Browse Prior Art Database

Integrated Circuit Structure Including Soldered Lead Frame

IP.com Disclosure Number: IPCOM000080168D
Original Publication Date: 1973-Nov-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Rajac, TJ: AUTHOR

Abstract

In Fig. 1, lead frame 10 is stamped or etched from a prerolled blank and stored in a reel, not shown, for distribution to an assembly location, not shown, for integrated circuit structures. The lead frame 10 includes terminal portions 12 and finger portions 14. A chip 16 includes solder balls 18 about the periphery for joining to the fingers 14. Bow like portions 20 are included in the lead frame 10 to absorb the mechanical forces generated during solder reflow cycling in joining the lead frame to the chip, and in subsequent temperature cycles experienced by the assembly.

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Integrated Circuit Structure Including Soldered Lead Frame

In Fig. 1, lead frame 10 is stamped or etched from a prerolled blank and stored in a reel, not shown, for distribution to an assembly location, not shown, for integrated circuit structures. The lead frame 10 includes terminal portions 12 and finger portions 14. A chip 16 includes solder balls 18 about the periphery for joining to the fingers 14. Bow like portions 20 are included in the lead frame 10 to absorb the mechanical forces generated during solder reflow cycling in joining the lead frame to the chip, and in subsequent temperature cycles experienced by the assembly.

In Figs. 2A and 2B, the lead frame fingers 14 include a polymer or chromium stop-off 21 to form a column-like solder pad. The construction of the solder pads "floats" the chip 16 to take up expansion mismatch between the chip and the substrate 22.

The chip 16 and lead frame 10 are joined together using a reflow soldering cycle. This assembly is delivered to an assembly point where the top 24, and bottom 22 shells are joined together over the chip/lead frame assembly. The terminals 12 are suitably bent to engage a printed-circuit card, not shown. Stand-offs 27 provide a seating plane for the structure relative to the printed-circuit card.

The members 22 and 24 may be mechanically joined using pin members 26 or the members may be joined together by a suitable adhesive.

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