Temperature and current-density distributions in flip-chip solder joints with Cu traces

2006 ◽  
Vol 35 (5) ◽  
pp. 947-953 ◽  
Author(s):  
C. Y. Hsu ◽  
D. J. Yao ◽  
S. W. Liang ◽  
Chih Chen ◽  
Everett C. C. Yeh
Keyword(s):  
Current Density ◽  
Flip Chip ◽  
Solder Joints ◽  
Density Distributions

Electromigration in Solder Joints for High Temperature Flip-Chip Application

2011 ◽  
Vol 2011 (DPC) ◽  
pp. 002481-002506
Author(s):  
Mathias Nowottnick ◽  
Andreas Fix
Keyword(s):  
High Temperature ◽  
Current Density ◽  
Flip Chip ◽  
Solder Joints ◽  
Metallographic Analysis ◽  
Solder Alloys ◽  
Directed Movement ◽  
Cross Sectional ◽  
Current Densities ◽  
And Migration

The electromigration effects in chip metallization and wire bonds are well known and detailed investigated. Current density could be extremely high because of the small size of the cross sectional area of conductors. This can cause a migration of metal atoms toward the electrical field, so current densities up to 106 A/cm2 are possible. In comparison with chip structures are the usual solder joints of flip chips relatively thick. But the homologue temperature of solder alloys, typically based on tin, is also much higher than for gold or aluminum wires. For instance a SAC solder alloy is naturally preheated up to 0.6 homologue temperature, for high temperature application with 125 °C operating temperature even more than 0.8. This means, that atoms are very agile and a directed movement needs only lower field strength. Additionally is the specific resistance of solder alloys tenfold higher than for aluminum, copper or silver. So is the self-heating of solder joints not negligible. This contribution shows the test results of flip-chip assemblies, loaded with different current densities and stored at 125 °C ambient temperature. At the end of life of a significant number of test chips, a metallographic analysis shows the causing failure effects and weak spots of assemblies. Accompanying simulations help to explain the interaction between current density and migration effects.

Electromigration Reliability With Respect to Cu Weight Contents of Sn–Ag–Cu Flip-Chip Solder Joints Under Comparatively Low Current Stressing

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Yi-Shao Lai ◽  
Ying-Ta Chiu
Keyword(s):  
Intermetallic Compound ◽  
Ambient Temperature ◽  
Current Density ◽  
Flip Chip ◽  
Solder Joints ◽  
Average Current Density ◽  
Current Stressing ◽  
Weight Content ◽  
Average Current ◽  
Better Than

This work presents electromigration reliability and patterns of Sn–3Ag–0.5Cu and Sn–3Ag–1.5Cu∕Sn–3Ag–0.5Cu composite flip-chip solder joints with Ti∕Ni(V)∕Cu under bump metallurgy (UBM), bonded on Au∕Ni∕Cu substrate pads. The solder joints were subjected to an average current density of 5kA∕cm2 under an ambient temperature of 150°C. Under the situation when electron charges flow from the UBM toward the substrate, Sn diffuses from the Cu–Ni–Sn intermetallic compound developed around the UBM toward the UBM and eventually causes the Ni(V) layer to deform. Electromigration reliability of Sn–3Ag–1.5Cu∕Sn–3Ag–0.5Cu composite flip-chip solder joints was found to be better than that of Sn–3Ag–0.5Cu solder joints. According to the morphological observations on cross-sectioned solder joints, a failure mechanism is proposed as follows. Since the deformation of the Ni(V) layer as a result of Sn diffusion toward the UBM is considered as the dominant failure, a greater Cu weight content in the solder joints would trap more Sn in the Sn–Cu interfacial reaction and would therefore retard the diffusion of Sn toward the UBM and hence enhance the electromigration reliability.

Electromigration Induced Metal Dissolution in Flip-Chip Solder Joints

2005 ◽  
Vol 475-479 ◽  
pp. 2655-2658 ◽  
Author(s):  
Y.H. Lin ◽  
C.M. Tsai ◽  
Y.C. Hu ◽  
Y.L. Lin ◽  
J.Y. Tsai ◽  
...  
Keyword(s):  
Mass Transport ◽  
Current Density ◽  
Flip Chip ◽  
Solder Joints ◽  
Critical Role ◽  
Current Crowding ◽  
Metal Dissolution ◽  
Cu Metallization

The failure of flip chip solder joints through the dissolution of the Cu metallization was studied. From the location and geometry of the dissolved Cu, it can be concluded that current crowding played a critical role in the dissolution. It can also be concluded that temperature, as an experimental variable, is not less import than the current density in electromigration study. Experimentally, no evidence of mass transport due to thermomigration was observed.

Electromigration Behavior in Sn-37Pb and Sn-3.0Ag-0.5Cu Flip-Chip Solder Joints under High Current Density

2008 ◽  
Vol 38 (1) ◽  
pp. 70-77 ◽  
Author(s):  
Sang-Su Ha ◽  
Jong-Woong Kim ◽  
Jeong-Won Yoon ◽  
Sang-Ok Ha ◽  
Seung-Boo Jung
Keyword(s):  
Current Density ◽  
Flip Chip ◽  
Solder Joints ◽  
High Current Density ◽  
High Current

Failure Modes of Flip Chip Solder Joints Under High Electric Current Density

2004 ◽  
Vol 127 (2) ◽  
pp. 157-163 ◽  
Author(s):  
C. Basaran ◽  
H. Ye ◽  
D. C. Hopkins ◽  
D. Frear ◽  
J. K. Lin
Keyword(s):  
Solder Joint ◽  
Current Density ◽  
Flip Chip ◽  
Failure Modes ◽  
Solder Joints ◽  
Void Nucleation ◽  
Electrical Current ◽  
Nucleation And Growth ◽  
Joint Interface ◽  
Void Nucleation And Growth

The failure modes of flip chip solder joints under high electrical current density are studied experimentally. Three different failure modes are reported. Only one of the failure modes is caused by the combined effect of electromigration and thermomigration, where void nucleation and growth contribute to the ultimate failure of the module. The Ni under bump metallization–solder joint interface is found to be the favorite site for void nucleation and growth. The effect of pre-existing voids on the failure mechanism of a solder joint is also investigated

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