Semiconductor device manufacturing: process – Packaging or treatment of packaged semiconductor – Making plural separate devices
Reexamination Certificate
2006-05-23
2008-07-29
Tran, Thien F (Department: 2811)
Semiconductor device manufacturing: process
Packaging or treatment of packaged semiconductor
Making plural separate devices
C438S112000, C438S121000
Reexamination Certificate
active
07405106
ABSTRACT:
A QFN package with improved joint solder thickness for improved second level attachment fatigue life. The copper leadframe of a QFN chip carrier is provided with rounded protrusions in both the chip attach pad region and the surrounding lead regions before second level attachment. The rounded stand-off protrusions are formed from the copper itself of the copper of the leadframe. This may be achieved by punching dimples into one surface of the copper plate of the leadframe before plating to form protrusions on the opposing surface. This method of forming the rounded protrusions simplifies the process of forming stand-offs. The protrusions provide a structure that increases wetting area and allows the use of a larger quantity of solder for increased solder joint thickness and better die paddle solder joint area coverage. As a result of the increased solder joint thickness, second level fatigue life is significantly improved. As a result of the improved die paddle solder joint area coverage, improved thermal performance of the chip carrier is also significantly improved.
REFERENCES:
patent: 5808354 (1998-09-01), Lee et al.
patent: 5920116 (1999-07-01), Umehara et al.
patent: 6621152 (2003-09-01), Choi et al.
patent: 6861734 (2005-03-01), Minamio et al.
patent: 6882057 (2005-04-01), Hsu
patent: 6897550 (2005-05-01), Zwenger et al.
patent: 7122406 (2006-10-01), Yilmaz et al.
patent: 2003/0006055 (2003-01-01), Chien-Hung et al.
patent: 2003/0178708 (2003-09-01), Minamio et al.
Maloney John J.
Smith Robert M.
Wilson Charles H.
International Business Machines - Corporation
Jordan John A.
Steinberg William H.
Tran Thien F
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