表面贴装片式元器件-仅有底部端子焊料空洞可接受标准?

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。