Package structure and manufacturing method thereof

A manufacturing method of a package structure, comprising:

• providing a preliminary structure, comprising:
• a first die;
• an encapsulant, covering the first die, and having a first molding surface and a second molding surface opposite to the first molding surface;
• a first redistributed circuit structure, disposed on the first molding surface of the encapsulant;
• a second redistributed circuit structure, disposed on the second molding surface of the encapsulant and electrically connected to the first die, wherein an upper surface of the second redistributed circuit structure has a groove, and the upper surface comprises a first area and a second area disposed on two opposite sides of the groove;
• and
• a conductive connector, penetrating through the encapsulant and electrically connected to the first redistributed circuit structure and the second redistributed circuit structure;
• disposing a second die on the preliminary structure to be electrically connected to the second redistributed circuit structure, wherein the second die has an optical signal transmission area;
• and
• forming a filler between the second die and the second redistributed circuit structure, wherein the filler directly contacts the first area, and the filler is disposed away from the second area, wherein in a direction perpendicular to the first molding surface or the second molding surface, the optical signal transmission area of the second die is not overlapped with the encapsulant.