ESD Awareness_Customer

1、ESD Awareness TrainingJuly 2008 Page 211/1/2021 confidential lBasics of ESDlCharging MechanismlESD ModelslESD risk assessment and EPA identificationlESD control at EPA EntrancelProtective MeasureslESD protection system (summary)lApproaches in ESD ProtectionlESD Vs EOSlESD EquipmentContentsPage 311/1

2、/2021 confidential Basics of Electrostatic Discharge (ESD)Page 411/1/2021 confidential ESD What is ESD?ESD = ElectroStatic DischargeIt is the rapid transfer of electrostatic charges between two bodies at different electrostatic potentials.Transfer of electronsTransfer of electrons- 5 kV - 3 kV- 5 kV

3、Page 511/1/2021 confidential Explosion of the hydrogen filling of the airship Hindenburg“ during the landing in Lake Hurst, New Jersey (1937).Result: 38 dead peopleHistoric ESD EventsPage 611/1/2021 confidential ESD Susceptibility of DevicesAlmost all types of devices are susceptible to ESD damages

4、irrespective of active or passive typesTechnology/Product HBM ESD withstand level (V)MOSFET 100-200LED 50-200Diode Lasers 100-2000Bipolar Op Amp 400-1000Schottky Diode 300-2500CMOS Mixed Signal Devices (0.8um) 600-1700Low power transistors 300-5000MR/GMR Heads 5-50 Page 711/1/2021 confidential ESD D

5、amage - Power TransistorMagnification : 4870 xMagnification : 12xPage 811/1/2021 confidential DrainGateSourceGateoxide damage at Gate-Source edge of a transistorTypical failure signaturePage 911/1/2021 confidential Typical electrostatic voltages (V)Page 1011/1/2021 confidential People do not feel“ m

6、ost of the ESD events!(sensitivity threshold 3000 V)Danger of unnoticed ESD EventsPage 1111/1/2021 confidential Types of ESD Impact on a semiconductor deviceWhen a static discharge event occurs, what happens to ESDS devices ?Two types of impact Catastrophic (outright) failure Latent (walking wounded

7、) defect Page 1211/1/2021 confidential Types of ESD Impact on a semiconductor device Catastrophic FailureThe device does not meet design performance standards Latent defectThe device meets design performance standards but fails before end of intended design lifePage 1311/1/2021 confidential Charging

8、 MechanismPage 1411/1/2021 confidential Charge separation in a neutral object Charge flow during contact to groundRemaining charge after separation Remaining charge after removing the charged jamming object + + + + + + + + + + + + + + + + -Charging by InductionPage 1511/1/2021 confidential Charging

9、By Contact and SeparationThe Triboelectric ChargeNumber of Electrons Stripped From, orAccumulated on a Material is its Charge (Q).Depending on Capacitance (C), Voltage (V) will Vary With Charge (Q).Q = CVPage 1611/1/2021 confidential Charging By Contact and SeparationUnderstanding Static Electricity

10、 :The Atom- e = 1.6 x 10-19 Coulomb (C)Proton+-eElectronNeutronPage 1711/1/2021 confidential Charging By Contact and SeparationThe Triboelectric Charge Begins When2 Materials Make Intimate Contact-e-e-e-e-e+-e-e-e-e-e+Material A5+5-0 No ChargeMaterial B5+5-0 No ChargeContactPage 1811/1/2021 confiden

11、tial Charging By Contact and SeparationThen Separate; One Materials StripsAn Electron (-) from the Other-e-e-e-e+-e-e-e-e-e+Material A5+4-1+ Positive ChargeMaterial B5+6-1- Negative ChargeSeparation-ePage 1911/1/2021 confidential Charging By Contact and SeparationTriboelectric Charge - Cause greater

12、 than 95% of all ESD problems)Factors that determine the magnitude and polarity of the charges Contact pressure Speed of separation Relative humidity Type of surfacesReal-life examples Walking across the floor Standing up from a sitting positionPage 2011/1/2021 confidential ESD ModelsPage 2111/1/202

13、1 confidential ESD Models Human Body Model (HBM) Machine Model (MM) Charged Device Model (CDM) Field Induced Model (FIM)Page 2211/1/2021 confidential Definition of ESD Models Human Body Model (HBM)Discharge from a person onto an ESDS device. Page 2311/1/2021 confidential Human Body Model (HBM)Page 2

14、411/1/2021 confidential HBM ESD Sensitivity (Withstand Voltage) AssessmentClass Voltage Range (V) 0 250 1A 250 to 500 1B 500 to 1,000 1C 1,000 to 2,000 2 2,000 to 4,000 3A 4,000 to 8,000 Source :ESD Association standard test method ANSI/ESD STM 5.1-2001 Page 2511/1/2021 confidential Definition of ES

15、D ModelsMachine Model (MM)Discharge from a floating metallic machine element onto an ESDS device.Page 2611/1/2021 confidential Machine Model (MM)Bond tool (metallic)The metallic bond toolmounted on the bond head assembly is moving very fast during wire bonding. If it is not grounded properly, danger

16、ous high voltage can be generated due to tribo-charging. MM ESD event takes place when the bond tool is in contact with the bond pad of ICs.Page 2711/1/2021 confidential MM ESD Sensitivity (Withstand Voltage) AssessmentClass Voltage Range (V) M1 100 M2 100 to 200 M3 200 to 400Typically, the MM ESD w

17、ithstand voltage of a device is 10 times lower than HBM Source : ESD Association standard test method ESD STM 5.2-1999Page 2811/1/2021 confidential Definition of ESD Models Charged Device Model (CDM)Discharge from a charged device to a hard ground (Metallic containers, metallic pick up tools, tweeze

18、rs and in general any objects which is metallic) Page 2911/1/2021 confidential Charge Device Model (CDM) After lead cutting After lead cutting, ,the device drop the device drop onto a metalic plate (hard ground) with onto a metalic plate (hard ground) with lead facing down wards - potential lead fac

19、ing down wards - potential hard hard dischargedischargePage 3011/1/2021 confidential Definition of ESD Models Field Induced Model (FIM)Discharge from an ESDS device to a hard ground in the presence of static field.Page 3111/1/2021 confidential Charge separation in a neutral objectHard dischage takes

20、 place if the pin is in contact with metal or hard ground + + + + + + + + -Field Induced Model (FIM)Page 3211/1/2021 confidential Field Induced Model (FIM) Field induced Model ESD event takes place if the device pin is in contact with hard groundCRTE-FieldLines+_Page 3311/1/2021 confidential CDM ESD

21、 Sensitivity AssessmentClassVoltage RangeC1 125C2125 to 250C3250 to 500C4500 to 1,000C51,000 to 1,500C61,500 to 2,000312.6- 1.2410Plate ControlsVoltage AdjustSource : ESD Association standard testmethod ESD STM 5.3.1-1999Page 3411/1/2021 confidential ESD Hazard of Electronic DevicesESD-TestSIEMENSWa

22、ferDeviceBoardSystemESD-HazardSIEMENS Future 0202Page 3511/1/2021 confidential ESD Risk Assessment and EPA IdentificationPage 3611/1/2021 confidential ESD Risk Assessment ESD risk assessment is a pre-requisite to identify the protection measures required for the various processes As soon as the ESD

23、risk of the various processes is identified, the right ESD protection can be put in place Depending on the required ESD protection measures, certain areas may need to be classified as ESD Protected Area (EPA)Page 3711/1/2021 confidential ESD Protected Area (EPA)PrintPick & PlaceIR ReflowPackingA

24、ssembly LineEPAAn EPA may encompass a single workstation, a room, or a building.BuildingWorkstationUPAEPARoomEPAEPAUPAUPAUPAStorage (Materials)Storage (Products)UPA = Unprotected AreaPage 3811/1/2021 confidential ESD Control At EPA EntrancePage 3911/1/2021 confidential Footwear Tester Set UpSet up A

25、Door sensorFootwear tester with magnetic controlled doorPage 4011/1/2021 confidential Footwear Tester Set UpSet up BFootwear tester with turnstilePage 4111/1/2021 confidential Footwear Tester Set UpSet up CFoot wear tester with turnstile new designPage 4211/1/2021 confidential Proper Attire (Smock)C

26、orrectIncorrectPage 4311/1/2021 confidential CorrectIncorrectProper Attire (Smock)Page 4411/1/2021 confidential Protective MeasuresPage 4511/1/2021 confidential ESDS basic symbolEPA sign LabelsPage 4611/1/2021 confidential LabelsEquipment labelPage 4711/1/2021 confidential ClassroomVideoSoftwareTrai

27、ning must be documented!Periodic trainingPeriodic Training (Refresher training once every two years)Page 4811/1/2021 confidential Normal garments cangenerate dangeroushigh fields!Normal shoes are not able to drain off chargefrom human bodies!Protective GarmentsPage 4911/1/2021 confidential Special g

28、armentsdo not show dan-gerous fields!Dissipative footwear drains off charge on human bodiesin a controlled way!Dissipative footwearavoids charging by walking!Special garments alsocompensate the fieldgenerated by the nor-mal clothes if they areproperly fastened!Protective GarmentsPage 5011/1/2021 con

29、fidential Avoid a ”hard“ discharge!metallic surfaceHandlingPage 5111/1/2021 confidential Unpack the devicesand place them on dissipative materialto drain off possible charge on the devices ”softly“Dissipative table matHandlingPage 5211/1/2021 confidential ESD Protective Materials Metallic shielding

30、bagMoisture barrier bagPage 5311/1/2021 confidential ESD Protective MaterialsESD protective packing tubes/trays/boxes Corrugated conductive boxPage 5411/1/2021 confidential ESD Protective Materials Static dissipative plastic bagFinger cotsPage 5511/1/2021 confidential IonizersInsulators are poor ele

31、ctrical conductorsIt is not possible to drain away charges accumulated in insulators by connecting a ground wire to insulatorsOne of the methods to remove the charges quickly and effectively is to neutralise the insulators with ionisersPage 5611/1/2021 confidential Packing Requirement Page 5711/1/20

32、21 confidential Intimate packing:Packing material in direct contact with the component (e.g. shipping tube)Proximity packing:Packing material not in direct contact with the component(e.g. carton box)L = low charging:Packing exhibiting properties which minimize any charge generationPacking Definition

33、sPage 5811/1/2021 confidential C = Conductive (Surface or Volume):Packing material with a resistance, R 104 D = Dissipative (Surface or Volume):Packing material with a resistance, 104 R 1011 .I = insulative (Surface or Volume) :Packing material with a resistance, R 1011 .S = electrostatic field shie

34、lding:A barrier or enclosure that protects devices against electrostatic field.The surface resistance is, R 104 .Packing DefinitionsPage 5911/1/2021 confidential Inside EPAOutside EPAIntimate Proximity Intimate ProximityESDSL+C orL+DL+S orL+C orL+DL+C orL+DSNonESDSD or LNo requirementsPacking Requir

35、ementsPage 6011/1/2021 confidential Packing Requirements-SMT ManufacturingPacking requirement outside EPA :Low ChargingDissipativeShieldingPacking requirement within EPA :Low ChargingDissipativeoptional :ShieldingTransportationTransportationShippingStorage(product)Product DevelopmentInspectionPre-As

36、semblyRework / AssemblyQA / TestAdmin. OfficesEngineeringMaintenancePrintPick & PlaceIR ReflowPackingPrintPick & PlaceIR ReflowPackingAssembly LineStorage (materials)Field ReturnsPoint of UsePage 6111/1/2021 confidential Summary of ESD Protection Measures which addresses the respective ESD M

37、odelsPage 6211/1/2021 confidential Protection against HBM ESD events1 Requirement : Personnel Grounding 1)Wrist Strap System2)Flooring-Footwear SystemThe total resistance of the system from the person, through the footwear (or through the chair) and flooring to the ground to be less than 1x109 ohms

38、or body voltage to be less than 100V (Reference to ESD Standard ANSI/ESD S20.20 or IEC 61340-5-1)Page 6311/1/2021 confidential Protection against HBM ESD eventsPersonnel Independent solution for grounding of operatorsConductive floor/footwear system is used for personnel groundingAreas identified as

39、 ESD Protected Areas (EPA) are partitionedFootwear test at entrance to EPAEntrance door/control gate interlock opens only with positive footwear test results A Well defined footwear resistance, chair resistance and the floor resistance results in the total resistance of the system to be less than 1x

40、109 ohms or body voltage to be less than 100VPage 6411/1/2021 confidential Personnel Grounding Standing OperationSystem Rtg (Resistance to ground) MeasurementRequirement : Rtg 1.0 x 109 ohms (ANSI/ESD STM 97.1)Actual: Rtg 2.2 x 106 ohmsPage 6511/1/2021 confidential Personnel Grounding Standing Opera

41、tionBody Voltage MeasurementRequirement : 100 V (ANSI/ESD STM 97.2)Actual: 10 VWalkingPage 6611/1/2021 confidential Personnel Grounding Sitting OperationSystem Rtg (Resistance to ground) MeasurementRequirement: Rtg 1.0 x 109 ohms (Reference:ANSI/ESD STM 97.1)Actual: Rtg 2.6 x 106 ohmsPage 6711/1/202

42、1 confidential Personnel Grounding Sitting OperationBody Voltage MeasurementRequirement : 100 V (Reference: ANSI/ESD STM 97.2)Actual: 10 VRolling from left to rightPage 6811/1/2021 confidential Personnel Grounding Sitting OperationTurning from left to rightBody Voltage MeasurementRequirement : 100 V

43、 (Reference: ANSI/ESD STM 97.2)Actual: 50sDuration orders of mJLimited energy J - few mJExtensive physical damageLittle damageEOS And ESD FailuresPage 9011/1/2021 confidential Sources of EOS Failuresn Manufacturing Processn Electrical soldering/desoldering hand toolsn Cable discharge events cable pl

44、ug in and out of socketn Ungrounded equipment and machinesn PCB design and layoutn Board design effects on ESD immunity of the circuit boardn Field Application n Cable discharge eventsPage 9111/1/2021 confidential Manufacturing Process Soldering/Desolderingn Ungrounded Soldering/Desoldering Tooln In

45、duced AC voltage at the soldering tip. The magnitude depends on the quality of groundingn Accumulation of static voltage due to tribochargingn Remedial Measuresn Ensure that the soldering iron is grounded properlyn Reference to ESDA Standard Test Methods ESD STM13.1-2000o Resistance measurement (col

46、d iron) Resistance between the ground pin of unpluged socket and iron tip shall be less than 2 ohmso Soldering iron tip AC voltage measurement (Hot iron) AC voltage between the soldering iron tip and AC power ground shall be less than 20 millivoltPage 9211/1/2021 confidential Manufacturing Process C

47、able Discharge Eventsn Cable discharge events (CDE)n The result of charged cables being connected to electronic productsn Cable with a plug is used as a test proben The cable get charged up under the continuous action of plugging the cable into the socket of Device Under Test (DUT)n A discharge will

48、 take place when the plug is in contact with the contact pins inside the socketn Remedial Measuresn Measure e-field to verify whether cable/plug is chargedn If charge is present, look for alternative material for the cable and plugn Antistatic spray could be used as short term solutionPage 9311/1/20

49、21 confidential Manufacturing Process Ungrounded Equipmentn Ungrounded equipment/machinesn Induced AC voltage at the ungrounded portion of the machine. The magnitude depends on the quality of groundingn Accumulation of static voltage due to tribochargingn Remedial Measuresn Ensure that the equipment

50、 is grounded properlyn Reference to ESDA Standard Practice ESD SP10.1-2000o Resistance measurement Resistance between the moving parts of the machine and AC power ground shall be less than 1 megohmo AC voltage measurement AC voltage between the moving parts of the machine and AC power ground shall be less than 100 millivoltPage 9411/1/2021 confid