华为工艺可靠性设计方法与实践ppt课件

工艺可靠性设计方法与实践华为公司工艺可靠性研究业务介绍,工艺基础研究部工艺可靠性研究组20061124,Page2,目录,工艺可靠性业务的需求分析工艺可靠性业务行业分析工艺可靠性业务组织流程工艺可靠性业务技术内容工艺可靠性技术在产品中的应用案例,Page3,产品中工艺可靠性需求,HighPerformanceSystems1025年的使用寿命对工艺可靠性设计的要求；高频、高速信号；热可靠性问题高复杂度单板；封装技术的极限化发展带来的失效。MidRangePerformanceElectronics5年以上使用寿命；混合组装；无铅可靠性问题。Hand-held/WirelessElectronics4年以上使用寿命；振动、冲击等特殊应用环境；高密；无铅可靠性问题；低成本问题。,Page4,工艺可靠性行业分析业界趋势分析：ECTC、SMTA近年来在工艺可靠性领域的研究,1、不同表面处理条件下的脆性断裂问题；2、快速可靠性评估方法研究；3、无铅、密间距焊点可靠性研究；4、腐蚀与迁移失效机理研究；5、无损分析和故障诊断技术。,业界采用仿真、可靠性试验以及失效机理的研究方法对典型的板级互连可靠性问题进行研究，包括：,Page5,ReliabilityEngineering,FEM,Page6,业界常见可靠性业务流程,DesignVerification,FailureanalysisRootcauseanalysis,results,Predictions/failures,Manufacturerock-likecolumnmainlyContainsNi-Sn-Cu,Results,EDSindicatesNi-Sn-Cuternarycompound,Theydoexist!,Page22,Ifcopperexistinethersideofsolderjointorinsideofsolderjoint,ternarycompoudwillformuponnickellayer!,Results,Theyevenexistinalmostallkindsofsolderjoint!,Page23,Results,Itseemslikethis:,SnPb,NiAu,HASL/OSP,SAC,NiAu,Any,evenNiAu,reflow,Ni-Sn(Cu),Ni-Sn-Cu,Page24,Discussion,Whycoppercanmigratesolongdistance?Copperissoactivewithmuchsolubilityintin.CoppercanformCu-SnIMCmoreeasilyandquicklythanNi-Sn.,Atthetouchsecond,greatmanycopperdiffuseintomeltsolderevenexceedstablesolubility,Duetounstable,somecopperatomcomebacktodecreaseenergy,Coppermigration,Touchmeltsolder,reflow,Coolingbegin,IMCnucleateatinterfaceandternaryIMCforms,Page25,1000 x,3000 x,Hollowhexagon,HollowhexagonCu6Sn5,3000 x,2000 x,solidtrigon,solidhexagon,Discussion,Variablemorphologyofternarycompound,sometimeslikeCu6Sn5,Lookssimilar!,Page26,Sothecolumncanbeidentifiedas(CuNi)Sn5,(a),(b),Diffractionpatternof(a)Cu6Sn5binarycompound(b)column-liketernarycompoundfoundinsolderjoint5,Discussion,Thecrystalstructureofrock-likecolumnisclosetoCu6Sn5,Page27,FieldfailureofBGAsolderjointcrack,foundtrigonandhexagonrockatfracturesurfacewithoutanyetching,Discussion,Somesolderjointfailurecasesshowabnormalbrittlefracture,1000 x,Canternarycompoundbesoterrible?,Page28,TopsideBGAsolderjointcrackafterwavesolder,foundmorestrongtrigonandhexagonrockatfracturesurface.,Somesolderjointfailurecasesshowabnormalbrittlefracture,Discussion,1000 x,Isternarycompoundatroublemaker?,Page29,Discussion,ItseemsthatcrackdevelopbetweentwoIMClayers,Ni-Sn(Cu)andNi-Sn-Cu！,Yes,theredoexistmicrocracksinIMClayer!,Ni-Sn(Cu),Ni-Sn-Cu,5000 x,Page30,Discussion,Failurejointternarycompounddidntshowanydifferencetoothers,Buttherealsoexistevidencetoprovehisinnocence.,FracturedidntoccurinIMCbutatinterfacebetweensolderandIMC,Page31,Discussion,Howaboutothercompanies?,Page32,Discussion,Howaboutothercompanies?,InterfacialfailurebyScompany,dewetfailurebyScompany,InterfacialfailurebyUIC,Page33,Conclusion,whencopperexistinsideoratethersideofsolderjoint,Ni-Sn-Cuternarycompoundwillformatinterfacebetweennickelandsolder.TheNi-Sn-Cuternarycompoundhavetwolayers,Ni-Sn(Cu)and（CuNi）6Sn5,theformeriscontinuousanddensegranularsand-like,andlaterisdiscontinuouscolumnlike.thebondingstrengthofthetwolayercompoundmightnotgoodenough,andsometimescanleadtomicrocrack,butalmostnevercausesolderjointopeninthisway.Somecompanyfoundsolderjointbrittlefractureandattributedittoternarycompound,buttheredoexistcontraryopinionsandmanyexperimentresultdontshowanyweaknessofternarycompound.UICplantodoafullresearchandwecanparticipate.,AssessmentonReliabilityof1.0mmpitchBGAPackagedouble-sideassembly,HUAWEITECHNOLOGIESCo.,Ltd.,ProcessReliabilityResearchGroupofAATCBoardDesignEngineeringDept.20061124,Page35,OUTLINE,OverviewReliabilityTestSampleDesignReliabilityTestresultsSimulationAnalysisConclusion,Page36,Overview,Advantage:layoutsimple,Optimumrouting,noiseisolation,shortenlinelengthProblem:rework,longreliability,Page37,ReliabilityTest,BGAPackageandPCBTestboard,1.0mmpitch2525mm256solderballs,1.6mmPCBOSPsurfacefinishCommonTgmaterial,Page38,ReliabilityTest,BGAAssembly,Double-sidemirrorassembly,Double-sideoffsetassembly,Page39,ReliabilityTest,Testsample,240C,Page40,ReliabilityTest,ThermalCyclecondition,1hourpercycle,15mindwelltime,200failurecriterion,Page41,ReliabilityTest,Reliabilityresults,SinglesideSnAgCusolderjointshavethestrongestreliabilityDouble-sidemirrorassemblydecreasethelifebyhalfDouble-sideoffsetassemblywillimprovethereliability,butdependonthedistanceofoffset,Page42,ReliabilityTest,Failureanalysis,CrackinitialfromthesolderjointsofcornerRedmeanssolderjointopenentirelyGreenmeanssolderjointfailinelectricfunction,butnotseparatefromPCB,Page43,SimulationAnalysis,MaterialProperty,ImplicitCreepModel,Page44,SimulationAnalysis,Crackgrowthmodel,ForSn63Pb37,Darveauxmodel:,ForSnAgCu,Syedmodel:,Page45,SimulationAnalysis,FiniteElementModel,diagonal,Geometrysketch,Singlesideassembly,Page46,SimulationAnalysis,FiniteElementModel,Doublesidemirrorassembly,Doublesideoffsetassembly,Page47,SimulationAnalysis,FEMResults-dangerouspoints,Singleside,Doubleside,Initialcracklocationhavedifferentforsinglesideanddoubleside,Page48,SimulationAnalysis,FEMResults-Estimationlife,failurelocationbyFEMpredictionissametoexperimentalresultspredictionlifehaveagoodcorrelationwithexperimentalresults,Page49,Conclusion,ForPCBAstructureusinginATCexperiments,wefound:forallassemblyshape,thefirstcrackwillinitializefromsolderjointofcorner;forSnAgCualloy,doublesidemirrorwillreducelifebyover3timescomparedwithsingle-sidewhetherbyusingexperimentorFEM;whileforSnPballoy,FEManalysisshowthereductiondegreewillincreasemore;DoublesideoffsetassemblyshapewillincreasethesolderjointsreliabilitytosomeextentwhichdependonthedistanceofoffsetReasonsofsolderjointsreliabilityreductionforBGAdouble-sideassemblymaybeincludepackagestructure,solderalloy,PCBthickness,offsetdistance,andsoon，thesefactorswillinteract.,Page50,DSPC6203器件工艺失效分析,整机测试功能信号时断时续，用手轻轻按压或者开机一段时间故障现象会暂时消失之前曾经出现过此类失效，二者的故障现象和失效定位几乎完全一致，当时的给出的结论是在拿板的时候该处DSP器件是承受外力最大的位置，从而容易造成失效。如此相似的失效现象重复出现，有必要进行更加深入的分析，以确定起失效的根本原因。,Page51,无损检测分析XRay分析,最初的故障定位在U21位置芯片的A1角附近，对该芯片A1附近区域进行XRay分析，结果如图1所示。发现除了存在较多的气孔，没有其他的异常现象。,Page52,无损检测分析IV曲线,重点对BGA器件的四边引脚进行分析AA19和W22开路，AB21和W21时断时续。,Page53,无损检测分析ERSASCOP分析,芯片AB22位置角附近存在多处焊点的开裂现象，裂纹产生在器件侧焊盘同焊料球之间，当在该芯片处施加外力或者热应力的情况下，裂纹可能会暂时的愈合或者断开，因此，功能测试表现出时断时续的现象。,Page54,有损检测分析起拔试验,几乎所有焊点的断裂面都在器件侧焊盘与焊料球之间断面光滑平整，属于脆性断裂AB22角部分焊点端面颜色发暗，应该为断裂面在空气中曝露,Page55,SEM显示断口为脆性断口,Page56,韧性断口图象（推力试验）,Page57,一个正常焊点起拔后的各种断面位置,一般断面在焊料球中间或者是由于器件侧和PCB侧的焊盘从基板脱离,Page58,有损检测分析切片,器件侧焊盘为ENIG镀层个别焊点器件侧出现的裂纹裂纹产生在Ni层/IMC之间，并几乎贯穿整个界面。裂纹的宽度为24微米左右。,裂纹在Ni层/IMC之间产生并扩展,Page59,有损检测分析切片,时断时续焊点器件侧出现明显裂纹,所有焊点PCB侧连接正常,Page60,SEM,时断时续焊点器件侧裂纹背散射图象,所有焊点PCBIMC背散射图象,Page61,有损检测分析SEM和EDX,能谱分析的结果显示了断面Ni层的P含量过高。一般来说业界通用的标准认为ENIG焊盘Ni层中P的含量在9wt10wt左右为宜。而从图中可以看出该批次器件样品的P含量已经达到了20wt25wt。断面P含量超高,Page62,有损检测分析线扫描,Page63,有损检测分析线扫描,从线扫描的结果看出，在Ni/SnPb的界面位置出现了大约一个微米厚度的P的峰值，说明在该层面存在着P富集的现象解释：在焊点服役过程中界面处IMC不断生成和长大，会不断的消耗界面附近两侧的Ni和Sn，这就使原本P含量偏高的Ni（P）层在靠近IMC的地方形成含量更高的富P层；同理，IMC的另一侧会形成一个富Pb的区域。富P层的形成会造成焊点界面的严重弱化，在工艺操作或运输过程中即使是受到一些微小的应力，也容易导致器件焊盘从焊点脱离。,Page64,改进措施,短期解决措施：尽量减少单板加工过程中的热过程（比如减少回流焊液态以上温度时间，降低峰值温度等）减小扣板在装配环节的受力，如规范操作、使用工装后续新单板设计使用到该器件，需要确认不能布局在高应力区域，例如螺钉附近、扣板连接器附近、板边等。根本解决措施敦促加强DSPENIG镀层工艺过程的控制敦促尽快进行DSP基板表面处理方式的改进（由ENIG镀层工艺转变为OSP镀层工艺）,Page65,附：黑盘判断依据4X方法,Page66,外观检查,市场返