Study of 15µm pitch solder microbumps for 3D IC integration

Developments of ultra fine pitch and high density solder microbumps and assembly process for low cost 3D stacking technologies are discussed in this paper. The solder microbumps developed in this work consist of Cu and Sn, which are electroplated in sequential with total thickness of 10 mum; The und...

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Bibliographic Details
Main Authors: Aibin Yu, Lau, J.H., Soon Wee Ho, Kumar, A., Wai Yin Hnin, Da-Quan Yu, Ming Ching Jong, Kripesh, V., Pinjala, D., Dim-Lee Kwong
Format: Conference Proceeding
Language:eng ; jpn
Subjects:
Assembly
Costs
Flip chip
Gold
Nickel
Stacking
Temperature
Three-dimensional integrated circuits
Tin
Wafer bonding
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Summary:Developments of ultra fine pitch and high density solder microbumps and assembly process for low cost 3D stacking technologies are discussed in this paper. The solder microbumps developed in this work consist of Cu and Sn, which are electroplated in sequential with total thickness of 10 mum; The under bump metallurgy (UBM) pads used here is electroless plated nickel and immersion gold (ENIG) with thickness of 2 mum. Accordingly, joining of the two Si chips can be conducted by joining CuSn solder microbumps to ENIG UBM pads or CuSn solder microbumps to CuSn solder microbumps. The first joining can only be done with chip to chip assembly whereas the second joining has the potential for chip to wafer assembly. Assembly of the Si chips is conducted with the FC150 flip chip bonder at different temperatures, times, and pressures and the optimized bonding conditions are obtained. After assembly, underfill process is carried out to fill the gap and a void free underfilling is achieved using an underfill material with fine filler size.
ISSN:0569-5503
2377-5726
DOI:10.1109/ECTC.2009.5073988