Invention Grant
- Patent Title: Quad flat no-lead chip carrier with standoff
- Patent Title (中): 四通扁平无引线芯片载体与对接
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Application No.: US12164152Application Date: 2008-06-30
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Publication No.: US08134225B2Publication Date: 2012-03-13
- Inventor: John J. Maloney , Robert M. Smith , Charles H. Wilson
- Applicant: John J. Maloney , Robert M. Smith , Charles H. Wilson
- Applicant Address: US NY Armonk
- Assignee: International Business Machines Corporation
- Current Assignee: International Business Machines Corporation
- Current Assignee Address: US NY Armonk
- Agent John A. Jordan
- Main IPC: H01L23/495
- IPC: H01L23/495

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.
Public/Granted literature
- US20080265396A1 QUAD FLAT NO-LEAD CHIP CARRIER WITH STANDOFF Public/Granted day:2008-10-30
Information query
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