Phil
WelcometoBoardTalk.WearetheAssemblyBrothers,PhilZarrowandJimHallofITMConsulting,we’reheretoansweryourquestionsonSMTprocesses,equipment,materials,andprocedures.Whatisinourmailbagtoday,Jim?
Jim
TodaywehearfromHM.”IknowaboutvoidsinBGAsolderjoints,butisthereaqualitycriteriaforthesoldervoidsinpassivecomponents,includingresistors,capacitors,etc.?”
Phil
Whenwelookatthesespecs,we’rebasicallycomparingcontractareavoidswiththingslikemisalignments,skewedcomponents,thingsalongthoselines.
Jim
Sayyouhadavoidnearthetoeofasolderfilletandthespecsaysthatyouneedtohavelessthan75percentcoverage.Soyoulookatthecoverageandifavoidwasbiggerthan25percent,thatwouldreduceyourtotaltolessthan75percent.
Phil
Thetrickistodetermineifvoidsareasymptomoradefect,particularlybeforeyougoaboutdoinganyactualreworkingandmanipulationwhereyoucoulddomoreharmthangood.
Jim
Thatinitialspec,5.2.2,definesallvoids,blowholes,andpinholesasaprocessindicator.Soifyou’reseeingthem,they’retellingyouthatmaybethere’ssomethingwrong.Whetheraspecificonecausesyoutorejectapartorreworkitisoftenajudgmentcallagainstthecriteriain8.2.2.
Forvoidpass/failcriteriaforSMDcomponents(exceptforareaarraydefinedinIPC610E8.3.12),youcanrefertotheinformationbelow:
Phil
WelcometoBoardTalk.WearetheAssemblyBrothers,PhilZarrowandJimHallofITMConsulting,we’reheretoansweryourquestionsonSMTprocesses,equipment,materials,andprocedures.Whatisinourmailbagtoday,Jim?
Jim
TodaywehearfromHM.”IknowaboutvoidsinBGAsolderjoints,butisthereaqualitycriteriaforthesoldervoidsinpassivecomponents,includingresistors,capacitors,etc.?”
Whenitcomestospecifications,wealwaysrefertoIPC610.Andtheanswerisyes.InIPC610DinSection5.2.2calledSolderAnomaliesittalksaboutpinholesandblowholes,butalsoaddressesvoids.IfdefinesadefectforClassIIandClassIIIproductsaspinholes,blowholes,orvoidswhichreducetheconnectionbelowtheminimumrequirements.
Therequirementsforchipcomponents,resistorsandcapacitorsisgiveninIPC610DinSection8.2.2.Therearemanydifferentcategories,buttheytalkbasicallyaboutcoverageonthepadsandontheterminationsandanumberofthemgivepercentages.Sotheoretically,accordingtoIPC,youcouldmeasurethevoid.Ifit’saninternalvoidyou’llneedtouseanx-raymachine.Ifit’sanexternalvoidsuchasablowhole,youcouldjustmeasureitwithamicroscope.Andthenyoucouldapplythattothejointcategorysuchas50percentcoverage,75percentcoverage,andsoforththatarelistedinthe8.2.2sections.Thesemeasurementsaretheoreticallypossible,buttheyaretypicallyjudgmentcalls.
Phil
Whenwelookatthesespecs,we’rebasicallycomparingcontractareavoidswiththingslikemisalignments,skewedcomponents,thingsalongthoselines.
Jim
Sayyouhadavoidnearthetoeofasolderfilletandthespecsaysthatyouneedtohavelessthan75percentcoverage.Soyoulookatthecoverageandifavoidwasbiggerthan25percent,thatwouldreduceyourtotaltolessthan75percent.
That’seasytosayherequotingnumbersoffthetopofourheads,butIthinkinreallife,it’ssubjective.Buttoansweryourquestion,yes,therearecriteriaandtheyaredefinedintheIPC.
Phil
Thetrickistodetermineifvoidsareasymptomoradefect,particularlybeforeyougoaboutdoinganyactualreworkingandmanipulationwhereyoucoulddomoreharmthangood.
Jim
Thatinitialspec,5.2.2,definesallvoids,blowholes,andpinholesasaprocessindicator.Soifyou’reseeingthem,they’retellingyouthatmaybethere’ssomethingwrong.Whetheraspecificonecausesyoutorejectapartorreworkitisoftenajudgmentcallagainstthecriteriain8.2.2.
仅有底部端子焊料空洞—-因为对焊料高度没有要求,空洞不会影响最小焊接宽度要求,应该是可以允收的。