IEC 60758:2008
(Main)Synthetic quartz crystal - Specifications and guidelines for use
Synthetic quartz crystal - Specifications and guidelines for use
IEC 60758:2008 applies to synthetic quartz single crystals intended for manufacturing piezoelectric elements for frequency control and selection. This edition includes the following significant technical changes with respect to the previous edition:
- preparation of AT-cut slice sample for etching is changed to make it easier;
- etch channel grade classification is changed considering request of the user;
- explanation of quartz axes difference between IEEE and IEC is added as Annex F.
Cristal de quartz synthétique - Spécifications et lignes directrices d'utilisation
La CEI 60758:2008 s'applique aux monocristaux de quartz synthétique destinés à être utilisés pour la fabrication d'éléments piézoélectriques pour la commande et le choix de la fréquence. La présente édition comporte les modifications techniques significatives suivantes par rapport à l'édition précédente:
- la préparation de l'échantillon de lame de coupe AT en vue de la gravure chimique a été modifiée de manière à la rendre plus facile;
- la classification en classes de canaux de corrosion a été modifiée compte tenu de la demande de l'utilisateur;
- une explication des différences relatives aux axes du quartz entre l'IEEE et la CEI a été ajoutée comme Annexe F.
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IEC 60758
Edition 4.0 2008-11
INTERNATIONAL
STANDARD
Synthetic quartz crystal – Specifications and guidelines for use
IEC 60758:2008(E)
---------------------- Page: 1 ----------------------
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IEC 60758
Edition 4.0 2008-11
INTERNATIONAL
STANDARD
Synthetic quartz crystal – Specifications and guidelines for use
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
X
ICS 31.140 ISBN 978-2-88910-286-0
® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – 60758 © IEC:2008(E)
CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Specification for as-grown synthetic quartz crystal . 11
4.1 Standard values . 11
4.1.1 Orientation of the seed. 11
4.1.2 Inclusion density . 11
4.1.3 Infrared quality indications, α , α , α . 11
3500 3585 3410
4.1.4 Frequency-versus-temperature characteristics (Figure 4 and 4.2.7). 12
4.1.5 Etch channel density ρ . 12
4.2 Requirements and measuring methods. 13
4.2.1 Orientation. 13
4.2.2 Handedness. 13
4.2.3 Synthetic quartz crystal dimensions . 13
4.2.4 Seed dimensions . 13
4.2.5 Imperfections . 13
4.2.6 Evaluation of infrared quality by alpha-measurement . 15
4.2.7 Frequency versus temperature characteristics. 17
4.2.8 Etch channel density. 18
4.3 Marking . 19
4.3.1 Shipping requirements . 19
5 Specification for lumbered synthetic quartz crystal . 20
5.1 Standard values . 20
5.1.1 Tolerance of dimensions . 20
5.1.2 Reference surface flatness . 20
5.1.3 Angular tolerance of reference surface . 20
5.1.4 Centrality of the seed. 20
5.2 Requirements and measuring methods. 20
5.2.1 As-grown quartz bars used for lumbered quartz bars . 20
5.2.2 Dimensions of lumbered synthetic quartz crystal . 20
5.2.3 Identification on reference surface . 20
5.2.4 Measurement of reference surface flatness . 20
5.2.5 Measurement of reference surface angle tolerance. 20
5.2.6 Centrality of the seed. 20
5.3 Delivery conditions. 21
5.3.1 Marking . 21
5.3.2 Packing . 21
5.3.3 Making batch . 21
6 Inspection rule for synthetic quartz crystal and lumbered synthetic quartz
crystal . 21
6.1 Inspection rule for as-grown synthetic quartz crystal . 21
6.1.1 Inspection . 21
6.1.2 Lot-by-lot test. 21
6.2 Inspection rule for lumbered synthetic quartz crystal . 22
6.2.1 Lot-by-lot test. 23
7 Guidelines for the use of synthetic quartz crystal . 23
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60758 © IEC:2008(E) – 3 –
7.1 General . 23
7.1.1 Overview . 23
7.1.2 Synthetic quartz crystal. 23
7.2 Shape and size of synthetic quartz crystal. 24
7.2.1 Crystal axis and face designation. 24
7.2.2 Seed . 24
7.2.3 Shapes and dimensions . 24
7.2.4 Growth zones . 24
7.3 Standard method for evaluating the quality of synthetic quartz crystal. 25
7.4 Other methods for checking the quality of synthetic quartz crystal . 25
7.4.1 Visual inspection . 25
7.4.2 Infrared radiation absorption method . 26
7.4.3 Miscellaneous . 26
7.5 Alpha-grade. 27
7.6 Optional grading (only as ordered), in inclusions, etch channels, Al
content. 27
7.6.1 Inclusions . 27
7.6.2 Etch channels . 27
7.6.3 Al content . 27
7.6.4 Swept quartz. 28
7.7 Ordering. 28
Annex A (informative) Frequently used sampling procedures . 38
Annex B (informative) Numerical example . 40
Annex C (informative) Example of reference sample selection . 41
Annex D (informative) Explanations of point callipers . 42
Annex E (informative) Infrared absorbance alpha value compensation . 43
Annex F (informative) The differences of the orthogonal axial system for
quartz between IEC standard and IEEE standard . 47
Bibliography . 49
Figure 1 – Idealized sections of a synthetic quartz crystal grown on a Z-cut seed . 29
Figure 2 – Quartz crystal axis and face designation . 30
Figure 3 – Typical example of cutting wafers of AT-cut plate, minor
rhombohedral-cut plate, X-cut plate, Y-cut plate and Z-cut plate. 31
Figure 4 – Frequency-temperature characteristics of the test specimen for slope . 32
Figure 5 – Quartz crystal axis and face designation . 33
Figure 6 – A synthetic quartz crystal grown on a Z-cut seed of small X-dimensions . 34
Figure 7 – An example of an early 197Os relation between the extinction
coefficient pf infra-red radiation and the Q-value of synthetic quartz . 34
Figure 8 – Lumbered synthetic quartz crystal outline and dimensions along X-, Y-
and Z-axes . 35
Figure 9 – Angular deviation for reference surface . 36
Figure 10 – Centrality of the seed with respect to the dimension along the Z- or
Z'-axis. 37
Figure D.1a – Point callipers . 42
Figure D.1b – Digital point callipers. 42
Figure E.1 – Schematic of measurement set-up . 44
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– 4 – 60758 © IEC:2008(E)
Figure E.2 – Graph relationship between averaged alpha and measured alpha at
three wave numbers of α , α and α . 46
3500 3585 3410
Figure F.1 – Left- and right-handed quartz crystals . 48
Table 1 – Inclusion densities for the grades . 11
Table 2 – Infrared quality indications for the grades . 12
Table 3 – Etch channel densities for the grades. 12
Table 4 – Test conditions and requirements for the lot-by-Iot test for group A. 22
Table 5 – Test conditions and requirements for the lot-by-lot test for group B . 22
Table 6 – Test conditions and requirements for the lot-by-lot test . 23
Table B.1 – Commodity bar sampling, method 1. 40
Table B.2 – Commodity bar sampling . 40
Table E.1 – Example of calibration data at α . 45
3585
Table E 2 – Example of calibration data at α . 45
3500
Table E 3 – Example of calibration data at α . 45
3410
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60758 © IEC:2008(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SYNTHETIC QUARTZ CRYSTAL –
SPECIFICATIONS AND GUIDELINES FOR USE
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization
comprising all national electrotechnical committees (IEC National Committees). The object of IEC is
to promote international co-operation on all questions concerning standardization in the electrical
and electronic fields. To this end and in addition to other activities, IEC publishes International
Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and
Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical
committees; any IEC National Committee interested in the subject dealt with may participate in this
preparatory work. International, governmental and non-governmental organizations liaising with the
IEC also participate in this preparation. IEC collaborates closely with the International Organization
for Standardization (ISO) in accordance with conditions determined by agreement between the two
organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has
representation from all interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC
National Committees in that sense. While all reasonable efforts are made to ensure that the
technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in
which they are used or for any misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC
Publications transparently to the maximum extent possible in their national and regional
publications. Any divergence between any IEC Publication and the corresponding national or
regional publication shall be clearly indicated in the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for
any equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual
experts and members of its technical committees and IEC National Committees for any personal
injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for
costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon,
this IEC Publication or any other IEC Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced
publications is indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the
subject of patent rights. IEC shall not be held responsible for identifying any or all such patent
rights.
International Standard IEC 60758 has been prepared by IEC technical committee 49:
Piezoelectric and dielectric devices for frequency control and selection.
This fourth edition cancels and replaces the third edition, published in 2004. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the
previous edition:
• preparation of AT-cut slice sample for etching is changed to make it easier;
• etch channel grade classification is changed considering request of the user;
• explanation of quartz axes difference between IEEE and IEC is added as Annex F.
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– 6 – 60758 © IEC:2008(E)
The text of this standard is based on the following documents:
FDIS Report on voting
49/808/FDIS 49/814/RVD
Full information on the voting for the approval of this standard can be found in the
report on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged
until the maintenance result date indicated on the IEC web site under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the
publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.
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60758 © IEC:2008(E) – 7 –
SYNTHETIC QUARTZ CRYSTAL –
SPECIFICATIONS AND GUIDELINES FOR USE
1 Scope
This International Standard applies to synthetic quartz single crystals intended for
manufacturing piezoelectric elements for frequency control and selection.
2 Normative references
The following referenced documents are indispensable for the application of this
document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
IEC 60068-1:1988, Environmental testing – Part 1: General and guidance
Amendment 1: 1992
IEC 60122-1:2002, Quartz crystal units of assessed quality – Part 1: Generic
specification
IEC 60410:1973, Sampling plans and procedures for inspection by attributes
IEC 61994 (all parts), Piezoelectric and dielectric devices for frequency control and
selection – Glossary
3 Terms and definitions
For the purposes of this document, the following terms and definitions, as well as those
given in IEC 61994, apply.
3.1
hydrothermal crystal growth
literally, crystal growth in the presence of water, elevated temperatures and pressures by
a crystal growth process believed to proceed geologically within the earth's crust. The
industrial synthetic quartz growth processes utilize alkaline water solutions confined
within autoclaves at supercritical temperatures (330 ℃ to 400 ℃) and pressures (700 to
2 000 atmospheres).
NOTE The autoclave is divided into two chambers: the dissolving chamber, containing raw quartz chips at
the higher temperature; the growing chamber, containing cut seeds at the lower temperature (see 7.1.2)
3.2
synthetic quartz crystal
single crystal of α quartz grown by the hydrothermal method. The crystal is of either
handedness and in the as-grown condition. Cultured quartz has the same meaning as
synthetic quartz crystal
3.2.1
as-grown synthetic quartz crystal
single crystal quartz grown hydrothermally. As-grown refers to the state of processing
and indicates a state prior to whatever treatment might occur after growth, excluding
quality control operations
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– 8 – 60758 © IEC:2008(E)
3.2.2
as-grown Y-bar
crystals which are produced using seed with the largest dimension in the Y-direction
3.2.3
as-grown Z-bar
crystals in which the Z-grown sector is much larger that the X-grown sector. The relative
size of the growth sector is controlled by the X-dimension of the seed
3.3
synthetic quartz crystal batch
synthetic quartz crystals grown at the same time in one autoclave
3.4
seed
rectangular parallelepiped quartz plate or bar to be used as a nucleus for crystal growth
3.5
growth zones
regions of a synthetic quartz crystal resulting from growth along different crystallographic
directions (see Figure 1)
3.6
orientation of a synthetic quartz crystal
orientation of its seed with respect to the orthogonal axes specified in 3.7
3.7
orthogonal axial system of α quartz crystal
orthogonal axis system consists of three axes with a mutually vertical X axis, Y axis, and
Z axis
3.7.1
axial system for quartz (illustrated in Figure 2)
NOTE The z-cut seed may be oriented at an angle of less than 20' to the Y-axis, in this case the axial
system becomes x, Y', z'.
3.7.2
AT-cut plate
rotated Y-cut crystal plate oriented at an angle of about +35°around the X-axis or about
−3°from the z (minor rhombohedral)-face as shown in Figure 3
3.7.3
z (minor rhombohedral)-cut plate
crystal plate parallel to the z (minor rhombohedral)-face as shown in Figure 3a
3.7.4
X-cut plate
crystal plate perpendicular to the X-axis as shown in Figure 3b
3.7.5
Y-cut plate
crystal plate perpendicular to the Y-axis as shown in Figure 3b
3.7.6
Z-cut plate
crystal plate perpendicular to the Z-axis as shown in Figure 3b
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60758 © IEC:2008(E) – 9 –
3.8
dimensions
dimensions pertaining to growth on Z-cut seed rotated less than 20°from the Y-axis
3.8.1
gross dimensions
maximum dimensions along the X-, Y-, or Y' and Z or Z' axes measured along the X-, Y'-
and Z'-axes
3.8.1.1
effective Z-dimension
as-grown effective Z dimension defined as the minimum measure in the Z (Θ=0°) or Z'
direction in usable Y or Y' area of an as-grown crystal and described by Z ,as shown in
etf
Figure 1
3.8.1.2
minimum Z-dimension
minimum distance from seed surface to Z-surface described by Z as shown in
min
Figure 1d
3.8.2
dimensions pertaining to growth on a Z-cut seed rotated more than 20°from the X･
axis
(under consideration)
3.9
inclusions
any foreign material within a synthetic quartz crystal, visible by examination of scattered
light from a bright source with the crystal immersed in a refractive index-matching liquid.
A particularly common inclusion is the mineral acmite (sodium iron silicate)
3.9.1
seed veil
array of inclusions or voids at the surface of the seed upon which a crystal has been
grown
3.9.2
etch channel
roughly cylindrical void that is present along the dislocation line after etching a quartz
crystal
3.10
do pant
any additive used in the growth process which may change the crystal habit, chemical
composition, physical or electrical properties of the synthetic quartz batch
3.11
pre-dimensioned bar
any bar whose as-grown dimensions have been altered by sawing, grinding, lapping, etc.,
to meet a particular dimensional requirement
3.12
impurity concentration
concentration of impurities relative to silicon atoms
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– 10 – 60758 © IEC:2008(E)
3.13
dislocations
linear defects in the crystal due to misplaced planes of atoms
3.14
etch channel
roughly cylindrical void present along a dislocation line after etching a test wafer
prepared from a quartz crystal
3.15
autoclave
vessel for the high-pressure high-temperature condition required for growth of a synthetic
quartz crystal
3.16
right-handed quartz or left-handed quartz
handedness of quartz crystal as determined by observing the sense of handedness of the
optical rotation in the polarized light. Right-handed quartz is the crystal of dextrorotatory
and left-handed quartz is the crystal of levorotary
3.17
twins
follow laws of crystallography relating symmetrically to specific faces or axes.
The following types have been identified in synthetic quartz crystals:
a) Electrical twins
Quartz crystal in which regions with the common Z-axis exist showing a polarity
reversal of the electrical X-axis.
b) Optical twins
Quartz crystal in which regions with the common Z-axis exhibit handedness reversal
of the optical Z-axis
3.18
infrared absorption coefficient α-value
coefficient (referred to as the α-value) established by determining the relationship
between absorption of two wavelengths: one with minimal absorption due to OH impurity,
the other with high absorption due to presence of OH impurities in the crystal lattice. The
OH impurity creates mechanical loss in resonators and its presence is correlated to the
presence of other loss-inducting impurities. The α-value is a measure of OH
concentration and is correlated with expected mechanical losses due to material
impurities. The infrared absorption coefficient α-value is determined using the following
equation:
T
1
1
α = log
t T
2
where
α is the infrared absorption coefficient;
t is the thickness of Y-cut sample, in cm ;
–1 –1
is the per cent transmission at a wave number of 3 800 cm or 3 979 cm ;
T
1
–1 –1
is the per cent transmission at a wave number of 3 410 cm , 3 500 cm , or
T
2
–1
3 585 cm .
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60758 © IEC:2008(E) – 11 –
3.19
lumbered synthetic quartz crystal
synthetic quartz crystal whose X- and Z- or Z'- surfaces in the as-grown condition have
been processed flat and parallel by sawing, grinding, lapping, etc., to meet specified
dimensions and orientation
3.19.1
lumbered Y-bar
quartz bars which are lumbered from an as-grown Y-bar
3.19.2
lumbered Z-bar
quartz bars which are lumbered from an as-grown Z-bar
3.20
reference surface
surface of the lumbered bar prepared to specific flatness and orientation with respect to
a crystallographic direction (typically the X-direction)
4 Specification for as-grown synthetic quartz crystal
4.1 Standard values
4.1.1 Orientation of the seed
Standard orientation for the seeds are Z-cuts and rotated X-cuts, minor rhombohedral
(z-minor) cut, 1°30' rotated Z-cut, 2°rotated Z-cut, 5°rotated Z-cut, and 8°30' rotated
Z-cut, the Z'-axis of the latter three seeds being rotated as shown in Figure 2.
4.1.2 Inclusion density
The inclusion density (measured as in 4.2.5.3) for each grade shall not exceed the
figures in any required size range for that grade listed in Table 1 .
Table 1 – Inclusion densities for the grades
3
Grade/size Densities per cm
Range
10-30 30-70 70-100 >100
μｍ
I a 2 1 0 0
I b 3 2 1 1
I 6 4 2 2
II 9 5 4 3
III 12 8 6 4
Users requiring a grade in only one or more of the size ranges may designate their
requirement as the grade followed by the appropriate size range.
, α , α
4.1.3 Infrared quality indications, α
3500 3585 3410
An infrared extinction coefficient value (α-value) of synthetic quartz (measured as in
4.2.6) shall be as listed under the appropriate heading for α , α , or α in
3500 3585 3410
Table 2 for the various grades:
---------------------- Page: 13 ----------------------
– 12 – 60758 © IEC:2008(E)
Table 2 – Infrared quality indications for the grades
a
Maxima Pre-1987
Grades
6
α α α
Q・10 units
3 500 3 585 3 410
Aa 0,026 0,015 0,075 3,8
A 0,033 0,024 0,082 3,0
B 0,045 0,050 0,100 2,4
C 0,060 0,069 0,114 1,8
D 0,080 0,100 0,145 1,4
E 0,120 0,160 0,190 1,0
a These Q-values were obtained from α-measurements and empirical correlation, and were in
common usage prior to 1987. These are included here as the previous labels to maintain
continuity through the change in emphasizing α-labels. α is the physical measurement now
used to control and specify quality in synthetic quartz.
The test limits above either correspond to or are unchanged (except in the cases of
grades B and D) from the α Iimits that correspond to the Q-value grades listed in
3500
the first edition of IEC 60758. This earlier publication designated some of the same
grades in terms of minimum indicated Q's in 106 units, as follows:
A = 3,0;
B = 2,2 (basis used herein), changed from 2,4 in the earlier edition;
C = 1,8;
D = 1,4 (revised);
E = 1,0 (the same as the earlier D-grade).
4.1.4 Frequency-versus-temperature characteristics (Figure 4 and 4.2.7)
The frequency-versus-temperature characteristics of synthetic quartz crystal units shall
be assessed by determination of the fractional frequency deviation measured at 15 ℃
and 35 ℃ with respect to the s
...
IEC 60758
®
Edition 4.0 2008-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Synthetic quartz crystal – Specifications and guidelines for use
Cristal de quartz synthétique – Spécifications et lignes directrices d’utilisation
IEC 60758:2008
---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED
Copyright © 2008 IEC, Geneva, Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
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International Standards for all electrical, electronic and related technologies.
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---------------------- Page: 2 ----------------------
IEC 60758
®
Edition 4.0 2008-11
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Synthetic quartz crystal – Specifications and guidelines for use
Cristal de quartz synthétique – Spécifications et lignes directrices d’utilisation
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX X
ICS 31.140 ISBN 978-2-83220-348-4
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CONTENTS
FOREWORD . 5
1 Scope . 7
2 Normative references . 7
3 Terms and definitions . 7
4 Specification for as-grown synthetic quartz crystal .11
4.1 Standard values .11
4.1.1 Orientation of the seed .11
4.1.2 Inclusion density .11
4.1.3 Infrared quality indications, α , α , α .11
3500 3585 3410
4.1.4 Frequency-versus-temperature characteristics (Figure 4 and 4.2.7).12
4.1.5 Etch channel density ρ .12
4.2 Requirements and measuring methods .13
4.2.1 Orientation .13
4.2.2 Handedness .13
4.2.3 Synthetic quartz crystal dimensions .13
4.2.4 Seed dimensions .13
4.2.5 Imperfections .13
4.2.6 Evaluation of infrared quality by alpha-measurement .15
4.2.7 Frequency versus temperature characteristics .17
4.2.8 Etch channel density .18
4.3 Marking .19
4.3.1 Shipping requirements .19
5 Specification for lumbered synthetic quartz crystal .19
5.1 Standard values .19
5.1.1 Tolerance of dimensions .19
5.1.2 Reference surface flatness .20
5.1.3 Angular tolerance of reference surface .20
5.1.4 Centrality of the seed .20
5.2 Requirements and measuring methods .20
5.2.1 As-grown quartz bars used for lumbered quartz bars .20
5.2.2 Dimensions of lumbered synthetic quartz crystal .20
5.2.3 Identification on reference surface .20
5.2.4 Measurement of reference surface flatness .20
5.2.5 Measurement of reference surface angle tolerance .20
5.2.6 Centrality of the seed .20
5.3 Delivery conditions .20
5.3.1 Marking .20
5.3.2 Packing .21
5.3.3 Making batch .21
6 Inspection rule for synthetic quartz crystal and lumbered synthetic quartz
crystal .21
6.1 Inspection rule for as-grown synthetic quartz crystal .21
6.1.1 Inspection .21
6.1.2 Lot-by-lot test .21
6.2 Inspection rule for lumbered synthetic quartz crystal .22
6.2.1 Lot-by-lot test .23
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60758 IEC:2008 – 3 –
7 Guidelines for the use of synthetic quartz crystal .23
7.1 General .23
7.1.1 Overview .23
7.1.2 Synthetic quartz crystal .23
7.2 Shape and size of synthetic quartz crystal .24
7.2.1 Crystal axis and face designation .24
7.2.2 Seed .24
7.2.3 Shapes and dimensions .24
7.2.4 Growth zones .24
7.3 Standard method for evaluating the quality of synthetic quartz crystal .25
7.4 Other methods for checking the quality of synthetic quartz crystal .25
7.4.1 Visual inspection .25
7.4.2 Infrared radiation absorption method .26
7.4.3 Miscellaneous .26
7.5 Alpha-grade .27
7.6 Optional grading (only as ordered), in inclusions, etch channels, Al
content .27
7.6.1 Inclusions .27
7.6.2 Etch channels .27
7.6.3 Al content .27
7.6.4 Swept quartz .28
7.7 Ordering .28
Annex A (informative) Frequently used sampling procedures .38
Annex B (informative) Numerical example .40
Annex C (informative) Example of reference sample selection .41
Annex D (informative) Explanations of point callipers .42
Annex E (informative) Infrared absorbance alpha value compensation .43
Annex F (informative) The differences of the orthogonal axial system for
quartz between IEC standard and IEEE standard .47
Bibliography .49
Figure 1 – Idealized sections of a synthetic quartz crystal grown on a Z-cut seed .29
Figure 2 – Quartz crystal axis and face designation .30
Figure 3 – Typical example of cutting wafers of AT-cut plate, minor
rhombohedral-cut plate, X-cut plate, Y-cut plate and Z-cut plate .31
Figure 4 – Frequency-temperature characteristics of the test specimen for slope .32
Figure 5 – Quartz crystal axis and face designation .33
Figure 6 – A synthetic quartz crystal grown on a Z-cut seed of small X-dimensions .34
Figure 7 – An example of an early 1970s relation between the extinction
coefficient pf infrared radiation and the Q-value of synthetic quartz .34
Figure 8 – Lumbered synthetic quartz crystal outline and dimensions along X-, Y-
and Z-axes .35
Figure 9 – Angular deviation for reference surface .36
Figure 10 – Centrality of the seed with respect to the dimension along the Z- or
Z'-axis.37
Figure D.1 – Point callipers .42
Figure D.2 – Digital point callipers.42
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Figure E.1 – Schematic of measurement set-up .44
Figure E.2 – Graph relationship between averaged alpha and measured alpha at
three wave numbers of α , α and α .46
3500 3585 3410
Figure F.1 – Left- and right-handed quartz crystals .48
Table 1 – Inclusion densities for the grades .11
Table 2 – Infrared quality indications for the grades .12
Table 3 – Etch channel densities for the grades .12
Table 4 – Test conditions and requirements for the lot-by-Iot test for group A .22
Table 5 – Test conditions and requirements for the lot-by-lot test for group B .22
Table 6 – Test conditions and requirements for the lot-by-lot test .23
Table B.1 – Commodity bar sampling, method 1 .40
Table B.2 – Commodity bar sampling .40
Table E.1 – Example of calibration data at α .45
3585
Table E 2 – Example of calibration data at α .45
3500
Table E 3 – Example of calibration data at α .45
3410
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60758 IEC:2008 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SYNTHETIC QUARTZ CRYSTAL –
SPECIFICATIONS AND GUIDELINES FOR USE
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization
comprising all national electrotechnical committees (IEC National Committees). The object of IEC is
to promote international co-operation on all questions concerning standardization in the electrical
and electronic fields. To this end and in addition to other activities, IEC publishes International
Standards, Technical Specifications, Technical Reports, Publicly Available Specifications (PAS) and
Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical
committees; any IEC National Committee interested in the subject dealt with may participate in this
preparatory work. International, governmental and non-governmental organizations liaising with the
IEC also participate in this preparation. IEC collaborates closely with the International Organization
for Standardization (ISO) in accordance with conditions determined by agreement between the two
organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an
international consensus of opinion on the relevant subjects since each technical committee has
representation from all interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC
National Committees in that sense. While all reasonable efforts are made to ensure that the
technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in
which they are used or for any misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC
Publications transparently to the maximum extent possible in their national and regional
publications. Any divergence between any IEC Publication and the corresponding national or
regional publication shall be clearly indicated in the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for
any equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual
experts and members of its technical committees and IEC National Committees for any personal
injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for
costs (including legal fees) and expenses arising out of the publication, use of, or reliance upon,
this IEC Publication or any other IEC Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced
publications is indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the
subject of patent rights. IEC shall not be held responsible for identifying any or all such patent
rights.
International Standard IEC 60758 has been prepared by IEC technical committee 49:
Piezoelectric and dielectric devices for frequency control and selection.
This fourth edition cancels and replaces the third edition, published in 2004. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the
previous edition:
• preparation of AT-cut slice sample for etching is changed to make it easier;
• etch channel grade classification is changed considering request of the user;
• explanation of quartz axes difference between IEEE and IEC is added as Annex F.
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This bilingual version (2012-09) corresponds to the monolingual English version,
published in 2008-11. The text of this standard is based on the following documents:
FDIS Report on voting
49/808/FDIS 49/814/RVD
Full information on the voting for the approval of this standard can be found in the
report on voting indicated in the above table.
The French version of this standard has not been voted upon. This publication has
been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged
until the maintenance result date indicated on the IEC web site under
"http://webstore.iec.ch" in the data related to the specific publication. At this date, the
publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
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60758 IEC:2008 – 7 –
SYNTHETIC QUARTZ CRYSTAL –
SPECIFICATIONS AND GUIDELINES FOR USE
1 Scope
This International Standard applies to synthetic quartz single crystals intended for
manufacturing piezoelectric elements for frequency control and selection.
2 Normative references
The following referenced documents are indispensable for the application of this
document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
IEC 60068-1:1988, Environmental testing – Part 1: General and guidance
Amendment 1: 1992
IEC 60122-1:2002, Quartz crystal units of assessed quality – Part 1: Generic
specification
IEC 60410:1973, Sampling plans and procedures for inspection by attributes
IEC 61994 (all parts), Piezoelectric and dielectric devices for frequency control and
selection – Glossary
3 Terms and definitions
For the purposes of this document, the following terms and definitions, as well as those
given in IEC 61994, apply.
3.1
hydrothermal crystal growth
literally, crystal growth in the presence of water, elevated temperatures and pressures by
a crystal growth process believed to proceed geologically within the earth's crust. The
industrial synthetic quartz growth processes utilize alkaline water solutions confined
within autoclaves at supercritical temperatures (330 ℃ to 400 ℃) and pressures (700 to
2 000 atmospheres)
NOTE The autoclave is divided into two chambers: the dissolving chamber, containing raw quartz chips at
the higher temperature; the growing chamber, containing cut seeds at the lower temperature (see 7.1.2).
3.2
synthetic quartz crystal
single crystal of α quartz grown by the hydrothermal method. The crystal is of either
handedness and in the as-grown condition. Cultured quartz has the same meaning as
synthetic quartz crystal
3.2.1
as-grown synthetic quartz crystal
single crystal quartz grown hydrothermally. As-grown refers to the state of processing
and indicates a state prior to whatever treatment might occur after growth, excluding
quality control operations
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3.2.2
as-grown Y-bar
crystals which are produced using seed with the largest dimension in the Y-direction
3.2.3
as-grown Z-bar
crystals in which the Z-grown sector is much larger that the X-grown sector. The relative
size of the growth sector is controlled by the X-dimension of the seed
3.3
synthetic quartz crystal batch
synthetic quartz crystals grown at the same time in one autoclave
3.4
seed
rectangular parallelepiped quartz plate or bar to be used as a nucleus for crystal growth
3.5
growth zones
regions of a synthetic quartz crystal resulting from growth along different crystallographic
directions (see Figure 1)
3.6
orientation of a synthetic quartz crystal
orientation of its seed with respect to the orthogonal axes specified in 3.7
3.7
orthogonal axial system of α quartz crystal
orthogonal axis system consists of three axes with a mutually vertical X axis, Y axis, and
Z axis
3.7.1
axial system for quartz (illustrated in Figure 2)
NOTE The z-cut seed may be oriented at an angle of less than 20' to the Y-axis, in this case the axial
system becomes x, Y', z'.
3.7.2
AT-cut plate
rotated Y-cut crystal plate oriented at an angle of about +35°around the X-axis or about
−3°from the z (minor rhombohedral)-face as shown in Figure 3
3.7.3
z (minor rhombohedral)-cut plate
crystal plate parallel to the z (minor rhombohedral)-face as shown in Figure 3a
3.7.4
X-cut plate
crystal plate perpendicular to the X-axis as shown in Figure 3b
3.7.5
Y-cut plate
crystal plate perpendicular to the Y-axis as shown in Figure 3b
3.7.6
Z-cut plate
crystal plate perpendicular to the Z-axis as shown in Figure 3b
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60758 IEC:2008 – 9 –
3.8
dimensions
dimensions pertaining to growth on Z-cut seed rotated less than 20°from the Y-axis
3.8.1
gross dimensions
maximum dimensions along the X-, Y-, or Y' and Z or Z' axes measured along the X-, Y'-
and Z'-axes
3.8.1.1
effective Z-dimension
as-grown effective Z dimension defined as the minimum measure in the Z (Θ=0°) or Z'
direction in usable Y or Y' area of an as-grown crystal and described by Z ,as shown in
etf
Figure 1
3.8.1.2
minimum Z-dimension
minimum distance from seed surface to Z-surface described by Z as shown in
min
Figure 1d
3.8.2
dimensions pertaining to growth on a Z-cut seed rotated more than 20°from the X･
axis
(under consideration)
3.9
inclusions
any foreign material within a synthetic quartz crystal, visible by examination of scattered
light from a bright source with the crystal immersed in a refractive index-matching liquid.
A particularly common inclusion is the mineral acmite (sodium iron silicate)
3.9.1
seed veil
array of inclusions or voids at the surface of the seed upon which a crystal has been
grown
3.9.2
etch channel
roughly cylindrical void that is present along the dislocation line after etching a quartz
crystal
3.10
dopant
any additive used in the growth process which may change the crystal habit, chemical
composition, physical or electrical properties of the synthetic quartz batch
3.11
pre-dimensioned bar
any bar whose as-grown dimensions have been altered by sawing, grinding, lapping, etc.,
to meet a particular dimensional requirement
3.12
impurity concentration
concentration of impurities relative to silicon atoms
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3.13
dislocations
linear defects in the crystal due to misplaced planes of atoms
3.14
etch channel
roughly cylindrical void present along a dislocation line after etching a test wafer
prepared from a quartz crystal
3.15
autoclave
vessel for the high-pressure high-temperature condition required for growth of a synthetic
quartz crystal
3.16
right-handed quartz or left-handed quartz
handedness of quartz crystal as determined by observing the sense of handedness of the
optical rotation in the polarized light. Right-handed quartz is the crystal of dextrorotatory
and left-handed quartz is the crystal of levorotary
3.17
twins
follow laws of crystallography relating symmetrically to specific faces or axes.
The following types have been identified in synthetic quartz crystals:
a) Electrical twins
Quartz crystal in which regions with the common Z-axis exist showing a polarity
reversal of the electrical X-axis.
b) Optical twins
Quartz crystal in which regions with the common Z-axis exhibit handedness reversal
of the optical Z-axis
3.18
infrared absorption coefficient α-value
coefficient (referred to as the α -value) established by determining the relationship
between absorption of two wavelengths: one with minimal absorption due to OH impurity,
the other with high absorption due to presence of OH impurities in the crystal lattice. The
OH impurity creates mechanical loss in resonators and its presence is correlated to the
presence of other loss-inducting impurities. Theα -value is a measure of OH
concentration and is correlated with expected mechanical losses due to material
impurities. The infrared absorption coefficient α-value is determined using the following
equation:
T
1
1
α= log
t T
2
where
α is the infrared absorption coefficient;
t is the thickness of Y-cut sample, in cm ;
–1 –1
is the per cent transmission at a wave number of 3 800 cm or 3 979 cm ;
T
1
–1 –1
is the per cent transmission at a wave number of 3 410 cm , 3 500 cm , or
T
2
–1
3 585 cm .
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60758 IEC:2008 – 11 –
3.19
lumbered synthetic quartz crystal
synthetic quartz crystal whose X- and Z- or Z'- surfaces in the as-grown condition have
been processed flat and parallel by sawing, grinding, lapping, etc., to meet specified
dimensions and orientation
3.19.1
lumbered Y-bar
quartz bars which are lumbered from an as-grown Y-bar
3.19.2
lumbered Z-bar
qu
...
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