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ELEC 6740 Electronics ELEC 6740 Electronics ManufacturingManufacturingChapter 5: Surface Chapter 5: Surface Mount Design Mount Design ConsiderationsConsiderations
R. Wayne JohnsonR. Wayne JohnsonAlumni ProfessorAlumni Professor
OutlineOutlineOutlineOutlineOutlineOutlineOutlineOutline
System Design IssuesSystem Design IssuesPackage DriversPackage DriversReal Estate ConsiderationsReal Estate ConsiderationsManufacturing ConsiderationsManufacturing ConsiderationsCost ConsiderationsCost ConsiderationsThermal ConsiderationsThermal ConsiderationsPackage Reliability ConsiderationsPackage Reliability ConsiderationsSolder Joint Reliability ConsiderationsSolder Joint Reliability ConsiderationsInterconnect ConsiderationsInterconnect ConsiderationsCAD Layout ConsiderationsCAD Layout Considerations
System DesignSystem DesignSystem DesignSystem DesignSystem DesignSystem DesignSystem DesignSystem Design
Form, fit and functionForm, fit and functionFormForm
Relates to the physical size, shape, and weight of the Relates to the physical size, shape, and weight of the productproduct
Factor constraints: MULTIBUS I, MULTIBUS II, PC BUSFactor constraints: MULTIBUS I, MULTIBUS II, PC BUSSlot Slot spacingsspacings, connectors, etc., connectors, etc.
FitFitRelationship with other functions or products within Relationship with other functions or products within the systemthe system
FunctionFunctionProducts basic mission in lifeProducts basic mission in life
System DesignSystem DesignSystem DesignSystem DesignSystem DesignSystem DesignSystem DesignSystem Design
Application environmentApplication environmentCost constraintsCost constraints
Package DriversPackage DriversPackage DriversPackage DriversPackage DriversPackage DriversPackage DriversPackage Drivers
Cheap! PackagesThin and small outline packagesFor notebooks & chipset applications
Entry LevelCost Driven
Low cost plasticQFPs, TSOP,
BGA
Mid-RangeCost/PerformanceDriven
High performance & Lower cost packagesSMT Technology, CheaperAssembly cost to OEM
High EndPerformanceDriven
HighElectrical
& ThermalPerformance
Thermally enhancedPlastic packages
SMT, CPGA, PQFP,PPGA, BGA
Package RequirementsNarrow pad pitchesDecoupling capacitors
PGA, BGA, Flip Chip, MCM
Microprocessor I/OMicroprocessor I/OMicroprocessor I/OMicroprocessor I/OMicroprocessor I/OMicroprocessor I/OMicroprocessor I/OMicroprocessor I/O
Package DriversPackage DriversPackage DriversPackage DriversPackage DriversPackage DriversPackage DriversPackage DriversCostCost
Cost per I/OCost per I/OThermalThermal
Plastic vs. CeramicPlastic vs. CeramicHeat sinks, slugsHeat sinks, slugs
ElectricalElectricalParasiticsParasiticsPropagation delayPropagation delaySignal distortionSignal distortionElectrical noiseElectrical noise
Real EstateReal EstatePerimeter vs. area arrayPerimeter vs. area array
PGAPGAPGAPGAPGAPGAPGAPGA
Area arrayArea arrayThrough holeThrough holeRobust leadsRobust leadsSocketsSocketsKnown reliabilityKnown reliability
Fine Pitch PackagesFine Pitch PackagesFine Pitch PackagesFine Pitch PackagesFine Pitch PackagesFine Pitch PackagesFine Pitch PackagesFine Pitch Packages
QFPQFPReal estateReal estateLower cost Lower cost vs vs PGAPGA22--4 watts with heat slug4 watts with heat slug
BGABGABGABGABGABGABGABGA
Area array Area array –– real estatereal estateRobust manufacturing processRobust manufacturing processNo repair, only reworkNo repair, only reworkInspection, XInspection, X--ray onlyray only
Real EstateReal EstateReal EstateReal EstateReal EstateReal EstateReal EstateReal Estate
2.00x 2.00x –– 4.6x4.6xType I SMTType I SMT
1.20x 1.20x –– 1.40x1.40xType II SMTType II SMT
1.05x 1.05x –– 1.10x1.10xType III SMTType III SMT
Functional Density Functional Density IncreaseIncrease
Type of SMT Type of SMT AssemblyAssembly
Real EstateReal EstateReal EstateReal EstateReal EstateReal EstateReal EstateReal Estate
A = real estate area requirementA = real estate area requirementaa11, a, a22, , ………… = land pattern areas of different = land pattern areas of different componentscomponentsII11, I, I22, , ………… = = interpackage interpackage spacing requirementsspacing requirementsnn11, n, n22, , ………… = total number of each component= total number of each componentK = packing efficiency constant K = packing efficiency constant
1.10 for memory board1.10 for memory board1.30 for logic board1.30 for logic board
M = reserved area required for miscellaneous M = reserved area required for miscellaneous purposes such as clearance for edge card guide, purposes such as clearance for edge card guide, automated test assess, etc. automated test assess, etc.
A = {(aA = {(a11+ I+ I11)n)n11+(a+(a22+ I+ I22)n)n22+(a+(a33+ I+ I33)n)n33+ + …………} K+M} K+M
Land pattern/package Land pattern/package Land pattern/package Land pattern/package Land pattern/package Land pattern/package Land pattern/package Land pattern/package and and and and and and and and interpackage interpackage interpackage interpackage interpackage interpackage interpackage interpackage spacingspacingspacingspacingspacingspacingspacingspacing
Land pattern/package andLand pattern/package andLand pattern/package andLand pattern/package andLand pattern/package andLand pattern/package andLand pattern/package andLand pattern/package andinterpackageinterpackageinterpackageinterpackageinterpackageinterpackageinterpackageinterpackage spacingspacingspacingspacingspacingspacingspacingspacing
ManufacturingManufacturingManufacturingManufacturingManufacturingManufacturingManufacturingManufacturing
Ease of manufacturingEase of manufacturingInspection, test, repairInspection, test, repair
Manufacturing capabilityManufacturing capabilityComponent compatibility with Component compatibility with assembly processassembly process
PWB CostPWB CostPWB CostPWB CostPWB CostPWB CostPWB CostPWB Cost
PWB CostPWB CostPWB CostPWB CostPWB CostPWB CostPWB CostPWB Cost
110044442020
1100252525254040
2211252530305050
2222303030306060
5/55/56/66/6Pad Pad DiaDia..Ball Ball DiaDia..PitchPitch(mil)(mil)
Blind & Buried Blind & Buried Blind & Buried Blind & Buried Blind & Buried Blind & Buried Blind & Buried Blind & Buried ViasViasViasViasViasViasViasVias
PWB CostPWB CostPWB CostPWB CostPWB CostPWB CostPWB CostPWB Cost
Board Area & Layer Board Area & Layer Board Area & Layer Board Area & Layer Board Area & Layer Board Area & Layer Board Area & Layer Board Area & Layer CountCountCountCountCountCountCountCount
PWB Hole CostsPWB Hole CostsPWB Hole CostsPWB Hole CostsPWB Hole CostsPWB Hole CostsPWB Hole CostsPWB Hole Costs
Component CostComponent CostComponent CostComponent CostComponent CostComponent CostComponent CostComponent Cost
CSP more expensiveCSP more expensivePGAs PGAs more expensivemore expensiveCeramic more expensiveCeramic more expensive
Assembly CostAssembly CostAssembly CostAssembly CostAssembly CostAssembly CostAssembly CostAssembly Cost
30%30%Type I SMTType I SMT
19%19%Type II SMTType II SMT
00Type III SMTType III SMT
00Through HoleThrough Hole
Savings in Placement Savings in Placement CostCost
Type of AssemblyType of Assembly
Thermal DesignThermal DesignThermal DesignThermal DesignThermal DesignThermal DesignThermal DesignThermal Design
TTjj = junction temperature (= junction temperature (ooCC))ΘΘΘΘΘΘΘΘjaja = thermal resistance, junction to ambient (= thermal resistance, junction to ambient (ooCC/W)/W)PPdd = power dissipation at = power dissipation at TTjj (W)(W)TTa = ambient temperature
TTjj = (= (ΘΘΘΘΘΘΘΘjaja x Px Pdd) +T) +Ta
Thermal DesignThermal DesignThermal DesignThermal DesignThermal DesignThermal DesignThermal DesignThermal Design
Ceramic PackagesCeramic PackagesCeramic PackagesCeramic PackagesCeramic PackagesCeramic PackagesCeramic PackagesCeramic Packages
Thermal PerformanceThermal PerformanceThermal PerformanceThermal PerformanceThermal PerformanceThermal PerformanceThermal PerformanceThermal Performance
Air FlowAir FlowAir FlowAir FlowAir FlowAir FlowAir FlowAir Flow
Thermal Resistance (Thermal Resistance (Thermal Resistance (Thermal Resistance (Thermal Resistance (Thermal Resistance (Thermal Resistance (Thermal Resistance (ΘΘΘΘΘΘΘΘjajajajajajajaja))))))))
7272CopperCopperPLCC 20 pinPLCC 20 pin
9797CopperCopperSOIC 20 pinSOIC 20 pin
6868KovarKovarDIP 20 pinDIP 20 pin
Thermal Thermal Resistance (Resistance (ooCC/W)/W)
Lead Frame Lead Frame MaterialMaterial
Type of Type of PackagePackage
Max Power RatingMax Power RatingMax Power RatingMax Power RatingMax Power RatingMax Power RatingMax Power RatingMax Power Rating
Package ReliabilityPackage ReliabilityPackage ReliabilityPackage ReliabilityPackage ReliabilityPackage ReliabilityPackage ReliabilityPackage Reliability
IPC IPC –– Electronics trade associationElectronics trade associationwww.ipc.orgwww.ipc.org
EIA EIA –– Electronic Industries Electronic Industries AssociationAssociation
www.eia.orgwww.eia.orgJEDEC JEDEC –– Joint Electron Device Joint Electron Device Engineering CouncilEngineering Council
www.www.jedecjedec.org.org
Package Cracking Package Cracking Package Cracking Package Cracking Package Cracking Package Cracking Package Cracking Package Cracking During During During During During During During During Reflow Reflow Reflow Reflow Reflow Reflow Reflow Reflow AssemblyAssemblyAssemblyAssemblyAssemblyAssemblyAssemblyAssembly
Ratio of paddle size to minimum plastic thicknessRatio of paddle size to minimum plastic thicknessQuantity and distribution of moisture absorbed Quantity and distribution of moisture absorbed by the package prior to surface mountingby the package prior to surface mountingMaximum package temperature during solder Maximum package temperature during solder reflowreflow/rework/reworkAdhesion of molding compound to die, lead Adhesion of molding compound to die, lead frame, and other internal elementsframe, and other internal elementsMold or potting compound material propertiesMold or potting compound material propertiesCTE mismatch between different materials used CTE mismatch between different materials used in the packagein the packageComponent assembly mold processComponent assembly mold processDie Fabrication and wire bonding process Die Fabrication and wire bonding process ((cratering cratering only)only)
Pop CorningPop CorningPop CorningPop CorningPop CorningPop CorningPop CorningPop Corning
During During During During During During During During ReflowReflowReflowReflowReflowReflowReflowReflow
Moisture AbsorptionMoisture AbsorptionMoisture AbsorptionMoisture AbsorptionMoisture AbsorptionMoisture AbsorptionMoisture AbsorptionMoisture Absorption
Moisture Absorption & Moisture Absorption & Moisture Absorption & Moisture Absorption & Moisture Absorption & Moisture Absorption & Moisture Absorption & Moisture Absorption & DesorptionDesorptionDesorptionDesorptionDesorptionDesorptionDesorptionDesorption
JEDEC Classification JEDEC Classification JEDEC Classification JEDEC Classification JEDEC Classification JEDEC Classification JEDEC Classification JEDEC Classification
JEDEC Moisture JEDEC Moisture JEDEC Moisture JEDEC Moisture JEDEC Moisture JEDEC Moisture JEDEC Moisture JEDEC Moisture SensitivitySensitivitySensitivitySensitivitySensitivitySensitivitySensitivitySensitivity
Level Floor Life SoakConditions Time Time (hrs) Conditions
1 <30oC85%RH
Unlimited 168 85oC85%RH
2 <30oC60%RH
1 year 168 85oC60%RH
2a <30oC60%RH
4 weeks 696 30oC60%RH
3 <30oC60%RH
168hrs 192 30oC60%RH
Joint IPC/JEDEC Standard J-STD-020A
JEDEC Moisture JEDEC Moisture JEDEC Moisture JEDEC Moisture JEDEC Moisture JEDEC Moisture JEDEC Moisture JEDEC Moisture SensitivitySensitivitySensitivitySensitivitySensitivitySensitivitySensitivitySensitivity
Following soak, parts are subjected Following soak, parts are subjected to 3 reflow cyclesto 3 reflow cyclesIssueIssue
Eutectic Eutectic SnSn//Pb Pb or Lead Freeor Lead FreeInspected:Inspected:
ElectricalElectricalVisual for cracksVisual for cracksAcoustic microscopy for Acoustic microscopy for delaminationdelamination
InspectionInspectionInspectionInspectionInspectionInspectionInspectionInspection
Cracks are not allowed to intersect the Cracks are not allowed to intersect the wire bond, ball bond, or wedge bond.wire bond, ball bond, or wedge bond.Cracks are not allowed to extend from any Cracks are not allowed to extend from any lead finger to any other internal feature lead finger to any other internal feature (lead finger, chip, die attach paddle).(lead finger, chip, die attach paddle).Cracks are not allowed to extend more Cracks are not allowed to extend more than 2/3 the distance from any internal than 2/3 the distance from any internal feature to the outside package feature to the outside package
Packages & Humidity & Packages & Humidity & Packages & Humidity & Packages & Humidity & Packages & Humidity & Packages & Humidity & Packages & Humidity & Packages & Humidity & TemperatureTemperatureTemperatureTemperatureTemperatureTemperatureTemperatureTemperature
Packages & Humidity & Packages & Humidity & Packages & Humidity & Packages & Humidity & Packages & Humidity & Packages & Humidity & Packages & Humidity & Packages & Humidity & TemperatureTemperatureTemperatureTemperatureTemperatureTemperatureTemperatureTemperature
Plastic Thickness & Die Plastic Thickness & Die Plastic Thickness & Die Plastic Thickness & Die Plastic Thickness & Die Plastic Thickness & Die Plastic Thickness & Die Plastic Thickness & Die Attach Pad AreaAttach Pad AreaAttach Pad AreaAttach Pad AreaAttach Pad AreaAttach Pad AreaAttach Pad AreaAttach Pad Area
HandlingHandlingHandlingHandlingHandlingHandlingHandlingHandling
Shipped in ‘Dry Bags’Shipped in ‘Dry Bags’Desiccant materialsDesiccant materialsHumidity indicator cardHumidity indicator card6 month shelf6 month shelf--life if life if unopenedunopened
PackagingPackagingPackagingPackagingPackagingPackagingPackagingPackaging
Bake OutBake OutBake OutBake OutBake OutBake OutBake OutBake Out
Bake OutBake OutBake OutBake OutBake OutBake OutBake OutBake Out
TemperatureTemperature125 (125 (++5) 5) ooCC
Duration Duration 2424--25 hours25 hours
Chamber RHChamber RH<50%<50%
Limited reLimited re--bakebake1515--2020µµµµµµµµin Cuin Cu--Sn Sn intermetallicintermetallic
TemperatureTemperature40 (+5, 40 (+5, --0) 0) ooCC
Duration Duration 192 hours (min.)192 hours (min.)
Chamber RHChamber RH<5%<5%
Unlimited reUnlimited re--bakebake
Solder Joint ReliabilitySolder Joint ReliabilitySolder Joint ReliabilitySolder Joint ReliabilitySolder Joint ReliabilitySolder Joint ReliabilitySolder Joint ReliabilitySolder Joint Reliability
Solder Joint FailureSolder Joint FailureCTE mismatch between PWB and CTE mismatch between PWB and componentcomponentCompliance of leadCompliance of lead
CorrosionCorrosion
Solder Joint ReliabilitySolder Joint ReliabilitySolder Joint ReliabilitySolder Joint ReliabilitySolder Joint ReliabilitySolder Joint ReliabilitySolder Joint ReliabilitySolder Joint Reliability
1.3 million1.3 million580,000580,000210,000210,000Total Solder Joint Total Solder Joint CyclesCycles
PassPassPassPassPassPassLife TestLife Test
PassPassPassPassPassPassTemperature Cycling Temperature Cycling (non(non--operating)operating)
PassPassPassPassN/aN/aTemperature Cycling Temperature Cycling (operating)(operating)
PassPassPassPassPassPassHumiodity Humiodity StorageStorage
PassPassPassPassN/AN/AMechanical ShockMechanical Shock
PassPassPassPassPassPassRandom VibrationRandom Vibration
Type IIType IIType IType IType IIIType III
Environmental Test Environmental Test Environmental Test Environmental Test Environmental Test Environmental Test Environmental Test Environmental Test ConditionsConditionsConditionsConditionsConditionsConditionsConditionsConditions
Random VibrationRandom Vibration0.01g0.01g22/Hz sloping to 0.01g/Hz sloping to 0.01g22/Hz from 20Hz to 1kHz/Hz from 20Hz to 1kHz
Mechanical ShockMechanical Shock50g sine for 11ms50g sine for 11ms
Humidity StorageHumidity Storage5 days at 555 days at 55ooC, 95%RHC, 95%RH
Temperature Cycling (operational)Temperature Cycling (operational)--15 to 7015 to 70ooC for 5 daysC for 5 days
Temperature Cycling (nonTemperature Cycling (non--operational)operational)--40 to 12540 to 125ooC; 2500 cyclesC; 2500 cycles
Life TestLife Test3000 hours at 603000 hours at 60ooCC
Environmental Test Environmental Test Environmental Test Environmental Test Environmental Test Environmental Test Environmental Test Environmental Test ConditionsConditionsConditionsConditionsConditionsConditionsConditionsConditions
www.www.jedecjedec.org.org
Thermal Cycling & Thermal Cycling & Thermal Cycling & Thermal Cycling & Thermal Cycling & Thermal Cycling & Thermal Cycling & Thermal Cycling & Thermal ShockThermal ShockThermal ShockThermal ShockThermal ShockThermal ShockThermal ShockThermal Shock
Dwell times and ramp rates are importantDwell times and ramp rates are importantFatigue: cycling strain loadingFatigue: cycling strain loadingCreep: constant stress loadingCreep: constant stress loadingSolder joint failure includes both fatigue Solder joint failure includes both fatigue and creepand creep
The degree of each is a function of the cycle The degree of each is a function of the cycle conditionsconditions
Cycles to failure in the field are always Cycles to failure in the field are always less than in laboratory testsless than in laboratory tests
Less hold time at Less hold time at hign hign temperaturetemperatureLess stress relaxationLess stress relaxation
Stress Strain Stress Strain Stress Strain Stress Strain Stress Strain Stress Strain Stress Strain Stress Strain –––––––– No Dwell No Dwell No Dwell No Dwell No Dwell No Dwell No Dwell No Dwell TimeTimeTimeTimeTimeTimeTimeTime
Stress Strain Stress Strain Stress Strain Stress Strain Stress Strain Stress Strain Stress Strain Stress Strain –––––––– Complete Complete Complete Complete Complete Complete Complete Complete Stress RelaxationStress RelaxationStress RelaxationStress RelaxationStress RelaxationStress RelaxationStress RelaxationStress Relaxation
Number of Cycles to Number of Cycles to Number of Cycles to Number of Cycles to Number of Cycles to Number of Cycles to Number of Cycles to Number of Cycles to FailureFailureFailureFailureFailureFailureFailureFailure
The area of the The area of the hysteresis hysteresis loop is a loop is a measure of the fatigue damage per measure of the fatigue damage per cyclecycleCyclic fatigue damage is cumulativeCyclic fatigue damage is cumulativeThe larger the The larger the hysteresis hysteresis loop, the loop, the fewer cycles to failurefewer cycles to failure
Thermal Cycle ProfileThermal Cycle ProfileThermal Cycle ProfileThermal Cycle ProfileThermal Cycle ProfileThermal Cycle ProfileThermal Cycle ProfileThermal Cycle Profile
Interconnect Interconnect Interconnect Interconnect Interconnect Interconnect Interconnect Interconnect
Connection to Power and Ground Connection to Power and Ground PlanesPlanesPropagation DelayPropagation DelayCrossCross--talktalk
Line width and spacingLine width and spacingLine lengthLine lengthDielectric constantDielectric constantDistance from ground planeDistance from ground plane
Cross TalkCross TalkCross TalkCross TalkCross TalkCross TalkCross TalkCross Talk
CADCADCADCADCADCADCADCAD
Parts libraryParts libraryAutomated layoutAutomated layoutDesign rule checkingDesign rule checking
