Comment on “Effect of current crowding on vacancy diffusion and void formation in electromigration” [Appl. Phys. Lett. 76, 988 (2000)]

2001 ◽  
Vol 79 (7) ◽  
pp. 1061-1062 ◽  
Author(s):  
J. R. Lloyd
Keyword(s):  
Void Formation ◽  
Vacancy Diffusion ◽  
Current Crowding

Effect of current crowding on vacancy diffusion and void formation in electromigration

2000 ◽  
Vol 76 (8) ◽  
pp. 988-990 ◽  
Author(s):  
K. N. Tu ◽  
C. C. Yeh ◽  
C. Y. Liu ◽  
Chih Chen
Keyword(s):  
Void Formation ◽  
Vacancy Diffusion ◽  
Current Crowding

A study on the effects of electrical and thermal stresses on void formation and migration lifetime of Sn3.0Ag0.5Cu solder joints

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Yanruoyue Li ◽  
Guicui Fu ◽  
Bo Wan ◽  
Zhaoxi Wu ◽  
Xiaojun Yan ◽  
...  
Keyword(s):  
Solder Joint ◽  
Thermal Stresses ◽  
Solder Joints ◽  
Void Formation ◽  
Model Parameters ◽  
Time To Failure ◽  
Current Crowding ◽  
Theoretical Derivation ◽  
Content Type ◽  
And Migration

Purpose The purpose of this study is to investigate the effect of electrical and thermal stresses on the void formation of the Sn3.0Ag0.5Cu (SAC305) lead-free ball grid array (BGA) solder joints and to propose a modified mean-time-to-failure (MTTF) equation when joints are subjected to coupling stress. Design/methodology/approach The samples of the BGA package were subjected to a migration test at different currents and temperatures. Voltage variation was recorded for analysis. Scanning electron microscope and electron back-scattered diffraction were applied to achieve the micromorphological observations. Additionally, the experimental and simulation results were combined to fit the modified model parameters. Findings Voids appeared at the corner of the cathode. The resistance of the daisy chain increased. Two stages of resistance variation were confirmed. The crystal lattice orientation rotated and became consistent and ordered. Electrical and thermal stresses had an impact on the void formation. As the current density and temperature increased, the void increased. The lifetime of the solder joint decreased as the electrical and thermal stresses increased. A modified MTTF model was proposed and its parameters were confirmed by theoretical derivation and test data fitting. Originality/value This study focuses on the effects of coupling stress on the void formation of the SAC305 BGA solder joint. The microstructure and macroscopic performance were studied to identify the effects of different stresses with the use of a variety of analytical methods. The modified MTTF model was constructed for application to SAC305 BGA solder joints. It was found suitable for larger current densities and larger influences of Joule heating and for the welding ball structure with current crowding.

The Simulation and Analysis of Current Crowding and Joule Heat in Flip Chip Solder Bumps

2015 ◽  
Vol 645-646 ◽  
pp. 319-324
Author(s):  
Pei Sheng Liu ◽  
Long Long Yang ◽  
Jin Xin Hang ◽  
Ying Lu
Keyword(s):  
Current Density ◽  
Flip Chip ◽  
Solder Bump ◽  
Void Formation ◽  
Great Influence ◽  
Joule Heat ◽  
Time To Failure ◽  
Current Crowding ◽  
Chip Technology ◽  
Reliability Issue

Electro-migration has become a critical reliability issue for high density solder joints in flip chip technology, especially for current crowding and joule heat. Electro-migration force and mean time to failure of flip chip are introduced in this paper. This study employs two-dimensional simulation to investigate the distribution of current density and Joule heating in the flip chip joint. It is found that current crowding and Joule heat effect are very serious in the solder bump. The Joule heat may play important role in the void formation and thermo-migration in solder bump. And the factors that impact the distribution of current density and Joule heat are studied. The results show that the thickness of Al and UBM has great influence on the distribution of current density and Joule heat.

Electromigration Performance of WLPs with Standard and Polymer Core Balls

2010 ◽  
Vol 2010 (DPC) ◽  
pp. 002361-002392
Author(s):  
L. Nguyen ◽  
H. Nguyen ◽  
A. Prabhu
Keyword(s):  
Failure Modes ◽  
Void Formation ◽  
Solid Polymer ◽  
Current Crowding ◽  
Wafer Level ◽  
San Jose ◽  
Snagcu Solder ◽  
Wafer Level Packaging ◽  
Solder Balls ◽  
Board Level

This talk will compare the electromigration performance of wafer level packages having standard SnAgCu solder with those having solder balls with polymer cores. Information on package construction, process, and board level reliability of packages having balls with polymer cores was presented earlier (2009 International Wafer Level Packaging Conference, San Jose, CA). In the new ball variation, the structure is made of a large solid polymer core, which is plated with a thin layer of copper and covered with a layer of SnAg. The polymer core within the solder ball ensures that the standoff height remains constant during board assembly, and acts as a stress absorption layer between the Si and the PCB during any thermal excursion and drop testing. Such characteristics allow extension of the wafer level package from small pin count (~30 I/O) to higher pin count (100+ I/O) without the need for redistribution layers. For electromigration, bump resistances were monitored continuously at different current densities and temperatures for the two package types. Equivalent performance was obtained. Similar failure modes were observed in both cases, with pancake-like void formation growing outward from the pad corners due to current crowding. Equivalent performance was obtained, with both packages exhibiting MTTF of 1200 hrs at 150C, and 550 hrs at 165C. Application to a modified Black's equation to predict MTTF and account for current crowding, heating, and stress will also be discussed.

Numerical Methods for Analysis of Charged Vacancy Diffusion in Dielectric Solids

2006 ◽  
Author(s):  
John D. Clayton ◽  
Peter W. Chung ◽  
Michael A. Greenfield ◽  
WIlliam D. Nothwang
Keyword(s):  
Numerical Methods ◽  
Vacancy Diffusion ◽  
Dielectric Solids

Longitudinal Current Crowding as Power Limit in High Power 975 nm Diode Lasers

2020 ◽  
Author(s):  
R. B. Swertfeger ◽  
S. K. Patra ◽  
R. J. Deri ◽  
M. C. Boisselle ◽  
D. L. Pope ◽  
...  
Keyword(s):  
High Power ◽  
Diode Lasers ◽  
Current Crowding ◽  
Longitudinal Current ◽  
Power Limit

Statistical study of vacancy diffusion in TiC and TaC

2020 ◽  
Vol 4 (9) ◽  
Author(s):  
Xiaochuan Tang ◽  
Rofiques Salehin ◽  
Gregory B. Thompson ◽  
Christopher R. Weinberger
Keyword(s):  
Statistical Study ◽  
Vacancy Diffusion
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