1D介质型EBG噪声隔离性能的有限元建模分析

提出了一种分析多层印刷电路板电源分配网络（power distribution network, PDN）中一维（1D）介质型电磁带隙（electromagnetic band-gap, EBG）结构噪声隔离性能的1D有限元数值计算方法. 将1D介质型EBG的3D结构简化为1D有限元模型,通过直接求解波动方程获得传输系数T、反射系数R以及散射参数S. 利用R-T曲线可直观地判定频率禁带,而采用分贝表示的S₂₁参数则更方便评价噪声隔离度. 根据介质型EBG的周期数、介电常数和周期长度等参数对噪声隔离性能影响的仿真结果,针对少周期、不完全禁带EBG结构提出了先采用多周期EBG结构预测禁带,再通过调整介电常数和周期长度扩展禁带和增强噪声隔离度的两阶段设计方法. 采用3D全波电磁仿真验证了1D有限元算法的合理性.     

微波印制电路板制造工艺及其电阻集成

介绍了微波印制电路板制造工艺中的钻孔、孔金属化和图形制作等主要步骤以及电阻集成的方法。通过在微波印制电路板基材表面涂覆低介电常数的材料,改变了基材表面形貌和特性,采用薄膜工艺在微波印制电路板上集成了30～50Ω/的NiCr电阻。最后简要介绍了微波多层印制电路新技术。     

电子线路板热可靠性分析方法的研究

该文研究用ANSYS软件对电子线路板做热可靠性分析时的建模问题,通过仿真分析,得到如下两点推论：(1)铜箔分布的不均匀性对PCB传热有重要的引导作用,因此在建模时应尽量予以考虑;(2)内部到外部热阻小的发热元件可以当作简单方块来处理,这样就使整板的建模大大简化。根据以上推论对一种新型星载电子线路板进行了ANSYS建模和计算,并把计算的结果与实验测试数据进行比较分析,验证了这种简化建模方法具有足够的准确性,使用方便,可以应用于星载及真空等环境中各种电子线路板的热可靠性分析研究。     

利用硝酸型退锡废液回收锡单质的研究

研究一种清洁、低能耗、无副产物排放的从印制电路板硝酸型退锡废液中回收锡单质的方法。通过用絮凝剂、过滤方法得到锡酸沉淀;在高温条件下锡泥与浓盐酸反应生成锡离子,用还原剂将其中的锡离子还原成单质锡。最佳的反应条件为:100 ml退锡废液的絮凝剂及用量是5%聚丙烯酰胺14 ml;10 g锡酸的最佳浓盐酸用量40 ml,油浴温度140℃;最佳还原剂硼氢化钾的浓度1.2 mol/L,反应时间30 min。通过XRD表征,证实所制备的为锡单质。     

PCB企业如何筹建CNAS认可实验室

通过解读CNAS—CL01《检测和校准实验室能力认可准则》,从体系文件、人员配置、检测工作管理、设备管理、设施和环境条件控制五个要素为PcB企业筹建CNAS认可实验室提出一些建议。     

PCB工厂设备保养的问题及其对策

界定了PCB工厂设备使用部门和管理部门的保养责任,指出了这两个部门在保养方面普遍存在的问题。针对这些问题,作者结合实际案例分析了产生的原因,并提出了解决的对策。     

工作研究在PCB成型效率提升中的应用

改善生产要素组织,提高生产率是企业生产管理的永恒课题。针对我公司成型工序中存在的生产率低、工序步骤安排不合理等问题,应用工作研究的程序分析技术,首先阐述了成型工序的现状,然后用流程程序分析法优化工艺流程。通过改进,缩短了生产周期,提高了生产效率,从而使产能提高了5％。     

高速板材阶梯槽图形板制作研究

针对采用松下RX板材设计的高速板材阶梯槽图形板的制作进行研究。此板设计有槽底通孔、背钻孔、NPTH孔、整板的PTH阶梯孔、POFV孔。样板层数高,制作工艺复杂,难度大,对准度、阻抗以及可靠性要求高。     

Degradation of PCB by Bacteria Isolated from Long-Time Contaminated Soil

Abstract

Four bacterial isolates belonging to the genera Pseudomonas and Alcaligenes were obtained by the enrichment method, using biphenyl as the sole carbon source, from the soil, which underwent long-time contamination with technical mixtures of PCB. Kinetics of PCB degradation by individual isolates was measured using n-hexane extraction of the cultivation media in proper time intervals and analysed by congener specific gas chromatography with electron capture detection. All isolates exhibit interesting biodegradative potential. Specific degradation of individual congeners with respect to the number and position of chlorine substituents is discussed. The influence of glucose, biphenyl and 3-chlorobenzoic acid on the PCB degradation has been assessed.     

Compound-specific stable isotope analysis of organic contaminants in natural environments: a critical review of the state of the art,prospects, and future challenges

Compound-specific stable isotope analysis (CSIA) using gas chromatography-isotope ratio mass spectrometry (GC/IRMS) has developed into a mature analytical method in many application areas over the last decade. This is in particular true for carbon isotope analysis, whereas measurements of the other elements amenable to CSIA (hydrogen, nitrogen, oxygen) are much less routine. In environmental sciences, successful applications to date include (i) the allocation of contaminant sources on a local, regional, and global scale, (ii) the identification and quantification of (bio)transformation reactions on scales ranging from batch experiments to contaminated field sites, and (iii) the characterization of elementary reaction mechanisms that govern product formation. These three application areas are discussed in detail. The investigated spectrum of compounds comprises mainly n-alkanes, monoaromatics such as benzene and toluene, methyl tert-butyl ether (MTBE), polycyclic aromatic hydrocarbons (PAHs), and chlorinated hydrocarbons such as tetrachloromethane, trichloroethylene, and polychlorinated biphenyls (PCBs). Future research directions are primarily set by the state of the art in analytical instrumentation and method development. Approaches to utilize HPLC separation in CSIA, the enhancement of sensitivity of CSIA to allow field investigations in the µg L^–1 range, and the development of methods for CSIA of other elements are reviewed. Furthermore, an alternative scheme to evaluate isotope data is outlined that would enable estimates of position-specific kinetic isotope effects and, thus, allow one to extract mechanistic chemical and biochemical information.Abbreviations BTEX benzene, toluene, ethylbenzene, xylenes - MTBE methyl tert-butyl ether - PAHs polycyclic aromatic hydrocarbons - VOCs volatile compounds - PCBs polychlorinated biphenyls - CSIA compound-specific (stable) isotope (ratio) analysis - GC-IRMS, GC/IRMS or GCIRMS gas chromatography-isotope ratio mass spectrometry - GC-C-IRMS, GC/C/IRMS or GCC-IRMS gas chromatography-combustion-isotope ratio mass spectrometry - irmGC/MS isotope ratio monitoring gas chromatograph-mass spectrometry - GC/P/IRMS gas chromatography-pyrolysis-isotope ratio mass spectrometry (used for D/H) - KIE kinetic isotope effect - PSIA position-specific isotope analysis (for intramolecular isotope distribution) - SNIF-NMR site-specific natural isotopic fractionation by nuclear magnetic resonance spectroscopy