the present invention relates to a resin composition for sealing a semiconductor device , the essential components of which are a glycidyl ether of a hydrogenated conjugated diene polymer ( i ), an epoxy resin ( ii ) and a reaction product of a phenolic compound with formaldehyde ( iii ); and a semiconductor device sealed with this resin composition . the examples of the epoxy resins ( ii ) include bisphenol type epoxy resins ( for example , diglycidyl ether of bisphenol - a ), phenol novolak epoxy resins ( for example , polyglycidyl ether of phenol novolak , polyglycidyl ether of phenol novolak modified with alkylbenzene ), cresol novolak epoxy resins ( for example , polyglycidyl ether of ortho - cresol novolak ), phenol epoxy resins ( for example , diglycidyl ether of resorcinol , triglycidyl ether of para - aminophenol , diglycidyl ether of phloroglucin and diglycidyl ether of methyl phloroglucin ), aromatic epoxy resins [ 1 , 3 , 5 - tri ( 1 , 2 - epoxyethyl ) benzene , 4 , 4 &# 39 ;- di ( 1 , 2 - epoxyethyl ) diphenyl ether , 4 , 4 &# 39 ;-( 1 , 2 - epoxyethyl ) biphenyl ], cycloaliphatic epoxy resins [ 3 , 4 - epoxycyclohexylmethyl -( 3 , 4 - epoxy ) cyclohexane carboxylate , 2 , 2 - bis ( 3 , 4 - epoxy - cyclohexyl ) propane , 2 -( 3 , 4 - epoxy ) cyclohexane - 5 , 5 - spiro ( 3 , 4 - epoxy ) cyclohexane - m - dioxane , bis -( 3 , 4 - epoxy - 6 - methyl - cyclohexyl ) adipate , n , n &# 39 ;- m - phenylenebis ( 4 , 5 - epoxy - 1 , 2 - cyclohexane ) dicarboxyimid ], the other epoxy resins [ butadiene diepoxide , di - and triglycidyl ether of trimethylol propane , di - and triglycidyl ether of glycerol , bis -( 2 , 3 - epoxy - cyclopentyl ) ether etc .]. the preferable among these are the epoxy resins of phenol novolak resins and cresol novolak resins . the molecular weight of ( ii ) is usually from about 100 to about 1 , 500 , preferably from about 200 to about 1 , 000 . the epoxy equivalent weight of ( ii ) is usually from 50 to 1 , 000 g / eq , preferably 100 to 300 g / eq . the phenolic compounds which are used for the reaction product ( iii ) with formaldehyde are given examples by phenol , cresols , xylenols , bisphenol - a , bisphenol - f , resorcinol , catechol , hydroquinone , pyrogallol etc ., preferably , phenol and cresol . ( iii ) is prepared by a condensation reaction of phenolic compounds with formaldehyde under an acidic catalyst . the reaction temperature is usually 50 to 100 degrees c ., and the reaction time is usually 1 to 10 hours . the molecular weight of ( iii ) is usually from about 200 to about 1 , 500 , preferably , about 300 to about 1 , 000 . the preferable reaction product ( iii ) is a phenol novolak resin . in the glycidyl ether of hydrogenated conjugated diene polymers ( i ), the conjugated diene polymers are given examples by conjugated diene homopolymers , conjugated diene copolymers and conjugated diene olefinic hydrocarbon copolymers . the glycidyl ether of conjugated diene homopolymers is given examples by a glycidyl ether of hydrogenated butadiene polymers ( glycidyl ether of hydrogenated polybutadiene glycol etc . ), a glycidyl ether of hydrogenated isoprene polymers ( glycidyl ether of hydrogenated polyisoprene glycol etc . ), a glycidyl ether of hydrogenated 1 , 3 - pentadiene glycol and a glycidyl ether of hydrogenated polycyclopentadiene glycol . besides , a glycidyl ether of triol or mono - ol may be used . example of suitable glycidyl ethers of conjugated diene copolymers include glycidyl ethers of hydrogenated copolymers , of butadiene and isoprene such as glycidyl ethers of hydrogenated poly ( butadieneisoprene ) glycol and glycidyl ethers of corresponding of triol or mono - ol . the glycidyl ethers of copolymers of conjugated dienes and olefinic hydrocarbons include glycidyl ethers of hydrogenated poly ( butadiene - styrene ) glycol and glycidyl ethers of hydrogenated poly ( isoprene - styrene ) glycol . the preferable among these are the glycidyl ethers of hydrogenated polybutadiene glycol and that of hydrogenated polyisoprene glycol . the structural units in the homopolymers and copolymers of butadiene [ hereinafter referred to as butadiene ( co ) polymer ] include 1 , 2 - butadiene and 1 , 4 - butadiene , and may include either or both at an arbitrary proportion . the preferable is the one containing at least 70 % of 1 , 2 - butadiene structural unit and the more preferable is the one containing at least 85 % of 1 , 2 - butadiene structural unit . manufacturing of the glycidyl may be done by any known method including a one - stage or two - stage process . in the one - step process , the glycidyl ether can be usually produced by a reaction of the hydrogenated conjugated diene polymer containing hydroxyl group with epichlorohydrin at 30 to 70 degrees c . in the presence of sodium hydroxide . with the two - step method , it can be synthesized first by an addition reaction of the hydrogenated conjugated diene polymer containing hydroxyl group with epichlorohydrin under a catalyst , and then by removing hydrogen chloride with caustic alkali . the preferable is the one - step method making a product of less total chlorine content . the number average molecular weight of glycidyl ether ( i ) is usually from about 500 to about 10 , 000 , preferably , about 1 , 000 to about 5 , 000 . in the range less than about 500 , the thermal stress reducing effect is not enough . in the range over about 10 , 000 , it has not an enough solubility into the resin composition for sealing and therefore can not effect an enough reduction of the thermal stress . the epoxy equivalent weight of ( i ) is usually from 200 to 10 , 000 g / eq , preferably , 500 to 5 , 000 g / eq . in this invention , the equivalent ratio of epoxy groups in ( ii ) and ( i ) to phenolic hydroxyl groups in ( iii ) is usually from 0 . 6 to 1 . 4 , preferably , 0 . 75 to 1 . 25 . in the cases less than 0 . 6 and over 1 . 25 , there is no good balance in a curing reaction between epoxy group and phenolic hydroxyl group and eventually no product of enough strength can be obtained . also , the content of ( i ) in this invention usually ranges from about 1 to about 50 weight % for the total weight of ( i ), ( ii ) and ( iii ), preferably , from about 2 to about 30 weight %. when it is less than about 1 weight %, the stress reduction is not effected sufficiently , and when it is over about 50 weight % the heat resistivity is not enough . in addition , the content of ( i ) in this invention usually ranges from about 1 to about 70 weight % for the weight of ( ii ), preferably , about 2 to about 50 weight %. the resin composition of this invention can be compounded with a curing accelelerator . example of a curing accelerator include phosphorous compounds , such as triphenyl phosphine , triphenyl phosphite , imidazoles such as 2 - methylimidazole , 2 - phenylimidazole , 2 - undecylimidazole , 2 - heptadecylimidazole , 2 - ethyl - 4 - methylimidazol , tertiary amines such as 2 -( dimethyl aminomethyl ) phenol , 2 , 4 , 6 - tris ( dimethyl aminomethyl ) phenol , benzyldimethyl amine , α - methylbenzylmethyl amine , 1 , 8 - diazabicyclo ( 5 , 4 , 0 ) undecene - 7 . the dosage of the curing accelerator is usually from 0 . 1 to 5 . 0 parts by weight for 100 parts of ( ii ) by weight , preferably , 0 . 2 to 3 . 0 parts by weight . furthermore , the resin composition of this invention , if required , can contain one or more additives , for example , fillers such as crystalline silica powder , quartz glass powder and alumina ; releasing agents such as higher fatty acids or their metal salts , natural waxes , synthetic waxes and paraffin ; coupling agents such as epoxysilane and vinylsilane ; and fire retardants such as antimony phosphorus compounds . the dosage of filler usually ranges from 200 to 800 parts by weight for 100 parts of ( ii ) by weight . the releasing agent , coupling agent and fire retardant are added by from 0 . 1 to 5 parts by weight for 100 parts of ( ii ) by weight respectively . the manufacturing method of the abovementioned resin composition for sealing a semiconductor device according to the present invention is adhered by two blending methods . the first one comprising blending ( i ), ( ii ), ( iii ) and the other additives simultaneously , and the second one comprises blending a preliminary reaction product of ( i ) with ( iii ) beforehand , with ( ii ) and the other additives . the preferable is the latter method . in the preliminary reaction between ( i ) and ( iii ), the preliminary reaction product can be obtained by adding phosphorus compounds , amines or imidazoles as a catalyst to a mixture of ( i ) and ( iii ) under the condition of usually from 100 to 170 degrees c . and from 1 to 20 hours in the nitrogen atmosphere . the resin composition of this invention can be obtained by a series of procedures , in which the compounds made by the above - mentioned reactions are kneaded by a kneading machine such as hot rollers and then cooled , pulverized and , if required , made into a tablet . the resin composition of this invention can be used , if required , by a partial curing ( b stage , half - cured state ). the partial curing can be carried out usually under the conditions from 50 to 150 degrees c . and from 5 minutes to 5 hours . the sealing of semiconductor devices with the resin composition of this invention is not particularly limited to , but can be carried out by the ordinary well - known molding method such as a transfer molding . in case of the transfer molding , the molding conditions are usually the pressure of 50 to 90 kg / sq . cm , the temperature from 160 to 200 degrees c . and the time from 60 to 180 seconds . the semiconductor devices sealed with the resin composition of this invention as abovementioned have the characteristics of low internal stress of sealing resin and reduction of packaging cracks . this invention is explained further by the following examples but not limited to these . the part in the examples and reference examples means the part by weight . 100 parts of hydrogenated polyisoprene glycol ( pip - h , average molecular weight of 2 , 500 , made by idemitsu petrochemicals corp . japan ), 35 parts of epichlorohydrin , 16 parts of pelletized sodium hydroxide , 1 part of benzyl trimethyl ammonium chloride and 50 parts of toluene were fed and reacted under a vigorous stirring at 50 degrees c . for 5 hours in the nitrogen atmosphere . after the reaction , 100 parts of water were added and the product was washed while stirring for 10 minutes . after laying it quietly , the upper layer was separated and filtered , and then the remaining epichlorohydrin and toluene were removed under vacuum . thus 90 parts of glycidyl ether of hydrogenated polyisoprene glycol ( a ) was obtained as a residue . this glycidyl ether ( a ) had an epoxy equivalent weight of 1 , 650 g / eq . 100 parts of hydrogenated polyisoprene glycol ( pip - h , average molecular weight of 2500 , made by idemitsu petrochemicals corp . japan ), 9 parts of epichlorohydrin , 0 . 15 part of trifluoroborondiethylether complex and 50 parts of toluene were fed and carried out addition reaction under vigorous stirring at 55 degrees c . for 5 hours in the nitrogen atmosphere . then , 9 . 5 parts of 48 % aqueous solution of sodium hydroxide were added and a ring - closing reaction was carried out at 65 degrees c . for 5 hours . after the reaction 100 parts of water were added and the following procedures were carried out same as described in reference example no . 1 and 95 parts of glycidyl ether of hydrogenated polyisoprene glycol ( b ) were obtained . the glycidyl ether ( b ) had an epoxy equivalent weight of 1 , 430 g / eq . 100 parts of hydrogenated polybutadiene glycol ( polytale h , average molecular weight of 2 , 370 , 1 , 2 - butadiene structural unit to that of 1 , 4 - butadiene is 20 / 80 , made by mitsubishi chemical ind . co . ltd ., japan ), 12 parts of epichlorohydrin , 0 . 2 part of trifluoroboron - diethyl ether complex and 100 parts of toluene were fed , and the reaction and the following procedures were carried out same as reference example no . 2 , and 85 parts of glycidyl ether of hydrogenated polybutadiene glycol ( c ) were obtained . the glycidyl ether ( c ) had an epoxy equivalent weight of 1 , 520 g / eq . 100 parts of hydrogenated polybutadiene glycol ( nisso pb g1 - 1000 , average molecular weight of 1 , 450 , 1 , 2 - butadiene structural unit to that of 1 , 4 - butadiene is 90 / 10 , made by nihon soda co . ltd ., japan ), 25 parts of epichlorohydrin , 10 parts of pelletized sodium hydroxide , 1 part of benzyltrimethylammonium chloride and 50 parts of toluene were fed , reacted and followed by the procedures same as reference example no . 1 , thus 90 parts of glycidyl ether o hydrogenated polybutadiene glycol ( f ) were obtained . the glycidyl ether ( f ) had an epoxy equivalent weight of 1 , 030 g / eq . 100 parts of hydrogenated polybutadiene glycol ( nisso pb g1 - 2000 , average molecular weight of 2 , 500 , 1 , 2 - butadiene structural unit to that of 1 , 4 - butadiene is 90 / 10 , made by nihon soda co . ltd . ), 30 parts of epichlorohydrin , 13 parts of pelletized sodium hydroxide , 1 part of benzyltrimethylammonium chloride and 50 parts of toluene were fed , reacted and followed by the procedures same as reference example no . 1 , thus 85 parts of glycidyl ether of hydrogenated polybutadiene glycol ( g ) were obtained . the glycidyl ether ( g ) had an epoxy equivalent weight of 1 , 800 g / eq . 100 parts of hydrogenated poly ( butadiene - isoprene ) glycol [ a product of polymerization reaction between 50 mole % of butadiene and 50 mole % of isoprene at 80 degrees c . for 5 hours by using hydrogen peroxide as a catalyst , its average molecular weight of 2900 , 1 , 2 - butadiene structural unit to that of 1 , 4 - butadiene is 20 / 80 ], 40 parts of epichlorohydrin , 18 parts of pelletized sodiuma hydroxide , 1 part of benzyltrimethylammonium chloride and 70 parts of toluene were fed , reacted and followed by the procedures same as reference example no . 1 , thus 80 parts of glycidyl ether of hydrogenated poly ( butadiene - isoprene ) glycol ( h ) were obtained . the glycidyl ether ( h ) had an epoxy equivalent weight of 1 , 950 g / eq . 100 parts of phenol novolak resin ( tamanol 758 , made by arakawa chemicals co . ltd ., japan ), 20 parts of glycidyl ether of hydrogenated polyisoprene glycol ( a ) synthesized in reference example no . 1 and 1 part of triphenyl phosphine were reacted at 150 degrees c . for 3 hours under the purging of nitrogen to a product of preliminary reaction ( d ). 100 parts of phenol novolak resin ( tamanol 758 , made by arakawa chemicals co . ltd . ), 40 parts of glycidyl ether of hydrogenated polybutadiene glycol ( c ) synthesized in reference example no . 3 and 0 . 5 parts of 2 - ethyl - 4 - methylimidazole were reacted at 160 degrees c . for 2 hours under the purging of nitrogen to a product of preliminary reaction ( e ). 100 parts of phenol novolak resin ( tamanol 758 , made by arakawa chemicals co . ltd . ), 40 parts of glycidyl ether of hydrogenated polybutadiene glycol ( f ) synthesized in reference example no . 4 and 0 . 5 part of triphenyl phosphine were reacted at 150 degrees c . for 3 hours under the purging of nitrogen to a product of preliminary reaction ( i ). 100 parts of phenol novolak resin ( tamanol 758 , made by arakawa chemicals co . ltd . ), 40 parts of glycidyl ether of hydrogenated polybutadiene glycol ( g ) synthesized in reference example no . 5 and 1 part of 1 . 8 - diazabicyclo ( 5 , 4 , 0 ) undecene - 7 were reacted at 150 degrees c . for 2 hours under the purging of nitrogen to a product of preliminary reaction ( j ). 100 parts of phenol novolak resin ( tamanol 758 , made by arakawa chemicals co . ltd . ), 40 parts of glycidyl ether of hydrogenated poly ( butadiene - isoprene ) glycol ( h ) synthesized in reference example no . 6 and 1 part of triphenyl phosphine were reacted at 150 degrees c . for 2 hours under the purging of nitrogen to a product of preliminary reaction ( k ). a cresol novolak epoxy resin ( sumiepoxy escn 220l , epoxy equivalent of 210 g / eq , made by sumitomo chemicals co . ltd ., japan ), a phenol novolak resin ( tamanol 758 , made by arakawa chemicals co . ltd . ), the glycidyl ether of hydrogenated polyisoprene glycol ( a ) synthesized in reference example no . 1 , triphenyl phosphine as a curing accelerator , fused silica as fillers , silane coupling agent , carnauba wax , antimony trioxide and carbon black were mixed by the recipe shown in table 1 , kneaded with hot rollers , cooled down and pulverized into the resin composition of this invention . the resin composition obtained herein was molded under the conditions of 175 degrees c ., and 3 minutes . it was postcured at 180 degrees c . for 16 hours to make a cured test piece . the cured test piece obtained was determined for bending elasticity , glass transition temperature , and volumetric resistivity before and after pressure - cooker test at 120 degrees c ., 2 atmospheric pressures and for 200 hours . the result is shown in table 2 . also , by using the resin composition obtained herein , a silicon semiconductor element was molded on a 48 pin flat package by means of the transfer molding at 175 degrees c ./ 120 seconds , and then it was after - cured at 175 degrees c ./ 5 hours . the semiconductor devices ( each 10 pieces ), which were obtained as stated above and shown in fig1 were determined the number of package cracks by means of the temperature cycle test ( tct ), 1 , 000 times of which were carried out at - 196 degrees c ./ 2 minutes to 150 degrees c ./ 2 minutes . the result is shown in table 2 . in fig1 indicates lead frame , 2 : semiconductor element , 3 : bonding wire , 4 : die pad , 5 : protecting cover , 6 : sealing resin . the glycidyl ether of hydrogenated polyisoprene glycol ( b ), which was synthesized in reference example no . 2 , was used as ( i ). except it , a resin composition was made by the recipe shown in table 1 . except it , a resin composition was prepared and evaluated by carrying out all the other procedures same as example no . 1 . the result is shown in table 2 . the glycidyl ether of hydrogenated polybutadiene glycol ( c ) was used as ( i ). except it , a resin composition was prepared by the recipe shown in table 1 . except it , a resin composition was prepared and evaluated by carrying out all the other procedures same as example no . 1 . the result is shown in table 2 . a cresol novolak epoxy resin ( sumiepoxy - escn 220l , epoxy equivalent weight of 210 g / eq , made by sumitomo chemicals co . ltd . ), the preliminary reaction product ( d ) prepared in reference example no . 7 , triphenyl phosphine as a curing accelerator , fused silica as fillers , a silane coupling agent , carnauba wax , antimony trioxide and carbon black were mixed by the recipe shown in table 1 . except it , a resin composition was prepared and evaluated by carrying out all the other procedures same as example no . 1 . the result is shown in table 2 . except that the preliminary reaction product ( e ) prepared in reference example no . 8 was used , all the other procedures were carried out same as example no . 4 and a resin composition was prepared by the recipe shown in table 1 and evaluated . the result is shown in table 2 . except that the preliminary reaction product ( i ) prepared in reference example no . 9 was used , all the other procedures were carried out same as example no . 4 and a resin composition was prepared by the recipe shown in table 1 and evaluated . the result is shown in table 2 . table 1______________________________________ com - pari - examples son1 2 3 4 5 6 7 8 1______________________________________i 100 100 100 100 100 100 100 100 100ii 50 50 50 -- -- -- -- -- 50iii 10 -- -- -- -- -- -- -- -- iv -- 30 -- -- -- -- -- -- -- v -- -- 20 -- -- -- -- -- -- vi -- -- -- 60 -- -- -- -- -- vii -- -- -- -- 70 -- -- -- -- viii -- -- -- -- -- 70 -- -- -- ix -- -- -- -- -- -- 70 -- -- x -- -- -- -- -- -- -- 70 -- xi 1 1 1 1 1 1 1 1 1xii -- -- -- -- -- -- 1 1 -- xiii 300 300 300 300 300 300 300 300 300xiv 1 1 1 1 1 1 1 1 1xv 1 1 1 1 1 1 1 1 1xvi 2 2 2 2 2 2 2 2 2xvii 1 1 1 1 1 1 1 1 1______________________________________ remarks : i : cresol novolak epoxy resin ii : phenol novolak resin iii : glycidyl ether of hydrogenated polyisopreneglycol ( a ) iv : glycidyl ether of hydrogenated polyisopreneglycol ( b ) v : glycidyl ether of hydrogenated polybutadieneglycol ( c ) vi : preliminary reaction product shown in reference example no . 7 ( d ) vii : preliminary reaction product shown in reference example no . 8 ( e ) viii : preliminary reaction product shown in reference example no . 9 ( i ) ix : preliminary reaction product shown in reference example no . 10 ( j ) x : preliminary reaction product shown in reference example no . 11 ( k ) xi : triphenyl phosphine xii : 1 , 8diazabicyclo ( 5 , 4 , 0 ) undecene - 7 xiii : fused silica xiv : silane coupling agent xv : carnauba wax xvi : antimony trioxide xvii : carbon black table 2______________________________________ volumetric glass tran - resistivity tctexam - bending sition tem - first pressure - test / ple elasticity perature stage cooker test 10no . ( kg / mm . sup . 2 ) (° c .) ( ω cm × 10 . sup . 15 ) pieces______________________________________1 1250 167 64 5 . 0 0 / 102 1150 162 72 6 . 9 1 / 103 1220 165 65 5 . 3 1 / 104 1260 167 66 5 . 2 0 / 105 1280 166 62 4 . 7 1 / 106 1290 166 67 6 . 0 0 / 107 1250 164 69 6 . 2 0 / 108 1270 165 65 5 . 9 0 / 10comparison example1 1600 168 55 4 . 3 10 / 10______________________________________ except that the preliminary reaction product ( j ) prepared in reference example no . 10 was used , all the other procedures were carried out same as example no . 4 and a resin composition was prepared by the recipe shown in table 1 and evaluated . the result is shown in table 2 . except that the preliminary reaction product ( k ) prepared in reference example no . 11 was used , all the other procedures were carried out same as example no . 4 and a resin composition was prepared by the recipe shown in table 1 and evaluated . the result is shown in table 2 . except that ( i ) was not added , all the other procedures were carried out same as example no . 1 , and a resin composition was prepared by the recipe shown in table 1 and evaluated . the result is shown in table 2 .