電子類專業(yè)英語電子教案第十一課

1、學習重點：（1）掌握有關印刷電路板的基本單詞、詞組和縮略語的基本含義及用法 （2）培養(yǎng)閱讀翻譯有關印刷電路板的科技文獻和產品說明書的能力 （3）學習科技英語中的復合詞與縮略詞，掌握其構詞和翻譯方法 basis beisis n. 基礎；根據(jù)biochemical baiokemikl a. 生物化學的bond bmd n.& v. 結合；粘合劑catalysis ktlisis n. 催化作用compound kmpaund n. 混合物；化合物；復合物chloride kl:raid n. 氯化物；漂白粉clad kld vt. 覆蓋 n. & a. 包層（的）cure kj

2、u n. & v. 治療；治愈；改正；固化connectivity knektiviti n. 連通性concentration .knsentrein n. 濃度constituent knstitjunt n. 成份； 構成物 a. 構成的；組織的degrade digreid v. 降低.的品格；退化；降解destruction distrkn n. 破壞；毀滅etch et n. 腐蝕劑；v. 蝕刻；銘刻metabolic .metblik a. 新陳代謝的milling mili n. 磨；制粉；銑oxidation ksidein n. 氧化prototype prutta

3、ip n. 原型；樣品registration .redistrein n. 重合；對齊strain strein n. 緊張，拉緊 v. 勞累；拉緊toxic tksik a. 有毒的warp w:p n. 彎；歪曲 v. 弄歪2. 課文翻譯講解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 electron

4、ic circuits. accordingly, virtually all circuits use printed circuit boards today. a pcb is shown in figure 11-1 as an example. 翻譯：印刷電路板（pcb），用來提供機械的基底，在它上面可以構建線路，pcb作為電子線路的基底廣泛應用于電子工業(yè)中。因此，實際上現(xiàn)今所有的電路都用印刷電路板。作為一個例子，圖11-1顯示了一pcb板。 although pcbs to form the basis of virtual all electronic circuits tend

5、 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 devic

6、es can be handled and the soldering processes used in production can be accommodated. 翻譯：雖然今天pcb構成幾乎所有電子電路的基底理所當然的，然而，在電子學領域這一技術仍在不斷發(fā)展。pcb印刷線的尺寸正在減小，板的層數(shù)正在增加以適應所需連通性的提高，設計規(guī)則也正在改進，從而確保能操作較小的表面貼裝技術器件，并適應生產所用的焊接處理。 printed circuit boards, pcbs, can be made from a variety of substances. the most widely

7、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. 翻譯：印刷電路板（pcb）可以由多種物質制成。最常用的是某種形式的玻璃纖維板，稱為fr4。這種材料在溫度變化時提供合理的穩(wěn)定度，不容易損壞，而且也不很昂貴。other cheaper materials

8、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 diff

9、icult to work with.翻譯：在低廉的pcb商品中可用其它較便宜的材料。對于高性能的射頻設計，其基底的介電常數(shù)很重要，且需要有低的損耗，可以用基于ptfe（聚四氟乙烯）材料的印刷電路板，但它們在加工時有一定的難度。 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

10、 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. 翻譯：為了制作具有連接元件印刷線的pcb，首先要獲得一塊覆銅板。它由在板的兩面覆上銅的基底材料構成，這個基

11、底材料通常是fr4。所覆的銅是一薄層粘合在板上的銅層，對fr4板這種粘合是非常好的。但是，正是ptfe的特性使得這種粘合更難，這也就增加了ptfe板制作的難度。 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 m

12、ost common form of etch used with pcbs is ferric chloride. 翻譯：選擇好裸的、可用的pcb板之后，下一步是在板上創(chuàng)立所需的印刷線并且清除不需要的銅。pcb的生產通常采用化學腐蝕處理的方式。最常用的腐蝕劑是鐵氯化物。 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.

13、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 co

14、vered in the resist. 翻譯：為獲得正確的印刷線圖案，要用照相技術。通常裸的pcb上的銅層覆蓋著一薄層光阻材料，然后通過膠卷或光掩膜曝光，詳細地顯現(xiàn)出了所要的印刷線印跡。用這種方法，印刷線圖案就印制在光阻材料上。這些完成后，把光阻材料放在顯影劑里，這樣，只有那些需要在板上敷設印刷線的區(qū)域能被光阻材料所覆蓋。 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. kn

15、owing 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. 翻譯：制做過程的下一步是把pcb放在鐵氯

16、化劑中，把沒有印刷線或不需要銅層的地方腐蝕掉。知道了鐵氯化劑的濃度和板上銅層的厚度，就可將pcb按所要求的時間放到腐蝕劑中。如果pcb放到腐蝕劑中的時間太長，圖案的一些輪廓清晰度會消失，因為鐵氧化劑將會切割光阻材料。 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 controll

17、ed 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 prot

18、otype quantities are needed. 翻譯：雖然大部分pcb用照相技術生產，但也可用其它的方法。其中的一種就是用專用的高精度銑床，用機器銑掉那些不需要銅的區(qū)域上的銅。機器的控制顯而易見是自動的，并且由pcb設計軟件產生的文件來驅動。這種方式不適應于大批量生產，而在大多只需要生產小批量樣品時，它是一個理想的選擇。 with the complexity of electronic circuits increasing, it is not always possible to provide all the connectivity that is required usi

19、ng 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.翻譯：隨著電子電路復雜性的增加，僅用雙面的pcb不能滿足所有連接的需求。當設計密集性微處理器及其它相似的板時，尤其是這樣。這時，就需要用多層pcb了。 the manufacture of multi-layer pcbs, al

20、though 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

21、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.翻譯：雖然多層板的生產方法與單層板相同，但是要求有相當高的精度和生產過程控制。板的每層分別用更薄的單獨的板，然后各層板粘合成整塊pcb板。當板的層數(shù)增加時

22、，每層板必須更薄，以免完整的pcb變得太厚了。另外，各層板之間的對齊必須非常精確，以確保任何需要對齊的孔都能對齊。 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 parti

23、cularly if, for example one of the inner layers is a power plane or a ground plane. 翻譯：為了將不同層粘合在一起，印制板被加熱以固化粘合材料。這樣可能導致出現(xiàn)彎曲問題。若設計不當，大的多層板上會有不同的彎曲。例如，若其中一個內部層是電源層或接地層，尤其會發(fā)生這種這情況。 the manufacture of pcbs is an essential element of the electronics production and many new technologies have employed and

24、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. 翻譯：pcb的制造是電子學生產的一個重要要素，并使用了許多新技術，且新技術的使用使得在縮小組件和印刷線的尺寸以及在板的可靠性兩方面都得到了極大的改進。 pcb是非常穩(wěn)定的復合物

25、而不會迅速地降解。 they 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

26、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. 翻譯：它們可被化學的、熱的或生物化學的過程所破壞，但要達到完全的破壞是非

27、常困難的，且通過部分氧化有產生極毒的二苯并二氧化芑和二苯并氧雜茂的危險。因為pcb具有高的熱力學穩(wěn)性，所有難以找到理想的降解機制都。有效處理廢棄pcb的降解方法一般要求高熱或催化作用。對于大多數(shù)其它復合物進行有利于環(huán)境或新陳代謝的降解處理過程也是相當慢。 3.疑難解析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

28、forward. 雖然今天用pcb構成幾乎所有電子電路的基底被認為是理所當然的，然而，在電子學領域這一技術仍在不斷發(fā)展。be taken sth. for granted 意為“ 認為是理所當然的, 認為是不成問題的”。2) 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

29、 smaller smt devices can be handled and the soldering processes used in production can be accommodated. pcb印刷線的尺寸正在減小，板的層數(shù)正在增加以適應所需連通性的提高，設計規(guī)則也正在改進，從而確保能操作較小的表面貼裝技術器件，并適應生產所用的焊接處理。the number of 意為“.的數(shù)量”，后接名詞，其謂語動詞用單數(shù)形式；a number of 意為“一些，若干”；any number of 意為“很多，好多”， 后面都接可數(shù)名詞，謂語動詞用復數(shù)形式。4 語法應用科技英語中的復合詞與縮略詞1) 復合詞：復合詞可由兩個或更多的單獨詞組成。由于作者可任意