Browse Prior Art Database

Directly Attached Integrated Circuit Lead Frame

IP.com Disclosure Number: IPCOM000077214D
Original Publication Date: 1972-Jun-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

DeBoskey, WR: AUTHOR

Abstract

A lead frame is directly attached to integrated circuit chips by solder reflow joints. Thermal expansion mismatch between the chip and lead frame is handled by shaping of the lead frame terminals. The direct attachment eliminates the need for precise chip preplacement as required in other dual in-line packages. Chip testing can be accomplished before encapsulation.

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Directly Attached Integrated Circuit Lead Frame

A lead frame is directly attached to integrated circuit chips by solder reflow joints. Thermal expansion mismatch between the chip and lead frame is handled by shaping of the lead frame terminals. The direct attachment eliminates the need for precise chip preplacement as required in other dual in-line packages. Chip testing can be accomplished before encapsulation.

A lead frame 10 is disposed between clamshell members 12' and 12''. The members 12' and 12'' are of molded plastic material. The shell 12' includes grooves to accommodate the lead frame terminals 14. Each terminal comprises a copper beam approximately 0.7 mil thick and includes two 180 Degrees curves encompassing about 13 mils of length. The lead frame also includes fingers 16 for board/card soldering. An integrated circuit device 18 is backside mounted to a metal heat sink 20. The device may be mounted by conductive adhesive or solderable material. Solder pads 22 are incorporated in the device 18. The terminals are joined to the members 14 by solder-reflow processes. The members 16 permit testing of the device and connections prior to encapsulation, which joins the clamshell members 12' and 12'' together and to the substrate 20. An epoxy plastic may be employed to interconnect the substrate and clamshell members. The S-shaped terminals 14 accommodate any differential thermal expansion between the chip and the lead frame. The large line length contact bet...