2004 Fiscal Year Final Research Report Summary
Novel Bonding Processes in Electronics Assembly for High-temperature Use by In-situ Control of Reaction
| Project/Area Number |
15560626
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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 |
HIROSE Akio Osaka University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (70144433)
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| Co-Investigator(Kenkyū-buntansha) |
KOBAYASHI F.kojiro Osaka University, Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (70026277)
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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| Project Period (FY) |
2003 – 2004
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| Keywords | High melting point micro joining / Electronics assembly / metallo-organic Ag nanoparticle / Low temperature sintering / Interfacial reaction / Intermetallic compound |
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| Research Abstract |
The following novel joining processes in electronics assembly for high-temperature use that had a bonding temperature below 300℃ and a heat resistance higher than 260℃ were proposed in the present research.
1.Raising melting temperature by the reaction between solder and plating
The melting temperature of the solder layer was raised by the formation of an intermetallic compound through the reaction between a Sn-Ag solder and Ni-Co/Au plating during the reflow process at 240℃. The rapid diffusion of Ni and Co through a (Ni, Co)Sn_2 reaction layer could promote formation of the intermetallic compound. As a result the bonding layer having a melting temperature higher than 260℃ could be obtained after the reflow soldering.
2.Bonding process using metallo-organic Ag nanoparticles
A novel bonding process using Ag metallo-organic nanoparticles as a new application of nanotechnologies was proposed. The average size of the Ag nanoparticle is approximately 11 nm, and each nanoparticle is covered with an organic shell. Usually, the agglomeration of metallic nanoparticles is unavoidable due to its large surface energy. However, on the account of the organic shell, these Ag nanoparticles exist individually, and once the organic shell has been removed, these Ag nanoparticles turn activated and abruptly agglomerate. We analyzed its thermal characteristics, applied the agglomerating of the nanoparticles to Cu-to-Cu joining, and researched the influence of the bonding condition, such as bonding pressure, temperature or holding time, upon the joint strengths. The metallurgical bonding between Ag and Cu was achieved and a dense bonding layer of sintered Ag was realized. The joint using the nanoparticles had a melting point equivalent to that of Ag and a joint strength of 30-40 MPa, which is strong enough to be applied as an electronics assembly for high-temperature use. In addition, it came to the conclusion that the strengths increased in accord with the aforesaid three parameters.
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