Flip Chip Metallurgies for Lead-Free Solders

1998 ◽  
Vol 515 ◽  
Author(s):  
T. M. Korhonen ◽  
S. J. Hong ◽  
M. A. Korhonen ◽  
C.-Y. LI
Keyword(s):  
Flip Chip ◽  
Lead Free ◽  
Weak Interface ◽  
Under Bump Metallization ◽  
Adhesion Layer ◽  
Edx Analysis ◽  
Underbump Metallization ◽  
Quality And Reliability ◽  
Lead Free Solders ◽  
Made In

ABSTRACTThe most commonly used lead-free solders contain large amounts of tin, which makes them incompatible with the conventional Cu-based underbump metallization (UBM) schemes. The tin in the solder reacts with the copper layer of the UBM, depleting the UBM of copper and causing loss of adhesion and a weak interface. Use of new under bump metallization schemes with Ni or CuNi alloys as the solderable layer were investigated in this study. Instead of Cr, a Tibased adhesion layer was used to decrease the amount of stress in the CuNi layer. Flip chip solder joints were made in which three Sn-Bi-Ag based lead-free solders were reflowed to several UBM pads of different compositions. The resulting interfacial microstructures were examined by SEM/EDX analysis of cross-sectioned samples. The joints were also mechanically tested in fatigue and shear to assess the quality and reliability of the interface.

scholarly journals Thermal Fatigue Behavior of Flip-chip Joints with Lead-free Solders

2001 ◽  
Vol 42 (5) ◽  
pp. 790-793 ◽  
Author(s):  
Ikuo Shohji ◽  
Fuminari Mori ◽  
Kojiro F. Kobayashi
Keyword(s):  
Thermal Fatigue ◽  
Flip Chip ◽  
Fatigue Behavior ◽  
Lead Free ◽  
Thermal Fatigue Behavior ◽  
Lead Free Solders

Advances in Soldering Technology

2004 ◽  
pp. 189-242
Keyword(s):  
Rare Earth ◽  
Flip Chip ◽  
Acoustic Microscopy ◽  
Lead Free ◽  
Scanning Acoustic Microscopy ◽  
Calibration Standards ◽  
Evaluation Procedures ◽  
Fine Focus ◽  
Soldering Technology ◽  
Lead Free Solders

Abstract This chapter presents several materials and processes related to soldering technology. It first provides information on lead-free solders. This is followed by sections devoted to flip-chip processes, diffusion soldering, and modeling. Scanning acoustic microscopy and fine-focus x-ray techniques are also included. The chapter then describes several evaluation procedures and tests developed to measure solderability. Reference is also made to the production of calibration standards of solderability. The chapter also describes the characteristics of reinforced solders and amalgams as solders and the strategies to boost the strength of solders. Further, the chapter considers methods for quantifying the mechanical integrity of joints and predicting their dimensional stability under specified environmental conditions. It discusses the effects of rare earth elements on the properties of solders. The chapter concludes with information on advanced joint characterization techniques.

Evaluation of Cu-bumps with lead-free solders for flip-chip package applications

2009 ◽  
Vol 86 (12) ◽  
pp. 2392-2395 ◽  
Author(s):  
Kung-Liang Lin ◽  
Edward-Yi Chang ◽  
Lin-Chi Shih
Keyword(s):  
Flip Chip ◽  
Lead Free ◽  
Lead Free Solders

Under Bump Metallization Development for Eutectic Pb-Sn Solders

1998 ◽  
Vol 515 ◽  
Author(s):  
S. J. Hong ◽  
T. M. Korhonen ◽  
M. A. Korhonen ◽  
C.-Y. LI
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Flip Chip ◽  
Electronics Packaging ◽  
Experimental Result ◽  
Under Bump Metallization ◽  
Shear Testing ◽  
Adhesion Layer ◽  
Solder Balls ◽  
Scanning Electron

ABSTRACTDue to its advantage in number of I/Os over other interconnection method, flip chip interconnection technology plays a key role in today's electronics packaging. Good understanding of interfacial reactions between the solder balls and under bump metallizations (UBM) is crucial in producing sound and reliable solder joints. In the present paper, several new under bump metallization (UBM) schemes using Ni or CuNi alloys as solderable layer are investigated. Cr or Ti is used as the adhesion layer. Test joint are made by reflowing eutectic Pb-Sn solder balls on UBMs and through the use of scanning electron microscopy (SEM) and micromechanical shear testing, the reliability of the UBM scheme is determined. Experimental result shows that some of the new schemes, featuring CuNi wettable layer with Cr or Ti adhesion layer produce reliable joints.

Under Bump Metallization Development For High Sn Solders

1997 ◽  
Vol 505 ◽  
Author(s):  
T. M. Korhonen ◽  
S. J. Hong ◽  
P. Su ◽  
C. Zhou ◽  
M. A. Korhonen ◽  
...  
Keyword(s):  
Flip Chip ◽  
Silicon Wafers ◽  
Under Bump Metallization ◽  
Shear Tests ◽  
Adhesion Layer ◽  
Solder Balls ◽  
Sputter Deposited ◽  
Pure Cu ◽  
Solder Interface ◽  
Intermetallic Layers

ABSTRACTSeveral under bump metallisation (UBM) schemes using Ni or CuNi alloys as the solderable layer were investigated. Cr or Ti was used as the adhesion layer. The UBM pads of different compositions were sputter deposited on silicon wafers and patterned using standard photolithographic processes. Eutectic Sn-Pb solder balls were reflowed on top of the pads. The resulting interfacial microstructures were examined by SEMIEDX analysis of cross-sectioned samples. The integrity of the UBMIsolder interface was characterized by micromechanical shear testing of flip chip test samples. Growth of intermetallic layers was found to be significantly slower in Ni and CuNi schemes compared to pure Cu. The joints on Ni and CuNi had also a better adhesion at the UBM/solder interface, and in the shear tests the fracture occurred through the solder

Fine pitch stencil printing of Sn/Pb and lead free solders for flip chip technology

1998 ◽  
Vol 21 (1) ◽  
pp. 41-50 ◽  
Author(s):  
J. Kloeser ◽  
K. Heinricht ◽  
K. Kutzner ◽  
E. Jung ◽  
A. Ostmann ◽  
...  
Keyword(s):  
Flip Chip ◽  
Lead Free ◽  
Stencil Printing ◽  
Chip Technology ◽  
Fine Pitch ◽  
Lead Free Solders
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