Material Characterization and Low Cycle Fatigue Model of Low Ag Content Lead-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.

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Low Cycle Fatigue Behavior and Surface Feature by Image Processing of Sn-0.7Cu Lead-Free Solder

Fracture and Strength of Solids VI - Key Engineering Materials ◽

10.4028/0-87849-989-x.115 ◽

2006 ◽

pp. 115-120

Author(s):

Takehiko Takahashi ◽

Susumu Hioki ◽

Ikuo Shohji ◽

Osamu Kamiya

Keyword(s):

Image Processing ◽

Low Cycle Fatigue ◽

Fatigue Behavior ◽

Surface Feature ◽

Lead Free ◽

Lead Free Solder ◽

Cycle Fatigue ◽

Free Solder

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S031021 A Study on Low Cycle Fatigue Strength Properties of Lead Free Solder Materials

The Proceedings of Mechanical Engineering Congress Japan ◽

10.1299/jsmemecj.2011._s031021-1 ◽

2011 ◽

Vol 2011 (0) ◽

pp. _S031021-1-_S031021-3

Author(s):

Syungo SATAKE ◽

Takashi KAWAKAMI ◽

Takahiro KINOSHITA ◽

Hiroyuki KOBAYASHI ◽

Tetsuya KUGIMIYA ◽

...

Keyword(s):

Fatigue Strength ◽

Low Cycle Fatigue ◽

Strength Properties ◽

Lead Free ◽

Lead Free Solder ◽

Cycle Fatigue ◽

Free Solder

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Low-Cycle Fatigue Reliability Evaluation for Lead-Free Solders in Vehicle Electronics Devices

ASME 2007 InterPACK Conference, Volume 1 ◽

10.1115/ipack2007-33250 ◽

2007 ◽

Cited By ~ 11

Author(s):

Qiang Yu ◽

Tadahiro Shibutani ◽

Akifumi Tanaka ◽

Takahiro Koyama ◽

Masaki Shiratori

Keyword(s):

Fatigue Life ◽

Crack Propagation ◽

Low Cycle Fatigue ◽

Strain Range ◽

Reliability Evaluation ◽

Lead Free ◽

Generation Process ◽

Lead Free Solder ◽

Cycle Fatigue ◽

Free Solder

The changeover from eutectic Sn-Pb solder to lead-free solder (Sn-Ag-Cu) has been driven by environmental concerns in the last few years. In this study, in order to obtain the low-cycle fatigue characteristic of Sn-Ag-Cu lead-free solder joints, an isothermal mechanical fatigue test with a large strain range, which can clarify the crack generation process and shorten the examination time, was carried out. FEM analysis was also performed in order to evaluate the relationship between the inelastic strain range and the low-cycle fatigue life. As a result, compared with fatigue life longer than 1000 cycles, the scatter of the fatigue cycles from 100 to several hundred cycles becomes larger. So, it seems that it is necessary to carefully evaluate the low-cycle fatigue life in the reliability evaluation. Moreover, in large chip components, not only crack initiation, but also crack propagation, affects the failure life. Thus, the crack path was simulated and the failure cycle of the large chip was evaluated based on Miner’s rule, and reliability of including the fatigue crack propagation can be evaluated by the analytical approach.

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Tensile and Fatigue Properties of Miniature Size Specimen of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge Lead-Free Solder

Materials Science Forum ◽

10.4028/www.scientific.net/msf.941.2081 ◽

2018 ◽

Vol 941 ◽

pp. 2081-2086

Author(s):

Masaki Yokoi ◽

Tatsuya Kobayashi ◽

Ikuo Shohji

Keyword(s):

Tensile Strength ◽

Fatigue Life ◽

Low Cycle Fatigue ◽

Ternary Eutectic ◽

Lead Free ◽

Fatigue Properties ◽

Lead Free Solder ◽

Cycle Fatigue ◽

Proof Stress ◽

Free Solder

Tensile and low cycle fatigue properties of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge (mass%) lead-free solder were investigated using miniature size specimens and obtained data were compared to those of Sn-3.0Ag-0.5Cu (mass%). The microstructure of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge consists of dendritic β-Sn phases and ternary eutectic phases surrounding them which are composed of β-Sn, (Cu,Ni)6Sn5 and Ag3Sn. Tensile strength and 0.1% proof stress of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge are superior to those of Sn-3.0Ag-0.5Cu at 25°C and 150°C. However, elongation of it is inferior to that of Sn-3.0Ag-0.5Cu at both temperatures. Fatigue lives of both alloys obey the Manson-Coffin equation and are analogous at 25°C. Although fatigue lives of both alloys decrease at 150°C, the fatigue life of Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge is inferior to that of Sn-3.0Ag-0.5Cu. At 150°C, the crack mainly progresses at grain boundaries of recrystallized grains. Sn-3.5Ag-0.5Cu-0.07Ni-0.01Ge has several grain boundaies which can be the origin of the crack so that fatigue lives degrade at 150°C.

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