FMEA-SMT

11.0ProcessFMEA(SurfacemountingoftheSMTcomponent)ProcessStepRiskAssessmentSolderpasteprintingHighChipmountingHighICmountingHighReflowsolderingHigh22.0ProcessFMEARiskpriorityNumber(RPN)tableonsurfacemountingofSMTcomponentsFunctionalorequipmentidentificationFailuremodesFailureeffectsSeverityFailuremechanismOccurrenceFailuredetectionDetectionCorrectiveactionsRPNRPNScreenprintsolderpasteSolderbridgeVisualinspectionreject5Stencilapertureopeningtoobig3Visualforsolderbridging345Reductionontheapertureopening.RefertolatestDGdesign.Buyoffstencilbeforeuse.Metalmasktensionloose3Visualforsoldersmearing345Developmeasuringmethod&frequencytoensurestencilisingoodconditionSqueegeebladewornout3Visualforsoldersmearing345Changesqueegeebladeafter10,000printsSqueegeedownstopandpressuretominimumsetting–justenoughtohaveacleansweep3Cont.FunctionalorequipmentidentificationFailuremodesFailureeffectsSeverityFailuremechanismOccurrenceFailuredetectionDetectionCorrectiveactionsRPNRPNNosolderICTtestdetectedfailed5Stencilopeningclogged6Visualformissingprint390Re-softensolderpasteonstencileveryhourly.Timesetting:1minutesUseautomaticsolderpastesoftenermachineInsufficientSolderpasteonthestencil6Visualformissingprint390Maintainsatleast10mm“hotdog”rollingeffectInsufficientsolderICTtestdetectedfailed8Squeegeepressuretoohigh3LSMthicknessmeasurement6144Squeegeedownstopandpressuretominimumsetting–justenoughtohaveacleansweep4FunctionalorequipmentidentificationFailuremodesFailureeffectsSeverityFailuremechanismOccurrenceFailuredetectionDetectionCorrectiveactionsRPNRPNChipshootingMisalignment25%VisualInspection5SkippedPCBfiducial33XVisualinspectionformisalignment345SMTEngineeringtoensureplacementprogrammedwithPCBfiducialmarkson.IndividualX-Yteaching33XVisualinspectionformisalignment345SMTEngineeringtouseoriginalCADdataforNCprogram.Individualteachingisnotallowed.Onlypatternoffsetisallowed.MissingcomponentVisual5Vacuumsensordirty3Visualinspection345Weeklymaintenancefornozzle#15FunctionalorequipmentidentificationFailuremodesFailureeffectsSeverityFailuremechanismOccurrenceFailuredetectionDetectionCorrectiveactionsRPNRPNICPlacementMisalignment25%QFPVisualInspection5Skippedlocalfiducial33XVisualinspection375SMTEngineeringtoensureall20milQFPplacementsprogrammedwithlocalfiducialmarks.QFPSolderbridgeVisualInspection5Pressedtoohardwhenplacing33XVisualinspection575Alterplacementheightuntilnodepression.MissingcomponentVisual5Vacuumsensordirty3Visualinspection345WeeklymaintenanceSetprevacuumcheckto16FunctionalorequipmentidentificationFailuremodesFailureeffectsSeverityFailuremechanismOccurrenceFailuredetectionDetectionCorrectiveactionsRPNRPNHotairreflowComponentthermalshockICT/FTtestdetectedfailed8Causedbyhighpre-heatramprate3Defectivecomponent372Maintainspre-heatrampratebelow3ºC/secMid-chipsolderballsVisualinspection5Causedbyhighpre-heatramprate3Visualinspectionforsolderballs345Maintains60secminimumfor100ºCto150ºCPoorWettingICT/FTtestdetectedfailed5Causedbyinsufficientheatappliedtothejoints3Opencircuit690Thermalprofilingshalltagtothecoolestpointoftheboard/componentMaxpeaktemp235ºCat215ºC15sec73.0Severity(R)Severityisanassessmentoftheseriousnessoftheeffectofthepotentialfailuremodetothecustomer.Severityappliestotheeffectonly.Ifthecustomeraffectedbyafailuremodeistheassemblyplantortheproductuser,assessingtheseveritymaylieoutsidetheimmediateprocessengineer’steamfieldofexperienceorknowledge.Inthesecases,thedesignFMEAdesignengineer,andorsubsequentmanufacturingorassemblyplantprocessengineershouldbeconsulted.Severityshouldbeona“1”to“10”scale.EffectCriteria:SeverityofEffectRankingRemarksHazardouswithoutwarningMayendangermachineorassemblyoperator.Failurewilloccurwithoutwarning10HazardouswithwarningMayendangermachineorassemblyoperator.Failurewilloccurwithwarning9VeryhighMajordisruptiontoproductionline.100%oftheproductmayhavetobescrapped.8HighMinordisruptiontoproductionline.Productmayhavetobesortedandaportion(lessthan100%)7ModerateMinordisruptiontoproductionline.Aportion(lessthan100%)oftheproductmayhavetobescrapped(nosorting).68EffectCriteria:SeverityofEffectRankingRemarksLowMinordisruptiontoproductionline.100%ofproductmayhavetobereworked.Customerexperiencesomedissatisfaction5VeryLowMinordisruptiontoproductionline.Theproductmayhavetobesortedandaportion(lessthan100%)reworked.Fit&finish/squeakrattleitemdoesnotconform.Defectnoticedbymostcustomers.4MinorMinordisruptiontoproductionline.Aportion(lessthan100%oftheproductmayhavetobereworkedonlinebutoutofstation.3VeryminorMinordisruptiontoproduction.Aportion(lessthan100%)oftheproductmayhavetobereworkedonlinebutinstation.2NoneNoeffect194.0Occurrence(O)ProbabilityofFailurePossiblefailureratesRankingVeryhigh:Failureisalmostinevitable1in21in3109High:generallyassociatedwithprocessessimilartopreviousprocesseswhichhaveexperiencedoccasionalfailuresbutnotinmajorproportions1in81in2087Moderate:Generallyassociatedwithprocessessimilartopreviousprocesseswhichhaveexperiencedoccasionalfailures,butnotinmajorproportions.1in801in4001in2,00065410Probabil