• Journal of the Microelectronics and Packaging Society
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• v.15 no.4
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• pp.31-39
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• 2008

To develop the MEMS cap bonding process without cavity formation, we electroplated Cu/Sn rim structures and measured the bonding characteristics for the Cu/Sn rims of $25{\sim}400{\mu}m$ width. As the effective device-mounting area ratio decreased and the failure strength ratio increased for wider Cu/Sn rim, these two properties were estimated to be optimized for the Cu/Sn rim with 150 ${\mu}m$ width. Complete bonding was accomplished at the whole interfaces of the Cu/Sn packages with the rim widths of 25 ${\mu}m$ and 50 ${\mu}m$. However, voids were observed locally at the interfaces with the rim widths larger than 100 ${\mu}m$. Such voids were formed by local non-contact between the upper and lower rims due to the surface roughness of the electroplated Sn.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.4
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• pp.23-28
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• 2009

We investigated the wafer-level MEMS capping process for which cavity formation in Si wafer was not required. Ni caps were formed by electrodeposition on 4" Si wafer and Ni rims of the Ni caps were bonded to the Cu rims of bottom Si wafer by using epoxy. Then, top Si wafer was debonded from the Ni cap structures by using SnBi layer of low melting temperature. As-evaporated SnBi layer was composed of double layers of Bi and Sn due to the large difference in vapor pressures of Bi and Sn. With keeping the as-evaporated SnBi layer at $150^{\circ}C$ for more than 15 sec, SnBi alloy composed of eutectic phase and Bi-rich $\beta$ phase was formed by interdiffusion of Sn and Bi. Debonding between top Si wafer and Ni cap structures was accomplished by melting of the SnBi layer at $150^{\circ}C$.

• Korean Journal of Heritage: History & Science
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• v.48 no.2
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• pp.110-119
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• 2015

Bronzes, Earthenwares and various artifacts were excavated from Pungnap earthen fortress in the early Baekje age in Korea. This study was performed in order to identify the manufacture technology of bronze artefacts and provenance of lead in bronzes. Microstructure and chemical composition results show that 3 of them are Cu-Sn-Pb alloys in which an intentional lead addition was carried out and one is tin bronze showing straight twin structure within crystal grains. Also $CuFeS_2$ or $Cu_5FeS_4$ was used as raw materials through the detection of S and Fe as trace elements. The lead isotope results could be matched with one of the zones of southern Korea and China on the East Asian map. This results shows that data were plotted either in zone 2 or zone 3 of the South Korean galena map. However, one of bronze artifacts was matched with the zone of Northern China.

• Korean Journal of Heritage: History & Science
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• v.49 no.3
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• pp.4-11
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• 2016

This study compares eight bronze spoons in the Goryeo Dynasty and analyzes their components and lead isotopes in order to confirm the relationship between their production sites and excavation sites. Most of the excavated spoons have elliptical heads, and their handles are categorized into two types. Bronze spoons are made of binary Cu-Sn alloys, but Pb is not added. The same artifacts can have different trace elements depending on location, and the spoons had high Ag content. According to an analysis of their lead isotopic ratio, they were made with raw materials produced in Zone 3 of the South Korean galena map. If the data of the trace elements in the raw ores of the bronze is accumulated, it can be used to indicate the provenance of the artifacts.