Design Guidelines for Reliable Surface Mount Technology ...

1 IPC-D-279 Design Guidelines for ReliableSurface Mount TechnologyPrinted Board AssembliesIPC-D-279 July 1996 The Institute forInterconnectingand PackagingElectronic Circuits2215 Sanders RoadNorthbrook, Illinois60062-6135 TelFaxURL:847 of .. Philosophy .. the Design Team .. Reliability Requirements .. the Product Life the Product Organization .. for Reliability of SM Assemblies .. Materials and Coatings .. Processes and .. and for Interconnecting and PackagingElectronic Circuits (IPC) .. Industries Association .. Industry Standards .. FOR RELIABILITY FOR SURFACEMOUNT Cycle Environment.

2 Processes .. Temperature Excursions .. and Environmental Stress Screening(ESS) .. Temperature Swings .. Shock .. Shock and Vibration .. Resistance .. Compatibility .. Radiation .. Environment .. Board Design and Design and Layout .. Design and Conformal Coating .. Patterns .. About Neutral Axis .. Board Trace Widths and Spaces .. and PTV Thermal Isolation/Relief .. Pads .. Between Parts .. Pads-Only with Reduced Clearances(Traces Under) .. with Reduced Clearance andOpen of Thermal Expansion (CTE)and Joint Reliability .. Design Parameters.

3 Design Parameters .. Hole and Via Reliability .. of SM Solder Attachments .. of Insulation Resistance .. Substrate Categories .. and Their Functions: .. and its Effects on PolymerSubstrates .. of Thermal Expansion (CTE) ofPolymer Cores in Substrates .. Board Stiffness and Printed Board with MetalSupport Plane .. Wire Structures with Metal SupportPlane .. of Polymer Substrates .. Process Effects on PolymerSubstrates .. Board Solderability .. for Reliability of Plated-Through-HoleVias (PTVs).. COMPONENT Selection Strategy .. Leadframe and Local Materials.

4 20 July Lead Configuration Selection .. Wing Components .. Components .. Grid Pitch Surface Mount Components(PSMC) .. Termination Coplanarity Lead Configuration .. Termination Barrier and Tin-Lead Solder TerminationFinishes .. Recommendations When UsingElectrically Conductive , Palladium, Silver Termination Finishes .. of Termination Finishes .. Considerations .. Mismatch Packaging or Custom Devices Use Precaution .. to Avoid or to Use withCaution .. Selection Considerations forMilitary and Space Applications .. MASK AND CONFORMAL Mask Considerations for Mask Selection.

5 Mask Thickness Solder Mask and Coatings .. PROCESSES AND Design Paste Placement .. Paste Soldering .. for Manufacturability .. for Testability (DfT).. Books on SMT Process and Design .. Soldering Process Technical Solder Paste .. Cleaning .. Joint Reliability .. of Electronic Packages andPackaging .. , High Speed Transients and ElectricalOverstress .. Acoustic Microscopy .. Package Cracking .. Joint Metallurgy and Etching .. Thermal Design .. Fabrication Information .. Derating, Applications,Qualification .. , Manufacturability.

6 , Shock .. Life , Solderability, Soldered Mask and Conformal Coating .. Reliability .. 33 Appendix ADesign for Reliability (DfR) of Mount SOLDER MECHANISMS AND Joints and Attachment Types .. Expansion Mismatch .. Expansion Mismatch .. Expansion Attachment Failure .. PREDICTION Modeling .. 1 Solder Joint 2 Large TemperatureExcursions .. 3 High-Frequency/Low-Temperatures .. 4 Local Expansion Mismatch .. 5 Very Stiff Leads/Very LargeExpansion Mismatches .. 40 IPC-D-279 July Failure Distribution and FailureProbability .. Cyclic Load Histories.

7 Reliability Evaluation .. FACTORS FOR EMERGINGADVANCED Chip on Laminate .. Arrays (BGA, CGA).. Packages (TSOP) .. AND QUALIFICATION Joint NUMERICAL EXAMPLERELATING REQUIRED Design LIFE TOACCELERATED RELIABILITY 47 Appendix BDesign for Reliability (DfR) ofPlated-Through Via (PTV) VIA (PTV) Plating Copper Plating .. Copper Plating .. Mechanisms and Failure .. Quality .. Impact of Assembly Processes and ESSP rocedures .. Impact of Test Procedures and CyclicOperating Environments .. PREDICTION FACTORS FOR EMERGINGADVANCED AND QUALIFICATION 57 Appendix CDesign for Reliability (DfR) of RESISTANCE DAMAGEMECHANISMS AND Insulation Resistance (SIR).

8 Corrosion .. Growth .. Anodic Filaments (CAF).. RESISTANCE Resistance Degradation .. Anodic Filament Failure .. FACTORS FOR EMERGINGADVANCED AND QUALIFICATION Test Affecting SIR Readings 63 Appendix DThermal ANALYSIS AT THE Ambient Temperature of an ElectronicSystem (Ta) .. Temperature Rise of the Cooling Agentat the Device Level ( TCA).. Temperature Rise Inside the DeviceBoundary Layer ( TBL).. Temperature Rise Inside the DevicePackage ( TP) .. Wake ( TTW) .. THE SOLDER JOINTSTEMPERATURE OF ELECTRONIC .. Convection .. Forced Cooling.

9 Pipes .. Liquid Natural Convection Liquid Cooling .. Forced Liquid Cooling .. THERMAL 69 July Level Cooling .. Parts .. 69 Appendix EEnvironmental of Rework and Repair .. Transition Temperature for PrintedBoards .. Compound Transition Temperature for PlasticEncapsulating .. Vapor Pressure Effects on PlasticEncapsulated Components .. Vapor Pressure Effects on PrintedBoards .. Melt Temperature Excursion ( T) and TemperatureRate of Change ( T/ t).. Flexure .. Impact .. Discharge (ESD).. FAILURES/STRESS Derating Reference Conditions .. Most Important Stress and SomePrecautions.

10 Modes/Failure Mechanisms .. OF Stresses and Component Responseto OF TEMPERATURE AS ACOMPONENT STRESS Reversible/TemporaryChanges in Component Parameters .. Irreversible/PermanentChanges in Component Parameters .. of Low Temperature .. of Temperature Shock .. AND CURRENT (Electrostatic Discharge/Electrical Overstress).. AND GAS AND SUSCEPTIBILITY, RADIATION, ATMOSPHERICPRESSURE/HIGH 82 Appendix LEADLESS CHIP CARRIER(CLLCC).. ELECTRODE FACE BONDED(MELFs).. ABOVE SM PICK AND PLACE FEEDER WITH RUBBER SM COMPONENTS, MOISTURE,AND SM REFLOW and Resistive Shorts in PSMCs.