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291.
激光键合技术以其局部非接触加热、灵活性强和可控性能好的优点在电子封装、光电子封装以及MEMS封装中得到了应用。以几种激光键合技术的研究和应用为实例,分析和探讨了激光键合技术中的关键问题及其发展趋势。 相似文献
292.
建立了顶空/气相色谱-质谱联用(HS/GC-MS)测定食品接触材料中5-亚乙基-2-降冰片烯(ENB)迁移量的方法,对前处理方法(溶剂提取-直接进样和气液平衡-顶空进样)、顶空平衡温度、顶空平衡时间进行了优化。以水、4%(体积分数)乙酸、50%(体积分数)乙醇和橄榄油作为食品模拟物,样品经食品模拟物浸泡,于顶空气液平衡后进样,经DB-5 MS色谱柱(30 m×0. 25 mm×0. 25μm)分离后,采用选择离子模式进行检测,外标法定量。在优化实验条件下,ENB在0. 1~10 mg/L范围内呈良好的线性关系,相关系数(r)大于0. 999,在0. 1、1. 0、10 mg/L 3个加标水平下,方法的回收率为92. 0%~108%,相对标准偏差(RSD,n=5)为0. 9%~4. 0%,检出限(LOD)为0. 01 mg/kg,定量下限(LOQ)为0. 03 mg/kg。该方法准确、可靠、灵敏度高,适用于食品接触材料中ENB迁移量的测定。 相似文献
293.
A sensor with potential for the development of a “chemical barcode” for real-time monitoring of fish freshness is described. This on-package sensor contains a pH sensitive dye, bromocresol green, that responds through visible colour change to basic volatile spoilage compounds, such as trimethylamine (TMA), ammonia (NH3) and dimethylamine (DMA) collectively known as Total Volatile Basic Nitrogen (TVB-N). The sensor characteristics were studied as well as its response with standard ammonia gas. Trials on cod and under-utilised species have verified that the sensor response correlates with bacterial growth patterns in fish samples thus enabling the “real-time” monitoring of spoilage in various fish species. The sensor response can be interrogated with a simple, inexpensive reflectance colorimeter that we have developed based on two light emitting diodes (LEDs) and a photodetector. 相似文献
294.
食品包装材料上油墨中残留烷基苯成分分析及其迁移性的GC-MS研究 总被引:6,自引:0,他引:6
建立了一种食品包装材料上多色油墨中残留烷基苯成分的提取和气相色谱-质谱联用(GC-MS)分析方法. 采用选择离子检测(SIM)模式, 以内标定量法对某些食品包装材料上多色油墨中烷基苯残留量进行了准确定量分析. 对油墨中残留烷基苯向食品中迁移的初步研究结果表明, 包装材料上油墨中的苯及苯系物等有害物质可能透过薄膜进入食品而造成污染. 相似文献
295.
Yun-Hwan Jo Joo Won Lee Sun-Kyoung Seo Hyuck Mo Lee Hun Han Dong Chun Lee 《Journal of Electronic Materials》2008,37(1):110-117
A combination solder of Sn-3.0Ag-0.5Cu (numbers are all in weight percent unless specified otherwise) wrapped by Sn-57Bi-1Ag
was tested for application to three-dimensional (3-D) multistack packaging. The experimental variables controlled were the
reflow peak temperatures (170, 185, 200, and 230°C), the reflow cycles (up to four times), and the mask which controls the
amount of Sn-57Bi-1Ag solder paste (two sizes). We demonstrate and evaluate the combination solder structure, focusing on
microstructural changes and the shear strength. The degree of mixing in the combination solder, which is enhanced by an increase
in the reflow peak temperature, is independent of the number of reflow cycles. The ball shear strength and the lab shear strength
both increased with increases in the reflow peak temperatures. This behavior is explained by the amount of the brittle Bi
phase that constitutes the eutectic Sn-Bi phase. 相似文献
296.
S. C. Wang S. Chi K. C. Hsieh Y. D. Yang W. H. Cheng 《Journal of Electronic Materials》1997,26(8):L21-L23
Evidence of the Au segregation within the crack region in laser welded Au-coated Invar material for semiconductor laser packaging
is investigated. Results obtained from the metallography, scanning electron microscope (SEM) mapping, energy dispersive spectrometer
(EDS) line profile, and Auger electron spectroscopy find that the cracks in the welded joints occur around the Au rich boundaries.
The SEM Au mapping and EDS line profiles show that Au accumulates at the crack region. This direct observation indicates that
one of the primary causes of cracks in laser welded Au-coated materials is due to the segregation of Au in the final stage
of solidification. Detailed knowledge of the defect formation mechanisms in laser welded Au-coated materials is important
for the practical design and fabrication of reliable optoelectronic packaging. 相似文献
297.
寇亚男 《电子产品可靠性与环境试验》2003,(1):19-21
从器件的芯片结构及封焊工艺入手,分析了封焊工艺影响成品率的各种原因,并采取相应的改进措施,提高了器件的成品率。 相似文献
298.
Electroplated-Ni (EP-Ni) has been adopted gradually as an underbump metallization layer due to its comparatively lower resistivity
and higher deposition rate. In this study, the metallurgical reaction between eutectic Sn-Pb solder and EP-Ni as well as electroless-Ni
(EL-Ni) was investigated at 200°C, 210°C, 220°C, and 240°C. It is found that the growth rate of Ni3Sn4 intermetallic compound (IMC) on EP-Ni was slower than that on EL-Ni. The consumption rate is measured to be 0.97 × 10−3 μm/s and 1.48 × 10−3 μm/s for EP-Ni and EL-Ni, respectively. The activation energy is determined to be 51 kJ/mol and 48 kJ/mol for EP-Ni and EL-Ni,
respectively. The dense structure of EP-Ni may be responsible for the lower IMC formation rate. 相似文献
299.
Maria Alfredsson Furio Corà David P. Dobson John P. Brodholt G. David Price 《Surface science》2007,601(21):4793-4800
Doping is a common way to activate the behavior of ceramics. Its effect is not limited to the bulk: segregation of dopants to the surfaces also yields a way to modify, and ultimately control the crystal morphology. We propose a model that allows us to calculate the surface energy beyond the Langmuir isotherm for doped and defective surfaces from atomic-level simulations. The model also allows us to account for different compositions between the bulk and surface. Computational materials design can thus be applied to optimize simultaneously the crystal behavior at the atomic (surface structure and composition) and mesoscopic (crystal size and shape) length scales. We exemplify the model with orthorhombic CaTiO3 perovskite doped with Mg2+, Fe2+, Ni2+, Sr2+, Ba2+ and Cd2+ ions, by predicting the effect that different dopants and dopant concentrations have on the crystal morphology. We find that a higher proportion of reactive {0 2 1} and {1 1 1} surfaces are exposed with the presence of divalent Mg2+, Fe2+ and Ni2+ ions than in the undoped material and in perovskite doped with Ba2+ and Sr2+. Cd2+ has only minor effects on crystal morphologies. These findings have important implications for predicting the reactivity of crystals doped with different ions and we show how this can be related to a simple parameter such as the ionic radius. We have tested our newly derived model by comparison with laboratory flux grown single crystals of CaTiO3, (Ni, Ca)TiO3 and (Ba, Ca)TiO3 and find excellent agreement between theory and experiment. 相似文献
300.