Quad Flat Package (QFP) is popular among the quad packages. The reason is the fine etching or stamping lead frames enables QFP to contain more leads and feature a smaller profile to perform better electrical characteristics by shortening the interconnection (the lead width can be as small as 0.16mm while the outer lead pitch is 0.4mm only). The thinner and flexible leads in gull-wing shape also provide better 2nd-level reliability (package-to-PCB reliability).
The package with drop-in HS can allow more than 50% power dissipation compared with a conventional package (e.g. in QFP 28x28mm, the allowable power of standard type and the type with HS is about 2.1W and 3.5W respectively). This drop-in HS drives off the heat from the chip more easily by extending the conduction area, and transferring more heat via the lead frame. QFP with drop-in HS is to package sizes of 14x20, 28x28, and 32x32mm.