Modeling and experimentation of creep-fatigue and failure of low-profile quad flat package under thermal cycle

Author(s):  
Ayda Halouani ◽  
Abel Cherouat ◽  
Mariem Miladi Chaabane ◽  
Mohamed Haddar

An experimental investigation and numerical modeling using multiphysics finite element method were performed to study the thermal failure mechanism of low-profile quad flat package solder joints of memory module due to low-cycle fatigue. The strain, stress, and number of cycles to failure have been calculated according to a strain life Coffin–Manson and energy-based Morrow fatigue models. Scanning electron microscopy imaging at the end of thermal cycle was used to evaluate the damage initiation and propagation. The effect of the solder volume on fatigue life of solder joints was discussed. Through analyses of theoretical results and experimental data on fatigue life, cracks initiation and propagation have been highlighted and their possible causes have been discussed.

1990 ◽  
Vol 112 (2) ◽  
pp. 100-103 ◽  
Author(s):  
D. S. Stone

Two models are proposed for relating the metallurgy of the solder to the growth of fatigue cracks through solder joints. These models illustrate how different aspects of the creep behavior can contribute to the so-called “creep-fatigue interaction”. The first model treats fatigue crack growth through the solder, far from the interface between solder and substrate. Either an intragranular or intergranular path may be taken depending upon conditions of loading. Intragranular fatigue dominates when the cycle frequency is high, in which case failure life is governed by the Coffin-Manson law. Intergranular failure occurs at low frequencies because grain boundary sliding at low frequencies allows the grain boundaries to become exposed to the atmosphere, which in turn causes oxidation. This model predicts the effects of frequency, strain amplitude, and grain size on fatigue life. In the second model, the fatigue crack travels within the interface region between solder and substrate. Here, the strain introduced in the solder joint during fatigue is not relevant; instead, the stress transferred to the interface is more important. The second model considers the effect of solid solution concentration on fatigue life. The predictions of both models agree reasonably well with published fatigue data from solders and solder joints.


Author(s):  
Masanori Ando ◽  
Yuichi Hirose ◽  
Shingo Date ◽  
Sota Watanabe ◽  
Yasuhiro Enuma ◽  
...  

Several innovative prediction methods of strain range have been developed in order to apply to the Generation IV plants. In a component design at elevated temperature, ‘strain range’ is used to calculate the fatigue and creep-fatigue damage. Therefore, prediction of ‘strain range’ is one of the most important issues to evaluate the components’ integrity during these lifetimes. To verify the strain prediction method of discontinues structures at evaluated temperature, low cycle fatigue tests were carried out with notched specimens. All the specimens were made of Mod.9Cr-1Mo, because it is a candidate material for a primary and secondary heat transports system components of JSFR (Japanese Sodium Fast Reactor). Deformation control fatigue tests and thermal fatigue tests were performed by ordinary uni-axial push-pull test machine and equipment generating the thermal gradient in the notched plate by induction heating. Stress concentration level was changed by varying the notch radius in the both kind of tests. Crack initiation and propagation process during the fatigue test were observed by the digital micro-scope and replica method. Elastic and inelastic FEAs were also carried out to estimate the ‘strain range’ for the prediction of fatigue life. Then the ranges of several strain predictions and estimations were compared with the test results. These predictions were based on the sophisticated technique to estimate the ‘strain range’ from elastic FEA. Stress reduction locus (SRL) method, simple elastic follow-up method, Neuber’s rule method and the methods supplied by elevated temperature design standards were applied. Through these results, the applicability and conservativeness of these strain prediction and estimation methods, which is the basis of the creep-fatigue life prediction, is discussed.


Author(s):  
Hirokazu Oriyama ◽  
Takashi Kawakami ◽  
Takahiro Kinoshita

Sn-Ag-Cu solder materials have been widely used for the mount process of electronics devices or semiconductor packages on print circuit board (PCB). The solder joints are sometimes opened under thermal cyclic loads as low cycle fatigue phenomenon. The fatigue life of solder joint has been investigated by many researchers with experimental and numerical methods. Generally, the induced thermal stress in solder joints should be relaxed as soon and creep damage is considered to be ignored in order to estimate lives of joints. However, it is probable that long term stress is applied to solder joints by the elastic follow-up phenomenon which are depending on the stiffness ratio between solder joints and the electronics device, because the elastic strain in PCB or the electronics device shifts to creep strain in solder joints gradually during a long time. Then the creep damage of solder joint should be counted for the mechanical design of mounted PCBs. And it is known that the interaction between creep damage and fatigue damage significantly shorten the life. In this study, it was discussed whether the interaction between fatigue damage and creep damage has to be considered or not for the mechanical design of the lead free solder joint with basic creep-fatigue tests at an elevated temperature.


Author(s):  
Takashi Kawakami ◽  
Takahiro Kinoshita ◽  
Hirokazu Oriyama

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.


2020 ◽  
Vol 26 (9) ◽  
pp. 3011-3021
Author(s):  
Ayda Halouani ◽  
Abel Cherouat ◽  
Mariem Miladi Chaabane ◽  
Mohamed Haddar

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