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RISS 인기검색어
- 검색키워드
- 저자 : Anmin Hu (검색결과 6 건)
- 무료
- 기관 내 무료
- 유료
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Mitigation and Mechanism of Tin Whisker on Micro-bumps by Hard and Soft Underfills
Zhenzhen Shan,Ke Lin,Anmin Hu,Ming Li 대한금속·재료학회 2022 ELECTRONIC MATERIALS LETTERS Vol.18 No.6
It is the first time that the mitigation and mechanism of tin whisker on micro-bumps by different types of underfills are investigated under high temperature and humidity (55 ℃/88% RH) storage. Hard epoxy, soft silicone and polyurethane are selected as underfills to spin-coat the 10 μm-diameter and 20 μm-pitch Cu/Ni/SnAg micro-bumps. After six-month storage, underfills exhibite a good mitigation effect despite the surface decomposition, delamination, cracks and voids in varying degrees. Compared with the micro-bumps without underfill, the probability of whisker or hillock and oxidation or corrosion in micro-bumps is reduced by up to 66% and 96%, respectively. Based on the statistics and characterization results, the mitigation mechanism of tin whisker by underfills is proposed. The diameter and critical length of tin whisker are discussed as well to estimate its buckle or penetrate growth. Besides, several underfills failures are summarized. The findings are of great significance to the study of tin whisker mitigation on micro-bumps and provide insights into the reliability of advanced packaging.
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Jiunan Xie,Hua Hu,Peixin Chen,Han Lei,Anmin Hu,Yunwen Wu,Ming Li 대한금속·재료학회 2024 ELECTRONIC MATERIALS LETTERS Vol.20 No.3
A low-temperature solid-state bonding technology using palladium-coated Co micro-nano cones array (MCA) and Sn-3.0Ag-0.5Cu (wt%) solder was investigated. The Pd modifi cation layer on the surface of Co MCA reduced the growth of oxide fi lm. Low-temperature solid-state bonding was achieved using Co/Pd MCA under the bonding condition of 750 gf, 175 °C and150 s with the shear strength of 49.55 MPa, and there was no void found along the bonding interface. Microscopic observationrevealed that Co/Pd MCA was fully embedded in the soft solder. The average shear strength of the bonding joint wasmeasured and demonstrate that Co/Pd MCA has higher reliability than Co MCA. This work highlights the advantages ofbonding based on Co/Pd MCA, which has great potential for extensive practical applications.
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Sub-surface Damage of Ultra-Thin Monocrystalline Silicon Wafer Induced by Dry Polishing
Xundi Zhang,Chenlin Yang,Yumei Zhang,Anmin Hu,Ming Li,Liming Gao,Huiqin Ling,Tao Hang 대한금속·재료학회 2020 ELECTRONIC MATERIALS LETTERS Vol.16 No.4
Ultra-thin wafer fabrication has become a hot spot in recent years with the growing demand for small size and high performance electronic devices. However, far less research focused on the damage behavior in ultra-thin wafer. In this work, 300 mm diameter silicon wafer was thinned to 6 µm thick by grinding plus ultra-precision dry polishing. The damage behavior before and after the dry polishing was discussed. Mechanical and surface analysis showed that the dry polishing process can help improve the strength and surface uniformity of ultra-thin wafer by removing high pressure phase and micro cracks. Series of nano beam diffraction patterns revealed the stress induced by the thinning process only existed in surface. High resolution transmission electron microscopy images analyzed by geometric phase approach indicated that surface dislocations can move across the wafer and reached bottom device layers during the dry polishing, increasing the risk of electrical deterioration. The findings are of great significance to the study on process optimization of ultra-thin wafer and provide insights into the reliability of advanced electronic packaging.
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Effects of Sn Layer Orientation on the Evolution of Cu/Sn Interfaces
Menglong Sun,Zhangjian Zhao,Fengtian Hu,Anmin Hu,Ming Li,Huiqin Ling,Tao Hang 대한금속·재료학회 2018 ELECTRONIC MATERIALS LETTERS Vol.14 No.4
The effects of Sn layer orientation on the evolution of Cu/Sn joint interfaces were investigated. Three Sn layers possessing(112), (321) and (420) orientations were electroplated on polycrystalline Cu substrates respectively. The orientations of Snlayer preserved during reflowing at 250 °C for 10 s. After aging at 150 °C for different time, the interfacial microstructureswere observed from the cross-section and top-view. The alignment between the c-axis of Sn and Cu diffusion direction significantlysped up the Cu diffusion, leading to the thickest intermetallic compound layer formed in (112) joint. Two types ofvoids, namely, intracrystalline voids and grain islanding caused intercrystalline voids generated at Cu/Cu3Sn interfaces dueto the different interdiffusion coefficients of Cu and Sn (112) oriented Sn/Cu joint produced many more voids than (321)joint, and no voids were detected in (420) joint. Therefore, to enhance the reliability of solder joints, using (420) orientedSn as solder layer could be an efficient way.
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Formation Mechanism of Novel Sidewall Intermetallic Compounds in Micron Level Sn/Ni/Cu Bumps
Siru Ren,Menglong Sun,Zebin Jin,Yukun Guo,Huiqin Ling,Anmin Hu,Ming Li 대한금속·재료학회 2019 ELECTRONIC MATERIALS LETTERS Vol.15 No.5
A new kind of intermetallic compounds (IMC) were found around copper pillar in micron level bumps. To investigate theformation mechanism, three different sized Sn/Ni/Cu bumps (10 μm, 20 μm, 50 μm) were electroplated then reflowed at230 °C for 100 s. After reflow process, a thin layer of IMC was formed around copper pillar, which is attributed to surfacewetting behavior. After aging at 170 °C and 200 °C for different times, the growth mechanism of sidewall IMC was observedby scanning electron microscopy combined with electron backscatter diffraction (EBSD) technology. Surface diffusion wasconsidered to be the main driving force for sidewall IMC growth for the activation energy of them was found to be muchsmaller than that in previous studies. The EBSD results showed a preferred orientation of sidewall Cu3Sngrains <100> beingperpendicular to copper periphery, which indicated direction of Cu atoms flux during Cu3Sngrowth. Formation mechanismof this novel sidewall IMC was proposed based on surface wetting and surface diffusion. The findings contribute to the failuremechanism study in small size bumps and provide insights into the reliability of 3D electronic packaging.
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Yaqian Sun,Jing Wang,Xundi Zhang,Chenlin Yang,Anmin Hu,Tao Hang,Yunwen Wu,Huiqin Ling,Ming Li 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.6
At present, thermal compression bonding based on Cu and lead-free Sn based solder is often limited by high bonding temperature,which is higher than the melting point of solder (218 ℃). In this paper, we reported a low-temperature solid stateinsertion bonding method based on electroless Cu-Co-P micro-cones array. By adjusting the mass ratio of CuSO 4 ·5H 2 O andCoSO 4 ·7H 2 O, a series of Cu-Co-P micro-cones with diff erent morphologies were prepared. The Cu-Co-P micro-cones withhigher proportion of copper were sharper and denser and (111) orientation was also more. It was found that reducing theheight and density of micro-cones was conducive to achieve seamless bonding at lower temperature and force such as 170℃ and 750 gf. By optimizing the morphology of micro-cones, such as height, bottom diameter, vertex angle and density, theseamless and reliable bonding with high shear strength (39.9 MPa) could be achieved at 170 ℃ bonding temperature and1000 gf bonding force. The transmission electron microscopy results showed that intermetallic compounds including Cu 6 Sn 5and Cu 3 Sn existed at bonding interface, which indicated that signifi cant atomic diff usion had occurred between Cu-Co-Pmicro-cones and Sn based solder. Probable mechanisms for low-temperature insertion bonding were discussed.
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