Product-Reliability-introduction

I-YuanChenProductReliabilityIntroductionPage2ExcelYourIdeatoSiliconProductReliabilityIntroduction1.ReliabilityConceptsIntroduction.2.AcceleratedTestingMethodsandTheory.3.FailureRateCalculation.4.ICProductReliabilityTestItems.5.InformationforpreparingHTOLboardandTHB/HASTtestboard.6.RA’stestEquipmentCapacity.Page3ExcelYourIdeatoSiliconQualityandReliabilityQuality:Themeasureofaproduct’sconformancetosomeestablishedcriteria.Statedinanotherway,qualityanswersthequestionofwhetheraproductdoesordoesnotmeetapplicablespecificationsnow.Reliability:Themeasureofaproduct’slifeexpectancy.Statedinanotherway,reliabilityanswersthequestionsofhowlongtheproductwillcontinuetomeetthespecification.QUALITYisacurrentmeasurementandRELIABILITYisalong-termmeasurement.Thedifferencebetweenthemis“TIME”.Page4ExcelYourIdeatoSiliconICProductReliabilityTrendICproductreliabilitytrend:SIA’sreliabilityroadmap:0.25um~10FITs.0.1um~2FITsPage5ExcelYourIdeatoSiliconICProductReliabilityEvaluationICproductreliabilityevaluationlevel:Devicereliability:Reliabilityevaluationonadevicelevel.Productreliability:Reliabilityevaluationonaproductlevel.HowtoevaluatethereliabilityofICproducts:Throughacceleratedlifetesting.Itisalifetestinwhichthestresslevelappliedexceedsthatneededinpracticaluseinordertoreducethetimerequiredtoobservethestressresponseoftheitem.Thestresslevelmaybeincludethermal,electrical,mechanicalandhumidity.Page6ExcelYourIdeatoSiliconBathtubcurveOvermanyyears,andacrossawidevarietyofmechanicalandelectroniccomponentsandsystems,peoplehavecalculatedempiricalpopulationfailureratesasunitsageovertimeandrepeatedlyobtainedagraphsuchasshownbelow.Becauseoftheshapeofthisfailureratecurve,ithasbecomewidelyknownastheBathtubcurve.(I)(II)(III)WeibullExponentialLog-normal/Weibull~1yearOperationTime10yearSteadystatePage7ExcelYourIdeatoSiliconBathtubCurveBathtubcurve:TypicalfailureratecurveofICproducts.RegionI:Infancyperiod.Thefailureratedecreasesrapidly.Infantmortalityfailure,whichiscausedbydefectsindesignormanufacturing.Weibulldistributionmodelfitsthisperiodwell.RegionII:Usefullifeperiod.Thefailurerateisconsideredconstant(steadystate).Randomfailure,whichiscausedbyEOSortemperaturefluctuation,etc.Exponentialdistributionmodelfitsthisperiodwell.RegionIII:Wear-outperiod.Thefailurerateincreasesrapidly.Wear-outfailure,whichiscausedbyfatigue,aging,etc.Lognormal/Weibulldistributionmodelfitsthisperiodwell.Page8ExcelYourIdeatoSiliconBathtubCurvePage9ExcelYourIdeatoSiliconWear-outMechanismsPage10ExcelYourIdeatoSiliconAcceleratedTestingMethodsandTheoryPage11ExcelYourIdeatoSiliconObjectiveandConsiderationItisimpossibletoevaluatethereliabilityofICproductwithnormaloperationconditions.Itwilltakealongtimeandit’simpractical.HowtoapplyaminimumsamplesizeandshortesttimeperiodtoevaluateICproductreliabilityiscrucial.Throughacceleratedtest,wecanevaluatethereliabilityofICproductwithminimumsamplesizeandshortesttimeperiod.Somekindofaccelerationtestsstimulateoraccelerateallthepossiblestresses,includingthermal,electrical,humidity,etc.Page12ExcelYourIdeatoSiliconTemperatureAccelerationFactorTemperatureaccelerationfactor(TAF):DerivedfromArrheniusmodel.Arrheniusequation:whereR=Reactionrate.R0=Reactionrateconstant.Ea=ThermalactivationenergyineV.k=Boltzmann’sconstant(8.62x10-5eV/K).T=inabsolutetemperature(°K).kTEaexpRR0Page13ExcelYourIdeatoSiliconTemperatureAccelerationFactorThelifetimeLisexpressedasfromwhichthetemperatureaccelerationfactorcanbederivedas:whereLnormalandLstressarelifetimesatnormalandstressconditions.TnormalandTstressareabsolutetemperatureatnormalandstressconditions.Thentheactivationenergycouldbeeasilyobtainedfromso-calledArrheniusplot.kTEaexpALstressnormalstressnomralAFT1T1kEaexpLLTstressnormalstressnomralT1T1LLlnkEaln(t)ln(LNORMAL)ln(LSTRESS)1/TSTRESS1/TNORMALTSlopeofthestraightline=Ea/kPage14ExcelYourIdeatoSiliconTemperatureAccelerationFactor–Example:•Takeoperatingconditiontemperatureis55℃.•Takestressoperatingconditiontemperatureis125℃.•AssumethermalactivationenergyEais0.7eV.•Boltzmann’sconstantis8.62x10-5eV/K.Thenweget:=Tnormal=55℃=55+273=328°K,=Tstress=125℃=125+273=398°K.=TemperatureaccelerationfactorTAF=exp[Ea/kx(1/Tnormal-1/Tstress)]=exp[0.7/8.62*10-5x(1/328-1/398)]=77.82Page15ExcelYourIdeatoSiliconElectricalFieldAccelerationFactorElectricalfieldaccelerationfactor(EAF):EAFcanbederivedfromtheEyringmodelandbeexpressedas:EAF=10β(Estress-Enormal),whereEnormalandEstressareelectricalfieldsatnormalandstressconditionsinMV/cm.βistheelectricalfieldaccelerationrateconstantincm/MV.Likewise,βcanbeobtainedfromtheso-calledEyringplot.log10(LNORMAL)log10(LSTRESS)ESTRESSENORMALESlopeofthestraightline=βRemark:SomepeoplealsowriteEAFasEAF=eβ(Estress-Enormal),theprincipleisthesame,butthevalueofβwillbedifferent.Page16ExcelYourIdeatoSiliconElectricalFieldAccelerationFactorExample:AgivenICproductisoperatingatVcc=3.3Vwithoxidethickness=66Å.Takenormaloperatingconditionvoltageis1.1Vcc.Takestressoperatingcondit