• Proceedings of the KWS Conference
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• 2010.05a
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• pp.77-77
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• 2010

본 연구에서는 Sn-3.0Ag-0.5Cu (SAC305) 무연솔더의 최적 인쇄성을 위한 PCB 및 마스크설계, 스크린프린팅 공정변수의 최적값을 실험계획법을 통해 평가하였다. 사용된 칩은 가로 0.4mm 세로 0.2mm의 0402 MLCC칩이며, 사용된 시험보드는 OSP 표면처리된 PCB이었다. 인쇄성을 판단하기 위한 공정인자는 금속마스크 두께, 마스크홀 크기, 패드크기 및 모양, 인쇄각도, 인쇄속도, 판분리속도이었다. ANOVA분석을 통해 주인자를 파악하였으며, 인쇄성에 영향을 미치는 주인자는 마스크두께와 인쇄각도임이 확인되었다. 그 후 중심 합성법을 이용하여 인쇄성 최적 조건을 확인하였다. 결과로 나타난 등고선/표면도를 통해, 마스크두께가 작을 때에는 인쇄각도가 작아야 높은 인쇄성을 갖으며, 또한 마스크 두께가 클 경우에는 인쇄각도가 커야 높은 인쇄성을 가짐을 알 수 있었다. 추가실험을 통해서 인쇄성 표면도의 정확도를 확인하였으며, 실험값은 표면도에서 표시된 인쇄성값과 비슷함을 알 수 있었다. 또한, 인쇄성이 낮은 영역과 높은 영역에서 접합강도값을 측정하였으며, 인쇄성이 좋은 영역에서 접합강도도 높음을 알 수 있었다.

• Journal of Welding and Joining
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• v.27 no.1
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• pp.85-89
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• 2009

Reflow process conditions were investigated for 0402 electric parts with Sn-3.0Ag-0.5Cu solders. Circle hole shape metal mask with 100 m thickness showed excellent printability. Self alignment abilities were 71% for 1005 chips, 52% for 0603 chips, and 3% for 0402 chips. Average joining strengos were 1990 gf for 1005 chips, 867 gf for 0603 chips, and 525 gf for 0402 chips. As mis-mounting angle increased, joining strength decreased. Considering self-alignment ability, mounting angle had to be under $5^{\circ}$ and contact area of the chips had to be over 40% for Pb-free soldering process for 0402 chips.

• Journal of the Mineralogical Society of Korea
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• v.24 no.3
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• pp.245-252
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• 2011

콜롬비아는 안데스 산맥의 북단에 위치하며 NS 방향의 단층대를 기준으로 지질 환경의 차이가 크다. 단층대를 기준으로 동부지역은 원생대 변성암류와 이를 피복하는 고생대 변성퇴적암류가 주로 분포하며, 서부 지역은 고생대 퇴적암류, 중생대 화성암류, 제 3 기 화산양류 및 퇴적암류가 주로 분포한다. 지화학이상대는 6개 그룹으로 분류되며, 철 (Fe), 귀금속(Au, Ag, Pt), 기초금속(Cu, Pb, Zn), 희유금속(Sn, Cr, Co, Mn, Mo, Ni, Nb, W, V, Mg, Ti, Be, REE, Ga, Zr, Hf, Se, Te, Ta, Cd, In, Li 등) 빛 핵원료자원인 U 이상대로 구성된다. 콜롬비아의 주요 부존자원은 석탄, 니켈, 금 및 에메랄드이다. 에메랄드, 석탄 및 니켈은 세계적인 매장규모와 생산량을 보인다. 콜롬비아는 탐사가 거의 수행되지 않은 지역이 전 국토의 49%에 달해 광물부존 잠재성은 현재보다 크게 높을 것으로 보인다. 따라서 최근 콜롬비아와의 광물자원 협력이 강화되고 있는 시점에서 미탐사 지역을 대상한 공동탐사를 지화학 이상대가 확인된 지역을 중심으로 수행하여 신규광체를 확보하고, 광물자원 협력을 강화함으로써 공동개발 여건을 마련할 필요가 있다고 판단된다.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.6
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• pp.90-96
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• 2011

In this study, the characteristic of fractured portion and shape on solder joints were investigated according to the thermal shock test for Automotive Application Component using Sn-3.0Ag-0.5Cu solder, which has a outstanding property as Lead-free solder. The value of pull and shear strength was decreased in principle after 432 cycles thermal shock test. In addition, fracture mode was verified by using EDS and SEM to observe fractured shape on the solder joints before and after thermal shock. In before thermal shock test, the fracture mode revealed typically solder layer's fracture mode. In after thermal shock test, we identified multiple fracture mode of the ductile and brittle fracture. Even though same composition of solder was used to experimental for estimating. the fracture mode varied on the fracture portion's height and the directional angles of shear strength. In conclusion, we identified that mechanical strength was affected on the solder layer's fracture mode.

• Journal of Welding and Joining
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• v.17 no.3
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• pp.90-95
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• 1999

The increase in high speed, multi-function and high I/O pin semiconductor devices highly demands high pin count, very thin, and high density packages. BGA is one of the solutions, but the package has demerits in package reliability, surface mounting problems due to the PCB warpage and solder joint crack related with TCE mismatch between the materials. On this study to verify the thermal fatigue lifetime of the solder joint FEM and experiments were performed after surface mounting BGA with different solder composition and reliability conditions. FEM showed optimum composition of Ag3.2-Sn96.5 and under the composition minimum creep deformation of the solder joint was calculated, and the thermal fatigue lifetime was improved. In view of temperature cycle condition, the conditions of $-65^{\circ}C$to $150^{\circ}C$ showed minimum lifetime and t was 1/3 of $0^{\circ}C$ to $125^{\circ}C$ condition. Test board was prepared and solder joint crack was verified. Until 1000cycle on soder joint crack was observed.

• Journal of Surface Science and Engineering
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• v.39 no.6
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• pp.302-311
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• 2006

Nowadays the open-type lead-acid battery for vehicle use is being replaced with the sealed-type because it needs no maintenance and has a longer cycle life. Thus researches on this battery are being conducted very actively by many advanced battery companies. There is, however, a serious problem with the maintenance free(MF) battery that its cathode electrode has a limited cycle life due to a corrosion of grid. In this study, it was aimed to improve a corrosion resistance of the cathode grid which is commonly made of Pb-Ca alloy for a mechanical strength. For this purpose, various amounts of alloying elements such as Sn, Ag and Ba were added singly or together to the Pb-Ca alloys and investigated their corrosion behaviors. Batteries fabricated by using these alloys as cathode grids were subjected to life cycle test and their corrosion layers appeared at the interface between the grids and the active materials were carefully observed in order to clarify effects of alloying elements.

• ETRI Journal
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• v.35 no.4
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• pp.625-631
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• 2013

For the formation of solder bumps with a fine pitch of 130 ${\mu}m$ on a printed circuit board substrate, low-volume solder on pad (LVSoP) technology using a maskless method is developed for SAC305 solder with a high melting temperature of $220^{\circ}C$. The solder bump maker (SBM) paste and its process are quantitatively optimized to obtain a uniform solder bump height, which is almost equal to the height of the solder resist. For an understanding of chemorheological phenomena of SBM paste, differential scanning calorimetry, viscosity measurement, and physical flowing of SBM paste are precisely characterized and observed during LVSoP processing. The average height of the solder bumps and their maximum and minimum values are 14.7 ${\mu}m$, 18.3 ${\mu}m$, and 12.0 ${\mu}m$, respectively. It is expected that maskless LVSoP technology can be effectively used for a fine-pitch interconnection of a Cu pillar in the semiconductor packaging field.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.9-15
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• 2018

This paper shows the principles and characteristics of the transient liquid phase (TLP) bonding technology for power modules packaging. The power module is semiconductor parts that change and manage power entering electronic devices, and demand is increasing due to the advent of the fourth industrial revolution. Higher operation temperatures and increasing current density are important for the performance of power modules. Conventional power modules using Si chip have reached the limit of theoretical performance development. In addition, their efficiency is reduced at high temperature because of the low properties of Si. Therefore, Si is changed to silicon carbide (SiC) and gallium nitride (GaN). Various methods of bonding have been studied, like Ag sintering and Sn-Au solder, to keep up with the development of chips, one of which is TLP bonding. TLP bonding has the advantages in price and junction temperature over other technologies. In this paper, TLP bonding using various materials and methods is introduced. In addition, new TLP technologies that are combined with other technologies such as metal powder mixing and ultrasonic technology are also reviewed.

• Korean Journal of Metals and Materials
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• v.46 no.2
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• pp.80-87
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• 2008

Many researches related to the reliability of Pb-free solder joints with PCB (printed circuit board) surface finish under thermal or vibration stresses are in progress, because the electronics is operating in hash environment. Therefore, it is necessary to assess Pb-free solder joints life with PCB surface finish under thermal and mechanical stresses. We have investigated 4-points bending fatigue lifetime of Pb-free solder joints with OSP (organic solderability preservative) and ENIG (electroless nickel and immersion gold) surface finish. To predict the bending fatigue life of Sn-3.0Ag-0.5Cu solder joints, we use the test coupons mounted 192 BGA (ball grid array) package to be added the thermal stress by conducting thermal shock test, 500, 1,000, 1,500 and 2,000 cycles, respectively. An 4-point bending test is performed in force controlling mode. It is considered that as a failure when the resistance of daisy-chain circuit of test coupons reaches more than $1,000{\Omega}$. Finally, we obtained the solder joints fatigue life with OSP and ENIG surface finish using by Weibull probability distribution.

• Economic and Environmental Geology
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• v.42 no.3
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• pp.177-193
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• 2009

The Samgwang deposit consists of eight massive mesothermal quartz veins that filled NE and NW-striking fractures along fault zones in Precambrian granitic gneiss of the Gyeonggi massif. The mineralogy and paragenesis of the veins allow two separate discrete mineralization episodes(stage I=quartz and calcite stage, stage II-calcite stage) to be recognized, temporally separated by a major faulting event. The ore minerals are contained within quartz and calcite associated with fracturing and healing of veins that occurred during both mineralization episodes. The hydrothermal alteration of stage I is sericitization, chloritization, carbonitization, pyritization, silicification and argillization. Sericitic zone occurs near and at quartz vein and include mainly sericite, quartz, and minor illite, carbonates and chlorite. Chloritic zone occurs far from quartz vein and is composed of mainly chlorite, quartz and minor sericite, carbonates and epidote. Fe/(Fe+Mg) ratios of sericite and chlorite range 0.45 to 0.50(0.48$\pm$0.02) and 0.74 to 0.81(0.77$\pm$0.03), and belong to muscovite-petzite series and brunsvigite, respectiveIy. Calculated $Al_{IV}$-FE/(FE+Mg) diagrams of sericite and chlorite suggest that this can be a reliable indicator of alteration temperature in Au-Ag deposits. Calculated activities of chlorite end member are $a3(Fe_5Al_2Si_3O_{10}(OH)_6$=0.0275${\sim}$0.0413, $a2(Mg_5Al_2Si_3O_{10}(OH)_6$=1.18E-10${\sim}$7.79E-7, $a1(Mg_6Si_4O_{10}(OH)_6$=4.92E-10${\sim}$9.29E-7. It suggest that chlorite from the Samgwang deposit is iron-rich chlorite formed due to decreasing temperature from high temperature(T>450$^{\circ}C$). Calculated ${\alpha}Na^+$, ${\alpha}K^+$, ${\alpha}Ca^{2+}$, ${\alpha}Mg^{2+}$ and pH values during wallrock alteration are 0.0476($400^{\circ}C$), 0.0863($350^{\circ}C$), 0.0154($400^{\circ}C$), 0.0231($350^{\circ}C$), 2.42E-11($400^{\circ}C$), 7.07E-10($350^{\circ}C$), 1.59E-12($400^{\circ}C$), 1.77E-11($350^{\circ}C$), 5.4${\sim}$6.4($400^{\circ}C$), 5.3${\sim}$5.7($350^{\circ}C$)respectively. Gain elements(enrichment elements) during wallrock alteration are $TiO_2$, $Fe_2O_3(T)$,CaO, MnO, MgO, As, Ag, Cu, Zn, Ni, Co, W, V, Br, Cs, Rb, Sc, Bi, Nb, Sb, Se, Sn and Lu. Elements(Ag, As, Zn, Sc, Sb, Rb, S, $CO_2$) represents a potential tools for exploration in mesothermal and epithermal gold-silver deposits.