Importance

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Abstract

A dambar-less leadframe is sandwiched between two printed circuit boards (PCBs). The PCBs form a major portion of the package body, and isolate the leadframe leads from plastic molding compound. In one embodiment, an upper PCB (substrate) is formed as a square ring, having an opening containing a heat sink element. A lower PCB is also formed as a square ring, and has a smaller opening for receiving a die. The back face of the die is mounted to the heat sink. The exposed front face of the die is wire bonded to inner ends of conductive traces on the exposed face of the lower PCB. The outer ends of the traces are electrically connected to the leadframe leads by plated-through vias extending through the two PCBs. The plated-through vias additionally secure the sandwich structure together. Plastic molding compound is injection/transfer molded over the front face of the die and the bond wires, forming a partially-molded package. In another embodiment, the upper PCB is a solid planar element, and is not provided with an opening for a heat sink. The back face of the die is mounted to the inside surface of the upper PCB.

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First Claim