• 한국재료학회:학술대회논문집
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• 한국재료학회 2005년도 춘계학술발표대회 및 제8회 신소재 심포지엄 논문개요집
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• pp.72-72
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• 2005

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2004년도 ISMP Pb-free solders and the PCB technologies related to Pb-free solders
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• pp.79-92
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• 2004

RoHS compliant products are now being mass-produced. Eco-product(Pb-free+RoHS compliant+Halogen-free) will be possible from 2005. Pb-free flip chip will be qualified by 2004. 4Q. Lead Finish: SnBi-Under mass production Pd PPF-Under small production Matte Sn-will be internally qualified by 2004. 4Q Development of Pb-free Solder Ball: Stable Supply, Cost Down.

• 대한금속재료학회지
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• 제46권2호
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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.

• 마이크로전자및패키징학회지
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• 제18권2호
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• pp.49-55
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• 2011

전자기기에서의 고장 중 대부분은 작동 중 발생하는 열과 충격에 기인한다. 이 열과 충격은 PCB(Printed Board) 부품의 접합부 계면에 균열을 야기 시키고, 이 균열은 금속간 화합물(Intermetallic Compound: IMC)의 형성과 밀접한 관계를 가진다. 본 연구에서는 Sn-Ag-Cu계의 Ag함량을 변화한 Sn-1.0Ag-0.5Cu와 Sn-1.2Ag-0.5Cu 및 Sn-3.0Ag-0.5Cu의 3가지 조성의 솔더로 접합한 소재를 대상으로 1000시간 까지 등온시효(Isothermal Aging) 하였다. 등온시효 동 안 솔더(Solder)의 계면에 발생하는 IMC(Intermetallic Compound) 성장이 관찰되었으며, solder 접합부의 기계적 특성은 굽힘충격 시험법을 이용하여 평가되었다. 그 결과 시효처리 전에는 Ag 함량이 낮은 solder의 굽힘충격 특성이 우수하게 나타났으나, 시효처리 후에는 반대의 결과를 나타내었다. 이 결과는 IMC layer 주변에 생성된 미세한 $Ag_3Sn$ 및 조대한 $Cu_6Sn_5$와 관련되어, 미세한 $Ag_3Sn$이 충격을 완화한 것으로 나타나 이에 따라 굽힘충격 특성에 차이가 나타남을 알 수 있었다.

• 마이크로전자및패키징학회지
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• 제14권2호
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• pp.35-40
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• 2007

Sn-8Zn-3Bi 무연 솔더 페이스트의 접합부신뢰성 및 적합성을 평가하기 위해 유(SnPb) 무연(Sn, SnBi)도금된 Cu 리드프레임 QFP(Quad Flat Packager)를 사용하여 열충격 조건 하에서의 인장 강도의 변화 및 파괴 기구에 대한 분석을 실시하였다. 리드 도금의 종류에 상관없이 모든 시험 시편에서 열충격 사이클 수의 증가에 비례하여 접합부의 취성 특성이 강화되어 인장 강도가 감소하는 것을 확인하였다. 하지만, 접합부에는 열팽창 계수의 차이에 의해 야기될 수 있는 미세 균열은 발견되지 않았다. 단면 관찰 및 변위 이력 곡선 분석을 통하여 열충격 사이클 수의 증가에 따른 인강 강도의 감소는 접합부의 파괴 기구의 변화에 기인되었음을 확인하였다. 본 실험을 통해 Sn-3Zn-3Bi 솔더의 유 무연 도금 Cu 리드프레임과의 우수한 작업 특성과 열충격 환경 하에서도 우수한 기계적 접합 특성을 유지하는 것을 확인할 수 있었다.

• 한국주조공학회지
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• 제17권3호
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• pp.245-251
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• 1997

Solderability, interfacial reaction and mechanical properties of joint between Sn-Bi-Ag base solder and Cu-substrate were studied. Solders were subjected to aging treatments to see the change of mechanical properties for up to 30 days at $100^{\circ}C$, and then also examined the changes of microstructure and morphology of interfacial compound. Sn-Bi-Ag base solder showed about double tensile strength comparing to Pb-Sn eutectic solder. Addition of 0.7wt%Al in the Sn-Bi-Ag alloy increase spread area on Cu substrate under R-flux and helps to reduce the growth of intermetallic compound during heat-treatment. According to the aging experiments of Cu/solder joint, interfacial intermetallic compound layer was exhibited a parabolic growth to aging time. The result of EDS, it is supposed that the soldered interfacial zone was composed of $Cu_6Sn_5$.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2003년도 기술심포지움 논문집
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• pp.151-155
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• 2003

The requirements for harsh environment electronic controllers in automotive applications have been steadily becoming more and more stringent. Electronic substrate technologists have been responding to this challenge effectively in an effort to meet the performance, reliability and cost requirements. An effect of the plasma cleaning at the alumina substrate and the IMC layer between $Sn-37wt\%Pb$ solder and Ag-Pd thick film conductor after reflow soldering has been studied. Organic residual carbon layer was removed by the substrate plasma cleaning. So the interfacial adhesive strength was enhanced. As a result of AFM measurement, Ag-Pd conductor pad roughness were increased from 304nm to 330nm. $Cu_6Sn_5$ formed during initial ref]ow process at the interface between TiWN/Cu UBM and solder grew by the succeeding reflow process so the grains had a large diameter and dense interval. A cellular-shaped $Ag_3Sn$ was observed at the interface between Ag-Pd conductor pad and solder. The diameters of the $Ag_3Sn$ grains ranged from about $0.1\~0.6{\mu}m$. And a needle-shaped $Ag_3Sn$ was also observed at the inside of the solder.

• 한국재료학회지
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• 제24권3호
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• pp.166-173
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• 2014

The effects of printed circuit board electroless nickel immersion gold (ENIG) and organic solderability preservative (OSP) surface finishes on the electromigration reliability and shear strength of Sn-3.5Ag Pb-free solder bump were systematically investigated. In-situ annealing tests were performed in a scanning electron microscope chamber at 130, 150, and $170^{\circ}C$ in order to investigate the growth kinetics of intermetallic compound (IMC). Electromigration lifetime and failure modes were investigated at $150^{\circ}C$ and $1.5{\times}10^5A/cm^2$, while ball shear tests and failure mode analysis were conducted under the high-speed conditions from 10 mm/s to 3000 mm/s. The activation energy of ENIG and OSP surface finishes during annealing were evaluated as 0.84 eV and 0.94 eV, respectively. The solder bumps with ENIG surface finish showed longer electromigration lifetime than OSP surface finish. Shear strengths between ENIG and OSP were similar, and the shear energies decreased with increasing shear speed. Failure analysis showed that electrical and mechanical reliabilities were very closely related to the interfacial IMC stabilities.

• 마이크로전자및패키징학회지
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• 제15권1호
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• pp.33-37
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• 2008

Kirkendall void는 전해도금 Cu/Sn-Ag 솔더 접합부에서 형성되었으며 Cu 도금욕에 함유되는 첨가제에 의존한다. 첨가제로 사용된 SPS의 함량의 증가와 함께 $150^{\circ}C$에서 열처리 후 많은 양의 Kirkendall void가 $Cu/Cu_3Sn$ 계면에 존재하였다. AES 분석은 void 표면에 S가 편석되어 있음을 보여주었다. $Cu/Cu_3Sn$ 계면을 따라 파괴된 시편에서 Cu, Sn, S peak만 검출되었고 AES 깊이 프로파일에서 S는 급격하게 감소하였다. $Cu/Cu_3Sn$ 계면에서 S 편석은 계면에너지를 낮추고 Kirkendall void 핵생성을 위한 에너지장벽을 감소시킨다. 낙하충격시험은 SPS를 사용하여 도금된 Cu의 경우 Kirkendall void가 형성된 $Cu/Cu_3Sn$ 계면에서 파괴가 진행되고 급격하게 신뢰성이 감소됨을 보였다.

• Corrosion Science and Technology
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• 제6권2호
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• pp.50-55
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• 2007

The smaller size and higher integration of advanced electronic package systems result in severe electrochemical reliability issues in microelectronic packaging due to higher electric field under high temperature and humidity conditions. Under these harsh conditions, electronic components respond to applied voltages by electrochemical ionization of metal and the formation of a filament, which leads to short-circuit failure of an electronic component, which is termed electrochemical migration. This work aims to evaluate electrochemical migration susceptibility of the pure Sn, Sn-3.5Ag, Sn-3.0Ag-0.5Cu solder alloys in $Na_{2}SO_{4}$. The water drop test was performed to understand the failure mechanism in a pad patterned solder alloy. The polarization test and anodic dissolution test were performed, and ionic species and concentration were analyzed. Ag and Cu additions increased the time to failure of Pb-free solder in 0.001 wt% $Na_{2}SO_{4}$ solution at room temperature and the dendrite was mainly composed of Sn regardless of the solders. In the case of SnAg solders, when Ag and Cu added to the solders, Ag and Cu improved the passivation behavior and pitting corrosion resistance and formed inert intermetallic compounds and thus the dissolution of Ag and Cu was suppressed; only Sn was dissolved. If ionic species is mainly Sn ion, dissolution content than cathodic deposition efficiency will affect the composition of the dendrite. Therefore, Ag and Cu additions improve the electrochemical migration resistance of SnAg and SnAgCu solders.