Fatigue of Solder Joints in Surface Mount Devices

Ball shear testing is typically conducted in Wafer level chip scale package (WLCSP) fabrication to estimate the strength of the solder ball attachment. Generally, the solder ball shear strength is dependent on the solder ball size, pad size, solder/pad interface treatment, reflow temperature and time. Solder ball strength is also a function of ram speed and height at which the ball is sheared with respect to the wafer. Recent investigations suggest that ball shear test is being used as an indicator for board level reliability of assemblies. In current market lead time for launching a new product is very short. Unfortunately, it takes several weeks to qualify a new product by board level qualification process. If there is a methodology through which one can predict the board level performance by extrapolating the wafer level test, it will save great amount of resources in testing and millions of dollars worth of testing time. In the first part of this study, we conducted a wafer level ball shear test. A DOE was created for varying wafer level structural parameters like solder ball size and type. Ball shear tests and Accelerated thermal cycling have similar failure signatures of compression on inner side and tension on outer side. Thus, for specific cases there is a possibility of correlating the two failure methodologies based on their failure signatures. Strain rate for ball shear test was determined based on shear speed and solder pad diameter. Strain rate for accelerated thermal cycling was determined based on difference in CTE between board and package. In this paper, results from ball shear test and accelerated thermal cycling are compared to find correlations for specific cases. The correlations derived from this study are statistical and empirical.

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“…The median cyclic fatigue life can be calculated by linear damage accumulation as expressed in the equation [46][47].…”

Section: Strain Rate Partitioning Modelmentioning

confidence: 99%

Effect of Structural Design Parameters on Wafer Level CSP Ball Shear Strength and Their Influence on Accelerated Thermal Cycling Reliability

Lakhkar

Viswanadham

Agonafer

2009

Volume 5: Electronics and Photonics

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“…C is dependent on failure criteria and the solder microstructure, which is 890%. Shine and Fox [17] reported that fatigue life due to creep strains shows much correlation to matrix creep but relatively little correlation to grain boundary creep. Thus, the effect on the creep strains due to the grain boundary sliding of the solder bumps is neglected in this paper.…”

Section: Solder Fatigue Prediction Modelsmentioning

confidence: 99%

Investigation on flip chip solder joint fatigue with cure-dependent underfill properties

Yang

Zhang

Ernst

et al. 2003

IEEE Trans. Comp. Packag. Technol.

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“…The values of the stress exponents reported for solder joints range from -2-6 (Solomon, 1986;Hall, 1987;Enke and Sandor, 1988;Shine and Fox, 1988). The different joint geometries and joint processing techniques used in each of these experiments may account for the scatter in the reported n values.…”

Section: Creep Datamentioning

confidence: 99%

Creep in Shear of Experimental Solder Joints

Tribula

Morris

1990

Journal of Electronic Packaging

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Thermal fatigue failures of solder joints in electronic devices are a great concern in the electronics industry. Since the fatigue load is often in shear the details of thermal fatigue failure in shear are of particular interest. Recent work indicates that similar failure mechanisms operate in both thermal fatigue in shear and unidirectional creep in shear. Additionally, since the operative temperatures during thermal fatigue represent high solder homologous temperatures, creep deformation is certainly involved. These factors and the relative case of conducting creep experiments encourage the study of solder joints under shear creep conditions. This work presents steady state shear creep rate vs. shear stress data for several solder compositions, including the binary eutectic alloy and Pb-Sn alloyed with small amounts of Bi, Cd, In, and Sb, in a joint configuration. These data indicate that conventional creep mechanisms operate in the temperature and shear strain rate ranges studies. Extensive microstructural information is also reported. The microstructural evolution under creep conditions indicates that the instability of the as-cast binary Pb-Sn eutectic microstructure initiates creep failure. Changes of the as-solidified microstructure with the third element addition are reported as are the microstructural responses of each of these alloys to creep deformation. The efficacy of postponing the microstructural instability with the addition of small amounts of ternary elements is discussed.

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Fatigue of Solder Joints in Surface Mount Devices

Cited by 69 publications

References 20 publications

Effect of Structural Design Parameters on Wafer Level CSP Ball Shear Strength and Their Influence on Accelerated Thermal Cycling Reliability

Effect of Structural Design Parameters on Wafer Level CSP Ball Shear Strength and Their Influence on Accelerated Thermal Cycling Reliability

Investigation on flip chip solder joint fatigue with cure-dependent underfill properties

Creep in Shear of Experimental Solder Joints

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