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|Low Cost Ownership of WLCSP Interconnection|
|Keywords: WLCSP, Double ball , Reliability|
|Ball Grid Array Package which is one of semiconductor packages is moving to WLCSP (Wafer Level Chip Size Package) because of low cost, small form factor, high electrical performance, and so on. WLCSP has a different reliability symptom from BGA because of the big difference CTEs (Coefficient of Thermal Expansion) between Organic PCB and component package. Generally large chip size is hard to meet 2nd level reliability in the WLCSP. To increase the solder joint life time, the longer solder interconnection from WLCSP to organic PCB module could be helpful, so Cu Post with single solder ball interconnection between WLCSP and organic PCB module has been introduced from many companies, but it is true that the Cu electroplating is being shown a high Cost of Ownership on 300mm wafer because Cu post plated electrically is formed with a low plating rate (max. 2um/min.). Double solder balls interconnection of WLCSP is very promising to achieve a low Cost of Ownership with a compatible solder joint reliability with printing solder paste process. In this paper, the each structured WLCSP fabrication steps are described, and the compared SJR (Solder Joint Reliability) results for both Cu post with single solder ball and double solder balls interconnection between WLCSP and organic PCB module are discussed. Based on this study, double solder balls structure of WLCSP is one of the solutions for achieving a lower cost and a longer solder joint life time.|
|Young Do Kweon, Principal Engineer
Samsung Electro-Mechanics Co. LTD.
Suwon, Gyunggi-Do 443-743 ,
Republic of Korea (South)