scholarly journals Ag3Sn Compounds Coarsening Behaviors in Micro-Joints

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2509 ◽  
Author(s):  
Ye Tian ◽  
Ning Ren ◽  
Zhihua Zhao ◽  
Fengshun Wu ◽  
Suresh Sitaraman
Keyword(s):  
Kinetic Model ◽  
Thermal Shock ◽  
Thermal Aging ◽  
Experimental Validation ◽  
Flip Chip ◽  
Ostwald Ripening ◽  
Solder Joints ◽  
Critical Role ◽  
Growth Exponent ◽  
Reliability Of Solder Joints

As solder joints are being scaled down, intermetallic compounds (IMCs) are playing an increasingly critical role in the reliability of solder joints, and thereby an in-depth understanding of IMCs microstructure evolutions in micro-joints is of great significance. This study focused on coarsening behaviors of Ag3Sn compounds in Sn-3.0Ag-0.5Cu (SAC305) micro-joints of flip chip assemblies using thermal shock (TS) tests. The results showed that the Ag3Sn compounds grew and rapidly coarsened into larger ones as TS cycles increased. Compared with such coarsening behaviors during thermal aging, TS exhibited a significantly accelerating influence. This predominant contribution is quantitatively determined to be induced by strain-enhanced aging. Moreover, based on observations for Ag3Sn microstructure evolutions during TS cycling, one particular finding showed that there are two types of coarsening modes (i.e., Ostwald ripening and Necking coalescence) co-existing in the Ag3Sn coarsening process. The corresponding evolutions mechanism was elucidated in a combination of simulative analysis and experimental validation. Furthermore, a kinetic model of the Ag3Sn coarsening was established incorporating static aging and strain-enhanced aging constant, the growth exponent (n) was calculated to be 1.70, and the predominant coarsening mode was confirmed to be the necking coalescence.

scholarly journals Effect of Trace Zn Addition on Interfacial Evolution in Sn-10Bi/Cu Solder Joints during Aging Condition

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4240
Author(s):  
Qingfeng Wang ◽  
Hong Chen ◽  
Fengjiang Wang
Keyword(s):  
Interfacial Reaction ◽  
Thermal Aging ◽  
Solder Joints ◽  
Depressing Effect ◽  
Aging Condition ◽  
Obvious Effect ◽  
Cu Substrate ◽  
Zn Addition ◽  
Reliability Of Solder Joints ◽  
Interfacial Evolution

Excessive growth of intermetallic compounds (IMCs) during service affects the reliability of solder joints, so how to suppress the growth of IMC thickness at the interface in solder joints becomes a widespread concern. In this work, the interfacial reaction between Sn-10Bi solder and Cu substrate after thermal aging was investigated. Moreover, to depress the IMC growth at the interface, trace amounts of Zn was added into the Sn-10Bi solder, and the interfacial reactions of Sn-10Bi-xZn solders (x = 0.2, 0.5) and Cu substrate after thermal aging were studied in this paper. Compounds such as Cu6(Sn, Zn)5 and Cu5Zn8 were formed at the interface after adding trace amounts of Zn. The addition of 0.2 and 0.5 wt% Zn significantly inhibited the thickness growth of IMCs and the formation of Cu3Sn IMC at the interface of Sn-10Bi-0.2Zn/Cu and Sn-10Bi-0.5Zn/Cu during thermal aging. Therefore, the addition of trace Zn had an obvious effect on the interfacial reaction of Sn-10Bi/Cu solder joint. Interestingly, the evolution of IMC thickness in Sn-10Bi-0.5Zn/Cu solder joints was completely different from that in Sn-10Bi or Sn-10Bi-0.2Zn solder joints, in which the spalling of IMCs occurred. In order to explore the mechanisms on the depressing effect from the addition of trace Zn, the activation energy Q in solder joints during aging was calculated.

Analysis of Stress Distribution in SnAgCu Solder Joint

2006 ◽  
Vol 5-6 ◽  
pp. 359-366 ◽  
Author(s):  
J. Gong ◽  
C. Liu ◽  
P.P. Conway ◽  
Vadim V. Silberschmidt
Keyword(s):  
Residual Stresses ◽  
Flip Chip ◽  
Solder Joints ◽  
Electronic Packages ◽  
Snagcu Solder ◽  
Snpb Solder ◽  
Creep Fatigue ◽  
Element Approach ◽  
Reliability Of Solder Joints ◽  
Free Material

SnAgCu solder is a promising lead-free material for interconnections in electronic packages. However, its melting temperature (490°K) is considerably higher than that of the traditional SnPb solder (456°K). At the same time, SnAgCu has much better creep resistance at high temperature. These properties may cause large residual stresses during manufacturing processes due to the mismatch of thermal properties of electronic components that can influence the reliability of solder joints in electronic packages. This paper studies the residual stresses in solder joints in a flip chip package under different cooling conditions and their influence on the subsequent cyclic test by means of a finite element approach. The results show that the initial temperature of 453°K is high enough to induce residual stresses due to manufacturing procedures. Simulations, based on traditional creep-fatigue models, demonstrate that the residual stresses affect the mechanical behaviour of solder joints in several initial thermal cycles but have little effect on their reliability.

Characteristics of Sn-2.5Ag flip chip solder joints under thermal shock test conditions

2009 ◽  
Vol 23 (2) ◽  
pp. 435-441 ◽  
Author(s):  
Kyoung Chun Yang ◽  
Seong Hyuk Lee ◽  
Jong-Min Kim ◽  
Young Ki Choi ◽  
Dave F. Farson ◽  
...  
Keyword(s):  
Thermal Shock ◽  
Flip Chip ◽  
Solder Joints ◽  
Thermal Shock Test ◽  
Shock Test ◽  
Test Conditions

Optimization of Copper Column Flip Chip Packages Incorporating a Variable Interconnect Compliance Configuration

2007 ◽  
Author(s):  
Andrew A. O. Tay ◽  
Siow Ling Ho
Keyword(s):  
Fatigue Life ◽  
Flip Chip ◽  
Solder Joints ◽  
Wafer Level ◽  
Elastic Plastic ◽  
Creep Analysis ◽  
Reliability Of Solder Joints ◽  
The Impact ◽  
Plastic Creep ◽  
Copper Column

This paper describes a parametric study of the reliability of solder joints in wafer level flip chip packages that employ copper column interconnects. In this study, the impact of the change in the compliance of the copper column interconnects on the fatigue life of the solder joints were investigated by varying the diameter of the copper column interconnects. 2-D elastic-plastic finite element analyses were carried out on packages with constant interconnect diameter as well as those with variable interconnect diameters within the same package. The effect of changing the pitch and the pad size were also studied. It was found that an effective strategy in increasing the fatigue life and hence the reliability of the solder joints is by distributing copper columns of lower compliance (greater diameter) near the center of the package and increasing the compliance of the copper columns (decreasing their diameter) towards the perimeter of the chip package. In addition, elastic-plastic-creep analysis was also performed on the packages. It was observed that the results from the elastic-plastic analysis and the elastic-plastic-creep analysis exhibit the same trend.

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.

Strategies for Improving Reliability of Solder Joints on Power Semiconductor Devices

2003 ◽  
Author(s):  
Guo-Quan Lu ◽  
Xingsheng Liu ◽  
Sihua Wen ◽  
Jesus Noel Calata ◽  
John G. Bai
Keyword(s):  
Finite Element ◽  
Solder Joint ◽  
Thermal Cycling ◽  
Flip Chip ◽  
Solder Joints ◽  
Mechanical Stresses ◽  
Flexible Substrates ◽  
Solder Joint Reliability ◽  
Joint Reliability ◽  
Reliability Of Solder Joints

There has been a significant research effort on area-array flip-chip solder joint technology in order to reduce package footprint, enhance current handling capability, and improve heat dissipation. However, there is a lingering concern over cyclic fatigue of solder alloys by thermo-mechanical stresses arising from mismatched thermal expansion coefficients of expansion among the various components of the package. In this paper, some strategies taken to improve the reliability of solder joints on power devices in single-device and multi-chip packages are presented. A strategy for improving solder joint reliability by adjusting solder joint geometry, underfilling and utilization of flexible substrates is discussed with emphasis on triple-stacked solder joints that resemble the shape of an hourglass. The hourglass shape relocates the highest inelastic strain away from the weaker interface with the chip to the bulk region of the joint while the underfill provides a load transfer from the joints. Flexible substrates can deform to relieve thermo-mechanical stresses. Thermal cycling data show significant improvements in reliability when these techniques are used. The design, testing, and finite-element analyses of an interconnection structure, termed the Dimple-Array Interconnect (DAI), for improving the solder joint reliability is also presented. In the DAI structure, a solder is used to join arrays of dimples pre-formed on a metal sheet onto the bonding pads of a device. Finite-element thermo-mechanical analyses and thermal cycling data show that the dimple-array solder joints are more fatigue-resistant than the conventional barrel-shaped solder joints in flip-chip IC packages.

Numerical Investigation on Electromigration Oriented Failure of Lead Free Solder Joints With Aging Effects

2019 ◽  
Author(s):  
Tusher Ahmed ◽  
Mohammad Motalab ◽  
Jeffrey C. Suhling
Keyword(s):  
Thermal Aging ◽  
Flip Chip ◽  
Solder Joints ◽  
Mass Diffusion ◽  
Lead Free ◽  
Small Scale ◽  
Time To Failure ◽  
Lead Free Solder ◽  
Aging Effects ◽  
Free Solder

Abstract Lead free solder materials have replaced lead based solder materials nowadays for increased environmental concern. Further miniaturization of electronic solder joints in packages has caused electromigration to dominate among all the reliability issues found in electronic packages. This current investigation deals with the review of mechanical property degradations of SAC305(Sn-96.5Ag-3.0Cu-0.5) solder materials due to thermal aging and their effects on electromigration oriented failure of small scale flip chip solder bumps. Thermal aging causes significant degradation of ultimate strength as well as elastic modulus of the SAC solder material. This degradation in stress-strain relationship plays an utterly important role in electromigration oriented mass diffusion and subsequent failure in the solder joints. This research highlights the linkage between thermal aging oriented strength degradation and its effect on electromigration oriented void propagation rate and time to failure. Structural-electric diffusion analyses with a finite element analysis software have been performed and results derived from different aging conditions (1 to 60 days of aging at 100 °C) at different electromigration temperatures have revealed that mass diffusion due to electromigration and associated stress migration actually reduces with the increment of aging time and thus increases time to failure in case of a flip chip solder joint. Simulation results have been found to be in good agreement with the experimental results available in literatures. These results can pave way to further detailed experimental investigation on effect of thermal aging on electromigration.

scholarly journals Random Voids Generation and Effect of Thermal Shock Load on Mechanical Reliability of Light-Emitting Diode Flip Chip Solder Joints

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 94 ◽  
Author(s):  
Jiajie Fan ◽  
Jie Wu ◽  
Changzhen Jiang ◽  
Hao Zhang ◽  
Mesfin Ibrahim ◽  
...  
Keyword(s):  
Solder Joint ◽  
Thermal Shock ◽  
Flip Chip ◽  
Heat Dissipation ◽  
Solder Joints ◽  
Light Emitting Diode ◽  
Shock Load ◽  
Thermal Shock Test ◽  
Mechanical Reliability ◽  
Light Emitting

To make the light-emitting diode (LED) more compact and effective, the flip chip solder joint is recommended in LED chip-scale packaging (CSP) with critical functions in mechanical support, heat dissipation, and electrical conductivity. However, the generation of voids always challenges the mechanical strength, thermal stability, and reliability of solder joints. This paper models the 3D random voids generation in the LED flip chip Sn96.5–Ag3.0–Cu0.5 (SAC305) solder joint, and investigates the effect of thermal shock load on its mechanical reliability with both simulations and experiments referring to the JEDEC thermal shock test standard (JESD22-A106B). The results reveal the following: (1) the void rate of the solder joint increases after thermal shock ageing, and its shear strength exponentially degrades; (2) the first principal stress of the solder joint is not obviously increased, however, if the through-hole voids emerged in the corner of solder joints, it will dramatically increase; (3) modelling of the fatigue failure of solder joint with randomly distributed voids utilizes the approximate model to estimate the lifetime, and the experimental results confirm that the absolute prediction error can be controlled around 2.84%.

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