition having sufficient water resistance under high-temperature and high-humidity conditions, having anti-corrosion 20 properties for a mold and an electronic part, being excellent in in flame retardancy and thermal conductivity and serving to prevent the occurrence of a soft error of a memory. The present invention has been made on the basis of 25 the above finding. That is, according to the present invention, there is provided a thermosetting resin composition for electric and electronic machines and equipment, comprising (a) a thermosetting resin and (b) magnesium hydroxide particles, the magnesium hydroxide 30 particles satisfying the following requirements (i) to (iv), (i) the average secondary particle diameter, measured by a laser diffraction scattering method, is 0.5 to 5 µm. (ii) the BET specific surface area is 0.1 to 10 m2/g, (iii) the total content of an Fe compound and an Mn compound as metals is 0.02 % by weight or less, and (iv) the total content of a U compound and a Th 5 compound as metals is 10 ppb or less. The present invention will be explained more in detail hereinafter. Magnesium hydroxide particles not only causes the thermal conductivity to decrease but also causes the 10 thermal stability of an incorporated resin to greatly decrease with—an increase in the content of an iron compound and a manganese compound in the magnesium hydroxide. However, it does not mean that the physical properties of the resin are not impaired so long as the 15 total content of these compounds satisfies the above range. It is also required that the above average secondary particle diameter and the above specific surface area should satisfy the above ranges, respectively. With an increase in the average secondary 20 particle diameter of the particles, the area of contact to the resin decreases, and the thermal stability improves. However, there is caused a problem that the mechanical strength decreases or that the appearance is poor. The average secondary particle diameter of the 25 magnesium hydroxide is 0.5 to 5 µm, preferably 0.7 to 3 µm. The BET specific surface area of the magnesium hydroxide particles is 0.1 to 10 m2/g, preferably 0.2 to 5 m2/g. Further, the total content of a U compound and a 30 Th compound as metals is required to satisfy 10 ppb or less, preferably 5 ppb or less, more preferably 1 ppb or less. Further, desirably, the content of a water-soluble alkali metal salt is 0.05 % by weight or less, preferably 0.03 % by weight, more preferably 0.003 % by 7 weight or less. An Fe compound and an Mn compound have an influence on the thermal deterioration of the resin when the content thereof exceeds the above upper limit. Further, 5 when the content of an U compound and a Th compound is within the above range, the occurrence of a soft error of a memory can be decreased, and with an increase in the content thereof, the frequency of a soft error increases. 10 As described above, magnesium hydroxide particles can give a resin composition that satisfies various properties such as compatibility with a resin, dispersibility, moldability, processability, an appearance, mechanical strength and flame retardancy of 15 a molded article and a decrease in the occurrence of soft errors of a memory, so long as the average secondary particle diameter, the specific surface area, the total content of an iron compound and a manganese compound, the total content of a U compound and Th 20 compound and, desirably, the content of a water-soluble alkali metal salt are within the above ranges. The method of preparation of the above magnesium hydroxide particles in the present invention is not specially limited so long as the magnesium hydroxide 25 particles satisfy the above requirements (i), (ii), (iii) and (iv). The magnesium hydroxide particles that satisfy the above (i) average secondary particle diameter and the above (ii) specific surface area can be prepared, for 30 example, by employing basically the method and conditions described in JP-A-52-115799. That is, the magnesium hydroxide particles can be prepared by providing, as raw materials, magnesium chloride or magnesium nitrate and an alkali substance such as an 8 alkali metal hydroxide, ammonia, magnesium oxide or the like and heating them in an aqueous medium under pressure conditions (preferably 5 to 30 kg/cm2) . In this case, raw materials containing no or little impurities, 5 particularly, such as an iron compound, a manganese compound (and the other above metal compound if necessary), U and Th compounds, etc., are selected, whereby there can be obtained magnesium hydroxide particles that satisfy the above requirements (iii) and 10 (iv). Further, as apparatuses such as a reactor, a purifier, a crystallizer, a dryer, a milling machine, etc., it is required to select apparatuses made of an anti-corrosive material free of elution and inclusion of the above metals. 15 Preferably, the magnesium chloride or magnesium nitrate and the above alkali substance as raw materials are purified for decreasing the content of the above impurities therein as required. The water-soluble alkali metal salt can be removed 20 by washing the thus-obtained magnesium hydroxide particles with ion-exchanged water or industrial water. The present inventors have made studies for a method of removing U and Th, and as a result, it has been found that it is proper to employ a method in which U in the 25 raw materials for magnesium hydroxide is removed by adsorption with a hydrotalcite of the following formula (1), Mg2+1-xM3+x(OH)2A2-x/2-mH20 (1) wherein M3+ is at least one of Al3+ and Fe3+, 30 x is a positive number of 0.2 A2" is at least one of C032" and S042", and m is a number of 0 to 2. The above hydrotalcite may be a natural product or a synthetic product, and more preferably, it is added to 9 the raw materials for magnesium hydroxide, to remove a U compound. There may be employed a method in which a hydrotalcite is synthesized from a magnesium source that is a raw material for magnesium hydroxide and an 5 aluminum source, the synthesized hydrotalcite is filtered, and a magnesium chloride that is a filtrate is used as a raw material for magnesium hydroxide. In this case, the synthesized hydrotalcite has already adsorbed a U compound, so that magnesium chloride containing 10 little U compound can be obtained. One example is as follows. 2 Liters of a bittern (MgCl2 = 1.9 mol/L) (having a U content of 126 ppb) was placed in a 3-liter beaker, and 2 ml of hydrochloric acid (supplied by Wako 15 Purechemical K.K.) having a concentration adjusted to 5 N was added with stirring. The mixture was stirred at room temperature (25°C) for 30 minutes, to give a bittern having a pH of 1.6. To this bittern was added 20 ml of an aluminum nitrate (supplied by Wako Purechemical 20 K.K.) aqueous solution having a concentration adjusted to 54 g/L with stirring, and further, 23 ml of aqueous ammonia (supplied by Wako Purechemical K.K.) having a concentration of 14 % by weight was dropwise added with stirring. Then, the mixture was stirred at room 25 temperature (25°C) for 30 minutes, to give a bittern having a pH of 6.5. The above bittern is a suspension containing a double hydroxide formed by co-precipitation of aluminum ion and part of magnesium ion. The above bittern was 30 filtration by means of suction with a Buchner funnel, to give a bittern of magnesium chloride (MgCl2) = 1.7 mol/L as a filtrate. The content of U was 0.8 ng/ml or less. The above magnesium chloride was used as a Mg source, 10 calcium hydroxide was used as an alkali source, and these were reacted, to give magnesium hydroxide. The magnesium hydroxide had a U content of 2 ppb. The above U removing treatment can also remove Th at the same time. 5 The above U content was compared with the U content of magnesium hydroxide obtained by reacting magnesium chloride that was not subjected to U removing treatment with calcium hydroxide. Table 1 The mechanism of removing uranium and thorium is not clear. However, it is assumed that magnesium hydroxide particles undergo crystal growth, so that the BET 15 specific surface area decreases and that the particles are improved in dispersibility, whereby the particles are imparted with power properties suitable as an additive for a resin. The magnesium hydroxide particles for use in the 20 present invention may be surface-treated beforehand with at least one surface-treating agent selected from the group consisting of a higher fatty acid, an anionic surfactant, phosphate esters, a coupling agent and fatty acid esters of polyhydric alcohol. 25 Examples of the surface-treating agent that can be desirably used are as follows. Higher fatty acids having at least 10 carbon atoms such as stearic acid, erucic acid, palmitic acid, lauric acid and behenic acid and alkali metal salts of the above higher fatty acids; 30 sulfuric acid esters and salts of higher alcohols such 11 as stearyl alcohol and oleyl alcohol; anionic surfactants such as sulfuric acid ester and salt of polyethylene glycol ether, amide-bonded sulfuric acid ester and salt, ester-bonded sulfuric acid ester and 5 salt, ester-bonded sulfonate, amide-bonded sulfonic acid salt, ether-bonded sulfonic acid salt, ether-bonded alkylarylsulfonic acid salt, ester-bonded alkylarylsulfonic acid salt and amide-bonded alkylarylsulfonic acid salt; phosphate esters which are 10 mono- or diester of orthophosphoric acid and oleyl alcohol or stearyl alcohol or a mixture of these esters and are phosphate esters of acid types, alkali metal salts or amine salts thereof; silane coupling agents such as γ-(2-aminoethyl)aminopropyltrimethoxysilane, y- 15 (2-aminoethyl)aminopropylmethyldimethoxysilane, y-methacryloxypropyltrimethoxysilane, N-{β- (N-vinylbenzylaminoethyl) -y-aminopropyltrimethoxysilane-hydrochloride, y-glycidoxypropyltrimethoxysilane, y-mercaptopropyltrimethoxysilane, methyltrimethoxysilane, 20 methyltriethoxysilane, vinyltriacetoxysilane, y- chloropropyltrimethoxysilane, hexamethyldisilazane, y-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride, y-chloropropylmethyldimethoxysilane, y- 25 mercaptopropylmethyldimethoxysilane, methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(p-methoxyethoxy)silane, p-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, y- 30 glycidoxypropylmethylethoxysilane, y-glycidoxypropyltriethoxysilane, y-methacryloxypropylmethyldimethoxysilane, y-methacryloxypropylmethyldiethoxysilane, y-methacryloxypropyltriethoxysilane, N-p(aminoethyl)y- IX aminopropylmethyldimethoxysilane, N-\|3(aminoethyl)y-aminopropyltrimethoxyslane, N-(3(aminoethyl)y-aminopropyltriethoxyslane, y-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-y-5 aminopropyltrimethoxysilane, y- glycidoxypropyltrimethoxysilane and y- methacryloxypropyltrimethoxysilane; titanate-containing coupling agents such as isopropyltriisostearoyl titanate, isopropyltris(dioctylpyrophosphate) titanate, 10 isopropyl(N-aminoethyl-aminoethyl) titanate, isopropyltridecylbenzenesulfonyl titanate, tetraoctylbis(ditridecylphosphite) titanate, bis(dioctylpyrophosphate)oxyacetate titanate, isopropyltridecylbenzenesulfonyl titanate, 15 tetraisopropylbis(dioctylphosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis-(ditridecyl)phosphite titanate, bis(dioctylpyrophosphate)ethylene titanate, isopropyltrioctanoyl titanate, isopropyldimethacryloylisostearoyl titanate, 20 isopropylisostearoyldiacryl titanate, isopropyltri(dioctylphosphate) titanate, isopropyltricumylphenyl titanate, dicumylphenyloxyacetate titanate and diisostearoylethylene titanate; aluminum-containing 25 coupling agents such as acetoalkoxyaluminum diisopropylate; triphenyl phosphite, diphenyl-tridecyl phosphite, phenyl-ditridecyl phosphite, phenyl-isodecyl phosphite, tri-nonylphenyl phosphite, 4,4"-butylidene-bis(3-methyl-6-t-butylphenyl)-ditridecyl phosphite, 30 trilaurylthiophosphite, and polyhydric alcohols and fatty acids such as glycerin monostearate and glycerin monooleate. The magnesium hydroxide particles can be surface-treated with the above surface-treating agent by a wet 13 13 or dry method that is known per se. The wet method can be carried out. for example, by adding the surface-treating agent in the state of a liquid or an emulsion to a slurry of the magnesium hydroxide particles and 5 mechanically fully stirring the mixture at a temperature that does not exceed approximately 100°C. The dry method can be carried out by adding the surface-treating agent in the state of a liquid, an emulsion or a solid while the magnesium hydroxide 10 particles are fully stirred with a mixer such as a Henschel mixer, and fully mixing them under heat or without heating. While the amount of the surface-treating agent can be determined as required, the amount of the surface-treating agent based on the magnesium 15 hydroxide particles is 0.01 to 10 % by weight, preferably 0.05 to 5 % by weight. The surface-treated magnesium hydroxide particles can be brought into the form of an end product by employing means of washing with water, dehydration, 20 granulation, drying, pulverization, classification, etc., as required. Further, the above surface-treating agent may be added during the kneading of a synthetic resin and the magnesium hydroxide particles. In the resin composition of the present invention, 25 the amount ratio of the above (a) thermosetting resin and (b) magnesium hydroxide particles is follows. The amount of the (b) magnesium hydroxide particles per 100 parts by weight of the (a) thermosetting resin is 5 to 500 parts by weight, preferably 50 to 300 parts by 30 weight. Further, the resin composition of the present invention may contain (c) an inorganic filler other than the (b) magnesium hydroxide particles as required. The (c) inorganic filler is incorporated for improving 14 strength or decreasing water absorption. When the (c) inorganic filler is incorporated in the present invention, examples thereof include amorphous silica, crystalline silica, calcium carbonate, magnesium 5 carbonate, alumina, magnesia, silicon nitride, magnesium aluminum oxide, zirconia, zircon, clay, talc, wollastonite, calcium silicate, titanium oxide, antimony oxide, asbestos, glass fiber, calcium sulfate and aluminum nitride. These may have any form of spheres, 10 pulverized products or fibers. Specific examples of the (c) inorganic filler preferably include amorphous silica, crystalline silica and alumina. The amount of the (c) inorganic filler is properly determined such that the total amount of the (b) magnesium hydroxide particles 15 and the (c) inorganic filler based on the entire resin composition is in the range of from 60 to 95 % by weight, preferably from 70 to 90 % by weight. The (c) inorganic filler is required to have excellent moldability, that is, excellent flowability and a low viscosity. 20 The thermosetting resin in the present invention can be selected from resins that are used as/in a semiconductor sealant or a laminated substrate, a multi-layered circuit board and a printed wiring board for electronic parts. Specifically, the thermosetting resin 25 includes an epoxy resin, a silicone resin, a phenolic resin, a diarylphthalate resin, a urea resin, a melamine resin and an alkyd resin. Of these, an epoxy resin is preferred. While the epoxy resin in the present invention is 30 not specially limited, examples thereof are as follows. (1) Bisphenol type epoxy resins such as a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a 2,2",6,6"-tetramethylbisphenol A type epoxy resin, a bisphenol S type epoxy resin, a bisphenol AD type epoxy resin and a tetramethyl bisphenol A type epoxy resin; (2) A bisphenol type epoxy resin, other difunctional epoxy resins such as a bisphenolhexafluoroacetone diglycidyl ether, bis-fJ- 5 trifluoromethyldiglycidylbisphenol A and resorcino- diglycidyl ether and polyfunctional epoxy resins having a naphthalene skeleton or a dicyclopentadiene skeleton; (3) A 1,6-diglycidyloxynaphthalene type epoxy resin, and naphthalene-containing epoxy resins such as l-(2,7- 10 diglycidyloxynaphthyl)-1-(2-glycidyloxynaphthyl)methane, l,l-bis(2,7-diglycidyloxynaphthyl)methan and 1,1-bis(2,7-diglycidyloxynaphthyl)-1-phenyl-methane; (4) Novolak type epoxy resins such as a phenol-novolak type epoxy resin, a cresol-novolak type epoxy resin, an 15 o-cresol-novolak type epoxy resin, bisphenol A novolak type epoxy resin, a bisphenol AD novolak type epoxy resin, a brominated phenol-novolak type epoxy resin, a brominated bisphenol A novolak type epoxy resin, and a salicylaldehyde novolak type epoxy resin; 20 (5) an epoxy resin formed by copolymerization of the above bisphenol type epoxy resin and the above novolak type epoxy resin through bisphenol and/or halogenated bisphenol; (6) Alicyclic aliphatic epoxy resins typified by an 25 epoxidized product of a poly-adduct of dicyclopentadiene and phenol; (7) Glycidyl ester type epoxy resins and diglycidyl ester type epoxy resins such as diglycidyl phthalate ester, diglycidyl tetrahydrophthalate ester, diglycidyl 30 hexahydrophthalate ester, diglycidyl p-hydroxybenzoate, glycidyl dimer acid ester and triglycidyl ester; (8) Glycidylamine type epoxy resins such as tetraglycidylaminodiphenylmethane, triglycidyl p- aminophenol and tetraglycidyl m-xylenediamine, a 16 hydantoin type epoxy resin, and heterocyclic epoxy resins such as triglycidyl isosyanurate; (9) Glycidyl ether type epoxy resins such as fluoroglycinol triglycidyl ether, trihydroxybiphenyl 5 triglycidyl ether, trihydroxyphenylmethane triglycidyl ether, glycerin triglycidyl ether, 2-[4-(2,3-epoxypropoxy)phenyl]-2-[4-[1,1-bis[4-(2,3-epoxypropoxy)phenyl]ethyl]phenyl]propane, 1,3-bis[4-[1-[4-(2,3-epoxypropoxy)phenyl]-l-[4-[l-[4-(2,3- 10 epoxypropoxy)phenyl]-1- methylethyl]phenyl]ethyl]phenoxy]-2-propanol, tetrahydroxyphenylethane tetraglycidyl ether, tetraglycidylbenzophenone and bisresorcinol tetraglycidyl ether, and biphenyl type epoxy resins such 15 as tetraglycidoxybiephenyl; (10) An alicyclic epoxy resin, an isocyanate type epoxy resin, an aliphatic linear epoxy resin, N-glycidyl compounds from halides, hydrides, aromatic amines and heterocyclic nitrogen bases thereof such as N,N- 20 diglycidylaniline, triglycidyl isocyanurate and N,N,N",N"-tetraglycidyl-bis(p-aminophenyl)-methane, a triphenolmethane type epoxy resin and an aralakyl-group-containing epoxy resin. Further, the thermosetting resin includes various 25 modified epoxy resins obtained by reacting the above epoxy resins with a polymer obtained from a monomer such as a silicon oligomer having a functional group such as an epoxy group, a carboxyl group or an amino group, acrylonitrile, butadiene or isoprene or a polyamide 30 resin. The above epoxy resins may be used alone, may be used as a mixture of at least two epoxy resins or may be used in combination with a modified epoxy resin. A curing agent for the thermosetting resin is not critical. For example, the curing agent can be selected 17 from an amine-containing curing agent, an acid-anhydride -containing curing agent, a novolak resin or an oligomer curing agent as required. Specific examples of the curing agent are as follows. 5 Specifically, first, examples of the amine-containing curing agent are as follows. Apliphatic polyamines such as diethylenetriamine, triethylenetetramine, tetraethylpentamine, dipropylenetriamine, bis(hexamethylene)triamine, 1,3,6- 10 trisaminomethylhexane, trimethylhexamethylenediamine, diethylaminopropylamine, menthenediamine, isophoronediamine and bis(4-amino-3- methylcyclohexyl)methane; aromatic diamines such as m-xylylenediamine, m-phenylenediamine, 15 diaminodiphenylmethane, diaminodiphenylsulfone, benzyldimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol and tri-2-ethylhexylic acid salt of 2,4,6-tris(dimethylaminomethyl)phenol; 20 Dicyandiamide, organic acid hydrazide of dicyandiamide and guanidine compounds such as trimethylguanidine and dimethylguanidine; Imidazoles such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2- 25 heptadecylimidazole, 2-phenylimidazole and 1-benzyl-2-methylimidazole; Other cycloamines such as piperidine, N-aminoethylpiperazine, N,N"-dimethylpiperazine, pyridinepicoline, 3,9-bis(3-aminopropyl)-2,4,8,10- 30 tetraspiro[5,5]undecane, l,4-diazadicyclo(2,2,2)octane and 1,8-diazabicycloundecane (DBU); Polyether-based amines such as dioxyethylenediamine, trioxyethylenediamine, polyoxyethylenediamine, a polyamine-ethylene oxide adduct and a polyamine- propylene oxide adduct; Alaknolamines such as trimethanolamine, triethanolamine and diethanolamine; A diamine having a main chain formed of a silicone 5 skeleton, a polyamine epoxy resin adduct, a cyanoethylated polyamine, a ketimine compound, a 1-cyanoethyl-form compound, and a trimellitate salt, quaternary salt, isocyanurate salt and hydroxymethy-form compound of a 1-cyanoethyl-form compound; and 10 Other potential amine-containing curing agents such as a boron trifluoride-amine complex, diaminomaleonitrile, a diaminomaleonitrile derivative, melamine and a melamine derivative. Examples of the acid-anhydride-containing curing 15 agent include aromatic acid anhydrides such as phthalic acid anhydride, trimellitic acid anhydride, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), pyromellitic acid anhydride and 3,3",4,4-benzophenonetetracarboxylic acid anhydride, 20 maleic acid anhydride, succinic acid anhydride, tetrahydrophthalic acid anhydride, methyltetrahydrophthalic acid, methylnadic acid anhydride, alkenylsuccinic acid anhydride, hexahydrophthalic acid anhydride, 25 methylhexahydrophthalic acid anhydride, methylcyclohexenyltetracarboxylic acid anhydride, methyl esters of adducts, etc., of linoleic aicd, linolenic acid or eleostearic acid with maleic acid anhydride, alicyclic acid anhydrides of adducts, etc., of 30 triglyceride with maleic acid anhydride; linear aliphatic acid anhydrides such as polyadipic acid anhydride, polyazelaic acid anhydride and polysebacic acid anhydride; and halogenated acid anhydrides such as chlorendic acid anhydride and tetrabromophthalic acid anhydride. The oligomer curing agent includes novolak type phenolic resins such as a phenol novolak resin, a cresol novolak resin, a BPA novolak resin, a biphenol novolak 5 resin and halogen-substituted compounds of these, an amino resin, a resole type phenolic resin, an aniline-formalin resin and a polyvinyl phenolic resin. In addition to these, the curing agent includes photo-setting and ultraviolet-light-curing agents such 10 as an aromatic diazonium salt, a diallyliodonium salt, a triallylsulfonium salt, a triallylselenium salt, acridine orange, benzoflavin and cetoflavin T, and polymercaptan-containing curing agents such as polymercaptan and a polysulfide resin. The amount of the 15 curing agent per 100 parts by weight of the thermosetting resin is 10 to 200 parts by weight, preferably 50 to 150 parts by weight. A cure promoter can be selected from known cure promoters. For example, it can be selected from a Lewis 20 acid, an amine complex, an imidazole compound, an organic phosphorus compound, a tertiary amine or a quaternary ammonium salt. Specific examples of the cure promoter include acrylonitrile having an imino group, isocyanate, me1amine and imidazole masked with an 25 acrylate or an epoxy group. Examples of the above imidazole compound include imidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 4,5-diphenylimidazole, 2- 30 methylimidazoline, 2-ethyl-4-methylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2-heptadecylimidazoline, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-phenyl-4-methylimidazole, 2-ethylimidazoline, 2-isopropylimidazoline, 2,4- dimethylimidazoline and 2-phenyl-4-methylimidazoline. The masking agent is selected from acrylonitrile, phenylenediisocyanate, toluenediisocyanate, naphthalenediisocyanate, hexamethylenediisocyanate, 5 methylenebisphenylisocyanate, melamine aerylate or various epoxy resins. The cure promoter also includes diazabicycloalkenes such as 1,8- diazabicyclo(5,4,0)undecene-7 and derivatives thereof; tertiary amines such as triethylenediamine, 10 benzyldimethylamine, triethanolamine, dimethylaminoethanol and tris(dimethylaminomethyl)phenol; organic phosphines such as tributylphosphine, methyldiphenylphosphine and triphenylphosphine; tetraphenylborates such as tetra- 15 substituted phosphonium-tetra-substituted borate, e.g., tetraphenylphosphonium-tetraphenyl borate, 2-ethyl-4-methylimidazole-tetraphenyl borate and N-methylmorpholine-tetraphenyl borate. These curing agents may be used alone or in combination. 20 For forming a solder resist in the process of fabricating a printed wiring board, a photo-printing method is employed, and it is recent practice to carry out double-side simultaneous exposure. A composite laminated board is therefore required to transmit no 25 ultraviolet light, for complying with the double-side simultaneous exposure. As an ultraviolet-non-transmitting laminated board, there are known a laminated board using a matrix resin containing an ultraviolet absorbent and a laminated 30 board using a glass fiber substrate to which an ultraviolet shielding agent is adhered. An organic ultraviolet shielding agent to be incorporated into the matrix resin is selected from organic ultraviolet absorbents such as hydroxybenzophenones, hydroxybenzotriazoles, a diaminostyrylbenzylsulfonic acid derivative, an imidazole derivative or a coumarin derivative. The above organic ultraviolet absorbents include 2-hydroxy-4-octoxybenzophenone, 2-(2-hydroxy-5-5 methyl-phenyl)benzotriazole, 4-methyl-7- dimethylaminocoumarin, bis-(1,5-diphenylpyrazolin-3-yl)-styrene and 1-(phenyl)-3,3-(4-tert-butyl-styryl)-5-(4-tert-butyl-phenyl)-pyrazoline. An inorganic ultraviolet shielding agent is selected, 10 for example, from ZnxAl203+x (x = 1 to 10), titanium oxide, clay or calcium carbonate. These may be used in combination. The content of the ultraviolet absorbent or the ultraviolet shielding agent based on the resin 15 composition is preferably 0.001 to 2 % by weight. When the above content is less than 0.001 % by weight, there is no or little effect. When it exceeds 2 % by weight, discoloration takes place under heat. The resin composition of the present invention may 20 contain a mold release agent such as a curing natural wax, a synthetic wax, a higher fatty acid, a metal salt thereof or paraffin; a colorant such as carbon black, a pigment, a foaming agent, a plasticizer, a filler, an acid receptor, a reinforcing agent, an antioxidant, an 25 anti-static agent, a lubricant, a stabilizer and a cure promoter. For decreasing a stress, various elastomers may be added or may be used after they are reacted in advance. Specific examples thereof include addition type or 30 reaction type elastomers such as polybutadiene, a butadiene-acrylonitrile copolymer, a silicone rubber and a silicone oil. In the resin composition of the present invention, preferably, components are mixed by melti-kneading them, and the resin composition is produced by melt-kneading components by a known kneading method using, for example, a kneader, a roll single-screw or twin-screw extruder or a co-kneader. The resin composition of the present invention is 5 generally used in the form of a powder or tablets when it is molded into an electronic part. For example, as a method of molding the resin composition for forming an electronic part in which a semiconductor is fixed on a substrate, generally, there is employed a low-pressure 10 transfer molding method, and an injection molding method and a compression molding method may be also used. As molding conditions, for example, the resin composition is molded at a molding temperature of 150°C to 200°C, under a pressure of 5 to 15 MPa for a molding time 15 period of 30 to 300 seconds, and a cured product of the resin composition is formed, whereby a sealed-semiconductor molded product is produced. Further, the above molded product may be additionally heat-treated at 100 to 200°C for 2 to 15 hours as required. 20 Examples In Examples, "%" and "part" stand for "% by weight" and "part by weight" unless otherwise specified. In Examples, magnesium hydroxide particles were measured 25 for properties, and molded products were measured for physical properties, by the following methods. For molding, transfer molding was carried out. (1) Average secondary particle diameter of magnesium hydroxide particles 30 Measured and determined with a MICROTRAC particle size analyzer SPA type (supplied by LEEDS & NORTHRUP INSTRUMENTS). A sample powder in an amount of 700 mg is added to 70 ml of water, the mixture is ultrasonically dispersed 23 (MODEL US-300, electric current 300 µA, supplied by NISSEI) for 3 minutes, then, 2 to 4 ml of a dispersion is sampled and added to a sample chamber of the above particle size analyzer provided with degassed water of 5 250 ml, the analyzer is operated to circulate the suspension for 8 minutes, and then the suspension is measured for a particle size distribution. The measurement was carried out twice, and an arithmetic mean of 50 % accumulated secondary particle diameters 10 obtained by the measurements is calculated and used as an average secondary particle diameter of the sample. (2) BET specific surface area of magnesium hydroxide particles Measured by a liquid nitrogen adsorption method. 15 (3) Content of U and Th Measured by ICP-MS (Inductivity Coupled Plasma-Mass Spectrometry) or atomic absorption spectrophotometry. (4) Contents of water-soluble alkali metal salt and chlorine (CI) 20 Measured by atomic absorption spectrophotometry. (5) Content of heavy metal Measured by ICP mass analysis method. (6) Flame retardancy Measured according to a UL 94VE method. 25 (7) Thermal conductivity Measured by a probe method using a QTM quick thermal conductivity meter supplied by Kyoto Denshi Kogyo K.K. (8) Thermal stability Apparatus: Gear oven GPHH-100 supplied by TABAI 30 ESPEC. CO. Condition setting: 1508C, a damper opening 50 % Two test pieces are used as one set, upper portions thereof are sandwiched with paper and clipped by metallic clip, and the test pieces were suspended from a rotary ring and taken off with the passage of time. Test piece: 1/12 inch Evaluation: A time period that passed before the test pieces were found to show whitening was used as an 5 index for thermal deterioration. (9) Water resistance and insulation of a molded product A test piece having the form of a rectangular parallelepiped having a square form having four sides 10 cm long each as a plan view and a thickness of 2 mm was 10 prepared by cutting a product of a synthetic resin. The test piece was immersed in an ion-exchanged water at 95°C for 48 hours and then taken out, water on the surface was wiped off with a paper towel, and the test piece was re-conditioned at 23° C±2° C at 50 %RH for 15 15 minutes. This test piece was measured for a volume specific resistance with TR8401 supplied by Takeda Riken Kogyo K.K. under the same re-conditioning above, to obtain data of water resistance and insulation. On the other hand, a test piece of EVA was immersed in ion- 20 exchanged water at 70°C for 168 hours. (10) Heat resistance against soldering Evaluated according to JIS C6481. A sample was boiled in water for 2 hours to carry out water absorption treatment and then floated in a soldering 25 bath at 260°C for 180 seconds, and an appearance thereof was evaluated for defects. (11) Water absorptivity A weight change was measured under conditions of 85°C and 85 %RH in a constant-temperature constant-30 humidity chamber (AGX-326 supplied by Advantec Toyo). Table 2 shows properties of magnesium hydroxide particles (A-l to A-5) used in Examples. A-2 and A-3 were magnesium hydroxide particles that were surface-treated to A-l. Whether or not magnesium hydroxide particles were surface-treated and what surface-treating agent was used are as shown below. When a surface-treating agent was used, the amount thereof was 2 % by weight based on 5 magnesium hydroxide particles. Magnesium hydroxide particles Surface treatment A-l No A-2 Stearic acid 10 A-3 Epoxy silanecoupling agent A-4 No A-5 No WE CLAIM: 1. A thermosetting resin composition suitable for producing moulded articles suitable for electric and electronic appliances, comprising (a) a thermosetting resin and (b) magnesium hydroxide particles, the magnesium hydroxide particles satisfying the following requirements (i) to (iv), (i) the average secondary particle diameter, measured by a laser diffraction scattering method, is 0.5 to 5 urn, (ii) the BET specific surface area is 0.1 to 10 m2/g, (iii) the total content of Fe and Mn as metal is 0.02 % by weight or less, and (iv) the total content of U and Th as metal is 10 ppb or less. 2. The thermosetting resin composition as claimed in claim 1, wherein the magnesium hydroxide particles have an average secondary particle diameter, measured by a laser diffraction scattering method, of 0.7 to 3 µm. 3. The thermosetting resin composition as claimed in claim 1, wherein the magnesium hydroxide particles have a BET specific surface area of 0.2 to 5 m2/g. 4. The thermosetting resin composition as claimed in claim 1, wherein the total content of iron and manganese as metals in the magnesium hydroxide particles is 0.01 % by weight or less. -33- 5. The thermosetting resin composition as claimed in claim 1, wherein the total content of U and Th as metals in the magnesium hydroxide particles is 5 ppb or less. 6. The thermosetting resin composition as claimed in claim 1, wherein the total content of U and Th as metals in the magnesium hydroxide particles is 1 ppb or less. 7. The thermosetting resin composition as claimed in claim 1, wherein the magnesium hydroxide particles have a water-soluble alkali metal compound, the total content, as alkali metals, of 0.05 % by weight or less. 8. The thermosetting resin composition as claimed in claim 1, wherein the magnesium hydroxide particles have a water-soluble alkali metal compound total content, as alkali metals, of 0.03% by weight or less. 9. The thermosetting resin composition as claimed in claim 1, wherein the magnesium hydroxide particles have a water-soluble alkali metal compound, the total content, as alkali metals, of 0.003 % by weight or less. 10. The thermosetting resin composition as claimed in claim 1, wherein the thermosetting resin is an epoxy resin, a silicone resin, a phenolic resin, a diaryl phthalate resin, a urea resin, melamine resin, or an alkyd resin. 11. The thermosetting resin composition as claimed in claim 1, wherein the thermosetting resin is an epoxy resin. -34- 12. The thermosetting resin composition as claimed in claim 1, wherein the magnesium hydroxide particles are particles that are surface-treated with at least one surface-treating agent selected from the group consisting of high fatty acids, anionic surfactans, phosphate esters, silicones, coupling agents and fatty acid esters of polyhydric alcohols. 13. The thermosetting resin composition as claimed in claim 1, which contains 5 to 500 parts by weight of the magnesium hydroxide particles per 100 parts by weight of the thermosetting resin. 14. The thermosetting resin composition as claimed in claim 1, which contains 50 to 300 parts by weight of the magnesium hydroxide particles per 100 parts by weight of the thermosetting resin. 15. The thermosetting resin composition as claimed in claim 1, containing an inorganic filler other than the magnesium hydroxide particles and the total content of magnesium hydroxide particles and inorganic filler being 60 to 95 % by weight based on the resin composition. 16. The thermosetting resin composition as claimed in claim 1, containing 10 to 200 parts by weight of a known curing agent per 100 parts by weight of the thermosetting resin. 17. The thermosetting resin composition as claimed in claim 1, containing 0.001 to 2% by weight of a known ultraviolet absorbent or an ultraviolet shielding agent based on the resin composition. -35- 18. A molded article such as a laminated electronic substrate, multilayered circuit board and product wiring board obtained by curing and molding a thermosetting composition as claimed in claims 1 to 18.

Full Text

The present invention relates to a thermosetting resin composition suitable for producing moulded articles suitable for electric and electronic appliances.
Field of the Invention
The present invention relates to a thermosetting resin composition excellent particularly in flame retardancy, heat resistance and water resistance for electric and electronic devices. Further, the present invention also relates to molded articles formed by curing such a resin composition, particularly to sealing, coating or insulation of a part, a laminated board and a metal-clad laminated board for electric and electronic devices, such as a sealed molded article, a prepreg, a multi-layered circuit substrate and a laminated board for a circuit substrate.
A semiconductor device and an integrated circuit device are sealed with various sealing materials for preventing influences caused by external vibrations, impact, dust, water and ambient gas. While a metal material, ceramic, glass, etc., have been used as sealing materials, a thermosetting resin is recently used for the sealing in most cases from the viewpoint of a cost and mass-productivity.
With technological innovation in the field of semiconductors, the integration degree has increased, devices have decreased in size and wirings have come be finer and finer. Packages tend to decrease in size and thickness as well, and sealing materials are accordingly required to have high reliability. Further, the sealing materials are required to have strength and thermal conductivity, and it is general practice to use resins containing inorganic fillers.
-2-

Thermosetting resins typified by an epoxy resin are excellent in mechanical strength, electrical properties, thermal properties, adhesion, chemical durability and water resistance, so that they are applied to various 5 laminated boards formed in combination with glass, cloth, paper or synthetic fibers, such as a laminated board for a structure, a laminated board for heavy electric machines and equipment, a printed wiring board and a laminated metal board for a printed wiring board.
10 These electric and electronic parts are decreasing in size and thickness and have come to have high performances due to technological innovation. Therefore, it is required to decrease the size and thickness of semiconductor devices constituting the electric and
15 electronic parts and multi-layered printed wiring boards on which such parts are to be mounted, and they are required to attain high performances and to have high reliability.
For the above reason, the mounting method of a
20 multi-layered printed wiring board is shifting from a pin-insertion type package to a surface-mounting type package and further to a bare chip mounting method in which a chip is directly mounted, so that a high adhesion of a resin is required. The high adhesion of a
25 resin can be attained by decreasing water absorption of the resin. A laminated board for a circuit board is processed under high-temperature and high-humidity conditions during the fabrication of the laminated board and mounting of electronic parts and then subjected to
30 the step of soldering by dipping it in a soldering bath, so that the laminated board is liable to undergo swelling or peeling. Therefore, the resin is required to have high heat resistance, high flame retardancy and long-term stability.
3

The above thermosetting resin used for sealing semiconductor devices or in the printed wiring board or laminated board (to be generally sometimes referred to as "electronic part" hereinafter) is required to have 5 high flame retardancy, and for this purpose, it is
general practice to employ a method in which a bromine-containing epoxy resin and antimony oxide are incorporated into the resin. However, this method causes a problem that hydrogen bromide, bromine-containing gas,
10 antimony bromide, etc., are generated during combustion to do harm to human bodies and corrode a machine and equipment, and also causes an environmental safety problem on disposal of industrial wastes resulting from the process of producing electronic parts and disposal
15 of an epoxy resin molding material and electronic parts produced from such a molding material.
Further, when an electronic part made of a resin containing the above flame retardant is left at high temperatures for a long period of time, an aluminum
20 wiring on a semiconductor device is corroded under the influence of free bromine, which causes malfunctioning of the electronic part and causes a problem that the reliability at high temperatures is degraded. For overcoming the above problems, there has been proposed a
25 method in which a metal hydroxide is added as a flame retardant.
In the above method, however, it is required to incorporate a large amount of the metal hydroxide (at least 40 % by weight). Further, electronic parts are
30 exposed to a high temperature (generally, 215 to 260oC), and there is caused a problem that the metal hydroxide having a high water absorptivity causes the swelling or cracking of a semiconductor device due to sharp gasification of water absorbed into the metal hydroxide.
4

Further, there is caused another problem that the metal hydroxide decreases the soldering resistance. There is still another problem that the function of an electronic part decreases under a high-temperature and high-5 humidity environment having a temperature of 80 to 200°C and a relative humidity of 70 to 100 %.
For overcoming the above problem, JP-A-9-176368 proposes a composition, in which the metal hydroxide is limited to magnesium hydroxide and the magnesium
10 hydroxide is surface-treated to prevent water absorption and improve its dispersibility in a resin.
According to technological innovation in the field of electronic parts in recent years, however, it is required to attain higher flame retardancy, higher
15 humidity resistance and higher safety. Further, when magnesium hydroxide particles have a high content of impurities, such as an Fe compound and Mn compound in particular, they cause a resin to thermally deteriorate. Further, an accumulated charge amount decreases due to a
20 recent increase in the memory capacity, that is, an increase in integration degree of a memory. When the content of radioactive substances such as uranium (U), thorium (Th), etc., is large, therefore, there is caused a problem that the memory suffers a soft error due to a-
25 ray generated by disintegration of U, Th, etc. For example, the content of U and Th in a 1 M to 4 M bit memory is required to be 1 ppb (ng/g) or less, and the content of U and Th in a 4 to 16 M bit memory is required to be 0.1 ppb (ng/g) or less, for ensuring
30 reliability against the soft error. When a synthetic resin is to be used as a sealing material, therefore, the content of the radioactive substances in magnesium hydroxide to be incorporated into the synthetic resin comes to be required to be very small, that is, the

radiation of a-ray from the synthetic resin is required to be low.
It has been also found that a water-soluble alkali metal salt in magnesium hydroxide particles affects 5 water resistance and insulation.
According to studies made by the present inventors, it has been accordingly found that, when a predetermined amount of high-purity magnesium hydroxide particles containing an Fe compound, Mn compound, U compound and
10 Th compound as impurities in amounts equivalent to, or Smaller than, predetermined amount and having an average secondary particle diameter of 5 µm or less and a specific surface area (BET) of 10 m2/g or less and, optionally, a predetermined amount of other inorganic
15 filler are incorporated into a synthetic resin, there
can be obtained a resin composition for electronic parts and a molded article, the resin composition having sufficient water resistance under high-temperature and high-humidity conditions, having anti-corrosion
20 properties for a mold and an electronic part, being excellent in in flame retardancy and thermal conductivity and serving to prevent the occurrence of a soft error of a memory.
The present invention has been made on the basis of
25 the above finding. That is, according to the present invention, there is provided a thermosetting resin composition for electric and electronic machines and equipment, comprising (a) a thermosetting resin and (b) magnesium hydroxide particles, the magnesium hydroxide
30 particles satisfying the following requirements (i) to (iv),
(i) the average secondary particle diameter, measured by a laser diffraction scattering method, is 0.5 to 5 µm.

(ii) the BET specific surface area is 0.1 to 10 m2/g, (iii) the total content of an Fe compound and an Mn compound as metals is 0.02 % by weight or less, and (iv) the total content of a U compound and a Th 5 compound as metals is 10 ppb or less.
The present invention will be explained more in detail hereinafter.
Magnesium hydroxide particles not only causes the thermal conductivity to decrease but also causes the 10 thermal stability of an incorporated resin to greatly decrease with—an increase in the content of an iron compound and a manganese compound in the magnesium hydroxide. However, it does not mean that the physical properties of the resin are not impaired so long as the 15 total content of these compounds satisfies the above range. It is also required that the above average secondary particle diameter and the above specific surface area should satisfy the above ranges, respectively. With an increase in the average secondary 20 particle diameter of the particles, the area of contact to the resin decreases, and the thermal stability improves. However, there is caused a problem that the mechanical strength decreases or that the appearance is poor. The average secondary particle diameter of the 25 magnesium hydroxide is 0.5 to 5 µm, preferably 0.7 to 3 µm.
The BET specific surface area of the magnesium hydroxide particles is 0.1 to 10 m2/g, preferably 0.2 to 5 m2/g. Further, the total content of a U compound and a 30 Th compound as metals is required to satisfy 10 ppb or less, preferably 5 ppb or less, more preferably 1 ppb or less. Further, desirably, the content of a water-soluble alkali metal salt is 0.05 % by weight or less, preferably 0.03 % by weight, more preferably 0.003 % by
7

weight or less.
An Fe compound and an Mn compound have an influence on the thermal deterioration of the resin when the content thereof exceeds the above upper limit. Further, 5 when the content of an U compound and a Th compound is within the above range, the occurrence of a soft error of a memory can be decreased, and with an increase in the content thereof, the frequency of a soft error increases.
10 As described above, magnesium hydroxide particles can give a resin composition that satisfies various properties such as compatibility with a resin, dispersibility, moldability, processability, an appearance, mechanical strength and flame retardancy of
15 a molded article and a decrease in the occurrence of soft errors of a memory, so long as the average secondary particle diameter, the specific surface area, the total content of an iron compound and a manganese compound, the total content of a U compound and Th
20 compound and, desirably, the content of a water-soluble alkali metal salt are within the above ranges.
The method of preparation of the above magnesium hydroxide particles in the present invention is not specially limited so long as the magnesium hydroxide
25 particles satisfy the above requirements (i), (ii), (iii) and (iv).
The magnesium hydroxide particles that satisfy the above (i) average secondary particle diameter and the above (ii) specific surface area can be prepared, for
30 example, by employing basically the method and
conditions described in JP-A-52-115799. That is, the magnesium hydroxide particles can be prepared by providing, as raw materials, magnesium chloride or magnesium nitrate and an alkali substance such as an
8

alkali metal hydroxide, ammonia, magnesium oxide or the like and heating them in an aqueous medium under pressure conditions (preferably 5 to 30 kg/cm2) . In this case, raw materials containing no or little impurities, 5 particularly, such as an iron compound, a manganese compound (and the other above metal compound if necessary), U and Th compounds, etc., are selected, whereby there can be obtained magnesium hydroxide particles that satisfy the above requirements (iii) and
10 (iv). Further, as apparatuses such as a reactor, a purifier, a crystallizer, a dryer, a milling machine, etc., it is required to select apparatuses made of an anti-corrosive material free of elution and inclusion of the above metals.
15 Preferably, the magnesium chloride or magnesium
nitrate and the above alkali substance as raw materials are purified for decreasing the content of the above impurities therein as required.
The water-soluble alkali metal salt can be removed
20 by washing the thus-obtained magnesium hydroxide
particles with ion-exchanged water or industrial water.
The present inventors have made studies for a method of removing U and Th, and as a result, it has been found that it is proper to employ a method in which U in the
25 raw materials for magnesium hydroxide is removed by
adsorption with a hydrotalcite of the following formula
(1),
Mg2+1-xM3+x(OH)2A2-x/2-mH20 (1)
wherein M3+ is at least one of Al3+ and Fe3+,
30 x is a positive number of 0.2 A2" is at least one of C032" and S042", and
m is a number of 0 to 2.
The above hydrotalcite may be a natural product or a synthetic product, and more preferably, it is added to
9

the raw materials for magnesium hydroxide, to remove a U compound. There may be employed a method in which a hydrotalcite is synthesized from a magnesium source that is a raw material for magnesium hydroxide and an 5 aluminum source, the synthesized hydrotalcite is
filtered, and a magnesium chloride that is a filtrate is used as a raw material for magnesium hydroxide. In this case, the synthesized hydrotalcite has already adsorbed a U compound, so that magnesium chloride containing
10 little U compound can be obtained. One example is as follows.
2 Liters of a bittern (MgCl2 = 1.9 mol/L) (having a U content of 126 ppb) was placed in a 3-liter beaker, and 2 ml of hydrochloric acid (supplied by Wako
15 Purechemical K.K.) having a concentration adjusted to 5 N was added with stirring. The mixture was stirred at room temperature (25°C) for 30 minutes, to give a bittern having a pH of 1.6. To this bittern was added 20 ml of an aluminum nitrate (supplied by Wako Purechemical
20 K.K.) aqueous solution having a concentration adjusted to 54 g/L with stirring, and further, 23 ml of aqueous ammonia (supplied by Wako Purechemical K.K.) having a concentration of 14 % by weight was dropwise added with stirring. Then, the mixture was stirred at room
25 temperature (25°C) for 30 minutes, to give a bittern having a pH of 6.5.
The above bittern is a suspension containing a double hydroxide formed by co-precipitation of aluminum ion and part of magnesium ion. The above bittern was
30 filtration by means of suction with a Buchner funnel, to give a bittern of magnesium chloride (MgCl2) = 1.7 mol/L as a filtrate.
The content of U was 0.8 ng/ml or less. The above magnesium chloride was used as a Mg source,
10

calcium hydroxide was used as an alkali source, and these were reacted, to give magnesium hydroxide. The magnesium hydroxide had a U content of 2 ppb. The above U removing treatment can also remove Th at the same time. 5 The above U content was compared with the U content of magnesium hydroxide obtained by reacting magnesium chloride that was not subjected to U removing treatment with calcium hydroxide.
Table 1

The mechanism of removing uranium and thorium is not clear. However, it is assumed that magnesium hydroxide particles undergo crystal growth, so that the BET
15 specific surface area decreases and that the particles are improved in dispersibility, whereby the particles are imparted with power properties suitable as an additive for a resin.
The magnesium hydroxide particles for use in the
20 present invention may be surface-treated beforehand with at least one surface-treating agent selected from the group consisting of a higher fatty acid, an anionic surfactant, phosphate esters, a coupling agent and fatty acid esters of polyhydric alcohol.
25 Examples of the surface-treating agent that can be desirably used are as follows. Higher fatty acids having at least 10 carbon atoms such as stearic acid, erucic acid, palmitic acid, lauric acid and behenic acid and alkali metal salts of the above higher fatty acids;
30 sulfuric acid esters and salts of higher alcohols such
11

as stearyl alcohol and oleyl alcohol; anionic surfactants such as sulfuric acid ester and salt of polyethylene glycol ether, amide-bonded sulfuric acid ester and salt, ester-bonded sulfuric acid ester and 5 salt, ester-bonded sulfonate, amide-bonded sulfonic acid salt, ether-bonded sulfonic acid salt, ether-bonded alkylarylsulfonic acid salt, ester-bonded alkylarylsulfonic acid salt and amide-bonded alkylarylsulfonic acid salt; phosphate esters which are
10 mono- or diester of orthophosphoric acid and oleyl
alcohol or stearyl alcohol or a mixture of these esters and are phosphate esters of acid types, alkali metal salts or amine salts thereof; silane coupling agents such as γ-(2-aminoethyl)aminopropyltrimethoxysilane, y-
15 (2-aminoethyl)aminopropylmethyldimethoxysilane, y-methacryloxypropyltrimethoxysilane, N-{β- (N-vinylbenzylaminoethyl) -y-aminopropyltrimethoxysilane-hydrochloride, y-glycidoxypropyltrimethoxysilane, y-mercaptopropyltrimethoxysilane, methyltrimethoxysilane,
20 methyltriethoxysilane, vinyltriacetoxysilane, y-
chloropropyltrimethoxysilane, hexamethyldisilazane, y-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride, y-chloropropylmethyldimethoxysilane, y-
25 mercaptopropylmethyldimethoxysilane,
methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris(p-methoxyethoxy)silane, p-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, y-
30 glycidoxypropylmethylethoxysilane, y-glycidoxypropyltriethoxysilane, y-methacryloxypropylmethyldimethoxysilane, y-methacryloxypropylmethyldiethoxysilane, y-methacryloxypropyltriethoxysilane, N-p(aminoethyl)y-
IX

aminopropylmethyldimethoxysilane, N-|3(aminoethyl)y-aminopropyltrimethoxyslane, N-(3(aminoethyl)y-aminopropyltriethoxyslane, y-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-y-5 aminopropyltrimethoxysilane, y-
glycidoxypropyltrimethoxysilane and y-
methacryloxypropyltrimethoxysilane; titanate-containing coupling agents such as isopropyltriisostearoyl titanate, isopropyltris(dioctylpyrophosphate) titanate,
10 isopropyl(N-aminoethyl-aminoethyl) titanate, isopropyltridecylbenzenesulfonyl titanate, tetraoctylbis(ditridecylphosphite) titanate, bis(dioctylpyrophosphate)oxyacetate titanate, isopropyltridecylbenzenesulfonyl titanate,
15 tetraisopropylbis(dioctylphosphite) titanate, tetra(2,2-diallyloxymethyl-1-butyl)bis-(ditridecyl)phosphite titanate, bis(dioctylpyrophosphate)ethylene titanate, isopropyltrioctanoyl titanate, isopropyldimethacryloylisostearoyl titanate,
20 isopropylisostearoyldiacryl titanate,
isopropyltri(dioctylphosphate) titanate, isopropyltricumylphenyl titanate, dicumylphenyloxyacetate titanate and diisostearoylethylene titanate; aluminum-containing
25 coupling agents such as acetoalkoxyaluminum
diisopropylate; triphenyl phosphite, diphenyl-tridecyl phosphite, phenyl-ditridecyl phosphite, phenyl-isodecyl phosphite, tri-nonylphenyl phosphite, 4,4"-butylidene-bis(3-methyl-6-t-butylphenyl)-ditridecyl phosphite,
30 trilaurylthiophosphite, and polyhydric alcohols and
fatty acids such as glycerin monostearate and glycerin monooleate.
The magnesium hydroxide particles can be surface-treated with the above surface-treating agent by a wet
13

13
or dry method that is known per se. The wet method can be carried out. for example, by adding the surface-treating agent in the state of a liquid or an emulsion to a slurry of the magnesium hydroxide particles and 5 mechanically fully stirring the mixture at a temperature that does not exceed approximately 100°C.
The dry method can be carried out by adding the surface-treating agent in the state of a liquid, an emulsion or a solid while the magnesium hydroxide
10 particles are fully stirred with a mixer such as a Henschel mixer, and fully mixing them under heat or without heating. While the amount of the surface-treating agent can be determined as required, the amount of the surface-treating agent based on the magnesium
15 hydroxide particles is 0.01 to 10 % by weight, preferably 0.05 to 5 % by weight.
The surface-treated magnesium hydroxide particles can be brought into the form of an end product by employing means of washing with water, dehydration,
20 granulation, drying, pulverization, classification, etc., as required. Further, the above surface-treating agent may be added during the kneading of a synthetic resin and the magnesium hydroxide particles.
In the resin composition of the present invention,
25 the amount ratio of the above (a) thermosetting resin and (b) magnesium hydroxide particles is follows. The amount of the (b) magnesium hydroxide particles per 100 parts by weight of the (a) thermosetting resin is 5 to 500 parts by weight, preferably 50 to 300 parts by
30 weight.
Further, the resin composition of the present invention may contain (c) an inorganic filler other than the (b) magnesium hydroxide particles as required. The (c) inorganic filler is incorporated for improving
14

strength or decreasing water absorption. When the (c) inorganic filler is incorporated in the present invention, examples thereof include amorphous silica, crystalline silica, calcium carbonate, magnesium 5 carbonate, alumina, magnesia, silicon nitride, magnesium aluminum oxide, zirconia, zircon, clay, talc, wollastonite, calcium silicate, titanium oxide, antimony oxide, asbestos, glass fiber, calcium sulfate and aluminum nitride. These may have any form of spheres,
10 pulverized products or fibers. Specific examples of the (c) inorganic filler preferably include amorphous silica, crystalline silica and alumina. The amount of the (c) inorganic filler is properly determined such that the total amount of the (b) magnesium hydroxide particles
15 and the (c) inorganic filler based on the entire resin
composition is in the range of from 60 to 95 % by weight, preferably from 70 to 90 % by weight. The (c) inorganic filler is required to have excellent moldability, that is, excellent flowability and a low viscosity.
20 The thermosetting resin in the present invention can be selected from resins that are used as/in a semiconductor sealant or a laminated substrate, a multi-layered circuit board and a printed wiring board for electronic parts. Specifically, the thermosetting resin
25 includes an epoxy resin, a silicone resin, a phenolic
resin, a diarylphthalate resin, a urea resin, a melamine resin and an alkyd resin. Of these, an epoxy resin is preferred.
While the epoxy resin in the present invention is
30 not specially limited, examples thereof are as follows. (1) Bisphenol type epoxy resins such as a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a 2,2",6,6"-tetramethylbisphenol A type epoxy resin, a bisphenol S type epoxy resin, a bisphenol AD type epoxy

resin and a tetramethyl bisphenol A type epoxy resin;
(2) A bisphenol type epoxy resin, other difunctional
epoxy resins such as a bisphenolhexafluoroacetone
diglycidyl ether, bis-fJ-
5 trifluoromethyldiglycidylbisphenol A and resorcino-
diglycidyl ether and polyfunctional epoxy resins having a naphthalene skeleton or a dicyclopentadiene skeleton;
(3) A 1,6-diglycidyloxynaphthalene type epoxy resin, and
naphthalene-containing epoxy resins such as l-(2,7-
10 diglycidyloxynaphthyl)-1-(2-glycidyloxynaphthyl)methane, l,l-bis(2,7-diglycidyloxynaphthyl)methan and 1,1-bis(2,7-diglycidyloxynaphthyl)-1-phenyl-methane;
(4) Novolak type epoxy resins such as a phenol-novolak
type epoxy resin, a cresol-novolak type epoxy resin, an
15 o-cresol-novolak type epoxy resin, bisphenol A novolak type epoxy resin, a bisphenol AD novolak type epoxy resin, a brominated phenol-novolak type epoxy resin, a brominated bisphenol A novolak type epoxy resin, and a salicylaldehyde novolak type epoxy resin;
20 (5) an epoxy resin formed by copolymerization of the above bisphenol type epoxy resin and the above novolak type epoxy resin through bisphenol and/or halogenated bisphenol;
(6) Alicyclic aliphatic epoxy resins typified by an
25 epoxidized product of a poly-adduct of dicyclopentadiene and phenol;
(7) Glycidyl ester type epoxy resins and diglycidyl
ester type epoxy resins such as diglycidyl phthalate
ester, diglycidyl tetrahydrophthalate ester, diglycidyl
30 hexahydrophthalate ester, diglycidyl p-hydroxybenzoate, glycidyl dimer acid ester and triglycidyl ester;
(8) Glycidylamine type epoxy resins such as
tetraglycidylaminodiphenylmethane, triglycidyl p-
aminophenol and tetraglycidyl m-xylenediamine, a

16
hydantoin type epoxy resin, and heterocyclic epoxy resins such as triglycidyl isosyanurate;
(9) Glycidyl ether type epoxy resins such as
fluoroglycinol triglycidyl ether, trihydroxybiphenyl 5 triglycidyl ether, trihydroxyphenylmethane triglycidyl ether, glycerin triglycidyl ether, 2-[4-(2,3-epoxypropoxy)phenyl]-2-[4-[1,1-bis[4-(2,3-epoxypropoxy)phenyl]ethyl]phenyl]propane, 1,3-bis[4-[1-[4-(2,3-epoxypropoxy)phenyl]-l-[4-[l-[4-(2,3-
10 epoxypropoxy)phenyl]-1-
methylethyl]phenyl]ethyl]phenoxy]-2-propanol, tetrahydroxyphenylethane tetraglycidyl ether, tetraglycidylbenzophenone and bisresorcinol tetraglycidyl ether, and biphenyl type epoxy resins such
15 as tetraglycidoxybiephenyl;
(10) An alicyclic epoxy resin, an isocyanate type epoxy
resin, an aliphatic linear epoxy resin, N-glycidyl
compounds from halides, hydrides, aromatic amines and
heterocyclic nitrogen bases thereof such as N,N-
20 diglycidylaniline, triglycidyl isocyanurate and
N,N,N",N"-tetraglycidyl-bis(p-aminophenyl)-methane, a triphenolmethane type epoxy resin and an aralakyl-group-containing epoxy resin.
Further, the thermosetting resin includes various
25 modified epoxy resins obtained by reacting the above
epoxy resins with a polymer obtained from a monomer such as a silicon oligomer having a functional group such as an epoxy group, a carboxyl group or an amino group, acrylonitrile, butadiene or isoprene or a polyamide
30 resin. The above epoxy resins may be used alone, may be used as a mixture of at least two epoxy resins or may be used in combination with a modified epoxy resin.
A curing agent for the thermosetting resin is not critical. For example, the curing agent can be selected
17

from an amine-containing curing agent, an acid-anhydride -containing curing agent, a novolak resin or an oligomer curing agent as required. Specific examples of the curing agent are as follows. 5 Specifically, first, examples of the amine-containing curing agent are as follows. Apliphatic polyamines such as diethylenetriamine, triethylenetetramine, tetraethylpentamine, dipropylenetriamine, bis(hexamethylene)triamine, 1,3,6-
10 trisaminomethylhexane, trimethylhexamethylenediamine, diethylaminopropylamine, menthenediamine, isophoronediamine and bis(4-amino-3-
methylcyclohexyl)methane; aromatic diamines such as m-xylylenediamine, m-phenylenediamine,
15 diaminodiphenylmethane, diaminodiphenylsulfone,
benzyldimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol and tri-2-ethylhexylic acid salt of 2,4,6-tris(dimethylaminomethyl)phenol;
20 Dicyandiamide, organic acid hydrazide of dicyandiamide and guanidine compounds such as trimethylguanidine and dimethylguanidine;
Imidazoles such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 2-
25 heptadecylimidazole, 2-phenylimidazole and 1-benzyl-2-methylimidazole;
Other cycloamines such as piperidine, N-aminoethylpiperazine, N,N"-dimethylpiperazine, pyridinepicoline, 3,9-bis(3-aminopropyl)-2,4,8,10-
30 tetraspiro[5,5]undecane, l,4-diazadicyclo(2,2,2)octane and 1,8-diazabicycloundecane (DBU);
Polyether-based amines such as dioxyethylenediamine, trioxyethylenediamine, polyoxyethylenediamine, a polyamine-ethylene oxide adduct and a polyamine-

propylene oxide adduct;
Alaknolamines such as trimethanolamine, triethanolamine and diethanolamine;
A diamine having a main chain formed of a silicone 5 skeleton, a polyamine epoxy resin adduct, a
cyanoethylated polyamine, a ketimine compound, a 1-cyanoethyl-form compound, and a trimellitate salt, quaternary salt, isocyanurate salt and hydroxymethy-form compound of a 1-cyanoethyl-form compound; and
10 Other potential amine-containing curing agents such as a boron trifluoride-amine complex,
diaminomaleonitrile, a diaminomaleonitrile derivative, melamine and a melamine derivative.
Examples of the acid-anhydride-containing curing
15 agent include aromatic acid anhydrides such as phthalic acid anhydride, trimellitic acid anhydride, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), pyromellitic acid anhydride and 3,3",4,4-benzophenonetetracarboxylic acid anhydride,
20 maleic acid anhydride, succinic acid anhydride, tetrahydrophthalic acid anhydride, methyltetrahydrophthalic acid, methylnadic acid anhydride, alkenylsuccinic acid anhydride, hexahydrophthalic acid anhydride,
25 methylhexahydrophthalic acid anhydride,
methylcyclohexenyltetracarboxylic acid anhydride, methyl esters of adducts, etc., of linoleic aicd, linolenic acid or eleostearic acid with maleic acid anhydride, alicyclic acid anhydrides of adducts, etc., of
30 triglyceride with maleic acid anhydride; linear
aliphatic acid anhydrides such as polyadipic acid anhydride, polyazelaic acid anhydride and polysebacic acid anhydride; and halogenated acid anhydrides such as chlorendic acid anhydride and tetrabromophthalic acid

anhydride.
The oligomer curing agent includes novolak type phenolic resins such as a phenol novolak resin, a cresol novolak resin, a BPA novolak resin, a biphenol novolak 5 resin and halogen-substituted compounds of these, an amino resin, a resole type phenolic resin, an aniline-formalin resin and a polyvinyl phenolic resin.
In addition to these, the curing agent includes photo-setting and ultraviolet-light-curing agents such
10 as an aromatic diazonium salt, a diallyliodonium salt, a triallylsulfonium salt, a triallylselenium salt, acridine orange, benzoflavin and cetoflavin T, and polymercaptan-containing curing agents such as polymercaptan and a polysulfide resin. The amount of the
15 curing agent per 100 parts by weight of the
thermosetting resin is 10 to 200 parts by weight, preferably 50 to 150 parts by weight.
A cure promoter can be selected from known cure promoters. For example, it can be selected from a Lewis
20 acid, an amine complex, an imidazole compound, an organic phosphorus compound, a tertiary amine or a quaternary ammonium salt. Specific examples of the cure promoter include acrylonitrile having an imino group, isocyanate, me1amine and imidazole masked with an
25 acrylate or an epoxy group. Examples of the above
imidazole compound include imidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 4,5-diphenylimidazole, 2-
30 methylimidazoline, 2-ethyl-4-methylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2-heptadecylimidazoline, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-phenyl-4-methylimidazole, 2-ethylimidazoline, 2-isopropylimidazoline, 2,4-

dimethylimidazoline and 2-phenyl-4-methylimidazoline. The masking agent is selected from acrylonitrile, phenylenediisocyanate, toluenediisocyanate, naphthalenediisocyanate, hexamethylenediisocyanate, 5 methylenebisphenylisocyanate, melamine aerylate or
various epoxy resins. The cure promoter also includes diazabicycloalkenes such as 1,8-
diazabicyclo(5,4,0)undecene-7 and derivatives thereof; tertiary amines such as triethylenediamine,
10 benzyldimethylamine, triethanolamine, dimethylaminoethanol and
tris(dimethylaminomethyl)phenol; organic phosphines such as tributylphosphine, methyldiphenylphosphine and triphenylphosphine; tetraphenylborates such as tetra-
15 substituted phosphonium-tetra-substituted borate, e.g., tetraphenylphosphonium-tetraphenyl borate, 2-ethyl-4-methylimidazole-tetraphenyl borate and N-methylmorpholine-tetraphenyl borate. These curing agents may be used alone or in combination.
20 For forming a solder resist in the process of
fabricating a printed wiring board, a photo-printing method is employed, and it is recent practice to carry out double-side simultaneous exposure. A composite laminated board is therefore required to transmit no
25 ultraviolet light, for complying with the double-side simultaneous exposure.
As an ultraviolet-non-transmitting laminated board, there are known a laminated board using a matrix resin containing an ultraviolet absorbent and a laminated
30 board using a glass fiber substrate to which an
ultraviolet shielding agent is adhered. An organic ultraviolet shielding agent to be incorporated into the matrix resin is selected from organic ultraviolet absorbents such as hydroxybenzophenones,

hydroxybenzotriazoles, a diaminostyrylbenzylsulfonic acid derivative, an imidazole derivative or a coumarin derivative. The above organic ultraviolet absorbents include 2-hydroxy-4-octoxybenzophenone, 2-(2-hydroxy-5-5 methyl-phenyl)benzotriazole, 4-methyl-7-
dimethylaminocoumarin, bis-(1,5-diphenylpyrazolin-3-yl)-styrene and 1-(phenyl)-3,3-(4-tert-butyl-styryl)-5-(4-tert-butyl-phenyl)-pyrazoline.
An inorganic ultraviolet shielding agent is selected,
10 for example, from ZnxAl203+x (x = 1 to 10), titanium oxide, clay or calcium carbonate. These may be used in combination.
The content of the ultraviolet absorbent or the ultraviolet shielding agent based on the resin
15 composition is preferably 0.001 to 2 % by weight. When the above content is less than 0.001 % by weight, there is no or little effect. When it exceeds 2 % by weight, discoloration takes place under heat.
The resin composition of the present invention may
20 contain a mold release agent such as a curing natural wax, a synthetic wax, a higher fatty acid, a metal salt thereof or paraffin; a colorant such as carbon black, a pigment, a foaming agent, a plasticizer, a filler, an acid receptor, a reinforcing agent, an antioxidant, an
25 anti-static agent, a lubricant, a stabilizer and a cure promoter.
For decreasing a stress, various elastomers may be added or may be used after they are reacted in advance. Specific examples thereof include addition type or
30 reaction type elastomers such as polybutadiene, a
butadiene-acrylonitrile copolymer, a silicone rubber and a silicone oil. In the resin composition of the present invention, preferably, components are mixed by melti-kneading them, and the resin composition is produced by

melt-kneading components by a known kneading method using, for example, a kneader, a roll single-screw or twin-screw extruder or a co-kneader.
The resin composition of the present invention is 5 generally used in the form of a powder or tablets when it is molded into an electronic part. For example, as a method of molding the resin composition for forming an electronic part in which a semiconductor is fixed on a substrate, generally, there is employed a low-pressure
10 transfer molding method, and an injection molding method and a compression molding method may be also used. As molding conditions, for example, the resin composition is molded at a molding temperature of 150°C to 200°C, under a pressure of 5 to 15 MPa for a molding time
15 period of 30 to 300 seconds, and a cured product of the resin composition is formed, whereby a sealed-semiconductor molded product is produced. Further, the above molded product may be additionally heat-treated at 100 to 200°C for 2 to 15 hours as required.
20
Examples
In Examples, "%" and "part" stand for "% by weight" and "part by weight" unless otherwise specified. In Examples, magnesium hydroxide particles were measured
25 for properties, and molded products were measured for physical properties, by the following methods. For molding, transfer molding was carried out. (1) Average secondary particle diameter of magnesium hydroxide particles
30 Measured and determined with a MICROTRAC particle size analyzer SPA type (supplied by LEEDS & NORTHRUP INSTRUMENTS).
A sample powder in an amount of 700 mg is added to 70 ml of water, the mixture is ultrasonically dispersed
23

(MODEL US-300, electric current 300 µA, supplied by NISSEI) for 3 minutes, then, 2 to 4 ml of a dispersion is sampled and added to a sample chamber of the above particle size analyzer provided with degassed water of 5 250 ml, the analyzer is operated to circulate the suspension for 8 minutes, and then the suspension is measured for a particle size distribution. The measurement was carried out twice, and an arithmetic mean of 50 % accumulated secondary particle diameters 10 obtained by the measurements is calculated and used as an average secondary particle diameter of the sample. (2) BET specific surface area of magnesium hydroxide particles
Measured by a liquid nitrogen adsorption method. 15 (3) Content of U and Th
Measured by ICP-MS (Inductivity Coupled Plasma-Mass Spectrometry) or atomic absorption spectrophotometry.
(4) Contents of water-soluble alkali metal salt
and chlorine (CI) 20 Measured by atomic absorption spectrophotometry.
(5) Content of heavy metal
Measured by ICP mass analysis method.
(6) Flame retardancy
Measured according to a UL 94VE method. 25 (7) Thermal conductivity
Measured by a probe method using a QTM quick thermal conductivity meter supplied by Kyoto Denshi Kogyo K.K. (8) Thermal stability
Apparatus: Gear oven GPHH-100 supplied by TABAI 30 ESPEC. CO.
Condition setting: 1508C, a damper opening 50 %
Two test pieces are used as one set, upper portions thereof are sandwiched with paper and clipped by metallic clip, and the test pieces were suspended from a

rotary ring and taken off with the passage of time.
Test piece: 1/12 inch
Evaluation: A time period that passed before the test pieces were found to show whitening was used as an 5 index for thermal deterioration.
(9) Water resistance and insulation of a molded product
A test piece having the form of a rectangular parallelepiped having a square form having four sides 10 cm long each as a plan view and a thickness of 2 mm was
10 prepared by cutting a product of a synthetic resin. The test piece was immersed in an ion-exchanged water at 95°C for 48 hours and then taken out, water on the surface was wiped off with a paper towel, and the test piece was re-conditioned at 23° C±2° C at 50 %RH for 15
15 minutes. This test piece was measured for a volume
specific resistance with TR8401 supplied by Takeda Riken Kogyo K.K. under the same re-conditioning above, to obtain data of water resistance and insulation. On the other hand, a test piece of EVA was immersed in ion-
20 exchanged water at 70°C for 168 hours.
(10) Heat resistance against soldering
Evaluated according to JIS C6481. A sample was boiled in water for 2 hours to carry out water absorption treatment and then floated in a soldering 25 bath at 260°C for 180 seconds, and an appearance thereof was evaluated for defects.
(11) Water absorptivity
A weight change was measured under conditions of 85°C and 85 %RH in a constant-temperature constant-30 humidity chamber (AGX-326 supplied by Advantec Toyo).
Table 2 shows properties of magnesium hydroxide particles (A-l to A-5) used in Examples. A-2 and A-3 were magnesium hydroxide particles that were surface-treated to A-l.

Whether or not magnesium hydroxide particles were surface-treated and what surface-treating agent was used are as shown below. When a surface-treating agent was used, the amount thereof was 2 % by weight based on 5 magnesium hydroxide particles.
Magnesium hydroxide particles Surface treatment
A-l No
A-2 Stearic acid
10 A-3 Epoxy silanecoupling agent
A-4 No
A-5 No

WE CLAIM:
1. A thermosetting resin composition suitable for producing moulded articles
suitable for electric and electronic appliances, comprising (a) a thermosetting
resin and (b) magnesium hydroxide particles, the magnesium hydroxide
particles satisfying the following requirements (i) to (iv),
(i) the average secondary particle diameter, measured by a laser diffraction
scattering method, is 0.5 to 5 urn, (ii) the BET specific surface area is 0.1 to 10 m2/g,
(iii) the total content of Fe and Mn as metal is 0.02 % by weight or less, and (iv) the total content of U and Th as metal is 10 ppb or less.
2. The thermosetting resin composition as claimed in claim 1, wherein the magnesium hydroxide particles have an average secondary particle diameter, measured by a laser diffraction scattering method, of 0.7 to 3 µm.
3. The thermosetting resin composition as claimed in claim 1, wherein the magnesium hydroxide particles have a BET specific surface area of 0.2 to 5 m2/g.
4. The thermosetting resin composition as claimed in claim 1, wherein the total content of iron and manganese as metals in the magnesium hydroxide particles is 0.01 % by weight or less.
-33-

5. The thermosetting resin composition as claimed in claim 1, wherein the total content of U and Th as metals in the magnesium hydroxide particles is 5 ppb or less.
6. The thermosetting resin composition as claimed in claim 1, wherein the total content of U and Th as metals in the magnesium hydroxide particles is 1 ppb or less.
7. The thermosetting resin composition as claimed in claim 1, wherein the magnesium hydroxide particles have a water-soluble alkali metal compound, the total content, as alkali metals, of 0.05 % by weight or less.
8. The thermosetting resin composition as claimed in claim 1, wherein the magnesium hydroxide particles have a water-soluble alkali metal compound total content, as alkali metals, of 0.03% by weight or less.
9. The thermosetting resin composition as claimed in claim 1, wherein the magnesium hydroxide particles have a water-soluble alkali metal compound, the total content, as alkali metals, of 0.003 % by weight or less.
10. The thermosetting resin composition as claimed in claim 1, wherein the thermosetting resin is an epoxy resin, a silicone resin, a phenolic resin, a diaryl phthalate resin, a urea resin, melamine resin, or an alkyd resin.
11. The thermosetting resin composition as claimed in claim 1, wherein the thermosetting resin is an epoxy resin.
-34-

12. The thermosetting resin composition as claimed in claim 1, wherein the magnesium hydroxide particles are particles that are surface-treated with at least one surface-treating agent selected from the group consisting of high fatty acids, anionic surfactans, phosphate esters, silicones, coupling agents and fatty acid esters of polyhydric alcohols.
13. The thermosetting resin composition as claimed in claim 1, which contains 5 to 500 parts by weight of the magnesium hydroxide particles per 100 parts by weight of the thermosetting resin.
14. The thermosetting resin composition as claimed in claim 1, which contains 50 to 300 parts by weight of the magnesium hydroxide particles per 100 parts by weight of the thermosetting resin.
15. The thermosetting resin composition as claimed in claim 1, containing an inorganic filler other than the magnesium hydroxide particles and the total content of magnesium hydroxide particles and inorganic filler being 60 to 95 % by weight based on the resin composition.
16. The thermosetting resin composition as claimed in claim 1, containing 10 to 200 parts by weight of a known curing agent per 100 parts by weight of the thermosetting resin.
17. The thermosetting resin composition as claimed in claim 1, containing 0.001 to 2% by weight of a known ultraviolet absorbent or an ultraviolet shielding agent based on the resin composition.
-35-

18. A molded article such as a laminated electronic substrate, multilayered circuit board and product wiring board obtained by curing and molding a thermosetting composition as claimed in claims 1 to 18.

Documents:

in-pct-2002-0001-che abstract granted.pdf

in-pct-2002-0001-che claims granted.pdf

in-pct-2002-0001-che description (complete) granted.pdf

in-pct-2002-0001-che-abstract.pdf

in-pct-2002-0001-che-claim.pdf

in-pct-2002-0001-che-correspodence-others.pdf

in-pct-2002-0001-che-correspodence-po.pdf

in-pct-2002-0001-che-description (complete).pdf

in-pct-2002-0001-che-form-1.pdf

in-pct-2002-0001-che-form-19.pdf

in-pct-2002-0001-che-form-26.pdf

in-pct-2002-0001-che-form-3.pdf

in-pct-2002-0001-che-form-4.pdf

in-pct-2002-0001-che-form-5.pdf

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Patent Number

216451

Indian Patent Application Number

IN/PCT/2002/1/CHE

PG Journal Number

13/2008

Publication Date

31-Mar-2008

Grant Date

13-Mar-2008

Date of Filing

01-Jan-2002

Name of Patentee

KYOWA CHEMICAL INDUSTRY CO., LTD

Applicant Address

305, Yashimanishimachi, Takamatsu-shi, Kagawa 761-0113,

Inventors:

#	Inventor's Name	Inventor's Address
1	ANDO, Taro	C/O Research and Development of Kyowa Chemical Industry Co., Ltd., 4285, Hayashida-cho, Sakaide-shi, Kagawa-762-0012,
2	MANABE, Hitoshi	C/O Research and Development of Kyowa Chemical Industry Co., Ltd., 4285, Hayashida-cho, Sakaide-shi, Kagawa-762-0012,
3	SHIMIZU, Koji	C/O Research and Development of Kyowa Chemical Industry Co., Ltd., 4285, Hayashida-cho, Sakaide-shi, Kagawa-762-0012,

PCT International Classification Number

C08L 01/00

PCT International Application Number

PCT/JP01/03771

PCT International Filing date

2001-05-01

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	2000-133788	2000-05-02	Japan
2	2000-141962	2000-05-15	Japan