(完整版)晶振工作原理及制程

Nov.20,2001IntroductionofQuartzCrystalLindaLin/FAEDepartmentContents

CharacteristicofQuartzMaterial

CharacteristicsofCrystalUnitsChoosetheRightCrystalUnit

CharacteristicsofQuartzMaterial

QuartzMaterial

PiezoElectricity

WhyisAT-Cut

Frequencyvs.Thickness

Lapping&EtchingQuartzMaterial(1)材料成份：二氧化矽SiO2

材料組成：正六方晶系

TRIGONAL-DIGONALCLASS：32

材料特性：熔點1,750℃@1atm

α-β相變點537℃@1atm

硬度~7.2莫氏硬度@25℃

密度2,648Kg/M3@25℃壓電特性Y軸：機械軸MECHANICALAXIS

光雙折性Z軸：光學軸OPTICALAXIS

QuartzMaterial(2)QuartzMaterial(3)

SYNTHETICQUARTZCRYSTALAUTOCLAVEHYDROTHERMALMETHODRAWMATERIAL：SilicaHIGHPRESSURE：800to2,000atmospheresHIGHTEMPERATURE：~400℃HIGHTEMP.STABILITY：±0.2℃LONGGROWTHTIME：1~6MonthHIGHPURITY：Infra-RedAbsorption(IRA)：3585CM-1

PiezoElectricity(1)Thepositiveelectric-fieldisinducedwhenthemechanicforcepulltheOxygenatomoutoforiginalposition.Thenegativeelectric-fieldisinducedwhenthemechanicforcepushtheOxygenatomtowardcenterposition.TheSiO2isalwaysinthestaticstateofelectricneutrial.PiezoElectricity(2)Whenaelectricfieldapplied,theinducedelectricfiledisgeneratedandforcetheOxygenatommoveoutward.TheSiO2isalwaysinthestaticstateofelectricneutral.Whenaelectricfieldapplied,theinducedelectricfiledisgeneratedandforcetheOxygenatommovecloser.

振動模式長度彎曲振動Length-widthflexure

伸縮振動Extensionalflexure

輪廓振動Faceshearflexure

厚度振動Thicknessshearflexure基本波：Fundamental3倍頻：3rdovertone5倍頻：5thovertoneWhyisAT-Cut(1)WhyisAT-Cut(2)FundamentalMovement3rdOvertoneMovement20Mhz60Mhz0.082mm0.082mm+-+-WhyisAT-Cut(2)LowFrequencyCT+380DT-520ET+660FT-570HighFrequencyAT+35015’BT-490

各種切割角度/溫度之關係WhyisAT-Cut(3)AT切割角度/溫度之關係WhyisAT-Cut(4)Frequencyvs.ThicknessAT-CutCrystalF

(MHz)=1670T

(um)F

(kHz)=1670T

(mm)orFrequency14.318MHz20.000MHz26.973MHz35.328MHzThickness0.116mm0.083mm0.062mm0.047mm

LapingMachinism

Laping&Etching(1)

SurfaceTreatment&EtchingLaping&Etching(2)AVG.sizeRoughnessInter-Crackumumum#50025622#80014310#100011.52.58#20006.51.13.5#30004.00.82.6#40002.70.51.3#60002.00.30.8#100000.600.080.05Note:Theroughnessandinter-crackdataaredependetonthequartzmaterialandthetypeofabbresive.RoughnessInter-CrackCharacteristicsofCrystalUnit

Structure&Process

EffectiveCircuitofCrystalUnit

ParameterofEffectiveCircuit

MeasureingtheCrystalParametersStructureofX’TAL–DipTypeStructureofX’TAL–SMDTypeMetalLidQuartzBlankCeramicBaseCoatedElectrodeXTALProcess(1)

DIP49UXTALBaseplatingBlankcleaningAnnealingAutomountFreq.adjustmentCuringSealingAgingF.Q.C.O.Q.C.X’TALProcess(2)

SMDX’TALAlignmentBlankcleaningBasePlatingBlankautomountCuringFreq.adjustmentAnnealingAutoseamweldingAgingFinalTestFineleaktestGrossleaktestLasermarkingF.Q.C.TapingEffectiveCircuitofXTAL

等效電路Co:ShuntCapacitanceCm:MotionalCapacitanceLm:MotionalInductanceRr:MotionalResistanceNote:“Motional“meanstheFrequencyDependency.ParametersofEffectiveCircuit(1)

C0：Static(Shunt)Capacitance：

一般C0<5.5pF以下(Dip49U)

一般C0<3.5pF

以下(SMD7.0*5.0)C0=0.02‧del‧fsnTheshuntcapacitanceincludethecapacitanceofXTALandstraycap.ofpaste,metalcap……insidethepackage.Mountingsystem的改變或base長度/材質不同

C0值會變化0.2pF~1pF之間.

C0小→起振電壓低，但CI較困難製造.2

Cm：dynamiccapacitanceC1=0.1‧Kc‧del‧fsn3f=ResonanceFreqencydel：ElectrodeDiametern：OrdinalNumberofHarmonics(1,3,5,7,..)kc：CorrectionConstantkc=1…fundamentaloscillationkc=0.85…3rdovertonekc=0.75…5rdovertoneParametersofEffectiveCircuit(2)2

Lm：DynamicInductance

L1=

1

Ws2C1低頻時，晶片較厚，WAFER較大…數HENRIES

高頻時，晶片較薄，BLANK較小…數mH

1

2fsC1=由MechanicalMass決定大小ParametersofEffectiveCircuit(3)

R1：DynamicResistance…….(Rr)

R=PLA，A↑，R↓相關原因：(1)音響學上的損失晶片表面平行度大氣R1>N2R1>真空中R1石英晶片表面清潔度晶片表面與鍍膜層附著性電極面之設計石英原料材質石英晶片表面處理ParametersofEffectiveCircuit(4)MeasuringtheCrystalParametersCalculationMethodMeasurementMethodPhysicalLoadMethodPiNetWorkMethodOscillationMethodChoosetheRightCrystal

PrincipleofOscillation

CharacteristicsofLoadCapacitance

Pullability&Trim&Q-value

ReadtheTestingDataSettingtheSpecificationPrincipleofOscillation振盪原理PrincipleofOscillation(1)振盪原理GainCurveofOscCircuitPrincipleofOscillation(2)振盪原理GainCurveofOscCircuitPrincipleofOscillation(3)振盪原理GainCurveofOscCircuitPrincipleofOscillation(4)負性阻抗(-R)

-RFrequency10.020.030.040.050.0從XTAL兩個端點向振盪線路看進去之頻率對阻抗關係CharacteristicofLoadCapacitance(1)CharacteristicofLoadCapacitance(2)LoadCapacitanceCL

CL=Cd‖Cg+Cs=Cg‧Cd/(Cd+Cg)+Cs

‧Cs：StrayCapacitance一般2~3pF

FL=FR*(1+C1/2*(C0+CL))‧CL愈小，Cs影響愈大，愈不穩定‧CL太大，雖Cs影響小，但power必須加大，耗電→建議：

CL以18~20pF為主

電容成本低不要省，

且應利用Cd/Cg來調整CL，

而非用X’TAL來就電容

CharacteristicofLoadCapacitance(3)FL=FR*(1+C1/2*(C0+CL))CL=Cd‖Cg+Cs

PullingRangeFromCL1~CL2：Pullability&Trim&Q-value(1)DL=FL1-FL2FR=C1(CL2-CL1)(C0+CL1)(C0+CL2)S=dFLdCL≒C12‧(C0+CL)2

TrimSesitivityatCL：

ExtremelyImportant

Pullability&Trim&Q-value(2)Pullability&Trim&Q-value(3)Fundor3rd?Fundor3rd?

Q值：thequalityofquartzXTALQ=2**Fr*LmR112**Fr*R1*Cm=IsthereanyrelationbetweenQ-valueandPullability?Pullability&Trim&Q-value(4)ReadtheData(1)ParTypeMode(F/O)Frequency.MHzCopFCmfFCLpFTrimPpm/pFRrOhm7.0*5.0Fund16.0003.011.032.04.49.06.0*3.5Fund16.0003.011.09.038.410ParTypeMode(F/O)Frequency.MHzCopFCmfFCLpFTrimPpm/pFRrOhm7.0*5.0Fund16.0003.011.01828.29.07.0*5.03Rd49.1522.80.8180.937ReadtheData(2)ReadtheData(3)ThisSpectrumisonlyshowninXTALunit.Notinexactoutputofoscillatedcircuit.Why?ReadtheData(4)ReadtheData(5)ReadtheData(6)SettingtheSpecification(1)

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