Overview - IEC 60444-8:2003 (Test fixture for surface mounted quartz crystal units)
IEC 60444-8:2003 specifies the test fixture and related measurement requirements for accurate determination of resonance frequency, resonance resistance and equivalent electrical circuit parameters of leadless surface-mounted quartz crystal units (SMD quartz). The standard defines how to perform measurements using the zero phase technique (as referenced in IEC 60444-4 and IEC 60444-5) and automatic network analyzer methods over the frequency ranges allowed by the fixture and optional load capacitance.
Key topics and technical requirements
- Measurement scope
- Resonance frequency, resonance resistance, parallel capacitance (C0), motional capacitance (C1) and motional inductance (L1).
- Measurement method: zero phase technique and admittance circle technique using an automatic network analyzer (per IEC 60444-5).
- Frequency ranges
- 1 MHz to 150 MHz when no external load capacitance is used.
- 1 MHz to 30 MHz when a load capacitance is applied.
- Test fixture design
- Equivalent-circuit model based on IEC 60444-1; physical size/structure adapted for leadless SMD crystals.
- Mechanical contact must reliably connect fixture terminals to the device electrodes; minimum contact pressure specified: 1.96 N (200 gf).
- Load capacitance range: ≥ 10 pF when used.
- Calibration and accuracy
- Calibration requires at least three standard impedance elements: short, open (if stray capacitance significant), and a 50 Ω standard.
- 50 Ω standard tolerance: 50 ± 5 %, phase specified in the standard.
- C-adapter board calibration uses a capacitance meter with permissible error ±0.002 pF.
- Resonance resistance accuracy given as ±2 Ω or ±10 % (as stated in the document).
- Mechanical and enclosure guidance
- No mandatory enclosure type, but IEC 61240 SMD outline recommendations are preferred.
- Overtone selection is not constrained by the fixture; measurement relies on zero phase technique.
Applications and who uses this standard
- Manufacturers of SMD quartz resonators and crystal units - for production test and design verification.
- Metrology and calibration laboratories - for traceable measurements of crystal parameters.
- Component test engineers and quality assurance teams - to specify acceptance tests in purchase contracts.
- Oscillator and frequency-control designers - to correlate measured load resonance to circuit behaviour.
- Test-fixture and ATE vendors - to design compliance fixtures and calibration procedures.
Related standards
- IEC 60444-1: Basic zero phase method and equivalent circuits
- IEC 60444-4: Load resonance measurement method
- IEC 60444-5: Automatic network analyzer methods and error correction
- IEC 60444-2: Motional capacitance phase-offset method
- IEC 61240: SMD outline drawings for frequency-control devices
This standard is essential when you need repeatable, high-accuracy measurements of leadless SMD quartz units using a dedicated test fixture and network-analyzer techniques.
Open preview (PDF)Measurement of quartz crystal unit parameters - Part 8: Test fixture for surface mounted quartz crystal units
