development of optical interconnect pcbs for high speed

Development of Optical Interconnect PCBs for High Speed Electronic Systems - Fabricator's View

Marika Immonen Research & Development, TTM Asia Pacific BU

ECOC 2013 WS4 - Workshop on Technologies for Short Reach Optical Interconnects 22nd September 2013 London ExCeL, UK

Outline

• TTM Overview

• Advanced PCB Technology Trends

• TTM Optical PCB Development

• Collaboration Initiatives

• Summary and Conclusions

ECOC Workshop4 22nd Sep, 2013 London 2

TTM Technologies – A Leading Global PCB Fabricator

3

HDI PCBs Rigid/Flex

IC

substrates

• Leading global PCB fabricator - $1.3 bill. in revenue

• 15 specialized factories located in U.S. and China

• Approximately 20,000 employees worldwide

• Focused on advanced technology products

• Total customer solution: prototype through production

• Technology development coordinated with

customers’ needs

• Diversified end markets with broad customer base

Multilayer PCBs

Consumer

Small, light-weight Devices

Complex (Any Layer)

Interconnections Structures

Smaller Geometry (Line, Via,

Pad etc.) formation

Ultra thin laminates

Rigid, flex and rigid-flex

constructions

Incorporation of latest fine pitch

components

Infrastructure

Large, thick PCBs

High speed / low loss materials

Hybrid material constructions

Thermal management: metal

core / coin applications

Embedded active and passive

components

Blind and buried vias / via in

pad / back drilling

High aspect ratios

TECHNOLOGY

ECOC Workshop4 22nd Sep, 2013 London

Motivation – Current Path with Copper

Hitachi Chemicals 06’2013

STD = Standard; VLP = Very low profile < 5µm ; H-VLP = high very low provile (profile less) < 3µm

Mid-loss: HE 679G Dk 3.95 Df 0.012 hal-free. Low-loss: FX-2 Dk 3.45 Df 0.0058,

Ultra-low loss: LW-900G Dk 3.57 (E) Df 0.0048 (E), Dk 3.32 (NE) 0.0038 (NE). Hal-free

• For copper interconnect, scaling is limited due to fundamental obstacles (such as loss, crosstalk, reflection and parasitics)

• Significant increase in cost/ power consumption/ design efforts/ manufacturing challenges to achieve viable 20+ Gbps operation and beyond

Ultra low-loss (NE-glass) Ultra low-loss (E-glass) Mid loss (E-glass) Low loss (E-glass)


Advanced High Speed Networking & Infrastructure View

5

2013

2014

2012

2015

10 mil Drill

12:1 Aspect Ratio

24-26 Layer

wth VIPPO

Impedance 10% Mid-Low Loss

laminates

6.25 Gbps 12.5 Gbps 25 Gbps 50 Gbps

8 mil Drill

15:1 Aspect Ratio

26-28 Layer

wth VIPPO

Impedance 7.5 %

Low Loss

laminates

Backdrilling

+/- 7 mils

Low Profile

Foil

8 mil Drill

18:1 Aspect Ratio

28-34 Layer

wth VIPPO

Impedance 6 %

Very Low Loss

laminates Backdrilling

+/- 4 mils

Ultra Low

Profile Foil

Lab Insertion

Loss Testing

Fiber Weave

Mitigation

Registration

+/- 4 mils

Registration

+/- 3.5 mils

Registration

+/-2.5 mils

Ultra Low Loss

laminates Impedance 5 %

Chem-Bond

Or No Profile Foil

Production

Loss Testing

HDI 1-2

1-3 HDI 2+N+2

Seq. Lamination

Freq. Based

Simulation


Development Objective: Optical/Electrical PCBs

6

• Hybrid PCB with optical and electrical signal layers

• Optical manufacturing methods and tolerances compliant with conventional PCBs processes (reflow, lamination)

• Passive optical alignment and robust assembly routines

• Pluggable optical connectors for in-plane and out-of-plane connections

• Cost comparable to electrical solution

• Long-term stability and product compliance

Multimode

waveguides High density arrays Splitters, combiners

and NxN couplers Low radius bendings,

crossings Out-of-plane turns and vertical routings

Low-Loss Optical Materials and Process Optical Waveguide Components and Layer Integration Fan in/out structures and Connectors


TTM Optical PCB Technology Goals

7

Wa

ve

gu

ide

s

(on-b

oa

rd)

Fiber/

WG cable E/O/E

conv.

Wa

ve

gu

ide

s

(on-b

oa

rd)

E/O/E

conv.

Waveguides

(on-board)

• Waveguides embedded on backplane and cards

• Optical I/O close IC to avoid long high-speed traces on PCB

• Fiber-less Optical Engines in LGA/ BGA style packages (development products available)

FO/WG Optical PCB/ Backplane Embedded WG Optical PCB/ Backplane

• Waveguide links on midplane/backplane PCB

• Optical I/O close IC to avoid long high-speed traces on PCB

• Support fiber-optic mid-board Optical Engines

• OEs in LGA/ BGA package with MT-multimode parallel connection (commercial products available )


TTM O/E PCB with Embedded Polymer Waveguides

8

Dielectric &

copper layers

Optical signal

layer

Power and low

speed

Multimode

polymer

waveguides

SPECIFICATIONS

Wavelength: 850nm

Waveguide: Multimode 50x50 µm2 (nom).

WG Pitch: 250µm (in/out)

Optical Loss: < 0.05dB/cm

Construction: Rigid, rigid/flex OE PCB

Layer count: Typ. HLC

Layer count: 1 optical, 2L optical (RD)

CHIP-TO-CHIP

CHIP TO NETWORK

CARD TO BACKPLANE

PROPRIETARY INTER AND INTRA BOARD DATA LINKS


Waveguide Termination for Off-Board and Board-to-Board Connections

9

HDPUG/ Optical Interlinks

Connector with coupling

device for mid-board

vertical access; 90° turn

by built-in deflection

optics

Waveguides terminate with modified

board edge MT ferrules FCi

Development collaboration for pluggable coupling device and right angle

optical BP connector


10Gb/s Video Transmission Demonstrator

10

• Point-to-point video transmission link through

polymer waveguides on PCB

• 12-ch WG array length 30 cm (12”)

• Waveguides terminated by butt-coupled MT-RJ

connectors

• Two test channels utilized for video transmission

• 10G EPON modules Finisar XFP FTLX8511D3-

HW) as the 10Gbps optical transceivers


Industry Consortium Development Initiative – HDPUG

11

HDPUG Optical Interconnect PHASE 1

HDPUG OI PHASE 2

LINK TV1 – Optical/Copper PCB

Cisco, Xyratex, TTM, Dow Corning, OIL,

Amphenol, Flextronics

• Product-like demonstrator –

router/switch, data storage, HPC

• Embedded optical end-to-end links

• Realistic form factor and link lengths

• 25Gbps parallel transceivers and optical

connectors on cards OPTICAL

BACKPLANE

• Copper analysis up to 40GHz, 25 Gbps

• Ultra-low loss (Rogers RT6202),

mid-loss (HE679G, IS408)

• Optical SI analysis up to 25 Gbps

• Optical links tested using external

transceiver cards

• Reduced optical PCB form factor

LINK TV2 – Copper PCB

Cisco, Xyratex, Multek,

Amphenol, Flextronics

• Amphenol

• Dow Corning

• Dow EM

• Hitachi

• Isola

• Optical Interlinks

• Sy-Tech

• Rogers

• Cisco

• TTM

• A-Lu

• Boeing

• Celestica

• CEOS

• Ericsson

• Flextronics

• Multek

• Oracle

• Panasonic

• Philips

• ViaSystems

• Xyratex

• Fujitsu

• Huawei

• IBM

• Intel

• ITEQ

• Juniper

• National

Semicon.

• Nihon Superior

Contributors, Fabricators, Testers: Materials and connectors


Optical Waveguide Characteristics

12

1L Optical

14L copper

HDPUG / Dow Corning

Waveguide functional metrics * Material loss (SMF input, low-mode fill)

* Waveguide propagation loss (MMF input, high-mode fill)

* Channel loss at = 850 nm, loss spectra over = 600..1600 nm

* Bending loss in-plane (imaged guides) vs. ROC

* Crossover loss per cross per crossing angle

* Coupling loss with fibers

* Waveguide dispersion (1.4m 35” spiral)

* Any effect on optical properties

(refractive index, transmission)

per base material (FR-4, hal-free)

Waveguide links with connectors * Reflective Back Reflection Return Loss (OTDR)

* Signal integrity analysis (eye diagram, jitter, extinction ratio)


Standardization Activities – IEC TC86 JWG 9

13

IEC 62496-2 General Guidance for Test and Measurement

for Optical Circuit Boards (Draft)

• HDP is conducting WG testing as round robin

• 14L PCBs with WGs; three (3) WGs

suppliers; five (5) testing resources

• Primary test: Insertion loss @ 850nm

• Straight, 90 bends, cascaded

bends, spiral 1.4m

• Measurement conditions to be documented

per IEC 62496-2 draft waveguide test

numbering (WTN) guideline

• Collaboration with IEC TC86 for joint effort

• Measurement repeatability is crucial for future

commercial deployment of embedded optical

waveguide technology

• Repeatability of waveguide measurements

still very difficult to achieve due to lack of

clarity on how measurements are specified


PhoxTroT: FP7 Joint Research Project (2012-15)

PhoxTroT is a newly founded FP7 Integrated Project focusing on high-performance, low-energy

and cost and small-size optical interconnects across the different hierarchy levels in Data Centre and High-Performance Computing Systems: on-board, board-to-board and rack-to-rack.

Board-to-Board

On-Board

Rack-to-Rack

PhoxTrot = Photonics for High-Performance, Low-Cost and Low-Energy Data Centers and High Performance Computing Systems:

Terabit/s Optical Interconnect Technologies for On-Board, Board-to-Board and Rack-to-Rack data links

TE connectivity


Conclusions

• TTM scope to provide “pipe clean” path of the optical technology for a integration in future products

• O/E PCB development objects full compliance with panel scale fabrication and product form factors

• Complex board fabrication experience combined with high volume capabilities -> Competitive cost/performance and quick ramp-up from development to H/V

• Optical on-board is collaborative effort. End-Users and OEMs need to provide clear roadmaps for products & applications, supply chain to work together for solutions

15 ECOC Workshop4 22nd Sep, 2013 London

Thank You


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