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|Type of Document
||A Study of the Influence of Plasma Cleaning Process on Mechanical and Electrical Characteristics of Gold, Aluminum and Platinum Pads|
|Date of Defense
||To improve the wire bondability, interfacial adhesion and popcorn cracking resistance in the packaging processing of IC and MEMS chips, this thesis utilized oxygen and helium plasmas to modify and clean the surface of metal pads. The influences of the plasma cleaning time, metal pad materials and wire bonding time/temperature/power on the strength of wire bonding were investigated.|
Two different wire materials (Al wire with 32 μm in diameter and Au wire with 25 μm in diameter) were bonded on the surface of Al, Au and Pt metal pads using a commercial ultrasonic wire bonder (SPB-U688), respectively. The pull strength detection of the implemented micro joints is characterized by an accurate pull strength testing system (Dage SERIES-4000).
Based on hundred measurement results, this research has three conclusions described as follows. (I) The pull strength of Au pad is higher than that of Al and Pt pads no matter with the plasma cleaning process or not. The maximum pull strength (12.286 g) can be achieved as the surface of Au pad was modified by the helium plasma for 180 seconds. (II) Helium plasma cleaned wafer can obtain larger improvement of pull strength than that of the oxygen plasma under the same plasma time. However, this result can not be concluded in Al and Pt pads. (III) The optimized wire bonding time/power of the Au, Al and Pt pads are 0.07 s/2.1, 0.05 s/0.6 W and 0.03 s/2.7 W, respectively.
||Yu-Cheng Lin - chair|
Wei-Leun Fang - co-chair
Jin-Chern Chiou - co-chair
Ruey-Shing Huang - co-chair
I-Yu Huang - advisor
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|Date of Submission