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Keysight Technologies
Materials Measurement:
PCB Materials
Application Brief
02 | Keysight | Materials Measurement: Dielectric Materials - Application Brief
Overview Solution
The dielectric properties measurement such as relative permit- The resonant cavity method provides high accuracy in the mea-
tivity (dielectric constant: Dk) and dielectric loss tangent (dis- surement at speciic resonant frequency points. You can measure
sipation factor: Df) is essential for the development and quality Dk and Df at multiple frequency points with high-order resonant
assurance of PCB materials. Traditionally, the dielectric properties frequencies or using plural resonant cavities. For example, the
of PCB materials for commercial use have been tested at rela- method with Split Post Dielectric Resonators (SPDR) is one of the
tively low frequencies such as 1 MHz and 1 GHz. The required easiest and highest accuracy methods for measuring complex
measurement frequencies are being increased in line with the permittivity and loss tangent of low loss and thin sheet materi-
trend to higher data transfer speeds for mobile handsets, PCs and als 1. It can provide a convenient, accurate, and nondestructive
tablet devices. For example, PCB materials for wireless communi- measurement of a substrate and printed circuit board. The SPDR
cation devices are tested at frequency points between 1 GHz and ixtures can be purchased in single frequencies from 1 to 22 GHz
10 GHz frequency range. from QWED or through Keysight Special Handling Engineering.
Keysight offers a complete solution that includes the 85071E Op-
tion 300 software and an Keysight vector network analyzer 1,2
E5063A network analyzer with 85071E Option 300 software
Dielectric Resonator
Sample
Dielectric Resonator
Figure 2. Structure of Split Post Dielectric Resonator (SPDR)
SPDR ixture
Figure 1. Typical system coniguration with SPDR
Figure 3. Measurement result with SPDR fixture at 9 GHz
Problem
PCB materials require low dielectric loss tangent to keep low If you need to measure dielectric properties with very wide fre-
transmission loss of digital signals. So, measurement systems are quency ranges for preliminary investigation, the transmission line
required to measure dielectric properties accurately against low method can be used 2. A trade off of the transmission line method
loss materials (Df is around 10 -3). Because the values of dielec- is that the measurement accuracy is reduced for very low loss
tric properties are frequency dependent in general, users need materials 7. One recommendation would be the combination of the
to measure dielectric properties at several frequency points to resonant cavity method and the transmission line method. You
evaluate the quality of the PCB material. can get broad frequency range results with the transmission line
method irst, then use a resonant cavity to acquire more precise
results for frequency points of interest.
03 | Keysight | Materials Measurement: Dielectric Materials - Application Brief
Conclusion References
The resonant cavity method is gaining in popularity as a response 1. Split Post Dielectric Resonators for Dielectric Measurements
to the growing measurement needs at higher frequencies for of Substrates, Application note, Literature number
PCB materials measurements. The transmission line method can 5989-5384EN
complement the resonant cavity method with its availability for
a wide frequency range measurement. For more information, ap- 2. Basics of Measuring the Dielectric Properties of Materials,
plications notes and white papers are available under references. Application note, Literature number 5989-2589EN
The following table shows the typical frequency ranges depend- 3. J. Krupka, R. G. Geyer, J. Baker-Jarvis and J. Ceremuga,
ing on measurement methods. "Measurements of the Complex Permittivity of Microwave
Circuit Board Substrates Using Split Dielectric Resonator and
Resonant Cavity Techniques," pp. 21-24, DMMA'96
Methods Typical frequency range Conference, Bath, U.K. 23-26 Sept. 1996
Parallel plate8 Up to 1 GHz
4. J. Krupka, A. P. Gregory, O. C. Rochard, R. N. Clarke, B.
Transmission line 100 MHz to 110 GHz
Riddle and J. Baker-Jarvis, "Uncertainty of Complex
Resonant cavity 1 GHz to 40 GHz
Permittivity Measurements by Split-Post Dielectric
Resonator Technique", Journal of the European Ceramic
Society, vol.21, pp.2673-2676, 2001
5. J. Coonrod and A. F. Horn III, "Understanding Dielectric
Constant for Microwave PCB Materials," High Frequency
Electronics, July 2011
6. K. Fukunaga and S. Kurahashi, "Dielectric Properties of
Printed Circuit Board Insulations at Microwaves and
Millimetre Waves," ICEAA 2007
7. J. Sheen, "Comparisons of Microwave Dielectric Property
Measurements by Transmission/Relection Techniques and
Resonance Techniques," Meas. Sci. Technol., vol. 20,
no. 4, 2009
8. Solutions for Measuring Permittivity and Permeability with
LCR Meters and Impedance Analyzers, Application note,
Literature number 5980-2862EN
Web Resources
Visit our websites for additional product information.
Materials Test Equipment:
www.keysight.com/find/materials
Network Analyzers:
www.keysight.com/find/na
Impedance Analyzers and LCR Meters:
www.keysight.com/find/impedance
04 | Keysight | Materials Measurement: Dielectric Materials - Application Brief
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services, please contact your local Keysight
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