A model for low-cycle fatigue of surface mount solder joints

2002 ◽  
Author(s):  
C.G. Schmidt
Keyword(s):  
Solder Joints ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Surface Mount

A Study on Strain Concentration Around V Notch in Lead Free Solder Material and the Low Cycle Fatigue Life

2015 ◽  
Author(s):  
Takashi Kawakami ◽  
Takahiro Kinoshita ◽  
Hirokazu Oriyama
Keyword(s):  
Fatigue Life ◽  
Solder Joints ◽  
Low Cycle Fatigue ◽  
Lead Free ◽  
Design Rule ◽  
Lead Free Solder ◽  
Cycle Fatigue ◽  
Stress Strain ◽  
Test Pieces ◽  
Free Solder

Solder joints are sometimes opened under thermal cyclic loads as low cycle fatigue phenomena. The fatigue crack is usually initiated around the edge of the interface where stress and strain very severely concentrate, having stress strain singularity. In this study, Sn-3.0Ag-0.5Cu test pieces with V shape notch were supplied to low cycle fatigue tests at 100°C. And inelastic stress strain simulations, which were based on time-dependent non-unified material model, were carried out under several cyclic load levels to obtain strain distributions around the bottom of the V notch. By results of fatigue test and inelastic simulation, the depth from the bottom of the V notch, where the strain range agrees with the prediction of the fatigue life based on smooth test pieces on Coffin-Manson rule, was investigated as the mechanical design rule for lead free solder joints.

Thermal Strain Measurements of Solder Joints in Second Level Interconnections Using Moire Interferometry

1992 ◽  
Vol 114 (1) ◽  
pp. 88-92 ◽  
Author(s):  
Yifan Guo ◽  
Charles G. Woychik
Keyword(s):  
Thermal Expansion ◽  
Solder Joints ◽  
Coefficient Of Thermal Expansion ◽  
Low Cycle Fatigue ◽  
Thermal Strain ◽  
Moiré Interferometry ◽  
Moire Interferometry ◽  
Mechanical Reliability ◽  
Surface Mount ◽  
Inherent Strength

Low cycle fatigue of solder joints is one of the major kinds of failures in second level interconnections of an electronic package. The fatigue failure is caused by thermal strains which are created from a mismatch of coefficients of thermal expansion (CTE) that occurs between two levels of packaging. As the package approaches smaller dimensions, measurements of thermal strains in the solder interconnections become very difficult. In this paper, moire interferometry technique was applied to evaluate the thermal strains in the second level interconnections for both conventional pin-in-hole (PIH) packages and surface mount components. The coefficient of thermal expansion of each component was measured. Thermal strain distributions in the solder interconnections were determined, and reliability issues were discussed. The strains in solder joints of the PIH components were much higher than those of the stacked surface mount components. Even though the surface mount components had a lower inherent strength, their overall mechanical reliability was much higher since they had practically no localized strain concentrations.

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