Understanding Dielectric Constant and Dissipation Factor in Material Testing
Dielectric constant (permittivity) and dissipation factor (loss tangent) are fundamental electrical properties that characterise how materials store and dissipate electrical energy in alternating electric fields. These properties are critical for selecting insulating materials for electrical and electronic applications—from PCB substrates and cable insulation to capacitor dielectrics and semiconductor packaging. For companies seeking dielectric testing at a US-based ASTM testing lab, Infinita Lab provides comprehensive electrical property characterisation through its accredited laboratory network.
What These Properties Measure
Dielectric Constant (Dk or εr)
The dielectric constant measures a material’s ability to store electrical energy relative to a vacuum. Higher Dk values indicate greater charge storage capacity (desirable for capacitors), while lower Dk values reduce signal propagation delay and crosstalk (desirable for high-frequency PCB substrates and semiconductor packaging). Values range from approximately 2.1 for PTFE to over 1,000 for certain ceramics.
Dissipation Factor (Df or tan δ)
The dissipation factor measures the fraction of the stored electrical energy lost as heat during each AC cycle. Lower Df indicates more efficient energy storage with less heating—critical for high-frequency applications where dielectric heating can degrade performance and reliability. Low-loss materials like PTFE (Df ~0.0002) are essential for RF and microwave applications.
Testing Methods and Standards
ASTM D150 is the primary standard for measuring Dk and Df of solid electrical insulating materials at frequencies from 1 Hz to several GHz. Test specimens are placed between parallel plate electrodes in a capacitance bridge or impedance analyser. IEC 60250 is the international equivalent. ASTM D2520 covers measurements in microwave frequency ranges using cavity perturbation methods.
Industry Applications
Dielectric property testing serves PCB substrate selection for the electronics and semiconductor industries (low Dk/Df for 5G and high-speed digital), capacitor material development and quality control, cable and wire insulation specification, transformer and motor insulation evaluation, random and antenna material selection for the aerospace sector, and IC packaging material characterisation.
Partnering with Infinita Lab for Optimal Results
Infinita Lab addresses the most frustrating pain points in the Dielectric Testing process: complexity, coordination, and confidentiality. Our platform is built for secure, simplified support, allowing engineering and R&D teams to focus on what matters most: innovation. From kickoff to final report, we orchestrate every detail—fast, seamlessly, and behind the scenes.
Looking for a trusted partner to achieve your research goals? Schedule a meeting with us, send us a request, or call us at (888) 878-3090 to learn more about our services and how we can support you. Request a Quote
Frequently Asked Questions (FAQs)
What is the dielectric constant? Dielectric constant (Dk or relative permittivity) measures how much electrical energy a material stores compared to a vacuum. It determines capacitance, signal speed, and impedance in electrical and electronic applications.
What is the dissipation factor? Dissipation factor (Df or tan δ) measures the ratio of energy lost as heat to energy stored per AC cycle in a dielectric material. Lower values indicate less signal loss and less dielectric heating.
What ASTM standard covers dielectric testing? ASTM D150 is the primary standard for measuring dielectric constant and dissipation factor of solid insulating materials. ASTM D2520 covers microwave frequency measurements. IEC 60250 is the international equivalent.
Why do 5G applications need low-Dk materials? 5G operates at higher frequencies, where signal loss increases with Dk and Df values. Low-Dk substrates minimize signal propagation delay and impedance mismatches, while low Df reduces signal attenuation at millimetre-wave frequencies.
How do temperature and frequency affect dielectric properties? Both Dk and Df typically change with temperature and frequency. Many polymers show increasing Df at higher frequencies due to molecular relaxation losses. Temperature increases generally reduce Dk in ceramics but may increase Df in polymers.
