development of optical interconnect pcbs for high speed
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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)
ECOC Workshop4 22nd Sep, 2013 London
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
ECOC Workshop4 22nd Sep, 2013 London
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
ECOC Workshop4 22nd Sep, 2013 London
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 )
ECOC Workshop4 22nd Sep, 2013 London
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
ECOC Workshop4 22nd Sep, 2013 London
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
ECOC Workshop4 22nd Sep, 2013 London
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
ECOC Workshop4 22nd Sep, 2013 London
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
ECOC Workshop4 22nd Sep, 2013 London
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)
ECOC Workshop4 22nd Sep, 2013 London
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
ECOC Workshop4 22nd Sep, 2013 London
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
ECOC Workshop4 22nd Sep, 2013 London
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
ECOC Workshop4 22nd Sep, 2013 London
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