Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2007-08-30
2009-12-08
Dang, Trung (Department: 2892)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S615000, C257SE21508
Reexamination Certificate
active
07629246
ABSTRACT:
A Micro SMDxt package is provided that configured for mounting to a circuit board. The SMDxt package includes a silicon-based IC having an array of contact pads on one side of thereof, and a die electrically attached to the silicon-based IC. A plurality of solder balls is included, each of which has a polymeric core surrounded by a metallic shell that in turn is surrounded by a layer of solder material. Further, each solder ball is positioned in contact with a corresponding contact pad of the package. An intertwined intermetallic fusion layer is formed through the fusion between material components of the contact pads and the solder material, via heat treatment. The intermetallic fusion extends between and from an outer surface of the metallic shell of each solder to an outer surface of a corresponding contact pad to form a high strength intermetallic solder joint therebetween.
REFERENCES:
patent: 2002/0171143 (2002-11-01), Kinsman
patent: 2004/0177997 (2004-09-01), Hata et al.
patent: 2008/0169539 (2008-07-01), Fang et al.
patent: 2000228455 (2000-08-01), None
Pang, et al.,Intermetallic Growth Studies on Sn-Ag-Cu Lead-Free Solder Joints, Journal of Electronic Materials, vol. 33, No. 10, 2004.
Nguyen Hau
Patwardhan Viraj
Beyer Law Group LLP
Dang Trung
National Semiconductor Corporation
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