Lead frame

Lead frames are the metal structures inside a chip package that carry signals from the die to the outside.

Leadframe for a QFP package, before encapsulation

DIP 16 pin Leadframe, after encapsulation and before cutting/separation

Classically the leadframe consists of different parts; The central die pad part, where the die is to be placed, usually multiple bond pads, where the bond wires are placed to connect the chip to the outer part, and the leads, which are metal structures connecting the inside of the semiconductor package with the outside. Additionally there are mechanical connections to fix all these parts inside a frame structure, which makes the whole leadframe easy to handle automatically.
The die inside the package is typically glued or soldered to the die pad inside the lead frame, and then bond wires connect the die to the leads via the bond pads. In the last stage of the manufacturing process, the lead frame is moulded in a plastic case, and is cut-off outside of the mold body, separating all leads by removing the holding structures at least enough to achieve an electrical insulation. A bending of the external leads can form the usual shapes.