IPC-2223E

2020-January

SectionalDesignStandardforFlexible/Rigid-Flexible

PrintedBoards

SupersedesIPC-2223DSeptember2016

AninternationalstandarddevelopedbyIPC

AssociationConnectingElectronicsIndustries

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CopyrightAssociationConnectingElectronicsIndustriesProvidedbyIHSMarkitunderlicensewithIPC

NoreproductionornetworkingpermittedwithoutlicensefromIHS

NotforResale,02/04/202002:05:17MST

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IPC-2223E

SectionalDesignStandardforFlexible/Rigid-FlexiblePrintedBoards

DevelopedbytheFlexibleCircuitsDesignSubcommittee(D-11)oftheFlexibleCircuitsCommittee(D-10)ofIPC

Supersedes:

IPC-2223D-September2016IPC-2223C-November2011IPC-2223B-May2008

IPC-2223A-June2004

IPC-2223-November1998IPC-D-249-January1987

Usersofthispublicationareencouragedtoparticipateinthedevelopmentoffuturerevisions.

Contact:

IPC

January2020 IPC-2223E

TableofContents

SCOPE 1

Purpose 1

ClassificationofProducts 1

PrintedBoardType 1

InstallationUses 4

RevisionLevelChanges 4

APPLICABLEDOCUMENTS 4

IPC 4

JointIndustryStandards 4

GENERALREQUIREMENTS 5

DesignModeling 5

DesignLayout 5

MechanicalLayoutEfficiency(ConsiderFinalPanelization) 5

FabricationDrawingRecommendations 5

Schematic 5

TestRequirementConsiderations 6

Environmental 6

Mechanical/Flexural 6

MATERIALS 6

MaterialSelection 6

MaterialOptions 7

DielectricMaterials(IncludingPrepregandAdhesives) 7

PreimpregnatedBondingMaterial(Prepreg) 7

Adhesives(Liquid) 7

FlexibleAdhesiveBondingFilms(Cast

AdhesiveorBondply) 7

ConductiveAnisotropicAdhesives 7

CoverMaterials 8

ConductiveMaterials(SurfaceFinishes) 9

ElectrolyticCopperPlating 9

NickelPlating 10

Tin-LeadPlating 10

SolderCoating 10

OtherMetallicCoatings 11

ElectronicComponentMaterials(Buried

ResistorsandCapacitors) 11

ConductiveCoatingsforShielding 11

OrganicProtectiveCoatings 11

SolderMask 11

ConformalCoating 11

MarkingandLegend 11

MECHANICALANDPHYSICALPROPERTIES 11

FabricationRequirements 11

BarePrintedBoardFabrication 11

RolltoRollFabrication 11

Product/PrintedBoardConfiguration 12

CircuitProfile(Outline) 12

RigidAreaConsiderations 13

FlexibleAreas 13

PreformingBend 16

DifferentialLengths 17

Shielding 21

Ground/PowerPlane 21

StiffenersandHeatSinks 21

StrainReliefFilletGuidelinesforFlexible

andRigid-FlexPrintedBoards 21

AssemblyRequirements 22

MechanicalConsiderations 22

ArraySub-PalletsforFlexibleandRigid

PrintedBoards 22

SinglePartSub-Pallets 22

Non-PalletizedFlexibleandRigid-Flex

PrintedBoards 22

Moisture 23

InfraredPreheatsandReflow 23

AdhesiveTg 23

Dimensioning 23

DatumFeatures 23

ELECTRICALPROPERTIES 23

ElectricalConsiderations 23

ImpedanceandCapacitanceControl 24

ImpedanceModelingSoftware 24

MaterialThicknessandStackUp 24

ConductorPitch 24

NarrowConductors 24

DifferentialImpedance 25

UnbondedFlexibleImpedanceControlled

Layers(‘‘Loose-leaflayers’’) 25

ModificationstoShieldLayers 26

DielectricConstantChangesOverFrequency 27

THERMALMANAGEMENT 27

COMPONENTANDASSEMBLYISSUES 27

GeneralPlacementRequirements 27

StandardSurfaceMountRequirements 27

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IPC-2223E January2020

LandsforSurfaceMounting 27

ConstraintsonMountingtoFlexibleSections 27

InterfacialConnections 27

OffsetLands 27

HOLES/INTERCONNECTIONS 28

GeneralRequirementsforLandswithHoles 28

LandRequirements 28

AnnularRingRequirements 28

EyeletorStandoffLandAreaConsiderations 28

LandSizeforNon-PlatedComponentHoles 28

LandSizeforPlated-ThroughComponent

Holes 28

ThermalReliefinConductorPlanes 28

SurfaceMountComponents 28

NonfunctionalLands 28

Land-to-ConductorTransition 29

UnsupportedEdgeConductors/Fingers 29

Holes 36

Unsupported(Non-Plated)ComponentHoles 36

PlatedComponentHoles 36

CopperFilledVias 36

Back-drilledHoles 36

CoverlayAccessOpenings 36

CoverlayAccess,UnsupportedLands 36

CoverlayAccess,Holes 37

CoverlayAccessSpacing 38

LandAccess/ExposedLands 38

Type1LandAccess,OppositeSides 38

CONDUCTORS 38

ConductorCharacteristics 38

ConductorRouting 38

ConductorEdgeSpacing 39

LandCharacteristics 39

LargeConductiveAreas 39

DOCUMENTATION 39

QUALITYASSURANCE 39

APPENDIXA DesignTutorial 40

Figures

Figure1-1 Type1Single-SidedFlexiblePrintedBoard–AdhesiveSubstrateConstruction 1

Figure1-2 Type1Single-SidedFlexiblePrintedBoard–AdhesivelessSubstrateConstruction 1

Figure1-3 Type2Double-SidedFlexiblePrintedBoard–AdhesiveSubstrateConstruction 2

Figure1-4 Type2Double-SidedFlexiblePrintedBoard–AdhesivelessSubstrateConstruction 2

Figure1-5 Type3MultilayerFlexiblePrintedBoard–AdhesiveSubstrateConstruction 2

Figure1-6 Type3MultilayerFlexiblePrintedBoard–AdhesivelessSubstrateConstruction 2

Figure1-7 Type4Rigid-FlexPrintedBoard–

AdhesiveSubstrateConstruction 3

Figure1-8 Type4Rigid-FlexPrintedBoard–

AdhesivelessSubstrateConstruction 3

Figure1-9 Type5FlexibleorRigid-FlexPrintedBoardwithoutPTHs–AdhesiveSubstrate

Construction 3

Figure1-10Type5FlexibleorRigid-FlexPrintedBoardwithoutPTHs–AdhesivelessSubstrateConstruction 3

Figure3-1 DimensionalModeling 5

Figure3-2 FinalPanelization 5

Figure4-1 FlexibleCross-SectionalConstruction

Examples 6

Figure4-2 UnbondedFlexCross-Sectional

ConstructionofRigidFlex 6

Figure4-3 PlatingforAdhesivelessSubstrate

Applications 10

Figure4-4 SelectivePlatingforAdhesiveSubstrateApplications 10

Figure5-1 CircuitsNestedOnaPanel 12

Figure5-2 SpecialFlexiblePrintedBoardFeatures 12

Figure5-3 CutoutwithaDrilledHole 12

Figure5-4 ReinforcementPatchforFlexArea 12

Figure5-5 SlitsandSlots 13

Figure5-6 SpacingofPTHfromRigidtoFlex

Interface 13

Figure5-7 ReducedBendRadii 14

Figure5-8 ConductorsinBendAreas 14

Figure5-9 Bend/CreaseAreasCenterLines 15

Figure5-10NeutralAxisIdealConstruction 15

Figure5-11DefinitionofBendRatio 16

Figure5-12IrregularFolds 17

Figure5-13DifferentialPrintedBoardLengths 18

Figure5-14DifferentialPrintedBoardLengths,

Rigid-Flex 18

Figure5-15Bookbinder 20

Figure5-16StaggeredFlexibleLayerBands 20

Figure5-17StaggeredFlexibleLayerBands 20

Figure5-18TypicalExampleofCopperRemovalfor

FlexibleShielding 21

Figure5-19StiffenerThicknessPreferredinOrderto

ApplyStrainReliefFillet 21

Figure5-20StrainRelief 22

Figure5-21RigidRailsforSinglePartSub-Pallets 22

Figure5-22EstablishingDatums 23

Figure6-1 AdjustmenttoDielectricThicknessbetween

RigidandFlexibleRegions 24

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January2020 IPC-2223E

Figure6-2 ConductorPitchforDifferentialPairs 25

Figure6-3 TDRWaveformforType2Flexible

PrintedBoard 25

Figure6-4 BucklingofUnbondedFlexibleLayers 26

Figure6-5 CrossHatching 26

Figure9-1 ConductortoLandTransitions 28

Figure9-2 Sculptured,Straight,TaperedFingers 30

Figure9-3 Sculptured,FormedforSurfaceMount 30

Figure9-4 Sculptured,FormedforThrough-Hole 30

Figure9-5 StraightFingersforLapSolderingtoPrintedBoard 30

Figure9-6 AdhesiveSqueezeOutWhereFingersExitInsulation 33

Figure9-7 LaserAblatedWindow 33

Figure9-8 BrokenFingersResultingfromPoor

Handling 33

Figure9-9 FingersConnectedwithaFoilBussBar 34

Figure9-10InsulatorBussBarwithNotchedFingers 34

Figure9-11FingersAttachedtoaSupportBar 34

Figure9-12StaggeredBase/CoverlayEdgesUsedtoReduceStressPoints 34

Figure9-13SculpturedFlexShowingtheFoilThicknessTransition 35

Figure9-14FingersBrazedtoCircuitLands 35

Figure9-15BondingofUnsupportedFingerstoPrintedBoardwithReinforcement 35

Figure9-16CoverlayAccessOpeningsandExposedUnsupportedLands 37

Figure9-17CoverlayAccessOpeningforUnsupportedLands 37

Figure9-18CoverlayAccessOpeningsandExposedSupportedLands 38

Figure10-1ConductorRouting,Rigid-FlexTransition 38

FigureA-1 SingleRowZIFStylePrintedBoardContactArea 41

FigureA-2 DualRowZIFStylePrintedBoard

ContactArea 41

Tables

Table4-1 CharacteristicsofTypicalFlexibleDielectrics 8

Table4-2 MinimumAverageCopperThickness,mm[in] 9

Table9-1 MinimumStandardFabricationAllowanceforInterconnectionLands,mm[in] 28

Table9-2 NonfunctionalLandConsiderations 29

Table9-3 TypicalFoilOptionsforDesigningforFlex

CircuitswithUnsupportedFingers 31

Table9-3 TypicalFoilOptionsforDesigningforFlexCircuitswithUnsupportedFingers

(continued) 32

Table9-4 CommonBrazedFingerOptions 35

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January2020 IPC-2223E

SectionalDesignStandardforFlexible/Rigid-FlexiblePrintedBoards

SCOPE

Thisstandardestablishesthespecificrequirementsforthedesignofflexibleandrigid-flexibleprintedboardapplicationsanditsformsofcomponentmountingandinterconnectingstructures.Theflexiblematerialsusedinthestructuresarecomprisedofinsulatingfilms,reinforcedand/ornon-reinforced,dielectricincombinationwithmetallicmaterials.Theseinterconnectingboardsmaycontainsingle,double,multilayer,ormultipleconductivelayersandcanbecomprisedwhollyofflexoracom-binationofbothflexandrigid.

PurposeTherequirementscontainedhereinareintendedtoestablishspecificdesigndetailsthatshallbeusedincon-junctio