• Proceedings of the KWS Conference
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• 2002.10a
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• pp.481-486
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• 2002

We have investigated the effects of plating materials for Cu lead (Sn-lOPb, AwPdJNi, Sn-3.5Ag, Sn-3Bi and Sn-0.7Cu) on properties of QFP joints using a Sn-8Zn-3Bi solder. The results were compared with the joints using Sn-3. 5Ag-0. 7Cu and Sn-37Pb solders. As a result, the joints with the Sn-3.5Ag, Sn-3Bi and Sn-0.7Cu plated Cu lead had the reliability comparable to those of the Sn-3.5Ag-0.7Cu and Sn-37Pb soldered joints with respect to the joint strength after the high temperature holding tests at 348K to 423k. In particular, the joint with the Sn-3.5Ag plated Cu lead had the best reliability. This is caused by the low growth rate of a Cu-Sn interfacial reaction layer that degrades the joint strength of the soldered joints. Consequently, the Sn-3.5Ag plating was found to be most feasible plating for the Sn-8Zn-3Bi soldered joint.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.218-220
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• 2006

Sn-3.0Ag-0.5Cu solder is widely used as micro-joining materials of flip chip package(FCP) because of the fact that it causes less dissolution and has good thermal fatigue property. However, compared with ternary electroplating in the manufacturing process, binary electroplating is still used in industrial field because of easy to make plating solution and composition control. The objective of this research is to fabricate Sn-3.0Ag-0.5Cu solder bumping having accurate composition. The ternary Sn-3.0Ag-0.5Cu solder bumping could be made on a Cu pad by sequent binary electroplating of Sn-Cu and Sn-Ag. Composition of the solder was estimated by EDS and ICP-OES. The thickness of the bump was measured using SEM and the microstructure of intermetallic-compounds(IMCs) was observed by SEM and EDS. From the results, contents of Ag and CU found to be at $2.7{\pm}0.3wt%\;and\;0.4{\pm}0.1wt%$, respectively.

• Korean Journal of Materials Research
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• v.3 no.6
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• pp.668-677
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• 1993

The microstructural and shear tests of STS304/, STS430/ and low-C steel/Cu joints brazed using Cu-P, Cu-P-Sn(four type) and Cu-P-Sn-Ag(three type) filler metals at 1003 and 1033K for 1.2ks in Ar atomsphere were performed. Interfacial microstructures were divided into three type ; first, reaction layer contained cracks second, dispersed layer without cracks third, dispersed layer and reaction layer contained cracks. The joints composed only of dispersed layer without cracks have the high shear strength of above 40-60 MPa and result in failure in copper base metal. Low shear strength and joint failure result from the formation of reaction layer which induced cracks. The reaction layer is a Fe-P compound. This tendency of microstructure and shear strength depends on the existence and/or nonexistence of Sn in filler metals as well as Ni (and Cr) in base metals.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.184-186
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• 2006

Sn-3Ag-0.5Cu is one of candidate as an alternative approach to conventional lead-tin solder. In order to evaluate that creep characteristic of QFP, we used Sn-3Ag-0.5Cu where the operating temperature is $100^{\circ}C$. The specimens were loaded to failure at average pull strength in the range of 20% to 25%, X-ray machine is used to eliminate effect of void. In this paper, relation of time-displacement and steady state creep rate was studied, and used to analyze the experimental result.

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.36-38
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• 2006

We investigated that the metallurgical, mechanical and electrical properties of the Sn-3.SAg/Cu ball grid array (BGA) solder joints at a reflow temperature of $255^{\circ}C$ for different reflow times of 10, 60, 300 and 1800 s. Two different intermetallic compound (IMC) layers, consisting of scallop-shaped $Cu_6Sn_5$ and very thin $Cu_3Sn$, formed at the solder/substrate interface, and their thicknesses increased with increasing reflow time. The shear force peaked after reflow for 60 s, and then significantly decreased with increasing reflow time. The fracture occurred along the solder ball in the initial reflow, but the fraction of the brittle fracture increased with increasing reflow time. The IMC growth and the volume of Cu dissolved in the solder balls affected the electrical property.

• Korean Journal of Metals and Materials
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• v.48 no.12
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• pp.1056-1063
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• 2010

We present a new joining method for Pd-Cu membrane foils used as permeation tubes to collect $CO_2$. Since foils have poor mechanical strength, joining should be done at low temperatures to reduce residual stresses and without joining pressure. This contradicts the well known conditions for good contact between base materials that determines joint qualities. We selected Sn-Ag-Cu alloys that are highly reactive with Pd and Cu as a filler metal. As the filler melts at joining temperatures as low as $220{\sim}280^{\circ}C$, Pd and Cu are dissolved into the melt and react with the filler elements, which raises the melting temperature of the filler based on eutectic structures among the elements. Then, isothermal solidification progresses for the rest of the joining time. Intermetallic compounds (IMC) in the joints, one of the main factors for brittle joints, are inevitably formed. However, by optimizing both joining time and temperature, we balanced the wettability with IMC. Sealing test results confirmed that the joints are mechanically reliable during operation.

• Journal of the Microelectronics and Packaging Society
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• v.28 no.2
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• pp.95-103
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• 2021

Sn-58Bi-xRu composite solders were prepared by adding Ru nanoparticles to Sn-58Bi, a typical low-temperature solder, and the interfacial reaction and solder joint reliability were analyzed by reacting with Cu/OSP and ENIG surface treated PCB boards. The Cu₆Sn₅ IMC formed by the reaction with Cu/OSP had little change in thickness depending on the Ru content, and ductile fracture occurred inside the solder during the high-speed shear test without any significant change even after 100 hr aging. In reaction with ENIG, the Ni₃Sn₄ IMC thickness tended to decrease as the Ru content increased, and ENIG-specific brittle fracture was found in some specimens. Since Ru element is not found near the interface, it is judged not to be significantly involved in the interfacial reaction, and it is analyzed that it mainly exists together with the Bi phase.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.399.1-399.1
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• 2016

p-type 반도체 물질로 알려진 $Cu_2O$에 Li 이온을 doping하면 Cu 이온 자리에 Li이온이 치환되어 p-type의 특성이 더욱 강하게 나타내는 것으로 알려져 있다. 이에 본 연구에서는 RF magnetron sputtering방법으로 성막한 p-type형 $Li:Cu_2O$박막의 특성을 연구하고 이를 $Li:Cu_2O-ZnO$ pn 접합 유연 나노제너레이터에 적용하였다. $Li:Cu_2O$ 성막시 $O_2$ 분압을 변수로 100nm 두께의 $Li:Cu_2O$ 박막을 성막하여 전기적, 광학적, 구조적, 표면 특성을 분석하였다. Hall measurement 측정 결과 $Li:Cu_2O$ 박막은 정공을 Major Carrier로 갖는 p-type 반도체임을 확인하였고, $O_2$의 분압이 증가할수록 Mobility 및 Carrier Concentration이 증가함을 확인하였다. 최적조건에서 광학적 투과도는 약 45%를 보였으며, 투과도를 통해 계산한 band gap은 약 2.03eV로써 일반적인 산화물 반도체의 작은 밴드갭을 가지고 있음을 알 수 있었다. 또한 Ellipsometer분석을 통해 $Ar:O_2$ 비가 $Li:Cu_2O$ 굴절률 및 흡광도에 미치는 영향을 연구하였으며, FE-SEM(Field Emission Scanning Electron Microscope)을 통해 표면을 분석하였다. 또한 XRD(X-ray diffractometer), TEM(Transmission Electron Microscope) 분석을 통하여 상온에서 성막한 $Li:Cu_2O$ 박막의 미세구조를 연구하였다. UPS(Ultraviolet Photoelectron Spectroscopy) 분석을 통해 일함수를 측정하였다. 이렇게 제작된 p 타입 $Li:Cu_2O$ 박막을 이용하여 $Li:Cu_2O-ZnO$ pn 접합을 구현하고 이를 이용해 유연 나노제너레이터를 제작하였다. 다양한 특성 분석을 통해p-type을 이용한 산화물 박막 기반 유연 나노 제너레이터 특성 향상 메커니즘을 제시하였다.

• Journal of the Microelectronics and Packaging Society
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• v.19 no.1
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• pp.39-45
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• 2012

Three-dimensional integrated circuit(3D IC) technology has become increasingly important due to the demand for high system performance and functionality. In this work, BOE and HF wet etching of Cu line surfaces after CMP were conducted for Cu-Cu pattern direct bonding. Step height of Cu and $SiO_2$ as well as Cu dishing after Cu CMP were analyzed by the 3D-Profiler. Step height increased and Cu dishing decreased with increasing BOE and HF wet etching times. XPS analysis of Cu surface revealed that Cu surface oxide layer was partially removed by BOE and HF wet etching treatment. BOE treatment showed not only the effective $SiO_2$ etching but also reduced dishing and Cu surface oxide rather than HF treatment, which can be used as an meaningful process data for reliable Cu-Cu pattern bonding characteristics.

• Proceedings of the KWS Conference
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• 2000.10a
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• pp.192-195
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• 2000

This paper describes a fundamental investigation of the friction welding condition for pure copper/pure titanium and the effect of friction time, upset pressure on the mechanical and metallurgical properties of friction welding. Under the constant upset pressure, the tensile strength make a little difference with an increase in friction time. At the constant friction time, the tensile strength increased with an increase in upset pressure. The tensile fracture of Cu to Ti joint occurred in Cu base material near interface.