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排序方式: 共有141条查询结果,搜索用时 15 毫秒
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Xingsheng Liu Shuangyan Xu Guo-Quan Lu David A. Dillard 《Microelectronics Reliability》2002,42(12):1142-1891
Solder joint fatigue failure is a serious reliability concern in area array technologies, such as flip chip and ball grid array packages of integrated-circuit chips. The selection of different substrate materials could affect solder joint thermal fatigue lifetime significantly. The reliability of solder joint in flip chip assembly for both rigid and compliant substrates was evaluated by accelerated temperature cycling test. Experimental results strongly showed that the thermal fatigue lifetime of solder joints in flip chip on flex assembly was much improved over that in flip chip on rigid substrate assembly. Debonding area of solder joints in flip chip on rigid board and flip chip on flex assemblies were investigated, and it was found that flex substrate could slow down solder joint crack propagation rate. The mechanism of substrate flexibility on improving solder joint thermal fatigue was investigated by thermal mechanical analysis (TMA) technique. TMA results showed that flex substrate buckles or bends during temperature cycling and this phenomenon was discussed from the point of view of mechanics of the flip chip assembly during temperature cycling process. It was indicated that the thermal strain and stress in solder joints could be reduced by flex buckling or bending and flex substrates could dissipate energy that otherwise would be absorbed by solder joints. It was concluded that substrate flexibility has a great effect on solder joint reliability and the reliability improvement was attributed to flex buckling or bending during temperature cycling. 相似文献
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Shuangyan Huan Qi Shen Guang ming Zeng Guo li Shen Ru qin Yu 《Electrochimica acta》2004,49(25):4273-4280
Specific selectivity toward different heavy metal ions could be introduced into self-assembled monolayers (SAMs) by ion imprinting. In the mixed solution, good response toward mercury ions could be obtained on mercury ions imprinted SAMs, the copper ions imprinted SAMs presented good selectivity toward copper ions, while on lead ions imprinted SAMs, significantly higher insertion of lead ions than mercury and copper ions were observed. Linear calibration plots were obtained for each heavy metal ion and the regression equations were: [Hg(II)]/(10−6 M), [Cu(II)]/(10−6 M) and [Pb(II)]/(10−6 M) for mercury, copper and lead ions, respectively. The detection limits were determined to be: 1.46×10−8 M for Hg(II), 3.73×10−8 M for Cu(II) and 4.34×10−8 M Pb(II). The decreases in current response for mercury, copper and lead ions in the presence of 100-fold interferential ions were: 3.37%, 9.16% and 7.60%, respectively. Acceptable recoveries were obtained in mixed solutions at both high and low concentrations. 相似文献
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在乐昌峡水利枢纽工程混凝土骨料料源选择阶段,初步选定的Ⅲ20料场灰岩为可能具有潜在危害性的碱-硅酸反应的可疑骨料。通过抑制碱活性反应试验研究表明,采取使用低碱水泥或在高碱水泥中掺粉煤灰的措施,对骨料的碱-硅酸活性反应均具有明显的抑制效果。本研究成果可为其他类似工程提供参考。 相似文献
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Rapid Detection of the Biomarkers for Carcinoid Tumors by a Water Stable Luminescent Lanthanide Metal–Organic Framework Sensor 下载免费PDF全文
Shuangyan Wu Yanna Lin Jingwei Liu Wei Shi Guangming Yang Peng Cheng 《Advanced functional materials》2018,28(17)
Serotonin (5‐hydroxytryptamine, HT), a neurotransmitter, and its main metabolite 5‐hydroxyindole‐3‐acetic acid (HIAA) are biomarkers for carcinoid tumors. They can be quantitatively detected by a new luminescent sensor based on a water stable lanthanide metal–organic framework (Ln‐MOF). This Ln‐MOF features a (3,4)‐connected topology containing 1D channels occupied by lattice water molecules. Luminescent studies reveal that high luminescence quenching efficiency occurs upon the addition of HT and HIAA. The Ln‐MOF also displays excellent sensitivity with fast response within 1 min, good reusability, and detection limits as low as 0.66 and 0.54 × 10?6m for HT and HIAA, respectively. In addition, the sensing function exhibits excellent selectivity even in the presence of other neurotransmitters and the main coexisting species in blood plasma and urine. 相似文献
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本文就利用诸如蛋白石这样的疏松多孔矿料同灰土构成的混合料,在路面结构中表现出的独特有效的抗冻作用机理作了深入分析,并结合足尺试验数据加以验证。阐述了所谓多孔板体结构的概念、机制和材料组成要求。 相似文献
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为具体分析放电过程中电场强度、电子密度、平均电子能量及鞘层的变化规律,通过简化化学反应动力学模型以及采用全时域漂移-扩散模型方程,对N2-O2混合气体的二维平行电极纳秒脉冲介质阻挡等离子体放电的发展演化过程进行数值模拟。计算结果发现:放电从电极处开始发展形成约化场强约为5×10-19 V?m2的强电场,高电压电极附近形成0.2 mm的鞘层区域,鞘层边缘存在数密度为1.6×1019 m-3的薄电子层,且其边缘分层结构与低气压辉光放电鞘层分层结构一致;电子沉积在介质表面,等离子体从强电场中获得的能量使得其在脉冲结束后的余辉过程中继续维持,进而有效地将能量耦合给等离子体。数值模拟结果表明,提出的简化化学反应动力学模型能够有效地模拟复杂的介质阻挡纳秒脉冲放电的物理过程及其各个物理参数的变化规律。 相似文献