• Journal of Welding and Joining
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• 제21권5호
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• pp.534-539
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• 2003

An efficient soldering process using the longitudinal ultrasonic vibration is introduced in this work for electronic packaging. The effects of the process parameters such as the ultrasonic frequency, amplitude, dimension of the metal bump and solder are analyzed through a viscoelastic lumped model. The viscoelastic properties of the eutectic solder were measured for calculation and evaluation of heat generation capability of the solder. Experiments were conducted to verify the possibility of the proposed ultrasonic soldering method by inserting the Cu and Au bumps into the solder block. Localized heating due to ultrasonic vibration melts the solder near the metal bump, which demonstrates the applicability of the ultrasonic soldering method to the high-density electronic packaging.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 춘계 기술심포지움 논문집
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• pp.85-91
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• 2002

Even though electroless Hi and Sn-Ag-Cu solder are widely used materials in electronic packaging applications, interfacial reactions of the ternary Ni-Cu~Sn system have not been known well because of their complexity. Because the growth of intermetallics at the interface affects reliability of solder joint, the intermetallics in Ni-Cu-Sn system should be identified, and their growth should be investigated. Therefore, in present study, interfacial reactions between electroless Ni UB7f and 95.5Sn-4.0Ag-0.5Cu alloy were investigated focusing on morphology of the IMCs, thermodynamics, and growth kinetics. The IMCs that appear during a reflow and an aging are different each other. In early stage of a reflow, ternary IMC whose composition is Ni$_{22}$Cu$_{29}$Sn$_{49}$ forms firstly. Due to the lack of Cu diffusion, Ni$_{34}$Cu$_{6}$Sn$_{60}$ phase begins growing in a further reflow. Finally, the Ni$_{22}$Cu$_{29}$Sn$_{49}$ IMC grows abnormally and spalls into the molten solder. The transition of the IMCs from Ni$_{22}$Cu$_{29}$Sn$_{49}$ to Ni$_{34}$Cu$_{6}$Sn$_{60}$ was observed at a specific temperature. From the measurement of activation energy of each IMC, growth kinetics was discussed. In contrast to the reflow, three kinds of IMCs (Ni$_{22}$Cu$_{29}$Sn$_{49}$, Ni$_{20}$Cu$_{28}$Au$_{5}$, and Ni$_{34}$Cu$_{6}$Sn$_{60}$) were observed in order during an aging. All of the IMCs were well attached on UBM. Au in the quaternary IMC, which originates from immersion Au plating, prevents abnormal growth and separation of the IMC. Growth of each IMC is very dependent to the aging temperature because of its high activation energy. Besides the IMCs at the interface, plate-like Ag3Sn IMC grows as solder bump size inside solder bump. The abnormally grown Ni$_{22}$Cu$_{29}$Sn$_{49}$ and Ag$_3$Sn IMCs can be origins of brittle failure.failure.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 1999년도 1st Korea-Japan Advanced Semiconductor Packaging Technology Seminar
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• pp.127-154
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• 1999

Interconnect - Wire bonding-> Flip chip interconnect ; At research step, Au stud bump bonding seems to be more proper .Package -Plastic package-> $Z_{0}$ controlled land grid package -Flip Chip will be used for RF ICs and CSP for digital ICs -RF MCM comprised of bare active devices and integrated passive components -Electrical design skills are much more required in RF packaging .Passive Component -discrete-> integrated -Both of size and numbers of passive components must be reduced

• 한국전기전자재료학회논문지
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• 제22권3호
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• pp.199-204
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• 2009

The effect of temperature on ACF thermocompression bonding for FPD assembly was investigated, It was found that Au bumps on driver IC's were not bonded to the glass substrate when the bonding temperature was below $140^{\circ}C$ so bonds were made at temperatures of $163^{\circ}C$, $178^{\circ}C$ and $199^{\circ}C$ for further testing. The bonding time and pressure were constant to 3 sec and 3.038 MPa. To test bond reliability, FPD assemblies were subjected to thermal shock storage tests ($-30^{\circ}C$, $1\;Hr\;{\leftrightarrow}80^{\circ}C$, 1 Hr, 10 Cycles) and func! tionality was verified by driver testing. It was found all of FPDs were functional after the thermal cycling. Additionally, Au bumps were bonded using ACF's with higher conductive particle densities at bonding temperatures above $163^{\circ}C$. From the experimental results, when the bonding temperature was increased from $163^{\circ}C$ to $199^{\circ}C$, the curing time could be reduced and more conductive particles were retained at the bonding interface between the Au bump and glass substrate.

• 마이크로전자및패키징학회지
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• 제13권4호
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• pp.77-84
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• 2006

도금전류밀도와 도금액 온도에 따른 비시안계 Au 범프의 표면 거칠기 및 웨이퍼 레벨에서 Au 범프의 높이 분포도를 분석하였다. $3mA/cm^{2}$와 $5mA/cm^{2}$에서 도금한 Au 범프는 $40^{\circ}C$와 $60^{\circ}C$의 도금액 온도에 무관하게 $80{\sim}100nm$의 낮은 표면 거칠기를 나타내었다. $8mA/cm^{2}$로 도금시 $40^{\circ}C$에서 도금한 Au 범프는 표면 거칠기가 800nm 정도로 크게 증가하였으나, $60^{\circ}C$에서 형성한 Au 범프는 $80{\sim}100nm$의 표면 거칠기를 나타내었다. 도금전류밀도가 $3mA/cm^{2}$에서 $8mA/cm^{2}$로 증가함에 따라 웨이퍼 레벨에서 Au 범프의 높이 편차가 증가하였으며, 도금액 온도가 $40^{\circ}C$보다 $60^{\circ}C$일 때 웨이퍼 레벨에서 더 균일한 범프 높이의 분포도를 얻을 수 있었다.

• Tribology and Lubricants
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• 제28권4호
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• pp.173-177
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• 2012

We used contact resonance force microscopy (CRFM) technique to determine the quantitative elastic properties of multiple materials integrated on the sub micrometer scale. The CRFM approach measures the frequencies of an AFM cantilever's first two flexural resonances while in contact with a material. The plain strain modulus of an unknown or test material can be obtained by comparing the resonant spectrum of the test material to that of a reference material. In this study we examined the following bumping materials for flip chip by using copper electrode as a reference material: NiP, Solder (Sn-Au-Cu alloy) and under filled epoxy. Data were analyzed by conventional beam dynamics and contact dynamics. The results showed a good agreement (~15% difference) with corresponding values determined by nanoindentaion. These results provide insight into the use of CRFM methods to attain reliable and accurate measurements of elastic properties of materials on the nanoscale.

• 한국재료학회지
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• 제5권6호
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• pp.673-681
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• 1995

아황산금나트륨염을 이용하여 형성된 약 20$\mu\textrm{m}$ 금도금층의 표면형상 및 우선적 결정 성장 방향에 대하여 전류밀도, 온도, 농도, pH, 교만속도, 금이온농도가 미치는 영향에 대하여 연구하였다. 표면형상은 cathode 근처의 금이온농도가 증가하는 조건[전류밀도(13.0mA/$\textrm{cm}^2$2$\longrightarrow$4.6mA/$\textrm{cm}^2$)], 온도 (3$0^{\circ}C$$\longrightarrow$6$0^{\circ}C$), pH(12.0$\longrightarrow$9.0), 교반효과(Orpm$\longrightarrow$3200rpm), 금이온농도(10g /1$\longrightarrow$l4g/1)으로 갈수록 porous한 조직에서 미세한 조직으로의 변화가 관찰되었다. X선분석에 의하면 금도금층의 결정성장의 주방향은 표면형상과 밀접한 관계를 나타내었으며 표면형상이 미세화되는 조건인 전류밀도(13.0$\longrightarrow$14.6mA/$\textrm{cm}^2$), pH(12.0$\longrightarrow$9.0)는 감소 할수록, 온도(3$0^{\circ}C$$\longrightarrow$6$0^{\circ}C$), 교반속도(0rPm$\longrightarrow$3200rpm), 금이온농도(10g/1$\longrightarrow$g/1)]는 증가 할수록 결정성장의 주회절피크는 (111)에서 (220)으로 그 성장면이 변하고 있음이 조사되었다.

• 한국표면공학회지
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• 제50권3호
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• pp.170-176
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• 2017

EPIG (Electroless Pd/immersion Au) process was studied to replace ENIG (electroless Ni/immersion Au) and ENEPIG (electroless Ni/electroless Pd/immersion Au) processes for bump surface treatment used in high reliable flip chip packages. The palladium and gold layers formed by EPIG process were uniform with thickness of 125 nm and 34.5 nm, respectively. EPAG (Electroless Pd/autocatalytic Au) also produced even layers of palladium and gold with the thickness of 115 nm and 100 nm. TEM results exhibited that the gold layer in EPIG surface had crystalline structure while the palladium layer was amorphous one. After annealing at 250 nm, XPS analysis indicated that the palladium layer with thickness more than 22~33 nm could act as a diffusion barrier of copper interconnects. As a result of comparing the chip shear strength obtained from ENIG and EPIG surfaces, it was confirmed that the bonding strength was similar each other as 12.337 kg and 12.330 kg, respectively.

• 한국재료학회지
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• 제6권7호
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• pp.700-708
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• 1996

Flip chip bonding에 무전해도금기술을 적용하여 solder bumper형성의 최적 조건을 규명하였다. 시편은 AI 패턴된 4 inch Si 웨이퍼를 사용하고, 활성화 처리시 zincate 용액을 사용하였으며, 무전해 도금은 Ni-P 도금액고 Au immersion 용액을 사용하였다. 활성화 물질의 AI 침식정도 및 Zn 석출 정도를 알아보기 위하여 EDS측정을 하였고, 각 공전에서의 표면형상을 알아보기 위해 SEM 분석을 하였다. 열처리 후 금도금층의 주 결정성장 방향은 XRD를 이용하여 측정하였다. 산처리에서 질산과 황산 중 질산에 의한 산화막제거 정도가 더 우수하게 나타났다. 활성화 처리시 zincate 용액을 희석시킬수록 입자 크기가 미세해 지고, 활성화 물질은 pH 13-13.5, 상온, 농도 15-25%의조건에서 크기가 작은 Zn 활성화 물질이 균일하게 분포하였다. Ni과 Auan전해도금 속도는 온도와 pH가 증가할수록 증가하였다. Ni 무전해 도금 조건은 pH 4.5, 온도 $90^{\circ}C$, 시간 20분이며, Au 무전해 도금조건은 pH7, 온도 $80^{\circ}C$, 시간 10분이었다. 상온에서 $400^{\circ}C$까지 30분동안 열처리 한 후 금도금막의 결정 방향은 pH 7, 온도 $80^{\circ}C$, 시간 10분이었다. 상온에서 $400^{\circ}C$까지 30분 동안 열처리 한 후 금도금막의 결정 방향은 pH 7에서 (111), pH 9에서는 (200)과 (111)이 주 peak로 나타났으며, 열처리에 의한 결정 방향의 변화는 없었다. 전체 공정에서 최종적인 표면 형상에 영향을 주는 단계는 활성화 처리로서 flip chip의 bonding layer형성에 가장 중요한 요소임을 알 수 있었다.보다 자생지(自生地)에서 높은 함량(含量)을 보였다. 5. 무기성분함양(無機成分含量)의 차이(差異)는 K의 경우(境遇) 자생지(自生地)에서 보다 재배지(栽培地)에서 평균적(平均的)으로 10배이상(倍以上) 정도(程度) 높은 함량(含量)의 차이(差異)를 보였으나 Mn, Zn, Na, Cu 등(等)은 일정(一定)한 경향(傾向)을 보이지 않는 것으로 나타났다. 6. 유리(遊離) 아미노산(酸)의 함량(含量)은 자생지(自生地은)보다 재배지(栽培地)에서 전반적(全般的)으로 높은 함량(含量)을 나타내었고, 특(特)히 Arginine은 다른 성분(成分)들과 비교(比較)해 볼 때 가장 높은 조성(組成)의 차이(差異)를 나타내었다. 7. 야생(野生)더덕과 재배(栽培)더덕의 정유성분수율(精油成分收率)은 자생지재배(自生地栽培)에서는 모두 0.004% 였고 재배지(栽培地)에서는 야생(野生)더덕이 0.005%였다. 8. 더덕의 재배장소(栽培場所)에 따른 향기성분(香氣成分)은 총(總) 21종(種)이었으며 自生地(自生地)에서 야생(野生)더덕은 16종(種), 재배(栽培)더덕은 18종(種)이었고, 재배지(栽培地)에서 야생(野生) 더덕은 14종(種), 재배(栽培)더덕은 20(種)이었다. 9. Trans-2-hexanol은 야생(野生)더덕의 자생지(自生地) 재배(栽培)에서 피이크 면적(面積) 당(當) 50.3%, 재배지(栽培地)에서 피이크 면적(面積) 당(當) 43.3%를 보였으며 amylalcohol, furfuryl acetate, 2-methoxy-4-vinyl phenol(MVP)는 재배(栽培)더덕에서만 확인(確認)되었다.는 KI, BMI와 유의적인 양의 상관관계를 보였고 (p<0.01), HCL-C은 비체중, BMI, LBM, TBM와 유의적인 음의 상관관계를 보였으며, (p<0.01), KI, SBP와도 음의 상관관계를 보였다. (p<0.05), LCL-C는 KI와 유의적이인 양의

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2003년도 춘계학술발표대회 개요집
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• pp.224-227
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• 2003

The longitudinal thermosonic bonding method is investigated in this work for its application to the soldering process for electronic packaging. The effect of the ultrasonic is analyzed through lumped modeling, and the material properties of a viscoelastic model are measured experimentally. The thermosonic bonding method is verified by inserting the Cu pin and Au bump into solder block. As the solder thickness decreases, temperature of the solder is calculated to increase rapidly because of larger strain. Localized heating due to ultrasonic vibration is observed to melt the solder near the pin, which is adequate to the high density electronic package and Pb-free solder having high melting temperature.