PCB Strain Roadshow -...

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PCB Strain Measurement 巨克富科技 Chief-SI Professional System Integrator

Transcript of PCB Strain Roadshow -...

  • PCB Strain Measurement

    Chief-SI Professional System Integrator

  • AgendaWhy need strain gages?IPC/JEDEC-9702/9704 StandardFundamental of strain gaugeStrain measurement requirementReport functionDemo

  • Why need strain gages?Board flexure induced solder ball cracking, trace damage, pad lifting

  • Trend of PCBFiner pitch of chipThickness of PCBLead free (RoHS)

    Brittle

    CSP

    BGA

  • Who should be concernedComponent suppliersTest-fixture vendorsPCB assemblersSystem manufactures

  • IPC StandardIPC/JEDEC-9702Monotonic Bend Characterization of

    Board-Level InterconnectsJune 2004

    IPC/JEDEC-9704Printed Wiring Board Strain Gage

    Test GuidelineJune 2005

  • IPC-9702Topics

    Monotonic Bend Test

    EquipmentUniversal tensile testerStrain measurement instrumentContinuity monitoring strain & resistance instrument

    Recording datastrain vs. timestrain-rate vs. timestrain vs. strain-rateforce vs. timeresistance vs. time

  • IPC-9702Universal tensile tester

    Control board deflection rate

    Measurement Instrument500 Hz min.Simultaneous recording strain & resistance

    Copy from IPC

    2008 Q1 will ready

  • IPC-9702Test board Daisy-chainUni-axial strain gage

    1.5 mm*1.5 mmPrincipal strain angle ~ longitudinal

    Test speedStrain rate:5000 /s

    Packagetype

    PCB

    Load span

    Strain gageGlobal PWB Strain

    Daisy-Chain

  • IPC-9704Topics

    Test setup and equipment requirementsStrain measurementReport format

    Surface mount deviceBGA (Ball Grid Array)SOP (Small Outline Package)CSP (Chip Scale Package)

    June 2005

  • IPC-9704Process need strain measurement

    SMT assemblyComponent/connector install

    Board test processesICT, Function test

    Mechanical assemblySystem assembly

    Shipping Environment

    Copy from IPC

  • IPC-9704Strain Measurement Instrument

    Simultaneous sampling500 Hz min. for impulse event

    ICT, Drop, 100 Hz min. for assembly processes3-wire gage with low level excitation (typical 2V)Low Pass filterMore than 3 channels(12 or more recommend)

  • IPC-9704Analysis

    Principal strainPeak valueStrain rateTime history

    Test FrequencyBefore any test or assembly fixture is brought online.Whenever there are modifications to a test fixture that might

    alter the strain profile.Whenever there are modifications to an assembly process

    that might alter the strain profile.In-process stiffener design validation.Enclosure design validation prior to hard-tooling

  • Fundamental of strain gage

    Copy from Vishay

  • What is strain?

    Copy from TMLin/in

  • Principle of strain gage

    Copy from TML

  • Strain gage types

    Uniaxial Rosette(Tee) Rosette(Rectangular)Resistance1203501000

    Axis:

    MaterialSteelAluminumPlasticCompoundTemperatureRoom temperatureHigh temperature(500)

    Measure direction

    ApplicationResidual stressCrack detectionShear

  • Gage (IPC 9704)RosetteStacked Rosette Strain Gages with pre-attached wires

    Planar Stacked

  • Gage position (IPC 9704)

  • Strain gage Attachment

  • Common question of Strain measurement

    1. Strain2. Strain Gage3. Noise4.

    5.

    6.

  • How to measure strain?

    Bridge Four bridge armsExcitation voltageOne Gauge system

    Two-wire circuitThree-wire circuit (Lead wire compensation)

  • The Wheatstone BridgeFull Bridge

    LoadcellStrain type AccelerometerTorque Transducer

    Half BridgeStrain with Thermal compensationWeighting scale

    Quarter BridgeStrain

  • Features Large excitation, large signal outputThermal consideration

    Optimum excitationGauge grid areaGauge resistanceMounting surface

    +2.5 VDC for StrainMap

    Optimum Excitation Voltage

    0 to 10 V1000

    0 to 10 V350

    0 to 3.125 V120

    Full Bridge

    0 to 10 V1000

    0 to 10 V350

    0 to 6.250 V120Quarter Bridge

    Excitation Voltage

    ResistanceConfiguration

    RVIVPower

    2

    ==

  • Strain vs.

    1 ~

    4167

    GF=2, R=120 , R=1

    R

    RGF

    4167004167.02120/1

    ===

    =GF

    RR

    GF=2, R=350 , R=1

    1429001429.02350/1

    ===

    =GF

    RR

    = 00024.04167

    11

    = 0007.01429

    11

  • Calibration(Shunt)

    Add Large ResistorSimulate Strain predeterminedExample

    Rgauge=120 Rshunt=100 kR=0.1438 599.3

    Shunt

  • Principal strain and Mohrs circle

    yx

    xyp

    xyyxyx

    xyyxyxx

    =

    +

    +=

    +

    ++

    =

    2tan

    222

    2sin2

    2cos22

    22

    2,1

    Known: 45,,, = xyx

    2,1 :Principal strainp :Principal direction

    2

    +0,

    2yx

    ( )0,1( )0,2

    +

    2,

    2max yx

    2

    , xyx

    2, xyy

    p2

  • Example for 0-45-90 Rosette

    45

    45b

    c

    a x

    y

    480300

    650

    ==

    =

    c

    b

    a

    2.421739304

    1434

    max

    2

    1

    ===

    =

    p

    450520800

    ===

    c

    b

    a

    80360520

    ===

    c

    b

    a

    4.14

    1428539

    889

    max

    2

    1

    =

    ==

    =

    p

    5.12662111

    551

    max

    2

    1

    ===

    =

    p

    :unit

  • Strain Measurement SolutionStrainMap

    Simultaneous sampling3 noise level2k/ch(5k/ch for PCI bus)24~128 ch

    StrainMap EnhancedSimultaneous sampling5 noise level50k/chUSB24~56 chVibration Module (Option)

  • Our CustomerASUSCompalInventecLenovoTSMC

    IntelFoxconnCHIMEIPTI

  • StrainMap advantageTotal solution

    Integrate Gagemeasure & Training

    Performanceaccuracy3Simultaneous sampling 2k

    (5k for PCI busChannelup to 128 Chsstability

    Analysis & report functionAuto-calibration (Shunt)Mohrs circle analysisExcel report

    Easy wiringShort lead time & lower priceLocal service

  • Easy wiring

  • Software for IPC-9704Graphical User InterfaceEasy WizarCalculation

    Diagonal strain = e1-e2+e3Principal StrainStrainRate

  • Report of StrainMap

  • StrainMap EnhancedDemo

  • Thank you

    Chief SI

    03-59362680922855439