Electronic components - Reliability - Reference conditions for failure rates and stress models for conversion

Gives guidance on the use of failure rate data for the reliability prediction of components in electronic equipment. Reference conditions for failure rate data are specified, so that data from different sources can be compared. The reference conditions adopted are typical of the majority of applications of components in equipment (e.g. telecommunication use, data processing). In this standard it is assumed that the failure rate used under reference conditions is specific to the component i.e. it includes the effect of complexity, technology of the casing, dependence on manufacturers and the manufacturing process, etc.

Bauelemente der Elektronik - Zuverlässigkeit - Referenzbedingungen für Ausfallraten und Beanspruchungsmodelle zur Umrechnung

Composants électroniques - Fiabilité - Conditions de référence pour les taux de défaillance et modèles d'influence des contraintes pour la conversion

Donne des recommandations pour l'emploi de taux de défaillance destinés à des prévisions de fiabilité de composants d'équipements électroniques. Il est défini des conditions de référence pour les taux de défaillance de façon à permettre des comparaisons de données de taux de défaillance ayant différentes origines. Les conditions de référence choisies sont représentatives de la plupart des applications des composants dans les équipements (par exemple les télécommunications, les calculateurs). On suppose dans cette norme que le taux de défaillances donné dans les conditions de référence est représentatif du composant, c'est-à-dire ui'il tient compte des effets de la complexité, du type de boitier, de l'influence des fabricants et des procédés de fabrication etc.

Electronic components - Reliability - Reference conditions for failure rates and stress models for conversion (IEC 61709:1996)

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Status
Withdrawn
Publication Date
31-Aug-2002
Withdrawal Date
10-Jun-2014
Current Stage
9900 - Withdrawal (Adopted Project)
Start Date
11-Jun-2014
Due Date
04-Jul-2014
Completion Date
11-Jun-2014

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Electronic components - Reliability - Reference conditions for failure rates and stress models for conversion (IEC 61709:1996)Bauelemente der Elektronik - Zuverlässigkeit - Referenzbedingungen für Ausfallraten und Beanspruchungsmodelle zur UmrechnungComposants électroniques - Fiabilité - Conditions de référence pour les taux de défaillance et modèles d'influence des contraintes pour la conversionElectronic components - Reliability - Reference conditions for failure rates and stress models for conversion31.020Elektronske komponente na splošnoElectronic components in general21.020Characteristics and design of machines, apparatus, equipmentICS:Ta slovenski standard je istoveten z:EN 61709:1998SIST EN 61709:2002en01-september-2002SIST EN 61709:2002SLOVENSKI
STANDARD



SIST EN 61709:2002



SIST EN 61709:2002



SIST EN 61709:2002



SIST EN 61709:2002



SIST EN 61709:2002



NORMEINTERNATIONALECEIIECINTERNATIONALSTANDARD1709Première éditionFirst edition1996-10Ó CEI 1996
Droits de reproduction réservés
¾ Copyright - all rights reservedAucune partie de cette publication ne peut être reproduite niutilisée sous quelque forme que ce soit et par aucun procédé,électronique ou mécanique, y compris la photocopie et lesmicrofilms, sans l'accord écrit de l'éditeur.No part of this publication may be reproduced or utilizedin any form or by any means, electronic or mechanical,including photocopying and microfilm, without
permissionin writing
from the publisherBureau central de la Commission Electrotechnique Internationale
3, rue de Varembé
Genève, Suisse Commission Electrotechnique Internationale International Electrotechnical
CommissionCODE PRIXPRICE CODEPour prix, voir catalogue en vigueurFor price, see current
catalogueXComposants électroniques
–Fiabilité –Conditions de référence pour les taux dedéfaillance et modèles d’influence descontraintes pour la conversionElectronic components –Reliability –Reference conditions for failure ratesand stress models for conversionSIST EN 61709:2002



1709 ã IEC:1996- 3 -CONTENTSPageFOREWORD.5INTRODUCTION.7Clause1 Scope.92 Normative references.93 Definitions.94 Symbols.115 Reference conditions.156 Generic stress models.217 Specific stress models.27AnnexesA
Limitations of reliability models and predictions.67B Examples.77C Bibliography.83SIST EN 61709:2002



1709 ã IEC:1996- 5 -INTERNATIONAL ELECTROTECHNICAL COMMISSION_________ELECTRONIC COMPONENTS -Reliability -Reference conditions for failure ratesand stress models for conversionFOREWORD1)The IEC (International Electrotechnical Commission) is a worldwide organization for standardizationcomprising all national electrotechnical committees (IEC National Committees). The object of the IEC is topromote international co-operation on all questions concerning standardization in the electrical and electronicfields. To this end and in addition to other activities, the IEC publishes International Standards. Theirpreparation is entrusted to technical committees; any IEC National Committee interested in the subject dealtwith may participate in this preparatory work. International, governmental and non-governmental organizationsliaising with the IEC also participate in this preparation. The IEC collaborates closely with the InternationalOrganization for Standardization (ISO) in accordance with conditions determined by agreement between thetwo organizations.2)The formal decisions or agreements of the IEC on technical matters, express as nearly as possible, aninternational consensus of opinion on the relevant subjects since each technical committee has representationfrom all interested National Committees.3)The documents produced have the form of recommendations for international use and are published in theform of standards, technical reports or guides and they are accepted by the National Committees in thatsense.4)In order to promote international unification, IEC National Committees undertake to apply IEC InternationalStandards transparently to the maximum extent possible in their national and regional standards. Anydivergence between the IEC Standard and the corresponding national or regional standard shall be clearlyindicated in the latter.5)The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for anyequipment declared to be in conformity with one of its standards.6)Attention is drawn to the possibility that some of the elements of this International Standard may be thesubject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights.International Standard IEC 1709 has been prepared by IEC technical committee 56:Dependability.The text of this standard is based on the following documents:FDISReport on voting56/494/FDIS56/534/RVDFull information on the voting for the approval of this standard can be found in the report onvoting indicated in the above table.Annexes A, B and C are for information only.SIST EN 61709:2002



1709 ã IEC:1996- 7 -INTRODUCTIONFailure rate data are useful in the design phase of electronic equipment. They can be used toidentify potential reliability problems, the planning of logistic support strategies and theevaluation of designs and reliability predictions. Predictions are essentially probabilitystatements which are based on the failure rates of electronic components. These predictionsshould be carried out before hardware realization and/or the procurement process of anequipment.Unsubstantiated failure rate data used in reliability predictions can cause inaccuracies. Theseinaccuracies can be reduced by post processing supplied failure data to remove information onreplacements that are not real failures. Failure rate data should include knowledge of the failurecriteria and the mechanical and electrical stresses which have resulted in the componentfailure. This International Standard serves as a guide to describe reference conditions for whichfield failure rates should be stated. This then allows, by the use of stress models, extrapolationto other operating conditions. Some of the limitations of the models are outlined in annex A. Itis not intended to replace other valid handbooks.The reference conditions adopted are typical of the majority of applications of components inequipment (e.g. telecommunication use, data processing). In this standard it is assumed thatthe failure rate used under reference conditions is specific to the component i.e. it includes theeffect of complexity, technology of the casing, dependence on manufacturers and themanufacturing process, etc.The component failure rates to be used with this standard are to be determined based uponagreement between the component manufacturer and the component user, using one or moreof the following sources: equipment manufacturer data book, equipment user data book,component manufacturer data book or data from an independent third body. Sources should bethe latest available that are applicable to the product and its specific use conditions. Ideally,failure rate data should be obtained from the field.The stress factors for different conditions are specified in this standard. They are typical valuesfor the individual component classes from various manufacturers. When actual conditions ofuse are in close agreement with reference conditions, then as a first approximation the agreedcomponent failure rates can be used. The stress factors should be used, when they are knownto be correct or as an approximation, if nothing else is known. Where they are applied, their useshould be clearly stated. If other factors are known to be correct, they should be stated andused.SIST EN 61709:2002



1709 ã IEC:1996- 9 -ELECTRONIC COMPONENTS -Reliability -Reference conditions for failure ratesand stress models for conversion1 ScopeThis International Standard gives guidance on the use of failure rate data for the reliabilityprediction of components in electronic equipment. Reference conditions for failure rate data arespecified, so that data from different sources can be compared on a uniform basis. If failurerate data are given in accordance with this standard then no additional information on thespecified conditions is required.The stress models described in this standard should be used as a basis for conversion of thefailure rate data at reference conditions to the actual operating conditions. Conversion of failurerate data are only permissible within the specified functional limits of the components (seeannex A).2 Normative referencesThe following normative documents contain provisions which, through reference in this text,constitute provisions of this International Standard. At the time of publication, the editionsindicated were valid. All normative documents are subject to revision, and parties toagreements based on this International Standard are encouraged to investigate the possibilityof applying the most recent editions of the normative documents indicated below. Members ofIEC and ISO maintain registers of currently valid International Standards.IEC 50(191): 1990, International Electrotechnical Vocabulary (IEV) -
Chapter 191: Depend-ability and quality of serviceIEC 721-3-3: 1994,
Classification of environmental conditions - Part 3: Classification of groupsof environmental parameters and their severities - Section 3: Stationary use at weather-protected locations3 DefinitionsFor the purpose of this International Standard, the following definitions apply:3.1failure: Termination of the ability of an item to perform a required function. [IEV 191-04-01]3.2failure rate: Limit, if this exists, of the ratio of the conditional probability that the instant oftime, T, of a failure of an item falls within a given time interval, (t, t + DT) and the length of thisinterval, DT, when DT tends to zero, given that the item is in an up state at the beginning of thetime interval. [IEV 191-12-02].The characteristic preferred for reliability data of electronic components is the failure rate asdefined in IEV 191-12-02 (see also A.3).NOTE
In this definition T may also denote the time to failure or the time to first failure, as the case may be.SIST EN 61709:2002



1709 ã IEC:1996- 11 -3.3mean failure rate: Mean of the failure rate over a given time interval. [IEV 191-12-03,modified]3.4reference conditions: Reference conditions selected so as to correspond to the majorityof applications of components in equipment.3.5reference failure rate: Failure rate stated under the reference conditions given in thisstandard.NOTE – Reference failure rates are not necessarily equal because of the unquantifiable nature of themanufacturing processes and the assembly stages of components into equipment. However, failure ratevalues are found in practice to have similarities from one analysis to another. It is therefore suggested thatthe use of reference failure rate values can provide comparative information between different componentcategories and act as a useful guide for reliability calculations.3.6
failure criterion: Condition for the presence of a failure.NOTE – The failure criterion will also depend on the application of the component.3.7operating mode: Operating mode states whether components are continuously stressedduring their operation. A distinction is made between continuous duty and intermittent duty.Continuous duty is defined as operation for a long duration with constant or changing loads(e.g. process controls, telephone switch).Intermittent duty is defined as operation with constant or changing loads during up state (e.g.numerical controls for machinery, road traffic signals).3.8
prediction: Process of computation used to obtain the predicted value(s) of a quantity.[IEV 191-16-01]NOTE – The term “prediction” may also be used to denote the predicted values of a quantity.4 SymbolsIn this standard, the following symbols are used:lfailure rate under operating conditionslreffailure rate under reference conditionspUvoltage dependence factorpIcurrent dependence factorpTtemperature dependence factorpESelectrical stress dependence factorpSswitching rate dependence factorqambambient temperature in degrees CelsiusTambambient temperature in kelvinsqamb,refreference ambient temperature in degrees CelsiusTamb,refreference ambient temperature in kelvinsqrefreference temperature in degrees CelsiusTrefreference temperature in kelvinsSIST EN 61709:2002



1709 ã IEC:1996- 13 -DTrefreference self-heating in degrees CelsiusDTactual self-heating in degrees Celsiusq1 in degrees Celsius:–for integrated circuits the reference virtual (equivalent) junctiontemperature*;–for discrete semiconductors and optoelectronic components the referencejunction temperature;–for resistors the average reference temperature of the resistor element;–for inductors the average reference temperature of the winding;–for capacitors the reference temperature of the capacitor;–for other electronic components the reference temperature of thecomponent.q2 in degrees Celsius:–for integrated circuits the actual virtual (equivalent) junction temperature;–for discrete semiconductors and optoelectronic components the actualjunction temperature;–for resistors the average actual resistor element temperature;–for inductors the average actual winding temperature;–for capacitors the actual capacitor temperature;–for other electronic components the actual ambient temperature.Uoperating voltageUrefreference voltageUratrated voltageIoperating currentIrefreference currentIratrated currentPoperating power dissipationPrefreference power dissipationPratrated power dissipationRththermal resistanceRth,ambthermal resistance (to the environment)_________* In IEC 747-1, the virtual temperature Tvj is defined as internal equivalent temperature: a theoretical temperaturewhich is based on a simplified representation of the thermal and electrical behaviour of the semiconductordevice.NOTES1 For junction semiconductor devices, this term is sometimes called virtual (equivalent) junction temperature.2The virtual temperature is not necessarily the highest temperature in the device.SIST EN 61709:2002



1709 ã IEC:1996- 15 -5 Reference conditions5.1 GeneralFactors to be specified as reference conditions for failure rate data of components are given in5.2 to 5.7.5.2 Time period (operating phase)Reliability data for components apply normally to the constant failure rate period (see A.3, endof early failure period to beginning of wear-out failure period).If early failures are still to be expected for a component, the beginning of the phase of constantfailure rate should be specified. For components that are operated into their wear-out failureperiod (for example, end of incandescent lights and relays), the mean failure rate (see 3.3) isused up to the useful life, as given in the specifications.5.3 Failure criterionFailures, for the purpose of this standard, include both complete failures and parametric driftfailures (outside limits) which lead to failure of the included item in most applications. The limitsof the maximum permissible deviations for parametric drift failures should be specified inparticular specifications (see A.3).Failures as described above may not be the same as "specification failure", i.e. failures againstthe component detail specification. Where differences exist they should be clearly stated.5.4 Operating modeThe operating mode is continuous operation, if not otherwise specified in 5.7 (for example,intermittent).5.5 Climatic and mechanical stressesTable 1 – Reference conditions for climatic and mechanical stressesType of stressReference condition 1)Ambient temperature 2)qamb, ref = 40 °CClimatic conditionsClass 3K3 as per IEC 721-3-3Mechanical stressClass 3M3 as per IEC 721-3-3Special stresses 3)None1)
The failure rates stated under these conditions apply only to components not damaged during transport andstorage.2)
The ambient temperature for the purpose of this standard is the temperature of the medium next to thecomponent (which is considered as not operating) during equipment operation. The surroundings of thecomponent should be defined.3)
Wind, rain and snow, icing, drips, sprays or jets of water, dust (chemically active or not), effects of animalpests, corrosive gases, radioactive radiation, temperature cycling, etc.SIST EN 61709:2002



1709 ã IEC:1996- 17 -5.6 Electrical stressesThe reference conditions for electrical stresses are specified according to the type ofcomponent. Table 2 provides a summary. Additional points are specified for various casesin 5.7.Table 2 – Reference conditions for electrical stresses – SummaryType of componentReference conditions 1)Notes onself-heatingIntegrated semiconductorcircuitsFor digital CMOS:Uref = 5 VFor bipolar analogue circuits:70 % of rated voltage (Uref / Urat = 0,7)For other integrated circuits:operating voltage specified or else operating voltage 15 %under rated value given in specificationsThe reference self-heating DTref shall be given.Pref ´ Rth,ambTransistors, diodes,
powersemiconductors2)For transistors:50 % of rated voltage (Uref / Urat = 0,5)The reference self-heating DTref shall be given.Pref ´ Rth,ambPhototransistors,photodiodes, light-sensitiveresistors, photoelements,optocouplers, LEDs andIREDsFor phototransistors:50 % of rated voltage (Uref / Urat = 0,5)For light-emitting and infrared-emitting diodes:50 % of rated current (Iref / Irat = 0,5 )The reference self-heating DTref shall be given.Pref ´ Rth,ambResistors and
resistornetworks50 % of rated power at 40 °C (Pref / Prat = 0,5)The reference self-heating DTref shall be given.Pref ´ Rth,ambCapacitorsFor aluminium electrolytic:80 % of rated voltage at 40 °C (Uref / Urat = 0,8)For other capacitors:50 % of rated voltage at 40 °C (Uref / Urat = 0,5)–Inductors,
transformers,coils50 % of rated power at 40 °C (Pref / Prat = 0,5)Shall be givenOther electroniccomponents 3)Rated stress–Connectors and plug-insockets50 % of rated current (Iref / Irat = 0,5)–SIST EN 61709:2002



1709 ã IEC:1996- 19 -Table 2 (concluded)Type of componentReference conditions 1)Notes onself-heatingRelaysElectrical contact stress: 4)low current relays:0,5 V < U £ Urat
a.c. and 0 A < I £ 0,1 A by resistive loadgeneral purpose relays:0 V < U £ 13 V and 0,1 A < I £ Irat by resistive load and a.c.automotive relays:0 V < U £ 13 V and 0,1 A < I £ Irat
by resistive loadSwitching rate: one cycle per hour-Switches and
push-buttonsElectrical contact stress: 5)dip fix, coding switches and foil push-buttons up to rated stressswitches and push-buttons for low electrical stress:0,5 V < U £ Urat
a.c. and 0 A < I £ 0,1 A by resistive loadswitches and push-buttons for higher electrical stress:0 V < U £ 13 V and 0,1 A < I £ Irat by resistive load-Pilot and signal lamps(incandescent)Rated voltage according to specifications-1)
With typical reference self-heating DTref, the reference temperature q1 = 40 + DTref in degrees Celsiusmeans:-
for integrated circuits: the reference virtual (equivalent) junction temperature;-
for discrete semiconductors and optoelectronic components: the reference junction temperature;-
for resistors: the average reference temperature of the resistor element;-
for inductors: the average reference temperature of the winding;-
for capacitors: the reference temperature of the capacitor, where DTref = 0 °C;-
for other electronic components: the reference temperature of the component, where DTref = 0 °C.When stating the failure rates for an ambient temperature of 40 °C, the reference power dissipation Pref andthe thermal resistance Rth,amb (to the environment) for which this value holds must also be given.2)
Rectifier diodes, bridge rectifiers, Schottky diodes, thyristors, triacs and diacs.3) Varistors, PTC thermistors, NTC thermistors, surge arresters, crystal filters, quartz crystals, quartzoscillators.4)
See stress regions in 7.7.2, figure 9.5)
See stress regions in 7.8.2, figure 11.SIST EN 61709:2002



1709 ã IEC:1996- 21 -5.7 Supplementary statements5.7.1 Connectors and plug-in socketsTime period:Up to the time interval that 90 % of the components survive.Operating mode:For the electrical stress, the operating mode is continuously or intermittentlyin operating state. The components are plugged in.5.7.2 RelaysTime period:Up to the time interval that 90 % of the relays survive.Operating mode:The operating mode can be chosen within the limits set by the relay’sspecification (for coil and contact assembly).NOTE – Relay failure shall be specified in accordance with IEC 255-23.5.7.3 Pilot and signal lamps (incandescent)Time period:Up to the time interval that 90 % of the lamps survive.Operating mode:The operating mode is continuously in operating state; for
intermittentoperation the operating time is the sum of the periods alight.6 Generic stress models6.1 GeneralComponents may not always operate under the reference conditions. In such cases,operational conditions will result in failure rates different from those given for referenceconditions. Therefore, models for stress factors, by which failure rates under referenceconditions can be converted to values applying for operating conditions (actual ambienttemperature and actual electrical stress on the components), and vice versa, may be required.In clause 7 of this standard specific stress models and values for component categories aregiven and should be used for converting reference failure rates to field operational failure rates.However, if more specific models are applicable for particular component types then thesemodels should be used and their usage noted.The conversion of failure rates is only possible within the specified functional limits of thecomponents.The failure rate under operating conditions is calculated as follows:l = lref ´ pU ´ pI ´ pT(1)SIST EN 61709:2002



1709 ã IEC:1996- 23 -wherelrefis the failure rate under reference conditions;pUis the voltage dependence factor;pIis the current dependence factor;pTis the temperature dependence factor.In this model it is assumed that the failure rate under constant operating conditions is constant.Justification for use of a constant failure rate assumption should be given. This may take theform of analyses of likely failure mechanisms, related failure distributions, etc.6.2 Stress factor for voltage dependence, pUpU = exp (){}CUU1C2refC2-(2)or pU = exp ()()CUUUU3ratC2refratC2-éëêùûúìíîüýþ(3)whereUis the operating voltage in volts;Urefis the reference voltage in volts;Uratis the rated voltage in volts;C1is the constant in (1V)C2;C2 , C3are constants.The formulae given represent an empirical model to describe the voltage dependence of failurerates.NOTE – Equation (3) is obtained from equation (2) when C1
= C3 / (Urat)C2.6.3 Stress factor for current dependence, pI()()pl=-éëêùûúìíîüýþexp4ratC5refratC5CIIII(4)whereIis the operating current in amperes;Irefis the reference current in amperes;Iratis the rated current in amperes;C4 , C5are constants.The formula given represents an empirical model to describe the current dependence of failurerates.SIST EN 61709:2002



1709 ã IEC:1996- 25 -6.4 Stress factor for temperature dependence, pTpT=´´´´´´´´AAAA
e + (1-)
e e + (1-)
eEa1zE2az1Earefz2Earefz(5)with zkTTzkTT=-æèççöø÷÷=-æèççöø÷÷111
and
1110amb,ref2ref0amb,ref1
in (eV)-1whereAis a constant;Ea1, Ea2are activation energies in (eV);k0= 8,616´10-5 eV/K;Tamb,ref= 313 K;T1= (q1 + 273) in kelvins;T2= (q2 + 273) in kelvins.The temperatures q1 and q2 in degrees Celsius above mean:-for integrated circuitsq1: reference virtual (equivalent) junction temperatureq2: actual virtual (equivalent) junction temperature-for discrete semiconductors and optoelectronic componentsq1: reference junction temperatureq2: actual junction temperature-for capacitorsq1: reference capacitor temperatureq2: actual capacitor temperature-for resistorsq1: average reference temperature of the resistor element (for example, film)q2: average actual temperature of the resistor element-for inductorsq1: average reference temperature of the windingq2: average actual temperature of the winding-for other electronics componentsq1: reference ambient temperatureq2: actual ambient temperatureNOTE – Equation (5) is an empirical model and it describes the temperature dependence of the failure rates.If A = 1 and Ea2 = 0 (or A = 0, Ea1 = 0), this results in the phenomenological Arrhenius equation. The twoactivation energies (Ea1, Ea2) in the equation are used to allow for cases where two or more failuremechanisms dominate the failure process. Use of the model with two activation energies is consideredsufficient to model adequately the temperature-failure rate relation, even in cases where more than twodifferent failure mechanisms dominate the failure process. The values for A, Ea1 and Ea2 are suitablefigures that are used for calculating the nomographs. They are given in clause 7 according to the kind ofcomponent.SIST EN 61709:2002



1709 ã IEC:1996- 27 -6.5 Other factors of influenceOther stress factors are given for individual types of components in clause 7, where adependence is known (for example the effect of switching cycles for relays). At present, nogenerally applicable conversion methods can be given for the dependence of the failure rate onhumidity, air pressure, mechanical stress, and special stresses (see clause 5). If the failure ratedependence of these types of stress is known, it has to be stated. Some other factors of influ-ence could be dominant and the environmental stress may influence some componentsdifferently. If the dependence of the failure rate under these types of stress is unknown but isexpected to be a function of these types of stress, appropriate studies are necessary.NOTE – In this standard only stress factors for the operating conditional stresses (for example, current,voltage) including the ambient temperature are stated. A factor for the effect of environmental applicationconditions, also called environmental application factor, is basically not used here as in some handbooks.The setting of such a non-specific factor in this standard is not practical because the influence of theenvironmental application conditions on the component depends essentially on the design of equipment, forexample by using the equipment on ships or in the automotive field instead of in protected rooms (laboratoryconditions), no influence on the environmental application conditions will exist if the component isencapsulated in the equipment. Whether an environmental application influence occurs, and if so which one,depends therefore essentially on the equipment manufacturer. Thus, such an effect may be consideredwithin the reliability prediction of equipment using an overall environmental application factor.7 Specific stress models7.1 GeneralThe specific stress models for component categories, specified in 7.2 to 7.9, are given forconverting the failure rates between different conditions. These stress models containconstants. They are average values for the individual component types from variousmanufacturers (determined from field experience and laboratory tests).7.2 Stress factors for integrated circuits7.2.1 GeneralThe failure rate under operating conditions, from equation (1), is:l = lref x pU x pTfor digital CMOS and bipolar analogue integrated circuits(6)l = lref x pTfor all other integrated circuits (IC)(7)The stress factors for voltage and temperature dependence are specified in 7.2.2 and 7.2.3.7.2.2 Voltage dependence, factor pUThe voltage dependence is only taken into account for digital CMOS and bipolar analogueintegrated circuits, according to equation (2) or equation (3). The constants C1, C2 and C3given in table 3 are used, unless other values are stated. The results are shown in tables 4and 5.SIST EN 61709:2002



1709 ã IEC:1996- 29 -Table 3 – ConstantsIntegrated circuitUref / UratUrefC1C2C3Digital CMOS-family–5 V0,1 V–11–Analogue0,7––4,41,4Table 4 – Factor pU for digital CMOS-family ICsOperating voltageU (V)£3456789101112131415Factor pU0,80,911,11,21,31,51,61,82,02,22,52,7Table 5 – Factor pU for bipolar analogue integrated circuitsVoltage ratio U/Urat£0,30,40,50,60,70,80,91,0Factor pU0,750,770,800,871,01,31,83,07.2.3 Temperature dependence, factor pTThe relationship given in equation (5) applies only up to the rated junction temperature. Theconstants A, Ea1 and Ea2 given in table 6 are used, unless other values have been stated. Theresult is shown in figures 1 and 2.Table 6 – Constants for integrated circuitsAEa1eVEa2eVqamb,ref °CFor integrated circuits (without
EPROM, OTPROM, EEPROM,EAROM)0,90,30,740For EPROM, OPTROM, EEPROM, EAROM0,30,30,640The factor pT is obtained from figures 1 and 2 as a function of the actual virtual (equivalent)junction
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