Abstract: A “paddle-under-lead” (PUL) leadframe has the inner portions of an I.C. package's leads extend along the top of a paddle, to which they are affixed. An I.C. die is affixed to the top of the inner leads to form an I.C. package. Because the die is affixed directly to the leads, heat generated by the die is conducted out of the package via the package's leads, with the paddle serving as a heat spreader and heat sink. The leadframe's inner leads are affixed to the paddle, rather than separated from it as is done conventionally; this enables a larger die size to be accommodated within the same standard package size. A bifurcated inner lead design, usable with the PUL leadframe and others, divides the inner portions of an I.C. package's leads into laterally offset upper and lower sections, with the upper section serving as a wedge bond shelf and the lower section downset from the upper section.

Abstract: A "lead-under-paddle" (LUP) leadframe employs a thermally conductive paddle/heat sink, the top side of which is adhered to an I.C. die with a thermally conductive adhesive. The inner portions of an I.C. package's leads extend along and are attached to the bottom side of the paddle with a thermally conductive and electrically isolating adhesive. Heat generated by the die is conducted to the leads and out of the package via the paddle/heat sink. The leads are in close contact with the paddle and die, reducing the leadframe's thermal resistance, increasing the amount of power that can be consumed by the die, and enabling a standard I.C. package to accommodate a paddle and die having larger respective surface areas.