手工焊接培训教材(7)ppt课件

1、EET 3124 Soldering 焊接Elements of Project Design, Analysis and Fabrication by Machine MethodsPCB Soldering 电子线路板焊接wRead Chapter 17wSoldering alloying between solder and the metal parts between which an electrical connection is formed.Soldering Methods焊接方法wSeveral Methods of SolderingwHand 手工焊接wDip浸焊w

2、Wave波峰焊接wInfrared Re-flow 红外线回流焊接wVapor Phase 热风回流焊接Solder Composition 焊料wSolder used in electronics is an alloy of tin and lead. 电子产品焊料是锡铅合金。wThe amount of tin ranges from 50 to 70%.锡所占比例为50% 到70%。wThe ratio determines the strength, hardness and melting point of the solder.w锡所占比例决议焊点的强度、硬度和熔点。Solde

3、r Melting Point Graph熔点固体形状液体形状熔融形状Solder Composition Cont.焊料wThe most common tin/lead ratio is 60/40.最常见锡铅比例为60/40。wEutectic solder has a tin/lead ratio of 63/37 and has almost no plastic transition state.共晶焊锡之锡铅比例为63/37，几乎没有熔融形状。wDifferent ratios can be selected based on specific needs.根据需求可选择不同比例

4、。Solder Alloying 焊接合金wWhen solder melts onto a PCB connection, a thin film of metal is dissolved from the copper surface. 当焊锡在PCB焊盘上融化时，铜金属外表会有一层薄膜融解；wThis copper/solder mixture forms an alloy and establishes an electrically continuous joint.这个铜/焊锡构成合金并成为稳定的电气衔接。Solder Forms 焊锡外形wSolder is available

5、 in the following forms:wWire spools 锡丝轴装wBars锡条wSheets锡片wPellets锡球wWasher and other specialized shapesw锡制垫片及其它特殊外形Solder Forms Cont.焊锡外形wFor hand soldering, wire solder comes in ranges of 0.030 to 0.090 in diameter. 对于手工焊接，焊锡丝直径介于0.030 to 0.090 0.762 mm to 2.286 mm wMost solder wire is available wi

6、th a core containing flux. 多数焊锡丝均有内孔Flux 助焊剂wFlux is used to remove oxidation from the surface to be soldered.w助焊剂用于除去焊接外表的氧化物。wThe flux removes the oxides from the metal surface and suspends them in solution where they float to the surface during the soldering process.w助焊剂除去金属外表的氧化物，并在焊接过程w中将之移至焊点外

7、表。Flux Cont. 助焊剂wFlux is corrosive and if left on the surface of the PCB, will deteriorate the conductor surfaces and reduce the resistance of the insulation between soldered connections.w助焊剂具有腐蚀性，残留在PCB外表会使导体蜕变，并降低焊点间的绝缘性能。wThis corrosive action can also damage components.w助焊剂腐蚀性对元器件也有危害。Flux Cont.

8、助焊剂wThere are three major classifications of flux:wChloride (inorganic salts)氯化物 无机盐wOrganic (acids and bases)有机物wRosin松香/树脂wChloride and Organic fluxes are highly reactive at room temperature and are therefore not recommended for use in electronic construction.w氯化物、有机物助焊剂在室温下活性很强，普通不w用于电子产品制造。Flux

9、Cont.助焊剂wRosin core fluxes are used almost exclusively for electronic construction.w松香基助焊剂大多公用于电子产品制造。wRosin core fluxes are non-corrosive at room temperature.w松香基助焊剂在室温下没有腐蚀性。wRosin core fluxes are corrosive at soldering temperatures.w松香基助焊剂在焊接温度下具有腐蚀性。Flux Application 助焊剂运用wLiquid flux can be appl

10、ied by:wWiping 擦拭wDipping 浸渍wSpraying 喷雾wSponging 用海绵揩拭wFoaming 发泡Flux Application Cont.助焊剂运用wPaste flux can be applied by:wWiping 擦拭wBrushing 刷wRosin core solder uses flux that melts upon heat application during the soldering process.Flux Removal 去除助焊剂wAfter the soldering process is complete, the f

11、lux must be removedwImproves appearance w改善外观wEliminates possible corrosion problemsw防止能够的腐蚀问题wLess chance of electrical leakagew减少漏电时机Flux Removal Cont.去除助焊剂wSome techniques for flux removal are:wUse of flux remover sprays w助焊剂清洗剂wBrushing with denatured alcoholw用非饮用酒精刷洗wDipping PCB assembly into a

12、 solvent solutionw将PCBA浸入清洗液wUltrasonic equipment 超声波清洗设备The Soldering Iron 烙铁wThe soldering iron consists of 4 basic parts:wTip 烙铁头wHeating Element 加热单元wHandle 手柄wPower Cord 电源线The Soldering Iron Cont.烙铁wSoldering irons are selected based on:wSize and style of tipw尺寸和烙铁头外形wTip materialw烙铁头资料wRequir

13、ed tip temperature w要求的烙铁头温度wTip temperature recovery time.w烙铁头温度恢复时间Tip Selection烙铁头选择wSoldering iron tips come in many styles.wTips are selected on the basis of personal preference and the goal of providing the largest contact area to the area to be soldered while minimizing the possibility of hea

14、t damage to surrounding leads and components.w烙铁头选择根据焊盘大小、零件大小、焊接温度、元器件对温度的敏感性、个人喜好等。Tip Types烙铁头外形wChisel & Pyramid Used for hand wiring and general repair work. Allows large areas to be heated rapidly.w凿子、棱椎形用于线材焊接和普通的修缮任务。可以使较大区域迅速加热。wBevel Used for soldering terminal pad connections on singl

15、e sided boards.w斜角形用语焊接单面板上的接线端焊盘。Tip Types Cont.烙铁头外形wConical Used for high density wiring and heat sensitive parts.w圆锥形用语焊接微小间距和温度敏感元器件。wRadius Groove - Used on round components.w半凹槽形用语圆形器件。Tip Types Cont. 烙铁头外形Soldering Iron Temperature烙铁温度wA tip temperature of 600 to 900 degrees F is sufficient

16、for general purpose soldering.w烙铁头温度600到900华氏度316到482摄氏度可以足够满足普通的焊接需求。wSoldering irons are rated in watts. They are typically available from 15 to 60 Watts.w烙铁功率普通为15到60瓦。Soldering Iron Temperature Versus Wattage烙铁温度/功率Soldering Iron Tip Color Versus Temperature烙铁头颜色/温度Hand Soldering 手工焊接wBoards mus

17、t be clean to begin with, especially if theyre not previously tinned with solder. Clean the copper tracks using e.g. an abrasive rubber block and clean with denatured alcohol.w首先必需保证PCB干净，特别是没有预镀锡的板。可以运用橡胶擦子或者非饮用酒精清洁PCB。Hand Soldering手工焊接Hand Soldering手工焊接wClean the iron bit (tip) using a damp spong

18、e. Iron featured is an Ungar Concept 2100 Soldering Station. 运用潮湿海绵清洁烙铁头。Hand Soldering手工焊接wInsert components and bend the leads so that the part is held in place. w插入元件，将w管脚折弯以固定w元件。Hand Soldering 手工焊接wIts usually best to snip the wires to length prior to soldering. This helps prevent transmitting

19、mechanical shocks to the copper foil. w通常最好的做法是w提早将零件脚剪至w需求的长度。w这可以预防对铜箔w的机械冲击。Hand Soldering 手工焊接wApply a clean iron tip to the copper and the lead, in order to heat both items at the same time. w务必坚持烙铁头w干净，并同时接触w加热元件脚和焊盘。Hand Soldering 手工焊接wContinue heating and apply a small amount of solder. Remo

20、ve the iron and allow the solder joint to cool naturally.w继续加热，并放入w少量锡丝。移开烙铁w以使焊点自然冷却。Hand Soldering 手工焊接wIt only takes a second or two, to make the perfect joint, which should be nice and shiny.w只须12秒钟焊点w就可以构成。w良好的焊点应该w整洁亮堂。 Solder Defects 焊接缺陷wSolder Peaking - Sharp point of solder protruding from

21、 a connection.wRapid removal of heat prior to solder becoming completely melted to liquid stage.w锡尖w在焊锡未完全熔化成为液体形状之前快速移开烙铁所致。Solder Defects Cont.焊接缺陷wIncomplete wetting Alloying process not completed.w未润焊合金过程未完成wUsually the result of insufficient heat and/or solder. w通常由加热缺乏或者焊锡缺乏导致。wMay also occur

22、if contamination is on the terminal pad or soldering iron tip.w也能够由于焊盘或者烙铁头污染所致。Solder Defects Cont.焊接缺陷wExcessive solder lead contour not completely visible. 多锡包焊- 元件脚周线不可见。wReduce the amount of solder appliedw减少用锡量wCold solder joint dull-gray, grainy appearance.w冷焊锡点呈暗灰色，外表粗糙。wResult of insufficie

23、nt heat.w加热温度缺乏导致。Solder Defects焊接缺陷wAn example of a dry joint - the solder failed to flow, and instead beaded to form globules around the wire. Solder Defects Cont.焊接缺陷wTenfold excess of solder, and (extreme left) incomplete joint with poor coverage. There is no need to add more solder for luck. So

24、lder Defects Cont.焊接缺陷wOne example of several dry joints found within a commercial PSU adaptor for a computer peripheral. Solder Defects Cont.焊接缺陷wA close-up reveals the terrible standard of soldering (and quality control), with a fracture visible on this ground/ earth joint. De-soldering PCBs 去锡解除焊

25、接wSeveral aids to use for de-solderingwSolder wick 吸锡芯绳wSolder sucker吸锡器wDe-soldering bulb 去锡灯泡wDe-soldering tips 去锡尖头wExtraction Tools 抽吸工具wVacuum de-soldering station 真空去锡任务台De-soldering去锡wThe two solder joints to be de-soldered, to enable a faulty component to be removed. De-soldering Cont.去锡wIf

26、using a de-soldering pump, apply the iron first to melt the solder (1-2 seconds). w假设运用吸锡器，w先用烙铁使w锡熔化。w12秒De-soldering Cont.去锡wThe nozzle of the de-soldering pump is applied to the molten solder and the spring-loaded plunger is then released, drawing the solder up into the pump. Repeat if needed. w吸

27、锡器吸嘴对准熔化的焊锡，释放弹簧活塞w，吸走焊锡。可反复进展。De-soldering Cont.去锡De-soldering Cont.去锡wThe first joint, now de-soldered. The second joint will be de-soldered using braid.De-soldering Cont.去锡wSelect a suitable width of braid编织, and press it down onto the COLD joint using the hot tip of the iron. De-soldering Cont.去

28、锡wMolten solder is drawn up by capillary action into the braid. Care not to overheat, or drag whiskers of solder over the board, nor let the braid solidify on the joint! w毛细管吸附作用De-soldering Cont.去锡De-soldering Cont.去锡wThe component dropped out of the board after de-soldering. Sometimes, it may need

29、 persuading with pliers 钳子. De-soldering Cont.去锡wClose-up shot of both joints, now de-soldered and ready for the replacement part to be fitted. Dip Soldering 浸焊wPCB is physically dipped into a molten pot of solder.wBoard is cleaned and then fluxed prior to dipping.wPCB预先上助焊剂。wUsually dipped by hand.Solder Pot Examples 锡炉Wave Soldering 波峰焊接wA conveyor syst