Method for producing encapsulated structure and epoxy resin composition

A method for producing an encapsulated structure, the method comprising:

• a step of supplying granules or powder formed from an epoxy resin composition to an extruder equipped with a screw and a die provided at a tip of the screw, and heating and melting the granules or powder formed from the epoxy resin composition;
• a step of extruding the molten epoxy resin composition through the die having a predetermined opening shape with a diameter of equal to or more than 40 mm and equal to or less than 100 mm by rotation of the screw at a temperature of equal to or higher than 80° C. and equal to or lower than 100° C., and wherein the die has a temperature of equal to or higher than 80° C. and equal to or lower than 100° C.;
• a step of cutting the extruded epoxy resin composition using a cutter into a predetermined length to obtain a tablet formed from the epoxy resin composition, where the tablet has dimensions with a diameter of equal to or more than 40 mm and equal to or less than 100 mm and a length of equal to or more than 50 mm and equal to or less than 300 mm;
• a step of transferring the tablet to a transfer molding machine having a molding mold in which an object to be encapsulated is disposed;
• and
• a step of obtaining an encapsulated structure by encapsulating the object to be encapsulated in the molding mold with the epoxy resin composition by a transfer molding method of using the transfer molding machine,
• wherein the epoxy resin composition includes:
• an epoxy resin;
• a curing agent;
• an inorganic filler;
• a curing accelerator;
• and
• a wax having a melting point of equal to or higher than 30° C. and equal to or lower than 90° C.