Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – Insulating material
Reexamination Certificate
2008-03-04
2008-03-04
Smith, Zandra V. (Department: 2822)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
Insulating material
Reexamination Certificate
active
11140351
ABSTRACT:
Semiconductor packages (100) that prevent the leaching of gold from back metal layers (118) into the solder (164) and methods for fabricating the same are provided. An exemplary method comprises providing a semiconductor wafer stack (110) including metal pads (112) and a substrate (116). An adhesion/plating layer (115) is formed on the substrate (116). A layer of gold (118) is plated on the adhesion/plating layer (115). The layer of gold is etched in a street area (124) to expose edge portions (128) of the layer of gold (118) and the adhesion/plating layer (115). A layer of barrier metal (130) is deposited to form an edge seal (129) about the exposed edge portions (128). The edge seal (129) prevents the leaching of gold from back metal layers (118) into the solder (162) when the wafer stack (110) is soldered to a leadframe (162).
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Fender, J. et al. Development of Backside Process For Use with Solder Paste Die Attach, Apr. 24, 2006 CS Mantech Conference, pp. 209-211.
Daly Terry K.
Fender Jason
Jang Jin-Wook
Thompson Vasile Romega
Freescale Semiconductor Inc.
Ingrassia Fisher & Lorenz P.C.
Patton Paul E
Smith Zandra V.
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