| 摘要 |
A dambar-less leadframe (102) is sandwiched between two printed circuit boards (PCBs) (104, 106). The PCBs form a major portion of the package body, and isolate the leadframe leads (108) from plastic molding compound. In one embodiment, an upper PCB (substrate) (104) is formed as a square ring, having an opening (130) containing a heat sink (150). A lower PCB (106) is also formed as a square ring, and has a smaller opening (140) for receiving a die (120). The back face (120a) of the die (120) is mounted to the heat sink (150). The exposed front face (120b) of the die (120) is wire bonded to inner ends (138a) of conductive traces (138) on the exposed face of the lower PCB (106). The outer ends (138b) of the traces (138) are electrically connected to the leadframe leads (108) by plated-through vias (132, 142) extending through the two PCBs (104, 106). The plated-through vias additionally secure the sandwich structure together. Plastic molding compound (170) is injection/transfer molded over the front face (120b) of the die (120) and the bond wires (160), 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. <IMAGE> |
