EN 60444-6:1997

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Measurement of quartz crystal unit parameters - Part 6: Measurement of drive level dependence (DLD) (IEC 60444-6:1995)Messung von Schwingquarz-Kennwerten -- Teil 6: Messung der Belastungsabhängigkeit (DLD)Mesure des paramètres des résonateurs à quartz -- Partie 6: Mesure de la dépendance du niveau d'excitation (DNE)Measurement of quartz crystal unit parameters -- Part 6: Measurement of drive level dependence (DLD)31.140Piezoelectric and dielectric devicesICS:Ta slovenski standard je istoveten z:EN 60444-6:1997SIST EN 60444-6:2002en01-september-2002SIST EN 60444-6:2002SLOVENSKI
STANDARD
NORMECEIINTERNATIONALEIECINTERNATIONAL444-6STANDARDPremière éditionFirst edition1995-01Mesure des paramètres des résonateursà quartzPartie 6:Mesure de la dépendance du niveaud'excitation (DNE)Measurement of quartz crystal unit parameters —Part 6:Measurement of drive level dependence (DLD)© CEI 1995 Droits de reproduction réservés — Copyright – all rights reservedAucune partie de cette publication ne peut étre reproduite niutilisée sous quelque forme que ce soit et par aucun pro-cédé, électronique ou mécanique, y compris la photocopie etles microfilms, sans l'accord écrit de l'éditeur.No part of this publication may be reproduced or utilized inany form or by any means, electronic or mechanical,including photocopying and microfilm, without permissionin writing from the publisher.Bureau Central de la Commission Electrotechnique Internationale 3, rue de Varembé Genève, SuisseCommission Electrotechnique Internationale CODE PRIXInternational Electrotechnical Commission PRICE CODEMetnayHapoAHae 3netcsparexHH4ecitafi KoMHCCawPour prix, voir catalogue en vigueurFor price, see current catalogueIEC•QSIST EN 60444-6:2002

444-6 © IEC:1995- 3 -CONTENTSPageFOREWORD 5INTRODUCTION 9Clause1General
111.1Scope 111.2 Normative references
112DLD effects 112.1Reversible changes in frequency and resistance
112.2 Irreversible changes in frequency and resistance
112.3 Causes of DLD effects 13Drive levels for DLD measurement
134 Test methods
154.1 Test method A (7r-network method)
154.2 Test method B (oscillator method) 19Annex A - Relationship between electrical drive level and mechanical displacement ofquartz crystal units 31SIST EN 60444-6:2002

444-6 © IEC:1995- 5 -INTERNATIONAL ELECTROTECHNICAL COMMISSIONMEASUREMENT OF QUARTZ CRYSTAL UNIT PARAMETERS —Part 6: Measurement of drive level dependence (DLD)FOREWORD1)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 cooperation on all questions concerning standardization in the electrical andelectronic fields. To this end and in addition to other activities, the IEC publishes International Standards.Their preparation is entrusted to technical committees; any IEC National Committee interested inthe subject dealt with may participate in this preparatory work. International, governmental andnon-governmental organizations liaising with the IEC also participate in this preparation. The IECcollaborates closely with the International Organization for Standardization (ISO) in accordance withconditions determined by agreement between the two organizations.2)The formal decisions or agreements of the IEC on technical matters, prepared by technical committees onwhich all the National Committees having a special interest therein are represented, express, as nearly aspossible, an international consensus of opinion on the subjects dealt with.3)They have the form of recommendations for international use published in the form of standards, technicalreports or guides and they are accepted by the National Committees in that sense.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.International Standard IEC 444-6 has been prepared by IEC technical committee 49:Piezoelectric and dielectric devices for frequency control and selection.It forms part 6 of a series of publications dealing with the measurement of quartz crystalunit parameters.Part 1: Basic method for the measurement of resonance frequency and resonance resist-ance of quartz crystal units by zero phase technique in a it-network, is issued as IEC 444-1(second edition, 1986).Part 2: Phase offset method for measurement of motional capacitance of quartz crystalunits, is issued as IEC 444-2 (1980).Part 3: Basic method for the measurement of two-terminal parameters of quartz crystalunits up to 200 MHz by phase technique in a It-network with compensation of the parallelcapacitance Co, is issued as IEC 444-3 (1986).Part 4: Method for the measurement of the load resonance frequency fL, load resonanceresistance R the calculation of other derived values of quartz crystal units, up to30 MHz, is issued as IEC 444-4 (1988).SIST EN 60444-6:2002

444-6 © IEC:1995- 7 -Part 5: Reference method of the measurement of crystal units, using automatic networkanalyzer techniques for the determination of equivalent electrical parameters, will beissued as IEC 444-5.The text of this standard is based on the following documents:DISReport on voting
49(CO)27349/284/RVDFull information on the voting for the approval of this standard can be found in the reporton voting indicated in the above table.Annex A forms an integral part of this standard.SIST EN 60444-6:2002

444-6 © IEC:1995- 9 -INTRODUCTIONThe drive level (expressed as power/voltage across or current through the crystal unit)forces the resonator to produce mechanical oscillations by way of piezoelectric effect. Inthis process, the acceleration work is converted to kinetic and elastic energy and thepower loss to heat. The latter conversion is due to the inner and outer friction of the quartzresonator.The frictional losses depend on the velocity of the vibrating masses and increase when theoscillation is no longer linear or when critical velocities, elongations or strains, excursionsor accelerations are attained in the quartz resonator or at its surfaces and mounting points(see annex A). This causes changes in resistance and frequency, as well as furtherchanges due to the temperature dependence of these parameters.At "high" drive levels (e.g. above 1 mW or 1 mA for AT-cut crystal units) changes areobserved by all crystal units and these also can result in irreversible amplitude andfrequency changes. Any further increase of the drive level may destroy the resonator.Apart from this effect, changes in frequency and resistance are observed at low" drivelevels in some crystal units, e.g. below 1 pW or 50 pA for AT-cut crystal units). In thiscase, if the loop gain is not sufficient, the start-up of the oscillation is difficult. In crystalfilters the transducer attenuation and ripple will change.Furthermore, the coupling between a specified mode of vibration and other modes (e.g. ofthe resonator itself, the mounting and the back-fill gas) also depends on the level of drive.Due to the differing temperature response of these modes, these couplings give rise tochanges of frequency and resistance of the specified mode within narrow temperatureranges. These changes increase with increasing drive level. However, this effect will notbe considered further in this part of IEC 444.SIST EN 60444-6:2002

444-6 ©IEC:1995– 11 -MEASUREMENT OF QUARTZ CRYSTAL UNIT PARAMETERS –Part 6: Measurement of drive level dependence (DLD)1 General1.1 ScopeThis part of IEC 444 applies to the measurements of drive level dependence (DLD) ofquartz crystal units. Two test methods are described. Method A, based on the it-networkmethod according to IEC 444-1, can be used in the complete frequency range covered bythis part of IEC 444. Method B, an oscillator method, is suitable for measurements offundamental mode crystal units in larger quantities with fixed conditions.1.2 Normative referencesThe following normative documents contain provisions which, through reference in thistext, constitute provisions of this part of IEC 444. At the time of publication, the editionsindicated were valid. All normative documents are subject to revision, and parties toagreements based on this part of IEC 444 are encouraged to investigate the possibility ofapplying the most recent editions of the normative documents indicated below. Membersof IEC and ISO maintain registers of currently valid International Standards.IEC 444: Measurement of quartz crystal unit parametersIEC 444-1:1986, Measurement of quartz crystal unit parameters by zero phase techniquein a n-network - Part 1: Basic method for the measurement of resonance frequency andresonance resistance of quartz crystal units by zero phase technique in a re-network2 DLD effects2.1 Reversible changes in frequency and resistanceReversible changes are changes in frequency and resistance occurring under the samedrive levels after repeated measurements made alternatively at low and high levels, orafter continuous or quasi-continuous measurements from the lowest to the highest leveland back, if these changes remain within the limits of the measurement accuracy.2.2 Irreversible changes in frequency and resistanceIrreversible changes are significant changes in frequency and/or resistance occurring atlow level after an intermediate measurement at high level, e.g. when a previously highresistance at low level has changed in the repeated measurement to a low resistance.NOTE — When the crystal unit has not been operated for several days, its resistance may have changedback to a high value when operated again at a lower level. Greater attention should be paid to the irreversibleeffect since it can significantly impair the performance of devices which are operated only sporadically.SIST EN 60444-6:2002

444-6©IEC:1995- 13 -2.3 Causes of DLD effectsWhereas the mostly reversible effects are due to excessive crystal drive level, the irrevers-ible effects are due to production, especially to imperfect production techniques. Examplesof causes are:-particles on the resonator surface (partly bound by oils, cleaning agents, solvents orbound electrostatically);-mechanical damage of the resonator (e.g. fissures due to excessively coarselapping abrasive which may increase in size);-gas and oil inclusions in the electrodes (e.g. due to a poor vacuum or an inadequatecoating rate during evaporation);-poor contacting of the electrodes at the mounting (e.g. the conductive adhesive hasan inadequate metal component, was insufficiently baked out or was overheated; alsoexcessive contact resistance between the conductive adhesive and the electrodes ormounting);-mechanical stresses between mounting, electrodes and quartz element.3 Drive levels for DLD measurementFor the DLD measurement, a low and a high level of drive (and possibly further levels) areapplied. The high level is the nominal drive level which should be equal to the level in theapplication at its steady state.It should be noted that this level shall be below the maximum applicable level which isderived in annex A. If not specified, a standard value for the crystal current of 1 mA, corre-sponding to the velocity vmax = 0,2 m/s for AT-cut crystal units, shall be used. The drivelevel in watts is then calculated with the mean value of the specified maximum and mini-mum resistances.The minimum drive level occurring at the start-up of an oscillator can be determined onlyin a few cases by active or passive measuring methods due to the noise limits of themeasuring instruments (for measurements according to IEC 444-1, at approximately 1 nWor 10 pA).A velocity vmax = 0,01 m/s, corresponding to 50 IA for AT-cut crystals, has proved to be apractical value for ic-network measurements (see method A).In the following, two methods of DLD measurement are described.Method A is based on the ic-network method according to IEC 444-1, which can be used inthe complete frequency range covered by this standard. It allows the fast selection of drivelevel sensitive quartz crystal units by a sequence of three measurements. The allowedvariation of the resonance resistances given in figure 1 is based on long-termexaminations of crystal units of different manufacturers and proved to be a reliableindicator for crystal units showing start-up problems. If necessary, this method could alsobe extended by measuring a large number of different drive levels. However, in practice,this is not necessary in most cases (see 4.1 b).SIST EN 60444-6:2002

444-6 © I EC:1995- 15 -Method B is an oscillator method which is especially suitable for measuring fundamentalmode crystal units in larger quantities with fixed measurement conditions (maximum drivelevel, Rr max) in an economical way.If the proposed measurement techniques are not sufficient in special cases, the usershould make available an original oscillator with slightly reduced feedback or an originalfilter.Recommendation: Both methods can be used for all types of crystals, however:-method A is recommended for filter crystals and comparative measurements;-method B is recommended for oscillator crystals and for go/no-go measurements.4 Test methods4.1 Test method A (r-network method)a) Testing at two drive levelsTesting is performed at low and high drive levels as described in clause 3 with measure-ments of frequency and a resonance resistance according to IEC 444-1. The tolerancesare ±10 % for the levels of current and ±20 % for those of power.1) Storage for at least one day at 105 °C and after that at least 2 h at roomtemperature or storage for one week at room temperature.2)Measurement at low drive level (50 pA):3)Measurement at high drive level (1 mA):4)Measurement at low drive level (50 pA):fr = fr1'fr = fr2'fr = fr3'Rr = R11' 'Fir= Rr2'Rr = Rr3'5)Calculation of y12 = Rr1/Rr2. The value of y12 shall be smaller than the maximumvalue of 'y given by the line drawn in figure 1 (abscissa = Rr2).The tolerable frequency change I fr2 - fr., I shall be 5 x 10-6 x fr.,, unless otherwisespecified in the detail specification.6)Calculation of y13 =The The value of y13 shall be smaller than (y + 1)/2,r1/R where the value of y is taken from figure 1 (abscissa = Rr3).The tolerable frequency change I fr3 - fr1 I shall be 2,5 x 10-6 x fr. , unless otherwisespecified in the detail specification.b) Testing according to specificationTesting is performed at low to high drive levels and back again to low level asdescribed in a). These and, if necessary, further levels with their tolerances, thepermissible deviations of the frequency and resist
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