Lead-frame-based semiconductor package and fabrication method thereof

A lead-frame-based semiconductor package, comprising:

• a lead frame having a plurality of first leads and second leads, each lead having an upper surface and a lower surface opposed to the upper surface, wherein each of the first leads is formed with an extending portion smaller in thickness than the corresponding one of the first leads in a manner that, an upper surface of the extending portion is flush with the upper surface of the corresponding first lead, and a lower surface of the extending portion forms a predetermined height difference with respect to the lower surface of the corresponding first lead;
• at least a chip mounted over the upper surfaces of the extending portions;
• a plurality of bonding wires for electrically connecting the chip to the first and second leads;
• a first non-conductive material for encapsulating the upper surfaces of the first and second leads, the upper surfaces of the extending portions, the chip and the bonding wires;
• and
• a second non-conductive material applied over the lower surfaces of the extending portions, wherein the lower surfaces of the first and second leads are exposed to outside of the second non-conductive material.