电子类专业英语电子教案第十一课

null11 PCB11 PCB学习重点： （1）掌握有关印刷电路板的基本单词、词组和缩略语的基本含义及用法 （2）培养阅读翻译有关印刷电路板的科技文献和产品说明 书 关于书的成语关于读书的排比句社区图书漂流公约怎么写关于读书的小报汉书pdf 的能力 （3）学习科技英语中的复合词与缩略词，掌握其构词和翻译方法null生词 accommodate[ ə'kɔmədeit ] v. 使适应；调节 automate [ 'ɔ:təmeit ] v. 自动化 vt. 使自动化 Passage A Introduction to PCB Manufacturenullbasis [ 'beisis ] n. 基础；根据 biochemical [ 'baio'kemikəl ] a. 生物化学的 bond [ bɔmd ] n.& v. 结合；粘合剂 catalysis [ kə'tælisis ]  n. 催化作用 compound [ 'kɔmpaund ] n. 混合物；化合物；复合物 chloride [ 'klɔ:raid ] n. 氯化物；漂白粉 clad [ klæd ] vt. 覆盖 n. & a. 包层（的） cure [ kjuə ] n. & v. 治疗；治愈；改正；固化 connectivity [ kənek'tiviti ] n. 连通性 concentration [ .kɔnsen‘treiʃən ] n. 浓度nullconstituent[ kən'stitjuənt ] n. 成份； 构成物 a. 构成的；组织的 degrade [ di'greid ]  v. 降低...的品格；退化；降解 destruction [ dis'trʌkʃən ] n. 破坏；毁灭 etch [ etʃ ] n. 腐蚀剂；v. 蚀刻；铭刻 metabolic [ .metə'bɔlik ] a. 新陈代谢的 milling [ 'miliŋ ] n. 磨；制粉；铣 oxidation [ ɔksi'deiʃən ] n. 氧化 prototype[ 'prəutətaip ] n. 原型；样品 registration [ .redʒis'treiʃən ] n. 重合；对齐 strain [ strein ] n. 紧张，拉紧 v. 劳累；拉紧 toxic [ 'tɔksik ] a. 有毒的 warp [ wɔ:p ] n. 弯；歪曲 v. 弄歪2. 课文翻译讲解2. 课文翻译讲解Printed circuit boards, PCBs, used to provide the mechanical basis on which the circuit can be built, are very widely used in the electronics industry as the basis for electronic circuits. Accordingly, virtually all circuits use printed circuit boards today. A PCB is shown in Figure 11-1 as an example. 翻译：印刷电路板（PCB），用来提供机械的基底，在它上面可以构建线路，PCB作 为电子线路的基底广泛应用于电子工业中。因此，实际上现今所有的电路都用印刷电 路板。作为一个例子，图11-1显示了一PCB板。null Although PCBs to form the basis of virtual all electronic circuits tend to be taken for granted today, the technology in this area of electronics is moving forward. Track sizes are decreasing, the numbers of layers in the boards is increasing to accommodate for the increased connectivity required, and the design rules are being improved to ensure that smaller SMT devices can be handled and the soldering processes used in production can be accommodated. 翻译：虽然今天PCB构成几乎所有电子电路的基底理所当然的，然而，在电子学 领域这一技术仍在不断发展。PCB印刷线的尺寸正在减小，板的层数正在增加以 适应所需连通性的提高， 设计 领导形象设计圆作业设计ao工艺污水处理厂设计附属工程施工组织设计清扫机器人结构设计 规则也正在改进，从而确保能操作较小的表面贴装 技术器件，并适应生产所用的焊接处理。null Printed circuit boards, PCBs, can be made from a variety of substances. The most widely used in a form of glass fiber based board known as FR4. This provides a reasonable degree of stability under temperature variation and is not breakdown badly, while not being excessively expensive. 翻译：印刷电路板（PCB）可以由多种物质制成。最常用的是某种形式的玻璃纤维 板，称为FR4。这种材料在温度变化时提供合理的稳定度，不容易损坏，而且也不 很昂贵。nullOther cheaper materials are available for the PCBs in low cost commercial products. For high performance radio frequency designs where the dielectric constant of the substrate is important, and low levels of loss are needed, then PTFE based printed circuit boards can be used, Fig. 11-1 a PCB although they are far more difficult to work with.翻译：在低廉的PCB商品中可用其它较便宜的材料。对于高性能的射频设计，其 基底的介电常数很重要，且需要有低的损耗，可以用基于PTFE（聚四氟乙烯）材 料的印刷电路板，但它们在加工时有一定的难度。null In order to make a PCB with tracks for the components, copper clad board is first obtained. This consists of the substrate material, typically FR4, with copper cladding normally on both sides. This copper cladding consists of a thin layer of copper sheet bonded to the board. This bonding is normally very good for FR4, but the very nature of PTFE makes this more difficult, and this adds difficulty to the processing of PTFE PCBs. 翻译：为了制作具有连接元件印刷线的PCB，首先要获得一块覆铜板。它由在板 的两面覆上铜的基底材料构成，这个基底材料通常是FR4。所覆的铜是一薄层粘 合在板上的铜层，对FR4板这种粘合是非常好的。但是，正是PTFE的特性使得 这种粘合更难，这也就增加了PTFE板制作的难度。null With the bare PCB chosen and available the next step is to create the required tracks on the board and remove the unwanted copper. The manufacture of the PCBs is normally achieved using a chemical etching process. The most common form of etch used with PCBs is ferric chloride. 翻译：选择好裸的、可用的PCB板之后，下一步是在板上创立所需的印刷线并且清 除不需要的铜。PCB的生产通常采用化学腐蚀处理的方式。最常用的腐蚀剂是铁氯 化物。null In order to gain the correct pattern of tracks, a photographic process is used. Typically the copper on the bare PCB is covered with a thin layer of photo-resist. It is then exposed to light through a photographic film or photo-mask detailing the tracks required. In this way the image of the tracks is passed onto the photo-resist. With this complete, the photo-resist is placed in a developer so that only those areas of the board where tracks are needed are covered in the resist. 翻译：为获得正确的印刷线图案，要用照相技术。通常裸的PCB上的铜层覆盖着一薄 层光阻材料，然后通过胶卷或光掩膜曝光，详细地显现出了所要的印刷线印迹。用这 种方法，印刷线图案就印制在光阻材料上。这些完成后，把光阻材料放在显影剂里， 这样，只有那些需要在板上敷设印刷线的区域能被光阻材料所覆盖。null The next stage in the process is to place the PCB into the ferric chloride to etch the areas where no track or no copper is required. Knowing the concentration of the ferric chloride and the thickness of the copper on the board, it is placed into etch required amount of time. If the PCB is placed in etch for too long, and then some definition is lost as the ferric chloride will tend to undercut the photo-resist. 翻译：制做过程的下一步是把PCB放在铁氯化剂中，把没有印刷线或不需要铜层的地 方腐蚀掉。知道了铁氯化剂的浓度和板上铜层的厚度，就可将PCB按所要求的时间放 到腐蚀剂中。如果PCB放到腐蚀剂中的时间太长，图案的一些轮廓清晰度会消失，因 为铁氧化剂将会切割光阻材料。null Although most PCBs are manufacturing using photographic processing, other methods are also available. One is to use a specialized highly accurate milling machine. The machine is then controlled to mill away the copper in those areas where the copper is not required. The control is obviously automated and driven from files generated by the PCB design software. This form of PCB manufacture is not suitable for large quantity but it is an ideal option in many instances where very small prototype quantities are needed. 翻译：虽然大部分PCB用照相技术生产，但也可用其它的方法。其中的一种就是 用专用的高精度铣床，用机器铣掉那些不需要铜的区域上的铜。机器的控制显而 易见是自动的，并且由PCB设计软件产生的文件来驱动。这种方式不适应于大批 量生产，而在大多只需要生产小批量样品时，它是一个理想的选择。null With the complexity of electronic circuits increasing, it is not always possible to provide all the connectivity that is required using just the two sides of the PCB. This occurs quite commonly when dense microprocessor and other similar boards are being designed. When this is the case multilayer boards are required.翻译：随着电子电路复杂性的增加，仅用双面的PCB不能满足所有连接的需求。 当设计密集性微处理器及其它相似的板时，尤其是这样。这时，就需要用多层 PCB了。 null The manufacture of multi-layer PCBs, although it uses the same processes as for single layer boards, requires a considerably greater degree of accuracy and manufacturing process control. Using much thinner individual boards makes the boards, one for each layer, and these are then bonded together to produce the overall PCB. As the number of layers increases, so the individual boards must become thinner to prevent the finished PCB from becoming too thick. Additionally the registration between the layers must be very accurate to ensure that any holes line up.翻译：虽然多层板的生产方法与单层板相同，但是要求有相当高的精度和生产过程控 制。板的每层分别用更薄的单独的板，然后各层板粘合成整块PCB板。当板的层数增 加时，每层板必须更薄，以免完整的PCB变得太厚了。另外，各层板之间的对齐必须 非常精确，以确保任何需要对齐的孔都能对齐。null To bond the different layers together the board is heated to cure the bonding material. This can lead to some problems of warp. Large multi-layer boards can have a distinct warp on them if they are not designed correctly. This can occur particularly if, for example one of the inner layers is a power plane or a ground plane. 翻译：为了将不同层粘合在一起，印制板被加热以固化粘合材料。这样可能导致出现 弯曲问题。若设计不当，大的多层板上会有不同的弯曲。例如，若其中一个内部层是 电源层或接地层，尤其会发生这种这情况。 nullThe manufacture of PCBs is an essential element of the electronics production and many new technologies have employed and this has enabled significant improvements to be made both in the reduction of sizes of components and tracks used, and in the reliability of the boards. PCBs are very stable compounds and do not degrade readily. 翻译：PCB的制造是电子学生产的一个重要要素，并使用了许多新技术，且新技术 的使用使得在缩小组件和印刷线的尺寸以及在板的可靠性两方面都得到了极大的改 进。 PCB是非常稳定的复合物而不会迅速地降解。 nullThey may be destroyed by chemical, thermal, and biochemical processes, though it is extremely difficult to achieve full destruction, and there is the risk of creating extremely toxic dibenzodioxins and dibenzofurans through partial oxidation. Because of the high thermodynamic stability of PCBs, all degradation mechanisms are difficult to sustain. Intentional degradation as a treatment of unwanted PCBs generally requires high heat or catalysis. Environmental and metabolic degradation generally proceeds quite slowly relative to most other compounds. 翻译：它们可被化学的、热的或生物化学的过程所破坏，但要达到完全的破坏是非 常困难的，且通过部分氧化有产生极毒的二苯并二氧化芑和二苯并氧杂茂的危险。 因为PCB具有高的热力学稳性，所有难以找到理想的降解机制都。有效处理废弃 PCB的降解方法一般要求高热或催化作用。对于大多数其它复合物进行有利于环境 或新陈代谢的降解处理过程也是相当慢。 3.疑难解析3.疑难解析1) Although PCBs form the basis of virtual all electronic circuits today, they tend to be taken for granted, and the technology in this area of electronics is moving forward. 虽然今天用PCB构成几乎所有电子电路的基底被认为是理所当然的，然而，在电子学领域这一技术仍在不断发展。 be taken sth. for granted 意为“ 认为…是理所当然的, 认为…是不成问题的”。null2) Track sizes are decreasing, the number of layers in the boards is increasing to accommodate for the increased connectivity required, and the design rules are being improved to ensure that smaller SMT devices can be handled and the soldering processes used in production can be accommodated. PCB印刷线的尺寸正在减小，板的层数正在增加以适应所需连通性的提高，设计规则也正在改进，从而确保能操作较小的表面贴装技术器件，并适应生产所用的焊接处理。 the number of …意为“…..的数量”，后接名词，其谓语动词用单数形式；a number of 意为“一些，若干”；any number of 意为“很多，好多”， 后面都接可数名词，谓语动词用复数形式。4 语法应用4 语法应用科技英语中的复合词与缩略词 1) 复合词：复合词可由两个或更多的单独词组成。由于作者可任意构词，给翻译往往带来一定的困难。但只要掌握其规律，就可克服这些困难。科技英语里最常见两种复合词：复合名词和复合形容词，有时也可见到复合动词。复合词的词性通常由第二个词确定，而重音通常在第一个词上。现将构成规律分别简述如下： 复合名词：在科技英语里最常见的复合名词形式有：名词+名词，如：photo-resist ，base-station ，theater-quality；null动名词+名词，如writing-room；形容词+名词，如：multi-layer，real-time ，high-voltage ；名词 +动名词，如：paper-making。 复合形容词：在科技英语里常见的复合形容词有：名词+形容词，如：light-sensitive、corrosion-resistant；名词+过去分词，如：integrator-based 、time-modulated、current-controlled；形容词+形容词，如：deep-green；形容词+ 现在分词，如：hard-working；形容词 +过去分词，如：well-known；副词 +过去分词, 如：thickly-insulated，等等。null复合动词：名词+动词，如: hand-select 、man-handle ；动词+动词，如blow-dry；形容词+动词，如：short-circuit；动词+副词，如：step-up。 2) 缩略词：科技英语中大量使用缩略词，它以其高效、醒目、易记等特点被越来越多地使用。缩略词是由词的音节，或多个词的第一个字母加以省略或简化而成，但它的词义不变。例如在本课中的ADC，DAC, CD, IDSN, DSL, VoIP等。现代缩略词趋向于任意构词，例如，某一篇论文的作者可以就仅在该文中使用的术语组成缩略词。 null另外要注意的是，缩略词与专业有关，同一缩略词在不同的专业中代表的原词是不一样的，其意义也不同。例如本课中的LP在电子学代表的原文为long playing，意为“密纹唱片”；在化学中代表的原文为laminated plastics, 意为“层压塑料”；在数学中代表的原文为liner programming, 意为“线性规划”；在宇航中代表的原文为liquid propellant, 意为“液体推进燃料”，等等。