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《HALT and HASS》由會員上傳分享，免費(fèi)在線閱讀，更多相關(guān)內(nèi)容在學(xué)術(shù)論文-天天文庫。
1、PitfallstoAvoidinHALTandHASSGreggK.Hobbs,Ph.D.,P.E.MuchhasbeenwrittenonwhattodoinHALTandHASS.Whatnottodoshouldalsobediscussedinordertoenforcethepositive.Someofthemostcommonlyoccurringmistakeswillbediscussedanditwillbepointedoutwhyeachisamistake.Themistake
2、isfirststatedinboldtypeandthenisdiscussedverybriefly.Allofthesearecoveredinmoredetailinmytextbook,HALTandHASS,AcceleratedReliabilityEngineering,whichissoldthroughHobbsEngineering.NotperformingSafetyofHASS.Thisisoneoftheworstpossiblemistakesthatcanbemadean
3、dissomewhatequivalenttoplayingRussianRoulettewithseveralcylindersloaded.HighlyAcceleratedStressScreensarequitecapableofreducingtheusablefieldlifeofgoodhardwareifthestressesarechosentobetoohighforthedesignandprocessesunderwhichitisbuilt.IfHALThasbeenproper
4、lydone,thenthisrarelyoccurs.IfHALThasnotbeendoneatallorifthemarginsattainedarenothighenough,thenfieldlifereductionmayoccur.TheonlywaytoreasonablyprovethatthescreensaresafetouseinproductionistorunSafetyofHASS.Ifthisisnotdone,thenthefieldfailureswilldetermi
5、neiftheHASShasbeenproperornot.Clearly,thiswaitandseeapproachisnotagoodwaytofindoutifthescreensaretoointenseas,bythetimeitisrecognizedthatthescreensaretoointense,substantialnumbersofreducedlifeunitswillhavebeenshipped.SafetyofHASSismandatoryforpropertechni
6、que.Notmonitoringwithhighcoverageduringstimulation.Thisisalsooneoftheworstpossiblemistakesthatcanbemadeandusuallyleadstoasubstantialfinancialloss.Whatwillusuallyhappeninthissituationisthatflawswillbeprecipitatedbutnotdetectedandthenthecustomerwillhavefail
7、uresduetoprecipitateddefectssoonafterdeliveryleadingtoaveryunhappycustomerandmanyfieldreturns.Itissuggestedthatifonecannotmonitortheproducttoatleastamodestextentduringstimulationwiththevariousstresses,thewholeideaofHALTandHASSshouldjustbeabandoned.HALTand
8、HASS(aswellasclassicalscreeningandtesting)withoutgoodcoveragearelessthanworthless!CoveragecanbedeterminedandimprovedsignificantlybyperformingSoftwareTMHALT.Notusingacceleratedstressconditions.Ifacceleratedstresscond
