• 한국재료학회:학술대회논문집
• /
• 한국재료학회 1996년도 재료학회 추계학술발표회
• /
• pp.83-83
• /
• 1996

• 한국마이크로전자및패키징학회:학술대회논문집
• /
• 한국마이크로전자및패키징학회 2002년도 추계기술심포지움논문집
• /
• pp.49-53
• /
• 2002

The Sn-Cu eutectic solder bump formation ($140{\mu}{\textrm}{m}$ diameter, $250{\mu}{\textrm}{m}$ pitch) by electroplating was studied for flip chip package fabrication. The effect of current density and plating time on Sn-Cu deposit was investigated. The morphology and composition of plated solder surface was examined by scanning electron microscopy. The plating thickness increased with increasing time. The plating rate increased generally according to current density. After the characteristics of Sn-Cu plating were investigated, Sn-Cu solder bumps were fabricated on optimal condition of 5A/dm$^2$, 2hrs. Ball shear test after reflow was performed to measure adhesion strength between solder bump and UBM (Under Bump Metallization). The shear strength of Sn-Cu bump after reflow was higher than that of before reflow.

• 마이크로전자및패키징학회지
• /
• 제14권4호
• /
• pp.71-77
• /
• 2007

본 연구에서는 리플로우 횟수를 달리하여 Sn-37Pb, Sn-3.5Ag와 Sn-3.5Ag-0.75Cu (all wt.%) BGA 솔더 접합부들을 OSP가 코팅된 Cu 패드 상에 형성시킨 후, 기계적 전기적 특성을 연구하였다. 주사전자현미경 분석 결과, 접합 계면에 생성된 $Cu_6Sn_5$ 금속간화합물 층의 두께는 리플로우 횟수가 증가함에 따라 증가하였다. Sn-Pb와 Sn-Ag-Cu 솔더 접합부의 경우, 3회 리플로우 후 최대 전단 강도를 나타내었으며, Sn-Ag 솔더 접합부의 경우 4회 리플로우 후 최대 전단 강도를 나타내었다. 이후 리플로우 횟수가 10회까지 증가함에 따라 전단 강도는 점차 감소하였다. 리플로우 횟수가 증가함에 따라 전기적 특성은 점차 감소하였다.

• 대한금속재료학회지
• /
• 제48권11호
• /
• pp.1041-1046
• /
• 2010

The reactions between a Sn-3.0Ag-0.5Cu solder alloy and electroless Ni/electroless Pd/immersion Au (ENEPIG) surface finishes with various Pd layer thicknesses (0, 0.05, 0.1, 0.2, $0.4{\mu}m$) were examined for the effect of the Pd layer on the massive spalling of the $(Cu,Ni)_6Sn_5$ layer during reflow at $235^{\circ}C$. The thin layer deposition of an electroless Pd (EP) between the electroless Ni ($7{\mu}m$) and immersion Au ($0.06{\mu}m$) plating on the Cu substrate significantly retarded the massive spalling of the $(Cu,Ni)_6Sn_5$ layer during reflow. Its retarding effect increased with an increasing EP layer thickness. When the EP layer was thin (${\leq}0.1{\mu}m$), the retardation of the massive spalling was attributed to a reduced growth rate of the $(Cu,Ni)_6Sn_5$ layer and thus to a lowered consumption rate of Cu in the bulk solder during reflow. However, when the EP layer was thick (${\geq}0.2{\mu}m$), the initially dissolved Pd atoms in the molten solder resettled as $(Pd,Ni)Sn_4$ precipitates near the solder/$(Cu,Ni)_6Sn_5$ interface with an increasing reflow time. Since the Pd resettlement requires a continuous Ni supply across the $(Cu,Ni)_6Sn_5$ layer from the Ni(P) substrate, it suppressed the formation of $(Ni,Cu)_3Sn_4$ at the $(Cu,Ni)_6Sn_5/Ni(P)$ interface and retarded the massive spalling of the $(Cu,Ni)_6Sn_5$ layer.

• 마이크로전자및패키징학회지
• /
• 제19권1호
• /
• pp.47-53
• /
• 2012

무연 리플로우 공정 횟수에 따른 organic solderability preservative(OSP) 표면처리 두께변화 및 열화현상을 분석하였다. 무연솔더 접합부의 접합강도에 미치는 OSP 표면처리의 열화특성을 SnPb 표면처리 경우와 비교하여 조사하였다. 또한 리플로우 pass에 따른 무연솔더 접합강도 열화분석을 위해 OSP 및 SnPb 표면처리된 FR-4 재질 PCB를 각각 1-6회 리플로우 처리하였다. 이후 각 리플로우를 거친 PCB 위에 2012 칩 저항기를 실장한 후 접합강도 변화를 측정하였다. 그 결과, 리플로우 공정 중 열 노출에 의해 OSP 코팅두께가 감소되는 것이 관찰되었고, 코팅두께의 변화 및 OSP 코팅 층의 산화를 유발함으로써, 솔더의 젖음성이 감소될 수 있음을 확인할 수 있었다. OSP 열화에 따른 솔더 접합강도는 SnPb 표리처리시 평균 62.2 N 이였으며, OSP의 경우는 약 58.1 N 이였다. 리플로우 공정 노출에 따라 OSP 코팅 층은 열분해 되지만, 솔더 접합부의 접합강도 측면에서는 산업적으로 적용 가능성을 확인할 수 있었다.

• 마이크로전자및패키징학회지
• /
• 제15권4호
• /
• pp.1-7
• /
• 2008

본 실험에서는 두가지 리플로 시스템에 따라 솔더 범프 내에 생성되는 금속간 화합물의 성장거동에 대하여 연구하였다. 산화막이 증착된 Si 기판 위에 직류 마그네트론 스퍼터링을 이용하여 Ti(50 nm), Cu($1{\mu}m$), Au(50 nm), Ti(50 nm)의 박막을 형성한 후, 전해 도금을 이용하여 $5{\mu}m$두께의 Cu 범프와 $20{\mu}m$ 두께의 Sn 범프를 형성하였다. 급속열처리장치(RTA)와 일반 리플로를 이용하여 전해 도금으로 형성된 Sn($20{\mu}m$)/Cu($5{\mu}m$) 범프를 동일한 온도에서 각각 리플로 공정을 진행한 결과, 급속열처리장치를 이용하여 리플로를 할 때, 플럭스를 사용하지 않고 범프로 형성할 수 있었으며, 솔더 계면에 형성된 금속간 화합물이 일반 리플로의 경우보다 더 얇게 형성되었다.

• 마이크로전자및패키징학회지
• /
• 제17권1호
• /
• pp.1-7
• /
• 2010

본 연구에서는 $430^{\circ}C$에서 Bi-10Cu-20Sb-0.3Ni 조성의 솔더 합금과 Cu간의 리플로루 솔더링 시 생성되는 계면 반응층을 분석하였고, 솔더링 시간에 따른 계면 반응층의 성장 속도를 측정하였다. 리플로우 솔더링 후 Bi-10Cu-20Sb-0.3Ni/Cu의 계면 반응층을 분석한 결과, $(Cu,Ni)_2Sb$ 및 $Cu_4Sb$ 금속간 화합물층, 그리고 Bi 조성과 $Cu_4Sb$ 상이 주기적으로 존재하는 아지랑이 형상층이 연속적으로 생성되었다. 또한 120 s까지의 솔더링 시간 영역에서는 계면 반응층의 총 두께가 솔더링 시간에 대해 직선적으로 증가하는 경향이 관찰되었다. 합금원소로 첨가된 Ni은 가장 두꺼운 $Cu_4Sb$ 반응층의 형성에 참여하지 않아 계면 금속간 화합물의 성장 속도를 억제시키는 작용을 나타내지 못했다.

• 한국주조공학회지
• /
• 제22권1호
• /
• pp.35-41
• /
• 2002

To improve the reliability of solder joints, a composite solder which consists of solder matrix and intermetallic reinforcements was manufactured by a new method. The cast ingot of Sn-6.9Cu-2.9Ag alloy had primary Cu6Sn5 intermetallics in the form of dendrites. After rolling the ingot, the intermetallic dendrites were crushed into fine particles and distributed uniformly throughout the solder matrix. As the rolled strips became thinner, the average size of the crushed particles reached a critical size which did not decrease any more by further rolling. The critical size was nearly the same as the average width of intermetallic dendrite trunk. The crushed intermetallic particles did not melt and remained in solid state during reflow soldering due to their high meltingterm-perature. The coarsening and gravitational segregation of the particles were observed during reflow soldering.

• 한국표면공학회지
• /
• 제35권1호
• /
• pp.47-52
• /
• 2002

Intermetallic compound on the soldered interface plays important role on the bondability and mechanical properties of soldered joint. The formation of intermetallic compounds are influenced by many factors such as temperature, holding time, base metals and so on. On this study the effect of number of reflow times on the intermetallic growth was investigated. For the experimental materials, Sn-3.5Ag-0.7Cu solder ball of 0.3mm diameter and RMA-type flux were used. Thickness of intermetallic compound of solder ball by 2nd reflow showed nearly 60% higher than that of 1st reflow, and shear strength showed 10% higher value. Thickness and shear strength according to the position of interface such as upper side or lower side between two substrates were also investigated.

• 한국표면공학회지
• /
• 제36권5호
• /
• pp.373-378
• /
• 2003

With increasing environmental concerns, application of lead-free solder and fluxless soldering process have been taken attention from the electronic packaging industry. Plasma treatment is one of the soldering methods for the fluxless soldering, and it can prevent environmental pollution cased by flux. On this study fluxless soldering process under $Ar-H_2$plasma using lead free solders such as Sn-3.5 wt%Ag, Sn-3.5 wt%Ag-0.7 wt%Cu and Sn-37%Pb for a reference was investigated. As the plasma reflow has higher soldering temperature than normal air reflow, the effects of UBM(Under Bump Metallization) thickness on the interfacial reaction and bonding strength can be critical. Experimental results showed in case of the thin UBM, Au(20 nm)/Cu(0.3 $\mu\textrm{m}$)/Ni(0.4 $\mu\textrm{m}$)/Al(0.4 $\mu\textrm{m}$), shear strength of the soldered joint was relatively low as 19-27㎫, and it's caused by the crack observed along the bonded interface. The crack was believed to be produced by the exhaustion of the thin UBM-layer due to the excessive reaction with solder under plasma. However, in case of thick UBM, Au(20 nm)/Cu(4 $\mu\textrm{m}$)/Ni(4 $\mu\textrm{m}$)/Al(0.4 $\mu\textrm{m}$), the bonded interface was sound without any crack and shear strength gives 32∼42㎫. Thus, by increasing UBM thickness in this study the shear strength can be improved to 50∼70%. Fluxed reflow soldering under hot air was also carried out for a reference, and the shear strength was 48∼52㎫. Consequently the fluxless soldering with plasma showed around 65∼80% as those of fluxed air reflow, and the possibility of the $Ar-H_2$ plasma reflow was evaluated.