On the Road to 5G Advances in Enabling Technology: A Materials’ Perspective

Agenda

• Brief summary of 5G • Material choices

– PTFE, thermosets & newer resin systems

• Detailed electrical characterization – Dielectric constant – Insertion loss – Selecting the best copper choice for the application

• PCB manufacturing consideration – Building multilayer boards – Plating impact on circuit losses

• Open Q&A session

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Rogers ACS Value Proposition

• Over 60 years experience in high frequency materials

• Broadest portfolio of high performance circuit materials solutions

• First to market with differentiated, high-tech new products

• Reliability and quality customers can count on

• Collaborative problem solving with customers and strong design and fabrication support

• Strong OEM and fabricator relationships

• True global footprint

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Rogers ACS Markets 2016 Market leader of high frequency PCB materials for over 60 years

Mobile Internet Devices

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DTH Satellite Services

Communications Infrastructure

Auto, Medical Security

Aerospace, Defense & High Reliability

High Speed Digital Chip Scale Packaging

Brief Summary of 5G

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Mobile Data Driving Infrastructure Evolution & Growth

• Mobile data grew 4000X in past 10 years, will grow 8X by 2020

• Mobile video represents 55% of data in 2015, growing to 75% in 2020

• Global mobile devices per capita will be 1.5 by 2020

• Smart phones & phablets will be ~50% of all devices by 2020

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Defining 5G:

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Spectrum & Key Technologies for 5G

• Spectrum Allocation – Sub-6 GHz – 20 to 40 GHz – +60 GHz

• Key Technologies – Massive MIMO Antennas – Complex MLB structures

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Material Choices

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What PCB Materials are of Interest for 5G?

• Short Term: < 6GHz • Sensitive to Dk and thickness variation (3GHz to 6GHz) • Higher Thermal Conductivity High Dk for compact PA design • MLB processing compact designs

• Longer term: > 20 GHz (mmWave) • Thin low loss dielectrics, smooth copper for frequency bands up to

77 GHz. • Mechanical properties suitable for active device integration

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High Frequency PCB Material Choices

Dk 10 GHz

Df 10 GHz

CTE TC Comments

PTFE Low-Dk

2.2±0.02

0.0009 High PTFE content, no much glass, lowest loss

PTFE Mid-Dk

3.0±0.04 0.0012 Best balance of low loss and cost

Thermoset Mid-Dk

3.48±0.05

0.0037 Ease of fabrication delivers lowest cost solution

Thermoset High-Dk

6.15±0.15

0.0038 Dk similar to LTCC but with conventional PCB processing for lower costs

LCP 2.9±0.04 0.0025 Ultra-thin dielectrics

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Reduction in Temperature Rise Using Smooth Foil

10mil RO4350B IL = 1.5 dB 34°C rise

10.7mil RO4350B LoPro IL = 1.0 dB 19°C rise

Thermal image is the top view of circuit and in a black band area Black band is less than 1/10 wavelength and has insignificant impact on insertion loss (IL) The reported IL is for an 8” long circuit and connectors @ 3.3 GHz

RO4350B™ Insertion Loss With Different Copper Foil Types 0.010" laminate

-1.8

-1.6

-1.4

-1.2

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-0.6

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0.0

0 10 20 30 40 50 60Frequency (GHz)

Inse

rtio

n lo

ss (d

B/in

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RO4350B Standard Laminate

RO4350B LoPro™ Laminate

3.3 GHz testing at 85 Watts on 50Ω microstrip

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Detailed Electrical Characterization

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Factors Affecting Insertion Loss

Dk, Df, Thk

Copper roughness

Surface finish

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Dielectric Constant vs Frequency: Low-Dk, PTFE

• These materials offer a very stable Dk over two decades, less than 0.05 in change

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Dielectric Constant vs Frequency: Mid-Dk, PTFE

• Very stable with an 0.05 change Dk over two decades

• LCP materials change is 0.1 over the same frequency range

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Dielectric Constant vs Frequency: Mid-Dk, thermoset

• Using rough ED copper change is 0.15 for the two decades

• Same materials with smooth copper changes 0.075, due to the reduced effect on dispersion by using smoother copper foil

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MMWave Insertion Loss: PTFE materials Dk and Copper Effects

DiClad-® 880 (2.2) vs RO3003™ (3.0), with ED & RLD copper

Lower Dk of DiClad 880 helps reduce conductor loss due to wider 50Ohm trace

RLD copper offers lower loss, smooth foils are optimal at millimeter wave frequencies

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Insertion Loss Measurements RO3003™, RO4350B™ and CLTE-AT™ Laminates

Comparing RO3003 and RO4350B up to 30GHz

CLTE-AT data is modeled using MWI

Smooth and rough copper comparison

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PCB Manufacturing Considerations

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Thermoset Materials Designed for MLB’s Ideal for Integrated 5G system

• CTE (Coefficient of Thermal Expansion) X,Y matched to copper – minimizes bow and twist of PCB – allows construction of hybrid

MLB’s • Low CTE Z and high Tg

– plated through hole reliability • Fabricate similar to conventional

FR-4 • Effect on electrical performance

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Surface Finish Effect on Insertion Loss

• Plating finish increases insertion loss due to higher resistivity of metals vs. copper (except for silver)

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Current Density Models for Microstrip Transmission Line Circuits

Top view of microstrip transmission line circuit

• Models were done using the Professional version of Sonnet Software Rev. 15.54

• Material is 20mil thermoset DK 3.5 laminate with standard ½ oz. ED copper

• 50 ohm microstrip transmission line

• Frequency is at 2.6 GHz

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Comparison of Various Surface Finishes

Actual impact of plating will be dependent on grade actual circuit configuration (thickness, copper type)

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Open Q&A Session

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