quad

**Quad Flat No-Lead QFN** is **small-outline package with leads replaced by pads on package sides and thermal pad bottom** — ultra-compact with superior thermal properties. **Structure** leadframe-based; die, bondwires, molding compound. **Leads** flat against sides; no lead-forming. Thermal pad on bottom. **Thermal Pad** large Cu pad (4×4 to 10×10 mm) dissipates to PCB. Θ_JA ~20-40°C/W. **Vias** PCB vias beneath thermal pad improve coupling. Via-filled pattern. **Leadframe** Cu plated Ni/Au or Sn for solderability. **Molding** epoxy plastic encapsulation. **Dimensions** ultra-compact footprints. QFN5 (1.4×1.4 mm) to QFN48+. **Land Pattern** PCB pads on all sides; solder reflow. **Solder Joints** tiny fillets; minimal solder. Sufficient. **Inspectability** hidden joints (unlike gull-wing). X-ray needed. **Rework** small package, hidden joints difficult to rework. Often not reworkable. **EMI** leadless design better EMC (no lead loops as antenna). **Cost** volume production mature; low cost. **Reliability** thermal cycling stresses; underfill optional for robustness. **Applications** microcontrollers, power management, sensors, RF modules. **QFN maximizes density** in compact form factor.