• 마이크로전자및패키징학회지
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• 제18권1호
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• pp.35-39
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• 2011

고속전단시힘의 표준화를 위한 기초 연구의 일부로 Sn-3.0wt%Ag-0.5wt%Cu 솔더 볼의 고속전단특성에 대한 연구를 수행 하였다. 고속전단 시험편 제작을 위해 직경 450 ${\mu}m$의 솔더 볼을 FR4 PCB (Printed Circuit Board) 위에 장착한 후 $245^{\circ}C$ 온도에서 리플로 솔더링을 행하였다. PCB 상의 금속 패드로는 ENIG (Electroless Nickel/mmersion Gold, i.e Cu/Ni/Au)와 OSP (Organic Solderability Preservative, Cu 패드)를 사용하였다. 고속전단 속도는 0.5~3.0 m/s 범위, 전단 팁의 높이는 10~135 ${\mu}m$ 범위에서 변화시켰다. 실험결과로서, OSP 패드의 경우 전단 팁 높이 증가에 따라 연성 파괴가 증가하였으며, 전단속도 증가에 따라 연성파괴는 감소되었다. ENIG 패드의 경우에도 전단 팁 높이 증가에 따라 연성 파괴가 증가하였다. 전단 팁 높이 10 ${\mu}m$(볼 직경의 2%)는 패드 박리 파괴가 대부분이어서 전단파면 관찰에는 부적절한 높이였다. 고속전단에너지는 OSP 및 ENIG 패드 모두 전단 팁 높이 증가에 따라 증가하는 경향을 보였다.

• 마이크로전자및패키징학회지
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• 제16권3호
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• pp.11-17
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• 2009

휴대폰 및 휴대기기의 낙하 충격에 대한 관심이 증가되고 있는 상황에서 솔더 볼 접합부의 낙하 충격특성은 패드의 종류와 리플로우 횟수에 영향을 받게 되어 이에 따른 신뢰성 평가가 요구된다. 이와 관련한 평 가법으로 일반적으로는 JEDEC에서 제정한 낙하충격 시험법을 사용하고 있으나 이 방법은 고 비용과 장시간이 소모되는 문제가 있어 본 연구에서는 낙하충격 특성을 간접적으로 평가하는 시험항목인 고속 전단시험을 실시하여 리플로우 횟수에 의해 성장하는 금속간 화합물 층과 OSP(Organic Solderability Preservative), ENIG(Electroless Nickel Immersion Gold) 및 ENEPIG(Electroless Nickel Electroless Palladium Immersion Gold) 등 표면처리에 따른 고속 전단특성을 비교, 분석하였다. 그 결과 리플로우 횟수가 증가함에 따라 IMC 층의 성장으로 고속 전단강도와 충격 에너지 값은 점차 감소하였다. 리플로우 횟수가 1회일 때는 ENEPIG, ENIG, OSP 순으로 고속 전단강도와 충격 에너지 값이 높았고 8회일 때는 ENEPIG, OSP, ENIG 순으로 충격 에너지 값이 높게 측정되었다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2013년도 춘계학술대회 논문집
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• pp.126-127
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• 2013

기존 PCB의 Surface treatment 방식으로 널리 행하고 있는 ENIG 공정은 고가의 Au에 따른 원가 상승으로 인해 가격 경쟁력이 떨어지고 있는 실정이다. 이를 개선하고자, 기존의 Au 공정을 Ag 공정으로 대체하였으며, 그 결과 Ball Wettability 특성 1.8mm (0.76mm ball)과 Solder 접합강도 (19N)의 특징을 확보하였다.

• 마이크로전자및패키징학회지
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• 제17권1호
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• pp.55-61
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• 2010

본 연구에서는 무연솔더볼 접합부의 신뢰성평가를 위해 굽힘충격 시험법을 사용하였다. 시험 방법의 표준화를 위하여 시험 시의 주파수, +/-진폭의 크기 등을 각각 변화하여 가면서 각 조건이 결과치에 미치는 영향을 분석하고 굽힘충격 시험을 위한 최적조건을 도출하였다. 굽힘충격 시험을 위한 최적조건은 주파수 10 Hz, 진폭은 (+12/-1)~(+15/-1)의 범위이었다. 시험에 사용된 PCB 표면처리는 Cu-OSP(Organic Solderability Preservative)와 ENIG(Electroless Nickel Immersion Gold) 및 ENEPIG(Electroless Nickel, Electroless Palladium, Immersion Gold)의 3종류를 사용하였고, 솔더 접합계면과 파단면을 관찰한 결과 Cu-OSP와 ENIG의 경우 금속간 화합물 층을 따라서 균열이 발생하여 파단이 일어났으나, ENEPIG의 경우에는 주로 솔더 영역에서만 균열이 생성되고 성장하였다.

• 대한금속재료학회지
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• 제49권3호
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• pp.237-242
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• 2011

The effect of shearing speed on the shear force and energy of Sn-0Ag-0.5Cu solder ball was investigated. Various UBM (under bump metallurgy)'s on Cu pads were used such as ENEPIG (Electroless Nickel, Electroless Palladium, Immersion Gold; Ni/Pd/Au), ENIG (Electroless Nickel, Immersion Gold; Ni/Au), OSP (Organic Solderability Preservative). To fabricate a shear test specimen, a solder ball, $300{\mu}m$ in diameter, was soldered on a pad of FR4 PCB (printed circuit board) by a reflow soldering machine at $245^{\circ}C$. The solder bump on the PCB was shear tested by changing the shearing speed from 0.01 m/s to 3.0 m/s. As experimental results, the shear force increased with a shearing speed of up to 0.6 m/s for the ENIG and the OSP pads, and up to 0 m/s for the ENEPIG pad. The shear energy increased with a shearing speed up to 0.3 m/s for the ENIG and the OSP pads, and up to 0.6 m/s for the ENEPIG pad. With a high shear speed of over 0 m/s, the ENEPIG showed a higher shear force and energy than those of the ENIG and OSP. The fracture surfaces of the shear tested specimens were analyzed, and the fracture modes were found to have closer relationship with the shear energy than the shear force.

• 대한금속재료학회지
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• 제49권8호
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• pp.635-641
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• 2011

The effect of high shear speed on shear force, shear energy and fracture surface was investigated for the solder joint of a $Sn-_{3.0}Ag-_{0.5}Cu$ ball. For both ENIG and OSP pads, the shear force increased with an increase in shearing speed to 0.3 m/s. However, for an ENEPIG pad, the shear force increased with an increase in shear speed to 0.6 m/s and kept almost constant afterward. The shear energy decreased with an increase in shearing speed for ENIG and OSP pads. For the ENEPIG pad, however, the shear energy almost remained constant in a shearing speed range 0.3-3.0 m/s. The fracture mode analysis revealed that the amount of brittle fracture for the ENIG and the OSP pads increased with shearing speed, and a complete brittle fracture appeared at 1.0 m/s for ENIG and 2.0 m/s for OSP. However, the ENEPIG pad showed only a ductile fracture until 0.25 m/s, and a full brittle fracture didn't occur up to 3.0 m/s. The fracture mode matched well with the shear energy. The results from the high speed shear test of SAC305 were similar to those of SAC105.

• 한국표면공학회지
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• 제40권1호
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• pp.32-38
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• 2007

Ni coating layers were formed using a newly developed electroless Ni plating solution. The properties of Ni coating layer such as internal stress, hardness, surface roughness, crystallinity, solderability and surface morphology were investigated using various tools. Results revealed that internal stress decreased with plating time and reached $40N/mm^2$ at 20 minutes of the plating time. Hardness increased with increasing P content and thickness. Surface roughness of the pad decreased with Ni and Ni/Au plating. Crystallinity decreased with increasing P content. Solderability based on wettability decreased with Ni and Ni/Au plating. Based on surface morphology, it is expected that Ni coating layer formed using a newly developed electroless Ni plating solution is lower than that formed using a commercial electroless Ni plating solution in possibility of black pad occurrence.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2005년도 추계학술발표대회 개요집
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• pp.219-221
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• 2005

Sn-9Zn solder balls were bonded to Cu, ENIG (Electroless Nickel/Immersion Gold) and electrolytic Au/Ni pads, and the effect of aging on their joint reliability was investigated. The interfacial products were different from the general reaction layer formed in a Sn-base solder. The intermetallic compounds formed in the solder/Cu joint were $Cu_{5}Zn_{8}$ and $Cu_{6}Sn_{5}$. After aging treatment, voids formed irregularly at the bottom side of the solder because of Sn diffusion into the $Cu_{5}Zn_{8}$ IMC. In the case of the solder/ENIG joint, $AuZn_{3}$ IMCs were formed at the interface. In the case of the Au/Ni/Cu substrate, an $AuZn_{3}$ IMC layer formed at the interface due to the fast reaction between Au and Zn. In addition, the $AuZn_{3}$ IMC layer became detached from the interface after reflow. When the aging time was extended to 100 h, $Ni_{5}Zn_{21}$ IMC was observed on the Ni substrate.

• 한국표면공학회지
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• 제43권3호
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• pp.142-147
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• 2010

We evaluated characteristics of ENEPIG (Electroless Nickel Electroless Palladium Immersion Gold) surface treatment for mobile equipment that requires high reliability, in addition to investigating surface treatment processes for semiconductor boards that require high reliability such as regular PCB-package systems, board-on-chip, chip-scaled package (CSP), etc and application for semiconductor package board of SIP, BOC. As a result, it appeared that ENEPIG has superior properties compared to ENIG surface treatment in corrosion resistance, solder junction, wetting, etc. We anticipate that these results will be able to lend credibility to ENEPIG as a low-cost alternative for producing mobile devices such as the cell phones, especially when applied to mass production.

• 한국전기전자재료학회논문지
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• 제23권6호
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• pp.481-486
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• 2010

ENIG (electroless Ni immersion gold) is one of surface finishing which has been most widely used in fine pitch SMT (surface mount technology) and BGA (ball grid array) packaging process. The reliability for package bondability is mainly affected by interfacial reaction between solder and surface finishing. Since the behavior of IMC (intermetallic compound), or the interfacial reaction between Ni and solder, affects to some product reliabilities such as solderability and bondability, understanding behavior of IMC should be important issue. Thus, we studied the properties of ENIG with P contents (9 wt% and 13 wt%), where the P contents is one of main factors in formation of IMC layer. The effect of P content was discussed using the results obtained from FE-SEM(field-emission scanning electron microscope), EPMA(electron probe micro analyzer), EDS(energy dispersive spectroscopy) and Dual-FIB(focused ion beam). Especially, we observed needle type irregular IMC layer with decreasing Ni contents under high P contents (13 wt%). Also, we found how IMC layer affects to bondability with forming continuous Kirkendall voids and thick P-rich layer.