ESD和EOS培训教程

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1、EOS/ESDQ.WhatistheEOS?A.Bydefinition,electricaloverstress(EOS)is“theexposureofanitem(anelectroniccomponent,forexample)toacurrentorvoltagebeyonditsmaximumrating.Thisexposuremayormaynotresultinacatastrophicfailureoftheitem.”Typically,itcanbeinferredthatanoverst

2、resshasoccurredwhenanitemfailstomeetitselectricalcharacteristics.DeterminingwhetherthefailurewascausedbyanESDeventorsomeothertypeofoverstressisoftenmoredifficult.Inaddition,overstressmayresultinlatentdamagetoanitem.Thisdamageisnotimmediatelydetectedinitselect

3、ricalproperties,butcouldresultinafailureoftheitemlater.EOSdueto:ØElectromagneticpulses(EMP)ØElectrostaticdischarge(ESD)ØSystemtransientsØLightningESD/EOSDifferencesEOSESDTypicallygeneratedby:SubsetofEOSqLimitedEnergyqPowersuppliesqUsuallycausedbystaticqTesteq

4、uipmentqEventusuallylastsfrommillisecondqEventlastsfromnanototosecondsmicroseconds•Typically>50uspulseNoteasilyvisibleqGateoxidebreakdownIndications:qJunctionspikingqBlownmetalLinesqLatchupqMoltenDamageNotalwaysrestrictedtoI/OqUsuallyThermalqHighpowerqMaycaus

5、efunctionalfailsEOSCausesandEffectsqInadequateWorkProceduresvHotswitchingInsertion/removalofcomponentswithpoweron/notfullypowereddown.vInadequateTraining.qPoorboarddesignvTransmissionofpulsesfromotherequipmente.g...noiseformswitchmodepowersupplies.qPoortestde

6、velopmentvTestappliessignalsbeforepoweringupchip.vMaximumoperatingconditionsexceeded.EOSControlqWorkProceduresvDocumentedtest/assemblyflows.vCorrectinsertionofdevices-usepictorialreminders.vBewareofpoweredinsertionsandremovals.vCheckconnections.qMaintenance/L

7、ineMonitoringvEquipmentnotgrounded.vLooseconnectionscausingintermittenceevents.vPoorwiremanagement.vNoAClinemonitoring.qBoard/ComponentTestvHotswitching.vIncorrecttestsequence.vExcessivevoltages.vWrongstresstests.vProbing.vPoorboardlayout.qPowerSupplyQualityv

8、Poordesignleadingtonoise.vNoovervoltageprotection.vInsufficientlinefiltering.vWrongfuseandinadequateprotection.ESDModelsØHumanBodyModel(HBM)ØMachineModel(MM)ØChargedDeviceModel(CDM)ESDSys