Optical PCB Technology for In-Chassis Interconnects H-V Fabricator s View

Transcription

1 Optical PCB Technology for In-Chassis Interconnects H-V Fabricator s View Marika Immonen, Hui Yuan Jan, Long Xiu Zhu, Shi Xing Hong, Xiao L. Ren, Guoqiu Yan, Laixin Jiang, May Zhou 4 th Optical Interconnect in Data Centers Symposium ECOC Dusseldorf September 19, 2016 Advanced Development Corporate Technology Session 2: Bringing Technology to Market I

2 Contents TTM Optical PCB technology Motivation: High speed system and RF PCB Challenges On-board Optical Application Scenarios TTM Optical PCB Process and Materials Waveguide Functional Characteristics OE PCB Challenges in Production PhoxTrot project flash of results Demonstrators: PhoxDem09.01; PhoxDem09.02 Dual WG layer technology Glass OPCB technology PhoxDem09.03 in progress Summary and Key Takeaways 2

3 TTM PCB Product Spectrum RIGID PCBS HDI (HIGH DENSITY) FLEX & RIGID-FLEX RF / MICROWAVE IC PACKAGES SPECIALTY Multilayer up to 60+ layers Embedded passives Heavy copper up to 10 oz. Over 50 UL approved laminates Thickness up to.450 Panel Size up to 30"x 54" Thin core dielectrics Mixed Dielectric (Hybrid) Constructions RF and High Performance Designs Buried Resistance and Capacitance Constrained Core MLB HDI Microwave Up to 12L "anylayer" stacked uvia Structure 1.6 / 2.0 mil line / space Wide material and surface finish selections 14 mil, 6L ultra thin structure 3/7 mil uvia / Pad size 0.4 mm pitch BGA with 2 traces fanout Embedded, distributed and discrete passive components Type 2, 3 and 4 (double sided, multilayer and rigid-flex) 30+ layers Dimensions up to 24" x 48 Acrylic, epoxy and adhesive-less polyimide flex materials Over 50 rigid material options Thickness up.300" MIL-SPEC & UL Qualified Custom Surface Finishes Available High frequency / bandwidth designs Planar and screened resistors Dimensions up to 24" x 48 Mixed dielectrics (hybrids) Dielectric foam Conductive paste Plated cavities Formed (conformal) PCBs Optical machining 2,4,6 Layers (2+2+2 stacked via) BT material Wire bonding (ENEPIG, Soft gold, Hard gold) Military and Aerospace Certifications 1-68 Layers High Frequency (RF) Bandwidth Designs Buried Metal Core Construction Surface Mounted Heatsinks 3

4 COMPUTING AND COMMUNICATIONS SYSTEMS PCB S : Conventional, backplane, power, system rigid-flex/flex RF PCB s : antenna, base station power amplifier, microwave High Speed PCB Loss Reduction Requirements 4

5 Development for On-board Interconnections: Application Scenarios and Solution Space Polymer WG on carrier Flexible PWG links C2C Fiber flex plane backplanes IBM 2013 Molex Flexible PWG links C2M Glass interposer for optical IC Sumitomo 5 Image source: OIF CEI56G DEFINITIONS LR = Long reach 1m/ 39 MR = Medium reach 50cm/ 20 SR = Short reach 20cm/ 8 VSR = Very short reach 10-15cm/ 4-6 XSR = Extra short reach 5cm USR = Ultra short reach 1cm

6 TTM Optical/Electrical Circuit Board Technology Hybrid PCB w/ optical and copper signal layers Copper for power distribution and low speed Optical layers for high speed signals Embedded WGs, rigid/flex or flex OE PCBs Waveguides Passive components High density routings Channel termination Pluggable optical connectors Passive optical alignment Density over fiber connections Low-Loss Optical Materials and Process Optical Waveguide Components and Layer Integration Fan in/out structures and Connectors Multimode waveguides High density arrays Splitters, combiners and NxN couplers Low radius bendings, crossings Out-of-plane turns and vertical routings Optical connector interface Company Confidential 6

7 Waveguide and OE PCB Fabrication Flow CLAD1 CORE CLAD2 Optical layer steps Electrical Electrical layering steps Optical Electrical TTM MM optical layer fab process utilize existing infrastructure: No need of specialized equipment ELECTRICAL OPTICAL OPTICAL ELECTRICAL CLAD1 CORE CLAD2 Substrate or subcore Deposition and patterning of clad Deposition and patterning of core Deposition and patterning of clad Lamination with copper layers and finalization of O/E PCB 7

8 TTM Polymer Waveguides on PCB OPCB fabrication in 16 x20 production panel : Panel scale fabrication capability After clad1 layering (coating, soft bake, flood exposure, PEB) After waveguide core patterning (coating, softbake, imaging, PEB, development) 8

9 Product Example: 20L + 1 Opt Embedded 90Bend 18x L 1. mm RoC: m m L 2. mm Product with optical layers Optical layer 20 electrical layers with 1 optical layer Optical layers b/w L10/11 Dimension (WxH): 277 x 312 mm (10 x12 ) Core: 50µm, 250µm pitch Material: EMC EM-285 HF Optical patterns: straight, Thickness: 2.8mm (+/ )mm diagonal, 90 bends QUALIFICATION Process qualifications: drilling (via optical layer, high dense via arrays), plating, peel strong in customer existing product Reflow 4x 260 C; Thermal shock: solder float 9

10 MM-PWG Functional Chacteristics (λ= 850nm) INSERTION LOSS CROSSTALK CROSSING LOSS Waveguide length =20cm (8 ) L/S 50/200µm Spacing 200µm (8mil) aggressor Light IL: < 0.05 db/cm at 850nm (MMF) TL: db/cm at 850nm (MMF) TL: 0.4 db/cm at 1310nm (MMF) BEND LOSS Crosstalk isolation: -32 db < db/x (MMF) 90 < db/x (SMF) 90 < 0.17 db/x (MMF) 45 < 0.17 db/x (SMF) 45 RoC 5mm < 1.9 db (MMF) < 1.2dB (SMF) RoC 10mm < 1 db (MMF) < 1.2 db (SMF)

11 Results Reliability Tests: Solder Reflow (Tpeak=260 C, 5x), Temp/Humidity (85%RH/85 C), T/C (-40 C/+125 C) SOLDER REFLOW Solder reflow Test condition: 260C in air 5 cycles Sample: Waveguides on silicon substrate Results: Increase of ± db/cm (pass telcordia requirements) TEMPERATURE HUMIDITY Temperature humidity Test condition: 85%RH/85C 2000 hours Sample: Waveguides on silicon substrate Results: No measureable (< 10-5 db/cm*h) change in attenuation THERMAL CYCLING Thermal cycles Test condition: -40C/+125C 500 cycles Sample: Waveguides on silicon substrate Results: No measureable change in attenuation (± 0.005dB/cm)

12 2.4Tbps Waveguide Demonstrator with 25Gbps Embedded Optical Links Connector for power supply Interface to waveguides JOINT DEVELOPMENT Power supply test Embedded waveguide links 8x 12 WG ch sets/ board Total: 96 ch/board Capacity: 2.4Tbps OBT OBT RF I/O USB Interface Two OBTs in the link prototype. Launching to WGs via fiber jumpers Electrical I/O we use 6 MXP connectors (Huber-Suhner) The OBTs are controlled through the I 2 C interface M.Immonen, R.Zhang, M.Press, H.Tang, W. Lei, J.Wu, H. J.Yan, L.X.Zhu, M.Serbay, End-to-end Optical 25Gb/s Link Demonstrator with Embedded Waveguides, 90 Out-of-Plane Connector and On-board Optical Transceivers Board: 284 x 311 mm. Construction: 6L+1Optical No # of WGs: 96 ch (8 x 12 ch)/ board Th.2.P2.SC

13 Results Link Traffic Measurements at 25Gbps M.Immonen, R.Zhang, M.Press, H.Tang, W. Lei, J.Wu, H. J.Yan, L.X.Zhu, M.Serbay, End-to-end Optical 25Gb/s Link Demonstrator with Embedded Waveguides, 90 Out-of-Plane Connector and On-board Optical Transceivers Th.2.P2.SC

14 PhoxTrot EU FP7 FHG-IZM, Seagate, Compass Networks, Mellanox with partners [ ] PhoxTroT is a large-scale European research effort focusing on optical interconnects across the different hierarchy levels in Data Center and High-Performance Computing Systems: on-board, board-to-board and rack-to-rack Fraunhofer IZM (DE) Fraunhofer HHI (DE) Vertilas GmbH (DE) Seagate Technology Ltd (UK) ams AG (AT) TTM Technologies (HK) AMO GmbH (DE) ICCS/NTUA (EL) DAS Photonics SL (ES) Phoenix BV (NL) CERTH (EL) Compass Networks (IL) Bright Photonics BV (NL) CTI (EL) CNRS-UB (FR) CNRS-LPN (FR) KIT (DE) SDU (DK) UPVLC (ES) IMEC (BE) Mellanox (IL) TTM is developing: polymer waveguide PCBs and interface solutions 14

15 Storage Controller Card Emulator with Embedded Optical Layer PhoxTrot Demonstrator [PhoxDem09.01] M. Immonen, J.Wu, H. J. Yan, L. X. Zhu, P.Chen, T.Rapala-Virtanen, Development of electrooptical PCBs with embedded waveguides for data center and high performance computing applications, Proc. of SPIE 8991, Optical Interconnects XIV, Mar,

16 16 Electro-Optical Router with Optical Waveguide Connectivity Two router chips communicating via 2 14 WG arrays Two MTP connectors communicating with router chip via 2 12 WG arrays PCB: 16 layers, optical layer embedded into the board stack Chip-to-board optical connector Waveguides Waveguides Fibre-to-Board connector sockets PhoxDem09.02 Physical Specifications Board outline: 190 mm x 420 mm Stack-up: 16L +1Opt (b/w L8 and L9) embedded TX-RX 8Gbp/s -> 112 Gbps via board embedded polymer WGs Max capacity: 1.34Tbps with 168 I/O s; or Gbps/ch Two CEOS ASICs with on-chip optical interconnects 52 52mm BGA with 4000 electrical pins a router traffic manager incl. a switch fabric, queuing manager and egress processing. PhoxDem09.02 scaled down of functions of router chips e.g., not running L3 and switch fabric logic C2C link: 15cm length. Density: 4ch/mm with 250µm pitch Capacity: 16ch/mm 62.5µm pitch 2x12-ch mid-board MTP connectors (PhoxPlug02) 90 chip-on-board (3.6x0.5x0.2mm) 12-ch lensed MT (TE) The power budget ~ 8-10dB

17 HLC OE PCB : 16L + 1Opt (Embedded) Fabricated 16L + 1Opt unit - Top side Cross-section First complex HLC EOPCB with embedded MM polymer waveguide layer Besides optical waveguides, the board contains all required electrical layers and via structures (PTHs, n-pth, stacked and buried microvias) built around optical cores 2.03 mm +/- 0.2mm

18 Assembled [PhoxDem09.02] Demonstrator Showcased at OFC 2016 (Anaheim ) Compass Networks finished assembly of two CEOS ASICs (OE- router chips) and MTP fiber connector on TTM 16L+1Opt OPCB (Nov/2015) Two CEOS ASICs with on-chip optical interconnects mm BGA with 4000 electrical pins a router traffic manager incl. a switch fabric, queuing manager and egress processing. PhoxDem09.02 scaled down of functions of router chips e.g., not running L3 and switch fabric logic 18

19 Development of multilayer (dual-layer) OPCBs MM Dual-WG OPCB development First dual-layer units complete Varying core sizes: width µmx height 45-90µm Excellent layer-to-layer registration < +/-5µm 2L OPCB fabrication in 16 x20 production panel a b c e f g h i 19

20 PhoxTrot09.03 / HDP Joint Eco-System Demonstrator Complete demonstrator platform including chassis and cards JOINT EFFORT with HDP Optical Interconnect Phase 2 OE2.TD1 - Test daughtercard OE2 - OE2.BP1 - backplane (HDPuG) OE2.LC1 - Logic card (not shown) OE2.MC1 - Mezzanine card with Ultracomm engine and high speed RF connectors Features 1. Electro-optical backplane with embedded waveguides (OE2.BP1) 2. Separate, interchangeable flexible waveguides with optical ferrule terminations 3. Backplane connector receptacles (commercial and proprietary) 4. Out-of-plane coupling elements for MPO cables 5. Pluggable Test Daughtercard with embedded waveguides and out-of-plane MPO couplers (OE2.TD1) 6. Pluggable Mezzanine Card to house optical engine and high speed RF connectors 7. Optical fibre or waveguide connection between optical engine and backplane connector plug 20 TTM

21 PhoxDem09.03 Demonstrator Technologies Glass WG Backplane (PhoxDem09.03.BP2) Polymer WG Daughter Card (PhoxDem09.03.TD1B) Polymer WG Backplane (PhoxDem09.03.BP3) Mezzanine Card (PhoxDem09.03.MC2A) Huber Suhner MXP array connectors FCI OBT optical engine Polymer WG Flex BP 21

22 PhoxTrot Optical Fiber-to-PCB waveguide interfaces PhoxPlug05 with 90 MLA assembled in PhoxTest05.03 board PhoxPlug03 - Multimode waveguide In-plane coupling interface (narrow) PhoxPlug04 - Multimode waveguide out-of-plane coupling interface (narrow) PhoxPlug05 - Multimode waveguide out-of-plane coupling interface (wide) 22

23 TTM FHG Glass Optical PCB Technology Core Technology Development [Q1/2016-Q4/2016] Glass WG PCBs (MM-Glass, SM-Glass) for 1310nm, 1550nm Polymer WG tech, optics integration, connectors Glass OE PCB 23

24 PhoxDem09.03.BP2 Backplane w/ Glass WGs Glass waveguides FTG A DMC PN:021457A 24

25 Characterization: Cross-section of WGs with white light illumination (as built) Gradient-index glass waveguides Wavelength range is nm Low dispersion (graded index) Direct seamless access to external fiber networks Mechanical and thermal stable during PCB embedding Manufacturing on panel formats Glass is substrate material (direct die attachment) Measurement data from FHG IZM for as-built WGs Core w1 Core w2 ch1 ch2 ch

26 Flexible Polymer Waveguides 26

27 Photonic Packages and Single Mode Waveguide OPCBs for Silicon Photonics Motivation: Emerging packages with silicon photonics chip and optical transcever co-packaged with ASIC. Strategic direction by various companies Optical IO with fibers or waveguides off package Intra package (/interposer or carrier) links with optical waveguide 1. Polymer WGs on carrier 2. Polymer WGs on-module 3. Polymer WG fly over flexes off-pkg and C2C IBM 2013 IBM

28 Summary and Key Take Away TTM Optical Electrical PCB today TTM has panel scale WG fab process to support standard form factors in production environment low cost, high volume, existing infrastructure TTM has technology on polymer waveguide, glass waveguides, flexible WGs TRL level and maturity varies per optical technology & eco-system TTM OPCBs with MM waveguides show low loss WGs < 0.05 db/cm and ability to produce complex WG structures: Bends, over-crossings, cascades Optical polymer materials with shown compliance in HLC product (chemistries, drilling, plating) and reliability (reflow, thermal cycling) Connectors with various partners. Focus on scaling number of channels t and connector assembly routines Future steps Single mode waveguide technology on package & board level Single mode connectors with new set of challenges: novel solutions required (self aligning structures,..) Chip-to-WG interface connectors/interface needs more solutions 28

29 Acknowledgements: TTM Technologies X.H. Shi, X.L. Ren, G. Yan, L. Jiang, M. Zhou, R.S. Zhi, L. Liu Dow Corning Corp. K. Weidner, J. degroot, B. Swatowski, M. Mohamed Financial support from European Commission through FP7-ICT project PhoxTroT under Contract Please visit us at Booth #