Overview
IEC 61189-2-721:2015 is an international standard published by the International Electrotechnical Commission (IEC) that specifies test methods for determining key electrical properties of copper clad laminates (CCLs) used in interconnection structures. The standard focuses on measuring the relative permittivity (dielectric constant) and loss tangent (dissipation factor) of these materials at microwave frequencies ranging from 1.1 GHz to 20 GHz. The measurement technique employs a split post dielectric resonator (SPDR), an advanced test fixture that ensures highly accurate characterization of dielectric materials critical for high-frequency electronic applications.
This standard is integral for manufacturers, designers, and quality control specialists working with copper clad laminates and dielectric base materials in printed circuit boards (PCBs) and other electronic interconnection assemblies. Accurate electrical property data at microwave frequencies is essential for optimizing signal integrity, minimizing electromagnetic losses, and ensuring device reliability.
Key Topics
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Test Specimens and Preparation
Guidance is provided on specimen size, preparation, thickness measurement, and marking to ensure consistency and repeatability in testing results.
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Test Equipment Requirements
The standard outlines use of equipment including vector network analyzers (VNAs), SPDR test fixtures, micrometers, circulating ovens, and temperature-controlled test chambers for precise measurement conditions.
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Measurement Procedures
Detailed steps cover:
- Preconditioning of specimens
- Room temperature testing
- Variable temperature testing
- Calibration and connection of test fixtures to VNAs
- Resonance frequency and quality factor (Q-factor) determination with and without specimens
- Calculation methods for extracting relative permittivity and loss tangent from measurements
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Temperature Influence
Procedures to assess dielectric properties at different temperatures allow for evaluation of material behavior under operational environmental variations.
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Accuracy and Reporting
Recommendations for maintaining equipment, ensuring measurement accuracy, and reporting results comprehensively for industry use.
Applications
IEC 61189-2-721:2015 is essential in industries where microwave frequency performance of PCBs and interconnection structures impacts the overall product effectiveness. Typical applications include:
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High-Frequency PCB Manufacturing
Ensuring copper clad laminates meet dielectric specifications critical for RF and microwave circuits.
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Telecommunications Equipment
Evaluation of materials used in antenna feeds, waveguides, and microwave modules.
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Aerospace and Defense Electronics
Testing materials destined for radar, satellite communication systems, and high-reliability electronics requiring stringent dielectric performance.
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Automotive Radar and Sensor Systems
Characterization of laminates used in advanced driver-assistance and autonomous vehicle technology.
Utilizing the SPDR measurement technique facilitates the selection and qualification of substrate materials that optimize signal transmission, minimize losses, and enhance device longevity.
Related Standards
Professionals working with IEC 61189-2-721:2015 should consider other related standards to complement this test method:
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IEC 61189 series – Comprehensive test methods for electrical materials and printed boards, covering a wide range of electrical and mechanical properties.
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IPC-4101 – Specification for base materials used in rigid and multi-layer PCBs, addressing materials’ electrical and mechanical performance.
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ISO/IEC 17025 – General requirements for the competence of testing and calibration laboratories, ensuring quality in material testing.
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IEEE standards on dielectric measurements – Relevant for advanced testing and characterization of dielectric materials at high frequencies.
By adhering to IEC 61189-2-721:2015 and related international guidelines, manufacturers and researchers can accurately measure and optimize copper clad laminates for critical microwave frequency applications, ensuring performance and reliability in advanced electronic assemblies.
Keywords: IEC 61189-2-721, relative permittivity, loss tangent, dielectric constant, dissipation factor, copper clad laminate, split post dielectric resonator, microwave frequency testing, PCB materials testing, interconnection structures, vector network analyzer, microwave dielectric measurement, high-frequency laminates.
Open preview (PDF)Test methods for electrical materials, printed boards and other interconnection structures and assemblies - Part 2-721: Test methods for materials for interconnection structures - Measurement of relative permittivity and loss tangent for copper clad laminate at microwave frequency using a split post dielectric resonator
