Lead-Free and PbSn Bump Electromigration Testing

2005 ◽  
Author(s):  
Stephen Gee ◽  
Nikhil Kelkar ◽  
Joanne Huang ◽  
King-Ning Tu
Keyword(s):  
Cross Sections ◽  
Current Density ◽  
Critical Issue ◽  
Electronics Industry ◽  
Limiting Factor ◽  
Time To Failure ◽  
Solder Bumps ◽  
Free Solder ◽  
Mean Time ◽  
Eutectic Snpb

As the electronics industry continues to push for miniaturization, several reliability factors become vital issues. The demand for a high population of smaller and smaller solder bumps, while also increasing the current, have resulted in a significant increase in the current density. As outlined in the International Technology of Roadmap for Semiconductors (ITRS), this trend makes electromigration the limiting factor in high density packages. The heightened current density and correspondingly elevated operating temperatures are a critical issue in reliability since these factors facilitate the effects of electromigration. Therefore, as bump sizes continue to decrease, the study of electromigration reliability becomes crucial in order to understand and possibly prevent the causes of failure. A systematic study of electromigration in eutectic SnPb and Pb-free solder bumps was conducted in order to characterize the reliability of the Micro SMD package family. The testing includes both eutectic 63Sn-37Pb and 95.5Sn4.0Ag-0.5Cu solder bumps on an Al/Ni(V)/Cu under-bump-metallization. Mean-time-to-failure results are compared to Black’s Equation and cross-sections of the solder bumps are shown to analyze the mechanisms that led to failure.

Effect of Bump Shape on Current Density and Temperature Distributions in Solder Bump Joints under Electromigration

2012 ◽  
Vol 569 ◽  
pp. 82-87
Author(s):  
Yi Li ◽  
Xiu Chen Zhao ◽  
Ying Liu ◽  
Hong Li
Keyword(s):  
Current Density ◽  
Solder Bump ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Time To Failure ◽  
Element Analysis ◽  
Temperature Distributions ◽  
Maximum Current ◽  
Mean Time ◽  
Waist Radius

Three dimensional thermo-electrical finite element analysis was employed to simulate the current density and temperature distributions for solder bump joints with different bump shapes. Mean-time-to-failure (MTTF) of electromigration was discussed. It was found that as the bump volume increased from hourglass bump to barrel bump, the maximum current density increased but the maximum temperature decreased. Hourglass bump with waist radius of 240 μm has the longest MTTF.

Measurement of electromigration parameters of lead-free SnAg3.5 solder using U-groove lines

2005 ◽  
Vol 20 (10) ◽  
pp. 2831-2837 ◽  
Author(s):  
Ying-Chao Hsu ◽  
De-Chung Chen ◽  
P.C. Liu ◽  
Chih Chen
Keyword(s):  
Threshold Current ◽  
Lead Free ◽  
Time To Failure ◽  
Force Microscopy ◽  
Temperature Range ◽  
Atomic Force ◽  
Solder Bumps ◽  
Current Densities ◽  
Free Solder ◽  
Current Carrying Capability

Measurement of electromigration parameters in the lead-free solder SnAg3.5 was carried out by utilizing U-groove solder lines and atomic force microscopy in the temperature range of 100–150 °C. The drift velocity was measured, and the threshold current densities of the SnAg3.5 solder were estimated to be 4.4 × 104 A/cm2 at 100 °C, 3.3 × 104 A/cm2 at 125 °C, and 5.7 × 103 A/cm2 at 150 °C. These values represent the maximum current densities that the SnAg3.5 solder can carry without electromigration damage at the three stressing temperatures. The critical products for the SnAg3.5 solder were estimated to be 462 A/cm at 100 °C, 346 A/cm at 125 °C, and 60 A/cm at 150 °C. In addition, the electromigration activation energy was determined to be 0.55 eV in the temperature range of 100–150 °C. These values are very fundamental for current carrying capability and mean-time-to-failure measurement for solder bumps. This technique enables the direct measurement of electromigration parameters of solder materials.

Wafer Bumping and Characterizations of Fine-Pitch Lead-Free Solder Microbumps on 12” (300mm) wafer for 3D IC Integration

2011 ◽  
Vol 2011 (1) ◽  
pp. 000650-000656
Author(s):  
J. H. Lau ◽  
P-J Tzeng ◽  
C-K Lee ◽  
C-J Zhan ◽  
M-J Dai ◽  
...  
Keyword(s):  
Cross Sections ◽  
Lead Free ◽  
Lead Free Solder ◽  
Sem Images ◽  
3D Ic ◽  
Fine Pitch ◽  
Solder Bumps ◽  
Before And After ◽  
Free Solder

In this study, the wafer bumping and characterization of fine-pitch lead-free solder microbumps on 300mm wafer for 3D IC integration are investigated. Emphasis is placed on the Cu-plating solutions (conformal and bottom-up). Also, the amount of Cu and solder (Sn) volumes is examined. Furthermore, characterizations such as shearing test and aging of the microbumps are provided and cross sections/SEM images of the microbumps before and after test are discussed. Finally, the process windows of applying the conventional electroplating wafer bumping method of the ordinary solder bumps to the microbumps are also presented.

Microstructure and Lifetime Study of Al/Y Films

1998 ◽  
Vol 514 ◽  
Author(s):  
L. Vedula ◽  
V. Pillai ◽  
V. S. Nimmagadda ◽  
R. Singh ◽  
K. F. Poole ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetron Sputtering ◽  
Current Density ◽  
Size Variation ◽  
Residual Resistivity ◽  
Time To Failure ◽  
Furnace Annealing ◽  
Mean Time ◽  
A Current ◽  
Si Wafer

ABSTRACTThin Al films alloyed with three different compositions (0.1%, 1%, 5% by weight) of Yttrium were deposited by D.C. Magnetron Sputtering onto oxidized Si wafer substrates. The samples were furnace annealed at 425 °C for 30 minutes. Resistivity measured for the as-deposited and annealed Al(0. lwt% Y) were 3.07 and 2.57+/−0.25 μΩcm respectively. Al(0. lwt% Y) was also annealed by furnace annealing (FA), rapid thermal annealing (RTA) and rapid photothermal annealing (RPA). RPA gave a residual resistivity of 2.67μΩcm in 5 minutes and at a temperature of 350 C for Al(0. lwt% Y). Mean time to failure for AI(0. lwt% Y) samples at a current density of 3.2+/−0.5×106A/cm2 at 30 C was 50 hours. TEM results showed grain size variation from 0.5 to 2 μm.

Intermetallic Effects of Electroplated Lead-Free Solder Bumps Using a Novel Single Chamber Electroplating Process for Large Diameter Wafers

2007 ◽  
Author(s):  
J. Teye Brown ◽  
Ajay M. Popat ◽  
Chad B. O’Neal ◽  
Yixiang Xie
Keyword(s):  
Cross Sections ◽  
Visual Inspection ◽  
Large Diameter ◽  
Lead Free Solder ◽  
Elemental Mapping ◽  
Single Chamber ◽  
Metal Plating ◽  
Solder Bumps ◽  
Free Solder ◽  
Electroplating Process

In this study solder bumps of various alloys and less than 100 microns in diameter were electroplated using a novel single chamber electroplating process in which the plating baths are exchanged between the different metal plating layers. This equipment is new to the manufacturing arena. The reflow profile and process was then optimized for the various alloys such as SnAg, and electroplated layered SnPb, and PbSn 95/5%, with PbSn 95/5% being the control leaded solder for comparison. Various fluxes were also used during the reflow of these bumps. The solder bumps were reflowed on a conduction reflow oven in a nitrogen environment such that the temperature profile could be carefully controlled. The bumps were analyzed by examining the bump diameter and height uniformity, surface quality, and elemental composition and distribution inside the bumps. These analyses were done by visual inspection by optical microscopy, scanning electron microscopy, and electron dispersive spectroscopy (EDS). The wafers were diced near a row of solder bumps, then podded and polished using a metallographic polishing system to the center of solder bumps. These bump cross-sections were then examined by EDS to perform elemental mapping of the alloy constituents.

Tensile fracture behaviors of solid-state-annealed eutectic SnPb and lead-free solder flip chip bumps

2004 ◽  
Vol 19 (6) ◽  
pp. 1826-1834 ◽  
Author(s):  
Jin-Wook Jang ◽  
Ananda P. De Silva ◽  
Jong-Kai Lin ◽  
Darrel R. Frear
Keyword(s):  
Solid State ◽  
Fracture Behavior ◽  
Flip Chip ◽  
Interfacial Fracture ◽  
Bulk Solder ◽  
Tensile Fracture ◽  
Solder Bumps ◽  
Snag Solder ◽  
Free Solder ◽  
Eutectic Snpb

The tensile fracture behavior for solid-state-annealed eutectic SnPb and lead-free solder flip chip bumps was examined. The annealing temperatures were in the range of 125–170 °C for 500 h. Prior to solid state annealing, the eutectic Sn–37Pb (SnPb) and Sn–0.7Cu (SnCu) solders showed fracture through the bulk solder. Brittle interfacial fracture occurred in the Sn–3.5Ag (SnAg) solder. After solid-state annealing, the fracture behavior changed dramatically. For eutectic SnPb solder, the fracture modes gradually changed from cohesive solder failure to interfacial fracture with increasing annealing temperature. The fracture mode of the SnCu solder showed greater change than the SnPb and SnCu solders. After annealing at 125 °C, the SnAg solder had a ductile taffy pull fracture, but an increase in temperature resulted in brittle interfacial fracture again. The SnCu solder maintained the same ductile taffy pull mode up to170 °C annealing, independent of the under bump metallization (UBM) type. Microstructure analysis showed that the interfacial fracture of the SnPb and SnAg solder bumps was ascribed to Pb-rich layer formation and Ag embrittlement at the interface, respectively. The bulk solder fracture of SnAg annealed at 125 °C appeared to be a transient phenomenon due to the abrupt breakdown of the hard lamella structure. The eutectic SnCu solder bumps had no significant change in the interfacial structure, except for interfacial intermetallic growth.

Electromigration in Gold Line of GaAs IC

1998 ◽  
Author(s):  
A. Ohta ◽  
K. Yajima ◽  
N. Higashisaka ◽  
T. Heima ◽  
T. Hisaka ◽  
...  
Keyword(s):  
Activation Energy ◽  
Current Density ◽  
Electron Flow ◽  
Failure Mechanisms ◽  
Cathode Side ◽  
Time To Failure ◽  
Dc Bias ◽  
Molybdenum Surfaces ◽  
Mean Time ◽  
Test Current

Abstract This paper describes voids in a gold line, which is a new failure mechanisms of GaAs IC using gold line as interconnection. We have found voids in both first and second metal under DC bias test, current density of 0.67 to 1.27 106 A/cm2 in high temperature range of 230 °C to 260 °C. We have observed carefully the movement of voids during the test and found that voids moved toward a cathode, in the opposite direction of electron flow. The velocity of voids increased with the current density almost proportionally. The moving mechanisms of a void can be explained by assuming that gold atoms move toward an anode by electromigration. The activation energy of the void velocity was 0.84 eV at the cathode side. This was nearly equal to 0.6 eV - 0.9 eV reported on the velocity of the gold island on molybdenum surfaces [1]. The GaAs IC failed at the almost same time as the voids appeared. The activation energy of mean time to failure of the IC was 0.89 eV, which was nearly equal to that of the void velocity at the cathode edge of 0.84 eV.

scholarly journals Surveillance System in Smart Cities: A Dependability Evaluation Based on Stochastic Models

Electronics ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 876
Author(s):  
Igor Gonçalves ◽  
Laécio Rodrigues ◽  
Francisco Airton Silva ◽  
Tuan Anh Nguyen ◽  
Dugki Min ◽  
...  
Keyword(s):  
Surveillance System ◽  
Smart Cities ◽  
Heterogeneous Data ◽  
Time To Failure ◽  
Video Streams ◽  
Dependability Evaluation ◽  
The Mean ◽  
Mean Time ◽  
The Internet Of Things

Surveillance monitoring systems are highly necessary, aiming to prevent many social problems in smart cities. The internet of things (IoT) nowadays offers a variety of technologies to capture and process massive and heterogeneous data. Due to the fact that (i) advanced analyses of video streams are performed on powerful recording devices; while (ii) surveillance monitoring services require high availability levels in the way that the service must remain connected, for example, to a connection network that offers higher speed than conventional connections; and that (iii) the trust-worthy dependability of a surveillance system depends on various factors, it is not easy to identify which components/devices in a system architecture have the most impact on the dependability for a specific surveillance system in smart cities. In this paper, we developed stochastic Petri net models for a surveillance monitoring system with regard to varying several parameters to obtain the highest dependability. Two main metrics of interest in the dependability of a surveillance system including reliability and availability were analyzed in a comprehensive manner. The analysis results show that the variation in the number of long-term evolution (LTE)-based stations contributes to a number of nines (#9s) increase in availability. The obtained results show that the variation of the mean time to failure (MTTF) of surveillance cameras exposes a high impact on the reliability of the system. The findings of this work have the potential of assisting system architects in planning more optimized systems in this field based on the proposed models.

On classes of life distributions based on the mean time to failure function

2021 ◽  
Vol 58 (2) ◽  
pp. 289-313
Author(s):  
Ruhul Ali Khan ◽  
Dhrubasish Bhattacharyya ◽  
Murari Mitra
Keyword(s):  
Damage Model ◽  
Replacement Policy ◽  
Time To Failure ◽  
Mean Time To Failure ◽  
Moment Convergence ◽  
Life Distributions ◽  
Cumulative Damage Model ◽  
The Mean ◽  
Age Replacement ◽  
Mean Time

AbstractThe performance and effectiveness of an age replacement policy can be assessed by its mean time to failure (MTTF) function. We develop shock model theory in different scenarios for classes of life distributions based on the MTTF function where the probabilities $\bar{P}_k$ of surviving the first k shocks are assumed to have discrete DMTTF, IMTTF and IDMTTF properties. The cumulative damage model of A-Hameed and Proschan [1] is studied in this context and analogous results are established. Weak convergence and moment convergence issues within the IDMTTF class of life distributions are explored. The preservation of the IDMTTF property under some basic reliability operations is also investigated. Finally we show that the intersection of IDMRL and IDMTTF classes contains the BFR family and establish results outlining the positions of various non-monotonic ageing classes in the hierarchy.

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