Thermally Enhanced Plastic Surface Encapsulated Device
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
The present device offers improved heat dissipation by forming portions of lead frames into heat dissipating tabs for I/C chips packaged by encapsulating in plastic. Fig. 1 shows an etched lead frame segment from which electrical leads to a chip are formed. The material typically is a thin gauge (.006") copper alloy. Each segment includes a central mounting pad 10, a plurality of leads 12, four enlarged tab members 14, all surrounded by selvage 16, which selvage is trimmed after chip mounting, wire bonding, and encapsulation. As shown in Fig. 2 in longitudinal section, an I/C chip 18 is back bonded to the down set pad 10 by solder 20 or a thermally conducting adhesive. Wire leads 24 are thermosonically ball bonded from chip I/O pads 22 to the inner ends of leads 12. This configuration is then encapsulated, as shown in Fig.