Leydig, Voit & Mayer
Epoxy resin containing an epoxy resin-modified silicone oil flexibilizer
 An epoxy resin composition for encapsulating a semiconductor device comprises a flexibilizer obtained by pre-reaction of an epoxy resin and at least one modified silicone oil having the formula: ##STR1## where R.sub.1, R.sub.3, and R.sub.4 are divalent organic groups; R.sub.21, R.sub.22, R.sub.23, R.sub.24, R.sub.25, R.sub.26, and R.sub.27 are respectively selected from the group consisting of an alkyl group having from 1 to 5 carbon atoms, a hydroxyalkyl group having from 1 to 5 carbon atoms, an alkoxy group having from 1 to 5 carbon atoms, a phenyl group, and a fluorine-substituted alkyl group having from 1 to 5 carbon atoms; a is an integer from 10 to 300; and b is an integer from 2 to 10, in which 0.ltoreq.b/(a+b).ltoreq.0.32, and wherein the equivalent ratio of phenolic hydroxyl groups in said modified silicone oil to epoxy groups of the epoxy resin of the flexibilizer is from 0.001 to 0.4:1; an epoxy resin other than the flexibilizer; and a curing agent. 
Mitsubishi Denki Kabushiki Kaisha
H H C H C C C C
H01L H01L C08G H01B C08L C08G C08G C08G
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Ichiro Hiromi
Takahashi Ito