1、Section 9.3 Basic Au Wire Bond Process2022-10-5ContentspBasic IntroductionpGold Wire BonderpBonding SequencepMaterial&ToolspBond Quality2022-10-5Basic IntroductionpUnderstand an IC PackagepIC Manufacturing FlowpWire Bonding Introduction2022-10-5Cross-section of an IC PackageDieGold WireLead Frame202
2、2-10-5Wafer GrindingDie BondingWafer SawToaster Wire Bonding Die Surface Coating Molding Laser MarkSolder BallPlacement SingulationPackingIC Manufacturing FlowDejunk TrimSolder PlatingSolder PlatingForming/SingulationTrim/Forming BGASURFACEMOUNTPKGTHROUGHHOLE PKG2022-10-5Gold Wire Bonding2022-10-5We
3、dge Bonding2022-10-5What technique is used in Gold Wire Bonding?2022-10-5Wire Bonding TechniquespThere are three basic wire bonding techniques:n Thermosonic bonding:utilizes temperature,ultrasonic and low impact force,and ball/wedge methods.n Ultrasonic bonding:utilizes ultrasonic and low impact for
4、ce,and the wedge method only.n Thermocompression bonding:utilizes temperature and high impact force,and the wedge method only.2022-10-5Thermocompression vs ThermosonicpThermocompression welding usually requires interfacial temperature of the order of 300 C.This temperature can damage some die attach
5、 plastics,packaging materials,and laminates,as well as some sensitive chips.pThermosonic welding,the interface temperature can be much lower,typically between 100 to 150 C,which avoids such problems.The ultrasonic energy helps disperse contaminates during the early part of the bonding cycle and help
6、s complete the weld in combination with the thermal energy.2022-10-5Advantages of ThermosonicpMetallurgical joining is more reliable than conductive particles and adhesive joining.pProcess cycle time can be reduced from several minutes to less than 10 seconds.pLower manufacturing cost per unit.2022-
7、10-5WirebondingOperating TemperatureWire MaterialsPad MaterialsNoteThermo-compression300-500 CAuAl,AuHigh pressure,no ultrasonic energyUltrasonic25 CAu,AlAl,AuLow pressure in ultrasonic energyThermosonic100-240 CAu,CuAl,AuLow pressure in ultrasonic energyComparison of Different Wire Bonding Techniqu
8、es2022-10-5What are the important parameters in Gold Wire Bonding?2022-10-5Bonding ParameterspThermosonic Bonding n Pressure(Force)n Amplify&Frequency(Power 138KHz)n Welding Time(Bond Time)n Welding Temperature(Heater)High Power3.2W maxLow Power1.6W maxUltra-Low Power0.8W maxPower-mWVib.-umPower-mWV
9、ib.-umPower-mWVib.-um32003.2116002.268001.592022-10-5SiO2Si Bonding PrincipleAlPressure(Force)Vibration(Power)Al2O3GlassHeat2022-10-5Next to Gold Wire Bonder2022-10-5Gold Wire BonderpMachine RoadmappUnderstand Individual PartpMachine SpecificationpBonding Temperature2022-10-5ASM Gold Wire Bonder Roa
10、dmappMachine Model(ATS)n AB308AB309AB309AAB339AB339EagleEagle60 Eagle60AP Harrier Twin Eagle HummingBird n Eagle50?2022-10-5ASM Gold Wire Bonderp Machine Model(ATS)Description2022-10-5Matching1)Eagle60AP2)Eagle60-033)HummningBird4)Harrier5)Twin EagleA.B.C.D.E.ACEDB2022-10-5Eagle60AP Machine Introduc
11、tion2022-10-5Eagle60 vs Eagle60APEagle60Eagle60APFine pitch 35 m.30 m.Speed 60+ms.60 ms.BondheadDigital bondheadNew bondhead with 810%faster Bond Placement Accuracy 3 m 3 sigma 2.5 m 3 sigmaLoop TypesStandard looping databaseAdditional Escargot,Flex,Bell loopOpticsProgrammableBall Formation Monitori
12、ngStandard8x fasterCapacitance non-stick detectionStandard10 x faster2022-10-5uLow impact forceuReal time Bonding Force monitoringuHigh resolution z-axis position with 0.4 micron per encoder stepuFast contact detectionuSuppressed Force vibration&Fast Force responseuFast response voice coil wire clam
13、pBond Head ASSY2022-10-5X Y TableuLinear MotoruHigh power AC Current AmplifieruDSP based control platformuHigh X-Y positioning accuracy of+/-3 um3 sigmauResolution of 0.2 um per encoder step2022-10-5W/H ASSYpIndexing resolution of 1um per encoder steppFully programmable indexer&trackspMotorized wind
14、ow clamp with soft close featurepOutput indexer with leadframe jam protection featurepTool less conversion window clamps and top plate enables fast device2022-10-5Bonding SystemuBonding Method Thermosonic(TS)uBQM ModeMulti-mode with programmable BQM BduWire Size15.2um up to 76.2um(Au,Cu)uWire Length
15、0.6 to 8mmuBonding Accuracy+/-2.5um 3 sigmauBonding Area54mm X 65mm(LF Width 72mm)54mm X(137-LF Width)mmuBonding Speed+60ms for 2mm Wire(Q loop)uBond Force Range1400 gramuLoop TypeQ-Auto,Square&PentauLoop Height Range316 miluXY Resolution 0.2 umuZ Resolution0.4 umuFine Pitch Capability 30 um pitch 0
16、.6 mil wireuNo.of Bonding Wires up to 3000uProgram Storage1000 programs on Hard DiskuTransducer System138KHZ2022-10-5Vision Systemu Pattern Recognition Time60 ms/pointu Pattern Recognition Accuracy 0.37 umu Lead Locator Detection12 ms/lead u Minimum Lead Pitch80 umu Post Bond Inspection1st,2nd Bond
17、and Wire Tracingu Depth of Field3.5X(320um)8X(100um)Facilitiesu Single Phase 110 VAC(optional 100/120/200/210/220/230/240 VACu Floor Spacing 720mm(width)X 820mm(length)X 1600mm(height)2022-10-5Material Handling SystemuIndexer Resolution1umuLeadframe Position Accuracy 2 miluApplicable Leadframe W=23
18、90 mm bonding area in Y=65mm L =140 295 mm T =0.1 0.8 mmuApplicable Magazine W=16 100 mm(Maximum)L =140 295 mm H =180 mm(Maximum)uMagazine Pitch 2.4 10 mm(0.09”0.39“)uDevice Changeover 4 minutes(within same LF type)uPackage Changeover 1000,490/1004,8,1175%)2022-10-5Inter-metallic Layer ThicknessX=Kt
19、1/2Where X is the inter-metallic layer thickness,t is the time and K is the rate constant which is calculated by following:K=Ce-E/KT Where C is the rate constant,e is the activation energy,K is the Boltzman constant,and T is the temperature in absolute scale.2022-10-5CBall bondTest specimenSpecimen
20、clampShearing ramWireBond shoulderInterfacial contactball bond weld areaBonding padh(A)UnshearedCLCBall bondCLTest specimenSpecimen clampBonding padFull ball attached to wire-except for regionsof intermetallic voidingBall separated at bonding pad-Ball interface-residual intermetallic(and sometimes p
21、ortion of unalloyed ball and metal)on pad in bond interaction area(D)Ball bond-bonding pad interface separation(typical Au to Al)CTest specimenSpecimen clampShearing ramWireMinor fragment of ballattached to wireBonding padCLBall sheared too high(off line,etc.)only aportion of shoulder andball top re
22、movedInterfacial contactball bond weld area(B)Wire(ball top and/or side)shearCBall bondCLTest specimenSpecimen clampShearing ramBonding padMajor portion of ball attached to wireInterfacial contact-ball bond weld area intact(C)Below center line shear,ball sheared through(typically Au to Au)CBall bond
23、CLTest specimenSpecimen clampBonding padPad metallization separates fromunderlying surfaceResidual pad on ball ball-pad interfaceremains intact(E)Bond pad liftsTest specimenSpecimen clampCBall bondCLBonding padBonding pad lifts,taking portion of underlying substrate material with it(F)CrateringResid
24、ual pad and substrate attachedto ball,ball-pad interface remainsintactShear Failure Modes2022-10-5Normal Condition2022-10-5Material Problem2022-10-5With BallWirePad SizeMissing BallWire BrokenBonding Ball InspectionpBall Detection 2022-10-5Ball Size Pad CenterBall CenterBall Placement(X,Y)Ball Off P
25、ad Bonding Ball Inspection(cont.)pBall Measurement 2022-10-5u Peeling1st Bond Fail(1)Power too muchBase Force not enoughAl pad not fully cured or contamination between Al and oxide layer2022-10-5u Ball Lift1st Bond Fail(2)Ball LiftBall Lift With Pad PeelingBase Power not enoughMaterial problem 2022-
26、10-51st Bond Fail(3)pNeck CrackRD too highRH too lowWrong/over used capillaryWire Clamp gap too smallWire problemEFO Current too large 2022-10-5Off Center BallTail Length too longWire or Wire Path contaminationEFO Box or cable connection problemAir Tensioner flow too low 1st Bond Fail(4)pOff Center
27、Ball(Golf Ball)2022-10-5u Smash BallTail Length too shortWire or E-torch contaminationTip of tail length swing away from E-torch Smash Ball2022-10-5uMissing BallTail Length too shortFire Level too low or too highE-torch tip dirty2nd Bond Power/Force/Search Speed too high 2022-10-5With WeldWireCapill
28、ary MarkMissing WeldBroken WedgeLeadSufficient Wedge Width&LengthSecure Tool ImpressionNo Fish TailNo Damage/Broken WedgeBonding Weld InspectionpWeld Detection2022-10-5Broken Wedge2nd Bond Power/Force too highLead clamping not enough2nd Bond Fail(1)pBroken Wedge2022-10-5Lead floating or contaminatio
29、n2nd bond time,power,force too smallOver used capillary2nd Bond Fail(2)pLift Stitch2022-10-5Capillary Geometry2nd bond time,power,force too smallOver used capillary2nd Bond Fail(3)pStitch Peeling2022-10-5Wire ShortCapillary GeometryWire Path problemSecond Bond parametersAir Tensioner problem Looping
30、 Fail(Wire Short 1)pWire Sway2022-10-5Wire ShortCapillary GeometryWire Clamp Gap too bigTail BentAir Tensioner Force not enough Looping Fail(Wire Short 2)pLoop Base Bent2022-10-5Wire ShortCapillary GeometrySearch Delay setting not optimizedBase strength too weak,increase RD Looping Fail(Wire Short 3
31、)pExcessive Loop2022-10-5Floating leadsFriction along wire pathTrajectory selection is not goodWire on capillary is not good Looping Fail(Inconsistent)pInconsistent Looping2022-10-5Critical Parameters for Bondingu Bond Parameter Contact Time、Power、Force(for 1st&2nd Bond)u Base Parameter Base Time、Po
32、wer、Force(for 1st&2nd Bond)u Reference Parameter Search Height、Search Speed(for 1st&2nd Bond)u EFO Parameter Ball Size、FAB Size、EFO Time、EFO Current、EFO Voltage.u Looping Parameter R.H、R.D、Neck Angle、.2022-10-5Multi-tier Looping2022-10-5Stacked DieDie Thickness 80umTotal Die Height 850um2022-10-5Ult
33、ra Low LoopBell LoopEscargot LoopLoop HeightMinimum32 m.Maximum42 m.Mean37 m.Loop HeightMinimum40 m.Maximum47 m.Mean44 m.2022-10-5Short Wire LoopingDie edge to wire gap27.38 m mmDie edge to 2nd bond pt.124.3 m mm2022-10-5J WirepJ wire on 1st and 2nd kinkn Provide better wire clearance and mold sweep
34、 especially for the corner wires2022-10-5BSOB/BBOS/Pump BallBond Stitch On BallBond Ball On Stitch2022-10-5Bond Stitch On StitchSide View of 2nd BondTop View of 2nd BondTop View of Looping2022-10-5Multi-Ball&Flex Bump BallTop View of Multi-BallSide View of Multi-BallFlex Bump Ball ShapeLooping for Flex Bump Ball2022-10-5 END 2022-10-5
