Epoxy resin, resin composition, and resin-encapsulated semiconductor device

Abstract: The stilbene epoxy resin having two different aryl groups of the following formula: wherein R 1 through R 8 independently represent acyclic or cyclic alkyl groups having 1 through 6 carbon atoms, hydrogen atom or halogen atoms, and the epoxy resin mixture including such stilbene epoxy resin according to the present invention have lower melting points than those of the stilbene epoxy resin having two identical aryl groups and the epoxy resin mixture including such stilbene epoxy resin. Compared with the conventional resins, the resin or resin mixture of the present invention accordingly has improved working and molding properties, thereby shortening the time required for the molding and working process and giving economical advantages and preferable productivity. The epoxy resin or resin mixture according to the present invention is preferably used as adhesive, coating, or insulating material, as electrical or electronic material for laminated sheets or the like, and especially as material for encapsulating electronic parts.

Description: FIELD OF THE INVENTION The present invention relates to a bisphenol preferably used as adhesive, coating, and electrical or electronic materials such as insulating materials or laminated sheets or the like, and especially as raw materials or intermediates of electronic parts, as well as to a method of manufacturing the same. The present invention also relates to an epoxy resin composition for encapsulating electronic parts and resin-encapsulated semiconductor device using the same. BACKGROUND OF THE INVENTION As the economically advantageous process for encapsulating semiconductor devices, such as LSIs, ICs, and transistors, transfer molding of the epoxy resin composition is typically adopted. Recently, resin-encapsulated LSIs are directly soaked in a solder bath for surface mounting. In the surface mounting process, the encapsulating material is exposed to the temperature of 200 °C or even higher. The water absorbed in the encapsulating material is accordingly expanded and causes cracks in the encapsulating package of the semiconductor devices. The epoxy resin encapsulating material is accordingly required to have low moisture absorption characteristics and improved cracking resistance. Widely used encapsulating material includes glycidyl ether of o-cresol novolak as an epoxy resin and phenol novolak as a curing agent. Such encapsulating material is stored under the condition of moisture-resistant packaging to avoid the above problems. To solve the above mentioned problems, especially to obtain low moisture absorption characteristics, low viscosity epoxy resins which can contain large amount of fillers have been developed and used for practical applications; for example, a glycidyl ether epoxy resin having a tetramethylbiphenyl skeleton. To improve the physical properties of the encapsulating material, the technique of improving the mechanical properties of cured resin is effective. A known method of improving the mechanical properties of cured objects of thermosetting resin controls the molecular orientation in the cured objects. There is a prior art related to the stilbene skeleton-containing epoxy resin. It has been reported that polymerization of a liquid crystal properties-possessing epoxy compound in the liquid crystal state in the presence of a small quantity of catalyst gives a crosslinked body retaining the liquid crystal structure and that polymerization in an electric field of specific conditions give rise to orientate the liquid crystal domain (see page 182 in the Proceedings of the 3rd Next-generation Industrial Infrastructure Technology Symposium (1985)). In this report, epoxidized 4,4'-dihydroxy-&A-cyanostilbene is shown as an example of the compound having liquid crystal properties. Some epoxy compounds including the rod-like structure of carbon-carbon double bond, carbon-nitrogen double bond, nitrogen-nitrogen double bond, or the like, which is different from the structure of the present invention, have been proposed as compounds possessing the excellent physical properties in JP-A-01-056 721 and JP-A-01-085 215. A method for manufacturing structural members was proposed, in which the structural members were cured with using a compound having a liquid crystal properties-donating component in the molecular structure thereof, while maintaining the liquid crystal structure, thereby improving the mechanical properties. (US Patent No. 4,762,901, German Patent No. 3,622,613, Japanese Patent Laid-open No. S-63-23931). A glycidyl ether of bisphenol compound having a non-substituted or alkyl group-substituted stilbene skeleton, or preferably having a stilbene skeleton with symmetrically substituted methyl groups, is given just as an example of such liquid crystal properties-containing compounds with other known compounds. Some stilbene bisphenol compounds having identical aryl substituents bound to the carbon-carbon double bond have also been reported previously. Preparation and physical properties of the compounds, such as 4,4'-dihydroxystilbene, 4,4'-dihydroxy-3,3'-dimethylstilben e, 4,4'-dihydroxy-3,3',5,5'-tetramethylstilbene, have been disclosed (von Rolf H. Sieber, Liebigs Ann.Chem. 730,31-46(1969)). A method of preparing 4,4'-dihydroxy-&A-methylstilbene has been described in METHODEN DER ORGANISCHEN CHEMIE (HOUBEN-WEYL) BAND IV/1c Phenol Teil 2 P1034. Epoxy resins having liquid crystal properties or the rod-like structure for the improved mechanical properties have also been proposed (EP-A-0 379 057). Given examples of hydroxyl group-containing compounds for epoxidation are 4,4'-dihydroxy-&A-methylstilb ene, 4,4'-dihydroxystilbene, 4,4'-dihydroxy-3,3',5,5'-tetra bromostilbene, and 4,4'-dihydroxy-3,3',5,5'-tetramethylstil bene. Resin compositions of the epoxy resin having the liquid crystal properties-developing functional group or the rod-like structure and the compound having active hydrogen have also been proposed for improving the physical properties (see EP-A-0 478 918 and EP-A-0 379 057). In the specifications of these patents or patent application, orientation of molecules in a cured object with the given epoxy compound has been proposed in order to improve the physical properties of the cured object. Conventional resins for encapsulant, for example, encapsulating materials comprising a glycidyl ether of o-cresol novolak, have substantially-balanced heat resistance and molding properties, but possess poorer physical properties as encapsulant than those of biphenyl epoxy resins. The biphenyl epoxy resins, while having low moisture absorption characteristics and excellent physical properties as the encapsulating material for surface mounting, on the other hand, have undesirably low heat resistance and cause package cracks under high humidity condition. The conventional stilbene epoxy resins show excellent curing properties but have high melting points and poorer working properties in the process of mixing the epoxy resin component with inorganic fillers or in the molding process. For example, glycidyl ethers of 4,4'-dihydroxystilbene, 4,4'-dihydroxy-3,3'-dimethylstilbene, and 4,4'-dihydroxy-3, 3',5,5'-tetramethylstilbene have high melting points of 208 to 215 °C, 150 °C, and 151 °C, respectively, and suffer from rather bad working properties. In fact, the epoxy resin of 4,4'-dihydroxystilbene can not be used for encapsulating semiconductor under the conditions set in the current production equipment. Semiconductor-encapsulating materials including thermosetting resins are formed to packages within a time period of 60 through 90 seconds. The cured objects of such material have a three-dimensional crosslinked structure without any specific molecular orientation as disclosed in the prior art described above. The prior arts above have been proposed to further improve the physical properties of cured objects by introducing a specific orientation to the cured structure. To introduce the liquid crystal state or the specific molecular orientation to cured objects, molding under the specified temperature conditions or external control of the molding conditions by means of an electric field or magnetic field is required. The cured objects having the specific molecular orientation have different strengths and thermal expansion coefficients according to the direction of molding. Under the stress-applying condition, like the solder heat resistance test after water absorption, stress is concentrated on specific portions of a package having low strength and eventually causes cracks in the package. The cured object prepared from the resin composition according to the present invention is only required to have a cured structure of substantially equivalent to that of the conventional thermosetting epoxy resin composition, and is not a cured object including a specific molecular orientation and having the deteriorating physical properties according to the direction. Another technique to further accelerate the orientation of molecules are proposed in which the epoxy compound having a liquid crystal properties-developing group is previously reacted with the compound having active hydrogen. This technique heightens the degree of polymerization of the resin composition, and accordingly increases the melt viscosity of the resin composition including inorganic fillers, which causes difficulties in the molding process. The present invention does not require any specific pre-reaction of the epoxy component with the epoxy curing component, and accordingly has no specific cured structure observed as a result of such pre-reaction. The conventional stilbene epoxy resin, having a high melting point and low solubility in an organic solvent, is hardly applied to laminated sheets, composite material, or coating material. JP-A-41 12 845 discloses hydroxystilbenes represented by the following formula: wherein R 2 and R 3 represent H, lower alkyl or halogen and R 4 and R 5 represent H, OH, lower alkoxy or halogen. SUMMARY OF THE INVENTION One object of the present invention is to provide a stilbene bisphenol as an intermediate of a stilbene epoxy resin having a relatively low melting point and favorable solubility in a solvent, as well as a method of manufacturing such a stilbene bisphenol. Another object of the present invention is to provide a stilbene epoxy resin having a low melting point and favorable solubility in a solvent as well as a method of manufacturing such a stilbene epoxy resin. Still another object of the present invention is to provide an epoxy resin composition, which is preferably used as a high performance encapsulating material with high reliability and is easily applicable to the conventional semiconductor encapsulating equipment and process without changing the molding conditions and time and the working properties of the conventional epoxy resin. The epoxy resin composition according to the invention has excellent working properties, low moisture absorption characteristics, and favorable heat resistance, and especially possesses high resistance against package cracks without any specific pre-reactions or curing conditions. DETAILED DESCRIPTION OF THE INVENTION The inventors have completed the present invention as a result of intensive studies. The present invention is directed to: [1] A stilbene bisphenol represented by the general formula (1), in which two different aryl groups are bound to a carbon-carbon double bond, wherein R 1 through R 8 independently represent acyclic or cyclic alkyl groups having 1 through 6 carbon atoms, hydrogen atom or halogen atoms, provided that each aryl group contains at least one acyclic or cyclic alkyl group having 1 through 6 carbon atoms. [2] A stilbene epoxy resin represented by the general formula (2), in which two different aryl groups are bound to a carbon-carbon double bond, wherein R 1 through R 8 independently represent acyclic or cyclic alkyl groups having 1 through 6 carbon atoms, hydrogen atom or halogen atoms, provided that each aryl group contains at least one acyclic or cyclic alkyl group having 1 through 6 carbon atoms. [3] A bisphenol mixture comprising a stilbene bisphenol represented by the general formula (1) in [1], and a stilbene bisphenol represented by the general formula (3) given below in which two identical aryl groups are bound to a carbon-carbon double bond, wherein R 9 through R 12 independently represent acyclic or cyclic alkyl groups having 1 through 6 carbon atoms, hydrogen atom or halogen atoms, provided that each aryl group contains at least one acyclic or cyclic alkyl group having 1 through 6 carbon atoms. [4] An epoxy resin mixture having a melting point of not higher than 150 °C, said epoxy resin mixture comprising a stilbene epoxy resin in [2], and a stilbene epoxy resin represented by the general formula (4) given below in which two identical aryl groups are bound to a carbon-carbon double bond, wherein R 9 through R 12 independently represent acyclic or cyclic alkyl groups having 1 through 6 carbon atoms, hydrogen atom or halogen atoms, provided that each aryl group contains at least one acyclic or cyclic alkyl group having 1 through 6 carbon atoms. [5] A stilbene bisphenol in accordance with [1], wherein R 1 represents t-butyl group, and R 5 through R 8 represent independently acyclic alkyl groups other than t-butyl group, cyclic alkyl groups, hydrogen atoms or halogen atoms in the general formula (1) given above. [6] An epoxy resin in accordance with [2], wherein R 1 represents a t-butyl group, and R 5 through R 8 represent acyclic alkyl groups other than t-butyl group, cyclic alkyl groups, hydrogen atoms or halogen atoms in the general formula (2) given above. [7] An epoxy resin mixture in accordance with [4], said epoxy resin mixture having a melt viscosity of not greater than 0.1 Pa·s (1 poise) at 150 °C. [8] A method of preparing a bisphenol mixture of [3], said method comprising the steps of: conducting a 1,1-bis(hydroxyphenyl)-2-chloroethane derivative, which is obtained by a reaction of two or more phenols with chloroacetaldehyde in the presence of an acid substance, to a dehydrochlorination reaction and a rearrangement reaction in the presence of a basic substance. [9] A method of preparing an epoxy resin mixture in accordance with [4], said method comprising the steps of: conducting a 1,1-bis(hydroxyphenyl)-2-chloroethane derivative, which is obtained by a reaction of two or more phenols with chloroacetaldehyde in the presence of an acid substance, to a dehydrochlorination reaction in the presence of a basic substance to yield a dihydroxystilbene derivative; and reacting said dihydroxystlibene derivative with an epihalohydrin in the presence of a basic substance. [10] A method of preparing an epoxy resin mixture in accordance with [4], said method comprising the steps of: making a 1,1-bis(hydroxyphenyl)-2-chloroethane derivative, which is obtained by a reaction of two or more phenols with chloroacetaldehyde in the presence of an acid substance, react with an epihalohydrin in the presence of a basic substance. [11] A method in accordance with either one of [9] and [10], wherein said phenols comprise two or more phenols selected among the group consisting of 2,6-xylenol, 2,4-xylenol, 3-methyl-6-t-butylphenol, and 2-methyl-6-t-butylphenol. [12] A method in accordance with [11], wherein said phenols comprise a mixture of 2,6-xylenol and 3-methyl-6-t-butylphenol. [13] An epoxy resin composition comprising: (A) a stilbene epoxy resin in accordance with either one of [2] and [4]; and (B) a phenolic epoxy curing agent. [14] An epoxy resin composition in accordance with [13], wherein said stilbene epoxy resin or epoxy resin mixture has a melting point of not higher than 150 °C. [15] An epoxy resin composition in accordance with either one of [13] and [14], wherein R 1 represents t-butyl group, and R 5 through R 8 independently represent acyclic alkyl groups other than t-butyl group or cyclic alkyl groups having 1 through 6 carbon atoms, hydrogen atoms, or halogen atoms in the general formula (2) given above. [16] An epoxy resin composition in accordance with [13], wherein said stilbene epoxy resin represented by the general formula (2) given above comprises an epoxy resin selected among glycidyl ether compounds of 3-t-butyl-2,4'-d ihydroxy-3',5',6-trimethylstilbene and 3-t-butyl-4,4'-dihyd roxy-3',5',6-trimethylstilbene, said stilbene epoxy resin represented by The general formula (4) given above comprising an epoxy resin selected among glycidyl ether compounds of 4,4'-dihydroxy-3,3',5,5'-tetramethylstilbene, 4,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene, 2,2'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene, and 2,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene. [17] An epoxy resin composition in accordance with [13], wherein the curing agent comprises a polyphenol resin having a melt viscosity of 0.15 Pa·s (1.5 poise) or less at 150 °C. [18] An epoxy resin composition in accordance with [17], wherein the polyphenol resin is represented by the general formula (5) wherein X represents single bond or methylene, Q represents phenylene or a divalent alicyclic moiety derived from dicyclopentadiene or limonene, and n represents an integer of 1 to 20. [19] An epoxy resin composition in accordance with [17], wherein the curing agent further comprises phenol novolak. [20] An epoxy resin composition furhter comprising (C) inorganic fillers, as well as said components (A) and (B) in accordance with any one of [13], [14], [15], [16], [17], [18] and [19]. [21] A resin-encapsulating semiconductor device manufactured by encapsulating a semiconductor element with an epoxy resin composition in accordance with [20]. Concrete examples of the substituents R 1 through R 12 in the stilbene bisphenols represented by Equations (1) and (3) and in the stilbene epoxy resins represented by Equations (2) and (4) in the present invention include methyl group, ethyl group, propyl group, butyl group, amyl group, hexyl group, and cyclohexyl group (including the respective isomers) as well as chlorine atom and bromine atom. Methyl group, ethyl group, propyl group, and butyl group are especially preferable, because of the low melt viscosity of products and availability of material. Concrete examples of the stilben bisphenol of the present invention represented by General Formula (1) given above and having two different aryl groups bound to a carbon-carbon double bond include 3-t-butyl-4,4'-dihydroxy-3'-methylstilbene, 3-t-butyl-4,4'-dihydroxy-5,3'-dimethylst ilbene, 3-t-butyl-4,4'-dihydroxy-3',6-dimethylstilbene, 3-t-butyl-4,4'-dihydroxy-5-ethyl-3'-methylstilbene, 3-t-butyl-4,4'-dihydroxy-3'-methyl-5-propylstilbene, 3-t-butyl-4,4'-dihydroxy-5-butyl-3'-methylstilbene, 3-t-butyl-4,4'-dihydroxy-5-amyl-3'-methylstilbene, 3-t-butyl-4,4'-dihydroxy-5-hexyl-3'-methylstilbene, 3-t-butyl-4,4'-dihydroxy-5-cyclohexyl-3'-methylstilbene, 3-t-butyl-4,4'-dihydroxy-3',5,5'-trimethylstilbene, 3-t-butyl-2,4'-dihydroxy-3',5',6-trimethylstilbene, 3-t-butyl-4,4'-dihydroxy-3',5',6-trimethylstilbene, 3-t-butyl-4,4'-dihydroxy-3',5-dimethyl-5'-propylstilbene, and 3-t-butyl-4,4'-dihydroxy-3' ,6-dimethyl-5'-propylstilbene. Especially preferable are 3-t-butyl-4,4'-dihydroxy-3',5,5'-trimethylstilbene, 3-t-butyl-2,4'-dihydroxy-3',5',6-trimethylstilbene, and 3-t-butyl-4,4'-dihydroxy-3',5',6-trimethylstilbene because of their easy syntheses, favorable performances, and less material cost. Glycidyl ether compounds of the above bisphenols are possible examples of the stilben epoxy resin of the present invention represented by General Formula (2) given above and having two different aryl groups bound to a carbon-carbon double bond. Concrete examples of the stilben bisphenol of the present invention represented by General Formula (3) given above and having two identical aryl groups bound to a carbon-carbon double bond include 4,4'-dihydroxy-3,3'-dimet hylstilbene, 3,3'-diethyl-4,4'-dihydroxystilbene, 4,4'-dihydroxy-3,3'-dipropylstilbene, 3,3'-diamyl-4,4'-dihy droxystilbene, 3,3'-dihexyl-4,4'-dihydroxystilbene, 3,3'-dicyclohexyl-4,4'-dihydroxystilbene, 2,2'-dihydroxy-3, 3',5,5'-tetramethylstilbene, 4,4'-dihydroxy-3,3',5,5'-tetra methylstilbene, 4,4'-dihydroxy-3,3'-di-t-butylstilbene, 4,4'-dihydroxy-3,3'-di-t-butyl-5,5'-dimethylstilbene, 4,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene, 2,2'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene, 2,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene, and 4,4'-dihydroxy-3,3',5,5'-tetra-t-butylstilbene. Especially preferable are 2,2'-dihydroxy-3,3',5,5'-tetramethylstilbene , 4,4'-dihydroxy-3,3',5,5'-tetramethylstilbene, 4,4'-dihydroxy-3,3'-di-t-butyl-5,5'-dimethylstilbene, 4,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene, 2,2'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene, and 2,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene because of their easy syntheses, favorable performances, and less material cost. Glycidyl ether compounds of the above bisphenols are possible examples of the stilben epoxy resin of the present invention represented by General Formula (4) given above and having two identical aryl groups bound to a carbon-carbon double bond. The intermediate of the stilbene bisphenol of the present invention, that is, 1,1-bis(hydroxyphenyl)-2-chloro ethane derivative, is obtained by the reaction of phenols with chloroacetaldehyde. Available examples of the t-butyl group-containing phenol include 3-methyl-6-t-butylphenol, 2-methyl-6-t-butylphenol, 2-t-butylphenol, 2-ethyl-6-t-butylphenol, 2-propyl-6-t-butylphenol, 2,6-di-t-butylphenol, 2-isobutyl-6-t-butylphenol, 2-amyl-6-t-butylphenol, ((2-amyl-6-t-butylphenol)), 2-hexyl-6-t-butylphenol, and 2-cyclohexyl-6-t-butylphenol. Especially preferable are 3-methyl-6-t-butylphenol and 2-methyl-6-t-butylphenol because of the favorable melting point of final products, availability of material, and less material cost. Possible examples of the phenol not containing a t-butyl group include cresol, xylenol, trimethylphenol, tetramethylphenol, methylethylphenol, methylpropylphenol, methylisobutylphenol, methylhexylphenol, and methylcyclohexylphenol (and their isomers). Especially preferable is xylenol because of its favorable balance of performances and material cost. Examples of the chloroacetaldehyde used in the present invention include chloroacetaldehyde, aqueous solutions of chloroacetaldehyde, acetals of chloroacetaldehyde, and trioxane-type trimers of chloroacetaldehyde. The amount of chloroacetaldehyde used is 0.8 through 1.4 moles, or preferably an equivalent mole, with respect to a total 1 mole of the phenols. The amount of chloroacetaldehyde less than this range causes the unreacted phenols to remain in the product, whereas the amount greater than this range often leads to polymerization of the product. The reaction of phenols with chloroacetaldehyde is generally carried out in the presence of an acidic substance. Possible examples of the acidic substance include: inorganic acids, such as fuming sulfuric acid, concentrated sulfuric acid, aqueous sulfuric acid, concentrated hydrochloric acid, hydrogen chloride gas, aqueous hydrochloric acid, and trifluorosulfonic acid; organic acids, such as p-toluenesulfonic acid, chloroacetic acid, trichloroacetic acid, and trifluoroacetic acid; heteropolyacids; and acidic ion exchange resins. Concentrated sulfuric acid is especially preferable, because it easily gives high-purity products. The amount of acidic substance used is 0.1 through 10 moles, or preferably 0.5 through 2 moles, with respect to 1 mole of chloroacetaldehyde. The amount of acidic substance less than this range results in the slow reaction, whereas the amount greater than this range is of no additional effect. Available solvents for the reaction include hydrocarbons like toluene and xylene, halogenated hydrocarbons like chlorobenzene, ethers like dioxane and tetrahydrofuran, alcohols like methanol and propanol, non-protic polar solvents like dimethyl sulfoxide, dimethylacetamide, and dimethylformamide, glycols like ethylene glycol and propylene glycol, and acidic solvents like acetic acid, wherein acetec acid is especially preferable. One or a mixture of these solvents may be used for the reaction. The amount of solvent used is 0.1 through 20 times, or preferably 0.5 through 10 times, the weight of phenols and chloroacetaldehyde. The amount of solvent less than this range makes precipitates deposited by the reaction interfere with smooth stirring, whreas the amount greater than this range lowers the yield and is economically disadvantageous. The acidic substance may be added dropwise to the phenols and chloroacetaldehyde previously dissolved in the solvent, or alternatively, chloroacetaldehyde may be added dropwise to the phenols and acidic substance in a reaction vessel. The time required for the dropwise addition is generally 0.5 hours through 10 hours. The reaction continues 3 through 24 hours after the dropwise addition. The reaction temperature is -30 through 60 °C or preferably -10 through 40 °C. The temperature lower than this range results in the slow reaction, whereas the temperature higher than this range significantly increases formation of impurities. After the reaction, the deposited precipitates are filtered off, washed with water, and dried under reduced pressure to yield 1,1-bis(hydroxyphenyl)-2-chloroet hane derivative as an intermediate. The intermediate is then subjected to a dehydrochlorination reaction and a rearrangement reaction. The 1,1-bis(hydroxyphenyl)-2-chloroethane derivative obtained is dissolved in a solvent and a basic substance, such as an aqueous solution of sodium hydroxide, is added dropwise to the solution to complete these reactions. Examples applicable for the solvent include hydrocarbons like toluene and xylene, halogenated hydrocarbons like chlorobenzene, ethers like dioxane and tetrahydrofuran, alcohols like methanol and propanol, non-protic polar solvents like dimethyl sulfoxide, dimethylacetamide, and dimethylformamide, glycols like ethylene glycol and propylene glycol, and acidic solvents like acetic acid, wherein alcohols like methanol and propanol are especially preferable. One or a mixture of these solvents may be used for these reactions. The amount of solvent used is 0.1 through 20 times, or preferably 0.5 through 10 times, the weight of 1,1-bis(hydroxyphenyl)-2-chloroethane derivative. The amount of solvent less than this range makes salts deposited by the reaction interfere with smooth stirring, whreas the amount greater than this range lowers the yield and is economically disadvantageous. The basic substance used for the reaction may be powder, pellets, or an aqueous solution of sodium hydroxide or potassium hydroxide, although an aqueous solution of sodium hydroxide is preferable because of its easy handling properties and low material cost. The amount of basic substance used is 1 through 5 moles, or preferably 1 through 2 moles, with respect to 1 mole of the 1,1-bis(hydroxyphenyl)-2-chloroethane derivative. The amount of basic substance less than this range causes unreacted material to remain in the product, whereas the amount greater than this range is of no additional effect. The basic substance may be added dropwise to the 1,1-bis(hydroxyphenyl)-2-chloroethane derivative previously dissolved in the solvent, or alternatively, powder, solution or slurry of the 1,1-bis(hydroxyphenyl)-2-chloroet hane derivative may be added dropwise to the basic substance ((phenols and acidic acid)) in a reaction vessel. The time required for the dropwise addition is generally 0.5 hours through 10 hours. The reaction continues 3 through 24 hours after the dropwise addition. The reaction temperature is -20 through 150 °C or preferably 20 through 100 °C. The temperature lower than this range results in the slow reaction, whereas the temperature higher than this range is of no additional effect. After the reaction, the reaction system is neutralized prior to removal of the solvent. Water is added to the reaction vessel after the removal of solvent, so as to allow crystallization of the reaction mixture. The precipitates obtained are filtered off, washed with water, and dried under reduced pressure to yield a bisphenol compound having a stilbene skeleton. A bisphenol mixture of the present invention may be prepared by mixing two or more bisphenol compounds separately synthesized with one another, or separately synthesizing intermediates obtained in the middle of the manufacturing process of bisphenol compounds and mixing the intermediates prior to completion of the residual reaction. The stilbene epoxy resin of the present invention is obtained through the known process of glycidyl etherification of the stilbene bisphenol given above. The known process makes the bisphenol react with an epihalohydrin in the presence of an alkali, such as sodium hydroxide. In order to give high-purity products, non-protic solvents and other solvents like dioxane are preferably used as disclosed in JAPANESE PATENT Laid-open No. S-60-31517. Concrete examples of the epihalohydrin used in the epoxidation reaction include epichlorohydrin and epibromohydrin, although epichlorohydrin is preferable because of its availability and low material cost. Preferable examples of the basic substance used in this reaction are, though not limited, alkali metal hydroxides like sodium hydroxide and potassium hydroxide. The preferable amount of basic substance used is an equivalent mole with respect to 1 mole of the phenolic hydroxyl group. The less amount of basic substance results in the remaining hydrolytic chlorine, while giving a less amount of gel as a by-product and being thus advantageous in the manufacturing process. The greater amount of basic substance, on the other hand, increases the amount of gel and is thus disadvantageous in the manufacturing process. Solvents applicable to the reaction include, though not limited, non-protic polar solvents like dimethyl sulfoxide, dimethyl sulfone, dimethylformamide, dimethylacetamide, and tetramethylurea, and ethers like dioxane and tetrahydrofuran. The preferable amount of the solvent used is 5 through 60 parts by weight with respect to 100 parts by weight of epihalohydrin. The amount of less than 5 parts by weight does not exert the effects of the present invention, whereas the greater amount allows the intermolecular reaction to proceed, thereby lowering the quality of products. The amount of epihalohydrin used is preferably 2.5 through 20 moles or more specifically 4 through 12 moles with respect to 1 mole of the phenolic hydroxyl group. The amount less than this range allows the intermolecular reaction to proceed, thereby lowering the quality of products, whereas the amount greater than this range lowers the yield and is disadvantageous from the induatrial viewpoint. The epoxidation reaction is implemented by dissolving or suspending the stilbene bisphenol derivative in a solution mixture of epihalohydrin and reaction solvent and further adding the basic subatance to the solution with stirring. The reaction is generally carried out under reduced pressure. The reaction solution is subjected to an azeotropic process while the reaction temperature is kept in a range of 30 to 80 °C. A volatile matter is condensed, and the condensed solution thus obtained undergoes a process of oil-water separation, where the oil substance is returned to the reaction system while water is removed. The basic substance in limited amounts is added separately or continuously over 2 through 10 hours for the homogeneous reaction. Simultaneously supply of the whole amount of basic substance causes the reaction to proceed locally and unfavorably gives a gel. After completion of the reaction, unreacted epihalohydrin and solvent is removed by distillation, and the residue is dissolved in a solvent separable from water, for example, methyl isobutyl ketone, for removal of insoluble inorganic salts. The solution is further washed with water for removal of an inorganic component and the remaining polar solvent, and distilled for removal of the remaining solvent to yield a final epoxy product. The stilbene epoxy resin of the present invention may alternatively be obtained through simultaneous rearrangement reaction and epoxidation reaction of the 1,1-bis(hydroxyphenyl)-2-chloroethane derivative. In this process, the preferable amount of the basic substance used is (an equivalent mole with respect to 1 mole of the phenolic hydroxyl group) + (an equivalent mole with respect to 1 mole of the hydrolytic chlorine). Since the 1,1-bis(hydroxyphenyl)-2-chloroethane derivative has two hydroxyl groups and one hydrolytic chlorine atom per molecule, three moles of the basic substance are preferably used with respect to 1 mole of the 1,1-bis(hydroxyphenyl)-2 -chloroethane derivative. The less amount of basic substance results in the remaining hydrolytic chlorine, while giving a less amount of gel as a by-product and being thus advantageous in the manufacturing process. The greater amount of basic substance, on the other hand, increases the amount of gel and is thus disadvantageous in the manufacturing process. The essential conditions of epoxidation reaction are identical with those specified above. A mixture of the epoxy resin represented by General Formula (2) and that represented by General Formula (4) according to the present invention may be prepared by mixing separately synthesized epoxy resins with one another, or separately synthesizing intermediates obtained in the middle of the epoxidation process and mixing the intermediates prior to completion of the residual epoxidation reaction. In the process of synthesizing the stilbene phenol represented by General Formula (1) as a material of epoxy resin, the stilbene phenol represented by General Formula (3) is formed with the stilbene phenol of General Formula (1). For example, a mixture of stilbene phenols having three different basic skeletons X-CH=CH-X, X-CH=CH-Y, and Y-CH=CH-Y are synthesized from two different phenols X and Y used as starting materials. The stilbene epoxy resin represented by General Formula (2) and having two different aryl groups bound to a carbon-carbon double bond is derived from the stilbene phenol of X-CH=CH-Y, where the benzene rings linked with the carbon-carbon double bond have different substituents at different positions. The epoxy resin according to the present invention is required to include the epoxy resin represented by General Formula (2). The epoxy resin containing only that represented by General Formula (2) is obtained by isolating X-CH=CH-Y from the mixture of stilbene phenols and glycidyl etherifying the stilbene phenol X-CH=CH-Y. An epoxy resin having a sufficiently low melting point and improved working properties can not be obtained by simply mixing epoxy resins derived from the stilbene phenols of X-CH=CH-X and Y-CH=CH-Y. Combination of three or more phenols as starting materials gives a similar mixture of stilbene phenols. For example, three different phenols X, Y, and Z give a mixture of stilbene phenols having different basic skeletons of X-CH=CH-X, X-CH=CH-Y, X-CH=CH-Z, Y-CH=CH-Y, Y-CH=CH-Z, and Z-CH=CH-Z. The epoxy resin according to the present invention is required to include at least one of the epoxy resins derived from the stilbene phenols of X-CH=CH-Y, X-CH=CH-Z, and Y-CH=CH-Z. Staring materials of four or more phenols give similar mixtures. The epoxy resin according to the present invention includes only one or a plurality of epoxy resins represented by General Formula (2), or alternatively includes one or a plurality of epoxy resins represented by General Formula (4) in addition to one or a plurality of epoxy resins of General Formual (2). In a mixture of (A) one or a plurality of epoxy resins of General Formula (2) and (B) one or a plurality of epoxy resins of General Formula (4), the amount of the component (A) is generally not less than 1% by weight, or preferably not less than 10% by weight, with respect to the total weight of the components (A) and (B). The less content of the component (A) increases the melting point of the resulting epoxy resin and deteriorates the working properties in the mixing process with another component. The content of the component (A) is increased to give epoxy resins required to have a lower melting point and decreased to give epoxy resins required to have a higher melting point. In the process of the present invention, the component (A) and the component (B) may be synthesized separately and then mixed with each other. The epoxy resin composition of the present invention may include the above stilbene epoxy resin together with another known epoxy resin. Known epoxy resins applicable for the epoxy resin composition include: glycidyl ether compounds derived from divalent phenols, such as bisphenol A, bisphenol F, hydroquinone, resorcinol, dihydroxynaphthalene, bis(4-hydroxyphenyl)menthane, bis(4-hydroxyphenyl)dicyclopentane, 4,4'-dihydroxybenzophenone, bis(4-hydroxyphenyl) ether, bis(4-hydroxy-3-methylphenyl) ether, bis(3,5-dimethyl-4-hyd roxyphenyl) ether, bis(4-hydroxyphenyl) sulfide, bis(4-hydroxy-3-methylphenyl) sulfide, bis(3,5-dimethyl-4-h ydroxyphenyl) sulfide, bis(4-hydroxyphenyl) sulfone, bis(4-hydroxy-3-methylphenyl) sulfone, bis(3,5-dimethyl-4-h ydroxyphenyl) sulfone, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, 1,1-bis(3,5-d imethyl-4-hydroxyphenyl)cyclohexane, 4,4'-dihydroxybiphenyl, 4,4'-dihydroxy-3,3',5,5'-tetramethy lbiphenyl, bis(hydroxynaphthyl)methane, 1,1'-binaphthol, and 1,1'-bis(3-t-butyl-6-methyl-4-hydroxyphenyl)butane; diglycidyl ether compounds derived from halogenated bisphenols, such as tetrabromobisphenol A; polyphenol and polynaphthol novolak resins obtained as reaction products of phenols, such as phenol, o-cresol, and catechol, or naphthols, such as hydroxynaphthalene and dihydroxynaphthalene, with aldehydes, such as formaldehyde; trityl skeleton-containing polyphenols obtained by condensation of phenols, such as phenol, cresol, and methyl-t-butylphenol, and aromatic aldehydes, such as hydroxybenzaldehyde; trityl skeleton-containing polyphenol novolaks obtained as reaction products of trityl skeleton-containing polyphenols with formaldehyde or the like; polyaralkylphenol resins and polyaralkylnaththol resins obtained as reaction products of phenols, such as phenol, o-cresol, and catechol, or naphthols, such as hydroxynaphthalene and dihydroxynaphthalene, with xylylene dichloride, bis(hydroxymethyl)benzene, or the like; alicyclic hydrocarbon-containing polyphenol resins and polynaththol resins obtained as reaction products of phenols, such as phenol, o-cresol, and catechol, or naphthols, such as hydroxynaphthalene and dihydroxynaphthalene, with unsaturated alicyclic hydrocarbons, such as dicyclopentadiene and limonene; alicyclic hydrocarbon-containing polyphenol novolak resins and polynaththol novolak resins obtained as reaction products of alicyclic hydrocarbon-containing polyphenol resins or polynaththol resins with formaldehyde or the like; glycidyl ether compounds of polyvalent phenols and polyvalent naththols obtained by condensation reaction of phenols or naththols with aromatic carbonyl compounds; glycidyl ether compounds derived from trivalent or higher multivalent phenols including as a fundamental skeleton fluoroglycine, tris(4-hydroxyphenyl)methane, 1,1,2,2,-tetra kis(4-hydroxyphenyl)ethane, 1,3-bis[bis(4-hydroxyphenyl)met hyl]benzene, 1,4-bis[bis(4-hydroxyphenyl)methyl]benzene, or the like and cyclic phenols, such as calixarene. The known epoxy resins also include amine epoxy resins derived from p-aminophenol, m-aminophenol, 4-amino-m-cresol, 6-amino-m-cresol, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benz ene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 2,2-bis(4-aminophenoxyphenyl)propane, p-phenylenediaminde, m-phenylenediaminde, 2,4-toluenediaminde, 2,6-toluenediamine, p-xylylenediamine, m-xylylenediamine, 1,4-cyclohexanebis(methylamine), 1,3-cyclohexanebis(methylamine), and N,N-diglycidylaniline; glycidyl ester compounds derived from aromatic carboxilic acids, such as p-oxybenzoic acid, m-oxybenzoic acid, terephthalic acid, and isophthalic acid; hydantoin epoxy compounds derived from 5,5-dimethylhydantoin or the like; alicyclic epoxy resins, such as 2,2-bis(3,4-epoxycyclohexyl )propane, 2,2-bis[4-(2,3-epoxypropyl)cyclohexyl]propane, vinylcyclohexene dioxide, 3,4-epoxycyclohexylmethyl-3,4-epo xycyclohexane carboxylate; and aliphatic epoxy resins obtained by oxidation of the double bond included in unsaturated hydrocarbons, such as polybutadiene. One or a mixture of these epoxy resins may be included in the epoxy resin composition. Examples of the phenolic epoxy curing agent applicable to the present invention include: polyphenol and polynaphthol novolak resins obtained as reaction products of phenols, such as phenol, o-cresol, and catechol, or naphthols, such as hydroxynaphthalene and dihydroxynaphthalene, with aldehydes, such as formaldehyde; trityl skeleton-containing polyphenols obtained by condensation of phenols, such as phenol, cresol, and methyl-t-butylphenol, and aromatic aldehydes, such as hydroxybenzaldehyde; trityl skeleton-containing polyphenol novolaks obtained as reaction products of trityl skeleton-containing polyphenols with formaldehyde or the like; polyaralkylphenol resins and polyaralkylnaththol resins obtained as reaction products of phenols, such as phenol, o-cresol, and catechol, or naphthols, such as hydroxynaphthalene and dihydroxynaphthalene, with xylylene dichloride, bis(hydroxymethyl)benzene, or the like; alicyclic hydrocarbon-containing polyphenol resins and polynaththol resins obtained as reaction products of phenols, such as phenol, o-cresol, and catechol, or naphthols, such as hydroxynaphthalene and dihydroxynaphthalene, with unsaturated alicyclic hydrocarbons, such as dicyclopentadiene and limonene; alicyclic hydrocarbon-containing polyphenol novolak resins and polynaththol novolak resins obtained as reaction products of alicyclic hydrocarbon-containing polyphenol resins or polynaththol resins with formaldehyde or the like; trivalent or higher multivalent phenols including as a fundamental skeleton fluoroglycine, tris(4-hydroxyphenyl)methane, 1,1,2,2,-tetrakis(4-hydroxyph enyl)ethane, 1,3-bis[bis(4-hydroxyphenyl)methyl]benzene, 1,4-bis[bis(4-hydroxyphenyl)methyl]benzene, or the like; and cyclic phenols, such as calixarene. Preferable are phenol novolak resins, naphthol novolak resins, phenol aralkyl resins, naphthol aralkyl resins, trityl skeleton-containing polyphenols, trityl skeleton-containing polyphenol novolaks, alicyclic hydrocarbon-containing polyphenol resins, and alicyclic hydrocarbon-containing polynaththol resins because of their favorable curing properties and moisture resistance. One or a mixture of these compounds may be used for the epoxy curing agent. Especially preferable is a polyphenol resin having a melt viscosity of 0.15 Pa·s (1.5 Poise) less at 150 °C. The polyphenol resin is exemplified by the general formula (5) wherein X represents single bond or methylene, Q represents phenylene or a divalent alicyclic moiety derived from dicyclopentadiene or limonene, and n represents an integer of 1 to 20, preferably 1 to 10. Examples of the divalent alicyclic moiety derived from dicyclopentadiene or limonene are specifically shown as below. Divalent bisphenols may further be added according to the requirements. Examples of the applicable bisphenol include: divalent phenols, such as bisphenol A, bisphenol F, hydroquinone, resorcinol, dihydroxynaphthalene, bis(4-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)butane, bis(4-hydroxyphenyl)pentane, bis(4-hydroxyphenyl)hexane, 1,3,3-trimethyl-1-m-hydroxyphenylindan-5-or-7-ol, bis(4-hydroxyphenyl)dicyclopentane, 4,4'-dihydroxybenzophenone, bis(4-hydroxyphenyl) ether, bis(4-hydroxy-3-methylphenyl) ether, bis(3,5-dimethyl-4-hyd roxyphenyl) ether, bis(4-hydroxyphenyl) sulfide, bis(4-hydroxy-3-methylphenyl) sulfide, bis(3,5-dimethyl-4-h ydroxyphenyl) sulfide, bis(4-hydroxyphenyl) sulfone, bis(4-hydroxy-3-methylphenyl) sulfone, bis(3,5-dimethyl-4-h ydroxyphenyl) sulfone, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, 1,1-bis(3,5-d imethyl-4-hydroxyphenyl)cyclohexane, 4,4'-dihydroxybiphenyi, 4,4'-dihydroxy-3,3',5,5'-tetramethy lbiphenyl, bis(hydroxynaphthyl)methane, 1,1'-binaphthol, and 1,1'-bis(3-t-butyl-6-methyl-4-hydroxyphenyl)butane; and halogenated bisphenols, such as tetrabromobisphenol A. Other than the above phenols, the following compounds may also be added according to the requirements: polycarboxylic acids, such as maleic acid, phthalic acid, nadic acid, methyl-tetrahydrophthalic acid, and methylnadic acid, and anhydrides thereof; polyamines, such as diaminodiphenylmethane, diaminodiphenyl sulfone, diaminodiphenyl ether, phenylenediamine, diaminodicyclohexylmethane, xylylenediamine, toluenediamine, diaminocyclohexane, dichloro-diaminodiphenylmehtane (including their isomers), ethylenediamine, and hexamethylenediamine; and active hydrogen-containing compounds capable of reacting with the epoxy group, such as dicyandiamide and tetramethylguanidine. The content of the epoxy curing agent is preferably 0.7 through 1.2 times the weight of the epoxy resin, or more specifically an equivalent weight to that of the epoxy resin. An extreme shift from the equivalent composition results in lowering the moisture resistance and curing properties. In the process of curing the epoxy resin composition of the present invention, a known curing accelerator may be added. Examples of the applicable curing accelerator, though not limited, include: organophosphine compounds, such as triphenylphosphine, tri-4-methylphenylphosphine, tri-4-methoxyphenylphosphine, tributylphosphine, trioctylphosphine, and tri-2-cyanoethylphosphine, and their tetraphenylborates; tertiary amines, such as tributylamine, triethylamine, 1,8-diazabicyclo(5,4,0)-7-undecene, and triamylamine; quaternary ammonium salts, such as benzyltrimethylammonium chloride, benzyltrimethylammonium hydroxide, and triethylammonium tetraphenylborate; and imidazoles. Because of their favorable moisture resistance and curing properties, organophosphine compounds, 1,8-diazabicyclo(5,4,0)-7-undecene, and imidazoles, especially triphenylphosphine, are preferable. The inorganic fillers added as the component (C) to the epoxy resin composition of the present invention may be silica, alumina, titanium white, aluminum hydroxide, talc, clay, or glass fibers, where silica and alumina are especially preferable examples. The inorganic fillers used may be a bulky mixture of different shapes (spherical and ground) and sizes. The content of inorganic fillers is required to be 25 through 95% by weight with respect to the total weight of the resin composition; preferably 70 through 95% by weight and more preferably 80 through 95% by weight. The content of inorganic fillers less than 80% by weight results in poor moisture resistance, whereas that greater than 95% by weight deteriorates the molding properties. The spherical powder may be approximately spheres in shape possessing no acute vertices and having the aspect ratio of 1.0 through 1.2. Preferably used is spherical powder having the spherical degree similar to that of commercially available silica powder prepared by flame spraying or sol-gel method, where that substantially close to the true sphere is especially preferable. When the standard spherical process is not applicable, spherical powder may be prepared by making finely ground particles mixed with a binder spherical by a mechanochemical approach. The ground particles may be polyhedrons or bodies of any other irregular shapes possessing vertices. Ground particles of non-crystalline or crystalline quartz obtained by grinding synthetic or natural quartz block are preferable; for example, ground molten silica. Although any spherical powder is applicable to the present invention, a preferable example including three components x, y, and z is described here. The x, y, and z components respectively have the average particle diameter of not less than 0.1 µm and not greater than 1.5 µm, not less than 2 µm and not greater than 15 µm, and not less than 20 µm and not greater than 70 µm, or more preferably having the average particle diameter of not less than 0.1 µm and not greater than 1.0 µm, not less than 2 µm and not greater than 10 µm, and not less than 20 µm and not greater than 50 µm. Powder having the average particle diameter of less than 0.1 µm causes aggregation of particles, which interferes with homogeneous dispersion into the resin composition and may damage the flow properties. Powder having the average particle diameter of greater than 70 µm, on the other hand, can not be charged easily into fine portions of semiconductor elements. The x, y, and z components having the average particle diameter out of the respective ranges deteriorate the flow properties of the resin composition. The spherical powder used in the present invention preferably has a narrower variance of particle diameter, or more specifically a single variance. Classification process is thus preferable to select particles having substantially uniform particle diameters for all the x, y, and z components. The average particle diameter here is defined as the value of particled diameter under the condition of 50% weight cumulation when the distribution of particle diameter is measured with a particle size distribution measuring apparatus, for example, a laser scattering granulometer. The volume ratios of the spherical powdery components x, y, and z with respect to the calculated total volume of the x, y, and z components are preferably not less than 10% by volume and not greater than 24% by volume, not less than 0.1% by volume and not greater than 66% by volume, and not less than 24% by volume and not greater than 76% by volume, more preferably not less than 10% by volume and not greater than 24% by volume, not less than 0.1% by volume and not greater than 36% by volume, and not less than 57% by volume and not greater than 76% by volume, or most preferably not less than 10% by volume and not greater than 20% by volume, not less than 4% by volume and not greater than 30% by volume, and not less than 60% by volume and not greater than 76% by volume. The volume ratios out of these ranges lower the flow properties of the resulting resin composition. The values of '% by volume' in the present invention are calculated using the quatients obtained by dividing the respective weights of the x, y, and z components by their true specific gravities as volumes of the respective components. In general, the apparent volume of particles having a certain particle diameter distribution is varied by the filling conditions of particles in a measuring vessel and before and after the process of mixing different sets of particles. In the description above, the apparent volume is thus not used for the calculation of '% by volume' of each component or set of particles. The ground particles (component m) used in the present invention have the average particle diameter of not less than 1 µm and not greater than 70 µm, or preferably not less than 1 µm and not greater than 30 µm. The preferable ratio of the weight of the ground particles (component m) to the total weight of the component of spherical powder and the component m of ground particles is not less than 1% by weight and not greater than 30% by weight. The content less than this range does not have sufficient effects of reducing fins and flashes (thin resin films formed by the leaked resin substance) formed according to the properties of resin and the shapes of the encapsulating device and molding device used. The content exceeding this range, on the other hand, lowers the flow properties of the resulting resin composition. It is preferable that the fillers used in the present invention are sufficiently mixed and blended in advance. According to a concrete procedure, the fillers are blended with a device utilizing rotors or the air, such as a mixer or a Ko-kneader, or a device for vibrating, shaking, or rotating a vessel with the fillers set therein. In order to determine whether the fillers are sufficiently kneaded, particle size distributions are measured for samples from different positions and compared with one another for identification. The fillers may be pre-treated with a coupling agent or resin according to the requirements. One applicable method of pre-treatment mixes a coupling agent or resin with the fillers in a solvent and subsequently removes the solvent. Another method directly mixes a coupling agent or resin with the fillers by means of a blender. Natural wax, synthetic wax, higher fatty acids and their metal salts, parting agents like paraffin, coloring agents like carbon black, and finishing agents like silane coupling agents may further be added to the composition of the present invention. Flame-retardants like antimony trioxide, phosphorus compounds, and brominated epoxy resins may also be added; brominated epoxy resins are especially preferable for the preferable flame-retarding effects. A variety of non-reacted or reacted elastomers may be added in order to lower the stress. Concrete examples of the non-reacted or reacted elastomers include polybutadiene, butadiene-acrylonitrile copolymer, silicone rubber, and silicone oil. The resin composition according to the present invention may be used for encapsulating semi-conductors or other electronic parts. Resin-encapsulated semiconductor devices are prepared by a known molding process, such as transfer molding, compression molding, or injection molding. [Examples] Examples of the present invention are given below, although the invention is not restricted in any sense to these examples. In the description below, the epoxy equivalent weight is defined by the molecular weight of epoxy resin per epoxy group. The quantity of hydrolytic chlorine expressed by ppm was measured by dissolving the epoxy resin in dioxane, adding an alcohol solution of potassium hydroxide to the resin solution, heating the resin solution for 30 minutes under reflux, and measuring the quantity of chlorine ions released from the resin solution by back titration with an aqueous solution of silver nitrate. Properties of the kneaded substances and cured objects were evaluated according to the following methods. Working properties: The working properties in the mixing process of kneading the resin component, inorganic fillers, and other additives were evaluated using Reference 3 as a standard. Open circles (o) represent equivalent working properties to those of Reference 3 and crosses (x) represent poor working properties having difficulty in preparation of homogeneous material. Barcol hardness: The Barcol hardness was measured under the condition of 175 °C/90 sec with a model-935 hardness tester according to ASTM D-648. Glass transition temperature: The glass transition temperature was measured with a heat mechanical analyzer (SHIMADZU DT-30). Bending strength, Bending modulus: The bending strength and the bending modulus were measured with a tensile machine (SHIMADZU IS-10T) according to JIS K-6911. Water absorption: The variation in weight was measured under the condition of 85 °C/85%RH with a constant-temperature, constant-humidity bath (Advantec TOYO AGX-326). Spiral flow: The spiral flow was measured under the condition of 175 °C/70 kg/cm 2 in conformity with EMMI-1-66. Solder cracking: Simulated ICs (52-pin QFD packaging: thickness in packaging = 2.05 mm) were exposed to the moisture under the condition of 85 °C/85%RH and then soaked in a solder bath of 240 °C for 30 seconds. The number of ICs having cracks were measured. Ten samples were tested for each resin. Reference 1 (1) Synthesis of 1,1-bis(hydroxyphenyl)-2-chloroethane derivative - 1 In a 2-liter four-necked flask with a thermometer, a stirrer, and a condenser, 244.4 g (2.0 mol) of 2,6-xylenol (hereinafter referred to as 26XY) and 193.8 g (1.0 mol) of a 40.5% aqueous solution of chloroacetaldehyde were added to and dissolved in 376 g of acetic acid with stirring, and the reaction solution was then cooled to 5 °C. A solution prepared by mixing 122 g (1.2 mol) of concentrated sulfuric acid with 84 g of acetic acid was added dropwise to the reaction mixture at 5 °C over 3 hours. The reaction mixture was then maintained at the constant temperature of 25 °C for 6 hours, and stirred overnight at ambient temperature. The reaction mixture was again cooled to 5 °C, and deposited precipitates were filtered off. The precipitates thus obtained were washed with 500 g of water six times and dried in vacuo at 40 °C for 8 hours to give 264 g of colorless precipitates (yield: 86.6%) (hereinafter referred to as XYCE). Gel permeation chromatography (hereinafter referred to as GPC: detected with the ultraviolet ray of 254 nm) showed that the purity of the product was 98.3%, while infrared absorption spectrum gave a broad absorption band due to the hydroxyl group in the vicinity of 3500cm -1 . A fragment of the molecular weight=304 was observed by mass spectrometry. (2) Synthesis of stilbene bisphenol - 1 In a 2-liter ((liter)) four-necked flask with a thermometer, a stirrer, and a condenser, 225.6 g of XYCE obtained in the above process (1) was dissolved with stirring in 451.2 g of methanol under nitrogen atmosphere. After 91.9 g of a 48.3% aqueous solution of sodium hydroxide was added dropwise to the solution over 1 hour at the internal temperature of 30 °C, the reaction mixture was heated and reacted for 3 hours under reflux of methanol. After the reaction, complete disappearance of the material XYCE was confirmed by high performance liquid chromatography (hereinafter referred to as LC). The reaction mixture was cooled to 60 °C and neutralized with 37.5 g of concentrated hydrochloric acid. After removal of methanol, 1000g of warm water was added to the reaction mixture, and precipitates thus deposited were filtered off. The precipitates obtained were washed with water and dried in vacuo at 80 °C for 8 hours to give 192 g of yellow precipitates (yield: 96.7%) (hereinafter referred to as XYSB). GPC showed that the purity of the product was 98.1%, while infrared absorption spectrum gave a broad absorption band due to the hydroxyl group in the vicinity of 3400cm -1 . A fragment of the molecular weight=268 was observed by mass spectrometry. (3) Synthesis of epoxy resin - 1 In a reaction vessel with a thermometer, a stirrer, a dropping funnel, and a columned condenser, 100 g of the material phenol (XYSB) obtained in the above process (2) was dissolved in 485.6 g of epichlorohydrin and 242.8 g of 1,4-dioxane. While the reaction system was kept at 140 torr, 61.71 g of a 48.3% aqueous solution of sodium hydroxide was continuously added dropwise over 5 hours at the temperature of 62 °C. The reaction proceeded at the fixed temperature of 62 °C, while the azeotropic mixture of epichlorohydrin and water was cooled and liquefied and the organic phase was returned to the reaction system.After completion of the reaction, unreacted epichlorohydrin and 1,4-dioxane were removed by evaporation under reduced pressure. The glycidyl ether obtained and by-product salts were dissolved in 800 g of methyl isobutyl ketone and washed with water for removal of the by-product salts. Subsequent removal of methyl isobutyl ketone at 160 °C under the reduced pressure of 1.33 kPa (10 torr) gave 122.2 g of final product (yield: 86.2%) (hereinafter referred to as XYCC-E).The product had the purity of 93.0% measured by GPC (detected with a differential refractometer), the melting point of 151 °C, and the epoxy equivalent weight of 198 g/eq. Infrared spectroscopy showed that the absorption due to the phenolic hydroxyl group disappeared and that the product had absorptions of 1240cm -1 and 915cm -1 due to the epoxy group. Reference 2 (1) Synthesis of 1,1-bis(hydroxyphenyl)-2-chloroethane derivative - 2 Synthesis was carried out in the same manner as Reference 1(1), except that 328.5 g (2.0 mol) of 3-methyl-6-t-butylphenol (hereinafter referred to as 3M6B) was used in place of 244.4 g (2.0 mol) of 26XY, to gave 317 g of pale purple precipitates (yield: 81.5%) (hereinafter referred to as XMCE-100). GPC (detected with the ultraviolet ray of 254 nm) showed that the purity of the product was 87.7%, while infrared absorption spectrum gave a broad absorption band due to the hydroxyl group in the vicinity of 3500cm -1 . A fragment of the molecular weight=389 was observed by mass spectrometry. (2) Synthesis of stilbene bisphenol - 2 Synthesis was carried out in the same manner as Reference 1(2), except that XMCE-100 obtained in the above process (1) of Reference 2 was used in place of XYCE, to gave 134 g of pale yellow precipitates (yield: 94.8%) (hereinafter referred to as XMSB-100). GPC showed that the purity of the product was 93.5%, while infrared absorption spectrum gave a broad absorption band due to the hydroxyl group in the vicinity of 3100cm -1 . A fragment of the molecular weight=352 was observed by mass spectrometry. (3) Synthesis of epoxy resin - 2 The epoxidation was carried out in the same manner as Reference 1(3), except that XMSB-100 obtained in the above process (2) was used in place of XYSB, to gave 54.7 g of final product (yield: 36.2%) (hereinafter referred to as XMCC-100E). The product had the purity of 95.2% measured by GPC (detected with a differential refractometer), the melting point of 220 through 224 °C, and the epoxy equivalent weight of 230 g/eq. Infrared spectroscopy showed that the absorption due to the phenolic hydroxyl group disappeared and that the product had absorptions of 1230cm -1 and 920cm -1 due to the epoxy group. Example 1 (1) Synthesis of 1,1-bis(hydroxyphenyl)-2-chloroet hane derivative - 3 Synthesis was carried out in the same manner as Reference 1(1), except that 195.5 g (1.6 mol) of 26XY and 65.7 g (0.4 mol) of 3M6B were used in place of 244.4 g (2.0 mol) of 26XY, to gave 271 g of pale purple precipitates (yield: 84.1%) (hereinafter referred to as XMCE-20). GPC (detected with the ultraviolet ray of 254 nm) showed that the purity of the product was 97.7%, while infrared absorption spectrum gave broad absorption bands due to the hydroxyl group in the vicinity of 3450cm -1 and 3550cm -1 . Fragments of the molecular weight=346 and 304 were observed by mass spectrometry. XMCE-100 of Reference 2(1) ((Reference 4)) was not observed by LC analysis. (2) Synthesis of stilbene bisphenol - 3 Synthesis was carried out in the same manner as Reference 1(2), except that 144.8 g of XMCE-20 obtained in the above process (1) of Example 1 was used in place of XYCE, to gave 124 g of yellow precipitates (yield: 96.6%) (hereinafter referred to as XMSB-20). GPC (detected with the ultraviolet ray of 254 nm) showed that the purity of the product was 97.1%, while infrared absorption spectrum gave a broad absorption band due to the hydroxyl group in the vicinity of 3400cm -1 . Fragments of the molecular weight=310 and 268 were observed by mass spectrometry. XMSB-100 of Reference 2(2) ((Reference 5)) was not observed by LC analysis. (3) Synthesis of epoxy resin - 3 The epoxidation was carried out in the same manner as Reference 1(3), except that 99.7 g of XMSB-20 obtained in the above process (2) was used in place of XYSB, to gave 131 g of final product (yield: 94%) (hereinafter referred to as XMCC-20E).GPC (detected with a differential refractometer) showed that the purity of the product was 93.6% and the rate of the stilbene epoxy compound including the 26XY residue and the 3M6B residue ((including 26XY and 3M6B)) in its molecular structure was 39.6%. The product had the melting point of 110 through 130 °C, and the epoxy equivalent weight of 208 g/eq. Infrared spectroscopy showed that the absorption due to the phenolic hydroxyl group disappeared and that the product had absorptions of 1240cm -1 and 920cm -1 due to the epoxy group. Example 2 (1) Synthesis of 1,1-bis(hydroxyphenyl)-2-chloroethane derivative - 4 Synthesis was carried out in the same manner as Reference 1(1), except that 171.1 g (1.4 mol) of 26XY and 98.6 g (0.6 mol) of 3M6B were used in place of 244.4 g (2.0 mol) of 26XY, to gave 253 g of pale purple precipitates (yield: 76.7%) (hereinafter referred to as XMCE-30). GPC (detected with the ultraviolet ray of 254 nm) showed that the purity of the product was 96.0%, while infrared absorption spectrum gave broad absorption bands due to the hydroxyl group in the vicinity of 3450cm -1 and 3550cm -1 . Fragments of the molecular weight=346 and 304 were observed by mass spectrometry. XMCE-100 of Reference 2(1) ((Reference 4)) was not observed by LC analysis. (2) synthesis of stilbene bisphenol - 4 Synthesis was carried out in the same manner as Reference 1(2), except that 122.1 g of XMCE-30 obtained in the above process (1) was used in place of XYCE, to gave 108 g of yellow precipitates (yield: 99.4%) (hereinafter referred to as XMSB-30). GPC (detected with the ultraviolet ray of 254 nm) showed that the purity of the product was 93.3%, while infrared absorption spectrum gave a broad absorption band due to the hydroxyl group in the vicinity of 3400cm -1 . Fragments of the molecular weight=310 and 268 were observed by mass spectrometry. XMSB-100 of Reference 2(2) was not observed by LC analysis. (3) Synthesis of epoxy resin - 4 The epoxidation was carried out in the same manner as Reference 1(3), except that 95.4 g of XMSB-30 obtained in the above process (2) was used in place of XYSB, to gave 118 g of final product (yield: 89.5%) (hereinafter referred to as XMCC-30E).GPC (detected with a differential refractometer) showed that the purity of the product was 86.6% and the rate of the stilbene epoxy compound including the 26XY residue and the 3M6B residue ((including 26XY and 3M6B)) in its molecular structure was 53.2%. The product was semisolid at ambient temperature and had the epoxy equivalent weight of 200 g/eq. The melt viscosity was 0.016 Pa·s (0.16 poise) at 150 °C. Infrared spectroscopy showed that the absorption due to the phenolic hydroxyl group disappeared and that the product had absorptions of 1260cm -1 and 910cm -1 due to the epoxy group. Example 3 (1) Synthesis of 1,1-bis(hydroxyphenyl)-2-chloroethane derivative - 5 Synthesis was carried out in the same manner as Reference 1(1), except that 122.2 g (1.0 mol) of 26XY and 164.3 g (1.0 mol) of 3M6B were used in place of 244.4 g (2.0 mol) of 26XY, to gave 321 g of colorless precipitates (yield: 92.5%) (hereinafter referred to as XMCE-50). GPC (detected with the ultraviolet ray of 254 nm) showed that the purity of the product was 90.7%, while infrared absorption spectrum gave broad absorption bands due to the hydroxyl group in the vicinity of 3450cm -1 and 3550cm -1 . Fragments of the molecular weight=346 and 304 and a faint fragment of the molecular weight=389 were observed by mass spectrometry. (2) Synthesis of stilbene bisphenol - 5 Synthesis was carried out in the same manner as Reference 1(2), except that 114.7 g of XMCE-50 obtained in the above process (1) was used in place of XYCE, to gave 98.5 g of pale brown precipitates (yield: 95.8%) (hereinafter referred to as XMSB-50). GPC (detected with the ultraviolet ray of 254 nm) showed that the purity of the product was 96.5% and the rate of the stilbene compound including the 26XY residue and the 3M6B residue ((including 26XY and 3M6B)) in its molecular structure was 86.4%. Infrared absorption spectrum gave a broad absorption band due to the hydroxyl group in the vicinity of 3400cm -1 . Fragments of the molecular weight=310 and 268 and a faint fragment of the molecular weight=352 were observed by mass spectrometry. (3) Purification of stilbene bisphenol XMSB-50 obtained in the above process (2) of Example 3 was recrystallized from toluene. Precipitates thus obtained were washed with cyclohexane and dried under reduced pressure to yield fine brown precipitates. The purity measured by high performance liquid chromatography (hereinafter referred to as LC) was 99.1%, and the retention time of the fine precipitates measured by LC completely coincided with the retention time of the stilbene bisphenol including the 26XY residue and the 3M6B residue ((including 26XY and 3M6B)) in its molecular structure, which was obtained in the process (2) of Example 3. Infrared absorption spectrum gave a broad absorption band due to the hydroxyl group in the vicinity of 3500cm -1 . A fragment of the molecular weight=310 was observed by mass spectrometry. * Melting point: 175 through 179 °C *1H-NMR &D: 1.43 ppm (s, t-butyl group, 9H) 2.27 ppm (s, Ar-CH 3 , 6H) 2.33 ppm (s, Ar-CH 3 , 3H) 4.77 ppm (brs, hydroxyl group, 2H) 6.5 - 7.5 ppm (m, Ar-H, -CH=CH-, 6H) (4) Synthesis of epoxy resin - 5 The epoxidation was carried out in the same manner as Reference 1(3), except that 99.7 g of XMSB-50 obtained in the above process (2) was used in place of XYSB, to gave 131 g of final product (yield: 94%) (hereinafter referred to as XMCC-50E). GPC (detected with a differential refractometer) showed that the purity of the product was 93.5% and the rate of the stilbene epoxy compound including the 26XY residue and the 3M6B residue in its molecular structure was 80.5%. The product had the melting point of 45 °C, the epoxy equivalent weight of 226 g/eq, and the melt viscosity of 0.02 Pa·s (0.2 poise) at 150 °C. Infrared spectroscopy showed that the absorption due to the phenolic hydroxyl group disappeared and that the product had absorptions of 1260cm -1 and 920cm -1 due to the epoxy group. (5) Synthesis of epoxy resin - 6 The epoxidation was carried out in the same manner as Reference 1(3), except that 38.8 g of the recrystallized product obtained in the above process (3) of Example 3 was used in place of XYSB, to gave 50.2 g of pale yellow viscous liquid substance (yield: 95%). The purity measured by LC was 94.2% for the stilbene epoxy compound including the 26XY residue and the 3M6B residue ((including 26XY and 3M6B)) in its molecular structure. Infrared spectroscopy showed that the absorption due to the phenolic hydroxyl group disappeared and that the product had absorptions of 1260cm -1 and 910cm -1 due to the epoxy group.*1H-NMR &D: 1.42 ppm (s, t-butyl group, 9H) 2.32 ppm (s, Ar-CH 3 , 6H) 2.38 ppm (s, Ar-CH 3 , 3H) 2.7 - 3.0 ppm (m, epoxy-CH 2 , 4H) 3.4 ppm (m, epoxy-CH, 2H) 3.7 - 4.3 ppm (m, -OCH 2 , 4H) 6.6 - 7.5 ppm (m, Ar-H, -CH=CH-, 6H) Example 4 (1) Synthesis of 1,1-bis(hydroxyphenyl)-2-chloroethane derivative - 6 Synthesis was carried out in the same manner as Reference 1(1), except that 91.7 g (0.75 mol) of 26XY and 205.4 g ((164.3 g)) (1.25 mol) of 3M6B were used in place of 244.4 g (2.0 mol) of 26XY, to gave 315 g of pale purple precipitates (yield: 88.0%) (hereinafter referred to as XMCE-62.5). GPC (detected with the ultraviolet ray of 254 nm) showed that the purity of the product was 94.4%, while infrared absorption spectrum gave broad absorption bands due to the hydroxyl group in the vicinity of 3450cm -1 and 3550cm -1 . Fragments of the molecular weight=346, 389, and 304 were observed by mass spectrometry. (2) Synthesis of stilbene bisphenol - 6Synthesis was carried out in the same manner as Reference 1(2), except that 121.1 g of XMCE-62.5 obtained in the above process (1) was used in place of XYCE, to gave 103 g of pale brown precipitates (yield: 94.7%) (hereinafter referred to as XMSB-62.5). GPC (detected with the ultraviolet ray of 254 nm) showed that the purity of the product was 92.0%, while infrared absorption spectrum gave a broad absorption band due to the hydroxyl group in the vicinity of 3500cm -1 . Fragments of the molecular weight=310, 268, and 352 were observed by mass spectrometry. (3) Synthesis of epoxy resin - 7 The epoxidation was carried out in the same manner as Reference 1(3), except that 80.3 g of XMSB-62.5 obtained in the above process (2) of Example 4 was used in place of XYSB, to gave 95.2 g of final product (yield: 87.9%) (hereinafter referred to as XMCC-62.5E). GPC (detected with a differential refractometer) showed that the purity of the product was 85.8% and the rate of the stilbene epoxy compound including the 26XY residue and the 3M6B residue ((including 26XY and 3M6B)) in its molecular structure was 71.0%. The product had the melting point of 105 through 125 °C, the epoxy equivalent weight of 230 g/eq, and the melt viscosity of 0.04 Pa·s (0.4 poise) at 150 °C. Infrared spectroscopy showed that the absorption due to the phenolic hydroxyl group disappeared and that the product had absorptions of 1260cm -1 and 915cm -1 due to the epoxy group. Example 5: Test for Solubility of Epoxy Resins in Solvent Solubility of the epoxy resins obtained in Examples 1, 2, 3, and 4 and References 1 and 2 (XMCC-20E, XMCC-30E, XMCC-50E, XMCC-62.5E, XMCC-100E, XYCC-E) was measured by adding 80 parts by weight of methyl isobutyl ketone to 20 parts by weight of each epoxy resin and heating each solution to 80 °C. As for the epoxy resins obtained in References 1 and 2, solubility was also measured when 10 parts by weight of each epoxy resin was mixed with 80 parts by weight of methyl isobutyl ketone. The results of measurement are shown in Table 1, where open circles and crosses represent 'dissolved' and 'not dissolved', respectively. Melting points of the respective epoxy resins are also given in Table 1. Epoxy Resins Melting Point Solubility XMCC-20E 110-130 °C ○ XMCC-30E Semisolid at room temperature ○ XMCC-50E 45 °C ○ XMCC-62.5E 105-125 °C ○ XMCC-100E 220-224 °C X XYCC-E 151 °C X XMCC-100E/XYCC-E 151-160 °C X Reference 3 (1) Synthesis of 1,1-bis(hydroxyphenyl)-2-chloro ethane derivative - 7 In a 2-liter four-necked flask with a thermometer, a stirrer, and a condenser, 244.4 g (2.0 mol) of 2,6-xylenol (hereinafter referred to as 26XY) and 124.5 g (1.0 mol) of chloroacetaldehyde dimethylacetal were added to and dissolved in 376 g of acetic acid with stirring, and the reaction solution was then cooled to 5 °C. A solution prepared by mixing 122 g (1.2 mol) of concentrated sulfuric acid with 84 g of acetic acid was added dropwise to the reaction solution at 10 °C over 3 hours. The reaction system was then maintained at the constant temperature of 25 °C for 6 hours, and stirred overnight at ambient temperature. The reaction system was again cooled to 5 °C, and deposited precipitates were filtered off. The precipitates thus obtained were washed with 500 g of water six times and dried in vacuo at 40 °C for 8 hours to give 268 g of pale purple precipitates. (2) Synthesis of stilbene bisphenol - 7 After 245.2 g of an 48.3% aqueous solution of sodium hydroxide and 552 g of N-methylpyrrolidone were placed in a 2-liter four-necked flask with a thermometer, a stirrer, and a condenser, the atmosphere in the flask was replaced with nitrogen. The solution was heated to 140 °C under the nitrogen encapsulating condition. A solution mixture prepared by mixing 225.6 g of the phenol intermediate obtained in the above process (1) of Reference 3 ((Reference 3)) with 676 g of N-methylpyrrolidone was added dropwise to the heated solution at 140 °C over 1.5 hours and maintained at the same temperature for 2 hours. The reaction system was cooled to 60 °C and neutralized with 226 g of concentrated hydrochloric acid. After removal of the solvent under reduced pressure, 1000g of ion-exchanged water was added to the reaction mixture, and precipitates thus deposited were filtered off. The precipitates obtained were washed with ion-exchanged water three times and dried in vacuo at 80 °C for 8 hours to give 190 g of yellow precipitates. (3) Synthesis of epoxy resin - 8 In a reaction vessel with a thermometer, a stirrer, a dropping funnel, and a columned condenser, 100 g of the material phenol obtained in the above process (2) of Reference 3 ((Reference 3)) was dissolved in 485.6 g of epichlorohydrin and 243.1 g of dimethyl sulfoxide. While the reaction system was kept at 43 torr, 61.71 g of a 48.3% aqueous solution of sodium hydroxide was continuously added dropwise over 5 hours at the temperature of 48 °C. The reaction proceeded at the fixed temperature of 48 °C, while the azeotropic mixture of epichlorohydrin and water was cooled and liquefied and the organic phase was returned to the reaction system.After completion of the reaction, unreacted epichlorohydrin was removed by evaporation under reduced pressure. By-product salts and the glycidyl ether including dimethyl sulfoxide thus obtained were dissolved in 644 g of methyl isobutyl ketone and washed with water for removal of the by-product salts and dimethyl sulfoxide. Subsequent removal of methyl isobutyl ketone at 160 °C under the reduced pressure of 1.33 kPa (10 torr) gave a final product (hereinafter referred to as XYCC-E). The product had the melting point of 151 °C, the epoxy equivalent weight of 198 g/eq, and the hydrolytic chlorine of 170 ppm. Example 6 Synthesis of epoxy resin - 9 An intermediate and then a material phenol were obtained in the same manner as Reference 3, except that 195.5 g (1.6 mol) of 26XY and 65.7 g (0.4 mol) of 3M6B were used in place of 244.4 g (2.0 mol) of 26XY, and the material phenol was epoxidized according to the process of Reference 3 to yield a final product (hereinafter referred to as XMCC-20E). The product had the melting point of 110 to 130 °C, the epoxy equivalent weight of 208 g/eq, and the hydrolytic chlorine of 170 ppm. The melt viscosity was 0.01 Pa·s (0.1 poise) at 150 °C. Example 7 Synthesis of epoxy resin - 10 An intermediate and then a material phenol were obtained in the same manner as Reference 3, except that 171.1 g (1.4 mol) of 26XY and 98.6 g (0.6 mol) of 3M6B were used in place of 244.4 g (2.0 mol) of 26XY, and the material phenol was epoxidized according to the process of Reference 3 to yield a final product (hereinafter referred to as XMCC-30E). The product was semisolid at room temperature and had the epoxy equivalent weight of 200 g/eq and the hydrolytic chlorine of 190 ppm. The melt viscosity was 0.016 Pa·s (0.16 poise) at 150 °C. Example 8 Synthesis of epoxy resin - 11 An intermediate and then a material phenol were obtained in the same manner as Reference 3, except that 122.2 g (1.0 mol) of 26XY and 164.3 g (1.0 mol) of 3M6B were used in place of 244.4 g (2.0 mol) of 26XY, and the material phenol was epoxidized according to the process of Reference 3 ((Reference 4)) to yield a final product (hereinafter referred to as XMCC-50E). The product had the melting point of 45 °C, the epoxy equivalent weight of 226 g/eq, and the hydrolytic chlorine of 170 ppm. The melt viscosity was 0.02 Pa·s (0.2 poise) at 150 °C. Example 9 Synthesis of epoxy resin - 12 An intermediate and then a material phenol were obtained in the same manner as Reference 3, except that 91.7 g (0.75 mol) of 26XY and 205.4 g ((164.3 g)) (1.25 mol) of 3M6B were used in place of 244.4 g (2.0 mol) of 26XY, and the material phenol was epoxidized according to the process of Reference 3 ((Reference 4)) to yield a final product (hereinafter referred to as XMCC-62.5E). The product had the melting point of 105 to 125 °C, the epoxy equivalent weight of 230 g/eq, and the hydrolytic chlorine of 180 ppm. The melt viscosity was 0.04 Pa·s (0.4 poise) at 150 °C. Example 10 Synthesis of epoxy resin - 13 An intermediate and then a material phenol were obtained in the same manner as Reference 3, except that 328.5 g (2.0 mol) of 3M6B was used in place of 244.4 g (2.0 mol) of 26XY, and the material phenol was epoxidized according to the process of Reference 3 ((Reference 4)) to yield a final product (hereinafter referred to as XMCC-100E). The product had the melting point of 220 to 224 °C, the epoxy equivalent weight of 230 g/eq, and the hydrolytic chlorine of 130 ppm. ((hereinafter referred to as XMCC-100E)). Examples 11 - 14 and Controls 1 - 3 Each of the glycidyl ethers obtained in Reference 3 and Examples 6 through 10 ((References 6 through 10)) or a commercially available glycidyl ether of 4,4'-dihydroxy-3,3 ',5,5'-tetramethylbiphenyl (manufactured by SUMITOMO CHEMICAL CO., LTD.) was mixed with phenol novolak (trade name: Tamanol 758 manufactured by Arakawa Chemical Industries Co., Ltd.) working as a curing agent, triphenylphosphine working as a curing accelerator, molten silica (the grade and composition are shown below) as fillers, and carnauba wax and a coupling agent (trade name: SH-6040 manufactured by Toray Dowcorning Silicone Co., Ltd.) as mold parting agents, according to the composition (g) shown in Table 2. Each composition was subjected to milling under application of heat and subsequently to transfer molding. Cured objects were obtained after the 5-hour post curing process in a 180 °C oven. Physical properties of the cured objects were measured. The results of measurement are shown in Table 2. Grade and composition of molten silica. 1. FS-20: ground silica (average particle diameter: 5.6 µm) by DENKI KAKAGU KOGYO K.K. 2. Admafine SO-C2: spherical silica (average particle diameter: 0.4 µm) by Admatec Co., Ltd. 3. Silstar MK-06: spherical silica (average particle diameter: 4.9 µm) by Nippon Chemical Industrial Co., Ltd. 4. Excelica SE-40: spherical silica (average particle diameter: 40.4 µm) by Tokuyama Corp. A mixture containing 10% by weight of silica 1, 10.8% by weight of silica 2, 18% by weight of silica 3, and 61.2% by weight by silica 4 was used as fillers in Table 2. Example 15 Synthesis of epoxy resin - 14 An intermediate XMCE-20 and then a material phenol XMSB-20 were ((An intermediate XMCE-20 was)) obtained in the same manner as the processes (1) and (2) of Reference 3 ((Reference 3(1))), except that 195.5 g (1.6 mol) of 26XY and 65.7 g (0.4 mol) of 3M6B were used in place of 244.4 g (2.0 mol) of 26XY. The process (3) of Reference 3 was repeated using 80.8 g of the material phenol XMSB-20 ((the intermediate XMCE-20 instead of XMSB-20)) and 62.36 g, instead of 61.71g, of the 48.3 % aqueous solution of sodium hydroxide, to give 96.4 g of final product (yield: 97%) (hereinafter referred to as XMCC-20E). GPC (detected with a differential refractometer) showed that the purity of the product was 93.2% and the rate of the stilbene epoxy compound including the 26XY residue and the 3M6B residue ((26XY and 3M6B)) in its molecular structure was 39.5%. The product had the melting point of 110 through 130 °C and the epoxy equivalent weight of 208 g/eq. Infrared spectroscopy showed that the absorption due to the phenolic hydroxyl group disappeared and that the product had absorptions of 1240cm -1 and 920cm -1 due to the epoxy group. The hydrolytic chlorine was 280 ppm. Compared with the conventional stilbene epoxy resin compositions, the stilbene epoxy resin composition of the present invention has better working and molding properties and advantages in the handling process. The stilbene epoxy resin composition of the present invention has low hygroscopicity and excellent heat resistance and is favorably used as material for encapsulating electronic parts. Resin-encapsulated semiconductor devices utilizing the resin composition of the present invention have high resistance against solder cracking and do not cause package cracks even after the long-time water absorption. The present invention accordingly provides a encapsulating material having high reliability without damaging the molding conditions and working properties of the conventional encapsulating materials.

Claims: A stilbene bisphenol represented by the general formula (1), in which two different aryl groups are bound to a carbon-carbon double bond, wherein R 1 through R 8 independently represent acyclic or cyclic alkyl groups having 1 through 6 carbon atoms, hydrogen atom or halogen atoms, provided that each aryl group contains at least one acyclic or cyclic alkyl group having 1 through 6 carbon atoms. A stilbene epoxy resin represented by the general formula (2), in which two different aryl groups are bound to a carbon-carbon double bond, wherein R 1 through R 8 independently represent acyclic or cyclic alkyl groups having 1 through 6 carbon atoms, hydrogen atom or halogen atoms, provided that each aryl group contains at least one acyclic or cyclic alkyl group having 1 through 6 carbon atoms. A bisphenol mixture comprising a stilbene bisphenol represented by the general formula (1) in claim 1, and a stilbene bisphenol represented by the general formula (3) given below in which two identical aryl groups are bound to a carbon-carbon double bond, wherein R 9 through R 12 independently represent acyclic or cyclic alkyl groups having 1 through 6 carbon atoms, hydrogen atom or halogen atoms, provided that each aryl group contains at least one acyclic or cyclic alkyl group having 1 through 6 carbon atoms. An epoxy resin mixture having a melting point of not higher than 150 °C, said epoxy resin mixture comprising a stilbene epoxy resin in claim 2, and a stilbene epoxy resin represented by the general formula (4) given below in which two identical aryl groups are bound to a carbon-carbon double bond, wherein R 9 through R 12 independently represent acyclic or cyclic alkyl groups having 1 through 6 carbon atoms, hydrogen atom or halogen atoms, provided that each aryl group contains at least one acyclic or cyclic alkyl group having 1 through 6 carbon atoms A stilbene bisphenol in accordance with claim 1, wherein R 1 represents t-butyl group, and R 5 through R 8 represent independently acyclic alkyl groups other than t-butyl group, cyclic alkyl groups, hydrogen atoms or halogen atoms in the general formula (1) given above. An epoxy resin in accordance with claim 2, wherein R 1 represents a t-butyl group, and R 5 through R 8 represent acyclic alkyl groups other than t-butyl group, cyclic alkyl groups, hydrogen atoms or halogen atoms in the general formula (2) given above. An epoxy resin mixture in accordance with claim 4, said epoxy resin mixture having a melt viscosity of not greater than 1 poise at 150 °C. A method of preparing a bisphenol mixture of claim 3, said method comprising the steps of: conducting a 1,1-bis(hydroxyphenyl)-2-chloroethane derivative, which is obtained by a reaction of two or more phenols with chloroacetaldehyde in the presence of an acid substance, to a dehydrochlorination reaction and a rearrangement reaction in the presence of a basic substance. A method of preparing an epoxy resin mixture in accordance with claim 4, said method comprising the steps of: conducting a 1,1-bis(hydroxyphenyl)-2-chloroethane derivative, which is obtained by a reaction of two or more phenols with chloroacetaldehyde in the presence of an acid substance, to a dehydrochlorination reaction in the presence of a basic substance to yield a dihydroxystilbene derivative; and reacting said dihydroxystilbene derivative with an epihalohydrin in the presence of a basic substance. A method of preparing an epoxy resin mixture in accordance with claim 4, said method comprising the steps of: making a 1,1-bis(hydroxyphenyl)-2-chloroethane derivative, which is obtained by a reaction of two or more phenols with chloroacetaldehyde in the presence of an acid substance, react with an epihalohydrin in the presence of a basic substance. A method in accordance with either one of claims 9 and 10, wherein said phenols comprise two or more phenols selected among the group consisting of 2,6-xylenol, 2,4-xylenol, 3-methyl-6-t-butylphenol, and 2-methyl-6-t-butylphenol. A method in accordance with claim 11, wherein said phenols comprise a mixture of 2,6-xylenol and 3-methyl-6-t-butylphenol. An epoxy resin composition comprising: (A) a stilbene epoxy resin in accordance with either one of claims 2 and 4; and (B) a phenolic epoxy curing agent. An epoxy resin composition in accordance with claim 13, wherein said stilbene epoxy resin or epoxy resin mixture has a melting point of not higher than 150 °C. An epoxy resin composition in accordance with either one of claims 13 and 14, wherein R 1 represents a t-butyl group, and R 5 through R 8 independently represent acyclic alkyl groups other than t-butyl group or cyclic alkyl groups having 1 through 6 carbon atoms, hydrogen atoms, or halogen atoms in the general formula (2) given above. An epoxy resin composition in accordance with claim 13, wherein said stilbene epoxy resin represented by the general formula (2) given above comprises an epoxy resin selected among glycidyl ether compounds of 3-t-butyl-2,4'-d ihydroxy-3',5',6-trimethylstilbene and 3-t-butyl-4,4'-dihyd roxy-3',5',6-trimethylstilbene, said stilbene epoxy resin represented by The general formula (4) given above comprising an epoxy resin selected among glycidyl ether compounds of 4,4'-dihydroxy-3,3',5,5'-tetramethylstilbene, 4,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene, 2,2'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene, and 2,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene. An epoxy resin composition in accordance with claim 13, wherein the curing agent comprises a polyphenol resin having a melt viscosity of 1.5 poise or less at 150 °C. An epoxy resin composition in accordance with claim 17, wherein the polyphenol resin is represented by the general formula (5) wherein X represents single bond or methylene, Q represents phenylene or a divalent alicyclic moiety derived from dicyclopentadiene or limonene, and n represents an integer of 1 to 20. An epoxy resin composition in accordance with claim 17, wherein the curing agent further comprises phenol novolak. An epoxy resin composition furhter comprising (C) inorganic fillers, as well as said components (A) and (B) in accordance with any one of claims 13, 14, 15, 16, 17, 18 and 19. A resin-encapsulating semiconductor device manufactured by encapsulating a semiconductor element with an epoxy resin composition in accordance with claim 20.

Inventors: AKIBA MASATSUGU, HIRANO YASUHIRO, NAITOH SHIGEKI, NAKAMURA HIROSHI, YOKOTA AKIRA, AKIBA, MASATSUGU, HIRANO, YASUHIRO, NAITOH, SHIGEKI, NAKAMURA, HIROSHI, YOKOTA, AKIRA
Applicants: SUMITOMO CHEMICAL CO, SUMITOMO CHEMICAL COMPANY LIMITED
Application year: 1996
Main classification: C07C39
IPC codes: H01L23, C07D303, C07C39, C07D301, C08G59, H05K1