IEC 60444-8 pdf download – Measurement of quartz crystal unit parameters – Part 8: Test fixture for surface mounted quartz crystal units

IEC 60444-8 pdf download – Measurement of quartz crystal unit parameters – Part 8: Test fixture for surface mounted quartz crystal units
scope
This part of lEC 60444 explains the test fixture that allows the accurate measurement ofresonance frequency,resonance resistance,and equivalent electrical circuit parameters of aleadless surface mounted quartz crystal units using zero phase technique as specified in IEC60444-4 and lEC60444-5.
An equivalent circuit constant and the application frequency range obtained by using the testfixture are then shown.
ln addition, this is applied to the enclosure shown in lEC 61240 as a crystal unit without leadwires.An equivalent circuit of the test fixture and an electric values are based on lEC 60444-1and lEC 60444-4. The range of load capacitance is 10 pF or more. Calibration of themeasurement system and Cadapter board is explained hereinafter.
This document applies to the test fixture that allows the accurate measurement of resonancefrequency，resonance resistance，parallel capacitance Co,motional capacitance C, andmotional inductance Lof the crystal unit over the frequency range from 1 MHz to 150 MHzusing an automatic network analyzer, based on lEC 60444-5.
2Normative references
The following referenced documents are indispensable for the application of this document.Fordated references,only the edition cited applies. For undated references, the latest edition ofthe referenced document (including any amendments) applies.
IEC 60444-1:1986,Measurement of quartz crystal unit parameters by zero phase technique ina pi-network – Part 1: Basic method for the measurement of resonance frequency andresonance resistance of quartz crystal units by zero phase technique in a pi-network
IEC 60444-2:1980，Measurement of quartz crystal unit parameters by zero phase technique ina pi-network – Part 2: Phase offset method for measurement of motional capacitance of quartzcrystal units
IEC 60444-5:1995,Measurement of quartz crystal units parameters – Part 5: Methods for thedetermination of equivalent electrical parameters using automatic network analyzer techniquesand error correction
IEC 61240:1994，Piezoelectric devices – Preparation of outline drawings of surface-mounteddevices (SMD) for frequency control and selection – General rules
3 General issue
The test fixture and the method for measuring the resonance frequency,resonance resistance,and equivalent electrical circuit parameters must be specified in the contract between thecrystal unit supplier and the user. The crystal unit requires special consideration as it has nolead wires.
4 Leadless surface mounted quartz crystal units
4.1 Enclosure
No particular specification shall be made regarding the enclosure type. However，it isrecommended that enclosures such as those shown in iEC 61240,be used.
4.2 overtone and frequeney range
No particular specification shall be made regarding the overtone,because the measurement ismade using the zero phase technique. The frequency range is from 1 MHz to 150 MHz whenthe load capacitance is not used,and is from 1 MHz to 30 MHz when the load capacitance isused.
5 specifications of measurement method, test fixture
5.1specifications of measurement method
The measurement method is according to lEC 60444-5.The method uses the admittance circletechnique.
5.2Specifications of test fixture
An equivalent circuit of the test fixture and electric values are based on IEC 60444-1.The sizeand the structure are different in this document from those of lEC 60444-1.The size and thestructure suit leadless crystal units.
The test fixture configuration is as specified in IEC 60444-1.Figure 1 and Figure 2 show thetest fixture，but stray capacitances between measurement terminals such as C,and C2 inFigure 2 of lEC 60444-1 are not specified.Figure 3 and Figure 4 show 3-D and design of thetest fixture.
No specifications shall be made as to the structures of the test fixture to be used,except thatthey must secure the mechanical contact of the electrode performing the same function as thelead wire of an ordinary quartz crystal unit and the measurement terminals of the test fixture.
Figure 5 shows the structure of the test fixture that ensures the connection of its contact to theelectrodes of the crystal unit,thereby providing high measurement accuracy and facilitatingmeasurement.
The measurement terminal of the test fixture should form a reliable contact with the electrodeof the crystal unit in order to avoid measurement errors.
Due to this,1,96 N(200 gf) is the minimum necessary pressure of the measurement terminalof the test fixture for an electrode of the crystal unit.
NOTE lf the crystal is grounded in the application, the working frequency may depend on the orientation of thecrystal in the circuit. lt is therefore recommended to make use of the orientation mark on the crystal (for examplepad 1) when correlating the working frequency in the oscillator with the load resonance measurement according toIEC 60444-1 and IEC60444-5，