Stack package and methods of manufacturing the same

A method of manufacturing a stack package, the method comprising:

• arranging a first surface of a first package substrate and a first surface of a second package substrate to face each other,
• wherein a first semiconductor device and a plurality of first conductive connection terminals are provided on the first surface of the first package substrate, and a molding resin material layer and a plurality of second conductive connection terminals corresponding to the plurality of first conductive connection terminals are provided on the first surface of the second package substrate, and the molding resin material layer contacts an upper surface of the first semiconductor device;
• and
• joining the first package substrate and the second package substrate by raising temperatures of the first package substrate and the second package substrate,
• wherein the joining of the first package substrate and the second package substrate by raising the temperatures of the first package substrate and the second package substrate comprises:
• reflowing the molding resin material layer so that the molding resin material layer contacts side surfaces of the first semiconductor device;
• and
• electrically connecting the first package substrate with the second package substrate, and
• wherein the step of reflowing of the molding resin material layer partially and temporally overlaps with the step of the electrically connecting of the first package substrate and the second package substrate.