Browse Prior Art Database

Thermally Enhanced Plastic Surface Encapsulated Device

IP.com Disclosure Number: IPCOM000046819D
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Ward, WC: AUTHOR

Abstract

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.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 100% of the total text.

Page 1 of 2

Thermally Enhanced Plastic Surface Encapsulated Device

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. 3, in plastic 26 to form a package with lead wires 12 and tab members 14 extending therefrom. The tab members 14 will act as heat sinks to carry heat from the chip 18. These tabs can be secured to a board, or they can be folded onto the top of the plastic 26 and act as a support and thermal pathway to a heat sink 28 mounted thereon by solder connection, as shown in the figures.

1

Page 2 of 2

2

[This page contains 3 pictures or other non-text objects]