Broadband Dielectric Characterization of Polymers and Ceramics in the 5G

Frequency RangeMike Lanagan

Professor of Engineering Science and MechanicsPenn State University

Presented at the iNEMI WebinarApril 8, 2021

Acknowledgements: Steve Perini for the high frequency dielectric measurements, Financial support from

The Center for Dielectrics and Piezoelectrics

Listen to webinar recording: https://youtu.be/TtdDEe3PfTsIf you have trouble accessing the recording, contact Cynthia Williams (cwilliams@inemi.org)

Penn State UniversityOver 10,000 engineering students

Over 100,000 students across the Commonwealth

Copyright © IDTechEx. | www.IDTechEx.com Dr. Luyun Jiang 5G: An Overview

Evolution of the cellular base station: overviewChanges 1: active antennas unit (AAU)

Changes 2: fixed wireless

Changes 3: architecture

Source: NXP

Dielectric Materials for 5G ApplicationsMaterial Permittivity Loss Frequency

[GHz] Ref

PTFE-Glass 2.5 .001 6 CoonrodLCP 3.2 0.004 60 Thompson

Glass 4.2 0.005 10 LanaganLTCC 7.5 0.002 40 Amey

Alumina 9.8 0.0002 60 MarcoZTS 38 .00006 2 Moulson

BNTO 77 .003 2 Moulson

Amey, et al. (1999). Characterization of low loss LTCC materials at 40 GHz. In SPIE proceedings series, 89-93. LTCC is Low Temperature Co-fired Ceramics.Coonrod, J. (2018). ‘Selecting circuit material for the different spectra of 5G power amplifiers. Microw. J. E-Book, 18-21. PTFE is Polytetrafluorethylene.Lanagan, et al.. (2020). Dielectric polarizability of alkali and alkaline-earth modified silicate glasses at microwave frequency. Applied Physics Letters, 116(22), 222902.Marco, et al, T. (2016). Dielectric properties of pure alumina from 8 GHz to 73 GHz. Journal of the European Ceramic Society, 36(14), 3355-3361.Moulson, A. J., & Herbert, J. M. (2003). Electroceramics: materials, properties, applications. John Wiley & Sons.Thompson, et al., J. (2004). Characterization of liquid crystal polymer (LCP) material and transmission lines on LCP substrates from 30 to 110 GHz. IEEE Transactions on Microwave Theory and Techniques, 52(4), 1343-1352.

https://www.microwavejournal.com/articles/30170-transmission-lines?page=5

Fiedziuszko, S. J., & Holmes, S. (2001). Dielectric resonators raise your high-Q. IEEE Microwave magazine, 2(3), 50-60.

https://images.app.goo.gl/SRHGV7BsJdWevmLTA

material properties for

5G

• Relative permittivity εr or dielectric constant Dk• Miniaturization for higher εr values• Trending toward lower Dk as frequency increases• Permittivity range of interest 1< ε r <100

• Dielectric loss (tanδ or 1/Q)• Related to overall device loss and quality factor Q• Low loss is important for filters and transmission lines• Loss range 10-5 < tanδ < 10-2 or 105 > Q > 102

• Temperature dependence• Permittivity and loss change with temperature• Affects the temperature dependence of frequency for filters• Coefficient of temperature │ τT │< 100 ppm

* Source: Takano Katsuyoshi et al., Electronic Ceramics (in Jpn), Sept. 1991

> +100ppm/°C

+50 ~ +100ppm/°C

0 ~ +50ppm/°C

0 ~ -50ppm/°C

-50 ~ -100ppm/°CTiO2

ST

CT

BPNT

BZT

BNT

B2T9

MT

MCT

BZN

BT4

SZ

CZ

BZ

L2T2

Al2O3

ANT

τf -legend

Resonator

Block filter

DecouplingBi-pyrochlore

ZTT

LTCCZNBV

Thin films

ZST

PCLMN

MT: MgTiO3, BZT: Ba(Zn1/3Ta2/3)O3, BZN: Ba(Zn1/3Nb2/3)O3, MT: MgTiO3, ZTT: ZnTiO3+TiO2, ZST: Zr(Sn,Ti)O4, B2T9: Ba2Ti9O20, MCT: (Mg,Ca)TiO3, PCLMN: (Pb,Ca,La)(Mg,Nb)O3, L2T2: Ln2Ti2O7 ,BT4: BaTi4O9, BNT: BaO-Nd2O3-TiO2, BPNT: BaO-PbO-Nd2O3-TiO2, SZ: SrZrO3, BZ: BaZrO3, CZ: CaZrO3ZNBV: ZnNb2O6-BiVO4, Bi-pyrochlore: Bi-Zn-Nb-O, CT: CaTiO3, ST: SrTiO3, ANT: Ag(Nb,Ta)O3

Dielectric Property Ranges for 5G Devices

0 50 100 150 200 250 300 350 400

100

1000

10000

100000

1000000

Q

(@

1 G

Hz)

Relative Permittivity

Loss or tan δ

10-2

10-3

10-4

10-5

10-6

0.5 1.0 1.5 2.0 2.5-1000

-800

-600

-400

-200

0

200

400

BiScO3-Ba(MgNb)O3-syst.

Paraelectrics

Ferroelectrics

Target for LTCC dielectricmaterials development

Ba(ZnTa)O3-syst.

Zr(TiSn)O4-syst. BaO-PbO-Nd2O3-TiO2 syst.

Bi-Pyrochlores

SrZrO3

Nd2Ti2O7 Ag(Nb,Ta)O3

CaZrO3

LaAlO3

TiO2

BaTi0.1Zr0.9O3

BaZrO3

BaSnO3

Al2O3

Polymers

CovalentInorganics

SiO2

SiC

MgOAlkali HalidesLiFKCl

Tenp

erat

ure

Depe

nden

ce

of D

iele

ctric

Con

stan

t (pp

m/K

)

Log10 Dielectric Constant (Log k)3 5 10 15 20 30 50 100 200 300 400k

Harrop, P.J., 1969. Temperature coefficients of capacitance of solids. Journal of Materials Science, 4(4), pp.370-374.

Temperature Dependent dielectric properties

Ag(NbTa)O3εr =430 Ba6-xNd8+2/3xTi18O54

εr=90

Block Miniaturization Using High Permittivity Dielectric Materials*

1.8 GHz block filters

*Valent et al., J. European Ceram. Soc., vol. 21 (2001) 2647-2651

5 mm

High Permittivity Bi-Zn-(Nb,Ta)-O System

Bi2O3 Ta2O5

Bi2(Zn1/3Ta2/3)2O7Monoclinic C2/c (β)Dielectric Constant = 61.4Tan δ < 0.001 at 1 MHzTCC = 60 ppm/ °C

(Bi3/2Zn1/2)(Zn1/2Ta3/2)O7Cubic Fd3m (α)Dielectric Constant = 71.4Tan δ < 0.005 at 1 MHzTCC = -172 ppm/ °C

ZnTa2O6

ZnO

BiTaO4

High permittivity insert for decreasing antenna size

Low permittivity window frame for high radiation efficiency

3.6 cm

Using high Dk insert to reduce 900 MHz Patch Antenna Size

Important material

properties for 5G

transmission lines

• Dielectric loss (tanδ)• Related to polarization losses in material• Loss range 10-5< tanδ <10-2

• Conductor resistivity (ρ)• Related to resistive losses in material• Resistivity range 1.6 x10-8 < ρ < 7.0 x 10-8 Ω-m

• Attenuation (α)• Related to conductor and dielectric losses

Transmission Line Configurations

Microstrip Coplanar Waveguide Waveguide

Dielectric Conductor

• Electromagnetic (EM) transmission is controlled by architecture and materials

Signal Propagation Direction

Microstrip Attenuation Increases with Frequency

Loss increases in proportion to frequency(dB is a log scale)

• Microstrip loss will become to high above 20 GHz• New Materials and New Structures will be required

at mm-wave frequency (30 to 300 GHz)

*D. Amey and S. Horowitz, 1997 IEMT/IMC proceedings

…….….

Signal Attenuation

Dielectric and Conductor Contributions to Signal Attenuation

LTCC Dielectric loss αd = 2.41 dB/m

Conductor loss αc

Metal loss αm = 2.75 dB/m Surface roughness αs = 0.5 dB/m

Radiative loss αr = 0.23

Total microstrip loss αt = 5.83 dB/m

αt= αd + αc + αr

αc= αm + αs

*L. Chai and R. Geyer and, Ferro and NIST presentation at IMAPS Advanced Technology Workshop On Ceramic Applications for Microwave Devices March 26-27, 2001Coonrod, John. "Insertion loss comparisons of common high frequency PCB constructions." IPC APEX EXPO (2013).

Power in

Power out

Signal Attenuation

𝛼𝛼 ≡𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 𝑖𝑖𝑖𝑖 − 𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 𝑃𝑃𝑜𝑜𝑜𝑜

𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃 𝑖𝑖𝑖𝑖

…….….

Dielectric Conductor Radiative

Relationship between Attenuation and Q-factor

Microstrip Resonator:

• Loss quantified by QT• Discreet frequency• No calibration required

Microstrip Transmission Line:

• Loss quantified by αT

• Swept frequency• Calibration required

To

effRn

Qcf επ

α =T

Measured Loss for Ring Resonator

αtm = 5.90 dB/m*L. Chai and R. Geyer and, Ferro and NIST presentation at IMAPS Advanced Technology Workshop On Ceramic Applications for Microwave Devices March 26-27, 2001

1QT

=1

Qd

+1

Qc

+1

Qr

Q-factor in Ring Resonators• Q is inversely proportional to energy loss• Several contributions to energy loss

– Dielectric– Conductor– Radiation (minimal)– Coupling Structure (loaded vs. unloaded Q)

Assume to beNegligibleDetermined from ring

Measurement

Determined from dielectricMeasurement

Function of metal resistivityand permeability

Dielectric Loss (tan δ or Qd ) Measurement of Alumina Substrate

• Large measurement range– 1<Dk<500– 0.0005 < tanδ < 0.02

• Substrate form factor– No metallization– No specific in-plane or

thickness dimension

Split Cavity Resonator

Microwave Input Microwave Output

Sample Input

Janezic, Michael D., and James Baker-Jarvis IEEE Transactions on microwave theory and techniques 47, no. 10 (1999): 2014-2020 Kent, G. (1988). Kent, G. (1988). IEEE transactions on microwave theory and techniques, 36(10), 1451-1454.

• For Alumina Substrate– Dk = 9.001 – tan δ = 0.0007– Qd ≡ 1/ tan δ = 1,400

Ring Resonator Fabrication with Different Electrodes

• Screen printed electrodes on alumina substrate• Ring on top and ground plane on bottom of substrate• Ag paste fired at 850 C for 15 minutes• Ni paste fired 1200-1300 C for 10 minutes (5% H2)

• DC measurements by 4-point probe technique• Silver conductivity σAg = 3.13 x 107 S/m• Nickel conductivity σNi = 1.50 x 107 S/m • Nickel has ½ th conductivity of silver and will contribute to

a higher device loss that silver.

D

Resonant Ring

Ring Resonator Measurements

Network Analyzer

Coax to Microstrip Adapter

RingResonator

1 cm

Resonant Behavior in Ring Resonators

-80

-70

-60

-50

-40

-30

-20

-10

0

5 10 15 20 25Frequency (GHz)

FDTDexperiment

|S21| (dB)

K=9.3

Semouchkina, Elena, Wenwu Cao, and Raj Mittra. "FDTD study of resonance processes in microstrip ring resonators with different excitation geometries." In 2001 IEEE MTT-S International Microwave Sympsoium Digest (Cat. No. 01CH37157), vol. 3, pp. 2055-2058. IEEE, 2001.

Tran

smis

sion

Coe

ffici

ent (

dB)

Electric Field perpendicular to substrate plane

Ring Resonator Loss Characterization

-50

-40

-30

-20

-10

0

1 2 3 4 5Frequency (GHz)

experiment

FDTD

|S21| (dB)

Δf

3dB

S 21(d

B)

fr

Frequency (GHz)

Tran

smis

sion

Coe

ffici

ent,

S 21

(dB

)

QT=Δf

fr

QT ≡ EM Energy Stored in Ring Resonator

EM Energy dissipated in Ring Resonator

1

tan δproportional to

Measured Q-factors Screen Printed Ring Resonators

n fr

(GHz)QT

1 4.0 332 7.9 503 11.8 83

n fr

(GHz)QT

1 4.0 912 7.9 1523 11.8 160

Nickel Ring on Alumina Substrate Silver Ring on Alumina Substrate

• Recall that the conductivity of Nickel is ½ that of silver • Recall that Q of the substrate Qd> 1,000 • Q is dominated by metal loss

Surface Resistance (Rs) of Conductors

Where:f = frequencyμ = relative permeabilityρ = resistivity

𝑅𝑅𝑠𝑠 = 𝜋𝜋 � 𝑓𝑓 � 𝜇𝜇 � 𝜌𝜌

Permeability of Ni is low at microwave frequency, but it contributes to the loss of a stripline structure

nFrequency

(GHz) μrAverage (std.)

1 3.9 5.12 (0.9)

2 7.8 5.43 (0.7)

3 11.7 2.17 (0.3)

=

Ag

Ni

c

cr

Ni

Ag

Ni QQ

σσµ

2

DC CharacterizationMicrowaveCharacterization

Dielectric and Conductor Contributions to RF loss over a large Q range

10-1 101 103 105 107 109

Argonne National LabHaines et al.

MEMC

Grey Matter

Dielectric Resonators

Superconducting Cavities

Ring Resonators

Q = 1𝑡𝑡𝑡𝑡𝑡𝑡𝛿𝛿

= 𝜔𝜔 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝑡𝑡𝐴𝐴𝐴𝐴 𝐸𝐸𝑡𝑡𝐴𝐴𝐴𝐴𝐴𝐴𝐸𝐸 𝑆𝑆𝑡𝑡𝑆𝑆𝐴𝐴𝐴𝐴𝑆𝑆𝑃𝑃𝑆𝑆𝑃𝑃𝐴𝐴𝐴𝐴 𝐿𝐿𝑆𝑆𝑠𝑠𝑠𝑠

Attenuation in Transmission Lines in the 10 GHz Range

Microstrip0.05< α<0.5 dB/cm

Coplanar Waveguide0.05< α<0.5 dB/cm

Waveguide0.001< α 0.005 dB/cm

Dielectric Conductor

Ponchak, George E et al. IEEE transactions on microwave theory and techniques 47, no. 2 (1999): 241-243.Hauhe, Mark S. et al. IEEE Transactions on Components, Packaging, and Manufacturing Technology: Part B 20, no. 3 (1997): 279-291.https://www.microwaves101.com/encyclopedias/waveguide-loss

Dielectric Waveguide for Low Loss Transmission

• Tractable Fabrication• Surface Metallization• Conducting via fence• Dielectric- or air-filled

Rectangular Waveguides

• Low Loss• Propagation loss governed

by dielectric loss• Attenuation is 0.04-0.2

dB/cm at 30 GHzBy VK Vivien - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=89268753

Metallic layers

Metallic vias

Substrate

Substrate Integrated Waveguide (SIW)

Summary of material

properties for 5G

• Device design dictates required material properties

• Transmission line configuration will place more emphasis on the dielectric or the metal loss

• Both dielectric and metal losses increase with frequency in the 5G frequency range

• Trade-offs in dielectric properties• Fundamental polarization mechanisms dictate the relationships

between dielectric constant, loss and temperature coefficient• Dk ↑ tanδ ↑, τT ↑

• Trends in material design for higher frequency 5G• Ability for have smooth metal traces on the dielectric.• Lower permittivity – because of design tolerances to dimensions• Reduce loss at higher freqeuncy

Broadband Dielectric Materials Characterization• Requires a fundamental understanding of circuits,

electromagnetics and optics.• MHz-GHz methods are useful for the characterization of:

• conduction in semiconductors, insulators, ionic conductors• Dipolar response in liquids and polymers

30Hz10Mm

DC 300Hz1Mm

3kHz100km

30kHz10km

300kHz1km

3MHz100m

30MHz10m

300MHz1m

3GHz100mm

30GHz10mm

300GHz1mm

3THz100μm

30THz10μm

300THz1μm

3PHz100nm

Terahertz

FTIR

Electronics

Microwaves

Photonics

IR

Vector network analysis

SpectrometerLow frequency impedance

Rajab, K. Z., Dougherty, J. P., & Lanagan, M. T. (2009). Dielectric properties at millimeter-wave and THz bands. In Advanced Millimeter-Wave Technologies: Antennas, Packaging and Circuits(pp. 49-69). John Wiley & Sons, Ltd.

1.E+06 1.E+07 1.E+08 1.E+09 1.E+10 1.E+11

Frequency, Hz

1.E-02

* Compass Technology Group and AFRL

Swiss to 12 MCKMeasurement

Techniques at Penn State

Lens Based Focused Beamand Free Space*

Split Cavity

LCR Parallel Plate Fabry Perot Open Resonator

Coaxial Line

5G Frequency Range

Broadband Characterization of 3D Printable Dielectrics

• Useful permittivity and loss ranges to benchmark MHz-THz measurement methods

• Print a range of sample sizes and geometries

d3mm to

1cm t1mm to

1cmWide range of dimensions needed for RF dielectric characterization

Technique d tPlates for free space 10 cm 2 mmThin disks for capacitors and split cavity 3 cm 1 mmCylinders for resonant post 2 cm 1 cmSmall disks for reflection 3 mm 1 mm

* Verowhite acrylate samples fabricated on Stratasys system by Danny Zhu (Werner Group)

Low Frequency Parallel Plate MethodImpedance Analyzer 10-3 to 104 Hz Impedance Analyzer 102 to 106 Hz

tACap roεε

=

Sample Holder

Low Frequency Parallel Plate Method for Polymer Characterization*

1.E-02

2.E-02

3.E-02

3.8

4

4.2

1.E+02 1.E+03 1.E+04 1.E+05 1.E+06

Diel

ectr

ic L

oss

Rela

tive

Diel

ectr

ic P

erm

ittiv

ity

Log (frequency)

εr = ′ ε r − j ′ ′ ε r

tanδ =′ ′ ε r′ ε r

High Frequency Coaxial Probe up to 2 GHz

to VNA

Inside conductor

Shorted endSample

Reference plane

Coaxial cable

Keysight P9374A USB VNAVector Network Analyzer

keysight.com

SampleDiameter: 3mm

Frequency range from 300 kHz up to 20 GHz

Split Cavity Test of Dielectric Substrates

3D printed polymer @ 17.73 GHz*

Dielectric Permittivity 2.84

Dielectric Loss 2.2e-2

> 2.5 cm

≈1 mm

* Verowhite acrylate samples fabricated on Stratasys system by Danny Zhu (Werner Group)

≈ 5 cm

W-band (75-110 GHz) Free Space System*Network Analyzer

Sample holder fixtured between two antennae

> 8 cm

2-5 mm

* Developed in collaboration with Brad Hoff under the AFRL Summer Faculty Fellow Program

Sample Dimensions

Broadband Measurement of Acrylate Polymer

Broadband Loss Measurement of Acrylate Polymer

38

Frequency Dependent Dielectric Relaxation Mechanisms

39From Principles of Electronic Materials and Devices, Third Edition, S.O. Kasap (© McGraw-Hill, 2005)

Amorphous polymers

Short Segments

Long Chain Segments

Loss

Dk or εr

Broadband Dielectric Properties of Pure Silica Glass

1.E-06

1.E-04

1.E-02

1.E+00

1.E+02

3.7

3.72

3.74

3.76

3.78

3.8

3.82

3.84

1.E+03 1.E+05 1.E+07 1.E+09 1.E+11 1.E+13

Rela

tive

Perm

ittiv

ity (

ε r)

Frequency (Hz)

Diel

ectr

ic L

oss (

tan

δ)

Westphal, W. B., & Sils, A. (1972). Dielectric constant and loss data, MIT insulation labGrischkowsky, D., Keiding, S., Van Exter, M., & Fattinger, C. (1990). Far-infrared time-domain spectroscopy with terahertz beams of dielectrics and semiconductors. JOSA B, 7(10), 2006-2015.Afsar, M. N. (1984). Dielectric measurements of millimeter-wave materials. IEEE Transactions on Microwave Theory and Techniques, 32(12), 1598-1609.

The role of glass in microwave and mm-wave devices

• Low Temperature Cofired Ceramics• Part of recrystallizable systems• Sintering aid for tape and inks

• Potential substrate?• Is the loss too high as we approach 30 GHz?

• Glass covers for 1 kW microwave sourceshttps://www.artikel-presse.de/wp-content/uploads/2018/06/Low-Temperature-Co-fired-Ceramic-LTCC.jpg

5G Infrastructure and Materials Optimization

• Simulated 5G signal propagation paths in an office environment. • (adopted from Remcom)

Window Glass Composition

Chemical composition determined from Inductively Couple Plasma (ICP)

*Trace elements include barium, aluminum, iron, potassium and phosphorus

Oxide SiO2 Na2O CaO MgO Trace*

Mol % 71.6 12.6 9.2 6.3 <1

Network former

Glass modifier contributes to low frequency loss and conductivity

Glass modifier

50mm x 50mm 108mm x 108mm Thickness2.2mm (3/32 inch)3.2mm (1/8 inch)5.8mm (1/4 inch)

GHz Spectrum for Window Glass

How to Quantify the Fundamental Material Contributions to Microwave Loss for Glass

From Kasap

Alkali addition

Tetrahedral RotationOccurs at Higher Frequency for Amorphous Silicates

Tail influences mm-wave

or tanδ

5G Frequency Rangeor α

How do Tetrahedral Linkages affect Polarizability “α” in Silicate Glass?SilicaSi-O α=5.24

L. A. Lamberson, PhD, Cornell University, 2016.

Alkali silicate Si-O α= 5.36e

Researchgate.net

Alkaline AluminosilicateSi-O α=5.89

QuartzSi-O α=4.87

Lanagan, Michael T., et al. "Dielectric polarizability of alkali and alkaline-earth modified silicate glasses at microwave frequency." Applied Physics Letters 116.22 (2020): 222902.

4

Polarization Modes Contribute to Loss in mm-wave Frequency Range

Westphal, W. B., & Sils, A. (1972). Dielectric constant and loss data, MIT insulation labGrischkowsky, D., Keiding, S., Van Exter, M., & Fattinger, C. (1990). Far-infrared time-domain spectroscopy with terahertz beams of dielectrics and semiconductors. JOSA B, 7(10), 2006-2015.Afsar, M. N. (1984). Dielectric measurements of millimeter-wave materials. IEEE Transactions on Microwave Theory and Techniques, 32(12), 1598-1609.

5G Frequency RangeSi-O Tetrahedral Rotation

Alkali and Alkali Earth Modifiers

Materials for 5GMike Lanagan

ESMELECTROMAGNETIC

SIMULATIONFDTD, MoM, FEM

MATERIALSProperties and Processes

StructuresTransmission Lines, Antennas, Windows

PermittivityPermeabilityConductivity Integration

Tractable Fabrication