Method for fabricating quad flat non-leaded package structure with electromagnetic interference shielding function

A fabrication method of a QFN package structure with an EMI shielding function, comprising the steps of:

• providing a metal frame with a plurality of lead frames and a plurality of transverse and longitudinal connection strips, wherein each of the lead frames has a die pad, a plurality of supporting portions connecting to the die pad and a plurality of leads disposed at a periphery of the die pad and separated from the die pad by a predetermined distance, the lead frames being connected to the connections trips through the supporting portions and the leads thereof;
• mounting a chip on the die pad of each of the lead frames and electrically connecting the chips to the leads through a plurality of bonding wires;
• forming an encapsulant to encapsulate the connection strips, the chips, the bonding wires, the die pads, the leads and the supporting portions in a manner that bottom surfaces of the connection strips, the die pads, and the leads are exposed from the encapsulant;
• performing a first cutting process for cutting the encapsulant along the connection strips so as to form in the encapsulant a plurality of grooves for exposing the connection strips and a portion of the supporting portions;
• forming on a surface and in the grooves of the encapsulant a shielding film electrically connected to the supporting portions;
• and
• performing a second cutting process for cutting the shielding film and the metal frame along the grooves and the connection strips such that the shielding film encloses side surfaces of the encapsulant and is flush with side surfaces of the leads and the supporting portions.