Preparation of PVOH coatings with graphene nanoplatelets for electrostatic discharge protective packaging

This study investigated the use of graphene nanoplatelets (GNP) as a conductive filler for electrostatic discharge (ESD) protective packaging. Various weight concentrations of GNP were mixed and sonicated with polyvinyl alcohol (PVOH). The resulting polymer solution was applied as a coating to corrugated board in order to form an ESD packaging. Surface resistivity, mechanical strength and coating adhesion were then measured. The study found that the electrical percolation threshold of the PVOH/GNP coating is 9–13wt% GNP. GNP incorporated PVOH coatings with surface resistivity of 10³–10⁸ Ω/sq. generally meet all of ESD packaging requirements. The humidity strongly affects the surface resistivity of the coatings below the percolation threshold, but the change of the surface resistivity with humidity is less significant above the percolation threshold.     

蔬果类商品网上直销包装作业工序优化模型研究

针对蔬果类商品网上直销模式下,其标准销售单元包装作业问题规模大、商品品类多、订单个性化强、生产配送周期多等特点,基于批量流水作业生产、JIT准时制生产及周期调度的思想,研究该类商品标准销售单元包装作业的生产调度问题,建立蔬果类商品网上直销包装作业优化模型,并设计改进的“模拟增压——退火算法”对其进行求解,以便制定出合理的包装作业计划,有效衔接采摘和订单分拣作业以及后续装车作业,缩短包装时间,保证蔬菜的新鲜性。最后,通过应用实例验证模型和算法的有效性,结果表明,本文周期调度方法得到的调度方案比一般的非周期调度方法大大节约了包装作业成本,为蔬果类商品网上直销企业生成包装作业计划提供了理论指导。     

堆叠封装PoP返修工艺技术

返修是电子组装过程中不可避免的一个环节。Po P返修是一项技术性与技巧性都很强的操作,需要较高的操作技能水平和工艺控制手段。介绍了Po P器件的特点及其组装工艺技术,详细阐述了Po P器件的返修工艺技术。同时指出,返修是对PCB局部加热,往往会导致PCB上局部温度过高,因此多次高温带来金属氧化、金属间化合物的过度生长等问题也不容忽视。用科学的方法全面掌握工艺控制重点,了解返修设备与工艺材料特性,是返修成功的关键。     

Preparation and characterization of an asphalt-modifying agent with waste packaging polyethylene and organic montmorillonite

In this paper, waste packaging polyethylene (WPE)/organic montmorillonite (OMMT) nanocomposites were prepared and used as an asphalt-modifying agent. The structure and morphology of the nanocomposites and the effects of OMMT on the thermal properties of WPE were investigated. The influence of the microcosmic effects and physical properties of the composite agents on the base asphalt were also studied. The results show that the WPE/OMMT asphalt-modifying agents are exfoliated nanocomposites. When compared with WPE, the melting range of the composites decreases and the thermal stability is improved. In addition, the composite agents not only promote good dispersion of WPE in asphalt, but also improve the low temperature properties of WPE-modified asphalt without adversely affecting its excellent high temperature properties. Therefore, from an environmental and economic standpoint, it is a novel and significant attempt at dealing with waste plastics packaging.     

微波消解-石墨炉原子吸收光谱法测定纸质食品包装材料中的痕量镉

建立了微波消解–石墨炉原子吸收光谱法测定纸质食品包装材料中痕量镉的检验方法。样品经微波消解后,以硝酸镍为基体改进剂,试验确定了石墨炉原子吸收法测定镉的最佳仪器条件。镉的质量浓度在0～10μg/L与吸收峰面积呈良好的线性关系,线性相关系数r=0.9997,检出限为0.025μg/L。将该法用于纸质食品包装材料中痕量镉的测定,并进行加标回收试验,回收率为96.0%～105.5%,相对标准偏差不大于4.4%(n=10)。     

氢化物-原子荧光法测定食品容器及包装材料用聚酯树脂及其成型品中的微量锑

为建立简便、快速、高效测定食品包装材料中微量锑的方法,样品用4%乙酸处理后,利用氢化物-原子荧光法检测食品包装材料中的微量锑.结果表明,锑质量浓度在0～20 μg/L范围内呈现良好的线性,回归方程为y =87.284 C-17.440,相关系数r=0.999 9,检出限为0.028 4 μg/L,相对标准偏差RSD为0...     

高密度封装二极管激光器阵列

 理论模拟了自制的高效冷却器的散热能力,分析了单元封装结构所需材料的导热特性,获得了高功率二极管激光器在高功率密度、高占空比条件下运行的可行性。改进了高密度封装的关键工艺,热沉金属化层达到了3~5 mm,焊料厚度为4~7 mm,封装间距0.6 mm,采用峰值功率1 kW的背冷式叠阵二极管激光器。实验测试结果表明:封装的二极管激光器叠阵单元的整体封装热阻为0.115 ℃/W,有良好的散热能力;该叠阵模块在电流为100 A、占空比15%时,输出峰值功率为986 W,峰值功率密度达到1.5 kW/cm2,平均每个板条的斜效率为1.25 W/A,激光器阈值电流为20 A左右。     

Effect of Processing Treatment and Modified Atmosphere Packing on Carrot’s Microbial Community Structure by Illumina MiSeq Sequencing

The aim of this study was to analyze the microbiome of carrot (Daucus carota subsp. sativus) subjected to minimal pre-treatment (rinsing in organic acid solution) and packaging in a high-oxygen modified atmosphere, and then stored for 17 days under refrigeration conditions (4 °C). The highest levels of bacteria in the carrot microbiome were characterized, at almost 78%, by bacteria belonging to the Enterobacteriaceae and Pseudomonadaceae families. Rinsing in a solution of ascorbic and citric acids resulted in the improvement of microbiological quality in the first day of storage. However, the use of a high-oxygen modified atmosphere extended the shelf life of the minimally processed product. Compared to carrots stored in air, those stored in high oxygen concentration were characterized by a greater ratio of bacteria belonging to the Serratia and Enterobacter genera, and a lower ratio belonging to the Pseudomonas and Pantoea genera. Moreover, the β-biodiversity analysis confirmed that the oxygen concentration was the main factor influencing the differentiation of the metabiomes of the stored carrots. The bacterial strains isolated from carrots identified by molecular methods were mostly pathogenic or potentially pathogenic microorganisms. Neither the minimal pre-treatment nor packaging in high-oxygen atmosphere was able to eliminate the threat of pathogenic bacteria emerging in the product.     

LCCC封装器件热疲劳失效分析及结构优化研究

针对LCCC封装器件在温度循环载荷下焊点开裂的问题,首先分析其失效现象和机理,并建立有限元模型,进行失效应力仿真模拟。为降低焊点由封装材料CTE不匹配引起的热应力,提出了两种印制板应力释放方案,并分析研究单孔方案中不同孔径和阵列孔方案中不同孔数量对热疲劳寿命的影响。之后,为降低对PCB布局密度的影响,提出一种新型的叠层焊柱应力缓冲方案,进行了不同叠层板厚度和焊柱间距的敏感度分析。结果表明,更大的开孔面积、更小的叠层板厚度、更密的焊柱可有效降低焊点应力,提高焊点热疲劳寿命,使得LCCC封装器件焊点热疲劳可靠性得到有效提高。     

绿色电子制造及绿色电子封装材料

阐述了绿色电子制造(包括电子封装)概念起源、定义以及基本内涵和范畴,并从电子封装用互连材料、被连接材料和封装后清洗过程这三个方面全面阐述了绿色电子封装的主要内容,重点评述了目前绿色电子封装材料(包括无铅钎料、钎剂、焊膏和导电胶等)的研究现状和面临的问题.最后,展望了绿色电子制造及绿色电子封装材料的未来发展趋势.