2006 Fiscal Year Final Research Report Summary
Dvelopment of Sn-Bi Based Low Temperature Solders which Enables Step Soldering
| Project/Area Number |
17560633
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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 |
Material processing/treatments
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| Research Institution | Osaka University |
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Principal Investigator |
UENISHI Keisuke Osaka University, Graduate school of Engineering, Associate Professor, 大学院工学研究科, 助教授 (80223478)
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| Co-Investigator(Kenkyū-buntansha) |
SATO Takehiko Osaka University, Graduate school of Engineering, Professor, 大学院工学研究科, 教授 (60379112)
SHOUJI Ikuo Gunma University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (00323329)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Micro Joining / Low Temperature Packaging / Lead Free Solder / Interfacial Reaction / Electronics Packaging / Evaluation of Reliabilty / Microstructure / Tin Bismuth Alloy |
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| Research Abstract |
Effect of Ag Addition to Sn-Bi Eutectic Solders on the Microstructure and Properties of Joints with Cu. About 0.5mass% of Ag addition to the Sn-Bi changes the eutectic microstructure fine through Sn-Bi-Ag3Sn ternary eutectic solidification. With decreasing the eutectic microstructure, the ductility increased more than that of Sn-Pb solders especially at the rapid stress speed. Addition of Ag more than 1 mass%, however, formed coarse and uniaxial Ag3Sn which decreased the ductility of solders. rand improved its ductility.
By using Sn-Ag-Bi solders with low melting temperature about 410K, low temperature reflow soldering with Cu pad can be achieved at 433K. Microjoint with Cu using Sn-Bi-Ag solder exhibited the comparable tensile strength and thermal cycle fatigue property with that of Sn-Ag-Cu solders. Be the advantages of the low temperature soldering at 433K, residual stress caused by reflow soldering became smaller and fracture between Cu pad and substrate was drastically supressed. For the joints using Sn-Bi-Ag, fracture by tensile test occurs at the interface between Cu6Sn5 reaction layer and solder. The degradation of joint strength during the aging was caused by the growth of reaction layer. The growth behavior of reaction layer, however, was eastimated to be almost same as that for the joints using Sn-Ag-Cu solders by the kinetic analysis.
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Research Products
(12 results)
