| Project/Area Number |
17560075
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | Toyama Prefectural University |
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Principal Investigator |
MORI Takao Toyama Prefectural University, Engineering Faculty, Professor (30275078)
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| Co-Investigator(Kenkyū-buntansha) |
YU Qiang Yokohama National University, Graduate School of Engineering, Associate Professor (80242379)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥2,450,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥150,000)
Fiscal Year 2007: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2006: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2005: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | Lead free solder / Phase growth / Thermal fatigue lifetime / Eletric substrate / Reliability |
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| Research Abstract |
This research was performed in order to apply the estimation method of the thermal fatigue crack initiation lifetime by using the phase growth parameter to the improvement of the reliability and the reduction of the environmental affection for electric substrates. The fatigue tests of Sn-3.0Ag-0.5Cu solder joints were performed to improve the accuracy of the estimation method at the temperature of 125℃, and the phase size and the crack initiation were observed. Moreover, the finite element analyses of the solder joints were performed to compare the strain with the phase growth parameter and the thermal cycle tests of the solder joints were performed to examine the accuracy to predict the thermal fatigue crack initiation lifetime. Consequently, the results were obtained as follows. The phase size of β-Sn increases until some period but becomes constant after the period. The total phase size within the influence of both temperature and strain increase as number of loading cycles increasing. It is difficult to separate the phase size caused by strain from the total phase size, but it is found that the increment of the total phase size in solder joints is useful parameter to consider the phase growth process. Comparing the test results and the analysis results, the phase growth parameter of Sn-3.0Ag-0.5Cu solder joints is good agreement with the creep strain. Moreover, it is clarified that the accuracy to predict the thermal fatigue crack initiation lifetime is within ± 10% of the master curve which was gotten by the former investigation. Therefore, the base of the estimation method the strain history and the thermal fatigue lifetime was constructed. And it is confirmed that the base contributes the improvement of the reliability and reuse of the solder joints in the electric substrates.
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