静电放电理论基础5

静电放电理论基础和其有效的控制方案WinifredInt’lTechnologyLtd.美商卫利WinifredCopyright20072公司简介美商卫利有限公司是一家制造与销售防静电产品、无尘净化用品以及微生物污染控制与检验产品的专业公司，同时也代理世界著名公司的相关产品，总部设立在香港。九十年代初进入中国大陆开展业务，先后在上海﹑深圳福田﹑深圳福永、天津、无锡﹑苏州﹑成都﹑大连﹑杭州、武汉、厦门、北京、西安、重庆、福州、宁波、广州、青岛、南京、昆山、东莞等地开设25个分公司和办事处,以获取更大的市场份额，保证提供给国内用户最优质的产品和服务。WinifredCopyright20073BasicofElectrostaticDischargePartA:IntroductionofESD–静电放电入门PartB:ESDControlProceduresandProducts–控制静电放电的方式及产品PartC:ESDControlProgram–如何有效的建立静电放电控制方案(ANSI/ESD20.20-1999,2007))Conclusions–总结WinifredCopyright20074PartA:IntroductionofESD1.Historyandnewtrends-历史发展及趋势2.Basics-基本电学3.CreatingCharges–静电产生方式分类4.Electrostaticwillcause-静电造成的影响5.ESD–ElectrostaticDischarge-放电模式6.PhotoExamples-图例WinifredCopyright200751.Historyandnewtrends-历史发展及趋势1960–staticdischargecausedmissileexplosion1970–Federalandmilitaryregulations1980–DevelopingstagesonESDcontrolproductsEarly1990–USAESDAssociations90年代后，电子产品的趋势是:电子产品的功能越来越复杂,体积越来越小,例如在大的液晶屏或者磁头行业,产品所要求自动化生产能力越来越高.因此产品被ESD损伤的可能性不断升高.PartA:IntroductionofESDWinifredCopyright20076PeoplearegettingbetterindealingwithESDissues.Thequestionis:Wouldwegettherefastenough?我们已愈来愈重视静电防护,问题是我们是否方向正确，是否赶的科技发展速度?PartA:IntroductionofESDWinifredCopyright200773.CreatingCharges–静电如何产生A.Tribogeneration–接触摩擦分离起电B.Polarization/Induction-极化/感应起电C.Conduction-传导PartA:IntroductionofESDWinifredCopyright20078PartA:IntroductionofESDA.Tribogeneration-接触摩擦分离起电Positive正极性RabbitFur兔毛Glass玻璃HumanHair毛发Nylon尼龙Wool羊毛Lead石墨Silk丝绸Aluminum铝Paper纸Cotton棉Steel钢Wood木材Nickel,Copper镍,铜Gold,Platinum金,白金Rayon人造纤维Polyester聚酯Silicon硅Teflon聚四氟乙烯Negative负极性WinifredCopyright20079PartA:IntroductionofESDMeansofgeneration静电产生方式10-25%RH(相对湿度)65-90%RH(相对湿度)Walkingacrosscarpet在地毯上走动35,000V1,500VWalkingacrossvinyltile在乙烯基地板上行走12,000V250VWorkeratbench工作人员在工作台上操作6,000V100VPolybagpickedupfrombench从工作台上拾起普通聚乙烯袋20,000V1,200VChairwithurethanefoam坐垫有聚氨脂泡沫材料的工作椅18,000V1,500VWinifredCopyright200710B.Polarization/InductionWhenanungroundedconductivematerialisintheelectricfieldfromanotherobject,itbecomespolarized(chargeredistributed).Whenthispolarizedobjectisgrounded,whilestillinthefield,itretainsastaticcharge.-当一个未接地的传导材料进入另一个物体产生的电场范围内，就会发生极化现象（既电荷的重新分配）。当这个被极化的物体接地时，会发生静电的泄放。PartA:IntroductionofESDWinifredCopyright200711PartA:IntroductionofESDWinifredCopyright200712C.Conduction–传导Conductionisthetransferofchargethroughdirectcontact.Thishappenswhenachargedobjectdirectlycontactsanobjectwithadifferentcharge.Theremustbeaconductivepathbetweentwoobjects.-传导是通过物体直接接触产生电荷移动。它发生在两不同电荷物体间，且两物体间必须具有导通路径。PartA:IntroductionofESDWinifredCopyright200713PartA:IntroductionofESDFactory–staticgeneratorsexistineverywhere-静电无处不在Operators:clothes,shoes,hair,walking,sitting衣服,鞋子,头发,行走,就座Workstation:tabletop,chair桌面,椅子Flooring:carpet,tile,vinyl,concrete地毯,瓷砖,塑料,混凝土Packaging:bags,tapes,trays,foam..包,带子,盒子,泡沫Hardware,handtools,tweezers,solderingirons…仪器部件,工具,镊子,电烙铁Components组件Equipment设备Specialnote:conductors(metaltometalcontacts)导体WinifredCopyright2007144.Electrostaticwillcause-静电造成的影响ESD,therapidtransferofchargebetweenobjectsatdiffferentpotentials,Theenergyofthisfasttransferdissipatesasheat,Meltsomecriticalpartofcomponents,gates,ESA–ElectrostaticAttraction(静电吸附)EMI–ElectromagneticInterference(电磁波干扰)PartA:IntroductionofESDWinifredCopyright200715ESDdamages-静电造成电子产品损害的二个方式A.Discharge:Whentwoobjectswithdifferentchargesarebroughttogether,thechargesmovebetweentheobjectsuntilbothobjectshavethesamecharges.Thisdischargewillproduceenergytodestroypathwaysandgatesinsidecomponents.Itcoulddamageoneitherobjectsthroughthisunwantedandun-controllabledischarge.-电荷泄放：当两个承载不同电荷的导体放置在一起，既会产生电荷移动，直至两者拥有等量电荷。电荷泄放会对组件造成损害。B.Fields:Electroniccomponentsdamagefromfieldsoccursfromeithercurrentinducedintothecircuitorfromdischargeoccurringfromachargedobjectafterpolarization.-电场感应：感应电流形成电路和极化作用后的载荷物体均会对电子组件造成损害。PartA:IntroductionofESDWinifredCopyright200716PartA:IntroductionofESDCatastrophicfailure-立即性伤害(Quality)Parametricalfailure-testokatborderlimits,butthenfailedatstresstest.Latentfailure-潜伏性伤害(Reliability)StaticLossReported,average–静电损失报告Componentmanufacturers:16–22%制造商Subcontractors:9–15%次承包者Contractors:8–14%承包人User:27–33%用户6.5%ofrevenuse–$84Billionannually(USA)from97’to01’Failureanalysis–morethan90%unsolvedfailureareESDrelated,costly.-ESD损伤发生概率大，成本高WinifredCopyright2007175.ESD–ElectrostaticDischarge-放电模式ThreeDischargeModels:三种放电模型Dischargetothedevice:对电器放电Humanbodymodel–人体模型(1960s)Machinemodel–机器模型Dischargefromthedevice:电器放电Chargedevicemodel–带电器件模型(1980s)Theseeventstendtoproducedifferenttypesoffailureandrequiredifferenttypesofcontrolandprotection.-三种模式造成的伤害不同,防护的措施亦不同。PartA:IntroductionofESDWinifredCopyright200718PartA:IntroductionofESDHumanBodyModel(HBM):人体模型Dischargefromachargedhuman(ungrounded)bodytotheESDsensitivedevice.Itwillbeworseifdevicesitsonagroundedconductivesurface.-由未接地的载荷人体向静电敏感器件泄放。尤其当器件放置在接地的导电工作表面。Undercontrolinmostmanufacturingfacilities.Examples:举例说明Handassemblyoperations手工装配操作Circuitpackrepairstations电路包装修理站Componentreceivingare