• 한국분말재료학회지
• /
• 제17권6호
• /
• pp.470-476
• /
• 2010

In this study, Cu-10Sn and Cu-10Sn-2Ni-0.2Si alloys have been manufactured by spray casting in order to achieve a fine scale microstructure and high tensile strength, and investigated in terms of microstructural evolution, aging characteristics and tensile properties. Spray cast alloys had a much lower microhardness than continuous cast billet because of an improved homogenization and an extended Sn solid solubility. Spray cast Cu-Sn-Ni-Si alloy was characterized by an equiaxed grain microstructure with a small-sized (Ni, Si)-rich precipitates. Cold rolling of Cu-Sn-Ni-Si alloy increased a tensile strength to 1220 MPa, but subsequent ageing treatment reduced a ultimate tensile strength to 780 MPa with an elongation of 18%.

• 한국분말재료학회지
• /
• 제17권6호
• /
• pp.477-481
• /
• 2010

Cu-Sn based alloys were manufactured by gas atomization spray casting route in order to achieve a fine scale microstructure and a high tensile strength. The spray cast Cu-10Sn-2Ni-0.2Si alloy had an equiaxed grain microstructure, with no formation of brittle ${\delta}-Cu_{41}Sn_{11}$ phase. Aging treatment promoted the precipitation of finely distributed particles corresponding to ${\delta}-Ni_2Si$ intermetallic phase throughout the $\alpha$-(CuSn) matrix. The cold-rolled Cu-Sn-Ni-Si alloy had a very high tensile strength of 1200 MPa and an elongation of 5%. Subsequent aging treatment at $450^{\circ}C$ for 1h slightly reduced the tensile strength to 700 MPa and remarkably increased the elongation up to 30%. This result has been explained by coarsening the precipitates due to over aging and reducing the dislocation density due to annealing effects.

• 열처리공학회지
• /
• 제26권5호
• /
• pp.225-232
• /
• 2013

The influence of aging treatment, addition elements and rolling reduction ratio on the microstructure, mechanical, electrical and bendability properties of Cu-Ni-Si-P-x (x = Fe, Sn, Zn) alloys for connector material application was investigated. SEM/EDS analysis exhibited that Ni2-Si precipitates with a size of 20~100 nm were distributed in grains. Fe, Sn, Zn elemnets in Cu-Ni-Si-P alloy imporved the mechanical strength but it was not favor in increasing of electrical conductivity. As higher final rolling reduction ratio, the strength and electrical conductivity is increased after aging treatment, but it indicated excellent bendability. Especially, Cu-2Ni-0.4Si-0.5Sn-0.1Fe-0.03P alloy show the tensile strength value of 700MPa and the electrical conductivity was observed to reach a maximum of 40%IACS. It is optimal for lead frame and connector.

• 마이크로전자및패키징학회지
• /
• 제16권4호
• /
• pp.23-28
• /
• 2009

Si 기판의 캐비티 형성이 불필요한 웨이퍼-레벨 MEMS capping 공정을 연구하였다. 4인치 Si 웨이퍼에 Ni 캡을 전기도금으로 형성하고 Ni 캡 rim을 Si 하부기판의 Cu rim에 에폭시 본딩한 후, SnBi debonding 층을 이용하여 상부기판을 Ni 캡 구조물로부터 debonding 하였다. 진공증착법으로 형성한 SnBi debonding 층은 Bi와 Sn 사이의 심한 증기압 차이에 의해 Bi/Sn의 2층 구조로 이루어져 있었다. SnBi 증착 층을 $150^{\circ}C$에서 15초 이상 유지시에는 Sn과 Bi 사이의 상호 확산에 의해 eutectic 상과 Bi-rich $\beta$상으로 이루어진 SnBi 합금이 형성되었다. $150^{\circ}C$에서 유지시 SnBi의 용융에 의해 Si 기판과 Ni 캡 구조물 사이의 debonding이 가능하였다.

• 대한금속재료학회지
• /
• 제48권8호
• /
• pp.749-756
• /
• 2010

Low carbon steels were oxidized isothermally at 1050 and $1180^{\circ}C$ for 4 hr in air in order to determine the effect of alloying elements Si, S, Cu, Sn, and Ni on oxidation. For oxidation resistance of low carbon steels, the beneficial elements were Si, Cu, and Ni, whereas the harmful elements were S and Sn. The most active alloying element, Si, was scattered inside the oxide scale, at the scale-alloy interface, and as an internal oxide precipitate. The relatively noble elements such as Cu and Ni tended to weakly segregate at the scale-alloy interface. Sulfur and Sn were weakly, uniformly distributed inside the oxide scale. Excessively thick, non-adherent scales containing interconnected pores formed at $1180^{\circ}C$.

• 마이크로전자및패키징학회지
• /
• 제13권1호통권38호
• /
• pp.23-29
• /
• 2006

Si-웨이퍼와 FR-4 기판을 상온에서 초음파 접합한 후, 접합부의 신뢰성을 평가하였다. Si-웨이퍼 상의 UBM(Under Bump Metallization)은 위에서부터 Cu/ Ni/ Al을 각각 $0.4{\mu}m,\;0.4{\mu}m,\;0.3{\mu}m$의 두께로 전자빔으로 증착하였다. FR-4 기판위의 패드는 위에서부터 Au/ Ni/ Cu를 각각 $0.05{\mu}m,\;5{\mu}m,\;18{\mu}m$의 두께로 전해 도금하여 형성하였다. 접합용 솔도로는 Sn-3.5wt%Ag을 두께 $100{\mu}m$으로 압연하여 사용하였다. 시편의 초음파 접합을 위하여 초음파 접합 시간을 0.5초에서 3.0초까지 0.5초 단위로 증가시키면서 상온에서 접합하였으며, 이 때 출력은 1,400W로 하였다. 실험 결과, 상온 초음파 접합법에 의해 신뢰성 있는 'Si-웨이퍼/솔더/FR-4기판' 접합부를 얻을 수 있었다. 접합부의 전단 강도는 접합 시간에 따라 증가하여 접합 시간 2.5초에서 65N으로 가장 높게 측정되었다. 이 후 접합 시간 3.0초에서는 전단 강도가 34N으로 감소하였는데, 이는 초음파 접합시간이 과도해지면서 Si-웨이퍼와 솔더 사이의 계면을 따라 균열이 발생되었기 때문으로 판단된다. 초음파 접합에 의해 Si-웨이퍼와 솔더 사이에서 생성된 금속간 화합물은 ($(Cu,Ni)_{6}Sn_{5}$)으로 확인되었다.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2005년도 춘계학술발표대회 개요집
• /
• pp.54-56
• /
• 2005

Ultrasonic soldering using of Si-wafer to FR-4 PCB atroom temperature was investigated. Sn3.5Ag foil rolled $100{\mu}m$ was used for solder. The UBM of Si-die was Cu/ Ni/ Al from top to bottom and its thickness was $0.4{\mu}m$, $0.4{\mu}m$, $0.3{\mu}m$ respectively. Pad on FR-4 PCB comprised of Au/ Ni/ Cu from top to bottom and its thickness was $0.05{\mu}m$, $5{\mu}m$, $18{\mu}m$ respectively. The ultrasonic soldering time was changed from 0.5sec to 3.0sec and its power 1400W. As experimental result, reliable bond joint by ultrasonic at room temperature was obtained. The shear strength increased with soldering time up to 2.5 sec. That means at 2.5sec, the shear strength showed maximum rate of 65.23N. The strength decreased to 33.90N at 3.0 sec because the cracks generated along the intermetallic compound between Si-wafer and Sn-3.5mass%Ag solder. intermetallic compound produced by ultrasonic between the solder and the Si-die was $(Cu, Ni)_{6}Sn_{5}$ and the intermetallic compound between solder and pad on FR-4 was $(Ni, Cu)_{3}Sn_{4}$.

• 한국표면공학회지
• /
• 제35권1호
• /
• pp.11-16
• /
• 2002

As environmental concerns increasing, the electronics industry is focusing more attention on lead free solder alternatives. In this research, we have researched wettability of intermediate solder of Sn3Ag9Bi5In, which include In and Bi and has similar melting temperature to Sn37Pb eutectic solder. We investigated the wetting property of Sn3Ag9Bi5In. To estimate wettability of Sn3Ag9Bi5In solder on various substrates, the wettability of Sn3Ag9Bi5In solder on high-pure Cu-coupon was measured. Cu-coupon that plated Sn, Ni and Au/Ni and Si-wafer adsorbed Ni/Cu under bump metallurgy on one side. As a result, the wetting property of Sn3Ag9Bi5In solder is a little better than that of Sn37Pb and Sn3.5Ag.

• 한국마이크로전자및패키징학회:학술대회논문집
• /
• 한국마이크로전자및패키징학회 2003년도 기술심포지움 논문집
• /
• pp.84-87
• /
• 2003

Since Pb-free solder alloys have been used extensively in microelectronic packaging industry, the interaction between UBM (Under Bump Metallurgy) and solder is a critical issue because IMC (Intermetallic Compound) at the interface is critical for the adhesion of mechanical and the electrical contact for flip chip bonding. IMC growth must be fast during the reflow process to form stable IMC. Too fast IMC growth, however, is undesirable because it causes the dewetting of UBM and the unstable mechanical stability of thick IMC. UP to now. Ni and Cu are the most popular UBMs because electroplating is lower cost process than thin film deposition in vacuum for Al/Ni(V)/Cu or phased Cr-Cu. The consumption rate and the growth rate of IMC on Ni are lower than those of Cu. In contrast, the wetting of solder bumps on Cu is better than Ni. In addition, the residual stress of Cu is lower than that of Ni. Therefore, the alloy of Cu and Ni could be used as optimum UBM with both advantages of Ni and Cu. In this paper, the interfacial reactions of Sn-3.5Ag-0.7Cu solder on Ni-xCu alloy UBMs were investigated. The UBMs of Ni-Cu alloy were made on Si wafer. Thin Cr film and Cu film were used as adhesion layer and electroplating seed layer, respectively. And then, the solderable layer, Ni-Cu alloy, was deposited on the seed layer by electroplating. The UBM consumption rate and intermetallic growth on Ni-Cu alloy were studied as a function of time and Cu contents. And the IMCs between solder and UBM were analyzed with SEM, EDS, and TEM.

• 한국마이크로전자및패키징학회:학술대회논문집
• /
• 한국마이크로전자및패키징학회 2002년도 추계기술심포지움논문집
• /
• pp.55-58
• /
• 2002

The possibility of SnCuX Solder as alternative for Pb-free Solder have been investigated in this study. SnCuX Solder balls(500${\mu}{\textrm}{m}$) were placed on Si-wafer which is Al/Ni/Cu(500nm/$4{\mu}{\textrm}{m}$/$4{\mu}{\textrm}{m}$)UBM layer. After reflow soldering at $250^{\circ}C$, shear strength and microstructure were analyzed. The results showed that the shear strength(500gf) of SnCuX was higher than that of SnCuX at $230^{\circ}C$ and $Cu_6Sn_5$ intermetallic compounds were formed between Cu and SnCuX Solder layers