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J-STD-020DMoisture/ReflowSensitivityClassificationforNonhermeticSolidStateSurfaceMountDevices非密封固态表面贴装元件湿度/回流焊敏感度分级1PURPOSE(目的）Thepurposeofthisstandardistoidentifytheclassificationlevelofnonhermeticsolidstatesurfacemountdevices(SMDs)thataresensitivetomoisture-inducedstresssothattheycanbeproperlypackaged,stored,andhandledtoavoiddamageduringassemblysolderreflowattachmentand/orrepairoperations.本标准旨在识别非密封固态表面贴装元件的湿度敏感等级以便其能合适的封装，储存，作业以避免在回流和维修作业中被损伤.Thisstandardmaybeusedtodeterminewhatclassification/preconditioninglevelshouldbeusedforSMDpackagequalification.Passingthecriteriainthistestmethodisnotsufficientbyitselftoprovideassuranceoflong-termreliability本标准用于判定合格的SMT封装应使用何种等级/预处理水平.依据本测试方法且通过对应判定标准的元件并不能保证其长期可靠性1.1Scope（范围）ThisclassificationprocedureappliestoallnonhermeticsolidstateSurfaceMountDevices(SMDs)inpackages,which,becauseofabsorbedmoisture,couldbesensitivetodamageduringsolderreflow.ThetermSMDasusedinthisdocumentmeansplasticencapsulatedsurfacemountpackagesandotherpackagesmadewithmoisture-permeablematerials.ThecategoriesareintendedtobeusedbySMDproducerstoinformusers(boardassemblyoperations)ofthelevelofmoisturesensitivityoftheirproductdevices,andbyboardassemblyoperationstoensurethatproperhandlingprecautionsareappliedtomoisture/reflowsensitivedevices.IfnomajorchangeshavebeenmadetoapreviouslyqualifiedSMDpackage,thismethodmaybeusedforreclassificationaccordingto4.2.此分类程序适用于所有非密封固体表面贴装元件，此部分元件由于吸收湿气而在回流焊接中容易损伤.本文件所提及的术语“SMD”指的是塑封或本体为吸湿材料的元件.分类的目的是为了让元件制造商能告知元件使用者（PCBA组装）其产品的湿敏等级，确保元件使用者能恰当作业，如果对之前认证过的SMD封装没有重大更改，依据4.2此方法亦可用于元件的再次分类.Thisstandardcannotaddressallofthepossiblecomponent,boardassemblyandproductdesigncombinations.However,thestandarddoesprovideatestmethodandcriteriaforcommonlyusedtechnologies.Whereuncommonorspecializedcomponentsortechnologiesarenecessary,thedevelopmentshouldincludecustomer/manufacturerinvolvementandthecriteriashouldincludeanagreeddefinitionofproductacceptance.此标准不能涵盖所有与设计，组装相关联的元件.但是，此标准为通用技术提供了一个测试方法和标准.如果使用特殊技术或特殊元件，则需客户以及相关的制造方定义一个双方同意的产品接受标准.SMDpackagesclassifiedtoagivenmoisturesensitivitylevelbyusingProceduresorCriteriadefinedwithinanypreviousversionofJ-STD-020,JESD22-A112(rescinded),orIPC-SM-786(rescinded)donotneedtoberevisionunlessachangeinclassificationlevelorahigherpeakclassificationtemperatureisdesired.AnnexBprovidesanoverviewofmajorchangesfromRevisionCtoRevisionDofthisdocument.在使用之前版本J-STD-020，JESD22-A112（已作废），IPC-SM-786（已作废）标准中已分级的湿敏元件除非敏感等级变更或耐温峰值提高，否则无须重新分级.附件B提供了版本C升级到版本D的主要变更.Note:Iftheproceduresinthisdocumentareusedonpackageddevicesthatarenotincludedinthisspecification’sscope,thefailurecriteriaforsuchpackagesmustbeagreeduponbythedevicesupplierandtheirenduser备注：当封装元件未在本标准规格范围内，如需使用此文件中的流程判定，则不良标准需元件供应商和其客户同意.1.2Background（背景）Thevaporpressureofmoistureinsideanonhermeticpackageincreasesgreatlywhenthepackageisexposedtothehightemperatureofsolderreflow.Undercertainconditions,thispressurecancauseinternaldelaminationofthepackagingmaterialsfromthedieand/orleadframe/substrate,internalcracksthatdonotextendtotheoutsideofthepackage,bonddamage,wirenecking,bondlifting,dielifting,thinfilmcracking,orcrateringbeneaththebonds.Inthemostseverecase,thestresscanresultinexternalpackagecracks.Thisiscommonlyreferredtoasthe‘‘popcorn’’phenomenonbecausetheinternalstresscausesthepackagetobulgeandthencrackwithanaudible‘‘pop.’’SMDsaremoresusceptibletothisproblemthanthrough-holepartsbecausetheyareexposedtohighertemperaturesduringreflowsoldering.ThereasonforthisisthatthesolderingoperationmustoccuronthesamesideoftheboardastheSMDdevice.Forwave-solderedthrough-holedevices,thesolderingoperationoccursundertheboardthatshieldsthedevicesfromthehotsolderthrough-holedevices,thesolderingoperationoccursundertheboardthatshieldsthedevicesfromthehotsolderThroughholedevicesthataresolderedusingintrusivesolderingor‘‘pininpaste’’processesmayexperiencethesametypeofmoisture-inducedfailuresasSMTdevices.非密封元件封装在回流高温条件下，其内部水蒸气压力猛增.在某一件下，压力将导致封装从内部分层或者内裂，邦定受损。更为严重的情况下，压力将导致外部封装开裂.此称之为“爆米花”现象，即由于内部压力引起封装膨胀并且伴随“砰，砰”声而裂开.相对于通孔元件，由于SMD元件需更高的温度回流，因此此种情况尤为敏感.其原因为，SMT元件在PCB同一面回流因而受热更多。而对于通孔元件，其通常在在PCB之上，因而避免直接高温。如使用印刷回流制程的通孔元件则可能与出现SMD元件一样失效.1.3TermsandDefinitions(术语与定义）acceleratedequivalentsoak–Asoakatahighertemperatureforashortertime(comparedtothestandardsoak),toprovideroughlythesameamountofmoistureabsorption.Seealsosoak快速浸泡：相对标准浸泡而言，使用更高温度在更短时间内浸泡acousticmicroscope–Equipmentthatcreatesanimageusingultrasoundtoviewaspecimen’ssurfaceorsubsurfacefeatures,includingdefectsanddamage.SeeJ-STD-035formoreinformation.声学显微镜：使用超声波对元件表面和内部特征（包括不良和损伤）进行查看并产生图像的设备areaarraypackage–Apackagethathasterminationsarrangedinagridonthebottomofthepackageandcontainedwithinthepackageoutline.？？classificationtemperature(Tc)–ThemaximumbodytemperatureatwhichthecomponentmanufacturerguaranteesthecomponentMSLasnotedonthecautionand/orbarcodelabelperJ-STD-033依据J-STD-033元件制造商在警告标签物料标签上所标示的元件本体最高耐温.crack–Aseparationwithinabulkmaterial.SeealsoDelamination开裂：元件内部分离damageresponse–Allirreversiblechangescausedbyexposuretoareflowsolderingprofile.损伤反应：由回流引起的所有不可逆的的改变.dead-bug