TC 49 - Piezoelectric, dielectric and electrostatic devices and associated materials for frequency control, selection and detection

IEC TS 61994-5:2023 gives the terms and definitions for sensors representing the state of the art, which are intended for manufacturing piezoelectric elements, cells, modules and the systems. This edition includes the following significant technical changes with respect to the previous edition: New terms and definitions have been added from IEC 63041-1:2021 and IEC 63041-3:2020.

IEC 62604-2:2022 applies to duplexers which can separate receiving signals from transmitting signals and are key components for two-way radio communications, and which are generally used in mobile phone systems compliant with CDMA systems such as N-CDMA in second generation mobile telecommunication systems (2G), W-CDMA / UMTS (3G) or LTE (4G). These guidelines draw attention to some fundamental questions about the theory of SAW and BAW duplexers and how to use them, which will be considered by the user before he places an order for SAW and BAW duplexers for a new application. Such a procedure will be the user’s insurance against unsatisfactory performance. Because SAW and BAW duplexers have very similar performance for the usage, it is useful and convenient for users that both duplexers are described in one standard. This edition includes the following significant technical changes with respect to the previous edition:
- the term "cross-isolation" has been added to Clause 3;
- multiplexers are described.
NOTE In this document, SAW and BAW duplexers are treated simultaneously because both duplexers are used in the same manner, especially in mobile phone systems and have the same requirements of characteristics, test method and so on.

IEC 62604-1:2022 specifies the methods of test and general requirements for SAW and BAW duplexers of assessed quality using either capability approval or qualification approval procedures. This edition includes the following significant technical changes with respect to the previous edition:
- the term "multiplexer" has been added to Clause 3.
NOTE In this document, SAW and BAW duplexers are treated simultaneously because both duplexers are used in the same manner especially in mobile phones and have the same requirements of characteristics, test method and so on.

IEC 63041-1:2021 applies to piezoelectric sensors of resonator, delay-line and non-acoustic types, which are used in physical and engineering sciences, chemistry and biochemistry, medical and environmental sciences, etc. The purpose of this document is to specify the terms and definitions for piezoelectric sensors, and to make sure from a technological perspective that users understand the state-of-art piezoelectric sensors and how to use them correctly. This edition includes the following significant technical changes with respect to the previous edition:
- the new terms "piezoelectric sensor system" and "wireless SAW sensor system" and their definitions have been added;
- new types of sensor modules and sensor system have been added;
- some symbols of sensor elements are added in Clause 4;
- a new Figure B.3 has been added in Annex B;
- Annex C has been added.

IEC 60444-6:2021 applies to the measurements of drive level dependence (DLD) of quartz crystal units. Two test methods (A and C) and one referential method (B) are described. “Method A”, based on the p-network according to IEC 60444-5, can be used in the complete frequency range covered by this part of IEC 60444. “Reference Method B”, based on the p-network or reflection method according to IEC 60444-5 or IEC 60444-8 can be used in the complete frequency range covered by this part of IEC 60444. “Method C”, an oscillator method, is suitable for measurements of fundamental mode crystal units in larger quantities with fixed conditions.
NOTE The measurement methods specified in this document are not only applicable to AT-cut, but also to other crystal cuts and vibration modes, such as doubly rotated cuts (IT,SC) and to tuning fork crystal units (by using a high impedance test fixture). This edition includes the following significant technical changes with respect to the previous edition:
- some equations have been removed and corrected;
- it has been specified in the note of the Scope that the measurement methods specified in this document are not only applicable to AT-cut but also to other crystal cuts and vibration modes.

IEC TS 61994-3:2021(E) gives the terms and definitions for piezoelectric, dielectric and electrostatic oscillators representing the state of the art, which are intended for use in the standards and documents of IEC TC 49.
The main changes with respect to the previous edition are as listed below:
- some definitions have been updated;
- the terminology given in IEC 60679-1:2017 has been taken into account;
- new terminologies are added.

IEC 61837-2:2018 deals with standard outlines and terminal lead connections as they apply to surface-mounted devices (SMD) for frequency control and selection in ceramic enclosures, and is based on IEC 61240:2016.
This edition includes the following significant technical changes with respect to the previous edition:
a. revision of the figures to match the notation of the drawings of IEC 61240:2016;
b. addition of 7 enclosures as follows: DCC-6/5032A, DCC-6/3225A, DCC-4/3215C, DCC-6/2016A, DCC-2/2012C, DCC-2/1610C, DCC-4/1210C.
As a result, this third edition contains a total of 45 enclosure types, which are listed in Table 1.

IEC 63041-3:2020 is applicable to piezoelectric physical sensors mainly used in the field of process control, wireless monitoring, dynamics, thermodynamics, vacuum engineering, and environmental sciences. This document provides users with technical guidelines as well as basic knowledge of common physical sensors.
Piezoelectric sensors covered herein are those applied to the detection and measurement of physical quantities such as force, pressure, torque, viscosity, temperature, film thickness, acceleration, vibration, and tilt angle.

IEC 63155:2020 defines the measurement method for the determination of the durability of radio frequency (RF) surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices, such as filters and duplexers, with respect to high power RF signals, which are used in telecommunications, measuring equipment, radar systems and consumer products. RF BAW devices include two types: those based on the film bulk acoustic resonator (FBAR) technology and those based on the solidly mounted resonator (SMR) technology.
This document includes basic properties of failure of RF SAW/BAW devices, and guidelines to set up the measurement system and to establish the procedure to estimate the time to failure (TF). Since TF is mainly governed by the RF power applied in the devices, discussions are focused on the power durability.
It is not the aim of this document to explain the theory, or to attempt to cover all the eventualities which can arise in practical circumstances. This document draws attention to some of the more fundamental questions which will need to be considered by the user before he/she places an order for an RF SAW/BAW device for a new application. Such a procedure will be the user's means of preventing unsatisfactory performance related to premature device failure resulting from high-power exposure of RF SAW/BAW devices.

IEC TS 61994-5:2019(E) gives the terms and definition for sensors representing the state of the art, which are intended for manufacturing piezoelectric elements, cells and the modules.

IEC 62884-4:2019 describes the methods for the measurement and evaluation of the short-term frequency stability tests of piezoelectric, dielectric and electrostatic oscillators. Its purpose is to unify the test and evaluation methods for short-term frequency stability.

IEC 60122-4:2019 is applicable to crystal units with thermistors mainly used in the field of mobile communication that requires high frequency stability such as local reference signal generator for the mobile phone base station or GPS. This document provides users with technical guidelines of crystal units with thermistors as well as basic knowledge of common crystal units with thermistors

IEC 61994-4-1:2018 gives the terms and definition for synthetic quartz crystals representing the state of the art, which are intended for manufacturing piezoelectric and optical elements. This edition includes the following significant technical changes with respect to the previous edition:
- The new terms and definitions given in IEC 60758:2016 have been taken into account;
- The general title has been changed according to the change in the title of TC 49 in 2009.

IEC 61994-4-4:2018 gives the terms and definition for single crystal wafers for surface acoustic wave (SAW) devices representing the state of the art. This edition includes the following significant technical changes with respect to the previous edition:
- the new terms and definitions given in IEC 62276:2016 have been taken into account;
- the general title has been changed according to the change in the title of TC 49 in 2009.
- the part title has been changed according to the title of IEC 62276:2016.

IEC 62884-3:2018 describes the methods for the measurement and evaluation of frequency aging tests of piezoelectric, dielectric and electrostatic oscillators, including Dielectric Resonator Oscillators (DRO) and oscillators using FBAR (hereinafter referred to as "Oscillator"). The purpose of those tests is to provide statistical data supporting aging predictions.
This document was developed from the works related to IEC 60679-1:2007 (third edition), the measurement techniques of which were restructured into different parts under a new project reference. This document describes the measurement method for frequency aging only.

IEC 63041-1:2017 applies to piezoelectric sensors of resonator, delay-line and non‑acoustic types, which are used in physical and engineering sciences, chemistry and biochemistry, medical and environmental sciences, etc. The purpose of this document is to specify the terms and definitions for the piezoelectric sensors, and to make sure from a technological perspective that users understand the state‑of-art piezoelectric sensors and how to use them correctly.

IEC 63041-2:2017 is applicable to piezoelectric chemical sensors mainly used in the field of biological, medical, gas and environmental sciences. It provides users with technical guidelines on biochemical sensors as well as basic knowledge of common chemical sensors.

Describes a high-performance backplane bus for use in microprocessor bases systems. This parallel bus supports single- and block-transfer cycles on a 32-bit non-multiplexed address and data highway. Transmission is governed by an asynchronous handshaken protocol. The bus allocation provides for multiprocessor architectures. This bus also supports inter-module interrupts for facilitating quick response to internal and external events. The mechanics of the boards and chassis are based on IEC 60297.[
]Note: -1.This bus is similar to the VME bus. 2.For the price of this publication, please consult the ISO/IEC price-code list.

IEC 62604-2:2017 concerns duplexers which can separate receiving signals from transmitting signals and are key components for two-way radio communications, and which are generally used in mobile phone systems compliant with CDMA systems such as N-CDMA in second generation mobile telecommunication systems (2G), W-CDMA / UMTS (3G) or LTE (4G).
This second edition cancels and replaces the first edition published in 2011. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
- diplexers are described;
- duplexers with a balanced RX port are considered in the measurement method subclause (7.3).
NOTE In this standard, SAW and BAW duplexers are treated simultaneously because both duplexers are used in the same manner especially in mobile phone systems and have same requirements of characteristics, test method and so on.

IEC 62884-2:2017 specifies the methods for the measurement and evaluation of the phase jitter measurement of piezoelectric, dielectric and electrostatic oscillators, including dielectric resonator oscillators (DROs) and oscillators using a thin-film bulk acoustic resonator (FBAR) (hereinafter referred to as an "Oscillator") and gives guidance for phase jitter that allows the accurate measurement of RMS jitter.
In the measurement method, phase noise measurement equipment or a phase noise measurement system is used.
NOTE Dielectric resonator oscillators (DROs) and oscillators using FBAR are under consideration.

IEC 60679-1:2017 specifies general requirements for piezoelectric, dielectric and electrostatic oscillators, including Dielectric Resonator Oscillators (DRO) and oscillators using FBAR (hereinafter referred to as "Oscillator"), of assessed quality using either capability approval or qualification approval procedures.
NOTE Dielectric Resonator Oscillators (DRO) and oscillators using FBAR are under consideration.
This edition includes the following significant technical changes with respect to the previous edition:
a) the title has been changed;
b) additional matters related to oscillator using SAW or MEMS resonator in "Terms, definitions and general information" have been included;
c) measurement methods of IEC 60679-1:2007 have been removed (they will be moved to IEC 62884 series);
d) the content of Annex A has been extended;
e) a new term and definition DIXO (Digital interfaced Crystal Oscillator) has been added;
f) a new term and definition SSXO (Spread Spectrum Crystal Oscillator) has been added;
g) Annex D has been added.

IEC 62884-1:2017 specifies the measurement techniques for piezoelectric, dielectric and electrostatic oscillators, including Dielectric Resonator Oscillators (DROs) and oscillators using FBAR (hereinafter referred to as "Oscillator")

IEC 60444-8:2016 describes test fixtures suitable for leadless surface mounted quartz crystal units in enclosures as defined in IEC 61837 (all parts). These fixtures allow the measurement of (series) resonance frequency, (series) resonance resistance, and equivalent electrical circuit parameters L1, C1 and C0 using the measurement techniques specified in IEC 60444-5 and for the determination of load resonance frequency and load resonance resistance according to IEC TR 60444-4 and IEC 60444-11.
Two test fixtures are described in this document:
1) A fixture using the p-network circuit with electrical values as described in IEC 60444-1 for measurements in transmission mode up to 500 MHz. This fixture includes optional means to add physical load capacitors for the measurement of load resonance parameters up to 30 MHz in accordance with IEC 60444-4. The range of load capacitance is 10 pF or more. Calibration of the measurement system and CL adapter board is explained hereinafter.
2) A fixture based on the reflection method, suitable for a frequency range up to 1 200 MHz. No provisions for adding a physical load capacitance are anticipated. Load resonance parameters can be measured by using the method of IEC 60444-11.
This edition includes the following significant technical changes with respect to the previous edition:
a) modification of Clause 1;
b) modification of 5.2;
c) modification of 5.3;
d) modification of 5.4;
e) 6.3 Calibration of the reflection measurement system.

IEC 62276:2016 applies to the manufacture of synthetic quartz, lithium niobate (LN), lithium tantalate (LT), lithium tetraborate (LBO), and lanthanum gallium silicate (LGS) single crystal wafers intended for use as substrates in the manufacture of surface acoustic wave (SAW) filters and resonators. This edition includes the following significant technical changes with respect to the previous edition:
- Corrections of Euler angle indications in Table 1 and axis directions in Figure 3.
- Definition of "twin" is not explained clearly enough in 3.3.3. Therefore it is revised by a more detailed definition.
- Etch channels maximum number at quartz wafer of seed which do not pass through from surface to back surface are classified for three grades in 4.2.13 a). Users use seed portions of quartz wafers for devices. They request quartz wafers with less etch channels in seeds to reduce defects of devices. The classification of etch channels in seed may prompt a rise in quartz wafer quality.

IEC 61240:2016 sets out general rules for drawing all dimensional and geometrical characteristics of a surface-mounted piezoelectric device package (referred to in this document as SMD) in order to ensure mechanical inter-changeability of all outline drawings of the SMDs for frequency control and selection. This edition includes the following significant technical changes with respect to the previous edition:
- outline drawings have been changed from three views (top, front and bottom) to that based on ISO layout in the third-angle projection, in which the view from the right has been added to the top, front and bottom views;
- reference line and geometrical dimensions of the package for enclosures have been changed for practical use;
- information on miniaturized leadless ceramic enclosures of piezoelectric devices (SMD) for frequency control and selection has been included in an annex.

IEC 60758:2016 applies to synthetic quartz single crystals intended for manufacturing piezoelectric elements for frequency control, selection and optical applications. This edition includes the following significant technical changes with respect to the previous edition:
- order rearrangement and review of terms and definitions;
- abolition as a standard of the infrared absorbance coefficient α3410;
- addition of the value measurement explanation by FT-IR equipment in annex;
- addition of the synthetic quartz crystal standards for optical applications.

IEC 62575-1:2015 specifies the methods of test and general requirements for RF BAW filters of assessed quality using either capability approval or qualification approval procedures. Conventional crystal filters standardized in the IEC 60368 series are not covered by this standard.

IEC 60862-1:2015 specifies the methods of test and general requirements for SAW filters of assessed quality using either capability approval or qualification approval procedures. This edition includes the following significant technical changes with respect to the previous edition:
- the terms and definitions from IEC 60862-2:2002 are included;
- the measurement method for the balanced type filter is described;
- the electrostatic discharge (ESD) sensitivity test procedure is considered.

IEC 62604-1:2015 specifies the methods of test and general requirements for SAW and BAW duplexers of assessed quality using either capability approval or qualification approval procedures.

IEC 61338-1-5:2015 describes a measurement method for resistance and effective conductivity at the interface between conductor layer and dielectric substrate, which are called interface resistance and interface conductivity. This first edition cancels and replaces IEC PAS 61338-1-5 published in 2010. This edition includes the following significant technical changes with respect to the previous edition:
a) description of technical content related to patents (Japanese patent numbers JP3634966, JP3735501) in the Introduction;
b) changes to normative references;
c)addition to bibliography.

IEC 61837-3:2015 deals with standard outlines and terminal lead connections as they apply to SMDs for frequency control and selection in metal enclosures and is based on IEC 61240 which standardized layout rules of outline drawings of the surface-mounted devices. This edition includes the following significant technical changes with respect to the previous edition:
- The outline drawing is defined as one set of drawings consisting of four views, which are the view from above, the front view, the view from the right, and the view from below; the view from the right was drawn optionally in the previous edition.
- The height of package (G1) is eliminated, instead total height is expressed by the symbol letter G or with a subscript number.
- The dimensions of terminal lead spacing are shown by the centre position of the terminal leads and its basic value e is 2.54 x n mm (n is an integer) and 1,27 x n mm for package dimensions smaller than 6 mm (See IEC 61240:2012, 5.5). If the terminal lead spacing is not a multiple of the basic value, a subscript number such as e1, e2 is attached, e.g. e1, e2, etc. If there are plural spacing values, the subscript number is followed by a hyphen and numbers such as e1-1, e1-2 , etc.
- In terminal land areas, the lengths of each terminal pad are now expressed with maximum values for consumer's convenience. They were expressed as minimum values in the previous edition of IEC 61837-3.
- If there are plural identical enclosures with different height, each enclosure was expressed by a dash (/) and a two-digit number after the basic type name. The identity references are given in the table of the sheet.
- The configurations of the enclosures were revised as shown in Table 1.
This publication is to be read in conjunction with IEC 61240:2012.

IEC 61837-4:2015 specifies the outline drawings and terminal lead connections for surface piezoelectric devices with hybrid enclosure outlines and is based on IEC 61240:2012 which standardized layout rules of outline drawings of surface-mounted device. This edition includes the following significant technical changes with respect to the previous edition:
- Outline drawing is defined as one set of drawings consisting of four views, which are the view from above, the front view, the view from the right, and the view from below, instead of one set consisting of three views as provided in the previous edition.
- The configurations of the enclosures were revised as shown in Table 1.
This publication is to be read in conjunction with IEC 61240:2012.

IEC 61837-2:2011 deals with standard outlines and terminal lead connections as they apply to surface-mounted devices (SMD) for frequency control and selection in ceramic enclosures, and is based on IEC 61240. In this edition, types of enclosures are renamed to express their features in their names for better understanding. The relative comparison of new types with old ones is listed in Table 1. New names of enclosures express configuration type, terminal lead numbers, sizes and arrangement of terminal pads. The details of definition are shown in Clause 3: Configuration of enclosures, and Clause 4: Designation of types. Enclosures in this new edition are based on IEC 61240. In this standard, 27 enclosures are added to the first edition of IEC 61837-2.
This publication is to be read in conjunction with IEC 61240:1994.

IEC 62761:2014-02(en-fr) gives the measurement method for nonlinear signals generated in the radio frequency (RF) surface acoustic wave (SAW) and bulk acoustic wave (BAW) devices such as filters and duplexers, which are used in telecommunications, measuring equipment, radar systems and consumer products. It includes basic properties of non-linearity, and guidelines to setup the measurement system and to establish the measurement procedure of nonlinear signals generated in SAW/BAW devices.

IEC 60444-6:2013 applies to the measurements of drive level dependence (DLD) of quartz crystal units. Two test methods and one referential method are described. This edition includes the following significant technical changes with respect to the previous edition:
a) DLD measurement with oscillation circuit had the traditional method to detect the DLD abnormal modes at present time. Therefore, this method made the transition to the Annex B.
b) High reliability crystal unit is needed to use for various applications at the present day, in order to upgrade the inspection capabilities for DLD abnormal modes, the multi-level reference measurement method was introduced into this specification.

IEC 60679-3:2012 specifies the outline dimensions and lead connections for quartz crystal controlled oscillators with lead enclosures. This edition includes the following significant technical changes with respect to the previous edition:
- CO 01, CO 07, CO 10, CO 17 and CO 18 were deleted;
- The current pin layout of CO 06 was deleted. And new pin layout of CO 06 was added as CO 40;
- New layout of CO 15 was added as CO 41;
- Two new enclosures, CO 42 and CO 43 were added. Therefore revised edition includes 15 types of enclosures as in Table 1 of Clause 5.

IEC 62276:2012 applies to the manufacture of synthetic quartz, lithium niobate (LN), lithium tantalate (LT), lithium tetraborate (LBO), and lanthanum gallium silicate (LGS) single crystal wafers intended for use as substrates in the manufacture of surface acoustic wave (SAW) filters and resonators. This edition includes the following significant technical changes with respect to the previous edition:
- terms and definitions are rearranged in accordance with the alphabetical order;
- "reduced LN" is appended to terms and definitions;
- "reduced LT" is appended to terms and definitions;
- reduction process is appended to terms and definitions.

IEC 62575-2:2012 gives practical guidance on the use of RF BAW filters which are used in telecommunications, measuring equipment, radar systems and consumer products. General information, standard values and test conditions will be provided in a future IEC standard. This part of IEC 62575 includes various kinds of filter configurations, of which the operating frequency range is from approximately 500 MHz to 10 GHz and the relative bandwidth is about 1 % to 5 % of the centre frequency.

IEC 61240:2012 sets out general rules for drawing all dimensional and geometrical characteristics of a surface-mounted piezoelectric device package (referred to in this standard as SMD) in order to ensure mechanical inter-changeability of all outline drawings of the SMDs for frequency control and selection. This edition includes the following significant technical changes with respect to the previous edition:
- outline drawings have been changed from three views (top, front and bottom) to that based on ISO layout in the third-angle projection, in which the view from the right has been added to the top, front and bottom views;
- reference line and geometrical dimensions of the package for enclosures have been changed for practical use;
- information on miniaturized leadless ceramic enclosures of piezoelectric devices (SMD) for frequency control and selection has been included in an annex.

IEC 60862-2:2012 gives practical guidance on the use of SAW filters which are used in telecommunications, measuring equipment, radar systems and consumer products. IEC 60862-1 should be referred to for general information, standard values and test conditions. This part of IEC 60862 includes various kinds of filter configuration, of which the operating frequency range is from approximately 10 MHz to 3 GHz and the relative bandwidth is about 0,02 % to 50 % of the centre frequency. It is not the aim of this standard to explain theory, nor to attempt to cover all the eventualities which may arise in practical circumstances. This standard draws attention to some of the more fundamental questions, which should be considered by the user before he places an order for a SAW filter for a new application. Such a procedure will be the user's insurance against unsatisfactory performance. This edition includes the following significant technical changes with respect to the previous edition:
- Clause 3 "Terms and definitions" has been deleted to be included in the next edition of IEC 60862-1;
- the tapered IDT filter and the RSPUDT filter have been added to the clause of SAW transversal filters. Also DART, DWSF and EWC have been added as variations of SPUDT;
- the balanced connection has been added to the subclause of coupled resonator filters;
- recent substrate materials have been described;
- a subclause about packaging of SAW filters has been added.

IEC 61837-1:2012 deals with standard outlines and terminal lead connections as they apply to SMDs for frequency control and selection in plastic moulded enclosures and is based on IEC 61240.
This publication is to be read in conjunction with IEC 61240:1994.

IEC 62604-2:2011 concerns the duplexers, which can separate receiving signal from transmitting signal and are key components for two-way radio communications. They are generally used in mobile phones using CDMA systems such as N-CDMA, W-CDMA / Universal Mobile Telecommunication System (UMTS). So far, dielectric duplexers have been mainly used. However, recently SAW duplexers, which are utilized surface acoustic wave (SAW), are becoming popular and replacing the dielectric duplexers year by year in recent mobile phones, because of their advantage of small size, light weight and good electrical performances. In addition to SAW duplexers, BAW duplexers, which are utilized bulk acoustic wave (BAW), are also becoming in the spotlight and popular because of their higher Q property and better performances especially in PCS band. It is neither the aim of these guidelines to explain theory, nor to attempt to cover all the eventualities which may arise in practical circumstances. These guidelines draw attention to some of the more fundamental questions, which should be considered by the user before he places an order for SAW and BAW duplexers for a new application. Such a procedure will be the user's insurance against unsatisfactory performance. Because SAW and BAW duplexers have very similar performance for the usage, it is useful and convenient for users that both duplexers are described in one standard.

IEC/TS 61994-3:2011(E) specifies the terms and definitions for piezoelectric dielectric oscillators representing the state-of-the-art, which are intended for use in the standards and documents of IEC TC 49.

IEC/TS 61994-2:2011 is a technical specification that gives the terms and definitions for piezoelectric and dielectric filters representing the present state of the art, which are intended for use in the standards and documents of IEC technical committee 49. The main changes with respect to the previous edition are listed below:
- definitions updated,
- terminology given in orderly sequence,
- new terminologies are added,
- drawings inserted for easier understanding.

IEC/TS 61994-4-2:2011 specifies the terms and definitions for piezoelectric ceramics representing the present state-of-the-art, which are intended for use in the standards and documents of IEC technical committee 49. The main changes with respect to the previous edition are:
- definitions updated;
- terminology given in orderly sequence;
- drawing inserted for easier understanding the vibration modes.

IEC 60368-3:2010 specifies the outline drawing for piezoelectric filters with lead enclosures. This edition includes the following significant technical changes with respect to the previous edition:
a) four enclosure types (CF05, CF06, CF07 and CF09) have been deleted from previous edition, IEC 60368-3 Ed. 3.0;
b) now standardized enclosures are totally 16 types. These are listed in Table.1.

IEC 60122-3:2010 specifies the outline drawing for quartz crystal units with lead enclosures. The main changes with respect to the previous edition are as follows: 12 of the 48 enclosure types contained in the previous edition have been deleted.

IEC 60444-11:2010 defines the standard method of measuring load resonance frequency fL at the nominal value of CL, and the determination of the effective load capacitance CLeff at the nominal frequency for crystals with the figure of merit M > 4.