Wafer level transfer molding and apparatus for performing the same

A method comprising:

• placing a package structure into an inner space of a mold chase, with top surfaces of device dies in the package structure contacting a release film in the mold chase, wherein the mold chase comprises:
• an injection port on a diameter of the mold chase;
• a first plurality of venting ports on a first side of the diameter;
• and
• a second plurality of venting ports on a second side of the diameter, wherein the second side is opposite to the first side, and the first plurality of venting ports and the second plurality of venting ports are symmetric with respect to the diameter;
• placing the package structure and the mold chase in a chamber, wherein each of the first plurality of venting ports and the second plurality of venting ports interconnects the inner space to a portion of the chamber outside of the mold chase;
• vacuuming the chamber;
• and
• injecting a molding compound into the inner space of the mold chase through the injection port;
• wherein the first and the second plurality of venting ports are increasingly smaller with reduction of respective distances to the injection port.

A method comprising:

• placing a package structure into a mold chase, wherein the mold chase comprises an edge forming an edge ring having a circular top-view shape, and the edge ring comprises:
• an injection port;
• an additional venting port, wherein the injection port and the additional venting port are on a diameter of the edge ring;
• and
• a first plurality of venting ports, wherein venting ports in the first plurality of venting ports farther away from the injection port are larger than respective venting ports in the plurality of venting ports closer to the injection port;
• and
• a second plurality of venting ports, wherein corresponding ports in the first plurality of venting ports and the second plurality of venting ports are symmetric to each other with respect to the diameter, and are located on opposite sides of the diameter;
• and
• injecting an encapsulating material into the injection port, and simultaneously venting air out of the first and the second plurality of venting ports.