2007 Fiscal Year Final Research Report Summary
Advanced Assessment Methodology of Lead-free Solder Joints under Multi-loads in Three-dimensional Electronic Packaging
| Project/Area Number |
18360056
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | Yokohama National University |
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Principal Investigator |
YU Qiang Yokohama National University, Division of System Research, Associate Professor (80242379)
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| Co-Investigator(Kenkyū-buntansha) |
SHIRATORI Masaki Yokohama Nationa University, Division of System Research, Professor (60017986)
SHIBUTANI Tadahiro Yokohama Nalional University, Division of System Research, Research Associate (10332644)
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| Project Period (FY) |
2006 – 2007
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| Keywords | 3D-Packaging Technology / Solder Joints / Multi-axial stresses / Low-cycle fatigue / Creep / Fatigue Life / Finite Element Method / Strain Measurement |
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| Research Abstract |
This paper reports a fundamental methodology of the assessment for thermal fatigue reliability of lead-free solder joints in three-dimensional electronic packaging. In particular, multi-loads condition provides complex failure mechanism to the assessment of reliability. Nanoindentation tests were carried out for lead or lead-free solder balls to evaluate mechanical properties under multi-axial stresses. Ratchet and transition of creep mechanism were found during the indentation creep. In the case of thin film such as plating finishes, mechanical properties may change due to multi-axial stresses. Based on measured properties, tin whisker initiation was examined. Transition from power-law creep to diffusion creep accelerates atoms migrating rate and then tin whiskers initiate due to the accumulation of atoms at the localized area. Another discussion is the reliability of connectors under multi loads. Three point bending tests were performed to evaluate the low-cycle fatigue under multi-loads. Inelastic strain range, which is the key to fatigue life of solder joints, increases with the multi loads. Finally, a methodology to assess the fatigue life of connectors under multi loads was developed.
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[Journal Article] Effective Acquisitions of Plastic, Creep, Viscoplastic Parameters of Solder Using the Stress Relaxation Method2006
Author(s)
Tanimura, T., Yu, Q., Shibutani, T., Jin, J.C., Shiratori, M
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Journal Title
Proceedings of EMAP 2006
Pages: 658-666
Description
「研究成果報告書概要(欧文)」より
