IEC 60758:2008

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.

General Information

• Status: Published
• Publication Date: 12-Nov-2008
• ICS: 31.140 - Piezoelectric devices
• Technical Committee: TC 49 - Piezoelectric, dielectric and electrostatic devices and associated materials for frequency control, selection and detection
• Drafting Committee: WG 5 - TC 49/WG 5
• Current Stage: DELPUB - Deleted Publication
• Start Date: 18-May-2016
• Completion Date: 26-Oct-2025

Relations

• Revises: IEC 60758:2004 - Synthetic quartz crystal - Specifications and guide to the use
• Effective Date: 05-Sep-2023
• Revised: IEC 60758:2016 - Synthetic quartz crystal - Specifications and guidelines for use
• Effective Date: 05-Sep-2023

Overview - IEC 60758:2008 (Synthetic quartz crystal)

IEC 60758:2008 specifies the requirements and guidelines for synthetic quartz single crystals used to manufacture piezoelectric elements for frequency control and selection (crystal resonators, oscillators, filters). The fourth edition (2008) updates test and grading procedures and adds practical guidance-most notably easier preparation of AT‑cut slice samples for etching, revised etch‑channel grade classification, and an informative Annex (F) explaining the differences between IEEE and IEC quartz axis conventions.

Key topics and technical requirements

• Scope and terms: Applies to hydrothermally grown synthetic quartz single crystals intended for piezoelectric devices. Normative references include relevant IEC standards on sampling, environmental testing and crystal units.
• Specifications for as‑grown quartz: Orientation (seed axis), inclusion density, infrared‑quality (alpha) indications, frequency‑vs‑temperature characteristics and etch‑channel density.
• Measuring methods: Procedures for orientation, handedness, dimensions, imperfections, infrared alpha measurements and etch channel evaluation.
• Lumbered (processed) quartz: Dimensional tolerances, reference surface flatness and angular tolerances, seed centrality, marking, packing and delivery conditions.
• Inspection and sampling rules: Lot‑by‑lot test requirements, inspection procedures and informative sampling annexes.
• Guidelines for use: Recommendations on crystal shapes/sizes, face designations (cuts such as AT‑cut, X/Y/Z cuts), growth zones, wafer cutting, quality evaluation methods (visual, IR absorption alpha measurement), alpha‑grading and optional grading for inclusions, etch channels and aluminium content.
• Informative annexes: Examples of sampling, calibration, measurement set-ups and the IEEE vs IEC axis differences (Annex F).

Practical applications and users

IEC 60758 is essential for:

• Crystal manufacturers - to specify and certify synthetic quartz raw material for piezoelectric elements.
• Component and oscillator designers - to select appropriate quartz grades (alpha grade, etch‑channel classification, frequency‑temperature behavior) for stable frequency control.
• Quality and test laboratories - to apply standardized measurement and lot‑by‑lot inspection procedures.
• Procurement and supply chain - for contract specifications, marking, packing and acceptance testing of quartz bars and wafers.

Using IEC 60758 helps ensure repeatable frequency stability, low defect rates and reliable production of quartz resonators and frequency control components.

Related standards

• IEC 60068‑1 - Environmental testing guidance
• IEC 60122‑1 - Quartz crystal units of assessed quality
• IEC 60410 - Sampling plans and procedures
• IEC 61994 - Glossary for piezoelectric and dielectric frequency devices

Keywords: IEC 60758, synthetic quartz crystal, piezoelectric elements, frequency control, AT‑cut, etch channel, alpha measurement, quartz specifications.

Standards Content (Sample)

IEC 60758
Edition 4.0 2008-11
INTERNATIONAL
STANDARD
Synthetic quartz crystal – Specifications and guidelines for use

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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
– 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

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

– 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
Table E 2 – Example of calibration data at α . 45
Table E 3 – Example of calibration data at α . 45
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
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for Standardization (ISO) in accordance with conditions determined by agreement between the two
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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.

– 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.

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
– 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

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

– 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
α = log
t T
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
is the per cent transmission at a wave number of 3 410 cm , 3 500 cm , or
T
–1
3 585 cm .
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
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:

– 12 – 60758 © IEC:2008(E)
Table 2 – Infrared quality indications for the grades
a
Maxima Pre-1987
Grades
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
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 series resonance frequency at 25 ℃. The fractional
deviation shall satisfy the following:
–6
－ fractional frequency deviation at 15 ℃: +0,5 to +1,5 × 10 ;
–6
－ fractional frequency deviation at 35 ℃: –0,5 to –1,5 × 10 .
Measurement shall be made in accordance with 4.7.3 of IEC 60122-1 .
4.1.5 Etch channel density ρ
When required, the etch channel density, ρ, per cm (measured as in 4.2.8) for each
grade, shall comply with the listings in Table 3.
Table 3 – Etch channel densities for the grades
Grade Maximum number ρ per cm
1aa 2
1a 5
1 10
2 30
3 100
4 300
60758 © IEC:2008(E) – 13 –
4.2 Requirements and measuring methods
4.2.1 Orientation
The orientation of the seed shall be along specified directions, with a deviation of less
than 30 min from nominal.
4.2.2 Handedness
The handedness of the seed shall be specified, either right-hand or left-hand (see
Figure 2).
4.2.3 Synthetic quartz crystal dimensions
The dimension shall be measured by callipers or point callipers which enable the hollow
point of a synthetic quartz crystal to be measured (see Annex D).
4.2.3.1 Dimension along Y or Y'- axis
The dimension shall be as specified (see Figure 1d).
4.2.3.2 Dimension along Z or Z'-axis dimension shall be measured by a neck
ipers
The dimension along the Z or Z'-axis shall be specified as the maximum dimension along
the Z or Z'-axis in the greater X zone (see Figure 1c).
4.2.3.3 Dimension Z or Z'
eff etf
The Z or Z' dimension shall be specified as the minimum dimension along the Z or
eff eff
Z'-axis (see Figure 1c).
4.2.3.4 Dimension Z or Z'
mln min
The dimension shall be as specified (see Figures 1c and 1d).
4.2.3.5 Dimension along X-axis
The gross dimension along the X-axis shall be as specified (see Figure 1c).
4.2.4 Seed dimensions
4.2.4.1 Z or Z' dimension
The Z or Z'-dimension (i.e. thickness) of the Z-cut or rotated Z-cut seed shall be less
than 3 mm, unless otherwise specified.
4.2.4.2 X-dimension
The dimension X of the seed shall be as specified.
4.2.5 Imperfections
4.2.5.1 Twinning
There shall be no electrical or optical twinning in the usable region. The existence of
twinning shall be checked by visual inspection.

– 14 – 60758 © IEC:2008(E)
4.2.5.2 Cracks and fractures
There shall be no cracks or fractures in the usable region. The existence of cracks and
fractures shall be checked by visual inspection.
4.2.5.3 Inclusion density
The following two measuring methods are used and either one may be chosen.
Method 1
Inclusions within stated ranges are counted visually per cm in sample volumes within a
crystal using a stereo binocular microscope operating at 30 × to 40 ×magnification
equipped for counting within either a circular or a square field and with a calibrated
reticule scale for determining particle sizes, intense side illumination (such as halogen
lamps) over a recessed black matt background, an index matching liquid (n = 1,55,
approximately) for transparency, and means of measuring the dimensions of the sample
volumes counted.
Method 2
In case it is difficult to apply method 1, crystals are compared with reference samples
appropriately representing each grade range, immersing within an index matching liquid
(n = 1,55 approximately) for transparency, or applying such liquid to the surface. The
reference samples shall be agreed upon between the supplier and the user. An example
for the reference sample selection procedure is given in Annex C.
4.2.5.3.1 Sampling
Because of the considerable costs in time, labour and money, some plan for sampling
both bars and regions within the bars is normally used by agreement between the
supplier and the buyer when quality control of either inclusion density or etch channel
density is required.
Clearly, the preferable low-cost inspection situation is the one in which the densities of
inclusions or etch channels are well below the test limits, and infrequent samples can be
justified. Since such situations are not always attainable, more rigorous inspection
strategies will sometimes be required for appropriate density control, and shall be found,
worked out, and agreed upon between the supplier and the user.
Sound statistical methods are required in order to meet appropriate agreed-upon assured
quality level tests and ensure that the crystals and the volumes counted within them are
sufficiently representative. Since sampling procedures and statistical confidence tests
are described in the literature, their principles will not be repeated here.
4.2.5.3.2 Batch sampling
In most batch sampling, a suitable sample bar or group of bars is chosen to represent
the batch population. The number of bars shall depend on the number in the batch, the
type of crystal, the intended application, the separation between the mean and the target
inclusion densities and the AQL confidence level requirement needed to provide
sufficient assurance that the batch inclusion density in each size range shall be below
their applicable grade test limits. The sample bar group shall reasonably represent the
batch with respect to inclusion densities. Deviations, if any, are allowed and shall be
towards higher, not lower, inclusion densities for safe assurance.

60758 © IEC:2008(E) – 15 –
4.2.5.3.3 Volumes within a bar
A group of volumes within each sample bar is next chosen for inclusion counting. The
boundaries of the volumes are defined by the area of the focal field of the microscope (or
the outline of a square reticule) and either the height of the bar or the length range of the
depth adjustment of the microscope chosen for use. It is necessary to determine and
total the volumes throughout which counts are accumulated. The volumes selected for
counting should include mainly regions (usually Z-growth zones as in Figure 3) whose
material will be present and active in the finished devices and should not avoid dense
inclusion volumes within these regions. The number of volumes per bar shall be at least
six or more for reasonable statistical confidence.
The sample volume locations within a bar shall be appropriately distributed in its X-, Y-,
Z-axes to include the variations of the inclusion density with these independent variables.
Typical synthetic quartz bars (Figure 3a) are long in the Y- and small in the X- and
Z-axes dimensions. Normally, the greatest variation of inclusion density appears over a
zone's grown direction, for example the Z-dimension in the Z-zone (Figures 1a and 3).
Thus, for large Z-crystals, the sampled regions shall be located at varied Z-distances
from the seed to ensure that the bar's range of Z is well-represented by the group of
sample volumes. Similarly, any noted variations over Y or X shall be sampled, if such
variations are present.
To aid in distributing sample volumes within a typical bar, its lesser X-surface is marked
with transverse Z'-lines, perpendicular to the seed at regular 10 mm intervals over the
Y-length of the surface. Sample volumes for inclusion counting are chosen as needed
from within each rectangle formed by the marks and the crystal surfaces. To locate the
sample volumes at varied distances from the seed, in small crystals (where a Z-zone
measures less than double the field diameter of the microscope), they should be
alternated near and far from the seed. For larger crystals, the volumes should be
sequenced in Z over its range to ensure that each inclusion band is represented in the
sample volumes. Several frequently used sampling plans are illustrated in Annex A.
4.2.5.3.4 Inclusion counting
The circular or square field of view chosen for counting within its marked rectangle is
scanned vertically over its chosen X-height within the microscope's range of depth
adjustment, as follows.
If the sample is a Y-bar with a relatively small X-height, the scans will be at a series of
sites varied in Z along its length (under side illumination, with its lesser X-surface up).
Beginning in a rectangle positioned at one end of the usable zone, an inclusion count is
taken in an X-cylinder (or parallelelipiped) volume. Starting slightly below the lesser
X-surface (and not counting surface material), all visible inclusions in focus are
categorized and counted in each of the size categories required by the customer's order:
10 μm to 30 μm, 30 μm to 70 μm, 70 μm to 100 μm, and greater than 100 μm. The
microscope is then lowered and the newly focused inclusions counted and added into
their size categories. This process is continued through the chosen X-height; the
procedure is repeated at the next sample position, and so on.
The counts from the bar's sample sites in each of the four size categories are summed
by category and divided by the calculated total of the sampled volumes, to obtain an
for each category in one bar. The count averages in each
average count per cm
category from all the sample bars from a run are averaged and recorded as required to
represent the size distribution for the run. Maximum and minimum bar averages may also
be recorded, if desired or required. A numerical example is given in Annex B.
4.2.6 Evaluation of infrared quality by alpha-measurement
The infrared absorption per centimetre at one or more of 3 410, 3 500 or 3 585 wave
numbers is measured in a Y-cut slice scan as the difference between the absorption at

– 16 – 60758 © IEC:2008(E)
the chosen wave number and absorption in the background outside the band, at
–1 –1
3 800 cm or at 3 979 cm when using a single beam instrument. Since α are known
to vary directly with the total Z-growth size distribution of the crystals in one batch, a
user may designate his preference in the batch distribution for sample testing. Such
choices are often either an average Z-crystal or a maximum Z-crystal (for worst-case
maximum alpha-measurement).
The following two measuring methods are used and either one shall be chosen.
Method 1
The wave number is fixed and the positional transmission data are measured by
scanning the sample.
Method 2
The sample is fixed and the transmission data are measured at chosen wave numbers on
several points in the sample.
4.2.6.1 Preparation of the Y cut slice
The synthetic quartz crystal to be sampled is mounted on a substrate then sliced with a
quartz saw to yield at least one Y-cut slice whose thickness after lapping and polishing
will fall in the range of 5 mm to 10 mm. The 5 mm thickness is appropriate for high α
-material, to resolve its α -variations; the mid-range for medium α; and the 10 mm
thickness is appropriate for the lowest α-material to measure its small absorption.
After sawing, the slice is lapped on both major surfaces: first, with a homogenized
mixture of 25 μm abrasive; second, with a homogenized mixture of 3 μm abrasive.
Further lapping to polish is optional and is preferred for low α.
4.2.6.2 Calibration of a standard Y-cut slice in an infrared spectrophotometer
The infra-red spectrophotometer is turned on, allowed to warm and fully stabilize, then
calibrated. The normal daily calibration includes its transmission (0 % - 100 %) or
absorbance (log T =1,0 - 0) limit settings, chart speed and synchronized sample
scanning arrangement. For evaluation and normal use, a 1,5 mm width aperture is
located in the sample beam. For the lowest α-value measurements, a 5 mm width
aperture may be required. The aperture's height shall not exceed the X-dimension of the
seed or 5,0 mm. A polished Y-cut standard reference slice is placed first in the sample
holder, which is then mounted in the scanning device.
The wave number control is set at a background setting (outside, but near the OH
–1
absorption band), usually 3 800 ± 3 cm , and the sample is translated through the beam
with synchronized chart advance at the fixed wave number. Such scanning is done only
in the Z-growth zones of the Y-cut slice (illustrated in Figures 1 and 3). In certain cases
where background noise may be a problem, such as single beam operation, a higher
–1
background wave number 3 979 ± 3 cm may be used for lowered background noise. If
the background scan trace is not reasonably flat outside the original seed's boundaries, a
thin film of fluorolube grease shall be applied to both major surfaces of the semi-polished
Y-cut slice. Baseline changes shall not exceed 0,02 absorption units during a
background scan. After the sample has completed a successful scan at background, the
–1
wave number is adjusted to the chosen 3 410, 3 500 or 3 585 ± 3 cm . The sample is
returned to its original position and the chart paper rerolled to the position where its
wave number scan began. The sample is then scanned to plot its infra-red absorption at
this wave number in the absorption band.

60758 © IEC:2008(E) – 17 –
The calibration α-values (maximum and minimum) are calculated from this reference
scan, using the equation:
** *
A − A
α =
Y− cut slice thickness in centimetres
where
A* is the chosen value of 3 800 and 3 979;
A** is the chosen value of 3 410 3 500 and 3 585
NOTE A is the logarithm (base 10) of the traction of the incident beam absorbed by the sample at the
subscript wave number.
The spectrophotometer is considered in proper calibration if its α and α readings
max min
are repeatable within ±0,004 units of the standard's values for them. A standardization
correction may be calculated as needed to bring the instrument's reading on a standard
slice to an accepted value and used while current.
4.2.6.3 Test measurement of a Y-cut slice
After successful calibration, each prepared (preferably polished) unknown slice is
scanned at the background and chosen OH absorption band wave numbers, using a thin
film of oil as needed in cases where there is only a semi-polish. Their pertinent α-values
are calculated using the equation above. Regions excluded from this determination are
±2,0 mm from the seed centre and the excess growth beyond the appropriate
pre-dimensioned bar dimensions.
4.2.6.4 Compensation of alpha value by standard sample
Correlation between the test equipment of each manufacturer cannot be assured by strict
adherence to uniform measuring conditions and procedures. Therefore, it is necessary to
establish a compensation value for α. The recommended compensation value is
determined by each manufacturer referencing the procedure described in Annex E.
4.2.7 Frequency versus temperature characteristics
The specifications for the quartz crystal unit for evaluating the
frequency-versus-temperature characteristics shall be as follows, and meas
...

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

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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

– 2 – 60758  IEC:2008
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

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

– 4 – 60758  IEC:2008
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
Table E 2 – Example of calibration data at α .45
Table E 3 – Example of calibration data at α .45
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.

– 6 – 60758  IEC:2008
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.
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
– 8 – 60758  IEC:2008
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

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

– 10 – 60758  IEC:2008
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
α= log
t T
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
is the per cent transmission at a wave number of 3 410 cm , 3 500 cm , or
T
–1
3 585 cm .
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
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
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.
4.1.3 Infrared quality indications, α , α , 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:

– 12 – 60758  IEC:2008
Table 2 – Infrared quality indications for the grades
a
Maxima Pre-1987
Grades
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
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 series resonance frequency at 25 ℃. The fractional
deviation shall satisfy the following:
–6
－ fractional frequency deviation at 15 ℃: +0,5 to +1,5 × 10 ;
–6
－ fractional frequency deviation at 35 ℃: –0,5 to –1,5 × 10 .
Measurement shall be made in accordance with 4.7.3 of IEC 60122-1 .
4.1.5 Etch channel density ρ
When required, the etch channel density, ρ, per cm (measured as in 4.2.8) for each
grade, shall comply with the listings in Table 3.
Table 3 – Etch channel densities for the grades
Grade Maximum number ρ per cm
1aa 2
1a 5
1 10
2 30
3 100
4 300
60758  IEC:2008 – 13 –
4.2 Requirements and measuring methods
4.2.1 Orientation
The orientation of the seed shall be along specified directions, with a deviation of less
than 30 min from nominal.
4.2.2 Handedness
The handedness of the seed shall be specified, either right-hand or left-hand (see
Figure 2).
4.2.3 Synthetic quartz crystal dimensions
The dimension shall be measured by callipers or point callipers which enable the hollow
point of a synthetic quartz crystal to be measured (see Annex D).
4.2.3.1 Dimension along Y or Y'- axis
The dimension shall be as specified (see Figure 1d).
4.2.3.2 Dimension along Z or Z'-axis dimension shall be measured by a neck
ipers
The dimension along the Z or Z'-axis shall be specified as the maximum dimension along
the Z or Z'-axis in the greater X zone (see Figure 1c).
4.2.3.3 Dimension Z or Z'
eff etf
The Z or Z' dimension shall be specified as the minimum dimension along the Z or
eff eff
Z'-axis (see Figure 1c).
4.2.3.4 Dimension Z or Z'
mln min
The dimension shall be as specified (see Figures 1c and 1d).
4.2.3.5 Dimension along X-axis
The gross dimension along the X-axis shall be as specified (see Figure 1c).
4.2.4 Seed dimensions
4.2.4.1 Z or Z' dimension
The Z or Z'-dimension (i.e. thickness) of the Z-cut or rotated Z-cut seed shall be less
than 3 mm, unless otherwise specified.
4.2.4.2 X-dimension
The dimension X of the seed shall be as specified.
4.2.5 Imperfections
4.2.5.1 Twinning
There shall be no electrical or optical twinning in the usable region. The existence of
twinning shall be checked by visual inspection.

– 14 – 60758  IEC:2008
4.2.5.2 Cracks and fractures
There shall be no cracks or fractures in the usable region. The existence of cracks and
fractures shall be checked by visual inspection.
4.2.5.3 Inclusion density
The following two measuring methods are used and either one may be chosen.
Method 1
Inclusions within stated ranges are counted visually per cm in sample volumes within a
crystal using a stereo binocular microscope operating at 30 × to 40 × magnification
equipped for counting within either a circular or a square field and with a calibrated
reticule scale for determining particle sizes, intense side illumination (such as halogen
lamps) over a recessed black matt background, an index matching liquid (n = 1,55,
approximately) for transparency, and means of measuring the dimensions of the sample
volumes counted.
Method 2
In case it is difficult to apply method 1, crystals are compared with reference samples
appropriately representing each grade range, immersing within an index matching liquid
(n = 1,55 approximately) for transparency, or applying such liquid to the surface. The
reference samples shall be agreed upon between the supplier and the user. An example
for the reference sample selection procedure is given in Annex C.
4.2.5.3.1 Sampling
Because of the considerable costs in time, labour and money, some plan for sampling
both bars and regions within the bars is normally used by agreement between the
supplier and the buyer when quality control of either inclusion density or etch channel
density is required.
Clearly, the preferable low-cost inspection situation is the one in which the densities of
inclusions or etch channels are well below the test limits, and infrequent samples can be
justified. Since such situations are not always attainable, more rigorous inspection
strategies will sometimes be required for appropriate density control, and shall be found,
worked out, and agreed upon between the supplier and the user.
Sound statistical methods are required in order to meet appropriate agreed-upon assured
quality level tests and ensure that the crystals and the volumes counted within them are
sufficiently representative. Since sampling procedures and statistical confidence tests
are described in the literature, their principles will not be repeated here.
4.2.5.3.2 Batch sampling
In most batch sampling, a suitable sample bar or group of bars is chosen to represent
the batch population. The number of bars shall depend on the number in the batch, the
type of crystal, the intended application, the separation between the mean and the target
inclusion densities and the AQL confidence level requirement needed to provide
sufficient assurance that the batch inclusion density in each size range shall be below
their applicable grade test limits. The sample bar group shall reasonably represent the
batch with respect to inclusion densities. Deviations, if any, are allowed and shall be
towards higher, not lower, inclusion densities for safe assurance.

60758  IEC:2008 – 15 –
4.2.5.3.3 Volumes within a bar
A group of volumes within each sample bar is next chosen for inclusion counting. The
boundaries of the volumes are defined by the area of the focal field of the microscope (or
the outline of a square reticule) and either the height of the bar or the length range of the
depth adjustment of the microscope chosen for use. It is necessary to determine and
total the volumes throughout which counts are accumulated. The volumes selected for
counting should include mainly regions (usually Z-growth zones as in Figure 3) whose
material will be present and active in the finished devices and should not avoid dense
inclusion volumes within these regions. The number of volumes per bar shall be at least
six or more for reasonable statistical confidence.
The sample volume locations within a bar shall be appropriately distributed in its X-, Y-,
Z-axes to include the variations of the inclusion density with these independent variables.
Typical synthetic quartz bars (Figure 3a) are long in the Y- and small in the X- and
Z-axes dimensions. Normally, the greatest variation of inclusion density appears over a
zone's grown direction, for example the Z-dimension in the Z-zone (Figures 1a and 3).
Thus, for large Z-crystals, the sampled regions shall be located at varied Z-distances
from the seed to ensure that the bar's range of Z is well-represented by the group of
sample volumes. Similarly, any noted variations over Y or X shall be sampled, if such
variations are present.
To aid in distributing sample volumes within a typical bar, its lesser X-surface is marked
with transverse Z'-lines, perpendicular to the seed at regular 10 mm intervals over the
Y-length of the surface. Sample volumes for inclusion counting are chosen as needed
from within each rectangle formed by the marks and the crystal surfaces. To locate the
sample volumes at varied distances from the seed, in small crystals (where a Z-zone
measures less than double the field diameter of the microscope), they should be
alternated near and far from the seed. For larger crystals, the volumes should be
sequenced in Z over its range to ensure that each inclusion band is represented in the
sample volumes. Several frequently used sampling plans are illustrated in Annex A.
4.2.5.3.4 Inclusion counting
The circular or square field of view chosen for counting within its marked rectangle is
scanned vertically over its chosen X-height within the microscope's range of depth
adjustment, as follows.
If the sample is a Y-bar with a relatively small X-height, the scans will be at a series of
sites varied in Z along its length (under side illumination, with its lesser X-surface up).
Beginning in a rectangle positioned at one end of the usable zone, an inclusion count is
taken in an X-cylinder (or parallelelipiped) volume. Starting slightly below the lesser
X-surface (and not counting surface material), all visible inclusions in focus are
categorized and counted in each of the size categories required by the customer's order:
10 µm to 30 µm, 30 µm to 70 µm, 70 µm to 100 µm, and greater than 100 µm. The
microscope is then lowered and the newly focused inclusions counted and added into
their size categories. This process is continued through the chosen X-height; the
procedure is repeated at the next sample position, and so on.
The counts from the bar's sample sites in each of the four size categories are summed
by category and divided by the calculated total of the sampled volumes, to obtain an
for each category in one bar. The count averages in each
average count per cm
category from all the sample bars from a run are averaged and recorded as required to
represent the size distribution for the run. Maximum and minimum bar averages may also
be recorded, if desired or required. A numerical example is given in Annex B.
4.2.6 Evaluation of infrared quality by alpha-measurement
The infrared absorption per centimetre at one or more of 3 410, 3 500 or 3 585 wave
numbers is measured in a Y-cut slice scan as the difference between the absorption at

– 16 – 60758  IEC:2008
the chosen wave number and absorption in the background outside the band, at
–1 –1
3 800 cm or at 3 979 cm when using a single beam instrument. Since α are known
to vary directly with the total Z-growth size distribution of the crystals in one batch, a
user may designate his preference in the batch distribution for sample testing. Such
choices are often either an average Z-crystal or a maximum Z-crystal (for worst-case
maximum alpha-measurement).
The following two measuring methods are used and either one shall be chosen.
Method 1
The wave number is fixed and the positional transmission data are measured by
scanning the sample.
Method 2
The sample is fixed and the transmission data are measured at chosen wave numbers on
several points in the sample.
4.2.6.1 Preparation of the Y cut slice
The synthetic quartz crystal to be sampled is mounted on a substrate then sliced with a
quartz saw to yield at least one Y-cut slice whose thickness after lapping and polishing
will fall in the range of 5 mm to 10 mm. The 5 mm thickness is appropriate for high α
-material, to resolve its α -variations; the mid-range for medium α; and the 10 mm
thickness is appropriate for the lowest α-material to measure its small absorption.
After sawing, the slice is lapped on both major surfaces: first, with a homogenized
mixture of 25 µm abrasive; second, with a homogenized mixture of 3 µm abrasive.
Further lapping to polish is optional and is preferred for low α.
4.2.6.2 Calibration of a standard Y-cut slice in an infrared spectrophotometer
The infra-red spectrophotometer is turned on, allowed to warm and fully stabilize, then
calibrated. The normal daily calibration includes its transmission (0 % - 100 %) or
absorbance (log T =1,0 - 0) limit settings, chart speed and synchronized sample
scanning arrangement. For evaluation and normal use, a 1,5 mm width aperture is
located in the sample beam. For the lowest α-value measurements, a 5 mm width
aperture may be required. The aperture's height shall not exceed the X-dimension of the
seed or 5,0 mm. A polished Y-cut standard reference slice is placed first in the sample
holder, which is then mounted in the scanning device.
The wave number control is set at a background setting (outside, but near the OH
–1
absorption band), usually 3 800 ± 3 cm , and the sample is translated through the beam
with synchronized chart advance at the fixed wave number. Such scan
...